Enhancing the thermoelectric performance of nanosized CoSb3via short-range percolation of electrically conductive WTe2 inclusions

Abstract

Compositing is proven to be effective in enhancing thermoelectric performance. The present paper illustrates the thermoelectric study of CoSb₃–yWTe₂ meso-composites between 300 K and 575 K, where y denotes the weight percentage of WTe₂ (y = 0, 3, 6, 9 and 12). Micro-sized WTe₂ grains were randomly embedded in the nano-sized unfilled CoSb₃ host matrix. We found that the electrical conductivity of CoSb₃–yWTe₂ composites was markedly increased in a systematic trend with increasing WTe₂ content. The enhancement of the electrical conductivity has been attributed to the locally percolated highly conductive WTe₂ pellets along with better electrical connections between grains as a result of increased packing density. Meanwhile, the pronounced bipolar peak of pristine CoSb₃ was quickly suppressed upon the addition of WTe₂. The n-type thermopower of CoSb₃–yWTe₂ composites became nearly linear between 300 K and 575 K, and the magnitude of thermopower decreased with increasing WTe₂ content. The power factor is markedly enhanced up to 59 times that of the pristine CoSb₃ upon compositing. The dimensionless thermoelectric figure-of-merit zT value of 0.78 is attained at 575 K, which promises practical applications for the unfilled CoSb₃ composites.