Performance Enhancement of 4.8 V Li_1.2Mn_0.525Ni_0.175Co_0.1O₂Battery Cathode Using Fluorinated Linear Carbonate as a High-Voltage Additive

High-capacity Li-rich layered composite oxide, x Li 2 MnO 3 ·(1-x) LiMO 2 (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 ·0.4LiNi 0.45 Co 0.25 Mn 0.3 O 2 (Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O 2 , 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 (∼278 Whkg −1 ) compared to ∼136 Whkg −1 of a commercialized cell of graphite//LiCoO 2 and an excellent cycling stability.