JP2016189260A - Lead acid storage battery - Google Patents

Abstract

CONSTITUTION: In a lead acid storage battery, the theoretical capacity of an electrolyte is 30% or more of the theoretical capacity of a negative electrode material, and the negative electrode material contains more than 0 and less than 0.6 mass% of barium sulfate and has a density of higher than 3.6 g/cm.EFFECT: In a lead acid storage battery, deep discharge with a negative electrode utilization ratio of 30% or more can be repeated, so that an operating time of a fork lift per cycle can be prolonged.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lead-acid battery, and particularly to a lead-acid battery having a long life even when repeatedly discharged deeply.

There is a desire to increase the operating hours per day of a forklift, and in order to respond to this from the side of lead-acid batteries, it is necessary to improve the life performance when repeated deep discharge. Patent Document 1 (JP2013-218894A) uses acid-type lignin sulfonic acid instead of sodium salt, the density of the negative electrode material is 3.7 g / cm ³ or more, and the electrode material contains 0.2 to 1.2 mass% carbon. Thus, it is disclosed that the life performance is improved. Patent Document 1 discloses an example in which the barium sulfate concentration in the negative electrode material is 0.6 mass%.

  Patent Document 2 (JP2010-529619A) discloses a preferred composition of the negative electrode material for each use of the lead storage battery. In industrial power for forklifts and the like, it is said that barium sulfate is contained at a high concentration of 1.4 to 2.25 mass%, compared to automobiles and the like. This suggests that there is an empirical rule that a high concentration of barium sulfate is effective for repeated deep discharges.

JP2013-218894A JP2010-529619A

  The subject of this invention is improving the lifetime performance of a lead acid battery with respect to the cycle which repeats deep discharge.

The lead acid battery of the present invention has a theoretical capacity of the electrolyte of 30% or more of the theoretical capacity of the negative electrode material, the negative electrode material contains barium sulfate of more than 0 and less than 0.6 mass%, and further the density of the negative electrode material Is higher than 3.6 g / cm ³ . Preferably, the theoretical capacity of the electrolytic solution is 40% or more of the theoretical capacity of the negative electrode material.

When the negative electrode material contains more than 0 and less than 0.6 mass% barium sulfate, and the density of the negative electrode material is higher than 3.6 g / cm ^{3, the} amount of electricity corresponding to 30% or more of the theoretical capacity of the negative electrode material Even if it is repeatedly discharged, the capacity can be maintained high (FIGS. 1 to 3). Hereinafter, the discharge of the electric quantity corresponding to 30% or more of the theoretical capacity of the negative electrode material is referred to as “discharge where the utilization rate of the negative electrode material is 30% or more” or “discharge where the utilization rate of the negative electrode is 30% or more”. It may be expressed as follows. There is an empirical rule that high barium sulfate content is better for applications involving deep discharge (see, for example, Patent Document 2), and making the barium sulfate content less than 0.6 mass% exceeds this empirical rule. It is. In addition, the fact that a combination of a specific barium sulfate content and a negative electrode material density higher than 3.6 g / cm ³ is important is a finding obtained for the first time in the present invention. For example, in Patent Document 1, the combination of the carbon content and the density of the negative electrode material is important.

  In the lead storage battery of the present invention, since the theoretical capacity of the electrolyte is 30% or more of the theoretical capacity of the negative electrode material, it is possible to perform a deep discharge such as a discharge in which the utilization factor of the negative electrode material is 30% or more. . In this battery, the capacity of the electrolytic solution can be increased as compared with that having a theoretical capacity of less than 30% of the theoretical capacity of the negative electrode material. The theoretical capacity of the electrolytic solution is preferably 40% or more of the theoretical capacity of the negative electrode material. This is because the amount of sulfuric acid component remaining when the discharge reaction proceeds increases, so that an increase in reaction overvoltage caused by a decrease in the sulfuric acid concentration in the electrolyte is suppressed, resulting in a further increase in the lead storage battery. This is because capacity can be increased. Since this effect is excellent, the theoretical capacity of the electrolytic solution is preferably 43% or more, more preferably 57% or more of the theoretical capacity of the negative electrode material. Since the lead-acid battery of the present invention has a long life even when repeated deep discharge is performed, the operation time per cycle can be increased when a lead-acid battery for forklifts, electric cars, etc. is used.

When the negative electrode material has a barium sulfate content and density satisfying any one of the following ranges, the life of the negative electrode material after repeated deep discharges can be extended.
i) Barium sulfate content is greater than 0.1 mass% and density is greater than 3.7 g / cm ³ ,
ii) Barium sulfate content is greater than 0.2 mass% and density is higher than 3.6 g / cm ³

If the content of barium sulfate and the density of the negative electrode material satisfy any one of the following ranges, the life when deep discharge is repeated can be further increased.
i) barium sulfate content of less 0.15 mass% or more 0.5 mass%, and density of 3.8 g / cm ³ or more 4.0 g / cm ³ or less,
ii) barium sulfate content of more not more than 0.3 mass% 0.5 mass% or less, and the density is 3.7 g / cm ³ or more 4.0 g / cm ³ or less

Preferably, the negative electrode material has a carbon content of 0.2% mass% or less, such as 0.2 mass% or less and 0.1 mass% or more. In Patent Document 1, the capacity is maintained by containing a high concentration of carbon. In this invention, the density of the negative electrode material is 3.6 / cm ³ or more, and the barium sulfate content is less than 0.6 mass% and more than 0. Thus, the capacity can be maintained. And no more than 0.2mass% carbon is needed.

  The lead acid battery of the present invention can be used in applications including a discharge process in which the utilization factor of the negative electrode material is 30% or more, and can be used particularly in applications in which the average utilization factor of the negative electrode material per cycle is 30% or more. . Preferably, it can be used in applications including a discharge process in which the utilization factor of the negative electrode material is 40% or more, and in particular, can be used in applications in which the average utilization factor of the negative electrode material per cycle is 30% or more.

  Further, when the theoretical capacity of the positive electrode material is, for example, 86% or more of the theoretical capacity of the negative electrode, deterioration of the positive electrode such as softening can be suppressed.

Characteristic diagram showing the cycle test results when the negative electrode material density is 3.8 g / cm ³ and the barium sulfate concentration is 0.1 to 0.8 mass% Negative electrode material density 3.6 g / cm ³ and 3.7 g / cm ^3, characteristic diagram showing barium sulfate concentration is in 0.2~0.6mass%, the cycle test results Negative electrode material density 3.9 g / cm ³ and 4.0 g / cm ^3, characteristic diagram showing barium sulfate concentration is in 0.3~0.8mass%, the cycle test results Characteristic diagram showing the relationship between the barium sulfate content and the ratio of the discharge capacity to the theoretical capacity of the negative electrode material at the 1400th cycle of discharge with a utilization rate of 44% Characteristic chart showing the relationship between the barium sulfate content and the ratio of the discharge capacity to the theoretical capacity of the negative electrode material at the 1400th cycle of discharge with a utilization rate of 20%

  Hereinafter, an optimum embodiment of the present invention will be described. In carrying out the present invention, the embodiments can be appropriately changed in accordance with common sense of those skilled in the art and disclosure of prior art. In Examples, the negative electrode material may be referred to as a negative electrode active material, and the positive electrode material may be referred to as a positive electrode active material. The negative electrode plate includes a negative electrode current collector such as a negative electrode grid and a negative electrode material (negative electrode active material), and the positive electrode plate includes a positive electrode current collector such as a core metal and a positive electrode material (positive electrode active material). The solid components other than the current collector belong to the electrode material. In this specification, when a range is indicated by “to”, an upper limit and a lower limit are included.

Five paste-type negative electrode plates with a height of 300 mm, a width of 140 mm, and a thickness of 3.5 mm, and four tube-type positive electrode plates with the same outer dimensions and a tube diameter of 10 mm are passed through a polyethylene microporous separator after tank formation. Laminated and used as a lead storage battery for forklifts. The density of the negative electrode material of the negative electrode plate and ^{3.6g / cm 3 ~4.0g / cm 3} , relative to the negative electrode material, 0.2 mass% of acetylene black as carbon, lignin sulfonate 0.2 mass%, the barium sulfate 0.1 A negative electrode plate containing ˜0.8 mass% was prepared. Acetylene black may be replaced with other carbon black, and the type of carbon is arbitrary. In addition, whether the sulfonic acid group of lignin sulfonic acid was H-type bonded with H ⁺ or Na-type bonded with Na ⁺ did not give a significant difference in the results. Instead of lignin sulfonic acid, a sulfonated bisphenol condensate or the like may be used. Barium sulfate having a peak particle size of 1.20 μm and a volume average particle size of 1.40 μm was used, but properties such as particle size are arbitrary.

The positive electrode active material was composed mainly of lead dioxide, the theoretical capacity for four positive plates was 710 ± 5 Ah, and the theoretical capacity for five negative plates was 575 ± 3 Ah. Attach an envelope-like separator to the negative electrode so as to surround the three sides except the upper side, put the electrode group in the battery case, and inject 2800 cm ³ (theoretical capacity about 357 Ah) of dilute sulfuric acid with a specific gravity of 1.28 (20 ° C), Three prototype cells were manufactured for each type of negative electrode plate.

  The theoretical capacity of the positive electrode material is preferably 86% or more of the theoretical capacity of the negative electrode. By doing in this way, the performance fall of the positive electrode plate accompanying a charging / discharging cycle can be suppressed. Since this effect is further improved, the theoretical capacity of the positive electrode material is preferably 114% or more, more preferably 125% or more of the theoretical capacity of the negative electrode. By suppressing the performance degradation of the positive electrode plate accompanying the charge / discharge cycle, the ratio that the life performance of the negative electrode plate affects the life performance of the entire battery increases, and thus the significance of the present invention increases.

The type of negative electrode active material is represented by a symbol such as “3D2”, the leading “3” indicates that 0.3 mass% of barium sulfate is contained, and “D” indicates that the density of the preformed negative electrode active material is 3.8 g / cm ³ "2" at the end indicates that the data is shown as an average of two cells. Density of the negative electrode active material noted previously Kasei, B is 3.6g / cm ^3, C is 3.7g / cm ^3, E is 3.9g / cm ^3, F is 4.0 g / cm ^3. For example, in 5C2, the preformed negative electrode active material contains 0.5 mass% of barium sulfate and the density is 3.7 g / cm ³ .

  When the prototype battery was discharged at 45 A in a 30 ° C. water bath and the amount of discharged electricity when the terminal voltage fell below 1.7 V was measured, it was about 252 Ah regardless of the type of the negative electrode plate. Therefore, the standard capacity of the battery was set to 252 Ah (44% in terms of the utilization ratio (negative electrode utilization ratio) with respect to the theoretical capacity of the negative electrode). The prototype battery was put into the following cycle life test. That is, in a 30 ° C water bath, discharging is performed at a current of 67A for 3 hours (negative electrode utilization rate 35%), charging is repeated at a current of 48A for 5 hours, and discharging and charging are repeated, and every 100 cycles at 30 ° C, 45A, A discharge capacity test with a final voltage of 1.7 V was performed. During the cycle life test, one cell of each battery was disassembled immediately before the discharge capacity test at the 100th cycle, and the BET specific surface area was measured. The BET specific surface area increased with the barium sulfate content, confirming that barium sulfate prevented shrinkage of the negative electrode active material. In the battery, the theoretical capacity of the electrolyte is about 62% of the theoretical capacity of the negative electrode material. With this configuration, deep discharge exceeding a negative electrode utilization rate of 30% can be achieved.

  The remaining two cells were put into a cycle life test up to 1400 cycles, and after 1400 cycles, the content of lead sulfate in the negative electrode active material was measured. Contrary to expectation, the content of lead sulfate increases with the content of barium sulfate, which indicates that barium sulfate accumulates lead sulfate with repeated deep discharges. Moreover, the behavior of capacity up to 400 cycles and the behavior of capacity after 1000 cycles were different, and even in batteries with stable capacity up to 400 cycles, a phenomenon was observed in which the capacity decreased rapidly from around 1000 cycles. These facts suggest that barium sulfate suppresses the decrease in BET specific surface area and maintains the capacity at the 100th cycle, but the lead sulfate accumulation proceeds by barium sulfate at the 1400th cycle and the capacity decreases. .

Density of the negative electrode active material results in the D series of 3.8 g / cm ³ in FIG. 1, the results of the C series of B-series and 3.7 g / cm ³ of 3.6 g / cm ³ in FIG. 2, 3.9 g / The results for the cm ³ E series and 4.0 g / cm ³ F series are shown in FIG.

In the D series of FIG. 1, when the barium sulfate content is 0.1 mass%, the capacity decrease at the 100th cycle is remarkable, when 0.8 mass%, the capacity decrease after the 300th cycle is remarkable, and at 0.6 mass%, the capacity decreases after the 600th cycle. Was authoritative. When the barium sulfate content is 0.15 mass%, the capacity is low but stable, suggesting that it is important to lower the barium sulfate content for durability against repeated deep discharge. A high capacity was obtained at the 1400th cycle when the barium sulfate content was 0.15 mass% to 0.5 mass%, and this range was optimal when the density was 3.8 g / cm ³ .

In the B series (density 3.6 g / cm ³ ) among the B series and C series in FIG. 2, the capacity at the 1400th cycle was low regardless of the barium sulfate content. This indicates that when the density of the negative electrode active material is low, durability against repeated deep discharge cannot be obtained. In the C series (density 3.7 g / cm ³ ), the barium sulfate content was 0.3 mass% (3C2) and 0.5 mass% (5C2), and the capacity at the 1400th cycle was high.

In the E series (density 3.9 g / cm ³ ) and F series (density 4.0 g / cm ³ ) in Fig. 3, if the barium sulfate content is 0.6 mass% or more, the 1400th cycle is achieved regardless of the barium sulfate content. The capacity was low. In contrast, the density of the negative electrode active material was 3.9 g / cm ³ , the barium sulfate content was 0.3 mass%, and the capacity at the 1400th cycle was high. As described above, the fact that the barium sulfate content is preferably less than 0.6 mass% is common to all densities.

Of the above evaluation results, those and 3.6 g / cm ³ boiled for density of the negative electrode active material 3.8 g / cm ^3, respectively the relationship between the discharge capacity and the content of the barium sulfate 1400 cycle in FIG. 4 . As a comparison, FIG. 5 shows the result of separately evaluating the tendency when the discharge depth is shallower. The results in FIG. 5 were obtained by changing the discharge conditions in the above test to 20% of the theoretical capacity of the negative electrode material (that is, the negative electrode utilization rate of 20%). The discharge capacity at the 1400th cycle was evaluated as a ratio to the theoretical capacity of the negative electrode material.

  From FIG. 4, when discharge was performed such that the density of the negative electrode active material was 3.8 g / cm3 and the negative electrode utilization rate was 44%, the content was reduced in the range of barium sulfate content of 0.4 mass% to 0.8 mass%. Therefore, it can be seen that the discharge capacity at the 1400th cycle is greatly improved. On the other hand, FIG. 4 and FIG. 5 show that such a tendency is not observed when the negative electrode density is 3.6 g / cm 3 or when the negative electrode utilization rate is 20%. These are the reasons why the barium sulfate content is reduced when an electrolyte solution capable of discharging a capacity corresponding to 44% of the theoretical capacity of the negative electrode material is provided and the density of the negative electrode material is 3.8 g / cm3. This means that the effect of improving the life performance can be remarkably obtained by the reduction.

  The above phenomenon is presumed to be related to the degree of influence of barium sulfate on the conductivity of the negative electrode material. In other words, since barium sulfate has low conductivity, when added to the negative electrode material, the conductivity of the negative electrode material decreases. Under certain conditions, this decrease is presumed to cause the accumulation of lead sulfate. The At a shallow discharge depth where the negative electrode utilization rate is about 20%, the discharge state is almost uniform throughout the negative electrode plate, and the conductivity of the negative electrode material is high even during charging, so the amount of barium sulfate added is 0.6 mass. If it is about%, the inside of the negative electrode material can maintain sufficient conductivity. This is also clear from the fact that the content of barium sulfate in the prior art is 1.4 to 2.25 mass%. Therefore, in the conventional lead acid battery, the phenomenon that about 0.6 mass% barium sulfate accelerates the accumulation of lead sulfate does not occur. On the other hand, when the negative electrode utilization is discharged to a deep discharge depth such as 44% as in the above test, the non-uniformity of the discharge state in the negative electrode plate becomes remarkable, for example, locally exceeding 50%. In particular, a portion having a deep discharge depth occurs. In such a place, the conductivity of the negative electrode material at the time of charging is particularly low, making it difficult to accept charging. Under such circumstances, the effect of the decrease in conductivity due to the addition of barium sulfate is large, and it is estimated that the conductivity was lowered to the extent that the accumulation of lead sulfate was accelerated.

  Considering based on such a mechanism, the effect of improving the lifetime performance by reducing the content of barium sulfate is when performing a charge / discharge cycle including a discharge in which the utilization factor of the negative electrode material is 30% or more, In particular, it can be observed clearly. Further, it is considered that the phenomenon is more remarkably observed when the discharge is performed such that the utilization factor of the negative electrode material becomes 40% or more. When a charge / discharge cycle that includes a discharge in which the utilization factor of the negative electrode material is 30% or more is performed, accumulation of lead sulfate is clearly recognized, and a discharge in which the utilization factor of the negative electrode material is 40% or more The accumulation of lead sulfate becomes even more pronounced. And the situation that accumulation of lead sulfate has occurred means that the conductivity of the active material is reduced in the charging process. For this reason, even if the addition amount is about 0.6 mass%, in particular, in the state where the non-uniformity of the discharge state is remarkable in the negative electrode plate, particularly the deep discharge depth, It is considered that barium sulfate has a great influence on the conductivity of the existing portion. In such a situation, it is estimated that accumulation of lead sulfate can be significantly avoided or suppressed by reducing the amount of barium sulfate. Therefore, this effect is easily exhibited in a battery in which the theoretical capacity of the electrolytic solution is 30% or more of the theoretical capacity of the negative electrode material, and is more prominent when it is 40% or more.

  The effect of improving the life performance by reducing the content of barium sulfate is not clear for reasons, but is recognized only when the density of the negative electrode material is larger than 3.6 g / cm 3. As shown in FIG. 4, this effect cannot be obtained when the density is 3.6 g / cm 3. On the other hand, it was confirmed that the same tendency was observed when the density of the negative electrode material was 3.7 g / cm 3, 3.9 g / cm 3 and 4.0 g / cm 3. From these facts, it is estimated that this effect can be obtained in a density range higher than 3.6 g / cm 3.

  From the above, in the present invention, the effect of improving the life performance obtained by reducing the barium sulfate content is that the theoretical capacity of the electrolyte is 30% or more of the theoretical capacity of the negative electrode material, and the negative electrode material It can be said that this is a phenomenon that is uniquely confirmed in a lead storage battery having a density higher than 3.6 g / cm 3. The present invention is significant in applications where the utilization ratio of the negative electrode material is 30% or more, and is further significant in applications where the ratio is 40% or more.

These results are contrary to the guidelines of Patent Document 2 in which the content of barium sulfate in the negative electrode active material is increased in applications involving deep discharge such as for forklifts. In addition, the combination of the barium sulfate content and the density of the negative electrode active material is important. It is important that the density of the active material is higher than 3.6 g / cm ³ and the barium sulfate content is less than 0.6 mass%. It is shown that.

The discharge capacity at the 1400th cycle relative to the theoretical capacity of the negative electrode is summarized in Table 1, and the gray area is the optimum area. Barium content sulfate may have less than 0.6 mass% with 0.1mass% greater, especially more than 0.15 mass% 0.5 mass% or less, the density of the negative electrode active material 3.8 g / cm ³ or more 4.0 g / cm ³ or less is optimal, density barium sulfate content is superior range of not more than 0.3 mass% or more 0.5 mass% at 3.7 g / cm ³ or more 3.8 g / cm ³ or less. Generalizing these things, below is 0.1mass% Ultra 0.6 mass% barium sulfate content, preferably the density is 3.7 g / cm ³ Ultra 4.0 g / cm ³ or less of the region, barium sulfate content among this is A region of more than 0.15 mass% and less than 0.6 mass% is preferable. The density is less than 0.2 mass% Ultra 0.6 mass% barium sulfate content is preferably also 3.6 g / cm ³ Ultra 4.0 g / cm ³ or less regions.

Although it has been recognized that the life performance improved by the addition of barium sulfate is roughly proportional to the amount added, the above-mentioned preferred range shows a performance improvement exceeding the proportional relationship inside and outside the range. That is, it can be seen from Table 1 that, for example, when the negative electrode density is 3.8 g / cm 3, the discharge capacity is improved from 25% to 31% when the barium sulfate content is changed from 0.1% to 0.15%. As a comparison, it can be seen that when the negative electrode density is 3.6 g / cm 3, the discharge capacity generally tends to increase by 1% as the barium sulfate content increases by 0.1%. This trend can also be seen in FIG. These contrasting, or 0.15 mass% 0.5 mass% or less, to obtain the density of the negative electrode active material by a 3.8 g / cm ³ or more 4.0 g / cm ³ or less in the range, a remarkable effect as compared with the range You can see that The same reason a density of 3.7 g / cm ³ or more that 3.8 g / cm ³ range barium sulfate content less not more than 0.3 mass% or more 0.5 mass% or less even remarkable effect is obtained can be seen.

  The above cycle test is equivalent to driving a forklift with a negative electrode utilization rate of 35% in the daytime, charging at night, and omitting even charging on weekends. Under this condition, the capacity against the theoretical capacity can be maintained at 30% or more for 1400 cycles, and it was assumed that the operating conditions were severe so that the negative electrode utilization rate exceeded 40%, and this was compensated by even charging over the weekend. This suggests that lead-acid batteries for forklifts can be used for 5 years under conditions where the negative electrode utilization rate exceeds 40%.

  In addition to the lead storage battery for forklifts, the present invention is preferably used for applications that undergo a discharge process with a negative electrode utilization rate of 30% or more. Moreover, according to the present invention, a lead storage battery in which 30% or more or 40% or more of the theoretical capacity of the negative electrode active material is determined as the rated capacity can be supplied to the market. Such a lead storage battery suppresses a decrease in capacity when it is repeatedly charged and discharged and used even if the user uses 100% of the rated capacity without additional charging.

  The quantification method of various materials in this invention is shown. The lead-acid battery after full charge is disassembled, the negative electrode plate is washed with water and dried to remove sulfuric acid, and the negative electrode material is collected. The negative electrode material was pulverized, 20 mL of 300 g / L hydrogen peroxide was added per 100 g of negative electrode material, and 60 mass% concentrated nitric acid was diluted with 3 times its volume of ion-exchanged water (1 + 3) nitric acid And heat for 5 hours under stirring to dissolve lead as lead nitrate. The carbon black, barium sulfate, and reinforcing material (if included) are then separated by filtration.

The solid obtained by filtration is dispersed in water. A sieve that does not allow the reinforcement to pass through
Using a 1.4mm sieve, the dispersion is passed through the sieve twice and washed with water to remove the reinforcing material. Next, for example, centrifugation is performed at 3000 rpm × 5 minutes, and carbon black is extracted from the supernatant and the upper precipitate, and barium sulfate is extracted from the lower precipitate. The barium sulfate and carbon black separated by the above series of operations are washed with water and dried, and then the respective weights are weighed.

  The method for measuring the density of the negative electrode material in the present invention is described below. The anode electrode material that is already formed and fully charged is washed with water and vacuum dried, separated from the grid, pretreated so as not to form mercury amalgam, and then filled into a container for mercury intrusion test. The mass is measured, and then the volume of the negative electrode material when mercury is injected so that the pores of 100 μm or more are filled with mercury is measured. The density of the negative electrode material is calculated by dividing the mass of the negative electrode material by this volume.

Claims (5)

The theoretical capacity of the electrolyte is 30% or more of the theoretical capacity of the negative electrode material, the negative electrode material contains barium sulfate greater than 0 and less than 0.6 mass%, and the density of the negative electrode material is 3.6 g / cm ³ Lead acid battery characterized by being higher. 2. The lead acid battery according to claim 1, wherein the negative electrode material has a content and density of the barium sulfate satisfying any one of the following ranges.
i) Barium sulfate content is greater than 0.1 mass% and density is greater than 3.7 g / cm ³ ,
ii) Barium sulfate content is greater than 0.2 mass% and density is higher than 3.6 g / cm ³ The lead acid battery according to claim 2, wherein the negative electrode material has a content and density of the barium sulfate satisfying any one of the following ranges.
i) barium sulfate content of less 0.15 mass% or more 0.5 mass%, and density of 3.8 g / cm ³ or more 4.0 g / cm ³ or less,
ii) barium sulfate content of more not more than 0.3 mass% 0.5 mass% or less, and the density is 3.7 g / cm ³ or more 4.0 g / cm ³ or less   The lead-acid battery according to any one of claims 1 to 3, wherein the negative electrode material has a carbon content of 0.2% mass% or less.   The lead-acid battery according to any one of claims 1 to 4, wherein the lead-acid battery is used in an application including a discharge process in which a utilization factor of the negative electrode material is 30% or more.