High Energy Quasi-Solid-State Supercapacitors Totally Derived from Alginate Hydrogel

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-energy supercapacitors (SCs) are crucial for energy storage but often rely on expensive or unsustainable materials.
• Developing cost-effective and environmentally friendly electrode and electrolyte materials for SCs is a significant challenge.

Purpose of the Study:

• To design and fabricate high-energy quasi-solid-state SCs using solely sodium alginate (SA) as a sustainable and low-cost resource.
• To investigate the performance of N-doped porous carbon (NPC) derived from SA for enhanced supercapacitor applications.

Main Methods:

• Synthesized N-doped porous carbon (NPC) via in-situ carbonization of Ca2+-crosslinked alginate hydrogel with urea.
• Utilized SA as a binder to improve electrode wettability and reduce charge transfer resistance.
• Developed a quasi-solid-state hydrogel electrolyte based on SA and polyacrylamide for enhanced mechanical strength and ionic conductivity.

Main Results:

• The NPC exhibited hierarchical pores and high nitrogen content, facilitating ion transport and providing both electric-double-layer and pseudo-capacitance.
• The SA binder improved ion accessibility and capacitance of the carbon electrode.
• The all-in-one alginate-based SC achieved an energy density of 20.2 Wh kg−1 at 112.5 W kg−1 and maintained 95.9% capacitance over 10,000 cycles at 10 A g−1.

Conclusions:

• This work demonstrates a novel, sustainable approach to fabricating high-energy quasi-solid-state supercapacitors using biomass-derived sodium alginate.
• The developed materials and device integration strategy offer a promising pathway for manufacturing advanced energy storage devices.
• The study highlights the potential of utilizing value-added biomass resources for both material engineering and device fabrication in supercapacitors.