Performance Enhancement of 4.8 V Li1.2Mn0.525Ni0.175Co0.1O2 Battery Cathode Using Fluorinated Linear Carbonate as a High-Voltage Additive

High-capacity Li-rich layered composite oxide, xLi(2)MnO(3) center dot (1-x)LiMO2 (M = Mn, Ni, Co), is a promising candidate cathode material for high-energy electrochemical energy storage. Enabling the high-performance of high-voltage cathode relies on an electrolyte breakthrough and the solid electrolyte interface (SEI) stabilization. In this study, the 0.6Li(2)MnO(3) center dot 0.4LiNi(0.45)Co(0.25)Mn(0.3)O(2) (Li1.2Mn0.525Ni0.175Co0.1O2, LMNC) cathode is operated at 2.5-4.8 V with 5 wt% fluorinated linear carbonate, di-(2,2,2 trifluoroethyl) carbonate (DFDEC), as a high-voltage electrolyte additive, for the first time and applied to a high-energy lithium-ion battery. The cathode with DFDEC outperforms that in electrolyte only, delivering a high capacity of 250 mAhg(-1) with an excellent charge-discharge cycling stability at the rate of 0.2C. Upon the use of DFDEC, the cathode surface is effectively passivated by a stable SEI composed of DFDEC decomposition products, which inhibit a detrimental metal dissolution and structural cathode degradation. A full-cell based on the SEI-stabilized LMNC cathode and graphite anode successfully demonstrates doubled energy density (similar to 278 Whkg(-1)) compared to similar to 136 Whkg(-1) of a commercialized cell of graphite//LiCoO2 and an excellent cycling stability. (C) 2014 The Electrochemical Society. All rights reserved.