RESUMEN
Currently, the only thermoelectric (TE) materials commercially available at room temperature are those based on bismuth telluride. However, their widespread application is limited due to their inferior thermoelectric and mechanical properties. In this study, a strategy of growing a rigid second phase of MoSe2 is employed, in situ within the matrix phase to achieve n-type bismuth telluride-based materials with exceptional mechanical and thermoelectric properties. The in situ grown second phase contributes to both the electronic and lattice thermal conductivities. This is primarily attributed to the strong energy filtering effect, as the second phase forms a semi-common lattice interfacial structure with the matrix phase during growth. Furthermore, for composites containing 2 wt% MoSe2, a maximum zT value of 1.24 at 373 K can be achieved. On this basis, 8-pair TE module is fabricated and 1-pair TE module is optimized using a homemade p-type material. The optimized 1-pair TE module generates a maximum output power of 13.6 µW, which is twice that of the 8-pair TE module and four times more than the 8-pair TE module fabricated by commercial material. This work facilitates the development of the TE module by presenting a novel approach to obtaining bismuth telluride-based thermoelectric materials with superior thermoelectric and mechanical properties.
RESUMEN
Thermoelectric modules can convert waste heat directly into useful electricity, providing a clean and sustainable way to use fossil energy more efficiently. Mg3Sb2-based alloys have recently attracted considerable interest from the thermoelectric community due to their nontoxic nature, abundance of constituent elements and excellent mechanical and thermoelectric properties. However, robust modules based on Mg3Sb2 have progressed less rapidly. Here, we develop multiple-pair thermoelectric modules consisting of both n-type and p-type Mg3Sb2-based alloys. Thermoelectric legs based on the same parent fit into each other in terms of thermomechanical properties, facilitating module fabrication and ensuring low thermal stress. By adopting a suitable diffusion barrier layer and developing a new joining technique, an integrated all-Mg3Sb2-based module demonstrates a high efficiency of 7.5% at a temperature difference of 380 K, exceeding the state-of-the-art same-parent thermoelectric modules. Moreover, the efficiency remains stable during 150 thermal cycling shocks (â¼225 h), demonstrating excellent module reliability.
RESUMEN
As the sole dominator of the commercial thermoelectric (TE) market, Bi2 Te3 -based alloys play an irreplaceable role in Peltier cooling and low-grade waste heat recovery. Herein, to improve the relative low TE efficiency determined by the figure of merit ZT, an effective approach is reported for improving the TE performance of p-type (Bi,Sb)2 Te3 by incorporating Ag8 GeTe6 and Se. Specifically, the diffused Ag and Ge atoms into the matrix conduce to optimized carrier concentration and enlarge the density-of-states effective mass while the Sb-rich nanoprecipitates generate coherent interfaces with little loss of carrier mobility. The subsequent Se dopants introduce multiple phonon scattering sources and significantly suppress the lattice thermal conductivity while maintaining a decent power factor. Consequently, a high peak ZT of 1.53 at 350 K and a remarkable average ZT of 1.31 (300-500 K) are attained in the Bi0.4 Sb1.6 Te0.95 Se0.05 + 0.10 wt% Ag8 GeTe6 sample. Most noteworthily, the size and mass of the optimal sample are enlarged to Ø40 mm-200 g and the constructed 17-couple TE module exhibits an extraordinary conversion efficiency of 6.3% at ΔT = 245 K. This work demonstrates a facile method to develop high-performance and industrial-grade (Bi,Sb)2 Te3 -based alloys, which paves a strong way for further practical applications.
RESUMEN
To lower the introduction and maintenance costs of autonomous power supplies for driving Internet-of-things (IoT) devices, we have developed low-cost Fe-Al-Si-based thermoelectric (FAST) materials and power generation modules. Our development approach combines computational science, experiments, mapping measurements, and machine learning (ML). FAST materials have a good balance of mechanical properties and excellent chemical stability, superior to that of conventional Bi-Te-based materials. However, it remains challenging to enhance the power factor (PF) and lower the thermal conductivity of FAST materials to develop reliable power generation devices. This forum paper describes the current status of materials development based on experiments and ML with limited data, together with power generation module fabrication related to FAST materials with a view to commercialization. Combining bulk combinatorial methods with diffusion couple and mapping measurements could accelerate the search to enhance PF for FAST materials. We report that ML prediction is a powerful tool for finding unexpected off-stoichiometric compositions of the Fe-Al-Si system and dopant concentrations of a fourth element to enhance the PF, i.e., Co substitution for Fe atoms in FAST materials.
RESUMEN
Over the past few decades, rigorous efforts have been undertaken to develop novel thermoelectrics (TEs) with high conversion efficiencies. However, poor TE device efficiencies and use of scarce and toxic constituent elements in major TEs raises valid questions about their ecological effectiveness. We evaluate this efficacy by investigating environmental performance of seven TE modules, spanning five different TEs, on a diverse range of impacts (including toxicity and scarcity) over their life cycle (cradle-to-grave). Exhaustive inventory is developed for all modules, particularly their production and end-of-life stages, in the first-ever exercise of its kind till date, to assess their benefits for applications involving constant waste heat emission. Three end-of-life scenarios are considered to determine ecological benefits and pitfalls of recycling TEs, a first in LCA literature on thermoelectrics. The results show the dominance of specific constituent elements and large processing-related electricity consumption on impacts caused by production for all modules. Over their life cycle, TE modules are seen to exhibit large positive environmental benefits, barring some exceptions, highlighting their substantial eco-credentials independent of the TE used. Also, barring circular economy approach in some cases, no end-of-life treatment is observed to significantly influence modular environmental impacts. Subsequent calculations show ecological benefits from TEs to be comparable with those from commonly used renewables like solar and wind energy, with the findings repeated under scenario-based sensitivity analysis despite 50% reduction in conversion efficiency and 15% lowering in usage duration, further validating their ecofriendly potential. Simultaneously, two key challenges that hinder large-scale application of TEs - marginal ecological benefits (even on converting high fraction of waste heat to electricity) and high costs - are pointed out. This work concludes by highlighting the urgent need for addressing major negative contributors to production-related impacts of this platform to boost its prospects for commercial application and transform its ecofriendly potential into reality.
RESUMEN
Diamond-like compounds are a promising class of thermoelectric materials, very suitable for real applications. However, almost all high-performance diamond-like thermoelectric materials are p-type semiconductors. The lack of high-performance n-type diamond-like thermoelectric materials greatly restricts the fabrication of diamond-like material-based modules and their real applications. In this work, it is revealed that n-type AgInSe2 diamond-like compound has intrinsically high thermoelectric performance with a figure of merit (zT) of 1.1 at 900 K, comparable to the best p-type diamond-like thermoelectric materials reported before. Such high zT is mainly due to the ultralow lattice thermal conductivity, which is fundamentally limited by the low-frequency Ag-Se "cluster vibrations," as confirmed by ab initio lattice dynamic calculations. Doping Cd at Ag sites significantly improves the thermoelectric performance in the low and medium temperature ranges. By using such high-performance n-type AgInSe2-based compounds, the diamond-like thermoelectric module has been fabricated for the first time. An output power of 0.06 W under a temperature difference of 520 K between the two ends of the module is obtained. This work opens a new window for the applications using the diamond-like thermoelectric materials.
RESUMEN
Thermo-Electric Modules (TEMs) are being increasingly used in power generation as a valid alternative to batteries, providing autonomy to sensor nodes or entire Wireless Sensor Networks, especially for energy harvesting applications. Often, manufacturers provide some essential parameters under determined conditions, like for example, maximum temperature difference between the surfaces of the TEM or for maximum heat absorption, but in many cases, a TEM-based system is operated under the best conditions only for a fraction of the time, thus, when dynamic working conditions occur, the performance estimation of TEMs is crucial to determine their actual efficiency. The focus of this work is on using a novel procedure to estimate the parameters of both the electrical and thermal equivalent model and investigate their relationship with the operating temperature and the temperature gradient. The novelty of the method consists in the use of a simple test configuration to stimulate the modules and simultaneously acquire electrical and thermal data to obtain all parameters in a single test. Two different current profiles are proposed as possible stimuli, which use depends on the available test instrumentation, and relative performance are compared both quantitatively and qualitatively, in terms of standard deviation and estimation uncertainty. Obtained results, besides agreeing with both technical literature and a further estimation method based on module specifications, also provides the designer a detailed description of the module behavior, useful to simulate its performance in different scenarios.
RESUMEN
(TiZrHf)NiSn half-Heusler compounds were prepared by arc melting and their thermoelectric properties characterized in the temperature range between 325 K and 857 K, resulting in a Figure of Merit ZT ≈ 0.45. Furthermore, the prepared samples were used to construct a unileg module. This module was characterized in a homemade thermoelectric module measurement stand and yielded 275 mW/cm² and a maximum volumetric power density of 700 mW/cm³. This was reached using normal silver paint as a contacting material; from an improved contacting, much higher power yields are to be expected.
RESUMEN
Um condicionador de ar para biotérios foi montado com módulos termoelétricos de efeito Peltier. Para troca térmica foram empregados dissipadores externos a água, obtendo-se Δt de 21 ºC, rendimento de 46,02%, consumo de 524 W/h. A simulação matemática de operação, com mistura de ar não condicionado, mostrou que o sistema pode servir a aproximadamente 137 microisoladores padrão rato com dissipação externa a água. O sistema termoelétrico mostrou ainda, precisão de ± 0,1 ºC, nas temperaturas experimentais, o que é impossível num sistema de freon. Foram ensaiadas as seguintes temperaturas: 22º, 24º, 26º, 28º e 30 ºC, obtendo sempre estabilidade e precisão, independentemente da temperatura ambiental onde o equipamento estava em operação.
An air conditioner for animal facilities was mounted with thermoelectric modules of Peltier effect. For heat exchange, a water dissipation system was employed.The air temperature difference (Δt) was 21 ºC, the performance was 46.02% and the power consumption was 524 W/h. The mathematical simulation of operation, with mixture of no conditioned air showed that the system can serve approximately 137 standard mouse microisolators, with water dissipation system. The thermoelectric system also showed an accuracy of ± 0.1 ºC at the experimental temperatures, which is impossible in a system of Freon Gas. We tested the following temperatures: 22º, 24º, 26º, 28º and 30 ºC, always getting stability and accuracy at any outside temperature.