Exploration of cobalt selenite-carbon composite porous nanofibers as anode for sodium-ion batteries and unveiling their conversion reaction mechanism  

作　　者：Jin-Sung Park Gi Dae Park Yun Chan Kang 

机构地区：[1]Department of Materials Science and Engineering,Korea University,Anam-Dong,Seongbuk-Gu,Seoul,136-713,Republic of Korea

出　　处：《Journal of Materials Science & Technology》2021年第30期24-35,共12页材料科学技术（英文版）

基　　金：financially supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.NRF2019R1A2C2088047)。

摘　　要：Efforts have been made to develop a promising anode material with a novel composition for sodiumion batteries(SIBs).In this study,the sodium-ion storage mechanism of transition metal selenite that comprises transition metal cation coupled with two anions is studied.Amorphous cobalt selenite(CoSeO_(3))-carbon composite nanofibers containing numerous pores are synthesized via electrospinning process.Upon heat treatment of the electrospun nanofibers containing selenium,CoSe_(2)nanoclusters are formed.During the subsequent oxidation,CoSe_(2)transformed into amorphous CoSeO_(3)and some part of carbon was oxidized into CO_(2),leaving the pores inside the nanofiber.To unveil the electrochemical reaction mechanism,analytical methods including cyclic voltammetry,ex-situ X-ray photoelectron spectroscopy,ex-situ transmission electron microscopy,and in-situ electrochemical impedance spectroscopy techniques were adopted.Based on the analyses,the following conversion reaction from the second cycle onward is suggested:CoO+xSeO_(2)+(1-x)Se+4(x+1)Na^(+)+4(x+1)e~-?Co+(2x+1)Na_(2)O+Na_(2)Se.Furthermore,the electrochemical properties of porous CoSeO_(3)-carbon composite nanofibers are analyzed in detail.The anode material exhibited stable cycle stability up to 200 cycles at 0.5 A g^(-1)and high rate performance up to 5 A g^(-1).

关 键 词：Anode materials Sodium-ion batteries Conversion reaction Metal selenite Electrospinning 

分 类 号：TQ340.64[化学工程—化纤工业] TB383.1[一般工业技术—材料科学与工程] TM912[电气工程—电力电子与电力传动]