Research on the electrochemical properties of vanadium boride coated on the surface of NCM811

LiNi0.8Co0.1Mn0.1O2 (NCM811) has attracted much attention because of its high specific capacity. However, its poor electrical conductivity and the side reactions at the electrode/electrolyte interface result in unsatisfactory rate and cycling performance. A wet coating method is adapted to deposit a layer of vanadium boride (V-B) compounds on the surface of NCM811 to improve its performance. The capacity retention of [email protected] 1 V-B is increased about 15% after 500 cycles at 1 C, compared to the capacity retention of NCM. SEM and TEM images show that the thickness of the [email protected] 1 V-B coating layer is about 2.5 nm, which effectively inhibits the cracking of the surface microstructure at the cathode surface and reduces side reactions at the electrode/electrolyte interface. Thinner SEI film with less F-containing species forms on the electrode surface, less volume changes occurring the phase transition are responsible for the improved cyclability and rate capability for V-B coated NCM.