New Li-ion Battery Evaluation Research Based on Thermal Property and Heat Generation Behavior of Battery

We do a new Li-ion battery evaluation research on the effects of cell resistance and polarization on the energy loss in batteries based on thermal property and heat generation behavior of battery. Series of 18650 cells with different capacities and electrode materials are evaluated by measuring input and output energy which change with charge-discharge time and current. Based on the results of these tests, we build a model of energy loss in cells' charge-discharge process, which include Joule heat and polarization heat impact factors. It was reported that Joule heat was caused by cell resistance, which included DC-resistance and reaction resistance, and reaction resistance could not be easily obtained through routine test method. Using this new method, we can get the total resistance R and the polarization parameter eta. The relationship between R, eta, and temperature is also investigated in order to build a general model for series of different Li-ion batteries, and the research can be used in the performance evaluation, state of charge prediction and the measuring of consistency of the batteries.