三(三甲基硅烷)类添加剂助力5V镍锰酸锂电池实用化  

Tris(trimethylsilyl)-Based Additives Enables Practical 5V LiNi_(0.5)Mn_(1.5)O_(4) Batteries

作　　者：张立恒 顾海涛[2] 罗英[2] 董庆雨 沈炎宾 解晶莹 ZHANG Li-Heng;GU Hai-Tao;LUO Ying;DONG Qing-Yu;SHEN Yan-Bin;XIE Jing-Ying(School of Chemistry and Chemical Engineering,Harbin Institute of Technology,Harbin 150001,China;State Key Laboratory of Space Power-Sources Technology,Shanghai Institute of Space Power-Sources,Shanghai 200245,China;i-Lab,CAS Center for Excellence in Nanoscience,Suzhou Institute of Nano-Tech and Nano-Bionics,Chinese Academy of Sciences,Suzhou,Jiangsu 215123,China)

机构地区：[1]哈尔滨工业大学化工与化学学院,哈尔滨150001 [2]上海空间电源研究所,空间电源技术国家重点实验室,上海200245 [3]中国科学苏州纳米技术与纳米仿生研究所国际实验室卓越纳米科学中心,苏州215123

出　　处：《无机化学学报》2022年第10期2091-2102,共12页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金(No.21805186,21625304,21733012);上海启明星项目(No.20QB1401700);上海科学技术委员会项目(No.19160760700)资助。

摘　　要：基于LiNi_(0.5)Mn_(1.5)O_(4)的5 V电池尚未实现实际应用,解决这一问题的关键在于电解液调控和电极界面优化。我们系统性研究了三(三甲基硅烷)硼酸酯(TMSB)和三(三甲基硅烷)亚磷酸酯(TMSPi)作为常规碳酸乙烯酯(EC)⁃LiPF_(6)基电解液添加剂在LiNi_(0.5)Mn_(1.5)O_(4)电池体系中的应用。结合理论计算、物理化学表征以及电化学手段分析了三(三甲基硅烷)类添加剂在高压电解液中的作用机制。研究发现,TMSB和TMSPi均可以通过优化电极/电解液界面来提高LiNi_(0.5)Mn_(1.5)O_(4)循环稳定性和库仑效率。TMSB中缺电子B可与阴离子相互作用,稳定PF_(6)^(-),抑制LiNi_(0.5)Mn_(1.5)O_(4)正极阻抗的持续增加。TMSPi具有更高的最高占据分子轨道(HOMO)能级,可在更低电位下钝化高压正极,提高LiNi_(0.5)Mn_(1.5)O_(4)放电电压平台和放电容量。此外,TMSPi还可通过亲核反应参与石墨界面组分优化,改善负极循环性能。石墨||LiNi_(0.5)Mn_(1.5)O_(4)软包电池在含1%TMSPi电解液中1C循环100次后的容量保持率为88.9%,优于基础电解液(60.5%)和含1%TMSB的电解液(77.4%)。LiNi_(0.5)Mn_(1.5)O_(4) cathode materials have been considered promising candidates for high energy density Li⁃ion batteries due to their high operation potential.However,to develop 5 V LiNi_(0.5)Mn_(1.5)O_(4)⁃based batteries,practi⁃cal electrolytes with high electrochemical stability are yet to be realized.In this work,tris(trimethylsilyl)⁃based addi⁃tives,including tris(trimethylsilyl)borate(TMSB)and tris(trimethylsilyl)phosphite(TMSPi),were selected as electro⁃lyte additives for typical ethylene carbonate(EC)⁃LiPF_(6) based electrolyte to develop practical LiNi_(0.5)Mn_(1.5)O_(4)⁃based batteries.Combining theoretical calculations,physicochemical characterization,and electrochemical measurements,we found that both TMSB and TMSPi can improve the Coulombic efficiency and cycling stability of 5 V LiNi_(0.5)Mn_(1.5)O_(4)⁃based cells.Specifically,TMSB can act as the stabilizer for PF_(6)^(-) due to its electron deficiency nature,thereby suppressing the increase of cell impedance.In addition,thanks to its high highest occupied molecule orbital(HOMO)energy level,TMSPi can be preferentially oxidized on the surface of charged LiNi_(0.5)Mn_(1.5)O_(4) electrodes,resulting in a decent rate capacity and high discharge platform.In addition,TMSPi is conducive to the formation of robust solid electrolyte interphase(SEI)on graphite anode through the nucleophilic attack,resulting in enhanced cycle performance.As a result,Graphite||LiNi_(0.5)Mn_(1.5)O_(4) pouch cells with TMSPi⁃containing electrolyte displayed capacity retention of 88.9% after 100 cycles at 1C,superior to that in the blank(60.5%)and TMSB⁃containing(77.4%)electrolytes.

关 键 词：电解液添加剂 LiNi_(0.5)Mn_(1.5)O_(4) 三(三甲基硅烷)硼酸酯 三(三甲基硅烷)亚磷酸酯 

分 类 号：O646.21[理学—物理化学]