JP3439031B2 - Inside-out type battery - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inside-out type battery in which a negative electrode whose volume is reduced by discharge of a battery is located on the outer peripheral side of a positive electrode whose volume is increased by discharge of the battery via a separator.

[0002]

2. Description of the Related Art Inside-out type batteries, in which the other electrode is located on the outer peripheral side of one electrode via a separator, generally have a larger discharge capacity than a coin-type battery in which positive and negative electrodes are stacked via a separator, The structure is simpler and cheaper than the spiral type battery, which has a spiral shape with a separator interposed therebetween. Therefore, the inside-out type battery is widely used in electronic devices. Among them, a manganese dioxide-lithium battery using manganese dioxide as a positive electrode active material and lithium as a negative electrode active material is widely used for memory backup and the like.

A substantially columnar positive electrode whose volume increases as the battery discharges; a substantially cylindrical negative electrode whose volume decreases as the battery discharges;
A substantially cylindrical separator that separates the positive electrode and the negative electrode is provided, and the outer peripheral side surface of the positive electrode and the inner peripheral side surface of the separator face each other, and the outer peripheral side surface of the separator and the inner peripheral side surface of the negative electrode face each other. As an inside-out type battery in which the negative electrode is located on the outer peripheral side through a separator, there is, for example, the one described in Japanese Utility Model Laid-Open No. 58-66567.

In this type of battery, the distance between the positive and negative electrodes is usually made as short as possible in order to increase the reaction efficiency of the positive and negative electrodes. Further, in the separator, the positive electrode is wound around the outer peripheral side surface of the positive electrode so as to form a substantially tubular shape, and the superposed portion is firmly bonded. As a result, the increase in the volume of the positive electrode in the outer peripheral direction is hardly hindered by the separator. Therefore, as the battery discharges, the volume of the negative electrode decreases from the side facing the positive electrode, the distance between the positive and negative electrodes increases, and the reaction efficiency of the positive and negative electrodes decreases. Also, the fact that the increase in volume in the outer peripheral direction of the positive electrode is hindered by the separator means that the separator exerts a pressing force. Therefore, if the strength of the separator is weaker than this pressing force, the separator is damaged and the positive and negative electrodes are short-circuited. There is also a problem.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a substantially columnar positive electrode whose volume increases as the battery discharges, a substantially cylindrical negative electrode whose volume decreases as the battery discharges, and a separator for separating the positive electrode and the negative electrode. A cylindrical separator is provided, and while the outer peripheral side surface of the positive electrode and the inner peripheral side surface of the separator face each other, and the outer peripheral side surface of the separator and the inner peripheral side surface of the negative electrode face each other, the negative electrode via the separator on the outer peripheral side of the positive electrode. The present invention solves the above-mentioned problems relating to the inside-out type battery in which is located, and provides an inside-out type battery of this type in which the reaction efficiency of the positive and negative electrodes is good.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a substantially columnar positive electrode whose volume increases as the battery discharges, a substantially cylindrical negative electrode whose volume decreases as the battery discharges, and a separator for separating the positive electrode and the negative electrode. A cylindrical separator is provided, and while the outer peripheral side surface of the positive electrode and the inner peripheral side surface of the separator face each other, and the outer peripheral side surface of the separator and the inner peripheral side surface of the negative electrode face each other, the negative electrode via the separator on the outer peripheral side of the positive electrode. Is located, and the separator is
It is characterized in that it has a superposed portion on the side surface that slides as the volume of the positive electrode increases in the outer peripheral direction.

When the positive electrode has a substantially cylindrical shape, it is preferable that the member that counteracts the increase in volume in the inner peripheral direction of the positive electrode is in contact with 30% or more of the area of the inner peripheral side surface of the positive electrode.

[0008]

First of all, it will be mentioned that the separator has on its side surface a polymerized portion that slides due to an increase in the outer peripheral volume of the positive electrode.

With this structure, the overlapped portion of the separator slides and the side surface of the separator expands due to the increase in the volume of the positive electrode in the outer peripheral direction, so that the increase in the outer peripheral volume of the positive electrode is not hindered by the separator. Therefore, even if the negative electrode facing the positive electrode decreases due to the discharge of the battery, the volume of the positive electrode, which increases in volume due to the discharge of the battery, increases toward the negative electrode located on the outer peripheral side thereof, so that the distance between the positive and negative electrodes becomes long. Can be prevented. At the same time, the area of the positive and negative electrodes facing each other increases due to the increase in the volume of the positive electrode in the outer peripheral direction. Therefore, by preventing the distance between the positive and negative electrodes from increasing and increasing the facing area of the positive and negative electrodes,
The reaction efficiency of the positive and negative electrodes is improved.

Further, with this structure, since the compressive force is less likely to be exerted on the separator, it is possible to prevent the separator from being damaged.

Next, in the case where the positive electrode has a substantially cylindrical shape, it is preferable that the member that counteracts the increase in volume of the positive electrode in the inner circumferential direction is in contact with 30% or more of the area of the inner circumferential side surface of the positive electrode. Mention.

[0012] In this type of inside-out type battery, a structure in which the positive electrode has a substantially cylindrical shape is generally adopted in order to provide a liquid retaining portion for the electrolytic solution and a large contact area of the current collector. . However, if the positive electrode has a substantially cylindrical shape, the amount of increase in volume of the positive electrode is consumed also in the inner circumferential direction. That is, the amount of increase in volume of the positive electrode to the negative electrode side is reduced. Therefore, in order to suppress this decrease, a member that counteracts the increase in volume in the inner circumferential direction of the positive electrode is brought into contact with 30% or more of the area of the inner circumferential side surface of the positive electrode.

The member that counteracts the increase in the volume of the positive electrode in the inner peripheral direction is a member that is hardly deformed or moved by the force of this increase in volume. In other words, it is a member that can almost prevent the inner peripheral side surface of the positive electrode that is in contact with this member from increasing in volume in the central axis direction of the hollow portion. vice versa,
The member that does not react to the increase in the volume of the positive electrode in the inner circumferential direction is, for example, because it is soft, it is extremely deformed by the force of the increase in the volume of the positive electrode, or is moved extremely toward the central axis of the hollow part by the force of the increase in the volume of the positive electrode. Or, the inner peripheral side surface of the positive electrode in contact with this member is extremely increased in volume in the central axis direction of the hollow portion,
It is a member that cannot be prevented.

Considering the above and utilization as a current collector, stainless steel having a predetermined shape or aluminum having a predetermined shape is desirable as the reaction member.

The reaction member may have a hole for allowing the electrolytic solution to penetrate into the positive electrode.

As a negative electrode whose volume is reduced by the discharge of the battery, there is a negative electrode whose active material is a light metal such as lithium or sodium which becomes an ion by the discharge of the battery and enters into the crystal of the positive electrode active material. As the positive electrode whose volume increases due to discharge of the battery, metal oxides such as manganese dioxide, fluorinated graphite, titanium sulfide, etc. that allow the negative electrode active material that has become ions due to discharge of the battery to enter into the crystal, fluoride, sulfide There are some which use as an active material.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. However, the following examples embody the technical idea of the present invention and do not limit the present invention.

FIG. 1 is a schematic structural sectional view of an inside-out type battery according to the present invention, and FIG. 2 is an XX sectional view of FIG.

[Example 1] An inside-out type battery of the present invention having a cylindrical shape with a crimp seal was manufactured. By the way, this time, the inside-out type battery of the present invention was produced in a crimp-sealed cylindrical shape, but the effects of the present invention can be obtained with either a laser sealing or a prismatic shape.

[Production of Positive Electrode with Current Collector] Manganese dioxide as an active material, graphite as a conductive material, and fluororesin as a binder were mixed at a weight ratio of 85: 10: 5, A positive electrode mixture to be the positive electrode 1 was produced. And this positive electrode mixture, cylindrical thickness (value obtained by subtracting the inner diameter from the outer diameter)
A cylindrical shape is obtained by press-molding a positive electrode mixture from a current collector 2 made of stainless steel (SUS304) of 0.2 mm (a member that counteracts the increase in volume of the positive electrode in the inner circumferential direction according to claim 2). Collector-attached positive electrode (outer diameter: 12 mm; inner diameter: 3.5) in which the outer peripheral side surface of the current collector 2 is in contact with the inner peripheral side surface of the positive electrode 1.
mm; height: 27 mm). The outer peripheral side surface of the current collector 2 is in contact with 100% of the area of the inner peripheral side surface of the positive electrode 1. Next, the positive electrode with the current collector was kept at 200 ° C. for 3 hours.
It was vacuum dried for an hour.

[Preparation of Negative Electrode] A strip-shaped lithium metal plate cut into a predetermined size was rolled to prepare a substantially cylindrical negative electrode 3.

[Preparation of Non-Aqueous Electrolyte] Propylene carbonate (PC) and 1,2-dimethoxyethane (DM
Lithium perchlorate (LiClO ₄ ) was dissolved in a solvent mixed with E) at a volume ratio of 2: 1 at a ratio of 1 mol / liter to prepare a non-aqueous electrolyte solution.

[Preparation of Sealing Plate with Lead Terminal] The lead terminal 5 was spot-welded to the dish-shaped sealing plate 4 which also serves as the positive electrode terminal of the battery to prepare a sealing plate with lead terminal. The sealing plate 4 is made of stainless steel (SUS304), and the lead terminal 5 is made of elastic stainless steel (SUS304-CS).
Article P).

[Preparation of Separator] A strip-shaped polypropylene (PP) -polyethylene (PE) non-woven fabric is rolled so as to have a polymerized portion (overlapping portion) 6, and a substantially cylindrical separator having a polymerized portion 6 and having a predetermined size. 7 was produced. The area of the overlapping portion 6 is sufficiently set in consideration of the increase in volume of the positive electrode 1 in the outer peripheral direction. By the way, this time, a separator 7 of a substantially cylindrical shape having no bottom was made with one separator. However, even if the separator 7 is composed of a plurality of separators, a method such as closing one of the open parts by folding the separator is used. There is no problem even if it is bottomed. That is, the effect of the present invention can be obtained if the overlapping portion that slides with the increase in the outer peripheral direction volume of the positive electrode is provided on the substantially cylindrical side surface.

[Assembly of Battery] On the inner bottom surface of the nickel-plated iron outer can 8, an insulating plate 9 covering substantially the entire inner bottom surface is provided. The negative electrode 3 was inserted into the outer can 8 and the negative electrode 3 was pressure-bonded to the side surface of the outer can 8. The separator 7 was inserted into the hollow part of the negative electrode 3, and the positive electrode with the current collector was inserted into the hollow part of the separator 7. The outer peripheral side surface of the positive electrode 1 and the inner peripheral side surface of the separator 7 face each other, and the outer peripheral side surface of the separator 7 and the inner peripheral side surface of the negative electrode 3 face each other. Then, the above electrolytic solution was injected into the outer can 8, and the electrolytic solution was sufficiently permeated into the electrodes and the like. Next, the insulating gasket 10 was applied to the fitting groove formed in the upper part of the outer can 8 in advance, and the outer can 8 was sealed by caulking the lead terminal-equipped sealing plate on the upper part of the outer can 8. Incidentally, the current collector 2 and the lead terminal 5 are electrically connected by elastic contact.

FIG. 1 shows the inside-out type battery thus produced (outer diameter: 17 mm; height: 33.5 m).
It is a schematic structure sectional drawing of m). This inside-out type battery is referred to as Battery A1 of the invention.

Incidentally, the positive electrode 1 and the negative electrode 3 do not have to have continuous side surfaces. That is, a slit may be provided to improve the circulation of the electrolyte. Further, the positive electrode 1 and the negative electrode 3 may have a bottomed shape.

Example 2 In the production of a positive electrode with a current collector, except that the outer peripheral side surface of the cylindrical current collector 2 is in contact with 80% of the area of the inner peripheral side surface of the cylindrical positive electrode 1. ,
Battery A2 of the invention was produced in the same manner as battery A1 of the invention.

Example 3 In the production of a positive electrode with a current collector, except that the outer peripheral side surface of the cylindrical current collector 2 is in contact with 50% of the area of the inner peripheral side surface of the cylindrical positive electrode 1. ,
Battery A3 of the invention was produced in the same manner as battery A1 of the invention.

[Example 4] In the production of a positive electrode with a current collector, except that the outer peripheral side surface of the cylindrical current collector 2 is in contact with 30% of the area of the inner peripheral side surface of the cylindrical positive electrode 1. ,
A battery A4 of the invention was produced in the same manner as the battery A1 of the invention.

Comparative Example 1 In the production of the positive electrode with a current collector, except that the outer peripheral side surface of the cylindrical current collector 2 is in contact with 5% of the area of the inner peripheral side surface of the cylindrical positive electrode 1. A comparative battery B1 was prepared in the same manner as the battery A1 of the invention.
Although the contact area ratio of the inner peripheral side surface of the positive electrode 1 with the current collector 2 is 5%, this current collector 2 is provided only for electrical connection with the lead terminal 5. That is, this battery assumes a configuration in which the current collector 2 does not exist on the inner peripheral side surface of the positive electrode 1.

[Comparative Example 2] In the production of the separator 7, the battery A1 of the present invention was used except that the polymerized portion 6 of the separator 7 was firmly adhered and the area of the polymerized portion 6 was made to be the minimum necessary for adhesion. Comparative battery B2 was prepared in the same manner.

[Measurement of Discharge Capacity of Battery] The discharge capacities of the batteries (A1 to A4) of the present invention and the comparative batteries (B1 and B2) were measured. The discharge capacity is a constant current of 50 mA,
It is the discharge amount when discharged to the final voltage of 2.5V.

The discharge capacity measurement results are shown in Table 1.

[0035]

[Table 1]

The following can be seen from Table 1.

First, the comparison between the battery A1 of the present invention and the comparative battery B2 will be described.

Comparing the discharge capacities, the battery A1 of the present invention has a larger amount than the comparative battery B2. This means that the battery A1 of the present invention has better reaction efficiency of positive and negative electrodes than the comparative battery B2. It is appropriate to consider that the difference in reaction efficiency between the positive and negative electrodes is caused by the difference in battery configuration.

That is, as the volume of the positive electrode 1 increases in the outer peripheral direction, the overlapping portion 6 of the separator 7 slides and the side surface of the separator 7 expands, so that the volume of the positive electrode 1 that increases due to the discharge of the battery increases to the negative electrode 3 side. That is, the reaction efficiency of the positive and negative electrodes is improved.

Next, the present invention batteries A1 to A4 and the comparative battery B
Reference is made to the comparison with 1.

Comparing the discharge capacities, the batteries A1 to A of the present invention
4 is more than the comparative battery B1. This is the present invention battery A1
It means that the reaction efficiency of the positive and negative electrodes of A4 is better than that of the comparative battery B1. It is appropriate to consider that the difference in the reaction efficiency between the positive and negative electrodes also arises from the difference in the battery configuration.

That is, since the current collector 2 comes into contact with 30% or more of the area of the inner peripheral side surface of the positive electrode 1, the amount of volume increase of the positive electrode 1 is less consumed in the inner peripheral direction.
This means that the volume of the positive electrode 1 increased toward the negative electrode 3 side increased. Incidentally, the same effect was obtained even when the material of the current collector 2 was changed from stainless steel to aluminum.

Finally, the batteries A1 to A4 of the present invention will be mentioned.

Battery A1 of the present invention has a particularly large discharge capacity.
In A2, these discharge capacities are comparative batteries B2 which can be said to be a conventional inside-out type battery of this kind (contact area ratio with the current collector on the inner surface of the positive electrode: 100%; adhesion of the polymerized portion of the separator: Yes) is more than.

Therefore, due to the difference in discharge capacity, the contact area ratio of the inner peripheral side surface of the positive electrode 1 with the current collector 2 is 30 to 100.
% Is desirable, and 80-100% is particularly desirable.

[0046]

When the separator has the overlapped portion on the side surface that slides with the increase in the outer peripheral volume of the positive electrode, the increase in the outer peripheral volume of the positive electrode causes the overlapped portion of the separator to slide and the side surface of the separator expands. The separator does not hinder the increase in the volume of the positive electrode in the outer peripheral direction. Therefore, even if the negative electrode facing the positive electrode decreases due to the discharge of the battery, the volume between the positive electrode and the negative electrode increases due to the increase in the volume due to the discharge of the battery, so that the distance between the positive and negative electrodes can be supplemented. This replenishment improves the reaction efficiency of the positive and negative electrodes. Further, this replenishment also increases the reaction efficiency of the positive and negative electrodes by increasing the reaction area of the positive and negative electrodes.

Further, with this structure, since the compressive force is less likely to act on the separator, it is possible to prevent the separator from being damaged.

When the positive electrode has a substantially tubular shape, the volume of the positive electrode increases when the member that counteracts the increase in the inner peripheral volume of the positive electrode is in contact with 30% or more of the area of the inner peripheral side surface of the positive electrode. Is less consumed in the inner circumferential direction, and the amount of increase in volume of the positive electrode toward the negative electrode is increased.

Therefore, by carrying out the present invention, it is possible to provide an inside-out type battery of this kind in which the reaction efficiency of the positive and negative electrodes is good.

[Brief description of drawings]

FIG. 1 is a schematic structural sectional view of an inside-out type battery according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

1 ... 2 ... Current collector 3 ... Negative electrode 6 ... 7 ... Separator

─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01M 6/16 H01M 2/18

Claims (2)

(57) [Claims] 1. A substantially columnar positive electrode whose volume increases as the battery discharges, a substantially cylindrical negative electrode whose volume decreases as the battery discharges, and
A substantially cylindrical separator that separates the positive electrode and the negative electrode is provided, and the outer peripheral side surface of the positive electrode and the inner peripheral side surface of the separator face each other, and the outer peripheral side surface of the separator and the inner peripheral side surface of the negative electrode face each other. As described above, the negative electrode is located on the outer peripheral side of the positive electrode via the separator, and the separator has a side surface having a polymerized portion that slides due to an increase in the outer peripheral direction volume of the positive electrode. Inside-out type battery. 2. When the positive electrode has a substantially tubular shape, a member that counteracts an increase in the inner circumferential volume of the positive electrode is in contact with 30% or more of the area of the inner circumferential side surface of the positive electrode. The inside-out type battery according to claim 1.