Zinc Tailored Cobalt Prussian Blue Analogue (PBA) as a Prospective Candidate for Supercapacitor Applications

Supercapacitors have recently garnered copious consideration in energy storage due to their high power density, incredible stability, and long operating life. Prussian blue analogues (PBAs) have attracted researchers' attention due to the facile modulation of their atoms without bothering the existing lattice array, and their open 3D framework aids in ion conduction making it an excellent choice for developing advanced electrode materials. Herein, we report the synthesis of a trimetallic PBA by tuning the concentration of one of the metals. First, keeping the core ferricyanide structure intact, bimetallic cobalt PBA (Co-PBA) and zinc PBA (Zn-PBA) were prepared, yielding a specific capacitance of 96 and 77 F g-1, respectively, at 1 mA/cm2. However, in a trimetallic PBA with both cobalt and zinc introduced into the framework, the net specific capacitance plummeted to a higher value. The as-synthesized Zn0.04Co0.06-PBA achieved a specific capacitance of 203 F g-1 at 1 mA/cm2, which is an overall 211 and 263% increase compared to Co-PBA and Zn-PBA performance, respectively. An asymmetric device achieved a specific capacitance of 23 F g-1 at an operational voltage of 1 V. It also exhibited a capacitance retention of 84.6% after 2230 cycles with 100% Coulombic efficiency. The device yielded an energy density of 2.13 W h kg-1 and a power density of 76.75 W kg-1, which points out the fact that the developed material can truly revolutionize the field of energy storage.