Three-dimensional porous structure CoP/N-doped carbon nanospheres as anode for enhanced lithium storage performance

Abstract

Transition metal phosphides (TMPs) with high theoretical capacities and safe operating voltage are recognized as prospective anode materials for lithium-ion batteries (LIBs). While, the huge volume expansion and low conductivity of TMPs still restrict their applications. Engineering nanostructured composites consisting of TMPs and conductive carbon-based materials is of great importance to improve electrochemical performance. Herein, a novel and facile pyrolysis-oxidation-phosphidation approach is designed to fabricate porous nanospheres composing of CoP nanoparticles and N-doped carbon substrate. The abundant pores in CoP/N-C provide ample active sites for lithium storage and facilitate Li+ transport. The introduction of N-doped carbon substrate enhances the electrical conductivity, allowing CoP to maintain its structure during cycling. The CoP/N-C anode achieves remarkable cycle performance, maintaining an extremely stable cycle life over 2000 cycles at 5 A g−1. More importantly, the full cell consisting of CoP/N-C and LiFePO4 also exhibits a prominent cycling durability with a capacity retention of 96.5 % at 0.1 A g−1 after 150 cycles. This work proposes a simple and feasible structural engineering strategy, which can provide a new way for optimizing the electrochemical performance of conversion-type anode materials.