JP2017079144A - Lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead storage battery capable of maintaining a high positive electrode utilization rate even if charge/discharge is repeated.SOLUTION: A positive electrode material contains Sb of 0.05 mass% or more and carbon of 0.05 mass% or more. Carbon contains at least one of graphite, expanded graphite, activated carbon and coke. The density of the positive electrode material is 3.45 g/cm3 or less and the positive electrode is a clad type.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lead storage battery.

  In the patent document 1 (JP2010-277799), the applicant applies 0.005 mass% to 0.5 mass% Sb and 0.05 mass% to 0.5 mass% glass short fiber as the electrode material of the paste-type positive electrode plate. Proposed to contain. As a result, the charge / discharge cycle life is remarkably increased as compared with the case of containing Sb and short glass fibers individually.

  Patent Document 2 (JP2008-243480) states that the electrode material of the paste-type positive electrode plate contains Bi of 0.01 mass% to 0.5 mass% and expanded graphite of 0.1 mass% to 2.0 mass%. is suggesting. According to Patent Document 2, softening of the positive electrode material is suppressed by Bi, expanded graphite disappears when oxidized in the positive electrode material, and the remaining holes improve the positive electrode utilization rate.

JP2010-277799 JP2008-243480

  The subject of this invention is providing the lead acid battery which can maintain a high positive electrode utilization factor even if charging / discharging is repeated.

The lead acid battery of this invention is characterized in that the positive electrode material contains Sb and carbon.
The Sb content is preferably 0.05 mass% or more in terms of metal. The positive electrode material preferably contains 0.05 mass% or more of carbon.

  The positive electrode for a lead storage battery according to the present invention is characterized in that the positive electrode material contains Sb and carbon. The Sb content is, for example, 0.05 mass% or more in terms of metal. Carbon is preferably contained, for example, in an amount of 0.05 mass% or more in the positive electrode material. In addition, in this specification, the description regarding the positive electrode in a lead acid battery is applicable also to the positive electrode itself for lead acid batteries before incorporating in a lead acid battery. Moreover, the description regarding the positive electrode for lead acid batteries is applicable also to lead acid batteries themselves.

  When Sb and carbon are contained in the positive electrode material of the positive electrode of the lead storage battery, a high positive electrode utilization rate can be maintained even if charge and discharge are repeated. Moreover, this effect is larger than the sum of the effect when only Sb is contained and the effect when only carbon is contained. In addition, Sb content is converted into Sb metal and shown as a ratio to the positive electrode material. To show the ratio in terms of metal means to show the content of the element, not the amount of the compound.

  The effect of Sb is manifested by the presence, and at 0.5 mass%, the positive electrode utilization rate is conversely reduced, so the upper limit is preferably set to 0.3 mass%. For this reason, it is preferable that positive electrode material contains 0.3 mass% or less Sb in metal conversion. Moreover, since an effect appears largely at 0.05 mass%, it is preferable to contain 0.05 mass% or more.

  Further, the effect of carbon is manifested by the presence, and at 1.3 mass%, on the contrary, the positive electrode utilization factor decreases, so the upper limit is preferably set to 1.0 mass%. In addition, since the effect appears at 0.05 mass%, the positive electrode material preferably contains 0.05 mass% or more of carbon.

  Particularly preferably, the positive electrode material contains 0.05 mass% to 0.3 mass% Sb and 0.05 mass% to 1.0 mass% carbon in terms of metal. When this condition is satisfied, the maintenance factor of the positive electrode utilization rate when charging / discharging is repeated can be made particularly high.

  The type of carbon is arbitrary and is, for example, graphite, activated carbon, coke, etc., preferably graphite, and most preferably unexpanded graphite. The effect of maintaining the positive electrode utilization rate is the largest for unexpanded graphite, followed by expanded graphite, and the effect of low electrical conductivity such as activated carbon is smaller than that of graphite.

The effect of the present invention is increased with a low-density positive electrode material. According to experiments, when the density is 3.55 g / cm ³ , the effect of Sb and carbon is small, so the density of the positive electrode material is 3.45 g / cm ³ or less. preferable. Note the density could produce a practical lead-acid battery without any particular problem to 3.16 g / cm ^3, and more preferably the density of the positive electrode material is not more than 3.16 g / cm ³ or more 3.45 g / cm ^3.

  If said positive electrode is made into a clad type instead of a paste type, the positive electrode utilization factor at the time of repeating a charging / discharging cycle can be maintained higher. For this reason, it is preferable that said positive electrode is a clad type.

  It is considered that Sb suppresses softening of the positive electrode material, and carbon having a lower density than the electrode material uniformly lowers the density of the positive electrode material and improves the positive electrode utilization rate due to its conductivity.

  Furthermore, in the clad positive electrode, it is considered that the carbon expands in the positive electrode material, so that the positive electrode material is pressed against the glass fiber tube and the structure is maintained, and the carbon disappears due to oxidation. It is considered that the electrolyte is held in the pores and contributes to the positive electrode utilization rate.

  However, these are the effects of Sb and carbon alone, and the mechanism for the synergistic effect of Sb and carbon is unknown. Hereinafter, embodiments of the present invention will be exemplified.

Form 1:
A lead-acid battery, wherein the positive electrode material contains Sb and carbon.

Form 2:
The lead-acid battery according to aspect 1, wherein the Sb is 0.05 mass% or more in terms of metal.

Form 3:
The lead-acid battery according to aspect 1, wherein the carbon is 0.05 mass% or more in terms of metal.

Form 4:
The lead-acid battery according to Form 1 or 2, wherein the positive electrode material contains 0.3 mass% or less of Sb in terms of metal.

Form 5:
The lead-acid battery according to aspect 1 or 3, wherein the positive electrode material contains 1.0 mass% or less of carbon.

Form 6:
It is a lead acid battery in any one of form 1-5, Comprising: Positive electrode material contains Sb of 0.05 mass% or more and carbon of 0.05 mass% or more in metal conversion, It is characterized by the above-mentioned.
Form 7:

  It is a lead acid battery in any one of form 1-6, Comprising: Positive electrode material contains Sb of 0.3 mass% or less and carbon of 1.0 mass% or less in conversion of a metal, It is characterized by the above-mentioned.

Form 8:
It is a lead acid battery in any one of form 1-7, Comprising: The said carbon contains at least 1 sort (s) among graphite, expanded graphite, activated carbon, and coke, It is characterized by the above-mentioned.

Form 9:
It is a lead acid battery in any one of form 1-8, Comprising: The density of the said positive electrode material is 3.45 g / cm < ³ > or less.

Form 10:
It is a lead acid battery in any one of form 1-9, Comprising: The density of the said positive electrode material is 3.16 g / cm < ³ > or more.

Form 11:
It is a lead acid battery in any one of form 1-10, Comprising: A positive electrode is a clad type, It is characterized by the above-mentioned.

Form 12:
A positive electrode for a lead storage battery, wherein the positive electrode material contains Sb and carbon.

Form 13:
The positive electrode for a lead storage battery according to the twelfth aspect, wherein the Sb is 0.05 mass% or more in terms of metal.

Form 14:
The positive electrode for a lead storage battery according to the twelfth aspect, wherein the carbon is 0.05 mass% or more in terms of metal.

Form 15:
It is a lead acid battery in any one of form 12-14, Comprising: Positive electrode material contains 0.3 mass% or less Sb in metal conversion, It is characterized by the above-mentioned.

Form 16:
16. The lead-acid battery according to any one of Forms 12 to 15, wherein the positive electrode material contains 1.0 mass% or less of carbon.

Form 17:
The lead-acid battery according to Form 10, wherein the positive electrode material contains 0.05 mass% or more of Sb and 0.05 mass% or more of carbon in terms of metal.

Form 18:
It is a lead acid battery in any one of form 12-17, Comprising: It is a lead acid battery of form 1, Comprising: Positive electrode material contains Sb of 0.3 mass% or less in conversion of metal, and carbon of 1.0 mass% or less It is characterized by doing.

Form 19:
It is a lead acid battery in any one of form 12-18, Comprising: The positive electrode for said carbon contains at least 1 sort (s) among graphite, expanded graphite, activated carbon, and coke, It is characterized by the above-mentioned.

Form 20:
20. The lead-acid battery according to any one of forms 12 to 19, wherein the positive electrode material has a density of 3.45 g / cm ³ or less.

Form 21:
21. The lead acid battery according to any one of Forms 12 to 20, wherein the positive electrode material has a density of 3.16 g / cm ³ or more.

Form 22:
The positive electrode for a lead storage battery according to any one of Forms 12 to 21, wherein the positive electrode is a clad type.

The specific gravity of the electrolytic solution is 1.320, the density of the positive electrode active material is 3.41 g / cm ^3, and after 100 cycles, the relationship between the positive electrode utilization rate and the carbon content in a 30 ° C. water bath is as follows. Characteristic diagram for 0.2 mass% Fig. 1 is a characteristic diagram showing the data in Fig. 1 as relative values when the carbon content and Sb content are both 0. The specific gravity of the electrolytic solution is 1.320, the density of the positive electrode active material is 3.41 g / cm ^3, and after 100 cycles, the relationship between the positive electrode utilization rate and the Sb content in a 30 ° C. water bath, the carbon content is 0 mass% and Characteristic diagram for the case of 0.3 mass% Characteristic diagram showing the data in Fig. 3 as relative values when the carbon content and Sb content are both 0. The specific gravity of the electrolyte is 1.320, the density of the positive electrode active material is 3.41 g / cm ³ , and the relationship between the initial value of the positive electrode utilization rate and the carbon content in a water bath at 30 ° C., the Sb content is 0 mass% and 0.2 Characteristic diagram for mass% Fig. 5 is a characteristic diagram showing the relative values with 100% when the carbon content and Sb content are 0. The specific gravity of the electrolyte is 1.320, the density of the positive electrode active material is 3.41 g / cm ³ , and the relationship between the initial value of the positive electrode utilization rate and the Sb content in a water bath at 30 ° C., the carbon content is 0 mass% and 0.3%. Characteristic diagram for mass% Fig. 7 is a characteristic diagram showing the data in Fig. 7 as relative values when the carbon content and Sb content are both 0. The specific gravity of the electrolytic solution is set to 1.320, and after 100 cycles, the relationship between the positive electrode utilization rate and the positive electrode active material density in a 30 ° C. water bath is as follows. , Characteristic diagram shown for additive-free products containing neither carbon nor Sb The specific gravity of the electrolyte is 1.320, the density of the positive electrode active material is 3.41 g / cm ^3, and the utilization rate of the positive electrode in a water bath at 30 ° C. after 100 cycles is 100% for the additive-free product containing neither carbon nor Sb. Relative value, characteristic diagram for clad and paste types

  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. When the positive electrode plate is a clad type, the positive electrode plate (positive electrode) is composed of a positive electrode current collector (core metal, positive electrode lattice, etc.), a positive electrode material (positive electrode active material), a glass fiber tube, upper and lower frames, etc. Solid components other than the cored bar in the glass fiber tube belong to the positive electrode material, and the negative electrode plate (negative electrode) is composed of a negative electrode current collector (negative electrode lattice, etc.) and a negative electrode material (negative electrode active material). To do. When the positive electrode is a paste type, the negative electrode plate (negative electrode) is composed of a negative electrode current collector (negative electrode lattice, etc.) and a negative electrode material (negative electrode active material), and the positive electrode plate (positive electrode) is a positive electrode current collector (positive electrode). Lattice) and a positive electrode material (positive electrode active material).

Manufacture of lead-acid batteries A mixed powder of lead powder and Sb ₂ O ₃ powder as an Sb source was filled into a clad electrode plate in which glass fiber tubes having Pb—Ca—Sn-based metal cores were arranged. And the density of the positive electrode active material after chemical conversion was changed by changing filling conditions. The content was changed so that the Sb content after chemical conversion was in the range of 0 (more precisely, 0.005 mass% or less) to 0.5 mass%. After filling the active material, it was immersed in dilute sulfuric acid and then dried in the air to obtain an unchemically formed positive electrode. Hereinafter, a composition is shown by the composition after chemical conversion.

The type and production conditions of lead powder are arbitrary, the presence or absence and content of synthetic fiber reinforcement etc. are arbitrary, the Sb source may be metal Sb, SbOOH, Sb ₂ O ₅ etc., and Pb-Sb alloy is a lead powder material As an alternative, the Sb element may be supplied from lead powder. As for carbon, ordinary graphite not subjected to sulfuric acid treatment for preparing expansion, expanded graphite, activated carbon, coke, and carbon black were examined. Since activated carbon and coke were equivalent, the data for activated carbon is shown. Further, since carbon black easily flows out of the positive electrode plate and makes the electrolyte solution turbid, carbon other than this is preferable. Hereinafter, when simply referred to as carbon or graphite, it refers to normal carbon or graphite not subjected to sulfuric acid treatment or the like. The average particle diameter of ordinary graphite used was 180 μm, but a preferred range is 10 μm or more and 500 μm or less.

  Lead powder, organic shrinkage agent, barium sulfate, carbon black, and synthetic fiber reinforcement were kneaded with water and sulfuric acid to obtain a negative electrode active material paste. Sulfonated lignin was added to the negative electrode active material after conversion (strictly, the negative electrode material) as an organic anti-shrink agent so as to be 0.10 mass%. Barium sulfate was contained at 1.0 mass%, synthetic fiber reinforcing material at 0.05 mass%, and carbon black at 0.2 mass% (relative to the negative electrode active material after conversion (strictly, the negative electrode material)). The preferred content range of these components is 0.05 mass% or more and 0.3 mass% or less for organic shrinkage agent, 0.5 mass% or more and 2.0 mass% or less for barium sulfate, and 0.03 mass% or more and 0.2 mass% or less for synthetic fiber reinforcement. Carbon such as carbon black is 3.0 mass% or less. The negative electrode active material may contain components other than those described above. The negative electrode active material paste was filled in a cast lattice made of a Pb—Ca—Sn alloy, dried and aged to obtain an unformed negative electrode plate.

The unformed negative electrode plate is wrapped in a microporous polyethylene separator and set in a battery case together with a clad positive electrode, and an electrolytic solution consisting of sulfuric acid (adjusted to a specific gravity of 1.32 at 20 ° C after formation) is added to form a battery case. In addition, a clad lead-acid battery having a 2V output and a 5-hour rate capacity (C ₅ , hereinafter referred to as C) of 165 Ah was obtained.

Measurement of Positive Electrode Utilization Rate The positive electrode utilization rate is 0.2CA discharge capacity (Ah) ÷ positive electrode theoretical capacity (Ah), and is expressed in%. Note the positive electrode theoretical capacity, Sadamari with PbO ₂ weight in the positive electrode active material (g) ÷ 4.463 (g / Ah), PbO 2 weight is obtained by converting the amount of Pb in the positive electrode active material PbO ₂ amount. In the case of a new storage battery, charge and discharge for 10 cycles under the following conditions after the initial charge.
Discharge: 0.2CA, final voltage per cell is 1.70V
Charging: 0.2 CA, 135% of discharged electricity

  In the case of a new storage battery, the battery was fully charged after 10 cycles, the liquid level of the electrolyte was adjusted, and left overnight. Next, the capacity was measured in a 30 ° C. water bath with a final voltage of 1.70 V at 0.2 CA, and the initial value of the positive electrode utilization rate was measured. After measuring the initial value, the lead-acid battery was discharged in a water bath at 10 ° C. at 0.22 CA for 3 hours and charged at 115% of the amount of discharged electricity at 0.18 CA for 100 cycles. After 100 cycles, as a vibration test, perform a test that vibrates in the vertical direction at an acceleration of 1.5 ± 0.1G for 0.5 hours, and then perform the full charge by omitting the above 10 cycles of charge / discharge. Similarly, the capacity was measured, and the positive electrode utilization rate after 100 cycles was measured.

Test results Tables 1 to 11 show the test results, and main data are shown again in FIGS. Tables 1 and 2 show the positive electrode utilization rate after 100 cycles of the above cycle including a discharge of 0.22 CA × 3 hours, Table 1 shows the utilization rate itself, and Table 2 shows the relative value of the utilization rate. . The results when the Sb content is fixed at 0 mass% and 0.2 mass% and the carbon content is changed are shown in Fig. 1 (utilization rate itself) and Fig. 2 (relative value of the utilization rate), and the carbon content is 0 mass%. Fig. 3 (utilization rate itself) and Fig. 4 (relative value of the utilization rate) show the results when the Sb content is changed while fixing at 0.3 mass%.

  As is apparent from FIGS. 1 and 2, when 0.2 mass% Sb is contained, the effect of carbon appears more strongly. 3 and 4, when 0.3 mass% of carbon is contained, the effect of Sb appears more strongly. These facts indicate that Sb and carbon have a synergistic effect and have improved the positive electrode utilization rate after repeated charge and discharge.

  When Sb is contained, the effect of carbon is manifested by the presence of carbon, and becomes noticeable at 0.05 mass% and becomes clearer at 0.1 mass%, so the lower limit of the carbon content is 0.05 mass%, more preferably 0.1 mass%. The effect of carbon reaches the upper limit at 0.6 mass% to 1.0 mass%, and the positive electrode utilization starts to decrease at 1.3 mass%, so the upper limit of the more preferable range was set to 1.0 mass%.

  In the case of containing carbon, the effect of Sb is manifested by the presence, and the effect appears greatly at 0.05 mass%, so the lower limit of the Sb content is 0.05 mass%. The effect is maximum at 0.2 mass%, and the positive electrode utilization rate decreases at 0.5 mass%, so the upper limit was set to 0.3 mass%.

  Table 3 shows the initial value of the utilization rate, and Table 4 shows the relative value of the initial value of the utilization rate. 5 and 6 show the results when the Sb content is fixed at 0 mass% and 0.2 mass% and the carbon content is changed. FIG. 5 shows the initial value of the utilization rate, and FIG. 6 shows the initial value of the utilization rate. Indicates the relative value of. 7 and 8 show the results when the carbon content is fixed at 0 mass% and 0.3 mass% and the Sb content is changed. FIG. 7 shows the initial value of the utilization rate, and FIG. 8 shows the initial value of the utilization rate. Indicates the relative value of.

  Table 5 shows the effect of each type of carbon on the positive electrode utilization rate after experiencing 100 cycles of the above cycle. The Sb content was 0.2 mass% and the carbon content was 0.3 mass%. Graphite gave better results than activated charcoal, and among graphite, unexpanded normal graphite was found to be preferred over expanded graphite. Furthermore, it was found that even when a plurality of various carbons were contained, a combination containing unexpanded ordinary graphite was more preferable.

Table 6 and FIG. 9 show the effect of the density of the positive electrode material on the positive electrode utilization after 100 cycles of the above cycle. And a result is shown with respect to the Example which contains 0.2 mass% of Sb, and 0.3 mass% of carbon, and the comparative example which does not contain Sb and carbon. By containing Sb and carbon, a high utilization factor was obtained even when the active material density was low, and the difference in utilization factor increased as the active material density was low. Density particularly good utilization is obtained at 3.29 g / cm ³ and 3.41 g / cm ^3, utilization comparable to the comparative example of the density of 3.55 g / cm ^3, even density 3.16 g / cm ³ was obtained. Accordingly, the density of the positive electrode active material is preferably 3.45 g / cm ³ or less, and particularly preferably 3.16 g / cm ³ or more and 3.45 g / cm ³ or less.

  Conventionally, attempts have been made to lower the positive electrode active material density in order to improve the utilization rate of the positive electrode active material. However, although the utilization rate improved initially, the utilization rate decreased after about 100 cycles, and a continuous effect could not be obtained. In the present invention, carbon is used to lower the density of the positive electrode active material, and the active material is uniformly reduced in density within the positive electrode, thereby improving the initial utilization factor of the positive electrode active material. Furthermore, by having antimony present at the same time, the structure of the low-density positive electrode active material was maintained, and it was possible to obtain a battery in which the utilization rate did not decrease even after many cycles. Therefore, in the present invention in which carbon and antimony are simultaneously present, it is presumed that the utilization factor after 100 cycles could be maintained even if the positive electrode active material density was lowered.

When Sb and carbon were included, the operation was over 100 cycles even at a density of 3.16 g / cm ³ , but when neither Sb nor carbon was contained, the lead storage battery could not withstand 100 cycles at 3.16 g / cm ³ . This means that a lower density positive electrode active material can be used by containing carbon and Sb, and a better result was obtained at 3.16 g / cm ³ , so a more preferable range of density is, for example, 3.16g / cm ³ or more.

  Table 7 shows the relationship between the specific gravity of the electrolyte at 20 ° C (charged state) and the positive electrode utilization rate after 100 cycles. In the case of containing Sb and carbon, the additive-free product has a higher specific gravity, and it is more difficult to maintain the positive electrode utilization rate. The specific gravity of was found to be preferably 1.30 or more at 20 ° C. More preferably, it is 1.30 or more and 1.34 or less at 20 ° C.

  Table 8 shows the relationship between the test temperature and the positive electrode utilization rate after 100 cycles when the specific gravity of the electrolytic solution is 1.32. It has been found that when Sb and carbon are contained, the positive electrode utilization rate is easily maintained even at low temperatures.

  Table 9 shows the amount of sediment (precipitate) after 1000 cycles in the electrolytic solution having a specific gravity of 1.32. The amount of sediment is an indicator of softening and dropping of the positive electrode active material. When the density of the positive electrode active material is lowered, the sediment increases. However, when Sb and carbon are added, the sediment can be reduced even if the density is lowered.

Figure 10 shows that the positive electrode active material density is 3.41 g / cm ³ , the specific gravity of the electrolyte is 1.320, the positive electrode utilization rate after 100 cycles in a 30 ° C water bath is 100% for the additive-free product containing neither carbon nor Sb. The relative values are shown for the clad type and paste type. Carbon concentration and Sb concentration are in units of mass%. In the example containing 0.3 mass% carbon and 0.2 mass% Sb, the positive electrode utilization rate increased after 100 cycles, and more than the sum of the increase by 0.3 mass% carbon and the increase by 0.2 mass% Sb. Largely, the positive electrode utilization rate increased. Furthermore, the increase in positive electrode utilization after 100 cycles was more marked in the clad type than in the paste type.

  Table 10 shows how the utilization rate of the positive electrode after 100 cycles changes depending on the carbon content, and shows the change in the utilization rate of the positive electrode with respect to 0.1 mass% of carbon. The change in the utilization rate due to the carbon content increases as the carbon content decreases.In the section where the carbon content is 0.6 mass% to 1.0 mass%, the utilization rate is almost constant regardless of the carbon content, and the carbon content is When it exceeds 1.0 mass%, it turns out that a utilization rate begins to fall.

  Table 11 shows how the initial value of the positive electrode utilization rate changes depending on the carbon content. It can be seen that when the carbon content exceeds 1.0 mass%, the initial value of the utilization rate starts to decrease.

  A paste type positive electrode plate was made in the same manner as in the example, and the maintenance rate of the positive electrode utilization rate of the lead storage battery was evaluated. Similar to the clad type, the utilization rate after 100 cycles can be kept high with carbon and Sb.

  In addition, electrolyte solution may contain well-known additives, such as aluminum ion, sodium ion, and lithium ion, and a storage battery is good also as a control valve type. In this specification, the specific gravity of the electrolyte is indicated by specific gravity at 20 ° C.

Quantitative method for Sb element and carbon, etc. A quantitative method for Sb element and the like, and a method for measuring the density of the positive electrode material will be described below. The positive electrode is taken out from the fully charged lead acid battery, the sulfuric acid content is removed by washing with water, and the dry weight is measured. 10 g of the positive electrode active material is taken out from the positive electrode, dissolved in a solution of 20 g of tartaric acid and 20 mL of (1 + 3) nitric acid under heating, and filtered. Note that (1 + 3) nitric acid is a 1: 3 mixture of concentrated nitric acid and ion-exchanged water. The filtrate is diluted with ion-exchanged water, atomic absorption measurement is performed by ICP, and Sb content and Pb content are obtained by a calibration curve.

  The solid content separated by filtration is extracted with pure water, and separated for each type of solid content by centrifugation. Accordingly, graphite, expanded graphite, activated carbon, etc. can be separated according to the density of carbon. When a fiber component or the like is included, it can be separated from carbon due to a difference in density. If the density difference is small and the separation is incomplete, such as graphite and carbon black, the separation is performed again by centrifugation. The type of carbon can be confirmed with an electron microscope.

Method for Measuring Positive Electrode Material Density The density of the electrode material is measured as follows. Disassemble and take out fully formed and fully charged electrodes, wash with water and dry. The apparent volume v per gram and the total pore volume u per gram are measured by mercury porosimetry with the electrode material in an unground state. The apparent volume v is the sum of the solid volume of the electrode material and the closed pore volume. A container with a known volume V1 is filled with the electrode material, and a volume V2 corresponding to a pore diameter of 100 μm or more is measured by mercury porosimetry. Continue to inject mercury, measure the total pore volume u, set (V1-V2) -u to the apparent volume v, and set the density d of the positive electrode material to d = 1 / (v + u) = 1 / (V1 -V2).

Claims (5)

A lead acid battery,
A lead-acid battery, wherein the positive electrode material contains Sb and carbon. A lead acid battery,
A lead storage battery characterized in that the positive electrode material contains 0.05 mass% or more of Sb and 0.05 mass% or more of carbon.   The lead acid battery according to claim 1 or 2, wherein the carbon includes at least one of graphite, expanded graphite, activated carbon, and coke. The lead acid battery according to claim 1, wherein the density of the positive electrode material is 3.45 g / cm ³ or less.   The lead acid battery according to any one of claims 1 to 4, wherein the positive electrode is a clad type.