WO2012072796A1

WO2012072796A1 - Battery and cover for same

Info

Publication number: WO2012072796A1
Application number: PCT/EP2011/071622
Authority: WO
Inventors: Heinz Wenzl; Gerd Niemeyer
Original assignee: Heinz Wenzl; Gerd Niemeyer
Priority date: 2010-12-02
Filing date: 2011-12-02
Publication date: 2012-06-07
Also published as: DE102010053034A1

Abstract

The invention relates to a battery (1) that comprises at least one cell (2a, 2b) containing an electrolyte, and two connection electrodes (4a, 4b), as well as a housing (3) that encloses the at least one cell. According to the invention, the housing (3) and housing cover (3b) consist, at least partially, of an electrolyte-tight and gas-permeable material.

Description

Battery and lid for this

The invention relates to a battery having at least one cell containing an electrolyte and two terminal electrodes and to a housing enclosing the at least one cell. Furthermore, the invention relates to a cover for such a battery. When operating batteries with aqueous electrolyte, but especially when charging, produces oxyhydrogen, the formation of which can not be avoided in principle. In certain designs of NiCd and NiMH cells, the resulting gas within the cell can be fully recombined if certain operating conditions are met. These cells can be built gas-tight and require a safety valve only in case the permissible operating range is left. In the case of lead acid batteries, on the other hand, for reasons of principle it can not be prevented that oxyhydrogen gas is produced. Therefore, lead-acid batteries must always have an external opening (possibly also as resealable valve).

In so-called sealed lead-acid batteries, the electrolyte is bound in a gel or fleece. The batteries are therefore electrolyte-tight and leak-proof in every position. The small amounts of gas generated during operation are blown off via a pressure relief valve. At most, during the aging of such a battery, small amounts of electrolyte can escape from the fleece or gel, so that the electrolyte tightness poses a residual problem over the entire service life.

In so-called closed lead batteries or closed NiCd or NiMH batteries, whose electrolyte is liquid, there is a fundamental Conflict between two requirements: On the one hand, the cells must have an opening so that the resulting oxyhydrogen gas can escape, since without such an opening in the housing creates an overpressure, which leads to bursting of the housing. On the other hand, the cells should be electrolyte-tight, ie even with tilting movements or short-term roll-over movements, the cells should be leak-proof. So there is a requirement for starter batteries in the car sector to ensure the electrolyte tightness under different operating conditions, eg. B. at very high currents in a fully charged battery, with tilting movements and short-term (eg., 30 minutes) positions in a lateral position or head position. In addition, the cells or batteries should be installed and operated as independent of location.

For this purpose, it is known to use a complex labyrinth in the lid area. In tilted positions of the battery, the electrolyte flows into the labyrinth, without leaking after a short time, and when recovering the initial position, the electrolyte flows back so that the electrolyte level in all cells is even again. These covers are partly made up of several parts and require complex tools. Permanent electrolyte tightness or position-independent operation is not possible with these known solutions.

For example, EP 0 834 935 B1 proposes a battery whose housing has an opening for discharging the gases emerging from the cells, a so-called flashback frit being inserted into the opening. This sieve-like frit may, for example, consist of sintered polypropylene (PP), which is permeable to gas and can delay the escape of liquid electrolyte. However, a permanent seal against electrolyte leakage can not be achieved with such frits.

In US 4,147,841 a plug is described, which consists of porous, not or poorly wettable material to one side of the inside of the To seal off the cell against the environment, but on the other hand to allow the escape of gases from the interior. However, this plug is not electrolyte-tight, so that it can not fulfill the function required here. Object of the present invention is the opposite, a battery and a lid for this purpose to provide that allow the escape of gas from the battery case, while preventing leakage of the electrolyte. This object is achieved with a battery having the features of claim 1 and a lid according to claim 10. The invention is based on the idea that the housing or the lid of the housing at least partially consists of a for at least 2.5 hours electrolyte-tight but gas-permeable material. In this way it can be ensured that, irrespective of the installation position of the battery, the resulting gas can escape while the electrolyte remains safely trapped in the housing. The term electrolyte-dense material is understood here to mean, in particular, a material from which, in the test customary for motor vehicle batteries, in which the battery is held for 30 minutes in each side position and in head position (ie a total of 2.5 hours), none Electrolyte escapes. The term gas-permeable material means in particular a material that allows at least for a short time a gas flow of 0.175 cm ³ per second and cm ² area. This is the value that can arise in the usual test for automotive batteries with a short-term overcharge of 10A. In the long term, the material should preferably be suitable for reducing the amount of blast gas produced at a typical charge current of 0.5 A over an area of a few cm ² , for example about 4 to 5 cm ² or between about 5 and 10 cm ² , leave. Thus, the permanent gas permeability is preferably at least about 0.01 cm ³ per second per cm ² area. According to a preferred embodiment of the invention, the electrolyte-tight but gas-permeable material consists of polypropylene (PP) or another durable material resistant to aqueous sulfuric acid. For example, it has been found that a polypropylene foam submerged in aqueous sulfuric acid does not undergo any electrolyte uptake with aqueous sulfuric acid over several months and is thus permanently electrolyte-tight. In another experiment, expanded polypropylene (EPP) having a specific gravity of 120 g / l and a thickness of 15 mm was loaded with an electrolyte column of about 20 mm over the 2,5 hours required in the acceptance test without any electrolyte leakage , The electrolyte-tight and gas-permeable material must also be mechanically stable due to the high mechanical stresses that a battery must withstand during its lifetime, and should also be easily connectable to the other materials of the battery case or lid. Under a polypropylene foam or foamed polypropylene here are understood not only a foam according to the classical definition, ie bubbles enclosed by solid or liquid walls, but in particular also similar to foamed polystyrene foamed foam balls. According to a particularly preferred embodiment of the invention, the electrolyte-tight and gas-permeable material is expanded polypropylene (EPP) or foamed polypropylene. This material is characterized by a good mechanical stability and is well connected to the other partially also made of polypropylene components of the battery case or cover. In addition, EPP has the property of being more easily deformable than polypropylene. This also allows the design of large parts of the battery housing or cover made of EPP, wherein, for example, the lid by means of a snap or latching connection, that is, via a clamping action, with the rest of the housing is connectable. In addition, gluing or welding the cover to the housing may result in unauthorized opening of the housing. prevent. This causes not only the advantage of improved stability of the housing but also a good electrolyte tightness between the cells.

Expanded polypropylene, especially at a density of between about 40 g / l and about 150 g / l, combines the properties of good gas permeability with simultaneous impermeability to electrolyte. Preferably, EPP having a density of more than 80 g / l is used, for example EPP having a density of about 100 g / l or about 120 g / l. A typical electrolyte is z. For example, aqueous sulfuric acid. EPP in the density ranges mentioned above is not only not wettable for such electrolytes, but also does not soak with electrolyte for a period of at least 2.5 hours, so that an EPP component remains largely dry in the long term. Here, EPP differs from, for example, sintered polypropylene or sintered Teflon which slowly soaks and is therefore not sufficiently electrolyte tight.

In order to meet the mechanical requirements for housing parts, in particular the cover of a battery housing, it is sufficient components made of EPP with a thickness of less than about 50 mm, z. B. between about 10 mm and about 45 mm, preferably between about 15 mm and about 20 mm, use. Also in terms of gas permeability, EPP components having a thickness of between about 5 mm and about 25 mm have been found to be particularly advantageous. In principle, however, even thinner components can be used. For components made of EPP significantly larger than 50 mm in the above-mentioned density range, it may be necessary to use comparatively large-area components in order to allow a sufficient passage of gas.

In a further development of the concept of the invention, it is provided that the housing has, for example, a roughly cuboidal or box-like basic body which comprises at least one base and a plurality of side walls. This basic body is preferably open on one side, around the at least one cell during installation of the battery in the housing accommodate. This opening can be closed by a lid, in particular by the lid hermetically seals the housing against the environment. If in this case at least part of the cover consists of the electrolyte-tight and gas-permeable material, the escape of gas from the battery housing is still possible.

Conventional battery cases are partially provided with an opening which connects the interior of the housing with the environment. These openings are tightly sealed by a plug during battery installation. It has proved to be particularly advantageous if such a stopper consists of the electrolyte-tight and gas-permeable material, while the rest of the housing as usual consists of a gas-impermeable material. In this way, the design of previously conventional battery case can be largely maintained and only the material of the plug of the housing is changed in order to realize the inventive effect of an electrolyte-tight and gas-permeable housing.

For cost and system reasons, cells with low capacity (up to approx. 225 Ah) are often integrated into a common housing. So it is common in starter batteries, six cells to build a 12V battery in a housing, so that the system voltage can be provided by a product in a housing. On the one hand, it is desirable if the gas produced emerges at a common opening, so that it can be removed, for example, easily and in a controlled manner via a hose. This facilitates, for example, the installation of a battery in the passenger compartment of a vehicle. However, such a construction requires a complex lid with a so-called central degassing. On the other hand, the individual cells of the battery in the installed position and during normal operation Movements electrolyte-separated from each other. If the connection between two cells of a housing, the so-called intercell connector, is not electrolyte-tight, then there arises a very high corrosion attack, which destroys the connector in a short time and makes the battery unusable.

In an electrolyte leakage at another location, the two connected via the intercell connector electrodes of two adjacent cells are high-impedance short-circuited, and discharged. From about 2 to 5 kilohms of electrolyte resistance, however, the discharge caused by it is low and is only of practical importance when considering the storage time. An electrical connection between two cells via a wetting film of appropriate length is therefore partially permitted. Zentralentgasungsdeckel based on the fact that the wetting film is thin and long, or the film is also interrupted. The partially used for battery housing polypropylene is actually not wetted by aqueous sulfuric acid. By eg oily auxiliaries and supplies from the materials and the production process, however, sulfuric acid-containing wetting films can be formed which connect electrodes of cells with high resistance. It has proved to be particularly advantageous if the housing has at least one inner wall for dividing the interior of the housing into at least two chambers, wherein the at least one inner wall consists at least partially of the electrolyte-tight and gas-permeable material. In this case, the inner wall of the housing, which consists at least partly of the electrolyte-tight and gas-permeable material, can either separate two chambers, in each of which a cell is accommodated, and / or an inner wall of the housing separates two chambers, one of which accommodates at least one of them Cell and the other is formed as connected to an opening in the housing gas outlet channel. In other words, interior walls can both be used to seal two cells electrolyte-free. nander to separate, without preventing a gas exchange, or the chamber of a cell from a communicating with the environment gas outlet channel electrolyte but gas-permeable divide. In this way, it is possible to provide only a single gas outlet opening in a battery housing with multiple cells.

The use of the electrolyte-tight and gas-permeable material is particularly suitable for batteries with a liquid electrolyte, in which the risk of leakage due to a change in position is comparatively large. However, the housing according to the invention with an electrolyte-tight and gas-permeable material can also be used for sealed batteries, in which the electrolyte is bound in a gel or nonwoven, since small amounts of electrolyte can leak out in such batteries during aging. When EPP is used as the electrolyte-tight and gas-permeable material, it is preferred if its outer surface is designed to be partially gas-permeable and partially gas-impermeable. In this way, it is, for example, possible to manufacture the lid or other parts of the housing of a battery made entirely of EPP, wherein an outlet opening for the resulting in the battery gas can be formed by the defined setting of gas-permeable areas, while other areas of the housing remain gas-impermeable , Alternatively or in addition to this, it is also possible, for example, to overmold plastic parts of a conventional battery housing with EPP or to apply EPP to such plastic parts, whereby a particularly simple connection of the electrolyte-tight and gas-permeable material to other housing components becomes possible.

The invention further relates to a cover for a battery of the abovementioned type, wherein the cover consists at least partially of an electrolyte-tight and gas-permeable material. The lid can be connected to the main body of the Battery housing can be connected by mechanical retention and / or by a bond or welding.

Regardless of the features described above, an essential aspect of the present invention relates to a battery having a plurality of cells, wherein within the battery housing, a common gas space for a plurality, especially for all, cells is provided, which preferably communicates with a gas outlet opening or has such , If the cells are so-called sealed cells in which the electrolyte is bound in gel or nonwoven, the cells need not necessarily be separated from each other with an electrolyte-tight but gas-permeable material. Rather, the cells may also have an open gas space, which marginally reduces the residual safety of aged batteries or batteries that are in lateral or head position, because then long-term electrolyte could escape from the gel or fleece.

The invention will be explained in more detail by means of embodiments and with reference to the drawings. All of the described and / or illustrated features, alone or in any meaningful combination, form the subject matter of the invention independently of their summary in the claims or their relationships.

They show schematically:

1 shows a battery according to a first embodiment of the invention,

2 shows a battery according to a second embodiment of the invention,

3 shows a battery according to a third embodiment of the invention, 4 shows a battery according to a fourth embodiment of the invention,

Fig. 5 is a section through an element of the battery according to Fig. 4 and

Fig. 6 shows a battery according to another embodiment of the invention.

The battery 1 shown in the embodiments consists of two cells 2 a, 2 b, which are accommodated in a common housing 3. Deviating from the illustrations in the exemplary embodiments, however, a battery 1 according to the invention can also have only a single cell or more than two cells.

From the housing 3 protrude two terminal electrodes 4a, 4b, which form the positive and negative pole of the battery. The two cells 2a, 2b are connected to each other in the illustrated embodiment by means of an intercell connector 5.

The housing 3 consists of an approximately box-like base body 3a, a cover 3b, which is connectable along a dashed lines in the figures shown separating plane with the main body 3a, and in multi-cell batteries at least one inner wall 3c, through which individual chambers for separate reception of the cells 2a , 2b. The electrolyte level is indicated in the drawings by a solid line above the electrode packets of the cells 2a, 2b.

In the embodiment according to FIG. 1, the main body 3a and the lid 3b of the housing 3 are made of a gas-tight material, for example polypropylene. Also, the inner wall 3c of the housing 3 is substantially formed of a gas-permeable material. However, in one above the electrolyte Mirror located portion of the inner wall 3 c, a gas-permeable region 3 d formed, which consists of an electrolyte-tight but at the same time gas-permeable material, in particular EPP. In this way, gas emerging in the left-hand cell 2a in the figure can pass into the right-hand cell 2b in the figure. In the latter, a gas outlet opening 6 is provided in the region of the cover 3b, which gas discharges from the cells 2a, 2b Gas allows. In the embodiment of Fig. 1, the lid 3b is provided for each of the cells 2a, 2b with an opening which is closed by a plug 7 gas-tight.

This embodiment allows the inventive separation of the cells of a battery with each other with a material that allows gas, electrolyte but not, with all cells 2a, 2b except one otherwise completely closed, and an unlocked cell 2b has an opening to the one Hose for gas discharge can be connected. Possibly. This opening can also be closed with gas-permeable but electrolyte-tight material in order to prevent it from tilting and to provide some re-ignition protection. For this case, a fire protection equipment of the EPP is preferably provided.

The structure of the battery according to the embodiment of Fig. 2 corresponds substantially to the structure described with reference to FIG. However, the inner wall 3c between the two cells 2a, 2b completely gas-impermeable and electrolyte-tight. In contrast, the plug 7 provided for each of the two cells in the embodiment according to FIG. 2 is made of an electrolyte-tight but gas-permeable material, in particular EPP. In this way, it is possible that gas can escape from each cell 2a, 2b, without that electrolyte can escape from the battery 1. In the embodiment according to FIG. 3, the entire cover 3b of the housing 3 is formed of the electrolyte-tight and gas-permeable material, for example EPP. Thus, from each of the cell 2a, 2b gas can be discharged into the environment. At the same time by the inner wall 3c with forming the central web of the lid 3b, which also consists of the electrolyte-tight and gas-permeable material, a gas exchange between the two cells possible. The leakage of electrolyte or the passage of electrolyte between the cells can be largely avoided in this way. In the embodiment according to FIG. 4, a further (horizontal) inner wall 8 extending approximately parallel to the parting plane between the cover 3b and the main body 3a is provided in the cover 3b, which consists of the electrolyte-tight and gas-permeable material, for example EPP. consists. As can be seen from the sectional view of this further inner wall according to FIG. 5, a groove or similar clearance is provided in the latter, which forms a gas outlet channel 8a, which is in flow connection with the gas outlet opening 6 in the housing 3. For this purpose, the inner wall 3 c, which separates the cells 2 a, 2 b from each other, also provided with an opening in the region of the gas outlet channel 8 a, so that the gas escaping from the cells can be discharged via the gas outlet opening 6. However, the electrolyte-tight material of the other (horizontal) inner wall 8 prevents electrolyte from entering the gas outlet channel. In other words, the cover 3b according to the invention in the upper region has a small opening between the cells 2a, 2b, so that a common gas space for all cells is formed, the z. B. can be connected to a gas discharge hose. With sealed batteries, this common gas space can be closed with a valve at any point in the lid 3 b. All other openings in the lid, which are required for the production process (eg for filling each cell with electrolyte) can then be closed gas-tight after production, for. B. by cell plugs or permanently by sticking or welding a plastic disc. In this way, with sealed batteries, the number of valves per battery is reduced from one per cell to one per battery.

This design allows the use of the material in the lid area with a recess directly below the lid, so that the gas from the cells can enter through the EPP in the common cell channel, which leads to a single opening of the lid and a connection facility for a central degassing system leads, which opening may optionally be additionally closed by the material used. If the possibility of topping up with water is demanded with closed batteries then obviously, but not shown here, one stopper per cell in the lid 3a and 3b can be used, which penetrates the wall 8 and after removing the possibility to fill the electrolyte with water below the Wall 8 allows.

A further embodiment of the invention is shown in Fig. 6, wherein the inner wall 3c and one of the outer walls of the main body 3a are each provided with an additional inner wall 9a, 9b of the electrolyte-tight and gas-permeable material. Also provided in the housing 3 gas outlet opening 6 is closed by a part of the additional inner wall 9b with the electrolyte-tight and gas-permeable material. This embodiment enables a position independent operation, since even with a relation to the position shown in the drawing by 180 ° rotated position of the battery, the resulting gas via the additional inner walls 9a, 9b can be transported to the adjacent cells or to the gas outlet opening 6.

Furthermore, the transfer of the idea according to the invention to sealed batteries is possible, in which the electrolyte is fixed in gel or non-woven, wherein the above-described opening of a cell for discharging the resulting Gas is closed by a valve that corresponds to the current valves of sealed batteries. Such a valve can allow gas to escape to the outside at positive pressure in the cell and possibly additionally allow air to penetrate into the battery at negative pressure in the cell.

LIST OF REFERENCE NUMBERS

1 battery

2a, 2b cell

3 housing

3a basic body

3b cover

3c inner wall

3d gas permeable area

4a, 4b connection electrode

5 intercell connectors

6 gas outlet

7 plugs

8 (horizontal) inner wall

8a gas outlet channel

9a, 9b further inner wall

Claims

Claims:

1 . Battery having at least one electrolyte-containing cell (2a, 2b) and two connection electrodes (4a, 4b) and a housing (3) enclosing the at least one cell (2a, 2b), characterized in that the housing (3) is at least partially consists of an electrolyte-tight and gas-permeable material.

2. Battery according to claim 1, characterized in that the electrolyte-tight and gas-permeable material is expanded polypropylene (EPP), in particular with a density of over about 40 g / l, or foamed polypropylene.

3. Battery according to one of the preceding claims, characterized in that the housing (3) consists of a box-like base body (3a) having a bottom and side walls, and one, in particular hermetically sealed, with this connectable lid (3b), wherein the lid (3b) consists at least partially of the electrolyte-tight and gas-permeable material.

4. Battery according to one of the preceding claims, characterized in that the housing (3) has a the interior of the housing (3) with the environment connecting opening which is closed by a plug (7) made of the electrolyte-tight and gas-permeable material.

5. Battery according to one of the preceding claims, characterized in that the housing (3) at least one inner wall (3c, 8, 9a, 9b) for dividing the interior of the housing (3) in at least two chambers on has, wherein the at least one inner wall (3c, 8, 9a, 9b) consists at least partially of the electrolyte-tight and gas-permeable material.

6. Battery according to claim 5, characterized in that the at least partially made of the electrolyte-tight and gas-permeable material

Inner wall (3c, 9a, 9b) of the housing two chambers separated from each other, in each of which a cell (2a, 2b) is received.

7. Battery according to claim 5 or 6, characterized in that the at least partially consisting of the electrolyte-tight and gas-permeable material inner wall (8) of the housing separates two chambers from each other, one for receiving at least one cell (2a, 2b) and the other as with an opening in the housing (3) connected to the gas outlet channel (8a) is formed.

8. Battery according to one of the preceding claims with a plurality of cells (2a, 2b), characterized in that in the housing (3) for at least two cells (2a, 2b), a common gas outlet opening (6) is provided.

9. Battery according to one of the preceding claims, characterized in that the electrolyte is liquid, wherein the electrolyte is optionally bound in a gel or non-woven.

10. Battery, in particular one of the preceding claims, characterized in that a plurality of cells are provided, in which electrolyte is bound in gel or nonwoven, wherein, in particular waiving the use of an electrolyte-tight but gas-permeable material in the battery case for separating the gas chambers of individual cells, in the housing for at least two cells, a common gas outlet opening is provided.

1 1. Lid for a batten according to one of the preceding claims, characterized in that the cover (3b) consists at least partially of the electrolyte-tight and gas-permeable material.