Atomic-scale structural and chemical evolution of Li3V2(PO4)3 cathode cycled at high voltage window  

作　　者：Shulin Chen Jian Zou Yuehui Li Ning Li Mei Wu Jinghuang Lin Jingmin Zhang Jian Cao Jicai Feng Xiaobin Niu Jianming Bai Junlei Qi Peng Gao Liping Wang Hong Li 

机构地区：[1]School of Materials and Energy,State Key Laboratory of Electronic Thin Film and Integrated Devices,University of Electronic Science and Technology oj China,Chengdu 610054,China [2]State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin 150001,China [3]Electron Microscopy Laboratory,School of Physics,Peking University,Beijing 100871,China [4]National Synchrotron Light Source II,Brookhaven National Laboratory,Upton,New York 11973,USA [5]Collaborative Innovation Center of Quantum Matter,Beijing 100871,China [6]International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China [7]Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China

出　　处：《Nano Research》2019年第7期1675-1681,共7页纳米研究（英文版）

基　　金：supported by the National Natural Science Foundation of China (Nos.51502032,51575135,U1537206,51502007,and 51672007);the National Basic Research Program of China (Nos.2016YFA0300804 and 2016YFA0300903];"2011 Program" Peking-Tsinghua-IOP Collaborative Innovation Center of Quantum Matter.

摘　　要：Here,by using atomically resolved scanning transmission electron microscopy and electron energy loss spectroscopy,we investigate the structural and chemical evolution of Li3V2(PO4)3 (LVP) upon the high-voltage window (3.0-4.8 V).We find that the valence of vanadium gradually increases towards the core corresponding to the formation of electrochemically inactive Li3-xV2(PO4)3 (L3-xVP) phases.These Li-deficient phases exhibit structure distortion with superstructure stripes,likely caused by the migration of the vanadium,which can slow down the lithium ion diffusion or even block the diffusion channels.Such kinetic limitations lead to the formation of Li-deficient phase along with capacity loss.Thus,the LVP continuously losses of electrochemical activity and Li-deficient phases gradually grow from the particle core towards the surface during cycling.After 500 cycles,the thickness of active LVP layer decreases to be - 5-20 nm.Moreover,the micromorphology and chemical composition of solid electrolyte interphase (SEI) have been investigated,indicating the thick SEI film also contributes to the capacity loss.The present work reveals the structural and chemical evolution in the cycled electrode materials at an atomic scale,which is essential to understand the voltage fading and capacity decaying of LVP cathode.

关 键 词：LITHIUM-ION batteries Li-deficient lithium vanadium phosphate capacity fading solid electrolyte INTERPHASE scanning transmission ELECTRON microscopy ELECTRON energy loss spectroscopy 

分 类 号：O4[理学—物理]