We would like to propose a continuation experiment on Li-ion battery cathode material, Li(Ni,Co)O2. In previous experiments in 2013 and 2014, we attempted muSR technique to practical cathode sheets of Li-ion battery to observe Li-ion diffusion in Li(Ni,Co)O2. We tried to extract a signal from Li(Ni,Co)O2, although the effect of Al foil in cathode sheets was not completely removed. As a result, we obtained dyanmic signals due to both Li-ion diffusion in Li(Ni,Co)O2 and muon diffusion in Al foil. We estimated Li-ion diffusion coefficient for Li(Ni,Co)O2, of which the composition dependence is comparably different from that measured for powder samples of other typical battery materials. It is important to verify the characteristic behavor for Li(Ni,Co)O2. In addition, this experiment will help for us to confirm that muSR can be applied to in situ measurements of Li-ion battery.