Improvement of Cycleability and Rate-Capability of LiNi0.5Co0.2Mn0.3O2 Cathode Materials Coated with Lithium Boron Oxide by an Antisolvent Precipitation Method

LiNi0.5Co0.2Mn0.3O2 (NCM) particles coated with lithium boron oxide were prepared by an antisolvent precipitation method. In the antisolvent precipitation method, ethanol was used to strip off the hydrated water coordinated with lithium ions and borate ions. By the antisolvent precipitation method, the NCM particles were coated with a uniform layer of LiBO2. The capacity fading on cycling was successfully suppressed for the lithium boron oxide-coated samples. In addition, the rate capability was also improved by the coating. The lithium boron oxide coating effectively suppressed the increase of the electrode impedance associated with the electrolyte decomposition. Crack formation in the secondary particles after charge-discharge cycling was greatly inhibited for lithium boron oxide-coated NCM. It was demonstrated that the lithium boron oxide coating layer suppressed the side reactions not only on the particle surface, but also in the intergranular cracks by inhibiting the penetration of the electrolyte solution.