JP2008130516A - Liquid lead-acid storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid lead-acid storage battery in which permeation short circuit due to an over-discharge continuation is suppressed by controlling an amount of positive/negative electrode active material and a sulfuric acid amount in an electrolytic solution at an appropriate ratio, and a liquid lead-acid storage battery in which life characteristics are improved. <P>SOLUTION: In the liquid lead-acid storage battery composed by housing in a battery box a group of electrode plates in which a positive electrode plate and a negative electrode plate composed by filling an active material paste into a substrate consisting of a lead alloy are laminated alternately via a separator, and by injecting an abundant amount of liquid so that an electrolytic liquid exists in which an abundant amount of the electrolytic liquid is liberated in the battery box, when the total sum of the positive active material amount filled into the positive electrode plate and the negative active material amount filled into the negative electrode plate is expressed by A, and sulfuric acid amount contained in the electrolytic liquid is B (at fully charged, initial condition in which deterioration is not proceeding), and when the ratio (B/A) between the total sum A of the filled amount and the sulfur amount B is expressed by Y, and the positive electrode active material density is X [g/cm<SP>3</SP>], then -0.125X+0.8≤Y (wherein 3.8≤X≤4.6) is given. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a liquid lead-acid battery including a large amount of free electrolytic solution in which the amount of positive and negative electrode active materials and the amount of sulfuric acid in the electrolytic solution are set to an appropriate ratio.

Lead-acid batteries can be broadly classified into liquid-type lead-acid batteries that require maintenance such as replenishment and control valve-type lead-acid batteries that do not require replenishment. And it has a long history along with alkaline storage batteries typified by nickel-cadmium batteries, and it occupies the mainstream of storage batteries because of its high reliability due to its stable performance as well as its low cost. It is widely used as a power source for operation, a power source for movement used in small electronic devices and electric vehicles, or a stationary power source for backup that operates in the event of a power failure of a power source such as a computer.

In recent years, the environment surrounding lead-acid batteries used in automobiles, that is, liquid lead-acid batteries for automobiles, has become increasingly severe. The reasons for this are an increase in comfort equipment, advanced electronic control of the entire vehicle, and further reduction in size and weight of the battery. The load on the liquid lead-acid battery for automobiles used in automobiles continues to increase. . However, in liquid lead-acid batteries for automobiles, the initial characteristics are rather emphasized, and the positive electrode active material density is used as 3.8 g / cm ³ or less.

In addition, automobiles in urban areas tend to be used only for holidays, repeated stop-and-go due to traffic jams, and short-distance use due to the development of transportation networks such as trains and buses. Accordingly, the liquid lead-acid battery for automobiles is left for a long time in a state where it is not sufficiently charged, and is equipped with many electrical components, so that it is easily used in an overdischarged state due to an increase in dark current.

When the liquid lead-acid battery for automobiles is used while continuing the overdischarge state, the metallic lead derived from the electrode plate crystal grows inside the separator. That is, when sulfate ions in the electrolytic solution are consumed at the end of discharge and the electrolytic solution is close to pure water, the solubility of lead ions increases, and lead sulfate produced in the positive electrode and the negative electrode is partially dissolved. Thereafter, when charged, lead ions in the electrolytic solution are reduced at the negative electrode to deposit metallic lead, which grows on the surface of the negative electrode plate to form needle crystals. The needle-like crystal of the metal lead is generally called “dendrites”. However, when the dendrites grow, they reach the other electrode plate and are short-circuited, so that subsequent charge / discharge cannot be performed.

As a method for suppressing the dendrite of a lead-acid battery, when the positive electrode active material amount is P, the negative electrode active material amount is N, and the sulfuric acid amount contained in the electrolyte is E, the positive electrode active material and the negative electrode active material It has been proposed that E / (P + N), which is the ratio of the amount of sulfuric acid to P + N, which is the combined mass of substances, be 0.25 to 0.35 (Patent Document 1).

JP 2004-14283 A

The method described in Patent Document 1 relates to a control valve-type lead-acid battery, that is, a method in which the electrolyte is impregnated and held in the electrode plate group, or a method in which a small amount of electrolyte is provided. It was found that when applied to a liquid lead-acid battery, dent light short-circuiting cannot always be prevented.

In order to satisfy the current market, the inventors have conducted various studies on whether there is a method for suppressing the dendrite short and improving the life characteristics of the lead-acid battery.
In the liquid lead-acid battery, when the ratio (B / A) of the total amount A and the sulfuric acid amount B of the positive and negative electrode active materials is Y and the positive electrode active material density is X [g / cm ³ ], It has been found that it is preferable to define 0.125X + 0.8 ≦ Y (where 3.8 ≦ X ≦ 4.6), and further studies have been made to complete the present invention.
As described above, the present invention provides a liquid lead-acid battery that suppresses short-circuiting due to the formation of dendrites that are left over-discharged in a liquid lead-acid battery, improves life characteristics, and is substantially equivalent to the conventional initial capacity. With the goal.

The present invention accommodates an electrode plate group in which a positive electrode plate and a negative electrode plate formed by filling a substrate made of a lead alloy with an active material paste alternately with a separator interposed therebetween in a battery case. In a liquid lead acid battery in which a large amount of electrolyte is injected so that a large amount of electrolyte is released, the amount of positive electrode active material charged in the positive electrode plate and the amount of negative electrode active material charged in the negative electrode plate The total is A, the amount of sulfuric acid contained in the electrolyte is B (completely charged initial state where deterioration is not progressing), the ratio (B / A) of the total A to the amount of sulfuric acid B (B / A) is Y, the positive electrode When the active material density is X [g / cm ³ ], the liquid lead-acid battery satisfies the relationship of −0.125X + 0.8 ≦ Y (however, 3.8 ≦ X ≦ 4.6) .

As described above, when the positive electrode active material density X [g / cm ³ ] is set to 3.8 ≦ X ≦ 4.6 and −0.125X + 0.8 ≦ Y, dendrite is generated due to overdischarge. It is possible to prevent the short circuit by suppressing the above, improve the life of the liquid lead acid battery, and provide a liquid lead acid battery substantially equivalent to the conventional initial capacity.
Both the positive electrode active material and the negative electrode active material react with sulfuric acid in the electrolytic solution due to overdischarge to produce a large amount of lead sulfate. By setting the ratio Y to −0.125X + 0.8 ≦ Y, sulfuric acid in the electrolytic solution Since sufficient ions remain, the state does not become neutral water, and dendrite generation during charging can be suppressed. However, when the ratio Y is −0.125X + 0.8 ≧ Y, the sulfuric acid in the electrolytic solution is almost consumed by the lead sulfate generated in the positive and negative electrode plates during overdischarge, so the electrolytic solution is like neutral water. It becomes a state. As a result, the solubility of lead sulfate increases and a large amount of dissociated lead ions penetrate into the electrolyte, and when energized, needle-like dendrites are formed on the negative electrode plate and eventually grow and penetrate the separator. A short circuit occurs upon reaching the positive electrode.

Furthermore, in the present invention, in view of the ever-increasing load on the liquid lead-acid battery for automobiles, the positive electrode active material density was increased in order to improve the life characteristics. Normally, it is said that increasing the positive electrode active material density decreases the initial capacity, but improves the life characteristics. The cause of the decrease in the initial capacity is that the volume of the electrolyte present in the electrode plate is reduced by decreasing the pore volume by increasing the active material density, and the liquid diffusibility inside the electrode plate is reduced. It is possible. In addition, the life characteristics are improved because the active material amount is relatively increased by increasing the active material density, or the active material is structurally strengthened by increasing the bonding force between the active material particles. This is thought to be because the softening of the active material is suppressed.

However, within the range of the ratio Y of the present invention and the positive electrode active material density X, the initial capacity of the liquid lead-acid battery does not significantly decrease until the positive electrode active material density is 4.6 g / cm ³ . Moreover, when the positive electrode active material density was less than 3.8 g / cm ³ , the initial capacity of the liquid lead acid battery was improved, but no improvement in the life characteristics was observed.

Therefore, in the present invention, when the ratio (B / A) of the total positive / negative active material filling amount A to the sulfuric acid amount B is Y and the positive electrode active material density is X [g / cm ³ ], −0.125X + 0. By setting 8 ≦ Y (however, 3.8 ≦ X ≦ 4.6), dendrite generation due to overdischarge is suppressed to prevent a short circuit, and a high rate discharge characteristic has a positive electrode active material density of 3.8 g / cm. ^It is substantially the same as the case of less than ³ , and it aims at improving a lifetime characteristic.

In the present invention, when the ratio (B / A) of the total amount A and the sulfuric acid amount B of the positive and negative active material filling amounts is Y and the positive electrode active material density is X [g / cm ³ ], −0.125X + 0. By setting 8 ≦ Y (however, 3.8 ≦ X ≦ 4.6), it is possible to suppress the generation of dendrites due to overdischarge and prevent a short circuit, but the ratio Y is Y> −0.125X. In the case of +0.9 (however, 3.8 ≦ X ≦ 4.6), it is necessary to make the electrolytic solution have a high specific gravity or increase the amount of the electrolytic solution. However, when the specific gravity is increased, the corrosion rate of the lead alloy grid, which is the current collector, will deteriorate and the high rate discharge characteristics will decrease due to the decrease in conductivity. If the amount of liquid is increased, the amount of electrolyte will increase more than necessary. Not only that, the battery is bigger and heavier than necessary. Moreover, although it can respond also by adjusting the amount of negative electrode active materials, there exists a possibility of causing the malfunction that the battery capacity corresponding to a positive electrode capacity cannot be obtained. Therefore, when the ratio (B / A) of the total amount A of the positive and negative active materials and the amount B of sulfuric acid (B / A) is Y and the positive electrode active material density is X [g / cm ³ ], −0.125X + 0.8 ≦ Y ≦ −0.125X + 0.9 (however, 3.8 ≦ X ≦ 4.6) is preferable.

The present invention makes it possible to prevent the generation of dendrite due to overdischarge and prevent a short circuit by adjusting the amount of positive and negative electrode active materials of the liquid lead-acid battery and the amount of sulfuric acid in the electrolyte to an appropriate ratio. Further, it is possible to further improve the life characteristics and have an industrially excellent effect.

An electrode plate group in which a positive electrode plate and a negative electrode plate formed by filling a lead alloy substrate with an active material paste are alternately stacked via a separator is housed in a battery case, and a large amount of electrolyte is contained in the battery case. In the liquid lead-acid battery in which a large amount of electrolyte is injected so that a free electrolyte exists, the total amount of the positive electrode active material charged in the positive electrode plate and the negative electrode active material amount charged in the negative electrode plate is A, If the amount of sulfuric acid contained in the electrolyte solution is B (completely charged and the initial state is not deteriorated), the ratio of the total amount A to the amount of sulfuric acid B (B / A) is Y, the positive electrode active material density When X is [g / cm ³ ], -0.125X + 0.8 ≦ Y (however, 3.8 ≦ X ≦ 4.6) prevents dendrite generation due to overdischarge and prevents short circuit. and, and if the initial characteristic is less than the positive active material density 3.8 g / cm ³ and at substantially the same, further lifetime There is provided a liquid type lead-acid battery with improved resistance.

First, a positive electrode active material prepared by a known method was filled in a substrate made of a lead alloy, and aged and dried to prepare a positive electrode non-formed electrode plate. Similarly, a negative electrode active material prepared by a known method was filled in a substrate made of a lead alloy, and aged and dried to prepare a negative electrode non-formed electrode plate. Next, an electrode plate group was formed in which a plurality of positive electrode unformed electrode plates and negative electrode unformed electrode plates were alternately laminated via a polyethylene separator. Then, the electrode tabs of the same polarity formed so as to protrude from the respective electrode plates were welded together, the electrode plate ears and the strap were welded, and stored in the battery case. Then, the battery case is provided with a battery case lid, diluted sulfuric acid having a specific gravity of 1.260 (20 ° C.) is injected from the injection port provided on the battery case lid, and the battery case is formed in a water tank adjusted to 55 ° C. 10 liquid lead-acid batteries for automobiles were produced (lead-acid battery 1).
The positive electrode active material density X [g / cm ³ ] of the positive electrode unformed electrode plate was set to X = 4.0.
In addition, the total amount of the positive electrode active material filled in the positive electrode plate and the amount of the negative electrode active material filled in the negative electrode plate is A, and the amount of sulfuric acid contained in the electrolyte solution is B (completely charged and the initial deterioration is not progressing) State), the ratio of the total amount A and the amount of sulfuric acid B was adjusted by the amount of sulfuric acid so that Y = B / A = 0.31.

Moreover, as described in Table 1, the positive electrode active material density X [g / cm ³ ] was set to X = 4.0 or 4.4, and the ratio Y was changed, respectively. Ten various liquid lead acid batteries were produced (lead acid batteries 2 to 23).

And about the liquid lead acid battery (storage batteries 1-23) for various produced automobiles, the penetration short circuit test was done in order to confirm the ease of generating the dendrite after overdischarge leaving. In the penetration short circuit test, first, discharge was performed at a discharge current of 0.2 C (5 hour rate current) in an environment of 25 ° C. to a discharge end voltage of 10.5 V, and then a 12 V-10 W lamp was connected in an environment of 60 ° C. The state was left for 14 days (discharge), and the lamp was removed and left for 14 days in a 60 ° C. environment (self-discharge). And after performing constant voltage charge for 4 hours in an environment of 60 ° C., after measuring the voltage and confirming the presence or absence of permeation short circuit, various liquid lead acid batteries for automobiles were disassembled and lead permeation short circuit to the separator The presence or absence of was confirmed visually.
Table 1 shows the filling amount and density of the positive electrode active material and the total amount A of the positive electrode active material and the negative electrode active material, the sulfuric acid amount B, the positive electrode active material and the negative electrode active material of the various liquid lead-acid batteries for automobiles. The ratio of the filling amount, the ratio Y = B / A, and the presence or absence of an osmotic short circuit are shown.

As shown in Table 1, the positive electrode active material density X [g / cm ³ ] is X = 4.0, and the ratio Y between the total amount A of the positive and negative electrode active materials and the sulfuric acid amount B is 0.30 or more (lead In the case of storage batteries 1 to 10), no osmotic short circuit is observed, and the positive electrode active material density X [g / cm ³ ] is X = 4.4, and the total amount A and sulfuric acid amount B of the positive and negative electrode active materials When the ratio Y was 0.25 or more (lead batteries 14 to 20), no permeation short circuit was observed.
However, the positive electrode active material density X [g / cm ³ ] is X = 4.0, and the ratio Y between the total amount A and the sulfuric acid amount B of the positive and negative electrode active materials is less than 0.30 (lead batteries 11 to 13). ), And the positive electrode active material density X [g / cm ³ ] is X = 4.4, and the ratio Y between the total amount A and the amount of sulfuric acid B of the positive and negative electrode active materials is less than 0.25 (lead storage battery 21 In the case of ˜23), the occurrence of an infiltration short circuit was confirmed. This is because the sulfuric acid in the electrolytic solution is almost consumed by the lead sulfate generated on the positive and negative electrode plates during overdischarge, and the electrolytic solution is neutral water. As the lead sulfate solubility increased and a large amount of dissociated lead ions floated in the electrolyte and became energized, needle-shaped dendrites grew on the negative electrode plate, penetrated the separator, and reached the positive electrode This is considered to be the cause.

FIG. 1 shows the relationship between the positive electrode active material density X [g / cm ³ ] and the ratio Y based on Table 1.
Here, the approximated curve of Y = −0.125X + 0.8 shown in the figure shows an osmotic short circuit when the positive electrode active material density X [g / cm ³ ] is X = 4.0 and X = 4.4. It is calculated by the minimum value of the ratio Y that was not obtained. As shown in FIG. 1, when the positive electrode active material density X [g / cm ³ ] is −0.125X + 0.8 ≦ Y when X = 4.0 and X = 4.4, it is suggested that no permeation short circuit occurs. When −0.125X + 0.8 ≧ Y, a penetration short circuit occurs.
Note that the approximate curve of Y = −0.125X + 0.9 shown in the figure shows a preferable range of the present invention. Osmotic short-circuiting is not observed when the ratio Y is −0.125X + 0.8 ≦ Y. However, in the lead storage battery 8 and the lead storage battery 18 in Table 1, the amount of the electrolyte is increased more than necessary or the concentration of the electrolyte is increased. Therefore, when the lead acid battery is formed, the electrolyte solution overflows or the concentration is high.

Next, in order to confirm the superiority of the approximate curve Y = −0.125X + 0.8 of the ratio Y calculated in Example 1, the positive electrode active material density X [g / cm ³ ] is 3 as shown in Table 2. 10 ≦ X ≦ 4.8 and 10 liquid lead-acid batteries for automobiles were manufactured in a similar manner to Example 1 except that the ratio Y was changed (Inventions 1 to 13 and Comparisons). Examples 1-10).
Table 2 shows the filling amount and density of the positive electrode active material, the total amount A of the positive electrode active material and the negative electrode active material, the sulfuric acid amount B, the positive electrode active material and the negative electrode active material of the liquid lead-acid batteries for automobiles produced in various ways. The ratio of the filling amount, the ratio Y = B / A, and the presence or absence of an osmotic short circuit are shown. In addition, the presence or absence of the penetration short-circuit was measured by measuring the voltage in the same manner as in Example 1, and then the presence or absence of the penetration short-circuit was confirmed. confirmed.

FIG. 2 shows the relationship between the positive electrode active material density X [g / cm ³ ] and the ratio Y based on Table 2. As shown in Table 2 and FIG. 2, when the ratio (B / A) of the total amount A of the positive and negative electrode active materials and the amount of sulfuric acid B (B / A) is Y, and the positive electrode active material density is X [g / cm ³ ] In the range where the ratio Y was set to -0.125X + 0.8 ≦ Y, no osmotic short circuit was observed. However, the occurrence of permeation short circuit was confirmed in the range where the ratio Y was set to -0.125X + 0.8 ≧ Y.
Even in this case, when Y exceeds a value of −0.125x + 0.9, no permeation short circuit is observed, but it is necessary to increase the amount of electrolyte or increase the concentration of electrolyte more than necessary. Therefore, when the lead acid battery is formed, the electrolyte overflows or the concentration is high.

Next, typical liquid lead acid batteries that fall within the range of −0.125X + 0.8 ≦ Y ≦ −0.125X + 0.9 (provided that 3.8 ≦ X ≦ 4.6) among the various liquid lead acid batteries produced. (Inventions 2, 6, and 11) and a 5-hour rate discharge test were conducted to confirm the utilization rate of the positive electrode plates of typical liquid lead acid batteries (Comparative Examples 3 and 11) outside the range. The conditions for the 5-hour rate discharge test were set at a constant ambient temperature of 25 ° C., a discharge current of 5.4 A, and a final discharge voltage of 10.5 V. And the utilization factor of the positive electrode active material at that time was calculated.
In this example, the calculation of the utilization rate of the positive electrode plate is the ratio between the discharge capacity when ap (g) and the theoretical capacity of the total amount of active material contained in the positive electrode is bp (g). The active material utilization rate (%) = ap / bp × 100.
Then, the heavy load life test was done using the various liquid lead acid batteries (Invention 2, 6, 11, Comparative Example 3, 11) used in the 5-hour rate discharge test. The conditions of the heavy load life test were as follows: a constant current discharge of 5 A for 1 hour and then a constant current charge of 1.25 A for 5 hours in a water bath at 40 to 45 ° C. This constant current discharge and constant current charge was made into 1 cycle, and the capacity | capacitance test was done every 25 cycles. The capacity test was performed at a constant ambient temperature of 25 ° C., discharged at a discharge current of 20.0 A to a discharge end voltage of 10.5 V, and reached the end of life when it fell below 50% of the initial capacity.
Table 3 shows the utilization rate of various types of liquid lead acid batteries (Inventions 2, 6, 11 and Comparative Examples 3 and 11) and the cycle life results of the heavy load life test.

As shown in Table 3, in various liquid lead-acid batteries (Inventions 2, 6, 11 and Comparative Examples 3, 11), Inventions 2 and 11 are excellent in the utilization rate and cycle life characteristics of the positive electrode plate, In contrast, in the present invention 6 and Comparative Examples 3 and 11, no permeation short circuit was observed, but in Comparative Example 3, the utilization rate was good, but the cycle life number was good, but in Comparative Example 11, the utilization rate was good. Can be seen to be significantly lower. When various liquid lead-acid batteries were disassembled after the heavy load life test, in Comparative Example 3, softening of the active material was promoted because the positive electrode active material density was low.
In the present invention 6, since the specific amount of sulfuric acid was inevitably increased in order to obtain a prescribed amount of sulfuric acid, the lattice corrosion progressed as compared with the liquid lead acid batteries of the present inventions 2 and 11, and the cycle life was reduced. There was no significant improvement.

From the above results, when the ratio (B / A) of the total amount A and the sulfuric acid amount B is Y and the positive electrode active material density is X [g / cm ³ ], −0.125X + 0.8 ≦ Y (provided that By satisfying 3.8 ≦ X ≦ 4.6), it is possible to provide a liquid lead-acid battery that suppresses generation of dendrites due to being left overdischarged, prevents a short circuit, and has improved life characteristics.

The graph which shows the relationship of the ratio (B / A) of the sum total A of the filling amount with respect to positive electrode active material amount X (X = 4.0, 4.4), and the amount B of sulfuric acids. The graph which shows the relationship of the ratio (B / A) of the sum total A of the filling amount with respect to the amount X of positive electrode active materials X (3.6 <= X <= 4.8), and the amount B of sulfuric acids.

Claims (1)

An electrode plate group in which a positive electrode plate and a negative electrode plate formed by filling a lead alloy substrate with an active material paste are alternately stacked via a separator is housed in a battery case, and a large amount of electrolyte is contained in the battery case. In the liquid lead-acid battery in which a large amount of electrolyte is injected so that a free electrolyte exists, the total amount of the positive electrode active material charged in the positive electrode plate and the negative electrode active material amount charged in the negative electrode plate is A, If the amount of sulfuric acid contained in the electrolyte solution is B (completely charged and the initial state is not deteriorated), the ratio of the total amount A to the amount of sulfuric acid B (B / A) is Y, the positive electrode active material density Is a liquid lead-acid battery satisfying a relationship of −0.125X + 0.8 ≦ Y (where 3.8 ≦ X ≦ 4.6), where X is [g / cm ³ ].