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Inoue H, Zhou H, Ando H, Nakagawa S, Yamada T. Exploring the local solvation structure of redox molecules in a mixed solvent for increasing the Seebeck coefficient of thermocells. Chem Sci 2023; 15:146-153. [PMID: 38131095 PMCID: PMC10732003 DOI: 10.1039/d3sc04955h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 11/24/2023] [Indexed: 12/23/2023] Open
Abstract
A thermocell is an emerging alternative to thermoelectric devices and exhibits a high Seebeck coefficient (Se) due to the large change of solvation entropy associated with redox reactions. Here, the Se of p-chloranil radicals/dianions (CA˙-/2-) in acetonitrile was drastically increased from -1.3 to -2.6 mV K-1 by the addition of ethanol, and the increment surpassed the estimation of the classical Born model with continuum solvent media. UV-vis spectroscopy and electrochemical measurements at various mixing ratios of acetonitrile to ethanol revealed that the strong hydrogen bonding between ethanol and oxygen atoms of CA2- forms a 4 : 1 solvent-ion pair, while the ethanol molecules binding to CA2- dissociate upon its oxidation to CA˙-. The local solvation structures of CA2- are in good agreement with density functional theory. This order-disorder transition of the local solvation structure around the CA˙-/2- ions produces a large entropy change and results in a large Se value. The tailored solvation structure of redox ions by hydrogen bonding is a versatile method applicable to a variety of redox pairs and solvents, contributing to the development of electrolyte engineering for thermocells.
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Affiliation(s)
- Hirotaka Inoue
- Department of Chemistry, Graduate School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Hongyao Zhou
- Department of Chemistry, Graduate School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
| | - Hideo Ando
- Faculty of Science, Yamagata University 1-4-12 Kojirakawa-machi Yamagata 990-8560 Japan
| | - Sakuya Nakagawa
- Faculty of Science, Yamagata University 1-4-12 Kojirakawa-machi Yamagata 990-8560 Japan
| | - Teppei Yamada
- Department of Chemistry, Graduate School of Science, The University of Tokyo 7-3-1 Hongo, Bunkyo-ku Tokyo 113-0033 Japan
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Zong Y, Chen L, Li X, Ding Q, Han W, Lou J. Highly robust and sensitive dual-network freeze-resistant organic hydrogel thermocells. Carbohydr Polym 2023; 314:120958. [PMID: 37173052 DOI: 10.1016/j.carbpol.2023.120958] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 04/18/2023] [Accepted: 04/23/2023] [Indexed: 05/15/2023]
Abstract
Thermocells (TECs) are eco-friendly and ideal power-generation devices that sustainably convert waste heat into electricity to power wearable electronics. However, their poor mechanical properties, limited operating temperature, and low sensitivity limit their practical application. Hence, K3/4Fe(CN)6 and NaCl thermoelectric materials were introduced into a bacterial cellulose-reinforced polyacrylic acid double-network structure and permeated into a glycerol (Gly)/water binary solvent to prepare an organic thermoelectric hydrogel. The resulting hydrogel had a tensile strength of approximately 0.9 MPa and a stretched length of approximately 410 %; moreover, it worked stably even in the stretched/twisted state. Owing to the introduction of Gly and NaCl, the as-prepared hydrogel exhibited excellent freezing tolerance (- 22 °C). In addition, the TEC also demonstrated excellent sensitivity (~13 s). Good environmental stability and high sensitivity make this hydrogel TEC a promising candidate for thermoelectric power-generation/temperature-monitoring systems.
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Affiliation(s)
- Yudong Zong
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China
| | - Luzheng Chen
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China
| | - Xia Li
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China
| | - Qijun Ding
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China
| | - Wenjia Han
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China
| | - Jiang Lou
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China.
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Laws K, Buckingham MA, Farleigh M, Ma M, Aldous L. High Seebeck coefficient thermogalvanic cells via the solvent-sensitive charge additivity of cobalt 1,8-diaminosarcophagine. Chem Commun (Camb) 2023; 59:2323-2326. [PMID: 36752070 DOI: 10.1039/d2cc05413b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Thermogalvanic devices can chemically convert low grade (<200 °C) waste thermal energy into electrical energy. A temperature gradient across the device drives an entropically favourable electrochemical redox reaction, resulting in continuous current production. The voltage correlates with the entropy change during the redox reaction, which favours high valence metal complexes with high charge densities. Here we investigate cobalt (II/III) sarcophagine ([Co(SAR)]2+/3+) for application in thermogalvanic cells, as a function of solvent; the two uncoordinated amine groups 1,8-diaminosarcophagine are typically protonated to form tetracationic/pentacationic [Co(SARH2)]4+/5+. In water, [Co(SARH2)]4+/5+ gave a thermogalvanic Seebeck coefficient (Se) of +0.43 mV K-1, which is entropically consistent with just the Co2+/3+ core valence, whereas DMSO and ionic liquid solvents gave Se values of +1.84 and +2.04 mV K-1, respectively, in line with the 'Co4+/5+' overall complex. This work proves how the ionic charge on pendant moieties can undergo charge-additivity with the metal core to significantly boost entropically-driven processes, but only in suitably low dielectric and bulky solvents.
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Affiliation(s)
- Kristine Laws
- Department of Chemistry, King's College London, London, SE1 1DB, UK.
| | - Mark A Buckingham
- Department of Chemistry, King's College London, London, SE1 1DB, UK.
| | - Matthew Farleigh
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, SE1 7EH, UK
| | - Michelle Ma
- School of Biomedical Engineering and Imaging Sciences, King's College London, St. Thomas' Hospital, London, SE1 7EH, UK
| | - Leigh Aldous
- Department of Chemistry, King's College London, London, SE1 1DB, UK.
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Zhou H, Inoue H, Ujita M, Yamada T. Advancement of Electrochemical Thermoelectric Conversion with Molecular Technology. Angew Chem Int Ed Engl 2023; 62:e202213449. [PMID: 36239979 DOI: 10.1002/anie.202213449] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Indexed: 11/24/2022]
Abstract
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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Affiliation(s)
- Hongyao Zhou
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Hirotaka Inoue
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Mizuha Ujita
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Teppei Yamada
- Department of Chemistry, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
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Matsui Y, Kawase M, Suzuki T, Tsushima S. Electrochemical cell recharging by solvent separation and transfer processes. Sci Rep 2022; 12:3739. [PMID: 35260617 PMCID: PMC8904837 DOI: 10.1038/s41598-022-07573-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 02/21/2022] [Indexed: 12/01/2022] Open
Abstract
Electrochemical conversion and storage of unutilized renewable energy will contribute to decarbonization. Here, we create the concept of a liquid electrochemical cell that discharges between the anodic and cathodic sides by reverse reactions of the same redox couple in different solvation states, which are created by differences in the mixture ratios of two solvents called the main solvent (MS) and the transferred solvent (TS). The cell can be charged by a transfer of the TS between the discharged anolyte and catholyte. As an example, we demonstrate a cell utilizing a ferro-/ferricyanide redox couple. Stable discharging and charging via the proposed method is achieved by utilizing water (MS) and acetone (TS). Additionally, dominating factors in the design of a high-performance system are discussed, focusing on the electron acceptability of the MS and the TS. The cell voltages are successfully tuned, and a cell voltage of 0.63 V is achieved by the combination of dimethyl sulfoxide (MS) and water (TS). Moreover, the cell can be customized by various electrochemical reaction systems, which can allow multiple options for the charging processes. This concept provides new approaches for the utilization of diverse energy sources as an input for the charging of electrochemical cells.
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Affiliation(s)
- Yohei Matsui
- Energy Chemistry Division, Energy Transformation Research Laboratory, Central Research Institute of Electric Power Industry, Yokosuka, 240-0196, Japan. .,Department of Mechanical Engineering, Graduate School of Engineering, Osaka University, Suita, 565-0871, Japan.
| | - Makoto Kawase
- Energy Chemistry Division, Energy Transformation Research Laboratory, Central Research Institute of Electric Power Industry, Yokosuka, 240-0196, Japan
| | - Takahiro Suzuki
- Department of Mechanical Engineering, Graduate School of Engineering, Osaka University, Suita, 565-0871, Japan
| | - Shohji Tsushima
- Department of Mechanical Engineering, Graduate School of Engineering, Osaka University, Suita, 565-0871, Japan
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Investigation of iron(III) ionic structural complexes for seebeck coefficient enhancement using variation of ligand lengths with extended Π-conjugated bipyridyl ligands. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.130202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Li M, Hong M, Dargusch M, Zou J, Chen ZG. High-efficiency thermocells driven by thermo-electrochemical processes. TRENDS IN CHEMISTRY 2021. [DOI: 10.1016/j.trechm.2020.11.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Inoue H, Liang Y, Yamada T, Kimizuka N. Enhanced Seebeck coefficients of thermocells by heat-induced deposition of I 3-/hydrophobized α-cyclodextrin complexes on electrodes. Chem Commun (Camb) 2020; 56:7013-7016. [PMID: 32441729 DOI: 10.1039/d0cc02356f] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Ethylated α-cyclodextrin (Et18-α-CD) is used as a host matrix for I-/I3- thermocells. Although Et18-α-CD is not soluble in water at ambient temperature, it becomes soluble by complexation of the I3- anion. Meanwhile, the complex is precipitated upon elevating the temperature. The change in thermo-responsive solubility of the I3-/Et18-α-CD complex increases the Seebeck coefficient (Se) of the thermocell up to 2.6 mV K-1. The underlying mechanism of the increased Se is elucidated by UV-vis spectroscopy, Raman spectroscopy, and electrochemical measurements. This result shows the temperature-dependent solubility changes of redox-active species as a potential means to improve the performance of electrochemical thermocells.
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Affiliation(s)
- Hirotaka Inoue
- Division of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Motooka 744, Nishi-ku, Fukuoka 819-0395, Japan.
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