This study investigates the influence of electropolymerization conditions on the deposition of polypyrrole(PPy)onto cotton-derived carbon fiber(CF)modified with reduced graphene oxide(rGO)for supercapacitors applicati...This study investigates the influence of electropolymerization conditions on the deposition of polypyrrole(PPy)onto cotton-derived carbon fiber(CF)modified with reduced graphene oxide(rGO)for supercapacitors applications using an experimental/theorical approach.The surface modification of CF by rGO and/or by PPy electrodeposited at 10,25 and 50 mV s^(-1) was thoroughly examined physicochemical and electrochemically.Composite electrodes comprising CF-rGo-PPy,synthesized via electropolymerization at 25 mV s^(-1),demonstrated a remarkable increase in capacitance,showcasing~742 F g^(-1) compared to 153 F g^(-1) for CF.SEM,N_(2)-surface area,XPS,and TD-DFT approach revealed that the higher capacitance observed in CF-rGo-PPy electrodes underscores the influence of morphology and charged nitrogen species on the electrochemical performance of these modified electrodes.Notably,this electrode material achieves a specific capacitance retention of~96%of their initial capacitance after 10000 cycles at 0.5 A g^(-1) measured in a two-electrodes cell configuration.This work also discusses the influence of the scan rate used for pyrrole electropolymerization on the pseudocapacitance contribution of PPy and its possible effect on the porosity of the material.These results highlight the importance of appropriate electropolymerization conditions that allow obtaining the synergistic effect between CF,rGO and PPy.展开更多
In recent years,paper-based functional materials have received extensive attention in the field of energy storage due to their advantages of rich and adjustable porous network structure and good flexibility.As an impo...In recent years,paper-based functional materials have received extensive attention in the field of energy storage due to their advantages of rich and adjustable porous network structure and good flexibility.As an important energy storage device,paper-based supercapacitors have important application prospects in many fields and have also received extensive attention from researchers in recent years.At present,researchers have modified and regulated paper-based materials by different means such as structural design and material composition to enhance their electrochemical storage capacity.The development of paper-based supercapacitors provides an important direction for the development of green and sustainable energy.Therefore,it is of great significance to summarize the relevant work of paper-based supercapacitors for their rapid development and application.In this review,the recent research progress of paper-based supercapacitors based on cellulose was summarized in terms of various cellulose-based composites,preparation skills,and electrochemical performance.Finally,some opinions on the problems in the development of this field and the future development trend were proposed.It is hoped that this review can provide valuable references and ideas for the rapid development of paper-based energy storage devices.展开更多
Supercapacitors(SCs)are considered promising energy storge systems because of their outstanding power density,fast charge and discharge rate and long-term cycling stability.The exploitation of cheap and efficient elec...Supercapacitors(SCs)are considered promising energy storge systems because of their outstanding power density,fast charge and discharge rate and long-term cycling stability.The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors.As the battery-type materials,transition metal phosphides(TMPs)possess high theoretical specific capacity,good electrical conductivity and superior structural stability,which have been extensively studied to be electrode materials for supercapacitors.In this review,we summarize the up-to-date progress on TMPs materials from diversified synthetic methods,diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors.In the end,we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.展开更多
MXenes are a family of two-dimensional(2D)layered transition metal carbides/nitrides that show promising potential for energy storage applications due to their high-specific surface areas,excellent electron conductivi...MXenes are a family of two-dimensional(2D)layered transition metal carbides/nitrides that show promising potential for energy storage applications due to their high-specific surface areas,excellent electron conductivity,good hydrophilicity,and tunable terminations.Among various types of MXenes,Ti_(3)C_(2)T_(x) is the most widely studied for use in capacitive energy storage applications,especially in supercapacitors(SCs).However,the stacking and oxidation of MXene sheets inevitably lead to a significant loss of electrochemically active sites.To overcome such challenges,carbon materials are frequently incorporated into MXenes to enhance their electrochemical properties.This review introduces the common strategies used for synthesizing Ti_(3)C_(2)T_(x),followed by a comprehensive overview of recent developments in Ti_(3)C_(2)T_(x)/carbon composites as electrode materials for SCs.Ti_(3)C_(2)T_(x)/carbon composites are categorized based on the dimensions of carbons,including 0D carbon dots,1D carbon nanotubes and fibers,2D graphene,and 3D carbon materials(activated carbon,polymer-derived carbon,etc.).Finally,this review also provides a perspective on developing novel MXenes/carbon composites as electrodes for application in SCs.展开更多
Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and supercapacitors.To increase the reliability of time–frequency analysis,a theoretical correlatio...Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and supercapacitors.To increase the reliability of time–frequency analysis,a theoretical correlation between frequency-domain stationary analysis and time-domain transient analysis is urgently required.The present work formularizes a thorough model reduction of fractional impedance spectra for electrochemical energy devices involving not only the model reduction from fractional-order models to integer-order models and from high-to low-order RC circuits but also insight into the evolution of the characteristic time constants during the whole reduction process.The following work has been carried out:(i)the model-reduction theory is addressed for typical Warburg elements and RC circuits based on the continued fraction expansion theory and the response error minimization technique,respectively;(ii)the order effect on the model reduction of typical Warburg elements is quantitatively evaluated by time–frequency analysis;(iii)the results of time–frequency analysis are confirmed to be useful to determine the reduction order in terms of the kinetic information needed to be captured;and(iv)the results of time–frequency analysis are validated for the model reduction of fractional impedance spectra for lithium-ion batteries,supercapacitors,and solid oxide fuel cells.In turn,the numerical validation has demonstrated the powerful function of the joint time–frequency analysis.The thorough model reduction of fractional impedance spectra addressed in the present work not only clarifies the relationship between time-domain transient analysis and frequency-domain stationary analysis but also enhances the reliability of the joint time–frequency analysis for electrochemical energy devices.展开更多
Hydrogel electrolytes hold great potential in flexible zinc ion supercapacitors(ZICs)due to their high conductivity,good safety,and flexibility.However,freezing of electrolytes at low temperature(subzero)leads to dras...Hydrogel electrolytes hold great potential in flexible zinc ion supercapacitors(ZICs)due to their high conductivity,good safety,and flexibility.However,freezing of electrolytes at low temperature(subzero)leads to drastic reduction in ionic conductivity and mechanical properties that deteriorates the performance of flexible ZICs.Besides,the mechanical fracture during arbitrary deformations significantly prunes out the lifespan of the flexible device.Herein,a Zn^(2+)and Li^(+)co-doped,polypyrrole-dopamine decorated Sb_(2)S_(3)incorporated,and polyvinyl alcohol/poly(N-(2-hydroxyethyl)acrylamide)double-network hydrogel electrolyte is constructed with favorable mechanical reliability,anti-freezing,and self-healing ability.In addition,it delivers ultra-high ionic conductivity of 8.6 and 3.7 S m^(-1)at 20 and−30°C,respectively,and displays excellent mechanical properties to withstand tensile stress of 1.85 MPa with tensile elongation of 760%,together with fracture energy of 5.14 MJ m^(-3).Notably,the fractured hydrogel electrolyte can recover itself after only 90 s of infrared illumination,while regaining 83%of its tensile strain and almost 100%of its ionic conductivity during−30–60°C.Moreover,ZICs coupled with this hydrogel electrolyte not only show a wide voltage window(up to 2 V),but also provide high energy density of 230 Wh kg^(-1)at power density of 500 W kg^(-1)with a capacity retention of 86.7%after 20,000 cycles under 20°C.Furthermore,the ZICs are able to retain excellent capacity even under various mechanical deformation at−30°C.This contribution will open up new insights into design of advanced wearable flexible electronics with environmental adaptability and long-life span.展开更多
Developing advanced battery-type materials with abundant active sites,high conductivity,versatile morphologies,and hierarchically porous structures is crucial for realizing high-quality hybrid supercapacitors.Herein,h...Developing advanced battery-type materials with abundant active sites,high conductivity,versatile morphologies,and hierarchically porous structures is crucial for realizing high-quality hybrid supercapacitors.Herein,heterogeneous FeS@NiS is synthesized by cationic Co doping via surface-structure engineering.The density functional theory(DFT)theoretical calculations are firstly performed to predict the advantages of Co dopant by improving the OH^(−)adsorption properties and adjusting electronic structure,benefiting ions/electron transfer.The dynamic surface evolution is further explored which demonstrates that CoFeS@CoNiS could be quickly reconstructed to Ni(Co)Fe_(2)O_(4)during the charging process,while the unstable structure of the amorphous Ni(Co)Fe_(2)O_(4)results in partial conversion to Ni/Co/FeOOH at high potentials,which contributes to the more reactive active site and good structural stability.Thus,the free-standing electrode reveals excellent electrochemical performance with a superior capacity(335.6 mA h g^(−1),2684 F g^(−1))at 3 A g^(−1).Furthermore,the as-fabricated device shows a quality energy density of 78.1 W h kg^(−1)at a power density of 750 W kg^(−1)and excellent cycle life of 92.1%capacitance retention after 5000 cycles.This work offers a facile strategy to construct versatile morphological structures using electrochemical activation and holds promising applications in energy-related fields.展开更多
Dual ion storage hybrid supercapacitors(HsCs)are considered as a promising device to overcome the limited energy density of existing supercapacitors while preserving high power and long cyclability.However,the develop...Dual ion storage hybrid supercapacitors(HsCs)are considered as a promising device to overcome the limited energy density of existing supercapacitors while preserving high power and long cyclability.However,the development of high-capacity anion-storing materials,which can be paired with fast charg-ing capacitive electrodes,lags behind cation-storing counterparts.Herein,we demonstrate the surface faradaic OH-storage mechanism of anion storing perovskite oxide composites and their application in high-performance dual ion HsCs.The oxygen vacancy and nanoparticle size of the reduced LaMnO_(3)(r-LaMnO_(3))were controlled,while r-LaMnO_(3) was chemically coupled with ozonated carbon nanotubes(oCNTs)for the improved anion storing capacity and cycle performance.As taken by in-situ and ex-situ spectroscopic and computational analyses,OH-ions are inserted into the oxygen vacancies coordi-nating with octahedral Mn with the increase in the oxidation state of Mn during the charging process or vice versa.Configuring OH-storing r-LaMnO_(3)/oCNT composite with Na*storing MXene,the as-fabricated aqueous dual ion HSCs achieved the cycle performance of 73.3%over 10,000 cycles,delivering the max-imum energy and power densities of 47.5 w h kg^(-1) and 8 kw kg^(-1),respectively,far exceeding those of previously reported aqueous anion and dual ion storage cells.This research establishes a foundation for the unique anion storage mechanism of the defect engineered perovskite oxides and the advancement of dual ion hybrid energy storage devices with high energy and power densities.展开更多
Nitrogen doping has been widely used to improve the performance of carbon electrodes in supercapacitors,particularly in terms of their high-frequency response.However,the charge storage and electrolyte ion response me...Nitrogen doping has been widely used to improve the performance of carbon electrodes in supercapacitors,particularly in terms of their high-frequency response.However,the charge storage and electrolyte ion response mechanisms of different nitrogen dopants at high frequencies are still unclear.In this study,melamine foam carbons with different configurations of surfacedoped N were formed by gradient carbonization,and the effects of the configurations on the high-frequency response behavior of the supercapacitors were analyzed.Using a combination of experiments and first-principle calculations,we found that pyrrolic N,characterized by a higher adsorption energy,increases the charge storage capacity of the electrode at high frequencies.On the other hand,graphitic N,with a lower adsorption energy,increases the speed of ion response.We propose the use of adsorption energy as a practical descriptor for electrode/electrolyte design in high-frequency applications,offering a more universal approach for improving the performance of N-doped carbon materials in supercapacitors.展开更多
MXene,a transition metal carbide/nitride,has been prominent as an ideal electrochemical active material for supercapacitors.However,the low MXene load limits its practical applications.As environmental concerns and su...MXene,a transition metal carbide/nitride,has been prominent as an ideal electrochemical active material for supercapacitors.However,the low MXene load limits its practical applications.As environmental concerns and sustainable development become more widely recognized,it is necessary to explore a greener and cleaner technology to recycle textile by-products such as cotton.The present study proposes an effective 3D fabrication method that uses MXene to fabricate waste denim felt into ultralight and flexible supercapacitors through needling and carbonization.The 3D structure provided more sites for loading MXene onto Z-directional fiber bundles,resulting in more efficient ion exchange between the electrolyte and electrodes.Furthermore,the carbonization process removed the specific adverse groups in MXenes,further improving the specific capacitance,energy density,power density and electrical conductivity of supercapacitors.The electrodes achieve a maximum specific capacitance of 1748.5 mF cm-2 and demonstrate remarkable cycling stability maintaining more than 94%after 15,000 galvanostatic charge/discharge cycles.Besides,the obtained supercapacitors present a maximum specific capacitance of 577.5 mF cm^(-2),energy density of 80.2μWh cm^(-2)and power density of 3 mW cm^(-2),respectively.The resulting supercapacitors can be used to develop smart wearable power devices such as smartwatches,laying the foundation for a novel strategy of utilizing waste cotton in a high-quality manner.展开更多
Multi-metal hydroxides possess unique physical and chemical properties,making them promising candidates for supercapacitor working electrodes.Enhancing their electrochemical performance can be achieved through a combi...Multi-metal hydroxides possess unique physical and chemical properties,making them promising candidates for supercapacitor working electrodes.Enhancing their electrochemical performance can be achieved through a combination with carbon materials.In this study,we synthesized a composite material by hydrothermally dispersed 4,6,and 10 wt%carbon nanotubes(CNT)into ternary cobaltbismuth-samarium hydroxide(CoBiSm-TOH).These nanocomposites were employed as the material for the working electrode in a supercapacitor.The findings reveal that at 1.5 A/g,the specific capacitance of CNT3@CoBiSm-TOH,using a three-electrode system,was found to be 852.91 F/g,higher than that of CoBi-BOH,CoBiSm-TOH,CNT1@CoBiSm-TOH and CNT5@CoBiSm-TOH-measuring 699.69,750.34,789.54 and 817.79 F/g,respectively.Moreover,CNT3@CoBiSm-TOH electrodes exhibited a capacitance retention of around 88%over 10,000 cycles.To demonstrate practical applicability,CNT3@CoBiSm-TOH was grown on woven carbon fiber(WCF),and a solid-state supercapacitor device was developed using the VARTM(vacuum-assisted resin transfer molding).This device displayed a specific capacitance of 272.67 F/g at 2.25 A/g.Notably,it achieved a maximum energy density of 53.01 Wh/kg at a power density of 750 W/kg and sustained excellent cycle stability over 50,000 cycles,maintaining 70%of its initial capacitance.These results underscore the importance of interfacial nanoengineering and provide crucial insights for the development of future energy storage devices.展开更多
MXene has been the limelight for studies on electrode active materials,aiming at developing supercapacitors with boosted energy density to meet the emerging influx of wearable and portable electronic devices.Despite i...MXene has been the limelight for studies on electrode active materials,aiming at developing supercapacitors with boosted energy density to meet the emerging influx of wearable and portable electronic devices.Despite its various desirable properties including intrinsic flexibility,high specific surface area,excellent metallic conductivity and unique abundance of surface functionalities,its full potential for electrochemical performance is hindered by the notorious restacking phenomenon of MXene nanosheets.Ascribed to its two-dimensional(2D)nature and surface functional groups,inevitable Van der Waals interactions drive the agglomeration of nanosheets,ultimately reducing the exposure of electrochemically active sites to the electrolyte,as well as severely lengthening electrolyte ion transport pathways.As a result,energy and power density deteriorate,limiting the application versatility of MXene-based supercapacitors.Constructing 3D architectures using 2D nanosheets presents as a straightforward yet ingenious approach to mitigate the fatal flaws of MXene.However,the sheer number of distinct methodologies reported,thus far,calls for a systematic review that unravels the rationale behind such 3D MXene structural designs.Herein,this review aims to serve this purpose while also scrutinizing the structure–property relationship to correlate such structural modifications to their ensuing electrochemical performance enhancements.Besides,the physicochemical properties of MXene play fundamental roles in determining the effective charge storage capabilities of 3D MXene-based electrodes.This largely depends on different MXene synthesis techniques and synthesis condition variations,hence,elucidated in this review as well.Lastly,the challenges and perspectives for achieving viable commercialization of MXene-based supercapacitor electrodes are highlighted.展开更多
Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are ...Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are plagued by the limited operation voltage window(typically≤2.3 V)and inherent corrosion of current collectors.Herein,a novel deep eutectic solvent(DES)-based electrolyte which uses formamide(FMD)as hydrogen-bond donor and sodium nitrate(NaNO_(3))as hydrogen-bond acceptor is demonstrated.The electrolyte exhibits the wide electrochemical stability window(3.14 V),high electrical conductivity(14.01 mScm^(-1)),good flame-retardance,anticorrosive property,and ultralow cost(7%of the commercial electrolyte and 2%of WIS).Raman spectroscopy and Density Functional Theory calculations reveal that the hydrogen bonds between the FMD molecules and NO_(3)^(-)ions are primarily responsible for the superior stability and conductivity.The developed NaNO_(3)/FMD-based coin cell supercapacitor is among the best-performing state-of-art DES and WIS devices,evidenced by the high voltage window(2.6 V),outstanding energy and power densities(22.77 Wh kg^(-1)at 630 W kg^(-1)and 17.37 kW kg^(-1)at 12.55 Wh kg^(-1)),ultralong cyclic stability(86%after 30000 cycles),and negligible current collector corrosion.The NaNO_(3)/FMD industry adoption potential is demonstrated by fabricating 100 F pouch cell supercapacitors using commercial aluminum current collectors.展开更多
As a new generation electrode materials for energy storage,perovskites have attracted wide attention because of their unique crystal structure,reversible active sites,rich oxygen vacancies,and good stability.In this r...As a new generation electrode materials for energy storage,perovskites have attracted wide attention because of their unique crystal structure,reversible active sites,rich oxygen vacancies,and good stability.In this review,the design and engineering progress of perovskite materials for supercapacitors(SCs)in recent years is summarized.Specifically,the review will focus on four types of perovskites,perovskite oxides,halide perovskites,fluoride perovskites,and multi-perovskites,within the context of their intrinsic structure and corresponding electrochemical performance.A series of experimental variables,such as synthesis,crystal structure,and electrochemical reaction mechanism,will be carefully analyzed by combining various advanced characterization techniques and theoretical calculations.The applications of these materials as electrodes are then featured for various SCs.Finally,we look forward to the prospects and challenges of perovskite-type SCs electrodes,as well as the future research direction.展开更多
The stacking and aggregation of graphene nanosheets have been obstacles to their application as electrode materials for microelectronic devices.This study deploys a one-step,scalable,facile electrochemical exfoliation...The stacking and aggregation of graphene nanosheets have been obstacles to their application as electrode materials for microelectronic devices.This study deploys a one-step,scalable,facile electrochemical exfoliation technique to fabricate nitrogen(N)and chlorine(Cl)co-doped graphene nanosheets(i.e.,N-Cl-G)via the application of constant voltage on graphite in a mixture of 0.1 mol/L H_(2)SO_(4)and 0.1 mol/L NH_(4)Cl without using dangerous and exhaustive operation.The introduction of Cl(with its large radius)and N,both with high electrical negativity,facilitates the modulation of the electronic structure of graphene and creation of rich structural defects in it.Consequently,in the as-constructed supercapacitors,N-Cl-G exhibits a high specific capacitance of 77 F/g at 0.2 A/g and remarkable cycling stability with 91.7%retention of initial capacitance after 20,000 cycles at 10 A/g.Furthermore,a symmetrical supercapacitor assembled with N-Cl-G as the positive and negative electrodes(denoted as N-Cl-G//N-Cl-G)exhibits an energy density of 3.38 Wh/kg at a power density of 600 W/kg and superior cycling stability with almost no capacitance loss after 5000 cycles at 5 A/g.This study provides a scalable protocol for the facile fabrication of high-performance co-doped graphene as an electrode material candidate for supercapacitors.展开更多
The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly co...The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly conductive polymer and a prospective pseudocapacitive materials for supercapacitors,yet the inferior cyclic stability and unpredictable polymerization patterns severely impede its real-world applicability.Here,for the first time,an innovative seed-induced in-situ polymerization assisted 3D printing strategy is proposed to fabricate PPy-reduced graphene oxide/poly(vinylidene difluoride-cohexafluoropropylene)(PVDF-HFP)(PPy-rGO/PH)electrodes with controllable polymerization behavior and exceptional areal mass loading.The preferred active sites uniformly pre-planted on the 3D-printed graphene substrates serve as reliable seeds to induce efficient polypyrrole deposition,achieving an impressive mass loading of 185.6 mg cm^(-2)(particularly 79.2 mg cm^(-2)for polypyrrole)and a superior areal capacitance of 25.2 F cm^(-2)at 2 mA cm^(-2)for a 12-layer electrode.In agreement with theses appealing features,an unprecedented areal energy density of 1.47 mW h cm^(-2)for a symmetrical device is registered,a rarely achieved value for other PPy/rGO-based supercapacitors.This work highlights a promising route to preparing high energy density energy storage modules for real-world applications.展开更多
Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices.In this regard,s...Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices.In this regard,silver(Ag)has attracted great attention in the design of efficient electrodes.Inspired by the house/building process,which means electing the right land,it lays a strong foundation and building essential columns for a complex structure.Herein,we report the construction of multifaceted heterostructure cobalt-iron hydroxide(CFOH)nanowires(NWs)@nickel cobalt manganese hydroxides and/or hydrate(NCMOH)nanosheets(NSs)on the Ag-deposited nickel foam and carbon cloth(i.e.,Ag/NF and Ag/CC)substrates.Moreover,the formation and charge storage mechanism of Ag are described,and these contribute to good conductive and redox chemistry features.The switching architectural integrity of metal and redox materials on metallic frames may significantly boost charge storage and rate performance with noticeable drop in resistance.The as-fabricated Ag@CFOH@NCMOH/NF electrode delivered superior areal capacity value of 2081.9μA h cm^(-2)at 5 mA cm^(-2).Moreover,as-assembled hybrid cell based on NF(HC/NF)device exhibited remarkable areal capacity value of 1.82 mA h cm^(-2)at 5 mA cm^(-2)with excellent rate capability of 74.77%even at 70 mA cm^(-2)Furthermore,HC/NF device achieved maximum energy and power densities of 1.39 mW h cm^(-2)and 42.35 mW cm^(-2),respectively.To verify practical applicability,both devices were also tested to serve as a self-charging station for various portable electronic devices.展开更多
The application of Mg-based electrochemical energy storage materials in high performance supercapacitors is an essential step to promote the exploitation and utilization of magnesium resources in the field of energy s...The application of Mg-based electrochemical energy storage materials in high performance supercapacitors is an essential step to promote the exploitation and utilization of magnesium resources in the field of energy storage.Unfortunately,the inherent chemical properties of magnesium lead to poor cycling stability and electrochemical reactivity,which seriously limit the application of Mg-based materials in supercapacitors.Herein,in this review,more than 70 research papers published in recent 10 years were collected and analyzed.Some representative research works were selected,and the results of various regulative strategies to improve the electrochemical performance of Mg-based materials were discussed.The effects of various regulative strategies(such as constructing nanostructures,synthesizing composites,defect engineering,and binder-free synthesis,etc.)on the electrochemical performance and their mechanism are demonstrated using spinelstructured MgX_(2)O_(4) and layered structured Mg-X-LDHs as examples.In addition,the application of magnesium oxide and magnesium hydroxide in electrode materials,MXene's solid spacers and hard templates are introduced.Finally,the challenges and outlooks of Mg-based electrochemical energy storage materials in high performance supercapacitors are also discussed.展开更多
Lignin-derived porous carbons have emerged as promising electrode materials for supercapacitors.However,the challenge remains in designing and controlling their structure to achieve ideal electrochemical performance d...Lignin-derived porous carbons have emerged as promising electrode materials for supercapacitors.However,the challenge remains in designing and controlling their structure to achieve ideal electrochemical performance due to the complex molecular structure of lignin and its intricate chemical reactions during the activation process.In this study,three porous carbons were synthesized from lignin by spray drying and chemical activation with vary-ing KOH ratios.The specific surface area and structural order of the prepared porous carbon continued to increase with the increase of the KOH ratio.Thermogravimetric-mass spectrometry(TG-MS)was employed to track the molecular fragments generated during the pyrolysis of KOH-activated lignin,and the mechanism of the thermochemical conversion was investigated.During the thermochemical conversion of lignin,KOH facili-tated the removal of H2 and CO,leading to the formation of not only more micropores and mesopores,but also more ordered carbon structures.The pore structure exhibited a greater impact than the carbon structure on the electrochemical performance of porous carbon.The optimized porous carbon exhibited a capacitance of 256 F g-1 at a current density of 0.2 A g-1,making it an ideal electrode material for high-performance supercapacitors.展开更多
In this work,the fabrication and characterization of the nanocomposite hydrogel,as a solid electrode in electro-chemical cell and gel electrolyte material using Indium titanium oxide/polyethylene terephthalate(ITO/PET...In this work,the fabrication and characterization of the nanocomposite hydrogel,as a solid electrode in electro-chemical cell and gel electrolyte material using Indium titanium oxide/polyethylene terephthalate(ITO/PET)flex-ible substrate for double-layer supercapacitors have been reported.The nanocomposite hydrogel composed of Arabic gum(AG),Acrylic acid(AA),reduced graphene oxide(RGO),and silver nanoparticles(AgNPs)was fab-ricated via a physical cross-linked polymerization reaction,in which the ascorbic acid was used as a reducing agent to generate AgNPs and to convert Graphene oxide(GO)to RGO during the polymerization reaction.The morphology and structural characteristics of nanocomposite hydrogel were investigated using atomic force microscopy(AFM),scanning electron microscope(SEM),Fourier transfer infrared(FTIR),and X-rayfluores-cence(XRF).Additionally,the effect of RGO and AgNPs on hydrogel stability was assessed through Thermogra-vimetric analysis(TGA)and differential scanning calorimetry(DSC),while its mechanical properties were studied using the nanoindentation test.Electrochemical impedance spectroscopy(EIS),and cyclic voltammetry(CV)were also conducted to study the electrochemical properties of the prepared hydrogel.The effects of AgNPs,RGO,and water content were all considered in the study of supercapacitor performance.The microstructural tests showed that the nanocomposite hydrogel has a relatively high swelling rate,which has a crucial effect on the capa-citance.Furthermore,the effects of increasing AgNP concentration and water content in the hydrogel matrix showed a significant improvement in its electrochemical performance,compared with that for Arabic gum poly acrylic acid(AGPAA)hydrogel itself,were the specific capacitance exhibited a significant enhancement,convert-ing from a low value to a substantially higher capacitance value.Moreover,when the nanocomposite hydrogel was used as the working electrode in an electrochemical cell with a hydrochloric acid(HCl)electrolyte solution,it exhibited good electrode performance.Additionally,using(ITO/PET)as aflexible substrate for nanocomposite hydrogel shows an improvement in their suitability for supercapacitor applications.Therefore,it is suggested that the fabricated hydrogel supercapacitor has potential applications in thefield of renewable and clean energy harvesting.展开更多
基金CONCYTEC and PROCIENCIA agencies from Peru in the framework of the call for Basic Research Projects2019-01[contract number401-2019-FONDECYT].
文摘This study investigates the influence of electropolymerization conditions on the deposition of polypyrrole(PPy)onto cotton-derived carbon fiber(CF)modified with reduced graphene oxide(rGO)for supercapacitors applications using an experimental/theorical approach.The surface modification of CF by rGO and/or by PPy electrodeposited at 10,25 and 50 mV s^(-1) was thoroughly examined physicochemical and electrochemically.Composite electrodes comprising CF-rGo-PPy,synthesized via electropolymerization at 25 mV s^(-1),demonstrated a remarkable increase in capacitance,showcasing~742 F g^(-1) compared to 153 F g^(-1) for CF.SEM,N_(2)-surface area,XPS,and TD-DFT approach revealed that the higher capacitance observed in CF-rGo-PPy electrodes underscores the influence of morphology and charged nitrogen species on the electrochemical performance of these modified electrodes.Notably,this electrode material achieves a specific capacitance retention of~96%of their initial capacitance after 10000 cycles at 0.5 A g^(-1) measured in a two-electrodes cell configuration.This work also discusses the influence of the scan rate used for pyrrole electropolymerization on the pseudocapacitance contribution of PPy and its possible effect on the porosity of the material.These results highlight the importance of appropriate electropolymerization conditions that allow obtaining the synergistic effect between CF,rGO and PPy.
基金supported by the fund of the National Natural Science Foundation of China(22078184,22171170)the China Postdoctoral Science Foundation(2019M653853XB)+1 种基金the Natural Science Advance Research Foundation of Shaanxi University of Science and Technology(2018QNBJ-03)Major Scientific and Technological Innovation Projects in Shandong Province(2019TSLH0316)
文摘In recent years,paper-based functional materials have received extensive attention in the field of energy storage due to their advantages of rich and adjustable porous network structure and good flexibility.As an important energy storage device,paper-based supercapacitors have important application prospects in many fields and have also received extensive attention from researchers in recent years.At present,researchers have modified and regulated paper-based materials by different means such as structural design and material composition to enhance their electrochemical storage capacity.The development of paper-based supercapacitors provides an important direction for the development of green and sustainable energy.Therefore,it is of great significance to summarize the relevant work of paper-based supercapacitors for their rapid development and application.In this review,the recent research progress of paper-based supercapacitors based on cellulose was summarized in terms of various cellulose-based composites,preparation skills,and electrochemical performance.Finally,some opinions on the problems in the development of this field and the future development trend were proposed.It is hoped that this review can provide valuable references and ideas for the rapid development of paper-based energy storage devices.
基金supported by National Undergraduate Training Programs for Innovations[grant number 202210225259]the Outstanding Youth Project of Natural Science Foundation in Heilongjiang Province(YQ2022E040)+3 种基金the Shandong Provincial Natural Science Foundation(ZR2022ME166)the Postdoctoral Scientific Research Developmental Fund of Heilongjiang Province(LBH-Q20023)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(UNPYSCT-2020197)the 111 Project(B20088).
文摘Supercapacitors(SCs)are considered promising energy storge systems because of their outstanding power density,fast charge and discharge rate and long-term cycling stability.The exploitation of cheap and efficient electrode materials is the key to improve the performance of supercapacitors.As the battery-type materials,transition metal phosphides(TMPs)possess high theoretical specific capacity,good electrical conductivity and superior structural stability,which have been extensively studied to be electrode materials for supercapacitors.In this review,we summarize the up-to-date progress on TMPs materials from diversified synthetic methods,diverse nanostructures and several prominent TMPs and their composites in application of supercapacitors.In the end,we also propose the remaining challenges toward the rational discovery and synthesis of high-performance TMP electrodes materials for energy storage.
基金supported by the Basic Scientific Research Funds for Colleges and Universities affiliated to Hebei Province(JST2022005)Thanks are given to the financial support from the National Natural Science Foundation of China(22005099).
文摘MXenes are a family of two-dimensional(2D)layered transition metal carbides/nitrides that show promising potential for energy storage applications due to their high-specific surface areas,excellent electron conductivity,good hydrophilicity,and tunable terminations.Among various types of MXenes,Ti_(3)C_(2)T_(x) is the most widely studied for use in capacitive energy storage applications,especially in supercapacitors(SCs).However,the stacking and oxidation of MXene sheets inevitably lead to a significant loss of electrochemically active sites.To overcome such challenges,carbon materials are frequently incorporated into MXenes to enhance their electrochemical properties.This review introduces the common strategies used for synthesizing Ti_(3)C_(2)T_(x),followed by a comprehensive overview of recent developments in Ti_(3)C_(2)T_(x)/carbon composites as electrode materials for SCs.Ti_(3)C_(2)T_(x)/carbon composites are categorized based on the dimensions of carbons,including 0D carbon dots,1D carbon nanotubes and fibers,2D graphene,and 3D carbon materials(activated carbon,polymer-derived carbon,etc.).Finally,this review also provides a perspective on developing novel MXenes/carbon composites as electrodes for application in SCs.
基金support from the National Science Foundation of China(22078190)the National Key R&D Plan of China(2020YFB1505802).
文摘Joint time–frequency analysis is an emerging method for interpreting the underlying physics in fuel cells,batteries,and supercapacitors.To increase the reliability of time–frequency analysis,a theoretical correlation between frequency-domain stationary analysis and time-domain transient analysis is urgently required.The present work formularizes a thorough model reduction of fractional impedance spectra for electrochemical energy devices involving not only the model reduction from fractional-order models to integer-order models and from high-to low-order RC circuits but also insight into the evolution of the characteristic time constants during the whole reduction process.The following work has been carried out:(i)the model-reduction theory is addressed for typical Warburg elements and RC circuits based on the continued fraction expansion theory and the response error minimization technique,respectively;(ii)the order effect on the model reduction of typical Warburg elements is quantitatively evaluated by time–frequency analysis;(iii)the results of time–frequency analysis are confirmed to be useful to determine the reduction order in terms of the kinetic information needed to be captured;and(iv)the results of time–frequency analysis are validated for the model reduction of fractional impedance spectra for lithium-ion batteries,supercapacitors,and solid oxide fuel cells.In turn,the numerical validation has demonstrated the powerful function of the joint time–frequency analysis.The thorough model reduction of fractional impedance spectra addressed in the present work not only clarifies the relationship between time-domain transient analysis and frequency-domain stationary analysis but also enhances the reliability of the joint time–frequency analysis for electrochemical energy devices.
基金supported by the National Natural Science Foundation of China(52174247 and 22302066)“Hejian”Innovative Talent Project of Hunan Province(No.2022RC1088)+1 种基金the Hunan Provincial Natural Science Foundation(2023JJ40255)the Scientific Research Foundation of Hunan Provincial Education(22B0599 and 23A0442)。
文摘Hydrogel electrolytes hold great potential in flexible zinc ion supercapacitors(ZICs)due to their high conductivity,good safety,and flexibility.However,freezing of electrolytes at low temperature(subzero)leads to drastic reduction in ionic conductivity and mechanical properties that deteriorates the performance of flexible ZICs.Besides,the mechanical fracture during arbitrary deformations significantly prunes out the lifespan of the flexible device.Herein,a Zn^(2+)and Li^(+)co-doped,polypyrrole-dopamine decorated Sb_(2)S_(3)incorporated,and polyvinyl alcohol/poly(N-(2-hydroxyethyl)acrylamide)double-network hydrogel electrolyte is constructed with favorable mechanical reliability,anti-freezing,and self-healing ability.In addition,it delivers ultra-high ionic conductivity of 8.6 and 3.7 S m^(-1)at 20 and−30°C,respectively,and displays excellent mechanical properties to withstand tensile stress of 1.85 MPa with tensile elongation of 760%,together with fracture energy of 5.14 MJ m^(-3).Notably,the fractured hydrogel electrolyte can recover itself after only 90 s of infrared illumination,while regaining 83%of its tensile strain and almost 100%of its ionic conductivity during−30–60°C.Moreover,ZICs coupled with this hydrogel electrolyte not only show a wide voltage window(up to 2 V),but also provide high energy density of 230 Wh kg^(-1)at power density of 500 W kg^(-1)with a capacity retention of 86.7%after 20,000 cycles under 20°C.Furthermore,the ZICs are able to retain excellent capacity even under various mechanical deformation at−30°C.This contribution will open up new insights into design of advanced wearable flexible electronics with environmental adaptability and long-life span.
基金financial support from the Chang Jiang Scholars Program (51073047)the National Natural Science Foundation of China (51773049)+5 种基金the China Aerospace Science and Technology Corporation-Harbin Institute of Technology Joint Center for Technology Innovation Fund (HIT15-1A01)the Harbin City Science and Technology Projects (2013DB4BP031 and RC2014QN017035)the Natural Science Foundation of Shandong Province of China (ZR2023QE071)the College Students’ Innovation and Entrepreneurship Training Program Projects of Shandong Province (S202211065048)the Scientific Research Foundation of Qingdao University (DC1900009425)the China Postdoctoral Science Foundation (2022TQ0282)
文摘Developing advanced battery-type materials with abundant active sites,high conductivity,versatile morphologies,and hierarchically porous structures is crucial for realizing high-quality hybrid supercapacitors.Herein,heterogeneous FeS@NiS is synthesized by cationic Co doping via surface-structure engineering.The density functional theory(DFT)theoretical calculations are firstly performed to predict the advantages of Co dopant by improving the OH^(−)adsorption properties and adjusting electronic structure,benefiting ions/electron transfer.The dynamic surface evolution is further explored which demonstrates that CoFeS@CoNiS could be quickly reconstructed to Ni(Co)Fe_(2)O_(4)during the charging process,while the unstable structure of the amorphous Ni(Co)Fe_(2)O_(4)results in partial conversion to Ni/Co/FeOOH at high potentials,which contributes to the more reactive active site and good structural stability.Thus,the free-standing electrode reveals excellent electrochemical performance with a superior capacity(335.6 mA h g^(−1),2684 F g^(−1))at 3 A g^(−1).Furthermore,the as-fabricated device shows a quality energy density of 78.1 W h kg^(−1)at a power density of 750 W kg^(−1)and excellent cycle life of 92.1%capacitance retention after 5000 cycles.This work offers a facile strategy to construct versatile morphological structures using electrochemical activation and holds promising applications in energy-related fields.
基金supported by the National Research Foundation of Korea grant funded by the Korea government(MSIT)(NRF-2020R1A3B2079803)the computational time provided by KISTI(KSC-2023-CRE-0166).
文摘Dual ion storage hybrid supercapacitors(HsCs)are considered as a promising device to overcome the limited energy density of existing supercapacitors while preserving high power and long cyclability.However,the development of high-capacity anion-storing materials,which can be paired with fast charg-ing capacitive electrodes,lags behind cation-storing counterparts.Herein,we demonstrate the surface faradaic OH-storage mechanism of anion storing perovskite oxide composites and their application in high-performance dual ion HsCs.The oxygen vacancy and nanoparticle size of the reduced LaMnO_(3)(r-LaMnO_(3))were controlled,while r-LaMnO_(3) was chemically coupled with ozonated carbon nanotubes(oCNTs)for the improved anion storing capacity and cycle performance.As taken by in-situ and ex-situ spectroscopic and computational analyses,OH-ions are inserted into the oxygen vacancies coordi-nating with octahedral Mn with the increase in the oxidation state of Mn during the charging process or vice versa.Configuring OH-storing r-LaMnO_(3)/oCNT composite with Na*storing MXene,the as-fabricated aqueous dual ion HSCs achieved the cycle performance of 73.3%over 10,000 cycles,delivering the max-imum energy and power densities of 47.5 w h kg^(-1) and 8 kw kg^(-1),respectively,far exceeding those of previously reported aqueous anion and dual ion storage cells.This research establishes a foundation for the unique anion storage mechanism of the defect engineered perovskite oxides and the advancement of dual ion hybrid energy storage devices with high energy and power densities.
文摘Nitrogen doping has been widely used to improve the performance of carbon electrodes in supercapacitors,particularly in terms of their high-frequency response.However,the charge storage and electrolyte ion response mechanisms of different nitrogen dopants at high frequencies are still unclear.In this study,melamine foam carbons with different configurations of surfacedoped N were formed by gradient carbonization,and the effects of the configurations on the high-frequency response behavior of the supercapacitors were analyzed.Using a combination of experiments and first-principle calculations,we found that pyrrolic N,characterized by a higher adsorption energy,increases the charge storage capacity of the electrode at high frequencies.On the other hand,graphitic N,with a lower adsorption energy,increases the speed of ion response.We propose the use of adsorption energy as a practical descriptor for electrode/electrolyte design in high-frequency applications,offering a more universal approach for improving the performance of N-doped carbon materials in supercapacitors.
基金The authors acknowledge the financial support from the National Natural Science Foundation of China(Nos.52073224,32201491)the Textile Vision Basic Research Program of China(No.J202110)+3 种基金the Scientific Research Project of Shaanxi Provincial Education Department,China(No.22JC035)the Advanced Manufacturing Technology Program of Xi’an Science and Technology Bureau,China(No.21XJZZ0019)the Research Fund for the Doctoral Program of Xi’an Polytechnic University(No.BS202053)the Youth Innovation Team of Shaanxi Universities and Institute of Flexible electronics and Intelligent Textile.
文摘MXene,a transition metal carbide/nitride,has been prominent as an ideal electrochemical active material for supercapacitors.However,the low MXene load limits its practical applications.As environmental concerns and sustainable development become more widely recognized,it is necessary to explore a greener and cleaner technology to recycle textile by-products such as cotton.The present study proposes an effective 3D fabrication method that uses MXene to fabricate waste denim felt into ultralight and flexible supercapacitors through needling and carbonization.The 3D structure provided more sites for loading MXene onto Z-directional fiber bundles,resulting in more efficient ion exchange between the electrolyte and electrodes.Furthermore,the carbonization process removed the specific adverse groups in MXenes,further improving the specific capacitance,energy density,power density and electrical conductivity of supercapacitors.The electrodes achieve a maximum specific capacitance of 1748.5 mF cm-2 and demonstrate remarkable cycling stability maintaining more than 94%after 15,000 galvanostatic charge/discharge cycles.Besides,the obtained supercapacitors present a maximum specific capacitance of 577.5 mF cm^(-2),energy density of 80.2μWh cm^(-2)and power density of 3 mW cm^(-2),respectively.The resulting supercapacitors can be used to develop smart wearable power devices such as smartwatches,laying the foundation for a novel strategy of utilizing waste cotton in a high-quality manner.
基金financially supported by 2024 Gyeongbuk Green Environment Support Center。
文摘Multi-metal hydroxides possess unique physical and chemical properties,making them promising candidates for supercapacitor working electrodes.Enhancing their electrochemical performance can be achieved through a combination with carbon materials.In this study,we synthesized a composite material by hydrothermally dispersed 4,6,and 10 wt%carbon nanotubes(CNT)into ternary cobaltbismuth-samarium hydroxide(CoBiSm-TOH).These nanocomposites were employed as the material for the working electrode in a supercapacitor.The findings reveal that at 1.5 A/g,the specific capacitance of CNT3@CoBiSm-TOH,using a three-electrode system,was found to be 852.91 F/g,higher than that of CoBi-BOH,CoBiSm-TOH,CNT1@CoBiSm-TOH and CNT5@CoBiSm-TOH-measuring 699.69,750.34,789.54 and 817.79 F/g,respectively.Moreover,CNT3@CoBiSm-TOH electrodes exhibited a capacitance retention of around 88%over 10,000 cycles.To demonstrate practical applicability,CNT3@CoBiSm-TOH was grown on woven carbon fiber(WCF),and a solid-state supercapacitor device was developed using the VARTM(vacuum-assisted resin transfer molding).This device displayed a specific capacitance of 272.67 F/g at 2.25 A/g.Notably,it achieved a maximum energy density of 53.01 Wh/kg at a power density of 750 W/kg and sustained excellent cycle stability over 50,000 cycles,maintaining 70%of its initial capacitance.These results underscore the importance of interfacial nanoengineering and provide crucial insights for the development of future energy storage devices.
基金supported by the Fundamental Research Grant Scheme by Ministry of Higher Education Malaysia(FRGS/1/2021/STG04/XMU/02/1 and FRGS/1/2022/TK09/XMU/03/2)the Xiamen University Malaysia Research Fund(XMUMRF/2023-C11/IENG/0056)。
文摘MXene has been the limelight for studies on electrode active materials,aiming at developing supercapacitors with boosted energy density to meet the emerging influx of wearable and portable electronic devices.Despite its various desirable properties including intrinsic flexibility,high specific surface area,excellent metallic conductivity and unique abundance of surface functionalities,its full potential for electrochemical performance is hindered by the notorious restacking phenomenon of MXene nanosheets.Ascribed to its two-dimensional(2D)nature and surface functional groups,inevitable Van der Waals interactions drive the agglomeration of nanosheets,ultimately reducing the exposure of electrochemically active sites to the electrolyte,as well as severely lengthening electrolyte ion transport pathways.As a result,energy and power density deteriorate,limiting the application versatility of MXene-based supercapacitors.Constructing 3D architectures using 2D nanosheets presents as a straightforward yet ingenious approach to mitigate the fatal flaws of MXene.However,the sheer number of distinct methodologies reported,thus far,calls for a systematic review that unravels the rationale behind such 3D MXene structural designs.Herein,this review aims to serve this purpose while also scrutinizing the structure–property relationship to correlate such structural modifications to their ensuing electrochemical performance enhancements.Besides,the physicochemical properties of MXene play fundamental roles in determining the effective charge storage capabilities of 3D MXene-based electrodes.This largely depends on different MXene synthesis techniques and synthesis condition variations,hence,elucidated in this review as well.Lastly,the challenges and perspectives for achieving viable commercialization of MXene-based supercapacitor electrodes are highlighted.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LY23E060004)Royal Society Newton Advanced Fellowship(No.52061130218)
文摘Safe operation of electrochemical capacitors(supercapacitors)is hindered by the flammability of commercial organic electrolytes.Non-flammable Water-in-Salt(WIS)electrolytes are promising alternatives;however,they are plagued by the limited operation voltage window(typically≤2.3 V)and inherent corrosion of current collectors.Herein,a novel deep eutectic solvent(DES)-based electrolyte which uses formamide(FMD)as hydrogen-bond donor and sodium nitrate(NaNO_(3))as hydrogen-bond acceptor is demonstrated.The electrolyte exhibits the wide electrochemical stability window(3.14 V),high electrical conductivity(14.01 mScm^(-1)),good flame-retardance,anticorrosive property,and ultralow cost(7%of the commercial electrolyte and 2%of WIS).Raman spectroscopy and Density Functional Theory calculations reveal that the hydrogen bonds between the FMD molecules and NO_(3)^(-)ions are primarily responsible for the superior stability and conductivity.The developed NaNO_(3)/FMD-based coin cell supercapacitor is among the best-performing state-of-art DES and WIS devices,evidenced by the high voltage window(2.6 V),outstanding energy and power densities(22.77 Wh kg^(-1)at 630 W kg^(-1)and 17.37 kW kg^(-1)at 12.55 Wh kg^(-1)),ultralong cyclic stability(86%after 30000 cycles),and negligible current collector corrosion.The NaNO_(3)/FMD industry adoption potential is demonstrated by fabricating 100 F pouch cell supercapacitors using commercial aluminum current collectors.
基金financial support from the National Natural Science Foundation of China(21676036)the Natural Science Foundation of Chongqing(CSTB2023NSCQ-MSX0580)the Graduate Research and Innovation Foundation of Chongqing(CYS-20040)。
文摘As a new generation electrode materials for energy storage,perovskites have attracted wide attention because of their unique crystal structure,reversible active sites,rich oxygen vacancies,and good stability.In this review,the design and engineering progress of perovskite materials for supercapacitors(SCs)in recent years is summarized.Specifically,the review will focus on four types of perovskites,perovskite oxides,halide perovskites,fluoride perovskites,and multi-perovskites,within the context of their intrinsic structure and corresponding electrochemical performance.A series of experimental variables,such as synthesis,crystal structure,and electrochemical reaction mechanism,will be carefully analyzed by combining various advanced characterization techniques and theoretical calculations.The applications of these materials as electrodes are then featured for various SCs.Finally,we look forward to the prospects and challenges of perovskite-type SCs electrodes,as well as the future research direction.
基金supported by National Science Foundation of China(No.52201254)Natural Science Foundation of Shandong Province(Nos.ZR2020MB090,ZR2020MB027,and ZR2020QE012)+1 种基金the project of“20 Items of University”of Jinan(No.202228046)the Taishan Scholar Project of Shandong Province(No.tsqn202306226)。
文摘The stacking and aggregation of graphene nanosheets have been obstacles to their application as electrode materials for microelectronic devices.This study deploys a one-step,scalable,facile electrochemical exfoliation technique to fabricate nitrogen(N)and chlorine(Cl)co-doped graphene nanosheets(i.e.,N-Cl-G)via the application of constant voltage on graphite in a mixture of 0.1 mol/L H_(2)SO_(4)and 0.1 mol/L NH_(4)Cl without using dangerous and exhaustive operation.The introduction of Cl(with its large radius)and N,both with high electrical negativity,facilitates the modulation of the electronic structure of graphene and creation of rich structural defects in it.Consequently,in the as-constructed supercapacitors,N-Cl-G exhibits a high specific capacitance of 77 F/g at 0.2 A/g and remarkable cycling stability with 91.7%retention of initial capacitance after 20,000 cycles at 10 A/g.Furthermore,a symmetrical supercapacitor assembled with N-Cl-G as the positive and negative electrodes(denoted as N-Cl-G//N-Cl-G)exhibits an energy density of 3.38 Wh/kg at a power density of 600 W/kg and superior cycling stability with almost no capacitance loss after 5000 cycles at 5 A/g.This study provides a scalable protocol for the facile fabrication of high-performance co-doped graphene as an electrode material candidate for supercapacitors.
基金financially supported by the National Natural Science Foundation of China(No.51933007,No.52373047,No.52302106)the Sichuan Youth Science and Technology Innovation Research Team Project(No.2022JDTD0012)+2 种基金the Program for Featured Directions of Engineering Multidisciplines of Sichuan University(No.2020SCUNG203)the Natural Science Foundation of Sichuan Province(No.2023NSFSC0418)the Program for State Key Laboratory of Polymer Materials Engineering(No.sklpme2022-3-10)。
文摘The tireless pursuit of supercapacitors with high energy density entails the parallel advancement of wellsuited electrode materials and elaborately engineered architectures.Polypyrrole(PPy)emerges as an exceedingly conductive polymer and a prospective pseudocapacitive materials for supercapacitors,yet the inferior cyclic stability and unpredictable polymerization patterns severely impede its real-world applicability.Here,for the first time,an innovative seed-induced in-situ polymerization assisted 3D printing strategy is proposed to fabricate PPy-reduced graphene oxide/poly(vinylidene difluoride-cohexafluoropropylene)(PVDF-HFP)(PPy-rGO/PH)electrodes with controllable polymerization behavior and exceptional areal mass loading.The preferred active sites uniformly pre-planted on the 3D-printed graphene substrates serve as reliable seeds to induce efficient polypyrrole deposition,achieving an impressive mass loading of 185.6 mg cm^(-2)(particularly 79.2 mg cm^(-2)for polypyrrole)and a superior areal capacitance of 25.2 F cm^(-2)at 2 mA cm^(-2)for a 12-layer electrode.In agreement with theses appealing features,an unprecedented areal energy density of 1.47 mW h cm^(-2)for a symmetrical device is registered,a rarely achieved value for other PPy/rGO-based supercapacitors.This work highlights a promising route to preparing high energy density energy storage modules for real-world applications.
基金supported by the National Research Foundation of Korea (NRF)grant funded by the Korean government (MSIP) (2018R1A6A1A03025708)。
文摘Direct growth of redox-active noble metals and rational design of multifunctional electrochemical active materials play crucial roles in developing novel electrode materials for energy storage devices.In this regard,silver(Ag)has attracted great attention in the design of efficient electrodes.Inspired by the house/building process,which means electing the right land,it lays a strong foundation and building essential columns for a complex structure.Herein,we report the construction of multifaceted heterostructure cobalt-iron hydroxide(CFOH)nanowires(NWs)@nickel cobalt manganese hydroxides and/or hydrate(NCMOH)nanosheets(NSs)on the Ag-deposited nickel foam and carbon cloth(i.e.,Ag/NF and Ag/CC)substrates.Moreover,the formation and charge storage mechanism of Ag are described,and these contribute to good conductive and redox chemistry features.The switching architectural integrity of metal and redox materials on metallic frames may significantly boost charge storage and rate performance with noticeable drop in resistance.The as-fabricated Ag@CFOH@NCMOH/NF electrode delivered superior areal capacity value of 2081.9μA h cm^(-2)at 5 mA cm^(-2).Moreover,as-assembled hybrid cell based on NF(HC/NF)device exhibited remarkable areal capacity value of 1.82 mA h cm^(-2)at 5 mA cm^(-2)with excellent rate capability of 74.77%even at 70 mA cm^(-2)Furthermore,HC/NF device achieved maximum energy and power densities of 1.39 mW h cm^(-2)and 42.35 mW cm^(-2),respectively.To verify practical applicability,both devices were also tested to serve as a self-charging station for various portable electronic devices.
基金financial support provided by Projects(no.2020CDJXZ001)the Fundamental Research Funds for the Central Universities+1 种基金the Technology Innovation and Application Development Special Project of Chongqing(Z20211350 and Z20211351)Scientific Research Project of Chongqing Ecological Environment Bureau(no.CQEE2022-STHBZZ118)。
文摘The application of Mg-based electrochemical energy storage materials in high performance supercapacitors is an essential step to promote the exploitation and utilization of magnesium resources in the field of energy storage.Unfortunately,the inherent chemical properties of magnesium lead to poor cycling stability and electrochemical reactivity,which seriously limit the application of Mg-based materials in supercapacitors.Herein,in this review,more than 70 research papers published in recent 10 years were collected and analyzed.Some representative research works were selected,and the results of various regulative strategies to improve the electrochemical performance of Mg-based materials were discussed.The effects of various regulative strategies(such as constructing nanostructures,synthesizing composites,defect engineering,and binder-free synthesis,etc.)on the electrochemical performance and their mechanism are demonstrated using spinelstructured MgX_(2)O_(4) and layered structured Mg-X-LDHs as examples.In addition,the application of magnesium oxide and magnesium hydroxide in electrode materials,MXene's solid spacers and hard templates are introduced.Finally,the challenges and outlooks of Mg-based electrochemical energy storage materials in high performance supercapacitors are also discussed.
基金funding from the Key Research and Development Projects of Zhejiang Province(2022C01236)and the Ningbo Top Talent Project.
文摘Lignin-derived porous carbons have emerged as promising electrode materials for supercapacitors.However,the challenge remains in designing and controlling their structure to achieve ideal electrochemical performance due to the complex molecular structure of lignin and its intricate chemical reactions during the activation process.In this study,three porous carbons were synthesized from lignin by spray drying and chemical activation with vary-ing KOH ratios.The specific surface area and structural order of the prepared porous carbon continued to increase with the increase of the KOH ratio.Thermogravimetric-mass spectrometry(TG-MS)was employed to track the molecular fragments generated during the pyrolysis of KOH-activated lignin,and the mechanism of the thermochemical conversion was investigated.During the thermochemical conversion of lignin,KOH facili-tated the removal of H2 and CO,leading to the formation of not only more micropores and mesopores,but also more ordered carbon structures.The pore structure exhibited a greater impact than the carbon structure on the electrochemical performance of porous carbon.The optimized porous carbon exhibited a capacitance of 256 F g-1 at a current density of 0.2 A g-1,making it an ideal electrode material for high-performance supercapacitors.
基金The authors are grateful for the Jordan University of Science and Technology’s financial support for this research.This research was conducted under Grant No.20230333.
文摘In this work,the fabrication and characterization of the nanocomposite hydrogel,as a solid electrode in electro-chemical cell and gel electrolyte material using Indium titanium oxide/polyethylene terephthalate(ITO/PET)flex-ible substrate for double-layer supercapacitors have been reported.The nanocomposite hydrogel composed of Arabic gum(AG),Acrylic acid(AA),reduced graphene oxide(RGO),and silver nanoparticles(AgNPs)was fab-ricated via a physical cross-linked polymerization reaction,in which the ascorbic acid was used as a reducing agent to generate AgNPs and to convert Graphene oxide(GO)to RGO during the polymerization reaction.The morphology and structural characteristics of nanocomposite hydrogel were investigated using atomic force microscopy(AFM),scanning electron microscope(SEM),Fourier transfer infrared(FTIR),and X-rayfluores-cence(XRF).Additionally,the effect of RGO and AgNPs on hydrogel stability was assessed through Thermogra-vimetric analysis(TGA)and differential scanning calorimetry(DSC),while its mechanical properties were studied using the nanoindentation test.Electrochemical impedance spectroscopy(EIS),and cyclic voltammetry(CV)were also conducted to study the electrochemical properties of the prepared hydrogel.The effects of AgNPs,RGO,and water content were all considered in the study of supercapacitor performance.The microstructural tests showed that the nanocomposite hydrogel has a relatively high swelling rate,which has a crucial effect on the capa-citance.Furthermore,the effects of increasing AgNP concentration and water content in the hydrogel matrix showed a significant improvement in its electrochemical performance,compared with that for Arabic gum poly acrylic acid(AGPAA)hydrogel itself,were the specific capacitance exhibited a significant enhancement,convert-ing from a low value to a substantially higher capacitance value.Moreover,when the nanocomposite hydrogel was used as the working electrode in an electrochemical cell with a hydrochloric acid(HCl)electrolyte solution,it exhibited good electrode performance.Additionally,using(ITO/PET)as aflexible substrate for nanocomposite hydrogel shows an improvement in their suitability for supercapacitor applications.Therefore,it is suggested that the fabricated hydrogel supercapacitor has potential applications in thefield of renewable and clean energy harvesting.