Surface and Interface Issues in Spinel LiNi0.5Mn1.5O4: Insights into a Potential Cathode Material for High Energy Density Lithium Ion Batteries

Spinel LiNi0.5Mn1.5O4 with high operating voltage (similar to 4.7 V vs Li/Li+), high theoretical capacity of 148 mAh g(-1), fast lithium ion diffusion kinetics, and potentially low cost is the most potential candidate material for high energy density LIBs used in plug-in hybrid electric vehicles and pure electric vehicles. However, the high operating voltage of LiNi0.5Mn1.5O4 challenges the electrochemical stability of other components in the batteries and induce diverse interfacial side reactions, leading to irreversible capacity loss, poor cycling performance, and safety issues, especially at the elevated temperatures. Thus, a basic understanding of the intrinsic surface properties of LiNi0.5Mn1.5O4 and the mechanism of interfacial interactions between each component in the electrochemical system is a critical requirement for developing substantial enhancements of LiNi0.5Mn1.5O4-based batteries. In this review, we summarize the surface/interface reactions and challenges in the whole cell system of LiNi0.5Mn1.5O4-based LIBs. Perspectives and strategies for LiNi0.5Mn1.5O4-based high energy density batteries used in PHEV/EVs are also proposed at last.