Janina MolendaAGH University of Science and Technology, KrakówThe Impact Of Cathode Electronic Structure On The Parameters Of Lithium And Sodium Batteries 4th Intl. Symp. on New and Advanced Materials and Technologies for Energy, Environment and Sustainable Development Back to Plenary Lectures » | |
Abstract:The author of this work, based on her own investigations of A<sub>x</sub>MO<sub>2</sub> 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 [1-3] 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<sub>x</sub>CoO<sub>2</sub>, Na<sub>x</sub>CoO<sub>2</sub> and Li<sub>x</sub>Ni<sub>1-y-z</sub>Co<sub>y</sub>Mn<sub>z</sub>O<sub>2</sub> cathode material and explains of apparently different character of the discharge/charge curve in Li<sub>x</sub>CoO<sub>2</sub> (monotonous curve) and Na<sub>x</sub>CoO<sub>2</sub> systems (step-like curve). Comprehensive experimental studies of physicochemical properties of Li<sub>x</sub>Ni<sub>1-y-z</sub>Co<sub>y</sub>Mn<sub>z</sub>O<sub>2</sub> 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 chemical disorder. It is found that even small O defects (~1%) may significantly modify DOS characteristics via formation of extra broad peaks inside the former gap leading to its substantial reduction. Furthermore, the variations of the electromotive force of the Li/Li<sup>+</sup>/Li<sub>x</sub>Ni<sub>1-y-z</sub>Co<sub>y</sub>Mn<sub>z</sub>O<sub>2</sub> cell (for 0 < x < 1) remains in quite good agreement with the relative variation of EF on DOS calculated from the KKR-CPA method. |