Comparison of Lattice Vibrations in LCO and LNO

The purpose of this application is to measure the Li and Ni/Co phonon modes in lithium-ion battery cathode materials, namely LiCoO2 and LiNiO2. Lithium-ion batteries that have high energy densities are enabling the transition from petrol and diesel vehicles to electric vehicles. However, the capacity we can gain from lithium-ion batteries is approaching a ceiling. New approaches to increase capacity involve substituting the Co content in the cathode for Ni. Recently published work from our group suggested that in the Ni-rich archetype LiNiO2 cathode, Ni migrates from the fully dense transition metal layer and accumulates at the surface of the particles upon charging, leaving vacancies on the transition metal site. This reduces the performance of LiNiO2. This is not observed with LiCoO2 which also has better battery cycling stability.
We wish to probe this mobility indirectly using inelastic neutron scattering. By observing the Ni phonon modes over a large temperature range we will be able to deduce whether Ni is more mobile than Co. There is also a dearth of INS experimentation on cathode materials in the literature, this study on two basic layered cathode materials will be the first step to rectify this.