Confined Red Phosphorus in Edible Fungus Slag-Derived Porous Carbon as an Improved Anode Material in Sodium-Ion Batteries

Red phosphorus (RP) as the anode material for the sodium-ion battery (SIB) possesses a high energy density, but the poor electronic conductivity and huge volume change during Na+ insertion/extraction restrict its application. In this work, the edible fungus slag-derived porous carbon (PC) is adopted as a carbon matrix to combine with RP to form PC@RP composites through a facile vaporization-condensation approach. The conductive porous carbon architecture improves the transfer of electron and Na+ in the composite. The robust carbon framework together with the chemical bonding between PC and RP effectively buffer the huge volumetric change of RP. As a result, the PC@RP composite material delivers a specific capacity of 655.1 mA h g-1 at 0.1 A g-1 with a capacity retention of 87% after 100 charging/discharging cycles. In particular, the full SIB assembled with P2-Na2/3Ni1/3Mn1/3Ti1/3O2 as the cathode material and PC@RP as the anode material exhibits a specific capacity of 77.3 mA h g-1 (based on the mass of cathode material) at 0.5 C, and 85% capacity is retained after 100 charging/discharging cycles.