Cellulose ionic conductor with tunable Seebeck coefficient for low-grade heat harvesting

Area of Science:

• Materials Science
• Sustainable Energy
• Polymer Chemistry

Background:

• Thermoelectric materials are crucial for harvesting waste heat into electricity, promoting sustainable energy solutions.
• Conventional thermoelectric generators often rely on petroleum-based resources, posing environmental concerns.
• Natural polymers offer a sustainable alternative for thermoelectric applications.

Purpose of the Study:

• To fabricate efficient thermoelectric generators (TEGs) using cellulose as a natural polymer matrix.
• To explore the potential of cellulose-based ionic conductors for energy harvesting and storage.
• To develop flexible thermoelectric harvesters for practical applications like body heat recovery.

Main Methods:

• Cellulose ionic conductors were synthesized using cellulose as a hydrogel matrix and cellulose solvents as electrolytes.
• p-type and n-type thermoelectric generators were fabricated based on the cellulose ionic conductors.
• A flexible module-type thermoelectric harvester with 10 pairs of p-n legs was assembled.

Main Results:

• The cellulose-based TEGs exhibited Seebeck coefficients of 2.61 mV/K (p-type) and -1.33 mV/K (n-type) due to specific cation-cellulose interactions.
• A cellulose TEG-based supercapacitor demonstrated high specific capacitance and thermal charging capabilities, with a maximum power density of 0.42 mW/m².
• The flexible thermoelectric harvester generated 0.42 V under a 13 K temperature gradient, suitable for body heat harvesting.

Conclusions:

• Cellulose ionic conductors are effective for developing sustainable thermoelectric generators and supercapacitors.
• These materials enable efficient waste/biological heat conversion for applications in temperature monitoring and control.
• The developed flexible thermoelectric harvester demonstrates potential for wearable energy harvesting and self-powered devices.