A Binary Cyclic Carbonates-Based Electrolyte Containing Propylene Carbonate and Trifluoropropylene Carbonate for 5 V Lithium-Ion Batteries

To widen the operating potential window of electrolyte used for lithium-ion batteries, a binary cyclic carbonates-based electrolyte containing propylene carbonate (PC) and trifluoropropylene carbonate (TFPC) with an optimized volume ratio has been successfully proposed. The main function of additive TFPC is to establish a stable SEI layer on graphite electrode and suppress the intercalation reaction of PC molecules. Unlike the previous works, where the TFPC/PC involved electrolyte was simply estimated at a certain volume ration and recognized as an unfavorable system, in this work, the physical properties of the electrolyte solutions with a series of volume ratios of TFPC/PC and their electrochemical performances in a graphite/Li cell and 5 V LiNi0.5Mn1.5O4/Li cell have been systematically studied. The electrolyte of 1 mol dm (3) LiPF6-TFPC/PC (1:2) is adopted as the optimized system due to its high ionic conductivity, low viscosity, broad operating potential window, wide liquid temperature range (-50 similar to 240 degrees C) and suitable film-forming property. Both the graphite and LiNi0.5Mn1.5O4 electrodes were found to exhibit high reversible capacity and superb rate performance in the optimized electrolyte, making us have a new recognition of this important binary solvent. Considering its excellent physical and electrochemical properties, we therefore anticipate that the electrolyte based on TFPC and PC is a possible candidate for future LIBs that can work in a broader temperature range and high operation potential conditions. (C) 2015 Elsevier Ltd. All rights reserved.