高比能锂离子电池电解液配方分析改善

Improved formulation analysis of electrolytes for high specific energy lithium ion batteries

针对300 Wh/kg高比能锂离子动力电池在不同循环寿命状态下的电解液进行残余成分分析,其中正极材料为三元高镍材料NCM811,负极材料为石墨和氧化亚硅混合材料。研究结果表明:电解液添加剂VC及DTD主要作用于化成阶段及循环前期的SEI膜形成;FEC在化成阶段几乎不消耗,主要作用在循环后期,修补由于硅负极膨胀导致的SEI膜破裂;PS则在常温循环中消耗较少。此研究明确揭示了各添加剂的作用阶段及消耗量,同时以电池中残液组成成分随不同循环寿命的变化规律作为电解液配方技术精准调控方法。

To improve the electrolyte composition,the residual composition of the electrolyte used in 300 Wh/kg high energy density lithium ion battery was analyzed under different cycle life conditions.The positive electrode material was NCM811,and the negative electrode material was the mixture of graphite and silicon oxide.The results showed that the electrolyte additives VC and DTD mainly affected battery formation and the formation of SEI film in the early cycle stage.FEC was consumed in the late cycle to restore the SEI film which was destroyed by the expansion of the silicon anode.PS was less consumed during the cycle at room temperature.This study reveals the action stage and consumption of each additive in the cycle,the variation rule of residual liquid composition and cycle life under different conditions was used as the precise control method of electrolyte formulation technology.