Kkr-CPA Calculations with Accounting for Chemical Disorder in Relation to Electrochemical Properties of the Cathode Materials for Li-Ion Batteries

Keywords: first principles calculations, Li-ion batteries,  cathode materials, electrochemical properties, transport properties, electronic structure

We focus mostly on first principles calculations of intercalation type cathode materials emphasizing the interplay between a remarkable effect of oxygen vacancy on density of states (especially in the vicinity of band gap) and relative occupancy of alkaline sites. We have used spin-polarized Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA) [1-3], which allows to account for chemical disorder (vacancy defects) both on alkaline [4] and O sites. This approach may describe the particular case of fully disordered model (treating chemical disorder as random), which keeps the same unit cell whatever the lithium (sodium) and oxygen contents. Such a model is complementary to possible ordered supercell approximants of the majority intercalated cathode material systems, which require multiplication of unit cell and modification of their symmetry.

First principles calculations with accounting for chemical disorder, if applied for the description of the process of lithium or sodium intercalation, allows to predict and design performance-related properties of cathode material, on the basis of its structural, thermal and transport properties (XRD, electrical conductivity, thermoelectric power, electronic specific heat).

Acknowledgements

The project was funded by the National Science Centre Poland (NCN) on the basis of the decision number DEC-2011/02/A/ST5/00447.

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