JP2016225237A - Secondary battery manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery manufacturing method capable of securely suppressing the deterioration of battery performance.SOLUTION: The secondary battery manufacturing method includes: a step for housing an electrode laminate, having a positive electrode and a negative electrode laminated in a manner to sandwich a separator, and an electrolyte into an outer package, and for sealing the peripheral edge part of the outer package to configure a secondary battery; a first charging step for charging the secondary battery; after the first charging step, a first gas movement step for moving gas in the electrode laminate to outside the electrode laminate; after the first gas movement step, a second charging step for charging the secondary battery; and after the second charging step, a second gas movement step for moving gas in the electrode laminate to outside the electrode laminate.SELECTED DRAWING: Figure 1

Description

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

  2. Description of the Related Art It is known that secondary battery such as a lithium ion battery deteriorates battery characteristics such as battery voltage and battery capacity while repeatedly charging and discharging. If the speed at which the battery characteristics are reduced is high, the battery life is shortened. Therefore, it is desired to suppress the speed at which the battery characteristics are reduced.

  Patent Document 1 discloses a method for manufacturing a secondary battery in which a film is formed on the surface of an electrode using an electrolytic solution containing an additive in order to suppress the speed at which the battery characteristics deteriorate. This manufacturing method includes an electrolyte solution containing an additive and a sealing step in which a laminate in which a positive electrode and a negative electrode are laminated via a separator is contained and sealed, and a voltage higher than a voltage at which the additive decomposes And a first charging step of charging the secondary battery. Thereby, an additive decomposes | disassembles and a film is formed on the surface of an electrode. Gas is generated when the additive decomposes. If this gas is present in the electrode stack, the function between the electrode and the electrolyte is hindered, so that the battery performance is degraded. For this reason, in this manufacturing method, the degassing step of removing the gas by opening the outer package after the first charging step, the re-sealing step of resealing the outer package, and charging the secondary battery to full charge A second charging step. Thereby, since the gas generated in the first charging step is removed in the subsequent degassing step, it is possible to suppress a decrease in battery performance.

JP 2013-48113 A

However, in the second charging step, the additive may be decomposed to generate gas. In the method described in Patent Document 1, when gas is generated in the second charging step, this gas remains inside the electrode laminate, causing a decrease in battery performance.
This invention is made | formed in view of said situation, and it aims at providing the manufacturing method of the secondary battery which can suppress the fall of battery performance more reliably.

A method for manufacturing a secondary battery according to the present invention includes:
A step of accommodating a battery laminate and an electrolyte in which a positive electrode and a negative electrode are laminated via a separator, and constituting a secondary battery;
A first charging step of charging the secondary battery;
After the first charging step, a first gas moving step of moving the gas in the electrode stack outside the electrode stack;
A second charging step of charging the secondary battery after the first gas transfer step;
After the second charging step, a second gas moving step of moving the gas in the electrode stack to the outside of the electrode stack.

  According to the present invention, it is possible to more reliably suppress a decrease in battery performance.

It is a top view which shows typically the basic structure of the secondary battery manufactured with the manufacturing method of the secondary battery concerning the 1st Embodiment of this invention. It is a figure which shows typically the AA cross section of the secondary battery 100 of FIG. 3 is a flowchart for explaining a method of manufacturing the secondary battery of FIGS. 1 and 2. It is a figure for demonstrating heat sealing | fusion. 2 is a diagram showing a sealed portion of the secondary battery 100. FIG. It is a figure for demonstrating a degassing process. It is a figure which shows an example of the sealing position in a 3rd sealing process. It is explanatory drawing about a reseal process. It is explanatory drawing of the process of pressing an electrode laminated body. It is explanatory drawing of the process of pressing an electrode laminated body. It is a top view which shows typically the basic structure of the secondary battery manufactured with the manufacturing method of the secondary battery concerning the 2nd Embodiment of this invention. It is a figure which shows typically the BB cross-section structure of the secondary battery 200 of FIG. 4 is a flowchart for explaining a method of manufacturing a secondary battery 200 according to a second embodiment of the present invention. 6 is a flowchart for explaining a modification of the method for manufacturing secondary battery 200.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and drawing, the description which overlaps may be abbreviate | omitted by attaching | subjecting the same code | symbol about the component which has the same function.

(First embodiment)
[Basic structure of secondary battery]
1 and 2 are diagrams for explaining a basic structure of a secondary battery 100 manufactured by the method for manufacturing a secondary battery according to the first embodiment of the present invention. FIG. 1 schematically shows a planar configuration of the secondary battery 100. FIG. 2 schematically shows a cross-sectional configuration of the secondary battery 100 of FIG.

  The secondary battery 100 can be repeatedly charged and discharged, and is, for example, a lithium ion secondary battery. Referring to FIGS. 1 and 2, the secondary battery 100 has an electrode stack 5 in which a plurality of positive electrodes 2 and negative electrodes 3 are alternately stacked via separators 4. The electrode laminate 5 is accommodated in the exterior body 7 together with the electrolytic solution 6.

  One end of a positive electrode terminal 8 is connected to the positive electrode 2 of the electrode laminate 5, and one end of a negative electrode terminal 9 is connected to the negative electrode 3. Further, the other end side of the positive electrode terminal 8 and the other end side of the negative electrode terminal 9 are drawn out to the outside of the exterior body 7 and exposed. In FIG. 2, a part of each layer constituting the electrode laminate 5 (a layer located at an intermediate portion in the thickness direction) is not shown. In FIG. 1, a pair of terminals (positive electrode terminal 8 and negative electrode terminal 9) are arranged side by side on the same one edge, but positive electrode terminal 8 is arranged on one edge and negative electrode on the other edge. Terminal 9 may be arranged.

  The positive electrode 2 includes a positive electrode current collector 10 and a positive electrode active material layer 11 formed on a part of the front and back surfaces of the positive electrode current collector 10. Similarly, the negative electrode 3 includes a negative electrode active material layer 13 formed on part of the front and back surfaces of the negative electrode current collector 12. The separator 4 is larger than the positive electrode active material layer 11 and the negative electrode active material layer 13 and electrically insulates between the positive electrode 2 and the negative electrode 3.

  The portion where the positive electrode active material layer 11 is not provided on the positive electrode current collector 10 and the portion where the negative electrode active material layer 13 is not provided on the negative electrode current collector 12 are electrode terminals (positive electrode terminal 8 or negative electrode terminal 9). Used as a tab to connect to. The positive electrode tabs are gathered on the positive electrode terminal 8 and connected to each other by a method such as ultrasonic welding together with the positive electrode terminal 8. Similarly, the negative electrode tabs are gathered on the negative electrode terminal 9 and connected together with the negative electrode terminal 9 by a method such as ultrasonic welding.

  In the secondary battery 100, the exterior body 7 is made of a laminate film having flexibility, for example. The exterior body 7 may be formed by bending one laminate film and heat-sealing the three surrounding sides, or by superposing two laminate films and heat-sealing the four surrounding sides. Although not shown, the laminate film forming the exterior body 6 has a heat fusion layer (inner layer), a metal layer, and a protective layer (outer layer) laminated in this order.

  The positive electrode active material layer 11 is formed by applying a positive electrode slurry obtained by kneading a positive electrode active material, a binder, and an organic solvent to the surface of the positive electrode current collector 10 and drying it. . As the positive electrode active material, for example, lithium metal oxides such as lithium manganate (LiMnO2), lithium cobaltate (LiCoO2), lithium nickelate (LiNiO2), and lithium iron phosphate (LiFePO4) can be used. Examples of the binder include poly (vinylidene fluoride) (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polytetrafluoroethylene, polypropylene, Polyethylene, polyimide, polyamideimide and the like can be used. As the organic solvent, for example, N-methyl-2-pyrrolidone can be used. Further, the positive electrode current collector 10 is made of an electrochemically stable metal foil such as an aluminum foil or an aluminum alloy foil.

  The negative electrode active material layer 13 is formed by applying a negative electrode slurry formed by mixing a negative electrode active material, a binder, and an organic solvent to the surface of the negative electrode current collector 12 and drying and rolling. As the negative electrode active material, a material having a property of occluding and releasing lithium ions of the positive electrode active material can be used. For example, carbon materials such as graphite and amorphous carbon, lithium metal materials, and alloy systems such as silicon and tin Materials, oxide-based materials such as Nb2O5 and TiO2, or composites thereof can be used. The negative electrode current collector 12 is made of an electrochemically stable metal foil such as copper foil, nickel foil, stainless steel foil, or iron foil.

  The separator 4 has a role of preventing an electrical short circuit between the positive electrode 2 and the negative electrode 3 and holding an electrolytic solution. The separator 4 is mainly made of a resin porous film, a woven fabric, a non-woven fabric, or the like. As the resin component, for example, a polyolefin resin such as polypropylene or polyethylene, a polyester resin, an acrylic resin, a styrene resin, or a nylon resin can be used. The separator 4 is not limited to a single layer film, and may have a layer structure in which a plurality of layers are stacked. The separator 4 having a layer structure may be, for example, a three-layer structure in which a polypropylene film is sandwiched between polyethylene films, or a laminate of a polyolefin microporous film and an organic nonwoven fabric.

The electrolytic solution 6 is an example of an electrolyte used in the secondary battery 100, and may be a nonaqueous electrolytic solution in which a lithium salt is dissolved in an organic solvent. The electrolytic solution 6 includes an additive for forming a film on the negative electrode 3. The additive may be an organic compound that decomposes at a lower voltage than the organic solvent and forms a film on the negative electrode. As the organic solvent of the electrolytic solution 6, for example, an aprotic organic solvent can be used. Aprotic organic solvents include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dimethyl sulfoxide, sulfolane, γ-butyrolactone, 1,2-dimethoxyethane, N, N-dimethylformamide, tetrahydrofuran, 1, 3-dioxolane, 2-methyltetrahydrofuran, diethyl ether and the like. In addition, the aprotic organic solvent can be used by selecting one or more of them from the above-mentioned examples. Examples of the lithium salt of the electrolytic solution 6 include lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium hexafluoroarsenate (LiAsF ₆ ), and the like. Of these, one or more can be selected and used.

[Method for producing secondary battery]
FIG. 3 is a flowchart for explaining a method of manufacturing the secondary battery 100 according to the first embodiment of the present invention.

  In this manufacturing method, first, a first sealing step is performed in which the electrode laminate 5 is accommodated in the exterior body 7 and the three sides are sealed (step S100). FIG. 4 is a diagram for explaining thermal fusion, and FIG. 5 is a diagram showing a sealed portion of the secondary battery 100. As shown in FIG. 4, in the first sealing step, the sealed portion of the outer package 7 in a state where the electrode laminate 5 is accommodated is sandwiched from above and below by the two heaters H1 and H2 and heat is applied. Thereby, it heat-seals in the peripheral part of the exterior body 7. FIG. Specifically, in the peripheral portion of the outer package 7, the positive electrode terminal 8 or the negative electrode terminal 9 and the outer package are provided at the portions where the positive terminals 8 or the negative electrodes 9 are sandwiched between the outer packages 7 or between the outer packages 7. 7 is heat-sealed through a heat-adhesive resin. In the first sealing step of step S100, the heater H1 is sequentially moved to the positions indicated as heaters H1-1, H1-2, and H1-3 in FIG. 5, and H2 is moved to a position corresponding to the position of H1. Then, heat sealing is performed to seal three sides of the peripheral portion of the exterior body 7. In this embodiment, since the exterior body 7 is composed of two laminated films, the sealing portion has three sides. However, when one laminated film is folded and used, the sealing portion is a heater. It becomes the part of 2 sides shown by H1-1 and H1-3.

  Returning to the description of FIG. Part of the peripheral edge portion of the exterior body 7 is sealed by the first sealing process in step S100, and one side of the exterior body 7 is in an open state as an unsealed portion. The electrolytic solution 6 is injected from one side of the unsealed (Step S101).

  After the electrolytic solution 6 is injected, a second sealing step for sealing one side of the exterior body 7 that is not sealed is performed (step S102). In the second sealing step, the heaters H1 and H2 are arranged at the position of the heater H1-4 shown in FIG. 5 with the exterior body 7 interposed therebetween, and heat is applied to the exterior body 7. At this time, since the electrolytic solution 6 is accommodated in the outer package 7, the secondary sealing process is performed on the secondary battery 100 with the unsealed portion facing up. The secondary battery 100 is configured by the first sealing step (step S100), the step of injecting the electrolytic solution (step S101), and the second sealing step (step S102) described above. Hereinafter, the first sealing step, the step of injecting the electrolytic solution, and the second sealing step are collectively referred to as a step of configuring the secondary battery.

  When the secondary battery 100 is configured, the configured secondary battery 100 is charged via the positive electrode terminal 8 and the negative electrode terminal 9. This charging is also referred to as first charging, and is performed up to a first voltage equal to or higher than a voltage at which the additive contained in the electrolytic solution 6 is decomposed. In the first charging, when the additive is decomposed, a film is formed on the surface of the negative electrode 3, and at the same time, gas is generated (step S103).

  If the gas generated in the charging process remains in the electrode laminate 10, the reaction between the electrode and the electrolytic solution 6 may be inhibited, and in this case, the battery performance is deteriorated. For this reason, the gas movement process which moves the gas in the electrode laminated body 5 out of the electrode laminated body 5 is performed after 1st charge. The gas movement process performed after the first charging process is hereinafter referred to as a first gas movement process. When the amount of gas generated in the first charging process is large and it is not appropriate to leave the gas inside the exterior body 7, the first gas moving process is a gas venting process that moves the gas to the outside of the exterior body 7. .

  FIG. 6 is a diagram for explaining the degassing step. Specifically, in the degassing step, a part of the outer package 7 is opened, and the secondary battery 100 is placed under reduced pressure. For example, as shown in FIG. 6, the secondary battery 100 is set up by the stand 50 and the support 51. Then, a part of the exterior body 7 is unsealed by opening a hole 19 at a position where it does not interfere with the electrode laminate 5 with an opening means for opening the exterior body 7, for example, a needle. Thereafter, the secondary battery 100 is put into the vacuum chamber 52 to reduce the pressure, and the gas in the exterior body 7 is discharged to the outside of the exterior body 7. As a result, the gas present in the electrode laminate 5 moves to the outside of the exterior body 7.

Returning to the description of FIG. The exterior body 7 opened in the degassing process is then resealed (step S105). Hereinafter, this reseal step is referred to as a third seal step. FIG. 7 is a diagram illustrating an example of a sealing position in the third sealing step. If the position at which the outer package 7 is sealed in the second sealing step is the temporary sealing line L1, the hole 19 is opened inside the temporary sealing line L1 in the degassing step in step S104. In this case, in the resealing step after the degassing step, the outer package 7 is sealed by the sealing line L2 inside the hole 19. Thus, when including the degassing process which unseal | opens the exterior body 7 and discharges gas out of the exterior body 7, it is necessary to prepare the exterior body 7 larger than the final sealing line L2. For this reason, the larger the number of times the sealing and unsealing of the exterior body 7 is repeated, the larger the area of the extra exterior body 7 that is necessary in the manufacturing process but is not included in the final product.
FIG. 8 is an explanatory diagram of the reseal step. With the base 50 and the support 51, the secondary battery 100 is in a standing state, and the exterior body 7 is resealed with the sealing portion sandwiched between the heaters H 1 and H 2. At this time, by arranging the heaters H <b> 1 and H <b> 2 inside the hole 19, the exterior body 7 can be resealed inside the hole 19.

  Returning to the description of FIG. The secondary battery 100 is charged after the reseal step in step S105. This charging is also referred to as second charging, and is performed up to a second voltage higher than the first voltage. For example, the second voltage may be a voltage corresponding to a fully charged state (step S106).

  After the second charging step, a gas moving step for moving the gas in the electrode stack 5 to the outside of the electrode stack 5 is performed. The gas movement process performed after the second charging process is also referred to as a second gas movement process, and in the present embodiment, the second gas movement process is performed by pressing the electrode laminate 5 from above the exterior body 7. In this step, the gas in the electrode stack 5 is moved outside the electrode stack 5 and into the exterior body 7 (step S107). 9 and 10 are explanatory diagrams of a process of pressing the electrode laminate 5. In this step, as shown in FIG. 9, the secondary battery 100 is moved by pressing the secondary battery 100 while rotating the rollers R1 and R2 so as to sandwich the multilayer electrode body 5, thereby moving the secondary battery 100. Press. At this time, the rollers R1 and R2 start pressing from the side where the positive electrode terminal 8 and the negative electrode terminal 9 of the secondary battery 100 are provided, and move the secondary battery 100 in the direction of the arrow in FIG. The electrode laminate 5 is pressed from end to end in the longitudinal direction.

  As described above, according to the first embodiment of the present invention, the gas in the electrode stack 5 is moved out of the electrode stack 5 after the second charging step. The generated gas can be moved out of the electrode stack 5. Therefore, it is possible to further suppress the deterioration of the battery performance.

  In the present embodiment, the secondary battery 100 has the positive electrode terminal 8 and the negative electrode terminal 9 arranged on the same side, but the present invention is not limited to such an example. The manufacturing method of the present embodiment can be similarly used for a secondary battery in which the positive electrode terminal 8 and the negative electrode terminal 9 are arranged in opposite directions. Moreover, in this embodiment, although the 1st gas movement process was made into the degassing process, this invention is not limited to this example. The first gas movement step may be a pressing step as in the second gas movement step.

(Second Embodiment)
[Basic structure of secondary battery]
FIG. 11 and FIG. 12 are diagrams for explaining a basic structure of a secondary battery 200 manufactured by the method for manufacturing a secondary battery according to the second embodiment of the present invention. FIG. 11 schematically shows a planar configuration of the secondary battery 200. FIG. 12 schematically shows a cross-sectional configuration of the secondary battery 200 of FIG. 11 taken along the line BB.

  Since each component constituting the secondary battery 200 is the same as that of the secondary battery 100 described in the first embodiment, the description thereof is omitted here. Since the configuration of the separator 4 is different from that of the secondary battery 100 in the secondary battery 200, differences from the secondary battery 100 will be mainly described here.

The secondary battery 200 has a positive electrode terminal 8 and a negative electrode terminal 9 arranged in the same direction. Each of the positive electrode terminal 8 and the negative electrode terminal 9 is sandwiched between two exterior bodies 7 and bonded to each exterior body 7. Since the positive electrode terminal 8 is connected to the positive electrode 2 and the negative electrode terminal 9 is connected to the negative electrode 3, the electrode laminate 5 is fixed to the exterior body 7 at the side where the positive electrode terminal 8 and the negative electrode terminal 9 are arranged. It will be in the state. However, since the electrode laminate 5 is not fixed to the exterior body 7 except the side where the positive electrode terminal 8 and the negative electrode terminal 9 of the secondary battery 100 are disposed, the electrode laminate 5 moves in the space inside the exterior body 7. End up. Therefore, in the secondary battery 200, the separator 4 is further connected to the positive electrode active material layer 11 and the negative electrode active material layer 13 in the side where the positive electrode terminal 8 and the negative electrode terminal 9 are not disposed, as compared with the separator 4 of the first embodiment. The protruding portion of the separator 4 is sandwiched and joined between the exterior bodies 7.
The separator 4 is joined to the exterior body 7 by a method such as ultrasonic welding. The secondary battery 200 includes a joint portion 21 between the separator 4 and the outer casing 7 along the side opposite to the side where the positive electrode terminal 8 and the negative electrode terminal 9 are arranged, among the four sides of the rectangular outer casing 7. There are three. The joint portion 21 is a region different from the sealed portion to which the exterior body 7 is fused, and a region that is not sealed or joined exists between the joint portion 21 and the sealed portion. The bonding portion 21 has a bonding strength lower than that of the portion heat sealed at the peripheral edge of the outer package 7.

  Further, the volume of the electrolytic solution 6 injected into the secondary battery 200 is larger than the total pore volume in the electrode laminate 5. When the pore volume in the electrode laminate 5 is fully filled with the electrolytic solution 6, the liquid volume coefficient of the secondary battery 200 is more than 1.0. About 1.1 to 1.6 is preferable. As the liquid quantity coefficient increases, the secondary battery 200 can be prevented from withering, and thus the life of the secondary battery 200 can be extended.

[Method for producing secondary battery]
FIG. 13 is a flowchart for explaining a method of manufacturing the secondary battery 200 according to the second embodiment of the present invention. In FIG. 13 and the following description, processes similar to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof is omitted. In the description of FIG. 3, the secondary battery 100 is replaced with the secondary battery 200.

  In this manufacturing method, first, a first sealing step is performed in which the electrode laminate 5 is accommodated in the exterior body 7 and three sides are sealed. At this time, as described with reference to FIGS. 4 and 5, the three sides of the outer package 7 are sealed together with the positive electrode terminal 8 and the negative electrode terminal 9. The first sealing step includes a joining step of joining the separator 4 to the exterior body 7 along the side opposite to the side where the positive electrode terminal 8 and the negative electrode terminal 9 are arranged. At this time, one side of the outer package 7 is unsealed and opened. (Step S200).

  And the electrolyte solution 6 is inject | poured from this unsealed part (step S101). After the electrolytic solution 6 is injected, a second sealing step for sealing the unsealed portion of the exterior body 7 is performed (step S102). The secondary battery 200 is configured by the first sealing step (step S200), the step of injecting the electrolytic solution (step S101), and the second sealing step (step S102) described above.

  When the secondary battery 200 is configured, before the secondary battery 200 is charged, a gas moving process is performed in which the outer package 7 is pressed to move the gas in the electrode stack 5 to the outside of the electrode stack 5. The gas movement process performed before charging the secondary battery 200 is hereinafter referred to as a gas movement process before charging. In the gas moving step before charging, the gas in the electrode stack 5 such as air is moved outside the electrode stack 5 and into the exterior body 7 (step S203). In addition, the specific method of pressing the electrode laminated body 5 in the gas movement process before charging is the same as step S107 in FIG.

  After the outer package 7 is pressed, the secondary battery 200 is charged through the positive terminal 8 and the negative terminal 9 (step S103).

  After the first charging step, a first gas moving step is performed in which the gas in the electrode laminate 5 is moved out of the electrode laminate 5. This 1st gas movement process is a process of pressing the electrode laminated body 5 from on the exterior body 7, and gas is moved outside the electrode laminated body 5 and inside the exterior body 7 (step S202). .

  A 2nd charge process is performed after a 1st gas movement process (step S106).

  In addition, after the second charging step, a gas moving step is performed in which the gas in the electrode stack 5 is moved out of the electrode stack 5. The gas movement process performed after the second charging process is also referred to as a second gas movement process, and in the present embodiment, the second gas movement process is performed by pressing the electrode laminate 5 from above the exterior body 7. In this step, the gas in the electrode stack 5 is moved outside the electrode stack 5 and into the exterior body 7 (step S203). The specific method for pressing the electrode laminate 5 is the same as in step S107 of FIG. 3, but here, the pressure for pressing the electrode laminate 5 is different from that in FIG.

  As described above, the secondary battery 200 has the joint portion 21 in which the separator is joined to the exterior body 7, and this joint portion 21 is joined more than the portion heat-sealed at the peripheral edge of the exterior body 7. The strength is weak. For this reason, it is necessary to perform the process of pressing the electrode laminated body 5 with such a pressure that the joining portion 21 is not peeled off. In addition, since gas is generated when the additive is decomposed in the first charging and the second charging, the second gas moving step is more likely to occur during the second gas moving step than during the gas moving step before charging. The empty space inside the outer package 7 of the secondary battery 200 is small. For this reason, it is preferable to make the pressure applied to the electrode laminated body 5 in a 2nd gas movement process smaller than the pressure applied to the electrode laminated body 5 in the gas movement process before charge. Note that the pressure applied to the electrode stack 5 in the first gas transfer step is smaller than the pressure applied to the electrode stack 5 in the gas transfer step before charging. In addition, the pressure applied to the electrode stack 5 in the first gas transfer step can be greater than the pressure applied to the electrode stack 5 in the second gas transfer step.

(Modification of the second embodiment)
FIG. 14 is a flowchart for explaining a modification of the method for manufacturing secondary battery 200. In FIG. 14 and the following description, processes similar to those in FIG. 3 or FIG. 13 are denoted by the same reference numerals, and detailed description thereof is omitted. In the description of FIG. 3, the secondary battery 100 is replaced with the secondary battery 200.

  First, the 1st sealing process in which the electrode laminated body 5 is accommodated in the exterior body 7, 3 sides are sealed, and the separator 4 is joined to the exterior body 7 is performed (step S200). Thereafter, the electrolytic solution 6 is injected into the exterior body 7 from one side that is not sealed (step S101). And the 2nd sealing process by which one side of unsealing is sealed is performed (Step S102).

  Then, the gas movement process before the charge which presses the electrode laminated body 5 from the exterior body 7 is performed (step S201). Thereafter, the secondary battery 200 is charged by the first charging (step S103).

  After the first charging, a degassing process is performed as the first gas movement process (step S104). Then, after the degassing step, re-sealing as the third sealing step is performed (step S105). Then, after the re-sealing, the second charging for charging the secondary battery 200 is performed (step S106). After the second charge, a second gas moving step of pressing the electrode laminate 5 from the top of the outer package 7 is performed (step S203).

  As described above, in the method for manufacturing the secondary battery 200 according to the modification of the second embodiment of the present invention, the degassing step is performed after the first charging, and therefore, the empty space is reduced due to the increase in the gas volume. Becomes smaller. However, when performing a degassing process, as shown in FIG. 7, the exterior body 7 is sealed by the sealing line L2 closer to the electrode laminated body 5 than the temporary sealing line L1. For this reason, the surplus volume in the exterior body 7 changes before the degassing step and after the resealing step. Here, the surplus volume is obtained by subtracting the volume of the electrode laminate 5 from the volume inside the outer package 7. The surplus volume is smaller after the reseal step than before the degas step. For this reason, when the exterior body 7 is pressed after the re-sealing process rather than before the degassing process, a force is more easily applied in a direction in which the joint portion 21 between the separator 4 and the exterior body 7 is peeled off. Therefore, also in this modification, in order to suppress peeling of the joint portion 21, the pressure applied to the electrode stack 5 in the second gas transfer step is higher than the pressure applied to the electrode stack 5 in the gas transfer step before charging. It is preferable to reduce the size.

(Example)
A secondary battery 200 was manufactured according to the method for manufacturing the secondary battery 200 according to the second embodiment of the present invention shown in FIG. At this time, the joining portion 21 of the separator 4 and the exterior body 7 is formed by ultrasonic welding, and the strength of the joining portion 21 is 20 to 40 with respect to the strength of the portion heat sealed at the peripheral edge portion of the exterior body 7. %. Further, the value obtained by subtracting the surplus volume of the secondary battery 200 in the second gas transfer process from the surplus volume of the secondary battery 200 in the gas transfer process before charging is set to 35000 mm ³ , and the liquid quantity coefficient is set to 1.3. . In addition, the secondary battery 200 was manufactured by pressing the outer package 7 in the gas transfer step and the second gas transfer step before charging at the pressure shown in Table 1 below.

  As a result of manufacturing the secondary battery 200 under the above-described conditions, in Example 1, peeling of the joint portion 21 did not occur while 32 secondary batteries 200 were manufactured. Also in Example 2, peeling of the joint portion 21 did not occur among the 32 secondary batteries 200 manufactured. In Example 3, among the 32 secondary batteries 200 manufactured, the joint portion 21 peeled off in the three secondary batteries 200. Therefore, the pressure applied to the exterior body 7 in the second gas movement process is preferably about half of the pressure applied to the exterior body 7 in the gas movement process before charging. Further, the pressure applied to the outer package 7 is not limited to about half, but can be made smaller. However, if the pressure applied to the outer package 7 is too low, the movement of the gas in the electrode laminate 5 becomes insufficient. Since there is a possibility of causing a decrease in battery performance, it is more preferably up to about a quarter.

  As described above, also in the method for manufacturing the secondary battery 200 according to the second embodiment of the present invention, the gas in the electrode stack 5 is an electrode after the second charging step, as in the first embodiment. Since it is moved out of the stacked body 5, the gas generated in the second charging step can also be moved out of the electrode stacked body 5. Therefore, it is possible to more reliably suppress a decrease in battery performance.

  Moreover, the manufacturing method of the secondary battery which concerns on this embodiment is after the sealing process, and before the 1st charge process, before the charge which moves the gas in the electrode laminated body 5 out of the electrode laminated body 5 It further includes a gas transfer step. Thereby, before the 1st charge process, the gas in electrode layered product 5, for example, air etc., is moved out of electrode layered product 5, and the 1st charge process is performed in the state where there is little gas in electrode layered product 5. Is called. Therefore, the gas generated in the first charging step is more reliably moved out of the electrode laminate 5 in the first gas moving step, and the deterioration of the battery performance can be more reliably suppressed.

  In the secondary battery 200 according to this embodiment, the separator 4 projects in one direction from the positive electrode 2 and the negative electrode 3. In the method for manufacturing the secondary battery 200, the step of forming the secondary battery includes the step of joining the protruding portion of the separator 4 to the exterior body 7. Further, in the method for manufacturing the secondary battery 200, the second gas moving step and the gas moving step before charging are performed by pressing the electrode laminate 5 from above the exterior body 7 so that the gas in the electrode laminate 5 is electrode laminated. This is a step of moving to a space inside the exterior body 7 outside the body 5. And the pressure applied to the exterior body 7 in a 2nd gas movement process is smaller than the pressure applied to the exterior body 7 in the gas movement process before charge. For this reason, in a 2nd gas movement process, the fall of battery performance can be suppressed, suppressing that the part which the separator joined to the exterior body 7 peels.

  Moreover, in the modification which concerns on this embodiment, a 1st gas movement process is a process of opening the exterior body 7 and moving the gas in the electrode laminated body 5 out of the exterior body 7. FIG. In this modification, the method for manufacturing the secondary battery 200 further includes a third sealing step of sealing the outer package 7 again after the first gas movement step and before the second charging step. . Thereby, the surplus volume in a 2nd gas movement process becomes smaller than the surplus volume in the gas movement process before charge. Accordingly, the joining portion 21 of the separator 4 is easily peeled off, and the pressure applied to the exterior body 7 in the second gas movement step is made smaller than the pressure applied to the exterior body 7 in the gas movement step before charging. Therefore, it is more effective to suppress peeling of the joint portion 21.

  In the present embodiment, the volume of the electrolytic solution 6 accommodated in the exterior body 7 is larger than the total pore volume in the electrode laminate 5. In this case, since the electrolytic solution 6 is present outside the electrode laminate 5 and inside the outer package 7, the empty space is reduced. Accordingly, the joining portion 21 of the separator 4 is easily peeled off, and the pressure applied to the exterior body 7 in the second gas movement step is made smaller than the pressure applied to the exterior body 7 in the gas movement step before charging. Therefore, it is more effective to suppress peeling of the joint portion 21.

  Moreover, in this embodiment, the pressure applied to the electrode laminated body 5 in a 2nd gas movement process is below half of the pressure applied to the electrode laminated body 5 in the gas movement process before charge. Thereby, peeling of the junction part 21 can be suppressed more reliably.

  Moreover, the pressure applied to the electrode laminated body 5 in a 2nd gas movement process is 1/4 or more of the pressure applied to the electrode laminated body 5 in the gas movement process before charge. Thereby, it becomes possible to suppress peeling of the joint portion 21 while suppressing a decrease in battery performance.

While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention without departing from the technical idea of the present invention.
For example, in the above embodiment, the electrolyte is a liquid, but the present invention is not limited to such an example. For example, the technique of the present invention can be applied to a secondary battery using a gel-like or solid electrolyte.

DESCRIPTION OF SYMBOLS 100,200 Secondary battery 2 Positive electrode 3 Negative electrode 4 Separator 5 Electrode laminated body 6 Electrolyte 7 Exterior body 8 Positive electrode terminal 9 Negative electrode terminal 21 Joint part

Claims (9)

A step of constructing a secondary battery by housing an electrode laminate and an electrolyte in which a positive electrode and a negative electrode are laminated via a separator, and sealing a peripheral portion of the exterior body;
A first charging step of charging the secondary battery;
After the first charging step, a first gas moving step of moving the gas in the electrode stack outside the electrode stack;
A second charging step of charging the secondary battery after the first gas transfer step;
After the second charging step, a second gas moving step of moving the gas in the electrode stack outside the electrode stack;
A method for manufacturing a secondary battery, comprising:   The method according to claim 1, further comprising a gas movement step before charging that moves the gas in the electrode stack to the outside of the electrode stack after the step of configuring the secondary battery and before the first charging step. The manufacturing method of the secondary battery as described. The separator protrudes in one direction from the positive electrode and the negative electrode,
The step of forming the secondary battery includes a step of joining the protruding portion of the separator to the outer package in addition to sealing the peripheral edge of the outer package.
In the second gas moving step and the gas moving step before charging, the electrode stack is pressed from above the outer package so that the gas in the electrode stack is out of the electrode stack and the space in the outer package. It is a process to move to
The method for manufacturing a secondary battery according to claim 2, wherein a pressure applied to the electrode stack in the second gas transfer step is smaller than a pressure applied to the electrode stack in the gas transfer step before the charging. The first gas moving step is a step of unsealing the outer body and moving the gas in the electrode stack to the outside of the outer body,
The method for manufacturing a secondary battery according to claim 3, further comprising a sealing step of sealing the exterior body again after the first gas movement step and before the second charging step. The electrolyte is an electrolytic solution containing an electrolyte,
5. The method of manufacturing a secondary battery according to claim 3, wherein a volume of the electrolytic solution accommodated in the exterior body is larger than a total volume of pores in the electrode stack.   The secondary battery according to any one of claims 3 to 5, wherein a bonding strength of a portion where the separator is bonded to the outer package is lower than a strength of a portion where the outer package is sealed at a peripheral edge. Manufacturing method.   The pressure applied to the electrode stack in the second gas transfer step is not more than half of the pressure applied to the electrode stack in the gas transfer step before the charging. Of manufacturing a secondary battery.   The secondary battery according to claim 7, wherein a pressure applied to the electrode stack in the second gas transfer step is equal to or more than a quarter of a pressure applied to the electrode stack in the gas transfer step before the charging. Manufacturing method.   The first gas moving step is a step of pressing the electrode stack from above the outer package to move the gas in the electrode stack outside the electrode stack to a space in the outer package. Item 4. A method for manufacturing a secondary battery according to Item 3.

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