Hybrid scrim or pasting-paper material for a plate-type battery electrode of a lead-acid battery, plate-type battery electrode with such a scrim / pasting-paper material and lead-acid battery with such a battery electrode

Abstract

The invention relates to a hybrid scrim / pasting-paper material for a plate-type battery electrode (2, 3) of a lead-acid battery, in particular for a positive plate-type battery electrode (2) of a lead-acid battery (1), wherein the scrim / pasting-paper material is made in the form of a nonwoven- or woven-fabric mat and comprises the following: - fibres of a first material, which is chemically unstable, and so the fibres of the first material break up, at least substantially, when they come into contact with an electrolyte of the lead-acid battery (1), in particular during the production of the lead-acid battery (1); - fibres of a second material, which is chemically stable, at least to the extent that the fibres of the second material do not break up, or at least substantially do not break up, when they come into contact with the electrolyte of the lead-acid battery (1), in particular during the production of the lead-acid battery (1); and - optionally a binder for the fibres of the second material.

Description

[0001] Hybrid scrim or paste paper material for a plate-shaped battery electrode of a lead-acid battery, plate-shaped battery electrode with such a scrim / paste paper material, and lead-acid battery with such a battery electrode

[0002] Description

[0003] The present invention relates generally to lead-acid batteries and, more particularly, to a hybrid pasting paper material for a plate-shaped battery electrode of a lead-acid battery.

[0004] According to the current state of the art, in the manufacture of lead-acid batteries, the positive battery plates are matured and dried in batches or continuously in so-called maturing and drying chambers after the grids have been pasted with a positive active mass. The maturing process produces tribasic (3PbOPbSO4) and / or tetrabasic (4PbOPbSO4) lead sulfates from the main ingredients, namely lead oxide, water, and lead sulfate. The plates are generally stacked on pallets without any loosening. Rarely, they are placed on pallets without loosening or, in the special case of double grids with external flags, are hung loosely in racks.

[0005] To prevent the active mass from detaching from the grid, to ensure easy handling of the plates after pasting, particularly during the maturation and drying process and during battery cell assembly, and to largely prevent the plates from sticking together, it is known to apply pasting paper to the active mass after pasting the grids. In addition, the pasting paper or scrim material has the function of minimizing lead dust emissions during further processing, particularly assembly. On the other hand, the service life of a lead-acid battery in cyclic use generally depends primarily on the service life of the positive battery plates. Therefore, to increase the service life of a lead-acid battery, it is important to increase the service life of the positive battery plates.

[0006] This particularly affects the mass sludge of the positive electrode plate. Due to the volume expansion during the reaction of PbC to PbSC during a charge / discharge cycle, the positive active material detaches from the positive electrode plate, especially under long-term loads, and thus loses electrical contact with the current collector. It is therefore no longer available for generating electrical energy, so that the electrode capacity initially decreases and ultimately fails completely. The detached active material can also lead to microshort circuits at the negative electrode.

[0007] In order to improve the service life of a lead-acid battery during cyclic use, it is necessary to prevent structural changes of the positive active material due to charge and discharge, and in particular the volume expansion of the positive active material during the reaction of PbC to PbSO4.

[0008] To prevent the positive active material from expanding, it is known to apply a nonwoven or woven material to the positive electrode plate after it has been pasted. Specifically, the pasting paper / scrim material is pressed into the surface of the active mass using pressure rollers. The pressure rollers can also create a surface structure, e.g., in the form of a ripple or waffle pattern on the plate surface. In the process step where the pasting paper / scrim material is applied, it is a continuous lead strip, which is then punched / divided into individual lead plates.

[0009] The nonwoven or woven material is acid-resistant and does not dissolve, especially during the maturation process of the lead-acid battery, especially during the manufacture of the lead-acid battery, but also during subsequent use of the lead-acid battery. These are, in particular, nonwoven or woven mats containing glass fibers.

[0010] However, the prior art solutions for improving the service life of the positive battery electrode of a lead-acid battery have drawbacks. In particular, the use of nonwoven or woven mats increases the thickness and weight of the assembly. Furthermore, there is no guarantee that the positive active material of the battery electrode will be retained throughout its service life, despite the provision of such a nonwoven or woven mat made of fiberglass.

[0011] Specifically, the surface of the positive electrode loses its (metallic) strength or cohesion over the battery's lifetime under cyclic loading. The increasingly softer mass is held in the lattice by the scrim material, which is not dissolved or oxidized by the electrolyte.

[0012] Based on this problem, the invention is based on the object of providing a solution as to how mass sludge deposits of the positive electrodes can be effectively prevented even during long-term loads of a lead-acid battery.

[0013] This object is achieved according to the invention by a hybrid scrim or pasting paper material as defined in independent patent claim 1. Advantageous developments of the hybrid scrim or pasting paper material according to the invention are defined in dependent claims 2 to 20.

[0014] Accordingly, the invention relates in particular to a hybrid scrim or pasting paper material for a plate-shaped battery electrode of a lead-acid battery, in particular for a positive plate-shaped battery electrode of a lead-acid battery, wherein the scrim or pasting paper material is designed as a nonwoven or woven mat and has fibers made of a first material which is chemically unstable, so that the fibers made of the first material at least substantially dissolve upon contact with the electrolyte of the lead-acid battery, in particular during the manufacture of the lead-acid battery.

[0015] The scrim or pasting paper material according to the invention comprises, in addition to the fibers of the first, chemically unstable material, fibers of a second material that is chemically stable at least to the extent that the fibers of the second material do not dissolve, or substantially do not dissolve, upon contact with the electrolyte of the lead-acid battery, particularly during the manufacture of the lead-acid battery and preferably during use of the lead-acid battery. In addition, a binding agent is optionally used, particularly for the fibers of the second material.

[0016] Due to this composition of the scrim or pasting paper material, the nonwoven or woven mat formed from the scrim or pasting paper material has a dual function: due to the fibers from the first material, the scrim or pasting paper material serves, on the one hand, as a "classic" pasting paper, which, in the production of lead-acid batteries, allows the pasted battery grids to be stacked during the maturation and drying process of the battery plates and, after maturation, cannot adhere to each other or cannot significantly adhere to each other.

[0017] However, the fibers made of the first material gradually dissolve as soon as they come into contact with the electrolyte, which is usually about 38% sulfuric acid, and this process is accelerated by oxidation.

[0018] The fact that the positive active material is prevented from detaching from the (positive) electrode plate as a result of the volume expansion during the reaction of PbOz to PbSO4, especially during long-term loads, is due to the fibers made of the second material, which is chemically resistant to electrolyte and oxidation.

[0019] The hybrid scrim or pasting paper material according to the invention, which is preferably designed in the form of a nonwoven or woven mat, thus functions as a support structure and provides additional mechanical strength to the plate structure of the individual battery electrodes as a support structure.

[0020] The fibers made of the second material ensure uniform compression of the positive battery electrodes and, in particular, of the positive active material. The scrim or pasting paper material prevents the release of active material and, at the same time, serves as a carrier for the wet lead oxide paste during battery production. This paste is then matured and dried in the matting and drying process after the grids have been pasted. The provision of fibers made of the second, chemically resistant material ensures that the nonwoven or woven mat formed from the hybrid scrim or pasting paper material can absorb electrolyte while not being chemically attacked, or only slightly so, by the electrolyte. Thus, the scrim or pasting paper material according to the invention ensures that the positive active material is retained throughout the entire service life.It adheres to the positive active material of the positive electrode plates or is embedded in the surface structure without adhering to other substrates of the battery construction. This is crucial for the safe and effective performance of long-life batteries and batteries subject to cyclic loading.

[0021] According to preferred realizations of the hybrid scrim or pasting paper material according to the invention, it is provided that the fibers of the second material consist at least partially of a thermoplastic plastic material or comprise a thermoplastic plastic material.

[0022] Studies have shown that fibers made of polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyolefins, and / or polybutylene terephthalate (PBT / PTMT) are particularly suitable for this purpose. Fibers made of polyethylene terephthalate (PET) are particularly preferred. Furthermore, it is preferred that all fibers made of the second material be formed from a corresponding thermoplastic material.

[0023] Core-shell fibers, i.e., fibers made from different thermoplastics, are particularly suitable for this purpose. Core-shell fibers with a PET core and a PE sheath are particularly suitable. Of course, other core-shell fiber designs are also possible.

[0024] Although it is preferred that all fibers formed from the second material consist of, or at least be formed from, a thermoplastic material, in particular PET, it is also conceivable in principle for fibers to be made of another chemically resistant material, such as glass fibers. With regard to the fibers made from the first, chemically unstable material, fibers that consist at least partially of cellulose or comprise cellulose are suitable.

[0025] An optional binder is a binder from the acrylic group, in particular a binder based on polyacrylic acid and / or polymethacrylic acid.

[0026] Instead of such a binder, it is also possible to crosslink the fibers from the second material, in particular to crosslink them thermally.

[0027] The scrim or pasting paper material according to the invention has many advantages.

[0028] At least once the fibers from the first material have dissolved, the scrim or paste paper material according to the invention is a relatively lightweight material that nevertheless provides sufficient structural stability to the plate stack in battery assemblies. The scrim or paste paper material according to the invention is as homogeneous as paper, but acid-resistant. Furthermore, the scrim or paste paper material according to the invention has a reduced internal resistance due to the dissolving component.

[0029] The scrim or pasting paper material according to the invention contains little to no metals, pollutants, or chemical contaminants and is therefore non-reactive. It also does not decompose or emit carbon gas during the battery's lifetime.

[0030] The scrim or paste paper material according to the invention optimizes battery cycles without impairing other substrates in the battery assembly, which is particularly helpful during rapid discharge. Furthermore, due to the achievable low internal resistance, voltage drop at high currents and especially at cold temperatures (<0 °C) can be reduced.

[0031] In particular, it has been shown that due to the dissolution of the fibers from the first material in the scrim or pasting paper material, pores are formed that react very well to the positive active material of the electrode, thus ensuring long-lasting adhesion between the materials.

[0032] According to preferred embodiments of the scrim or pasting paper material according to the invention, it is provided that—with thermal crosslinking of the fibers from the second material—the scrim or pasting paper material comprises approximately 20 to 70 wt.% fibers of the second material. However, if a binder is used to crosslink the fibers from the second material, the proportion of fibers from the second material is approximately 20 to 40 wt.%, preferably approximately 25 to 35 wt.%, and even more preferably approximately 28 to 32 wt.%.

[0033] The scrim or pasting paper material comprises in particular about 40 to 60 wt.% fibers of the first material and preferably about 45 to 55 wt.% fibers of the first material and even more preferably about 48 to 52 wt.% fibers of the first material.

[0034] If a binder is used to crosslink the fibers of the second material, the scrim or pasting paper material should preferably comprise about 10 to 30 wt.% binder, and preferably about 15 to 25 wt.% of the binder, and more preferably about 18 to 22 wt.% of the binder.

[0035] In particular, with this composition, it can be achieved that the scrim or pasting paper material according to the invention has a relatively small thickness, so that the use of the scrim or pasting paper material has no significant effect on the thickness (or weight) of the battery electrode.

[0036] In particular, it is achievable that the hybrid scrim or pasting paper material has a thickness determined according to ISO 534 (as of the filing date) at 100 kPa pressure of only about 50 pm to 150 pm and preferably from about 70 pm to about 110 pm and even more preferably from about 85 pm to about 95 pm.

[0037] At the same time, a mass per unit area of ​​only 15 g / m 2 up to about 30 g / m 2 and preferably of about 18 g / m 2 up to about 28 g / m 2 and more preferably of about 20 g / m 2 up to about 25 g / m 2 achievable.

[0038] Studies have shown that the hybrid scrim or pasting paper material ensures optimized air permeability. In particular, the air permeability measured according to EN ISO 9237 (as of the filing date) at 2 mbar pressure is approximately 1,800 l / m 2 / s to about 2,800 l / m 2 / s and preferably about 2,000 l / m 2 / s to about 2,500 l / m 2 / s.

[0039] In the dry state, the scrim or pasting paper material according to the invention has a tensile strength or width-related breaking force of at least 0.8 N / mm, determined according to ISO 1924-2 (as of the filing date). This ensures the battery's active material's durability throughout its entire service life.

[0040] In the wet state, ie after immersion in water, the hybrid scrim or pasting paper material has a tensile strength or width-related breaking force of at least 0.5 N / mm, determined in accordance with ISO 3781 (as of the date of application).

[0041] Preferably, the fibers of the first material and the fibers of the second material are homogeneously distributed over the hybrid scrim or pasting paper material designed as a nonwoven or woven mat.

[0042] In order to ensure a certain elasticity of the fibers of the second material, while at the same time ensuring that the active material structure of the battery, in particular the positive active material of the battery electrode, is maintained throughout the entire service life, it is preferred that the fibers of the second material have an average outer diameter of about 5 pm to about 150 pm and preferably of about 10 pm to about 100 pm.

[0043] For the fibers made of the first material, tubular or hollow fibers, in particular made of cellulose or cellulose acetate, can also be used, preferably with an outer diameter in a range between approximately 50 pm to approximately 150 pm and in particular in a range between approximately 60 pm to approximately 100 pm. With this measure, the pore formation in the scrim or pasting paper material can be improved after the maturing and drying process, as a result of which particularly efficient adhesion of the scrim or pasting paper material to the positive active material is guaranteed.

[0044] For the fibers made of the first material and / or for the fibers made of the second material, fibers of limited length, in particular short fibers, continuous fibers (filaments) and / or staple fibers, are suitable.

[0045] The scrim or pasting paper material according to the invention can, in particular, have crimped fibers, preferably with 2 to 50 crimps / cm, in particular with 10 to 20 crimps / cm. Depending on the crimp of the fibers of the first material or the fibers of the second material, the fiber density in the nonwoven or woven product can be adjusted accordingly.

[0046] Alternatively or additionally, it is possible to adjust a specific surface of the fibers by selecting a corresponding cross-sectional shape of the fiber of the first and / or second material.

[0047] In addition to a circular fiber cross-section, it is particularly conceivable that the fibers of the first and / or second material have a circular, trilobal, hexagonal, polygonal, star-shaped, quadrangular, X-, K-, C-, or Y-shaped and / or irregularly shaped cross-sectional geometry.

[0048] According to embodiments of the scrim or pasting paper material according to the invention, the fibers of the second material have a diameter between 500 nm and 500 pm and preferably a diameter between 100 nm and 500 pm.

[0049] In particular, average outer diameters of 500 nm to approximately 150 pm, and preferably of approximately 5 pm to approximately 100 pm, are suitable. In particular, the fibers of the second material have a particularly average tenacity of 5 to 25 N / 5 cm on the smooth thread.

[0050] In particular for the production of nonwoven or woven mats which serve as scrim or pasting paper material for battery electrodes and in particular positive battery electrodes of a lead-acid battery, the scrim or pasting paper material can be consolidated, namely by converting a fiber nonwoven into a nonwoven fabric, in which a bond between the fibers, in particular made of the second material, is consolidated.

[0051] The fiber bond is preferably produced by frictional engagement or by a combination of frictional and positive engagement using a mechanical bonding process.

[0052] It is also conceivable that the nonwoven product is consolidated, namely by converting a fiber web into a nonwoven fabric, in which a bond between the fibers, in particular made of the second material, is consolidated, wherein the bond of the fibers is produced by means of a chemical bonding process by means of additives, in particular by means of the binder, or due to thermal energy.

[0053] The scrim or pasting paper material is preferably produced using a wet process, i.e. as a sheet formed by dewatering a fiber suspension on a screen base.

[0054] The invention further relates to a plate-shaped battery electrode for a lead-acid battery, wherein the battery electrode comprises a battery electrode grid made of a lead alloy and a lead oxide paste applied at least partially or in regions to the battery electrode grid. According to the invention, the battery electrode further comprises a nonwoven or woven mat made of a hybrid scrim or paste paper material of the type described above.

[0055] Furthermore, the invention relates to a lead-acid battery with a plurality of plate-shaped battery electrodes of the aforementioned type.

[0056] The invention is described in more detail below with reference to the accompanying drawings. They show:

[0057] FIG. 1 shows schematically and in an isometric exploded view the general structure of an exemplary embodiment of the lead-acid battery according to the invention;

[0058] FIG. 2 shows a schematic, partially sectioned, top view of a plate-shaped battery electrode of the exemplary embodiment of the lead-acid battery according to the invention shown in FIG. 1; wherein the plate-shaped battery electrode comprises a battery electrode grid made of a lead alloy and a lead oxide paste applied at least partially or in regions to the battery electrode grid; and

[0059] FIG. 3 shows a schematic plan view of the battery electrode grid of the plate-shaped battery electrode according to FIG. 2.

[0060] The lead-acid battery 1 shown schematically in an isometric exploded view in FIG. 1 has several cell elements contained in separate compartments of a housing 9 of the battery 1 with electrolyte. The lead-acid battery 1 is, in particular, a wet battery.

[0061] The individual plate-shaped battery electrodes 2, 3 comprise electrically conductive electrode grids 4. A positive paste 5 is located on the electrode grid 4 of the positive battery electrode, and a negative paste 6 is located on the electrode grid 4 of the negative battery electrode 3. The individual battery electrodes 2, 3 further comprise the hybrid scrim or pasting paper material according to the invention, which is embedded in the surfaces of the battery electrodes.

[0062] A plurality of positive plates 2 and a plurality of negative plates 3 generally form at least part of the electrochemical cell of the accumulator. Each plate set or cell may contain one or more positive plates 2 and one or more plates 3. As shown in FIG. 1, a plurality of plate sets may be electrically connected, for example, electrically connected in series, according to the capacity of the accumulator 1. The invention is not limited to the embodiment shown in the drawings, but will become apparent from a synopsis of the features disclosed herein.

[0063] Reference symbol list

[0064] 1 lead-acid battery 1 / accumulator

[0065] 2 positive battery electrode 3 negative battery electrode

[0066] 4 battery electrode grids

[0067] 5 positive active paste

[0068] 6 negative active paste

[0069] 9 housings

Claims

Patent claims 1. Hybrid scrim / paste paper material for a plate-shaped battery electrode (2, 3) of a lead-acid battery, in particular for a positive plate-shaped battery electrode (2) of a lead-acid battery (1), wherein the scrim / paste paper material is designed as a nonwoven or woven mat and has the following: Fibers made of a first material which is chemically unstable, so that the fibers made of the first material at least substantially dissolve upon contact with an electrolyte of the lead-acid battery (1), in particular during the manufacture of the lead-acid battery (1); Fibers made of a second material which is chemically stable at least to such an extent that the fibers made of the second material do not dissolve or do not dissolve substantially upon contact with the electrolyte of the lead-acid battery (1), in particular during the manufacture of the lead-acid battery (1); and optionally a binder for the fibers made of the second material.

2. Hybrid scrim / paste paper material according to claim 1, wherein the fibers of the second material consist at least partially of a thermoplastic material or comprise a thermoplastic material, wherein the thermoplastic material is preferably polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polyolefins and / or polybutylene terephthalate (PBT / PTMT).

3. Hybrid scrim / paste paper material according to claim 2, wherein the fibers of the second material are at least partially designed as core-shell fibers with a core of a first thermoplastic material and a sheath or jacket of a second thermoplastic material.

4. Hybrid scrim / paste paper material according to one of claims 1 to 3, wherein the fibers of the second material are at least partially designed as glass fibers or comprise glass fibers.

5. Hybrid scrim / paste paper material according to any one of claims 1 to 4, wherein the fibers of the first material consist at least partially of cellulose or comprise cellulose.

6. Hybrid scrim / paste paper material according to one of claims 1 to 5, wherein the binder is a binder of the acrylic group or comprises a binder of the acrylic group, wherein the binder is in particular a binder based on a polyacrylic acid and / or polymethacrylic acid.

7. The hybrid scrim / paste paper material of any one of claims 1 to 5, wherein the hybrid scrim / paste paper material comprises: about 20 to 70 wt.% fibers of the second material, and preferably about 25 to 35 wt.% fibers of the second material, and more preferably about 28 to 32 wt.% fibers of the second material; about 40 to 60 wt.% fibers of the first material, and preferably about 45 to 55 wt.% fibers of the first material, and more preferably about 48 to 52 wt.% fibers of the first material; and optionally about 10 to 30 wt.% binder, and preferably about 15 to 25 wt.% binder, and more preferably about 18 to 22 wt.% binder.

8. Hybrid scrim / paste paper material according to one of claims 1 to 7, wherein the hybrid scrim / paste paper material has a (as of the date of filing) has a thickness determined at 100 kPa pressure of from about 50 pm to 150 pm, preferably from about 70 pm to about 110 pm, and more preferably from about 85 pm to about 95 pm.

9. Hybrid scrim / paste paper material according to one of claims 1 to 8, wherein the hybrid scrim / paste paper material has a basis weight determined according to ISO 536 (as of the filing date) of about 15 g / m 2 up to about 30 g / m 2 and preferably of about 18 g / m 2 up to about 28 g / m 2 and more preferably of about 20 g / m 2 up to about 25 g / m 2 has.

10. Hybrid scrim / paste paper material according to one of claims 1 to 9, wherein the hybrid scrim / paste paper material has an air permeability of approximately 1,800 l / m, determined according to EN ISO 9237 (as of the date of application) at 2 mbar pressure. 2 / s to about 2,800 l / m 2 / s and preferably about 2,000 l / m 2 / s to about 2,500 l / m 2 / s.

11. Hybrid scrim / paste paper material according to one of claims 1 to 10, wherein the hybrid scrim / paste paper material has a tensile strength or width-related breaking force determined according to ISO 1924-2 (as of the date of application) of at least 0.8 N / mm.

12. Hybrid scrim / paste paper material according to one of claims 1 to 11, wherein the hybrid scrim / paste paper material has a tensile strength or width-related breaking force of at least 0.5 N / mm after immersion in water, as determined according to ISO 3781.

13. Hybrid scrim / paste paper material according to one of claims 1 to 12, wherein the fibers of the first material and the fibers of the second material are homogeneously distributed over the hybrid scrim / paste paper material designed as a nonwoven or woven mat.

14. Hybrid scrim / paste paper material according to one of claims 1 to 13, wherein the fibers of the second material have an average outer diameter of about 500 nm to about 150 pm, and preferably from about 5 pm to about 100 pm.

15. Hybrid scrim / paste paper material according to one of claims 1 to 14, wherein the fibers of the first material comprise tubular or hollow fibers, preferably with an outer diameter in a range between about 50 pm to about 150 pm and in particular in a range between about 60 pm to about 100 pm.

16. Hybrid scrim / paste paper material according to one of claims 1 to 15, wherein the fibers of the first material and / or the fibers of the second material are designed as fibers of limited length, in particular short fibers, as continuous fibers (filaments) and / or as staple fibers.

17. The hybrid scrim / paste paper material according to any one of claims 1 to 16, wherein the fibers of the first material comprise crimped fibers, preferably with 2 to 50 crimps / cm, in particular with 10 to 20 crimps / cm; and / or wherein the fibers of the second material comprise crimped fibers, preferably with 2 to 50 crimps / cm, and in particular with 10 to 20 crimps / cm.

18. The hybrid scrim / paste paper material of any one of claims 1 to 17, wherein the hybrid scrim / paste paper material is a mechanically formed nonwoven mat, an aerodynamically formed nonwoven mat, a hydrodynamically formed nonwoven mat, or an electrostatically formed nonwoven mat.

19. Hybrid scrim / paste paper material according to claim 18, wherein the nonwoven mat is consolidated by converting a fiber web into a nonwoven fabric, in which a bond between the fibers of the first material and / or of the second material is consolidated, wherein the bond of the fibers is produced by frictional engagement or by a combination of frictional and positive engagement by means of a mechanical bonding process.

20. Hybrid scrim / paste paper material according to claim 18, wherein the nonwoven mat is consolidated by converting a nonwoven fabric into a nonwoven fabric, in which a bond between the fibers of the first and / or second material is consolidated, wherein the The fibers are bonded together using a chemical bonding process and / or heat bonding.

21. A plate-shaped battery electrode (2, 3) for a lead-acid battery (1), wherein the battery electrode (2, 3) comprises: a battery electrode grid (4) made of a lead alloy; a lead oxide paste (5, 6) applied at least partially or regionally to the battery electrode grid; and a nonwoven or woven mat made of a hybrid scrim / paste paper material according to one of claims 1 to 20.

22. Lead-acid battery (1) having a plurality of plate-shaped battery electrodes (2, 3) according to claim 21.

Images