Enhancing overcharge cycling endurance of lithium-ion batteries via a multifunctional electrolyte

Lithium-ion battery plays a crucial role in large-scale energy storage systems, while its safety is vulnerable to overvoltage abuse. Although battery management systems (BMS) are commonly integrated to address this issue, there remains a potential risk of overcharge due to the large number and inherent inconsistencies of batteries in the systems. In this study, a multifunctional electrolyte is proposed to enhance the overcharge endurance of lithium-ion battery. The introduced difluoroethylene carbonate (DFEC), ethoxy(pentafluoro)cyclotriphosphazene (PFPN), and hexanetricarbonitrile (HTCN) additives provide high anodic stability, desirable compatibility with lithium (Li) plating, and strong ability to suppress iron (Fe) dissolution. The underlying mechanisms are thoroughly investigated with in situ electrochemical analysis, morphological observation and interphase characterization. Benefiting from the multifunctional electrolyte, 2 Ah LFP|Gr pouch cell exhibits superior capacity retention rate of 99.2 % after 500 cycles with a 4.5 V overcharge protocol. This work presents a feasible strategy to mitigate safety risks in lithium-ion batteries subjected to overcharge abuse and offers guidance for safe electrolyte design.