METHOD OF PRODUCING AN ENCAPSULATED BATTERY CELL

Abstract

A method of producing an encapsulated battery cell (1), includes: a) braiding a battery cell (1) with a fibre roving (8ba) to create a braid around the battery cell (1); b) impregnating the braid with a resin material (8ad); and c) curing the resin material (8ad).

Claims

1. A method of producing an encapsulated battery cell (1), comprising: a) braiding a battery cell (1) with a fibre roving (8ba) to create a braid around the battery cell (1); b) impregnating the braid with a resin material (8ad); and c) curing the resin material (8ad).

2. The method according to claim 1, wherein a ceramic material is used for the fibre roving (8ba).

3. The method according to claim 1, wherein the fibre roving (8ba) comprises a material having a strength retention of at least 50% at 800 degrees Celsius.

4. The method according to claim 1, wherein the fibre roving (8ba) comprises a material having a thermal conductivity of at most 0.25 W/(m.Math.K) at 800 degrees Celsius.

5. The method according to claim 1, wherein the fibre roving (8ba) comprises a material with a low or negative expansion coefficient.

6. The method according to claim 1, wherein the resin material (8ad) comprises a fire-retardant material.

7. The method according to claim 1, wherein the braid is tightly applied to an outer casing (3) of the battery cell (1).

8. The method according to claim 1, wherein the braiding is carried out such that the braid protrudes at at least one end relative to the battery cell (1).

9. The method according to claim 8, wherein the braid is formed at said one end with a reduced dimension (r) compared to a remainder of the braid.

10. The method according to claim 8, wherein the braid is formed at said one end with an opening toward the exterior (E).

11. The method according to claim 1, further comprising curing the resin material (8ad) by Ultra Violet, UV, radiation or at a temperature of at most 80 degrees Celsius.

12. The method according to claim 1, wherein the resin material (8ad) comprises a low temperature exothermic reactive material and is cured by a catalyst material.

13. The method according to claim 1, wherein a plurality of battery cells (1) are arranged continuously one behind the other as a battery sell string, and the method includes continuously feeding the battery cell string to a braiding device (8b), and the braiding device (8b) continuously provides the battery cells (1) with said braid as a continuous braid.

14. The method according to claim 13, further comprising placing a spacer material (7) between adjacent ones of the battery cells (1) in the string prior to feeding said battery cell string to the braiding device (8b).

15. The method according to claim 13, further comprising feeding the battery cells (1) to the braiding device (8b) through a tubular feed (8aa), with said feed (8aa) being cut obliquely to a course thereof, whereby the battery cell string is already provided with the braiding on one side, while the battery cell string is still supported by the tubular feed (8aa) on an other side.

16. The method according to claim 13, wherein the battery cell string together with the braid is passed through a first bath (8d) with the resin material (8ad) and then through a second bath with a catalyst material, an Ultra Violet, UV, irradiation device, or a temperature curing device (8e) to cure the resin material.

17. The method according to claim 13, further comprising cutting the battery cell string to length between the individual battery cells (1) using a cutting device (8g).

18. An encapsulated battery cell (1) formed by the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Further advantages and characteristics of the invention will now be described in exemplary fashion with reference to the attached drawings.

[0066] FIG. 1 shows an encapsulated battery cell manufactured according to the method of the invention and a corresponding spacer element in various views;

[0067] FIG. 2 shows a schematic representation of a device for carrying out the method according to the invention; and

[0068] FIG. 3 shows a detail of the device of FIG. 2.

DETAILED DESCRIPTION

[0069] In FIG. 1, an encapsulated battery cell manufactured according to a method according to the invention is shown on the left-hand side. The encapsulated battery cell as a whole is designated by reference numeral 1. At the bottom left, the encapsulated battery cell 1 is shown in longitudinal section along longitudinal axis L. A top view of the encapsulated battery cell 1 in the region of the cathode (positive terminal) is shown at the top left.

[0070] As can be seen from the bottom left illustration in FIG. 1, the encapsulated battery cell 1 is designed in the form of a cylindrical rod cell with longitudinal axis or axis of symmetry L. Reference numeral 2 indicates the so-called cell chemistry, which is also colloquially referred to as a jelly roll. The cell chemistry 2 is enclosed in a casing or cell can 3 made of metal, for example steel or aluminium, which also represents the anode of the encapsulated battery cell 1. The can 3 is open at one end (at reference numeral 1a) of the encapsulated battery cell 1. Here the cathode 4 is located, which protrudes slightly from the can 3 and is separated from the anode by an insulator ring or gasket 5. The actual battery cell from cathode 4 to the closed end of the can 3 has a dimension h in the direction of the longitudinal axis L. The can 3 has a maximum outer diameter d or a corresponding maximum outer radius R.

[0071] As can be seen from the illustration at the bottom left of FIG. 1, the entire battery cell, i.e., in particular the can 3, is surrounded on the outside by a braided sheathing made of ceramic fibres, which braided sheathing 6 is wound directly onto the can 3 from the outside and the impregnated with a resin, which resin is subsequently cured. Said braided sheathing 6 is also (alternatively) referred to as container or sleeve in FIG. 1. The braided sheathing 6 is tapered at the ends of the encapsulated battery cell 1; in these areas the braided sheathing 6 is located at a distance r from the longitudinal axis L, while in the other areas the respective distance equals R, r<Rwith a possible exception in respective transitional areas.

[0072] The illustration at the top left in FIG. 1 showsas already mentioneda top view of the encapsulated battery cell 1 in the region of the cathode 4. It can be seen from the illustration that the braided sheathing 6 is arranged in restricted circumferential regions only at said distance r from the longitudinal axis L. In between there are areas in which the distance of the braided sheathing 6 from the longitudinal axis L is equal to R, such that in said latter areas the can 3, i.e., the anode is freely accessible to contact the encapsulated battery cell 1 electrically. The cathode 4 is accessible from the outside through a central aperture in the insulator ring 5.

[0073] In order to achieve the said geometry of the braided sheathing 6 when winding the ceramic fibres onto the can 3, a corresponding embodiment of the invention provides for arranging spacer elements 7 made of an electrically insulating material at the respective axial ends of the battery cells prior to braiding, as shown schematically in the right-hand part of FIG. 1. The spacer elements 7 have a first portion 7a in which they are complementary to the geometry of the braided sheathing 6 in the region of the cathode 4, as already described. In other words, when the spacer element 7 is arranged with its first section 7a in the region of the cathode 4 of the battery cell 1, winding or wrapping of the ceramic fibre results in a braided sheathing 6 with a geometry as specifically shown in the upper left of FIG. 1 (at reference numeral 6a).

[0074] The spacer elements 7 also have a second section 7b, in which they have a simple circular cross section with radius r. Overall, the spacer elements in the first section 7a are approximately cross-shaped, while they have a circular shape in the second section 7b.

[0075] When the ceramic fibre is wrapped around said second section 7b of spacer element 7, the result is a design of the braided sheathing 6 as shown in the lower area of the encapsulated battery cell 1 according to FIG. 1 at the bottom left: the braided sheathing 6 here simply has a tapered section with a clear inner radius r (at reference numeral 6b). This follows from the fact that, in a corresponding embodiment of the invention, a plurality of naked battery cells (i.e., without encapsulation) are arranged one behind the other in the axial direction with a respective spacer element 7 interposed in each case, and are then continuously encapsulated with the ceramic fibre and resin. In each case, a given spacer element 7 then helps to form in the region of the cathode 4 of a first battery cell 1 the geometry 6a shown at the top left in FIG. 1 for the braided sheathing 6, while the same spacer element 7 helps to form in the region of a directly adjacent second battery cell 1 the geometry for the braided sheathing 6 as shown at reference numeral 6b.

[0076] The individual battery cells 1 are then separated again by cutting the braided sheathing 6 in the area of the end faces of the battery cells 1preferably by cutting in the area between the geometries 6a and 6b, such that the braided sheathing 6 has respective corresponding openings to the exterior E. The spacer elements 7 are then also removed (and destroyed), resulting in a design as shown in particular at the bottom left of FIG. 1.

[0077] FIG. 2 schematically shows a device 8 which is designed and provided for carrying out a method according to the invention, in particular for mass production. The device 8 comprises, from left to right in a conveying direction CD, a roller feed device 8a designed for pushing naked battery cells 1 arranged axially one behind the other in the form of a string, a braiding device 8b for wrapping the battery cells 1 with a ceramic fibre 8ba, a guide device 8c for guiding the ceramic fibre or corresponding fibre rovings 8ba when wrapping the battery cell strings, a (first) bath 8d with a resin material 8ad for impregnating the ceramic fibre 8ba of the wrapped battery cell strings, a curing device 8e for curing the resin material 8ad, a roller conveyor device 8f designed for drawing the line of encapsulated battery cells, a cutting device 8g (e.g., a circular saw) for cutting to length or separating the encapsulated battery cells, and a further conveying device 8h for transporting the separated encapsulated battery cells 1 away.

[0078] The ceramic fibre 8ba and the (cured) resin material 8ad together form the braided sheathing 6, which has already been described in detail above with reference to FIG. 1.

[0079] The braiding device 8b comprises a plurality of spools 8bb for feeding a respective fibre roving of said ceramic material (i.e., ceramic fibre 8ba). The braiding device 8b is used for braiding a battery cell (or a plurality of such cells) 1 with said fibre roving 8ba in order to create a braid around the battery cell(s) 1.

[0080] The (first) bath 8d with said resin material 8ad is used for impregnating the braid with the resin material 8ad.

[0081] The curing device 8e is used for curing the resin material 8ad. The curing device 8e may be a UV curing device or a low temperature curing device, depending on the type of resin material used. If a low temperature exothermic reactive resin material is used, in addition to the (first) bath 8d, there may be a (second) bath with a catalyst material located downstream in the direction CD with respect to the (first) bath 8d, which is not shown in FIG. 2.

[0082] As further shown in FIG. 2, the roller feed device 8a may comprise or co-operate with a tubular feed 8aa. This is shown again in more detail in FIG. 3.

[0083] FIG. 3 shows several naked battery cells 1 arranged one behind the other in a string. A respective spacer element 7 is located between every two battery cells 1, as described in detail, for example, above on the basis of FIG. 1. Reference numeral 8aa indicates the tubular feed already mentioned.

[0084] This tubular feed 8aa is cut off at an oblique angle at its rear end in the conveying direction CD, similar to a medical needle. In this way, the battery cells 1 emerging from the tubular feed 8aa can already be braided from above by means of the braiding device not shown in FIG. 3 (cf. FIG. 2), while the battery cells 1 are still supported against gravity and guided by the extended design of the tubular feed 8aa in the lower area.