JPH06176761A - Plate for lead-acid battery - Google Patents

Abstract

PURPOSE:To provide a plate of high electric discharging capacity, long life, and of low cost by using either/both of a specific porous wood powder or/and porous carbonized wood powder as a liquid retaining material to be contained in an active material at a specific weight percent. CONSTITUTION:Wood powder or carbonized wood powder, in which a plurality of tentative conduits 10 extend in the longitudinal direction, is used as a liquid retaining material at a size of 16-100mesh. This is added to an active material at 0.2-1.0wt.%, which is used as a plate for lead-acid battery. These are easily obtained compared with other liquid retaining materials such as water absorbing high polymer, silica, graphite, glass fiber and the like, and the manufacturing cost of the plate can thus be reduced. Diffusion to the active material is improved at the time of electric discharging of high efficiency by means of an electrolyte in a porous part, and the capacity of the battery and the utilization factor of the active material can thus be improved. The strength of an active material layer is increased for homogeneous diffusion to the entire part of the active materials, and the life characteristic of the battery can thus be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead storage battery electrode plate, and more particularly to a lead storage battery electrode plate in which a liquid-retaining substance is added to an active material.

[0002]

2. Description of the Related Art The capacity and the active material utilization rate of a lead storage battery can be increased by increasing the amount of electrolyte contained in the active material of the electrode plate. In particular, when the amount of the electrolytic solution contained in the positive electrode active material is increased, the capacity of the battery during high rate discharge can be greatly increased. Therefore, water-absorbing polymers, silica, graphite (carbon),
It has been proposed to increase the amount of electrolyte contained in the active material by adding a liquid-retaining substance such as glass fiber.

[0003]

However, when a water-absorbing polymer, silica, graphite or the like is used as the liquid-retaining substance, the liquid-retaining substance is expensive and the manufacturing cost of the electrode plate is high. There's a problem. Further, since these liquid-retaining substances are difficult to bond with the active material, there is a problem that when added to the active material, the strength of the active material of the electrode plate is lowered and the life of the battery is shortened.

An object of the present invention is to provide a low-cost lead-acid battery electrode plate in which the porosity of the active material can be increased to increase the discharge capacity of the battery and the strength of the active material layer can be increased. It is in.

[0005]

According to the invention of claim 1, a lead-acid battery electrode plate in which a liquid-retaining substance is added to an active material is used, and a dried porous wood powder as the liquid-retaining substance and At least one of porous carbonized wood flour is used.

Incidentally, the "dry porous wood powder" referred to here
Is wood flour made by evaporating water to make it porous, and such wood flour has a plurality of pores extending in the fiber direction. Further, "carbonized wood powder" means wood powder that is at least partially carbonized.

According to a second aspect of the invention, in the first aspect of the invention, wood flour and carbonized wood flour having a size of 16 mesh to 100 mesh are used.

According to the invention of claim 3, in the invention of claim 1, the weight ratio of the liquid-retaining substance to the total weight of the lead oxide powder used for forming the active material layer is less than 3%.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the slender wood flour and carbonized wood flour in which a plurality of temporary conduits extend in the longitudinal direction are used as the liquid retaining material.

[0010] The term "tracheal tube" as used herein refers to a cell of a wood portion having an edged wall hole extending in the axial direction among cells of wood, and is called a fiber for convenience. When the wood powder is sufficiently dried, a plurality of through holes extending in the fiber direction are formed inside, and the wood powder has a so-called honeycomb structure.

According to the invention of claim 5, in the invention of claim 4, the weight ratio of the liquid retaining material to the active material is 0.2% or more and 1.0% or less.

According to the invention of claim 6, in the invention of claim 4 or 5, the area of the end faces in the longitudinal direction of the wood powder and the carbonized wood powder is 0.04 mm ² or more.

[0013]

[Function] Wood flour and carbonized wood flour (hereinafter referred to as wood flour, etc.)
It can be easily obtained compared to liquid-retaining substances such as water-absorbing polymers, silica, graphite, and glass fibers. Therefore, when dry porous wood powder or the like is used as the liquid retaining material as in the invention of claim 1, the manufacturing cost of the electrode plate can be reduced. Further, since the electrolytic solution can be stored in the porous portion such as wood powder, the diffusion of the electrolytic solution into the active material at the time of high-rate discharge is improved, and the capacity of the battery and the utilization rate of the active material can be increased. Moreover, since wood powder and the like are dispersed throughout the active material, the active material reacts uniformly with the electrolytic solution in the thickness direction of the electrode plate, and the stress load due to the local reaction of the active material does not increase and the battery life becomes longer. The characteristics can be improved. In addition, since the active material penetrates into the porous part such as wood powder, the binding force between the active material and the liquid-retaining material is higher than that of the conventionally used liquid-retaining material, which improves the life characteristics of the battery. You can Further, since the porous carbonized wood powder has high conductivity, when the carbonized wood powder is used as the liquid-retaining substance, the content can be appropriately selected to increase the conductivity in the active material. There is.

When wood powder having a size of 16 mesh to 100 mesh is used as in the second aspect of the invention, the discharge capacity of the battery can be increased in a preferable range. When the size of wood powder or the like becomes smaller than 100 mesh, the discharge capacity of the battery cannot be increased so much because the content of the electrolytic solution such as wood powder or the like decreases. Further, when the size of wood powder or the like becomes larger than 16 mesh, the content of the electrolyte solution such as wood powder or the like increases, but the volume increases, so that the active material filling amount decreases and the discharge capacity of the battery cannot be increased. .

When the weight ratio of the liquid-retaining substance to the total weight of the lead powder used for forming the active material layer is less than 3%, the discharge capacity of the battery can be greatly improved. Contribute. However, when the weight ratio of the liquid-retaining substance is 3% or more, the amount of the active material filled decreases, and conversely the discharge capacity of the battery decreases.

[0016] When a long and thin wood powder having a plurality of temporary conduits extending in the longitudinal direction is used as in the fourth aspect of the invention, the electrolytic solution moves in the temporary conduit, so that the electrolytic solution is generated in the active material. Move smoothly. Since the discharge capacity of a battery is governed by the movement of sulfate ions and hydrogen ions, when the movement of the electrolyte solution in the active material becomes smooth, the discharge reaction proceeds almost uniformly over the entire electrode plate, and the active material is used. The rate is greatly improved. Therefore, the capacity per unit weight of the active material becomes high. Further, the shape of the end face portion where the temporary duct is exposed has a complicated shape like a honeycomb structure, and the surface area of the end face portion is extremely larger than that of a general reinforcing material such as a solid cut fiber. Therefore, the active material enters the entrance portion of the porous portion such as wood powder, and the binding force between the active material and the liquid-retaining material is significantly increased. Moreover, since the plurality of temporary conduits extend in the longitudinal direction, the bending strength of the wood powder or the like becomes high, and the slender wood powder or the like functions as a reinforcing material for the active material layer to prevent the active material from falling off.

When the weight ratio of the elongated wood powder or the like to the active material is 0.2% or more and 1.0% or less, the utilization rate of the active material is increased. The weight ratio of wood powder is 0.
When it is less than 2%, the wood powder does not act sufficiently as a liquid retaining substance, and when the weight ratio of the wood powder exceeds 1.0%, the filling amount of the active material decreases and the utilization rate of the active material decreases. To do.

When the area of the end face in the longitudinal direction of the slender wood powder or the like is set to 0.04 mm ² or more as in the invention of claim 6, the utilization factor of the active material becomes high. If the area is less than 0.04 mm ² , the number of temporary pipes in the wood powder or the like decreases, and the electrolyte cannot be moved sufficiently, so that the utilization rate of the active material decreases.

[0019]

EXAMPLES Examples of the present invention will be described in detail below with reference to an anode plate for a lead storage battery.

[Example 1] The positive electrode plate for a lead storage battery of this example was manufactured as follows. First, a Japanese cedar tree, which is a coniferous tree, was cut into a size of 16 mesh to 100 mesh using an automatic pulverizer, and then dried at 40 ° C. for 24 hours to produce wood flour. In this example, the wood powder was cut without specifying the cutting direction. FIG. 1 is an enlarged view of a plane orthogonal to the fiber direction of the wood powder thus produced or the direction in which the temporary conduit extends. In FIG. 1, the black portion is the hole portion 1, and the fiber forming this hole portion is the temporary conduit. These holes 1
Thus, a large number of holes extending in the fiber direction are formed in the dried wood flour. Next, lead oxide powder, wood powder of less than 3% by weight with respect to the lead powder, and dilute sulfuric acid were kneaded to prepare an active material paste. Then, this active material paste was filled in a current collector made of a cast grid, and then this was aged, dried, and formed to complete an anode plate for a lead storage battery.

Next, the anode plate a of this embodiment and the conventional anode plate b
The relationship between the added amount of the liquid-retaining substance and the capacity of the battery was investigated by using the batteries prepared by combining and with the same cathode plate. ◎ Anode plate a is the anode plate of this embodiment made by using wood powder having a size of 24 mesh to 32 mesh, and anode plate b is 20-30 μm silica instead of wood powder as a liquid-retaining substance. It is a conventional anode plate made by adding it to an active material paste. Incidentally, the cathode plate is a known cathode plate in which a liquid retaining substance is not added to the active material, and the anode plates a and b have the same structure except for the liquid retaining substance. Then, nine different anode plates a and b each having a weight ratio of the liquid-retaining substance to the lead powder in the range of 0% to 5% are made, and one of the anode plates a is used as a cathode via a retainer holding an electrolytic solution. An electrode plate group was formed by laminating one plate, and the entire electrode plate group was wrapped with a resin film to form nine types of lead storage batteries A and B, respectively. Then, each battery was discharged at a high rate of 3 A and the discharge time was measured. FIG. 2 shows the measurement result. As shown in the figure, in the anode plate a of this example using wood powder as the liquid-retaining substance, the discharge capacity at high rate discharge of the battery as a whole is higher than that of the conventional anode plate b using silica as the liquid-retaining substance. It can be seen that it can be increased by about 35%. The cause of this increase in capacity is that, unlike silica, wood flour has a size several hundred times larger than the particle size of lead powder. It is possible to prevent the material from peeling or falling off, to allow the electrolytic solution to be pooled in the porous part so that the electrolytic solution can smoothly diffuse in the active material due to discharge, and the porous part of the wood powder can cause stress in the active material due to charging and discharging. It is possible to absorb Also,
From this figure, it can be seen that the discharge capacity of the battery decreases when the weight ratio of wood powder to the total weight of lead powder used to form the active material layer exceeds 3%.

Next, the relationship between the size of wood flour and the capacity of the battery was investigated. First, using an active material paste containing wood flour of each size in the range of 10 to 200 mesh, 8
I made different kinds of anode plates. The weight ratio of wood powder to the total weight of lead powder in each electrode plate was 0.5%, and each electrode plate had the same structure as the electrode plate of this example except for the size of the wood powder. There is. Next, one anode plate is laminated with one cathode plate through a retainer that holds an electrolyte to form an electrode group, and the entire electrode group is wrapped with a resin film to form eight types of lead-acid batteries. Had made. Then, each battery was discharged at a high rate of 3 A and the discharge time was measured. FIG. 3 shows the measurement result. From this figure, it can be seen that the capacity of the battery decreases as the size of the wood powder becomes smaller so that it passes through a 100-mesh sieve or becomes too large to pass through a 16-mesh sieve.

Next, the batteries A and B used in the test shown in FIG. 2 were discharged to a final voltage of 1.74 V at 3 A and allowed to rest for 0.5 hour, and then charged at 1.6 A for 3.5 hours (limit voltage 2 .4
Charging / discharging at 7 V / cell was repeated to examine the life characteristics of the batteries A and B. The weight ratio of the liquid retaining material to the lead oxide powder in each of the batteries A and B was 0.5%. FIG. 4 shows the measurement result. From this figure, it is understood that the battery A using the anode plate a of this example has almost the same cycle characteristics as the battery B using the conventional anode plate b using silica as the liquid retaining material.

[Example 2] The positive electrode plate for a lead storage battery of this example was manufactured as follows. First of all, a sugi tree is carved to a thickness of 0.25 mm along the fiber direction of the tree, and the width dimension (dimension in the direction orthogonal to the fiber direction) is 0.25 mm and the length (dimension in the fiber direction) is 1.0 mm. After cutting, it was dried at 40 ° C. for 24 hours to make elongated wood flour. FIG. 5 is a schematic perspective view of the wood flour thus produced. As shown in the figure, the wood powder has a plurality of temporary conduits 10 ...
, And the cross-sectional structure of wood flour has a so-called honeycomb structure. Next, an active material paste was prepared by kneading the lead oxide powder, the wood powder and the dilute sulfuric acid in an amount such that the weight ratio to the active material after chemical formation was less than 1.5%. Then, this active material paste was filled in a current collector made of a cast grid, and then this was aged, dried, and formed to complete an anode plate for a lead storage battery.

Next, in order to examine the characteristics of the anode plate of this example, five anode plates c to g were prepared and tested. The anode plate c is the anode plate of this embodiment, which is made by using wood powder having a size of 24 mesh such that the weight ratio to the active material is 0.4% after chemical conversion. The anode plate d is the anode plate of the comparative example made by using wood powder having a size of 32 mesh in which the direction in which the temporary tube extends is not specified as in Example 1. The amount of wood powder added to the anode plate d is the same as that of the anode plate c. The anode plate e is 0.1% by weight of the active material of the anode plate d.
This is an anode plate of a comparative example in which the cut fiber (reinforcing material) [diameter of about 10 μm, average length of 500 μm] was added. The anode plate f has a weight ratio to the active material of 0.4 after chemical conversion.
It is a conventional anode plate made of an active material to which is added graphite (a liquid retaining material) having an average particle size of 50 μm and a cut fiber of 0.1% by weight. The anode plate g has only the above-mentioned cut fiber of 0.
It is a conventional anode plate made using an active material added with 1% by weight. The anode plates c to g have the same structure except for the additives. Then, the anode plates c to g were dropped onto the iron plate 5 times from the position of 70 cm in height, the amount of the active material dropped was measured, and the active material strength of each anode plate was measured. FIG. 6 shows the measurement result. It can be seen from this figure that the positive electrode plate c of this embodiment has a small amount of active material falling off. This is about one-fifth the amount of fall of the conventional anode plate f using graphite as the liquid-retaining substance, and about 1/2 of the drop of the conventional anode plate g containing only cut fibers (reinforcing material). Is the amount.

Next, each one of the anode plates c to g is laminated with one known cathode plate in which a liquid-retaining substance is not added to the active material through a retainer holding an electrolytic solution, to laminate a plate group. Then, the whole of the electrode plate group was wrapped with a resin film to produce lead acid batteries C to G. Then, each of the batteries C to G was discharged at a high constant current of 1 CA, and the utilization rate of the anode active material of each battery was examined. FIG. 7 shows the measurement result. From this figure, it can be seen that by using the anode plate c of this example, the utilization rate of the anode active material can be increased to 30% or more despite the high rate discharge.

Next, each battery C to G was discharged at 3A to a voltage of 1.74V from beginning to end and then charged and discharged at 1.6A for 3.5 hours (limit voltage of 2.47V / cell). The life characteristics were investigated. FIG. 8 shows the measurement result. From the figure, it is 500 if the anode plate c of this embodiment is used.
It can be seen that a battery with a life exceeding the cycle can be obtained.

Next, the relationship between the weight ratio of the wood powder to the active material and the utilization rate of the anode active material was investigated. FIG. 9 is a diagram showing the utilization rate of the anode active material of each electrode plate prepared by changing only the weight ratio of wood powder to the active material in the anode plate c of this example. From this figure, it can be seen that the utilization ratio of the anode active material increases when the weight ratio of wood powder is 0.2% by weight or more and 1.0% by weight or less. When the weight ratio of wood powder is less than 0.2% by weight, the action of the wood powder as a liquid-retaining substance decreases, and when the weight ratio of wood powder exceeds 1.0% by weight, the amount of the active material filled decreases. As a result, the active material utilization rate decreases.

Next, the relationship between the area of the end face of the wood powder in the longitudinal direction and the utilization rate of the anode active material was examined. FIG. 10 is a diagram showing the utilization rate of the anode active material of each electrode plate prepared by changing only the area of the end face in the longitudinal direction of the wood powder in the anode plate c of this example. From this figure, the area of the end face of wood flour in the longitudinal direction is 0.04.
It can be seen that if it is less than mm ² , the utilization rate of the anode active material decreases. This is because when the area is less than 0.04 mm ² , the number of temporary pipes in the wood powder decreases and the electrolyte cannot be moved sufficiently.

[Example 3] The positive electrode plate for a lead storage battery of this example was manufactured as follows. First, after cutting a Japanese cedar tree, which is a coniferous tree, with an automatic crusher into a size of 10 mesh to 100 mesh without specifying a cutting direction, a gas burner is used to reduce contact with oxygen as much as possible at 500 ° C. for 1 hour. The average degree of carbonization is 80%
A carbonized wood powder having a size of 32 mesh to 42 mesh was prepared by. The steaming temperature and time may be determined in consideration of the degree of carbonization to be obtained and the strength of the carbonized wood powder. In the case of cedar wood powder, the temperature and time range from 200 to 500 ° C. By steaming for 1 to 2 hours, it is possible to obtain an appropriately carbonized wood powder. Next, an active material paste was prepared by kneading lead powder containing lead oxide, carbonized wood powder of 0.5% by weight with respect to the lead powder, and dilute sulfuric acid. The amount of carbonized wood powder added is preferably in a range that does not significantly reduce the amount of the active material filled, and in the present embodiment, it is preferably added in the range of less than 3% by weight with respect to the lead powder. Then, this active material paste was filled in a current collector made of a cast grid, and then this was aged, dried, and formed to complete an anode plate for a lead storage battery.

Next, in order to investigate the characteristics of the anode plate of this embodiment, two anode plates h and i were prepared and tested. The anode plate h is the anode plate of this embodiment. The anode plate i is the anode plate of the comparative example manufactured by the same method as that of the anode plate of this example except that the liquid-retaining substance such as carbonized wood powder was not added. Then, each one of the anode plates h and i is laminated with one known cathode plate in which a liquid retaining material is not added to the active material through a retainer holding an electrolytic solution to form an electrode plate group. 1.4Ah lead-acid battery H, I by encapsulating the whole electrode plate group with a resin film
made. Then, the lead storage batteries H and H are repeatedly charged and discharged by discharging each lead storage battery at a final voltage of 1.74 V at 1 A and then performing constant voltage charging at 1.6 A and 2.47 V for 3.5 hours.
The cycle life characteristics of I were investigated. FIG. 11 shows the measurement result. From this figure, it can be seen that the battery H using the anode plate h of the present example has a longer cycle life characteristic than the battery I using the anode plate i of the comparative example in which the liquid retaining material is not added.

Next, the relationship between the weight ratio of the carbonized wood powder to the lead powder and the high rate discharge capacity of the battery was investigated. First, 6 types of anode plates were produced by the same method as the method for producing the anode plate h of this example, except that only the weight ratio of the carbonized wood powder to the lead oxide powder was changed within the range of 0 to 5% by weight. Then, one electrode plate of each anode plate is laminated with one known cathode plate in which a liquid retaining material is not added to the active material through a retainer holding an electrolytic solution to form an electrode plate group. The whole group was wrapped with a resin film to make six types of 1.4 Ah lead-acid batteries. Then, each lead acid battery was discharged at 4.2 A and the discharge time of each battery was measured. FIG. 12 is a diagram showing the measurement results. From this figure, it can be seen that when the weight ratio of the carbonized wood powder exceeds 3% by weight, the filling amount of the active material decreases and the high rate discharge capacity decreases.

Next, the relationship between the size of the carbonized wood powder and the capacity of the battery was investigated. First, seven kinds of anode plates were made using the active material paste to which each size of carbonized wood powder in the range of 10 mesh to 200 mesh was added. The weight ratio of the carbonized wood powder to the total weight of the lead powder of each electrode plate was 0.5%, and each electrode plate had the same structure as the electrode plate h of this embodiment except the size of the carbonized wood powder. Have Next, one plate of each anode is laminated with one plate of cathode through a retainer holding an electrolytic solution to form an electrode plate group, and the entire electrode plate group is wrapped with a resin film to form seven kinds of 1.4 Ah. Made of lead acid battery. Then, each battery was discharged at a high rate of 4.2 A and the discharge time was measured. FIG. 13 shows the measurement result. From this figure, it can be seen that the capacity of the battery decreases as the size of the carbonized wood powder becomes smaller so as to pass through a 100-mesh sieve or becomes too large to pass through a 16-mesh sieve.
It should be noted that, in place of the carbonized wood powder, wood powder having a size of 32 to 42 mesh and not subjected to carbonization treatment was used. Otherwise, in a lead acid battery made in the same manner as the lead acid battery used in this test, the discharge time was 13 It was a minute. When this result is compared with the discharge time (14 minutes) of the lead storage battery using the carbonized wood powder of 32 mesh to 42 mesh shown in this figure, the conductivity in the active material is increased by using the carbonized wood powder. ,
It can be seen that the capacity of the lead storage battery increases.

Next, the relationship between the size of the carbonized wood powder and the cycle life characteristics of the battery was investigated. A lead storage battery using 0 mesh to 16 mesh carbonized wood powder used in the above-mentioned battery capacity test and a lead storage battery using 32 mesh to 42 mesh carbonized wood powder each have a final voltage of 1A up to a final voltage of 1.74V.
The lead-acid battery was examined for cycle life characteristics by repeating charge and discharge charging and discharging in which the battery was discharged for 1 hour, and after resting for 1 hour, constant voltage charging was performed at 1.6 A and 2.47 V for 1 hour. FIG. 14 shows the measurement result. From this figure, the size of carbonized wood powder is 1
It can be seen that the cycle life characteristics deteriorate when the size becomes too large to pass through a 6-mesh sieve.

In Example 3, carbonized wood powder having an average carbonization degree of 80% was used as the liquid retaining material, but carbonized wood powder having a different carbonization degree may be used as the liquid retaining material. Is. The higher the degree of carbonization of the carbonized wood powder used, the higher the conductivity of the active material, but the lower the strength of the carbonized wood powder. Therefore, carbonized wood powder having an appropriate carbonization degree may be used depending on the application. Further, it goes without saying that a mixture of carbonized wood powder and non-carbonized wood powder can be used as the liquid retaining material. Further, in the above-mentioned Example 3, the wood powder cut without specifying the cutting direction was carbonized to produce carbonized wood powder.
As shown in the second embodiment, carbonized wood powder may be produced by carbonizing a wood powder having an elongated shape in which a plurality of temporary conduits extend in the longitudinal direction. If such carbonized wood powder is used as the liquid-retaining substance, it is possible to smooth the movement of the electrolytic solution in the active material and prevent the active material from falling off.

In each of the above embodiments, the present invention is applied to the anode plate, but it goes without saying that the present invention can also be applied to the cathode plate.

In each of the above-mentioned embodiments, the wood powder was made from a relatively inexpensive cedar tree among the softwood materials having a long tracheid, but any wood powder that can be dried to form a porous wood powder can be used. For example, not only softwood but also hardwood may be used.

[0038]

According to the first aspect of the invention, since dry porous wood powder or the like is used as the liquid retaining material, the manufacturing cost of the electrode plate can be reduced. Moreover, since the electrolytic solution can be stored in the porous portion such as wood powder, the capacity of the battery and the utilization rate of the active material can be increased. Moreover, since the wood powder and the like are dispersed throughout the active material, the stress load due to the local reaction of the active material does not increase and the life characteristics of the battery can be improved. In addition, the life characteristics of the battery can be improved by increasing the binding force between the active material and the liquid-retaining material due to the active material entering the porous portion such as wood powder. Furthermore, since the porous carbonized wood powder is electrically conductive,
When carbonized wood powder is used as the liquid-retaining substance, the content can be appropriately selected to arbitrarily increase the conductivity in the active material, thereby increasing the discharge capacity of the battery.

According to the second aspect of the present invention, since wood powder having a size of 16 to 100 mesh is used, the discharge capacity of the battery can be increased within a preferable range.

According to the third aspect of the present invention, the weight ratio of the wood powder or the like to the total weight of the lead powder used to form the active material layer is less than 3%, which greatly contributes to the improvement of the discharge capacity of the battery.

According to the fourth aspect of the present invention, since the plurality of temporary conduits are made of wood powder or the like having an elongated shape extending in the longitudinal direction, the electrolytic solution moves smoothly in the active material. Therefore, the discharge reaction proceeds almost uniformly over the entire electrode plate, the utilization rate of the active material is greatly improved, and the capacity per unit weight of the active material is increased. Further, since the shape of the end face portion where the temporary duct is exposed has a complicated shape like a honeycomb structure, the active material enters the entrance portion of the porous portion such as wood powder, and the active material and the liquid-retaining material The binding force of is greatly increased. Moreover, since the plurality of temporary conduits extend in the longitudinal direction, the bending strength of the wood powder or the like becomes high, and the slender wood powder or the like functions as a reinforcing material for the active material layer to prevent the active material from falling off. Therefore, the life characteristics of the battery can be improved.

According to the fifth aspect of the present invention, the weight ratio of the slender wood powder or the like to the active material is 0.2% or more and 1.0% or less, so that the utilization rate of the active material is increased.

According to the invention of claim 6, the utilization rate of the active material is increased because the area of the end face in the longitudinal direction of the slender wood powder or the like is set to 0.04 mm ² or more.

[Brief description of drawings]

FIG. 1 is an enlarged view of a plane orthogonal to a fiber direction of wood powder used for an electrode plate of an example of the present invention.

FIG. 2 is a diagram showing the relationship between the amount of liquid-retaining substance added to the battery used in the test and the battery capacity.

FIG. 3 is a diagram showing the relationship between the size of wood flour and the capacity of a battery.

FIG. 4 is a diagram showing the life characteristics of the battery used in the test.

FIG. 5 is a perspective view of wood powder used in an electrode plate of another embodiment of the present invention.

FIG. 6 is a view showing the active material strength of the electrode plate used in the test.

FIG. 7 is a diagram showing a utilization rate of an anode active material of a battery used in a test.

FIG. 8 is a diagram showing the life characteristics of the battery used in the test.

FIG. 9 is a diagram showing the relationship between the weight ratio of wood powder to the active material and the utilization rate of the anode active material.

FIG. 10 is a diagram showing the relationship between the area of the end face of wood powder in the longitudinal direction and the utilization rate of the anode active material.

FIG. 11 is a diagram showing cycle life characteristics of a battery used in a test.

FIG. 12 is a diagram showing the relationship between the weight ratio of carbonized wood powder to lead powder and the high rate discharge capacity of the battery.

FIG. 13 is a diagram showing the relationship between the size of carbonized wood powder and the capacity of a battery.

FIG. 14 is a diagram showing the relationship between the size of carbonized wood powder and the cycle life characteristics of a battery.

[Explanation of symbols]

 1 Porous part 10 Temporary conduit

Claims (6)

[Claims] 1. A lead storage battery electrode plate comprising a liquid-retaining substance added to an active material, wherein at least one of dried porous wood powder and porous carbonized wood powder is used as the liquid-retaining substance. An electrode plate for a lead storage battery, which is characterized in that one is used. 2. The electrode plate for a lead storage battery according to claim 1, wherein the wood powder and the carbonized wood powder have a size of 16 mesh to 100 mesh. 3. The lead-acid battery electrode according to claim 1, wherein the weight ratio of the liquid-retaining substance to the total weight of the lead oxide powder used to form the active material layer is less than 3%. Board. 4. The lead-acid battery electrode plate according to claim 1, wherein the wood powder and the carbonized wood powder are wood powder having an elongated shape in which a plurality of temporary conduits extend in a longitudinal direction. 5. The electrode plate for a lead storage battery according to claim 4, wherein a weight ratio of the liquid retaining material to the active material is 0.2% or more and 1.0% or less. 6. The lead-acid battery electrode plate according to claim 4, wherein the wood powder and the carbonized wood powder have an end face area in the longitudinal direction of 0.04 mm ² or more.