High Seebeck Coefficient Research Articles

A New Type of CuNi/TiB2 Thin-Film Thermocouple Fabricated by Magnetron Sputtering

A new CuNi/TiB2 thin-film thermocouple was fabricated using magnetron sputtering. A 400 nm thick CuNi interior layer was deposited on a dielectric substrate initiatory, and then covered by an 800 nm thick TiB2 layer. The tests revealed that the TiB2 layer had a dense and columnar cross-section. The measured hardness and elastic modulus of the TiB2 layer were ~20.5 and 315.9 GPa, respectively. No cracking or delamination occurred at the CuNi/TiB2 interface. The work functions of the TiB2 and the CuNi layers were calculated to be 4.406 and 4.726 eV, respectively. The difference in work functions between the TiB2 and the CuNi was ~0.3 eV. The CuNi/TiB2 thin-film sensor exhibited a high Seebeck coefficient of 38.07 μV/°C with excellent linearity. The maximum service temperature of the thin-film sensor was evaluated to be ~400 °C. A further increase in temperature degraded the Seebeck coefficient due to oxidation of the TiB2 layer.

Bandgap‐Dependent Doping of Semiconducting Carbon Nanotube Networks by Proton‐Coupled Electron Transfer for Stable Thermoelectrics

AbstractNetworks of semiconducting single‐walled carbon nanotubes (SWNTs) are a promising material for thermoelectric energy harvesting due to their mechanical flexibility, solution processability, high Seebeck coefficients and high electrical conductivities after chemical p‐ or n‐doping. Here, we demonstrate that proton‐coupled electron transfer (PCET) with benzoquinone (BQ) as the oxidant and lithium bis(trifluoromethylsulfonyl)imide (Li[TFSI]) for electrolyte counterions is a highly suitable method for p‐doping of polymer‐sorted semiconducting SWNT networks. The achieved doping levels, as determined from absorption bleaching, depend directly on both the pH of the aqueous doping solutions and the bandgap (i.e., diameter) of the nanotubes within the network. Fast screening of different nanotube networks under various doping conditions is enabled by a high‐throughput setup for thermoelectric measurements of five samples in parallel. For small‐bandgap SWNTs, PCET‐doping is sufficient to reach the maximum thermoelectric power factors, which are equal to those obtained by conventional methods. In contrast to other doping methods, the electrical conductivity of PCET‐doped SWNTs remains stable over at least 5 days in air. These results confirm PCET to be a suitable approach for more environmentally friendly and stable doping of semiconducting SWNTs as promising thermoelectric materials.

Large Improvements in the Thermoelectric Properties of SnSe by Fast Cooling.

As reported during the last five years, SnSe is one of the leading thermoelectric (TE) materials with a very low lattice thermal conductivity. However, its elements are not as heavy as those of classical thermoelectric materials like PbTe or Bi2Te3. Its outstanding TE properties were revealed after repeated purification steps to minimize the amount of oxygen contamination, followed by spark plasma sintering. Recently, we showed that hot-pressing-once optimized-can yield comparable or even better TE performance using the examples of Na- and Cu- as well as Na- and Ag-co-doped SnSe. However, long-term stability remains a challenge during cycling between low and high temperatures. Here, we investigated whether the cooling procedure has a significant impact on the thermoelectric properties of SnSe. We compared cooling of the melt with a 1:1 ratio of Sn:Se from 1273 K down to room temperature in air with quenching in water. As typical for undoped SnSe, both materials were extrinsic p-type semiconductors due to Sn defects. The air-quenched sample exhibited higher thermal conductivity, lower electrical conductivity, and higher Seebeck coefficient, all consistent with a smaller number of defects and thus a smaller number of charge carriers due to the slower cooling procedure. This resulted in a comparatively low peak figure-of-merit value zT of 0.61 at 823 K for the air-quenched sample, compared to the substantially higher peak zT of 1.58 at 813 K for the water-quenched sample.

Dual-Mode Textile Sensor Based on PEDOT:PSS/SWCNTs Composites for Pressure-Temperature Detection.

As an innovative branch of electronics, intelligent electronic textiles (e-textiles) have broad prospects in applications such as e-skin, human-computer interaction, and smart homes. However, it is still a challenge to distinguish multiple stimuli in the same e-textile. Herein, we propose a dual-parameter smart e-textile that can detect human pulse and body temperature in real time, with high performance and no signal interference. The doping of SWCNTs in PEDOT:PSS improves the electrical conductivity and Seebeck coefficient of the prepared composites, which results in excellent pressure and temperature-sensing properties of the PEDOT:PSS/SWCNTs/CS@PET-textile (PSCP) sensor. The dual-mode sensor has high sensitivity (32.4 kPa-1), fast response time (~21 ms), and excellent durability (>2000 times) in pressure detection. Concurrently, this sensor maintains a high Seebeck coefficient of 25 μV/K in the 0-120 K temperature range with a tremendous linear relationship. Based on impressive dual-mode sensing characteristics and independent temperature-difference- and pressure-sensing mechanisms, smart e-textile sensors realize the real-time simultaneous monitoring of weak pulse signals and human body temperature, showing great potential in medical healthcare. In addition, the potential energy is excited by the temperature gradient between the human skin and the environment, which provides a novel idea for wearable self-powered devices.

Boosting thermoelectric properties of n-type PbS across a broad temperature range through doping with trace amounts of InBi

Lead sulfide (PbS) is a promising thermoelectric material due to its high availability, thermal stability, and cost-efficiency, with research predominantly aiming to enhance its carrier concentration through heavy doping for optimal ZT values at high temperatures. However, this approach often results in suboptimal performance at ambient temperature, significantly constraining its applicability in thermoelectric cooling technologies. In this work, the carrier concentration of n-type PbS is optimized by incorporating trace amounts of InBi. Due to the low carrier concentration, PbS retains a high Seebeck coefficient and carrier mobility, resulting in a high average power factor (PFave) of 15.4 μW·cm−1·K−2 within the temperature range from 300 to 773 K. In addition, the introduction of In/Bi interstitial atoms and dislocation defects enhances phonon scattering, effectively reducing the lattice thermal conductivity of PbS. The peak ZT value of Pb0.999(InBi)0.001S at 773 K reaches ∼1.0, while an average ZT value (ZTave) of ∼0.6 is achieved between 300 and 773 K in Pb0.9995(InBi)0.0005S. This study demonstrates that trace element doping is an effective strategy for optimizing the thermoelectric performance of PbS across a wide temperature range, which is vital in the thermoelectric power generation and refrigeration application.

Achieving Superior Thermoelectric Performance in Methoxy-Functionalized MXenes: The Role of Organic Functionalization.

Thermoelectric technology enables the direct and reversible conversion of heat into electrical energy without air pollution. Herein, the stability, electronic structure, and thermoelectric properties of methoxy-functionalized M2C(OMe)2 (M = Sc, Ti, V, Cr, Y, Zr, Nb, Mo, Hf, Ta, and W) were systematically investigated using first-principles calculations and semiclassical Boltzmann transport theory. All MXenes, except those with M = Cr, Mo, and W, can be synthesized by substituting Cl- and Br-functionalized MXenes with deprotonated methanol, with stability governed by the M-O bond strength. Notably, semiconductors Sc2C(OMe)2 and Y2C(OMe)2 exhibit exceptionally high peak ZT values of 15.02 and 12.11 under n-type doping at 900 K, achieving a remarkable thermoelectric conversion efficiency of 53% at a temperature difference of 600 K, outperforming current high-performance thermoelectric materials. This superior performance is attributed to the weak electron-withdrawing nature of the methoxy group, which enhances nonbonding d electrons, combined with flat and degenerate band edges, and strong coupling between acoustic and optical phonons. Together, these features sustain a high Seebeck coefficient, improve electrical conductivity, and suppress lattice thermal conductivity. These findings present an effective organic functionalization strategy for designing high-performance MXenes for industrial applications and offer valuable insights for developing next-generation thermoelectric materials.

DFT+NEGF Insights on Boosting the Thermoelectric Figure of Merit of 2D GeTe/arsenene vdW Heterostructure Device: Interface Engineering

Stacking two-dimensional materials into van der Waal heterostructures (vdWH) is a promising choice for thermoelectric devices. Applying the first-principles method with NEGF formalism, we examined the structural, electronic study, and thermoelectrical transport features of the GeTe/arsenene 2D vdW heterostructure and its constituent monolayer. Heterostructures are constructed by combining GeTe with arsenene (AS) monolayers through vdW stacking using the Coincident site lattice (CSL) theory. The stability of these vdWH is proven by the parameters of interlayer distances, binding energies, and dynamical stability. The stable heterostructure exhibits an indirect bandgap (0.41 eV) with a band-type-II profile. A two-probe device model of the armchair (AC_vdWH) and zigzag (ZZ_vdWH) oriented systems are constructed to examine the thermoelectric transport properties. The thermoelectric transport properties are discussed in terms of different temperatures and chemical potentials. The negative Seebeck coefficient of the systems depicts an n-type character. Thermoelectric studies indicate that the AC_vdWH improves performance due to a reduction in phonon transmittance (26.83 nW/K) and a high Seebeck coefficient (-384.7 μV/K) at room temperature. Our findings predict that n-type AC_GeTe/arsenene vdWH with a high ZT value of 4.4 at 400 K, will be the promising choice for low-temperature thermoelectric device applications.

Advancements in Ge-based thermoelectric materials for efficient waste heat energy conversion: a comprehensive review

Abstract Thermoelectric materials hold significant promise for converting waste heat energy into electrical energy. The performance of these materials and devices is assessed using a quantitative measure known as the figure of merit, which relies on the Seebeck coefficient, thermal conductivity, and electrical conductivity of the material. Different classes of thermoelectric materials have their own merits and demerits. High temperature thermoelectric materials are useful for space exploration, automobile applications, etc Many materials have been explored within temperature range of 300–900 K, showing suitable properties for thermoelectric applications. Germanium, an inorganic material is investigated in details, due to its high Seebeck coefficient and better thermal stability. Silicon-Germanium alloys are thermoelectric materials suitable for operating at high temperatures. These materials help in reduction of emission of green house gases. Extensive efforts have been devoted to enhance the efficiency of Germanium-based thermoelectric materials and devices through various techniques such as doping, nanostructuring, electron energy filtering, and band engineering. Recently, a new material Ge0.94Sm0.06Te has been introduced, reporting a high figure of merit value of 2.5 at 730 K. Many theoretical studies are also reported showing the potential of new Germanium-based thermoelectric materials. Further, 2D Germanium-based materials show enhanced thermoelectric properties as well. These findings underscore the significance of Germanium as a thermoelectric material. This review provides an overview of the latest developments in Germanium-based thermoelectric materials and focuses on different strategies to enhance their thermoelectric performance. Additionally, the suitability of various Germanium-based thermoelectric materials in comparison to other materials for energy harvesting applications is extensively discussed in this review.

High-Quality SnSe Thin Films for Self-Powered Devices and Multilevel Information Encryption.

As semiconductor technology advances toward miniaturization and portability, thin films with excellent thermoelectric performance have garnered increasing attention, particularly for applications in self-powered devices and temperature-responsive sensors. The high Seebeck coefficient of SnSe thin films makes them promising for temperature sensing, but their poor electrical conductivity limits their potential as thermoelectric generators. In this work, high-quality a-axis oriented SnSe thin films were deposited on quartz substrates by using magnetron sputtering. The substrate temperature was optimized to improve the crystallinity of the SnSe thin film, resulting in larger grain sizes, which subsequently contributes to the improved carrier mobility. The Seebeck coefficient is enhanced while optimizing the electrical conductivity, enabling the SnSe thin film to achieve both excellent sensing and power generation performance. The SnSe film deposited at 673 K exhibits a high power factor of approximately 346 μW m-1 K-2 at 620 K. A temperature-responsive sensing array was developed for multilevel information encryption, showing significant potential for applications in password encryption. The maximum output power density of the optimized thermoelectric generator with six SnSe legs is about 9 W m-2 at a temperature difference of 50 K.

Ionic Thermoelectric-Powered Resistive Sensors.

Ionic thermoelectric supercapacitors (ITESCs) are noted for their high ionic Seebeck coefficient (α) to convert thermal energy into electrical current through charging. This work demonstrates the utilization of the charging and discharging current from ITESCs to directly operate resistive sensors. The humidity monitoring is powered by applying a periodic temperature gradient to a connected ITESC. By leveraging these properties and residual environmental heat, ITESCs can offer a promising method for autonomously powered portable sensors.

Improved thermoelectric performance of nanostructured tellurium thin films

AbstractWe report nanostructured Te thin film exhibiting a high figure-of-merit (ZT) of ~ 0.34 at 493 K. The films exhibit temperature enhanced electrical conductivity ~ 43 Scm−1, very high Seebeck coefficient of ~ 385 µV−1K−1 contributed by non-degenerate valence bands and low thermal conductivity ~ 0.9−1 Wm−1K−1 through suppression of bipolar effect. The ZT of nanostructured films is ~ 142% higher than the annealed films having larger grain size. The high Seebeck coefficient (~ 405 µV−1K−1) of nanostructured Te films near room temperature prompted us to make a device, which was subjected to a very small temperature difference of ~ 4 K by touching with finger and produced an open circuit voltage of ~ 18 mV. The periodic generation of this open circuit voltage with fast response when repeatedly touched with finger, suggest the utility of these films in real time human touch applications and temperature sensing.

Realization of Hydrogel Electrolytes with High Thermoelectric Properties: Utilization of the Hofmeister Effect.

Ionic thermoelectric materials, renowned for their high Seebeck coefficients, are gaining prominence for their potential in harvesting low-grade waste heat. However, the theoretical underpinnings for enhancing the performance of these materials remain underexplored. In this study, the Hoffmeister effect was leveraged to augment the thermoelectric properties of hydrogel-based ionic thermoelectric materials. A series of PAAm-x Zn(CF3SO3)2, PAAm-x ZnSO4, and PAAm-x Zn(ClO4)2 hydrogels were synthesized, using polyacrylamide (PAAm) as the matrix and three distinct zinc salts with varying anion volumes to impart the Hoffmeister effect. Exceptionally, the most cost-effective ZnSO4 yielded the highest ionic Seebeck coefficient among the hydrogels, with PAAm-1 ZnSO4 achieving a remarkable value of -3.72 mV K-1. To elucidate the underlying mechanism, we conducted an innovative analysis correlating the Seebeck coefficient with the zinc ion transfer number. Additionally, the hydrogel materials demonstrated outstanding mechanical properties, including high elongation at break (>1400% at its peak), exceptional resilience (virtually no hysteresis loops), and robust fatigue resistance (overlapping cyclic tensile curves). This work not only advances the understanding of ionic thermoelectric materials but also showcases the potential of hydrogels for practical waste heat recovery applications.

Fiber-Shaped Temperature Sensor with High Seebeck Coefficient for Human Health and Safety Monitoring.

Wearable thermoelectric (TE)-based temperature sensors capable of detecting and transmitting temperature data from the human body and environment show promise in intelligent medical systems, human-machine interfaces, and electronic skins. However, it has remained a challenge to fabricate the flexible temperature sensors with superior sensing performance, primarily due to the low Seebeck coefficient of the TE materials. Here, we report an inorganic amorphous TE material, Ge5As55Te40, with a high Seebeck coefficient of 1050 μV/K, which is around 3 times higher than the organic TE materials and 2 times higher than the inorganic crystal TE materials. Due to the strong anticrystallization ability, the amorphous state of Ge5As55Te40 can be well maintained during the thermal fiber-drawing process. The resulting TE fibers demonstrate superior temperature sensing properties, encompassing a broad working range (25-115 °C), a precise temperature resolution of 0.1 K, and a rapid response time of 5 s. Importantly, the TE properties of the fiber show high stability after repeated temperature variations between 5 and 10 K. Moreover, the fibers can be integrated into a mask and a wearable fabric for monitoring human respiratory rate and providing early warning for fire source proximity. These results highlight that the TE fiber with both natural flexibility and superior temperature sensing performance may find potential applications in wearable systems.

Structural, electronic, magnetic, optical and thermoelectric properties of ferromagnetic double perovskites K2ScCoX6 (X = F, Cl): A first-principles study

To identify a promising alternative to lead-based materials for solar cell application, we investigated the different physical properties of K2ScCoX6 (X = F, Cl) perovskites. Both materials have ferromagnetic ground state. The obtained optimize lattice constants are found to be 8.48 Å and 10.04 Å for K2ScCoF6 and K2ScCoCl6 respectively. Our finding indicate that these materials exhibit excellent structural, mechanical, the thermal stability, as evidenced by their Goldsmith’s tolerance factor, elastic parameters, and negative formation energies. The formation energy is found to be -2.4 and -2.1 eV/atom for K2ScCoF6 and K2ScCoCl6 respectively. The electronic properties reveals that both materials have semiconducting nature. Notably, we observed low direct bandgap of 0.93 eV for K2ScCoF6 and 1.22 eV for K2ScCoCl6, which contrast with the typically large bandgap values reported for most halide double perovskite. The calculated values of Poisson’s and Pugh’s ratios, along with positive Cauchy’s pressure, suggest a ductile nature for these compounds. Additionally, the optical properties show high absorption and optical conductivity, coupled with low reflectivity and minimal energy loss in lower energy ranges. These results suggest that the halogen-based double perovskite materials have significant potential as photovoltaic absorber materials in solar cell applications. Furthermore, their higher Seebeck coefficients, power factors and low thermal conductivity at room temperature underscore their potential for thermoelectric applications.

Mechanical, electronic, optical, and thermoelectric properties of Rb2TlGaX6 (X = F, I) lead-free double perovskites: a first-principles study

Abstract Halide perovskites play an important role in the renewable energy industry and are the top substitutes for Pb-halide perovskites. This study investigates the structural, mechanical, electronic, optical, and thermoelectric properties of the double halide perovskites Rb2TlGaX6 (X = F, I) using density functional theory (DFT) at WIEN2k interfaces. The structural, mechanical, and thermal stabilities are evaluated using the tolerance factor, Born-Huang criteria, and negative formation energy. The obtained lattice constants are 9.31 Å and 24.93 Å, for Rb2TlGaF6 and Rb2TlGaI6 respectively. Rb2TlGaF6 is brittle and Rb2TlGaI6 is ductile. Both compounds exhibit anisotropic behavior. The indirect semiconducting nature (L-X) is demonstrated by the estimated bandgap values of 6.05 eV (4.31 eV) and 1.06 eV (0.52 eV), for Rb2TlGaF6 and Rb2TlGaI6 respectively, using the TB-mBJ (PBE-GGA) potential. Distinctive optical characteristics are studied, including the dielectric function, loss function, conductivity, reflectivity, refractive index, and absorption coefficient. Based on the investigation, both materials exhibit excellent optical conductivity, high light absorption throughout the UV–visible spectrum, and low reflection (within 20% for Rb2TlGaF6 and 40% for Rb2TlGaI6). Lastly, various thermoelectric properties are explored by varying the temperature. Both compounds show a high Seebeck coefficient and low thermal conductivity. The maximum figure of merit (ZT) obtains of 0.61 and 0.81, for Rb2TlGaF6 and Rb2TlGaI6, respectively. These results demonstrate the suitability of Rb2TlGaF6 and Rb2TlGaI6 for thermoelectric and photovoltaic applications.

Theoretical insights into Sb2Te3/Te van der Waals heterostructures for achieving very high figure of merit and conversion efficiency

Thermoelectric technology offers a promising solution for sustainable energy conversion, but maximizing efficiency and figure of merit (ZT) remains a significant challenge. This work explores the novel structural, electronic, and thermoelectric properties of Sb2Te3/Te van der Waals heterostructures (vdWHs) through first-principles computation and Boltzmann transport theory. Our study reveals that the Sb2Te3/Te vdWHs exhibit very low lattice thermal conductivity (0.28 Wm−1K−1) and high Seebeck coefficient (811 μVK−1), driven by energy-filtering effects across the interface and a band gap of 0.47 eV. Notably, the calculated ZT reaches a record-high value of 8.83 at 400 K, substantially surpassing previous benchmarks for similar materials. Unlike prior studies, we extend our investigation by tuning the dimensions to 2 × 2 × 1 and 3 × 3 × 1 supercells and exploring tri-layer Te/Sb2Te3/Te vdWHs. Our results show that the ZT of the 2 × 2 × 1 supercell reaches an even higher value of 9.14, further exceeding the performance of the unit cell. Additionally, the heterostructures demonstrate a remarkable thermoelectric conversion efficiency (η) of 32.25 % and thermionic refrigeration efficiency surpassing 51.9 % of Carnot efficiency at 400 K, highlighting their potential for high-performance cooling applications. These findings significantly advance the integration of high-efficiency heat-to-electricity conversion and cooling within a single material system, setting a new benchmark for thermoelectric performance and establishing Sb₂Te₃/Te vdWHs as a leading candidate for next-generation thermoelectric and electronic technologies.

Inspecting the structural stability, magneto-opto-electronic, and transport characteristics of half-metallic ferromagnets double perovskite oxide (Sr2MoSbO6): A DFT study

The structural, elastic, mechanical, electronic, thermoelectric, and magnetic properties of the double perovskite Sr2MoSbO6 have investigated in this manuscript using Perdew-Burke-Ernzerhof Generalized Gradient Approximation (PBE-GGA) with an enhanced Trans Blaha modified Becke Johnson potential (TB-mBJ) approach. Through electro-magnetic and elastic exploration, we have determined that this compound is semiconductor, ferromagnetic, and brittle. Strong hybridisation between the Mo and Sr-d orbitals was seen in the Density of states (DOS) results, which, according to their relative quantities, supports the two states' ionic nature. The Mo atoms contribute significantly to the overall magnetic moment, which is 3.0 μB in total. The semiconducting nature of Sr2MoSbO6 is confirmed by the calculation of the overall electronic parameters. Calculations of thermodynamic parameters for temperature ranges of 0–1200 K and pressure ranges of roughly 0–30 GPa show good agreement between theoretical and experimental data. The DFT Boltzmann transport equations have been used to compute thermoelectric properties in relation to temperature and chemical potential. The p-type character of Sr2MoSbO6 is identified by positive values of the Seebeck coefficient. The power factor (PF), Seebeck coefficient (S), figure of merit (ZT), electrical conductivity, and lattice thermal conductivity were also calculated. It was discovered that this perovskite had a merit figure that was almost equal to one, a very high Seebeck coefficient, and strong electrical conductivity—all of which are consistent with its semiconductor nature. These findings suggest a substance with a great deal of promise for thermoelectrical uses. The results are taken into consideration for future experiments and may be future candidates for spintronics applications.

Impact of porous silicon thickness on thermoelectric properties of silicon-germanium alloy films produced by electrochemical deposition of germanium into porous silicon matrices followed by rapid thermal annealing

Silicon-germanium alloy films were formed by electrochemical deposition of germanium into porous silicon matrices with thicknesses varying from 1.5 to 10 μm followed by subsequent rapid thermal processing at 950 °C in an inert atmosphere. Study of the fabricated structures using SEM and Raman spectroscopy, as well as measurements of their electrical conductivity and thermoelectric properties revealed that the highest Seebeck coefficient (−505 μV/K at 450 K) and Power Factor (1950 μW/(m·K2) at 400 K) values were obtained when a 5 μm-thick porous silicon was used as a structural matrix. Under such conditions, an optimal balance between electrical conductivity, structural disorder and electrical insulation from the substrate is achieved due to the presence of a residual porous underlayer, making it possible to maximize the film's thermoelectric performance. The obtained silicon-germanium alloy films are deemed suitable for the fabrication of both discrete and integrated thermoelectric devices based on monocrystalline silicon substrates.

Enhanced thermoelectric properties of Bi1.92Li0.08Sr2Co2Oy/x wt% SiC composites

In this work, Bi1.92Li0.08Sr2Co2Oy/x wt% SiC (1.0 ≤ x ≤ 4.0 wt%) composites are fabricated through a solid-state reaction followed by spark plasma sintering. The resulting composites exhibit plate-like grains and high density. The addition of SiC nanoparticles reduces electrical conductivity due to decreased hole mobility and increases the Seebeck coefficient due to an enhanced scattering factor and effective mass. Furthermore, the incorporation of SiC nanoparticles significantly enhances phonon scattering, thereby reducing phonon thermal conductivity. The Bi1.92Li0.08Sr2Co2Oy/2.0 wt% SiC composite exhibits the largest ZT of 0.17 at 973 K due to its high Seebeck coefficient and low thermal conductivity. Our results demonstrate that incorporating SiC nanoparticles is a highly effective strategy for enhancing the thermoelectric properties of Bi1.92Li0.08Sr2Co2Oy.

Numerical study on heat and ion transport characteristics enables optimal design of aqueous thermocells for low-grade heat recovery

As a cutting-edge heat-to-electricity technology, thermogalvanic cells (thermocells) have great prospects in low-grade heat recovery due to its high Seebeck coefficient (Se), high scalability and low cost. Most of previous studies about aqueous thermocells have been focused on the overall performance by experimentally exploring advanced electrode and electrolyte materials, while very few simulation studies were reported before, leading to the unclear mechanisms of heat and ion transport inside the thermocell. In view of these challenges, this study aims to reveal the heat and ion transport characteristics of aqueous thermocells under various critical operating parameters, providing theoretical guidelines for further design and optimization of aqueous thermocells with fixed electrode and electrolyte materials. Firstly, a multi-physical model considering the diffusion, migration and convection was established and validated. Then, the effects of hot electrode temperature, electrode spacing and electrode orientation were evaluated on the thermocell performance from the aspects of distributions of multi-physical fields, overpotentials and overall performance. Finally, a prototype aqueous thermocell was proposed based on the understandings of restrictions associated with these operating parameters. Results indicated that each operating parameter can attribute to the variation of natural convection from the intensity and forms, and then affected the ion transport flux and overpotentials, and thus determined the power density of thermocells. These findings prompted the design and optimization of new aqueous thermocells, and the proposed prototype thermocell delivered the maximum power density of 0.43 W/m2, which was 115 % higher than that of the basic rectangular thermocell.