Battery housing cover with a section comprising a fibre composite with an oxide matrix
Patent Information
- Application Number
- EP2024705482
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-02-15
- Filing Date
- 2024-02-15
- Publication Date
- 2025-12-24
AI Technical Summary
Lithium-ion battery cells in electric vehicles can generate intense heat during a fire, leading to potentially life-threatening penetration of flames and smoke gases into the passenger compartment due to uncontrolled gas release through pressure relief valves or rupture disks, necessitating enhanced fire protection measures.
A battery housing cover with locally reinforced sections made of fiber composite materials featuring an oxidic matrix, specifically oxide ceramic composite materials, is designed to be strategically positioned opposite outlet points to manage and dissipate the hot gas stream effectively, enhancing chemical, mechanical, and temperature resistance while being cost-effective.
The solution effectively contains the high-temperature gas stream, limiting external temperatures to 200°C and providing sufficient protection for vehicle occupants by preventing flame and smoke penetration, thus meeting regulatory requirements for occupant safety during a battery cell fire.
Smart Images
Figure EP2024053875_22082024_PF_FP
Abstract
Description
[0001] Battery housing cover with a section comprising a fiber composite with an oxide matrix
[0002] The invention relates to a battery housing cover according to claim 1. Furthermore, the invention relates to a method for producing a battery housing cover according to claim 5, a battery cell arrangement according to claim 6, a method for producing an arrangement according to claim 11 and an electric vehicle according to claim 12 and the use of a section comprising a fiber composite with an oxide matrix according to claim 13.
[0003] With the increasing popularity of electric cars, the issue of fire protection is becoming more and more important. This is because lithium-ion battery cells used to power vehicles can generate particularly strong heat in the event of a fire. In the event of thermal runaway of a battery cell, any excess pressure built up in the battery cell is usually released in a defined manner via a designated outlet point, such as a pressure relief valve or rupture disc. This means that if there is excess pressure in the housing, a directed, hot, supersonic gas stream, sometimes containing metallic particles and / or soot, is released into the environment via the outlet point. The gas stream escapes through the outlet point in a directed jet that spreads out in a cone shape. The temperature of the gas can exceed 1200 °C.The hot gases and the particles present in the gas can perforate the battery housing cover and cause life-threatening flames and smoke to penetrate the vehicle's passenger compartment, as battery systems are often located beneath the passenger compartment. Furthermore, if one battery cell catches fire, neighboring battery cells often also catch fire.
[0004] There are regulations (for example, GTR20; Global Technical Regulation on Electric Vehicle Safety - EVS) that stipulate that in the event of a fire involving at least one battery cell, the occupants in the passenger compartment are protected for at least five minutes. Accordingly, the penetration of flames and smoke gases must be prevented for this time. The underlying object of the invention is therefore to provide a battery housing cover, a method for producing a battery housing cover, an assembly, a method for producing the assembly, and an electric vehicle, all of which are suitable for enabling particularly good protection for the occupants of a vehicle.
[0005] The object is achieved according to the invention with the features of the independent claims. Further advantages and practical embodiments are explained in connection with the dependent claims.
[0006] A battery housing cover according to the invention serves to cover at least one battery cell, in particular a lithium-ion battery cell. The battery housing cover can be part of a multi-part battery housing, wherein at least one battery cell can be accommodated in the battery housing. The battery housing cover can in particular be designed as a plate or as a base pan. This is in particular a battery housing cover for arrangement in an electric vehicle, wherein one or more battery cells for supplying power to an electric vehicle are covered by the battery housing cover. In the vehicle, the battery housing cover can be arranged above the at least one battery cell, viewed in the vertical direction of the vehicle, or else arranged below the at least one battery cell.
[0007] The battery housing cover has a base body, whereby the base body can be made of metal, such as alloyed steel or aluminum, or of glass fiber reinforced plastic (GRP) or carbon fiber reinforced plastic (CFRP).
[0008] At least one section comprising a fiber composite with an oxide matrix is arranged on the base body, and in particular a section comprising an oxide-ceramic composite material. A section here means that the base body is partially or sectionally, i.e. only locally, provided with the fiber composite with an oxide matrix. As explained below in connection with the arrangement, the section is arranged on the battery housing cover such that it is arranged in an outlet direction of an outlet point of a battery cell and lies opposite this. The outlet point is in particular a pressure relief valve or a bursting disc, whereby in the event of excess pressure in the battery cell, for example due to a fire in the battery cell, a gas flow can escape from the housing of the battery cell in as directed and controlled a manner as possible in order to relieve the load on the housing of the battery cell and dissipate heat.This means that in this case, where such a directed hot gas stream escapes from the battery cells at specific points, the battery housing cover is subjected to particular stresses in certain areas. By locally reinforcing the base body with sections of fiber composite with an oxide matrix, the base body can be made more chemically and mechanically resistant, as well as more temperature-resistant. At the same time, purely local reinforcement is particularly cost-effective compared to completely lining or manufacturing the battery housing cover from fiber composite with an oxide matrix.
[0009] The fiber composite with an oxide matrix is, in particular, an oxide-ceramic composite material, which is also commonly referred to as an oxide ceramic matrix composite (OCMC). Such an oxide-ceramic composite material comprises, in particular, a plurality of fibers. In particular, the fibers are oxide-ceramic multifilament fibers. Alternatively, they can also be silicate fibers, in particular glass fibers, carbon or mineral fibers. In the context of the present invention, silicate fibers are understood to mean fibers that consist predominantly of SiO2. The SiO2 content is, in particular, at least 90% and preferably at least 94%. The SiC content can be up to 99.95 wt.%. In addition to SiC, glass fibers contain a certain proportion of Al2O3 and can also contain other components such as MgO, B2O3 or CaO.The glass fibers can in particular also be so-called E-glass fibers, comprising or consisting of aluminum borosilicate glass. Glass fibers in particular have the advantage of being particularly cost-effective while having similar properties. The fibers are embedded in a matrix (also called slurry). Oxide-ceramic multifilament fibers can be oxide-ceramic continuous fibers and / or oxide-ceramic short fibers. Likewise, silicate fibers can be continuous fibers or short fibers. Continuous fibers have a length in the range of many tens of centimeters to many meters. Short fibers have a length in the range of a few millimeters to a few centimeters. A fiber referred to here is in particular a fiber bundle (roving) which comprises a large number of individual fibers. The matrix can also be an oxide-ceramic material.The oxide-ceramic fibers and / or the oxide-ceramic matrix are composed in particular of aluminum oxide, mullite, or a mixture of aluminum oxide and mullite. According to an advantageous embodiment, the fibers can be composed of 60 to 100 wt.% aluminum oxide and 0 to 40 wt.% silicon dioxide. The matrix can in particular be composed of 70 to 100 wt.% aluminum oxide and 0 to 30 wt.% silicon dioxide.
[0010] Fiber composites with an oxide matrix are known for their high thermal (cycling) resistance, chemical resistance, and mechanical shock resistance. In particular, they demonstrate sufficient resistance at temperatures up to 1300°C. Fiber composites with an oxide matrix are also suitable for applications subject to thermal shock. The material can withstand temperature gradients of up to 1000°C / sec or 1000°C / cm. Fiber composites with an oxide matrix are also insensitive to mechanical shock loads, vibrations, and cyclic loads. When used in a battery housing cover, this material withstands the hot, particle-laden, directed gas flow escaping from a battery cell. For example, it has already been achieved that, with escaping gases at 1200°C, the temperature on the outside of the battery housing cover only reaches a maximum of 200°C through the appropriate arrangement of the fiber composite with an oxide matrix.This effectively protects surrounding vehicle parts, especially the passenger compartment, and provides enough time for vehicle occupants to leave the vehicle.
[0011] A fiber composite with an oxide matrix as described above has the further advantage that a deformable, yet flexible, flat material can be produced in its ceramic green state, which can be adapted to various surfaces. However, it can also be easily transported in a wet state and used at an application site. Fiber composites with an oxide matrix and in particular oxide-ceramic fiber composites, such as mullite composites, or composites with silicate fibers have the advantage that they are mechanically stable and transportable even in the dried, but still unsintered state (green body). In particular, the fiber composite with an oxide matrix is a nonwoven-based fiber composite with an oxide matrix and in particular a nonwoven-based oxide-ceramic composite material. In particular, it is a nonwoven made of individual ceramic fibers or a silicate nonwoven.The fibers are primarily short fibers. The advantage of these nonwovens is that they are more cost-effective than composite materials made from continuous fibers, as they can be produced from cutting waste, among other materials. Furthermore, such short-fiber nonwovens are mechanically stable and easily deformable in their green state.
[0012] Furthermore, in addition to the fiber composite with an oxide matrix as a first layer, the section can have at least one further layer. A second layer can be a thermally insulating material, such as a needle-punched nonwoven or needle-felted material. In particular, the thermally insulating fiber material is an oxide-ceramic or a mullite material made of silicon dioxide and aluminum oxide. Alternatively, it is a silica-based nonwoven. The nonwoven has, in particular, short mullite fibers that are needle-punched to form a nonwoven. The short fibers have, in particular, a length of 3 mm to 50 mm. In particular, the insulating fiber material is binder-free. The material marketed under the Maftec™ brand by Mitsubishi Chemical Corp. or the material marketed under the Fibermax™ brand by ME Schupp Industriekeramik GmbH have proven particularly suitable.The thermally insulating material is, in particular, a mat-like material containing oxide-ceramic short fibers made of Al2O3 and / or mullite. All of the above fiber materials have the advantage of being non-flammable and also inexpensive and lightweight.
[0013] A potential third layer is, in particular, a layer made of a ceramic raw material. In particular, the ceramic raw material is mullite or a milled mullite. The ceramic raw material is, in particular, a refractory material and can withstand temperatures of over 1000°C. In addition to the ceramic raw material, this third layer also comprises, in particular, an additive. The additive can be selected depending on the application and design of the third layer. In particular, the additive is an organic additive, in particular polyvinyl alcohol (PVA). Alternatively, the additive can also be water glass. Alternatively, a third layer can be a fiber composite with an oxide matrix. Such a fiber composite with an oxide matrix has, in particular, a plurality of fibers. The fibers are, in particular, oxide-ceramic multifilament fibers.Alternatively, the fibers can also be silicate fibers, in particular glass fibers, carbon, or mineral fibers. The fibers are embedded in a matrix. The fibers can be continuous fibers and / or short fibers. The third layer, comprising a fiber composite with an oxide matrix, is bonded to the second layer, in particular by means of an adhesive layer.
[0014] In a practical embodiment of the battery housing cover according to the invention, the section with the fiber composite with an oxide matrix is firmly bonded to the base body. In particular, the oxide-ceramic composite material can be glued to the base body. Suitable adhesives include conventional spray or instant adhesives. Bonding represents a simple method of bonding in this case.
[0015] Alternatively, the section containing the fiber composite with an oxide matrix can also be laminated into the base body. This is particularly possible if the base body is made of CFRP or GFRP.
[0016] A particularly cost-effective solution is when the fiber composite with an oxide matrix is non-positively attached to the base body. For example, a section of the fiber composite with an oxide matrix can be clamped to the base body or screwed to it. In this case, the section comprising the fiber composite with an oxide matrix is arranged interchangeably on the base body.
[0017] The at least one section comprising fiber composite with an oxide matrix is in particular strip-shaped. In this case, strip-shaped means that the section has a longitudinal extent at least as great as its transverse extent. In particular, the section is designed such that it extends over several outlet points of battery cells arranged in a row. A strip has in particular a width b of at least 50 mm. The length depends in particular on the arrangement of the battery cells. A strip is easy to produce and can be easily arranged on the base body. The outlet points of all battery cells arranged in a row can be covered in a single assembly step.
[0018] In particular, several individual sections are arranged on the base body. In the case of multiple rows of battery cells, these may be multiple sections, each extending across a row. However, a separate section may also be formed for each battery cell.
[0019] The production of a section comprising a fiber composite with an oxide matrix is primarily achieved by fabricating a larger section. The production of a section with the desired geometry is primarily achieved by diamond sawing, laser cutting (preferably under the exclusion of oxygen), or punching. In particular, fabrication is carried out while the section is still in its green state and, if necessary, in its wet, not yet dried state. This means that the fiber composite with an oxide matrix is not yet sintered.
[0020] In particular, the section of fiber composite with oxide matrix arranged on the base body is still in the green state.
[0021] The invention further relates to the production of a battery housing cover as described above, wherein at least one section comprising a fiber composite with an oxide matrix is arranged on a base body of the battery housing cover. Preferably, several sections are arranged on the base body. In particular, the sections are in the green state and are arranged on the base body in the green state.
[0022] The invention also relates to an arrangement of at least one battery cell in a battery housing. The battery housing surrounds the one or more battery cells and comprises, among other things, a battery housing cover, in particular a battery housing cover as described above. In particular, a plurality of battery cells are arranged in one or more rows. These can each be clamped to one another. Such an interconnected arrangement of a plurality of battery cells can also be referred to as a battery module. In particular, at least one battery module is arranged in a battery housing. The at least one battery cell has at least one outlet point.As already described above, the outlet point is a pressure relief valve or a rupture disc. In the event of excess pressure in the battery cell, for example due to a fire, a gas flow can escape from the battery cell housing in a directed and controlled manner, thus relieving the housing and dissipating heat. The section comprising a fiber composite with an oxide matrix is arranged on a side of the battery housing cover opposite the outlet point. The "opposite side" outlet point means that the section is arranged on the base body in the direction of propagation of the escaping gases, where the gas flow hits the base body of the battery housing cover.
[0023] In particular, the at least one section on the base body covers at least the area of the outlet point. Typically, the outlet point has a circular geometry, but other geometries are also conceivable. In particular, the section is designed to be large enough that—at a distance between the base body and the outlet point—it covers the base area of the gas flow's propagation cone at the level of the base body.
[0024] As already described above, at least one section extends in particular over several outlet points arranged in a row, wherein the width b of the at least one section corresponds at least to the diameter D of the outlet points. This can therefore be a strip-shaped section.
[0025] Alternatively, several individual or separate sections are arranged on the base body, with each section being opposite or extending over only one outlet point. The geometry of such an "individual section" can be rectangular or square. Alternatively, the section can have a circular geometry in order to be adapted as evenly and thus also material-efficiently to the round-shaped gas flow escaping from a pressure relief valve. In particular, the diameter or the smallest lateral extension d is at least as large as the diameter D of the outlet point. In particular, the section with its diameter D extends beyond the width B of a battery cell. Widths b of at least 25 mm for the section (individual section or strip-shaped section) have proven to be the minimum to ensure that the section adequately covers the battery housing cover.
[0026] Furthermore, the invention relates to a method for producing an arrangement as described above, wherein at least one battery cell is arranged in a battery housing, and a battery housing cover with at least one section comprising a fiber composite with an oxide matrix is arranged relative to the at least one battery cell such that the section is opposite an outlet point of the battery cell. For advantages and further features, reference is made to the above description.
[0027] The invention also relates to an electric vehicle with an arrangement as described above. An electric vehicle is an electrically powered vehicle whose drive energy is provided by at least one battery cell.
[0028] The invention also relates to the use of a section comprising fiber composite with oxide matrix and in particular comprising oxide-ceramic composite material for a battery housing cover for shielding an outer side of a battery housing cover against a gas flow caused by a battery cell.
[0029] Further practical embodiments and advantages are described below in conjunction with the figures. They show:
[0030] Fig. 1 shows an arrangement of battery cells with outlet points and a section comprising oxide-ceramic composite material in a first embodiment in a schematic representation from above,
[0031] Fig. 2 shows the arrangement of Fig. 1 in a section according to II-II of Fig. 1,
[0032] Fig. 3 shows an arrangement of battery cells with outlet points and a section comprising oxide-ceramic composite material in a first embodiment in a schematic representation from above, Fig. 4 shows an arrangement of battery cells with outlet points and a section comprising oxide-ceramic composite material in a first embodiment in a schematic representation from above, and
[0033] Fig. 5 shows the arrangement from Fig. 4 in a section according to VV from Fig. 4.
[0034] Fig. 1 shows several battery cells 10 arranged in a row. The battery cells 10 are depicted here as elongated bodies. Each battery cell 10 has an outlet point 12. The outlet point 12 is a pressure relief valve or rupture disc, through which a defined gas flow 16 (see Fig. 2 and Fig. 5, in which an outlet cone is schematically depicted) is released into the environment when the internal pressure in the battery cell 10 is high.
[0035] The battery cells 10 are covered by a battery housing cover 18, which is shown here as completely transparent. The battery housing cover 18 has a base body 20—here made of steel—on which a section 22 comprising a fiber composite with an oxide matrix is arranged. Section 22 is shown semi-transparent in Fig. 1 with a dotted area to reveal the covered outlet points 12.
[0036] From the section shown in Fig. 2 it can be clearly seen that the section 22 comprising oxide-ceramic composite material is arranged on the side of the base body 20 facing the battery cells 10.
[0037] The section 22 is strip-shaped here and extends over the outlet points 12 of battery cells 10 arranged in a row. This is therefore a purely local reinforcement of the base body 20. The width b of the strip-shaped section 22 is selected here such that it is greater than the diameter D (or the largest diagonal extension) of the outlet points 12.
[0038] As already mentioned above, in addition to the fiber composite with an oxide matrix as the first layer, section 22 can also comprise at least one further layer of a thermally insulating material. In particular, a third layer can also be provided, wherein the third layer comprises a ceramic raw material, in particular an organic additive or water glass, or is a fiber composite with an oxide matrix. For the sake of simplicity, section 22 is shown here only as a monolayer and not divided into multiple layers.
[0039] Figs. 3 and 4 show two further embodiments with sections 22 comprising a fiber composite with an oxide matrix. Several separate "individual sections" 22 are arranged on the base body 20, each extending over only one outlet point 12.
[0040] In the second embodiment according to Fig. 3, the sections 22 are square and extend only slightly further outward than the outlet points 12. This embodiment is particularly material-efficient. The width b of the sections 22 is smaller than the width B of the battery cells b, but larger than the diameter D of the outlet points 12. As an alternative to the square sections 22, circular sections 22 would also be conceivable.
[0041] In Fig. 4, several circular individual sections 22 are arranged on the base body 20. The sections 22 are dimensioned such that their diameter d is greater than the width B of a battery cell 10. This is also clearly visible in the cross-section of Fig. 5.
[0042] List of reference symbols
[0043] 10 battery cells
[0044] 12 outlet point
[0045] 16 Gas flow
[0046] 18 Battery housing cover
[0047] 20 basic bodies
[0048] 22 Section b Width of a section d Diameter of a circular section
[0049] B Width of a battery cell
[0050] D Diameter of an outlet point
Claims
Patent claims 1. Battery housing cover for covering at least one battery cell (10), with a base body (20), characterized in that at least one section (22) comprising a fiber composite with an oxide matrix is arranged on the base body (20).
2. Battery housing cover according to the preceding claim, characterized in that the section (22) is connected to the base body (20) in a materially bonded and / or force-locked manner.
3. Battery housing cover according to one of the preceding claims, characterized in that the section (22) is strip-shaped.
4. Battery housing cover according to one of the preceding claims, characterized in that several sections (22) are arranged distributed on the base body (20).
5. A method for producing a battery housing cover according to one of the preceding claims 1 to 4, wherein at least one section (22) comprising a fiber composite with an oxide matrix is arranged on a base body (20) of the battery housing cover (18).
6. Arrangement comprising a battery cell (10) in a battery housing, wherein the battery housing has a battery housing cover (18) according to one of the preceding claims 1 to 4, wherein the at least one battery cell (10) has at least one outlet point (12), characterized in that the section (22) comprising a fiber composite with an oxide matrix is arranged on a side of the battery housing cover (18) opposite the outlet point (12).
7. Arrangement according to the preceding claim, characterized in that the section (22) on the base body (20) covers at least the area of the outlet point (12).
8. Arrangement according to one of the preceding claims, characterized in that the at least one section (22) extends over several outlet points (12) arranged in a row, wherein the width (b) of the section corresponds at least to the diameter (D) of the respective outlet points (12).
9. Arrangement according to one of the preceding claims, characterized in that a plurality of sections (22) are arranged on the base body (20), wherein in each case an individual section (22) is opposite an outlet point (10) of a battery cell (12).
10. Arrangement according to the preceding claim, characterized in that the individual sections (22) each have a square or circular geometry.
11. A method for producing an arrangement according to one of the preceding claims 6 to 10, characterized in that at least one battery cell (10) is arranged in a battery housing and a battery housing cover (18) with at least one section (22) comprising a fiber composite with an oxide matrix is arranged such that the section is opposite an outlet point (12) of the battery cell (10).
12. Electric vehicle with an arrangement according to one of the preceding claims 6 to 10.
13. Use of a section (22) comprising a fiber composite with an oxide matrix for a battery housing cover (18) for shielding an outer side of the battery housing cover (18) against a gas flow caused by a battery cell (10).