JP2017069010A - Lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the worsening of the cycle life (IS cycle life) in a lead storage battery.SOLUTION: A lead storage battery comprises: a positive electrode; a negative electrode; a separator interposed between the positive and negative electrodes; and an electrolyte including sulfuric acid. The negative electrode includes a titanium compound. The titanium compound is 0.01 mmol/L or more in 20°C-solubility in sulfuric acid aqueous solution of 1.28 in specific weight at 20°C. Examples of the titanium compound include metatitanic acid or its salt, titanyl sulfate and titanium sulfate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an improvement in the negative electrode of a lead storage battery.

  Lead-acid batteries are inexpensive, have a relatively high battery voltage, and provide high power, so they are used in various applications in addition to cell starters for automobiles. The lead acid battery includes a positive electrode containing lead dioxide, a negative electrode containing lead, a separator interposed between the positive electrode and the negative electrode, and an electrolyte containing sulfuric acid.

  In recent automobile applications, lead storage batteries are often used in an intermediate charging state in which the state of charge (SOC) is about 90 to 70%, such as being exposed to an idle stop state. If the battery continues to be used in such a half-charged state, the charge acceptability decreases due to the deactivation of the negative electrode active material called sulfation, and the deterioration of the battery accelerates. This is because lead sulfate gradually crystallizes and loses electrochemical activity in a chronic undercharged state. Since crystalline lead sulfate is difficult to dissolve in the electrolyte, the polarization of the negative electrode charging reaction increases. When the charge acceptability of the negative electrode is reduced, the charge capacity (charge efficiency) in a limited charge time is reduced, and the SOC is difficult to recover. Therefore, the halfway charge state continues, the SOC decreases further, and the battery deteriorates.

  Therefore, various improvements have been attempted to suppress the deactivation of the negative electrode active material by improving the charge acceptance of the negative electrode or increasing the charging efficiency.

Patent Document 1 teaches that charging efficiency is improved by adding a predetermined concentration of aluminum ion, selenium ion, titanium ion or the like to the electrolyte, and deterioration of the active material is suppressed. Patent Document 1 describes that the concentration of titanium ions in the electrolyte is 1 mmol / L to 100 mmol / L. Patent Document 2 teaches that titanium oxide or titanium dioxide is added to the positive electrode from the viewpoint of improving the active material utilization in the lead-acid battery. Patent Document 3 proposes to add a hydrophilic fine powder such as TiO ₂ to the negative electrode plate in order to suppress self-discharge during storage of the lead-acid battery.

International Publication No. 2007/036979 Pamphlet JP 63-126166 A JP-A-63-19772

  When titanium ions or the like are added to the electrolyte as in Patent Document 1, it is considered that it acts on the negative electrode and lead sulfate is easily dissolved in the electrolyte. However, as a result of investigations by the present inventors, it has been found that when a predetermined concentration of titanium ions is added to the electrolyte, it is impossible to sufficiently suppress a decrease in cycle life. In particular, the cycle life (idling stop (IS) cycle life) that repeats the idle stop state is likely to decrease.

Titanium oxide used in Patent Document 2 and Patent Document 3 hardly dissolves in the electrolyte of the lead storage battery, and therefore, even if added to the positive electrode or the negative electrode, it is not possible to improve the charge acceptability and thus the IS cycle life.
An object of the present invention is to suppress a decrease in cycle life (IS cycle life) in a lead-acid battery.

One aspect of the present invention is a lead acid battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte containing sulfuric acid,
The negative electrode includes a titanium compound,
The titanium compound relates to a lead-acid battery having a solubility at 20 ° C. of 0.01 mmol / L or higher in a sulfuric acid aqueous solution having a specific gravity of 1.28 at 20 ° C.

  According to the present invention, titanium ions eluted from the negative electrode of the lead-acid battery are adsorbed on lead sulfate of the negative electrode during charging and discharging, and sulfation of the negative electrode is suppressed. Thereby, since it can suppress that the charge acceptance of a negative electrode falls, the fall of a cycle life (IS cycle life) can be suppressed.

It is the perspective view which notched some lead acid batteries concerning one embodiment of the present invention. It is a front view of the positive electrode plate in the lead acid battery of FIG. It is a front view of the negative electrode plate in the lead acid battery of FIG.

  A lead acid battery according to an embodiment of the present invention includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte containing sulfuric acid. The negative electrode includes a titanium compound (first titanium compound). The titanium compound has a solubility at 20 ° C. of 0.01 mmol / L or more in a sulfuric acid aqueous solution having a specific gravity of 1.28 at 20 ° C.

  When charging and discharging are repeated using an electrolyte in which titanium ions are dissolved, titanium ions are reduced from the electrolyte due to the action on the negative electrode. Further, during charging / discharging, most of the titanium is deposited on the surface of the positive electrode active material, so that the resistance increases and the reversibility of charging / discharging decreases. Therefore, the IS cycle life is reduced. On the other hand, titanium oxide and titanium dioxide are not suitable for a titanium ion supply source because they have low solubility in an electrolyte (or a sulfuric acid aqueous solution that is a main component thereof).

  In the present embodiment, as described above, a titanium compound having a predetermined solubility in the electrolyte (aqueous sulfuric acid solution) is included in the negative electrode. Therefore, in the battery, the titanium compound is dissolved from the negative electrode into the electrolyte, and titanium ions are supplied into the electrolyte. Titanium ions are adsorbed to lead sulfate as a negative electrode active material during charge and discharge, and thus sulfation of the negative electrode is suppressed. Since titanium ions are continuously supplied from the negative electrode, the effect of suppressing sulfation is sustained. Therefore, the fall of the charge acceptance property of a negative electrode is suppressed. In addition, since the deposition of titanium on the positive electrode is suppressed by increasing the titanium ion concentration in the vicinity of the negative electrode active material as compared with other portions, the reversibility of charge / discharge is suppressed from being lowered. From these points, it is considered that the cycle life (IS life characteristics) is improved.

  The solubility of the titanium compound at 20 ° C. in the sulfuric acid aqueous solution having a specific gravity at 20 ° C. of 1.28 may be 0.01 mmol / L or more. From the viewpoint of sustaining the effect of titanium ions as much as possible, the solubility is preferably 0.01 to 100 mmol / L, and more preferably 0.1 to 50 mmol / L. In addition, the solubility said here introduce | transduces the quantity (for example, 100 mmol in conversion of Ti element) of a titanium compound more than a saturated density | concentration with respect to 1.0L of sulfuric acid aqueous solution whose specific gravity in 20 degreeC is 1.28, and 20 degreeC. The Ti concentration of the solution portion after standing for 7 days in the environment of

Examples of the titanium compound include titanic acid (such as metatitanic acid (H ₂ TiO ₃ )) or a salt thereof, sulfate containing titanium (such as titanyl sulfate (TiOSO ₄ ), titanium sulfate (Ti (SO ₄ ) ₂ )), or titanic acid. Hydrates (TiO ₂ .xH ₂ O (0 <x <1)) and the like can be mentioned. The metatitanic acid salt, typically a metal salt (Li ₂ TiO _3, K alkali metal salts such as _{2 TiO 3; MgTiO 3, CaTiO} 3, BaTiO 3, SrTiO 3 alkaline earth metal salts such as; PbTiO _3, ZnTiO _3, etc. ); Transition metal salts such as FeTiO ₃ , CoTiO ₃ and MnTiO ₃ . As the titanium compound, metatitanic acid or a salt thereof, titanyl sulfate, and titanium sulfate are preferable, and metatitanic acid is particularly preferable. These titanium compounds may be used individually by 1 type, and may be used in combination of 2 or more type. For example, for a sulfuric acid aqueous solution having a specific gravity of 1.28 at 20 ° C., the solubility of metatitanic acid is 2.5 mmol / L, the solubility of titanyl sulfate is 28 mmol / L, the solubility of titanium sulfate is 42 mmol / L, and Li ₂ The solubility of TiO ₃ is 6 mmol / L, the solubility of K ₂ TiO ₃ is 3 mmol / L, the solubility of BaTiO ₃ is 12 mmol / L, the solubility of PbTiO ₃ is 10 mmol / L, and the solubility of ZnTiO ₃ is 3 mmol / L.

The content of titanium in the negative electrode is, for example, 0.001 to 0.05 parts by mass, preferably 0.003 to 0.03 parts by mass with respect to 100 parts by mass of the negative electrode active material. More preferably, it is 005-0.02 mass part. When the content of titanium in the negative electrode is within such a range, the effect of improving the IS cycle life can be further enhanced. The amount of titanium in the negative electrode corresponds to the amount of titanium atoms contained in the negative electrode. The amount of titanium in the negative electrode may be increased or decreased as appropriate according to the desired IS cycle life.
In addition, content of titanium in a negative electrode here is in the lead storage battery (for example, lead storage battery after break-in charge / discharge) of an initial full charge state. A fully charged lead acid battery refers to a lead acid battery when the state of charge (SOC) is 99% or more.

  In this embodiment, since the negative electrode contains a titanium compound having a specific solubility, the titanium compound is gradually dissolved in the electrolyte. As a result, the electrolyte in the battery contains titanium ions.

  The concentration of titanium ions in the electrolyte is, for example, 0.005 mmol / L or more, preferably 0.01 mmol / L or more, or 0.03 mmol / L or more. The concentration of titanium ions in the electrolyte is preferably less than 1 mmol / L, more preferably 0.5 mmol / L or less or 0.1 mmol / L or less. These lower limit values and upper limit values can be arbitrarily combined. The concentration of titanium ions in the electrolyte is, for example, 0.005 mmol / L or more and less than 1 mmol / L, and may be 0.005 to 0.5 mmol / L or 0.01 to 0.5 mmol / L.

  When the concentration of titanium ions in the electrolyte is in the above range, the effect of suppressing titanium deposition on the positive electrode and the charge acceptability on the negative electrode can be further improved. The concentration of titanium ions in the electrolyte can be adjusted by adjusting the type of titanium compound used, the physical properties (surface area, particle size, etc.) of the titanium compound, the specific gravity of the electrolyte (or the specific gravity of the aqueous sulfuric acid solution used in the electrolyte), and the like.

The titanium ion is usually an ion containing one Ti atom and may be an anion or a cation. As the titanium ions, for example, Ti ³⁺ , Ti ⁴⁺ , TiO ^{2+ and the} like are preferable. The electrolyte may contain at least one kind of these titanium ions, or may contain two or more kinds.

Hereinafter, the lead storage battery according to the embodiment of the present invention will be described in more detail with reference to the drawings as appropriate.
(Negative electrode)
The negative electrode of a lead storage battery generally includes a negative electrode lattice (such as an expanded lattice or a cast lattice) and a negative electrode mixture containing at least a negative electrode active material and a titanium compound held in the negative electrode lattice. Lead (such as spongy lead) is used as the negative electrode active material. When producing the negative electrode, lead powder can be used as the negative electrode active material. Since the negative electrode is generally plate-shaped, it is also called a negative electrode plate.

  Examples of the material of the negative electrode grid include lead or a lead alloy. The lead alloy may include, for example, Ba, Ag, Ca, Al, Bi, Sb, and / or Sn. Among these, a lead alloy containing Ca and / or Sn is preferable, and a lead alloy containing at least Ca is also preferable from the viewpoint of mechanical strength. In the lead alloy, the content of Ca may be 0.03 to 0.10% by mass, and the content of Sn may be 0.2 to 0.6% by mass. The negative electrode lattice may have a plurality of lead alloy layers having different compositions as required.

  The negative electrode mixture may further contain a shrinkage-preventing agent (such as lignin and / or barium sulfate), a conductive agent (such as a conductive carbonaceous material such as carbon black), and / or a binder (such as a polymer binder). . The negative electrode may contain other known additives as necessary.

  The negative electrode can be formed by filling or coating a negative electrode mixture paste with a negative electrode mixture paste and preparing an unformed negative electrode by drying, followed by chemical conversion treatment. The negative electrode mixture paste contains sulfuric acid and / or water as a dispersion medium in addition to the components of the negative electrode mixture.

The drying step may be an aging drying step that dries at a temperature and humidity higher than room temperature. The drying step can be performed under known conditions.
The chemical conversion treatment can be performed by charging in a state where the positive electrode and the negative electrode before conversion are immersed in an electrolyte containing sulfuric acid in the battery case of the lead storage battery. The chemical conversion treatment can be performed before assembling the battery or the electrode plate group, if necessary.

(Positive electrode)
A positive electrode of a lead storage battery generally includes a positive electrode lattice (such as an expanded lattice or a cast lattice) and a positive electrode active material (or positive electrode mixture) held on the positive electrode lattice. Since the positive electrode is generally plate-shaped, it is also called a positive electrode plate.

  Examples of the material for the positive electrode grid include lead and lead alloys exemplified for the positive electrode grid. From the viewpoint of easily obtaining high corrosion resistance and mechanical strength, it is preferable to use a lead alloy containing Ca and / or Sn. In the lead alloy, the Ca content may be 0.01 to 0.1% by mass, and the Sn content may be 0.05 to 3% by mass. The positive electrode lattice may have a plurality of lead alloy layers having different compositions as required. For example, it is preferable to form a lead alloy layer containing Sb in the portion holding the positive electrode active material from the viewpoint of suppressing the deterioration of the positive electrode active material. 0.001 to 0.002 mass% may be sufficient as content of Sb in a positive electrode grid | lattice, for example.

Lead oxide (PbO ₂ ) is used as the positive electrode active material. The positive electrode active material is usually used in the form of a powder.
The positive electrode mixture may contain a conductive agent (such as a conductive carbonaceous material such as carbon black) and / or a binder (such as a polymer binder) in addition to the positive electrode active material. The positive electrode may contain a known additive as required.
The positive electrode can be formed according to the case of the negative electrode.

(Separator)
Examples of the separator include a microporous membrane or a fiber sheet (or mat). As a polymer material which comprises a microporous film or a fiber sheet, what has acid resistance is preferable, and polyolefin, such as polyethylene and a polypropylene, can be illustrated. The fiber sheet may be formed of polymer fibers (fibers formed of the polymer material) and / or inorganic fibers such as glass fibers.
The separator may contain an additive such as a filler and / or carbon, if necessary.

(Electrolytes)
The electrolyte contains sulfuric acid and is usually an aqueous sulfuric acid solution. The specific gravity of the electrolyte is, for example, 1.1~1.35g / cm ^3, is preferably 1.2~1.35g / cm ^3, to be 1.25~1.3g / cm ³ Further preferred. When the specific gravity of the electrolyte is within such a range, the amount of titanium compound dissolved can be easily adjusted, and the concentration of titanium ions in the electrolyte can be easily maintained within an appropriate range. In the present specification, the specific gravity of the electrolyte is the specific gravity at 20 ° C. As for the specific gravity of the electrolyte in the battery, it is desirable that the specific gravity of the electrolyte in a fully charged battery (SOC is 99% or more) be in the above range.

  The electrolyte may include a solid titanium compound (second titanium compound) as necessary. Examples of the second titanium compound include metatitanic acid, titanic acid hydrate, and / or titanate. The form of the second titanium compound is not particularly limited, but may be powder, granule, pellet or the like. The second titanium compound only needs to be immersed in the electrolyte, and may be dispersed in the electrolyte. The amount of the second titanium compound can be adjusted as appropriate so that the concentration of titanium ions in the electrolyte during charging and discharging falls within the above range.

  A lead storage battery can be produced by housing an electrode plate group and an electrolyte in a battery case (battery case). The electrode plate group can be produced by superimposing a plurality of positive electrodes and a plurality of negative electrodes so that the positive electrodes and the negative electrodes are alternately arranged with a separator interposed therebetween. The separator may be disposed so as to be interposed between the positive electrode and the negative electrode, and a bag-shaped separator is used, or a sheet-shaped separator is folded in half (U-shaped), and one electrode is sandwiched between the other. You may overlap with an electrode. A plurality of electrode plate groups may be accommodated in the battery case.

FIG. 1 is a partially cutaway perspective view of a lead storage battery according to an embodiment of the present invention. 2 is a front view of the positive electrode plate of FIG. 1, and FIG. 3 is a front view of the negative electrode plate of FIG.
The lead storage battery 1 includes an electrode plate group 11 and an electrolyte (not shown), which are accommodated in a battery case 12. More specifically, the battery case 12 is partitioned into a plurality of cell chambers 14 by partition walls 13, and each cell chamber 14 stores one electrode plate group 11 and also stores an electrolyte. The electrode plate group 11 is configured by laminating a plurality of positive electrode plates 2 and negative electrode plates 3 with a separator 4 interposed therebetween.

  The positive electrode grid of the positive electrode plate 2 is provided with ears 22, and the positive electrode plate 2 is connected to the positive electrode connection member 10 via the ears 22. The positive electrode connection member 10 includes a positive electrode shelf 6 connected to the ears 22 of the positive electrode lattice, and a positive electrode connector 8 or a positive electrode column provided on the positive electrode shelf 6. Similarly, the negative electrode lattice of the negative electrode plate 3 is provided with ears 32, and the negative electrode plate 3 is connected to the negative electrode connection member 9 via the ears 32. The negative electrode connection member 9 includes a negative electrode shelf 5 connected to the ear 32 of the negative electrode lattice, and a negative electrode column 7 or a negative electrode connector provided on the negative electrode shelf 5. In the illustrated example, a positive electrode connector 8 is connected to the positive electrode shelf 6 at one end of the battery case 12, and a negative electrode column 7 is connected to the negative electrode shelf 5. At the other end of the battery case 12, a positive pole is connected to the positive electrode shelf 6, and a negative electrode connector is connected to the negative electrode shelf 5.

In each cell, the whole of the positive electrode shelf, the negative electrode shelf, and the electrode plate group is immersed in the electrolyte.
A lid 15 provided with a positive terminal 16 and a negative terminal 17 is attached to the opening of the battery case 12. The positive electrode connection body 8 is connected to a negative electrode connection body connected to the negative electrode shelf of the electrode plate group 11 in the adjacent cell chamber 14 through a through hole provided in the partition wall 13. Thereby, the electrode plate group 11 is connected in series with the electrode plate group 11 in the adjacent cell chamber 14. At one end of the battery case 12, the negative pole 7 is connected to the negative terminal 17, and at the other end, the positive pole is connected to the positive terminal 16. An exhaust plug 18 having an exhaust port for discharging gas generated inside the battery to the outside of the battery is attached to the liquid injection port provided in the lid 15.

  The positive electrode plate 2 includes a positive electrode lattice 21 having ears 22 and a positive electrode active material layer (or positive electrode mixture layer) 24 held by the positive electrode lattice 21. The positive grid 21 is an expanded grid composed of an expanded mesh 25 that holds the positive active material layer 24, a frame bone 23 provided at the upper end of the expanded mesh 25, and ears 22 connected to the frame bone 23.

  Similarly, the negative electrode plate 3 includes a negative electrode lattice 31 having ears 32 and a negative electrode active material layer (or negative electrode mixture layer) 34 held by the negative electrode lattice 31. The negative electrode lattice 31 is an expanded lattice composed of an expanded mesh 35 that holds the negative electrode active material layer 34, a frame bone 33 provided at the upper end of the expanded mesh 35, and an ear 32 connected to the frame bone 33.

  The positive electrode connection member 10 can be formed of lead or a lead alloy exemplified as the material of the positive electrode lattice. The negative electrode connection member 9 can be formed of lead or a lead alloy exemplified as the material of the negative electrode lattice.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
(1) Production of positive electrode plate A positive electrode plate 2 shown in FIG. 2 was produced by the following procedure.
The raw material lead oxide powder, water and dilute sulfuric acid (specific gravity 1.40 g / cm ³ ) were mixed at a mass ratio of 100: 15: 5 to obtain a positive electrode paste.

  A base material sheet made of a Pb-0.06 mass% Ca-1.6 mass% Sn alloy obtained by a casting method and a lead alloy foil containing Sb were stacked and rolled. Thereby, the lead alloy foil was pressure-bonded on the base material sheet, and a composite sheet having a lead alloy layer containing Sb having a thickness of 20 μm on one surface of the base material layer having a thickness of 1.1 mm was obtained. The part where the lead alloy foil is pressure-bonded to the base material sheet is only the part that forms the expanded mesh in the later-described expanding process, and the center part of the base material sheet that forms the ears 22 of the positive grid and the frame bone 23 is lead. The alloy foil was not crimped.

  After forming a predetermined slit in the composite sheet, this slit was developed to form an expanded mesh 25 to obtain an expanded lattice (expanding process). In addition, since the center part of the composite sheet was used for the part which forms the ear | edge 22 of the positive electrode grid | lattice and frame frame 23 which are mentioned later, it was not expanded.

  The expanded mesh 25 was filled with a positive electrode paste and cut into an electrode plate shape having positive electrode lattice ears 22. This was aged and dried to obtain a non-chemically formed positive electrode plate (length: 115 mm, width: 137.5 mm). And the positive electrode plate 2 by which the positive electrode active material layer 24 was hold | maintained at the positive electrode grid 21 was obtained by forming in a battery case mentioned later.

(2) Production of Negative Electrode Plate A negative electrode plate 3 shown in FIG. 3 was produced by the following procedure.
A negative electrode mixture paste was obtained by mixing raw material lead powder (negative electrode active material), metatitanic acid, water, dilute sulfuric acid (specific gravity 1.40 g / cm ³ ), an anti-shrink agent, and a conductive material (carbon black). The amounts of water, dilute sulfuric acid, anti-shrink agent, and conductive material were 12 parts by mass, 7.0 parts by mass, 1.0 part by mass, and 0.1 parts by mass, respectively, with respect to 100 parts by mass of the negative electrode active material. . Metatitanic acid was used in such an amount that the amount of titanium (titanium atoms) relative to 100 parts by mass of the raw material lead powder (negative electrode active material) was the value shown in Table 1. As the anti-shrink agent, lignin and barium sulfate were used at a mass ratio of 1: 9.

  A base material sheet made of a Pb-0.07 mass% Ca-0.25 mass% Sn alloy obtained by a casting method is rolled to a thickness of 0.7 mm, and the base material sheet is expanded by the same method as described above. did. The expanded mesh was filled with a negative electrode mixture paste, and an unformed negative electrode plate (length: 115 mm, width 137.5 mm) was obtained by the same method as described above. And the negative electrode plate 3 by which the negative electrode active material layer 34 was hold | maintained at the negative electrode lattice 31 was obtained by forming in the battery case mentioned later.

(3) Production of lead acid battery A lead acid battery 1 as shown in FIG. 1 was produced according to the following procedure.
By laminating the single negative electrode plate 3 obtained above with the separator 4 (1.0 mm thick glass fiber mat) sandwiched between the two positive electrode plates 2, the electrode plate group 11 is formed. Obtained. At this time, the separator 4 was folded in two and disposed so as to sandwich the negative electrode plate therebetween.

  Next, the ears 22 and 32 were collectively welded to form the positive electrode shelf 6 and the negative electrode shelf 5. The electrode plate group 11 is housed one by one in each of the six cell chambers 14 partitioned by the partition wall 13 of the battery case 12, and the positive electrode connection body 8 connected to the positive electrode shelf 6 is connected to the negative electrode of the adjacent electrode plate group. Adjacent electrode plate groups were connected in series by connecting to the negative electrode connector continuously provided on the shelf. In this example, the connection between the electrode plate groups was made through a through hole (not shown) provided in the partition wall 13. A Pb-2.5 mass% Sn alloy was used for the positive electrode connector and the negative electrode connector.

A positive electrode column was provided on one positive electrode shelf of the electrode plate group housed in the cell chambers 14 at both ends, and a negative electrode column 7 was provided on the other negative electrode shelf 5. The lid 15 was attached to the opening of the battery case 12, and the positive electrode terminal 16 and the negative electrode terminal 17 provided on the lid 15 were welded to the positive electrode column and the negative electrode column 7. Thereafter, a predetermined amount of electrolyte (sulfuric acid aqueous solution, specific gravity 1.20 g / cm ³ ) was injected from the injection port provided in the lid 15, and chemical conversion was performed in the battery case. In addition, after the chemical conversion, the entire electrode plate group 11, the positive electrode shelf 6, and the negative electrode shelf 5 were immersed in the electrolyte. After the formation, the electrolyte in the battery was taken out, and a sulfuric acid aqueous solution was newly injected to adjust the final specific gravity to 1.28 g / cm ³ . Next, an exhaust plug 18 having an exhaust port for discharging gas generated inside the battery to the outside of the battery was attached to the injection port, and a 55D23 type (12V-48Ah) lead storage battery 1 defined in JIS D5301 was produced. .

(4) Evaluation A test cell was prepared by the following procedure (a). The following (b) and (c) were evaluated using the produced test cell.
(A) Production of test cell The positive electrode plate and the negative electrode plate produced in the above (1) and (2) were each cut into a size of 60 mm in length and 40 mm in width, and one negative electrode plate and two positive electrode plates were obtained. Got ready. An electrode plate group was formed by laminating a negative electrode plate in a state of being sandwiched between two positive electrode plates via a separator (a polyethylene microporous membrane, a base thickness of 0.2 mm, a width of 44 mm). At this time, the separator 4 was disposed so as to sandwich the negative electrode plate while being folded in half.

The obtained electrode plate group was sandwiched between acrylic plates from both sides and fixed. Next, a lead bar was welded to each of the negative electrode plate and the two positive electrode plates to form a negative electrode terminal and a positive electrode terminal, respectively. It was put into a polypropylene container, and a predetermined amount of a sulfuric acid aqueous solution having a specific gravity of 1.20 g / cm ³ was injected for chemical conversion. The sulfuric acid aqueous solution in the cell used for chemical conversion was removed, and a sulfuric acid aqueous solution having a predetermined composition described below was newly injected. In this way, a test cell (1.25 Ah, 2 V) was produced. As the electrolyte, the same one as used in (3) was used.

(B) Titanium ion concentration in the electrolyte A predetermined amount of the electrolyte solution was collected from the battery at 20 ° C., diluted, and the amount of titanium was quantified by ICP emission spectroscopic analysis. The titanium ion concentration in the electrolyte (mmol / L) Asked.

(C) IS cycle life First, the SOC of the test cell after chemical conversion was adjusted under the following conditions.
Charging (SOC adjustment): constant current, 0.2C, 7.5 hours Pause: 30 minutes Discharge (SOC adjustment): constant current, 0.2C, 30 minutes Pause: 12 hours Temperature: 25 ° C

Next, based on the idling stop life test (SBA S0101), charging and discharging were repeated under the following conditions until either the negative electrode or the positive electrode deteriorated.
Charge (IS): constant current (2.25C) -constant voltage (2.4V, maximum current 2.25C), 0.1 hour Discharge (IS): constant current, 1.0C, 0.1 hour Temperature: 25 ℃

Examples 2-3
Example 1 (2) is the same as Example 1 except that the addition amount of metatitanic acid was changed so that the amount of titanium relative to 100 parts by mass of the raw material lead powder (negative electrode active material) became the value shown in Table 1. Thus, a negative electrode plate and a lead storage battery were produced. And evaluation similar to Example 1 was performed.

Comparative Example 1
In Example 1 (2), a negative electrode plate and a lead storage battery were produced in the same manner as in Example 1 except that metatitanic acid was not added. And evaluation similar to Example 1 was performed.

Comparative Example 2
In Example 2, a negative electrode plate and a lead storage battery were produced in the same manner as in Example 2 except that titanium dioxide (rutile TiO ₂ ) was used instead of metatitanic acid. And evaluation similar to Example 1 was performed. In addition, the solubility with respect to the sulfuric acid aqueous solution (specific gravity 1.28) of the titanium dioxide in 20 degreeC is 0.009 mmol / L.

Comparative Example 3
A metatitanic acid powder (manufactured by Kishida Chemical Co., Ltd.) was added to an aqueous sulfuric acid solution (specific gravity 1.28 g / cm ³ ), and the mixture was allowed to stand after stirring and used as an electrolyte. At this time, metatitanic acid was added in an amount such that the titanium ion concentration in the electrolyte was 1.1 mmol / L. A lead-acid battery was prepared and evaluated in the same manner as in Comparative Example 1 except that the obtained electrolyte was used.

  The results of Examples and Comparative Examples are shown in Table 1. In addition, about IS cycle life, when the charge / discharge cycle number of the comparative example 1 was set to 100, it represented with the cycle number (cycle number ratio) of each example. Examples 1 to 3 were designated as A1 to A3, and Comparative Examples 1 to 3 were designated as B1 to B3. The amount of Ti in the negative electrode is the mass part of Ti with respect to 100 mass parts of the negative electrode active material.

  As shown in Table 1, compared to Comparative Example 1 in which the negative electrode does not contain a titanium compound, in the example in which the negative electrode contains a titanium compound (metatitanic acid) having a specific solubility in an aqueous sulfuric acid solution, the IS cycle life is Improved by more than 20%. Comparative Example 2 containing titanium dioxide having low solubility in an aqueous sulfuric acid solution had a low titanium ion concentration in the electrolyte and exhibited the same IS cycle life as Comparative Example 1 in which no titanium compound was used. In Comparative Example 3 in which the negative electrode did not contain a titanium compound and metatitanic acid was added to the electrolyte, the titanium ion concentration in the electrolyte was 1.1 mmol / L, which is considerably higher than that in the example, but the IS cycle life was in the example. And less than half of the other comparative examples.

  The charging / discharging conditions in the measurement of the IS cycle life are conditions in which the deterioration of the negative electrode is likely to proceed. In Examples 1 to 3 and Comparative Examples 1 and 2, the deterioration of the negative electrode has proceeded first. In these examples, the negative electrode was deteriorated at the stage where charging / discharging could not be repeated. On the other hand, in Comparative Example 3, the positive electrode was deteriorated at the stage where charging / discharging could not be repeated.

  In the examples, the results were shown in the case where the electrolyte was replaced after chemical conversion and the specific gravity of the electrolyte was adjusted. In this case, the effect of the present invention is obtained by the action of titanium ions dissolved from the negative electrode after replacing the electrolyte. However, the same effect as described above can be obtained not only in such a case but also when the specific gravity of the electrolyte is adjusted after the formation. The specific gravity of the electrolyte after chemical conversion can be adjusted, for example, by adding a sulfuric acid aqueous solution having a higher specific gravity to the electrolyte. In this case, the effect is obtained by the action of titanium ions dissolved from the negative electrode during chemical conversion in addition to titanium ions dissolved from the negative electrode after chemical conversion. In addition, the same effect as described above can be obtained by a method of adjusting the specific gravity of the electrolyte after chemical conversion in consideration of sulfate ions released from the positive electrode and the negative electrode during chemical conversion and electrolyte decrease during charging. In this case, it is not necessary to replace or add the electrolyte. Further, the same effect as described above can be obtained by using titanium ions dissolved in advance in the electrolyte at the time of chemical conversion or the electrolyte at the time of replacement.

  The lead acid battery which concerns on one Embodiment of this invention has the outstanding charge acceptance property and IS life characteristic in the use mode which repeats charging / discharging in a halfway charge state. Therefore, it is suitably used for a vehicle equipped with an idle stop system or a regenerative brake system.

  DESCRIPTION OF SYMBOLS 1 Lead acid battery, 2 Positive electrode plate, 3 Negative electrode plate, 4 Separator, 5 Negative electrode shelf, 6 Positive electrode shelf, 7 Negative electrode pillar, 8 Positive electrode connection body, 9 Negative electrode connection member, 10 Positive electrode connection member, 11 Electrode plate group, 12 Battery case 13 partition, 14 cell chamber, 15 lid, 16 positive terminal, 17 negative terminal, 18 exhaust plug, 21 positive grid, 22, 32 ear, 23,33 frame bone, 24 positive active material layer, 25, 35 expanded mesh, 31 Negative electrode lattice, 34 Negative electrode active material layer

Claims (4)

A lead-acid battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte containing sulfuric acid,
The negative electrode includes a titanium compound,
The said titanium compound is a lead acid battery whose solubility in 20 degreeC with respect to the sulfuric acid aqueous solution whose specific gravity in 20 degreeC is 1.28 is 0.01 mmol / L or more.   The lead acid battery according to claim 1, wherein in the negative electrode, the content of titanium with respect to 100 parts by mass of the negative electrode active material is 0.001 to 0.05 parts by mass.   The lead acid battery according to claim 1 or 2, wherein the titanium compound is at least one selected from the group consisting of metatitanic acid or a salt thereof, titanyl sulfate, and titanium sulfate. The electrolyte includes titanium ions,
The lead acid battery according to any one of claims 1 to 3, wherein a concentration of the titanium ions in the electrolyte is 0.005 mmol / L or more and less than 1 mmol / L.

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