Π‐Conjugated Polyphenols Regulate Interfacial Charge to Stabilize Lattice Oxygen in High‐Voltage Ni‐Rich Cathodes

ABSTRACT Ni‐rich layered cathodes operated at high voltages suffer from pronounced lattice‐oxygen activation during deep delithiation, which triggers oxygen release, interfacial parasitic reactions, transition‐metal destabilization, and rapid structural degradation. Here, a biomimetic interfacial‐regulation strategy is reported for high‐voltage LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathodes by introducing natural anthocyanins as π‐conjugated polyphenol additives. Enabled by their conjugated electronic framework and catechol‐derived binding sites, anthocyanin molecules preferentially accumulate at the cathode/electrolyte interface, where they regulate the local charge environment through anion coordination and interfacial electron delocalization. This molecularly regulated interphase moderates excessive lattice‐oxygen involvement during deep delithiation and suppresses irreversible oxygen‐related degradation, while promoting a thin, uniform CEI with reduced interfacial resistance and improved apparent Li + transport kinetics. As a result, gas evolution, transition‐metal dissolution, phase transition, and intragranular cracking are all effectively alleviated under high‐voltage operation. Li||NCM811 cells deliver markedly improved cycling stability, retaining 81.4% of their capacity after 200 cycles at 4.6 V and 80.0% after over 500 cycles at 4.3 V. This work establishes π‐conjugated polyphenols as a class of interfacial charge regulators for stabilizing lattice oxygen in Ni‐rich layered cathodes and offers a molecular design principle for high‐energy cathode interfaces.