Tracing the Impact of Hybrid Functional Additives on a High-Voltage (5 V-class) SiOx-C/LiNi0.5Mn1.5O4 Li-Ion Battery System

The development of next generation high energy density lithium ion batteries (LIBs) adopting electrode materials with higher specific capacity or higher working voltage has attracted great interest. In this paper, fluoroethylene carbonate (FEC) and 1,3-propanediolcyclic sulfate (PCS) are unprecedentedly combined as hybrid functional additives to significantly improve the performances of a very challenging next-generation high voltage (5 V-class) SiOx-C/LiNi0.5Mn1.5O4 battery system, where SiOx-C composite shows a high specific capacity of 450 mAh g–1 and LiNi0.5Mn1.5O4 has a high working voltage plateau (∼4.7 V vs Li+/Li). Combining in situ differential electrochemical mass spectrometry (DEMS) technology, theoretical calculations, and conventional ex situ characterizations, it is revealed that small amounts of lithium-containing species (such as LiF, sulfate species, and organic sulfite species) with excellent electronic-insulating, ionic-conducting, and compact properties are derived from prior decomposi...