Improving Li-ion Batteries with Nanoscale Surface Research

Energy storage system requires an efficient, low-cost, and safe with high energy density and high power capability. Despite its high specific capacity, the current commercially available important cathode material for today’s state-of-art Li-ion batteries, lithium nickel-manganese-cobalt oxide Li[Ni1/3Mn1/3Co1/3]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 nanoscale surface engineering, we significantly improved the performance of Li[Ni1/3Mn1/3Co1/3]O2 with respect to rate capability and its cycle-life at high temperature. The Al2O3 coating deposited by atomic layer deposition (ALD) dramatically reduces the degradation in cell conductivity and reaction kinetics through suppressing the dissolution of Ni, Mn, and Co from surface of the NMC. This durable ultra-thin Al2O3-ALD coating layer also improves stability for the NMC at an elevated temperature (55oC). 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.