TCNQ Confined in Porous Organic Structure as Cathode for Aqueous Zinc Battery

The rechargeable Zn ²⁺ ion batteries are promising for the sustainable energy storage device applications. Recently they have been extensively evaluated for finding new cathode material and prevention of dendrite growth at Zn plate anode. Herein we have evaluated redox active organic molecule 7,7,8,8Tetracyanoquino dimethane (TCNQ) as a cathode material for aqueous zinc battery with zinc plates as anode in 1 M ZnSO ₄ . The charging/discharging of the battery was associated with formation and deformation of Zn-TCNQ complex, which was confirmed by XRD and FTIR. The specific capacity of cathode was found to be 123.2 mAh g ⁻¹ at 100 mA current density with 96% coulombic efficiency. Whereas specific capacity at 1 A current density was found to be 60 mAh g ⁻¹ with 94% coulombic efficiency. In a cycling experiments we observed the fading of capacity with time by partial dissolution of Zn-TCNQ complex. The fading of capacity was prevented by confining TCNQ molecules inside the nano structures of newly prepared covalent organic polymers. The confinement remarkably increased the capacitance to 171 mAh g ⁻¹ at 1 A current density. As the material is readily available and the absence of toxic inflammable volatile organic electrolytes in our battery this material offers a very good choice as cathode material for zinc battery.