Research On Preparation And Properties Of Bi-Te Based Alloy/Single-Walled Carbon Nanotube/Polymer Composite Thermoelectric Materials

Thermoelectric material is a kind of function material which can convert waste heat into electrical energy through carrier transporting.Bi₂Te₃ has an excellent thermoelectric property near room temperature.Single-walled carbon nanotube(SWCNT),which has extraordinary electrical property,is often used as the second phase to prepare composite functional materials.Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)has many advantages,such as good flexibility,high electrical conductivity,and relatively low thermal conductivity.PEDOT:PSS has a great potential for the applications in the thermoelectric field.Herein,the above-mentioned three materials was used for preparation of the corresponding composite thermoelectric materials.The main research content is as below:(1)The SWCNT/Bi₂Te₃ composite powder was prepared by a hydrothermal method,and the SWCNT/Bi₂Te₃ composite bulk material was prepared by the cold pressing combining pressureless sintering process.The SWCNT/Bi₂Te₃ composite bulk with a SWCNT content of0.5 wt.%prepared by the cold-pressing method has a power factor of 38.6?Wm^-1K^-2 at room temperature.When the pressureless sintering temperature rises from 598 K to 698 K,the conductivity of SWCNT/Bi₂Te₃ composite bulk increases,while the|S|decreases,and a highest power factor of 168?Wm^-1K^-2 is obtained for the SWCNT/Bi₂Te₃ composite bulk pressureless sintered at 698 K for 1 h.(2)The SWCNT/Bi₂Te₃ composite bulk material was prepared by a hot-pressing sintering method.When the test temperature rises from 300 K to 360 K,the electrical conductivity of the SWCNT/Bi₂Te₃ composite bulk shows a decreasing trend from 782.6 S/cm to 736.4 S/cm.The absolute value of the Seebeck coefficient of the composite bulks first increases and then decreases.The absolute value of the Seebeck coefficient of the SWCNT/Bi₂Te₃ composite bulk is 109.2?V/K at 340 K.The maximum power factor of the composite bulk prepared by a hot-pressing progress is 891.6?Wm^-1K^-2at 340 K.(3)The SWCNT/Bi₂Te₃/MC flexible composite films were fabricated a screen printing progress.And then the cold-pressing combining with pressureless sintering treatment has been used for the as-prepared films.With the contents of SWCNT/Bi₂Te₃rises from 60 wt.%to 80wt.%,the conductivity of SWCNT/Bi₂Te₃/MC composite films first increases and then decreases,and the absolute value of the Seebeck coefficient of the SWCNT/Bi₂Te₃ composite bulk increases.After cold-pressing,a highest power factor of 0.20?Wm^-1K^-2 is achieved at 360K for the SWCNT/Bi₂Te₃/MC composite film with 70 wt.%of SWCNT/Bi₂Te₃.A power factor of 5.31?Wm^-1K^-2 at 360 K is achieved for the SWCNT/Bi₂Te₃/MC composite film containing70 wt.%SWCNT/Bi₂Te₃ after the cold-pressing combining with pressureless sintering treatment.(4)The SWCNT/Bi₂Se_0.3Te_2.7/MC composite film was prepared by a screen printing process.The microstructure of SWCNT/Bi₂Se_0.3Te_2.7/MC composite film containing 95.2 wt.%Bi₂Se_0.3Te_2.7 was characterized,and its thermoelectric properties were tested.SWCNT/Bi₂Te₃/MC/PEDOT:PSS composite films were prepared on the basis of the SWCNT/Bi₂Te₃/MC flexible composite thermoelectric film after being cold-pressing combined with pressureless sintering by the screen printing process(the content of SWCNT/Bi₂Te₃ in this ternary composite film is 70 wt.%).And then the DMSO treatment was carried on the SWCNT/Bi₂Te₃/MC/PEDOT:PSS composite film.A power factor of 6.36?Wm^-1K^-2 at 360 K is obtained for SWCNT/Bi₂Te₃/MC/PEDOT:PSS composite film.After DMSO treatment,the conductivity of SWCNT/Bi₂Te₃/MC/PEDOT:PSS composite film increased at 300 K,and the|S|increased slightly.A maximum power factor of 11.96?Wm^-1K^-2at 360 K?Wm^-1K^-2 is obtained for the SWCNT/Bi₂Te₃/MC/PEDOT:PSS composite film after DMSO treatment.