Co-Doping Strategies to Improve the Electrochemical Properties of LixMn2O4 Cathodes for Li-Ion Batteries

Four novel cathode electrode materials with improved material properties have been derived from the Lithium Manganese Oxide spinel using co-doping strategies. Specifically, Aluminum, Nickel, Magnesium, and Yttrium were selected as the primary dopant to replace a fraction of Mn3+ (5 %), and S2- was selected as the secondary dopant to replace 1 % of O2-. A combination of quantum mechanics and molecular dynamics was used to study the fracture mechanics of the new materials for various State of Charge values, and improved performance is validated with experimental data. The results show that lattice constant values for all the doped structures decrease by 1.87 %-2.07 %. Overall, with co-doping, the diffusion properties improved, and activation energy required for Li+ vacancy migration reduced (0.21-0.25 eV). We conclude that with reduced inter-atomic distance, the overall life of the LMO spinel can be improved. The Computational Fluid Dynamics simulations to study the macro-scale behaviour of these new materials shows a reduction in intercalation induced stress and heat generation.