Effects of Temperature on the Formation of Graphite∕LiCoO[sub 2] Batteries

The effects of temperature on the formation of graphite/ batteries were studied using various electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), cyclic voltammetry, and battery performance testing. Results showed that the coulombic efficiency of the first charge and discharge for batteries at was higher than that at . The batteries with different formation temperatures of 25 and exhibited very similar cycling performance at . The EIS of batteries at was composed of two overlapped semicircles at high to medium frequency and a slope line at low frequency, while the EIS of batteries at was composed of an inductive loop at very high frequency followed by two overlapped semicircles at high to medium frequency and a slope line at low frequency. The bulk resistance of batteries at was much larger than that at . The resistance of solid electrolyte interface and charge-transfer resistance of batteries at , which were subjected to 50 cycles at , were increased greatly, and the cycle performance of batteries became obviously worse with the increase in formation temperature.