HK1160702B - Thin film battery - Google Patents

Description

Thin film battery

Technical Field

The present invention generally relates to thin film galvanic cells.

Background

Electrochemical elements (i.e., batteries) are known in a wide variety of physical forms. In most cases, they have a mechanically robust housing and are in the form of round, button or prismatic cells (cells). In such a battery cell, positive and negative electrodes, a separator, and an electrolyte are provided. The housing of such battery cells is usually made of steel, stainless steel alloys or aluminum.

However, in some applications a very thin battery with a flexible casing is required. These applications include active Radio Frequency Identification (RFID) tags, PCMCIA cards, smart cards, and the like. Batteries for such applications must be flexible and compact, deliver high energy density and specific energy at low self-discharge rates, and should have reliable seals. Such sealing is extremely important because moisture should be prevented from entering the battery to avoid leakage and self-discharge, and from drying out due to release of organic solvents in the electrolyte even when the battery is deformed or mechanically stressed. In addition, the battery should be manufactured in a cost-effective and reliable manner.

Different thin film batteries exist in the prior art, most of which utilize lithium as the anode material.

For example, US5,989,751 discloses a lithium primary cell having a flexible and compact design. The battery cell has an electrolyte comprising a composite cathode. The encapsulation is provided using spacers and polymer sheets.

US 2003/0228517a1 shows a thin battery having a package formed by two plastic sheets sealed to each other. The thin battery cells described in this document are stacked to form a larger electrochemical element. The plastic sheet is metallized in certain areas to form electrical contacts to the electrodes of the battery cells.

US 2005/0239917 also discloses a thin film lithium battery in which the anode is printed on a copper current collector using an ink based on lithium metal powder. The anode and cathode current collectors are sealed around the perimeter of the cell with a polyester sealant frame.

US 6,752,842B2 discloses a thin film battery cell formed by printing different layers on top of each other.

The above-described battery has not been completely satisfactory in terms of sealing quality and cost efficiency at the time of production.

Disclosure of Invention

The present invention relates to a flat battery including a package formed of a cathode, an anode, and a separator layer sandwiched between the cathode and the anode. A sealing frame extends circumferentially around the package. The battery further includes a first current collector contacting the anode and a second current collector formed of a metal foil and contacting the cathode, wherein the first and second current collectors partially cover the sealing frame on regions adjacent to the package, respectively.

The battery also includes a first polymer jacket layer disposed on the first current collector and a second polymer sheet disposed on the second current collector, the first and second polymer sheets extending circumferentially beyond the current collectors and the sealing frame and being sealed together to form an outer jacket for the battery.

The invention also relates to a method for producing a flat cell, comprising the following steps:

(a) a first polymeric jacket layer is provided,

(b) providing a first current collector and disposing it on the first polymeric sheet,

(c) applying an anode material to the first current collector,

(d) a second polymeric jacket layer is provided which,

(e) providing a second current collector and disposing it on the second polymeric sheath layer,

(f) providing a sealing frame having an inner contour substantially corresponding to an outer contour of the anode material and the separator on the first current collector,

(g) disposing the frame on one of the current collectors, the frame covering an outer periphery of the current collector,

(h) a cathode material is provided and disposed on a second current collector,

(i) a separator layer is provided and disposed on the cathode material,

(j) assembling the flat cell by inverting (turning) one of the two polymer sheathing layers and disposing it on the other polymer sheathing layer such that the separator layer is sandwiched between the cathode material and the anode material, the sealing frame extending circumferentially around the anode material, the cathode material, and the separator, and

(k) the first and second polymeric sheath layers are sealed together over a region circumferentially extending beyond the current collector to form an outer sheath of the battery package.

The first and second polymeric jacket layers sealed together to form the outer battery jacket help to prevent water or other liquids from entering the battery cell and forming conductive paths that may induce high self-discharge rates. In addition, the electrolyte is prevented from leaving the cell, thereby avoiding drying out of the cell. A sealing frame extending circumferentially around the package formed by the anode, cathode, separator and electrolyte also facilitates obtaining a high sealing quality. Due to the fact that the sealing frame extends circumferentially around the package, a double seal is provided when the first and second polymer sheets extend circumferentially beyond the frame. The current collector partially covering the sealing frame forms a first sealing area, and the polymer sheet circumferentially extending beyond the sealing area forms an additional second sealing area.

According to a preferred embodiment of the invention, the sealing frame is coated with a heat-sealable material. The sealing frame itself may be made of a polymer, such as nylon, Polyester (PET), polypropylene or any suitable polymer, in particular PET (polyethylene terephthalate, polyester resins). The coating may be constructed of a hot melt adhesive EVA (ethylene vinyl acetate) or EMA (ethylene methyl acrylate), or other suitable heat sealable material. Due to the coating, the frame can be easily sealed with the current collector and the polymer sheet. The sealing frame may also be constituted by two frame elements, each of these elements forming the frame itself. Typically, in assembling a cell, such a frame element is provided on the cathode side and another element is provided on the anode side, which two frame elements will be joined together to form a frame during the final assembly step. In the case of using two frame members, the spacer may be disposed with its periphery between the two frame members. When the two frame elements are joined together, the separator will thereby be held in place by the two frame elements, so that contact between the anode material and the cathode can be avoided in a very reliable and simple manner.

The first and second polymeric sheath layers may also be coated with a hot melt adhesive on the sides located on the first and second current collectors, respectively. The outer jacket may thus be formed simply by sealing the two polymer jacket layers together by applying heat in a lamination operation.

The polymer jacket layer may simply be a polymer sheet having a surface larger than the surface of the current collector on which it is placed. The entire current collector will then be covered by the polymer sheet, and the sheath formed by the two polymer sheets will thus not allow any part of the battery to be contacted except for the two contact protrusions.

Alternatively, the polymer sheath layer may also be formed from a polymer frame, which will typically be cut out of a polymer sheet and cover the outer contour of the current collector on which it is located. The use of such a frame has the advantage that the whole cell is thinner than when using a whole sheet and that the additional sealing is limited to the area where such sealing is really important, i.e. the outer contour of the current collector. On the other hand, it is easier to obtain certain desired cell surface characteristics when using a monolithic sheet than when using only a frame. Thus, a one-piece sheet would be preferred when a certain tackiness or a certain appearance is desired.

The current collector is preferably a metal foil, in particular a copper foil. Contact protrusions for externally contacting the battery may be formed integrally with such a copper foil, so that no additional contacts are required. However, instead of a metal foil, a metallized polymer film or sheet may also be used. According to a preferred embodiment of the invention, at least one of the current collectors is a prefabricated metal foil formed with a recess on its central area. Such a recess may constitute a receiving portion for the cathode mixture when the cathode mixture is applied to the current collector, and therefore, assembly of the battery will be facilitated.

Preferably, the anode material is lithium. However, other materials, such as zinc (Zn), cadmium (Cd), lead (Pb), hydrogen storage alloys, or any other suitable material may also be used for the anode without departing from the scope of the present invention.

According to a preferred embodiment of the invention, the cathode comprises manganese dioxide (MnO)₂) As the active material. Typically electrolytic manganese dioxide or EMD will be used for this purpose. However, other materials, such as nickel hydroxide, silver oxide, carbon monofluoride, or any other suitable material, may also be used for the cathode without departing from the scope of the present invention.

It should also be noted that the first and second polymeric sheath layers may be made from a single piece of sheet that is folded in between to form an outer sheath to seal the battery. The advantage of this solution is that the fold line already provides one side that will be perfectly sealed.

The invention also relates to a method for manufacturing a battery according to claim 12. Preferred embodiments of the method will appear from the dependent claims and the description of the two preferred embodiments given below.

Drawings

The subject matter of the invention will be explained in detail in the following description with reference to the drawings, in which:

fig. 1 is a sectional view of a flat battery according to a first embodiment of the invention;

fig. 2 is a sectional view of a flat battery according to a second embodiment of the invention;

fig. 3(a) is a top view of a first pre-assembly portion of the flat cell of fig. 1; and

fig. 3(b) is a top view of a second preassembly part of the flat cell of fig. 1.

Detailed Description

It should be understood that the following description is intended to set forth two particular embodiments of the invention, chosen to illustrate the drawings, but which are not intended to limit or restrict the invention except in the appended claims.

Fig. 1 shows a cross section of a flat cell according to the invention, while fig. 3(a) and 3(b) respectively show a top view of a preassembly part of the flat cell shown in fig. 1. More specifically, fig. 3(a) shows the upper layer of the battery shown in fig. 1, and fig. 3(b) shows the lower layer thereof.

Referring to fig. 3(a) and 3(b), a method for manufacturing the battery shown in fig. 1 according to the present invention will now be described.

First, the preassembly of the lower layer shown in fig. 3(b) will be described.

In a first step, a first rectangular polymeric sheet 24 is provided, coated on one side with a heat sealable material. It should be noted that although rectangular components are selected for use in the embodiments described herein, the individual components and the assembled battery may have any desired shape, such as rectangular with rounded edges, oval, circular, etc. A first current collector 18 is disposed on the side of the polymer sheet 24 that is coated with the heat sealable material. The current collector 18 is made of rectangular copper foil or other suitable metal foil and has a circumference that is smaller than the circumference of the polymer sheet 24, e.g., a few millimeters smaller on all sides. On one side, a contact projection 17 is provided which projects beyond the outer contour of the polymer sheet 24. Current collector 18 will be disposed in the center of first polymer sheet 24 such that the frame-like outer region of polymer sheet 24 is uncovered, as can be seen in fig. 3 (a).

In the next step, a first frame element 22a will be disposed over the first polymer sheet 24 and the first current collector 18. The frame element is a rectangular polyester frame 22, which has a thickness of the order of about 100 μm and is coated with a hot melt adhesive EVA (ethylene vinyl acetate) on its upper and lower surfaces. The outer perimeter of frame element 22a is less than the perimeter of polymer sheet 24 but greater than the perimeter of current collector 18, while the inner perimeter of frame element 22a is less than the perimeter of current collector 18. The frame element 22a will be positioned on the polymer sheet 24 and the current collector 18 symmetrically about the center of all components such that the inner region of the frame element 22a is located on the current collector 18 and the outer region of the frame element 22a is located directly on the polymer sheet 24.

The three elements, i.e., first polymer sheet 24, first current collector 18, and first frame element 22a, will be joined to one another. For this purpose, it is sufficient to apply heat and pressure, for example by using a heating block, so that the polymer sheet and the hot-melt coating on the frame element 22a will be melted and bonded to the metal foil situated in the middle. Alternatively, the three elements may also be temporarily glued together simply by applying heated needles at selected points.

In the next step, a lithium foil to form the anode 12 is disposed on the current collector copper foil 18. This is usually done in a low humidity environment to protect the lithium. The anode lithium foil 12 is also rectangular with a surface slightly smaller than the surface of the current collector 18. It is preferably disposed in the middle of the current collector 18 in a symmetrical manner so as to leave the frame-shaped outer region of the current collector 18 uncovered.

Referring now to fig. 3(a), a second polymeric sheet 26, which is identical to the first polymeric sheet 24 and therefore also coated with a heat sealable material, will be provided in the same manner. Second current collector 20 with second contact projections 19 will be disposed on the second polymeric sheet 26 in the same manner as described above with respect to first polymeric sheet 24 disposed on first current collector 18. In the next step, a second frame element 22b, identical to the first frame element 22a described above, will be disposed on the second polymer sheet 26 and the second current collector 20, as described above. The second polymer sheet 26, second current collector 20 and second frame element 22b will then also be joined to one another, as described above with reference to fig. 3 (a).

Once frame element 22b is positioned on the copper foil forming current collector 20 and has been joined thereto and polymer sheet 26 as described above, the mixture that will form cathode 16 is applied to the central region of current collector 20 in place of the lithium foil forming anode 12. The boundary of this central region is defined by a frame element 22b, which frame element 22b forms a wall that holds the mixture in place. The mixture preferably comprises manganese dioxide as the active cathode material, although other suitable cathode materials may be selected without departing from the scope of the invention. In addition to the active cathode material, the mixture also includes an electrolyte, which is typically a lithium salt, such as lithium perchlorate (LiClO), in an aprotic organic solvent mixture₄) Lithium hexafluorophosphate (LiPF)₆) Or lithium trifluoromethanesulfonate (LiCF)₃SO₃) Such as PC: EC (propylene carbonate: ethylene carbonate), EC: DME (ethylene carbonate: dimethoxyethane) or EC: DMC (ethylene carbonate: dimethyl carbonate). Any other suitable electrolyte may also be employed. In addition, the cathode mix includes a conductive phase to promote conductivity and increase the utilization of active materials, such as conductive carbon, graphite, or other suitable materials. The mixture also includes a substance, such as PTFE (polytetrafluoroethylene) or PVDF, that acts as a binder to hold the various components together.

After the cathode mixture forming the composite cathode 16 is applied, a porous membrane, such as a PE or PP membrane, serving as the separator 14 is disposed on the cathode 16, as is well known in the art. For the example shown here, the outer contour of the insulating body 14 corresponds to the inner contour of the two frame elements 22a, 22 b. The separator may also have a larger surface than the cathode and extend circumferentially beyond the cathode. This solution will generally be preferred as it allows to avoid the cathode and the anode to contact each other. To hold the insulating body in place, the insulating body may be disposed between the two frame members along the outer periphery of the insulating body.

The pre-assembled unit shown in figure 3(b) comprising the first polymer sheet 24, the first current collector 18, the frame element 22a and the anode 12 can now be assembled with the pre-assembled unit shown in figure 3 (a). To this end, one of the two pre-assembled units is turned over and the two halves are superimposed so that the two frame elements 22a, 22b are aligned with each other and form a frame 22. The anode 12 is thus in contact with the separator 14 and the outer contours of the two polymer sheets 24, 26 are now superposed on each other. It should be noted that a unitary frame may also be used in place of the frame described herein comprising two frame elements. And the frame is preferably provided on the cathode side before the two units shown in fig. 3(a) and 3(b) are assembled to each other, as described below with respect to the second embodiment shown in fig. 2.

As shown in fig. 1, the anode 12, separator 14 and cathode 16 then form an approximately block-shaped package 10 at the center of the cell, and a frame 22 formed by frame members 22a, 22b surrounds the package 10. The inner contour of the frame 22 corresponds to the outer contour of the package 10 and the height h of the frame 22 corresponds to the height h of the package 10 formed by the anode 12, cathode 16 and separator 14. The outer peripheral region of the current collector 18 protruding out of the anode 12 is located on a region of the sealing frame 22 close to the package 10, i.e., on the inner peripheral region of the frame 22, thus partially covering the frame. As can be seen in fig. 1 and 2, approximately half of the surface of frame 22 is covered by current collectors 18,20, while the outer peripheral area of frame 22 is not covered by current collectors 18,20 and directly contacts polymer sheets 24, 26 when the cell is assembled.

In the laminating operation, the hot melt adhesive coating on the contacting surfaces of the frame elements 22a, 22b is melted so that the two frame elements 22a, 22b are now finally joined to form one frame 22. If this step is not done beforehand, the frame elements 22a, 22b will also be joined with the current collectors 18, 20. At the same time, the two polymer sheets 24, 26 coated with a heat-sealable material on the inner sides in contact with each other are sealed together along their outer periphery over an outer sealing area of width W. The polymer sheets 24, 26, which serve as the polymer jacket layer for forming the outer jacket, will typically have a thickness of 50-75 μm. In the first step, this lamination operation may be limited to being performed on three sides of the cell, with no fourth side being sealed for a while. In this case, a vacuum-pumping operation is performed in the next step to remove air, steam, moisture, etc. from the battery. While the evacuation is taking place, the fourth side will be subjected to a lamination operation to completely seal the cell. It is also possible to seal all four sides in one step while evacuating the cell, but this is somewhat difficult to handle. Since this evacuation step takes longer than the previously described assembly steps, the cells can be grouped during evacuation and during sealing of the fourth side, for example on a rotating assembly diode or on a conveyor belt, even if the previous assembly steps have been performed separately.

It should be noted that instead of two separate sheets 24, 26, it is also possible to use only one polymer sheet. In this case, first current collector 18, first frame member 22a and anode 12 would be applied to one half of the sheet as described above, while second current collector 20, cathode 16, second frame member 22b and separator 14 would be disposed on the other half, as previously described with respect to the two separate sheets 24, 26. The polymer sheet is then folded along the middle to assemble the cell, and the lamination operation described above is then continued. One advantage of this method is that there is one side (i.e. the side that is folded) that does not need to be sealed and it is easier to align the two halves forming the cell with each other.

Fig. 2 shows a second embodiment of a battery according to the invention. Like parts are denoted by like reference numerals, and only differences from the first embodiment will be described hereinafter.

In fig. 2, it can be seen that polymer frames 24 ', 26' are used in place of the polymer sheets 24, 26 shown in fig. 1. They have the same function as the polymer sheets 24, 26 in the first embodiment. The polymer frames 24 ', 26' may be cut out of the polymer sheet used for the polymer sheets 24, 26 of the first embodiment and will therefore also typically have a thickness of 50-75 μm. The outer contours of the polymer frames 24 ', 26' shown in fig. 2 correspond to the outer contours of the sheets 24, 26 shown in fig. 1 for the first embodiment. The inner contour of the frames 24 ', 26 ' is slightly smaller than the outer contour of the current collectors 18 ', 20 ' so that after assembly of the battery, the outer contour of the current collectors 18 ', 20 ' is covered by the frames 24, 26 '. The outer sheath formed by the two polymer frames 24 ', 26' is therefore not completely closed, the current collectors 18 ', 20' being uncovered at their centers. The uncovered centre may also act as a contact, so the contact protrusion shown in fig. 3(a), 3(b) is not necessarily required when the frame is used to form the sheath instead of a complete sheet.

Current collectors 18 ', 20 ' are copper foils as in the first embodiment, but a second current collector 20 ' is prefabricated and provided with a recess in its center. This recess forms a receiving portion for the cathode mixture 16', as can be seen in fig. 2. The first current collector 18 'may also be provided with recesses to receive the lithium foil forming the anode 12', but since the thickness of the anode is much smaller compared to the thickness of the cathode, the advantage of such recesses on the lithium side is less pronounced than the recesses forming the receiving portion of the cathode mixture on the cathode side.

The frame 22' is not formed by two frame elements 22a, 22b as described in relation to the first embodiment above, but by only a single frame. The frame will be disposed on the cathode side, i.e., on the second current collector 20 ' and the polymer frame 26 ', and these three portions will be joined together prior to application of the cathode mixture 16 ' as described above with respect to the first embodiment. The total thickness of the frame 22 'is less than the thickness of the package 10' formed from the active material and may be some value between the thickness of the spacer layer 14 and the thickness of the package 10. In the final lamination step, the frame 22 'coated on both sides with the hot-melt adhesive will be joined to the first current collector 18' and the polymeric frames 24 ', 26' forming the outer sheath.

With the embodiment shown in fig. 2, it is possible to obtain a battery having a total thickness that is less than that which can be achieved with the embodiment of fig. 1.

One of the major advantages of the cells described herein is the multiple sealing zones. As can be seen in fig. 1 and 2, the inner peripheral portions of the frames 22, 22 'are sandwiched between the two current collectors 18, 18', 20 'and are joined thereto by the molten hot melt adhesive coating of the frames 22, 22'. The current collectors 18, 18 ', 20 ' and the frame 22 located therebetween thus form a hermetically sealed "casing" that protects the package 10, 10 ' and thus the anode and cathode of the battery from moisture ingress.

In addition to this inner seal provided by the frame 22, 22 ' sealing with the current collector 18, 18 ', 20 ', an outer sealing sheath is also formed by two polymer sheath layers (i.e. by the polymer sheets 24, 26 in the first embodiment or by the polymer frames 24 ', 26 ' in the second embodiment) sealed to each other along the outer periphery. The sheath provides additional protection to the overall cell, including the current collectors 18, 18 ', 20'. In addition, polymer jacket layers 24,24 ', 26 ' are also sealed to frames 22, 22 ' at regions located circumferentially outward of current collectors 18, 18 ', 20 '. Finally, polymer jacket layers 24,24 ', 26' are sealed to current collectors 18, 18 ', 20' over their entire surfaces. Due to the low thickness of these single layers (i.e. the polymer sheath layer, current collector, active material and frame) the whole cell will remain flexible while achieving a perfect seal. The combination of a frame sandwiched between current collectors on the inner peripheral region and two polymer jacket layers on the outer region with the jacket formed by these jacket layers provides a good seal for the cell according to the invention.

Reference numerals

10. 10' Package

12. 12' anode

14. 14' insulation

16. 16' cathode

17 contact projection

19 contact projection

18. 18' first current collector

20. 20' second current collector

22. 22' frame

22a, 22b frame element

24. 24' first polymer jacket layer

26. 26' second polymeric sheath layer

h height

Width W

Claims (17)

1. A flat battery, comprising:

an encapsulation (10) formed by a cathode (16), an anode (12) and a separator layer (14) sandwiched between the cathode (16) and the anode (12),

a sealing frame (22, 22') extending circumferentially around the package (10),

a first current collector (18, 18 ') contacting the anode (12, 12'),

a second current collector (20, 20 ') contacting the cathode (16, 16'),

wherein the first and second current collectors (18, 18 '; 20, 20 ') partially cover the sealing frame (22, 22 ') over regions adjacent the package (10, 10 '), respectively, while upper and lower surfaces of peripheral outer regions of the sealing frame (22, 22 ') are not covered by the current collectors (18, 20) and are in direct contact with polymer sheets (24, 26) when the battery is assembled, the battery further comprising a first polymer sheathing layer (24, 24 ') provided on the first current collector (18) and a second polymer sheathing layer (26, 26 ') provided on the second current collector (20, 20 '), the first and second polymer sheathing layers (24, 24 '; 26,26 ') circumferentially protruding out of the current collectors (18, 18 '; 20, 20 ') and the sealing frame (22, 22 ') and being sealed together to form an outer sheath of the battery, wherein the polymer sheath layer (24, 24 '; 26,26 ') is also sealed to the frame (22, 22 ') in a region circumferentially outside the current collector (18, 18 '; 20, 20 ').

2. The flat battery as claimed in claim 1, wherein the sealing frame (22, 22') is coated with a heat-sealable material.

3. The flat battery as claimed in claim 2, wherein the sealing frame (22) is made of a polymer.

4. The flat battery as claimed in claim 3, wherein the sealing frame (22) is made of PET.

5. The flat battery as claimed in claim 2, wherein the sealing frame (22) comprises two frame elements (22 a, 22 b) lying one above the other.

6. The flat battery as claimed in claim 2, wherein said first and second polymer sheath layers (24, 24 '; 26, 26') are coated with a hot melt adhesive on the side lying on said first and second current collectors (18, 18 '; 20, 20'), respectively.

7. The flat cell of claim 6, wherein said first and second polymeric sheath layers (24, 26) are polymeric sheets that completely cover said current collectors (18, 20), wherein said polymeric sheets are disposed on said current collectors (18, 20).

8. The flat cell according to any of claims 1-6, wherein the first and second polymer jacket layers (24 ', 26') are polymer frames (24 ', 26') covering the outer contours of the current collectors (18, 20), wherein the polymer frames (24 ', 26') are disposed on the current collectors (18, 20).

9. The flat battery according to claim 8, wherein at least one of the current collectors (18') is a prefabricated metal foil provided with a recess in a central portion thereof.

10. The flat cell according to claim 9, wherein the anode (12) comprises lithium as an active material.

11. The flat cell of claim 9 wherein said cathode (16) comprises manganese dioxide (MnO)₂) As the active material.

12. The flat cell as claimed in claim 2, wherein said first and second polymeric sheath layers (24, 26) are formed from a single sheet, said sheet being folded in the middle to form an outer sheath.

13. A method for making a flat cell comprising the steps of:

(a) providing a first polymer jacket layer (24, 24'),

(b) providing a first current collector (18) and disposing it on the first polymer sheet (24),

(c) applying an anode material (12) to the first current collector (18),

(d) providing a second polymer sheet (26),

(e) providing a second current collector (20) formed of a metal foil and disposing it on the second polymeric sheet (26),

(f) providing a sealing frame (22) having an inner contour substantially corresponding to an outer contour of the anode material (12) and the separator (14) on the first current collector (18),

(g) arranging the frame (22) on one of the current collectors (20), the frame covering the outer periphery of the current collector (20),

(h) providing a cathode material (16) and disposing it on the second current collector (20),

(i) providing a separator layer (14) and disposing it on the cathode material (12),

(j) assembling the flat cell by inverting one of two polymer jacket layers (24; 26) and disposing it on the other polymer jacket layer (26; 24) such that the separator layer (14) is sandwiched between the cathode material (16) and the anode material (12), with the sealing frame (22) extending circumferentially around the anode material (12), cathode material (16), and separator (14), and

(k) the first and second polymeric sheath layers (24, 26) are sealed together over an area circumferentially extending beyond the current collectors (18, 20) to form an outer sheath of the battery package, wherein the polymeric sheath layers (24, 24 '; 26,26 ') are also sealed to the frame (22, 22 ') at an area circumferentially outward of the current collectors (18, 18 '; 20, 20 ').

14. The method of claim 13, wherein the sealing frame (22) is disposed on the second current collector (20) prior to performing step (h).

15. The method of claim 14, wherein the sealing frame (22) is composed of two sealing frame elements (22 a, 22 b), and wherein,

applying a first frame element (22 a) on the first current collector (18) before performing step (c), and

applying a second frame element (22 b) on the second current collector (20) before performing step (h), and

the two frame elements (22 a, 22 b) are joined together to form the frame (22) when step (k) is performed.

16. The method of claim 15, wherein each of the sealing frame elements (22 a, 22 b), the current collectors (18, 20) on which the sealing frame elements (22 a, 22 b) are disposed, and the polymer sheathing layers (24, 26) on which the current collectors (18, 20) are disposed, are respectively bonded to one another prior to performing steps (c) and (h).

17. The method of claim 16, wherein the sealing frame (22) is coated with a heat sealable material and is joined with the current collector (20) prior to performing step (j), wherein the sealing frame (22) is disposed on the current collector (20).