Nano-sized LiFePO4/C composite with core-shell structure as cathode material for lithium ion battery

Abstract: Nano-sized composite with LiFePO<inf>4</inf>-core and carbon-shell was synthesized via a facile route followed by heat treatment at 650°C. X-ray diffraction (XRD) shows that the core is well crystallized LiFePO<inf>4</inf>. The electron microscopy (SEM and TEM) observations show that the core-shell structured LiFePO<inf>4</inf>/C composite coating with whole carbon shell layer of ∼2.8 nm, possesses a specific surface area of 51 m2 g-1. As cathode material for lithium ion battery, the core-shell LiFePO<inf>4</inf>/C composite exhibits high initial capacity of 161 mAh g-1 at 0.1 C, excellent high-rate discharge capacity of 135 mAh g-1 at 5 C and perfect cycling retention of 99.6% at 100th cycle. All these promising results should be contributed to the core-shell nanostructure which prevents collapse of the particle structure in the long-term charge and discharge cycles, as well as the large surface area of the nano-sized LiFePO<inf>4</inf>/C composite which enhances the electronic conductivity and shortens the distance of lithium ion diffusion.