Toward efficient and high rate sodium-ion storage: A new insight from dopant-defect interplay in textured carbon anode materials

Abstract

Heteroatom dopants and structural defects exist concurrently and share analogous effects in modifying the electrochemical storage performance of doped hard carbon materials. However, the underlying interplay among the dopants and defects has long been ignored, which leads to controversial conclusions on the influence of dopants in defect-rich hard carbon matrix. Herein, through combined theoretical calculations and electrochemical measurements, the interplay among N, S dopants and carbon vacancy defects and its effect on hard carbon materials’ electrochemical performance for sodium-ion storage are studied. The dopant-defect interplay is corroborated to play crucial roles on the capacity and rate capability of carbon anodes, and co-doping of N, S species is demonstrated as an efficient method. Steered by the calculations, a universal in-situ texturing method is developed to synthesize the N, S dual-doped porous hard carbons with preferential features for sodium-ion batteries. The optimized hard carbon material afforded a large reversible capacity (430 ​mA ​h g⁻¹ at 0.05 ​A ​g⁻¹), an unprecedented rate performance (up to 277 ​mA ​h g⁻¹ at 5 ​A ​g⁻¹), and excellent cycling stability in sodium-ion batteries. The results in this work will inspire the rational design and fabrication of carbon materials with high capacity and superb rate capability for sodium-ion storage.