Abstract:A prismatic 204056-type high　power lithium-ion battery was developed. Modified LiMn₂O₄ and carbonaceous mesophase sphere (CMS) were adopted as the cathode and anode, respectively. The effects of proportion of conductive carbon black in cathode and the rest time after discharge on the electrochemical properties of batteries were investigated. The electrochemical tests show that the proportion of conductive carbon black in cathodes affects the high rate capability and discharge voltage plateau distinctly. The battery with 3.0% of conductive carbon black in cathode shows excellent electrochemical performances when being charged/discharged within 2.5−4.2 V at room temperature. The discharge capacity at 20C rate is 94.4% of that at 1C rate, and the capacity retention ratio charged at 1C and discharged at 5C is 86.6% after 390 cycles at room temperature. The test result of impulse discharge at 50C for 5 s shows that the battery has outstanding high rate discharge performance when the battery is in the depth of charge of 90%, 75%, 60%, 45%, 30% and 15%. The battery also shows good charge performance. When the battery is charged at 0.5C, 1C, 2C and 4C, the ratios of capacity for constant current charge are 98.4%, 96.4%, 91.0% and 72.9% of the whole charge capacity, respectively. In addition, the rest time after discharge affects the cycle performance distinctly when the battery is discharged at high rate.

Key words: lithium ion batteries; LiMn₂O₄; electrochemical property; rate capability