Insight into the structural evolution and thermal behavior of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode under deep charge  

作　　者：Chen Liang Lihua Jiang Zesen Wei Wenhua Zhang Qingsong Wang Jinhua Sun 

机构地区：[1]State Key Laboratory of Fire Science,University of Science and Technology of Chin1,Hefei 230026,Anhui,China [2]National Synchrotron Radiation Laboratory,University of Science and Technology of Chin1,Hefei 230026,Anhui,China

出　　处：《Journal of Energy Chemistry》2022年第2期424-432,共9页能源化学（英文版）

基　　金：supported by the National Natural Science Foundation of China(No.51976209);the Fundamental Research Funds for the Central Universities(No.WK2320000040);the Synchrotron Radiation Joint Fund of University of Science and Technology of China;supported by Youth Innovation Promotion Association CAS(No.Y201768)。

摘　　要：By virtue of the crucial effect of the crystal structure and transition metal(TM)redox evolution on the performance of LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM)cathode,systematical investigation is carried out to better understand the charge mechanism upon deep charging.Based on the results of X-ray diffraction and highresolution transmission electron microscope,phase transformations existing on particle surface are promoted by high potential because of the deeper lithium vacancies,accompanied by more substantial structure instability.Soft X-ray absorption spectroscopy indicates that Ni acts as the major contributor to charge compensation while Co displays a remarkable redox activity over the deep charge range.The elevated integrated intensity of pre-edge in O K-edge spectra reveals the extensive amount of holes formed in O 2 p orbitals and the enhanced hybridization of TM 3 d-O 2 p orbitals.Considering the close relationship between thermal behavior and structural evolution,the tendency of phase transitions and O_(2) release upon heating is accelerated by voltage rise,demonstrating the aggravated instability due to deeper Li utilization.Remaining Li contents in NCM are employed to estimate the amount of oxygen released in structural transformation and its detrimental effect on stability declares Li contentdependent characteristics.Furthermore,the extended Li vacancies,higher proportion of Ni4+and stronger orbital hybridization are considered as three factors impeding the thermal stability of the highlydelithiated NCM.

关 键 词：Lithium ion battery safety OVERCHARGE Soft X-ray absorption spectroscopy Thermal property Cathode material 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ131.11[化学工程—无机化工]