JP2003059538A - Manufacturing method of cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a cell of large energy density and output density which gives birth to excellent charge/discharge cycle characteristics. SOLUTION: A secondary cell provided with a positive electrode and a negative electrode as well as an electrolyte layer is assembled (a step S110). After that, the secondary cell is charged as it is pressurized (a step S120). Or, after the secondary cell is charged under normal pressure, it may be stored in a pressurized state. Further, after the secondary cell is charged as it is pressurized, it may be stored in a pressurized state. With this, the negative electrode is prevented from getting in an overvoltage state, and a coating is properly formed on the surface of the negative electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a battery including a step of assembling the battery and then charging the battery.

[0002]

2. Description of the Related Art In recent years, portable electronic devices have been developed one after another, and batteries have come to play an important role as a power source for them. Since portable electronic devices are required to be small and lightweight, the battery must be
It is required to be small and lightweight. Further, in order to efficiently use the storage space of the electronic device, a device having a large degree of freedom in shape is required. As a battery satisfying such requirements, a lithium secondary battery having a large energy density and a high output density, or a lithium ion secondary battery using a carbon material capable of reversibly inserting and extracting lithium ions in the negative electrode is used. is there. Among them, the lithium-ion secondary battery has been widely put into practical use, and its application is expanding mainly in portable electronic devices such as camcorders, notebook computers and mobile phones.

[0003]

However, the lithium secondary battery and the lithium ion secondary battery have a problem that the discharge capacity gradually decreases due to repeated charging and discharging. This may be due to the deterioration of the performance of the materials constituting the battery, for example, the positive electrode material, the conductive agent, the binder or the electrolyte, but in most cases, it is due to the reaction between the negative electrode and the electrolyte. Since the negative electrode becomes a strong reducing agent in the charged state, it easily reacts with the electrolyte. When the negative electrode in the charged state reacts with the electrolyte, it means that the negative electrode is self-discharged, which causes a deviation from the charging depth of the positive electrode. Since it is not possible to charge or discharge only one of the positive and negative electrodes inside the battery, the shift in the depth of charge between the positive and negative electrodes causes an irrecoverable decrease in capacity. Further, when the negative electrode and the electrolyte react with each other, the negative electrode may be denatured or disintegrated to be deactivated and the capacity may be reduced.

Such a reaction between the negative electrode and the electrolyte is suppressed by the passivation film formed on the surface of the negative electrode by reductive decomposition of the electrolyte during charging. However, when the negative electrode in the charged state reacts with the electrolyte, the electrolyte is reductively decomposed to form a passivation film on the surface of the negative electrode, and a minute gas is generated, which causes an overvoltage on a part of the negative electrode surface that occludes lithium. A film may be excessively formed, or lithium metal may be deposited in a lithium ion secondary battery.

If the film is excessively formed, the difference in the charging depth between the positive and negative electrodes becomes large, and the capacity of the battery decreases by the amount of the deviation. Further, the internal resistance of the battery increases due to the resistance of the formed coating film, so that the battery performance deteriorates. Furthermore,
When lithium metal is deposited on the negative electrode in the lithium ion secondary battery, the lithium metal reacts with the electrolyte to passivate it, reducing the reaction surface of the negative electrode, resulting in a decrease in battery performance.

The film on the surface of the negative electrode is formed only after the battery is assembled for the first time during the initial charge and during the storage period until the battery is discharged. Therefore, the initial charge method and the storage method are very important problems in controlling the film formation. Is.

The present invention has been made in view of the above problems, and an object thereof is to obtain an excellent charge / discharge cycle characteristic with large energy density and output density by optimizing a charging method or a storage method. Another object of the present invention is to provide a method of manufacturing a battery that can be manufactured.

[0008]

The method of manufacturing a battery according to the present invention includes the steps of assembling a battery having an electrolyte together with a positive electrode and a negative electrode, and charging the assembled battery under pressure.

Another method for manufacturing a battery according to the present invention comprises the steps of assembling a battery having an electrolyte together with a positive electrode and a negative electrode, charging the assembled battery, and storing the charged battery under pressure. Is included.

In the method of manufacturing a battery according to the present invention or another method of manufacturing a battery, the battery is charged under pressure, or the battery is charged and then stored under pressure. An overvoltage state is prevented and a good quality film is properly formed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] FIG. 1 shows a first embodiment of the present invention.
FIG. 6 shows steps of the method for manufacturing the battery according to the embodiment of FIG. 2 is an exploded view of the secondary battery 1 manufactured using the battery manufacturing method shown in FIG.
2 shows a cross-sectional structure taken along line II of the battery element 20 shown in FIG. Note that, here, a case of manufacturing a battery using lithium (Li) as an electrode reactive species will be described.

First, the secondary battery 1 shown in FIGS. 2 and 3.
Are assembled (step S110). The process of assembling the secondary battery 1 is a process of manufacturing the positive electrode 21 (step S1
11), a step of producing the negative electrode 22 (step S11
2), a step of forming the electrolyte layer 23 (step S11
3), a step of forming the battery element 20 (step S11
4) and the step of encapsulating the battery element 20 inside the exterior members 30a and 30b (step S115).
First, for example, a positive electrode material, a conductive agent such as carbon black or graphite, and a binder such as polyvinylidene fluoride are mixed to prepare a positive electrode mixture, which is dispersed in a solvent such as N-methyl-2-pyrrolidone. Then, a positive electrode mixture slurry is prepared. Examples of the positive electrode material include metal oxides such as V ₂ O _{5 and} lithium composite oxides, metal sulfides such as TiS _{2 and} MoS ₂ , and polymer materials such as polyacetylene and polypyrrole. You may use 1 type or in mixture of 2 or more types.

Above all, it is preferable to use a lithium composite oxide because the voltage can be increased and the energy density can be increased. Examples of this lithium composite oxide include those represented by the chemical formula Li _x MO ₂ . In the formula, M is preferably at least one transition metal element, particularly at least one of cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe). The value of x depends on the charge / discharge state of the battery,
Usually, 0.05 ≦ x ≦ 1.10. Specific examples of such a lithium composite oxide include LiCO ₂ and LiN.
i _y Co _1-y O ₂ (where 0 <y <1) or LiM
such as n ₂ O ₄ and the like. In addition to these positive electrode materials, LiFePO ₄ or NbSe ₂ may be used.

After preparing the positive electrode mixture slurry, for example, the positive electrode mixture slurry is treated with aluminum (Al) foil,
The positive electrode current collector layer 21a made of a metal foil such as nickel (Ni) foil or stainless steel foil is coated on both sides or one side, dried, and compression molded to form a positive electrode mixture layer 21b.
The positive electrode 21 is produced (step S111). At this time,
The positive electrode mixture slurry is not applied to one end of the positive electrode current collector layer 21a, but the end is exposed.

Then, for example, a negative electrode material capable of inserting and extracting lithium and a binder such as polyvinylidene fluoride are mixed to prepare a negative electrode mixture, and N-methyl-
Disperse in a solvent such as 2-pyrrolidone to obtain a negative electrode mixture slurry. Examples of the negative electrode material capable of occluding / releasing lithium include a simple substance, an alloy or a compound of a metal element or a semi-metal element capable of forming an alloy with lithium. The alloy includes not only an alloy composed of two or more kinds of metal elements but also an alloy composed of one or more kinds of metal elements and one or more kinds of metalloid elements. Its structure is solid solution, eutectic (eutectic mixture), intermetallic compound or 2
Some species and more coexist.

Examples of such metal or metalloid elements are tin (Sn), lead (Pb), aluminum, indium (In), silicon (Si), zinc (Z).
n), antimony (Sb), bismuth (Bi), gallium (Ga), germanium (Ge), arsenic (As), silver (Ag), hafnium (Hf), zirconium (Zr).
And yttrium (Y). As these alloys or compounds, for example, chemical formulas Ma _s Mb _t
Examples include Li _u and those represented by the chemical formula Map _p Mc _q Md _r . In these chemical formulas, Ma represents at least one kind of metal element and metalloid element capable of forming an alloy or compound with lithium, and Mb represents at least one kind of metal element and metalloid element other than lithium and Ma. , Mc represents at least one kind of non-metal element, and Md represents at least one kind of metal element and metalloid element other than Ma. Also, s, t,
The values of u, p, q and r are s> 0, t ≧ 0 and u, respectively.
≧ 0, p> 0, q> 0, r ≧ 0.

Among them, simple substances, alloys or compounds of 4B group metal elements or metalloid elements are preferable, and particularly preferable are silicon or tin, or alloys or compounds thereof. These may be crystalline or amorphous.

For such alloys or compounds
Physically, for example, LiAl, AlSb, CuMgS
b, SiB_Four, SiB₆, Mg₂Si, Mg₂Sn, N
i₂Si, TiSi₂, MoSi₂, CoSi₂, Ni
Si₂, CaSi₂, CrSi₂, Cu_FiveSi, FeS
i₂, MnSi₂, NbSi₂, TaSi₂, VS
i ₂, WSi₂, ZnSi₂, SiC, Si₃N_Four, S
i₂N₂O, SiO_v(0 <v ≦ 2), SnO_w(0 <
w ≦ 2), SnSiO₃, LiSiO or LiSn
There is O etc.

As the negative electrode material capable of sucking / releasing lithium, carbon materials, metal oxides, polymer materials and the like can also be mentioned. Examples of the carbon material include pyrolytic carbons, cokes, graphites, glassy carbons, organic polymer compound fired bodies, carbon fibers, and activated carbon. Among these, the cokes include pitch coke, needle coke, petroleum coke, and the like. The organic polymer compound fired body is carbonized by firing a polymer material such as phenol resin or furan resin at an appropriate temperature. The carbon fibers include mesocarbon microbeads and mesophase carbon fibers. Examples of the metal oxide include iron oxide, ruthenium oxide, molybdenum oxide, and the like, and examples of the polymer material include polyacetylene, polypyrrole, and the like. As the negative electrode material capable of inserting and extracting lithium, any one of these or a mixture of two or more may be used.

After the negative electrode mixture slurry is prepared, this negative electrode mixture slurry is applied to, for example, both surfaces or one surface of the negative electrode current collector layer 22a made of a metal foil such as copper (Cu) foil, nickel foil or stainless steel foil, and dried. Then, compression molding is performed to form the negative electrode mixture layer 22b, and the negative electrode 22 is manufactured (step S112). At this time, the negative electrode mixture is not applied to one end of the negative electrode current collector layer 22a, but the end is exposed.

After producing the negative electrode 22, the positive electrode current collector layer 2
The positive electrode lead wire 11 and the negative electrode current collector layer 2 on the exposed portion of 1a
The negative electrode lead wires 12 are attached to the exposed portions of 2a by resistance welding or ultrasonic welding, respectively. After that, for example, the positive electrode mixture layer 21b and the negative electrode mixture layer 22b
An electrolyte layer 23, which is an electrolyte, is formed thereon (step S113). The electrolyte layer 23 is prepared by, for example, dissolving a lithium salt that is an electrolyte salt in a non-aqueous solvent to prepare an electrolytic solution, and then preparing the electrolytic solution, the polymer material, and dimethyl carbonate that is the solvent for the polymer material. It is formed by mixing, coating the mixture on the positive electrode mixture layer 21b or the negative electrode mixture layer 22b, drying, and volatilizing the solvent.

As the lithium salt, for example, LiP
F ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃
SO ₂ ) ₂ or LiN (C ₂ F ₅ SO ₂ ) ₂ may be mentioned, and any one of these may be used, or two or more thereof may be mixed and used.

As the non-aqueous solvent, for example, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, dibutyl carbonate, butyl methyl carbonate, butyl ethyl carbonate, Butylpropyl carbonate or those obtained by substituting hydrogen atoms of these carbonic acid esters with halogen atoms, γ-butyrolactone, dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-
Examples include dioxolane, 4-methyl-1,3-dioxolane, diethyl ether, sulfolane, methylsulfolane, methylsulfolane butyrate, acetonitrile, propionnitrile or methyl propionate, and any one or a mixture of two or more of these may be used. You may use it.

As the polymer material, for example, polyvinylidene fluoride, polyacrylonitrile, polyethylene oxide, polypropylene oxide or polymethacrylonitrile can be mentioned.
You may use it in mixture of 2 or more types.

After forming the electrolyte layer 23, for example, as shown in FIG. 3, a separator 24, a positive electrode 21 having the electrolyte layer 23 formed thereon, a separator 24, and a negative electrode 22 having the electrolyte layer 23 formed thereon are sequentially laminated and wound. The battery element 20 is formed by, for example, adhering the protective tape 25 to the outermost peripheral portion (step S114).

As the separator 24, for example, a porous film made of a polyolefin material such as polypropylene or polyethylene, or a porous film made of an inorganic material such as a ceramic nonwoven fabric is used.
You may laminate | stack and use a porous film of 1 or more types.

After the battery element 20 is formed, for example, exterior members 30a and 30b made of an aluminum laminate film obtained by laminating a polyolefin film, an aluminum foil and a polyolefin film in this order are prepared, and the battery element 20 is sandwiched between them, and a reduced pressure atmosphere The outer packaging members 30a and 30b are pressure-bonded to the battery element 20, and the outer edge portions of the outer packaging members 30a and 30b are sealed by heat fusion or the like (step S115).
At that time, for example, the adhesion film 31 is provided between the positive electrode lead wire 11 and the negative electrode lead wire 12 and the exterior members 30a and 30b.
And insert the positive electrode lead wire 1 from the exterior members 30a and 30b.
1 and the negative electrode lead wire 12 are led out. The adhesive film 31 ensures insulation by preventing short circuit between the burr of the positive electrode lead wire 11 and the negative electrode lead wire 12 and the exterior members 30a and 30b, and at the same time, the positive electrode lead wire 1
1 and the negative electrode lead wire 12 and the exterior members 30a and 30b for improving the adhesiveness. This completes the assembly of the secondary battery 1.

After assembling the secondary battery 1, the secondary battery 1
With a pressure greater than atmospheric pressure applied to the secondary battery 1
Is charged (step S120). The pressurization suppresses the generation of minute gas even at a charge depth close to full charge where the reactivity of the negative electrode 22 becomes extremely high, and the negative electrode 22
This is because it is possible to prevent an overvoltage from occurring and to properly form a coating film on the surface of the negative electrode 22.

The pressure is applied by, for example, uniaxial pressure.
That is, as shown in FIG. 4, the two pressure plates 41 covering the buffer body 40 are pressed from above and below the secondary battery 1. As the buffer 40, for example, an elastic polymer material such as silicone rubber or cloth can be used. As the pressure plate 41, for example, a stainless plate, a glass plate, or a ceramic plate can be used.

The pressurization may be carried out by an isotropic pressurizing means such as a hydrostatic press. That is, as shown in FIG. 5, the hydrostatic pressure generating medium 50 may uniformly apply pressure to the secondary battery 1 from all directions. As the hydrostatic pressure generating medium 50, for example, an inert gas such as argon or a liquid substance such as water, insulating oil or liquid synthetic resin can be used.

The pressure applied in this way is 1.
The range is preferably 11 × 10 ⁵ Pa or more and 9.91 × 10 ⁶ Pa or less, and more preferably 1.50 × 10 ⁵ Pa or more and 2.06 × 10 ⁶ Pa or less. This is because a higher effect can be obtained within these ranges.

Charging may be performed by any method such as a constant current charging method of charging with a constant current value, a constant voltage charging method of charging with a constant voltage, or a constant current constant voltage charging method combining these.

Through the above steps, the secondary battery 1 is completed.

As described above, according to this embodiment, since the secondary battery 1 is charged under pressure, the negative electrode 2
The generation of minute gas can be suppressed even at a charge depth close to full charge at which the reactivity of No. 2 becomes extremely high.
2 can be prevented from becoming an overvoltage state. Therefore, the coating film can be properly formed. As a result, high energy density and high output density can be obtained, and battery characteristics such as charge / discharge cycle characteristics can be improved.

[Second Embodiment] FIG. 6 shows a second embodiment of the present invention.
FIG. 6 shows steps of the method for manufacturing the battery according to the embodiment of FIG. In the present embodiment, first, the secondary battery 1 is assembled in the same manner as in the first embodiment (step S11).
0). After that, the secondary battery 1 is charged, for example, under normal pressure (step S130). Charging may be performed by any method such as a constant current charging method, a constant voltage charging method or a constant current constant voltage method. Next, the secondary battery 1 is pressurized, and the secondary battery 1 is stored in this state (step S140). At that time, the pressurizing condition is the same as that in the charging in the first embodiment. As a result, the minute gas generated at the charging depth close to the fully charged state is released from the inside of the battery, and the negative electrode 22 is prevented from being in the overvoltage state as in the first embodiment.

The storage time is preferably 1 hour or more and 500 hours or less, more preferably 1 hour or more and 240 hours or less. This is because if the storage time is short, the charge / discharge cycle characteristics may be deteriorated, and if the storage time is long, the production efficiency is reduced.

According to the present embodiment, since the secondary battery 1 is stored while being pressurized, minute gas generated at a charge depth close to a fully charged state can be discharged from the inside of the battery. As in the first embodiment, it is possible to prevent the negative electrode 22 from becoming overvoltage.

[Third Embodiment] FIG. 7 shows a third embodiment of the present invention.
FIG. 6 shows steps of the method for manufacturing the battery according to the embodiment of FIG. In the present embodiment, first, the secondary battery 1 is assembled in the same manner as in the first embodiment (step S110).
After that, similarly to the first embodiment, the secondary battery 1
Is charged under pressure (step S120). Then, as in the second embodiment, the secondary battery 1 is stored in a pressurized state (step S140).

According to the present embodiment, since it includes both the steps of the first embodiment and the steps of the second embodiment, a higher effect can be obtained.

[0041]

EXAMPLES Further, specific examples of the present invention will be described in detail with reference to FIGS. 1, 2, 3, 6 and 7.

(Examples 1 to 6) First, 92% by mass of lithium cobalt oxide (LiCoO ₂ ) as a positive electrode material, 5% by mass of powdery graphite as a conductive agent, and powdery polyfluoride as a binder. 3% by mass of vinylidene chloride was mixed to prepare a positive electrode mixture. Then, this positive electrode mixture is dispersed in N-methyl-2-pyrrolidone which is a solvent to form a positive electrode mixture slurry, which is evenly applied to both sides of the positive electrode current collector layer 21a made of an aluminum foil, and the temperature is raised to 100 ° C. And dried under reduced pressure for 24 hours. Next, the positive electrode mixture layer 21b was formed by compression molding with a roll press and cut into a width of 50 mm and a length of 300 mm to produce the positive electrode 21 (see FIG. 1; step 111).

91% by mass of artificial graphite, which is the negative electrode material
And 9% by mass of powdered polyvinylidene fluoride as a binder were mixed to prepare a negative electrode mixture. Then, this negative electrode mixture is dispersed in N-methyl-2-pyrrolidone which is a solvent to obtain a negative electrode mixture slurry, and a negative electrode current collector layer 2 made of copper foil is formed.
It was evenly applied to both sides of 2a and dried under reduced pressure at 120 ° C. for 24 hours. Next, the negative electrode mixture layer 22b is formed by compression molding with a roll press, and has a width of 52 mm and a length of 32.
The negative electrode 22 was produced by cutting it to 0 mm (see FIG. 1; step S112).

Further, LiPF ₆ was dissolved in a solvent prepared by mixing 60% by volume of ethylene carbonate and 40% by volume of propylene carbonate at a concentration of 0.9 mol / kg with respect to the solvent to prepare an electrolytic solution. After that, this electrolytic solution, polyvinylidene fluoride which is a copolymer containing less than 7.7% by mass of hexafluoropropylene, and dimethyl-carbonate which is a solvent of a polymer material are mixed and stirred,
An electrolyte was prepared.

After the positive electrode 21, the negative electrode 22 and the electrolyte are prepared, the positive electrode lead wire 11 is attached to the positive electrode current collector layer 21a, and the electrolyte is applied on the positive electrode mixture layer 21b to volatilize dimethyl carbonate to form the electrolyte. The layer 23 was formed (FIG. 1; see step S113). Further, the negative electrode lead wire 12 was attached to the negative electrode current collector layer 22a, an electrolyte was applied on the negative electrode mixture layer 22b, and dimethyl carbonate was volatilized to form the electrolyte layer 23 (see FIG. 1; step S113). . Subsequently, a separator 24 made of a microporous polypropylene film was prepared, the separator 24, the positive electrode 21, the separator 24, and the negative electrode 22 were laminated in this order, wound flat, and a protective tape 25 was adhered to form a battery element 20 ( See FIG. 1; step S114).

After forming the battery element 20, armor members 30a and 30b made of an aluminum laminated film are prepared, and an adhesive film 31 is disposed between the positive electrode lead wire 11 and the negative electrode lead wire 12 and the armor members 30a and 30b. Then, the battery element 20 is vacuum-packed (FIG. 1; Step S11
5), the secondary battery 1 was assembled (FIG. 1; Step S).
110).

After assembling the secondary battery 1, the secondary battery 1
Was charged for the first time under pressure (Fig. 1; Step S12
0). At that time, pressure was applied by uniaxial pressure using a stainless steel plate coated with a silicon rubber sheet, and the pressure was changed as shown in Table 1 in Examples 1 to 6. Charging is performed at a constant current of 500 mA until the battery voltage reaches 4.25 V, and then at a constant voltage of 4.25 V, the current value is 5 m.
It went until it attenuated to A. Thereby, the secondary batteries 1 of Examples 1 to 6 were obtained.

[0048]

[Table 1]

Examples 1 to 1 of the state of charge thus obtained
Regarding the secondary battery 1 of 6, after a pause of 1 hour,
The battery was discharged at a constant current of 100 mA until the battery voltage reached 3.00 V, and the initial discharge capacity was measured. The results obtained are shown in Table 1. Further, after measuring the initial discharge capacity, a charge / discharge test was performed to obtain the discharge capacity retention rate. At that time, charging was performed at a constant current of 500 mA until the battery voltage reached 4.20 V, and then at a constant voltage of 4.20 V and a current value of 2
The discharge was performed until the current decreased to 0 mA, and the discharge was performed at a constant current of 500 mA until the battery voltage reached 3.00V. The discharge capacity retention ratio was calculated as the ratio of the discharge capacity at the 300th cycle to the discharge capacity at the 5th cycle, that is, (discharge capacity at the 300th cycle / 5th discharge capacity) × 100. The results obtained are shown in Table 1. In addition, since the capacity of the positive electrode 21 is the same in all of Examples 1 to 6, the total initial charge capacity in the charging step was almost 600 mAh.

Further, as Comparative Example 1 with respect to Examples 1 to 6, secondary batteries were produced in the same manner as in Examples 1 to 6 except that charging was carried out under normal pressure (atmospheric pressure). Also in Comparative Example 1, the initial discharge capacity and the discharge capacity retention rate were examined in the same manner as in Examples 1 to 6. Table 1 also shows the results.

As can be seen from Table 1, according to Examples 1 to 6 in which pressure is applied during charging, as compared with Comparative Example 1 in which pressure is not applied,
A high discharge capacity retention rate was obtained, and the initial discharge capacity was the same as in Comparative Example 1. In addition, the discharge capacity retention rate increased with increasing pressure, showed a maximum value, and then tended to decrease.

That is, if charging is performed under pressure, the charge / discharge cycle characteristics can be improved while maintaining a high discharge capacity, and the pressure is 1.11 × 10.
^A high effect can be obtained within the range of ⁵ Pa or more and 9.91 × 10 ⁶ Pa or less, and 1.50 × 10 ⁵ Pa or more and 2.06
It has been found that a higher effect can be obtained by setting it within the range of × 10 ⁶ Pa or less.

(Examples 7 to 11) A secondary battery 1 was assembled in the same manner as in Examples 1 to 6 (Fig. 6; step S110).
reference). Next, the secondary battery 1 was initially charged under normal pressure (see FIG. 6; step S130). The charging conditions were the same as the initial charging in Examples 1 to 6 except that uniaxial pressure was not applied. Then, the secondary battery 1 was stored in a pressurized state (see FIG. 6; step S140). At that time, the pressure during storage was 1.08 × 10 ⁶ Pa, and the storage time was from Example 7 to
At 11, the changes were made as shown in Table 2. Thereby, the secondary batteries 1 of Examples 7 to 11 were obtained. Also in Examples 7 to 11, similarly to Examples 1 to 6, the initial discharge capacity and the discharge capacity retention rate were examined. The obtained results are shown in Table 2 together with the results of Comparative Example 1. In addition, also in Examples 7 to 11, the total of the initial charge capacities in the charging step was all about 600 mAh.

[0054]

[Table 2]

As can be seen from Table 2, according to Examples 7 to 11, the initial discharge capacity and the discharge capacity retention rate were
Values equal to or higher than those of Comparative Example 1 could be obtained, and according to Examples 8 to 11, values superior to those of Comparative Example 1 could be obtained for both of them. Moreover, the initial discharge capacity and the discharge capacity retention rate tended to increase with the increase in storage time, reach a maximum value, and then decrease. That is, if the battery is stored under pressure after charging, it is possible to improve the charge / discharge cycle characteristics while keeping the discharge capacity high, and the storage time should be within a range of 1 hour to 500 hours. It was found that a high effect can be obtained, and a higher effect can be obtained within a range of 1 hour to 240 hours.

(Examples 12 to 17) When the secondary battery 1 was stored, the storage time was set to 150 hours, and the pressure was changed as shown in Table 3, except that the storage conditions were changed to those of Examples 7 to 11. A secondary battery 1 was manufactured in the same manner. Regarding the secondary batteries 1 of Examples 12 to 17, the initial discharge capacity and the discharge capacity retention rate were examined in the same manner as in Examples 7 to 11. The obtained results are shown in Table 3 together with the results of Comparative Example 1. In addition, also in Examples 12 to 17, the total of the initial charge capacities in the charging step was all about 600 mAh.

[0057]

[Table 3]

As can be seen from Table 3, according to Examples 12 to 17, similarly to Examples 7 to 11, both the initial discharge capacity and the discharge capacity retention rate were equal to or higher than those in Comparative Example 1. According to Examples 12 to 16, it was possible to obtain values superior to those of Comparative Example 1 for both of them. Further, the initial discharge capacity and the discharge capacity retention rate tended to increase with increasing pressure during storage, reaching a maximum value, and then decreasing. That is, if the battery is stored with a pressure applied after charging, it is possible to improve the charge / discharge cycle characteristics while keeping the discharge capacity high, and the pressure when the secondary battery 1 is stored is 1.11. ×
A high effect can be obtained within the range of 10 ⁵ Pa or more and 9.91 × 10 ⁶ Pa or less, and a higher effect can be achieved within the range of 1.50 × 10 ⁵ Pa or more and 2.06 × 10 ⁶ Pa or less. It turns out that

(Examples 18 to 21) A secondary battery 1 was assembled in the same manner as in Examples 1 to 6 (Fig. 7; step S11).
0). Then, the secondary battery 1 was charged for the first time in a pressurized state in the same manner as in Examples 1 to 6 (FIG. 7; Step S1).
20), and then the secondary battery 1 was stored in a further pressurized state (see FIG. 7; step S140). At that time, the pressure during charging, the time during storage and the pressure were changed as shown in Table 4. Regarding the secondary batteries 1 of Examples 18 to 21, the initial discharge capacity and the discharge capacity retention rate were examined in the same manner as in Examples 1 to 6. The obtained results are shown in Table 4 together with the results of Comparative Example 1. In addition, also in Examples 18 to 21, the total of the initial charge capacities in the charging step was almost 600 mAh.

[0060]

[Table 4]

As can be seen from Table 4, Examples 18-21
According to the above, similarly to Examples 1 to 17, a higher value of the discharge capacity was obtained as compared with Comparative Example 1. Also, the initial discharge capacity was higher than that in Comparative Example 1.

Further, as can be seen by comparing Tables 1 to 3 with Table 4, Examples 18 to 21 are able to obtain much higher initial discharge capacities and discharge capacity maintenance ratios than Examples 1 to 17. did it. That is, if the secondary battery 1 is charged in a pressurized state and then the secondary battery 1 is stored in a pressurized state, a higher effect can be obtained than when either one of the steps is performed. I found out.

Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made. For example, in the above-described embodiments and examples, the secondary battery 1 is charged or stored under pressure, but the pressure may be applied at least temporarily during charging or storage,
Does not need to be done constantly while charging or storing.

In the above embodiment, the pressure is applied during the initial charge or during the storage period after the initial charge. However, the pressure is applied during the charge after the initial charge or during the storage period after the initial charge. Good.

Further, in the above-mentioned embodiment and example,
Although the gel electrolyte layer 23 is formed, a solid organic electrolyte in which an electrolyte salt is dispersed in a polymer compound having ion conductivity, or an electrolyte layer formed of a solid inorganic electrolyte or the like may be used. Such a solid organic electrolyte layer can be obtained by applying a fluid electrolyte layer on the electrode reaction layer and then completely evaporating the non-aqueous solvent.

In addition, although the positive electrode 21 and the negative electrode 22 are wound in the above-described embodiment and examples,
The positive and negative electrodes may be folded or stacked.

Furthermore, in the above-described embodiments and examples, the two exterior members 30a and 30b are adhered to each other and the battery element 20 is enclosed therein. However, one exterior member is bent to form an outer edge portion. May be closely attached and the battery element may be sealed by another method such as sealing.

In addition, in the above-described embodiments and examples, the battery element 20 is enclosed inside the exterior members 30a and 30b made of an aluminum laminate film, but inside the exterior member made of another laminate film. Or a metal container having a cylindrical shape or another shape. In the case of enclosing in a metal container, an electrolyte solution in which an electrolyte salt is dissolved may be used as the electrolyte.

Furthermore, in the above-described embodiments and examples, the secondary battery 1 in which the battery reactive species is lithium has been described, but in the present invention, the battery reactive species is sodium (Na).
Or other alkali metals such as potassium (K), or alkaline earth metals such as magnesium (Mg) or calcium (Ca), or other light metals such as aluminum, or other species such as lithium or alloys thereof. The same can be applied when manufacturing a battery. In that case, sodium salt or potassium salt is used as the electrolyte salt instead of the lithium salt,
Appropriate metal oxide or metal sulfide is used for the positive electrode material.

In addition, in the above-described embodiments and examples, the case of manufacturing the secondary battery has been described, but the present invention can be applied to the case of manufacturing the primary battery.

[0071]

As described above, the method for producing a battery according to any one of claims 1 to 9 or the method for producing a battery according to any one of claims 10 to 16 is effective. For example, because the battery is charged under pressure, or the battery is charged and then stored under pressure, it is possible to prevent the negative electrode from becoming overvoltage. A coating film can be properly formed on the surface of the negative electrode. Therefore, high energy density and high power density can be obtained, and battery characteristics such as charge / discharge cycle characteristics can be improved.

Particularly, according to the battery manufacturing method of any one of claims 7 to 9, after charging the battery under pressure, the battery is stored under pressure. Therefore, a higher effect can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing a method of manufacturing a battery according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a secondary battery disassembled and produced by using the battery manufacturing method according to the first embodiment of the present invention.

3 is a cross-sectional view taken along line I-I of the battery element shown in FIG.

FIG. 4 is a perspective view for explaining a step of pressing a battery.

FIG. 5 is a perspective view for explaining another pressing step of the battery.

FIG. 6 is a flowchart showing a method for manufacturing a battery according to the second embodiment of the present invention.

FIG. 7 is a flowchart showing a method of manufacturing a battery according to the third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Secondary battery, 11 ... Positive electrode lead wire, 12 ... Negative electrode lead wire, 20 ... Battery element, 21 ... Positive electrode, 21a ... Positive electrode collector layer, 21b ... Positive electrode mixture layer, 22 ... Negative electrode, 22a ... Negative electrode collection Electrical layer, 22b ... Negative electrode mixture layer, 23 ... Electrolyte layer, 24 ...
Separator, 25 ... Protective tape, 30a, 30b ... Exterior member, 31 ... Adhesive film, 40 ... Buffer, 41 ... Pressure plate, 50 ... Hydrostatic pressure generating medium

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hidetoshi Ito             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation (72) Inventor Hiroko Onuma             6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni             -Inside the corporation F term (reference) 5H024 AA00 AA02 BB05 BB11 BB18                       DD01 EE09 HH10 HH17                 5H029 AJ03 AJ05 AK02 AK03 AK05                       AK16 AK18 AL02 AL06 AL07                       AL12 AL16 AL18 AM02 AM03                       AM04 AM05 AM07 AM16 CJ03                       CJ16 CJ28 DJ02 DJ16 DJ17                       HJ00 HJ15

Claims (16)

[Claims] 1. A method of manufacturing a battery, comprising: a step of assembling a battery provided with an electrolyte together with a positive electrode and a negative electrode; and a step of charging the assembled battery in a pressurized state. 2. The method for producing a battery according to claim 1, wherein a pressure within a range of 1.11 × 10 ⁵ Pa or more and 9.91 × 10 ⁶ Pa or less is applied during the charging. 3. The method for producing a battery according to claim 1, wherein the battery is assembled using an electrolyte containing a non-aqueous solvent and an electrolyte salt. 4. The method for producing a battery according to claim 1, wherein the battery is assembled using a negative electrode containing a negative electrode material capable of inserting and extracting lithium. 5. The method for producing a battery according to claim 1, wherein the battery is assembled using a positive electrode containing a lithium composite oxide. 6. The method for manufacturing a battery according to claim 1, wherein the step of assembling the battery includes the step of enclosing the positive electrode, the negative electrode, and the electrolyte inside a film-shaped exterior member. 7. The method for manufacturing a battery according to claim 1, further comprising the step of storing the battery in a pressurized state after charging. 8. The method for producing a battery according to claim 7, wherein a pressure within a range of 1.11 × 10 ⁵ Pa or more and 9.91 × 10 ⁶ Pa or less is applied during the storage. 9. The method for producing a battery according to claim 7, wherein the storage under pressure is within a range of 1 hour or more and 500 hours or less. 10. A battery comprising: a step of assembling a battery provided with an electrolyte together with a positive electrode and a negative electrode; a step of charging the assembled battery; and a step of storing the charged battery under pressure. Production method. 11. The method for producing a battery according to claim 10, wherein a pressure within a range of 1.11 × 10 ⁵ Pa or more and 9.91 × 10 ⁶ Pa or less is applied during the storage. 12. The method for producing a battery according to claim 10, wherein the pressure storage is performed within a range of 1 hour or more and 500 hours or less. 13. The battery is assembled using an electrolyte containing a non-aqueous solvent and an electrolyte salt.
A method for manufacturing the battery described above. 14. The method for manufacturing a battery according to claim 10, wherein the battery is assembled using a negative electrode containing a negative electrode material capable of inserting and extracting lithium. 15. The method for manufacturing a battery according to claim 10, wherein the battery is assembled using a positive electrode containing a lithium composite oxide. 16. The step of assembling the battery comprises:
The method for producing a battery according to claim 10, further comprising a step of enclosing the negative electrode and the electrolyte inside a film-shaped exterior member.