Redox Targeting-Based Thermally Regenerative Electrochemical Cycle Flow Cell for Enhanced Low-Grade Heat Harnessing

Area of Science:

• Materials Science
• Electrochemistry
• Energy Conversion

Background:

• Low-grade heat (<100°C) is abundant in electrical devices but largely wasted.
• Ineffective heat dissipation compromises device performance, reliability, and lifespan.
• Thermally regenerative electrochemical cycles (TRECs) offer a pathway for heat-to-electricity conversion.

Purpose of the Study:

• To demonstrate a novel redox targeting (RT)-based flow cell for efficient heat-to-electricity conversion.
• To enhance thermoelectric efficiency and introduce a cooling function.
• To investigate the pairing of Ni₀.₂Co₀.₈(OH)₂ and [Fe(CN)₆]⁴⁻/³⁻ via RT-reactions in a [Fe(CN)₆]⁴⁻/³⁻/Zn⁰/²⁺ flow cell.

Main Methods:

• Design and fabrication of a redox targeting (RT)-based flow cell.
• Utilizing solid Ni₀.₂Co₀.₈(OH)₂ and redox mediator [Fe(CN)₆]⁴⁻/³⁻ with negative temperature coefficients and identical redox potentials.
• Operation within a thermally regenerative electrochemical cycle (TREC).

Main Results:

• The RT-based flow cell achieved an unprecedented absolute thermoelectric efficiency of 3.61% in the temperature range of 25-55°C.
• The system demonstrated considerably enhanced thermoelectric efficiency compared to conventional TREC systems.
• The flow of redox fluids provided an additional cooling function to the system.

Conclusions:

• The developed RT-based flow cell is a promising technology for efficient low-grade heat-to-electricity conversion.
• This approach effectively addresses heat waste and enhances device performance.
• The combination of thermoelectric conversion and active cooling offers significant advantages for thermal management in electronic devices.