Perinone-Based Ladder-Type Two-Dimensional Conjugated Covalent Organic Framework for Fast Proton Storage

Electrochemical proton storage plays an essential role in designing next-generation high-rate energy storage technologies, e.g., aqueous batteries. Two-dimensional conjugated covalent organic frameworks (2D c-COFs) are promising electrode materials, but their competitive proton and metal-ion insertion mechanisms remain elusive, and COF-based proton storage is rarely explored. Here, we report a perinone-based ladder-type 2D c-COF towards fast proton storage in both mild aqueous Zn-ion electrolyte and strong acid. We unveil that the generated C-O- groups via discharge exhibit largely reduced basicity due to the considerable pi-delocalization in perinone, thus affording the 2D c-COF a unique affinity to proton with fast kinetics. As a consequence, the 2D c-COF electrode presents outstanding rate capability up to 200 A g-1 (over 2500C). Our work reports the first example of proton storage among COFs and highlights the great potential of perinone-based 2D c-COF in future energy devices.