Abstract: Research on characteristics of power Li-ion batteries at extreme cold environment is the most necessary task for optimizing the battery design and the battery management system of unmanned aerial vehicle powered by Li-ion batteries in the application of polar research. A series of experiments are taken to explore the characteristics of a 12 A·h Li(NiCoMn)O2 lithium battery at extreme cold environment. The results show that the available capacities of battery under different discharge rates decrease rapidly at subzero temperatures, and the attenuation rate of the maximum depth of discharge speed up with falling temperature. Meanwhile, the discharge internal resistances, especially the polarization resistance, increase substantially. The open-circuit voltage is reduced evidently. Moreover, the implement of preheating before discharging can well recover battery performance at the ambient temperatures below －40 ℃. The equilibrium temperature of battery surface remains unchanged under the same discharge rate even with changing preheating temperature. The capacity and power characteristics of battery can be recovered effectively by utilizing both the preheating and heat insulation methods at the same time.

Key words: NCM lithium ion battery; extreme cold temperature; battery characteristics; preheating; heat insulation