Preparation and characterization of nano-crystalline LiNi0.5Mn1.5O4 for 5 V cathode material by composite carbonate process

LiNi0.5Mn1.5O4 has been synthesized using two different synthetic methods; a sol-gel method and a composite carbonate process. LiNi0.5Mn1.5O4 obtained by the sol-gel method showed a nickel oxide impurity in the XRD diagram and two voltage plateaus at 4.1 and 4.7 V upon cycling. However, the LiNi0.5Mn1.5O4 compound obtained by the composite carbonate process exhibited a pure cubic spinel structure (Fd (3) over bar in) without any impurities and only one voltage plateau at 4.7 V in the charge/discharge curves. Furthermore, it showed an excellent cycling retention rate of over 96% in the high temperature test. The well-developed LiNi0.5Mn1.5O4 obtained by the composite carbonate process contained many spherical particles of about 3-4 mum, made up of small nano-sized particles (50-100 nm). It was a unique powder characterization and these nano-sized particles improved the cycling performance of the LiNi0.5Mn1.5O4 obtained by composite carbonate process. (C) 2002 Elsevier Science B.V. All rights reserved.