JP2017117576A - Binder composition for nonaqueous electrolyte battery, binder aqueous solution for nonaqueous electrolyte battery, slurry composition for nonaqueous electrolyte battery, nonaqueous electrolyte battery negative electrode and nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a binder composition for a nonaqueous electrolyte battery, which can achieve a high electrode density because of a low swelling property of a resin to an electrolytic solution, thereby enhancing battery characteristics.SOLUTION: Provided are a binder aqueous solution for a nonaqueous electrolyte battery, a slurry composition for a nonaqueous electrolyte battery, a nonaqueous electrolyte battery negative electrode arranged by use thereof, a nonaqueous electrolyte battery, etc. The binder aqueous solution comprises a neutralized salt of an α-olefin-maleic acid copolymer resulting from the copolymerization of α-olefin and maleic acid, of which the swelling rate to an electrolytic solution is 1.0-1.1.SELECTED DRAWING: None

Description

  The present invention relates to a binder composition for a non-aqueous electrolyte battery, a binder aqueous solution, a slurry composition, a non-aqueous electrolyte battery negative electrode, and a non-aqueous electrolyte battery.

  In recent years, mobile terminals such as mobile phones, notebook computers, and pad-type information terminal devices have been widely used. Non-aqueous electrolyte batteries are frequently used as secondary batteries used as power sources for these portable terminals. Since portable terminals are required to have more comfortable portability, miniaturization, thinning, weight reduction, and high performance have rapidly progressed, and have come to be used in various places. This trend continues today, and batteries used in mobile terminals are further required to be smaller, thinner, lighter, and higher in performance.

  Secondary batteries used in small portable terminals are required to have a high capacity and a more compact battery, which reduces the internal resistance of the battery and increases the energy density per volume as well as the energy density per mass. Is required. Since battery capacity is affected by the amount of active material, to increase the active material in a limited space called a battery, encapsulate as much active material as possible by increasing the electrode density. It is effective to increase the energy density per volume.

A non-aqueous electrolyte battery has a positive electrode and a negative electrode installed via a separator, and LiPF ₆ , LiBF ₄ , LiTFSI (lithium (bistrifluoromethylsulfonylimide)), LiFSI (lithium (bisfluorosulfonylimide)) and other lithium It has a structure in which a salt is stored in a container together with an electrolytic solution in which a salt is dissolved in an organic liquid such as ethylene carbonate.

  The negative electrode and the positive electrode are usually obtained by dissolving or dispersing a binder and a thickener in water and mixing an active material, a conductive aid (conductivity imparting agent) and the like with this, Hereinafter, it may be simply formed as a mixed layer by coating the current collector on the current collector and drying the water.

For example, the negative electrode is composed of a carbonaceous material that can store and release lithium ions, which is an active material, a metal-containing oxide such as silicon or tin, and, if necessary, acetylene black as a conductive additive, and a current collector such as copper. The battery is bonded to the body with a binder for secondary battery electrodes. On the other hand, for the positive electrode, LiCoO ₂ that is an active material and, if necessary, a conductive aid similar to that of the negative electrode are bound to a current collector such as aluminum using a secondary battery electrode binder. Is.

  Up to now, diene rubbers such as styrene-butadiene rubber, acrylics such as polyacrylic acid, and polyimides have been used as binders for aqueous media (for example, Patent Documents 1, 2, and 3). Examples of the thickener include methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropoxycellulose, carboxymethylcellulose sodium salt (CMC-Na), sodium polyacrylate, etc. Among them, CMC-Na is often used. (For example, patent document 4).

  However, diene rubber such as styrene-butadiene rubber has a problem that the resin density is high and the electrode density cannot be increased unless it is rolled at a high pressure during electrode rolling. Even if a high electrode density is obtained, since the rolling is performed at a high pressure, the active material is greatly deformed, causing a reduction in battery capacity. Further, when a metal oxide having a large discharge capacity is used as an active material, the volume change accompanying the insertion / release of lithium ions is very large, and the expansion / contraction is repeated with the charge / discharge cycle. Therefore, when styrene-butadiene rubber or the like is used as a binder, there is a drawback that cycle deterioration is likely to occur due to the active material being detached from the binder or separated from the collector electrode. Acrylic and polyimide systems have lower swellability to electrolytes than styrene-butadiene rubber systems and exhibit relatively high electrode density under low rolling conditions, but especially when metal oxides are used as the active material In such a case, there is a problem that electric resistance is high.

  Recently, demands such as extension of the usage time of mobile terminals have increased, and the above issues are particularly urgently required to increase the battery capacity (high density, low resistance) and improve the life (cycle characteristics). Until now, it has been difficult to improve battery characteristics such as cycle characteristics and battery capacity while maintaining high electrode density and low resistance.

JP 2000-67917 A JP 2008-288214 A JP 2011-142068 A Japanese Patent Application Laid-Open No. 2014-13693

  The present invention has been made in view of the above-described problems, and provides a binder composition for a non-aqueous electrolyte battery that has a low swelling property of a resin into an electrolyte solution and can obtain a high electrode density. The purpose is to improve.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have found that the above object is achieved by using a negative electrode for a non-aqueous electrolyte battery having the following configuration, and further studies are made based on this knowledge. This completes the present invention.

  That is, the composition of a binder for a nonaqueous electrolyte battery (hereinafter also simply referred to as a binder composition) according to one aspect of the present invention is an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and a maleic acid. It is characterized by containing a neutralized salt of the polymer and having a swelling ratio of 1.0 or more and 1.1 or less in the electrolytic solution.

  With such a configuration, it is considered that an electrode having a high electrode density can be produced and battery characteristics can be improved. Moreover, it is possible to obtain a high-density electrode without increasing the pressure during rolling, and as a result, it is possible to suppress the deformation of the active material more than necessary, and to maximize the performance of the active material itself, It is considered that battery characteristics can be improved.

  Furthermore, by using a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerization of the α-olefin and maleic acid as a binder, ion transfer in the electrolyte solution and on the active material surface becomes smooth and electric. It is thought that the resistance can be lowered.

  Moreover, the binder aqueous solution for non-aqueous electrolyte batteries which concerns on the other situation of this invention consists of the said binder composition and water, It is characterized by the above-mentioned.

  A slurry composition for a non-aqueous electrolyte battery according to still another aspect of the present invention includes the binder composition, an active material, and a solvent.

  A nonaqueous electrolyte battery negative electrode according to still another aspect of the present invention is characterized in that a current collector is bound with a mixed layer containing at least the binder composition for a nonaqueous electrolyte battery and an active material. And

  A nonaqueous electrolyte battery according to still another aspect of the present invention includes the above nonaqueous electrolyte battery negative electrode, a positive electrode, and an electrolytic solution.

  ADVANTAGE OF THE INVENTION According to this invention, the binder composition for nonaqueous electrolyte batteries which is high electrode density and low resistance can be obtained, and also the improvement of the battery characteristic of a nonaqueous electrolyte battery can be implement | achieved using it.

  Hereinafter, although embodiment of this invention is described in detail, this invention is not limited to these.

  The binder composition for nonaqueous electrolyte batteries of the present embodiment (hereinafter also simply referred to as a binder composition) is a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing α-olefins and maleic acids. And the swelling ratio to the electrolytic solution is 1.0 or more and 1.1 or less.

  In the present embodiment, an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid is composed of a unit based on the α-olefin (A) and a unit based on the maleic acid (B). The components (A) and (B) preferably satisfy (A) / (B) = 1/1 to 1/3 (molar ratio). Moreover, it is preferable that it is a linear random copolymer whose weight average molecular weight is 10,000-700,000.

In this embodiment, the unit (A) based on α-olefins is represented by the general formula —CH ₂ CR ¹ R ² — (wherein R ¹ and R ² may be the same or different from each other, hydrogen Represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group, an aryl group, or an ether group. The α-olefin used in the present embodiment is a linear or branched olefin having a carbon-carbon unsaturated double bond at the α-position. In particular, olefins having 2 to 12 carbon atoms, particularly 2 to 8 carbon atoms are preferred. Representative examples that may be used include ethylene, propylene, n-butylene, isobutylene, n-pentene, isoprene, 2-methyl-1-butene, 3-methyl-1-butene, n-hexene, 2-methyl- 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-butene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethylbutadiene, 2,5 -Pentadiene, 1,4-hexadiene, 2,2,4-trimethyl-1-pentene, methyl vinyl ether, styrene and the like. Among these, isobutylene is particularly preferable from the viewpoints of availability, polysynthesis, and product stability. Here, the isobutylene includes a mixture containing isobutylene as a main component, for example, a BB fraction (C4 fraction). These olefins may be used alone or in combination of two or more.

  In the present embodiment, maleic anhydride, maleic acid, maleic acid monoester (for example, methyl maleate, ethyl maleate, propyl maleate, phenyl maleate, etc.), maleic acid, as the unit (B) based on maleic acids Maleic anhydride derivatives such as diesters (eg, dimethyl maleate, diethyl maleate, dipropyl maleate, diphenyl maleate, etc.), maleic imides or N-substituted derivatives thereof (eg maleic imide, N-methylmaleimide, N N-substituted alkylmaleimide such as ethylmaleimide, N-propylmaleimide, Nn-butylmaleimide, Nt-butylmaleimide, N-cyclohexylmaleimide, N-methylphenylmaleimide, N-ethyl Phenyl male N-substituted alkylphenylmaleimide such as N-substituted alkoxyphenylmaleimide such as N-methoxyphenylmaleimide and N-ethoxyphenylmaleimide), and further halides thereof (for example, N-chlorophenyl) Maleimide), citraconic anhydride, citraconic acid, citraconic acid monoester (eg, methyl citraconic acid, ethyl citraconic acid, propyl citraconic acid, phenyl citraconic acid, etc.), citraconic acid diester (eg, dimethyl citraconic acid, diethyl citraconic acid, citraconic acid) Citraconic anhydride derivatives such as dipropyl acid, diphenyl citraconic acid, etc., citraconic acid imide or N-substituted derivatives thereof (eg citraconic acid imide, 2-methyl-N-methylmaleimide, 2-methyl-N-ethylmaleic acid) N-substituted alkylmaleimides such as 2-methyl-N-propylmaleimide, 2-methyl-Nn-butylmaleimide, 2-methyl-Nt-butylmaleimide, 2-methyl-N-cyclohexylmaleimide 2-methyl-N-substituted alkylphenylmaleimide such as methyl-N-phenylmaleimide, 2-methyl-N-methylphenylmaleimide, 2-methyl-N-ethylphenylmaleimide, or 2-methyl-N- Methoxyphenylmaleimide, 2-methyl-N-substituted alkoxyphenylmaleimide such as 2-methyl-N-ethoxyphenylmaleimide), and further halides thereof (for example, 2-methyl-N-chlorophenylmaleimide) Is preferred. Among these, use of maleic anhydride is preferable from the viewpoint of availability, polymerization rate, and ease of molecular weight adjustment. These maleic acids may be used alone or in combination.

As for the content rate of each said structural unit in the copolymer of this embodiment, it is desirable for (A) / (B) to exist in the range of 1 / 1-1 / 3 by molar ratio. This is because the advantages of hydrophilicity, water solubility, and affinity for metals and ions as a high molecular weight substance that dissolves in water can be obtained. In particular, the molar ratio of (A) / (B) is desirably 1/1 or a value close thereto, in which case the unit based on α-olefin, that is, —CH ₂ CR ¹ R ² — A copolymer having a structure in which the units shown and units based on maleic acids are alternately repeated is obtained.

  The mixing ratio of α-olefins and maleic acids for obtaining the copolymer of the present embodiment varies depending on the composition of the target copolymer, but α- 1 to 3 times the number of moles of maleic acids. Use of olefin is effective for increasing the reaction rate of maleic acids.

  The method for producing the copolymer of the present embodiment is not particularly limited, and for example, the copolymer can be obtained by radical polymerization. In this case, the polymerization catalyst used is an azo catalyst such as azobisisobutyronitrile, 1,1-azobiscyclohexane-1-carbonitrile, or an organic peroxide catalyst such as benzoyl peroxide or dicumyl peroxide. preferable. The amount of the polymerization catalyst used is required to be in the range of 0.1 to 5 mol% with respect to maleic acids, but is preferably 0.5 to 3 mol%. As a method for adding the polymerization catalyst and the monomer, they may be added all at the beginning of the polymerization, but it is desirable to add them sequentially as the polymerization proceeds.

In the method for producing a copolymer of this embodiment, the molecular weight can be appropriately adjusted mainly depending on the monomer concentration, the amount of catalyst used, and the polymerization temperature. For example, as a substance for reducing the molecular weight, a metal salt of Group I, II or III of the periodic table, a hydroxide, a halide of a Group IV metal, a general formula N≡, HN =, H ₂ N— or H It is also possible to adjust the molecular weight of the copolymer by adding an amine represented by ₄ N-, a nitrogen compound such as ammonium acetate or urea, or a mercaptan during the polymerization or during the polymerization. The polymerization temperature is preferably 40 ° C to 150 ° C, more preferably 60 ° C to 120 ° C. If the polymerization temperature is too high, the resulting copolymer tends to be in a block form, and the polymerization pressure may be significantly increased. The polymerization time is usually preferably about 1 to 24 hours, more preferably 2 to 10 hours. The amount of the polymerization solvent used is preferably adjusted so that the concentration of the obtained copolymer is 5 to 40% by weight, more preferably 10 to 30% by weight.

  As described above, it is preferable that the copolymer of the present embodiment usually has a weight average molecular weight of 10,000 to 700,000. A more preferred weight average molecular weight is 15,000 to 650,000. When the weight average molecular weight of the copolymer of this embodiment is less than 10,000, the crystallinity is high and the binding strength between particles may be low. On the other hand, when it exceeds 700,000, the solubility in water or a solvent becomes small, and it may precipitate easily.

  The weight average molecular weight of the copolymer of this embodiment can be measured by, for example, a light scattering method or a viscosity method. When the intrinsic viscosity ([η]) in dimethylformamide is measured using the viscosity method, the copolymer of the present embodiment preferably has an intrinsic viscosity in the range of 0.01 to 1.7. The copolymer of the present embodiment is usually obtained in the form of a powder having a grain size of about 16 to 60 mesh.

  In the present embodiment, the neutralized salt of the copolymer means that the active hydrogen of carbonyl acid generated from maleic acid reacts with a basic substance to form a salt to become a neutralized salt. Is preferred. In the neutralized salt of the α-olefin-maleic acid copolymer used in the present embodiment, a basic substance containing a monovalent metal and / or ammonia is used as the basic substance from the viewpoint of binding properties as a binder. Is preferably used.

  In the present embodiment, the amount of the basic substance containing monovalent metal and / or ammonia is not particularly limited and is appropriately selected depending on the purpose of use and the like, but usually in the maleic acid copolymer. The amount is preferably 0.6 to 2.0 mol per mol of maleic acid unit. If it is such usage-amount, it will be possible to adjust the neutralization degree of the binder composition of this embodiment to a predetermined range. In addition, when the usage-amount of the basic substance containing a monovalent metal is made into 0.8-2.0 mol amount per 1 mol of maleic acid units in a maleic acid copolymer preferably, there is little alkali residue and it is water-soluble. The copolymer salt can be obtained.

  The reaction of the α-olefin-maleic acid copolymer with the basic substance containing monovalent metal and / or ammonia can be carried out according to a conventional method, but is carried out in the presence of water, and the α-olefin-maleic acid is obtained. A method of obtaining the neutralized salt of the copolymer as an aqueous solution is simple and preferable.

  Examples of basic substances containing monovalent metals that can be used in the present embodiment include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and lithium hydroxide; alkali metals such as sodium carbonate and potassium carbonate. Carbonates of alkali metals such as sodium acetate and potassium acetate; phosphates of alkali metals such as trisodium phosphate, and the like. Among these, ammonia, lithium hydroxide, sodium hydroxide, and potassium hydroxide are preferable. In particular, it is preferable to use ammonia or lithium hydroxide as the binder for the nonaqueous electrolyte battery. The basic substance containing monovalent metal and / or ammonia may be used alone or in combination of two or more. In addition, a neutral salt of an α-olefin-maleic acid copolymer is used in combination with a basic substance containing an alkali metal hydroxide such as sodium hydroxide as long as it does not adversely affect battery performance. May be prepared.

The binder composition of this embodiment has a swelling ratio to the electrolytic solution of 1.0 or more and 1.1 or less. In the present embodiment, the swelling rate is a value obtained by the following formula when the dry mass of the binder composition is Wd and the mass after being immersed in an electrolyte (described later) for 1 week is Ww (swelled mass). It is.
Swelling rate = Ww / Wd

  It is considered that when the swelling ratio is 1.0 or more and 1.1 or less, an electrode having a high electrode density can be produced and battery characteristics can be improved. Moreover, it is possible to obtain a high-density electrode without increasing the pressure during rolling, and as a result, it is possible to suppress the deformation of the active material more than necessary, and to maximize the performance of the active material itself, It is considered that battery characteristics can be improved.

  Next, in this embodiment, 0.3-1 mol is preferable with respect to 1 mol of carboxylic acids produced | generated from maleic acids in the said copolymer of the said binder composition. If it is less than 0.3, the solubility in water or a solvent becomes small, and it easily precipitates, making slurry coating difficult. More preferably, the neutralization degree is in the range of 0.4 to 1.0. Thereby, the slurry composition which was excellent in applicability | paintability can be obtained. Furthermore, in terms of battery capacity, the neutralization degree is desirably 0.4 or more and less than 1.0.

  In the present embodiment, the degree of neutralization can be measured using a method such as titration with a base, infrared spectrum, NMR spectrum, etc. In order to measure the neutralization point simply and accurately, titration with a base is used. Preferably it is done. The specific titration method is not particularly limited, but it can be dissolved in water with little impurities such as ion-exchanged water, and a basic substance such as lithium hydroxide, sodium hydroxide, potassium hydroxide, It can be carried out by neutralization. The indicator for the neutralization point is not particularly limited, but an indicator such as phenolphthalein indicating pH with a base, and a PH meter can be used.

  In this embodiment, the neutralization degree of the binder composition may be adjusted, for example, by adjusting the neutralization degree of the binder composition, or the neutralization degree of the aqueous solution in which the binder composition is dissolved is directly adjusted. You may adjust. Specifically, for example, the degree of neutralization is adjusted by adjusting the addition amount of a basic substance (ammonia, lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.) containing a monovalent metal as described above. Although it is possible to adjust to the said range, it is not limited to it. Specifically, as described above, the basic substance containing monovalent metal and / or ammonia is preferably added in an amount of 0.6 to 2.0 mol per mol of maleic acid unit in the maleic acid copolymer. Can be adjusted to the above range. More preferably, the basic substance containing a monovalent metal and / or ammonia is added more reliably by adding 0.8 to 2.0 moles per mole of maleic acid units in the maleic acid copolymer. It is possible to adjust to the above range.

  Next, in this embodiment, the ring-opening rate of the copolymer represents the hydrolysis rate of the maleic anhydride sites that polymerize with α-olefins when maleic anhydride is used as the maleic acid. In the copolymer of the present embodiment, a preferable ring opening rate is 60 to 100%, more preferably 70% to 100%, and still more preferably 80 to 100%. When the ring-opening rate is too low, the structural freedom of the copolymer becomes small and the stretchability becomes poor, so that the force for adhering adjacent electrode material particles may be reduced, which is not preferable. Furthermore, there is a possibility that problems such as low affinity for water and poor solubility may occur. The ring-opening rate can be determined, for example, by measuring the hydrogen at the α-position of maleic acid opened by 1H-NMR with reference to the hydrogen at the α-position of maleic anhydride. The ratio of the carbonyl group derived from the carbonyl group and the ring-opened maleic anhydride can also be determined by IR measurement.

  In this embodiment, when the maleic acid is maleic anhydride, the neutralized salt of the copolymer means that the active hydrogen of the carbonyl acid generated by the ring opening of maleic anhydride is a basic substance as described above. It forms a salt by forming a salt. The degree of neutralization in this case is not particularly limited. However, when used as a binder, in consideration of reactivity with the electrolytic solution, usually with respect to 1 mol of carbonyl acid generated by ring opening, A range of 0.5 to 1 mol is preferable, and a neutralized range of 0.6 to 1 mol is more preferable. Such a neutralization degree has the advantage of low acidity and suppression of electrolyte decomposition. Furthermore, it is desirable that it is less than 0.6-1 mol in terms of battery capacity. The degree of neutralization of the copolymer when maleic anhydride is used can be measured by the same method as described above.

  The binder composition of the present embodiment is usually used as a binder aqueous solution for a non-aqueous electrolyte battery comprising the above-described binder composition and water.

  In addition, the nonaqueous electrolyte battery binder composition of the present embodiment is usually a nonaqueous electrolyte battery slurry composition (hereinafter simply referred to as slurry), which further contains an active material and water in addition to the above-described binder composition. It is preferably used as a composition).

  Further, in the present embodiment, the nonaqueous electrolyte battery negative electrode is formed by binding a current collector to a mixed layer containing at least the binder composition for a nonaqueous electrolyte battery of the present embodiment and a negative electrode active material. . This negative electrode can be formed by applying the slurry composition for a non-aqueous electrolyte battery negative electrode to a current collector and then removing the solvent by a method such as drying. If necessary, a thickener, a conductive aid and the like can be added to the mixed layer.

  In the slurry composition for a non-aqueous electrolyte battery, the amount of the neutralized salt of the α-olefin-maleic acid copolymer used relative to 100 parts by weight of the active material is usually preferably 0.1 to 4 parts by weight. More preferably, it is 0.3-3 weight part, More preferably, it is 0.5-2 weight part. If the amount of copolymer is too small, the viscosity of the slurry for nonaqueous electrolyte batteries may be too low and the thickness of the mixed layer may be reduced. Conversely, if the amount of copolymer is too large, the discharge capacity may decrease. There is sex.

  On the other hand, the amount of the solvent in the slurry composition is usually preferably 40 to 150 parts by weight, more preferably 70 to 130 parts by weight with respect to 100 parts by weight of the active material.

  Examples of the solvent in the slurry composition for a non-aqueous electrolyte battery according to this embodiment include, in addition to the above water, alcohols such as methanol, ethanol, propanol, and 2-propanol, and cyclic ethers such as tetrahydrofuran and 1,4-dioxane. N, N-dimethylformamide, amides such as N, N-dimethylacetamide, cyclic amides such as N-methylpyrrolidone and N-ethylpyrrolidone, sulfoxides such as dimethylsulfoxide, and the like can also be used. In these, use of water is preferable from a viewpoint of safety.

  Further, in addition to water as the solvent in the slurry composition of the present embodiment, the following organic solvent may be used in combination within a range of preferably 20% by weight or less of the entire solvent. As such an organic solvent, those having a boiling point of 100 ° C. or more and 300 ° C. or less at normal pressure are preferable, for example, hydrocarbons such as n-dodecane; alcohols such as 2-ethyl-1-hexanol and 1-nonanol. Esters such as γ-butyrolactone and methyl lactate; amides such as N-methylpyrrolidone, N, N-dimethylacetamide and dimethylformamide; organic dispersion media such as sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane.

When the slurry composition of the present embodiment is used for a negative electrode, examples of the negative electrode active material (sometimes abbreviated as active material) added to the negative electrode slurry composition include amorphous carbon, graphite, natural graphite, Carbonaceous materials such as mesocarbon microbeads (MCMB), pitch-based carbon fiber, carbon black, activated carbon, carbon fiber, hard carbon, soft carbon, mesoporous carbon, polyacene and other conductive polymers, expressed as SiOx, SnOx, LiTiOx Examples include composite metal oxides and other metal oxides, lithium metals such as lithium metals and lithium alloys, metal compounds such as TiS ₂ and LiTiS ₂ , and composite materials of metal oxides and carbonaceous materials. The

  In this embodiment, an additive capable of imparting viscosity, toughness, adhesiveness and the like to the binder composition can be added to the slurry composition as necessary. Additives that can be added are not particularly limited, and various alcohols, in particular, polyvinyl alcohol and modified products thereof, polysaccharides such as celluloses and starches, polyethers such as polyethylene glycol and polypropylene glycol, and polyamines. , Polyvinyl alcohols, pyrrolidones, maleic acids, and the like can be used.

  The amount of the thickener used in the slurry composition as needed is preferably about 0.1 to 4 parts by weight, more preferably 0.3 to 3 parts by weight with respect to 100 parts of the negative electrode active material. More preferably, it is 0.5 to 2 parts by weight. If the amount of the thickener is excessively small, the viscosity of the slurry may be too low and the thickness of the mixed layer may be reduced. Conversely, if the amount of the thickener is excessively large, the discharge capacity may be decreased.

  Moreover, as a conductive support agent mix | blended with a slurry composition as needed, metal powder, a conductive polymer, acetylene black, carbon black etc. are mentioned, for example. The amount of the conductive aid used is usually preferably 0.3 to 10 parts by weight, more preferably 0.5 to 7 parts by weight with respect to 100 parts by weight of the active material.

  The current collector used for the nonaqueous electrolyte battery negative electrode of the present embodiment is not particularly limited as long as it is made of a conductive material. For example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold Metal materials such as platinum can be used. One of these may be used alone, or two or more of these may be used in combination at any ratio.

  In particular, when copper is used as the negative electrode current collector, the effect of the slurry for nonaqueous electrolyte batteries of the present invention is most apparent. The shape of the current collector is not particularly limited, but usually a sheet shape having a thickness of about 0.001 to 0.5 mm is preferable.

  The method for applying the nonaqueous electrolyte battery slurry to the current collector is not particularly limited. Examples thereof include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a dipping method, and a brush coating method. The amount to be applied is not particularly limited, but the thickness of the mixed layer containing the active material, conductive additive, binder and thickener formed after removing the solvent or dispersion medium by a method such as drying is preferably 0.005 to 0.005. An amount of 5 mm, more preferably 0.01 to 2 mm is common.

  Examples of the electrode rolling method include a die press and a roll press, and the press pressure is preferably 1 to 40 MPa. If the pressing pressure is too low, a desired electrode density cannot be obtained. If the pressing pressure is too high, the active material may be greatly deformed or cracked, which may reduce the initial battery capacity.

  Furthermore, the present invention also includes a non-aqueous electrolyte battery including the above non-aqueous electrolyte battery negative electrode, a positive electrode, and an electrolytic solution.

In the present embodiment, as the positive electrode, a positive electrode usually used for a nonaqueous electrolyte battery is used without any particular limitation. For example, as the positive electrode active material, TiS ₂ , TiS ₃ , amorphous MoS ₃ , Cu ₂ V ₂ O ₃ , amorphous V ₂ O—P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O Transition metal oxides such as ₁₃ and lithium-containing composite metal oxides such as LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , and LiMn ₂ O ₄ are used. Further, the positive electrode active material is made of a conductive additive similar to that of the negative electrode, and a binder such as SBR, NBR, acrylic rubber, hydroxyethyl cellulose, carboxymethyl cellulose, polyvinylidene fluoride, and the boiling point at 100 ° C. in water or the above normal pressure. The positive electrode slurry prepared by mixing in a solvent of 300 ° C. or lower can be applied to a positive electrode current collector such as aluminum and the solvent can be dried to obtain a positive electrode.

In the nonaqueous electrolyte battery of this embodiment, an electrolytic solution in which an electrolyte is dissolved in a solvent can be used. The electrolyte solution may be liquid or gel as long as it is used for a normal non-aqueous electrolyte battery, and if it appropriately selects a battery that functions as a battery depending on the type of the negative electrode active material and the positive electrode active material. Good. Specific electrolytes, for example, also known lithium salt is any conventionally _{available, LiClO 4, LiBF 6, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10 _{, LiAlC l4, LiCl, LiBr,} LiB (C 2 H 5) 4, CF 3 SO 3 Li, CH 3 SO 3 Li, LiCF 3 SO 3, LiC 4 F 9 SO 3, Li (CF 3 SO 2) 2 N And lower aliphatic lithium carboxylates.

  A solvent (electrolyte solvent) for dissolving such an electrolyte is not particularly limited. Specific examples include carbonates such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate and vinylene carbonate; lactones such as γ-butyllactone; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, 2 -Ethers such as ethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran; Sulfoxides such as dimethyl sulfoxide; Oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; Nitrogen-containing compounds such as acetonitrile and nitromethane Organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate; triethyl phosphate, dimethyl carbonate, carbonic acid Inorganic acid esters such as ethyl; diglymes; triglymes; sulfolanes; oxazolidinones such as 3-methyl-2-oxazolidinone; sultones such as 1,3-propane sultone, 1,4-butane sultone, naphtha sultone, etc. These may be used alone or in combination of two or more. When a gel electrolyte is used, a nitrile polymer, an acrylic polymer, a fluorine polymer, an alkylene oxide polymer, or the like can be added as a gelling agent.

  Although there is no limitation in particular as a method of manufacturing the nonaqueous electrolyte battery of this embodiment, For example, the following manufacturing method is illustrated. That is, the negative electrode and the positive electrode are overlapped with each other via a separator such as a polypropylene porous membrane, wound or folded according to the shape of the battery, put into a battery container, injected with an electrolyte, and sealed. The shape of the battery may be any known coin type, button type, sheet type, cylindrical type, square type, flat type, and the like.

  The nonaqueous electrolyte battery of this embodiment is a battery that achieves both improved adhesion and improved battery characteristics, and is useful for various applications. For example, the battery is very useful as a battery used in a portable terminal that is required to be small, thin, light, and have high performance.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1
<Binder composition>
Using 25 g (0.16 mol) of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.5, ring-opening ratio 96%) as a negative electrode binder composition, 10 wt% Aqueous solutions were prepared and used in the following tests.

<Swellability test of binder composition>
The film obtained from the binder composition was vacuum-dried at 105 ° C. for 6 hours, and the mass after drying was defined as the dry mass (Wd). This film was added to a mixed solvent system (EC / EMC = 3/7 vol%, VC 2 wt%) in which vinylene carbonate (VC) was added to ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a glove box under an argon gas atmosphere. (Miwa Seisakusho Co., Ltd.) The mass after immersion for 1 week (168 hours) at 25 ° C. was defined as the swelling mass (Ww), and the swelling ratio was calculated by the following formula.
Swelling rate = Ww / Wd

<Preparation of slurry for nonaqueous electrolyte battery>
Slurry preparation is based on 100 parts by weight of natural graphite (DMGS, manufactured by BYD) as an active material, 4.21 parts by weight of a 10 wt% aqueous solution of a negative electrode binder composition as a solid content, and as a conductive assistant (conductivity imparting agent). Carbon black (“Super-P” (registered trademark) manufactured by Timcal Co., Ltd.) as a solid content, 1.05 parts by weight was charged into a special container, and kneaded using a planetary stirrer (ARE-250, manufactured by Sinky). In order to adjust the viscosity of the slurry, an electrode coating slurry was prepared by adding water at the time of kneading and kneading again. The composition ratio in the slurry is, as a solid content, graphite powder: conductive aid: binder composition = 100: 1.05: 4.21. Moreover, the water as a solvent was 48.4 wt% with respect to the active material.

<Preparation of negative electrode for nonaqueous electrolyte battery>
The obtained slurry was coated on a copper foil (C1100H, manufactured by UACJ) as a current collector using a bar coater (T101, manufactured by Matsuo Sangyo), and then heated at 80 ° C. for 30 minutes with a hot air dryer (manufactured by Yamato Kagaku). After the primary drying, rolling was performed at a press pressure of 20 MPa using a roll press (made by Hosen). Then, after punching out as a battery electrode (φ14 mm), a coin battery electrode was produced by secondary drying under reduced pressure conditions at 120 ° C. for 3 hours. The electrode density of the produced electrode was 1.86 cm ³ / g.

<Production of battery>
The battery coating electrode obtained above was transferred to a glove box (Miwa Seisakusho) under an argon gas atmosphere. A metal lithium foil (thickness 0.2 mm, φ16 mm) was used for the positive electrode. In addition, a polypropylene system (Celgard # 2400, manufactured by Polypore) is used as a separator, and the electrolyte is ethylene carbonate (EC) of lithium hexafluorophosphate (LiPF6) and vinylene carbonate (VC ) Was added using a mixed solvent system (1M-LiPF ₆ , EC / EMC = 3/7 vol%, VC 2 wt%) to prepare a coin battery (2032 type).

<Evaluation method: charge / discharge characteristic test>
The produced coin battery was subjected to a charge / discharge test using a commercially available charge / discharge tester (TOSCAT3100, manufactured by Toyo System). The coin battery is placed in a constant temperature bath at 25 ° C., and charging is performed with a constant current of 0.1 C (about 0.5 mA / cm ² ) with respect to the amount of active material until the voltage reaches 0 V with respect to the lithium potential. On the other hand, constant voltage charging of 0 V was carried out until a current of 0.02 mA. The capacity at this time was defined as a charging capacity (mAh / g). Next, a constant current discharge of 0.1 C (about 0.5 mA / cm ² ) was performed up to 1.5 V with respect to the lithium potential, and the capacity at this time was defined as a discharge capacity (mAh / g). The difference between the initial discharge capacity and the charge capacity was taken as the irreversible capacity, and the percentage of the discharge capacity / charge capacity was taken as the charge / discharge efficiency. As the direct current resistance of the coin battery, a resistance value after being charged once (fully charged state) was adopted. The results are shown in Table 1 below.

  The discharge capacity maintenance rate (%) of the coin battery was the ratio of the 20th discharge capacity to the 1st discharge capacity using the charge / discharge conditions described above. The results are shown in Table 1 below.

(Example 2)
A 10 wt% aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 0.7, ring opening rate 98%) was prepared as a binder composition for a negative electrode.

  And the slurry for negative electrodes was produced by the method similar to the said Example 1. FIG. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. The results are shown in Table 1 below.

(Example 3)
A 10 wt% aqueous solution of a water-soluble lithium-modified isobutene-maleic anhydride copolymer resin (average molecular weight 325,000, neutralization degree 1.0, ring opening rate 100%) was prepared as a binder composition for a negative electrode.

  And the slurry for negative electrodes was produced by the method similar to the said Example 1. FIG. Further, a coated negative electrode was prepared by the same method as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. The results are shown in Table 1 below.

Example 4
Using the same binder resin composition as in Example 1, a slurry for a nonaqueous electrolyte battery and a coated negative electrode were produced in the same manner as in Example 1 above. Rolling was performed using a roll press at a press pressure of 3 MPa. Then, the coin battery was obtained by the same method as Example 1, and the charge / discharge characteristic test was done. The results are shown in Table 1 below.

(Example 5)
Using the same binder resin composition as in Example 1, a slurry for a nonaqueous electrolyte battery and a coated negative electrode were produced in the same manner as in Example 1 above. Rolling was performed using a roll press at a press pressure of 33 MPa. Then, the coin battery was obtained by the same method as Example 1, and the charge / discharge characteristic test was done. The results are shown in Table 1 below.

(Example 6)
A water-soluble lithium-modified methyl vinyl ether-maleic anhydride copolymer resin (average molecular weight 630,000, ring-opening rate 96%, neutralization degree 0.5) was used as the binder composition, and the swellability test was conducted in the same manner as in Example 1. And the swelling ratio was calculated. The results are shown in Table 1 below.

  Using a 10 wt% aqueous solution of the binder composition, a slurry for a non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Thereafter, coating and rolling were performed in the same manner as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. The results are shown in Table 1 below.

(Example 7)
Using a water-soluble lithium-modified ethylene-maleic anhydride copolymer resin (average molecular weight average molecular weight 100,000 to 600,000, ring-opening rate 96%, neutralization degree 0.5) as a binder composition, Similarly, the swellability test was performed and the swelling ratio was calculated. The results are shown in Table 1 below.

  Using a 10 wt% aqueous solution of the binder composition, a slurry for a non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Thereafter, coating and rolling were performed in the same manner as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. The results are shown in Table 1 below.

(Example 8)
As the binder composition, a water-soluble lithium-modified styrene-maleic anhydride copolymer resin (average molecular weight average molecular weight 10,000 to 15,000, ring-opening rate 96%, neutralization degree 0.5) was used. A swellability test was conducted by the same method as above to calculate the swelling rate. The results are shown in Table 1 below.

  Using a 10 wt% aqueous solution of the binder composition, a slurry for a non-aqueous electrolyte battery was prepared in the same manner as in Example 1. Thereafter, coating and rolling were performed in the same manner as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. The results are shown in Table 1 below.

Example 9
Using the same binder composition as in Example 1, a slurry for a nonaqueous electrolyte battery was produced using an active material (hard carbon) produced by the following production method. With respect to 100 parts by weight of the active material (hard carbon), a 10 wt% aqueous binder composition similar to that in Example 1 was charged in a dedicated container with 4.17 parts by weight as a solid content, and a planetary stirrer (ARE-250, And kneading using Shinkey Co., Ltd. In order to adjust the viscosity of the slurry, an electrode coating slurry was prepared by adding water at the time of kneading and kneading again. The composition ratio of the active material and the binder in the slurry is, as solid content, hard carbon powder: binder composition = 100: 4.17 (no conductive auxiliary added). Moreover, the water as a solvent was 46.8 wt% with respect to the active material.

<Production of active material (hard carbon)>
The coconut shell was crushed and dry-distilled at 500 ° C. to obtain coconut shell char having a particle size of 2.360 to 0.850 mm (containing 98 wt% of particles having a particle size of 2.360 to 0.850 mm). 100 g of this coconut shell char was subjected to vapor phase deashing treatment at 870 ° C. for 30 minutes while supplying nitrogen gas containing 1% by volume of hydrogen chloride gas at a flow rate of 10 L / min. Thereafter, only the supply of hydrogen chloride gas was stopped, and while supplying nitrogen gas at a flow rate of 10 L / min, vapor phase deoxidation treatment was further performed at 900 ° C. for 30 minutes to obtain a carbon precursor.

  The obtained carbon precursor was roughly pulverized to an average particle size of 10 μm using a ball mill, and then pulverized and classified using a compact jet mill (manufactured by Seishin Enterprise Co., Ltd., Kodget System α-mkIII) to obtain an average particle size. A carbon precursor of 9.6 μm was obtained. 9.1 g of this carbon precursor was mixed with 0.9 g of polystyrene (manufactured by Sekisui Plastics Co., Ltd., average particle size 400 μm, residual carbon ratio 1.2%). 10 g of this mixture was placed in a graphite sheath (length 100 mm, width 100 mm, height 50 mm), 1320 ° C. at a heating rate of 60 ° C. per minute under a 5 L / min nitrogen flow rate in a high-speed heating furnace manufactured by Motoyama Co., Ltd. After raising the temperature to 1, the carbon was held for 11 minutes and cooled naturally to produce hard carbon.

  Thereafter, coating and rolling were performed in the same manner as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. The results are shown in Table 1 below.

(Example 10)
Using the same binder composition as in Example 1, slurry for a non-aqueous electrolyte battery was prepared. Slurry preparation is based on 100 parts by weight of SiO (Sigma Aldrich) as an active material, 5.56 parts by weight of a 10 w% aqueous solution of a binder composition for a non-aqueous electrolyte battery as a solid content, and as a conductive assistant (conductivity imparting agent). Acetylen black (“DENKA BLACK” (registered trademark) manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as a solid content and 5.56 parts by weight was charged into a special container and kneaded using a planetary stirrer (ARE-250, manufactured by Shinky Corporation). . In order to adjust the viscosity of the slurry, an electrode coating slurry was prepared by adding water at the time of kneading and kneading again. The composition ratio in the slurry is SiO: binder composition: conducting aid = 100: 5.56: 5.56 as solid content. Moreover, the water as a solvent was 70 wt% with respect to the active material.

  Thereafter, coating and rolling were performed in the same manner as in Example 1 to obtain a coin battery, and a charge / discharge characteristic test was performed. The results are shown in Table 1 below.

(Comparative Example 1)
Adjust the binder composition ratio of SBR (TRD2001), which is a conventional aqueous negative electrode binder composition, and CMC-Na (cellogen BSH-6) as a thickener to be SBR: CMC = 2: 1 as a solid content, and A swelling test was performed by the same method as in Example 1, and the swelling rate was calculated. The results are shown in Table 1 below.

  A negative electrode coating slurry was prepared using an aqueous SBR emulsion aqueous solution (TRD2001, 48.3 wt%), which is a conventional aqueous negative electrode binder composition, and CMC-Na (cellogen BSH-6, 10 wt%) as a thickener. The composition ratio of the active material, the binder composition, the thickener, and the conductive additive in the slurry is a solid content of graphite powder: SBR binder: CMC thickener: conductive additive = 100: 3.16: 1.05: 1.05. Moreover, the coating negative electrode was produced by the method similar to the said Example 1, the coin battery was obtained, and the charge / discharge characteristic test was done. The results are shown in Table 1 below.

(Comparative Example 2)
Using the same binder resin composition as in Comparative Example 1, a slurry for a nonaqueous electrolyte battery and a coated negative electrode were produced in the same manner as in Example 4 above. The composition ratio of the active material, the binder composition, and the thickener in the slurry was, as a solid content, hard carbon: SBR binder: CMC thickener = 100: 3.13: 1.04 (the conductive auxiliary agent was non-conductive). Addition). Moreover, the coating negative electrode was produced by the method similar to the said Example 1, the coin battery was obtained, and the charge / discharge characteristic test was done. The results are shown in Table 1 below.

(Comparative Example 3)
Using the same binder resin composition as in Comparative Example 1, a slurry for a nonaqueous electrolyte battery and a coated negative electrode were produced in the same manner as in Example 5 above. The composition ratio of the active material, the binder composition, the thickener, and the conductive assistant (Denka Black) in the slurry is expressed as a solid content: SiO: SBR binder: CMC thickener: conductive assistant = 100: 4.44: 1 11: 5.56. Moreover, the coating negative electrode was produced by the method similar to the said Example 1, the coin battery was obtained, and the charge / discharge characteristic test was done. The results are shown in Table 1 below.

(Discussion)
In Examples 1 and 2 having different degrees of neutralization, although the swelling rate increased as the amount of carboxylic acid increased, the neutralization salt hardly changed the battery characteristics and reduced resistance and maintained high discharge capacity. The rate was shown to be realized.

  It was shown that Example 4 which performed the test which changed the press pressure can produce a high-density electrode with a low press pressure with respect to the comparative example 1 using the existing general purpose binder. Moreover, in Example 5, which was tested at a higher press pressure than Example 1, the electrode density was further increased. Further, as is apparent from Table 1, it was shown that the batteries of Examples 1 and 4 to 5 achieve a low resistance and a high discharge capacity retention rate as compared with Comparative Example 1.

  Even in Examples 6 to 8 using a binder composition containing a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerizing an α-olefin and maleic acid different from those in Example 1, high electrode density and low resistance are used. A high discharge capacity retention rate was obtained.

Moreover, also in Examples 9-10 in which the active material was changed, the electrode density, resistance, and discharge capacity retention rate were superior to Comparative Examples 2-3 using the same active material.

Claims (5)

  a neutralized salt of an α-olefin-maleic acid copolymer obtained by copolymerization of an α-olefin and maleic acid, and a swelling ratio to the electrolytic solution of 1.0 or more and 1.1 or less. A binder composition for a non-aqueous electrolyte battery, which is characterized.   A binder aqueous solution for a non-aqueous electrolyte battery comprising the binder composition according to claim 1 and water.   A slurry composition for a non-aqueous electrolyte battery, comprising the binder composition according to claim 1, an active material, and water.   A nonaqueous electrolyte battery negative electrode obtained by binding a mixed layer containing the binder composition according to claim 1 and an active material to a current collector. The nonaqueous electrolyte battery which has a nonaqueous electrolyte battery negative electrode of Claim 4.