Experimental Studies on Battery Low-Temperature Behaviors and Two Heating Approaches

The discharge and long-term cycle behaviors of a 18650 type Li-ion batteries under different operating environments are studied through experimental tests. As temperature drops to and below -10°C, the accessible capacity of the battery is significantly decreased, which is mainly attributed to the high overpotential arising from the dramatically elevated battery internal resistance that cuts off the discharge. After comparing the cycle test results of the 18650 type batteries tested in ambient condition and at -10°C, a dramatic capacity fading was found in the battery cycled at a low temperature, which is attributed to the irreversible lithium metal formation on the anode. Furthermore, two heating approaches, forced convective heating and alternating current (AC) heating, were tested on the battery. Significant temperature non-uniformity was observed in the battery pack heated by the forced convective heating. Comparatively, the AC heating can warm the battery evenly due to the internal heating mechanism, but it took a longer time.