A Novel Thermocell System Using Proton Solvation Entropy

Kobayashi, Takashi; Yamada, Teppei; Tadokoro, Makoto; Kimizuka, Nobuo

doi:10.1002/chem.202004562

Cited by 10 publications

(21 citation statements)

References 31 publications

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“…Complex 2 had already been used in a new thermo-electrochemical cell exploiting both protons and electrons. [18] As revealed by X-ray crystal structure analysis, the crystal of 1 has a high-symmetry crystal structure with a cubic Pa3 ̄(#205) space group constructed from two chiral intermolecular Hbonding networks through twofold interpenetration. The chiral networks are formed by complementary NÀ H•••N H-bonding between HIm and Im À groups.…”

Section: Resultsmentioning

confidence: 99%

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Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of Ru^III Complexes with Six Imidazole‐Imidazolate Ligands

Tadokoro

Itoh

Nishimura

et al. 2022

Chemistry A European J

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A new H-bonded crystal [Ru III (Him) 3 (Im) 3 ] with three imidazole (Him) and three imidazolate (Im À ) groups was prepared to obtain a higher-temperature proton conductor than a Nafion membrane with water driving. The crystal is constructed by complementary NÀ H•••N H-bonds between the Ru III complexes and has a rare Icy-c* cubic network topology with a twofold interpenetration without crystal anisotropy. The crystals show a proton conductivity of 3.08 × 10 À 5 S cm À 1 at 450 K and a faster conductivity than those formed by only HIms. The high proton conductivity is attributed to not only molecular rotations and hopping motions of HIm frameworks that are activated at ~113 K, but also isotropic wholemolecule rotation of [Ru III (Him) 3 (Im) 3 ] at temperatures greater than 420 K. The latter rotation was confirmed by solid-state 2 H NMR spectroscopy; probable proton conduction routes were predicted and theoretically considered.

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Section: Resultsmentioning

confidence: 99%

“…Interestingly, the redox reaction involving the transfer of only one electron can also transfer more than three protons in strongly basic conditions. Complex 2 had already been used in a new thermo‐electrochemical cell exploiting both protons and electrons [18] …”

Section: Resultsmentioning

confidence: 99%

Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of Ru^III Complexes with Six Imidazole‐Imidazolate Ligands

Tadokoro

Itoh

Nishimura

et al. 2022

Chemistry A European J

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“…Conventionally, research on thermocells has focused on finding the best combination of redox pairs and solvents to increase the redox entropy, but most of the S e values obtained using this strategy fall below 2 mV K −1 . To overcome this limit, a new strategy using the PCET of a Ru complex resulted in a high S e value (−3.7 mV K −1 ) [43] …”

Section: Discussionmentioning

confidence: 99%

“…The S e value of the thermocell is proportional to its Δ S value before and after the redox reaction (Δ S rc ). Δ S rc can be induced by various factors, such as spin transitions, [11] change of the solvation structure, [40] formation or breakage of polyanionic chains (such as polyiodide and polysulfide), [41, 42] and protonation or deprotonation of the redox species [43] …”

Section: Redox Entropymentioning

confidence: 99%

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Advancement of Electrochemical Thermoelectric Conversion with Molecular Technology

et al. 2022

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Thermocells are a thermoelectric conversion technology that utilizes the shift in an electrochemical equilibrium arising from a temperature difference. This technology has a long history; however, its low conversion efficiency impedes its practical usage. Recently, an increasing number of reports have shown drastic improvements in thermoelectric conversion efficiency, and thermocells could arguably represent an alternative to solid thermoelectric devices. In this Minireview, we regard thermocells as molecular systems consisting of successive molecular processes responding to a temperature change to achieve energy generation. Various molecular technologies have been applied to thermocells in recent years, and could stimulate diverse research fields, including supramolecular chemistry, physical chemistry, electrochemistry, and solid-state ionics. These research approaches will also provide novel methods for achieving a sustainable society in the future.

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Direct Conversion of Phase‐Transition Entropy into Electrochemical Thermopower and the Peltier Effect

et al. 2023

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A thermocell generates thermopower from a temperature difference (ΔT) between two electrodes. The converse process of thermocells is an electrochemical Peltier effect, which creates a ΔT on the electrodes by applying an external current. The Seebeck coefficient (Se) of the electrochemical system is proportional to the entropy change of the redox reaction; therefore, a redox system having a significant entropy change is expected to increase the Se. In this study, a thermoresponsive polymer having a redox‐active moiety, poly(N‐isopropyl acrylamide‐co‐N‐(2‐acrylamide ethyl)‐N′‐n‐propylviologen) (PNV), is used as the redox species of a thermocell. PNV2+ dication undergoes the coil–globule phase transition upon the reduction to PNV+ cation radical, and a large entropy change is introduced because water molecules are freed from the polymer chains. The Se of PNV thermocell drastically increased to +2.1 mV K−1 at the lower critical solution temperature (LCST) of PNV. The entropy change calculated from the increment of Se agrees with the value evaluated by differential scanning calorimetry. Moreover, the electrochemical Peltier effect is observed when the device temperature is increased above the LCST. This study shows that the large entropy change associated with the coil–globule phase transition can be used in electrochemical thermal management and refrigeration technologies.

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A Novel Thermocell System Using Proton Solvation Entropy

Cited by 10 publications

References 31 publications

Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of Ru^III Complexes with Six Imidazole‐Imidazolate Ligands

Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of Ru^III Complexes with Six Imidazole‐Imidazolate Ligands

Advancement of Electrochemical Thermoelectric Conversion with Molecular Technology

Direct Conversion of Phase‐Transition Entropy into Electrochemical Thermopower and the Peltier Effect

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A Novel Thermocell System Using Proton Solvation Entropy

Cited by 10 publications

References 31 publications

Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of RuIII Complexes with Six Imidazole‐Imidazolate Ligands

Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of RuIII Complexes with Six Imidazole‐Imidazolate Ligands

Advancement of Electrochemical Thermoelectric Conversion with Molecular Technology

Direct Conversion of Phase‐Transition Entropy into Electrochemical Thermopower and the Peltier Effect

Contact Info

Product

Resources

About

Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of Ru^III Complexes with Six Imidazole‐Imidazolate Ligands

Proton Conduction at High Temperature in High‐Symmetry Hydrogen‐Bonded Molecular Crystals of Ru^III Complexes with Six Imidazole‐Imidazolate Ligands