Energy store having a separating-element protector

Abstract

The invention relates to an electrical energy store which comprises a housing. The energy store also comprises a first storage cell and a second storage cell which are arranged one next to the other in the housing such that an intermediate space is formed between the first storage cell and the second storage cell, which space is filled with a filling compound. Furthermore, the energy store comprises a cell contacting system which electrically conductively connects a contact point of the first storage cell to a contact point of the second storage cell via a connecting line. In addition, the energy store comprises a separating element which is designed to interrupt the connecting line when thermal energy acts on the separating element, and a separating-element protector which surrounds the separating element, wherein the separating-element protector comprises a protective material which has a higher melting temperature than the filling compound.

Description

[0001] Energy storage with a separator protection

[0002] The invention relates to an electrical energy storage device with a plurality of storage cells.

[0003] An at least partially electrically powered vehicle has an energy storage device for storing electrical energy for operating an electric drive motor of the vehicle. The energy storage device typically has a plurality of storage cells, in particular a plurality of round cells, arranged in a housing of the energy storage device. The energy storage device further has a cell contacting system designed to electrically connect the individual storage cells to one another according to a specific electrical circuit (e.g., a 3P, 4P, or 5P circuit).

[0004] During operation of the energy storage device, a thermal event can occur, resulting in a short circuit in a storage cell. This document addresses the technical problem of providing efficient and reliable protection for the storage cells of an electrical energy storage device in the event of a thermal event in a storage cell of the energy storage device. This problem is solved by the independent claim. Advantageous embodiments are described, among others, in the dependent claims.It should be noted that additional features of a claim dependent on an independent claim may constitute a separate invention, independent of the combination of all features of the independent claim, without the features of the independent claim or only in combination with a subset of the features of the independent claim. This invention may be made the subject of an independent claim, a divisional application, or a subsequent application. This also applies to technical teachings described in the description, which may constitute an invention independent of the features of the independent claims.

[0005] According to one aspect, an electrical energy storage device is described. The energy storage device can be designed to store electrical energy for operating an electric drive motor of a motor vehicle. The energy storage device can, for example, have a nominal voltage of 100V or more, in particular of 300V or more.

[0006] The energy storage device comprises a housing. Furthermore, the energy storage device comprises a first storage cell and a second storage cell, which are arranged side by side in the housing, such that a gap is formed between the first storage cell and the second storage cell. The gap between the storage cells can be filled with a filling compound. The filling compound can comprise polyurethane, in particular a polyurethane foam.

[0007] Typically, the energy storage device comprises Z storage cells, with Z>10, in particular Z>100, arranged side by side in the housing. The spaces between directly adjacent storage cells can each be filled, in particular filled, with the filling compound.

[0008] The first memory cell and the second memory cell (in particular the Z memory cells) can each be formed as a round cell with a sidewall, wherein the sidewall extends from a first end face to an opposite second end face. The gap can be arranged between the sidewalls of the first memory cell and the second memory cell (generally between the sidewalls of directly adjacent memory cells).

[0009] The energy storage device further comprises a cell contacting system which electrically connects an (electrical) contact point (e.g. a positive pole or a negative pole) of the first storage cell via a connecting line to an (electrical) contact point (e.g. a negative pole or a positive pole) of the second storage cell (and in doing so, for example, electrically connects them in series). The cell contacting system can in particular be designed to electrically connect Z / M subgroups, each with M storage cells, in series via connecting lines, e.g. with M>1 and / or M<10. The cell contacting system can be arranged on the first end face of the first storage cell and the second storage cell (in particular of the Z storage cells).

[0010] Furthermore, the energy storage device comprises at least one isolating element which is designed to interrupt the connecting line when thermal energy acts on the isolating element. The isolating element can comprise a fuse. In particular, the isolating element can be a fuse. The connecting line between two storage cells can be designed, for example, as a metal sheet. The isolating element can be formed by a local thinning of the metal sheet. The energy storage device can have a isolating element between each two directly successive subgroups of storage cells. In particular, a isolating element can be designed such that the isolating element disconnects the connecting line when the temperature in the immediate vicinity is equal to or greater than a specific temperature threshold value (e.g. between 300°C and 700°C) for at least a specific triggering period (e.g. 100 ms or more and / or 1 second or less).The thermal energy for triggering the separating element can be caused by a thermal event in the first or second storage cell.

[0011] The energy storage device further comprises a separator guard that encloses the separator. The individual separators of the energy storage device can each be enclosed by a separator guard.

[0012] The separating element protection for a separating element comprises a protective material. The protective material can enclose the (metallic) separating element with a layer thickness of 1 mm or more, in particular 2 mm or more, in particular 5 mm or more.

[0013] The protective material is preferably a thermally stable material. The protective material preferably has a higher melting temperature than the filling material. The melting temperature of the protective material can be, for example, 10% or more, in particular 20% or more, in particular 50% or more, higher than the melting temperature of the filling material. The protective material can comprise, for example, aerogel and / or glass and / or a foam material.

[0014] The protective material is preferably designed such that the protective material essentially does not change into the liquid and / or gaseous state when a thermal event occurs in the first storage cell. On the other hand, the filler material is typically designed such that the filler material changes into the liquid and / or gaseous state when a thermal event occurs in the first storage cell. Alternatively or additionally, the protective material can be designed such that the protective material essentially has the same thermally insulating effect when a thermal event occurs in the first storage cell, in particular at a temperature of 500°C or more, as in the normal state of the energy storage device without the presence of a thermal event, in particular at a temperature of 100°C or less. The separating element protection can thus have a thermally insulating effect.The thermal conductivity, density and / or heat capacity of the protective material can be such that the insulating effect is maintained over the entire relevant temperature range (e.g. between 0°C and 1000°C).

[0015] An energy storage device is thus described in which the one or more isolating elements, by means of which the propagation of an electrical short circuit from an impaired storage cell to one of the several further storage cells of the energy storage device can be prevented, are each surrounded by a spatially limited isolating element protection.

[0016] By providing isolating element protection for an isolating element, the protective material in the immediate vicinity of the isolating element can maintain its current (fixed) phase state even in the event of a thermal event in a storage cell. As a result, no thermal energy is drawn from the immediate vicinity of the isolating element, which could prevent the isolating element from triggering. By providing isolating element protection for the one or more isolating elements of the energy storage device, particularly reliable short-circuit protection can be provided.

[0017] The separator protection element can (in addition to the respective separator itself) enclose the contact point of the first memory cell and / or the second memory cell. This can further improve short-circuit protection.

[0018] The filler compound can be directly adjacent to the separating element protection of one or more separating elements. The separating element protection can be designed to spatially space the respective separating element from the filler compound, in particular such that the filler compound is at a distance of at least 2 mm, preferably at least 5 mm, from the respective separating element. This allows for particularly reliable short-circuit protection.

[0019] According to a further aspect, a (road) motor vehicle (in particular a passenger car, a truck, a bus, or a motorcycle) is described, which comprises the energy storage device described in this document. The vehicle may comprise an electric drive motor configured to drive the vehicle. The energy storage device may be configured to store electrical energy for operating the drive motor.

[0020] It should be noted that the devices and systems described in this document can be used both alone and in combination with other devices and systems described in this document. Furthermore, any aspects of the devices and systems described in this document can be combined in a variety of ways. In particular, the features of the claims can be combined in a variety of ways. Furthermore, features listed in parentheses are to be understood as optional features.

[0021] The invention will be described in more detail below using exemplary embodiments.

[0022] Figure 1 shows an exemplary vehicle with an energy storage device for storing electrical energy;

[0023] Figure 2a shows an exemplary round cell; Figure 2b shows an exemplary electrical energy storage device with several storage cells; and

[0024] Figure 3 shows an exemplary energy storage device with a separating element protection.

[0025] As stated at the outset, this document addresses the issue of efficiently and reliably protecting one or more neighboring storage cells of an electrical energy storage device from the effects of a thermal event in a specific storage cell of an electrical energy storage device. In this context, Fig. 1 shows an exemplary vehicle 100 with an electrical energy storage device 110 for storing electrical energy and with an electric drive motor 102 powered by electrical energy from the energy storage device 110.

[0026] The energy storage device 110 comprises a plurality of storage cells, in particular round cells. Fig. 2a shows an exemplary storage cell 200, in particular a round cell, for an electrical energy storage device 110. The storage cell 200 has a circular-cylindrical shape. A positive contact point 201 and a negative contact point 202 for electrically connecting the storage cell 200 are arranged on an end face of the storage cell 200. The positive contact point 201 can be formed by the end face of the cylindrical storage cell 200. The end face of the storage cell 200 can be arranged on the end side of a (circular-cylindrical) housing side wall 206 of the storage cell 200. The negative contact point 202 can be formed by a bolt that protrudes from the end face of the storage cell 200. In another example, the polarity of the contact points 201, 202 can be exactly reversed.

[0027] Fig. 2b shows a section of an exemplary energy storage device 110 with two storage cells 200, 230, wherein the storage cells 200, 230 are typically structurally identical. The storage cells 200, 230 are arranged side by side (i.e., lateral surface 206 to lateral surface 206), in particular such that the contact points 201, 202 of the individual storage cells 200 are arranged on a uniform side (in Fig. 2b, on the top side). The energy storage device 110 can, for example, have Z=100 or more storage cells 200, or Z=1000 or more storage cells 200, 230.

[0028] The individual storage cells 200, 230 can be electrically connected to one another via a cell contacting system 220. The cell contacting system 220 can, for example, have a frame with connecting lines or with connecting webs for electrically contacting the contact points 201, 202 of the individual storage cells 200, 230. The cell contacting system 220 can be arranged on the (contact) side of the storage cells 200, 230 on which the contact points 201, 202 of the storage cells 200, 230 are also arranged. A (second) housing wall 212 of the housing of the energy storage device 110 can be arranged on the opposite side of the storage cells 200, 230. The opposite (second) housing wall 212 can, for example, be designed as a cooling plate for cooling the individual storage cells 200, 230. An underfloor protection 213 can be arranged between the (second) housing wall 212 and the (underlying) end face of the individual storage cells 200, 230.

[0029] The energy storage device 110 may further comprise a (first) housing wall 211 that covers the cell contact system 220 (and is arranged on the opposite side of the energy storage device 110 relative to the second housing wall 212). The cavities between the individual components of the energy storage device 110, in particular the cavities between the individual storage cells 200, 230, may be filled with a filling compound 214.

[0030] As shown in Fig. 2b, the (circular-cylindrical) storage cells 200, 230 can be arranged such that the lateral surfaces (i.e., the side walls 206) of directly adjacent storage cells 200, 230 touch one another. The storage cells 200 can be arranged next to one another in a honeycomb pattern, in particular such that a cavity is enclosed by a subgroup of three storage cells 200, 230 in each case, and / or such that six storage cells 200, 230 in each case enclose exactly one further storage cell 200, 230. In this way, the (circular-cylindrical) storage cells 200 can be arranged in a particularly dense manner. The circular-cylindrical storage cells 200, 230 can in particular be arranged in the arrangement with the highest possible packing density.

[0031] The storage cells 200, 230 can be interconnected in a specific electrical arrangement by the cell contacting system 220. The energy storage device 110 can, for example, have Z storage cells 200, 230, which are divided into subgroups of M storage cells 200, 230 each. The M storage cells 200, 230 of a subgroup can be arranged electrically parallel to one another by the cell contacting system 220. The energy storage device 110 then has a so-called MP (e.g., 3P for M=3, 4P for M=4, or 5P for M=5) arrangement.

[0032] The two memory cells 200, 230 shown in Fig. 2b are electrically connected in series via the cell contact system 220. The connecting line shown in Fig. 2b connects the second contact point 202 of the first memory cell 200 to the first contact point 201 of the second memory cell 230. A separating element 221, e.g., a fuse, can be arranged on the connecting line and is designed to separate the electrically conductive connection between the first memory cell 200 and the second memory cell 230 when a relatively high temperature is present.

[0033] It may happen that a storage cell 200 of the energy storage device 110, e.g., the first storage cell 200, experiences a thermal event 210, as a result of which a relatively large amount of thermal energy is released at the first storage cell 200, in particular at the contact points 201, 202 of the first storage cell 200. The cause or consequence of the thermal event 210 of the first storage cell 200 may be an electrical short circuit in the first storage cell 200. The isolating element 221 of the cell contacting system 220 is triggered by the thermal energy released due to the thermal event 210, as a result of which the electrically conductive connection to the one or more adjacent storage cells 230, in particular to the second storage cell 230, is severed.As a result, impairment of the one or more other storage cells 230 of the energy storage device 110 due to the electrical short circuit in the first storage cell 200 can be reliably avoided.

[0034] The amount of thermal energy released during the thermal event 210 can cause the filler mass 214 in the vicinity of the first storage cell 200 to transition from the solid state to the liquid and / or gaseous state. This phase transition can lead to the absorption of a relatively high amount of thermal energy by the filler mass 214, which in turn can result in the remaining amount of thermal energy no longer reliably triggering the isolating element 221, thus preventing reliable short-circuit separation of one or more other storage cells 230 from the first storage cell 200. In particular, the phase transition of the filler mass 214 directly adjacent to the isolating element 221 can lead to a locally limited cooling effect, by which the isolating element 221 is cooled (relative to the environment) and, as a result, is not triggered.

[0035] The energy storage device 110 can, as shown by way of example in Fig. 3, have a separating element protection 300 that surrounds the separating element 221 arranged between the first storage cell 200 and the second storage cell 230. Alternatively or additionally, a separating element protection 300 can be arranged at the one or more contact points 201, 202 of the individual storage cells 200, 230. The separating element protection 300 can be provided by a thermally stable material, e.g., by an aerogel or glass, wherein the protective material of the separating element protection 300 remains stable in the presence of a thermal event 210 and the thermal event 210 does not cause a phase transition of the protective material (into the liquid and / or gaseous state).

[0036] In the example shown in Fig. 3, the separating element protection 300 is achieved by using a different protective material instead of the filling compound 214 (e.g., instead of polyurethane (PU) foam) in a partial area of ​​the energy storage device 110. The partial area with the protective material can comprise the separating element 221 and / or one or both contact points 201, 202 of the first storage cell 200. The protective material preferably has a higher melting temperature than the filling compound 214.

[0037] The separating element protection 300 can thus be achieved by completely or partially enclosing a portion of the energy storage device 110 with a thermally stable protective material (for example, aerogel, glass, etc.). The aforementioned cooling effects can be reduced or completely suppressed, in particular, by encapsulating one or more contact points 201, 202 (i.e., terminals) of the first storage cell 200 and / or the separating element 221.

[0038] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and figures are intended only to illustrate the principle of the proposed devices and systems by way of example.

Claims

Claims 1) Electrical energy storage device (110) comprising - a housing (211, 212); - a first storage cell (200) and a second storage cell (230) arranged side by side in the housing (211, 212) such that an intermediate space is formed between the first storage cell (200) and the second storage cell (230), which intermediate space is filled with a filling compound (214); - a cell contacting system (220) which electrically connects a contact point (202) of the first memory cell (200) to a contact point (201) of the second memory cell (230) via a connecting line; - a separating element (221) which is designed to interrupt the connecting line when thermal energy is applied to the separating element (221); and - a separating element protector (300) enclosing the separating element (221); wherein the separating element protector (300) comprises a protective material having a higher melting temperature than the filling compound (214). 2) Energy storage device (110) according to claim 1, wherein - the protective material is designed such that the protective material does not substantially change into the liquid and / or gaseous state in the presence of a thermal event (210) of the first storage cell (200); and / or - the filling mass (214) is designed such that the filling mass (214) changes into the liquid and / or gaseous state when a thermal event (210) of the first storage cell (200) occurs. 3) Energy storage device (110) according to one of the preceding claims, wherein the protective material is designed such that the protective material has substantially the same thermally insulating effect in the presence of a thermal event (210) of the first storage cell (200), in particular at a temperature of 500°C or more, as in a normal state of the energy storage device (110) without the presence of a thermal event (210), in particular at a temperature of 100°C or less. 4) Energy storage device (110) according to one of the preceding claims, wherein the protective material comprises aerogel and / or glass and / or a foam material. 5) Energy storage device (110) according to one of the preceding claims, wherein the filling compound (214) comprises polyurethane, in particular a polyurethane foam. 6) Energy storage device (110) according to one of the preceding claims, wherein the separating element protection (300) encloses the contact point (201, 202) of the first storage cell (200) and / or the second storage cell (230). 7) Energy storage device (110) according to one of the preceding claims, wherein the filling compound (214) directly adjoins the separating element protection (300). 8) Energy storage device (110) according to one of the preceding claims, wherein the separating element protection (300) is designed to spatially space the separating element (300) from the filling compound (214), in particular such that the filling compound (214) has a distance of at least 2 mm, preferably of at least 5 mm, from the separating element (300). 9) Energy storage device (110) according to one of the preceding claims, wherein - the first storage cell (200) and the second storage cell (230) are each designed as a round cell with a side wall (206) which extends from a first end face to an opposite second end face; - the gap is arranged between the side walls (206) of the first memory cell (200) and the second memory cell (230); and - the cell contacting system (220) is arranged on the first end face of the first storage cell (200) and the second storage cell (230). 10) Energy storage device (110) according to one of the preceding claims, wherein - the energy storage device (110) comprises Z storage cells (200, 230), with Z>10, in particular Z>100, which are arranged next to one another in the housing (211, 212); - the cell contacting system (220) is designed to electrically connect Z / M subgroups each having M storage cells (200, 230) in series by connecting lines, with M>1 and / or M<10; - the energy storage device (110) comprises a separating element (221) between each of two directly successive subgroups of storage cells (200, 230); and - the individual separating elements (221) are each enclosed by a separating element protection (300). 11) Vehicle (100) comprising, - an electric drive motor configured to drive the vehicle (100); and - an electrical energy storage device (110) according to one of the preceding claims, wherein the energy storage device (110) is designed to store electrical energy for the operation of the drive motor.

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