Theory of the Manganese Disproportionation at the (100) Surface of LiMn2O4

Abstract

Owing to its ease of preparation, low cost and non-toxicity, LiMn2O4 (LMO) has become a promising candidate to replace LiCoO2 as a cathode material in high power Li-ion batteries. However, the performance of LiMn2O4 cathode is limited by capacity fade, particularly at high temperatures. It is believed that the capacity fade of LiMn2O4 is driven by the loss of Mn resulting from the disproportionation of surface Mn3+ with the resultant divalent Mn ions dissolving into stray moisture and electrolyte. In this work, we explore the mechanism of Mn disproportionation at the surface of LiMn2O4 using theoretical approaches, based on density functional theory to determine the mechanism of disproportionation and the effect of surface dopants. The thermodynamic driving force for disproportionation for different surface compositions will be discussed.