Metal-organic-framework-derived porous core/shell CoP polyhedrons intertwined with 2D MXene as anode for Na-ion storage

Transition metal phosphides (TMPs) are considered satisfactory anode candidates for sodium-ion batteries (SIBs) due to their high energy density and modest plateau. However, the TMPs anode suffers from poor cycling and rate properties owing to the negative effects of severe volumetric expansion and sluggish reaction kinetics. Herein, a novel structure of porous core/shell CoP@N-C nano polyhedral embedding on 2D MXene nanosheets (CoP@N-C/MXene) was synthesized by self-assembly and in-situ phosphorization methods. The porous CoP@NC with the unique core/shell structure benefits the infiltration of electrolytes and alleviates the volumetric change. Besides, high-conductive 2D MXene nanosheets could enhance electrical conductivity and charge transfer kinetics, and effectively inhibit CoP@N-C pulverization and agglomeration. Based on the above advantages, the as-prepared CoP@N-C/MXene anode delivers an excellent cycling capacity, outstanding rate capability and low-temperature high-rate capability. This synthetic strategy of CoP@N-C/MXene architecture can be extended to other materials which are promising for SIBs electrodes.