低温型锂离子电池中的非水电解质研究进展

Nonaqueous electrolyte in low-temperature lithium-ion battery

锂离子电池已在移动设备、电动交通工具和储能系统等领域得到广泛应用。开发能够在低温条件下稳定工作的锂离子电池,可满足科学探索与军事战略地位的高寒地区、两极地区,以及高空和近太空等区域对能量储存及释放的需求。电解液作为锂离子电池中一个重要组成部分,对低温下锂离子电池的性能表现起着决定性的作用。传统碳酸酯电解液的高熔点以及低温下的离子传输速度缓慢的特性,会导致寒冷环境下电池输出功率的下降甚至电池失效。引入低熔点组分溶剂,降低碳酸乙烯酯溶剂在电解液中的比例或者设计无碳酸乙烯酯电解液,可以有效改善电解液的液程范围和离子导电能力,从而减小电池极化,提升锂离子电池的低温性能。本文首先从电解液的角度阐述了LIBs在低温下的失效原因和析锂机制。在此基础上,探讨了近五年来关于低温电解液设计的研究成果和改性策略,包括溶剂分子、锂盐和成膜添加剂的选择等。此外,介绍了近年来提出的高熵电解液、稀释高浓电解液和弱溶剂化电解液等新型电解液设计策略。最后,总结了低温电解液设计策略的优缺点、科学挑战,并就该领域的现状提出了未来可能的发展方向。

Lithium-ion batteries(LIBs)are extensively used in various sectors including mobile devices,electric transportation,and energy storage systems.Their ability to reliably perform in cold environments—such as alpine regions,polar areas,and high-altitude or near-space environments critical to scientific exploration and military strategy—is of paramount importance.Electrolytes have a great influence on the low-temperature performance aspects of lithium-ion batteries.The high melting points and sluggish ion transfer of conventional carbonate electrolytes in cold conditions pose substantial challenges,often leading to reduced power output or even battery failure.Strategies such as introducing solvents with lower melting points,reducing the proportion of ethylene carbonate,or designing ethylene carbonate-free electrolytes have proven effective.These measures broaden the electrolyte's liquid range and enhance ionic conductivity,which in turn mitigates battery polarization and improves LIB performance at low temperatures.This paper first analyzes the failure mechanisms and lithium precipitation behavior of LIBs at low temperatures from the perspective of the electrolyte.Subsequently,it discusses research findings and modification strategies for low-temperature electrolytes over the past 5 years,including the selection of solvent molecules,lithium salts,and film-forming additives.This paper also introduces recent innovations in electrolyte design,such as high-entropy electrolytes,diluted high-concentration electrolytes,and weakly solvated electrolytes.Finally,it presents a comprehensive examination of the advantages,drawbacks,and scientific challenges associated with designing low-temperature electrolytes,culminating in proposed future research directions based on the current state of the field.