lead-acid battery

Abstract

Lead-acid batteries have separators that store the electrolyte solution between the positive and negative electrode plates. And the electrical storage tank, the negative electrode material, a mixture of bisphenol condensate and volume ratio. The theoretical coefficient of difference between the negative and positive electrode materials is 0.85 or higher and does not exceed 1.2. In other words, it can increase the charging capacity while limiting the degradation of the charge. It can become liquid;

Description

This invention relates to a lead-acid battery in which the negative electrode active material contains a bisphenol condensate. In retainer-type lead-acid batteries, the electrolyte is held in a retainer such as a mat-shaped separator, and the oxygen and hydrogen generated during charging are converted back into water by a sealed reaction. Patent Document 1 (JP-A-7-201331) discloses that in a retainer-type lead-acid battery, if the ratio of the theoretical capacity of the negative electrode material to the theoretical capacity of the positive electrode material is less than 1, lead sulfate tends to accumulate in the negative electrode material. Patent Document 1 further states that by including 0.4 mass% or more of carbon in the negative electrode material, the accumulation of lead sulfate can be suppressed and the lifespan performance can be improved. Patent document 2 (Patent 5083481) discloses that the negative electrode active material (negative electrode material) of a retainer-type lead-acid battery contains a formaldehyde condensate of bisphenol formaldehydes and aminobenzenesulfonic acid, and flaky graphite. Patent document 2 states that the above-mentioned bisphenol condensate is a shrinkage inhibitor for the negative electrode active material and improves charge acceptance compared to lignin, a conventional shrinkage inhibitor. Patent document 2 also states that although the bisphenol condensate reduces hydrogen overpotential, this problem does not occur when the battery is used in PSOC (Partial State of Charge) mode because there is no hydrogen generation. Furthermore, it states that the flaky graphite is a carbon-based conductive material that improves the charge acceptance of the negative electrode active material. Japanese Patent Publication No. 7-201331, Patent No. 5083481 Patent Document 1 proposes incorporating a large amount of carbon into the negative electrode material of a retainer-type lead-acid battery. However, in follow-up tests by the inventors, it was found that incorporating a large amount of carbon into the negative electrode material lowers the hydrogen overpotential and significantly reduces electrolyte loss. Therefore, the inventors investigated ways to suppress the accumulation of lead sulfate in the negative electrode material without increasing the amount of carbon. The inventors then confirmed that bisphenol condensates are effective in preventing the accumulation of lead sulfate in the negative electrode material. However, as described in Patent Document 2, bisphenol condensates have the problem of lowering the hydrogen overpotential of the negative electrode. This is a critical problem in retainer-type lead-acid batteries where water cannot be added. The basic problem of this invention is to suppress the accumulation of lead sulfate on the negative electrode in a lead storage battery such as a retener type in which the electrode material of the negative electrode contains a condensate of bisphenols. Another problem of this invention is to minimize the influence of liquid reduction. This invention relates to a lead storage battery having a separator for holding an electrolytic solution, a positive electrode plate, a negative electrode plate, and an electrolytic cell, wherein the negative electrode material of the negative electrode plate contains a bisphenol condensate, and the theoretical capacity ratio between the negative electrode material and the positive electrode material of the positive electrode plate is 0.85 or more and 1.2 or less. Separators such as retainers may be granular silica or silica gel, etc., but preferably a mat-like separator whose pore diameter is easy to control. Note that the mat-like separator is a mat-like one made of glass fiber or synthetic resin fiber, but it may also be a non-woven fabric. In the electrolytic cell, for example, a compressive force of about 30 to 50 kg / dm2 is applied, and when the median value of the pore diameter of the separator after once holding the electrolytic solution is 3 μm or more and 8 μm or less, a relatively large amount of electrolytic solution can be held even in the negative electrode where the pore diameter is large and it is difficult to hold the electrolytic solution. Therefore, even if liquid reduction occurs, the influence on the characteristics of the storage battery can be reduced. Preferably, the negative electrode material contains 0.05 mass% or more and 0.25 mass% or less of a bisphenol condensate. The main effects of the bisphenol condensate in the negative electrode material are: - suppressing the accumulation of lead sulfate in the negative electrode material; - reducing the hydrogen overvoltage and causing liquid reduction. Note that if the concentration of the bisphenol condensate in the negative electrode material is less than 0.05 mass%, the effect of preventing the accumulation of lead sulfate is insufficient, and if it exceeds 0.25 mass%, liquid reduction becomes remarkable. Particularly preferably, 15 mass% or more of the total amount of the electrolytic solution is held in the negative electrode plate, specifically 15 mass% or more and 25 mass% or less is held. As shown in Tables 1 to 4, compared to lignin, a similar compound used in Patent Document 1, bisphenol condensates can reduce the accumulation of lead sulfate and eliminate the need to include a large amount of carbon. Next, the amount of liquid reduction depends on the theoretical volume ratio of the negative electrode material to the positive electrode material. As shown in Tables 1 to 4, the amount of liquid reduction decreases in the range of 0.85 or more and 1.2 or less, and especially in the range of 0.9 or more and 1.2 or less, and the amount of lead sulfate accumulation also decreases in this range. When the theoretical volume ratio is less than 0.85, the positive electrode material is in excess, so the amount of oxygen gas generated increases, and the oxygen absorption reaction at the negative electrode also increases, which is thought to lead to the accumulation of lead sulfate. Also, when the theoretical volume ratio is greater than 1.2, the negative electrode material is in excess, so liquid reduction tends to progress, and at the same time, the reduction of the negative electrode material is delayed, which is thought to lead to the accumulation of lead sulfate. In this specification, the electrode plates consist of a current collector such as a grid and an electrode material, and the electrode material is sometimes referred to as the active material. The theoretical capacity ratio is the ratio of the theoretical electrical capacity obtained from the lead component Pb in the negative electrode material to the theoretical electrical capacity obtained from the lead component PbO2 in the positive electrode material. If the theoretical capacity of the positive electrode is A and the theoretical capacity of the negative electrode is B, the theoretical capacity ratio is expressed as B / A. To measure the theoretical capacity ratio, for example, a storage battery is disassembled, the positive and negative electrode plates are washed and dried, and the current collector such as a grid and the electrode material are separated. Then, if necessary, components other than the active material, such as carbon and barium sulfate, are removed from the electrode material and the active material is extracted. The amount of lead sulfate in the active material is then measured, the mass if all the active material were lead or lead dioxide is calculated, and the theoretical capacities A and B of the positive and negative electrodes are calculated from the obtained mass, and the theoretical capacity ratio B / A is determined. The theoretical capacity is the theoretical capacity per electrode plate multiplied by the number of electrode plates. In the measurement of theoretical volume ratios, substances containing bisphenol condensates, carbon, barium sulfate, etc., are not included in the active material. Bisphenol condensates are condensates of a bisphenol compound into which a sulfone group has been introduced and formaldehyde, and the bisphenol can be any of bisphenol A, F, S, etc. Bisphenol condensates may have amino groups, etc., but in the examples, those without amino groups are used. Furthermore, this invention does not prevent the use of bisphenol condensates in combination with, for example, 0.2 mass% or less of lignin (lignosulfonic acid). To measure the concentration of bisphenol condensates etc. in the electrode material, the storage battery is disassembled, the negative electrode material is removed from the negative electrode plate, washed with water and dried, and the dry mass of the electrode material is measured. If the electrode material contains lead sulfate, the amount of lead sulfate is measured and converted to lead or lead dioxide. Next, it is immersed in a strong alkaline aqueous solution for 24 hours at, for example, 50°C, and the content of bisphenol condensates is measured from the UV absorption spectrum of the immersion solution, etc. Even after optimizing the theoretical volume ratio between the negative and positive electrodes and optimizing the concentration of the bisphenol condensate, it is difficult to completely eliminate electrolyte loss. Therefore, by optimizing the pore size of the mat-type separator, the required amount of electrolyte is retained on the negative electrode plate even if electrolyte loss occurs. The median pore size of the negative electrode is approximately 2 μm to 3 μm immediately after chemical formation, but increases to 5 μm to 8 μm after use. On the other hand, the median pore size of the positive electrode remains 0.01 μm to 3 μm even after the start of use. In contrast, the mat-type separator often has a pore size of approximately 1-3 μm when compressed, and the pore size is in the order of negative electrode > separator ≥ positive electrode. Considering the capillary action of the electrolyte, the electrolyte is retained in the order of negative electrode < mat-type separator ≤ positive electrode, and the effect of electrolyte loss is greatest at the negative electrode. Therefore, by setting the median pore size of the mat-type separator to 3 μm or more and 8 μm or less, the amount of electrolyte retained at the negative electrode after depletion can be increased, thereby reducing the effect of depletion. It is important to note that the pore size under compressive force within the electrolytic cell is crucial. Furthermore, since pore size has a distribution, the median value of the pore size distribution is used. The median value is the value at which the volume of pores smaller than or equal to the volume of pores larger than or equal to the median value. The pore size under compressed pressure can be measured, for example, as follows: After disassembling the battery and before washing and drying, the pore size and other characteristics are observed using a microscope or similar device. Then, the thickness of the separator after compression is estimated from the thickness of the positive and negative electrodes and the internal dimensions of the battery case. A small piece that fits into a sample tube for the mercury intrusion method is cut from the separator after washing and drying, and compression is applied using a metal or other non-porous material jig to achieve the estimated thickness, and the pore size is measured using the mercury intrusion method. As is clear from Tables 2 and 3, if the median pore size of the mat-type separator is between 3 μm and 8 μm, the negative electrode plate can hold slightly more than 15% of the electrolyte. Therefore, the negative electrode plate is made to hold between 15 mass% and, for example, 25 mass% of the total amount of electrolyte. To measure the amount of electrolyte held, for example, a disassembled battery is separated into the positive electrode, negative electrode, and separator by selecting a portion where the separator is not attached to the positive and negative electrode plates, and the mass of each is measured. The battery should be disassembled in a fully charged state. A fully charged state is defined as the battery being charged until the voltage per cell reaches 2.4V or higher, and within 24 hours of the end of charging. The positive electrode, negative electrode, and separator are washed with water and dried, their mass is measured again, and the value obtained by subtracting this from the mass before washing and drying is considered the amount of electrolyte held. Side view of the main components of the retainer-type lead-acid battery of the embodiment. The following shows an optimal embodiment of the present invention. When implementing the present invention, the embodiment can be appropriately modified in accordance with the common sense of those skilled in the art and the disclosure of the prior art. A negative electrode material containing lead powder, bisphenol condensates (bisphenol A with a sulfone group introduced, or formaldehyde condensates), carbon black, barium sulfate, and synthetic resin fibers was paste-formed with sulfuric acid and filled into a negative electrode current collector made of a Pb-Ca-Sn expanded grid. This paste was then dried and aged to obtain an unformed negative electrode plate. Similarly, a positive electrode material containing lead powder and synthetic resin fibers was paste-formed with sulfuric acid and filled into a positive electrode current collector made of a Pb-Ca-Sn expanded grid. This paste was then dried and aged to obtain an unformed positive electrode plate. Furthermore, by keeping the total thickness of the positive and negative electrode plates constant and adjusting the amount of positive and negative electrode active materials to achieve the desired theoretical capacity ratio, the theoretical capacity ratio between the negative electrode material and the positive electrode material was varied within the range of 0.8-1.25. Four types of mat-shaped separators were prepared, each with a median pore size distribution of 1 μm or more and less than 3 μm under compressed conditions, 3 μm or more and less than 5 μm, 5 μm or more and 8 μm or less, and greater than 8 μm. The pore size was adjusted by changing the density of the glass fibers or synthetic resin fibers used in the separator. A retainer-type lead-acid battery was manufactured by using four negative electrode plates and five positive electrode plates, placing a mat-shaped separator between the plates, and housing them in a battery case under pressure. Sulfuric acid with a specific gravity of 1.25 was added to the battery case to perform a chemical conversion. The structure of the retainer-type lead-acid battery is schematically shown in Figure 1, where 2 is the negative electrode plate, 4 is the positive electrode plate, and 6 is the separator. A negative electrode active material paste was prepared containing lignin instead of bisphenol condensates, and comprising carbon black, barium sulfate, and synthetic resin fibers, with lead powder as the main component. Comparative retainer-type lead-acid batteries (theoretical capacity ratios of 1.0 and 0.85) were manufactured in the same manner otherwise. For each of the three lead-acid batteries, a life cycle test was performed according to JIS D 5302, consisting of a 4-minute discharge at 1CA and a 10-minute charge at a constant voltage of 2.47V (maximum current 1CA). The life cycle count was measured using one of the batteries. Another battery was fully charged and disassembled after 7200 cycles, and the percentage of lead in the negative electrode active material that had been converted to lead sulfate, as well as the amount of electrolyte lost, were measured. If the lifespan was less than 7200 cycles, the measurements were taken at the end of the lifespan. Furthermore, the remaining battery was fully charged and disassembled before the life test, and the percentage of electrolyte held by the positive electrode plate, negative electrode plate, and mat-shaped separator was measured from the mass before and after washing and drying. The results are shown in Tables 1 to 9. By using bisphenol condensates instead of lignin, the accumulation of lead sulfate was significantly reduced. Furthermore, by setting the theoretical capacity ratio of the negative electrode material to the positive electrode material to 0.85 or more and 1.2 or less, preferably 0.9 or more and 1.2 or less, lead sulfate accumulation was suppressed and the amount of electrolyte loss was reduced. In addition, by setting the median pore size of the mat-type separator to 3 μm or more and 8 μm or less, the proportion of electrolyte held by the negative electrode plate could be increased, and the number of cycles until life was significantly increased. Moreover, when the negative electrode plate held 15 mass% or more of the total amount of electrolyte, the number of cycles until life was significantly increased. By using bisphenol condensates, optimizing the theoretical capacity ratio of the negative electrode material to the positive electrode material, and setting the median pore size of the mat-type separator to 3 μm or more and 8 μm or less, a retainer-type lead-acid battery with less lead sulfate accumulation, less electrolyte loss, and a longer number of cycles until life was obtained. In Tables 1 to 4, the bisphenol condensate content was set to 0.2 mass%, but the content is arbitrary. The results in Tables 5 to 11 were obtained in the same manner as in the above examples, except for changing the bisphenol condensate content. From these tables, it can be seen that the bisphenol condensate content in the negative electrode material is preferably 0.05 mass% or more and 0.25 mass% or less. The carbon black content in the negative electrode material is preferably 0.1 mass% to 1.5 mass%, and the type of carbon black is arbitrary. The positive electrode material and negative electrode material may also contain additives other than those shown in the examples, and barium sulfate and synthetic resin fibers are not required. Furthermore, the composition and structure of the current collector are arbitrary, as are the type of lead powder and the conditions for chemical conversion. 2 Negative electrode plate 4 Positive electrode plate 6 Mat-shaped separator

Claims

1. A lead-acid battery with a separator containing the electrolyte solution, anode, cathode, and charge reservoir, in which the negative electrode material of the anode contains a bisphenol condensate mixture and the theoretical capacity ratio of the negative electrode material to the positive electrode material of the anode is 0.85 or higher and not exceeding 1.

22.

2. A lead-acid battery specified in claim 1, which is characterized as a retainer-type lead-acid battery.

3. A lead-acid battery specified in claim 1 or...

2. Specifically, the separator is a non-woven fabric or sheet separator made of glass fibers or synthetic resin fibers.

4. Lead-acid batteries specified in claim 3, specifically, have a center diameter of the pore of the non-woven fabric or sheet separator of 3 µm or greater and not exceeding 8 µm.

5. Lead-acid batteries specified in claims 1-4, specifically, have a negative electrode material containing bisphenol condensate of 0.05 mass% or greater and not exceeding 0.25 mass%. 6.

7. Lead-acid batteries specified in claims 1-5, which are characterized by the presence of bisphenol formaldehyde condensate; 8. Lead-acid batteries specified in claims 1-6, which are characterized by 15 mass% or more of the total volume of electrolyte solution being retained at the negative plate; 9. Lead-acid batteries specified in claims 1-7, which are characterized by 15 mass% or more and not exceeding 25 mass% of the total volume of electrolyte solution being retained at the negative plate; 10. Lead-acid batteries specified in claims 1-5, which are characterized by 15 mass% or more and not exceeding 25 mass% of the total volume of electrolyte solution being retained at the negative plate; 11. Lead-acid batteries specified in claims 1-6, which are characterized by 15 mass% or more and not exceeding 25 mass% of the total volume of electrolyte solution being retained at the negative plate; 12. Lead-acid batteries specified in claims 1-6, which are characterized by 15 mass% or more and not exceeding 25 mass% of the total volume of electrolyte solution being retained at the negative plate; 13. Lead-acid batteries specified in claims 1-6, which are characterized by 15 mass% or more and not exceeding 25 mass% of the total volume of electrolyte solution being retained at the negative plate; 14. Lead-acid batteries specified in claims 1-6, which are characterized by 15 mass% or more and not exceeding 25 mass% of the total volume of electrolyte solution being retained at the negative plate; 15 ...

1. Lead-acid batteries specified in claims 1-8, characterized by a theoretical capacity ratio B / A of 0.9 or higher and not exceeding 1.

210. Lead-acid batteries specified in claims 1-9, characterized by the negative electrode material containing additional carbon.

11. Lead-acid batteries specified in claim 10, characterized by the negative electrode material containing carbon of 0.1 mass% or higher and not exceeding 1.5 mass%.

12. Lead-acid batteries specified in claim 10 or 11, characterized by the carbon being carbon black.