Understanding Aqueous Processing of Positive Electrodes for Lithium Ion Batteries: Investigation of the Interaction Mechanism of LiNi 0.8 Mn 0.1 Co 0.1 O 2 with Water via a D 2 O Treatment Approach

Aqueous processing of nickel‐rich layered oxide active materials for positive electrodes, while attractive, possesses multiple obstacles not encountered when using state‐of‐the‐art methods. One is found in structural changes at the active materials’ surface caused by the interaction with water. This study explores mechanism of interaction of water (H 2 O) on such materials via use of deuterium oxide (D 2 O) in production and comparison to a state‐of‐the‐art reference. The materials, electrode pastes, and positive electrodes were prepared with H 2 O or D 2 O and characterized regarding their properties, combined with microscopy and thermal analysis. D 2 O and H 2 O exhibited similar behavior in most metrics. Thermal analysis indicated analogous decomposition of electrodes processed with H 2 O and D 2 O, with any water detected stemming from surface residues such as hydroxides. Furthermore, the D 2 O‐processed sample showed a diverging signal from its H 2 O‐processed counterpart, indicating penetration of deuterium into the layered active material's structure. The findings offer a clear mechanistic insight into the effect of aqueous processing on nickel‐rich layered oxide materials and thus contribute to greater understanding of the hurdles to facilitate commercial viability for aqueously processed Ni‐rich layered oxide material‐based positive electrodes. Furthermore, they show the use of D 2 O as a tracking agent for water in active materials.