Expediting Sodium Energy of Hard Carbon by Cation/Anion Co-Interfering Chemistry

Abstract

Hard carbon promises commercial prospect as the anode materials of Na-ion batteries, however, it remains a huge challenge to refine the carbon microstructure for advanced sodium energy. Herein, a powerful design strategy of cation/anion co-interfering chemistry is demonstrated to expedite the sodium storage capability of resin-based hard carbon. A desirable carbon microstructure rich in closed pores and pseudographitic crystallites is synergetically developed by cation-triggered activation and anion-induced curvature of graphene nanosheets, which creates abundant active sites and fast Na⁺ diffusion channels. Impressively, the as-optimized hard carbon presents an enhanced reversible capacity of 349.3 mAh g⁻¹, outstanding rate capability of 221.6 mAh g⁻¹ at 2 A g⁻¹, as well as superior lifetime over 5000 cycles. The pore-induced kinetic characteristics and charge storage mechanism are systematically unveiled by theoretical calculations and in situ techniques. This work confers a fresh design methodology for rationally regulating the carbon microstructure for high-capacity and superb-rate sodium storage.