A Better Zn-Ion Storage Device:Recent Progress for Zn-Ion Hybrid Supercapacitors

As a new generation of Zn-ion storage systems,Zn-ion hybrid supercapacitors(ZHSCs)garner tremendous interests recently from researchers due to the perfect integration of batteries and supercapacitors.ZHSCs have excellent integration of high energy density and power density,which seamlessly bridges the gap between batteries and supercapacitors,becoming one of the most viable future options for large-scale equipment and portable electronic devices.However,the currently reported two configurations of ZHSCs and corresponding energy storage mechanisms still lack systematic analyses.Herein,this review will be prudently organized from the perspectives of design strategies,electrode configurations,energy storage mechanisms,recent advances in electrode materials,electrolyte behaviors and further applications(micro or flexible devices)of ZHSCs.The synthesis processes and electrochemical properties of well-designed Zn anodes,capacitor-type electrodes and novel Zn-ion battery-type cathodes are comprehensively discussed.Finally,a brief summary and outlook for the further development of ZHSCs are presented as well.This review will provide timely access for researchers to the recent works regarding ZHSCs.

Towards High-Energy and Anti-Self-Discharge Zn-Ion Hybrid Supercapacitors with New Understanding of the Electrochemistry

Aqueous Zn-ion hybrid supercapacitors(ZHSs)are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance,high safety and low cost.Herein,high-energy and anti-self-discharge ZHSs are realized based on the fibrous carbon cathodes with hierarchically porous surface and O/N heteroatom functional groups.Hierarchically porous surface of the fabricated free-standing fibrous carbon cathodes not only provides abundant active sites for divalent ion storage,but also optimizes ion transport kinetics.Consequently,the cathodes show a high gravimetric capacity of 156 mAh g^(−1),superior rate capability(79 mAh g^(−1)with a very short charge/discharge time of 14 s)and exceptional cycling stability.Meanwhile,hierarchical pore structure and suitable surface functional groups of the cathodes endow ZHSs with a high energy density of 127 Wh kg−1,a high power density of 15.3 kW kg^(−1)and good anti-self-discharge performance.Mechanism investigation reveals that ZHS electrochemistry involves cation adsorption/desorption and Zn_(4)SO_(4)(OH)_(6)·5H_(2)O formation/dissolution at low voltage and anion adsorption/desorption at high voltage on carbon cathodes.The roles of these reactions in energy storage of ZHSs are elucidated.This work not only paves a way for high-performance cathode materials of ZHSs,but also provides a deeper understanding of ZHS electrochemistry.

All-Climate Stretchable Dendrite-Free Zn-Ion Hybrid Supercapacitors Enabled by Hydrogel Electrolyte Engineering

Hybrid supercapacitors have shown great potentials to fulfill the demand of future diverse applications such as electric vehicles and portable/wearable electronics.In particular,aqueous zinc-ion hybrid supercapacitors(ZHSCs)have gained much attention due to their low-cost,high energy density,and environmental friendliness.Nevertheless,typical ZHSCs use Zn metal anode and normal liquid electrolyte,causing the dendrite issue,restricted working temperature,and inferior device flexibility.Herein,a novel flexible Zn-ion hybrid supercapacitor(FZHSC)is developed by using activated carbon(AC)anode,δ-MnO_(2) cathode,and innovative PVA-based gel electrolyte.In this design,heavy Zn anode and its dendrite issue are avoided and layered cathode with large interlayer spacing is employed.In addition,flexible electrodes are prepared and integrated with an anti-freezing,stretchable,and compressible hydrogel electrolyte,which is attained by simultaneously using glycerol additive and freezing/thawing technique to regulate the hydrogen bond and microstructure.The resulting FZHSC exhibits good rate capability,high energy density(47.86 Wh kg^(−1);3.94 mWh cm^(−3)),high power density(5.81 kW kg^(−1);480 mW cm^(−3)),and excellent cycling stability(~91%capacity retention after 30000 cycles).Furthermore,our FZHSC demonstrates outstanding flexibility with capacitance almost unchanged even after various continuous shape deformations.The hydrogel electrolyte still maintains high ionic conductivity at ultralow temperatures(≤−30℃),enabling the FZHSC cycled well,and powering electronic timer robustly within an all-climate temperature range of−30~80℃.This work highlights that the promising Zn metal-free aqueous ZHSCs can be designed with great multifunctionality for more practical application scenarios.

Recent progress in flexible Zn-ion hybrid supercapacitors: Fundamentals, fabrication designs, and applications

One of the most exciting new developments in energy storage technology is flexible Zn-ion hybrid supercapacitors(f-ZIHSCs),which combine the high energy of Zn-ion batteries with high-power supercapacitors to satisfy the needs of portable flexible electronics.However,the development of f-ZHSCs is still in its infancy,and there are numerous barriers to overcome before they can be widely implemented for practical applications.This review gives an up-to-date description of recent achievements and underlying concepts in energy storage mechanisms of f-ZIHSCs and emphasizes the critical role of cathode,anode,and electrolyte materials systems in speeding the prosperity of f-ZIHSCs.The innovative nanostructured-based cathode materials for f-ZIHSCs include carbon(e.g.,porous carbon,heteroatom-doped carbon,biomass-derived porous carbon,graphene,etc.),metal-oxides,MXenes,and metal/covalentorganic frameworks,and other materials(e.g.,activated carbon,phosphorene,etc.)are mainly focused.Afterward,the latest developments in flexible anode and electrolyte frameworks and impacts of electrolyte compositions on the electrochemical properties of f-ZIHSC are elaborated.Subsequently,the advancements based on fabrication designs,including quasi-solid-state,micro,fiber-shaped,and all climate-changed f-ZIHSCs,are discussed in detail.Lastly,a summary of current challenges and recommendations for the future progress of advanced f-ZIHSC are addressed.This review article is anticipated to further understand the viable strategies and achievable approaches for assembling high-performance f-ZIHSCs and boost the technical revolutions on cathode,anode,and electrolytes for f-ZIHSC devices.

Recent progress and challenges of carbon materials for Zn-ion hybrid supercapacitors

Zinc-ion hybrid supercapacitors(ZHSCs)have garnered increasing attention as promising energy storage devices in recent years,as they combine the advantages of high-energy Zn-ion batteries and high-power supercapacitors.However,the development of ZHSCs is still in its infancy and there are many bottlenecks to overcome.In particular,the challenge induced by the limited ion adsorption capability of carbon-positive electrodes severely restricts the energy density of ZHSCs.Therefore,it has become a key issue to design novel carbon-positive electrodes that enable high energy density yet do not deteriorate the intrinsic power capability and long-term durability.This study focuses on recent achievements in synthesis,morphology,and electrochemical performance of various carbon materials applied in ZHSCs.The modification strategies to optimize their electrochemical performance are briefly summarized.In addition,current challenges and future opportunities in this field are also outlined.This review will be beneficial to provide an organized framework for the research systems of carbon-positive electrodes and develop novel ZHSCs with high energy density.

Dilute Aqueous-Aprotic Electrolyte Towards Robust Zn-Ion Hybrid Supercapacitor with High Operation Voltage and Long Lifespan

With the merits of the high energy density of batteries and power density of supercapacitors,the aqueous Zn-ion hybrid supercapacitors emerge as a promising candidate for applications where both rapid energy delivery and moderate energy storage are required.However,the narrow electrochemical window of aqueous electrolytes induces severe side reactions on the Zn metal anode and shortens its lifespan.It also limits the operation voltage and energy density of the Zn-ion hybrid supercapacitors.Using'water in salt'electrolytes can effectively broaden their electrochemical windows,but this is at the expense of high cost,low ionic conductivity,and narrow temperature compatibility,compromising the electrochemical performance of the Zn-ion hybrid supercapacitors.Thus,designing a new electrolyte to balance these factors towards high-performance Zn-ion hybrid supercapacitors is urgent and necessary.We developed a dilute water/acetonitrile electrolyte(0.5 m Zn(CF_(3)SO_(3))_(2)+1 m LiTFSI-H_(2)O/AN)for Zn-ion hybrid supercapacitors,which simultaneously exhibited expanded electrochemical window,decent ionic conductivity,and broad temperature compatibility.In this electrolyte,the hydration shells and hydrogen bonds are significantly modulated by the acetonitrile and TFSI-anions.As a result,a Zn-ion hybrid supercapacitor with such an electrolyte demonstrates a high operating voltage up to 2.2 V and long lifespan beyond 120,000 cycles.

Ag-integrated mixed metallic Co-Fe-Ni-Mn hydroxide composite as advanced electrode for high-performance hybrid supercapacitors

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.

Anion storing,oxygen vacancy incorporated perovskite oxide composites for high-performance aqueous dual ion hybrid supercapacitors

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.

Electrochemical Activation-Induced Structural Transformation in Ni(OH)_(2)/Ti_(3)C_(2)T_(x)/NF Systems with Enhanced Electrochemical Performance for Hybrid Supercapacitors

Exploring a novel strategy for large-scale production of battery-type Ni(OH)_(2)-based composites,with excellent capacitive performance,is still greatly challenging.Herein,we developed a facile and cost-effective strategy to in situ grow a layer of Ni(OH)_(2)/Ti_(3)C_(2)T_(x)composite on the nickel foam(NF)collector,where Ti_(3)C_(2)T_(x)is not only a conductive component,but also a catalyst that accelerates the oxidation of NF to Ni(OH)_(2).Detailed analysis reveals that the crystallinity,morphology,and electronic structure of the integrated electrode can be tuned via the electrochemical activation,which is beneficial for improving electrical conductivity and redox activity.As expected,the integrated electrode shows a specific capacity of 1.09 C cm^(-2)at 1 mA cm^(-2)after three custom activation cycles and maintains 92.4%of the initial capacity after 1500 cycles.Moreover,a hybrid supercapacitor composed of Ni(OH)_(2)/Ti_(3)C_(2)T_(x)/NF cathode and activated carbon anode provides an energy density of 0.1 mWh cm^(-2)at a power density of 0.97 mW cm^(-2),and excellent cycling stability with about 110%capacity retention rate after 5000 cycles.This work would afford an economical and convenient method to steer commercial Ni foam into advanced Ni(OH)_(2)-based composite materials as binder-free electrodes for hybrid supercapacitors.

CC@BCN@PANI core-shell nanoarrays as ultra-high cycle stability cathode for Zn-ion hybrid supercapacitors

Exploring cathode materials that combine excellent cycling stability and high energy density poses a challenge to aqueous Zn-ion hybrid supercapacitors(ZHSCs).Herein,polyaniline(PANI)coated boron-carbon-nitrogen(BCN)nanoarray on carbon cloth surface is prepared as advanced cathode materials via simple high-temperature calcination and electrochemical deposition methods.Because of the excellent specific capacity and conductivity of PANI,the CC@BCN@PANI core-shell nanoarrays cathode shows an excellent ion storage capability.Moreover,the 3D nanoarray structure can provide enough space for the volume expansion and contraction of PANI in the charging/discharging cycles,which effectively avoids the collapse of the microstructure and greatly improves the electrochemical stability of PANI.Therefore,the CC@BCN@PANI-based ZHSCs exhibit superior electrochemical performances showing a specific capacity of 145.8 mAh/g,a high energy density of 116.78 Wh/kg,an excellent power density of 12 kW/kg,and a capacity retention rate of 86.2%after 8000 charge/discharge cycles at a current density of 2 A/g.In addition,the flexible ZHSCs(FZHSCs)also show a capacity retention rate of 87.7%at the current density of 2 A/g after 450 cycles.

In-Situ Annealed Ti_(3)C_(2)T_(x) MXene Based All-Solid-State Flexible Zn-Ion Hybrid Micro Supercapacitor Array with Enhanced Stability

Zn-ion hybrid supercapacitors(SCs)are considered as promising energy storage owing to their high energy density compared to traditional SCs.How to realize the miniaturization,patterning,and flexibility of the Zn-ion SCs without affecting the electrochemical performances has special meanings for expanding their applications in wearable integrated electronics.Ti_(3)C_(2)T_(x) cathode with outstanding conductivity,unique lamellar structure and good mechanical flexibility has been demonstrated tremen-dous potential in the design of Zn-ion SCs,but achieving long cycling stability and high rate stability is still big challenges.Here,we proposed a facile laser writing approach to fabricate patterned Ti_(3)C_(2)T_(x)-based Zn-ion micro-supercapacitors(MSCs),followed by the in-situ anneal treatment of the assembled MSCs to improve the long-term stability,which exhibits 80%of the capacitance retention even after 50,000 charge/discharge cycles and superior rate stability.The influence of the cathode thickness on the electrochemical performance of the MSCs is also studied.When the thickness reaches 0.851μm the maximum areal capacitance of 72.02 mF cm^(−2)at scan rate of 10 mV s^(−1),which is 1.77 times higher than that with a thickness of 0.329μm(35.6 mF cm^(−2)).Moreover,the fab-ricated Ti_(3)C_(2)T_(x) based Zn-ion MSCs have excellent flexibility,a digital timer can be driven by the single device even under bending state,a flexible LED displayer of“TiC”logo also can be easily lighted by the MSC arrays under twisting,crimping,and winding conditions,demonstrating the scalable fabrication and application of the fabricated MSCs in portable electronics.

Asymmetric Zn-N_4 atomic sites embedded hollow fibers as stable Zn anode for high-performance Zn-ion hybrid capacitor

Zn based electrochemical energy storage systems(EES)have attracted tremendous interests owing to their low cost and high intrinsic safety.Nevertheless,the uncontrolled growth of Zn dendrites and the side reactions of Zn metal anodes(ZMAs)severely restrict their applications.To address these issues,we design the asymmetric Zn-N_(4) atomic sites embedded hollow fibers(AS-IHF)as the flexible host for stable ZMAs.Through introducing different nitrogen resources in the synthesis,two kinds of coordination,i,e.Zn-N(pyridinic)and Zn-N(pyrrolic),are introduced in the Zn-N_(4) atomic module synchronously.The asymmetric Zn-N_(4) module with regulated micro-environment facilitates the superior zincophilic features and promotes the Zn adsorption.Meanwhile,the highly porous structure of the hollow fiber effectively reduces local current density,homogenize Zn ion flux,and alleviate structure stress.All the advantages endow the high efficiency and good stability for Zn plating/stripping.Both theoretical and experimental results demonstrate the high reversibility,low nucleation overpotential,and dendritefree behavior of the AS-IHF@Zn anode,which afford the high stability in high-rate and long-term cycling.Moreover,the solid-state Zn-ion hybrid capacitor(ZIHC)based on AS-IHF@Zn anode shows the high flexibility,reliability,and superior long-term cycling capability in a wide-range of temperatures(-20-25℃).Therefore,the present work not only gives a new strategy for modulating local environments of single atomic sites,but also propels the development of flexible power sources for diverse electronics.

An aqueous magnesium-ion hybrid supercapacitor operated at-50℃

The recent advances in aqueous magnesium-ion hybrid supercapacitor(MHSC)have attracted great attention as it brings together the benefits of high energy density,high power density,and synchronously addresses cost and safety issues.However,the freeze of aqueous electrolytes discourages aqueous MHSC from operating at low-temperature conditions.Here,a low-concentration aqueous solution of 4 mol L^(-1) Mg(ClO_(4))_(2) is devised for its low freezing point(-67℃)and ultra-high ionic conductivity(3.37 mS cm^(-1) at-50℃).Both physical characterizations and computational simulations revealed that the Mg(ClO_(4))_(2) can effectively disrupt the original hydrogen bond network among water molecules via transmuting the electrolyte structure,thus yielding a low freezing point.Thus,the Mg(ClO_(4))_(2) electrolytes endue aqueous MHSC with a wider temperature operation range(-50℃–25℃)and a higher energy density of 103.9 Wh kg^(-1) at 3.68 kW kg^(-1) over commonly used magnesium salts(i.e.,MgSO_(4) and Mg(NO_(3))_(2))electrolytes.Furthermore,a quasi-solid-state MHSC based on polyacrylamide-based hydrogel electrolyte holds superior low-temperature performance,excellentflexibility,and high safety.This work pioneers a convenient,cheap,and eco-friendly tactic to procure low-temperature aqueous magnesium-ion energy storage device.

Recent Developments of Transition Metal Compounds-Carbon Hybrid Electrodes for High Energy/Power Supercapacitors

Due to their rapid power delivery,fast charging,and long cycle life,supercapacitors have become an important energy storage technology recently.However,to meet the continuously increasing demands in the fields of portable electronics,transportation,and future robotic technologies,supercapacitors with higher energy densities without sacrificing high power densities and cycle stabilities are still challenged.Transition metal compounds(TMCs)possessing high theoretical capacitance are always used as electrode materials to improve the energy densities of supercapacitors.However,the power densities and cycle lives of such TMCs-based electrodes are still inferior due to their low intrinsic conductivity and large volume expansion during the charge/discharge process,which greatly impede their large-scale applications.Most recently,the ideal integrating of TMCs and conductive carbon skeletons is considered as an effective solution to solve the above challenges.Herein,we summarize the recent developments of TMCs/carbon hybrid electrodes which exhibit both high energy/power densities from the aspects of structural design strategies,including conductive carbon skeleton,interface engineering,and electronic structure.Furthermore,the remaining challenges and future perspectives are also highlighted so as to provide strategies for the high energy/power TMCs/carbon-based supercapacitors.

The roles of graphene in advanced Li-ion hybrid supercapacitors

Lithium-ion hybrid supercapacitors （LIHSs）, also called Li-ion capacitors, are electrochemical energy stor- age devices that combining the advantages of high power density of supercapacitor and high energy density of Li-ion battery. However, high power density and long cycle life are still challenges for the cul~ rent LIHSs due to the imbalance of charge-storage capacity and electrode kinetics between capacitor-type cathode and battery-type anode. Therefore, great efforts have been made on designing novel cathode materials with high storage capacity and anode material with enhanced kinetic behavior for LIHSs. With unique two-dimensional form and numerous appealing properties, for the past several years, the rational designed graphene and its composites materials exhibit greatly improved electrochemical performance as cathode or anode for LIHSs. Here, we summarized and discussed the latest advances of the state- of-art graphene-based materials for LIHSs applications. The major roles of graphene are highlighted as （1） a superior active material, （2） ultrathin 2D flexible support to remedy the sluggish reaction of the metal compound anode, and （3） good 2D building blocks for constructing macroscopic 3D pOFOUS car- bonjgraphene hybrids. In addition, some high performance aqueous LIHSs using graphene as electrode were also summarized. Finally, the perspectives and challenges are also proposed for further develop- ment of more advanced graphene-based LIHSs.

New types of hybrid electrolytes for supercapacitors

Supercapacitors(SCs)are emerging as efficient energy storage devices but still suffering from limited energy density compared with batteries.Electrolytes have been regarded as the key to determine the energy storage performance of SCs.However,none of the conventional electrolytes can fully meet the increasing requirements of SCs in terms of high ion conductivity,excellent stability,wide voltage window and operating temperature range,as well as environmentally friend concerns.To this end,hybrid electrolytes have sprung up in recent years,which are believed to be the candidate to solve these shortcomings.Herein,the state-of-the-art types of hybrid electrolytes for SCs,including the combination of aqueous and organic,aqueous and gel polymer,ionic liquids(ILs)and organic,and ILs and gel polymer hybrid electrolytes,are reviewed.The effects of different hybrid systems on the performance of SCs and the underlying mechanisms are among the focal points of the review,and prospects and possible directions are discussed as well to provide further insight into the future development of this field.

Improving the charge kinetics through in-situ growth of NiSe nanoparticles on g-C_(3)N_(4)nanosheets for efficient hybrid supercapacitors

Nickel selenide(NiSe)has been a promising positive electrode for hybrid supercapacitors due to its multiple oxidation states,tunability,and high specific capacity.However,sluggish ion transfers and particle agglomeration hamper its electrochemical performance.In the present study,we have grown NiSe nanoparticles on two-dimensional(2D)graphitic carbon nitride(g-C_(3)N_(4))nanosheets to realize three-dimensional(3D)architecture.The 2D support,high nitrogen content,and features of g-C_(3)N_(4)enhanced the specific capacity of the NiSe/g-C_(3)N_(4)nanocomposite material.The resulting nanocomposite shows a specific capacity of 320 mA h g^(-1)at a current density of 1 A g^(-1),which is considerably higher than pristine NiSe.Later,the hybrid supercapacitor(HSC)device was fabricated using NiSe/g-C_(3)N_(4)composite as positive and activated carbon(AC)as negative electrodes.The cell delivered an energy density of 52.5 Wh kg^(-1)at a power density of 1488 W kg^(-1)with excellent cyclic stability of 84.9%over 8000 cycles.The electrochemical performance enhancement corresponds to a 3D structure,high electrochemical active sites,and improved charge transportation at the electrode/electrolyte interface.Thus,the present work offers an easy approach and architectural design for high-performance HSC.

A survey of hybrid energy devices based on supercapacitors

Developing multifunctional energy storage systems with high specific energy, high specific power and long cycling life has been the one of the most important research directions. Compared to batteries and traditional capacitors, supercapacitors possess more balanced performance with both high specific power and long cycle-life. Nevertheless, regular supercapacitors can only achieve energy storage without harvesting energy and the energy density is still not very high compared to batteries. Therefore, combining high specific energy and high specific power,long cycle-life and even fast self-charging into one cell has been a promising direction for future energy storage devices. The multifunctional hybrid supercapacitors like asymmetric supercapacitors, batteries/supercapacitors hybrid devices and self-charging hybrid supercapacitors have been widely studied recently. Carbon based electrodes are common materials used in all kinds of energy storage devices due to their fabulous electrical and mechanical properties. In this survey, the research progress of all kinds of hybrid supercapacitors using multiple effects and their working mechanisms are briefly reviewed. And their advantages and disadvantages are discussed. The hybrid supercapacitors have great application potential for portable electronics, wearable devices and implantable devices in the future.

Zinc-ion hybrid supercapacitors with ultrahigh areal and gravimetric energy densities and long cycling life

Zinc ion hybrid supercapacitor (ZIHSC) with promising energy and power densities is an excellent answer to the ever-growing demand for energy storage devices.The restricted lifespan due to the dendrite formation on metallic zinc (Zn) is one of the main roadblocks.Herein,we investigate the electrochemical capability of oxygen-enriched porous carbon nanofibers (A-CNF) and nitrogen,oxygen-enriched porous carbon nanofibers (N-CNF) cathode materials for structural ZIHSCs.To this end,a series of samples with different chemical compositions (N and O contents) are prepared to present deep insight into the electrochemical mechanism between N/O doping and Zn-ion storage.The as-prepared ZIHSC in the presence of N-CNF cathode and Zn Cl_(2) electrolyte offers a battery-level gravimetric energy density of 143.2 Wh kg^(-1)at a power density of 367.1 W kg^(-1).The free-standing N-CNF electrodes in ZIHSCs enjoy delivering an outstanding areal energy density of 110.4μWh cm^(-2)at 0.24 m W cm^(-2),excellent rate capability,and noticeable cycling stability over 10,000 cycles at 10 A g^(-1)with less than 7%decay.It was also concluded that active pyrrolic N dopants might deliver and facilitate more pseudocapacitance in ZIHSCs than other N configurations,resulting in higher adsorption/desorption and insertion/extraction process of Zn Cl^(+).Taking advantage of the beneficial properties of a free-standing continuous cathode,this novel generation of structural cathode material offers high areal and gravimetric energy densities and mechanical properties in a single zinc-ion-based package.

Recent progress in water splitting and hybrid supercapacitors based on nickel-vanadium layered double hydroxides

Environmentally friendly energy sources alternatives to fossil fuels such as solar and wind are strategic for meeting the needs of an increasingly energy demanding society,despite their periodic/intermittent nature.Thus,urge the development of clean and renewable energy sources such as based on solar energy and water in a cyclic way,by photoinduced water-splitting and regeneration in fuel cells.In this context,energy storage devices such as hybrid supercapacitors become fundamental for realization of a sustainable society.In this review,the early discovery and recent advances concerning synthetic strategies,hierarchical structures,and oxygen evolution reaction(OER)/hydrogen evolution reactions(HER) catalytic performances of nickel-vanadium double hydroxides(NiV-LDHs) based nanomaterials are summarized.A discussion about the role of vanadium ions in HER/OER was also included,highlighting the recent progress in theoretical calculations in this field.Finally,some hybrid supercapacitor electrode materials based on NiV-LDHs are described,including the strategies to circumvent the parasitic oxygen evolution reaction during charge-discharge of those energy storage devices.In short,catalysts for HER/OER and hybrid supercapacitor electrode materials based on NiV-LDHs were reviewed considering their key multifunctional role in the way to a more sustainable society.