Colloidal Crystal Templating to Produce Hierarchically Porous LiFePO4 Electrode Materials for High Power Lithium Ion Batteries

Porous LiFePO4 has been prepared via a solution-based templating technique. Beads of poly(methyl methacrylate) were synthesized with diameters of 100, 140, and 270 nm and used to form colloidal crystal templates to produce LiFePO4, which featured pores spanning from 10 to 100 nm. The use of colloidal crystal templates allowed an examination of the effects of pore size on the electrochemical properties. The templated LiFePO4 samples were fully characterized using SEM, TEM, XRD, Rietveld analysis, and nitrogen sorption prior to electrochemical testing. The materials with the largest pores, around 100 nm diameter, gave the best discharge capacities, with 160 mA h g−1 at 0.1C and 115 mA h g−1 at 5C being achieved. This compares with a theoretical discharge capacity of 170 mA h g−1.