Interfacial Chemistry of Storage-Induced Degradation in High-Nickel Cathodes.

Interfacial instability in electrochemical systems remains a fundamental challenge, particularly in high-nickel layered oxides where reactive surfaces drive parasitic chemistry even under near-equilibrium conditions. Here, we elucidate the chemical origins of storage-induced degradation in LiNi0.8Mn0.1Co0.1O2 cathodes, showing that electrolyte decomposition and interfacial Ni dissolution are correlated processes that govern capacity loss during storage. Building on this mechanistic insight, we develop a data-driven framework for engineering cathode-electrolyte interphases (CEIs) by integrating density functional theory with machine-learning interatomic potentials. This approach enables rapid evaluation of molecular descriptors for a diverse set of electrolyte additives. Unsupervised clustering highlights lithium bis(oxalato)borate (LiBOB) and lithium trifluoromethanesulfinate as effective CEI-forming additives. Experimental validation confirms that incorporating 0.05 M LiBOB significantly stabilizes the interface, improving capacity retention from 82% to 95.5% after 28 days of storage at 60 °C, with consistent behavior in a pouch cell. Furthermore, interfacial stability is assessed using distribution-of-relaxation-time analysis, providing a practical descriptor for evaluating CEI evolution. This work establishes a generalizable, data-driven strategy for understanding and controlling interfacial reactivity in metastable electrochemical systems.