Supercapacitors, known as ultracapacitors, have been supposed to be one of the most promising candidates to meet requirements of human’s sustainable development, due to their advantages such as high ...capacitance and rate capability, long cycle life and low processing cost. Electrode materials play a decisive role on performance of supercapacitors, thus researches on electrode materials are critical to supercapacitors. Conducting polymer (CP) -based materials exhibit high potential in supercapacitors because of their unique advantages including good conductivity, flexibility, relatively cheap, easy of synthesis and so on. This review summarizes recent research progress of CPs (including polypyrrole (PPy), polyaniline (PANi), and polythiophene (PTh)), the CP-based binary composite, and the CP-based ternary composite electrode for supercapacitors. In the end, we give a brief outline of development directions of CP-based supercapacitors in the future.
The research progresses on three typical conducting polymers and their based composites for supercapacitor electrode materials were reviewed. Display omitted
•The most recent progress of electrodes materials for supercapacitors was reviewed.•The electrode materials include conducting polymers (CPs) and their based composites.•The conducting polymers include polyaniline, polypyrrole and polythiophene.•A brief outline of development directions of CP-based supercapacitors is also given.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Single-walled carbon nanotube (SWNT)/polyaniline (PANI) hybrid films were prepared by casting the suspension containing well-dispersed SWNTs and CSA-doped PANI. The electrical conductivity of the ...SWNT/PANI film at first increased with the increasing SWNT content and then decreased at high SWNT content, whereas the Seebeck coefficient increased monotonically in the present SWNT content range. Moreover, the electrical conductivity values of the SWNT/PANI composites were much higher than the values calculated based on the series-connected two-component mixture model, whereas the dependence of the Seebeck coefficient on the SWNT content fitted well with the mixture model. Thermal conductivities increased with the SWNT content, but the rate of increase was much lower than the values estimated using the mixture model. The maximum values of electrical conductivity and Seebeck coefficient of hybrid films were up to 769 S cm
−1
and 65 μV K
−1
. Consequently, the maximum thermoelectric power factor and
ZT
value at room temperature reached 176 μW m
−1
K
−2
and 0.12, respectively. The optimal TE property of the SWNT/PANI hybrid film was remarkably higher than those of either individual component of the composite, and exhibits the highest values for inorganic-organic composite materials reported so far. XRD and Raman analyses revealed that the PANI molecules in the composite film had a more expanded conformation, and were more orderly arranged compared with both pure PANI bulk and pure PANI film. The abnormally enhanced thermoelectric performance is attributed to the highly ordered PANI interface layer on the SWNT surface, which formed by the synergetic effect of chain expansion by the chemical interactions between PANI and the solvent and chain-ordering due to the π-π conjugation between PANI and CNTs.
The highly ordered PANI interface layer formed on a SWNT surface resulted in a remarkable increase of electrical conductivity and Seebeck coefficient. The optimal thermoelectric power factor and
ZT
value at room temperature reached 176 μW m
−1
K
−2
and 0.12, respectively.
Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for ...high-efficiency thermoelectric power generation. Here we report a high zT of ∼1.5 at 1,200 K for the p-type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron-phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm(-2) at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability.
Abstract
Researches on flexible thermoelectric materials usually focus on conducting polymers and conducting polymer-based composites; however, it is a great challenge to obtain high thermoelectric ...properties comparable to inorganic counterparts. Here, we report an n-type Ag
2
Se film on flexible nylon membrane with an ultrahigh power factor ~987.4 ± 104.1 μWm
−1
K
−2
at 300 K and an excellent flexibility (93% of the original electrical conductivity retention after 1000 bending cycles around a 8-mm diameter rod). The flexibility is attributed to a synergetic effect of the nylon membrane and the Ag
2
Se film intertwined with numerous high-aspect-ratio Ag
2
Se grains. A thermoelectric prototype composed of 4-leg of the Ag
2
Se film generates a voltage and a maximum power of 18 mV and 460 nW, respectively, at a temperature difference of 30 K. This work opens opportunities of searching for high performance thermoelectric film for flexible thermoelectric devices.
In this work, single-walled carbon nanotube (SWCNT)/PEDOT:PSS coated Te nanorod (PC-Te) composite films were prepared by a simple vacuum assisted filtration method, and H2SO4 treatment was employed ...to improve the thermoelectric performance of the composite films. The addition of SWCNTs apparently improved the electrical conductivity while reduced the Seebeck coefficient of the composite films, resulting in a reduction of the power factor. After treated with H2SO4, the electrical conductivity of the composite films was further improved, and the Seebeck coefficient decreased slightly. As a consequence, an optimized power factor of 104 μW/mK2 (corresponding to the electrical conductivity of 332 S/cm and Seebeck coefficient of 56 μV/K, respectively) was obtained for the sample containing 70 wt% SWCNTs at 300 K. A flexible thermoelectric generator prototype was fabricated to demonstrate the output properties. The open circuit voltage and maximum output power delivered from the prototype were 5.6 mV and 53.6 nW, respectively, at a temperature difference of 44 K.
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•SWCNT/PEDOT:PSS coated Te nanorod composite films were prepared.•Electrical conductivity of the films increased with the addition of SWCNT.•Sulfuric acid treatment improved the thermoelectric performance of the composite films.•An optimized power factor of 104 μW/mK2 was obtained at 300 K.•A flexible thermoelectric power generator prototype was fabricated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
The urgent need for ecofriendly, stable, long‐lifetime power sources is driving the booming market for miniaturized and integrated electronics, including wearable and medical implantable devices. ...Flexible thermoelectric materials and devices are receiving increasing attention, due to their capability to convert heat into electricity directly by conformably attaching them onto heat sources. Polymer‐based flexible thermoelectric materials are particularly fascinating because of their intrinsic flexibility, affordability, and low toxicity. There are other promising alternatives including inorganic‐based flexible thermoelectrics that have high energy‐conversion efficiency, large power output, and stability at relatively high temperature. Herein, the state‐of‐the‐art in the development of flexible thermoelectric materials and devices is summarized, including exploring the fundamentals behind the performance of flexible thermoelectric materials and devices by relating materials chemistry and physics to properties. By taking insights from carrier and phonon transport, the limitations of high‐performance flexible thermoelectric materials and the underlying mechanisms associated with each optimization strategy are highlighted. Finally, the remaining challenges in flexible thermoelectric materials are discussed in conclusion, and suggestions and a framework to guide future development are provided, which may pave the way for a bright future for flexible thermoelectric devices in the energy market.
A comprehensive exploration of the material design strategies, processing methods, and underlying physics and chemistry behind the enhanced thermoelectric properties of flexible thermoelectric materials is presented, emphasizing innovative approaches and suggesting future pathways for the development of a new generation of wearable electronics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Flexible thermoelectrics provide a different solution for developing portable and sustainable flexible power supplies. The discovery of silver sulfide–based ductile semiconductors has driven a shift ...in the potential for flexible thermoelectrics, but the lack of good p-type ductile thermoelectric materials has restricted the reality of fabricating conventional cross-plane π-shaped flexible devices. We report a series of high-performance p-type ductile thermoelectric materials based on the composition-performance phase diagram in AgCu(Se,S,Te) pseudoternary solid solutions, with high figure-of-merit values (0.45 at 300 kelvin and 0.68 at 340 kelvin) compared with other flexible thermoelectric materials. We further demonstrate thin and flexible π-shaped devices with a maximum normalized power density that reaches 30 μW cm
−2
K
−2
. This output is promising for the use of flexible thermoelectrics in wearable electronics.
A flexible power source
Thermoelectric materials can harvest heat and turn it into power. Heat sources potentially include the heat generated by humans through wearable devices and might enable self-powering systems, but the lack of ductility for most thermoelectrics poses a major problem. Yang
et al
. found a thermoelectric silver/copper–based semiconductor that also is ductile (see the Perspective by Hou and Zhu). This material allows for a thin, flexible device capable of producing power, even when adhered to a wrist. —BG
A flexible thermoelectric was developed from a silver/copper–based semiconductor that can be fashioned into a thin device.
Hybrid nanocomposites containing carbon nanotubes (CNTs) and ordered polyaniline (PANI) have been prepared through an in situ polymerization reaction using a single-walled nanotube (SWNT) as template ...and aniline as reactant. TEM, SEM, XRD, and Raman analyses show that the polyaniline grew along the surface of CNTs forming an ordered chain structure during the SWNT-directed polymerization process. The SWNT/PANI nanocomposites show both higher electrical conductivity and Seebeck coefficient as compared to pure PANI, which could be attributed to the enhanced carrier mobility in the ordered chain structures of the PANI. The maximum electrical conductivity and Seebeck coefficient of composites reach 1.25 × 104 S m−1 and 40 μV K−1, respectively, and the maximum power factor is up to 2 × 10−5 W m−1 K−2, more than 2 orders of magnitude higher than the pure polyaniline. This study suggests that constructing highly ordered chain structure is a novel and effective way for improving the thermoelectric properties of conducting polymers.
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IJS, KILJ, NUK, PNG, UL, UM
PEDOT:PSS coated Te (PCTe) nanorod/PEDOT:PSS composite films were prepared by a drop-casting technique. H2SO4 treatment was employed to enhance thermoelectric (TE) properties of the composite films. ...The addition of PCTe nanorods increased both the electrical conductivity and the Seebeck coefficient of the composite films. An optimized power factor of 141.9 μW/mK2 was obtained for the film containing 90 wt% PCTe nanorods treated with 12 M H2SO4 at room temperature, which was 2.75 times as high as that of the untreated composite film, corresponding to the electrical conductivity and Seebeck coefficient of 204.6 S/cm and 83.27 μV/K, respectively. XPS and GIWAXS analysis revealed the removal of insulating PSS units and the rearrangement of PEDOT chains after the H2SO4 treatment. Finally, a 9-leg TE generator prototype was fabricated using the optimized composite film. The maximum output power and area output power density produced from the prototype were 47.7 nW and 57.2 μW/cm2, respectively, at the temperature difference of 40 K.
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•PEDOT:PSS coated Te (PCTe) nanorods were synthesized.•PCTe/PEDOT:PSS composite films were prepared by a drop-casting method.•H2SO4 treatment was used to enhance TE properties of the composite films.•An optimized power factor of 141.9 μW/mK2 was obtained.•A flexible thermoelectric generator prototype was fabricated using the optimized film.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In recent decades, by continuously enhancing the figure of merit ZT of various thermoelectric (TE) materials, solid state TE technology has matured and is on the verge of making an impact in real ...industrial settings as a promising approach to harvest waste industrial heat and convert it to useful electricity. Nevertheless, actual TE module development has remained stagnant with rather poor efficiencies. This has raised an urgent need to design rational module structures that rely on complex parameter optimization and utilization of efficient integration technologies that minimize energy losses during bonding of various interfaces. Here, we demonstrate a three-dimensional numerical analysis model of a segmented TE power-generating device, which takes into account the temperature-dependent materials' properties and various parasitic losses. The model generates an optimized design with predictive performance to realize maximum conversion efficiency. Combined with the developed bonding schemes and assembly techniques, the segmented modules consisting of Bi2Te3-based alloys and CoSb3-based filled skutterudites were successfully fabricated with a record-high efficiency of up to 12% when operating under a temperature difference of 541 degree C. The rational structure design based on the numerical analysis model and the extremely low thermal and electrical losses enable the heat-to-electricity conversion efficiency to reach up to 96.9% of the theoretical efficiency based on the TE materials themselves. These findings highlight the importance of the optimization strategy for TE power generation devices based on the TE materials' intrinsic properties and demonstrate that realistic high temperature TE modules with predictive high efficiency and high power density can be fabricated, which provides a useful guide to achieve a high conversion efficiency in large-scale TE applications.
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