JP5769096B2 - Lead acid battery - Google Patents

Description

  The present invention relates to a lead acid battery, for example, a car lead acid battery used in PSOC (Partial State of Charge).

  With the close-up of environmental issues, further improvements in fuel economy are being imposed on automobiles. As one solution to this problem, an increasing number of automobiles are equipped with a charge control function or idling stop function for lead-acid batteries. However, when the charge control function or idling stop function is installed, the lead-acid battery is charged for a short time, resulting in an undercharged state called PSOC, and the life is shortened. In particular, when the idling stop function is installed, cranking at the time of frequent engine restart and electric power of the electrical components during idling stop are all supplied from the lead storage battery, so that there is a tendency for the life to be remarkably shortened. This is because coarse crystals of lead sulfate that are difficult to reduce to metallic lead are likely to be generated in the negative electrode active material due to insufficient charging. This phenomenon is called sulfation.

  Patent Document 1 (JP2008-243493A) discloses that an electrolytic solution contains aluminum ions and a negative electrode active material contains carbon black in order to suppress sulfation. In Patent Document 1, a mixture of carbon black and activated carbon is further solidified into a wire shape with a binder such as styrene butadiene rubber and cut into an appropriate size (diameter 1 mm, length 1 mm, etc.), and the negative electrode active material 100 For example, mixing 5 parts by weight with respect to parts by weight is disclosed. Patent Document 2 (JP3936157B) discloses that 1 to 5 parts by weight of carbon is added to 100 parts by weight of the negative electrode active material, and Patent Document 3 (JP2003-36882A) discloses that 1 to 4 parts by weight of carbon is added to 100 parts by weight of the negative electrode active material. doing.

  Patent Document 4 (JP3835093B) discloses that 0.2 to 2% by mass of acetylene black and 0.05 to 0.2% by mass of graphite are added to the lead powder in the negative electrode paste of the sealed lead-acid battery. This is said to improve the utilization rate of the negative electrode active material.

JP2008-243493A JP3936157B JP2003-36882A JP3835093B

  The subject of this invention is providing the lead acid battery which is excellent in the lifetime performance in the motor vehicle equipped with the idling stop function, and has an initial stage discharge capacity in a practical range.

The present invention provides a lead plate comprising a positive electrode plate comprising a positive electrode grid and a positive electrode material, a negative electrode plate comprising a negative electrode lattice and a negative electrode material, and a dilute sulfuric acid electrolyte in which the electrode plate and the negative electrode plate are immersed. In storage battery,
The electrolyte contains 0.02 mol / L or more and 0.2 mol / L or less of aluminum ions,
The negative electrode material is 0.1 part by mass or more and 2 parts by mass or less of carbon black, 0.1 part by mass or more and 2 parts by mass or less of graphite, and 0.05 part by mass or more of fibrous carbon with respect to 100 parts by mass of the negative electrode active material. It is characterized by containing 1 part by mass or less. The electrolytic solution may or may not contain lithium ions, the lithium ion concentration in the electrolytic solution may be, for example, less than 0.02 mol / L, and the electrolytic solution may not contain lithium ions.

  Since the initial discharge capacity decreases as the total content increases, the carbon content is preferably 0.3 parts by mass or more and 5 parts by mass or less, more preferably 0.3 parts by mass with respect to 100 parts by mass of the negative electrode preformed active material. The amount is not less than 4 parts by mass and not more than 4 parts by mass, and since the effect is small if both carbon black, graphite, and fibrous carbon are in the vicinity of the lower limit, it is particularly preferably 1 part by mass to 4 parts by mass. When a part of metallic lead, which is a negative electrode active material, is oxidized to lead sulfate by the electrode reaction, the total amount of metallic lead is determined as a component such as lead contained in lead sulfate is reduced to metal.

  It is known that when aluminum ions are added to the electrolytic solution, growth of coarse and difficult-to-reduced lead sulfate crystals in the negative electrode active material is suppressed, and sulfation can be suppressed (for example, Patent Document 1). In addition, carbon black is also widely contained in the negative electrode active material (for example, Patent Document 1). However, carbon black flows out from the active material into the electrolytic solution in the process of producing lead sulfate or the like in the negative electrode active material. On the other hand, when fibrous carbon is added, a conductive path on the order of μm in the negative electrode active material is secured, and it becomes a carbon black carrier to suppress the outflow. Furthermore, as a foreign matter for lead sulfate, fibrous carbon hinders the crystal growth of lead sulfate. Graphite is a larger particle than fibrous carbon, and secures a conductive path to a portion that cannot be reached by fibrous carbon.

  Since carbon black, graphite, and fibrous carbon secure a conductive path around the lead sulfate crystal or the like, the lead sulfate is easily reduced during charging. This, combined with the suppression of lead sulfate crystal growth by aluminum ions, can suppress sulfation and improve the life performance of an automobile equipped with an idling stop function. However, the inventors have found that high rate discharge performance is reduced in a system containing carbon black, graphite and fibrous carbon, and aluminum ions. The inventor has found that the deterioration of the high-rate discharge performance can be eliminated by including 0.02 mol / L or more and 0.2 mol / L or less of lithium ions in the electrolytic solution.

  When the content of carbon black, graphite, or fibrous carbon is increased, there is a region in which the initial discharge capacity is lowered without improving the idling stop life performance. This region is over 2 parts by mass for carbon black and graphite and over 1 part by mass for fibrous carbon. From this, the upper limit of the content of carbon black, graphite, and fibrous carbon is determined as 2 parts by mass, 2 parts by mass, and 1 part by mass, respectively, with respect to 100 parts by mass of the negative electrode already formed active material.

  According to the present invention, the idling stop life performance of the lead storage battery can be improved and the initial discharge capacity can be kept within a practical range.

The negative electrode pre-formed active material has a graphite content of 0.5 parts by mass and a fibrous carbon content of 0.2 parts by mass, and the aluminum ion content and lithium ion content in the electrolyte solution are both 0.1 mol / L. Figure of characteristics when fixing and changing the carbon black content in the anode active material The carbon black content in the negative electrode active material is fixed at 0.5 parts by mass, the fibrous carbon content is fixed at 0.2 parts by mass, and both the aluminum ion content and lithium ion content in the electrolyte solution are 0.1 mol / L. Fig. 5 is a characteristic diagram when the graphite content in the anode active material is changed. Both the carbon black content and the graphite content in the negative electrode active material are fixed at 0.5 parts by mass, and the aluminum ion content and the lithium ion content in the electrolyte solution are both fixed at 0.1 mol / L. Figure of characteristics when changing the content of fibrous carbon in the chemical conversion material The carbon black content and graphite content in the negative electrode active material are fixed at 0.5 parts by mass, the fibrous carbon content is fixed at 0.2 parts by mass, and the lithium ion content in the electrolyte is fixed at 0.1 mol / L. Figure of characteristics when changing the aluminum ion content in the electrolyte The carbon black content and graphite content in the negative electrode active material are fixed at 0.5 parts by mass, the fibrous carbon content is fixed at 0.2 parts by mass, and the aluminum ion content in the electrolyte is fixed at 0.1 mol / L. Figure of characteristics when changing the lithium ion content in the electrolyte

  Hereinafter, an optimum embodiment of the present invention will be described. In carrying out the present invention, the embodiments can be appropriately changed within the scope of the claims in accordance with common sense and prior art of those skilled in the art.

Manufacture of lead-acid batteries
A 55B24 type lead-acid battery compliant with JIS D 5301 was manufactured. The nominal voltage is 12V, and the 5 hour rate rated capacity is 36Ah. As a positive electrode lattice material, a slab containing 0.07 parts by mass of Ca, 1.5 parts by mass of Sn, and unavoidable impurities, and the remainder being Pb was rolled into a sheet. Next, a positive electrode grid having a height of 115 mm, a width of 100 mm, and a thickness of 1.3 mm was produced by a rotary expanding method. The size, composition, and the like of the positive electrode lattice are arbitrary, and the positive electrode lattice may be produced by a reciprocal expanding method, a punching method, a book mold method, or the like instead of the rotary expanding method, and this also applies to the negative electrode lattice.

  As a negative electrode lattice, a slab containing 0.09 parts by mass of Ca, 0.35 parts by mass of Sn, and unavoidable impurities, with the balance being Pb, was rolled into a sheet. Next, a negative electrode grid having a height of 115 mm, a width of 100 mm, and a thickness of 1 mm was produced by a rotary expanding method.

  The positive electrode active material paste is 0.1 parts by weight of acrylic fiber that serves as a reinforcing material for 100 parts by weight of lead powder produced by the ball mill method, and kneaded with 13 parts by weight of water and 6 parts by weight of diluted sulfuric acid with a specific gravity of 1.40 at 20 ° C. It is a thing. The lead powder is not limited to the ball mill method, but may be a Barton method. The reinforcing material is not limited to acrylic fiber, and any reinforcing material may be added. Lead powder is a mixture of lead and lead oxide.

  The negative electrode active material paste is prepared by adding carbon black, graphite, and fibrous carbon to lead powder produced by a ball mill method so that the amount shown in Table 1 is 100 mass parts of the negative electrode pre-formed active material. 0.2 parts by mass, 0.6 parts by mass of barium sulfate and 0.1 parts by mass of acrylic fiber were added and kneaded with 11 parts by mass of water and 7 parts by mass of dilute sulfuric acid having a specific gravity of 1.40 at 20 ° C. The lead powder is not limited to the ball mill method, but may be a Barton method. The addition amount of lignin, barium sulfate, and acrylic fiber is arbitrary.

The carbon black used was acetylene black, the specific surface area when nitrogen gas was adsorbed by the BET method (hereinafter the same) was 70 m ² / g, and the average particle size measured by the centrifugal sedimentation method was 40 nm. In the centrifugal sedimentation method, isobutanol is used as a dispersion medium, and after stirring with a propeller stirrer, the particle size distribution is measured with a commercially available particle size distribution measuring device, and the 50% particle diameter (median diameter) based on the particle volume is defined as the average particle diameter. . The average secondary particle size of expanded graphite was measured in the same manner. When the specific surface area of carbon black is 30 m ² / g or more and 1000 m ² / g or less and the average particle diameter is 10 nm or more and 100 nm or less, the effect is not changed. Also, in place of acetylene black, furnace black, channel black, etc. having the same specific surface area and the same average particle diameter may be used, and the significance of carbon black is that it is a highly conductive fine and chemically stable powder. . Because graphite is in contact with dilute sulfuric acid electrolyte, expanded graphite obtained by treating graphite with sulfuric acid in advance was used. However, not only expanded graphite but also natural graphite or artificial graphite may be used. , Scales, etc. are optional. The expanded graphite used has a specific surface area of 20 m ² / g when nitrogen gas is adsorbed by the BET method and an average secondary particle diameter measured by the centrifugal sedimentation method of 45 μm. Not only expanded graphite, but graphite such as natural graphite and artificial graphite has the same effect as long as the specific surface area is 0.5 m ² / g or more and 50 m ² / g or less and the average secondary particle diameter is 10 μm or more and 500 μm or less. .

  Fibrous carbon having an average fiber length of 15 μm and an average fiber diameter of 150 nm when observed with an electron microscope was used. The effect of the fibrous carbon is not changed if the average length of the fibers is 2 μm or more and 50 μm or less, and the average diameter of the fibers is 50 nm or more and 300 nm or less. The fibrous carbon is a conductive fiber having a graphite structure. Fibrous carbon is sometimes referred to as carbon nanofiber because it has an average diameter on the order of submicrons, and is smaller in both diameter and fiber length than carbon fiber, and larger in both diameter and length than carbon nanotube. Fibrous carbon is an intermediate size between graphite and carbon black and has a high affinity with carbon black, so that it becomes a carrier and prevents the carbon black from flowing into the electrolyte. Carbon black, fibrous carbon, and graphite constitute a conductive network in the negative electrode active material, facilitating reduction of lead sulfate during charging.

  55g of positive electrode active material paste per positive electrode grid, 52g of negative electrode active material paste per negative electrode grid, each aged for 48 hours at 50 ° C and 50% relative humidity, then 24 hours in a dry atmosphere at 50 ° C It was made to dry and the unformed positive electrode plate and the negative electrode plate were obtained. A non-formed negative electrode plate is stored in a bag-shaped polyethylene separator, and eight unformed negative electrode plates and seven unformed positive electrode plates stored in the separator are alternately laminated, and the ears of the same polarity electrode plates are welded together. The electrode plate group was used. Six obtained electrode plate groups were accommodated in a polypropylene battery case and welded so that they were connected in series. At 20 ° C., the amounts of aluminum sulfate and lithium sulfate described in Table 1 were added to dilute sulfuric acid having a specific gravity of 1.230. The added electrolyte was poured, and a battery case was formed in a water bath at 25 ° C. to obtain a 55B24 type lead acid battery. An aluminum ion source and a lithium ion source are optional, and for example, in addition to aluminum sulfate and lithium sulfate, lithium carbonate, lithium aluminate, aluminum hydroxide and lithium hydroxide may be added.

Test method 5 hour rate capacity test (JIS D 5301: 2006 9.5.2b)) was conducted for lead storage batteries of each composition, and initial discharge capacity was obtained. Idling stop life test for lead storage batteries of each composition (Battery Manufacturers Association Standard SBA S 0101: 2006 9.4.5) to obtain idling stop life performance (SBA-IS life performance) and low temperature high-rate discharge test (JIS D 5301: 2006 9.5.3b)) The high rate discharge performance was determined. The results are shown in Table 1, the results when the carbon black content is changed are shown in FIG. 1, the results when the graphite content is changed are shown in FIG. 2, and the results when the fibrous carbon content is changed. Is shown in FIG. FIG. 4 shows the influence of the aluminum ion concentration in the electrolytic solution, and FIG. 5 shows the influence of the lithium ion concentration. The data in FIGS. 1 to 5 is a reprint of the data in Table 1. The result shows an average of three storage batteries, and contains 0.5 parts by mass of carbon black and 100 parts by mass of the negative electrode pre-formed active material, and does not contain graphite, fibrous carbon, aluminum ions, or lithium ions. The result of 1 is shown as a relative value with 100 as the value. In the following, when the content of carbon black or the like is shown, the value based on 100 parts by mass of the negative electrode already formed active material is omitted.

Results Regarding the initial discharge capacity, the practical tolerance is 95 or more, the idling stop life performance (SBA-IS life performance) is 120 or more, and the practical tolerance of high rate discharge performance is 95 or more. In the sample containing neither aluminum ion nor lithium ion, the SBA-IS life performance could be improved to near the target value by including carbon black, graphite, and fibrous carbon together. By including, for example, 0.1 mol / L of aluminum ions in the electrolyte solution in this system, the SBA-IS life performance reached the target value, but the high rate discharge performance decreased. In contrast, when carbon black, graphite, and fibrous carbon are included in the negative electrode active material, and aluminum ions and lithium ions are included in the electrolyte, initial discharge capacity, SBA-IS life performance, and high rate discharge performance. A lead storage battery satisfying the above was obtained (Sample 8). When fibrous carbon was not included, carbon black flowed out into the electrolyte after the SBA-IS test.

Fig. 1 shows the effect of carbon black content, Fig. 2 shows the effect of graphite content, and Fig. 3 shows the effect of fibrous carbon content. In these figures, the content of other additives is near the optimum amount. It is fixed to. The following is clear from FIGS.
・ SBA-IS life performance does not reach the target value even if carbon black, graphite, or fibrous carbon is missing.
-Carbon black and graphite have significantly different SBA-IS life performance at 0 and 0.1 parts by mass.
-In the case of fibrous carbon, the SBA-IS life performance is remarkably different between 0 and 0.05 parts by mass.
-In any case of carbon black, graphite, and fibrous carbon, if the content is increased unnecessarily, the initial discharge capacity decreases.
-Carbon black and graphite have a small effect on high rate discharge performance, but if high amounts of fibrous carbon are contained, especially more than 1 part by mass, the high rate discharge performance is significantly reduced.

FIG. 4 shows the effect of the aluminum ion concentration in the electrolytic solution, and FIG. 5 shows the effect of the lithium ion concentration in the electrolytic solution. The contents of carbon black, graphite and fibrous carbon in the negative electrode active material are optimum. It is fixed near the value. The following is clear from FIGS.
・ Aluminum ions are indispensable for achieving the target SBA-IS life.・ Aluminum ions have an adverse effect on high rate discharge performance, especially at over 0.2 mol / L. Up to 0.2 mol / L, the influence of aluminum ions on the high rate discharge performance is small.
-Lithium ions improve high rate discharge performance, and the additive that improves high rate discharge performance is only lithium ions within the experimental range. However, when lithium ions exceeding 0.2 mol / L are contained, the SBA-IS life performance decreases.

  1 to 5, the optimum content is 0.5 to 1.5 parts by mass for carbon black, 0.5 to 1.5 parts by mass for graphite, and 0.2 to 0.75 parts by mass for fibrous carbon. It can be seen that aluminum ions and lithium ions are 0.05 mol / L or more and 0.2 mol / L or less, respectively. However, if high-rate discharge performance is not important, it is not necessary to contain lithium ions.

Claims (2)

In a lead storage battery comprising a positive electrode plate made of a positive electrode lattice and a positive electrode material, a negative electrode plate made of a negative electrode lattice and a negative electrode material, and a dilute sulfuric acid electrolyte in which the positive electrode plate and the negative electrode plate are immersed,
The electrolyte contains 0.02 mol / L or more and 0.2 mol / L or less of aluminum ions,
The negative electrode material is 0.1 part by mass or more and 2 parts by mass or less of carbon black, 0.1 part by mass or more and 2 parts by mass or less of graphite, and 0.05 part by mass or more of fibrous carbon with respect to 100 parts by mass of the negative electrode active material. Lead acid battery, characterized by containing 1 part by mass or less.   The lead acid battery according to claim 1, wherein a lithium ion concentration of the electrolytic solution is less than 0.02 mol / L.

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