Aromatic polyamine-grafted and nitrogen-doped graphene anodes boosting surface-dominated sodium storage

Abstract

The development of high-capacity and long-cycled carbon anodes for sodium-ion batteries is limited by the sluggish kinetics of surface capacitive adsorption that dominates the rate capability. Covalently grafted functionalization and heteroatom doping have emerged as promising strategies to overcome these issues. Herein, a one-step hydrothermal strategy is proposed to simultaneously achieve 1,2,4-Triaminobenzene (Tri) grafting and nitrogen doping of reduced graphene oxide (Tri-N-rGO). The formation of an amide bond between Tri and rGO enables structural stability and enriches additional adsorption sites around Tri. A high edge-nitrogen ratio of 82.5% facilitates the enhancement of surface-dominated sodium adsorption. Consequently, the Tri-N-rGO electrode delivers a high discharge specific capacity of 340.3 mAh g⁻¹ at 0.1 A g⁻¹ and a superior rate capability of 180.3 mAh g⁻¹ at 5 A g⁻¹. More importantly, it displays excellent long-term cycling stability and delivers a reversible capacity of 175.1 mAh g⁻¹ after 5000 cycles even at 5 A g⁻¹. The enhanced surface-controlled adsorption mechanism is further demonstrated by multiple measurements and theoretical calculations. The corresponding full cell can still deliver a high specific capacity of 172.7 mAh g⁻¹ after 500 cycles at 0.5 A g⁻¹. This study opens a new avenue for designing high-performance carbon for high-rate sodium-ion batteries and confers the extension to other secondary batteries.