Sample Dependence of Magnetism in the Next Generation Cathode Material LiNi0.8Mn0.1Co0.1O2

Abstract

We present a structural and magnetic study on two batches of polycrystalline LiNi0.8Mn0.1Co0.1O2 (commonly known as LiNMC811), a Ni-rich Li ion battery cathode material, using elemental analysis, X-ray and neutron diffraction, magnetometry, and polarised neutron scattering measurements. We find that the samples, labelled S1 and S2, have the composition Li1 – xNi0.9+x – yMnyCo0.1O2, with x = 0.025(2), y = 0.120(2) for S1 and x = 0.002(2), y = 0.094(2) for S2, corresponding to different concentrations of magnetic ions and excess Ni2+ in the Li+ layers. Both samples show a peak in the zero-field cooled (ZFC) dc susceptibility at 8.0(2)K but the temperature at which the ZFC and FC (field-cooled) curves deviate is substantially different: 64(2)K for S1 and 122(2)K for S2. Ac susceptibility measurements show that the transition for S1 shifts with frequency whereas no such shift is observed for S2 within the resolution of our measurements. Our results demonstrate the sample dependence of magnetic properties in LiNMC811, consistent with previous reports on the parent material LiNiO2. We further establish that a combination of experimental techniques are necessary to accurately determine the chemical composition of next generation battery materials with multiple cations.