Fast charging performance of graphite etched under mild conditions and promotion mechanism.

Fast charging of graphite is important for the popularization of electric vehicles. KOH-etched graphite with a good initial fast-charging capacity cannot be maintained during long-term fast charging. Additionally, the existing mechanism of hole creation contradicts several facts. Therefore, there is an urgent need to improve the performance and update related mechanisms of KOH-etched graphite. The etching process under mild conditions is studied, and the changes in graphite after the reaction are characterized. Three reactions involving carbon atoms at different sites are designed, and the interactions between graphite and the KOH solution are studied via quantum chemical calculations. Activated graphite (AG) is obtained by etching graphite with a KOH solution, and a nanomicro composite electrode is constructed with carbon black (CB). Only a few carbon atoms at abnormal sites can participate in the reaction under mild conditions, and a new mechanism of edge activation is provided. The AG-CB electrode with a high areal capacity exhibits excellent fast-charging capability, and a pouch cell with AG-CB and LiNi 0.5 Co 0.2 Mn 0.3 O 2 retains ∼80 % of the initial capacity after 500 cycles at a high charging rate of 3C (20 min). This cost-effective and time-efficient approach is crucial for accelerating the commercialization of high-energy-density and fast-charging batteries. Both effects jointly increase the fast-charging ability of graphite. The mild reaction conditions protect the vast majority of carbon atoms and maintain the stability of the material structure; only a few carbon atoms at abnormal positions (such as defects and edge sites) can participate in the reaction, which introduces holes on basal planes, increasing the migration paths for Li ions, and optimizes edge structures, decreasing the Li-ion intercalation impedance. [Display omitted] • A new mechanism of edge activation is proposed and supported. • Mild etching is an ideal way to enhance the fast-charging capability of graphite. • A superior KOH-etched graphite is acquired by constructing a nano-microscale structure with carbon black. • The pouch cell (>2 Ah) retains ∼80 % of the initial capacity after 500 cycles at 3C. [ABSTRACT FROM AUTHOR]