Process for producing an aluminium ion-conducting polymer, aluminium ion-conducting polymer and use thereof

Abstract

The invention relates to a process and to the use thereof for producing an aluminium ion-conducting polymer, at least having the following steps: a) providing at least one aluminium salt; an organic compound capable of forming an ionic liquid together with the at least one aluminium salt; and a polyacrylonitrile (PAN)-based polymer; b) producing an ionic liquid by mixing the at least one aluminium salt and the organic compound; c) adding the PAN-based polymer to the ionic liquid and thermal treatment with exclusion of air at a temperature in the range from 100°C to 230°C. The invention further relates to an aluminium ion-conducting polymer and to the use thereof.

Description

[0001] Process for producing an aluminum ion-conducting polymer, aluminum ion-conducting polymer and its use

[0002] The invention relates to a process for producing an aluminum ion-conducting polymer, the aluminum ion-conducting polymer and its use.

[0003] Currently, aluminum batteries use ionic liquids (ILs) and deep eutectic solutions (DES) based on aluminum chloride (AlCl3) as electrolytes. These electrolytes contain chloroaluminate complexes, which are considered extremely aggressive due to their chemical nature. Due to this property, there is a risk of leakage of the ionic liquids and the resulting corrosion. This risk can be reduced by polymerizing these liquids.

[0004] Currently, a gelling agent is added to liquid electrolytes (IL, DES) to create a gel electrolyte. Amide-based monomers or polymers such as acrylamide or polyamide have proven to be effective gelling agents [1, 2]. However, such gel electrolytes are usually too liquid, making a separator indispensable, or the preparation of the polymer gel electrolyte requires the use of harmful solvents.

[0005] In studies, the production of a PAN-containing gel electrolyte membrane was demonstrated [3]. The disadvantage is that the resulting membrane cannot be used directly in electrochemical cells. This is only possible through a subsequent process step: impregnation in an ionic liquid, which enables the membrane to electrochemically deposit aluminum.

[0006] The object of the invention is therefore to provide a process for producing an aluminum ion-conducting polymer and an aluminum ion-conducting polymer which has sufficient stability for use in aluminum batteries without an additional separator and whose production does not require harmful solvents.

[0007] According to the invention, the object is achieved by a method according to independent claim 1 and an aluminum ion-conducting polymer according to independent claim 9. Advantageous embodiments of the invention are specified in the dependent claims.

[0008] A first aspect of the invention relates to a process for producing an aluminum ion-conducting polymer, comprising at least the steps of: a) providing at least one aluminum salt; an organic compound capable of forming an ionic liquid with the at least one aluminum salt; and a polyacrylonitrile (PAN)-based polymer; b) producing an ionic liquid by mixing the at least one aluminum salt and the organic compound; c) adding the PAN-based polymer to the ionic liquid and subjecting it to a temperature treatment in the absence of air at a temperature in the range from 100°C to 230°C.

[0009] In embodiments, the method according to the invention is carried out in the order of steps a), b) and c).

[0010] Advantageously, the process according to the invention allows for the simple and large-scale production of an aluminum ion-conducting polymer without the use of harmful solvents. The process according to the invention also advantageously allows for the production of an aluminum ion-conducting polymer that is capable of electrochemically depositing aluminum and is thus suitable for a variety of applications. Furthermore, the production of the aluminum ion-conducting polymer can be easily integrated into existing manufacturing processes and technologies. The process also advantageously enables the targeted adjustment of the properties of the aluminum ion-conducting polymer, such as ionic conductivity, elasticity, and / or strength, to suit the specific application of the polymer.Furthermore, an aluminum ion-conducting polymer produced in this way advantageously has a higher viscosity than known gel electrolytes, thus eliminating the need for separators. Furthermore, the aluminum ion-conducting polymer produced by the process is directly usable and capable of electrochemically depositing aluminum. Further process steps, such as impregnating the aluminum ion-conducting polymer in an ionic liquid, are not necessary to achieve the functionality (electrochemical deposition of aluminum). Thus, the process according to the invention enables a simpler production of an aluminum ion-conducting polymer compared to the prior art by eliminating process steps.

[0011] In the following, the term "a" is always understood to mean "at least one." Thus, an aluminum salt, an organic compound, a PAN-based polymer, etc., also means at least one aluminum salt, at least one organic compound, at least one PAN-based polymer, etc.

[0012] An aluminum salt within the meaning of the invention includes aluminum halides, aluminum sulfonates, such as aluminum trifluoromethanesulfonate Al(OTf)3; aluminum nitrate Al(NO3)3, aluminum sulfate Al2(SO4)3, and aluminum phosphate AlPO4, and / or mixtures thereof. Preferably, the at least one aluminum salt is an aluminum halide, such as AlF3, AlCl, AlBr3, Al13, and / or a mixture of aluminum salts.

[0013] Conveniently, an organic compound also includes organic salts. Organic salts include pyridinium halides, ammonium halides, imidazolium halides, and / or mixtures thereof. In embodiments, the organic compound is selected from ionic liquids, such as 1-butylpyridinium chloride ([BP]Cl), trimethylphenylammonium chloride (TMPAC), 1-butyl-3-methylimidazolium halide ([BMIm]X), 1-ethyl-3-methylimidazolium halide ([EMIm]X), triethylamine hydrohalide ([Et3N]HX), 4-ethylpyridine, 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIm]OTf), and / or mixtures thereof. X is selected from the halogens F, Cl, Br, and I.

[0014] In embodiments, the organic compound is selected from urea, acetamide, caprolactam, and mixtures thereof.

[0015] In embodiments, the preparation of an ionic liquid in step b) is carried out by gradually adding the at least one aluminum salt to the organic compound. This advantageously allows the exothermic reaction to be controlled.

[0016] In some embodiments, step b) is carried out in the absence of air. The term "air exclusion" refers to the use of an atmosphere with an oxygen content of no more than 10 ppm and / or a water content of no more than 10 ppm. In some embodiments, step b) and / or step c) is carried out in an inert gas atmosphere, in particular a nitrogen or argon atmosphere.

[0017] The ionic liquid prepared in step b) may contain undissolved residues of the at least one aluminum salt.

[0018] In step c), a PAN-based polymer is added to the ionic liquid prepared in step b). This initially creates a suspension of the ionic liquid and undissolved residues of the at least one aluminum salt and the PAN-based polymer.

[0019] In some embodiments, the PAN-based polymer is added to the ionic liquid in step c) under exclusion of air. In further embodiments, the PAN-based polymer is added in powder form. It is advantageous if the PAN-based polymer powder has a particle size in the range of 50 pm to 100 μm. Furthermore, in step c), a thermal treatment is carried out under exclusion of air at a temperature in the range of 100 °C to 230 °C.

[0020] Advantageously, the heat treatment in step c) dissolves the solid components in the resulting suspension, such as any undissolved residues of the at least one aluminum salt and the PAN-based polymer. Furthermore, an aluminum ion-conducting polymer, in particular an elastomer, is advantageously formed, the degree of which can be adjusted by selecting the temperature and duration of the heat treatment. Higher temperatures and longer times lead to an increase in the degree of which can be crosslinked.

[0021] The degree of crosslinking refers to the ratio of the number of crosslinked building blocks to the total number of building blocks present. Experimentally, the degree of swelling in a solvent can be determined as a measure of the degree of crosslinking of a polymer, based on DIN ISO 1817.

[0022] The melt volume flow rate (also known as melt flow index) of the formed polymer can be determined in accordance with ISO 1133 and is used to characterize the flow behavior (molding compound test) of a thermoplastic under certain pressure and temperature conditions, if necessary under protective gas, and allows conclusions to be drawn about the degree of polymerization, i.e. the average number of monomer units in a molecule.

[0023] Temperatures above 230 °C should be avoided in step c) as these lead to decomposition of the polymer formed.

[0024] In some embodiments, the heat treatment lasts between 1 and 120 minutes. The duration of the heat treatment depends on the thickness of the aluminum ion-conducting polymer formed. For example, a duration of 30 to 120 minutes is advantageous if the aluminum ion-conducting polymer has a thickness of approximately 2 cm to achieve the desired degree of crosslinking. For thicknesses below 2 cm, e.g., for an aluminum ion-conducting polymer present as a coating, a duration of 1 to 10 minutes is advantageous.

[0025] In embodiments, the heat treatment in step c) is carried out at a temperature in the range of 120°C to 140°C for a duration of 10 to 60 minutes. This advantageously produces an aluminum ion-conducting polymer, which is present as a clear, viscous solution and can be used as a starting material for the production of PAN nanofibers and thus carbon nanofibers. In preferred embodiments, the PAN-based polymer is polyacrylonitrile (PAN) or a PAN-based copolymer with a PAN content in the range of 50 wt.% to 99 wt.%.

[0026] A PAN-based copolymer with a proportion of 50 wt.% to 99 wt.% PAN means a copolymer which contains the monomer acrylonitrile and at least one other monomer.

[0027] In embodiments, a PAN-based copolymer has a PAN content in the range of 60 wt% to 99 wt%, preferably in the range of 70 wt% to 99 wt%, more preferably in the range of 80 wt% to 99 wt%, and most preferably in the range of 90 wt% to 99 wt%.

[0028] Advantageously, the ionic conductivity and strength of the aluminum ion-conducting polymer are adjusted by the PAN-based polymer and its proportion in the aluminum ion-conducting polymer, so that even with small proportions of the PAN-based polymer in the range of a few wt.% and at a suitable treatment temperature, sufficient strength and good ionic conductivity can be achieved.

[0029] In preferred embodiments, in step b) the aluminum salt and the organic compound are mixed together in a molar ratio in the range of 1:1 to 4:1.

[0030] Advantageously, the acidity can be adjusted by varying the aluminum salt content, thus enabling the adaptation of the produced aluminum ion-conducting polymer for battery applications as an electrolyte.

[0031] In preferred embodiments, in step b) the aluminum salt and the organic compound are mixed in a molar ratio of 2:1 to 4:1.

[0032] This advantageously increases the solubility limit and compensates for the loss of the negative dimer [AhCb]' during the reaction with the PAN-based polymer in the ionic liquid. This also advantageously increases the proportion of active complex ions in the formed polymer and thus the cell capacity, making such a polymer suitable for battery applications.

[0033] In preferred embodiments, in step c) the PAN-based polymer is added in a molar ratio of 0.1:1 to 2:1 based on the organic compound.

[0034] This advantageously increases the solubility of the at least one aluminum salt and adjusts the acidity in the mixture. The PAN-based polymer reacts with the negative dimer [AhCl], forming AlCl, which in turn reacts with the undissolved aluminum salt to form [AhCl]. In embodiments, the proportion of the at least one aluminum salt in the suspension produced in step c) is at least 50 mol%. In further embodiments, the proportion of the at least one aluminum salt in the suspension produced in step c) is in the range from 50 mol% to 70 mol%.

[0035] In embodiments, the proportion of the organic compound in the suspension produced in step c) is in the range from >0 mol% to 50 mol%. In further embodiments, the proportion of the PAN-based polymer in the suspension produced in step c) is in the range from >0 mol% to 50 mol%.

[0036] In embodiments, in step c), a mixture of a PAN-based polymer and at least one aluminum salt with a molar ratio in the mixture in the range of greater than 0:1 to 1:1 is added to the ionic liquid, and a temperature treatment is carried out in the absence of air at a temperature in the range of 100°C to 230°C. This is advantageous if, in step b), the aluminum salt and the organic compound are mixed in a molar ratio of 2:1.

[0037] In preferred embodiments, after step c) a forming takes place as step d).

[0038] Advantageously, the aluminum ion-conducting polymer thus produced is converted into a form that can be used for a variety of applications, preferably into a polymer film or a polymer layer.

[0039] In some embodiments, the forming process in step d) is carried out in such a way that a polymer layer is formed. This can be carried out by extrusion, doctor blade coating, rolling, film casting, pressing, or nozzle application. The forming process is to be selected depending on the degree of crosslinking achieved by the temperature treatment in step c) and thus the viscosity. For example, polymers formed in step c) with a lower degree of crosslinking, which are present as viscous liquids, can be easily formed into a polymer layer by film casting, extrusion, doctor blade coating, etc. Polymers formed in step c) with higher degrees of crosslinking and thus increased viscosities can be formed into a polymer layer, for example, by rolling, calendering, or pressing. The possible forming processes and their selection depending on the viscosity of the material to be formed are known in principle to those skilled in the art.

[0040] In embodiments, the polymer formed in step c) can be applied to a film, a nonwoven, or a woven fabric. This is advantageous, for example, when the forming process is carried out by pressing or rolling and can prevent the polymer to be formed from adhering to the pressing tools or rollers. In further embodiments, a further film, a further nonwoven, or a further woven fabric can be applied to the polymer applied to a film, a nonwoven, or a woven fabric, so that the polymer is embedded between films, nonwovens, and / or woven fabrics.

[0041] In embodiments, step d) is carried out under exclusion of air.

[0042] In embodiments, step d) takes place at a temperature in the range of 80°C to 130°C. This is particularly advantageous if the heat treatment in step c) was carried out at a temperature in the range of 150°C to 230°C. Such a heat treatment leads to an increased degree of crosslinking and, associated with this, to increased viscosity and strength of the formed polymer, making subsequent forming more difficult. In this case, it is advantageous to carry out the forming at a temperature in the range of 80°C to 130°C to reduce the viscosity of the polymer and increase formability.

[0043] In preferred embodiments, the temperature treatment in step c) is carried out at a temperature in the range of 100 °C to 150 °C.

[0044] This advantageously dissolves solid components, such as any undissolved residues of the at least one aluminum salt and PAN-based polymer. Furthermore, a partially or incompletely crosslinked aluminum ion-conducting polymer is formed, which is in the form of a viscous liquid and is thus flowable and easily deformable.

[0045] In embodiments, a second temperature treatment is carried out as step e) at a temperature in the range of 150 °C to 230 °C.

[0046] This is particularly advantageous if the temperature treatment in step c) is carried out at a temperature in the range of 100 °C to 150 °C. In embodiments, the temperature treatment in step c) is carried out at a temperature in the range of 150 °C to 230 °C, and no second temperature treatment is carried out as step e).

[0047] The second temperature treatment advantageously adjusts the final viscosity and strength of the aluminum ion-conducting polymer for the respective application.

[0048] In embodiments, step e) occurs after step d).

[0049] In embodiments, step e) is carried out for a duration of 1 to 120 minutes. The duration of the heat treatment depends on the thickness of the aluminum ion-conducting polymer formed. For example, a duration of 30 to 120 minutes is advantageous if the aluminum ion-conducting polymer has a thickness of approximately 2 cm in order to achieve a desired degree of crosslinking. For thicknesses below 2 cm, e.g. for an aluminum ion-conducting polymer present as a coating, a duration of 1 to 10 minutes is advantageous. A further aspect of the invention relates to an aluminum ion-conducting polymer consisting of a covalently crosslinked PAN-based polymer and at least one aluminum salt and an organic compound dissolved therein, wherein the molar ratio of the aluminum salt to the organic compound is 1:1 to 4:1, and wherein the molar ratio of the PAN-based polymer to the organic compound is 0.1:1 to 2:1.

[0050] Advantageously, such an aluminum ion-conducting polymer has a higher viscosity than known gel electrolytes, making the use of separators obsolete. Another advantage is that such a polymer does not contain any harmful solvents. Likewise advantageously, such an aluminum ion-conducting polymer as an electrolyte has significantly reduced chemical aggressiveness or corrosiveness compared to liquid electrolytes and enables safe use. Another advantage is that such an aluminum ion-conducting polymer as a polymer electrolyte is less reactive towards water, i.e. the stability of the polymer electrolyte upon contact with water or air is increased. Another advantage is that the aluminum ion-conducting polymer is capable of electrochemically depositing aluminum and conducting aluminum ions or aluminum-containing complex ions, making it suitable for a variety of applications.Furthermore, such an aluminum ion-conducting polymer exhibits good mechanical properties and can be used as a solid electrolyte in the production of flexible and robust electrochemical energy storage devices. Also advantageous is the ability of such an aluminum ion-conducting polymer to widely adjust its properties, such as ionic conductivity, strength, degree of crosslinking, etc., and thus adapt to different applications. Another advantage of such an aluminum ion-conducting polymer is its ability to dissolve, transport, and deposit aluminum ions without the need for impregnation.

[0051] In preferred embodiments, the aluminum ion-conducting polymer has an ionic conductivity in the range of 0.1 mS / cm to 10 mS / cm at a temperature in the range of 10 °C to 40 °C.

[0052] Such an aluminum ion-conducting polymer can advantageously be used as a polymer electrolyte in electrochemical energy storage devices, such as aluminum batteries, and in the electrochemical deposition of aluminum. In preferred embodiments, the molar ratio of the aluminum salt to the organic compound is 2:1 to 4:1.

[0053] Advantageously, by varying the aluminum salt content, the acidity of the aluminum ion-conducting polymer can be adjusted and the battery capacity can be increased in the case of application within an electrochemical energy storage device.

[0054] In embodiments, the aluminum ion-conducting polymer used as an electrolyte has a specific gravimetric capacity in the range of 0.1 mAh / g to 70 mAh / g. This is determined by theoretically calculating the molar amount of the AhXf compound per gram of the aluminum ion-conducting polymer (X = F, Cl, Br, or I).

[0055] A further aspect of the invention relates to the use of an aluminum ion-conducting polymer produced by the process according to the invention as an electrolyte in an aluminum battery, in a process for the electrochemical deposition of aluminum and / or in a process for the production of carbon fibers.

[0056] An aluminum ion-conducting polymer produced by the process according to the invention can be used in embodiments as an electrolyte, preferably as a polymer electrolyte, in electrochemical energy storage devices, e.g. aluminum batteries, in a process for the electrochemical deposition of aluminum and / or in a process for producing carbon fibers, e.g. as a starting material in a process for producing PAN nanofibers and thus carbon nanofibers.

[0057] A further aspect of the invention relates to the use of an aluminum ion-conducting polymer according to the invention as an electrolyte in an aluminum battery, in a process for the electrochemical deposition of aluminum and / or in a process for the production of carbon fibers.

[0058] An aluminum ion-conducting polymer according to the invention can be used in embodiments as an electrolyte, preferably as a polymer electrolyte, in electrochemical energy storage devices, e.g., aluminum batteries, in a process for the electrochemical deposition of aluminum, and / or in a process for producing carbon fibers, e.g., as a starting material in a process for producing PAN nanofibers and thus carbon nanofibers. For the implementation of the invention, it is also expedient to combine the above-described inventive configurations, embodiments, and features of the claims.

[0059] Examples of implementation

[0060] The invention will be explained in more detail below using an exemplary embodiment. The exemplary embodiments relate to a method for producing an aluminum ion-conducting polymer and an aluminum ion-conducting polymer and are intended to describe the invention without limiting it.

[0061] Example 1

[0062] In one embodiment of the process according to the invention for producing an aluminum ion-conducting polymer, at least one aluminum salt, one organic compound, and a PAN-based polymer are provided as a powder in step a). The aluminum salt is AlCh, the organic compound is 1-ethyl-3-methylimidazolium chloride [EMIM]Cl, and the PAN-based polymer is polyacrylonitrile (PAN). In step b), an ionic liquid containing undissolved AlCh residues is prepared from 2.5 mol of AlCh and 1 mol of 1-ethyl-3-methylimidazolium chloride [EMIM]Cl in a glove box under the exclusion of air.

[0063] In step c), 0.5 mol of PAN is added to the prepared ionic liquid under exclusion of air. This creates a suspension of the ionic liquid and undissolved residues of AlCh and PAN. In step c), a temperature treatment at 140 °C for 30 minutes under exclusion of air is carried out, which dissolves the undissolved components and forms an aluminum ion-conducting polymer in the form of a flowable, viscous liquid.

[0064] Subsequently, in step d), the resulting polymer is reshaped by applying the flowable polymer as a polymer film to a surface, e.g., a nonwoven, using a doctor blade. Subsequently, in step e), a second heat treatment takes place at a temperature of 180 °C for a duration of 2 to 10 minutes to adjust the final degree of crosslinking and strength. This results in a solid polymer film that can be used, for example, as a polymer electrolyte in electrochemical energy storage devices. Embodiment 2

[0065] In a further embodiment of the process according to the invention, steps a) and b) are carried out analogously to embodiment 1. In step c), the heat treatment takes place at a temperature of 160 °C for a duration of 30 minutes. The undissolved components dissolve and an aluminum ion-conducting polymer is formed which is no longer flowable. In a subsequent step d), the non-flowable polymer is formed by pressing it between heated platens at a temperature of 130 °C to form a polymer film. In one embodiment, the polymer is applied to a film before pressing and a further film is applied to the polymer to be formed so that the polymer is arranged between two films which prevent the polymer from adhering to the heated platens.

[0066] In a further embodiment, the forming in step d) is alternatively carried out by rolling at a temperature of 120 °C (surface temperature of the rolls) in a calender. Here, too, direct contact and thus adhesion of the polymer to the heated rolls can be prevented by applying the polymer to a film before rolling and applying another film to the polymer, so that the polymer is sandwiched between two films.

[0067] Example 3

[0068] An aluminum ion-conducting polymer was produced using a process according to embodiments 1 and 2. The aluminum ion-conducting polymer consists of a covalently crosslinked PAN-based polymer and at least one aluminum salt and an organic compound dissolved therein, wherein the molar ratio of the aluminum salt to the organic compound is 1:1 to 4:1, and wherein the molar ratio of the PAN-based polymer to the organic compound is 0.1:1 to 2:1.

[0069] For comparison purposes, a polymer was produced using a similar process, but PA6 was added as the polymer instead of PAN. The proportion of PAN and PA6 in the finished polymer is 3 wt.% each.

[0070] The following properties of the polymers produced were determined in comparison: It is evident that the aluminum ion-conducting polymer produced with PAN using the process according to the invention is non-flowable and can therefore be used as a solid electrolyte in battery applications. Due to the sluggish reactions upon contact with air and water, such a polymer electrolyte increases safety in battery applications.

[0071] In comparison, a solid electrolyte with the desired properties and a low polymer content cannot be produced with PA6, as the polymer still exhibits good flow properties. The reaction upon contact with water is also very violent, making it unsuitable for battery applications.

[0072] Example 4

[0073] An aluminum ion-conducting polymer produced using the process from Example 1 is used in an aluminum-graphite battery with a graphite cathode and an aluminum anode as the electrolyte. The electrolyte exhibits a high specific gravimetric capacity of up to 46.5 mAh / g, which is significantly higher than the values ​​known from the prior art. The specific gravimetric capacity is determined by theoretically calculating the molar amount of the AhXf compound per gram of the aluminum ion-conducting polymer (X = F, Cl, Br, or I).

[0074] Example 5

[0075] An aluminum ion-conducting polymer produced by the process according to Example 1 has a specific ionic conductivity of 1.1 mS / cm. To determine whether aluminum or aluminum-containing ion complexes are transported, a pouch cell with aluminum as the positive electrode and copper as the negative electrode with an electrode area of ​​4.2 x 3.0 cm 2 and an aluminum ion-conducting polymer according to Example 1 was used as the electrolyte. The copper electrode was weighed before and after the measurement to determine the weight increase due to the aluminum deposition. Figure 1 shows the chronoamperometric measurement at a current density of 0.5 mA cm 2and the weight gain of the copper electrode are shown. It is clearly visible that aluminum has been deposited on the copper electrode. This measurement demonstrates that the flowing current consists primarily of aluminum-containing ions and that the electrolyte effectively deposits aluminum. The electrolyte's efficiency in dissolving, transporting, and depositing aluminum is over 96%. Cited non-patent literature:

[0076] [1] Liu, Zhidong, et al. "Low-cost gel polymer electrolyte for high-performance aluminum-ion batteries." ACS Applied Materials & Interfaces 13.24 (2021): 28164-28170.

[0077] [2] Mohammad, Amir, et al. "A Flexible Solid-State Ionic Polymer Electrolyte for Application in Aluminum Batteries." ACS Applied Energy Materials 6.5 (2023): 2914-2923.

[0078] [3] Elia, Giuseppe Antonio, et al. "A gel polymer electrolyte for aluminum batteries." Energy Technology 9.8 (2021): 2100208.

Claims

Patent claims 1. A process for producing an aluminum ion-conducting polymer, comprising at least the steps of: a) providing at least one aluminum salt; an organic compound capable of forming an ionic liquid with the at least one aluminum salt; and a polyacrylonitrile (PAN)-based polymer; b) producing an ionic liquid by mixing the at least one aluminum salt and the organic compound; c) adding the PAN-based polymer to the ionic liquid and subjecting it to a temperature in the range from 100°C to 230°C in the absence of air.

2. Process according to claim 1, characterized in that the PAN-based polymer is PAN or a PAN-based copolymer having a PAN content in the range of 50 wt% to 99 wt%.

3. Process according to claim 1 or 2, characterized in that in step b) the aluminum salt and the organic compound are mixed in a molar ratio in the range of 1:1 to 4:

1.

4. Process according to one of claims 1 to 3, characterized in that in step b) the aluminum salt and the organic compound are mixed in a molar ratio of 2:1 to 4:

1.

5. Process according to one of claims 1 to 4, characterized in that in step e) the PAN-based polymer is added in a molar ratio of 0.1:1 to 2:1 based on the organic compound.

6. The method according to any one of claims 1 to 5, characterized in that in step c) a mixture of the PAN-based polymer and the at least one aluminum salt with a molar ratio in the range of greater than 0:1 to 1:1 is added to the ionic liquid and a temperature treatment is carried out in the absence of air at a temperature in the range of 100 °C to 230 °C.

7. Method according to one of claims 1 to 6, characterized in that after step c) a forming takes place as step d).

8. The method according to any one of claims 1 to 7, characterized in that the temperature treatment in step c) is carried out at a temperature in the range from 100 °C to 150 °C.

9. The method according to any one of claims 1 to 8, characterized in that a second temperature treatment as step e) is carried out at a temperature in the range from 150 °C to 230 °C.

10. An aluminum ion-conducting polymer consisting of a covalently crosslinked PAN-based polymer and at least one aluminum salt and an organic compound dissolved therein, wherein the molar ratio of the aluminum salt to the organic compound is 1:1 to 4:1, and wherein the molar ratio of the PAN-based polymer to the organic compound is 0.1:1 to 2:

1.

11. An aluminum ion-conducting polymer according to claim 10, having an ionic conductivity in the range of 0.1 mS / cm to 10 mS / cm at a temperature in the range of 10 °C to 40 °C.

12. An aluminum ion-conducting polymer according to claim 10 or 11, characterized in that the molar ratio of the aluminum salt to the organic compound is 2:1 to 4:

1.

13. Use of an aluminum ion-conducting polymer produced by a process according to any one of claims 1 to 9 as an electrolyte in an aluminum battery, in a process for the electrochemical deposition of aluminum and / or in a process for the production of carbon fibers.

14. Use of an aluminum ion-conducting polymer according to any one of claims 10 to 12 as an electrolyte in an aluminum battery, in a process for the electrochemical deposition of aluminum and / or in a process for the production of carbon fibers.

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