Structural characterisation and mechanical properties of nanosized spinel LiMn2O4 cathode investigated using atomistic simulation

• Published in: Materials research bulletin 2022-02, Vol.146, p.111611, Article 111611
• Main Authors: Ledwaba, R.S., Kgatwane, K.M., Sayle, D.C., Ngoepe, P.E.
• Format: Article
• Language: English
• Subjects: Electrochemistry; Lithium ion battery; Mechanical properties; Molecular dynamics; Nanoporous material
• ISSN: 0025-5408; 1873-4227
• DOI: 10.1016/j.materresbull.2021.111611

•Amorphisation and recrystallisation technique was employed for simulated synthesis.•Composite nanosheets (2D) and nanoporous (3D) materials were generated.•XRDs and microstructures showed presence of layered-spinel intergrowths.•Bulk and nanoporous LiMn2O4 can withstand stresses associated with cycling. Mechanical stresses originate from various factors, such as mechanical load, operational vibration, diffusion during cycling, and thermal expansion coefficients. Li-ion intercalation causes lattice expansion that will impart stress on neighbouring regions and ion mechanical degradation within the layers, which leads to weaker battery performance and eventual failure. The current study reports on the advances in the simulated synthesis of nanosheet, nanoporous, and bulk ternary LiMn2O4 spinel from an atomic perspective, during which amorphisation and recrystallisation techniques were employed and the microstructures reflect the spinel and layered heterostructures. Analysis of mechanical and structural properties is carried out via stress-strain, x-ray diffraction (XRD), radial distribution functions (RDF) graphs, and molecular graphics systems before and after subjection to strain. Subsequently, molecular graphics for the nanoporous material indicated a rigid tunnel framework, whilst the bulk framework showed tilting upon compression. These structural deformations within the bulk might prevent efficient Li transport into/out of the electrode materials.