Minimized Metal Dissolution from High-Energy Nickel Cobalt Manganese Oxide Cathodes with Al2O3 Coating and Its Effects on Electrolyte Decomposition on Graphite Anodes

High-energy nickel cobalt manganese oxides have been studied intensively as cathode materials for lithium-ion batteries. However, several hurdles need to be overcome to adopt these cathodes in commercial lithium-ion batteries. Herein, aluminum oxide (Al2O3) coating was applied to high-energy nickel cobalt manganese oxides (HE-NCM, Li1.33Ni0.27Co0.13Mn0.60O2+d) by atomic layer deposition (ALD) and its effects on HE-NCM/graphite full cells were investigated. HE-NCM/graphite full cells have better cycling performance and efficiency when HE-NCM is coated with Al2O3. ICP-MS measurements show that the Al2O3 coating can effectively prevent transition metal dissolution from HE-NCM. XPS and FT-IR analysis suggests that the surface film on HE-NCM cathodes does not change significantly with the Al2O3 coating even after 50 cycles, however the surface film on graphite anodes shows a significant change. The resistance of graphite electrodes cycled with the uncoated HE-NCM is higher than that of graphite electrodes cycled with the Al2O3-coated HE-NCM due to the increased SEI thickness. The improved cycling performance of HE-NCM/graphite cells with Al2O3 coating can be attributed to the minimized resistance increase on graphite as well as the suppression of cathode active material loss.