Construction of CoP@C embedded into N/S-co-doped porous carbon sheets for superior lithium and sodium storage

Abstract To improve the electrical conductivity and relief the large volume variation, carbon coated CoP particles were designed to homogeneously embed into porous carbon sheets, which were synthesized though a simultaneous carbonization and phosphorization method. Notably, the uniform carbon shells and porous carbon sheets constructed a tough conductive matrix to enhance the electron transfer and structural stability during charging/discharging processes. Moreover, the heteroatom doping of nitrogen and sulfur could not only introduce more active sites and defects on the carbon sheets, but also increased electrical conductivity. Owing to the unique structure, the obtained material displayed good electrochemical performance for lithium storage (638.8 mA h g−1 at 0.2 A g−1 after 500 cycles and 334.9 mA h g−1 at 10 A g−1) and sodium storage (329.4 mA h g−1 at 0.2 A g−1 after 150 cycles and 162.4 mA h g−1 at 5 A g−1). More importantly, the reaction mechanism and the ion diffusion coefficient were explored by ex-situ XRD and EIS for both LIBs and SIBs. This versatile approach may avail to predigest the tedious phosphating process to obtain high-performance TMPs-based hybrids (such as Ni2P/C) by employing other metal salts.