Gigantic and Continuous Output Power in Ionic Thermo-Electrochemical Cells by Using Electrodes with Redox Couples

Area of Science:

• Energy Conversion and Storage
• Materials Science
• Electrochemistry

Background:

• Ionic thermo-electrochemical cells (TECs) face low heat-to-electricity conversion efficiency due to ion confinement in liquid electrolytes.
• Current TECs often exhibit slow ion transport rates when redox processes occur near, but not on, the electrode surface.

Purpose of the Study:

• To enhance TEC performance by integrating redox couples directly onto electrode surfaces.
• To maximize ion mass transport efficiency and improve heat-to-electricity energy conversion.

Main Methods:

• Developed a discontinuous interfacial modification strategy using carbon cloth/iron (II/III) phytate as symmetric electrodes.
• Utilized a gelled electrolyte with a polyacrylamide matrix and phytic acid to promote selective ion diffusion.
• Established a synergistic combination of thermodiffusion and electrode redox reactions.

Main Results:

• Achieved a high output voltage of 0.4 V.
• Demonstrated an excellent instantaneous output power density of 20.26 mW m⁻² K⁻².
• Recorded a record-high 2-hour output energy density of 2451 J m⁻² at a temperature difference of 15 °C (30 °C - 15 °C).
• Attained an ultrahigh Carnot-relative efficiency of 1.12%.

Conclusions:

• Integrating redox couples directly onto electrode surfaces significantly enhances TEC performance.
• The developed TEC design offers a promising pathway for efficient continuous power supply from heat.
• The synergistic approach combining thermodiffusion and surface redox reactions is key to achieving high energy conversion efficiencies.