Dataset: Investigation of Energy Storage Performance and Cycling Stability of Electrochemically Synthesized PANI–ZnFe2O4 Electrodes

Conducting polymer-metal oxide hybrids are promising electrode materials for supercapacitors, yet achieving a balance between high capacitance and long-term stability remains challenging. In this work, polyaniline (PANI) - zinc ferrite (ZnFe₂O₄) composites were synthesized by in situ electrochemical polymerization of aniline with controlled deposition duration for ZnFe2O4-nanoparticle incorporation. Structural and spectroscopic characterization confirmed uniform dispersion of ZnFe2O4 within the polymer matrix and the formation of fibrous nanostructures. Electrochemical analysis revealed a progressive enhancement of redox activity and charge storage with increasing ZnFe2O4 content. The optimized composite exhibited a specific capacitance of up to 1402 F g⁻¹ at 1 A g⁻¹, together with an energy density of 141.9 Wh kg⁻¹ and a power density of 404.9 W kg⁻¹. When assembled into a symmetric supercapacitor, the PANI-zinc ferrite composite retained 97.6% of its initial capacitance after 10,000 charge–discharge cycles. Electrochemical impedance spectroscopy further indicated that structural degradation under accelerated aging is primarily associated with particle and polymer chain cracking/breaking, leading to increased mass transport resistance, thereby reducing the energy storage capability.

Conducting polymer-metal oxide hybrids are promising electrode materials for supercapacitors, yet achieving a balance between high capacitance and long-term stability remains challenging. In this work, polyaniline (PANI) - zinc ferrite (ZnFe₂O₄) composites were synthesized by in situ electrochemical polymerization of aniline with controlled deposition duration for ZnFe2O4-nanoparticle incorporation. Structural and spectroscopic characterization confirmed uniform dispersion of ZnFe2O4 within the polymer matrix and the formation of fibrous nanostructures. Electrochemical analysis revealed a progressive enhancement of redox activity and charge storage with increasing ZnFe2O4 content. The optimized composite exhibited a specific capacitance of up to 1402 F g⁻¹ at 1 A g⁻¹, together with an energy density of 141.9 Wh kg⁻¹ and a power density of 404.9 W kg⁻¹. When assembled into a symmetric supercapacitor, the PANI-zinc ferrite composite retained 97.6% of its initial capacitance after 10,000 charge–discharge cycles. Electrochemical impedance spectroscopy further indicated that structural degradation under accelerated aging is primarily associated with particle and polymer chain cracking/breaking, leading to increased mass transport resistance, thereby reducing the energy storage capability.

The research data is structured with respect to the Figure numbers in the manuscript.
Figure_2: Synthesis of PANI and PANI@ZF composite electrodes
Figure_3: XRD-analysis of all synthesized composite electrodes and reference sprectra
Figure 4: FT-IR data of all synthesized composite electrodes
Figure 5: SEM images of PANI and PANI@ZF composite electrodes
Figure 6: Electrochemical analysis: a) CV of PANI, PANI@ZF1, PANI@ZF2 and PANI@ZF3; b) PANI@ZF3 at different scan rates; c) tafel plots of PANI@ZF3; d) specific capcitances calculated by CV spectra of PANI, PANI@ZF1, PANI@ZF2 and PANI@ZF3; e) Galvanostatic charge/discharge experiments of PANI, PANI@ZF1, PANI@ZF2 and PANI@ZF3; f) galvanostatic charge/discharge experiments at different current densities for PANI@ZF3; g) specific capacitances for PANI, PANI@ZF1, PANI@ZF2 and PANI@ZF3 at different current densities
FIgure 7: a) Ragone diagram of PANI@ZF3 as symmetrical supercapacitor; b) coulombic efficiency of PANI@ZF3 at different current densities during galvanostatic charge/discharge
Figure 8: a) Charge/Discharge cycles of PANI@ZF3 at different cycling numbers; b) specific capacitance of PANI@ZF3 over varying cyclinc numbers
Figure 9: Impedance spectra at different SOC: a) SOC = 0; b) SOC = 50; c) SOC = 100; d) comparison of all spectra
Figure 10: Impedance spectra at different cycle numbers: 2000, 4000, 8000, and 10000 cycles
Figure to table A2: EDX spectra of PANI, PANI@ZF1, PANI@ZF2 and PANI@ZF3