JPH09161841A - Battery having electrode body of winding structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the degree of freedom in battery design even when the winding number of an electrode body is reduced by 2-3 turns and minimize the clearance between the electrode body and a battery can to allow a higher capacity. SOLUTION: The winding center 4a of an electrode body 4 is shifted from the center of a battery can 5, whereby the clearance between the electrode body 4 and the battery can 5 is reduced. A thin part is provided in part of a positive electrode 1 or negative electrode 2, and this thin part is arranged in any position in the direction where the winding end of the electrode body 4 is present, or the direction where the sectional diameter of the cavity part in the central part of the electrode body 4 is the longest is not conformed to the direction where the winding end part of the electrode body 4 is present, whereby the ratio of shortest diameter to longest diameter of the section of the electrode body 4 approaches to 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having a spirally wound electrode body, and more particularly to a battery having a high capacity by improving the spirally wound structure of the electrode body.

[0002]

2. Description of the Related Art A spirally wound electrode body formed by spirally winding a positive electrode and a negative electrode through a separator has a large facing area between the positive electrode and the negative electrode and has good load characteristics. It is widely used in alloy batteries, nickel-cadmium batteries, lithium secondary batteries and the like.

However, recently, as devices using batteries have been downsized, and batteries have been required to be downsized accordingly, there is a demand for downsizing while keeping the standard value of the current flowing per unit area of the electrode constant. As the inner diameter of the battery can that accommodates the electrode body is reduced, the number of turns of the electrode decreases, and as a result, the number of turns of the electrode cannot be set arbitrarily and the current value of the equipment used is reduced. It is no longer possible to adopt the appropriate number of electrode windings, or the cross-sectional shape of the electrode body becomes distorted and the gap between the electrode body and the battery can becomes large, making it impossible to improve the battery capacity. Problems are starting to come up.

The two problems will be described in detail below.

For example, a separator having a thickness of 0.15 mm,
Volume ratio to the negative electrode and the amount of the active material of the negative electrode 2.
Using a positive electrode having a 1-fold amount of active material, a separator, a negative electrode, a separator, and a positive electrode are wound around a winding shaft having a diameter of 2.5 mm in the order of 2 to 3 times, and the outermost periphery of an electrode body having a wound structure. The electrode body whose end is wound with the negative electrode is manufactured, the winding shaft is extracted from the electrode body, the winding center of the electrode body is aligned with the center of the battery can, and the electrode body having the winding structure is formed into a battery having an inner diameter of 9.4 mm. It is assumed that it will be stored in a can.

In order to obtain a larger electric capacity in this battery, it is necessary to reduce the gap between the electrode body and the battery can when the wound electrode body is housed in the battery can. Since the cross-sectional shape of the wound electrode body changes depending on the number of windings of the positive electrode, the negative electrode, the separator, etc., the size of the gap between the electrode body and the battery can depends on the number of windings of those members. It will change.

6 to 9 are designed so that the battery capacity becomes maximum when the number of turns of the positive electrode is 2.3 times, 2.6 times, 2.75 times, and 2.9 times under the above-mentioned conditions. It is sectional drawing which shows typically the cross-sectional shape of the electrode body of a winding structure accommodated in the battery can.

In these cases, when the winding-structured electrode body 4 is housed in the battery can 5, the gap between the electrode body 4 and the battery can 5 is minimized when the number of windings of the positive electrode 1 is two. ．
It's 75 times. Therefore, in the prior art, the number of turns of the positive electrode 1 is set to 2.75 so that the gap between the electrode body 4 and the battery can 5 is minimized. We never adopted 2.9 times, 2.6 times, 2.3 times, etc.

The number of turns of the positive electrode for reducing the gap between the wound electrode body and the battery can is other than 2.75, 1.75 times, 3.75 times, 4.75 times. The number of turns of the positive electrode is 2 to 3 here. That is, there is a number of turns that reduces the gap as described above, except when the number of turns of the positive electrode is 2 to 3, but in the electrode body having a wound structure, the smaller the number of turns, the cross section of the electrode body. Since the shape becomes distorted and a gap is apt to be formed between the electrode body and the battery can, in the present invention, the case where the number of turns of the positive electrode is 2 to 3 times is selected and studied. However, the present invention is not limited to the case where the number of turns of the positive electrode is 2 to 3 times.

As can be seen from the above example, when the number of windings of the electrodes such as the positive electrode and the negative electrode is limited within a certain range, when the electrode body having the winding structure is housed in the battery can, the electrode body and the battery can are separated from each other. In order to reduce the gap between the electrodes, the number of turns of the electrode is limited to a certain value.

On the other hand, when an electrode body having a winding structure having a predetermined cross-sectional area is produced using a separator having a predetermined thickness without considering the accommodation of the winding structure electrode body in a battery can, the number of windings is small. The higher the electric capacity. This is because when a separator having a constant thickness is used, the volume ratio of the separator occupying in the electrode body decreases when the number of windings of the electrode body having the winding structure is reduced, so that the active material filling amount of the positive electrode or the negative electrode can be increased. This is because the battery capacity can be improved.
Further, when the number of windings is small, the electrode thickness increases, and if the weight per unit area (basis weight) of the electrode base material is constant, the ratio of the active material in the electrode increases as the electrode thickness increases. .

However, when the number of windings of the electrode is small, the area of the facing portion of the positive electrode and the negative electrode is small, and the load characteristics are deteriorated. Therefore, when discharging at a large current value, the number of windings of the electrode is reduced. It is preferable to increase the facing area between the positive electrode and the negative electrode by increasing the number. Therefore, when commercializing a battery, an optimum value of the number of turns exists from the viewpoint of the balance between the electric capacity and the load characteristic.

Therefore, when the electrode body is housed in the battery can when the number of windings of the electrode is small, the number of windings of the electrode is limited to a specific value, which means that the electrode winding suitable for the current value of the equipment used. The problem arises that numbers cannot be adopted. In addition, as the number of windings of the electrode is smaller, the cross-sectional shape of the electrode body shifts from a circular shape to a distorted shape, and when the electrode body is housed in the battery can, the gap between the electrode body and the battery can becomes large. However, this is a problem in improving the battery capacity.

[0014]

As described above, in a battery using an electrode body having a winding structure, when the number of windings of the electrode body is reduced, the number of windings cannot be set arbitrarily, so that the current value of the equipment used. The problem that it is not possible to adopt the number of electrode windings that is suitable for, and the problem that the gap between the electrode body and the battery can becomes large because the cross-sectional shape of the electrode body becomes distorted, and the battery capacity cannot be improved. was there.

Therefore, according to the present invention, even when the number of windings of the electrode body is reduced to 2 to 3 times, the degree of freedom in the battery design is increased, and the gap between the electrode body and the battery can is reduced to achieve high efficiency. It is an object of the present invention to provide a battery having a higher capacity.

[0016]

DISCLOSURE OF THE INVENTION The present invention relates to a battery in which an electrode body having a wound structure is housed in a battery can, by shifting the winding center of the electrode body and the center of the battery can to form an electrode body and a battery can. The space between them is reduced to improve the battery capacity.

That is, since the winding center of the electrode body and the center of the battery can deviate from each other, the gap between the distorted electrode body and the battery can having a circular cross section is small. Become.

The distance between the winding center of the electrode body and the center of the battery can is preferably 4% or more of the inner diameter of the battery can. That is, when the distance between the center of winding of the electrode body having the above-described winding structure and the center of the battery can is 4% or more of the inner diameter of the battery can, the deviation of the cross-sectional shape of the electrode body from the circular shape is easily absorbed, and the electrode body is easily absorbed. The space between the battery can and the battery can becomes smaller. However, if the above distance becomes too large, the gap between the electrode body and the battery can tends to increase, so the distance between the winding center of the electrode body having the above winding structure and the center of the battery can is rather large. It is preferable that the inner diameter of the battery can be 4% or more and 9% or less.

Further, according to the present invention, by taking measures to correct the deviation of the cross-sectional shape of the wound electrode body from the circular shape, the gap between the electrode body and the battery can can be further reduced, and the battery can be made smaller. This is an improvement in capacity.

As a means for correcting the deviation of the cross-sectional shape of the electrode body from a circular shape and bringing it closer to a circular shape, for example, the following may be mentioned.

The direction in which the diameter of the cross section of the wound electrode body is the largest is the direction in which the electrode end exists when the winding center side is the starting point side, that is, the winding end of the wound electrode body. The direction in which the part exists. Therefore, if a portion having a small thickness is provided somewhere in the direction in which the winding end portion of the wound structure electrode body exists, the ratio of the shortest diameter to the longest diameter of the wound structure electrode body can be brought close to 1. Therefore, the sectional shape of the electrode body can be approximated to a circle.

Specifically, when the electrode base material is applied and filled with the electrode active material during the production of the electrode, the electrode active material is not locally applied or filled, or the application or filling is uniformly performed. By doing so, the electrode with locally thinned thickness is produced, and if the thinned portion is placed somewhere in the direction in which the winding end portion of the electrode body exists, the longest diameter of the electrode body can be reduced. Therefore, the ratio of the shortest diameter and the longest diameter of the cross section of the wound electrode body can be brought close to 1. As a result, the cross-sectional shape of the electrode body can be approximated to a circle, and the gap between the electrode body and the battery can can be reduced.

Further, the winding shaft around which the positive electrode, the negative electrode, the separator, etc. are wound is formed into an elliptical shape instead of a circular shape to prepare an electrode body having a wound structure, and the winding body is wound from the electrode body. When the shaft is removed, by making the direction in which the diameter of the cross-section of the cavity formed in the center of the wound electrode body becomes the largest and the direction in which the winding end portion of the electrode body exists, do not match. It is possible to reduce the longest diameter of the cross section of the electrode body having the winding structure and to make the ratio of the shortest diameter and the longest diameter of the cross section of the electrode body close to 1, and reduce the gap between the electrode body and the battery can. be able to.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described more specifically with reference to Examples. However, the present invention is not limited to only these examples.

Example 1 A paste type hydrogen storage alloy electrode having a known structure and a thickness of 0.295 mm was used as a negative electrode, and the active material was 2.1 times in volume ratio with respect to the amount of the active material of the negative electrode in the known structure. A paste type nickel hydroxide electrode having a thickness of 0.530 mm and a partially thinned portion is used as a positive electrode, and a polyamide non-woven fabric having a known structure and a thickness of 0.15 mm is used as a separator.
The positive electrode and the negative electrode are spirally wound via a separator,
The number of windings of the positive electrode was 2.5, and the outermost peripheral portion was wound around the negative electrode to prepare an electrode body having a winding structure.

In manufacturing the above-mentioned wound electrode body,
A rod having a circular cross section with a diameter of 2.5 mm was used as a winding shaft around which members such as the positive electrode, the negative electrode, and the separator were wound, and after the electrode body was manufactured, the winding shaft was extracted from the electrode body. And
The electrode body having the winding structure was housed in a battery can having a size of AAA and an inner diameter of 9.4 mm. The cross section of the electrode body in that state is schematically shown in FIG.

Referring to FIG. 1, reference numeral 1 is a positive electrode, 2 is a negative electrode, 3 is a separator, and 4 is a winding formed by spirally winding the positive electrode 1 and the negative electrode 2 through the separator 3. The structure is an electrode body, and 4a is the winding center of the electrode body 4. And 5 is a battery can and 5a is the center of the battery can 5. However, only the inner peripheral surface of the battery can 5 is shown by a thin line. This also applies to FIGS. 3 to 9 described later.

In this electrode body 4, the positive electrode 1 is locally thinned without forming an active material layer on a part of the base material.
By arranging the thin portion in the direction in which the diameter of the cross section of the electrode body 4 is the longest, that is, in the direction in which the winding end portion exists, the longest diameter of the cross section of the electrode body 4 is reduced. The ratio of the shortest diameter to the longest diameter is set to 1: 1.05, and the winding center 4a of the electrode body 4 is displaced from the center 5a of the electrode can 5 by a distance corresponding to 6.8% of the inner diameter of the battery can 5. . The ratio of the shortest diameter to the longest diameter of the cross section of the electrode body 4 when the thickness of the positive electrode 1 is not partially reduced is 1:
It was 10.

Further, FIG. 1 is a schematic illustration, and although the present invention is characterized in that the gap between the electrode body 4 and the battery can 5 is made small, this FIG. In the figure, a considerably large gap is shown between the electrode body 4 and the battery can 5, but this is because the positive electrode 1, the negative electrode 2, the separator 3, etc., which are thin in thickness, have a certain thickness. The reason is that the large voids shown in the figure cannot be formed. This will be described later with reference to FIG.
The same applies to FIG. 5 and the like.

A 30% aqueous potassium hydroxide solution was used as the electrolytic solution, the electrode body having the above-mentioned winding structure was housed in a battery can, and 0.85 ml of the above electrolytic solution was injected. Form, a nickel-hydrogen storage alloy-based alkaline secondary battery was produced. The structure of this battery is schematically shown in FIG.

Referring to FIG. 2, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator, 4 is an electrode body having a winding structure, 5 is a battery can, 6 is an annular gasket, 7 is a battery lid, and 8
Is a terminal plate, 9 is a sealing plate, 10 is a metal spring, 11 is a valve body,
Reference numeral 12 is a positive electrode lead body, 13 is an insulator, and 14 is an insulator.

The positive electrode 1 is made of a paste type nickel electrode as described above, and the negative electrode 2 is made of a paste type hydrogen storage alloy electrode as described above. The separator 3 is made of polyamide nonwoven fabric as described above, and the positive electrode 1 and the negative electrode 2 are spirally wound through the separator 3 to be housed in the battery can 5 as the wound electrode body 4. The insulator 14 is disposed on the top of the insulator 14.

The annular gasket 6 is made of nylon 66, the battery lid 7 is composed of the terminal plate 8 and the sealing plate 9, and the opening of the battery can 5 is sealed by the battery lid 7 and the annular gasket 6. There is.

That is, the wound electrode assembly 4 is placed inside the battery can 5.
After inserting the insulator 14 and the like, an annular groove 5b having a bottom protruding toward the inner peripheral side is formed in the vicinity of the open end of the battery can 5.
The annular gasket 6 and the battery lid 7 are arranged in the opening of the battery can 5 by supporting the lower portion of the annular gasket 6 with the inner peripheral side protruding portion of the groove 5b, and the portion beyond the groove 5a of the battery can 5 is placed inside. It is tightened in one direction and the opening of the battery can 5 is sealed by the battery lid 7 and the annular gasket 6.

The terminal plate 8 is provided with a gas discharge hole 8a, and the sealing plate 9 is provided with a gas detection hole 9a.
A metal spring 10 and a valve body 11 are arranged between the metal plate 10 and the sealing plate 9. Then, the outer peripheral portion of the sealing plate 9 is bent to sandwich the outer peripheral portion of the terminal plate 8, thereby fixing the terminal plate 8 and the sealing plate 9.

Under normal circumstances, this battery is a metal spring 1
Since the valve body 11 closes the gas detection hole 9a by the pressing force of 0, the inside of the battery is kept in a sealed state. However, when gas is generated inside the battery and the battery internal pressure rises abnormally, The metal spring 10 contracts and the valve body 11 and the gas detection hole 9a
A gap is created between the gas detection hole 9a and the gas inside the battery.
And is discharged outside the battery through the gas discharge hole 8a,
It is configured to prevent battery rupture.

One end of the positive electrode lead body 12 is spot-welded to a current collector (tab) made of a nickel ribbon spot-welded to the end of the positive electrode 2, and the other end is attached to the lower end of the sealing plate 9. By spot welding, the terminal plate 8 acts as a positive electrode terminal by contact with the sealing plate 9.

As described above, the outermost peripheral portion of the wound electrode body is composed of the negative electrode, and the outer surface of the outermost peripheral portion of the negative electrode 2 has the metal base material exposed although not shown. hand,
The base material contacts the inner wall of the battery can 5, whereby the battery can 5 acts as a negative electrode terminal. In addition, this FIG. 2 also
It is a schematic diagram, and the positions and dimensions are slightly different from those in FIG. 1 for easy understanding of each member.

Example 2 A paste type hydrogen storage alloy electrode having a known structure and a thickness of 0.305 mm was used as a negative electrode, and the active material having a known structure and a volume ratio of 2.1 times the active material amount of the negative electrode was used. Using a paste type nickel hydroxide electrode having a thickness of 0.535 mm as a positive electrode, a positive electrode and a negative electrode are spirally wound around a winding shaft having a circular cross section with a diameter of 2.5 mm through a separator to wind the positive electrode. The number of times was set to 2.3, and an electrode body having a winding structure in which the outermost peripheral portion was wound with the negative electrode was produced.

After the electrode body having the above-mentioned winding structure was produced, the winding shaft was taken out, and the electrode body was inserted into a battery can having a size of AAA and an inner diameter of 9.4 mm. A cross section of the electrode body in that state is schematically shown in FIG. The positive electrode and the negative electrode used in the production of the above electrode body were the same as the positive electrode and the negative electrode used in Example 1 except that the thickness was different, and the separator including the thickness was used in Example 1. Is similar to.

Now, referring to FIG. 3, as in the case of FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator,
4 is an electrode body having a winding structure, 4a is the winding center thereof, 5 is a battery can, and 5a is the center thereof. However, in the case of the electrode body shown in FIG. 3, the winding center 4a of the electrode body 4 and the center 5a of the battery can 5 are displaced by a distance corresponding to 6.8% of the inner diameter of the battery can 5. In this state of 6.8% shift, the thickness of the positive electrode 1 and the negative electrode 2 could not be made thicker than the above.

Example 3 A paste type hydrogen storage alloy electrode having a known structure and a thickness of 0.280 mm was used as a negative electrode, and the active material was 2.1 times in volume ratio with respect to the amount of the active material of the negative electrode in the known structure. Using a paste type nickel hydroxide electrode having a thickness of 0.495 mm as a positive electrode, a positive electrode and a negative electrode are spirally wound around a winding shaft having a circular cross section with a diameter of 2.5 mm through a separator to wind the positive electrode. The number of times was set to 2.4, and an electrode body having a winding structure in which the outermost peripheral portion was wound with the negative electrode was produced.

After the electrode body having the above-mentioned winding structure was produced, the winding shaft was taken out, and the electrode body was inserted into a battery can having a size of AAA and an inner diameter of 9.4 mm. The cross section of the electrode body in that state is schematically shown in FIG. The positive electrode and the negative electrode used in the production of the above electrode body were the same as the positive electrode and the negative electrode used in Example 1 except that the thickness was different, and the separator including the thickness was used in Example 1. It is similar to the one.

Referring to FIG. 4, as in the case of FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator,
4 is an electrode body having a winding structure, 4a is the winding center thereof, 5 is a battery can, and 5a is the center thereof. However, in the case of the electrode body shown in FIG. 4, the winding center 4a of the electrode body 4 and the center 5a of the battery can 5 are displaced by a distance corresponding to 4% of the inner diameter of the battery can 5. In addition, in the state of being displaced by 4%, the thickness of the positive electrode 1 and the negative electrode 2 could not be made thicker than the above.

Example 4 A paste type hydrogen storage alloy electrode having a known structure and a thickness of 0.300 mm was used as a negative electrode, and the active material was 2.1 times in volume ratio to the amount of the active material of the negative electrode in the known structure. A paste type nickel hydroxide electrode having a thickness of 0.530 mm is used as a positive electrode, and a positive electrode and a negative electrode are spirally wound through a separator on an elliptical winding shaft having a long diameter of 2.7 mm and a short diameter of 2.3 mm. And the number of turns of the positive electrode was set to 2.4, and an electrode body having a wound structure in which the outermost peripheral portion ended with the negative electrode was produced.

After the electrode body having the above-mentioned winding structure was produced, the winding shaft was extracted, and the electrode body was inserted into a battery can having a size of AAA and an inner diameter of 9.4 mm. The cross section of the electrode body in that state is schematically shown in FIG. The positive electrode and the negative electrode used in the production of the above electrode body were the same as the positive electrode and the negative electrode used in Example 1 except that the thickness was different, and the separator including the thickness was used in Example 1. It is similar to the one.

Now, referring to FIG. 5, as in the case of FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator,
4 is an electrode body having a winding structure, 4a is the winding center thereof, 5 is a battery can, and 5a is the center thereof. However, in the case of the electrode body shown in FIG. 5, the winding center 4a of the electrode body 4 and the center 5a of the battery can 5 are displaced by a distance corresponding to 6.6% of the inner diameter of the battery can 5. In addition, the direction in which the diameter of the cross section of the hollow portion (the hollow portion formed by extracting the winding shaft) in the central portion of the electrode body 4 is the longest and the direction in which the winding end portion of the winding structure electrode body exists. Without matching, the ratio of the shortest diameter to the longest diameter of the cross section of the wound electrode body is set to 1: 1.03. When the cross section of the winding shaft was a perfect circle, the ratio of the shortest diameter to the longest diameter of the cross section of the electrode body was 1: 1.13. Further, as described above, the winding center 4a of the electrode body 4 and the battery can 5 are
In the state where the center 5a of the above was shifted by 6.6%, the thickness of the positive electrode 1 and the negative electrode 2 could not be made thicker than the above.

Comparative Example 1 A paste type hydrogen storage alloy electrode having a known structure and a thickness of 0.250 mm was used as a negative electrode, and the active material was 2.1 times in volume ratio with respect to the amount of the active material of the negative electrode in the known structure. Using a paste type nickel hydroxide electrode having a thickness of 0.430 mm as a positive electrode, a positive electrode and a negative electrode are spirally wound around a winding shaft having a circular cross section with a diameter of 2.5 mm through a separator to wind the positive electrode. The number of times was set to 2.3, and an electrode body having a winding structure in which the outermost peripheral portion was wound with the negative electrode was produced.

After the electrode body having the above-mentioned winding structure was produced, the winding shaft was extracted, and the electrode body was inserted into a battery can having a size of AAA and an inner diameter of 9.4 mm. However, when inserting the electrode body into the battery can, the winding center of the electrode body was aligned with the center of the battery can. The cross section of the electrode body in that state is shown in FIG.
Is schematically shown in. The positive electrode and the negative electrode used in the production of the above electrode body were the same as the positive electrode and the negative electrode used in Example 1 except that the thickness was different, and the separator including the thickness was used in Example 1. It is similar to the one.

Referring to FIG. 6, as in the case of FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator,
Reference numeral 4 is an electrode body having a wound structure, and 5 is a battery can. However, in the case of FIG. 6, since the winding center of the electrode body 4 and the center of the battery can 5 are aligned, they are not shown.
In this way, in the state where the number of turns of the positive electrode is set to 2.3 and the center of winding of the electrode body 4 and the center of the battery can 5 are aligned with each other, the thickness of the positive electrode 1 and the negative electrode 2 is not less than the above. It couldn't be thickened.

Comparative Example 2 A paste-type hydrogen storage alloy electrode having a known structure and a thickness of 0.250 mm was used as the negative electrode, and the active material was 2.1 times in volume ratio with respect to the amount of the active material of the negative electrode in the known structure. Using a paste type nickel hydroxide electrode having a thickness of 0.430 mm as a positive electrode, a positive electrode and a negative electrode are spirally wound around a winding shaft having a circular cross section with a diameter of 2.5 mm through a separator to wind the positive electrode. The number of times was set to 2.6, and an electrode body having a winding structure in which the outermost peripheral portion was wound with the negative electrode was produced.

After the electrode body having the above-mentioned winding structure was produced, the winding shaft was taken out, and the electrode body was inserted into a battery can having a size of AAA and an inner diameter of 9.4 mm. However, when inserting the electrode body into the battery can, the winding center of the electrode body was aligned with the center of the battery can. The cross section of the electrode body in that state is shown in FIG.
Is schematically shown in. The positive electrode and the negative electrode used in the production of the above electrode body were the same as the positive electrode and the negative electrode used in Example 1 except that the thickness was different, and the separator including the thickness was used in Example 1. It is similar to the one.

Referring to FIG. 7, as in the case of FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator,
Reference numeral 4 is an electrode body having a wound structure, and 5 is a battery can. However, in the case of FIG. 7, since the winding center of the electrode body 4 and the center of the battery can 5 are aligned, they are not shown.
In this way, when the number of turns of the positive electrode is set to 2.6 and the center of winding of the electrode body 4 and the center of the battery can 5 are aligned with each other, the thickness of the positive electrode 1 and the negative electrode 2 is not less than the above. Couldn't be thicker.

Comparative Example 3 A paste type hydrogen storage alloy electrode having a known structure and a thickness of 0.250 mm was used as a negative electrode, and the active material was 2.1 times in volume ratio with respect to the amount of the active material of the negative electrode in the known structure. Using a paste type nickel hydroxide electrode having a thickness of 0.430 mm as a positive electrode, a positive electrode and a negative electrode are spirally wound around a winding shaft having a circular cross section with a diameter of 2.5 mm through a separator to wind the positive electrode. The number of electrodes was set to 2.75, and an electrode body having a winding structure in which the outermost peripheral portion was wound with the negative electrode was produced.

The number of turns of the positive electrode is 2.75, the thickness of the positive electrode is 1.7 times that of the negative electrode, and the number of turns of the positive electrode is 2 to 3 times. The number of turns of the positive electrode is such that the battery capacity is maximum under the condition that the electrode body is inserted into the battery can without shifting the center of the battery can.

After the electrode body having the above-mentioned winding structure was produced, the winding shaft was taken out, and the electrode body was inserted into a battery can having a size of AAA and an inner diameter of 9.4 mm. However, when inserting the electrode body into the battery can, the winding center of the electrode body was aligned with the center of the battery can. FIG. 8 shows a cross section of the electrode body in that state.
Is schematically shown in. The positive electrode and the negative electrode used in the production of the above electrode body were the same as the positive electrode and the negative electrode used in Example 1 except that the thickness was different, and the separator including the thickness was used in Example 1. It is similar to the one.

Now, referring to FIG. 8, as in the case of FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator,
Reference numeral 4 is an electrode body having a wound structure, and 5 is a battery can. However, in the case of FIG. 8, since the winding center of the electrode body 4 and the center of the battery can 5 are aligned, they are not shown.
In this manner, in the state where the number of turns of the positive electrode is 2.75 and the center of winding of the electrode body 4 and the center of the battery can 5 are aligned with each other, the thickness of the positive electrode 1 and the negative electrode 2 is not less than the above. It couldn't be thickened.

Comparative Example 4 A paste type hydrogen storage alloy electrode having a known structure and a thickness of 0.245 mm was used as a negative electrode, and the active material was 2.1 times in volume ratio to the amount of the active material of the negative electrode in the known structure. Using a paste type nickel hydroxide electrode having a thickness of 0.420 mm as a positive electrode, a positive electrode and a negative electrode are spirally wound around a winding shaft having a circular cross section with a diameter of 2.5 mm through a separator to wind the positive electrode. The number of electrodes was set to 2.75, and an electrode body having a winding structure in which the outermost peripheral portion was wound with the negative electrode was produced.

After the electrode body having the above-mentioned winding structure was produced, the winding shaft was taken out, and the electrode body was inserted into a battery can having a size of AAA and an inner diameter of 9.4 mm. However, when inserting the electrode body into the battery can, the winding center of the electrode body was aligned with the center of the battery can. The cross section of the electrode body in that state is shown in FIG.
Is schematically shown in. The positive electrode and the negative electrode used in the production of the above electrode body were the same as the positive electrode and the negative electrode used in Example 1 except that the thickness was different, and the separator including the thickness was used in Example 1. It is similar to the one.

Now, referring to FIG. 9, as in the case of FIG. 1, 1 is a positive electrode, 2 is a negative electrode, 3 is a separator,
Reference numeral 4 is an electrode body having a wound structure, and 5 is a battery can. However, in the case of FIG. 9, since the winding center of the electrode body 4 and the center of the battery can 5 are aligned, they are not shown.
In this way, in the state where the number of turns of the positive electrode is 2.9 and the center of winding of the electrode body 4 and the center of the battery can 5 are aligned with each other, the thickness of the positive electrode 1 and the negative electrode 2 is set to the above or more. It couldn't be thickened.

Next, the above Examples 1 to 4 and Comparative Example 1
After the ~ 4 battery was charged at 100 mA for 7 hours, and then discharged at 25 ° C at a discharge current of 10 mA until the voltage reached 1.0 V, the discharge capacity and the discharge current at 100 mA reached a voltage of 1.0 V. Check the discharge capacity when discharged,
In addition, the discharge current was set to a large current of 400 mA and the voltage was 1.0
The discharge capacity when discharged to V was examined. Table 1 shows the results.

[0062]

[Table 1]

As shown in Table 1, the batteries of Examples 1 to 4 have a larger discharge capacity than the battery of Comparative Example 3 having the maximum discharge capacity of the conventional battery, and also discharge at a large current discharge of 400 mA. Although the capacity was large and the number of turns of the positive electrode was smaller than that of the battery of Comparative Example 3, the load characteristics were not deteriorated.

[0064]

As described above, according to the present invention, it is possible to achieve high capacity in a battery having an electrode body having a wound structure.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a wound electrode body used in the battery of Example 1 in a battery can.

FIG. 2 is a cross-sectional view schematically showing the alkaline secondary battery of Example 1.

FIG. 3 is a cross-sectional view schematically showing a wound electrode body used in the battery of Example 2 in a battery can.

FIG. 4 is a cross-sectional view schematically showing a wound electrode body used in the battery of Example 3 in a battery can.

FIG. 5 is a cross-sectional view schematically showing a wound electrode body used in the battery of Example 4 in a battery can.

FIG. 6 is a cross-sectional view schematically showing a wound electrode body used in the battery of Comparative Example 1 housed in a battery can.

FIG. 7 is a cross-sectional view schematically showing a wound electrode body used in the battery of Comparative Example 2 housed in a battery can.

FIG. 8 is a cross-sectional view schematically showing a wound electrode body used in the battery of Comparative Example 3 in a battery can.

FIG. 9 is a cross-sectional view schematically showing a wound electrode body used in the battery of Comparative Example 4 in a battery can.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode 2 Negative electrode 3 Separator 4 Winding structure electrode body 4a Winding center of electrode body 5 Battery can 5a Center of battery can

Claims (4)

[Claims] 1. A battery in which an electrode body having a spiral structure in which a positive electrode and a negative electrode are spirally wound with a separator interposed between the positive electrode and the negative electrode is housed in a battery can. A battery having an electrode body having a wound structure, which is characterized by being offset. 2. The battery according to claim 1, wherein the distance between the winding center of the electrode body having the winding structure and the center of the battery can is 4% or more of the inner diameter of the battery can. 3. The battery according to claim 1, wherein a thin portion is provided on a part of the positive electrode or the negative electrode, and the thin portion is located somewhere in the direction in which the winding end portion of the electrode body having the winding structure exists. The battery is characterized in that the ratio of the shortest diameter to the longest diameter of the cross-section of the electrode body having the winding structure is brought close to 1 by arranging the electrode in the. 4. The battery according to claim 1, wherein the diameter of the cross section of the hollow portion at the center of the wound electrode body is longest and the winding end portion of the wound electrode body is present. The battery is characterized in that the ratio of the shortest diameter to the longest diameter of the cross-section of the electrode body having the winding structure is brought close to 1 by not matching.