JP7060858B2 - Judgment method of liquid reduction performance of lead-acid battery, and lead-acid battery and its charging method - Google Patents

Description

The present disclosure relates to a method for determining the liquid reducing performance of a lead storage battery, and a lead storage battery and a charging method thereof.

In recent years, various fuel efficiency improvement measures have been studied for automobiles in order to prevent air pollution or global warming. Vehicles with fuel efficiency improvement measures include, for example, an idling stop system vehicle (hereinafter referred to as "ISS vehicle"; start-stop system vehicle) that reduces the operating time of the engine, and power generation that reduces the power generation of the alternator by the power of the engine. Micro-hybrid vehicles such as control vehicles are being considered.

In lead-acid batteries, large current charging may be repeated due to regenerative charging or the like. When relatively deep charging / discharging is repeated, if the high rate discharging performance of the lead storage battery is insufficient, for example, when the engine is restarted after idling stop, the battery voltage drops and restarting cannot be performed. In particular, in recent years, it has become an important issue to improve low-temperature and high-rate discharge performance so that it can be used even in low-temperature areas such as those used below freezing point.

On the other hand, Patent Document 1 below discloses a technique for improving low-temperature and high-rate discharge performance by using a lignin sulfonate having a conjugated double bond as the lignin sulfonate contained in the negative electrode active material. ing.

Japanese Unexamined Patent Publication No. 9-147771

By the way, it is known that when high current charging is repeated in a lead storage battery, electrolysis of water in the electrolytic solution occurs. When electrolysis occurs, oxygen gas and hydrogen gas generated by the decomposition of water are discharged to the outside of the battery, so that the amount of water in the electrolytic solution is reduced. As a result, the concentration of sulfuric acid in the electrolytic solution increases, and the capacity decreases due to corrosion deterioration of the electrodes (positive electrode and the like). For this reason, when the amount of water in the electrolytic solution of the lead-acid battery decreases, it is necessary to replenish the reduced amount of water for maintenance. However, for lead-acid batteries, the electrolytic solution is maintained from the viewpoint of maintenance-free. It is required to suppress the decrease (reduction of liquid) of the water inside. As a method for evaluating the liquid-reducing performance, a constant voltage charge test in an overcharged state may be used. However, there may be no correlation between the liquid reduction performance in the overcharged state and the liquid reduction performance in the partially charged state during actual use.

The present disclosure has been made in view of the above circumstances, and an object of the present invention is to provide a method for determining the liquid-reducing performance of a lead-acid battery, which can predict the liquid-reducing performance in a partially charged state. Further, the present disclosure describes a lead-acid battery and a charging method thereof that can suppress the deviation of the reduced amount of the electrolytic solution in the partially charged state from the reduced amount of the electrolytic solution in the overcharged state in comparison with the same voltage. The purpose is to provide.

One aspect of the present disclosure is the unipolar potential of the positive electrode obtained when a partially charged lead-acid battery is charged at a constant voltage, and the unipolar potential of the positive electrode in an overcharged state at the same voltage as the constant voltage charging voltage. Provided is a method for determining the liquid-reducing performance of a lead-acid battery, which determines the liquid-reducing performance of the lead-acid battery based on the average value of the absolute values of the differences from the above.

Conventionally, it was difficult to predict the liquid reduction performance in the partially charged state during actual use by the constant voltage charge test in the overcharged state, but according to the above-mentioned method for determining the liquid reduction performance of the lead storage battery, the liquid reduction performance is predicted. be able to.

Another aspect of the present disclosure is a single pole potential of the positive electrode obtained when a partially charged lead-acid battery is charged at a constant voltage, and a single electrode of the positive electrode in an overcharged state at the same voltage as the constant voltage charging voltage. Provided is a lead acid battery in which the average value of the absolute value of the difference from the polar potential is less than 0.07V.

Another aspect of the present disclosure is a method for charging a lead storage battery in which a partially charged lead storage battery is charged at a constant voltage, wherein the unipolar potential of the positive electrode obtained when the lead storage battery is charged at the constant voltage and the constant voltage charging are performed. Provided is a method for charging a lead storage battery, wherein the average value of the absolute value of the difference between the voltage and the unipolar potential of the positive electrode in the overcharged state at the same voltage is less than 0.07 V.

Conventionally, it was difficult to predict the liquid reduction performance in the partially charged state during actual use by the constant voltage charging test in the overcharged state, but according to the above-mentioned lead-acid battery and its charging method, the overcharged state is compared with the same voltage. It is possible to suppress the deviation of the reduced amount of the electrolytic solution in the partially charged state from the reduced amount of the electrolytic solution in the above.

According to the present disclosure, it is possible to provide a method for determining the liquid-reducing performance of a lead-acid battery, which can predict the liquid-reducing performance in a partially charged state. Further, according to the present disclosure, a lead-acid battery capable of suppressing the deviation of the reduced amount of the electrolytic solution in the partially charged state from the reduced amount of the electrolytic solution in the overcharged state and its charging in comparison with the same voltage. A method can be provided. According to the present disclosure, it is possible to provide an electric vehicle equipped with such a lead storage battery. According to the present disclosure, it is possible to provide a micro-hybrid vehicle (for example, an ISS vehicle and a power generation control vehicle) equipped with the above-mentioned lead storage battery. According to the present disclosure, it is possible to provide an application of a lead storage battery to an electric vehicle. According to the present disclosure, the application of lead-acid batteries to micro-hybrid vehicles can be provided. According to the present disclosure, it is possible to provide an application of a lead storage battery to an ISS vehicle. According to the present disclosure, it is possible to provide an application of a lead storage battery to a power generation control vehicle.

It is a perspective view which shows the whole structure and the internal structure of the lead storage battery which concerns on one Embodiment. It is a perspective view which shows the electrode group of the lead storage battery which concerns on one Embodiment. It is a figure which shows the bag-shaped separator and the electrode accommodated in the bag-shaped separator. It is a figure which shows an example of a separator. It is sectional drawing which shows an example of the arrangement of a separator and an electrode plate. It is a figure which shows an example of the current-voltage curve when the overvoltage is applied to the lead storage battery in the overcharged state. It is a figure which shows an example of a unipolar potential and a gas generation rate when a lead storage battery in a partially charged state is charged by a constant voltage.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as appropriate.

In the present specification, the numerical range indicated by using "-" indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively. Within the numerical range described stepwise herein, the upper or lower limit of the numerical range at one stage may be optionally combined with the upper or lower limit of the numerical range at another stage. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "A or B" may include either A or B, and may include both. Unless otherwise specified, the materials exemplified in the present specification may be used alone or in combination of two or more. The content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. The term "process" is included in this term not only in an independent process but also in the case where the intended action of the process is achieved even if it cannot be clearly distinguished from other processes. Since the specific density changes depending on the temperature, it is defined in the present specification as the specific density converted at 20 ° C.

FIG. 1 is a perspective view showing the overall configuration and internal structure of the lead storage battery (liquid type lead storage battery) according to the present embodiment. As shown in FIG. 1, the lead-acid battery 1 according to the present embodiment includes an electric tank 2 having an open upper surface and a lid 3 for closing the opening of the electric tank 2. The battery case 2 and the lid 3 are made of polypropylene, for example. The lid 3 is provided with a positive electrode terminal 4, a negative electrode terminal 5, and a liquid port plug 6 for closing the liquid injection port provided in the lid 3.

Inside the battery case 2, there are an electrode group 7, a positive electrode column (not shown) connecting the electrode group 7 to the positive electrode terminal 4, a negative electrode column 8 connecting the electrode group 7 to the negative electrode terminal 5, and an electrolytic solution. Is housed. The electrolytic solution contains, for example, sulfuric acid. The electrolytic solution may further contain aluminum ions. The electrolytic solution containing aluminum ions can be obtained, for example, by mixing sulfuric acid and aluminum sulfate.

FIG. 2 is a perspective view showing the electrode group 7. As shown in FIG. 2, the electrode group 7 includes a positive electrode plate (positive electrode) 9, a negative electrode plate (negative electrode) 10, and a separator 11 arranged between the positive electrode plate 9 and the negative electrode plate 10. The positive electrode plate 9 has a positive electrode current collector 13 and a positive electrode active material filling portion 14, and the positive electrode active material is filled in the positive electrode current collector 13 to form the positive electrode active material filling portion 14. There is. The negative electrode plate 10 has a negative electrode current collector 15 and a negative electrode active material filling portion 16, and the negative electrode active material is filled in the negative electrode current collector 15 to form a negative electrode active material filling portion 16. There is. In the present specification, the positive electrode plate after chemical conversion from which the positive electrode current collector is removed is referred to as "positive electrode active material", and the negative electrode plate after chemical conversion from which the negative electrode current collector is removed is referred to as "negative electrode active material". ..

The electrode group 7 has a structure in which a plurality of positive electrode plates 9 and negative electrode plates 10 are alternately laminated in a direction substantially parallel to the opening surface of the electric tank 2 via a separator 11. The number of the positive electrode plate 9 and the negative electrode plate 10 in the electrode group 7 may be, for example, 7 negative electrode plates with respect to 6 positive electrode plates.

In the electrode group 7, the selvage portions 9a of the plurality of positive electrode plates 9 are collectively welded by the positive electrode side strap 17. Similarly, the selvage portions 10a of the plurality of negative electrode plates 10 are collectively welded by the negative electrode side strap 18. Then, each of the positive electrode side strap 17 and the negative electrode side strap 18 is connected to the positive electrode terminal 4 and the negative electrode terminal 5 via the positive electrode column and the negative electrode column 8.

The separator 11 is formed in a bag shape, and the negative electrode plate 10 is housed in the separator 11. FIG. 3 is a diagram showing a bag-shaped separator 11 and a negative electrode plate 10 housed in the separator 11. FIG. 4 is a diagram showing an example of a separator. FIG. 4A is a front view showing a sheet-like object 20 used for manufacturing the bag-shaped separator 11, and FIG. 4B is a cross-sectional view of the sheet-like object 20. FIG. 5 is a cross-sectional view of the separator 11 and the electrode plate (positive electrode plate 9 and negative electrode plate 10).

As shown in FIG. 4, the sheet-shaped object 20 includes a flat plate-shaped base portion 21, a plurality of convex ribs 22, and mini ribs 23. The base portion 21 supports the rib 22 and the mini rib 23. A plurality of ribs 22 are formed so as to extend in the longitudinal direction of the sheet-like object 20 at the center in the width direction of the sheet-like object 20. The plurality of ribs 22 are arranged substantially parallel to each other on one surface 20a of the sheet-like object 20. One end of the rib 22 in the height direction is integrated with the base portion 21, and the other end of the rib 22 in the height direction is in contact with the positive electrode plate 9 (see FIG. 5). The base portion 21 faces the positive electrode plate 9 in the height direction of the rib 22. No rib is arranged on the other surface 20b of the sheet-like material 20, and the other surface 20b of the sheet-like material 20 is in contact with the negative electrode plate 10 (see FIG. 5).

Next, the details of the positive electrode plate 9 and the negative electrode plate 10 will be described.

The positive electrode active material contains PbO ₂ as a Pb component, and further contains a Pb component other than PbO ₂ (for example, PbSO ₄ ) and an additive described later, if necessary. As will be described later, the positive electrode active material is obtained by aging and drying a positive electrode active material paste containing a raw material for the positive electrode active material to obtain an unchemical positive electrode active material, and then forming an unchemicald positive electrode active material. be able to. The raw material of the positive electrode active material is not particularly limited, and examples thereof include lead powder. The lead powder is, for example, lead powder produced by a ball mill type lead powder manufacturing machine or a barton pot type lead powder manufacturing machine (in a ball mill type lead powder manufacturing machine, a mixture of powder of the main component PbO and scaly metal lead). ). Lead tan (Pb ₃ O ₄ ) may be added as a raw material for the positive electrode active material.

The content of the Pb component in the positive electrode active material may be 90 to 100% by mass based on the total mass of the positive electrode active material. The positive electrode active material contains at least β-PbO ₂ as a Pb component. The positive electrode active material may contain α-PbO ₂ and may not contain α-PbO ₂ . The content of the positive electrode active material may be 40 to 60% by mass based on the total mass of the positive electrode plate.

The positive electrode current collector serves as a conductive path for the current from the positive electrode active material and holds the positive electrode active material. The positive electrode current collector has, for example, a grid pattern. Examples of the composition of the positive electrode current collector include lead alloys such as lead-calcium-tin alloys and lead-antimony-arsenic alloys. Selenium, silver, bismuth and the like may be appropriately added to the positive electrode current collector depending on the intended use. A positive electrode current collector can be obtained by forming these lead alloys in a grid pattern by a gravity casting method, an expanding method, a punching method, or the like.

In the process of manufacturing the positive electrode plate, for example, the positive electrode active material paste is filled in the positive electrode current collector and then aged and dried to obtain a positive electrode plate having an unchemicald positive electrode active material. The unchemical positive electrode active material may contain tribasic lead sulfate as a main component. The positive electrode active material paste contains, for example, a raw material for the positive electrode active material, and may further contain other predetermined additives and the like.

Examples of the additive contained in the positive electrode active material paste include carbon materials (excluding carbon fibers) and reinforcing short fibers (acrylic fibers, polyethylene fibers, polypropylene fibers, polyethylene terephthalate fibers, carbon fibers, etc.). Examples of the carbon material include carbon black and graphite. Examples of carbon black include furnace black, channel black, acetylene black, thermal black and ketjen black.

When producing the positive electrode active material paste, lead powder can be used as a raw material for the positive electrode active material. Further, from the viewpoint of shortening the chemical conversion time, lead tan (Pb ₃ O ₄ ) may be added as a raw material for the positive electrode active material. By filling the positive electrode active material paste in a positive electrode current collector (for example, a positive electrode current collector lattice) and then aging and drying, a positive electrode plate having an unchemical positive electrode active material can be obtained. In the positive electrode active material paste, the blending amount of the reinforcing short fibers may be 0.005 to 0.3% by mass based on the total mass of the raw materials of the positive electrode active material.

The positive electrode active material can be obtained, for example, by the following method. First, additives such as reinforcing short fibers are added to the lead powder and mixed in a dry manner. Next, 4 to 10% by mass of water and 5 to 10% by mass of dilute sulfuric acid (specific gravity 1.28) are added to the mixture containing the lead powder and kneaded to prepare a positive electrode active material paste. Dilute sulfuric acid (specific gravity 1.28) may be added gradually in several portions in order to reduce heat generation. In the preparation of the positive electrode active material paste, sudden heat generation forms a positive electrode active material having a sparse structure, and the bonding force between the active materials during the life is reduced. Therefore, it is desirable to suppress the heat generation as much as possible.

The positive electrode active material can be obtained by aging and drying a positive electrode active material paste containing a raw material for the positive electrode active material to obtain an unchemicald positive electrode active material, and then chemicalizing the unchemicald positive electrode active material. The positive electrode active material contains, for example, α-PbO ₂ and β-PbO ₂ .

By filling the positive electrode current collector (casting lattice, expanded lattice, etc.) with the positive electrode active material paste and then aging and drying, a positive electrode plate having an unchemical positive electrode active material can be obtained. In the positive electrode active material paste, the blending amount of the reinforcing short fibers is 0.05 to 0.3% by mass based on the total mass of lead powder (the total mass of lead powder and lead tan when lead tan is contained). You can do it.

The aging conditions may be 15 to 60 hours in an atmosphere with a temperature of 35 to 85 ° C. and a humidity of 50 to 98 RH%. The drying conditions may be 15 to 30 hours at a temperature of 45 to 80 ° C.

The negative electrode active material contains at least Pb as a Pb component, and if necessary, further contains a Pb component other than Pb (for example, PbSO ₄ ) and an additive described later. The negative electrode active material may contain porous spongy lead. As will be described later, the negative electrode active material is obtained by aging and drying a negative electrode active material paste containing a raw material for the negative electrode active material to obtain an unchemicald negative electrode active material, and then forming an unchemicald negative electrode active material. be able to. The raw material for the negative electrode active material is not particularly limited, and examples thereof include lead powder. The lead powder is, for example, lead powder produced by a ball mill type lead powder manufacturing machine or a barton pot type lead powder manufacturing machine (in a ball mill type lead powder manufacturing machine, a mixture of powder of the main component PbO and scaly metal lead). ).

The negative electrode current collector serves as a conductive path for the current from the negative electrode active material and holds the negative electrode active material. The composition of the negative electrode current collector may be the same as the composition of the positive electrode current collector described above.

In the process of manufacturing a negative electrode plate, for example, a negative electrode active material paste is filled in a negative electrode current collector (for example, a negative electrode current collector lattice) and then aged and dried to obtain a negative electrode plate having an unchemical negative electrode active material. .. As the negative electrode current collector, the same one as the positive electrode current collector can be used. The unchemical negative electrode active material may contain tribasic lead sulfate as a main component. The negative electrode active material paste contains, for example, a raw material for the negative electrode active material and a resin having a sulfo group and / or a sulfonic acid base, and may further contain other predetermined additives and the like.

The negative electrode active material paste may further contain a solvent and sulfuric acid. Examples of the solvent include water (for example, ion-exchanged water) and an organic solvent.

Resins having a sulfo group and / or a sulfonic acid base include lignin sulfonic acid, lignin sulfonate, and a condensate of phenols, aminoaryl sulfonic acid, and formaldehyde (for example, bisphenol, aminobenzene sulfonic acid, and formaldehyde. It may be at least one selected from the group consisting of (condensates of).

Examples of the additive contained in the negative electrode active material paste include barium sulfate, carbon material (excluding carbon fiber) and short reinforcing fiber (acrylic fiber, polyethylene fiber, polypropylene fiber, polyethylene terephthalate fiber, carbon fiber, etc.). .. Examples of the carbon material include carbon black and graphite. Examples of carbon black include furnace black, channel black, acetylene black, thermal black and ketjen black.

The negative electrode active material paste can be obtained, for example, by the following method. First, a mixture is obtained by mixing a resin having a sulfo group and / or a sulfonic acid base with lead powder and an additive added as needed. Next, sulfuric acid (dilute sulfuric acid or the like) and a solvent (water or the like) are added to this mixture and kneaded to obtain a negative electrode active material paste.

When barium sulfate is used in the negative electrode active material paste, the blending amount of barium sulfate may be 0.01 to 1% by mass based on the total mass of the raw materials of the negative electrode active material. When a carbon material is used, the blending amount of the carbon material may be 0.01 to 2% by mass or 0.05 to 1.5% by mass based on the total mass of the raw material of the negative electrode active material. , 0.1 to 1.5% by mass, 0.2 to 1.4% by mass, 0.2 to 1% by mass, 0.2 to 0.5% by mass. It may be 0.2 to 0.3% by mass, and may be 0.2 to 0.25% by mass. The blending amount of the resin having a sulfo group and / or a sulfonic acid base may be 0.01 to 2% by mass in terms of resin solid content based on the total mass of the raw material of the negative electrode active material, and may be 0.05 to 0.05. It may be 1.5% by mass, 0.1 to 1% by mass, 0.15 to 0.5% by mass, or 0.2 to 0.4% by mass.

The aging conditions may be 15 to 60 hours in an atmosphere with a temperature of 35 to 85 ° C. and a humidity of 50 to 98 RH%. The drying conditions may be 15 to 30 hours at a temperature of 45 to 80 ° C.

The lead-acid battery according to this embodiment can be used for an electric vehicle. The electric vehicle according to the present embodiment includes the lead storage battery according to the present embodiment. The lead-acid battery according to the present embodiment can be used for a micro-hybrid vehicle such as an ISS vehicle and a power generation control vehicle. The micro-hybrid vehicle according to the present embodiment (for example, an ISS vehicle and a power generation control vehicle) includes a lead storage battery according to the present embodiment.

The lead-acid battery according to the present embodiment is charged at a constant voltage in a partially charged state (intermediate charge state, hereinafter referred to as “PSOC state”; PSOC: Partial State of Charge). As will be described later, the constant voltage charging includes at least one step in which the average value of the absolute values of the difference between the unipolar potential of the positive electrode in the PSOC state and the unipolar potential of the positive electrode in the overcharged state satisfies a specific range. .. The details will be described below.

Assuming that the overvoltage when the voltage V _c is applied to the lead storage battery is η ⁺ (positive electrode) and η ⁻ (negative electrode), the following equations (a) and (b) hold (E ₀ : electromotive current (temporarily open). Circuit voltage), I ⁺ _total : Total current of the positive electrode (sum of currents derived from the electron transfer reaction occurring at the positive electrode), I ^- _total : Total current of the negative electrode (sum of currents derived from the electron transfer reaction occurring at the negative electrode) )).
V _c = η ^＋ ＋ η ^－ ＋ E ₀・ ・ ・ (a)
I ⁺ _total = I ^- _total ... (b)

The electromotive force E ₀ of a single cell in a lead storage battery is about 2.1 V, and the overvoltage when 2.3 V is applied as the voltage V _c is 0.2 V. In this case, the formula (a) is "2.3V = 0.2V + 2.1V" and "η ⁺ + η ⁻ = 0.2V". Here, this 0.2V is allocated to the positive electrode and the negative electrode so as to have a total of 0.2V and satisfy the formula (b).

In a lead-acid battery, current flows when electrons generated at the negative electrode are received by the positive electrode. In this case, as shown in equation (b), the rate at which electrons are generated at the negative electrode is equal to the rate at which electrons are received at the positive electrode.

In charging a lead-acid battery in the PSOC state, gas generation (positive electrode: oxygen generation, negative electrode: hydrogen generation) occurs as a major side reaction in addition to the charging reaction of the active material. I ⁺ _total is the sum of the currents derived from these electron transfer reactions (charging reaction and side reaction of the active material) at the positive electrode, and I ^- _total is these electron transfer reactions (charging of the active material) at the negative electrode. It is the sum of the currents derived from the reaction and the side reaction), and the formula (b) is converted into the following formula (c) (I ⁺ _CHA : the current derived from the charging reaction of the active material at the positive electrode, I ⁺ _O2 . : Oxygen generation current at the positive electrode, I ^- _CHA : Current derived from the charging reaction of the active material at the negative electrode, I ^- _H2 : Hydrogen generation current at the negative electrode).
I ⁺ _CHA + I ⁺ _O2 = I ^- _CHA + I ^- _H2 ... (c)

On the other hand, in the overcharged state, since the charge is from the fully charged state, no active material remains to be charged. Therefore, since the charging reaction of the active material does not occur (I ⁺ _CHA = I ⁻ _CHA = 0), the following formula (d) is derived from the above formula (c).
I ⁺ _O2 = I ^- _H2 ... (d)

That is, in the overcharged state, the oxygen-evolving current and the hydrogen-evolving current are equal as shown in the equation (d), whereas in the PSOC state, the equation (c) should hold, and the oxygen-evolving current and the hydrogen-evolving current are generated. It does not have to be equal to the current. In this case, the overvoltage when the oxygen evolution current and the hydrogen evolution current are not equal in the PSOC state is different from the overvoltage when the oxygen evolution current and the hydrogen evolution current are equal. That is, in the _PSOC state and the overcharged state, even if the same voltage Vc is applied to each other, different overvoltages can occur. Therefore, there may be no correlation between the liquid reduction performance in the overcharged state and the liquid reduction performance in the PSOC state during actual use.

On the other hand, the present inventor examined the relationship between overvoltage and current. FIG. 6 is a diagram showing an example of a current-voltage curve (IV curve) when an overvoltage of 0.2 V is applied to a lead storage battery in an overcharged state. The curve in the figure is an approximate curve. At the time when the oxygen evolution current and the hydrogen generation current are equal (in the figure, reference numeral A; hereinafter referred to as “condition A”), the overvoltage of the positive electrode is 0.09V, the overvoltage of the negative electrode is −0.11V, and the positive electrode is positive. The amount of current in the negative electrode is 0.35 A, and the total amount of current used to generate oxygen and hydrogen (hereinafter referred to as “total current amount”) is 0.70 A. As the total current amount increases, the amount of gas generated increases and the amount of electrolytic solution reduced increases.

Here, in order to consider the effect that the overvoltage in the PSOC state is different from the overvoltage in the overcharged state on the depleted amount of the electrolytic solution, the current-voltage curves of the oxygen generated current and the hydrogen generated current are the PSOC state and the overcharged state. Assuming that the above is the same, the total current amount (index of the amount of liquid reduction) when the amount allocated to the positive electrode and the negative electrode of the overvoltage 0.2V fluctuates by 0.05V with respect to the above condition A will be examined. That is, when the amount of overvoltage allocated is shifted by 0.05 V to the positive charge side (positive electrode: 0.14 V, negative electrode: −0.06 V. In the figure, reference numeral B; hereinafter referred to as “condition B”), oxygen is generated in the positive electrode. The current is 1.00 A, the hydrogen generation current at the negative electrode is 0.14 A, and the total current amount is 1.14 A. When the overvoltage allocation amount deviates by 0.05 V to the negative charge side (positive electrode: 0.04 V, negative electrode: -0.16 V. In the figure, reference numeral C; hereinafter referred to as “condition C”), the oxygen generation current at the positive electrode is It is 0.12A, the hydrogen generation current at the negative electrode is 0.86A, and the total current amount is 0.98A. Since the total current amount of the condition B and the condition C is larger than the total current amount of the condition A, when the battery is charged under the condition B or the condition C, the electrolytic solution associated with the gas generation is charged more than when the battery is charged under the condition A. The amount of liquid reduction increases. As described above, when the overvoltage in the PSOC state is different from the overvoltage in the overcharged state, the amount of reduction of the electrolytic solution in the PSOC state becomes larger than that in the overcharged state.

On the other hand, the present inventor has the same voltage (the difference between the unipolar potential of the positive electrode and the unipolar potential of the negative electrode is the same) from the viewpoint of bringing the unipolar potential in the charging in the PSOC state closer to the unipolar potential in the overcharged state. By reducing the difference between the unipolar potential in the PSOC state and the unipolar potential in the overcharged state in a certain state), electrolysis in the PSOC state with respect to the reduced amount of the electrolytic solution in the overcharged state in comparison at the same voltage. It was found that it is possible to suppress the deviation of the reduced amount of the liquid. In this case, the overvoltage in the PSOC state is different from the overvoltage in the overcharged state, so that the overvoltage of one electrode is increased and the decrease amount (gas generation amount) of the electrolytic solution in the electrode is suppressed from increasing exponentially. Since it is possible, it is possible to suppress the deviation of the reduced amount of the electrolytic solution in the PSOC state from the reduced amount of the electrolytic solution in the overcharged state in comparison at the same voltage.

The overvoltage and the unipolar potential satisfy "overvoltage = unipolar potential-open circuit potential". Since the open circuit potential is less likely to fluctuate than the unipolar potential, the overvoltage can be easily adjusted based on the unipolar potential. By reducing the difference between the overvoltage in the PSOC state and the overvoltage in the overcharged state at the same voltage, the amount of the electrolytic solution in the PSOC state is reduced with respect to the amount of the electrolytic solution in the overcharged state in comparison with the same voltage. It is easy to prevent the liquid volume from diverging.

FIG. 7 is a diagram showing an example of a unipolar potential and a gas generation rate when a lead-acid battery in a PSOC state is charged at a constant voltage of 2.40 V. FIG. 7A shows the relationship between the charging time and the unipolar potential of the positive electrode. FIG. 7B shows the relationship between the charging time and the unipolar potential of the negative electrode. FIG. 7C shows the relationship between the charging time and the gas generation rate (the generation rate of the mixed gas of oxygen gas and hydrogen gas). In the example of FIG. 7, the unipolar potential of the positive electrode (solid line of (a) in FIG. 7) and the unipolar potential of the negative electrode (solid line of (b) in FIG. 7) in charging in the PSOC state are excessive at a voltage of 2.40 V. It is polarized to the positive side as compared with the unipolar potentials of the positive electrode and the negative electrode in the charged state (broken lines (a) and (b) in FIG. 7). In this case, by reducing the difference between the unipolar potential of the positive electrode in charging in the PSOC state and the unipolar potential of the positive electrode in the overcharged state at a voltage of 2.40 V (in this case, the unipolar potential of the negative electrode in charging in the PSOC state). The difference between the potential and the unipolar potential of the negative electrode in the overcharged state at a voltage of 2.40 V is also small), the amount of decrease in the electrolytic solution in the PSOC state (gas generation rate, solid line in FIG. 7C). The difference from the reduced amount of the electrolytic solution (gas generation rate; broken line in FIG. 7C) in the overcharged state can be reduced.

In the lead-acid battery according to the present embodiment, the unipolar potential A of the positive electrode obtained when the lead-acid battery in the PSOC state is constantly charged and the positive electrode in the overcharged state at the same voltage as the constant voltage charging voltage. The average value of the absolute value | AB | of the difference from the polar potential B is less than 0.07V. The method for charging a lead-acid battery according to the present embodiment is a method for charging a lead-acid battery that charges a lead-acid battery in a PSOC state at a constant voltage, and the unipolar potential A of the positive electrode obtained when the lead-acid battery is charged at the constant voltage and the constant voltage. The average value of the absolute value | AB | of the difference between the voltage of voltage charging and the unipolar potential B of the positive electrode in the overcharged state at the same voltage is less than 0.07V. That is, in the lead storage battery and the charging method thereof according to the present embodiment, "the average value of | AB | <0.07V" is satisfied. According to such a lead-acid battery and its charging method, it is possible to suppress the deviation of the reduced amount of the electrolytic solution in the PSOC state from the reduced amount of the electrolytic solution in the overcharged state in comparison at the same voltage. can.

In the method (evaluation method) for determining the liquid reduction performance of the lead-acid battery according to the present embodiment, the unipolar potential A of the positive electrode obtained when the lead-acid battery in the PSOC state is charged at a constant voltage is the same as the voltage of the constant voltage charge. The liquid-reducing performance of the lead-acid battery is determined based on the average value of the absolute value | AB | of the difference from the unipolar potential B of the positive electrode in the overcharged state at the voltage of. According to the method for determining the liquid-reducing performance of the lead-acid battery according to the present embodiment, the liquid-reducing performance in the PSOC state can be predicted (evaluated) based on the average value of the absolute value | AB |. The average value of the absolute value | AB | may be less than 0.07V. That is, in the method for determining the liquid reduction performance of the lead storage battery according to the present embodiment, when the average value of the absolute value | AB | is less than 0.07 V, the electrolytic solution in the overcharged state is compared at the same voltage. It can be determined that it is possible to suppress the deviation of the reduced amount of the electrolytic solution in the PSOC state with respect to the reduced amount of the liquid. The method for determining the liquid-reducing performance of the lead-acid battery according to the present embodiment may be performed during the charging step of charging the lead-acid battery in the PSOC state to a constant voltage. Further, after the charging step, a determination step of determining the liquid reduction performance of the lead storage battery may be performed based on the determination method of the liquid reduction performance of the lead storage battery according to the present embodiment.

The above-mentioned unipolar potential is the unipolar potential in the lead storage battery after chemical conversion. As the unipolar potential, for example, a potential for a mercury / mercuric sulfate primary mercury electrode (reference electrode) can be used. When the lead-acid battery includes a plurality of single cells (single cells), the unipolar potential of the positive electrode means the unipolar potential of the positive electrode of at least one single cell. When the lead-acid battery has a plurality of single-pole batteries, it is sufficient that the lead-acid battery has at least one single-cell that satisfies the above-mentioned difference in unipolar potential, and all of the single-cells have the above-mentioned difference in unipolar potential. May be satisfied. When a single cell has a plurality of positive electrodes (for example, a positive electrode plate), the unipolar potential of the positive electrode means the average value of the unipolar potentials of the plurality of positive electrodes (potential of the positive electrode group). When a single cell has a plurality of positive electrodes, the potential of the member (for example, the positive electrode terminal 4 in FIG. 1 or the positive electrode side strap 17 in FIG. 2) that collects current from the plurality of positive electrodes is measured to obtain the positive electrode. A unipolar potential can be obtained. The unipolar potential of the positive electrode during charging in the PSOC state may be the same as or higher than the unipolar potential of the positive electrode in the overcharged state, and may be the same as or lower than the unipolar potential of the positive electrode in the overcharged state. good.

The average value of the absolute value | AB | of the difference between the unipolar potential A and the unipolar potential B is the unipolar potential of the positive electrode in constant voltage charging for the lead-acid battery in the PSOC state and the positive electrode in the overcharged state. It is the average value of the absolute value of the difference from the unipolar potential (the average value of the total charge time in the charge in the PSOC state). The unipolar potential A for obtaining the average value is, for example, a unipolar potential every 100 milliseconds.

The difference in unipolar potential can be adjusted by adjusting the ratio of the amounts of the positive electrode active material and the negative electrode active material, the types and amounts of various additives, and the like. For example, when the unipolar potential A is more positively polarized than the unipolar potential B, the difference in the unipolar potential is reduced by increasing the charge acceptability of the positive electrode relative to the negative electrode. Can be done. Specifically, the ratio of the amount of the positive electrode active material to the negative electrode active material is increased, the amount of the resin having a sulfo group and / or the sulfonic acid base in the negative electrode is reduced, and the amount of the carbon material in the negative electrode is reduced. As a result, the difference in unipolar potential can be reduced. The lower limit of the amount of the positive electrode active material is 120 parts by mass or more, 130 parts by mass or more, 140 parts by mass or more, or 150 parts by mass with respect to 100 parts by mass of the negative electrode active material from the viewpoint of easily reducing the difference in unipolar potential. It may be more than a part. The upper limit of the amount of the positive electrode active material is 300 parts by mass or less, 250 parts by mass or less, with respect to 100 parts by mass of the negative electrode active material, from the viewpoint of obtaining excellent battery performance (cycle characteristics, discharge characteristics, charge acceptability, etc.). Alternatively, it may be 200 parts by mass or less.

Constant voltage charging may be performed at a plurality of voltages. That is, the constant voltage charging may include a plurality of charging steps having different voltages, and at least the first charging step of the first voltage and the second charging step of the second voltage are performed in this order. You may be prepared. In this case, it is sufficient that the above-mentioned difference in unipolar potential is satisfied in at least one charging step, and the above-mentioned difference in unipolar potential may be satisfied in all charging steps. The constant voltage charging may include another charging step (for example, a third charging step) after the first charging step and the second charging step described above. For example, the third charging step may be a charging step of a third voltage different from the first voltage and the second voltage, and may be a charging step of the same voltage as the first voltage. When the voltage of the third charging step is the same as the first voltage, it is sufficient that the above-mentioned difference in unipolar potential is satisfied at least in the first charging step. Each charging step is not limited to being continuously performed, and other steps (constant current charging step, discharging step, resting step, etc.) may be performed between the charging steps.

When constant voltage charging is performed at a plurality of voltages, from the viewpoint of further suppressing the deviation of the reduced amount of the electrolytic solution in the PSOC state from the reduced amount of the electrolytic solution in the overcharged state in comparison at the same voltage. , The average value of the absolute values of the differences in unipolar potentials in the plurality or all charging steps is preferably less than 0.07V. That is, when the constant voltage charging includes the above-mentioned first charging step and the second charging step, the absolute difference in unipolar potential in the entire charging step (first charging step and second charging step) is absolute. It is preferable that the average value of the values is less than 0.07V.

The average value of the absolute value of the difference in unipolar potential is a viewpoint that further suppresses the deviation of the reduced amount of the electrolytic solution in the PSOC state from the reduced amount of the electrolytic solution in the overcharged state in comparison at the same voltage. Therefore, it may be 0.06 V or less, 0.05 V or less, 0.04 V or less, 0.03 V or less, 0.02 V or less, 0.01 V or less, or 0 V. When constant voltage charging is performed at a plurality of voltages, from the viewpoint of further suppressing the deviation of the reduced amount of the electrolytic solution in the PSOC state from the reduced amount of the electrolytic solution in the overcharged state in comparison at the same voltage. It is preferable that the average value of the absolute values of the differences in the unipolar potentials in the plurality or all charging steps satisfies these ranges.

The conditions for constant voltage charging are not particularly limited. The voltage for constant voltage charging (voltage for a single cell) may be, for example, 2.15 to 2.80 V. The temperature at the time of constant voltage charging may be, for example, 5 to 80 ° C. Constant voltage charging can be performed, for example, at a voltage of 2.40 V and 60 ° C. for a single cell based on the storage battery standard of a 14.4 V battery established by the German Association of the Automotive Industry (VDA: Verband der Automobilindustrie). The time for constant voltage charging (time for maintaining one voltage) may be, for example, 1 second to 21 days.

The PSOC state and the adjustment procedure thereof when starting constant voltage charging are not particularly limited. For example, the fully charged state may be 100%, and the charged state may be 90% or more.

The unipolar potential of the positive electrode in the overcharged state is, for example, the unipolar potential when constantly charged at a constant voltage in the overcharged state, and has a constant potential. As the voltage in this case, the same voltage as the voltage for constant voltage charging in the PSOC state is used. The unipolar potential of the positive electrode in the overcharged state is the unipolar potential at the same temperature as the unipolar potential of the positive electrode in the PSOC state.

For the amount of reduction of the electrolytic solution (magnitude of the amount of reduction) in the overcharged state and the PSOC state, for example, the blending amount of the carbon material, the sulfo group and / or the resin having a sulfonic acid base in the negative electrode is adjusted. Can be adjusted by. On the surface of the carbon material, hydrogen generation tends to proceed more easily than the Pb component. Therefore, by reducing the blending amount of the carbon material, it is possible to reduce the amount of reduction of the electrolytic solution due to hydrogen generation. Further, when the negative electrode contains a resin having a sulfo group and / or a sulfonic acid base in addition to the carbon material, the resin having a sulfo group and / or a sulfonic acid base is adsorbed on the carbon material to generate hydrogen. It can be suppressed and the amount of decrease in the electrolytic solution due to hydrogen generation can be reduced. From this point of view, when the negative electrode contains a carbon material, the negative electrode may contain a carbon material and a resin having a sulfo group and / or a sulfonic acid base.

In the method for determining the liquid-reducing performance of the lead-acid battery according to the present embodiment, from the viewpoint of easily predicting the liquid-reducing performance in the PSOC state, the overvoltage of the positive electrode obtained when the lead-acid battery in the PSOC state is charged at a constant voltage and the above-mentioned constant. The liquid-reducing performance of the lead-acid battery may be determined based on the average value of the absolute value of the difference between the voltage of voltage charging and the overvoltage of the positive electrode in the overcharged state at the same voltage. In the lead-acid battery according to the present embodiment, from the viewpoint of easily suppressing the deviation of the reduced amount of the electrolytic solution in the PSOC state from the reduced amount of the electrolytic solution in the overcharged state in comparison with the same voltage, the PSOC state. The average value of the absolute value of the difference between the overvoltage of the positive electrode obtained when the lead-acid battery is constantly charged and the overvoltage of the positive electrode in the overcharged state at the same voltage as the constant voltage charging voltage is less than 0.07V. May be. The method for charging the lead-acid battery according to the present embodiment is from the viewpoint that it is easy to suppress the deviation of the reduced amount of the electrolytic solution in the PSOC state from the reduced amount of the electrolytic solution in the overcharged state in comparison with the same voltage. , A method for charging a lead-acid battery that charges a lead-acid battery in a PSOC state at a constant voltage, wherein the overvoltage of the positive electrode obtained when the lead-acid battery is charged at the constant voltage and the overcharge state at the same voltage as the voltage of the constant voltage charge. The average value of the absolute value of the difference from the overvoltage of the positive electrode may be less than 0.07V.

Hereinafter, the present disclosure will be specifically described with reference to Examples. However, the present disclosure is not limited to the following examples.

<Making lead-acid batteries>
(Example 1)
[Preparation of positive electrode current collector]
As a positive electrode current collector, a plate-shaped lead-calcium-tin alloy (lead content: 0.05% by mass, calcium content: 0.5% by mass) is cut and stretched so as to widen the cut. The expanded lattice body prepared in the above was prepared. The positive electrode current collector had a width of 145 mm, a height of 110 mm, and a thickness of 0.9 mm.

[Manufacturing of unchemical positive electrode plate]
To the lead powder prepared by the ball mill method, 0.07% by mass of reinforcing short fibers (acrylic fibers) and 0.01% by mass of sodium sulfate were added and then dry-mixed. The blending amount of each of the acrylic fiber and sodium sulfate is based on the total mass of the lead powder. Next, 10% by mass of water and 9% by mass of dilute sulfuric acid (specific gravity 1.28) were added to the mixture containing the lead powder and then kneaded to prepare a positive electrode active material paste (water and dilute sulfuric acid). Each compounding amount is based on the total mass of lead powder). When preparing the positive electrode active material paste, dilute sulfuric acid was added stepwise in order to avoid a rapid temperature rise. Subsequently, the prepared positive electrode active material paste was filled in the positive electrode current collector obtained above, and aged in an atmosphere of a temperature of 50 ° C. and a humidity of 98% for 24 hours. As a result, an unchemical positive electrode plate in which the positive electrode current collector was filled with the unchemical positive electrode active material was obtained. In the unchemical positive electrode plate, the width of the filled portion was 145 mm, the height of the filled portion was 110 mm, and the thickness was 1.5 mm.

[Manufacturing of negative electrode current collector]
As a negative electrode current collector, a plate-shaped lead-calcium-tin alloy (lead content: 0.05% by mass, calcium content: 0.5% by mass) is cut and stretched so as to widen the cut. The expanded lattice body prepared in the above was prepared. The negative electrode current collector had a width of 145 mm, a height of 110 mm, and a thickness of 0.8 mm.

[Manufacturing of unchemical negative electrode plate]
To the lead powder prepared by the ball mill method, 0.1% by mass of reinforcing short fibers (acrylic fibers), 0.2% by mass of acetylene black, and 1.0% by mass of barium sulfate were added and then dry-mixed. The above-mentioned compounding amount is a compounding amount based on the total mass of lead powder. Next, 0.2% by mass of lignin sulfonate (trade name: Vanillex N, manufactured by Nippon Paper Industries, Ltd.) (in terms of resin solid content, the amount is based on the total mass of lead powder) and 10% by mass of water. % (The blending amount based on the total mass of lead powder) was added and then kneaded. Subsequently, 9.5% by mass of dilute sulfuric acid (specific gravity 1.280) was added little by little based on the total mass of the lead powder and kneaded to prepare a negative electrode active material paste. Subsequently, the prepared negative electrode active material paste was filled in the negative electrode current collector obtained above, and aged in an atmosphere of a temperature of 50 ° C. and a humidity of 98% for 20 hours. As a result, an unchemical negative electrode plate in which the negative electrode current collector was filled with the unchemical negative electrode active material was obtained. In the unchemical negative electrode plate, the width of the filled portion was 145 mm, the height of the filled portion was 110 mm, and the thickness was 1.3 mm.

[Preparation of separator]
A separator (bag) formed by processing a sheet-like material having a plurality of convex ribs on one surface and a base portion supporting the ribs into a bag shape so that the surface on which the ribs are formed is on the outside. (See FIGS. 3 and 4). In the separator, the total thickness is 0.8 mm, the thickness T of the base portion is 0.2 mm, the height H of the rib is 0.6 mm, the upper base width B of the rib is 0.4 mm, and the rib. The bottom width A was 0.8 mm.

[Battery assembly]
An unchemical negative electrode plate was housed in the obtained bag-shaped separator. Next, 6 unchemical positive electrode plates and 7 unchemical negative electrode plates housed in a bag-shaped separator were alternately laminated so that the ribs of the separator were in contact with the unchemical positive electrode plates. In the above-mentioned production of the electrode plates, the total amount of the positive electrode active material in the six positive electrode plates was adjusted to 150 parts by mass with respect to 100 parts by mass of the total amount of the negative electrode active material in the seven negative electrode plates. Next, the current collecting portion of the unchemical positive electrode plate and the current collecting portion of the unchemical negative electrode plate were collectively welded to the positive electrode side strap and the negative electrode side strap for each polarity to obtain a electrode plate group. The thickness of the electrode plate group was 3.36 cm.

An electric tank having one cell chamber was prepared. After inserting the electrode plates into the cell chamber of the electric tank, the lid was heat-welded to the electric tank. Then, the liquid spout was opened, and dilute sulfuric acid (electrolyte) was poured into the cell from the liquid pouring port provided on the lid. Next, an electric tank was formed by energizing the battery at an ambient temperature of 40 ° C. and a current of 25 A for 20 hours to produce a single-cell lead-acid battery (corresponding to a D23 size single cell specified in JIS D5301). The specific gravity of the electrolytic solution after chemical conversion was adjusted to 1.29. The content of Pb component in the positive electrode after chemical conversion (based on the total mass of the positive electrode active material) is 99.9% by mass, and the content of the Pb component in the negative electrode after chemical conversion (based on the total mass of the negative electrode active material) is 98. It was 4% by mass.

(Example 2)
The total amount of positive electrode active material was reduced, and the total amount of positive electrode active material in 6 positive electrode plates was adjusted to 118 parts by mass with respect to 100 parts by mass of the total amount of negative electrode active material in 7 negative electrode plates. A lead-acid battery was produced in the same manner as in Example 1 except that the amount of acetylene black used was changed to 0.05% by mass.

(Example 3)
The total amount of positive electrode active material was reduced, and the total amount of positive electrode active material in 6 positive electrode plates was adjusted to 118 parts by mass with respect to 100 parts by mass of the total amount of negative electrode active material in 7 negative electrode plates. A lead-acid battery was prepared in the same manner as in Example 1 except that the amount of the lignin sulfonate used was changed to 0.3% by mass.

(Example 4)
The total amount of positive electrode active material was reduced, and the total amount of positive electrode active material in 6 positive electrode plates was adjusted to 118 parts by mass with respect to 100 parts by mass of the total amount of negative electrode active material in 7 negative electrode plates. A lead-acid battery was prepared in the same manner as in Example 1 except that the amount of the lignin sulfonate used was changed to 0.4% by mass.

(Example 5)
The total amount of positive electrode active material was increased, and the total amount of positive electrode active material in 6 positive electrode plates was adjusted to 300 parts by mass with respect to 100 parts by mass of the total amount of negative electrode active material in 7 negative electrode plates. A lead-acid battery was produced in the same manner as in Example 1 except that the amount of lignin sulfonate used was changed to 0.05% by mass and the amount of acetylene black used was changed to 0.3% by mass.

(Comparative Example 1)
The same as in Example 1 except that the total amount of the positive electrode active material was reduced and the total amount of the positive electrode active material in the 6 positive electrode plates was adjusted to 118 parts by mass with respect to 100 parts by mass of the total amount of the negative electrode active material in the 7 negative electrode plates. A lead storage battery was manufactured.

(Comparative Example 2)
A lead-acid battery was produced in the same manner as in Example 1 except that the amount of lignin sulfonate used was changed to 0.05% by mass in the production of the unchemical negative electrode plate.

(Comparative Example 3)
A lead-acid battery was produced in the same manner as in Example 1 except that the amount of acetylene black used was changed to 0.4% by mass in the production of the unchemical negative electrode plate.

(Comparative Example 4)
The same as in Example 1 except that the total amount of the positive electrode active material was increased and the total amount of the positive electrode active material in the 6 positive electrode plates was adjusted to 300 parts by mass with respect to 100 parts by mass of the total amount of the negative electrode active material in the 7 negative electrode plates. A lead storage battery was manufactured.

<Evaluation of liquid reduction performance>
After overcharging the lead-acid battery at a constant voltage of 2.40 V for 24 hours at an ambient temperature (air tank temperature) of 60 ° C., the unipolar potential of the positive electrode (hereinafter referred to as “positive electrode potential”) is overcharged. The positive electrode potential in is constant) was measured. The positive electrode potential was determined by measuring the potential difference between the positive electrode terminal and the reference electrode. A mercury / mercuric sulfate primary mercury electrode was used as the reference electrode.

In addition, the flow rates of oxygen gas and hydrogen gas generated from the battery were measured by the following procedure. First, a tube was connected to the battery so that the generated gas would not leak. Next, oxygen gas and hydrogen gas are collected, and a hydrogen concentration meter (HPS-100, manufactured by AMS), a gas flow meter (F-100D, DP-FLOW, manufactured by Bronkhorst) and an oxygen concentration connected in series to each other are collected. Oxygen gas and hydrogen gas were introduced into a meter (GMH3695 / GGO370, manufactured by Greiser), and the flow rate, oxygen concentration and hydrogen concentration of the mixed gas were measured. Then, the flow rates of the oxygen gas and the hydrogen gas were obtained by multiplying the flow rate of the mixed gas by the concentration of each gas (oxygen concentration or hydrogen concentration). Based on these flow rates, the rate of liquid reduction by electrolysis of water was determined as the amount of liquid reduction in the overcharged state.

Subsequently, at an ambient temperature (air tank temperature) of 60 ° C., 10% of the battery capacity of the lead-acid battery after overcharging was discharged to adjust the state of charge to 90%. Next, after standing for 12 hours, it was charged at a constant voltage of 2.40 V for 1 hour. During this 1-hour constant voltage charge, the positive electrode potential was measured every 100 milliseconds by the same method as in the above-mentioned overcharge state. In addition, the flow rates of oxygen gas and hydrogen gas generated from the battery were measured by the same method as in the overcharged state described above. Based on these flow rates, the rate of liquid reduction by electrolysis of water was determined as the amount of liquid reduction in the PSOC state.

Next, after calculating the absolute value of the difference between the positive electrode potential in the overvoltage state and the positive electrode potential every 100 milliseconds at the time of constant voltage charging for 1 hour in the PSOC state, the average value of the absolute values was obtained. Table 1 shows the unipolar potential (positive electrode potential), the difference in unipolar potential (the average value of the absolute values of the difference in unipolar potential), and the liquid reduction rate (liquid reduction performance) in the overcharged state and the PSOC state. The liquid reduction performance was relatively evaluated with the measurement result of Comparative Example 1 in the overcharged state as 100. The smaller the liquid reduction rate, the better the liquid reduction performance.

In the embodiment, the difference between the unipolar potential A of the positive electrode obtained when the lead-acid battery in the PSOC state is constantly charged at a voltage of 2.40 V and the unipolar potential B of the positive electrode in the overcharged state at a voltage of 2.40 V. Since the average value of the absolute value | AB | is small, the amount of the electrolytic solution reduced in the PSOC state is compared with the amount of the electrolytic solution reduced in the overcharged state in comparison at the same voltage (voltage: 2.40 V). Is suppressed from diverging. On the other hand, in the comparative example, since the average value of the absolute value | AB | of the difference in the unipolar potential is large, the amount of reduction of the electrolytic solution in the overcharged state in comparison with the same voltage (voltage: 2.40 V). On the other hand, the reduced amount of the electrolytic solution in the PSOC state is different.

1 ... Lead-acid battery, 9 ... Positive electrode plate (positive electrode), 10 ... Negative electrode plate (negative electrode).

Claims (4)

The absolute value of the difference between the unipolar potential of the positive electrode obtained when a partially charged lead-acid battery is charged at a constant voltage and the unipolar potential of the positive electrode in an overcharged state at the same voltage as the constant voltage charging voltage. A method for determining the liquid-reducing performance of a lead-acid battery, which determines the liquid-reducing performance of the lead-acid battery based on the average value. The determination method according to claim 1, wherein the average value is less than 0.07 V. The absolute value of the difference between the unipolar potential of the positive electrode obtained when a partially charged lead-acid battery is charged at a constant voltage and the unipolar potential of the positive electrode in an overcharged state at the same voltage as the constant voltage charging voltage. Lead-acid battery with an average value of less than 0.07V. It is a charging method for lead-acid batteries that charges a partially charged lead-acid battery at a constant voltage.
The average value of the absolute value of the difference between the unipolar potential of the positive electrode obtained when charging at the constant voltage and the unipolar potential of the positive electrode in the overcharged state at the same voltage as the constant voltage charging is 0.07V. Less than, how to charge a lead acid battery.

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