JP2016072105A - Lead storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead storage battery in which the post-cycle worsening in charging acceptability of a negative electrode and cycle life (IS cycle life) is suppressed.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 lead storage battery includes a solid titanium compound disposed so as to be put in contact with the electrolyte; and 0.01 mmol/L or more of titanium ions is included in the electrolyte. The concentration of titanium ions in the electrolyte may be 3 mmol/L or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to lead-acid batteries, and particularly to improvements in electrolytes.

  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 discloses 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.

International Publication WO2007 / 036979 Pamphlet

  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 studies by the present inventors, when a predetermined concentration of titanium ions is added to the electrolyte, the effect of improving the charge acceptability in the initial state can be confirmed, but as the charge / discharge progresses, the charge acceptability and the cycle life are improved. It was found that the decrease could not be sufficiently suppressed. In particular, the charge acceptability of the negative electrode after repeated charge / discharge and the cycle life (idling stop (IS) cycle life) in an intermediate charge state such as an idle stop state are likely to decrease. This is considered to be because the titanium ion concentration in the electrolytic solution decreases with repeated charge and discharge, and the action on the negative electrode decreases.

  An object of the present invention is to suppress a decrease in charge acceptability and cycle life (IS cycle life) of a negative electrode after repeated charge and discharge in a lead storage battery.

  One aspect of the present invention is a lead storage 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, and the lead storage battery is in contact with the electrolyte. It is related with the lead acid battery which contains the solid titanium compound arrange | positioned in this way, and the said electrolyte contains 0.01 mmol / L or more of titanium ions.

  ADVANTAGE OF THE INVENTION According to this invention, even when the effect of the titanium ion contained in the electrolyte of a lead storage battery falls by charging / discharging, a titanium ion can be continuously supplied in an electrolyte from a titanium compound. Therefore, it can suppress that the charge acceptance property of the negative electrode in a charging / discharging cycle falls, and can suppress the fall of a cycle life (IS cycle life).

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. Here, the lead acid battery includes a solid titanium compound disposed so as to be in contact with the electrolyte, and 0.01 mmol / L or more of titanium ions is included in the electrolyte.

  It was found that when charging / discharging was repeated using an electrolytic solution in which titanium ions were simply dissolved, titanium ions decreased from the electrolyte due to the action on the negative electrode. On the other hand, a titanium compound that maintains a solid state in contact with an electrolyte has low solubility in the electrolyte (or sulfuric acid).

  In the above embodiment of the present invention, due to contact with the electrolyte, a part of the solid titanium compound is dissolved in the electrolyte as titanium ions so as to form a solution equilibrium state in the electrolyte. By utilizing such an action and disposing the solid titanium compound in the battery so as to come into contact with the electrolyte, when charging and discharging are repeated, titanium ions from the solid titanium compound continuously enter the electrolyte. It is replenished and the reduction | decrease of the titanium ion in electrolyte is suppressed. As a result, it can suppress that the charge acceptance of a negative electrode falls. Moreover, although the details are not clear, an effect of suppressing sulfation during overdischarge can be expected by causing titanium ions to continuously act on the negative electrode. Thereby, since the increase in the resistance of the negative electrode at the time of charging / discharging is suppressed, it is possible to suppress a decrease in cycle life, in particular, IS cycle life.

  The concentration of titanium ions in the electrolyte is, for example, 5 mmol / L or less, preferably 3 mmol / L or less or 1.5 mmol / L or less, and more preferably 1 mmol / L or less or less than 1 mmol / L. . The concentration of titanium ions in the electrolyte is 0.01 mmol / L or more, and may be 0.1 mmol / L or more. These upper limit value and lower limit value can be arbitrarily combined. The concentration of titanium ions in the electrolyte may be, for example, 0.01 to 5 mmol / L, 0.01 to 3 mmol / L, or 0.1 to 1.5 mmol / L.

When the concentration of titanium ions in the electrolyte is in the above range, even if the IS cycle is repeated, it is possible to further suppress a decrease in charge acceptability of the negative electrode. Moreover, the fall of the utilization factor of a negative electrode can be suppressed. If the titanium ion concentration is too high, the effect of improving the charge acceptance after the IS cycle is lowered, and the negative electrode utilization rate tends to be lowered.
The titanium ions contained in the electrolyte are mainly generated by dissolving the titanium compound, but may include those derived from additives and / or electrode components. The concentration of titanium ions in the electrolyte can be a value at 20 ° C., for example.

  The titanium compound may be disposed so as to be in contact with the electrolyte. For example, the titanium compound may be included in the positive electrode, the negative electrode, and / or the separator, but is included in the electrolyte (specifically, It is preferable to be immersed in the electrolyte.

  The amount of the titanium compound contained in the lead-acid battery is, for example, 0.02 g / Ah or more, 0.1 g / Ah or more, or 0.5 g / Ah or more per battery capacity at 0.2 C in terms of titanium atoms. Preferably there is. The amount of the titanium compound is preferably 10 g / Ah or less or 5 g / Ah or less, and more preferably 4 g / Ah or less or 2 g / Ah or less. These lower limit values and upper limit values can be arbitrarily combined. The amount of the titanium compound may be, for example, 0.1 to 10 g / Ah, 0.1 to 5 g / Ah, 0.1 to 4 g / Ah, or 0.5 to 2 g / Ah.

  The battery capacity at 0.2C was calculated based on the current amount of 1C obtained from the nominal capacity, and the rated charge / discharge was performed at the calculated current amount of 0.2C. Battery capacity. In the case of a test cell or the like, the battery capacity at 0.2 C may be obtained in the same manner as described above except that the theoretical capacity is adopted instead of the nominal capacity.

  When the amount of the titanium compound is in the above range, it is easy to ensure a sufficient IS cycle life. The amount of the titanium compound contained in the lead storage battery can be considered as the total amount of the solid titanium compound and the dissolved titanium ions. The amount of the titanium compound may be appropriately increased or decreased depending on the desired IS cycle life.

Titanium compounds include titanium-containing oxides, titanic acid hydrates (TiO ₂ .xH ₂ O (0 <x <1)), titanic acids (such as metatitanic acid (H ₂ TiO ₃ )), and / or titanium. Acid salts (such as metatitanates) can be used. The metatitanic acid salt, typically a metal salt (Li ₂ TiO _3, K ₂ alkali metal salts such as TiO _3; such as _{PbTiO 3, ZnTiO 3; MgTiO 3} , CaTiO 3, SrTiO alkaline earth metal salts such as _3); FeTiO ₃ , transition metal salts such as CoTiO ₃ and MnTiO ₃ can be exemplified. As the titanium compound, metatitanic acid, titanic acid hydrate and / or titanate are preferable, and among these, 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.

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. Regarding the specific gravity of the electrolyte in the battery, it is desirable that the specific gravity of the electrolyte in the fully charged battery is in the above range.

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.
(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 of the positive electrode grid include lead or a lead alloy. The lead alloy may include, for example, Ba, Ag, Ca, Al, Bi, Sb, and / or Sn. 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. When producing a positive electrode, you may use the lead powder containing lead oxide as a positive electrode active material.
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. When the positive electrode contains a titanium compound, a positive electrode mixture containing a positive electrode active material, a titanium compound, and other components as necessary may be used. The positive electrode may contain a known additive as required.

  The positive electrode can be formed by filling or applying a positive electrode paste (a paste containing a positive electrode active material or a positive electrode mixture paste) to a positive electrode grid and drying it to produce an unformed positive electrode, followed by chemical conversion treatment. The positive electrode paste contains sulfuric acid and / or water as a dispersion medium in addition to the components of the positive electrode active material or the positive 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.

(Negative electrode)
A 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 active material (or a negative electrode mixture) held by the negative electrode lattice. Since the negative electrode is generally plate-shaped, it is also called a negative electrode plate.

  Examples of the material for the negative electrode lattice include lead and lead alloys exemplified for the positive electrode lattice. 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.

Lead is used as the negative electrode active material. In producing the negative electrode, lead powder can be used, and the lead powder may contain lead oxide. The negative electrode mixture may include 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 containing a titanium compound can be produced using a negative electrode mixture containing a negative electrode active material, a titanium compound, and other components as required. Examples of lignin include synthetic lignin such as natural lignin and bisphenol sulfonic acid condensate.
The negative electrode may contain other known additives as necessary.
The negative electrode can be formed according to the case of the positive 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. The separator may further contain the titanium compound.

(Electrolytes)
The electrolyte includes sulfuric acid. In the embodiment of the present invention, since the solid titanium compound having a predetermined solubility with respect to the electrolyte is disposed in the battery so as to come into contact with the electrolyte, the titanium compound is dissolved in the electrolyte. As a result, the electrolyte in the battery contains titanium ions.
The concentration of titanium ions in the electrolyte is the type of titanium compound used, the physical properties of the titanium compound (surface area, particle size, etc.), and / or the form of the titanium compound, the specific gravity of the electrolyte (or the specific gravity of the aqueous sulfuric acid solution used in the electrolyte), etc. It can be adjusted by adjusting.

  The specific gravity of the electrolyte can be appropriately set within the range described above. The titanium compound is preferably used in a state immersed in an electrolyte, and an electrolyte prepared by dispersing titanium compound powder in an aqueous sulfuric acid solution may be used. Alternatively, a soluble titanium compound (such as dititanium sulfate) may be added in advance to sulfuric acid to dissolve a predetermined concentration of titanium ions, and then a solid titanium compound having low solubility may be added. In this case, the specific gravity (specific gravity at 20 ° C.) of the sulfuric acid aqueous solution before introducing the titanium compound may be set within the above range described as the specific gravity of the electrolyte. The form of the solid titanium compound to be added is not particularly limited, but may be powder, granule, pellet, or the like. Moreover, you may add the slurry-form thing which mixed the sulfuric acid and the titanium compound in a fixed ratio previously to the sulfuric acid which comprises electrolyte.

  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 powder (mixture of lead and lead oxide), 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.
Raw material lead powder, water, dilute sulfuric acid (specific gravity 1.40 g / cm ³ ), lignin and barium sulfate as a shrinkage preventive agent, and carbon black as a conductive material in a mass ratio of 100: 12: 7.0: 1.0: 0. By mixing at a ratio of 1, a negative electrode paste was obtained.

  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 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 was injected from the injection port provided in the lid 15 and chemical conversion was performed in the battery case. After the formation, 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 liquid injection port, and a 55D23 type (12V-48Ah) lead storage battery defined in JIS D5301 was produced. . 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.

As the electrolyte, a solution of metatitanic acid (manufactured by Kishida Chemical Co., Ltd.) added to sulfuric acid (aqueous sulfuric acid solution, specific gravity 1.28 g / cm ³ ), stirred, and allowed to stand was used as the electrolyte. The electrolyte was in a state containing solid metatitanic acid. The amount of metatitanic acid added was 3.9 g (40 mmol / L) with respect to 1 L of sulfuric acid. The amount of the titanium compound per 0.2 C capacity of the battery is 0.5 g / Ah in terms of titanium atoms.

(4) Evaluation A test cell was prepared by the following procedure (a). The following (b) and (c) were evaluated using the produced test cell. Note that 1.0 C of the test cell was calculated from the theoretical capacity of each test cell.

(A) Production of test cell The positive electrode plate and the negative electrode plate produced in the above (1) and (2) were cut into a size of 60 mm in length and 40 mm in width, respectively, and one negative electrode plate and two positive electrode plates were obtained. Got ready. The negative electrode plate was laminated in a state of being sandwiched between two positive electrode plates through a separator (polyethylene microporous film, base thickness 0.2 mm, width 44 mm) to form an electrode plate group. 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 sulfuric acid having a specific gravity of 1.20 g / cm ³ was injected to perform chemical conversion. The sulfuric acid in the cell used for chemical conversion was removed, and sulfuric acid 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. The amount of the titanium compound per 0.2 C capacity of the test cell is 0.5 g / Ah in terms of titanium atoms.
The concentration of titanium ions in the electrolyte was quantified by the following procedure. First, a predetermined amount of electrolyte was collected at 20 ° C., the solid titanium compound was removed by centrifugation, and the supernatant was filtered through a filter (pore diameter: 0.1 μm). The filtrate was collected, diluted, and the amount of titanium was quantified by ICP emission spectroscopy, and the titanium ion concentration of the electrolyte was determined to be 1.2 mmol / L.

(B) Charge acceptance (initial charge acceptance)
Under the following conditions, the SOC of the test cell after conversion was adjusted and charged. The charge acceptability was compared by the amount of electricity for 10 seconds after the start of charging.
Discharge (SOC adjustment): Constant current, 0.2C, 30 minutes Pause: 12 hours Charge (Charge acceptance): Constant current (3C)-Constant voltage (2.4V, maximum current 3C), 60 seconds Temperature: 25 ° C

(Charge acceptance after 360 cycles)
First, the SOC of the formed test cell 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), charge and discharge under the following conditions where the deterioration of the negative electrode is easy to accelerate were repeated 360 cycles.
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 ℃
And the charge acceptance property after 360 cycles was evaluated on condition of the following.
Charging (charge acceptance): constant current (3C) -constant voltage (2.4V, maximum current 3C), 60 seconds Temperature: 25 ° C

(C) Utilization rate of negative electrode active material About the test cell after chemical conversion, constant current discharge was carried out at 0.2 C to the final voltage 1.7V, and the cell capacity at this time was measured. Based on this cell capacity, the negative electrode active material capacity (mAh / g) was determined. The negative electrode active material utilization rate was expressed as a ratio of the negative electrode active material capacity (mAh / g) to the cell theoretical capacity, with 50% of the capacity of the negative electrode active material in each cell as the theoretical capacity of the cell.

Comparative Example 1
A test cell was prepared and evaluated in the same manner as in Example 1 except that sulfuric acid having a specific gravity of 1.28 g / cm ³ was used as the electrolyte.

Comparative Example 2
Instead of metatitanic acid, an electrolyte was prepared using titanium oxide (TiO ₂ , high-purity chemical). Titanium oxide was added in an amount of 3.2 g (equivalent to 40 mmol / L) to 1 L of sulfuric acid. In the electrolyte, titanium oxide was hardly dissolved and precipitated as a solid. A test cell was prepared and evaluated in the same manner as in Example 1 except that the obtained electrolyte was used. The concentration of titanium ions was quantified by the same procedure as in Example 1.

Comparative Example 3
Instead of metatitanic acid, to prepare an electrolyte using titanium sulfate (Ti (SO _{4) 2} hydrate, Mizuno manufactured sum Chemical). 0.33 g of titanium sulfate was added to 1 L of sulfuric acid. In the electrolyte, the titanium sulfate was completely dissolved. A test cell was prepared and evaluated in the same manner as in Example 1 except that the obtained electrolyte was used. The concentration of titanium ions was quantified by the same procedure as in Example 1.

Comparative Examples 4 and 5
3.3 g or 13.2 g of titanium sulfate hydrate was added to 1 L of sulfuric acid so that the amount of titanium sulfate per 1 L of electrolyte was the amount shown in Table 1 in terms of titanium atoms. Except for this, an electrolyte was prepared in the same manner as in Comparative Example 3. In the electrolyte, the added titanium sulfate was completely dissolved. A test cell was prepared and evaluated in the same manner as in Example 1 except that the obtained electrolyte was used. The concentration of titanium ions was quantified by the same procedure as in Example 1.

  The results of Examples and Comparative Examples are shown in Table 1. In addition, about charge acceptance, it represented with the ratio (charge acceptance ratio) when the initial stage electric current value of the comparative example 1 was set to 100%. About the negative electrode active material utilization factor, it represented with the ratio (negative electrode active material utilization factor ratio) when the negative electrode active material capacity | capacitance of the comparative example 1 was set to 100%. Example 1 was represented by A1, and Comparative Examples 1 to 5 were represented by B1 to B5. Table 1 shows the amount (in terms of titanium atom) of the titanium compound per 0.2 C capacity of the test cells of Comparative Examples 2 to 5.

  As shown in A1, B3 to B5 in Table 1, it can be seen that when a predetermined amount of titanium ions is included in the electrolyte, the initial charge acceptability is improved as compared with B1 and B2. After repeating charging and discharging, high charge acceptability was obtained in the example, whereas it was lower in the comparative example than in the example. It can be said that the high charge acceptability after the cycle suppresses the decrease in SOC and leads to the improvement of the IS cycle life.

  In the battery A1 of the example, the concentration of titanium ions in the electrolyte is the same as that of the battery B3 of the comparative example, but the charge acceptability after the cycle is high. Moreover, in A1, since the solid titanium compound was present in the battery in contact with the electrolyte, the decrease in the titanium ion concentration in the electrolyte during the cycle was suppressed. In A1, it is considered that the titanium ion is gradually dissolved from the solid titanium compound and continuously supplied to the electrolytic solution, thereby maintaining the action on the titanium ion negative electrode. Therefore, it can be seen that it is important that the solid titanium compound exists in the battery in contact with the electrolyte.

  In the batteries B4 and B5 of the comparative example, the negative electrode active material utilization rate is lower than that of the battery B3. Further, in the batteries B4 and B5, the effect of improving the charge acceptability corresponding to the high titanium ion concentration is not obtained. From the results of the batteries A1 and B3 to B5, the effect of improving the charge acceptance and IS cycle life is not obtained simply by increasing the amount of titanium ions dissolved, while ensuring a predetermined amount of titanium ion concentration, It can be seen that it is important to place the solid titanium compound in contact with the electrolyte in the battery.

In addition, the same test as the Example was performed by changing the specific gravity of sulfuric acid to 1.20 g / cm ³ , 1.24 g / cm ³ , 1.30 g / cm ³ , and 1.34 g / cm ³ . The titanium ion concentration in the electrolyte was 0.7 mmol / L, 0.8 mmol / L, 1.0 mmol / L, and 1.1 mmol / L, respectively. In the above test, substantially the same effect as in Example 1 was observed in charge acceptability and negative electrode utilization rate.

  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 (5)

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 lead acid battery includes a solid titanium compound disposed in contact with the electrolyte;
The lead acid battery in which the said electrolyte contains 0.01 mmol / L or more of titanium ions.   The lead acid battery according to claim 1, wherein the concentration of titanium ions in the electrolyte is 3 mmol / L or less. The titanium compound is immersed in the electrolyte,
The amount of the titanium compound contained in the said lead acid battery is a lead acid battery of Claim 1 or 2 which is 0.1 g / Ah or more per battery capacity in 0.2C of the said lead acid battery in conversion of a titanium atom.   The lead acid battery according to any one of claims 1 to 3, wherein the titanium compound is at least one selected from the group consisting of metatitanic acid, titanic acid hydrate, and metatitanate. The lead acid battery according to any one of claims 1 to 4, wherein the electrolyte has a specific gravity of 1.2 to 1.35 g / cm ³ .

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