Controlling surface and interfacial properties of battery materials is key to improving performance in rechargeable Li-ion devices.

Surface reconstruction from a layered to a rock salt structure in metal oxide cathode materials is commonly observed and results in poor high-voltage cycling performance, impeding attempts to improve energy density.

Hierarchically structured LiNi0.4Mn0.4Co0.2O2 spherical powders, made by spray pyrolysis, exhibit local elemental distribution gradients that deviate from the global LiNi0.4Mn0.4Co0.2O2 composition; in particular, they are Ni-rich and Mn-poor at particle surfaces. These materials demonstrate improved Coulombic efficiencies, discharge capacities, and high-voltage capacity retention in lithium half-cell configurations. The subject powders show superior resistance against surface reconstruction due to the tailored surface chemistry, compared to conventional LiNi0.4Mn0.4Co0.2O2 materials.

This paves the way towards the development of a new generation of robust and stable high-energy NMC cathodes for Li-ion batteries.