Unexpected high power performance of atomic layer deposition coated Li[Ni1/3Mn1/3Co1/3]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[Ni1/3Mn1/3Co1/3]O-2 (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 atomicscale surface engineering, the performance of Li[Ni1/3Mn1/3Co1/3]O-2 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 ultrathin 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 nextgeneration electric vehicles. (c) 2014 Elsevier B.V. All rights reserved.