Eve Energy Co., Ltd v. Varta Microbattery Gmbh
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`Eve Ex. 1005, p. 1
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`

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`GALVANIC ELEMENT WITH NOVEL HOUSING
`
`
`Description
`
`[0001] The present invention relates to a galvanic element having a novel
`housing, and to a method for the production thereof.
`
`[0002] Galvanic elements, in particular those in the form of a button cell,
`typically have a housing made of a housing cup (often also referred to as a
`housing bowl) and a housing cover. The housing cup can, for example, be
`produced from nickel-plated deep-drawn sheet metal as a punched and drawn
`part. Usually, the housing cup is positively polarized and the housing cover is
`negatively polarized. Such galvanic elements can contain a wide variety of
`electrochemical systems, for example zinc/MnO2 or primary lithium systems,
`or else secondary systems, such as nickel/cadmium, nickel/metal hydride, or
`secondary lithium systems.
`
`[0003] The liquid-tight closure of such cells is usually effected by flanging the
`edge of the cup over the edge of the housing cover, wherein a plastic ring
`simultaneously serves as a sealing ring and for insulating the housing cup and
`the housing cover. Such button cells can be found in DE 31 13 309, for
`example.
`
`[0004] The sealing elements required for said button cells are typically
`produced by injection molding, for example from polyamides. The injection
`tools required for this purpose are expensive and costly to maintain. Moreover,
`it is practically impossible to produce sealing elements with walls having a
`thickness of less than 0.3 mm by injection molding. Seals produced in the
`injection molding process consequently take up a relatively large volume, and
`thus impair the capacity utilization of a cell, which can play a large role
`especially given button cells.
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`Eve Ex. 1005, p. 2
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`[0005] DE 196 47 593 describes the use of a sealing element which is
`produced from a film by deep drawing. A cup-shaped molded part is drawn
`from a heated film under vacuum by means of a drawing die and a forming
`punch. Polyamides are specified as the preferred film material. The
`deformation takes place in one or more stepped process steps depending on
`the desired diameter/height ratio. In the bottom region of the cup-shaped
`molded part produced by deep-drawing, a punching then takes place by
`means of a cutting punch and a cutting bush. The sealing element thus
`produced is mounted on a housing cover which can then be inserted into a
`housing cup. With the method described in DE 196 47 593, sealing elements
`that are up to 5 mm high with very uniform wall thicknesses can be produced
`depending on the selected process parameters. The thickness of the starting
`material is thereby preferably in the range between 0.1 mm and 0.3 mm. If, for
`example, a film with a thickness of 0.15 mm is used as the starting material, a
`wall thickness of approximately 0.12 mm can be achieved.
`
`[0006] The use of such a thin film seal increases the available internal volume
`of a galvanic cell of the aforementioned design, and thus facilitates a
`significantly improved capacity utilization.
`
`[0007] However, problems have arisen given use of conventional single-walled
`housing covers (prior art shown schematically in Fig. 1) in conjunction with
`sealing elements made of film. Conventional covers (1) are very unstable in
`the edge region. They have sharp cut edges at the edge (2) which, under
`disadvantageous circumstances, can cut through a film used as a sealing
`element (3). The contact surface of such covers is also very small, so that a
`partial penetration of the cover together with the film seal into the cathode is
`possible even with a slight amount of pressure.
`
`[0008] Housing covers having a double-walled housing casing formed by
`folding over the edge (see DE 196 47 593) are also known from the prior art.
`The use thereof is certainly capable of solving the mentioned problems
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`Eve Ex. 1005, p. 3
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`occurring in conjunction with film seals. The use of such housing covers
`ensures an increased stability, sharp edges do not occur in the edge region,
`and the support surface of such covers is also markedly increased with respect
`to the conventional housing cover.
`
`[0009] However, the use of double-walled housing covers has a negative effect
`on the available internal volume in a cell. Consequently, the capacity increase
`that can theoretically be achieved via the use of film seals is not achieved.
`
`[0010] The present invention is based upon the object of providing a galvanic
`cell of the type mentioned in the preamble, which is characterized by an
`optimized internal volume and thus an optimized capacity utilization, but at the
`same time thereby avoids an occurrence of the aforementioned problems.
`
`[0011] This object is achieved by the galvanic element having the features of
`claim 1. Preferred embodiments of the method according to the invention are
`shown in dependent claims 2 to 13. Claim 14 relates to a method for producing
`a galvanic element according to the invention. The wording of all claims is
`herewith rendered by reference to the content of this description.
`
`[0012] In a particularly preferred embodiment, a galvanic element according to
`the present invention is present as a button cell. It has a housing that
`comprises a housing cup with a cup base, and a substantially cylindrical cup
`casing, and a housing cover having a cover base and a circumferential,
`substantially cylindrical section. A film seal isolates the housing cup and the
`housing cover from one another. In the closed state of the housing, the
`cylindrical section of the housing cover abuts against the inner wall of the
`housing cup. An edge portion adjoins it. It is preferred that the latter is seated
`in the base region of the housing cup in the closed state of the housing.
`
`is particularly
`invention
`the
`to
`[0013] A galvanic element according
`characterized by its housing cover, which differs markedly from housing covers
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`Eve Ex. 1005, p. 4
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`known from the prior art. In the edge portion, the housing cover of a galvanic
`element according to the invention is folded over outwards and at the same
`time curved radially inwards.
`
`[0014] As a result of the housing cover being folded over, sharp cut edges
`which possibly occur at the edge of the housing cover are not perpendicular to
`the film seal. Instead, the housing cover of a galvanic element according to the
`invention has a rounded edge, which greatly reduces the risk of cutting through
`the film seal and additionally increases the contact surface of the housing
`cover in the base region of the housing cup.
`
`[0015] However, the mere folding over of the housing cover could lead to
`negative impacts on the internal cell volume, as are known from the prior art.
`Therefore, the housing cover of a galvanic cell according to the invention is
`folded over outwards only in the edge portion, and at the same time is curved
`radially inwards in this region. A wide, double-walled region, such as those that
`housing covers known from the prior art have, is not formed in the present
`instance. This results in the internal volume of the housing of a galvanic
`element according to the invention being restricted only in the (small) region
`of the curvature.
`
`[0016] The cylindrical section of the housing cover preferably has a
`substantially uniform outer diameter over its entire length, which is set to the
`corresponding inner diameter of the housing cup. In contrast thereto, the outer
`diameter of the housing cover in the edge portion is not constant along the
`edge portion as a result of the fold-over and of the radial inward curvature. The
`outer diameter of the housing cover in the edge portion preferably does not
`exceed the outer diameter of the cylindrical cover section at any point. In a
`particularly preferred embodiment of a galvanic element according to the
`invention, the maximum outer diameter of the housing cover in the edge
`portion corresponds substantially to the outer diameter of the substantially
`cylindrical cover portion. In this preferred embodiment, at least a part of the
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`Eve Ex. 1005, p. 5
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`housing cover can thus also abut annularly against the inner wall of the
`housing cup in the edge portion.
`
`[0017] It is preferred that less than 0.5 mm of the housing cover of a galvanic
`element according to the invention is folded over. The cover is particularly
`preferably only folded over by 0.1 mm to 0.35 mm, in particular only
`approximately 0.25 mm. These numbers further clarify the contrast to the prior
`art, from which are known only housing covers which have a double-walled
`region formed by folding over the edge, which region normally extends at least
`over half the height (several millimeters) of the housing cover.
`
`[0018] The film seal of a galvanic element according to the invention is formed
`in particular from a deep-drawn film. In principle, all common, deep-drawable
`plastics are considered, in particular also composites and sandwich structures
`made of several different plastics. The film seal is particularly preferably
`formed from a polyamide.
`
`[0019] In a further preferred embodiment, the film seal is formed from a high
`temperature-resistant film. Film seals made of a high-temperature-resistant
`film are particularly suitable for button cells used in the electronics sector.
`Circuit boards are thereby equipped with button cells as well as further (in
`particular electronic) components, and are wave-soldered or reflow-soldered.
`The button cells can thereby briefly heat up to temperatures of up to 250°C.
`Common seals made of polyethylene or of polyamides already soften at these
`temperatures and lose their shape. This results in leakages and leaking cells.
`
`[0020] In a particularly preferred embodiment, the film seal is therefore formed
`from polyether ether ketone (PEEK). Seals made of this material can be
`heated consistently to 250°C, even briefly to 300°C. Due to its flow properties,
`it is not possible to produce seals made of PEEK via injection molding.
`However, as a film it can be easily drawn to form a seal.
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`Eve Ex. 1005, p. 6
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`[0021] The production of the film seal of an element according to the invention
`preferably takes place as a molded part as described in DE 196 47 593. It is
`preferred that, after its production, the sealing molding thus produced is
`mounted on a housing cover which can then be inserted into a housing cup. In
`the closed state of the housing of a galvanic element according to the
`invention, the film seal is preferably arranged circumferentially on the housing
`cover, wherein it is thereby further preferred that it has an overlap in the edge
`region of the housing cover, said overlap pointing into the cell interior. The film
`seal preferably extends so far in the direction of the cover base that a direct
`contact between housing cup and housing cover is precluded upon flanging
`the housing cup.
`
`[0022] In a preferred embodiment, the film seal is shrunk onto the housing
`cover. The process of shrinking is also described in DE 196 47 593.
`
`[0023] Film seals are preferably used which have a thickness of between 0.01
`mm and 0.3 mm. Particularly preferred are film seals having a thickness of
`between 0.01 mm and 0.15 mm, in particular between 0.08 mm and 0.12 mm.
`
`[0024] In a preferred embodiment of a galvanic element according to the
`invention, a sealing compound is introduced in the edge portion of the housing
`cover between the film seal and the cover, in particular for sealing against
`creep effects. The sealing compound is preferably bitumen or a polyamide
`adhesive.
`
`[0025] The housing cup and the housing cover of a galvanic element according
`to the invention are preferably made of metal. In particular, nickel-plated deep-
`drawn sheet metal is thereby preferred as a metallic material.
`
`[0026] Due to its design in the edge portion, the housing cover of a galvanic
`element according to the invention has a surprisingly high degree of stability.
`Whereas conventional housing covers without a folded-over edge are very
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`Eve Ex. 1005, p. 7
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`unstable in the edge region and therefore, for stability reasons, can often only
`be installed as housing covers with walls that are relatively very thick, the
`housing covers of a galvanic element according to the invention can also be
`installed in very thin wall thicknesses.
`
`[0027] The housing cover of a galvanic element according to the invention
`particularly preferably has a wall thickness of between 0.08 mm and 0.2 mm,
`in particular between 0.1 mm and 0.15 mm.
`
`[0028] The housing cover of a galvanic element according to the invention has
`a particularly high degree of stability with respect to radial pressure in the edge
`portion. This stability advantageously opens up a possibility of further
`optimizing the sealing properties of the housing of a galvanic element
`according to the invention.
`
`[0029] A galvanic element according to the present invention is particularly
`preferred when the housing cup is indented radially inwards in the region of
`the cup base.
`
`[0030] By indenting the cup base, a radial pressure is generated on the edge
`portion of the housing cover that abuts against the inner wall of the housing
`cup. The film seal arranged between housing cup and housing cover is thereby
`compressed in this region, resulting in a markedly improved leakage behavior
`of a galvanic element according to the invention. The indenting can take place
`during or after the flanging of the housing cup following the assembly of the
`galvanic element.
`
`[0031] A galvanic element according to the invention preferably has, in the
`region of the indentation, an outer diameter reduced by 0.01 mm to 0.15 mm,
`preferably by 0.05 mm to 0.1 mm.
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`Eve Ex. 1005, p. 8
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`[0032] A method for producing a galvanic element according to the invention
`is also the subject matter of the present invention. A method according to the
`invention comprises the assembly of a galvanic element from a housing cup,
`a housing cover with an edge that is folded over outwards and curved radially
`inwards, a film seal, and the components involved in the electrochemical
`process (in particular the electrodes, the separator, and the electrolyte) as well
`as the flanging of the cell cup. It is characterized in that, during or after the
`flanging, the housing cup is indented radially inwards in the region of the cup
`base. The indentation thereby preferably takes place by means of a calibration
`bushing.
`
`[0033] The process of indenting the housing cup has already been addressed.
`The housing components (housing cup, housing cover, and film seal) to be
`used in the method according to the invention have also already been
`explained in detail above. Reference is hereby made to the corresponding
`passages of the description, which are expressly referenced.
`
`[0034] The cited and further advantages of the invention result from the
`description of the following examples and drawings in conjunction with the
`dependent claims. The individual features of the invention can thereby be
`realized alone or in combination with one another. The described embodiments
`serve merely for explanation and for a better understanding of the invention,
`and are not to be understood as limiting in any way.
`
`DESCRIPTION OF FIGURES
`
`[0035] The drawings show:
`
`[0036] Fig. 1: Cross section of a conventional housing cover with a film seal
`according to the prior art (partial view).
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`Eve Ex. 1005, p. 9
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`[0037] Fig. 2: Partial view of the housing of a preferred embodiment of a
`galvanic element according to the invention (cross section)
`
`[0038] Fig. 3: Cross section of the housing cover of the housing shown in Fig.
`2
`
`[0039] Fig. 4: Partial view (edge portion of the housing cover) of a preferred
`embodiment of a galvanic element according to the invention (cross section)
`
`[0040] Fig. 5: Partial view (in particular the base region of the housing cup) of
`the housing of a preferred embodiment of a galvanic element according to the
`invention (cross section)
`
`[0041] Fig. 6: Schematic representation of the production of a fully assembled
`component made of housing cover and film seal, with additionally introduced
`sealing compound in the edge portion of the housing cover. All components
`are shown in detail in cross section.
`
`[0042] Fig. 1 has already been explained in conjunction with the discussion of
`the prior art.
`
`[0043] Fig. 2 shows in cross section the partial view of the housing 100 of a
`preferred embodiment of a galvanic element according to the invention. The
`housing has a housing cover 101 and a housing cup 102. Arranged between
`the housing cover and the housing cup is a film seal 103, which is guided
`around the rounded edge of the housing cover in the lower region of the
`housing and slightly overlaps into the cell interior. The housing cup has a cup
`base 105 and a substantially cylindrical cup casing 106 which is flanged in the
`upper region. In the bottom region, the housing cup has a slight indentation
`104.
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`Eve Ex. 1005, p. 10
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`[0044] Fig. 3 shows the cross section of the housing cover 101 from Fig. 1.
`The cover can be divided roughly into three regions, namely the cover base
`201, the substantially cylindrical portion 202, and the edge portion 203
`adjoining thereto. The cover base has a planar central portion 206 and a bent-
`down edge 207. The edge portion is additionally shown enlarged as an
`interesting aspect. Clearly visible are the folded-over cut edge 204, the
`rounded edge of the cover 205 and, in particular, also the curvature/backward
`curvature of the housing cover.
`
`[0045] Fig. 4 shows in cross section a partial view (edge portion of the housing
`cover) of the housing of a preferred embodiment of a galvanic element
`according to the invention. In the edge portion, a sealing compound 301 is
`introduced between the film seal and the cover.
`
`[0046] Fig. 5 also shows a cross-sectional view of a partial view of the housing
`of a preferred embodiment of a galvanic element according to the invention.
`The focus here is on the base region of the housing cup, which has an indented
`region 401. In this region, the housing cup has a smaller outer diameter than
`in the upper region 403 of the cup casing. The edge 402 forms the transition
`between the two regions. Visible on the inside of the housing cup are the
`housing cover and the film seal arranged between housing cover and housing
`cup, which film seal is pressed on the edge portion of the housing cover due
`to the radial pressure caused by the indentation.
`
`[0047] The production of a housing cover provided with a film seal is
`schematically illustrated in Fig. 6. In (1), a film seal 103 is provided as a deep-
`drawn molded part with an inwardly formed protrusion at the lower end. In (2),
`the protrusion is affected with sealing mass 301. The application of the film
`seal 103 to a housing cover 101 is shown in (3). (4) illustrates a fully assembled
`component composed of housing cover 101 and film seal 103, with edge
`portion 203 sealed by sealing material 301.
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`Eve Ex. 1005, p. 11
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`Example 1
`
`[0048] A cell with a conventional structure has a housing with a housing cup
`having a wall thickness of 0.1-0.2 mm, a film seal having a thickness of 0.03-
`0.05 mm, and a housing cover having a thickness of 0.1-0.2 mm. This results
`in a total structural thickness of 0.23-0.45 mm. However, the housing cover
`proves to be too unstable at the edge. Due to the folding, according to the
`invention, of the housing cover in the edge region over a length of 0.25 mm, a
`doubling of the thickness of the cover is achieved in the edge region. The
`housing cover is subsequently calibrated to the external dimension in the edge
`region. The cover thus reinforced meets the mechanical requirements
`significantly better. A cutting of the film seal as well as a damage to the cathode
`were reliably avoided.
`
`Example 2
`
`[0049] A cell according to the invention according to Example 1 was indented
`by 0.05-0.1 mm in diameter after flanging in the base region over a length of
`0.4 mm. The inner side of the housing cup was thereby pressed against the
`stable edge of the cover over the film seal. The samples thus produced have
`a markedly improved leakage behavior.
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`Eve Ex. 1005, p. 12
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`

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`Claims
`
`Galvanic element, in particular button cell, having a housing (100),
`1.
`comprising
`– a housing cup (102) having a cup base (105) and a substantially
`cylindrical cup casing (106),
`– a housing cover (101) having a cover base (201), a circumferential,
`substantially cylindrical portion (202) which abuts against the inner wall of the
`housing cup in the closed state of the housing, and an edge portion (203)
`adjoining thereto, and
`– a film seal (103) which isolates the housing cup and the housing cover
`from one another,
`wherein the housing cover (101) is folded over outwards and curved
`radially inwards in the edge portion (203).
`
`The galvanic element according to claim 1, characterized in that the
`2.
`housing cover (101) has, in the edge portion (203), a maximum outer diameter
`which substantially corresponds to the outer diameter of the substantially
`cylindrical cover portion (202).
`
`The galvanic element according to claim 1 or claim 2, characterized in
`3.
`that the housing cover (101) is folded over by less than 0.5 mm, preferably
`between 0.1 mm and 0.35 mm, in particular by approximately 0.25 mm.
`
`The galvanic element according to any one of claims 1 to 3,
`4.
`characterized in that the film seal (103) is formed from a deep-drawable film.
`
`The galvanic element according any one of the preceding claims,
`5.
`characterized in that the film seal (103) is formed from a polyamide.
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`Eve Ex. 1005, p. 13
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`The galvanic element according to any one of claims 1 through 4,
`6.
`characterized in that the film seal (103) is formed from a high temperature-
`resistant film.
`
`The galvanic element according to claim 6, characterized in that the film
`7.
`seal (103) is formed from polyether ether ketone.
`
`The galvanic element according to any one of the preceding claims,
`8.
`characterized in that the film seal (103) has a thickness of between 0.01 mm
`and 0.3 mm, preferably between 0.01 mm and 0.15 mm, in particular between
`0.03 mm and 0.05 mm.
`
`The galvanic element according to any one of the preceding claims,
`9.
`characterized in that a sealing compound (301) is introduced in the edge
`portion (203) of the housing cover (101), between film seal (103) and housing
`cover (101).
`
`The galvanic element according to any one of the preceding claims,
`10.
`characterized in that the housing cup (102) and the housing cover (101) are
`produced from metal, in particular from nickel-plated deep-drawn sheet metal.
`
`The galvanic element according to any one of the preceding claims,
`11.
`characterized in that the housing cover (101) has a wall thickness between
`0.08 mm and 0.2 mm, in particular between 0.08 mm and 0.13 mm.
`
`The galvanic element according to any one of the preceding claims,
`12.
`characterized in that the housing cup (102) is indented radially inwards in the
`region of the cup base (401).
`
`The galvanic element according to claim 12, characterized in that the
`13.
`housing cup (102) has an outer diameter that is reduced by 0.01 mm to 0.15
`mm, preferably by 0.05 mm to 0.1 mm, in the region of the indentation.
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`Eve Ex. 1005, p. 14
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`
`14. Method for producing a galvanic element according to any one of the
`preceding claims, comprising the assembly of the element from a housing cup
`(102), a housing cover (101) having an edge portion (203) that is folded over
`outwards and curved radially inwards, a film seal (103), and the components
`involved in the electrochemical process, as well as the flanging of the housing
`cup (102) over the edge of the cover base (201), wherein the housing cup
`(102) is indented in the region of the cup base (105) during or after flanging.
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`Eve Ex. 1005, p. 15
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`Abstract
`
`The present invention relates to a galvanic element, in particular a button cell,
`having a housing (100), comprising
`
`a housing cup (102) having a cup base (105) and a substantially
`-
`cylindrical cup casing (106),
`-
`a housing cover (101) having a cover base (201), a circumferential,
`substantially cylindrical portion (202) which abuts against the inner wall of the
`housing cup in the closed state of the housing, and an edge portion (203)
`adjoining thereto, and
`-
`a film seal (103) which isolates the housing cup and the housing cover
`from one another,
`
`wherein the housing cover (101) is folded outwards and curved radially
`inwards in the edge portion (203).
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`Eve Ex. 1005, p. 16
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`Eve Ex. 1005, p. 17
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`Eve Ex. 1005, p. 18
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`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
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`Eve Ex. 1005, p. 19
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`

`

`*DE102005058132A120070606*
`
`(19)
`Bundesrepublik Deutschland
`Deutsches Patent- und Markenamt
`
`(10) DE 10 2005 058 132 A1 2007.06.06
`
`
`(12)
`
`Offenlegungsschrift
`
`(21) Aktenzeichen: 10 2005 058 132.3
`(22) Anmeldetag: 30.11.2005
`(43) Offenlegungstag: 06.06.2007
`
`(51) Int Cl.8: H01M 2/02 (2006.01)
`
`(71) Anmelder:
`VARTA Microbattery GmbH, 30419 Hannover, DE
`
`(74) Vertreter:
`Patentanwälte Ruff, Wilhelm, Beier, Dauster &
`Partner, 70174 Stuttgart
`
`(56) Für die Beurteilung der Patentfähigkeit in Betracht zu
`ziehende Druckschriften:
`DE 196 47 593 A1
`DE 31 32 548 A1
`DE 31 13 309 A1
`DE 696 02 122 T2
`
`(72) Erfinder:
`Brenner, Rolf, 73479 Ellwangen, DE; Kreidler,
`Bernd, 73479 Ellwangen, DE; Ilic, Dejan, Dr., 73479
`Ellwangen, DE; Holl, Konrad, Dr., 73434 Aalen, DE;
`Ernsperger, Jürgen, 73491 Neuler, DE
`
`Die folgenden Angaben sind den vom Anmelder eingereichten Unterlagen entnommen
`
`Rechercheantrag gemäß § 43 Abs. 1 Satz 1 PatG ist gestellt.
`
`(54) Bezeichnung: Galvanisches Element mit neuartigem Gehäuse
`
`(57) Zusammenfassung: Die vorliegende Erfindung betrifft
`ein galvanisches Element, insbesondere Knopfzelle, mit ei-
`nem Gehäuse (100), umfassend
`- einen Gehäusebecher (102) mit einem Becherboden
`(105) und einem im wesentlichen zylindrisch ausgebildeten
`Bechermantel (106),
`- einen Gehäusedeckel (101) mit einem Deckelboden
`(201), einem umlaufenden, im verschlossenen Zustand
`des Gehäuses an der Innenwand des Gehäusebechers an-
`liegenden, im wesentlichen zylindrisch ausgebildeten Ab-
`schnitt (202) und einem sich daran anschließenden
`Randabschnitt (203) und
`- eine Foliendichtung (103), die den Gehäusebecher und
`den Gehäusedeckel gegeneinander isoliert,
`wobei der Gehäusedeckel (101) im Randabschnitt (203)
`nach außen umgeschlagen und radial nach innen gewölbt
`ist.
`
`1/13
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1005, p. 20
`
`

`

`DE 10 2005 058 132 A1 2007.06.06
`
`Beschreibung
`
`[0001] Die vorliegende Erfindung betrifft ein galvani-
`sches Element mit einem neuartigen Gehäuse und
`ein Verfahren zu dessen Herstellung.
`
`[0002] Galvanische Elemente, insbesondere solche
`in Knopfzellenform, weisen üblicherweise ein Gehäu-
`se aus einem Gehäusebecher (oft auch als Gehäu-
`senapf bezeichnet) und einem Gehäusedeckel auf.
`Der Gehäusebecher kann beispielsweise aus verni-
`ckeltem Tiefziehblech als Stanzziehteil hergestellt
`werden. Gewöhnlich ist der Gehäusebecher positiv
`und der Gehäusedeckel negativ gepolt. Derartige
`galvanische Elemente können die verschiedensten
`elektrochemischen Systeme enthalten, beispielswei-
`se Zink/MnO2 oder primäre Lithium-Systeme oder
`auch sekundäre Systeme wie Nickel/Cadmium, Ni-
`ckel/Metallhydrid oder sekundäre Lithium-Systeme.
`
`[0003] Der flüssigkeitsdichte Verschluß solcher Zel-
`len erfolgt gewöhnlich durch Umbördeln des Becher-
`randes über den Rand des Gehäusedeckels, wobei
`ein Kunststoffring gleichzeitig als Dichtring sowie zur
`Isolierung des Gehäusebechers und des Gehäuse-
`deckels dient. Derartige Knopfzellen sind beispiels-
`weise der DE 31 13 309 zu entnehmen.
`
`[0004] Die für diese Knopfzellen erforderlichen
`Dichtungselemente werden üblicherweise im Spritz-
`gießverfahren, beispielsweise aus Polyamiden her-
`gestellt. Die dazu notwendigen Spritzwerkzeuge sind
`teuer und aufwendig zu warten. Darüber hinaus ist es
`praktisch nicht möglich, durch Spritzguß Dichtungse-
`lemente mit Wandungen in einer Dicke von weniger
`als 0,3 mm herzustellen. Im Spritzgießverfahren her-
`gestellte Dichtungen beanspruchen folglich ein ver-
`hältnismäßig großes Volumen und beeinträchtigen
`damit die Kapazitätsausnutzung einer Zelle, was ins-
`besondere bei Knopfzellen eine große Rolle spielen
`kann.
`
`[0005]
`In der DE 196 47 593 wird der Einsatz eines
`Dichtungselements beschrieben, das durch Tiefzie-
`hen aus einer Folie hergestellt wird. Aus einer be-
`heizten Folie wird mittels einer Ziehmatrize und eines
`Formstempels unter Vakuum ein becherförmiges
`Formteil gezogen. Als bevorzugtes Folienmaterial
`werden Polyamide angegeben. Die Verformung er-
`folgt abhängig vom gewünschten Durchmesser/Hö-
`hen-Verhältnis in einem oder mehreren abgestuften
`Arbeitsgängen. Im Bodenbereich des durch Tiefzie-
`hen hergestellten becherförmigen Formteils erfolgt
`anschließend eine Ausstanzung mittels eines
`Schnittstempels und einer Schnittbuchse. Das so
`hergestellte Dichtungselement wird auf einen Gehäu-
`sedeckel montiert, der dann in einen Gehäusebecher
`eingesetzt werden kann. In Abhängigkeit der gewähl-
`ten Verfahrensparameter lassen sich mit dem in der
`DE 196 47 593 beschriebenen Verfahren bis zu 5 mm
`
`hohe Dichtungselemente mit sehr gleichmäßigen
`Wandstärken herstellen. Die Dicke des Ausgangs-
`materials liegt dabei vorzugsweise im Bereich zwi-
`schen 0,1 mm und 0,3 mm. Wenn beispielsweise
`eine Folie mit einer Stärke von 0,15 mm als Aus-
`gangsmaterial verwendet wird, ist eine Wandstärke
`von ca. 0,12 mm erzielbar.
`
`[0006] Die Verwendung einer solch dünnen Folien-
`dichtung vergrößert das zur Verfügung stehende In-
`nenvolumen einer galvanischen Zelle der oben ge-
`nannten Bauart und ermöglicht somit eine deutlich
`verbesserte Kapazitätsausnutzung.
`
`[0007] Bei Verwendung herkömmlicher einwandiger
`Gehäusedeckel (schematisch in Fig. 1 dargestellter
`Stand der Technik) in Verbindung mit Dichtungsele-
`menten aus Folien haben sich allerdings Probleme
`ergeben. Herkömmliche Deckel (1) sind gerade im
`Randbereich sehr labil. Sie weisen am Rand (2)
`scharfe Schnittkanten auf, die unter ungünstigen Um-
`ständen eine als Dichtungselement (3) verwendete
`Folie durchschneiden können. Auch ist die Auflage-
`fläche solcher Deckel sehr gering, so daß gegebe-
`nenfalls schon bei geringem Druck ein teilweises Ein-
`dringen des Deckels mitsamt Foliendichtung in die
`Kathode möglich ist.
`
`[0008] Aus dem Stand der Technik sind auch Ge-
`häusedeckel mit durch Umschlagen des Randes ge-
`bildetem doppelwandigem Gehäusemantel bekannt
`(siehe DE 196 47 593). Deren Verwendung vermag
`die angesprochenen, in Verbindung mit Foliendich-
`tungen auftretenden Probleme durchaus zu lösen.
`Der Einsatz solcher Gehäusedeckel gewährleistet
`eine erhöhte Stabilität, scharfe Kanten im Randbe-
`reich treten nicht auf, und auch die Auflagefläche sol-
`cher Deckel ist gegenüber der herkömmlicher Ge-
`häusedeckel deutlich erhöht.
`
`[0009] Allerdings wirkt sich die