Ab initio molecular-dynamics studies on Li x Mn 2 O 4 as cathode material for lithium secondary batteries

Structural and dynamic properties of spinel LiMn 2 O 4 are investigated firstly from ab initio molecular-dynamics (MD) calculations. This method included all the interactions among the ions so that more reliable results have been obtained comparing with the conventional classical MD simulations. Full MD simulations are performed to study the structural and diffusive properties while selective MD simulations are performed to study the migration energy barrier of Li ions. Results indicate that Li ions tend to take one fcc sub-lattice in the Li 0.5 Mn 2 O 4 crystal. The migration energy barriers of Li ions from one 8 a site to another nearest-neighbor 8 a site are about 0.23 and 0.61 eV for LiMn 2 O 4 and Li 0.5 Mn 2 O 4 , respectively.