JP4970348B2 - Negative electrode active material mixture for lead-acid batteries - Google Patents

Description

The present invention relates to a negative electrode active material mixture for a lead storage battery and a negative electrode plate for a lead storage battery including the same.

In recent years, against the background of increasing awareness of global environmental problems, there is an increasing interest in power generation methods using wind power or sunlight as clean power generation methods that do not emit carbon dioxide, which is a cause of global warming. However, these power generation methods are easily affected by natural conditions and are used in various charging states (hereinafter referred to as PSOC) depending on the power generation state of wind power and solar power generation. May cause trouble.

In order to prevent the generation current from suddenly flowing into the system, a power storage facility for storing electric power may be provided alongside wind power and solar power generation. As the power storage equipment, lead storage batteries still dominate even today because of their high reliability due to their low cost and stable performance. However, when the lead storage battery is used for rapid charge / discharge and various PSOCs, the negative electrode of the lead storage battery has a smaller surface area than the positive electrode, so that the diffusion of the electrolyte is rate-determining and the polarization increases. Therefore, the conventional lead storage battery needs to be enlarged. In addition, when lead acid batteries are repeatedly charged and discharged with various PSOCs, lead sulfate as a discharge material is generated in the negative electrode by a dissolution and precipitation reaction, which leads to a decrease in conductivity and an increase in polarization. . In order to solve this problem, it has been proposed to add granular carbon powder as a conductive agent for a negative electrode plate for a lead storage battery, but this alone has not yielded a lead storage battery that exhibits excellent charge / discharge performance in PSOC. .

In order to solve such a problem, an attempt has been made to use an active material mixture paste obtained by adding a predetermined amount of conductive carbon and activated carbon to a negative electrode active material for a negative electrode for a lead storage battery (Patent Document 1). ). According to this attempt, the negative electrode polarization can be reduced and the battery voltage immediately after the start of discharge can be kept high.

However, in this trial, a lead-acid battery using a negative electrode active material in which the amount of conductive carbon and activated carbon added is 8 parts by mass or more in total with respect to 100 parts by mass of the negative electrode active material, and wind power or solar power generation are provided side by side. When used in various PSOCs, the growth of spongy lead on the negative electrode is inhibited, and the bond strength between the negative electrode active material particles is reduced. Therefore, there arises a problem that the high-rate discharge performance is lowered due to a decrease in conductivity, and the active material is dropped to shorten the battery life. Thus, there is a limit to the amount of conductive carbon and activated carbon that can be included in the negative electrode, and thus there is a limit to the increase in the electric double layer capacity of the negative electrode. In addition, the expansion and contraction of the negative electrode plate due to charge / discharge creates a passage for the electrolyte to pass through the active material, and conductive carbon and activated carbon in the active material, especially conductive carbon with a small particle diameter, leaks into the electrolyte. However, it may enter the separator and cause a short circuit.

On the other hand, there is a problem that the active material is dropped from the substrate constituting the electrode plate due to the charging / discharging of the battery as a cause of the battery performance deterioration. In order to solve this problem, there is an attempt to use a lattice body obtained by mechanically twisting and deforming a lattice body in which a gap to be filled with an active material is formed by punching as a substrate constituting an electrode plate (patent) Reference 2).

However, the strength of the lattice is reduced due to torsional deformation, and sometimes the lattice is damaged. Therefore, it is necessary to carefully perform torsional deformation, and much labor and time are required for manufacturing.

Japanese Patent Laid-Open No. 2003-51306 Japanese Utility Model Publication No. 40-13472

The present invention has remarkably high conductivity and therefore can not only increase the electric double layer capacity of the negative electrode, but also prevent short circuit due to leakage of carbon material, and therefore can provide significantly longer battery life. The present invention provides a negative electrode active material mixture for a lead storage battery, and a negative electrode plate for a lead storage battery comprising a substrate that can effectively prevent the negative electrode active material mixture from falling off and can be manufactured easily and inexpensively.

The present inventor has tried various studies to solve the above problems. As a result, they came up with adding conductive fibers to the negative electrode active material mixture described in Patent Document 3. When the conductive fiber is added, the fiber surface is ionized and bonded to activated carbon and carbon materials such as carbon black, graphite, and carbon fiber, and these are supported on the surface of the conductive fiber. Therefore, increasing the amount of activated carbon and the addition of these carbon materials not only inhibits the growth of spongy lead in the negative electrode, but can significantly increase the conductivity between the active materials, as well as the carbon materials that leak into the electrolyte. It has been found that the amount can be greatly reduced and short circuit can be prevented. In addition, since the conductivity between the active materials can be remarkably increased, when using activated carbon and a carbon material having a relatively high conductivity such as carbon black, graphite, carbon fiber, etc., these carbon materials having a high conductivity are used. It has been found that high conductivity can be maintained even when the amount is reduced, and accordingly, the amount of activated carbon can be increased correspondingly, and the electric double layer capacity of the negative electrode can be increased. In addition, since the conductive fibers form a fine matrix of a large number of conductive fibers in the negative electrode active material, the mechanical strength of the negative electrode active material is increased, and even if the amount of activated carbon is increased, the activated carbon moves and aggregates. Softening of the negative electrode active material mixture due to can be prevented, and the battery life can be extended.

Further, the present inventor can improve the entanglement between the conductive fibers and the substrate contained in the active material mixture, if a substrate having a predetermined structure is used as the substrate constituting the negative electrode plate, It has also been found that the adhesion between the negative electrode active material mixture and the substrate can be further improved to prevent the negative electrode active material mixture from falling off the substrate, thereby extending the battery life.

That is, the present invention
(1) (A) 100 parts by mass of negative electrode active material,
(B) sulfuric acid resistant conductive fiber (excluding components (C) and (D)) 1-2 parts by weight,
(C) 1-5 parts by mass of activated carbon, and
(D) 1 or more types of carbon materials (excluding component (C)) 1 to 5 parts by mass each
(Here, the total amount of component (C) and component (D) is 2 to 10 parts by mass)
Is a negative electrode active material mixture for lead storage batteries.

As a preferred embodiment,
(2) The negative electrode active material mixture for lead-acid batteries according to (1) above, wherein the total amount of component (C) and component (D) is 8 to 10 parts by mass,
(3) The total amount of component (C) and component (D) is more than 8 parts by weight and 10 parts by weight or less, the negative electrode active material mixture for lead-acid batteries according to (1) above,
(4) The negative electrode active material mixture for lead-acid batteries according to any one of (1) to (3) above, wherein component (B) is selected from the group consisting of metal fibers and fibers coated with metal ,
(5) The negative electrode active material mixture for lead-acid batteries according to (4) above, wherein the metal fibers are lead fibers and tin fibers,
(6) The negative electrode active material mixture for a lead storage battery according to (4) above, wherein the fiber coated with metal is a glass fiber coated with SnO ₂ ,
(7) The negative electrode active material mixture for a lead storage battery according to any one of (1) to (6) above, wherein the component (D) is selected from the group consisting of carbon black, graphite, and carbon fiber,
(8) The negative electrode active material mixture for a lead storage battery according to any one of (1) to (6) above, wherein the component (D) is carbon black,
(9) A negative electrode plate for a lead storage battery comprising the negative electrode active material mixture for a lead storage battery according to any one of (1) to (8) above,
(10) The substrate constituting the lead-acid battery negative electrode plate has a plurality of polygonal active material mixture filling spaces, and has protrusions on all or part of the polygonal sides forming the spaces. The negative electrode plate for a lead storage battery according to (9) above,
(11) The negative electrode plate for a lead storage battery according to the above (10), wherein the polygonal active material mixture filling space is a triangle, rectangle, square, pentagon or hexagon,
(12) The negative electrode plate for a lead storage battery according to the above (10), wherein the polygonal active material mixture filling space is substantially a regular hexagon.
(13) The negative electrode plate for a lead storage battery according to any one of the above (9) to (12), wherein the protrusions are provided on all of the sides of the polygon forming the space for filling the active material mixture. Can be mentioned.

The negative electrode active material mixture for a lead storage battery of the present invention has remarkably high conductivity, and therefore can not only increase the electric double layer capacity of the negative electrode, but also prevent a short circuit due to leakage of the carbon material. , Can provide a significantly longer battery life. Moreover, the negative electrode plate of the present invention provided with the negative electrode active material mixture can not only effectively prevent the negative electrode active material mixture from falling off, but also can be produced simply and inexpensively.

The conductive fiber having component (B) sulfuric acid resistance of the present invention increases the conductivity of the active material mixture and is used as a support for supporting the active material. The upper limit of the diameter of the conductive fiber is preferably 100 μm, more preferably 60 μm, and the lower limit is preferably 10 μm, more preferably 20 μm. If the above upper limit is exceeded, no significant increase in the effect is observed, and if it is less than the above lower limit, the conductivity cannot be sufficiently increased, and it does not sufficiently act as a support for the active material. Further, the upper limit of the length of the conductive fibers is preferably 10 mm, more preferably 5 mm, and the lower limit is preferably 1 mm, more preferably 3 mm. When the above upper limit is exceeded, the conductive fiber is cut and shortened during the preparation of the active material mixture, and a sufficient effect corresponding to the fiber length cannot be obtained. If it is less than the said minimum, not only cannot it fully improve electroconductivity but it does not fully act as a support body of an active material. The diameter and length of the conductive fiber are preferably about 20 μm and 3 mm, for example. The conductive fiber having component (B) sulfuric acid resistance preferably includes metal fiber and metal-coated fiber. Examples of metal fibers include lead fibers and tin fibers. Examples of the fiber coated with metal include glass fiber coated with SnO ₂ .

The upper limit of the amount of the conductive fiber is 2 parts by mass with respect to 100 parts by mass of the component (A) negative electrode active material, and the lower limit is 1 part by mass. If the above upper limit is exceeded, no significant increase in the effect is recognized, and the proportion of the active material is reduced as a whole, and the battery life is reduced. On the other hand, if it is less than the said minimum, activated carbon and a carbon material cannot be carry | supported favorably and battery life cannot be improved.

Component (C) activated carbon is used to increase the electric double layer capacity of the negative electrode. As the activated carbon, one having a relatively large specific surface area is used. The upper limit of the specific surface area of the activated carbon used in the present invention is preferably 2500 m ² / g, more preferably 2400 m ² / g, and the lower limit is preferably 1000 m ² / g, more preferably 1600 m ² / g. . Beyond the above upper limit, the effect is saturated and the electric double layer capacity cannot be increased remarkably. On the other hand, below the lower limit, an increase in the electric double layer capacity of the negative electrode cannot be achieved. The upper limit of the particle diameter of the activated carbon is preferably 50 μm, more preferably 40 μm, and the lower limit is preferably 3 μm, more preferably 10 μm. Outside the above range, the electric double layer capacity of the negative electrode cannot be increased sufficiently. As this activated carbon, what was manufactured from coconut husk, petroleum pitch, petroleum coke, coal tar pitch, a phenol resin, etc. is used, for example, any of granular or fibrous form may be used.

The upper limit of the amount of the activated carbon is 5 parts by mass with respect to 100 parts by mass of the component (A) negative electrode active material, and the lower limit is 1 part by mass, preferably 3 parts by mass. If the above upper limit is exceeded, no significant increase in the effect is recognized, and the proportion of the active material is reduced as a whole, and the battery life is reduced. On the other hand, below the lower limit, the electric double layer capacity of the negative electrode cannot be increased, and the battery life cannot be increased.

Component (D) carbon material is used to increase the conductivity of the active material mixture. Therefore, carbon materials having relatively high conductivity, preferably carbon black such as acetylene black, furnace black, thermal black, channel black, ketjen black, powdery or fibrous graphite, and pitch-based or PAN-based carbon fiber, etc. Carbon fiber or the like is used. Among these, carbon black is particularly preferably used. These may be used alone or in combination of two or more.

The upper limit of the amount of the carbon material is 5 parts by mass with respect to 100 parts by mass of the component (A) negative electrode active material, and the lower limit is 1 part by mass, preferably 3 parts by mass. If the above upper limit is exceeded, no significant increase in the effect is recognized, and the proportion of the active material is reduced as a whole, and the battery life is reduced. On the other hand, if it is less than the said minimum, the electroconductivity of an active material mixture cannot be raised and a battery life cannot be raised.

The upper limit of the total amount of component (C) and component (D) is 10 parts by mass with respect to 100 parts by mass of component (A) negative electrode active material. The lower limit is 2 parts by mass, preferably 8 parts by mass, and more preferably more than 8 parts by mass with respect to 100 parts by mass of the component (A) negative electrode active material. If the above upper limit is exceeded, no significant increase in the effect is recognized, and the proportion of the active material is reduced as a whole, and the battery life is reduced. On the other hand, if it is less than the above lower limit, the battery life cannot be increased.

As the component (A) negative electrode active material, materials known as a negative electrode active material of a lead storage battery, that is, lead powder and lead oxide can be used. These may be used alone or in combination.

In addition to the above components, the negative electrode active material mixture for lead-acid batteries of the present invention can contain natural or synthetic lignin and barium sulfate as a shrinkage-preventing agent. Lignin can be included preferably in an amount of 0.1 to 0.5 parts by mass with respect to 100 parts by mass of the negative electrode active material. Moreover, barium sulfate can be preferably included in an amount of 0.5 to 3.0 parts by mass with respect to 100 parts by mass of the negative electrode active material. By including these, aggregation of a negative electrode active material can be suppressed and the performance fall by repetition of charging / discharging can be suppressed.

The negative electrode active material mixture for a lead storage battery of the present invention is usually applied or filled into a substrate constituting the negative electrode plate for a lead storage battery according to a known method. A well-known thing can be used as a board | substrate which comprises the negative electrode plate for lead acid batteries. Preferably, a substrate having a plurality of polygonal active material mixture filling spaces and having protrusions on all or part of the sides of the polygons forming the spaces is used. The protrusions are preferably provided on all of the polygonal sides forming the space for filling the active material mixture. The protrusion can effectively prevent the active material mixture from falling off the substrate by being entangled with the components contained in the active material mixture, in particular, the component (B) conductive fibers. The polygon forming the active material mixture filling space is not particularly limited, and may preferably be a triangle, a rectangle, a square, a pentagon or a hexagon. More preferably, a substantially regular hexagonal active material mixture filling space is provided. The polygonal space of the substrate can preferably be produced by stamping. When punching out so that Paris is intentionally formed at the time of punching, the projecting portion can be easily formed.

The negative electrode plate for a lead storage battery of the present invention thus obtained can be assembled into a lead storage battery according to a known method.

Substances and other battery materials used in Examples and Comparative Examples, and test methods are as follows.

material
<Ingredient (A)>
Lead powder: particle size 2-20μm, average particle size 7.5μm
<Ingredient (B)>
Lead fiber: Diameter 20-60μm, length 3-5mm
<Ingredient (C)>
Activated carbon: particle size 3-50μm, specific surface area 2400 m ² / g
<Ingredient (D)>
Carbon black: particle size 20-100μm
<Other ingredients>
Barium sulfate lignin: Nippon Paper Chemical Co., Ltd., Vanillex N (trademark)
Sulfuric acid electrolyte: manufactured by dissolving 20 grams of sodium sulfate in 1 liter of water. The specific gravity is 1.20.

Battery material
<Board>
As the negative substrate, the substrates (a) and (b) shown in FIGS. 1 and 2 were used. Each of the substrates has a substantially regular hexagonal active material mixture filling space (1). The substrate (b) has the protruding portions (2) shown in FIG. 2 on all of the hexagonal sides forming the space. The substrate (a) does not have the protrusion. As for the dimensions of the substrates (a) and (b), the electrode part is 40.0 × 75 mm, the ear part is 4 × 12.0 mm, and the electrode part and the ear part are both 2.0 mm in thickness. The thickness of the substrate (b) including the protruding portion is 3.0 mm. The regular hexagonal hole has a diameter of 6 to 12 mm.
The dimensions of the positive electrode plate are 40.0 × 73.0 mm for the electrode portion, 4 × 12.0 mm for the ear portion, 4.0 mm for the electrode portion, and 3.8 mm for the ear portion.
The negative electrode substrate and the positive electrode substrate are both made of lead-calcium alloy.
<Retainer mat separator>
Made by Nippon Sheet Glass Co., Ltd., FM920N (trademark), 10 parts by mass of silica fine powder is added to 100 parts by mass of fine glass short fibers having an average diameter of 1 μm or less, and paper is made into a mat shape. The retainer mat separator has a thickness of 0.8 mm when pressurized to 20 kPa.
<Battery>
Made of ABS resin, the dimensions are 65.0mm x 150mm x 85.0mm.

Test method
<Charge / discharge cycle life test>
The discharge current was 0.13 CA and the charge current was 0.14 CA so that the charge amount / discharge amount was 104%. The test was conducted at an ambient temperature of 25 ° C. The battery life was defined as the number of cycles when the discharge voltage reached 0 V in the test.

(Examples 1 to 9)
Each component was mixed in the blending amount (parts by mass) shown in Table 1. Next, 15 parts by mass and 6 parts by mass of ion-exchanged water and dilute sulfuric acid (specific gravity: 1.4) were added and mixed with 100 parts by mass of lead powder, respectively, to produce a negative electrode active material mixture paste. The paste was filled in each negative electrode substrate of the type shown in Table 1, and then aged for 24 hours at 40 ° C. and 95% humidity, and then dried to produce an unformed negative electrode plate.

On the other hand, with respect to 100 parts by mass of lead oxide as the positive electrode active material, 10 parts by mass and 10 parts by mass of ion-exchanged water and dilute sulfuric acid (specific gravity: 1.27) were added and mixed to produce a positive electrode active material paste. . The paste was filled in a positive electrode substrate, then aged at 40 ° C. and 95% humidity for 24 hours, and then dried to produce an unchemically formed positive electrode plate.

The four negative electrode plates and the three positive electrode plates thus manufactured were laminated via a retainer mat separator, and the same polarity ear rows were welded to assemble an electrode plate group for each example. Each electrode plate group was housed in an ABS resin battery case and sealed, and then 50.0 cc of sulfuric acid electrolyte (specific gravity: 1.20) was injected. This was overcharged at 40 ° C by 200% of its theoretical capacity to form a battery case, and a sealed lead-acid battery with a voltage of 2V was manufactured. The specific gravity of the electrolyte of each battery was 1.260. Further, in the capacity test of each battery conducted after the chemical conversion, the 5-hour rate capacity was 7 Ah.

(Comparative Examples 1 to 9)
The same procedure as in the above example was performed except that the blending amount (part by mass) and the type of the negative electrode plate shown in Table 2 were used.

A charge / discharge cycle life test was conducted using each of the sealed lead-acid batteries of Examples and Comparative Examples produced as described above. The results are shown in Tables 1 and 2. In Tables 1 and 2, the units of each component, barium sulfate and lignin are all parts by mass.

Example 1 uses a conventional substrate having no protrusion as a negative electrode substrate. Although the battery life was relatively short, the battery life was longer than that of Comparative Example 1 using a conventional active material mixture. In Example 2, a substrate provided with a protrusion as a negative electrode plate is used. Compared with Example 1, it was possible to reduce the amount of active material falling off, and the battery life was extremely good. In Example 3, the amount of the component (B) lead fiber is increased with respect to Example 2. In addition, battery life has increased. This is thought to be due to the fact that component (C) activated carbon and component (D) carbon black are more supported on lead fibers due to the increase in the amount of lead fibers. In Examples 4 and 5, the total amount of activated carbon and carbon black was made the same as in Example 3, and the blending amount of activated carbon and carbon black was maximized, respectively. From these examples, it was found that increasing the amount of activated carbon can further increase the battery life. In Example 6, the blending amount of lead fibers is the same as in Example 3, and the blending amount of activated carbon and carbon black is minimized. Although the battery life was reduced, it was sufficiently satisfactory as a lead-acid battery. In Example 7, the blending amount of lead fibers is the same as in Example 3, and the blending amount of activated carbon and carbon black is maximized. The battery life was sufficiently satisfactory as a lead-acid battery. Example 8 is obtained by increasing the amount of carbon black added to Example 3. Example 9 is obtained by increasing the blending amount of activated carbon with respect to Example 3. In all cases, the life increased by 15 to 20 cycles as compared with Example 3.

On the other hand, Comparative Examples 1 and 2 do not contain any component (b) lead fiber. Regardless of the type of the negative electrode substrate, the battery life was extremely bad. When these batteries were disassembled after the charge / discharge cycle life test, carbon black in the negative electrode plate flowed out and adhered to the separator. As described above, a large amount of carbon black was found to flow out without the lead fiber. In Comparative Example 3, no carbon black was added to Example 4. In Comparative Example 4, activated carbon was not added to Example 5. In any of the comparative examples, the battery life was extremely bad. In Comparative Example 5, the amounts of activated carbon and carbon black are increased beyond the scope of the present invention. The battery life was extremely bad. It is considered that this is because the effect is saturated and the desired effect cannot be obtained even if these components are increased more than necessary, and the amount of the active material is reduced as a whole. In Comparative Example 6, the amount of lead fibers added to Example 3 is increased beyond the scope of the present invention. The battery life was extremely bad. It is considered that this is because the effect is saturated and the desired effect cannot be obtained even if the lead fiber is increased more than necessary, and the amount of the active material is reduced as a whole. In Comparative Examples 7 and 8, the total amount of activated carbon and carbon black is within the scope of the present invention, but any component exceeds the scope of the present invention. In any case, the battery life was extremely bad. In Comparative Example 9, the total amount of activated carbon and carbon black is within the range of the present invention, but the amount of any component is less than the range of the present invention. The battery life was extremely bad.

The negative electrode active material mixture for a lead storage battery of the present invention can not only increase the electric double layer capacity of the negative electrode, but also can impart a remarkably long battery life to the lead storage battery. Therefore, the lead storage battery provided with the negative electrode active material mixture for the lead storage battery of the present invention can be effectively used for power storage facilities for wind power generation and solar power generation.

It is the top view and a-a 'sectional view of a negative electrode substrate (a). It is a top view and b-b 'sectional view of a negative electrode substrate (b).

Explanation of symbols

1 Active material mixture filling space 2 Projection

Claims (7)

(A) 100 parts by mass of the negative electrode active material,
(B) sulfuric acid resistant conductive fiber (excluding components (C) and (D)) 1-2 parts by weight,
(C) 1-5 parts by mass of activated carbon, and
(D) 1 or more types of carbon materials (excluding component (C)) 1 to 5 parts by mass each
(Here, the total amount of component (C) and component (D) is 2 to 10 parts by mass)
A negative electrode active material mixture for lead-acid batteries. 2. The negative electrode active material mixture for a lead storage battery according to claim 1, wherein the total amount of the component (C) and the component (D) is 8 to 10 parts by mass. 3. The negative electrode active material mixture for a lead storage battery according to claim 1 or 2, wherein the component (B) is selected from the group consisting of metal fibers and fibers coated with metal. The negative electrode active material mixture for a lead storage battery according to any one of claims 1 to 3, wherein the component (D) is selected from the group consisting of carbon black, graphite, and carbon fiber. The negative electrode active material mixture for a lead storage battery according to any one of claims 1 to 3, wherein the component (D) is carbon black. A negative electrode plate for a lead storage battery, comprising the negative electrode active material mixture for a lead storage battery according to any one of claims 1 to 5. The substrate constituting the negative electrode plate for a lead-acid battery has a plurality of polygonal active material mixture filling spaces, and has protrusions on all or part of the sides of the polygons forming the spaces. 6. The negative electrode plate for a lead storage battery according to 6.

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