• Hlungwani, Donald
• Ngoepe, Phuti E.

Abstract

<jats:p>Lithium-ion batteries, comprising nanoparticulate Ni-Mn-Co (NMC) cathodes that have been used to power electric vehicles, can be improved by blending NMC with LiMn<jats:sub>2</jats:sub>O<jats:sub>4</jats:sub> (LMO). However, LMO undergoes a cubic to tetragonal phase change during charge cycling, which cracks and pulverises the material resulting in capacity fading [1]. Structural characterisation during the phase transition is the first step in mitigating capacity fading and can be challenging experimentally and computationally. The simulated amorphisation and recrystallisation method, based on empirical interatomic potentials were utilised to generate Li-Mn-O composite nanoparticles, with approximately 3000 atoms, and are amnenable to linear scaling DFT methods. The techniques was previously successfully used to study nanostructures of MnO<jats:sub>2</jats:sub> [2], with composite structures. A wealth of microstructural features such as heterostructures, point defects and grain boundaries were observed. The discharge process of the nanoparticle was simulated by lithiating the Li-Mn-O composite nanoparticle. The nanoparticle was characterized by radial distribution functions and simulated X-ray diffraction patterns (XRDs). Furthermore, the structural changes with lithiation were visualised and details of various defects, including grain boundaries could be observed from microstructures. The presence of layered and spinel components were also noted and validated by XRDs. Linear scaling density functional theory methods were used to determine voltage profiles of simulated structures.</jats:p><jats:p>References </jats:p><jats:p>1. Okumura T., Yamaguchi Y., Shikano M. and Kobayashi H., <jats:italic>J. Mater. Chem. A</jats:italic>, <jats:bold>2</jats:bold>, 8017, (2014).</jats:p><jats:p>2. Sayle, T.X.T, Kgatwane K., Ngoepe P.E. and Sayle D.C., <jats:italic>J. Mater. Chem. A </jats:italic><jats:bold>4,</jats:bold> 6456 (2016).</jats:p>

Topics

• nanoparticle
• density
• impedance spectroscopy
• grain
• phase
• x-ray diffraction
• theory
• crack
• layered
• composite
• phase transition
• density functional theory
• Lithium
• point defect