EP1872426A1

EP1872426A1 - Electrochemical element

Info

Publication number: EP1872426A1
Application number: EP06724078A
Authority: EP
Inventors: Konrad Holl; Martin Krebs; Hartmut Weidenbacher; Bernd Kreidler; Hermann LÖFFELMANN; Dejan Ilic; Magnus Berggren; Staffan Nordlinder; Linda Andersson; Lars-Olof Hennerdal; Anurak Sawatdee
Original assignee: VARTA Microbattery GmbH; Acreo AB
Current assignee: VARTA Microbattery GmbH
Priority date: 2005-04-08
Filing date: 2006-04-06
Publication date: 2008-01-02
Also published as: WO2006105966A1; CN101194385B; JP2008535194A; US20100081049A1; CN103000914A; CN101194385A; DE102005017682A1

Abstract

The invention comprises an electrochemical element having at least one positive and at least one negative electrode (5, 6), the positive and the negative electrodes being arranged next to one another on a flat, electrically nonconductive substrate (1) and being connected to one another via an ionically conductive electrolyte (7). In this case, corresponding individual cells can be connected to one another by a plurality, preferably a multitude, of positive and negative electrodes being arranged next to one another in pairs on the substrate.

Description

Description Galvanic element

The invention relates to a galvanic element having at least one positive and at least one negative electrode and a method for producing such a galvanic element.

Galvanic elements and batteries are known in various designs. Including so-called printed batteries, in which functional parts, in particular electrodes and printed conductors, are printed on a corresponding substrate.

In conventional printed batteries, the arresters are in different levels. There are two collector levels, two electrode levels and one separator level. Such a battery is described in US 4,119,770. A cell is formed as a stack of the various components with the current conductors on the top and bottom of the cell, respectively. Several cells are stacked in a battery. The negative pole of the lower cell is automatically connected to the positive pole of the upper cell.

In US 4,195,121 flexible electrodes are described. The electrodes consist of the active material, a conductive material and an organic binder. As binder, ethylene-acrylic acid is proposed.

Another cell is shown in JP 60155866. It consists of one arrester with laminated anode or cathode. In between there is a gelled electrolyte in a non-woven fabric. The thickening agent is hydroxyethylcellulose. US 4,623,598 describes a contact device for flat batteries. The housing film consists of a two-part conductive layer and an outer insulation layer. Two windows in the insulating layer connect one or the other part of the conductive layer. This housing film is mounted around the electrode stack so that one part of the conductive film contacts the anode, the other contacts the cathode.

An aqueous electrolyte open cell is described in US 5,652,043. Between the electrodes is an electrolyte consisting of a hygroscopic material, an ion-conducting substance and a water-soluble polymer, which holds the electrodes together by an adhesive action. The cell does not dry out under normal climatic conditions. Furthermore, any resulting gas can be released to the environment, thereby preventing the cell from swelling.

No. 5,897,522 describes the use of the flat cell shown in US Pat. No. 5,652,043 in various thin devices such as timer, infuser, thermometer, sugar sensor and electronic game. In WO 0062365 a further improvement of the flat battery is described. Here a chip implemented in the battery or on the battery improves the functionality. It compensates for voltage fluctuations via a DC / DC converter.

All mentioned constructions have the classic stack construction, in which the functional layers, generally five, are arranged one above the other.

Accordingly, the object of the invention is to improve the design of existing galvanic elements and batteries. In particular, a thin or flat battery should be available be made, which has the simplest possible structure. The corresponding battery should also be as easy to produce.

This object is achieved by the galvanic element having the features of claim 1 and the method having the features of claim 16. Preferred embodiments of this galvanic element and this method are shown in dependent claims 2 to 15 and in dependent claim 17, respectively. The wording of all claims is hereby incorporated by reference into the content of this specification.

In the galvanic element according to the invention, the at least one positive and at least one negative electrode are arranged side by side on a planar, electrically non-conductive substrate and connected to one another via an ion-conducting electrolyte. Preferably, the flat substrate is a film, wherein the use of a plastic film is more preferred.

As a result of the arrangement of the positive and negative electrodes next to one another, the functional parts of the galvanic element are arranged substantially one above the other in three planes. These are the planar, electrically non-conductive substrate, the electrodes arranged on the substrate and the ion-conducting electrolyte which connects the two electrodes to each other and at least partially covers them. Accordingly, an overall very flat, thin construction of the galvanic element can be realized. In this regard, the plane of the electrodes is considered to be a plane, which of course may be composed of various parts, such as the respective arresters / collectors and active electrode material. This will be explained in more detail below. As a rule, the positive and negative electrodes will be arranged only on one side of the planar substrate, which will also be described below. However, it is also possible according to the invention to arrange positive and negative electrodes on both sides of the planar substrate in order to realize corresponding other constructions of a galvanic element in this way. According to the invention, however, it is crucial that positive and negative electrodes are arranged side by side (and not in different planes one above the other).

In a further development, the galvanic element according to the invention has conductor tracks which serve as arresters / collectors and which are expediently and preferably arranged between the planar substrate and the actual electrodes or the (electrochemically) active electrode material.

These tracks can be realized in various ways. Thus, it is possible and preferred to use electrically conductive films, in particular metal foils, as such conductor tracks. On the other hand, the conductor tracks can preferably be thin metal layers which can be applied to the substrate by means of a customary metallization method. Finally, it should be emphasized as a particularly preferred variant that the conductor tracks are applied as a printable paste on the substrate. These pastes may also be conventional so-called conductive adhesives. In preferred embodiments of the galvanic element according to the invention, the electrodes or the electrode material itself are applied to the substrate as printable paste. With this variant, the already described advantages of the invention can be achieved particularly well. Corresponding pastes can be applied comparatively simply by standard methods to corresponding substrates, specifically even as thin layers, which is preferred according to the invention. In the galvanic element according to the invention, the positive and negative electrodes are arranged in a plane, but spatially separated from each other. The electrical connection of the positive and the negative electrode takes place exclusively via the ion-conducting electrolyte. In this arrangement, on the one hand, it is imperative that the positive and negative electrodes do not touch. On the other hand, it is expedient not to choose the distance of the two electrodes too large in order to ensure the most space-saving construction possible. Accordingly, it is preferred in the invention if the at least one positive and the at least one negative electrode are arranged on the substrate at a distance of 1 .mu.m to 10 mm from each other. Within this range, distances between 100 μm and 1 mm are preferred.

According to the invention, it is also preferred if a gel-type electrolyte is used as the ion-conducting electrolyte. With such electrolytes, surface constructions, in particular thin flat constructions, can be realized particularly easily. In order to give the gel-type electrolyte improved mechanical stability, it is further preferred according to the invention if the electrolyte is fixed or stabilized in a nonwoven.

In a further development of the invention, the electrolyte is preferably present as a layer, in particular as a thin layer. This layer must be arranged so as to ensure the necessary conductivity between the positive electrode and the negative electrode. In this case, the electrolyte will cover the electrodes in these cases usually at least partially, to provide sufficient conductivity. It is further preferred if the electrolyte or the electrolyte layer completely covers the positive and the negative electrode or, in particular, even extends beyond the corresponding electrode surfaces. protrudes. Such arrangements of the electrolyte layer can also be implemented more easily in terms of manufacturing technology.

In a further development, in the case of the galvanic element according to the invention, a further plastic film may be provided which is arranged above the plane of the electrolyte (based on the layer structure of three levels mentioned above) and accordingly at least partially covers the electrolyte and / or the electrodes. Here, too, it is preferable if complete coverage of the electrolyte and the electrodes takes place.

This further plastic film on the one hand has a protective function for the electrolyte / the electrodes in order to protect them from mechanical damage or from the entry of undesired substances or weather influences. On the other hand, the additional plastic film gives the galvanic element overall improved mechanical stability.

In such constructions with further plastic film, it is further preferred if the plastic film together with the substrate forms a type of housing which encloses the electrolyte and the electrodes in a sealing manner. This will be explained in more detail in connection with the figures.

As an alternative to the other plastic film, a corresponding protection or a corresponding stabilization can also be realized in another way, for example by applying a film or a corresponding layer over the plane of the electrolyte, preferably imprinting it. This layer is usually also made of plastic, d. H. is at least polymer-based.

A particularly preferred variant of the electroplating element according to the invention is present if a plurality, in particular a

Variety, of positive and negative electrodes on the sheet-like, electrically non-conductive substrate are arranged. This arrangement It makes sense, in particular, to follow in pairs, ie in each case one positive electrode and one negative electrode each are arranged in pairs next to one another. In this way, several or many individual cells (with a positive and a negative electrode) can be interconnected. This aspect will be explained later in connection with the figures.

In the last-mentioned preferred embodiments, the substrate has, in particular, conductor tracks via which the electrodes arranged on the substrate (that is to say the plurality or multiplicity of the electrodes) are connected in series and / or parallel circuits. With regard to the application of these interconnects, reference may be made to the above description in connection with the arresters / collectors and referred to.

The inventive method for producing a galvanic element, as described above, is characterized in that the electrodes or the functional parts forming the electrodes are applied to an endless belt serving as a substrate. In this way, a plurality of individual cells can be produced, each with a positive and a negative electrode, wherein, if appropriate, corresponding interconnects for interconnecting these individual cells (in series or in parallel) can be integrated into the process. In preferred embodiments of this method, the endless belt is already provided with the arresters / collectors of the electrodes, which considerably simplifies the process as a whole. Furthermore, it is particularly preferred in the method according to the invention if the electrodes are applied, preferably printed, in the form of a paste, in particular a pressure-type paste, to the substrate or the corresponding arresters. The previous versions have again clarified the advantages associated with the invention. In the formation of the galvanic element as a single cell, there is the advantage of a much thinner and overall uncomplicated construction, since the number of levels in which functional components are arranged, can be reduced. All electrical contacts lie in one plane, so that a complex through-contacting over different levels, in particular over widely separated planes, is eliminated. In addition, the invention makes it possible in a simple manner to interconnect several or many individual cells with one another. It is on the one hand already possible to arrange several or many electrodes in pairs on the flat, electrically non-conductive substrate and to provide on this substrate already corresponding tracks for interconnecting the individual cells. On the other hand, it is possible to fasten already completed individual cells on a further carrier foil, which already has the interconnects necessary for the interconnection of individual cells, and to connect them via corresponding contacting means. Adhesive adhesives customary for fastening can be used here, and a conventional conductive adhesive or conductive ink, for example a corresponding silver-containing conductive adhesive, is typically used for contacting. After completion of the total battery from the several or many individual cells, this can be covered for completion with a (further) cover sheet. This can for example be glued or laminated. As a result, such a battery (as in the case of the further plastic film already described) is mechanically stabilized and protected from external influences, for example weather influences. The electrical contacts of the battery are led out on the carrier film and can be tapped mechanically or likewise with a conductive adhesive.

The galvanic elements according to the invention are available both in the form of a single cell and in the form of several or many individual cells. In comparison with galvanic elements of the prior art, cells are particularly thin and, if necessary, also very flexible. Therefore, the galvanic element according to the invention can be used particularly well in those applications in which a small thickness and optionally high flexibility is desired, ie for example in so-called Smart Cards or Smart Tags.

Further features of the invention will become apparent from the drawings and from the following description of preferred embodiments in conjunction with the subclaims. In this case, the individual features may be implemented individually or in combination with each other in an embodiment of the invention. The particular embodiments described are merely intended to illustrate and to better understand the invention and are in no way limiting. Also the drawings described below are part of the present description, which is hereby confirmed by express reference.

In the drawings show:

1 shows the schematic structure of a galvanic element according to the invention as a single cell with adjacent electrodes. FIG. 2 shows the schematic structure of a galvanic element according to the invention with three individual cells

3 shows the schematic structure of a galvanic element according to the invention with four individual cells (connected in series and in parallel) Fig. 4 shows a schematic section of the production process for the construction of individual cells on an endless belt serving as a substrate.

Fig. 1 shows an inventive galvanic element in the form of a so-called single cell. In this case, so-called collectors / arresters 3, 4 are applied to a flat substrate 1 in the form of an electrically non-conductive, thin plastic film 2. These were applied to the substrate 1 in the form of electrically conductive pastes (preferably silver, copper, nickel, aluminum, indium, bismuth or graphite) and then dried. Such pastes may usually contain binders in the form of polymers, which may be thermally or chemically solidified, for example.

As already explained, the application of the collectors / arresters 3, 4 is not limited to the application of electrically conductive pastes. Similarly, the collectors / arresters 3, 4 may be thin electrically conductive foils (metal foils, plastic foils filled with conductive materials). The connection of these films with the substrate 1 is preferably carried out by cold or hot bonding. In addition, the collectors / arresters 3, 4 can also be represented by conventional metallization processes (vacuum deposition, sputtering, electrodeposition).

On the collector 3, as shown in FIG. 1, the cathode 5 (ie, the corresponding electrode material) is applied. This application is preferably carried out with the aid of a printable paste. However, it is also possible to apply a separately prepared cathode foil. The anode 6 (ie the corresponding electrode material) is applied to the collector 4. Both the cathode 5 and the anode 6 are electrically contacted with the collectors / arresters 3, 4. Here, a loosely resting on the corresponding overall construction of the galva- already sufficient. It may also be a fixed connection between the collectors / arresters 3, 4 and the electrodes 5, 6 may be provided.

Above the electrodes (cathode 5 with arrester 3, anode 6 with arrester 4) there is a gel-like electrolyte 7, which is fixed with a net structure or a fleece 8. In this case, the electrolyte 7 with the nonwoven 8 covers the active electrode material of the cathode 5 and the anode 6.

Above the electrolyte 7 with fleece 8 is another plastic film 2, which on the one hand completely covers the electrolyte 7 and on the other hand projects beyond the dimension of the electrolyte 7. In this way, the substrate 1 and the plastic film 2 form a tightly closing housing for the functional components located between the substrate 1 and the plastic film 2, namely the actual electrodes (5, 3, 6, 4).

Fig. 1 clearly shows the improved thin construction of the galvanic element according to the invention. The actual construction includes only three (stacked) planes, namely the plane of the substrate 1, the plane of the electrodes (cathode 5 with arrester 3, anode 6 with arrester 4, arranged side by side) and the plane of the electrolyte above the plane of the electrodes. In Fig. 1, the preferred embodiment is shown with four levels, in which above the level of the electrolyte nor the further plastic film 2 forms its own level and together with the substrate 1, the tight closing housing for the actual two levels with the functional components.

2 shows the schematic structure of a galvanic element (battery) in which three individual cells with electrodes lying side by side in pairs (ie, three individual cells according to FIG. 1) are connected to one another via electrically conductive paths (printed conductors 9). Thereby higher voltages can be realized. Such series circuits can lead to galvanic elements with voltages of 30 V and higher, which can be produced according to the invention particularly inexpensive and easy.

According to FIG. 3, the schematic structure of a galvanic element (battery) is shown in four individual cells (see FIG. 1) with electrodes lying side by side in pairs. These four single cells are connected both in series and in parallel. Through this construction, different total voltages and capacities or load capacities can be achieved.

Fig. 4 shows schematically a section of the production process according to the invention. In this case, the galvanic elements according to the invention can be produced endlessly (as shown) on a substrate 12 (carrier tape) in the form of an endless belt or even in multiple rows (not shown). The conductor tracks 10 and 11 serving as collectors / arresters are already applied to the substrate 12 prior to the actual production process of the single cell. Then, as described in connection with FIG. 1, the actual electrodes or the corresponding electrode material are applied to the printed conductors 10 and 11 at the locations provided for this purpose. Subsequently, the application of the electrolyte, which is stabilized as a gel-like electrolyte with a nonwoven takes place. Due to the reference to FIG. 1, the actual electrodes and the electrolyte in FIG. 4 are not provided with reference numerals. Finally, a further plastic film in the form of a cover film 13 is applied over the electrolyte, which then closes the respective individual cell on the substrate 12 together with this in the form of a housing. At the end, the individual cells can optionally be separated again or else fed to a plurality of further processing steps. In this context, it should be mentioned that according to FIG. 4 and the rest quite generally, both the substrate 12 and the cover sheet 13 can be made of self-adhesive films. This facilitates, on the one hand, the application of the cover film to the single cell which has been completed in each case. On the other hand, it is possible, if appropriate after separation of the individual cells produced, to mount the substrate 12 directly by gluing on, for example, a printed circuit board without additional adhesive.

example

To produce a 1.5 V battery system, the following procedure is used to produce a galvanic element shown in FIG. 1. The aim in the present case is to realize a zinc-carbon system. This system is only mentioned as an example but is characterized by comparatively low costs.

First, appropriate films are provided for the substrate and the further plastic film serving as the cover film. Here plastic films with low gas and water vapor diffusion rate are preferred, d. H. in particular made of PET, PP or PE. If it is intended to heat-seal these films together later, the provided base films can be laminated with a low-melting additional material. Here it can be z. B. to act a hot melt adhesive from a copolymer based on PE.

First, a collector in the form of a conductive adhesive (based on silver, copper or graphite) is then printed onto the substrate to provide the negative electrode (anode). For the positive electrode (cathode) conductive adhesives based on silver, nickel or graphite are to be mentioned as collector / arrester materials, which are also printed. If you want to provide very thin collectors / arresters, so also offers the vacuum coating. In this case, copper is vapor-deposited as a collector / arrester for the anode and nickel for the cathode in a high vacuum.

Subsequently, the electrode material for the anode is printed on the corresponding collector / arrester. For this purpose, a screen printing method is preferably used. The electrode material is a zinc paste consisting of zinc powder, a suitable binder and a suitable solvent. Similarly, a paste is used for printing the cathode material on the other collector / arrester. This cathode material consists of manganese dioxide (MnO ₂ ), carbon black and / or graphite as the conductive material and a suitable binder and a suitable solvent. Again, it is preferable to work by screen printing.

Finally, the electrolyte is applied in a further process step. The electrolyte is preferably a gelatinous paste. This consists, for example, of an aqueous solution of zinc chloride, it being possible for this solution to be completely or partially predried. The application of the electrolyte is also preferably carried out by a printing process. Preferably, the electrolyte covers (as shown in Fig. 1) both electrodes over the entire surface. As also shown in Fig. 1, the electrolyte may be reinforced and stabilized by a non-woven or net-like material.

The individual cell produced in this way is then covered according to the example with the aid of the second (further) plastic film, ie closed in the manner of a housing. This is done, as mentioned, preferably by means of a heat-sealing method. Likewise, as discussed in connection with Fig. 4, preferably self-adhesive films for the substrate and the other plastic film can be used. This also allows a particularly simple application of the single cell or consisting of several individual cells battery to the corresponding body of the power-supplied unit.

Claims

claims

1. Galvanic element having at least one positive and at least one negative electrode (5, 6), which are arranged side by side on a flat, electrically non-conductive substrate (1) and are connected to each other via an ion-conductive electrolyte (7).

2. Galvanic element according to claim 1, characterized in that it is the sheet-like substrate (1) is a film, in particular a plastic film is.

3. Galvanic element according to one of claims 1 or 2, characterized in that it has as conductors (3, 4) serving conductor tracks, which are preferably arranged between the substrate (1) and the electrodes (5, 6).

4. Galvanic element according to claim 3, characterized in that it has as conductive tracks electrically conductive films, in particular metal foils.

5. Galvanic element according to claim 3, characterized in that it comprises, as strip conductors, thin metal layers which can be applied to the substrate by means of a customary metallization method.

6. Galvanic element according to claim 3, characterized in that it comprises printed conductors, which are applied as a printable paste on the substrate.

7. Galvanic element according to one of the preceding claims, characterized in that it comprises electrodes which are applied as a printable paste on the substrate.

8. Galvanic element according to one of the preceding claims, characterized in that the at least one positive and the at least one negative electrode on the substrate at a distance of 1 .mu.m - 10 mm, preferably between 100 .mu.m - 1 mm, are arranged one another.

9. Galvanic element according to one of the preceding claims, characterized in that it comprises a gel-like electrolyte.

10. Galvanic element according to one of the preceding claims, in particular according to claim 9, characterized in that the electrolyte is fixed in a non-woven (8).

11. Galvanic element according to one of the preceding claims, characterized in that the electrolyte is present as a layer which preferably completely covers the electrodes.

12. Galvanic element according to one of the preceding claims, characterized in that it comprises a further plastic film (2) which at least partially, preferably completely covers the electrolyte (7) and / or the electrodes (5, 6).

13. Galvanic element according to claim 12, characterized in that the further plastic film forms a housing with the substrate, which encloses the electrolyte and the electrodes sealingly.

14. Galvanic element according to one of the preceding claims, characterized in that it comprises a plurality, preferably a plurality, of positive and negative electrodes which are arranged in pairs side by side on the substrate.

15. Galvanic element according to one of the preceding claims, characterized in that the substrate has conductor tracks (9), are connected via the arranged on the substrate electrodes in series and / or parallel circuits.

16. A method for producing a galvanic cell according to any one of the preceding claims, characterized in that the electrodes are applied to an endless belt serving as a substrate (12), which is preferably provided with outgoing conductors (10, 11).

17. The method according to claim 16, characterized in that the electrodes are printed.