Atomic layer deposition of solid-state electrolyte coated cathode materials with superior high-voltage cycling behavior for lithium ion battery application

LiNi1/3Co1/3Mn1/3O2 (NMC) is a highly promising cathode material for use in lithium ion batteries; unfortunately, its poor cycling performance at high cutoff voltages hinders its commercialization. In this study, for the first time, we employ atomic layer deposition (ALD) to coat lithium tantalum oxide, a solid-state electrolyte, with varying thicknesses on NMC in an attempt to improve battery performance. Our results indicate that utilization of a solid-state electrolyte as a coating material for NMC significantly improves performance at high cutoff voltages but is strongly dependent on coating thicknesses. Our investigation revealed that a thicker coating proved to be beneficial in preventing cathode material dissolution into the electrolyte and aided in maintaining the microstructure of NMC. Consequently, a thicker ALD coating resulted in increased electrochemical impedance of the cathode. The results of this study indicate that an optimized coating thickness is needed in order to strike a balance between maintaining structural stability while minimizing electrochemical impedance. The coating thicknesses are functionally specific, and for the best improvement of a cathode, a particular coating thickness should be sought.