DE102017216193A1 - Process for the production of electrodes - Google Patents

Abstract

The invention relates to a method for producing electrodes (21, 22) from strip-shaped material (66, 82) with the following method steps: First, a discontinuous longitudinal section (102) is produced in the edge region (100) of the strip-shaped material (66, 82) In this case, connections (104) remain in the corner region (110) of the contact lugs (35, 36) between them and excess material (106) of the band-shaped material (66, 82 The transport of the strip-shaped material (66, 82) treated in accordance with the above method steps now proceeds into a conveying plane, in which the separation of the excess material (106) in the separating direction (108) takes place.

Description

Technical area

The invention relates to a method for producing electrodes from strip-shaped materials, to a battery cell and their use.

State of the art

The electrical energy can be stored by means of batteries. Batteries convert chemical reaction energy into electrical energy. Here, a distinction is made between primary batteries and secondary batteries. Primary batteries are only functional once, while secondary batteries, also referred to as accumulators, are rechargeable. In particular, so-called lithium-ion battery cells are used in an accumulator. These are characterized among other things by high energy densities, thermal stability with a very low self-discharge.

Lithium-ion battery cells have a positive electrode, also referred to as a cathode, and a negative electrode, also referred to as an anode. The cathode and the anode each comprise a current conductor, on which an active material is applied. The electrodes of the battery cell are formed like a foil and stacked, for example, to form an electrode stack with the interposition of a separator which separates the anode from the cathode. The electrodes may also be bonded to an electrode coil or in some other way form an electrode unit.

The two electrodes of the electrode unit are electrically connected to poles of the battery cell, which are also referred to as terminals. The electrodes and separator are surrounded by a generally liquid electrolyte. The battery cell further comprises a cell housing, which is made of aluminum, for example. As a rule, the cell housing is prismatic, in particular cuboid and pressure-resistant. But other forms of housing, such as circular cylindrical or flexible pouch cells are known.

An essential aim in the development of new battery cells is to increase the electrochemical useful volume in the battery cell. The electrode stack has proven to be the most suitable design of an electrode unit for maximizing the useful volume, since it can be produced both prismatically and in any other geometry.

Disclosure of the invention

1. a) Erzeugen eines diskontinuierlichen Längsschnittes im Randbereich des bandförmigen Materials,
2. b) Ausbildung von Kontaktfahnen beim diskontinuierlichen Längsschnitt,
3. c) Verbleib einer Verbindung im Eckbereich der Kontaktfahnen zwischen diesen und überschüssigem Material des bandförmigen Materials,
4. d) Transport gemäß der Verfahrensschritte a) bis c) des behandelten bandförmigen Materials in einer Förderebene und
5. e) Abtrennen des überschüssigen Materials in eine Trennrichtung.

A process for the production of electrodes from strip-shaped materials is proposed, wherein at least the following process steps are run through:

1. a) generating a discontinuous longitudinal section in the edge region of the band-shaped material,
2. b) formation of contact lugs in the discontinuous longitudinal section,
3. c) a connection in the corner region of the contact lugs between them and excess material of the band-shaped material,
4. d) transport according to process steps a) to c) of the treated strip-shaped material in a conveying plane and
5. e) separating the excess material in a separating direction.

As a result of the solution proposed according to the invention, contact lugs produced in the production of electrodes can be protected against damage or kinking in the further processing of the electrodes, which is associated with numerous handling processes and deflections.

In an advantageous embodiment of the proposed method according to the invention, the separation of the excess material in the edge region by tearing takes place in a direction substantially perpendicular to a previously performed longitudinal section in the band-shaped material for the electrodes, i. for anode and cathode, has been generated.

In a further embodiment of the method proposed according to the invention, the connections in the corner regions of the contact lugs are designed to be web-shaped for the surplus material surrounding them. As a result, a permanent connection of the contact lugs with the surrounding material is maintained, so that an approximately closed interrupted by the longitudinal section area forms the deflected and handling processes the previously cut contact lugs greater stability and in particular minimizes the risk of damage to the contact lugs.

Finally, it is provided to produce the discontinuous longitudinal section in the band-shaped material for the electrodes by means of a laser. The use of a laser allows a very fine cut, so that in particular the contour of the contact lugs and the width of the webs can be kept low manufacturing technology.

In a further development of the method proposed according to the invention, a burr resulting in separating the excess material in the separating direction is located outside the anodic active material in the case of the production of an anode or outside of the cathodic active material in the case of the production of a cathode.

Furthermore, a battery cell is proposed, which comprises at least two electrodes, which is produced by the method proposed according to the invention.

An inventively proposed battery cell advantageously finds use in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product. In the present context, consumer electronics products are in particular mobile phones, tablets, PCs or notebooks.

Advantages of the invention

The method proposed according to the invention allows the production of electrodes of strip-shaped material, wherein in particular the contact lugs formed in the manufacture of the anode and cathode are effectively protected against damage during the deflection or handling processes necessarily required during the production process. As a rule, the anodes and cathodes are electrically contacted via the contact lugs located laterally thereon, which are subsequently combined. If one of these contact lugs is damaged or even kinked, the electrode stack can not be used. Damage to the tabs or the anodic or cathodic active material may also result in electrical breakdown, i. Short circuits within the electrode stack lead, so this committee represents.

Advantageously, the web or bridge-like connections between the corner regions of the contact lugs and surrounding this later separated in the separation direction material can be made very thin, which is sufficient to protect the contact lugs against damage during deflections, since the mechanical stability of the very thin band-shaped Material from which the anode or the cathode are made, is limited due to the small thickness of the material. Thus, excess material to be separated later from the edge region of the band-shaped electrode material is advantageously used to protect the contact lugs which are of enormous importance later for connection of the electrode stack. The removal process of the excess material, which is present in the edge region of the band-shaped material of the electrode material, takes place, for example, by tearing off, wherein the tears resulting during tearing are located outside of the anodic or cathodic active material, where no breakdown can result.

As a result of the separation process of the excess material, according to the method proposed according to the invention, the waste that occurs is deliberately and can be removed in one piece, so that many small parts or snippets can be avoided. The occurring waste can be specifically sucked for example. Furthermore, it should be emphasized that the separation of the excess material takes place at a favorable position in the process with respect to resulting particles or baubles, etc., since these occur shortly before the next stacking step, and for example not on the revolving wheel. If severed there, particles could fall down onto other electrode or separate segments, which could later cause short circuits when fabricating stacked electrode stacks.

Further, following the method proposed by the present invention, the position of introducing the discontinuous section can be relatively easily realized at various positions of the process. The necessary space for the removal of the waste at the site of the cut itself is eliminated, which allows greater flexibility in the process or plant design, such as the arrangement and the implementation of a laser cut on any pulley.

list of figures

With reference to the drawings, the invention will be explained in more detail below.

• 1 eine schematische Darstellung einer Batteriezelle,
• 2 die wesentlichen Komponenten einer Anlage zur Herstellung von Elektrodenstapeln,
• 3 ein Ausschnitt eines bandförmigen Elektrodenmaterials mit diskontinuierlichem Schnitt und dadurch gebildeten Kontaktfahnen in überschüssigem später abzutrennenden Bereich und
• 4 Elektrodenstapel, die aus Separator- bzw. Elektrodensegmenten aufgebaut sind.

It shows:

• 1 a schematic representation of a battery cell,
• 2 the essential components of a plant for the production of electrode stacks,
• 3 a section of a band-shaped electrode material with discontinuous section and thus formed contact lugs in excess later separated area and
• 4 Electrode stacks, which are composed of separator or electrode segments.

variants

In the following description of embodiments of the invention, the same or similar elements will be denoted by like reference numerals, with repeated description these elements is omitted in individual cases. The figures illustrate the subject matter of the invention only schematically.

1 shows a schematic representation of a battery cell 2 , The battery cell 2 includes a housing 3 , which is prismatic, in the present cuboid, is formed. The housing 3 In the present case, it is designed to be electrically conductive and, for example, made of aluminum. The housing 3 can also be designed in the form of a flexible pouch film.

The battery cell 2 includes a negative terminal 11 and a positive terminal 12 , About the terminals 11 . 12 can one from the battery cell 2 provided voltage can be tapped. Furthermore, the battery cell 2 over the terminals 11 . 12 also be loaded.

Inside the case 3 the battery cell 2 an electrode unit is arranged, which in the present case as an electrode stack 10 is executed. The electrode stack 10 has two electrodes, namely an anode 21 and a cathode 22 , on. The anode 21 and the cathode 22 are each carried out like a film and by a first belt-shaped separator 18 separated from each other. The first belt-shaped separator 18 is ionic conductive, so permeable to lithium ions.

The anode 21 includes an anodic active material 41 and an anodic current collector 31 , The anodic current conductor 31 is made electrically conductive and made of a metal, such as copper. The anodic current conductor 31 is electric with the negative terminal 11 the battery cell 2 connected.

The cathode 22 comprises a cathodic active material 42 and a cathodic current collector 32 , The cathodic current conductor 32 is made electrically conductive and made of a metal, such as aluminum. The cathodic current conductor 32 is electric with the positive terminal 12 the battery cell 2 connected.

2 shows a schematic representation of the components of a plant 58 for the production of electrode stacks 10 ,

2 shows a plant 58 for the production of electrode stacks 10 , At a feeder 60 for a first belt-shaped separator 18 its supply takes place on a transport device 62 , At the transport device 62 It can be a circulating belt or a linear conveyor system 76 or the like. On the transport device 62 becomes the first belt-shaped separator 18 in the transport direction 64 transported.

Above the transport device 62 there is a bobbin supply of a first band-shaped material 66 for a first electrode, eg the cathode. The supply of the first band-shaped material 66 for the first electrode via a plurality of pulleys, not shown here, to a driven wheel 92 , A peripheral surface 94 the driven wheel 92 is a laser 96 or assigned a knife-like cutter. Below the laser 96 or the cutting device is a cut 68 of the first band-shaped material 66 for the first electrode, creating a section 70 ie cathode segments 56 , be generated. The severed section 70 becomes on the peripheral surface 94 the driven wheel 92 within a vacuum range 86 fixed before the respective section 70 on the first belt-shaped separator 18 on the transport device 62 is hung up.

The driven wheel 92 is with a drive 90 provided with an encoder and a drive control, such that the driven wheel 92 alternately accelerates and decelerates alternately during its rotation, so that when filing the sections 70 on the first belt-shaped separator 18 on top of the transport device 62 defined gaps are generated.

Thereafter, the supply takes place 72 a second belt-shaped separator 19 , This is on the transport device 62 transferred, so that the first belt-shaped separator 18 and the regularly spaced separated sections 70 ie the cathode segments 56 , from the second belt-shaped separator 19 are covered.

Subsequently, within a transfer area 74 the transfer of the first belt-shaped separator 18 of the sections spaced therefrom 70 and the second belt-shaped separator 19 to a linear conveyor system 76 , The linear conveyor system 76 For example, includes individual acted upon with negative pressure slide, wherein 2 shows that the linear support system 76 on the underside of individual discrete stacking devices 78 assigned.

After passage of the transfer area 74 Preferably, a laser cut is performed 80 , to the linear conveyor system 76 handed arrangement of the first belt-shaped separator 18 , Section 70 the first electrode, ie the cathode segments 56 , as well as the second belt-shaped separator 19 , These still three-ply stack are laterally via gripping devices or vacuum on each separate vacuum-loadable carriage of the linear conveyor system 76 fixed.

Out 2 shows that the linear conveyor system 76 another powered wheel 92 assigned. This is done with a second band-shaped material 82 for a second electrode applied, which at position 84 preferably by a laser 96 is cut. The second band-shaped material 82 for the second electrode, the anode, separated sections 70 the second electrode will be within the vacuum range 86 on the driven wheel 92 fixed and to those of the individual tables of the linear conveyor system 76 transported arrangements of first belt-shaped separator 18 , the section 70 for the second electrode and the second belt-shaped separator 19 applied.

The obtained, for example, grippers of the linear conveyor system 76 fixed four-ply stack segments 52 , from separator segment 53 of the first belt-shaped separator 18 , the cathode segment 56 , the separator segment 53 of the second belt-shaped separator 19 and the anode segment 55 , see. 4 , become in the outlet area of the linear conveyor system 76 turned by 180 ° and on individual stacking devices 78 stored.

For completeness, it should be mentioned that the driven wheel 92 , which is above the linear conveyor system 76 is arranged, also a vacuum area 86 and a blow-off area 88 having. There is a laser cut 80 of the second band-shaped material 82 for the second electrode preferably by means of a short-pulsed (ns or ps) solid-state laser. Alternative to the laser 96 , which is preferably a solid-state laser, a knife-like cutting device can be used to the individual sections 70 at this point of the second band-shaped material 82 for the second electrode (anode).

3 shows a section of a first band-shaped material 66 from which electrodes are made.

The representation according to 3 is a section of a border area in plan view 100 a first band-shaped material 66 for a first electrode (eg the cathode) or a second band-shaped material 82 for the production of a second electrode (eg the anode). In feed direction 101 of the edge area 100 Seen, a longitudinal section extends 102 at the edge 100 the first and second band-shaped materials 66 . 82 , The longitudinal section 102 in particular by a laser 96 generated.

The laser 96 is doing to generate the longitudinal section 102 guided so that the longitudinal section 102 is designed as a discontinuous longitudinal section. This means that especially in the areas where contact flags 35 for a first electrode, eg the cathode, or contact lugs 36 for a second electrode, such as the anode, are executed, web-like or bridge-like connections 104 remain. The connections 104 , which may be designed in particular web-like or bridge-like, are very narrow and stabilize the respective contact lugs 35 . 36 by adding these with the surplus material surrounding them, later to be separated 106 connect. This will damage the individual tabs 35 . 36 over the one anode 21 (see. 1 ) or a cathode 22 (see. 1 ) at deflections and bends and later formation of the electrode stack 10 from stack segments 52 electrically contacted, avoided. Because of the web-like connections 104 the contact flags 35 . 36 with the surplus material surrounding it, later to be separated 106 stay connected, lie the tabs 35 . 36 even in later deflection or handling processes always in the transport plane of the strip-shaped material 66 . 82 for the first or the second electrode.

Once the band-shaped materials, be it the first band-shaped material 66 for a first electrode (cathode), be it the second band-shaped material 82 for the second electrode (anode), lie in a conveying plane in which no deflections or bends occur more - apart from the stack-like joining of the electrode stack 10 - There is a separation of the excess material 106 , The separation takes place in the separation direction 108 , which are substantially perpendicular to the feed direction 101 extends.

With the proposed method according to the invention, the excess material 106 be used to the later used for electrical contacting tabs 35 . 36 mechanically protect and stabilize, protect against buckling and other damage. This represents a significant safety criterion in the production of electrode stacks 10 because, because of the avoidance of damage to the tabs 35 . 36 the production of rejects is excluded.

4 shows an electrode stack 10 , The electrode stack 10 formed from individual stack segments 52 as shown in 5 , comprises four layers, one separator segment 53 , a cathode segment 56 , another overlying separator segment 53 as well as an anode segment 55 , The cathode segments 56 form the cathode 22 while the anode segments 55 the anode 21 of the electrode stack 10 form.

The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

Claims (7)

Method for producing electrodes (21, 22) from strip-shaped materials (66, 82) with the following method steps: a) generating a discontinuous longitudinal section (102) in the edge region (100) of the strip-shaped material (66, 82), b) formation of contact lugs (35, 36) in the discontinuous longitudinal section (102), c) a connection (104) remains in the corner region (110) of the contact lugs (35, 36) between them and excess material (106) of the band-shaped material (66, 82), d) transport of the according to the process steps a) to c) treated strip material (66, 82) in a conveying plane and e) separating the excess material (106) in the separating direction (108). Method according to Claim 1 , characterized in that the separation of the excess material (106) in the edge region (100) of the band-shaped materials (66, 82) takes place by tearing off. Method according to Claim 1 , characterized in that the connections (104) in the corner regions (110) of the contact lugs (35, 36) to the excess material (106) are web-like or bridge-shaped. Method according to Claim 1 , characterized in that the discontinuous longitudinal section (102) is generated by means of a laser (96). Method according to Claim 1 , characterized in that the separating direction (108) is perpendicular to the feed direction (101) of a first band-shaped material (66) for a first electrode and a second band-shaped material (82) for a second electrode. Battery cell (2) comprising at least two electrodes (21, 22), produced by a method according to one of the preceding claims. Use of a battery cell (2) according to Claim 6 in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product.

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