MoS₂ @Polyaniline for Aqueous Ammonium-Ion Supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Ammonium-ion aqueous supercapacitors offer cost, safety, and environmental benefits.
• Optimized electrode materials are crucial for advancing ammonium-ion storage technology.

Purpose of the Study:

• To develop an optimized composite electrode for enhanced ammonium-ion storage.
• To investigate the electrochemical performance and mechanism of a MoS2@PANI composite.

Main Methods:

• Fabrication of a MoS2 and polyaniline (MoS2@PANI) composite electrode.
• Electrochemical characterization using three-electrode and symmetric supercapacitor configurations.
• Density functional theory (DFT) calculations to understand ion interaction and material properties.

Main Results:

• The MoS2@PANI composite achieved specific capacitances over 450 F g⁻¹ at 1 A g⁻¹ with 86.3% capacitance retention after 5000 cycles.
• Symmetric supercapacitors demonstrated energy densities exceeding 60 Wh kg⁻¹ at a power density of 725 W kg⁻¹.
• DFT calculations revealed enhanced NH4⁺ adsorption and conductivity due to sulfur vacancies.

Conclusions:

• The MoS2@PANI composite electrode significantly improves ammonium-ion supercapacitor performance.
• Hydrogen bond dynamics govern NH4⁺ insertion/de-insertion, distinct from Li⁺ and K⁺ ions.
• Composite engineering is a promising strategy for optimizing ammonium-ion insertion electrodes.