Crystal Orbital Overlap Population Analysis of the Capacity Fading of Metal‐Substituted Spinel Lithium Manganate LiMn2 O 4

Abstract

The capacity fading with charge‐discharge cycles, which is a problem in the practical use of spinel lithium manganate for the positive electrode material of a lithium ion rechargeable battery, is analyzed using extended Hückel band calculations. The strength of the manganese‐oxygen bond is characterized by crystal orbital overlap population (COOP) analyses. The manganese atom in lithium manganate is substituted with first‐row transition metal atoms, and the COOP is calculated and analyzed. The COOP of substituted lithium manganate is compared with the experimental data for the capacity performance in charge‐discharge cycles. Both showed very good agreement. We understand by examining the Mn‐O COOP that the suppression of capacity fading with manganese substitution in lithium manganate by Fe, Co, and Ni has relevance to an increase in the strength of the Mn‒O bond. COOP is a good index for the capacity fading with charge‐discharge cycles for the substituted lithium manganate. It is applicable to the search and examination for the best composition in the lithium manganate material system whose properties are influenced by the Mn‒O bond. © 2000 The Electrochemical Society. All rights reserved.