Cathode comprising electrically conductive redox polymer and method of making such cathode

Abstract

The invention relates to a method for producing a cathode (1) for a battery cell, comprising: pre-treating a cathode active material (4) with a first covalent binder; reacting the pretreated active material with a monomer in the presence of a solvent, thereby obtaining a cathode mixture; the cathode current collector (2) is pretreated with a second covalent connecting agent; applying a cathode mixture to the pretreated cathode current collector; heating the pretreated cathode current collector to a temperature of 50 DEG C to 150 DEG C to remove the solvent and polymerize the monomers into an electrically conductive redox polymer (5), thereby obtaining a cathode (1); wherein the polymer (5) is covalently linked to the cathode active material (4) and to the cathode current collector (2) via a first covalent linking agent (6) and via a second covalent linking agent (7), respectively. The invention also relates to a cathode (1) comprising the coated cathode current collector (2), and to a battery cell comprising the cathode (1).

Description

Technical Field

[0001] The present invention relates to a method for preparing a cathode comprising a conductive redox polymer and an active material. The present invention also relates to such a cathode, for example a cathode obtained by the above method, and to a battery cell comprising said cathode. Background Art

[0002] Commercial cathodes for cells and batteries, especially for secondary batteries, typically contain an active material, a carbon-based material, and one or more binders to hold the active material and the carbon-based material together. The mixture or slurry is applied to a cathode current collector, which is typically an aluminum foil. The active material ensures ionic conductivity, while the carbon-based material serves as an electron transporter.

[0003] One of the difficulties faced by this type of cathode is that the time between preparing the mixture or slurry and applying it to the cathode current collector is critical. Too thick a layer of mixture, i.e., too thick a coating, tends to break. Another difficulty is that the adhesion between the coating (slurry) and the cathode current collector is usually not good, even when a primer such as silanization is used to improve adhesion.

[0004] Another disadvantage is that the cathode material is stable only within a specific potential range (2-3 plateaus). Deep discharge can lead to charge loss due to irreversible reformulation of the active material.

[0005] Therefore, there is a need for improved cathodes. In particular, there is a need for improved coatings for cathode current collectors, especially with respect to the adhesion of the coating to the cathode current collector.

[0006] Recently, redox polymers have received attention as active materials for cathodes. Several redox polymers show good, sometimes excellent, electrical conductivity in their oxidized form. In addition, their oxidation and reduction are reversible, which allows charging and discharging of the battery cell. An advantage of organic redox polymer cathodes over conventional inorganic transition metal-based cathodes is that they are environmentally friendly, since the organic redox systems are biodegradable.

[0007] WO 2018 / 109150 discloses an electrode material for a cathode in the form of a colloidal solution of a molecular complex comprising at least one redox-active organic oligomer and / or polymer up to nanometer scale and at least one nanometer-scale graphite material, such as graphene oxide, wherein the weight ratio between the redox-active oligomer and / or polymer and the graphite material is 0.5:1 to 20:1. The redox-type organic oligomer and / or polymer used as an active material forms a composite with the graphite material. An adhesive known in the art is used. The composite is applied to a nanometer-scale current collector, and several such compositions can be stacked to obtain a cathode.

[0008] A disadvantage of the above-mentioned electrode materials is that the energy density is limited when such redox polymers are used as active materials. In addition, redox polymers in their reduced form generally exhibit a high electrical resistance. As a result, their use as active materials may be questionable, since this increased electrical resistance is disadvantageous in the discharge of the battery cell. Summary of the invention

[0009] It is an object of the present invention to overcome one or more of the above disadvantages. It is an object of the present invention to provide a method for preparing a cathode for a battery cell, wherein the cathode has a sufficiently high energy density. It is another object of the present invention to provide a method for preparing a flexible cathode. It is another object of the present invention to provide a method for preparing a mechanically stable cathode.

[0010] Another object of the present invention is to provide a cathode for a battery cell, wherein the cathode has an excellent energy density. Another object of the present invention is to provide a flexible cathode, which is also mechanically stable. Another object of the present invention is to provide a cathode with an increased lifetime, which allows a battery cell using the cathode to be repeatedly charged and discharged. Another object of the present invention is to provide a battery cell comprising the cathode of the present invention, wherein the battery cell is able to last for more charge / discharge cycles and has an increased lifetime.

[0011] For purposes of this disclosure, cathode active material and active material may be used interchangeably.

[0012] For purposes of this disclosure, cathode current collector and current collector may be used interchangeably.

[0013] According to a first aspect of the present invention, there is disclosed a method of preparing a cathode for a battery cell, as described in the accompanying claims.

[0014] The method includes the step of pretreating a cathode active material with a first covalent linker, thereby obtaining a pretreated active material.

[0015] The method also includes reacting the pretreated active material with a monomer capable of forming a conductive redox polymer.

[0016] Advantageously, the cathode active material is vanadium-based, nickel-based and / or phosphate-based. In other words, the cathode active material may comprise two or more compounds, wherein each compound is vanadium-based, nickel-based or phosphate-based.

[0017] Advantageously, the first covalent linking agent is an organofunctional silane. Advantageously, the first covalent linking agent is an organofunctional silane according to formula I:

[0018]

[0019] in

[0020] R 1 , R 2 and R 3 Independently C 1-6 Alkoxy, C 1-6 Alkoxyalkoxy, C 1-6 Alkyl or halogen, where R 1 , R 2 and R 3 At most two of them are C 1-6 Alkyl, and

[0021] R 4 It is C 2-6 Alkenyl, C 2-6 Alkynyl, acryloyloxy C 1-6 Alkyl, methacryloyloxy C 1-6 alkyl or 3-glycidyloxypropyl.

[0022] Advantageously, R 1 , R 2 and R 3 At least one of them is C 1-6 Alkoxy or C 1-6 In other words, the first covalent linker is advantageously an organofunctional alkoxysilane. 1 , R 2 and R 3 One, two or all three are C 1-6 Alkoxy or C 1-6 In the case of alkoxyalkoxy, the first covalent linking agent is an organofunctional mono-, di- or tri-alkoxysilane, respectively.

[0023] Advantageously, the first covalent linker is capable of forming a covalent bond between the cathode active material and the monomer. Advantageously, the covalent bond via the first covalent linker is a -Si-O- bond.

[0024] Advantageously, the first covalent linker is connected via R 4 Combined with the monomer and through R 1 , R2 and R 3 One or more of are combined with the cathode active material.

[0025] Advantageously, the monomer is 3,4-ethylenedioxythiophene (EDOT), pyrrole, aniline or acetylene.

[0026] When the pretreated active material reacts with the monomer, a cathode mixture is obtained. The cathode mixture comprises the monomer covalently linked to the cathode active material via a first covalent linker.

[0027] Advantageously, the pretreated active material reacts with the monomer in the presence of a solvent. In other words, the cathode mixture advantageously comprises a solvent. Advantageously, the solvent comprises water and / or an alcohol, or consists essentially of water and / or an alcohol. Non-limiting examples of alcohols include methanol, ethanol, and isopropanol.

[0028] The method further includes pre-treating the cathode current collector with a second covalent linker, thereby obtaining a pre-treated cathode current collector.

[0029] The cathode current collector can be any cathode current collector known in the art, for example, the cathode current collector can comprise, or consist essentially of, aluminum.

[0030] Advantageously, the second covalent linking agent is an organofunctional silane. Advantageously, the second covalent linking agent is an organofunctional silane according to formula I. The first covalent linking agent and the second covalent linking agent may be the same, or may be different.

[0031] Advantageously, the second covalent linker is capable of forming a covalent bond between the current collector and the monomer. Advantageously, the covalent bond via the second covalent linker is a -Si-O- bond.

[0032] Advantageously, the second covalent linker is connected via R 4 Combined with the monomer and through R 1 , R 2 and R 3 One or more of them are combined with a current collector.

[0033] The cathode mixture is then applied to at least a portion of the surface of the pretreated cathode current collector. In other words, at least a portion of the surface of the pretreated cathode current collector is coated with the cathode mixture. The cathode mixture can be applied by methods known in the art.

[0034] The pretreated cathode current collector containing the cathode mixture is then heated to polymerize the monomers into a conductive redox polymer, thereby obtaining a cathode.

[0035] The conductive redox polymer is covalently linked to the cathode active material via a first covalent linker and covalently linked to the cathode current collector via a second covalent linker.

[0036] When the cathode mixture comprises a solvent, the solvent is advantageously removed during heating of the pretreated cathode current collector comprising the cathode mixture.

[0037] Advantageously, the heating step is carried out at a temperature of 30° C. to 200° C., preferably 50° C. to 150° C., more preferably 60° C. to 100° C. In other words, the pretreated cathode current collector comprising the cathode mixture is heated to a temperature of 30° C. to 200° C., preferably 50° C. to 150° C., more preferably 60° C. to 100° C.

[0038] Advantageously, the conductive redox polymer comprises one or more of polythiophene, polypyrrole, polyaniline or polyacetylene.

[0039] Examples of preferred conductive redox polymers include, but are not limited to, poly(3,4-ethylenedioxythiophene) (PEDOT), PEDOT:polystyrene sulfonate, or trimer EPE, where E is 3,4-ethylenedioxythiophene (EDOT) and P is 3,4-propylenedioxythiophene (ProDOT).

[0040] According to a second aspect of the present invention there is disclosed a cathode for a battery cell as described in the accompanying claims.

[0041] Advantageously, the cathode is obtained by the method according to the first aspect of the invention.

[0042] The cathode comprises a cathode current collector, wherein a coating is present on at least a portion of the surface of the cathode current collector, and the coating comprises a conductive redox polymer and a cathode active material.

[0043] The conductive redox polymer is covalently attached to the cathode active material. The covalent bond is obtained via a first covalent linker. In other words, the first covalent linker is covalently attached to the conductive redox polymer and the cathode active material. Advantageously, the first covalent linker compound is an organofunctional silane. Advantageously, the covalent bond via the first covalent linker is a -Si-O- bond.

[0044] The conductive redox polymer is covalently attached to the cathode current collector. The covalent bond is obtained via a second covalent linker. In other words, the second covalent linker is covalently attached to the conductive redox polymer and the cathode current collector. Advantageously, the second covalent linker compound is an organofunctional silane. Advantageously, the covalent bond via the second covalent linker is a -Si-O- bond.

[0045] Advantageously, the conductive redox polymer is as described above.

[0046] Advantageously, the cathode active material is as described above.

[0047] According to a third aspect of the present invention, there is disclosed a battery cell as described in the accompanying claims.

[0048] Advantageously, the battery cell comprises a cathode obtained by the method according to the first aspect of the invention or a cathode according to the second aspect of the invention.

[0049] Advantageously, the battery cell is a secondary battery cell.

[0050] Advantageously, the battery cell further comprises an electrolyte and an anode. The electrolyte may be any electrolyte known in the art. The electrolyte may be a liquid electrolyte or a solid electrolyte. The anode may be any anode known in the art. In other words, one advantage of the cathode of the present invention is that it can be used with any electrolyte and any anode known in the art, i.e., its application in battery cells is widespread.

[0051] Advantageously, the battery cells are lithium-ion battery cells or lithium metal battery cells.

[0052] The method and cathode of the invention have the advantage that the cathode has a less complex composition, i.e. fewer compounds are required. In particular, no binder and no conductive carbon-based compound are required.

[0053] Another advantage of the cathodes of the present invention is that they are mechanically stable, making them robust and resistant to harsh conditions of use and handling.

[0054] Another advantage is that the cathode of the present invention is flexible and tough, which makes the cathode of the present invention applicable to flexible batteries, but is not limited thereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Various aspects of the present invention will now be described in more detail with reference to the accompanying drawings, in which like reference numerals represent like features, and in which:

[0056] - Figure 1 The cathode of the present invention is schematically shown;

[0057] - Figure 2 The cell potential is shown as a function of the charge mass per gram of active material during charge and discharge of the cell for a cell containing a cathode made by the method of the present invention. DETAILED DESCRIPTION

[0058] Advantageously, the first covalent linking agent and the second covalent linking agent are independently of each other an organofunctional silane according to formula I:

[0059]

[0060] in

[0061] R 1 , R 2 and R 3 Independently C 1-6 Alkoxy, C 1-6 Alkoxyalkoxy, C 1-6 Alkyl or halogen, where R 1 , R 2 and R 3 At most two of them are C 1-6 Alkyl, and

[0062] R 4 It is C 2-6 Alkenyl, C 2-6 Alkynyl, acryloyloxy C 1-6 Alkyl, methacryloyloxy C 1-6 alkyl or 3-glycidyloxypropyl.

[0063] When R 1 , R 2 and R 3 One or more of them is C 1-6 alkoxy, they are preferably and independently of each other C 1-3 Alkoxy, more preferably C 1-2 Alkoxy, i.e., methoxy (-OCH3) or ethoxy (-OC2H5).

[0064] When R 1 , R 2 and R 3 One or at most two of them are C 1-6 alkyl, they are preferably and independently C 1-3 Alkyl, more preferably C 1-2 Alkyl, i.e., methyl (-CH3) or ethyl (-C2H5).

[0065] When R 1 , R 2 and R 3 One or more of them is C 1-6 When alkoxyalkoxy groups are present, they are preferably and independently of one another 2-methoxyethoxy (-OCH2CH2OCH3) or methoxyethoxy (-OCH2OCH2CH3).

[0066] When R 1 , R 2 and R 3When one or more of are halogen, they are preferably and independently of each other fluorine (F), chlorine (Cl), bromine (Br) or iodine (I), more preferably Cl.

[0067] When R 4 It is C 2-6 When alkenyl, R 4 C is preferred 2-4 Alkenyl, more preferably C 2-3 Alkenyl, i.e. vinyl (-CH=CH2) or allyl (-CH2CH=CH2). 4 It is C 2-6 When the alkynyl group is 4 C is preferred 2-4 Alkynyl, more preferably C 2-3 Alkynyl, i.e. -C≡CH or -CH2C≡CH.

[0068] When R 4 It is acryloyloxy C 1-6 When alkyl, R 4 Preferably, it is acryloyloxy 1-4 Alkyl, more preferably acryloyloxy 2-3 Alkyl, i.e. acryloyloxyethyl or acryloyloxypropyl. 4 It is methacryloyloxy C 1-6 When alkyl, R 4 Preferably, it is methacryloyloxy 1-4 Alkyl, more preferably methacryloyloxy 2-3 Alkyl, i.e., methacryloxyethyl or methacryloxypropyl.

[0069] Examples of preferred organofunctional silanes are listed in Table 1.

[0070] Table 1: Examples of Preferred Organofunctional Silanes

[0071]

[0072] Advantageously, the conductive redox polymer comprises redox active groups. Non-limiting examples of redox active groups include quinone, catechol and hydroquinone.

[0073] Figure 1 The cathode 1 obtained by the method of the present invention is schematically shown. The cathode 1 comprises a current collector 2 and a coating 3 present on the surface of the current collector.

[0074] The coating 3 contains an active material 4 which is advantageously vanadium-based, nickel-based and / or phosphate-based.

[0075] Non-limiting examples of vanadium-based active materials include V2O5, V2O3, VO, H3V5O7, H2V3O8. Optionally, the vanadium-based active material may contain lithium. Non-limiting examples of lithium-containing vanadium-based active materials include Li x V3O8, where x is between 1 and 4; Li y H 0.5 V3O8, where y is between 0.5 and 4.5; and Li z V2O5, wherein z is between 0.1 and 4. For example, the active material may comprise a mixture of two or more vanadium-based compounds, such as V2O5, V2O3, VO, H3V5O7, and H2V3O8.

[0076] Non-limiting examples of nickel-based active materials include lithium nickel cobalt manganese oxide (LiNiCoMnO2, or NMC), lithium nickel manganese spinel (LiNi 0.5 Mn 1.5 O4, or LNMO) and lithium nickel cobalt aluminum oxide (LiNiCoAlO2, or NCA).

[0077] An example of a phosphate-based active material is lithium iron phosphate (LiFePO 4 , or LFP), but is not limited thereto.

[0078] The coating 3 further comprises a conductive redox polymer 5. Advantageously, the conductive redox polymer comprises one or more of polythiophene, polypyrrole, polyaniline or polyacetylene.

[0079] The active material 4 is covalently linked to the conductive redox polymer 5 via a first covalent bond 6. The first covalent bond 6 is achieved or obtained via a first covalent linker. The first covalent linker is advantageously as described above, for example, a compound as shown in Table 1. In other words, the first covalent linker is covalently linked to the active material 4 and the redox polymer 5 at the same time.

[0080] Different molecules of the active material 4 can be interconnected via the first covalent bonds 6 and the redox polymer 5, thereby forming a three-dimensional network, which allows the coating 3 to be structured, ie to obtain a coating 3 with a specific thickness.

[0081] The active material 4 is also connected to the current collector 2. This bonding is achieved via the redox polymer 5, which is covalently connected to the active material 4 via the first covalent bond 6 as described above. The redox polymer 5 is also covalently connected to the current collector 2 via a second covalent bond 7. The second covalent bond 7 is achieved or obtained via a second covalent linker. The second covalent linker is advantageously as described above, for example, a compound as shown in Table 1. In other words, the second covalent linker is covalently connected to the cathode current collector 2 and the redox polymer 5 at the same time.

[0082] It is generally known that the strength of covalent bonds is several orders of magnitude higher than other types of bonds, such as hydrogen bonds. Advantageously, covalent bonds are also significantly more stable. Therefore, the covalent bonds 6, 7 provide a strong and stable connection between the active material 4 and the cathode current collector 2.

[0083] The inventors have found that such a strong and stable connection allows obtaining or preparing mechanically stable cathodes. The inventors have found that said cathodes are flexible and ductile and that they can resist any mechanical manipulation or pressure applied to the cathode without mechanical damage, such as cracks or breaks.

[0084] In addition, the covalent bond between the active material 4 and the current collector 2 and the resulting mechanical stability allow thicker coatings to be deposited. An advantage of thicker coatings is that higher energy densities can be achieved. Another advantage of thicker coatings is that the space in the battery cell can be optimized.

[0085] Advantageously, the coating 2 has a thickness of 10 to 200 μm, for example 20 to 175 μm, 40 to 150 μm, preferably 60 to 125 μm, more preferably 80 to 100 μm.

[0086] Advantageously, the redox polymer can undergo repeated oxidation and reduction, i.e., the redox polymer undergoes reversible oxidation and reversible reduction. Therefore, a battery cell comprising a cathode containing a redox polymer according to the invention can be repeatedly charged (oxidation of the redox polymer) and discharged (reduction of the polymer).

[0087] Advantageously, when the redox polymer is reduced, its electrical resistance increases and it thus becomes more electrically insulating. This allows the active material to be protected via electrical insulation, so-called micro-local protection.

[0088] Advantageously, the discharge potential of the conductive redox polymer is higher than the redox potential of the active material, but lower than the available redox potential window of the active material. This discharge potential prevents the battery cell from entering a deep discharge state. It is known that when a battery cell enters a deep discharge state, the cathode undergoes irreversible structural changes. This structural change leads to inherent safety issues for the battery cell, as oxygen can be released from the cathode material and can react violently with the liquid electrolyte, leading to fire.

[0089] Therefore, a cell of the invention comprising the cathode 1 of the invention is inherently safer than a conventional cell having the same electrolyte and anode, but comprising a commercially available cathode.

[0090] Example

[0091] Example 1: Preparation of the cathode of the present invention

[0092] A 1 volume % solution of gamma-methacryloxypropyltrimethoxysilane (CAS 2530-85-0) in water was prepared at a pH of 3.5 to 4.5 (first solution).

[0093] The first solution was coated on an aluminum substrate as a cathode current collector in an amount of 10 μL / cm 2 , followed by drying at a temperature of 110° C. to 120° C. for 2 hours, thereby obtaining pretreated aluminum (ie, a pretreated cathode current collector).

[0094] A second solution was prepared by adding 10 g of V2O5 as an active material to 10 mL of water. Mixing was performed to obtain a uniform second solution. Then, 1.5 mL of the first solution was added to the second solution. The resulting mixture was then dried at a temperature of 110° C. to 120° C. for 2 hours, thereby obtaining pretreated V2O5 (i.e., pretreated active material). Then, 10 g of the pretreated active material was added to 10 mL of water to form a third solution.

[0095] A fourth solution was prepared by adding 0.1 g of EDOT (2,3-dihydrothiophene[3,4-b]-1,4-dioxin) as a monomer, 0.1 g of lithium p-toluenesulfonate, and 1 g of polyethylene glycol to 10 mL of water.

[0096] Then, the fourth solution was added to the third solution, thereby obtaining a fifth solution, and mixed to obtain a uniform mixture. Then, the uniformly mixed fifth solution was coated on the pretreated aluminum, followed by drying at a temperature of 80° C. to 100° C. for 2 hours. During this drying step, the EDOT monomer was polymerized into a PEDOT polymer.

[0097] Example 2: Battery Cell Containing a Cathode of the Invention

[0098] A battery cell was prepared comprising the cathode described in Example 1. As anode, lithium foil on lithium foil was used. The electrolyte was a liquid electrolyte of 2M lithium bis(fluorosulfonyl)amide (LiFSI) in dimethyl ether (DME).

[0099] The cell was charged and discharged at 0.2 mA / cm2, and the cell potential (voltage) was measured at room temperature as a function of the charge-to-mass ratio per gram of active material V2O5. Figure 2 The results obtained for charging (10) and discharging (11) are shown and are as expected and show very good cell performance and hence excellent performance of the cathode of the present invention.

[0100] Reference Mark:

[0101] 1. Cathode;

[0102] 2. Cathode current collector;

[0103] 3. Coating;

[0104] 4. Cathode active material;

[0105] 5. Conductive redox polymers;

[0106] 6. a covalent bond via a first covalent linker; 7. a covalent bond via a second covalent linker;

[0107] 10.Charging mode;

[0108] 11.Discharge mode.

Claims

1. A method for preparing a cathode (1) for a battery cell, the method comprising the following steps: - pre-treating the cathode active material (4) with a first covalent linker, thereby obtaining a pre-treated active material, - reacting the pretreated active material with a monomer capable of forming a conductive redox polymer (5) in the presence of a solvent, thereby obtaining a cathode mixture comprising the monomer covalently linked to the cathode active material via a first covalent linker (6), - pre-treating the cathode current collector (2) with a second covalent linker, thereby obtaining a pre-treated cathode current collector, - applying the cathode mixture to at least a portion of the surface of a pretreated cathode current collector, - heating the pretreated cathode current collector comprising the cathode mixture to a temperature of 50° C. to 150° C., thereby removing the solvent, polymerizing the monomers into the conductive redox polymer (5), and obtaining the cathode (1), The method is characterized in that the conductive redox polymer (5) is covalently linked to the cathode active material (4) via a first covalent linker (6) and covalently linked to the cathode current collector (2) via a second covalent linker (7).

2. The method according to claim 1, wherein the cathode active material (4) is vanadium-based, nickel-based and / or phosphate-based.

3. The method according to any one of the preceding claims, wherein the solvent comprises water and / or an alcohol.

4. The method according to any one of the preceding claims, wherein the heating is carried out at a temperature of 60 to 100°C.

5. The method according to any one of the preceding claims, wherein the conductive redox polymer (5) comprises one or more of polythiophene, polypyrrole, polyaniline or polyacetylene.

6. The method according to any of the preceding claims, wherein the conductive redox polymer (5) is poly(3,4-ethylenedioxythiophene) (PEDOT), PEDOT:polystyrene sulfonate, or a trimer EPE, wherein E is 3,4-ethylenedioxythiophene (EDOT) and P is 3,4-propylenedioxythiophene (ProDOT).

7. The method according to any one of the preceding claims, wherein the first covalent linker and / or the second covalent linker is an organofunctional silane, and wherein the covalent bond via the first covalent linker (6) and / or the covalent bond via the second covalent linker (7) is a -Si-O- bond.

8. The method of claim 7, wherein the organofunctional silane is an organofunctional alkoxysilane.

9. A cathode (1) for a battery cell, comprising a cathode current collector (2), wherein a coating (3) is present on at least a portion of the surface of the cathode current collector (2), wherein the coating (3) comprises a conductive redox polymer (5) and a cathode active material (4), characterized in that The conductive redox polymer (5) is covalently linked to the cathode active material (4) via a first covalent linker (6) and covalently linked to the cathode current collector (2) via a second covalent linker (7).

10. The cathode according to claim 9, wherein the first covalent linker compound and / or the second covalent linker compound is an organofunctional silane, and wherein the covalent bond via the first covalent linker (6) and / or the covalent bond via the second covalent linker (7) is a -Si-O- covalent bond.

11. The cathode according to claim 9 or 10, wherein the conductive redox polymer (5) comprises one or more of polythiophene, polypyrrole, polyaniline or polyacetylene.

12. The cathode according to any one of claims 9-11, wherein the conductive redox polymer (5) is poly(3,4-ethylenedioxythiophene) (PEDOT), PEDOT:polystyrene sulfonate, or a trimer EPE, wherein E is 3,4-ethylenedioxythiophene (EDOT) and P is 3,4-propylenedioxythiophene (ProDOT).

13. The cathode according to any one of claims 9 to 12, wherein the cathode active material (4) is vanadium-based, nickel-based and / or phosphate-based.

14. A battery cell comprising a cathode (1) obtained by the method according to any one of claims 1 to 8, or comprising a cathode (1) according to any one of claims 9 to 13. The battery cell according to claim 14 , wherein the battery cell is a secondary battery cell.

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