Electronegative interface modification enables accelerated interfacial kinetics for lithium-ion battery anodes

Abstract

The mainstream graphite anode in lithium batteries encounters obstacles including the capacity reduction and polarization during fast-charging, which is mainly restricted by the sluggish ion transfer kinetics. Here, a universal electronegative interfacial modification strategy is proposed for improving the fast-charging performance of the graphite (Gr) anode, in which the electronegative –COOH groups on the graphite/electrolyte interface serve as a Li⁺ reservoir by the pre-adsorption of a large amount of Li⁺ through electrostatic interaction. The electron-rich interface and the enrichment of Li⁺ at the interface weaken the Li⁺-solvent interaction and provide a larger Li⁺ potential difference, thereby accelerating desolvation process and inducing the formation of inorganic-rich SEI. Therefore, the interfacial kinetics of the graphite anode was enhanced substantially by the weakened Li⁺-solvent interaction and LiF-rich SEI interface. As a result, the Gr@rGO anode with optimized –COOH groups and appropriate defects achieved a great rate performance of 192 mAh g⁻¹ at 4C, small polarization of 0.026 V, and excellent cycling stability with 97 % after 600 cycles in pouch cells. In addition, universal application of –COOH modified interphase for fast-charging performance in high-energy-density anode systems, including SiO and nano-silicon anodes, was proved to be feasible, revealing the effectiveness of the electronegative regulation for fast-charging lithium-ion battery anodes.