软包装锂离子电池腐蚀预测和控制

Prediction and control of corrosion in pouch Li-ion battery

以20 Ah磷酸铁锂软包装锂离子电池为研究对象,对比边电压(正极极耳与铝塑膜之间电压)和边电阻(负极极耳与铝塑膜之间电阻)筛选判定铝塑膜腐蚀情况的可靠性、可行性。通过电化学镀铜法测试聚丙烯(PP)层破损面积,可判定离子短路,发现边电阻比边电压更准确。通过负极耳与铝塑膜之间并联不同阻值电阻模拟电子短路,发现在判定电子短路时,边电压比边电阻更加准确。统计电池生产过程数据,发现离子短路无法彻底避免,因此控制电子短路是防止软包装电池腐蚀的较优选择。采用三电极方式测试铝箔的腐蚀电流,预测不同边电压下铝塑膜的腐蚀寿命。控制边电压值小于2.413 V,可保证软包装电池在使用周期内不发生腐蚀漏液。

20 Ah lithium iron phosphate pouch Li-ion battery is taken as the research object,the reliability and feasibility of determination based on side voltage(voltage between cathode tab and aluminum laminated film)and side resistance(resistance between anode tab and aluminum laminated film)for the corrosion of aluminum laminated film are compared.Ion short-circuit can be determined by measuring the damage area of the polypropylene(PP)layer by electrochemical copper plating method.It is found that the side resistance is more accurate than the side voltage to determine ion short-circuit.The electronic short-circuit is simulated by paralleling different electric resistances between the anode tab and the aluminum laminated film.It is found that the side voltage is more accurate than the side resistance to determine electronic short-circuit.According to the statistics of battery production process data,the ion short-circuit cannot be completely avoided,so controlling electronic short-circuit is a better choice to prevent the corrosion of pouch batteries.The corrosion current of aluminum foil is tested by the three-electrode method,and the corrosion life of aluminum laminated film under different side voltages is calculated and predicted.Controlling the side voltage value lower than 2.413 V can ensure that the pouch battery does not undergo corrosion leakage during the service life.