Facile preparation of nanoporous and nanocrystalline LiFePO4 with excellent electrochemical properties

Abstract

A modified sol-gel process for the preparation of a nanoporous LiFePO4 (LFP) cathode with a well-ordered carbon coating has been developed. The interconnected nanocrystalline LFP was fabricated by addition of sucrose at certain time intervals, which wraps the pore wall. The atomic structure of the LFP was investigated by Rietveld refinement. The surface structure and pore properties have been investigated by SEM, TEM and BET. The structure of the coated residual carbon on the LFP was analyzed by Raman spectroscopy. Lithium ion diffusion and interface properties of the LFP electrodes were investigated by CV and impedance measurements. The LFP displays a good crystal structure, high reversible capacity, good cycle stability, and high energy efficiency. It also shows excellent high rate capability with a 10 C rate capacity of up to 118.5 mA h g(-1) at the 100th cycle and a high tap density of 1.8 g cm(-3) as a cathode material.