Molecular dynamics simulations of Li_xMn₂O₄ (0 < x ≤ 1) spinel solid solutions were carried out with the use of simple pair potentials available in the literature. The results demonstrate that computer simulations using the existing potentials with an exponential repulsion term fail to adequately reproduce appreciable Li⁺ mobility in a stable (near-zero mobility of the manganese and oxygen ions) crystalline phase. Lennard-Jones potentials make it possible to simulate such a phase at high temperatures (on the order of 1000 K).