JPS6043632B2 - Lead acid battery and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead-acid battery using a wet process lead monoxide and a mixture of conductive lead oxide as an active material raw material, and a method for manufacturing the same.

Wet method described in U.S. Pat. No. 4,117,104, in which granules of lead monoxide, i.e., granules of metallic lead, a liquid medium, and oxygen are filled in a rotary mill, and granules of metallic lead are wetted with the liquid medium. Slurry is produced by rotating the rotary mill under conditions in which at least a portion of the material is located in the gas phase above the liquid level of the liquid medium and the metallic lead particles rub against each other through the liquid medium. The lead monoxide recovered is converted into monoacid using a dry method. It has properties significantly different from lead chloride, such as easy reactivity, fine particle size, and photostability. The present inventors have already proposed the use of this wet-process lead monoxide as an active material raw material for lead-acid batteries.

(Unexamined Japanese Patent Publication No. 54-10943) When this wet method method uses lead monoxide as an active material raw material, a lead-acid battery with a superior active material utilization rate can be produced compared to the case where conventional lead powder or surge is used. The above-mentioned publication discloses that the advantage that chemical conversion treatment can be achieved with a significantly smaller amount of electricity or electric power is achieved. The present inventors have discovered that the above-mentioned wet-processed lead monoxide has an electrical conductivity of 1 to 5% (in this specification, the term "conductive" is used to mean that it is more conductive than wet-processed lead monoxide). It shall be.

) When lead oxide is blended and used as an active material raw material,
In addition to further improving the utilization rate of active materials,
It has been found that chemical conversion treatment can be performed with even smaller amounts of electricity or electric power. According to the present invention, in a lead-acid battery including a chemically converted product of lead oxide or its sulfuric acid paste as an active material of an electrode, the lead oxide is
The true density of Cc, the primary particle size of 0.2 microns or less, the infrared absorption peak at wave numbers 1400 to 1410 crfL-1, and ? % or more of lead monoxide or a heat-treated product thereof, and (B) 1 to 50% by weight based on the lead monoxide, where X is a number from 0.1 to 0.9. It has a composition and a volume resistivity of 1 x 1 f' to 5 x 1010 Ω, and its interior is made of lead monoxide or a relatively highly oxidized lead oxide, and the surface portion is made of metallic lead or a relatively highly oxidized lead oxide. A lead-acid battery is provided, characterized in that it consists of a mixture of a conductive lead oxide of a lead shell type consisting of a low lead oxide.

An important feature of the present invention is that a lead shell type conductive lead oxide (1 to 5 weight percent, particularly 3 to 4 weight percent) is added to the wet process lead monoxide.
The purpose is to use a compound containing conductive lead oxide (hereinafter sometimes simply referred to as conductive lead oxide) as an active material raw material. A lead-acid battery manufactured using only wet-process lead monoxide as an active material raw material (hereinafter simply referred to as a wet-process lead-acid battery) is a lead-acid battery manufactured using a conventional active material raw material such as lead powder. has some properties that are not recognized. In other words, the wet method lead-acid battery shows a significantly superior active material utilization rate both in the initial discharge and in the fifth and subsequent discharges, but rather, the active material utilization rate gradually improves when discharges are repeated. Is recognized. Wet method lead monoxide is extremely fine, with a primary particle size of 0.2 microns or less, and has a low chromic anhydride reaction rate. % or more, but the chemical conversion treatment does not progress uniformly over the entire electrode plate, and repeated charging and discharging can cause chemical conversion even to the inside. It is presumed that the process will proceed. The reason for this is believed to be that wet-processed lead monoxide is extremely fine and compositionally pure lead monoxide, so sufficient conductivity cannot be obtained during chemical conversion treatment. In order to improve this drawback, a conductive agent is mixed with wet lead monoxide,
It is conceivable to allow the chemical conversion treatment to proceed sufficiently, but since such a conductive agent cannot serve as an active material, it is inevitable that the discharge capacity per weight of the electrode plate will decrease.

In the present invention, when the above-mentioned amount of conductive lead oxide is blended with wet lead monoxide, this lead oxide acts as a conductive agent during the chemical conversion treatment and is effectively converted into an active material. The chemical conversion treatment is promoted without reducing the discharge capacity of the battery, and the active material utilization rate in the initial discharge is significantly improved.

Furthermore, the amount of electricity or power required for chemical conversion treatment is also significantly reduced. If the blending amount of conductive lead oxide is less than the above range, it is difficult to sufficiently improve the active material utilization rate in the initial discharge, while if the blending amount is larger than the above range, When charging and discharging are repeated over a long period of time, the active material utilization rate is significantly lower than in the case of the present invention.

It is also extremely important that the conductive lead oxide used in the present invention has the composition of formula (1) above.

When the number of oxygen atoms per lead atom is greater than 0.9, it is difficult to sufficiently increase the conductivity in the mixture.
On the other hand, when it becomes smaller than 0.1, the ratio of lead converted into active material decreases, and the active material utilization rate and discharge capacity per electrode plate weight decrease. Although this conductive metal oxide differs depending on the shape and structure of its particles, it is measured by the method described below to be 1×1Cf3 to 5.
×1010Ω-α especially 1X107 to 5×1CPΩ-d
It is desirable to have a volume resistivity in the range of . The lead oxide having the composition of formula (1) is said to be a complex mixture of metallic lead, lead monoxide, or lead oxide in an intermediate oxidation state. Among these, a lead shell type lead oxide is used, in which the interior is made of lead monoxide or lead oxide with a relatively high degree of oxidation, and the surface is made of metallic lead or lead oxide with a low degree of oxidation.

``These lead shell-type lead oxides include those in which metallic lead or lower-order oxides form a continuous layer and those in which a discontinuous layer is formed.In the present invention, particles of either of these are used. However, it is particularly preferable to use a conductive lead oxide in which metallic lead or a low-order oxide exists as a discontinuous layer.In other words, the conductive lead oxide used in the present invention has a surface portion containing metallic lead or a low-order oxide. It has a structural feature in which a secondary oxide is formed, and because of this structure, the desired effects of conductive treatment and use of itself as an active material are achieved. The lead shell type conductive lead oxide is
It can be manufactured by a wet lead powder method or a lead monoxide reduction method.

The wet lead powder method involves filling a rotary mill with granular metal lead alone or a combination of this with a crushing medium such as balls or beads, a liquid medium, and a limited amount of oxygen. A method is used in which a rotary mill is rotated under conditions where the objects rub against each other or against the grinding media, thereby dispersing the lead powder into the liquid medium.

At this time, if a reducing agent such as tartaric acid or citric acid is contained in the liquid medium, the above-mentioned lead shell type oxide can be obtained.
Furthermore, lead monoxide can be chemically reduced using a reducing agent such as hydrogen, sulfurous acid, hydroxide, hydroxylamine, hydrazine, hydrogen peroxide, tartaric acid, citric acid, etc., cathodic reduction method, or using visible light, ultraviolet light, etc. Conductive lead oxide can be produced by photo-reduction method, and oxides produced by this method generally have a lead shell type structure.

The conductive lead oxide obtained by these methods may be subjected to the above-described reduction treatment or oxidation treatment in order to adjust the volume resistivity and oxygen atomic ratio to desired values.

The wet method lead monoxide used in the present invention is produced by filling a rotary mill with metal lead particles, a liquid medium, and oxygen: At least a part of the metal lead particles moistened with the liquid medium is The rotary mill is rotated under conditions where the metallic lead particles are located in the gas phase of Hijikata below the liquid level and rub against each other in the liquid medium. It is produced by forming a dispersion in which ultrafine particles of lead oxide are dispersed in a liquid medium.

The details of this manufacturing method and the physical properties of the product can be found in the aforementioned U.S. Pat.
This is described in Japanese Patent No. 10943, so please refer to this. Wet method lead monoxide includes Resurge type lead monoxide,
There are three types of lead monoxide, mashikotsuto lead monoxide and hydrated lead monoxide, any of which can be used for the purpose of the present invention. still,
The wet method lead monoxide used in the present invention further has a wave number of 1
400 to 141? It is characterized by having an infrared (IR) absorption peak at -1.

The attached drawing, Figure 2, shows the known yellow orthorhombic system PbO(7)IR.
Figure 3 shows the absorption spectrum of the known red tetragonal system P.
This is an IR absorption spectrum of lO, and it is clear that all known lead monoxides have virtually no absorption peak in the wavenumber range of 1400 to 14W x-1. On the other hand, Fig. 4 shows the mashikotsuto type lead monoxide used in the present invention (Reference Example 1, Sample No. A-1), and Fig. 5 shows the surge type lead monoxide used in the present invention (Reference Example 1, Sample No. A-1). No. A-2) and FIG. 6 are nail absorption spectra of hydrated lead monoxide (Reference Example 1, Sample No. A-3) used in the present invention, and both are remarkable at wave numbers 1400 to 1410 cfn-1. It will be understood that the absorption peaks are as follows. Furthermore, from the comparison of FIGS. 2 to 6, it can be seen that lead monoxide used in the present invention has a further remarkable feature of exhibiting sharp absorption at a wave number of approximately 68 1.

Conventionally, wave number around 1400c7n-1 and wave number 680cm
So-called lead carbonate is known as a lead compound having a ■ absorption peak at -1.

However, in each of the lead monoxide examples described above,
It is manufactured under conditions excluding carbon dioxide gas, and no lead carbonate is produced at all, and these wet process fine particles of lead monoxide have other absorption peaks specific to lead carbonate, such as wave number 840cTn-1. , 1052 α-1, 1732 礪-
The above-mentioned two absorption peaks are included in the present invention because they substantially do not have each absorption peak of 1 and exhibit an absorption peak at a wave number of around 490c7x-1, which is not observed at all in lead carbonate! This absorption peak can be said to be unique to lead monoxide, which is used in The wet method lead monoxide used in the present invention further includes:
? It is also clearly distinguishable from conventional lead monoxide in that it has a chromic anhydride reaction rate of % or more, particularly preferably 96% or more.

be able to. It is known that lead monoxide generally has a chromic anhydride reaction rate of 40 to 80, although it varies depending on the manufacturing method.
As is clear from the fact that it is within the range of %, the reactivity is inferior. On the other hand, the above-mentioned new lead monoxide has excellent reactivity that cannot be predicted, for example, 99
．． It shows a reaction rate (RC) of as high as 9%. Furthermore, as is clear from the examples described later, the wet process lead monoxide used in the present invention ranges from &3 to 9.2f/Cc.
It will be appreciated that the particles are extremely fine, having a true density of , and a primary particle size of less than 0.2 microns, particularly preferably less than 0.1 microns.

In addition, this wet process lead monoxide can be used as an active material raw material in the state as produced, that is, without undergoing thermal history, or it can be used as an active material raw material after being subjected to appropriate heat treatment. I can do it too.

The heat treatment can be carried out, for example, at a temperature of 30 to 450°C, or a temperature of 500 to 85°C, for a time of 0.5 to 12 times, particularly at a temperature of 90 to 400'C, for a time of 0.5 to 6 times, in one stage or in multiple stages. It can be carried out. In this case, the heat treatment temperature is a temperature at which it is difficult for Komyotan to form, especially 30 to 450°C or 60°C.
A range of 00 to 850'C is preferable in terms of the utilization rate of the active material. Of course, there is no problem even if this heat treatment causes transformation of the crystal type of lead oxide. The lead-acid battery of the present invention can be manufactured by means known per se, except that the aforementioned blend of wet process lead monoxide and conductive lead oxide is used.

Wet method The blending of lead monoxide and conductive lead oxide may be carried out by dry blending using a so-called blender, or by wet mixing using water or the like as a dispersion medium. In order to obtain an intimate blend of the two, the particle size of the conductive lead oxide is preferably in the range of 0.1 to 7 microns. For example, in the case of a paste-type battery, the above-mentioned blend is kneaded with sulfuric acid to prepare a sulfuric acid paste, this paste is filled into a grid, and then chemical conversion treatment is performed to produce an electrode plate. After chemical conversion treatment, it is assembled into a storage battery.

Pasting of this blend is carried out in substantially the same area as the pasting area of wet lead monoxide, i.e. y≦1820X'
-3694X+1897...(2) y≦2417e-
3.3x...(3)y≧111.3-105.3X-
0.7519...(4) ,>1
...(5) In the formula, x is the specific gravity (20°C) of sulfuric acid used for pasting, and y is PlOlO
The primary pasting area is within the range expressed by the amount (ml) of the sulfuric acid used per Oy, or y≧1
50(g)-2.77X...(6) In the formula, X and y have the above-mentioned meanings, and the process can be carried out in the secondary pasting area within the range represented by.

The amount of sulfuric acid used can vary within a wide range, depending on the type and type of plate, and is generally between 0.2 and 30 mol%, especially 1% by mole, based on the blend.
Preferably, sulfuric acid (H2SO4) is used in an amount of 20 to 20 mole percent, most preferably 6 to 15 mole percent.

To form a paste, the blend and dilute sulfuric acid are kneaded under the conditions described above, or the aqueous paste (or water-containing cake) of the blend is kneaded with dilute sulfuric acid having a relatively high specific gravity.

In this latter method, the water contained in the blend may be calculated as if it were contained in dilute sulfuric acid, and the above-mentioned conditions may be satisfied. When making a paste, known additives can be added in known amounts, such as glass fiber, rock wool, etc.
Reinforcement materials such as aromatic polyester or polyamide fibers:
Powder fillers such as silica, alumina, and aluminum silicate; conductive reinforcing materials such as carbon black and graphite fibers; negative plate shrinkage inhibitors such as barium sulfate; low-temperature rapid discharge performance improvers such as lignin; or ammonium carbonate, One or more water-soluble or acid-soluble inorganic salts such as soda carbonate, sodium sulfate, and ammonium sulfate may be blended in a small amount, for example, 0.01 to 1% by weight. Kneading can be carried out using various types of kneading machines such as edge runner type, pony type, and Wagner type, and it is generally preferable to knead for 2 to 6 times, particularly 5 to 3 times. The formed paste is then filled into the voids of the grid and dried.

The filling operation can be performed using a known automatic filling machine, and the drying can be performed by various methods such as natural drying, heat drying, and steam drying. As a grid, ammon is 3~
Cast products of lead-ammony alloy containing 8% by weight can be used, and the filling amount of the paste varies depending on the application, but is 2.5 to 5.0y/All based on PbO, especially 0.
3 to 4.5y/c! It is preferable to set it in the range of l. Also,
Although the thickness of the electrode plate may vary, it is generally desirable to have a thickness of 0.5 to 3", particularly 0.5 to 10" after chemical conversion treatment. Then fill with paste,
The dried electrode plates are arranged alternately in positive and negative directions in a tank, and energized in dilute sulfuric acid to electrolytically oxidize and reduce the paste to convert the paste into lead peroxide (PbO2), which is an active material, and spongy metal lead.

This chemical conversion treatment may be carried out in a so-called tank formation in a treatment tank or in a container formation carried out in a storage battery. For chemical conversion, dilute sulfuric acid, especially specific gravity (20℃
) of 1.05 to 1.15, or ammonia sulfate, etc., to 0.2717 to 1.
It is preferable to carry out at a current density of 5 A/d, especially 0.5 to 1.0 A/Dd.

According to the present invention, in connection with the use of wet process ultrafine particle lead monoxide, it is a significant advantage that the chemical conversion treatment can be performed with a significantly reduced amount of electricity or power (integrated power). For example, as shown in the comparative example below, when wet-process lead monoxide is used as an active material raw material, in order to completely convert the sulfuric acid paste of these raw materials into an active material consisting of lead dioxide, it is generally necessary to It is recognized that 1.5 to 2 times the amount of electricity is required. In contrast, according to the present invention,
Using the blends described above, even the theoretical quantity of electricity is sufficient to completely convert the sulfuric acid paste into an active material consisting of lead dioxide, generally between 1.1 and 1.
Chemical conversion treatment can be performed using only a small amount of electricity. According to the present invention, the electric power required for chemical conversion treatment can be significantly reduced compared to known methods, and the time required for chemical conversion treatment can also be significantly shortened, resulting in significant improvements in energy saving and productivity. benefits are achieved.

Conventionally, there are two types of anode active materials obtained through chemical conversion treatment: α-lead dioxide and β-lead dioxide.
It is known that the active material utilization rate is higher when the proportion of β-lead dioxide is higher.

According to the present invention, the aforementioned blend is used as the raw material. The anode plate produced by this method has a β-
The production rate of lead dioxide tends to be high. After the chemical conversion treatment is completed, a small amount of electricity is passed in the opposite direction to cover the surface with a thin layer of lead sulfate, a so-called retraction discharge. The specific gravity of sulfuric acid was adjusted from 1.26 to 1.
28, and use a charged lead-acid battery.

As already mentioned above, the assembly can be carried out before the chemical conversion or after the chemical conversion treatment.

For the container and lid, polypropylene, propylene-ethylene copolymer, acrylonitrile. styrene resin,
A resin made of acrylonitrile-styrene-butadiene resin or the like is used. As the separator, flat plates or ribbed wooden boards, phenolic resin-impregnated paper, microporous rubber, nonwoven fabrics made of synthetic resin fibers such as polypropylene and polyester, porous synthetic resin membranes, etc. are used, and these separators are preferably Can be used in combination with glass fiber mats. During assembly, the connections between each cell are made using the so-called COP (Connection On Over) depending on the type of battery case, etc.
thepartitiOn) method or CTP (
ConrlectiOnthrOugtlthepar
It can also be performed using the titiOn) method. The lead-acid battery according to the present invention has a significantly higher active material utilization rate than a conventional storage battery using lead monoxide as an active material raw material, since it uses the above-mentioned blend as an active material raw material. ing.

Thus, according to the present invention, compared to known lead-acid batteries,
It will be easily understood that the discharge capacity can be increased when compared with the same weight, and the weight of the battery can be reduced when compared with the same discharge capacity.

Furthermore, since the lead-acid battery of the present invention has excellent retention of utilization rate, it is easy to see that the lead-acid battery of the present invention has an outstanding service life.
Please understand. The present invention can also be easily applied to so-called clad batteries.

When manufacturing positive electrode plates for clad batteries, sagging lead is used. It is manufactured by placing a porous cylindrical body around a spine made of antimony alloy, filling the gap between the two with the above-mentioned blend, and performing a chemical conversion treatment. As the porous cylindrical body, porous resin or rubber tubes, glass tubes, porous fiber tubes, etc. are used, and these porous tubes are generally arranged horizontally in many rows. It can be used in any form. Porous resins or rubber tubes are made of polyolefins such as polyethylene, polypropylene, and EPR; vinyl chloride resins, vinylidene chloride resins, vinyl fluoride resins, polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymers, and chloropropylene. Halogen-containing polymers such as rubber; acrylonitrile/styrene copolymer, acrylonitrile/styrene/butadiene copolymer, NBR. ．． They can be made of acid-resistant resins such as copolymers such as SBR, and these tubes are used with multiple slits.

Porous fiber tubes include glass fiber, rock wool,
Inorganic fibers such as slag wool and asbestos fibers, various fibers such as polyethylene fibers, polypropylene fibers, vinyl chloride fibers, vinylidene chloride fibers, acrylic fibers, polyester fibers, aromatic polyamide fibers, polytetrafluoroethylene fibers, etc. , rectangular tubes, or tubes woven or knitted in the shape of horizontally connected tubes, or fabrics made of the aforementioned fiber felt, nonwoven fabric, etc., are used.

The inner diameter of these porous tubes is not particularly limited, but can generally range from 5 to 50 wt, particularly from 10 to 2 wt.

The blend can be filled into the void between the porous tube and the spine in a powder or wet state, and in this case, means known per se such as vibration, impact, pressure, ultrasonic irradiation, etc. can be used. .

The packing density of new lead monoxide is generally 2.5 to 6.0f.
1/Crll especially 2.6 to 4.0y/c! It is desirable to set the range to l. Even when manufacturing clad type electrode plates,
In order to improve various properties of the clad plate, any additives or compounding agents known per se can be added and blended into the blend according to known formulations. The chemical conversion treatment of the clad type positive electrode plate can be performed in the same manner as in the case of the paste type anode described above.

The present invention will be explained in more detail based on the following reference examples, comparative examples, and examples. Reference Example 1 A method for producing new ultrafine lead monoxide particles and its lead oxide will be explained.

The novel ultrafine particle lead monoxide was produced by a wet method in accordance with the method described in US Pat. No. 4,117,104, which was invented by the present inventors.

As the raw material metal lead, a metal lead ingot of fluorine, which is called electrolytic lead, was melted and formed into a spherical shape with a diameter of about 1 to 6 wL using the principle of melt fracture. As a device for producing lead oxide directly in water from these metallic lead particles, a stainless steel rotary mill using a wet grinding method described below was selected, and a method of continuous production using this rotary mill was adopted.

This rotary mill for continuous production is a stainless steel tube mill with an inner diameter of 34 mm. ? The main body of the mill is a pressure-resistant container with a length of 13 cm and an internal volume of about 120 e, which can withstand IOk9/d gauge pressure.A manhole of about 20 c1n square is installed in the center of this tube mill to allow cleaning of the inside and loading of raw materials. Naturally, manholes should be provided with covers, and 10k9
/Cl, to withstand gauge pressure. Furthermore, as an inlet for the liquid medium, a 112-inch stainless steel vibrator is connected to one end plate of the tube mill via a Rotsky joint, and a 3-horsepower diaphragm pump can be used to pressure inject the liquid medium into the tube mill. On the other hand, as an outlet for the reaction product slurry, a 1-2 inch stainless steel vibrator was attached to the tube mill end plate on the opposite side of the inlet via the Rotskie joint in the same way as the inlet, and was placed inside the tube mill. The tip of the vibrator is inserted so as to be inserted below the liquid level in the mill, and the reaction product slurry can be discharged from the discharge vibrator to the outside of the mill using the internal pressure inside the tube mill. At this time, in order to prevent the solid matter in the tube mill from entering the vibrator, a stainless wire mesh is provided at the tip of the discharge vibrator in the center of the mill from the tip of the vibrator. Furthermore, cooling water is poured outside the tube mill so that the entire tube mill can be cooled. In parallel with this, in order to effectively achieve a cooling effect in the reaction system, all or part of the reaction product slurry discharged from the tube mill, or the aqueous medium introduced into the tube mill, is used as cooling water or A refrigerator was used to cool it down to a predetermined temperature. Next, in order to rotate this tube mill, a 1-horsepower motor was used to drive the tube mill, which was interlocked with gears, and at the same time, a continuously variable transmission was used so that the rotation speed of the tube mill could be varied from 20 to 100 revolutions per minute. It was adjusted to

In addition, a liquid cyclone was attached to the tube mill and installed at the end of the discharge port of the tube mill to prevent unreacted substances from transferring into the product if they were mixed into the reaction product slurry. .

The conditions for producing wet-saw lead oxide directly from metal salt grains using this continuous wet-pulverization type tube mill are as follows. 200k9 of fresh metal lead grains with a diameter of ~6 mm are introduced through the manhole in the center of the tube mill, then water is selected as the liquid medium, and each liquid medium is shown in Table 1. If the temperature is low, the tube mill is actively cooled to a predetermined temperature. On the other hand, the tube mill is also maintained at a predetermined temperature by pouring water whose temperature has been adjusted to the desired predetermined temperature from the outside. First, water or acetic acid solution 30e maintained at a predetermined temperature is poured into the tube mill, and the solid-liquid ratio of the raw metal lead particles to the liquid medium is approximately 6. .6, then 11 in a tube mill.
injected into the cooled water or acetic acid solution at a rate of 1/min, and in parallel with this, adjust so that the same amount of separated liquid corresponding to the amount of liquid injected at the same time is discharged and collected from the tube mill,
The resulting dispersion containing lead oxide was continuously collected. In parallel, oxygen gas (02) was filled into the tube mill from an oxygen cylinder, and the internal pressure was adjusted to the internal pressure gauge pressure shown in Table 1, and the internal pressure was maintained at all times during the oxidation reaction. is caused by oxygen gas,
Manufacturing conditions were selected so that the internal pressure was maintained at a predetermined gauge pressure, and a continuous oxidation reaction was carried out. After the oxidation reaction has completed three times, the resulting dispersion containing lead oxide is collected, and the unreacted metallic lead contained in each is separated and removed using a liquid cyclone. Lead dispersion 3
Types (A-1, A-2 and A-3) were produced and recovered. At this time, the amount of dispersion liquid collected here and the P in the dispersion liquid are
The bO concentration was measured, and the amount of PbO produced was determined from this value.

The results are also shown in Table 1. Furthermore, each recovered dispersion liquid was separated into solid and liquid using a centrifuge, and each cake obtained was dried under reduced pressure at a low temperature of 50°C and reacted with three types of new ultrafine powder. Lead monoxides (A-1, A-2, and A-3) having high properties and excellent light resistance were produced. For each of the lead oxide powders obtained here, eight physical properties were tested and measured using the methods described below, and the above measurement results are also shown in Table 1. F test method: (
a) Amount of lead monoxide (PlO) produced (V/Hr) Collected in 3 oxidation reactions. Recovery amount of recovered dispersion liquid (ml) and lead monoxide (PbO) concentration of the dispersion liquid (y/100ml)
From the analysis and measurement results, the amount of PlO produced was determined as a y number from the direct absolute amount of lead monoxide produced by the oxidation reaction in the three powders, and was converted to the amount produced in 60 minutes and displayed. The quantitative analysis of lead monoxide was conducted in accordance with the method described in JIS K-1456, and by the method described below. (
b) Average particle size (number average): 1,000 to 3,000 to 1,000 to 3,000 by water paste method using a JEOL Co., Ltd. Spacecorp type (JEM-50) electron microscope. The size of 200 to 300 particles was measured at a magnification of 00@, and the average particle diameter (μ) was determined from the number average of the size of each particle.

(C) Fill a true density pycnometer with benzene solution and measure the weight (W) and temperature (Ti) with the provided thermometer.

Next, the benzene is discharged, and the sample is collected in a predetermined amount (M(y)
), add benzene, place in a vacuum desiccator, and turn the vacuum pump to 3T! The pressure was reduced to RmHy for 3 hours, the cock was closed, the vacuum pump was removed, and the temperature was brought to Ti and left overnight. Open the cock, take out the pycnometer, fill it with benzene, measure the weight (W'') and temperature (Ti), and calculate using the following formula (1).Cls
: Sample density d: Specific gravity of benzene in TiOC (d) Pour 500 ml of water into a beaker with a chromic acid reaction rate of 21, accurately weigh 69.06 y of lead oxide powder as a sample into the beaker, and slowly mix well. Pour into the water while stirring to make sure it is fully submerged. This dispersion is then heated to 65°C.

On the other hand, an aqueous solution of chromic anhydride (30.94y
/ 100 m 1 water) 100 t of water, slowly stirred for 3
The mixture is poured over a period of time, and further maintained at 65°C, stirred and aged for 6 times to form crystals of chromic acid and lead. Next, NO. The lead chromate crystals are filtered through No. 3 Fuchi paper, washed with water, and the resulting lead chromate is
After drying at 10°C, the amount of chromic acid fixed as lead chromate was quantitatively analyzed using the amount (y) of chromic acid anhydride (CrO3), and from this result, it was determined that the fixed chromic acid (CrO3)
Amount (y) AC and the raw material used lead chromate (CrO3
) amount (y) The chromic acid reaction rate (RC%) was determined from the following formula (2) from the ratio with TC.

(e) X-ray diffraction measurement X-ray self-recording diffractometer manufactured by Rigaku Denki Co., Ltd. (X-ray generator is CatNO.2OOl, goniometer is wide-angle Ca
tNO. 2227, Proportional Counter) and the samples were measured by the powder measurement method according to the diffraction conditions described below.

Diffraction conditions Target Cu Filter Ni Voltage 30KV Current 15n1A Count Range 1000CPS High voltage
1450V Time●Constant 1sec Chart●Speed 1c! n/Min scanning speed 1c/Min diffraction angle (2θ)
17/~60.5 Slit width 1 -17-0.
3. The abbreviations in the table represent lead monoxide: M: mashikoto type, L: litharge type, H: hydrated type.

f) Light resistance Sample 1y was taken on a glass plate of a Feeper type mala,
Vehicle (1y castor oil + DiOctylphthal
ate'' (DOP) 1g) was added and kneaded well with a mala to make it homogeneous. Transfer this to a glass plate, add 3.7y of colorless Lutzker Clear, and knead well. Mix to make a homogeneous paste.

Pour the prepared paste onto art paper, leaving a gap of 0.
Using a 2032-color film applicator, it is stretched to a uniform thickness on the art paper and air-dried at room temperature to form a hue sheet. This hue sheet was heated using a high-pressure mercury lamp for fading test (manufactured by Tokyo Shibaura Electric Co., Ltd. (H-400FT).
The mold was set 36 cm away from the mold, and irradiated with a two-ring mercury lamp while rotating at a rotation speed of 2 rpm.

The hue of the hue sheet that was irradiated with a mercury lamp and the hue sheet that was not irradiated with a mercury lamp obtained in this step was measured using a color difference meter (Model ND-101D, manufactured by Nippon Denshoku Co., Ltd.), and the hue was calculated using the following formula (3). ), ΔE (color difference) is determined and calculated using the method of ASTM D1482-5'TT.

LO, aO, civil: Hue before light irradiation L, a, b: Hue after light irradiation (g) Hiding power Based on the method described in JIS K5lO4-1964, first, the sample was prepared by the method described in the light resistance section. 5y and 3 ml of vehicle (castor oil 10I1 + DOPlOy) were thoroughly kneaded to prepare a paste in the form of an unchanging lacquer, and the hiding power of this paste was measured using a cryptometer, and the hiding power was calculated from the following formula 4. .

W; y number V of the sample; Cc number d of the oil used; specific gravity K of the sample; amount of change in the wedge thickness per 1 reading of the scale with the cryptometer constant L; the boundary line of the cryptometer becomes invisible. Distance (77!77 ri (h)) Composition analysis of lead oxide The composition was analyzed in accordance with the method described in JIS Kl 456 (Method for quantifying risarge).

In this specification, aqueous slurries are often used as target samples, but unless otherwise specified, all compositions are expressed in weight percent on a dry matter basis. (h-1) Lead monoxide (Pb
O) Accurately weigh the sample, measure the moisture content, and after converting the moisture content, (
If the sample was a powder, it was moistened with water beforehand.

) Add 6N acetic acid, heat, dissolve, and then cool.
Adjust the pH of the sample solution to 5.5 with aqueous ammonia and buffer.
0 to 5.5, titrate with a 11,100 molar EDTA (disodium ethylenediaminetetraacetic acid) solution using a xynol range as an indicator to determine the content (%) of lead monoxide (PlO). was determined on a dry matter basis. (h-2) Komyotan (Pb3O4) After sampling in the same manner as in the case of lead monoxide (h-1) above, the sample was dissolved in 6N acetic acid and sodium acetate, and then a certain amount of 111A Add a constant sodium thiosulfate solution, and after a certain time, back titrate with a constant iodine solution using the starch solution as an indicator.
The content (%) of Pb3O4) was determined on a dry matter basis.

(h-3) Metallic lead (Pb) After sampling in the same manner as in the case of lead monoxide (h-1) above, 6N acetic acid was added and dissolved by heating, and at the same time, 1M salt vinegar was added. Add a small amount of hydroxylamine to dissolve the lead peroxide compound present in the sample, then separate with Oki paper, wash with warm water, and wash until no lead components are detected in the washing solution. Transfer the residue on the paper to an Erlenmeyer flask, dissolve the metal lead on the paper with 6N nitric acid and 2 to 3 drops of 30% hydrogen peroxide, and then adjust the pH to 5 using aqueous ammonia and sodium acetate. The content (%) of metallic lead (Pb) was determined on a dry matter basis by titration with a 11,100 molar EDTN solution using a xylenol range as an indicator.

(h-4) Impurities (Fe, Cu) After sampling in the same manner as in the case of lead monoxide in (1) above, sample preparation was obtained by adding nitric acid and hydrogen peroxide to dissolve and repeating evaporation to dryness. The liquid was analyzed in accordance with the JIS KOL2O Atomic Absorption Spectrometry Method General Rules for Fe (iron) and Cu (
Copper) was quantified and its content (%) was determined on a dry matter basis.

In addition, Mashikotsu type lead monoxide (sample A-1), risarge type lead monoxide (sample A-2), and hydrated lead monoxide (sample A-
The IR absorption spectra of 3) are shown in FIGS. 4, 5, and 6, respectively.

Reference Example 2 In this reference example, another method for producing lead monoxide by a wet method using zinc oxide powder (lead powder) as a raw material and the lead monoxide will be described.

This manufacturing method and lead oxide are described in the patent application (Japanese Patent Application No. 135909/1989) which is an invention of the present inventors.
) According to the method described in the specification. As the lead zinc oxide powder used as a raw material, a dark gray-green lead zinc oxide powder manufactured by the Shimadzu lead powder method was selected.

The Shimadzu lead powder method employs a method of producing lead powder by dry-pulverizing pre-shaped metal lead particles from the same electrolytic lead as selected in Reference Example 1 in a rotary mill. Lead zinc oxide powder was recovered.

When the zinc oxide powder recovered in this step is analyzed and measured according to the method for measuring metallic lead components described below, the recovered lead zinc oxide powder has a metallic component of 31. It contains iron (Fe2O3) which is an impurity by -5ppm1 copper (CuO
), and the degree of the powder was 0.72 mt/y.

In addition, when measuring the "゜height" of the powder, the reciprocal of the value measured by the bulk specific gravity measurement method described later was taken and expressed in ml/y.This lead zinc oxide powder was mixed with water before entering the oxidation process. Prepare an aqueous slurry.

The concentration of zinc oxide component in the aqueous slurry at this time is 20y.
/100ml concentration. Next, a liquid cyclone that applies centrifugal force classification is used to classify and separate the coarse metallic lead powder contained in the raw material lead zinc oxide powder and the coarse particulate lead zinc oxide powder, and a homogeneous lead zinc oxide powder is separated. An aqueous slurry was prepared.

The liquid cyclone used for this) was a stainless steel liquid cyclone with a diameter of 55 φ, a conical apex angle of 20, an inlet of 8 ws φ, a downstream nozzle of 6 φ, and a discharge pressure of 1.8 kg/Ai.

The composition of the aqueous slurry of homogeneous lead zinc oxide whose coarse particles have been classified and separated using this liquid cyclone is 12.4 f1/100 nt as a solid content, and the amount of metallic lead in this solid content is was 10.5% by weight.

A contact method mainly using an aeration method was used to bring the homogenized aqueous slurry of lead zinc oxide into contact with molecular oxygen.

A specific device for this contact method mainly based on the aeration method is 2m in height and 0.6WL in diameter. A pliers-scale device with a single-fluid nozzle installed on the top of a stainless steel tower with a φ round shape is used, and an aqueous slurry of lead oxide is sprayed into the tower through the nozzle, and the oxygen in the air and The aqueous slurry oxidized by the spraying was recovered from the conical part provided at the bottom of the tower through efficient contact.

Then, in order to increase the oxidation efficiency of the aqueous slurry in contact with oxygen by this atomization, a height 17n1 diameter 0.6 was installed after the lower conical part of the contact tower with the above aeration method.
A bubble column equipped with an atomizer was attached to the tank made of stainless steel with dimensions of m and φ, and the air was sufficiently finely dispersed from the bottom of the tank into the liquid in the tank by bubbling.

After introducing the aqueous slurry recovered from the contact tower into this bubble column and filling it, air is finely dispersed in the aqueous slurry using an atomizer installed inside the bubble column, and the above aeration ensures sufficient contact with oxygen. Sufficient time was gained for the oxidation reaction of the aqueous slurry containing oxygen to be completed, and effective oxidation was completed. In addition, after the aeration type contact tower attached to this bubble column, a liquid cyclone similar to that used in preparing the homogeneous aqueous lead zinc oxide slurry described above was attached for separating and classifying unreacted zinc oxide components. Ta.

This liquid cyclone was used to classify and separate the unoxidized lead zinc oxide component remaining in the aqueous slurry after the oxidation step. The manufacturing conditions in the above manufacturing process were carried out under the two types of conditions shown in Table 2, and the lead monoxide dispersion 2
types (sample numbers B-1 and B-2) were collected.

In addition, the amount of lead monoxide recovered in this step is expressed as the metallic lead content (P
b) Calculate the lead component present in the aqueous slurry of zinc oxide powder added to the oxidation process in terms of lead monoxide recovery rate (%) in terms of metallic lead content (Pb), and show the results in Table 2. Also displayed.

Next, regarding the lead monoxide slurry recovered here, the average particle size, metallic lead components of lead oxide, etc. Various physical properties were measured for composition, chromic acid reaction rate, X-ray diffraction hue, and light resistance, and the results are also shown in Table 3.

Reference Example 3 In this reference example, conductive lead oxides prepared by various manufacturing methods will be described.

3-A: Conductive lead oxide was prepared by a wet method.

That is, the Huowanine metal lead ingot selected in Reference Example 1 was melted, and spherical metal lead particles with a diameter of about 1 to 6 m, which were molded using the principle of melt flak chiar, were placed in a rotary mill together with water as an aqueous medium. Using the wet grinding method, oxygen in the air is used to partially oxidize and scrape off the metallic lead component containing the lead oxide part, resulting in dark green-black lead powder (sample number S-). 1) was prepared.

The physical properties of the conductive lead oxide prepared here were measured, and the results are also shown in Table 4.

3-B: Conductive lead oxide was prepared from litharge.

That is, tartaric acid ((CHOHCOO
H) Add 2) and heat at about 70 to 80°C while stirring,
After converting to coarse or surge, the mother liquor is separated, and after drying,
A conductive lead oxide (sample number S-2) was prepared by irradiating the resulting surge powder with ultraviolet rays to form a low-order lead oxide with a dark gray surface on the surface of the surge particles.

The physical properties of the lead oxide prepared here were also measured,
The results are also shown in Table 4. In addition, the volume resistivity values (RVΩ-Cm) of Surge (PlO) (sample numbers A-1, A-2 and A-3) prepared in Reference Example 1 were 1 x 1011 for all three types. .

In addition, the particle diameter, volume resistivity (electroconductivity), and metal lead component in the table were measured by the following methods.

Measurement of particle diameter Particle diameter was determined using an electron microscope according to the measurement method described in the above-mentioned section (b) Average particle diameter.

Measurement of volume resistivity A powder sample of 0.2 y was taken on a powder electrode (manufactured by Ando Electric Co., Ltd., model SE-31) having an electrode area of 2.26 cr.
After applying a pressure treatment of 15k9/CIL between the electric J electrodes and pressing the sample to a thickness of 0.05TWL, a DC voltage of 16 volts (V) was applied between the electrodes, and then a minimum scale of 111000 (MA ) The interelectrode current (A) was measured using a luvanometer, and the volume resistivity (Rv) (ΩCrfL) was calculated from the following formula.

Rv = Conductivity is expressed as volume resistivity (Rv) value;
Therefore, the smaller the Rv (Rcwl) value, the better the conductivity. Measurement of composite lead components Quantitative determination was performed according to the method for measuring metallic lead (h-3) in the section (5) Compositional analysis of lead oxide described above.

Reference Example 4 In order to clearly explain the present invention, lead oxide produced by a dry method, which has been conventionally known as an active material for lead-acid batteries, will be explained.

Preparation of zinc oxide Lead zinc oxide was prepared using the Shimadzu lead powder method.

That is, the Huowanine metal lead ingot selected in Reference Example 1 was melted, and a diameter of 2.5 cTn x length of 2.0 C7r was obtained.
After molding it into a cylindrical shape of T, it is made according to the method described in Genzo Shimazu's research report, Journal of the Japan Society of Mechanical Engineers, Vol. 28 (NO.1OO), pp. 489-516 (1925) 1f-).
In a rotary mill, the surface of the metal lead grains is oxidized with air using a dry grinding method, and the oxidized parts are mainly crushed and peeled off by the lead grains hitting each other to form a dark gray-green suboxide. Lead powder (so-called lead powder) was prepared.

(a) Mashikotsuto type resurgery The lead zinc oxide powder produced as described above was
It was produced by firing at 600 to 650°C and then pulverizing according to the method described in Japanese Patent No. 01.

Mashikotsuto type surge powder (Mizusawa Chemical Industry Co., Ltd.) (sample number H-1) having the composition and physical properties shown in Table 5 was selected. ]) Commercially available reagent Resurge Ni As another adhesive, Resurge (H-2), a commercially available reagent Resurge powder (manufactured by Koso Kagaku Co., Ltd.) having the composition and physical properties shown in Table 5, was selected.

Circle Example 11 Method for preparing paste-type positive electrode plate 1 The above-mentioned Reference Examples 1 and 2 were used as the active material raw material for the electrode plate.
The novel wet method lead monoxide prepared in Example 3 and the conductive lead oxide prepared in Reference Example 3 are mixed in advance by the method described below, or selected individually without mixing, and the active material raw material powder 1 is prepared.
09 thickness 57rf:! Take it on a glass plate of n, and add 1 m of water.
1 and D2O = 0.9 m of sulfuric acid with specific gravity of 1.223
1 and knead thoroughly with a mesh spatula until the hardness is suitable for kneading into a lattice shape to prepare a paste of active material raw material containing 1% lead sulfate by dry weight. Next, add the above active material raw material paste. 1.8cm x 4.2α x 0.2C77
! Filled with a grid of lead-antimony alloy, sandwiched between two rubber plates, and using a hydraulic press, approximately 35k9/C
A pressure of 1 t was applied for 1 minute, and then dried at 100° C. for about 1 hour to prepare an electrode plate filled with the active material.

2 The dry electrode plate was treated with 200 mt of sulfuric acid with D2O=1.223.
A lead plate having an area approximately three times that of the positive electrode plate was used as a counter electrode, and the circuit shown in FIG. 1 was assembled to perform pretreatment for a discharge test.

■ Pretreatment method 1 In Figure 1, the container body E has a thickness of 8
Assembled from transparent PVC with a polypropylene diaphragm D in the middle.
was sandwiched to prevent the products from both the left and right chambers from mixing.

As a reference electrode, a mercurous sulfate electrode (Hg/Hg2SO4) in sulfuric acid with D2O=1.223 was used. D2O=
The potential for hydrogen electrode in sulfuric acid of 1.223 is 605
It was mV. A potentiostat (manufactured by Hokuto Denko Co., Ltd.) was used as the charging/discharging device.

2 Set the electrode plate B prepared by the operation described in I in the position B in Figure 1, set the charging/discharging device P so that the current flows from the test electrode plate B to the counter electrode plate B'', and check the current density. So 5
50% of the amount of electricity required to change the lead oxide active material filled in test electrode plate B into lead dioxide (PbO2) at a constant current of 0n1A/d (hereinafter in this specification, this electricity The amount of electricity is called the theoretical chemical charge).

After applying a predetermined amount of electricity, the test electrode plate B is brought into an open circuit state and the potential of the test electrode plate B is stabilized.

(1.10■ for the reference electrode) 3 Set the charging/discharging device P in the opposite direction to 2 so that the current flows from the return electrode plate B'' to the test electrode plate B, and set the discharge current density 661T1A/Clt. The electric potential of the electrode plate B is 800rT1V with respect to the reference electrode.
Discharge to an open circuit state and stabilize the potential.

4. The charging/discharging device P is set in the same manner as in 2, and electricity is applied at a constant current density of 50 rT1A/d with an amount of electricity equal to 50% of the theoretical chemical formation electricity amount of the active material raw material and the previous discharge amount.

After passing a predetermined amount of electricity, the circuit is brought into an open circuit state and the potential is stabilized. Steps 53 and 4 are repeated three more times to complete the preprocessing.

■ Discharge test and utilization rate 1 The test electrode plate B that has undergone the pretreatment described above is set in the circuit shown in Figure 1, the charging/discharging device P is set as a discharge circuit, and the current density is 66.
m1A/Cl. At a constant current of , the potential of electrode B was discharged to 800 rT1V with respect to the reference electrode, and the utilization rate Ru (%) was determined from the following (7).

In the formula, W is the active material weight (V) of positive electrode B, and AH is the positive electrode (B
) discharge capacity (ampere hour -, product of discharge current and discharge time), K is the coefficient 0.224 ampere hour/
It is y.

Note that W is the active material, lead oxide paste, which has been completely converted to lead dioxide (PbO2) through the pretreatment process.
Calculated from the amount of lead oxide filled in the test electrode plate.

2 After the discharge, keep the circuit in an open circuit state and when the positive electrode B stabilizes, add 50% of the theoretical chemical formation electricity amount described in the pretreatment operation in section ① and the discharge electricity amount of 1 to a current density of 501T1A/
Charging was performed using a C7li constant current.

31. The operation of 2 was repeated to measure the utilization rate.

As active material raw materials, the new wet method lead monoxide and conductive lead oxide are mixed thoroughly and homogeneously in powder form in advance according to the type (indicated with sample number) and amount ratio shown in Table 6. After that, a test electrode plate was prepared according to the method described in Section I above. As a comparative example, Reference Example 4
A test electrode plate was prepared in the same manner as above when the known dry method lead oxide described in 1. was selected as the active material.

After performing the pretreatment on each test electrode plate prepared above, the utilization rate was determined, and the results are also shown in Table 6.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of the charge/discharge test device used in the examples, Figure 2 is the IR absorption spectrum of known yellow orthorhombic PbO(7), and Figure 3 is the IR absorption spectrum of known red tetragonal PbO. (7)I
R absorption spectrum, FIG. 4 is the IR absorption spectrum of the mashikotsuto type lead monoxide (Reference Example 1, sample number A-1) used in the present invention, and FIG. 5 is the IR absorption spectrum of the surge type lead monoxide used in the present invention. The IR absorption spectrum of lead (Reference Example 1, Sample No. A-2), Figure 6 shows the hydrated lead monoxide used in the present invention (
The IR absorption spectrum of Reference Example 1, sample number A-3) is shown. Reference symbol A is an ammeter, B is a test electrode, B'' is a counter electrode, C is a reference electrode, D is a diaphragm, E is a battery container, P is a charging/discharging device, V
represent potentiometers, respectively.

Claims (1)

[Claims] 1. In a lead-acid battery comprising lead oxide or a chemically converted product of its sulfuric acid paste as an electrode active material, the lead oxide is
(A) True density of 8.3 to 9.2 g/cc, primary particle size of 0.2 microns or less, wave number 1400 to 1410 cm
^-^1 Lead monoxide having an infrared absorption peak and a chromic acid anhydride reaction rate of 94% or more or its heat treatment and (B
) 1 to 50% by weight per lead monoxide with the formula PbO_x, where x is a number from 0.1 to 0.9, and a volume of 1 x 10^6 to 5 x 10^1^0 Ω-cm. A conductive lead acid having a lead shell type, which has a specific resistance and whose interior is made of lead monoxide or lead oxide with a relatively high degree of oxidation, and whose surface part is made of metallic lead or lead oxide with a low degree of oxidation. A lead-acid battery characterized by being composed of a mixture with a chemical compound. 2. The lead-acid battery according to claim 1, which contains 3 to 40% by weight of conductive lead oxide based on the lead monoxide (A). 3 The conductive lead oxide is 1×10^7 to 5×10^
A lead-acid battery according to claim 1, which is a lead oxide having a volume resistivity in the range of 9 Ω-cm. 4. The lead-acid battery according to claim 1, wherein the lead-acid battery includes a paste-type electrode plate containing as an active material a material obtained by chemical conversion treatment of the sulfuric acid paste of the mixture. 5. The lead-acid battery according to claim 1, wherein the lead-acid battery is equipped with a clad plate containing a material obtained by chemical conversion treatment of the mixture as an active material. 6. A method for manufacturing a lead-acid battery comprising filling a grid with a paste of lead oxide and sulfuric acid, and then converting the paste into an active material by chemical conversion treatment to form an electrode plate.
A) True density of 8.3 to 9.2 g/cc, primary particle size less than 0.2 microns, wave number 1400 to 1410 cm^
- lead monoxide or its heat-treated product having an infrared absorption peak at ^1 and a chromic acid anhydride reaction rate of 94% or more;
) 1 to 50% by weight per lead monoxide with the formula PbO_x, where x is a number from 0.1 to 0.9, and a volume of 1 x 10^6 to 5 x 10^1^0 Ω-cm. A conductive lead acid having a lead shell type, which has a specific resistance and whose interior is made of lead monoxide or lead oxide with a relatively high degree of oxidation, and whose surface part is made of metallic lead or lead oxide with a low degree of oxidation. 1. A method for producing a lead-acid battery, which comprises kneading a mixture with a compound and sulfuric acid to form a paste. 7 Filling the void between the core metal and the porous cylindrical body with lead oxide, and then subjecting it to chemical conversion treatment to convert the lead oxide into an active material,
In a method for manufacturing a clad lead-acid battery comprising forming an anode plate, (A) a true density of 8.3 to 9.2 g/cc, a primary particle size of 0.2 microns or less, and a wave number of 1400 to 1410 cm^-^ 1) lead monoxide or a heat-treated product thereof having an infrared absorption peak and a chromic acid anhydride reaction rate of 94% or more; and (B) 1 to 50% by weight based on the lead monoxide.
The formula PbO_x, where x is a number from 0.1 to 0.9, has a composition of Filling the void with a mixture of lead shell-type conductive lead oxide made of lead or lead oxide with a relatively high oxidation degree and whose surface portion is made of metallic lead or lead oxide with a low oxidation degree, A method for producing a clad lead-acid battery, which is then subjected to chemical conversion treatment.