Durable and stretchable nanocomposite ionogels with high thermoelectric property for low-grade heat harvesting

Stretchable ionic thermoelectric(i-TE) materials have attracted growing interest in converting low-grade thermal energy into electricity. However, substantial improvement on i-TE performance of quasi-solid ionogels remains a significant challenge.Here, a nanocomposite ionogel with skin-like stretchability, high i-TE performance, thermostability and durability is prepared by hybridizing ionic liquid(IL) and Laponite nanosheets into waterborne polyurethane(WPU). With multiple H-bond, WPU can accommodate a higher content of IL, thereby improving its ionic conductivity. After cation exchange between IL and Laponite,the negatively charged Laponite sheets and released Na+can enhance the ionic Seebeck coefficient by enlarging thermophoretic mobility difference between the cations and anions in ionogel. Besides, incorporation of Laponite causes the decrease of thermal conductivity. Thus, the WPU-IL-Laponite ionogel exhibits a high ionic thermopower of 44.1 m V K-1, high ionic conductivity of 14.1 m S cm-1and low thermal conductivity of 0.43 W m-1K-1at a relative humidity of 90%. The corresponding ionic figure of merit of the ionogel is 1.90±0.27. Moreover, the ionogel demonstrates excellent durability during repeated stretching process.The stretchable ionogel can be fabricated into ionic thermoelectric capacitor to convert thermal energy from solar radiation into electricity.

Facile Fabrication of Cotton‑Based Thermoelectric Yarns for the Construction of Textile Generator with High Performance in Human Heat Harvesting

Thermoelectric(TE)textiles which can harvest thermal energy from the human body,are highly desirable and vital to the charging of wearable electronics owing to their stable and long-term power output.The typical carbon nanotube(CNT)yarns or bismuth telluride(Bi2Te3)based inorganic TE materials used hitherto limit the development of TE textiles,because of their high cost and rareness.In this work,scalable and high-TE performance carbon nanotube composite yarns(CNTYs)are developed using p-and n-type tuneable multi-wall CNTs and single-wall CNTs as TE materials and waterborne polyurethane(WPU)as the binder.The mechanical properties of the CNTYs are tuned and improved considerably by adding a small amount of WPU.Furthermore,TE yarns with p-and n-type segmented structures are prepared by treating CNTYs with poly(3,4-ethylene dioxythiophene):polystyrene sulfonate solution and n-type dopant polyetherimide,respectively.Based on the prepared p-and n-type segmented TE yarns,a TE textile with 75 p-n pairs that achieve outstanding TE output is fabricated.The TE textile can generate a high power density of 95.74μW m^(−2)with a voltage density of 3.76 V m^(−2)at a temperature difference of 32 K.It provides an output voltage of~37 mV outdoors(~12℃)when worn on the arm and demonstrates potential application to electronic devices after amplification.The fabrication method used in this study is not only a low-cost,scalable for preparing high-performance TE yarns but also realizes the body heat harvesting and temperature sensing of yarn-based TE textiles.

Swift Assembly of Adaptive Thermocell Arrays for Device‑Level Healable and Energy‑Autonomous Motion Sensors

The evolution of wearable technology has prompted the need for adaptive,self-healable,and energy-autonomous energy devices.This study innovatively addresses this challenge by introducing an MXene-boosted hydrogel electrolyte,which expedites the assembly process of flexible thermocell(TEC)arrays and thus circumvents the complicated fabrication of typical wearable electronics.Our findings underscore the hydrogel electrolyte’s superior thermoelectrochemical performance under substantial deformations and repeated self-healing cycles.The resulting hydrogel-based TEC yields a maximum power output of 1032.1 nW under theΔT of 20 K when being stretched to 500%for 1000 cycles,corresponding to 80%of its initial state;meanwhile,it sustains 1179.1 nW under theΔT of 20 K even after 60 cuthealing cycles,approximately 92%of its initial state.The as-assembled TEC array exhibits device-level self-healing capability and high adaptability to human body.It is readily applied for touch-based encrypted communication where distinct voltage signals can be converted into alphabet letters;it is also employed as a self-powered sensor to in-situ monitor a variety of body motions for complex human actions.The swift assembly approach,combined with the versatile functionality of the TEC device,paves the way for future advancements in wearable electronics targeting at fitness monitoring and human–machine interfaces.

Self-assembled aerogel sheet electrodes of thermocells for low-grade heat harvest

Efficiently harvesting low-grade heat is crucial for sustainable energy management. Thermocells(TECs), inducing heat-toelectricity conversion via the thermogalvanic effect, have thus drawn tremendous attention in recent years. This study introduces a self-assembly approach for fabricating aerogel sheet electrodes(ASEs) tailored for TECs. The crafted ASEs retain a remarkable porous architecture with approximately 95% porosity, even with their slimmed-down thickness. Results reveal that the electrode composition has minimal influence on the thermopower of TECs. Notably, the porous ASE with tunned composition demonstrates an optimal effective surface area for the thermogalvanic effect, resulting in enhanced output current density. This balances the desirable traits of electrode compactness with abundant redox active sites, positioning it favorably against conventional bulky electrode designs. The TECs utilizing the optimized ASE achieve a peak output power of 22.10 μW cm^(-2)under a temperature difference of 30 K. Furthermore, a tubular TEC device is readily assembled and specially designed for harvesting heat energy from hot fluids. These findings underscore the potential of composite electrodes in the realm of low-grade heat harvest, paving the way for broader applications in sustainable energy solutions.

Charging-free thermally regenerative electrochemical cycle for electricity generation from daytime solar heat and nighttime darkness

The extensive exploration of energy conversion harvested from the environment into electricity is recently driven by the significant demand to power off-grid electronics,particularly Internet-of-Things(IoT)sensors.This highlight previews the latest advance of a charging-free thermally regenerative electrochemical cycle(TREC)for continuous electricity generation from solar heat and darkness with the aid of dual-mode thermal regulations.Such a spontaneous all-day electricity generation with high power and efficiency shows great potential for powering a wide range of distributed electronics for IoT and other applications.