Probing inhomogeneity of electrical-thermal distribution on electrode during fast charging for lithium-ion batteries

With the emerging demands for precise control in next-generation battery managements systems (BMSs), more fundamental understanding of external characteristics for lithium-ion batteries (LIBs) is urgently required. The electrical-thermal distribution across electrode is closely coupled with cell configuration and operating conditions. Especially during fast charging, substantial temperature rise can lead to inhomogeneous in-plane thermal distribution with large thermal gradients, causing uneven local lithium (Li) plating on the anode surface, which highly undermines the safety of LIBs. In this study, aiming at probing the electrical-thermal inhomogeneity on electrode of pouch cells, distributed temperature measurements are conducted under various charge rates and ambient temperatures. A stacked layer model is established and further verified with measured anode potentials. Detailed temperature distribution inside the pouch cell and the temperature field evolution at different charge stages are thoroughly elucidated. Electrode current density distribution that results in thermal inhomogeneity is revealed, and three thermal distribution patterns coupled with various operating conditions are summarized. Then, the effects of different convection methods on electrical-thermal distribution are analysed, and enhanced convection is found to effectively reduce the thermal inhomogeneity but increase the risk for Li plating. Under uneven convection scenarios, Li plating preferably occurs on the colder region under fast charging. This study provides novel insights in electrical-thermal inhomogeneity inside LIBs, highly underpinning the smart control strategy development of next-generation BMSs.