Experimental Study of Discharge Characteristics of NCM 18650 Batteries at Low-temperature Environment

To study the cryogenic properties of NCM (Ni, Co, Mn) batteries, domestic 2.6 A·h cells and a self-made 23.4 A·h battery module were tested. The purpose of this research was to study the properties of the NCM batteries such as discharge voltage, discharge capacity and temperature characteristics under different discharge rates at a low temperature. The results show that when the ambient temperature is -20℃, the discharge terminal voltage curve of cell and battery module has a nonlinear variation. The discharge capacity of cell decreases with the increase of the discharge rate. The battery module has an opposite behavior. The discharge rate is greater, the heat release of the battery is larger, and the temperature is higher. The temperature rise of the center cell in a battery module is 2.6 times as large as a cell.