Simultaneous fluorination of active material and conductive agent for improving the electrochemical performance of LiNi0.5Mn1.5O4 electrode for lithium-ion batteries

High-voltage cathode materials have gained much attention as one of the promising electrode materials to increase power density of lithium ion batteries by raising the working voltage. However, the use of such high-voltage cathode materials is still challenging, because their working voltage is close to the electrochemical oxidation potential of organic electrolyte used in lithium ion batteries. In this work, we demonstrated that simultaneous fluorination of LiNi0.5Mn1.5O4 (LNMO) particles as well as conductive agent in the electrode could significantly improve the electrochemical stability of LNMO cathode. The resulting electrode showed better cycle performance both at room temperature and elevated temperature compared to both bare LNMO electrode and the electrode with only LNMO fluorinated. These results showed that direct fluorination of high voltage cathode can reduce the side reaction of high voltage cathode electrode with the electrolyte, thereby stabilizing the surface of carbon black as well as that of high voltage cathode material.