Battery cell and battery

Abstract

The invention relates to a single battery cell (101) with an electrode winding (102) which is continuously connected along the length of its electrodes in the winding direction or at a plurality of points to a respective pole of the single battery cell (101), with a housing (107) which has a venting opening (106). The invention is characterized in that mechanical retaining elements (111, 112) are arranged in the area of ​​the venting opening (106) which retain at least parts of the electrode winding (102) in the event of an overpressure-induced opening.

Description

[0001] The invention relates to a single battery cell with an electrode coil according to the type defined in more detail in the preamble of claim 1. Furthermore, the invention relates to a battery with such single battery cells. The invention also relates to a vehicle with such a battery.

[0002] Individual battery cells with electrode coils are well known in the art. The term "tabless" is used in English and now also in German to describe individual battery cells with electrode coils. These cells have electrode coils where the electrode coil is not electrically connected directly or indirectly to the respective pole of the individual battery cell at the inner and outer ends of the coil, but rather where the end faces of the coils are connected to the respective poles via projecting elements of the individual electrodes. The purpose of this design is to reduce electrical resistance, as the current only has to travel the height of the coil and not the entire length of the electrode before being conducted to the poles. This can lead to considerable savings in internal resistance.

[0003] Such individual battery cells are fundamentally known from the state of the art and are described, for example, in WO 2020 / 096973 A1.

[0004] Furthermore, it is fundamentally known from the prior art that the electrode coils of such individual battery cells are installed in housings. In the case of round cells, these housings can be cup-shaped, usually deep-drawn aluminum, which simultaneously forms one pole of the individual battery cell, while a housing cover forms the other pole and is typically connected, for example, welded, to the copper electrodes of the electrode coil. Furthermore, a so-called venting opening is provided within these individual battery cells or in their housing. In the event of thermal runaway in an individual battery cell, the pressure within it increases. This pressure is dissipated via the venting opening, preventing the individual battery cell from bursting.The venting opening can comprise a cover secured to the housing via a predetermined breaking point, or it can be formed by a predetermined breaking point surrounding the housing. In the event of excess pressure, a portion of the housing tears away, forming a venting opening. Hot gases and / or particles flow out of the housing along with the escaping excess pressure. This increases the safety of the structure.

[0005] The object of the present invention is to further improve such a single battery cell so that in the event of thermal runaway of the single battery cell within a battery, it transfers as little thermal energy as possible to neighboring single battery cells.

[0006] This object is achieved by a single battery cell having the features in claim 1, and in particular in the characterizing part of claim 1. Advantageous embodiments and refinements emerge from the dependent subclaims. Furthermore, a battery with such single battery cells according to claim 6 achieves the object. Advantageous embodiments emerge from the dependent subclaim. Furthermore, a vehicle with one of these batteries according to claim 8 also achieves the object.

[0007] The inventor's internal investigations into such individual battery cells revealed the following pattern regarding thermal runaway. In the event of overpressure within the housing of the individual battery cell, the venting opening would open, for example, by the lower part of the housing being blown off. Along with the hot gases and the overpressure, a portion of the electrode coil would often be expelled, while another portion, opposite the venting opening, remained within the housing. The pressure therefore evidently caused the individual separator and electrode foils within the coil to tear, causing it to split in its axial direction relative to the axis around which the materials are unwound.

[0008] Depending on the concept by which the individual battery cells are assembled into a battery or battery module and cooled within it, it may be useful to retain the electrode coil and the heat emanating from it or stored in it in order to prevent thermal runaway from spreading to neighboring individual battery cells.

[0009] The solution according to the invention therefore provides for retaining elements to be arranged in the region of the venting opening of the housing of the individual battery cell according to the invention, which retain the electrode coil in the case of an opening due to overpressure. The retaining elements thus ensure that gases and smaller particles can flow out, so that the critical overpressure can be dissipated via the venting opening, as intended. At the same time, the retaining elements ensure that the electrode coil or parts of the electrode coil do not escape into the environment. This essentially retains heat in the area of ​​the housing, since the electrode coil heats up considerably in the event of thermal runaway and has a higher heat capacity than the gases. The heat dissipation into the environment is thus reduced.

[0010] The retaining elements can consist of webs that remain between the partial openings of a venting opening formed from several such partial openings and that accordingly retain the electrode coil. An alternative design, which in principle can also be used in addition, can also provide for the retaining elements to be designed in the form of a grid that holds the electrode coil in the housing, even when the venting opening is open. Various shapes and geometries of this grid can be used. For example, different openings can be adapted to the corresponding cell chemistry of the respective cell so that only the portion of the gases and particles that are intended to reach the environment actually reaches the environment, and the others are retained in the housing.Furthermore, when dimensioning the retaining elements, care must be taken to ensure that their openings do not become blocked, so that gases can continue to be released and the cell can be reliably prevented from bursting.

[0011] Such a single battery cell can now, together with other single battery cells, form a battery or a battery module of a battery constructed from such battery modules. This variant of the single battery cell, in which materials are retained in the housing in the event of a thermal problem, is particularly suitable for use in batteries in which a coolant flows around the individual battery cells. This coolant can be, for example, a cooling oil. Batteries of this type, in which the individual battery cells are arranged in liquid cooling oil, are common, for example, in high-performance batteries such as those used in sports cars or in motor racing. In the event of thermal runaway in one of the individual battery cells, the coolant can absorb a large amount of heat, thus preventing neighboring individual battery cells from heating up and thus a thermal chain reaction.This works particularly well when the heating material and thus the heat source largely remains in the single battery cell, which is achieved by the structural design of the single battery cell with the retaining elements in the area of ​​the venting opening.

[0012] The electrode coils of the individual battery cells according to the invention can be arranged in any housing shape, in principle even in largely prismatic or oval housings. They are particularly suitable for use in round cell housings, so the individual battery cells are preferably designed as round cells.

[0013] According to a very advantageous further development, these round cells can have a circumferential predetermined breaking point in the base area, so that in the event of excess pressure, the base is completely blown off in order to reduce the pressure.

[0014] Such batteries are now particularly suitable for use in vehicles to provide electrical drive power in an at least partially electrically powered vehicle, i.e. an electric vehicle or hybrid vehicle.

[0015] Further advantageous embodiments of the individual battery cell according to the invention also result from the exemplary embodiments of individual battery cells and batteries, which are explained below with reference to the figures.

[0016] Showing: Fig. 1 a section of a battery with individual battery cells in the event of thermal runaway of one of the individual battery cells; Fig. 2 a detail of a possible embodiment of a single battery cell; and Fig. 3 the detail according to Fig. 2 in an alternative design.

[0017] In the presentation of the Fig. Figure 1 shows a section of a battery 100. It shows three individual battery cells 101. These are constructed using so-called tableless technology. The individual battery cells 101 comprise electrode windings 102, indicated in the middle of the illustrated individual battery cells 101. The individual battery cells 101 are contacted at their respective poles via electrical contact elements 103 and are held within a battery housing 104 of the battery 100. A cooling fluid 105, in this case a cooling oil, flows through this battery housing 104. The battery 100 is therefore based on the concept of immersion oil cooling.

[0018] If thermal runaway occurs in one of the individual battery cells 101, for example, the single battery cell 101 shown in the center, this can lead to an uncontrolled chain reaction in which heat is dissipated to the neighboring single battery cells 101. The thermal runaway of the individual cell is referred to as thermal runaway, and the uncontrolled chain reaction is referred to as thermal propagation. The requirement, typically a legal requirement, is that, for safety reasons, the thermal runaway of an individual battery cell 101 must not lead to thermal propagation of the entire battery 100.

[0019] It is now common and usual to provide a so-called venting opening 106 in the event of a thermal runaway. This can be implemented, for example, via one or more sections 108 of a housing 107 of the individual battery cell 101, which are connected to the rest of the housing 107 via predetermined breaking points 109. The purpose of this venting opening 106 is to expel the hot gases under excess pressure from the interior of the housing 107 of the individual battery cell 101 in the event of a thermal runaway, in order to relieve pressure and prevent an uncontrolled bursting of the individual battery cell 101 or its housing 107. In the illustrated embodiment, this venting opening 106 is to be arranged at the bottom during intended use, which is a generally customary and typical design.

[0020] The hot gases are then released through this venting opening 106 into the cooling oil 105, with the venting gas flow at least partially displacing the cooling oil 105, so that the neighboring individual battery cells 101 are exposed to a larger surface area of ​​gas, particles, and molten material. This leads to a strong convective heat input into the neighboring individual battery cells 101, particularly in their lower region, i.e., in the region that is comparatively close to the venting opening 106 of the neighboring individual battery cell 101 affected by the thermal runaway. At the same time, the individual battery cells 101 on the opposite side remain relatively well cooled by the cooling oil, so that even larger amounts of heat can be dissipated relatively easily.

[0021] In order to prevent the thermal runaway of one of the individual battery cells 101 from spreading to the neighboring individual battery cells 101 and thus becoming thermal propagation, it is particularly sensible in this design of the battery 100 to retain as much material and thus as much heat as possible within the housing 107 of the individual battery cell 101. In the embodiment shown here, this is achieved, for example, by a design in which the venting opening 106 has several partial openings. In the illustration of the Fig. 2 shows such a structure in a view of the housing 107 of the individual battery cell 101 from below. The bottom 110 of the housing 107, visible here, has four individual sections, each designated 108, which are connected to the bottom 110 via circumferential predetermined breaking points 109. In the event of excess pressure, the four individual sections 108 tear open accordingly. The webs 111, made of greater material thickness, remain between them. This largely prevents the discharge of materials from the interior of the housing 107, so that only gases and smaller particles flow out, while the electrode coil 102, which has a high heat capacity, is retained in the housing 107 by the webs 111.A large part of the heat remains in the individual battery cell 101 affected by the thermal runaway, shown here in the middle, and can thus be carried away comparatively easily by the cooling oil 105, so that the liquid cooling of the hot housing 107 achieves a far better dissipation of waste heat than if a large part of the material escapes, displaces the cooling oil 105 and flows directly onto the adjacent individual battery cells 101.

[0022] An alternative to the bars 111 is shown in the illustration of the Fig.3. The venting opening 106 here does not consist of individual sections 108, but of a larger section that tears off as a whole. It can also be the lower part of the housing 107 or the entire bottom 110 of the housing 107. In order to retain the materials of the electrode coil 102 in the housing 106, a grid designated 112 is provided here, which can, for example, be pressed into the housing 107. It is made of a material that is sufficiently temperature-stable to reliably retain the electrode coil 102 even in the event of a thermal runaway.

[0023] The mesh size of the grid 112 or the size of the sections 108 between the webs 111 must be selected such that a sufficient amount of gas can escape from the housing 107 without too much of the material contained in the housing 107 escaping. At the same time, the size must be selected such that the material of the electrode coil 102 does not clog the openings, preventing the gas from escaping and causing the housing 107 of the single battery cell 101 to burst as a whole. List of reference symbols 100 batteries (first type) 101 single battery cell (first type) 102 electrode coils 103 contact elements 104 Battery housing 105 Coolant / Cooling oil 106 Venting opening 107 cases out of 101 108 sections 109 predetermined breaking points 110 Floor 111 bridges 112 grids QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2020 / 096973 A1

[0003]

Claims

[1] Single battery cell (101) with an electrode winding (102) which is connected to a respective pole directly or indirectly over the length of its electrodes in the winding direction or at a plurality of points, with a housing (107) which has a venting opening (106), characterized by that mechanical retaining elements (111, 112) are arranged in the region of the venting opening (106), which retain at least parts of the electrode coil (102) in the event of an opening in the housing (107) due to excess pressure. [2] Single battery cell (101) according to claim 1, characterized by that the venting opening (106) consists of several sections (108), between which webs (111) remain even in the event of the venting opening (106) being opened and serve as retaining elements. [3] Single battery cell (101) according to claim 1 or 2, characterized by that the retaining elements are designed in the form of an inserted grid (112). [4] Single battery cell (101) according to one of claims 1 to 3 characterized by their formation as round cells. [5] Single battery cell (101) according to one of claims 1 to 4, characterized by that the housing (107) has at least one predetermined breaking point (109) running around a partial section to form the venting opening (106). [6] Battery (100) with a plurality of individual battery cells (101) according to one of claims 1 to 5, wherein the individual battery cells (101) are completely or partially surrounded by a cooling liquid (105). [7] Battery (100) according to claim 6, characterized by that the cooling liquid (105) is designed as cooling oil. [8] Vehicle with a battery (100) according to one of claims 6 or 7, with an at least partially electric drive.

Images