Enhancing the Electrochemical Performance of LiNi_0.70Co_0.15Mn_0.15O₂ Cathodes Using a Practical Solution-Based Al₂O₃ Coating

Ni-rich Li(Ni,Co,Mn)O2 (NCM) cathode materials have allured great research interest owing to their high energy density and relatively low costs. However, capacity fading because of parasitic side reactions, mainly occurring at the interface with the electrolyte, still hinder widespread application in advanced Li-ion batteries. Surface modification via coating is a feasible approach to tackle this issue. However, achieving uniform coatings, especially via wet chemistry methods, is challenging. In this work, a protective alumina shell on NCM701515 (70% Ni) has been prepared through reaction of surface-active -OH groups with trimethylaluminum as precursor. The coated NCM701515 shows significantly improved capacity retention over uncoated (pristine) NCM701515. Part of the reason is the lower impedance buildup with cycling due to effective suppression of adverse side reactions and secondary particle fracture. Taken together, the solution-based coating strategy described herein offers an easy to apply surface treatment to stabilize Ni-rich NCM cathode materials in next-generation LIBs.