Correlation between electronic structure, transport and electrochemical properties of a LiNi1−y−zCoyMnzO2 cathode material

Abstract

Herein, the correlation between electronic structure, transport and electrochemical properties of layered Li_xNi_1−y−zCo_yMn_zO₂ cathode material is revealed. Comprehensive experimental studies of physicochemical properties of Li_xNi_1−y−zCo_yMn_zO₂ cathode material (XRD, electrical conductivity, thermoelectric power) are supported by electronic structure calculations performed using the Korringa–Kohn–Rostoker method with the coherent potential approximation (KKR-CPA) to account for the chemical disorder. It is found that even small O defects (∼1%) could significantly modify electronic density of states DOS characteristics via the formation of extra broad peaks inside the former band gap leading to its substantial narrowing. The calculated DOS values and their changes near E_F tend to support experimental findings with irregular changes in the sign of thermoelectric power as well as the behavior of electrical conductivity curves as a function of Li content. Furthermore, the variations of the electromotive force of the Li/Li⁺/Li_xNi_1−y−zCo_yMn_zO₂ cell (for 0 < x < 1) remains in a quite good agreement with the relative variation of E_F on DOS calculated from the KKR-CPA method.