Phase transition driven tough hydrogel ionic thermoelectric cell with giant thermopower

Area of Science:

• Materials Science
• Energy Storage
• Polymer Chemistry

Background:

• Quasi-solid ionic thermoelectric (i-TE) cells offer a promising alternative to batteries for wearable electronics.
• Current i-TE cells face limitations due to low thermopower, hindering practical applications.

Purpose of the Study:

• To develop a novel temperature-responsive supramolecular hydrogel for enhanced i-TE cell performance.
• To investigate the mechanism of improved thermopower generation through volume phase transition.

Main Methods:

• Synthesis of a P(N-acryloylsemicarbazide-co-acrylic acid) (PNA) hydrogel.
• Characterization of the hydrogel's mechanical and electrochemical properties.
• Fabrication and testing of PNA-based i-TE cells under a temperature gradient.

Main Results:

• The PNA hydrogel exhibits a volume phase transition (VPT) that enhances ion entropy difference, redox efficiency, and ionic thermodiffusion.
• A single PNA i-TE cell achieved a thermopower of 2.04 V with a 50 K temperature difference.
• Key performance metrics reached: Seebeck coefficient (S_e) of 40.9 mV K^-1, specific output power density of 35.2 mW m^-2 K^-2, and a figure of merit (ZT) of 1.33.

Conclusions:

• The developed PNA hydrogel represents a significant advancement in polymer-based i-TE cell technology.
• This hydrogel offers a pathway for high-performance, environmentally friendly, and cost-effective thermoelectric power generation for wearables.