Research on the Early Warning Method of Thermal Runaway of Lithium Battery Based on Strain Detection of Explosion-Proof Valve

Overcharging and runaway of lithium batteries is a highly challenging safety issue in lithium battery energy storage systems. Choosing appropriate early warning signals and appropriate warning schemes is an important direction to solve this problem. This research proposes a battery overcharge warning scheme based on the hard case lithium battery explosion proof valve Strain gauge. Starting from the external strain mechanism of the lithium battery, the strain change of the lithium battery explosion proof valve under normal conditions and overcharge is studied. Based on the comparison of the two conditions, an online warning scheme using sliding window and data standard deviation is proposed. The experimental results show that: (1) under normal charging and discharging conditions, the strain of the safety valve of the lithium battery will monotonically increase with the increase of SOC and battery temperature; (2) Under overcharging conditions, the inflection point of the strain change of the explosion-proof valve occurs earlier than the characteristic gas, at most about 600 s earlier; (3) The online warning method using sliding windows and data standard deviation can advance the warning of characteristic gases by about 500 s and improve the generalization ability of the method. This study proposes a cheap and reliable early warning scheme for lithium battery energy storage systems, greatly improving the safety of battery systems.