Abstract: In this paper,a lithium-ion battery with lithium titanite oxide（LTO）as the anode material is investigated. This paper investigates the electrical performance and temperature rise of batteries at different multipliers and tests them at 66C（C is the maximum capacity）in continuous cycles. The experiments concluded that the battery reached its maximum temperature rise at 66C,with a maximum temperature of 51.72 ℃ and a maximum temperature difference of 25.65 ℃,of which the maximum heat production rate was 739.97 W. The discharge depth of the battery at 66C discharge rate is only 42% of the total charge. As the number of cycles and discharge rate increase, the internal resistance of the battery shows a gradually decreasing trend, reaching a minimum of 0.63 mΩ.Finally,the Kalman filter algorithm was improved by applying the extended Kalman filter algorithm to predict the capacity decay of the battery based on the cyclic discharge of the battery at a high rate,and the applicability of this algorithm was verified under the high rate of discharge. The maximum error is within 0.05,which is a good result.