Effect of Poly(Vinyl Alcohol) on Thermoelectric Properties of Sodium Cobalt Oxide

Abstract

Organic polymer composites are relatively simple to process and are therefore used in thermoelectric materials. The organic polymers are used as an adhesive agent between thermoelectric material grains. Thermoelectric effects of poly (vinyl alcohol) (PVA) composited with sodium cobalt oxide (NaxCoO2) were studied in this work. PVA is a low cost and an excellent biocompatibility polymer. High electrical conductivity, high Seebeck coefficient and low thermal conductivity are required in thermoelectric materials. As PVA is an insulating material, the PVA in between NaxCoO2 grain boundaries has an effect on the low electrical conductivity of NaxCoO2 composite. This results in a decrease in thermoelectric efficiency. However, PVA has been utilized to increase the Seebeck coefficient and also enhance thermoelectric efficiency. In order to improve the electrical conductivity of NaxCoO2 composite, PVA removal was produced by furnace heating at 500̊ C to eliminate PVA from NaxCoO2/PVA sample. The general thermoelectric parameters including the Seebeck coefficient, electrical conductivity and power factor of NaxCoO2/PVA and PVA removal sample were compared. X-ray diffraction patterns (XRD) and scanning electron microscope (SEM) images were used to identify the phase identification and morphology study, respectively. The results showed that the PVA removal sample had higher electrical conductivity than the NaxCoO2/PVA sample. However, NaxCoO2/PVA sample had higher thermoelectric performance than the PVA removal sample because the NaxCoO2/PVA sample showed higher Seebeck coefficient and power factor.

Flexible N-Type Thermoelectric Composites Based on Non-Conductive Polymer with Innovative Bi2Se3-CNT Hybrid Nanostructured Filler

“…Presumably, this effect could be attributed to the influence of PVOH on the existing thermoelectric properties of material. Previously, the same effect of the increase of Seebeck coefficient by ~30% was reported for graphene and sodium cobalt oxide nanoparticles after their introduction into the PVOH matrix [ 30 , 31 ]. However, the mechanism of the increase of Seebeck coefficient upon introduction of the material into PVOH is not clarified yet.…”

p-Type PVA/MWCNT-Sb2Te3 Composites for Application in Different Types of Flexible Thermoelectric Generators in Combination with n-Type PVA/MWCNT-Bi2Se3 Composites

“…Thus, the PVA-based thermoelectric composites are suitable candidates for indoors applications related to low-grade heat conversion (for example, the conversion of human body heat or hot pipes). In addition, some previous reports showed that the application of PVA as a binder for thermoelectric nanomaterials may noticeably enhance their Seebeck coefficient [ 12 , 13 ]. The main reported drawback of the use of PVA as a matrix for thermoelectric composites is the very high electrical resistivity of the neat PVA, and consequently, the output power of the resulting thermoelectric composites, which are significantly lower in comparison with the electrically conductive polymers-based counterparts.…”

Determination of Lorenz number of composite films based on copper chloride(II) in polyvinyl alcohol matrix

“…This result may be due to compactness provided by increase in dopants concentration which increase the heat transfer through phonons diffusion. 18 The Lorenz number is a thermoelectrical parameter characterising the effect of temperature on both the thermal and electrical conductivities of a solid material. Knowledge of the Lorenz number is important in the design of the thermoelectric materials and in the experimental determination of the lattice thermal conductivity.…”

“…This result may be due to compactness provided by increase in dopants concentration which increase the heat transfer through phonons diffusion. 18…”