3D spacer fabrics for thermoelectric textile cooling and energy generation based on aluminum doped zinc oxide

Abstract

It is demonstrated that spacer fabrics made of polyester can be coated with Al-doped ZnO (AZO) as thermoelectric (TE) material and conductive silver as contact material to enable smart textiles. An atomic layer deposition process was used for the AZO coating and the conductive silver paste was manually applied. A TE generator and cooling based on the Seebeck and Peltier effect can be observed if a temperature difference or direct current is applied, respectively. Both effects were proven to exist and evaluated. The Seebeck coefficient was determined of up to 50 µV · K−1 and a TE power of about 0.2 µW was generated. Without additional active heat dissipation or cooling, a temperature difference between both spacer fabric surfaces of up to 12 K was achieved. By changing the polarity of the electrical contacts it can significantly be shown that the cold-warm side is changed, as expected for a Peltier element. We observed experimentally the Peltier effect using a single element as well as electrically interconnected sample pairs, the latter could be important for the cooling application. Additionally, the heat transport through the spacer fabrics was tested and showed that there is no heat equalization between the surfaces via air and filaments at temperatures up to 50 °C. The Peltier effect as a fundamental TE effect, that enables site-specific and on-demand cooling applications, has not yet been comprehensively investigated using spacer fabrics and AZO as TE material. These investigations predict that AZO on spacer fabrics hold the special potential to enable flexible and textile solid-state cooling applications.

Multifunctional Wearable Thermoelectrics for Personal Thermal Management

“…After proper flexibility design, bulk-based thermoelectric PTM can realize a power output of around 100 µW, [32,114,116] the thin film-based thermoelectric PTM can generally generate the power output of about 10 µW, [119,122,123] and the fiber-based PTM can realize a power output of around 5 µW through harvesting human body waste heat. [7,128,134] These wearable thermoelectric PTM can provide reliable and continuous power-supply for electronics by integrating with voltage step-up converter and other elements. Although, the performance of thin film-and fiber-based thermoelectric PTM are much lower than bulk-based counterparts, the higher flexibility has delivered them extensive potential for wide applications.…”

“…[134] The wearable 3D fiber-based TED can generate the power output of 0.2 µW at the ΔT of 68 K, which realizes the ΔT (between the hot side and cold side of the wearable TED) of ≈12 K under the I of ≈300 mA, as shown in Figure 11e. [134] Sun et al [7] designed a wearable 3D fiber-based TED without substrate by directly knitting the p-type carbon nanotube fibers (CNTF)/PEDOT:PSS and n-type CNTF/oleamine composite thermoelectric materials into the textiles. The observed output power density of the designed fiber-based TED can approach as high as 70 mW m −2 under a ΔT of 44 K. [7] Xu et al [127] designed a wearable fiber-based TED by utilizing PEDOT:PSS/Te nanowires composite fibers at the commercial fabrics.…”

“…[126] Schmidl et al [134] also proposed a wearable 3D fiber-based TED by coating polyester with Al-doped ZnO as thermoelectric material and conductive silver as contact material. [134] The wearable 3D fiber-based TED can generate the power output of 0.2 µW at the ΔT of 68 K, which realizes the ΔT (between the hot side and cold side of the wearable TED) of ≈12 K under the I of ≈300 mA, as shown in Figure 11e. [134] Sun et al [7] designed a wearable 3D fiber-based TED without substrate by directly knitting the p-type carbon nanotube fibers (CNTF)/PEDOT:PSS and n-type CNTF/oleamine composite thermoelectric materials into the textiles.…”

“…[ 126 ] The as‐designed fiber‐based TED shows high stability as demonstrated by the minor change of normalized resistance as a function of bending radius (the inset of Figure 11d). [ 126 ] Schmidl et al [ 134 ] also proposed a wearable 3D fiber‐based TED by coating polyester with Al‐doped ZnO as thermoelectric material and conductive silver as contact material. [ 134 ] The wearable 3D fiber‐based TED can generate the power output of 0.2 µW at the ΔT of 68 K, which realizes the Δ T (between the hot side and cold side of the wearable TED) of ≈12 K under the I of ≈300 mA, as shown in Figure 11e.…”

“…e) Δ T between the top and bottom space fabric as a function of the current ( I ). [ 134 ] Reproduced with permission. [ 134 ] Copyright 2020, IOP publishing.…”