锂离子电池充放电机械压力特性研究

软包锂离子电池在充放电期间因为锂离子的脱嵌使得电池表面产生形变进而形成机械压力。通过对软包锂离子电池施加一定预紧力后进行正常与滥用的充放电试验研究，揭示电池表面机械压力的变化特性规律。结果表明：在正常充电阶段，电池表面机械压力逐渐增大，在正常放电阶段，电池表面机械压力是一个逐渐恢复的过程；在滥用的过充电与过放电阶段，电池表面机械压力均表现出先缓慢增大后迅速增大(dF/dt>>0)的现象。针对过充电和过放电电池表面机械压力迅速增加的特点，进一步基于滥用特性提出锂离子电池热失控预警电压的确定方法和锂离子电池放电截止电压的确定方法，为软包锂离子电池的安全性设计和电池管理系统中过充电、过放电提供理论依据与方法指导。

Study on Mechanical Pressure Characteristics of Charge and Discharge of Lithium-ion Battery

During the charging and discharging of the soft-pack lithium-ion battery, the surface of the battery will deform due to the disembedding of lithium-ions, thus forming mechanical pressure. The normal and abuse charging-discharging experiments are carried out on the soft-pack lithium-ion battery after a certain preload applied, to reveal the change characteristics of the mechanical pressure on the battery surface.The results show that the surface mechanical pressure of the battery increases gradually during the normal charging stage, while the surface mechanical pressure of the battery recovers gradually during the normal discharging stage. In the over-charging and over-discharging stages of abuse, the surface mechanical pressure of the battery increases slowly at first and then rapidly (dF/dt>>0). In view of the rapid increase of mechanical pressure on the surface of over-charging and over-discharging batteries, the determination method of thermal runaway warning voltage and discharge cut-off voltage of lithium-ion batteries are further proposed based on the abuse characteristics,which will provide theoretical basis and method guidance for the safety design of soft-pack lithium-ion battery and the battery system management of overcharging and overdischarging.