Wet-Chemical Synthesis of a Protective Coating on NCM111 Cathode: The Quantified Effects of Washing, Sintering and Coating

Abstract

LiNixCoyMn1-x-yO2 (NCM) cathodes, especially with high Ni content, are widely expected to keep advancing the energy density of Li-ion batteries. However, ensuring a good cycle life remains a key challenge. Applying inert protective coatings on the surface of NCMs is a common route for mitigating surface-based degradation. In this study a sustainable ethanol-based wet-chemical coating method for covering the material with Al2O3 is developed and demonstrated on NCM111. The effect of the synthesis procedure is carefully evaluated to distinguish the benefits of the protective coating from the contributions of re-sintering and removal of surface contaminants, all taking place during the synthesis of the coated material. We show that while the cycling stability is significantly improved by the material regeneration alone (65% vs 79% state-of-health after 500 charge-discharge cycles at voltage range 2.7-4.3 V vs Li/Li+), the Al2O3-coated material displays further cycle life gains, maintaining 88% of initial capacity after 500 charge-discharge cycles. This work thus demonstrates both a sustainable wet-chemical coating method and the importance of establishing a proper baseline for characterization of inert protective coatings in general. The importance of both gains further prominence with the transition to inherently less stable higher Ni content NCMs. © 2024 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. --//-- This is an open-access article Liga Maskova, Reinis Ignatans, Arturs Viksna, Anatolijs Sarakovskis, Maris Knite and Gints Kucinskis, "Wet-Chemical Synthesis of a Protective Coating on NCM111 Cathode: The Quantified Effects of Washing, Sintering and Coating", Journal of the Electrochemical Society, 2024, Volume 171, Issue 10, Article number 100520, doi: 10.1149/1945-7111/ad8483 published under the CC BY 4.0 licence.