DE102014100574A1 - Battery cell connecting - Google Patents

Abstract

The invention relates to a method for producing a cell assembly constructed from flat energy storage cells, comprising providing flat energy storage cells, each having two pole terminals; Placing energy storage cells in succession on a transport unit so that the energy storage cells lie in a transport plane; Transport of the energy storage cells through a processing area; Connecting the electrical pole connections of adjacent energy storage cells in the processing area to produce electrical connections; and providing a laminar composite of electrically connected energy storage cells.

Description

The present invention relates to a method for producing a cell composite composed of energy storage cells.

In the field of battery technology so-called lithium-ion batteries are increasingly used, for example, reinforced in the automotive industry. In lithium-ion batteries, different electrolytes can be used, with automobiles increasingly using polymers as electrolytes. In addition, there are different designs in the field of lithium-ion cells, in particular, the three types cylindrical, prismatic and bag-like (coffee-bag cell) are mentioned here.

In a coffee bag cell (also called bag cell or pouch cell) is increasingly used a polymer-based electrolyte, so that the rigid housing of a cell can be omitted. A lightweight and flexible cell construction at low cost is thus feasible. However, such cells are form unstable, which can lead to problems in the further processing of the cells into a cell composite.

Such coffee bag or pouch cells are combined in a subsequent processing step to form a composite of a plurality of pouch cells, wherein such a cell composite forms the lithium-ion battery or alternatively a part of such a lithium-ion battery. Battery represents.

Usually, the individual pouch cells are first stacked to form a dimensionally stable package or composite, wherein the arresters of the individual cells are then electrically connected together in a next step. The individual cells of a composite are connected either electrically in series or in parallel at the end.

Among other things, the electrical contacts of the arresters are problematic in this processing step, since faulty contact points, for example, due to the high currents, have a very high hazard potential. In the worst case, the battery can burn off due to a faulty contact point.

Against this background, an object of the present invention is to provide a method that overcomes the above problems and in particular allows a better contact.

This object is achieved in the aforementioned method for producing a built-up of flat energy storage cell cells cell assembly with the following steps:
Providing flat-structure energy storage cells, each having two pole terminals;
Placing energy storage cells in succession on a transport unit so that the energy storage cells lie in a transport plane;
Transport of the energy storage cells through a processing area;
Connecting the electrical pole connections of adjacent energy storage cells in the processing area to produce electrical connections; and
Provide a laminar composite of electrically connected energy storage cells.

The essential aspect of the method according to the invention is that the electrical connection of the individual cells takes place before stacking. The energy storage cells are transported, for example, in the inline process through a processing area, wherein successively adjacent energy storage cells are electrically connected to each other.

The advantage of this method is to be seen in particular in that the poles or arresters of the energy storage cells are very easy to reach and can be reliably connected or contacted by an easily realizable support.

In addition, other processing steps on the individual cells are well feasible, since the cells are all in one plane, transport level, and thus are easily accessible from above and below.

In a preferred development, the connection of the electrical pole connections by applying connecting elements takes place on the respective pole terminals and arresters and by fixing the connecting elements to the pole terminals, such that an electrical connection is formed. Preferably, the setting of the connecting elements by heat input, for example by laser light. Also, electromagnetic pulse welding is a preferred way to make the connection. Alternatively, it is also possible to fix the connecting elements to the pole terminals with a conductive adhesive.

Preferably, the connecting elements, which are preferably provided as electrically conductive strips of metal, removed from a roll and cut to length.

The laying of the energy storage cells on the transport unit is preferably carried out via a handling device, such as a robot. Preferably, the energy storage cells on the transport unit at least in one direction, preferably a plurality of directions, fixed to one ensure exact position during transport.

In a preferred embodiment, the processing area comprises further processes, such as a curing process, an in-line testing process of electrical parameters, an identification process, a process for applying cooling pads or spacers and / or a process for folding or stacking the laminar composite Energy storage cells to a cell network.

The transport unit preferably comprises a conveyor belt onto which the energy storage cells are placed. The fixation of the energy storage cells can bswp. done by vacuum. Of course, other possibilities of fixation in at least one direction are possible.

As an alternative to a conveyor belt, the transport unit can also have workpiece carriers which transport the energy storage cells.

The transport of the energy storage cells through the processing area is preferably clocked. However, it is also conceivable to transport the energy storage cells continuously.

The energy storage cells are preferably form-unstable energy storage cells. Especially in such cells, the method has great advantages, since it does not require stabilization measures such as frames, etc., in order to connect the cells electrically. The fact that the cells rest on the transport unit in particular flat, the dimensional instability plays a minor role.

Very particularly advantageous, the aforementioned method can be used in so-called pouch cells.

The energy storage cells can also be capacitors, for example supercapacitors.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. Showing:

1 a perspective view of a processing plant for carrying out the method according to the invention;

2a -D schematic representations of various types of pouch cells;

3 a detail view of the system according to 1 ;

4 a schematic representation of three pouch cells with electrical connector, and

5 a schematic representation of a processing plant similar to 1 but with another transport system.

In 1 a processing system is shown and with the reference numeral 10 characterized. For reasons of simplicity, only the components required for the explanation of the invention are shown. The processing plant 10 serves in this embodiment, to process so-called pouch cells, in which case in particular the electrical connection of several pouch cells is meant. It should be noted, however, that in addition to pouch cells, other energy storage cells can be processed. In particular, low-profile, preferably form-unstable or frameless energy storage cells can be processed. Energy storage cells in the form of capacitors, for example. Supercapacitors (supercaps) can be processed.

As already briefly explained, pouch cells (also called coffee-bag cells) are a lithium-ion battery cell with a polymer as the electrolyte, the active part of which is sandwiched in a jacket film and tightly welded, wherein the wrapping film forms a circumferential sealing seam and wherein the cell poles are formed by arresters, which preferably pass through the sealing seam on one side of the cell. Such single, preferably parallelepiped, flat and frameless battery cells are stacked into a cell composite with the individual cells of the cell composite connected in series or in parallel. Such a cell composite of a plurality of individual Pouch cells can form a battery. Alternatively, it is also possible to electrically connect a plurality of such cell assemblies in series or in parallel to provide a battery.

In the 1 shown processing plant is now used to process individual flat-building Pouch cells to a cell composite, which is connected in a - not shown - subsequent processing either with other cell composites or is directly processed into a battery. Low-profile means in in this context, that the upper or lower surface (top or bottom) of the cell is significantly larger than the lateral area (narrow side) of the cell, or in other words, length and width of the cell are significantly greater than the height (thickness).

As mentioned previously, the cell poles are formed by arresters that pass through the cladding foil. This also means that two arresters, namely one for the positive pole and one for the negative pole, are provided per pouch cell, which can be provided on the same side of the cell or alternatively on different sides of the cell. Thus, there are pouch cells in which the two arresters are spaced from one another on a narrow side of the enveloping foil. However, there are also pouch cells in which the two arresters lie on opposite narrow sides, for example the left and the right narrow side, the pouch cell. The terms "left" and "right" are relative to a transport or processing direction of the cell in the processing plant (see. 2 ).

The arrangement of the arresters has an effect in the production of a cell composite in that the electrical connections between the individual cells have to be carried out differently. In the 1 However, shown processing plant is not limited to a specific Pouch cell type, but rather can process different Pouch cell types with differently arranged arresters.

In 2a , b, c and d show several examples of different pouch cells in a series or parallel connected cell composite.

The bottom row, 2a , for example, shows three pouch cells 20 , whose two arresters 22 . 24 on the same side, here the left narrow side, are provided. The three pouch cells shown in this example 20 lie in a row and thus in a plane, the pouch cells are arranged so that the arrester 22 . 24 to the same, here left side show. Beyond that are the pouch cells 20 so that the positive pole and the negative pole alternately from one cell to the next once at the front and once behind (front and rear is related to the transport direction of the cells, cf. 2 ). In other words, this means that the positive pole of a pouch cell is immediately adjacent to the negative pole of the subsequent pouch cell. To this arrangement of pouch cells 20 electrically connect to a series connection, it is necessary, positive and negative poles of adjacent cells each by an electrical connector 26 connect to. In the electrical connector 26 For example, it may be an electrically conductive strip of metal attached to the arresters 22 . 24 is determined. This setting can be done via different joining techniques, for example by welding, soldering, gluing, etc.

This series of electrically connected pouch cells 20 is in 2a as a stack 30 shown in which the series of pouch cells 20 are zigzag superimposed. This pile 30 forms a cell composite 32 in series.

In the above illustration in 2 B is again a series of pouch cells 20 shown, these pouch cells are the arrester 22 . 24 each on opposite sides. In the example shown, the positive poles of the pouch cells are located 20 on the left side, while the minus poles are on the right side. This arrangement of pouch cells 20 allows easy realization of a parallel connection of the cells by the upper arrester 22 via a connector 26 electrically connected to each other and the lower arresters 24 also with a connector 26 be electrically connected.

The adjacent cell composite 30 has the electrically connected Pouch cells 20 on, which in turn are zigzag superimposed.

The same arrangement of pouch cells 20 is in the overlying illustration in 2c shown, in contrast to the previous illustration, the connector 26 is designed as a single connector, that is not as an endless connector that connects all cells together.

Finally, in the upper illustration in 2d a series of pouch cells 20 shown, in which the arrester - are provided on opposite sides of a cell - as before.

As is clear from the 2 results are the pouch cells 20 placed here so that plus and minus poles of two adjacent Pouch cells are on the facing sides (front and back). Thus, plus and minus poles of two adjacent Pouch cells can be 20 easily over a connector 26 connect electrically.

The cell composite 32 the serially connected pouch cells 20 is again achieved by zigzag superimposing the cells.

At this point it should be noted that the exemplified four cell composites 32 not conclusively show all possibilities. Rather, it is of course also possible in a Folding row stacked pouch cells in other ways, for example, by always folding after two or more cells, so that the cell composite then consists of two or more stacks.

In the 1 shown processing plant 10 is designed to produce the aforementioned cell composites from individual pouch cells.

The processing system has a transport system for this purpose 40 on, the workpiece carrier 42 transported from a starting point A to an end point B. Although the transport system 40 in the in 1 . 4 shown processing plant is shown as a single system, the transport system can also consist of several concatenated transport systems.

In the transport system 40 it may be a commercially available transport system for assembly systems, with a transport system being particularly preferred 40 is used, the workpiece carrier 42 can drive individually via linear motors.

The transport system shown here 40 has two parallel guideways 44 each formed as a closed path, so that forms a transport plane and an underlying return transport plane. The workpiece carriers 42 are in the guideways 44 guided on the two transverse sides and are driven by linear motors integrated in the guideways.

The individual workpiece carriers 42 preferably each take a single pouch cell 20 and lead them from point A through the processing plant 10 to endpoint B, where the pouch cells are removed. During transport from A to B, various processing steps are carried out on the pouch cells, which will be discussed below.

The in several magazines 28 provided pouch cells 20 be about a handling system 50 from the magazines 28 taken and on a workpiece carrier 42 hung up. To grasp a pouch cell has the handling system 50 for example, a vacuum suction head 52 , Of course, other embodiments of a gripping arm are also conceivable. After hanging up a pouch cell 20 on the workpiece carrier 42 the workpiece carrier is further transported by one position, that is, approximately a pouch cell length, so that a new pouch cell can again be placed on the subsequent free workpiece carrier.

This forms a train of successive workpiece carriers with overlying pouch cells, thus obtaining an array of pouch cells, as shown in detail in the several examples in US Pat 2 is shown.

The lying on the workpiece carriers and preferably fixed there in one or more directions Pouch cells 20 be in a first editing area 60 with electrical connectors 26 provided, which are preferably unwound from rolls. These connectors 26 are placed on the arresters of adjacent pouch cells, as in the examples in 2 is shown. Because the pouch cells to be loaded 20 lie in one plane, this processing step can be carried out very easily via appropriate handling systems.

In a subsequent workspace 62 become the connectors 26 electrically connected to the corresponding arresters, wherein as a connection process different options are available. For example, it is conceivable to weld the connector to the arrester. This example is in the workspace 62 a welding unit 64 provided that a welding head 65 which drives from above against the connector and the arrester. As counterholds are corresponding elements 66 provided below the pouch cell or the transport plane. The fact that the Pouch cells lie in the same plane, that is not stacked on top of each other, the arresters are easily accessible both from above and from below. This in turn makes it possible to apply the necessary welding forces without running the risk of damaging the arresters.

The workpiece carriers will be step by step through this work area 62 transported so that in turn the Pouch cells can be electrically connected to each other.

At the second work area 62 Executed process step may subsequently follow in the transport direction to the end B of the processing system further process steps. Due to the location of the pouch cells, which lie in one plane on workpiece carriers, process steps can be carried out on each individual pouch cell, regardless of whether, for example, the top side or the bottom side of the pouch cell is to be processed. Such additional process steps may be, for example: curing of applied materials, such as a conductive adhesive for connection between connectors 26 and arresters 22 . 24 , by UV light, air, heat, etc .; an in-line examination of the pouch cells, for example checking of the contacting, testing of contact resistance, testing of other cell parameters; an identification of pouch cells, for example by laser, label, inkjet or labeling; Application of cooling pads, spacers or similar elements; Layup, ie recording and / or handling of the interconnected Pouch cells, which form a laminar composite of cells.

It should be noted at this point that this is an exemplary list and does not conclusively state the possibilities. Other process steps to be performed on pouch cells can easily be integrated into the processing plant.

In 1 is an example of an inline exam unit 70 which checks, for example, the contact quality between connector and arrester.

At the end of the processing plant 10 a flat composite of pouch cells is provided, which can be further processed in different ways. In the embodiment shown, for example, a folding and stacking unit 80 provided the connected pouch cells 20 from the workpiece carriers 42 decreases and on a table 82 stores. This table 82 is displaceable in height, being gradually moved downwards for easier stacking of the pouch cells.

At the end all connected Pouch cells are stacked on the table 82 , Another handling system, not shown, allows this pouch cell stack or cell composite to be removed from the processing system and fed to further processing.

The workpiece carriers, which become free again at the end of the processing plant, run back to the beginning of the processing plant in a return transport plane 10 ,

In 3 is a section of the processing plant 10 again shown in detail. In this detail view are in particular the counter-holder 66 Good to recognize with a welding head 65 the welding unit 64 interact. The welding head 65 itself can be moved in all three directions.

Furthermore, it can be seen from the detailed representation that a workpiece carrier 42 from two workpiece carrier elements 46 is trained. For the two workpiece carrier elements 46 These are cross member elements, which are the area between the two guideways 44 span and laterally on the guideways 44 supported and guided. In addition, a longitudinally extending longitudinal element is provided on this cross member, which extends to the associated second workpiece carrier element.

In the 3 it can be seen that the rear workpiece carrier element 46 has a longitudinal element which extends forward (in the transport direction), while the other workpiece carrier element 46 a longitudinal element which extends backwards against the transport direction and is additionally offset (transverse to the longitudinal direction) to the other longitudinal element.

The respective longitudinal elements can engage in the embodiment shown in corresponding recesses or grooves of the respective opposite associated workpiece carrier element, so that then the longitudinal elements are also supported at the free end.

In this way, two workpiece carrier elements can each workpiece carrier 42 form, which is variable in its longitudinal extent.

This variability is additionally supported by the fact that the individual workpiece carrier elements 46 be driven independently of the others, so that it is easy to adjust the distance between two workpiece carrier elements about it.

During the transport of the pouch cells through the processing plant 10 However, it must be ensured that the distance between the workpiece carrier elements remains the same.

The drive of the workpiece carrier elements can - as previously mentioned - done via linear motors. However, other drive techniques can be used. In addition, of course, classic workpiece carriers that form a single unit can be used. Finally, it should be noted that the transport or transfer system can be chosen arbitrarily and the in 1 shown and described system represents one of many possibilities.

In 4 are in more detail several already connected pouch cells 20 shown. The respective connectors are easy to recognize 26 that connect two different poles of adjacent pouch cells. This arrangement corresponds to that with reference to FIGS 2 explained series connection of several Pouch cells.

The "inline processing" of the pouch cells in the processing plant 10 For example, it also makes it possible to provide each individual pouch cell with a battery management system. This battery management system will - as in 4 shown - placed between the two arresters of a pouch cell and with the two arresters 22 . 24 electrically connected. The battery management system 90 can for example check the cell voltage.

In 5 is a processing plant 10 ' shown, which is essentially the processing facility 10 of the 1 equivalent. On the marked with the same reference numerals elements will therefore not be discussed further. The difference to 1 is the transport system used 40 , While in 1 Workpiece carrier 42 transport the pouch cells is in the processing plant 10 ' from 5 a conveyor belt 43 intended. On this conveyor belt 43 The pouch cells are successively using the handling system 52 placed so that they are transported lying in a row and in a transport plane through the processing area.

If a fixation of the pouch cells on the conveyor belt acting in one or more directions is required, mechanical fixing elements can be provided on the conveyor belt. Alternatively or additionally, a vacuum system may be provided that the pouch cells via suction openings to the conveyor belt 43 sucks and holds on.

As already mentioned, the processing plant is 10 respectively. 10 ' and describe the method of processing pouch cells executed thereon. Of course, other particularly flat-structure energy storage cells can be processed with this method. Especially for form unstable cells, such as pouch cells, the method is particularly advantageous.

Overall, it turns out that the processing plant 10 and in particular the method carried out permits electrical connection / contacting of the connectors with the arresters in high quality. Problems due to contacting errors can thus be significantly reduced. In addition, the inline machining process leaves on the machining equipment 10 additional processing or process steps that can be made to the individual Pouch cells. Each pouch cell is readily accessible from top or bottom to final stacking.

Claims (19)

A method of manufacturing a cellular composite composed of flat-type energy storage cells, comprising Providing flat-structure energy storage cells, each having two pole terminals; Placing energy storage cells in succession on a transport unit so that the energy storage cells lie in a transport plane; Transport of the energy storage cells through a processing area; Connecting the electrical pole connections of adjacent energy storage cells in the processing area to produce electrical connections; and Providing a laminar composite of electrically connected energy storage cells. The method of claim 1, wherein connecting the electrical pole terminals comprises: Providing electrically conductive connecting elements, applying the connecting elements to the respective pole terminals, and Determining the connecting elements to the pole terminals, such that an electrical connection is formed. The method of claim 2, wherein the fixing of the connecting elements by heat input, in particular by laser light or by electromagnetic pulse technology, takes place. The method of claim 2, wherein the fixing of the connecting elements is done by gluing. A method according to claim 2, 3 or 4, wherein the provision of electrically conductive connection elements is effected by feeding from a roll. Method according to one of the preceding claims, wherein the laying of the energy storage cells by a handling device, in particular a robot takes place. Method according to one of claims 1 to 6, wherein the transport unit is a conveyor belt on which the energy storage cells are placed. Method according to one of claims 1 to 6, wherein the transport unit has workpiece carriers to which the energy storage cells are placed. Method according to one of the preceding claims, wherein within the processing area during the transport of the energy storage cells, a curing process is performed. Method according to one of the preceding claims, wherein within the processing area an in-line verification process is performed on the electrically connected energy storage cells, in particular for checking the electrical contact, the contact resistance or other cell parameters. Method according to one of the preceding claims, wherein within the processing area an identification process is performed on the energy storage cells. Method according to one of the preceding claims, wherein cooling pads and / or spacers are applied to the energy storage cells within the processing area. The method of any one of the preceding claims, wherein the laminar array of energy storage cells is folded and / or stacked to provide the cell composite. The method of claim 8, wherein the workpiece carriers each carry an energy storage cell. Method according to one of the preceding claims, wherein the energy storage cells are connected in series. Method according to one of the preceding claims, wherein the transport of the energy storage cells is clocked by the processing area. Method according to one of claims 1 to 15, wherein the transport of the energy storage cells through the processing area is carried out continuously. Method according to one of the preceding claims, wherein the energy storage cells are form unstable frameless energy storage cells. Method according to one of the preceding claims, wherein the energy storage cells are Pouch cells.

Images