Abstract:

With the development of electric vehicles (EVs) and hybrid electric vehicles (HEVs), the high-power lithium-ion battery is urgently needed. Nowadays, the commercial anode material is still mainly occupied by graphite. When charging in high-rate, the diffusion of lithium is greatly restricted because of the small interlayer distance (0.335 nm) of graphite, leading to a inferior high-rate charge performance. Therefore, the preparation and evaluation of fast-charging graphite will promote the application of lithium-ion battery in the EVs or HEVs. In this paper, a kind of artificial graphite with a diameter~6.7 μm is modified by coated with hard carbon to improve the fast-charging performances. The physical properties of uncoated and coated materials are characterized by SEM and BET. And the initial charge/discharge, rate, EIS and GITT were applied to evaluate the impact of hard carbon layer on the fast-charging performances.

Key words: lithium-ion battery, artificial graphite, surface coating, fast-charging