Thermogalvanic Potentials

Levin, Harry; Bonilla, C.F.

doi:10.1149/1.2778013

Cited by 12 publications

(9 citation statements)

References 7 publications

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“…The origin of this potential is analogous to that of potentials produced by thermocouples. A minor effect arises from the thermal diffusion potential, which is due to ion migration driven by the temperature difference in the electrolyte (Soret effect) 10, 20, 21. However, for most systems of interest, the electrode potentials dominate and the thermal diffusion potential can be neglected for practical purposes, since it is about three orders of magnitude lower than the electrode potential, making only negligible contribution to the total electromotive force (EMF) 14, 22…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Electrical Power From Nanotube and Graphene Electrochemical Thermal Energy Harvesters

Kang

Fang

Kozlov

et al. 2011

Adv Funct Materials

193

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Nanocarbon‐based thermocells involving aqueous potassium ferro/ferricyanide electrolyte are investigated as an alternative to conventional thermoelectrics for thermal energy harvesting. The dependencies of power output on thermocell parameters, such as cell orientation, electrode size, electrode spacing, electrolyte concentration and temperature, are examined to provide practical design elements and principles. Observation of thermocell discharge behavior provides an understanding of the three primary internal resistances (i.e., activation, ohmic and mass transport overpotentials). The power output from nanocarbon thermocells is found to be mainly limited by the ohmic resistance of the electrolyte and restrictions on mass transport in the porous nanocarbon electrode due to pore tortuosity. Based on these fundamental studies, a comparison of power generation is conducted using various nanocarbon electrodes, including purified single‐walled and multi‐walled carbon nanotubes (P‐SWNTs and P‐MWNTs, respectively), unpurified SWNTs, reduced graphene oxide (RGO) and P‐SWNT/RGO composite. The P‐SWNT thermocell has the highest specific power generation per electrode weight (6.8 W/kg for a temperature difference of 20 °C), which is comparable to that for the P‐MWNT electrode. The RGO thermocell electrode provides a substantially lower specific power generation (3.9 W/kg).

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Section: Theoretical Backgroundmentioning

confidence: 99%

“…An alternative conversion process utilizes an electrochemical pathway to provide thermogalvanic energy conversion 6, 10–16. A thermocell, also known as a thermogalvanic cell, is an electrochemical cell in which electrical energy is generated by the temperature difference between two half‐cells.…”

Section: Introductionmentioning

confidence: 99%

Electrical Power From Nanotube and Graphene Electrochemical Thermal Energy Harvesters

Kang

Fang

Kozlov

et al. 2011

Adv Funct Materials

193

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“…The resultant concentration gradient further changes the two electrode potentials, and the cell eventually reaches a new stationary state after thermal diffusion has become fully developed. However, most thermal cell 616 measurements have been conducted under experimental conditions unfavorable to the development of the Soret effect, and the initial state of the cell then has been found to be stable for extended periods of time (up to 24 hr) (13,30). Only the initial state of thermal cells is considered here.…”

Section: Thermal Temperature Coefficientsmentioning

confidence: 99%

“…The calculated value here seems to be about 0.05 mv/deg low. Silver chloride electrode.--For the silver chloride electrode: Ag + C1-----AgC1 + e-, V ~ --+0.2223 v, the entropy of electrochemical transport S% is S*% : S ~ (Ag) + S*%(CF) --S ~ (AgC1) = (10.206) + (13.2 + 4.48) --(22.97) = 4.92 cal/deg = 0.214 mvF/deg [29]Division by 1 faraday yields (dV~ C1-) = +0.214 mv/deg[30] This value may be compared with experiments of Tyrrell and Hollis (28) who deduce a value of +0.205 mv/deg for the standard thermal coefficient,…”

mentioning

confidence: 99%

The Temperature Coefficients of Electrode Potentials

deBethune

Licht

Swendeman

1959

J. Electrochem. Soc.

283

154

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The temperature coefficient of the potential of an electrode can be defined experimentally by reference to (a) the potential of the SHE at the same temperature, (b) the potential of the same electrode at some fixed temperature. These two definitions give rise to the "isothermal" and "thermal" temperature coefficients of electrode potentials. The isothermal coefficient is AS/nF where ~S is the reaction entropy of the "SHE//Electrode" cell. The thermal coefficient is S*/nF where S* is the entropy transported from the hot to the cold heat reservoir by the passage of n faradays of positive electricity through the cell from the cold to the hot electrode (before the onset of thermal diffusion). The entropy S* is divided into an entropy S*E of electrochemical transport which determines the electrode temperature effect, and an entropy S*. of migration transport which determines the thermal liquid junction potential.By assuming that S*~ is negligible in a saturated potassium chloride bridge, we have deduced that the thermal temperature coefficient of the SHE is +0.871 mv/~ [hot electrode (+) terminal] at 25~ The standard ionic entropy S* ~ of electrochemical transport of hydrogen ion is --4.48 cal/deg. Thermal temperature coefficients are computed for calomel, silver chloride, and copper sulfate electrodes and are compared with experiment. Thermal and isothermal temperature coefficients are computed and tabulated for nearly 300 standard electrode potentials.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.255.116 Downloaded on 2015-03-10 to IP Vol. 106, No. 7 COEFFICIENTS OF ELECTRODE POTENTIALS ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.255.116 Downloaded on 2015-03-10 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 132.174.255.116 Downloaded on 2015-03-10 to IP

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“…From this, they deduced values for other ions from the relation ~v~S~ = s + s [47] where S, is the conventional ionic entropy. Equation [47] is valid for any neutral ion combination for which ~v~S~ ~ ~v~S%, The final summation in [47] is, of course, S% for a neutral electrolyte. By taking S~ and S% data from various sources, Khor-~5 oshin and Temkin obtained the values of S , given in Table V.…”

Section: Values Of the Ionic Transport Entropiesmentioning

confidence: 99%

Irreversible Thermodynamics in Electrochemistry

deBethune

1960

J. Electrochem. Soc.

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The Onsager thermodynamics of irreversible processes provides a unified approach to the study of electrolytic systems out of equilibrium, such as concentration cells with transference, the initial and final emf's of thermal cells, and thermal diffusion (Soret effect) of ions. For concentration cells, the method justifies the classical results obtained by Nernst from equilibrium considerations. For nonisothermal systems, the product S*dT is the thermodynamic driving force of a process, where S* is the entropy transported reversibly from the "hot" to the "cold" heat reservoir (in the limiting case of equal temperatures) by the occurrence of a reversible process in the system. The emf of a concentration cell, the initial emf of a thermal cell, and the Soret coefficient, all properties of systems out of equilibrium, are determined, according to the Onsager relations, by the ratios of the reversible fluxes of matter to electricity, of entropy to electricity, and of entropy to matter, respectively, as they occur in systems completely at equilibrium.

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Thermogalvanic Potentials

Cited by 12 publications

References 7 publications

Electrical Power From Nanotube and Graphene Electrochemical Thermal Energy Harvesters

Electrical Power From Nanotube and Graphene Electrochemical Thermal Energy Harvesters

The Temperature Coefficients of Electrode Potentials

Irreversible Thermodynamics in Electrochemistry

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