An actuatable ionogel thermoelectric fiber with aligned mesogens-induced thermopower for four-dimensional dynamically adaptive heat harvesting

Abstract

Thermoelectric (TE) ionogel have emerged as promising materials for harvesting low-grade heat owing to their flexibility and giant thermopower. However, current high-performance TE ionogel requires multi-component systems, resulting in trade-offs between TE performance, mechanics, and ion leakage risk. Moreover, the humidity-dependent thermopower and two-dimensional device architectures restrict their practical applications. Here, a thermally actuated TE ionogel fiber is designed by tailoring the interactions between liquid crystal elastomer (LCE) network and ionic liquid. Fine tuning the mesogen orientation of LCE network ensures ~3-fold thermopower boost (25.8 mV K−1) and ~30-fold electrical conductivity boom (21.5 mS m−1) at low humidity (<30% RH). Furthermore, an actuatable gripper-structured TE device can be successfully integrated, which could four-dimensional dynamically adapt to complex-geometry heat source and enable decoupled recognition of size/shapes and temperatures of the heat source. The design concepts of actuatable thermoelectrics pave ways for their commercial successes in smart wearables and soft robots. Thermoelectric ionogels are promising materials for harvesting low-grade heat, though it is difficult to balance high thermoelectric performance and mechanical properties, while high humidity environments and planar device structures limit their practical applications. Here, the authors report a thermally actuated thermoelectric ionogels by tailoring the interactions between liquid crystal elastomer networks and ionic liquids and integrate it into smart devices.