JP4436591B2 - Manufacturing method of secondary battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process for the production of secondary batteries.
[0002]
[Prior art]
The secondary battery is manufactured by separately manufacturing an outer can and an electrode body and pushing the electrode body into a cylindrical outer can. In the outer can, the electrolytic solution is injected after the electrode body is inserted. The electrolytic solution is injected from a liquid injection hole provided in the sealing plate by fixing the sealing plate to the opening of the outer can, or from the opening of the outer can. After injecting the electrolytic solution, the injection hole of the sealing plate is airtightly closed or the opening of the outer can is closed. The electrode body is manufactured by insulating and laminating a positive electrode and a negative electrode with a separator. The most common electrode body is a spiral electrode body formed by laminating an elongated positive electrode and a negative electrode with a separator interposed therebetween, and winding this. However, there are some in which a plurality of positive electrodes and negative electrodes are laminated with a separator interposed therebetween. The electrode body having this structure is inserted into an outer can formed into a cylindrical shape. The electrode body is manufactured to have an outer shape that can be smoothly inserted into the outer can. Since the electrode body specifies the charge / discharge capacity of the battery, the electrode body is manufactured as large as possible in order to increase the charge / discharge capacity. However, if it is too large, it will not be able to be inserted smoothly into the outer can, so it will be manufactured to the maximum size that can be inserted smoothly. The electrode body that can be smoothly inserted into the outer can moves inside the outer can while being put in the outer can.
[0003]
The electrode body placed in the outer can has the positive electrode and the negative electrode connected to the electrode terminals of the outer can via electrode leads. Since the secondary battery with this structure cannot have a structure in which the electrode surface or lead surface is completely insulated, if the electrode body moves inside the outer can, the electrode is deformed and the separator is broken to cause an internal short circuit. In this case, the current collector plate attached to take out the current from the electrode body is cut and the battery becomes unusable. For this reason, it is important to fix the electrode body placed in the outer can so as not to move. In the conventional secondary battery, in order to stop the movement of the electrode body, a spacer is provided between the electrode body and the sealing plate, or a protrusion that protrudes on the inner surface is provided along the upper edge of the electrode body. ing.
[0004]
[Problems to be solved by the invention]
The structure in which the movement of the electrode body is stopped by the spacer or the protrusion cannot always stop the movement of the electrode body in various usage environments. For example, when the secondary battery falls and receives a large impact, the impact may cause the electrode body to be displaced within the outer can. In particular, in secondary batteries that are not housed in a case with a buffering effect, the impact of the drop acts directly on the outer can, so the end of the electrode body is crushed by spacers and protrusions, creating a space for the electrode body to move. The built-in electrode body may be displaced.
[0005]
The present invention has been developed for the purpose of solving such drawbacks. An important object of the present invention is to provide a manufacturing method of the secondary batteries can be effectively prevented the displacement of the electrode body due to the impact. In particular, the present invention is very simple structure, to provide a method for manufacturing a secondary batteries that can effectively prevent displacement of the electrode body structure can be inexpensively mass-produced.
[0006]
[Means for Solving the Problems]
In the secondary battery manufactured by the method of the present invention, the electrode body 2 is put in an outer can which is hermetically sealed. When the secondary battery is heated between the surface of the electrode body 2 and the inner surface of the outer can, the frictional force increasing material increases the surface friction force between the electrode body 2 and the outer can. 16 is provided. The frictional force increasing material 16 is heated to a temperature that does not deteriorate the battery performance, and the electrode body 2 is adhered and fixed to the inner surface of the outer can.
[0007]
The electrode body 2 is a spiral electrode body formed by winding a positive electrode and a negative electrode with a separator interposed therebetween, and a terminal edge of the spiral electrode body can be bonded with a frictional force increasing material 16. The frictional force increasing material 16 fixes the spiral electrode body in a wound state and fixes the electrode body 2 to the inner surface of the outer can. As the frictional force increasing material 16, a material that increases the frictional force when heated to 70 to 110 ° C. can be used.
[0008]
Furthermore, the manufacturing method of the secondary battery of this invention manufactures a secondary battery by sealing the opening part of an armored can airtightly, after putting the electrode body 2 and electrolyte solution in an armored can. In this manufacturing method, before the electrode body 2 is put in the outer can, the frictional force increasing material 16 that increases the adhesive force when attached to the surface of the electrode body 2 is heated to a temperature that does not deteriorate the battery performance. After putting the electrode body 2 formed by adhering the frictional force increasing material 16 into the outer can, the electrode body 2 is bonded to the outer can by heating to a temperature that does not deteriorate the battery performance.
[0009]
The manufacturing method of this invention can adhere | attach the electrode body 2 on an armored can using the frictional force increasing material 16 which increases a frictional force when it heats to 70-110 degreeC.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the following examples illustrate secondary batteries for embodying the technical idea of the present invention, and the present invention does not specify secondary batteries as the following.
[0011]
Further, in this specification, in order to facilitate understanding of the scope of claims, the numbers corresponding to the members shown in the examples are referred to as “the scope of claims” and “the means for solving the problems”. It is added to the member shown by. However, the members shown in the claims are not limited to the members in the embodiments.
[0012]
The secondary battery is a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery. However, the secondary battery can be any battery that can be charged, such as a nickel-hydrogen battery or a nickel-cadmium battery. The secondary battery may have a structure in which a metal sealing plate is airtightly fixed to a metal outer can, or the outer can and the sealing plate may be a plastic case. The secondary battery of the plastic case can be formed into a structure that can be used as a battery pack by molding the plastic case into an outer shape that can be mounted on the mounting portion of the electrical device.
[0013]
Hereinafter, a specific example in which the secondary battery is a lithium ion secondary battery will be described in detail. In particular, a battery having a full charge voltage of 3.5 to 5 V will be described in detail. In the secondary battery shown in FIGS. 1 to 3, an electrode body 2 is housed in a plastic case 1 that is an outer can and hermetically sealed with a sealing plate 3.
[0014]
The non-aqueous electrolyte secondary battery stores an electrode body 2 composed of a positive electrode, a negative electrode, and a separator, and a non-aqueous electrolyte, and a full charge voltage is set to 3.5 V or more and 5.0 V or less. When two or more electrode bodies are connected in series in one battery pack, the voltage output from the battery pack is the sum of the voltages of the respective electrode bodies. The full charge voltage here is the electrode body. The voltage per unit is shown. The electrode body 2 is formed by insulating a positive electrode and a negative electrode with a separator. The positive electrode and the negative electrode are stacked on each other with a separator interposed therebetween, and are wound in a spiral shape to form a multilayer stacked structure. The wound electrode body 2 is processed to a predetermined thickness by applying pressure from both sides. However, the electrode body 2 can also be manufactured by laminating a plurality of positive electrodes and negative electrodes cut into a predetermined shape via a separator.
[0015]
The positive electrode is manufactured as follows. Lithium cobaltate as an active material, graphite as a conductive agent, and polyvinylidene fluoride as a binder, respectively, at a solid content mass ratio of 90: 6: 4, N-methyl-2-pyrrolidone (NMP) The mixture is kneaded in a positive electrode mixture slurry. Next, after applying a specified amount of this positive electrode mixture slurry to an aluminum foil (thickness 15 μm) as a core, it is heated to evaporate NMP, adjusted to a specified thickness with a pressure roller, and then cut to a predetermined size The positive electrode is manufactured.
[0016]
The negative electrode is manufactured as follows. Graphite powder and a dispersion in which a rubber-based binder as a binder is dispersed in water are mixed at a solid content mass ratio of 95: 5 to obtain a negative electrode mixture slurry. Next, after applying a specified amount of this negative electrode mixture slurry to a copper foil (thickness 12 μm), it is heated to evaporate water, adjusted to a specified thickness with a pressure roller, and then cut into a predetermined size to form a negative electrode. To manufacture.
[0017]
The positive electrode and the negative electrode manufactured as described above are wound with a polyethylene microporous thin film separator sandwiched therebetween to produce a spiral electrode body, which is pressed from both sides to have a predetermined thickness. Let's say body 2. In order to connect the electrode body 2 to the inner surface of the outer can, the frictional force increasing material 16 is attached to the surface. The frictional force increasing material 16 melts when heated to a temperature that does not deteriorate the battery performance, for example, 70 to 110 ° C., preferably 80 to 100 ° C., and more preferably 80 to 90 ° C. It adheres to the can. As the frictional force increasing material 16, for example, a film in which a polyolefin film such as polypropylene or polyethylene is coated on one surface of a base film such as polypropylene or polyphenylene sulfide can be used. When such a material is heated, the state of the polyolefin layer changes and the surface frictional force increases. Furthermore, the frictional force increasing material 16 is provided with an adhesive layer on the other side in order to adhere to the surface of the electrode body 2 before heating. The frictional force increasing material 16 can be easily bonded to the surface of the electrode body 2 via the adhesive layer.
[0018]
The electrode body 2 in FIG. 1 is bonded so as to wind the frictional force increasing material 16 along the lower edge. With this structure, the side surface portion of the electrode body 2 can be firmly adhered to the inner surface of the outer can with the frictional force increasing material 16. Although not shown, the frictional force increasing material can be attached to almost the entire surface of the electrode body. In this secondary battery, the electrode body can be bonded to the inner surface of the outer can in an extremely large area, and the electrode body can be most strongly fixed to the outer can. However, the present invention does not specify the portion or area where the frictional force increasing material adheres the electrode body to the outer can. The frictional force increasing material can adhere a part of the surface of the electrode body to the inner surface of the outer can, or can adhere the entire surface or almost the entire surface of the electrode body to the inner surface of the outer can.
[0019]
Further, the electrode body 2 which is a spiral electrode body 2 formed by winding a positive electrode and a negative electrode with a separator interposed therebetween is bonded with a frictional force increasing material 16 at a terminal edge, and the frictional force increasing material 16 is used to form the spiral electrode body 2. Can be fixed to the wound state and adhered to the inner surface of the outer can. That is, a tape for fixing the terminal end of the spiral electrode body 2 can be used in combination with a tape for bonding the electrode body 2 to the outer can. This structure has an advantage that it can be adhered to the outer can while firmly holding the terminal end of the electrode body 2.
[0020]
A plastic case 1 that is an outer can into which the electrode body 2 is placed is composed of a main body 1A and a bottom lid 1B. However, the plastic case 1 as an outer can can be integrally formed as a whole consisting of the main body and the bottom lid. The plastic case 1 has an inner surface and a surface made of plastic, or the whole made of plastic. The bottom lid 1B is formed of a plastic material that has better impact resistance than the main body 1A. The plastic of the bottom lid 1B having excellent impact resistance can be reinforced by embedding reinforcing fibers. As the reinforcing fibers, inorganic fibers such as glass fibers and carbon fibers, or synthetic fibers such as polyester fibers are used. Further, the bottom lid 1B can be reinforced by inserting a reinforcing metal plate therein. As the reinforcing metal, aluminum, an aluminum alloy, stainless steel, or the like is formed by pressing a metal plate into a predetermined shape, and inserting the metal plate into a plastic for molding the bottom lid 1B. The bottom lid 1B having this structure also has a feature that it is possible to prevent the permeation of moisture by a buried reinforcing metal.
[0021]
Furthermore, the bottom lid 1B and the main body 1A can be molded from different plastics, and the impact resistance of the bottom lid 1B can be made stronger than that of the main body 1A. In this plastic case 1, the bottom lid 1B is formed of a plastic having a shock-absorbing effect such as ABS resin or fluororesin, and the body portion 1A is made of heat such as polyethylene, polypropylene, nylon, EVA, polyester or the like. Molded with plastic plastic. Further, the plastic case 1 may be made of a plastic material having a higher impact resistance than that of the main body 1A by molding the bottom lid 1B with a plastic composite material in which a plurality of plastic layers made of different materials are laminated. it can. The bottom lid 1B is formed, for example, of an outer surface portion made of ABS resin, fluororesin, or a rubber-like elastic material such as synthetic rubber, which has excellent buffering action, and an inner portion is made of synthetic resin with little moisture permeation. To do. This bottom lid 1B is excellent in impact resistance and can reduce moisture permeation.
[0022]
The bottom lid 1B is fixed to the main body 1A by being welded or bonded to the bottom of the can of the main body 1A and hermetically fixed, or inserted when the main body 1A is molded. The bottom lid 1B and the main body 1A can be easily and reliably welded by ultrasonic welding. The bottom lid 1B that is inserted and fixed to the main body 1A is formed by molding at least a contact surface with the main body 1A with a thermoplastic plastic or applying a hot melt adhesive to the surface of the contact surface. When the bottom lid 1B is insert-molded into the main body portion 1A, the thermoplastic or hot melt adhesive of the bottom lid 1B is melted by the plastic in a molten state for molding the main body portion 1A, and there is a gap in the plastic of the main body portion 1A. Are connected together.
[0023]
As shown in FIG. 3, the plastic case 1 is formed into a three-dimensional shape whose outer shape is detachably set on the mounting portion 21 of the electric device 20, and the inner shape is a shape into which the electrode body 2 and the nonaqueous electrolyte are placed. It is molded into. The plastic case 1 is an integrated structure of an outer can of a non-aqueous electrolyte secondary battery containing an electrode body 2 and a non-aqueous electrolyte and an outer case for specifying the outer shape of the secondary battery. Used in both battery case and secondary battery case. As shown in FIG. 4, the plastic case 1 into which the spiral electrode body 2 having a predetermined thickness by pressurization is formed is formed into an elongated cylindrical shape having both ends semicircular. Although not shown, a plastic case for storing an electrode body formed by laminating a large number of electrodes is processed into a cylindrical shape having an inner cross-sectional shape of a rectangle. Further, the outer shape of the plastic case 1 is formed into a shape that can be detachably attached to the electric device 20.
[0024]
Further, the plastic case 1 shown in FIGS. 4 and 5 has a blocking layer 1c for preventing moisture and gas permeation therein to reduce moisture and gas permeability. The blocking layer 1c is provided so as to be laminated on the whole plastic case 1, that is, on the whole of the main body 1A and the bottom lid 1B, or is laminated on the whole of the main body 1A. The blocking layer 1c is a metal layer such as aluminum or an aluminum alloy, or an inorganic layer such as silica or alumina. The plastic case 1 having the blocking layer 1c as a metal layer is manufactured by insert-molding a metal thin film, or is manufactured by insert-molding a metal molded body formed by pressing a metal.
[0025]
The plastic case 1 having the blocking layer 1c as a metal layer or an inorganic layer is manufactured by molding the inner case portion 1a located on the inner side and the outer case portion 1b located on the outer side as follows. The inner case portion 1a is molded with plastic. The main body portion of the inner case portion 1a is formed into a cylindrical shape having an inner shape that is optimal for inserting the electrode body 2. The inner case part 1a is formed into a shape that closes the bottom of the can with a bottom lid, or is formed into a cylindrical shape with the can bottom open, and is closed with a separately formed bottom lid. The inner case portion 1a molded into a shape that closes the bottom with the bottom lid is formed by molding the bottom lid and the main body portion with different plastics, so that the separately molded bottom lid is insert-molded and fixed to the main body portion, or Molding is performed by injecting plastic for molding the bottom lid and plastic for molding the main body into the molding chamber of the mold. A metal or an inorganic material is vapor-deposited on the outer surface of the cylindrical inner case portion 1a, and the entire outer surface of the inner case portion 1a is covered with a blocking layer 1c. Thereafter, the inner case portion 1a is temporarily fixed in a molding chamber for molding the outer case portion 1b, molten plastic is injected into the molding chamber of the outer case portion 1b, and the inner case portion 1a is inserted into the outer case portion 1b. Mold.
[0026]
As described above, the plastic case 1 in which the blocking layer 1c is laminated can block the permeation of moisture and gas by the blocking layer 1c. For this reason, the plastic case 1 can be molded with plastic that allows moisture and gas to pass therethrough. Therefore, the plastic case 1 having this structure can be molded from most plastics such as polyethylene (PE), polypropylene (PP), nylon, ABS, EVA, vinyl chloride, polyester, and the like. On the other hand, it is preferable to use a plastic that does not dissolve or swell in the organic solvent used in the electrolytic solution for the inner case 1a that comes into contact with the electrolytic solution. Crystalline polymer (LCP), polyphenylene sulfide (PPS), polyethersulfone ( PES), polybutylene terephthalate (PBT), polyamideimide (PAI), polyphthalamide (PPA), polyether ether cane (PEEK) and the like can be used.
[0027]
As shown in FIG. 6, the plastic case 1 can also be formed of a plastic composite material in which different types of plastics are laminated. The plastic case 1 has an airtight plastic 1d that can prevent moisture and gas from passing therethrough. Fluorine resin, polyvinylidene chloride, ethylene vinyl alcohol copolymer, etc. can be used for the airtight plastic 1d. This plastic case 1 is manufactured as follows. The inner case portion 1a is molded, the inner case portion 1a is temporarily fixed in the molding chamber of the mold, and the airtight plastic 1d is molded on the outer surface of the inner case portion 1a, and the inner case portion is formed on the airtight plastic 1d. Insert 1a. Further, the inner case portion 1a is temporarily fixed in a molding chamber of a mold for forming the outer case portion 1b, and the inner case portion 1a is inserted when the outer case portion 1b is formed. The plastic case 1 in FIG. 6 has a three-layer structure in which an airtight plastic 1d is provided between the inner case 1a and the outer case 1b. The plastic case is formed by molding the inner case with an airtight plastic. Further, a two-layer structure formed by molding an outer case part on the outer side thereof can also be used. Since the plastic case with this structure is also an airtight plastic and prevents moisture and gas from passing therethrough, other plastics can be molded from most plastics in the same manner as the plastic case 1 in FIG.
[0028]
The plastic case 1 fixes the sealing plate 3 to the opening with the electrode body 2 inserted. Since the sealing plate 3 is welded to the plastic case 1 and is securely fixed, the plastic case 1 is formed of thermoplastic plastic. However, the plastic case 1 can be molded from thermosetting plastic and the sealing plate 3 can be adhered and fixed.
[0029]
The plastic case 1 formed of thermoplastic plastic can be easily fixed with the sealing plate 3 by ultrasonic welding. The sealing plate 3 welded to the plastic case 1 also has a welded surface with the sealing plate 3 formed of a thermoplastic plastic. The plastic case 1 and the sealing plate 3 shown in FIGS. 5 and 6 are provided with a ridge 6 on one side and a connecting groove 7 for guiding the ridge 6 on the other side for reliable welding. The plastic case 1 and the sealing plate 3 are firmly and airtightly welded by ultrasonic welding while the ridge 6 is put in the connecting groove 7.
[0030]
As shown in FIGS. 1 and 7, the sealing plate 3 is formed of plastic as a whole, and the electrode terminal 8 including the positive electrode terminal 8 </ b> A and the negative electrode terminal 8 </ b> B is inserted and fixed so as to be exposed on the surface. . The sealing plate 3 is fixed by inserting a current collecting plate 9 composed of a positive current collecting plate 9A and a negative current collecting plate (not shown) so as to be exposed in the plastic case 1 which is the lower surface thereof. The sealing plate 3 connects a current collecting base material 10 to electrode terminals 8 which are a positive electrode terminal 8A and a negative electrode terminal 8B. The current collecting base material 10 is embedded in the sealing plate 3 and electrically connects the positive electrode terminal 8A to the positive electrode current collecting plate 9A and the negative electrode terminal 8B to the negative electrode current collecting plate (not shown). Further, the current collecting base material 10 shown in the figure is partially cut into a fusing portion 11 so that the fusing portion is blown when an overcurrent flows. In the current collecting base material 10, when an overcurrent flows, the fusing part 11 is blown by the current and cuts off the current flowing through the secondary battery. Further, the sealing plate 3 shown in the figure is provided with an injection hole 12 for injecting a non-aqueous electrolyte, and the injection hole 12 is airtightly closed with a sealing plug 13. In this secondary battery, an electrode body 2 is placed in a plastic case 1 to fix a sealing plate 3, a nonaqueous electrolyte is injected from an injection hole 12 of the sealing plate 3, and then the injection hole 12 is closed with a sealing plug 13. To do. In the secondary battery, before the sealing plate 3 is fixed to the plastic case 1, after the electrode body 2 is inserted, a nonaqueous electrolytic solution is inserted, and the opening of the plastic case 1 is hermetically closed with the sealing plate 3. You can also. In this secondary battery, it is not necessary to provide the non-aqueous electrolyte injection hole 12 in the sealing plate 3. Further, the sealing plate 3 shown in the figure is partially formed thinly and provided with a safety valve 14. The safety valve 14 is opened when the pressure in the plastic case 1 becomes higher than the set pressure, and prevents pressure destruction of the plastic case 1.
[0031]
In addition, although the example using a plastic outer can was demonstrated above, this invention can also be made into metal cans, such as aluminum or aluminum alloy.
[0032]
【The invention's effect】
Manufacturing method of the secondary batteries of the present invention has a feature that can effectively prevent the positional deviation of the electrode body due to the impact. It secondary batteries production method of the present invention, between the surface and the outer can inside surface of the electrode body was disposed friction increasing material to be melted when heated to a temperature not to lower the cell performance This is because the friction force increasing material is heated and melted to bond the electrode body and the outer can. In particular, the present invention inserts an electrode body to which a frictional force increasing material is attached into an outer can and melts the frictional force increasing material to bond the electrode body to the inner surface of the outer can. As a structure that can be mass-produced, there is a feature that can effectively prevent displacement of the electrode body. Moreover, since the frictional force increasing material is melted when heated to a temperature not deteriorating the battery performance, the electrode body can be reliably bonded to the inner surface of the outer can without adversely affecting the battery.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional perspective view of a secondary battery according to an embodiment of the present invention. FIG. 2 is a front view of the secondary battery shown in FIG. 1. FIG. FIG. 4 is an enlarged horizontal sectional view of the plastic case of the secondary battery shown in FIG. 1. FIG. 5 is an enlarged vertical sectional view of the plastic case of the secondary battery shown in FIG. FIG. 7 is an enlarged vertical sectional view showing another example of the plastic case. FIG. 7 is an enlarged sectional perspective view of the secondary battery shown in FIG.
DESCRIPTION OF SYMBOLS 1 ... Plastic case 1A ... Main-body part 1B ... Bottom cover
1a ... inner case 1b ... outer case
1c: barrier layer
DESCRIPTION OF SYMBOLS 1d ... Airtight plastic 2 ... Electrode body 3 ... Sealing plate 6 ... Convex strip 7 ... Connection groove 8 ... Electrode terminal 8A ... Positive electrode terminal 8B ... Negative electrode terminal 9 ... Current collector plate 9A ... Positive electrode current collector plate 9B ... Negative electrode current collector plate DESCRIPTION OF SYMBOLS 10 ... Current collection base material 11 ... Fusing part 12 ... Injection hole 13 ... Sealing plug 14 ... Safety valve 16 ... Friction power increasing material 20 ... Electric equipment 21 ... Mounting part

Claims (2)

After the electrode body (2) and the electrolytic solution are put into the outer can, the secondary battery manufacturing method for hermetically sealing the opening of the outer can,
Before being put in the outer can, the surface of the electrode body (2) is attached with a frictional force increasing material (16) that increases the adhesion when heated to a temperature that does not degrade the battery performance. A method for producing a secondary battery, comprising: putting an electrode body (2) attached to an outer can, and then heating the electrode body (2) to the outer can by heating to a temperature that does not deteriorate battery performance. The method for manufacturing a secondary battery according to claim 1 , wherein the electrode body (2) is bonded to the outer can using a frictional force increasing material (16) that increases in frictional force when heated to 70 to 110 ° C.

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