DE102019132528A1 - Battery cell group - Google Patents

Abstract

The invention relates to a battery cell group (22), comprising a plurality of individual cells (10), a single cover assembly (30) and a housing (24), with a plurality of partition walls (32) being arranged within the housing (24), which separate the individual cells (10) separate from one another within the housing (24), and wherein all individual cells (10) are electrically connected to the cover assembly (30). The housing (24) has a jacket (26) extending in the longitudinal direction (L) and a first side (28) arranged perpendicular to the jacket (26), the length of the jacket (26) being greater than that in the longitudinal direction (L) the width (S) of the first side (28) transversely to the longitudinal direction (L). Furthermore, the cover assembly (30) is arranged on the first side (28) of the housing (24).

Description

The invention relates to a battery cell group, in particular a battery cell group for a high-voltage storage device in a motor vehicle.

In electric vehicles and hybrid vehicles, suitably dimensioned battery systems are used as high-voltage storage devices for the sole or auxiliary electric drive of the motor vehicle. The high-voltage storage system contains several modules, also known as battery modules, in which several battery cells are combined. The individual battery cells can be connected in series and / or in parallel. Typically, lithium-ion accumulators or batteries are used as battery cells.

The battery system is one of the biggest cost items in electric vehicles. For this reason, it is of crucial importance that the costs of the individual battery cells, based on their energy content, are reduced as much as possible.

At the same time, however, as the energy density of the battery cells or the battery system increases, the need for safety devices increases in order to enable safe operation.

Accordingly, a compromise has to be found between the achievable energy density, costs and safety of the battery system.

In addition, the available space should be occupied as densely as possible with battery cells in order to increase the range of the motor vehicle accordingly.

The object of the invention is to provide a cost-effective battery cell group that is further optimized in terms of its energy density.

The object is achieved according to the invention by a battery cell group comprising a plurality of individual cells, a single cover assembly and a housing, with a plurality of partition walls being arranged within the housing which separate the individual cells from one another within the housing, with all the individual cells being electrically connected to the cover assembly Housing has a longitudinally extending shell and a first side arranged perpendicular to the shell, the length of the shell in the longitudinal direction being greater than the width of the first side transverse to the longitudinal direction, and wherein the cover assembly is arranged on the first side of the housing.

A basic idea of the invention is to select the geometry and the structure of the battery cell group in such a way that at the same time an optimum is achieved between utilized installation space, achievable energy density and reliable safety function.

Each battery cell of a battery system usually has its own cover assembly, each of which requires a certain amount of installation space that is not available for increasing the energy density of the battery cell.

The electrochemical cell known from the prior art, which has its own battery cell housing and its own cover assembly, is referred to here and below as the battery cell. The battery cell housing of the individual battery cell is typically used to mechanically stabilize the respective battery cell. The cover assembly also usually has conductor lugs with which the battery cell is connected to a cell contact system. In addition, there are safety-relevant elements on the cover assembly, for example a bursting membrane, also known as a safety valve or vent. Furthermore, the electrochemical cell in the battery cell is protected from external influences such as water and oxygen. As described in the prior art, a large number of battery cells can be connected to one another via the cell contacting system to form a module of a high-voltage storage system.

In contrast, the term single cell denotes the electrochemical cell according to the invention which does not have its own housing or its own cover. In other words, the individual cells are designed without a housing.

According to the invention, it is provided that these individual cells are inserted into a jointly used housing in order to form the battery cell group.

The battery cell group can accordingly itself form a module of a high-voltage storage unit, or several battery cell groups can be connected to one another to form a module of a high-voltage storage unit.

The use of a single cover assembly makes it possible to optimally utilize the available installation space and at the same time to increase the energy content of the battery cell group.

In the battery cell group according to the invention, the cover assembly can also have the safety devices known from the prior art, for example safety valves, overload devices and / or fuses, in particular fuses.

In addition, the cover assembly can have an opening for adding the electrolyte during manufacture of the battery cell group.

The battery cell group according to the invention also makes it possible to attach the single cover assembly to the first side of the housing of the battery cell group, the length of the jacket being greater than the width of the first side. This results in a form of the battery cell group in which the total height of the housing of the battery cell group can be minimized without having to reduce the energy content.

In principle, the first side and the jacket surfaces of the jacket extend in directions perpendicular to one another.

The first side of the housing corresponds to an end face of the housing, the first side of the housing being open and being closed by the cover assembly in the assembled state of the battery cell group.

The individual cells are separated from one another by the partition walls. The partition walls thus prevent direct contact with the components of the individual cells.

Electrical crosstalk can take place by isolating the individual cells, for example by wrapping the individual cells in separator film and / or the individual cells having an additional layer made of an insulating polymer film, for example made of polyethylene terephthalate (PET).

The partition itself can also be electrically non-conductive and / or have an electrically non-conductive layer which prevents electrical crosstalk to the adjoining individual cell.

In other words, two adjacent individual cells are each separated from one another by only one partition. Since, in contrast to battery cells known from the prior art, the individual cells do not have their own housing, the thickness of the separating material between two adjacent individual cells is thus reduced.

In particular, the partition wall has a thickness which corresponds to less than twice a conventional housing wall of a battery cell.

The individual cells are preferably lithium-ion batteries, particularly preferably lithium-ion secondary batteries.

The individual cells can be made up of stacks and / or jelly rolls. Correspondingly, the individual cells have at least one cathode, at least one anode and at least one separator which is arranged between the cathode and the anode.

All common cathode materials are used as the cathode material. In this respect, the cathode active material LiCoO ₂ , lithium-nickel-cobalt-manganese compounds (known by the abbreviation NCM or NMC), lithium-nickel-cobalt-aluminum oxide (NCA), lithium iron phosphate and other olivine compounds, lithium manganese -Oxide spinel (LMS or LMO) and manganese-rich mixed oxides can be used.

Likewise, all customary anode materials can be used as anode material, for example an anode active material can be selected from the group consisting of lithium metal oxides such as lithium titanium oxide, metal oxides such as Fe ₂ O ₃ , ZnO, ZnFe ₂ O ₄ , Lithium metal, carbonaceous materials such as graphite, synthetic graphite, natural graphite, graphene, mesocarbon, doped carbon, hard carbon, soft carbon, fullerenes and mixtures of silicon and carbon, silicon, silicon oxide, lithium alloys and mixtures thereof.

All customary materials can be used as separators, for example a polymer selected from the group consisting of polyesters, in particular polyethylene terephthalate, polyolefins, in particular polyethylene or polypropylene, polyacrylonitriles, polyvinylidene fluoride, polyvinylidene-hexafluoropropylene, polyetherimide, polyimide, polyether, polyetherketone or mixtures thereof.

Each of the stacks and / or jelly rolls can already have several cathodes and anodes, each of which is separated by means of a separator. Correspondingly, the individual cells can in turn already represent cell stacks.

The housing of the battery cell group can be made of a metal, for example steel or aluminum, or a metal compound.

The cover assembly can have at least one electrical contact for contacting the battery cell group, which contact is provided on the side of the cover assembly opposite to the housing, in particular two electrical contacts. In this respect, the individual cells of the battery cell group can be at least partially electrically contacted via the cover assembly. Since at least one electrical contact is provided on the cover assembly, the battery cell group can be contacted on one of the end faces of the battery cell group. This allows the contact to be made in a correspondingly simple and space-saving manner, since the end faces of the Battery cell group are easily accessible and smaller in area than one of the surfaces of the shell.

In one variant, the individual cells can each have a cathode collector tab and an anode collector tab, which are electrically connected to the cover assembly.

The cathode arrester lug and the anode arrester lug can protrude from these on opposite sides of the individual cells, so that one of the two arrester lugs, for example the cathode arrester lug, protrudes from the individual cells in the direction of the first side of the housing, while the second of the two arrester lugs, For example, the anode arrester lug protrudes from the single cell in the direction of the second side of the housing.

In this case, the second of the two conductor tabs is guided over the entire length of the individual cells in the direction of the cover assembly so that both conductor tabs can be electrically connected to the cover assembly, in particular to the two electrical contacts provided on the cover assembly.

The cathode arrester lug and the anode arrester lug are then each assigned to an electrical contact or connected to it in an electrically conductive manner.

In a further variant, the individual cells can each have a cathode tab and an anode tab, either the cathode tab or the anode tab is electrically connected to the cover assembly and the other tab is electrically connected to the second side of the housing opposite the cover assembly .

Which conductor tabs are connected to the housing depends primarily on the electrochemical stability of the housing material at the resulting potentials.

In particular, in the case of a housing made of steel, the anode tabs are connected to the housing and the cathode tabs are connected to the cover assembly.

If, on the other hand, the housing is made of aluminum, in particular the cathode discharge tabs are connected to the housing and the anode discharge tabs are connected to the cover assembly.

Such an arrangement enables shorter anode tabs or cathode tabs, since the tabs connected to the housing do not have to be guided over the entire length of the individual cells in the direction of the cover assembly.

In such a variant, all individual cells are connected in parallel.

In such a case, a current flows through the metallic or electrically conductive housing, which is also known under the term Can potential.

If the single cell already has several cathodes and anodes, each of these cathodes and anodes can have an arrester lug, which are brought together in the form of a cathode collecting member and an anode collecting member. In this embodiment, the cathode or anode collecting member establishes the electrical connections listed above.

This allows the number of electrical contacts to be reduced, in particular to one electrical contact for all cathodes and one electrical contact for all anodes.

At least one of the individual cells can have a lamination, in particular each of the individual cells. The lamination can be a film or the outside of a jelly roll. The lamination is correspondingly thin-walled, in particular thinner-walled than the partition walls.

The lamination ensures an additional fixation of the individual cells and is particularly advantageous if the individual cell itself is already made up of several cathodes and anodes.

At least one of the partition walls can comprise a thermally insulating material and / or a thermally insulating coating, in particular made of glass fiber, ceramics and / or polymer-ceramic composites.

Thermally insulating partition walls ensure that an increased temperature within an individual cell cannot affect the surrounding individual cells of the battery cell group or only has a slower effect. In other words, thermally insulating partition walls can thermally separate the individual cell that delimits them from the remaining individual cells.

In this way, the entire battery cell group can be prevented or at least delayed even when an individual cell is passed through, so that adequate safety is ensured despite the higher energy density of the battery cell group.

Runaway is understood here as the so-called thermal runaway, i.e. the self-continuing decomposition of the electrochemical cell with a rise in temperature, which can begin as a result of local overheating, for example after a short circuit or mechanical damage to the respective individual cell.

Furthermore, at least one of the partition walls can comprise a thermally conductive material and / or a thermally conductive coating, in particular made of aluminum.

Thermally conductive partition walls ensure that an increased temperature can be distributed particularly well between several individual cells, thus avoiding local overheating. In other words, the thermally conductive partition walls can be used to achieve a more homogeneous temperature distribution over the multiple individual cells. A too high temperature of an individual cell can therefore be avoided, since the corresponding heat can be easily removed.

Such behavior is particularly advantageous during the charging process of the battery cell group, since increased temperatures due to the charging current are to be expected during the charging process.

Accordingly, a targeted combination of thermally insulating and thermally conductive partition walls within the housing is particularly advantageous, since in this way both a sufficient temperature equalization can take place between the individual cells and at the same time the passage of the battery cell group can be prevented.

A combination of a thermally conductive material or a thermally conductive coating and a thermally insulating material or a thermally insulating coating can also be used.

In this case, the partition wall has sandwich structures, for example with a sequence of materials or a coating of aluminum / glass fiber or aluminum / glass fiber / aluminum.

In a preferred variant, the thickness of the partition walls is less than twice the thickness of an outer wall of the housing, in particular less than twice the thickness of a housing of a conventional battery cell.

In this way, compared to a module with several independent battery cells, each of which would have to have its own outer wall, additional installation space can be saved.

In a further variant, the partition walls have a compression layer which can at least partially compensate for changes in volume of the individual cells, such as occur, for example, during charging and discharging processes and due to aging-related expansion of the electrode.

The compression layer is composed in particular of an elastomer.

Such a compression layer can also be combined with the thermally conductive and / or thermally insulating layers as described above.

The compression layer itself can also be thermally insulating or thermally conductive.

In a further variant, the partition walls and any openings to the cover assembly are impermeable to the electrolyte of the individual cells.

In such a configuration, there is no exchange of electrolyte between the individual cells. This makes it possible, among other things, to connect the individual cells of the battery cell group in series.

In the case of a lithium-ion cell as an individual cell, individual battery cell groups can already have a voltage higher than 4.2 V by connecting several individual cells in series.

Furthermore, the battery cell group can have an overall height that is perpendicular to the longitudinal direction, the overall height being predetermined by the housing, which rests directly on the individual cells transversely to the longitudinal direction, in particular the overall height being essentially 100 mm.

The overall height is usually limited by the available installation space, with the available length or width usually being significantly greater than the available height for applications in motor vehicles. The electrical contact on the end face of the battery cell group results in a volume that corresponds more to a cube, whereby the volume available for the individual cells is maximized. In other words, the fill factor can be increased.

The height of the individual cells therefore essentially corresponds to that of the housing.

Accordingly, the battery cell group according to the invention can utilize the available installation space in a particularly effective manner, as a result of which an overall higher energy density of the built-in battery storage device, that is to say of the battery cell group, is achieved.

In particular, the individual cells extend (essentially) over the entire length of the housing, that is to say from the first side to the second side of the housing.

• - 1 eine separat dargestellte Einzelzelle sowie eine Anordnung von Einzelzellen für eine erfindungsgemäße Batteriezellgruppe;
• - 2 die Anordnung der Einzelzellen aus 1 in der erfindungsgemäße Batteriezellgruppe in einer teilweisen Explosionsansicht;
• - 3 eine schematische Draufsicht auf eine Batteriezellgruppe;
• - 4a eine schematische Seitenansicht der Batteriezellgruppe aus 2;
• - 4b eine schematische Frontansicht auf die Batteriezellgruppe aus 2; und
• - 5 schematische Draufsichten auf verschiedene Ausführungsformen von Trennwänden der Batteriezellgruppe aus 1.

Further advantages and properties of the invention emerge from the following description and from the figures. In these show:

• - 1 a separately shown single cell and an arrangement of single cells for a battery cell group according to the invention;
• - 2 the arrangement of the individual cells 1 in the battery cell group according to the invention in a partial exploded view;
• - 3rd a schematic plan view of a battery cell group;
• - 4a a schematic side view of the battery cell group 2 ;
• - 4b a schematic front view of the battery cell group 2 ; and
• - 5 schematic top views of various embodiments of partition walls of the battery cell group 1 .

In 1 is a single cell 10 shown the multiple cathodes 12th and multiple anodes 14th having.

Between the cathodes 12th and anodes 14th layers of separators (not shown) are arranged in each case.

In the single cell shown 10 it is a lithium-ion cell.

The single cell 10 is a stack of cathodes in the embodiment shown 12th , Anodes 14th and intermediate separators. The stack extends in the longitudinal direction.

In an alternative embodiment, however, it could also be a so-called jelly roll in which the cathodes 12th who have favourited anodes 14th and the separators in between are rolled up.

In the in 1 The embodiment shown has the single cell 10 three cathodes 12th on. In principle, any number of cathodes can be used 12th per single cell 10 be provided, preferably one to one hundred and fifty cathodes 12th in a single cell 10 available. The single cell 10 has just as many anodes in the present case 14th like cathodes 12th .

In principle, the multiple individual cells 10 also different numbers of cathodes 12th exhibit.

From the single cell 10 Cathode tabs protrude from a first end 15th from the cathodes 12th out, with the cathode tabs 15th to a cathode collecting member 16 are connected by means of which the cathodes 12th can be contacted.

On in the longitudinal direction of the single cell 10 opposite second end of the single cell 10 anode tabs protrude 17th from the anodes 14th out, with the anode tabs 17th to an anode collector member 18th are connected by means of which the anodes 14th can be contacted.

The anode collector link 18th is so long in the embodiment shown that its end over the entire length of the single cell 10 to the first end of the single cell 10 can be performed on which the cathode discharge tabs 15th are provided.

Furthermore, the single cell 10 a lamination 20th on that around the cathodes 12th and anodes 14th is arranged around. The lamination 20th is, for example, a plastic film and is used to mechanically stabilize the individual cell 10 .

In principle, the single cell could 10 however, no lamination either 20th have or the lamination 20th is the outer layer of a jelly roll.

In the illustration below in 1 is an arrangement of several single cells 10 shown, which are arranged adjacent to each other. This is how the single cells are 10 in a battery cell group 22nd arranged in 2 which is referred to below.

The battery cell group 22nd has a housing 24 on, with the housing 24 a jacket extending in the longitudinal direction L. 26th as well as one perpendicular to the mantle 26th arranged first page 28 having the length of the jacket 26th in the longitudinal direction L is greater than the width S of the first side 28 across the longitudinal direction L.

On the first page 28 it is therefore an end face of the battery cell group 22nd , as well as from 2 becomes clear.

Furthermore, the housing 24 , and thereby also the battery cell group 22nd , an overall height H which is perpendicular to the longitudinal direction L and to the width S. The total height H is therefore through the housing 24 given.

As in 2 to see is the first page 28 of the housing 24 open and becomes in the assembled state of the battery cell group 22nd of one Lid assembly 30th closed, which is formed in several parts in the embodiment shown.

On to the lid assembly 30th opposite end of the housing 24 is a second side of the housing 24 , which is designed to be closed. The second side is also an end face of the battery cell group 22nd which is therefore (essentially) parallel to the first side 28 is.

The case 24 is formed in the embodiment shown from a metal, for example aluminum.

Inside the case 24 are several partitions 32 arranged the inside of the housing 24 in several chambers 34 subdivide.

The partitions 32 can be spaced evenly or irregularly within the housing 24 be arranged so that chambers of the same width or of different widths 34 surrender.

The thickness of the partitions 32 is preferably less than twice the thickness of the outer wall of the housing 24 , in particular less than twice the thickness of the outer wall of a conventional battery cell.

Into the chambers 34 become the single cells 10 in the housing 24 used in 1 you can see.

Accordingly, there is between two adjacent individual cells 10 one partition each 32 provided so that the single cells 10 are separated from each other.

In the embodiment shown, the cathode collecting members 16 as well as the anode collector links 18th of all single cells 10 towards the first page 28 of the housing 24 , i.e. to the cover assembly 30th .

There they are connected via a connector 36 , the part of the lid assembly 30th is, electrical with two electrical contacts 38 and 40 the lid assembly 30th contacted that on the to the housing 24 opposite side of the lid assembly 30th and for making electrical contact with the battery cell group 22nd serve.

Alternatively, it can also be provided that the electrical contacts 38 , 40 directly to the cathode collecting links 16 or the anode collecting members 18th are connected.

In other embodiments, the anodes 14th or becomes the anode collecting member 18th directly to the housing 24 connected. The connection can be made by means of laser welding or ultrasonic welding. Such an arrangement has the advantage that the anode discharge tabs 17th or the anode collector member 18th no longer to the cover assembly 30th need to be guided.

When assembled, the lid assembly covers 30th the first page 28 the battery cell group 22nd (essentially completely).

In 3rd Fig. 13 is a schematic plan view of an assembled battery cell group 22nd shown, that is to the plane SL, with the anode collector members 18th in 3rd are only indicated schematically.

The partitions 32 are in the embodiment shown alternately made of a thermally insulating material, in particular made of glass fiber, or a thermally conductive material, in particular made of aluminum.

In this way, on the one hand, an individual cell is prevented from overheating 10 too quickly on other single cells 10 the battery cell group 22nd can spread, while on the other hand sufficient heat conduction is achieved in order to avoid unnecessary local overheating, for example during a charging process.

However, all partitions can also be used, depending on requirements 32 made of a thermally conductive 42 or a thermally non-conductive material 44 be.

It is also possible to have at least one partition 32 from a combination of a thermally conductive material or a thermally conductive coating 42 and a thermally non-conductive material or a thermally conductive coating 44 is constructed.

In addition, at least one partition 32 a compression layer 46 have that compensate for changes in volume of the individual cells 10 serves.

Exemplary combinations of thermally conductive material 42 , thermally insulating material 44 and compression layer 46 are in 5 shown schematically.

When combining thermally conductive material 42 and thermally insulating material 44 and / or a compression layer 46 within a battery cell group 22nd , can be the thickness of the partition 32 also be greater than twice the thickness of the outer wall of the housing 24 . Usually there are between two neighboring single cells 10 either a free space or a compression layer 46 attached to volume expansions of the single cell 10 to enable. Thus, in this embodiment, despite thicker partitions 32 a higher energy density can be achieved.

In 4a Fig. 3 is a schematic side view of the battery cell group 22nd Shown to illustrate an exemplary design, that is, a view of the plane HL.

It can thus be seen that in the embodiment shown for the battery cell group 22nd a total height H of 100 mm is provided, which is (essentially) that of the individual cells 10 is exploited. The length L of the battery cell group 22nd is about 310 mm, the length of the individual cells 10 is approximately 270-280 mm.

In this respect, the individual cells extend 10 over the entire height and over a large part of the length of the battery cell group 22nd , namely over more than 80%, in particular 85%.

In 4b Fig. 3 is a schematic front view of the battery cell group 22nd shown, i.e. on the level SH. The width S of the first page 28 is about 50mm as out 4b emerges.

The housing has accordingly 24 In the embodiment shown, the shape of an elongated, rectangular body on the first side 28 open and by means of the lid assembly 30th is locked.

Such an arrangement is particularly suitable for motor vehicles in which the available installation space, in particular in terms of height, is often limited. Through the battery cell group 22nd In such a case, a particularly good fill factor, that is to say a particularly high proportion of used installation space, can be achieved.

Claims (11)

A battery cell group comprising a plurality of individual cells (10), a single cover assembly (30) and a housing (24), wherein a plurality of partition walls (32) are arranged within the housing (24) which separate the individual cells (10) from one another within the housing (24), wherein all individual cells (10) are electrically connected to the cover assembly (30), the housing (24) having a jacket (26) extending in the longitudinal direction (L) and a first side (28) arranged perpendicular to the jacket (26), the length of the jacket (26) being greater than that in the longitudinal direction (L) the width (S) of the first side (28) transverse to the longitudinal direction (L), and wherein the lid assembly (30) is arranged on the first side (28) of the housing (24). Battery cell group according to Claim 1 , characterized in that the cover assembly (30) has at least one electrical contact (38) for contacting the battery cell group (22), which is provided on the side of the cover assembly (30) opposite to the housing (24), in particular two electrical contacts (38) , 40). Battery cell group according to Claim 1 or 2 , characterized in that the individual cells (10) each have a cathode arrester lug (15) and an anode arrester lug (17), which are electrically connected to the cover assembly (30). Battery cell group according to Claim 1 or 2 , characterized in that the individual cells (10) each have a cathode arrester lug (15) and an anode arrester lug (17), either the cathode arrester lugs (15) or the anode arrester lugs (17) with the cover assembly (30 ) and the respective other conductor tabs (15, 17) are electrically connected to the second side of the housing (24) opposite the cover assembly (30). Battery cell group according to one of the preceding claims, characterized in that at least one individual cell (10) has a lamination (20). Battery cell group according to one of the preceding claims, characterized in that at least one of the partition walls (32) comprises a thermally insulating material (44), in particular made of glass fiber and / or aluminum oxide. Battery cell group according to one of the preceding claims, characterized in that at least one of the partition walls (32) comprises a thermally conductive material (42), in particular made of aluminum. Battery cell group according to one of the preceding claims, characterized in that at least one of the partition walls (32) comprises a compression layer, in particular made of an elastomer. Battery cell group according to one of the preceding claims, characterized in that the thickness of the partition walls (32) is less than twice the thickness of an outer wall of the housing (24). Battery cell group according to one of the preceding claims, characterized in that the partition walls (32) are impermeable to the electrolyte of the individual cells. Battery cell group according to one of the preceding claims, characterized in that the battery cell group (22) has an overall height (H) which is perpendicular to the longitudinal direction (L), the overall height (H) being predetermined by the housing (24) which is transverse to the In the longitudinal direction (L) rests directly on the individual cells (10), in particular the total height (H) being essentially 100 mm.

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