SYNTHESIS OF NANOSTRUCTURED LiM_0.15Mn_1.85O₄ (M = Mn, Co, Al, AND Fe) PARTICLES BY SPRAY PYROLYSIS IN A FLUIDIZED BED REACTOR

Abstract

A novel technique has been developed to directly produce fine ceramic powders from liquid solution via spray pyrolysis in a fluidized bed reactor (SPFBR). Using this technique the preparation of LiM_0.15Mn_1.85O₄ (M = Mn, Co, Al, and Fe), which are the most promising cathode materials for lithium-ion batteries, has been carried out at a superficial velocity U₀ of 0.71 m/s, a reactor temperature T of 800°C, and a static bed height L_s of 100 mm. The as-prepared powders were spherical nanostructured particles that comprised primary particles of a few tens of nanometers in size, and they exhibited a pure cubic spinel structure without any impurities in the XRD patterns. The chemical composition of as-prepared samples showed good agreement with the theoretical values that proved stoichiometric formulae of the compounds. The specific surface area of as-prepared LiM_0.15Mn_1.85O₄ (M = Mn, Co, Al, and Fe) powders decreases with increasing the static bed height in each doping metal, while the crystallite size increases with the static bed height. As a result, the as-prepared powders showed larger crystallite size and smaller specific surface area than those prepared by conventional spray pyrolysis.

Keywords:

• Cathode
• Fluidized bed reactor
• Lithium-ion batteries
• Nanostructured particles
• Spray pyrolysis
• Substituted manganese spinels

Acknowledgments

This research was partially supported by the Ministry of Education, Culture, Sports Science and Technology of Japan (Grant No. 11650774). The authors are also grateful to the staff members (Mr. A. Genseki and Mr. J. Koki) of the Center for Advanced Materials Analysis (Tokyo Institute of Technology, Japan) for the analysis of as-prepared powders.