Core–Shell LiFePO4/Carbon-Coated Reduced Graphene Oxide Hybrids for High-Power Lithium-Ion Battery Cathodes

Abstract

Core-shell carbon -coated LiFePO4 nanoparticles were hybridized with reduced graphene (rGO) for high- power lithium-ion battery cathodes. Spontaneous aggrega- tion of hydrophobic graphene in aqueous solutions during the formation of composite materials was precluded by em- ploying hydrophilic graphene oxide (GO) as starting tem- plates. The fabrication of true nanoscale carbon-coated LiFePO4-rGO (LFP/C-rGO) hybrids were ascribed to three fac- tors: 1) In-situ polymerization of polypyrrole for constrained nanoparticle synthesis of LiFePO4, 2) enhanced dispersion of conducting 2D networks endowed by colloid al stability of GO, and 3) intimate contact between active materials and rGO. The importance of conduc ting template dispersion was demonstrated by contrasting LFP/C-rGO hybrids with LFP/C- rGO composites in which agglomerated rGO solution was used as the starting templates. The fabricated hybrid cath- odes showed superior rate capability and cyclability with rates from 0.1 to 60 C. This study demonstrated the synergis- tic combination of nanosizing with efficient conducting tem- plates to afford facile Li+ion and electron transport for high power applications.