A method for manufacturing lithium-manganese oxide powders for use in a lithium secondary battery is provided. The method includes the steps of dissolving in nitric acid a composition selected from the group consisting of: manganese oxide, manganese carbonate, or manganese to form a manganese solution, and then dissolving in the manganese solution a composition selected from the group consisting of lithium carbonate, lithium hydroxide, or lithium acetate. Glycine is added to the mixed metal solution and the mixed metal solution is dried in a vacuum dryer to form a combustible resin. The combustible resin is then ignited at room temperature and the combusted products are calcinated.