Cell contacting system, and battery module and / or pack

Abstract

The invention relates to a cell contacting system (1), by means of which elementary storage cells (2) are electrically connected to each other in series and / or parallel circuits in order to form a battery module or pack, and to a battery module or pack, which is provided for constructing a high-voltage battery system as a device for outputting and storing electrical energy while protecting against excessive current flows. The aim of the invention is to improve a cell contacting system (1). This is achieved in that the fuse element (5) is well thermally insulated from the surroundings.

Description

[0001] Cell contacting system and battery module or pack

[0002] The present invention relates to a cell contacting system by which elementary storage cells are electrically interconnected in series and / or parallel circuits to form a battery module or pack, and to a battery module or pack which is provided for the construction of a high-voltage battery system as a device for supplying and storing electrical energy while being protected against excessive current flows.

[0003] It is known from the prior art that a battery system comprises at least one battery module, and several battery modules can be combined to form a pack. All these units are built from a multitude of elementary storage cells, which are interconnected by a cell contacting system to achieve predetermined electrical connection values ​​for a current flow at a specific voltage and a predetermined electrical storage capacity.

[0004] Battery modules and packs based on such elementary cells or storage cells are designed for use in vehicles and typically feature application-specific formats with the densest possible packing of these elementary storage cells in a generally cylindrical format. Currently common cell formats are known, for example, under the designations 18650, 21700, and 46800. It is known, among other things, from EP 2 008 354 B1 and EP 2 416 405 B1, that electrical fuses are provided in the cell contacting system to safely disconnect even a single elementary storage cell from a current path in the event of an electrical fault and the associated excessive current flows. This prevents overheating from spreading from a single storage cell to the rest of the system in the event of a fault. R.To prevent short circuits in closely spaced memory cells, a safety element, such as a bond wire, is used on each cell. In the cell contacting system, at least one electrical contact to a pole of a basic memory cell is typically designed as an electrical safety element. Such a safety element is designed to irreversibly disconnect the affected cell from the overall system in the event of an overload. This approach can readily be transferred to cuboid-shaped basic memory cells or other memory cell designs.

[0005] For the fuse element to trip reliably, it must represent a bottleneck in the current path connecting a basic storage cell to the cell contact system. This bottleneck, which constitutes the actual fuse element, leads to increased electrical power loss during operation and generates heat that, in the event of a fault above a predetermined current level, causes the fuse element to trip by melting. This inherent additional electrical loss, in turn, reduces the overall efficiency of the battery system.

[0006] The present invention aims to improve a cell contacting system of the type mentioned.

[0007] This problem is solved according to the invention by a cell contacting system in which elementary storage cells are electrically interconnected in series and / or parallel circuits to form a battery module and / or pack, wherein at least one electrical contact to a pole of an elementary storage cell is designed as a safety element in the cell contacting system by the features of claim 1 in that the safety element is thermally well insulated from an environment.

[0008] For a fuse element, an electro-thermal trip is a normal occurrence. The melting or tripping of the fuse element occurs due to a low-resistance short circuit in the battery system, usually a short circuit between the positive and negative terminals of a battery cell. One cause of such a fault can be a metallic part that, for example, becomes dislodged from the cell contact system due to a strong vibration and, over a short distance, causes this short circuit by connecting the positive terminal to a cell cup designed as the negative terminal of the battery cell.

[0009] A thermal trip of the fuse element represents an alternative fault scenario. In this case, the fuse element melts due to heat escaping directly from the cell during a thermal runaway or medium-resistance short circuit with resulting moderate external currents. This cell-internal fault heats up a cell terminal to which the fuse element is electrically and thermally connected.

[0010] In a typical battery pack or module, the entire cell contacting system is designed as a stamped and bent metal component and is surrounded by a protective and mechanically supporting structure made of plastic or another electrical insulating material. Increasing packing density, as well as ever more powerful elementary storage cells in battery systems with rising capacity, necessitate progressively more effective cooling of all areas within a battery module or pack. This also cools the cell contacting system and the fuse elements connected to or contained within it, which are designed as thermal fuses. Due to the cooling effect, the tripping function of a fuse element can no longer be reliably guaranteed, i.e.,...that a tripping point or even the entire tripping characteristic of the safety element shifts out of a predetermined range and can therefore even be undefined. Here, a safety element, which according to the invention is also well thermally insulated from its environment as part of a cell contacting system, provides effective relief. According to the invention, the cell connector is optimally designed for the current-carrying capacity and heat dissipation of the battery cell, so that even more intensive cooling cannot affect the tripping characteristic of the safety element. The safety characteristic of the safety element can therefore be designed independently of cooling, according to an application and hazard scenario.

[0011] Advantageous further developments are the subject of the respective dependent claims. Accordingly, the locking element on the cell contacting system is enclosed by a space or area filled with air or at least another gas. This solution represents a good and cost-effective solution for thermal insulation of the locking element from a cooled, immediately adjacent environment.

[0012] In a preferred embodiment of the invention, the locking element is surrounded by a coating that is resistant to a coolant. For this purpose, in a further development, the coating is made entirely or partially of plastic, a porous material such as ceramic, an unfired or green ceramic material, which, for example, is preferably designed as a paste-like mass that can be applied via a pipette or printed, or consists of a laminate made of fiber-reinforced plastics.

[0013] In a particularly advantageous embodiment of the invention, the covering made of plastic, a porous mass, or a laminate of fiber composite material is additionally supplemented with fiber components in the form of individual fibers or fabrics made of thermally stable fibers such as glass, ceramic, silicate, or aramid fibers. This increases the thermal stability and insulating capacity of the covering.

[0014] In a preferred embodiment of the invention, the area around the locking element comprises a half-shell made of an electrically insulating material.

[0015] Advantageously, the area around the locking element, in particular designed as a half-shell, is part of an insulating or plastic carrier of the cell contacting system.

[0016] Preferably, the half-shell surrounding the locking element is filled with a pasty or potting compound in a recess. It is preferred that the half-shell, which in particular has a recess, is integrally connected to the plastic support.

[0017] In a further development of the invention, the space around the locking element is formed by two half-shells made of an electrically insulating and thus also thermally insulating material. These half-shells are preferably formed integrally with an upper and a lower part of an insulating support or several support parts, between which an electrically conductive part of the cell contacting system with the locking element is preferably fixed. 03850PWÖ

[0018] Preferably, one of the half-shells has an opening for filling with a potting compound. This feature enables a reliable and simple application of the potting compound described above. When selecting a material surrounding a respective safety element as an insert and / or potting compound, its ability to prevent the reactivation of a tripped fuse, the escape of particles from the area of ​​the safety element, and the extinguishing of any arc that may form in the area of ​​the safety element are also essential considerations.

[0019] In one embodiment of the invention, the locking element is in contact with an insert and fixed between the parts of the cell contacting system carrier. In this embodiment, the insert is a thin layer with a thickness of 0.1 mm to 0.5 mm. The insert preferably consists of ceramic paper, ceramic fiber mats, ceramic fiber fabrics, or glass fiber mats or fabrics, mica, silicone, or a fiber-reinforced plastic composite, so-called sheet molding compound made of ceramic or glass fibers. Ideally, the insert is oil-resistant and designed for immersion cooling.

[0020] Preferably, a module and / or pack is characterized in that the cell contacting system comprises a plastic carrier that is uniform for all variants of the pack and / or module and a grid-like stamped-bent part adapted to a respective specification of the electrical properties with insulations for connecting the elementary cells in the form of a specific series and parallel connection, which has two poles, wherein the cell contacting system has one or more of the previously described technical features.

[0021] The thermal insulation, in the form of the selective encapsulation of fuse elements within a cell contacting system described above with various implementation methods, protects against environmental influences without hindering optimal cooling of the cell contacting system itself. At the same time, this approach results in minimal electrical resistance of the fuse elements while reliably disconnecting even a single cell in the event of an overload caused by excessive current, the occurrence of which is defined as a fault condition when a predetermined threshold is exceeded. Thus, the encapsulation of the fuse element reduces any inherent heat loss, thereby increasing the overall efficiency of the battery system.

[0022] In summary, good thermal insulation, achieved through selective encapsulation of the fuse element from its environment as described above, allows for precise adjustment of its electrical tripping characteristics and the use of fuse elements with a lower intrinsic resistance compared to the state of the art. This is because, without significant heat dissipation, even a lower resistance is sufficient for the reliable tripping and interruption of an electrical connection within the fuse element once a certain threshold current flow is exceeded. The adjacent cell contacting system and the elementary storage cells can be cooled independently, including through the use of immersion cooling.The above-described design significantly increases the operational reliability of the battery system, while simultaneously reducing the operating resistance of each electrical safety element, which further contributes to an increase in the electrical efficiency of the battery system.

[0023] Further features and advantages of embodiments of the invention are explained in more detail below with reference to exemplary embodiments and the drawing. The drawing schematically shows:

[0024] Figures 1a to 1c: a section of a perspective top view of an exemplary cell contacting system with a section of a top view and a side view;

[0025] Figures 2a and 2b: a top view and a side view of a section of another exemplary embodiment of a cell contacting system;

[0026] Figures 3a and 3b:

[0027] Illustrations of a further exemplary embodiment of a cell contacting system analogous to Figures 2a and 2b;

[0028] Figures 4a and 4b: a top view of a section of a known cell contacting system with bond connections at both cell poles of each elementary memory cell with an alternative implementation form in a detailed representation and

[0029] Figure 5: a top view of a section of a known 03850PWQ part designed as a stamped and bent part.

[0030] Cell contacting system with connecting pieces designed as locking elements.

[0031] Across the various illustrations of the drawing, the same reference symbols are always used for identical elements or process steps. Without limiting the invention, a flat housing as a cuboid body for a module and / or pack of a high-voltage battery system constructed therefrom is presented and described below, in which, due to the high number and density of the electrical connections, elementary cells of a cylindrical design are considered. However, it is obvious to those skilled in the art that adaptations to other spatial shapes are also possible, moving away from flat housings, e.g., to a polygonal or even curved housing, in order to improve the utilization of available installation space. The battery module is designed for storing electrical energy from any source, such as...Designed for use with an external charging station or a generator-driven electric drive motor, as well as for supplying stored electrical energy to power, among other things, the drive motor and auxiliary and assistance systems. Furthermore, adaptations to applications outside of terrestrial vehicles are easily possible, particularly for stationary storage devices. Transfer to a cell contacting system for prismatic and pouch storage cells is also possible without further graphical representation.

[0032] In high-voltage battery storage systems, many individual cells are connected in modules and / or packs to form a larger system via series and / or parallel connections. If a single cell fails, for example, due to an internal short circuit, this leads to very large fault currents, which can cause thermal runaway of the affected cell and thus quickly and inevitably result in the thermal destruction of the entire battery system. To prevent such destruction caused by a single cell in the event of a fault, a fuse is typically installed on each cell. In the event of an overload, this fuse irreversibly disconnects the affected cell from the overall system. For the fuse to trip reliably, it must represent a bottleneck in the current path.However, this generally leads to increased power loss during operation and thus reduces the efficiency of the entire battery system.

[0033] Figure 4a shows a top view of a section of a known cell contacting system 1, which is designed as a grid-like stamped and bent metal sheet component for providing desired electrical output parameters at terminals (not shown) of a battery module or pack by means of a predetermined electrical interconnection of elementary storage cells 2 in series and / or parallel circuits. In this cell contacting system 1, each electrical contact of essentially strip-shaped sheet metal parts 3 to one of the poles P, N of an elementary storage cell 2 of cylindrical format is made by bond connections 4. Each bond connection 4 is designed as a metallic wire bridge, and its dimensions, and in particular its free cross-section, act as an electrical locking element 5.

[0034] Figure 4b shows a top view of an alternative embodiment of the bond connections 4 of Figure 4a in a detailed view. Here, the locking element 5 is designed as a defined constriction between two connection surfaces 6 of a bond connection 4. Figure 5 shows a top view of a section of a known cell contacting system 1, which is designed as a stamped and bent part. Here, connecting pieces of the essentially strip-shaped sheet metal part 3 are provided as locking elements 5 to the connection surfaces 6. The respective connection surfaces 6 are connected by laser welding to poles P, N of the elementary storage cells 2 of a cylindrical format. A locking element 5 is characterized by defined incisions through which constrictions with a significantly increased current density are formed.As in the known implementation forms described above, the narrow passages are used to define a triggering characteristic of a respective safety element 5.

[0035] Under normal circumstances, fuse elements 5 of the type mentioned above exhibit an electro-thermal tripping with melting of the fuse element 5 due to a low-resistance short circuit in the battery system, e.g., between the positive and negative terminals of an elementary storage cell 2. Alternatively, a thermal tripping occurs, in which the fuse element 5 melts due to heat directly from the storage cell in question during thermal runaway, or a medium-resistance short circuit with resulting moderate currents that overheats the cell terminals of the storage cell in question.

[0036] In high-performance battery systems, the entire battery system is cooled, for example, by an electrically non-conductive coolant. The cell contact system, around which the coolant flows, contributes significantly to the cooling performance of the overall system. However, the cooling effect of the coolant can compromise the reliable function of the fuse element 5. The dissipation of electrical heat loss from the vicinity of the fuse element 5 delays its tripping (03850PWÖ). As a result, the fuse element 5 only trips at significantly higher temperatures. In other words, the tripping characteristic of the fuse element 5 is shifted by the coolant in a largely unpredictable manner. Therefore, despite direct cooling by air or oil, etc., the high-performance battery system faces the additional risk of further overheating of a faulty cell.

[0037] Figure 1a shows a section of a perspective top view of an exemplary embodiment with a section of a cell contacting system 1, in which the effectiveness of the individual cell protection by means of fusible links or locking elements 5 is ensured by good thermal insulation against an actively cooled environment. For this purpose, a cell contacting system 1, e.g. according to Figure 5, is formed as a stamped and bent part from a metal sheet with meandering locking elements 5 integrally formed from a substantially strip-shaped sheet metal part 3 towards the connection surfaces 6, in which a region 7 around each locking element 5 is then additionally overmolded or cast with a hardening liquid.The material used for this purpose is, in exemplary embodiments, a porous mass of plastic, a two-component epoxy resin, a fast-curing or UV-curing lacquer, a powder coating, or a pasty, unfired coating of a ceramic material. Curing of this, typically in a pasty form, by screen printing or metered spraying onto the substrate, completes the formation of a mechanically resilient and thermally insulating encapsulation of the fuse elements 5. Finally, the cell contacting system 1 is mounted in or on a carrier 8 made of an electrically insulating and temperature-resistant plastic in the usual manner, and the cell contacting system 1 is then connected via the connection surfaces 6 to the respective poles P, N of the elementary memory cells 2.

[0038] The top and side views of this cell contacting system 1 in Figures 1b and 1c show the advantage of this embodiment with a form-fitting area 7 that is thermally insulating and electrically insulating against its surroundings. Due to its porosity, this area 7 is filled with air or at least with another gas.

[0039] Figures 2a and 2b show a top view and a side view of a further embodiment of a cell contacting system 1, in which, following the above-described production of a one-piece stamped-bent part from a metal sheet, it is mounted in a carrier 8 made of plastic. This carrier now has a bordered recess 9 in the area of ​​the respective locking element 5, forming a pocket or basin into which a liquid or pasty potting compound 10 is subsequently introduced and then cured. The potting compound 10 completely encloses the locking element 5. For the potting compound 10, a material from the group consisting of plastic, two-component epoxy resin, a fast-curing or UV-curing lacquer, a powder coating, and a coating with a green or unsintered ceramic, particularly in the form of a paste, is preferred.After hardening, a thermally insulating encapsulation is formed again around each of the locking elements 5 with high process reliability.

[0040] The side view of Figure 2b shows a continued compact structure of the cell contacting system 1 also around the locking element 5 .

[0041] In an exemplary embodiment not further illustrated, the recess 9 is not a single-piece part of the support 8, which here consists of a plastic, but is a separate 03850PWÖ.

[0042] Half-shell 9 is formed. In this example as well, a recess around the respective securing element 5 is filled with a casting compound 10.

[0043] Figures 3a and 3b show illustrations of a further embodiment of a cell contacting system 1 analogous to Figures 2a and 2b, in which two half-shells 9, 11 are provided, which enclose and fix the respective safety element 5 and are filled with air or at least another gas or one of the potting compounds 10 specified above to set an electrical tripping characteristic in the area 7. For this purpose, one of the half-shells 9, 11 has an opening 12 through which the potting compound 10 is poured between the half-shells 9, 11, which are fixed to each other at their edges. Both half-shells 9, 11 can, for example, be made of a plastic, be integrally connected to each other via a foil hinge, and be designed to automatically close around the safety element 5 by means of a snap-fit ​​connection. The potting compound 10 can protect the locking element against immersion cooling, e.g.Seal with an oil as a cooling fluid. However, since the potting compound 10 essentially serves as thermal insulation against the environment and thus also against immersion cooling, the cooling fluid can also penetrate into an area 7 around the safety element 5, as long as good thermal insulation is maintained, e.g. by only minimal exchange of cooling fluid, to maintain the predetermined electrical tripping characteristic.

[0044] The exemplary embodiment described above is advantageously realized by forming the half-shells 9, 11 integrally on an upper and a lower part of an insulating carrier 8 of the cell contacting system 1, enclosing the locking element 5. According to 03850PWÖ

[0045] During assembly of the carrier 8 of the cell contacting system 1, each space 7 is then filled with a potting compound 10 via an opening 12, which can also be used to fix the parts of the insulating carrier 8 of the cell contacting system 1.

[0046] Alternatively, the locking element 5 is fixed between the parts of the carrier 8 of the cell contacting system 1 or half-shells 9, 11 and is in contact with an insert 13. The insert 13 can be, among other things, a ceramic paper and, in one embodiment, impregnated with a porous mass or potting compound 10.

[0047] Reference symbol list

[0048] Cell contact system, elementary storage cell of a cylindrical format, strip-shaped sheet metal part of the cell contact system, 1 bond connection, electrical safety element

[0049] Connection surface of a connector

[0050] Area around a safety element 5

[0051] Carrier, in particular consisting of a thermally resistant and electrically insulating plastic; Recess / half-shell 0; pasty mass / casting compound 1; second half-shell / recess, mirror-symmetrical to 9; 2 Opening for filling the space 7 with casting compound; 10; 3 Insert; 4 Grid-like stamped-bent part

[0052] N Minus pole / negative pole of the elementary memory cell 2

[0053] P Plus pole / positive pole of the elementary memory cell 2

Claims

Claims 1. Cell contacting system by which elementary storage cells are electrically interconnected in series and / or parallel circuits to form a battery module and / or pack and in which at least one electrical contact to a pole of an elementary storage cell is designed as an electrical safety element, characterized in that the safety element (5) is thermally well insulated from an environment.

2. Cell contacting system according to the preceding claim, characterized in that the locking element (5) on the cell contacting system (1) is enclosed in a region (7) which is filled with air or at least with another gas.

3. Cell contacting system according to the preceding claim, characterized in that the locking element (5) is enclosed by a coating (10) that is resistant to a coolant and is made entirely or partially of plastic, a porous mass, in particular in the form of an unfired or green ceramic material, or a laminate of fiber-reinforced plastic composites.

4. Cell contacting system according to the preceding claim, characterized in that the covering comprises a fiber component in the form of individual fibers or fabrics made of thermally stable fibers such as glass, ceramic, silicate or armid fibers.

5. Cell contacting system according to one of the preceding claims, characterized in that the area (7) around the locking element (5) comprises a half-shell (9) made of an electrically insulating material.

6. Cell contacting system according to one of the preceding claims, characterized in that the area (7) around the locking element (5) is part of an insulating or plastic carrier (8) of the cell contacting system (1).

7. Cell contacting system according to one of the two preceding claims, characterized in that the half-shell (9) is filled with a potting compound (10) around the locking element (5).

8. Cell contacting system according to one of the three preceding claims, characterized in that the half-shell (9) is integrally connected to the plastic carrier (8).

9. Cell contacting system according to one of the four preceding claims, characterized in that two half-shells (9, 11) are provided made of an electrically insulating material.

10. Cell contacting system according to one of the five preceding claims, characterized in that the two half-shells (9, 11) are formed integrally on an upper and a lower part of an insulating carrier (8) enclosing the locking element (5).

11. Cell contacting system according to one of the preceding claims, characterized in that at one of the 03850PWÖ The half-shells (9, 11) have an opening (12) for filling with a casting compound (10).

12. Cell contacting system according to the preceding claim, characterized in that the locking element (5) is fixed in contact with an insert (13) between the parts of the carrier (8) of the cell contacting system (1).

13. Module and / or pack, characterized in that the cell contacting system (4) comprises a uniform plastic carrier (8) for all variants of the pack and / or module (1) and a grid-like stamped and bent part (14) adapted to a specific requirement of the electrical properties with insulation for connecting the elementary cells (2) in the form of a specific series and parallel connection, which has two poles, wherein the cell contacting system is designed according to one of the preceding claims.

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