Synergistic effects of a copper-cobalt-nitroisophthalic acid/neodymium oxide composite on the electrochemical performance of hybrid supercapacitors

Abstract

Hybrid supercapacitors can produce extraordinary advances in specific power and energy to display better electrochemical performance and better cyclic stability. Amalgamating metal oxides with metal-organic frameworks endows the prepared composites with unique properties and advantageous possibilities for enhancing the electrochemical capabilities. The present study focused on the synergistic effects of the CuCo(5-NIPA)-Nd₂O₃ composite. Employing a half-cell configuration, we conducted a comprehensive electrochemical analysis of CuCo(5-NIPA), Nd₂O₃, and their composite. Owing to the best performance of the composite, the hybrid device prepared from CuCo(5-NIPA)-Nd₂O₃ and activated carbon demonstrated a specific capacity of 467.5 C g^-1 at a scan rate of 3 mV s^-1, as well as a phenomenal energy and power density of 109.68 W h kg^-1 and 4507 W kg^-1, respectively. Afterwards, semi-empirical techniques and models were used to investigate the capacitive and diffusive mechanisms, providing important insights into the unique properties of battery-supercapacitor hybrids. These findings highlight the enhanced performance of the CuCo(5-NIPA)-Nd₂O₃ composite, establishing it as a unique and intriguing candidate for applications requiring the merging of battery and supercapacitor technologies.

Fig. 1. Schematic synthesis of CuCo(5-NIPA) MOF via a sonochemical process.

Fig. 2. X-Ray diffraction patterns of (a) CuCo(5-NIPA), (b) Nd₂O₃, and (c) CuCo(5-NIPA)–Nd₂O₃. Scanning electron microscopy images along with the Energy Dispersive X-ray analysis for (d) CuCo(5-NIPA), (e) Nd₂O₃, and (f) CuCo(5-NIPA)–Nd₂O₃.

Fig. 3. Cyclic voltammograms of (a) CuCo(5-NIPA), (b) Nd₂O₃, and (c) CuCo(5-NIPA)–Nd₂O₃, (d) comparison of all three samples.

Fig. 4. Galvanostatic charge–discharge curves of (a) CuCo(5-NIPA), (b) Nd₂O₃, and (c) CuCo(5-NIPA)–Nd₂O₃, (d) comparison of the GCD curves of all three samples.

Fig. 5. (a) Specific capacities of CuCo(5-NIPA), Nd₂O₃, and CuCo(5-NIPA)–Nd₂O₃ through CV analysis. (b) Specific capacities of CuCo(5-NIPA), Nd₂O₃, and CuCo(5-NIPA)–Nd₂O₃ through GCD analysis. (c) Comparison of the electrochemical impedance spectroscopic curves for CuCo(5-NIPA), Nd₂O₃, and CuCo(5-NIPA)–Nd₂O₃ along with the fitted curves.

Fig. 6. (a) Schematic overview of the real device, (b) CV curves for activated carbon and CuCo(5-NIPA) at scan rate of 3 mV s⁻¹ in three electrode asssembly, (c) CV curve for CuCo–(5-NIPA)–Nd₂O₃//AC. (d) GCD curves for CuCo–(5-NIPA)–Nd₂O₃//AC.

Fig. 7. (a) Specific capacity through GCD analysis, (b) energy and power density of CuCo–(5-NIPA)–Nd₂O₃//AC. (c) Capacity retention and coulombic efficiency with respect to the number of cycles, (d) electrochemical impedance spectroscopy plot for CuCo–(5-NIPA)–Nd₂O₃//AC with the fitted curve.

Fig. 8. Capacitive diffusive contributions at 3, 50, and 90 mV s⁻¹ obtained through the (a)–(c) linear model and (d)–(f) quadratic model.

Fig. 9. Percentages of capacitive and diffusive contributions at various scan rates through the (a) linear model and (b) quadratic model.