混合固液锂离子电池的热失控行为研究

Study on thermal runaway of hybrid solid-liquid batteries

混合固液电解质锂离子电池是一种具有高能量密度、高安全性的储能器件,有望短期内实现产业化。本工作选择混合固液电解质(LATP和电解液)匹配高比容量活性材料(正极NCM811和负极C@SiO)为研究体系,采用绝热加速量热仪和气相色谱仪对全SOC及不同全寿命周期下混合固液电解质锂离子电池进行热失控模拟和产气组分分析,并通过超声检测仪分析不同寿命周期下电解液含量的变化情况。研究结果显示:该体系新鲜电池随荷电态的增加而热安全性降低,产气量增大,且可燃气体的占比会增加。随着循环容量的衰减,电池样品的热失控起始温度、最高产热速率以及产气量变化有所差异,在容量保持率为70%时热稳定性有所改善,结合超声分析结果推测与电解液转化成固态电解质有关。该工作初步探究了该体系电池的热失控行为,为后期内部机理解析和电池设计提供了支撑。

Hybrid solid-liquid electrolyte Li-ion batteries are energy storage devices with high energy density and high safety,which can realize industrialization in a short time.In this study,a hybrid solid-liquid electrolyte(LATP and electrolyte)battery with a high specific capacity active material(positive electrode NCM811 and negative electrode C@SiO)was investigated.An accelerating rate calorimeter and gas chromatograph were used to simulate thermal runaway and analyze gas production components of battery samples under full SOCs during the cycle life.Changes in the electrolyte content were detected using ultrasonic technology.The results show that the thermal safety of fresh batteries decreases as the charge state increases,and the proportion of combustible gas increases as the gas production increases.As the capacity decreases,thermal runaway parameters,such as the thermal runaway starting temperature,maximum heat yield rate,and gas production,decrease.The safety performance is enhanced when the capacity retention rate is 70%,which is speculated to be related to the conversion of the electrolyte into a solid electrolyte.This study preliminarily investigates the thermal runaway phenomenon of the battery in this system and provides support for the internal mechanism analysis and battery design.