Program: Collaborative Research Program for Alumni (CRA)

Field: Materials Engineering

Principal Investigator: Asst. Prof. Dr. Rinlee Butch M. Cervera

Sending University: University of the Philippines – Diliman (UP)

Japanese Co-Investigator: Prof. Dr. Shu YAMAGUCHI

Japanese University: The University of Tokyo

Year: 2013

Abstract:

A new lithium cobalt oxyhydroxide compound has been successfully synthesized. This new compound has been found to be related to the low temperature LiCoO2 (LT-LiCoO2) spinel structure formed at low processing temperatures. With the use of a modified sol-gel approach, this
compound with the composition of LiCo2O3(OH) can be successfully synthesized at around 150degC. Structural analyses using powder X-ray diffraction (XRD) and selected area electron diffraction (SAED) suggest a cubic-spinel structure, which is also supported by FT-IR and TG/DTA analyses. In
addition, from the TEM morphological analysis, a very fine nanograined LiCo2O3(OH) powder with an average grain size of 5 nm has been obtained. From these results, the presence of OH or water at low processing temperatures promotes a favorable formation of this structure. At higher temperatures
(>400 oC), the phase transforms to a layered high-temperature LiCoO2 (HT-LiCoO2) structure with the excess cobalt precipitated as Co3O4 as suggested by the in-situ high temperature XRD analysis.