Abstract: Owing to the outstanding electrochemical performance, the LiFePO4 power batteries could be used on electric vehicles and hybrid electric vehicles. A kind of LiFePO4 power batteries, Cylindrical 26650, was manufactured from commercialized LiFePO4, graphite and electrolyte. To get batteries with good high-current performance, the optimal content of conductive agent was studied and determined at 8% of mass fraction. The electrochemical properties of the batteries were investigated. The batteries had high discharging voltage platform and capacity even at high discharge current. When discharged at 30 C current, they could give out 91.1% of rated capacity. Moreover, they could be fast charged to 80% of rated capacity in ten minutes. The capacity retention rate after 2 000 cycles at 1 C current was 79.9%. Discharge tests at -20 ℃ and 45 ℃ also showed impressive performance. The battery voltage, resistance and capacity varied little after vibration test. Through the safety tests of nail, no inflammation or explosion occurred.

Key words: hybrid and electric vehicles, power batteries, lithium iron phosphate, lithium ion batteries