uSR study of low temperature magnetism in Li NMC 811

LiNi0.8Mn0.1Co0.1O2 (Li NMC 811) is a next generation Li ion battery cathode material. We are investigating the magnetic properties of Li NMC 811 to track the changes in local ordering of the magnetic ions and changes in oxidation state as a function of electrochemical cycling. Here we focus on pristine Li NMC 811 which contains S=1/2 Ni3+, S=1 Ni2+, S=3/2 Mn4+ and S=0 Co3+. In addition it is prone to off-stoichiometry and Li/Ni site disorder due to which some Ni2+ spins occupy the Li+ layers. It is not possible to determine the nature of the magnetic ground state for such complex systems with multiple magnetic species from bulk magnetic susceptibility measurements alone. uSR is the ideal probe to study the local magnetism and we propose to carry out zero field and weak transverse field uSR measurements to investigate the sample-dependent nature of the magnetic ground state.