Flower‐like Spherical α‐Ni(OH)2 Derived NiP2 as Superior Anode Material of Sodium‐Ion Batteries

Abstract Transition metal phosphides (TMPs) are promising anode candidates for sodium‐ion batteries, due to their high theoretical specific capacity and working potential. However, the low conductivity and excessive volume variation of TMPs during insertion/extraction of sodium ions result in a poor rate performance and long‐term cycling stability, largely limiting their practical application. In this paper, NiP 2 nanoparticles encapsulated in three‐dimensional graphene (NiP 2 @rGO) were obtained from the flower‐like spherical α‐Ni(OH) 2 by phosphating and carbon encapsulation processes. When used as a sodium‐ion batteries anode material, the NiP 2 @rGO composite shows an excellent cycling performance (117 mA h g −1 at 10 A g −1 after 8000 cycles). The outstanding electrochemical performance of NiP 2 @rGO is ascribed to the synergistic effect of the rGO and NiP 2 . The rGO wrapped on the NiP 2 nanoparticles build a conductive way, improving ionic and electronic conductivity. The effective combination of NiP 2 nanoparticles with graphene greatly reduces the aggregation and pulverization of NiP 2 nanoparticles during the discharge/charge process. This study may shed light on the construction of high‐performance anode materials for sodium‐ion batteries and to other electrode materials.