JP2519904Y2 - Flat type non-aqueous electrolyte battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> This invention reduces the reaction area between the positive electrode mixture and the negative electrode by providing a space for holding the electrolytic solution on the outer peripheral side of the positive electrode mixture. The present invention relates to a flat type non-aqueous electrolyte battery, which is devised so as to suppress the increase in the internal resistance of the battery due to the progress of discharge without a problem.

<Prior Art> For example, in a flat type lithium battery, a positive electrode mixture containing manganese dioxide, carbon fluoride, or the like as an active material and a negative electrode containing lithium as an active material are stacked via a separator, and these are connected to a terminal board. And a battery can are combined to be hermetically enclosed in a battery case.

Among these types of batteries, those with a relatively large thickness, such as the CR2450 type and CR2477 type, have the purpose of maintaining the strength of the positive electrode mixture during and after battery assembly to prevent mixture collapse. A structure in which a metallic annular member called an inner battery can is externally fitted around the positive electrode mixture is widely used.

As such a structure, the structure shown in FIGS. 3A and 3B has been proposed.

That is, in the structure of FIG. 3 (A), the positive electrode mixture 11 is fitted inside the battery inner can 13, and this battery inner can 13 is fitted inside the battery can 15 which is an outer can, and the terminal is The insulating gasket 19 attached to the outer peripheral portion of the plate 18 is placed on the flange portion formed on the upper edge of the battery inner can 13, and the opening end portion of the battery can 15 is placed inside with the flange portion as a base. The battery is sealed by crimping and tightening the insulating gasket 19.

In this case, in order to secure a fixed amount of electrolytic solution (amount of electrolytic solution that is more than required for the theoretical capacity of the positive electrode mixture), for example, as shown in the figure, as the positive electrode mixture 11, a hollow portion 11a is formed in the center thereof. A hollow molded article having the above is used, and the hollow portion 11a holds the electrolytic solution. Further, instead of providing such a hollow portion in the positive electrode mixture, a thick separator may be used, that is, a liquid retaining property of the separator may be improved, so that a necessary amount of the electrolytic solution may be retained inside the battery.

On the other hand, in the case of the structure of FIG. 3 (B), contrary to the above-mentioned type, a battery inner can 23 having a flange portion formed on the lower edge is used, and the outer peripheral portion thereof extends to the bottom surface of the battery can. Using the plate 28, an insulating gasket 29 is attached to the outer peripheral portion of the terminal plate 28, and the outer peripheral portion of the inner bottom surface of the battery can 25 is used as a base, and the open end of the battery can 25 is caulked inward to form the insulating gasket 29. The battery is sealed by tightening.

<Problems to be Solved by the Invention> However, in the structure of FIG. 3 (A), in order to hold a necessary and sufficient amount of electrolytic solution, the hollow portion 11 of the positive electrode mixture 11 is held.
It is necessary to increase a to some extent. Therefore, the facing area between the positive electrode mixture 11 and the negative electrode 17 is limited, and the positive electrode mixture 11
Since the outer peripheral portion of the is difficult to react with the negative electrode 17 even through the separator 16, the reaction area contributing to the reaction is small, therefore the utilization ratio of the positive electrode mixture is set to 85% or more of the theoretical capacity practically required. However, there is a problem in that the discharge performance is not uniform.

Further, in this type of non-aqueous electrolyte battery, a reaction occurs in which the positive electrode mixture swells as the discharge progresses, and accordingly, the electrolytic solution permeates the positive electrode mixture and is absorbed. Therefore, in the case of a structure in which the separator is thickened to hold the electrolytic solution as described above, although the electrolytic solution is sufficiently impregnated in the separator at the initial stage of discharging, the electrolytic solution retained in the separator in the latter half of discharging is good. Since the liquid amount tends to be insufficient, the internal resistance of the battery is increased, and as a result, the utilization rate is poor as in the above case.

On the other hand, in the structure of FIG. 3 (B), since the positive electrode mixture and the separator are impregnated with the electrolytic solution and held, the absolute amount of the electrolytic solution tends to be insufficient, and the inner bottom surface of the battery can Because of the sealing structure that tightens the insulating gasket with the outer peripheral part of the base as the base, the effective internal volume in the battery is small,
For example, there is a problem that the absolute capacity of the battery itself is considerably inferior to that of the structure shown in FIG.

This invention has no fear of reducing the reaction area between the positive electrode mixture and the negative electrode, can keep the internal resistance of the battery low even at the end of discharge, and has stable discharge performance with less variation and moreover the discharge capacity. An object is to provide a large flat type non-aqueous electrolyte battery.

<Means for Solving the Problems> In the flat type non-aqueous electrolyte battery of the present invention, an inner battery can having an inwardly bent flange portion at its upper edge is fitted inside the battery can, In addition, a polygonal positive electrode mixture inscribed at four or more locations is arranged inside the battery can, and a separator, a negative electrode, and
Another feature of the present invention is that the terminal plates are sequentially positioned and an insulating gasket provided on the outer peripheral portion of the terminal plate is placed on the flange portion.

Further, in addition to the above structure, a hollow portion is provided in the positive electrode mixture, and the hollow portion communicates with the intermittent space formed between the inner battery can having the flange portion and the positive electrode mixture. May be provided on the bottom surface of the positive electrode mixture.

These hollow portions and grooves may be formed at the same time when the positive electrode mixture is pressure-molded, for example. In addition, for example, a plurality of groove portions may be provided radially from the mixture hollow portion toward the space portion.

Further, in the case of the structure in which the positive electrode current collector is provided between the positive electrode mixture and the bottom surface of the battery can, the same hollow portion and groove may be formed in this positive electrode current collector. In this case, these hollows and grooves may be matched with the hollows and grooves of the positive electrode mixture.

On the other hand, the space portion differs depending on the battery type, but the space portion formed between the battery inner can and the positive electrode mixture, and the positive electrode mixture including the hollow portion and the groove portion of the positive electrode mixture. It may be about 20 to 40% of the total volume. If it is 20% or less, it is difficult to hold a sufficient amount of electrolyte solution on the outer periphery of the mixture, and if it is more than 40%, the storage space of the positive electrode mixture in the battery is reduced to secure the required amount of positive electrode mixture. Can be difficult.

Further, in the present application, the positive electrode mixture is usually a square,
Therefore, the above-mentioned space portion is usually sufficient to have four intermittent arc-shaped spaces formed between the outer periphery of the mixture and the inner can, but if necessary, the shape of the positive electrode mixture may be appropriately changed. Alternatively, it may be a polygonal intermittent space portion.

<Operation> By providing the above space between the positive electrode mixture and the battery can, it becomes possible to hold an amount of the electrolytic solution necessary for the battery reaction in this space, that is, the theory of the positive electrode mixture. Since it is possible to store the electrolytic solution in an amount equal to or more than the capacity required, the increase in the internal resistance at the end of discharge can be effectively suppressed.

Further, since this space portion is provided on the outer peripheral portion of the positive electrode mixture,
In the central portion of the battery, the facing area between the positive electrode mixture and the negative electrode is not limited, and the reaction area between the positive electrode mixture and the negative electrode is not reduced.

Further, since the insulating gasket on the outer peripheral portion of the terminal plate is placed on the flange portion formed on the upper end of the inner can of the battery, the effective internal volume of the battery is large and the discharge capacity is excellent.

On the other hand, by providing the hollow portion and the groove portion as described above, the holding amount of the electrolytic solution can be further increased. For example, when the electrolytic solution is injected from the hollow portion, the electrolytic solution is mixed through the groove portion. Since the electrolyte quickly moves to the outer peripheral space, the electrolytic solution does not fly out together with the air, so that the liquid can be injected smoothly.

<Examples> Examples will be described below.

In FIG. 1 (A), reference numeral 1 is a positive electrode mixture obtained by pressure-molding a mixture of manganese dioxide powder, to which a conductive agent, a binder, and the like are added, into a substantially rectangular shape. A hollow portion 1a having a diameter of about 4 mm is formed in the center of the positive electrode mixture 1, and the bottom surface thereof extends radially outward from the hollow portion 1a as shown in FIG. 1 (B). A plurality of (four in the figure) groove portions 1b having a height of about 0.5 to 1 mm are formed. The total volume including the hollow portion 1a and the groove portion 1b of the positive electrode mixture 1 and the four space portions 4 described below formed on the outer periphery of the mixture is equal to or more than the volume of the negative electrode described below.

The outer periphery of the positive electrode mixture 1 has an inner diameter substantially equal to the outer diameter of the mixture, the outer diameter thereof is substantially equal to the inner diameter of a battery can described later, and the upper edge thereof is bent inward to form a flange. The battery can 3 which is the part 3a is located. Then, as shown in the figure, the positive electrode mixture 1 is fitted inside the battery inner can 3, and the four places on the outer side of the mixture are inscribed in the battery inner can 3, whereby the positive electrode mixture 4 causes the flange portion 3a to move. It will be reinforced. Further, in this fitted state, four arc-shaped discontinuous spaces 4 having a maximum width of about 1 mm are formed between the battery can 3 and the positive electrode mixture 1. In addition, a gap 4a for air bleeding is formed between the inner end of the flange portion 3a of the battery can 3 and the outer peripheral upper end of the positive electrode mixture 1.

The above-described fitting product of the positive electrode mixture 1 and the battery inner can 3 is fitted inside a stainless battery can 5 as shown in FIG. 1 (C). Then, a predetermined amount of non-aqueous electrolyte is injected from the hollow portion 1a of the positive electrode mixture 1. At the time of this injection, the non-aqueous electrolyte is
Immediately spread from the hollow portion 1a through the groove portion 1b to the space portion 4 on the outer periphery of the mixture. Then, the air existing in the space portion 4 and the like is discharged to the outside from the gap 4a, and the electrolyte solution is quickly absorbed on the surface of the mixture facing the hollow portion 1a and the space portion 4 and the like. It can be done smoothly.

After that, the separator 6 is placed on the upper surface of the positive electrode mixture 1,
If a non-aqueous electrolyte is further poured from above the separator 6, lithium or lithium-
A negative electrode 7 using an aluminum alloy or the like as an active material is placed together with a stainless steel terminal plate 8. The separator 6
Is made of polyethylene non-woven fabric, polypropylene non-woven fabric or the like, and has a cup-shaped peripheral portion squeezed to the negative electrode side.

Then, an annular insulating gasket 9 made of synthetic resin such as polyethylene or polypropylene, which is capped on the outer peripheral portion of the terminal plate 8, is placed on the flange portion 3a of the battery can 3 and, in this state, the battery can 5 A coin-type lithium battery of CR2450 (product of the present invention) was produced by crimping the opening of the inside to seal the battery. In addition, in the battery assembly completed state, as shown in the figure, the peripheral portion of the separator 6 is fixed between the peripheral portion of the negative electrode 7 and the inner peripheral portion of the insulating gasket 9.

On the other hand, CR2450 coin-type lithium batteries (comparative products A and B) were prepared in the same manner except that the battery structures were changed to FIGS. 3 (A) and 3 (B), respectively.

Ten of these batteries were made, and the change in voltage when they were continuously discharged at a resistance of 15 KΩ at a temperature of 20 ° C. was examined.

The results are shown in Fig. 2, and it can be seen that the product of the present invention has little variation and the performance is stable, and the discharge capacity is about 10% larger than the comparative products A and B.

In the product of the present invention described above, a hollow portion is provided in the center of the positive electrode mixture, and a groove portion is provided on the bottom side of the positive electrode mixture to connect the hollow portion and the space portion. It is clear that even if the hollow portion and the groove portion are not provided, substantially the same discharge performance is exhibited.

Further, as described above, the positive electrode mixture is fitted into the inside of the battery can, and both are electrically contacted by pressure welding.On the other hand, by caulking the battery can opening at the time of sealing the battery can, In this example, the positive electrode current collector made of a metal plate is pressure-bonded to the lower surface of the positive electrode mixture. It goes without saying that the current collector may be pressure-bonded or spot-welded to the inner surface of the battery can via a conductive paint or the like.

<Effects of the Invention> As described above, according to the present invention, a flat type battery having a large discharge capacity, which does not reduce the reaction area inside the battery, has a low internal resistance even at the end of discharge, and has stable performance. A non-aqueous electrolyte battery can be provided.

Further, when the positive electrode mixture is provided with a hollow portion and a groove portion for communicating the hollow portion and the space portion is provided on the bottom surface of the positive electrode mixture, the amount of electrolyte retained in the battery can be further increased. At the same time, it becomes possible to smoothly inject the electrolytic solution.

[Brief description of drawings]

1 (A) to 1 (C) are explanatory views of the battery of the embodiment, FIG. 2 is a graph showing the discharge performance of the product of the present invention and the conventional product, and FIGS. 3 (A) and 3 (B) are conventional. FIG. 3 is an explanatory view of the battery of FIG. 1,11,21 …… Cathode mixture, 3,13,23 …… Battery can, 5,15,25
…… Battery can, 6,16,26 …… Separator, 7,17,27 …… Negative electrode, 8,18,28 …… Terminal plate, 9,19,29 …… Insulation gasket.

Claims (2)

(57) [Scope of utility model registration request] 1. A polygonal shape in which a battery inner can having an inwardly bent flange portion at its upper edge is fitted inside the battery can, and four or more places are inscribed inside the battery inner can. Of the positive electrode mixture, the separator, the negative electrode, and the terminal plate are sequentially positioned on the positive electrode mixture and the positive electrode inner can, and the insulating gasket provided on the outer peripheral portion of the terminal plate is attached to the flange portion. A flat type non-aqueous electrolyte battery characterized by being placed on top. 2. A hollow portion is provided in the positive electrode mixture,
2. The flat type non-contact surface according to claim 1, wherein a groove portion for communicating the battery can having the hollow portion and the flange portion with the intermittent space portion of the positive electrode mixture is formed on the bottom surface of the positive electrode mixture. Water electrolyte battery.