过充条件下磷酸铁锂电池力学特性分析与安全阀优化设计

Mechanical characteristics analysis and safety valve optimization design of lithium iron phosphate battery under overcharge

磷酸铁锂电池因具有宽工作温度范围、长循环寿命而被广泛应用于电动汽车和电网储能领域,然而过充等滥用工况下的电池安全问题仍是遏制其发展的主要因素。过充等滥用会引发电池严重变形,且会挤压相邻电池。基于锂离子电池过充产热产气特性,建立了热-气-固耦合模型实现铝壳电池的压力膨胀。结果表明,当内部压力为400~800 kPa时,3003-H14铝壳最大壳体位移为5.7~10.0 mm。此外,模拟了不同材质和不同压印形状安全阀的断裂失效。仿真结果表明,具有圆形压印的Al1050-O铝合金安全阀初始断裂压力比MFX2铝合金小193.76 kPa;十字形压印安全阀的断裂压力比圆形压印小,且断裂位置在压印中心;半圆形压印安全阀的断裂压力最小,断裂位置在顶部圆弧附近。采用十字形压印或半圆形压印的安全阀能够使铝壳电池在较小的内部压力下释放气体。模型和仿真结果可为提高电池安全性提供数值支撑。

Lithium iron phosphate battery is widely used in the field of electric vehicles and power grid energy storage due to its wide operating temperature range and long cycle life.However,the battery safety problem under abuse conditions is still the main factor to curb its development.Abuse such as overcharge will cause serious deformation of the battery and squeeze adjacent batteries.Based on the characteristics of overcharge heat and gas production of lithiumion battery,a thermal,gas and solid coupling model was established to realize the pressure swelling of aluminum shell battery.The results show that when the internal pressure is 400-800 kPa,the maximum displacement of 3003-H14 aluminum shell is 5.7-10.0 mm.Then,the fracture failure of safety valves with different materials and different embossing shapes was simulated.The simulation results show that the initial fracture pressure of Al1050-O aluminum alloy safety valve with circular impression is 193.76 kPa lower than that of MFX2 aluminum alloy;the fracture pressure of the cross embossing safety valve is smaller than that of the circular embossing,and the fracture position is in the center of the embossing;the fracture pressure of the semicircular embossing safety valve is the smallest and the fracture position is near the top arc.The safety valve with cross impression or semicircular impression can release gas from aluminum shell battery under small internal pressure.The model and simulation results can provide numerical support for improving battery safety.