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Floraki C, Androulidaki M, Spanakis E, Vernardou D. Effect of Electrolyte Concentration on the Electrochemical Performance of Spray Deposited LiFePO 4. Nanomaterials (Basel) 2023; 13:1850. [PMID: 37368280 DOI: 10.3390/nano13121850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 06/04/2023] [Accepted: 06/06/2023] [Indexed: 06/28/2023]
Abstract
LiFePO4 is a common electrode cathode material that still needs some improvements regarding its electronic conductivity and the synthesis process in order to be easily scalable. In this work, a simple, multiple-pass deposition technique was utilized in which the spray-gun was moved across the substrate creating a "wet film", in which-after thermal annealing at very mild temperatures (i.e., 65 °C)-a LiFePO4 cathode was formed on graphite. The growth of the LiFePO4 layer was confirmed via X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy. The layer was thick, consisting of agglomerated non-uniform flake-like particles with an average diameter of 1.5 to 3 μm. The cathode was tested in different LiOH concentrations of 0.5 M, 1 M, and 2 M, indicating an quasi-rectangular and nearly symmetric shape ascribed to non-faradaic charging processes, with the highest ion transfer for 2 M LiOH (i.e., 6.2 × 10-9 cm2/cm). Nevertheless, the 1 M aqueous LiOH electrolyte presented both satisfactory ion storage and stability. In particular, the diffusion coefficient was estimated to be 5.46 × 10-9 cm2/s, with 12 mAh/g and a 99% capacity retention rate after 100 cycles.
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Affiliation(s)
- Christina Floraki
- Department of Electrical and Computer Engineering, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
| | - Maria Androulidaki
- Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology Hellas (FORTH), 70013 Heraklion, Greece
| | - Emmanuel Spanakis
- Department of Materials Science and Technology, University of Crete, 70013 Heraklion, Greece
| | - Dimitra Vernardou
- Department of Electrical and Computer Engineering, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Greece
- Institute of Emerging Technologies, Hellenic Mediterranean University Center, 71410 Heraklion, Greece
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Ko TF, Chen PW, Li KM, Young HT. Applied IrO 2 Buffer Layer as a Great Promoter on Ti-Doping V 2O 5 Electrode to Enhance Electrochromic Device Properties. Materials (Basel) 2022; 15:5179. [PMID: 35897609 DOI: 10.3390/ma15155179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Revised: 07/18/2022] [Accepted: 07/19/2022] [Indexed: 11/16/2022]
Abstract
Electrochromic devices (ECDs) are a promising material for smart windows that are capable of transmittance variation. However, ECDs are still too expensive to achieve a wide market reach. Reducing fabrication cost remains a challenge. In this study, we inserted an IrO2 buffer layer on Ti-doped V2O5 (Ti:V2O5) as a counter electrode using various Ar/O2 gas flow ratios (1/2, 1/2.5, 1/3 and 1/3.5) in the fabrication process. The buffered-ECD resulted in a larger cyclic voltammetry (CV) area and the best surface average roughness (Ra = 3.91 nm) to promote electrochromic performance. It was fabricated using the low-cost, fast deposition process of vacuum cathodic arc plasma (CAP). This study investigates the influence of the IrO2 buffer/Ti:V2O5 electrode on ECD electrochemical and optical properties, in terms of color efficiency (CE) and cycle durability. The buffered ECD (glass/ITO/WO3/liquid electrolyte/IrO2 buffer/Ti:V2O5/ITO/glass) demonstrated excellent optical transmittance modulation; ∆T = 57% (from Tbleaching (67%) to Tcoloring (10%)) at 633 nm, which was higher than without the buffer (ITO/WO3/liquid electrolyte/Ti:V2O5/ITO) (∆T = 36%). In addition, by means of an IrO2 buffer, the ECD exhibited high coloration efficiency of 96.1 cm2/mC and good durability, which decayed by only 2% after 1000 cycles.
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Lin TC, Jheng BJ, Yen HM, Huang WC. Thermal Annealing Effects of V2O5 Thin Film as an Ionic Storage Layer for Electrochromic Application. Materials 2022; 15:ma15134598. [PMID: 35806721 PMCID: PMC9267838 DOI: 10.3390/ma15134598] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Revised: 06/25/2022] [Accepted: 06/27/2022] [Indexed: 02/06/2023]
Abstract
A vanadium pentoxide (V2O5) thin film with thermal annealing as an ionic storage layer for electrochromic devices is presented in our study. The V2O5 thin film was deposited on an ITO glass substrate by an RF magnetron sputtering. The electrochromic properties of the film were evaluated after various thermal annealing temperatures. The structural analysis of the film was observed by X-ray diffraction (XRD), field emission electron microscopy (FE-SEM), and atomic force microscopy (AFM). The structure of the V2O5 thin film transformed from an amorphous to polycrystalline structure with directions of (110) and (020) after 400 °C thermal annealing. The electrochromic properties of the film improved compared with the unannealed V2O5 thin film. We obtained a charge capacity of 97.9 mC/cm2 with a transparent difference ΔT value of 31% and coloration efficiency of 6.3 cm2/C after 400 °C thermal annealing. The improvement was due to the polycrystalline orthorhombic structure formation of V2O5 film by the rearrangement of atoms from thermal energy. Its laminate structure facilitates Li+ ion intercalation and increases charge capacity and transparent difference.
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Affiliation(s)
- Tien-Chai Lin
- Department of Electrical Engineering, Kun Shan University, Yongkang, Tainan 710303, Taiwan; (T.-C.L.); (B.-J.J.)
| | - Bai-Jhong Jheng
- Department of Electrical Engineering, Kun Shan University, Yongkang, Tainan 710303, Taiwan; (T.-C.L.); (B.-J.J.)
| | - Hui-Min Yen
- Green Energy Technology Research Center, Kun Shan University, Yongkang, Tainan 710303, Taiwan;
| | - Wen-Chang Huang
- Department of Electrical Engineering, Kun Shan University, Yongkang, Tainan 710303, Taiwan; (T.-C.L.); (B.-J.J.)
- Green Energy Technology Research Center, Kun Shan University, Yongkang, Tainan 710303, Taiwan;
- Correspondence:
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Mouratis K, Tudose IV, Romanitan C, Pachiu C, Popescu M, Simistiras G, Couris S, Suchea MP, Koudoumas E. WO3 Films Grown by Spray Pyrolysis for Smart Windows Applications. Coatings 2022; 12:545. [DOI: 10.3390/coatings12040545] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
WO3 nanostructured thin films were grown using spray deposition on FTO coated glass. The effect of the precursor concentration and the solution quantity, which determines the deposition time, on the electrochemical, electrochromic and optical properties of the WO3 films was investigated. The films were found to exhibit a good electrochromic activity with a reasonably good durability of charge exchange and optical modulation under harsh electrochemical cycling in Li-ion-conducting electrolyte. Associated compositional and structural characteristics were probed by several techniques, indicating that the observed improved durability may be due to the unique WO3 thin films’ structuring, the surface of the films consisting of wall-like structures combined with bubble-like islands on a polycrystalline WO3 granular background, that requires further study in greater detail.
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Mouratis K, Tudose IV, Bouranta A, Pachiu C, Romanitan C, Tutunaru O, Couris S, Koudoumas E, Suchea M. Annealing Effect on the Properties of Electrochromic V 2O 5 Thin Films Grown by Spray Deposition Technique. Nanomaterials (Basel) 2020; 10:nano10122397. [PMID: 33266196 PMCID: PMC7760595 DOI: 10.3390/nano10122397] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 11/25/2020] [Accepted: 11/27/2020] [Indexed: 11/16/2022]
Abstract
Nanostructured electrochromic V2O5 thin films were prepared using spray pyrolysis technique growth at a temperature of 250 °C using air-carrier spray deposition, starting from ammonium metavanadate precursor in water, followed by annealing at 400 °C in O2 atmosphere for 2 h. The V2O5 films were characterized by X-ray diffraction, scanning electron microscopy, and Raman spectroscopy, and their electrochromic behavior was studied using optical spectroscopy and cyclic voltammetry in both the as-deposited and postannealing case. The studies showed that the simple, cost -effective, suitable for large area deposition method used can lead to an interesting surface structuring with large active surface properties suitable for electrochromic applications. Further studies for growth optimization and improvements of films properties and stability are to be performed.
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Affiliation(s)
- Kyriakos Mouratis
- Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece; (K.M.); (I.V.T.); (A.B.)
- Department of Electrical and Computer Engineering, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece
- Physics Department, University of Patras, 26504 Patras, Greece;
| | - Ioan Valentin Tudose
- Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece; (K.M.); (I.V.T.); (A.B.)
- Chemistry Department, University of Crete, 70013 Heraklion, Greece
- Institute of Electronic Structure and Laser, Foundation for Research & Technology-Hellas, 70013 Heraklion, Crete, Greece
| | - Andrianna Bouranta
- Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece; (K.M.); (I.V.T.); (A.B.)
| | - Cristina Pachiu
- National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190 Voluntari-Bucharest, Romania; (C.P.); (C.R.); (O.T.)
| | - Cosmin Romanitan
- National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190 Voluntari-Bucharest, Romania; (C.P.); (C.R.); (O.T.)
| | - Oana Tutunaru
- National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190 Voluntari-Bucharest, Romania; (C.P.); (C.R.); (O.T.)
| | - Stelios Couris
- Physics Department, University of Patras, 26504 Patras, Greece;
| | - Emmanouel Koudoumas
- Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece; (K.M.); (I.V.T.); (A.B.)
- Department of Electrical and Computer Engineering, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece
- Correspondence: (E.K.); or (M.S.)
| | - Mirela Suchea
- Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 71410 Heraklion, Crete, Greece; (K.M.); (I.V.T.); (A.B.)
- National Institute for Research and Development in Microtechnologies-IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190 Voluntari-Bucharest, Romania; (C.P.); (C.R.); (O.T.)
- Correspondence: (E.K.); or (M.S.)
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Abstract
Pursuing a scalable production methodology for materials and advancing it from the laboratory to industry is beneficial to novel daily-life applications. From this perspective, chemical vapor deposition (CVD) offers a compromise between efficiency, controllability, tunability and excellent run-to-run repeatability in the coverage of monolayer on substrates. Hence, CVD meets all the requirements for industrialization in basically everything including polymer coatings, metals, water-filtration systems, solar cells and so on. The Special Issue “Advances in Chemical Vapor Deposition” has been dedicated to giving an overview of the latest experimental findings and identifying the growth parameters and characteristics of perovskites, TiO2, Al2O3, VO2 and V2O5 with desired qualities for potentially useful devices.
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Affiliation(s)
- Dimitra Vernardou
- Department of Electrical and Computer Engineering, School of Engineering, Hellenic Mediterranean University, 710 04 Heraklion, Greece; ; Tel.: +30-2810-379631
- Center of Materials Technology and Photonics, School of Engineering, Hellenic Mediterranean University, 710 04 Heraklion, Greece
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