Overcapacity of Li[Ni[sub x]Li[sub 1/3−2x/3]Mn[sub 2/3−x/3]]O[sub 2] Electrodes

Abstract
Layered lithium intercalation materials with O3 structure are based on the layered compound in which and ions are replaced by On initial deintercalation of lithium, is oxidized to but further lithium removal is possible. Two mechanisms have been considered to explain the ability to overcharge, simultaneous oxygen loss or exchange the latter are generated from decomposition of the electrolyte. We show that the dominant mechanism of Li overcapacity during electrochemical charging is oxygen loss, in agreement with Dahn’s results. Some exchange does occur, however, and this is greater at 55°C than at 30°C, accounting for about 25% of the excess lithium removed at the higher temperature. In contrast to electrochemical charging, chemical removal of lithium using is accompanied by more exchange than oxygen loss. © 2004 The Electrochemical Society. All rights reserved.