JP2013131377A - Lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead storage battery which is excellent in charging receiving performance.SOLUTION: A lead storage battery comprises an electrolyte containing a rubidium ion of 10-350 mmol/L and a sodium ion of 2-30 mmol/L.

Description

  The present invention relates to a lead storage battery excellent in charge acceptance performance.

  Conventional lead-acid batteries for automobiles are discharged with a large current when the engine is started. However, after the engine is started, power is supplied to various electrical components by a generator driven by the engine and lead after a large current is discharged. Since the storage battery is charged, it is rarely used in a discharged state even though it is used in an overcharged state. Therefore, in the conventional lead-acid battery, it was a point of improving the life performance to suppress a decrease in the life performance due to overcharging.

  Recently, however, as global environmental issues have attracted attention, automobiles have been challenged to improve fuel economy and reduce exhaust emissions, and the usage conditions for lead-acid batteries installed in automobiles have changed significantly. . One of them is the emergence of vehicles (charging control vehicles) equipped with a charging control system. In a charge control vehicle, when a predetermined charge level is reached, power generation of the alternator is stopped, the engine load is reduced, and fuel efficiency is improved. In order to achieve high fuel efficiency in a charge-controlled vehicle, a lead storage battery that can efficiently achieve a high charge level, that is, a lead storage battery with high charge acceptance performance is indispensable.

  By the way, in the conventional lead-acid battery, alkali metal ions such as sodium ions are contained in the electrolytic solution in order to suppress penetration short circuit due to dissolution and precipitation of lead (dendritic precipitation) on the negative electrode active material. (Patent Document 1).

JP-A-8-64226

  However, as a result of investigations by the present inventors, it has been found that the addition of alkali metal ions into the electrolyte also affects the charge acceptance performance, and the effect varies greatly depending on the type of alkali metal ions.

  Therefore, in view of the above situation, the present invention is intended to provide a lead storage battery excellent in charge acceptance performance.

  As a result of intensive studies, the inventor has included a state in which the charge acceptance performance is good while maintaining the permeation-resistant short-circuit performance by containing rubidium ions in the electrolyte while keeping the concentration of sodium ions in the electrolyte low. As a result, the present invention has been completed.

  That is, the lead acid battery according to the present invention is characterized by including an electrolytic solution containing 10 to 350 mmol / L rubidium ions and 2 to 30 mmol / L sodium ions. The electrolytic solution preferably contains 50 to 100 mmol / L of rubidium ions and 2 to 10 mmol / L of sodium ions.

  The effect of the present invention is more noticeable when the electrolyte solution has a fully charged sulfuric acid concentration of 35.1 to 43.1% by mass. Among them, an electrolytic solution in which the present invention is effective is one having a fully charged sulfuric acid concentration of 35.1 to 38.6% by mass.

  Further, it is more preferable that the electrolytic solution has a sulfuric acid concentration of 16% by mass or more when discharged to 1.75 V at a 20 hour rate current.

  The rubidium ion is preferably derived from rubidium sulfate.

  Since this invention consists of the structure mentioned above, the lead storage battery excellent in the charge acceptance performance suitable for charge control vehicles can be obtained.

  Below, the embodiment of the lead acid battery concerning the present invention is described.

  The lead storage battery according to the present invention includes, for example, a positive electrode plate containing lead dioxide as a main component of an active material, a negative electrode plate containing lead as a main component of an active material, and a porous or non-woven separator interposed between these electrode plates A liquid type or control valve type equipped with an electrode plate group consisting of the following: The electrode plate group is immersed in an electrolyte containing dilute sulfuric acid as a main component.

  The negative electrode plate includes a lattice body made of a Pb—Sb alloy, a Pb—Ca alloy, or the like, and is formed by filling the lattice body with a paste-like active material. On the other hand, when the positive electrode plate is a paste type, it is formed in the same manner as the negative electrode plate. However, when it is a clad type, the positive electrode plate is formed between a tube made of glass fiber or the like and a lead alloy core metal. Formed by filling material. Each of these constituent members can be appropriately selected from known ones according to the purpose and use.

  The electrolytic solution in the present invention contains 10 to 350 mmol / L rubidium ion and 2 to 30 mmol / L sodium ion, preferably 50 to 100 mmol / L rubidium ion and 2 to 10 mmol / L sodium. It contains ions. By containing rubidium ions and sodium ions in the electrolyte within this concentration range, a lead storage battery having high charge acceptance performance can be obtained.

  When the sodium ion concentration is 2 to 30 mmol / L and the rubidium ion concentration is less than 10 mmol / L, the content of rubidium ions is insufficient and the positive electrode is largely polarized, so that sufficient charge acceptance performance is obtained. I can't. On the other hand, when the sodium ion concentration is 2 to 30 mmol / L and the rubidium ion concentration exceeds 350 mmol / L, the polarization of the negative electrode increases due to the presence of excess rubidium ions, and the charge acceptance performance decreases.

  On the other hand, when the rubidium ion concentration is 10 to 350 mmol / L and the sodium ion concentration exceeds 30 mmol / L, the polarization of the negative electrode increases and the charge acceptance performance decreases. Furthermore, since lignin is added to the negative electrode of the lead storage battery, and the lignin usually contains sodium, setting the sodium ion concentration to less than 2 mmol / L leads to a decrease in the amount of lignin, and lead Since the performance of the storage battery is significantly reduced, it is substantially difficult.

  Both the rubidium ion and the sodium ion are alkali metal ions. However, as a result of investigations by the present inventors, as shown in Table 1 described later, even if the same alkali metal ion is used, the influence on the charge acceptance performance is a metal. It was clarified that it varies greatly depending on the ion species. That is, among the alkali metal ions, rubidium ions have an action of suppressing the polarization of the positive electrode during charging, lithium, sodium and cesium ions have no action of suppressing the polarization of the positive electrode, and potassium ions suppress the polarization of the positive electrode. Although it has an action, since the action of increasing the polarization of the negative electrode is too strong, as a result, only the rubidium ion has the action of improving the charge acceptance performance, and when lithium, sodium, potassium and cesium ions are contained in the electrolyte, It was found that depending on the concentration, the charge acceptance performance was adversely affected. The charge acceptance performance described here refers to the charge acceptance performance within a relatively long time of several minutes or more, not the charge acceptance performance within a time of about several seconds such as regenerative charging.

  In addition, simulation of charging by driving the engine during cruising in a charge-controlled vehicle, the charge acceptance performance is 90% SOC (State of charge: the ratio of the actual charge amount to the full charge amount) 90% lead storage battery Was defined as a charge amount of electricity entering for 3 minutes when a constant current-constant voltage charge was performed at a maximum current of 1 CA with a limit voltage of 2.33 V. When the charge acceptance performance is evaluated based on this definition, the charge acceptance performance is lower when an electrolyte solution having a higher sulfuric acid concentration at full charge is used. When the sulfuric acid concentration exceeds 43.1% by mass, rubidium ions and sodium ions are used. However, even if the necessary amount was contained, sufficient charge acceptance performance could not be obtained. And the sulfuric acid density | concentration which is easy to express the effect of this invention was 35.1-38.6 mass%. On the other hand, when the sulfuric acid concentration is less than 35.1% by mass, sufficient charge-accepting performance can be obtained without containing rubidium ions and sodium ions.

  Conventional lead-acid battery electrolytes usually contain sodium ions and other alkali metal ions at a concentration higher than 30 mmol / L in order to suppress osmotic short-circuiting, and the content of alkali metal ions is low. If it is low, it is difficult to obtain sufficient penetration resistance short-circuit performance. On the other hand, the cause of the occurrence of the osmotic short circuit is an increase in the lead ion concentration due to a decrease in the sulfuric acid concentration. Therefore, the osmotic short circuit is less likely to occur when the sulfuric acid concentration at the end of the discharge is higher. For this reason, when an electrolytic solution having a sulfuric acid concentration of 16% by mass or more when discharged to 1.75 V at a 20 hour rate current is used, it is preferable that an osmotic short circuit hardly occurs.

  Moreover, in order to suppress an osmotic short circuit, it is preferable to add the rubidium ion in electrolyte solution as rubidium sulfate. By adding rubidium ion to the electrolyte as rubidium sulfate, even if the sulfate ion derived from dilute sulfuric acid in the electrolyte is exhausted by deep discharge, the sulfate ion derived from rubidium sulfate imparts conductivity to the electrolyte. As a result, the resistance of the electrolytic solution can be kept low, and the deterioration of the charge recovery performance can be suppressed. Moreover, since the dissolution of lead sulfate in the electrolytic solution can be suppressed by increasing the sulfate ion concentration, an osmotic short circuit can be prevented.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

<Test 1> Influence of each alkali metal ion species on charge acceptance performance One positive electrode plate and two negative electrode plates produced by a conventional method are used, and the test battery is a commonly used polyethylene separator (thickness : 0.65 mm), the negative electrode plate was wrapped (the two ends of the separator were thermally welded), and the positive electrode plate and the negative electrode plate were alternately stacked to assemble with no compression. Thereafter, 31% by mass (corresponding to a specific gravity of 1.23, 20 ° C.) of diluted sulfuric acid was added, and 300% of the theoretical electricity of the positive electrode active material was energized. Subsequently, the sulfate of each alkali metal ion was added to the electrolyte solution so that the alkali metal ion concentration in the electrolyte solution became a predetermined value. The sulfuric acid concentration at this time is 38% by mass (corresponding to a specific gravity of 1.285, 20 ° C.).

The charge acceptance test was conducted under the following conditions.
・ Discharge: 0.2CA × 30min
・ Left: 12 hours ・ Charging: Maximum current: 1 CA
・ Limited voltage: 2.33V
・ Evaluation of charge acceptance performance: 3 minutes charge electricity

  Here, the charge acceptance performance is the amount of electricity charged for 3 minutes when a 90% SOC lead acid battery is left for 12 hours and charged at a constant current-constant voltage at a maximum current of 1CA at a limit voltage of 2.33V. Based on this definition, the charge acceptance performance was evaluated. The obtained results are shown in Table 1. In addition, the charge acceptance performance of each sample was represented by the relative value which set the charge electric quantity of the sample which does not add an alkali metal ion to electrolyte solution as 100.

  As shown in Table 1, it was revealed that only 10 to 350 mmol / L of rubidium ion has an effect of improving the charge acceptance performance.

<Test 2> Effect of Rubidium Ion Concentration and Sodium Ion Concentration on Charge Receiving Performance One positive electrode plate and two negative electrode plates produced by a conventional method are used, and the test battery is a commonly used PE separator. The negative electrode plate was wrapped in a U-shape (thickness: 0.65 mm), and the positive electrode plate and the negative electrode plate were alternately stacked to assemble without applying a pressing force. Thereafter, 31% by mass (corresponding to a specific gravity of 1.23, 20 ° C.) of diluted sulfuric acid was added, and 300% of the theoretical electricity of the positive electrode active material was energized. Next, sulfates of rubidium ions and sodium ions were added to the electrolytic solution so that their concentrations in the electrolytic solution became predetermined values. The sulfuric acid concentration at this time is 38% by mass (corresponding to a specific gravity of 1.285, 20 ° C.).

The charge acceptance test was performed under the following conditions.
・ Discharge: 0.2CA × 30min
・ Left: 12 hours ・ Charging: Maximum current: 1 CA
・ Limited voltage: 2.33V
・ Temperature: 25 ℃
・ Evaluation of charge acceptance performance: 3 minutes of charge electricity

  The obtained results are shown in Table 2. In Table 2, the charge acceptance performance is expressed as a relative value where the charge electricity amount for 3 minutes is 100 when the rubidium ion concentration in the electrolyte is 0 mmol / L and the sodium ion concentration is 2 mmol / L. Samples with charge acceptance performance greater than 100 were accepted.

  As shown in Table 2, it is clear that the charge acceptance performance is good only when the ion concentration in the electrolyte is 10 to 350 mmol / L for rubidium ions and 2 to 30 mmol / L for sodium ions. It was.

Claims (6)

  A lead-acid battery comprising an electrolytic solution containing 10 to 350 mmol / L rubidium ions and 2 to 30 mmol / L sodium ions.   The lead acid battery according to claim 1, wherein the electrolytic solution contains 50 to 100 mmol / L of rubidium ions and 2 to 10 mmol / L of sodium ions.   The lead acid battery according to claim 1 or 2, wherein the electrolyte solution has a fully charged sulfuric acid concentration of 35.1 to 43.1% by mass.   The lead acid battery according to claim 3, wherein the electrolytic solution has a fully charged sulfuric acid concentration of 35.1 to 38.6 mass%.   5. The lead acid battery according to claim 1, wherein the electrolytic solution has a sulfuric acid concentration of 16% by mass or more when discharged to 1.75 V at a 20 hour rate current.   The lead acid battery according to claim 1, 2, 3, 4 or 5, wherein the rubidium ion is derived from rubidium sulfate.