High P-doped hollow carbon spheres for rapid sodium storage and ultra-long cycling life

The poor performance of carbon anode materials represents a significant obstacle impeding the development and application of sodium-ion batteries (SIBs). Phosphorus-doped carbon materials have attracted much attention as anodes due to their extensive interlayer spacing and robust adsorption capacity of Na⁺. Herein, we utilize the vapor-condensation method to conduct doping utilizing the diffusion of red phosphorus from the core to the periphery of the carbon spheres and thus obtain phosphorus-doped hollow carbon spheres (PHCs) with a phosphorus atom incorporation concentration of 5.02 at%. High phosphorus doping can potentially enlarge the interlayer spacing of carbon, accelerating the transmission of Na⁺. In addition, phosphorus doping enhances the adsorption energy of Na⁺. It introduces more active sites for storing more sodium, which helps to achieve high capacity and excellent rate performance. In particular, phosphorus-doped hollow carbon spheres exhibit an extraordinary performance of 147 mA h g⁻¹ at 10 A g⁻¹, accompanied by remarkable cycling durability under ultrahigh current densities. It is noteworthy that after 9200 cycles at a current density of 10 A g⁻¹, the specific capacity of the battery remains consistently at 139 mA h g⁻¹, highlighting the material's significant potential for long-term, high-performance SIBs.