磷酸铁锂动力电池工况循环性能研究

重点研究了不同温度、不同功率等级的工况循环条件下,磷酸铁锂动力电池容量、内阻等的变化规律,期望对建立合理的循环寿命评价测试方法有所帮助。研究结果显示:25℃、100%功率等级条件下,循环72815次,即满足相应车型行驶8.0×104km,电池容量衰减了5.6%,直流内阻增加9.6%。工况循环过程中电池正、负极嵌入–脱嵌能力均有不同程度衰减,但负极衰减更大,其SEI膜(固体电解质相界面膜)阻抗、电荷转移阻抗有显著增加。

Study on operating mode cycle performance of lithium ion power battery with natural graphite and LiFePO4

The variation rules of capacities and internal resistances of lithium ion power battery with LiFePO_4 electrode were studied at different temperatures and simulated levels of the operating mode cycle to develop reasonable cycle life evaluation and testing methods. The results show that after 72 815 cycles, equivalent to corresponding vehicle driving for 8.0×10~4 km, capacity fade and the increase of DC internal resistance are 5.6% and 9.6% respectively at 25 ℃ and 100% simulated level. During the operating mode cycling, the capability fade of lithiation-delithiation is mainly attributed to the cathode of battery, although the anode also has a certain extent fade. The increasing of impedance of SEI film (solid dielectric phase interfacial film) and charge transfer resistance is obvious.