A LiFePO₄ precursor was prepared using an aqueous mixing process combined with rheological phase technology. Due to homogeneous mixing of the starting materials, a uniform distribution of doped atoms and coated carbon in the as-prepared LiFePO₄ material was obtained. There existed a Fe³⁺ valence state of iron in the as-prepared sample. The uniform distribution of elements and small particles, and the surface phase of Fe³⁺ generated through controlled off-stoichiometry, improved the electronic conductivity. The as-prepared LiFePO₄ sample delivered a discharge capacity of 166 mA h g⁻¹ at 0.1C and presented an excellent rate capacity of 148 mA h g⁻¹ and a high potential plateau of 3.32 V at 1C. Approximately 100% capacity retention was maintained after 150 cycles at 1C or 200 cycles at 10C. This aqueous ball-milling process is a promising route for scaled-up production of LiFePO₄ materials with high quality at a reasonable cost.