Tuning the properties of LiNi0.8Mn0.1Co0.1O2 via atomic layer deposition using different synthetic stages

LiNi_0.8Mn_0.1Co_0.1O₂ (NMC811) is an attractive material for high-energy-density Li-ion batteries in electric vehicles. However, it suffers from rapid capacity fading. Previous studies have shown that tuning the positive electrode material via atomic layer deposition (ALD) can enhance the electrochemical performance of the material. In this article, we introduce a novel coating method using gaseous precursors in an ALD reactor, where an AlO_x layer is deposited directly on the surface of the NMC811 precursor, followed by lithiation. The AlO_x coating is applied to the NMC811 powder substrate by exposing it to gas-phase precursors, using a conventional ALD and simplified ALD (chemical vapor deposition-like) method. It is observed that the novel methods lead to the incorporation of Al as a dopant within the bulk of NMC811, rather than forming a conformal AlO_x coating, after the final lithiation step. The optimized procedures result in positive electrode materials with higher capacity and enhanced cycling stability in both half-cell and full-cell configurations. Doping or coating was shown to mitigate transition metal dissolution, reduce side reactions between the active material and electrolyte, and improve structural stability.