Low-temperature synthesis of LiNi0.5Mn1.5O4 grains using a water vapor-assisted solid-state reaction

• Published in: Journal of solid state chemistry 2018-07, Vol.263, p.94-99
• Main Authors: Kozawa, Takahiro, Hirobe, Daiki, Uehara, Kunika, Naito, Makio
• Format: Article
• Language: English
• Subjects: LiNi0.5Mn1.5O4; Lithium-ion batteries; Particle growth; Solid-state reaction; Water vapor
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2018.04.020

LiNi0.5Mn1.5O4 (LNMO) spinel is one of the candidates for the cathodes of high-energy lithium-ion batteries because of its high operating voltage of 4.7 V. However, its use at high voltages leads to the decomposition of common organic electrolytes, resulting in a cycle degradation of the batteries. Although morphological control of LNMO particles involving their size and shape is an effective approach to suppressing electrolyte decomposition, the particle growth relying on diffusion in the solids has limitations of temperature and time. Here, we report the particle growth of LNMO at a low temperature using water vapor. By heating porous Mn2O3 spheres with Li and Ni sources as a precursor, we obtain spherical LNMO particles at 500 °C in both air and water vapor. The growth of primary particles is promoted by water vapor, and consequently, the obtained LNMO cathode exhibits better properties than those observed in air. Water vapor also affects the change of shape of LNMO at higher temperatures, leading to the formation of truncated particles from the spheres. Compared to conventional heating processes, this water vapor-assisted particle growth offers a low-temperature control of particle morphologies, particularly for materials that decompose easily at high temperatures. Formation of truncated LiNi.5Mn1.5O4 particles from the spherical precursor by water vapor. [Display omitted] •Particle growth of LiNi.5Mn1.5O4 at a low temperature is achieved in water vapor.•Water vapor affects the change of shape of LiNi.5Mn1.5O4 at high temperatures.•The truncated particles are formed in water vapor.•The cathode properties of LiNi.5Mn1.5O4 obtained in water vapor are evaluated.