JP2012022955A - Secondary battery manufacturing method and secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a secondary battery manufacturing method.SOLUTION: The method comprises the steps of: forming an electrode group 6 by winding a positive electrode, a negative electrode, and a separator; housing the electrode group 6 in a cylindrical container 1; impregnating the electrode group 6 with a nonaqueous electrolyte; attaching a seal 3 to an opening of the cylindrical container 1 by inserting a positive electrode lead terminal 7 and a negative electrode lead terminal 8 into through holes 13 of the seal 3 so that a protrusion 7a and a protrusion 8a are held by the seal 3 in the through holes 13; and squeezing a side part 10 of the cylindrical container 1 so that a compressing load in the radial direction applied to the part of the seal 3 between the top 3p and the bottom 3q of the seal 3 along the direction of the height of the cylindrical container 1 increases.

Description

  The present invention relates to a method for manufacturing a secondary battery and a secondary battery.

  Secondary batteries are used in various portable devices such as notebook computers. In response to demands for long-time driving of portable devices and improvement of portability, secondary batteries are required to be further reduced in weight, improved in energy density, and improved in reliability. In recent years, a system using a secondary battery has been actively proposed for the purpose of protecting the global environment. For example, in the vehicle field, hybrid vehicles including a motor and an internal combustion engine and electric vehicles including only a motor are becoming widespread. In the field of power storage, in order to effectively use natural energy such as sunlight, a relatively large capacity power storage system using a secondary battery has been proposed.

  In lithium ion secondary batteries for portable devices, laminated aluminum foil containers and metal flat rectangular containers are widely used as containers for storing electrode plates. On the other hand, in consideration of the length of use period, severe use environment, large storage capacity, etc., in the secondary battery for the energy field, a metal cylindrical container is used as a container for storing the electrode plate group. Is influential.

  The metal cylindrical container has a structure disclosed in Patent Document 1 and Non-Patent Document 1, for example. That is, the cylindrical container is comprised by the bottomed container main body and the sealing board for closing the opening part of a container main body. The two lead terminals connected to the electrode plate group are welded to the container body and the sealing plate, respectively. The sealing plate also serves as a safety device and has a relatively complicated structure.

  Specifically, Non-Patent Document 1 discloses a sealing plate composed of parts such as an insulating ring, a gasket, a PTC (Positive Temperature Coefficient) element, and a rupture.

Japanese Patent Laid-Open No. 11-86868 Yoshiyuki Masao and Akiya Ozawa, “Lithium-ion Secondary Batteries-Materials and Applications”, 2nd edition, Nikkan Kogyo Shimbun, January 27, 2001, p. 175-176

  As can be understood from Patent Document 1 and Non-Patent Document 1, the number of parts of a metal cylindrical container is relatively large. This hinders cost reduction and productivity improvement of the secondary battery.

  Moreover, the following problems also exist in the secondary battery using a metal cylindrical container. Various methods such as laser welding, resistance welding, spot welding, or ultrasonic welding are employed to weld the lead terminal to the container body or the sealing plate. Regardless of which welding method is employed, it is necessary to precisely manage the welding conditions and electrode settings for each welding site due to the relatively narrow range of stable welding conditions. Even if such precise control is performed, for example, if the welding current is excessive, a hole is formed in the welding part such as a lead terminal, or the metal melted during welding becomes a metal fume due to the spark of sputtering. Or scatter. The scattered metal (metal powder) is mixed as a foreign substance in the container and can cause an internal short circuit of the battery. Thus, the conventional secondary battery manufacturing process includes a welding process, and in the welding process, it is necessary to precisely manage the welding conditions. This hinders reduction in the cost of the secondary battery.

  In view of the above circumstances, an object of the present invention is to provide an improved manufacturing method of a secondary battery and a secondary battery manufactured by the method.

That is, the present invention
A positive electrode having a positive electrode lead terminal having a protrusion on the open end side, a negative electrode having a negative electrode lead terminal having a protrusion on the open end side, and a separator disposed between the positive electrode and the negative electrode; Forming a group of electrodes by winding
Storing the electrode group in a metal cylindrical container;
Impregnating the electrode group with a non-aqueous electrolyte; and
The protruding portion of the positive electrode lead terminal and the protruding portion of the negative electrode lead terminal are held in the sealing body in each through hole in each through hole of the sealing body having elasticity through two through holes. Inserting the positive electrode lead terminal and the negative electrode lead terminal as described above, and attaching the sealing body to the opening of the cylindrical container;
The side part of the cylindrical container increases the radial compressive load applied to the sealing body between the upper surface of the sealing body and the lower surface of the sealing body with respect to the height direction of the cylindrical container. Caulking process,
A method for manufacturing a secondary battery is provided.

In another aspect, the present invention provides:
A metal cylindrical container;
A wound electrode group having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and housed in the cylindrical container;
A sealing body fixed to the opening of the cylindrical container,
The electrode group further includes a positive electrode lead terminal connected to the positive electrode and a negative electrode lead terminal connected to the negative electrode,
The sealing body has two through holes and is made of an elastic material,
Each of the positive electrode lead terminal and the negative electrode lead terminal has a protruding portion on the open end side, and each of the sealing bodies is held by the sealing body in each through hole. Inserted in the through hole,
The side of the cylindrical container protrudes in the direction toward the central axis of the electrode group between the upper surface of the sealing body and the lower surface of the sealing body with respect to the height direction of the cylindrical container. Provided is a secondary battery provided with a caulking portion.

  According to the present invention, a sealing body made of an elastic material is used as a member for closing an opening of a metal cylindrical container. The positive electrode lead terminal and the negative electrode lead terminal extend to the outside of the cylindrical container through two through holes formed in the sealing body. According to such a structure, it is easy to simplify the manufacturing process of the secondary battery. Specifically, it is not necessary to weld the lead terminal to the cylindrical container or the sealing body. Since the welding process can be omitted, various problems such as a decrease in the reliability of the secondary battery and a deterioration in the working environment due to the metal powder remaining in the cylindrical container are unlikely to occur.

  According to the present invention, each of the positive electrode lead terminal and the negative electrode lead terminal has a protrusion on the open end side. Due to the pressing force acting on the sealing body during caulking, the positive electrode lead terminal and the negative electrode lead terminal respectively bite into the sealing body in the through holes, and each lead terminal is joined to the sealing body. Thereby, an electrode group can be fixed with respect to a cylindrical container via a positive electrode lead terminal, a negative electrode lead terminal, and a sealing body. Further, the protrusions provided on the positive electrode lead terminal and the negative electrode lead terminal receive an elastic force from the sealing body in the through hole and are held by the sealing body. In other words, the through hole is blocked by the protrusion. Thereby, the permeation | transmission of the water | moisture content from the exterior into a cylindrical container can be prevented, and the reliability of a secondary battery can be improved. In addition, since the protrusions provided on the positive electrode lead terminal and the negative electrode lead terminal respectively bite into the sealing body in the through holes, the electrode group is transferred to the cylindrical container via the positive electrode lead terminal, the negative electrode lead terminal, and the sealing body. The effect of fixing against can be strengthened.

  Further, even if a load is applied to each lead terminal based on the weight of the electrode group, the mechanical stress on each lead terminal can be suppressed because the protrusion is firmly held in the through hole. Accordingly, the position of the lead terminal relative to the sealing body can be prevented, thereby allowing moisture permeation into the cylindrical container based on the position shift of the lead terminal, that is, through a minute gap between the through hole and the lead terminal. Water permeation into the inside of the cylindrical container can be prevented.

  In addition, each process included in the manufacturing method of the said invention may be implemented in said order, and may be implemented by changing the order of one process and another process.

Sectional drawing of the secondary battery which concerns on one Embodiment of this invention. The exploded perspective view of the electrode group of the secondary battery shown in FIG. Partial sectional view of a secondary battery according to a modification Manufacturing process diagram of the secondary battery shown in FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to these.

  As shown in FIG. 1, the secondary battery 100 according to the present embodiment includes a metal cylindrical container 1, an electrode group 6 housed in the cylindrical container 1, and a seal fixed to the opening of the cylindrical container 1. A stop 3 is provided. The secondary battery 100 is typically a lithium ion secondary battery.

  As shown in FIG. 2, the electrode group 6 includes a positive electrode 20, a positive electrode lead terminal 7, a negative electrode 25, a negative electrode lead terminal 8, and two separators 24. The separators 24 are respectively disposed between the positive electrode 20 and the negative electrode 25. The positive electrode lead terminal 7 and the negative electrode lead terminal 8 are connected to the positive electrode 20 and the negative electrode 25, respectively. The positive electrode 20, the negative electrode 25, and the separator 24 are wound around a winding core 29. Thereby, the electrode group 6 has a cylindrical shape as a whole.

  As shown in FIG. 1, two through holes 13 are formed in the sealing body 3. The through hole 13 has a diameter smaller than the diameter of the positive electrode lead terminal 7 (or the negative electrode lead terminal 8). The positive electrode lead terminal 7 is inserted into the through hole 13 of the sealing body 3 so that the projection 7 a is held by the sealing body 3 in one of the two through holes 13. Similarly, the negative electrode lead terminal 8 is inserted into the through hole 13 of the sealing body 3 so that the protruding portion 8 a is held by the sealing body 3 in the other of the two through holes 13. That is, each of the positive electrode lead terminal 7 and the negative electrode lead terminal 8 extends through the through hole 13 to the outside of the cylindrical container 1. In the present embodiment, the length of the positive electrode lead terminal 7 matches the length of the negative electrode lead terminal 8 with respect to the height direction of the cylindrical container 1. Further, with respect to the height direction, the position of the protrusion 7a coincides with the position of the protrusion 8a.

  The side portion 1 a of the cylindrical container 1 is positioned in the direction toward the central axis of the electrode group 6 between the upper surface 3 p of the sealing body 3 and the lower surface 3 q of the sealing body 3 with respect to the height direction of the cylindrical container 1. A protruding caulking portion 10 is provided. The caulking portion 10 is formed along the circumferential direction of the cylindrical container 1 so as to have an annular shape. According to this configuration, a uniform compressive load can be applied to the sealing body 3 in the circumferential direction.

  In the present embodiment, the caulking portion 10 is provided between the lower end of the protruding portion 7a (and 8a) and the lower surface 3q of the sealing body 3 in the height direction. That is, the protrusion 7a (and 8a) is located at a position closer to the opening of the cylindrical container 1 than a position where the most caulking effect can be obtained. According to such a configuration, it is possible to fix the positive electrode lead terminal 7 to the sealing body 3 at two locations of the caulking portion 10 and the protruding portion 7a in the height direction. Similarly, it is possible to fix the negative electrode lead terminal 8 to the sealing body 3 at two locations of the caulking portion 10 and the protruding portion 8a. As a result, the effect of supporting the electrode group 6 is further strengthened. Further, the effect of preventing moisture permeation can be enhanced.

  In the present embodiment, the most depressed position H1 of the caulking portion 10 is located between the lower ends of the protruding portions 7a and 8a and the lower surface 3q of the sealing body 3 in the height direction. Accordingly, the maximum compressive load is applied to the sealing body 3 at a position slightly below the protrusions 7a and 8a. In the present embodiment, a part of the caulking portion 10 overlaps the protruding portions 7a and 8a in the height direction. However, with respect to the height direction, the positions of the caulking portion 10 and the protruding portions 7a and 8a can be defined so that the caulking portion 10 does not overlap the protruding portions 7a and 8a.

  The open end 12 of the cylindrical container 1 is bent in a U shape. The open end 12 bent in a U-shape is in contact with the upper surface 3 p of the sealing body 3, thereby applying a load in a direction of pushing into the cylindrical container 1 to the sealing body 3. On the inner side of the cylindrical container 1, the inner peripheral surface of the cylindrical container 1 between the lower surface 3 q of the sealing body 3 and the bottom surface (inner bottom surface) of the cylindrical container 1 in the height direction of the cylindrical container 1. And a protrusion 17 that narrows the gap between the electrode group 6 and the outer peripheral surface of the electrode group 6. In the present embodiment, the convex portion 17 is slightly in contact with the electrode group 6 so as not to deform the electrode group 6. The convex portion 17 has an annular shape surrounding the electrode group 6 in the circumferential direction.

  Secondary batteries are often used under high temperature conditions such as in mid-summer cars as well as normal use. In this case, the internal pressure of the secondary battery may increase. In addition, the nonaqueous electrolyte secondary battery performs charge and discharge by putting in and out nonaqueous electrolyte ions in the crystals of the positive electrode material and the negative electrode material. At that time, since the crystal may be expanded and contracted, the electrode group is deformed. When the electrode group is deformed, the state of the powder contained in the electrode mixture is deformed, and the internal resistance may increase or the distance between the positive electrode and the negative electrode may increase. Deteriorates. When the convex portion 17 is provided as in the present embodiment, not only the electrode group 6 can be fixed to the cylindrical container 1 but also the deformation of the electrode group 6 can be suppressed. Therefore, the characteristics of the secondary battery 100 are maintained well over a long period of time.

  Further, when the convex portion 17 is formed in an annular shape, a uniform holding force can act on the electrode group 6 in the circumferential direction. Thereby, the effect which suppresses a deformation | transformation of the electrode group 6 further increases. Since the central axis of the electrode group 6 can coincide with the central axis of the cylindrical container 1, mechanical stress is hardly applied to the lead terminals 7 and 8. Furthermore, the durability of the cylindrical container 1 against an increase in internal pressure and external pressure is also improved.

  In the present embodiment, the sealant 15 is filled in a portion of the contact interface between the positive electrode lead terminal 7 and the sealing body 3 that is close to the opening of the cylindrical container 1 with reference to the position where the protrusion 7 a is held. Has been. Similarly, in the contact interface between the negative electrode lead terminal 8 and the sealing body 3, a portion close to the opening of the cylindrical container 1 is filled with the sealing agent 15 with reference to the position where the protrusion 8 a is held. . The sealant 15 plays a role of preventing leakage and evaporation of the electrolyte to the outside and a role of preventing moisture from entering the inside of the cylindrical container 1 from the outside. According to the sealing agent 15, the function of the lead terminals 7 and 8 supporting the electrode group 6 can be further enhanced.

  Note that another member such as an insulating sheet may be provided between the space at the bottom of the cylindrical container 1, that is, between the bottom of the cylindrical container 1 and the electrode group 6. Similarly, another member such as an insulating sheet may be provided between the lower surface 3 q of the sealing body 3 and the electrode group 6.

  Next, each component will be described in detail.

<< Cylindrical container >>
The cylindrical container 1 is a metal container having a bottom and an opening. As a material of the cylindrical container 1, metals such as aluminum and aluminum alloy can be suitably used from the viewpoint of lightness and workability. An aluminum alloy to which a small amount of an element such as Cu, Mn, or Si is added is preferable because the caulking strength can be relatively easily increased.

<< Encapsulant >>
The sealing body 3 is made of an elastic material. Specifically, the sealing body 3 is made of a rubber-elastic material (elastomer) and has a cylindrical shape. The diameter of the sealing body 3 is slightly larger than the diameter of the opening of the cylindrical container 1. As a material of the sealing body 3, ethylene propylene diene rubber (EPDM), isobutylene isoprene rubber (IIR), butadiene styrene rubber (SBR), or the like can be used.

<< Positive electrode >>
As shown in FIG. 2, the positive electrode 20 includes a positive electrode current collector 21 and a positive electrode active material layer 22 provided on one or both surfaces of the positive electrode current collector 21. The positive electrode active material layer 22 is composed of, for example, a positive electrode active material, a binder, and a conductive additive.

  The positive electrode current collector 21 is a conductive sheet-like member, and is typically made of a metal foil. Instead of the metal foil, a member having a large number of holes (metal mesh, punching metal, expanded metal) can also be used. As a material of the positive electrode current collector 21, a metal such as aluminum or an aluminum alloy can be suitably used.

Examples of the positive electrode active material include manganese dioxide (MnO ₂ ), lithium manganese composite oxide (eg, Li _x Mn ₂ O ₄ or Li _x MnO ₂ ), lithium nickel composite oxide (eg, Li _x NiO ₂ ), and lithium cobalt composite oxide. objects (e.g. Li _x CoO _2), lithium nickel cobalt composite oxide (e.g., _{LiNi 1-y Co y O 2} ), lithium manganese cobalt composite oxides (e.g., _{Li x Mn y Co 1-y} O 2), spinel type lithium Oxides such as manganese nickel composite oxide (Li _x Mn _{2 -y} Ni _y O ₄ ) and lithium phosphorus oxide having an olivine structure (Li _x FePO ₄ ) can be used. In the above chemical formula, “x” and “y” may each be a value in the range of 0-1.

  Preferred positive electrode active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, lithium nickel cobalt composite oxide, spinel type lithium manganese nickel composite oxide, lithium manganese cobalt composite oxide, lithium phosphoric acid Iron. These have a charge / discharge potential of, for example, 3.0 V or more and 5.0 V or less with respect to the potential of metallic lithium.

  As the conductive agent, carbon materials such as acetylene black, carbon black, and graphite can be used. As the binder, resin materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), carboxymethylcellulose (CMC), fluororubber, and styrene butadiene rubber (SBR) can be used.

<< Negative electrode >>
The negative electrode 25 includes a negative electrode current collector 26 and a negative electrode active material layer 27 provided on one or both surfaces of the negative electrode current collector 26. The negative electrode active material layer 27 is composed of, for example, a negative electrode active material, a binder, and a conductive additive.

  The negative electrode current collector 26 is also a sheet-like member having conductivity, and is typically composed of a metal foil. Instead of the metal foil, a member having a large number of holes (metal mesh, punching metal, expanded metal) can also be used. As a material of the negative electrode current collector 26, metals such as nickel, nickel alloy, copper, copper alloy, aluminum, aluminum alloy can be suitably used.

Examples of the negative electrode active material include lithium metal, lithium alloy, lithium titanium composite oxide (for example, Li ₄ Ti ₅ O ₁₂ ), a carbon material that can occlude and release lithium ions, and a material that can form an alloy with lithium (so-called alloy-based active material). Substance). A typical carbon material is graphite. Examples of the alloy-based active material include tin, tin alloy, silicon, and silicon alloy. From the viewpoint of charge / discharge efficiency and cycle life, a carbon material or a lithium titanium composite oxide can be preferably used.

  As the binder and the conductive assistant, the same materials as those of the positive electrode 20 can be used.

  When the negative electrode 25 (specifically, the negative electrode active material layer 27) contains a negative electrode active material having a noble potential of 1.0 V or more with respect to the potential of metallic lithium, the negative electrode current collector 26 is preferably aluminum or an aluminum alloy. Made of. According to this configuration, the elution of the cylindrical container 1 can be prevented even when the negative electrode 25 touches the aluminum cylindrical container 1. In other words, according to the said structure, use of the cylindrical container 1 made from aluminum is permitted. The aluminum cylindrical container 1 contributes to the weight reduction of the secondary battery 100.

As a negative electrode active material having a noble potential of 1.0 V or more with respect to the potential of metallic lithium, a composite oxide containing lithium and titanium can be given. Specifically, lithium titanate represented by the chemical formula Li _{4 + x} Ti ₅ O ₁₂ (0 ≦ x ≦ 3) and having a spinel structure can be given.

<< Separator >>
As the separator 24, a porous film, a nonwoven fabric, or the like can be used. Examples of the porous film include those made of polyethylene or polypropylene. Examples of the nonwoven fabric include those made of cellulose or polyvinyl alcohol (PVA).

<< Non-aqueous electrolyte >>
The positive electrode 20, the negative electrode 25, and the separator 24 are impregnated with a nonaqueous electrolyte. Examples of the non-aqueous electrolyte include a liquid non-aqueous electrolyte containing an electrolyte and an organic solvent. As the organic solvent, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), and vinylene carbonate (VC) can be used. Chain carbonates such as dimethyl carbonate (DMC), methyl ethyl carbonate (MEC) and diethyl carbonate (DEC), cyclic ethers such as tetrahydrofuran (THF) and 2 methyltetrahydrofuran (2MeTHF), chain ethers such as dimethoxyethane (DME) Acetonitrile (AN), sulfolane (SL), etc. can also be used. These organic solvents can be used alone or in the form of a mixture of two or more.

Examples of the electrolyte include lithium salts such as lithium perchlorate (LiClO ₄ ), lithium hexafluorophosphate (LiPF ₆ ), and lithium tetrafluoroborate (LiBF ₄ ). From the viewpoint of chemical stability and high dielectric constant, it is preferable to use lithium hexafluorophosphate (LiPF ₆ ) as the main electrolyte. The “main electrolyte” means an electrolyte that is contained most in a molar ratio. The electrolyte is dissolved in the organic solvent at a concentration of 0.5 to 2.0 mol / L, for example.

<< Lead terminal >>
The positive electrode lead terminal 7 includes a first portion fixed to the positive electrode current collector 21, a second portion extending outside the cylindrical container 1 through the through hole 13 of the sealing body 3, and a second portion And a projecting portion 7a provided on the surface. That is, the positive electrode lead terminal 7 has the protrusion 7a on the open end side. The first part is a part formed in a plate shape so as to be fixed to the positive electrode current collector 21 by welding or the like. The second portion is a rod-shaped portion having a constant diameter. “The diameter of the lead terminal” represents the diameter of the second portion. The protruding portion 7a is a portion protruding from the second portion toward the outside in the radial direction. That is, the protrusion 7a has a diameter larger than the diameter of the second portion.

  In the present embodiment, when viewed from a direction perpendicular to the height direction of the cylindrical container 1, the protrusion 7 a has a rectangular shape. When viewed from the axial direction of the positive electrode lead terminal 7, the protrusion 7 a has a circular shape. These structures are also adopted for the negative electrode lead terminal 8. In the present embodiment, each of the lead terminals 7 and 8 has only one protrusion 7a and 8a. However, a plurality of protrusions may be provided on one lead terminal. The diameter of the second part is, for example, in the range of 0.5 to 5 mm. Each diameter of the projections 7a and 8a is, for example, in the range of 0.6 to 7 mm. The inner diameter of the through hole 13 of the sealing body 3 is, for example, in the range of 0.2 to 4.9 mm.

  In the modification shown in FIG. 3, the protrusion 7 b of the positive electrode lead terminal 7 and the protrusion 8 b of the negative electrode lead terminal 8 are respectively cylindrical container 1 when viewed from a direction perpendicular to the height direction of the cylindrical container 1. It has a trapezoidal shape including a short side located on the opening side and a long side located on the bottom side of the cylindrical container 1. When the protrusions 7b and 8b having such shapes are provided, the lead terminals 7 and 8 can be inserted into the through hole 13 of the sealing body 3 relatively smoothly. Therefore, workability when assembling the secondary battery 100 is improved. Will improve. Moreover, the improvement of the function which supports the electrode group 6 can also be expected.

  As the material of the lead terminals 7 and 8, metals such as aluminum, aluminum alloy, nickel, nickel alloy, copper, copper alloy, and stainless steel can be used.

<< Sealant >>
As the sealant 15, use is made of pitches such as asphalt and coal tar, mixtures of pitches with other materials (mineral oil, silicone rubber, etc.), materials containing elastomers such as styrene butadiene rubber and butadiene rubber as main components. it can. The “main component” means a component that is contained most in mass ratio. In addition, as shown in the modification of FIG. 3, the sealing agent 15 may be filled under the projecting portions 7a and 8b. That is, in the contact interface between the positive electrode lead terminal 7 and the sealing body 3, the portion near the electrode group 6 is filled with the sealing agent 15 with reference to the position where the protrusion 7 b (or 7 a) is held. Also good. Similarly, in the contact interface between the negative electrode lead terminal 8 and the sealing body 3, a portion close to the electrode group 6 is filled with the sealing agent 15 with reference to the position where the protruding portion 8 b (or 8 a) is held. Also good. According to such a configuration, moisture permeation into the cylindrical container 1 can be more reliably prevented.

  Next, a method for manufacturing the secondary battery shown in FIG. 1 will be described.

  As shown in FIG. 4, first, the positive electrode 20 and the negative electrode 25 are produced. The positive electrode 20 and the negative electrode 25 can be produced according to a known method. Specifically, a mixture containing an active material, a conductive additive, a binder and a solvent is applied to a long current collector, and the applied mixture is dried so that a mixture layer is formed. Thereafter, when the mixture layer and the current collector are pressed, strip-shaped electrodes (the positive electrode 20 and the negative electrode 25) are obtained (STEP 1). The positive electrode lead terminal 7 and the negative electrode lead terminal 8 are fixed to the positive electrode 20 and the negative electrode 25 by welding or the like, respectively.

  Next, the positive electrode 20, the negative electrode 25, and the separator 24 are wound to form the electrode group 6 (STEP 2). Next, the electrode group 6 is accommodated in the cylindrical container 1 (STEP 3). Next, the electrode group 6 is impregnated with a non-aqueous electrolyte (STEP 4). The step of impregnating the electrode group 6 with the nonaqueous electrolytic solution may be performed at any stage as long as the sealing body 3 is not attached to the cylindrical container 1.

  In order to easily store the electrode group 6, the diameter of the opening of the cylindrical container 1 is larger than the diameter of the bottom of the cylindrical container 1 before the secondary battery 100 is assembled. That is, the side part 1a of the cylindrical container 1 is gently tapered. In this case, it is desirable to perform drawing processing (diameter reduction processing) of the side portion 1a of the cylindrical container 1 after the electrode group 6 is stored. Thereby, the dimension of the cylindrical container 1 can be adjusted to a desired dimension.

  Next, the side part 1a of the cylindrical container 1 is caulked (STEP 5). Thereby, when the sealing body 3 is attached to the cylindrical container 1, the sealing body 3 between the upper surface 3 p of the sealing body 3 and the lower surface 3 q of the sealing body 3 in the height direction of the cylindrical container 1. The caulking portion 10 is formed to increase the radial compressive load applied to the.

  In addition, after the electrode group 6 is stored in the cylindrical container 1, a groove is formed in the outer peripheral surface of the cylindrical container 1 so as to narrow a gap between the inner peripheral surface of the cylindrical container 1 and the outer peripheral surface of the electrode group 6. The convex part 17 is provided inside the cylindrical container 1 by forming. Although the convex part 17 may contact the electrode group 6, it is desirable that the convex part 17 does not press the electrode group 6 from the viewpoint of the uniformity of the charge / discharge reaction, and that the convex part 17 does not deform the electrode group 6.

  In order to avoid applying excessive force to the lead terminals 7 and 8, the structure for preventing the electrode group 6 from moving in the cylindrical container 1 has a great role to play. In the present embodiment, the protrusions 7a and 8a of the lead terminals 7 and 8, the caulking part 10, and the convex part 17 are employed as such a structure. In particular, metals such as cobalt and manganese are often used for the electrode group 6, and the electrode group 6 tends to be heavy. In this case, the benefits provided by the structure are even greater.

  As with the caulking portion 10, the convex portion 17 can also be formed by caulking. Moreover, it is preferable to form a groove along the circumferential direction of the cylindrical container 1 so that the convex part 17 has an annular shape. Thereby, a uniform holding force can be applied in the circumferential direction of the electrode group 6.

  Next, the sealing body 3 is attached to the opening of the cylindrical container 1 (STEP 6). The positive electrode lead terminal 7 and the negative electrode lead terminal 8 are inserted into the respective through holes 13 of the sealing body 3 such that the protruding portions 7 a and the protruding portions 8 a are held by the sealing body 3 in the respective through holes 13. The sealing body 3 into which the lead terminals 7 and 8 are inserted is attached to the opening of the cylindrical container 1.

  After the sealing body 3 is mounted, a portion of the contact interface (micro gap) between the positive electrode lead terminal 7 and the sealing body 3 that is close to the opening of the cylindrical container 1 with reference to the position where the protrusion 7a is held. Is filled with sealant 15. For example, a dispenser having a thin tip can be used for filling the sealant 15. Similarly, the sealing agent 15 is filled in a portion of the contact interface between the negative electrode lead terminal 8 and the sealing body 3 that is close to the opening of the cylindrical container 1 with reference to the position where the protrusion 8 a is held. Thereby, the clearance gap between the lead terminals 7 and 8 and the through-hole 13 can be sealed reliably.

  Finally, the open end 12 is bent into a U shape so that a compressive load is applied to the upper surface 3p of the sealing body 3 (STEP 7). The opening end 12 can be bent by caulking. By performing the above steps, the secondary battery 100 shown in FIG. 1 is obtained. The caulking portion 10 may be formed after the sealing body 3 is attached to the opening of the cylindrical container 1. In this case, since the process of bending the open end 12 and the process of forming the caulking portion 10 can be performed simultaneously or continuously, an improvement in productivity can be expected. Similarly, the convex portion 17 may be formed after the sealing body 3 is attached to the opening of the cylindrical container 1.

  The method described above does not include a step of welding the lead terminals 7 and 8 to the cylindrical container 1 or the like. Accordingly, various problems such as a decrease in the reliability of the secondary battery and a deterioration in the working environment due to the generation of metal powder in the welding process and the remaining metal powder in the container are unlikely to occur. In addition, since the method of the present embodiment does not include processing that requires heating, problems such as distortion due to heating hardly occur in the electrode group 6.

  Moreover, the lithium secondary battery manufactured by the method described in this embodiment has high reliability because mechanical stress on the lead terminals and moisture permeation into the container are suppressed.

  The present invention can be advantageously applied to a secondary battery for the energy field, for example, a secondary battery for general household use.

DESCRIPTION OF SYMBOLS 1 Cylindrical container 3 Sealing body 6 Electrode group 7 Positive electrode lead terminal 8 Negative electrode lead terminal 7a, 7b, 8a, 8b Protrusion part 10 Caulking part 13 Through-hole 15 Sealant 17 Protrusion part 20 Positive electrode 24 Separator 25 Negative electrode 100 Secondary battery

Claims (12)

A positive electrode having a positive electrode lead terminal having a protrusion on the open end side, a negative electrode having a negative electrode lead terminal having a protrusion on the open end side, and a separator disposed between the positive electrode and the negative electrode; Forming a group of electrodes by winding
Storing the electrode group in a metal cylindrical container;
Impregnating the electrode group with a non-aqueous electrolyte; and
The protruding portion of the positive electrode lead terminal and the protruding portion of the negative electrode lead terminal are held in the sealing body in each through hole in each through hole of the sealing body having elasticity through two through holes. Inserting the positive electrode lead terminal and the negative electrode lead terminal as described above, and attaching the sealing body to the opening of the cylindrical container;
The side part of the cylindrical container increases the radial compressive load applied to the sealing body between the upper surface of the sealing body and the lower surface of the sealing body with respect to the height direction of the cylindrical container. Caulking process,
A method for manufacturing a secondary battery, comprising:   The method for manufacturing a secondary battery according to claim 1, wherein a side portion of the cylindrical container is caulked between a lower end of the protruding portion and a lower surface of the sealing body with respect to a height direction of the cylindrical container.   After the electrode group is stored in the cylindrical container, a groove is formed in the outer peripheral surface of the cylindrical container so as to narrow a gap between the inner peripheral surface of the cylindrical container and the outer peripheral surface of the electrode group. The method for manufacturing a secondary battery according to claim 1, further comprising a step of providing a convex portion inside the cylindrical container.   The method for manufacturing a secondary battery according to claim 3, wherein the groove is formed along a circumferential direction of the cylindrical container so that the convex portion has an annular shape.   Of the contact interface between the positive electrode lead terminal and the sealing body and the contact interface between the negative electrode lead terminal and the sealing body, the opening of the cylindrical container is based on the position where the protrusion is held. The manufacturing method of the secondary battery of any one of Claims 1-4 which further includes the process of filling the sealing agent in the part close | similar to a part. The cylindrical container is made of aluminum or aluminum alloy;
The method for producing a secondary battery according to claim 1, wherein the negative electrode includes a negative electrode active material having a noble potential of 1.0 V or more with respect to the potential of metallic lithium. A metal cylindrical container;
A wound electrode group having a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and housed in the cylindrical container;
A sealing body fixed to the opening of the cylindrical container,
The electrode group further includes a positive electrode lead terminal connected to the positive electrode and a negative electrode lead terminal connected to the negative electrode,
The sealing body has two through holes and is made of an elastic material,
Each of the positive electrode lead terminal and the negative electrode lead terminal has a protruding portion on the open end side, and each of the sealing bodies is held by the sealing body in each through hole. Inserted in the through hole,
The side of the cylindrical container protrudes in the direction toward the central axis of the electrode group between the upper surface of the sealing body and the lower surface of the sealing body with respect to the height direction of the cylindrical container. A secondary battery provided with a caulking portion.   The secondary battery according to claim 7, wherein the caulking portion is provided between a lower end of the protruding portion and a lower surface of the sealing body in the height direction.   Inside the cylindrical container, between the lower surface of the sealing body and the bottom surface of the cylindrical container in the height direction of the cylindrical container, the inner peripheral surface of the cylindrical container and the outer periphery of the electrode group The secondary battery according to claim 7, wherein a convex portion that narrows a gap between the surface and the surface is provided.   The secondary battery according to claim 9, wherein the convex portion has an annular shape surrounding the electrode group in a circumferential direction.   Of the contact interface between the positive electrode lead terminal and the sealing body and the contact interface between the negative electrode lead terminal and the sealing body, the opening of the cylindrical container is based on the position where the protrusion is held. The secondary battery according to claim 7, further comprising a sealant filled in a portion close to the portion.   The protrusions of the positive electrode lead terminal and the protrusions of the negative electrode lead terminal are respectively positioned on the opening side of the cylindrical container when viewed from a direction perpendicular to the height direction of the cylindrical container. The secondary battery according to claim 7, wherein the secondary battery has a trapezoidal shape including a short side and a long side located on a bottom side of the cylindrical container.

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