DE102021214854A1 - Accumulator unit and method for manufacturing an accumulator unit - Google Patents

Abstract

The invention relates to an accumulator unit (2) having a housing (4) with a first housing part (20) and a plurality of electrode units (8), each electrode unit (8) having an anode (10), a cathode (12) and a separator (14), each electrode unit (8) having two collectors (16,18), namely a primary collector (16) and a secondary collector (18), and wherein several of the primary collectors (16) are electrically conductive are connected to the first housing part (20).

Description

The invention relates to an accumulator unit having a housing with a first housing part and a plurality of electrode units. The invention also relates to a method for producing an accumulator unit.

Accumulators are widely used to store electrical energy. They are also used in the motor vehicle sector, among other things, and serve here in particular as so-called drive or traction batteries for driving hybrid or electric vehicles.

Lithium-ion accumulators are currently of particular interest. With regard to the exact structure, a large number of designs are known here. The production is, for example, in "Heimes, Heiner Hans; Kampker, Achim; Lienemann, Christoph; Locke, Marc; Offermanns, Christian; Michaelis, Sarah; Rahimzei, Ehsan (2018): Production process of a lithium-ion battery cell, Frankfurt am Main, PEM of RWTH Aachen University and VDMA self-printing".

In many applications, a number of lithium-ion cells are first produced to produce a lithium-ion accumulator. For this purpose, the electrochemically active components of the lithium-ion cells, which are combined to form so-called stacks or coils, are housed in round, pouch or prismatic cell housings. A number of these lithium-ion cells are then subsequently processed further to form a battery module, with the corresponding battery module typically being housed in a module housing. Several battery modules manufactured in this way are then finally assembled to form a battery, with the battery also usually being housed, namely in a battery housing.

The invention is based on the object of specifying an advantageously designed accumulator unit and an advantageous method for producing an accumulator unit.

This object is achieved by an accumulator unit having the features of patent claim 1 and by a method having the features of patent claim 10 . The advantages and preferred configurations listed with regard to the accumulator unit can also be transferred to the method and vice versa. Advantageous configurations with expedient developments of the invention are specified in the dependent patent claims.

The method according to the invention is designed for the production of accumulator units according to the invention. This means that at least one accumulator unit according to the invention is produced in the course of carrying out the method.

In this case, the accumulator unit according to the invention is preferably designed as a lithium-ion accumulator. More preferably, the accumulator unit forms a battery module or a battery, in particular a battery module or a battery for the motor vehicle sector. Such a battery is preferably designed as a so-called drive or traction battery for driving a hybrid or electric vehicle. A corresponding battery module or module for short is in turn preferably designed as an assembly for a corresponding drive or traction battery.

Regardless of this, each accumulator unit has a number of electrode units. Each electrode unit in turn has an anode, a cathode and a separator. In this case, each electrode unit is typically formed by a so-called stack or a so-called coil, or else it has a corresponding stack or coil.

The structure and production of such a stack, which is also referred to as a cell stack, or such a roll, which is also referred to as a jelly roll, are described, for example, in “Heimes, Heiner Hans; Kampker, Achim; Lienemann, Christoph; Locke, Marc; Offermanns, Christian; Michaelis, Sarah; Rahimzei, Ehsan (2018): Production process of a lithium-ion battery cell, Frankfurt am Main, PEM of RWTH Aachen University and VDMA self-printing".

In addition, each electrode unit has two so-called collectors, namely a primary collector and a secondary collector. Each electrode unit therefore has a number of components of an accumulator cell, in particular the electrochemically active components.

However, these are not each housed in their own housing, but in a common housing for a plurality of electrode units, namely in a housing with a first housing part. This means that in the manufacture of the accumulator unit, there is no classic cell assembly and therefore not every electrode unit for realizing an accumulator cell has its own cell housing. Rather, the use of cell housings is dispensed with entirely. Instead, a plurality of electrode units are introduced or arranged directly in or in a battery module housing or battery housing. This is simply referred to below as the housing and is part of a battery unit according to the invention.

So instead of providing a separate cell housing for each electrode unit, several electrode units are arranged in a common housing. This common housing typically forms a number of chambers, with exactly one electrode unit preferably being inserted into each chamber. The housing is preferably designed in such a way that in the finished state of the accumulator unit the chambers are sealed off from one another, typically in a liquid-tight or gas-tight manner.

Expediently, the chambers are also at least partially filled with an electrolyte or topped up with an electrolyte in the course of carrying out the method. Depending on the variant, the electrolyte is introduced into the chambers before or after the electrode units are inserted.

As already explained above, each electrode unit has a primary collector and a secondary collector. In addition, the accumulator unit has a plurality of electrode units and the aforementioned housing with the first housing part. In this case, two or more of the primary conductors are then electrically conductively connected to the first housing part, and in particular all the primary conductors are electrically conductively connected to the first housing part.

Also preferred is an embodiment variant in which the first housing part has two metal sheets, for example made of aluminum, which are mechanically connected to one another via an insulator element and electrically insulated from one another. In this case, that insulator element is made of glass or ceramic, for example. In this case, the insulator element is further preferably designed in the form of a strip. In order to connect the two metal sheets, for example, each metal sheet is then embedded in the insulator element on one side or glued to the insulator element on one side.

An embodiment is also advantageous in which the first housing part forms two busbars that are electrically insulated from one another, namely a primary busbar and a secondary busbar, with the primary conductors of the electrode units being electrically conductively connected to the primary busbar and with the secondary conductors of the Electrode units are electrically connected to the secondary busbar. This means that in this embodiment of the accumulator unit, the first housing part also assumes the function of cell connectors and that, accordingly, classic cell connectors are dispensed with.

It is also expedient if the primary arresters are mechanically connected to the first housing part. Depending on the design variant, the mechanical connections are designed either as repeatedly detachable connections or as non-detachable connections. Connections by soldering or welding, ie soldered or welded connections, are preferred here.

According to one embodiment variant, the mechanical connections are formed on the inside of the housing of the accumulator unit and accordingly on the inside of the first housing part. Alternatively, the mechanical connections are formed on the outside of the first housing part and thus on the outside of the housing.

If the mechanical connections are positioned on the outside, then the first housing part typically has openings or breakthroughs, ie, for example, holes or slots. The primary conductors are then routed to the outside through these openings or openings in the first housing part and are mechanically connected, in particular welded, to the first housing part on the outside.

A design variant in which the housing has two halves that are electrically insulated from one another is also expedient. Irrespective of this, in the course of the method according to the invention, the first housing part and a second housing part are preferably initially prefabricated and mechanically connected to one another at a later point in time, in particular welded. However, the first housing part and the second housing part typically do not correspond to the two halves of the housing.

The second housing part typically forms a housing base or base of the housing for short. More preferably, the second housing part forms a plurality of partitions, by which the electrode units are separated from one another in the finished accumulator unit. In addition, an embodiment variant is preferred in which the second housing part forms a housing base, several partitions and two side walls of the housing, in particular two of a total of four side walls. Side walls are understood to be walls that close off the housing from the outside in the finished state of the accumulator unit.

Another advantage is an embodiment variant in which two extruded profiles made of metal, for example aluminum, are first produced to form the second housing part. These are then more preferably mechanically connected to one another via a further insulator element den and electrically isolated from each other. An expedient design of the extruded profiles is one in which they each have a profile cross-section that is designed like a comb, which means, for example, has several walls arranged essentially parallel to one another, which are connected to one another via a wall running transversely.

In addition, an embodiment variant of the accumulator unit is advantageous in which the first housing part forms a housing cover, or cover for short. According to a further embodiment variant, the first housing part forms a cover and two side walls of the housing.

A variant of the method is then expediently provided in which a first housing part as described above and a second housing part as described above are initially prefabricated. The prefabricated housing parts are then more preferably permanently connected to one another at a later point in time, for example by being welded or glued to one another.

As already explained, the advantages and developments described in connection with the accumulator unit can also be applied to the method and vice versa.

In the course of the process, a housing is typically produced with an insulating material running roughly in the middle, e.g. a glass solder. For this purpose, for example, two extruded profiles are first produced, which are then joined. Then several electrode units, for example stacks, are used and a cover, which also has an insulating layer in the middle, is applied.

The conductors of the electrode units, which are in the form of small flags, for example, are preferably welded directly to the cover, which then expediently functions as a busbar. In some process variants, the arresters are welded on before the electrode units are inserted into the housing. Irrespective of this, the arresters are preferably welded to the cover simply by welding from below. Alternatively, the conductors can be threaded through suitable slots or holes in the cover that have previously been cut out, punched or lasered. The arresters are then typically folded over and welded in place. When welding, the seal is preferably made directly.

Depending on the design variant, two side parts or side walls of the housing are designed, for example, as part of a housing part, which forms the housing cover or cover for short. In this case, the side walls are in particular folded down when this housing part is put on. Alternatively, these side walls are realized during the manufacture of the rest of the housing. The first variant requires less welding effort. The latter tends to be more suitable for realizing the function of a tie rod with greater material thickness for the housing.

According to a further embodiment variant, the first housing part and the second housing part are electrically insulated from one another in the completed state of the housing. In this case, for example, the second housing part is made from an electrically insulating material or is coated with an electrically insulating material, for example with an electrically insulating paint. In this case, the first housing part is preferably designed according to an embodiment variant described above. The first housing part preferably forms a housing cover, or cover for short, and this cover is more preferably electrically insulated from the rest of the housing in the completed state of the housing. Typically, the second housing part forms the remainder of the housing.

The method according to the invention described above preferably produces accumulator units in which the electrode units of such an accumulator unit form a bipolar electrode arrangement for the targeted increase in the voltage of the finished accumulator unit and in which, in particular, the electrode units of such an accumulator unit are electrically connected to one another via a parallel connection . However, the already explained renunciation of a classic cell assembly and the use of cell housings is also advantageous in the realization of accumulator units in which the electrode units are electrically connected to one another via a series connection.

In this case, the electrode units are then preferably insulated from one another. It is provided that the housing (in particular the bottom, side walls and partitions/cell dividers) is potential-free. The conductors are then welded to electrically conductive plates, for example, in order to implement the interconnection. Conveniently, these plates are isolated from each other and from the rest of the housing. The insulation takes place, for example, by applying a flat plastic insulation to the housing or housing parts, which is or are made of aluminum, for example. The housing cover is made of a plastic, for example. It can be a long-term stable, form-fitting connection between Alumi nium and plastic components can be realized. The conductors of the electrode units are preferably inserted through slits/recesses in the plastic plate/cover and then through slits in the metal plates or next to the metal plates, then folded over and welded.

In both variants, parallel connection and series connection, it can be assumed that the surfaces do not have to be smooth, i.e. that the weld seams, i.e. at least on the arresters, are preferably not reworked, for example by polishing etc..

Furthermore, buffers, for example compression pads, are provided in some embodiment variants for the implementation of classic solutions against so-called pressure-swelling forces. These are then positioned in the housing and arranged between the electrode units. They provide space for the electrode units to expand in volume over their service life.

• 1 in einer Draufsicht ein Teil einer Akkumulatoreinheit mit mehreren Elektroden-Einheiten eingesetzt in ein Gehäuseteil für eine Parallelverschaltung der Elektroden-Einheiten,
• 2 in einer Seitenansicht ein Strang-Press-Profil für das Gehäuseteil,
• 3 in der Draufsicht das Gehäuseteil,
• 4 in einer Seitenansicht ein weiteres Gehäuseteil für die Parallelverschaltung der Elektroden-Einheiten,
• 5 in der Draufsicht eine alternative Ausführung des Gehäuseteils gemäß 3 für eine Serienverschaltung der Elektroden-Einheiten, und
• 6 in einer Draufsicht eine Anordnung von Zellverbindern für die Serienverschaltung der Elektroden-Einheiten.

Further advantages, features and details of the invention result from the claims, the following description of preferred embodiments and with reference to the schematic drawings. Show in it:

• 1 in a top view, part of a battery unit with several electrode units inserted into a housing part for parallel connection of the electrode units,
• 2 in a side view, an extruded profile for the housing part,
• 3 the top view of the housing part,
• 4 a side view of another housing part for the parallel connection of the electrode units,
• 5 in plan view an alternative embodiment of the housing part according to 3 for a series connection of the electrode units, and
• 6 in a top view, an arrangement of cell connectors for the series connection of the electrode units.

Corresponding parts are provided with the same reference symbols in all figures.

A battery unit 2 described below as an example is designed as a battery module, for example for a drive or traction battery for driving a hybrid or electric vehicle. It has a height, a width and a depth and is correspondingly extended in a height direction, a width direction and a depth direction. In this case, the height direction, width direction and depth direction correspond to three orthogonal spatial directions.

In 1 a part of the accumulator unit 2 is shown schematically. The representation shows a view in height direction. The latitude direction points in 1 from left to right and the depth direction from bottom to top. is indicated in 1 a housing 4 of the accumulator unit 2, which forms a plurality of chambers 6. Exactly one electrode unit 8 is placed in each of the chambers 6 in the exemplary embodiment.

Each electrode unit 8 is in 1 represented schematically by a frame and has at least one anode 10, at least one cathode 12 and at least one separator 14. Anode 10, cathode 12 and separator 14 are only indicated by dashed lines.

Depending on the embodiment variant, each electrode unit 8 is preferably formed by a so-called stack or a so-called coil. The structure and production of such a stack, which is also referred to as a cell stack, or such a roll, which is also referred to as a jelly roll, are described, for example, in “Heimes, Heiner Hans; Kampker, Achim; Lienemann, Christoph; Locke, Marc; Offermanns, Christian; Michaelis, Sarah; Rahimzei, Ehsan (2018): Production process of a lithium-ion battery cell, Frankfurt am Main, PEM of RWTH Aachen University and VDMA self-printing".

In addition, each electrode unit 8 has two collectors 16, 18, namely a primary collector 16 and a secondary collector 18. In this way, a cathode connection and an anode connection are realized for each electrode unit 8. The electrode units 8 are in accordance with the embodiment 1 arranged in the housing 4 such that all primary arresters 16 are arranged in a first row and all secondary arresters 18 in a second row.

Furthermore, the electrode units 8 of the accumulator unit 2 do not have their own cell housings or cell housings. Instead, the electrode units 8 are inserted directly into the common housing 4, a module housing. The housing 4 is preferably designed in such a way that its chambers 6 are sealed off from one another in the finished state of the accumulator unit 2, typically in a liquid-tight or gas-tight manner.

The chambers 6 are expediently at least partially filled with an electrolyte or topped up with an electrolyte in the course of the production of the accumulator unit 2 . Depending on the version tion variant, the electrolyte is introduced into the chambers 6 before or after the insertion of the electrode units 8 .

In the finished state, the housing 4 preferably has two halves that are electrically insulated from one another. In the exemplary embodiment, the housing 4 is manufactured by initially prefabricating a first housing part 20 and a second housing part 22 . However, the first housing part 20 and the second housing part 22 do not correspond to the two halves of the housing 4.

The second housing part 22 is in 3 implied. The illustration again shows a view in the height direction. The width direction is again from left to right and the depth direction is from bottom to top. The second housing part 22 forms a housing base or base 24 for short of the housing 4, two side walls 26 and a plurality of partition walls 28.

To form the second housing part 22, two extruded profiles 30 made of metal, for example aluminum, are first produced in the exemplary embodiment. Such an extruded profile 30 is in 2 played back. The illustration shows a view in the depth direction. The width direction is left to right and the height direction is top to bottom. How out 2 it can be seen that the extruded profile 30 in the exemplary embodiment has a profile cross-section that is configured like a comb.

The two extruded profiles 30 are then joined so that they are mechanically connected to one another via an insulator element 32 and electrically insulated from one another. The insulator element 32 is made of glass, for example, and divides the base 24, the two side walls 26 and the dividing walls 28 of the second housing part 22 into two halves that are insulated from one another.

The first housing part 20 is in 4 implied. The illustration shows a view in the width direction. The depth direction is left to right and the height direction is top to bottom. The first housing part 20 forms a housing cover or cover 24 for short of the housing 4 and two further side walls 36. The housing 4 has four side walls 26, 36 overall, namely the two side walls 26 of the second housing part 22 and the two side walls 36 of the first housing part 20. In the exemplary embodiment, the first housing part 20 is made of two metal sheets 38, 39, for example made of aluminum. Analogously to the two extruded profiles 30, the metal sheets 38, 39 are also joined, so that they are subsequently mechanically connected to one another via an insulator element 40 and electrically insulated from one another. The insulator element 40 is in turn made of glass, for example.

In the exemplary embodiment, the two prefabricated housing parts 20, 22 are brought together and welded to one another to complete the housing 4. In this case, the metal sheets 38, 39 are still bent, if this has not already happened before joining. this is in 4 implied. The bent sections then form the side walls 36 . The two previously mentioned halves which are insulated from one another are then formed in the finished housing 4 by the two insulator elements 32,40.

According to an alternative embodiment, the two extruded profiles 30 described above are joined and then two metal sheets are welded on as side walls 36, so that the second housing part 22 then has all four side walls 26,36. The first housing part 20 then only forms the cover 34 . The metal sheets 38, 39 used for this are then dimensioned correspondingly smaller.

As already explained above, each electrode unit 8 has a primary collector 16 and a secondary collector 18 . All conductors 16, 18 are electrically conductively connected to the first housing part 20, in particular welded, in the course of the production of the accumulator unit 2. In the finished state, the primary conductors 16 are then connected to one of the two metal sheets 38 and the secondary conductors 18 are connected to the other of the two metal sheets 39 . The metal sheets 38, 39 therefore form two mutually insulated busbars 38, 39, namely a primary busbar 38 and a secondary busbar 39, via which the electrode units 8 are connected to one another in parallel. With an interconnection implemented in this way, for example, the formation of classic connection terminals is then also dispensed with.

In the embodiment variants described above, the electrode units 8 are connected in parallel. However, the already explained omission of a classic cell assembly and the use of cell housings is also advantageous in the realization of accumulator units 2 in which the electrode units 8 are electrically connected to one another via a series connection.

Insulation of the electrode units 8 from one another is then preferably implemented here. It is provided that the housing 4 is potential-free. The conductors 16,18 then become Bei play with electrically conductive plate 42 welded to realize the interconnection. These small plates 42 then serve as quasi cell connectors and are expediently insulated from one another and from the rest of the housing 4 . The insulation takes place, for example, by applying a flat plastic insulation to the housing 4 or housing parts 20, 22, which is or are made of aluminum, for example. The housing cover is made of a plastic, for example. A long-term stable, form-fitting connection can be realized between aluminum and plastic components.

In 5 an embodiment variant of the second housing part 22 for a series connection is indicated. It forms the floor 24, the partitions 28 and all four side walls 26,36. An isolator element 32, as in 3 , is not provided here. This embodiment is therefore preferably made from only one extruded profile 30 to which two metal sheets are welded to form the side walls 36 . For insulation, this structural unit is then coated with an insulating paint, for example.

6 shows a matching arrangement of small plates 42, via which the electrode units 8, in 6 indicated by dashed frames, are then connected to one another in series. K stands for cathode connection and A for anode connection. Accordingly, the electrode units 8 are arranged in such a way that the collectors, ie primary collectors 16 and secondary collectors 18, alternate in the upper row and correspondingly in the lower row.

According to one variant, a battery unit 2 with series connection is produced as follows: First, an extruded profile 30 is produced to form a base 24, the partition walls 28 and two side walls 26. Additional side parts are then welded on as side walls 36. Then the electrode units 8, which are insulated from the housing 4, are inserted. Then the metal plates 42, which are embedded, for example, in a plastic cover 34, are heated and the cover is put on. The connection is thus closed locally “on its own” or with a little pressure.

In a slightly modified version, two of the outer plates 42, i.e. in 6 on the left and the right side, designed as an extended plate 42. To the outside, these then form the overall poles of the accumulator unit 2 with series connection. They are designed to be larger in order to simplify the connection of the accumulator unit 2, ie the integration into a system.

Reference List

2

accumulator unit

4

Housing

6

chamber

8th

electrode unit

10

anode

12

cathode

14

separator

16

primary drain

18

secondary arrester

20

first housing part

22

second housing part

24

Floor

26

Side wall

28

partition wall

30

extruded profile

32

isolator element

34

Lid

36

Side wall

38

Sheet metal/primary busbar

39

Sheet metal/secondary busbar

40

isolator element

42

Tile

Claims (10)

Accumulator unit (2) having a housing (4) with a first housing part (20) and having a plurality of electrode units (8), wherein - each electrode unit (8) has an anode (10), a cathode (12) and a separator (14), - Each electrode unit (8) has two conductors (16,18), namely a primary conductor (16) and a secondary conductor (18), and - Several of the primary conductors (16) are electrically conductively connected to the first housing part (20). Accumulator unit (2) after claim 1 , wherein the first housing part (20) has two metal sheets (38,39) which are mechanically connected to one another via an insulator element (40) and electrically insulated from one another. Accumulator unit (2) after claim 1 or 2 , wherein the insulator element (40) is formed from a glass or a ceramic. Accumulator unit (2) according to one of Claims 1 until 3 , the first housing part (20) forming two busbars (38, 39) which are electrically insulated from one another, namely a primary busbar (38) and a secondary busbar (39), the primary collectors (16) of the electrode units (8) having the primary busbar (38) are electrically conductively connected and the secondary conductors (18) of the electrode units (8) are electrically conductively connected to the secondary busbar (39). Accumulator unit (2) according to one of Claims 1 until 4 , wherein the primary arresters (16) are mechanically connected to the first housing part (20). Accumulator unit (2) according to one of Claims 1 until 5 , wherein the primary conductors (16) are led to the outside through openings in the first housing part (20) and are mechanically connected to the first housing part (20) on the outside. Accumulator unit (2) according to one of Claims 1 until 6 , wherein the housing (4) has two halves mechanically connected to one another and electrically insulated from one another. Accumulator unit (2) according to one of Claims 1 until 7 , wherein two extruded profiles (30) made of metal are mechanically connected to one another and electrically insulated from one another to form the housing (4). Accumulator unit (2) according to one of Claims 1 until 8th , wherein the first housing part (20) forms a cover (34) and two side walls (36) of the housing (4). A method for producing an accumulator unit (2) according to any one of the preceding claims, wherein - the accumulator unit (2) has a housing (4) with a first housing part (20) and a plurality of electrode units (8), - each electrode unit (8) has an anode (10), a cathode (12) and a separator (14), - Each electrode unit (8) has two conductors (16,18), namely a primary conductor (16) and a secondary conductor (18), and - Several of the primary conductors (16) are electrically conductively connected to the first housing part (20).

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