This proposal describes a muSR experiment on Li-deficient Lix(Ni1/3Co1/3Mn1/3)O2 to determine a Li diffusion coefficient as a function of the Li content x, because muSR is a powerful technique to detect it in the compounds containing magnetic ions. The target material is developing as a positive electrode material for the next Li-ion battery on-board. In order to predict the performance of the Li-ion battery by numerical simulation, reliable physical properties of the battery materials are definitely required. In particular, we plan to prepare the Li-deficient samples by an electrochemical reaction, i.e. using a reaction in a test Li battery. For such purpose, we want to use a glove-box in ISIS to move the Li-deficient sample from a test battery to a gold O-ring sealed Ti cell. We wish to also study Li diffusion in the Li-deficient olivin-type compounds, Li0.9MPO4 with M=Fe, Co, and Ni.