Bimetallic phosphide wrapped in hierarchically structured P, N co-doped porous carbon nanocatalysts for enhanced rechargeable Li[sbnd]O2 batteries

Abstract

Recently, transition-metal phosphides (TMPs) cathode materials possess tremendous prospects for lithium‑oxygen batteries (LOBs). However, designing highly efficient TMPs cathode materials achieving long-cycling stability still faces numerous obstacles. The hierarchical porous carbon is expected to be a remarkable substrate for transition-metal composites because of its high specific surface area and superior electrical conductivity. Herein, NiCoP@PNC hybrid catalysts consisting of NiCoP nanoparticles and heteroatom-doped carbon skeleton were prepared via simple freeze-drying and high-temperature pyrolysis methods. The NiCoP@PNC composites with a high specific surface area and rich interior porosity can effectively accelerate charge transfer and enhance electrocatalytic activity. Compared with either Co2P@PNC and PNC electrodes, the NiCoP@PNC cathode delivers an enhanced specific capacity of 14,028.1 mAh g−1 at 100 mA g−1. The NiCoP@PNC catalytic LOBs can reach 196 cycles with the fixed capacities of 500 mAh g−1 at 200 mA g−1 due to the increased electron transfer efficiency and improved electrochemical reaction kinetics. This approach provides a facile method to prepare TMP-based composite materials for developing high-performance LOBs.