Harness High-Temperature Thermal Energy via Elastic Thermoelectric Aerogels

Despite notable progress in thermoelectric(TE)materials and devices,developing TE aerogels with high-temperature resistance,superior TE performance and excellent elasticity to enable self-powered high-temperature monitoring/warning in industrial and wearable applications remains a great challenge.Herein,a highly elastic,flame-retardant and high-temperature-resistant TE aerogel,made of poly(3,4-ethylene dioxythiophene):poly(styrenesulfonate)/single-walled carbon nanotube(PEDOT:PSS/SWCNT)composites,has been fabricated,displaying attractive compression-induced power factor enhancement.The as-fabricated sensors with the aerogel can achieve accurately pressure stimuli detection and wide temperature range monitoring.Subsequently,a flexible TE generator is assembled,consisting of 25 aerogels connected in series,capable of delivering a maximum output power of 400μW when subjected to a temperature difference of 300 K.This demonstrates its outstanding high-temperature heat harvesting capability and promising application prospects for real-time temperature monitoring on industrial high-temperature pipelines.Moreover,the designed self-powered wearable sensing glove can realize precise wide-range temperature detection,high-temperature warning and accurate recognition of human hand gestures.The aerogel-based intelligent wearable sensing system developed for firefighters demonstrates the desired self-powered and highly sensitive high-temperature fire warning capability.Benefitting from these desirable properties,the elastic and high-temperature-resistant aerogels present various promising applications including self-powered high-temperature monitoring,industrial overheat warning,waste heat energy recycling and even wearable healthcare.

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.

Toward Enhancing Wearability and Fashion of Wearable Supercapacitor with Modified Polyurethane Artificial Leather Electrolyte

Inspired by the sophisticated artificial leather garment industry and toward enhancing wearability of energy storage devices, we demonstrate a polyurethane artificial leather supercapacitor with large sheet electrodes embedded in theleather layer simultaneously working as a polyelectrolyte. This design totally reserves textiles underneath and thus addresses the well-known challenge of wearing comfortability. It provides a revolutionary configuration of wearable supercapacitors: the artificial leather on garment is also a supercapacitor.Unlike the polyvinyl alcohol-based acidic electrolytes, which are widely used, sodium chloride is used to modify the intrinsically fluorescent polyurethane leather for ionic transportation, which has no harm to human. The fluorescent leather supercapacitor is easily transferrable from any arbitrary substrates to form various patterns, enabling multifunctionalities of practical wearability, fashion, and energy storage.

Regulating Thermogalvanic Effect and Mechanical Robustness via Redox Ions for Flexible Quasi‑Solid‑State Thermocells

The design of power supply systems for wearable applications requires both flexibility and durability.Thermoelectrochemical cells(TECs)with large Seebeck coefficient can efficiently convert lowgrade 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 quasisolid-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.

Recent advances in organic,inorganic,and hybrid thermoelectric aerogels

The thermoelectric(TE)materials and corresponding TE devices can achieve direct heat-to-electricity conversion,thus have wide applications in heat energy harvesting(power generator),wearable electronics and local cooling.In recent years,aerogel-based TE materials have received considerable attention and have made remarkable progress because of their unique structural,electrical and thermal properties.In this review,the recent progress in both organic,inorganic,and composite/hybrid TE aerogels is systematically summarized,including the main constituents,preparation method,TE performance,as well as factors affecting the TE performance and the corresponding mechanism.Moreover,two typical aerogel-based TE devices/generators are compared and analyzed in terms of assembly modes and output performance.Finally,the present challenges and some tentative suggestions for future research prospects are provided in conclusion.

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.

Flexible nanocomposite electrodes with optimized hybrid structure for improved low-grade heat harvest via thermocells

Thermal energy is ubiquitous and constantly generated in nature and society.Thermocells(TECs)represent a promising energyconversion technology that can directly translate thermal energy into electricity with a large thermopower,thus having attracted considerable attention in recent years.Nevertheless,the use of noble platinum electrodes in TECs has substantially limited their widespread applications,as the scarcity of platinum element increases the cost of materials,and its intrinsic rigidity is not conducive to flexible and wearable applications under heat sources with complex surface geometry.Herein,we propose a facile hybridizing route to constructing flexible electrodes with optimized nanostructures.The flexible composite electrode is fabricated by decorating a single-walled carbon nanotube network with conducting polypyrrole nanospheres through controlled electrochemical deposition.With refined interfacial nanostructures,the resultant composite film can facilitate carrier transport/transfer at the electrolyte-electrode interface,and thereby shows superior overall thermoelectrochemical performance to noble platinum electrode.The TEC employing the flexible composite electrodes yields a maximum output power of 2.555μW under the temperature difference of 30 K,and a device comprising 6 TEC units is assembled to efficiently utilize waste heat and human body heat,revealing the high potential of low-grade heat harvesting.

Self-healable electroluminescent devices

Electroluminescent(EL)devices have been extensively integrated into multi-functionalized electronic systems in the role of the vitally constituent light-emitting part.However,the lifetime and reliability of EL devices are often severely restricted by concomitant damage,especially when the strain exceeds the mechanical withstanding limit.We report a self-healable EL device by adopting a modified self-healable polyacrylic acid hydrogel as the electrode and a selfhealable polyurethane as a phosphor host to realize the first omni-layer-healable light-emitting device.The physicochemical properties of each functionalized layer can be efficiently restored after experiencing substantial catastrophic damage.As a result,the luminescent performance of the self-healable EL devices is well recovered with a high healing efficiency(83.2%for 10 healing cycles at unfixed spots,and 57.7%for 20 healing cycles at a fixed spot).In addition,inter-device healing has also been developed to realize a conceptual“LEGO”-like assembly process at the device level for light-emitting devices.The design and realization of the self-healable EL devices may revive their performance and expand their lifetime even after undergoing a deadly cut.Our self-healable EL devices may serve as model systems for electroluminescent applications of the recently developed ionically conductive healable hydrogels and dielectric polymers.

A Wavy-Structured Highly Stretchable Thermoelectric Generator with Stable Energy Output and Self-Rescuing Capability

Thermoelectric generators(TEGs)demonstrate great potential for flexible and wearable electronics due to the direct electrical energy harvested from waste heat.Good wearability requires high mechanical flexibility and preferable stretchability,while current TEGs are primarily developed with rigid or non-stretchable components,which do not conform well to human skin or accommodate human motions,thus hindering further applications.