Scalable-produced 3D elastic thermoelectric network for body heat harvesting

Abstract

Flexible thermoelectric generators can power wearable electronics by harvesting body heat. However, existing thermoelectric materials rarely realize high flexibility and output properties simultaneously. Here we present a facile, cost-effective, and scalable two-step impregnation method for fabricating a three-dimensional thermoelectric network with excellent elasticity and superior thermoelectric performance. The reticular construction endows this material with ultra-light weight (0.28 g cm−3), ultra-low thermal conductivity (0.04 W m−1 K−1), moderate softness (0.03 MPa), and high elongation (>100%). The obtained network-based flexible thermoelectric generator achieves a pretty high output power of 4 μW cm−2, even comparable to state-of-the-art bulk-based flexible thermoelectric generators.

Weavable thermoelectrics: advances, controversies, and future developments

“…With the advancement of thermoelectric science and technology, the morphology of weavable thermoelectric materials has become diverse, and the research focus in this field continues to evolve. Generally, research focus areas in weavable thermoelectrics can be categorized as indicated by figure 2, including 1D fibers [42,43, and nanowires (NWs) [167,168], 2D thin films [169][170][171][172], 3D fabrics [173][174][175][176][177][178][179][180][181][182][183][184][185][186], device assembling [42,43,124], simulations [187,188], and integrations [189]. Among them, thermoelectric fibers with typical 1D macroscopic morphologies have garnered significant research attention.…”

“…Another research emphasis includes the design of substrates or supports that match woven thermoelectric fibers, such as common fabrics, flexible strings, and silicone. These support materials can serve solely as structural supports [173][174][175] or be thermoelectrically functionalized [176][177][178][179][180][181][182][183][184][185][186].…”

“…Fabrics used as flexible substrates can also be functionalized, especially for thermoelectric purposes, to further enhance the overall performance of W-TEDs. For example, common design approaches include modifying traditional wool or synthetic fabrics and depositing thermoelectric layers onto them using solution-based or deposition methods [176][177][178][179][180][181][182][183][184][185][186]. Additionally, some research explores the direct use of thermoelectric fabrics as 3D thermoelectric legs, functioning similarly to 1D weavable thermoelectric fibers.…”

“…The fabrics can serve as substrate or template materials for depositing thermoelectric materials as coatings. For the case of direct use of thermoelectric fabrics as 3D thermoelectric legs, figure 10(a) illustrates filled, 10% filled bulk devices, and a network-based flexible device, respectively [181]. Compared with conventional devices with bulk materials, the ones with fabric networks can exhibit both excellent elasticity and good thermoelectric performance.…”

“…Compared with conventional devices with bulk materials, the ones with fabric networks can exhibit both excellent elasticity and good thermoelectric performance. To achieve this goal, figure 10(b) illustrates the composition of the Ag 2 Se network, which is in-situ synthesized by silvering and then selenizing [181]. Figure 10(c) is the photo of a large-scale Ag 2 Se network.…”