MOF-derived porous carbon inlaid with MnO2 nanoparticles as stable aqueous Zn-ion battery cathodes

Cathodes derived from metal-organic framework materials offer unique advantages in terms of improved structural reversibility and electron conduction efficiency. Nevertheless, the capacity contribution of cathodes based on the carbon framework system has not been clearly discussed or is controversial in aqueous batteries. In this essay, we have uncovered the capacity contribution arising from the adsorption of anions/cations onto the carbon surface by examining the bonds of the carbon and the details of unsteady voltage in the CV/GITT during the discharge. Benefiting from the synergistic contribution of the double-layer capacitance and pseudocapacitance, Zn/C-MnO2 exhibits excellent long-cycling stability and fast kinetics. To the best of our knowledge, this is the first report on the ion adsorption-based double layer effect in aqueous zinc ion batteries. Such a capacity contribution mechanism, and a renewed knowledge of the discharge mechanism, will contribute to the development of high-performance aqueous zinc ion batteries.