WO2013167721A1

WO2013167721A1 - Battery cell

Info

Publication number: WO2013167721A1
Application number: PCT/EP2013/059697
Authority: WO
Inventors: Matthias Straub; Alexander Reitzle
Original assignee: Robert Bosch Gmbh; Samsung Sdi Co., Ltd.
Priority date: 2012-05-10
Filing date: 2013-05-10
Publication date: 2013-11-14
Also published as: DE102012207804A1

Abstract

The invention relates to a battery cell comprising a dimensionally-stable battery cell housing. The battery cell comprises a pole connection (14) and a conductor (10) which electrically connects said pole connection (14) to a current collector of the battery cell. The invention is characterised in that the conductor forms a safety fuse area (16) with a cavity (12), and a conductor cross-section (20) has a form which surrounds said cavity (12). The conductor cross-section (20) is smaller in the safety fuse area of the cavity (12) than in the adjoining regions of the conductor (10), and as a result said conductor (10) acts as a fuse in the safety fuse area.

Description

description

title

Battery cell The present invention relates to a battery cell with a dimensionally stable

Battery cell housing comprising a pole terminal and a conductor, wherein the conductor electrically connects the pole terminal to a current collector of the battery cell. State of the art

It is becoming apparent that in the future, both in stationary applications, such as wind turbines, in motor vehicles, which are designed as hybrid or electric motor vehicles, as well as electronic devices, such as laptops or mobile phones, new battery systems will be used, to the very high

Requirements with regard to reliability, safety, performance and service life.

In vehicles with at least partial electric drive batteries are used to the electrical energy for the electric motor which the

Drive supports or serves as a drive to save. In the vehicles of the latest generation, so-called lithium-ion batteries can be found here

Use. These are characterized among other things by high energy densities and an extremely low self-discharge. Lithium-ion cells have at least one positive and one negative electrode (cathode or anode), the

Reverse lithium-ion (Li +) on (intercalation) or remove it again

(Deintercalation) can.

Battery cells often have a kind of internal protection mechanism

Fuse that ensures that too much overcurrent will interrupt the flow of current through the battery cell, causing other battery cells to leak Cellular Protected. This type of fuse is mainly used in lithium-ion batteries in the form of a so-called CID (current interrupt device) application.

For example, US 2010/0255351 A1 describes a prismatic one

Battery cell with a flexible battery cell housing, which is realized by a film. The electrical connections to the battery cell are designed as sheet metal strips, wherein an electrical connection has a perforation, so that the pole connection serves as a fuse.

In the case of battery cells with a dimensionally stable battery cell housing (hardcase battery cell housing), it is possible to protect the battery cell by mounting ordinary fuses outside the battery cell in order to force it to switch off. As a rule, however, a fuse is assembled inside the battery cell. A fuse inside an electrochemical cell can be unfavorable when triggered

Voltage distributions (sometimes to a voltage reversal) lead inside the battery cell, which can lead to unwanted subsequent reactions.

Disclosure of the invention

According to the invention, a battery cell with a dimensionally stable

Battery cell housing comprising a pole terminal and a conductor provided, wherein the conductor electrically connects the pole terminal with a current collector of the battery cell. The conductor forms a fuse region with a cavity, wherein a conductor cross-section has a circumferential shape around the cavity and the conductor cross-section in the securing region of the cavity is smaller than in the adjacent regions of the conductor, such that the conductor acts as a fuse in the fuse area.

The conductor can be connected as required to an anode as well as to a cathode of the battery cell.

As described, according to the prior art in prismatic

Battery cells with dimensionally stable battery cell housings (hardcase battery cells) usually arranged a fuse inside the battery cell housing. As a result, an unfavorable potential distribution could hitherto occur due to the triggering of the fuse in the interior of the battery cell, as a result of which unwanted follow-up reactions can be initiated (for example corrosion of the battery cell housing or of a current collector - that part which is electrically conductively connected to one electrode of the battery cell ). The inventive design of a fuse area in the conductor, which connects the pole terminal to the current collector, it is possible, the

Security area z. B. outside the battery cell housing. Preferably, the conductor is part of the current collector, and more preferably, the conductor is integral with the current collector. Furthermore, it is possible by the invention to spatially separate the fuse area of the conductor from a chemically active part of the battery cell. This will be the

Potential distributions inside the battery cell not changed. This results in stable electrochemical conditions and processes while the full functionality and reliability of a fuse is integrated into the battery cell.

As a result of the smaller conductor cross-section in the fuse area compared to the areas adjacent to the fuse area, this results in

Conductor cross-section an increased resistance. With inadmissibly high currents, the conductor heats up so much in the fuse area that the material of the conductor melts in the fuse area and interrupts the current. The fact that the reduction of the conductor cross-section in the fuse area is caused by a cavity and not by a constriction of the conductor, the bending stiffness of the conductor is only slightly reduced compared to a solid body with the same outer diameter.

A sensitivity of the fuse area of the conductor can be set, for example, by the shape design, for example by the length of the fuse area in the conductor direction and the conductor cross section in the fuse area. The conductor preferably has a tubular contour in the securing area. Such structures are inexpensive to manufacture and integrate well into the conductor. Preferably, the conductor is designed in the fuse area, at a

Current> 25% of the short-circuit current of the fully charged battery cell melt. As a result, an impermissibly high current through the battery cell is prevented before the battery cell can heat up too much and the heating causes consequential damage.

A further influencing of the sensitivity of the security area can take place in that the surface of the conductor has a structure and / or texture in the security area. For example, by targeted tapering of the conductor cross-section of the heat flow and the local resistance can be influenced. In the structures, the same structures can be used as in the classical fuses z. B. at

Overcurrent fuses in the household, industrial plants, etc. are introduced. Preferably, the conductor in the fuse area comprises at least one taper of the conductor cross-section. According to another preferred

Embodiment of the invention comprises the conductor in the fuse area in

Conductor direction alternating thickening and rejuvenation of the

Conductor cross-section. The rejuvenations act as heat sources, while the thickenings act as heat sinks. This is a preferred

Melting of the rejuvenation, the function of the fuse thus takes place at a defined location.

Another possibility to adjust the behavior of the fuse area of the conductor is the use of selected materials for the

Security area. For example, the conductor may contain or consist of tungsten, copper, aluminum or silver in the fuse area. Also suitable are alloys such as an alloy of 55% copper, 44% nickel and 1% manganese (known under the brand name Konstantan from ThyssenKrupp). Also suitable are bronzes, particularly preferably tin, zinc or aluminum bronze. These materials can be introduced, for example, as cylinder tubes in the security area and with

adjacent parts of the conductor by means of classical joining techniques such. As laser welding, press-fitting, rivets, etc. are connected. Furthermore, also formations of the conductor in the fuse area by means

Semiconductor elements or conductive ceramics conceivable. Preferably, an extinguishing medium is introduced into the cavity. The extinguishing medium may be in the fuse area during the melting of the conductor pick up and bind forming molten metal. In addition, gaps that result from the melting of the conductor in the fuse area, filled by an entry of the extinguishing medium and thereby arcing arcs are deleted in the gaps. The current flow is thereby interrupted quickly.

The extinguishing medium preferably contains quartz sand. Likewise come

Mixtures of quartz sand with other minerals, eg. As alumina into consideration. The mixtures, and parameters such as grain sizes, etc., are based, among other things, on how fast the current should be interrupted when the conductor melts in the fuse area and how hot the fuse area should be when triggered.

According to a preferred embodiment of the invention, the battery cell is a lithium-ion battery cell (secondary cell). Lithium-ion battery cells are characterized by a high power and energy storage density, resulting in further advantages, especially in the field of electromobility.

Furthermore, a battery comprising a plurality of battery cells according to the invention is provided. The battery cells are connected in parallel and / or in series with each other via their pole terminals.

Furthermore, a motor vehicle with the battery according to the invention is made available, wherein the battery module is generally provided for feeding an electric drive system of the vehicle.

Advantageous developments of the invention are specified in the dependent claims or refer to the description.

drawings

Embodiments of the invention will be explained in more detail with reference to the drawings and the description below. Show it:

FIG. 1 shows a sectional view through a connection region according to a first preferred embodiment, 2 shows a sectional view through a connection region of the battery cell according to a second preferred embodiment, and

3 shows a sectional view through a connection region of the battery cell according to a third preferred embodiment.

FIG. 1 shows a sectional view through a connection region of a

Battery cell according to the invention according to a first preferred

Embodiment. A conductor 10 is through an opening in the battery cell cover 34 (Cap Plate), which forms part of a battery cell housing, from the

Inside the battery cell led to the outside. Outside the

Battery cell housing is the conductor 10 via an electrically conductive

Connection 30 is connected to a pole terminal 14, wherein usually both the conductor 10 and the pole terminal 14 are made of metal. The lower part of the conductor 10 in FIG. 1, which is located inside the battery cell housing, is electrically conductively connected to a current collector of the battery cell.

Preferably, the conductor 10 may also be part of the current collector, and more preferably the conductor 10 is integral with the current collector. In order to prevent an electrically conductive connection between the conductor 10 and the battery cell cover 34, the conductor 10 from

Battery cell cover 34 separated by electrical insulators 32. The conductor 10 forms a securing region 16 with a cavity 12. The cavity 12 may be, for example, a bore in a cylindrical conductor 10, whereby the conductor 10 has a tubular contour in the fuse area. The fuse region 16 has a smaller conductor cross-section 20 (current-carrying surface) over a fuse length 18 compared to the regions of the conductor 10 adjoining the fuse region 16. The conductor cross-section 20 of the securing region 16 shown in the figure denotes an annular conductor cross-section 20, which is delimited by two concentric circles with different radii. The dimension of the conductor cross-section

20 thus shows the difference of the radii of the two concentric circles.

An electrical resistance during a current flow through the conductor 10 is essentially determined by the electrical resistance in the safety area 16 of the conductor 10. The electrical resistance is calculated according to the physical formula: R = p ^* I / A. With R = ohmic resistance of the Fuse area 10, p = resistivity of the used

Material, I = fuse length 18, and A = conductor cross-section 20. The resistivity is a material constant, whereby the electrical resistance of the fuse area for a given material by the fuse length 18 and the conductor cross-section 20 can be adjusted. In the example shown is the

Fuse length 18, the free length of the hollow cylindrical conductor 10, which is not connected to other metallic and thus conductive materials. However, the conductor can be used in conjunction with insulators, for. As plastics or ceramics.

In the event of a short circuit, the total power loss P _Ve riust = 1 ^{2 *} R is converted into heat output P heat = C _p ^* m ^* AT / At. With C _p = specific

Heat capacity, m = mass of the conductor in the fuse area 16, AT =

Temperature difference of the conductor in the fuse area, the upper

Temperature is the melting temperature of the conductor in the fuse area and the lower temperature is the room temperature, At = time until the conductor melts in the fuse area.

Thus, for example, for copper as the conductor material in the fuse area, an AT value of approx. 1330 K. This AT value should be used as the target in

Short circuit case, for example, within 50 ms quasi-adiabatic with the environment at a current flow of 2000 A can be achieved. From these parameters, the fuse length 18 and the conductor cross-section 20 can be determined for the design of the fuse. The formula m = p _m ^* I ^* A, where p _m = density of the conductor material in the fuse area, establishes the relationship between the above-mentioned formulas of the ohmic resistance R and the thermal power P _W.

Figure 2 shows a sectional view through a connection region of a

Battery cell according to the invention according to a second preferred

Embodiment. In contrast to the first shown in Figure 1

Embodiment, the conductor 10 in the fuse portion 16 a

Securing structure 22. For this purpose, the conductor 10 in the fuse area 16 and, for example, over the entire fuse length 18 in the conductor direction include alternating thickening and tapering of the conductor cross-section 20. At inadmissibly high currents through the conductor 10 act the Rejuvenations as heat sources, while the thickenings act as heat sinks, whereby the conductor 10 in the fuse area 16 within the

Rejuvenations begin to melt.

FIG. 3 shows a sectional view through a connection region of a battery cell according to the invention in accordance with a third preferred embodiment

Embodiment. In the cavity 12 is in the fuse area 16 a

Extinguishing medium 26 introduced. So that the extinguishing medium 26 at

Vibration loads or in movements in which the head or the battery cell is stored overhead, does not fall out, the cavity 12 is closed with a closure 28. For extinguishing media 26, which are based on sand, sealing can be carried out by melting the uppermost part of the sand by means of a high-temperature flame. This results in a glass plug which, combined with a corresponding geometric adaptation of the conductor 10, prevents the extinguishing medium 26 from falling out. In FIG. 3, this adaptation of the conductor can be seen as a groove running all around at the level of the closure 28.

Claims

claims

Battery cell with a dimensionally stable battery cell housing comprising a pole terminal (14) and a conductor (10), wherein the conductor (10) the

Pole terminal (14) electrically connected to a current collector of the battery cell, characterized in that the conductor forms a securing region (16) with a cavity (12), a conductor cross-section (20) has a circumferential shape around the cavity (12) and the conductor cross-section ( 20) in the securing region of the cavity (12) is smaller than in the adjacent regions of the conductor (10), such that the conductor (10) acts as a fuse in the fuse area.

Battery cell according to claim 1, wherein the conductor (10) in the securing region (16) has a tubular contour.

Battery cell according to one of the preceding claims, wherein the conductor (10) in the fuse area (16) is designed to melt at a current> 25% of the short-circuit current of the fully charged battery cell.

Battery cell according to one of the preceding claims, wherein the conductor (10) in the securing region (16) at least one taper of the

Conductor cross section includes.

Battery cell according to claim 4, wherein the conductor (10) in the fuse area (16) in the conductor direction comprises alternating thickening and tapering of the conductor cross-section (20).

Battery cell according to one of the preceding claims, wherein in the cavity (12) an extinguishing medium (26) is introduced.

7. Battery cell according to claim 6, wherein the extinguishing medium (26) contains quartz sand.

8. Battery cell according to one of the preceding claims, wherein the battery cell is a lithium-ion battery cell.

9. Battery comprising a plurality of battery cells according to one of the preceding claims.

10. Motor vehicle with a battery according to claim 9.