`
`111111111111111111111111111!11191161111111,1111111111111111111111111
`
`(12) United States Patent
`Pytlik et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 9,496,581 B2
`*Nov. 15, 2016
`
`(54) BUTTON CELLS AND METHOD OF
`PRODUCING SAME
`
`(71) Applicant: VARTA Microbattery GmbH,
`Ellwangen (DE)
`
`(72)
`
`Inventors: Eduard Pytlik, Ellwangen (DE);
`Jurgen Lindner, Ellwangen (DE);
`Ulrich Barenthin, Ellwangen (DE);
`Winfried Gaugler, Ellwangen (DE)
`
`(73) Assignee: Varta Microbattery GmbH (DE)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`This patent is subject to a terminal dis-
`claimer.
`
`(21) Appl. No.: 14/827,387
`
`(22) Filed:
`
`Aug. 17, 2015
`
`(65)
`
`Prior Publication Data
`
`US 2015/0372339 Al
`
`Dec. 24, 2015
`
`Related U.S. Application Data
`
`(62) Division of application No. 13/146,669, filed as
`application No. PCT/EP2010/000787 on Feb. 9,
`2010, now Pat. No. 9,153,835.
`
`(30)
`
`Foreign Application Priority Data
`
`Feb. 9, 2009
`Jun. 18, 2009
`Dec. 22, 2009
`
`(DE)
`(DE)
`(DE)
`
`10 2009 008 859
`10 2009 030 359
`10 2009 060 788
`
`(51) Int. Cl.
`HO1M 4/00
`HO1M 6/10
`
`(2006.01)
`(2006.01)
`(Continued)
`
`(52) U.S. Cl.
`CPC
`
`HO1M 10/0431 (2013.01); HO1M 2/0222
`(2013.01); HO1M 6/10 (2013.01);
`
`(58) Field of Classification Search
`CPC .. HO1M 2/0222; HO1M 2/0207; HO1M 4/70;
`HO1M 4/76
` 429/94, 162, 164, 171, 172
`USPC
`See application file for complete search history.
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,960,599 A
`4,220,695 A
`
`6/1976 Reynier et al.
`9/1980 Ishida et al.
`(Continued)
`
`FOREIGN PATENT DOCUMENTS
`
`CN
`DE
`
`4/2010
`201440429
`5/1969
`1 471 758 Al
`(Continued)
`
`OTHER PUBLICATIONS
`
`US Official Action dated Aug. 29, 2014 from related U.S. Appl. No.
`13/378,117.
`
`Primary Examiner — Patrick Ryan
`Assistant Examiner — Julian Anthony
`(74) Attorney, Agent, or Firm — DLA Piper LLP (US)
`
`(57)
`
`ABSTRACT
`
`A button cell includes a housing cup and a housing top
`separated from one another by an insulating seal and which
`form a housing with a flat bottom and a flat top parallel to
`it, and an electrode-separator assembly within the housing
`including flat layer positive and negative electrodes and
`connected to one another by a flat separator, wherein the
`layers are aligned essentially at right angles to the flat
`bottom and the flat top and the electrode-separator assembly
`is a spiral winding having end faces defining side surfaces of
`the spiral winding facing in an axial direction relative to the
`flat bottom and the flat top, and one of the electrodes
`connects to the flat bottom or the flat top via an output
`conductor including a thin film resting flat between an end
`face of the spiral winding and the flat top or the flat bottom.
`
`(Continued)
`
`13 Claims, 3 Drawing Sheets
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`106
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`104
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`102
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`108
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`100
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`110
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`17,
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`101
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`•
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`• • • •
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`••
`• • •
`•
`
`///
`
`/1.
`.4/
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`109
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`107
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`105
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`103
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`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 1
`
`
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`US 9,496,581 B2
`Page 2
`
`Int. Cl.
`HO1M 6/12
`HO1M 6/46
`HO1M 2/02
`HO1M 6/08
`HOLM 10/04
`HOLM 10/05
`HOLM 10/24
`HO1M 10/34
`U.S. Cl.
`CPC
`
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`(2010.01)
`(2006.01)
`(2006.01)
`
` H01M10/0427 (2013.01); HO1M 10/05
`(2013.01); HO1M 10/24 (2013.01); HO1M
`10/34 (2013.01); Y02E 60/124 (2013.01);
`Y02P 70/54 (2015.11); YlOT 29/4911
`(2015.01); YlOT 29/49108 (2015.01)
`
`(56)
`
`References Cited
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`FOREIGN PATENT DOCUMENTS
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`DE
`DE
`DE
`DE
`DE
`DE
`DE
`DE
`EP
`EP
`EP
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`GB
`GB
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`JP
`WO
`
`10
`10
`10
`
`31 13 309 Al
`36 38 793 Al
`196 47 593 Al
`697 00 312 T2
`198 57 638 Al
`2009 008 859 Al
`2009 017 514 Al
`2009 017 515 Al
`0 202 857 B1
`1 372 209 Al
`1 808 916 Al
`1 968 134 Al
`1088271 A
`2 110 464
`01-307176 A
`H05-121056
`07-153488 A
`08-293299
`08-293299 A
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`2003-031266 A
`2004-158318 A
`3902330 B2
`2007-200683
`2007-294111 A
`2008-251192 A
`2008-262825 A
`2008-262826 A
`2010/089152 Al
`
`10/1982
`5/1988
`5/1998
`2/2000
`6/2000
`8/2010
`10/2010
`10/2010
`7/1991
`12/2003
`7/2007
`9/2008
`10/1967
`6/1983
`12/1989
`5/1993
`6/1995
`11/1996
`11/1996
`3/2000
`12/2002
`1/2003
`6/2004
`4/2007
`8/2007
`11/2007
`10/2008
`10/2008
`10/2008
`8/2010
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 2
`
`
`
`U.S. Patent
`
`Nov. 15, 2016
`
`Sheet 1 of 3
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`US 9,496,581 B2
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`106
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`104
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`102
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`108
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`101
`
`100
`
`110
`
`109
`
`107
`
`103
`
`105
`
`Fig. 1
`
`200 \\I\
`
`203
`
`/
`
`202
`
`201
`
`204
`
`250°C
`
`205
`
`I
`
`250°C
`
`Fig. 2
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 3
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`
`
`U.S. Patent
`
`Nov. 15, 2016
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`Sheet 2 of 3
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`US 9,496,581 B2
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`301
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`300
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`/
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`303
`302
`304
`305
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`301
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`Fig. 3A
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`302
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`303
`304
`305
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`306
`
`Fig. 36
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 4
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`
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`U.S. Patent
`
`Nov. 15, 2016
`
`Sheet 3 of 3
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`US 9,496,581 B2
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`410
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`402
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`403
`404
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`401-
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`400
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`401
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`407
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`406
`405
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`413
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`409
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`412
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`dig. 4
`
`50
`
`50$
`
`508
`4,09.riiroWnProLdn," Acirgroworww~ourit
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`
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`
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`
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`
`Fig. 5
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 5
`
`
`
`1
`BUTTON CELLS AND METHOD OF
`PRODUCING SAME
`
`US 9,496,581 B2
`
`RELATED APPLICATIONS
`
`This is a divisional of U.S. Ser. No. 13/146,669, filed Jul.
`28, 2011, which is a §371 of International Application No.
`PCT/EP2010/000787, with an international filing date of
`Feb. 9, 2010 (WO 2010/089152 Al, published Aug. 12,
`2010), which is based on German Patent Application Nos.
`10 2009 008 859.8, filed Feb. 9, 2009, 10 2009 030 359.6,
`filed Jun. 18, 2009, and 10 2009 060 788.9, filed Dec. 22,
`2009.
`
`TECHNICAL FIELD
`
`This disclosure relates to button cells comprising two
`metallic housing half-parts separated from one another by an
`electrically insulating seal and which form a housing with a
`flat bottom area and a flat top area parallel to it, as well as
`within the housing, an electrode-separator assembly com-
`prising at least one positive and at least one negative
`electrode, which are in the form of flat layers and are
`connected to one another by at least one flat separator, and
`to a method of producing such button cells.
`
`BACKGROUND
`
`Button cells normally have a housing consisting of two
`housing half-parts, a cell cup and a cell top. By way of
`example, these may be produced from nickel-plated deep-
`drawn metal sheet as stamped and drawn parts. The cell cup
`normally has positive polarity, and the housing top negative
`polarity. The housing may contain widely differing electro-
`chemical systems, for example, zinc/MnO2, primary and
`secondary lithium systems, or secondary systems such as
`nickel/cadmium or nickel/metal hydride.
`By way of example, rechargeable button cells based on
`nickel/metal hydride or lithium-ion systems are in wide-
`spread use. In the case of lithium-ion button cells, the
`electrochemically active materials are normally not arranged
`within the button cell housing in the form of individual
`electrodes, in the form of tablets, separated from one another
`by a separator. Instead, prefabricated electrode-separator
`assemblies are preferably inserted flat into the housing. In
`that case, a porous plastic film is preferably used as a
`separator, onto which the electrodes are laminated or adhe-
`sively bonded flat. The entire assembly comprising the
`separator and the electrodes generally have a maximum
`thickness of a few hundred pm. To allow button cell hous-
`ings of normal dimensions to be filled, a plurality of such
`assemblies are therefore frequently placed flat one on top of
`the other. This allows stacks of any desired height, in
`principle, to be produced, in each case matched to the
`available dimensions of the button cell housing into which
`the stack is intended to be installed. This ensures optimum
`utilization of the available area within the housing.
`By virtue of the design, however, various problems also
`occur in the case of button cells which contain such stacks
`of electrode-separator assemblies. On the one hand, it is
`necessary, of course, for the electrodes of the same polarity
`each to be connected to one another within the stack, and
`then each to make contact with the corresponding pole of the
`button cell housing. The required electrical contacts result in
`material costs, and the space occupied by them is, further-
`more, no longer available for active material. In addition, the
`production of the electrode stacks is complicated and expen-
`
`5
`
`2
`sive since faults can easily occur when the assemblies make
`contact with one another, increasing the scrap rate. On the
`other hand, it has been found that button cells having a stack
`of electrodes and separators very quickly start to leak.
`Traditionally, button cells have been closed in a liquid-
`tight manner by beading the edge of the cell cup over the
`edge of the cell top in conjunction with a plastic ring, which
`is arranged between the cell cup and the cell top and at the
`same time acts as a sealing element and for electrical
`10 insulation of the cell cup and of the cell top. Button cells
`such as these are described, for example, in DE 31 13 309.
`However, alternatively, it is also possible to manufacture
`button cells in which the cell cup and the cell top are held
`together in the axial direction exclusively by a force-fitting
`15 connection, and which do not have a beaded-over cup edge.
`Button cells such as these and methods for their production
`are described in German Patent Application 10 2009 017
`514. Irrespective of the various advantages which button
`cells such as these without beading may have, they can,
`20 however, not be loaded as heavily in the axial direction as
`comparable button cells with a beaded-over cup edge, in
`particular with respect to axial mechanical loads which are
`caused in the interior of the button cell. For example, the
`electrodes of rechargeable lithium-ion systems are continu-
`25 ally subject to volume changes during charging and dis-
`charging processes. The axial forces which occur in this case
`can, of course, lead to leaks more readily in the case of
`button cells without beading than in the case of button cells
`with beading.
`It could therefore be helpful to provide a button cell in
`which the problems mentioned above do not occur, or occur
`only to a greatly reduced extent. In particular, it could be
`helpful to provide a button cell that is resistant to mechanical
`loads which occur in the axial direction than conventional
`35 button cells, in particular even when they are manufactured
`as button cells without a beaded-over cup edge.
`
`30
`
`SUMMARY
`
`40 We provide a button cell including a housing cup and a
`housing top separated from one another by an electrically
`insulating seal and which form a housing with a flat bottom
`area and a flat top area parallel to it, and an electrode-
`separator assembly within the housing including at least one
`45 positive and at least one negative electrode in the form of flat
`layers and connected to one another by at least one flat
`separator, wherein the electrode layers are aligned essen-
`tially at right angles to the flat bottom and top areas and the
`button cell is closed without being beaded over.
`50 We also provide a method of producing the button cell
`including inserting an electrode-separator assembly with
`electrodes in the form of a flat layer into the housing such
`that the electrode layers are aligned essentially at right
`angles to the flat bottom and top areas, wherein the housing
`55 includes a metallic cup part and a metallic top part.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 schematically illustrates the cross section through
`60 one preferred example of a button cell.
`FIG. 2 illustrates the effect of heat treatment of a wound-
`up electrode-separator assembly, which is used in preferred
`examples of our method.
`FIGS. 3A and 3B show an electrode-separator assembly
`65 in the form of a winding, as can be installed in a button cell.
`FIG. 4 shows a section illustration of a further preferred
`example of a button cell.
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 6
`
`
`
`US 9,496,581 B2
`
`3
`FIG. 5 schematically illustrates the cross section through
`one preferred example of a button cell in which the edge of
`the cell cup is not beaded over the edge of the cell cop.
`
`DETAILED DESCRIPTION
`
`Our button cell comprises two metallic housing half-parts
`separated from one another by an electrically insulating seal
`and form a housing with a flat bottom area and a flat top area
`parallel to it. As already mentioned initially, the two housing
`half-parts are generally a so-called "housing cup" and a
`"housing top." In particular, parts composed of nickel-plated
`steel or metal sheet are preferred as housing half-parts.
`Furthermore, trimetals, for example, with the sequence of
`nickel, steel (or stainless steel) and copper (with the nickel
`layer preferably forming the outer layer and the copper layer
`preferably forming the inside of the button cell housing) are
`particularly suitable for use as the metallic material.
`By way of example, an injection-molded or film seal can
`be used as a seal. The latter are described, for example, in
`DE 196 47 593.
`Within the housing, a button cell comprises an electric-
`separator assembly with at least one positive and at least one
`negative electrode. These are each in the form of flat
`electrode layers. The electrodes are connected to one another
`via a flat separator. The electrodes are preferably laminated
`or adhesively bonded onto this separator. The electrodes and
`the separator generally each have thicknesses only in the pm
`range. In general, a porous plastic film is used as the
`separator.
`In contrast to the button cells mentioned initially, our
`button cell is distinguished in particular by the electrode
`layers having a very particular orientation, specifically being
`aligned essentially at right angles to the flat bottom and top
`areas. While button cells known from the prior art with
`stacked electrode-separator assemblies always contain these
`assemblies inserted flat such that the electrode layers are
`aligned essentially parallel to the flat bottom and top areas,
`the situation in our button cell is the opposite of this.
`The right-angled alignment of the electrode layers has an
`unexpectedly considerable advantage, specifically because it
`has been found that this alignment results in a considerable
`improvement in the sealing characteristics of our button cell,
`particularly for button cells based on lithium-ion systems.
`The electrodes of rechargeable lithium-ion systems are
`continually subject to volume changes during charging and
`discharging processes. Volume changes such as these also
`occur, of course, in the electrodes of our button cell. How-
`ever, the mechanical forces which are created during this
`process no longer act primarily axially, as in the case of a
`stack of electrode-separator assemblies which are inserted
`flat. Because of the right-angled alignment of the electrodes,
`they in fact act radially. Radial forces can be absorbed very
`much better than axial forces by the housing of a button cell.
`The improved sealing characteristics are presumably a result
`of this.
`Particularly preferably, the electrodes and the flat sepa-
`rator of our button cell are each in the form of strips or
`ribbons. By way of example, the production of our button
`cell can be based on a separator material in the form of an
`endless ribbon, onto which the electrodes are applied, in
`particular laminated, once again in particular in the form of
`strips or at least rectangles.
`In the housing of our button cell, this assembly is par-
`ticularly preferably in the form of a winding, in particular in
`the form of a spiral winding. Windings such as these can be
`produced very easily using known methods (see, for
`
`4
`example, DE 36 38 793), by applying the electrodes flat, in
`particular in the form of strips, to a separator which is in the
`form of an endless ribbon, in particular by laminating them
`on. In this case, the assembly comprising electrodes and
`5 separators is generally wound onto a so-called "winding
`mandrel." Once the winding has been removed from the
`winding mandrel an axial cavity remains in the center of the
`winding. This allows the winding to expand into this cavity,
`if necessary. However, in some circumstances, this can lead
`10 to problems in making electrical contact between the elec-
`trodes and the metallic housing half-parts, and this will be
`described in more detail in the following text.
`The electrode winding is preferably arranged within a
`15 button cell (so that the electrode layers of the winding are
`aligned at right angles to the flat bottom area and top area of
`the housing) such that the end faces of the winding face in
`the direction of the flat bottom area and of the flat top area.
`Preferably, our button cells have a fixed winding core in
`20 the center of the winding, which at least partially fills the
`axial cavity in the center of the winding. A winding core
`such as this fixes the electrode winding in the radial direction
`and prevents possible implosion of the winding into the axial
`cavity. When the winding expands in this way, this also
`25 results in the reduction in the pressure which the end faces
`of the winding exert in the axial direction, and therefore in
`the direction of output conductors which may be arranged
`there (this is described in more detail further below). If this
`is prevented, then there are generally also no problems with
`30 making electrical contact between the electrodes and the
`metallic housing half-parts.
`In addition, a winding core such as this also makes the
`button cell more robust against external mechanical influ-
`ences. In general, it is no longer possible for the electrode
`35 winding in the button cell to be damaged by external
`mechanical pressure in the axial direction.
`Preferably, the electrode winding is a spiral electrode
`winding, the axial cavity which has been mentioned in the
`center of the winding is preferably essentially cylindrical (in
`40 particular circular-cylindrical). On the casing side, it is
`bounded by the winding, and at the end it is bounded by
`corresponding surfaces of the bottom area and of the top area
`of the button cell housing.
`Correspondingly, the winding core which is contained in
`45 our button cell is preferably also in the form of a cylinder,
`in particular a hollow cylinder. The height of a cylinder such
`as this preferably corresponds to the respective distance
`between the flat bottom area and the flat top area, which is
`parallel to it.
`Particularly preferably, the winding core may have radi-
`ally self-expanding characteristics. For example, it is pos-
`sible for the winding core to be inserted in a radially
`compressed configuration into the axial cavity in the wind-
`ing of a button cell. When the radially compressed winding
`55 core expands, it exerts a radial pressure on the electrode
`winding surrounding it, thus ensuring a contact pressure in
`the axial direction as well.
`By way of example, an axially slotted hollow cylinder
`may be used as a radially self-expanding winding core.
`60 However, alternatively, it is also conceivable to use other
`radially self-expanding materials, for example, based on
`plastic.
`Particularly preferably, the winding core is composed of
`a metal such as stainless steel or plastic.
`Particularly preferably, the assembly comprising elec-
`trodes and a separator in our button cell has one of the
`following layer sequences:
`
`so
`
`65
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 7
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`
`
`US 9,496,581 B2
`
`5
`negative electrode/separator/positive electrode/separator
`or
`positive electrode/separator/negative electrode/separator.
`Assemblies such as these can be produced and wound
`very easily without short circuits occurring between elec-
`trodes of opposite polarity.
`The separators which can be used in our button cell are
`preferably films composed of at least one plastic, in particu-
`lar of at least one polyolefin. By way of example, the at least
`one polyolefin may be polyethylene. However, it is also
`possible to use multilayer separators, for example, separa-
`tors composed of a sequence of different polyolefin layers,
`for example, with the sequence polyethylene/polypropylene/
`polyethylene.
`It is not essential to use a plurality of separate separators
`to produce assemblies with the abovementioned sequence.
`In fact, a separator can also be looped around the end of one
`of the electrodes, thus resulting in both sides of this elec-
`trode being covered by the separator.
`The separators which can preferably be used in our button
`cell preferably have a thickness of between 3 µm and 100
`µm, in particular of between 10 µm and 50 µm.
`The electrodes preferably have a thickness of between 10
`µm and 1000 µm, in particular of between 30 µm and 500
`
`Preferably, the negative electrode and the positive elec-
`trode in the electrode-separator assembly are arranged offset
`with respect to one another within the assembly. In this case,
`an offset arrangement is intended to mean that the electrodes
`are arranged such that this results in a respectively different
`separation between the electrodes and the flat bottom and
`top areas in the button cell. In the simplest case, for example,
`a positive and a negative electrode can be slightly offset as
`strips of the same width applied to the opposite sides of a
`separator ribbon, as a result of which the distance between
`the positive electrode and the upper separator edge is greater
`than the comparable distance measured from the negative
`electrode. This then applies in the opposite sense, of course,
`to the distance from the lower separator edge.
`Particularly preferably, preferably as a result of this offset
`arrangement, the positive electrode, in particular an edge of
`the positive electrode, rests directly on the cup part, in
`particular in the flat bottom area of the cup part, while the
`negative electrode, in particular an edge of the negative
`electrode, rests directly on the top part, in particular in the
`flat top area of the top part. In this example, a direct
`electrical and mechanical contact is made between the
`electrodes and the cup and top parts. The offset arrangement
`of the electrodes with respect to one another therefore makes
`it possible for the electrodes to make contact with the
`respective housing parts, without any need to use additional
`electrical contacts and connecting means.
`However, alternatively, it is also preferable for at least one
`of the electrodes, preferably both the at least one negative
`electrode and the at least one positive electrode in our button
`cell, to be connected to the flat bottom and top areas via one
`or more output conductors. By way of example, the output
`conductors may be output-conductor lugs composed of
`copper or some other suitable metal. On the electrode side,
`the output conductors may, for example, be connected to a
`current collector. The output conductors can be connected to
`the housing and/or to the current collectors by, for example,
`welding or via an clamped joint.
`In the simplest case, the current collectors of the positive
`and negative electrodes can also themselves act as output
`conductors. Collectors such as these are generally metallic
`films or meshes which are embedded in the respective
`
`5
`
`6
`electrode material. Uncovered subareas, in particular end
`pieces, of collectors such as these can be bent around and
`can be brought into contact with the button cell housing.
`The use of output conductors may be particularly advan-
`tageous if the negative electrode and the positive electrode
`within the assembly are arranged with respect to one another
`such that this results in the electrodes each being at the same
`distance from the flat bottom and top areas. Or, in other
`words, if the electrodes are not arranged offset with respect
`10 to one another within the electrode-separator assembly, as
`has been described above.
`However, if the distance between electrodes of opposite
`polarity and the flat bottom and top areas is the same, this
`results in the risk of a positive and a negative electrode
`15 touching the metallic cup or top part at the same time, thus
`resulting in a short circuit. Preferably, the button cell may
`therefore comprise at least one insulating means, which
`prevents a direct mechanical and electrical contact between
`the end faces of the winding and the flat bottom and top
`20 areas.
`In one development, it is preferable for the electrodes in
`our button cell such as this to be connected via the already
`mentioned separate output conductors to the flat bottom and
`top areas. These ensure the electrical contact between the
`25 electrodes and the housing.
`In this case, it is preferable for at least a subsection of the
`output conductor or conductors in the bottom area and in the
`top area of the housing to rest flat on the inside of the
`housing half-parts. Ideally, the output conductors naturally
`30 make electrical contact with the insides of the housing when
`they are at least slightly pressed against the housing (if they
`are not welded to it in any case). This can be achieved
`surprisingly efficiently by a suitable arrangement of the
`winding core that has been mentioned, in our button cell.
`By way of example, the insulating means may be a flat
`layer composed of plastic, for example, a plastic film, which
`is arranged between the end faces of the winding and the flat
`bottom and top areas of the housing of our button cell.
`Corresponding to the above statements, the button cell is,
`40 in particular, a rechargeable button cell. Our button cell
`particularly preferably has at least one lithium-intercalating
`electrode.
`The ratio of the height to the diameter of button cells is,
`by definition, less than 1. For our button cell, this ratio is
`45 particularly preferably between 0.1 and 0.9, in particular
`between 0.15 and 0.7. In this case, the height means the
`distance between the flat bottom area and the flat top area
`parallel to it. The diameter means the maximum distance
`between two points on the casing area of the button cell.
`The button cell is particularly preferably a button cell
`which is not beaded over, as is described in DE Patent
`Application 10 2009 017 514.8, mentioned above. Corre-
`spondingly, there is preferably an exclusively force-fitting
`connection between the housing half-parts. Therefore, our
`55 button cell does not have a beaded-over cup edge, as is
`always the case with known button cells. The button cell is
`closed without being beaded over.
`Button cells such as these which are not beaded over
`generally make use of conventional cell cups and cell tops,
`60 which each have a bottom area and a top area, a casing area,
`an edge area which is arranged between the bottom and top
`areas and the casing area, and a cut edge. Together, the cell
`cup and cell top form a housing, which forms a receptacle
`for the conventional internal components of a button cell
`65 such as electrodes, separator and the like. As in the normal
`way, the bottom area of the cell cup and the top area of the
`cell top are aligned essentially parallel to one another in this
`
`so
`
`35
`
`Eve Energy Co., Ltd v. Varta Microbattery Gmbh
`
`Eve Ex. 1026, p. 8
`
`
`
`US 9,496,581 B2
`
`7
`housing. The casing areas of the cell cup and cell top in the
`finished button cell are aligned essentially at right angles to
`the bottom and top areas, and preferably have an essentially
`cylindrical geometry. The internal and external radii of the
`cell cup and cell top are preferably essentially constant in the
`casing areas. The edge areas, which have been mentioned, of
`the cell cup and cell top form the transition between the
`casing areas and the top and bottom areas. They are pref-
`erably therefore bounded on the one hand by essentially flat
`bottom and top areas, and on the other hand by the essen-
`tially cylindrical casing areas, which are arranged at right
`angles to them. By way of example, the edge areas may be
`in the form of a sharp edge, or else may be rounded.
`The procedure for producing a button cell which is not
`beaded over is generally to first of all apply a seal to the
`casing area of a cell top. In a further step, the cell top is then
`inserted, with the seal fitted, into a cell cup thus resulting in
`an area in which the casing areas of the cell cup and cell top
`overlap. The size of the overlap area and the ratio of the
`overlapping area to the non-overlapping areas are in this
`case governed by the respective height of the casing areas of
`the cell cup and cell top, and by the depth of the insertion.
`With regard to the casing area of the cell top, it is preferable
`for between 20% and 99%, in particular between 30% and
`99%, particularly preferably between 50% and 99%, to
`overlap the casing area of the cell cup (the percentages each
`relate to the height of the casing or of the casing area).
`Before being inserted into the housing cup and/or the
`housing top, the other conventional components of a button
`cell (electrodes, separator, electrolyte and the like) are
`inserted. After the cell top has been inserted completely into
`the cell cup a pressure is exerted on the casing area of the
`cell cup, in particular in the area of the cut edge, to seal the
`housing. In this case, a joined-together housing part should
`as far as possible not be subjected to any loads, or only to
`very small loads, in the axial direction. Therefore, the
`pressure is applied in particular radially. Apart from the
`sealing of the housing which has already been mentioned the
`external diameter of the cell housing can therefore also be
`calibrated.
`It is particularly important for the heights of the casing
`areas of the cell cup and cell top to be matched to one
`another such that the cut edge of the cell cup is pressed
`against the casing area of the cell top by the pressure on the
`casing area of the cell cup. The heights of the casing areas
`are therefore preferably chosen such that it is impossible to
`bend the cut edge of the cell cup around inward over the
`edge area of the cell top which has been completely inserted
`into the cell cup. Correspondingly, the edge of the cell cup
`is not beaded over the edge area of the cell top. In conse-
`quence, the cell cup of a button cell manufactured using our
`method has a casing area with an essentially constant radius
`in the direction of the cut edge.
`In the case of button cells produced using a method such
`as this, there is preferably an exclusively force-fitting con-
`nection between the housing components comprising the
`cell cup, the cell top and the seal. This ensures that the
`components are therefore held together in a preferred man-
`ner, essentially only by static-friction force.
`Button cells without any beading over are particularly
`preferably produced using a cell cup which is conical at least
`in one subarea of its casing, such that at least its internal
`diameter increases in the direction of the cut edge. This
`makes it considerably easier to insert the cell top into the cell
`cup. The dimensions of the cell cup and cell top are
`p