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The key challenges and future opportunities of electrochemical capacitors

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Journal of Energy Chemistry 2023年第1期76卷 459-461,I0012页

作者： Fangyan Liu Xinliang Feng Zhong-Shuai Wu State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina Center for Advancing Electronics Dresden(Cfaed)and Faculty of Chemistry and Food Chemistry Technische Universitat Dresden01062 DresdenGermany Department of Synthetic Materials and Functional Devices Max Planck Institute of Microstructure PhysicsD-06120 Halle(Saale)Germany

electrochemical capacitors(ECs)with unique merits of fast charge/discharge rate and long cyclability are one of the representative electrochemical energy storage systems,possessing wide applications in power electroni... 详细信息

关键词： electrochemical capacitors Electrical double layer capacitors Pseudocapacitors Li-ion capacitors Microscale electrochemical capacitors

Pseudocapacitive materials for electrochemical capacitors:from rational synthesis to capacitance optimization

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National Science Review 2017年第1期4卷 71-90页

作者： Jie Wang Shengyang Dong Bing Ding Ya Wang Xiaodong Hao Hui Dou Yongyao Xia Xiaogang Zhang Key Laboratory of Materials and Technologies for Energy Conversion College of Material Science & EngineeringNanjing University of Aeronautics and Astronautics Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials Institute of New Energy and iChEM (Collaborative Innovation Center of Chemistry for Energy Materials)Fudan University

Among various energy-storage devices,electrochemical capacitors(ECs) are prominent power provision but show relatively low energy density.One way to increase the energy density of ECs is to move from carbon-based electric double-layer capacitors to pseudocapacitors,which manifest much higher capacitance.However,compared with carbon materials,the pseudocapacitive electrodes sufer from high resistance for electron and/or ion transfer,signiicantly restricting their capacity,rate capability and cyclability.Rational design of electrode materials ofers opportunities to optimize their electrochemical performance,leading to devices with high energy density while maintaining high power density.his paper reviews the diferent approaches of electrodes striving to advance the energy and power density of ECs.

关键词： electrochemical capacitors pseudocapacitive electrode energy density power density cycle stability

Nanosized Nickel Oxides Derived from the Citrate Gel Process and Performances for electrochemical capacitors

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Journal of Wuhan University of Technology(Materials Science) 2007年第2期22卷 179-182页

作者：沈湘黔 School of Materials Science and Engineering Jiangsu University

Nanosized nickel oxide powders were prepared by thermal decomposition of the nickel citrate gel precursors. The thermal decomposition and powder materials derived from calcination of these gel precursors with various ratios of citric acid （CA） to nickel at different temperatures and times were characterized by thermal analysis （TG/DTA）, scanning electron microscopy （SEM）, x-ray diffraction （XRD）, and measurement of specific surface area （BET） with porosity analyses. The optimized processing conditions of calcination temperature 400℃ for 1 hour with the CA/Ni ratio of 1.2, were determined to produce the nanosized nickel oxide pow- ders with a high specific surface area of 181 m^2/g, nanometer particle sizes of 15-25 nm, micro-pore diameter distribution between 4-10 nm. The capacitance characteristics of the nanosized nickel oxide electrode in various concentrations of KOH solutions were studied by the cyclic voltammetry （CV） exhibiting both a double-layer capacitance and a faradaic pseudocapacitance. The nanosized nickel oxide electrode shows a high cyclic stability and is promising for high performance electrochemical capacitors.

关键词： citrate gel process nanosized nickel oxide electrode electrochemical capacitors capaci- tance characteristics

Promising Porous Carbon Derived from Waste Biomass for Dye-Sensitized Solar Cells and electrochemical capacitors

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Promising Porous Carbon Derived from Waste Biomass for Dye-S...

Review on supercapacitors:Technologies and performance evaluation

第四届新型太阳能电池学术研讨会

作者：王晓东 Wen Fang Chen Zhang Xue Li Ziqi Wang Hongfei Xu Yangliang Zhang 云斯宁西安建筑科技大学材料与矿资学院功能材料研究所

Recently, many efforts have been made to replace Pt using carbonaceous materials such as carbon nanotubes, porous carbon, graphe, carbon fibers, and carbon black in the counter electrodes(CEs) of dye-sensitized solar cells(DSSCs) and electrode materials(EMs) of electrochemical capacitors(ECs) owing to their low cost, good electrochemical performance and high conductivity.A simple and low cost method to synthesis porous carbon materials from waste biomass was developed.Three kinds of porous carbon(hydrochar, pyrolytic carbon and activated carbon) materials have been used as CEs of DSSCs and EMs of ECs in this work.These electrodes all showed an excellent electrocatalytic activity for the reduction of I to I in the electrolyte, achieving wonderful conversion efficiency.Especially, the activated carbon exhibited a rather high electrochemical storage capacity with a specific capacitance of 365 F g at 1 A g and also revealed a high rate capability with capacitance retention of 81% even at 20 A g as well as a high cycling stability with about 97% maintained after 5,000 charge-discharge cycles.

关键词： Dye-sensitized solar cells electrochemical capacitors carbonation waste biomass

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Journal of Energy Chemistry 2021年第8期30卷 276-291,I0006页

作者： Jingyuan Zhao Andrew F.Burke Institute of Transportation Studies University of California-Davis95616 DavisUSA Computer Science and Technology Shenzhen Institutes of Advanced TechnologyChinese Academy of Sciences518118 ShenzhenChina

The development of electrochemical capacitors(i.***.supercapacitors)have attracted a lot of attention in recent years because of the increasing demand for efficient,high-power energy storage.electrochemical capacitors(ECs)are particularly attractive for transportation and renewable energy generation applications,taking advantage of their superior power capability and outstanding cycle life.Over the past decade,various advanced electrode materials and cell design are being studied to improve the energy density of ECs.Hybrid Li-ion capacitors and pseudo-capacitors that utilize fast surface redox reactions of metal oxide and doped polymers are the prime candidates being considered.This paper is concerned with the metrics being used to describe the performance of ECs and how the metrics are evaluated by testing devices and how the data from the testing are best interpreted.Emphasize is on relating testing of advanced ECs using materials more complex than activated carbons to testing electric double-layer capacitors(EDLCs)using carbon in both electrodes.A second focus of the paper is projecting the potential of the advanced materials and ionic liquid electrolytes for the development of complete EC cells having an energy density more than a factor of ten greater the energy density of the EDLC devices currently on the market.This potential was evaluated by calculating the performance(energy and power)of a series of ECs that utilize the advanced materials that have been studied by electrochemists over the past 10-15 years.The capacitance and resistance of the advanced ECs were calculated utilizing specific capacitance(F/g or F/cm^(3))and porosity data for the electrode materials and ionic conductivity of the electrolytes.It was concluded that hybrid ECs can be developed with energy densities of at least 50 Wh/kg,70 Wh/L with efficient power greater than 3 k W/kg.Continued research on micro-porous carbons with specific capacitance of 200 F/g and greater is needed.to achieve these EC performance goals.

关键词： electrochemical capacitors Metrics Evaluation Cell design Applications

Hybrid aqueous capacitors with improved energy/power performance

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Progress in Natural Science:Materials International 2015年第6期25卷 642-649页

作者： Jakub Menzel Krzysztof Fic Elzbieta Frackowiak Poznan University of Technology Institute of Chemistry and Technical Electrochemistry

This work reports on a high-voltage,hybrid capacitor involving two separate redox reactions.Aqueous solutions of Mg(NO3)2and KI have been used for negative and positive electrode,respectively.Adjusting p H ? 2 for electrode( t) with KI solution and modifying Mg(NO3)2solution to p H ? 9 for negative side play a crucial role for a stable long-term operation of capacitor at enhanced voltage.A benefit from such a construction is a pseudocapacitive contribution from hydrogen sorption reaction on the negative electrode and high iodine/iodide activity on the positive electrode,enhancing the energy with no remarkable impact on the power profile.Proposed solution allows a high voltage(1.8 V) to be reached and thereby high power and energy performance( 20 W h/kg at 1 k W/kg) to be obtained.High long-term stability has been confirmed by floating and galvanostatic tests.

关键词： electrochemical capacitors High-voltage systems Hybrid systems Carbon electrodes Aqueous systems Neutral electrolytes

Carbon/carbon supercapacitors

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Journal of Energy Chemistry 2013年第2期22卷 226-240页

作者： Elzbieta Frackowiak Qamar Abbas Franois Bguin Institute of Chemistry and Technical Electrochemistry Poznan University of Technology Piotrowo 3 60-965 Poznan Poland

Supercapacitors, or electrochemical capacitors, are a power storage system applied for harvesting energy and delivering pulses during short periods of time. The commercially available technology is based on charging an electrical double-layer （EDL）, and using high surface area carbon electrodes in an organic electrolyte. This review first presents the state-of-the-art on EDL capacitors, with the objective to better understand their operating principles and to improve their performance. In particular, it is shown that capacitance might be enhanced for carbons having subnanometric pores where ions of the electrolyte are distorted and partly desolvated. Then, strategies tbr using environment l^endly aqueous electrolytes are presented. In this case, the capacitance can be enhanced through pseudo-faradaic contributions involving i） surface functional groups on carbons, ii） hydrogen electrosorption, and iii） redox reactions at the electrode/electrolyte interface. The most promising system is based on the use of aqueous alkali sulfate as electrolyte allowing voltages as high as 2 V to be reached, due to the high overpotential for di-hydrogen evolution at the negative electrode.

关键词： supercapacitors electrochemical capacitors porous carbons electrolytes pore size pseudocapacitance

SiO2 stabilizes electrochemically active nitrogen in few-layer carbon electrodes of extraordinary capacitance

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Journal of Energy Chemistry 2020年第10期29卷 179-188页

作者： Feng Xu Tianquan Lin Jian Huang I-Wei Chen Fuqiang Huang State Key Laboratory of High Performance Ceramics and Superfine Microstructure.Shanghai Institute of Ceramics Chinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences 19 Yuquan RoadBeijing 100049China Department of Materials Science and Engineering University of PennsylvaniaPhiladelphiaPA 19104USA College of Chemistry and Molecular Engineering Peking UniversityBeijing 100871China

Pyrrolic and pyridinic N dopants can dramatically increase the electrochemical activities of carbon and conducting polymers.Although N-doped conducting polymers suffer from rapid degradation,their carbon counterpart of extraordinary capacitance has remarkable rate performance and cycling endurance thanks to carbon’s excellent electrical conductivity.But high nitrogen content and high electrical conductivity are difficult to achieve in a high-surface-area carbon,because the high chemical vapor deposition(CVD)temperature required for obtaining high conductivity also destabilizes under-coordinated pyrrolic and pyridinic nitrogen and tends to lower the surface area.Here we resolve this dilemma by using SiO2 as an effective N-fixation additive,which stabilizes the N-rich nano few-layer sp2-carbon construct in1000℃CVD.This enables a scalable sol-gel/CVD fabrication process for few-layer carbon electrodes of extraordinary capacitance(690 F g^-1).The electrodes have excellent rate performance and can maintain90%of their initial capacitance after 30,000 cycles,thus potentially suitable for practical applications.

关键词： electrochemical capacitors Carbon electrodes Extraordinary capacitance SiO2 stabilized nitrogen

Fabrication and electrochemical performance of graphene-ZnO nanocomposites

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Chinese Physics B 2014年第5期23卷 499-504页

作者：李振鹏门传玲王婉曹军 School of Energy and Power Engineering University of Shanghai for Science and Technology

Graphene-ZnO nanocomposites were synthesized successfully through a one-step solvothermal approach. The mor-phology, structure, and composition of the prepared nanocomposites were investigated by scanning electron microscopy （SEM）, transmission electron microscope （TEM）, laser micro Raman spectroscopy, and Fourier transform infra-red spec-troscopy （FT-IR）. The outcomes confirmed that this approach is comparatively steady, practicable, and operable compared with other reported methods. The electrochemical performance of the graphene-ZnO electrodes was analyzed through cyclic voltammetry, altering-current （AC） impedance, and chronopotentiometry tests. The graphene-ZnO electrodes exhib-ited an improved electrode performance with higher specific capacitance （115 F·g^-1 ）, higher electrochemical stability, and higher energy density than the graphene electrodes and most reported graphene-ZnO electrodes. Graphene-ZnO nanocom-posites have a steady reversible charge/discharge behavior, which makes them promising candidates for electrochemical capacitors （ECs）.

关键词： graphene-ZnO nanocomposites electrochemical performance electrochemical capacitors