Cathode Electronic Structure Impact on Lithium and Sodium Batteries Parameters

The author of this work basing on her own investigations of A x MO 2 cathode materials (A = Li, Na; M = 3d) has demonstrated that the electronic structure of these materials plays an important role in the electrochemical intercalation process. The proposed electronic model of intercalation is universal and has outstanding significance with regard to tailoring the properties of electrode materials to the most efficient application in Li-ion and Na-ion batteries. The paper reveals correlation between electronic structure, transport, and electrochemical properties of layered Li x CoO 2 , Li x Ni 1 − y − z Co y Mn z O 2 and Na x CoO 2 cathode material and explains of appar-ently different character of the discharge/charge curve in Li x CoO 2 (monotonous curve) and NaxCoO 2 systems (step-like curve). Comprehensive experimental studies of physicochemical properties of Li x Ni 1 − y − z Co y Mn z O 2 cathode material (XRD, electrical conductivity, and 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 chemical disorder. It is found that even small oxygen defects (~1%) may significantly modify DOS characteristics via formation of extra broad peaks inside the former gap leading to its substantial reduction.