Interface-Engineered 2H-MoS₂/MXene Heterostructures for High-Performance Ammonium-Ion Hybrid Supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous ammonium-ion hybrid supercapacitors (AAHSCs) are gaining attention for their eco-friendly nature and electrochemical properties.
• 2D transition metal carbides and nitrides (MXenes) are excellent cathode materials for AAHSCs due to high conductivity and redox activity.
• MXene restacking hinders ion accessibility and rate performance in AAHSCs.

Purpose of the Study:

• To develop advanced cathode materials for AAHSCs by addressing MXene restacking.
• To enhance ion transport and electrochemical performance in AAHSCs.
• To create novel interfacial heterostructures for improved energy storage.

Main Methods:

• In situ growth of vertically aligned 2H-MoS2 nanosheets on Ti3C2Tx MXene to form heterostructures (HS-2H-MS@MXene).
• Characterization of the heterostructure interface and its built-in electric field (BIEF).
• Electrochemical testing of HS-2H-MS@MXene as a single electrode and in a full-cell configuration with activated carbon (AC).

Main Results:

• The HS-2H-MS@MXene heterostructure exhibits a stable BIEF, accelerating charge transport.
• Vertically aligned 2H-MoS2 nanosheets improve surface area and NH4+ storage sites, reducing charge transfer resistance.
• Single electrode: 722.13 F g-1 capacitance at 1 A g-1, 61.6% rate capability at 20 A g-1, 90.1% stability after 5,000 cycles.
• Full cell (with AC): 51.1 Wh kg-1 energy density at 750.6 W kg-1 power density, 95.6% capacitance retention after 10,000 cycles.

Conclusions:

• The developed HS-2H-MS@MXene heterostructure is a promising cathode material for high-performance AAHSCs.
• The strategy of vertically aligned nanosheets on MXene effectively enhances ion accessibility and electrochemical performance.
• This work offers a viable approach for designing next-generation supercapacitor cathode materials.