JPH09245773A - Manufacture of electrode for non-aqueous solvent secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode for non-aqueous solvent secondary battery capable of avoiding curing of slurry containing fluoro-vinylidene type fluoro- rubber as a bonding agent under the existence of alkaline components. SOLUTION: This electrode for non-aqueous solvent secondary battery consists of a process for preparing a compound oxide with at least one metal and lithium to be selected from among cobalt, nickel, and manganese as an active substance, preparing a slurry containing a fluoro-vinylidene type fluoro-rubber and an organic solvent as a binder, and process for applying the above slurry to an electric collector or filling. In this case, the above slurry is prepared by agitating it while an electrode material containing the above bonding agent and above organic solvent is maintained to below 20 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrode for a non-aqueous solvent secondary battery.

[0002]

2. Description of the Related Art Recent advances in electronic technology have reduced power consumption,
2. Description of the Related Art Advances in packaging technology have led to smaller and more portable electronic devices that could not be predicted in the past. with this,
There is a demand for higher capacity secondary batteries which are power supplies for these electronic devices. As such a secondary battery, a non-aqueous solvent secondary battery using lithium as a negative electrode active material and combining a positive electrode containing LiCoO ₂ , a negative electrode containing a carbonaceous material, and a non-aqueous electrolyte has been developed and is currently used in large quantities. ing.

However, LiCoO ₂ is expensive because it contains cobalt, and is limited in resources. Therefore, LiNiO _{2 is} used as an alternative material, or LiNi _{1− in} which nickel is partially substituted with cobalt. _X Co _x O
₂ or a metal oxide-based compound such as LiMn ₂ O ₄ has been proposed and is being actively researched.

As a method for producing an electrode containing a lithium composite oxide as described above, the composite oxide is added to a solution in which a binder is dispersed in an organic solvent, and these materials are stirred at room temperature. A slurry is prepared by circulating water so as not to be deteriorated by frictional heat, and stirring while maintaining the temperature at about 30 to 40 ° C., applying the slurry on a current collector, drying and rolling. A method of forming a thin plate is adopted. Examples of the binder include polytetrafluoroethylene (PTF)
E), polyvinylidene fluoride (PVdF), ethylene-
Propylene-diene copolymer (EPDM), styrene
Butadiene rubber (SBR) is used. Among them,
Polyvinylidene fluoride is one of the preferred materials as a binder for the electrode because it has excellent resistance to dissolution in a non-aqueous electrolyte and high adhesion to a current collector.

However, since polyvinylidene fluoride has low alkali resistance, if an unreacted lithium salt remains in the composite oxide, the slurry hardens in a relatively short time after preparation, and becomes a current collector. There is a problem that it becomes difficult to apply. Therefore, it is necessary to immediately apply and dry the slurry before the slurry is hardened, which has been a great obstacle to mass productivity.

For this reason, when LiCoO ₂ was used as the lithium composite oxide, water washing was carried out to remove the lithium salt remaining in the composite oxide. It was difficult to completely remove it, and it was difficult to avoid hardening of the slurry.

On the other hand, nickel-based oxides such as LiNiO ₂ are more unstable with respect to water than LiCoO ₂ , and thus, when washed with water to remove unreacted lithium salts, the charge / discharge characteristics deteriorate. There is a problem.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to leave unreacted lithium salt in a lithium composite oxide as an active material, that is, vinylidene fluoride-based fluorine as a binder in the presence of an alkali component. An object of the present invention is to provide a method for manufacturing an electrode for a non-aqueous solvent secondary battery, which can avoid curing of a slurry containing rubber.

[0009]

According to a first aspect of the present invention, there is provided a method for producing an electrode for a non-aqueous solvent secondary battery, comprising the step of forming a composite of lithium and at least one metal selected from cobalt, nickel and manganese as an active material. An electrode for a non-aqueous solvent secondary battery, comprising: a step of preparing a slurry containing an oxide and a vinylidene fluoride-based fluororubber as a binder and an organic solvent; and a step of applying or filling the slurry on a current collector. Wherein the slurry is prepared by stirring the electrode material containing at least the active material, the binder and the organic solvent at a temperature of 20 ° C. or less.

Further, the second method for producing an electrode for a non-aqueous solvent secondary battery according to the present invention provides a method of producing a composite oxide of lithium and at least one metal selected from cobalt, nickel and manganese as an active material. A step of preparing a slurry containing vinylidene fluoride-based fluororubber and an organic solvent as a binder, a step of storing the slurry at 20 ° C. or lower, and a step of applying or filling the slurry on a current collector It is characterized by the following.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following are specific examples of the first method for producing an electrode for a non-aqueous solvent secondary battery according to the present invention (1) to (1).
The two methods shown in (2) will be described. (1) A composite oxide of lithium and at least one metal selected from cobalt, nickel, and manganese as an active material, vinylidene fluoride-based fluororubber as a binder, and a conductive agent as necessary are added to an organic solvent. , This 2
The active material and the binder (and the conductive agent) are dispersed in the organic solvent by stirring while being kept at 0 ° C. or lower, and the slurry is prepared. Then, the slurry is applied to a current collector or The electrode for a non-aqueous solvent secondary battery is manufactured by filling, drying and, if necessary, rolling. <Slurry preparation step> Examples of the composite oxide include LiCoO ₂ , LiNiO ₂ , and LiNi _1-x Co _x.
O ₂ and LiMn ₂ O ₄ can be exemplified.

The composite oxide is allowed to contain unreacted substances such as lithium salts and impurities. Examples of the vinylidene fluoride-based fluororubber as the binder include a polyvinylidene fluoride represented by the following chemical formula 1, a copolymer of vinylidene fluoride-6-propylene fluoride represented by the following chemical formula 2, and a chemical formula represented by the following chemical formula 3.
Vinylidene fluoride-tetrafluoroethylene-6 shown in
A terpolymer of propylene fluoride, a copolymer of vinylidene fluoride-pentafluoropropylene shown in Chemical Formula 4 below,
Examples thereof include a vinylidene fluoride-chlorotrifluoroethylene copolymer represented by the following formula 5, or a copolymer obtained by copolymerizing another fluorine-based monomer with vinylidene fluoride. Examples of the copolymerization of such another fluorine-based monomer with vinylidene fluoride include tetrafluoroethylene-
Copolymer of vinylidene fluoride, terpolymer of tetrafluoroethylene-perfluoroalkylvinyl ether (PFA) -vinylidene fluoride, terpolymer of tetrafluoroethylene-hexafluoropropylene (FEP) -vinylidene fluoride Copolymer of tetrafluoroethylene-ethylene-vinylidene fluoride, copolymer of chlorotrifluoroethylene-vinylidene fluoride, terpolymer of chlorotrifluoroethylene-ethylene-vinylidene fluoride, vinyl fluoride-fluoride And copolymers of vinylidene fluoride. These binders may be used alone or in combination of two or more.

[0013]

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[0014]

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[0015]

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[0016]

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[0017]

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Examples of the conductive agent include acetylene black, graphite, carbon black and the like. Examples of the organic solvent include N-methylpyrrolidone (NMP), dimethylformamide (D
MF) or the like is used.

The amount of the active material is from 80% by weight to 100 parts by weight of the active material and the binder in total (or 100 parts by weight of the conductive agent when the conductive material is included). It is preferred to be in the range of 98% by weight.

The blending amount of the binder is 2% by weight based on 100 parts by weight of the active material and the binder in total (or 100 parts by weight of the conductive agent when the conductive agent is included).
It is preferable to set it in the range of 20 to 20% by weight.

The amount of the conductive agent is 0 to 100 parts by weight of the total of the active material, the binder and the conductive agent.
It is preferable that the content be in the range of 18% by weight to 18% by weight. The blending amount of the organic solvent is 65 wt% to 150 wt% with respect to 100 parts by weight of the active material and the binder (100 parts by weight of the conductive agent when the conductive agent is included). It is preferable that it is within the range.

The active material, the binder, the conductive agent and the organic solvent may be blended in the slurry in the above-mentioned blending amounts. However, under certain production conditions, the curing rate of the slurry in the presence of an alkali is considered. Since it tends to vary depending on the mixing ratio between the active material and the binder or the ratio between the solid content and the solvent, it is more preferable that the mixing ratio be such that the curing can be suppressed. For example, when preparing a slurry containing LiNiO ₂ as an active material, setting the weight ratio of the binder to the active material to 5.5 × 10 ⁻² or more can significantly suppress the curing of the slurry. Therefore, it is preferable to mix electrode materials such as an active material, a binder, and an organic solvent so as to satisfy such a weight ratio. However, if the weight ratio exceeds 0.25, the amount of active material contained in the electrode may decrease, and the energy density may decrease. Therefore, the upper limit of the weight ratio is preferably set to 0.25.

The reason why the electrode material containing at least the active material, the binder and the organic solvent is kept at a temperature within the above-mentioned range when the materials are stirred and mixed is as follows. If the temperature at the time of stirring and mixing exceeds 20 ° C., it becomes difficult to suppress or avoid hardening of the slurry.
In order to prolong the pot life of the slurry and improve the adhesion between the slurry and the current collector, the temperature during stirring and mixing is preferably 10 ° C. or less. The lower the temperature during stirring and mixing, the better. However, if the temperature is too low, the organic solvent may coagulate. Therefore, it is preferable to set the temperature during stirring and mixing to a temperature equal to or higher than the coagulation point of the organic solvent. For example, when N-methylpyrrolidone is used as the organic solvent, the temperature during stirring and mixing is preferably set to at least -22.97 ° C.

As a means for stirring and mixing the electrode materials, a ball mill, a bead mill, a dissolver, a sand grinder and the like can be employed. As a method of controlling the temperature of the electrode material, local cooling using a heat exchanger, cooling by air conditioning, attaching a cooling pipe to a container containing the electrode material, and circulating cooling water through the cooling pipe Cooling etc. can be mentioned. Above all, it is preferable to employ cooling with cooling water from the viewpoint of mass productivity, mass production cost, ease of maintenance, and the like. <Slurry coating step> Examples of the current collector to which the prepared slurry is coated or filled include aluminum foil, stainless steel foil, titanium foil and the like.

When the slurry is applied or filled on the current collector, the slurry is preferably kept at a temperature of 20 ° C. or less. If the temperature of the slurry exceeds 20 ° C., the curing of the slurry may proceed during coating. In order to improve the adhesion between the slurry and the current collector, the temperature of the slurry is preferably maintained at 10 ° C. or lower.
The lower the temperature of the slurry, the better. However, if the temperature is too low, the organic solvent in the slurry may coagulate. Therefore, it is preferable to set the temperature of the slurry to a temperature above the coagulation point of the organic solvent.

Means for applying the slurry include:
A comma coater, lip coater, die coater or the like can be employed. When the slurry is kept at a temperature of 20 ° C. or lower, a cooling mechanism may be provided in the slurry reservoir of each coater.

Hereinafter, the manufacturing method (2) will be described. (2) A composite oxide of lithium and at least one metal selected from cobalt, nickel, and manganese as an active material, vinylidene fluoride-based fluororubber as a binder, and a conductive agent as needed are added to an organic solvent. , This 2
The active material and the binder (and the conductive agent) are dispersed in the organic solvent by stirring while maintaining the temperature at 0 ° C. or lower, and the slurry is prepared. The slurry is stored at 20 ° C. or lower. The above-mentioned slurry is applied to or filled in a current collector, dried, and rolled, if necessary, to produce an electrode for a non-aqueous solvent secondary battery.

As the active material, the binder, the conductive agent, the organic solvent, and the current collector, the same materials as described above can be used. <Slurry preparation step> This slurry preparation step is performed by a method similar to that described in the above-mentioned production method (1). <Slurry Storage Step> The prepared slurry is stored at the temperature within the above range for the following reason.
If the temperature of the slurry during storage exceeds 20 ° C., it becomes difficult to suppress or avoid hardening of the slurry. In order to extend the pot life of the slurry and improve the adhesion between the slurry and the current collector, the slurry temperature during storage should be 1
The temperature is preferably set to 0 ° C or lower. The lower the temperature of the slurry, the better. However, if the temperature is too low, the organic solvent in the slurry may be solidified. Therefore, the storage temperature of the slurry is preferably set to a temperature equal to or higher than the freezing point of the organic solvent. <Slurry coating step> This slurry coating step is performed by the same method as described in the manufacturing method (1) above.

Hereinafter, the method (3) which is a specific example of the method for producing the second nonaqueous solvent secondary battery electrode according to the present invention will be described. (3) A composite oxide of lithium and at least one metal selected from cobalt, nickel and manganese as an active material, a vinylidene fluoride-based fluororubber as a binder and a conductive agent as required are added to an organic solvent. The active material and the binder (and the conductive agent) are dispersed in the organic solvent by stirring while cooling so that the slurry is not deteriorated by frictional heat due to the stirring, and the slurry is prepared. The slurry is stored at a temperature of 20 ° C. or lower, and the slurry is applied or filled on a current collector, dried, and rolled as necessary to produce an electrode for a non-aqueous solvent secondary battery.

As the active material, the binder, the conductive agent, the organic solvent, and the current collector, the same materials as described above can be used. <Slurry preparation step> The temperature during stirring is, for example, 20 ° C.
It is preferable to set the temperature in the range of ５０50 ° C.

As the stirring and mixing means, the same means as described above can be used. As the temperature control method at the time of stirring and mixing, the same method as described above can be adopted. <Slurry Storage Step> This slurry storage step is performed by the same method as described in the manufacturing method (1) above. <Slurry coating step> This slurry coating step is performed by the same method as described in the manufacturing method (1) above.

As a result of intensive studies, the present inventors have found that a composite oxide of lithium and at least one metal selected from cobalt, nickel and manganese as an active material, a vinylidene fluoride-based fluororubber as a binder and It has been found that there is a correlation between the curing rate after preparing a slurry containing an organic solvent and the temperature of the slurry.

That is, it is considered that the hardening of the slurry occurs because the unreacted lithium salt contained in the composite oxide causes a crosslinking reaction of the vinylidene fluoride-based fluororubber. As in the conventional method, at room temperature,
The electrode material containing the composite oxide in which the unreacted lithium salt remains, the vinylidene fluoride-based fluororubber, and the organic solvent is cooled so as not to be excessively heated by frictional heat caused by stirring, and stirred while being kept at 30 to 40 ° C. After the slurry is prepared, the resulting slurry is allowed to stand at room temperature, gelation starts in about 2 hours, and is completely cured in about 12 hours, making it impossible to apply to the current collector. . From this, it is expected that the activation energy of the crosslinking reaction is small. From a kinetic point of view,
If the temperature is higher, the vinylidene fluoride-based fluororubber swells, which increases the reaction area and the reaction rate, and is considered to promote the crosslinking reaction. Actually, after a slurry was prepared according to a conventional method and heated to 60 ° C., hardening was recognized in a few minutes.

From the above, it has been found that the curing speed of the slurry in the presence of the alkali component becomes faster as the temperature rises. Further, as a result of further research, whether the temperature at the time of slurry preparation is 20 ° C. or lower as in the present invention,
Alternatively, it has been found that when the prepared slurry is stored at 20 ° C. or lower, the hardening of the slurry after preparation can be suppressed or avoided.

Accordingly, the method for producing an electrode for a non-aqueous solvent secondary battery according to the present invention, that is, stirring the electrode material containing at least the active material, the binder and the organic solvent at a temperature of 20 ° C. or less. By providing the step of preparing the slurry, it is possible to suppress or avoid hardening of the slurry after the preparation, so that the usable time of the slurry can be extended, and mass productivity can be improved. . Moreover, since the slurry prepared by such a method can improve the adhesion to the current collector, the falling of the active material in the electrode can be suppressed or avoided. Furthermore, the treatment for removing the unreacted lithium salt in the active material is not required, which not only enables mass production of an electrode containing a nickel-based composite oxide such as LiNiO ₂ as an active material, but also enables the strength of the electrode to be improved. Can be greatly improved.

Further, another method for producing an electrode for a non-aqueous solvent secondary battery according to the present invention comprises a step of preparing a slurry containing the active material, the vinylidene fluoride-based fluororubber, and the organic solvent; And a step of coating or filling the current collector with the slurry. According to such a method, a large amount of slurry can be prepared and stored for a long time without being cured, so that mass productivity can be greatly improved. In addition, the slurry stored in this way can enhance the adhesion to the current collector, and thus can prevent or prevent the active material from falling off from the electrode. Further, it is not necessary to remove the lithium salt remaining in the active material, which not only enables mass production of an electrode containing a nickel-based composite oxide such as LiNiO ₂ as an active material, but also greatly increases the strength of the electrode. Can be improved.

Further, by keeping the temperature of the slurry at 20 ° C. or less during both the preparation and storage of the slurry, the slurry can be prevented from hardening before coating, so that the mass productivity is dramatically improved. Can be improved. At the same time, the adhesiveness of the slurry to the current collector can be greatly increased, so that the electrode characteristics can be significantly improved.

[0038]

Embodiments of the present invention will be described below in detail. Examples 1-5 Nickel hydroxide {Ni (OH) ₂ } and lithium hydroxide 1
A hydrate (LiOH.H ₂ O) was mixed at a molar ratio of Li to Ni of 1: 1 and heat-treated at a temperature of 70 ° C. for 5 hours in an oxygen stream to obtain a LiNiO ₂ powder. . Note that washing with water for removing the alkaline component in the obtained LiNiO ₂ powder was not performed.

The LiNiO ₂ powder and acetylene black were added to a solution of polyvinylidene fluoride dissolved in N-methylpyrrolidone, and the resulting suspension was stirred with a dissolver while maintaining the temperature shown in Table 1 below. Then, three kinds of slurries containing 90% by weight of LiNiO ₂ , 5% by weight of acetylene black and 5% by weight of polyvinylidene fluoride were prepared by mixing. The temperature control during preparation was performed by circulating cooling water through a cooling pipe attached to the outer wall of the container. When the temperature of the cooling water is 0 ° C., 10 ° C., 20 ° C., the temperature of the slurry is 0 ° C., 10 ° C.
° C and 20 ° C, respectively.

Of the obtained slurries, those prepared at 10 ° C. and those prepared at 20 ° C. were each bisected to obtain five types of slurries. Each of the slurries was controlled at a constant temperature controlled at the temperature shown in Table 1 below. It was left in the tank. Example 6 A LiNiO ₂ powder was obtained in the same manner as in Examples 1 to 5. The above-mentioned LiNiO ₂ powder and acetylene black were stirred with a dissolver and mixed with a solution in which polyvinylidene fluoride was dissolved in N-methylpyrrolidone. On this occasion,
The temperature of the mixture in the container during the stirring was maintained at 41 ° C. by circulating tap water through a cooling pipe provided on the outer wall of the container. By the stirring, a slurry containing 90% by weight of LiNiO ₂ , 5% by weight of acetylene black and 5% by weight of polyvinylidene fluoride was prepared.

The obtained slurry was left in a thermostat controlled at a temperature shown in Table 1 below. Comparative Examples 1 and 2 Example 1 was repeated except that tap water was circulated through a cooling pipe attached to the outer wall of the container, and the slurry was prepared by stirring while keeping the electrode material in the container at 47.8 ° C.
A slurry was prepared in the same manner as in No. 5 to No. 5.

The obtained slurry was divided into two parts, and each slurry was left in a thermostat controlled at a temperature shown in Table 1 below.
The viscosity change of the slurries of Examples 1 to 6 and Comparative Examples 1 and 2 that were left was measured using a B-type viscometer, and the results were shown in FIG.
Shown in The rotor of the B-type viscometer was No. 5 was used.

[0043]

[Table 1]

As is clear from FIG. 1, when the slurry was prepared, Examples 1 to 5 which were kept at 20 ° C. or less were compared with Comparative Examples 1 and 2 in which such a temperature control was not performed, and when the slurry was left. It can be seen that the increase in viscosity can be suppressed. In particular, it can be seen that in Examples 1 to 3 stored at 10 ° C or lower after preparation, the viscosity is almost constant over a long period of time.

In addition, the temperature control is not performed during dispersion,
In Example 6, which was stored at 10 ° C after the preparation of the slurry, the viscosity was almost constant over a long period of time as in Examples 1 to 3,
It can be seen that hardening of the slurry can be avoided by storing the prepared slurry at 20 ° C. or lower.

Therefore, from the above Examples 1 to 6, the slurry temperature during preparation was maintained at 20 ° C. or lower as in the present invention, or the prepared slurry was stored at 20 ° C. or lower. It was confirmed that by performing the temperature control during both storage and storage, the curing of the slurry before coating can be suppressed even in the presence of an alkali component.
Examples 7 to 8 LiNiO ₂ powder was obtained in the same manner as in Examples 1 to 5. The LiNiO ₂ powder and acetylene black were added to a solution of polyvinylidene fluoride dissolved in N-methylpyrrolidone, and the resulting suspension was stirred with a dissolver while maintaining the temperature shown in Table 2 below, followed by mixing. Thereby, two types of slurries containing 90% by weight of LiNiO ₂ , 5% by weight of acetylene black and 5% by weight of polyvinylidene fluoride were prepared. The temperature control during preparation was performed in the same manner as in Examples 1 to 5. The obtained slurry was immediately applied to one surface of an aluminum substrate, dried, and then rolled with a roller press to produce an electrode for a non-aqueous solvent secondary battery. Comparative Example 3 Examples 7 to 8 except that tap water was circulated through a cooling pipe attached to the outer wall of the container and the slurry was prepared by stirring the electrode material in the container while maintaining the temperature at 39 ° C.
In the same manner as in the above, an electrode for a non-aqueous solvent secondary battery was manufactured.

The obtained electrodes of Examples 7 to 8 and Comparative Example 3 were sized to have a width of 1.5 cm and a length of 5 cm in order to examine the peel strength.
Cut out to size. The coated surface of the obtained electrode piece and the glass plate were adhered with a double-sided tape to prepare a test piece.
This test piece was set on a rheometer (trade name: NRM-2010 · CW, manufactured by Fudo Kogyo Co., Ltd.), and 2c from a direction of 170 to 180 degrees with respect to the longitudinal direction of the electrode piece.
Peeling was performed at a constant speed of m / min. At this time, the force applied to the electrode piece was measured, and the value at which the force was sufficiently stabilized was measured as the peel strength. The results are shown in Table 2 below.

[0048]

[Table 2]

As is evident from Table 2, the electrodes of Examples 7 to 8 having a structure in which the slurry prepared while being kept at 20 ° C. or lower was applied to the current collector were not controlled to a temperature in the above range. It can be seen that the peel strength can be improved as compared with the electrode of Comparative Example 3 including the prepared slurry. In particular, in Example 7, in which the slurry temperature during preparation was 10 ° C., the peel strength was at least three times that of Comparative Example 3, and it can be seen that the peel strength could be significantly improved. Examples 9 to 12 Cobalt oxide (Co ₃ O ₄ ) and lithium carbonate (Li ₂ C)
O ₃ ) was mixed at a molar ratio of Li: Co of 1: 1 and heat-treated at 850 ° C. for 3 hours in an oxygen stream to obtain LiCoO ₂ powder. The obtained L
No water washing was performed to remove the alkaline component in the iCoO ₂ powder.

Two kinds of slurries were prepared in the same manner as in Examples 1 to 5, except that the above-mentioned LiCoO ₂ powder was used as an active material and the temperature of the slurry during preparation was set to the value shown in Table 3 below.

Each of the obtained slurries was bisected, and each was left in a thermostat controlled at a temperature shown in Table 3 below. Comparative Example 4 Examples 9-1 except that tap water was circulated through a cooling pipe attached to the outer wall of the container, and a slurry was prepared by stirring the electrode material in the container while maintaining it at 49 ° C.
A slurry was prepared in the same manner as in 2.

The obtained slurry was left in a thermostat controlled at a temperature shown in Table 3 below. Example 9-
The viscosity change of the slurries of Example 12 and Comparative Example 4 was measured using a B-type viscometer, and the results are shown in FIG.

[0053]

[Table 3]

As is apparent from FIG. 2, the slurries of Examples 9 to 12 prepared while being kept at 20 ° C. or lower were
It can be seen that the increase in viscosity during standing can be suppressed as compared with Comparative Example 4 prepared without performing such temperature control. In particular, Examples 1-2, which were stored at 10 ° C. or less after preparation,
It can be seen that the viscosity is almost constant over a long time. Examples 13 to 16 Manganese dioxide (MnO ₂₎ and lithium nitrate (LiNO
₃ ) was mixed with Li at a molar ratio of Mn of 1: 2 at a temperature of 450 ° C. for 30 hours in an oxygen stream, and then 75%.
LiMn ₂ O ₄ by heat treatment at 0 ° C. for 72 hours
A powder was obtained. Note that washing with water for removing an alkaline component in the obtained LiMn ₂ O ₄ powder was not performed.

Two kinds of slurries were prepared in the same manner as in Examples 1 to 5, except that the above-mentioned LiCoO ₂ powder was used as an active material and the temperature of the slurry during preparation was set to the value shown in Table 4 below.

The obtained slurry was divided into two parts, each of which was left in a thermostat controlled at a temperature shown in Table 4 below. Comparative Example 5 Tap water was circulated through a cooling pipe attached to the outer wall of the container, and the slurry was prepared by stirring the electrode material in the container while maintaining it at 44 ° C.
A slurry was prepared in the same manner as in No. 16.

The obtained slurry was left in a thermostat controlled at a temperature shown in Table 4 below. Example 13 abandoned
The viscosity changes of the slurries of Nos. To 16 and Comparative Example 5 were measured using a B-type viscometer, and the results are shown in FIG.

[0058]

[Table 4]

As is clear from FIG. 3, the slurries of Examples 13 to 16 prepared while maintaining the temperature at 20 ° C. or less were prepared in Comparative Example 5 prepared without such temperature control.
It can be seen that the increase in viscosity during standing can be suppressed as compared to In particular, Example 13 stored at 10 ° C. or less after preparation
It can be seen that in the case of -14, the viscosity is almost constant over a long period of time. Examples 17 to 20 The binder was vinylidene fluoride-tetrafluoroethylene-
Except for changing to a copolymer of hexafluoropropylene and setting the temperature of the slurry during preparation to the value shown in Table 5 below,
Two types of slurries were prepared in the same manner as in Examples 1 to 5.

Each of the obtained slurries was bisected, and each was left in a thermostat controlled at a temperature shown in Table 5 below. Comparative Example 6 Tap water was circulated through a cooling pipe attached to the outer wall of the container, and the slurry was prepared by stirring the electrode material in the container while maintaining the electrode material at 51 ° C.
A slurry was prepared in the same manner as in Example 20.

The obtained slurry was left in a constant temperature bath controlled at the temperatures shown in Table 5 below. Example 17 neglected
Viscosity changes of the slurries of Comparative Examples Nos. To 20 and Comparative Example 6 were measured using a B-type viscometer, and the results are shown in FIG.

[0062]

[Table 5]

As is apparent from FIG. 4, the slurries of Examples 17 to 20 prepared while being kept at 20 ° C. or lower were Comparative Example 6 prepared without such temperature control.
It can be seen that the increase in viscosity during standing can be suppressed as compared to In particular, Example 17 stored at 10 ° C. or below after preparation
It can be seen that the viscosity of # 18 to # 18 is almost constant over a long period of time.

Therefore, from Examples 17 to 20, even when the copolymer was used as the binder, the change in viscosity showed the same tendency as that when polyvinylidene fluoride was used as the binder, It was confirmed that curing could be suppressed. Examples 21 to 23 LiNiO ₂ powder was obtained in the same manner as in Examples 1 to 5. The LiNiO ₂ powder and acetylene black were added to a solution of polyvinylidene fluoride dissolved in N-methylpyrrolidone, and the resulting suspension was stirred with a dissolver while maintaining the temperature at 10 ° C., and mixed to obtain LiNiO 2.
₂ , the weight ratio of acetylene black (AB) and polyvinylidene fluoride (PVdF) (LiNiO ₂ : AB: PV
Three types of slurries having compositions in which the weight ratio of dF) to PVdF to LiNiO ₂ was as shown in Table 6 below were prepared.
The temperature control during preparation was performed in the same manner as in Examples 1 to 5.

For each of the obtained slurries, 0 ° C., 10
C., 20 ° C., the state of the slurry after 12 hours when left in a constant temperature bath controlled at 45 ° C. was observed.
When the viscosity of the slurry is 10,000 mPa · s or more and 20,000 mPa · s
, those in which the viscosity of the slurry became 20,000 mPa · s or more due to the progress of curing were evaluated as △, and those in which the curing was further advanced and viscosity measurement was impossible were evaluated as ×. The results are shown in Table 6 below.

[0066]

[Table 6]

As is clear from Table 6, the slurries of Examples 22 to 23 having compositions in which the weight ratio of the binder to the active material is 5.5 × 10 ⁻² or more are 5.5 or more.
It can be seen that curing before coating can be suppressed as compared with the slurry of Example 21 having a composition smaller than × 10 ^-2 .

[0068]

As described in detail above, according to the method for producing an electrode for a non-aqueous solvent secondary battery of the present invention, a polyvinylidene fluoride-based fluororubber can be produced by a simple operation of temperature control even in the presence of an alkali component. It is possible to suppress or avoid the hardening of the slurry containing, eliminating the need for the treatment of removing the alkali component in the active material, making it possible to prepare and store a large amount of the slurry in advance, and the slurry and the current collector This has a remarkable effect, such as improving the adhesion to the electrode and enabling mass production of high-performance electrodes.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between a slurry standing time and a slurry viscosity in Examples 1 to 6 of the present invention.

FIG. 2 is a characteristic diagram showing a relationship between a slurry standing time and a slurry viscosity in Examples 9 to 12 of the present invention.

FIG. 3 is a characteristic diagram showing a relationship between slurry standing time and slurry viscosity in Examples 13 to 16 of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between slurry standing time and slurry viscosity in Examples 17 to 20 of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Yamada 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock company Toshiba Kawasaki Plant (72) Inventor Shinji Arai 72, Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa Stock Incorporated Toshiba Kawasaki Plant (72) Inventor Moto Kanda 72 Horikawa-cho, Saiwai-ku, Kawasaki City, Kanagawa Stock Company Toshiba Kawasaki Plant

Claims (3)

[Claims] A step of preparing a slurry containing a composite oxide of lithium and at least one metal selected from cobalt, nickel and manganese as an active material, a vinylidene fluoride-based fluororubber as a binder and an organic solvent; Applying the slurry to the current collector, or filling the current collector with the slurry, wherein the slurry contains at least the active material, the binder, and the organic solvent. A method for producing an electrode for a non-aqueous solvent secondary battery, characterized by being prepared by stirring an electrode material while maintaining it at 20 ° C. or lower. 2. A step of preparing a slurry containing a composite oxide of at least one metal selected from cobalt, nickel and manganese and lithium as an active material, a vinylidene fluoride fluororubber as a binder and an organic solvent. A method for manufacturing an electrode for a non-aqueous solvent secondary battery, comprising: a step of storing the slurry at 20 ° C. or lower; and a step of applying or filling the slurry to a current collector. 3. The method for producing an electrode for a non-aqueous solvent secondary battery according to claim 1, wherein the composite oxide is LiNiO ₂ .