Performance of high power LiFePO_4/C lithium-ion battery

The 20 Ah high power LiFePO4/C lithium ion battery was developed for electric vehicles(EV),and a series of tests about battery performance were carried out.The results show that the discharge capacity retains 92.17% of the initial after 500 cycles at 10 C,which can meet the discharging demand of battery at high rate.The FreedomCAR hybrid pulse power characterization(HPPC) test indicates that the area specific impedance(ASI) of the cell is less than 30 W·cm2 at 10 s discharge pulse at 10%～70% depth of discharge(DOD).The discharge and charge pulse power capability of the cell are 1 993.9 W/kg and 1 620.9 W/kg at 50% DOD,which can meet the challenge of EV.The discharge capacity at-20 ℃ and 60 ℃ retains 61.8% and 108% of that at room temperature,respectively,which means the battery has good performance at high temperature;however,the specific energy and power at low temperature are still expected to be improved.The battery neither explodes nor catches fire with good safety characteristic under the tests of overcharge,short-circuit and nail penetration.