Negative electrode for a lead-acid battery and lead-acid battery

Abstract

Negative electrode for a lead-acid battery, the negative electrode (9b) comprising: a grid (20) made of a lead alloy which does not contain antimony, and an active material paste (5) which fills the grid (20), wherein a tab (2) for electrical connection to another negative electrode (9b) is arranged at one end of the grid (20), an alloy layer (4) containing antimony is arranged at least on a central part of a surface of the grid (20), the central part corresponding to the central three-fifths of the grid (20), and the alloy layer (4) is covered with the active material paste (5) so that it is not exposed at another end of the grid (20) opposite the end at which the tab (2) is arranged.

Description

Technical area

[0001] The present invention relates to lead-acid batteries containing alloy layers in which the grid surfaces of negative electrodes partially contain antimony. State of the art

[0002] In recent years, technologies for reducing fuel consumption during stationary periods have gained attention. These technologies automatically shut down vehicle engines to improve fuel efficiency while stationary. Lead-acid batteries installed in vehicles with a fuel-saving technology are only charged while the vehicle is moving, so the depth of discharge (DOD) tends to increase. Using a lead-acid battery in an area with a high DOD poses the following two hazards.

[0003] A first danger is the promotion of detachment of a positive electrode active material from a positive electrode. During the charging / discharging of a lead-acid battery, the PbO2 in a positive electrode active material and the Pb in a negative electrode active material cause an oxidation / reduction reaction with the H2SO4 in an electrolyte, resulting in electron exchange. For example, the active materials at the positive and negative electrodes become PbSO4 after discharge, but return to PbO2 (at the positive electrode) and Pb (at the negative electrode) after charging. Each repeated charging / discharging therefore changes the crystal structures of the active materials and, in particular, reduces the bonding force in the positive electrode active material, causing the positive electrode active material to soften (i.e., soften).As the softening of the positive electrode active material progresses, the positive electrode active material gradually detaches from the positive electrode, resulting in a gradual decrease in the battery capacity. This phenomenon develops with increasing DOD. However, because this phenomenon involves a gradual increase in internal resistance, users can estimate the battery life based on the change in internal resistance.

[0004] A second danger is sudden failure due to a break in a negative electrode tab (i.e., a current collection tab). Sudden failure is a phenomenon in which charging / discharging becomes unexpectedly and suddenly impossible. A portion of the negative electrode far from the tab (i.e., a current collection mechanism) is prone to a phenomenon called sulfation, in which it is deactivated by the formation of a large PbSO4 crystal. Especially with a large DOD, this portion is noticeably inactive. When charging begins in this state, the negative electrode tab, which has a small polarization, becomes active. Repeated charging causes a sudden break in the negative electrode tab, resulting in loss of battery function.Because this phenomenon makes discharging suddenly impossible, the user cannot estimate the service life based on a change in internal resistance.

[0005] In order to eliminate the second hazard of sudden failure described above and to enable the user to easily estimate the service life, a technique described in JP 2009 - 266 514 A was proposed. Summary of the inventionProblem

[0006] JP 2009 - 266 514 A provides a lead-acid storage battery that is suitable to a certain extent for vehicles with reduced fuel consumption during stationary phases. However, it has been found that sudden failure occurs in a situation where power generation by an alternator is carried out primarily during deceleration of a motor vehicle, and accordingly, the lead-acid storage battery is exposed to a region with a larger DOD because the need for improved fuel efficiency is becoming increasingly greater. This sudden failure is not caused by the mechanism described above with reference to the second hazard, but by a mechanism unknown to date. US 2008 / 0 131 774 A1 discloses a current collector for a negative electrode of a lead-acid storage battery. US 2007 / 0 184 349 A1 discloses a lead-acid storage battery and a lead-acid storage method.US 2007 / 0 160 903 A1 discloses a lead-acid battery.

[0007] It is therefore an object of the present invention to provide a negative electrode for a lead-acid storage battery which is suitable for vehicles with a reduction in fuel consumption during stationary phases and does not cause a sudden failure even when exposed to an area with a rather large DOD, and such a lead-acid storage battery. Problem solving

[0008] The problems described above are solved by a negative electrode for a lead-acid battery according to claim 1.

[0009] The alloy layer preferably has an antimony concentration greater than or equal to 0.1 mass percent and less than or equal to 10 mass percent, and more preferably greater than or equal to 1 mass percent and less than or equal to 5 mass percent.

[0010] The alloy layer preferably has a thickness greater than or equal to 0.1 µm and less than or equal to 500 µm, and more preferably greater than or equal to 0.1 µm and less than or equal to 100 µm.

[0011] A lead-acid storage battery according to one aspect of the present invention has a configuration in which a plate pack in which the above-described negative electrode and a positive electrode having a grid made of a lead alloy and filled with an active material paste are arranged opposite to each other with a separator therebetween is accommodated in a container together with an electrolyte.

[0012] An alloy layer containing antimony may be disposed on a surface of the positive electrode grid. Advantages of the invention

[0013] A lead-acid battery according to the present invention has an extended service life by reducing the occurrence of a short circuit due to the agitation and adhesion of detached pieces of a positive electrode active material even when a discharge reaching a region with a very high DOD is frequently repeated, such as in vehicles with a reduction in fuel consumption during stationary phases. Brief description of the drawings Fig. 1 schematically shows an example of a grid used in a negative electrode for a lead-acid battery according to an embodiment. Fig. 2 schematically shows the negative electrode for the lead-acid battery according to the embodiment. Fig. 3 is a schematic cross-sectional view showing problems in the configuration of a comparative example. Fig.4 is a schematic cross-sectional view showing advantages of the embodiment. Fig. 5 schematically shows the lead-acid battery of the embodiment. Fig. Figure 6 is a diagram showing experimental results illustrating the advantages of the embodiment. Fig. Figure 7 is a diagram of experimental results illustrating the advantages of a preferred variation of the embodiment. Fig. Figure 8 is a graph of experimental results illustrating the advantages of a preferred variation of the embodiment. Description of the embodiments

[0014] Before describing various embodiments of the present invention below, it is first reported how the inventors came up with the invention.

[0015] The use of a lead-acid battery in an area with a relatively high degree of discharge (DOD) of, for example, 3% or more causes softened active material to peel off from the positive electrode during an initial period. The peeled portions of the positive electrode active material deposit at the bottom of the container. In contrast, as described in JP 2009-266514 A, the presence of an antimony-containing alloy layer on the surface of a grid (formed of a lead alloy) of the negative electrode causes the peeled portions of the positive electrode active material to be disturbed in the electrolyte and partially deposited in an upper portion of the plate pack. The peeled portions deposited in the upper portion of the plate pack are reduced to PbO2 (at the positive electrode) and Pb (at the negative electrode) during charging.In this case, the positive and negative electrodes are connected, causing an internal short circuit. This internal short circuit can cause a sudden failure. The phenomenon described above was first observed by the inventors.

[0016] The inventors conducted various studies and discovered that the formation of a local accumulator at the interface between an antimony-containing alloy layer and a grid causes gas generation along with convection, so that detached portions of the positive electrode active material tend to deposit in an upper portion of the plate pack. Based on this finding, the inventors developed a structure that prevents the interface between an antimony-containing alloy layer, which is necessary for extending the life of the negative electrode, and a negative electrode grid from being exposed and impacted even at its lowest portion, as is the case in the structure according to JP 2009-266514 A.To prevent such exposure, the interface between the alloy layer and the negative electrode grid itself in a lower part of the negative electrode grid is covered with a negative electrode active material, or the alloy layer is arranged in a position excluding the lowest part. This structure prevents exposure of the interface between the alloy layer and the grid in the lowest part of the negative electrode closest to the detached parts of the positive electrode active material, so that no gas is generated, thereby significantly reducing the possibility of the detached parts of the positive electrode active material being disturbed to an upper part of the plate pack. As a result, the occurrence of the unexpected sudden failure described above is less likely.

[0017] An embodiment of the present invention will be described below with reference to the drawings.

[0018] Fig. 1 schematically shows an example of a grid 20 used in a negative electrode 9b for a lead-acid battery according to an embodiment. Fig. Figure 2 schematically shows the negative electrode 9b for the lead-acid battery of the embodiment. Fig. The grid 20 shown in Figure 1 is an expanded metal mesh formed from a lead alloy, which may contain calcium or tin in addition to lead. The lead alloy from which the grid 20 is made does not contain antimony. Antimony is therefore not contained in the framework of the grid 20, but an antimony-containing alloy layer 4 is formed on a portion of the surface of the grid 20, which will be described further below.

[0019] A substantially diamond-shaped mesh section 3 is provided below and adjacent to an upper frame 1 provided with a tab 2. In an expanded metal grid produced using the rotary stretching process, a lower frame is provided below and adjacent to the mesh section 3. The grid 20 (and in particular the mesh section 3) is filled with an active material paste 5 to form a negative electrode 9b for the lead-acid battery. The negative electrodes 9b are electrically connected to one another via the tabs 2.

[0020] The negative electrode 9b for the lead-acid battery of the embodiment includes an antimony-containing alloy layer 4 on the surface of the grid 20, but not in a lowermost part thereof. The alloy layer 4 is not exposed at the lowermost part.

[0021] Fig.Figure 3 schematically shows an internal configuration of a lead-acid battery according to a comparative example. Fig. For the sake of simplicity, no electrolyte is shown in Figure 3. In the comparative example, a negative electrode 9b on the left side of Fig. 3, the antimony-containing alloy layer 4 is provided such that it reaches the lowest part of the negative electrode grid 20, wherein both the negative electrode grid 20 containing no antimony and the antimony-containing alloy layer 4 are exposed in the lowest part, and the boundary between the grid 20 and the alloy layer 4 is exposed to the electrolyte. A positive electrode 9a is provided on the right in Fig. 3. The positive electrode 9a is formed by filling a positive electrode grid 30 with a positive electrode active material 6. A separator 9c is arranged between the positive electrode 9a and the negative electrode 9b.

[0022] The use of the lead-acid battery in an area with a very high degree of discharge (DOD) of, for example, 3% or more causes the softened positive electrode active material 6 to peel off and deposit on the positive electrode 9a in a relatively initial period. As shown in the comparative example, if the antimony-containing alloy layer 4 is also deposited on the lowermost part of the negative electrode grid 20 as shown in Fig. 3, there is an interface between the alloy layer 4 and the negative electrode grid 20 (depicted by the dashed line A in Fig. 3) in the lowest part of the negative electrode 9b in close proximity to the deposited, detached parts 6a of the positive electrode active material 6. This interface part becomes a local accumulator. A gas generated by the local accumulator causes a (in Fig.3) convection. The detached portions 6a of the positive electrode active material 6 are transported to the upper ends of the positive electrode 9a and the negative electrode 9b by this convection and deposited thereon. As the detached portions 6a are deposited on the positive electrode 9a and the negative electrode 9b, the interelectrode distance between the positive electrode 9a and the negative electrode 9b locally decreases. The detached portions 6a of the positive electrode active material 6 deposited on the upper ends of the positive electrode 9a and the negative electrode 9b are reduced to PbO2 (at the positive electrode) and Pb (at the negative electrode) during charging. An internal short circuit occurs in the region where the interelectrode distance is locally decreased.

[0023] In the embodiment, unlike the comparative example, the alloy layer 4 is not present at the lowest part of the negative electrode grid 20, but as in Fig. 4 except for the lowest part. The interface between the alloy layer 4 and the negative electrode grid 20 is covered with the negative electrode active material paste 5 and is not exposed in the lowest part of the negative electrode 9b in close proximity to the peeled parts 6a of the positive electrode active material 6 (as shown by the dashed line B in Fig.4). This configuration prevents the generation of gas in the lowermost part of the negative electrode 9b, so that the detached parts 6a of the positive electrode active material 6 are much less likely to be transported to the upper ends of the positive electrode 9a and the negative electrode 9b by convection, thereby reducing the occurrence of sudden failure due to an internal short circuit.

[0024] The advantages of the embodiment become even more apparent when the alloy layer 4 has an antimony concentration of 0.1 mass percent to 10 mass percent, and preferably 1 mass percent to 5 mass percent. To improve rechargeability and thereby significantly extend the service life of the negative electrode 9b, the antimony concentration of the alloy layer 4 must be greater than or equal to 0.1 mass percent.

[0025] However, antimony concentrations of the alloy layer 4 greater than or equal to 10 mass percent would significantly increase the charging current, resulting in the generation of a larger amount of gas. In this case, the detached and deposited portions 6a of the positive electrode active material 6 would be more likely to be disturbed, thereby negating the advantages of the embodiment.

[0026] The advantages of the embodiment become even more apparent when the alloy layer 4 has a thickness of 0.1 µm to 500 µm, and preferably 0.1 µm to 100 µm. However, to improve rechargeability and thereby significantly extend the service life of the negative electrode 9b, the thickness of the alloy layer 4 must be greater than or equal to 0.1 µm. However, a thickness of the alloy layer 4 greater than 500 µm would significantly increase the charging current, resulting in the generation of a larger amount of gas. In this case, the detached and deposited portions 6a of the positive electrode active material 6 would be more likely to be disturbed, thereby negating the advantages of the embodiment.

[0027] Layer 4 can contain, for example, tin and / or silver in addition to lead and antimony.

[0028] The feature of the embodiment that “the antimony-containing alloy layer 4 is covered by the negative electrode active material paste 5 and is not exposed at the lowest part of the negative electrode grid 20” is not limited to the Fig. 4 (in which the alloy layer 4 is not provided only on the lower frame and the active material paste 5 is also provided on the lower frame). In particular, the alloy layer 4 may be provided on an upper part of the lower frame or may not be provided on the lower part of the mesh portion 3. A main feature of the embodiment is that the alloy layer 4 is not provided as in Fig. 3 is exposed at the lowest part of the grid 20 so that no convection occurs, and thus the grid 20 and the adjacent alloy layer 4 are not both exposed at the same time.

[0029] Fig.5 schematically shows an example of the lead-acid storage battery of the embodiment. A container 7 is an integrated product molded from a synthetic resin, including a partition wall 7a for dividing the interior of the container 7 into a plurality of cell compartments 8, a shorter side surface 7b, a longer side surface 7c, and a bottom surface (not shown). Each of the cell compartments 8 contains an electrolyte (not shown) and a plate pack 9 in which a positive electrode 9a and a negative electrode 9b of the embodiment are placed opposite to each other with a separator 9c interposed therebetween. The tabs (reference numeral 2 in the case of the negative electrode) of the electrode plates having the same polarity (i.e., the positive electrode 9a or the negative electrode 9b) are connected to a connecting part 10.The respective connecting parts 10 for different polarities, to which adjacent plate packs 9 are connected, are brought into contact with each other via through holes provided in the partition walls 7a, and where the connecting parts 10 are in contact with each other, they are subjected to resistance welding under predetermined conditions. The tabs 2 of the positive electrodes 9a of the cell compartment 8 are connected at one end to a positive terminal (not shown), and the tabs 2 of the negative electrodes 9b of the cell compartment 8 are connected at the other end to a negative terminal (not shown). The opening of the container 7 is covered by a lid 11, and the terminals are connected to sleeves (not shown) integrated into the lid 11 to form terminals 12. In this way, the lead-acid storage battery of the embodiment is constructed.

[0030] The use of the positive electrode 9a in which an antimony-containing alloy layer is provided on the surface of the grid 30 to increase the conductivity at the interface between the grid 30 and the positive electrode active material 6 can further improve the performance of the lead-acid battery of the embodiment. [Examples]

[0031] In the following, advantages of the embodiment are explained using an example.

[0032] Lead oxide powder was kneaded with sulfuric acid and purified water to form a positive electrode active material paste 6. The positive electrode active material paste 6 was filled into a positive electrode grid 30 obtained by stretching a rolled sheet (made of a lead-calcium alloy) with a surface on which an alloy layer containing lead, tin, and antimony was disposed, by a reciprocating motion. Thus, a positive electrode 9a was formed.

[0033] Furthermore, lead oxide powder, to which an organic additive, barium sulfate, carbon, etc., were added by a well-known process, was kneaded with sulfuric acid and purified water to form a negative electrode active material paste. The negative electrode active material paste was filled into a negative electrode grid 20 obtained by stretching a rolled sheet (made of a lead-tin-calcium alloy) with a surface on which an alloy layer 4 containing lead, tin, and antimony was disposed under various conditions (described below) by a reciprocating motion. Thus, a negative electrode 9b (with a length of 115 mm) was produced. The rolled sheet did not contain antimony.

[0034] The positive and negative electrodes 9a and 9b were cured and dried. Then, the positive electrodes 9a were wrapped in bag-shaped polyethylene separators 9c, and the positive electrodes 9a and the negative electrodes 9b were alternately stacked. Thereafter, the tabs 2 of the positive and negative electrodes 9a and 9b were welded to connecting parts 10 to obtain a plate pack 9. The plate pack 9 was inserted into each of six cell compartments 8 of the container 7. The connecting parts 10 were welded together via through holes provided in the partition walls 7a to connect the plate packs 9.

[0035] Thereafter, the lid 11 was attached to the container 7 and poles were welded to the sleeves to form terminals 12. Finally, an electrolyte consisting of dilute sulfuric acid was poured into the cell compartments 8, the specific gravity of the electrolyte being 1.280 g / cm 3(corresponding to a value obtained at 20 °C). In this way, a 12 V, 48 Ah lead-acid battery was produced.

[0036] A study was conducted in three phases. In an initial phase, in order to determine the application range of the embodiment, a study was conducted on where to place the alloy layer 4 on the surface of the grid 20, with the antimony concentration of the alloy layer 4 being fixed at 2 mass percent and the thickness of the alloy layer 4 being fixed at 10 µm. Table 1 shows these conditions. In Table 1, the "upper part", the "lower part", and the "middle part" of the grid refer to five parts obtained by distributing the grid in the vertical direction as shown in Fig.1. Specifically, the "upper part" is the uppermost fifth. Furthermore, the "lower part" is an area obtained by subtracting the "lowest part" described below from the lowest fifth. The "middle part" corresponds to the middle three-fifths. The "lowest part" is an area extending upwards from the bottom of the grid by 5 mm. [Table 1] sample Description note upper part middle part lower part bottom part Nr. 1 unavailable available unavailable unavailable Example Nr. 2 available available unavailable unavailable ↑ Nr. 3 available available available unavailable ↑ Nr. 4 unavailable unavailable unavailable available Comparison example Nr. 5 available available available available ↑

[0037] In a second phase, to determine an optimal application range for the embodiment, an area where the alloy layer 4 was provided on the surface of the grid 20 was defined as "any part except the lowest part," with the antimony concentration of the alloy layer 4 being varied and the thickness of the alloy layer 4 being fixed at 10 µm. Table 2 shows these conditions. [Table 2] sample Sb-Conc. Description note upper part middle part lower part bottom part Nr. 6 0, 1 unavailable available available unavailable Example Nr. 7 10 unavailable available available unavailable ↑ Nr. 8 0,05 available available available unavailable ↑ Nr. 9 0,1 available available available unavailable ↑ Nr.10 1 available available available unavailable ↑ Nr.11 2 available available available unavailable ↑ Nr.12 5 available available available unavailable ↑ Nr.13 10 available available available unavailable ↑ Nr.14 15 available available available unavailable ↑

[0038] In a third phase, to determine an optimal application range for the embodiment, a range where the alloy layer 4 was provided on the surface of the grid 20 was set to "any part except the lowest part," with the antimony concentration of the alloy layer 4 fixed at 2 mass percent and the thickness of the alloy layer 4 varied. Table 3 shows these conditions. [Table 3] sample Thickness of the Sb layer Description note upper part middle part lower part bottom part Nr.15 0,1 µm unavailable available available unavailable Example Nr.16 500 µm unavailable available available unavailable ↑ Nr.17 0,01 µm available available available unavailable ↑ Nr.18 0,1 µm available available available unavailable ↑ Nr.19 1 µm available available available unavailable ↑ Nr.20 10 µm available available available unavailable ↑ Nr.21 100 µm available available available unavailable ↑ Nr.22 500 µm available available available unavailable ↑ Nr.23 750 µm available available available unavailable ↑

[0039] For each of the batteries shown in Tables 1-3, a life test was conducted for a specification of no-load stops under controlled charging conditions. Specifically, a pattern modified from the Standard of Battery Association (SBA S 0101) was used as described below. At an air temperature of 25°C ± 2°C (with a wind speed of 2.0 m / s or less near the lead-acid battery), a series of "Processes A → B" described below was performed once, and then a series of "Processes C → D" was performed four times, and this pattern was defined as one cycle. Process E was performed once every 50 cycles. In the following list, α is an actually measured value (%) of a DOD calculated from the total discharge (i.e., the total discharged electrical quantity) in processes A and C in one cycle and the rated capacity of the lead-acid battery. A. Discharge with 48 A for (24 × α) s B. Discharging with 300 A for 1 s C. Discharging with 48 A for (3 × α) s D. Charging (with a constant voltage of 14.5 V) with a limiting current of 72 A for (6 × α) s. E. Charging (with a constant voltage of 14.5 V) with a limit current of 72 A, carried out until attenuation to 5 A.

[0040] The battery was allowed to rest for 40-48 hours after every 3600 cycles. The number of cycles in which the discharge voltage fell below 7.2 V in process B was used to determine the service life. Fig. Figure 6 shows a lifetime experiment with different DODs using accumulators Nos. 1-5. Fig. Figure 7 shows a lifetime experiment for the case of a DOD of 3% using accumulators Nos. 6-14. Fig. Figure 8 shows a lifetime experiment for the case of a DOD of 3% using accumulators Nos. 15-23.

[0041] As in Fig. 6, lead-acid batteries Nos. 1-3, in each of which an antimony-containing alloy layer 4 was disposed on the surface except for the lowest part of the grid 20, exhibited excellent cycle life characteristics even when the charging possibilities were controlled and the DOD was increased to 3%, and thus differed from lead-acid batteries Nos. 4-5, in each of which an antimony-containing alloy layer 4 was disposed on the surface including the lowest part of the grid 20. A comparison between batteries 6-14 with regard to the composition of the alloy layer 4 ( Fig. 7) and between the accumulators 15-23 with regard to the thickness of the alloy layer 4 ( Fig.8) at a constant DOD of 3% shows that antimony concentrations greater than or equal to 0.1 mass percent and less than or equal to 10 mass percent (preferably greater than or equal to 1 mass percent and less than or equal to 5 mass percent) or thicknesses greater than or equal to 0.1 µm and less than or equal to 500 µm (preferably greater than or equal to 0.1 µm and less than or equal to 100 µm) can achieve greater advantages of the present invention and can further extend the service life of the battery.

[0042] In this example, the "bottommost part" is a region extending 5 mm upward from the lower end of the grid 20 (i.e., the lowest 1 / 23 of the total length of 115 mm). Alternatively, the "bottommost part" in this example can of course be any other region, as long as the interface between the grid 20 and the alloy layer 4 is not present at the lowest part of the grid 20. Based on the result in which Samples Nos. 1 and 2 exhibit sufficient properties, the lowest part should preferably be within 1 / 5 of the lower end of the grid 20 when the grid 20 is divided into five equal parts in the vertical direction. (Other embodiments)

[0043] The above-described embodiment is merely an example of the present invention, and the present invention is not limited to the above-described embodiment. The embodiment may be combined with, and partially replaced by, well-known techniques, conventional techniques, and / or publicly known techniques. Those skilled in the art may make various modifications to the embodiments described herein without departing from the scope of the invention.

[0044] The mesh shape of the negative electrode grid 20 is not limited to a diamond shape, but can also be rectangular or circular. Any known material with any composition can be used for the negative electrode grid 20, the positive electrode grid 30, the negative electrode active material, and the positive electrode active material 6. The sizes of the negative and positive electrodes 9a, 9b are not limited to those described in the example. Industrial applicability

[0045] A lead-acid battery according to the present invention has excellent cycle life characteristics in an environment with frequently repeated deep discharges in which idle stops are performed while controlling charging opportunities, so that the lead-acid battery is extremely useful for industrial use. List of reference symbols 1 upper frame 2 tabs 3 stitch sections 4 alloy layer 5 negative electrode active material paste 6 positive electrode active material 6a detached parts of the positive electrode active material 7 containers 7a Partition wall 7b shorter side surface 7c longer side surface 8 cell compartment 9 record pack 9a positive electrode 9b negative electrode 9c Separator 10 Connecting part 11 lids 12 connection 20 negative electrode grid 30 positive electrode grid

Claims

[1] Negative electrode for a lead-acid battery, the negative electrode (9b) comprising: a grid (20) made of a lead alloy which does not contain antimony, and an active material paste (5) which fills the grid (20), wherein a tab (2) for electrical connection to another negative electrode (9b) is arranged at one end of the grid (20), an alloy layer (4) containing antimony is arranged at least on a central part of a surface of the grid (20), the central part corresponding to the central three-fifths of the grid (20), and the alloy layer (4) is covered with the active material paste (5) so that it is not exposed at another end of the grid (20) opposite the end at which the tab (2) is arranged. [2] The negative electrode according to claim 1, wherein the alloy layer (4) has an antimony concentration greater than or equal to 0.1 mass percent and less than or equal to 10 mass percent. [3] The negative electrode according to claim 2, wherein the alloy layer (4) has an antimony concentration greater than or equal to 1 mass percent and less than or equal to 5 mass percent. [4] The negative electrode according to claim 1, wherein the alloy layer (4) has a thickness greater than or equal to 0.1 µm and less than or equal to 500 µm. [5] A negative electrode according to claim 4, wherein the alloy layer (4) has a thickness greater than or equal to 0.1 µm and less than or equal to 100 µm. [6] A lead-acid storage battery, wherein a plate pack (9) in which the negative electrode (9b) according to any one of claims 1-5 and a positive electrode (9a) having a grid (30) made of a lead alloy and filled with an active material paste (6) are arranged opposite each other with a separator (9c) therebetween, is accommodated in a container (7) together with an electrolyte. [7] A lead-acid storage battery according to claim 6, wherein an alloy layer containing antimony is disposed on a surface of the grid (30) of the positive electrode (9a).

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