高镍/硅碳锂离子电池高温条件下的产气研究

Investigations of gas for Ni-rich/Si-C lithium ion batteries under high temperature condition

目前对高镍LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811)/硅碳(Si-C)体系的电池研究主要集中在循环容量方面,对影响电池可靠性产气的研究较少,尤其不同SOC(state of charge,荷电状态)状态下存储和循环过程中产气行为和机理的系统研究尚未报道。本文采用排水法测产气量,气相色谱-质谱联用(GC-MS)技术测气体成分,使用单极片存储的方法分析产气来源,系统研究了商用软包装锂离子电池在高温中不同SOC状态下的存储,重点分析100%SOC和0%SOC的存储,以及循环中的产气行为。研究表明:在高温中0%~100%SOC区间内,产气量曲线呈现浴盆形状的变化规律。100%SOC下产气明显,随时间持续增加,气体成分主要是CO_(2)和CO;FEC和注液系数对产气影响显著;产气主要来源于电解液中的EC和NCM811的反应,其次为FEC和NCM811、Si-C的反应。0%SOC下产气平缓,稳定后随时间无变化,主要是CO_(2),CO和H_(2);产气主要来源于电解液和Si-C的反应。在高温循环过程中,主要产生的气体包括CO_(2),CO和H_(2)。此外,循环后的电芯在高温存储时产气会加剧;在循环过程中,高温存储产生的部分气体会被吸收。

The investigations have been mainly focused on the cycling capacity of Ni-rich LiNi_(0.8)Co_(0.1)Mn_(0.1)O_2(NCM811) cathode and silicon carbon(Si-C) anode batteries,and there are few studies on the gas generation affecting the reliability of batteries,especially the overall researches on the gas generation and mechanism during different SOCs storage and cycle processes.In this work,the drainage method has been employed to measure gas volume,gas chromatography-mass spectrometry(GC-MS) technology to analyze gas component,and single electrode plate storage method to evaluate the gas source,which systematically investigates the high-temperature storage gas under different SOCs condition,especially 100%SOC and 0%SOC,and the cycle gas of commercial soft park lithium ion batteries.The results show that the gas volume curve is the shape of the bath in the range of 0~100%SOC.Gas volume is obvious at 100%SOC,continuously increasing with time,and the major reaction productions are CO_(2) and CO.FEC content and injection coefficient have a significant effect on gas generation.The gas productions are mainly caused by reactions of EC and NCM811,secondarily by FEC and NCM811,Si-C.Gas generation is gentle at 0%SOC,and no change with time after stabilization,mainly CO_2,CO,and H_2.The gas productions mainly come from the electrolyte and Si-C reaction.The major gas components are CO_2,CO,and H_(2) during high temperature cycle.In addition,the gas generation of battery followed cycle is worsened at high temperature storage;the gas produced at high temperature storage is partly absorbed during the cyclic process.