Plum pudding model inspired KVPO4F@3DC as high-voltage and hyperstable cathode for potassium ion batteries  

三维碳包覆氟磷酸钒钾构筑超稳定高电压钾电正极

作　　者：Zhaomeng Liu Jue Wang Bingan Lu 刘朝孟;王珏;鲁兵安(School of Physics and Electronics,Hunan University,Changsha 410082,China;College of Chemistry and Chemical Engineering,Central South University,Changsha 410083,China;State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University,Changsha 410082,China;Fujian Strait Research Institute of Industrial Graphene Technologies,Quanzhou 362000,China)

机构地区：[1]School of Physics and Electronics,Hunan University,Changsha 410082,China [2]College of Chemistry and Chemical Engineering,Central South University,Changsha 410083,China [3]State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,Hunan University,Changsha 410082,China [4]Fujian Strait Research Institute of Industrial Graphene Technologies,Quanzhou 362000,China

出　　处：《Science Bulletin》2020年第15期1242-1251,M0003,共11页科学通报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(51672078 and 21473052);Hunan University State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Independent Research Project(71675004);Hunan Youth Talents(2016RS3025)。

摘　　要：The investigation on the cathode material of potassium ion batteries(PIBs),one of the most promising alternatives to lithium ion batteries,is of great significance.Potassium vanadium fluorophosphate(KVPO4F)with a high working voltage is an appealing cathode candidate for PIBs,while the poor cycling performance and low electronic conductivity dramatically hinder the application.Herein,a plum pudding model inspired three-dimensional amorphous carbon network modified KVPO4F composite(KVPO4F@3DC)is successfully designed in this study to tackle these problems.In the composite,KVPO4F particles are homogeneously wrapped by a layer of amorphous carbon and bridged by crosslinked large area carbon sheets.As the cathode for PIBs,the KVPO4F@3DC composite exhibits a high average operating voltage about 4.10 V with a super-high discharge capacity of 102.96 mAh g^-1 at 20 mA g^-1.An excellent long cycle stability with a capacity retention of 85.4%over 550 cycles at 500 mA g^-1 is achieved.In addition,it maintains 83.6%of its initial capacity at 50 mA g^-1 after 100 cycles at 55℃.The design of KVPO4F@3DC with plum pudding structure provides facilitative electron conductive network and stable electrode/electrode interface for electrode,successfully innovating an ultra-stable and high-performance cathode material for potassium ion batteries.开发环保、低成本的新型正极材料对钾离子电池的发展具有重要意义.高达4.0V的工作电压,使得氟磷酸钒钾(KVPO4F)成为一种极具吸引力的钾电正极材料.然而,KVPO4F材料低的电子导电性(1.84×10^-5 S m^-1)和不稳定的电极/电解质界面,导致其较差的循环稳定性.本文设计并制备由无定型热解碳层及三维导电碳网络对KVPO4F颗粒进行三维包覆,得到KVPF@3DC复合正极并展现出优异的电化学性能.在20,50和500 mA g^-1电流速率下,其放电比容量分别为102.96、96.01和60.02 mAh g^-1;在500 mA g^-1条件下循环550次后,循环保持率高达83.6%.复合材料中,热解碳层均匀包覆在KVPO4F不规则纳米颗粒表面,而三维导电网络则成功连接不同的KVPO4F颗粒,这种特殊结构充分改善了KVPF@3DC复合材料的电子传导能力,同时提高了循环过程中电极材料的界面稳定性,为超稳定高电压钾离子电池正极的开发提供了思路.

关 键 词：Plum pudding model CATHODE Potassium vanadium fluorophosphate Potassium ion batteries High working voltage 

分 类 号：TM912[电气工程—电力电子与电力传动]