JP6071116B2 - Lead acid battery - Google Patents

Description

  The present invention relates to a lead-acid battery, and more particularly to reducing the interval between a positive electrode plate and a negative electrode plate and increasing the discharge capacity.

  In a lead storage battery, positive electrode plates and negative electrode plates are alternately stacked to form an electrode plate group, and a separator is disposed between the positive electrode plate and the negative electrode plate. Then, the electrode plate group is housed in a battery case and immersed in a dilute sulfuric acid electrolyte. The positive electrode plate and the negative electrode plate are made of a lead alloy grid filled with an active material. To increase the capacity of the lead-acid battery, the interval between the positive and negative electrode plates is shortened, and the active material filling amount is increased. It is possible to increase the number of sheets. However, if the distance between the electrode plates is reduced, the positive and negative electrode plates may be short-circuited due to dropping of the positive electrode active material during heavy load discharge or charging after leaving the overdischarge. Therefore, the inventor searched for a condition that does not cause a short circuit even if the interval between the electrode plates is narrowed, and arrived at the present invention.

  The related art is shown below. Patent Document 1 (JPS52-136332A) discloses that the addition of Al ions to the electrolyte of a lead storage battery can suppress the growth (sulfation) of a dense lead sulfate crystal on the negative electrode active material. In Patent Document 2 (JPS62-131480A), the addition of alumina or sodium aluminate is effective in preventing short circuit during charging after being left overdischarged in a retainer type lead-acid battery in which an electrolytic solution is held on a glass fiber mat. It is disclosed. Patent Document 3 (JP2008-243487A) discloses that Al ions and Li ions are added to the electrolyte of a lead storage battery.

JPS52-136332A JPS62-131480A JP2008-243487A

  A basic object of the present invention is to provide a lead-acid battery that does not cause a short circuit even when the interval between electrode plates is reduced, and that is excellent in low-temperature HR discharge performance (low-temperature high-rate discharge performance).

According to the present invention, a plurality of positive electrode plates provided with an active material containing lead dioxide in a lattice made of a lead alloy and negative electrode plates provided with an active material containing metal lead in a lattice made of a lead alloy are alternately arranged. In a lead storage battery in which a group of electrode plates laminated in a battery case is immersed in a dilute sulfuric acid electrolyte, the separator is a bag and the negative electrode is stored, and the electrolyte contains 0.02 mol / L of Li ions. The content is 0.2 mol / L or less, and the average distance between the positive electrode plate and the negative electrode plate in the electrode plate group is 0.5 mm or more and 0.8 mm or less. Note that the invention relating to Japanese Patent Application No. 2014-185165, which is the original application of the present application, and the invention of Patent 5618253 corresponding to the original application both have an Al ion concentration of 0.02 mol / L or more .

The main findings obtained by the inventor regarding this invention are as follows.
1) Short circuit due to heavy load discharge can be eliminated by storing the negative electrode plate instead of the positive electrode plate in the separator (Tables 1 and 2).
2) The short circuit caused by charging after being left overdischarged cannot be resolved even if the negative electrode plate is housed in the separator, but can be resolved by adding 0.02 to 0.2 mol / L Al ion or Li ion to the electrolyte. The addition of Al ions is also effective in suppressing sulfation.
3) Low temperature HR performance decreases with Al ion addition. The addition of Li ions can prevent the low-temperature HR performance from being degraded.
4) The effect of Al ion and Li ion is 0.02mol / L, which is sufficiently large. Even if added over 0.2mol / L, the effect is not increased. Therefore, Li ions are added in an amount of 0.02 mol / L to 0.2 mol / L.
5) There is a region where the effect of Al ions and Li ions appears more remarkably when the electrode plate interval is narrowed. The region where the electrode plate interval is 0.5 to 0.8 mm and the Al ion and Li ion content is 0.02 to 0.2 mol / L is this region, and the low temperature HR performance is improved as compared with the case where the electrode plate interval is as wide as 1 mm.

In this specification, the concentration of Al ions and Li ions is expressed as the concentration of Al ions and Li ions per mol of electrolyte (mol / L). One mole of Al ions corresponds to 171.05 g of aluminum sulfate (Al ₂ (SO ₄ ) ₃ ). The indication of 0.02 to 0.2 mol / L means 0.02 mol / L or more and 0.2 mol / L or less, and A to B means A or more and B or less. The interval between the electrode plates is preferably constant, and when there is a distribution in the interval, an average value is used.

Cross-sectional view of the electrode plate lower part of the lead storage battery of the example Characteristic diagram showing the relationship between electrode plate spacing and low-temperature HR discharge characteristics when equal concentrations of Li and Al ions are added

  Hereinafter, an optimum embodiment of the present invention will be described. In carrying out the present invention, the embodiments can be appropriately changed in accordance with common sense of those skilled in the art and disclosure of prior art.

Manufacture of lead-acid batteries
A 55B24 type lead acid battery (nominal voltage 12V, 5 hour rate rated capacity 36Ah) compliant with JIS D 5301 was manufactured. The positive electrode lattice is an alloy containing 0.07 mass% Ca, 1.5 mass% Sn and inevitable impurities, and the balance is Pb, and the negative electrode lattice is 0.09 mass% Ca, 0.35 mass% Sn and inevitable impurities, and the remainder is Pb. Alloy. Each grid is an expanded grid, but may be a cast grid, and the size is 115 mm in height, 100 mm in width, 1.3 mm in thickness for the positive grid, and 1 mm in thickness for the negative grid.

  The positive electrode active material paste was obtained by adding 0.1 mass% acrylic fiber with 100 mass% of the lead powder produced by the ball mill method, and mixing 13 mass% water and 6 mass% dilute sulfuric acid with a specific gravity of 1.40 (20 ° C.). Negative electrode active material paste is 100 mass% lead powder produced by the ball mill method, 0.2 mass% lignin, 0.3 mass% carbon black, 0.6 mass% barium sulfate, 0.1 mass% acrylic fiber, 11 mass% water and 1.40 specific gravity It was obtained by mixing 7 mass% dilute sulfuric acid (20 ° C.). The lead powder is not limited to the ball mill method, but may be a Barton method. The binder is not limited to acrylic fiber and is optional, and the binder may not be added. The composition of the active material paste for the positive electrode and the negative electrode is arbitrary.

  Filled with 55 g of active material paste per positive grid and 52 g per negative grid and aged for 48 hours at 50 ° C. and 50% relative humidity respectively, then dried in a dry atmosphere at 50 ° C. for 24 hours. A negative electrode plate was obtained. As a separator, a microporous polyethylene sheet was folded in half, and both ends were mechanically sealed to form a bag. The base thickness of the sheet is 0.20 mm, and the separator is a polyethylene sheet in the examples, but is not limited thereto. The material is not particularly limited as long as the negative electrode plate can be packaged.

  As an example, an unformed negative electrode plate accommodated in a separator was prepared, and as an comparative example, an unformed positive electrode plate accommodated in a separator was prepared. For example, eight unformed negative electrode plates and seven unformed positive electrode plates housed in a separator were alternately laminated, and the electrodes of the same polarity electrode plates were welded together to form an electrode plate group. Here, the distance (average value) between the positive electrode plate and the negative electrode plate was changed to 1 mm, 0.8 mm, 0.65 mm, 0.5 mm, 0.4 mm, etc. by changing the height of the separator rib. In the embodiment, there are 8 negative plates and 7 positive plates per electrode plate group. However, when the interval between the electrode plates is reduced, 9 negative plates and 8 positive plates, or both negative and positive plates are used. For example, the number of electrode plates can be increased to 8 for the negative electrode plate and 7 for the positive electrode plate to increase the amount of active material per electrode plate.

Six obtained electrode plate groups are housed in a battery case made of polypropylene and connected in series, and an electrolyte prepared by adding a predetermined amount of Al sulfate and Li sulfate to dilute sulfuric acid with a specific gravity of 20 ° C and 1.230 is injected. Then, a battery case was formed in a 25 ° C. water tank to obtain a 55B24 type lead acid battery. The Al ion source and the Li ion source are optional, and may be added in the form of, for example, aluminum sulfate, lithium sulfate, lithium carbonate, lithium aluminate AlLiO ₂ , aluminum hydroxide and lithium hydroxide. When the electrode spacing is reduced and the amount of active material is increased, the amount of electrolyte per active material decreases, so the concentration of dilute sulfuric acid used in the production of the electrolyte is increased, and the weight of active material and sulfate ions are increased. It is preferable to keep the ratio to the amount substantially constant. Furthermore, the preferred range of the Al ion concentration and the Li ion concentration does not depend on the sulfuric acid concentration in the electrolyte.

  FIG. 1 shows an electrode plate group 2 in the lead storage battery of the embodiment, 4 is a positive electrode plate, 6 is a negative electrode plate and is accommodated in a bag of a separator 8, 10 is a positive electrode grid, 12 is a negative electrode grid, and 10 , 12 are filled with a positive electrode active material 14 and a negative electrode active material 16. The electrode plate interval g and the electrode plate thickness T are determined as shown in FIG. 1. The electrode plate interval g includes the thickness of the separator 8 and protrudes when the active material protrudes outward from the surface of the lattice. The thickness of the active material is included in the thickness T of the electrode plate.

Test method and results For each lead-acid battery (3 samples each)
1) Presence or absence of short circuit after heavy load life test (JIS D 5301: 2006 9.5.5b);
2) Presence or absence of short circuit when charging after leaving overdischarge;
3) Low temperature HR discharge performance (JIS D 5301: 2006 9.5.3b));
4) SBA-IS test (Battery Industry Association Standard SBA S 0101: 2006 9.4.5) The amount of lead sulfate accumulated in the negative electrode active material after 18,000 cycles was examined.
In the heavy load life test standard, charge / discharge is repeated in a predetermined pattern, and the number of cycles until the capacity drops to 50% of the 5-hour rate capacity is obtained. In the examples, not the number of cycles but the number of batteries in which a short circuit occurred after the test (life reached) was evaluated. The reason for examining the number of short-circuited batteries is to evaluate whether the short-circuiting easily occurs and the life is shortened by reducing the distance between the electrode plates. Note that when both Al ions and Li ions were contained in an amount of 0.02 to 0.2 mol / L, short-circuiting did not easily occur even when the electrode plate interval was shortened, and thus the lifetime was not shortened.

In the overdischarge standing test, the battery is discharged for 2.5 hours at a 5-hour rate current from the fully charged state, and the SOC (charged state) is 50%. Connect a 12V-10W lamp at 40 ℃ as a load and leave it for 30 days. Next, after charging for 20 hours at 25 ° C. with a 10 hour rate current, the battery is disassembled and inspected for the presence or absence of a short circuit.
In the low-temperature HR discharge test, discharge at a predetermined current value at -15 ° C and measure the time until the terminal voltage drops to 6V.
In the SBA-IS study,
・ Repeat a cycle consisting of 59 seconds of discharge at 45A, 1 second of discharge at 300A, and 60 seconds of charge at 14V.
・ Leave for 48 hours every 3600 cycles
• Measure the number of cycles until the voltage at the end of discharge drops below 7.2V. In the example, the battery was disassembled at 18,000 cycles, and the amount of lead sulfate accumulated in the negative electrode active material was measured. In general, the smaller the amount of lead sulfate accumulated, the greater the number of cycles until the end of life in the SBA-IS test.

  Table 1 shows the results when the positive electrode plate was accommodated in the separator. Regardless of the Al ion concentration or Li ion concentration, when the positive electrode plate was housed in the separator, a short circuit in the heavy load life test could not be prevented. However, when Al ions were added, a short circuit due to charging after being left overdischarged could be prevented. Table 2 and FIG. 2 show the results when the negative electrode plate was accommodated in the separator. In Tables 1 and 2, the low temperature HR performance is shown as a relative value with Comparative Examples A1 (in the case of Table 1) and A7 (in the case of Table 2). From a practical standpoint, the low temperature HR performance is preferably 100 or more, and the amount of lead sulfate accumulated in the SBA-IS test is preferably 80 or less.

  When the negative electrode plate was stored in the separator, no short circuit occurred in the heavy load life test. This is presumably because the active material dropped from the positive electrode plate in the heavy load life test was collected at the bottom of the battery case and did not cause a short circuit. Short-circuiting due to charging after being left overdischarged did not occur in the presence of Al ions at a concentration of 0.02 mol / L or more, and lead sulfate accumulation in the SBA-IS test could be suppressed by addition of Al ions. When Al ions are added, the low-temperature HR performance decreases, but when used together with Li ions, there is a region where the low-temperature HR performance improves compared to the case where neither AL ions nor Li ions are added. In this region, Al ions are 0.02 to 0.2 mol / L and Li ions are 0.02 to 0.2 mol / L. Even if the Al ion concentration was 0.3 mol / L (sample A16) or the Li ion concentration was 0.3 mol / L (sample A15), no further improvement in performance was obtained, so the upper limit of the concentration was 0.2 mol / L. L.

  FIG. 2 shows the low temperature HR performance when the concentrations of Al ions and Li ions are changed to 0.02 mol / L, 0.1 mol / L, and 0.2 mol / L. The low-temperature HR performance increases only by reducing the electrode plate interval from 1 mm to 0.8 to 0.5 mm, but the low-temperature HR performance is further improved when both the Al ion and Li ion concentrations are in the range of 0.02 to 0.2 mol / L. In addition, the effect is remarkable when the distance between the electrode plates is 0.8 to 0.5 mm rather than 1 mm. Therefore, unexpected effects other than reducing the electrode plate interval and increasing the amount of active material can be obtained. The inventor made a battery with the electrode plate interval of 0.4 mm, but even when Al ions were 0.2 mol / L, short-circuiting due to charging after being left overdischarged occurred frequently.

The presence or absence of Al ions is optional.

2 Electrode plate group 4 Positive electrode plate 6 Negative electrode plate 8 Separator 10 Positive electrode lattice 12 Negative electrode lattice 14 Positive electrode active material 16 Negative electrode active material

g Electrode spacing d Grid thickness T Electrode thickness

Claims (1)

An electrode in which a positive electrode plate having an active material containing lead dioxide on a grid made of a lead alloy and a negative electrode plate having an active material containing lead metal on a grid made of a lead alloy are alternately stacked via a separator. In a lead storage battery in which a group of plates is stored in a battery case and immersed in a dilute sulfuric acid electrolyte,
The separator has a bag shape and stores a negative electrode plate,
The electrolyte contains 0.02 mol / L to 0.2 mol / L of Li ions,
The lead acid battery, wherein an average distance between the positive electrode plate and the negative electrode plate in the electrode plate group is 0.5 mm or more and 0.8 mm or less.

Images