High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

Im, Hyoung June; Kim, Taewoo; Song, Hyelynn; Choi, Jong‐Ho; Park, Jae Sung; Ovalle‐Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

doi:10.1038/ncomms10600

Cited by 278 publications

(191 citation statements)

References 34 publications

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“…Seebeck coefficient measured through U-shape thermoelectric cell was 1.43 mV/K (Figure 3d), in good agreement with previous reports [47,52]. The performance of the thermocell was mainly evaluated by the following two key parameters: the maximum output power (Pmax) and the relative power conversion efficiency (ηr).…”

supporting

confidence: 90%

Section: Thermoelectric Cellsmentioning

confidence: 99%

“…The faradaic peak current of the graphene-linked hollow carbon sphere aerogels is higher than that of graphene aerogel and that of hollow carbon sphere, indicating best electrochemical behavior among these electrode materials [46]. The ESA could be derived from the RandlesSevcik equation [47] given by:Ip=2.69×10 5 ×ESA×D 1/2 ×n 3/2 ×ν 1/2 ×C (1) where Ip is the faradaic peak current, D is the diffusion coefficient, n is the number of electrons transferred during the redox reaction, ν is the potential scan rate, and C is the concentration of 13 probe molecule. Analysis of the CV curve using the equation (1) showed that the GHCS-aerogel electrode possessed a higher ESA (see Figure S11), which may ascribe to both hollow core, and microporous shell of the submicron-sized spherical building blocks as well as the large surface of 2D graphene.…”

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confidence: 99%

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Assembling hollow carbon sphere-graphene polylithic aerogels for thermoelectric cells

Dong

Guo

et al. 2017

Nano Energy

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Aerogels are highly porous bulk materials assembled chemically or physically with various nanoscale building blocks and thus hold promise for numerous applications including energy storage and conversion. Assembling of hollow or porous particles with the diameter larger than 100 nm into hierarchically porous aerogels is efficient but challenging for achieving a high specific surface of aerogel. In this regard, submicron-sized carbon spheres with hollow cores and microporous shells are assembled into bulk aerogels, for the first time, in the presence of twodimensional graphene sheets as special cross-linkers. The resulting bead-to-sheet polylithic aerogels show ultra-low density (51-67 mg·cm -3 ), high conductivity (263-695 S·m -1 ) and high specific surface area (569-609 m 2 ·g -1 ). An application of thermocells is demonstrated with maximum output power of 1.05 W·m -2 and maximum energy conversion efficiency of 1.4 % relative to Carnot engine, outperforming the current simple U-shaped thermocells reported elsewhere.3 1.IntroductionGradual exhaustion of fossil fuels and rapid increase of energy demand may cause a serious energy crisis in the very near future [1]. Either exploiting the new energy options or developing energy recycling is a highly efficient way to overcome increasingly grim energy crisis [2][3][4][5][6].However, both technologies face the challenge of finding and integrating new materials to meet the demanding performance [7,8]. This constantly motivates scientists to develop novel energy materials [9][10][11][12].An aerogel is a kind of highly porous nanomaterial [13] with many intriguing properties such as the high specific surface area (more than several hundred m 2 ·g -1 ), ultra-low density (as low as 3 mg·cm -3 ), large pore volume (several cm 3 ·g -1 ), low dielectric constant (approaching that of air), superior thermal-insulating behavior (< 0.015 W·m -1 ·K -1 ), outstanding sound-proofing property (> 100 kg·m -2 ·s -1 ), etc. [14,15]. In recent years, intensive studies and exploitations have been carried out across many fields including environmental remediation, thermal insulation, energy storage and conversion, detection, adsorption, catalysis, and so on [16][17][18]. From the perspective of chemistry, aerogels are the sol-gel derivatives made via supercritical fluid drying (or other special drying) of various gel precursors, while from the perspective of structure, aerogels are the of the building blocks play important roles in determining structure and function of the resulting aerogel monoliths [24]. In the case of aerogels assembled with spherical particles, the specific surface area is inversely proportional to both the diameter and density of the individual solid particles under the assumption of no surface overlapping of the particles as shown in Figure 1a. It is desirable to obtain large specific areas of the aerogel with small diameter and/or low density particles [25]. However, only a small range of diameters of the building blocks, from a few to several tens of nanom...

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supporting

confidence: 90%

Section: Thermoelectric Cellsmentioning

confidence: 99%

mentioning

confidence: 99%

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Assembling hollow carbon sphere-graphene polylithic aerogels for thermoelectric cells

Dong

Guo

et al. 2017

Nano Energy

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“…By exploiting the limiting current method, the mass transfer coefficient is estimated [7,18] from the Equation (1):…”

Section: Estimation Of Mass Transfer Coefficientmentioning

confidence: 99%

High Efficiency Graphene Coated Copper Based Thermocells Connected in Series

et al. 2018

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Conversion of low-grade waste heat into electricity had been studied employing single thermocell or flowcells so far. Graphene coated copper electrodes based thermocells connected in series displayed relatively high efficiency of thermal energy harvesting. The maximum power output of 49.2 W/m 2 for normalized cross sectional electrode area is obtained at 60 • C of inter electrode temperature difference. The relative carnot efficiency of 20.2% is obtained from the device. The importance of reducing the mass transfer and ion transfer resistance to improve the efficiency of the device is demonstrated. Degradation studies confirmed mild oxidation of copper foil due to corrosion caused by the electrolyte.

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“…For example, a maximum power density of 1.5 Wm -2 -electrode area with a Carnot efficiency of 1.4% was achieved in a TES operated with a ferrocyanide/ferricyanide redox solution and carbon nanotube electrodes when operated with a temperature difference of 60 °C [14]. The power density was increased to 6.6 W m -2 -electrode area (Carnot efficiency of 3.95%) using carbon nanotube aerogel sheets with a 51 °C temperature difference, but this required the use of platinum [15]. Even though this system could be viable due to the relatively high Carnot efficiencies [16], the systems still has a relatively low power density and it required the use of a precious metal.…”

Section: Introductionmentioning

confidence: 99%

Electrical power production from low-grade waste heat using a thermally regenerative ethylenediamine battery

Rahimi

D’Angelo

Gorski

et al. 2017

Journal of Power Sources

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Thermally regenerative ammonia-based batteries (TRABs) have been developed to harvest low-grade waste heat as electricity. To improve the power production and anodic coulombic efficiency, the use of ethylenediamine as an alternative ligand to ammonia was explored here. The power density of the ethylenediamine-based battery (TRENB) was 85 ± 3 Wm -2 electrode area with 2 M ethylenediamine, and 119 ±4 Wm -2 with 3 M ethylenediamine. This power density was 68% higher than that of TRAB. The energy density was 478 Whm -3 anolyte, which was ~50% higher than that produced by TRAB. The anodic coulombic efficiency of the TRENB was 77 ± 2%, which was more than twice that obtained using ammonia in a TRAB (35%). The higher anodic efficiency reduced the difference between the anode dissolution and cathode deposition rates, resulting in a process more suitable for closed loop operation. The thermal-electric efficiency based on ethylenediamine separation using waste heat was estimated to be 0.52%, which was lower than that of TRAB (0.86%), mainly due to the more complex separation process. However, this energy recovery could likely be improved through optimization of the ethylenediamine separation process.

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High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

Cited by 278 publications

References 34 publications

Assembling hollow carbon sphere-graphene polylithic aerogels for thermoelectric cells

Assembling hollow carbon sphere-graphene polylithic aerogels for thermoelectric cells

High Efficiency Graphene Coated Copper Based Thermocells Connected in Series

Electrical power production from low-grade waste heat using a thermally regenerative ethylenediamine battery

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