JP2009199756A - Method of manufacturing lithium ion secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery improved in charge discharge cycle characteristics. <P>SOLUTION: A method of manufacturing lithium ion secondary battery includes a first sealing step of housing an electrode formed by laminating a positive electrode and a negative electrode through a separator into an outer packaging comprising multilayer laminate films and sealing the outer peripheral part of the outer packaging except a first electrolyte pouring opening peripheral part; a first electrolyte pouring step of pouring an electrolyte; a second sealing step of forming a second sealing part by leaving 10-30% of the first electrolyte pouring opening peripheral part as a second electrolyte pouring opening; a first standing step of standing for one day; a charging step; a second standing step of standing for two or three days; a discharge step; a second electrolyte pouring step of pouring the electrolyte 1.0-1.5 times of the difference between the battery weight after the first electrolyte pouring step and the battery weight after the discharge; and a third sealing step of forming a third sealing part by sealing the second electrolyte pouring opening under reduced pressure over 25-50% of the width of the second sealing part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a lithium ion secondary battery, in particular, a laminate film exterior type lithium ion secondary battery.

  Lithium ion secondary batteries that use lithium-containing composite oxides for the positive electrode and carbon materials, silicon materials, or lithium metals for the negative electrode can achieve a high energy density. Has attracted attention as a power source for hybrid vehicles and the like because of its high input / output characteristics.

  In particular, a laminated film exterior type lithium ion secondary battery using a multilayer laminate film mainly composed of a resin film having a metal foil, for example, an aluminum foil as an intermediate layer, as an exterior body is light in weight, excellent in heat dissipation, and has a shape flexibility. Attention is increasing from the height.

  However, in the lithium ion secondary battery, the charge and discharge, especially the electrolyte reacts with the electrode during the first charge to generate gas, the battery is swollen / deformed by the generated gas, and the charge / discharge reaction due to the stay of the generated gas between the electrodes. There is a possibility that the battery life may be shortened, such as a decrease in charge / discharge cycle characteristics due to an insufficient amount of the electrolytic solution accompanying the consumption of the electrolytic solution due to gas generation.

  As countermeasures against gas generation, for example, in Patent Document 1, after injection / sealing of an electrolyte, a charging process and a storage process at 60 ° C. in a charged state are performed, a part of the outer body is opened, and the generated gas is discharged. And the method of sealing again an opening part is disclosed.

  In Patent Document 2, charging is performed after electrolyte injection / temporary sealing, the temporary sealing part is removed, and the opening part is sealed again at less than atmospheric pressure, and the final sealing is performed by thermally bonding the laminate film, A method is disclosed in which a laminate film combines a container internal pressure holding and a pressure relief safety valve.

  Patent Document 3 discloses a method of performing preliminary charging after injecting an electrolytic solution and sealing an unsealed portion under reduced pressure, and a method of performing a step of injecting an insufficient amount of electrolytic solution before reducing pressure.

  Patent Documents 4 and 5 disclose a method in which an electrolytic solution is injected in two portions, and charging is performed between the first and second injection steps.

JP 2000-277144 A Japanese Patent No. 3997369 Japanese Patent No. 3778742 JP 2006-260864 A JP 2006-294282 A

  Conventionally disclosed methods are excellent as countermeasures against gas generation and methods for improving battery characteristics. However, the present invention is a lithium ion secondary battery in which further battery characteristics, particularly charge / discharge cycle characteristics are improved. It aims at providing the manufacturing method of.

  In order to achieve the above object, a method for producing a lithium ion secondary battery according to the present invention is a resin film-based multi-layer laminate having an electrode body in which a positive electrode and a negative electrode are laminated via a separator, and a metal foil as an intermediate layer. After being sandwiched and housed in an outer package made of a film, the outer periphery of the outer package is left in the state where the positive electrode lead portion and the negative electrode lead portion are projected to the outside of the outer package body, leaving the first injection port side portion. A first sealing step for sealing and a first liquid injection step for injecting an electrolytic solution from the first liquid injection port side, and 10 to 30% of the first liquid injection port side for the second time. A second sealing step for forming a second sealing portion to leave as a liquid injection port, a first stationary step for one day after the second sealing step, and the positive electrode after the first stationary step A charging step of charging through the lead part and the negative electrode lead part; 1.0 to 1.5 times the difference between the standing step, the discharging step after the second standing step, the battery weight after the first pouring step and the battery weight after the discharging step A second pouring step of injecting the electrolyte solution from the second pouring port, and sealing the second pouring port under reduced pressure over 25 to 50% of the sealing width of the second sealing portion. And a third sealing step for forming a third sealing portion.

  According to the present invention, it is possible to suppress battery swelling / deformation due to gas generation, inhibition / reduction of charge / discharge reaction, and deterioration of charge / discharge cycle characteristics due to shortage of electrolyte due to consumption of electrolyte due to gas generation. The location where the internal pressure is released when the internal pressure of the battery increases due to battery abnormality or the like is specified.

  Next, embodiments of the present invention will be described with reference to the drawings.

(Battery configuration according to the present invention)
1 to 4 are schematic plan views showing intermediate steps of an embodiment of a method for producing a lithium ion secondary battery according to the present invention. FIGS. 1 (a), 2 (a), and 3 (a). 4 (a) is the first sealing step, FIG. 1 (b), FIG. 2 (b), FIG. 3 (b) and FIG. 4 (b) are the second sealing step, FIG. 1 (c) and FIG. 2 (c), FIG. 3 (c), and FIG. 4 (c) show a third sealing step. FIG. 1 shows a lithium ion secondary battery in which a positive electrode lead and a negative electrode lead are led out from opposite sides, the electrode body is covered with two multilayer laminate films, and the surrounding four sides are sealed. FIG. Fig. 3 shows a lithium ion secondary battery in which a positive electrode lead and a negative electrode lead are led out, a multilayer laminate film is folded back to cover the electrode body, and three sides are sealed. Fig. 3 shows the positive electrode lead and the negative electrode lead from one side. Fig. 4 shows a lithium ion secondary battery in which one multilayer laminate film is folded to cover an electrode body and three sides are sealed, and Fig. 4 shows a positive electrode lead and a negative electrode lead from one side. A lithium ion secondary battery in which the electrode body is covered with two sheets and the four sides are sealed is shown.

  As shown in FIGS. 1 to 4, in the present invention, after the electrode body 1 is housed in the aluminum laminate film exterior body, the outer periphery of the exterior body with the positive electrode lead portion 2 and the negative electrode lead portion 3 protruding outside the exterior body body is shown. A first sealing step (see FIG. 1 (a), FIG. 2 (a), FIG. 3 (a), FIG. 4 (a)) for sealing the portion 4 leaving the first liquid injection side 5; The first liquid injection step of injecting the electrolytic solution from the first liquid inlet side 5 and the length of 10% to 30% of the first liquid inlet side 5 as the second liquid inlet 7 The second sealing step (see FIG. 1 (b), FIG. 2 (b), FIG. 3 (b), and FIG. 4 (b)) for forming the second sealing portion 6 to leave, and then let stand for one day. The first standing step, then the charging step of charging through the positive electrode lead portion 2 and the negative electrode lead portion 3, the second standing step of standing in a charged state for 2 to 3 days, and discharging after standing Electric discharge And a second injection in which an electrolyte solution of 1.0 to 1.5 times the difference between the battery weight after the first injection step and the battery weight after the discharge step is injected from the second injection port 7. From the liquid sealing step and the third sealing step of sealing the second liquid filling port 7 under reduced pressure over 25% to 50% of the sealing width of the second sealing portion 6 to form the third sealing portion 8. Composed.

  When the length of the side of the second liquid injection port 7 is made smaller than 10% of the first liquid injection port side 5 in the second sealing step of the present invention, the first standing step to the discharging step are performed. Electrolytic solution that cannot be sufficiently large as a gas outlet when discharging the generated gas, tends to remain inside the battery, and is injected when the electrolytic solution is injected in the second liquid injection step The inlet is not large enough, and it is difficult to inject the electrolyte, and it is not preferable because the electrolyte easily spills out of the battery. When it is larger than 30%, the gas generated from the first stationary step to the discharge step This is not preferable because the decrease in the electrolyte solution due to the volatilization of the solvent component of the electrolyte solution that occurs together with the discharge of the electrolyte increases and the charge / discharge reaction in the charging step and the discharging step does not proceed smoothly.

  In the first standing step of the present invention, when a standing period is not provided, it is not preferable because the electrolytic solution does not sufficiently reach the inside of the electrode body. The decrease in the electrolyte is not preferable because the charge / discharge reaction in the charging step and the discharging step is difficult to proceed smoothly.

  When the standing period is shorter than 2 days in the second standing step of the present invention, it is not preferable because the gas generated during the charging process cannot be sufficiently discharged and the gas tends to remain inside the battery. The volatilization amount of the solvent component of the electrolytic solution is increased, and the discharge reaction during the discharging process is difficult to proceed smoothly due to a decrease in the electrolytic solution.

  When the amount of electrolyte injected in the second injection step of the present invention is less than 1.0 times the difference between the battery weight after the first injection step and the battery weight after the discharge step, The amount of the liquid is not sufficient, and the charge / discharge reaction is difficult to proceed smoothly, and the charge / discharge cycle characteristics are liable to deteriorate, which is not preferred. Is liable to become a gas, and the battery is swollen / deformed by the generated gas, and the charge / discharge reaction is hindered / reduced due to gas retention between electrodes, and the charge / discharge cycle characteristics are liable to deteriorate.

  When the second injection port 7 is sealed narrower than 25% of the width of the second sealing portion 6 in the third sealing step of the present invention, the length of the sealing path from the inside of the battery to the outside is not sufficient. It is not preferable because the electrolyte solution is likely to ooze out from the third sealing portion 8. When the sealing is performed wider than 50%, the strength of the third sealing portion 8 is increased, and the third sealing portion 8 is increased when the battery internal pressure increases. This is not preferable because the possibility of opening other locations increases and it becomes difficult to specify the internal pressure release port when the battery internal pressure rises.

  Although the environmental temperature in the standing period of the present invention is not particularly limited, there is no particular problem when the environmental temperature is lower than 20 ° C., but cooling environment equipment or the like is necessary, and as the temperature decreases. When the mobility of lithium ions in the electrolytic solution gradually decreases and the temperature is higher than 40 ° C., the solvent component of the electrolytic solution is likely to volatilize, and the decrease in the electrolytic solution causes the charge / discharge reaction during the charging and discharging steps Since it becomes difficult to advance smoothly, it is preferable that the environmental temperature of a stationary period shall be 20 to 40 degreeC.

(Laminate film exterior)
The laminate film exterior body used in the present invention is not particularly limited as long as it is a multilayer laminate film mainly composed of a resin film having a metal foil as an intermediate layer, but aluminum foil is used as the metal foil from the viewpoint of ease of shape processing. Is preferable.

(Electrode body / Positive electrode)
As the positive electrode constituting the electrode body of the present invention, a normal positive electrode for a lithium ion secondary battery can be used. For example, as the positive electrode active material, lithium-containing composite oxides such as LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiNi _0.5 Mn _1.5 O ₄ , LiFePO _4, etc. The transition metal portion of these lithium-containing composite oxides may be substituted with other elements, or a mixture thereof. These positive electrode active materials in a solvent such as N-methyl-2-pyrrolidone (NMP) capable of dissolving the binder together with a conductivity imparting agent such as carbon black and a binder such as polyvinylidene fluoride (PVdF). The mixture is dispersed and kneaded, applied onto a current collector such as an aluminum foil, and the positive electrode is formed by a method such as drying the solvent.

(Electrode / Negative electrode)
As the negative electrode constituting the electrode body of the present invention, a normal negative electrode for a lithium ion secondary battery can be used. For example, examples of the negative electrode active material include lithium metal, or a material that can occlude and release lithium, such as a graphite material, an amorphous carbon material, a silicon material, and a silicon compound material, or a mixture thereof. These negative electrode active materials are dispersed and kneaded together with a conductivity-imparting agent made of carbon black or the like and a binder made of PVdF or the like in a solvent such as NMP that can dissolve the binder, and this is collected into a copper foil or the like. The negative electrode is formed by a method such as coating on an electric body and drying the solvent.

(Electrode body / Separator)
The separator which comprises the electrode body of this invention can use the normal separator for lithium ion secondary batteries. For example, a woven fabric, a non-woven fabric, a porous membrane, and the like can be used. In particular, a polypropylene or polyethylene-based porous membrane is preferably used in terms of a thin film and a large area, membrane strength, and membrane resistance.

(Electrolyte)
As the electrolytic solution used in the present invention, a normal electrolytic solution for a lithium ion secondary battery can be used. For example, the non-aqueous solvent lithium salt can be used a nonaqueous electrolyte solution obtained by dissolving as an electrolyte, a lithium salt, lithium imide _{salt, LiPF 6, LiAsF 6, LiAlCl} 4, LiClO 4, LiBF 4, LiSbF 6 In particular, LiPF ₆ and LiBF ₄ are preferably used. Examples of the lithium imide salt include LiN (C _k F _{2k + 1} SO ₂ ) (C _m F _{2m + 1} SO ₂ ) (k and m are each independently 1 or 2), and these lithium salts Can also be used in combination.

  As the non-aqueous solvent, at least one kind selected from cyclic carbonates, chain carbonates, aliphatic carboxylic acid esters, γ-lactones, cyclic ethers, chain ethers, and organic solvents thereof. The organic solvent is used. More specifically, cyclic carbonates: propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and derivatives thereof, chain carbonates: dimethyl carbonate (DMC), diethyl carbonate (DEC), Ethyl methyl carbonate (EMC), dipropyl carbonate (DPC), and derivatives thereof, aliphatic carboxylic acid esters: methyl formate, methyl acetate, ethyl propionate, and derivatives thereof, γ-lactones: γ-butyrolactone, And its derivatives, cyclic ethers: tetrahydrofuran, 2-methyltetrahydrofuran, chain ethers: 1, 2-ethoxyethane (DEE), ethoxymethoxyethane (EME), diethyl ether, and derivatives thereof, others: dimethyl Sulfoxide, 1,3-dioxolane, formamide, acetamide, dimethylformamide, dioxolane, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, phosphoric acid triester, trimethoxymethane, dioxolane derivative, sulfolane, methylsulfolane, 1,3- Dimethyl-2-imidazolidinone, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, 1,3-propane sultone, anisole, N-methylpyrrolidone, fluorinated carboxylic acid ester Two or more kinds can be mixed and used.

  Furthermore, it is also possible to use common, for example, vinylene carbonate (VC) as the electrolyte solution additive.

(Preparation of positive electrode)
A positive electrode active material (LiMn ₂ O ₄ ) and a conductivity-imparting agent (carbon black) were mixed and dispersed uniformly in NMP in which a binder (PVdF) was dissolved to prepare a slurry. The slurry was applied on a positive electrode current collector (aluminum foil, thickness 20 μm), NMP was evaporated, and then pressed to produce a positive electrode.

  The solid content ratio in the positive electrode was positive electrode active material: conductivity imparting agent: binder = 90: 5: 5 (wt%). The positive electrode was cut into a slurry uncoated portion 20 mm, a coated portion 200 mm, and a short axis direction 100 mm in the major axis direction, and a positive electrode lead was attached to the slurry uncoated portion.

(Preparation of negative electrode)
A negative electrode active material (graphite material) and a conductivity-imparting agent (carbon black) were mixed and uniformly dispersed in NMP in which a binder (PVdF) was dissolved to prepare a slurry. The slurry was applied on a negative electrode current collector (copper foil, thickness 15 μm), NMP was evaporated, and then pressed to prepare a negative electrode.

  The solid content ratio in the negative electrode was negative electrode active material: conductivity imparting agent: binder = 89: 1: 10 (wt%). The negative electrode was cut into a slurry uncoated portion 20 mm, a coated portion 210 mm, and a minor axis direction 110 mm in the major axis direction, and a positive electrode lead was attached to the slurry uncoated portion.

(Production of electrode body)
The positive electrode is sandwiched between the negative electrode through a separator (long-axis method 220 mm, short-axis direction 120 mm, thickness 25 μm) having a two-layer structure of polyethylene and polypropylene, so that the positive electrode lead and the negative electrode lead face in opposite directions. The electrode body which laminated | stacked and consists of 10 sheets of positive electrodes, 11 sheets of negative electrodes, and 20 sheets of separators was produced.

(Electrolyte)
As the electrolytic solution, EC: DEC = 40: 60 (vol%) in which 1 mol / L LiPF ₆ as an electrolyte was dissolved was used.

(Laminate film exterior)
The laminate film exterior body uses an aluminum laminate film having a structure in which polypropylene (fused layer, thickness 70 μm), polyethylene terephthalate (thickness 20 μm), aluminum (thickness 50 μm), and polyethylene terephthalate (thickness 20 μm) are laminated in this order. Two sheets are cut out to a predetermined size, and a concave portion having a bottom surface portion and a side surface portion that match the size of the electrode body is formed in a part thereof, and the electrode body can be accommodated in the concave portion by facing them. .

(Battery assembly)
The electrode body was housed in an exterior body made of an aluminum laminate film, and the outer periphery was sealed leaving the first liquid injection port side in a state where the positive electrode lead portion and the negative electrode lead portion were projected to the outside of the exterior body (first One sealing step: see FIG. 1 (a)). 30 g of electrolyte was injected from the side of the first injection port (first injection step). A part of the first liquid injection port side was left as the second liquid injection port, the opening was sealed (second sealing step: see FIG. 1 (b)), and left for 1 day (first Standing step). The battery was charged for 15 hours by a constant current constant voltage charging method having a constant current of 0.5 A and a final voltage of 4.3 V (charging step). It left still for the period of Table 1 in the charging state (2nd standing process). The battery was discharged to a final voltage of 3.0 V by a 0.5 A constant current discharge method (discharge process). The multiple electrolytes listed in Table 1 were injected from the second injection port with respect to the difference between the battery weight after the first injection step and the battery weight after the discharge step (second injection step). Under reduced pressure, the second liquid injection port was sealed at the ratio (%) shown in Table 1 with respect to the width of the second sealing portion (third sealing step) to produce a lithium ion secondary battery. . The values for each step of the comparative example are also shown in Table 1.

(Charge / discharge cycle test)
At 25 ° C., charging is performed at a constant current of 4.5 A and a constant current constant voltage charging method with a termination voltage of 4.2 V for 3 hours. The charge / discharge cycle test was conducted, and the value obtained by dividing the discharge capacity after 1000 cycles by the discharge capacity at the first cycle is shown in Table 1 as the discharge capacity retention rate (%).

  The value obtained by dividing the battery volume after 1000 cycles by the battery volume at the first cycle is shown in Table 1 as the volume change rate (%).

(Effect of the second sealing process)
Comparing Examples 1 to 2 and 9 to 10 with Comparative Examples 1 to 6, when the second liquid injection port is not provided in the second sealing step (Comparative Examples 1 to 2), discharging in the charge / discharge cycle A decrease in capacity maintenance rate and an increase in volume were observed, and it was confirmed that the second liquid injection port in the second sealing step was necessary. In addition, when the length of the second liquid injection port is outside the range of the present invention (Comparative Examples 3 to 6), a decrease in the discharge capacity maintenance rate of the charge / discharge cycle and an increase in the volume were observed. In the case where it is smaller than the range (Comparative Examples 3 to 4), it is considered that the charge / discharge cycle characteristics are reduced as a result of the increase in the battery volume due to the large amount of residual gas in the battery. In Comparative Examples 5 to 6), it is considered that the charge / discharge reaction was lowered as a result of adhesion of residues or the like to the electrode surface or the like with the volatilization of the solvent component of the electrolytic solution. From the results, it was confirmed that the second sealing step of the present invention was necessary and the range was appropriate.

(Effect of the first stationary process)
When Examples 1-2 and Comparative Examples 7-10 are compared, when not providing a stationary period (Comparative Examples 7-8), when longer than the range of this invention (Comparative Examples 9-10), it is a charge / discharge cycle. A decrease in the discharge capacity retention rate was observed. In Comparative Examples 7-8, it is considered that the effect that the initial charging / discharging reaction does not proceed smoothly because the electrolyte solution does not sufficiently reach the inside of the electrode body was also reflected during the charging / discharging cycle. In this case, it is considered that the charge / discharge reaction is reduced as a result of adhesion of residues or the like to the electrode surface or the like as the solvent component of the electrolytic solution is volatilized. From the said result, it confirmed that the range of the 1st stationary process of this invention was appropriate.

(Effect of the second stationary process)
When Examples 1-8 are compared with Comparative Examples 11-14, when the standing period is shorter than the range of the present invention (Comparative Examples 11-12), when it is longer than the range of the present invention (Comparative Examples 13-14) In both cases, a decrease in the discharge capacity maintenance rate and an increase in the volume of the charge / discharge cycle were observed. In Comparative Examples 11-12, it is considered that the charge / discharge cycle characteristics were reduced as a result of the increase in the battery volume due to the large amount of residual gas in the battery. In Comparative Examples 13-14, along with the volatilization of the solvent component of the electrolyte solution This is thought to be because the charge / discharge reaction was reduced as a result of adhesion of residues to the electrode surface and the like. From the said result, it confirmed that the range of the 2nd stationary process of this invention was appropriate.

(Effect of the second injection process)
When Examples 1-4 and Comparative Examples 15-18 are compared, when the amount of electrolyte solution is less than the range of this invention (Comparative Examples 15-16), the fall of the discharge capacity maintenance factor of a charging / discharging cycle is observed, this book When more than the scope of the invention (Comparative Examples 17-18), an increase in volume was observed. In Comparative Examples 15 to 16, it is considered that the amount of the electrolyte in the battery was not sufficient, and the charge / discharge reaction was difficult to proceed smoothly. In Comparative Examples 17 to 18, the excess electrolyte became gas. Conceivable. From the said result, it confirmed that the range of the 2nd injection process of this invention was appropriate.

(Effect of the third sealing process)
When Examples 1-2 and Comparative Examples 19-20 are compared, although a big difference is not seen with both the discharge capacity maintenance factor of a charging / discharging cycle, and a volume change, when it is narrower than the scope of the present invention (Comparative Example 19), When the deposit of the deposit considered to be leached out of the electrolyte solution is observed in the third sealing portion and is wider than the range of the present invention (Comparative Example 20), the batteries of Examples 1 and 2 and Comparative Example 20 When the battery was forcedly inflated using 5 each, the batteries of Examples 1 and 2 were all opened by the third sealing portion, but in Comparative Example 20, Locations other than the third sealing portion of the individual batteries opened, making it difficult to specify the internal pressure release port when the internal pressure of the battery increased. From the said result, it confirmed that the range of the 3rd sealing process of this invention was appropriate.

  From the above results, it was confirmed that the battery produced using the production method of the present invention was excellent in charge / discharge cycle characteristics, and that the internal pressure release port when the battery internal pressure increased could be specified.

The schematic plan view which shows the intermediate | middle process of one Embodiment of the manufacturing method of the lithium ion secondary battery of this invention. The schematic plan view which shows the intermediate | middle process of one Embodiment of the manufacturing method of the lithium ion secondary battery of this invention. The schematic plan view which shows the intermediate | middle process of one Embodiment of the manufacturing method of the lithium ion secondary battery of this invention. The schematic plan view which shows the intermediate | middle process of one Embodiment of the manufacturing method of the lithium ion secondary battery of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode body 2 Positive electrode lead part 3 Negative electrode lead part 4 Outer peripheral part 5 1st liquid injection port side part 6 2nd sealing part 7 2nd liquid injection port 8 3rd sealing part

Claims (1)

  An electrode body formed by laminating a positive electrode and a negative electrode through a separator is sandwiched and stored by an outer package made of a resin film-based multilayer laminate film having a metal foil as an intermediate layer, and then a positive electrode lead portion and a negative electrode From the first sealing step of sealing the outer peripheral portion of the exterior body with the lead portion protruding outside the exterior body, leaving the first liquid injection port side, and the first liquid injection port side A first injection step of injecting an electrolytic solution, and a second sealing step of forming a second sealing portion leaving 10 to 30% of the first injection port side as a second injection port A first standing step for standing for one day after the second sealing step, a charging step for charging through the positive lead portion and the negative lead portion after the first standing step, and 2 to 3 in a charged state. A second standing step for standing for one day, a discharging step for discharging after the second standing step, and the first infusion process A second injection step of injecting an electrolyte solution of 1.0 to 1.5 times the difference between the subsequent battery weight and the battery weight after the discharge step from the second injection port; And a third sealing step of forming a third sealing part by sealing the second liquid inlet over 25 to 50% of the sealing width of the second sealing part. Battery manufacturing method.

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