Ultralow Thermal Conductivity Achieved by All Carbon Nanocomposites for Thermoelectric Applications

• Published in: Advanced electronic materials Vol. 9; no. 7
• Main Authors: Rafique, Saqib, Burton, Matthew R., Badieh, Nafiseh, Mehraban, Shahin, Tarat, Afshin, Zuo, Guangzheng, Li, Lijie, Zhan, Yiqiang
• Format: Journal Article
• Language: English
• Published: Seoul John Wiley & Sons, Inc 01.07.2023; Wiley-VCH
• Subjects: all‐carbon; Alternative energy; Carbon; Carbon black; Conductivity; Efficiency; Electrical resistivity; few layered graphene; Fillers; Graphene; Heat conductivity; Heat transfer; Multi wall carbon nanotubes; Nanocomposites; Point defects; Power factor; Seebeck effect; Spectrum analysis; Temperature; Thermal conductivity; Thermal resistance; Thermoelectric materials; thermoelectrics; Trends; ultra‐low thermal conductivity
• ISSN: 2199-160X; 2199-160X
• DOI: 10.1002/aelm.202300023

Carbon‐based materials are becoming a promising candidate for thermoelectricity. Among them, graphene shows limited scope due to its ultra‐high thermal conductivity (κ). To develop graphene‐based thermoelectric devices, reduction of κ is highly desired while maintaining reasonably high electrical conductivity (σ). Herein, multiwalled carbon nanotubes (MWCNTs) and carbon black (CB) fillers are added into few layered graphene (FLG) to produce all‐carbon composites yielding ultra‐low thermal conductivity (κ) desired for thermoelectric applications. The novel preparation method of pristine FLG realizes very low κ of 6.90 W m−1 K−1 at 1248 K, which further reduces to 0.57, 0.81, and 0.69 W m−1 K−1 at the same temperature for FLG + MWCNTs, FLG + CB, and FLG + MWCNTs + CB, respectively. As‐prepared FLG composites also maintain reasonably high σ, whilst the Seebeck coefficient shows over a factor of five improvement after the inclusion of carbon‐based fillers. Consequently, the power factor (PF) is significantly improved. The ultralow κ is attributed to the increased thermal boundary resistance among graphene sheet boundaries. The realization of ultralow κ with simultaneous improvement in Seebeck coefficients and relatively small drops in σ with a facile and unique synthesis technique, highlight the potential of these composites. To develop light‐weight thermoelectric generators (TEGs) based on graphene, graphene's thermal conductivity needs to be substantially reduced. By developing all carbon graphene based composites with multiwalled carbon nanotubes (MWCNTs) and carbon black (CB), the thermal conductivity is reduced substantially, whilst simultaneously improving the power factor of the material through Seebeck coefficient enhancement.