Figure 1. (a) An illustration of the forming process of the GB-HCF hydrogel. (b) An SEM image of the GB-HCF and the corresponding elemental mapping images. (c) FTIR spectra of various samples. (d) Raman spectra of various samples. (e) XPS full spectra of various samples. (f) XPS C1s spectra of various samples. (g) XPS Fe2p spectrum of the GB-HCF.
Figure 2. (a) Stress-strain curves of various samples. (b) The corresponding tensile strength and elongation at break of various samples obtained from (a). (c) Demonstration of the GB[1]HCF hydrogel lifting a weight of 2.5 kg. The schematic diagram highlights the role of betaine in the hydrogel network, where the betaine molecules can bind the gelatin chains tightly through multiple non-covalent interactions including hydrogen bonds and electrostatic interactions. (d) Compression curves of various samples. (e) The corresponding compressive strength of various samples obtained from (d). (f) Stress-strain curves of cyclic compression of the GB-HCF. (g) Demonstration of the tailorable GB-HCF hydrogels and their healing capability. (h) Stress[1]strain curves of the GB-HCF before and after healing. (i) Stress-strain curves of the GB-HCF subjected to five recovery cycles. Insets show its self-recovery process based on the sol-gel transformation.
Figure 3. (a) UV-vis spectra of the [Fe(CN)6]4− and [Fe(CN)6]4− + betaine sample. (b) UV-vis spectra of the [Fe(CN)6]3− and [Fe(CN)6]3− + betaine sample. (c) XPS N 1s spectra of various samples. (d) The calculated binding energies for [Fe(CN)6]4-betaine and [Fe(CN)6]3−-betaine. Insets show the optimized binding structures. (e) The radial density profiles between [Fe(CN)6]3−/[Fe(CN)6]4− and water/betaine molecules. (f) The illustration of the solvation structures of [Fe(CN)6]3− and [Fe(CN)6]4− with the presence of betaine.
Figure 4. (a) The effect of betaine concentration on the Se. (b) The effect of betaine concentration on the ionic conductivity. (c) The Se change during the rest in air for 7 days. (d)The fitted plots of voltage-temperature difference for different recovery cycles. (e) The measured Se values after different recovery cycles. Insets show the recovery cycle. (f) Current density-voltage plots under different ∆Ts. (g) Power density-voltage plots under different ∆Ts. (h) The calculated maximum specific output power density. (i) Comprehensive comparisons between the GB-HCF based TECs and conventional gelatin-based TECs in terms of Pmax/∆T2, Se, σ, tensile strength, and stretchability.
Figure 5. (a) An optical image of the smart glove consisting of 18 TEC blocks. (b) Schematic of the configuration of a single TEC block. (c) Photos showing a TEC block powering a light[1]emitting diode bulb by utilizing the body heat with the assistance of a voltage amplifier. (d) Corresponding infrared thermal images. (e) A schematic of the hand-shaped smart glove. (f)Demonstration of wearing the smart glove device to hold different objects. The schematics in the lower part show the voltage responses in different zones of the hand. (g) The variation of ∆U/U0 values with the variation of the target temperature. (h) The relationship between the ∆U/U0 values and the target temperature. (i-l) The voltage responses of the device when the hand was touching a pentagram toy, a duck toy, a cylinder, and a cold/hot water cup. Insets are the photos showing how the hand was holding the objects.
总结与展望
总之，作者报告了一种“一石二鸟”的策略，即同时增强 TEC 的机械性能和热电化学性能并深入探讨了其作为可穿戴传感器的应用。这种有效的策略是通过使用增效的 GB-HCF 水凝胶电解质来实现的，其中甜菜碱齐聚物丰富的-N+(CH3)3 阳离子和 -COO-阴离子基团可以通过非共价作用与明胶链紧密结合，从而改善机械性能。同时， 甜菜碱分子与[Fe(CN)6]3-离子之间的优先结合导致后者的溶壳重新排列，从而扩大了熵差，增加了Se。 因此， 所获得的基于GB-HCF的 TEC 的拉伸强度显著提高，达到 440 kPa，Se值达到2.2 mVK-1，归一化输出功率密度高达0.48mWm-2K-2。这些特性大大超过了基于传统明胶电解质的 TEC 。此外，由于明胶基电解质的热可逆性，TECS可以通过溶胶-凝胶转化实现反复的自我恢复循环，从而提高了 TECs 在极端机械损伤下的实用性。作者设计了一种集成了TEC 阵列的自供电智能手套，可实时监测任何被触摸物体不同位置的温度，证明了基于 GB-HCF 的 TEC 在能量自主可穿戴传感应用中的能力。
文献链接
Robust, Efficient, and Recoverable Thermocells with Zwitterion-Boosted Hydrogel Electrolytes for Energy-Autonomous and Wearable Sensing
https://doi.org/10.1002/anie.202405357