Tortuosity Effect of Graphite Anodes for High-Performance Cylindrical Li-Ion Batteries

Abstract

This study aimed to investigate the impact of graphite tortuosity at the practical thick electrode level, which is complex and not yet well understood, on the electrochemical performance of Ni-rich NCA90 Li-ion batteries (LIBs). Various graphite anode tortuosities were examined, and it was found that low-tortuosity electrodes demonstrated better graphite utilization than high-tortuosity electrodes. In operando X-ray Diffraction and Differential Electrochemical Mass Spectrometry were also employed for charge storage mechanism and gas evolution detection, respectively. We have found that the tortuosity of the graphite electrode had an impact on the amount of Li present in the lithiated graphite phase due to diffusion limitations. However, graphite tortuosity did not have an influence on gas generation during battery operation. Safety testing conducted according to UN38.3 confirms all batteries produced in this work are safe. The study eventually demonstrated the practical use of NCA90 LIB cells optimized with varying tortuosities of thick graphite electrodes in a high-performance Lamborghini GoKart. By integrating fundamental research with practical demonstrations, this investigation is expected to contribute to further advancements in Ni-rich LIB technology.