Control of anisotropic conduction of carbon nanotube sheets and their use as planar-type thermoelectric conversion materials

Masamichi Matsumoto; Ryohei Yamaguchi; Keisuke Shima; Masakazu Mukaida; Motohiro Tomita; Takanobu Watanabe; Takao Ishida; Tsuyohiko Fujigaya

doi:10.1080/14686996.2021.1902243

Control of anisotropic conduction of carbon nanotube sheets and their use as planar-type thermoelectric conversion materials

Sci Technol Adv Mater. 2021 Apr 13;22(1):272-279. doi: 10.1080/14686996.2021.1902243.

Authors

Masamichi Matsumoto¹, Ryohei Yamaguchi¹, Keisuke Shima², Masakazu Mukaida³, Motohiro Tomita⁴, Takanobu Watanabe², Takao Ishida⁵, Tsuyohiko Fujigaya^{1

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Affiliations

¹ Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, Nishi-ku, Japan.
² Faculty of Science and Engineering, Waseda University, Shinjuku-ku, Japan.
³ Nanomaterials Research Institute, Department of Materials and Chemistry, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
⁴ Research Institute for Ambientornics, Waseda University, Shinjuku-ku, Japan.
⁵ Global Zero Emission Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan.
⁶ International Institute for Carbon Neutral Energy Research, Kyushu University, Nishi-ku, Japan.
⁷ Center for Molecular Systems, Kyushu University, Nishi-ku, Japan.

Abstract

The large anisotropic thermal conduction of a carbon nanotube (CNT) sheet that originates from the in-plane orientation of one-dimensional CNTs is disadvantageous for thermoelectric conversion using the Seebeck effect since the temperature gradient is difficult to maintain in the current flow direction. To control the orientation of the CNTs, polymer particles are introduced as orientation aligners upon sheet formation by vacuum filtration. The thermal conductivities in the in-plane direction decrease as the number of polymer particles in the sheet increases, while that in the through-plane direction increases. Consequently, a greater temperature gradient is observed for the anisotropy-controlled CNT sheet as compared to that detected for the CNT sheet without anisotropy control when a part of the sheet is heated, which results in a higher power density for the planar-type thermoelectric device. These findings are quite useful for the development of flexible and wearable thermoelectric batteries using CNT sheets.

Keywords: 102 Porous / Nanoporous / Nanostructured materials; 104 Carbon and related materials; 210 Thermoelectronics / Thermal transport / insulators; 50 Energy Materials; Carbon nanotubes; anisotropy; electrical conductivity; polymer particle; sacrificial template; thermal conductivity; thermoelectric conversion; wearable battery.

Grants and funding

This study was supported in part by the Nanotechnology Platform Project of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan, KAKENHI [No. JP18H01816], and the bilateral program [JPJSBP120208814] of the Japan Society for the Promotion of Science (JSPS), PRESTO [No. JPMJPR15R6], and CREST [No. JPMJCR19Q5] of the Japan Science and Technology Agency (JST), Japan.