Development of a high-rate-capable O3-structured 'layered' Na transition metal oxide by tuning the cation-oxygen bond covalency.

By developing a high-rate-capable O3-structured Na(Li0.05Ni0.3Si0.05Ti0.45Cu0.1Mg0.05)O2-based cathode material for Na-ion batteries, wherein partial substitution of more electronegative Si4+ for Ti4+ in the transition metal layer has weakened-cum-lengthened the Na-O bond, enlarged the 'inter-slab' spacing and, thus, enhanced the Na-transport kinetics, a design criterion has been laid-out in the above context.