Electrochemical properties of sodium manganese oxide/nickel foam supercapacitor electrode material

Abstract

Sodium manganese oxide (Na_xMnO₂) is supported on nickel foam (NF) substrate to prepare electroactive Na_xMnO₂/NF electrode material. Na_xMnO₂ as sodium ion pre-intercalation compound is formed through solid phase reaction of MnO₂ and NaOH with optimal mole ratio of 1:2 and calcination treatment at 700 °C for 5 h. Na_xMnO₂ shows lower Warburg diffusion impedance and charge transfer resistance than MnO₂. Na_xMnO₂/NF shows much higher current response than MnO₂/NF due to predominant reversible redox reaction of Na_xMnO₂. The reversible intercalation/deintercalation of sodium ion at the deep interlayer of Na_xMnO₂ contributes to Faradaic capacitance. MnO₂/NF and Na_xMnO₂/NF reveal capacitance decay from 18.5 to 4.2 F g⁻¹ and from 133.2 to 65.7 F g⁻¹ in 0.5 M Na₂SO₄ electrolyte when current density increases from 0.2 to 2.0 A g⁻¹, indicating respective capacity retention of 22.7% and 49.3%. Na_xMnO₂/NF exhibits higher capacitance and better rate capacitance retention than MnO₂/NF, presenting the promising supercapacitor energy storage.

Keywords:

• Sodium manganese oxide
• electrochemical properties
• capacitance
• supercapacitor electrode material

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

The work was supported by the Fundamental Research Funds for the Central Universities and the Priority Academic Program Development of Jiangsu Higher Education Institutions.