Means of transport, storage system, cell for storing electrical energy and manufacturing process for the cell

Abstract

A means of transport, a storage system, a method for manufacturing a cell (1), and a cell (1) for storing electrical energy are proposed. The cell comprises an electrode terminal (8), a housing (2) with an opening (3), and an electrical insulator (4), wherein the electrode terminal (8) is arranged in the opening (3) of the housing (2) and is insulated from the housing (2) by means of the electrical insulator (4), the electrical insulator (4) comprising a fiber composite material.

Description

[0001] The present invention relates to a storage system, a means of transportation, a cell, and a manufacturing method for such a cell for storing electrical energy. In particular, the present invention relates to an improved short-circuit strength for an electrical cell.

[0002] The electrification of personal transport is currently progressing rapidly. One approach involves manufacturing electrochemical cells as round cells and combining them into storage assemblies for use as traction energy storage devices in vehicles. The round cells comprise a cathode, a separator, an anode, a current collector, an insulator between the current collector and the housing, an external electrode (electrode terminal), and the cell can. The cathode and anode are manufactured as jelly rolls (electrode windings), with a separator separating the two electrodes. To improve the energy output of an electric cell, high current resistance is desired. High currents or high current densities can sometimes cause a significant temperature increase during the charging and / or discharging process. If the generated heat is not dissipated quickly enough, the cell can suffer thermal damage.Therefore, adequate heat dissipation is an important aspect of creating a fast-charging battery cell. To ensure good electrical conductivity, the jelly roll or its connecting tab is welded to the current collection plate or the electrode terminal (usually the positive terminal). However, the positive terminal of the jelly roll (or the current collection plate) must be electrically insulated from the cell casing, as the cell casing usually has the opposite polarity (represents the negative electrode). For this purpose, an insulator disc is inserted between the current collection plate and the casing. In addition, a polymer (plastic) is usually used as an insulator between the jelly roll and the casing. During increased current draw (or current consumption during a fast-charging process), the heat cannot be dissipated as quickly as required due to the frontal insulator between the current collection plate and the casing.In addition, there is a small area available for potential welding processes for the galvanic connection between the external (usually positive) terminal and the current collector plate. Depending on the thermal properties of the insulation material used, heat dissipation could be improved. It is an object of the present invention to alleviate or eliminate the aforementioned disadvantages of the current state of the art.

[0003] The above object is achieved by the features of a cell having the features according to claim 1, a storage network having the features according to claim 9, a means of transport having the features according to claim 10 and a method for producing a cell having the features according to claim 11. The subclaims show preferred developments of the invention.

[0004] The cell is used to store electrical energy and is designed, for example, to be used in a storage network with several (particularly similar) cells as a traction energy store for an electrically powered means of transport. The cell comprises an electrode connection, which is usually provided as the positive pole on the outside of the cell. The electrode connection is provided in an opening in a housing (cell cup or cell lid) and is electrically insulated from the housing by an electrical insulator. The electrode connection is arranged in the opening in the housing or projects through the opening. Electrical contact between the electrode connection on the one hand and the housing or its lid on the other is prevented by a collar of the electrical insulator. Since the electrode connection is inside the housing oron the outside of the housing can have a wider cross-section than its middle section in order to neither fall into nor out of the housing, the electrode connection sections located inside the housing or outside the housing are also electrically insulated from the housing. All of the aforementioned insulation areas can be provided by one and the same electrical insulator, which can undergo deformation, in particular during the manufacturing process. According to the invention and in order to combine the electrical insulation with a sufficiently high thermal conductivity at the same time, the electrical insulator is made of fiber composite material or has fiber composite material. In other words, the electrical insulator contains at least a portion of fibers, which are held together by a material that holds the fibers together (e.g. a polymer or similar).The fibers can have increased thermal conductivity to dissipate the waste heat / process heat generated in the cell through the cell's front end / lid and prevent melting of the electrical insulator or its polymer material. The electrical insulator can seal the cell housing, particularly through the polymer material, by pressing the electrical insulator into the opening between the electrode terminal and the housing. This provides reliable electrical insulation, suitable heat dissipation, and, at the same time, a permanently tight seal for the cell.

[0005] The fiber composite material can, for example, comprise glass fibers or carbon fibers, which typically have a higher thermal conductivity than polymer, thermoplastic, and / or thermoset. The last three materials mentioned can be provided as a further component of the fiber composite material. Alternative or additional fiber materials can include semiconductor material, metal particles, metal fibers, or a combination of the aforementioned fibers. In particular, for semiconductor material, metal particles, and metal fibers, it must be additionally ensured that they do not cause electrical short circuits between the electrode terminal and the housing. The fiber composite material can, in principle, comprise any desired combination of the aforementioned materials, comprising at least one fiber material with a further, in particular plastic-like, binder.

[0006] The fibers of the composite material can preferably be arranged in a predefined position or orientation in the electrical insulator. The fiber composite material therefore preferably has a section within which the fibers are largely contained in an identical orientation. Such an orientation offers the possibility of increasing the thermal conductivity of the fiber composite material in a preferred direction and of using this preferred direction in the cell according to the invention for advantageous properties. In particular, fiber composite materials have increased tensile strength in the direction of the preferred orientation of the fibers contained therein, and tests have also shown that this direction corresponds to increased thermal conductivity. In particular, from the cell interior towards the cell housing orFibers oriented in the cell environment can therefore have a beneficial effect on the heat dissipation properties of the fiber composite material or the electrical insulator.

[0007] The cell can, in particular, be a round cell, so that the electrical energy is stored in an electrode coil commonly referred to as a jelly roll. Round cells typically have an electrode connection in the form of a rivet pin located centrally on a cell lid. The rivet pin is also referred to as a rivet-pin electrode and is particularly designed as a positive electrode. In this function, the electrode connection must be electrically insulated from the housing, which usually represents the negative electrode. Since the rivet-pin electrode orIf the electrode connection is to be at least partially in contact with an inner side of a housing cover and an outer side of a housing cover (preferably at least almost over its entire surface), the cover must be electrically insulated from the electrode connection with regard to the opening, with regard to its inner side and with regard to its outer side and sealed against undesired leakage of electrolyte solution. The electrical insulator can be in contact directly or indirectly (indirectly or indirectly) with the inner side, in the region of the opening, and on the outer side of the cover. The electrical insulator can have a collar which, in the manner of a sleeve or a hollow cylinder, encloses the electrode connection at least in the region of the opening in the housing. The hollow cylinder thus extends coaxially to the rotational axis of symmetry of the round cell in the opening.Within the housing, the electrical insulator can extend as a circular disk parallel to the end face of the jelly roll and parallel to the current collecting plate or parallel to the cover of the housing of the round cell. In this case, particularly thin electrical insulators can be provided because the fiber composite material provides increased strength. Particularly thin electrical insulators can ensure the best possible thermal coupling between the jelly roll and the end face of the housing. In this area in particular, increased proportions of solids / fibers in the fiber composite material are advantageous. If possible, the fibers can be oriented in an axial or coaxial direction in order to conduct the heat directly towards the end face of the housing. In order to achieve particularly high strength orTo achieve tensile strength of the electrical insulator, the fibers or additional fibers can be provided in the radial direction between the current collecting plate and the housing cover.

[0008] The collar preferably does not contain any fibers to prevent deformation of the electrical insulator to form a circular disk-shaped section between the outer side of the housing cover and the outer flange of the electrode terminal. Since heat transfer in the area of ​​the collar or the outer side is not as significant as between the current collecting plate and the inner side of the housing cover, fiber material can be omitted or the proportion of fiber material reduced in favor of reliable and simple production.

[0009] However, if possible and desired, the collar can also have fibers oriented in a predefined manner, which can be coaxial with a main axis of the round cell to ensure good deformability. In other words, the fibers in the area of ​​the sleeve or later outer circular disk can be aligned with the main axis of the round cell, while after the electrode connection has been crimped, they point outward in a radial direction. This increases the tensile strength of the outer circular disk of the electrical insulator and improves heat dissipation from the opening area toward larger radii (toward the cell jacket).

[0010] The fiber composite material can contain metallic fibers or metallic material to increase thermal conductivity. To ensure electrical insulation, an additional electrical insulator should be applied to the electrical insulator. For example, the electrical insulator can be created by dipping or coating with pure polymer or similar. While metallic fibers are provided within the electrical insulator, they do not correspond to the exterior of the electrical insulator. Rather, they are completely encased in a non-electrically conductive material, while providing high thermal conductivity within the electrical insulator.

[0011] According to a second aspect of the present invention, a storage assembly is proposed which can be used, for example, as a traction energy storage device for a means of transport. The storage assembly comprises a plurality of cells according to the first aspect of the invention, which can be arranged, in particular, coaxially to one another, so that passive or active heat dissipation can occur via the aligned end faces. The features, combinations of features, and the resulting advantages clearly correspond to those described in connection with the cell according to the invention, so that, to avoid repetition, reference is made to the above explanations.

[0012] According to a third aspect of the present invention, a means of transportation is proposed, which is particularly designed as an electrically driven means of transportation. It comprises a cell according to the first aspect of the invention and / or a storage system according to the second aspect of the invention. To avoid repetition, reference is made to the above explanations.

[0013] According to a fourth aspect of the present invention, a method for producing a cell according to the first-mentioned aspect of the invention is proposed. The method is presented using a round cell as an example. In a first step, a housing is provided. In addition, an electrode connection (in particular a rivet-pin electrode) and an electrical insulator are provided. The insulator can be inserted into the opening of the housing, for example, from the outside, but alternatively also from the inside. In this case, a flange, which has its contact surface in the insertion direction, is brought into contact with the cover. The electrode connection is then pushed through the electrical insulator. This places the electrical insulator between the electrode connection and the housing.If the electrode terminal is deformed to form an inner and outer flange in the opening, the electrical insulator is also deformed accordingly, forming an inner flange (located between the inner flange of the electrode terminal and the cover) and an outer flange (located between the outer flange of the electrode terminal and the cover). In short, the insulator is inserted into the opening, the electrode terminal is inserted into the insulator, and then the electrode terminal and insulator are pressed together in the opening so that the electrode terminal, in conjunction with the insulator, closes the opening and electrically insulates the cover from the electrode terminal. Adequate thermal coupling between the jelly roll and the cover is ensured by the use of a fiber composite material in the electrical insulator.In particular, the part of the electrical insulator located between the jelly roll and the lid is enriched, constructed, or provided with fiber composite material. This ensures that the electrical insulator in this area exhibits high thermal conductivity, high mechanical strength, and simultaneously low electrical conductivity, while the sealing between the cell housing and the electrode terminal can also be achieved by the electrical insulator.

[0014] The electrical insulator can comprise thermally conductive material, which is achieved in particular through the fiber components. The resulting thermal conductivity can range between 0.1 and 2.0 W / mK (through-plane) and 0.1 to 30.0 W / mK (in-plane). Conventional electrically insulating polymers typically have a thermal conductivity between 0.1 and 0.6 W / mK.

[0015] Further details, features, and advantages of the invention will become apparent from the following description and the figures. They show: Fig. 1 a schematic sectional view of an embodiment of a cell designed according to the invention; Fig. 2 a schematic sectional view of a connection region of an embodiment of a cell designed according to the invention; Fig. 3 a schematic sectional view of a connection area of ​​a further embodiment of a cell designed according to the invention; Fig. 4 a schematic sectional view of a connection area of ​​yet another embodiment of a cell designed according to the invention; Fig. 5 a schematic representation of an embodiment of a means of transport designed according to the invention with an embodiment of a storage network according to the invention; and Fig. 6 a flowchart illustrates steps of an embodiment of a method according to the invention for producing a cell.

[0016] Fig. 1 shows an electrical cell 1 according to an embodiment of the present invention. The cell 1 is designed as a round cell and has a rotational symmetry axis X as the winding axis. A rivet pin is provided concentrically as an electrode connection 8 in a cover of a housing 2. The electrode connection 8 protrudes through the opening 3, within which it is embedded in an electrical insulator 4 and is electrically insulated from the cover. Within the opening, the electrode connection 8 is surrounded by a collar 5 in the form of a hollow cylinder, which at least partially encloses the cover of the housing 2 above or outside as well as below or inside the housing 2. The cover of the housing 2 is electrically insulated from a current collecting plate 12 by an inner plate structure comprising fiber composite material.The current collecting plate 12 is welded to terminal lugs 11 of the jelly roll 9 to establish an electrical connection to the inner flange of the electrode terminal 8. This electrical connection can also comprise a galvanic connection, in particular a welded connection.

[0017] Fig. 2 shows a cover region of an electrical cell according to a first exemplary embodiment, in which the electrical insulator 4 consists only of polymer material in a central region of the collar 5, while a plate-shaped structure 7 between the cover of the housing 2 and the current collecting plate 12 comprises a fiber composite material. This leads to particularly good thermal conductivity of the electrical insulator 4. The same applies to a region of the thermal insulator 4 located between the cover of the housing 2 and an outer flange of the electrode terminal 8. Here, the fibers are now radially aligned, so that they do not hinder the expansion of the electrical insulator 4 during the stamping of the electrode terminal 8.

[0018] Fig. 3 shows a further embodiment of a connection section of a cell according to the invention, in which the current collecting plate 12 has a vertical or coaxial preferred direction with respect to the fiber materials contained therein. In this way, a particularly high thermal conductivity in the vertical direction or towards the end face of the housing 2 can be achieved. The collar 5 comprises only polymer material and is therefore fiber-free. The plate-shaped region of the electrical insulator 4 located between the outer flange of the electrode connection 8 and the cover of the housing 2 has fiber portions oriented in the radial direction, so that no difficulties arise when expanding this region during the stamping of the electrode connection 8.

[0019] Fig. 4 shows a further embodiment of a connection section of a cell 1 according to the invention, in which metallic fiber material or metallic chips are contained in the electrical insulator 4. However, the metallic material portion is not provided in the area of ​​a surface of the electrical insulator 4, but rather forms merely an inner area of ​​the electrical insulator 4, while being coated externally with a purely polymeric layer. In this way, the metallic fibers 14 cannot appear as electrical conductors between the current collecting plate 12 and the cover of the housing 2. A corresponding metallic fiber core is provided in the collar 5 within the opening 3, wherein in this area too, a purely polymeric protective layer on both sides prevents an electrical connection between the cover of the housing 2 and the electrode connection 8.The same applies to the outer flange of the electrical insulator 4, which is produced by widening the electrode connection 8, between the electrode connection 8 and an outer side of the cover of the housing 2.

[0020] Fig. Figure 5 shows an embodiment of a means of transport 10 designed according to the invention, which is electrically driven. An electrochemical storage assembly 13 with coaxially arranged cells according to an embodiment of the present invention is provided in a floor assembly.

[0021] Fig.6 shows steps of an embodiment of a method according to the invention for producing a cell according to the first aspect of the invention. In step 100, an insulator is inserted into an opening in a housing. The insulator has a fiber portion at least in the region of its section arranged within the housing, so that it is designed as a fiber composite material. In step 200, an electrode terminal is inserted into the insulator, so that it is arranged in particular centrally in the cover of the housing. The electrode terminal is now thermally coupled to the cover of the housing on the one hand, while it is electrically insulated from it. Finally, in step 300, the electrode terminal is pressed together with the insulator in the opening. The insulator forms an inner flange and an outer flange, which is arranged between an inner flange of the electrode terminal and the cover of the housing on the one hand, andbetween an outer flange of the electrode terminal and the housing cover on the other hand. Due to the fiber content in the electrical insulator, the electrical insulator is designed as a fiber composite material or comprises fiber composite material. The fiber content significantly increases the thermal conductivity of the electrical insulator, so that process heat generated during (rapid) charging and discharging processes can be dissipated via the end face of the cell considerably faster than is usual in the prior art, and effects conducive to degradation within the cell can be reduced. List of reference symbols: 1 cell 2 housings 3 Opening 4 electrical insulator 5 collars 6 outer plate structure 7 inner plate structure 8 Electrode connection 9 Jelly-Roll Means of Transport 10 11 Connection flags 12 13 Current collecting plate storage network 14 metal fiber core 100 - 300 process steps X winding axis

Claims

[1] Cell (1) for storing electrical energy comprising • an electrode connection (8), • a housing (2) with an opening (3) and • an electrical insulator (4), • wherein the electrode terminal (8) is arranged in the opening (3) of the housing (2) and is insulated from the housing (2) by means of the electrical insulator (4), characterized by , that • the electrical insulator (4) comprises a fiber composite material. [2] Cell according to claim 1, wherein the fiber composite material - Glass fibers and / or - Carbon fibers and / or - Polymer and / or - Thermoplastic and / or - Duroplast and / or - semiconductor material and / or - contains metal particles and / or metal fibers. [3] Cell according to claim 1 or 2, wherein fibers of the fiber composite material are arranged in a predefined position / orientation in the electrical insulator (4). [4] Cell according to one of the preceding claims, wherein the cell (1) is a round cell, the electrode terminal (8) is a rivet-pin electrode and the electrical insulator (4) rests against an inner side of a cover of the housing (2), preferably at least approximately over its entire surface, directly or indirectly, and has a collar (5) which extends at least between the housing (2) and around the electrode terminal (8) in the opening (3). [5] Cell according to claim 4, wherein the collar (5) has no fibers. [6] Cell according to claim 4, wherein the collar (5) has fibers oriented in a predefined manner in the coaxial direction to a main axis (x) of the round cell. [7] Cell according to one of the preceding claims, wherein the fiber composite material comprises metallic fibers and is coated by means of a polymer without fibers. [8] Cell according to one of the preceding claims, further comprising a jelly roll (9), wherein the electrical insulator (4) electrically insulates an end face of the jelly roll (9) or a current collecting plate (12) from the housing (2). [9] Storage array comprising a plurality of cells (1) according to one of the preceding claims. [10] Means of transport comprising a cell (1) according to one of the preceding claims 1 to 8 or a storage network according to claim 9. [11] A method for producing a cell (1) according to any one of claims 1 to 8, comprising the steps: - Provide ◯ an electrode connection (8), ◯ a housing (2) with an opening (3) and ◯ an electrical insulator (4), • Insert the insulator (4) into the opening (3), • Inserting the electrode terminal (8) into the insulator (4), • Pressing the electrode terminal (8) and the insulator (4) into the opening (3), characterized by that the electrical insulator (4) comprises a fiber composite material.

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