ELECTROCHEMICAL ENERGY STORAGE CELL

Abstract

An electrochemical energy storage cell comprising a cell winding received in a casing, wherein the casing is closed at least on one end face by a cover, wherein the cover has a fixing portion for fixing the cover on the casing and a pole portion for contacting a conductor of the cell winding, wherein the fixing portion and the pole portion are connected to one another via a compensating element, wherein the compensating element is formed to be elastic and electrically insulating.

Claims

1. An electrochemical energy storage cell, comprising a cell winding which is received in a casing, wherein the casing is closed at least on one end face by a cover, wherein the cover has a fixing portion for fixing the cover to the casing and a pole portion for contacting a conductor of the cell winding, wherein the fixing portion and the pole portion are connected to one another via a compensating element, wherein the compensating element is formed to be elastic and electrically insulating.

2. The energy storage cell according to claim 1, wherein the compensating element is made of elastomeric material.

3. The energy storage cell according to claim 1, wherein the compensating element is elastically movably shaped.

4. The energy storage cell according to claim 1, wherein a predetermined breaking point is introduced into the compensating element.

5. The energy storage cell according to claim 4, wherein the predetermined breaking point (10) is in the form of a groove.

6. The energy storage cell according to claim 1, wherein the cover is connected to the casing in a materially-bonded manner.

7. The energy storage cell according to claim 1, wherein the cover is fastened to the casing by means of electromagnetic pulse forming.

8. The energy storage cell according to claim 1, wherein an insulation element is arranged between the cell winding and the cover.

9. The energy storage cell according to claim 8, wherein the insulation element is formed of an elastomeric material.

10. The energy storage cell according to claim 8, wherein the insulation element is formed of a silicone material.

11. The energy storage cell according to claim 8, wherein the insulation element is equipped with thermally conductive particles.

12. The energy storage cell according to claim 8, wherein a further insulation element is arranged between the bottom of the casing and the cell winding.

Description

[0022] Some embodiments of the energy storage cell according to the invention are explained in more detail below with reference to the figures. These show, in each case schematically:

[0023] FIG. 1 a profile view of the upper portion of an energy storage cell;

[0024] FIG. 2 the cover of an energy storage cell;

[0025] FIG. 3 the cover with conductor;

[0026] FIG. 4 the cover with predetermined breaking points;

[0027] FIG. 5 the cover in the damaged state;

[0028] FIG. 6 the cover with the predetermined breaking point broken;

[0029] FIG. 7 an energy storage cell with an insulation element;

[0030] FIG. 8 an energy storage cell with an insulation element in the bottom and in the cover;

[0031] FIG. 9 a compensating element with elastic shaping.

[0032] The figures show an electrochemical energy storage cell 1 in the form of a round cell. The energy storage cell 1 comprises a cell winding 2 which is accommodated in a casing 3. If the energy storage cell 1 is in the form of a lithium-ion battery, the cell winding 2 comprises two conductors and two separators, wherein the conductors are separated from each other by the separators. An active material is applied to the conductors and the two conductors separated by the separators are wound into a round structure. The casing 3 is made of metallic material and is cylindrical in shape. On one end face, the casing 3 has a bottom 13 formed of the same material and integral with the cylindrical wall 15. On one end face 4, the casing 3 is closed by a cover 5.

[0033] The cover 5 has a fixing portion 6 for fixing the cover 5 to the casing 3. Furthermore, the cover 5 has a pole portion 7 for contacting a conductor 8 of the cell winding 2. The second conductor of the cell winding 2 is associated with the bottom 13 of the casing 3.

[0034] The fixing portion 6 and the pole portion 7 are connected to each other via a compensating element 9. The compensating element 9 is elastic and electrically insulating. In this case, the compensating element 9 is made of elastomeric material.

[0035] When viewed from above, the cover 5 is circular in shape. The pole portion 7 is centred and centrally located in the cover 5 and surrounded by the compensating element 9. The compensating element 9 is positively and materially connected to the pole portion 7. The fixing portion 6 has a disc-shaped portion in whose opening the compensating element 9 and the pole portion 7 are arranged. The compensating element 9 is fixed in a materially-bonded manner in the area of the edge of the opening of the fixing portion 6. The fixing portion 6 further comprises a cylindrical portion which rests on the edge of the end face side of casing 3. In the area of the two contacting edges, the cover 5 and the casing 3 are joined together by means of electromagnetic pulse forming in a materially-bonded manner.

[0036] FIG. 1 shows the upper portion of an electrochemical energy storage cell 1 in the form of a round cell. The conductor 8 is centrally connected in the cell winding 2 to an electrode of the cell winding 2. The compensating element 9 is disc-shaped and elastic because it is made of elastomeric material. This allows the pole portion 7 to move in the axial direction depending on the internal pressure of the casing 3. The compensating element 9 forms an electrical insulation between the pole portion 7 and the fixing portion 6. In this respect, the casing 3 together with the fixing portion 6 can form a second pole.

[0037] FIG. 2 shows the cover shown in FIG. 1 in detail.

[0038] FIG. 3 shows the cover shown in FIG. 1 in detail together with the conductor 8, which is electrically conductively attached to the pole portion 7.

[0039] FIG. 4 shows another embodiment of the cover shown in FIG. 1. In the present embodiment, the compensating element 9 is provided with a predetermined breaking point 10. FIG. 4 shows two different configurations of the predetermined breaking point 10. In the embodiment to the right of the line of symmetry, the predetermined breaking point 10 is introduced externally into the compensating element 9. In the embodiment to the left of the line of symmetry, the predetermined breaking point 10 is introduced on the side of the compensating element 9 facing the cell winding 2. In both embodiments, the predetermined breaking point 10 is in the form of a V-shaped groove which surrounds the pole portion 7 concentrically.

[0040] FIG. 5 shows the cover 5 shown in FIG. 4, with the pole portion 7 spaced axially from the cell winding 2 due to increased internal pressure inside the casing 3. In this case, the conductor 8 is torn into two portions 8′, 8″ so that the pole portion 7 is electrically insulated from the cell winding 7. In this respect, the energy storage cell 1 is de-energized in this embodiment. This can prevent further charging of the energy storage cell 1, which would be particularly harmful after the pressure increase inside the energy storage cell 1. In the embodiment shown in FIG. 5, only a deformation of the compensating element 9 has taken place. The predetermined breaking points 10 are still intact.

[0041] In the embodiment according to FIG. 6, the internal pressure inside the casing 3 has increased once again compared to the embodiment shown in FIG. 5. In this case, the permissible internal pressure has exceeded a predetermined level and the predetermined breaking point 10 has opened. This allows gas to escape from the interior of the casing 3, so that the pressure inside is reduced in a targeted and controlled manner. In this respect, by opening the predetermined breaking point 10, a targeted destruction of the energy storage cell 1 takes place and an explosive destruction of the energy storage cell 1 can be prevented.

[0042] FIG. 7 shows an energy storage cell 1 according to FIG. 1, wherein an insulation element 11 is arranged between the cell winding 2 and the cover 5. The insulation element 11 is made of elastomeric material, in this case a silicone material. The insulation element 11 is provided with thermally conductive particles 12. After assembly, the insulation element 11 comes into contact with the electrolyte of the cell winding 2, causing the insulation element 11 to swell. As a result, the insulation element 11 fills the space between the cell winding 2 and the cover 5. The thermally conductive particles are electrically non-conductive mineral particles. Advantageous thermally conductive particles 12 include aluminium oxide (Al.sub.2O.sub.3), aluminium oxide hydroxide (AlOOH), aluminium hydroxide (Al(OH).sub.3), magnesium hydroxide (Mg(OH).sub.2), or boron nitride (BN).

[0043] FIG. 8 shows a further development of the energy storage cell 1 shown in FIG. 7. In the present embodiment, a further insulation element 14 is arranged between the bottom 13 of the casing 3 and the cell winding 2. The further insulation element 14 is also provided with thermally conductive particles 12 and is made of a silicone material.

[0044] The following materials can be considered in particular as materials for the compensating element 9: ethylene propylene diene monomer (EPDM), methyl rubber (IIR), fluororubber (FPM), polyacrylate rubber (ACM), silicone rubber (VMQ) or fluorinated silicone rubber (F-VMQ).

[0045] In principle, however, it is also conceivable to form the compensating element 9 from a thermoplastic elastomer (TPE) or from a thermoplastic material such as polyethylene (PE) or polypropylene (PP). In this embodiment, the compensating element 9 preferably includes elastically movable sections such as beading, film hinges or the like.

[0046] Such a compensating element 9 with elastic shaping is shown in FIG. 9. In this embodiment, the elasticity and softness of the compensating element 9 is provided by a circumferential, concentrically arranged beading 16. As a result, the compensating element 9 is shaped in the manner of a bellows-shaped membrane so that the pole portion 7 can move in the axial direction.