One-step preparation P-doped sisal fiber hard carbon: a high electrochemical performance anode material for sodium ion batteries

Biomass hard carbon materials are considered as one of the most promising anode materials for sodium ion batteries due to their cost-effectiveness and low-voltage plateau capability. In this work, phosphorus-doped sisal fiber carbon (PSFC) anode material for sodium ion batteries with rich mesopores and micropores and high capacity retention was prepared by a one-step method using sisal fiber (SF) as the raw material. The P doping greatly improved the microstructure and the electrochemical performance of SFC. The specific capacity of PSFC was as high as 335.575 mAh g⁻¹ for the first turn charge at a current density of 0.05 A g⁻¹, and still maintained at 292.55 mAh g⁻¹ after 500 cycles, with capacity retention rate as high as 87.1%. The first cycle efficiency is even improved from 19.65 to 45.55% for SFC. This work provides a simple and rapid strategy for improving the electrochemical performance of biomass hard carbon anode materials, with great potential for application.