Structural Stability of Lithium Extracted Li1-xNi1-yCoyO2

R.V. CHEBIAM; F. PRADO; A. MANTHIRAM

Saint Louis

Encuentro; The American Ceramic Society’s 102nd Annual Meeting and Exposition; 2000

The American Ceramic Society

The structural stability of Li1-xNi1-yCoy02 (0 < y < 0.3) cathodes has been investigated by chemically extracting lithium with an oxidizing agent from the layered LiNi1-yCoy02 and heating the samples at moderate temperatures (50-150°C). The delithiated samples experience a decrease in the c/a ratio at temperatures as low as 50 °C due to a migration of the Ni3+/4+ ions from the Ni layer to the Li layer. The change in the c/a ratio increases with increasing temperature and degree of delithiation, but decreases with increasing cobalt content y. Thus the Li1-xCoC>2 cathodes are structurally stable while the Li-xNi1-yCoy02 cathodes suffer from a structural instability at moderate temperatures.