CoP Nanoparticles Intertwined with Graphene Nanosheets as a Superior Anode for Half/Full Sodium-Ion Batteries

Conversion-type CoP is a promising anode candidate for sodium-ion batteries (SIBs) thanks to their abundant resources and high theoretical capacity. However, the low reversible capacity and inferior cycle life are two major obstacles that limit its practical application in SIBs. Herein, cobalt-based metal-organic framework derived CoP nanoparticles coupled with reduced graphene oxide (RGO) composite (CoP/RGO) has been successfully prepared. The optimized CoP/RGO presents a high reversible capacity (258.6 mAh g(-1) at 0.1 A g(-1)), superior rate capability (173 mAh g(-1) at 2 A g(-1)) and extraordinary durability (155 mAh g(-1) at 0.5 A g(-1) after 500 cycles with the per cycle capacity decay rate of only 0.065 %). In addition, electrochemical analyses reveal fast reaction kinetics and high surface capacitive contribution in CoP/RGO composite, which can be responsible for the excellent performance. Furthermore, the CoP/RGO//Na3V2(PO4)(3) sodium-ion full cells are assembled successfully and display an initial charge capacity of 231.1 mAh g(-1) at 0.1 A g(-1). Considering the low cost and great electrochemical performances, this work may provide some new opportunities for the synthesis of activity anode materials for SIBs.