Unexpected high power performance of atomic layer deposition coated Li[Ni_1/3Mn_1/3Co_1/3]O₂ cathodes

Electric-powered transportation requires an efficient, low-cost, and safe energy storage system with high energy density and power capability. Despite its high specific capacity, the current commercially available cathode material for today's state-of-art Li-ion batteries, lithium nickel-manganese-cobalt oxide Li[Ni_1/3 Mn_1/3Co_1/3]O₂ (NMC), suffers from poor cycle life for high temperature operation and marginal rate capability resulting from irreversible degradation of the cathode material upon cycling. Using an atomic-scale surface engineering, the performance of Li[Ni_1/3Mn_1/3Co_1/3]O₂ in terms of rate capability and high temperature cycle-life is significantly improved. The Al₂O₃ coating deposited by atomic layer deposition (ALD) dramatically reduces the degradation in cell conductivity and reaction kinetics. This durable ultra-thin Al₂O₃-ALD coating layer also improves stability for the NMC at an elevated temperature (55 C). The experimental results suggest that a highly durable and safe cathode material enabled by atomic-scale surface modification could meet the demanding performance and safety requirements of next-generation electric vehicles.