JP2007184124A - Method of manufacturing valve regulated lead acid battery, and valve regulated lead acid battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method capable of effectively suppressing dendrite short occurrence without impairing an output characteristic of a battery; and to provide a valve regulated lead acid battery. <P>SOLUTION: This method of manufacturing the valve regulated lead acid battery provided with an electrode plate group with a mat separator impregnated with and retaining an electrolyte arranged between a positive electrode plate and a negative electrode plate is characterized by including: a first charging step for injecting the electrolyte containing sulfuric acid into every unit cell with the electrode plate group composed of chemically non-converted electrode plates housed therein and charging the battery by a first charging current I<SB>1</SB>after the electrolyte injection; a storage step for leaving the battery on a shelf for a predetermined period after the first charging step; and a second charging step executed after the storage step for charging the battery by a second charging current I<SB>2</SB>smaller than the first charging current I<SB>1</SB>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a control valve type lead storage battery and a control valve type lead storage battery.

  In particular, a control valve type lead storage battery for an electric vehicle is required to have a high output as well as a large capacity. In order to increase the output, the electrode plates are made thinner or the distance between the electrode plates is set shorter. Also, the amount of active material per electrode plate group volume constituting the unit cell tends to be set larger for the purpose of increasing the capacity.

  On the other hand, as a chemical charging method for a control valve type lead-acid battery, a so-called battery formation method is widely adopted in which a battery is assembled with an unformed electrode plate, and an electrolytic solution containing sulfuric acid is injected to conduct energization. As another conversion method, positive and negative unformed electrode plates are placed in a conversion tank, and the electrode plates are pre-formed before battery assembly. It has been adopted.

  In the case of electrode plate formation, the active material strength is fragile especially in the positive electrode plate thinned for high output, so the active material may fall off during the battery assembly process, It becomes a factor. Therefore, in such a battery, it is common to assemble the battery with an unformed electrode plate having a higher strength than that of the formed electrode plate, and to perform battery case formation.

  In addition, the battery tank formation method does not require cleaning and drying processes for the chemical conversion tank and the formed electrode plate that are necessary for the electrode plate formation method, so the manufacturing process can be simplified and the equipment cost is also better than the electrode plate formation method. Is also excellent.

  However, when a battery with a larger amount of active material per electrode plate group volume or with a shorter distance between the electrode plates is formed into a battery case, the inside of the battery is formed at the initial stage of battery formation after the electrolyte is injected. Thus, the problem of internal short circuit between the positive electrode and the negative electrode has become apparent.

  The active material of the unformed positive electrode and the negative electrode contains lead oxide or basic lead sulfate as a main component, and exhibits basicity as a whole of the unformed active material. Therefore, the sulfuric acid contained in the electrolytic solution injected into the cell is neutralized with the unformed active material, and the sulfuric acid in the electrolytic solution is consumed.

  In particular, in a battery having a large amount of active material per electrode plate group volume, the neutralization reaction described above proceeds rapidly, and the sulfuric acid concentration in the electrolytic solution decreases rapidly, so that the pH of the electrolytic solution increases rapidly. As the pH of the electrolyte increases, the solubility of Pb ions in the electrolyte increases.

  Thus, the Pb ions eluted in the electrolytic solution are precipitated as dendritic crystals (dendrites) on the negative electrode plate in the early stage of battery case formation. In particular, in a battery having a short distance between electrode plates, the dendrite easily penetrates the separator, causing a short circuit between the positive electrode and the negative electrode.

  In order to suppress such a short circuit between the positive electrode and the negative electrode due to dendrites, for example, Patent Document 1 shows a configuration in which acid-resistant inorganic powders such as silica and alumina are added to a glass fiber mat used for a separator. Has been.

  By such inorganic powder, the hole in a separator becomes a maze shape, the linear growth of a dendrite in a separator is suppressed, and a short circuit is suppressed.

In Patent Document 2, borate is fixed to the glass fiber used for the separator, and the increase in the Pb ion solubility when the electrolyte pH immediately after injection is increased is suppressed, and the amount of precipitation of the dendrite itself is suppressed. Has been shown to do.
JP 11-260335 A JP 2003-338271 A

  According to the configurations of Patent Document 1 and Patent Document 2 as described above, it is possible to suppress a dendrite short to some extent. However, in the configuration of Patent Document 1, for example, since the inorganic powder is disposed in the separator, the internal resistance between the electrode plates is increased, and the voltage at the time of sudden discharge is decreased, so that the output is decreased.

  Moreover, in the structure of patent document 2, since the ion which does not contribute to the charging / discharging reaction of a battery is added in electrolyte solution, the spreading | diffusion of the sulfate ion at the time of charging / discharging is inhibited, There was a problem that output characteristics deteriorated due to an increase in internal resistance.

  The present invention provides a control valve type lead-acid battery manufacturing method that suppresses dendrite short-circuiting after injection while maintaining output characteristics at a high level.

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention provides a control valve type lead-acid battery including an electrode plate group in which a mat separator for impregnating and holding an electrolyte is interposed between a positive electrode plate and a negative electrode plate. In this method, an electrolytic solution containing sulfuric acid is injected into each unit cell in which the electrode plate group composed of unformed electrode plates is accommodated, and the battery is charged with the first charging current (I ₁ ) after the electrolytic solution is injected. A first charging step for charging; a leaving step for leaving the battery for a predetermined time after the first charging step; a first step that is performed following the leaving step and is less than the first charging current (I ₁ ). The manufacturing method of a control valve type lead acid battery including the 2nd charge step charged with ₂ charging currents (I2) is shown.

The invention according to claim 2 of the present invention is characterized in that, in the control valve type lead-acid battery manufacturing method of claim 1, the first current (I ₁ ) is 0.3 CA or more.

  Furthermore, the invention according to claim 3 of the present invention is the method of manufacturing a control valve type lead storage battery according to claim 1 or 2, wherein the sulfuric acid mass (X) contained in the dilute sulfuric acid electrolyte injected into the unit cell, X / (P + N) is 0.15 or less in the amount of positive electrode unformed active material (P) and the amount of negative electrode unformed active material (N) included in the unit cell.

According to a fourth aspect of the present invention, in the method for manufacturing a control valve type lead-acid battery according to the first, second, or third aspect, after the second charging step, at least the second charging current (I ₂ ). It includes a third charging step of charging with a _third charging current (I ₃ ) which is large.

  And the invention which concerns on Claim 5 of this invention shows the control valve type lead acid battery obtained by the manufacturing method of the control valve type lead acid battery of Claim 1, 2, 3 or 4. FIG.

  According to the configuration of the present invention described above, for the purpose of increasing the capacity and output of the battery, the amount of active material per electrode plate group volume is set more or even in a battery with a shorter distance between the electrode plates, It is possible to remarkably suppress the occurrence of a dendrite short between the positive electrode and the negative electrode that occurred in the early stage of battery case formation.

  The manufacturing method of the control valve type lead acid battery (henceforth battery) by embodiment of this invention is demonstrated.

  FIG. 1 shows an unformed battery 101 to which the present invention is applied. The battery 101 has a structure in which an electrode plate group 104 is accommodated in a cell chamber 103 provided in a battery case 102. In the electrode plate group 104, a mat separator 107 such as a glass fiber mat capable of impregnating and holding an electrolyte is disposed between the positive electrode plate 105 and the negative electrode plate 106.

  The positive electrode plate 105 and the negative electrode plate 106 have the same polarity connected by a shelf 108, and a connection member 109 for leading the battery output to the outside or connecting between adjacent electrode plate groups 104 to the shelf 108. Is provided. The battery case 102 is joined with a lid 111 provided with a liquid injection port 110.

  Further, in the battery 101 before the application of the present invention, the positive electrode plate 105 and the negative electrode plate 106 are filled with an active material in an unformed state, respectively.

  FIG. 2 is a step diagram showing the method for manufacturing the control valve type lead storage battery of the present invention.

  An electrolyte containing dilute sulfuric acid is injected into the cell chamber 103 of the battery 101 assembled with the positive electrode plate 105 and the negative electrode plate 106 in the unformed state.

Next, the battery 101 is energized and formed by the first current application (I ₁ ). This is the first charging step. The first charging current (I ₁ ) is larger than the second charging current (I ₂ ) that is the charging current value in the second charging step described later, but is 0.30 CA for the battery 101. It is preferable to carry out at the above current value. However, the excessive charging current is preferably set to 0.75 CA or less because excessive heat generation and liquid reduction from the battery 101 are large and chemical conversion efficiency is lowered. The charging time in the first charging step may be set to about 10 seconds to 600 seconds.

  After the first charging step is completed, the battery 101 is left without being charged / discharged. The battery leaving time in the leaving step can be set to about 60 seconds to 30 minutes.

After the leaving step is completed, a second charging step is performed in which the battery 101 is charged with a _second charging current (I ₂ ) lower than the first charging current (I ₁ ) in the first charging step. This second charging step can be continued until the formation of the battery 101 is completed. Therefore, the charging time in the second charging step is determined based on the discharge capacity of the battery 101, the amount of electricity charged in the first charging step, and the second charging current (I ₂ ) value. It may be set so that a sufficient amount of electricity necessary for the operation can be secured.

  Needless to say, if a cap valve (not shown) or the like is attached to the liquid injection port 110 and the control valve structure is arranged after the formation of the battery case, a control valve type lead storage battery according to the manufacturing method of the present invention can be obtained.

  In order to suppress the dendrite growth in the early stage of battery case formation, the inventors of the present invention temporarily stopped energization in the early stage of formation, and after an appropriate pause time, the current value was lower than the initial formation current value. It has been found that forming a battery case has a very remarkable effect.

  Such a mechanism of the effect of the present invention is not clear. In the first charging step, the positive and negative active materials are charged and changed to lead dioxide and lead, respectively. At the beginning of energization, Pb ions dissolved in the electrolyte solution are reduced on the negative electrode plate, and it is considered that dendrites begin to grow. Short circuit between electrode plates.

  However, since the dendrite growth is suppressed by temporarily stopping energization, the crystal growth point of the dendrite is deactivated for some reason, or the dendrite crystal nucleus disappears, etc. Presumed to be inactivated.

Note that if the first charging step takes a long time, a dendrite short circuit may occur during the first charging step. In addition, since the time to a dendrite short may vary depending on the battery design, check it in advance and set it to an appropriate time. However, in a normal control valve type lead-acid battery, the charging current (I ₁ ) is the battery capacity. On the other hand, in the range of 0.05 to 1.0 CA, the charging time of the first charging step can be set in the range of about 10 seconds to 600 seconds.

  However, this value is considered to depend on the battery design factors such as the mass and concentration of sulfuric acid in the electrolytic solution, the ratio of positive / negative active material per cell, or the thickness of the separator. It is desirable to set the charging time in advance within a range where a dendrite short circuit does not occur during the first charging step.

Further, it is particularly preferable that the first charging current (I ₁ ) is 0.3 CA or more because not only dendrite shorts but also visible dendrite growth can be suppressed to almost zero.

  If the standing time in the standing step is at least 40 seconds or more, preferably 60 seconds or more, a dendrite short-circuit suppressing effect can be obtained. In addition, it is preferable to perform a confirmation experiment for each battery model and set the lower limit for this time. In order to obtain the effect of the present invention, there is no upper limit of the standing time, but increasing the standing time increases the time required for the formation of the battery case and leads to lead sulfate conversion during the standing time. Since it progresses and chemical conversion efficiency falls, it is not preferable to make it longer than necessary. Normally, this time may be set within 4 hours.

Following standing step, although the first charge current (I ₁₎ is lower than the second charge current (I ₂₎ performing second charging step, the second charging current (I ₂₎ first charging If the current (I ₁ ) or more is confirmed, it has been confirmed that the dendrite growth recurs. Therefore, the second charging current (I ₂ ) is set lower than the first charging current (I ₁ ).

Although the second charging step may be continued until the formation is completed, the formation of dendrites is suppressed when the formation progresses to a certain extent, the pH of the electrolytic solution decreases, and the electrolytic solution becomes a strongly acidic region. Therefore, when this region is reached, the second charging step is completed, and after that, charging is performed with a _third charging current (I ₃ ) exceeding the _second charging current (I ₂ ), and battery case formation is performed. Completion in a relatively short time is also extremely effective from the viewpoint of productivity.

  In particular, the configuration of the present invention is extremely effective for a battery having a configuration in which a dendrite short-circuit is likely to occur by including many active materials in a unit cell. In a battery having such a configuration, it is conceivable to use a relatively high concentration of dilute sulfuric acid as an electrolytic solution. However, the conversion efficiency is drastically decreased and the conversion is increased, that is, conversion from an unconverted active material to a converted active material. In most cases, high-concentration dilute sulfuric acid cannot be applied because the rate decreases and the initial capacity of the battery rapidly decreases.

  As a result of confirmation by the present inventors, the mass of sulfuric acid (X) contained in the electrolyte solution injected into the unit cell, the amount of positive electrode unformed active material (P) contained in the unit cell, and the amount of negative electrode unformed active material In (N), a battery in which X / (P + N) is 0.15 or less has a very high probability of a dendrite short circuit occurring during battery case formation.

  As a result of considering the high output of such a battery, even in a control valve type lead-acid battery designed to have frequent dendritic shorts, the production method of the present invention significantly reduces the occurrence of dendritic shorts during battery case formation. Since it can suppress, it turns out that the manufacturing method of this invention is especially preferable for such a battery whose ratio (X / (P + N)) was 0.15 or less.

  Hereinafter, the effects of the present invention will be described with reference to examples.

  First, a 12V60 Ah control valve type lead storage battery was assembled with unformed electrode plates for both positive and negative electrodes. The unit cell constituting this battery includes 11 positive electrode plates and 12 negative electrode plates, and a glass mat separator having a thickness of 1.0 mm when a group pressure of 19.6 kPa is applied is provided between the positive electrode plate and the negative electrode plate. It is arranged.

  This unformed battery was formed into a battery case using the energization pattern shown in Table 1. The total amount of unformed active material of the positive electrode and the negative electrode constituting the single cell is constant, and the amount of unformed active material of the positive electrode is changed to P, and the amount of unformed active material of the negative electrode is changed by changing the sulfuric acid concentration in the electrolytic solution. The ratio (X / (P + N)) when the amount N and the sulfuric acid mass X in the electrolyte solution were used was changed.

A description will be added to Table 1. Case Al to A4, the B1~B4 and C1~C4 are first performed for 60 seconds charging step as 0.2~0.7CA showing a charging current I ₁ in Table 1, respectively, subsequent to the charging step, left Is performed for 600 seconds, and then the second charging step is performed for 36 hours at a charging current I ₂ of 0.2 CA.

Case D1 to D4, the E1~E4 and F1~F4 performs 60 seconds first charging step as 0.2~0.7CA showing a charging current I ₁ in Table 1, respectively, without standing, first This is a case where the second charging step is performed for 36 hours at a charging current I ₂ of 0.2 CA continuously to the charging step.

For cases A5, A6, B5, B6, C5 and C6, the charging current I ₁ is 0.2 CA or 0.1 CA shown in Table 1, respectively, and the first charging step is performed for 36 hours or 72 hours shown in Table 1, respectively. This is the end of chemical conversion.

  A battery case was formed in each case shown in Table 1 above. A single cell was taken out from each battery after battery case formation, the presence or absence of a dendrite short was confirmed, and the occurrence rate (%) of the dendrite short was investigated for each single cell. The results are shown in Table 2.

From the results shown in Table 2, a leaving period is provided between the first charging step (charging current I ₁ ) and the second charging step (charging current I ₂ ), and the relationship between the charging currents is expressed as I ₁ > I. _It can be seen that according to the production method of the present invention, the occurrence rate of dendrite shorts during the formation of the battery case can be significantly reduced. Moreover, although dendrite can be confirmed as an off-white precipitate in the mat separator, in the present invention, no off-white trace indicating dendrite growth was observed in the mat separator.

On the other hand, when the charge current relationship is I ₁ ≦ I ₂ , the occurrence of a dendrite short was observed. In addition, dendrite short-circuiting was also observed when charging was continued without providing a standing period.

  In addition, regarding the ratio of the amount of sulfuric acid to the amount of the unformed active material, in particular, when the ratio is 0.13 and 0.15, the incidence of dendrite shorts is higher than in the case of 0.18. From the viewpoint of chemical conversion efficiency, the ratio may be set as low as possible. However, in the comparative example, setting such a ratio low is not preferable because the incidence of dendrite short increases.

  In the present invention, even when the ratio is set to 0.15, the occurrence of dendrite shorts can be suppressed remarkably. Therefore, the conventional conflicting problems of improvement in chemical conversion efficiency and dendrite shorts are solved. Can be compatible.

  In addition, if the leaving time set between the first charging step and the second charging step is within an appropriate range, the effect of the present invention hardly changes even if it fluctuates within that range, and has a large influence. It was confirmed by the experiment conducted separately that it was not received.

  Further, the distance between the electrode plates, that is, the thickness of the mat separator, is a factor that greatly affects the dendrite short-circuit occurrence rate. The thickness of the battery mat separator shown in Table 1 is changed from 1.0 mm to 1.3 mm to 1.3 mm. The dendrite short-circuit occurrence rate was compared for those having a thickness changed from 1.0 mm to 0.8 mm, and the dendrite short-circuit occurrence rate increased with decreasing mat separator thickness under all conditions.

  In particular, the mat separator thickness is less than 1.2 mm, and the probability of dendrite shorts suddenly increases in the areas where the thickness is 1.0 mm and 0.8 mm. It is particularly suitable for a new battery.

  Further, in the present invention, other substances that do not contribute to the charge / discharge reaction of the battery, such as inorganic powders and borates for inhibiting the growth of dendrites, as shown in Patent Document 1 and Patent Document 2, are used. The dendrite short-circuit can be suppressed without adding any of these substances, so the disadvantages of adding these substances into the battery, that is, the decrease in discharge voltage characteristics due to the increase in internal resistance and the decrease in ion diffusion rate, can be avoided, and the output characteristics Is maintained at a high level, and a control valve type lead-acid battery in which dendrite short-circuit does not occur can be stably obtained.

  The present invention remarkably suppresses dendrite shorts that occur when a control valve type lead-acid battery is formed into a battery case, and is therefore extremely suitable as a method for manufacturing a control valve-type lead acid battery.

The figure which shows the cross section of the battery of the unformed state which applies this invention The step figure which shows the manufacturing method of the control valve type lead acid battery of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Battery 102 Battery case 103 Cell chamber 104 Electrode plate group 105 Positive electrode plate 106 Negative electrode plate 107 Mat separator 108 Shelf 109 Connecting member 110 Injection port 111 Lid

Claims (5)

A control valve type lead-acid battery manufacturing method comprising an electrode plate group in which a mat separator that impregnates and holds an electrolyte solution is disposed between a positive electrode plate and a negative electrode plate, and a unit that accommodates the electrode plate group composed of unformed electrode plates A first charging step in which an electrolytic solution containing sulfuric acid is injected into each cell, the battery is charged with a _first charging current (I ₁ ) after the electrolytic solution is injected, and the battery is charged for a predetermined time after the first charging step. A control step including a leaving step of leaving and a second charging step that is performed subsequent to the leaving step and is charged with a second charging current (I ₂ ) that is less than the first charging current (I ₁ ). Manufacturing method of valve-type lead acid battery. The method for manufacturing a control valve type lead-acid battery according to claim 1, wherein the first charging current (I ₁ ) is 0.3 CA or more. In the mass of sulfuric acid (X) contained in the electrolyte solution injected into the unit cell, the amount of positive electrode unformed active material (P) and the amount of negative electrode unformed active material (N) contained in the unit cell, X / ( P + N) is 0.15 or less, The manufacturing method of the control valve type lead acid battery of Claim 1 or 2 characterized by the above-mentioned. After the second charging step, a third charging step of charging in the third charging current is larger than at least the second charge current _{(I 2) (I 3)} , according to claim 1, 2 or 3. A method for producing a control valve type lead storage battery according to 3. The control valve type lead acid battery obtained by the manufacturing method of the control valve type lead acid battery of Claims 1-4.

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