Interfacial stability Enhancement in Single-Crystal NCM cathodes through electronic structure optimization

Abstract

Interfacial degradation mechanisms in layered oxide cathodes represent fundamental limitations for advanced lithium-ion systems, yet systematic differentiation between bulk crystallographic strain and electronic structure-mediated interfacial instability remains challenging. Through comparative investigation of single-crystal LiNi<inf>0.6</inf>Co<inf>0.1</inf>Mn<inf>0.3</inf>O<inf>2</inf> (SC-NCM613) and LiNi<inf>0.8</inf>Co<inf>0.1</inf>Mn<inf>0.1</inf>O<inf>2</inf> (SC-NCM811) under equivalent electrochemical conditions, we demonstrate that performance differentiation originates from composition-dependent electronic structure modulation at electrode–electrolyte interfaces rather than conventional voltage constraints. Contrary to conventional expectations, single-crystal NCM613 achieves superior capacity retention (86.8 % after 1,000 cycles) at elevated voltage (4.35 V) compared to NCM811 (84.1 % retention) at reduced voltage (4.2 V), showing better stability at higher voltage. Spectroscopic characterization reveals equivalent bulk oxidation states while surface analysis demonstrates pronounced compositional dependence in frontier orbital configurations near the Fermi level. Surface-sensitive analyses reveal suppressed electron population density in SC-NCM613, substantially constraining rock-salt phase propagation depth in SC-NCM811. These findings suggest that rational electronic structure engineering provides a more effective approach than conventional compositional maximization, enabling competitive electrochemical performance while maintaining high energy density requirements. © 2025 Elsevier Ltd.