JP3306906B2 - Manufacturing method of non-aqueous electrolyte secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery using a carbonaceous material, lithium, or a lithium alloy as a negative electrode active material. The present invention relates to a method for producing a non-aqueous electrolyte secondary battery characterized by having

[0002]

2. Description of the Related Art In recent years, with the spread of portable devices such as video cameras and boomboxes, demand for secondary batteries that can be used repeatedly instead of disposable primary batteries has been increasing.

Most of the secondary batteries currently used are nickel cadmium batteries using an alkaline electrolyte. However, since the voltage of this battery is about 1.2 V, it is difficult to improve the battery energy density. Another drawback is that the self-discharge rate at room temperature is as high as 20% or more in one month.

[0004] Therefore, a non-aqueous electrolyte secondary battery using a non-aqueous solvent for the electrolyte and a light metal such as lithium for the negative electrode has been studied. This non-aqueous electrolyte secondary battery has a high energy density of 3 V or more and a low self-discharge rate. However, such a non-aqueous electrolyte secondary battery is disadvantageous in that metal lithium or the like for the negative electrode grows in a dendrite shape by repeated charge and discharge and comes into contact with the positive electrode, and as a result, a short circuit easily occurs inside the battery. However, practical application is also difficult.

For this reason, a non-aqueous electrolyte secondary battery in which lithium or the like is alloyed with another metal and this alloy is used for a negative electrode has been studied. However, in this case, practical use is also difficult because of the drawback that the alloy is liable to become particles due to repeated charging and discharging.

Accordingly, for example, Japanese Patent Application Laid-Open No. 62-90863
As disclosed in Japanese Unexamined Patent Publication, a non-aqueous electrolyte secondary battery using a carbonaceous material such as coke as a negative electrode active material has been proposed. Since this nonaqueous electrolyte secondary battery does not have the above-described disadvantages of the negative electrode, it has excellent cycle life characteristics. As the positive electrode active material, Li _X MO ₂ (M represents one or more transition metals, as proposed by the present inventors in Japanese Patent Application No. 63-135099, and 0.05 <x <1.10), the battery capacity is improved, and a non-aqueous electrolyte secondary battery with high energy density can be obtained.

[0007]

By the way, a non-aqueous electrolyte secondary battery uses a carbonaceous material, lithium,
Since a lithium alloy is used, the discharge capacity is extremely high, that is, two to three times that of a conventional battery, and the effect of a voltage failure is serious. For this reason, when shipping, it is necessary to eliminate in advance without fail any defective batteries that may cause voltage failure when used at the specified maximum charging voltage, and supply only highly reliable products to users. is there.

Therefore, the present invention has been proposed in view of such a conventional situation, and a defective voltage is not leaked.
It is another object of the present invention to provide a method for manufacturing a non-aqueous electrolyte secondary battery that can be efficiently removed and supply only a highly reliable product to a user.

[0009]

In order to achieve the above object, the present invention relates to a method for manufacturing a non-aqueous electrolyte secondary battery comprising a negative electrode, a positive electrode, and a non-aqueous electrolyte. provisions charging maximum voltage when the _{V M, V M} ≦ _V
Was charged with final voltage V _C which satisfies the _C ≦ V _{M +} 0.15V the relationship, is characterized in that selecting a good or bad of the battery from径時change of battery voltage in the subsequent in standing.

[0010] The method of manufacturing a non-aqueous electrolyte secondary battery according to the present invention is a method of manufacturing a non-aqueous electrolyte secondary battery including a negative electrode, a positive electrode, and a non-aqueous electrolyte. _M , then V _M +0.05 V ≦ V _C ≦ V
Was charged with final voltage V _C which satisfies the _{M +} 0.15V the relationship, is characterized in that selecting a good or bad of the battery from径時change of battery voltage in the subsequent in standing.

Further, the method for producing a non-aqueous electrolyte secondary battery of the present invention is characterized in that a material capable of doping and undoping lithium is used for the positive electrode and the negative electrode. The manufacturing method of the water electrolyte secondary battery uses a carbon material capable of doping / dedoping lithium as a negative electrode and Li _X MO2 (where M is C
O, Ni, Mn, or one or more selected from Fe, and 0.05 < _X <1.10.

[0012] Non-manufacturing method of aqueous electrolyte secondary battery of the present invention, since the voltage failure advance eliminated before shipping products with a possibility to occur when used in defining maximum charging voltage V _M, after assembly of the _{battery, V M ≦ V C ≦ V} M +0.15
It was charged with final voltage V _C which satisfies the V the relationship, then left good battery from aging of the battery voltage during evaluates the failure, to ship only as a product that is evaluated as valid.

Here, for example, the final voltage V _{C at} the time of charging
To the case of a less than V _M is, too charging condition is relaxed, it is not possible to completely eliminate the voltage defective products. On the other hand, if the cut-off voltage V _C is set to exceed V _M +0.15 V, the charging conditions are too severe, causing a failure in the battery (probably due to the deposition of lithium on the negative electrode). In the maximum charging voltage range, there is a possibility that even a case where no problem occurs is excluded. Accordingly, the present invention is set to the range end voltage V _C during the charge. Note that to more reliably eliminate the voltage defective, the final voltage _{V C} is _{V M + 0.05V ≦ V C ≦} V M +
It is preferable to set so as to satisfy the relationship of 0.15V.

As the negative electrode active material used in the present invention, a carbonaceous material, lithium, and a lithium alloy are used. As the carbonaceous material, a material capable of doping and undoping lithium is used. Decomposed carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, glassy carbons, fired bodies of organic polymer compounds (phenol resins, furan resins, etc. fired at appropriate temperatures), Carbon fiber, activated carbon and the like can be used.

As the lithium alloy, Li-Al, Li
Alloys such as -Sn and Li-Pb;

As the electrolytic solution, any conventionally known one can be used as long as the electrolyte is dissolved in an organic solvent. Accordingly, examples of the organic solvent include esters such as propylene carbonate, ethylene carbonate, and γ-butyrolactone, ethers such as diethyl ether, tetrahydrofuran, substituted tetrahydrofuran, dioxolan, pyran and derivatives thereof, dimethoxyethane, and diethoxyethane; 3-substituted-2-oxazolidinones such as -methyl-2-oxazolidinone, sulfolane,
Methyl sulfolane, acetonitrile, propionitrile and the like can be mentioned, and these are used alone or in combination of two or more. Further, as the electrolyte, lithium perchlorate, lithium borofluoride, lithium phosphofluoride, lithium aluminate, lithium halide, lithium trifluoromethanesulfonate and the like can be used.

[0017]

[Action] In defining maximum charging voltage is V _M non-aqueous electrolyte secondary battery, after assembly of the battery, V _M ≦ V _C ≦ V _M +
Was charged with final voltage V _C which satisfies the 0.15V the relationship, then good battery from aging of the battery voltage during the standing, to evaluate the failure and to ship only as a product that is evaluated as valid, defined charge Voltage failure does not occur within the maximum voltage range, and only highly reliable products are supplied to users.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on specific experimental results. Embodiment 1 FIG. 1 shows a nonaqueous electrolyte secondary battery of this embodiment.

This non-aqueous electrolyte secondary battery was prepared as follows.

First, the positive electrode plate 1 was manufactured as follows.

One mole of lithium carbonate and one mole of cobalt carbonate were mixed and calcined in air at 900 ° C. for 5 hours to obtain LiCoO ₂ . This LiCoO ₂ was pulverized with a bowl mill to obtain a positive electrode compound powder. 91 parts by weight of the positive electrode compound powder, 6 parts by weight of graphite as a conductive agent, and 3 parts by weight of polyvinylidene fluoride as a binder were mixed, and N-methylpyrrolidone was added as a dispersant to prepare a positive electrode mixture paste. Was. Then, the positive electrode mixture paste is uniformly applied to both sides of a 30 μm-thick aluminum foil current collector and dried,
The positive electrode plate 1 was obtained by performing a roller press.
The positive electrode plate 1 has a width of 35 mm, a length of 300 mm,
It was a plate having a thickness of 0.18 mm. An aluminum lead wire 7 was attached to an end of the positive electrode plate 1 by welding.

The negative electrode plate 2 was manufactured as follows.

The negative electrode active material was prepared by mixing pitch coke in a vibrating mill together with stainless steel balls having a diameter of 12.7 mm.
Obtained by milling for minutes. The true density of this pitch coke is 2.03 g / cm ³ , the (002) plane spacing determined by X-ray diffraction measurement according to the Japan Society for the Promotion of Science is 3.64 °, and the crystal thickness Lc in the C-axis direction is 40 °. Met. Next, 90 parts by weight of the granular pitch coke and 10 parts by weight of polyvinylidene fluoride as a binder were mixed, and N-methylpyrrolidone was added as a dispersant to prepare a negative electrode mixture paste. Then, as shown in FIG. 2, the negative electrode mixture paste is uniformly applied to both surfaces of a copper foil current collector 5 having a thickness of 10 μm to form active material layers 6a and 6b.
Was formed and dried, and then a roller press was performed to obtain a negative electrode plate 2. The negative electrode plate 2 has a width 3
It was a plate having a size of 5 mm, a length of 300 mm, and a thickness of 0.2 mm. A nickel lead wire (not shown) was attached to an end of the negative electrode plate 2 by welding.

Using the positive electrode plate 1, the negative electrode plate 2, and a pair of thin plate separators 3a and 3b made of polypropylene, the negative electrode plate 2, the separator 3a, the positive electrode plate 1, and the separator 3b are laminated in this order. These were spirally wound. The wound body was housed in a nickel-plated iron battery can 4. In this case, the above-mentioned lead wire was welded to the battery can 4 and the battery lid 9. As the electrolytic solution, a mixed solution of propylene carbonate in which lithium hexafluorophosphate was dissolved at 1 mol / l and diethyl carbonate was used. Then, after injecting this mixed solution into the battery can 4, the polypropylene gasket 8 and the battery lid 9 are attached to the battery can 4
The battery is sealed by inserting the battery can 4 into the upper portion and crimping the upper portion of the battery can 4, as shown in FIG.
800 cells of a cylindrical unestimated battery having a size of 8 mm and a height of 45 mm were produced. The specified maximum charging voltage (recommended voltage) of this battery is 4.1 V.

Primary evaluation was performed on 100 of the above-not-evaluated batteries to select non-defective products, and the products selected as non-defective products were examined for the presence of defective voltage.

First, in order to perform a primary evaluation, the charging current 10
Constant current and constant voltage charging was performed under the conditions of 0 mA and a final voltage of 4.10 V, and the voltage was measured. And then at room temperature 28
It was left for a day and the voltage was measured again. At this time, the voltage is 4.0
Batteries having a voltage lower than 0 V were evaluated as defective voltage products (primary defective products), and the number of batteries was examined.

Next, all the batteries evaluated as non-defective products (batteries that did not cause a voltage defect) were charged at a charge current of 100 mA, with a cut-off voltage of 4.1 V, which is the recommended voltage of the battery, and a discharge current of 100 mA. 100 mA, end voltage 2.
Charge / discharge, such as performing constant current discharge under the condition of 5V, is 100
Repeated times. Then, after charging at 4.10 V, the voltage of the battery stored for 28 days is measured, and a battery having a voltage lower than 4.00 V is a defective battery (secondary defective).
And the number was examined.

Table 1 shows the numbers of primary defective products and secondary defective products. Examples 2 to 6 An unevaluated battery was manufactured in the same manner as in Example 1. And
With respect to this unevaluated battery, the number of primary defectives and secondary defectives was examined in the same manner as in Example 1 except that the end-of-charge voltage for selecting the primary defectives was set as shown in Table 1. The results are shown in Table 1. Comparative Examples 1 to 3 An unevaluated battery was produced in the same manner as in Example 1. And
With respect to this unevaluated battery, the number of primary defectives and secondary defectives was examined in the same manner as in Example 1 except that the end-of-charge voltage for selecting the primary defectives was set as shown in Table 1. The results are shown in Table 1.

[0029]

[Table 1]

As can be seen from Table 1, in Examples 1 to 6, the number of secondary defective products is small, and it can be seen that defective products are surely excluded by the primary evaluation. On the other hand, in Comparative Example 1 and Comparative Example 2, the number of secondary defective products was large, and defective products were not completely eliminated during the primary evaluation. In Comparative Example 3, even batteries that do not cause any problem at the specified maximum charging voltage are excluded by the primary evaluation, and the product supply rate is reduced.

[0031] Therefore, from this fact, in a non-aqueous electrolyte secondary battery defined maximum charging voltage is V _M, V _M
≦ V _C ≦ V _{M +} 0.15V made to satisfy the relationship end voltage V _C at good performing charging, determining defective effective in efficiently supplying the non-aqueous electrolyte secondary battery having high reliability I found it.

In this embodiment, a carbonaceous material is used as the negative electrode active material, but it is a matter of course that other materials may be used. In addition, as the positive electrode active material, Li _x MO ₂ (M is one or more transition metals) as described above can be used.

The shape of the battery may be rectangular, coin-shaped, button-shaped or the like in addition to the cylindrical shape in the present embodiment. The non-aqueous electrolyte may be a solid, and in this case, a conventionally known solid electrolyte can be used.

[0034]

As is clear from the above description, the present invention, after assembly of the battery, the provision charge maximum voltage of the battery V _M
And when, was charged with _{V M ≦ V C ≦ V M} + 0.15V made to satisfy the relationship end voltage V _C, good battery from aging of the battery voltage in a subsequent in standing, so to assess the defect, defined Products that may cause voltage failure when used within the maximum charging voltage range can be eliminated without omission, and only good products can be shipped efficiently. Therefore,
According to the present invention, it is possible to provide a user with a highly reliable non-aqueous electrolyte secondary battery.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example of a non-aqueous electrolyte secondary battery to which the present invention is applied, partially cut away.

FIG. 2 is a schematic perspective view of a main part showing a state in which a negative electrode plate is partially cut away.

[Explanation of symbols]

 1 ... Positive electrode plate 2 ... Negative electrode plate 3a, 3b ... Separator 4 ... Battery can 7 ... Positive electrode lead 8 ... ..... Gasket 9 ... Battery cover

Claims (4)

(57) [Claims] 1. A non-aqueous electrolyte comprising a negative electrode, a positive electrode, and a non-aqueous electrolyte.
In the method of solution electrolyte secondary battery, the after battery assembly defining maximum charging voltage when the V _M, V _M
In ≦ _{V C} ≦ _{V M} + 0.15V made to satisfy the relationship end voltage _{V C}
Changes in battery voltage over time during charging and after standing
Non-aqueous battery characterized by selecting good or bad battery
Manufacturing method of degraded secondary batteries. 2. A non-aqueous electrolyte comprising a negative electrode, a positive electrode, and a non-aqueous electrolyte.
In the method of solution electrolyte secondary battery, the after battery assembly defining maximum charging voltage when the V _M, V _M
Satisfy _{+ 0.05 ≦ V C ≦ V M} + 0.15V the relationship
Was charged at the stop voltage V _C, the battery in a subsequent in standing
How to distinguish good / bad batteries from changes in voltage
A method for producing a non-aqueous electrolyte secondary battery, characterized by: 3. Doping and dedoping lithium into a positive electrode and a negative electrode
2. The non-volatile memory device according to claim 1, wherein
A method for producing a water electrolyte secondary battery. 4. Doping and undoping of lithium as a negative electrode
Li _X MO2 as the positive electrode active material using the obtained carbon material
(However, M is one selected from CO, Ni, Mn, and Fe
Or at least one kind, and 0.05 < _X <1.10.
2. The non-aqueous electrolyte according to claim 1, wherein
A method for manufacturing a secondary battery.