JP2009129553A - battery - Google Patents

Abstract

Disclosed is a battery having a plurality of electrode leads, which is excellent in battery space efficiency and easy to manufacture.
A battery element including a positive electrode having an active material layer on a conductive substrate and a negative electrode having an active material layer on a conductive substrate, wound through a separator, and having a center hole penetrating both ends. A plurality of positive leads and negative leads led out from both end faces of the battery element, an electrolyte, a battery can containing the battery element and the electrolyte, and an open end of at least one end of the battery can, and an open end of the battery can In a battery comprising a battery lid and a safety valve for closing the battery, and a relay tab for connecting the positive electrode lead and the safety valve, the plurality of positive electrode leads are folded in the direction of the center hole of the battery element and are not blocked. In this way, it is bent in the direction of the safety valve in the vicinity of the center hole and connected to the relay tab.
[Selection] Figure 1

Description

  The present invention relates to a battery, and more particularly to a non-aqueous electrolyte secondary battery having a plurality of electrode leads and capable of taking out a large current.

  In recent years, with the remarkable development of portable electronic technology, electronic devices such as mobile phones, notebook personal computers, and PDAs (Personal Digital Assistants) have been recognized as fundamental technologies that support an advanced information society. It was. Furthermore, research and development related to the enhancement of the functionality of these devices is being pursued energetically, and the power consumption of electronic devices is steadily increasing in proportion thereto. On the other hand, these electronic devices are required to be driven for a long time, and it has been desired to increase the energy density of the secondary battery, which is a driving power source.

  From the standpoint of the occupied volume and mass of the battery built in the electronic device, the higher the energy density of the battery, the better. Currently, lithium ion secondary batteries using lithium ion doping and dedoping have a higher energy density at higher voltages than other battery systems, so they have been built into most devices. . Such a lithium ion secondary battery has a winding structure in which a positive electrode and a negative electrode are stacked via a separator and wound, for example, in a spiral shape, thereby exhibiting high storage characteristics, load characteristics, and the like. .

  FIG. 17 shows an example of a cross-sectional structure of a conventional lithium ion secondary battery having a winding structure. This lithium ion secondary battery has a battery element 106 in which a strip-like positive electrode 101 and a strip-like negative electrode 102 are wound via a separator 105 inside a battery can 110 having one end closed and the other end open. have. A positive electrode lead 103 made of, for example, aluminum (Al) or the like is connected to the positive electrode 101. The positive electrode lead 103 is led out from one end face of the battery element 10 and welded to the safety valve mechanism 114, thereby being electrically connected to the battery lid 111. In addition, a negative electrode lead 104 made of, for example, nickel (Ni) or the like is connected to the negative electrode 102. The negative electrode lead 104 is led out from the other end surface of the battery element 110 and welded to the battery can 110 to be electrically connected thereto. Hereinafter, when a specific lead is not shown among the positive electrode lead 103 and the negative electrode lead 104, it is referred to as an electrode lead.

  Many studies have been conducted for the purpose of further enhancing the performance and expanding the applications of such lithium ion secondary batteries. As one of them, for example, many proposals have been made to attach a plurality of electrode leads to an electrode as a method of reducing internal resistance in a secondary battery having a high output structure capable of taking out a large current.

  However, when a plurality of electrode leads are used, it is difficult to connect the electrode leads to the battery terminals (the battery lid 111, the safety valve mechanism 114, and the bottom of the battery can 110). As a conventional method, for connecting one or two electrode leads, for example, laser welding is used on the battery lid 111 and the safety valve mechanism 114 side, and resistance welding is often used on the bottom side of the battery can 110. In laser welding, the adhesion of the workpiece to be welded during welding is important. However, when multiple electrode leads are used, the adhesion between the electrode leads and between the electrode leads and the safety valve mechanism 114 is difficult to achieve and stable. It is difficult to weld. On the other hand, in resistance welding to the bottom of the battery can 110, welding is performed using the resistance between the workpieces. However, in a plurality of electrode leads, the welded portions overlap in multiple layers, and the resistance between the respective layers is reduced. Because of non-uniformity, stable welding is difficult.

  Therefore, in order to cope with such a problem, Patent Document 1 below discloses a method of bundling a plurality of electrode leads and press-connecting them to a component with an arm to connect to a battery lid.

Japanese Patent No. 3806585

  Patent Document 2 below proposes a method of joining only one main conductive tab to a terminal member by joining another conductive tab to one of the plurality of conductive tabs, which is the main conductive tab. .

Japanese Patent No. 3119259

  However, in the method described in Patent Document 1, since a plurality of electrode leads are bundled and pressed against a component with an arm and connected to the battery lid, the space including the routing of these components and electrode leads is not contained in the battery can. Is required. That is, space efficiency is reduced. Further, the structure of the battery terminal becomes complicated due to an increase in the number of parts.

  Furthermore, in order to press-contact a plurality of electrode leads to a component with an arm, as shown in FIG. 18, it is necessary to lead the plurality of electrode leads 123 in a row on the same radial line on the end face of the battery element 106. Since there are tolerances such as the thickness of the electrode and the attachment position of the electrode lead 123, it is actually difficult to lead the electrode lead 123 in a row at the end face of the battery element 106. When the plurality of electrode leads 123 are not led out in a row on the end face of the battery element 106, it is difficult to bundle the electrode leads 123 together and press the parts, and there is a concern that productivity may be reduced. On the other hand, when the tolerances are reduced and the electrode leads 123 are led out in a row, the manufacturing becomes difficult, and the cost increases and the yield decreases.

  In addition, although the space efficiency is improved by the method described in Patent Document 2, in the battery element in which a plurality of conductive tabs are attached to the electrode at equal intervals, the main conductive tab and the other conductive tabs are formed on the end face of the battery element. Conductive tabs cannot be led out in a row. Patent Document 2 does not describe in detail how to join other conductive tabs to the main conductive tab, but when the main conductive tab and the other conductive tabs are not derived in a row, joining them is This is a very difficult and complex task, which leads to reduced productivity. Even if the main conductive tab and other conductive tabs are designed to be led out in a row, there are actually tolerances in the electrode thickness and the connection position of the main conductive tab and other conductive tabs. These tabs are rarely drawn in a row at the end face. Therefore, when there is a deviation in the positions where the main conductive tab and other conductive tabs are led out, it is difficult to manufacture a battery by this method, and productivity is lowered.

  Accordingly, it is an object of the present invention to provide a battery having a plurality of electrode leads, which has high space efficiency and can be easily manufactured.

In order to solve the above-described problems, the present invention provides:
A battery element having a center hole penetrating both end faces, a positive electrode having an active material layer on a conductive substrate and a negative electrode having an active material layer on a conductive substrate wound through a separator;
A plurality of positive leads and negative leads respectively derived from both end faces of the battery element;
Electrolyte,
A battery can containing a battery element and an electrolyte, at least one end of which is opened; and
A battery lid and a safety valve for closing the open end of the battery can, and a relay tab for connecting the positive electrode lead and the safety valve;
The plurality of positive leads are bent and overlapped in the direction of the center hole of the battery element, and are bent in the direction of the safety valve in the vicinity of the center hole and connected to the relay tab so as not to block the center hole. Battery.

  In the present invention, when a circle centered on the center hole is drawn, the positions where the plurality of positive electrode leads are led out are preferably arranged within a circle center angle of 135 °. This is because it is easy to bundle the positive leads when the plurality of positive leads are bent in the vicinity of the center hole.

  In the present invention, the cross-sectional area of the relay tab is preferably larger than the sum of the cross-sectional areas of the plurality of positive electrode leads. This is because the battery resistance is lowered and the cycle characteristics can be improved.

  According to the present invention, in the plurality of positive leads, the length of the positive lead derived from the inner periphery of the battery element is shorter than the length of the positive lead derived from the outer periphery of the battery element. preferable. This is because the length of each positive electrode lead can be made uniform when bent in the direction of the center hole of the battery element.

  Moreover, in this invention, it is preferable that a some positive electrode lead and relay tabs are connected by ultrasonic welding.

  In the present invention, the plurality of negative electrode leads are folded in the direction of the center hole of the battery element and overlapped, and are folded in the direction of the battery can in the vicinity of the center hole so as not to block the center hole. It is preferable to be connected. Since the center hole of the battery element is not blocked, a welding rod can be inserted from the center hole, and resistance welding between the bottom of the battery can and the negative electrode lead can be performed. This is because it can be easily performed.

  In the present invention, it is preferable that the plurality of negative electrode leads be bent in the direction of the battery can bottom in the vicinity of the center hole and connected by ultrasonic welding. This is because since the plurality of negative electrode leads are connected by welding, the bottom of the battery can and the negative electrode lead can be easily welded.

  Further, in the present invention, when a circle centered on the center hole is drawn, the positions where the plurality of negative electrode leads are led out are preferably arranged within a circle center angle of 135 °. This is because it is easy to bundle the negative electrode leads when the plurality of negative electrode leads are bent in the vicinity of the center hole.

  In the present invention, in the plurality of negative electrode leads, the length of the negative electrode lead derived from the inner peripheral portion of the battery element is shorter than the length of the negative electrode lead derived from the outer peripheral portion of the battery element. preferable. This is because the length of each negative electrode lead can be made uniform when bent in the direction of the center hole of the battery element.

  Moreover, in this invention, it is preferable that a some negative electrode lead and the said battery can are connected by resistance welding.

  According to this invention, in a battery including a plurality of electrode leads, the positive electrode lead and the safety valve can be connected via the relay tab by bending the positive electrode lead in the vicinity of the center hole and connecting it to the relay tab. Therefore, electrical connection between the plurality of positive electrode leads and the safety valve can be easily performed.

  Further, since it is not necessary to provide special parts for connecting the positive lead, it is not necessary to secure a space for providing these parts.

  According to this invention, in a battery including a plurality of electrode leads, the battery can be easily manufactured, and the productivity of the battery can be improved. In addition, a battery with high space efficiency can be obtained.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

(1) Configuration of Battery FIG. 1 shows a cross-sectional structure of a battery according to an embodiment of the present invention. This battery is a so-called cylindrical type, in which a strip-shaped positive electrode 11 and a strip-shaped negative electrode 12 are wound through a separator 13 inside a substantially hollow cylindrical battery can 20 as an exterior material. It has the element 10 and is sealed with a battery lid 30.

  The battery can 20 is made of, for example, iron (Fe) plated with nickel (Ni), and has one end closed and the other end open. At the open end of the battery can 20, there are a battery lid 30, a safety valve mechanism 40 provided inside the battery lid 30, and, if necessary, a thermal resistance element (Positive Temperature Coefficient; PTC element) 44, It is attached by caulking through a gasket 50. Although not shown, a pair of insulating plates may be arranged on the winding end surface of the battery element 10 so as to sandwich the battery element 10.

  FIG. 2 is an example of a perspective view of a half part of the PTC element 44 and the safety valve mechanism 40. The safety valve mechanism 40 includes a safety valve 41 made of a metal material made of aluminum or the like, a support holder 42 made of a metal material such as aluminum, an insulating holder 43, and a connection portion 45 to which the positive electrode lead 15 is connected.

  The safety valve 41 and the support holder 42 are fitted via the insulating holder 43. The safety valve 41 has a protrusion 41 a that protrudes toward the battery element 10 at the center of the bottom, and the protrusion 41 a is inserted into a hole 42 a formed at the center of the bottom of the support holder 42. On the outer periphery of the safety valve 41, a flange portion 41b is provided for ensuring electrical connection with the battery lid 30 with the PTC element 44 interposed therebetween. The support holder 42 has a hole portion 42a for connecting the safety valve 41 and the connection portion 45 at a substantially central portion, and openings 42b as a plurality of ventilation holes are provided around 42a.

  Similarly to the safety valve 41, the connection portion 45 is made of a conductive metal material such as aluminum, and is electrically connected to the protruding portion 41 a of the safety valve 41 via the support holder 42. The connection part 45 and the safety valve 41 are connected by welding, for example. In addition, since the connection part of the connection part 45 and the safety valve 41 becomes an electrical interruption | blocking part, these connections ensure the connection intensity | strength of the level which does not produce a connection defect, but when an internal pressure rises by overcharge etc., it is quick. The connection strength should be such that the connection is released. Further, the relay tab 16 connected to the positive electrode lead 15 is connected to the surface of the connection portion 45 opposite to the contact surface with the safety valve 41 by welding or the like.

  In the safety valve mechanism 40, when the internal pressure of the battery rises and reaches a predetermined value due to internal short circuit or external heating, the increased internal pressure is transmitted to the safety valve 41 through the opening 42b of the support holder 42. The safety valve 41 is deformed toward the battery lid 30 by its internal pressure. As a result, the internal pressure of the battery is relaxed, the electrical connection between the safety valve 41 and the relay tab 16 is interrupted, and the electrical connection between the battery lid 30 and the battery element 10 is disconnected. When the temperature rises, the PTC element 44 limits the current by increasing the resistance value and prevents abnormal heat generation due to a large current.

  Returning to FIG. 1, the battery lid 30 functions as a positive electrode terminal of the battery and is made of, for example, stainless steel plated with nickel (Ni). The gasket 50 is made of, for example, an insulating material, and asphalt is applied to the surface.

  In the battery element 10, a strip-like positive electrode 11 and a negative electrode 12 are wound through a separator 13, and the separator 13 is impregnated with an electrolytic solution that is a liquid electrolyte. A center pin 14 is inserted into a center hole 18 formed at a substantially central portion of the end face of the battery element 10. Hereinafter, the configuration of the positive electrode 11 and the negative electrode 12 will be described.

[Positive electrode]
The positive electrode 11 includes a positive electrode current collector 11a having a band shape and a positive electrode active material layer 11b formed on both surfaces of the positive electrode current collector 11a. The positive electrode current collector 11a includes a plurality of positive electrode leads 15a. The positive lead 15b, the positive lead 15c, and the positive lead 15d (hereinafter referred to as the positive lead 15 when a specific positive lead is not shown) are connected. Note that the number of the positive leads 15 is not particularly limited. The positive electrode current collector 11a is made of a metal foil such as an aluminum (Al) foil, a nickel (Ni) foil, or a stainless (SUS) foil. The positive electrode lead 15 is preferably a metal foil such as aluminum (Al), and the positive electrode lead 15 is preferably connected to a portion of the positive electrode current collector 11a where the positive electrode active material layer 11b is not provided.

  The positive electrode lead 15 is electrically connected to the battery lid 30 by being connected to the connection portion 45 of the safety valve mechanism 40 via the relay tab 16 that is a metal foil such as aluminum (Al).

  The connection between the positive electrode lead 15 and the relay tab 16 will be described with reference to FIGS. 3 and 4. FIG. 3 is an enlarged cross-sectional view showing an example of the configuration of the open end portion of the battery can 20, and FIG. 4 is a schematic view of the battery element 10 as viewed from the end face side from which the positive electrode lead 15 is led out.

  As shown in FIG. 3, the plurality of positive electrode leads 15 are led out from the end face of the battery element 10. The positive electrode lead 15 is bent and overlapped toward the center hole 18 in which the center pin 14 is inserted, and is bent in the direction of the safety valve mechanism 40 in the vicinity of the center hole 18 so as not to block the center hole 18. They are bundled and connected to the relay tab 16.

  Here, it is preferable that the plurality of positive electrode leads 15 are led out from the direction of approximately the same angle around the center hole 18 on the end face of the battery element 10. Specifically, as shown in FIG. 4, when a circle centered on the center hole 18 is drawn on the end face of the battery element 10, the position where the plurality of positive electrode leads 15 are led is such that the center angle α of the circle is It is preferable to arrange in a region within 135 °. A plurality of positive leads 15 are slightly deviated in the positions where they are derived depending on tolerances such as the thickness of the positive electrode 11 and the negative electrode 12 and the attachment positions of the positive electrodes 15. This is because, if the region is within the central angle of 135 °, it is easy to bundle when bent in the vicinity of the central hole 18, and the connection with the relay tab 16 becomes easy.

  The length of the positive lead 15 may be any length as long as it can be bent from the position where each positive lead 15 is led out toward the center hole 18 and connected to the relay tab 16. Since the distance from the position to the center hole 18 is different, it is preferable that the distance is appropriately adjusted according to the position where each positive electrode lead 15 is led out. That is, the length of the positive electrode lead 15 derived from the inner peripheral portion of the battery element 10 is preferably shorter than the length of the positive electrode lead 15 derived from the outer peripheral portion of the battery element 10. This is because the length of each positive electrode lead 15 can be made uniform when the positive electrode lead 15 is bent in the direction of the center hole 18.

  The width of the positive electrode lead 15 is appropriately selected according to the size of the battery and the like, and can be, for example, about 2 mm to 10 mm. Further, the thickness of the positive electrode lead 15 can be set to, for example, about 50 μm to 300 μm.

  The length of the relay tab 16 may be a minimum length that can be connected to each of the positive electrode lead 15 and the safety valve mechanism 40 and relayed between them. The width of the relay tab 16 can be, for example, about 2 mm to 10 mm. The thickness of the relay tab 16 can be, for example, about 100 μm to 500 μm.

  In addition, the cross-sectional area of the relay tab 16 is preferably larger than the sum of the cross-sectional areas of the plurality of positive electrode leads 15. This is because the resistance of the battery can be reduced, temperature rise can be suppressed, and cycle characteristics can be improved. The cross-sectional areas of the relay tab 16 and the positive electrode lead 15 are obtained by multiplying the width and thickness of each.

  The positive electrode active material layer 11b includes, for example, a positive electrode active material, and may include a conductive agent such as graphite and a binder such as polyvinylidene fluoride as necessary. In addition, what combined the positive electrode active material and the electrically conductive agent and the fixing agent as needed is hereafter called a positive electrode mixture suitably.

The positive electrode active material is mainly Li _x MO ₂ (wherein M represents one or more transition metals, x is different depending on the charge / discharge state of the battery and is usually 0.05 or more and 1.10 or less). A composite oxide of lithium and a transition metal is used. As a transition metal constituting the lithium composite oxide, cobalt (Co), nickel (Ni), manganese (Mn), or the like is used.

Specific examples of such a lithium composite oxide include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _y Co _1-y O ₂ (0 <y <1). A solid solution in which a part of the transition metal element is substituted with another element can also be used. Examples thereof include LiNi _0.5 Co _0.5 O ₂ and LiNi _0.8 Co _0.2 O ₂ . These lithium composite oxides can generate a high voltage and have an excellent energy density. _{Furthermore, TiS 2, MoS 2, V} 2 O no lithium metal sulfides such as ₅ or may be used an oxide as the positive electrode active material.

  As the conductive agent, for example, a carbon material such as carbon black or graphite is used. As the binder, for example, polyvinylidene fluoride (PVdF), polytetrafluoroethylene, polyvinylidene fluoride, or the like is used.

[Negative electrode]
The negative electrode 12 includes a negative electrode current collector 12a having a strip shape and negative electrode active material layers 12b formed on both surfaces of the negative electrode current collector 12a. The negative electrode current collector 12a includes a plurality of negative electrode leads 17a, A negative electrode lead 17b and a negative electrode lead 17c (hereinafter referred to as a negative electrode lead 17 when a specific negative electrode lead is not shown) are connected. The number of negative electrode leads 17 is not particularly limited. The negative electrode current collector 12a is made of a metal foil such as a copper (Cu) foil, a nickel (Ni) foil, or a stainless steel (SUS) foil. The negative electrode lead 17 is a metal foil such as copper (Cu) or nickel (Ni), and the negative electrode lead 17 may be connected to a portion of the negative electrode current collector 12a where the negative electrode active material layer 12b is not provided. preferable.

  The negative electrode lead 17 is welded and electrically connected to the battery can 20. In FIG. 5, the expanded sectional view which shows the structure of the bottom part of the battery can 20 is shown. As shown in FIG. 5, the plurality of negative electrode leads 17 are led out from the end face of the battery element 10. The negative electrode lead 17 is folded and overlapped toward the center hole 18 in which the center pin 14 is inserted, and is bent in the direction of the battery can 20 near the center hole 18 so as not to block the center hole 18. The battery can 20 is bent along the bottom of the battery can 20 and connected to the battery can 20.

  Similarly to the positive electrode lead 15, the positions where the plurality of negative electrode leads 17 are led out on the end face of the battery element 10 are arranged in a region within a circle center angle of 135 ° when a circle centered on the center hole 18 is drawn. It is preferable that This is because it is easy to bundle when bent in the vicinity of the center hole 18, it is easy to weld a plurality of leads together, and connection to the bottom of the battery can 20 is facilitated.

  The length of the negative electrode lead 17 may be any length as long as it can be bent from the position where each negative electrode lead 17 is led out toward the center hole 18 and connected to the bottom of the battery can 20. It is preferable to adjust appropriately according to the position where it is made. That is, the length of the negative electrode lead 17 led out from the inner peripheral part of the battery element 10 is preferably shorter than the length of the negative electrode lead 17 led out from the outer peripheral part of the battery element 10. This is because when the negative electrode lead 17 is bent in the direction of the center hole 18, the lengths of the respective negative electrode leads 17 can be made uniform.

  The width of the negative electrode lead 17 is appropriately selected according to the size of the battery and the like, and can be, for example, about 2 mm to 10 mm. Moreover, the thickness of the negative electrode lead 17 can be set to, for example, about 50 μm to 300 μm.

  The negative electrode active material layer 12b includes, for example, a negative electrode active material, a conductive agent if necessary, and a binder. In addition, what combined the negative electrode active material, the electrically conductive agent if necessary, and the binder is suitably called a negative electrode mixture below.

As the negative electrode active material, lithium metal, a lithium alloy, a carbon material that can be doped / undoped with lithium, or a composite material of a metal material and a carbon material is used. Specific examples of carbon materials that can be doped / undoped with lithium include graphite, non-graphitizable carbon, graphitizable carbon, and the like. More specifically, pyrolytic carbons and cokes (pitch coke, needle coke). , Petroleum coke), graphites, glassy carbons, organic polymer compound fired bodies (phenol resins, furan resins, etc., calcined at an appropriate temperature), carbon fibers, activated carbon and other carbon materials are used. be able to. Further, lithium doped as the dedoping can material, may be used polyacetylene, an oxide of _2, such as polymers and SnO polypyrrole.

  In addition, various types of metal elements and metalloid elements can be used as materials capable of alloying lithium, but these may be simple substances, alloys or compounds, and one or more of these phases may be used. It may be at least partly. In the present invention, the alloy includes an alloy containing one or more metal elements and one or more metalloid elements in addition to an alloy composed of two or more metal elements. Moreover, the nonmetallic element may be included. Some of the structures include a solid solution, a eutectic (eutectic mixture), an intermetallic compound, or two or more of them.

  Specific examples of such a metal element or metalloid element include magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon, germanium (Ge), and tin. (Sn), lead (Pb), bismuth (Bi), cadmium (Cd), silver (Ag), zinc (Zn), hafnium (Hf), zirconium (Zr), yttrium (Y), palladium (Pd) or platinum (Pt) etc. are mentioned.

  Among these elements, those containing a group 14 metal element or metalloid element in the long-period periodic table as a constituent element are preferred, and those containing at least one of silicon and tin as a constituent element are particularly preferred. 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.

  An alloy containing tin (Sn), cobalt (Co), and carbon (C) can also be used.

  As the binder, for example, polyvinylidene fluoride (PVdF), styrene butadiene rubber or the like is used.

[Separator]
The separator 13 is composed of, for example, a porous film made of a polyolefin-based material such as polypropylene (PP) or polyethylene (PE), or a porous film made of an inorganic material such as a ceramic nonwoven fabric. The porous film may be laminated. Among these, polyethylene and polypropylene porous films are the most effective.

  The thickness of the separator 13 is preferably 5 μm to 50 μm, more preferably 7 μm to 30 μm. If the separator 13 is too thick, the filling amount of the active material is reduced to reduce the battery capacity, and the ionic conductivity is reduced to deteriorate the current characteristics. On the other hand, if the film is too thin, the mechanical strength of the film decreases.

[Electrolytes]
The separator 13 described above is impregnated with a non-aqueous electrolyte that is a liquid non-aqueous electrolyte. As the non-aqueous electrolyte, an electrolyte salt and an organic solvent that are generally used in non-aqueous electrolyte batteries can be used.

  Specific examples of the non-aqueous solvent include ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), dipropyl carbonate ( DPC), ethylpropyl carbonate (EPC), or a solvent in which hydrogen of these carbonates is substituted with halogen. One of these solvents may be used alone, or a plurality of these solvents may be mixed with a predetermined composition.

Moreover, as an electrolyte salt, it is possible to use the material used for a normal non-aqueous electrolyte. Specifically, LiCl, LiBr, LiI, LiClO ₃ , LiClO ₄ , LiBF ₄ , LiPF ₆ , LiNO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAsF ₆ , LiCF ₃ SO ₃ , LiC (SO ₂ CF ₃ ) ₃ , LiAlCl ₄ , LiSiF _{6 and the} like can be mentioned, but LiPF ₆ and LiBF ₄ are preferable from the viewpoint of oxidation stability. These lithium salts may be used alone or in combination of two or more. There is no problem as long as the lithium salt can be dissolved in the above solvent, but the lithium ion concentration is 0.4 mol / kg or more and 2.0 mol / kg or less with respect to the non-aqueous solvent. Preferably there is.

  In the case of using a gel-like gel electrolyte, the above-mentioned electrolytic solution is gelled with a matrix polymer. The matrix polymer only needs to be compatible with a non-aqueous electrolyte solution obtained by dissolving the electrolyte salt in the non-aqueous solvent and can be gelled. Examples of such a matrix polymer include fluorine polymer compounds such as copolymers with polyvinylidene fluoride, ether polymer compounds such as polyethylene oxide or a crosslinked product containing polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethacrylate. Examples thereof include polymers containing ronitrile in the repeating unit. Such a polymer may be used individually by 1 type, and may mix and use 2 or more types.

Among them, a fluorine polymer compound is particularly preferable from the viewpoint of redox stability. For example, a copolymer in which hexafluoropropylene is introduced into polyvinylidene fluoride at a ratio of 75.0% by weight or less can be used. Such polymers have a number average molecular weight in the range of 5.0 × 10 ⁵ to 7.0 × 10 ⁵ (500,000 to 700,000) or a weight average molecular weight of 2.1 × 10 ⁵ to 3. The range is 1 × 10 ⁵ (210,000-310,000), and the intrinsic viscosity is in the range of 1.7 (dl / g) to 2.1 (dl / g).

(2) Production of Battery Next, a method for producing a cylindrical battery applicable to the first embodiment of the present invention will be described.

[Production of positive electrode]
The above-described positive electrode active material, binder, and conductive agent are uniformly mixed to form a positive electrode mixture, and this positive electrode mixture is dispersed in a solvent to form a slurry. Next, this slurry is uniformly applied on the belt-like positive electrode current collector 11a by a doctor blade method or the like, then dried at a high temperature to drive off the solvent, and further subjected to compression molding with a roller press or the like, thereby forming a positive electrode active material layer 11b is formed. In addition, as a solvent, N-methyl-2-pyrrolidone (NMP) etc. are used, for example. The positive electrode active material, the conductive agent, the binder, and the solvent only need to be uniformly dispersed, and the mixing ratio is not limited.

  Next, the positive electrode active material layer 11b to which the positive electrode lead 15 is attached is peeled off from the positive electrode current collector 11a, and a plurality of positive electrode leads 15 are connected by, for example, ultrasonic welding as shown in FIG. 6A. When the positive electrode lead 15 is made of, for example, an aluminum foil, aluminum has a low specific heat and a low resistance, so that resistance welding makes it easy to make a hole in the weld, but such a problem can be solved by ultrasonic welding.

  As shown in FIG. 6B, each positive electrode lead 15 is positioned at a position where it is led out from the direction of approximately the same angle around the center hole 18 on the end face of the battery element 10 after winding, and is equally spaced as much as possible. It is preferable to be connected to such a position. It can be easily bundled when bent in the vicinity of the center hole 18, can be easily connected to the relay tab 16, can have a uniform current distribution, and can reduce the internal resistance of the battery and improve the current collecting performance. Because.

  Further, it is preferable to adjust the length of each positive electrode lead 15 so that the tip of the positive electrode lead 15 comes beyond the central hole 18 when the positive electrode lead 15 is bent in the direction of the central hole 18 after winding. That is, it is preferable that the length of the positive electrode lead 15 derived from the inner peripheral portion of the battery element 10 is shorter than the length of the positive electrode lead 15 derived from the outer peripheral portion of the battery element 10. This is because, when the positive electrode lead 15 is bent in the direction of the center hole 18, it is possible to omit the step of cutting in order to align the length of each positive electrode lead 15. 6 to 12 below show an example in which four positive leads 15 and four negative leads 17 are connected, but the number of positive leads 15 and negative leads 17 is not limited.

[Preparation of negative electrode]
The negative electrode active material described above, and if necessary, a binder and a conductive agent are uniformly mixed to form a negative electrode mixture, and the negative electrode mixture is dispersed in a solvent to form a slurry. Next, this slurry is uniformly coated on the strip-shaped negative electrode current collector 12a by a doctor blade method or the like, dried at a high temperature to drive off the solvent, and further subjected to compression molding with a roller press or the like to form the negative electrode active material layer 12b. It is formed. Here, the mixing ratio of the negative electrode active material, the conductive agent, the binder, and the solvent is not limited as in the positive electrode active material.

  Next, the negative electrode active material layer 12b where the negative electrode lead 17 is attached to the negative electrode current collector 12a is peeled off, and a plurality of negative electrode leads 17 are connected by, for example, ultrasonic welding as shown in FIG. 6A. Similarly to the positive electrode lead 15, the position where the negative electrode lead 17 is connected is such that the end surface of the wound battery element 10 is led out from the direction of approximately the same angle with the central hole 18 as the center, and as much as possible. It is preferable to connect to positions that are equally spaced. In addition, the length of the negative electrode lead 17 led out from the inner peripheral portion of the battery element 10 is preferably shorter than the length of the negative electrode lead 17 led out from the outer peripheral portion of the battery element 10.

[Production of battery element and battery]
After the positive electrode 11 having the strip shape obtained as described above and the negative electrode 12 are laminated in the order of the positive electrode 11, the separator 13, the negative electrode 12, and the separator 13, for example, the direction (longitudinal direction) shown by the arrow in FIG. The battery element 10 as shown in FIG. 6B is produced by winding a large number of turns in the direction).

  FIG. 7A is a schematic view of the battery element 10 shown in FIG. 6B when viewed from the end face side from which the positive electrode lead 15 is led out. Each positive lead 15 has a slight deviation in the position derived by tolerances such as the thickness of the positive electrode 11 and the negative electrode 12 and the mounting position of each positive electrode lead 15, but the positions where the plurality of positive leads 15 are derived are as follows. When a circle centered on the center hole 18 is drawn on the end face of the battery element 10, it is preferably arranged within a circle center angle of 135 °.

  Next, the positive electrode lead 15 is bent in the direction of the center hole 18 along the end surface of the battery element 10 as shown in FIG. 7B. Thereby, even when there is a deviation in the angle at which each positive electrode lead 15 is led out, each positive electrode lead 15 can be overlapped. Subsequently, the superimposed positive electrode lead 15 is bent in a direction opposite to the end face of the battery element 10 at a position indicated by a dotted line of arrow A in FIG. 7B and in the vicinity of the central hole 18 so as not to block the central hole 18. The battery element 10 is bent in the direction opposite to the end face.

  Similarly to the positive electrode lead 15 described with reference to FIGS. 7A and 7B, the negative electrode lead 17 is also folded along the end surface of the battery element 10 in the direction of the center hole 18 and overlapped. 17 is bent in the direction opposite to the end face of the battery element 10 in the vicinity of the center hole 18 so as not to block the center hole 18.

  The battery element 10 as shown in FIG. 7C is obtained by bending the positive electrode lead 15 and the negative electrode lead 17 as described above.

  Next, as shown in FIG. 8A, the positive electrode lead 15 and the relay tab 16 are connected by ultrasonic welding. In ultrasonic welding, the positive electrode lead 15 and the relay tab 16 are pressed from the directions of arrows B and C in FIG. 8A in a state where the relay tab 16 is held so as to be substantially perpendicular to the end face of the battery element 10. Is done.

  8B is a schematic view when the battery element 10 shown in FIG. 8A is viewed from the direction indicated by the arrow B. FIG. As shown in FIG. 8B, the main surface of the positive electrode lead 15 and the main surface of the relay tab 16 are connected to face each other.

  Further, as shown in FIG. 9A, the negative electrode lead 17 is connected by ultrasonic welding. Ultrasonic welding is performed by press-contacting a plurality of negative electrode leads 17 from the directions of arrows B and C in FIG. 9A with the negative electrode leads 17 held substantially perpendicular to the end face of the battery element 10. Done.

  FIG. 9B is a schematic view of the battery element 10 shown in FIG. 9A when viewed from the direction of arrow C. As shown in FIG. 9B, the main surfaces of the plurality of negative electrode leads 17 are connected to face each other.

  Subsequently, as shown in FIG. 10A, the negative electrode lead 17 that is bent and welded in the vicinity of the center hole 18 is bent in the direction of the center hole 18 so as to be substantially parallel to the end face of the battery element 10.

  The battery element 10 obtained as described above is inserted into a battery can 20 having one end closed and the other end open as shown in FIG. 10B, and the negative electrode 17 and the bottom of the battery can 20 are connected. Connect by resistance welding. When resistance welding is performed, it is necessary to insert the welding electrode rod from the open end of the battery can 20 through the center hole 18 as shown by an arrow D in FIG. 10B. Is bent in the vicinity of the center hole 18 and does not hinder resistance welding. In addition, if resistance welding of a plurality of negative electrode leads 17 is attempted at a time, stable welding cannot be performed due to variation in resistance of each negative electrode lead 17, but as described above, the plurality of negative electrode leads 17 are subjected to ultrasonic welding. By welding once, it is only necessary to weld the surface of the negative electrode lead 17 facing the battery can 20 and the bottom of the battery can 20, so that resistance welding can be easily performed.

  Next, beading is performed on the open end of the battery can 20 to form a constriction for crimping the safety valve mechanism 40 and the battery lid 30, and the electrolyte is injected.

  Subsequently, as shown by an arrow E in FIG. 11A, the safety valve mechanism 40 is connected to the relay tab 16 protruding from the battery can 20 by laser welding. At this time, since the relay tab 16 projects substantially perpendicularly from the vicinity of the center hole 16 toward the opening of the battery can 20 in the battery element 10, the safety valve mechanism 40 can be easily operated without correcting the position of the relay tab 16. Can be welded. That is, it can manufacture without increasing a process.

  11B is a schematic diagram when the battery shown in FIG. 11A is viewed from the direction of arrow E. FIG. Here, an example in which welding is performed with the relay tab 16 in a state where the safety valve mechanism 40 and the battery lid 30 are assembled is illustrated. However, for example, after the relay tab 16 and the connection portion 45 of the safety valve mechanism 40 are welded, The mechanism 40 and the battery lid 30 may be assembled.

  Subsequently, as shown in FIG. 12, the positive electrode lead 15 is bent in the direction of the center hole 18 so that the relay tab 16 and the end face of the battery element 10 are parallel to each other and welded to the safety valve mechanism 40 of the relay tab 16. Bend the side that is about 180 degrees. Thereafter, the safety valve mechanism 40 and the battery lid 30 are fixed to the open end of the battery can 20 by crimping via the gasket 50, and the battery according to the embodiment of the present invention is manufactured. In FIG. 12, the illustration of the gasket 50 is omitted for simplicity.

  The battery according to the embodiment of the present invention can obtain the following effects. Since the plurality of positive electrode leads 15 are folded in the direction of the central hole 18 of the battery element 10 and overlapped, and are folded in the vicinity of the central hole 18 so as not to block the central hole 18, they are connected to the relay tab 16. Even when there is a slight deviation in the position where the positive electrode lead 15 is led out on the end face of the battery element 10, the connection to the safety valve mechanism 40 can be easily performed via the relay tab 16.

  Similarly, the plurality of negative electrode leads 17 are folded and overlapped in the direction of the center hole 18 of the battery element 10, and are bent in the direction of the battery can 20 near the center hole 18 so as not to block the center hole 18. Since they are bundled, connection to the battery can 20 can be easily performed. Further, resistance welding can be performed using the center hole 18. Therefore, the battery can be easily manufactured, and the productivity of the battery can be improved.

  In addition, since it is not necessary to provide special parts for connecting the positive electrode lead 15 and the negative electrode lead 17, it is possible to suppress an increase in cost due to an increase in the parts, and it is not necessary to secure a space for providing the parts. A battery with high space efficiency can be obtained.

  Specific embodiments of the present invention will be described below with reference to examples, but the present invention is not limited thereto.

<Sample 1>
[Preparation of positive electrode]
42 parts by weight of lithium cobaltate (LiCoO ₂ ) powder as an active material, 42 parts by weight of lithium manganate (LiMn ₂ O ₄ ), 4 parts by weight of polyvinylidene fluoride as a binder, and 2 parts of artificial graphite as a conductive agent Part and N-methylpyrrolidone outside the amount were kneaded to obtain a positive electrode mixture paint. This positive electrode mixture paint is applied to both surfaces of a positive electrode current collector 11a made of a strip-shaped aluminum foil having a thickness of 20 μm, dried, and then pressed to form a positive electrode active material layer 11b. The positive electrode active material layer 11b was peeled off, and an aluminum positive electrode lead 15 having a thickness of 100 μm and a width of 5 mm was connected by ultrasonic welding to obtain the positive electrode 11. Note that the number of the positive leads 15 is four, and these are positions where the positive leads 15 are led out from the end face of the battery element 10 after being wound from approximately the same angle and are equally spaced as much as possible. Connected to. Further, the length of each positive electrode lead 15 was adjusted in advance to such a length that the tip of the positive electrode lead 15 would come beyond the center hole 18 when bent in the direction of the center hole 18 after winding. The total cross-sectional area of the positive electrode lead 15 is 2 mm ² .

[Preparation of negative electrode]
90 parts by weight of artificial graphite as a negative electrode active material, 10 parts by weight of polyvinylidene fluoride (PVdF) as a binder, and N-methylpyrrolidone outside the amount were kneaded to obtain a negative electrode mixture paint. This negative electrode mixture paint is applied to both surfaces of a negative electrode current collector 12a made of a strip-shaped copper foil having a thickness of 15 μm, dried, and pressed to form a negative electrode active material layer 12b. The negative electrode active material layer 11b was peeled off, and a nickel negative electrode lead 15 having a thickness of 100 μm and a width of 5 mm was connected by ultrasonic welding to obtain a negative electrode 12. The number of negative electrode leads 17 was four, and the connection position and length of each negative electrode lead 17 were the same as those of the positive electrode lead 15.

  The negative electrode 12 was made wider and longer than the positive electrode 11 so that the positive electrode active material layer 11 b did not protrude from the negative electrode active material layer 12 b except for the connection portion of the negative electrode lead 17.

  In addition, in the process of coating and forming the positive electrode active material layer 11b and the negative electrode active material layer 12b, respectively, the lithium storage capacity per weight of the negative electrode mixture and the lithium release capacity per weight of the positive electrode mixture are previously set. The lithium storage capacity per unit area of the negative electrode active material layer 12b was not exceeded the lithium release capacity per unit area of the positive electrode active material layer 11b.

[Production of battery element and battery]
Using the positive electrode and the negative electrode prepared as described above as separators, the battery element 10 was manufactured by winding a number of times through a 25 μm-thick polyethylene microporous film. Thereafter, the positive electrode lead 15 and the negative electrode lead 17 led out from both end faces of the battery element 10 are folded in the direction of the central hole 18 and overlapped, and then the vicinity of the central hole 18 is not closed so as not to block the central hole 18. And bent in a direction perpendicular to the end face of the battery element 10.

Next, the relay tab 16 having a thickness of 200 μm and a width of 10 mm and the positive electrode lead 15 were connected by ultrasonic welding. At this time, the relay tab 16 was connected so as to be substantially perpendicular to the end face of the battery element 10. The cross-sectional area of the relay tab 16 is 2 mm ² .

  Further, the negative electrode lead 17 was welded by ultrasonic welding in a state in which the negative electrode lead 17 was bent in a direction perpendicular to the end face of the battery element 10, and then bent so as to be parallel to the end face of the battery element 10.

  Subsequently, the battery element 10 is inserted into the battery can 20 whose one end is open, and a welding electrode rod is inserted from the center hole 18 of the battery element 10, whereby the negative electrode lead 17 is resistance-welded to the bottom of the battery can 20. Connected.

Moreover, after the constriction for crimping the safety valve mechanism 40 and the battery cover 30 was formed in the open end part of the battery can 20 by beading, the electrolyte solution was injected. As the electrolytic solution, a solution obtained by dissolving LiPF ₆ as an electrolyte salt to 1.0 mol / kg in a solvent in which ethylene carbonate and dimethyl carbonate were mixed at a weight ratio of 3: 7 was used.

  Next, the safety valve mechanism 40 was connected to the relay tab 16 protruding from the open end of the battery can 20 by laser welding. Thereafter, the positive electrode lead 15 is bent in the direction of the center hole 18 so that the relay tab 16 and the end face of the battery element 10 are parallel to each other, and the tip of the relay tab 16 is bent approximately 180 ° and stored in the upper part of the battery can 20. After that, by crimping the battery can 20 through the gasket 50, the safety valve mechanism 40 and the battery lid 30 were fixed, and a battery was manufactured.

<Sample 2>
A battery was fabricated in the same manner as Sample 1 except that the thickness of the relay tab 16 was 250 μm and the width was 10 mm. The cross-sectional area of the relay tab 16 is 2.5 mm ² .

<Sample 3>
A battery was fabricated in the same manner as Sample 1 except that the thickness of the relay tab 16 was 100 μm and the width was 10 mm. The cross-sectional area of the relay tab 16 is 1 mm ² .

<Sample 4>
In the positive electrode lead 15 of the sample 1, as shown in FIG. 13A, the thickness of the positive electrode lead 15a positioned at the outermost peripheral portion when wound is 200 μm and the width is 5 mm. Further, the length of the positive electrode lead 15 a is longer than that of other positive electrode leads 15. The total cross-sectional area of the positive electrode lead 15 is 2.5 mm ² .

  Similarly, in the negative electrode lead 17 of Sample 1, among the plurality of negative electrode leads 17, the thickness of the negative electrode lead 17a positioned at the outermost periphery when wound was 200 μm and the width was 5 mm. Further, the length of the negative electrode lead 17 a is longer than that of other negative electrode leads 17. Using the positive electrode 11 and the negative electrode 12 obtained as described above, a battery element 10 as shown in FIG. 13B was obtained.

  Next, each of the positive electrode leads 15 led out from the end face of the battery element 10 was bent in the direction of the center hole 18 along the end face of the battery element 10 as shown in FIG. 14A. Thereafter, the positive electrode lead 15 was bent in a direction perpendicular to the end face of the battery element 10 at a position indicated by a dotted line indicated by an arrow A in FIG. 14 so as not to block the central hole 18.

  As shown in FIG. 14B, the bent positive lead 15 has a long positive lead 15a and does not protrude perpendicularly to the end face of the battery element 10. Therefore, the bent positive lead 15a is placed in the opposite direction. Folding was performed, and bending was performed again in the vicinity of the center hole 18 so that the positive electrode lead 15a was adjusted to protrude from the end face of the battery element 10 in the vertical direction.

  On the other hand, since the negative electrode lead 17 cannot be welded to the bottom of the battery can 20 when the negative electrode lead 17 is bent in the same manner as in the sample 1, as shown in FIG. After collecting the other negative electrode lead 17 at the position where the negative electrode lead 17a on the outer peripheral portion was led out, these connections were made. At this time, each of the negative electrode leads 17 other than the negative electrode lead 17a is once bent in the direction of the center hole 18 and then moved in the direction of the negative electrode lead 17a as shown by the dotted lines of arrows F and G in FIG. 15A. It was bent approximately 180 °.

  Subsequently, as shown in FIG. 15B, the other negative electrode lead 17 bent in the direction of the negative electrode lead 17a is further bent along the negative electrode lead 17a at a position overlapping with the negative electrode lead 17a, and then the negative electrode lead 17 Were connected by ultrasonic welding. Thereafter, as shown in FIG. 15C, the negative electrode lead 17 a was bent at a substantially right angle in the direction of the center hole 18.

  In the process of assembling the battery, the safety valve mechanism 40 was connected to the positive electrode lead 15 protruding from the open end of the battery can 20. A battery was fabricated in the same manner as Sample 1 except for the above.

<Sample 5>
In the sample 4, the positive electrode lead 15 is connected to the positive electrode lead 15a other than the positive electrode lead 15a in the direction of the positive electrode lead 15a located at the outermost peripheral portion of the battery element 10 in the same manner as the bending method of the negative electrode lead 17 shown in FIG. Then, the other positive electrode lead 15 was further bent along the positive electrode lead 15a at a position overlapping the positive electrode lead 15a. Thereafter, these positive electrode leads 15 were connected by ultrasonic welding.

  Subsequently, in order to prevent the positive electrode lead 15 and the constricted portion of the battery can 20 from coming into contact with each other when the battery can 20 is beaded, the positive electrode lead 15 is placed in the direction of the center hole 18 in the battery element. It was bent so as to be parallel to the end face of 10. After that, it was bent at a right angle so as to be perpendicular to the end face again in the vicinity of the center hole 18.

  A battery was fabricated in the same manner as Sample 4 except for the above.

<Sample 6>
In sample 1, the positive electrode lead 15 and the negative electrode lead 17 were all made the same length, and the battery element 10 was obtained.

  The positive electrode lead 15 led out from the end face of the obtained battery element 10 was connected by stopping with a bolt 31 provided by processing the safety valve mechanism 40 as shown in FIG. In addition, illustration of the gasket 50 is abbreviate | omitted in FIG.

  Similarly, the negative electrode lead 17 led out from the end face of the battery element 10 was connected by fastening with a bolt 32 provided by processing the bottom of the battery can 20 as shown in FIG.

  A battery was fabricated in the same manner as Sample 1 except for the above. In addition, although the safety valve mechanism 40 does not function in the battery of sample 6, there is no influence when an evaluation as described later is performed.

Evaluation was made as above battery, the number folding manner by (a) a positive electrode lead 15 below, the ratio of (b) DC resistance, (c) the capacity retention ratio, and (d) battery element occupying the cell volume Asked.

(A) Number of bendings of positive electrode lead 15 In order to evaluate the ease of manufacture of the batteries prepared in Samples 1 to 6, the number of bendings of the positive electrode lead 15 was compared. Here, the total number of times of bending of each positive electrode lead 15 between the battery element 10 and the safety valve mechanism 40 was determined.

(B) DC resistance The batteries prepared in Sample 1 to Sample 6 are in a semi-discharged state (that is, a state where the discharge depth is 50%), and the voltage and current are plotted after 5 seconds under each condition of 1C, 10C, and 30C The direct current resistance was calculated by obtaining the slope of. Here, relative comparison was performed with the battery of Sample 1 as 100. The depth of discharge indicates the ratio of the capacity taken out from the battery to the actual capacity.

(C) Capacity maintenance rate About the batteries produced in Samples 1 to 6, after carrying out constant current and constant voltage charging under conditions of a charging voltage of 4.2 V, a charging current of 1 C, and a charging time of 2.5 hours, a discharging current of 10 C, Discharging was performed at a final voltage of 3 V, and the initial capacity was measured. Further, charge and discharge were repeated in the same manner as when the initial capacity was determined, the discharge capacity after 500 cycles was measured, and the capacity retention rate with respect to the initial capacity was determined to evaluate the cycle characteristics.

(D) Ratio of battery element occupying battery volume For the batteries prepared in Samples 1 to 6, the ratio of battery element 10 occupying the battery volume was compared. Here, the comparison was performed with the battery of Sample 1 as 100.

  The evaluation results are shown in Table 1.

  As shown in Table 1, it was found that the batteries of samples 1 to 3 were easier to manufacture because the number of times the positive electrode lead 15 was bent was smaller than that of the batteries of samples 4 to 6. In addition, since the resistance can be reduced, the temperature of the battery can be reduced. Therefore, excellent results were obtained even with a capacity retention rate after 500 cycles. Furthermore, it turned out that it is excellent also in the ratio (space efficiency) of the battery element 10 to a battery volume.

  In addition, from Sample 1 to Sample 3, it was found that when the cross-sectional area of the relay tab 16 is larger than the total cross-sectional area of the positive electrode lead 15, the DC resistance value is reduced and the capacity retention rate is also improved.

  On the other hand, in Sample 4 and Sample 5, the number of times the positive electrode lead 15 was bent increased, the DC resistance increased, and the capacity retention rate also decreased. Further, it was found that in Sample 6 in which the positive electrode lead 15 and the negative electrode lead 17 are connected by bolts, the DC resistance increases, the capacity retention rate decreases, and the space efficiency decreases.

  From the above results, the plurality of positive leads 15 are bent in the direction of the center hole 18 of the battery element 10 and then bent near the center hole 18 so as not to block the center hole 18 to be connected to the relay tab 16. Further, the number of times of bending of the positive electrode lead 15 is small, and the positive electrode lead 15 can be easily connected to the safety valve mechanism 40 via the relay tab 16, so that the battery can be easily manufactured.

  In addition, since the positive electrode lead 15 and the negative electrode lead 17 can be connected to the safety valve mechanism 40 and the bottom of the battery can 20 without the need for parts such as bolts, space efficiency is also improved. Furthermore, it was found that a battery having low resistance and excellent cycle characteristics can be obtained.

  The present invention is not limited to the above-described embodiments of the present invention, and various modifications and applications are possible without departing from the spirit of the present invention. For example, the shape is not particularly limited, and the battery element may be accommodated in a square can.

  In the above-described embodiment, the case where the present invention is applied to a lithium ion secondary battery has been described. However, the present invention can also be applied to other nonaqueous electrolyte secondary batteries. In addition, the present invention may be applied not only to secondary batteries but also to primary batteries.

It is sectional drawing which shows an example of a structure of the battery by one embodiment of this invention. It is a perspective half view of an example of the component of the safety valve mechanism in the battery by one Embodiment of this invention. It is sectional drawing which shows an example of a structure of the open end part of the battery can of the battery by one Embodiment of this invention. FIG. 4 is a schematic diagram for explaining one lead-out of the positive electrode lead in the battery element according to the embodiment of the present invention. It is sectional drawing which shows an example of a structure of the bottom part of the battery can of the battery by one embodiment of this invention. It is the schematic which shows the positive electrode of the battery by one Embodiment of this invention, a negative electrode, and a battery element. It is the schematic which shows a state when the positive electrode lead is bent in the positive electrode of the battery by one Embodiment of this invention. It is the schematic for demonstrating welding with the positive electrode lead and relay tab of the battery by one Embodiment of this invention. It is the schematic for demonstrating the bending and welding of the negative electrode lead of the battery by one Embodiment of this invention. It is the schematic for demonstrating welding with the negative electrode lead of a battery and battery can by one Embodiment of this invention. It is the schematic for demonstrating welding with the positive electrode lead of a battery and safety valve by one Embodiment of this invention. It is the schematic for demonstrating the bending of the relay tab of the battery by one Embodiment of this invention. FIG. 6 is a schematic view showing a positive electrode, a negative electrode, and a battery element of a battery of Sample 4. It is the schematic which shows a state when the positive electrode lead of the battery of the sample 4 is bent. 6 is a schematic view for explaining bending of a negative electrode lead of a battery of Sample 4. FIG. 6 is a schematic diagram for explaining a configuration of a battery of Sample 5. FIG. It is sectional drawing which shows the conventional battery structure. It is the schematic for demonstrating the position where several electrode lead is derived | led-out in the end surface of the conventional battery element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 106 ... Battery element 11 ... Positive electrode 11a ... Positive electrode collector 11b ... Positive electrode active material layer 12 ... Negative electrode 12a ... Negative electrode collector 12b ... Negative electrode active material Layer 13 ··· Separator 14 ··· Center pin 15 ··· Positive electrode lead 16 ··· Relay tab 17 ··· Negative electrode lead 18 · · · center hole 20 · · · Battery can 30 · · · Battery lid 31 32 ... Bolt 40 ... Safety valve mechanism 41 ... Safety valve 42 ... Support holder 43 ... Insulating holder 44 ... Heat sensitive resistance element 45 ... Connection 50 ... Gasket 123 ..Electrode leads

Claims (10)

A battery element having a center hole penetrating both end faces, a positive electrode having an active material layer on a conductive substrate and a negative electrode having an active material layer on a conductive substrate wound through a separator;
A plurality of positive and negative lead leads respectively derived from both end faces of the battery element;
Electrolyte,
A battery can containing the battery element and the electrolyte, at least one end of which is opened; and
A battery lid and a safety valve for closing the open end of the battery can;
A relay tab connecting the positive electrode lead and the safety valve;
With
The plurality of positive leads are folded and overlapped in the direction of the central hole of the battery element, and are bent in the direction of the safety valve in the vicinity of the central hole so as not to block the central hole. A battery characterized by being connected. 2. The battery according to claim 1, wherein, when a circle having the center hole as a center is drawn, positions where the plurality of positive electrode leads are led are arranged within a central angle of 135 ° of the circle. . The battery according to claim 1, wherein a cross-sectional area of the relay tab is larger than a total cross-sectional area of the plurality of positive electrode leads. In the plurality of positive electrode leads, the length of the positive electrode lead derived from the inner periphery of the battery element is shorter than the length of the positive electrode lead derived from the outer periphery of the battery element. The battery according to claim 1. The battery according to claim 1, wherein the plurality of positive electrode leads and the relay tab are connected by ultrasonic welding. The plurality of negative electrode leads are folded and overlapped in the direction of the central hole of the battery element, and are bent in the direction of the battery can in the vicinity of the central hole so as not to block the central hole. The battery according to claim 1, wherein the battery is connected to the battery. The battery according to claim 6, wherein the plurality of negative electrode leads are bent in the direction of the battery can bottom in the vicinity of the center hole and connected by ultrasonic welding. 7. The battery according to claim 6, wherein, when a circle having the center hole as a center is drawn, the positions where the plurality of negative electrode leads are led out are arranged within a central angle of 135 ° of the circle. . In the plurality of negative electrode leads, the length of the negative electrode lead derived from the inner peripheral portion of the battery element is shorter than the length of the negative electrode lead derived from the outer peripheral portion of the battery element. The battery according to claim 6. The battery according to claim 6, wherein the plurality of negative electrode leads and the battery can are connected by resistance welding.

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