JP4379633B2 - Sealed battery - Google Patents

Description

The present invention relates to a sealed battery that operates reversibly at an ambient temperature. In particular, the battery has high sealing performance in normal times, and can not only expand and rupture during abnormalities such as overcharge or overdischarge. The present invention relates to a sealed battery that can reduce costs.

In recent years, portable devices for general users have been reduced in size and weight due to great advances in electronic technology. And since the request | requirement of size reduction and weight reduction is increasing also with respect to a battery, the non-aqueous-electrolyte type sealed battery is used abundantly. Generally, a nonaqueous electrolyte-based sealed battery includes a battery body in which a positive electrode and a negative electrode are stacked via an electrolyte layer, a positive electrode terminal and a negative electrode terminal connected to the positive electrode and the negative electrode, respectively, and an open end of the positive electrode terminal. And a sealed battery package that accommodates the battery body so that the open end of the negative electrode terminal is exposed to the outside, and fuses the fusion-bonding resins provided on the inner surface of the sealed battery package together. The battery main body is hermetically sealed by the landing allowance.

The nonaqueous electrolyte type sealed battery has a structure in which the sealed battery package can securely seal the battery body in order to prevent external leakage of the electrolyte or internal entry of moisture, oxygen, etc. Is required. In response to this demand, for example, a solid electrolyte battery (see Patent Document 1: Conventional Example 1) in which a positive electrode terminal and a negative electrode terminal are coated with an ionomer resin, or a coating film of a polyolefin aqueous dispersion is formed on the positive electrode terminal and the negative electrode terminal. A flat battery (see Patent Document 2: Conventional Example 2) has been proposed. According to these conventional examples 1 and 2, it is said that reliable hermeticity can be obtained in the sealed battery package.

By the way, in a nonaqueous electrolyte type sealed battery, if the battery body generates heat when an abnormality such as overcharge or overdischarge occurs, the package for the sealed battery may expand or rupture due to gas generated from the electrolyte. In order to avoid this problem, the applicant of the present application has provided a battery (see Patent Document 3: Conventional Example 3) in which a thin portion is provided at a predetermined portion of the sealed battery package or a predetermined portion of the sealed battery package. A thin battery (see Patent Document 4: Conventional Example 4) with a low peel strength was proposed. According to the conventional example 3 and the conventional example 4, when the internal pressure of the sealed battery package reaches a constant value, an extremely excellent effect is obtained that the hermetic sealing can be surely released to prevent expansion and rupture. It is done.

However, in recent years, a reduction in manufacturing cost has been further demanded for nonaqueous electrolyte based sealed batteries. The present invention has been made in view of the above-mentioned problems, and its purpose is to have high sealing performance in normal times and not only to prevent expansion and rupture during overcharge or overdischarge, but also to reduce the production cost. It is an object of the present invention to provide a sealed battery that can reduce the battery.
JP 60-65442 A Japanese Patent Laid-Open No. 63-232265 JP 9-320550 A Japanese Patent Laid-Open No. 10-55792

In order to achieve the above-described object, the present inventors have intensively studied and have included a lithium salt compound in a part of the fusion resin in the fusion allowance, and the peel strength between the fusion resins is reduced to a lithium salt. It has been found that a desired function can be obtained as an explosion-proof part if it is set lower than other regions not containing a compound. That is, according to the present invention, as described in claim 1, a battery body in which a positive electrode and a negative electrode are stacked via an electrolyte layer, a pair of terminals connected to the positive electrode and the negative electrode, respectively, and a package sealed battery Ru with a fusible resin with open end for accommodating the battery body so as to externally expose, fusion by mutually fusing circumferential portions of the sealed battery package a the sealed battery in which the battery body is hermetically sealed by a Chakudai, the portion of the fusion Chakudai, said fusible resin containing lithium salt compound, packaging the sealed battery is characterized in that the internal pressure of functions as exfoliation possible explosion爆部when it reaches a predetermined value or more.

Some of the fusion Chakudai, realm fusible resin you containing a lithium salt compound can be suitably set, the area is preferably such that communication between the inside and the outside of the package sealed battery .

According to the sealed battery configured as described above, when the internal pressure of the sealed battery package reaches a predetermined value or more due to abnormality such as overcharge or overdischarge, a part of the fusion allowance is melted. The portion of the adhesive resin containing the lithium salt compound is easily peeled off, allowing the inside and outside of the sealed battery package to communicate with each other, thereby reducing the internal pressure of the sealed battery package, thereby providing a sealed battery package. Thus, the same effect as in the prior art can be obtained in which the expansion and rupture of the substrate can be reliably prevented. And in this sealed battery, when assembling the sealed battery, since the explosion-proof part can be installed by a simple operation of containing a lithium salt compound in a part of the fusible resin, the manufacturing cost can be reduced. The above-mentioned purpose can be achieved.

Then, the present inventors have adopted an electrolyte solution by adopting the same lithium salt compound as the electrolyte lithium salt compound contained in the electrolyte solution injected into the battery body as the lithium salt compound contained in the fusible resin. Since it can also be used as a liquid for installing an explosion-proof part, it was found that the explosion-proof part can be installed by an extremely simple operation, and the manufacturing cost of the sealed battery can be greatly reduced. Therefore, the present invention is characterized in that, as described in claim 2, the lithium salt compound is the same lithium salt compound as the electrolyte lithium salt compound contained in the electrolytic solution injected into the battery body. It is said.

Furthermore, the present inventors have made the fusible resin heat-resistant by making the lithium compound contained in the electrolyte injected into the battery body into a fluorinated lithium salt compound and making this electrolyte into a liquid for installing an explosion-proof part. It has been found that a part or all of the fluorine-based lithium salt compound contained in the fusible resin becomes lithium fluoride after fusing and completing a sealed battery. A fluorine-based lithium salt compound is preferable as an electrolyte salt contained in an electrolytic solution because it has excellent safety and good electrical characteristics, and a fluorine-based lithium salt compound on a fusible resin is heat-sealed. The reaction of decomposing and generating lithium fluoride has no problem in assembling the sealed battery. Therefore, since the electrolytic solution containing the fluorine-based lithium salt compound can be used as the liquid for installing the explosion-proof part, the explosion-proof part can be installed by an extremely simple operation, and the manufacturing cost of the sealed battery is reduced. It can be reduced in the same way as a battery. Therefore, according to the present invention, as described in claim 3, the lithium salt compound is a fluorine-based lithium salt compound of the same type as the fluorine-based lithium salt compound contained in the electrolytic solution injected into the battery body and / or Or it is lithium fluoride.

As described above, according to the present invention, as described in claim 1, containing a portion of the fusion Chakudai lithium salt compound fusible resin, the internal pressure of the package for the sealed battery Since it functions as an explosion-proof part that can be peeled off when it reaches a predetermined value or more, it has a high sealing performance in normal times and ensures expansion and rupture in the event of abnormalities such as overcharge or overdischarge. Not only can it be prevented, but an explosion-proof part can be installed by a simple operation of including a lithium salt compound in a part of the fusible resin during assembly, thus providing a sealed battery that can reduce manufacturing costs compared to the conventional case. .

According to the present invention, the lithium salt compound is a lithium salt compound of the same type as the electrolyte lithium salt compound contained in the electrolytic solution. By using a lithium salt compound of the same type as the electrolyte lithium salt compound contained in the electrolytic solution as the salt compound, it is possible to provide a sealed battery that can greatly reduce manufacturing costs.

Hereinafter, embodiments according to the present invention will be described in detail with reference to FIGS. 1 and 2. As shown in FIG. 1, a sealed battery 10 according to an embodiment of the present invention is a small nonaqueous electrolyte secondary battery used for a power source of a portable device, for example, and a battery body 20 having a substantially flat rectangular parallelepiped shape is sealed. The battery package 34 is hermetically sealed.

As shown in FIG. 2, the battery body 20 has a structure in which a positive electrode 25 and a negative electrode 23 are laminated via an electrolyte layer 22, specifically, a positive electrode laminated via a positive electrode current collector 21. 25, a negative electrode 23 that is in close contact with the electrolyte layer 22 that is in close contact with the positive electrode 25, and a negative electrode current collector 24 that is in close contact with the negative electrode 23.

More specifically, the electrolyte layer 22 includes a non-aqueous electrolyte battery separator and an electrolytic solution as main constituent materials. The separator for a nonaqueous electrolyte battery is preferably a fluororesin porous membrane, and among the fluororesins, polyvinylidene fluoride (homopolymer) or a copolymer containing vinylidene fluoride as a repeating unit is desirable. These polyvinylidene fluorides (homopolymers) or copolymers containing vinylidene fluoride as a repeating unit can be obtained by using a known polymerization method such as an emulsion polymerization method or a suspension polymerization method. As the copolymer containing vinylidene fluoride as a repeating unit, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-perfluorovinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, fluoride Vinylidene-trifluoroethylene copolymer, vinylidene fluoride-fluoroethylene copolymer, vinylidene fluoride-hexafluoroacetone copolymer, vinylidene fluoride-ethylene copolymer, vinylidene fluoride-propylene copolymer, fluoride Examples thereof include vinylidene-trifluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, and vinylidene fluoride-ethylene-tetrafluoroethylene copolymer.

The homopolymers or copolymers exemplified above can be used as the material for the porous film either as a single substance or as a mixture. As described above, the porous film preferably contains a fluororesin such as the exemplified homopolymer or copolymer as a main component, but may further contain a polymer other than the fluororesin if necessary. . Examples of the form of the polymer other than the fluororesin include a polymer having a cross-linked site. From the viewpoint of solvent resistance after cross-linking, the weight of the vinylidene fluoride repeating unit in the whole polymer is: It is desirable that the amount is 50% by weight or more based on the total weight of the separator for a nonaqueous electrolyte battery. More desirably, it is 75% by weight or more, and most desirably 95% by weight or more. Further, for the purpose of improving the tensile strength of the electrolyte layer 22, a porous film or a fibrous material made of a resin other than the fluororesin is embedded in or bonded to the porous film made of the fluororesin. A porous film in which a fluororesin and another resin are used in combination can also be used as a separator for a nonaqueous electrolyte battery.

Examples of the material of the porous film and fibrous material other than the fluororesin include polyolefin resins typified by polyethylene and polypropylene, polyester resins typified by polyethylene terephthalate and polybutylene terephthalate, polyphenylene sulfite, polyimide, and glass. desirable. Among these, polyester non-woven fabrics are desirable from the viewpoints of electrolyte impregnation properties, ease of embedding the separator resin, and material costs.

When the non-aqueous electrolyte battery separator is used in combination with the non-woven fabric of the resin as exemplified above together with the fluororesin, the thickness of the non-woven fabric is preferably thin from the viewpoint of energy density. That is, the thickness of the nonwoven fabric is 50 μm or less, desirably 30 μm or less. Furthermore, the basis weight of the nonwoven fabric is preferably 20 g / m ² or less from the viewpoint of the amount of gel-like nonaqueous electrolyte retained. Moreover, 5 g / m < ² > or more is preferable from a viewpoint of the intensity | strength of the separator for nonaqueous electrolyte batteries. For the purpose of improving the tensile strength of the separator for a non-aqueous electrolyte battery, it is possible to use a fluororesin and a non-woven fabric with a graticule arrangement, or a fluororesin and a cloth. The porosity of the non-aqueous electrolyte battery separator is preferably 98% by volume or less from the viewpoint of strength. Further, the porosity is preferably 20% by volume or more from the viewpoint of charge / discharge characteristics.

Next, the electrolyte solution in the electrolyte layer 22 will be described in detail. Examples of the electrolyte salt in the electrolyte solution in the electrolyte layer 22 include LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiSCN, LiBr, LiI, Li ₂ SO ₄ , Li _2. Inorganic ion salts containing one of lithium (Li), sodium (Na), or potassium (K), such as B ₁₀ Cl ₁₀ , NaClO ₄ , NaI, NaSCN, NaBr, KClO ₄ , KSCN, (CH ₃ ) ₄ NBF ₄ , (CH ₃ ) ₄ NBr, (C ₂ H ₅ ) ₄ NClO ₄ , (C ₂ H ₅ ) ₄ NI, (C ₃ H ₇ ) ₄ NBr, (n-C ₄ H ₉ ) ₄ NClO ₄ , _{(n-C 4 H 9)} 4 NI, (C 2 H 5) 4 n-maleate, (C 2 H 5) 4 n-benzoate, (C 2 H ₅ ) Organic ion salts such as quaternary ammonium salts such as ₄ N-phtalate, lithium stearyl sulfonate, lithium octyl sulfonate, and lithium dodecylbenzene sulfonate. Two or more of these ionic compounds may be used in combination. As the electrolyte salt in the electrolytic solution, an electrolyte lithium salt compound containing “lithium (Li)” is preferable among those exemplified above, and more preferably, it has excellent safety and good electrical characteristics can be obtained. It is a fluorine-based lithium salt compound containing both “Li” and “fluorine (F)” such as LiBF ₄ .

Examples of the organic solvent capable of dissolving the ionic compound include cyclic carbonates such as ethylene carbonate, propylene carbonate, and vinylene carbonate; cyclic esters such as γ-butyrolactone; chain esters such as methyl acetate and methyl butyrate; tetrahydrofuran or derivatives thereof. , 1,3-dioxane, 1,2-dimethoxyethane, methyl diglyme and other ethers; acetonitrile, benzonitrile and other nitriles; dioxalane or derivatives thereof; sulfolane, sultone or derivatives thereof alone or in combination of two or more thereof And the like. However, it is not limited to these. Further, the blending ratio and blending method are arbitrary. An electrolytic solution can be obtained by dissolving the ionic compound in such an organic solvent. Among these, high boiling point solvents such as ethylene carbonate, propylene carbonate, and γ-butyrolactone are preferable because of low volatility of the electrolytic solution.

The electrolytic solution exemplified above may be included in advance in an electrolyte part included in at least a part of the separator for a nonaqueous electrolyte battery, the positive electrode 25, and the negative electrode 23. May be. In addition, even in a sealed battery in which the whole battery body in which a separator for a nonaqueous electrolyte battery, a positive electrode, and a negative electrode are stacked is wound, the electrolytic solution is injected into the battery body after the winding. May be. As the injection method, it is possible to inject at normal pressure, but a vacuum impregnation method and a pressure impregnation method can also be used.

Examples of the positive electrode active material used for the positive electrode 25 include group I metal compounds such as CuO, Cu ₂ O, Ag ₂ O, CuS, and CuSO ₄ , group IV metal compounds such as TiS ₂ , SiO ₂ , and SnO, and V ₂ O _5. , V ₆ O ₁₂ , VO _x , Nb ₂ O ₅ , Bi ₂ O ₃ , Sb ₂ O ₃ and other V group metal compounds, CrO ₃ , Cr ₂ O ₃ , MoO ₃ , MoS ₂ , WO ₃ , SeO _2, etc. Group VIII metal compounds such as MnO ₂ and Mn ₂ O ₃ , Group VIII metal compounds such as Fe ₂ O ₃ , FeO, Fe ₃ O ₄ , Ni ₂ O ₃ , NiO, CoO ₃ , and CoO, or the general formula _{Li x MX 2, Li x MN} y X 2 (M, N are metals group VIII from I, X is oxygen, shows a chalcogen compound such as sulfur.) represented by like, for example, lithium -Metal compounds such as cobalt-based composite oxides or lithium-manganese-based composite oxides, and conductive polymer compounds such as disulfide, polypyrrole, polyaniline, polyparaphenylene, polyacetylene, and polyacene materials, and pseudographite-structured carbonaceous materials However, it is not limited to these.

The negative electrode active material used for the negative electrode 23 is modified by adding a carbonaceous material, a metal oxide such as tin oxide or silicon oxide, and adding phosphorus or boron to these materials for the purpose of improving the negative electrode characteristics. The material etc. are mentioned. Of the carbonaceous materials, graphite materials such as carbon are preferable. Below, the analysis result by X-ray diffraction etc. of the carbonaceous material which can be used suitably is shown;
Lattice spacing (d002) 0.333 to 0.360 nm
a-axis direction crystallite size La 20 nm
c-axis crystallite size Lc 20 nm
True density 2.00-2.25 g / cm ³
In addition, a graphite powder obtained by firing an anisotropic pitch at a temperature of 2000 ° C. or more, more preferably, a short fibrous carbon fiber or mesocarbon microbead composed of a graphite material with Lc <100 nm can be used. . However, the lattice spacing, crystallite size, and true density are not limited to the above ranges.

Further, as the negative electrode 23, lithium metal-containing alloys such as lithium metal, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and wood alloy can be used. Is not to be done. In addition, a material in which lithium metal or a lithium metal-containing alloy and an organic compound containing lithium are used in combination, a carbonaceous material in which lithium is inserted by electrochemical reduction of a carbonaceous material, and the like are also used as the negative electrode 23. Is possible.

It is also possible to modify at least the surface layer portion of the positive electrode active material powder and the negative electrode active material powder with a material having good electron conductivity or ion conductivity, or a compound having a hydrophobic group. For example, plating materials with good electron conductivity such as gold, silver, carbon, nickel, copper, materials with good ion conductivity such as lithium carbonate, boron glass, solid electrolyte, or materials having hydrophobic groups such as silicone oil And coating by applying techniques such as sintering, mechanofusion, vapor deposition and baking.

The positive electrode active material powder and the negative electrode active material powder preferably have an average particle size of 100 μm or less. The positive electrode active material powder is desirably 10 μm or less for the purpose of improving the high output characteristics of the sealed battery. In order to obtain the powder in a predetermined shape, a pulverizer or a classifier is used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling air flow type jet mill or a sieve is used. At the time of pulverization, wet pulverization in the presence of water or an organic solvent such as hexane may be used. There is no particular limitation on the classification method, and a sieve, an air classifier, or the like is used as needed for both dry and wet methods.

In addition, about the coating method of the positive electrode 25 and the negative electrode 23, it apply | coats to arbitrary thickness and arbitrary shapes using means, such as roller coating, such as an applicator roll, screen coating, a doctor blade system, spin coating, and a bar coder, for example. However, the present invention is not limited to these. In addition, the real surface area of the positive electrode active material and negative electrode active material which contact the electrolyte layer 22 and an electrical power collector can be increased by using these means.

A conductive agent, a binder, a filler, or the like can be added to the positive electrode 25 and the negative electrode 23 as necessary. The conductive agent is not limited as long as it is an electron conductive material that does not adversely affect the battery performance. Usually, natural graphite (such as scaly graphite, scaly graphite, earthy graphite), artificial graphite, carbon black, acetylene black, Conductive materials such as ketjen black, carbon whisker, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.) powder, metal fiber, and conductive ceramic material can be included as one kind or a mixture thereof. . Among these, as the conductive agent, acetylene black is desirable from the viewpoints of conductivity and coating properties. The addition amount of the conductive agent is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight, based on the total weight of the positive electrode or the negative electrode. These mixing methods are physical mixing, and the ideal is uniform mixing. Therefore, powder mixers such as V-type mixers, S-type mixers, crackers, ball mills, and planetary ball mills can be mixed dry or wet.

As the binder, usually, thermoplastic resins such as tetrafluoroethylene, polyvinylidene fluoride, polyethylene, and polypropylene, ethylene-propylene diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluorine rubber, and the like. A polymer having rubber elasticity, a polysaccharide such as carboxymethylcellulose, and the like can be used as one kind or a mixture of two or more kinds. In addition, it is desirable that a binder having a functional group that reacts with lithium, such as a polysaccharide, be deactivated by, for example, methylation. The addition amount of the binder is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight, based on the total weight of the positive electrode or the negative electrode.

As the filler, any material that does not adversely affect the battery performance may be used. Usually, olefin polymers such as polypropylene and polyethylene, aerosil, zeolite, glass, carbon and the like are used. The addition amount of the filler is preferably 30% by weight or less with respect to the total weight of the positive electrode or the negative electrode.

The positive electrode current collector 21 and the negative electrode current collector 24 may be anything as long as they are electronic conductors that do not adversely affect the constructed battery. For example, as the positive electrode current collector 21, in addition to aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, etc., for the purpose of improving adhesiveness, conductivity and oxidation resistance, The thing which processed the surface, such as aluminum and copper, with carbon, nickel, titanium, silver, etc. can be used. As the negative electrode current collector 24, in addition to copper, nickel, iron, stainless steel, titanium, aluminum, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc., adhesion, conductivity, acid resistance For the purpose of improving the chemical conversion, a material obtained by treating the surface of copper or the like with carbon, nickel, titanium, silver or the like can be used. The surface of these materials can be oxidized.

Regarding the shape of the positive electrode current collector 21 and the negative electrode current collector 24, in addition to the foil shape, a film shape, a sheet shape, a net shape, a punched or expanded material, a lath body, a porous body, a foamed body, and a fiber group A formed body or the like is used. Although there is no particular limitation on the thickness, a thickness of 1 to 500 μm is used. Among these current collectors, an aluminum foil excellent in oxidation resistance is used as a positive electrode, and as a negative electrode, copper foil, nickel foil, iron, which is stable in a reduction field, has excellent conductivity, and is inexpensive. It is preferred to use foils and alloy foils containing parts thereof. Furthermore, a foil having a rough surface surface roughness of 0.2 μmRa or more is preferable, whereby the adhesion between the positive electrode active material or the negative electrode active material and the current collector is excellent. Therefore, it is preferable to use an electrolytic foil because it has such a rough surface. In particular, an electrolytic foil that has been subjected to a cracking treatment is most preferable.

The battery body 20 whose configuration has been described in detail is connected to the open end 26A of the positive terminal 26 and the open end 27A of the negative terminal 27 (see FIG. 1). The positive electrode terminal 26 and the negative electrode terminal 27 are not particularly limited as long as they are conductive materials. Such a battery body 20 is housed in a sealed battery package 34 such that the open end 26A of the positive electrode terminal 26 and the open end 27A of the negative electrode terminal 27 are exposed to the outside.

The sealed battery package 34 includes a metal resin composite film 30 in which a metal foil core material 31, an outer layer 32 along the surface of the metal foil core material 31, and an inner layer 33 along the back surface of the metal foil core material 31 are laminated. Is formed. The metal foil core material 31 is, for example, an aluminum foil, and the layer thickness is set to about 40 μm. The outer layer 32 is, for example, polyethylene terephthalate, and the layer thickness is set to about 10 μm. On the other hand, the inner layer 33 is made of a fusible resin, and specifically, a material having a relatively strong adhesive force to metal such as polyethylene, polypropylene, maleic acid-modified polyethylene, maleic acid-modified polypropylene, etc. It is set to about 30 μm.

In such a sealed battery package 34, two metal resin composite films 30 having a rectangular shape larger than the planar shape of the battery body 20 are prepared, and each metal resin composite film is disposed so that the inner layer 33 faces the battery body 20. 30 is brought into close contact with the negative electrode current collectors 24, 24 of the battery body 20, and then the open end portion 26A of the positive electrode terminal 26 and the open end portion 27A of the negative electrode terminal 27 are exposed to the outside while being exposed to one negative electrode current collector 24. The peripheral portion of the metal resin composite film 30 adhered is bent toward each metal resin composite film 30 in close contact with the other negative electrode current collector 24, and then the peripheral portions of the metal resin composite films 30 are mutually fused. The battery body 20 is hermetically sealed by the fusion allowances 40A, 40B, 40C, and 40D. Here, the width dimensions of the fusion allowances 40A, 40B, 40C, and 40D are set to about 2 mm to 5 mm.

At this time, the fusible resin that is the inner layer 33 of the fusion allowance 40A contains a lithium salt compound before fusion, and the explosion-proof portion 42 is installed by the fusion allowance 40A being fused. That is, the fusible resin that is the inner layer 33 of the fusion allowance 40A has a lower peel strength than the fusible resin that is the inner layer 33 of the other fusion allowances 40B, 40C, and 40D. When the internal pressure of the sealed battery package 34 exceeds a predetermined value due to an abnormality such as charging or overdischarge, the fusion allowance 40A is peeled off prior to the other fusion allowances 40B, 40C, 40D, and the sealed The inside and the outside of the battery package 34 are communicated. As a result, the internal pressure of the sealed battery package 34 decreases, and the expansion and rupture of the sealed battery package 34 can be reliably prevented. In the explosion-proof portion 42, the content of the lithium salt compound of the fusible resin having the fusion allowance 40A is appropriately selected so that the peel strength between the fusible resins containing the lithium salt compound can be set to a desired value. . The peel strength can be measured by a T-type peel method.

Further, in the explosion-proof portion 42, the region of the fusible resin containing the lithium salt compound may be appropriately set according to the limit internal pressure of the sealed battery package 34, but in the present embodiment, It is the entire area of the fusion allowance 40A. As described above, by setting the region where the inner side and the outer side of the sealed battery package 34 communicate with each other, when the internal pressure of the sealed battery package 34 reaches a predetermined value or more, the sealed battery package 34. The inside and outside of the battery can be easily communicated with each other, and the same effect as that of the related art that the expansion and rupture of the sealed battery 10 can be more reliably prevented can be obtained. And in the sealed battery 10, since the explosion-proof part 42 can be installed by the simple operation | work of making the fusion | melting resin of the fusion | melting allowance 40A contain a lithium salt compound, manufacturing cost can be reduced compared with the former.

The lithium salt compound contained in the fusible resin is not particularly limited as long as the object of the present invention can be achieved, but is preferably the same lithium salt compound as the electrolyte lithium salt compound contained in the electrolytic solution. . In this case, since the electrolytic solution can be used as the explosion-proof portion installation liquid, the explosion-proof portion 42 can be installed by an extremely simple operation, and the manufacturing cost of the sealed battery 10 can be further reduced. Examples of the lithium salt compound of the same type as the electrolyte lithium salt compound contained in the electrolyte include the lithium salt compounds that can be used as the exemplified electrolyte.

As a method of incorporating a lithium salt compound into the fusible resin that is the inner layer 33 of the fusion allowance 40A, a method of immersing the fusible resin in a liquid containing the lithium salt compound before fusing the fusible resin Examples thereof include a method of coating or spraying a liquid containing a lithium salt compound on a fusible resin, and any of known dipping methods, coating methods, and spraying methods can be used. An attachment method such as attachment using a liquid dropper containing a lithium salt compound can also be suitably used according to the area of the fusible resin containing the lithium salt compound. Further, when the fusion resin contains a lithium salt compound of the same type as the electrolyte lithium salt compound contained in the electrolyte, the inner layer of the fusion allowance 40A when the electrolyte is poured into the separator for the nonaqueous electrolyte battery Since the explosion-proof part 42 can be installed by moistening 33 with an electrolytic solution and then fusing the inner layer 33 with heat, the manufacturing cost of the sealed battery can be extremely reduced, which is preferable.

The sealed battery according to the present invention is not limited to the above-described embodiment, and appropriate modifications and improvements can be made. That is, in the present invention, for example, the material and shape of the electrolyte layer, the positive electrode, the negative electrode, the battery body, the positive electrode terminal, the negative electrode terminal, the open end, the sealed battery package, the fusible resin, the explosion-proof portion, the metal foil core material, etc. , Dimensions, forms, numbers, locations, etc. are arbitrary and not limited as long as the present invention can be achieved.

EXAMPLES Hereinafter, although the detail of this invention is demonstrated by an Example, this invention is not limited to these. (Example) A sealed battery of Example 1 was produced according to the following procedures (a) to (d). (A) The positive electrode was produced as follows. That is, LiCoO2 as a positive electrode active material, acetylene black as a conductive agent, polyvinylidene fluoride as a binder at a weight ratio of 90: 5: 5, and then a positive electrode slurry of the above material was prepared using N-methylpyrrolidone as a solvent. . The obtained slurry was applied to both sides of a 20 μm aluminum foil as a positive electrode current collector, and N-methylpyrrolidone was removed by drying. This positive electrode plate was pressed by a roll press to obtain a positive electrode.

(B) The negative electrode was produced as follows. That is, a graphite material having a graphite structure of Lc> 100 nm as a negative electrode active material, polyvinylidene fluoride as a binder at a weight ratio of 90:10, and a negative electrode slurry of the above material using N-methylpyrrolidone as a solvent. Produced. The obtained slurry was applied to both surfaces of an electrolytic copper foil having a rough surface roughness of 0.3 μmRa as a negative electrode current collector, and N-methylpyrrolidone was removed by drying. This negative electrode plate was pressed by a roll press to obtain a negative electrode.

(C) The nonaqueous electrolyte battery separator was prepared as follows. That is, a solution obtained by dissolving 12 parts by weight of polyvinylidene fluoride and 8 parts by weight of dibutyl phthalate as a plasticizer in 80 parts by weight of N-methylpyrrolidone as a solvent in a non-woven fabric made of polyethylene terephthalate (thickness 27 μm, basis weight 8 g / m 2). Was embedded on the release paper. Then, it was immersed in 1M lithium hydroxide aqueous solution, solidified, and bridge | crosslinked. Once dried, the excess lithium hydroxide is removed by washing with water, and then carbon dioxide is injected to return to normal pressure (carbonic acid treatment). This is used as a separator for non-aqueous electrolyte batteries. A 70% polyvinylidene fluoride porous membrane was prepared.

(D) Production of sealed battery of examples Positive electrode (A) in close contact with positive electrode current collector obtained in (a) to (c) above, negative electrode (B) in intimate contact with negative electrode current collector, and nonaqueous electrolyte Battery separators were laminated as shown in FIG. 2 to produce a battery body. Subsequently, the aluminum terminal (width 5 mm, thickness 100 μm) (positive electrode terminal) was connected to the positive electrode current collector, and the nickel terminal (width 5 mm, thickness 100 μm) (negative electrode terminal) was connected to the negative electrode current collector by electric resistance welding. did. Next, the outer layer, the metal foil core material, and the inner layer are made of polyethylene terephthalate, aluminum foil, and modified polypropylene, respectively, and the areas other than the area where the explosion-proof part is installed are sealed by heat-sealing, and the explosion-proof part is installed. From the mouth, an electrolytic solution in which 20 parts by weight of lithium tetrafluoroborate, 32 parts by weight of ethylene carbonate, 48 parts by weight of γ-butyrolactone and 32 parts by weight of propylene carbonate were mixed was poured and temporarily vacuum sealed. Finally, it is confirmed that the electrolytic solution is attached to the region of the modified polypropylene where the explosion-proof portion is installed, and the region is sealed by heat sealing, whereby the sealed battery of the embodiment having the configuration shown in FIG. Was made. In the sealed battery of the example, from the fusible resin constituting the explosion-proof portion, lithium tetrafluoroborate (LiBF ₄ ) contained in the electrolytic solution and LiBF ₄ are decomposed by heat fusion. Lithium fluoride (LiF), which was considered to be produced, was confirmed by instrumental analysis and chemical analysis.

(E) Preparation of sealed battery of reference example Except that the electrolytic solution is not attached to the modified polypropylene which is the inner layer of the metal resin composite material, the same procedure as in “(d) Preparation of sealed battery of embodiment” is performed. A sealed battery of a reference example was produced. Device analysis and chemical analysis were performed on the modified polypropylene of the sealed battery of the reference example, but lithium tetrafluoroborate (LiBF ₄ ) and lithium fluoride (LiF) contained in the electrolyte were not confirmed. It was.

(Performance Test of Sealed Battery) A charge / discharge cycle test was conducted at 25 ° C. using the sealed battery of the example and the sealed battery of the reference example. Charging was performed at a constant current and constant voltage of 4.1 V for 7 hours, and discharging was performed at a final voltage of 2.7 V, and a charge / discharge cycle test was performed at a current of 5 hours (0.2 C). The initial discharge capacity and cycle performance are shown in Table 1. The cycle performance indicates the number of cycles at 70% of the initial discharge capacity.

As shown in Table 1, it was confirmed that the sealed battery of the example exhibited excellent charge / discharge cycle characteristics, similar to the sealed battery of the reference example. That is, it was confirmed that the performance of the sealed battery did not deteriorate even when the fusible resin contained a lithium compound as in the sealed battery of the example.

(Overcharge test of sealed battery) Using the sealed battery of the example, an overcharge test of 24 V and 1 CmA was performed after 50 cycles of the cycle test. As a result, gas was released from the explosion-proof portion. Therefore, the explosion-proof function in the sealed battery of the example was confirmed.

As a result, sealed batteries of Examples has a high sealing property at the time of normal, expanded at the time of abnormality of overcharge or the like, yet sealed battery that can prevent explosion, lithium salt in a part of fusible resin Since it was obtained by a simple operation of containing a compound, it was confirmed that it was a sealed battery that could reduce the manufacturing cost.

According to the present invention, as described in claim 3, the lithium salt compound is a fluorine-based lithium salt compound and / or lithium fluoride of the same type as the fluorine-based lithium salt compound contained in the electrolytic solution, Since the electrolyte containing the fluorine-based lithium salt compound can be used as the liquid for installing the explosion-proof part, the explosion-proof part can be installed by an extremely simple operation, and the manufacturing cost of the sealed battery is the same as that of the sealed battery according to claim 2 Can be reduced.

It is a model whole perspective view which shows embodiment which concerns on this invention. It is sectional drawing which shows embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Sealed battery 20 Battery main body 22 Electrolyte layer 23 Negative electrode 25 Positive electrode 26 Positive electrode terminal 27 Negative electrode terminal 26A, 27A Open end part 34 Sealed battery package 40 Fusion allowance 42 Explosion-proof part

Claims (3)

A battery main body in which a positive electrode and a negative electrode are laminated via an electrolyte layer, a pair of terminals connected to the positive electrode and the negative electrode, and the battery main body are accommodated so that open ends of the terminals are exposed to the outside. and a sealed package battery Ru with a fusible resin with the cell body by the peripheral portions of the sealed battery package is mutually fused to be fusion Chakudai is hermetically sealed a sealed battery, wherein the fusion part of Chakudai contains the fusible resin is a lithium salt compound, which can be peeled away when the internal pressure of package the sealed battery reaches or exceeds a predetermined value A sealed battery that functions as an explosion-proof part. 2. The sealed battery according to claim 1, wherein the lithium salt compound is a lithium salt compound of the same type as an electrolyte lithium salt compound contained in an electrolyte solution injected into the battery body. The lithium salt compound is a fluorine-based lithium salt compound and / or lithium fluoride of the same type as the fluorine-based lithium salt compound contained in the electrolyte solution injected into the battery body. Sealed battery.