Enhanced thermoelectric performance and mechanical strength in GeTe enable power generation and cooling

Finding a real thermoelectric(TE)material that excels in various aspects of TE performance,mechanical properties,TE power generation,and cooling is challenging for its commercialization.Herein,we report a novel multifunctional Ge0.78Cd0.06Pb0.1Sb0.06Te material with excellent TE performance and mechanical strength,which is utilized to construct candidate TE power generation and cooling devices near room temperature.Specifically,the effectiveness of band convergence,combined with optimized carrier concentration and electronic quality factor,distinctly boosts the Seebeck coefficient,thus greatly improving the power factor.Advanced electron microscopy observation indicates that complex multi-scale hierarchical structures and strain field distributions lead to ultra-low lattice thermal conductivity,and also effectively enhance mechanical properties.High ZT0.6 at 303 K,average ZTave1.18 from 303 to 553 K,and Vickers hardness of200 Hv in Ge0.78Cd0.06Pb0.1Sb0.06Te are obtained synchronously.Particularly,a 7-pair TE cooling device with a maximumΔT of45.9 K at Th=328 K,and a conversion efficiency of5.2%at Th=553 K is achieved in a single-leg device.The present findings demonstrate a unique approach to developing superior multifunctional GeTe-based alloys,opening up a promising avenue for commercial applications.

Annealing engineering induced high thermoelectric performance in Yb-filled CoSb_(3) skutterudites

The great pressure of energy shortage has made CoSb_(3) materials with excellent mechanical stability in the mid-temperature region favored for the integration of thermoelectric devices.However,their ex-cessive lattice thermal conductivity and poor Seebeck coefficient lead to low energy conversion effi-ciency.Filling Yb into the lattice void to optimize the band structure and regulate the chemical po-tential is an indispensable means for improving the thermoelectric properties of CoSb_(3)-based materials,while the phase structure and thermoelectric properties vary with the preparation process.This motivates the current work to focus on the influence of annealing temperature on the microstructure and thermoelectric properties of Yb-filled CoSb_(3).Experimental analysis and theoretical model eluci-dated that an increase in annealing temperature can optimize the Yb filling fraction,which simulta-neously manipulates the band structure as well as chemical potential,resulting in an excellent electrical property.Furthermore,the phase and microstructure characterization clarify that the annealing temperature can effectively affect the grain size.The complex grain boundary induced by grain refinement,more filled Yb atoms and precipitates strongly scatter wide-frequency phonons,significantly suppressing the lattice thermal conductivity.As a result,a superior dimensionless figure of merit(ZT)value of~1.33 at 823 K and an average ZTave of~0.9(323-823 K)were achieved in the Ybo.4Co4Sb12 sample annealed at 923 K,and the calculated conversion efficiency could reach~13%.This work pro-vides a unique paradigm to improve thermoelectrics in the filled CoSb_(3)-based skutterudites by annealing engineering.

Research progress of p-type Fe-based skutterudite thermoelectric materials

Filled skutterudite is currently one of the most promising intermediate-temperature thermoelectric(TE)materials,having good thermoelectric transport performance and excellent mechanical properties.For the preparation of high-efficiency filled skutterudite TE devices,it is important to have p-and n-type filled skutterudite TE materials with matching performance.However,the current TE properties of p-type Fe-based filled skutterudite materials are worse than n-type filled skutterudite materials.Therefore,how to obtain high-performance p-type Fe-based filled skutterudite materials is the key to preparation of high-efficiency skutterudite-based TE devices.This review summarizes some methods for optimizing the thermal transport performance of p-type filled skutterudite materials at the atomic-molecular and nano-mesoscopic scale that have been used in recent years.These methods include doping,multi-atom filling,and use of low-dimensional structure and of nanocomposite.In addition,the synergistic optimization methods of the electrical and thermal transport parameters and advanced preparation technologies of p-type filled skutterudite materials in recent years are also briefly summarized.These optimizational methods and advanced preparation technologies can significantly improve the TE properties of p-type Fe-based filled skutterudite materials.