WO2015052006A1

WO2015052006A1 - Battery cell, production method for said battery cell, and battery

Info

Publication number: WO2015052006A1
Application number: PCT/EP2014/070455
Authority: WO
Inventors: Joerg Poehler
Original assignee: Robert Bosch Gmbh
Priority date: 2013-10-07
Filing date: 2014-09-25
Publication date: 2015-04-16
Also published as: DE102013220171A1

Abstract

The invention relates to a battery cell, which comprises a housing, at least one battery roll arranged in the housing, the at least one battery roll being electrically connected to a first connection by means of a first current collector element and to a second connection by means of a second current collector element, wherein the first connection and the second connection are arranged at least partially outside of the housing, and at least one first thermally conductive component, which is arranged between the housing and the first current collector element and is in surface contact with the housing and with the first current collector element in order to increase thermal conduction between the housing and the first current collector element. Furthermore, a second thermally conductive component is preferably provided, which is arranged between the housing and the second current collector element and is in surface contact with the housing and with the second current collector element in order to increase thermal conduction between the housing and the second current collector element. The invention further relates to a production method for such a battery cell and to a battery constructed at least of two such battery cells.

Description

Description Battery cell and manufacturing method for this, as well as battery prior art

The present invention relates to a battery cell, in particular a prismatic lithium ion battery cell, and a method for producing such a battery cell.

Furthermore, the present invention relates to a battery, in particular a lithium-ion battery, with at least two of the battery cells according to the invention.

In various fields of technology, sophisticated rechargeable batteries or battery packs are increasingly being used recently, that is to say a parallel or serial combination of a plurality of individual battery cells into a pack or a so-called module. Applications for such battery cells or of such battery packs or battery modules are, for example, in

To find motor vehicle area for driving an electric motor or an additional electric motor, which may be provided in addition to a conventional internal combustion engine, for example in a hybrid vehicle or the like, as well as in other technical areas, such as stationary equipment, mobile phones, portable

Computers, video cameras or MP3 players. Predestined for a wide range of applications is lithium-ion battery technology, which is sometimes highlighted by its high energy density and extremely low self-discharge. Accordingly, a lithium-ion battery consists of at least one, usually two or more lithium-ion battery cells which have at least one positive and one negative electrode, which can reversibly switch on or off lithium ions. As an example of a lithium ion battery cell commonly used in this case is shown in Fig. 4, a prismatic lithium-ion battery cell 9 of the order 60 ampere hours (Ah) according to the prior art, with a housing 91 with side walls 91 1, 912 and 913, a positive pole 92, a negative pole 93 and an air path 94 for degassing the battery cell 9 after filling the same with an electrolyte. A lithium-ion battery exemplified in FIG. 4 can be operated efficiently only in a specific temperature window. From an operating temperature of 40 ° C upwards, for example, the battery life is significantly reduced.

In contrast, at temperatures of below about 0 ° C, the internal resistance of the battery increases sharply and the performance of the battery decreases continuously with decreasing temperatures. Lithium ion high performance batteries for use in the

Automotive sector are operated, for example, in hybrid powertrains with a very high dynamics. However, the temperature gradient between the individual battery cells in the battery must not exceed 5 to 10 Kelvin. During the short-term peak loads, such as when braking, so the so-called recuperation of braking energy, and when accelerating, the so-called boost support, the battery must provide high performance in a very short time. These short peak loads lead due to the internal resistance to a strong warming of the lithium-ion battery cells. The charging and discharging efficiency is very high at about 95%, yet the resulting waste heat is not negligible. On top of that, in the

Outside temperatures of over 40 ° C can prevail and thus the operation of lithium-ion batteries without cooling in addition to the shorter life may also pose a security risk. A lifetime requirement of ten years is thus not feasible without adequate thermal conditioning of the battery or its battery cells, which is a powerful thermal management, so a sufficient cooling of the battery cells at both low and high

Temperatures required.

In general, it should be said that the heat conduction behaves anisotropically in conventional lithium-ion battery cells such as the prismatic battery cell shown in FIG. 4, which is due to the layer structure of such battery cells which is usually used. FIG. 5 shows a schematic cross section through that shown in FIG

prismatic battery cell 9, in which case four so-called battery cell coils 95, also referred to as battery wraps or jelly rolls, are shown arranged side by side in the housing 91. The basically cylindrical battery wraps 95 are connected to one another at their winding ends 956 by a current collector fork 96 and at an upper side at their winding ends 957 by a current collector fork 97, the current collector fork 96 corresponding to the negative pole 93 and the current collector fork 97 corresponding to the positive pole 92 communicates. In an enlarged view in FIG. 5, a wound layer structure is one of the battery wraps 95 is shown in detail, wherein a battery winding 95 of an anode active material 951, for example of graphite, having disposed therein a negative current conductor 952, for example a copper foil, and a cathode active material 953, for example of a lithium metal oxide, with a positive current conductor arranged therein 954, for example, an aluminum foil is constructed. Between the layers of anode and cathode active material 951, 953, an ion-conducting, but not electronically conductive, separator layer (not shown) is usually provided in each case. A

Cross-sectional width of one of the shown wound active material layers 951, 953 is for example at 60μηι to δθμηη. Depending on the desired capacity, a suitable length of electrode active material is wound up and thus defines the dimensions of a single battery winder 95, wherein a plurality of battery wraps are generally introduced in a battery cell housing, as is the case for example in FIG.

A thermal conductivity along the width direction of the battery cell 9, ie in a horizontal direction in Figure 5 taken along the cross-sectional width of the layers 951, 952, 953, 954 is referred to as A _wheel iaiJeiiyRoii denotes a thermal conductivity along the longitudinal direction of the battery cell 9, thus in a vertical direction in Figure 5 perpendicular to the cross-sectional _{width of} the layers 951, 952, 953, 954 is hereinafter referred to as A _aX iaiJeiiyRoii, wherein a naming of the thermal conductivities A _radi aijeiiyRoii and A _axia ijeiiyRoii based on a radial or axial extent of the cylindrical winding. Looking now at the ratios of the two thermal conductivities in high-energy cells, the heat conduction in the "axial" direction of the cell coil, ie A _a xiaueiiyRoii., About a factor 30 times higher than in the "radial" direction, ie as AradiaiJeiiyRoii- In high-power cells this difference corresponds to only about the factor 15, because with these the

Active material layers 951, 953 thinner and the Stromabieiterschichten 952, 954 thicker. A heat dissipation from the battery cell 9 takes place within the cell 9 through the winding 95 with the lower thermal conductivity A _rad iaijeii _y Roii to the outside, wherein the

Material layers of the coil 95 act as a heat transport medium, then in the side walls 91 1 of the housing 91 and finally, within the side walls 91 1 to the side wall 912 or 913. As an example of this is an exemplary in Figure 5

Heat conduction path L _W poor shown by a black arrow, which conducts heat to the side wall 912. Via the cell wall 912, the heat can then be removed, for example, via a preferably insulated, fluid-flowed cooling plate. Although the preceding embodiments explicitly describe a heat dissipation from the battery cell 9, the named properties are also in the case of a pre-heating the battery cell 9 relevant, as may possibly be necessary at low temperatures.

In order to improve now a heat conduction in the battery cell battery concepts are known from the prior art, in which between the cells, ie between a

Cell wall of a battery cell and an adjacent cell wall of the other battery cell additional thermally conductive plates are provided to support the heat transfer in the axial direction of the battery cells. Alternative, more complex battery concepts use, for example, instead of the heat-conducting plates fluid-flow elements between the individual battery cells of the battery, as they are known, inter alia, a plate heat exchanger. A heat dissipation through the side walls of the

However, the battery cell is generally unfavorable because the heat conduction path changes only in the sidewalls from a vertical direction to a horizontal direction, and then to be dissipated to the sidewalls via cooling or the like. This path is longer and therefore in principle less suitable for current dimensions of prismatic battery cells.

A further alternative design for improved heat dissipation from a battery is known, for example, from WO 2012/139338 A1, in which phase change materials are combined in a lithium-ion battery between the individual battery cells, together with air cooling. However, there is still a need that

Thermal conductivity within a battery cell to improve a simple, inexpensive and superior thermal concept in terms of a

To enable battery module designs.

Disclosure of the invention

In order to solve the above-discussed problems, the present invention provides a battery cell structure having an integral concept for heat dissipation / supply of prismatic battery cells, preferably energy cells based on the lithium-ion technique. The invention is based on the generation of a better heat path within the

Battery cell, thereby enabling a simple, low-cost thermal concept in a module design for battery packs, which shows a better thermal system behavior. More specifically, the present invention provides a battery cell having the features of claim 1 provided for a battery, preferably a lithium-ion battery. Furthermore, with the present invention a

Manufacturing method for the battery cell according to the invention and a battery provided with a battery cell according to the invention. In this case, the battery cell according to the invention has a housing, at least one battery winding arranged in the housing and at least one first thermally conductive component, which is arranged between the housing and a first current collector element and in surface contact with them, to conduct heat between the housing and the first current collector element wherein the battery pack is electrically connected to a first terminal via the first current collector element and to a second terminal via a second current collector element. The first terminal and the second terminal are at least partially disposed outside of the housing to allow loading and unloading of the battery cell. Preferably, the battery cell according to the invention further comprises a second thermally conductive component which is arranged between the housing and the second current collector element and is in surface contact therewith in order to increase a heat conduction between the housing and the second current collector element. The battery cell is here preferably a prismatic lithium-ion battery cell, which further preferably has one or more, more preferably four battery windings arranged therein. The thermally conductive components can

In addition, it may be preferable for the components to be electrically insulating, it being noted that the heat-conducting components may not require an electrically insulating function, for example in the case where the entire housing is connected to the positive electrode

is connected and no electrical insulation on the positive side is necessary.

The term "battery wraps" is a winding arrangement of

Cathode active material layers, anode active material layers, between them

intended separators and negative and positive Stromableitern, preferably in sheet form to understand, also called electrode winding, wherein the above-mentioned components are separated from each other by liquid electrolyte. Optionally, passivation layers may be formed on the surfaces of anode material and cathode material.

The term "pantograph element" is preferably a pantograph fork, also called power fork, or the like to understand that either the negative Current conductor or the positive current collector connects with each other and then connects to the respective terminal, the positive current collector, also called cathode, are preferably formed by a copper foil, and the negative current collector, also called anode, are preferably formed by an aluminum foil. Preferably, the arrangement is carried out with light pressure on the heat-conducting component, so that a contact resistance between the power fork (copper / aluminum), heat-conducting component and the housing wall is minimized.

The term "thermally conductive component" is to be understood as meaning a component, either a component or a mass, which has good thermal conduction properties. <br/> This may preferably be a ceramic component which may be made of aluminum oxide, since this represents a low-cost ceramic according to common market conditions, which has the following three properties: a) electrically insulating, b) thermally sufficiently conductive and c) chemically resistant to the contents of the battery cell, in principle suitable for any ceramic material which has the said three properties to a sufficient extent The ceramic component is the space between the power fork and the respective cell housing wall with a suitable potting compound

pour out. This variant places the same requirements on the casting compound as on the ceramic component described above. Preferred casting compounds for this purpose are

For example, filled with alumina particles plastics or resins that are resistant to the chemical ingredients of the battery cell. Another alternative, which is suitable for cells whose positive pole is connected to the rest of the cell housing, is to insert a thermally conductive aluminum component specifically on the positive power fork, or to make the power fork (material: AI) adapted to perform both functions a) as a heat-conducting component, as described above, and b) fulfilled as a power fork.

Additional advantageous developments of the invention are possible by the features of the dependent claims.

In a preferred embodiment of the invention, each thermally conductive

Component receive the corresponding current collector element at least partially, preferably in a recess which is provided in the heat-conducting component. By receiving the current collector element in the heat-conducting component, a sufficient heat transfer between current collector element and heat-conducting Component to be ensured. Further preferably, each thermally conductive component is introduced into the housing such that it completely covers at least one inner wall surface of the housing. By means of this covering arrangement, sufficient heat transfer between the heat-conducting component and the housing can be ensured in the sense of a surface contact that is as complete as possible, with the aim of improving the thermal connection of the battery wraps to the side walls of the housing of the battery cell. Furthermore, it is preferable to modify the design of the pantograph elements so as to maximize the area to the sidewalls of the housing, but leave a space sufficient for the necessary insulation. This area is then filled with the heat-conducting component.

Further preferably, each battery winding has at least one winding end, which is connected to the first current collector element, and preferably at least one further winding end, which is connected to the second current collector element. It is further preferable that each connection between the coil end and current collector element over the entire length of the contact surface between the coil end and

Current collector element extends, wherein preferably the compound is in the form of a welded joint, the weld further preferably extends over the entire length of the contact surface between the coil end and current collector element.

As a result, the largest possible heat transfer distance between the winding end and the current collector element can be achieved by means of the weld seam as a heat transfer interface. In a special embodiment of the cell with a copper foil and an aluminum foil as a current conductor, which are led out of the cell winding to the power forks, these are therefore to be welded to this with a longest possible weld over the entire length of the power fork. In contrast, according to the prior art in conventional battery cells led out of the battery coil copper and aluminum foils, which correspond to the current collector lead to the cell winding ends fixed to this only selectively with usually three welding points, which is for the current from the battery winding to the connections

or Poland of the battery is usually sufficient sizing.

Furthermore, it is preferred that the housing has a cuboid shape with a plurality of surfaces, wherein at least one of the surfaces is provided with a protruding structure. The protruding structure stands on the at least one surface and may have at least one cooling fin or at least one cooling fin or the like. Thus, a compact battery module design can be made possible with effective air cooling, wherein the module assembly can be provided with a suitable insulation, such as an insulating film or an insulating varnish or the like, which are to be applied to the structure.

In a further preferred embodiment of the battery cell according to the invention, a heat-conducting coating is provided at least on one of the heat-conducting components, wherein preferably a further heat-conducting coating is provided on at least one of the current collector elements. By such a heat-conductive coating, a heat transfer between the heat-conducting component and the respective current collector element or between current collector and the respective winding end can be improved, the heat-conductive coating can be a thermal paste or the like.

According to another aspect of the present invention is a

Manufacturing method for a battery cell according to the invention provided as described above. The manufacturing method according to the invention in this case has the step of providing the battery cell housing with the protruding structure, the step of arranging the at least one battery coil together with the at least one first thermally conductive component and the first

Current collector element and with the at least one second heat-conducting

Component and the second current collector element in the housing, the step of closing the battery cell housing, preferably by rapidly welding the housing, and the step of filling electrolyte in the housing. This can ensure that the battery cell housing, also called cell scan, is already provided with the protruding structure before it is filled with the battery wraps and the electrolyte, so that this production step is performed, for example, by a

appropriate welding process can be carried out at which the cell housing may heat again. This warming, if it occurred after filling the housing, could damage the cell chemistry or could possibly lead to the destruction of the cell. Heating of the cell housing before filling the housing with Batteriewickeln and electrolyte is harmless. In the following, possibilities are explained how the now possible concepts for heat dissipation in the battery module can be implemented technically. According to a further aspect of the invention, therefore, a battery is provided which comprises at least two of the

At least one cooling plate is preferably arranged on at least one side wall of the respective battery cells, which is provided on its inside with a thermally conductive component. The

Cooling plate can be a fluid-flowed cooling plate, a heat sink, a so-called heat pipe or the like. On a suitable isolation of the cells in the

Battery module with each other and optionally with respect to the cooling elements in

Module composite is analogous to pay attention to already known battery cooling concepts, including paint, film, thin plastic layers, etc ..

The arrangement of a ceramic element or a potting compound filled with ceramic particles in combination with an adapted current collector fork design and a thermally suitably dimensioned connection of the cell winding ends with the current forks enables a battery cell design optimized for system vision to be achieved for high-energy cells. This new cell design provides the basis for holistic, cost-effective and in comparison to the state of the art improved concepts for heating / warming up the

Battery cell on module or battery pack level. In addition, with the improved thermal management of the battery cell, the life of all

Battery components further increased and the safety of the battery can be increased. Brief description of the drawings

Figure 1 is a schematic sectional view through an inventive

Battery cell according to a preferred embodiment, as well as a

Detailed view of a connection region between the battery cell housing and the battery winding of the battery cell according to the invention;

FIG. 2 is a perspective view of a thermally conductive ceramic member of FIG

Figure 1 illustrated battery cell according to the invention; Figure 3 is a perspective view of a battery having a plurality of the battery cell according to the invention shown in Figure 1;

FIG. 4 is a perspective view of a battery cell according to the prior art

Technology; and

FIG. 5 is a schematic sectional view through that shown in FIG

Battery cell according to the prior art, as well as a detailed view of a layer structure of a battery of the battery cell battery according to the state of

Technology.

Preferred embodiment of the invention

1 shows a battery cell according to a preferred embodiment of the invention in a schematic sectional view from above. The battery cell has one

Housing 1 with two large side walls 1 1, 1 1, a side wall 12 and a side wall 13, which is opposite to the side wall 12. In the housing 1 are

four battery wraps 2 arranged side by side. Each battery wrap 2 has at its one end a battery wrap end 21 and at its end to the battery wrap end 21

opposite end of a battery winding end 22, wherein the battery winding ends 21, 22 are led out of the battery coil copper and aluminum foils, as

Current arresters serve. The battery winding ends 21 of the battery wraps 2 are connected to each other by a pantograph fork 3 acting as a current collector, and the battery winding ends 22 of the battery windings 2 are interconnected by a pantograph fork 4 acting as a pantograph element, the pantograph forks 3, 4 being completely housed in the housing 1. The current collector forks 3, 4 are each connected to a corresponding terminal of the battery cell, which is not shown, but correspond to the terminals 92, 93 shown in Figure 4. As can be seen from the detail view in FIG. 1, each pantograph fork 4, which is representative of all pantograph forks 3, 4, has in cross-section a U-shaped main body 41 with preferably bent ends 42 at right angles, the winding ends 22 abutting an outer side of the main body 41 are welded over its entire length, so that a continuous as possible

Heat transfer contact area between the main body 41 and the winding ends 22nd comes about. In the preferred embodiment is a pantograph fork 4 with two of the coil ends 22 and thus with two of the four coils 2 in parallel electrical and thermal connection. The material of the corresponding pantograph fork 3, 4 corresponds to the material of the winding ends 21, 22 connected thereto. In the case shown here in detail, therefore, the pantograph fork 4 is made of copper and is connected to the coil ends 22 made of copper.

As can still be seen in FIG. 1, the bent ends 42 are the

Pantograph fork 4 received in a ceramic element 6 acting as a heat-conducting component, which is shown in Figure 2 in a perspective view. The

Bent ends 42 are in recesses 61 in the ceramic element. 6

taken, each representing a depression in the ceramic element 6, which corresponds to the geometry of the bent ends 42. The ceramic element 6 further has an overall shape, which preferably applies without gaps to the inside of the housing 1 in the region of the side wall 13 in order to allow the most uniform and large-area heat transfer between the ceramic element 6 and the housing side wall 13. The arrangement is carried out with slight pressure on the ceramic element 6, so that a contact resistance between pantograph fork 4, ceramic element 6 and

Housing side wall 13 is minimized. Corresponding to the ceramic element 6, a comparable ceramic element 5 is arranged on the opposite side of the battery winding 2, which connects thermally between the current collector fork 3 and the inside of the housing 1 in the region of the side wall 12. In Figure 1 is similar to Figure 5 has a thermal conductivity along the width direction of the respective battery cell, so in a horizontal direction in Figure 1 indicates as a _ra diaueiiyRoii, a thermal conductivity along the longitudinal direction of the battery cell, thus in a vertical direction in Figure 1 is as

AaxiaueiiyRoii denotes, wherein a naming of the thermal conductivities A ... _Je iiyRoii based on an extension of the battery wraps 2. Due to the improved heat transfer between the coil ends 21 and the side wall 12 of the housing 1 by means of

Ceramic member 5, a heat conduction between the battery coils 2 and the side wall 12 can be increased, and by the improved heat transfer between the coil ends 22 and the side wall 13 of the housing 1 by means of the ceramic member 6, a heat conduction between the battery coils 2 and the side wall 13 can be increased. The core of the invention according to the preferred embodiment is therefore in the ceramic element 5, 6, which in an alternative embodiment as. can be executed with ceramic particles filled potting compound, in combination with a customized design the current collector forks 3, 4 and the thermally suitably dimensioned connection of the cell winding ends 21, 22 with the current collector forks 3, 4. The aim is a very good thermal connection of the battery coils 2 on the respective side wall 12 and 13 of the cell housing. 1

In Figure 3, a battery 8 is further shown in a perspective view, which is composed of a plurality of prismatic battery cells according to the preferred embodiment described above, wherein the cuboid

Battery cell housing 1 of the battery cells are arranged side by side, so that the respective side walls 12, 13 form a continuous side wall of the battery. In order now to improve heat supply / removal from the side walls 12, 13 of the battery cell housing 1, heat conducting plates 81, preferably fluid-flowed heat-conducting plate 81 are attached to the side walls 12, 13, which still provide the improved heat supply / discharge concept of the individual battery cells on the battery level improve further.

Claims

Claims 1. Battery cell with

a housing (1),

at least one battery winding (2) arranged in the housing (1), which has a first current collector element (3) with a first terminal and a second current collector element (3)

Current collector element (4) is electrically connected to a second terminal, wherein the first terminal and the second terminal are at least partially disposed outside of the housing (1), and

at least one first thermally conductive component (5), which is arranged between the housing (1) and the first current collector element (3) and in surface contact with them in order to conduct heat between the housing (1) and the first

Pantograph element (3) to enlarge, preferably with at least one second thermally conductive component (6) between the housing (1) and the second

Current collector element (4) is arranged and is in surface contact with these in order to increase a heat conduction between the housing (1) and the second current collector element (4).

2. Battery cell according to claim 1, wherein each thermally conductive component (5, 6) at least partially receives the corresponding current collector element (3, 4), preferably in a recess (61).

3. Battery cell according to claim 1 or 2, wherein each thermally conductive component (5, 6) in the housing (1) is introduced so that it has at least one inner wall surface of the

Completely covers housing (1).

4. battery cell (1) according to any one of the preceding claims, wherein each thermally conductive component (5, 6) is either a ceramic component (5, 6), preferably of alumina, or a Vergussbauteil, preferably of a filled with alumina particles plastic or resin material.

5. Battery cell according to one of the preceding claims, wherein each battery winding (2) has at least one winding end (21) which is connected to the first current collector element (3). is connected, and preferably at least one further winding end (22) which is connected to the second current collector element (4).

6. Battery cell according to claim 5, wherein each connection between the coil end (21, 22) and current collector element (3, 4) over the entire length of the contact surface between the coil end (21, 22) and current collector element (3, 4), preferably the Connection is a welded joint and the weld over the entire length of the contact surface between the coil end (21, 22) and current collector element (3, 4) extends to allow the largest possible heat transfer path between them.

7. Battery cell according to one of the preceding claims, wherein the battery cell is a prismatic lithium-ion battery cell, wherein preferably the battery cell has one or more, more preferably four battery wraps (2).

8. Battery cell according to one of the preceding claims, wherein the housing (1) has a parallelepiped shape with a plurality of surfaces (1 1, 12, 13), wherein at least one of the surfaces (1 1, 12, 13) is provided with a protruding structure, in which

preferably, the projecting structure has at least one cooling fin or at least one cooling fin.

9. Battery cell according to one of the preceding claims, wherein a heat-conductive coating is provided at least on a heat-conducting component (5, 6), wherein preferably a heat-conductive coating on at least one

Current collector element (3, 4) is provided.

10. Battery cell according to claim 9, wherein the heat-conductive coating a

Thermal paste is.

1 1. A manufacturing method of a battery cell according to any one of claims 8 to 10, wherein the manufacturing method comprises at least the following steps:

Providing the housing (1) with the protruding structure, which is preferably connected to the housing (1) by welding,

Arranging the at least one battery pack (2) together with the at least one first thermally conductive component (5) and the first current collector element (3) and with the at least one second thermally conductive component (6) and the second

Current collector element (4) in the housing (1),

Closing the housing (1), preferably by welding, Pouring electrolyte into the housing (1) through a small opening remaining open, and finally closing the cell by closing the small opening through which the electrolyte is filled.

12. Battery (8) with at least two battery cells according to one of claims 1 to 10, wherein preferably at least one cooling plate (81) on at least one side wall (12, 13) of the respective battery cells is arranged, which on its inside with the heat-conducting component ( 5, 6) is provided, wherein further preferably, the cooling plate (81) is a fluid-flow cooling plate.