How do high-voltage cathode and PEO electrolyte get along well?EIS analysis mechanism&potentiometric control strategy  

作　　者：Xiaodong Bai Chaoliang Zheng Heng Zhang Jian Liu Panpan Wang Baojia Xia Jianling Li 

机构地区：[1]State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing,Beijing 100083,China [2]Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences,Shanghai 201800,China

出　　处：《Journal of Energy Chemistry》2024年第9期424-436,共13页能源化学（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (Nos. 51972023, 11210304)

摘　　要：PEO-based all-solid-state electrolytes are extensively utilized and researched owing to their exceptional safety,low-mass-density,and cost-effectiveness.However,the low oxidation potential of PEO makes the interface problem with the high-voltage cathode extremely severe.In this work,the impedance of PEO-based all-solid-state batteries with high-voltage cathode(NCM811)was studied at different potentials.The Nyquist plots displayed a gyrate arc at low-frequencies for NCM811/PEO interface.Based on the kinetic modeling,it was deduced that there is a decomposition reaction of PEO-matrix in addition to de-embedded reaction of NCM811,and the PEO intermediate product(dehydra-PEO)adsorbed on the electrode surface leading to low-frequency inductive arcs.Furthermore,the distribution of relaxation time shows the dehydra-PEO results in the kinetic tardiness of the charge transfer process in the temporal dimension.Hence,an artificial interface layer(CEI_(x))was modified on the surface of NCM811 to regulate the potential of cathode/electrolyte interface to prevent the high-voltage deterioration of PEO.NCM/CEI_(x)/PEO batteries exhibit capacity retentions of 96.0%,84.6%,and 76.8%after undergoing 100 cycles at cut-off voltages of 4.1,4.2,and 4.3 V,respectively.Therefore,here the failure mechanism of high-voltage PEO electrolyte is investigated by EIS and a proposed solving strategy is presented.

关 键 词：PEo-based electrolyte High-voltage cathode Electrochemical impedance spectroscopy Mechanism research Electrochemical characteristic 

分 类 号：TM91[电气工程—电力电子与电力传动] O646[理学—物理化学]