A methodology to synthesize easily oxidized materials containing Li ions in an inert atmosphere

Abstract

A series of lithium-containing oxides with V³⁺ and Mn³⁺ ions are proposed as emerging high-capacity positive electrode materials for lithium-ion batteries. These oxides are typically synthesized by a calcination process in an inert atmosphere. For the successful synthesis of these materials, the strict control of oxygen partial pressure is necessary to prevent partial oxidation of materials during calcination. In this article, a simple methodology used in laboratory-scale material production, i.e., an oxygen trap by Cu foil, is described to synthesize phase pure oxides, which are easily oxidized on calcination. To demonstrate the benefit of the methodology, Li_8/7Ti_2/7V_4/7O₂ and Li_8/7Ti_2/7Mn_4/7O₂ are selected as lithium-containing oxides with V³⁺ and Mn³⁺ ions, respectively. Single phase oxides are successfully obtained from the pellets calcined with Cu foil, whereas partially oxidized phases are obtained for the pellets calcined without Cu foil. Moreover, phase-pure oxides synthesized with Cu foil show much better performance as positive electrode materials for battery applications. This methodology is also expected to be applied for material synthesis for diverse applications.