Grotthuss Proton Conductive Covalent Organic Frameworks for Efficient Proton Pseudocapacitors.

Exploring new energy storage materials with both high power and energy densities has attracted great interest for electrochemical supercapacitor application. Herein, we synthesize two highly crystalline, robust, hydrophilic covalent organic frameworks (COFs) with intrinsic proton conduction by the Grotthuss mechanism. The enriched redox-active azo groups in COFs can undergo a proton-coupled electron transfer reaction for energy storage, making them ideal candidates for pseudocapacitance electrode materials. After in-situ hybridized with carbon nanotubes, the composite exhibited a high three-electrode specific capacitance of 440 F/g at the current density of 0.5 A/g, among the highest COF-based supercapacitors, and can retain 90% capacitances even after 10000 charge/discharge cycles. This work realized the first example using Grotthuss proton-conductive organic materials to create pseudocapacitors that exhibited both high power density and energy density. The assembled asymmetric two-electrode supercapacitor showed a maximum energy density of 71 Wh/kg with a maximum power density of 42 kW/kg, surpassing all reported COF-based systems.