Ultra‐Uniform Lithium‐Ion Transport Enabled by Supramolecular Polymeric Networks as Artificial Solid Electrolyte Interphase Layers for Highly Stable Lithium‐Ion Battery Anodes

ABSTRACT Polymer‐based artificial solid electrolyte interphase (SEI) layers have emerged as a promising solution to address the inherent limitations of silicon‐carbon nanocomposite (SCN) anodes. However, their practical implementation remains hindered by the inherent trade‐off between achieving complete surface coverage and maintaining a thin, uniform coating. This trade‐off often compromises either the electrolyte‐blocking capability or the Li‐ion transport efficiency. To overcome these challenges, we aim to enhance the ionic conductivity of the artificial SEI layer to levels comparable to liquid electrolytes, while simultaneously improving Li‐ion dissociation properties. To this end, we developed a polymer‐based supramolecular artificial SEI layer incorporating p‐phenylenediamine (pPD) as a bridging agent. The supramolecular network formed via pPD introduces robust hydrogen bonding and facilitates the formation of Li‐ion hopping channels through its benzenoid–quinoid transition. As a result, the incorporation of pPD significantly increases the ionic conductivity of PEO and PMMA polymers to 0.215 and 0.106 mS cm ⁻¹ , respectively. Furthermore, SCN anodes coated with this supramolecular SEI exhibited over fourfold improvement in cycling stability under ultra‐lean electrolyte conditions, closely mimicking commercial operating environments, compared to uncoated SCN in full‐cell configurations. This study offers a robust platform for the design of advanced artificial SEI layers tailored for high‐performance anode materials.