Preparation And Performance Tuning Of Bi₂S₃-based Composite Thermoelectric Materials

Thermoelectric materials can realize the mutual conversion of electric energy and thermal energy and have a wide range of applications in waste heat power generation and semiconductor refrigeration.The Bi2S3 base thermoelectric material studied in this paper is anew type of thermoelectric material.Compared with the traditional commercial bismuth telluride base and lead telluride base thermoelectric material,it has the advantages of abundant constituent elements,low price and low toxicity.However,due to the low conductivity,its thermoelectric performance can't be up to the standard of replacing the traditional high-performance thermoelectric materials.Therefore,based on N-type bismuth sulfide thermoelectric materials,this paper adopts mechanical alloy method,hydrothermal synthesis method,ionic liquid method to prepare powders and discharge plasma sintering method to prepare polycrystalline block.By preparing silver telluride nanowire/bismuth sulfide composite block material and Ni composite bismuth sulfide block material,this paper has investigated the influence of different second phase relative bismuth sulfide's thermoelectric properties.The performances of bismuth sulfide thermoelectric material has also been optimizedExperimental results show the composition of a small number of silver telluride nanowires can improve the carrier concentration and mobility of bismuth sulfide.Thus,improving its thermoelectric performance.The maximum ZT value of bismuth sulfide block with 1 wt%silver telluride nanowire at 623 K is 0.12,which is nearly twice higher than that of the pure bismuth sulfide block.On the other hand,mental Ni composite bismuth sulfide thermoelectric materials were prepared by ionic liquid method.By introducing AgBi3S5 second phase and Ni elements,the carrier concentration and mobility of bismuth sulfide were optimized.This not only enhanced the conductivity of bismuth sulfide but also prevented the Seebeck coefficient from being greatly reduced.At the same time,the introduction of second phase also increases the scattering of long-wave phonons and reduces the thermal conductivity of bismuth sulfide.Finally,the optimal ZT value of Ni composite bismuth sulfide is 0.38 at 628 K,which is nearly 6 times higher than that of the pure phase bismuth sulfide.