• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    Supramolecular fluid. The present invention relates to a supramolecular fluid for application in redox reactions. More specifically, the fluid of the invention comprises a quaternary ammonium salt. The invention also relates to compositions of the quaternary ammonium salt. And to the uses of them. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2797556A1
    申请号:ES202030929
    申请日:2020-09-14
    公开日:2020-12-02
    发明作者:Lopez Maria Del Carmen Gimenez；Fernandez Jose Francisco Rivadulla；Lucas Carlos Herreros；Bueno Carlos Lopez
    申请人:Universidade de Santiago de Compostela；
    IPC主号:
    专利说明:

    [0001] Supramolecular fluid
    [0003] Technical sector
    [0005] The present invention relates to a supramolecular fluid. More specifically, the fluid of the invention comprises a quaternary ammonium salt or a quaternary phosphonium salt. The invention also relates to compositions of the quaternary ammonium salt or the quaternary phosphonium salt, and the uses thereof.
    [0007] Background of the invention
    [0009] Among the electrolytes commonly used, the bromide anion has many advantages: it is inexpensive, with high solubility in water and a high diffusion coefficient. However, it gives rise to unwanted side reactions because it reacts with the bromine that is formed in the oxidation process, giving rise to the tribromide ion (Br- 3 ) that precipitates as a yellow solid (Energy Environ. Sci, 2014, 7 , 1990; Nat. Commun. 6: 7818 ( 2015)).
    [0011] Thus, it is still necessary to find an electrolyte with all the advantages of bromide and that also avoid those side reactions in which the tribromide species is formed.
    [0013] Among the metallic electrodes used, those based on transition metals such as copper present important advantages in the implementation of electrochemical processes given their low cost and availability compared to noble metals. However, they suffer from limited stability in aqueous electrolytes and especially those with chloride ions, due to the unwanted formation of a solid film of copper chloride (CuCl) on the surface of the electrode that reacts with more chloride ions to give rise to species. anionic soluble (CuCk-) (Nature Communications 2018, 9, 1; Corrosion Science 2018, 140, 111).
    [0015] Therefore, it is still required to identify electrolytic media that inhibit copper corrosion in aqueous media with a high concentration of chloride ions (the case of sea water) where soluble charged species (CuCk-) are formed.
    [0016] The present invention provides a new fluid that is useful as an electrolyte in batteries. Furthermore, the authors have shown that this fluid inhibits or prevents the deterioration of the electrodes, for example the oxidation of the electrodes or the corrosion of the same.
    [0018] Thus, in a first aspect the invention is directed to a supramolecular fluid stable under atmospheric conditions characterized in that it comprises a quaternary ammonium halide or a quaternary phosphonium halide, with a concentration equal to or greater than 2 m (2 molal) in a solution watery.
    [0020] In addition, the authors of the invention found that, in addition to the fluid of the invention, a composition is capable of avoiding the formation of tribromide and making the electrochemical reaction using bromide as electrolyte reversible. Specifically, they found that a quaternary ammonium halide or a quaternary phosphonium halide in a certain concentration range completely prevents the formation of the tribromide ion.
    [0022] In a second aspect, the invention is directed to a composition comprising a quaternary ammonium halide or a quaternary phosphonium halide in a concentration equal to or greater than 0.6 m and equal to or less than 1.99 m in aqueous solution.
    [0023] In a third and fourth aspect, the invention is directed to an electrolyte and a cell comprising the fluid of the invention or the composition of the invention.
    [0025] A fifth aspect of the invention is directed to the use of the fluid or the composition.
    [0027] Description of the figures
    [0029] Figure 1 depicts the differential scanning calorimetry heating and cooling curves for various aqueous solutions of tetrabutylammonium bromide in water. It can be seen how the melting peak of the ice (at zero degrees Celsius) gradually disappears as the concentration of the ammonium salt increases, until it disappears completely within 2 m. At that concentration and at higher concentrations, only the characteristic double peak of clathrate fusion is visible, demonstrating the absence of free water in the system.
    [0031] Figure 2 represents the variation of the compressibility of tetrabutylammonium bromide in water at different concentrations against temperature (Figure 2a); heat capacity of tetrabutylammonium bromide in water at different concentrations versus temperature (Figure 2b); and the compressibility and thermal diffusivity versus the concentration of tetrabutylammonium bromide in water (molal) (Figure 2c) at room temperature. White squares refer to compressibility and black circles refer to thermal diffusivity. A minimum is observed in compressibility and thermal diffusivity at room temperature for the concentration range 2-4 m.
    [0033] Figure 3 represents the cyclic voltammogram that occurs when tetrabutylammonium bromide is used as electrolyte at a concentration of 2 m and shows the comparison with the same redox reaction when 2 m potassium bromide is used.
    [0035] Figure 4 represents the cyclic voltagram at different concentrations of tetrabutyl ammonium bromide in water. It can be seen that only at concentrations greater than 0.6 m the redox process of bromide is reversible based on the presence of a well-defined anodic (i a ) and cathodic (i c ) peak that have a relationship close to 1. The current increases with the concentration of Br " anions.
    [0037] Figure 5 represents the Raman spectrum of the electrodes after the redox reaction using different concentrations of tetrabutylammonium bromide as electrolyte. It is shown that the tribromide anion (band at 160 cm "1 ) is formed only in the electrodes that were exposed to concentrations lower than 0.6 m as a consequence of the low reversibility of the process.
    [0039] Figure 6 represents the cyclic voltagram of different quaternary ammonium bromides.
    [0040] Figure 7 represents the cyclic voltammograms of Pt / C in a saturated solution of hydrogen of 2 m KBr and 2 m TtBABr at 50 mV / s. The region between ~ -0.6 at 0 V corresponds to the adsorption / desorption of hydrogen on the surface of platinum nanoparticles, while the one between ~ 0.2 to 0.6 V is related to the surface oxidation / reduction of Pt. schematics (right panel) represent these processes; The surface oxidation / reduction of Pt in water is inhibited at 2 m TtBA due to the low reactivity of the water molecules in our supramolecular fluid. As shown in the figure the cathodic peak at 0.38 V corresponds to the reduction of the electrochemically oxidized Pt surface. Interestingly, the oxidation of Pt in H 2 O is completely inhibited in the aqueous solution of TtBABr (2 m), as reflected in the total absence of any measurable faradaic current at positive potentials. Mention that the TtBA salt is not blocking the electrode surface, as evidenced by the fact that the Pt is still electrochemically active at negative potentials where hydrogen adsorption / desorption takes place. Therefore, the reactivity of water molecules is limited by their strong interaction in the supramolecular fluid structure.
    [0042] Figure 8 represents the cyclic voltammograms for a copper electrode (wire) used as a working electrode where the corrosion inhibiting effect of the tetrabutylammonium chloride electrolyte (2 m) is compared with the corrosive effect of a potassium chloride solution. , both solutions with the same aqueous concentration of chloride ions (2 m) in a nitrogen atmosphere and at a speed of 50 mV / s.
    [0044] Figure 9 represents an image of the electrochemical cell after chronoamperometric experiments (0.3 V) using tetrabutylammonium chloride (2 m) as electrolyte (colorless solution). After the chronoamperometric experiment after applying 0.3V for 300 seconds, no change in the color of the electrolyte was observed. However, when potassium chloride (2 m) is used as electrolyte instead of tetrabutylammonium chloride, the initially colorless potassium solution turns brown due to copper corrosion, which is consistent with the presence of a band below 300 nm in its ultraviolet-visible spectrum.
    [0046] Figure 10 represents Raman spectra of the surface of a copper electrode (wire) used as a working electrode where the corrosion inhibiting effect of the tetrabutylammonium chloride electrolyte (2 m) is compared with the corrosive effect of a chloride solution. of potassium at the same concentration (2 m). The electrode surface remains completely intact after chronoamperometric experiments (0.3V) in the presence of TtBACl (only bands related to the presence of the TtBA + cation, * are observed), while in potassium chloride (2 m) the presence of of copper oxide and copper chloride as a consequence of corrosion. The images on the right show the areas analyzed (scale: 30 | im).
    [0048] Detailed description of the invention
    [0050] The present invention provides a new supramolecular fluid with the physicochemical characteristics that are detailed herein and that characterize said fluid.
    [0051] A first aspect of the invention is directed to a supramolecular fluid stable in atmospheric conditions characterized in that it comprises an ammonium halide quaternary or a quaternary phosphonium halide, with a concentration equal to or greater than 2 m in an aqueous solution. In a particular embodiment, the supramolecular fluid of the invention is stable under atmospheric conditions and is characterized in that it consists of a quaternary ammonium halide or a quaternary phosphonium halide, with a concentration equal to or greater than 2 m in an aqueous solution
    [0053] Thus, at a concentration of 2 m or higher, each macromolecule in this fluid is composed of a quaternary ammonium halide or a quaternary phosphonium halide and a number of water molecules between 30 and 38 so that all molecules of water are part of these structures, leaving no free water. So the fluid is supramolecular all of it.
    [0055] In the present invention, "supramolecular fluid" is understood as a fluid composed of the association of water molecules, with a stable structure, so that all the water molecules are part of its structure, and that they behave collectively as which refers to its physicochemical and transport properties.
    [0057] The fluid of the present invention is stable under atmospheric conditions. Atmospheric conditions are understood to be the standard working conditions in a laboratory in which neither the temperature nor the pressure of the environment are modified; in general the atmospheric conditions can be between 15 ° C and 30 ° C, at a pressure of approximately 1 atm. The fluid of the invention is stable under these conditions, and in fact it is possible to obtain it under atmospheric conditions, without the need for any variation in temperature or pressure to form it, unlike clathrates that need low temperatures and high pressures to form their crystalline structures. The fluid of the invention, once formed, is stable and for this reason its properties do not vary, nor does it decompose over time, and the studies carried out by the authors of the invention show that it is stable for more than 6 months.
    [0059] The formation of the fluid of the invention depends on the concentration of the ammonium or phosphonium halide in aqueous solution. In a particular embodiment, the aqueous solution is water. Thus, it can be observed that at concentrations below 2 m part of the water in the solution is free, and there is a greater amount of free water the lower the concentration of the ammonium salt. At a concentration equal to or greater than 2 m, there is no presence of free water and all the water molecules form a structural part of the fluid (figure 1, example 1).
    [0060] In a preferred embodiment, of the first aspect of the invention, the concentration of the quaternary ammonium salt or of the quaternary phosphonium salt is between 2 m and 30 m, preferably between 2 m and 10 m, more preferably between 2 m and 4 m , preferably between 2.3m and 10m, preferably between 2.3m and 3.6m, preferably between 2m and 3.6m.
    [0061] As can also be seen in Figure 1, the melting point temperature of the fluid of the invention (that is, with concentrations greater than 2 m) is 9-12 ° C, therefore higher than the melting point of ice. , indicating greater structural stability.
    [0063] The thermal conductivity of the fluid of the invention also shows that the concentration of the ammonium or phosphonium is fundamental and it can be observed that when the concentration increases, the thermal diffusivity decreases (Figure 2). Furthermore, other physicochemical properties of the fluid, such as its compressibility, speed of sound propagation, or heat capacity, show an anomaly at a concentration of 2 m or higher, which demonstrates the uniqueness of the liquid in these compositions.
    [0065] In examples 1 and 2 of the present specification, it is demonstrated that the fluid of the invention is a supramolecular fluid, with its characteristic properties, in which the water and the ammonium salt are found to form a single structure, which can be to resemble that of a crystalline clathrate in solid state; with the advantage that our fluid does not have that crystalline structure nor is it a solid and therefore it is possible to use it in applications that a clathrate would not reach, such as, for example, as an electrolyte in a redox process.
    [0067] In Example 3A, it is shown how the fluid of the invention is useful as an electrolyte in a Br 2 / Br redox process. "In this example, the efficiency of quaternary ammonium bromide at a concentration of 2 m is compared with potassium bromide, used as electrolytes, and it is shown that while when using potassium bromide the tribromide species (Br 3 -) is formed and the redox reaction is less efficient or ends, when quaternary ammonium bromide is used at a concentration of 2 m this by-product is not shape (see example 3C and figure 5). This is because the quaternary ammonium bromide fluid at a concentration of 2 m is capable of capturing Br 2 and thus avoid the formation of tribromide. An additional advantage of the fluid of the invention is that it allows the Br 2 confined within it to be reduced to bromide, favoring a reversible electrolytic process. Thus, when the quaternary ammonium bromide fluid is used at a concentration of 2 m, the redox process is reversible. you.
    [0068] As demonstrated in example 3B, at different concentrations of the fluid, for example at a concentration of 2 m and higher, the same results are obtained, making the redox process reversible and avoiding the formation of tribromide. But even at lower concentrations the process is also reversible. Thus, a mixture of tetrabutylammonium bromide in water at lower concentrations in which not all the water is forming a kind of clathrate as occurs in the fluid, but some percentage of free water is observed (see example 1 and figure 1), It is also useful to carry out a redox process, and even more so, so that this Br 2 / Br - redox process is reversible.
    [0070] When ammonium bromide is used at concentrations below 0.5 m, the redox process is not reversible, as can be seen in Figure 4 at a concentration of 0.2 m.
    [0072] Thus, in a second aspect, the invention is directed to a composition comprising a quaternary ammonium halide or a quaternary phosphonium halide in a concentration equal to or greater than 0.6 m and equal to or less than 1.99 m in aqueous solution.
    [0073] In a preferred embodiment, the formula of the quaternary ammonium halide of the fluid of the invention is X - (Alk 4 N) + , where X is selected from chlorine, bromine and iodine, and Alk is a linear or branched C 1 -C alkyl 4 . In another preferred embodiment, the formula of the quaternary phosphonium halide of the fluid of the invention is X- (Alk 4 P) + , where X is selected from chlorine, bromine and iodine, and Alk is a linear or branched C 1 -C alkyl 4 . In a particular embodiment, Alk is selected from methyl, ethyl, propyl, butyl. In a particular embodiment, the quaternary ammonium halide used in the present invention has the following formula: [C n H 2n + 1 ] 4 N + Br-, where n is 1, 2, 3 or 4.
    [0075] When the alkyl chain is butyl, a greater efficiency has been observed in the reversibility of the Br 2 / Br - redox reaction (see example 4 and figure 6). Thus, in a more preferred embodiment, the alkyl chain is butyl. In a particular embodiment, the ammonium used in the fluid of the invention is hydrated tetrabutylammonium bromide with between 30 and 38 molecules of water.
    [0077] In a third aspect, the invention is directed to an electrolyte comprising the fluid of the first aspect of the invention or the composition of the second aspect of the invention. In a particular embodiment, the electrolyte consists of the fluid of the first aspect of the invention or the composition of the second aspect of the invention.
    [0078] In a fourth aspect, the invention is directed to a cell comprising the fluid of the first aspect of the invention or the composition of the second aspect of the invention, and at least one electrode.
    [0080] The electrode can be selected by the person skilled in the art according to his needs, according to the general knowledge of the art. For example, they can be metallic electrodes, such as copper or platinum electrodes, or modified glassy carbon electrodes.
    [0081] In a fifth aspect, the invention is directed to the use of the fluid of the first aspect of the invention or the composition of the second aspect of the invention, in electrochemical reactions or in energy applications.
    [0083] As demonstrated in Example 3, the fluid and the composition of the invention are capable of encapsulating bromine and thus achieving a reversible process. Thus, the invention is also directed to the use of the fluid of the first aspect of the invention or the composition of the second aspect of the invention, to encapsulate substances. Preferably the substances are polar substances.
    [0085] As demonstrated in Example 5, the fluid of the invention interacts strongly with water and thus prevents oxidation of the platinum electrode. In example 6, it is shown that the fluid of the invention can also act as an electrochemical medium, inhibiting the corrosion of copper electrodes in water in the presence of chloride ions. This new fluid avoids the oxidation of the copper surface and its consequent dissolution, since it restricts the mobility of both the water molecules and the chloride ions, preventing the formation of soluble charged species (CuCh-). Thus, this new fluid would allow the exploitation of cathodic (reduction) processes in electrochemical cells in which the stability of the copper and alloy electrodes is essential.
    [0087] Thus, in a particular embodiment, the invention relates to the use of the fluid of the invention to inhibit the deterioration of electrodes, in particular in electrochemical cells. In a more particular embodiment, the deterioration of the electrodes is due to oxidation or corrosion.
    [0088] The invention also relates to a process for the preparation of the fluid of the invention or of the composition of the invention that comprises mixing a quaternary ammonium salt or a quaternary phosphonium salt with water in quantities to obtain a concentration range of between 2 m and 30 m when it comes to the fluid, and in a concentration range between 0.6 m and 1.99 m if it is the composition.
    [0089] To prepare the mixture it may be necessary to stir, the person skilled in the art knows different stirring methods that can be used in this process depending on the quantities that are prepared, for example magnetic stirring or mechanical stirring.
    [0091] The following examples serve to illustrate the invention and are in no way limiting it.
    [0093] Materials and methods
    [0095] Potassium bromide (KBr), potassium chloride (KCl), tetramethyl ammonium bromide (TMABr, 98%), tetraethyl ammonium bromide (TEABr, 98%), tetrapropyl ammonium bromide (TPABr, 99%), tetrabutyl chloride ammonium (TBACl, 98%) were purchased from Sigma. Tetrabutyl ammonium bromide (TtBABr,> 98%) was purchased from TCI. Graphite nanoplatelets (2299 GNP) were purchased from Asbury. Carbon-adsorbed Pt nanoparticles (Pt / C) (20%) was purchased from Johnson Matthey. Solutions of the different ammonium and potassium salts were prepared by dissolving the particular salt in Milli-Q grade water.
    [0097] Electrochemical experiments were carried out in a computer controlled potentiostat (Autolab 201A) at room temperature using a conventional three electrode cell with a saturated aqueous solution of nitrogen or hydrogen depending on the experiment. A Pt wire was used as a counter electrode and a silver / silver chloride (Ag / AgCl) electrode as a reference electrode. A glassy carbon electrode (GCE, 3 mm diameter) modified with graphite nanoplates or with Pt / C (20%) (Pt content of 14 p, g cm-2) was used as the working electrode. Before use, the glassy carbon electrode was mechanically polished with aqueous suspensions of alumina powder (0.05 µm) and rinsed with Mill-Q water and acetone and allowed to dry under nitrogen. For the experiments that demonstrate the anticorrosive properties of our supramolecular fluid, a copper wire was used as a working electrode. The cyclic voltammograms were carried out in a solution of either a quaternary ammonium salt or a potassium salt at room temperature with a scan rate of 50 mV / s and chronoamperometry with the copper electrode applying 0.3 V.
    [0098] DSC measurements were carried out using a TA Instruments Q200 system. Adiabatic compressibility data were obtained from ultrasound velocity and density measurements (~ 3 MHz) recorded with a Anton Paar DSA 5000 calibrated with water and dry air. Specific heat was measured on a Setaram Micro DSC-III, also calibrated with water. Thermal conductivity measurements were made at room temperature under ambient pressure, using the omega-3 method, in a configuration as described in C. López-Bueno, D. Bugallo, V. Leboran, F. Rivadulla, Phys. Chem. Chem. Phys. 2018, 20, 7277. A small amount of solution (1 | il) was used for each measurement, to avoid the effect of convective flows. All measurements were repeated at least three times, for reproducibility. Raman spectra were measured in solid state under ambient conditions with a Renishaw Raman model InVia Reflex spectrometer using a laser wavelength of 514 nm. The samples were transferred from the electrode to a glass substrate for measurement. UV-vis spectra were performed in quartz cuvettes with a Perkin Elmer Lambda 25 UV / Vis spectrometer at ambient conditions.
    [0100] Example 1
    [0102] A series of solutions were prepared in deionized water with different concentrations of TtBABr, from 0.2 m to 18 m. The calorimetric measurements (DSC) of these solutions show that the behavior up to ~ 0.6 m is similar to that of pure water, with an exothermic peak at the ice formation temperature and an endothermic peak at the melting temperature at 0 ° C. . At [TtBABr]> 0.6 m, the ice peaks are progressively suppressed until almost completely disappeared at 1.8 m. At this concentration, exothermic / endothermic peaks appear characteristic of the formation / fusion ("melting") of the clathrate hydrate crystal lattice. The values obtained for the formation temperature is -8 ° C (265 K) and the melting temperature is 9 ° C-12 ° C (282 K-286 K), and the value obtained for the enthalpy of fusion is AHmelting = 202 J / g. By comparing the area of the endothermic peaks at 0 ° C with that of pure water, the fraction of free water (available to form ice) is extracted from each solution. At 1.8 m, less than 1% of the water molecules are available to form ice, while no free water is detected in the 2 m solution or at concentrations above it (see figure 1). Thus, calorimetric experiments confirm that the mixture of tetrabutyl ammonium bromide and water at concentrations equal to or greater than 2 m, is in a liquid state in which all the water molecules are not free and They are found participating in a structure similar or comparable to that of a solid clathrate hydrate at low temperature.
    [0104] A similar behavior with respect to the absence of free water to form ice, the similar variation in thermal conductivity, compressibility, heat capacity and thermal diffusivity has been observed in solutions of tetrabutylammonium phosphonium in a concentration range between 1-3 m.
    [0106] Example 2
    [0108] A series of solutions with different concentrations of TtBABr, from 0.2 m to 18 m, were prepared in deionized water and their adiabatic compressibility (K) was studied, which were compared with that of pure water (see figure 2a).
    [0110] Thermal contraction makes most liquids less compressible as temperature decreases. However, water shows minimal compressibility at -330 K, with a rapid rise below this temperature due to hydrogen bonding. (LB Skinner, CJ Benmore, JC Neuefeind, JB Parise, J. Chem. Phys 2014 , 141, 214507.) Considering that the energy of water can be minimized through this network of hydrogen bridges, the dependence of adiabatic compressibility (K) with temperature is dominated by temperature and structural fluctuations, above and below the minimum value of the same, respectively (D. Schlesinger, KT Wikfeldt, LB Skinner, CJ Benmore, A. Nilsson, LGMM Pettersson, The Journal of Chemical Physics 2016 , 145, 084503). A minimum at -330 K is also observed in the heat capacity (Cp) of water because hydrogen bonds can store a significant amount of energy. Consequently, any long-range modification of the hydrogen bond network of liquid water by hydrophobic solvation should be reflected in the magnitude and temperature dependence of K and Cp.
    [0112] The studies carried out show that the dissolution of TtBABr in water actually produces a rapid decrease in K and heat capacity Cp (see figure 2b), and the suppression of the minimum in the temperature dependence of both magnitudes. In particular, the decrease in K at low temperatures suggests that the structural fluctuations that dominate K (T <Tmin) in the water are progressively replaced by temperature fluctuations, as [TtBABr] increases. Cp also decreases as [TtBABr] increases, reflecting the suppression of the contribution of hydrogen bonds to low temperature energy storage. However, the negative dCp / dT coefficient up to ~ 3 m demonstrates that the translation and rotation modes (the main contributors to Cp above ambient temperature in liquid water) are largely suppressed at these TtBABr concentrations (at least up to 340 K). On the other hand, K increases again with increasing [TtBABr], and the characteristic variations of dK / dT> 0 and dCp / dT> 0 of molecular liquids are recovered. [TS Banipal, SK Garg, JC Ahluwalia, The Journal of Chemical Thermodynamics 1991 , 23, 923.] Our studies show that both K (293 K) and dCp / dT (293 K) present a minimum in [TtBABr] -1.4- 2.2 m (see figure 2c). The thermal diffusivity, a = k / (pCp) also shows a minimum in the same region as K. The extent and strength of hydrogen bonds is decisive in the transfer of energy in liquid water, through the coupling of the -OH excitations on various H 2 O molecules. The reduction of a is much greater than expected based on purely local coordination, and further supports the fact that the hydrophobic solvation of TtBA + modifies the hydrogen bonding structure of the water in the network, beyond the most immediate molecular environment. Cooling the solution 1.8 m below the solid clathrate formation temperature TtBABrD32H2O does not recover a high value of thermal conductivity as in crystalline ice. This suggests a poor long-range order, with orientation changes between supramolecular assemblages, or movements of the TtBA + chains within the water boxes (or a combination of both). This situation is more like a liquid-glass transition than a true crystallization (as in pure ice, for example) where new and stronger long-range bonds are formed from a disordered liquid.
    [0114] Example 3
    [0116] A) The cyclic voltammograms (in a potential window between 1.0 and 1.4 V) obtained using TtBABr and KBr as electrolytes, both at the same concentration (2 m) at room temperature and with a sweep speed of 50 mV / s, using a vitreous carbon electrode (GCE, 3 mm in diameter) modified with graphite nanoplates as the working electrode. While in KBr the oxidation of Br "to Br 2 is totally irreversible with the formation of the potassium salt of Br 3 " (yellow solid) that comes off the electrode and falls to the bottom of the electrochemical cell, in TtBABr the oxidation is totally reversible (ia / ic ~ 1; being ia the anodic current and ic the cathodic current) allowing the potential window to be expanded to 1.4 V in the absence of the formation of the yellow solid (KBr 3 ), see figure 3. The use of bromide of tetrabutylammonium As an electrolyte, it allows the potential window to be extended from 0.7 to 1.4 V thanks to the fact that the redox process is totally reversible.
    [0117] B) Cyclic voltammograms (in a potential window between 1.0 and 1.4 V) of TtBABr solutions in water as electrolyte were performed at different concentrations (from 0.2 m to 3.5 m) at room temperature and with a speed scanning of 50mV / s, using a vitreous carbon electrode (GCE, 3 mm in diameter) modified with graphite nanoplates as the working electrode. The values obtained are shown in figure 4. The experiment shows that the oxidation of Br- to Br 2 is highly reversible for concentrations equal to or greater than 0.6 m, for which the value of anodic and cathodic increases with concentration and the quotient between them (ia / ic) is practically 1.
    [0118] C) RAMAN spectroscopy measurements (between 100 and 800 cm-1 at a wavelength of 514 nm) were made of the surface of each of the working electrodes after they were used in the voltammetry studies, described in the Example 3B, using TtBABr as electrolyte at different concentrations (0.2 m-3.5 m). The spectra show the presence of a peak (160 cm-1) of tribromomide (Br 3 -) only at low concentrations of TtBABr (0.2 m). In this experiment, above a concentration of 0.6 m the Br 3 - peak is no longer observed, because in TtBABr at high concentrations the Br 2 / Br- redox process becomes reversible, inhibiting the formation of tribromide (Br 3 -), see figure 5.
    [0119] The tetrabutylammonium cation is capable of inhibiting at high concentrations (ie 0.6 m) the formation of the tribromide ion that is formed by the attack of an electrochemically formed Br- to Br 2 ion.
    [0121] Example 4
    [0123] Cyclic voltammograms were performed (in a potential window between 1.0 and 1.4 V) using as electrolyte solutions of different quaternary ammonium bromides with different chains (methyl (n = 1), ethyl (n = 2), propyl ( n = 3) and butyl (n = 4)) in water at the same concentration (2 m) at room temperature and with a scanning speed of 50 mV / s, using a glassy carbon electrode (GCE, 3 mm diameter) modified with graphite nanoplates. It is observed that the anodic faradic current at positive potentials (> 1.2 V) associated with the formation of Br 3 - increases as the number of carbons in the alkyl chain decreases (see figure 6). The comparison of these voltammograms shows, therefore, that the reversibility of the oxidation of Br- to Br 2 depends on the size of the alkyl chain, being maximum (ia / ic ~ 1; where ia is the current anodic and i c the cathodic current) for butyl (n = 4). And only the tetrabutylammonium cation is capable of inhibiting the formation of Br 3- at high potentials (ie> 1.2, shaded area) while presenting the best reversibility (i a / i c ~ 1).
    [0125] Example 5
    [0127] The oxidation of Pt (0) in water to positive potentials, that is, Pt H 2 O ^ Pt-OH H + + e- (and its reverse reduction reaction) is a well known process [S. Gilman, Electrochimica Acta 1964 , 9, 1025.] To test whether the supramolecular liquid structure restricts the participation of water molecules in the redox process that occurs on a Pt surface, the cyclic voltammogram was performed (in a potential window between -6.6 and 0.6 V) of Pt on carbon nanoparticles (Pt / C, 20%) supported on a vitreous carbon electrode (GCE, 3 mm in diameter) using as electrolyte an aqueous solution of TtBABr (2 m) with a scanning speed of 50 mV / s at room temperature and compared with that obtained in KBr used as electrolyte under the same conditions, see figure 7. Pt nanoparticles present the expected electrochemical activity in a hydrogen saturated solution of KBr (2 m), that is, H 2 molecules show reversible adsorption / desorption on the surface of Pt at negative potentials (from ~ -0.6 to 0 V), while H 2 O molecules oxidize the surface of Pt at a potential greater than ~ 0.4 V. The cathodic peak at 0.38 V in the KBr solution corresponds to the reduction of the electrochemically oxidized Pt surface. In contrast, the oxidation of Pt by e1H 2 O is completely inhibited in the aqueous solution of TtBABr (2 m), as reflected in the absence of any measurable faradic current at positive potentials. It is important to note that TtBA + is not blocking the electrode surface, as evidenced by the fact that Pt is still electrochemically active at negative potentials, where hydrogen adsorption / desorption takes place. Therefore, it is the strong interaction between the H 2 O molecules in the compact structure of this supramolecular liquid that limits their reactivity.
    [0129] Example 6
    [0131] A) The electrochemical applications of various non-noble metals such as Cu are severely limited by their stability in an aqueous environment, especially in the presence of chloride ions (Cl-), due to corrosion [Y. Wang, B. Liu, X. Zhao, X. Zhang, Y. Miao, N. Yang, B. Yang, L. Zhang, W. Kuang, J. Li, E. Ma, Z. Shan, Nature Communications 2018 , 9, 1; Y. Qiang, S. Fu, S. Zhang, S. Chen, X. Zou, Corrosion Science 2018 , 140, 111]. For To investigate whether our supramolecular fluid ([TtBACl]> 2m) can reduce the corrosion of such metals when it acts as an electrolyte, the electrochemical properties of a copper wire (working electrode) in a three-electrode configuration using Ag / AgCl as reference electrode and a Pt wire as counter electrode and were compared with those obtained for an aqueous solution of KCl at the same concentration and conditions (nitrogen atmosphere, room temperature and scanning speed of 50 mV / s). The corrosion of Cu is chemically complex and, in addition to oxidation to copper oxides (Cu 2 O), an additional two-step process in the presence of Cl- is known. In this case, a CuCl film grows on the surface of the electrode, according to AR Langley, M. Carta, R. Malpass-Evans, NB McKeown, JHP Dawes, E. Murphy, F. Marken, Electrochimica Acta 2018 , 260, 348 .
    [0133] Cu (s) Cl- (aq) or CuCl (s) e-
    [0134] and then forms a soluble species of chloro-cuprate (I):
    [0136] CuCl (s) Cl- or CuCl 2 - (aq)
    [0138] The cyclic voltammogram of a Cu wire obtained in a KCl solution (2 m) shows that the corrosion of Cu takes place through a redox process that involves the oxidation of Cu (0) to Cu (I) at a potential of ~ 0 V with a separation between the anodic and cathodic peak of ~ 0.216 V (AE = Ea-Ec), see figure 8. The low coulombic efficiency of the process (ratio between the anodic and cathodic peak much greater than 1, (ia / ic) ~ 2.42) confirms that part of the Cu atoms are irreversibly oxidized to CuCh- (aq) that is lost moving away from the surface of the electrode, also forming Cu 2 O in water that is deposited on the electrode. The formation and loss of CuCh- (aq) is in accordance with the fact that at a potential greater than 0.2 V the current remains positive, indicating that new Cu atoms appear continuously on the electrode surface and oxidize to positive potentials. When comparing the cyclic voltammogram of a Cu wire in a TtBACl solution (2 m) with that obtained in KCl (2 m), it is observed that the corrosion process that occurs in KCl is now inhibited in our supramolecular fluid. In its place appears a new redox process for the oxidation of Cu (0) to Cu (I) at a potential of ~ -0.52 V (AE = Ea-Ec ~ 1,162 V) and at a lower current density in which Cu (I) is now stabilized against the reduction in the structure that forms our supramolecular fluid, see figure 8. In this process it is also observed that the formation and loss of CuCl 2 - (aq) it is suppressed since the current at a potential of 0.2 V is now negative as the potential decreases after oxidation.
    [0140] B) Chronoamperometric experiments were carried out at 0.3 V and the solutions used as electrolytes were analyzed. While no change is observed for the aqueous solution of TtBACl (2 m) after applying a potential of 0.3 V for 300 seconds, for the potassium solution that is initially colorless after only 90 seconds a color change is observed in the dissolution to brown as a result of copper corrosion, which is consistent with the presence of a band below 300 nm in its ultraviolet-visible spectrum, see figure 9.
    [0141] C) RAMAN spectroscopy measurements (in the range of 100 to 1000 cm "1 at a wavelength of 514 nm) were made of the surface of the Cu electrodes after chronoamperometric experiments (0.3V), according to example 6B , using TtBACl and KCl as electrolyte at the same concentration (2 m), see figure 10. Optical images of the analyzed areas were also obtained (scale: 30 | im). The electrode surface remains completely intact after applying 0.3V for 300 seconds in the presence of TtBACl (only bands related to the presence of the TtBA + cation, * are observed), while in potassium chloride after only 90 seconds the presence of copper oxide and copper chloride is observed as a consequence corrosion, which is consistent with the presence of a blue coating in the analyzed images.
    权利要求:
    Claims (12)
    [1]
    1. Supramolecular fluid stable under atmospheric conditions characterized in that it comprises a quaternary ammonium halide or a quaternary phosphonium halide, with a concentration equal to or greater than 2 m in an aqueous solution.
    [2]
    2. Fluid according to claim 1, wherein the concentration is between 2 m and 30 m.
    [3]
    3. Fluid according to any of the preceding claims, wherein the formula of the quaternary ammonium halide is X- (Alk 4 N) + , where X is selected from chlorine, bromine iodine, and Alk is a linear or branched C 1 -C alkyl 4 .
    [4]
    4. Fluid according to any of the preceding claims, where the formula of the quaternary phosphonium halide is X- (Alk 4 P) + , where X is selected from chlorine, bromine iodine, and Alk is a linear or branched C 1 -C alkyl 4 .
    [5]
    5. Composition comprising a quaternary ammonium halide or a quaternary phosphonium halide in a concentration equal to or greater than 0.6 m and equal to or less than 1.99 m in aqueous solution.
    [6]
    6. Electrolyte that compensates the fluid described in claims 1-4 or the composition described in claim 5.
    [7]
    7. Cell comprising the fluid described in claims 1-4 or the composition described in claim 5, and at least one electrode.
    [8]
    8. Use of the fluid according to any of claims 1-4 or of the composition according to claim 5, in electrochemical reactions or in energy applications.
    [9]
    9. Use of the fluid according to any of claims 1-4 or of the composition according to claim 5, to encapsulate substances.
    [10]
    10. Use according to claim 9, wherein the encapsulated substances are polar molecules.
    [11]
    11. Use of the fluid according to any of claims 1-4 or of the composition according to claim 5, to inhibit the deterioration of electrodes.
    [12]
    12. Use according to claim 11, wherein the deterioration of the electrodes is due to oxidation or corrosion.
    类似技术:
    公开号 | 公开日 | 专利标题
    JP6766093B2|2020-10-07|Highly soluble iron hexacyanide
    Takechi et al.2015|A highly concentrated catholyte based on a solvate ionic liquid for rechargeable flow batteries
    ES2539957T3|2015-07-07|Method of storing electrical energy in ionic liquids
    TWI286854B|2007-09-11|Proton conducting mediums for electrochemical devices and electrochemical devices comprising the same
    Long et al.2003|Spectroelectrochemical characterization of nanostructured, mesoporous manganese oxide in aqueous electrolytes
    ES2666853T3|2018-05-08|Metal-air cell with an ion exchange material
    JP2007500429A|2007-01-11|Ionic liquids and ionic liquid acids with high temperature stability for fuel cells and other high temperature applications, production methods and batteries using them
    Kanamura et al.2002|Electrochemical behavior of al current collector of rechargeable lithium batteries in propylene carbonate with licf3 so 3, li | 2 n, or li | n
    JP6035345B2|2016-11-30|Aluminum-based metal-air battery
    KR20070114323A|2007-11-30|Molten salt composition and use thereof
    Wu et al.2013|Electrochromic properties of nanostructured tungsten oxide films prepared by surfactant-assisted sol–gel process
    Yoshizawa-Fujita et al.2014|A plastic electrolyte material in a highly desirable temperature range: n-ethyl-N-methylpyrrolidinium bis | amide
    Kolosnitsyn et al.2008|Physicochemical and electrochemical properties of sulfolane solutions of lithium salts
    ES2564413T3|2016-03-22|Method of synthesis of a metallic foam, metallic foam, its uses and device comprising a metallic foam of this type
    Yamamoto et al.2019|Room-temperature fluoride shuttle batteries based on a fluorohydrogenate ionic liquid electrolyte
    ES2797556B2|2021-04-20|SUPRAMOLECULAR FLUID
    Rath et al.2019|Hybrid electrolyte enables safe and practical 5 V LiNi 0.5 Mn 1.5 O 4 batteries
    WO2012074089A1|2012-06-07|Ionic gelling agent, gel, process for production of gel, and crosslinking agent
    Fischer et al.2018|Synthesis and physicochemical characterization of room temperature ionic liquids and their application in sodium ion batteries
    Zhang et al.2005|Hydrophobic ionic liquids based on the 1-butyl-3-methylimidazolium cation for lithium/seawater batteries
    WO2022053735A1|2022-03-17|Supramolecular fluid
    Maheshwaran et al.2020|Effect of Mg | 2 concentration on structural and electrochemical properties of ionic liquid incorporated polymer electrolyte membranes
    Shi et al.2013|Bis-quaternary ammonium cation-based organic ionic plastic crystals: plastic crystal behaviour and ionic liquid properties above melting points
    Uzundal et al.2017|Lyotropic liquid crystalline mesophase of sulfuric acid–nonionic surfactant stabilizes lead | oxide in sulfuric acid concentrations relevant to lead acid batteries
    Owe et al.2010|Electrochemical behavior of iridium oxide films in trifluoromethanesulfonic acid
    同族专利:
    公开号 | 公开日
    ES2797556B2|2021-04-20|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2020-12-02| BA2A| Patent application published|Ref document number: 2797556 Country of ref document: ES Kind code of ref document: A1 Effective date: 20201202 |
    2021-04-20| FG2A| Definitive protection|Ref document number: 2797556 Country of ref document: ES Kind code of ref document: B2 Effective date: 20210420 |
    优先权:
    申请号 | 申请日 | 专利标题
    ES202030929A|ES2797556B2|2020-09-14|2020-09-14|SUPRAMOLECULAR FLUID|ES202030929A| ES2797556B2|2020-09-14|2020-09-14|SUPRAMOLECULAR FLUID|
    [返回顶部]