Method for manufacturing a solids separator

Abstract

The invention relates to a method (34) for producing a solid-state separator (16). In this method, a metal foil (24) is provided and heated. A solid electrolyte powder (52) is applied to the heated metal foil (24), wherein, during application, the heated metal foil (24) has a temperature higher than the melting point of the solid electrolyte (26).

Description

[0001] The invention relates to a method for manufacturing a solid-state separator and a method for manufacturing a solid-state battery.

[0002] Increasingly, motor vehicles are being powered, at least partially, by an electric motor, resulting in electric or hybrid vehicles. A high-voltage battery, typically comprising several individual battery modules, is used to power the electric motor. These battery modules are usually identical in construction and electrically connected in series and / or parallel, so that the voltage applied to the high-voltage battery is a multiple of the voltage provided by each individual battery module. Each battery module, in turn, contains several batteries, usually housed in a common module casing, which are also electrically connected in series and / or parallel.

[0003] Each battery typically comprises several galvanic cells. These cells each have two electrodes, namely an anode and a cathode, as well as a separator between them and an electrolyte containing freely moving charge carriers. A liquid, for example, is used as such an electrolyte. The anode and cathode, which form the battery's electrodes, usually enclose a support that acts as a current collector. An active material is typically attached to this support; this active material is a component of a layer applied to the support, also known as the current collector. The electrolyte may already be present in this layer, or it may be added subsequently. At a minimum, however, the active material is suitable for absorbing the working ions, such as lithium ions.Depending on its use as an anode or cathode, a different material is used for the substrate and a different type of layer material.

[0004] Alternatively, the battery is designed as a solid-state battery, with the electrolyte in solid form. In this case, the separator and the solid electrolyte can be formed by means of a common layer located on one of the current collectors. This current collector is associated with the anode, and as long as the battery is not charged, the layer is in direct contact with the current collector. When the battery is charged, work ions, such as lithium ions, are deposited between the current collector and the layer and then leached out of the layer.

[0005] Typically, the manufacturing process begins with the production of a green compact from a solid electrolyte powder, which is then sintered. This involves heating and pressing the green compact. The resulting ceramic membrane, which forms the core layer, is then attached to a metal foil that acts as a current collector. A disadvantage of this method is that the production of the ceramic membrane—namely, the heating and pressing—is relatively energy-intensive, resulting in comparatively high manufacturing costs for such a battery. Furthermore, the heating and pressing processes can locally disrupt the homogeneity of the solid electrolyte powder, leading to defects such as dendrites, which can cause a short circuit in the battery. Additionally, the ceramic membrane must be self-supporting, resulting in relatively thick layers, typically exceeding 30 µm.Only with such a large thickness is it possible to securely bond the layer to the metal foil without damaging the layer.

[0006] The invention is based on the objective of providing a particularly suitable method for manufacturing a solid-state separator and a particularly suitable method for manufacturing a solid-state battery, wherein advantageously a reject rate and / or a size of the product are reduced, and wherein a manufacturing time and / or manufacturing costs are reduced.

[0007] With regard to the method for manufacturing a solid-state separator, this problem is solved according to the invention by the features of claim 1, and with regard to the method for manufacturing a solid-state battery, by the features of claim 10. Advantageous further developments and embodiments are the subject of the respective dependent claims.

[0008] The process serves to manufacture a solid-state separator and is suitable, in particular designed and configured, for this purpose. The solid-state separator is suitable, in particular designed and configured, to form a solid-state battery. In other words, it is possible to use the solid-state separator to manufacture the solid-state battery. The solid-state battery advantageously also includes a cathode attached to the solid-state separator. In particular, the solid-state separator and the cathode together form the solid-state battery. Alternatively, the solid-state battery may, for example, comprise several such assemblies of solid-state separators / cathodes, which are, for example, stacked on top of each other, in particular to form a so-called "stack," or rolled up, in particular to form a so-called "jelly roll."

[0009] The solid-state battery is designed to be rechargeable and is expediently a secondary battery. Preferably, the solid-state battery is a component of a motor vehicle in its intended state. The solid-state battery is suitable, specifically designed and configured for this purpose. In its intended state, the solid-state battery is, for example, a component of a motor vehicle energy storage system that includes several such solid-state batteries. Preferably, the solid-state batteries are divided into several battery modules, which are identical in construction. The solid-state batteries are arranged, in particular, in a housing of the energy storage system or the respective battery module and are electrically connected in parallel and / or in series. Thus, the electrical voltage applied to the energy storage system / battery module is a multiple of the electrical voltage provided by each of the solid-state batteries.Conveniently, all solid-state batteries are identical in construction, which simplifies manufacturing.

[0010] The motor vehicle is preferably land-based and preferably has a number of wheels, at least one, preferably several or all, of which are driven by a drive system. In particular, one, preferably several, of the wheels is designed to be steerable. This makes it possible to move the motor vehicle independently of a specific roadway, such as rails or the like. It is advantageously possible to position the motor vehicle essentially arbitrarily on a roadway, which is made, in particular, of asphalt, tar, or concrete. The motor vehicle is, for example, a commercial vehicle such as a truck or a bus. However, it is particularly preferred that the motor vehicle be a passenger car. Alternatively, the motor vehicle is, for example, a boat, an airplane, a helicopter, a multicopter, a bicycle (pedelec), a motorcycle, or a spacecraft.

[0011] The drive system expediently propels the motor vehicle. For example, the drive system, particularly the main drive, is at least partially electric, and the motor vehicle is, for instance, an electric vehicle. The electric motor is powered, for example, by means of the energy storage device, which is suitably designed as a high-voltage battery. The high-voltage battery expediently provides a direct current voltage, the voltage being, for example, between 200 V and 800 V, and, for example, substantially 400 V. Preferably, an electrical converter is arranged between the energy storage device and the electric motor, by means of which the current supplied to the electric motor is adjusted. Alternatively, the drive system also includes an internal combustion engine, so that the motor vehicle is designed as a hybrid vehicle.Alternatively, the energy storage device supplies a low-voltage electrical system of the motor vehicle, and in particular provides a direct current voltage of 12 V, 24 V or 48 V.

[0012] In another application, the solid-state battery is a component of a forklift, an industrial plant, or a handheld device, such as a power tool, especially a cordless screwdriver. In yet another application, the solid-state battery is part of a power supply system and is used, for example, as a buffer battery. In another application, the solid-state battery is a component of a portable device, such as a mobile phone or other wearable. It is also possible to use such a solid-state battery in camping, model making, or for other outdoor activities.

[0013] According to the method, a metal foil is provided. The metal foil is made of an electrically conductive material, for example, aluminum or, more preferably, copper. Advantageously, the metal foil is flexible and has a thickness of less than 0.1 mm, 0.05 mm, or 0.001 mm. Thus, the metal foil is essentially two-dimensional. In other words, the metal foil has increased dimensions in the other dimensions, each of which is particularly greater than 1 cm.

[0014] In a further step, the metal foil is heated. This may involve heating the entire foil or at least a section of it. As a result, the foil reaches an elevated temperature, but preferably not high enough to melt or soften it. Specifically, the temperature of the metal foil after heating is lower than the melting point of the material from which it is made. This ensures that the metal foil retains its mechanical integrity. Ideally, the temperature of the metal foil after heating should be greater than 400°C, 450°C, or 500°C. Conversely, it should be less than 1200°C, 1000°C, 900°C, or 800°C.

[0015] In a further step, a solid electrolyte powder is applied to the heated metal foil. Before application, the solid electrolyte powder is a powder and therefore a solid. The solid electrolyte powder preferably consists of individual grains. These grains are, for example, made of the same material and have essentially the same grain size, resulting in a homogeneous solid electrolyte powder. Alternatively, the individual grains may have different dimensions, compositions, and / or configurations, and the solid electrolyte powder is therefore inhomogeneous. Preferably, at least one grain diameter is less than 1 mm, more preferably less than 0.1 mm, and particularly less than 10 µm or less than 5 µm. Advantageously, the grain size is greater than 0.1 µm or 1 µm.

[0016] The solid electrolyte powder advantageously consists of or comprises LLZO or LATP. The material of which the solid electrolyte powder consists, or at least comprises, is preferably an inorganic solid electrolyte, and in particular a sulfide and / or oxide solid electrolyte. An inorganic solid electrolyte with a NASICON structure, in particular LATP, LAPG, or LAGTP, an inorganic solid electrolyte with a garnet structure, in particular LLZO, or an inorganic solid electrolyte with a LISICON structure is particularly preferred. Alternatively, an inorganic solid electrolyte with a perovskite or anti-perovskite structure is used. At a minimum, the solid electrolyte powder is advantageously formed from a material that is solid at ambient temperature and / or at temperatures below 100 °C, at least at ambient pressure.

[0017] For example, the solid electrolyte powder is applied to the entire metal foil, or at least to the area that has been heated. When the solid electrolyte powder is applied to the heated metal foil, the temperature of the heated metal foil, at least in the area where the solid electrolyte powder is applied, is higher than the melting point of the solid electrolyte, and in particular of the individual components of the solid electrolyte powder, such as the chemical element or the chemical compound.

[0018] Due to the contact of the solid electrolyte powder with the heated metal foil, the individual grains / particles of the solid electrolyte powder melt, forming a cohesive, partially liquid layer. In other words, the solid electrolyte powder melts upon contact with the heated metal foil and transitions, at least partially, into a liquefied or pasty state. During this process, the individual particles / grains of the solid electrolyte powder at least partially bond together.

[0019] Due to the energy transfer from the metal foil to the solid electrolyte powder, the metal foil cools down. When the liquid solid electrolyte layer also solidifies, particularly due to cooling, a continuous layer of the solid electrolyte forms on the metal foil, adhering to it and creating a metallurgical bond. In summary, a layer of the resolidified solid electrolyte is advantageously formed and applied to the metal foil, adhering to it. Advantageously, the metal foil and the solid electrolyte applied to it constitute the solid separator.

[0020] This process results in a continuous layer of solid electrolyte on the metal foil without the need for applying mechanical force, particularly pressing or sintering. This prevents the formation of defects or inhomogeneities that could lead to defects, thus reducing scrap. Furthermore, it allows for the production of a comparatively thin layer of solid electrolyte on the metal foil, typically between 5 µm and 15 µm thick. This also reduces the overall size of the product.

[0021] The manufacturing process requires only a relatively small number of steps, thus reducing production time and therefore manufacturing costs. The number of components required for the device used to carry out the process is also reduced, further lowering manufacturing costs. The device includes, in particular, a component for supplying the metal foil and a component for heating the metal foil. Furthermore, the device includes a component for applying the solid electrolyte powder. Suitablely, the device also includes a component for transporting the metal foil. The invention also relates to a corresponding device and the use of the device for carrying out the process.

[0022] In summary, the application of the solid electrolyte powder, which forms the solid electrolyte / solid separator in the finished solid-state battery, does not alter its structure, and it is possible to form a comparatively thin layer of solid electrolyte. This requires relatively few work steps / processes. Furthermore, it is possible to apply the solid electrolyte powder only to specific areas of the metal foil, leaving other areas free of the solid electrolyte. This simplifies further processing of the solid separator, particularly its electrical contacting.

[0023] Advantageously, the solid-state separator produced according to the method is used to at least partially form the anode of a solid-state battery. To manufacture the solid-state battery, a cathode is advantageously attached to the solid-state separator, particularly to the solid electrolyte. The cathode suitably has a current collector onto which a further layer is applied, comprising an active material, a conductor, and / or a binder. The active material of the cathode is preferably a positive electrode active material, such as lithium nickel manganese cobalt oxide (LNMC), lithium nickel manganese oxide (LNMO), LiCoPO4, LiNiPO4, LiFePO4, or lithium cobalt oxide (LCO). Preferably, lithium cobalt(III) oxide (LiCoO2), NMC, for example NMC622 or NMC811, NCA, LMNO, or LFP is used. When manufacturing the cathode, an aluminum foil is preferably used as a current collector.

[0024] For example, to heat the metal foil, it is passed through an oven or treated with thermal radiation, for which a laser is used, for instance. Alternatively, the metal foil is heated by exposing it to a hot gas. Another alternative is to heat the metal foil using a roller over which it is passed. In this case, the roller is at a comparatively high temperature, and heat energy is transferred from the roller to the metal foil, causing it to heat up. Alternatively, heating can be achieved, for example, by induction. If the device is used to carry out the process, the component for heating the metal foil is specifically designed accordingly.

[0025] For example, the solid electrolyte powder is applied directly to the metal foil immediately after heating. Alternatively, a specific time interval is observed between heating and application. This interval is chosen such that the temperature of the heated metal foil remains above its melting point when the solid electrolyte powder is applied. For example, the solid electrolyte powder is applied only to one side of the metal foil. However, it is particularly preferred that the metal foil is coated with the solid electrolyte powder on both sides. In this case, the solid electrolyte powder is applied to the two opposite sides of the metal foil simultaneously, or this is done sequentially.

[0026] For example, further process steps are carried out after the application of the solid electrolyte powder. For instance, the still-liquid solid electrolyte, particularly the liquid layer formed from the solid electrolyte powder, is processed. However, it is particularly preferred that the metal foil is cooled after application, especially immediately. The cooling of the metal foil is carried out, for example, directly or by cooling the solid electrolyte. As a result, the liquid solid electrolyte solidifies, and the (solid) electrolyte layer is formed. In particular, the surface of the (solid) electrolyte layer is not processed, so that it is comparatively rough and consequently has a comparatively large surface area. As a result, the bonding of other components there, especially the cathode, is improved.Furthermore, the resistance to the entry / egress of a large number of charge carriers is reduced. In other words, an increased surface area is provided for the entry / egress of charge carriers, especially work ions, from the (solid) electrolyte layer. Additionally, the cooling process ensures that the liquid solid electrolyte solidifies and remains in the desired position. In other words, the position of the liquid solid electrolyte is prevented from changing until it finally solidifies. Thus, essentially all solid separators produced according to this process are identical, and the number of rejects is further reduced.

[0027] For example, cooling can be achieved by exposing the metal foil to ambient temperature. However, cooling is preferably achieved by exposing the metal foil and / or the solid electrolyte to a gas stream, such as ambient air, which reduces manufacturing costs. Alternatively, a noble gas or nitrogen can be used. To cool the metal foil, the gas is guided along the solid electrolyte, which may still be at least partially liquefied or pasty, thereby heating the gas. The gas heated in this way is then suitably used to heat another area of ​​the metal foil, onto which the solid electrolyte powder is subsequently applied. This reduces the energy required to carry out the process. The apparatus suitably includes a component for cooling the metal foil.The component expediently includes a heat exchanger through which, in particular, the heated gas is passed.

[0028] Particularly preferably, any loose solid electrolyte powder remaining after the application of the solid electrolyte powder is removed. The device preferably includes a corresponding component for this purpose. For example, before removal, the metal foil, and thus the solid electrolyte, is first cooled so that it at least partially forms a solid that adheres to the metal foil. Any remaining loose solid electrolyte powder is then removed. Since only the solid electrolyte powder not adhering to the metal foil is removed, subsequent attachment of other components of the solid-state battery, such as the cathode, to the solid separator is facilitated, thereby increasing robustness.For example, to remove loose solid electrolyte powder, the metal foil, and thus also the solid electrolyte on it (i.e., the part adhering to the metal foil as well as the loose solid electrolyte powder), is shaken. In other words, the metal foil is vibrated so that any loose particles of the solid electrolyte powder fall off. Alternatively or in combination with shaking, the metal foil and / or the solid electrolyte applied to the metal foil is subjected to ultrasound, causing it to vibrate. This also removes loose solid electrolyte powder. In a further development, the solid electrolyte is alternatively or additionally exposed to a gas stream / jet, so that the loose solid electrolyte powder is blown away. Advantageously, the metal foil is also cooled by the gas stream, namely via the solid electrolyte.In other words, by exposing the solid electrolyte to the gas stream, the metal foil and the solid electrolyte are cooled on the one hand. On the other hand, the loose solid electrolyte powder is removed in this way.

[0029] For example, the solid electrolyte powder is not further processed before being applied to the metal foil. Alternatively, it is preheated, at least to a temperature above ambient temperature. The device advantageously includes a corresponding component for this purpose. The solid electrolyte powder is suitably heated to a comparatively high temperature, but one that is lower than its melting point. In particular, the temperature is chosen such that the individual particles / grains of the solid electrolyte powder do not clump together. In other words, the temperature is chosen such that the surface of the individual particles of the solid electrolyte powder is not altered, or only minimally so. Thus, the solid electrolyte powder remains in powder form, and its application to the metal foil is not hindered or impeded.Due to the heating of the solid electrolyte powder, only a comparatively small amount of energy is required from the metal foil to the solid electrolyte powder to melt it, thus creating a continuous layer. Therefore, the required temperature for replacing the metal foil is reduced. Furthermore, the reduced temperature difference between the applied solid electrolyte powder and the metal foil prevents a sudden cooling of the foil, which reduces stress on the metal foil and thus prevents its destruction. This also prevents mechanical stresses between the metal foil and the solid electrolyte layer. Additionally, the molten solid electrolyte powder remains in a liquid state for a longer period, ensuring the formation of a continuous layer. This also reduces the amount of scrap.If the metal foil is cooled by means of a gas stream, the solid electrolyte powder is heated, for example, by means of the heated gas stream.

[0030] For example, the metal foil is provided in sheets. In this case, the entire sheet of metal foil is heated, and the solid electrolyte powder is applied to it in a single step. However, it is particularly preferred that the metal foil is provided as a strip, and the solid electrolyte powder is applied continuously. In this case, the strip is initially wound up and then successively unwound. The strip is advantageously moved to a heating area. Subsequently, the strip is moved to another area where the solid electrolyte powder is applied. Advantageously, the metal foil coated with the solid electrolyte is then wound up, so that the solid separator is available as a rolled-up strip.In this way, the different process steps are carried out in different areas, which simplifies the design of the device. If the device is used to perform the process, it suitablely includes a winder and / or unwinder for the metal foil. This also enables continuous production of the solids separator. The amount of solids separator produced can be adjusted by selecting the unwinding speed of the metal foil.

[0031] In one embodiment, the metal foil is immersed in a bath supplied by the solid electrolyte powder. This results in a comparatively large quantity of solid electrolyte powder being present, which is melted in the area of ​​direct contact with the metal foil, causing it to adhere to the foil. Due to the large quantity, the formation of a continuous layer is ensured, without the need for a comparatively complex adjustment of the quantity of solid electrolyte powder supplied. This increases robustness.

[0032] For example, the metal foil is guided directly through the bath. This ensures that its entire circumference is coated with the solid electrolyte powder. However, it is particularly preferred that the metal foil is guided over a deflecting roller. In this case, the metal foil is present, in particular, as a strip, and the deflecting roller changes the feed direction of the metal foil. The deflecting roller immerses the metal foil in the bath. In other words, the deflecting roller guides the metal foil into the bath, especially along its surface. Consequently, the metal foil is guided towards the bath up to the deflecting roller, and the deflecting roller changes the feed direction of the metal foil so that it is conveyed away from the bath. In the area of ​​the deflecting roller, the metal foil comes into contact with the solid electrolyte powder, causing the powder to melt and consequently adhere, at least partially, to the metal foil.For example, the metal foil is heated by means of the deflecting roller, resulting in a comparatively compact device for carrying out the process. Alternatively, the metal foil is heated before it reaches the deflecting roller. Preferably, the deflecting roller has no direct mechanical contact with the bath, so that it remains free of the solid electrolyte. Consequently, its circumference remains smooth, thus preventing the formation of creases or other irregularities in the metal foil as it passes over the deflecting roller. The requirement or consumption of solid electrolyte powder is also reduced. For example, the solid electrolyte powder is applied to both sides of the metal foil as it is fed into the bath, or, more preferably, only to one side, which simplifies the design of the device.For example, the metal foil coated on one side with the solid electrolyte is subsequently reheated, and the side of the metal foil free of the solid electrolyte is immersed in the bath or another bath of solid electrolyte powder. Particular care is taken to ensure that the solid electrolyte already adhering to the metal foil is not remelted.

[0033] In an alternative embodiment, the metal foil is positioned above the bath and moved, for example, onto the surface of the bath or, preferably, along its surface. In this way, the surface of the bath is melted by means of the metal foil, and the molten solid electrolyte, adhering to the metal foil, is removed from the bath by means of the metal foil. Particularly preferably, a force is exerted on the solid electrolyte powder in the direction of the metal foil, so that it is pressed against the metal foil. This ensures that the heated metal foil is in mechanical contact with the solid electrolyte powder, thus enabling the molten solid electrolyte powder to adhere to it. For example, the metal foil is arranged essentially horizontally.Alternatively, the foil is inclined so that the surface of the bath, defined by the metal foil, is also inclined. This allows for adjustment of the force acting between the solid electrolyte powder and the metal foil, as well as the reaction zone between the solid electrolyte powder and the metal foil. Consequently, it is possible to adjust the thickness of the resulting layer of solid electrolyte adhering to the metal foil with relative precision. Specifically, the metal foil is moved in a longitudinal direction along which the bath extends. In the transverse direction, the bath has a smaller extent than the metal foil. In this transverse direction, the metal foil may, for example, extend only on one side or, preferably, on both sides beyond the bath.When the solid electrolyte powder is pressed against the metal foil, particularly vertically from below, it is possible that the powder will not be completely melted onto the foil. This excess powder can then escape laterally over the edge of the bath and, due to gravity, fall vertically downwards, preferably to a collection device connected to the bath via a fluid system. Specifically, the collected powder is then returned to the bath. Thus, the unused powder is reintroduced into the process, reducing the overall demand. With this type of device design, a relatively large quantity of the powder can be applied to the metal foil, ensuring the formation of a continuous layer.The unused, excess solid electrolyte powder is not wasted but can be reused. Furthermore, this design keeps the metal foil free of the solid electrolyte, thus simplifying electrical contact.

[0034] In an alternative embodiment, the metal foil is sprayed with the solid electrolyte powder. For this purpose, the device advantageously includes a sprayer / nozzle as a component. Spraying is carried out, for example, using a gas or without gas. Suitablely, the solid electrolyte powder is at least partially atomized for spraying. Because of the spraying process, no direct mechanical contact between the metal foil and the component used to apply the solid electrolyte powder is required. This increases flexibility and simplifies the design of the device. Mechanical stress on the metal foil is also avoided, thus reducing rejects. Furthermore, this method makes it possible to apply the solid electrolyte powder to both sides of the metal foil.This can be done simultaneously or sequentially, and it is not necessary for the solid electrolyte powder and / or the metal foil to come into contact with other components of the device, which could otherwise lead to damage. Spraying also makes it possible to apply the solid electrolyte powder only to specific areas of the metal foil. This allows certain areas of the metal foil to be left free of the solid electrolyte powder, enabling electrical contact with the solid separator in those areas. In particular, the metal foil can be positioned horizontally, vertically, or at an angle in between during spraying. By selecting the angle, the reaction zone and reaction time of the metal foil with the solid electrolyte powder can be adjusted, thus determining the thickness of the (solid) electrolyte layer to be formed.Preferably, the metal foil is supplied as a strip, and the solid electrolyte powder is applied to it essentially continuously by spraying. This enables the continuous production of the solid separator, reducing effort and simplifying the design of the apparatus used for the process. Furthermore, after the metal foil stops moving—for example, due to a strip change, a break, equipment maintenance, or a tear in the foil—no remelting or other time-consuming preparation of the solid electrolyte powder is required, thus reducing downtime. In summary, spraying the heated metal foil with the solid electrolyte powder further reduces production time, and the necessary apparatus components can be designed to be comparatively inexpensive.This further reduces manufacturing costs. Furthermore, the spraying process allows for relatively precise adjustment of the resulting thickness of the solid electrolyte layer to which a metal foil adheres.

[0035] The other method is used to manufacture a solid-state battery. First, a solid-state separator is created. For this purpose, a metal foil is heated. A solid electrolyte powder is applied to the heated metal foil, with the foil being at a temperature higher than the melting point of the solid electrolyte during application. The metal foil and the solid electrolyte thus form the solid-state separator. The solid electrolyte, which melts due to the heating of the metal foil, is then cooled. A cathode is attached to the solid-state separator. The cathode preferably has a current collector onto which another layer is applied, containing an active material, a conductive material, and / or a binder.The active material of the cathode is preferably a positive electrode active material, such as lithium nickel manganese cobalt oxide (LNMC), lithium nickel manganese oxide (LNMO), LiCoPO4, LiNiPO4, LiFePO4, or lithium cobalt oxide (LCO). Preferably, lithium cobalt(III) oxide (LiCoO2), NMC, for example NMC622 or NMC811, NCA, LMNO, or LFP is used. An aluminum foil is preferably used as the current collector of the cathode. Advantageously, the cathode is arranged such that the solid electrolyte and the further layer are located between the current collector and the metal foil. For example, the solid-state battery is formed by means of the solid-state separator and the cathode. Alternatively, only one galvanic unit of the solid-state battery is formed by means of this, and the solid-state battery has a plurality or multiple of such galvanic cells, which are, for example, stacked on top of each other.

[0036] The invention further relates to a solid-state separator / solid-state battery produced according to the corresponding method. The invention further relates to a motor vehicle, such as a passenger car, with such a solid-state battery, in particular such a system. The solid-state battery is used in particular to power a main drive system of the motor vehicle.

[0037] The advantages and further developments described in connection with the two processes can also be applied analogously to the solid-state separator / the solid-state battery / the device / the use / the motor vehicle, as well as to each other and vice versa.

[0038] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. The drawing shows: Fig. 1. Schematically simplified, a motor vehicle that has several identical solid-state batteries, Fig. 2. Schematically shown in a sectional view of one of the solid-state batteries, Fig. 3 a method for manufacturing the solid-state battery, comprising a method for manufacturing a solid-state separator, Fig. Figure 4 schematically simplifies a device for manufacturing the solids separator, and Fig. 5, Fig. 6 each shows a partial modification of the device.

[0039] Corresponding parts are marked with the same reference symbols in all figures.

[0040] In Fig. Figure 1 schematically simplifies the representation of a motor vehicle 2 in the form of a passenger car. The motor vehicle 2 has a number of wheels 4, at least some of which are driven by a drive 6 comprising an electric motor. Thus, the motor vehicle 2 is an electric vehicle or a hybrid vehicle. The drive 6 includes an inverter that supplies power to the electric motor. The inverter of the drive 6, in turn, is powered by an energy storage device 8 in the form of a high-voltage battery. For this purpose, the drive 6 is connected to an interface 10 of the energy storage device 8, which is integrated into an energy storage housing 12 of the energy storage device 8, made of stainless steel.

[0041] Within the energy storage housing 12 of the energy storage unit 8, several identical battery modules (not shown in detail) are arranged, each comprising several solid-state batteries 14. The solid-state batteries 14 of each battery module are partially connected electrically in series and partially in parallel. Some of the battery modules are connected electrically in series, and these in turn are connected electrically in parallel. The electrical connection of the battery modules is electrically contacted via the interface 10, so that during operation of the drive 6, the battery modules, and thus also the solid-state batteries 14, are discharged or charged (recuperated).Due to the electrical interconnection, the electrical voltage provided at interface 10, which is 400 V, is a multiple of the electrical voltage provided by each of the battery modules and also by each of the solid-state batteries 14.

[0042] In Fig. Figure 2 shows a cross-sectional view of one of the structurally identical solid-state batteries 14. The solid-state battery 14 has several solid separators 16 and cathodes 18, of which only two are shown. The cathodes 18 have a current collector 20, also referred to as a current collector. These are each formed by an aluminum foil, which is provided on both sides with an additional layer 22. The additional layer 22 consists of an active material, such as LFP, a binder, and a conductive additive. The separators 16 each have a metal foil 24, both sides of which are provided with a layer of a solid electrolyte 26. The thickness of the solid electrolyte 26 layer is 10 µm. The solid separators 16 and the cathodes 18 are stacked alternately on top of each other, and all metal foils 24 and all current collectors 20 are each electrically contacted with a busbar 28.These are guided through a housing 30 within which the stack of solid separators 16 and cathodes 18 is arranged.

[0043] The solid-state battery 14 contains no liquid components, and during charging, an electrical voltage is applied to the two busbars 28. As a result, work ions, namely lithium ions, flow from the outer layer 22 through the solid electrolyte 26 towards the metal foil 24 and are deposited there. During discharge of the solid-state battery 24, however, the work ions are moved away from the metal foil 24, so that the solid electrolyte 26 is again in direct contact with it.

[0044] In Fig. Figure 3 shows a process 32 for the production of the solid-state battery 14. The process 32 for the production of the solid-state battery 14 begins with a process 34 for the production of the solid-state separator 16, for which a Fig. 4. A schematically simplified device 36 is used. In the process 34 for manufacturing the solids separator 16, a first work step 38 is carried out in which a strip 40 of the metal foil 24 is provided, which is unwound by means of a dispenser 42 and guided in the direction of a deflecting roller 44.

[0045] On its way there, the metal foil 24, which is a copper foil, is guided past a first component 46 of the device 36. In a second step 48, the metal foil 24 is heated by means of the first component 46. For this purpose, the metal foil 24 is exposed to hot ambient air by means of the first component 46, so that the metal foil 24 is heated. Subsequently, the temperature of the metal foil 24 is increased, but it is lower than the melting point of the copper foil, so that the mechanical integrity of the metal foil 24 is maintained.

[0046] In a third step 50, which occurs essentially simultaneously, a solid electrolyte powder 52, held in a dish 54, is heated. For this purpose, a heating device 56, such as a heating coil, is arranged in the dish 54. A bath 54 is formed by means of the solid electrolyte powder 52 arranged in the dish 54, and the temperature of the solid electrolyte powder 52 remains below its melting point. Thus, the solid electrolyte powder 52 in the bath 58 remains in the same state of matter.

[0047] In a fourth step 60, the solid electrolyte powder 52 is applied to the heated metal foil 24. For this purpose, the metal foil 24 is guided into the bath 58 provided by means of the solid electrolyte powder 52. The metal foil 24 is guided over the deflecting roller 44, with the metal foil 24 located on the side of the deflecting roller 44 facing the tray 24. Thus, the metal foil 24 is immersed or pressed into the bath 58 by means of the deflecting roller 44. The deflecting roller 44 is arranged such that the solid electrolyte powder 52 does not penetrate to it.

[0048] By means of the heated metal foil 24, which has a temperature above the melting point of the solid electrolyte 26 in the area of ​​the deflecting roller 44, the solid electrolyte powder 52 is partially melted on the surface of the bath 58. The molten solid electrolyte powder 52 adheres to the supplied metal foil 24 and forms a metallurgical bond with it. The metal foil 24 is deflected by the deflecting roller 44 so that the metal foil 24, coated with the molten solid electrolyte powder 52, is moved away from the bath 58. Since the metal foil 24 is unwound essentially continuously by the unwinder 42, heated metal foil 24 is constantly fed in, so that the solid electrolyte powder 52 is continuously applied to the heated metal foil 24.

[0049] The metal foil 24, coated with the at least partially liquefied solid electrolyte powder 52, is transferred to a second component 62, which cools the metal foil 24. For this purpose, the metal foil 24 is exposed to a gas stream, namely ambient air, which causes the solid electrolyte powder 52 applied to the metal foil 24 to solidify, forming the solid electrolyte 26 that is applied to / adheres to the metal foil 24. No further processing of the surface of the solid electrolyte 26 takes place, and the surface facing away from the metal foil 24 is comparatively rough. The ambient air supplied by the second component 62 is heated due to contact with the metal foil 24.The heated ambient air is fed to a heat exchanger connected to the first component 46, so that some of the waste heat provided by the second component 62 can be used to heat the metal foil 24 by means of the first component 46.

[0050] The metal foil 24 is subsequently guided to a third component 64, by means of which, in a fifth step 66, any remaining loose solid electrolyte powder 52 is removed from the formed layer of solid electrolyte 26. For this purpose, the metal foil 24, coated with the solid electrolyte 26, is subjected to ultrasound by the third component 64, causing it to vibrate slightly. This removes the remaining solid electrolyte powder 52 that is not completely melted or at least does not adhere to the metal foil 24. In particular, the third component 64 is arranged such that the removed solid electrolyte powder 52 is returned to the bath 58.

[0051] In a subsequent sixth step 68, the metal foil 24, thus coated with the solid electrolyte 26, is wound up using a winder 70, and the solid separator 16 is completed. In a further step, the metal foil 24 is also cut to the desired length, depending on the design of the solid-state battery 14.

[0052] Following this, process 34 for the production of the solid-state separator 16 is completed. Then, a seventh step 72 of process 32 for the production of the solid-state battery 14 is carried out. In the seventh step 72, one of the cathodes 18 is attached to the produced solid-state separator 16. Due to the rough and thus increased surface area of ​​the solid electrolyte 26, the resistance for the transfer of working ions to the cathode 18 and back is comparatively low.

[0053] In Fig. Figure 5 shows a partial modification of the device 36, in which the unwinder 42, the rewinder 70, and the first, second, and third components 46, 62, 64 remain unchanged. However, instead of the bath 58 and the deflecting roller 44, a fourth component 74 is used to apply the solid electrolyte powder 52 to the metal foil 24. This fourth component has two nozzles 76. The two nozzles 76 are arranged on opposite sides of the metal foil 24, and the solid electrolyte powder 52 is sprayed onto the metal foil 24 by means of these nozzles. In other words, the metal foil 24 is sprayed with the solid electrolyte powder 52. The fourth component 24 also includes the heating device 56, which is not shown in detail, so that the solid electrolyte powder 52 is already preheated when it hits the metal foil 24, where it is liquefied, so that the continuous layer is formed.Here too, the solid electrolyte powder 52 is continuously applied to the metal foil 24.

[0054] In this variant, a comparatively targeted application of the solid electrolyte powder 52 is possible, and it is possible to leave certain areas of the metal foil 24 free of the solid electrolyte powder 52 and thus of the solid electrolyte 26, thereby simplifying electrical contact with the busbar 28. In this embodiment, the metal foil 24 is also coated on both sides with the solid electrolyte powder 52. In a variant not shown in detail, only one nozzle 76 is present, and the metal foil 24 is coated with the solid electrolyte powder 52 only on one side.

[0055] In Fig. Figure 6 shows a further embodiment of the device 36 in a sectioned view perpendicular to the longitudinal axis of the metal foil 24, i.e., perpendicular to its direction of movement between the unwinder 40 and the winder 70. The metal foil 24 is arranged above the bath 58, with the tray 54 being, in comparison to the one in Fig. In the variant shown in Figure 4, the metal foil 24 has a reduced dimension in the transverse direction, i.e., perpendicular to the longitudinal direction, such that it protrudes beyond the tray 54 on both sides. The metal foil 24 is moved longitudinally in direct mechanical contact with the solid electrolyte powder 52 located in the tray 54, which is pressed radially upwards against the metal foil 24 by means of an auxiliary device (not shown).

[0056] By means of the metal foil 24, the surface of the bath 58 containing the solid electrolyte powder 52 is melted and, due to the longitudinal movement of the metal foil 24, removed from the bath 58, thereby creating a layer of solid electrolyte 26. Due to the continuous application of the solid electrolyte powder 52 to the metal foil 24, the solid electrolyte powder 52 is continuously deposited onto the metal foil 24. The amount of solid electrolyte powder 52 pressed against the metal foil 24 is greater than the amount that is melted and removed by the metal foil 24. The excess solid electrolyte powder 52 overflows the edge of the bath 54, i.e., in the transverse direction, and is collected by a collection basin 78, which is located below the trays 54 and extends transversely beyond them.The collection basin 78 is connected to the tray 54, and the solid electrolyte powder 42 collected by means of the collection basin 78 is returned there so that it can be pressed against the metal foil 24.

[0057] The invention is not limited to the embodiments described above. Rather, other variants of the invention can also be derived by a person skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the individual embodiments can also be combined with one another in other ways without departing from the subject matter of the invention. Reference symbol list 2 motor vehicles 4-wheeler 6 Drive 8 Energy storage 10 Interface 12 energy storage housings 14 Solid state battery 16 Solid separator 18 Cathode 20 power collectors 22 more shifts 24 metal foil 26 Solid electrolyte 28 busbar 30 cases 32 Methods for manufacturing a solid-state battery 34 Methods for producing a solids separator 36 Device 38 first step Volume 40 42 dispensers 44 Deflection roller 46 first component 48 second step 50 third step 52 solid electrolyte powders 54 bowls 56 Heating device 58 Bath 60 fourth step 62 second component 64 third component 66 fifth step 68 sixth step 70 rollers 72 seventh step 74 fourth component 76 nozzle 78 collection basins

Claims

[1] Method (34) for producing a solid separator (16) wherein - a metal foil (24) is provided, - the metal foil (24) is heated, and - a solid electrolyte powder (52) is applied to the heated metal foil (24), wherein the heated metal foil (24) has a temperature greater than the melting temperature of the solid electrolyte (26) during application. [2] Method (34) according to claim 1, characterized by , that the metal foil (24) is cooled after application. [3] Method (34) according to claim 1 or 2, characterized by , that loose solid electrolyte powder (52) is removed after application. [4] Method (34) according to any one of claims 1 to 3, characterized by , that the solid electrolyte powder (52) is heated to a temperature below the melting temperature before application. [5] Method (34) according to any one of claims 1 to 4, characterized by, that the metal foil (24) is provided as a strip (40), and that the solid electrolyte powder (52) is applied continuously. [6] Method (34) according to any one of claims 1 to 5, characterized by , that the metal foil (24) is introduced into a bath (58) provided by means of the solid electrolyte powder (52). [7] Method (34) according to claim 6, characterized by , that the metal foil (24) is guided over a deflecting roller (44), wherein the metal foil (24) is immersed in the bath (58) by means of the deflecting roller (24). [8] Method (34) according to claim 6, characterized by , that the metal foil (24) is arranged above the bath (58), whereby the solid electrolyte powder (52) is pressed against the metal foil (24). [9] Method (34) according to any one of claims 1 to 5, characterized by , that the metal foil (24) is sprayed with the solid electrolyte powder (52). [10] Method (32) for producing a solid-state battery (14), wherein a solid-state separator (16) is produced according to a method (34) according to any one of claims 1 to 9, and wherein a cathode (18) is attached to the solid-state separator (16).

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