Lignin waste from the papermaking and biorefineries industry is a significantly promising renewable resource to prepare advanced carbon materials for diverse applications,such as the electrodes of supercapacitors;howe...Lignin waste from the papermaking and biorefineries industry is a significantly promising renewable resource to prepare advanced carbon materials for diverse applications,such as the electrodes of supercapacitors;however,the improvement of their energy density remains a challenge.Here,we design a green and universal approach to prepare the composite electrode material,which is composed of lignin-phenolformaldehyde resins derived hierarchical porous carbon(LR-HPC)as conductive skeletons and the self-assembly manganese cobaltite(MnCo_(2)O_(4))nanocrystals as active sites.The synthesized C@MnCo_(2)O_(4)composite has an abundant porous structure and superior electronic conductivity,allowing for more charge/electron mass transfer channels and active sites for the redox reactions.The composite shows excellent electrochemical performance,such as the maximum specific capacitance of~726 mF cm^(-2)at 0.5 mV s^(-1),due to the significantly enhanced interactive interface between LR-HPC and MnCo_(2)O_(4)crystals.The assembled all-solid-state asymmetric supercapacitor,with the LR-HPC and C@MnCo_(2)O_(4)as cathode and anode,respectively,exhibits the highest volumetric energy density of 0.68 mWh cm^(-3)at a power density of 8.2 mW cm^(-3).Moreover,this device shows a high capacity retention ratio of~87.6%at 5 mA cm^(-2)after 5000 cycles.展开更多
In this work,phase and morphology-tuned MoO_(3) nanostructures are synthesized through a novel modified co-precipitation method,and their electrochemical properties are investigated.For the first time,such a simple su...In this work,phase and morphology-tuned MoO_(3) nanostructures are synthesized through a novel modified co-precipitation method,and their electrochemical properties are investigated.For the first time,such a simple surfactant-assisted synthesis process aided by minor temperature variations is reported which results in phase transition of the nanoparticles from h-MoO_(3) nano-rods to a-MoO_(3) nano-flakes.The nanostructures thus developed are highly porous and crystalline with significantly large specific surface area as compared to previous literature.The theoretical bandgap energy of the optimized sample calculated using Perdew-Zunger local density approximation(LDA) is in good agreement with the experimental findings.An overall structural,morphological,and surface-behavioural analysis predicts the electrochemical superiority in 2D a-MoO_(3).The cyclic voltammetry and galvano-potentiometry measurements of 2D a-MoO_(3) in the potential window of-0.6 V to +0.2 V present the highest pseudosupercapacitive response with a maximum specific capacitance of 829 F g^(-1)at 2 A g^(-1)as compared to h-MoO_(3) (452 F g^(-1)) and h@a-MoO_(3) (783 F g^(-1)).Thus,the MoO_(3) 2D nanostructures synthesized through our novel synthesis technique display excellent specific capacitance as compared to previous reported data.Additionally,a-MoO_(3) exhibits a galvanostatic charging-discharging cyclic stability of about 91%after 2000 cycles,indicating that it can serve as an excellent electrode material for supercapacitors.A solid-state asymmetric supercapacitor device is successfully constructed using a-MoO_(3) which can light up 4 red LEDs for 10 s.The specific energy density of the device reaches a maximum value of 36.3 W h kg^(-1)at the power density of 50 W kg^(-1).展开更多
A novel nano-composite of polyaniline/mesoporous carbon(PANI/CMK-3) was prepared with mesoporous carbon(CMK-3) serving as the support.Electrochemical asymmetric capacitors have been successfully designed by using ...A novel nano-composite of polyaniline/mesoporous carbon(PANI/CMK-3) was prepared with mesoporous carbon(CMK-3) serving as the support.Electrochemical asymmetric capacitors have been successfully designed by using PANI/CMK-3 composite and CMK-3 as positive and negative electrode,respectively.The results showed that the discharge capacity of the asymmetric capacitor could reach 87.4 F/g under the current density of 5 mA/cm^2 and cell voltage of 1.4 V.The energy density of the asymmetric capacitor was up to 23.8 Wh/kg with a power density of 206 W/kg.Furthermore,PANI/CMK-3-CMK-3 asymmetric capacitor using this PANI/CMK-3 nano-composite could be activated quickly and possess high charge-discharge efficiency.展开更多
A flexible asymmetric supercapacitor(ASC)based on a Co Al-layered double hydroxide(Co Al-LDH)electrode and a reduced graphene oxide(r GO) electrode was successfully fabricated. The Co Al-LDH electrode as a positive el...A flexible asymmetric supercapacitor(ASC)based on a Co Al-layered double hydroxide(Co Al-LDH)electrode and a reduced graphene oxide(r GO) electrode was successfully fabricated. The Co Al-LDH electrode as a positive electrode was synthesized by directly growing Co Al-LDH nanosheet arrays on a carbon cloth(CC)through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g^(-1)at a current density of1 A g^(-1). The r GO electrode as a negative electrode was synthesized by coating r GO on the CC via a simple dipcoating method and revealed a specific capacitance of110.0 F g^(-1)at a current density of 2 A g^(-1). Ultimately,the advanced ASC offered a broad voltage window(1.7 V)and exhibited a high superficial capacitance of1.77 F cm^(-2)at 2 m A cm^(-2)and a high energy density of0.71 m Wh cm^(-2)at a power density of 17.05 m W cm^(-2),along with an excellent cycle stability(92.9% capacitance retention over 8000 charge–discharge cycles).展开更多
Here we demonstrate the fabrication, electrochemical performance and application of an asymmetric supercapacitor (AS) device constructed with ss-Ni(OH)(2)/MWCNTs as positive electrode and KOH activated honeycomb-like ...Here we demonstrate the fabrication, electrochemical performance and application of an asymmetric supercapacitor (AS) device constructed with ss-Ni(OH)(2)/MWCNTs as positive electrode and KOH activated honeycomb-like porous carbon (K-PC) derived from banana fibers as negative electrode. Initially, the electrochemical performance of hydrothermally synthesized ss-Ni(OH)(2)/MWCNTs nanocomposite and K-PC was studied in a three-electrode system using 1 M KOH. These materials exhibited a specific capacitance (Cs) of 1327 Fig and 324 F/g respectively at a scan rate of 10 mV/s. Further, the AS device i.e., ss-Ni(OH)(2)/MWCNTs// K-PC in 1 M KOH solution, demonstrated a Cs of 156 F/g at scan rate of 10 mV/s in a broad cell voltage of 0-2.2 V. The device demonstrated a good rate capability by maintaining a Cs of 59 F/g even at high current density (25 A/g). The device also offered high energy density of 63 Wh/kg with maximum power density of 5.2 kW/kg. The AS device exhibited excellent cycle life with 100% capacitance retention at 5000th cycle at a high current density of 25 A/g. Two AS devices connected in series were employed for powering a pair of LEDs of different colors and also a mini fan. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays stru...Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo_2O_4 nanowires arrays, which were intimate contact with flexible carbon cloth(CC)by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo_2O_4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo_2O_4@CC electrode exhibits a high capacitance of 1183 mF cm^(-2) and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor(ASC)using NiCo_2O_4@CC as positive electrode and activated carbon cloth(ACC) as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^(-2)(12.5 F cm^(-3)), a high energy density of 0.24 mWh cm^(-2)(3.91 mWh cm^(-3)), as well as excellent cycle stability under different bending states.These remarkable results suggest that as-assembled NiCo_2O_4@CC//ACC ASC is a promising candidate in flexible energy storage applications.展开更多
Hydrous ruthenium oxide(h-Ru O) nanoparticles and its composite with multiwalled carbon nanotubes(h-Ru O/MWCNT) were synthesized by a simple hydrothermal method and proved to have potential application as hybrid super...Hydrous ruthenium oxide(h-Ru O) nanoparticles and its composite with multiwalled carbon nanotubes(h-Ru O/MWCNT) were synthesized by a simple hydrothermal method and proved to have potential application as hybrid supercapacitor material.The h-Ru Oand h-Ru O/MWCNT were characterized for their physico-chemical properties by PXRD,BET surface area,Raman,SEM-EDS and TEM techniques.The electrochemical performance of the materials were investigated,specific capacitance(Cs) of h-Ru Oand hRu O/MWCNT estimated by their cyclic voltammetric studies were found to be 604 and 1585 F/g respectively at a scan rate of 2 m V/s in the potential range 0–1.2 V.Further,this value was found to be nearly three times higher than that of pure h-Ru O.An asymmetric supercapacitor(AS) device was fabricated by employing h-Ru O/MWCNT as the positive electrode and activated carbon as the negative electrode.The device exhibited Cs of 61.8 F/g at a scan rate of 2 m V/s.Further,the device showed excellent long term stability for 20,000 cycles with 88% capacitance retention at a high current density of 25 A/g.展开更多
Superhydrophilic surfaces have been applied for supercapacitor;however,during energy storage reaction,how the wettability affects the process of electrochemical reaction specifically is still unclear.Herein,we demonst...Superhydrophilic surfaces have been applied for supercapacitor;however,during energy storage reaction,how the wettability affects the process of electrochemical reaction specifically is still unclear.Herein,we demonstrate superhydrophilic surface for promotion of electrochemical reactions by liquid affinity and further explain the mechanism,where the transition of the wettability state caused by the change in surface free energy is the main reason for the obvious increase in specific capacitance.Through citric acid assistance strategy,an intrinsically hydrophobic Ni(OH)_(2)thick nanosheets(HNHTNs,16 nm)can be transitioned into superhydrophilic Ni(OH)_(2)ultrathin nanosheets(SNHUNs,6.8 nm),where the water contact angle was 0°and the surface free energy increased from 8.6to 65.8 mN·m^(-1),implying superhydrophilicity.Compared with HNHTNs,the specific capacitance of SNHUNs is doubled:from 1230 F·g^(-1)(HNHTNs)to 2350 F·g^(-1)(2A·g^(-1))and,even at 20 A·g^(-1),from 833 F·g^(-1)(HNHTNs)to 1670 F·g^(-1).The asymmetric capacitors assembled by SNHUNs and activated carbon show 52.44 Wh·kg^(-1)at 160W·kg^(-1)and excellent stability with~90%retention after5000 cycles(~80%retention after 9500 cycles).The promotion of electrochemical performances is ascribed to the change of surface wettability caused by surface free energy,which greatly increase affinity of electrode to the surrounding liquid environment to reduce the interface resistance and optimize the electron transport path.展开更多
The search for wearable electronics has been attracted great efforts,there is an ever-growing demand for all-solid-state flexible energy storage devices.However,it is a challenge to obtain both positive and negative e...The search for wearable electronics has been attracted great efforts,there is an ever-growing demand for all-solid-state flexible energy storage devices.However,it is a challenge to obtain both positive and negative electrodes with excellent mechanical strength and match positive and negative charges to achieve high energy densities and operate voltages to satisfy practical application requirements.Here,flexible MXene(Ti_(3)C_(2)Tx)/cellulose nanofiber(CNF)composite film negative electrodes(MCNF)were fabricated with a vacuum filtration method,as well as positive electrodes(CP)by combining polyaniline(PANI)with carbon cloth(CC)using an in-situ polymerization method.Both positive and negative free-standing electrodes exhibited excellent electrochemical behavior and bendable/foldable flexibility.As a result,the all-pseudocapacitance asymmetric device of MCNF//CP assembled with charge-matched between anode and cathode achieves an extended voltage window of 1.5 V,high energy density of 30.6 Wh·kg^(−1)(1211 W·kg^(−1)),86%capacitance retention after 5000 cycles,the device maintains excellent bendability,simultaneously.This work will pave the way for the development of all-pseudocapacitive asymmetric supercapacitors(ASC)with simultaneously preeminent mechanical properties,high energy density,wide operating voltage window.展开更多
Electrochromic asymmetric supercapacitors(EASs), incorporating electrochromic and energy storage into one platform, are extremely desirable for next-generation civilian portable and smart electronic devices. However, ...Electrochromic asymmetric supercapacitors(EASs), incorporating electrochromic and energy storage into one platform, are extremely desirable for next-generation civilian portable and smart electronic devices. However, the crucial challenge of their fast self-discharge rate is often overlooked, although it plays an important role in practical application. Unfortunately, very limited research on EAS has focused on this critical problem. Here, an ultrathin all-inorganic EAS with excellent anti-self-discharge performance and superior electrochromic behavior is designed and manufactured by introducing a thin nanofunctional layer at the electrode/electrolyte interface. The prototype all-inorganic EAS exhibited a wide working voltage of 2.2 V, a high energy/power density(81.2mWh·cm^(-3)/0.688 W·cm^(-3)and 30.6 mWh·cm^(-3)/11.02W·cm^(-3)), along with outstanding electrochemical and electrochromic performance even at high temperatures.Remarkably, the introduced Ta2O5layer can efficiently prohibit the redistribution and diffusion of the movable ions at the fully charged state, endowing the all-inorganic EAS with a tardy self-discharge rate of 12.6 mV·g^(-1),which is an extremely low value when compared with previous reported research. Significantly, the ultrathin allinorganic EASs could also well maintain a slow self-discharge rate and their original electrochemical characteristics under various environmental temperatures. We envision that the novel strategy of electrode/electrolyte interface engineering can effectively deal with the severe self-discharge challenge of EAS, and provide more opportunities for their practical applications.展开更多
The combination of high-voltage windows and bending stability remains a challenge for supercapacitors.Here,we present an“advantage-complementary strategy”using sodium lignosulfonate as a pseudocapacitive molecule to...The combination of high-voltage windows and bending stability remains a challenge for supercapacitors.Here,we present an“advantage-complementary strategy”using sodium lignosulfonate as a pseudocapacitive molecule to regulate the spatial stacking pattern of graphene oxide and the interfacial architectures of graphene oxide and polyaniline.Flexible and sustainable sodium lignosulfonate-based electrodes are successfully developed,showing perfect bending stability and high electronic conductivity and specific capacitance(521 F·g^(−1)at 0.5 A·g^(−1)).Due to the resulting rational interfacial structure and stable ion-electron transport,the asymmetric supercapacitors provide a wide voltage window reaching 1.7 V,outstanding bending stability and high energy-power density of 83.87 Wh·kg^(−1)at 3.4 kW·kg^(−1).These properties are superior to other reported cases of asymmetric energy enrichment.The synergistic strategy of sodium lignosulfonate on graphene oxide and polyaniline is undoubtedly beneficial to advance the process for the construction of green flexible supercapacitors with remarkably wide voltage windows and excellent bending stability.展开更多
Constructing graphene-based heterostructures with large interfacial area is an efficient approach to enhance the electrochemical performance of supercapacitors but remains great challenges in their synthesis.Herein,a ...Constructing graphene-based heterostructures with large interfacial area is an efficient approach to enhance the electrochemical performance of supercapacitors but remains great challenges in their synthesis.Herein,a novel ultra-small amorphous Fe_(2)O_(3)nanodots/graphene heterostructure(a-Fe_(2)O_(3)NDs/RGO)aerogel was facilely synthesized via excessive metal-ion-induced self-assembly and subsequent calcination route using Prussian blue/graphene oxide(PB/GO)composite aerogel as precursors.The deliberately designed a-Fe_(2)O_(3)NDs/RGO heterostructure offers a highly interconnected porous conductive network,large heterostructure interfacial area,and plenty of accessible active sites,greatly facilitating the electron transfer,electrolyte diffusion,and pseudocapacitive reactions.The obtained a-Fe_(2)O_(3)NDs/RGO aerogel could be used as flexible free-standing electrodes after mechanical compression,which exhibited a significantly enhanced specific capacitance of 347.4 F·g^(-1)at 1 A·g^(-1),extraordinary rate capability of 184 F·g^(-1)at 10 A·g^(-1),and decent cycling stability.With the as-prepared a-Fe_(2)O_(3)NDs/RGO as negative electrodes and the Co_(3)O_(4)NDs/RGO as positive electrodes,an all-solid-state asymmetric supercapacitor(a-Fe_(2)O_(3)NDs/RGO//Co_(3)O_(4)NDs/RGO asymmetric supercapacitor(ASC))was assembled,which delivered a high specific capacitance of 69.1 F·g^(-1)at 1 A·g^(-1)and an impressive energy density of 21.6 W·h·k·g^(-1)at 750 W·k·g^(-1),as well as good cycling stability with a capacity retention of 94.3%after 5,000 cycles.This work provides a promising avenue to design high-performance graphene-based composite electrodes and profound inspiration for developing advanced flexible energy-storage devices.展开更多
The sandwich-like structure of reduced graphene oxide/polyaniline (RGO/PANI) hybrid electrode was prepared by electrochemical deposition. Both the voltage windows and electrolytes for electrochemical deposition of P...The sandwich-like structure of reduced graphene oxide/polyaniline (RGO/PANI) hybrid electrode was prepared by electrochemical deposition. Both the voltage windows and electrolytes for electrochemical deposition of PANI and RGO were optimized. In the composites, PANI nanofibers were anchored on the surface of the RGO sheets, which avoids the re-stacking of neighboring sheets. The R(;O/PANI composite electrode shows a high specific capacitance of 466 F/g at 2 mA/cm2 than that of previously reported RGO/PANI composites. Asymmetric flexible supercapacitors applying RGO/PANI as positive electrode and carbon fiber cloth as negative electrode can be cycled reversibly in the high-voltage region of 0-1.6 V and displays intriguing performance with a maximum specific capacitance of 35.5 mF cm^-2. Also, it delivers a high energy density of 45.5 mW h cm^-2 at power density of 1250 mW cm^-2. Furthermore, the asymmetric device exhibits an excellent long cycle life with 97.6Z initial capacitance retention after 5000 cycles. Such composite electrode has a great potential for applications in flexible electronics, roll-up display, and wearable devices.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.展开更多
High energy density and enhanced rate capability are highly sought-after for supercapacitors in today's mobile world.In this work,polyaniline/titanium carbide(MXene)(PANI/Ti3C2Tx)nanohybrid is synthesized through ...High energy density and enhanced rate capability are highly sought-after for supercapacitors in today's mobile world.In this work,polyaniline/titanium carbide(MXene)(PANI/Ti3C2Tx)nanohybrid is synthesized through a facile and cost-effective self-assembly of.one-dimensional(10)PANI nanofibers and two-dimensional(20)Ti3C2Tx nanosheets.PANl!Ti3C2Tx delivers greatly improved specific capacitance,ultrahigh rate capability(67%capacitance retention from 1 to 100 A·g^(-1))as well as good cycle stability.Electrochemical kinetic analysis reveals that PANI/Ti3C2Tx is featured with surface capacitance-dominated process and has a quasi-reversible kinetics at high scan rates,giving rise to an ultrahigh rate capability.By using PANl!Ti3C2Tx as positive electrode,an 1.8 V aqueous asymmetric supercapacitor(ASC)is successfully assembled,showing a maximum energy density of 50.8 Wh·kg^(-1)·(at 0.9 kW-kg-1)and a power density of 18 kW·kg^(-1)(at 26 Wh·kg^(-1)).Moreover,an 3.0 V organic ASC is also elaborately fabricated,·by using PANI/Ti3C2Tx,achieving an ultrahigh energy density of 67.2 Wh·kg^(-1)(at 1.5 kW·kg^(-1))and a power density of 30 kW·kg^(-1)·(at 26.8 Wh·kg^(-1)).The present work not only improves fundamental understanding of the structure-property relationship towards ultrahigh rate capability electrode materials,but also provides valuable guideline for the rational design of high-performance:energy storage devices with both high energy and power densities.展开更多
In this work,we report a high-performance self-standing supercapacitor electrode of mixed nickel manganese sulfides (NMSs)with a cracked-bark shape grown by one-step electrochemical deposition on activated carbon clot...In this work,we report a high-performance self-standing supercapacitor electrode of mixed nickel manganese sulfides (NMSs)with a cracked-bark shape grown by one-step electrochemical deposition on activated carbon cloth (ACC).The electrode possesses outstanding electrochemical properties,including a high specific capacitance of up to 3142.8 F g^(-1)at 1.0 A g^(-1),the high-rate performance (~1206.8 F g^(-1)at 60.0 A g^(-1)),and cycle stability (~92.3%capacitance retention after 8000 cycles at8 A g^(-1)).An asymmetric supercapacitor assembled using NMSs on ACC as the cathode,activated carbon on carbon cloth as the anode and 1.0 mol L;KOH as the electrolyte delivers a high energy density of 111.2 W h kg^(-1)at 800.0 W kg^(-1)and the prominent cycling performance of~93.2%capacitance retention after 10000 cycles at 5 A g^(-1)with the Columbic efficiency of around 100%during these 10000 cycles.The high performance and facile preparation indicate that the NMSs on ACC hold a huge potential as the electrode for supercapacitors.展开更多
Both MXene and zeolitic imidazolate framework(ZIF)derivatives are tend to agglomerate during the compound process,which adversely affects their electrochemical properties.To alleviate this phenomenon,fewlayer MXene wa...Both MXene and zeolitic imidazolate framework(ZIF)derivatives are tend to agglomerate during the compound process,which adversely affects their electrochemical properties.To alleviate this phenomenon,fewlayer MXene was stripped by mechanical method,and electrostatic self-assembly with ZIF-67 in the presence of cationic surfactants.Furthermore,CoNi_(2)S_(4)/MXene composite was synthesized by the facile hydrothermal reaction.CoNi_(2)S_(4)well retained the cube frame structure of the ZIF-67 with the sagging outer frame and rough surface.In the composite,CoNi_(2)S_(4)nanocubes were interlinked by MXene nanosheets,which can effectively improve the structural stability and make full use of the active surface.CoNi_(2)S_(4)/MXene composite electrode exhibits an outperforming specific capacitance(751 C·g^(-1)at 1 A·g^(-1)),far higher than that of pure CoNi2S4(600 C·g^(-1)at 1 A·g^(-1)).An asymmetric supercapacitor(CoNi_(2)S_(4)/MXene//reduced graphene oxide(RGO))assembling delivers high energy density of 33.8 Wh·kg^(-1)and excellent cycling performance.This study indicates the potential of MXene/ZIF derivatives in the application of supercapacitor.展开更多
An asymmetric supercapacitor (ASC) was assembled by using an activated carbon as positive electrode and WO3 nanowire as negative electrode, and its electrical performances were tested in voltage windows ranging from...An asymmetric supercapacitor (ASC) was assembled by using an activated carbon as positive electrode and WO3 nanowire as negative electrode, and its electrical performances were tested in voltage windows ranging from 0 to 1.5 V. A high specific capacitance of 51 Fog-1 could be achieved at the current density of 0.25 A·g-1 . Moreover, the ASC displays a good cycling stability with 86% of capacitance retention after 800 cycles, its energy density can be up to 11.9 Wh·kg-1 at the power density of 210 W·kg -1, and remains 7.7 Wh·kg-1 at a power density of 1250 W· kg-1. The excellent electrical performance is perhaps due to the crystal orientation of (001) planes for the WO3 nanowire, which favors the rapid reaction between W(VI) and H+ cations. This aqueous asymmetric WO3//AC supercapacitor is promising for practical applications due to its easy preparation of WO3.展开更多
Copper oxide has aroused great concern in energy storage fields due to its properties of high theoretical capacitance,low cost and mild toxicity.However,its wide application still remains challenges owing to its poor ...Copper oxide has aroused great concern in energy storage fields due to its properties of high theoretical capacitance,low cost and mild toxicity.However,its wide application still remains challenges owing to its poor electrical conductivity and unstable cycling life.Binder-free foam electrodes possess abundant porous structures and high specific surface area,which could get good contact with electrolyte.Herein,we demonstrate Ag nanoparticles decorated CuxO nanowires grown spontaneously on copper foam(CF)electrode for asymmetric supercapacitor.The skeleton structure of CF provides large amounts of active sites for the growth of CuxO nanowires.Moreover,Ag nanoparticles further decrease the internal resistance and enhance the electrochemical performance.Ag/CuxO/CF-40 electrode presents a high area specific capacitance of 1192 mF cm^(-2)at 2 mA cm^(-2)and the influence of surface capacitance-dominated process and diffusion-controlled process are discussed in detail.Besides,the energy density of the as-prepared asymmetric supercapacitor(ASC)reaches 46.32 mWh cm^(-2)at a power density of 3.00 mW cm^(-2).A 2V LED is lighted successfully by two ASC in series.This work provides a new strategy to prepare low internal resistance and binder-free flexible Ag/CuxO/CF electrode,which demonstrates a good potential application in flexible supercapacitors or other wearable electronic devices.展开更多
Fiber-shaped integrated devices are highly desirable for wearable and portable smart electronics,owing to their merits of lightweight,high flexibility,and wearability.However,how to effectively employ multifunctional ...Fiber-shaped integrated devices are highly desirable for wearable and portable smart electronics,owing to their merits of lightweight,high flexibility,and wearability.However,how to effectively employ multifunctional fibers in one integrated device that can simultaneously achieve energy storage and utilization is a major challenge.Herein,a set of multifunctional fibers all derived from vanadium metal-organic framework nanowires grown on carbon nanotube fiber(V-MOF NWs@CNT fiber)is demonstrated,which can be used for various energy storage and utilization applications.First,a fiber-shaped asymmetric supercapacitor(FASC)is fabricated based on the CoNi-layered double hydroxide nanosheets@vanadium oxide NWs@CNT fiber(CoNi-LDH NSs@V2O5 NWs@CNT fiber)as the positive electrode and vanadium nitride(VN)NWs@CNT fiber as the negative electrode.Benefiting from the outstanding compatibility of the functional materials,the FASC with a maximum working voltage of 1.7 V delivers a high-stack volumetric energy density of 11.27 mW·h/cm3.Then,a fiber-shaped integrated device is assembled by twisting a fiber-shaped piezoresistive sensor(FPS;VN NWs@CNT fiber also served as the highly sensitive material)and a FASC together,where the highperformance FASC can provide a stable and continuous output power for the FPS.Finally,the S-VOx NWs@CNT fiber(sulfur-doped vanadium oxide)electrode shows promising electrocatalytic performance for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),which is further constructed into a self-driven water-splitting unit with the integration of the FASCs.The present work demonstrates that the V-MOF NWs@CNTderived fibers have great potential for constructing wearable multifunctional integrated devices.展开更多
Constructing electrode materials with large capacity and good conductivity is an effective approach to improve the capacitor performance of asymmetric supercapacitors(ASCs).In this paper,ZnCo_(2)S_(4)core-shell nanosp...Constructing electrode materials with large capacity and good conductivity is an effective approach to improve the capacitor performance of asymmetric supercapacitors(ASCs).In this paper,ZnCo_(2)S_(4)core-shell nanospheres are constructed by two-step hydrothermal method.In order to improve the chemical activity of ZnCo_(2)S_(4),ZnCo_(2)S_(4)is activated using cetyltrimethylammonium bromide(CTAB).Then,MXene nanosheets are fixed on the surface of ZnCo_(2)S_(4)by electrostatic selfassembly method to improve the specific surface area of ZnCo_(2)S_(4)and MXene-wrapped ZnCo_(2)S_(4)composite is prepared in this work.Owing to the synergy effect between MXene nanosheets and ZnCo_(2)S_(4)core-shell nanospheres,the as-prepared composite displays fast ion transfer rate and charge/discharge process.The capacity of the MXenewrapped ZnCo_(2)S_(4)composite can reach 1072 F·g^(-1),which is far larger than that of ZnCo_(2)S_(4)(407 F·g^(-1))at 1 A·g^(-1).An ASC device is assembled,which delivers 1.7 V potential window and superior cyclic stability(95.41%capacitance retention).Furthermore,energy density of this device is up to 30.46 Wh·kg^(-1)at a power density of850 W·kg^(-1).The above results demonstrate that MXenewrapped ZnCo_(2)S_(4)composite has great application prospects in electrochemical energy storage field.展开更多
基金The authors gratefully acknowledge the financial support from the National Key R&D Program of China(2021YFC2101304)China Postdoctoral Science Foundation(BX2021041)。
文摘Lignin waste from the papermaking and biorefineries industry is a significantly promising renewable resource to prepare advanced carbon materials for diverse applications,such as the electrodes of supercapacitors;however,the improvement of their energy density remains a challenge.Here,we design a green and universal approach to prepare the composite electrode material,which is composed of lignin-phenolformaldehyde resins derived hierarchical porous carbon(LR-HPC)as conductive skeletons and the self-assembly manganese cobaltite(MnCo_(2)O_(4))nanocrystals as active sites.The synthesized C@MnCo_(2)O_(4)composite has an abundant porous structure and superior electronic conductivity,allowing for more charge/electron mass transfer channels and active sites for the redox reactions.The composite shows excellent electrochemical performance,such as the maximum specific capacitance of~726 mF cm^(-2)at 0.5 mV s^(-1),due to the significantly enhanced interactive interface between LR-HPC and MnCo_(2)O_(4)crystals.The assembled all-solid-state asymmetric supercapacitor,with the LR-HPC and C@MnCo_(2)O_(4)as cathode and anode,respectively,exhibits the highest volumetric energy density of 0.68 mWh cm^(-3)at a power density of 8.2 mW cm^(-3).Moreover,this device shows a high capacity retention ratio of~87.6%at 5 mA cm^(-2)after 5000 cycles.
文摘In this work,phase and morphology-tuned MoO_(3) nanostructures are synthesized through a novel modified co-precipitation method,and their electrochemical properties are investigated.For the first time,such a simple surfactant-assisted synthesis process aided by minor temperature variations is reported which results in phase transition of the nanoparticles from h-MoO_(3) nano-rods to a-MoO_(3) nano-flakes.The nanostructures thus developed are highly porous and crystalline with significantly large specific surface area as compared to previous literature.The theoretical bandgap energy of the optimized sample calculated using Perdew-Zunger local density approximation(LDA) is in good agreement with the experimental findings.An overall structural,morphological,and surface-behavioural analysis predicts the electrochemical superiority in 2D a-MoO_(3).The cyclic voltammetry and galvano-potentiometry measurements of 2D a-MoO_(3) in the potential window of-0.6 V to +0.2 V present the highest pseudosupercapacitive response with a maximum specific capacitance of 829 F g^(-1)at 2 A g^(-1)as compared to h-MoO_(3) (452 F g^(-1)) and h@a-MoO_(3) (783 F g^(-1)).Thus,the MoO_(3) 2D nanostructures synthesized through our novel synthesis technique display excellent specific capacitance as compared to previous reported data.Additionally,a-MoO_(3) exhibits a galvanostatic charging-discharging cyclic stability of about 91%after 2000 cycles,indicating that it can serve as an excellent electrode material for supercapacitors.A solid-state asymmetric supercapacitor device is successfully constructed using a-MoO_(3) which can light up 4 red LEDs for 10 s.The specific energy density of the device reaches a maximum value of 36.3 W h kg^(-1)at the power density of 50 W kg^(-1).
基金supported by the National Natural Science Foundation of China(No.50602020)the National Basic Research Program of China(No.2007CB216408).
文摘A novel nano-composite of polyaniline/mesoporous carbon(PANI/CMK-3) was prepared with mesoporous carbon(CMK-3) serving as the support.Electrochemical asymmetric capacitors have been successfully designed by using PANI/CMK-3 composite and CMK-3 as positive and negative electrode,respectively.The results showed that the discharge capacity of the asymmetric capacitor could reach 87.4 F/g under the current density of 5 mA/cm^2 and cell voltage of 1.4 V.The energy density of the asymmetric capacitor was up to 23.8 Wh/kg with a power density of 206 W/kg.Furthermore,PANI/CMK-3-CMK-3 asymmetric capacitor using this PANI/CMK-3 nano-composite could be activated quickly and possess high charge-discharge efficiency.
基金supported by National Natural Science Foundation of China(21376105 and 21576113)Foshan Innovative and Entepreneurial Research Team Program(No.2014IT100062)
文摘A flexible asymmetric supercapacitor(ASC)based on a Co Al-layered double hydroxide(Co Al-LDH)electrode and a reduced graphene oxide(r GO) electrode was successfully fabricated. The Co Al-LDH electrode as a positive electrode was synthesized by directly growing Co Al-LDH nanosheet arrays on a carbon cloth(CC)through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g^(-1)at a current density of1 A g^(-1). The r GO electrode as a negative electrode was synthesized by coating r GO on the CC via a simple dipcoating method and revealed a specific capacitance of110.0 F g^(-1)at a current density of 2 A g^(-1). Ultimately,the advanced ASC offered a broad voltage window(1.7 V)and exhibited a high superficial capacitance of1.77 F cm^(-2)at 2 m A cm^(-2)and a high energy density of0.71 m Wh cm^(-2)at a power density of 17.05 m W cm^(-2),along with an excellent cycle stability(92.9% capacitance retention over 8000 charge–discharge cycles).
基金supported by the Naval Research Board(NRB)Project Number:NRB-290/MAT/12-13
文摘Here we demonstrate the fabrication, electrochemical performance and application of an asymmetric supercapacitor (AS) device constructed with ss-Ni(OH)(2)/MWCNTs as positive electrode and KOH activated honeycomb-like porous carbon (K-PC) derived from banana fibers as negative electrode. Initially, the electrochemical performance of hydrothermally synthesized ss-Ni(OH)(2)/MWCNTs nanocomposite and K-PC was studied in a three-electrode system using 1 M KOH. These materials exhibited a specific capacitance (Cs) of 1327 Fig and 324 F/g respectively at a scan rate of 10 mV/s. Further, the AS device i.e., ss-Ni(OH)(2)/MWCNTs// K-PC in 1 M KOH solution, demonstrated a Cs of 156 F/g at scan rate of 10 mV/s in a broad cell voltage of 0-2.2 V. The device demonstrated a good rate capability by maintaining a Cs of 59 F/g even at high current density (25 A/g). The device also offered high energy density of 63 Wh/kg with maximum power density of 5.2 kW/kg. The AS device exhibited excellent cycle life with 100% capacitance retention at 5000th cycle at a high current density of 25 A/g. Two AS devices connected in series were employed for powering a pair of LEDs of different colors and also a mini fan. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金supported by the National Natural Science Foundation of China(Grant nos.51402324,51402325,51302281)
文摘Recently, binary metal oxides have been considerably researched for energy storage since it can provide higher electrical conductivity and electrochemical activity than single components. Besides, rational arrays structure design can effectively enhance the utilization of active material. In this article, we synthesis a porous NiCo_2O_4 nanowires arrays, which were intimate contact with flexible carbon cloth(CC)by a facile hydrothermal reaction and calcination treatment. The rational array structures of NiCo_2O_4 facilitate the diffusion of electrolyte and effectively increase the utilization of active material. The asobtained NiCo_2O_4@CC electrode exhibits a high capacitance of 1183 mF cm^(-2) and an outstanding capacitance retention of 90.4% after 3000 cycles. Furthermore, a flexible asymmetric supercapacitor(ASC)using NiCo_2O_4@CC as positive electrode and activated carbon cloth(ACC) as negative electrode was fabricated, which delivers a large capacitance of 750 mF cm^(-2)(12.5 F cm^(-3)), a high energy density of 0.24 mWh cm^(-2)(3.91 mWh cm^(-3)), as well as excellent cycle stability under different bending states.These remarkable results suggest that as-assembled NiCo_2O_4@CC//ACC ASC is a promising candidate in flexible energy storage applications.
基金financially supported by NRB-Naval Research Board(Project Number-NRB-290/MAT/12-13)
文摘Hydrous ruthenium oxide(h-Ru O) nanoparticles and its composite with multiwalled carbon nanotubes(h-Ru O/MWCNT) were synthesized by a simple hydrothermal method and proved to have potential application as hybrid supercapacitor material.The h-Ru Oand h-Ru O/MWCNT were characterized for their physico-chemical properties by PXRD,BET surface area,Raman,SEM-EDS and TEM techniques.The electrochemical performance of the materials were investigated,specific capacitance(Cs) of h-Ru Oand hRu O/MWCNT estimated by their cyclic voltammetric studies were found to be 604 and 1585 F/g respectively at a scan rate of 2 m V/s in the potential range 0–1.2 V.Further,this value was found to be nearly three times higher than that of pure h-Ru O.An asymmetric supercapacitor(AS) device was fabricated by employing h-Ru O/MWCNT as the positive electrode and activated carbon as the negative electrode.The device exhibited Cs of 61.8 F/g at a scan rate of 2 m V/s.Further,the device showed excellent long term stability for 20,000 cycles with 88% capacitance retention at a high current density of 25 A/g.
基金financially supported by the National Natural Science Foundation of China(Nos.22278349 and 62071413)Hebei Natural Science Foundation(Nos.B2020203013 and F2020203056)+4 种基金the Science and Technology Project of Hebei Education Department(No.QN2020137)Subsidy for Hebei Key Laboratory of Applied Chemistry after Operation Performance(No.22567616H)the Cultivation Project for Basic Research Innovation of Yanshan University(No.2021LGZD015)the Natural Science Foundation of Heilongjiang Province of China(No.LH2022B025)the Fundamental Research Funds for the Provincial Universities of Heilongjiang Province(No.KYYWF10236190104)。
文摘Superhydrophilic surfaces have been applied for supercapacitor;however,during energy storage reaction,how the wettability affects the process of electrochemical reaction specifically is still unclear.Herein,we demonstrate superhydrophilic surface for promotion of electrochemical reactions by liquid affinity and further explain the mechanism,where the transition of the wettability state caused by the change in surface free energy is the main reason for the obvious increase in specific capacitance.Through citric acid assistance strategy,an intrinsically hydrophobic Ni(OH)_(2)thick nanosheets(HNHTNs,16 nm)can be transitioned into superhydrophilic Ni(OH)_(2)ultrathin nanosheets(SNHUNs,6.8 nm),where the water contact angle was 0°and the surface free energy increased from 8.6to 65.8 mN·m^(-1),implying superhydrophilicity.Compared with HNHTNs,the specific capacitance of SNHUNs is doubled:from 1230 F·g^(-1)(HNHTNs)to 2350 F·g^(-1)(2A·g^(-1))and,even at 20 A·g^(-1),from 833 F·g^(-1)(HNHTNs)to 1670 F·g^(-1).The asymmetric capacitors assembled by SNHUNs and activated carbon show 52.44 Wh·kg^(-1)at 160W·kg^(-1)and excellent stability with~90%retention after5000 cycles(~80%retention after 9500 cycles).The promotion of electrochemical performances is ascribed to the change of surface wettability caused by surface free energy,which greatly increase affinity of electrode to the surrounding liquid environment to reduce the interface resistance and optimize the electron transport path.
基金the National Natural Science Foundation of China(No.32201491)Major projects of Natural Science Foundation of Jiangsu(No.18KJA220002)China Postdoctoral Science Foundation:Special Program(No.2017T100313).
文摘The search for wearable electronics has been attracted great efforts,there is an ever-growing demand for all-solid-state flexible energy storage devices.However,it is a challenge to obtain both positive and negative electrodes with excellent mechanical strength and match positive and negative charges to achieve high energy densities and operate voltages to satisfy practical application requirements.Here,flexible MXene(Ti_(3)C_(2)Tx)/cellulose nanofiber(CNF)composite film negative electrodes(MCNF)were fabricated with a vacuum filtration method,as well as positive electrodes(CP)by combining polyaniline(PANI)with carbon cloth(CC)using an in-situ polymerization method.Both positive and negative free-standing electrodes exhibited excellent electrochemical behavior and bendable/foldable flexibility.As a result,the all-pseudocapacitance asymmetric device of MCNF//CP assembled with charge-matched between anode and cathode achieves an extended voltage window of 1.5 V,high energy density of 30.6 Wh·kg^(−1)(1211 W·kg^(−1)),86%capacitance retention after 5000 cycles,the device maintains excellent bendability,simultaneously.This work will pave the way for the development of all-pseudocapacitive asymmetric supercapacitors(ASC)with simultaneously preeminent mechanical properties,high energy density,wide operating voltage window.
基金financially supported by the National Natural Science Foundation of China (Nos. 62205311, 52073007, 61875005 and 52011540389)the Fundamental Research Program of Shanxi Province (No. 202103021223177)。
文摘Electrochromic asymmetric supercapacitors(EASs), incorporating electrochromic and energy storage into one platform, are extremely desirable for next-generation civilian portable and smart electronic devices. However, the crucial challenge of their fast self-discharge rate is often overlooked, although it plays an important role in practical application. Unfortunately, very limited research on EAS has focused on this critical problem. Here, an ultrathin all-inorganic EAS with excellent anti-self-discharge performance and superior electrochromic behavior is designed and manufactured by introducing a thin nanofunctional layer at the electrode/electrolyte interface. The prototype all-inorganic EAS exhibited a wide working voltage of 2.2 V, a high energy/power density(81.2mWh·cm^(-3)/0.688 W·cm^(-3)and 30.6 mWh·cm^(-3)/11.02W·cm^(-3)), along with outstanding electrochemical and electrochromic performance even at high temperatures.Remarkably, the introduced Ta2O5layer can efficiently prohibit the redistribution and diffusion of the movable ions at the fully charged state, endowing the all-inorganic EAS with a tardy self-discharge rate of 12.6 mV·g^(-1),which is an extremely low value when compared with previous reported research. Significantly, the ultrathin allinorganic EASs could also well maintain a slow self-discharge rate and their original electrochemical characteristics under various environmental temperatures. We envision that the novel strategy of electrode/electrolyte interface engineering can effectively deal with the severe self-discharge challenge of EAS, and provide more opportunities for their practical applications.
基金This work was supported by the Natural Science Foundation of Guangxi(Grant No.2018GXNSFBA138025)the National Natural Science Foundation of China(Grant No.32171720).
文摘The combination of high-voltage windows and bending stability remains a challenge for supercapacitors.Here,we present an“advantage-complementary strategy”using sodium lignosulfonate as a pseudocapacitive molecule to regulate the spatial stacking pattern of graphene oxide and the interfacial architectures of graphene oxide and polyaniline.Flexible and sustainable sodium lignosulfonate-based electrodes are successfully developed,showing perfect bending stability and high electronic conductivity and specific capacitance(521 F·g^(−1)at 0.5 A·g^(−1)).Due to the resulting rational interfacial structure and stable ion-electron transport,the asymmetric supercapacitors provide a wide voltage window reaching 1.7 V,outstanding bending stability and high energy-power density of 83.87 Wh·kg^(−1)at 3.4 kW·kg^(−1).These properties are superior to other reported cases of asymmetric energy enrichment.The synergistic strategy of sodium lignosulfonate on graphene oxide and polyaniline is undoubtedly beneficial to advance the process for the construction of green flexible supercapacitors with remarkably wide voltage windows and excellent bending stability.
基金the fund for post-doctoral program of Henan University to Z.H.C.(No.FJ3050A0670001)the National Natural Science Foundation of China(Nos.51672172,51872186).
文摘Constructing graphene-based heterostructures with large interfacial area is an efficient approach to enhance the electrochemical performance of supercapacitors but remains great challenges in their synthesis.Herein,a novel ultra-small amorphous Fe_(2)O_(3)nanodots/graphene heterostructure(a-Fe_(2)O_(3)NDs/RGO)aerogel was facilely synthesized via excessive metal-ion-induced self-assembly and subsequent calcination route using Prussian blue/graphene oxide(PB/GO)composite aerogel as precursors.The deliberately designed a-Fe_(2)O_(3)NDs/RGO heterostructure offers a highly interconnected porous conductive network,large heterostructure interfacial area,and plenty of accessible active sites,greatly facilitating the electron transfer,electrolyte diffusion,and pseudocapacitive reactions.The obtained a-Fe_(2)O_(3)NDs/RGO aerogel could be used as flexible free-standing electrodes after mechanical compression,which exhibited a significantly enhanced specific capacitance of 347.4 F·g^(-1)at 1 A·g^(-1),extraordinary rate capability of 184 F·g^(-1)at 10 A·g^(-1),and decent cycling stability.With the as-prepared a-Fe_(2)O_(3)NDs/RGO as negative electrodes and the Co_(3)O_(4)NDs/RGO as positive electrodes,an all-solid-state asymmetric supercapacitor(a-Fe_(2)O_(3)NDs/RGO//Co_(3)O_(4)NDs/RGO asymmetric supercapacitor(ASC))was assembled,which delivered a high specific capacitance of 69.1 F·g^(-1)at 1 A·g^(-1)and an impressive energy density of 21.6 W·h·k·g^(-1)at 750 W·k·g^(-1),as well as good cycling stability with a capacity retention of 94.3%after 5,000 cycles.This work provides a promising avenue to design high-performance graphene-based composite electrodes and profound inspiration for developing advanced flexible energy-storage devices.
基金supported by the Qing Lan Project of Jiangsu Provincethe Natural Science Foundation of Jiangsu Province (BK20161289)+4 种基金the Natural Science Foundation of Higher Education of Jiangsu Province (17KJB610009)the Research Innovation Program for College Graduates and Students of Jiangsu Province (KYZZ15 0043)the Foundation of Nantong Vocational University (1512102)the College Students Innovation and Entrepreneurship Training Program of Jiangsu Province (201612684001Y)333 Talents Program of Jiangsu Province (BRA2016195)
文摘The sandwich-like structure of reduced graphene oxide/polyaniline (RGO/PANI) hybrid electrode was prepared by electrochemical deposition. Both the voltage windows and electrolytes for electrochemical deposition of PANI and RGO were optimized. In the composites, PANI nanofibers were anchored on the surface of the RGO sheets, which avoids the re-stacking of neighboring sheets. The R(;O/PANI composite electrode shows a high specific capacitance of 466 F/g at 2 mA/cm2 than that of previously reported RGO/PANI composites. Asymmetric flexible supercapacitors applying RGO/PANI as positive electrode and carbon fiber cloth as negative electrode can be cycled reversibly in the high-voltage region of 0-1.6 V and displays intriguing performance with a maximum specific capacitance of 35.5 mF cm^-2. Also, it delivers a high energy density of 45.5 mW h cm^-2 at power density of 1250 mW cm^-2. Furthermore, the asymmetric device exhibits an excellent long cycle life with 97.6Z initial capacitance retention after 5000 cycles. Such composite electrode has a great potential for applications in flexible electronics, roll-up display, and wearable devices.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.
基金support of the National Natural Science Foundation of China(No.21773116)the Specialized Research Fund for the Doctoral Program of Higher Education(SRFDP,20130091110010)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK2011438)the National Science Fund for Talent Training in Basic Science(No.J1103310)the Modern Analysis Center of Nanjing University and the Program B for Outstanding PhD Candidate of Nanjing University.
文摘High energy density and enhanced rate capability are highly sought-after for supercapacitors in today's mobile world.In this work,polyaniline/titanium carbide(MXene)(PANI/Ti3C2Tx)nanohybrid is synthesized through a facile and cost-effective self-assembly of.one-dimensional(10)PANI nanofibers and two-dimensional(20)Ti3C2Tx nanosheets.PANl!Ti3C2Tx delivers greatly improved specific capacitance,ultrahigh rate capability(67%capacitance retention from 1 to 100 A·g^(-1))as well as good cycle stability.Electrochemical kinetic analysis reveals that PANI/Ti3C2Tx is featured with surface capacitance-dominated process and has a quasi-reversible kinetics at high scan rates,giving rise to an ultrahigh rate capability.By using PANl!Ti3C2Tx as positive electrode,an 1.8 V aqueous asymmetric supercapacitor(ASC)is successfully assembled,showing a maximum energy density of 50.8 Wh·kg^(-1)·(at 0.9 kW-kg-1)and a power density of 18 kW·kg^(-1)(at 26 Wh·kg^(-1)).Moreover,an 3.0 V organic ASC is also elaborately fabricated,·by using PANI/Ti3C2Tx,achieving an ultrahigh energy density of 67.2 Wh·kg^(-1)(at 1.5 kW·kg^(-1))and a power density of 30 kW·kg^(-1)·(at 26.8 Wh·kg^(-1)).The present work not only improves fundamental understanding of the structure-property relationship towards ultrahigh rate capability electrode materials,but also provides valuable guideline for the rational design of high-performance:energy storage devices with both high energy and power densities.
基金supported by the Natural Science Foundation of Gansu,China(Grant No.20JR10RA611)。
文摘In this work,we report a high-performance self-standing supercapacitor electrode of mixed nickel manganese sulfides (NMSs)with a cracked-bark shape grown by one-step electrochemical deposition on activated carbon cloth (ACC).The electrode possesses outstanding electrochemical properties,including a high specific capacitance of up to 3142.8 F g^(-1)at 1.0 A g^(-1),the high-rate performance (~1206.8 F g^(-1)at 60.0 A g^(-1)),and cycle stability (~92.3%capacitance retention after 8000 cycles at8 A g^(-1)).An asymmetric supercapacitor assembled using NMSs on ACC as the cathode,activated carbon on carbon cloth as the anode and 1.0 mol L;KOH as the electrolyte delivers a high energy density of 111.2 W h kg^(-1)at 800.0 W kg^(-1)and the prominent cycling performance of~93.2%capacitance retention after 10000 cycles at 5 A g^(-1)with the Columbic efficiency of around 100%during these 10000 cycles.The high performance and facile preparation indicate that the NMSs on ACC hold a huge potential as the electrode for supercapacitors.
基金financially supported by the Fundamental Research Funds for the Central Universities (No. 2019XKQYMS16)
文摘Both MXene and zeolitic imidazolate framework(ZIF)derivatives are tend to agglomerate during the compound process,which adversely affects their electrochemical properties.To alleviate this phenomenon,fewlayer MXene was stripped by mechanical method,and electrostatic self-assembly with ZIF-67 in the presence of cationic surfactants.Furthermore,CoNi_(2)S_(4)/MXene composite was synthesized by the facile hydrothermal reaction.CoNi_(2)S_(4)well retained the cube frame structure of the ZIF-67 with the sagging outer frame and rough surface.In the composite,CoNi_(2)S_(4)nanocubes were interlinked by MXene nanosheets,which can effectively improve the structural stability and make full use of the active surface.CoNi_(2)S_(4)/MXene composite electrode exhibits an outperforming specific capacitance(751 C·g^(-1)at 1 A·g^(-1)),far higher than that of pure CoNi2S4(600 C·g^(-1)at 1 A·g^(-1)).An asymmetric supercapacitor(CoNi_(2)S_(4)/MXene//reduced graphene oxide(RGO))assembling delivers high energy density of 33.8 Wh·kg^(-1)and excellent cycling performance.This study indicates the potential of MXene/ZIF derivatives in the application of supercapacitor.
基金Financial support from the Distinguished Young Scientists Program of the National Natural Science Foundation of China (No. 51425301), the Science and Technology Commission of Shanghai Municipality (Nos. 12JC1401200 and 14520721800) and the Hunan Provincial Natural Science Foundation of China (No. 143J2081) is gratefully appreciated.
文摘An asymmetric supercapacitor (ASC) was assembled by using an activated carbon as positive electrode and WO3 nanowire as negative electrode, and its electrical performances were tested in voltage windows ranging from 0 to 1.5 V. A high specific capacitance of 51 Fog-1 could be achieved at the current density of 0.25 A·g-1 . Moreover, the ASC displays a good cycling stability with 86% of capacitance retention after 800 cycles, its energy density can be up to 11.9 Wh·kg-1 at the power density of 210 W·kg -1, and remains 7.7 Wh·kg-1 at a power density of 1250 W· kg-1. The excellent electrical performance is perhaps due to the crystal orientation of (001) planes for the WO3 nanowire, which favors the rapid reaction between W(VI) and H+ cations. This aqueous asymmetric WO3//AC supercapacitor is promising for practical applications due to its easy preparation of WO3.
基金supported by Key R&D Program of Zhenjiang(GY2018016).
文摘Copper oxide has aroused great concern in energy storage fields due to its properties of high theoretical capacitance,low cost and mild toxicity.However,its wide application still remains challenges owing to its poor electrical conductivity and unstable cycling life.Binder-free foam electrodes possess abundant porous structures and high specific surface area,which could get good contact with electrolyte.Herein,we demonstrate Ag nanoparticles decorated CuxO nanowires grown spontaneously on copper foam(CF)electrode for asymmetric supercapacitor.The skeleton structure of CF provides large amounts of active sites for the growth of CuxO nanowires.Moreover,Ag nanoparticles further decrease the internal resistance and enhance the electrochemical performance.Ag/CuxO/CF-40 electrode presents a high area specific capacitance of 1192 mF cm^(-2)at 2 mA cm^(-2)and the influence of surface capacitance-dominated process and diffusion-controlled process are discussed in detail.Besides,the energy density of the as-prepared asymmetric supercapacitor(ASC)reaches 46.32 mWh cm^(-2)at a power density of 3.00 mW cm^(-2).A 2V LED is lighted successfully by two ASC in series.This work provides a new strategy to prepare low internal resistance and binder-free flexible Ag/CuxO/CF electrode,which demonstrates a good potential application in flexible supercapacitors or other wearable electronic devices.
基金Key Research and Development Program of Shaanxi,Grant/Award Number:2020KWZ-001Innovation Foundation for Doctoral Dissertation of Northwestern Polytechnical University,Grant/Award Number:CX2021042National Natural Science Foundation of China,Grant/Award Number:51902265。
文摘Fiber-shaped integrated devices are highly desirable for wearable and portable smart electronics,owing to their merits of lightweight,high flexibility,and wearability.However,how to effectively employ multifunctional fibers in one integrated device that can simultaneously achieve energy storage and utilization is a major challenge.Herein,a set of multifunctional fibers all derived from vanadium metal-organic framework nanowires grown on carbon nanotube fiber(V-MOF NWs@CNT fiber)is demonstrated,which can be used for various energy storage and utilization applications.First,a fiber-shaped asymmetric supercapacitor(FASC)is fabricated based on the CoNi-layered double hydroxide nanosheets@vanadium oxide NWs@CNT fiber(CoNi-LDH NSs@V2O5 NWs@CNT fiber)as the positive electrode and vanadium nitride(VN)NWs@CNT fiber as the negative electrode.Benefiting from the outstanding compatibility of the functional materials,the FASC with a maximum working voltage of 1.7 V delivers a high-stack volumetric energy density of 11.27 mW·h/cm3.Then,a fiber-shaped integrated device is assembled by twisting a fiber-shaped piezoresistive sensor(FPS;VN NWs@CNT fiber also served as the highly sensitive material)and a FASC together,where the highperformance FASC can provide a stable and continuous output power for the FPS.Finally,the S-VOx NWs@CNT fiber(sulfur-doped vanadium oxide)electrode shows promising electrocatalytic performance for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER),which is further constructed into a self-driven water-splitting unit with the integration of the FASCs.The present work demonstrates that the V-MOF NWs@CNTderived fibers have great potential for constructing wearable multifunctional integrated devices.
基金financially supported by the Fundamental Research Funds for the Central Universities (No. 2019XKQYMS16)
文摘Constructing electrode materials with large capacity and good conductivity is an effective approach to improve the capacitor performance of asymmetric supercapacitors(ASCs).In this paper,ZnCo_(2)S_(4)core-shell nanospheres are constructed by two-step hydrothermal method.In order to improve the chemical activity of ZnCo_(2)S_(4),ZnCo_(2)S_(4)is activated using cetyltrimethylammonium bromide(CTAB).Then,MXene nanosheets are fixed on the surface of ZnCo_(2)S_(4)by electrostatic selfassembly method to improve the specific surface area of ZnCo_(2)S_(4)and MXene-wrapped ZnCo_(2)S_(4)composite is prepared in this work.Owing to the synergy effect between MXene nanosheets and ZnCo_(2)S_(4)core-shell nanospheres,the as-prepared composite displays fast ion transfer rate and charge/discharge process.The capacity of the MXenewrapped ZnCo_(2)S_(4)composite can reach 1072 F·g^(-1),which is far larger than that of ZnCo_(2)S_(4)(407 F·g^(-1))at 1 A·g^(-1).An ASC device is assembled,which delivers 1.7 V potential window and superior cyclic stability(95.41%capacitance retention).Furthermore,energy density of this device is up to 30.46 Wh·kg^(-1)at a power density of850 W·kg^(-1).The above results demonstrate that MXenewrapped ZnCo_(2)S_(4)composite has great application prospects in electrochemical energy storage field.