JP5787167B2 - Liquid lead-acid battery - Google Patents

Description

This invention relates to the liquid-type lead-acid battery.

  An idling stop has been proposed to improve the fuel efficiency of automobiles. In the idling stop, the engine is stopped when the vehicle is stopped, and all the electric power of the electric components and the like that are stopped is supplied from the storage battery. In order to further improve fuel economy, for example, it is considered that the alternator is not operated during acceleration and constant speed, but the alternator is used as a power regenerative brake during deceleration and the storage battery is charged to use energy efficiently. Yes. However, the storage battery is used in a state of insufficient charge. The inventor investigated the behavior of the liquid lead-acid battery in such a use mode, and found that the battery reached the end of its life by softening the positive electrode active material.

Here is related prior art. Patent Document 1 (Japanese Patent Laid-Open No. 2006-66283) describes a sealed lead-acid battery for cycle use in which the density of the positive electrode active material paste is 4.4 to 4.9 g / cm ³ and the positive electrode active material is 0.01 to 0.1% Bi. Is disclosed. In Patent Document 1, Bi increases the adhesion between active materials and between the active material and the lattice, and optimizes the packing density of the positive electrode active material paste so as not to inhibit the diffusion of sulfate ions. Further, Patent Document 1 describes that the positive electrode active material can be prevented from being softened and dropped by accommodating the electrode plate group in the battery case at a group pressure of 40 to 100 KPa.

JP2006-66283

  An object of the present invention is to improve the durability of a lead-acid battery and to prevent a decrease in capacity.

The present invention includes a positive electrode plate composed of a positive electrode active material and a positive electrode lattice, a negative electrode plate composed of a negative electrode active material and a negative electrode lattice, a separator separating the positive electrode plate and the negative electrode plate, a positive electrode plate, a negative electrode plate, and a separator. In a liquid lead-acid battery for an idling stop vehicle comprising:
The positive electrode active material has a density of 4.4 g / cm ³ or more and 4.8 g / cm ³ or less in a converted state, and Sn is converted into metal Sn and contains 0.05 mass% or more and 1.0 mass% or less ,
The negative electrode active material is characterized by containing carbon black in an amount of 0.2 mass% or more and 1 mass% or less with respect to 100 mass% of the spongy lead in the negative electrode active material when the negative electrode active material is already formed .

In the present invention, the density of the formed positive electrode active material is set to 4.4 g / cm ³ or more and 4.8 g / cm ³ or less to improve durability when used in a state of insufficient charge (see FIG. 1). As a result, the capacity of the liquid lead-acid battery decreases, so that the decrease in capacity is suppressed by adding 0.05 mass% or more and 1.0 mass% or less of Sn in the positive electrode active material in terms of metal Sn (see FIG. 3). .

Preferably, the positive electrode active material contains 0.1 mass% or more and 1.0 mass% or less of Sn in terms of chemical conversion in terms of metal Sn. Within this range, the capacity of the liquid lead-acid battery can be particularly increased, and the amount of electrolyte can be reduced relatively (see FIG. 3). Preferably, the liquid electrolyte contains Al ³⁺ ions.

Preferably, the positive electrode active material has a Bi content of less than 0.01 mass% in the already formed state. In the present invention, by setting the density of the positive electrode active material to 4.4 g / cm ³ or more and 4.8 g / cm ³ or less, softening of the positive electrode active material is prevented and Bi is not required.

  Preferably, at least one surface of the positive electrode lattice is coated with a Pb—Sb alloy foil. The Pb-Sb alloy foil increases the adhesion between the positive electrode active material and the positive electrode lattice, and prevents the positive electrode active material from falling off due to softening.

In the characteristic diagram showing the relationship between the density of the positive electrode active material and the initial capacity and life in the examples, the positive electrode active material contains 0.1 mass% Sb in metal conversion and 0.25 mass% Sn in metal conversion In the characteristic diagram showing the relationship between the Sb content of the positive electrode active material and the initial capacity and life in the examples, the positive electrode active material contains 0.25 mass% Sn in terms of metal, and the density is 4.6 g / cm ³ In the characteristic diagram showing the relationship between the Sn content of the positive electrode active material and the initial capacity and life in the examples, the positive electrode active material contains 0.1 mass% Sb in terms of metal, and the density is 4.6 g / cm ³ The figure which shows the durability test conditions of the lead acid battery in an Example The figure which shows the durability test conditions of the lead storage battery in the conventional example Block diagram of battery system of embodiment

In the following, an optimum embodiment of the present invention will be shown. In carrying out the invention of the present application, the embodiments can be appropriately changed in accordance with common sense of those skilled in the art and disclosure of prior art. In the embodiment, an example is shown in which Sb is contained in the positive electrode active material to prevent stratification of the electrolytic solution, but Sb may not be contained. For example, when the Sn concentration in the positive electrode active material is about 0.5 to 1.0 mass% in terms of metal, gas such as H ₂ can be generated during charging by Sn to prevent stratification. Furthermore, by stacking Pb—Sb foils on both sides of the positive grid, gas such as H ₂ can be generated to prevent stratification.

The embodiment will be described with reference to FIGS. Sb ₂ O ₃ and SnSO ₄ and a synthetic resin fiber as a reinforcing agent were added to the lead powder produced by the ball mill method and kneaded with water and sulfuric acid to obtain a positive electrode active material paste. Moreover, the density of the positive electrode active material paste was changed by adjusting the amounts of water and sulfuric acid during kneading. The lead powder may be produced by the Barton method or the like, and the content of lead dan in the lead powder is arbitrary. An appropriate Sb compound such as Sb ₂ (SO ₄ ) ₃ may be added instead of Sb ₂ O ₃ , and similarly an appropriate Sn compound such as SnO ₂ may be added instead of SnSO ₄ . Further, for example, an alloy of Pb, Sb, and Sn may be mixed with the metal Pb of the lead powder raw material.

  Pb-Ca positive electrode grid with Pb-Sb alloy foil (thickness 20μm, Sb 5mass% contained, the rest being Pb) on one side (composition of the part excluding Pb-Sb alloy foil is Ca 0.07mass%, Sn 1.5mass % Content, the balance being Pb, manufactured by rotary expanding), the positive electrode active material paste was filled, and aged and dried at 50 ° C. to obtain an unformed positive electrode plate. The Pb—Sb alloy foil may be laminated on both sides of the positive electrode grid. By laminating the Pb—Sb alloy foil on at least one surface of the positive electrode lattice, the adhesion between the positive electrode active material and the positive electrode lattice can be improved, thereby suppressing the softening of the positive electrode active material. However, the Pb—Sb alloy foil need not be laminated.

The composition of the formed positive electrode active material was set to the following range. Sb is 0～0.5Mass% in terms of metal, Sn is 0～2Mass% in terms of metal, synthetic resin fibers 0.1mass%, lead oxide remainder composed mainly of lead dioxide PbO _2, density 4.2~5g / cm ³ . The mass of the formed positive electrode active material is the mass when the active material is taken out from the formed positive electrode plate, washed and dried. When a part of the positive electrode active material is changed to lead sulfate, it is returned to PbO ₂ by charging, and the mass of the positive electrode active material is measured. The content of Sb and Sn can be elementally analyzed by emission spectroscopic analysis or the like. The density of the positive electrode active material is almost the same regardless of whether it is filled in the grid or taken out from the grid. For example, the bulk density of the positive electrode active material taken out from the electrode plate and washed with water and dried, for example, pore distribution by mercury intrusion method What is necessary is just to measure by. The mercury intrusion method uses a phenomenon in which mercury is intruded from a large pore to a small pore by applying pressure. The positive electrode active material may contain impurities or additives other than Sb, Sn and synthetic resin fibers, but the total amount thereof is, for example, 1 mass% or less. In some cases, Bi is mixed as an impurity of lead. However, in the present invention, Bi is not used, so the Bi content in the positive electrode active material is set to less than 0.01 mass%, for example.

Lead powder produced by the ball mill method is mixed with carbon black such as ketjen black or acetylene black, BaSO ₄ , synthetic resin fiber of reinforcing agent and lignin sulfonic acid, kneaded with water and sulfuric acid, and negative electrode active A material paste was obtained. The negative electrode active material paste is filled into a Pb-Ca negative electrode lattice (Ca 0.05mass%, Sn 0.5mass% contained, the remainder is Pb, manufactured by rotary expansion), and is aged and dried at 50 ° C, unformed Negative electrode plate. The composition of the chemical conversion already negative electrode active material, to spongy lead 100 mass%, carbon black not more than 0.3 mass%, BaSO ₄ is 0.5 mass%, the synthetic resin fibers 0.1mass%, the lignin sulfonate is 0.15 mass%. Carbon black is used for preventing sulfation of the negative electrode active material, and the amount added is 0.2 mass% or more and 1 mass% or less with respect to 100 mass% of the spongy lead. The amount of BaSnO ₄ , synthetic resin fiber, and lignin sulfonic acid is arbitrary.

A negative electrode plate is wrapped with a polyethylene separator having fine pores, and eight negative electrode plates and seven positive electrode plates are alternately laminated to form an electrode plate group, and the six electrode plate groups are set in a polypropylene battery case, The electrolytic solution was poured into a liquid lead acid battery (hereinafter simply referred to as a lead acid battery). The electrode group is immersed in the electrolytic solution, and the electrolytic solution is fluid. With sulfuric acid having a specific gravity of 1.285 at the electrolyte 20 ° C., Al ³⁺ is ion was 0.1 mol / L contained as _{Al 2 (SO 4) 3,} Li + ions to improve the low temperature high rate discharge performance and the like on the other May be contained as Li ₂ SO _{4 in an} amount of about 0.1 mol / L. The electrolytic solution may contain other components such as Na ⁺ ions and lignin eluted from the negative electrode active material. The chemical conversion was performed by battery case chemical conversion, for example, with an electric quantity of 200% of the theoretical capacity of the positive electrode active material.

  Three lead storage batteries each having different density, Sb content, and Sn content of the positive electrode active material were used, and the 5-hour rate capacity (JIS D 5301 9.5.2b)) was measured as the initial capacity. Next, an endurance test was performed under the conditions shown in FIG. The endurance test in Fig. 4 is the same as the idle stop life test (SBA S 0101 9.4.5) according to the battery industry association standard shown in Fig. 5, with the charge time per cycle reduced from 60 seconds to 30 seconds and every 100 cycles. In addition, it was changed to perform supplementary charging for 20 minutes at 14.5V. And when the voltage at the time of discharge became less than 7.2V, it was considered as the life, and the number of cycles until reaching the life was measured. Further, the density of the upper part of the electrolytic solution was measured during the durability test, and the degree of stratification of the electrolytic solution was evaluated. The stratification referred to here is a phenomenon in which sulfuric acid settles in the lower part of the electrolytic solution and the sulfuric acid concentration becomes different between the upper and lower parts of the electrolytic solution. Moreover, the storage battery which reached the end of its life was disassembled, and the degree of softening of the positive electrode active material was evaluated from the state of the positive electrode active material, and the degree of sulfation was evaluated from five levels of lead sulfate in the negative electrode active material, respectively. The cause of the lifetime was all due to softening of the positive electrode active material.

1 to 3 show the results as relative values, and the results are the average values of three lead-acid batteries. In FIG. 1, the positive electrode active material has an Sb concentration of 0.1 mass% and an Sn concentration of 0.25 mass%, and in FIG. 2, the positive electrode active material has an Sn concentration of 0.25 mass% and a density of 4.6 g / cm ³ at the stage of chemical conversion. It is. In FIG. 3, the positive electrode active material has an Sb concentration of 0.1 mass% and a density of 4.6 g / cm ³ at the stage of chemical conversion.

As is clear from FIG. 1, as the density of the ready-made positive electrode active material increased, the life in the durability test of FIG. 4 increased, while the 5-hour rate capacity decreased. When the positive electrode active material density was in the range of 4.4 g / cm ^{3 to} 4.8 g / cm ³ , the lifetime and the 5-hour rate capacity changed gradually with respect to the density of the positive electrode active material. When the density exceeded 4.8 g / cm ³ , the capacity decreased rapidly, and when the density was less than 4.4 g / cm ³ , the life decreased rapidly. The density having both capacity and life is 4.4 g / cm ³ or more and 4.8 g / cm ³ or less. When the storage battery was disassembled after the test, it was found that the cause of the lifetime was softening of the positive electrode active material, and the softening was slower as the density of the positive electrode active material was higher.

  As is clear from FIG. 2, the lifetime rises sharply due to the presence of Sb in the positive electrode active material, and is effective when the Sb concentration in the positive electrode active material is 0.01 mass% or more, and has a significant effect at 0.03 mass%. The effect was saturated at mass%, and the life decreased slightly when it exceeded 0.3mass%. On the other hand, the amount of electrolyte decrease gradually increased with the Sb concentration until the Sb concentration reached 0.3 mass%, and rapidly increased when the Sb concentration exceeded 0.3 mass%. From these facts, it was found that the Sb concentration is preferably 0.03 mass% or more and 0.3 mass% or less, and particularly preferably 0.05 mass% or more and 0.2 mass% or less. Regarding the density of the electrolyte during the durability test, the stratification was remarkable when the Sb concentration was 0 mass% and 0.01 mass%, and the stratification was suppressed when the Sb concentration was 0.03 mass% or more, and even if the Sb concentration was increased to 0.3 mass% or more, Thus, stratification could not be suppressed. Further, when the storage battery was disassembled after the durability test, it was found that the cause of the life was softening of the positive electrode, and when the Sb concentration was 0.03 mass% or more, preferably 0.05 mass% or more, the softening was suppressed. When the softening has progressed, the softening was significant at the top of the positive electrode plate.

Sb in the positive electrode active material has an effect of increasing the adhesion between the positive electrode active material and the positive electrode lattice and suppressing softening. In addition, Sb in the positive electrode active material partly moves to the negative electrode side, and generates H ₂ gas and the like during charging, thereby suppressing the stratification of the electrolyte. In Examples, when about 0.1 mass% of Sb was contained in the positive electrode active material, generation of H ₂ gas started when the state of charge during charging reached about 90%. When the electrolytic solution is stratified, the sulfuric acid concentration of the electrolytic solution is lowered at the upper part of the electrode plate, so that it is difficult to discharge with a large current. When charging / discharging is repeated in this state, the softening of the positive electrode active material tends to proceed particularly at the upper part of the electrode plate. Therefore, by containing Sb in the positive electrode active material and generating H ₂ gas or the like, the stratification of the electrolyte was suppressed and the life performance was improved.

  Since the storage battery of the example is operated in a state of insufficient charging, the liquid reduction is not as serious as that of a normal lead storage battery. For this reason, by increasing the Sb concentration, it was possible to prevent stratification of the electrolyte and softening of the positive electrode active material.

It is known that lead storage batteries for idling stop vehicles reach the end of their life due to sulfation of the negative electrode active material. However, in the examples, since sulfation was suppressed by containing Al ³⁺ ions in the electrolytic solution and carbon black in the negative electrode active material, the lifetime was reached by softening of the positive electrode active material instead of sulfation.

  As shown in FIG. 3, the 5-hour rate capacity increased due to Sn in the positive electrode active material. As shown in FIG. 1, when the density of the positive electrode active material is increased, the 5-hour rate capacity decreases, but by adding Sn to the positive electrode active material, the 5-hour rate capacity could be maintained within an allowable range. . When Sn is contained in the positive electrode active material in excess of 1 mass%, the amount of liquid decrease increases remarkably, and if it is less than 0.05 mass%, the effect is slight, so the Sn content in the positive electrode active material is 0.05 mass% or more and 1 mass % Or less, particularly 0.1 mass% or more and 1 mass% or less is preferable. When Sb and Sn were contained in the positive electrode active material at the same concentration, the amount of liquid reduction was more remarkable when Sb was contained.

As described above, in the embodiment,
・ Suppressing softening by increasing the density of the positive electrode active material,
Positive-electrode active with a substance Sb that is contained in increasing the adhesion between the positive electrode active material and the grid, also suppresses the stratification of the electrolyte to generate H ₂ gas or the like by moving the Sb to the negative electrode.
Further, the capacity is increased by Sn contained in the positive electrode active material to compensate for the decrease in capacity caused by increasing the density of the positive electrode active material.
By combining the above mechanisms, the durability of the lead storage battery used in a state of insufficient charge is improved while maintaining the capacity equivalent to that of the conventional lead storage battery.

  FIG. 6 shows a battery system incorporating the lead storage battery 2 of the embodiment. 6 is an automobile engine, 8 is an alternator, and 4 is a lead-acid battery control device. Reference numeral 10 denotes a load such as an ignition device, a starter motor, and other electrical components. A main control unit 12 controls the engine 6 and the alternator 8 and instructs the control device 4 to charge or discharge the lead storage battery. The control device 4 indicates that the remaining capacity of the lead storage battery 2 has decreased. It is detected by the terminal voltage or the like, and the main controller 2 is requested to operate the alternator 8. The controller 4, the lead storage battery 2 and the load 10 constitute a battery system.

  In the idling stop vehicle incorporating the battery system of FIG. 6, the charging of the lead storage battery 2 by the alternator 8 is stopped at the time of stopping, acceleration and constant speed driving, and the load 10 is driven by the power of the lead storage battery 2. The alternator 8 is operated during deceleration to operate the load 10 and charge the lead storage battery 2. Further, when the remaining capacity of the lead storage battery 2 decreases, for example, the alternator is operated even during constant speed running, and the lead storage battery 2 is charged. The test conditions in FIG. 4 simulate the operation of the battery system in FIG. 6. In the embodiment, a lead storage battery that can be used in such a battery system is obtained.

2 Liquid lead-acid battery 4 Controller 6 Engine 8 Alternator 10 Load 12 Main controller

Claims (5)

A positive electrode plate made of a positive electrode active material and a positive electrode lattice, a negative electrode plate made of a negative electrode active material and a negative electrode lattice, a separator separating the positive electrode plate and the negative electrode plate, and immersing and flowing the positive electrode plate, the negative electrode plate and the separator A liquid lead-acid battery for an idling stop vehicle comprising:
The positive electrode active material has a density of 4.4 g / cm ³ or more and 4.8 g / cm ³ or less in a converted state, and Sn is converted into metal Sn and contains 0.05 mass% or more and 1.0 mass% or less ,
A liquid lead-acid battery comprising carbon black in an amount of 0.2 mass% to 1 mass% with respect to 100 mass% of spongy lead in the negative electrode active material when the negative electrode active material has been converted .   Preferably, the positive electrode active material contains 0.1 mass% or more and 1.0 mass% or less of Sn in terms of being converted into metallic Sn in the already formed state. Liquid electrolyte is Al ³⁺ The liquid lead-acid battery according to claim 1 or 2, comprising ions.   The liquid lead acid battery according to any one of claims 1 to 3, wherein the positive electrode active material has a Bi content of less than 0.01 mass% in a state of being chemically formed.   The liquid lead acid battery according to any one of claims 1 to 4, wherein at least one surface of the positive electrode grid is coated with a Pb-Sb alloy foil.

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