JP6015427B2 - Negative electrode plate for lead acid battery and method for producing the same - Google Patents

Description

  The present invention relates to a negative electrode plate for a lead storage battery and a manufacturing method thereof, and more particularly to a negative electrode plate containing a large amount of carbon black in a negative electrode active material and a manufacturing method thereof.

  One of the life factors of lead-acid batteries is sulfation, which is a phenomenon in which lead sulfate crystals that are difficult to reduce to spongy lead by charging grow in the negative electrode active material. Sulfation is one of the main life factors when a lead-acid battery is used under insufficient charging conditions, such as an idling stop vehicle. In order to suppress sulfation, it is known to increase the carbon black content in the negative electrode active material and to provide an electronically conductive network made of carbon black in the negative electrode active material. However, when carbon black is contained in a large amount, the negative electrode active material paste becomes hard and it becomes difficult to fill the lattice. Therefore, when the amount of water in the negative electrode active material paste was increased to facilitate filling of the lattice, the high rate discharge performance decreased with a decrease in the amount of lead in the negative electrode active material. Moreover, the durability to sulfation was insufficient.

Simply increasing the amount of carbon black does not solve the problem of sulfation. The challenges are:-Easy filling of the anode active material paste into the grid,
・ Keeping the high rate discharge performance higher than the current level,
・ And to improve the durability to sulfation. The inventor examined the achievement of these problems by paying attention to the density of the negative electrode active material paste, the dispersibility of carbon black in the negative electrode active material, and the pore size distribution in the negative electrode active material. It came to.

  Here is related prior art. Patent Document 1 (Japanese Patent Laid-Open No. 2006-196191) states that 0.22 to 1.28 mass% carbon black and 0.2 to 0.6 mass% bisphenolsulfonic acid polymer condensate are contained in the negative electrode active material of a liquid lead-acid battery. is suggesting. Patent Document 1 states that this composition improves charge acceptance and is optimal for an idling stop vehicle. Patent Document 1 does not mention the density of the negative electrode active material or the pore size distribution.

JP 2006-196191

  An object of the present invention is to provide a negative electrode plate for a lead-acid battery, which can be easily filled with a negative electrode active material paste, has a higher rate discharge performance than the current state, and is excellent in durability to sulfation, and a method for producing the same. .

The negative electrode plate for a lead storage battery of the present invention comprises a negative electrode active material mainly composed of spongy lead and a current collector such as a lead grid,
In the stage where the negative electrode active material is already formed,
Per 100 mass% of the spongy lead, containing 1.0 mass% to 2.5 mass% of carbon black and 0.1 mass% to 0.9 mass% of bisphenol condensate,
For pores with a median pore size on a volume basis (50 vol% pore size in the pore size cumulative distribution) of 0.5 μm or less and porosity (pore size of 300 μm or less), the pore volume was integrated. Is 0.22 mL / g or more and 0.4 mL / g or less.

The negative electrode active material of this invention is
・ Porosity is as high as 0.22mL / g or more and 0.4mL / g or less,
・ The median pore diameter is as small as 0.5μm or less,
・ Contains carbon black in the range of 1.0 mass% to 2.5 mass%,
-Containing 0.1 mass% or more and 0.9 mass% or less of bisphenol condensate.

  When a large amount of carbon black is contained in the negative electrode active material, the hardness of the negative electrode active material paste increases and it becomes unsuitable for filling. However, in the present invention, the hardness of the paste can be kept in a range suitable for filling by reducing the density of the negative electrode active material paste and including the bisphenol condensate. When carbon black is contained in a large amount and a bisphenol condensate is contained, the median pore diameter (pore diameter at 50 vol% in the integrated pore diameter distribution) is 0.5 μm or less, and the small diameter is small. The number of holes increases and charging / discharging inside the negative electrode active material becomes easy. Further, the bisphenol condensate uniformly disperses carbon black in the negative electrode active material and improves cycle life performance. It can be presumed that the uniform dispersion of carbon black contributes to eliminating the large pores due to the aggregation of carbon black and reducing the median pore diameter. For these reasons, since the porosity is high, even if the amount of lead is small, the high-rate discharge performance can be kept higher than the current level, and the cycle life performance can be improved. When lignin is included in the negative electrode active material, it can be estimated that the bisphenol condensate contributes to the suppression of carbon black adsorption by lignin, maintaining the shrinkage performance of lignin, and maintaining high rate discharge performance. .

  In this specification, the content of the carbon black and bisphenol condensate in the negative electrode active material indicates the amount of spongy lead in the negative electrode active material as 100 mass%. When the negative electrode active material contains lead sulfate or the like, the amount of spongy lead is determined by converting lead sulfate into spongy lead.

The bisphenol condensate is a water-soluble polymer composed of a bisphenol condensate having a sulfonic acid group as a substituent. Bisphenol condensates are for example
(-(OH) (RSO ₃ H) Ph-X-Ph (OH) (R'SO ₃ H) CH _2- ) _n
Wherein R and R ′ are appropriate alkyl groups such as a methylene group, X is a SO ₂ group, an alkyl group, etc., and two phenyl groups Ph may be directly bonded without containing X. . Further, the SO ₃ H group hydrogen may be substituted in the negative electrode active material by an appropriate cation, particularly an alkali metal ion such as Na + ion. Further, the RSO ₃ H group, the R′SO ₃ H group, and the CH ₂ group are located, for example, in an ortho position with respect to the OH group of the phenyl group Ph, and the monomers of the condensate are connected to each other via the CH ₂ group. Although many commercially available bisphenol condensates have two sulfonic acid groups per monomer, the number of sulfonic acid groups per monomer is arbitrary, such as 1 to 4. When X is SO ₂ group, bisphenol S, when X is —C (CH ₃ ) ₂ —, bisphenol A, when X is CH ₂ group are bisphenol F, and in the examples, bisphenol S is used. Bisphenol A, bisphenol F, etc. may be used. The molecular weight of the bisphenol condensate is arbitrary, for example, about 4000 to 250,000, and the influence of the molecular weight is small. A bisphenol condensate is similar to lignin sulfonic acid in that it is a water-soluble polymer containing an aromatic ring and a sulfonic acid group, but has no carboxy group, ether group, and alcoholic hydroxyl group, Instead, it is a linear polymer.

Preferably, the negative electrode active material has a median pore diameter of 0.25 μm or more and 0.5 μm or less. When the median pore diameter is less than 0.25 μm, the paste becomes hard and unsuitable for filling, and the high-rate discharge performance and cycle life performance deteriorate (12 and 13 in Table 1). When carbon black is contained in an amount of 1.0 mass% or more, if the density of the negative electrode active material exceeds 3.2 g / cm ³ , the paste becomes hard and is not suitable for filling (samples 3 and 7 in Table 1).

  Preferably, the negative electrode active material has a porosity of 0.22 mL / g or more and 0.3 mL / g or less. When the porosity exceeds 0.3 mL / g, both the high rate discharge performance and the cycle life performance deteriorate (samples 6 and 8 in Table 1). If the porosity is less than 0.22 mL / g, the paste is hard and unsuitable for filling, and the high rate discharge performance and cycle life performance are reduced (3 and 7 in Table 1).

  More preferably, the negative electrode active material contains 0.3 mass% to 0.7 mass% of bisphenol condensate per 100 mass% of spongy lead. Outside this range, cycle life performance begins to decline (Samples 15 and 16 in Table 1).

  The negative electrode plate for a lead storage battery of the present invention may be used for a liquid type, but is preferably used for a control valve type lead storage battery in which the negative electrode active material is less likely to fall off because pressure is applied by a separator.

Further, the present invention is a method for producing a negative electrode plate for a lead storage battery, comprising a negative electrode active material mainly composed of spongy lead and a current collector such as a lead grid.
Producing a carbon paste containing carbon black, a bisphenol condensate and water by kneading;
A step of kneading carbon paste, lead powder, sulfuric acid and water into a negative electrode active material paste having a density of 4.1 g / cm ³ or less and 3.0 g / cm ³ or more;
By filling the negative electrode active material paste into the lead lattice, aging, drying, and forming,
Per 100 mass% of spongy lead, carbon black is contained in an amount of 1.0 mass% to 2.5 mass% and a bisphenol condensate is contained in an amount of 0.1 mass% to 0.9 mass%, and the median pore diameter on a volume basis is 0.5 μm or less. And a formed negative electrode plate having a porosity (integrated pore volume for pores having a pore diameter of 300 μm or less) of 0.22 mL / g or more and 0.4 mL / g or less.

Note that the carbon paste may be kneaded again by adding the bisphenol condensate to the paste obtained by kneading the carbon black and water, even if the carbon black, the bisphenol condensate and water are kneaded in one step. Alternatively, kneading may be performed in two steps. The carbon paste may be added with a known third component such as Ba sulfate or synthetic resin fiber, or may be added with a known third component such as lignin in addition to lead powder, water and sulfuric acid. Chemical conversion may be either battery case conversion or tank formation. The conversion of the density of the negative electrode active material paste and the porosity of the formed negative electrode active material in this invention is shown. The density of the negative electrode active material paste is 4.1 g / cm ³ or less and 3.0 g / cm ³ or more, and the porosity is 0.22 mL / g or more and 0.4 mL / g or less, and 4.1 g / cm ³ or less and 3.6 g / cm ³ or more. However, the porosity corresponds to 0.22 mL / g or more and 0.3 mL / g or less. Further, the density of the negative electrode active material paste is 3.0 g / cm ³ or more and 4.1 g / cm ³ or less, and the density of the formed negative electrode active material is 2.0 g / cm ³ or more and 3.2 g / cm ³ or less. In this specification, the description regarding a negative electrode plate is applicable also to the manufacturing method of a negative electrode plate.

In the method for producing a negative electrode plate for a lead storage battery of the present invention,
Reducing the density of the negative electrode active material paste to 4.1 g / cm ³ or less to 3.0 g / cm ³ or more;
・ By including 0.1 mass% or more and 0.9 mass% or less of bisphenol condensate,
Even if carbon black is contained in an amount of 1.0 mass% to 2.5 mass%, the hardness of the negative electrode active material paste can be maintained in a range suitable for filling the lattice. In this specification, the contents of bisphenol condensate and carbon black are shown per 100 mass% of spongy lead. In addition, carbon black is contained in an amount of 1.0 mass% to 2.5 mass% and a bisphenol condensate is contained in an amount of 0.1 mass% to 0.9 mass%, thereby providing a large number of small-diameter pores and charging / discharging inside the negative electrode active material. To make it easier. Also, the carbon black is uniformly dispersed in the negative electrode active material by the bisphenol condensate to improve the cycle life performance. In this way, while reducing the amount of lead to improve the fillability, the high rate discharge performance is kept higher than the current level, and the cycle life performance is improved from the current level.

Manufacturing process diagram of negative electrode plate in Example Characteristic chart showing pore diameter distribution in negative electrode active material in Examples and Conventional Examples: The vertical axis represents differential pore volume dV / dLogD, and the horizontal axis represents pore diameter D in LogD units. Here, V is the amount of pores accumulated from D = 0, the unit is an arbitrary unit, and the number on the horizontal axis is the pore diameter D in μm units.

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

  Kneading water and carbon black, then condensate of bisphenol S as a dispersant (molecular weight about 100,000), 0.6 mass% Ba sulfate with 100 mass% spongy lead, and 100 mass% spongy lead 0.1 mass% synthetic resin fiber was added and kneaded. As carbon black, ketjen black or acetylene black gives almost the same result, and other carbon black such as oil furnace black may be used. Even when the bisphenol A condensate was used instead of the bisphenol S condensate, almost the same results were obtained, and even when the molecular weight of the bisphenol S condensate was changed to 10,000, the results were the same. Further, other bisphenol condensates such as bisphenol F condensate may be used, and Ba sulfate and synthetic resin fibers may not be added. The paste obtained as described above is called a carbon paste.

  Lead powder produced by the ball mill method, lignin sulfonic acid as a non-shrinking agent (0.2 mass% for 100 mass% spongy lead, hereinafter simply referred to as “lignin”), water, and sulfuric acid are added to the carbon paste and kneaded. To obtain a negative electrode active material paste. In addition, the kind and manufacturing method of lead powder are arbitrary. In the examples, a carbon paste in which carbon black and a bisphenol condensate are previously kneaded is mixed with lead powder. However, these may be separately added to the lead powder and kneaded.

  The negative electrode active material paste was filled in an expanded lattice made of a Pb—Ca—Sn alloy, and aged and dried according to a conventional method to obtain an unformed negative electrode plate. A positive electrode active material paste consisting of 0.1 mass% synthetic resin fiber, water and sulfuric acid is filled into 100 mass% lead powder in an expanded lattice made of a Pb-Ca-Sn alloy, and is subjected to aging and drying according to a conventional method. An unchemically formed positive electrode plate was obtained. A glass mat retainer is sandwiched between the negative electrode plate and the positive electrode plate, set in a battery case with pressure applied, and sulfuric acid (specific gravity after chemical conversion is 1.30) is held by a separator such as a glass mat retainer. The battery was formed in accordance with the control valve type lead-acid battery. The type of the separator is arbitrary and may be a liquid lead-acid battery, and the chemical conversion may be a tank chemical. The electrode configuration consists of 2 positive plates and 1 negative plate for measuring initial performance (low temperature high rate discharge performance), 5 hR capacity of 8 Ah, 7 positive plates and 8 negative plates for durability performance evaluation, The 5hR capacity was 48Ah. The production method up to the unformed negative electrode plate is shown in FIG.

During the preparation of the negative electrode active material pastes were varying amounts of water the density of the paste was varied in the range of 2.8 g / cm ³ of 4.4 g / cm ^3. This is the range of the active material density of the already Kasei equivalent from 1.8 g / cm ³ to 3.5 g / cm ^3, as the range of the porosity of the anode active material was equivalent from 0.46 mL / g to 0.19 mL / g. The carbon black content was changed in the range of 0.3 mass% to 3 mass% with respect to 100 mass% of the lead powder, and the amount of the bisphenol condensate was changed in the range of 0 to 1.0 mass% with respect to 100 mass% of the lead powder.

  The density, porosity, and pore size distribution of the negative electrode active material were measured for the formed negative electrode plate, and the pore size (center pore size) at a pore volume of 50 vol% was measured. In this specification, the amount of inclusion is indicated by the content with respect to 100 mass% of spongy lead, and the composition of the negative electrode active material reduces lead sulfate to spongy by charging the negative electrode plate as necessary. The negative electrode active material is separated from the negative electrode plate, measured after washing with water and drying. The density of the formed negative electrode active material was determined by the following procedure. The total density was determined by adding the true density of each composition material as d, the content per 1 g of the negative electrode active material as m, the volume as m / d, and adding m / d for each composition material. Porosity was added to this sum to obtain a volume per 1 g of the negative electrode active material, and the reciprocal thereof was taken as the density of the preformed negative electrode active material. The distribution of porosity and pore diameter is measured by mercury porosimetry, and the porosity is the pore volume per gram of the negative electrode active material, not the pore volume per gram of spongy lead. The pores were measured with an upper limit of 300 μm. Further, the penetration was measured according to JIS K2207 as an index showing the filling property of the negative electrode active material paste into the lattice.

  As the initial performance, high-rate discharge performance at low temperature was evaluated, and the discharge time until the terminal voltage decreased to 1.0 V at a discharge current of 37.5 A at an ambient temperature of −15 ° C. was measured. Evaluate cycle performance under insufficient charging conditions as durability performance, discharge at 60 ° C with discharge current 50A for 60 seconds at ambient temperature 25 ° C, repeat constant voltage charge cycle at 2.33V for 60 seconds with maximum current 50A, The number of cycles until the terminal voltage during discharge fell below 1.0 V was measured. The value is shown by the result of one battery each. Table 1 shows the configuration and evaluation results of the control valve type lead-acid battery. In Table 1, the penetration is 50 to 100 or less (70 in the conventional example, can be filled in the same way as the conventional example), and over 130 is less than 130 (filling is difficult because the paste is soft), less than 50 ( The paste was too hard and filling was extremely difficult) and over 130 (the paste was too soft and the possibility of the negative electrode active material falling off) was rated as x. The low-temperature, high-rate discharge performance requires 150 seconds or more as in the conventional example, and the cycle life performance requires 20,000 cycles or more for use in an idling stop vehicle or the like.

When the density of the pre-formed negative electrode active material is fixed at 3.5 g / cm ³ and the carbon black content is increased (Samples 1 and 2), the paste is cured and the filling property is lowered, and the low-temperature high-rate discharge performance is lowered. The cycle life performance is not improved. The decrease in the low-temperature and high-rate discharge performance can be presumed to be due to the fact that the lignin adsorbs carbon black, thereby reducing the function as an anti-shrink agent. Increasing the carbon black content and containing the bisphenol condensate (Sample 3) improves the penetration but is still in an impractical range, improves the low-temperature high-rate discharge performance over the conventional example, and improves the cycle. The service life has reached a practical range.

If the carbon black content is 0.3 mass% and the density of the negative electrode active material is reduced from 3.5 g / cm ³ to 2.7 g / cm ³ (sample 4), the penetration will reach 200 and the performance cannot be evaluated. It was. Here, when the carbon black content is 1.5 mass% (Sample 5), even if the density of the negative electrode active material is 2.7 g / cm ³ , the penetration is 60 and practical, but the low-temperature high-rate discharge performance is The cycle life was significantly reduced and the cycle life was also lower than that of the conventional example. This is due to the decrease in lead content and lignin adsorbing carbon black, resulting in reduced shrinkage performance, resulting in lower low-temperature, high-rate discharge performance, and lower cycle life due to reduced lead content and high-rate discharge performance. Can be estimated. On the other hand, when the density of the already formed active material is reduced to 2.7 g / cm ³ to increase the carbon black content and the bisphenol condensate is contained as in the example of Sample 6, the penetration is practical. Thus, the low-temperature high-rate discharge performance is improved and the cycle life is also improved. The sample 6 has a longer cycle life than the sample 3 although the amount of lead is smaller.

When the density of the pre-formed negative electrode active material is 2.0 to 3.2 g / cm ³ , excellent performance is obtained (samples 6 to 8), and when it is 1.8 g / cm ³ , both penetration, low temperature and high rate discharge performance, and cycle life are obtained. When the amount was 3.5 g / cm ³ as described above, the penetration was impractical (Sample 3). By fixing the density of the pre-formed negative electrode active material and the amount of bisphenol condensate and changing the carbon black content, the low-temperature high-rate discharge performance can be significantly improved by increasing from 0.9 mass% to 1.0 mass%, from 2.5 mass% When it increased to 3.0 mass%, performance fell in all the items (samples 10-13). By fixing the density and carbon black content of the preformed negative electrode active material and changing the amount of bisphenol condensate, the performance improves in all items by increasing from 0.05 mass% to 0.1 mass%, from 0.9 mass% When it increased to 1.0 mass%, the performance fell in all items (samples 14 to 17).

  The median pore size decreased with increasing carbon black content or increasing bisphenol condensate content. Good results are obtained when the median pore diameter is 0.5 μm or less, particularly 0.25 μm or more and 0.5 μm or less. FIG. 2 shows the pore size distribution of the formed negative electrode active material in Sample 1 (conventional example) and Sample 6 (Example). Sample 1 (conventional example) has two peaks with a pore diameter of more than 1 μm and less than 1 μm, and sample 6 (Example) has a peak with a pore diameter of more than 1 μm disappeared. The large number of pores having a diameter of 0.5 μm or less means that charging and discharging can be performed efficiently, which compensates for the shortage of lead amount, and maintains low temperature and high rate discharge performance more than the conventional example. Can be estimated. The bisphenol condensate can be presumed to have improved penetration and improved cycle life by uniformly dispersing carbon black in the negative electrode active material. Furthermore, it can be estimated that the bisphenol condensate has improved low-temperature high-rate discharge performance by suppressing the adsorption of carbon black by lignin.

From the above, the configuration of the negative electrode plate is preferably as follows.
The density of the pre-formed negative electrode active material is 2.0 g / cm ³ or more and 3.2 g / cm ³ or less, particularly 2.5 g / cm ³ or more and 3.2 g / cm ³ or less;
-The porosity of the preformed negative electrode active material is 0.22 mL / g or more and 0.4 mL / g or less, particularly 0.22 mL / g or more and 0.3 mL / g or less;
-The median pore diameter on a volume basis is 0.5 μm or less, especially 0.25 μm or more and 0.5 μm or less;
-Carbon black content is 1.0mass% or more and 2.5mass% or less;
-The bisphenol condensate content is 0.1 mass% or more and 0.9 mass% or less, particularly 0.3 mass% or more and 0.7 mass% or less.

  Although the control valve type lead storage battery is shown in the embodiment, a liquid type may be used. Table 2 shows the performance when using the same negative electrode plate as in Table 1 and changing to the liquid type. The low-temperature, high-rate discharge performance is improved in the same manner in both the control valve type and the liquid type, but the cycle life performance is less improved in the liquid type. It can be estimated that this is because the liquid-type lead-acid battery does not apply pressure to the negative electrode plate, so that the low-density negative electrode active material is easily dropped.

  The negative electrode plate may contain substances other than those described above. For example, water-soluble polymers such as carboxymethyl cellulose, polyacrylic acid, alginic acid, and alkali metal salts thereof may be contained in the negative electrode active material.

Claims (3)

In the negative electrode plate for a lead storage battery, comprising a negative electrode active material mainly composed of spongy lead and a current collector,
In the stage where the negative electrode active material is already formed,
Per 100 mass% of the spongy lead, containing 1.0 mass% to 2.5 mass% of carbon black and 0.1 mass% to 0.9 mass% of bisphenol condensate,
A negative electrode plate for a lead storage battery, wherein the median pore diameter on a volume basis is 0.5 µm or less and the porosity is 0.22 mL / g or more and 0.4 mL / g or less. 2. The negative electrode for a lead storage battery according to claim 1, wherein the negative electrode active material has a median pore diameter of 0.25 μm to 0.5 μm and a density of 2.0 g / cm ^{3 to} 3.2 g / cm ^3. Board. In the method for producing a negative electrode plate for a lead storage battery, comprising a negative electrode active material mainly composed of spongy lead and a current collector,
Producing a carbon paste containing carbon black, a bisphenol condensate and water by kneading;
A step of kneading carbon paste, lead powder, sulfuric acid and water into a negative electrode active material paste having a density of 4.1 g / cm ³ or less and 3.0 g / cm ³ or more;
By filling the negative electrode active material paste into the lead lattice, aging, drying, and forming,
Per 100 mass% of spongy lead, carbon black is contained in an amount of 1.0 mass% to 2.5 mass% and a bisphenol condensate is contained in an amount of 0.1 mass% to 0.9 mass%, and the median pore diameter on a volume basis is 0.5 μm or less. A method for producing a negative electrode plate for a lead storage battery, wherein the negative electrode plate is formed with a porosity of 0.22 mL / g or more and 0.4 mL / g or less.