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

Robust, Efficient, and Recoverable Thermocells with Zwitterion-Boosted Hydrogel Electrolytes for Energy-Autonomous and Wearable Sensing

The rapid growth of flexible quasi-solid-state thermocells (TECs) provides a fresh way forward for wearable electronics. However, their insufficient mechanical strength and power output still hinder their further applications. This work demonstrates a one-stone-two-birds strategy to synergistically enhance the mechanical and thermoelectrochemical properties of the [Fe(CN)6]3-/4--based TECs. By introducing Hofmeister effect and multiple non-covalent interactions via betaine zwitterions, the mechanical strength of the conventional brittle gelatin hydrogel electrolytes is substantially improved from 50 to 440 kPa, with a high stretchability approaching 250 %. Meanwhile, the betaine zwitterions strongly affect the solvation structure of [Fe(CN)6]3- ions, thus enlarging the entropy difference and raising the thermoelectrochemical Seebeck coefficient from 1.47 to 2.2 mV K-1. The resultant quasi-solid-state TECs exhibit a normalized output power density of 0.48 mW m-2 K-2, showing a notable improvement in overall performance compared to their counterparts without zwitterion regulation. The intrinsic thermo-reversible property also allows the TECs to repeatedly self-recover through sol-gel transformations, ensuring reliable energy output and even recycling of TECs in case of extreme mechanical damages. An energy-autonomous smart glove consisting of eighteen individual TECs is further designed, which can simultaneously monitor the temperature of different positions on any touched object, demonstrating high potential in wearable applications.

Distinguishing thermoelectric and photoelectric modes enables intelligent real-time detection of indoor electrical safety hazards

Due to the prevalence of electronic devices, intelligent sensors have attracted much interest for the detecting and providing alarms with respect to indoor electrical safety. Nonetheless, how to effectively identify various indoor electrical safety hazards remains a challenge. In this study, we fabricated single-walled carbon nanotube/poly(3-hexylthiophene-2,5-diyl) (SWCNT/P3HT) composites with exceptional bifunctional thermoelectric and photoelectric responses. Through synergy of the thermo-/photoelectric effects, the composites yielded greatly enhanced output voltages compared with the use of thermoelectric effects alone. Interestingly, modes of heat transfer can be effectively distinguished using the nominal Seebeck coefficients. Based on the remarkable output voltages and deviations in the nominal Seebeck coefficients, we developed indoor intelligent sensors capable of effectively identifying and monitoring diverse indoor electrical conditions, including electrical overheating, fire, and air conditioning flow. This pioneering investigation proposes a novel avenue for designing intelligent sensors that can recognize heat transfer modes and hence effectively monitor indoor electrical safety hazards.

Enhanced Selective Ion Transport in Highly Charged Bacterial Cellulose/Boron Nitride Composite Membranes for Thermo-Osmotic Energy Harvesting

Significant untapped energy exists within low-grade heat sources and salinity gradients. Traditional nanofluidic membranes exhibit inherent limitations, including low ion selectivity, high internal resistance, reliance on nonrenewable resources, and instability in aqueous solutions, invariably constraining their practical application. Here, an innovative composite membrane-based nanofluidic system is reported, involving the strategy of integrating tailor-modified bacterial nanofibers with boron nitride nanosheets, enabling high surface charge densities while maintaining a delicate balance between ion selectivity and permeability, ultimately facilitating effective thermo-osmotic energy harvesting. The device exhibits an impressive output power density of 10 W m-2 with artificial seawater and river water at a 50 K temperature gradient. Furthermore, it demonstrates robust power density stability under prolonged exposure to salinity gradients or even at elevated temperatures. This work opens new avenues for the development of nanofluidic systems utilizing composite materials and presents promising solutions for low-grade heat recovery and osmotic energy harvesting.

Solvation Engineering via Fluorosurfactant Additive Toward Boosted Lithium-Ion Thermoelectrochemical Cells

Lithium-ion thermoelectrochemical cell (LTEC), featuring simultaneous energy conversion and storage, has emerged as promising candidate for low-grade heat harvesting. However, relatively poor thermosensitivity and heat-to-current behavior limit the application of LTECs using LiPF6 electrolyte. Introducing additives into bulk electrolyte is a reasonable strategy to solve such problem by modifying the solvation structure of electrolyte ions. In this work, we develop a dual-salt electrolyte with fluorosurfactant (FS) additive to achieve high thermopower and durability of LTECs during the conversion of low-grade heat into electricity. The addition of FS induces a unique Li+ solvation with the aggregated double anions through a crowded electrolyte environment, resulting in an enhanced mobility kinetics of Li+ as well as boosted thermoelectrochemical performances. By coupling optimized electrolyte with graphite electrode, a high thermopower of 13.8 mV K-1 and a normalized output power density of 3.99 mW m-2 K-2 as well as an outstanding output energy density of 607.96 J m-2 can be obtained. These results demonstrate that the optimization of electrolyte by regulating solvation structure will inject new vitality into the construction of thermoelectrochemical devices with attractive properties.