DE102021128950A1 - Vent Separator for a Battery Case - Google Patents

Abstract

The invention relates to a venting/separating device (100) for a battery housing, in particular a traction battery of a motor vehicle, having at least three separating stages (10, 20, 30) which are arranged so that a fluid stream (40) can flow through them in series, with at least one of the separating stages ( 20) is designed as a depth filter and at least one of the separating stages (10, 30) is designed as a surface filter. The invention also relates to a housing (20) with a ventilation separating device (100).

Description

technical field

The invention relates to a ventilation/separation device for a battery housing, in particular a traction battery of a motor vehicle, and a housing, in particular a battery housing, in particular a traction battery of a motor vehicle, for accommodating battery cells.

State of the art

Housings for accommodating electronic components, such as battery cells and the like, are usually not sealed in a completely gas-tight manner with respect to the environment. On the one hand, due to temperature fluctuations, such as heat input when charging or discharging battery cells, and on the other hand, due to naturally occurring air pressure fluctuations, especially in mobile systems, a gas exchange between the interior and exterior should be made possible. The gas exchange can prevent impermissible mechanical loads on the housing, in particular bursting or buckling of the housing. On the other hand, battery housings in particular must have an emergency ventilation function in the event of a sudden pressure increase due to battery cell failure, otherwise the housing could be damaged.

However, it is just as important that the ingress of foreign bodies, dirt and moisture in the form of liquid water is effectively prevented. Pressure compensation devices are therefore known which have semipermeable membranes, for example made of extruded polytetrafluoroethylene (PTFE), which are gas-permeable but liquid-impermeable.

Out of DE 10 2012 022 346 B4 a degassing unit for a battery housing is known which has a base body which has a gas passage opening which is covered by a semi-permeable membrane which is permeable to gases but impermeable to liquids, the membrane being connected to the base body in a stationary and fluid-tight manner, especially welded. The base body can be connected in a fluid-tight manner to a pressure equalization opening of the battery housing. The membrane ensures gas exchange during normal operation thanks to its semi-permeable properties, while to implement an emergency degassing function, an emergency degassing mandrel is arranged on a cover body, pointing towards the membrane, which perforates and tears the membrane when a limit expansion induced by internal housing pressure is exceeded, so that a sudden Pressure equalization from the interior to the environment is possible. On an inside facing towards the battery housing in an assembled state, an inner protective grid is connected to the base body, which is intended to prevent foreign objects from entering the battery housing and which supports the membrane against water pressure from the outside.

Disclosure of Invention

One object of the invention is to create a ventilation-separating device for a battery housing, in particular a traction battery of a motor vehicle, which allows rapid ventilation of the housing with little pressure loss and prevents particles from escaping.

A further object is to provide a housing, in particular a battery housing, with a ventilation separator device which allows rapid ventilation of the housing with little pressure loss and prevents particles from escaping.

According to one aspect of the invention, the aforementioned object is achieved by a ventilation/separation device for a battery housing, in particular a traction battery of a motor vehicle, with at least three separation stages, which are arranged so that a fluid stream can flow through them in series, with at least one of the separation stages being designed as a deep-bed filter and at least one of the separation stages is designed as a surface filter.

According to a further aspect of the invention, the further object is achieved by a housing, in particular a battery housing, in particular a traction battery of a motor vehicle, for accommodating battery cells, which has at least one housing opening for ventilation, the housing opening being closed by a ventilation/separation device, the Ventilation separating device has at least three separating stages, which are arranged so that a fluid stream can flow through them in series, wherein at least one of the separating stages is designed as a depth filter and at least one of the separating stages is designed as a surface filter.

Favorable configurations and advantages of the invention result from the further claims, the description and the drawing.

It is proposed according to one aspect of the invention, a ventilation separating device for a battery housing, in particular a traction battery of a motor vehicle, with at least three separation stages, which are arranged so that a fluid stream can flow through them in series. At least one of the separating stages is designed as a depth filter and at least one of the separating stages is designed as a surface filter. In other words, the subject matter of the invention is a ventilation filter for a battery housing, in particular a battery housing ventilation filter.

With a depth filter, the particle separation takes place in the depth of the filter medium. In contrast to the surface filter, the formation of a filter cake is expressly not desired with depth filtration. Unlike a surface filter, a depth filtration medium does not work according to the "sieve effect" but is based on a combination of the separation mechanisms of interception, sedimentation and diffusion.

The advantages of using a depth filter are explained in more detail below.

When battery cells explode, particles of different sizes are produced. Particles in the size range 5 to 50 μm are released from the electrode materials. Even finer are the soot particles that are produced, for example, by burning the battery cell separator. The melting of metallic components such as current collectors forms particles that are in the size range of 100 - 1,000 pm. For example, fragments of cell housings are in the millimeter size range. The separation of a wide range of particle sizes poses a major procedural challenge, since a sharp increase in pressure loss must be avoided during the separation process in order to ensure the desired gas escape from the battery housing. If pure surface filters, e.g. sieve structures, are used, the mesh size selected must be small, which can quickly lead to blocking of the filter stage. Porous depth filters, on the other hand, also separate smaller particles on fiber structures in the depth of the filter medium, with the pressure loss only gradually increasing. However, such structures can easily be blocked by large particles on the surface. Thus, the implementation of a multi-stage filtration cascade makes sense, with a surface filter first separating the large particles according to the invention, and the smaller particles separating in the deep-bed filter. The addition of a filter stage downstream of the depth filter for fine filtration is advantageous.

“Serial flow through” is used here to describe a flow-related arrangement of the individual separation stages relative to one another. In embodiments, these can be directly spatially adjacent to one another, but in other embodiments they can also be explicitly arranged at a distance from one another.

In the event of a cell defect in a vehicle battery, large quantities of gas and particles are also released, which result from the destruction of the battery cell. If large format cells are used, very large amounts of gas and particles escape. These particles can get into the environment through an existing degassing unit, which represents an additional potential hazard.

In the proposed ventilation separation device, a first separation stage can be designed, for example, as a perforated plate with grid openings of approximately 2 mm. This allows a pre-separation of large particles to be carried out. A porous metal structure, for example a metal sponge or metal foam, can be arranged behind it as a second separation stage, which works as a deep-bed filter. Significant amounts of smaller particles can also be absorbed in this metal structure. A fine filter can then follow as the third separation stage. This fine filter can be arranged, for example, on the housing wall, integrated into a degassing unit. The fine filter can also and advantageously fulfill the function of an internal protective grid.

With this ventilation separating device it can be prevented that when large amounts of particles are released, the ventilation separating device quickly becomes blocked, especially if, for example, soot is released, and that the overpressure built up in the interior of the housing cannot be reduced quickly enough.

With the proposed ventilation/separation device, passengers and/or passers-by can be protected from hot, metallic particles flying around. Furthermore, an unhindered build-up of excess pressure in the battery housing can be avoided, since the separating device clogs significantly more slowly in comparison to a simple, single-stage particle separation, for example by means of a wire mesh or a sieve structure.

Particles, in particular hot (lithium) particles, which are discharged from one or more battery cells in the event of a cell defect, can advantageously be retained by the ventilation/separation device and cannot get into the environment unhindered.

Advantageously, the ventilation separation device can include a three-stage particle separation, which pre-separation of large particles with a diameter of more than 1.0 mm via a surface filter, which separates particles via at least one depth filter and which performs further separation via a surface filter with a correspondingly small screen contour of at most 1.5 mm.

The design of the respective separating stage and the combination of the separating stages of the three-stage ventilation-separating device can essentially depend on the characteristics of the battery cell used in the housing and the structure of the battery module inside the housing.

Essentially, the depth filter ensures that the pressure loss does not become unacceptably large.

Particles with a size (smallest dimension) of at least 0.1 mm, more preferably at least 0.5 mm, even more preferably at least 0.8 mm are preferably separated off as completely as possible.

According to a favorable embodiment of the venting/separating device, a first separating stage through which the flow occurs first in a venting flow direction can be provided for coarse separating particles, and a subsequent second separating stage can be provided for depth filtration and a subsequent third separating stage can be provided for fine separating particles. It can thus be effectively avoided that the third separation stage can become clogged and an overpressure that has built up cannot be dissipated quickly enough, which could lead to damage to the housing.

According to a favorable embodiment of the ventilation separation device, the first separation stage and the third separation stage can be designed as surface filters. Particles filtered out in this way can advantageously be deposited on the surface of the separation stages and do not get any further on the ventilation flow path.

Advantageously, the ventilation separation device can be designed to be able to be arranged at least partially outside the housing when installed as intended. This advantageously saves installation space in the housing, which can be used to accommodate battery cells.

According to a favorable embodiment of the ventilation-separation device, a pressure relief valve can be provided, which releases the fluid flow from the interior of the housing to the environment when a predetermined overpressure in the housing is exceeded, with the pressure relief valve being able to flow through serially to the three separation stages.

In the event of a fault, the pressure relief valve can be used to quickly relieve excess pressure in order to prevent damage to the housing. For example, it can be a housing for lithium-ion batteries, in which gases that occur in the event of a cell defect must be discharged from the housing very quickly.

However, it is often necessary to prevent the particles that occur in the event of a fault and that escape with the gases from getting into the environment.

Furthermore, a bypass function in the form of a bypass valve can be integrated into the ventilation separator device in the event that the particles clog the separator grid to such an extent that an impermissibly high pressure would occur inside the housing.

When a predetermined overpressure in the housing is exceeded, the bypass valve opens a bypass fluid flow path from the interior of the housing to the environment, the bypass fluid flow path bypassing at least one of the separation stages.

According to a favorable embodiment of the ventilation/separation device, the pressure relief valve or bypass valve can have at least one predetermined breaking point, can be actuated by means of a pretensioned spring element and/or can have a membrane. It is also conceivable to integrate a bursting disc, which opens when there is a corresponding overpressure, into the ventilation separation device. This can be made, for example, from metal or from thermoplastic materials. If the material is sufficiently permeable to air due to a microporous structure, the ventilation-separation device can also ensure a permanent pressure equalization between the environment and the interior of the housing during normal operation.

In one embodiment of the pressure relief valve and/or bypass valve with a predetermined breaking point, the predetermined breaking point, which can be in the form of a notch or an indentation, can tear open when overpressure occurs in the housing. This results in a larger opening through which the gas produced, for example from a defective battery cell, can flow out into the environment.

In an alternative embodiment of the pressure relief valve and / or bypass valve with By means of a preloaded spring element, a valve body can compress the spring element through the excess pressure, so that a fluid path opens for rapid pressure reduction. After the overpressure has been reduced, the valve body can again contact the housing in a sealing manner, as a result of which the tightness of the housing is restored.

The separation stage designed as a depth filter can advantageously have a temperature-resistant material such as metal or ceramic.

According to a favorable embodiment of the ventilation separation device, the separation stage designed as a deep-bed filter can have a fleece, in particular a metal fiber fleece, and/or a foam, in particular a metal foam. In the case of nonwovens, the particles can be separated by the fibers of the nonwoven. In the case of foams, particle separation can take place via webs in the material. Such a three-dimensional structure of the deep-bed filter can also reliably separate particles which have a comparatively large linear expansion with a small transverse diameter.

Such a separation stage can absorb particles like in a sponge, so that the risk of separated particles clogging the vent fluid flow path is reduced. This has the effect that in the separation stage designed as a deep-bed filter, a particularly favorable ratio between the separated particle mass and the pressure loss caused by the separation can be achieved. In other words, the particle mass-related increase in pressure loss in the separation stage designed as a depth filter is flatter than in a surface filter.

In the case of a pressure gradient in the separation stage, the relationship between the differential pressure and the mass of the stored particles is advantageously formed in this way.

According to a favorable embodiment of the ventilation separation device, the separation stage designed as a depth filter can be designed in multiple stages, with a first stage of the depth filter for separating large particles, in particular at least 1 mm, and a second stage of the depth filter following in the ventilation flow direction for separating small particles, in particular at least 0.3 mm, in particular at least 0.1 mm. The deep-bed filter can thus be made up of several fleeces or sponges. In this way, particles can be absorbed in the depth filter like in a sponge, so that the risk of separated particles clogging the ventilation fluid flow path is reduced. It can thus be effectively avoided that the third separation stage can become clogged and an overpressure that has built up cannot be dissipated quickly enough, which could lead to damage to the housing.

According to a favorable embodiment of the venting/separating device, an inflow area of the separating stage designed as a deep-bed filter can be at least 15% larger than a geometric cross section of an opening of the housing provided for venting. As a result, the separating effect of the deep-bed filter can be used in a favorable manner and a rapid pressure reduction of the excess pressure in the housing can nevertheless be ensured.

According to a favorable embodiment of the ventilation separation device, the separation stage designed as a deep-bed filter can have a density gradient along a flow direction. Such a three-dimensional structure of the deep-bed filter can also reliably separate particles which have a comparatively large linear expansion with a small transverse diameter.

According to a favorable embodiment of the ventilation separation device, the separation stage designed as a surface filter can have a metal grid or metal mesh. The surface filter can advantageously be made of a metal mesh or the like, for example, in order to achieve a good separation effect.

According to a favorable embodiment of the ventilation separation device, the separation stage designed as a surface filter can be designed flat and/or have sieve structures. The surface filter can be made, for example, from a two-dimensional starting material such as sheet metal, an electrically non-conductive plate or the like. Alternatively or additionally, the surface filter can have screen structures, which can advantageously be produced by trimming or a stamping process.

Openings in the surface filter can advantageously be circular, square, slot-shaped, or rectangular, for example.

A surface filter as the first filter stage can advantageously have a smallest dimension of the openings/mesh widths of at least 1.0 mm. A surface filter as the last filter stage can advantageously have a smallest dimension of the openings/mesh widths of at most 1.5 mm.

Substantially spherical particles can thus be reliably separated. However, particles with a comparatively large longitudinal extension to a small transverse diameter can pass through a surface filter if they are aligned accordingly. An arrangement in which the last filter stage has the same or possibly a smaller mesh size can therefore make sense. However, a larger mesh size at the first separating stage is preferred in order to keep the pressure loss of the ventilation separating device and blocking of the first separating stage by accumulating particles within appropriate limits.

According to a further aspect of the invention, a housing is proposed, in particular a battery housing, in particular a traction battery of a motor vehicle, for accommodating battery cells, which has at least one housing opening for ventilation, the housing opening being closed by a ventilation-separating device according to one of the preceding claims. The ventilation separation device has at least three separation stages, which are arranged so that a fluid stream can flow through them in series. At least one of the separating stages is designed as a depth filter and at least one of the separating stages is designed as a surface filter.

In the event of a cell defect in a vehicle battery, large quantities of gas and particles are also released, which result from the destruction of the battery cell. If large format cells are used, very large amounts of gas and particles escape. These particles can get into the environment through an existing degassing unit, which represents an additional potential hazard.

In the case of the ventilation/separation device arranged in the proposed housing, a first separation stage can be designed, for example, as a perforated plate with grid openings of approximately 2 mm. This allows a pre-separation of large particles to be carried out. A porous metal structure, for example a metal sponge, can be arranged behind it as a second separation stage, which works as a depth filter. Significant amounts of smaller particles can also be absorbed in this metal structure. A fine filter can then follow as the third separation stage. This fine filter can be arranged, for example, on the housing wall, integrated into a degassing unit.

With this ventilation separating device it can be prevented that when large amounts of particles are released, the ventilation separating device quickly becomes blocked, especially if, for example, soot is released, and that the overpressure built up in the interior of the housing cannot be reduced quickly enough.

The ventilation/separation device can be used to protect passengers and/or passers-by from hot, metallic particles flying around. Furthermore, an unhindered build-up of excess pressure in the battery housing can be avoided if the separating device, in particular its last separating stage, clogs up too quickly.

Particles, in particular hot (lithium) particles, which are discharged from one or more battery cells in the event of a cell defect, can advantageously be retained by the ventilation/separation device and cannot get into the environment unhindered.

According to a favorable embodiment of the housing, the ventilation separation device can be arranged at least partially outside of the housing. The installation space in the housing can thus be used advantageously for accommodating battery cells, for example.

According to a favorable embodiment of the housing, the ventilation separation device can be arranged inside the housing. Alternatively, however, it is also possible, if the installation space within the housing is not available, to partially accommodate the ventilation/separation device outside of the housing.

According to a favorable embodiment of the housing, the housing opening can be closed by a flat, stretched-out membrane, the membrane being connected to the housing opening in a fluid-tight manner.

The membrane, which can advantageously be embodied as a semi-permeable membrane, allows gaseous media to pass through from an environment into the electronics housing and vice versa, but prevents liquid media and solids through through.

All materials which have gas permeability for ventilation during normal operation and sufficiently high impermeability to water can be used for the semipermeable membrane. Polytetrafluoroethylene (PTFE) can be used as the preferred material for the semipermeable membrane. The semi-permeable membrane has an average pore size that can range from 0.01 microns to 20 microns. The porosity is preferably about 50%; the average pore size is preferably about 10 microns.

The semipermeable membrane can preferably be designed as a film-like or film-shaped or disc-shaped, thin membrane. The gas-permeable membrane has a membrane surface which is effective for gas permeation and which can preferably have a rectangular or round outer contour on its outer circumference. However, it goes without saying that the outer circumference of the membrane can also be designed differently. The membrane is preferably a thin flat membrane, the membrane surfaces of which, which are effective for the passage of gas and point away from one another, are formed essentially parallel to one another and preferably essentially planar.

The membrane thickness of the membrane is very much smaller than its other external dimensions. The membrane can span a minimum width and/or a minimum length or a minimum external diameter of greater than or equal to 20 mm, preferably greater than or equal to 30 mm, in particular greater than or equal to 40 mm. The membrane thickness can in particular be at least 20 times, preferably at least 40 times, in particular at least 100 times smaller than the minimum width and/or the minimum length or the minimum outer diameter of the membrane. The membrane thickness can be 1 micrometer to 5 millimeters, with a membrane thickness of 0.1 to 2 mm, in particular 0.15 to 0.5 mm, being preferred.

Furthermore, the membrane can be connected, in particular welded, circumferentially to an edge of a gas passage opening of a base body, in particular a degassing unit, preferably on an inner side of the base body. Alternatively, the membrane can also be glued or held in a non-positive manner, for example clamped. The porous PTFE membrane materials described herein as being preferred can be easily welded to a plastic base body or bonded in some other way.

If the pressure in the housing suddenly increases, for example due to a defective battery cell, the membrane can be ruptured by targeted weakening, for example using an emergency degassing mandrel, so that the hot gas from the battery cell can flow out of the housing.

character list

Further advantages result from the following description of the drawing. Exemplary embodiments of the invention are shown in the drawings. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into further meaningful combinations.

• 1 eine schematische Darstellung eines Gehäuses, insbesondere Batteriegehäuses, insbesondere einer Traktionsbatterie eines Kraftfahrzeugs, zur Aufnahme von Batteriezellen, mit einer Entlüftungs-Abscheidevorrichtung mit einem Überdruckventil nach einem Ausführungsbeispiel der Erfindung;
• 2 eine schematische Darstellung der Abscheidestufen der Entlüftungs-Abscheidevorrichtung nach einem Ausführungsbeispiel der Erfindung; und
• 3 eine schematische Darstellung eines Gehäuses nach einem weiteren Ausführungsbeispiel der Erfindung ohne Überdruckventil;
• 4 eine schematische Darstellung eines Gehäuses nach einem weiteren Ausführungsbeispiel der Erfindung mit Überdruckventil und mit Umgehungsventil.

Examples show:

• 1 a schematic representation of a housing, in particular a battery housing, in particular a traction battery of a motor vehicle, for accommodating battery cells, with a ventilation-separating device with a pressure relief valve according to an exemplary embodiment of the invention;
• 2 a schematic representation of the separation stages of the vent separation device according to an embodiment of the invention; and
• 3 a schematic representation of a housing according to a further embodiment of the invention without pressure relief valve;
• 4 a schematic representation of a housing according to a further embodiment of the invention with a pressure relief valve and a bypass valve.

Embodiments of the invention

In the figures, the same or similar components are denoted by the same reference symbols. The figures only show examples and are not to be understood as limiting.

1 shows a schematic representation of a housing 50, in particular a battery housing, in particular a traction battery of a motor vehicle, for accommodating battery cells 54, with a ventilation-separating device 100 with a pressure relief valve 44 according to an exemplary embodiment of the invention. A row of battery cells 54 are shown as an example in the housing 50 .

The housing 50 has at least one housing opening for venting, which is closed by a vent separating device 100 according to one of the preceding claims. The ventilation separation device 100 has at least three separation stages 10, 20, 30, which are arranged so that a fluid flow 40 can flow through them in series. At least one of the separating stages 20 is designed as a depth filter and at least one of the separating stages 10, 30 is designed as a surface filter.

Also provided in the path of the fluid flow 40 is a pressure relief valve 44 which, as intended, opens a fluid flow path from the interior 52 of the housing 50 to the environment 60 when there is overpressure in the housing 50 . Here is the fluid flow path fluid upstream of at least one of the separation stages 10, 20, 30 arranged. The pressure relief valve 44 can have at least one predetermined breaking point and/or can be actuated by means of a preloaded spring element 46 . The spring element 46 is in 1 indicated schematically.

The ventilation/separation device 100 can be arranged entirely or at least partially outside of the housing 50 depending on the installation space specifications. Alternatively, it is also possible for the ventilation/separation device 100 to be arranged inside the housing 50 .

The housing opening of the housing 50 can be closed by a flat, stretched-out membrane, the membrane being connected to the housing opening in a fluid-tight manner. Such a preferably semi-permeable membrane can be used to equalize the internal pressure in the housing and at the same time prevent water from entering. If the internal pressure in the housing 50 suddenly increases, the membrane can rupture or be deliberately ruptured in order to enable rapid pressure reduction. In embodiments, the membrane can assume the function of the pressure relief valve 44 shown symbolically.

2 shows a schematic representation of the individual separation stages 10,20,30 of the ventilation separation device 100 according to an exemplary embodiment of the invention. An incoming fluid stream 40 is shown upstream of vent separator 100 with particulates 62 and filtered downstream of vent separator 100 .

In the ventilation/separation device 100, a first separation stage 10 through which the flow occurs first in a ventilation flow direction 42 is provided for coarse separation of particles, and a subsequent second separation stage 20 for depth filtration and a subsequent third separation stage 30 for fine separation of particles.

The first separation stage 10 and the third separation stage 30 can preferably be designed as surface filters. The separation stage 10, 30 designed as a surface filter can have a metal mesh, for example. Furthermore, the separation stage 10, 30 designed as a surface filter can be designed flat and/or have sieve structures.

The separating stage 20 designed as a deep-bed filter can advantageously have a fleece and/or a foam, in particular a metal foam. Separation stage 20, designed as a depth filter, can also be designed in multiple stages, with a first stage of the depth filter for separating large particles, in particular at least 1 mm, and a second stage of the depth filter, which follows in ventilation flow direction 42, for separating small particles, in particular at least 0.3 mm or even at least 0.1 mm. A geometric cross section of the separation stage 20 designed as a depth filter can be at least 15% larger than a geometric cross section of an opening in the housing 50 provided for ventilation. Furthermore, the separation stage 20 designed as a depth filter can have a density gradient along a flow direction, so that along the flow path in the Inside the depth filter increasingly smaller particles can be separated.

In 3 1 is a schematic representation of a housing 50 according to a further exemplary embodiment of the invention without a pressure relief valve. The other embodiment is the same as in FIG 1 illustrated embodiment. The housing 50 includes a number of battery cells 54. The fluid flow 40 that occurs in the event of a cell defect can be discharged to the environment 60 via the ventilation/separation device 100 to reduce the pressure. The vent separating device 100 can be used as in 2 be shown formed.

In the 4 shown embodiment of a housing 50 according to a further embodiment of the invention corresponds essentially to the embodiment of FIG 1 . The execution after 4 however, has a bypass valve 11 as an additional element, which opens a bypass fluid flow path 12 that bypasses the separation stages in the event that particles clog the separation stages to such an extent that an impermissibly high pressure would occur inside the housing. In the embodiment shown, the bypass fluid flow path 12 bypasses all three separation stages; however, in embodiments it is explicitly possible for only individual separation stages to be bypassed.

Reference List

10

first separation stage

11

bypass valve

12

bypass fluid flow path

20

second separation stage

30

third separation stage

40

fluid flow

42

vent flow direction

44

pressure relief valve

50

Housing

52

inner space

54

battery cells

60

Vicinity

62

particles

100

Vent Separator

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 102012022346 B4 [0004]

Claims (16)

Ventilation-separating device (100) for a battery housing, in particular a traction battery of a motor vehicle, with at least three separating stages (10, 20, 30), which are arranged so that a fluid stream (40) can flow through them in series, with at least one of the separating stages (20) acting as a deep-bed filter is designed and at least one of the separation stages (10, 30) is designed as a surface filter. Vent separator after claim 1 , wherein a first separation stage (10) through which flow occurs first in a ventilation flow direction (42) is provided for coarse separation of particles, and a subsequent second separation stage (20) is provided for depth filtration and a subsequent third separation stage (30) is provided for fine separation of particles is. Vent separator after claim 1 or 2 , wherein the first separation stage (10) and the third separation stage (30) are designed as surface filters. Vent separating device according to one of the preceding claims, wherein the vent separating device has an overpressure valve (44) which, when a predetermined overpressure in the housing (50) is exceeded, restricts the fluid flow (40) from the interior (52) of the housing (50) to the environment ( 60) releases, whereby the pressure relief valve (44) can flow through in series with the three separation stages (10, 20, 30). Vent separating device according to one of the preceding claims, wherein the vent separating device has a bypass valve (11) which, when a predetermined overpressure in the housing (50) is exceeded, creates a bypass fluid flow path (12) from the interior (52) of the housing (50) to the Environment (60) opens, wherein the bypass fluid flow path (12) bypasses at least one of the separation stages (10, 20, 30). Vent separator after claim 4 or 5 , wherein the pressure relief valve (44) or bypass valve (11) has at least one predetermined breaking point, can be actuated by means of a prestressed spring element (46) and/or has at least one rupturable membrane. Ventilation separating device according to one of the preceding claims, wherein the separating stage (20) designed as a deep-bed filter has a fleece and/or a foam, in particular a metal foam. Ventilation separating device according to one of the preceding claims, wherein the separating stage (20) designed as a depth filter is designed in multiple stages, with a first stage of the depth filter for separating large particles, in particular at least 1 mm, and a second stage of the Depth filter for the separation of small particles, in particular at least 0.3 mm, in particular at least 0.1 mm, is formed. Ventilation separating device according to one of the preceding claims, wherein an inflow area of the separating stage (20) designed as a depth filter is at least 15% larger than a geometric cross section of an opening of the housing (50) provided for ventilation. Ventilation separating device according to one of the preceding claims, wherein the separating stage (20) designed as a deep-bed filter has a density gradient along a flow direction. Ventilation separating device according to one of the preceding claims, in which the separating stage (10, 30) designed as a surface filter has a metal grid or metal mesh. Ventilation separating device according to one of the preceding claims, wherein the separating stage (10, 30) designed as a surface filter is designed flat and/or has sieve structures. Housing (50), in particular battery housing, in particular a traction battery of a motor vehicle, for accommodating battery cells, which has at least one housing opening for ventilation, the housing opening being closed by a ventilation-separating device (100) according to one of the preceding claims, the ventilation The separating device (100) has at least three separating stages (10, 20, 30), which are arranged so that a fluid stream (40) can flow through them in series, with at least one of the separating stages (20) being designed as a deep-bed filter and at least one of the separating stages (10, 30) is designed as a surface filter. housing after Claim 13 wherein the vent separator (100) is at least partially disposed outside of the housing (50). housing after Claim 13 wherein the vent separator (100) is disposed within the housing (50). Housing after one of Claims 13 until 15 , wherein the housing opening is closed by a flat, stretched-out membrane, the membrane being connected to the housing opening in a fluid-tight manner.

Images