Li Diffusivity and Phase Change in LiFe0.5Mn0.5PO4: AComparative Study using Galvanostatic Intermittent Titrationand Cyclic Voltammetry

Lithium transport and phase evolution in the LiFe 0.5 Mn 0.5 PO 4 system was examined using both cyclic voltammetry and galvanostatic intermittent titration. Hydrothermal or sol–gel processing was used to synthesize LiFe 0.5 Mn 0.5 PO 4 , LiFePO 4 , and LiMnPO 4 , and electrodes made with LiFe 0.5 Mn 0.5 PO 4 or a 1:1 mass ratio of LiFePO 4 and LiMnPO 4 were produced and studied. Cyclic voltammetry was used to distinguish single- and dual-phase redox reaction regimes and also accurately measure ionic diffusivity in the dual redox couple LiFe 0.5 Mn 0.5 PO 4 system. Ionic diffusivity values extracted from galvanostatic intermittent titration data were compared to those determined via cyclic voltammetry.These results are discussed in the context of theories that explain phase transitions and diffusion in this class of materials.