JPH07272762A - Nonaqueous electrolytic secondary battery - Google Patents

Abstract

PURPOSE:To prevent the generation of fuming and ignition at overcharge time or at internal short-circuit time and the like, even in the case of forming into a large capacity, by forming a separator of resin containing a solid granular flame retarder. CONSTITUTION:A layered product, laminating positive/negative electrode plates 2, 3 through a separator 8a, is stored in a flat angular battery vessel 10. The separator 8a is formed of resin containing a solid granular flame retarder, and as this resin, polyethylene, polypropylene, etc., are used. When the separator 8a is formed, relating to the resin of polyethylene, polypropylene, etc., 3 to 30wt.% the solid granular flame retarder is mixed, kneaded thereafter rolled, and also drawn, to form a sub mu sized fine porous film of 50mum thickness. Here is set a grain size to 0.05 to 0.3mum in the solid granular flame retarder. Thus in the case of forming into a large capacity, generation of fuming and ignition of the separator 8a, at overcharge time, internal short-circuit time, etc., is eliminated, and safety can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery suitable for use in a large-capacity power supply device used in electric vehicles and the like.

[0002]

2. Description of the Related Art In recent years, a lithium ion secondary battery, which is a non-aqueous electrolyte secondary battery using lithium or a lithium alloy, has been proposed as a secondary battery used in an electric vehicle or the like and capable of achieving a high energy density. . The lithium ion secondary battery will be described with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 10 indicates, for example, a thickness of 300 μm.
The horizontal length of the stainless steel plate is approximately 300m.
m shows a flat rectangular battery container of a sealed type single cell having a vertical length of about 100 mm and a thickness of 30 mm, in which the flat rectangular battery capacity 10 includes 51 positive electrode plates 2 and 52 negative electrodes. A laminated body in which the plates 3 are laminated via the separator 8 is housed.

As the positive electrode plate 2, as shown in FIGS. 1 and 2, a composite oxide of lithium Li and a transition metal such as LiCoO _{2 is} formed on both sides of a current collector 5 made of an aluminum Al foil having a rectangular thickness of about 20 μm. As a positive electrode active material.

As the negative electrode plate 3, as shown in FIGS. 1 and 2, lithium Li is doped on both sides of a current collector 7 made of a copper Cu foil (or nickel Ni foil) having a thickness of about 10 μm and removed. Dopable carbon C, for example, carbon having a graphite structure or carbon such as a non-graphitizable carbon material is deposited as the negative electrode active material 6.

The separator 8 has a rectangular thickness 5
A 0 μm microporous polyethylene film, polypropylene film or the like is used. In this case, as the rectangular size of the positive electrode plate 2, the negative electrode plate 3 and the separator 8, the shape of the separator 8 is maximized as shown in FIG. 1, and the shapes of the positive electrode plate 2 and the negative electrode plate 3 are successively reduced.

Further, an organic electrolytic solution 9 in which LiPF ₆ was dissolved in a mixed solvent of propylene carbonate and diethyl carbonate at a ratio of 1 mol / 1 was injected into the closed flat rectangular battery container 10 to activate the positive electrode. The organic electrolyte 9 is filled between the substance 4 and the negative electrode active material 6. The chemical reaction of this lithium-ion secondary battery is as shown in the following chemical formula 1.

[0008]

[Chemical 1]

Further, tongue pieces 2a and 3a are provided as lead portions on the upper portions of the positive electrode plate 2 and the negative electrode plate 3, respectively, and the tongue piece 2a as the lead portion of the positive electrode plate 2 is provided in the flat rectangular battery container 10. The external positive electrode terminal 1 internally connected to each other and provided at the connection point on the outer upper side wall of the flat rectangular battery container 10.
1 tongue piece 3 as a lead portion of the negative electrode plate 3
a are connected to each other inside the flat rectangular battery container 10,
This connection point is connected to the external negative electrode terminal 12 provided on the external upper side wall of the flat rectangular battery container 10.

In FIG. 1, reference numeral 13 indicates when the internal pressure of the closed flat rectangular battery container 10 becomes higher than a predetermined value.
This is a safety valve that releases the gas inside.

According to such a lithium ion secondary battery, it is possible to obtain, for example, one having an average voltage of 3.5 V and 50 Ah.

[0012]

In the non-aqueous electrolyte secondary battery such as the lithium-ion secondary battery, the one having a small capacity has no problem, but the positive electrode plate 2 of this non-aqueous electrolyte secondary battery. The separator 8 sandwiched between the negative electrode plate 3 and the negative electrode plate 3 is a combustible material such as polyethylene film or polypropylene. For example, the flash point of the polyethylene film is about 350 ° C. and the flash point of polypropylene is about 400 ° C. When the capacity of the liquid secondary battery is increased, there is a problem that smoking or ignition of the separator 8 may occur at the time of overcharging, internal short circuit, or the like.

In view of the above point, the present invention has an object to prevent smoke and ignition from occurring even when the non-aqueous electrolyte secondary battery having a large capacity is overcharged or an internal short circuit occurs.

[0014]

The non-aqueous electrolyte secondary battery of the present invention comprises a positive electrode plate 2 and a negative electrode plate 3 laminated with a separator 8a in between, as shown in FIGS. 1 and 2, for example. In the secondary battery, the separator 8a is formed of a resin containing a solid particulate flame retardant.

In the non-aqueous electrolyte secondary battery of the present invention, the particle size of the solid particulate flame retardant is 0.05 μm in the above description.
m to 0.3 μm.

In the non-aqueous electrolyte secondary battery of the present invention, the solid particulate flame retardant is a halogen-based flame retardant in the above description.

Further, in the above-mentioned non-aqueous electrolyte secondary battery of the present invention, the solid particulate flame retardant is barium sulfate.

[0018]

According to the present invention, since the separator 8a is made of a resin such as polyethylene or polypropylene containing a halogen-based flame retardant and a solid particulate flame retardant such as barium sulfate, the ignition point of the separator 8a is increased. However, neither smoke nor ignition of the separator 8a will occur during overcharge, internal short circuit, or the like.

[0019]

EXAMPLES An example in which the non-aqueous electrolyte secondary battery of the present invention is applied to a lithium ion secondary battery will be described below with reference to the drawings. The lithium-ion secondary battery according to this example has the same configuration as that of FIGS. 1 and 2 except for the configuration of the separator.

That is, as shown in FIG. 1, for example, the thickness is 300 μm.
The horizontal length of the stainless steel plate is about 300 mm,
51 positive electrode plates 2 in a flat rectangular battery container 10 of a sealed single cell having a length of approximately 100 mm and a thickness of 30 mm.
And 52 negative electrode plates 3 are stacked via the separator 8a so as to accommodate a stacked body.

As the positive electrode plate 2, as shown in FIGS. 1 and 2, a composite oxide of lithium Li and a transition metal such as LiCoO _{2 is} formed on both sides of a current collector 5 made of an aluminum Al foil having a rectangular thickness of about 20 μm. As a positive electrode active material.

As the negative electrode plate 3, as shown in FIGS. 1 and 2, lithium Li is doped on both sides of the current collector 7 made of a copper Cu foil (or nickel Ni foil) having a rectangular thickness of about 10 μm and removed. Dopable carbon C, for example, carbon having a graphite structure or carbon such as a non-graphitizable carbon material is deposited as the negative electrode active material 6.

In this example, the separator 8a is made of a resin containing a solid particulate flame retardant.

As the resin, for example, polyethylene, polypropylene or the like similar to the conventional example is used.

As the solid particulate flame retardant, for example, a halogen flame retardant or barium sulfate is used. Examples of this halogen-based flame retardant include bromine-based tetrapromobisphenol A (TBA) and 2,2-bis (4-hydroxy-).
There are 3,5-dipromophenyl) propane and chlorinated chlorinated paraffins. By using antimony trioxide in combination with this halogen-based flame retardant, the flame retarding effect can be further enhanced.

When forming the separator 8a, 3 to 30 parts of resin such as polyethylene or polypropylene is used.
The solid particulate flame retardant in an amount of wt% is mixed and kneaded, and then rolled and stretched to form a sub-μ size microporous film having a thickness of 50 μm.

In this case, the particle diameter of the solid particulate flame retardant is set to 0.
The thickness is set to 05 μm to 0.3 μm. This makes this particle system 0.
This is because when it is less than 05 μm, it becomes difficult to manufacture, and when this particle size is more than 0.3 μm, it tends to come off when stretched to form a film.

The ignition point of the separator 8a made of the resin containing the solid particulate flame retardant is 400 ° C. or higher.

The positive electrode plate 2, the negative electrode plate 3 and the separator 8
As for the rectangular size of a, the shape of the separator 8a is maximized as shown in FIG. 1, and the shapes of the positive electrode plate 2 and the negative electrode plate 3 are successively reduced.

Further, an organic electrolytic solution 9 in which LiPF ₆ was dissolved at a ratio of 1 mol / 1 in a mixed solvent of propylene carbonate and diethylel carbonate was injected into the closed flat rectangular battery container 10, and The organic electrolyte 9 is filled between the positive electrode active material 4 and the negative electrode active material 6. The chemical reaction of this lithium-ion secondary battery is as shown in Chemical Formula 1 above.

Further, tongues 2a and 3a are provided as lead portions on the upper portions of the positive electrode plate 2 and the negative electrode plate 3, respectively, and the tongue piece 2a as the lead portion of the positive electrode plate 2 is provided in the flat rectangular battery container 10. The external positive electrode terminal 1 internally connected to each other and provided at the connection point on the outer upper side wall of the flat rectangular battery container 10.
1 tongue piece 3 as a lead portion of the negative electrode plate 3
a are connected to each other inside the flat rectangular battery container 10,
This connection point is connected to the external negative electrode terminal 12 provided on the external upper side wall of the flat rectangular battery container 10.

According to the lithium ion secondary battery of the present example, it is possible to obtain a battery having an average voltage of 3.5 V and 50 Ah.

Further, according to this embodiment, as the separator 8a, a resin such as polyethylene or polypropylene containing a halogen-based flame retardant and a solid particulate flame retardant such as barium sulfate is used. Without deteriorating the performance, the ignition point of the separator 8a rises to, for example, 400 ° C. or higher, and even a lithium ion secondary battery having a large capacity causes smoke and ignition of the separator 8a during overcharge, internal short circuit, etc. There is a benefit of improving safety without.

Although the present invention has been described with reference to the example in which the present invention is applied to the lithium ion secondary battery, the present invention can be applied to other non-aqueous electrolyte secondary batteries. Further, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0035]

According to the present invention, since the separator 8a is made of a resin such as polyethylene or polypropylene containing a halogen-based flame retardant and a solid particulate flame retardant such as barium sulfate, the non-aqueous electrolyte secondary Without degrading the battery performance, the ignition point of the separator 8a rises to, for example, 400 ° C. or higher, and even when the capacity of the non-aqueous electrolyte secondary battery is increased, the separator 8a emits smoke when overcharged or when an internal short circuit occurs. , There is a benefit of improving safety without causing ignition.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a non-aqueous electrolyte secondary battery.

FIG. 2 is a diagram provided for explaining a lithium ion secondary battery.

[Explanation of symbols]

 2 Positive electrode plate 3 Negative electrode plate 4,6 Active material 5,7 Current collector 8a Separator 9 Electrolyte

Claims (4)

[Claims] 1. A non-aqueous electrolyte secondary battery in which a positive electrode plate and a negative electrode plate are laminated via a separator, wherein the separator is formed of a resin containing a solid particulate flame retardant. Water electrolyte secondary battery. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the solid particulate flame retardant has a particle size of 0.05 μm to
A non-aqueous electrolyte secondary battery having a thickness of 0.3 μm. 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the solid particulate flame retardant is a halogen-based flame retardant. 4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the solid particulate flame retardant is barium sulfate.