JP2008041264A - Battery and short circuit member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery improved in safety when it is crushed by external force and a short circuit member used for the same. <P>SOLUTION: A battery element layering a positive electrode and a negative electrode through a separator and spirally wound, is housed in a battery can. A short circuit member 30 is provided in a gap between the battery can and the battery element. The short circuit member 30 is constructed in such a manner that an insulative intermediate member 33 is arranged between a first conductive member 31 electrically connected to the positive electrode and having a projection part 34 and a second conductive member 32 electrically connected to the negative electrode which face each other. The intermediate member 33 is made thinner in response to the external force applied to the battery can and thus the space between the first conductive member 31 and the second conductive member 32 gets smaller than the height h of the projection part 34. When the external force is applied to the battery to deform the battery can, the projection part 34 penetrates through the intermediate member 33 and sticks in the second conductive member 32, thereby producing short circuit between the positive electrode and the negative electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a battery in which a battery element is accommodated in a battery can and a short-circuit member used in the battery.

  In recent years, many portable electronic devices such as a camera-integrated VTR (video tape recorder), a mobile phone, or a notebook computer have appeared, and their size and weight have been reduced. Batteries used as portable power sources for these electronic devices, particularly secondary batteries, are actively used as key devices for research and development aimed at improving energy density. Among them, non-aqueous electrolyte secondary batteries (for example, lithium ion secondary batteries) can provide a larger energy density than conventional lead batteries and nickel cadmium batteries, which are conventional aqueous electrolyte secondary batteries. Considerations are being made in various directions.

  Lithium ion secondary batteries have been developed in various shapes. For example, a positive electrode and a negative electrode are stacked with a separator between them and wound in a spiral shape, and a metal or resin is wound around the winding center. There is one in which a cylindrical center pin made of a material is inserted (for example, see Patent Document 1 and Patent Document 2).

FIG. 11 shows an example of a conventional center pin. The center pin has a cut 131 in the axial direction of a cylindrical tubular body 130 made of, for example, metal. When an external force is applied to the battery, the main body 130 is crushed, and as a result, the edge of the cut 131 opens to the outside, and the opened portion penetrates the separator to short-circuit between the positive electrode and the negative electrode. As a result, the battery reaction is prevented and the power generation function is safely lost.
Japanese Patent Laid-Open No. 4-332481 JP-A-11-204140

  However, in the secondary battery using the center pin of the above-described conventional structure, there is a problem that deformation at the cut portion when being crushed by an external force is not sufficient, and the positive electrode and the negative electrode cannot be short-circuited reliably. There is a demand for an effective means for ensuring safety by short-circuiting the electrodes more reliably.

  The present invention has been made in view of such problems, and its purpose is to use a battery with improved safety, which can more reliably short-circuit between electrodes when crushed by an external force, and the battery. It is to provide a short-circuit member.

  A battery according to the present invention includes a battery element having a positive electrode and a negative electrode, and a battery can that houses the battery element, the first conductive member electrically connected to the positive electrode, and the negative electrode electrically A short-circuit member disposed opposite to the connected second conductive member with an insulating intermediate member interposed therebetween, and at least one of the first conductive member and the second conductive member has a protrusion on a surface facing the other The intermediate member is configured such that the distance between the first conductive member and the second conductive member is equal to or less than the height of the protruding portion by reducing the thickness according to the external force applied to the battery can.

  The short-circuit member according to the present invention is used for the battery according to the present invention, and the first conductive member electrically connected to the positive electrode and the second conductive member electrically connected to the negative electrode are insulative. The intermediate member is disposed to face the intermediate member, and at least one of the first conductive member and the second conductive member has a protrusion on the surface facing the other, and the intermediate member has a thickness corresponding to an external force applied to the battery can. By reducing the thickness, the distance between the first conductive member and the second conductive member is made equal to or less than the height of the protrusion.

  In the battery according to the present invention or the short-circuit member according to the present invention, the distance between the first conductive member and the second conductive member becomes the height of the protruding portion by reducing the thickness of the intermediate member according to the external force applied to the battery can. Therefore, when a force is applied to the battery from the outside and the battery can is deformed, the protrusion penetrates the intermediate member and pierces the other conductive member, thereby causing a short circuit between the positive electrode and the negative electrode.

  According to the battery of the present invention or the short-circuit member of the present invention, the first conductive member and the second conductive member are arranged to face each other with an insulating intermediate member interposed therebetween, and the intermediate member is formed according to the external force applied to the battery can. Since the distance between the first conductive member and the second conductive member is made smaller than the height of the protrusion by reducing the thickness, the positive electrode The negative electrode can be reliably short-circuited, and safety is improved.

  In particular, when the negative electrode is capable of occluding and releasing electrode reactants and includes a negative electrode active material containing at least one of a metal element and a metalloid element as a constituent element, the energy density of the battery is Since a larger and higher safety is required, a higher effect can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the figure, each component schematically shows the shape, size, and arrangement relationship to the extent that the present invention can be understood, and is different from the actual size.

  1 and 2 show a cross-sectional structure of a secondary battery according to an embodiment of the present invention. This secondary battery is a so-called square type, and has a flat battery element 20 inside a battery can 11 having a substantially hollow rectangular parallelepiped shape.

  The battery can 11 is made of, for example, iron (Fe) plated with nickel (Ni), and also has a function as a negative electrode terminal. The battery can 11 has one end closed and the other end open, and the inside of the battery can 11 is sealed by attaching an insulating plate 12 and a battery lid 13 to the open end. The insulating plate 12 is made of polypropylene or the like, and is disposed on the battery element 20 perpendicular to the winding peripheral surface. The battery lid 13 is made of, for example, the same material as that of the battery can 11 and has a function as a negative electrode terminal together with the battery can 11. A terminal plate 14 serving as a positive electrode terminal is disposed outside the battery lid 13. A through hole is provided near the center of the battery lid 13, and a positive electrode pin 15 electrically connected to the terminal plate 14 is inserted into the through hole. The terminal plate 14 and the battery lid 13 are electrically insulated by an insulating case 16, and the positive electrode pin 15 and the battery lid 13 are electrically insulated by a gasket 17. The insulating case 16 is made of, for example, polybutylene terephthalate. The gasket 17 is made of, for example, an insulating material, and asphalt is applied to the surface.

  A cleavage valve 18 and an electrolyte injection hole 19 are provided near the periphery of the battery lid 13. The cleaving valve 18 is electrically connected to the battery lid 13 and is cleaved when the internal pressure of the battery exceeds a certain level due to an internal short circuit or external heating, thereby suppressing an increase in the internal pressure. . The electrolyte injection hole 19 is closed by a sealing member 19A made of, for example, a stainless steel ball.

  The battery element 20 is formed by laminating a positive electrode 21 and a negative electrode 22 with a separator 23 therebetween and winding them in a spiral shape, and is formed into a flat shape in accordance with the shape of the battery can 11. A positive electrode lead 24 made of aluminum (Al) or the like is connected to the positive electrode 21 of the battery element 20, and a negative electrode lead 25 made of nickel or the like is connected to the negative electrode 22. The positive electrode lead 24 is welded to the lower end of the positive electrode pin 15 to be electrically connected to the terminal plate 14, and the negative electrode lead 25 is welded to and electrically connected to the battery can 11.

  FIG. 3 shows a cross-sectional configuration of the positive electrode 21 shown in FIG. 1 before winding. This positive electrode 21 is obtained by providing a positive electrode active material layer 21B on both surfaces of a strip-shaped positive electrode current collector 21A. Specifically, the positive electrode current collector 21A has a positive electrode covering region 21C where the positive electrode active material layer 21B is present on at least one of the outer peripheral surface side and the inner peripheral surface side. In addition, in the positive electrode 21, the ends on the winding center side and the winding outer peripheral side are exposed without the positive electrode active material layer 21 </ b> B on the positive electrode exposed region 21 </ b> D, that is, on both surfaces of the positive electrode current collector 21 </ b> A. It is an area.

  The positive electrode current collector 21A has, for example, a thickness of about 5 μm to 50 μm and is made of a metal foil such as an aluminum foil, a nickel foil, or a stainless steel foil.

The positive electrode active material layer 21B includes, for example, any one or more of positive electrode materials capable of occluding and releasing lithium, which is an electrode reactant, as a positive electrode active material. A conductive material and a binder such as polyvinylidene fluoride may be included. The positive electrode material capable of inserting and extracting lithium does not contain lithium such as titanium sulfide (TiS ₂ ), molybdenum sulfide (MoS ₂ ), niobium selenide (NbSe ₂ ), or vanadium oxide (V ₂ O ₅ ). Examples thereof include metal sulfides, metal selenides, metal oxides, and lithium-containing compounds containing lithium.

Among these, lithium-containing compounds are preferable because some compounds can obtain a high voltage and a high energy density. Examples of such a lithium-containing compound include a composite oxide containing lithium and a transition metal element, or a phosphate compound containing lithium and a transition metal element. In particular, cobalt (Co), nickel and manganese (Mn Among these, those containing at least one of them are preferred. This is because a higher voltage can be obtained. The chemical formula is represented by, for example, Li _x MIO ₂ or Li _y MIIPO ₄ . In the formula, MI and MII represent one or more transition metal elements. The values of x and y vary depending on the charge / discharge state of the battery, and are generally 0.05 ≦ x ≦ 1.10 and 0.05 ≦ y ≦ 1.10.

Specific examples of the composite oxide containing lithium and a transition metal element include lithium cobalt composite oxide (Li _x CoO ₂ ), lithium nickel composite oxide (Li _x NiO ₂ ), and lithium nickel cobalt having a layered rock salt structure. _Examples thereof include a composite oxide (Li _x Ni _1-z Co _z O ₂ (z <1)) or a lithium manganese composite oxide (LiMn ₂ O ₄ ) having a spinel structure. Among these, a composite oxide containing nickel is preferable. This is because a high capacity can be obtained and excellent cycle characteristics can also be obtained. Specific examples of the phosphate compound containing lithium and a transition metal element include, for example, a lithium iron phosphate compound (LiFePO ₄ ) or a lithium iron manganese phosphate compound (LiFe _1-v Mn _v PO ₄ (v <1)).

  FIG. 4 shows the configuration of the negative electrode 22. The negative electrode 22 is obtained by providing a negative electrode active material layer 22B on both surfaces of a strip-shaped negative electrode current collector 22A. Specifically, the negative electrode covering region 22C where the negative electrode active material layer 22B exists on at least one of the outer peripheral surface side and the inner peripheral surface side of the negative electrode current collector 22A, and the winding center side and the winding outer peripheral side end portions Further, both surfaces of the negative electrode current collector 22A have a negative electrode exposed region 22D that is exposed without the negative electrode active material layer 22B.

  The negative electrode current collector 22A is made of, for example, a metal foil such as a copper foil, a nickel foil, or a stainless steel foil. The thickness of the negative electrode current collector 22A is, for example, 5 μm to 50 μm.

  The negative electrode active material layer 22B includes, for example, a negative electrode active material, and may include other materials such as a conductive material and a binder as necessary. Examples of the negative electrode active material include a negative electrode material that can occlude and release lithium, which is an electrode reactant, and includes at least one of a metal element and a metalloid element as a constituent element. Use of such a negative electrode material is preferable because a high energy density can be obtained. The negative electrode material may be a single element, alloy or compound of a metal element or metalloid element, or may have at least a part of one or more of these phases. In the present invention, alloys include those containing one or more metal elements and one or more metalloid elements in addition to those composed of two or more metal elements. Moreover, the nonmetallic element may be included. There are structures in which a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of them coexist.

  Examples of the metal element or metalloid element constituting the negative electrode material include a metal element or metalloid element capable of forming an alloy with lithium. Specifically, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon, germanium (Ge), tin, lead (Pb), bismuth (Bi), cadmium Examples thereof include (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd), and platinum (Pt).

  Among these, the negative electrode material preferably includes a group 14 metal element or metalloid element in the long-period periodic table as a constituent element, and particularly preferably includes at least one of silicon and tin as a constituent element. This is because silicon and tin have a large ability to occlude and release lithium, and a high energy density can be obtained. Specifically, for example, a simple substance, an alloy, or a compound of silicon, a simple substance, an alloy, or a compound of tin, or a material having one or two or more phases thereof at least in part.

  Examples of tin alloys include silicon, nickel, copper, iron (Fe), cobalt (Co), manganese (Mn), zinc (Zn), indium (In), and silver as second constituent elements other than tin. (Ag), titanium (Ti), germanium (Ge), bismuth (Bi), antimony (Sb), and the thing containing at least 1 sort (s) of chromium (Cr) are mentioned. As an alloy of silicon, for example, as a second constituent element other than silicon, among the group consisting of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony and chromium The thing containing at least 1 sort (s) of these is mentioned.

  Examples of the tin compound or silicon compound include those containing oxygen (O) or carbon (C), and may contain the second constituent element described above in addition to tin or silicon.

  Among these, as this negative electrode material, tin, cobalt, and carbon are included as constituent elements, the carbon content is 9.9 mass% or more and 29.7 mass% or less, and the total of tin and cobalt is A CoSnC-containing material having a cobalt ratio of 30% by mass to 70% by mass is preferable. This is because a high energy density can be obtained in such a composition range, and excellent cycle characteristics can be obtained.

  This CoSnC-containing material may further contain other constituent elements as necessary. Examples of other constituent elements include silicon, iron, nickel, chromium, indium, niobium (Nb), germanium, titanium, molybdenum (Mo), aluminum (Al), phosphorus (P), gallium (Ga), or bismuth. Preferably, 2 or more types may be included. This is because the capacity or cycle characteristics can be further improved.

  This CoSnC-containing material has a phase containing tin, cobalt, and carbon, and this phase preferably has a low crystallinity or an amorphous structure. In this CoSnC-containing material, it is preferable that at least a part of carbon as a constituent element is bonded to a metal element or a semimetal element as another constituent element. The decrease in cycle characteristics is thought to be due to the aggregation or crystallization of tin or the like, but this is because such aggregation or crystallization can be suppressed by combining carbon with other elements. .

  As a measuring method for examining the bonding state of elements, for example, X-ray photoelectron spectroscopy (XPS) can be cited. In XPS, the peak of the carbon 1s orbital (C1s) appears at 284.5 eV in an energy calibrated apparatus so that the peak of the gold atom 4f orbital (Au4f) is obtained at 84.0 eV if it is graphite. . Moreover, if it is surface contamination carbon, it will appear at 284.8 eV. On the other hand, when the charge density of the carbon element increases, for example, when carbon is bonded to a metal element or a metalloid element, the C1s peak appears in a region lower than 284.5 eV. That is, when the peak of the synthetic wave of C1s obtained for the CoSnC-containing material appears in a region lower than 284.5 eV, at least a part of the carbon contained in the CoSnC-containing material is a metal element or a half of other constituent elements. Combined with metal elements.

  In XPS measurement, for example, the C1s peak is used to correct the energy axis of the spectrum. Usually, since surface-contaminated carbon exists on the surface, the C1s peak of the surface-contaminated carbon is set to 284.8 eV, which is used as an energy standard. In the XPS measurement, the waveform of the C1s peak is obtained as a shape including the surface contamination carbon peak and the carbon peak in the CoSnC-containing material. For example, by analyzing using a commercially available software, the surface contamination The carbon peak and the carbon peak in the CoSnC-containing material are separated. In the waveform analysis, the position of the main peak existing on the lowest bound energy side is used as the energy reference (284.8 eV).

  As the negative electrode active material, a carbon material such as natural graphite, artificial graphite, non-graphitizable carbon, or graphitizable carbon may be used. Use of a carbon material is preferable because excellent cycle characteristics can be obtained. Moreover, lithium metal is also mentioned as a negative electrode active material. The negative electrode active material may be used alone or in combination of two or more.

  The separator 23 shown in FIG. 1 is composed of a porous film made of a polyolefin-based material such as polypropylene or polyethylene, or a porous film made of an inorganic material such as a ceramic nonwoven fabric. A structure in which a porous film is laminated may be used.

  The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte. For example, the electrolytic solution includes a solvent and a lithium salt that is an electrolyte salt. The solvent dissolves and dissociates the electrolyte salt. Solvents include propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, and 4-methyl. 1,3 dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, anisole, acetic acid ester, butyric acid ester or propionic acid ester, etc., and any one of these or a mixture of two or more May be.

Examples of the lithium salt include LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, LiCl, or LiBr. One kind or a mixture of two or more kinds may be used.

  Further, in the present embodiment, a conductive short-circuit member 30 is provided in the gap between the battery element 20 and the battery can 11. As shown in FIG. 5, the short-circuit member 30 has a configuration in which a first conductive member 31 and a second conductive member 32 are arranged to face each other with an insulating intermediate member 33 therebetween. The first conductive member 31 is electrically connected to the positive electrode 21 by being joined to the end of the positive electrode current collector 21 </ b> A, and has a protrusion 34 on the surface facing the second conductive member 32. Yes. The second conductive member 32 is electrically connected to the negative electrode 22 by being joined to the battery can 11.

  The intermediate member 33 is configured such that the distance D between the first conductive member 31 and the second conductive member 32 is less than or equal to the height h of the protrusion 34 by reducing the thickness according to the external force applied to the battery can 11. is there. Thereby, in this battery, the positive electrode 21 and the negative electrode 22 can be reliably short-circuited, and safety can be improved.

  In particular, when the negative electrode 22 can occlude and release the electrode reactant and includes a negative electrode active material containing at least one of a metal element and a metalloid element as a constituent element, the energy density of the battery Therefore, a higher effect can be obtained because higher safety is required.

  The first conductive member 31 and the second conductive member 32 are constituted by, for example, a strip-shaped metal plate having a length substantially equal to the height of the battery element 20, and the longitudinal direction thereof is matched with the height direction of the battery element 20. It is arranged. Examples of the constituent material of the first conductive member 31 include aluminum (Al), and examples of the constituent material of the second conductive member 32 include copper (Cu), nickel (Ni), and stainless steel.

  The first conductive member 31 may be provided as a separate member made of the same material as the positive electrode lead 24 or the positive electrode current collector 21A, and the first conductive member 31 itself or a part thereof may be provided as the first conductive member. 31 may also be used. The second conductive member 32 may be provided as a separate member made of the same material as the negative electrode lead 25, the battery can 11, the battery lid 13, or the negative electrode current collector 22A. The portion may also serve as the second conductive member 32.

  The dimensions of the first conductive member 31 and the second conductive member 32 differ depending on the dimensions of the secondary battery. For example, the width W is about 3.0 mm, the length L is 2.5 cm to 8.0 cm, and the thickness T is It is preferable that it is 0.05 mm or more and 5 mm or less. The dimensions of the first conductive member 31 and the second conductive member 32 are not necessarily the same. Here, the “thickness” of the first conductive member 31 and the second conductive member 32 refers to the dimension in the direction in which they are stacked, and the “width” refers to two perpendicular to the thickness direction and perpendicular to each other. The shorter dimension of the direction, the “length” means the longer one.

  The intermediate member 33 is made of, for example, a resin having resistance to an electrolytic solution, and normally maintains a predetermined thickness. On the other hand, when the battery is crushed by an external force, the intermediate member 33 is deformed or crushed according to the external force. In other words, the thickness can be reduced. Specifically, the intermediate member 33 may be made of the same material as the separator 23 such as polyethylene (PE) or polypropylene (PP), or the separator 23 itself or a part thereof may also serve as the intermediate member 33. May be.

  For example, as shown in FIG. 6, the protrusions 34 are preferably provided in the longitudinal direction of the first conductive member 31 as a whole and in one or more rows (for example, three rows in FIG. 6) in the width direction. However, only one column may be used as shown in FIG. The shape of the protrusion 34 may be a cone, or a polygonal pyramid such as a triangular pyramid as shown in FIG. 8 or a quadrangular pyramid as shown in FIG.

  As the dimensions of the protrusions 34, for example, the lower end, that is, the dimension d at the boundary with the first conductive member 31 is preferably 0.1 mm to 3 mm, and the height h is 0.1 mm to 2 mm. The interval p is preferably 0.5 mm to 3 mm, for example. Further, the thickness of the intermediate member 33 at the normal time, that is, the distance D between the first conductive member 31 and the second conductive member 32 is, for example, larger than the height h of the protrusion 34 and three times the height h. It is preferable that it is below a grade.

  For example, the secondary battery can be manufactured as follows.

  First, for example, a positive electrode active material, a conductive agent, and a binder are mixed to prepare a positive electrode mixture, and the positive electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a paste-like material. A positive electrode mixture slurry is obtained. Subsequently, the positive electrode mixture slurry is uniformly applied to the positive electrode current collector 21A using a doctor blade or a bar coater, and the solvent is dried. Then, the positive electrode active material layer 21B is formed by compression molding using a roll press or the like. Then, the positive electrode 21 is produced.

  Next, for example, a negative electrode active material and a binder are mixed to prepare a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent such as N-methyl-2-pyrrolidone to obtain a paste-like negative electrode mixture slurry. And Subsequently, the negative electrode mixture slurry is uniformly applied to the negative electrode current collector 22A using a doctor blade or a bar coater, and the solvent is dried. Then, the negative electrode mixture layer 22B is formed by compression molding using a roll press. Then, the negative electrode 22 is produced. The roll press machine may be used by heating. Moreover, you may compression-mold several times until it becomes the target physical-property value. Furthermore, you may use press machines other than a roll press machine.

  Subsequently, the positive electrode lead 24 is attached to the positive electrode current collector 21A by welding or the like, and the negative electrode lead 25 is attached to the negative electrode current collector 22A by welding or the like. After that, the positive electrode 21 and the negative electrode 22 are stacked with the separator 23 interposed therebetween, wound many times in the winding direction shown in FIGS. 3 and 4, and then formed into a flat shape, thereby producing the battery element 20.

  On the other hand, for example, the first conductive member 31 and the second conductive member 32 made of the above-described material are prepared, and the protrusion 34 is formed on one surface of the first conductive member 31 by a press molding method using a mold having a protrusion shape. Form.

  Next, the surface of the first conductive member 31 on which the protruding portion 34 is formed is opposed to the second conductive member 32, and the intermediate member 33 made of the above-described material is laminated therebetween to form the short-circuit member 30. Subsequently, the short-circuit member 30 is disposed at one of the four corners of the battery can 11, the end of the positive electrode current collector 21 </ b> A is joined to the first conductive member 31 by welding or the like, and the second conductive member 32 is connected to the battery can 11. To be joined by welding.

  After that, the battery element 20 is accommodated in the battery can 11, the insulating plate 12 is disposed on the battery element 20, the negative electrode lead 25 is welded to the battery can 11, and the positive electrode lead 24 is connected to the lower end of the positive electrode pin 15. The battery lid 13 is fixed to the open end of the battery can 11 by laser welding. After that, the electrolytic solution is injected into the inside of the battery can 11 through the electrolytic solution injection hole 19 and impregnated in the separator 23, and then the electrolytic solution injection hole 19 is closed with a sealing member 19A. Thereby, the secondary battery shown in FIGS. 1 and 2 is completed.

  In the secondary battery, when charged, for example, lithium ions are extracted from the positive electrode 21 and inserted in the negative electrode 22 through the electrolytic solution impregnated in the separator 23. When the discharge is performed, for example, lithium ions are released from the negative electrode 22 and inserted into the positive electrode 21 through the electrolytic solution impregnated in the separator 23. In this secondary battery, the short-circuit member 30 in which the first conductive member 31 and the second conductive member 32 having the protrusions 34 are disposed to face each other with the intermediate member 33 interposed therebetween is provided. Since the distance between the first conductive member 31 and the second conductive member 32 becomes equal to or less than the height h of the protrusion 34 by reducing the thickness according to the external force applied to the battery can 11, When force is applied and the battery can 11 is deformed, the intermediate member 33 is also crushed and thinned, and the projection 34 penetrates the intermediate member 33 to the second conductive member 32 as shown in FIG. I bite and pierce. Thereby, the positive electrode 21 and the negative electrode 22 are short-circuited reliably.

  Further, in this secondary battery, a short circuit between the positive electrode 21 and the negative electrode 22 occurs in the short circuit member 30, and no short circuit occurs via the positive electrode active material layer 21B having a high resistance value. Temperature rise is suppressed and safety is further improved. Further, the positive electrode exposed region 21D and the negative electrode exposed region 22D on the winding outer periphery side can be reduced, and the capacity is improved accordingly.

  As described above, in the present embodiment, the short-circuit member 30 in which the first conductive member 31 and the second conductive member 32 having the protrusions 34 are disposed to face each other with the intermediate member 33 interposed therebetween is provided. Since the distance between the first conductive member 31 and the second conductive member 32 is made equal to or less than the height h of the protrusion 34 by thinning in accordance with the external force applied to the battery can 11, the external force is applied to the battery When the can 11 is deformed, the projecting portion 34 pierces the second conductive member 32, and the positive electrode 21 and the negative electrode 22 can be reliably short-circuited. In particular, it is suitable for a prismatic battery in which a cylindrical center pin cannot be used or a large battery with a large calorific value, and high safety can be obtained.

  Moreover, since the short circuit between the positive electrode 21 and the negative electrode 22 can be caused in the short-circuit member 30, there is no short-circuit through the positive electrode active material layer 21B having a high resistance value, and the short circuit member 30 rises in the positive electrode active material layer 21B. Temperature can be suppressed and safety can be further improved. Further, the positive electrode exposed region 21D and the negative electrode exposed region 22D on the winding outer periphery side can be reduced, and the capacity can be increased accordingly.

  In particular, when the negative electrode 22 is capable of inserting and extracting an electrode reactant and includes a negative electrode active material containing at least one of a metal element and a metalloid element as a constituent element, the battery Since the energy density is high and higher safety is required, higher effects can be obtained.

  Further, specific embodiments of the present invention will be described in detail.

(Examples 1-4)
The secondary battery described in the first embodiment was manufactured. First, lithium carbonate (Li ₂ CO ₃ ) and cobalt carbonate (CoCO ₃ ) are mixed at a ratio of Li ₂ CO ₃ : CoCO ₃ = 0.5: 1 (molar ratio), and 5 ° C. at 900 ° C. in the air. After firing for a time, lithium-cobalt composite oxide (LiCoO ₂ ) as a positive electrode active material was obtained. Next, 91 parts by mass of this lithium / cobalt composite oxide, 6 parts by mass of graphite as a conductive agent, and 3 parts by mass of polyvinylidene fluoride as a binder were mixed to prepare a positive electrode mixture. Subsequently, this positive electrode mixture is dispersed in N-methyl-2-pyrrolidone as a solvent to form a positive electrode mixture slurry, which is uniformly applied to both surfaces of a positive electrode current collector 21A made of an aluminum foil having a thickness of 20 μm and dried. Then, the positive electrode active material layer 21B was formed by compression molding with a roll press machine, and the positive electrode 21 was produced. Subsequently, a positive electrode lead 24 made of aluminum was attached to one end of the positive electrode current collector 21A.

  In addition, a CoSnC-containing material was produced as a negative electrode active material. First, cobalt powder, tin powder, and carbon powder were prepared as raw materials, and cobalt powder and tin powder were alloyed to produce a cobalt-tin alloy powder. Then, carbon powder was added to the alloy powder and dry mixed. Subsequently, this mixture was synthesized using a mechanochemical reaction using a planetary ball mill to obtain a CoSnC-containing material.

  When the composition of the obtained CoSnC-containing material was analyzed, the cobalt content was 29.3 mass%, the tin content was 49.9 mass%, and the carbon content was 19.8 mass%. . The carbon content was measured by a carbon / sulfur analyzer, and the cobalt and tin contents were measured by ICP (Inductively Coupled Plasma) emission analysis. Further, when X-ray diffraction was performed on the obtained CoSnC-containing material, a diffraction peak having a wide half-width with a diffraction angle 2θ of 1.0 ° or more was observed between diffraction angles 2θ = 20 ° to 50 °. It was. Further, when XPS was performed on the CoSnC-containing material, the C1s peak in the CoSnC-containing material was obtained in a region lower than 284.5 eV. That is, it was confirmed that carbon in the CoSnC-containing material was bonded to other elements.

  Next, 60 parts by mass of this CoSnC-containing material, 28 parts by mass of artificial graphite as a conductive agent and a negative electrode active material and 2 parts by mass of carbon black, and 10 parts by mass of polyvinylidene fluoride as a binder are mixed. The agent was adjusted. Subsequently, the negative electrode mixture is dispersed in N-methyl-2-pyrrolidone as a solvent to form a negative electrode mixture slurry, which is applied to both surfaces of a negative electrode current collector 22A made of a copper foil having a thickness of 15 μm, and dried. The negative electrode active material layer 22B was formed by compression molding with a press. Thereafter, a negative electrode lead 25 made of nickel was attached to one end of the negative electrode current collector 22A.

  Subsequently, a separator 23 made of a microporous polypropylene film having a thickness of 25 μm was prepared, and a positive electrode 21, a separator 23, a negative electrode 22, and a separator 23 were laminated in this order to form a laminated body. The battery element 20 was produced by winding.

  On the other hand, a first conductive member 31 made of aluminum (Al) and a second conductive member 32 made of copper (Cu) were prepared, and a protrusion 34 was formed on one surface of the first conductive member 31. At that time, in Example 1, three rows of conical protrusions 34 were provided (see FIG. 6). In Example 2, three rows of triangular pyramidal protrusions 34 were provided (see FIG. 8). In Example 3, three rows of quadrangular pyramidal projections 34 were provided (see FIG. 9). In Example 4, one row of conical protrusions 34 was provided (see FIG. 7).

  Next, the surface of the first conductive member 31 on which the protrusions 34 were formed was opposed to the second conductive member 32, and the intermediate member 33 made of polyethylene was laminated therebetween to form the short-circuit member 30. Subsequently, the short-circuit member 30 is disposed in the battery can 11 having an inner dimension in the thickness direction of 6.5 mm, the end of the positive electrode current collector 21A is joined to the first conductive member 31 by welding, and the second conductive member 32 was joined to the battery can 11 by welding.

After that, the battery element 20 is accommodated in the battery can 11, the insulating plate 12 is disposed on the battery element 20, the negative electrode lead 25 is welded to the battery can 11, and the positive electrode lead 24 is connected to the lower end of the positive electrode pin 15. The battery lid 13 was fixed to the open end of the battery can 11 by laser welding. After that, an electrolytic solution was injected into the battery can 11 from the electrolytic solution injection hole 19. As the electrolytic solution, a solution obtained by dissolving LiPF ₆ as an electrolyte salt at a content of 1 mol / dm ³ in a solvent obtained by mixing 50% by volume of ethylene carbonate and 50% by volume of diethyl carbonate was used. Finally, the electrolyte injection hole 19 was closed with a sealing member 19A to obtain a rectangular secondary battery having a thickness of 8 mm, a width of 34 mm, and a height of 42 mm.

  As Comparative Example 1, a secondary battery was fabricated in the same manner as in Example 1 except that the short-circuit member was not provided.

  Five secondary batteries (Battery 1 to Battery 5) of Examples 1 to 4 and Comparative Example 1 thus obtained were produced, and a crush test was performed to examine the presence or absence of ignition or rupture. The obtained results are shown in Table 1.

  As can be seen from Table 1, in Comparative Example 1 in which no short-circuit member is provided, rupture occurred in all five secondary batteries, whereas in Examples 1 to 4 in which short-circuit member 30 was provided, the rupture was suppressed. I was able to. That is, it was found that if the short-circuit member 30 having the above-described structure is provided, safety can be improved even when the battery is crushed or broken and a short-circuit occurs.

  Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above embodiments and examples, and various modifications can be made. For example, in the embodiments and examples described above, the case where the first conductive member 31 is electrically connected to the positive electrode 21 and the second conductive member 32 is electrically connected to the negative electrode 22 has been described. The second conductive member 32 may be electrically connected to the positive electrode 31 to the negative electrode 22. In this case, the constituent material of the first conductive member 31 includes copper (Cu), nickel (Ni), or stainless steel, and the constituent material of the second conductive member 32 includes aluminum (Al).

  Further, for example, the present invention can also be applied when the battery can 11 and the battery lid 13 have a function as a positive electrode terminal. In that case, the battery can 11 or the battery lid 13 itself, or a part thereof, may also serve as the first conductive member 31.

  Furthermore, for example, in the embodiment and the example described above, the case where the first conductive member 31 is provided with the protrusion 34 has been described. However, the protrusion 34 may be provided on the second conductive member 32, You may make it provide in both the 1st conductive member 31 and the 2nd conductive member 32. FIG.

  In addition, for example, the short-circuit member 30 is not limited to one place among the four corners of the battery can 11 and may be provided at two places, three places, or four places. For example, the short-circuit member 30 is not limited to the gap between the battery can 11 and the battery element 20, and may be provided inside the battery element 20.

  Furthermore, in the above-described embodiments and examples, a so-called square battery in which the battery can 11 has a rectangular parallelepiped shape has been described as an example, but the present invention can also be applied to a cylindrical or elliptic battery. The present invention can also be applied to a primary battery.

  In addition, for example, in the above-described embodiments and examples, the case where an electrolytic solution that is a liquid electrolyte is used as a solvent has been described. However, another electrolyte may be used instead of the electrolytic solution. Other electrolytes include, for example, a gel electrolyte in which an electrolyte is held in a polymer compound, a solid electrolyte having ionic conductivity, a mixture of a solid electrolyte and an electrolyte, or a solid electrolyte and a gel electrolyte. And a mixture thereof.

  Note that various polymer compounds can be used for the gel electrolyte as long as it absorbs the electrolyte and gels. Examples of such a polymer compound include a fluorine-based polymer compound such as polyvinylidene fluoride or a copolymer of vinylidene fluoride and hexafluoropropylene, an ether-based polymer such as polyethylene oxide or a crosslinked product containing polyethylene oxide. A molecular compound, polyacrylonitrile, etc. are mentioned. In particular, a fluorine-based polymer compound is desirable from the viewpoint of redox stability.

  As the solid electrolyte, for example, an organic solid electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, or an inorganic solid electrolyte made of ion conductive glass or ionic crystals can be used. At this time, as the polymer compound, for example, an ether polymer compound such as polyethylene oxide or a crosslinked product containing polyethylene oxide, an ester polymer compound such as polymethacrylate, an acrylate polymer compound alone or mixed, Alternatively, it can be used by being copolymerized in the molecule. As the inorganic solid electrolyte, lithium nitride, lithium iodide, or the like can be used.

  In addition, in the above embodiments and examples, the case where lithium is used as the electrode reactant has been described. However, other group 1 elements in the long-period periodic table such as sodium (Na) or potassium (K), or The present invention can also be applied to the case of using elements of Group 2 in the long-period periodic table such as magnesium or calcium (Ca), other light metals such as aluminum, lithium, or alloys thereof. An effect can be obtained. At that time, a negative electrode active material, a positive electrode active material, a solvent, or the like that can occlude and release the electrode reactant is selected according to the electrode reactant.

It is sectional drawing showing the structure of the secondary battery which concerns on the 1st Embodiment of this invention. It is sectional drawing along the II-II line of FIG. It is sectional drawing showing the structure before winding of the positive electrode shown in FIG. It is sectional drawing showing the structure before winding of the negative electrode shown in FIG. It is sectional drawing showing an example of a structure of a short circuit member. It is a top view showing the other example of a structure of a short circuit member. It is a top view showing the further another example of a structure of a short circuit member. It is a top view showing the further another example of a structure of a short circuit member. It is a top view showing the further another example of a structure of a short circuit member. It is sectional drawing for demonstrating the effect | action of a short circuit member when the secondary battery shown in FIG. 1 is crushed. It is a perspective view showing an example of the conventional center pin.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Battery can, 12 ... Insulation board, 13 ... Battery cover, 13A ... Through-hole, 14 ... Terminal board, 15 ... Positive electrode pin, 16 ... Insulation case, 17 ... Gasket, 18 ... Cleavage valve, 19 ... Electrolyte injection hole , 19A ... sealing member, 20 ... battery element, 21 ... positive electrode, 21A ... positive electrode current collector, 21B ... positive electrode active material layer, 21C ... positive electrode coating region, 21D ... positive electrode exposed region, 22 ... negative electrode, 22A ... negative electrode collector Electrical body, 22B ... negative electrode active material layer, 22C ... negative electrode coating region, 22D ... negative electrode exposed region, 23 ... separator, 24 ... positive electrode lead, 25 ... negative electrode lead, 30 ... short circuit member, 31 ... first conductive member, 32 ... Second conductive member 33 ... Intermediate member 34 ... Projection

Claims (5)

A battery comprising a battery element having a positive electrode and a negative electrode, and a battery can containing the battery element,
A first conductive member electrically connected to the positive electrode and a second conductive member electrically connected to the negative electrode are provided with a short-circuit member disposed opposite to each other with an insulating intermediate member therebetween,
At least one of the first conductive member and the second conductive member has a protrusion on the surface facing the other,
The intermediate member has a thickness that is reduced in accordance with an external force applied to the battery can, so that a distance between the first conductive member and the second conductive member is equal to or less than a height of the protrusion. Battery to play. The battery according to claim 1, wherein the short-circuit member is provided in a gap between the battery element and the battery can. The battery element includes a separator between the positive electrode having a positive electrode active material layer on a surface of a strip-shaped positive electrode current collector and the negative electrode having a negative electrode active material layer on a surface of a strip-shaped negative electrode current collector. The battery according to claim 1, wherein the battery has a laminated and wound configuration.   The battery according to claim 1, wherein the negative electrode contains a negative electrode active material containing at least one of tin (Sn) and silicon (Si) as a constituent element. A short-circuit member used for a battery including a battery element having a positive electrode and a negative electrode, and a battery can that houses the battery element,
The first conductive member electrically connected to the positive electrode and the second conductive member electrically connected to the negative electrode are arranged to face each other with an insulating intermediate member interposed therebetween,
At least one of the first conductive member and the second conductive member has a protrusion on the surface facing the other,
The intermediate member has a thickness that is reduced in accordance with an external force applied to the battery can, so that a distance between the first conductive member and the second conductive member is equal to or less than a height of the protrusion. Short-circuit member to be used.

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