Optimized synthesis of LiFePO4 composites via rheological phase assisted method from FePO4 with acetic acid as dispersant

Abstract

LiFePO4 composites were synthesized by aqueous ball milling and carbon thermal reduction from FePO4·2H2O through a rheological phase using acetic acid as dispersant. The rheological phase assisted method using acetic acid as dispersant improved the homogeneity of mixing raw materials. Li deficiency and solid-solution Mg dopant in the lattice of LiFePO4 was created through controlled off-stoichiometry Li/Fe ratio. Li deficiency, solid-solution Mg doping and uniform carbon layer decreased electron transfer and Li-ion diffusion resistance. The optimal LiFePO4 composite exhibited a high rate capability with 153mA·h·g−1 at 1C and 111mA·h·g−1 at 20C as well as a stable capacity retention with 99% for 100 cycles at 2C and 98% for 200 cycles at 5C. The rheological phase assisted method from FePO4 with acetic acid as dispersant is a promising route for production of high quality LiFePO4 materials at a reasonable cost.