Charge-Mediated Interfacial Coupling in Carbon Nanotube Conductive Networks Enables Concurrent Mechanical Reinforcement and SEI Stabilization for Durable SiOx Anodes

Abstract

Micron-scale SiOx anodes suffer from electrical contact failure due to volume expansion, which severely compromises their long-term electrochemical stability and practical viability. Herein, we establish charge-mediated interfacial coupling in CNT conductive networks through tannic acid anchoring on aminated CNTs. This anchoring originates from ionic pairing between protonated amines and phenolic oxygen anions, enriching the CNT surface with abundant polyphenolic hydroxyls (Ph–OH) and protonated amines (–NH3+) as active donor sites. The resulting multi-type hydrogen-bonding interactions with charge-assisted strengthening provide solid-solid interfacial reinforcement across the CNT-binder and CNT-SiOx interfaces, stabilizing electrical contacts and preserving structural integrity under repeated volumetric stress. Moreover, local modulation of the LiPF6 ion-association environment by the charged and polyphenolic interfacial sites on TNC favors the evolution of a thin, LiF-rich solid electrolyte interphase (SEI) with balanced organic/inorganic composition. The resultant electrode delivers a capacity retention of 81.82% after 450 cycles at 0.3 C. An Ah-level NCM811|| SiOx pouch cell employing this electrode delivers improved cycling stability with a capacity retention of 81.37% after 100 cycles at 1 C and retains 52.68% of its 0.1 C capacity at 4 C. This work highlights ion-pair-anchored polyphenol surface chemistry as the chemical basis for a charge-mediated interfacial coupling mechanism that concurrently reinforces solid-solid interfaces and regulates solid-liquid interphase evolution toward durable SiOx anodes.