Low temperature hydrothermal synthesis of battery grade lithium iron phosphate

Abstract

Lithium ion transport through the cathode material LiFePO₄ (LFP) occurs predominately along one-dimensional channels in the [010] direction. This drives interest in hydrothermal syntheses, which enable control over particle size and aspect ratio. However, typical hydrothermal syntheses are performed at high pressures and are energy intensive compared to solid-state reactions, making them less practical for commercial use. Here, we show that the use of high precursor concentrations enables us to achieve highly crystalline material at record low-temperatures via a hydrothermal route. We produce LFP platelets with thin [010] dimensions and low antisite defect concentrations that exhibit specific discharge capacities of 150 mA h g⁻¹, comparable to material produced with higher temperature syntheses. An energy consumption analysis indicates that the energy required for our synthesis is 30% less than for typical hydrothermal syntheses and is comparable to solid-state reactions used today, highlighting the potential for low temperature hydrothermal synthesis routes in commercial battery material production.