Thermoelectric Performance Enhancement via Acid and Base Post-Treatments for Highly Stretchable Single-Walled Carbon Nanotube and Carboxymethyl Cellulose Composites

Deformable thermoelectrics (TEs) offer great potential for powering wearable electronics, yet conventional TE materials often lack sufficient processability and stretchability. Herein, we report the development of water-processable and highly stretchable TE films based on single-walled carbon nanotube (SWCNT) and carboxymethyl cellulose (CMC) composites, optimized through sequential acid/base post-treatments using H2SO4 and NaBH4. The dual post-treatment approach effectively modulates the conductive network morphology and the doping state of SWCNT/CMC, leading to a simultaneous enhancement in electrical conductivity and Seebeck coefficient. As a result, a maximum power factor of 245 μW m–1 K–2 and a 3-fold increase in ZT were achieved. The acid/base post-treated films exhibit remarkable mechanical durability, retaining TE performance under tensile strains up to 100%. Additionally, stretchable TEGs fabricated using these TE films demonstrate reliable and resilient output characteristics under mechanical deformation. This work highlights a strategy to develop high-performance and highly stretchable TE materials for self-powered wearable energy-harvesting systems.