Nanosized silver phosphate-based asymmetric and symmetric electrochemical capacitors for first- and second-order...

Nanoscale silver phosphate particles, with a narrow size distribution, were successfully synthesized via a complexation-mediated approach, wherein the growth and dispersion of the particles were effectively controlled by an organic stabilizing matrix. The as-prepared, organically stabilized silver phosphate was employed as an active electrode material in the fabrication of both symmetric and asymmetric electrochemical capacitors. The intrinsic electrochemical properties of the active material (silver phosphate), including redox activity, charge storage performance and kinetic characteristics, were systematically determined using a three-electrode configuration. The two-electrode systems, with both asymmetric and symmetric architectures, were utilized to evaluate the overall performance of the assembled capacitor, including parameters such as cycling stability, specific capacity, energy, power density and energy density. The fabricated asymmetric electrochemical capacitor exhibited a maximum specific capacity of 99 C g^-1 and delivered an energy density of 41 Wh kg^-1 with a corresponding power density of 865 W kg^-1 at 0.5 A g^-1. The symmetric device attained maximum power and energy densities of 2400 W kg^-1 and 3.49 Wh kg^-1 at 2.4 and 0.6 A g^-1, respectively. The Bode plot displayed the capacitance values of 3.4 and 0.45 mF for the asymmetric and symmetric electrochemical capacitors, respectively. Silver phosphate-based asymmetric and symmetric capacitors were successfully integrated into resistor-capacitor (RC) circuits and systematically evaluated for their performance in both first- and second-order low-pass filter configurations, which enabled a comparative analysis of frequency response characteristics, including attenuation behavior and phase shift.