A method of producing Li.sub.y[Ni.sub.xCo.sub.1-2xMn.sub.x]O.sub.2 wherein 0.025.ltoreq.x.ltoreq.0.5 and 0.9.ltoreq.y.ltoreq.1.3. The method includes mixing [Ni.sub.xCo.sub.1-2xMn.sub.x]OH.sub.2 with LiOH or Li.sub.2CO.sub.3 and one or both of alkali metal fluorides and boron compounds, preferably one or both of LiF and B.sub.2O.sub.3. The mixture is heated sufficiently to obtain a composition of Li.sub.y[Ni.sub.xCo.sub.1-2xMn.sub.x]O.sub.2 sufficiently dense for use in a lithium-ion battery cathode. Compositions so densified exhibit a minimum reversible volumetric energy characterized by the formula [1833-333x] measured in Wh/L.