Polymer electrolytes for electrochromic devices

Polymer electrolytes are currently the focus of much attention as potential electrolytes in electrochemical devices such as batteries, display devices and sensors. Generically, solid polymer electrolytes (SPEs) are mixtures of salts with soft polar polymers. SPEs have many advantages including high energy density, no risk of leakage, no issues related to the presence of solvent, wide electrochemical stability windows, simplified processability and light weight. With the goal of developing a new family of environmentally friendly multifunctional biohybrid materials displaying high ionic conductivity we have produced in the present work, flexible films based on different polymers or hybrids incorporating different salts. The polymer electrolytes studied here have been characterized by means of Differential Scanning Calorimetry, Thermogravimetric Analysis, X-ray diffraction, Polarized Optical Microscopy, complex impedance spectroscopy and cyclic voltammetry. An evaluation of the performance of the sample with the highest conductivity as electrolyte in all solid-state ECDs was performed

Electrochromic device composed of a Di-Urethanesil electrolyte incorporating lithium triflate and 1-Butyl-3-Methylimidazolium chloride

A di-urethane cross-linked poly(oxyethylene)/silica hybrid matrix [di-urethanesil, d-Ut(600)], synthesized by the sol-gel process, was doped with lithium triflate (LiCF3SO3) and the 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid. The as-produced xerogel film is amorphous, transparent, flexible, homogeneous, hydrophilic, and has low nanoscale surface roughness. It exhibits an ionic conductivity of 3.64 x 10(-6) and 5.00 x 10(-4) S cm(-1) at 21 and 100 degrees C, respectively. This material was successfully tested as electrolyte in an electrochromic device (ECD) with the glass/ITO/a-WO3/d-Ut(600)(10)LiCF3SO3[Bmim]Cl/c-NiO/ITO/glass configuration, where a-WO3 and c-NiO stand for amorphous tungsten oxide and crystalline nickel oxide, respectively. The device demonstrated attractive electro-optical performance: fast response times (1-2 s for coloring and 50 s for bleaching), good optical memory [loss of transmittance (T) of only 41% after 3 months, at 555 nm], four mode modulation [bright mode (+3.0 V, T = 77% at 555 nm), semi-bright mode (-1.0 V, T = 60% at 555 nm), dark mode (-1.5 V, T = 38 % at 555 nm), and very dark mode (-2.0 V, T = 11% and -2.5 V, T = 7% at 555 nm)], excellent cycling stability denoting improvement with time, and high coloration efficiency [CEin = -6727 cm(2) C-1 (32th cycle) and CEout = +2794 cm(2) C-1 (480th cycle), at 555 nm].The authors are grateful to Fundacao para a Ciencia e a Tecnologia (FCT) and when applicable by FEDER under the PT2020 Partnership Agreement for financial support under contracts PEst-OE/SAU/UI0709/2014, UID/Multi/00709/2013, UID/QUI/00686/2016, UID/QUI/00686/2018, UID/QUI/00686/2019, PEst-OE/QUI/UI0616/2016, FCOMP-01-0124-FEDER037271, UID/CTM/50011/2013, LUMECD project (POCI01-0145-FEDER-016884 and PTDC/CTM-NAN/0956/2014), UniRCell project (SAICTPAC/0032/2015 and POCI-01-0145FEDER-016422). RP and SN acknowledge FCT-MCTES for grants (SFRH/BPD/87759/2012 and LUMECD, respectively). RP thanks FCT-UM for the contracts in the scope of Decreto-Lei 57/2016 and 57/2017. MF acknowledges FCTUTAD for the contract in the scope of Decreto-Lei 57/2016 -Lei 57/2017. HG acknowledges projects POCI-010145-FEDER-030858 and PTDC/BTM-MAT/30858/2017 for financial support

Ionic conductivity biomembranes for application in opto-electronics

Tese de Doutoramento em Ciências (Especialidade em Química)Polymer electrolytes (PEs) are ionically conducting materials that appeared as a good alternative to replace the traditional liquid ones. To prepare a PE, one host polymer is required to acting as a base matrix, and over the years, many polymers have been used. Natural polymers appeared as alternative of synthetic ones and chitosan has been largely investigated due to its high availability and its interesting properties. Ion conducting polymers are key materials for developing commercial devices and so the ionic conductivity is a very important parameter of an electrolyte. Thus, various approaches have been made to enhance the ionic conductivity including plasticization, addition of salts, mixed salt, and blend of polymers. The influence of the different lanthanide salts in the chitosan matrix was evaluated. The salt concentration influences the ionic conductivity and the optimum salt amount varies depending on the lanthanide used. For the samples with 0.05 g of salt, the electrolyte with cerium triflate presented the highest conductivity values of 9.25×10-7 S cm-1 at 30ºC. In the case of the samples with 0.15 and 0.25 g of lanthanide salts, the ionic conductivity increased and reached maximum values of 9.18×10-7 S cm-1 and 1.52×10-6 S cm-1, respectively, for the samples with europium triflate at 30ºC. The photoluminescent properties of solid polymer electrolytes based on chitosan and europium triflate were evaluated, and these studies indicated the characteristic emission and excitation transitions of Eu3+. The presence of a single peak for the 5D0→7F0 transition is an indication that europium ions occupied a single, low symmetry site in the polymeric host, which was also corroborated by the intense emission at 615 nm (5D0→7F2 transition). In biohybrid electrolyte doped with LiCF3SO3 and Eu(CF3SO3)3 the ionic conductivity values in the range 5.38×10-6 (30ºC) to 8.77×10-5 (80ºC) S cm-1 were obtained, which are higher than those of analogous polymer electrolytes singly doped with EuIII salts, and very similar to those doped with lithium salts. In a binary system of two salts: cerium and lithium triflates, the best ionic conductivity, 10-6 S cm-1 (at 30ºC), was obtained for the samples with 0.15 g of total salt amount. In the case of the chitosan materials containing different glycerol amounts an increase in glycerol amount promotes an increase of ionic conductivity by 1 or 2 orders of magnitude, and thus these samples were chosen to assemble small electrochromic devices. The ECDs with WO3 electrochromic layer (CHLnTrifxGly0.70, for LnTrifx = CeTrif0.10, DyTrif0.15, and SmTrif0.05) are almost transparent just after assembling, and after the negative potential application, the devices changed from almost transparent to blue color. This change in color is associated with WO3 reduction and simultaneous positive ion insertion, while the application of inverse potential promotes a return of the device to its initial state, as a result of WO3 oxidation and cation disinsertion. The ΔT varies between 3.7 - 5.3 % and 4.6 - 8.1 % at 550 and 663 nm, respectively. In the devices with PB (CHLnTrifxGly0.70, for LnTrifx = DyTrif0.15, SmTrif0.05, ErTrif0.05, and TmTrif0.05), during negative potential application, a reduction of PB occurs leading to the bleaching of the device, while the inverse process, coloration and/or oxidation, changes the ECD from transparent to blue. In these cases, the ΔT varies between 4.1 - 5.6 % and 4.1 - 9.2 % at 550 and 663 nm, respectively. Although in both cases, the transmittance change values are not very high, the color change differences are clearly visible in almost whole visible spectral range. Then, the obtained results showed that these electrolytes are promising materials to be applied in this kind of applications. In plasticized chitosan-PEO electrolytes doped with europium triflate, the sample with composition 50:50 presented the highest conductivity value of 1.92x10-8 S cm-1 at 30ºC and lowest activation energy of 85.26 kJ mol-1.Eletrólitos poliméricos (PEs) são materiais ionicamente condutores que apareceram como uma boa alternativa para substituir os tradicionais líquidos. Para preparar um PE é necessário um polímero hospedeiro, para atuar como uma matriz de base e, ao longo dos anos, muitos polímeros têm sido utilizados. Os polímeros naturais apareceram como alternativa aos sintéticos, e o quitosano tem sido amplamente investigado devido à sua elevada disponibilidade e às suas propriedades interessantes. Os polímeros condutores de iões são materiais-chave para o desenvolvimento de dispositivos comerciais e, portanto, a condutividade iónica é um parâmetro muito importante de um eletrólito. Assim, várias abordagens foram feitas para melhorar a condutividade iónica incluindo a plastificação, adição de sais, mistura de sais e mistura de polímeros. A influência dos diferentes sais de lantanídeos na matriz de quitosano foi avaliada. A concentração de sal influencia a condutividade iónica e a quantidade ideal de sal varia de acordo com o lantanídeo utilizado. Para as amostras com 0,05 g de sal, o eletrólito com triflato de cério apresentou valores de condutividade mais altos de 9,25×10-7 S cm-1 a 30ºC. No caso das amostras com 0,15 e 0,25 g de sais de lantanídeos, a condutividade iónica aumentou e atingiu valores máximos de 9,18×10-7 S cm-1 e 1,52×10-6 S cm-1, respetivamente, para as amostras com triflato de európio a 30ºC. As propriedades fotoluminescentes dos eletrólitos sólidos poliméricos à base de quitosano e triflato de európio foram avaliadas, e esses estudos indicaram as transições características de emissão e excitação do Eu3+. A presença de um único pico para a transição 5D0 → 7F0 é uma indicação de que os iões de európio ocuparam um único local de baixa simetria no hospedeiro polimérico, o que também foi corroborado pela emissão intensa a 615 nm (transição 5D0 → 7F2). No eletrólito bio-híbrido dopado com LiCF3SO3 e Eu(CF3SO3)3, obtiveram-se os valores de condutividade iónica na faixa de 5,38×10-6 (30ºC) a 8,77×10-5 (80ºC) S cm-1, que são superiores aos análogos eletrólitos poliméricos individualmente dopados com sais de EuIII e muito similares aos dopados com sais de lítio. Em um sistema binário de dois sais: triflatos de cério e lítio obteve-se a melhor condutividade iónica, 10-6 S cm-1 (a 30ºC), para as amostras com 0,15 g de quantidade total de sal. No caso dos materiais de quitosano com diferentes quantidades de glicerol, um aumento na quantidade de glicerol promoveu um aumento da condutividade iónica em 1 ou 2 ordens de grandeza e, portanto, essas amostras foram escolhidas para montar pequenos dispositivos electrocrómicos. Os ECDs com camada electrocrómica de WO3 (CHLnTrifxGly0,70, para LnTrifx = CeTrif0,10, DyTrif0,15 e SmTrif0,05) são quase transparentes logo após a montagem e, após a aplicação de potencial negativo, os dispositivos mudaram de quase transparente para cor azul. Essa mudança de cor está associada à redução do WO3 e à inserção simultânea de iões positivos, enquanto a aplicação do potencial inverso promove o retorno do dispositivo ao seu estado inicial, como resultado da oxidação do WO3 e desinserção de catiões. O ΔT varia entre 3,7 - 5,3% e 4,6 - 8,1% a 550 e 663 nm, respetivamente. Nos dispositivos com PB (CHLnTrifxGly0,70, para LnTrifx = DyTrif0,15, SmTrif0,05, ErTrif0,05 e TmTrif0,05)), durante a aplicação do potencial negativo, uma redução de PB ocorre levando ao branqueamento do dispositivo, enquanto o processo inverso, coloração e/ou oxidação, altera o ECD de transparente para azul. Nestes casos, o ΔT varia entre 4,1 - 5,6% e 4,1 - 9,2% a 550 e 663 nm, respetivamente. Embora em ambos os casos, os valores de mudança de transmitância não sejam muito altos, as diferenças de mudança de cor são claramente visíveis em quase todo o alcance espectral visível. Os resultados obtidos mostram que esses eletrólitos são materiais promissores a serem aplicados neste tipo de aplicações. Nos eletrólitos de quitosano-PEO plastificados e dopados com triflato de európio, a amostra com composição 50:50 apresentou o maior valor de condutividade de 1,92x10-8 S cm-1 a 30ºC e a menor energia de ativação de 85,26 kJ mol-1

Preparação e caracterização de electrólitos poliméricos para aplicação em dispositivos

Dissertação de mestrado em Técnicas de Caracterização e Análise QuímicaNos últimos anos as preocupações de arquitectos e industriais têm-se voltado para a produção de dispositivos com a capacidade de alterar a coloração de janelas ou superfícies. Tais dispositivos, designados de dispositivos electrocrómicos (ECD), permitem não só o controlo da transmissão ou reflexão da luz visível e energia solar como também um melhoramento a nível de conforto e eficiência energética. Os ECD até então produzidos são de vidro e recorrem a electrólitos líquidos, o que apresenta algumas desvantagens. Um dos problemas está relacionado com o facto de se utilizarem substratos grandes e unidades de produção dispendiosas. Por outro lado, o facto de o electrólito ser líquido complica a deposição de forma uniforme, levanta problemas de segurança para a saúde (devido às soluções utilizadas) e ainda, provoca problemas no controlo da transmitância (devido ao elevado tempo de comutação, o que limita a utilização em grandes áreas). É neste sentido que surge a intensa procura de novos materiais, mais baratos e com capacidade de suportar tais inconvenientes. O âmbito desta tese consiste em sintetizar novos materiais que possam ser utilizados como electrólitos sólidos poliméricos e que tenham a capacidade de substituir os mais tradicionais. Será também estudada a influência de alguns componentes constituintes dos electrólitos e, posteriormente, estes serão analisados segundo diversas técnicas. A Calorimetria Diferencial de Varrimento (DSC), Análise Termogravimétrica (TGA), Condutividade Iónica, Voltametria Cíclica, Microscopia Electrónica de Varrimento (SEM) e Raio X serão os métodos de análise utilizados. Foram ainda testados alguns dos electrólitos em dispositivos electrocrómicos.In recent years the concerns of architects and manufacturers have turned to the production of devices with the ability to change the colour of windows or surfaces. Such devices, known as electrochromic devices (ECD) allow not only the control of transmission or reflection of visible light and solar energy as well as an improved level of comfort and energy efficiency. The ECD ever produced are glass and turn to liquid electrolytes, which have some disadvantages. One of the problems is related to the fact of using large substrates, and manufacturing costly. On the other hand, the fact that the electrolyte to be liquid complicating the deposition of a uniform, poses security problems for the health (due to the solutions used) and also causes problems in controlling the transmittance (due to the high commuting time, which limited use in large areas). In this sense, there is the intense search for new materials, cheaper and able to endure such inconveniences. The scope of this thesis is to synthesize new materials that can be used as solid polymer electrolytes and have the ability to replace the more traditional. It will also study the influence of some constituent components of the electrolyte and then it will be analyzed by various techniques. The Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Ionic Conductivity, Cyclic Voltammetry, Scanning Electron Microscopy (SEM) and X-ray analysis methods are used. Some electrolytes were also being tested in electrochromic devices prototypes.Fundação para a Ciência e a Tecnologia (FCT) - Transístores de filme fino de electrocrómicos para aplicação em janelas inteligentes - ELECTRA - PTDC/CTM/099124/200

Advances of electrochromic and electro-rheological materials

This chapter discusses the main advances in electrochromic and electro-rheological materials. First are presented the different types of chromogenic materials, of which the electrochromic (EC) materials are an example, and the main factors that influence the performance of these materials. Electrochromic devices (ECDs) are a potential application of EC materials and the components of these devices are also discussed. Finally, different types of EC materials are presented and their main features are discussed. In electro-rheological (ER) materials, their definition and main components are presented. The different types of ER materials and some examples are shown here. Also the critical parameters that influence the ER effect are discussed. Finally, some applications of these materials are presented.- (undefined

A study on properties of chitosan-PEO electrolyte containing europium salt

Chitosan and poly(ethylene oxide) (PEO) powders were mixed in different ratios, and a fixed amount of europium triflate and glycerol were added to each mixture. The properties of these samples were studied by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and complex impedance spectroscopy. TGA revealed that the electrolytes are stable up to 145ºC. The samples’ morphology and structure are homogeneous, and a presence of small crystalline peaks in some XRD may be related to the salt that probably is not totally accommodate in the blended matrix. The best ionic conductivity values of 1.92x10-8 S cm-1 at 30ºC was registered for the sample with 50:50 composition.We are grateful to the Fundação para a Ciência e Tecnologia (FCT) through the Chemistry Research Centre of the University of Minho (Ref. UID/QUI/00686/2013 and UID/QUI/0686/2016) and for financial support of this work. M. M. Silva, R. Sabadini, and A. Pawlicka acknowledges Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for grants PVE 406617/2013-9, PDJ 152252/2016-9, and PP 305029/2013-4 provided by this institution.info:eu-repo/semantics/publishedVersio

Green polymer electrolytes of chitosan doped with erbium triflate

Green Solid Polymer Electrolytes (SPEs) containing Er3+ ions have been prepared by solvent casting process. Chitosan was used as host polymer and the trivalent cations, as erbium triflate (Er(CF3SO3)3), have been incorporated into the matrix. The thermogravimetric analysis were used to evaluate the thermal stability of the electrolytes and the minimum onset decomposition temperature was 139ºC. Morphology analysis have revealed the predominant amorphous character of the analysed samples. Complex Impedance Spectroscopy was used to evaluate the conductivity of the samples as a function of temperature. The most conducting electrolyte had higher amount of glycerol (CS(ErTrif)0.05Gly0.70) and displayed 2.06x10-5 and 5.91x10-4 S cm-1 at 30ºC and 90ºC, respectively. This SPE was chosen to assemble a small electrochromic device with glass/ITO/PB/CS(ErTrif)0.05Gly0.70/CeO2-TiO2/ITO/glass configuration, which behaviour was studied by cyclic voltammetry and transmittance.This work was supported by Fundação para a Ciência e a Tecnologia (FCT), program POCH/FSE (grant SFRH/BD/97232/2013 for R. Alves) and Chemistry Research Centre of the University of Minho UID/QUI/00686/2013 and UID/QUI/0686/2016. M.M. Silva and A. Pawlicka acknowledges National Council for Scientific and Technological Development (CNPq) for PVE 406617/2013-9 and PQ 305029/2013-4 grants.info:eu-repo/semantics/publishedVersio

Influence of cerium triflate and glycerol on electrochemical performance of chitosan electrolytes for electrochromic devices

Polymer electrolytes based on chitosan, glycerol, and cerium triflate are prepared by solution casting technique, and their properties are studied by complex impedance spectroscopy, thermal analysis (DSC and TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). The concentration of cerium triflate ranges between 0.00 and 55.72 wt%. The DSC results reveal a thermal event between 128 and 145ºC indicating a semi-crystalline nature of the samples. The best ionic conducting values of 1.46×10-6 and 8.74×10-5 S cm-1 at 30 and 90ºC, respectively are registered for the sample containing 33.32 wt% of salt. Moreover, it is stated that an increase of glycerol amount promotes an increase of the ionic conductivity up to maximum values of 1.67x10-5 and 4.93x10-4 S cm-1 at 30 and 90 ºC, respectively. SEM images show clusters formation for samples with high salt concentration, and X-Ray studies point a disappearance of large peak at 2θ ≈ 20º and appearance of narrow one at 2θ ≈ 10º, confirming crystalline domains formation. AFM results display the morphological characteristics of samples and 3.72 nm was the value obtained for the sample with less roughness.FAPESPCNPq - (PVE grant 406617/2013-9)CAPE

Luminescent polymer electrolytes based on chitosan and containing europium triflate

Solid polymer electrolytes based on chitosan and europium triflate were prepared by solvent casting and they were characterized by X-Ray diffraction, scanning electron microscopy (SEM), atomic force microscopy (AFM) and photoluminescence spectroscopy. The X-Ray diffraction exhibit that the samples were essentially amorphous with organized regions over the whole range of the salt content studied. The AFM analysis demonstrates that the smoother sample has roughness of 4.39 nm. Surface visualization through SEM revealed good homogeneity without any phase separation for more conductive samples and the less conductive showed some imperfections on the surface. The emission and excitation spectra display the characteristic bands of Eu(CF3SO3)3 in addition to broadbands corresponding to the polymer host. The excited state 5D0 lifetime values range from 0.29 – 0.37 ms for the studied samples.FAPESPCNPq - (PVE grant 406617/2013-9)CAPE

Solid polymer electrolytes based on chitosan and dy(CF3SO3)3 for electrochromic devices

In the present work, one host natural matrix (chitosan) was doped with glycerol and different amounts of dysprosium triflate salt (Dy(CF3SO3)3). The behaviour of the electrolytes was evaluated by thermal analyses (thermogravimetric analysis – TGA and differential scanning calorimetry – DSC), impedance spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). Sample with 0.15 g of Dy(CF3SO3)3 showed the best ionic conductivity values of 1.85x10-7 and 9.55x10-6 S cm-1 at 30 and 90 ºC, respectively. The lower values obtained for the other samples may be due to the appearance of aggregates, which corroborates with the XRD and SEM results. The new sample prepared with higher glycerol amount showed the highest conductivity values, namely 1.31x10-5 and 5.05x10-4 Scm-1 at 30 and 90 ºC respectively, so it was used to produce small electrochromic devices, which behaviour was evaluated.Chemistry Research Centre of the University of Minho UID/QUI/00686/2013 and UID/QUI/0686/2016. M.M. Silva and A. Pawlicka acknowledges CNPq for PVE 406617/2013-9, PQ 305029/2013-4, and 152252/2016-9 grants. F. Sentanin acknowledges CAPES for grant 1573926. Finally, the authors, acknowledges FAPESP (grant 2014/17174-4 spectrophotometer Jasco V670).info:eu-repo/semantics/publishedVersio