Rechargeable battery pack

Abstract

Rechargeable battery pack having a rechargeable battery cell carrier and a cylindrical rechargeable battery cell which is inserted into the rechargeable battery cell carrier in the axial direction, the rechargeable battery cell having a central positive pole which is electrically contacted by means of a cell connector, and the rechargeable battery pack having a sealing element in order to protect the rechargeable battery cell from moisture, the sealing element annularly surrounding the central positive pole and preferably being spaced apart therefrom on all sides.

Description

[0001] Battery pack

[0002] The present invention relates to a battery pack comprising a battery cell carrier and a cylindrical battery cell inserted axially into the battery cell carrier, wherein the battery cell has a central positive terminal which is electrically contacted by means of a cell connector. The battery pack includes a sealing element to protect the battery cell against moisture. Such battery packs are generally known from the prior art and are used, for example, in the power supply of electric power tools.

[0003] DE 10 2018 210 663 A1 discloses a battery pack for a hand-held power tool, comprising a housing that includes a cell housing in which at least one battery cell is received via an axial opening, wherein the cell housing has at least one radial opening through which the at least one battery cell can be contacted. A sealing element is arranged in the region of the radial opening, sealing the radial opening.

[0004] WO 2022 / 073622 A1 describes a battery pack housing for accommodating at least one battery, comprising an inner housing that defines a receiving space for the at least one battery, and an outer housing that at least partially surrounds the inner housing. A degassing opening is formed on the inner housing, which fluidly connects the receiving space to the surrounding environment of the battery pack housing. The degassing opening is closed by the outer housing, and a safety pressure relief valve is arranged in the area of ​​the degassing opening.

[0005] DE 20 2016 006 515 U1 discloses a battery block comprising a plurality of battery cells and a common housing for the battery cells, consisting of at least a first housing part and a second housing part. Sealing elements are arranged on the second housing part, engaging in a gap between the cell bodies and in a gap between the cell bodies and the housing.

[0006] The object of the present invention is to provide a battery pack that is easy to manufacture and safe.

[0007] The problem is solved by having the sealing element surround the central positive terminal of the battery cell in a ring-like fashion and preferably be spaced away from it on all sides. The sealing element can be designed such that it rests on the shoulder of the positive terminal or that the sealing element rests on the shoulder of the positive terminal.

[0008] The invention incorporates the finding that the central positive terminal of a battery cell is particularly vulnerable to penetrating moisture or water, since the potential difference between the negative terminal (negative terminal) and the positive terminal (positive terminal) is typically very close. Electrolyte ingress can lead to electrochemical corrosion, which eventually damages the battery pack. In addition to damage to the battery cell, this can also pose risks to the user. These disadvantages are avoided by the sealing element designed according to the invention. In particular, it was recognized that two aspects are of critical relevance. Firstly, the unrestricted functionality of a preferably included venting mechanism with a vent opening, which allows the battery cell to outgas in the event of a fault, and secondly, the provision of a sufficiently large surface area of ​​the central positive terminal for connection to the cell connector.Because the sealing element according to the invention surrounds the central positive pole of the battery cell in a ring shape and is preferably spaced away from it on all sides, optimal cell contacting, for example by means of laser welding processes, is made possible.

[0009] In a particularly preferred embodiment, a vent opening covered by the sealing element is formed in the cell connector, wherein the sealing element and the vent opening define a pressure relief valve. This facilitates the opening of the vent opening by gas pressure and / or by temperature exposure of the sealing element. Alternatively or additionally, the sealing element can be made of a material with a melting or decomposition temperature that is lower than the temperature of the escaping gas. In a particularly preferred embodiment, the melting temperature or the point of thermal decomposition of the sealing element is less than 150 degrees Celsius, and more preferably less than 125 degrees Celsius. It has proven advantageous if the sealing element is made of an elastomer, in particular a thermoplastic elastomer.The material of the sealing element is chosen such that escaping gas from a cell can at least partially melt the material of the sealing element. The molten sealing element then allows any overpressure generated by the escaping gas to be relieved.

[0010] The sealing element may have a ring-shaped embossing that promotes deflection of the sealing element.

[0011] In a further preferred embodiment, the sealing element has an axially projecting rim that closes or surrounds the vent opening. The rim can be deflected by gas escaping from the battery cell when a minimum pressure is exceeded, particularly in a radial direction. It has proven advantageous to have several vent openings in the cell connector, each of which is covered by the sealing element. In a further preferred embodiment, the inner diameter of the sealing element is smaller than the outer diameter of the battery cell. It has proven advantageous for the sealing element to project axially beyond the central positive terminal.

[0012] In a further preferred embodiment, the battery cell carrier has a support rib that surrounds the battery cell in a ring-like manner. The sealing element can be supported axially on the support rib. In a particularly preferred embodiment, the battery cell has a cell cup, wherein the sealing element is supported axially on the cell cup. It has also proven advantageous if the sealing element covers a transition between the support rib and the cell cup. In a further preferred embodiment, the negative terminal of the battery cell is provided by the cell cup of the battery cell. It has proven advantageous if the space between the sealing element and the central positive terminal is free of potting compound. In a further preferred embodiment, the cell connector is metallic and welded to the central positive terminal in a welded area.

[0013] In a particularly preferred embodiment, the battery pack comprises a plurality of battery cells and a plurality of sealing elements, wherein the plurality of sealing elements are realized by providing a plurality of circular openings in a sealing mat. Each of the circular openings can surround a respective central positive terminal of a battery cell of the plurality of battery cells in a ring-like manner, preferably spaced apart on all sides. It has proven advantageous if each of the circular openings surrounds a respective central positive terminal of a battery cell of the plurality of battery cells in a ring-like manner, preferably spaced apart on all sides. In the case of an antiparallel arrangement of the battery cells in the battery cell carrier, even a partial one, it is not necessarily required that each of the circular openings surround a respective central positive terminal of a battery cell of the plurality of battery cells in a ring-like manner. Rather, for example, a negative terminal of a battery cell can be arranged "behind" every second circular opening.In the case of an antiparallel arrangement of the battery cells in the battery cell carrier, a sealing mat can also be provided on both sides of the battery cells, so that as a result each of the central positive poles benefits from a sealing element arranged according to the invention.

[0014] In a further preferred embodiment, a predominant area of ​​the sealing mat lies in a common plane with the majority of central positive terminals. In a particularly preferred embodiment, exactly one cylindrical battery cell, preferably of type 21700, is accommodated in each cylindrical chamber. It has proven advantageous if each of the cylindrical battery cells is directly surrounded (apart from any air inclusions) by the inner surface of the cylindrical chamber. In particular, it is provided that no elastomeric components or the like are present between the cylindrical battery cell and the inner surface.

[0015] Further advantages will become apparent from the following description of the figures. The figures illustrate a particularly preferred embodiment of the present invention. The figures, the description, and the claims contain numerous features in combination. It will be advantageous for those skilled in the art to also consider the features individually and combine them into meaningful further combinations.

[0016] In the figure, identical and similar components are numbered with the same reference symbols.

[0017] It shows:

[0018] Figure 1 shows a first embodiment of a battery pack in sectional view; and

[0019] Figure 2 shows the battery pack of Figure 1 in a perspective exploded view.

[0020] Example implementation:

[0021] A first preferred embodiment of a battery pack 100 in sectional view is shown in Figure 1. The battery pack 100 comprises a battery cell carrier 10 and a cylindrical battery cell 1 inserted axially AR into the battery cell carrier 10.

[0022] Battery cell 1 has a central positive terminal 3, which is electrically contacted by means of a cell connector 20. The cell connector 20 is metallic and welded to the central positive terminal 3 in a weld area SB. The battery pack 100 also includes a sealing element 30, which protects the battery cell 1 against moisture or dirt (= dust).

[0023] The sealing element 30 surrounds the central positive terminal 3 in a ring shape (see Figure 2 regarding the ring-shaped design). The sealing element 30 is spaced away from the central positive terminal 3 on all sides.

[0024] In other words, the sealing element 30 is not in direct contact with the central positive terminal 3. Therefore, optimal cell contacting could be achieved, exemplified here by laser welding in welding area SB. The inner diameter ID of the sealing element 30 is smaller than the outer diameter AD of the battery cell 1.

[0025] In the cell connector 20, a vent opening 25 is formed, covered by the sealing element 30, wherein the sealing element 30 and the vent opening 25 define a pressure relief valve. The sealing element 30 has a flange 31 projecting in the axial direction AR, which closes the vent opening 25. The flange 31 can be deflected by gas escaping from the battery cell when a minimum pressure is exceeded, particularly in the radial direction RR outwards. For this purpose, the sealing element 30 is made of an elastomer that has a higher elasticity than the cell connector 20.

[0026] The sealing element 30 projects beyond the central positive terminal in the axial direction AR. The flange 31 preferably also projects beyond the axial direction AR. The sealing element 30 and the central positive terminal 3 lie in a common plane EG.

[0027] The battery cell carrier 10 also has a support web 11 that surrounds the battery cell 1 in a ring-like manner. As can be seen in Fig. 1, the sealing element 30 is supported axially AR on the support web 11. The battery cell 1 also has a cell cup 5, with the sealing element 30 also supported axially AR on the cell cup 5. The sealing element 30 covers a transition UG between the support web 11 and the cell cup 5. A negative terminal of the battery cell 1 is provided by the cell cup 5 of the battery cell 1. A space AR between the sealing element 30 and the central positive terminal 3 is free of potting compound or the like. Fig. 2 shows the battery pack of Fig. 1 in a perspective exploded view; that is, for illustrative purposes, the cell connector 30 is not yet welded. The battery pack 100 has a plurality of battery cells 1 , 1', 1".

[0028] It is readily apparent that the cell connector 20 has several vent openings 25, 25', 25" formed, each of which is covered by the sealing element 30. In the embodiment shown here, eight vent openings are provided per battery cell in an annular arrangement.

[0029] Furthermore, the battery pack 100 has a plurality of sealing elements 30, 30', 30"", wherein the plurality of sealing elements 30, 30', 30" are realized by providing a plurality of circular openings 33, 33', 33" in a sealing mat 35. Each of the circular openings 33, 33', 33" surrounds a respective central positive terminal 3, 3', 3" of a battery cell of the plurality of battery cells 1, 1', 1" in a ring-like manner and is spaced apart on all sides. A predominant area of ​​the sealing mat 35 lies in a common plane EG with the plurality of central positive terminals positive terminal 3, 3', 3" (see Figure 1, positive terminal 3 as an example). A ring-shaped embossing 37 is clearly visible, which facilitates deflection of the sealing element 30 in the event of gas overpressure.

[0030] List of reference signs

[0031] 1 battery cell

[0032] 3 central positive terminal

[0033] 5 cell cups

[0034] 10 battery cell carriers

[0035] 11 Support bridge

[0036] 20 cell connectors

[0037] 25, 25' 25" exhaust opening

[0038] 30 sealing element

[0039] 31 Brim

[0040] 33 33' 33" circular openings

[0041] 35 sealing mat

[0042] 100 battery pack

[0043] AD outer diameter

[0044] AR axial direction

[0045] EC common level

[0046] ID inner diameter

[0047] RR radial direction

[0048] SB welding area

[0049] UG transition

Claims

Patent claims 1. Battery pack (100) with a battery cell carrier (10) and a cylindrical battery cell (1) inserted into the battery cell carrier (10) in an axial direction (AR), wherein the battery cell (1) has a central positive terminal (3) which is electrically contacted by means of a cell connector (20), and wherein the battery pack (100) has a sealing element (30) to protect the battery cell (1) against moisture, characterized in that the sealing element (30) surrounds the central positive terminal (3) in a ring shape and is preferably spaced away from it on all sides.

2. Battery pack (100) according to claim 1 , characterized in that a blow-out opening (25) covered by the sealing element (30) is formed in the cell connector (20), wherein the sealing element (30) and the blow-out opening (25) define a pressure relief valve.

3. Battery pack (100) according to claim 2, characterized in that the sealing element (30) has a rim (31) projecting in the axial direction (AR) which closes or surrounds the blow-out opening (25).

4. Battery pack (100) according to claim 2 or 3, characterized in that several vent openings (25, 25', 25") are formed in the cell connector (20), wherein each of the vent openings (25, 25', 25") is covered by the sealing element (30).

5. Battery pack (100) according to one of the preceding claims, characterized in that an inner diameter (ID) of the sealing element (30) is smaller than an outer diameter (AD) of the battery cell (1).

6. Battery pack (100) according to one of the preceding claims, characterized in that the sealing element (30) projects beyond the central positive pole in axial direction (AR).

7. Battery pack (100) according to one of the preceding claims, characterized in that the battery cell carrier (10) has a support web (11) surrounding the battery cell (1) in a ring shape, wherein the sealing element (30) is supported in the axial direction (AR) on the support web (11).

8. Battery pack (100) according to one of the preceding claims, characterized in that the battery cell (1) has a cell cup (5), wherein the sealing element (30) is supported in the axial direction (AR) on the cell cup (5).

9. Battery pack (100) according to claims 7 and 8, characterized in that the sealing element (30) covers a transition (UG) between support web (11) and cell cup (5).

10. Battery pack (100) according to claim 8 or 9, characterized in that a negative terminal of the battery cell (1) is provided by the cell cup (5) of the battery cell (1).

11. Battery pack (100) according to one of the preceding claims, characterized in that a space (AR) between the sealing element (30) and the central positive terminal (3) is free of a potting compound.

12. Battery pack (100) according to one of the preceding claims, characterized in that the cell connector (20) is metallic and is welded onto the central positive pole (3) in a welding area (SB).

13. Battery pack (100) according to one of the preceding claims, characterized in that the sealing element (30) consists of an elastomer, in particular a thermoplastic elastomer.

14. Battery pack (100) according to one of the preceding claims, characterized in that the battery pack (100) comprises a plurality of battery cells (1, T, 1") and a plurality of sealing elements (30, 30', 30"), wherein the plurality of sealing elements (30, 30', 30") are provided by a plurality of circular openings. (33, 33', 33") are realized in a sealing mat (35), wherein preferably each, but at least a part of the circular openings (33, 33', 33") surrounds a respective central positive terminal (3, 3', 3") of a battery cell of the plurality of battery cells (1, 1', 1") in a ring-shaped manner and spaced apart on all sides.

15. Battery pack (100) according to claim 13, characterized in that a predominant area of ​​the sealing mat (35) lies in a common plane (EG) with the plurality of central positive terminals (3, 3', 3").

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