Affiliation:
1. National-Provincial Laboratory of Special Function Thin Film Materials School of Materials Science and Engineering Xiangtan University Hunan 411105 China
2. School of Information and Electronic Engineering Hunan University of Science and Technology Hunan 411201 China
3. Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials School of Materials Science and Engineering South China University of Technology Guangzhou 510641 China
Abstract
AbstractLithium fluoride (LiF) at the solid electrolyte interface (SEI) contributes to the stable operation of polymer‐based solid‐state lithium metal batteries. Currently, most of the methods for constructing lithium fluoride SEI are based on the design of polar groups of fillers. However, the mechanism behind how steric hindrance of fillers impacts LiF formation remains unclear. This study synthesizes three kinds of porous polyacetal amides (PAN‐X, X=NH2, NH‐CH3, N‐(CH3)2) with varying steric hindrances by regulating the number of methyl substitutions of nitrogen atoms on the reaction monomer, which are incorporated into polymer composite solid electrolytes, to investigate the regulation mechanism of steric hindrance on the content of lithium fluoride in SEI. The results show that bis(trifluoromethanesulfonyl)imide (TFSI−) will compete for the charge without steric effect, while excessive steric hindrance hinders the interaction between TFSI− and polar groups, reducing charge acquisition. Only when one hydrogen atom on the amino group is replaced by a methyl group, steric hindrance from the methyl group prevents TFSI− from capturing charge in that direction, thereby facilitating the transfer of charge from the polar group to a separate TFSI− and promoting maximum LiF formation. This work provides a novel perspective on constructing LiF‐rich SEI.
Funder
National Natural Science Foundation of China