Critical role of corrosion inhibitors modified by silyl ether functional groups on electrochemical performances of lithium manganese oxides

作     者：Min Ji Seong Taeeun Yim Min Ji Seong;Taeeun Yim

作者机构：Department of ChemistryIncheon National UniversityYeonsu-gu 22012IncheonRepublic of Korea Research Institute of Basic SciencesCollege of Natural ScienceIncheon National UniversityYeonsu-gu 22012IncheonRepublic of Korea 

出 版 物：《Journal of Energy Chemistry》 (能源化学（英文版）)

年 卷 期：2020年第29卷第12期

页      面：425-433页

核心收录：

学科分类：0808[工学-电气工程] 08[工学] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：supported by National Research Foundation of Korea grant from the Korean government (MSIP) (NRF2019R1C1C1002249  and NRF-2017M1A2A2044506) 

主　　题：Lithium-ion batteries Lithium manganese oxide cathode Electrolyte additive Corrosion Silyl ether Fluoride scavenger 

摘      要：Lithium manganese oxides(Li Mn2 O4, LMO) have attracted significant attention as important cathode materials for lithium-ion batteries(LIBs), which require fast charging based on their intrinsic electrochemical properties. However, these properties are limited by the rapid fading of cycling retention, particularly at high temperatures, because of the severe Mn corrosion triggered by the chemical reaction with fluoride(F-) species existing in the cell. To alleviate this issue, three types of silyl ether(Si–O)-functionalized task-specific additives are proposed, namely methoxytrimethylsilane, dimethoxydimethylsilane, and trimethoxymethylsilane. Ex-situ NMR analyses demonstrated that the Si-additives selectively scavenged the F-species as Si forms new chemical bonds with F via a nucleophilic substitution reaction due to the high binding affinity of Si with F-, thereby leading to a decrease in the F concentration in the cell. Furthermore, the addition of Si-additives in the electrolyte did not significantly affect the ionic conductivity or electrochemical stability of the electrolyte, indicating that these additives are compatible with conventional electrolytes. In addition, the cells cycled with Si-additives exhibited improved cycling retention at room temperature and 45 °C. Among these candidates, a combination of MTSi and the LMO cathode was found to be the most suitable choice in terms of cycling retention(71.0%), whereas the cell cycled with the standard electrolyte suffered from the fading of cycling retention triggered by Mn dissolution(64.4%). Additional ex-situ analyses of the cycled electrodes using SEM, TEM, EIS, XPS, and ICP-MS demonstrated that the use of Si-additives not only improved the surface stability of the LMO cathode but also that of the graphite anode, as the Si-additives prevent Mn corrosion. This inhibits the formation of cracks on the surface of the LMO cathode, facilitating the formation of a stable solid electrolyte interphase layer on the su