Grotthuss Proton‐Conductive Covalent Organic Frameworks for Efficient Proton Pseudocapacitors

Abstract

Herein, we describe the synthesis of two highly crystalline, robust, hydrophilic covalent organic frameworks (COFs) that display intrinsic proton conduction by the Grotthuss mechanism. The enriched redox‐active azo groups in the COFs can undergo a proton‐coupled electron transfer reaction for energy storage, making the COFs ideal candidates for pseudocapacitance electrode materials. After in situ hybridization with carbon nanotubes, the composite exhibited a high three‐electrode specific capacitance of 440 F g−1 at the current density of 0.5 A g−1, among the highest for COF‐based supercapacitors, and can retain 90 % capacitance even after 10 000 charge–discharge cycles. This is 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−1 with a maximum power density of 42 kW kg−1, surpassing that of all reported COF‐based systems.

Advances in pseudocapacitive and battery-like electrode materials for high performance supercapacitors

“…49 On the other hand, covalent organic frameworks based on organic polymers also demonstrated good electrochemical performance as pseudocapacitive/battery-type electrode materials. 50 There are many factors affecting the performance of electrodes used in SCs, including their dimension, surface morphology, crystallinity, porosity etc. Composite electrodes with favorable characteristics regarding the ratio of components, material dimensions, porous structure, particle size and morphology are clearly more equipped to promote electron transfer, ion diffusion and redox reactions, thus increasing the performance of electrochemical devices.…”

“…49 On the other hand, covalent organic frameworks based on organic polymers also demonstrated good electrochemical performance as pseudocapacitive/battery-type electrode materials. 50…”

Connecting the dots for fundamental understanding of structure–photophysics–property relationships of COFs, MOFs, and perovskites using a Multiparticle Holstein Formalism

“…[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] Tremendous efforts are currently focused on taking advantage of the structural diversity, crystallinity, and porosity of various COF structures for potential cutting-edge applications in biomedicine and bioimaging, [46][47][48][49][50] drug and gene delivery, [51][52][53][54] gas and energy storage, [55][56][57][58] photocatalysis, 59,60 and ion conduction. 61,62 Despite the presence of intrinsic porosity, which hinders the efficient movement of charges, COFs have also found applications as semiconducting materials. [63][64][65][66][67][68][69][70][71][72] Energy and charge migration in COFs happen through the efficient transport of excitons and polarons, respectively, either along the framework backbone (i.e., through bond) or between the p-stacked layers (i.e., throu...…”

Connecting the Dots for Fundamental Understanding of Structure-Photophysics-Property Relationships of COFs, MOFs, and Perovskites using a Multiparticle Holstein Formalism

“…[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] Tremendous efforts are currently focused on taking advantage of the structural diversity, crystallinity, and porosity of various COF structures for potential cutting-edge applications in biomedicine and bioimaging, [46][47][48][49][50] drug and gene delivery, [51][52][53][54] gas and energy storage, [55][56][57][58] photocatalysis, 59,60 and ion conduction. 61,62 Despite the presence of intrinsic porosity, which hinders the efficient movement of charges, COFs have also found applications as semiconducting materials. [63][64][65][66][67][68][69][70][71][72] Energy and charge migration in COFs happen through the efficient transport of excitons and polarons, respectively, either along the framework backbone (i.e., through bond) or between the π-stacked layers (i.e., throug...…”