Search

Abstract The design of power supply systems for wearable applications requires both flexibility and durability. Thermoelectrochemical cells (TECs) with large Seebeck coefficient can efficiently convert low-grade heat into electricity, thus having attracted considerable attention in recent years. Utilizing hydrogel electrolyte essentially addresses the electrolyte leakage and complicated packaging issues existing in conventional liquid-based TECs, which well satisfies the need for flexibility. Whereas, the concern of mechanical robustness to ensure stable energy output remains yet to be addressed. Herein, a flexible quasi-solid-state TEC is proposed based on the rational design of a hydrogel electrolyte, of which the thermogalvanic effect and mechanical robustness are simultaneously regulated via the multivalent ions of a redox couple. The introduced redox ions not only endow the hydrogel with excellent heat-to-electricity conversion capability, but also act as ionic crosslinks to afford a dual-crosslinked structure, resulting in reversible bonds for effective energy dissipation. The optimized TEC exhibits a high Seebeck coefficient of 1.43 mV K−1 and a significantly improved fracture toughness of 3555 J m−2, thereby can maintain a stable thermoelectrochemical performance against various harsh mechanical stimuli. This study reveals the high potential of the quasi-solid-state TEC as a flexible and durable energy supply system for wearable applications.

Abstract Solution processability and flexibility still remain major challenges for many thermoelectric (TE) materials, including bismuth telluride (Bi2Te3), a typical and commercially available TE material. Here, we report a new solution‐processed method to prepare a flexible film of a Bi2Te3/single‐walled carbon nanotube (SWCNT) hybrid, where the dissolved Bi2Te3 ion precursors are mixed with dispersed SWCNTs in solution and recrystallized on the SWCNT surfaces to form a “cement–rebar”‐like architecture. The hybrid film shows an n‐type characteristic, with a stable Seebeck coefficient of −100.00 ± 1.69 μV K−1 in air. Furthermore, an extremely low in‐plane thermal conductivity of ∼0.33 W m−1 K−1 is achieved at 300 K, and the figure of merit (ZT) reaches 0.47 ± 0.02. In addition, the TE performance is independent of mechanical bending. The unique “cement–rebar”‐like architecture is believed to be responsible for the excellent TE performances and the high flexibility. The results provide a new avenue for the fabrication of solution‐processable and flexible TE hybrid films and will speed up the applications of flexible electronics and energy conversion.

Abstract Polymer thermoelectric (TE) composites have witnessed explosive developments in recent years, arising from their promising prospect for lightweight flexible electronics and capability of harvesting waste-heat. In sharp contrast with intrinsically conducting polymers (CPs), the insulating thermoplastics have seldom been employed as the matrices for flexible TE composites despite their advantages of low costs, controllable melt-flowing behaviors and excellent mechanical properties. Here, we report flexible films of polycarbonate/single-walled carbon nanotube (PC/SWCNT) composites with improved trade-off between TE and mechanical performances. The SWCNTs with 1D nanostructure were dramatically aligned by PC melt-flowing under hot-pressing in the radial direction. The composite maximum power factor reaches 4.8 ± 0.8 μW m−1 K−2 at 10 wt% SWCNTs in the aligned direction, which is higher than most previously reported thermoplastics-based TE composites at the same SWCNT loading and even comparable to some intrinsically CPs and their composites. In addition, these composites display significantly higher tensile modulus and strength than CPs and their composites. This study paves an effective way to fabricate flexible films of polymer composites with simultaneously high TE and mechanical performances via judicious alignment of SWCNTs in thermoplastic polymers.