Passive radiation-modulated cellulose-based thermoelectric assemblies for efficient low-grade heat harvesting

Area of Science:

• Materials Science
• Energy Harvesting
• Sustainable Technology

Background:

• Efficient conversion of low-grade waste heat to electricity is crucial for thermoelectric energy harvesting.
• Challenges include maintaining stable temperature gradients and scalable fabrication.

Purpose of the Study:

• To develop a self-assembled, radiation-modulated thermoelectric strategy for biomass-based energy harvesting.
• To enhance thermoelectric performance by integrating radiative cooling with a cellulose nanofibril (CNF) based system.

Main Methods:

• Fabrication of a thermoelectric assembly using CNF, integrating a thermoelectric gel with a passive radiation-cooling layer.
• Characterization of solar reflectivity, temperature gradient maintenance, ionic thermovoltage, ionic figure of merit (ZT_i), and electromagnetic interference (EMI) shielding.

Main Results:

• Achieved a temperature gradient of 9.9 K leveraging radiative cooling (96.23% solar reflectivity).
• Obtained a high ionic thermovoltage of 41.01 mV K^-1 and an ionic figure of merit (ZT_i) of 1.42.
• Incorporation of MXene provided 38.18 dB EMI shielding efficiency, enhancing device stability.

Conclusions:

• The proposed strategy effectively converts low-grade waste heat into electricity by integrating radiative cooling.
• Demonstrates a scalable, eco-friendly approach for advanced thermoelectric applications.
• Highlights the significance of radiative cooling in optimizing thermoelectric conversion efficiency.