Improved fast charging capability of graphite anodes via amorphous Al2O3 coating for high power lithium ion batteries

Abstract

Fast charging capability is a high demand feature of lithium ion batteries used in electric vehicles; however, current lithium ion battery technology does not meet electric vehicles fast charging requirements. In this work, it demonstrates that surface modification of graphite using amorphous Al2O3 is an efficient way to improve the fast charging capability of graphite anode materials for lithium ion batteries. Surface-engineered graphite with 1 wt % Al2O3 exhibits a reversible capacity of about 337.1 mAh g(-1), even at a high rate of 4000 mA g(-1), corresponding to 97.2% of the capacity obtained at a current density of 100 mA g(-1). Full cell tests adopting LiCoO2 cathodes and Al2O3-coated graphite anodes confirm that the introduction of amorphous Al2O3 can improve the fast charging capability of graphite anode materials. Wettability tests and electrochemical impedance spectroscopy analysis reveal that this fast charging improvement results from the increased electrolyte wettability on the graphite that is induced by the Al2O3 layer on its surface. Our approach is a practical means to attaining enhanced fast charging capabilities from graphite anode materials for use in high power lithium ion batteries.