Enabling an intrinsically safe and high-energy-density 4.5 V-class Li-ion battery with nonflammable electrolyte

Abstract

Developing nonflammable electrolyte with a wide electrochemical window has become an urgent demand for high-energy-density and high-safe lithium-ion batteries (LIBs). Herein, a fluorinated nonflammable phosphate electrolyte is developed to construct a safe 4.5 V-class LIB (Si-SiC-C/0.35Li2MnO3·0.65LiNi0.5Mn0.5O2). The proposed fluorinated phosphate electrolyte, 0.8 M LiPF6/tris(2,2,2-trifluoroethyl) phosphate (TFEP) + 5 vol% fluoroethylene carbonate (FEC) + 5 vol% vinylene carbonate (VC), is not only completely nonflammable but also exhibits excellent oxidative/reductive stability on 0.35Li2MnO3·0.65LiNi0.5Mn0.5O2 cathode and Si-SiC-C anode. The in situ differential electrochemical mass spectrometry and X-ray photoelectron spectroscopy proved that TFEP-based electrolyte does not decompose into gases but forms a high-quality electrode-electrolyte interface on cathode surface at high working potential. The 4.5 V-class LIBs using 0.8 M LiPF6 TFEP-based nonflammable electrolyte shed some light on potential application for high-safe and low-cost larger-scale energy storage. (Figure presented.).