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Chai Y, Matsushita S. Preparation and Evaluation of PVDF-HFP-Based Gel Electrolyte for Ge-Sensitized Thermal Cell. Polymers (Basel) 2024; 16:1732. [PMID: 38932082 PMCID: PMC11207463 DOI: 10.3390/polym16121732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/06/2024] [Accepted: 06/11/2024] [Indexed: 06/28/2024] Open
Abstract
The semiconductor-sensitized thermal cell (STC) is a new thermoelectric conversion technology. The development of nonliquid electrolytes is the top priority for the practical application of the STC. In this study, a novel gel polymer electrolyte (PH-based GPE) composed of poly(vinylidenefluoride-co-hexafluoropropylene) (PH), 1-Methyl-2-pyrrolidone (NMP), and Cu ions was synthesized and applied to the STC system. The PH-based GPE synthesized at 45 °C showed higher open-circuit voltage (-0.3 V), short-circuit current density (59 μA cm-2) and diffusion coefficient (7.82 × 10-12 m2 s-1), indicating that a well-balanced structure among the NMP molecules was formed to generate a high-efficiency conduction path of the Cu ions. Moreover, the ion diffusion lengths decreased with decreasing content rates of NMP for the PH-based GPEs, indicating that the NMP plays an important role in the diffusion of Cu ions. Furthermore, the activation energy was calculated to be 107 kJ mol-1, and that was smaller compared to 150 kJ mol-1 for the poly(ethylene glycol)-based liquid electrolyte. These results play an important reference role in the development of electrolytes for STC systems. At the same time, they also provide a new avenue and reference indicator for the synthesis of high-performance and safe GPEs.
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Affiliation(s)
- Yadong Chai
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Kanagawa, Japan;
| | - Sachiko Matsushita
- Department of Materials Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Kanagawa, Japan;
- elleThermo, Ltd., 3-3-6 Shibaura, Minato-ku, Tokyo 108-0023, Japan
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Solvent Evaporation Rate as a Tool for Tuning the Performance of a Solid Polymer Electrolyte Gas Sensor. Polymers (Basel) 2022; 14:polym14214758. [DOI: 10.3390/polym14214758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/02/2022] [Accepted: 11/04/2022] [Indexed: 11/09/2022] Open
Abstract
Solid polymer electrolytes show their potential to partially replace conventional electrolytes in electrochemical devices. The solvent evaporation rate represents one of many options for modifying the electrode–electrolyte interface by affecting the structural and electrical properties of polymer electrolytes used in batteries. This paper evaluates the effect of solvent evaporation during the preparation of solid polymer electrolytes on the overall performance of an amperometric gas sensor. A mixture of the polymer host, solvent and an ionic liquid was thermally treated under different evaporation rates to prepare four polymer electrolytes. A carbon nanotube-based working electrode deposited by spray-coating the polymer electrolyte layer allowed the preparation of the electrode–electrolyte interface with different morphologies, which were then investigated using scanning electron microscopy and Raman spectroscopy. All prepared sensors were exposed to nitrogen dioxide concentration of 0–10 ppm, and the current responses and their fluctuations were analyzed. Electrochemical impedance spectroscopy was used to describe the sensor with an equivalent electric circuit. Experimental results showed that a higher solvent evaporation rate leads to lower sensor sensitivity, affects associated parameters (such as the detection/quantification limit) and increases the limit of the maximum current flowing through the sensor, while the other properties (hysteresis, repeatability, response time, recovery time) change insignificantly.
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Sedlak P, Sobola D, Gajdos A, Dallaev R, Nebojsa A, Kubersky P. Surface Analyses of PVDF/NMP/[EMIM][TFSI] Solid Polymer Electrolyte. Polymers (Basel) 2021; 13:polym13162678. [PMID: 34451218 PMCID: PMC8401855 DOI: 10.3390/polym13162678] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/05/2021] [Accepted: 08/09/2021] [Indexed: 11/17/2022] Open
Abstract
Thermal treatment conditions of solid polymer polymer electrolyte (SPE) were studied with respect to their impact on the surface morphology, phase composition and chemical composition of an imidazolium ionic-liquid-based SPE, namely PVDF/NMP/[EMIM][TFSI] electrolyte. These investigations were done using scanning electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry as well as X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. A thoroughly mixed blend of polymer matrix, ionic liquid and solvent was deposited on a ceramic substrate and was kept at a certain temperature for a specific time in order to achieve varying crystallinity. The morphology of all the electrolytes consists of spherulites whose average diameter increases with solvent evaporation rate. Raman mapping shows that these spherulites have a semicrystalline structure and the area between them is an amorphous region. Analysis of FTIR spectra as well as Raman spectroscopy showed that the β-phase becomes dominant over other phases, while DSC technique indicated decrease of crystallinity as the solvent evaporation rate increases. XPS and ToF-SIMS indicated that the chemical composition of the surface of the SPE samples with the highest solvent evaporation rate approaches the composition of the ionic liquid.
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Affiliation(s)
- Petr Sedlak
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technicka 10, 616 00 Brno, Czech Republic; (D.S.); (A.G.); (R.D.)
- Correspondence: ; Tel.: +420-54114-6021
| | - Dinara Sobola
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technicka 10, 616 00 Brno, Czech Republic; (D.S.); (A.G.); (R.D.)
- Institute of Physics of Materials, Academy of Sciences CR, Zizkova 22, 616 62 Brno, Czech Republic
| | - Adam Gajdos
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technicka 10, 616 00 Brno, Czech Republic; (D.S.); (A.G.); (R.D.)
| | - Rashid Dallaev
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technicka 10, 616 00 Brno, Czech Republic; (D.S.); (A.G.); (R.D.)
| | - Alois Nebojsa
- Central European Institute of Technology (CEITEC), Brno University of Technology, Purkynova 123, 612 00 Brno, Czech Republic;
| | - Petr Kubersky
- Research and Innovation Centre for Electrical Engineering (RICE), Faculty of Electrical Engineering, University of West Bohemia, Univerzitni 8, 301 00 Plzen, Czech Republic;
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Veena G, Lobo B. Microstructural features, spectroscopic study and thermal analysis of potassium permanganate filled PVA-PVP blend films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:255101. [PMID: 33849000 DOI: 10.1088/1361-648x/abf785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
Potassium permanganate (KMnO4) filled polyvinyl alcohol (PVA)-polyvinylpyrrolidone (PVP) polymeric blend films have been prepared by solution casting technique, with filler levels (FL) varying from 0.01 up to 4.70 mass%. The microstructural features, thermal properties and spectroscopic properties of these films have been studied using powder XRD, AFM, Fe-SEM, DSC, TG and FTIR. FTIR spectra for filled samples indicated a major molecular structural modification, involving conversion of the hydroxyl (OH) group into ketones at higher FLs. The bands showed a clear distortion in the wide OH band especially at higher FLs of 3.80 mass% and 4.70 mass%. This is confirmed from the TG scans, whose thermal degradation signature reveals multiple stages of degradation for FL of 2.8 mass%, 3.8 mass% and 4.7 mass%. The DSC, TG and DTA curves revealed that value ofTgwas found to decrease on addition of filler in the PVA-PVP blend, whereas the thermal stability of the filled samples was found to increase. The XRD results revealed that the incorporation of KMnO4in PVA-PVP blend made the sample more amorphous. At low FLs, AFM and SEM micrographs show evidence for formation of nano-particles in the host polymeric material only at the lowest FL of 0.01 mass% with uniform dispersion of nano-structures, whereas at moderate FLs, there are micro-structures in the polymeric host, followed by agglomeration of filler induced chemical species as the FL increases beyond 2.8 mass%. Therefore, KMnO4filled PVA-PVP blend films show desirable properties expected from a good solid polymeric electrolyte, for FLs below 1.5 mass%.
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Affiliation(s)
- G Veena
- Department of Physics, Karnatak University's Karnatak Science College, Dharwad, Karnataka 580001, India
| | - Blaise Lobo
- Department of Physics, Karnatak University's Karnatak Science College, Dharwad, Karnataka 580001, India
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Sedlak P, Gajdos A, Macku R, Majzner J, Holcman V, Sedlakova V, Kubersky P. The effect of thermal treatment on ac/dc conductivity and current fluctuations of PVDF/NMP/[EMIM][TFSI] solid polymer electrolyte. Sci Rep 2020; 10:21140. [PMID: 33273700 PMCID: PMC7713362 DOI: 10.1038/s41598-020-78363-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 11/23/2020] [Indexed: 11/09/2022] Open
Abstract
The experimental study deals with the investigation of the effect of diverse crystallinity of imidazolium ionic-liquid-based SPE on conductivity and current fluctuations. The experimental study was carried out on samples consisting of [EMIM][TFSI] as ionic liquid, PVDF as a polymer matrix and NMP as a solvent. After the deposition, the particular sample was kept at an appropriate temperature for a specific time in order to achieve different crystalline forms of the polymer in the solvent, since the solvent evaporation rate controls crystallization. The ac/dc conductivities of SPEs were investigated across a range of temperatures using broadband dielectric spectroscopy in terms of electrical conductivity. In SPE samples of the higher solvent evaporation rate, the real parts of conductivity spectra exhibit a sharper transition during sample cooling and an increase of overall conductivity, which is implied by a growing fraction of the amorphous phase in the polymer matrix in which the ionic liquid is immobilized. The conductivity master curves illustrate that the changing of SPEs morphology is reflected in the low frequency regions governed by the electrode polarization effect. The dc conductivity of SPEs exhibits Vogel–Fulcher–Tammann temperature dependence and increases with the intensity of thermal treatment. Spectral densities of current fluctuations showed that flicker noise, thermal noise and shot noise seems to be major noise sources in all samples. The increase of electrolyte conductivity causes a decrease in bulk resistance and partially a decrease in charge transfer resistance, while also resulting in an increase in shot noise. However, the change of electrode material results in a more significant change of spectral density of current fluctuations than the modification of the preparation condition of the solid polymer electrolyte. Thus, the contact noise is considered to contribute to overall current fluctuations across the samples.
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Affiliation(s)
- Petr Sedlak
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 10, Brno, 616 00, Czech Republic.
| | - Adam Gajdos
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 10, Brno, 616 00, Czech Republic
| | - Robert Macku
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 10, Brno, 616 00, Czech Republic
| | - Jiri Majzner
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 10, Brno, 616 00, Czech Republic
| | - Vladimir Holcman
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 10, Brno, 616 00, Czech Republic
| | - Vlasta Sedlakova
- Faculty of Electrical Engineering and Communications, Brno University of Technology, Technická 10, Brno, 616 00, Czech Republic
| | - Petr Kubersky
- Faculty of Electrical Engineering, Regional Innovation Centre for Electric Engineering, University of West Bohemia, Univerzitni 8, Plzen, 301 00, Czech Republic
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