Storage battery cell and lead-acid storage battery

Abstract

The invention relates to a storage battery cell for a lead-acid storage battery, in particular a VRLA-AGM storage battery, having a cell housing, wherein alternating positive and negative electrode plates and an electrolyte in liquid or fleece-bonded form are arranged within the cell housing, wherein the negative electrode plates are each formed from an electrode grid and a negative active mass, and wherein the positive electrode plates are each formed from an electrode grid and a positive active mass, wherein each electrode grid is filled with the associated active mass, characterized in that the electrode grid of the positive electrode is formed from a lead-tin alloy consisting of 0.018 wt.% - 0.5 wt.% Sn, remainder Pb.

Description

[0001] Battery cell and lead-acid battery

[0002] The invention relates to a battery cell for a lead-acid battery, in particular a VRLA-AGM battery. Furthermore, the invention relates to a lead-acid battery comprising a plurality of battery cells according to the invention. Furthermore, the invention extends to various uses for the battery cell according to the invention.

[0003] Battery cells for use in lead-acid batteries are generally known from the prior art. They have a housing in which positive and negative electrode plates are arranged alternately. The electrode plates are surrounded by a liquid electrolyte, which is also arranged in the housing. Alternatively, the electrolyte can be in a bound form, such as gel or fleece. The electrode plates are each formed from an electrode grid on the one hand and a positive or negative active mass on the other. The respective electrode grid accommodates the respective active mass.

[0004] Electrode grids are usually made of a grid material in the form of a lead alloy. The grid material used can be different for the positive and negative electrodes. Lead alloys are usually referred to as electrode grid alloys.

[0005] Various factors play a role in the selection of the lead alloy. Firstly, it is necessary that the lead alloy can be processed into electrode grids in an economically viable manner. Furthermore, the lead alloy must exhibit comparatively good mechanical stability in order to be able to support both its own comparatively high weight and the weight of the electrode mass over the entire service life of the battery. Furthermore, when used as intended in a lead-acid battery, the electrode grid is constantly in contact with a highly corrosive electrolyte on the one hand and with the corrosive components of the active electrode mass on the other. Therefore, in addition to the aforementioned properties, the lead alloy must also be corrosion-resistant.

[0006] In addition, the subsequent intended use of the accumulator cell must be taken into account with regard to the required performance, in particular capacity, cycle stability and service life, which are influenced by the properties of the electrode, in particular by the choice of the electrode grid alloy.

[0007] In this context, lead-calcium-cerium-containing alloys are known, for example, from US Pat. No. 2,860,969 A. This publication addresses the problem of overcoming the disadvantages of lead-antimony alloys as electrode grid materials. Antimony was originally used in lead alloys to impart mechanical stability to the alloy. The specifically proposed PbCaSnCe-containing alloy uses calcium as a replacement for antimony to provide the necessary mechanical stability and prevent the deposition of antimony on the negative plate due to positive grid corrosion. Contamination of the negative active mass by antimony is known to lead to increased water loss due to electrolysis and sulfation of the negative plates.

[0008] The alloy component cerium, on the other hand, serves to improve corrosion properties by refining the grain size. Lattices with coarse-grained structures have webs and frames consisting of a few grains. In this case, corrosion attack at grain boundaries quickly penetrates deep into the webs or frames. This type of intergranular corrosion usually leads to premature lattice degradation.

[0009] Furthermore, lead alloys with lanthanum as an alloying component for grain size refinement have been disclosed in CN 103 762 369 A. Lanthanum is used in this alloy in weight proportions of 0.01 to 0.12%.

[0010] However, electrode grids made of the aforementioned alloys have the disadvantage that they are prone to grid growth during normal operation, which can lead to anything from a compromised positive grid ground connection to significant capacity losses in the battery. The phenomenon of grid growth is the result of a progressive loss of creep strength in the grid alloys over time. This irreversible loss of mechanical strength is a consequence of so-called "overaging" of the electrode material. Under these conditions, the increasing thickness of the corrosion layer generates an axial force that leads to significant stretching of the grid webs and frames.

[0011] Furthermore, EP 3604 576 A1 and EP 3 896 180 A1 disclose electrode grid alloys for the positive electrode. These alloys, in addition to lead as the main component, contain rare earth metals as alloying constituents and exhibit excellent properties regarding grid growth and corrosion resistance. These alloys can contain tin as an optional component.

[0012] Although the above alloys have proven themselves in practice, there is still room for improvement. This is because the rare earth elements required for battery production are often not available in sufficient quantity and quality.

[0013] Furthermore, with regard to the properties of battery cells, not only the properties of the electrode grid alloy itself must be considered. Rather, the selection of the appropriate alloy for the positive electrode grid often depends on the alloy selected for the negative electrode grid, and vice versa. Coordination can also be made with regard to other characteristics of the battery cell, such as the positive and negative active mass.

[0014] With regard to the positive active mass, it is known, for example, from EP 2 385 570 A1, to paste positive electrode plates with positive active mass. Maturation and drying steps ensure that the main ingredients—lead oxide, water, and lead sulfate—form tribasic and tetrabasic lead sulfates. Subsequently, the basic lead sulfates and lead oxide are converted to lead dioxide through the so-called formation process.

[0015] The invention is therefore based on the complex technical problem of specifying a battery cell which can be manufactured economically in industrial production, is sufficiently mechanically stable and corrosion-resistant with regard to its components and has advantageous performance-related properties.

[0016] To achieve this object, the invention proposes an accumulator cell for a lead-acid accumulator, in particular a VRLA-AGM accumulator, having a cell housing, wherein positive and negative electrode plates and an electrolyte in liquid or nonwoven form are arranged alternately within the cell housing, wherein the negative electrode plates are each formed from an electrode grid on the one hand and a negative active mass on the other hand, and wherein the positive electrode plates are each formed from an electrode grid on the one hand and a positive active mass on the other hand, wherein a respective electrode grid is filled with the respective active mass, wherein the electrode grid of the positive electrode is made of an alloy consisting of

[0017] 0.018 wt% - 0.5 wt% Sn

[0018] Rest Pb is formed.

[0019] It has been found that lead-acid batteries with battery cells according to the invention, whose positive electrode plates have an electrode grid made of the electrode grid alloy according to the invention, have excellent electrical properties, particularly with regard to capacity, cycle stability, and service life. Due to the novel alloy composition for the positive electrode grid, rare earths can be completely dispensed with as an alloy component.

[0020] The qualitative and quantitative information regarding the alloy composition always refers to the deliberately added components. Furthermore, the alloy may contain traces of other elements, whose presence, however, does not affect the properties of the alloy. The nature and quantity of these traces depend on the nature and origin of the raw materials, particularly minerals, used to produce the alloy or its components and which cannot be economically processed. These traces include, among others, Ag, As, Bi, Cu, Ni, Fe, Sb, Zn, Te, Se, Cd, Mn, Cr, and Ca.

[0021] Furthermore, the lead alloys according to the invention can be used in various processing techniques, particularly in the field of casting, rolling, and / or extrusion technology. Preferably, the lead alloys according to the invention are used as starting materials in a manufacturing process for electrode grids. In particular, these alloys can be processed to produce the electrode grid using a continuous grid strip casting process, as well as by lead strip rolling and grid strip punching, or by lead strip extrusion and punching. According to the invention, the accumulator cell has a cell housing. The cell housing provides a volume that can preferably be closed in a fluid-tight manner by means of a cell lid. In the finished accumulator cell, the cell housing is intended to accommodate the electrode plates and the electrolyte in liquid or bound, in particular gel- or fleece-bound, form.The cell housing, as well as the volume, is preferably designed with a square, particularly preferably rectangular, cross-section. In this case, the cell housing has a base and four side walls that spatially define the volume. The side walls are perpendicular to the base. Adjacent side walls are connected to each other and are at right angles to each other. Opposite side walls run parallel to each other.

[0022] According to a preferred feature of the invention, the electrode grid of the negative electrode is made of pure lead or of a lead-tin alloy consisting of

[0023] 0.01 wt% - 0.03 wt% Sn

[0024] The remainder is Pb. It has been found that the combination of positive electrode grids made of a lead-tin alloy according to the invention and negative electrode grids formed from the preferred lead-tin alloy is particularly advantageous with regard to the electrical properties of the battery cell. In particular, the capacity, cycle stability and service life of the battery cell are further improved. An alternative preferred embodiment of the negative electrode grid made of pure lead is also contemplated here. “Pure lead” in the sense of the invention refers to lead with a purity of >99.99%. It has been found that the combination of, in particular, thin, positive electrode grids made of a lead-tin alloy according to the invention and, in particular, thin, negative electrode grids made of pure lead is particularly advantageous with regard to the electrical properties of the battery cell.In particular, this improves the power density of the battery cell.

[0025] According to a preferred feature of the invention, the grid thickness of the electrode grid of the positive electrode plate is between 0.9 mm and 1.2 mm. As a result of being made from the electrode grid alloy according to the invention, the electrode grid can therefore be produced with a comparatively small material thickness. This leads to an advantageous weight reduction of the accumulator cell as a whole, without, however, negatively affecting the electrical properties of the accumulator cell. According to a preferred feature of the invention, the grid thickness of the electrode grid of the negative electrode plate is between 0.8 mm and 0.9 mm. As a result of being made from the preferred electrode grid alloy or from pure lead, the electrode grid can therefore be produced with a comparatively small material thickness.This leads to a further advantageous weight reduction of the battery cell as a whole, without, however, negatively affecting the electrical properties of the battery cell.

[0026] According to the invention, the negative electrode plates are each formed from an electrode grid on the one hand and a negative active mass on the other, and the positive electrode plates are each formed from an electrode grid on the one hand and a positive active mass on the other. The electrode grids of the negative electrode plate are filled with the negative active mass and the electrode grids of the positive electrode plate are filled with the positive active mass. The unformed positive active mass is preferably formed essentially from lead oxide, tribasic and tetrabasic lead sulfates, which are produced by means of a maturation and drying process known from the prior art from lead oxide, residual lead, residual water and basic lead sulfates. The electrode grid is initially filled with the active mass in a pasty state. This is followed by the aforementioned maturation and drying process.

[0027] Preferably, the unformed active mass of the negative plates consists essentially of lead oxide, tribasic lead sulfate, and an expander. The expander is preferably formed either from a mixture of oxylignin, barium sulfate, and carbon black or a mixture of ligninsulfonate, barium sulfate, and carbon black. The expander advantageously counteracts the shrinkage of the sponge lead during battery operation. It thus maintains the porosity of the formed negative mass, which consists of lead and lead sulfate residues.

[0028] It has been shown that particularly advantageous electrical properties of the accumulator cell can be achieved when the mass ratio of positive to negative active mass is coordinated with one another, in particular as a function of the electrode grid alloy according to the invention of the electrode grid of the positive electrode plate and the preferred grid material of the negative electrode plate. According to a preferred feature of the invention, a mass ratio between positive active mass and negative active mass of 1.15 to 1.8 is therefore provided. The mass ratio preferably relates to the dry mass of the respective active mass after the maturation, drying and formation processes have been completed. If this ratio is maintained, the capacity, cycle stability and service life of the accumulator cell are further improved, in particular in conjunction with the inventive and preferred grid materials for the respective electrode grids.

[0029] According to a preferred feature of the invention, the positive active mass accommodated by the positive electrode grid is porous. This advantageously increases the active surface area of ​​the active mass. This leads to improved electrical properties of the battery cell. The relative pore volume of the positive active mass, based on the total volume of the positive active mass of a positive electrode plate, is preferably 46% to 54%. Furthermore, the pore volume refers to the formed active mass of the positive electrode after the maturation, drying, and formation processes have been completed. For the purposes of the invention, "formation" refers to the initial electrical charge for converting the active masses into the charged state. Essentially, this means PbO + basic sulfates -> Pb (negative plate) and PbO2 (positive plate).The specified range is particularly advantageous with regard to improving the electrical properties of the accumulator cell and the mechanical stability of the positive electrode plate, in particular depending on the electrode grid alloy of the invention of the electrode grid of the positive electrode plate.

[0030] According to a preferred feature of the invention, the negative active mass accommodated by the negative electrode grid is porous. This advantageously increases the active surface area of ​​the active mass. This leads to improved electrical properties of the accumulator cell. The relative pore volume of the negative active mass, based on the total volume of the negative active mass of a negative electrode plate, is preferably 56% to 60%. Furthermore, the pore volume refers to the formed dry mass of the negative active mass after the maturation, drying, and formation process has been completed. The specified range is particularly advantageous with regard to improving the electrical properties of the accumulator cell and the mechanical stability of the negative electrode plate, particularly depending on the preferred electrode grid material of the electrode grid of the negative electrode plate.

[0031] According to a particularly preferred feature of the invention, the volume ratio between the relative pore volume of the positive active mass and the relative pore volume of the negative active mass is coordinated. This leads to particularly advantageous electrical properties of the battery cell. The volume ratio between the relative pore volume of the positively formed active mass and the relative pore volume of the negatively formed active mass is preferably 0.75 to 0.97.

[0032] According to a particular feature of the invention, the lead-tin electrode grid alloy of the positive electrode plate is made of

[0033] 0.018 wt.% - 0.22 wt.% Sn, balance Pb. Battery cells with this preferred configuration are particularly suitable for use as or as part of a stationary VRLA-AGM battery. Such batteries are intended for charge maintenance operation, as emergency power generators to maintain an uninterruptible power supply, or for mobile phone base stations. It is particularly necessary for such batteries to have a high capacity with high discharge currents and a high current consumption during charging in order to be able to adequately bridge the complete power takeover of the failed main power supply for a few minutes up to several hours and to reach the full charge state as quickly as possible during recharging. It has been shown that the current consumption is significantly improved by selecting the tin component in the specified quantity.Preferably, in combination with the specific choice of electrode grid alloy, the current consumption can be further improved. Adjusting the mass ratio between positive active mass and negative active mass to between 1.15 and 1.4 has proven effective for this purpose. Further improvements in this regard can preferably be achieved by making the positive active mass held by the positive electrode grid porous and by ensuring that the relative pore volume of the positive active mass, based on the total volume of the positive active mass of a positive electrode plate, is between 50% and 54%. The pore volume refers to the dry mass of the positive active mass after the maturation, drying, and formation process has been completed.The specified range is particularly advantageous with regard to improving the capacity of the accumulator cell and the mechanical stability of the positive electrode plate, particularly depending on the preferred electrode grid alloy of the electrode grid of the positive electrode plate. The lower limit of 0.018 wt. % forms the effectiveness threshold for the tin component. A technical effect below the lower limit was not detectable. The upper limit According to a particularly preferred embodiment of the invention, the upper specified limit for tin is preferably 0.22 wt. % in the alloy for stationary applications. An upper limit of 0.20 wt. % is particularly preferred, which leads to a further improvement in power consumption.

[0034] According to a particular alternative feature of the invention, it is provided that the lead-tin electrode grid alloy of the positive electrode plate consists of

[0035] 0.3 wt% - 0.5 wt% Sn

[0036] The remainder is Pb. Battery cells with this preferred configuration are particularly suitable for use as or as part of a VRLA-AGM traction battery. Such batteries are intended for powering vehicles, in particular off-road vehicles and / or industrial cleaning machines. In addition to the battery capacity, traction batteries must have a high cycle stability for repeated recharging during regular operation of the vehicle, in particular of the off-road vehicle. It has been shown that by selecting the tin component in the specified quantity, the cycle stability is significantly improved, especially after deep discharge. The cycle stability can preferably be further improved in combination with the special selection of the electrode grid alloy.For this purpose, setting the mass ratio between positive active mass and negative active mass to 1.5 to 1.8 has proven particularly effective. Further improvements in this respect can preferably be achieved by making the positive active mass held by the positive electrode grid porous and by the relative pore volume of the positive active mass based on the total volume of the positive active mass of a positive electrode plate being 46% to 50%. The pore volume refers to the dry mass of the positive active mass after the maturation, drying and formation process has been completed. The specified range is particularly advantageous with regard to improving the cycle stability of the accumulator cell and the mechanical stability of the positive electrode plate, particularly depending on the preferred electrode grid alloy of the electrode grid of the positive electrode plate.

[0037] The invention further relates to a lead-acid accumulator, in particular a stationary VRLA-AGM accumulator or VRLA-AGM traction accumulator, with a plurality of accumulator cells according to the invention. A VRLA accumulator (valve-regulated lead-acid battery) is a lead-acid accumulator with a sealed design. The accumulator cells and / or the accumulator as a whole can be sealed fluid-tight by using appropriate housings. The cell and / or accumulator housing in question has a pressure relief valve. The suffix AGM stands for "Absorbent Glass Mat" or "Absorptive Glass Mat" and refers to a special design of the VRLA accumulator in which the electrolyte arranged in the accumulator cell is bound in a fiberglass fleece. This fleece is arranged between the positive and negative electrode plates according to the invention.

[0038] Examples of preferred embodiments are given below.

[0039] Example 1:

[0040] A stationary VRLA-AGM battery comprising a plurality of battery cells. Each battery cell has a cell housing.

[0041] The cell housing provides a fluid-tight, sealed volumetric space with a cell cover. The cell housing provides a pressure relief valve.

[0042] Within the cell housing, positive and negative electrode plates as well as an electrolyte in fleece-bound form are arranged alternately.

[0043] The negative electrode plates are each formed by an electrode grid on the one hand and a negative active mass on the other. The positive electrode plates are each formed by an electrode grid on the one hand and a positive active mass on the other.

[0044] Each electrode grid is filled with the respective active material. The electrode grid of the positive electrode is made of an alloy consisting of

[0045] 0.018 wt% - 0.22 wt% Sn

[0046] Rest Pb formed.

[0047] The electrode grid of the negative electrode is made of pure lead or a lead-tin alloy consisting of

[0048] 0.01 wt% - 0.03 wt% Sn

[0049] Rest Pb formed.

[0050] The mass ratio between the positive active mass and the negative active mass is set at 1.15 to 1.4. The positive active mass absorbed by the positive electrode grid is porous. The relative pore volume of the positive active mass relative to the total volume of the positive active mass of a positive electrode plate is 50% to 54%. The pore volume refers to the dry mass of the positive active mass after the maturation, drying, and formation processes have been completed.

[0051] The negative active mass held by the electrode grid of the negative electrode plate is porous. The relative pore volume of the negative active mass, based on the total volume of the negative active mass of a negative electrode plate, is preferably 56% to 60%. The pore volume refers to the dry mass of the negative active mass after the maturation, drying, and formation processes have been completed.

[0052] Example 2: VRLA-AGM traction battery comprising a plurality of battery cells. Each battery cell has a cell housing.

[0053] The cell housing provides a fluid-tight, sealed volumetric space with a cell cover. The cell housing provides a pressure relief valve.

[0054] Within the cell housing, positive and negative electrode plates as well as an electrolyte in fleece-bound form are arranged alternately.

[0055] The negative electrode plates are each formed from an electrode grid on the one hand and a negative active mass on the other.

[0056] The positive electrode plates are each formed from an electrode grid on the one hand and a positive active mass on the other.

[0057] Each electrode grid is filled with the respective active material. The electrode grid of the positive electrode is made of an alloy consisting of

[0058] 0.3 wt% - 0.5 wt% Sn

[0059] Rest Pb formed.

[0060] The electrode grid of the negative electrode is made of pure lead or a lead-tin alloy consisting of

[0061] 0.01 wt% - 0.03 wt% Sn, balance Pb formed.

[0062] The mass ratio between the positive active mass and the negative active mass is set at 1.5 to 1.8. The positive active mass held by the positive electrode grid is porous. The relative pore volume of the positive active mass relative to the total volume of the positive active mass of a positive electrode plate is 46% to 50%. The pore volume refers to the dry mass of the positive active mass after the maturation, drying, and formation processes have been completed.

[0063] The negative active mass held by the electrode grid of the negative electrode plate is porous. The relative pore volume of the negative active mass, based on the total volume of the negative active mass of a negative electrode plate, is preferably 56% to 60%. The pore volume refers to the dry mass of the negative active mass after the maturation, drying, and formation processes have been completed.

Claims

Patent claims 1. Accumulator cell for a lead-acid accumulator, in particular a VRLA-AGM accumulator, with a cell housing, wherein positive and negative electrode plates and an electrolyte in liquid or nonwoven form are arranged alternately within the cell housing, wherein the negative electrode plates are each formed from an electrode grid on the one hand and a negative active mass on the other hand, and wherein the positive electrode plates are each formed from an electrode grid on the one hand and a positive active mass on the other hand, wherein a respective electrode grid is filled with the respective active mass, characterized in that the electrode grid of the positive electrode is made of a lead-tin alloy consisting of 0.018 wt% - 0.5 wt% Sn Rest Pb is formed.

2. Accumulator cell according to claim 1, characterized in that the electrode grid of the negative electrode is made of pure lead or of a lead-tin alloy consisting of 0.01 wt% - 0.03 wt% Sn Rest Pb is formed.

3. Battery cell according to claim 2, characterized by a mass ratio between positive active mass and negative active mass of 1.15 to 1.

8.

4. Accumulator cell according to claim 3, characterized in that the positive active mass received by the positive electrode grid is porous, wherein the relative pore volume of the, in particular formed, positive active mass based on the total volume of the, in particular formed, positive active mass of a positive electrode plate is 46% to 54%.

5. Accumulator cell according to claim 4, characterized in that the grid thickness of the electrode grid of the positive electrode plate is between 0.9 mm and 1.2 mm and that the grid thickness of the electrode grid of the negative electrode plate is between 0.8 mm and 0.9 mm.

6. Accumulator cell according to claim 5, characterized in that the negative active mass received by the negative electrode grid is porous, wherein the relative pore volume of the, in particular formed, negative active mass based on the total volume of the, in particular formed, negative active mass of a negative electrode plate is 56% to 60%.

7. Battery cell according to claim 6, characterized in that the volume ratio between the relative pore volume of the, in particular formed, positive active mass and the relative pore volume of the, in particular formed, negative active mass is 0.75 to 0.

97.

8. Battery cell according to one of claims 1 to 7, characterized in that the lead-tin alloy of the positive electrode consists of: 0.018 wt% - 0.22 wt% Sn Remainder Pb, wherein the mass ratio between positive active mass and negative active mass is from 1.15 to 1.4 and / or wherein the positive active mass received by the positive electrode grid is porous, wherein the relative pore volume of the formed positive active mass based on the total volume of the formed positive active mass of a positive electrode plate is 50% to 54%.

9. Battery cell according to one of claims 1 to 7, characterized in that the lead-tin alloy of the positive electrode consists of: 0.3 wt% - 0.5 wt% Sn Rest Pb, wherein the mass ratio between positive active mass and negative active mass is 1.5 to 1.8 and / or wherein the positive active mass received by the positive electrode grid is porous, wherein the relative pore volume of the formed positive active mass based on the total volume of the formed positive active mass of a positive electrode plate is 46% to 50%.

10. Lead-acid accumulator, in particular a stationary VRLA-AGM accumulator or VRLA-AGM traction accumulator, with a plurality of accumulator cells according to one of claims 1 to 9.

11. Use of a battery cell according to claim 8 as a component of a stationary VRLA-AGM battery of a system for providing an uninterruptible power supply.

12. Use of an accumulator cell according to claim 9 as a component of a VRLA-AGM traction accumulator for driving vehicles.