Structural, electronic, mechanical and thermodynamic properties of lithium-rich layered oxides cathode materials for lithium-ion battery: Computational study

Abstract

Because of their important energy density, low lithium reduction potential and compact size, lithium-ion batteries (LIBs) are the often-considered the greatest batteries ever used. Cathode materials, especially lithium-rich layered oxides are among the most appropriate candidates actualizing the remarkable energy densities of LIBs, due to their capacitance values that exceed 250 mAh/g. This study investigates the structural, electronic, mechanical and thermodynamic properties of two candidate materials: Li1.2Ni0.1Co0.2Mn0.5O2 (A) and Li1.03Ni0.77Co0.1Mn0.1O2 (B), by means of DFT-based computational simulations. The obtained results were further validated by comparison with existing experimental data. Computations were undertaken based on the Perdew-Burke-Ernzerhof (PBE) function on the Generalized Gradient Approximation (GGA) of the electron density, in the DMol3 module of Materials Studio software (BIOVIA Inc.), to determine the partial (PDOS) and total density of state (TDOS), electron density, band gap, etc. The results reveal the energy gap of material A to be 0.005 eV, as against 0.015 eV for material B, showing that A is more conductive than B. Structural and electronic defects in material B restrict its thermodynamic stability region to just 273 K, unlike A, which is thermodynamically more stable in the temperature range 273–278 K even up to 323 K, thus allowing material A to resist degradation. Moreover, material A is less resistant to changes in volume and shape at 288 and 308 K compared to material B, therefore confirming its resistance to temperature. Thus, A has a more desirable performance in terms of structural stability, reactivity, thermal stability, mechanical stability and conductivity compared to B. So, from experimental and computational results, A is a good candidate for cathode material of LIBs.