High performance of LiFePO4 with nitrogen and phosphorus dual-doped carbon layer for lithium-ion batteries

Abstract In recent years, LiFePO4 is considered to be a promising cathode material for lithium-ion batteries (LIBs) and has attracted increasing attention due to its good thermal stability, safety and environmental friendliness compared with layered cathode materials (such as Li[NixCoyMnz]O2). However, the low electrical conductivity and slow lithium-ion diffusion hampers the use of LFP in applications. Herein, we report a creative and facile method for fabricating nitrogen and phosphorus dual-doped carbon-coated LiFePO4 (LFP@NPC) via the pyrolysis of egg yolk. Egg yolk is a widely available and low-cost raw material and is used in this work as both the carbon precursors and the dopant source. LFP@NPC materials produced by one-step pyrolysis of egg yolk were systematically studied by various characterization techniques. The obtained results show that LFP@NPC has smaller uniform particle sizes, better grain-to-grain electrical contact, and faster diffusion of both electrons and lithium ions. As expected, the LFP coating with 1 mL egg yolk exhibits a high discharge capacity of 150.2 mAh g−1 at 1 C and ultralong cycle performance with only 0.016% capacity fading rate per cycle in 300 cycles at 2 C. Therefore, we suggest that the LFP@NPC composite is a promising cathode material with high performance for LIBs.