A research of thermal coupling model for lithium-ion battery under low-temperature conditions

Electrochemical models and equivalent circuit models have been the most common choices for simulation of the performance of lithium-ion battery. However, most models do not consider the temperature effect on the battery parameters, which leads to large simulation error when battery is under subzero operation conditions. Actually, low ambient temperature operation condition is inevitable for EVs and HEVs in cold-climate of some regions. Fundamentally, low-temperature conditions lead to a slowdown of the chemical reactions, affecting the charge-transfer kinetics and leading to low electrolyte conductivity and a decreased diffusivity of lithium ions within the negative-potential electrode(anode). In this paper, the relationship between temperature-dependent parameters and temperature at low temperatures was established. An improved model based on electrochemical-thermal coupling model (ETCM) was proposed to accurately simulate battery performance. Experimental data and the simulation of a battery proved that the proposed model can precisely simulate the battery performance at low temperatures. The results obtained in this paper are quite useful for battery management system.