Foil for forming packaging and housing parts

Abstract

A foil for forming a packaging unit or a housing unit includes: a coupling layer configured to be bonded to a metal foil; a core layer having a layer thickness greater than at least half the foil thickness, and a sealing layer configured to be in permanent contact with the electrolyte.

Description

TECHNICAL FIELD

[0001] The present invention relates to a foil for forming a packaging component and a housing component. The invention particularly relates to a foil which together with a diffusion barrier can form a reliable packaging or housing component for electrolyte-containing substances or electrolyte-containing assemblies. BACKGROUND

[0002] Electrolyte-containing substances and assemblies have a wide range of applications in the electrical, automotive and chemical industries. Electrolyte-containing substances are packaged for further processing or also form corresponding assemblies in the form of electronic components such as batteries. In particular, the latter, i.e. batteries, are the subject of further intensive research and development in the field of electronic consumer goods, electric cars and stationary storage of electrical energy.

[0003] The packaging and housing of such electrolyte-containing substances or assemblies must have certain properties in order to ensure the safe containment of the substances and assemblies. In particular, the function of the diffusion barrier plays an important role here, which effectively prevents the leakage and loss of electrolyte components. Metal foils are generally used for this purpose, which generally provide a satisfactory diffusion barrier. Metal foils can also be easily formed in packaging or housing components, since they either retain the shape obtained by compression molding very well or in any case remain flexible and ductile. In this way, it is possible to reliably provide containers such as bottles or pouches for packaging or even housings for permanent containment.

[0004] Despite the fact that metal foils generally provide a good diffusion barrier and are easy to ductile, they have certain disadvantages in terms of sealing. It is clear that both packaging and housing must ensure the reliable containment of the substances or assemblies. Therefore, the aim is generally to reliably join and seal the metal surfaces at the seams in order to ensure the sealing of the electrolyte. Metals can generally be welded or brazed well, but this is associated with high heat input and energy consumption.

[0005] Therefore, there is a need for reliably combining a diffusion barrier in order to produce packaging or housing components which ensure the reliable containment of electrolytes, electrolyte-containing substances or corresponding assemblies. Therefore, in particular, it is the object of the present invention to provide a foil for forming a packaging or housing unit which ensures the reliable containment of electrolytes and achieves an overall positive balance of advantages in terms of processing, weight and energy consumption. SUMMARY

[0006] The foil according to patent claim 1 provides the above-mentioned and further advantages. Further advantageous embodiments of the invention are specified in the dependent patent claims.

[0007] According to an aspect of the present application, a foil for forming a packaging or housing unit is provided, comprising a coupling layer configured to bond to a metal foil, a core layer having a layer thickness of at least more than half of the foil thickness, and a sealing layer configured to be in permanent contact with an electrolyte. BRIEF DESCRIPTION OF DRAWINGS

[0008] Embodiments of the present application will now be described in more detail with reference to the following drawings. The description is merely intended to provide a better understanding of the teaching of the present application and its related advantages, but is not intended to be limiting in any way. These drawings show the following:

[0009] Figure 1 schematically illustrates the basic structure of a foil according to an embodiment of the present application;

[0010] Figure 2 schematically illustrates the basic structure of a packaging or housing intermediate product with a foil according to an embodiment of the present application;

[0011] Figures 3A to 3E schematically illustrates possible shapes of a packaging or housing component made of a foil according to an embodiment of the present application;

[0012] and

[0013] Figure 4A &4B schematically illustrates possible applications of a foil according to an embodiment of the present application. DETAILED DESCRIPTION

[0014] Figure 1 schematically illustrates the basic structure of a foil according to an embodiment of the present application. The foil 10 is used for forming a packaging or housing unit, in particular for containing an electrolyte, an electrolyte-containing substance or an electrolyte-containing assembly. In conjunction with further embodiments, these uses as well as the shapes of the corresponding packaging and housing are described in more detail. The foil 10 can preferably be a co-extruded product, wherein the materials of the individual layers are brought together in a molten state in order to solidify as the foil 10 at the extrusion die or outlet. In this way, the respective layer properties and layer strengths (thicknesses) can be provided by the respective intermediate product and its quantity ratio. If polypropylene or other polyolefin-based plastics are used, the foil 10 can generally be provided as a cast foil, in particular a cast polypropylene (CPP) foil.

[0015] The foil 10 comprises a coupling layer 101 which is configured to bond to the metal foil. Optionally, an adhesion promoter can be used to bond the coupling layer 101 such that the properties of the coupling layer 101 are tailored to bond directly to the metal foil or to bond to the metal foil via the adhesion promoter. Such an adhesion promoter can be provided by adding an adhesion promoter additive in the coupling layer, e.g. during extrusion. Further, the adhesion promoter can also be provided by a (separate) adhesive system or adhesive (glue). In the latter case, the adhesion promoter, e.g. in the form of the adhesive system, can at least indirectly influence the properties of the coupling layer through the metal foil. The coupling layer 101 can consist of or at least comprise a polyolefin-based plastic, such as polypropylene. The coupling layer 101 can be subjected to a corona pre-treatment so that it can be well bonded to the metal foil or metal layer in subsequent manufacturing steps by an adhesion promoter (e.g. adhesive system on aluminum) (e.g. using one).

[0016] Preferably, the coupling layer 101 can be subjected to a corona pre-treatment. By such a corona pre-treatment, the surface tension of the coupling layer can be increased compared to a layer without such a pre-treatment. For example, the surface tension can be increased to a value of > 30 mN / m (dyne), preferably > 38 mN / m (dyne). The surface tension can be measured using a dyne test ink pen or by contact angle measurement, and is thus a feature of the respective embodiment. The corona pre-treatment can advantageously improve the bonding of the coupling layer to the metal foil, in particular when an optional adhesion promoter or adhesive is used. The coupling layer 101 can also be bonded directly to the metal foil by thermal lamination. The layer thickness of the coupling layer 101 can be in the range of 4 pm to 20 pm, or preferably in the range of 5% to 20% of the foil 10 thickness.

[0017] The foil 10 further comprises a core layer 102 which in particular contributes to achieving the desired elasticity, toughness and / or performance strength of the overall structure of the foil 10 and / or the packaging or housing component. Thus, the layer thickness dKEof the core layer 102 is at least greater than half of the foil thickness d, preferably even substantially equal to or greater than 70% of the foil thickness d, for other reasons. The layer thickness of the core layer 102 can be in the range of 20 pm to 200 pm.

[0018] The foil 10 also comprises a sealing layer 103, which is configured to be in permanent contact with the electrolyte. The sealing layer can also be well sealed with another sealing layer, for example also at another point with an area of the same sealing layer of the same foil, to provide a reliable seal. The sealing can be performed by heat induced heat welding or ultrasonic welding. The sealing layer is characterized by forming a high strength sealing joint. The sealing layer is further characterized in that it has a low sealing point, i.e. it has been sealed at a relatively low temperature, preferably at a temperature of 100°C. A special PP polymer type can be used for this purpose, which is modified during production such that a sealing point is achieved which is lower than the sealing point of normal unmodified PP, so that a highly durable sealing joint can be provided. Furthermore, the sealing layer is characterized in that the sealing can still function without any significant change in sealing ability, even if the sealing surface is wetted by the electrolyte.

[0019] Examples of such electrolytes include lithium phosphates, such as lithium hexafluorophosphate, dissolved in ethylene carbonate, dimethyl carbonate and / or diethyl carbonate. The advantageous properties against permanent contact with the electrolyte can be chemical resistance and migration behavior of the electrolyte solution through the foil 101. Otherwise, migration of the electrolyte solution through the foil would erode or reduce the adhesion of the metal foil. This can lead to delamination, however, embodiments of the present invention effectively prevent delamination. The required resistance can be achieved, for example, by using cast polypropylene, cast PP. The layer thickness of the sealing layer 103 can be in the range of 2 to 20 pm, or preferably in the range of 5 to 20% of the foil 10 thickness.

[0020] The above layer thicknesses result in a total layer thickness d of the foil 10, depending on the application. For example, for use in mobile devices, the total thickness of the foil can be 30 to 50 pm, or for example 40 pm. For high-voltage batteries in the automotive industry, the foil thickness can be in the range of 70 to 90 pm, preferably about 80 pm. If aluminum is chosen as the metal, the foil 10 can be referred to as an aluminum laminated foil, or ALF for short, which is preferably provided as a three-layer co-extruded foil made of CPP for lamination.

[0021] Figure 2 The basic structure of a packaging or casing intermediate product with a foil according to an embodiment of the present invention is schematically shown. In particular, a semi-finished product 20 is shown, which is also film-like or plate-like and comprises a foil 10 for forming a packaging or casing unit, as described elsewhere in the present disclosure. The semi-finished product further comprises a metal layer 200 in the form of a metal foil, metal plate or metal sheet. Advantageously, the metal layer is an aluminum foil with a material thickness in the range of 10 to 100 pm or 30 to 50 pm.

[0022] The semi-finished product 20 is bonded to the foil 10 with an adhesive 210, preferably a laminating adhesive, a two-component adhesive or a polyurethane, PU, adhesive. In an advantageous embodiment, the foil 10 is first subjected to a corona pretreatment, which improves the bonding to the metal layer 200 by means of the adhesive 210. Furthermore, an outer protective layer 300 is provided on the metal layer 200, which consists of or at least contains, for example, polyamide (PA) and / or polyethylene terephthalate (PET). The protective layer 300 can be bonded to the metal layer 200 with a further adhesive 320. The material thickness of the protective layer 300 can be in the range of 10 to 30 pm or 15 to 20 pm. The typical layer thickness of the entire composite 20 is, for example, approximately 140 pm. If aluminum is used as the metal layer, this layer can be laminated to at least a three-layer composite with the above-mentioned co-extruded foil and polyamide foil on one side by means of an adhesive system, for example, co-extruded PP-aluminum-PA-PET.

[0023] Figures 3A to 3E Possible shapes of the packaging or housing parts made of foil according to embodiments of the application are schematically shown. Figure 3A A simple pocket shape 910 is shown, in which the semi-finished product 20 is folded along the crease 911 into a rectangle and welded at the remaining sides in the area 912. The sealing layers 103 of the semi-finished product 20 advantageously meet at these points and provide a reliable containment of the volume V by means of welding (here, in the illustration, the sealing layers 103 of the semi-finished products 20A and 20B are fused in the area 103A / B). One or more access points 914 can be incorporated in the welded area 912, which provide access to the internal volume V and thus, for example, in the case of a battery housing, electrical contacts, or in the case of a packaging, closures. A cross-sectional view of the pocket shape 910 containing the volume V along the axis 913 is shown in the right-hand area.

[0024] Figure 3B and 3C Further pocket shapes are shown, which can essentially assume a rectangular basic shape, as in the case of the pocket 920( Figure 3B ), but also any desired shape, as in the case of the pocket 920'( Figure 3C ). With the foil and the corresponding semi-finished product according to the application, a pocket of almost any shape can be obtained by welding the corresponding edge areas 922, 932, in which the corresponding sealing layers can again be placed on top of one another and welded. One or more access points 914 can also be provided in these shapes, the corresponding position of which can advantageously be placed in the most advantageous position for the specific use, since the pocket structure with the foil according to the application or the semi-finished product here offers great flexibility. In both cases, the cross-sectional views 920 / 920' with the volume V are schematic.

[0025] Figure 3D A cylindrical 940 is shown, which is obtained by simply rolling the semi-finished product 20. A cylindrical or cup-shaped pocket can also be produced in this way by at least one welded area 941. Figure 3E A prismatic pocket 950 is shown, which is composed of one or more folds and one or more welded areas 951 (and possibly also 952, 953).

[0026] Figure 4A A possible use of the foil according to an embodiment of the application is schematically shown. In this use, a battery 980 is provided, which is, for example, a rechargeable battery, a lithium-ion battery, a lithium-polymer battery, a solid-state battery, etc. The electrolyte-containing assembly comprises an electrode structure 981 and an electrolyte 983, wherein the inner sealing layer 103 of the semi-finished product 20 is in contact with the electrolyte 983 (see inset). In a pouch cell, i.e. a so-called "pouch cell", a plurality of rectangular layers of positive and negative electrodes and conductor foils are typically stacked in a sandwich configuration with corresponding separation layers. The electrodes typically discharge on one side. The outer wrapping and sealing is provided by a deep-drawn welded plastic aluminum plastic multilayer foil.

[0027] The housing comprises a pocket made of a foil 10 or semi-finished product 20 according to the application, which is obtained by welding at least one area 987. This allows the greatest flexibility in the shape of the battery housing, so that a corresponding battery, for example a so-called pouch or pouch cell, can be provided in an advantageous manner. Access points in the form of contacts 984 can be provided in one of the welded areas 987, which lead out the battery contacts 985 from the inner volume V and from the assembly in an electrically insulating manner.

[0028] For such a use, a semi-finished product, for example a pouch cell film structure "CPP film - aluminum foil - PA foil", can be made into (generally) rectangular cavity shapes by stamping or compression molding, wherein two of these shapes are sealed together by heat welding or ultrasonic welding to form a housing for the battery assembly (coil and electrolyte). After sealing (welding), the sealing layer remains permanently reliably on the aluminum foil, which is laminated by the adhesive system. Even in the event of damage or end of service life, in the event of delamination or tearing / separation of the sealing seam, a residual foil, for example an aluminum foil, should remain on the metal layer. At this point, it should be mentioned that "permanently" generally means at least the duration of the planned service life or use of the respective product (packaging, housing, battery, etc.) in the context of the present disclosure. Even in the worst case of delamination, embodiments of the present application still offer a significant advantage, namely that a residual layer, for example a PP, remains as a thin protective layer on the metal foil.

[0029] This is achieved in particular by the composite structure of the semi-finished product, since under maximum load the composite within the foil breaks, i.e. the coupling layer separates from the core layer and / or the core layer separates from the (welded) sealing layer, and the metal foil remains protected by the residual foil from contact with the electrolyte. In any case, for example, the residual layer of the foil remains on the aluminum and can advantageously prevent the electrolyte solution from coming into contact with the aluminum foil. The delamination can also be evidenced by a so-called white break indicator, for example, the PP layer remains on the aluminum foil.

[0030] Figure 4B A possible use of the foil according to an embodiment of the application is schematically shown. In this use, the packaging 990 is provided in the exemplary form of a stand-up pouch. To this end, the semi-finished product is produced by a combination of one or more folds 991 and one or more welded areas 992. An access point in the form of a closure 993 can be provided in one of the welded areas, which enables the packaging to be filled and / or emptied. By using the foil 10 or semi-finished product 20 according to the application, a reliable product packaging can be obtained, which also reliably contains the electrolyte-containing substance.

Claims

1. A foil for forming a packaging or housing unit, comprising: - a coupling layer configured to bond to a metal foil; - a core layer having a layer thickness of at least more than half of the foil thickness, and - a sealing layer configured to be in permanent contact with an electrolyte.

2. The foil according to claim 1, wherein, The coupling layer is configured to bond to a metal foil by being subjected to a corona pre-treatment which facilitates bonding to the metal foil by means of an adhesion promoter.

3. The foil according to claim 2, wherein, The adhesion promoter comprises an adhesive or an adhesive system.

4. The foil of claim 1, wherein, The coupling layer is configured to bond to a metal foil by its inclusion of an adhesion promoter additive which facilitates bonding to the metal foil.

5. The foil according to claim 4, wherein, The coupling layer is directly bonded to the metal foil by means of the adhesion promoter additive.

6. The foil according to any one of claims 1 to 5, wherein, The sealing layer forms a welded or sealed connection even if previously wetted by an electrolyte.

7. The foil according to any one of claims 1 to 6, wherein, The coupling layer, the core layer and the sealing layer are present in a co-extruded structure.

8. The foil according to any one of claims 1 to 7, wherein, The coupling layer, the core layer and / or the sealing layer comprise a polyolefin-based plastic.

9. The foil according to claim 8, wherein, The polyolefin-based plastic is cast polypropylene, cast PP.

10. A semi-finished product for forming a packaging or housing unit, comprising a foil according to any one of claims 1 to 9 and a metal foil bonded to the coupling layer.

11. The semi-finished product according to claim 10, wherein, The metal foil is an aluminum foil.

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