Comparison of the Electrochemical Behaviors of Stoichiometric LiNi[sub 1/3]Co[sub 1/3]Mn[sub 1/3]O[sub 2] and Lithium Excess Li[sub 1.03](Ni[sub 1/3]Co[sub 1/3]Mn[sub 1/3])[sub 0.97]O[sub 2]

Abstract

Layered oxide cathodes and have been synthesized by firing appropriate amounts of the coprecipitated hydroxides of Ni, Co, and Mn with lithium hydroxide at 900°C for 24 h and characterized by X-ray diffraction and wet chemical analysis. The lithium excess cathode was found to exhibit better cyclability and rate capability than the stoichiometric cathode up to a cutoff charge voltage of 4.6 V in lithium cells. The better electrochemical performance of the lithium excess cathode is attributed to a smaller volume change occurring during the discharge-charge cycling and a consequent suppression of lattice strain and impedance growth. © 2004 The Electrochemical Society. All rights reserved.