Probing Li-ion diffusion in Li1.17Ti0.33TM0.25Mo0.25O2 (TM= Mo, Cr, Fe, Ni) with a disordered rocksalt-type structure using μ+SR

Cation-disordered rocksalt (DRS) Li-rich oxides are promising cathode materials for Li-ion batteries due to their high capacities (ca. 300 mAh/g), compositional versatility, and structural stability. However, their intrinsic Li-ion diffusion properties remain poorly understood. Conventional techniques such as NMR and impedance spectroscopy are limited by magnetic interactions and microstructural effects, complicating accurate determination of diffusion coefficients (DLi) and activation energies (Ea). We propose to investigate Li-ion transport in four cobalt-free DRS oxides containing transition metals such as Mo, Cr, Fe, and Ni. Our electrochemical data show distinct voltage profiles and cycling stability among these materials. Preliminary operando pair distribution function (PDF) and ex situ X-ray absorption spectroscopy (XAS) analyses reveal variations in short-range order (SRO) and differing degrees of reversible metal migration. We hypothesise that these structural differences influence Li-ion mobility. By combining μ⁺SR measurements with our structural data, we aim to directly determine DLi and Ea as a function of transition metal chemistry and local structure. This will allow us to correlate Li-ion transport with SRO and guide the rational design of next-generation cathodes with improved performance.