The constant global demand on energy resources, coupled to a diminishing supply of fossil fuels, has pushed Li-ion battery cathode development to the research forefront. Questions remain as to the mechanisms ongoing in these materials as lithium departs and enters the structure upon discharge and charge cycles. The current proposal seeks to use muons to study the lithium diffusion in a series of LiMPO4 nanoparticles. We are particularly interested in probing the link between particle morphology and resulting lithium behaviour. To do this, we will examine three samples: layered LiFePO4, nanocrystalline LiFePO4 and nanorods of LiFe0.5Mn0.5PO4. We also want to investigate any differences between materials on the nanoscale and their bulk counterparts.