Temperature is one of the most important parameters for the performance, safety, and aging of lithium-ion batteries and has been linked to all main barriers for widespread commercial success of electric vehicles. The aim of this thesis is to highlight the importance of temperature effects, as well as to provide engineering tools to study these. The mass transport phenomena of the electrolyte with LiPF6  in EC:DEC was fully characterized in between 10 and 40 °C and 0.5 and 1.5 M, and all mass transport properties were found to vary strongly with temperature. A superconcentrated electrolyte with LiTFSI in ACN was also fully characterized at 25 °C, and was found to have very different properties and interactions compared to LiPF6  in EC:DEC. The benefit of using the benchmarking method termed electrolyte masstransport resistivity (EMTR) compared to using only ionic conductivity was illustrated for several systems, including organic liquids, ionic liquids, solid polymers, gelled polymers, and electrolytes containing flame-retardant additives. TPP, a flame-retardant electrolyte additive, was evaluated using a HEV load cycle and was found to be unsuitable for high-power applications such as HEVs. A large-format commercial battery cell with a thermal management system was characterized using both experiments and a coupled electrochemical and thermal model during a PHEV load cycle. Different thermal management strategies were evaluated using the model, but were found to have only minor effects since the limitations lie in the heat transfer of the jellyroll. / Temperatur är en av de viktigaste parametrarna gällande ett litiumjonbatteris prestanda, säkerhet och åldring och har länkats till de främsta barriärerna för en storskalig kommersiell framgång för elbilar. Syftet med den här avhandlingen är att belysa vikten av temperatureffekter, samt att bidra med ingenjörsverktyg att studera dessa. Masstransporten för elektrolyten LiPF6  i EC:DEC karakteriserades fullständigt i temperaturintervallet 10 till 40 °C för LiPF6-koncentrationer på 0.5 till 1.5 M. Alla masstransport-egenskaper fanns variera kraftigt med temperaturen. Den superkoncentrerade elektrolyten med LiTFSI i ACN karakteriserades även den fullständigt vid 25 °C. Dess egenskaper och interaktioner fanns vara väldigt annorlunda jämfört med LiPF6  i EC:DEC. Fördelen med att använda utvärderingsmetoden elektrolytmasstransportresistivitet (EMTR) jämfört med att endast mäta konduktivitet illustrerades för flertalet system, däribland organiska vätskor, jonvätskor, fasta polymerer, gellade polymerer, och elektrolyter med flamskyddsadditiv. Flamskyddsadditivet TPP utvärderades med en hybridbils-lastcykel och fanns vara olämplig för högeffektsapplikationer, som hybridbilar. Ett kommersiellt storformatsbatteri med ett temperatur-kontrollsystem karakteriserades med b.de experiment och en kopplad termisk och elektrokemisk modell under en lastcykel utvecklad för plug-inhybridbilar. Olika strategier för kontroll av temperaturen utvärderades, men fanns bara ha liten inverkan på batteriets temperatur då begränsningarna för värmetransport ligger i elektrodrullen, och inte i batteriets metalliska ytterhölje. / <p>QC 20150522</p> / Swedish Hybrid Vehicle Center

The research presented in this thesis includes a detailed investigation into factors influencing ionic conductivity in the crystalline polymer electrolyte PEO₆:LiPF₆. It has previously been shown that preparing PEO₆:LiPF₆ with PEO modified with larger –OC₂H₅ end groups increases ionic conductivity by one order of magnitude [¹],primarily due to disruption of the crystal structure caused by the inclusion of the larger end groups. In this study it is shown that by reducing PEO molecular weight in crystalline PEO₆:LiPF₆ ionic conductivity is also increased. This was attributed to an increasing concentration of polymer chain end regions upon lowering molecular weight resulting in the creation of more defects, as well as possible increases in crystallite size resulting in longer continuous pathways for ion transport. Similar results were observed using both polydispersed and monodispersed PEO to prepare complexes. In addition, it is demonstrated here that ionic conductivity in crystalline polymerelectrolytes is not confined to PEO₆:LiXF₆ (X=P, As, Sb)[²][³] type materials. The structures and ionic conductivity data are reported for a series of new crystalline polymer complexes: the alkali metal electrolytes. They are composed of low molecular weight PEO and different alkali metal hexafluoro salts (Na⁺, K⁺ and Rb⁺), and include the best conductor poly(ethylene oxide)₈:NaAsF₆ discovered to date [⁴], with a conductivity 1.5 orders of magnitude higher than poly(ethylene oxide)₆:LiAsF₆. A new class of solid ion conductor is reported: the crystalline small-molecule electrolytes. Such materials consist of lithium salts dissolved in low molecular weight glyme molecules [CH₃O(CH₂CH₂O)[subscript(n)]CH₃, n=1-12], forming crystalline complexes [⁵][⁶]. These materials are soft solids unlike ceramic electrolytes and unlike polymer electrolytes they are highly crystalline, are of low molecular weight and have no polydispersity. By varying the number of repeat units in the glyme molecule, many complexes may be prepared with a wide variety of structures. Here, ionic conductivity and cation transference number (t₊) data for several such complexes is presented [⁷][⁸][⁹].These complexes have appreciable ionic conductivities for crystalline complexes and their t₊ values vary markedly depending on the glyme molecule utilized. The differences in t₊ values can be directly attributed to differences in their crystal structures. [¹] Staunton, E., Andreev, Y.G. & Bruce, P.G. Factors influencing the conductivity of crystalline polymer electrolytes. Faraday Discussions 134, 143-156 (2007). [²] Gadjourova, Z., Andreev, Y.G., Tunstall, D.P. & Bruce, P.G. Ionic conductivity in crystalline polymer electrolytes. Nature 412, 6846 (2001). [³] Stoeva, Z., Martin-Litas, I., Staunton, I., Andreev, Y.G. & Bruce, B.G. Ionic Conductivity in the Crystalline Polymer Electrolytes PEO₆:LiXF₆, X = P, As, Sb. J. Am. Chem. Soc. 125, 4619-4626(2003). [⁴] Zhang, C., Gamble, S., Ainsworth, D., Slawin, A.M.Z., Andreev, Y.G. & Bruce, P.G. Alkali metal crystalline polymer electrolytes. Nature Materials 8, 580-584 (2009). [⁵] Henderson, W.A., Brooks, N.R., Brennessel, W.W. & Young Jr, V.G. Triglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (I). Chem. Mater. 15, 4679-4684 (2003). [⁶] Henderson, W.A., Brooks, N.R. & Young Jr, V.G. Tetraglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (II). Chem. Mater. 15, 4685-4690 (2003). [⁷] Zhang, C., Andreev, Y.G. & Bruce, P.G. Crystalline small-molecule electrolytes. Angewandte Chemie, International Edition 46, 2848-2850 (2007). [⁸] Zhang, C., Ainsworth, D., Andreev, Y.G. & Bruce, P.G. Ionic Conductivity in the Solid Glyme Complexes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 3,4). J. Am. Chem. Soc. 129, 8700- 8701 (2007). [⁹] Zhang, C., Lilley, S.J., Ainsworth, D., Staunton, E., Andreev, Y.G., Slawin, A.M.Z. & Bruce, P.G. Structure and Conductivity of Small-Molecule Electrolytes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 8-12). Chem. Mater. 20, 4039-4044 (2008).

Crohn's disease is a chronic inflammatory bowel disease which may affect any part of the gastrointestinal tract with a preference for the terminal ileum and ileocaecal region. The disease was first described in 1932 and has increased during the last decades. The clinical manifestations could be referred to as inflammation, malabsorption and obstruction. The annual incidence of Crohn's disease in the county of Västerbotten, North Sweden, was found to be 4.9/105 inhabitants. In a study of 87 patients in a medical gastrointestinal unit, 23% of non-operated patients and 66% of resected patients had increased fecal fat excretion. D-xylose test and lactose tolerance test were abnormal 1n 19% and 24% respectively of the non-operated patients. No clear relation could be found between the outcome of these malabsorption tests and localization, extension or activity of the disease. This suggests the cause of malabsorption 1n Crohn's disease to be complex and multi- factorial . The morphology of jejunal biopsies from 18 patients with Crohn's disease elsewhere 1n the gastrointestinal tract demonstrated an abnormal picture 1n 13 patients when assessed by light microscopy and scanning electron microscopy. A high proportion of these patients had abnormal Intestinal absorptive tests. Skeletal muscle biopsies were performed 1n 13 patients showing a depletion of muscle potassium content and more Infrequently low skeletal muscle magnesium content. This depletion 1s not reflected by subnormal plasma concentration. In the Initial clinical assessment of a new gamma labelled synthetic bile ac1d-SeHCAT, 45 patients, 19 of whom had Crohn's disease, were studied. The outcome of the test correlated well with the excretion of fecal bile acids. It was possible to discriminate patients with terminal Ileal disease from other patient groups. In a follow-up study, the SeHCAT test was modified as to make it simpler and to shorten the test period. Nine patients with Crohn's disease were tested, showing a suffi cent accuracy of the outcome of the test within 48 hours, using simple equipment available in many hospitals. The elimination of radioactivity was calculated as WBR50*» the time for 50% of the administered dose to be excreted. This gives information as to the rate of excretion, reflecting the degree of terminal ileal malfunction. / <p>S. 1-41: sammanfattning, s. 43-115: 5 uppsatser</p> / digitalisering@umu

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / Electrochemical behaviour of Ce, Fe, Cr,V and Mn in the presence of DTPA, EDTA, EDDS, NTA ligands were investigated by using cyclic voltammetry, a rotating disc electrode and electrochemical impedance spectroscopy for use in redox flow battery (RFB) systems. RFB is currently used for energy storage, the vanadium, which is used in most of the RFB’s, however suffers from species crossover and sluggish reactions, which limit the lifetime of the battery. These various ligands and metal complexes mentioned above where all examined to identify the suitable and favoured electrolyte that can be used for a RFB system. Kinetic parameters such as potential, limiting current, transfer coefficient, diffusion coefficients, and rate constants were studied. RDE experiments confirmed that the parameters measured by CV are similar under hydrodynamic conditions and can be used to determine the kinetic parameters of the redox couples. The use of DTPA as a ligand for complexation of Ce(IV) gave more favourable results compared to other ligand with various metal complexes used in this study [1-3]. The results of kinetic studies of Ce(IV)–DTPA complex shows promise as an electrolyte for a redox flow battery. The separation of V(IV)/(V), Fe (III)/(IV),Cr(III)/(IV),Mn (III)/(IV) and Ce(III)/(IV) with various ligands (EDTA, EDDS, NTA and DTPA) were also investigated using capillary electrophoresis. To understand the speciation of these metal complexes as used in this study and particularly the vanadium, for the reason that it has a complicated (V) oxidation state. The charge/discharge performance of all electrolytes used in this work was determined and a high voltage achieved when Ce-DTPA was used, and it is compared to that of the vanadium electrolyte currently in use. This was evaluated with systems studied previously. Therefore, Ce-DTPA will be a suitable electrolyte for redox flow battery systems.

Thesis (PhD)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Several experiments [1, 2, 3, 4] have shown that e ective attractive interactions exist between con ned like-charged macromolecules. Theoretical approaches have not reached consensus as to precisely what the mechanism for the attraction is, but it is agreed that comprehending the role of the counterion arrangement around macromolecules is crucial for understanding the e ective macromolecule interactions. It is generally assumed that attraction only occurs in the limit of strong electrostatic coupling and is driven by correlation e ects that are neglible in a mean- eld approach, which is valid in the weak-coupling limit. However, in some experimental situations attraction occurs even in the limit of weak-coupling. We consider a eld-theoretic approach that includes uctuations to study the Coulomb interactions of con ned counterions with a single exible charged spherical macromolecule that can expand or collapse uniformly by changing its radius. We show how the linearised eld-theory (valid in the weak-coupling limit) is mapped onto the square-well potential of Quantum Mechanics. The con nement leads to bound states being present in the spectrum at all times. Bound states are non-perturbative and we investigate the role they play in the physics of the system. Some of the e ects are rather counter-intuitive. Firstly, upon expanding the macromolecule in a xed con nement volume, the uctuation part of the free energy favours a decrease in the free energy. Secondly, upon increasing the temperature to high but nite values, the uctuation contribution does not dominate the free energy as would be expected. The mathematical origins of these e ects are dicussed in detail and as part of the analysis we introduce a novel regularisation scheme for computing the functional determinant arising in the model considered where the cut-o is speci ed unambiguously in terms of physical parameters. / AFRIKAANSE OPSOMMING: Verskeie eksperimente [1, 2, 3, 4] toon dat makro-ione met gelyksoortige ladings, in `n eindige volume, `n e ektiewe aantrekkende krag ondervind. Alhoewel daar nog geen konsensus oor die presiese meganisme vir die aantrekking bereik is nie, is dit duidelik dat die rol van \counter-ion" rangskikking rondom die makro-ione belangrik is om die e ektiewe wisselwerkings te verstaan. Dit word algemeen aanvaar dat die aantrekkende krag slegs in die limiet van sterk elektrostatiese koppeling plaasvind en dat dit `n gevolg van \counter-ion" korrelasies is wat weglaatbaar is in `n gemiddelde veld benadering, wat geldig is in die limiet van swak elektrostatiese koppeling. Daar bestaan egter eksperimentele situasies waar die aantrekking in die limiet van swak elektrostatiese koppeling waargeneem word. Ons bestudeer die Coulomb wisselwerking tussen \counter-ions" en `n enkele rekbare sferiese makro-ioon vanuit `n veld-teoretiese beskouing wat uktuasies in ag neem. Die sferiese makro-ioon kan vergroot of verklein deur sy radius uniform te verander. Ons toon aan dat die gelineariseerde veldeteorie (geldig in die limiet van swak elektrostatiese koppeling) op die eindige-diepte put Kwantummeganiese model afgebeeld kan word. Die eindige volume van die sisteem het tot gevolg dat daar altyd gebonde toestande in die spektrum voorkom. Gebonde toestande is `n suiwer nie-steuringsteoretiese e ek en ons ondersoek die rol wat dit speel in die sika van die sisteem. Die teenwoordigheid van die gebonde toestande in die spektrum het `n paar teen-intuitiewe e ekte tot gevolg. Eerstens word die vrye energie verlaag soos die makro-ioon in `n eindige volume vergroot. Tweedens oorheers die uktuasie bydrae nie die vrye energie met toenemende temperatuur soos verwag sou word nie. Ons bespreek die wiskundige oorsprong van hierdie e ekte. As deel van die analise ontwikkel ons `n nuwe regulariseringstegniek vir die berekening van funksionaalintegrale waar die regulariseringsparameter ondubbelsinnig in terme van siese hoeveelhede uitgedruk kan word.

Des travaux récents ont montré que le transfert d'espèces neutres à travers différents types de membranes est modifié selon la composition ionique. En présence de sels, le flux de soluté est augmenté, ce qui peut conduire à une dégradation des performances des procédés. Ce travail présente les résultats d'une étude expérimentale dans laquelle les flux de diffusion de sucre dans différentes matrices ioniques, eau et électrolytes, ont été déterminés à travers des membranes échangeuses d'ions. Une procédure spécifique a été mise au point pour déterminer l'impact des différentes interactions sur les flux de solutés. Les résultats montrent que, dans les conditions étudiées, la modification du transfert de matière est due principalement aux interactions entre le matériau membranaire et la solution. Une corrélation a été établie entre l'échelle d'hydratation des contre-ions de la membrane et le flux de soluté.

Neste trabalho apresenta-se um estudo por Ressonância Magnética Nuclear (RMN) dos condutores iônicos vítreos (fluoroindatos) e poliméricos, com base nos Poli-Óxidos de Propileno (PPO). Nosso principal objetivo é investigar as propriedades de RMN dos íons responsáveis pela condução iônica nestes condutores amorfos. Entre as propriedades estudadas estão os mecanismos de relaxação nuclear em função da temperatura e freqüência, a forma de linha e o segundo momento associado as linhas de ressonância. No caso dos complexos poliméricos, nossos resultados indicam que a condutividade é governada pelos movimentos segmentários de cadeia polimérica. A análise do segundo momento das linhas, permitiu determinar a intensidade das interações dominantes que estão envolvidas nestes complexos. Dos resultados de relaxação em polímeros, obtivemos os parâmetros importantes do movimento iônico, tais como: a energia de ativação (Ea), a freqüência de saltos (&#9640 e a dependência em freqüência da taxa de relaxação. Nossos resultados refletem a natureza desordenada destes materiais e a complexidade do processo de condução iônica nestes sistemas. Nos estudos realizados em vidros fluorados, pudemos discriminar os mecanismos re relaxação spin-rede presentes. Estes resultados mostram que, abaixo da temperatura de transição vítrea (Tg), T1-1 é fracamente dependente da freqüência e da temperatura. Enquanto que acima de Tg, T1-1 passa a ter um comportamento típico de sistemas termicamente ativados. Um terceiro mecanismo (contribuição paramagnética) foi estudado nas amostras de vidros fluoroindatos dopados com um íon paramagnético (Gd3+), onde pôde se observar das medidas da taxa de relaxação spin-spin (T2-1), o comportamento descrito pela interação hiperfina de contato, entre o núcleo de 19F em difusão com o spin eletrônico do íon paramagnético. Aborda-se ainda, aspectos técnicos necessários a utilização e desenvolvimento do espectrômetro, tais como: sondas de alta e baixa temperaturas, circuitos de recepção e softwares de controle / In this work we report a Nuclear Magnetic Resonance (NMR) study of two types of ionic conductors: fluoroindates glasses and polymers based on polypropylene oxide (PPO). We have investigated the nuclear spin relaxation process of the diffusing ions by measuring relaxation times and the second moment of the resonance line as a function of temperature and frequency. In the case of the polymeric systems our results indicates that the conduction mechanism is d e d by segmental motions of the polymer chain. Analysis of the second moment allow us to determine the intensity of the main interactions involved and, from relaxation measurements, important parameters of the ionic motion can be extracted. Our results are compatible with the complexity of the ionic conduction process characteristic of these disordered systems. Studies realized with the fluoride glass systems allow us to distinguish between the different spin-lattice relaxation mechanisms. Results show that bellow the vitreous transition temperature (Tg), T1-1 has a weak dependence with temperature and frequency. The behavior of T1-1 above Tg is typical of thermally activated systems, from which we could calculate the activation energy. A third mechanism (paramagnetic contribution) was studied in the fluoride glasses doped with (Gd3+). In this case, the spin-spin relaxation process is dominated by the contact hyperfine interaction between diffusing 19F nuclei and the electronic spin of the paramagnetic ion. We still discuss in this work different technical aspects of the NMR spectrometer, such as the low and high temperature probes and software for control and data analysis

Neste trabalho foi estudado o eletrólito sólido polimérico obtido através da plastificação do amido rico em amilopectina com glicerol em porcentagem de 30% em ralação a massa do amido utilizado, e contendo perclorato de litio (LiClO4), com uma razão [0]/[Li] = 10 (AGL). Com o objetivo de estudar a influência da umidade relativa nas propriedades de transporte iônico do eletrólito, foi utilizada a técnica de Ressonância Magnética Nuclear RMN. Neste trabalho, também, foram utilizadas outras técnicas de caracterização como: DSC, TGA e condutividade A.C. No estudo de RMN, foram realizadas medidas da forma de linha e da taxa de relaxação spin-rede do 1H e do 7Li em função da temperatura, a fim, de estudar a mobilidade do próton e do íon lítio no complexo polimérico. Os resultados desacoplamento do 7Li {1H} medidos na temperatura de 183K mostraram que 80% da largura de linha foi atribuída a interação heteronuclear Li-H. Os resultados da relaxação mostraram um aumento na mobilidade do complexo polimérico e do íon lítio com o aumento da hidratação do eletrólito. Os valores para a energia de ativação são da ordem de 0.20eV para o próton e 0.23eV para o lítio, consistente com os valores encontrados em outros eletrólitos sólidos poliméricos (0.2 - 0.3eV) / In this work we report the study of solid polymer electrolyte obtained from amylopectin rich starch plasticized with 30% in mass of glycerol and lithium perchlorate (LiClO4) with a reason [0]/[Li] = 10. With the objective to study the influence of the relative humidity in the properties of ionic transport of the electrolyte, the technique of Nuclear Magnetic Resonance - NMR was used. The samples were also characterized by DSC, TGA and A.C. conductivity. The mobility of protons and lithium ion were study through the temperature dependence of 1H and 7Li NMR lineshape and spin-lattice relaxation times. The 7Li {1H} decoupling results measured in the temperature of 183K, shows that 80% of the width of line was attributed to Li-H heteronuclear interaction. The relaxation results showed an increase of mobility of proton and lithium ion in the polymer complex with the increase of the relative humidity of the electrolyte. Activation energy of the arder of 0.20eV for the proton and 0.23eV for lithium were obtained from NMR measurements, consistent with the values found in other solid polymer electrolyte (0,2 - 0.3eV)

Simulações por Dinâmica Molecular (MD) de eletrólitos poliméricos baseados em poli (oxietileno), POE, e líquidos iônicos derivados do cátion 1-alquil-3-metilimidazólio e ânion hexafluorfosfato foram realizadas. Os parâmetros do potencial intermolecular e intramolecular foram obtidos de simulações MD prévias, a partir de um modelo de átomos unidos para POE e cátions imidazólio, ou seja, átomos de hidrogênio não são considerados explicitamente. Investigação sistemática da concentração de líquido iônico (LI), temperatura, e comprimento da cadeia 1-alquil, [1,3-dimetilimidazólio]PF6 e [1-butil-3-metilimidazólio]PF6, bem como seus efeitos sobre a estrutura de equilíbrio foram realizadas, constatando completa dispersão dos líquidos iônicos na matriz polimérica. Foram observadas mudanças conformacionais na cadeia de POE, devido à interação POE-LI. Além disso, os sistemas apresentaram ordem em escala intermediária (IRO) similar aos eletrólitos poliméricos de sais inorgânicos simples. Estes resultados foram motivadores para realização de ensaios experimentais com de poli (etileno glicol) dimetil éter, PEGdME, e hexafluorfosfato de 1-butil-3-metilimidazólio, caracterizado por análises térmicas TG e DSC, difração de raio-X e espectroscopia por impedância eletroquímica. Correlações com a previsão teórica foram reveladas, em especial quanto à coordenação POE-LI, que ocorre principalmente na fase amorfa. Condutividades da ordem de 10-3 S.cm-1 a altas temperaturas foram observadas. O estudo computacional sobre a dinâmica dos sistemas revelou mobilidade iônica em POE/[bmim]PF6 maior que em POE/[dmim]PF6, além de mostrar que a adição de líquido iônico ao polímero causa diminuição na dinâmica das cadeias de POE. Condutividades calculadas para POE/[bmim]PF6 estão em concordância qualitativa com as obtidas para o sistema PEGdME-[bmim]PF6. A redução dos pares iônicos frente aos eletrólitos poliméricos de sais inorgânicos é a distinta evolução no tempo da função de van Hove para ânions e cátions, bem como a razão &#954;/&#954;NE maior, por exemplo, em comparação ao sistema POE- LiClO4. / Molecular dynamics simulations of polymer electrolytes based on poly (oxyethylene), POE, and ionic liquids derived from 1-alkyl-3-methylimidazolium hexafluorophosphate were performed. We used united atom models, i.e. hydrogen atoms of the PEO chain and 1,3-dialkylimidazolium cations are not explicitly considered. All of the potential parameters for intramolecular terms can be found in previous MD simulations of POE-LiCLO4 and ionic liquids systems. A systematic investigation of ionic liquid concentration, temperature, and the 1-alkyl-chain length, [1,3-dimethylimidazolium]PF6, and [1-butyl-3-methylimidazolium]PF6, effects on resulting equilibrium structure is provided. It is shown that the ionic liquid is dispersed in the polymeric matrix and conformational changes on PEO chains upon addition of the ionic liquid are identified. Long-range correlations are assigned to non-uniform distribution of ionic species within the simulation box. Experimental data were obtained from thermal analysis, x-ray diffraction and electrochemical impedance spectroscopy from poly (ethylene glycol) dimethyl ether, PEGdME, and 1-butyl-3-methylimidazolium hexafluorophosphate. Correlations with previous theoretical results were revealed and coordination of the IL by the polymer occurs mainly in the amorphous phase. It has been obtained ionic conductivity &#954; ~ 10-3 S.cm-1 for polymer electrolytes at high temperatures. Ionic mobility in PEO/[bmim]PF6 is higher than in PEO/[dmim]PF6 and the structural relaxation in PEO/[dmim]PF6 and PEO/[bmim]PF6 also indicated that the material containing the smaller cation [dmim]+ exhibits more significant slowing down on the dynamics of PEO chains. Clear indications of reduced strength in ion correlations are the distinct time evolution of van Hove correlation functions for anions and cations, and the higher &#954;/&#954;NE ratio in comparison with, for instance, the PEO/LiClO4.

A busca por fontes de energia é algo inerente à história da sociedade. O impacto da revolução industrial e a evolução da produção manufaturada, forçaram a um crescimento do uso dos combustíveis fósseis. Crises do petróleo, crescimento populacional, tratados ambientais e o reconhecimento da influência das atividades humanas nos fenômenos de mudanças climáticas levaram ao aprofundamento das pesquisas e aplicações em Energias Renováveis e fontes menos poluentes. Dentre essas diversas pesquisas destaca-se o desenvolvimento de células eletroquímicas, que em muitas vezes, estão relacionadas à problemas de poluição ambiental. Células eletroquímicas são dispositivos capazes de gerar e acumular energia através de reações químicas e bioquímicas. Estudos nessa área são importantes, visto que muitas vezes existem dúvidas de ordem técnica para suas aplicações no design de produtos eletroeletrônicos, que buscam reduzir seu impacto, principalmente, no descarte final. Neste sentido, a presente pesquisa buscou contribuir com dados técnico-científicos orientadores para a geração da microenergia, a partir da utilização de materiais naturais para fabricação da célula bioquímica. Diante desse objetivo, foram selecionados materiais naturais dentre um conjunto de folhas de espécies comuns no estado do Rio Grande do Sul, Brasil, com possível potencial para atuarem como eletrólito na microgeração de energia de corrente contínua. Após os ensaios de caracterização, foram montados sistemas de células eletroquímicas composta por eletrodos de Cobre e Zinco e os materiais selecionados como eletrólito. Os resultados apontaram que as folhas de limão, de bergamota, e de laranja apresentam um potencial para geração de energia. Com base na pesquisa, verificou-se que existem boas possibilidades para microgeração de energia utilizando eletrólitos com matérias naturais. / The search for energy sources is something inherent in the history of society. The impact of the industrial revolution and the evolution of manufactured production forced the use of fossil fuels to grow. Oil crises, population growth, environmental treaties and the recognition of the influence of human activities on the phenomena of climate change have led to the deepening of research and applications in Renewable Energies and less polluting sources. Among these several types of research the development of electrochemical cells, which in many cases, are related to the problems of environmental pollution, stands out. Electrochemical cells are devices capable of generating and accumulating energy through chemical and biochemical reactions. Studies in this area are important since there are often technical doubts for their applications in the design of electrical and electronic products, which seek to reduce their impact, mainly in the final disposal. In this sense, the present research sought to contribute to technical-scientific data guiding for the generation of micro-energy, from the use of natural materials to manufacture the biochemical cell. In view of this objective, natural materials were selected from a set of leaves of common species in the state of Rio Grande do Sul, Brazil, with a potential to act as an electrolyte in the micro energy generation of direct current. After the characterization tests, electrochemical cell systems composed of Copper and Zinc electrodes and the materials selected as electrolyte were assembled. The results indicated that lemon, bergamot, and orange leaves have a potential for energy generation. Based on the research, it was verified that there are good possibilities for microgeneration of energy using electrolytes with natural materials.