Analysis of polarization and thermal characteristics in lithium-ion battery with various electrode thicknesses

The increase in electrode thickness causes the higher energy density in the lithium-ion battery while the larger electric resistance and polarization will influence its thermal behaviors. Coupling electrochemical and thermal model is developed to study the effects of electrode thickness on polarization and thermal characteristics in lithium-ion battery, and to obtain specific values of polarization in positive and negative electrodes and discharge energy efficiency. The results reveal that the concentration polarization in solid matrix in positive and negative electrode will lead to larger drop amplitude in the terminal voltage curve in the initial stage and approaching to the end in discharging, respectively. With the increase in electrode thickness in discharging, the higher ratio of concentration polarization in liquid electrolyte to the total polarization occurs, and more ohmic heat than that of polarization happens, as well as the higher temperature and more non-uniformity temperature distribution take place in the battery under higher discharge rate, and the discharge energy efficiency drops with electrode. All results will help to optimize the electrode thickness in lithium-ion batteries to obtain better electrochemical-thermal performances.