JP2008226828A - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of, in a non-aqueous electrolyte battery with a currently further improved high energy density, causing temperature detection to be delayed in rapid temperature rising inside a pole plate group to thereby possibly make the radiation insufficient at the time of over-charge state or the like due to unusual use, malfunction of a protecting circuit, or the like. <P>SOLUTION: The non-aqueous electrolyte battery is provided with a battery case 11 housing therein a pole plate group 27 in which a positive pole plate 14 and a negative pole plate 16, both of which are band-like, are wound through a separator 15, and a sealing member 12 sealing an opening of the battery case 11. A safety protection element 20 operable when sensing the temperature is electrically connected to the non-aqueous electrolyte battery. The safety protection element 20 is configured to contact a heat collection member 21 for heat collection. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a non-aqueous electrolyte secondary battery excellent in safety in which a safety protection element operates effectively.

  In recent years, due to the rapid progress of miniaturization, weight reduction and high performance of portable information devices, the development of non-aqueous electrolyte secondary batteries that have a high operating voltage of 4V as the driving power source and are suitable for high energy density・ Practical application is being carried out.

As the positive electrode active material of the non-aqueous electrolyte secondary battery, lithium-containing transition metal compounds such as LiCoO ₂ having a layered rock salt structure, LiNiO ₂ and LiMn ₂ O ₄ having a spinel structure are used. Employs carbon materials such as natural graphite, spherical and fibrous artificial graphite, non-graphitizable carbon (hard carbon), and graphitizable carbon (soft carbon).

  In order to achieve higher energy density, the positive electrode active material is densely packed, the negative electrode active material with excellent acceptability of the positive electrode active material is adopted, the separator is made thinner, and the mechanical parts are optimized. Efforts are being made.

  However, on the other hand, the recent increase in energy density is that if the battery is overcharged due to abnormal use or malfunction of the protection circuit, etc. It is difficult to achieve both energy density and excellent safety.

  In order to solve such problems, a high thermal conductivity sheet is installed on the electrode plate group of the non-aqueous electrolyte secondary battery to improve the heat dissipation of the electrode plate group, and the high efficiency of the non-aqueous electrolyte secondary battery is improved. A method of improving discharge characteristics by suppressing a temperature rise during discharge is disclosed (for example, see Patent Document 1).

Further, a cylindrical non-aqueous electrolyte solution in which a negative electrode plate and a positive electrode plate made of metallic lithium as an active material are wound in a spiral shape through a separator and a non-aqueous electrolyte solution are enclosed in a container. In the secondary battery, a cylindrical space portion located in the center of the electrode plate group wound with a temperature fuse that detects heat generation in the electrode plate group and interrupts the current in the cylindrical nonaqueous electrolyte secondary battery The charging / discharging current flows immediately through the temperature fuse without any delay in temperature detection even if the internal temperature of the cylindrical non-aqueous electrolyte secondary battery suddenly rises. A method of blocking is disclosed (for example, see Patent Document 2).
Japanese Patent Laid-Open No. 10-40959 Japanese Patent Laid-Open No. 5-266877

  However, in the method of improving the heat dissipation of the electrode plate group by installing a high thermal conductivity sheet on the electrode plate group of the non-aqueous electrolyte secondary battery as in Patent Document 1, the recent further increase in energy density is achieved. If the non-aqueous electrolyte secondary battery is overcharged due to abnormal use or malfunction of the protection circuit, etc., the temperature detection will be delayed due to a sudden rise in temperature inside the electrode plate group, and heat will be dissipated. May become insufficient.

Further, in the method of allowing charge / discharge current to flow through a temperature fuse inserted in a cylindrical space portion existing at the center of the electrode plate group as in Patent Document 2, heat generation in the case of an overcharge state or the like There is a high possibility that the discharge path of the generated gas will be blocked by this thermal fuse, and the space of the electrode plate group will be blocked, and as a result, the internal pressure of the non-aqueous electrolyte secondary battery will be abnormal There was a risk of high.

  The present invention solves the above-described conventional problems, and by contacting a safety protection element that operates by sensing temperature and a heat collecting member that collects heat, the inside of the non-aqueous electrolyte secondary battery is in an abnormal state or the like. The heat generated in is efficiently transmitted to the safety protection element. With this configuration, an object of the present invention is to provide a nonaqueous electrolyte secondary battery in which a safety protection element operates effectively, has a high energy density, and is excellent in safety.

  In order to solve the above problems, the non-aqueous electrolyte secondary battery of the present invention is a battery in which a group of electrode plates formed by winding a belt-like positive electrode plate and a negative electrode plate through a separator and a non-aqueous electrolyte solution are contained therein. A non-aqueous electrolyte secondary battery comprising a case and a sealing body that seals the opening of the battery case and electrically connecting a safety protection element that operates by sensing temperature, A heat collecting member to be heated is brought into contact.

  With this configuration, it is possible to achieve the effect of efficiently transmitting the rapid temperature rise in the non-aqueous electrolyte secondary battery to the safety protection element. Therefore, the safety protection element can quickly and effectively cope with this sudden temperature rise. It operates, and excellent safety can be secured even in a non-aqueous electrolyte secondary battery having a high energy density.

  According to the present invention, a battery in the case of an overcharged state due to abnormal use or malfunction of a protection circuit by contacting a heat collecting member that collects heat with a safety protection element that operates by sensing temperature It is possible to efficiently transmit the sudden temperature rise to the safety protection element, so that the safety protection element operates effectively, and excellent safety is achieved even in non-aqueous electrolyte secondary batteries with high energy density. The effect to ensure is acquired.

  In the present invention, an electrode plate group formed by winding a belt-like positive electrode plate and a negative electrode plate through a separator, a battery case containing a non-aqueous electrolyte therein, and a sealing body that seals the opening of the battery case A non-aqueous electrolyte secondary battery electrically connected to a safety protection element that operates by sensing temperature, and has a configuration in which a heat collecting member that collects heat is in contact with the safety protection element.

  As a result, the heat collecting member that collects the heat generated by the electrode plate group of the non-aqueous electrolyte secondary battery effectively transmits the rapid temperature rise of the battery to the safety protection element, thereby achieving high energy density non-aqueous electrolysis. The effect which can ensure the outstanding safety | security also in a liquid secondary battery is acquired.

  The safety protection element may be disposed on the outer surface of the battery case, and a heat collecting member may be provided so as to cover the safety protection element from the upper surface.

  As a result, the safety protection element and the heat collecting member can be configured in contact with each other after the non-aqueous electrolyte secondary battery is assembled, so that the configuration of the non-aqueous electrolyte secondary battery does not need to be greatly changed and the configuration is relatively easy. The effect that can be obtained.

  Moreover, the said heat collection member can be joined to the outer surface of a battery case, and the said safety protection element can be arrange | positioned from the upper surface.

  Thereby, the effect which can be comprised further easily is acquired.

  The safety protection element may be disposed on the inner surface of the battery case, and a heat collecting member may be provided so as to cover the surface of the safety protection element.

  Thereby, the effect of transmitting the rapid temperature rise of a non-aqueous-electrolyte secondary battery to a safeguard element more efficiently is acquired.

  Further, the safety protection element and the heat collecting member can be provided by being sandwiched between the separator and the positive electrode plate or the negative electrode plate.

  Thereby, since the rapid heat_generation | fever of the electrode group which has a positive electrode plate and a negative electrode plate can be directly transmitted, the effect which further raises the operating precision of a safety protection element is acquired.

  Further, a metal cylindrical heat collecting member can be inserted into the space at the beginning of the electrode plate group, and a safety protection element can be provided on the inner surface of the cylindrical heat collecting member.

  Thereby, since the space in the battery case can be used effectively, it is possible to increase the filling amount of the active material, and an effect that leads to a high capacity of the non-aqueous electrolyte secondary battery can be obtained. Furthermore, the gas generated when the electrode plate group of the non-aqueous electrolyte secondary battery generates heat can be discharged from the lower side to the upper side of the electrode plate group through the metallic cylindrical heat collecting member.

  Moreover, a slit can be provided in the cylindrical heat collecting member.

  This slit provides an effect of ensuring gas permeability even when a safety protection element is arranged in a metal cylindrical heat collecting member.

  Moreover, a safety protection element can be provided in the lower part of the cylindrical heat collecting member provided with the slit.

  If the safety protection element is provided at the lower part of the cylindrical heat collecting member in this way, the gas generated above substantially the center of the electrode plate group is not blocked by the safety protection element. As a result, the effect of smooth gas discharge from the top to the bottom can be obtained.

  Moreover, the said safety protection element can be arrange | positioned on the upper surface or bottom face of a battery case, and this safety protection element can be hold | maintained by the heat collecting member which protrudes from a battery case.

  According to this, the effect which can hold | maintain a safety protection element comparatively easily is acquired.

  Further, the heat collecting member is a negative electrode lead that electrically connects the negative electrode plate and the battery case, and electrically connects the positive electrode plate and the sealing body with the thermal conductivity of the negative electrode lead. It is desirable to make it smaller than the thermal conductivity of the positive electrode lead.

  In this way, if the negative electrode lead is used as a heat collecting member and is made smaller than the thermal conductivity of the positive electrode lead, it may become overcharged due to abnormal use or malfunction of the protective circuit, or non-aqueous electrolyte secondary battery Even if an internal short circuit occurs, the negative electrode lead can be heated first by the current in the battery, and it can be sensed directly by the safety protection element, effectively operating the safety protection element. it can.

  In addition, when the thermal conductivity of the negative electrode lead is 15 to 113 W / (m · K), when a large current instantaneously flows in the battery, such as when the non-aqueous electrolyte secondary battery is internally short-circuited. The negative electrode lead tends to generate heat. There is no problem even during normal use.

  Further, if the material of the negative electrode lead is nickel, it can be suitably used as a heat collecting member having the thermal conductivity. Moreover, when using as a thin flat lead wire, it is easy to comprise in a battery.

  Moreover, even if the material of the negative electrode lead is an iron-nickel alloy, it can be suitably used as a heat collecting member having the thermal conductivity. There is no problem with corrosion resistance. Further, since the mechanical strength and flexibility can be controlled by controlling the nickel content, it can be appropriately adjusted to the size and shape of the battery. In addition to iron and nickel, copper and chromium may be added.

  Further, the material of the negative electrode lead may be a metal obtained by nickel plating on iron. Thus, if it is the metal which plated iron to nickel, a cost effect will be acquired. You may anneal and use the metal which plated nickel with iron. Thus, if it anneals and uses it, since an iron-nickel alloy layer can be formed in the interface of iron and nickel, corrosion resistance can be improved.

  Moreover, it is desirable that the thermal conductivity of the positive electrode lead that electrically connects the positive electrode plate and the sealing body is 236 W / (m · K) or more. If the thermal conductivity of the positive electrode lead is defined in this way, the difference from the thermal conductivity of the negative electrode lead becomes significant, the non-aqueous electrolyte secondary battery is internally short-circuited, and a large current flows instantaneously in the battery. In some cases, heat can be generated concentrated on the negative electrode lead. In addition, if aluminum is used as the material of the positive electrode lead, it can be suitably used as a member having the above thermal conductivity.

  Hereinafter, the nonaqueous electrolyte secondary battery of the present invention will be described with reference to the drawings. FIG. 1 is a partially cutaway perspective view of a prismatic nonaqueous electrolyte secondary battery of the present invention.

  As shown in FIG. 1, a flat electrode plate group 27 in which a positive electrode plate 14 and a negative electrode plate 16 are wound elliptically with a separator 15 therebetween is accommodated in a rectangular battery case 11, and a sealing body 12 is formed. It is electrically connected to the internal terminal. After the sealing body 12 and the battery case 11 are laser welded, a non-aqueous electrolyte is injected from a liquid injection hole provided in the sealing body 12, and then the liquid injection stopper is sealed with a laser to be sealed.

  The heat collecting member 21 continuously covers the widest surface 22 of the battery case 11 and the safety protection element 20. A lead 23 is connected to the safety protection element 20, and one of the leads 23 is electrically connected to an external terminal 29. An insulating tape 25 is attached to the lead 23 connected to the external terminal 29 in order to insulate it from the battery case 11.

  The positive electrode plate 14 is coated with a paste in which a positive electrode active material, a binder and a conductive agent are kneaded and dispersed in a solvent on one side or both sides of a positive electrode current collector 13 made of an aluminum foil, a lathed or etched foil. It is made by wearing, drying and rolling. The thickness of the positive electrode plate 14 is preferably 100 μm to 200 μm and preferably flexible.

As the positive electrode active material, for example, a lithium-containing transition metal compound that can accept lithium ions as a guest is used. For example, a composite metal oxide of at least one metal selected from cobalt, manganese, nickel, chromium, iron, and vanadium and lithium, LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiCo _x Ni _(1-x) O ₂ ( 0 <x <1), LiCrO ₂ , αLiFeO ₂ , LiVO _{2 and the} like are preferable.

The binder is not particularly limited as long as it can be kneaded and dispersed in a dispersion medium. For example, a fluorine binder, acrylic rubber, modified acrylic rubber, styrene-butadiene rubber (SBR), acrylic A polymer, a vinyl polymer or the like can be used alone or as a mixture or copolymer of two or more kinds. As the fluorine-based binder, for example, polyvinylidene fluoride, a copolymer of vinylidene fluoride and propylene hexafluoride, and a dispersion of polytetrafluoroethylene resin are preferable.

  As the conductive agent, acetylene black, graphite, carbon fiber or the like is preferably used alone or as a mixture of two or more kinds, and a thickener can be added as necessary. As the thickener, an ethylene-vinyl alcohol copolymer is used. Carboxymethylcellulose, methylcellulose and the like are preferable.

  As the dispersion medium, a solvent in which the binder can be dissolved is suitable. In the case of an organic binder, N-methyl-2-pyrrolidone, N, N-dimethylformamide, tetrahydrofuran, dimethylacetamide, dimethyl sulfoxide, hexa An organic solvent such as methylsulfuramide, tetramethylurea, acetone or methyl ethyl ketone is preferably used alone or as a mixed solvent thereof. In the case of an aqueous binder, water or warm water is preferred.

  In addition, various dispersants, surfactants, stabilizers, and the like can be added as necessary when the paste is kneaded and dispersed.

  Coating and drying are not particularly limited, and the slurry-like mixture kneaded and dispersed as described above, for example, slit die coater, reverse roll coater, lip coater, blade coater, knife coater, gravure coater, It can be applied easily using a dip coater or the like, and drying close to natural drying is preferred, but considering productivity, it is preferably dried at a temperature range of 70 ° C. to 200 ° C. for 10 minutes to 5 hours.

  Rolling is preferably performed several times at a linear pressure of 1000 to 2000 kg / cm or by changing the linear pressure until a predetermined thickness is reached by a roll press.

  The negative electrode plate 16 is prepared by applying, drying, and rolling a paste obtained by kneading and dispersing a negative electrode active material and a binder, and if necessary, a conductive agent in a solvent, on one side or both sides of the negative electrode current collector 17. be able to. The thickness of the negative electrode plate 16 is 110 to 210 μm, and it is preferable that the negative electrode plate 16 is flexible like the positive electrode plate 14.

  The copper or copper alloy used as the negative electrode current collector 17 is not particularly limited, and examples thereof include rolled foil, electrolytic foil, and the shape thereof is foil, perforated foil, expanded material, lath material, and the like. It does not matter.

As the negative electrode active material, a material containing graphite having a graphite-type crystal structure capable of reversibly inserting and extracting lithium ions, such as natural graphite, spherical and fibrous artificial graphite, non-graphitizable carbon (hard carbon) Carbon materials such as graphitizable carbon (soft carbon) are preferable, and carbon materials having a graphite-type crystal structure in which the lattice spacing ( ₀₀₂ ) spacing (d ₀₀₂ ) is 0.3350 to 0.3400 nm are particularly preferable. More preferably it is used.

  As the binder, the dispersion medium, and the conductive agent and thickener that can be added as necessary, the same materials as those for the positive electrode plate 14 can be used.

  The separator 15 is preferably a single layer of a microporous polyolefin resin such as a polyethylene resin or polypropylene resin having a thickness of 15 to 30 μm or a laminate of polypropylene resin on both sides of the polyethylene resin.

  The battery case 11 includes a cylindrical or square bottomed case with an open upper end, and the material thereof is an aluminum alloy containing a trace amount of metal such as manganese or copper or inexpensive nickel plating from the viewpoint of pressure strength. The steel plate which gave is preferable.

  After the electrode plate group 27, in which the positive electrode plate 14 and the negative electrode plate 16 thus manufactured are wound in a flat shape in a state of being insulated via the separator 15, is dried, the electrode plate group 27 is stored in the battery case 11 or The plate group 27 is stored in the battery case 11 and then dried.

  The drying condition is preferably an atmosphere of low humidity and high temperature. However, if the temperature is too high, the separator 15 may be thermally contracted or the micropores may be crushed, which adversely affects battery characteristics. The dew point is preferably -30 ° C to -80 ° C, and the temperature is preferably 80 ° C to 120 ° C.

  The nonaqueous electrolytic solution is prepared by dissolving an electrolyte in a nonaqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, 1,2-dichloroethane, 1,3-dimethoxypropane, 4- Methyl-2-pentanone, 1,4-dioxane, acetonitrile, propionitrile, butyronitrile, valeronitrile, benzonitrile, sulfolane, 3-methyl-sulfolane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylformamide, dimethylsulfoxide, dimethylformamide, Trimethyl phosphate, triethyl phosphate, and the like can be used, and these nonaqueous solvents can be used alone or as a mixed solvent of two or more kinds.

As the electrolyte contained in the non-aqueous electrolyte, for example, a lithium salt having a strong electron-withdrawing property is used. For example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiC (SO ₂ CF ₃ ) _{3 and the} like. These electrolytes may be used alone or in combination of two or more. These electrolytes are preferably dissolved at a concentration of 0.5 to 1.5M in the non-aqueous solvent.

  The additive that is added to the non-aqueous electrolyte as necessary acts when the non-aqueous electrolyte secondary battery is overcharged, and examples thereof include terphenyl, cyclohexylbenzene, and diphenyl ether. . These additives may be used alone or in combination of two or more. Moreover, it is preferable to add these additives 0.05 to 10weight% with respect to the said non-aqueous electrolyte.

  As the safety protection element 20, there are a temperature return type and a non-reset type. For example, a temperature fuse, a PTC, a thermostat or the like can be used alone or in combination of two or more.

  The heat collecting member 21 is preferably a metal thin film having high thermal conductivity such as aluminum or copper. When using the heat collecting member 21 joined to the battery case 11, a metal plate made of the same material as the battery case 11 may be used.

  Next, a configuration example of the present invention will be described with reference to the drawings.

The non-aqueous electrolyte secondary battery of the present invention is a non-aqueous electrolyte secondary battery in which a safety protection element 20 such as a temperature fuse, PTC, or thermostat that operates by sensing temperature is electrically connected. It can be configured by bringing the protective element 20 into contact with a heat collecting member 21 such as a metal thin film having high thermal conductivity such as aluminum or copper.

  For example, as shown in FIG. 2A, the safety protection element 20 in which the lead 23 is insulated with the insulating tape 25 is disposed on the maximum wide surface 22 on the outer side surface of the battery case 11, and the safety protection element 20 is covered from the upper surface. Thus, the heat collecting member 21 can be attached. The heat collecting member 21 shown in FIG. 2A is a configuration example attached only to the maximum wide surface 22 of the outer side surface of the battery case 11, but as shown in FIG. It may be pasted to cover the entire circumference.

  Further, as shown in FIG. 3, the heat collecting member 21 may be joined to the maximum wide surface 22 of the outer surface of the battery case 11, and the safety protection element 20 may be disposed on the upper surface.

  In addition, as shown in FIG. 4, the safety protection element 20 may be disposed on the inner side surface of the battery case 11, and the heat collecting member 21 may be attached to the upper surface so as to cover the safety protection element 20.

  Further, as shown in FIG. 5, the safety protection element 20 and the heat collecting member 21 may be sandwiched between the separator 15 and the positive electrode plate 14. Similarly, it may be sandwiched between the separator 15 and the negative electrode plate 16.

  Further, as shown in FIG. 6, a cylindrical heat collecting member 21 made of metal such as aluminum or stainless steel is inserted into the space portion 26 at the beginning of rolling of the electrode plate group 27, and this cylindrical heat collecting member 21. It is also possible to configure the safety protection element 20 in contact with the inner surface.

  Moreover, it is preferable to provide the slit 28 in the cylindrical heat collecting member 21 as shown in FIGS.

  If the cylindrical heat collecting member 21 is provided with the slit 28 in this way, the electrode plate group 27 serves to discharge the generated gas through the slit 28 when the internal pressure rises when the electrode plate group 27 generates heat. Even when it is disposed in the space portion 26 at the beginning of the group 27, an effect of securing a discharge path for the generated gas and suppressing an abnormal increase in internal pressure can be obtained.

  It is more preferable to provide the safety protection element 20 at the lower part of the cylindrical heat collecting member 21 provided with the slits 28.

  If the safety protection element 20 is provided in the lower part of the cylindrical heat collecting member 21 in this way, most of the gas generated from the electrode plate group 27 toward the space 26 is generated above the safety protection element 20, Gas emission can be improved.

  Further, as shown in FIGS. 8A to 8C, the heat collecting member 21 may be provided on the upper end portion or the lower end portion of the rectangular battery case 11.

  FIG. 8A is a configuration example in which the heat collecting members 21 are provided opposite to each other at two positions on the upper end portion of the rectangular battery case 11. The two heat collecting members 21 provided on the upper part of the sealing body 12 can be caulked inward to contact and cover the safety protection element 20 to which the lead 23 is connected, and can hold the safety protection element 20. is there.

  FIG. 8B is a configuration example in which a heat collecting member 21 is provided at one place on the upper end of the rectangular battery case 11. The heat collecting member 21 provided on the upper portion of the sealing body 12 can be caulked inward so as to cover the safety protection element 20 to which the lead 23 is connected so as to hold the safety protection element 20.

  FIG. 8C is a configuration example in which the heat collecting members 21 are provided opposite to each other at the two lower end portions of the rectangular battery case 11. The two heat collecting members 21 are caulked inward so as to cover the safety protection element 20 to which the lead 23 is connected so as to hold the safety protection element 20.

  The heat collecting member 21 shown in FIGS. 8A to 8C may be joined to the battery case 11 or a part of the battery case 11 may be protruded.

  In addition, the structure which provides the resin-made exterior material which covers the outer periphery of a nonaqueous electrolyte secondary battery, and clamps the safety protection element 20 and the heat collecting member 21 between this exterior material and the battery case 11 may be sufficient. The material of the exterior material is preferably a PET-based resin from the viewpoint of productivity and environmental protection by heat-shrinking and covering the outer periphery of the battery case 11, and if this contains a nylon-based modifier, the heat-shrinkability is improved and safety is improved. This is suitable for sandwiching the protection element 20 and the heat collecting member 21.

  For example, as shown in FIG. 9, the heat collecting member 21 continuously covers the widest surface 22 of the battery case 11 and the safety protection element 20 to which the lead 23 is connected, and further covers the outer covering 24 so as to cover the outer periphery. It is good to provide. The lead 23 has an insulating tape 25 bonded to an insulating portion.

  As described above, heat generated in the non-aqueous electrolyte secondary battery is efficiently transferred to the safety protection element 20 by bringing the heat collecting member 21 that is a heat conductor such as metal into contact with the safety protection element 20. As compared with the conventional case where the heat collecting member 21 is not provided, the safety protection element 20 can be operated in a state where the temperature of the non-aqueous electrolyte secondary battery is still low.

  As a result, it is possible to stop the overcharge reaction before the positive electrode active material enters an unstable state during overcharge, and to provide a non-aqueous electrolyte secondary battery with high energy density and excellent safety. it can.

  Furthermore, since the amount of the additive acting at the time of overcharging that has been added to the non-aqueous electrolyte in order to maintain safety can be reduced, the effect of improving the battery characteristics in a high temperature environment can also be obtained.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the figure shown here is an example of this invention, and if it has the structure represented to the claim of this invention, the same effect can be acquired.

  The positive electrode plate 14 was prepared by adding 100 parts by weight of lithium cobaltate as a positive electrode active material, 2 parts by weight of acetylene black as a conductive agent, and 3 parts by weight of a polyvinylidene fluoride resin as a binder, and adding N-methyl-2 A paste was prepared by kneading and dispersing pyrrolidone as a solvent. The paste was continuously applied intermittently to a positive electrode current collector 13 made of a strip-shaped aluminum foil having a thickness of 15 μm, dried, and rolled three times at a linear pressure of 1000 kg / cm.

  Next, an aluminum positive electrode lead is ultrasonically welded to the exposed portion of the aluminum foil, and a strip-shaped polypropylene resin insulating tape is provided so as to cover the positive electrode lead in order to prevent a minute short circuit due to a cutting burr of the positive electrode lead. Was attached to prepare a positive electrode plate 14 having a width dimension of 42 mm, a length of 300 mm, and a thickness of 0.145 mm.

The negative electrode plate 16 is 100 parts by weight of scaly graphite capable of occluding and releasing lithium as a negative electrode active material, 1 part by weight of a water-soluble dispersion of styrene butadiene rubber (SBR) as a binder, and a thickener. 1 part by weight of carboxymethyl cellulose and water as a solvent were added and kneaded and dispersed to prepare a paste-like mixture. This paste was continuously intermittently applied to a negative electrode current collector 17 made of a strip-shaped copper foil having a thickness of 10 μm, dried at 110 ° C. for 30 minutes, and rolled three times at a linear pressure of 110 kg / cm.

  Next, a nickel negative electrode lead is resistance-welded to the exposed portion of the copper foil, and a strip-shaped polypropylene resin insulating tape is applied so as to cover the negative electrode lead in order to prevent a minute short circuit similarly to the positive electrode lead. A negative electrode plate 16 having a width dimension of 43 mm, a length of 400 mm, and a thickness of 0.142 mm was produced.

  The positive electrode plate 14 and the negative electrode plate 16 produced in this way were wound in an elliptical shape in a state where they were insulated with a microporous separator 15 made of polyethylene resin having a thickness of 20 μm, thereby constituting an electrode plate group 27. The flat electrode plate group 27 was obtained by pressing from the side surface direction of the electrode plate group 27 at a pressure of 6.5 MPa for 5 seconds.

  The flat electrode plate group 27 is made of a 3000 series aluminum alloy containing a trace amount of metals such as manganese and copper, and has a thickness of 0.25 mm, a width dimension of 6.3 mm, a length dimension of 34.0 mm, and a total height of 50. It was housed in a rectangular battery case 11 produced by press molding of 0.0 mm.

  The moisture content of the electrode plate group 27 was lowered from 500 ppm to 70 ppm as measured with a Karl Fischer moisture meter by drying at a dew point of −30 ° C. and a temperature of 90 ° C. for 2 hours.

After laser-sealing the sealing body 12 and the battery case 11, LiPF ₆ is mixed into a mixed solvent in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed at a ratio of 2: 1 from the injection hole provided in the sealing body 12. Was dissolved at a concentration of 1.0 M, and a nonaqueous electrolyte solution added with 0.5% by weight of cyclohexylbenzene was injected. Then, the injection hole was sealed with a laser and sealed, and the battery capacity was set to 1000 mAh. A square lithium ion secondary battery was produced.

  A thermal fuse is used as the safety protection element 20 of the prismatic lithium ion secondary battery manufactured as described above, and is arranged on the maximum wide surface 22 on the outer surface of the prismatic lithium ion secondary battery as shown in FIG. Then, an aluminum foil with a thickness of 30 μm was brought into contact as the heat collecting member 21 so as to cover the thermal fuse to which the lead 23 was connected from the upper surface.

  At this time, the lead 23 connected below the thermal fuse is brought into contact with the widest surface 22 of the battery case 11, and the insulating tape 25 is bonded to the lead 23 connected above the thermal fuse to insulate the battery case 11. .

  As the shape of the thermal fuse, a thin type having a width of 3.2 mm and a thickness of 0.65 mm was used.

  Then, as shown in FIG. 9, the prismatic lithium ion secondary battery, the thermal fuse, and the prismatic lithium covered with a PET resin exterior material 24 containing a nylon modifier so as to cover the entire aluminum foil. The ion secondary battery was designated as battery A of the present invention.

  A current collecting lead 23 was connected to the prismatic lithium ion secondary battery and the safety protection element 20 so that electricity could flow.

  A prismatic lithium ion secondary battery produced in the same manner as in Example 1 except that the thermal fuse as the safety protection element 20 was covered with a heat collecting member 21 made of aluminum foil having a thickness of 15 μm was designated as battery B of the present invention. .

  A prismatic lithium ion secondary battery produced in the same manner as in Example 1 except that the thermal fuse serving as the safety protection element 20 was covered with a heat collecting member 21 made of copper foil having a thickness of 30 μm was designated as battery C of the present invention. .

  A prismatic lithium ion secondary battery produced in the same manner as in Example 1 except that the thermal fuse as the safety protection element 20 was covered with a heat collecting member 21 made of copper foil having a thickness of 15 μm was designated as battery D of the present invention. .

  As shown in FIG. 2B, a prismatic lithium ion secondary battery manufactured in the same manner as in Example 1 except that the heat collecting member 21 is provided so as to cover almost the entire circumference of the battery case 11 is provided. Battery E.

  As shown in FIG. 3, a copper foil having a thickness of 30 μm was attached as the heat collecting member 21 to the maximum wide surface 22 of the outer side surface of the battery case 11, and a thermal fuse as the safety protection element 20 was brought into contact with the upper surface. Except for the above, a rectangular lithium ion secondary battery produced in the same manner as in Example 1 was designated as Battery F of the present invention.

  As shown in FIG. 4, the same as Example 1 except that the PTC as the safety protection element 20 is provided on the inner side surface of the battery case 11 and covered with the heat collecting member 21 made of aluminum foil having a thickness of 30 μm from the upper surface. The square lithium ion secondary battery produced as described above was designated as battery G of the present invention.

  As shown in FIG. 5, the PTC as the safety protection element 20 is provided on the exposed portion of the positive electrode plate 14 so as to be sandwiched between the heat collecting member 21 made of aluminum foil having a thickness of 15 μm. Except for the above, a rectangular lithium ion secondary battery produced in the same manner as in Example 1 was designated as battery H of the present invention.

  As shown in FIG. 5, the PTC as the safety protection element 20 is provided on the exposed portion of the negative electrode plate 16, and the PTC is provided to be sandwiched between the heat collecting member 21 made of a copper foil having a thickness of 15 μm. Except for the above, a prismatic lithium ion secondary battery produced in the same manner as in Example 1 was designated as Battery I of the present invention.

  As shown in FIG. 8A, an aluminum plate having a thickness of 0.5 mm is welded to the upper end portion of the battery case 11 at two locations as the heat collecting member 21, and between the opposing aluminum plates. A prismatic lithium ion secondary battery produced in the same manner as in Example 1 except that after placing the thermal fuse as the safety protection element 20, the aluminum plate was caulked inward and brought into contact with the thermal fuse. The battery J of the present invention was obtained.

As shown in FIG. 8 (b), a thickness of the battery case 11 having a thickness 0 in which a part of the battery case 1 is projected as the heat collecting member 21 at the upper end of the battery case 11 and the thermal fuse as the safety protection element 20 is projected. A prismatic lithium ion secondary battery produced in the same manner as in Example 1 except that it was caulked so as to be covered with a .25 mm aluminum alloy was designated as battery K of the present invention.

  As shown in FIG. 8 (c), an aluminum plate having a thickness of 0.5 mm is welded to the lower end of the battery case 11 at two locations as the heat collecting member 21, and the safety protection element 20 is interposed between the opposing aluminum plates. A square lithium ion secondary battery manufactured in the same manner as in Example 1 except that the aluminum fuse was caulked inward and contacted with the thermal fuse after placing the thermal fuse as a battery L of the present invention. It was.

(Comparative Example 1)
A corner manufactured in the same manner as in Example 1 except that a thermal fuse as a safety protection element was electrically connected to the external terminal of the prismatic lithium ion secondary battery, and no heat collecting member such as a metal foil was provided. Type lithium ion secondary battery was designated as battery R of Comparative Example.

  A positive electrode plate 14 having a width dimension of 57 mm, a length of 620 mm, and a thickness of 0.180 mm is produced, and a negative electrode board 16 having a width dimension of 59 mm, a length of 645 mm, and a thickness of 0.176 mm is produced, and made of polyethylene resin having a thickness of 20 μm. The electrode group 27 was formed by winding in a substantially circular shape while being insulated via the microporous separator 15. The electrode group 27 is made of nickel-plated steel and is housed in a cylindrical battery case 11 having a thickness of 0.20 mm, an outer diameter of 17.8 mm, and a total height of 64.8 mm, and the sealing body 12 is caulked and sealed. A cylindrical lithium ion secondary battery having a design value of 2100 mAh was obtained in the same manner as in Example 1 except that it was sealed.

  As shown in FIG. 6, a stainless steel cylindrical heat collecting member 21 having a plate thickness of 0.3 mm is inserted into the space 26 at the beginning of the rolling of the electrode plate group 27 of the cylindrical lithium ion secondary battery, A cylindrical lithium ion secondary battery in which a temperature fuse as a safety protection element 20 was provided on the inner side surface of the cylindrical heat collecting member 21 was designated as a battery M of the present invention.

  A small radial lead type was used for the thermal fuse.

  As shown in FIG. 7 (a), a cylindrical lithium ion secondary battery manufactured in the same manner as in Example 13 except that linear slits 28 extending over the upper and lower ends of the cylindrical heat collecting member 21 were provided. Was the battery N of the present invention.

  As shown in FIG. 7 (b), a steel material in which a bent slit 28 is provided between the upper and lower ends of the tubular heat collecting member 21 and nickel plating is applied to the tubular heat collecting member 21 is used. Except for the above, a cylindrical lithium ion secondary battery produced in the same manner as in Example 13 was designated as Battery O of the present invention.

  Cylindrical lithium ion secondary produced in the same manner as in Example 13 except that a slit 28 as shown in FIG. 7C is provided and the cylindrical heat collecting member 21 is made of an aluminum alloy having a thickness of 0.5 mm. The battery was designated as battery P of the present invention.

  Cylindrical lithium ion secondary produced in the same manner as in Example 13 except that a slit 28 as shown in FIG. 7 (d) was provided and the cylindrical heat collecting member 21 was made of an aluminum alloy having a thickness of 0.5 mm. The battery was designated as battery Q of the present invention.

(Comparative Example 2)
A cylindrical lithium ion secondary battery manufactured in the same manner as in Example 13 except that a heat collecting member was not provided after electrically connecting a thermal fuse as a safety protection element to an external terminal of the cylindrical lithium ion secondary battery. The secondary battery was designated as Battery S of Comparative Example.

  For the battery M of Example 13, the negative electrode lead that electrically connects the negative electrode plate 16 and the battery case 11 was used as the heat collection member without using the cylindrical heat collection member. For the negative electrode lead as the heat collecting member, a nickel plate having a plate thickness of 0.15 mm, a width of 4 mm, and a length of 65 mm was used. The thermal conductivity of nickel is 93 W / (m · K) at room temperature. The thermal conductivity of nickel is 83 to 113 W / (m · K) at 100 ° C. to −100 ° C.

  On the other hand, an aluminum plate material having a plate thickness of 0.15 mm, a width dimension of 4.5 mm, and a length dimension of 68 mm was used for the positive electrode lead for electrically connecting the positive electrode plate and the sealing body. The thermal conductivity of this aluminum is 236 W / (m · K) at room temperature. In addition, the heat conductivity of aluminum is 236-241 W / (m * K) in 100 to -100 degreeC.

  A thin type thermal fuse having a width of 2.7 mm and a thickness of 0.64 mm was used as the thermal fuse, and the thermal fuse was attached so as to be attached to the negative electrode lead via a resin film.

  This cylindrical lithium ion secondary battery was designated as battery T of the present invention.

  A cylindrical lithium ion secondary battery produced in the same manner as in Example 18 except that a stainless steel negative electrode lead was used as the heat collecting member was designated as a battery U of the present invention.

  The thermal conductivity of this stainless steel is 15 W / (m · K) at room temperature.

  A cylindrical lithium ion secondary battery produced in the same manner as in Example 18 was used as the battery V of the present invention, except that a negative electrode lead made of an iron-nickel alloy having a nickel content of 78% was used as the heat collecting member. .

  The thermal conductivity of this iron-nickel alloy is 87 W / (m · K) at room temperature.

  A cylindrical lithium ion secondary battery produced in the same manner as in Example 18 was used as the battery W of the present invention, except that a metal negative electrode lead obtained by applying nickel plating to iron was used as the heat collecting member.

  The thermal conductivity of this nickel-plated metal on iron is 81 W / (m · K) at room temperature.

(Reference Example 1)
A cylindrical lithium ion secondary battery produced in the same manner as in Example 18 except that a copper negative electrode lead was used as the heat collecting member was designated as Battery X of Reference Example.

  The copper has a thermal conductivity of 398 W / (m · K) at room temperature. The thermal conductivity of copper is 395 to 420 W / (m · K) at 100 ° C. to −100 ° C.

  Overcharge tests were compared for the above-described prismatic and cylindrical lithium ion secondary batteries A to X.

  The overcharge was evaluated by continuously charging with a charging voltage of 12 V and a charging current of 1000 mA in an environment of 25 ° C., and evaluating the amount of electricity charged until the thermal protection element of the thermal fuse or PTC was activated and the operating temperature of the safety protection element. .

  (Table 1) shows the results of the charged electricity amount, the operating temperature of the safety protection element, and the maximum temperature reached at that time when the cylindrical and prismatic lithium ion secondary batteries were overcharged. The amount of charge is the value when Comparative Example 1 is set to 100 for a prismatic lithium ion secondary battery, and Comparative Example 2 is set to 100 for a cylindrical lithium ion secondary battery.

  As can be seen from (Table 1), the batteries A to Q and the batteries T to W of the present invention in which the heat collecting member 21 is provided and the heat collecting member 21 and the safety protection element 20 are in contact with each other include the heat collecting member 21. It was confirmed that the amount of charged electricity was lower than the batteries R and S of the comparative example that were not provided, and the safety protection element 20 was also operated at a lower temperature.

  This is considered to be because heat generated inside the battery is accurately transmitted to the thermal fuse or PTC as the safety protection element 20 by the heat collecting member 21 due to decomposition of the electrolyte solution or heat generation of the positive electrode active material during overcharge. .

  According to the batteries A to Q of the present invention, it was found that the thicker the heat collecting member 21 and the higher the heat conductivity of the metal foil, the more effective.

  Further, it has been found that the heat collecting member 21 is effective even when included in the exterior material 24. In particular, it has been found that a PET-based resin containing a nylon-based modifier has excellent heat shrinkability and is suitable for sandwiching the safety protection element 20 and the heat collecting member 21.

  According to the batteries T to W of the present invention, it is found that if the heat collecting member is a negative electrode lead and the thermal conductivity of the negative electrode lead is smaller than the thermal conductivity of the positive electrode lead, the thermal fuse operates effectively. It was. This is presumably because when the current flows in the battery, the negative electrode lead having a low thermal conductivity, that is, a high electrical resistance concentrates and generates heat. This effect is particularly useful when a non-aqueous electrolyte secondary battery may be internally short-circuited because a large current that flows instantaneously in the battery can be sensed. Further, it has been found that the fusing of the negative electrode lead due to a large current can be suppressed beforehand by the effective current interruption by the thermal fuse.

  In addition, according to the battery X of Reference Example 1, since the copper having a thermal conductivity larger than the thermal conductivity of aluminum used for the positive electrode lead was used for the negative electrode lead, heat generation was caused when a current flowed in the battery. It is thought that the operation of the thermal fuse was delayed due to the dispersion.

  According to the present invention, it is possible to provide a non-aqueous electrolyte secondary battery with high energy density and excellent safety, which is useful as a power source for portable electronic devices and the like.

Partially cutaway perspective view of a prismatic nonaqueous electrolyte secondary battery of the present invention (A) Schematic perspective view of a prismatic non-aqueous electrolyte secondary battery showing a configuration example of the present invention, (b) Schematic perspective view of a prismatic non-aqueous electrolyte secondary battery showing another configuration example of the present invention. Figure Schematic perspective view of a prismatic nonaqueous electrolyte secondary battery showing another configuration example of the present invention Schematic perspective view of a prismatic nonaqueous electrolyte secondary battery showing another configuration example of the present invention Schematic perspective view of an electrode plate group of a prismatic nonaqueous electrolyte secondary battery showing another configuration example of the present invention Schematic cross-sectional view of a cylindrical nonaqueous electrolyte secondary battery showing another configuration example of the present invention (A) Schematic perspective view of a cylindrical heat collecting member used for the cylindrical nonaqueous electrolyte secondary battery of the present invention, (b) Other cylinder used for the cylindrical nonaqueous electrolyte secondary battery of the present invention The schematic perspective view of a cylindrical heat collecting member, (c) The schematic perspective view of the other cylindrical heat collecting member used for the cylindrical nonaqueous electrolyte secondary battery of the present invention, (d) The cylindrical non-collecting member of the present invention Schematic perspective view of other cylindrical heat collecting member used for water electrolyte secondary battery (A) A schematic perspective view of a prismatic non-aqueous electrolyte secondary battery showing another configuration example of the present invention, (b) A prismatic non-aqueous electrolyte secondary battery showing another configuration example of the present invention. Schematic perspective view, (c) Schematic perspective view of a prismatic non-aqueous electrolyte secondary battery showing another configuration example of the present invention Schematic perspective view of a prismatic nonaqueous electrolyte secondary battery showing another configuration example of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Battery case 12 Sealing body 13 Positive electrode collector 14 Positive electrode plate 15 Separator 16 Negative electrode plate 17 Negative electrode collector 20 Safety protection element 21 Heat collecting member 22 Largest wide surface 23 Lead 24 Exterior material 25 Insulating tape 26 Space part 27 Electrode plate Group 28 Slit 29 External terminal

Claims (11)

An electrode plate group formed by winding a belt-like positive electrode plate and a negative electrode plate with a separator interposed therebetween, a battery case containing a non-aqueous electrolyte, and a sealing body that seals the opening of the battery case A non-aqueous electrolyte secondary battery in which a safety protection element that senses and operates is electrically connected,
A nonaqueous electrolyte secondary battery in which the safety protection element and a heat collecting member for collecting heat are brought into contact with each other.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the safety protection element is disposed on an outer surface of the battery case, and a heat collecting member is provided so as to cover the safety protection element from the upper surface thereof.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the heat collecting member is joined to an outer surface of the battery case, and the safety protection element is disposed on an upper surface thereof.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the safety protection element is disposed on an inner surface of the battery case, and a heat collecting member is provided so as to cover a surface of the safety protection element.   The nonaqueous electrolyte secondary battery according to claim 1, wherein the safety protection element and the heat collecting member are provided so as to be sandwiched between a separator and a positive electrode plate or a negative electrode plate.   The metal plate-shaped heat collecting member is inserted into the space at the beginning of the electrode plate group, and a safety protection element is provided so as to contact the inner side surface of the tubular heat collecting member. The nonaqueous electrolyte secondary battery as described.   The nonaqueous electrolyte secondary battery according to claim 6, wherein a slit is provided in the tubular heat collecting member.   The nonaqueous electrolyte secondary battery according to claim 7, wherein a safety protection element is provided at a lower portion of the cylindrical heat collecting member provided with the slit.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the safety protection element is disposed on an upper surface or a bottom surface of the battery case, and the safety protection element is held by a heat collecting member protruding from the battery case.   The heat collecting member is a negative electrode lead that electrically connects the negative electrode plate and the battery case, and the positive electrode lead that electrically connects the positive electrode plate and the sealing body with the thermal conductivity of the negative electrode lead. The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte secondary battery is smaller than the thermal conductivity.   The negative electrode lead has a thermal conductivity of 15 to 93 W / (m · K) at room temperature, and the positive electrode lead electrically connecting the positive electrode plate and the sealing plate has a thermal conductivity of 236 W / (at room temperature). The nonaqueous electrolyte secondary battery according to claim 10, wherein m · K) or more.

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