JP4953600B2 - Lead acid battery - Google Patents

Description

  The present invention relates to a lead-acid battery, particularly a lead-acid battery having improved life performance due to corrosion of a positive grid and sulfation of a negative electrode when used in a PSOC state (partially charged state) among life extension technologies of lead-acid batteries for automobiles. Is.

Traditionally, lead-acid batteries for automobiles, called SLI batteries, have been used as a power source for motors that are installed in more than 100 high-end cars, including starter start-up, lighting, and ignition. Since the engine drives the generator to supply electric power except for starting the starter at that time, the lead-acid battery was not discharged so deeply. Moreover, since charging from a generator often places the battery in a fully charged state, it has been required to be resistant to overcharging.

On the other hand, in recent years, there has been a strong demand for improvement in fuel consumption and reduction of exhaust gas in automobiles, and the use conditions of lead storage batteries have changed greatly. One of them is an idling stop that stops the engine while the vehicle is stopped by a signal or the like. Since the power supply from the generator is also stopped when the engine is stopped, the electric power during this period is covered by the discharge of the lead storage battery, and is deeply discharged as compared with the conventional case. The other is the control of lead battery overcharge. This is to reduce the waste of energy used for charging the lead-acid battery as much as possible. When the charging efficiency is low, the lead-acid battery is used in an insufficiently charged state.

As a result, under conventional usage conditions, lead-acid batteries have reached the end of their lives due to positive grid gloss and positive grid corrosion, shrinkage of the negative electrode active material due to high temperatures in the engine room, and decrease in electrolyte due to high temperature and overcharge, etc. Under the usage conditions such as idle stop and overcharge control, lead-acid batteries were placed in deep charge / discharge and chronic undercharge condition, and positive and negative electrode active materials caused sulfation. In particular, the negative electrode sulfation progressed rapidly and the lifetime was remarkably short.

At the same time, significant corrosion of the upper part of the positive electrode grid (hereinafter, the upper part and the upper half of the positive electrode grid is the case where the ear part is attached) is observed, especially in the vicinity of the upper half of the positive electrode grid. It was confirmed. This is presumably because the negative sulfation progresses gradually from the lower part of the electrode plate where it is difficult to be charged to the upper part because the undercharge state continues, and the current distribution of the positive electrode facing it is also concentrated on the upper part. At the same time, the positive electrode is unlikely to form a corrosion-resistant conductive oxide film (for example, α-PbO2) on the lattice surface at a potential corresponding to an undercharged state, and the entire surface corrosion accompanied by the formation of lead sulfate with low conductivity proceeds. It is considered that the discharge reaction is concentrated on the upper portion of the electrode plate, that is, the portion where the potential difference is small and easy to use. As a result, the corrosion rate of the upper half of the positive electrode lattice reaches about 50% even during the period of use of about half of the conventional one, reaching the corrosion rate equivalent to the conventional end of life, while the corrosion rate of the lower half of the positive electrode lattice is only about 20%. . Conventionally, if the corrosion rate of the lower half of the lattice is 20%, the upper half of the lattice is similar. In order to solve this problem, it is conceivable to increase the mass of the upper half of the lattice from the viewpoint of securing conductivity against the thinning of the lattice. However, if estimated from the above corrosion rate and the period of use, the upper half of the lattice is 1. Since the mass of 6 times or more is required, and it is difficult to secure an active material space, it is difficult to prevent corrosion at the upper part of the positive electrode grid and ensure the life.

In addition, the continuous reaction at the top of the positive grid makes it easier for the positive electrode active material to soften and drop off, accelerating the corrosion of the positive frame grid (including vertical and horizontal frame bones) exposed by softening and dropping. To do. As a result, the positive electrode falls into a vicious circle in which the charging efficiency further decreases. In addition, the automobile side has been improved to support idle stop, and the engine can be restarted with less power than before. As a result, the engine can be started even if positive grid corrosion or positive and negative sulfation progresses considerably. As a result, the phenomenon that the engine cannot be started after the occurrence of the cracking phenomenon as in the conventional case does not appear, and the battery suddenly dies that the engine cannot be started suddenly.

As means for improving the positive electrode lattice, the lead amount in the upper third is increased (Patent Document 1), the electrode plate is divided into four parts, and the lead amount closest to the ear is increased (Patent Document 2). ing.

JP-A-5-234595 Japanese Utility Model Publication No. 54-56130

However, the methods described in Patent Documents 1 and 2 are mainly for the purpose of suppressing lattice gloss during overcharging, and do not improve positive and negative electrode sulfation and positive electrode lattice corrosion under idling stop and charge control conditions. Absent. In other words, the inventors thought that if the performance of both the conventional use and the idle stop use cannot be improved, it is not possible to cope with the current automobile in which those systems are mixed.

Against this backdrop, the positive and negative electrode sulfation and the positive electrode lattice corrosion under idling stop and charge control conditions are improved, and it is possible to cope with the performance of both conventional SLI applications and idle stop applications. It would be desirable to provide a lead-acid battery that operates in an automated manner.

In the present invention, the mass ratio of the upper half with respect to the lower half of the positive electrode lattice is 1.1 to 1.5, and the electrolytic solution has Al ions of 0.01 mol / l to 0.30 mol / l and Se ions of 0.0002 mol. The value obtained by measuring the density of the positive electrode active material by the water displacement method is 3.8 g / cc or more, containing at least one kind of Ti ions from 0.001 mol / l to 0.1 mol / l. It is 4.5 g / cc , and the electrolyte solution has a specific gravity of 1.260 to 1.320 (20 ° C.) .

In the present invention, the mass ratio of the upper half with respect to the lower half of the positive electrode lattice is 1.1 to 1.5, so that the conductivity is increased and the potential difference is reduced, and the thinning of the lattice due to the corrosion concentrated on the upper portion of the lattice is reduced. be able to. However, an increase in the mass on the half of the lattice alone does not provide a fundamental solution, and it is necessary to suppress negative electrode sulfation due to insufficient charging. Conventional batteries easily suffered from insufficient charging when idle stop or overcharge control was performed, causing sulfation. Therefore, in the present invention, in addition to specifying the mass ratio, the charging efficiency of the negative electrode is increased by adding at least one of Al ions, Se ions, and Ti ions to the electrolytic solution, thereby solving this problem. The reason is not clear, but by adding Al ions, Se ions, and Ti ions to the electrolyte, crystal growth and coarsening of lead sulfate produced in the negative electrode when the discharge state is continued is suppressed, and fine crystals While maintaining the state, irregularities are formed on the crystal surface. That is, the produced lead sulfate has high reactivity, and charging efficiency is improved and sulfation is difficult to occur. As a result, corrosion of the upper part of the positive electrode lattice is suppressed, and the mass ratio is suppressed to a range of 1.1 to 1.5. Even the required life can be ensured.

Further, preferable addition amounts to the electrolytic solution are Al ions of 0.01 mol / l to 0.30 mol / l, Se ions of 0.0002 mol / l to 0.0012 mol / l, Ti ions of 0.001 mol / l to 0.1 mol. It is possible to provide a long-life storage battery by setting this range.

In addition, the positive electrode active material density has a value measured by a water displacement method of 3.8 g / cc or more from the viewpoint of suppressing active material dropping due to softening due to physical bonding of the active material and suppressing corrosion due to exposure of the positive electrode lattice. 4.5 g / cc is preferred. If it is less than 3.8 g / cc, the positive electrode active material density is low and softening tends to proceed. If it exceeds 4.5 g / cc, the positive electrode active material density is too high, the utilization rate is lowered, and the capacity cannot be secured.
The water displacement method is a method of measuring the mass of the positive electrode substrate, the dry mass of the packed substrate, the mass in water, and the lifting mass, and obtaining the positive electrode active material density from the equation (1).
(Formula 1)

The specific gravity of the electrolyte is preferably 1.260 to 1.320 (20 ° C.) in order to maintain high charging efficiency. If it is smaller than 1.260, the capacity cannot be secured because the sulfuric acid content is small. When it is larger than 1.320, the oxygen overvoltage of the positive electrode is lowered, so that charging efficiency is impaired.

The present invention improves the positive and negative electrode sulfation and the positive electrode lattice corrosion under idling stop and charge control conditions, and can be used for both conventional and idle stop applications. It is possible to provide storage batteries, and transportation equipment such as automobiles that consume a large amount of fossil fuel consumption, especially the use of new energy such as energy saving and natural energy, which are inevitably required due to global environmental problems that will become increasingly important in the 21st century. There is something that responds to the improvement in fuel economy, and its industrial value is great.

The positive electrode grid used in the present invention is made of a lead-calcium alloy, and is manufactured by making the mold vertical and pouring molten lead at a constant speed from above (hereinafter, the positive grid manufactured in this way is called a gravity cast grid. ), The portion to which the ear is attached is the top, and the mass ratio of the upper half frame lattice to the lower half is 1.1 to 1.5. In order to change the mass ratio of the frame lattice to 1.1 to 1.5, increase the number of horizontal or / and vertical frame bones in the upper half from the lower half, or increase the thickness of the frame lattice and vertical / horizontal frame bones. It is possible to make it thicker than the lower half. With such a structure, the conductivity is increased, the potential difference is reduced, and lattice thinning due to corrosion concentrated on the upper portion of the lattice can be reduced.

In the lead storage battery of the present invention, an active material paste is prepared by kneading lead powder with water or sulfuric acid, and the positive electrode is applied by filling the active material paste on different substrates in which the weight ratio of the frame lattice is different between the upper half and the lower half. Aging is performed to produce a negative electrode unformed plate and a positive electrode unformed plate. A plurality of the positive and negative electrode plates obtained are alternately laminated via separators to produce an electrode plate group. The electrode plate group is housed in the battery case, and the battery case is covered with a predetermined amount. An electrolytic solution was injected to prepare a lead storage battery. At this time, the thickness of the electrode plate group and the dimensions in the battery case are adjusted so that a predetermined pressure, for example, a pressure (group pressure) of about 20 to 30 kpa is applied by the battery case, and the electrode plate group housed in the battery case The thickness of the separator was adjusted so that the distance between the positive electrode plate and the negative electrode plate was a predetermined distance, and the lid was covered by heat sealing. In addition, a predetermined amount of Al ions was added as a sulfate during injection of the electrolyte.

In the present invention, an example in which a sulfate of Al ion is added alone to the electrolytic solution has been shown. However, oxides, hydroxides, borates, aluminates, selenates, titanates, sulfites. Salts, phosphates, carbonates, etc. can also be added to the electrolyte. Further, two or more kinds may be mixed and added to the electrolytic solution.
In addition, although the positive electrode lattice is an example of a gravity cast lattice, the same effect can be obtained even if a continuous casting, rolling, an expanded lattice processed by an extruded strip, or a punched lattice is used. Furthermore, although the example of the liquid battery is shown here, it goes without saying that the present invention can also be applied to a sealed battery.

(Manufacture of unformed negative electrode plate)
In the present invention, acetylene black having a specific surface area of 70 m ² / g and barium sulfate powder were added to the lead oxide produced by the ball mill method and dry-mixed. Lignin was added thereto as an aqueous solution, followed by kneading while adding ion-exchanged water to prepare a water paste, and further kneading while adding dilute sulfuric acid having a specific gravity of 1.360 (20 ° C.) to obtain a negative electrode active material paste. The amount of ion-exchanged water used at this time was about 10 parts by weight with respect to 100 parts by weight of lead oxide, and the amount of dilute sulfuric acid was 10 parts by weight. The amount of ion-exchanged water was adjusted so that the cup density of the completed negative electrode active material paste was about 140 g / 2 in ³ . The negative electrode active material paste thus produced was filled into a cast substrate, aged for 24 hours in an atmosphere of 40 ° C. and 95% humidity, and then dried to obtain a negative electrode unformed sheet.
(Manufacture of unformed positive electrode plate)
Next, as with the negative electrode plate, 100 parts by weight of lead oxide produced by the ball mill method was kneaded while adding 10 parts by weight of ion-exchanged water and then 10 parts by weight of dilute sulfuric acid having a specific gravity of 1.270 (20 ° C.), and A material paste was obtained. In addition, the amount of ion-exchanged water is adjusted so that the cup density of the finished positive electrode active material paste is about 130 g / 2 in ³ (about 4.2 g / cc when the dry positive electrode active material density is measured by the water displacement method). It was adjusted. The positive electrode active material paste produced in this way is filled into a cast substrate made of a lead-calcium alloy in which the number of the upper half horizontal and / or vertical frame bones is increased from the lower half and the mass ratio of the frame lattice is changed, and the negative electrode plate Aged in the same manner as above and then dried to obtain a positive electrode unformed sheet.
(Battery assembly, electrolyte preparation and formation)
Then, these positive electrode unformed plates and negative electrode unformed plates were alternately laminated and combined with polyethylene separators, and the electrode plates were welded together by a COS method (cast on strap method) to form an electrode plate group. This was put into a battery case made of PP (made of polypropylene) and covered by heat sealing. Then, as shown in Table 1, the amount of Al ions to be injected into the electrolyte solution is changed and added in various ways, and the battery is formed to form a D23 size 12V lead acid battery with a 5-hour rate capacity of 50 Ah. did. In addition, the electrolyte solution specific gravity after battery case formation was 1.280 (20 degreeC).
(Idle stop life test)
Each of the above prototypes was manufactured by changing the mass ratio of the frame grid (hereinafter referred to as the positive grid weight ratio) in various ways by increasing the number of horizontal or / and vertical frame bones in the upper half of the positive grid as described in Table 1 from the lower half. The lead storage battery was fully charged at 25 ° C. for 5 hours with a current. Next, an idle stop life test is performed in which a combination of constant current discharge at 40 ° C. for 50 seconds for 59 seconds and 300 A for 1 second and constant current / constant voltage charging for 100 A for 60 seconds for an upper limit voltage of 14.0 V is one cycle. The number of cycles to life was measured. In addition, the battery for which the life test was completed was disassembled, the state of the positive electrode grid was observed, and the cause of the life was investigated. Table 1 shows the results of the cycle life and the cause of the life. In addition, the lifetime judgment was made into the lifetime when the discharge voltage of 300 A and 1 second fell below 7.2V.

As shown in Table 1, the positive electrode lattice weight ratio was 1.1 to 1.5, and the electrolyte contained Al ions and Se.
By adding at least one of ions and Ti ions, it is possible to improve the cycle life and provide a long-life storage battery. The amount of the electrolyte added includes Al ions and Se.
Ion and Ti ion are 0.01 mol / l to 0.30 mol / l, 0.0002 mol / l to 0.0012 mol / l, 0.001 mol / l to 0.1 mol / l, respectively, It is possible to provide a long-life storage battery exceeding 000 cycles. In the case where Al ions or the like were not added to the electrolytic solution, no improvement in cycle life was observed even if the positive electrode lattice weight ratio was changed to any ratio of 1.0 to 1.6. Further, when the positive electrode lattice weight ratio is smaller than 1.1 or larger than 1.5, the cycle life is improved as compared with the case where Al ions are not added to the electrolytic solution, but the positive electrode lattice weight ratio is 1.1. There were no more than 30,000 cycles, such as ~ 1.5.

Also, each lead-acid battery that had reached the end of its life was disassembled, the state of the positive electrode grid was observed, and the cause of the life was investigated. The main deterioration factor was due to softening of the positive electrode active material. When the lattice weight ratio is 1.1 to 1.5, the electrical conductivity increases and the potential difference decreases, and it is possible to alleviate lattice thinning due to corrosion concentrated on the upper portion of the lattice, and Al ions are added. As a result, it became difficult to cause sulfation, and as a result, it was confirmed that corrosion of the upper part of the positive electrode lattice was suppressed. The same result was obtained when two or more types of ions were added, for example, when Al ions and Se ions were added to the electrolyte. Similar results were obtained when Se ions and Ti ions were added to the electrolyte. When the positive electrode lattice weight ratio is less than 1.1, the life of the storage battery is reached due to corrosion of the upper portion of the lattice. Further, when the positive electrode lattice weight ratio is larger than 1.6, the lattice does not corrode, but the life of the storage battery is reached due to softening of the positive electrode active material and insufficient capacity. Further, in the case where Al ions, Se ions, or Ti ions are not added, the lead-acid battery has reached an early life due to corrosion and sulfation on the upper part of the lattice.

  As shown in Table 2, except that the density of the positive electrode active material after the formation of the battery case in Example 1 was 3.5, 3.8, 4.2, 4.5, and 4.8 g / cc, respectively, by the water displacement method. The positive electrode lattice weight ratio is 1.3, and the amount of added Al ions, Se ions, and Ti ions to be injected into the electrolytic solution is variously changed to form a battery case in the same manner as in Example 1, and the D23 size having a 5-hour rate capacity of 50 Ah. Each 12V lead acid battery was prototyped. Thereafter, an idle stop life test was performed, and the number of cycles until the life was measured. Table 2 shows the number of cycle lives at that time. The addition amounts of Al ions, Se ions, and Ti ions are as shown in Table 2, respectively.

As shown in Table 2, the positive electrode active material density in the range of 3.8 to 4.5 g / cc is particularly preferable for any of Al ions, Se ions, and Ti ions, and the physical bond suppresses the loss of the active material due to softening. From the viewpoint of suppressing corrosion due to exposure of the positive electrode grid, it is possible to improve the cycle life and provide a long-life storage battery. When the positive electrode active material density is less than 3.8 g / cc, softening progresses because the positive electrode active material density is low regardless of whether Al ions, Se ions, or Ti ions are added to the electrolyte. The cycle life is slightly reduced as compared with 3.8 to 4.5 g / cc. On the other hand, when the positive electrode active material density is greater than 4.5 g / cc, the positive electrode active material density is 3.8 to 4.5 g / cc when any of Al ion, Se ion, and Ti ion is added to the electrolytic solution. Compared with the above, the density of the positive electrode active material is too high, the utilization rate is reduced, and the battery life cannot be ensured, so the cycle life is slightly reduced.

Table 3 shows that the specific gravity (20 ° C.) of the sulfuric acid aqueous solution that is the electrolytic solution after the formation of the battery case in Example 1 was set to 1.220, 1.260, 1.280, 1.320, and 1.360, respectively. Thus, the positive electrode lattice weight ratio is 1.3, the positive electrode active material density is 4.2 g / cc by water substitution method, and the addition amount of Al ions, Se ions, and Ti ions injected into the electrolyte is variously changed. Similarly, a battery case was formed, and a D23 size 12V lead storage battery having a 5-hour rate capacity of 50 Ah was prototyped. An idle stop life test was performed in the same manner as in Example 1, and the number of cycles until the life was measured. Table 3 shows the cycle life number at that time. The addition amounts of Al ions, Se ions, and Ti ions are as shown in Table 3, respectively.

As shown in Table 3, charging efficiency can be kept high and the cycle life can be improved by setting the electrolyte specific gravity to 1.260 to 1.320 (20 ° C.) in any of Al ion, Se ion, and Ti ion. It is possible to provide a long-life storage battery. When the electrolyte specific gravity is greater than 1.320 (20 ° C.), the addition of Al ion, Se ion, or Ti ion to the electrolyte reduces the oxygen overvoltage of the positive electrode, thereby impairing charging efficiency. Compared to 1.260 to 1.320 (20 ° C.), the cycle life is slightly reduced.

Above, the mass ratio of the upper half relative to the lower half of the positive grid from the results of Examples 1-3 and from 1.1 to 1.5, and Al ions, Se ions in the electrolyte solution, see containing at least one Ti ions Al ions, Se ions, T added to the electrolyte
i The amount of ions added is 0.01 mol / l to 0.30 mol / l, 0.002 mol / l to 0.0012 mol / l, 0.001 mol / l to 0.1 mol / l, respectively, When the material density is 3.8 g / cc to 4.5 g / cc by the water substitution method and the specific gravity (20 ° C.) of the sulfuric acid aqueous solution as the electrolyte is 1.260 to 1.320, idling stop and charge control are performed. Improves positive and negative electrode sulfation and positive electrode lattice corrosion under certain conditions, and can be used for both conventional and idle stop applications. It also suppresses the loss of active material due to softening and suppresses corrosion due to positive electrode lattice exposure. It is possible to provide a lead-acid battery that can maintain high charging efficiency and that is economical and operates stably over a long period of time.

Claims (2)

The mass ratio of the upper half with respect to the lower half of the positive electrode lattice is 1.1 to 1.5, Al ions are 0.01 mol / l to 0.30 mol / l, and Se ions are 0.0002 mol / l to 0 in the electrolyte. .0012 mol / l, Ti ion containing at least one of 0.001 mol / l to 0.1 mol / l, and the positive electrode active material density measured by the water displacement method is 3.8 g / cc to 4.5 g / A lead-acid battery characterized by having a cc and an electrolyte specific gravity of 1.260 to 1.320 (20 ° C.) . The addition amounts of Al ions, Se ions, and Ti ions added to the electrolyte are 0.01 mol / l to 0.30 mol / l, 0.0002 mol / l to 0.0012 mol / l, and 0.001 mol / l to 0.001 mol, respectively. The lead acid battery according to claim 1, wherein the content is 1 mol / l.