Energy storage system

Abstract

An energy storage system (1), comprising a housing (2), in which multiple energy storage cells (3) are located, wherein: frame elements (5) are located between the energy storage cells (3) and separate the energy storage cells (3) from each other; sealing elements (7) are associated with the peripheral edges (6) of the frame elements (5); and the sealing elements (7) form at least part of a non-return valve.

Description

[0001] Applicant: Carl Freudenberg KG, 69469 Weinheim

[0002] Energy storage system

[0003] The invention relates to an energy storage system comprising a housing in which a plurality of energy storage cells are arranged, wherein frame elements are arranged between the energy storage cells, which frame elements separate the energy storage cells, wherein sealing bodies are assigned to the surrounding edges of the frame elements.

[0004] Such an energy storage system is known from EP 2 273 162 A1. Energy storage systems containing energy storage cells are widespread and are used in particular as rechargeable storage devices for electrical energy in mobile and stationary systems. Energy storage systems in the form of rechargeable storage devices are used in portable electronic devices, for example, in measuring devices, medical devices, tools, and consumer goods. Furthermore, energy storage systems in the form of rechargeable storage devices are used to provide electrical energy for electrically powered means of transport. Electrically powered means of transport can be two-wheelers, four-wheelers, for example, passenger cars, or commercial vehicles such as buses, trucks, rail vehicles, or forklifts. Furthermore, energy storage systems are also used in ships and aircraft.

[0005] It is also known to provide energy storage systems in the form of rechargeable storage devices in stationary applications, for example, as backup systems in network systems and for storing electrical energy from renewable energy sources. A frequently used energy storage system is a rechargeable storage device in the form of a lithium-ion battery. Such energy storage systems, like other rechargeable storage devices, usually have several storage cells arranged in a housing. Several energy storage cells arranged in a housing and electrically connected to one another form a module.

[0006] Other well-known energy storage systems include lithium-sulfur batteries, solid-state batteries, and metal-air batteries.

[0007] The aforementioned rechargeable storage devices exhibit maximum electrical capacity only within a limited temperature range. If this temperature range is exceeded, the electrical capacity of the energy storage device drops significantly, or at the very least, its functionality is impaired.

[0008] Excessively high temperatures, in particular, can lead to damage to the energy storage device. In this context, the so-called "thermal runaway" is particularly common in lithium-ion batteries. This process releases large amounts of thermal energy and gaseous decomposition products in a short period of time, leading to high pressure and high temperatures within the storage cells. This effect is particularly problematic in storage devices with high energy density and many energy storage cells in a small space. This is the case, for example, in energy storage systems for providing electrical energy for electric vehicles.

[0009] During thermal runaway of an energy storage cell, temperatures in the range of 600°C or more can occur within a period of a few seconds. Suitable measures should be taken to reduce the energy transfer to neighboring storage cells to such an extent that the temperature of the neighboring energy storage cells does not rise excessively. The temperature of the neighboring storage cells should preferably not exceed 100°C. However, this value strongly depends on the chemicals used for the energy storage cells. Irreversible damage to the affected energy storage cell cannot be prevented, but it can be prevented that the damage spreads to neighboring energy storage cells (thermal propagation).

[0010] In addition to thermal runaway, venting is another type of damage to an energy storage cell. For example, in pouch-type energy storage cells, gases formed within the energy storage cell are released through an opening in the foil casing. This type of venting can occur particularly during thermal runaway. In the case of a defective venting, temperatures are usually either moderately elevated or not at all. The released gases are usually degradation products of the materials present inside the energy storage cell, such as the electrolyte or binding agents. The released gases are highly reactive and can damage neighboring storage cells. Therefore, such an event is critical for the safety of an energy storage system.

[0011] The invention is based on the object of providing an energy storage system with improved operational reliability.

[0012] This object is achieved by the features of claim 1. The subclaims refer to advantageous embodiments.

[0013] The energy storage system according to the invention comprises a housing in which a plurality of energy storage cells are arranged, wherein frame elements which separate the energy storage cells are arranged between the energy storage cells, wherein sealing bodies are assigned to the surrounding edges of the frame elements, wherein the sealing bodies form a check valve at least in sections.

[0014] Accordingly, the energy storage cells in the inventive

[0015] Energy storage system separated and separated from one another by frame elements. Depending on the design of the energy storage cells, the frame elements can be plate-shaped. The frame elements cover the main sides of the energy storage cells. Sealing bodies are arranged in the edge areas, with the sealing bodies being attached to the frame elements. The energy storage cells are individually encapsulated by the frame elements and the sealing bodies attached to the frame elements. Because a check valve is formed in at least some sections of the sealing bodies, pressure equalization can occur in the event of a malfunction. If gas products are released from an individual energy storage cell due to an accident, excess pressure builds up in the space between the frame elements and the surrounding sealing body, which can be released via the check valve.The check valve can open into a chamber or channel through which the degradation products can be discharged. Only the check valve associated with the damaged energy storage cell opens. The check valves associated with the neighboring energy storage cells remain closed, preventing the harmful products escaping from the damaged energy storage cell from coming into contact with the other energy storage cells. This can prevent the incident from spreading to neighboring energy storage cells.

[0016] The energy storage cells can each be arranged between frame elements, with sealing lips formed from the sealing bodies, with the sealing lips of adjacent frame elements facing each other. In this configuration, the sealing lips abut one another in a linear fashion, and the contacting portions of the sealing lips can form the check valves. This allows harmful gases to escape from the edge areas of the energy storage cells at any location.

[0017] The sealing lips can be elastically pre-stressed to seal. This ensures that no unwanted products from outside can penetrate into the space between the frame elements and the sealing bodies, in which the energy storage cells are arranged. The sealing lips can be curved in the opposite direction to the energy storage cells. In this design, the sealing lips protrude outwards. If the sealing lips are also pre-stressed against each other, an opening similar to a check valve is formed. If the pressure inside - i.e. in the space in which the energy storage cells are arranged - increases, the sealing lips are pushed outwards, eventually lifting away from each other and opening a passage. An increase in pressure on the outside causes the sealing lips to press more tightly against each other, blocking the passage.

[0018] The sealing bodies can be made of an elastic material. For this purpose, the sealing bodies can be made of an elastomeric sealing material, such as silicone rubber. In this design, the sealing lips of the sealing bodies are elastically movable, allowing the sealing lips to form a particularly effective non-return function.

[0019] The sealing bodies can be made of dimensionally stable material. For this purpose, it is conceivable to form the sealing bodies in the form of sealing lips from a strip-like material, with the strip-like material forming sealing lips that bulge outward after assembly. In this design, the sealing lips function as flaps and also allow harmful gases to escape from the inside to the outside. For this purpose, the sealing bodies are preferably pivotably mounted on the frame elements.

[0020] The energy storage cells can be designed as pouch cells and have a circumferential sealing seam. In pouch cells, the active material is arranged in a foil, with the foil forming a circumferential sealing seam. This is particularly the case with two-part foils, between which the active material is arranged.

[0021] The sealing lips can be elastically pre-tensioned to engage the sealing seam. In this design, the sealing elements function not only as a sealing element but also as a retaining element. The energy storage cells are secured between the frame elements by the sealing seams clamped between the sealing lips. This eliminates the need for additional retaining elements. In this design, the interior is sealed between the sealing lip and the sealing seam. Sealing lips of the sealing elements are thus located on both sides of the circumferential sealing seam of an energy storage cell.

[0022] The sealing elements can be held in place by a form-fitting manner on the frame elements. This simplifies the assembly and manufacturability of the energy storage system.

[0023] Some embodiments of the energy storage system according to the invention are explained in more detail below with reference to the figures. The figures show, schematically:

[0024] Fig. 1 shows an energy storage system with flap-shaped sealing bodies in section; Fig. 2 shows an energy storage system with elastic sealing bodies in section.

[0025] The figures show an energy storage system 1, comprising a housing 2 in which a plurality of energy storage cells 3 are arranged. The energy storage cells 3 each have a film housing which is formed from a first film and a second film, wherein the first film and the second film are materially connected to one another along a circumferential edge by means of a sealing seam 4. The film housing accommodates an electrode-separator arrangement, wherein electrodes protrude from the film housing in the region of the sealing seam 4. The electrodes can be electrically contacted via the electrodes. The first film and the second film are made of aluminum and provided on the inside with a coating based on a polyolefinic, non-conductive adhesion promoter and on the outside with a plastic coating based on a polyamide.The energy storage cells 3 are designed as lithium-ion accumulators. The energy storage cells 3 are separated from one another by frame elements 5. The energy storage cells 3 and frame elements 5 form a sandwich-like structure. Sealing bodies 7 are assigned to the surrounding edges 6 of the frame elements 5. The sealing bodies 7 form a check valve, at least in sections.

[0026] The energy storage cells 3 are each arranged between two frame elements 5, with sealing lips 8 being formed from the sealing bodies 7, with the sealing lips 8 of adjacent frame elements 5 facing each other. The sealing lips 8 are curved toward the energy storage cells 3. The sealing lips 8 open into a region of the housing 2 that forms a discharge area.

[0027] The sealing lips 8 rest with prestress against the sealing seams 4 of the energy storage cells 3. If, in the event of damage, harmful gases are released from an energy storage cell 3, an overpressure builds up in the space between the frame elements 5 and the sealing bodies 7, which causes the sealing lips 8 to move away from the sealing seam 4, allowing harmful gases to enter the discharge area. In the remaining undamaged energy storage cells 3, however, the sealing bodies 7 rest tightly against the sealing seams 4, preventing the harmful gases escaping from the damaged energy storage cell 3 from coming into contact with the other energy storage cells 3.

[0028] Figure 1 shows an embodiment in which the sealing bodies 7 are made of dimensionally stable material. The sealing bodies 7 are strip-shaped, with the strip-shaped elements forming sealing lips 8. The sealing bodies 7 are pivotably mounted on the frame elements 5.

[0029] Figure 2 shows an embodiment in which the sealing bodies 7 are made of elastic material. In the present embodiment, the sealing bodies 7 are made of elastomeric material and are formed of silicone rubber. The sealing bodies 7 are held in a form-fitting manner on the frame elements 5. Due to the elastic design of the sealing bodies 7, the sealing lips 8 rest against the sealing seams 4 of the energy storage cells 3 with elastic prestress.

Claims

Patent claims 1. Energy storage system (1), comprising a housing (2) in which a plurality of energy storage cells (3) are arranged, wherein frame elements (5) are arranged between the energy storage cells (3), which frame elements separate the energy storage cells (3), wherein sealing bodies (7) are assigned to the surrounding edges (6) of the frame elements (5), characterized in that the sealing bodies (7) form a check valve at least in sections.

2. Energy storage system according to claim 1, characterized in that the energy storage cells (3) are each arranged between frame elements (5), wherein sealing lips (8) are formed from the sealing bodies (7), wherein the sealing lips (8) of adjacent frame elements (5) face one another.

3. Energy storage system according to claim 2, characterized in that the sealing lips (8) seal with elastic prestress.

4. Energy storage system according to claim 2 or 3, characterized in that the sealing lips (8) are curved towards the energy storage cells (3).

5. Energy storage system according to one of claims 1 to 4, characterized in that the sealing bodies (7) are made of elastic material.

6. Energy storage system according to one of claims 1 to 4, characterized in that the sealing bodies (7) are made of dimensionally stable material.

7. Energy storage system according to one of claims 1 to 6, characterized in that the sealing bodies (7) are pivotably fixed to the frame elements (5).

8. Energy storage system according to one of claims 1 to 7, characterized in that the energy storage cells (3) are designed as pouch cells and have a circumferential sealing seam 4.

9. Energy storage system according to claim 8, characterized in that the Sealing lips (8) with elastic pre-tension come into contact with the sealing seams 4.

10. Energy storage system according to one of claims 1 to 9, characterized in that the sealing bodies (7) are held in a form-fitting manner on the frame elements (5).

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