Rollable Single-Piece Thermoelectric Generators at Cryogenic Temperature Fabricated with High-performance CNT Films...

Area of Science:

• Materials Science
• Energy Science
• Nanotechnology

Background:

• Thermoelectric generators (TEGs) offer solid-state heat-to-electricity conversion, ideal for cold environments.
• Cryogenic TEGs face challenges including power factor degradation and interfacial issues from thermal expansion mismatch.
• Carbon nanotube (CNT) films present a promising alternative for thermoelectric applications.

Purpose of the Study:

• To enhance the power factor (PF) of carbon nanotube (CNT) films for cryogenic thermoelectric generators.
• To address interfacial failures in TEGs by developing flexible and structurally integral devices.
• To demonstrate the practical application of CNT-based TEGs in cold environments.

Main Methods:

• Optimized chlorosulfonic acid (CSA) doping levels in CNT films via annealing treatment.
• Characterization of doping process using spectral analysis and fitting to a pseudo-second-order kinetic model.
• Fabrication of single-piece rollable TEGs to mitigate interfacial stresses and ensure flexibility.

Main Results:

• Achieved a high power factor of 10.5 mW m^-1 K^-2 at room temperature in CNT films.
• Demonstrated a PF variation of only 20% over a temperature range of 100-298 K, outperforming many inorganic materials.
• Fabricated rollable TEGs maintained structural integrity and flexibility under cryogenic thermal cycling.
• Successfully integrated rollable TEGs into a miniature thermoelectric power station.

Conclusions:

• Optimized CSA doping in CNT films significantly boosts thermoelectric performance at room temperature.
• Rollable TEG design effectively resolves interfacial stress issues, enabling reliable cryogenic operation.
• CNT-based TEGs show significant potential for energy recovery applications in cold environments.