Superior fast-charging capability of graphite anode via facile surface treatment for lithium-ion batteries

Fast-charging lithium-ion batteries (LIBs) with high energy and power density are important for the electric vehicle (EV) industry. However, graphite anode materials with high conductivity and stability still face setbacks in achieving fast charging and reach its potential. To improve the fast-charging ability of graphite, pristine graphite (PG) were treated with acid/base media, which break the bulk graphite layers into thin expanded graphite layers. Specifically, KOH etching is an effective method as it creates pores on the surfaces, facilitating the movement of Li+ ions and as well as increasing the number of sites for Li+ ion intercalation in the graphite layers. The specific capacities of acid-treated graphite (AG) and KOH-etched graphite (KG) is > 300 mAh g−1 at a current density of 100 mA g−1, which is higher than PG. Interestingly, even at high current densities, AG and KG exhibit good retention capacity in cycling. Furthermore, after long term stability tests, KG displayed the best recovery capacity at fast charging (1000 mA g−1) and slow discharging (200 mA g−1) with the highest specific capacity of 250 Ah g−1. In summary, the fast-charging ability in LIBs can be improved using surface modified graphite as the anode material.