Melamine Foam-Derived N-Doped Carbon Framework and Graphene-Supported LiFePO4 Composite for High Performance Lithium-Ion Battery Cathode Material

Abstract

The relatively low ionic and electronic conductivities of lithium iron phosphate (LFP) are barriers in its utilization in electric vehicles (EVs) and smart grids. In this study, a composite of N-doped carbon-coated LFP (NCL) nanoparticles attached to a reduced graphene oxide (rGO)-wrapped N-doped carbon framework was synthesized using polydopamine as the binding agent as well as the carbon coating source and was studied as the cathode material for a lithium-ion battery. The N doped carbon framework provided a high surface area for attaching the LFP particles, pore space for Li ion migration, and network for high electrical conductivity. LFP nanoparticles were densely attached to a N-doped carbon framework due to the interaction between rGO and polydopamine. The porous and active material-interconnected structure enabled rapid lithium-ion and electron transport for improved rate performance. Furthermore, the high interaction between rGO and polydopamine could help to achieve long cyclic stability of the electrode material. The as-prepared N-doped carbon framework@rGO@N-doped carbon-coated LFP (NCFG-NCL) showed excellent cycle stability with a capacity retention of 92.2% after 500 cycles at 2 C. A remarkable rate performance with a discharge capacity of 108 mAh/g even at 20 C was also achieved. This NCFG-NCL composite offers new opportunities for high-power lithium-ion batteries.