DE102015215500A1 - Electrode unit for a battery cell, battery cell and method for operating the battery cell - Google Patents

Abstract

The invention relates to an electrode unit (10) for a battery cell, comprising an anode (21) comprising an anodic active material (41) and an anodic current collector (31), and a cathode (22) comprising a cathodic active material (42) and a cathodic current collector (32), and a separator (18) which separates the anode (21) from the cathode (22). In this case, the anodic active material (41) is in the form of strip-shaped anode segments (71, 72), and / or the cathodic active material (42) is in the form of strip-shaped cathode segments (81, 82), the separator (18) being continuous is. The invention also relates to a battery cell comprising such an electrode unit (10) and a method for operating the battery cell, wherein a compensating current flowing from one anode segment (71, 72) to an adjacent anode segment (71, 72) is detected, and / or a compensating current flowing from a cathode segment (81, 82) to an adjacent cathode segment (81, 82) is detected.

Description

The invention relates to an electrode unit for a battery cell, which comprises an anode, a cathode and a separator. The invention also relates to a battery cell, which comprises at least one electrode unit, and to a method for operating the battery cell.

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. A battery comprises one or more battery cells.

In particular, so-called lithium-ion battery cells are used in an accumulator. These are characterized among other things by high energy densities and a low self-discharge. Lithium-ion battery cells are used, inter alia, in motor vehicles, in particular in electric vehicles (EV), hybrid vehicles (HEV) and plug-in hybrid electric vehicles (PHEV).

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 cathode and the anode each comprise a current conductor, on which an active material is applied. The active material for the cathode is, for example, a metal oxide. The active material for the anode is, for example, graphite. But silicon is also used as active material for anodes.

In the active material of the anode lithium atoms are embedded. During operation of the battery cell, ie during a discharge process, electrons flow in an external circuit from the anode to the cathode. Within the battery cell, lithium ions migrate from the anode to the cathode during a discharge process. The lithium ions from the active material of the anode store reversibly, which is also referred to as delithiation. During a charging process of the battery cell, the lithium ions migrate from the cathode to the anode. In this case, the lithium ions reversibly store back into the active material of the anode, which is also referred to as lithiation.

The electrodes of the battery cell are formed like a foil and wound with the interposition of a separator, which separates the anode from the cathode, to an electrode coil. Such an electrode winding is also referred to as a jelly roll. The electrodes can also be stacked to form an electrode stack or in another way form an electrode unit.

The two electrodes of the electrode unit are electrically connected by means of collectors to poles of the battery cell, which are also referred to as terminals. A battery cell usually comprises one or more electrode units. The electrodes and separator are surrounded by a generally liquid electrolyte. The electrolyte is conductive to the lithium ions and allows the transport of lithium ions between the electrodes.

The battery cell further comprises a cell housing, which is made of aluminum, for example. In the case of a design called a prismatic battery cell, the cell housing is prismatic, in particular cuboid, configured and pressure-resistant. The terminals are located outside the cell case. After connecting the electrodes to the terminals, the electrolyte is filled in the cell housing. Other designs, which differ in particular by the design of the cell housing, are widely used, for example, round cells with a cylindrical cell housing and pouch cells with prismatic, mechanically non-pressure-resistant cell housing.

In today's usual configurations of battery systems, several battery cells are combined to form a battery module. Several battery modules form a battery system, which additionally comprises a control unit for monitoring and controlling the battery modules and the battery cells.

A generic battery cell with an electrode unit, which comprises an anode and a cathode, which are separated from a separator, for example, from DE 10 2013 200 714 A1 known.

A battery with multiple battery cells and a method for fault detection in the battery cells are from the US 2013/0113495 A1 known.

In the US 2011/0110183169 A1 discloses a battery cell having a plurality of electrode units, which are arranged in a common housing.

Disclosure of the invention

An electrode unit for a battery cell is proposed, which has an anode, which has an anodic active material and an anodic current collector, and a cathode, which comprising a cathodic active material and a cathodic current collector, and a separator separating the anode from the cathode.

According to the invention, the anodic active material is present in the form of strip-shaped anode segments, and / or the cathodic active material is in the form of strip-shaped cathode segments, while the separator is designed to be continuous.

According to an advantageous embodiment of the invention, the anodic current conductor is formed continuously, and / or the cathodic current collector is formed continuously.

According to another advantageous embodiment of the invention, the anodic current conductor is in the form of strip-shaped Anodenableitersegmenten, and / or the cathodic current conductor is in the form of strip-shaped Kathodenableitersegmenten ago.

Preferably, the Anodenableitersegmente of the anodic Stromableiters are interconnected by connecting webs, and / or the Kathodenabsitere of the cathodic Stromableiters are interconnected by connecting webs.

A battery cell is also proposed which comprises at least one electrode unit according to the invention.

Furthermore, a method for operating a battery cell according to the invention is proposed. In this case, a compensating current flowing from an anode segment to an adjacent anode segment is detected, and / or a compensating current flowing from one cathode segment to an adjacent cathode segment is detected.

According to an advantageous embodiment of the method, a magnetic field is measured, which is generated by the compensating current flowing through a continuously formed anodic current collector, and / or flows through a continuously formed cathodic current collector.

According to another advantageous embodiment of the method, a magnetic field is measured, which is generated by the compensating current flowing through a connecting web, through which Anodenableitersegmente the anodic Stromableiters are interconnected, and / or through which Kathodenableiterable of the cathodic Stromableiters are interconnected.

According to another advantageous embodiment of the method, a voltage applied to a connecting web, by which Anodenableitersegmente of the anodic Stromableiters are interconnected, and / or are connected by which Kathodenableitersegmente the cathodic Stromableiters, voltage applied, which is generated by the compensating current, by the Connecting bar flows.

A battery according to the invention advantageously finds use in a stationary energy store, 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.

Advantages of the invention

An inventively designed electrode unit allows a relatively simple error detection. With an intact electrode unit, currents flow in the same direction through all anode segments as well as through all cathode segments. In the case of a defect in the electrode unit, the defective anode segment or the defective cathode segment has changed electrical properties. As a result, a compensating current flows, for example, from the defective anode segment to an adjacent anode segment or from the defective cathode segment to an adjacent cathode segment. If there is no defect in the electrode unit, there is no or only a small, temporally slowly variable compensation current.

Such a compensating current is therefore an indication of a fault in a battery cell, which can lead to heating of the battery cell to exceeding a critical temperature. In this case, an exothermic reaction of the battery cell, which is also referred to as "thermal runaway" are triggered. As a result, a fire or explosion of the battery cell can take place. If such a fault is detected in good time by detection of the equalizing current in the electrode unit, the battery cell can be switched off in good time and / or further safety measures, in particular a discharging of the battery cell, can be carried out.

A detection of such a compensation current flowing in a different direction than the regular, flowing through the anode segments and through the cathode segments streams is relatively easy to carry out. In particular, a compensating current generates a magnetic field having an orientation different from that of the differs from regular currents generated magnetic fields. Thus, a defect on an electrode unit can be detected early and reliably.

The distinction between a faulty battery cell and a non-defective battery cell, for example, by an electronics in or on the battery cell or at a higher level of integration, for example, in a module electronics done. A classification as a faulty battery cell, for example, takes place when a temporally rapid change in the compensation current and the associated measured variables takes place, or if these quantities increase above a typical limit for a non-defective battery cell.

In addition to the cell monitoring during operation of the battery cell as energy storage in a battery system and a use of the method according to the invention for cell defect testing after manufacture, while transport or storage is possible.

Brief description of the drawings

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

Show it:

1 a schematic representation of a battery cell,

2 a perspective view of an electrode unit of the battery cell 1 .

3 a schematic sectional view of the electrode unit 2 according to a first embodiment,

4 a schematic sectional view of the electrode unit 2 according to a second embodiment,

5 a schematic plan view of the electrode unit 2 according to a third embodiment and

6 a schematic representation of a battery cell with integrated sensor.

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.

A battery cell 2 is in 1 shown schematically. The battery cell 2 includes a cell housing 3 , which in the present case is cuboid, is formed. The cell case 3 In the present case, it is designed to be electrically conductive and, for example, made of aluminum. The cell case 3 but can also be made of an electrically insulating material, such as plastic, and / or be designed in a different design, for example as a round cell or pouch cell.

The battery cell 2 includes a negative terminal 11 and a positive terminal 12 , About the terminals 11 . 12 can one from the battery cell 2 provided voltage can be tapped. Furthermore, the battery cell 2 over the terminals 11 . 12 also be loaded. The terminals 11 . 12 are spaced from each other on a top surface of the prismatic cell housing 3 arranged.

Inside the cell case 3 the battery cell 2 is an electrode unit 10 arranged, which is embodied here as an electrode winding. The electrode unit 10 has two electrodes, namely an anode 21 and a cathode 22 , on. The anode 21 and the cathode 22 are each carried out like a film and with the interposition of a separator 18 wound to the electrode coil. It is also conceivable that several electrode units 10 in the cell case 3 are provided. Instead of an electrode winding, the electrode unit 10 also be designed for example as an electrode stack.

The anode 21 includes an anodic active material 41 , which is designed like a film. The anodic active material 41 has, for example, as raw material graphite or silicon or an alloy containing these substances. The anode 21 further includes an anodic current collector 31 , which is also formed like a film. The anodic active material 41 and the anodic current collector 31 are laid flat against each other and connected to each other.

The anodic current conductor 31 is made electrically conductive and made of a metal, such as copper. The anodic current conductor 31 is by means of a collector 52 electrically with the negative terminal 11 the battery cell 2 connected.

The cathode 22 comprises a cathodic active material 42 , which is designed like a film. The cathodic active material 42 has as a base material, for example, a metal oxide. The cathode 22 further includes a cathodic current collector 32 , which is also formed like a film. The cathodic active material 42 and the cathodic current conductor 32 are laid flat against each other and connected to each other.

The cathodic current conductor 32 is made electrically conductive and made of a metal, such as aluminum. The cathodic current conductor 32 is by means of a collector 52 electrically with the positive terminal 12 the battery cell 2 connected.

The anode 21 and the cathode 22 are through the separator 18 separated from each other. The separator 18 is also formed like a film. The separator 18 is electrically insulating, but ionically conductive, so permeable to lithium ions.

The cell case 3 the battery cell 2 is with an electrolyte 15 , For example, a liquid electrolyte or with a polymer electrolyte filled. The electrolyte 15 surrounds the anode 21 , the cathode 22 and the separator 18 , Also the electrolyte 15 is ionic conductive.

2 shows a perspective view of the electrode unit 10 the battery cell 2 out 1 , The electrode unit 10 is, as already mentioned, in the present case designed as an electrode winding. The anode 21 , the cathode not visible in this illustration 22 and the separator 18 are wound around a winding axis A to the electrode winding.

The anode 21 includes an anodic current collector 31 and an anodic active material 41 , The anodic active material 41 comprises a first strip-shaped anode segment 71 and at least one second strip-shaped anode segment 72 , The strip-shaped anode segments 71 . 72 lie parallel to each other on the anodic current collector 31 on. The strip-shaped anode segments 71 . 72 are separated from each other. It is also possible to provide further strip-shaped anode segments. The separator 18 is continuous, integrally formed.

3 shows a schematic sectional view of the electrode unit 10 out 2 according to a first embodiment. The anodic current conductor 31 is continuous, integrally formed. The at least two strip-shaped anode segments 71 . 72 lie parallel to each other on the continuous anodic current conductor 31 on and are separated from each other.

The cathode 22 is similar to the anode 21 and comprises a cathodic active material 42 , which is a first strip-shaped cathode segment 81 and at least one second strip-shaped cathode segment 82 includes. The strip-shaped cathode segments 81 . 82 lie parallel to each other on the cathodic current collector 32 on, which is continuous, integrally formed. It is also possible to provide further strip-shaped cathode segments.

Furthermore, the at least two strip-shaped anode segments are located 71 . 72 and the at least two strip-shaped cathode segments 81 . 82 on the continuous, one-piece separator 18 ,

In a modification of the first embodiment of the electrode unit 10 could be the anodic active material 41 or the cathodic active material 42 also be continuous, integrally formed.

4 shows a schematic sectional view of the electrode unit 10 out 2 according to a second embodiment. The anodic current conductor 31 comprises a first strip-shaped Anodenableitersegment 76 and at least one second anode drain segment 77 which are parallel to each other and separated from each other. It is also possible to provide further strip-shaped anode drainage segments.

The first strip-shaped anode segment 71 lies on the first strip-shaped Anodenableitersegment 76 on. The second strip-shaped anode segment 72 lies on the second strip-shaped Anodenableitersegment 77 on. It is also possible for further strip-shaped anode segments to rest on further anode drainage segments.

The cathode 22 is similar to the anode 21 and comprises a cathodic active material 42 , which is a first strip-shaped cathode segment 81 and a second strip-shaped cathode segment 82 includes. It is also possible to provide further strip-shaped cathode segments. The cathodic current conductor 32 comprises a first strip-shaped cathode drainage segment 86 and a second cathode drain segment 87 which are parallel to each other and separated from each other. There may also be provided further strip-shaped Kathodenableitersegmente.

The first strip-shaped cathode segment 81 lies on the first strip-shaped Kathodenableitersegment 86 on. The second strip-shaped cathode segment 82 lies on the second strip-shaped Kathodenableitersegment 87 on. It is also possible for further strip-shaped cathode segments to rest on further cathode drainage segments.

Furthermore, the strip-shaped anode segments lie 71 . 72 and the strip-shaped cathode segments 81 . 82 on the continuous, one-piece separator 18 ,

In a modification of the second embodiment of the electrode unit 10 could be the anodic current collector 31 or the cathodic current conductor 32 also be continuous, integrally formed.

5 shows a schematic plan view of the electrode unit 10 out 2 according to a third embodiment. The electrode unit 10 according to the third embodiment, the in 4 shown electrode unit 10 according to the second embodiment.

Unlike the in 4 shown electrode unit 10 According to the second embodiment, the first anode drain segment 76 and the second anode drain segment 77 of the anodic current collector 31 through connecting bridges 90 connected with each other. Likewise, the first Kathodenableitersegment not visible in this illustration 86 and the second Kathodenableitersegment not visible in this illustration 87 of the cathodic Stromableiters not visible in this representation 32 by not visible in this representation connecting webs 90 connected with each other.

In a modification of the third embodiment of the electrode unit 10 could the connecting bridges 90 of the anodic current collector 31 or the connecting webs 90 of the cathodic current conductor 32 also omitted. In a further modification of the third embodiment of the electrode unit 10 could be the anodic current collector 31 or the cathodic current conductor 32 also be continuous, integrally formed.

In case of a defect, for example the first anode segment 71 , flows a compensation current Ia, for example, from the defective first anode segment 71 to the adjacent second anode segment 72 through at least one of the connecting webs 90 , In the present case, the compensating current Ia flows parallel to the winding axis A of the electrode unit designed as an electrode winding 10 , In periods when the battery cell 2 is neither charged nor discharged, these equalizing currents Ia directly indicate the presence of a cell error. In the case of discharging or charging the battery cell 2 the regular ones flow through the anode segments 71 . 72 flowing currents in a direction other than the compensating current Ia, in the present case approximately at right angles thereto.

Thus, the compensating current Ia generates a magnetic field having an orientation different from that of the magnetic fields, that of the regular ones, through the anode segments 71 . 72 flowing currents, deviates.

In case of a defect, for example the first cathode segment 81 , flows a compensation current Ia, for example, from the defective first cathode segment 81 to the adjacent second cathode segment 82 through at least one of the connecting webs 90 , In the present case, the compensating current Ia flows parallel to the winding axis A of the electrode unit designed as an electrode winding 10 , The regular, through the cathode segments 81 . 82 flowing streams flow around the winding axis A in this embodiment. Thus, the regular, through the cathode segments flow 81 . 82 flowing currents in a direction other than the compensating current Ia, in the present case approximately at right angles thereto.

Thus, the equalizing current Ia generates a magnetic field having an orientation different from that of the magnetic fields, that of the regular ones, through the cathode segments 81 . 82 flowing currents, deviates.

A detection of the compensating current Ia is possible by detecting the magnetic field generated by the compensating current Ia. In 6 is a battery cell 2 with an integrated sensor 50 shown schematically for detecting a magnetic field.

The electrode unit designed as an electrode winding 10 is in the cell case 3 arranged such that the winding axis A extends in a direction which is parallel to a connecting line between the negative terminal 11 and the positive terminal 12 extends.

The anodic current conductor, not shown 31 is by means of a collector 52 with the negative terminal 11 connected. The cathodic current conductor, not shown 32 is by means of a collector 52 with the positive terminal 12 connected.

The sensor 50 for detecting a magnetic field is in the present embodiment, within the cell housing 3 , about equidistant from the terminals 11 . 12 spaced, attached. The sensor 50 is oriented in such a way that the sensor 50 can detect a magnetic field generated by a current flowing in parallel to the winding axis A. In particular, the sensor detects 50 no magnetic field generated by a current flowing tangentially to the winding axis A around the Wickachse A.

At the in 2 . 3 . 4 and 5 shown electrode units 10 the strip-shaped anode segments run 71 . 72 , the strip-shaped cathode segments 81 . 82 , the strip-shaped Anodenableitersegmente 76 . 77 and the strip-shaped Kathodenableitersegmente 86 . 87 each tangent to the winding axis A. It is also conceivable that the strip-shaped anode segments 71 . 72 , the strip-shaped cathode segments 81 . 82 , the strip-shaped Anodenableitersegmente 76 . 77 and the strip-shaped Kathodenableitersegmente 86 . 87 run parallel to the winding axis A.

In this case, a compensating current Ia caused by a defect would flow in a direction tangential to the winding axis A and generate a corresponding magnetic field. To detect such a compensation current Ia would then be a sensor 50 provided, which is oriented such that the sensor 50 can detect a magnetic field generated by a current flowing tangentially to the winding axis A.

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

• DE 102013200714 A1 [0010]
• US 2013/0113495 A1 [0011]
• US 2011/0110183169 A1 [0012]

Claims (10)

Electrode unit ( 10 ) for a battery cell ( 2 ) comprising an anode ( 21 ) containing an anodic active material ( 41 ) and an anodic current collector ( 31 ), and a cathode ( 22 ) containing a cathodic active material ( 42 ) and a cathodic current collector ( 32 ), and a separator ( 18 ), which the anode ( 21 ) from the cathode ( 22 ), characterized in that the anodic active material ( 41 ) in the form of strip-shaped anode segments ( 71 . 72 ), and / or that the cathodic active material ( 42 ) in the form of strip-shaped cathode segments ( 81 . 82 ), the separator ( 18 ) is formed continuously. Electrode unit ( 10 ) according to claim 1, characterized in that the anodic current collector ( 31 ) is formed continuously, and / or that the cathodic current collector ( 32 ) is formed continuously. Electrode unit ( 10 ) according to claim 1, characterized in that the anodic current collector ( 31 ) in the form of strip-shaped anode drain segments ( 76 . 77 ), and / or that the cathodic current collector ( 32 ) in the form of strip-shaped cathode drainage segments ( 86 . 87 ) is present. Electrode unit ( 10 ) according to claim 3, characterized in that the anode drain segments ( 76 . 77 ) by connecting webs ( 90 ), and / or that the cathode drain segments ( 86 . 87 ) by connecting webs ( 90 ) are interconnected. Battery cell ( 2 ) comprising at least one electrode unit ( 10 ) according to any one of the preceding claims. Method for operating a battery cell ( 2 ) according to claim 5, characterized in that one of an anode segment ( 71 . 72 ) to a neighboring anode segment ( 71 . 72 ) flowing compensating current (Ia) is detected, and / or that one of a cathode segment ( 81 . 82 ) to a neighboring cathode segment ( 81 . 82 ) flowing compensating current (Ia) is detected. A method according to claim 6, characterized in that a magnetic field is generated, which is generated by the compensating current (Ia), which by a continuously formed anodic current collector ( 31 ) and / or by a continuously formed cathodic current collector ( 32 ) flows. A method according to claim 6, characterized in that a magnetic field is measured, which is generated by the compensating current (Ia), which by a connecting web ( 90 ) through which anode drain segments ( 76 . 77 ), and / or through which cathode drain segments ( 86 . 87 ) are interconnected. A method according to claim 6, characterized in that one at a connecting web ( 90 ) through which anode drain segments ( 76 . 77 ), and / or through which cathode drain segments ( 86 . 87 ) are measured, voltage applied, which is generated by the compensating current (Ia) passing through the connecting web ( 90 ) flows. Use of the battery cell ( 2 ) according to claim 5 in a stationary energy storage, in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product.

Images