(Fe, Ni)-ZIF-8 derived sp2-C-rich carbon as surface coating for enhancing commercial LiFePO4 performance

Abstract

LiFePO4 is the widely accepted high-performance cathode material for lithium-ion batteries with good economy and safety. Carbon encapsulation is the ordinary way to overcome its weakness of poor conductivity. In this work, nitrogen-doped carbon coating was created by growing FeNi-ZIF-8 on the lithium iron phosphate surface and then calcining at high temperature. This network structure of nitrogen-doped carbon surrounding the lithium iron phosphate is rich in both sp2-C and defectives, which promote the ions and electron conductivity throughout nanoparticles to enhance the rate performance and cycling stability of the lithium iron phosphate cathode. The results show that the synthesized LFP@NC(FeNi) composites provide a capacity of 166.6 mAh g−1 at 0.1C and 72.9 mAh g−1 at 10C, respectively. The capacity retention rate of 500 cycles at 5C is about 94.2%. The high-rate performance and cycle stability fulfill the requirements of rechargeable lithium batteries.