Low-content Ni-doped CoS2 embedded within N,P-codoped biomass-derived carbon spheres for enhanced lithium/sodium storage

Carbonaceous materials have been promising for further advancing the lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), but suffer from a relatively low specific capacity. One effective improvement strategy by doping heteroatoms is typically used. Herein, a preparation of low-content (26.7wt%) Ni-doped CoS2 embedded N,P-codoped biomass-derived carbon spheres ((Ni0.5S0.5)S-2@NPCS) as anode materials for LIBs and SIBs is demonstrated by the sulfuration of Ni, Co salt-loaded yeast spheres. The resultant composite is endowed with the following advantages: N,P-codoped carbon sphere, low-content bimetallic (Ni0.5Co0.5)S-2 encapsulated with graphic shell. The composite indeed delivers highly enhanced electrochemical performances (a capacity of 600mAh g(-1) at 0.5A g(-1) after 450 cycles and 480mAh g(-1) at 1A g(-1) after 200 cycles) compared with the counterparts of CoS2@NPCS and pristine carbon spheres (NPCS) for LIBs. In addition, a decent reversible capacity for SIBs is achieved. The enchantment is supported by the result of electrochemical impedance spectra. The results demonstrate the biomass-derived carbon sphere can promise the preparation of promising anodes for energy storage.