DE102017207066A1 - Fast discharge device for a battery cell and battery cell - Google Patents

Abstract

The invention relates to a rapid discharge device (20) for a battery cell (2), comprising an activation unit (30) which has a first conductor rail (21), a second conductor rail (22) and an insulation layer (35) for insulating the conductor rails (21, 22 ), wherein the insulating layer (35) between the Stromleitschienen (21, 22) is arranged. The activation unit (30) has at least one main semiconductor switch (41), which can be controlled such that a heating current (Ih) flows through the main semiconductor switch (41). The quick discharge device (20) is designed such that by heating as a result of the heating current (Ih), the first Stromleitschiene (21) and the second Stromleitschiene (22) are electrically connected to each other. The invention also relates to a battery cell (2) comprising a negative terminal (15), a positive terminal (16) and a quick discharge device (20) according to the invention, one of the current conducting rails (21, 22) being connected to the negative terminal (15) and one of the power rails (21, 22) is connected to the positive terminal (16).

Description

The invention relates to a rapid discharge device for a battery cell, which comprises an activation unit which has two Stromleitschienen and an insulating layer for insulating the Stromleitschienen, wherein the insulating layer is disposed between the Stromleitschienen. The invention also relates to a battery cell comprising a quick discharge device according to the invention.

State of the art

Electrical energy can be stored by means of batteries. Batteries convert chemical reaction energy into electrical energy. Here, a distinction is made between primary batteries and secondary batteries. Primary batteries are only functional once, while secondary batteries, also referred to as accumulators, are rechargeable. In particular, so-called lithium-ion battery cells are used in an accumulator. These are characterized among other things by high energy densities, thermal stability and extremely low self-discharge.

Lithium-ion battery cells have a positive electrode, also referred to as a cathode, and a negative electrode, also referred to as an anode. The two electrodes of the electrode unit are electrically connected to poles of the battery cell, which are also referred to as terminals. A voltage supplied by the battery cell can be tapped via the terminals. Furthermore, the battery cell can also be charged via the terminals.

In the event of a fault in the battery cell, such as an internal short circuit between the anode and the cathode, it may be necessary to discharge the battery cell to avoid critical conditions that could lead to overheating and explosion of the battery cell. For this purpose, fast discharge devices are known. Such a quick discharge device is a bridging element, which is connected to the terminals of the battery cell. In normal operation, the quick discharge device is open and electrically isolates the terminals of the battery cell from each other. In the case of a fault, the quick discharge device is activated and then electrically connects the terminals of the battery cell with each other. Then, a discharge current flows through the quick discharge device and the battery cell is discharged.

The documents US 2013/0252039 A1 and DE 10 2012 005 979 B4 disclose an electrical bridging element for bridging a battery cell of an electrical energy store. The bridging element comprises two electrical Stromleitschienen and a layer sequence arranged therebetween. The layer sequence has two solder layers, each of which adjoins one of the current conductor rails, two insulation layers, which are arranged between the solder layers, and a reactive layer stack, which is arranged between the insulation layers. When the reactive layer stack is activated, an exothermic reaction takes place and the insulation layers are decomposed. As a result, the electrically conductive solder layers come into contact with each other and thus the Stromleitschienen are electrically connected.

The document US 2006/0102982 A1 discloses an antifuse structure having an integrated heating element. The antifuse structure comprises two conductors and a dielectric layer disposed therebetween. The integrated heating element is configured as an additional current conductor and serves for heating the dielectric layer.

Disclosure of the invention

A quick discharge device for a battery cell is proposed. The quick discharge device comprises an activation unit, which has a first Stromleitschiene, a second Stromleitschiene and an insulating layer for electrically insulating the Stromleitschienen. The insulation layer is arranged between the Stromleitschienen.

The Stromleitschienen the activation unit can be connected to terminals of a battery cell. In a passive state, the quick discharge device is turned off and the power rails are electrically isolated from each other by the insulating layer.

According to the invention, the activation unit has at least one main semiconductor switch, which can be controlled such that a heating current flows through the main semiconductor switch. The quick discharge device is designed such that the first Stromleitschiene and the second Stromleitschiene are electrically connected to each other by heating due to the heating current. Preferably, the insulating layer is configured such that the insulating layer is at least partially decomposed by heating due to the heating current.

When the insulation layer is decomposed, an electrical connection is created between the power rails of the activation unit and the quick discharge device is in an active state. In the active state, the quick discharge is switched on and forms a Short circuit between the terminals of the battery cell, which are connected to the Stromleitschienen the activation unit. Then, a discharge current flows through the quick discharge device and the battery cell is discharged.

Advantageously, a force presses the first conductor rail and the second conductor rail against the insulating layer, or toward each other. When the insulating layer is decomposed, said force causes the first power rail to come into contact with the second power rail. This creates the electrical short circuit between the power rails and between the terminals. Thus, the quick discharge device is in the active state.

According to an advantageous embodiment of the invention, the main semiconductor switch is designed and coupled to the insulating layer, that the main semiconductor switch is heated by the heating current, and that the heated main semiconductor switch, the insulating layer heated so that the insulating layer is at least partially decomposed.

According to an advantageous development of the invention, the main semiconductor switch is electrically connected to the power conducting rails such that the heating current flows through the power conducting rails. The heating current thus flows between the terminals of the battery cell, which are connected to the Stromleitschienen the activation unit. The heating current is thus supplied by the battery cell itself.

According to a further advantageous embodiment of the invention, the activation unit has at least one auxiliary semiconductor switch which can be controlled and arranged such that the heating current flows through the auxiliary semiconductor switch. By means of the auxiliary semiconductor switch diagnostic functions of the activation unit can be realized.

There is a reference point between the main semiconductor switch and the auxiliary semiconductor switch. By alternately switching the main semiconductor switch and the auxiliary semiconductor switch and measuring a voltage at the reference point, a correct function of both semiconductor switches can be checked.

Preferably, the main semiconductor switch and the auxiliary semiconductor switch are electrically connected in series. In this case, for example, the main semiconductor switch is connected to the second Stromleitschiene and the auxiliary semiconductor switch is connected to the first Stromleitschiene. To activate the quick discharge device thus the main semiconductor switch and the auxiliary semiconductor switch must be controlled simultaneously.

Advantageously, the main semiconductor switch and / or the auxiliary semiconductor switch are configured as a MOSFET, that is to say as a metal oxide semiconductor field-effect transistor. The semiconductor switches are thus controlled with a relatively low power. In this case, the main semiconductor switch is designed, for example, as a PMOS type, and the auxiliary semiconductor switch is designed, for example, as an NMOS type.

Other types of semiconductor switches that can produce a low-resistance connection can be used. For example, bipolar transistors and NMOS semiconductor switches are also applicable. The semiconductor switches are both designed as a "normally-off" type.

According to a further advantageous embodiment of the invention, the quick discharge device also has a control unit. The activation unit is connected to the control unit, and the Hauptdarbleiterschalter is controlled by the control unit. Likewise, the auxiliary semiconductor switch can be controlled by the control unit.

The control unit preferably has an application-specific integrated circuit. Such an application-specific integrated circuit is also referred to as ASIC. The application-specific integrated circuit is specially adapted to the requirements in the quick discharge device and designed accordingly.

A battery cell is also proposed which comprises a negative terminal, a positive terminal and a quick discharge device according to the invention. In this case, one of the two Stromleitschienen, for example, the first Stromleitschiene, connected to the negative terminal, and one of the two Stromleitschienen, for example, the second Stromleitschiene is connected to the positive terminal.

The terminals are in particular electrically connected to the Stromleitschienen that the heating current of the battery cell itself is supplied and the Stromleitschienen flows through.

A battery cell according to the invention advantageously finds use in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV), or in a consumer electronics product. Consumer electronics products are in particular mobile phones, tablet PCs or notebooks. Other applications for a battery cell according to the invention are conceivable.

Advantages of the invention

To activate the rapid discharge device according to the invention only a relatively low power is required. In particular, in order to activate the quick discharge device according to the invention, no high current and no high voltage must be supplied by an external control device. This results in a saving of costs and space, especially in an external control device. But also the quick discharge device according to the invention is inexpensive to produce and only requires a relatively small space. In particular, only the insulation layer between the Stromleitschienen must be arranged. As a result, the mechanical complexity in the production of the activation unit is reduced. Furthermore, when the quick discharge device has two series-connected semiconductor switches, the electromagnetic compatibility of the quick discharge device is increased. An unwanted activation of the quick discharge device can only take place if both semiconductor switches are activated simultaneously by an interference signal. By means of the application-specific integrated circuit, the control unit can be specially adapted to the requirements in the quick discharge device and designed accordingly.

list of figures

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

• 1 eine schematische Darstellung eines Batteriemoduls mit mehreren Batteriezellen,
• 2 eine schematische Darstellung einer Batteriezelle und
• 3 eine schematische Schnittdarstellung durch eine Aktivierungseinheit.

Show it:

• 1 a schematic representation of a battery module with multiple battery cells,
• 2 a schematic representation of a battery cell and
• 3 a schematic sectional view through an activation unit.

Embodiments of the invention

In the following description of the embodiments of the invention, the same or similar elements are denoted by the same reference numerals, wherein a repeated description of these elements is dispensed with in individual cases. The figures illustrate the subject matter of the invention only schematically.

1 shows a schematic representation of a battery module 5 with several battery cells 2 , The battery cells 2 are connected in series. Every battery cell 2 includes an electrode unit 10 , which each have an anode 11 and a cathode 12 having. The anode 11 the electrode unit 10 is doing it with a negative terminal 15 connected. The cathode 12 the electrode unit 10 is with a positive terminal 16 connected. For serial connection of the battery module 5 is the negative terminal 15 a battery cell 2 with the positive terminal 16 the adjacent battery cell 2 electrically connected.

Every battery cell 2 also has a quick discharge device 20 on. The quick unloading device 20 is with the negative terminal 15 as well as with the positive terminal 16 the battery cell 2 electrically connected. The quick unloading device 20 is switched off in the illustration shown here, ie in a passive state. That means the negative terminal 15 and the positive terminal 16 the battery cell 2 are through the quick discharge device 20 not electrically connected.

In case of a fault in the battery cell 2 can the fast discharge device 20 to be activated. After activation, the quick discharge device is located 20 in an active state, in which the fast discharge device 20 a short circuit between the negative terminal 15 and the positive terminal 16 forms. Thereupon, a discharge current flows through the quick discharge device 20 and the battery cell 2 is discharged by it.

2 shows a schematic representation of a battery cell 2 , As already out 1 known, includes the battery cell 2 an electrode unit 10 , a negative terminal 15 , a positive terminal 16 and a quick discharge device 20 , The quick unloading device 20 is electrically connected to the negative terminal 15 and the positive terminal 16 connected. The quick unloading device 20 includes an activation unit 30 and a control unit 50 ,

The activation unit 30 has a first Stromleitschiene 21 , a second power rail 22 and an insulation layer 35 on. The first conductor rail 21 is electric with the negative terminal 15 connected. The second power rail 22 is electric with the positive terminal 16 connected. The insulation layer 35 is between the first power rail 21 and the second power rail 22 arranged. The insulation layer 35 thus isolates the first Stromleitschiene 21 and the second power rail 22 from each other. Thus, the power rails 21 . 22 isolated from each other, and the terminals 15 . 16 are electrically isolated from each other.

The activation unit 30 also has a main semiconductor switch 41 and an auxiliary semiconductor switch 42 on. The main semiconductor switch 41 and the auxiliary semiconductor switch 42 are serial interconnected with each other. The main semiconductor switch 41 is with the second power rail 22 electrically connected. The auxiliary semiconductor switch 42 is with the first power rail 21 electrically connected. Thus, the main semiconductor switch 41 and the auxiliary semiconductor switch 42 a series connection, which to the power rails 21 . 22 is connected, and which parallel to the insulation layer 35 is switched.

The activation unit 30 also has a first connection point 31 which is connected to a control input of the main semiconductor switch 41 electrically connected. Likewise, the activation unit 30 a second connection point 32 on, with a control input of the auxiliary semiconductor switch 42 connected is. The activation unit 30 also has a third connection point 33 on that with a reference point 43 electrically connected. The reference point 43 is located on the electrical connection between the main semiconductor switch 41 and the auxiliary semiconductor switch 42 ,

The control unit 50 includes an application specific integrated circuit 55 , Such an application-specific integrated circuit 55 is also referred to as ASIC. The control unit 50 includes a first connection point 51 , which by means of a line to the first connection point 31 the activation unit 30 connected is. Also includes the control unit 50 a second connection point 52 , which with the second connection point 32 the activation unit 30 connected is. Furthermore, the control unit comprises 50 a third connection point 53 that with the third connection point 33 the activation unit 30 connected is. The connection points 51 . 52 . 53 are also available with the application specific integrated circuit 55 connected. The control unit 50 is also by means of a negative supply line 25 with the negative terminal 15 connected. Also, the control unit 50 by means of a positive supply line 26 with the positive terminal 16 connected.

In the illustration shown here is the quick discharge device 20 switched off and the power rails 21 . 22 are electrically isolated from each other. To activate the quick discharge device 20 gives the application specific integrated circuit 55 the control unit 50 a corresponding signal via the first connection point 51 and the first connection point 31 to the control input of the main semiconductor switch 41 , At the same time there is the application-specific integrated circuit 55 the control unit 50 over the second connection point 52 and the second connection point 32 a corresponding signal to the control input of the auxiliary semiconductor switch 42 ,

Through this control by the control unit 50 become the main semiconductor switch 41 and the auxiliary semiconductor switch 42 closed and thus form a short circuit between the first Stromleitschiene 21 and the second power rail 22 and thus between the negative terminal 15 and the positive terminal 16 , As a result, a heating current Ih flows through the main semiconductor switches 41 . 42 ,

Due to the heating current Ih, the activation unit is heated 30 , The heating of the activation unit 30 requires in particular a heating of the insulation layer 35 , This heating causes decomposition of the insulation layer 35 , which thereby at least partially, in particular almost almost completely dissolves. After the insulation layer 35 is decomposed, there is an electrical contact between the first Stromleitschiene 21 and the second power rail 22 , Thus, there is also a short circuit between the negative terminal 15 and the positive terminal 16 ,

The quick unloading device 20 is thus switched on and is in an active state. A discharge current flows through the activation unit 30 the quick-discharger 20 and the battery cell 2 is discharged by the said discharge current.

3 shows a schematic sectional view through an activation unit 30 a quick discharge device 20 , The insulation layer 35 is, as already mentioned, between the first Stromleitschiene 21 and the second power rail 22 arranged. In the illustration shown here is the quick discharge device 20 in a passive state, and the first power rail 21 is by means of the insulation layer 35 from the second power rail 22 electrically isolated.

The insulation layer 35 is designed as a relatively thin polymer film and protrudes from an area between the Stromleitschienen 21 . 22 out. On the insulation layer 35 is the main semiconductor switch 41 applied directly, for example glued. Likewise, the auxiliary semiconductor switch 42 directly on the insulation layer 35 applied, in particular glued. The semiconductor switches 41 . 42 are preferably designed as "bare die". The semiconductor switches 41 . 42 are present of a potting compound 45 Surrounded by the semiconductor switches 41 . 42 almost completely surrounds.

Upon activation of the fast charging device 20 As already mentioned, the heating current Ih flows through the first main holding conductor switch 41 and the second auxiliary semiconductor switch 42 , In this case, in particular, the main semiconductor switch 41 heated. Likewise, the auxiliary semiconductor switch 42 heated. The semiconductor switches 41 . 42 are, as already mentioned, directly on the insulation layer 35 appropriate. The in the semiconductor switches 41 . 42 resulting heat is thus directly on the insulation layer 35 transferred and delivered to this. The insulation layer 35 is designed such that due to the heat input through the semiconductor switches 41 . 42 immediately a decomposition of the insulation layer 35 , for example, by melting occurs.

A force, not shown here presses the first Stromleitschiene 21 and the second power rail 22 against the insulation layer 35 , or towards each other. If the insulation layer 35 decomposed, the said force causes that the first Stromleitschiene 21 in contact with the second power rail 22 comes. This creates the electrical short circuit between the power rails 21 . 22 and between the terminals 15 . 16 , Thus, the quick discharge device is 20 in the active state.

The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2013/0252039 A1 [0005]
• DE 102012005979 B4 [0005]
• US 2006/0102982 A1 [0006]

Claims (11)

A quick discharge device (20) for a battery cell (2), comprising an activation unit (30) having a first Stromleitschiene (21), a second Stromleitschiene (22) and an insulating layer (35) for insulating the Stromleitschienen (21, 22), wherein the insulation layer (35) is arranged between the conductor rails (21, 22), characterized in that the activation unit (30) has at least one main semiconductor switch (41) which can be controlled such that a heating current (Ih) flows through the main semiconductor switch (41) and in that the quick discharge device (20) is designed in such a way that the first conductor bar (21) and the second conductor bar (22) are connected to one another in an electrically conductive manner by heating as a result of the heating current (Ih). Quick Discharge Device (20) after Claim 1 , characterized in that the insulating layer (35) is designed such that the insulating layer (35) is at least partially decomposed by heating due to the heating current (Ih). A quick discharge device (20) according to any one of the preceding claims, characterized in that the main semiconductor switch (41) is configured and coupled to the insulating layer (35) so that the main semiconductor switch (41) is heated by the heating current (Ih) and the heated one Main semiconductor switch (41) heats the insulating layer (35). Quick discharge device (20) according to any one of the preceding claims, characterized in that the main semiconductor switch (41) is electrically connected to the Stromleitschienen (21, 22) such that the heating current (Ih) flows through the Stromleitschienen (21, 22). Quick discharge device (20) according to any one of the preceding claims, characterized in that the activation unit (30) has at least one auxiliary semiconductor switch (42) which is so controlled and arranged that the heating current (Ih) flows through the auxiliary semiconductor switch (42). Quick Discharge Device (20) after Claim 5 , characterized in that the main semiconductor switch (41) and the auxiliary semiconductor switch (42) are electrically connected in series. Quick unloading device (20) according to one of Claims 5 to 6 , characterized in that the main semiconductor switch (41) and / or the auxiliary semiconductor switch (42) are designed as a MOSFET. Quick discharge device (20) according to any one of the preceding claims, characterized in that the activation unit (30) with a control unit (50) is connected, and that the main semiconductor switch (41) by the control unit (50) is controllable. Quick Discharge Device (20) after Claim 8 characterized in that the control unit (50) comprises an application specific integrated circuit (55). Battery cell (2) comprising a negative terminal (15), a positive terminal (16) and a quick discharge device (20) according to any one of the preceding claims, wherein one of the Stromleitschienen (21, 22) with the negative terminal (15) and one of the power rails (21, 22) is connected to the positive terminal (16). Use of a battery cell (2) after Claim 10 in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product.

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