Unlocking double redox reaction in conductive copper-organic framework for stable zinc-ion batteries

Stable organic cathodes with multiple redox active sites can deliver the high specific capacity, rapid redox kinetics and long lifespan, promising for stable zinc storage in high-performance aqueous zinc-ion battery. Herein, a conjugated two-dimensional (2D) copper-organic framework (Cu-TABQ) with the square-planar Cu-N4 linkages is well-designed as cathode material for zinc-ion battery. The conjugated carbonyl and multivalent Cu ions electroactive centers for Cu-TABQ synergistically induce multi-electron redox chemistry, whereas the interchain hydrogen bonds and it-it stacking interactions endow a robust 2D extended layered structure in Cu-TABQ, which accelerate the intrinsic electronic conduction, ions diffusion and redox kinetics. In-situ/ex-situ spectroscopic techniques reveal a dual-site redox mechanism with co-insertion/extraction of Zn2+/H+ on Cu-TABQ cathode. These merit the zinc-ion battery based on conductive Cu-TABQ cathode with remarkably initial specific capacity of 288.6 mAh/g, superior rate capability and long-cycle stability. This work will pave new avenues for advanced organic materials via rational molecular design for aqueous zinc-ion battery and beyond.