Abstract
LiNi0.5Mn1.5O4 spinel is considered one of the most promising cathodes for advanced lithium ion batteries. However, the operation potential of LiNi0.5Mn1.5O4, ~4.75 V, is beyond the high voltage limit of the state-of-art electrolyte, ~4.3 V. Here, using thin films of LiNi0.5Mn1.5O4 as a model material, we show evidence that an artificial solid electrolyte interphase (SEI) enables the use of this 5 V cathode with conventional carbonate electrolytes. A thin coating of Lipon (lithium phosphorus oxynitride) as an artificial SEI on LiNi0.5Mn1.5O4 could remedy the decomposition of the electrolyte. The thickness of the Lipon artificial SEI is optimized by balancing the protection and additional resistance. The strategy of artificial SEI on cathodes is expected to enable the wide application of other high voltage cathodes for lithium ion batteries.
