Li Menglu, An Hanwen, Song Yajie, Liu Qingsong, Wang Jian, Huo Hua, Lou Shuaifeng, Wang Jiajun
MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin 150001, China.
State Key Laboratory of Space Power-Sources, Harbin Institute of Technology, Harbin 150001, China.
J Am Chem Soc. 2023 Nov 29;145(47):25632-25642. doi: 10.1021/jacs.3c07482. Epub 2023 Nov 9.
Owing to high ionic conductivity and mechanical strength, poly(vinylidene fluoride) (PVDF) electrolytes have attracted increasing attention for solid-state lithium batteries, but highly reactive residual solvents severely plague cycling stability. Herein, we report a free-solvent-capturing strategy triggered by reinforced ion-dipole interactions between Li and residual solvent molecules. Lithium difluoro(oxalato)borate (LiDFOB) salt additive with electron-withdrawing capability serves as a redistributor of the Li electropositive state, which offers more binding sites for residual solvents. Benefiting from the modified coordination environment, the kinetically stable anion-derived interphases are preferentially formed, effectively mitigating the interfacial side reactions between the electrodes and electrolytes. As a result, the assembled solid-state battery shows a lifetime of over 2000 cycles with an average Coulombic efficiency of 99.9% and capacity retention of 80%. Our discovery sheds fresh light on the targeted regulation of the reactive residual solvent to extend the cycle life of solid-state batteries.
由于具有高离子电导率和机械强度，聚偏氟乙烯（PVDF）电解质在固态锂电池中受到越来越多的关注，但高活性的残留溶剂严重困扰着循环稳定性。在此，我们报道了一种由锂与残留溶剂分子之间增强的离子 - 偶极相互作用引发的无溶剂捕获策略。具有吸电子能力的二氟草酸硼酸锂（LiDFOB）盐添加剂作为锂正电态的再分配剂，为残留溶剂提供了更多的结合位点。受益于改性的配位环境，动力学稳定的阴离子衍生界面相优先形成，有效减轻了电极与电解质之间的界面副反应。结果，组装的固态电池显示出超过2000次循环的寿命，平均库仑效率为99.9%，容量保持率为80%。我们的发现为有针对性地调控活性残留溶剂以延长固态电池的循环寿命提供了新的思路。
