Easy and Scalable Syntheses of Li_1.2Ni_0.2Mn_0.6O₂

Abstract

Solid-state and sol-gel syntheses were selected as easy and scalable methods to prepare a lithium-rich cathode material for lithium-ion batteries. Among the extended family of layered oxides, Li1.2Ni0.2Mn0.6O2 was chosen for its low nickel content and the absence of cobalt. Both synthesis methods involved two heating steps at different temperatures, 600 and 900 °C. The first step is needed to decompose the metal acetates, which were selected as precursors, and the second step is needed to crystallise the material. To obtain a material with well-defined defects, the rate of heating and cooling was carefully controlled. The materials were characterised by X-ray diffraction, SEM coupled with EDS analysis, and thermal analysis and were finally tested as cathodes in a lithium semi cell. The solid-state synthesis allowed us to obtain better structural characteristics with respect to the sol-gel one in terms of a well-formed hexagonal layer structure and a reduced Li+/Ni2+ disorder. On the other hand, the sol-gel method produced a material with a higher specific capacity. The performance of this latter material was then evaluated as a function of the discharge current, highlighting its good rate capabilities.

Keywords

• Li-rich compounds
• chemical synthesis
• electrochemical properties