电解质
熔点
溶剂
溶剂化
化学
石墨
锂(药物)
冰点
无机化学
化学工程
物理化学
热力学
有机化学
电极
内分泌学
工程类
物理
医学
作者
Xiaohua Deng,Shu Zhang,Cheng Chen,Qianhao Lan,Guozhu Yang,Tingting Feng,Haiping Zhou,Hongyan Wang,Ziqiang Xu,Mengqiang Wu
标识
DOI:10.1016/j.electacta.2022.140268
摘要
To achieve desirable performance of lithium-ion batteries at low temperatures, using co-solvents with low melting points, especially carboxylic esters, is an efficient strategy and thus, there is a general question: does the co-solvent with a lower melting point correspond to the composite electrolytes with better performance? Herein, we chose two constitutional isomers with 22 °C of difference in melting point, ethyl propionate and propyl acetate, as the co-solvent in the formula of two low-temperature electrolytes for comparison. At low temperatures, the Li||LiNi0.8Co0.1Mn0.1O2 coin cells and graphite||LiNi0.8Co0.1Mn0.1O2 pouch cells using the two electrolytes show close capacity retention, suggesting that the co-solvent with a lower melting point does not necessarily result in better low-temperature performance. Molecular dynamics simulations indicate that the similar solvation structure of contact ion pair for the two electrolytes is mainly responsible for their similar low-temperature performance. Furthermore, the Li||LiNi0.8Co0.1Mn0.1O2 and graphite||LiNi0.8Co0.1Mn0.1O2 cells with the two electrolytes at ambient temperature show capacity retention of 84.1%, 84.3% after 200 cycles and 88.2%, 89.6% after 360 cycles, respectively, demonstrating the reliability of the electrolytes. The results of this study provide general guidance for the development of low-temperature electrolyte regarding the choice of co-solvents.
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