P/S Codoped Bamboo-Based Hard Carbon Anode Material Achieves High-Performance Sodium Ion Storage

Hard carbon, as a promising negative electrode material for sodium-ion batteries, is currently attracting significant attention. However, it confronts issues of low capacity and inadequate rate performance, posing hindrances and potential risks in the utilization of sodium-ion batteries. The doping of heteroatoms can improve the energy density, the rate performance, and the surface properties of sodium-ion battery anode materials. In this paper, phosphorus-sulfur codoped hard carbon materials are prepared by simple acid treatment and heat treatment with bamboo as a carbon source. Phosphorus doping induces more defects and provides more active sites for sodium storage, and sulfur doping widens the space between layers and promotes the insertion and removal of sodium ions. The prepared PHC-@S-2% has a high charge specific capacity of 320.69 mA h g^-1 at 0.1C current density, and the initial Coulombic efficiency is 66.55%. Under a current density of 2C, the charge specific capacity of 242.91 mA h g^-1 can be maintained at 235.11 mA h g^-1 after 100 cycles, and the capacity retention rate is 96.79%. Furthermore, it completes an astonishing 3000 long cycles. This work provides a simple codoping method for improving the electrochemical properties of hard carbon anode materials for sodium-ion batteries.