High-energy sodium-ion hybrid capacitors through nanograin-boundary-induced pseudocapacitance of Co_(3)O_(4) nanorods  

作　　者：Wenliang Feng Venkata Sai Avvaru Steven JHinder Vinodkumar Etacheri 

机构地区：[1]IMDEA Materials Institute,C/Eric Kandel 2,Getafe,Madrid 28906,Spain [2]Universidad Politécnica de Madrid,E.T.S.de Ingenieros de Caminos,28040 Madrid,Spain [3]Universidad Autónoma de Madrid,C/Francisco Tomás y Valiente,7,28049 Madrid,Spain [4]Surface Analysis Laboratory,Faculty of Engineering and Physical Sciences University of Surrey Guildford,Surrey GU27XH,United Kingdom

出　　处：《Journal of Energy Chemistry》2022年第6期338-346,I0009,共10页能源化学（英文版）

基　　金：financially supported by the IMDEA Materials Institute STRUBAT Project, Spanish Ministry of Economy, Industry, and Competitiveness (MINECO), the Spanish Ministry of Science and Innovation, and Comunidad de Madrid for Juan de la Cierva fellowship (IJCI-2015-25488);the Retos Investigacion Project (MAT2017-84002-C2-2-R)/Ramon y Cajal fellowship (RYC-2018-025893-I);the Talent attraction fellowship (2016-T1/IND-1300);the China Scholarship Council (201706740087)。

摘　　要：Sodium-ion hybrid capacitors (SICs) have been proposed to bridge performance gaps between batteries and supercapacitors,and thus realize both high energy density and power density in a single configuration.Nevertheless,applications of SICs are severely restricted by their insufficient energy densities (<100Wh/kg) resulted from the kinetics imbalance between cathodes and anodes.Herein,we report a nanograin-boundary-rich hierarchical Co_(3)O_(4) nanorod anode composed of~20 nm nanocrystallites.Extreme pseudocapacitance (up to 72%@1.0 mV/s) is achieved through nanograin-boundary-induced pseudocapacitive-type Na^(+) storage process.Co_(3)O_(4) nanorod anode delivers in this case highly reversible capacity (810 mAh/g@0.025 A/g),excellent rate capability (335 mAh/g@5.0 A/g),and improved cycle stability (100 cycles@1.0 A/g with negligible capacity degradation).The outstanding performance can be credited to the hierarchical morphology of Co_(3)O_(4) nanorods and the well-designed nanograinboundaries between nanocrystallites that avoid particle agglomeration,induce pseudocapacitive-type Na^(+) storage,and accommodate volume variation during sodiation-desodiation processes.Nitrogendoping of the Co_(3)O_(4) nanorods not only generates defects for extra surficial Na^(+) storage but also increases the electronic conductivity for efficient charge separation and lowers energy barrier for Na^(+) intercalation.Synergy of conventional reaction mechanism and pseudocapacitive-type Na^(+) storage enables high specific capacity,rapid Na^(+) diffusion,and improved structural stability of the Co_(3)O_(4) nanorod electrode.The SIC integrating this highly pseudocapacitive anode and activated carbon cathode delivers exceptional energy density (175 Wh/kg@40 W/kg),power density (6632 W/kg@37 Wh/kg),cycle life (6000 cycles@1.0 A/g with a capacity retention of 81%),and coulombic efficiency (~100%).

关 键 词：Sodium-ion hybrid capacitor Cobalt oxide nanorod Nanograin-boundary PSEUDOCAPACITANCE 

分 类 号：TQ138.12[化学工程—无机化工] TB383.1[一般工业技术—材料科学与工程] TM53[电气工程—电器]