WO2006025600A1

WO2006025600A1 - Method for maintaining positive electrode material composition for lithium secondary battery

Info

Publication number: WO2006025600A1
Application number: PCT/JP2005/016466
Authority: WO
Inventors: Alan Vallee; Paul-Andre Lavoie; Kazuhiko Murata; Fumihide Tamura; Hiromoto Katsuyama; Taketo Toba
Original assignee: Nippon Shokubai Co., Ltd.
Priority date: 2004-09-03
Filing date: 2005-09-01
Publication date: 2006-03-09
Also published as: JPWO2006025600A1

Abstract

Disclosed is a method for maintaining a positive electrode material composition for lithium secondary batteries during transportation/storage which enables to maintain the positive electrode material composition in such a condition that the battery performance of a lithium secondary battery which uses a positive electrode produced from the positive electrode material composition is prevented from deterioration. Specifically disclosed is a first method for maintaining a positive electrode material composition for lithium secondary batteries, namely a method for maintaining a positive electrode material composition which essentially contains apolymer, an electrode active material and a conductive assistant. This method is characterized in that when the weight average molecular weight of the polymer in the composition before storage is represented by Mw0 and the weight average molecular weight of the polymer in the composition after storage of 18 days is represented by Mw, the decrease rate (DMw) of the weight average molecular weight represented by the formula (1) below is not more than 10%. DMw(%) = [(Mw0 - Mw)/Mw0] × 100 (1)

Description

Method of storing positive electrode material composition for lithium secondary battery

The present invention relates to a method of storing a positive electrode material composition used for producing a lithium secondary battery. Specifically, when transporting and storing the positive electrode material composition for a lithium secondary battery, the positive electrode material composition such that the battery performance of the lithium secondary battery produced by the positive electrode material composition is not deteriorated. On how to save Ming background technology

The positive electrode used in the lithium secondary battery includes: a polymer as a matrix, an electrolyte salt for transporting ions, an electrode active material for storing ions, a conductive aid, and a solvent, if necessary. In general, it is generally manufactured using a composition obtained by kneading as a material, and so far, various batteries using a positive electrode formed using such a composition as a material have been proposed (for example, a patent) Reference 1 to 4). Specifically, the positive electrode is produced by extruding the composition as described above, or by casting it by solution casting and devolatizing the solvent.

By the way, conventionally, when manufacturing a positive electrode industrially, it is normal to continue the step of mixing the polymer, the electrolyte salt, the electrode active material, the conductive auxiliary agent and the like, and the step of forming the obtained mixture. Met. That is, the polymer serving as the raw material of the positive electrode, the electrolyte salt, the electrode active material, the conductive auxiliary agent and the like are mixed immediately before molding of the positive electrode, and each raw material used in manufacturing the positive electrode is usually procured individually. It is done.

[Patent Document 1] Special Table 2 0 0 2-5 3 5 2 3 5

[Patent Document 2] US Patent No. 5 7 5 5 9 8 5

[Patent Document 3] International Publication No. 0 3 Z 7 5 3 7 5 Breadlet

[Patent Document 4] International Publication No. 0 3 Z 9 2 0 1 7 Pamphlet Abstract of the Invention Problems to be Solved by the Invention

However, in consideration of simplification of the process of manufacturing the positive electrode, etc., among the above-mentioned raw materials of the positive electrode, one or all of the electrolyte salt, the electrode active material and the conductive additive are mixed (kneaded) in a polymer in advance. In some cases, it takes a form of procuring products as raw materials. However, when such a procurement form is adopted, the battery performance is significantly inferior to the case where a battery is manufactured using a positive electrode obtained by individually procuring each raw material and mixing (kneading) immediately before molding. There was a problem sometimes. Such problems usually occur when a polymer as a matrix is previously mixed (kneaded) with other raw materials and stored for a certain period before being used for molding for transportation or storage. Therefore, this is considered to be the cause of the decrease in battery performance. Therefore, the problem to be solved by the present invention is that, in transporting and storing the positive electrode material composition, the battery performance of the lithium secondary battery using the positive electrode produced by the positive electrode material composition is not deteriorated. An object of the present invention is to provide a method of storing a positive electrode material composition for a lithium secondary battery, which can store the positive electrode material composition. Means to solve the problem

The present inventors diligently studied to solve the above-mentioned problems. As a result, the molecular weight of the polymer serving as the matrix tends to slightly decrease in the coexistence of the electrode active material and the conductive aid, and it is a minor level that does not cause any problems in applications other than such applications of the positive electrode material. It has been found that the decrease in molecular weight of the polymer has a significant adverse effect on cell performance in the positive electrode material for lithium secondary batteries. Then, based on this finding, when storing a positive electrode material composition that essentially contains a polymer, an electrode active material and a conductive support agent, the degree of molecular weight reduction of the polymer is acceptable so long as the battery performance is not adversely affected. As a result of examination, when the reduction rate of the weight average molecular weight of the polymer in the composition when the composition is stored for 18 days is 10% or less, after further storing (transporting and storing) under the same conditions, It has been found that even when a positive electrode material is produced and a lithium secondary battery is produced using the positive electrode material, the battery performance is hardly affected, and furthermore, the weight of the polymer when stored for 18 days in this way In order to reduce the average molecular weight to 10% or less, temperature control should be performed at 50 ° C or less in an inert gas atmosphere and at 5 ° C or less in an air atmosphere. Headline, The present invention has been completed.

That is, the first method for storing a positive electrode material composition for a lithium secondary battery according to the present invention is a method for storing a positive electrode material composition that essentially includes a polymer, an electrode active material and a conductive additive, Mw weight average molecular weight of the polymer in the previous composition. When the weight average molecular weight of the polymer in the composition when stored for 18 days is Mw, the reduction rate (D _Mw ) of the weight average molecular weight represented by the following formula (1) is 10% or less It is characterized by

D _Mw (%) = [(Mw.-Mw) ZMw ₀ ] XI 0 0 (1)

A second method of storing a positive electrode material composition for a lithium secondary battery according to the present invention is a method of storing a positive electrode material composition that essentially includes a polymer, an electrode active material, and a conductive additive, and includes an inert gas atmosphere. It is characterized in that temperature control is performed to 5 or less under an atmosphere.

A third method of storing a positive electrode material composition for a lithium secondary battery according to the present invention is a method of storing a positive electrode material composition that essentially includes a polymer, an electrode active material, and a conductive support agent, and is performed under an air atmosphere. Temperature control to 5 ° C or less. Effect of the invention

According to the storage method of the positive electrode material composition for a lithium secondary battery of the present invention, the decrease in molecular weight of the polymer in the positive electrode material composition is suppressed at the time of transportation, storage and the like, and the positive electrode manufactured by the positive electrode material composition. The battery performance of the lithium secondary battery can be prevented from being degraded. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the method for storing the positive electrode material composition for a lithium secondary battery according to the present invention (hereinafter sometimes referred to as “the storage method according to the present invention”) will be described in detail. The present invention is not bound to be clear, and modifications can be made as appropriate without departing from the spirit of the present invention other than the following examples.

[Positive material composition for lithium secondary battery]

The positive electrode material composition for a lithium secondary battery to be stored in the storage method of the present invention is a composition essentially comprising a polymer, an electrode active material and a conductive auxiliary.

The polymer which is an essential component of the positive electrode material composition is not particularly limited as long as it is usually used as a matrix of a positive electrode material for a lithium secondary battery, and is an ion conductive polyether polymer. Is preferred. In particular, it is preferable that the polymer is an ethylene oxide-based polymer in that the battery performance as a positive electrode material can be further improved. The ethylene oxide-based polymer suitable as the polymer is, for example, ethylene oxide. Structural formula below (1)

(Wherein, R a (where R a represents a carbon number of 1 to 16, any of alkyl group, cycloalkyl group, aryl group, aralkyl group, (meth) ataryloyl group and alkenyl group) Or a single CH ₂ — O— R e — R a group (where R e is a single (CH ₂ — CH ₂ — 0) p — structure (p is an integer from 0 to 10)) It can be obtained by polymerizing a mixture of monomers essentially comprising the substituted oxylan compound shown in the above). The monomer mixture may contain other monomers in addition to ethylene oxide and the substituted alkoxy compound. The proportion of each monomer in the monomer mixture is not particularly limited and may be set appropriately.

Examples of the substituted oxylan compound represented by the above structural formula (1) include propylene oxide, butylene oxide, 1,2- epoxypentane, 1,2-epoxyhexane, 1,2-epoxyoctane, cyclohexoxide and styrene oxide. Or methyl glycidyl ether, cetyl dalysidyl ether, ethylene glycol methyl glycidyl ether and the like. Also, assuming that the substituent is a crosslinkable substituent, for example, epoxy butene, 3, 4-epoxy 1 1-pentene, 1, 2-epoxy 1, 5 9-cyclododecadiene, 3, 4- Epoxy, 1-butyl cyclohexene, 1, 2-epoxy, 5-cyclo-Otene, glycidyl acrylate, glycidyl methacrylate, glycidyl sorbate and glycidyl 1 · xanoate or or buli glycidyl ether, aryl Glycidyl ether, 4-vinylcyclohexyl glycidyl ether, _a -terpenyl glycidyl ether, cyclohexenyl methyl dalysyl ether, 4-vinylbenzyl glycidyl ether, 4-arylbenzyl glycidyl ether. Sylkyl ether, ethylene glycol palyl glycidyl ether, ethylene glycol vinyl glycidyl ether, diethylene glycol palyl glycidyl ether, diethylene glycol vinyl dalysyl ether, triethylene glycol palyl glycidyl ether, triethylene glycol vinyl dalysyl ether, oligo Examples thereof include ethylene glycol glycidyl ether and oligoethylene glycalyl vinyl dalysyl ether. The number of substituted oxylan compounds may be one or two or more.

In order to obtain the ethylene oxide-based polymer, the monomer mixture may be polymerized while stirring in a solvent. The method for such polymerization is not particularly limited, but preferred examples include a solution polymerization method and a precipitation polymerization method. Among them, the solution polymerization method is more preferable because it has excellent productivity. A solution polymerization method in which polymerization is performed while supplying each monomer as a raw material to a previously charged solvent is particularly preferable because of safety such as easy removal of heat of reaction. In addition, in the above-mentioned polymerization, a commonly used polymerization initiator, an antioxidant (for example, a general-purpose phenol-based antioxidant etc.), a solubilizer, etc. may be added. ,.

Examples of the solvent include aromatic hydrocarbon solvents such as benzene, toluene, xylene and ethylbenzene; and aliphatic hydrocarbons such as heptane, octane, n-hexane, n-pentane and 2, 2, 4-trimethylpentane. Solvents; Alicyclic hydrocarbon solvents such as cyclohexane and methylcyclohexane; Ether solvents such as jetyl ether, dibutyl ether and methyl butyl ether; Solvents for ethylene diallyl dialkyl ethers such as dimethoxetane; THF Organic solvents which do not contain active hydrogen such as hydroxyl groups such as cyclic ether solvents such as (tetrahydrofuran) and dioxan are preferable, and toluene, xylene and n-hexane are more preferable. Furthermore, the solvent is an organic solvent which does not contain water at all, but the problem is that the hydroxide formed by the reaction of water and metal ions etc. becomes an insulating layer and the cycle characteristics of the battery are deteriorated. It is preferable to avoid it.

The weight average molecular weight (Mw) of the polymer is not particularly limited, but is preferably 2 0 0 0 5-5 0 0 0 0 0, more preferably 3 0 0 0 0 3 0 0 , 0 0 0, and more preferably 4 0, 0 0 0 to 2 0 0, 0 0 0. If the weight average molecular weight is less than 20, 00, there is a risk that tack will occur when forming into a positive electrode, while if it exceeds 500, the forming itself becomes difficult, Processability and handling may be reduced.

The molecular weight distribution (MwZMn) of the polymer is not particularly limited, but is preferably 3 or less, more preferably 2 or less. When the molecular weight distribution is more than 3, there is a risk that tackiness may occur during molding to form a positive electrode, or poor and indling properties may deteriorate.

The electrode active material, which is an essential component of the positive electrode material composition, has an electrochemical effect on the insertion and desorption of Li ions, and is generally used to form a positive electrode. No particular limitation is imposed, and examples thereof include lithium vanadium complex oxide, lithium cobalt complex oxide, lithium manganese complex oxide, lithium nickel complex oxide, vanadium oxide and the like, among which L ix V y O z (However, x, y and z are each independent of each other, and 0 x ≤ 2, y = (mx + 2 z) n, and z = (mx + ny) / 2 (where m is L i is a valence of i, n is a valence of V and there is a real number of 4 or more. Ru. It is particularly preferable that L i) can more effectively insert and desorb L i ions. The electrode active material may be only one type, or two or more types.

The proportion of the electrode active material in the positive electrode material composition is not particularly limited, but is preferably, for example, 0.1 to 50 times by weight the polymer, and more preferably 0.3 to 2 times. It is preferable that it is 0 times, more preferably 0.5 to 10 times. If the amount of the electrode active material is too small, the function as the positive electrode may not be sufficiently exhibited. On the other hand, if the amount of the electrode active material is too large, molding may be difficult.

The conductive auxiliary agent, which is an essential component of the positive electrode material composition, is not particularly limited as long as it is generally used to form a positive electrode, and examples thereof include acetylene black, ketjen black, Graphite, etc. Can be mentioned. The conductivity assistant may be only one kind or two or more kinds.

The proportion of the conductive auxiliary agent in the positive electrode material composition is not particularly limited, but is preferably 1 to 20 parts by weight, more preferably 2 parts by weight with respect to 100 parts by weight of the electrode active material, for example. It should be about 15 parts by weight. If the amount of the conductive additive is too small, the conductivity of the positive electrode may be insufficient. If the amount of the conductive additive is too large, molding may be difficult.

The positive electrode material composition preferably also contains an electrolyte salt required to form a positive electrode. The electrolyte salt is not particularly limited as long as it is usually used to form a positive electrode, and examples thereof include, but are not limited to, for example, fluorine ion, chloride ion, bromine ion, iodine ion, heptafluoropropyl Sulfonate ion, bis (trifluoromethanesulfonyl) imide ion, bis (heptafluoropropione les / lephoni imidate ion, trifnoleoporte sulfonate ion, tetrafluoroboronate ion, nitrate ion, As s F _6- , PF _6- , stearyl sulfonate ion, octyl sulfonate ion, dodecyl benzene sulfonate ion, naphthalene sulfonate ion, dodecyl naphthalene sulfonate ion, and 7,7,8,8-tetracyanol p-quinodimethane ion Anions selected from the group consisting of A salt, and the like. Among _{these, L i BF 4, L i} PF 6, L i CF 3 S 0 3, L i C 4 F 9 S_〇 _{_{3, L i N (CF 3}} S 0 2) ₂ , L i N (C ₂ F ₆ S 0 ₂ ) ₂ is more preferable The number of electrolyte salts may be only one, and may be two or more. The proportion is not particularly limited, but for example, when the polymer is a polyether polymer, the total number of moles of ether oxygen in the polyether polymer and the value of the number of moles of the electrolyte salt are 1 to 36. It is preferable that the ratio be 3 to 3, more preferably 6 to 3. If the amount of the electrolyte salt is too small, the ion conductivity may be reduced, On the other hand, even if the amount of electrolyte salt is too large, the effect of improving ion conductivity corresponding to the amount of electrolyte salt does not appear, which is economically disadvantageous. It is

The positive electrode material composition may contain a solvent. The solvent is one that is finally removed by means such as degassing when molded into a positive electrode, but by including the solvent in the composition, the polymer such as the electrolyte salt etc. can be obtained. The components that are difficult to dissolve can be dissolved in a solvent to facilitate mixing of the components, or the viscosity can be adjusted so that they can be easily handled during transport and storage. The solvent is not particularly limited, and can be used, for example, when obtaining the above-mentioned ethylene oxide polymer. . The proportion of the solvent in the positive electrode material composition is not particularly limited, and may be set as appropriate. When the polymer is obtained by a polymerization method using a solvent as in the case of the above-mentioned ethylene oxide-based polymer, the polymerization reaction solution contains the solvent, so the polymerization reaction solution is used as it is for the positive electrode material. It may be mixed as a component of the composition, or after the solvent is once removed from the polymerization reaction solution, another solvent may be added as a component of the positive electrode material composition.

The positive electrode material composition further comprises, if necessary, for example, an antioxidant, a light stabilizer, a lubricant, an antistatic agent, a reinforcing agent, a filler, an antioxidant (for example, a general-purpose phenol-based antioxidant etc.), etc. The additive may be suitably contained in the range which does not impair the effect of the present invention. In addition, the positive electrode material composition may contain, for example, a component contained in a polymerization reaction solution obtained by polymerization when obtaining the polymer.

The positive electrode material composition to be stored in the storage method of the present invention is, for example, a solution, a slurry, a solution, particles, pellets, fine particles, a desired shape (a size larger than particles or pellets). The polymer, the electrode active material and the conductive auxiliary agent may be mixed or kneaded, if necessary, to volatilize, granulate, dry, adjust, etc. It is obtained by applying moisture and the like. From the viewpoint of ease of handling, etc., the solidified material obtained by mixing or kneading each component and removing the solvent by devolatilization (particulate, pellet, fine particles, lump of desired shape, etc. And the like, and more preferably one obtained by granulating in the form of particles, pellets, or mass. Further, the water content in the positive electrode material composition is to avoid the problem that the hydroxide layer formed by the reaction of water and metal ion becomes an insulating layer and the cycle characteristics of the battery are deteriorated. The lower one is preferable, and from this point of view, the composition obtained through at least one of devolatilization, drying and humidity control is said to be preferable.

For the method of mixing or kneading the above-described components that essentially contain the polymer, the electrode active material, and the conductive auxiliary agent, the method of devolatilization, the method of granulation, the method of drying, the method of humidity control, etc. A conventionally known method may be adopted as appropriate.

[Preservation method of the present invention]

According to the first storage method of the storage method of the present invention, before storage, the weight average molecular weight of the polymer in the positive electrode material composition is Mw. When the weight average molecular weight of the polymer in the composition when stored for 18 days is Mw, the reduction rate (D _Mw ) of the weight average molecular weight represented by the following formula (1) is 10% or less It is characterized by Preferably, the reduction rate (D _Mw ) when stored for 18 days is 5% or less.

D _Mw (%) = [(Mw. 1 Mw) / Mwo) XI 0 0 (1)

Thus, if it is a storage method in which the reduction rate (D _Mw ) is 10% or less, then after further storing (transporting and storing) under the same conditions, a positive electrode material is prepared, and lithium is produced using the positive electrode material. Even when a secondary battery is manufactured, good battery performance can be exhibited. In order for the reduction rate (D _Mw ) to be 10% or less, for example, it is preferable to adopt the second or third storage method of the present invention described later. Also, for example, the storage method in which the inert gas in the second storage method of the present invention described later is replaced with dry air having a dew point of 40 ° C. or less, preferably 50 ° C. or less is preferable. It is effective as a means to make the reduction rate (D _Mw ) 10% or less In the first storage method, in particular, when the positive electrode material composition does not contain the electrolyte salt, the reduction rate (D _Mw ) when stored for 18 days as described above is 10%. In addition to the requirement that it is the following, the reduction rate of the molecular weight when stored for 3 days (when the weight average molecular weight of the polymer in the composition when stored for 3 days is Mw, it is represented by the above formula (1) The weight-average molecular weight reduction rate is preferably 10% or less, preferably 5% or less. In the second storage method of the storage methods of the present invention, it is important to control the temperature to 50 ° C. or lower in an inert gas atmosphere. That is, the positive electrode material composition is stored in a space filled with an inert gas and temperature-controlled to 50 ° C. or less. Here, the space filled with the inert gas (ie, the inert gas atmosphere) does not necessarily have to have 100% of the inert gas, and specifically, the composition is stored. If the space is filled with an inert gas such that the oxygen concentration in the space to be reduced is 15 V o 1% or less, more preferably 10 V o 1% or less, and even more preferably 7 V o 1% or less. Good. The flow rate, time, and the like at the time of filling the inert gas may be appropriately set so that the oxygen concentration in the space falls within the above range, in consideration of the size of the space and the like. Alternatively, a mixed gas of an inert gas and air may be filled so that the oxygen concentration in the space falls within the above range. The inert gas is not particularly limited, and examples thereof include nitrogen gas, argon gas, and helium gas. The inert gas may be only one kind or two or more kinds.

In the third storage method of the storage methods of the present invention, it is important to control the temperature to 5 ° C. or less in an air atmosphere. That is, the positive electrode material composition is stored in a space filled with air and temperature-controlled to 5 ° C. or less. Here, the air filled in the space for storing the positive electrode material composition may be dry air having a low dew point (for example, a dew point of 40 ° C. or less) or normal air (a dew point is not high yet). It may be dry air). That is, if the temperature exceeds 5 ° C. (for example, room temperature), as described above, the space for storing the positive electrode material composition by filling with an inert gas or the following dry air with a dew point of 140 or the like. Although it is important to reduce the water content to suppress the reduction rate (D MW), in the third storage method in which the temperature is controlled to 5 ° C. or less, the inclusion of a space for storing the positive electrode material composition never water content affects the rate of decrease (D _Mw), is the great difference in the reduction rate even be a dry air a normal air (D _Mw) does not occur.

In the storage method of the present invention, the positive electrode material composition may be stored as it is, for example, in an apparatus used for preparing a composition such as mixing, kneading, devolatilization, drying, conditioning, granulation, etc. The container or bag may be filled and stored, and the storage form is not limited, but in the first storage method, the inert gas atmosphere, ie, the space filled with the inert gas is maintained It is preferable to store in a sealed device, container, bag, etc. In addition, when selecting an apparatus, container, bag, etc. for storing the positive electrode material composition, it is preferable to select one made of a material having the lowest gas permeability and hygroscopicity. For example, in the case of storage with a device, it may be stored in a batch type storage device such as a hopper or silo, and in the case of storage in a container, it may be stored in a metal drum or container, etc. If you do, you may use an aluminum foil bag or a multilayer film bag containing an aluminum foil layer (in particular, in consideration of heat sealability, a bag made by laminating aluminum foil on resin film such as polyethylene or polypropylene) It is good if it preserve | saves with preferable etc. Also, put a bag filled with the composition into a container, etc. Combining bags is also effective in reducing gas permeability and hygroscopicity. In the storage method of the present invention, in the case where the positive electrode material composition is a solidified material, it is preferable that the solidified materials adhere to each other and not form a lump, even if a plurality of such materials are stored. Here, the solidified material is not in the form of a solution or paste, but is, for example, in the form of particles, pellets, or lumps of a desired form. A plurality of positive electrode material compositions which are in a solidified state are usually stored in a single container, bag or the like, in which case the solidified bodies adhere to each other to form a lump (so-called blocking) Easily). In particular, in the case of a composition containing an electrolyte salt, the melting point of the composition is lowered compared to the case where the composition does not contain an electrolyte salt. It becomes easy to become. When the positive electrode material composition is in a so-called blocking state, the deflection when supplying the composition from the feeder 1 to the extruder becomes large when it is molded to produce a positive electrode, and stable feeding can not be performed, and molding is performed. The problem arises that the dimensions and the like of the subsequent molded product are not uniform. In order to make the solidified products of the composition adhere to each other and not form a lump, it is preferable that fine particles are added during storage. Specifically, the fine particles were attached to the surface of the positive electrode material composition which is a solidified product by adding and mixing it in a space (apparatus, container, bag, etc.) for storing the fine particles together with the solidified positive electrode material composition. If it is stored as a state, or when a positive electrode material composition which is a solidified product is obtained, fine particles are also added together with the above-mentioned components so as to be stored as a state in which fine particles are contained inside the positive electrode material composition. do it.

The fine particles are not particularly limited as long as the specific surface area of the particles is 10 m ² / g or more in nitrogen adsorption specific surface area (BET method). The specific surface area of the fine particles is a nitrogen adsorption specific surface area (BET method), preferably 2 O m ² g or more, more preferably 40 m ² / g or more, and further preferably 10 O n ^ Z g It is good that it is above. If the specific surface area of the fine particles is less than 10 m ² Z g in nitrogen adsorption ratio surface area (BET method), the adhesion preventing effect of the solidified positive electrode material compositions is reduced, so the effect is sufficient. However, if the amount of the fine particles added is increased excessively, the battery characteristics will be impaired.

As specific examples of the fine particles, for example, silica particles, carbon particles, alumina particles, titanium particles, magnesia particles and the like can be used. Among them, it is particularly preferable to use a silica particle from the viewpoint of having the least electrical influence and easy dissolution uniformly in the positive electrode material composition. The silica particles are not particularly limited, but those having a particle diameter of less than 60 / im are preferable. The silica particles are preferably hydrophobic, and for example, “Aerosil R 9 2 2” or “Aerosil R 9 7 4” manufactured by Nippon Aerosil Co., Ltd. is preferably used as a commercial product.

Although the addition amount of the fine particles is not particularly limited, for example, it is preferable to be 0.1 to 1% by weight with respect to the positive electrode material composition.

The positive electrode material composition stored by the storage method of the present invention may be formed according to the usual method after blending the components required for the positive electrode material as necessary, for example, including it if it does not contain an electrolyte salt. Can be used as the positive electrode. The lithium battery produced by the usual method using the positive electrode obtained in this manner can be used in various batteries such as short test, cycle characteristics, etc. Example that becomes excellent in performance

EXAMPLES The present invention will be more specifically described below by Examples and Comparative Examples, but the present invention is not limited thereto. In the following, “%” means “% by weight” and “parts” means “parts by weight” unless otherwise noted.

The following examples · The molecular weight reduction rate in the comparative example is Mw the initial weight average molecular weight of the polymer in the positive electrode material composition before storage. The weight-average molecular weight of the polymer in the composition after storage is M w, which is calculated based on the following formula.

Molecular weight reduction rate (%) = [(Mw. 1 Mw) / Mw. ] X I 00

The weight average molecular weight of the polymer in the positive electrode material composition was measured as follows. That is, acetonitrile is added to the composition to make a 1% solution, and after sufficiently stirring with a Tutch mixer and shaker to dissolve the polymer component, the insoluble matter is filtered by a filter (non-aqueous system, 0.45 μπι). The resulting filtrate is diluted with an eluent (acetonitrile / water-water-sodium borate mixture solution) to give a sample, and a GPC apparatus (Tosoh “HCL_8120GPC”) is used as a sample, and a standard molecular weight sample of polyethylene oxide. It calculated | required by the calibration curve produced using.

Production Example 1 Preparation of Positive Electrode Material Composition (A) Containing Electrolyte Salt

After replacing the air in a 100 L reactor (this reactor is called “Reactor A”) equipped with Max Blend wings, a hot water jacket, and an addition port with nitrogen gas, the hot water jacket temperature is raised to 70 ° C. Polymer (Ethylene butylene butylene oxide copolymer: weight average molecular weight (Mw) 124, 000, molecular weight distribution (MwZMn) 1 which had been warmed and kept at 80 ° C. in advance. 33. 30 parts of a solution of 45) in toluene (solid content 45.8%) was added. Next, 3.28 parts of lithium bis (trifluoromethanesulfone) imide (Li ₃ N (CF ₃ S 0 ₂ ) ₂ ) was introduced into the reactor from the hopper as a lithium salt. Thereafter, the residue remaining in the hopper or piping was washed away with 6,000 parts of toluene into the reactor, and then stirred at an internal temperature of 70 and a 90 rpm rotation for 2 hours.

Next, air in a 100 L reactor (this reactor is referred to as “Reactor B”) equipped with a stirring blade (“Super blend wing”, Sumitomo Heavy Industries, Ltd.), a warm water jacket, and an addition port. The reactor is replaced with nitrogen, and then, in the reactor, 0.50 076 parts of a phenol-based antioxidant (“Cysnox BB” manufactured by AP Corporation, 30 parts of toluene, and a mixture of an electrode active material and a conductive aid (“L um oxide / carbonblend "(US AVE S TOR LLC) 31. 68 parts were introduced one by one. After that, the residue remaining in the hopper and piping etc. is washed away with 10.0 parts of toluene into the reactor, and then the inner blade rotation is 75 rpm and the outer blade rotation is 29 rpm at normal temperature and pressure for 30 minutes. Stir and mix uniformly. After that, the operation of pressurizing the inside of the reactor to 1.6 kg / cm ² with nitrogen and depressurizing to 10 O mmHg was repeated several times to remove excess water and dissolved oxygen in the system.

Next, while stirring the inside of the reactor B with the inner blade rotation 75 rpm and the outer blade rotation 29 rpm, the piping of the reactor A is made via the piping previously attached to connect the reactor A and the reactor B. Contents (mixed solution of polymer and lithium salt) 42. 58 parts are charged into reactor B, then heated with a water jacket and stirred at 50 for 2 hours to obtain a uniform slurry solution did. Next, using a 30 mm ψ twin-screw extruder ("BT_30-S 2" manufactured by BLASTIC INSTRUMENT RESEARCH INSTITUTE), the above reactor via a gear pump at a biaxial rotation speed of 100 rpm and an internal temperature of 100 ° C. The slurry solution was fed, and degassing was applied under a reduced pressure of 349 Torr, and the solvent (toluene) was distilled off. Then, the rod-like body extruded from the outlet of the twin-screw extruder is formed into a sheet of 2 mm in thickness using a rolling two-roll ("8 x 20 BOX type roll machine" manufactured by Kansai Roll Co., Ltd.). The sheet was placed in a nitrogen-replaced bag, heat sealed, and stored in a refrigerator at 10 ° C. or less overnight. Next, the sheet material cooled to 9 ° C. is cut into a width of 4 mm and a length of about 3.7 mm using a sheet cutter (“30 £ -220 type” manufactured by Horai Co., Ltd.), and a square pellet is obtained. And The pellet is placed in a conical dryer (“vacuum tumble dryer” manufactured by Nissan Kogyo Co., Ltd.), and nitrogen is allowed to flow at a flow rate of 5 LZ, under conditions of 20 and a degree of vacuum of 6 Torr. After drying for a longer time, a pellet-like positive electrode material composition (A) was obtained.

Production Example 2 Preparation of Positive Electrode Material Composition (B) Containing No Electrolyte Salt

After stirring air in a 100 L reactor equipped with a stirring blade ("Super Blend Blade j Sumitomo Heavy Industries, Ltd."), a warm water jacket, and an addition port, the air in the reactor is replaced with nitrogen, Agent ("Yoshinox BB", manufactured by AP Corporation), 30 parts of Toluen, a mixture of an electrode active material and a conductive auxiliary ("Lithated vanadium oxide / carbonblend", manufactured by US AVE S TOR LLC) 23. 7 6 copies were introduced one by one. After that, the residue remaining in the hopper and piping etc. is washed away with 5.0 parts of toluene into the reactor and stirred at normal temperature, normal pressure for 30 minutes, inner blade rotation 75 rpm, outer blade rotation 29 rpm And mixed uniformly. Then, the operation of pressurizing the inside of the reactor to 1.6 kgzcm ² with nitrogen and depressurizing to 10 O mmHg was repeated several times to remove excess water and dissolved oxygen in the system. Then, a polymer (ethylene oxide butylene oxide copolymer: weight average molecular weight (Mw) 1 24,000, molecular weight distribution, which has been prewarmed to 80 ° C.

After 25 parts of a toluene solution (Mw / Mn) 1. 45) (solid content: 45.8%) was added, the temperature was raised with a warm water jacket, and internal blade rotation 75 rpm, normal pressure at 49 ° C for 1 hour. The mixture was stirred at an outer blade rotation of 29 rpm to obtain a uniform slurry solution. After that, the number of revolutions of both wings was set to 50 rpm for the inner wing and 24 rpm for the outer wing, and the heating of the hot water jacket was stopped overnight. The temperature of the slurry solution after one day was 36.2 ° C.

Next, 0.50 parts of a phenol-based antioxidant (“Y-Sinox BB” manufactured by AP Corporation) was charged into the reactor. After that, connect a pressure reduction line to the reactor, and apply a pressure reduction of 60 to 69 Torr at 47 to 49 ° C while stirring with inner blade rotation 75 rpm and outer blade rotation 29 rpm to distill off toluene. The mixture was de-pressurized with nitrogen to form a slurry solution having a solid content of about 64. 4%.

Next, after replacing the air of the KRC kneader (made by Kurimoto Koji Co., Ltd.) main body, supply line and outlet line with nitrogen gas, set the internal temperature to 89 ° C while rotating the kneader at 38 rpm. Set the slurry solution in the kneader main body from the reactor via a gear pump, first reduce the pressure to 27 OTo rr, and confirm that the toluene is stably distilled. Then, 26 7 T orr Degassing was applied under reduced pressure. Then, the melt extruded from the outlet of the KRC kneader is sent to the strand die (2 mm in diameter, 2 holes) via a gear pump, The mixture was extruded into a stream to obtain a 3 mm-diameter string. Next, the string-like material is first placed on a belt conveyor ("San Ye concha SJ Y_15-200" manufactured by Sanei Mfg. Co., Ltd.) installed under a nitrogen stream at room temperature, allowed to cool, and then surfaced under a nitrogen stream. It was placed on a single-belt crater at a temperature of 10 ° C. (“Steel-belt single cooler” manufactured by Nippon Steel Conveyor Co., Ltd.) and cooled, and then allowed to stand overnight under nitrogen flow for drying.

Next, the obtained string was cut into a round pellet having a length of about 3.65 mm using a strand cutter ("SFC-100" manufactured by Izu Chemical Co., Ltd.). The pellet is placed in a conical dryer ("vacuum tumble dryer" manufactured by Nissan Kogyo Co., Ltd.)

After passing nitrogen at a flow rate of 5 LZ, drying was carried out for more than 17 hours under conditions of 30 ° C. and a degree of vacuum of 1 l Torr, to obtain a pellet-like positive electrode material composition (B).

Example 1-1

Place the positive electrode material composition (A) in a sealable container (volume 30 OmL) equipped with a thermometer, a gas inlet and a valve outlet, and a lid, close the lid, and open the gas inlet and outlet valves. In this state, nitrogen gas is introduced into the vessel from the inlet at a flow rate of 1 O OmL Z minutes for 3.5 minutes to replace the air in the vessel with nitrogen gas, and then the gas outlet valve is closed immediately and the inlet valve is closed. Closed and sealed the container. Then, the container was placed in a thermostat so as to maintain the temperature in the container at 25 ± 5 ° C. (room temperature), and stored for 18 days. After that, the composition in the container was immediately analyzed by a GPC apparatus which prepared a calibration curve using a standard molecular weight sample of polyethylene oxide, and the weight average molecular weight of the polymer in the composition was measured to be 122,000. There was a molecular weight reduction rate of 1.6% with respect to the initial weight average molecular weight of 14,000 of the polymer in the positive electrode material composition (A).

Example 1 2 The positive electrode material composition (A) was stored in the same manner as in Example 1-1 except that nitrogen gas was changed to argon gas. Thereafter, in the same manner as in Example 1-1, the composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured to be 123,000, indicating that the positive electrode material composition (A) The molecular weight reduction rate was 0.8% with respect to the initial weight-average molecular weight of 124,000 of the polymer contained therein.

[Comparative Example 1 1 1]

Place the positive electrode material composition (A) in a sealable container (volume 30 OmL) equipped with a thermometer and a lid, close the lid, and close the container without replacing the inside of the container with nitrogen gas (at this time, The water content of the air in the container was about 6000 ppm) and the container was placed in a thermostat so as to maintain the temperature in the container at 25 ± 5 ° C. (room temperature), and stored for 18 days. The composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured in the same manner as in Example 11 and found to be 111,000, and the positive electrode material composition (A). The molecular weight reduction rate to the initial weight average molecular weight 124,000 of the polymer contained was 10.5%.

[Example 1 1 3]

Place the positive electrode material composition (B) in a sealable container (volume 30 OmL) equipped with a thermometer, a gas inlet with a valve and a gas outlet, and a lid, close the lid, and open the valves for the gas inlet and outlet. In this condition, nitrogen gas is introduced into the vessel from the inlet at a flow rate of 1 O OmL Z minutes for 3.5 minutes to replace the air in the vessel with nitrogen gas, and then the gas outlet valve is closed immediately and then the inlet Closed the container and sealed the container. Then, the container was placed in a thermostat so as to maintain the temperature in the container at 25 ± 5 ° C. (room temperature), and stored for 18 B. Thereafter, in the same manner as in Example 1-1, the composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured, to be 119,000. Cathode Material Composition (B) The molecular weight reduction rate with respect to the initial weight average molecular weight of 124,000 of the polymer in was 4.0%.

The weight average molecular weight of the polymer in the composition when stored for 3 days was measured to be 123,000, and the percentage reduction in molecular weight relative to the initial weight average molecular weight 124,000 of the polymer in the positive electrode material composition (B) Was 0.8%.

[Example 1 1 4]

The positive electrode material composition (B) was stored in the same manner as in Example 1-3 except that nitrogen gas was changed to argon gas. Thereafter, in the same manner as in Example 11, the composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured, and it was 123,000, and the positive electrode material composition (B) The molecular weight reduction rate was 0.8% with respect to the initial weight-average molecular weight of 124,000 of the polymer contained therein.

In addition, when the weight average molecular weight of the polymer in the composition when stored for 3 days and 16 days was measured, it was 124,000 in each case, and the initial weight of the polymer in the positive electrode material composition (B) was measured. The rate of decrease in molecular weight relative to the average molecular weight of 124,000 was all at 0. 0%.

[Comparative example 1 1 2]

Place the positive electrode material composition (B) in a sealable container (volume 300 mL) equipped with a thermometer and a lid, close the lid, and immediately seal the container without replacing the inside of the container with nitrogen gas (at this time, The water content of the air in the container was about 6000 ppm), the container was placed in a thermostat so that the temperature in the container was maintained at 25 ± 5 ° C. (room temperature), and stored for 16. days did. Thereafter, in the same manner as in Example 11, the composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured to be 98,000. In the positive electrode material composition (B) The molecular weight reduction rate was 21.0% relative to the initial weight average molecular weight of 124,000 of the polymer.

[Comparative Example 1 1 3]

The positive electrode material composition (B) was stored in the same manner as Comparative Example 1-2 except that the storage period was changed from 16 days to 9 days. Thereafter, the composition in the container was immediately analyzed in the same manner as in Example 1-1, and the weight average molecular weight of the polymer in the composition was measured to be 104,000, and it was found in the positive electrode material composition (B). The rate of decrease in molecular weight relative to the initial weight average molecular weight of 124,000 of the polymer was 16.1%.

[Example 1 1 5]

The positive electrode material composition (A) was stored in the same manner as in Example 11 except that nitrogen gas was changed to dry air with a dew point of 50 ° C. (content of water content: 39 ppm). Thereafter, in the same manner as in Example 11, the composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured, to be 118, 000, and the positive electrode material composition (A) The molecular weight reduction rate was 4.8% with respect to the initial weight-average molecular weight of 124,000 of the polymer contained therein.

[Example 2-1]

The positive electrode material composition (A) is placed in a sealable container (volume 300 mL) equipped with a thermometer and a lid and the lid is closed, and the container is closed (at this time, the amount of ice contained in the container is about ice) 3000 The container was put in a thermostat so that the temperature in the container was maintained at 0 to 5 ° C., and stored for 18 days. Thereafter, in the same manner as in Example 11, the composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured, and it was 123,000. The molecular weight reduction rate was 0.8% with respect to the initial weight average molecular weight of 124,000 of the polymer in.

[Example 2-2]

Place the positive electrode material composition (A) in a sealable container (volume 300 mL) equipped with a thermometer and a lid, close the lid, and dry air at a dew point of 50 ° C in the container (water content: 39 ppm) After filling the container with a flow rate of 100 mL for 3.5 minutes and completely replacing the air in the container with dry air (at this time, the water content of the air in the container was about 130 ppm), immediately The container was sealed, and the container was placed in a thermostat so that the temperature in the container was maintained at 0 to 5 ° C., and stored for 18 days. Thereafter, in the same manner as in Example 1_1, the composition in the container was immediately analyzed, and the weight average molecular weight of the polymer in the composition was measured to be 122,000. The polymer in the positive electrode material composition (A) The molecular weight reduction rate to an initial weight average molecular weight of 120,000 was 1.6%.

[Example 2-3]

The positive electrode material composition (B) is placed in a sealable container (volume 300 mL) equipped with a thermometer and a lid, the lid is closed, and the container is closed (at this time, the moisture content of the air in the container is about The container was placed in a thermostat so that the temperature in the container was maintained at 0-5 ° C., and stored for 18 days. Thereafter, the composition in the container was immediately analyzed and the weight average molecular weight of the polymer in the composition was measured in the same manner as in Example 11 and found to be 118, 000. The positive electrode material composition (B) The decrease in molecular weight was 4.8% relative to the initial weight-average molecular weight of 124,00 ° of the polymer contained therein.

Production Example 3 Preparation of Particulate Positive Electrode Material Composition (Α ′) Containing Electrolyte Salt

In the same manner as in Production Example 1, square shaped pellets before drying were obtained, charged into a grinder ("U-480 type" manufactured by Horai Co., Ltd.) and crushed, and 1.00 to 3.34 mm mesh The particle size was 80% on. The particulate matter is placed in a conical dryer ("Vacuum tumble dryer" manufactured by Nisso Industries Co., Ltd.), and nitrogen is allowed to flow at a flow rate of 5 L / min. Drying was performed for 12 hours or more under the conditions of rr to obtain a particulate positive electrode material composition (Α ′).

[Example 3-1]

In a plastic bag with a chuck, 390 g of the positive electrode material composition (A ') and silica particles (“Aerosil R 972” manufactured by Nippon Aerosil Co., Ltd .: particle diameter about 16 nm, specific surface area of particles (BET method) 1 1 OmVg) 1. Add 95 g and shake well for up to 5 minutes to mix the positive electrode material composition (A,) particles with the silica particles, and mix the positive electrode material composition (粒子 ') particles with the silica particles. Obtained.

Put together with the above-mentioned mixture in a sealable glove box, put in place what is necessary for the subsequent operation such as Tendon, a cylindrical container, a plastic bag with a chuck, a weight etc. It was circulated for 4 days so that the dew point of the air in the glove box would be 40 ° C (water content: 127 ppm). In the glove box, weigh 68.5 g of the mixture in a cylindrical container (volume 12 QmL, inner diameter 5 cm), and place 200 g of cylindrical weights (inner diameter 4.9 cm) on the mixture. Immediately after placing the weight, turn the weight upside down (the weight of the weight While keeping this condition, the product was put in a plastic bag with a chuck and closed, and then taken out of the glove box and immediately heat sealed in parallel with the chuck for sealing. Next, this sealed plastic bag (the mixture placed inside is on the weight, and the weight load is not applied to the mixture) is placed in a thermostatic bath at 40 ° C for 2 hours to control the temperature. After that, the mixture inside the plastic bag and the weight are immediately inverted so that the weight is on the mixture, and the plastic bag is placed in a 40 ° C. constant temperature bath with the weight load applied to the mixture. It was stored for 9 days. Thereafter, the plastic bag was immediately opened and the positive electrode material composition was gently removed from the cylindrical container, and the state of blocking was evaluated according to the following criteria. The result was o.

:: The positive electrode material composition is completely separated

:: The positive electrode material compositions lightly adhere to each other and maintain the shape as they were in the container, but when lightly adhere, they easily separate.

X: The positive electrode material composition adheres firmly to each other and maintains its shape as it was in the container, and it does not easily come apart even if it slightly sticks

On the other hand, a mixture of the cathode material composition (Α ') particles and the silica particles described above in a sealable container (volume 300 mm) equipped with a thermometer, a gas inlet and a valve outlet, and a lid With the lid closed and with the gas inlet and outlet valves open, introduce nitrogen gas into the vessel from the inlet at a flow rate of 1 OO m LZ minutes for 3.5 minutes to make the air in the vessel nitrogen Immediately after gas replacement, the gas outlet valve was closed and the inlet valve was closed to seal the vessel. Then, the container was placed in a thermostat so that the temperature in the container was maintained at 40 ° C., and stored for 18 days. Thereafter, the composition in the container was immediately analyzed in the same manner as in Example 1_1, and the weight average molecular weight of the polymer in the composition was measured to be 1 18, 00, and the composition of the positive electrode material was The molecular weight reduction rate with respect to the initial weight average molecular weight 1 2 4 0 0 0 0 0 of the polymer in substance (Α ') was 4 8%.

[Example 3-2]

In the same manner as in Example 3-1, a mixture of positive electrode material composition (Α ') particles and silica particles was obtained.

In the sealable glove box, put together with the above-mentioned mixture, a balance, a cylindrical container, a plastic bag with a chuck, a weight, etc. necessary for the subsequent operation, and adjust the temperature in a thermostat at 20 ° C. The same procedure as in Example 3-1 was performed except that the battery was placed in a constant temperature bath at 0 ° C. and stored for 9 days, and the positive electrode material composition (Α ') was stored. Thereafter, in the same manner as in Example 3-1, the state of blocking was evaluated. The result was 〇.

On the other hand, a mixture of particles of the positive electrode material composition (A,) and silica particles described above in a sealable container (volume 300 mm) equipped with a thermometer, a gas inlet having a valve and a gas outlet, and a lid. the close the lid put, 3 nitrogen gas into the container from the conductor inlet in a state of spaced valve of the gas inlet and outlet flow rate 1 0 0 m L _/ / min. introduced in the container 5 minutes Immediately after replacing the air with nitrogen gas, the gas outlet valve was closed and the inlet valve was closed to seal the container. Then, the container was placed in a thermostat so that the temperature in the container was maintained at 20 ° C., and stored for 18 days. Thereafter, the composition in the container was immediately analyzed and the weight average molecular weight of the polymer in the composition was measured in the same manner as in Example 11 and it was 12 2 00, and the positive electrode material was obtained. Composition (A, The molecular weight reduction rate to the initial weight average molecular weight of 1,204, 0 0 0 of the polymer in b) was 1.6%.

[Example 3-3]

Put together with the above-mentioned mixture, in the sealable glove box, the items required for the subsequent operation such as Tendon, cylindrical container, plastic bag with chuck, weight, etc. From this point on, carry out the operation of circulating nitrogen gas in the glove box. Do not do this (at this time, the amount of moisture contained in the air in the glove box was about 100 ppm), and the temperature in 0 to 5 ° C and the temperature in 0 to 5 ° C. The same procedure as in Example 3-1 was carried out except that the inside was changed to storage for 9 days, and the state of blocking was evaluated. The result was 〇.

On the other hand, the mixture of the positive electrode material composition (Α ′) particles and the silica particles described above is put into a sealable container (volume 300 mm) equipped with a thermometer and a lid, the lid is closed, and the container is sealed. After that (at this time, the moisture content of the air in the container was about 100 ppm), the container was placed in a thermostat so that the temperature in the container was maintained at 0 to 5 ° C. It was stored for 18 days. Thereafter, the composition in the container was immediately analyzed in the same manner as in Example 1-1, and the weight average molecular weight of the polymer in the composition was measured. The molecular weight reduction rate with respect to the initial weight average molecular weight of the polymer in the substance (Α ') was 1024%.

[Example 3-4] '

Using only the positive electrode material composition (Α ′) instead of the mixture of the positive electrode material composition (Α ′) particles and the silica particles (in a glove box, the positive electrode material composition (Α ′) 68.5 g) was changed to weighing), and that the temperature was controlled in a constant temperature bath at 23.degree. C., and it was put in a constant temperature bath at 23.degree. C. and stored for eight days. The state of blocking was evaluated in the same manner as in 3-1. The result was X.

[Example 3-5]

In Example 3-4, the positive electrode was prepared in the same manner as in Example 3-4, except that the temperature was controlled in a thermostat of 13.degree. C., and then stored in a thermostat of 13.degree. C. for 8 days. The material composition (Α ') was saved. Thereafter, in the same manner as in Example 3-1, the state of blocking was evaluated. The result was 〜 ~> <.

[Example 3-6]

In Example 3-4, the operation of circulating nitrogen gas in the glove box was not performed (at this time, the water content of the air in the glove box was about 150 ppm), and The positive electrode material composition (Α ′) was prepared in the same manner as in Example 3-4 except that the temperature was controlled in a thermostat of 5 ° C., and stored in a thermostat of 0 to 5 ° C. and stored for 8 days. Saved. Thereafter, in the same manner as in Example 3-1, the state of blocking was evaluated. The result was Δ.

[Example 3-7]

Example 3-6 In the same manner as in Example 3-6 except that the temperature was controlled in a thermostat at 110 ° C., and the temperature was changed to storage for 10 days in a thermostat at 110 ° C. , The positive electrode material composition (A,) was stored. Thereafter, in the same manner as in Example 3-1, the state of blocking was evaluated. The result was △. Above example · Table 1 summarizes the results for the comparative example,

【table 1】

The positive electrode material compositions (A) and (Α ′) of the positive electrode material compositions stored in each of the above Examples and Comparative Examples are used as they are as lithium salt in the positive electrode material composition (Β) as an electrolyte salt. A cathode was prepared by adding a methanemethane) imide (L i N (CF ₃ S 0 ₂ ) ₂ ) so that the amount of the electrolyte salt was 7% by weight in the composition (B), and forming immediately. Then, a lithium battery is produced using the positive electrode, and the performance of the obtained battery (short test and And all the batteries based on the positive electrode material composition stored in each example exhibited better performance than the batteries based on the positive electrode material composition stored in each comparative example. It is hot. Industrial applicability

The method of storing a positive electrode material composition of a lithium secondary battery according to the present invention can be used when transporting or storing a material for producing a positive electrode used for a lithium secondary battery.

Claims

The scope of the claims

1. A method for storing a positive electrode material composition, which essentially comprises a polymer, an electrode active material and a conductive auxiliary, wherein Mw is the weight average molecular weight of the polymer in the composition before storage. When the weight average molecular weight of the polymer in the composition when stored for 18 days is Mw, the reduction rate (D _Mw ) of the weight average molecular weight represented by the following formula (1) is 10% or less A method of storing a positive electrode material composition for a lithium secondary battery, characterized in that

D _Mw (%) = [(Mw.-Mw) / Mw ₀ XI 00 (1)

2. A method of storing a positive electrode material composition which essentially comprises a polymer, an electrode active material and a conductive auxiliary, wherein the temperature is controlled to 50 ° C. or less under an inert gas atmosphere. The preservation | save method of the positive electrode material composition for batteries.

3. A method for storing a positive electrode material composition, which essentially comprises a polymer, an electrode active material and a conductive support agent, comprising controlling the temperature to 5 ° C. or less in an air atmosphere, and characterized in that it is positive for lithium secondary batteries. Method of storage of polar material composition.

4. The lithium secondary according to any one of claims 1 to 3, wherein the composition is a solidified material, and the solidified materials do not adhere to each other to form a lump, even if a plurality of the compositions are stored. A method of storing a positive electrode material composition for a battery.

5. The method for storing a positive electrode material composition for a lithium secondary battery according to claim 4, wherein fine particles are added.

6. The electrode active material is L i x V y O z (where x, y and z are each independent of each other and 0 x 2 y = (mx + 2 z) Zn, and z = (mx + ny) A real number satisfying / 2 (however, m is a valence number of Li and n is a valence number of V and is a real number of 4 or more)). The storage method of the positive electrode material composition for lithium secondary batteries as described in any of the above.

7. The method for storing a positive electrode material composition for a lithium secondary battery according to any one of claims 1 to 6, wherein the polymer is an ionically conductive polyether polymer.