Zinc/Proton Hybrid Batteries Enabled by Interlayer Zn-Enolate-Coordination Bridges in Covalent Organic Frameworks

Abstract

Covalent organic frameworks (COFs) garnered significant attention as electrode materials for secondary batteries but are restricted by poor conductivity and limited capacity. Herein, we report an in situ electroreduction approach to construct permanent interlayer Zn-enolate coordination bridges in a multicarbonyl COF (namely, Tp–PTO), concurrently improving conductivity, specific capacity, and cyclability. Benefiting from a “C–O···Zn···O–C” bridging scaffold, abundant redox sites, π-conjugated structure, and smooth ion transport channels of Zn-bridged Tp–PTO COF, a Zn²⁺/H⁺ costorage process with a high capacity and fast kinetics is achieved. Moreover, a unique alternant “H⁺ → Zn²⁺ → H⁺” binding–detaching mechanism was revealed. Consequently, the Zn-bridged Tp–PTO COF demonstrated a high specific capacity (223 mAh g^–1 at 0.1 A g^–1) and long cycling stability (139.3 mAh g^–1 after 10000 cycles at 5.0 A g^–1). This work underscores the immense potential of the in situ metal coordination bridging strategy in enhancing the comprehensive performance of the COF-based electrode for advanced aqueous batteries.