Solid-State N-Type Ionic Thermoelectric Based on Polyanions Enabled by Water State Regulation via MXenes

Area of Science:

• Materials Science
• Energy Science
• Nanotechnology

Background:

• Developing ion thermoelectric (iTE) materials relies on tuning polyelectrolyte interactions for high ionic thermopower and conductivity.
• N-type polyelectrolyte development is challenging due to higher cation thermophoretic mobility compared to anions.

Purpose of the Study:

• To demonstrate a high-performance, solid-state n-type iTE material using polyanions.
• To utilize MXene nanosheets for regulating the water state in a hydrated poly(4-styrenesulfonic acid) network.

Main Methods:

• Composited MXene nanosheets with poly(4-styrenesulfonic acid) (PSSH) to form PSSH/MXene films.
• Investigated the role of MXene in transforming bound water to intermediate water and promoting proton dissociation.
• Fabricated flexible, printed devices for photo-thermoelectric applications.

Main Results:

• The PSSH/MXene composite achieved a thermopower of -15.55 mV/K and ionic conductivity of 39.03 S/m at 40% relative humidity.
• A high power factor of 9.44 mW/m·K² was obtained at 298 K.
• A printed flexible device generated -1.64 V under simulated sunlight, showcasing photo-thermoelectric potential.

Conclusions:

• MXene nanosheets effectively regulate water state, enabling high-performance n-type iTE materials based on polyanions.
• This water state regulation strategy offers a promising route for developing advanced n-type iTE materials.
• The developed material shows potential for efficient photo-thermoelectric energy conversion devices.