Investigation of the Dynamic Process of Direct Contact Pre-lithiation in Graphite Anode of Lithium-ion Batteries

Lithium-ion batteries (LIBs) experiences a significant loss of initial capacity due to the formation of solid electrolyte interface (SEI) layer for the initial charge-discharge cycle, and weaken the advantages of LIBs.Pre-lithiation (Pr-Li) has emerged as an effective strategy to compensate for such lithiuim loss in the initial cycles.We employed in-situ research techniques to investigate the direct contact Pr-Li process in graphite anode, and utilizing ultrathin lithium foil structures.Results show that the specific evolution process of direct contact Pr-Li in the graphite anode.Notably, when the lithiation state is 50%, the lithiated graphite electrode undergoes a distinct color transformation from the initial black-gray to dark blue color (LiC 18 ).It is investigated the Li transport pathway primarily involves convert into Li + followed by diffusion within the electrolyte.This intricate process eventually results in the lithiated graphite electrode was obtained.By employing ultra-thin lithium foil structure as the lithium source and exploring with insitu techniques, this study reveals the complex prelithiation dynamics inside the graphite anode using the direct contact Pr-Li method.This study contributes to more deeply understanding the mechanism of the direct contact Pr-Li, and have potential implications for the indepth study and application of pre-lithiation technology in LIBs.