JP2009129725A - Lead storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that the charging/discharging performance of a lead storage battery is deteriorated in a severe usage form like an idling stop vehicle. <P>SOLUTION: A filling method of a negative electrode paste is changed to make the charging/discharging reaction effective through proper composition of lignin, carbon quantity and barium sulfate quantity for an additive agent. Further, without changing the total quantity and types of lignin, carbon and barium sulfate, charging accepting performance can be improved without causing deterioration in the high-efficiency discharging performance. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an improvement in the performance of a negative electrode plate of a lead storage battery.

  The electrode plate constituting the lead storage battery is prepared by mixing lead powder with various additives, mixing dilute sulfuric acid and water to produce a lead paste (hereinafter abbreviated as paste), and using the paste as a current collector made of lead alloy. Fill to make. The electrode plate includes a positive electrode and a negative electrode. In particular, in the negative electrode, several kinds of additives have been conventionally added to the paste in order to improve performance. Among these, organic expanders such as lignin have a function of suppressing the aggregation of metallic lead generated during charging by being adsorbed on the surface of the active material. Carbon is added to the negative electrode paste in order to improve the conductivity of the negative electrode plate, including non-conductive lead sulfate produced during discharge. In addition, barium sulfate acts as a lead nucleus of lead sulfate generated during discharge. Therefore, it is known that as the amount of barium sulfate added is larger and the particle size is smaller, the particle size of lead sulfate is smaller and the effect of refining the active material is enhanced.

  However, since the active material of lead-acid batteries is lead and sulfuric acid, which is an electrolytic solution, additives such as lignin, carbon, and barium sulfate are contained in the electrode plate, and the chemical reaction between lead and sulfuric acid and the electrochemical reaction are carried out. It will interfere. Therefore, if an excessive amount of additive is added, the input / output performance of the lead-acid battery is degraded. Therefore, optimization of the additive amount is an important issue. Generally, the amount of lignin and carbon added to the negative electrode paste is as small as about 0.2% by weight with respect to the lead powder, but it has adsorption sites such as phenolic hydroxyl groups and carboxyl groups, so it adsorbs to the lead particles as the active material. Battery performance is improved, but there is also a decrease in performance.

  On the other hand, in recent years, lead-acid batteries are often used in a form of use such as a so-called idling stop vehicle in which the engine is started and stopped repeatedly. In such a state, the lead-acid batteries are always in a state of insufficient chargeability. Therefore, it is known that lead storage batteries have a short life because lead sulfate, which is a negative electrode active material, becomes coarser, so-called sulfation proceeds. In order to prevent this, attempts have been made such as Patent Document 1 to extend the charge acceptance performance, high rate discharge performance, and cycle life performance of lead-acid batteries, but further improvement in charge acceptance performance, high rate discharge performance. There is a need for lead-acid batteries that do not degrade.

Japanese Patent Laid-Open No. 2003-142086

  In the initial chemical reaction during charging and discharging, lead on the electrode plate reacts with sulfuric acid in the electrolyte, which is also the active material. Therefore, the larger the active material specific surface area of the electrode plate surface, the higher the charge / discharge reactivity. improves. However, if the specific surface area of the active material is large, non-conductive lead sulfate progresses at an early stage when discharging, resulting in a decrease in high rate discharge performance. Further, in order to improve the high rate discharge sustainability, the progress of lead sulfate formation is suppressed, and the initial charge / discharge reactivity is lowered. In general, charge acceptance performance and high rate discharge performance are contradictory performances. In a severe use environment such as the idling stop vehicle described above, a significant improvement in these two performances is required.

  In the present invention, in view of the above matters, the lignin and carbon in the negative electrode plate are present in the negative electrode plate inner layer portion more than the negative electrode plate outer layer portion, and the barium sulfate is present in the negative electrode plate outer layer portion more than the negative electrode plate inner layer portion. To improve the charge acceptance performance, and further improve the high rate discharge performance.

  In the present invention, it is effective only by adjusting the additive amount of the inner layer part and the outer layer part of the negative electrode plate without changing the kind of additive and without increasing the total amount of additive in the negative electrode plate. It is possible to advance the charge / discharge reaction and improve the input performance without degrading the high rate discharge performance.

  Hereinafter, the present invention will be described in detail with reference to specific examples. However, the present invention is not limited to the examples unless it exceeds the gist of the invention.

Examples of the present invention will be described below.
(Preparation of negative electrode plate)
Lignin, carbon and barium sulfate were added to the lead powder and dry mixed. Next, 13% by weight dilute sulfuric acid (specific gravity 1.26 / 20 ° C conversion) with respect to the lead powder and 12% by weight water with respect to the lead powder were kneaded to prepare a negative electrode paste.

  The addition rates of lignin, carbon and barium sulfate are shown in Table 1. The addition rate is% by weight with respect to the lead powder. The conventional product corresponds to the paste 13. In addition, although lignin and carbon show a total value, these compounding ratios can be adjusted arbitrarily and the following effects are the same.

  Paste 1 to paste 25 in Table 1 were filled into an expanded current collector (Ca: 0.05%, Sn: 0.5%, balance: Pb) having a thickness of 0.6 mm, and a total of 25 combinations were made as shown in Table 2. The negative electrode plate of specification was produced. Here, the negative electrode plate inner layer portion described here refers to a portion where the lattice is first uniformly filled with a normal half filling amount, and is semi-dried in this state, and the remaining half filling amount paste is applied to the negative electrode plate. It was filled uniformly from the front and back of the. The portion filled at this time is defined as the negative electrode plate outer layer portion.

  No. in Table 2 Since 13 is a conventional product, there is no difference between the inner layer portion and the outer layer portion of the negative electrode plate. Further, the total amount of additives in each paste was adjusted to be the same as that of the conventional product.

  According to a normal method, the negative electrode plate of 25 specifications was left to mature for 18 hours in an atmosphere of 50 ° C. and 95% humidity, and then dried in an atmosphere of 50 ° C. to obtain an unformed negative electrode plate.

(Preparation of positive electrode plate)
The positive electrode plate is dry-mixed with 0.01% by weight of lead powder and lead fiber, 13% by weight of dilute sulfuric acid (specific gravity 1.26 / 20 ° C conversion) and lead powder. A positive electrode paste was prepared by kneading 12% by weight of water. This positive electrode paste was filled in a positive electrode current collector (Ca: 0.05%, Sn: 0.5%, balance: Pb) made of a cast grid, and 18 hours in an atmosphere of a temperature of 50 ° C. and a humidity of 95%. After standing and aging, it was dried in an atmosphere at a temperature of 50 ° C. to obtain an unformed positive electrode plate.
(Battery assembly and formation)
An electrode plate group composed of one unformed negative electrode plate and two unformed positive electrode plates was produced via a glass fiber separator, and this was inserted into a battery case to assemble a 2V single plate battery. Dilute sulfuric acid (specific gravity 1.28 / 20 ° C conversion) was poured into this battery, and after 15 hours of chemical formation at an electric current of 1.0 A, the electrolyte was discharged, and the specific gravity 1.28 (20 ° C conversion) was diluted again. Completed by injecting sulfuric acid.
(Evaluation methods)
About each said 2V single plate battery, the input performance and the high rate discharge performance were measured. The input performance was measured when the state of charge (SOC) of the battery was 90%, that is, when the battery capacity was discharged from 10% of the fully charged state and the battery was charged at a constant voltage of 2.33 V for the 5th second . The larger the current value at this time, the higher the initial charge capacity, and the better the input performance. Moreover, the high rate discharge performance measured the discharge duration until the 5th-second voltage and battery voltage reached 1.0V at the time of discharging at 5 C current.

  As an evaluation method, it is difficult to compare the two indexes of input performance and high-rate discharge performance. Therefore, the input performance of the conventional product is set to 100 and the output performance is set to 100. . The results are shown in Table 3.

  No. It is No. that exceeds the numerical value 200 of the conventional product of No. 13. 17. In this negative electrode plate, the specification of the inner layer portion is paste 17 and the specification of the outer layer portion is paste 9. Thus, the ratio of the lignin and carbon addition amount in the negative electrode plate inner layer paste to the lignin and carbon addition amount in the negative electrode outer layer portion is 3: 1, and the barium sulfate addition amount in the negative electrode plate inner layer paste and It can be seen that when the ratio of the amount of barium sulfate added to the outer layer portion of the negative electrode plate is 1: 3, the input performance is improved without deterioration of the high rate discharge performance.

  The three-layer negative electrode active material paste (inner layer 1, outer layer 2) of the present invention improves charge acceptance and output performance without changing the total amount of negative electrode additive and without using new lignin and carbon. Is possible. As a result of further trials, similar results were obtained regardless of the types of lignin and carbon. Therefore, in the present invention, an appropriate blending method of the negative electrode additive can be proposed, and it is suitable for a severe form of use of a lead storage battery such as an idling stop vehicle.

Claims (2)

   In a lead storage battery using a negative electrode plate prepared by filling a lead alloy current collector with a lead paste, lignin and carbon in the negative electrode plate are present more in the negative electrode plate inner layer than in the negative electrode plate outer layer, and barium sulfate is A lead-acid battery using a negative electrode plate that is present more in the outer layer part of the negative electrode plate than in the inner layer part of the negative electrode plate.   The ratio of the lignin and carbon addition amount in the negative electrode plate inner layer paste to the lignin and carbon addition amount in the negative electrode outer layer portion is 3: 1, and the barium sulfate addition amount and negative electrode plate in the negative electrode inner layer paste The lead acid battery according to claim 1, wherein the ratio of the amount of barium sulfate added to the outer layer is 1: 3.