JP5029871B2 - Lead acid battery - Google Patents

Description

  The present invention relates to a lead-acid battery.

  In recent years, the power consumption of an automobile power supply system has increased with the increase in comfortable equipment and the electrification of auxiliary equipment. Therefore, the load on the lead battery for automobiles is increasing year by year, and a higher capacity lead storage battery (hereinafter also simply referred to as a battery) is required and various studies have been made.

  Also, considering the accommodation space in the car, the lead battery for automobiles may have a higher capacity without changing the outer dimensions of the battery (that is, a battery with an improved capacity per unit volume). ) Required.

As a method for improving the capacity per unit volume in a lead storage battery, a method of increasing the number of plates or the amount of active material by narrowing the space between the plates can be considered.
However, according to this method, since the amount of the electrolytic solution per 1 g of the active material is reduced, in the battery having a relatively small amount of the electrolytic solution, the utilization factor of the active material is lowered and the purpose of improving the capacity is sufficiently achieved. Not.

Therefore, in order to solve such a problem, a method of reducing the density of the active material (reducing the density of the active material) is employed (see, for example, Patent Document 1).
JP 2004-199993 A

  According to said method, since the pore volume of an active material increases and the diffusibility of electrolyte solution improves, the utilization factor of an active material can be improved. As a result, it is possible to prevent a decrease in discharge capacity due to a decrease in the amount of electrolyte per gram of active material.

  However, the increase in the pore volume of the active material causes a problem that the bonding force between the active materials is weakened during repeated charging and discharging, and the active material is likely to soften or fall off, resulting in an early life. is there.

  The present invention has been completed based on the above circumstances, and in a battery having a relatively small amount of electrolyte, the electrolyte per 1 g of the fully-charged positive electrode active material without greatly degrading the life performance. The purpose is to suppress a decrease in discharge capacity due to a decrease in the amount (in the present specification, simply referred to as “amount of electrolytic solution per 1 g of active material” or “amount of electrolytic solution”).

  In the present invention, “completely charged state” means charging to the charged state described in JIS D 5301.

As means for achieving the above object, the invention of claim 1 is a lead-acid battery containing 0.85 ml to 1.5 ml of an electrolyte solution per 1 g of a fully charged positive electrode active material, wherein the positive electrode As a raw material of the active material, a mixture of lead powder and a red lead having a lead tanning rate of 20 to 80% by weight is used , and the ratio of the red lead is 10 to 30 with respect to the whole positive electrode active material raw material. It is characterized by the weight percent (meaning “10 wt% or more and 30 wt% or less”) .

In the present invention, the lead tanning rate is a ratio (% by weight) of lead tan in the fired product when lead powder is baked to form lead tan (Pb ₃ O ₄ ), specifically Pb. It is represented by a value obtained by multiplying ₃ O ₄ / (Pb + PbO + Pb ₃ O ₄ ) by 100.

<Invention of Claim 1>
According to the present invention, by using red lead as a raw material for the positive electrode active material, the pore volume of the positive electrode active material is increased and the diffusibility of the electrolytic solution is increased. As a result, the utilization factor of the active material is improved, and the amount of the electrolyte is relatively small (a lead storage battery containing 0.85 ml to 1.5 ml of the electrolyte with respect to 1 g of the fully charged positive electrode active material). Even if it exists, the reduction | decrease of the discharge capacity accompanying the reduction | decrease of the electrolyte solution amount per 1g of active material can be suppressed.

  The reason why the pore volume of the positive electrode active material is increased by the use of lead tan is that there are various theories such as the fact that the lead sulfate crystals produced by the reaction between the electrolyte and the lead tan are large. is there.

  By the way, as a lead, for example, when a lead with a lead tanning rate of 98% by weight (hereinafter referred to as a high lead tanning rate) is used, it is considered to be involved in the bonding between active materials. Since there is little content of lead or lead oxide (PbO), there exists a problem that the bond strength between active materials falls and lifetime performance falls.

  Therefore, according to the present invention, by using a red lead having a lead oxidation rate of 20 to 80% by weight as the red lead (hereinafter also referred to as a low lead randomization rate), during the aging, The lead oxide contained in the lead oxide and the lead oxide remaining in the lead oxide particles having a low lead oxidation rate are fused when dissolved and reprecipitated to improve the bonding between the active material particles.

  As described above, according to the present invention, in a battery having a relatively small amount of electrolytic solution, it is possible to suppress a decrease in discharge capacity due to a decrease in the amount of electrolytic solution per gram of active material without greatly reducing the life performance.

In the present invention, when the ratio of the low lead tanning rate to the entire positive electrode active material raw material is increased, it is possible to suppress a decrease in discharge capacity due to a decrease in the amount of electrolytic solution, but the deterioration in life performance is increased. On the other hand, when the ratio of the low lead oxidation rate is reduced, a decrease in life performance is suppressed, but it is impossible to suppress a decrease in capacity due to a decrease in the amount of electrolyte.

  From the viewpoint of balancing the conflicting factors of suppressing the decrease in capacity due to the decrease in the amount of electrolyte and suppressing the decrease in life performance, in the present invention, the ratio of the low lead tanning rate is 10 to 30% by weight. It is preferable that

  In order to improve the capacity of a conventional battery (conventional example 1 to be described later) containing 1.7 ml of electrolytic solution with respect to 1 g of the positive electrode active material in a fully charged state, the battery of the present invention has The amount of the active material is increased without changing the volume of the tank. Therefore, in the battery of the present invention, the amount of the electrolytic solution for the positive electrode active material 1g in the fully charged state is smaller than that of the battery of Conventional Example 1.

  The amount of the electrolyte of the battery of the present invention is 0.85 ml to 1.5 ml with respect to 1 g of the positive electrode active material in a fully charged state. In the present invention, when the amount of the electrolytic solution is less than 0.85 ml, the discharge capacity is lower than that of the battery of Conventional Example 1, and when the amount of the electrolytic solution exceeds 1.5 ml, the capacity is excessive even if the amount of the electrolytic solution is increased or decreased. This is a range in which the effect of the present invention cannot be exerted because it does not increase or decrease, that is, it is a range in which the capacity decrease due to the decrease in the amount of the electrolytic solution hardly occurs.

  In the present invention, a mixture of lead powder and red lead is used as a raw material for the positive electrode active material for producing the positive electrode plate.

  As lead powder, what contains PbO and metallic lead and obtained by a publicly known method is used, and as lead tan, lead powder containing PbO and metallic lead is fired so as to have a predetermined lead tanning rate. Is used. Furthermore, additives such as organic short fibers are added as necessary.

  As a red lead used in the present invention, a red lead having a lead oxidation rate of 20 to 80% by weight is preferable, and a red lead having a lead oxidation rate of 40 to 60% by weight is more preferable. If the lead tanning rate is less than 20% by weight, it is not possible to suppress a decrease in capacity caused by reducing the amount of the electrolyte compared to the conventional product, and if it exceeds 80% by weight, the life performance of the battery is greatly deteriorated.

  The mixing ratio of the red lead is preferably 10 to 30% by weight with respect to the whole positive electrode active material raw material in consideration of the balance between capacity and battery life performance. If the red lead is less than 10% by weight, the capacity reduction cannot be suppressed, and if it exceeds 30% by weight, the life performance of the battery is lowered.

Examples to which the present invention is specifically applied will be described below.
<Preparation of batteries of Examples 1-38, Conventional Example 1, Comparative Examples 1-35, and Reference Examples 1-6>
In accordance with the conditions described in Tables 1 to 5 (electrolyte amount, lead tanning rate, lead tan addition amount), Examples 1 to 38, Conventional Example 1, Comparative Examples 1 to 35, and Reference Examples 1 to 6 Batteries (hereinafter collectively referred to as test Nos. 1 to 80) were produced by the following procedure.

(1) Preparation of positive electrode plate Lead powder composed of PbO and metal lead produced by a ball mill lead powder production machine was added with a predetermined amount of lead tan of various lead tanning rates to produce mixed lead powder (added) Refer to Table 1 to Table 5 for the lead conversion rate and addition amount of the red lead. Thereafter, water and sulfuric acid were added to the mixed lead powder, and a positive electrode active material paste was prepared using a kneader, except for Comparative Example 2, so that the paste density would be 4.0 g / ml. After filling, a positive electrode plate for a lead storage battery was obtained by aging and drying.

Note that Comparative Example 2 was prepared so that the paste density was 3.8 g / ml by using more water than the other batteries when preparing the paste.
“-” In Tables 1 to 5 indicates that no lead is added.

(2) Production of cell (battery) One positive electrode plate described above and two negative electrode plates produced by a known method were combined through a separator and inserted into a battery case. Next, after pouring a diluted sulfuric acid electrolyte solution having a specific gravity of 1.20 (20 ° C.), the battery was charged in a water bath at 45 ° C. under the conditions of 4.35 A and 6 h, to form a battery case. Thereafter, the specific gravity of the electrolyte was adjusted to 1.28 (20 ° C.) to produce a cell having a nominal capacity of 2V-6Ah.

  Tables 1 to 5 show the amount of the electrolytic solution (ml / g) per gram of the positively charged positive electrode active material used for each cell production. (Described as the amount of electrolyte in the table).

<Battery performance evaluation test>
The following tests were performed on the batteries of Test Nos. 1 to 80 manufactured by the above procedure.
(1) Capacity test The batteries of Test Nos. 1 to 80 were each discharged at a discharge current of 5 A to 1.7 V, the discharge capacity at a temperature of 25 ° C. was measured, and the initial discharge capacity (Ah) was obtained.

  If the result of the capacity test is equal to or less than the result of the capacity test of the battery of test No. 1 (conventional example 1) (4.30 Ah), it is determined that the capacity decrease cannot be suppressed, and if it exceeds 4.30 Ah, the capacity decrease is suppressed. It was judged that.

(2) Life test For the batteries of test Nos. 1 to 80, discharge was performed at 3.2A for 1 hour, charge was performed at 0.8A for 5 hours, and the temperature was measured at 40 ° C. The capacity was measured every 10 cycles. (When the discharge current was 3.2 A, the battery was discharged to 1.7 V). When the measured capacity fell below 2.4 Ah, the life was judged to be the life cycle number.

  When the result of the life test was equal to or greater than the number of life test cycles (140) of test No1, it was determined that the life reduction could be suppressed, and when it was less than 140, it was determined that the life reduction could not be suppressed.

<Test results and discussion>
(1) Conventional battery (conventional example 1), battery in which the amount of electrolyte of the battery in conventional example 1 is reduced (comparative example 1), battery in which the paste density of the battery in comparative example 1 is reduced (comparative example 2), lead In order to compare the performances of the battery (Comparative Example 3) to which the lead oxidation rate was 98% by weight and the battery to which the lead oxidation rate was added 50% by weight (Example 1), The results of the performance test are shown in Table 1.

  From Table 1, the capacity of the battery of Comparative Example 1 having a smaller amount of electrolyte than that of Conventional Example 1 is decreased, and the capacity of the batteries of Comparative Examples 2 and 3 is reduced due to the decrease in the amount of electrolyte. However, it was found that the life performance was lowered, and in the battery of Example 1, it was possible to suppress a decrease in capacity due to a decrease in the amount of electrolyte without reducing the life performance.

  In Example 1, the capacity reduction accompanying the decrease in the amount of the electrolytic solution was able to be suppressed because the pore volume of the active material was increased and the diffusibility of the electrolytic solution was improved by the addition of red lead. This is probably because the utilization rate of the substance was improved.

  In Example 1, there was no decrease in the life performance because the amount of lead oxide remained in the lead-tan particles having a lead-tanning rate of 50% by weight as compared with the lead-tan having a high lead-tanning rate. This is thought to be because the lead oxide and the lead oxide contained in the lead powder particles were fused when dissolved and reprecipitated during aging, and the connectivity between the active material particles was improved.

  (2) In order to examine the lead tanning rate of the added lead tan, the results of the performance test of the lead-free battery and the batteries with various lead tan addition rates are shown for each electrolyte amount. It was shown in 2.

  Further, the results shown in Table 2 are graphed and shown in FIG. The left graph in FIG. 1 is a graph in which the horizontal axis represents the lead oxidation rate (% by weight), and the vertical axis represents the discharge capacity (Ah). In the right graph, the horizontal axis represents the lead oxidation rate (% by weight). It is a graph which makes a life cycle a vertical axis | shaft. In FIG. 1, □, ◆, and △ indicate battery data in which the amount of the electrolytic solution per 1 g of the fully charged positive electrode active material is 1.5 ml / g, 1.3 ml / g, and 0.85 ml / g, respectively. .

From Table 2 and FIG. 1, the following was found.
In the lead-free battery (Comparative Examples 1, 6, and 10) and the battery to which the lead-tanning rate was less than 20% by weight (Comparative Examples 4, 7, and 11), the amount of the electrolyte was changed to the conventional amount. It was not possible to suppress a decrease in capacity due to the fact that the amount of electrolyte was smaller than that of the battery.

  In the battery (Comparative Examples 3, 5, 8, 9, 12, 13) to which the lead oxidation rate exceeds 80% by weight, the capacity decrease due to the decrease in the amount of the electrolyte can be suppressed, but the lifetime Performance declined.

  In batteries (Examples 1 to 15) to which a lead oxidation rate of 20% to 80% by weight is added, suppress the capacity reduction accompanying the decrease in the amount of electrolyte without significantly reducing the life performance. I found out that

  From the above, in the present invention, it is considered that the lead oxidation rate of the added red lead is preferably 20% by weight to 80% by weight.

  (3) In order to examine the amount of electrolyte contained, the performance test results of batteries with various amounts of electrolyte for each lead tanning rate are shown in Table 3 for batteries to which 20% by weight of red lead was added. . The results of the performance test were also shown for the lead-free battery.

  In addition, the results shown in Table 3 are graphed and shown in FIG. The graph on the left side of FIG. 2 is a graph in which the horizontal axis is the amount of electrolyte solution per gram of the positive electrode active material in a fully charged state (ml / g), and the vertical axis is the discharge capacity (Ah). 4 is a graph in which the horizontal axis represents the amount of the electrolyte solution per gram of the fully charged positive electrode active material (ml / g), and the vertical axis represents the life cycle. In FIG. 2, □, ♦, Δ, and ◯ indicate data of a battery to which 80% by weight, 50% by weight, and 20% by weight of lead tanning are added, and data of a battery to which no lead tan is added, respectively.

From Table 3 and FIG. 2, the following was found.
When the amount of the electrolyte exceeds 1.5 ml with respect to 1 g of the fully charged positive electrode active material, the capacity does not increase or decrease much even if the amount of the electrolyte increases or decreases, and the amount of the electrolyte becomes 1 g of the fully charged positive electrode active material. On the other hand, in batteries (Comparative Examples 16, 18, 20, and 22) less than 0.85 ml, the capacity reduction due to the decrease in the amount of the electrolyte could not be sufficiently suppressed.

  Batteries of 0.85 ml to 1.5 ml with respect to 1 g of the positive electrode active material in a fully charged state and added with red lead (Examples 1, 2, 5, 6, 9 to 11, 14 to In 18), it was possible to suppress a decrease in capacity due to a decrease in the amount of electrolyte without significantly reducing the life performance.

  From the above, in the present invention, it is considered that the amount of the electrolyte is preferably 0.85 ml to 1.50 ml with respect to 1 g of the fully charged positive electrode active material.

  The batteries of Comparative Examples 17, 19, and 21 have a higher capacity than the battery of Conventional Example 1 and the life performance is not deteriorated, but the amount of the electrolytic solution relative to 1 g of the positive electrode active material is the same as that of Conventional Example 1. This is not included in the present invention because it falls within the range of the amount of electrolytic solution that does not cause a decrease in capacity due to the decrease in the amount of electrolytic solution, which is the gist of the present invention.

  (4) In order to examine the amount of added lead, the results of performance tests of batteries with different amounts of added lead (lead oxidation rate 50% by weight) are shown in Table 4 for each amount of electrolytic solution. Table 5 shows the results of the performance test of the battery to which 35% by weight of the red lead is added.

  The results of Table 4 are graphed and shown in FIG. The graph on the left side of FIG. 3 is a graph in which the horizontal axis is the amount of added lead (wt%) and the vertical axis is the discharge capacity (Ah), and the graph on the right is the amount of added lead (wt%). It is a graph which makes a life cycle a vertical axis | shaft. In FIG. 3, □, ◇, and Δ indicate data of the amount of the electrolytic solution per gram of the positive electrode active material in a fully charged state, 1.5 ml / g, 1.3 ml / g, and 0.85 ml / g, respectively.

  From Table 4 and FIG. 3, when the amount of added lead is less than 10% by weight (Comparative Examples 1, 23, 26, 29), it is impossible to suppress a decrease in capacity due to a decrease in the amount of electrolytic solution. It was found that when the added amount of Dan exceeded 30% by weight (Comparative Examples 24, 25, 27, 28, 30, 31), it was not possible to suppress the life reduction.

  In addition, when the amount of added lead is 10 to 30% by weight (Examples 1, 9, 14, 19 to 30), the decrease in capacity due to the decrease in the amount of electrolytic solution is suppressed without significantly reducing the life performance. I found out that

From Table 5, when the amount of added lead is 35% by weight, the batteries having the lead oxidation rate of 20% by weight and 50% by weight and the electrolyte amount of 0.85 to 1.50 ml (Examples 31 to 38). ), It was possible to suppress a decrease in capacity due to a decrease in the amount of the electrolyte without deteriorating the life performance. However, the batteries with a lead tanning rate of 80% by weight (Reference Examples 1 to 6) have a long life performance. It turns out that it falls.
That is, it was found that when the amount of added lead is 35% by weight, the life performance may be reduced depending on the rate of lead oxidation of the used red lead.

  As mentioned above, it is thought that a preferable range is about 10 to 30 weight% about the addition amount of a red lead.

  In addition, 80 kinds of batteries were prepared and performance evaluation tests were conducted in the same manner as described above for those in which the specific gravity of the electrolyte was changed within the range of 1.28 ± 0.10 (20 ° C.). showed that.

<Summary>
According to the present invention, as a raw material for the positive electrode active material, by using a mixture of lead powder and lead tan having a lead tanning rate of 20 to 80% by weight, a fully charged state can be obtained without greatly reducing the life performance. The capacity | capacitance reduction accompanying the reduction | decrease in the quantity of the electrolyte solution with respect to 1g of positive electrode active materials of can be suppressed.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) The lead oxidation rate, the addition amount, and the amount of the electrolytic solution per 1 g of the active material are not limited to those described in Tables 1 to 5. For example, the lead tanning rate may be 25% by weight or 45% by weight, the added amount may be 15% by weight or 25% by weight, or the amount of the electrolyte may be 1.40 ml or 1.20 ml.

A graph showing the relationship between the lead tanning rate (wt%) and the discharge capacity (Ah) of the added lead tan (left), and a graph showing the relationship between the lead tanning rate (wt%) and the life cycle (right) ) A graph (left) showing the relationship between the amount (ml / g) of electrolyte solution per gram of positive electrode active material in a fully charged state and the discharge capacity (Ah), and the amount of electrolyte solution per gram of positive electrode active material in a fully charged state Graph (right) showing the relationship between (ml / g) and life cycle Graph (left) showing the relationship between the amount of added lead (wt%) and discharge capacity (Ah) (left) and graph showing the relationship between the amount of added lead (wt%) and life cycle (right)

Claims (1)

A lead storage battery containing 0.85 ml to 1.5 ml of an electrolyte solution per 1 g of a fully charged positive electrode active material,
As a raw material of the positive electrode active material, a mixture of lead powder and a red lead having a lead tanning rate of 20 to 80% by weight is used , and the ratio of the red lead is 10 with respect to the whole positive active material. Lead acid battery characterized by being -30% by weight .

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