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<p>Hybrid supercapacitors combine the advantages of batteries and conventional capacitors by providing a balance between high energy density and high-power density. In this study, a three-dimensional octahedral framework of β-Na₂MnP₂O₇ (NMP) is investigated as a positive electrode material for aqueous sodium-ion hybrid capacitors. X-ray diffraction (XRD) analysis confirms the formation of a triclinic crystal structure with well-defined diffraction peaks. The vibrational modes associated with P–O and P–O–P groups further verify the formation of the β-phase, as confirmed by Fourier transform infrared (FTIR) and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) reveals the presence of Na, Mn, P, and O elements with their corresponding binding energies in β-Na₂MnP₂O₇. Field-emission scanning electron microscopy (FESEM) images show a stacked plate-like morphology. The β-Na₂MnP₂O₇ // activated carbon (AC) hybrid device operates stably within a potential window of 1.5&#xa0;V in 1&#xa0;M NaOH electrolyte. The assembled cell delivers a specific capacitance of 119 F g<sup>−1</sup> at a scan rate of 2&#xa0;mV&#xa0;s<sup>−1</sup> from cyclic voltammetry and 103 F g<sup>−1</sup> at a current of 0.6&#xa0;mA from galvanostatic charge–discharge measurements. The device exhibits an energy density of 33 Wh kg<sup>−1</sup> and a power density of 245 W kg<sup>−1</sup>, along with 82% capacitance retention after 2000 charge–discharge cycles, indicating excellent electrochemical stability. Furthermore, theoretical simulations of the two-dimensional β-Na₂MnP₂O₇ || AC hybrid cell were performed using the COMSOL Multiphysics platform to analyze the electric field distribution, electric displacement field, and electric potential. These findings highlight β-Na₂MnP₂O₇ as a promising cathode material for high-performance aqueous sodium-ion hybrid capacitors.</p>

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Improved electrochemical performance of nanostructured triclinic β-Na2MnP2O7-based positive electrode for hybrid sodium-ion capacitor: experimental and theoretical analyses

  • 期刊论文

  • 发表日期：

    2026年4月15日

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  • C. Subashini,
  • S. Logeshkumar,
  • N. Priyadharsini

摘要

Hybrid supercapacitors combine the advantages of batteries and conventional capacitors by providing a balance between high energy density and high-power density. In this study, a three-dimensional octahedral framework of β-Na₂MnP₂O₇ (NMP) is investigated as a positive electrode material for aqueous sodium-ion hybrid capacitors. X-ray diffraction (XRD) analysis confirms the formation of a triclinic crystal structure with well-defined diffraction peaks. The vibrational modes associated with P–O and P–O–P groups further verify the formation of the β-phase, as confirmed by Fourier transform infrared (FTIR) and Raman spectroscopy. X-ray photoelectron spectroscopy (XPS) reveals the presence of Na, Mn, P, and O elements with their corresponding binding energies in β-Na₂MnP₂O₇. Field-emission scanning electron microscopy (FESEM) images show a stacked plate-like morphology. The β-Na₂MnP₂O₇ // activated carbon (AC) hybrid device operates stably within a potential window of 1.5 V in 1 M NaOH electrolyte. The assembled cell delivers a specific capacitance of 119 F g−1 at a scan rate of 2 mV s−1 from cyclic voltammetry and 103 F g−1 at a current of 0.6 mA from galvanostatic charge–discharge measurements. The device exhibits an energy density of 33 Wh kg−1 and a power density of 245 W kg−1, along with 82% capacitance retention after 2000 charge–discharge cycles, indicating excellent electrochemical stability. Furthermore, theoretical simulations of the two-dimensional β-Na₂MnP₂O₇ || AC hybrid cell were performed using the COMSOL Multiphysics platform to analyze the electric field distribution, electric displacement field, and electric potential. These findings highlight β-Na₂MnP₂O₇ as a promising cathode material for high-performance aqueous sodium-ion hybrid capacitors.