Polyphenol-Gated Composite Electrolytes with Enhanced Cross-Phase Lithium-Ion Transport for Solid-State Lithium Batteries

A biomimetic polyphenol-gated strategy is proposed to promote interfacial Li⁺ - selective transport in composite solid electrolytes by chemically bonding the polymer matrix and ceramic nanofibers. The polyphenol interlayers serve as the chemical gates with -OH and -NH groups to immobilize lithium salt anions and carbonyl groups to coordinate Li⁺, thus lowering the energy barrier and promoting rapid Li⁺ transport at interface. The assembled Li||LiFePO₄ batteries exhibits an impressive capacity of 151.6 mAh g^-1 and long lifespan over 600 cycles. Solid-state lithium (Li) batteries offer high-energy density and operational safety but face sluggish Li⁺ transport in polymer/ceramic composite solid-state electrolytes. Herein, we propose a bioinspired polyphenol-gated interfacial engineering that mimics ion-selective protein channels to enhance Li⁺-selective transport across the polymer-ceramic interface. Polyphenols such as polydopamine, poly-tannic acid, and poly-gallic acid chemically couple La_0.56Li_0.33TiO₃ ceramic nanofibers and glycidyl polyether matrix. Within this interface, carbonyl groups selectively coordinate Li⁺ and facilitate directional migration. On the other hand, hydroxyl and amino groups immobilize anions via hydrogen bonding. This chemical gating nearly doubles interfacial Li⁺ concentration and boosts transference number to 0.68. The corresponding Li||LiFePO₄ battery exhibits stable cycling over 600 cycles with 85.5% capacity retention at 1 C, while the pouch cell delivers reliable operation under mechanical stress caused by bending and puncturing. This work demonstrates that polyphenol-gated interfaces are essential for promoting selective and efficient cross-phase Li⁺ transport for high-performance solid-state lithium-metal batteries.