Method for producing an electrode for an electrochemical energy storage device and electrochemical energy storage device

Abstract

Method for producing an electrode for an electrochemical energy storage device, comprising the method steps: a) Providing a base body; b) applying an active material matrix to the base body, wherein the active material matrix comprises at least one binder, optionally an active material (1), and a pore former (3), wherein the pore former (3) is soluble in a solvent in which further components of the active material matrix are insoluble or only partially soluble; c) if necessary, drying the active material matrix; d) washing out the pore former (3) by treating the active material matrix with the solvent and e) Introducing an active material into the generated pores of the active material matrix.

Description

[0001] The present invention relates to a method for producing an electrode for an electrochemical energy storage device. The present invention further relates to a method for producing an electrochemical energy storage device. The present invention further relates to an electrode for an electrochemical energy storage device and an electrochemical energy storage device, such as, in particular, a lithium-ion battery. State of the art

[0002] Lithium-based energy storage systems offer great application potential due to their high performance. Secondary batteries based on lithium and sulfur, for example, are promising for use in at least partially electric vehicles due to the high potential specific capacity of sulfur (1672 mAh / g) and lithium (3862 mAh / g).

[0003] For example, document DE 699 06 814 T2 discloses a lithium-sulfur battery and a method for its production. According to this document, the highest possible volumetric density of the electroactive material in the cathode active layer is to be achieved. To this end, in one production step, the electroactive sulfur-containing material is heated to a temperature above its melting point, and then the molten electroactive sulfur-containing material is resolidified to obtain a cathode active layer with a high volumetric density.

[0004] From the document JP 2009-146 581 A, a foil-shaped negative electrode for the lithium-ion secondary battery is known, which contains carbon-containing particles that store and release lithium ions, and a binder for binding the carbon-containing particles as well as a pore volume per pore mass with diameters in the range of 0.05 to 100 µm 0.07 to 1.0 cm 3 / g. The sheet-shaped negative electrode for the lithium-ion secondary battery may contain a fibrous carbonaceous material, and a thermosetting resin may be used as a binder.

[0005] From the document DE 21 63 185 A a method is known for producing electrode structures for chemoelectric cells by joining, preferably by means of a sintering process, particles of electrode material in the presence of particles of a pore-forming material, which is removed from the electrode structure after the particles of the electrode material have formed a coherent porous body.

[0006] From the document WO 00 / 25 376 A1 a method for producing electrodes (8) for electrochemical storage devices is known which have charge storage material particles which are uniformly distributed over the entire electrode in order to facilitate the formation of a uniform network of interconnected pores. Disclosure of the invention

[0007] The present invention relates to a method for producing an electrode for an electrochemical energy storage device, in particular for a lithium-ion battery, comprising the method steps: a) Providing a base body; b) applying an active material matrix to the base body, wherein the active material matrix comprises at least one binder, optionally an active material, and a pore former, wherein the pore former is soluble in a solvent in which further components of the active material matrix are insoluble or only partially soluble; c) if necessary, drying the active material matrix; d) washing out the pore former by treating the active material matrix with the solvent; and e) Introducing an active material into the generated pores of the active material matrix.

[0008] In the context of the present invention, a lithium-ion battery can be understood in particular as a battery that is at least partially based on lithium and uses lithium or lithium ions in the electrochemical process of its charging or discharging cycle. For example, a lithium-ion battery can be a lithium-sulfur battery or a lithium-air battery. Furthermore, the term "battery" can be understood in particular as a primary cell or a secondary cell, i.e., in particular a rechargeable accumulator.

[0009] A base body, within the meaning of the present invention, can be, in particular, a base substrate, which can serve as the core of the electrode and, as such, can at least partially predetermine the shape, geometry, and / or size of the electrode. For example, a base body can be or comprise a current collector. A current collector can be understood, in particular, as an electrically conductive element, which can, for example, extend from the interior of a cell space, optionally through a housing, into an area outside the cell space, and can thus serve, in particular, to tap electrical energy from the energy storage device.

[0010] An active material matrix can further be understood as meaning, in particular, a layer or a layer in which the material which is electrochemically active during a charging and / or discharging process is arranged at least partially or temporarily.

[0011] By means of a method according to the invention, it may be possible to provide an electrode for an energy storage device which provides improved cycle stability and high stability while simultaneously providing high capacity.

[0012] Such an electrode can offer the particular advantage of being able to produce a defined porosity while reducing the sulfur content, while still achieving comparable capacities. For example, the sulfur content can be reduced to 45% or even lower. The sulfur content can correlate with the available options for Li2S / Li2S2 deposition, which can result in an increase in the specific capacity of the electrode.

[0013] For this purpose, a base body is provided in a first method step a). The base body can be, for example, a current collector or another element, which can be designed, for example, as an integral component of an electrode. For example, the current collector can be designed as a metal foil, for example comprising or consisting of aluminum or copper.

[0014] In process step b), an active material matrix is ​​applied or applied to the base body. This can be achieved, for example, by doctoring a suitable mixture. The mixture intended to form the active material matrix optionally, but not necessarily, comprises at least one active material that can actively participate in the electrochemical processes occurring during a charging and / or discharging process of the energy storage device. For example, a single active material or a suitable mixture of a plurality of different active materials can be used. Purely exemplary and non-limiting examples of one or more active materials include, for example, elemental sulfur or sulfur compounds for the purely exemplary case of a lithium-sulfur battery.The mixture further comprises a binder, which can serve in particular as the actual matrix material for the mixture or for the active material matrix to be applied. For example, the binder can comprise a polymer, such as polyvinylidene fluoride (PVDF), cellulose-based binders or even Teflon, or mixtures thereof. In addition to the active material and the binder, the mixture can further contain one or more solvents, which can impart a consistency suitable for processing to the mixture. For example, an organic solvent can serve as the solvent. N-methyl-2-pyrrolidone (NMP) is mentioned here as an exemplary and non-limiting example. In addition, such a mixture can further comprise a pore former.A pore-forming agent can, in particular, be a substance that is present in the mixture, for example, as a solid, and can be removed from the active material matrix in a later process step. This allows a layer to be produced to comprise a precisely defined number of pores with a precisely defined dimension, whereby both the number and the dimension of the pores to be formed can be adjusted by a suitable choice of the pore-forming agent. In particular, in a process described above, at least partially open porosity is automatically generated.

[0015] The pore-forming agent can, in particular, be soluble in a solvent in order to subsequently remove it from the matrix in a solvent-based process step d), as explained below. The pore-forming agent or the solvent in which the pore-forming agent is soluble is further selected such that other components, in particular all of the other components, of the mixture or of the produced active material matrix are not soluble in this solvent or are only partially soluble in this solvent.Suitable solubilities for the pore former are in a range of greater than or equal to 0.05 mol / l, in particular greater than or equal to 0.5 mol / l, whereas solubilities of, for example, the binder or the active material or further components of the active material matrix are in a range of less than 0.05 mol / l, preferably less than or equal to 0.005 mol / l, in each case at a temperature of 25°C, in order to be insoluble or only partially soluble according to the invention.

[0016] Furthermore, a conductive additive or a plurality of conductive additives can be present in the active material matrix or in the mixture used to form an active material matrix, which can improve a charging or discharging process when the electrode is used, for example, in an electrochemical energy storage device. This can be particularly advantageous if, for example, the active material and / or the binder itself, or possibly intermediate products of the active material, such as lithium sulfide and lithium disulfide in the case of a lithium-sulfur battery, have limited electrical conductivity. Carbon black and / or graphite, for example, can be used as conductive additives.

[0017] After applying the active material matrix or the aforementioned mixture to the base body, the active material matrix or the base body with the active material matrix can be dried, in particular to remove the solvent, such as the organic solvent, which may be present in the mixture. For this purpose, the active material matrix can be subjected to a vacuum application and / or heat exposure. After drying the active material matrix, a base body, such as in particular a current collector, can thus be obtained, on which an active material matrix comprising a binder, optionally active material and optionally a conductive additive is arranged. Furthermore, the active material matrix produced in this way contains the pore former, whereby a precisely defined porosity of the structure of the active material matrix can be adjusted in a further process step d).

[0018] In particular, in process step d), the pore-forming agent can be washed out by treating the active material matrix with a solvent. In other words, it can be exploited that, as described above, a pore-forming agent is used that is soluble in a solvent that does not dissolve, or only partially dissolves, the other components of the active material matrix, such as in particular the binder and the active material and, if appropriate, the conductive additive. Thus, simply by acting on the active material matrix with the solvent, the pore-forming agent can be removed from the matrix, whereby the volumes or cavities formerly filled by the pore-forming agent particles now form precisely defined pores. The pore size can be adjusted by selecting the pore-forming agent particles.For example, the desired size of the pores or cavities can be adjusted by suitable comminution of the pore-forming agents or pore-forming particles, such as by grinding, since subsequent washing out creates cavities with corresponding dimensions and in corresponding numbers instead of the pore-forming particles.

[0019] In particular, by washing out the pore-forming agent(s) as described above, a porous electrode structure can be created in a particularly simple and cost-effective manner. Because the pore-forming agent can be safely and completely removed from the matrix, a particularly precise and defined porosity can be achieved.

[0020] The porous electrode structure thus produced can be dried in a further process step to remove the solvent of the pore former.

[0021] In a further process step, active material is introduced into the pores, for example by melting the active material and then cooling it. The active material can be configured as described above.

[0022] According to the invention, a precisely defined porous electrode structure, such as in particular a cathode structure, can thus be produced in a particularly simple manner. The targeted adjustment of the electrode porosity is essentially independent of the porosity of the other materials used, such as the conductive additive. In lithium-sulfur batteries, for example, the electrode porosity can be adjusted for optimal cycle stability and, at the same time, the amount of sulfur in the cathode can be optimized according to the available conductive surface of the porous matrix, such as a carbon surface. The overall porosity, i.e. in particular the porosity due to the dissolving sulfur and the leaching of the pore-forming agent, which arises in addition to the porosity of the conductive additive, for example a porous carbon black, of the electrode, such as in particular in the cathode, can thus be adjusted independently of the amount of sulfur used.By avoiding excess sulfur, which may not be fully utilized due to surface limitations of the conductive additive used, the specific capacity of lithium-sulfur batteries, for example, can be optimized while maintaining optimal porosity for high cycle stability.

[0023] By producing a particularly defined porous electrode structure according to the invention, it is possible to respond to the fact that the overall reaction Li + S8 ↔ Li2S, for example in a lithium-sulfur battery, comprises several polysulfide intermediates with different sulfur chain lengths, which are readily soluble in common electrolyte systems, such as 1,3-dioxolane (DOL) / dimethoxyethane (DME) with lithium bis(trifluoromethylsulfonylimide) (LiTFSI) as the conductive salt. The reaction products lithium disulfide (Li2S2) and lithium sulfide (Li2S), on the other hand, are almost insoluble, for example, in the solvents or electrolyte systems mentioned above, and can therefore precipitate in the cathodic matrix.

[0024] Since lithium sulfide, for example, has a volume approximately 1.8 times higher than elemental sulfur, a discharge or charging process of, for example, a lithium-sulfur battery is associated with a significant volume change in the cathodic structure. This can fundamentally lead to mechanical stresses, which can lead to degradation of the electrode morphology and thus impair the cycle stability of such a battery. Because the process according to the invention can maintain a suitable porosity and thus additional volume in addition to the existing active material, such as sulfur, an electrode produced according to the invention has a structure that can remain particularly stable over a large number of charge or discharge cycles despite the aforementioned volume changes.

[0025] For example, if sulfur is present in particles with a typical diameter of approximately 30 µm, cavities of the same size can form at the original locations of the sulfur particles after the first discharge, during which all of the sulfur is reduced and can dissolve in the form of polysulfides. These cavities, or pores, help the cathodic structure achieve a high porosity, which can be advantageous for ensuring uniform penetration of the cathodic material, for example, with polysulfide-containing electrolyte.

[0026] Because, in addition to the previously described formation of cavities by dissolving the sulfur during a cell discharge process, further defined pores or cavities are present in an electrode structure produced according to the invention, the available electrically conductive surface, which is necessary for the necessary electrical contacting of the electronically non-conductive sulfur or the electronically non-conductive sulfur species as the active material, for example, can be increased in cathodes with a high sulfur content. The resulting Li2S or Li2S2 can precipitate in the electrode structure or cathode structure and cover the electrically conductive surface available for reduction, whereby essentially all polysulfides dissolved in the electrolyte can be reduced by the large coverable surface.This can prevent, or at least significantly reduce, the retention of unused active material in the electrode or in an energy storage device equipped with an electrode produced according to the invention, thereby increasing the specific capacity according to the invention. The stability of the pore structure produced according to the invention also allows for further improvement of the cycling stability.

[0027] The inventive method for producing an electrode, or in particular a cathode, for a lithium-sulfur battery allows the amount of sulfur to be reduced during production or adjusted to the available conductive surface, for example, a carbon surface, in the cathode. The porosity of an electrode produced in this way can be adjusted to the level of a cathode with a higher sulfur content or to any other desired level of cathode with high cycling stability, without excess unused sulfur species remaining in the cell.

[0028] In lithium-air batteries, for example, the targeted adjustment of electrode porosity or cathode porosity can also be advantageous, since, analogous to lithium-sulfur batteries, a solid, such as lithium oxide, precipitates during discharge, which can lead to high mechanical stress in the cathodic structure and impaired cycle stability. Thus, a manufacturing process for electrodes according to the invention also improves the stability or cycle stability of lithium-air batteries.

[0029] Although cathodes as electrodes are discussed above and below, it is clear to the person skilled in the art that an anode can equally be understood by the term electrode in the sense of the present invention.

[0030] In one embodiment, the pore-forming agent can comprise a salt. Such a pore-forming agent can thus be soluble, in particular, in a polar solvent. In this embodiment, a variety of readily available salts can be used as pore-forming agents, which can make the production process according to the invention particularly simple and cost-effective. Furthermore, suitable mixtures for producing an active material matrix usually comprise constituents or components that are not soluble in polar solvents, such as water or alcohols, in particular short-chain alcohols, but would rather require non-polar or organic solvents. For example, polymers that are insoluble in polar solvents are usually used as binders.Furthermore, frequently used conductive additives, such as graphite, carbon black, or other carbon compounds, or even the active material itself, are insoluble in polar solvents. Furthermore, polar solvents, especially water, are readily available and can be used without posing an environmental threat, so that a process according to the invention can also be particularly environmentally friendly.

[0031] In a further embodiment, the pore-forming agent can comprise sodium chloride, potassium chloride, or barium acetate. Such pore-forming agents, in particular, can be easily removed from the formed electrode structure using polar solvents such as water, thus easily creating defined pores. Furthermore, by processing or specifically producing such crystals or pore-forming particles, the size of the particles or salt crystals used, and thus the size of the pores to be created, can be adjusted particularly precisely and easily.

[0032] Within the scope of a further embodiment, the pore former can comprise particles which have a size in a range from greater than or equal to 0.01 µm to less than or equal to 50 µm, in particular greater than or equal to 0.1 µm to less than or equal to 30 µm. In this embodiment, an electrode structure can be created which has pore sizes in which the active material can be deposited particularly advantageously during a charging process of an energy storage device equipped with an electrode produced according to the invention or can dissolve again during a discharging process, so that a particularly high specific capacity can be achieved. Furthermore, in this embodiment, particularly stable electrode structures can be produced which can easily withstand the conditions prevailing during the operation of lithium-ion batteries, for example.

[0033] In a further embodiment, the pore former can be present in the active material matrix in a concentration ranging from greater than 0 wt.% to less than or equal to 30 wt.%. In this embodiment, in particular, the number of pores to be created and thus the pore penetration of the electrode structure can be adjusted particularly advantageously. In particular, in this embodiment, an electrode structure can be created which has sufficient stability, but can form sufficient cavities so that the active material can be deposited on the electrically conductive surface during a charging process, whereby the loss of active material can be prevented or reduced to a minimum. The aforementioned values ​​refer to the finished and dry electrode or active material matrix before the pore former is washed out.

[0034] In a further embodiment, an active material matrix can be applied to the base body, which comprises: greater than or equal to 5 wt% to less than or equal to 80 wt% sulfur, greater than or equal to 5 wt% to less than or equal to 90 wt% SPAN, greater than or equal to 2.5 wt.% to less than or equal to 90 wt.% conductive additive, greater than or equal to 2.5 wt% to less than or equal to 50 wt% binder, greater than 0 wt.% to less than or equal to 30 wt.% pore former, and greater than or equal to 30 wt% to less than or equal to 95 wt% solvent.

[0035] In this embodiment, sulfur can be understood in particular as elemental sulfur, which can be present in particular in particles with a size of, for example, greater than or equal to 20 µm down to a size of less than or equal to 40 µm. In this embodiment, SPAN can be understood in particular as a sulfur-polyacrylonitrile composite. This can be obtained, for example, by a reaction in which polyacrylonitrile (PAN) is heated with an excess of elemental sulfur, whereby the sulfur is cyclized with polyacrylonitrile to form H2S and then bound in the cyclized matrix. In this embodiment, the conductive additive can be, in particular, graphite or carbon black. For example, only one conductive additive or a mixture of suitable conductive additives can be provided which together lie within the prescribed concentration range.A binder can be understood, in particular, as a matrix, which, for example, as described above, can be made of a suitable polymer, such as polyvinylidene fluoride (PVDS). The pore-forming agent serves, in particular, to form pores or cavities and, as described above, is washed out in a later step. For example, a water-soluble salt, in particular sodium chloride, potassium chloride, or barium acetate, can be used as the pore-forming agent. The solvent can, in particular, comprise or be N-methyl-2-pyrrolidone.

[0036] Surprisingly, it was found that, particularly in a prescribed embodiment, a particularly cycle-stable electrode structure could be produced which can have pores in a suitable number and size.

[0037] Within the scope of a further embodiment, an electrode can be produced with a thickness ranging from greater than or equal to 20 µm to less than or equal to 200 µm. Such electrodes could, in particular, be suitable for accommodating pores of a suitable size, enabling particularly stable cycling behavior. Furthermore, such electrodes can be easily used in a wide variety of configurations, particularly in lithium-ion batteries.

[0038] With regard to further advantages and technical features of this method according to the invention, reference is hereby explicitly made to the explanations in connection with the further method according to the invention, the electrode according to the invention, the energy storage device according to the invention, the figures, and the description of the figures.

[0039] The present invention further relates to a method for producing an electrochemical energy store, in particular a lithium-ion battery, comprising a method for producing an electrode as described above. A method for producing an electrode as configured above can be used particularly advantageously in a manufacturing process for an electrochemical energy store, such as in particular a lithium-ion battery. In particular with such energy stores, it can be advantageous that an electrode can be produced, or can be used in this electrochemical energy store, which has a high and defined porosity in order to thus make substantially all of the active material available for a charging and / or discharging process.In addition, an electrode produced in this way can particularly advantageously withstand volume changes of the active material, such as can occur during a charging and / or discharging process of an electrochemical energy storage device.

[0040] With regard to further advantages and technical features of this method according to the invention, reference is hereby explicitly made to the explanations in connection with the further method according to the invention, the electrode according to the invention, the energy storage device according to the invention, the figures, and the description of the figures.

[0041] The present invention further relates to an electrode comprising a base body, such as in particular a current collector, and an active material matrix arranged on the base body, wherein the active material matrix comprises a binder, an active material, and optionally a conductive additive, wherein a defined porosity is provided in the active material matrix, the pores of which are at least partially shaped like a crystal. Such an electrode, which in particular comprises such a porous electrode structure, can in particular have improved cycling behavior or in particular improved cycling stability. This can be achieved by providing a porosity that exceeds the natural porosity that forms through dissolution processes of the active material.This makes it particularly advantageous to ensure that sufficient electrically conductive surface is available for the entire active material during a charging process, so that all of the active material can be reduced and made available again for a subsequent discharging process. This prevents the active material from failing and becoming unavailable for a further charging or discharging process. An electrode according to the invention can therefore have a particularly high capacity that remains stable even over many charging or discharging cycles. Such an electrode can be particularly easy to produce, in particular by a method described above using a salt as a pore former. In detail, the pores can be formed by the presence of a salt or a salt crystal.The crystallites of the pore-forming agent used have a typical shape according to the corresponding crystal structure, such as a cubic shape in sodium chloride. When these crystallites are dissolved from the matrix, the cavities then at least partially possess the corresponding shape. At least partially the corresponding shape can mean, in particular, that, due to the formation of open pores, the pores or cavities do not completely or entirely reflect the corresponding crystal shape, but may be open.

[0042] With regard to further advantages and technical features of the electrode according to the invention, reference is hereby explicitly made to the explanations in connection with the methods according to the invention, the energy storage device according to the invention, the figures, and the description of the figures.

[0043] The present invention further relates to an electrochemical energy storage device, in particular a lithium-ion battery, comprising an anode, a cathode, and an electrolyte arranged between the anode and the cathode. The energy storage device has at least one electrode, in particular a cathode, configured as described above. Furthermore, such an energy storage device includes a separator, as will be understood by those skilled in the art. Such an energy storage device is particularly stable over the long term and, due to its high capacity, offers high cycle stability even over many charging and discharging cycles.

[0044] With regard to further advantages and technical features of the energy storage device according to the invention, reference is hereby explicitly made to the explanations in connection with the electrode according to the invention, the methods according to the invention, the figures, and the description of the figures. Drawings and examples

[0045] Further advantages and advantageous embodiments of the inventive objects are illustrated by the drawings and explained in the following description. It should be noted that the drawings are for descriptive purposes only and are not intended to limit the invention in any way. They show: Fig. 1 a schematic representation of an electrode precursor during a process step for producing the electrode; and Fig. 2 a schematic representation of a finished electrode before a first discharge process.

[0046] In Fig. Figure 1 shows a schematic representation of an electrode precursor during a process step for producing the electrode for an electrochemical energy storage device. Such an electrode or energy storage device can be used, for example, as energy sources in portable devices such as portable computers, mobile phones, and other consumer applications.

[0047] Other areas of application include power tools, garden tools, and electrically powered vehicles, such as hybrid or plug-in hybrid vehicles or fully electric vehicles. Overall, such an electrode or electrochemical energy storage device can be used in applications where high specific energy may be essential.

[0048] In the process step according to Fig. 1 shows in particular an active material matrix which is formed on a base body which is Fig. 1 is not shown, can be applied, for example by doctor blade coating. The active material matrix can comprise a matrix 2, which can comprise a binder and, for example, a conductive additive. Particles of an active material 1 are also arranged in the matrix 2. Furthermore, Fig. 1, that a pore former 3 or particles of a pore former 3 are arranged in the matrix 2. The pore former 3 is soluble in a solvent in which other components of the active material matrix are insoluble or only partially soluble.

[0049] In particular, the pore-forming agent 3 can comprise a salt that is soluble in a polar solvent, such as water or an alcohol. For example, the pore-forming agent 3 can comprise sodium chloride, potassium chloride, or barium acetate, or consist of these components. Furthermore, in order to create a particularly advantageous pore size, the pore-forming agent 3 can comprise particles, such as salt crystals, that have a size in a range from greater than or equal to 0.01 µm to less than or equal to 50 µm, in particular greater than or equal to 0.1 µm to less than or equal to 30 µm.

[0050] Alternatively or additionally, the pore-forming agent 3 can also be present in the active material matrix at a concentration ranging from greater than 0 wt.% to less than or equal to 30 wt.% in order to achieve particularly advantageous pore penetration. As a specific embodiment, an active material matrix can be applied to the base body, comprising: greater than or equal to 5 wt% to less than or equal to 80 wt% sulfur, greater than or equal to 5 wt% to less than or equal to 90 wt% SPAN, greater than or equal to 2.5 wt.% to less than or equal to 90 wt.% conductive additive, greater than or equal to 2.5 wt% to less than or equal to 50 wt% binder, greater than 0 wt.% to less than or equal to 30 wt.% pore former and greater than or equal to 30 wt% to less than or equal to 95 wt% solvent.

[0051] In one embodiment, a possible manufacturing process comprises the following steps. First, the active material 1 or a mixture of active materials 1, in particular sulfur and SPAN, is stirred or ground together with a solvent, such as NMP, in a speed mixer or ball mill for approximately 30 minutes. Subsequently, the conductive additive, such as carbon black, and the pore-forming agent 3, such as a water-soluble salt, are added. After a further 10 minutes of stirring or grinding, graphite can be added as an additional conductive additive and a binder solution. The resulting mixture can be stirred for a further 5 minutes. The resulting slurry or mixture can be applied to a current collector, such as aluminum foil, using a doctor blade. The resulting electrode precursor can then be dried on a hotplate at 60°C for 2 hours.The electrode precursor can then be transferred to a vacuum oven and dried there for a further 12 hours at 60 °C. The pore-forming agent or salt can then be dissolved out with distilled water or a suitable polar solvent, and the electrode can be dried again. A suitable thickness of the produced electrode can be in the range between 20 µm and 200 µm and can be adjusted, for example, using a doctor blade process. An exemplary mixture for forming an active material matrix can comprise 60% sulfur, 10% carbon black, 10% graphite, and 20% PVDF, with the thickness of the dry electrode being approximately 90 µm.

[0052] This creates an active material matrix that Fig. 2. This further comprises a matrix 2 in which particles of the active material 1 are arranged. Furthermore, pores 4 are present at the locations where the pore-forming agent 3 was located.

[0053] Fig. Figure 2 thus shows a cross-section of an electrode in a finished state immediately after the manufacturing process and before the first discharge process. After a discharge process, the active material 1 can dissolve in an electrolyte system and, during a subsequent charging process, can settle or accumulate both in the cavities of the active material 1 and in the pores 4. This means that the entire active material 1 is available for a discharge process again after a charging process.

Claims

[1] Method for producing an electrode for an electrochemical energy storage device, comprising the method steps: a) Providing a base body; b) applying an active material matrix to the base body, wherein the active material matrix comprises at least one binder, optionally an active material (1), and a pore former (3), wherein the pore former (3) is soluble in a solvent in which further components of the active material matrix are insoluble or only partially soluble; c) if necessary, drying the active material matrix; d) washing out the pore former (3) by treating the active material matrix with the solvent and e) Introducing an active material into the generated pores of the active material matrix. [2] The method according to claim 1, wherein the pore former (3) comprises a salt. [3] The method according to claim 2, wherein the pore former (3) comprises sodium chloride, potassium chloride or barium acetate. [4] Method according to one of claims 1 to 3, wherein the pore former (3) comprises particles having a size in a range of greater than or equal to 0.01 µm to less than or equal to 50 µm, in particular greater than or equal to 0.1 µm to less than or equal to 30 µm. [5] Method according to one of claims 1 to 4, wherein the pore former (3) is present in the active material matrix in a concentration in a range from greater than 0 wt.% to less than or equal to 30 wt.%. [6] The method according to claim 5, wherein an active material matrix is ​​applied to the base body, comprising: greater than or equal to 5 wt% to less than or equal to 80 wt% sulfur, greater than or equal to 5 wt% to less than or equal to 90 wt% SPAN, greater than or equal to 2.5 wt.% to less than or equal to 90 wt.% conductive additive, greater than or equal to 2.5 wt% to less than or equal to 50 wt% binder, greater than 0 wt.% to less than or equal to 30 wt.% pore former and greater than or equal to 30 wt% to less than or equal to 95 wt% solvent. [7] Method according to one of claims 1 to 6, wherein an electrode is produced which has a thickness in a range of greater than or equal to 20µm to less than or equal to 200µm. [8] Method for producing an electrochemical energy storage device, in particular a lithium-ion battery, comprising a method according to one of claims 1 to 7. [9] Electrode comprising a base body, which is designed in particular as a current collector, and an active material matrix arranged on the base body, wherein the active material matrix comprises a binder, an active material (1) and optionally a conductive additive, wherein a defined porosity is provided in the active material matrix, the pores of which are at least partially shaped according to a crystal and wherein an active material is introduced into the pores of the active material matrix. [10] Electrochemical energy storage device, in particular a lithium-ion battery, comprising an anode, a cathode and an electrolyte arranged between the anode and the cathode, wherein the energy storage device has at least one electrode, in particular a cathode, according to claim 9.

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