Ultrahigh energy density realized by a single-layer β-Co(OH)2 all-solid-state asymmetric supercapacitor

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Supercapacitors are crucial for energy storage.
• Optimizing supercapacitor performance requires advanced materials and designs.
• Atomically thin materials offer unique properties for device enhancement.

Purpose of the Study:

• To develop a novel all-solid-state asymmetric supercapacitor using atomically thin sheets.
• To optimize supercapacitor properties at the atomic level.
• To demonstrate the potential of β-Co(OH)2 single layers in high-performance energy storage devices.

Main Methods:

• Synthesis of β-Co(OH)2 single layers with five-atoms layer thickness via an oriented-attachment strategy.
• Fabrication of an all-solid-state asymmetric supercapacitor prototype.
• Electrochemical characterization to evaluate capacitance, cell voltage, energy density, power density, and cyclability.

Main Results:

• The β-Co(OH)2 single-layer electrode exhibited a large capacitance of 2028 F/g due to increased density-of-states and fully exposed hydrogen atoms.
• The asymmetric supercapacitor achieved a high cell voltage of 1.8 V and an exceptional energy density of 98.9 Wh/kg at an ultrahigh power density of 17,981 W/kg.
• The device demonstrated excellent cyclability, retaining 93.2% of its capacitance after 10,000 cycles.

Conclusions:

• Atomically thin β-Co(OH)2 single layers are promising electrode materials for high-performance supercapacitors.
• The developed all-solid-state asymmetric supercapacitor offers a viable pathway for constructing high-energy storage nanodevices.
• This work highlights the potential of atomic-level material optimization for advancing energy storage technologies.