High-Voltage Multi-S-Heterocyclic Covalent Organic Frameworks for Zinc-Organic Batteries with High Energy Density and Ultralong Life

Abstract

Organic p-type cathodes for Zn-organic batteries (ZOBs) have high-voltage (1.0-1.2 V), but face limited redox capacity (generally < 250 mAh g -1 ) due to low-density active sites. Here we design multi-S-heterocyclic covalent organic frameworks (S-COFs) by integrating two-electron dithiophene and three-electron trithiophene motifs via condensation reaction, which act as a new-type cathode for high-performance ZOBs. Electron-rich S-heterocyclic motifs contribute to ultralow-activation-energy electron delocalization paths (0.25 eV) and low molecular orbital energy levels (2.26 eV), thus giving a high redox voltage of 1.3 V for Zn||S-COFs battery. Furthermore, a stable 30 e -charge storage is started in dithiophene/trithiophene modules of S-COFs cathode by the (de)coordination with CF 3 SO 3 -anions, affording high capacity of 310 mAh g -1 . This remarkable combination of high voltage and capacity propels the energy density of ZOBs to a high level (403 Wh kg -1 ). Besides, the excellent anti-dissolution ability of S-COFs cathode in aqueous electrolytes extends the battery life to 60,000 cycles with 81.2% capacity retention at 10 A g -1 . Our work establishes a new paradigm to design high-voltage-capacity COFs, paving the way for next-generation high-performance ZOBs.