JP6716631B2 - Non-aqueous battery - Google Patents

Description

The present invention relates to a non-aqueous battery using a battery separator.

Using a laminate film in which a synthetic resin layer is laminated on the surface of a metal layer as an exterior body, an electrode laminate formed by laminating a plurality of positive electrode plates, negative electrode plates and separators is housed inside together with an electrolytic solution to form a flat shape. Aqueous batteries are known.

It is known that the separator constituting the electrode laminate is formed by cutting a microporous resin film made of polyolefin or the like.

JP 2006-287176 A

However, the battery separator has high tensile strength in the unwinding direction (MD direction: Machine Direction), but weak tensile strength in the TD (Transverse Direction) direction (direction perpendicular to the MD direction). That is, when the separator is mechanically cut in the TD direction, its sides are likely to tear.

This means that when the separator is stored in, for example, a battery, its side has low resistance to external force. The separator that is torn by an external force cannot sufficiently serve as an insulator, and the performance as a non-aqueous battery may be reduced.

From the above, it is an object to provide a non-aqueous battery using a battery separator excellent in external force resistance.

The present invention has been devised in view of the above conventional problems, and one aspect thereof is a non-aqueous battery in which a positive electrode plate, a negative electrode plate, and a separator are laminated, and the separator is a microporous resin film. It is cut in a direction parallel to the MD direction and in a direction perpendicular to the MD direction, and is formed into a square or a rectangle having four side portions. A side perpendicular to the MD direction is heated and a side parallel to the MD direction. Is characterized by not being heated.

In a preferred embodiment, the side parallel to the MD direction is formed by mechanical cutting, and the side perpendicular to the MD direction is formed by thermal cutting.

In another preferred aspect, the side parallel to the MD direction is formed by mechanical cutting, and the side perpendicular to the MD direction is heated after cutting.

Further, in a preferred embodiment, heat is applied to the side perpendicular to the MD direction until it becomes transparent.

Furthermore, in a preferred embodiment, a plurality of separators, a positive electrode plate and a negative electrode plate are laminated to form a laminated electrode body as a power generating element, and the electrode laminated body is stored inside an outer casing made of a laminate film. Furthermore, in a preferred embodiment, the positive electrode terminal connected to the positive electrode plate and the negative electrode terminal connected to the negative electrode plate are drawn out from one side of the outer package, and the direction of drawing out the terminals is the same as the MD direction. Characterized by

According to the present invention, in a non-aqueous battery using a battery separator, it becomes possible to facilitate stacking of the battery separator or improve stacking accuracy of the battery separator and improve external force resistance of the battery separator.

It is a perspective view which shows the non-aqueous battery in embodiment. It is sectional drawing which shows the non-aqueous battery in embodiment. It is a schematic sectional drawing which shows the separator in embodiment.

Hereinafter, an embodiment of a non-aqueous battery using a battery separator according to the present invention (hereinafter referred to as a separator) will be described in detail with reference to FIGS. 1 to 3.

In addition, in the following embodiments, the “electrode stack” means a stack of a plurality of positive electrode plates and negative electrode plates.

Further, in the present invention, the "square or rectangular microporous resin film" is not limited to a strictly square or rectangular shape when the microporous resin film is viewed from the thickness direction of the film, The shape of the microporous resin film when viewed from the film thickness direction is approximately square or rectangular, such as when there are convex or concave portions at the ends, if there are dimensional errors, or if there are minute notches. including.

[Embodiment]
First, an example of the non-aqueous battery 1 according to the present invention will be described with reference to FIGS. 1 and 2. The non-aqueous battery 1 is, for example, a lithium ion secondary battery, has a flat rectangular outer shape as shown in FIG. 1, and has a pair of positive electrodes made of a conductive metal foil on one edge in the longitudinal direction. A terminal 2 and a negative electrode terminal 3 are provided.

As shown in FIG. 2, the non-aqueous battery 1 includes an electrode laminate 4 as a rectangular power generating element, which is housed together with an electrolytic solution in an exterior body 5 made of a laminate film. The electrode laminate 4 is composed of a plurality of positive electrode plates 41 and negative electrode plates 42 that are alternately laminated with separators 43 interposed therebetween, and includes, for example, three negative electrode plates 42, two positive electrode plates 41, and a space between them. 4 of the separators 43 are included. That is, in this example, the negative electrode plates 42 are located on both surfaces of the electrode laminate 4. However, a configuration in which the positive electrode plate 41 is located in the outermost layer of the electrode stack 4 is also possible. It should be noted that the dimensions of each part in FIG. 2 are not necessarily accurate, and are exaggerated for the sake of explanation.

The positive electrode plate 41 is formed by forming positive electrode active material layers 41b and 41c on both surfaces of a rectangular positive electrode current collector 41a. The positive electrode current collector 41a is made of an electrochemically stable metal foil such as an aluminum foil, an aluminum alloy foil, a copper foil, or a nickel foil. The positive electrode active material layers 41b and 41c are, for example, a positive electrode active material formed of a lithium composite oxide such as lithium nickel oxide (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), or lithium cobalt oxide (LiCoO ₂ ). And a binder are mixed together and applied to the main surface of the positive electrode current collector 41a.

The negative electrode plate 42 is formed by forming negative electrode active material layers 42b and 42c on both surfaces of a rectangular negative electrode current collector 42a. The negative electrode current collector 42a is made of an electrochemically stable metal foil such as nickel foil, copper foil, stainless steel foil, or iron foil. The negative electrode active material layers 42b and 42c are, for example, amorphous carbon, non-graphitizable carbon, easily graphitizable carbon, or a negative electrode active material that absorbs and releases lithium ions of the above positive electrode active material such as graphite. , A mixture of binders is applied to the main surface of the negative electrode current collector 42a.

A part of the longitudinal edge of the negative electrode current collector 42a extends as an extension 42d that does not include the negative electrode active material layers 42b and 42c, and the tip thereof is joined to the negative electrode terminal 3. Although not shown in FIG. 2, a part of the longitudinal edge of the positive electrode current collector 41a similarly extends as an extension 41d that does not include the positive electrode active material layers 41b and 41c. The tip is joined to the positive electrode terminal 2.

Further, the electrolytic solution is not particularly limited, but as the electrolyte generally used for lithium ion secondary batteries, for example, a non-aqueous electrolytic solution in which a lithium salt is dissolved in an organic solvent can be used. ..

The exterior body 5 that accommodates the electrode laminate 4 having the above-described configuration together with the electrolytic solution is, as shown in a partially enlarged view in FIG. 2, a heat fusion layer 51, a metal layer 52, and a protective layer 53. It is composed of a laminated film having a layered structure. The intermediate metal layer 52 is made of, for example, an aluminum foil, and the heat-sealing layer 51 covering the inner side surface thereof is made of a heat-sealable synthetic resin such as polypropylene (PP), and covers the outer side surface of the metal layer 52. The layer 53 is made of a highly durable synthetic resin such as polyethylene terephthalate (PET). A laminated film having more layers can also be used. Further, in the above example, the synthetic resin layers (the heat-sealing layer 51 and the protective layer 53) are laminated on both sides of the metal layer 52, but the synthetic resin layer (the protective layer 53) outside the metal layer 52 is indispensable. The outer casing 5 may be arranged on the lower surface side of the electrode laminated body 4 of FIG. 2 in one example. One laminated film and one other laminated film arranged on the upper surface side have a two-layer structure, and four sides of these two laminated films are overlapped and heat-sealed to each other. It is composed. The illustrated example shows the exterior body 5 having such a two-layer structure. Further, in another example, the outer casing 5 is made of one relatively large laminated film, and the electrode laminated body 4 is arranged inside in a state of being folded in two, and three peripheral sides are overlapped, In addition, they are heat-sealed to each other.

The pair of positive electrode terminal 2 and negative electrode terminal 3 located on the short side of the rectangular non-aqueous battery 1 are drawn out through the joint surface of the laminate film when the laminate film is heat-sealed.

The procedure for manufacturing the above non-aqueous battery 1 is as follows. First, the negative electrode plate 42, the separator 43, the positive electrode plate 41, and the separator 43 are sequentially laminated, and the positive electrode current collector 41a and the extended portions 41d and 42d of the negative electrode current collector 42a are spot-welded to the positive electrode terminal 2 and the negative electrode terminal 3, respectively. The electrode laminated body 4 is formed by attaching the electrode laminated body 4 and the like. Next, this electrode laminated body 4 is covered with a laminate film to be the outer casing 5, and the peripheral four sides (three sides in the case of the above-mentioned folding in two) are heat-sealed, leaving a relatively small filling port. Next, the electrolytic solution is filled into the exterior body 5 through the filling port, and then the filling port is heat-sealed to bring the exterior body 5 into a sealed state. As a result, the non-aqueous battery 1 is completed.

Here, the separator 43 will be described. The separator 43 has a function of preventing a short circuit between the positive electrode plate 41 and the negative electrode plate 42 and at the same time holding an electrolyte, and is made of, for example, a polyolefin such as polyethylene (PE) or polypropylene (PP). It consists of a microporous resin film. The separator 43 is not limited to a single-layer film of polyolefin or the like, and may have a three-layer structure in which a polypropylene film is sandwiched between polyethylene films, or the like, which dissolves when heat cutting or heat is applied.

The separator 43 according to the present embodiment is cut in parallel with the MD direction at a preset interval to be formed into a strip shape, and then cut at a preset interval in the vertical direction with respect to the MD direction. A rectangular or square separator 43 as shown in 3 is formed.

Here, as shown in FIG. 3, cutting in a direction parallel to the MD direction is mechanical cutting. For this mechanical cutting, for example, a cutter or the like is used. On the other hand, cutting perpendicular to the MD direction is thermal cutting. For example, a laser or the like is used for this thermal cutting, and the temperature is about 170° when the separator 43 is made of polyolefin.

In this way, the side portions 62a and 62b are formed into a straight line by mechanically cutting in the direction parallel to the MD direction. As a result, when the electrode laminated body 4 is laminated, it is possible to perform alignment with the side portions 62a and 62b that have been mechanically cut as a reference, and it is possible to easily laminate the electrode laminated body 4 and the positive electrode and the positive electrode. By improving the stacking accuracy of the negative electrode, it is possible to prevent the capacity of the battery from decreasing due to stacking misalignment.

Further, the cutting in the direction perpendicular to the MD direction is performed by thermal cutting instead of mechanical cutting, so that the side portions 61a and 61b of the separator 43 are melted by heat to close the holes. Therefore, the resistance of the side portions 61a and 61b to the external force is improved, and the damage of the side portions 61a and 61b can be suppressed. As a result, the separator 43 maintains its role as an insulator, and the non-aqueous battery 1 using the separator 43 can suppress the performance deterioration as a battery.

Further, in the case of a winding type non-aqueous battery, the cut side of the separator 43 is generally fastened with a tape, and thus the external force resistance to the cut side is not required. Therefore, when the separator 43 of the present embodiment is used in the non-aqueous battery 1 using the laminated electrode body 4, the effect becomes remarkable.

Further, for example, when the positive electrode terminal 2 is drawn out from the side portion 61a and the negative electrode terminal 3 is drawn out from the side portion 61b in the direction perpendicular to the MD direction, since the electrode laminated body 4 is fixed on both sides, the electrode laminated body is fixed. Movement of body 4 is restricted. However, in the present embodiment, the positive electrode terminal 2 and the negative electrode terminal 3 are drawn out from the side portion 61a in one direction of the side portions 61a and 61b perpendicular to the MD direction. It is fixed only to the exterior body 5 on the side. As a result, the electrode laminated body 4 is restricted in its movement in the side portion 61b direction within the exterior body 5, but is not restricted in its movement in the side portion 61a direction.

Therefore, for example, when an external force is applied from the side portion 61b, the electrode laminated body 4 moves in the outer body 5 toward the side portion 61, the electrode laminated body 4 contacts the positive electrode terminal 2 and the negative electrode terminal 3, and the separator The side part 61a of 43 may be damaged. However, in the present embodiment, the side portion in the direction perpendicular to the stretching direction, particularly 61a, is improved in resistance to external force by being thermally cut, and therefore, the positive electrode terminal 2 and the negative electrode terminal 3 are contacted and damaged. Is suppressed. As a result, the separator 43 can maintain the role of an insulator and suppress the performance deterioration of the non-aqueous battery 1.

Regarding the sides 61a and 61b perpendicular to the MD direction in the embodiment, the method of applying heat at the time of cutting the sides has been described, but the heat may be applied after cutting. Alternatively, the separators 43 may be laminated so that the MD directions are aligned, and heat may be applied by a heater or the like to the side of the electrode laminated body 4 after lamination in the direction perpendicular to the MD direction. Furthermore, before cutting, heat may be applied to a cutting portion of the separator 43 in a direction perpendicular to the MD direction, and the cutting may be performed after the heat is applied. In addition, when heat is applied, it is preferable to perform the heat until the side perpendicular to the MD direction becomes transparent. When heat is applied to the point where it becomes transparent, it melts sufficiently and the resistance to external force improves.

In the above, the present invention has been described in detail only for the specific examples described, but it is obvious to those skilled in the art that various variations and modifications are possible within the scope of the technical idea of the present invention, Of course, such variations and modifications are within the scope of the claims.

DESCRIPTION OF SYMBOLS 1... Non-aqueous battery 2... Positive electrode terminal 3... Negative electrode terminal 4... Laminated electrode body 5... Exterior body 41... Positive electrode plate 42... Negative electrode plate 43... Battery separator 61a, 61b, 62a, 62b... Side part

Claims (1)

A non-aqueous battery having an electrode laminate in which a plurality of positive electrode plates, a plurality of negative electrode plates, and a plurality of separators are laminated,
The plurality of separators are made of a microporous resin film composed of polyolefin, and the separators have a stretching direction that is the same as the MD direction, and are cut in parallel and perpendicular to the MD direction to form four side portions. Is formed in a square or a rectangle having, and a side perpendicular to the stretching direction and the MD direction is formed by applying heat at the time of cutting, and a side parallel to the MD direction is not heated,
The electrode laminate is a state in which the separators are not heat-sealed to each other in any of the four sides, and the positive electrode plates, the negative electrode plates, and the separators are stacked,
The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer, and a part of a longitudinal edge of the positive electrode current collector serves as a positive electrode current collector extension portion that does not include the positive electrode active material layer. The negative electrode plate has a negative electrode current collector and a negative electrode active material layer, and a part of a longitudinal edge of the negative electrode current collector is a negative electrode active material layer. As a negative electrode current collector extension portion that does not include, extending from the negative electrode active material layer in the same direction as the MD direction,
A positive electrode terminal connected to the positive electrode current collector extension and a negative electrode terminal connected to the negative electrode current collector extension are drawn out from one side of the outer package, and the positive electrode current collector, the longitudinal direction of the negative electrode current collector, and The drawing direction of the both terminals is the extending direction and the same direction as the MD direction ,
The non-aqueous battery, wherein the outer package is a laminate film, and the positive electrode terminal and the negative electrode terminal are projected from a side where the laminate films are heat-sealed.

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