Effects of nitrogen and phosphorus co-doped layering on lithium/sodium-ion storage properties of biomass-derived carbonaceous electrode materials

Abstract

Biomass materials are widely sourced and sustainable, and can be used as high-quality candidates for anodes in LIBs and SIBs. In this paper, a hierarchical porous carbon doped with nitrogen atoms and phosphorus atoms with interpenetrating channel structure was successfully obtained using agricultural waste wheat straw as a precursor. Due to its larger interlayer spacing, abundant pore structure, and more exposed active sites, it exhibits excellent rate capability in both LIBs and SIBs. For LIBs, the reversible capacity of NPWSC-700 is 1059 mA h g−1 at 0.5 C. It still exhibits unprecedented long-cycle stability at high current densities (680 mA h g−1/1200 cycles/2 C and 438 mA h g−1/2000 cycles/10 C). Meanwhile, for SIBs, the capacity is 350 mA h g−1 at 0.2 C. The specific capacities of NPWSC-700 after 1000 cycles were 182 mA h g−1 and 116 mA h g−1 at 2 C and 10 C, correspondingly. In addition, through kinetic and first-principles calculations, it is demonstrated that N, P co-doping improves Li+ (Na+) diffusion rate and adsorption capacity as well as electrical conductivity, further explaining the electrochemical properties of the material. This paper investigates a sustainable route to heteroatom-doped biomass-derived carbon for energy storage systems.