Computational modelling studies on discharge of nanoporous spinel LiMn2O4

Porosity plays an important role in the performance of Li-ion batteries. Simulated amorphisation recrystallisation methods [1], based on molecular dynamics methods, were used to generate nanoporous LixMn2O4 spinels of approximately 25000 atoms, with different pore sizes. The resulting structures were discharged by lithiation in the concentration range x=1 to 2, and were characterised from XRDs, microstructures and mechanical properties. Generally a transition from the cubic to tetragonal spinel was observed in the range of x=1.5 to 2. In particular, at x=1.75 a broadening of XRD peaks, multiple grain boundries and a reduction in the yield stress were noted. A pore size that minimises such effects was identified together with associated heterostructures.
[1] Sayle T,X,T, Kgatwane K, Ngoepe P.E, and Sayle D.C., J. Mater. Chem. A, 4, 6465 (2016)