Enhanced high voltage performance of LiNi(0.5)Mn(0.3)Co(0.2)O(2) cathode via the synergistic effect of LiPO(2)F(2) and FEC in fluorinated electrolyte for lithium-ion batteries

LiNi(0.5)Mn(0.3)Co(0.2)O(2) can achieve high energy density due to its merits of high theoretical capacity and a relatively high operating voltage, but the LiNi(0.5)Mn(0.3)Co(0.2)O(2) battery suffers from capacity decay because of the unstable solid electrolyte interface on the cathode. Herein, we investigate the application of a fluorinated electrolyte composed of fluoroethylene carbonate (FEC) as a cosolvent and lithium difluorophosphate (LiPO(2)F(2)) as a salt-type additive extending the life span of the LiNi(0.5)Mn(0.3)Co(0.2)O(2) cathode. LiNi(0.5)Mn(0.3)Co(0.2)O(2) can achieve and maintain a capacity of 157.7 mA h g(−1) over 200 cycles at a 1C rate between 3.0 and 4.4 V, as well as a reversible capacity of 132.7 mA h g(−1) even at the high rate of 10C. The enhanced performance can be ascribed to the formation of the robust and protective fluorinated organic–inorganic film on the cathode, which derives from the FEC cosolvent and LiPO(2)F(2) additive and ensures facile lithium-ion transport. The synergistic effect of the cosolvent and additive to boost the electrochemical performance of LiNi(0.5)Mn(0.3)Co(0.2)O(2) cathode will pave a new pathway for high-voltage cathode materials.