Additives for secondary battery electrodes

Abstract

Provided is a secondary battery electrode additive with which an active material can be coated without heat treatment that is performed at a high temperature for a long period of time, an alkaline component can be neutralized, and the decomposition of an electrolytic solution can be suppressed. For example, provided is a secondary battery electrode additive comprising a boronic acid derivative represented by formula (5). (In the formula, R1-R5 each independently represent a hydrogen atom, an alkyl group, an ester group, a glycol chain, an alkoxy group, or a hydroxy group, and R6 represents a hydrogen atom, a methyl group, or an ethyl group.)

Description

Technical Field

[0001] The present invention relates to an additive for a secondary battery electrode.

Background Art

[0002] Lithium-ion secondary batteries have a high energy density and high voltage, and also have no memory effect during charge and discharge. Therefore, they are currently the most actively developed secondary batteries. With the expansion of their applications and usage amounts, further reduction of resistance, extension of lifespan, increase in capacity, improvement of safety, and reduction of cost are required.

[0003] Lithium-ion secondary batteries have a problem of deteriorating when charged and discharged repeatedly. Although various factors have been reported as the mechanisms of deterioration, the main reasons include the deterioration of the active material due to moisture remaining in trace amounts inside the battery and the decomposition of the electrolyte, or the increase in internal resistance due to the formation of decomposition products of the electrolyte, and the generation of isolated active materials due to cracks occurring in the electrode binder layer.

[0004] In order to solve such problems, Non-Patent Document 1 reports a technique of coating the surface of the positive electrode active material with metal oxides such as Mg, Al, Ti, Sn, Si, and Cu, phosphorus-based compounds, and carbon, etc. However, it cannot be said that the problems of lifespan deterioration and gas generation due to the decomposition of the electrolyte during charge and discharge can be sufficiently solved.

[0005] Also, as positive electrode active materials for lithium-ion secondary batteries capable of obtaining a battery voltage of around 4V, inorganic compounds such as transition metal oxides containing alkali metals and transition metal chalcogens are known. Among these, high-nickel positive electrode active materials represented by LixNiO2 have a high discharge capacity and are attractive positive electrode materials. However, on the surface of the high-nickel positive electrode active material, there are many impurities such as residues of raw materials, LiOH formed by proton exchange reaction with moisture, and Li2CO3 generated by the reaction of this LiOH with carbon dioxide gas in the air.

[0006] In particular, because LiOH is an alkaline component, it causes gelation of the slurry when mixing the composition containing the positive electrode active material, the binder polyvinylidene fluoride (PVdF), and the solvent N-methyl-2-pyrrolidone (NMP) during the process of manufacturing the positive electrode, or when coating the mixed composition. Furthermore, the alkaline component not only increases the resistance of the battery by corroding the aluminum commonly used as the current collector foil of the positive electrode, but also reacts with the electrolyte inside the battery, increasing the battery's resistance and worsening its lifespan. On the other hand, Li2CO3 decomposes during charging and discharging, generating CO2 and CO3 gases. These gases increase the pressure inside the battery, which can cause it to swell and worsen its cycle life. Furthermore, the increased internal pressure due to the generated gases can potentially damage the battery.

[0007] Furthermore, high-nickel cathode active materials have low electrode volume density and poor electrode winding properties due to their composition and shape. High-nickel cathode active materials are Li x Because the true density of the powder is lower compared to CoO2, the reduction in electrode volume density cannot be improved by changing the composition. Furthermore, due to its poor electrode winding properties, while cylindrical batteries can be manufactured, flat batteries used in mobile phones and other devices are difficult to manufacture because the curve at the point of electrode folding is sharp, causing the electrodes to crack or break during the electrode folding process or during molding by pressing after winding. To overcome these problems, methods such as increasing the thickness of the electrode foil to increase its strength or lowering the volume density of the positive electrode active material coated on the electrode foil are commonly employed. However, these methods reduce the amount of positive electrode active material contained per unit battery volume, resulting in insufficient capacity being obtained.

[0008] To address the above-mentioned problems of lithium-ion secondary batteries using high-nickel cathode active materials, Patent Document 1 reports a method in which the cathode active material is treated with fluorine gas to immobilize residual LiOH as LiF, thereby preventing gelation and suppressing gas generation. However, fluorine gas is highly toxic and difficult to handle, and the LiF produced as a by-product increases the internal resistance of the battery, and the capacity also decreases due to corrosion of the cathode active material by fluorine gas. Furthermore, residual fluorine reacts with trace amounts of moisture present in the active material and electrolyte to produce hydrogen fluoride, which easily causes cycle degradation.

[0009] Patent Document 2 reports that by adding phosphorous acid (H3PO3) to the electrode, the distribution of the binder and conductive additive in the positive electrode can be altered, thereby improving the winding properties of the electrode. While this method is expected to suppress degradation by neutralizing the alkaline component, there is a problem that lithium phosphate salts, which are produced as by-products, increase the internal resistance of the battery. Furthermore, since lithium phosphate salts are inorganic salts, they have poor coating properties for the active material, and the active material remains in contact with the electrolyte, causing the electrolyte to decompose and the battery to degrade.

[0010] Patent Document 3 reports a method of coating the surface of a lithium transition metal oxide by mixing it with boron-based compounds such as boron oxides or oxoacids and then heat-treating the mixture. However, this method has the problem of requiring high-temperature heat treatment, resulting in a high process load, and also failing to sufficiently suppress the decomposition of the electrolyte.

[0011] Patent Document 4 reports a method for suppressing the oxidative decomposition reaction between the positive electrode active material and the electrolyte by forming a coating layer of an organic phosphate containing triphenyl phosphate on the surface of the positive electrode active material. However, this method also has the problem of a high process load because it requires heat treatment at high temperatures for a long period of time. In addition, it has the problem that the effect of reducing the resistance of the battery is not obtained because the neutralization effect of the alkaline component is insufficient.

[0012] Patent Document 5 reports that a compound having a CN bond and a polymerizable unsaturated bond, consisting of a salt of a monovalent metal cation and a boron-based compound anion, functions as an electrode protective film-forming agent, providing an electrode or electrolyte for secondary batteries with excellent output characteristics and long-term cycle characteristics and low electrode resistance. In this technology, when a voltage is applied to the resulting battery, a polymerized film is formed on the surface of the electrode active material, and the action of this polymerized film improves the charge-discharge cycle characteristics and output characteristics, while also reducing electrode resistance. However, the above compound has the problem of low yield and high cost during synthesis due to its complex structure, making it impractical. Furthermore, it does not have the function of neutralizing alkaline impurities contained in the positive electrode active material, which are a factor in battery degradation, thus reducing the battery's resistance. transformation There is also the problem that the desired effect may not be fully achieved.

[0013] Patent Document 6 reports that by forming a protective layer containing a boron-based anion receptor and a block copolymer, battery degradation can be suppressed by inhibiting the reactivity of lithium salt anions with the anion receptor, and the ionic conductivity between the positive electrode and the electrolyte can be improved. However, the above-mentioned anion receptor has a poor effect in neutralizing alkaline components, and therefore a problem in that sufficient effect to suppress degradation cannot be obtained. In addition, there are problems such as a decrease in energy density due to the thickness of the protective layer, and a decrease in lithium ion diffusion due to a reduction in pores inside the electrode. [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] Japanese Patent Publication No. 2006-286240 [Patent Document 2] Patent No. 5418626 [Patent Document 3] Patent No. 6284542 [Patent Document 4] Patent No. 6429172 [Patent Document 5] Patent No. 6165162 [Patent Document 6] U.S. Patent Publication No. 2017 / 0365855 [Non-patent literature]

[0015] [Non-Patent Document 1] Journal of Alloys and Compounds 706 (2017) 24-40 [Overview of the project] [Problems that the invention aims to solve]

[0016] This invention has been made in view of these circumstances, and aims to provide an additive for secondary battery electrodes that can coat the active material without high-temperature and long-duration heat treatment, can neutralize alkaline components, and can suppress the decomposition of the electrolyte. [Means for solving the problem]

[0017] As a result of diligent research to achieve the above objective, the inventors of the present invention have discovered that an additive for secondary battery electrodes consisting of a boronic acid derivative can coat the active material without high-temperature and long-duration heat treatment, and can also neutralize alkaline components and suppress the decomposition of the electrolyte, thus completing the present invention.

[0018] In other words, the present invention provides the following additives for secondary battery electrodes. 1. Additive for secondary battery electrodes consisting of boronic acid derivatives. 2. An additive for secondary battery electrodes, wherein the boronic acid derivative is a reaction product of an arylboronic acid represented by the following formula (1) and a reactive compound having at least two reactive groups selected from the group consisting of a hydroxyl group, a carbonyl group, an isocyanate group, and an amino group. [ka] (In the formula, Ar represents an optionally substituted aryl group or an optionally substituted heteroaryl group.) 3. Additive for secondary battery electrodes, wherein the above Ar is a phenyl group which may have substituents. 4. An arylboronic acid is an additive for secondary battery electrodes of type 2 or 3, represented by the following formula (2). [ka] (In the formula, R 1 ~R 5 Each of these independently represents a hydrogen atom, an alkyl group, an ester group, a glycol chain, an alkoxy group, or a hydroxyl group. 5. Additives for secondary battery electrodes, any of 2 to 4, wherein the reactive compound is at least one selected from the group consisting of trimethylolmethane, trimethylolethane, trimethylolpropane, glycerin, mannitol, pentaerythritol, dipentaerythritol, diaminonaphthalene, phenylenediamine, N-methyliminodiacetic acid, oxalic acid, fumaric acid, phthalic acid, succinic acid, citric acid, isocitric acid, oxalosuccinic acid, oxaloacetic acid, aconitic acid, p-toluenesulfonyl isocyanate, chlorosulfonyl isocyanate, polyvinyl alcohol and its derivatives, and polyvinyl alcohol copolymer and its derivatives. 6. A secondary battery electrode additive from any of 2 to 5, wherein the reactive compound has three or more of the above-mentioned reactive groups. 7. A reactive compound having three or more hydroxyl groups, which is an additive for secondary battery electrodes. 8. Additives for secondary battery electrodes, wherein the boronic acid derivative contains a repeating unit represented by the following formula (3) or the following formula (4). [ka] (In the formula, Ar has the same meaning as above, R 6 (This represents a hydrogen atom, a methyl group, or an ethyl group.) 9. A secondary battery electrode additive of any of 4 to 7, wherein the boronic acid derivative contains a repeating unit represented by the following formula (5) or the following formula (6). [Chemical formula] (wherein, R 1 ~R 5 represents the same meaning as described above, and R 6 represents a hydrogen atom, a methyl group or an ethyl group.) 10. The boronic acid derivative is an additive for a secondary battery electrode represented by any one of the following formulas (7) to (9). [Chemical formula] (wherein, R 1 ~R 5 represents the same meaning as described above, and R 6 represents a hydrogen atom, a methyl group or an ethyl group.) 11. An electrode composition comprising an additive for a secondary battery electrode of any one of 1 to 10 and an active material. 12. The electrode composition of 11, further comprising a second additive different from the additive for a secondary battery electrode of any one of 1 to 10. 13. The electrode composition of 12, wherein the second additive is at least one selected from the group consisting of water, a hydroxyl group-containing compound, and a compound containing a nitrogen atom and a carbonyl structure. 14. The electrode composition of 12 or 13, wherein the second additive is at least one selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol and its derivatives, and polyvinyl alcohol copolymers and their derivatives. 15. The electrode composition of any one of 11 to 14, wherein the active material is an oxide containing Li and Ni and is a composition for a positive electrode. 16. The active material is Li a Ni (1-x-y) Co x M 1 y M 2 z X w O2 (1.00 ≦ a ≦ 1.50, 0.00 ≦ x ≦ 0.50, 0 ≦ y ≦ 0.50, 0.000 ≦ z ≦ 0.020, 0.000 ≦ w ≦ 0.020, M 1 is at least one selected from the group consisting of Mn and Al, M 2Fifteen electrode compositions for a positive electrode, wherein the composition is represented by at least one selected from the group consisting of Zr, Ti, Mg, W, and V. 17. An electrode composition according to any of 11 to 16, containing 0.01 to 10.0% by mass of an additive for secondary battery electrodes. 18. An electrode composition of any of 11 to 14, wherein the active material is at least one selected from the group consisting of graphite, Si, SiO, lithium titanate (LTO), and metallic Li, and is a composition for the negative electrode. 19. Electrode compositions comprising 0.02 to 10.0% by mass of an additive for secondary battery electrodes. 20. An electrode for a secondary battery, comprising a current collector substrate and an active material layer formed on at least one surface of the current collector substrate, wherein the active material layer is formed of any of the electrode compositions 11 to 14. 21. A positive electrode for a secondary battery, comprising a current collector substrate and an active material layer formed on at least one surface of the current collector substrate, wherein the active material layer is formed of any of the electrode compositions 15 to 17. 22. A positive electrode for a secondary battery, wherein, after charging and discharging, the intensity ratio ([CF] / [LiF]) of the intensity of the CF peak (686±1.25eV) to the intensity of the LiF peak (683.5±1.25eV), determined by XPS measurement (normalized with the CC-derived peak of C1s as 284eV), is 3.0 or greater. 23. A negative electrode for a secondary battery, comprising a current collector substrate and an active material layer formed on at least one surface of the current collector substrate, wherein the active material layer is formed of electrode composition 18 or 19. 24. A secondary battery comprising at least one electrode selected from the group consisting of 20 secondary battery electrodes, 21 or 22 secondary battery positive electrode, and 23 secondary battery negative electrode. 25. 24 rechargeable batteries, which are lithium-ion rechargeable batteries. 26. 24 rechargeable batteries that are all-solid-state batteries. 27. A method for producing an electrode composition comprising an additive for secondary battery electrodes according to any of 1 to 10 and an active material, A method for producing an electrode composition in which the maximum temperature reached during the preparation of the composition is 60 to 200°C. 28. A method for producing 27 electrode compositions having a maximum temperature of 60 to 150°C. 29. A method for producing 28 electrode compositions having a maximum temperature of 60 to 125°C. [Effects of the Invention]

[0019] The additive for secondary battery electrodes made of the boronic acid derivative of the present invention can coat the active material without high-temperature and long-duration heat treatment, enhance the adhesion between the electrode and the current collector, which is important for electrode winding, and further improve the dispersibility of binder resin and conductive carbon material in the electrode, thereby achieving lower resistance and suppression of degradation. The reasons for these effects are not clear, but they are speculated to be as follows: For example, it is speculated that the alkali components on the surface of the active material can be neutralized, thereby suppressing corrosion of the aluminum foil by alkali components; the boronic acid derivative acts as a protective layer on the surface of the active material, suppressing contact between the electrolyte and the active material, thereby suppressing the decomposition of the electrolyte, and thus suppressing the increase in resistance and degradation of capacity associated with charging and discharging; and it is also speculated that it suppresses the leaching of metal from the active material. [Modes for carrying out the invention]

[0020] The additive for secondary battery electrodes according to the present invention (hereinafter sometimes simply referred to as the additive) consists of a boronic acid derivative. In the present invention, the boronic acid derivative is not particularly limited, but a reaction product of an arylboronic acid represented by the following formula (1) and a reactive compound having at least two reactive groups selected from the group consisting of a hydroxyl group, a carbonyl group, an isocyanate group, and an amino group is preferred.

[0021] [ka]

[0022] In the formula, Ar represents an optionally substituted aryl group or an optionally substituted heteroaryl group.

[0023] Examples of aryl groups include aryl groups having 6 to 20 carbon atoms. Specific examples include phenyl, tolyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, 9-phenanthryl, and biphenyl groups, with phenyl groups being preferred.

[0024] Examples of the substituents mentioned above include alkyl groups having 1 to 20 carbon atoms, ester groups, glycol chains, alkoxy groups having 1 to 20 carbon atoms, and hydroxyl groups.

[0025] The alkyl group having 1 to 20 carbon atoms may be linear, branched, or cyclic. Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, and n-eicosanyl groups. However, alkyl groups having 1 to 18 carbon atoms are preferred, and alkyl groups having 1 to 8 carbon atoms are more preferred.

[0026] As alkoxy groups having 1 to 20 carbon atoms, the alkyl group bonded to the oxygen atom may be linear, branched, or cyclic. Specific examples include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy, t-butoxy, n-pentyloxy, i-pentyloxy, 2-methylbutoxy, 1,1-dimethylpropoxy, neopentyloxy, 3,3-dimethylbutoxy, 1-ethylpropoxy, n-hexyloxy, benzyloxy, naphthylmethyloxy, 1-phenylethyloxy, 2-phenylethyloxy, 2-naphthylethyloxy, and 3,3-diphenylpropoxy groups. However, alkoxy groups having 1 to 18 carbon atoms are preferred, and alkoxy groups having 1 to 8 carbon atoms are more preferred.

[0027] Examples of heteroaryl groups include heteroaryl groups having 2 to 20 carbon atoms. Specific examples include oxygen-containing heteroaryl groups such as 2-furanyl, 3-furanyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl, and 5-isoxazolyl groups; sulfur-containing heteroaryl groups such as 2-thienyl, 3-thienyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 3-isothiazolyl, 4-isothiazolyl, and 5-isothiazolyl groups; and 2-imi Dazolyl, 4-Imidazolyl, 2-Pyridyl, 3-Pyridyl, 4-Pyridyl, 2-Pyrazinyl, 3-Pyrazinyl, 5-Pyrazinyl, 6-Pyrazinyl, 2-Pyrimidyl, 4-Pyrimidyl, 5-Pyrimidyl, 6-Pyrimidyl, 3-Pyridadyl, 4-Pyridadyl, 5-Pyridadyl, 6-Pyridadyl, 1,2,3-Triadin-4-yl, 1,2,3-Triadin-5-yl, 1,2,4-Triadin-3-yl, 1, 2,4-triazin-5-yl, 1,2,4-triazin-6-yl, 1,3,5-triazin-2-yl, 1,2,4,5-tetrazin-3-yl, 1,2,3,4-tetrazin-5-yl, 2-quinolinyl, 3-quinolinyl, 4-quinolinyl, 5-quinolinyl, 6-quinolinyl, 7-quinolinyl, 8-quinolinyl, 1-isoquinolinyl, 3-isoquinolinyl, 4-isoquinolinyl, 5-isoquinolinyl, 6 Examples include nitrogen-containing heteroaryl groups such as -isoquinolinyl, 7-isoquinolinyl, 8-isoquinolinyl, 2-quinoxanyl, 5-quinoxanyl, 6-quinoxanyl, 2-quinazolinyl, 4-quinazolinyl, 5-quinazolinyl, 6-quinazolinyl, 7-quinazolinyl, 8-quinazolinyl, 3-synnorinyl, 4-synnorinyl, 5-synnorinyl, 6-synnorinyl, 7-synnorinyl, and 8-synnorinyl groups.

[0028] The substituents on the heteroaryl group mentioned above are the same substituents as those exemplified for the aryl group mentioned above.

[0029] Ar is preferably a phenyl group which may have substituents, more preferably a phenyl group which is unsubstituted or has an alkyl group having 1 to 20 carbon atoms, and even more preferably a phenyl group which is unsubstituted or has a methyl group.

[0030] The arylboronic acid is preferably one represented by the following formula (2).

[0031] [ka] (In the formula, R 1 ~R 5 Each of these independently represents a hydrogen atom, an alkyl group, an ester group, a glycol chain, an alkoxy group, or a hydroxyl group.

[0032] R 1 ~R 5 Preferably, the group consists of a hydrogen atom and an alkyl group, more preferably a hydrogen atom and an alkyl group having 1 to 20 carbon atoms, even more preferably a hydrogen atom and a methyl group, and even more preferably all hydrogen atoms.

[0033] The reactive compound is preferably one having three or more of the above-mentioned reactive groups, and more preferably one having three or more hydroxyl groups.

[0034] Specific examples of reactive compounds include trimethylolmethane, trimethylolethane, trimethylolpropane, glycerin, mannitol, pentaerythritol, dipentaerythritol, diaminonaphthalene, phenylenediamine, N-methyliminodiacetic acid, oxalic acid, fumaric acid, phthalic acid, succinic acid, citric acid, isocitric acid, oxalosuccinic acid, oxaloacetic acid, aconitic acid, polyvinyl alcohol and its derivatives, as well as polyvinyl alcohol copolymers and their derivatives, p-toluenesulfonyl isocyanate, chlorosulfonyl isocyanate, and the like. In the present invention, trimethylolethane, mannitol, N-methyliminodiacetic acid, polyvinyl alcohol and its derivatives, and p-toluenesulfonyl isocyanate are preferred. These reactive compounds can be used individually or in combination of two or more.

[0035] By using a reactive compound having three or more hydroxyl groups, that is, a boronic acid derivative having a triol-borate structure, it is thought that impurities can be easily decomposed by reacting with LiOH and Li2CO3 through cyclization reactions even at low temperatures. This not only reduces the battery's resistance and suppresses the increase in resistance and degradation of capacity associated with charging and discharging, but also improves safety by suppressing gas generation within the battery. Furthermore, because the triol borate structure can be anionized through a cyclization reaction, allowing it to interact with lithium ions, the protective film formed by the boronic acid triol can also be expected to exhibit lithium transport properties. Furthermore, since boronic acid triols are expected to function as Lewis acids, they can interact with electrolytes such as ethylene carbonate through Lewis acid-base interactions. This is expected to promote the desolvation of lithium ions at the active material interface, thereby reducing resistance. In addition, because they can interact with acid-base interactions similar to the anions of lithium salts, they can stabilize the anions and suppress reactivity, which is thought to suppress the increase in resistance and the degradation of capacity associated with charging and discharging.

[0036] Examples of boronic acid derivatives obtained by reacting the aforementioned arylboronic acid with a reactive compound include those represented by the following formula (3) (hereinafter sometimes referred to as "monomolecular type") and those containing repeating units represented by the following formula (4) (hereinafter sometimes referred to as "polymer type").

[0037] [ka] (In the formula, Ar has the same meaning as above, R 6 (This represents a hydrogen atom, a methyl group, or an ethyl group.)

[0038] As a monomolecule type, one represented by the following formula (5) is more preferred, and as a polymer type, one containing repeating units represented by the following formula (6) is more preferred.

[0039] [ka] (In the formula, R 1 ~R 5 This expresses the same meaning as above, R 6 (This represents a hydrogen atom, a methyl group, or an ethyl group.)

[0040] Another example of a monomolecule type is the borate salt represented by formula (7) below, but in the present invention, the one represented by formula (5) is preferred.

[0041] [ka] (In the formula, R 1 ~R 5 This expresses the same meaning as above, R 6 (This represents a hydrogen atom, a methyl group, or an ethyl group.)

[0042] Specific examples of monomolecule types include those represented by the following formulas (8-1) to (8-6).

[0043] [ka]

[0044] Specific examples of polymer types include those containing repeating units represented by the following formulas (9-1) to (9-3).

[0045] [ka] (In the formula, n represents a natural number between 1 and 10,000, m represents a natural number between 1 and 10,000, and l represents a natural number between 1 and 1,000.)

[0046] The above n is preferably a natural number between 10 and 10,000, and more preferably a natural number between 50 and 10,000. The above m is preferably a natural number between 10 and 10,000, and more preferably a natural number between 50 and 10,000. The above l is preferably a natural number between 10 and 1,000, and more preferably a natural number between 50 and 1,000.

[0047] In the case of polymer types, the average molecular weight is not particularly limited, but a weight-average molecular weight of 1,000 to 2,000,000 is preferred, and a weight-average molecular weight of 2,000 to 1,000,000 is more preferred. The weight-average molecular weight is the polystyrene equivalent value obtained by gel permeation chromatography (GPC).

[0048] In the present invention, in polymer-type additives, from the viewpoint of obtaining a thin film with high adhesion reproducibly, it is preferable that the repeating unit represented by formula (6) is contained in 10 to 100 mol%, more preferably 30 to 100 mol%, and even more preferably 50 to 100 mol% of the total repeating units.

[0049] Polyvinyl alcohol and its derivatives, as well as polyvinyl alcohol copolymers and their derivatives, may contain vinyl acetate structures derived from the raw material vinyl acetic acid as repeating units. When vinyl acetate structures are included, the amount is preferably 50 mol% or less of the total repeating units, and more preferably 30 mol% or less. Furthermore, the molecular weight of polyvinyl alcohol and its derivatives, as well as polyvinyl alcohol copolymers and their derivatives, is not particularly limited. For example, a number-average molecular weight of approximately 1,000 to 500,000, preferably 10,000 to 100,000, can be used. The weight-average molecular weight is the polystyrene equivalent value obtained by GPC.

[0050] The reaction between arylboronic acid and a reactive compound can be carried out by heating in a solvent to a predetermined temperature. The solvent used in the above reaction is not particularly limited as long as it can disperse or dissolve the starting materials used. Examples of such solvents include dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone (NMP), hexamethylphosphate triamide, acetonitrile, acetone, alcohols (methanol, ethanol, 1-propanol, 2-propanol, benzyl alcohol, etc.), glycols (ethylene glycol, triethylene glycol, etc.), cellosolves (ethyl cellosolve, methyl cellosolve, etc.), polyhydric alcohols (glycerin, pentaerythritol, etc.), tetrahydrofuran, esters (ethyl acetate, butyl acetate, etc.), aromatic hydrocarbons (benzene, toluene, xylene, etc.), aliphatic hydrocarbons (pentane, hexane, heptane, hexadecane, etc.), halogenated aliphatic hydrocarbons (chlorobenzene, dichlorobenzene, trichlorobenzene, etc.), and oleylamines. These solvents can be used individually or in combination of two or more. Furthermore, these solvents should be appropriately selected depending on the raw materials used. Among these, hydrophobic solvents are preferred, and toluene is preferred, as the reaction can be carried out using the Deanstark process.

[0051] The reaction temperature for the above reaction is typically between 40 and 200°C. The reaction time is selected from various options depending on the reaction temperature, but is usually between 30 minutes and 50 hours.

[0052] The obtained boronic acid derivative may be used as is, or after diluting or concentrating the reaction solution, or after isolation and dissolving in a suitable solvent. Examples of such solvents include those mentioned above.

[0053] The electrode composition of the present invention comprises the above-mentioned additive for secondary battery electrodes and an active material, and can be used as either a positive electrode or a negative electrode composition depending on the type of active material selected.

[0054] As the active material, various active materials conventionally used in electrodes for secondary batteries can be used. For example, in the case of lithium secondary batteries and lithium-ion secondary batteries, chalcogen compounds or lithium-ion-containing chalcogen compounds capable of adsorbing and detaching lithium ions, polyanionic compounds, elemental sulfur and its compounds, etc., can be used as the positive electrode active material.

[0055] Examples of chalcogen compounds capable of adsorbing and detaching lithium ions include FeS2, TiS2, MoS2, V2O6, and V6O6. 13 Examples include MnO2. Examples of lithium ion-containing chalcogen compounds include LiCoO2, LiMnO2, LiMn2O4, LiMo2O4, LiV3O8, LiNiO2, Li x Ni y M 1-y O2(M represents at least one metallic element selected from Co, Mn, Ti, Cr, V, Al, Sn, Pb, and Zn, with 0.05 ≤ x ≤ 1.10 and 0.5 ≤ y ≤ 1.0), Li a Ni (1-x-y) Co x M 1 y M 2 z X w O2(M 1 M is at least one selected from the group consisting of Mn and Al. 2represents at least one element selected from the group consisting of Zr, Ti, Mg, W, and V, such as 1.00≦a≦1.50, 0.00≦x≦0.50, 0≦y≦0.50, 0.000≦z≦0.020, 0.000≦w≦0.020). Examples of polyanionic compounds include LiFePO4. Examples of sulfur compounds include Li2S and rubeanoic acid. These active materials can be used individually or in combination of two or more.

[0056] In this invention, among the above active materials, an oxide containing Li and Ni, or Li a Ni (1-x-y) Co x M 1 y M 2 z X w O2(M 1 M is at least one selected from the group consisting of Mn and Al. 2 (where a represents at least one selected from the group consisting of Zr, Ti, Mg, W, and V, and preferably 1.00≦a≦1.50, 0.00≦x≦0.50, 0≦y≦0.50, 0.000≦z≦0.020, 0.000≦w≦0.020).

[0057] The content of the above-mentioned active material is preferably 90.0 to 99.99% by mass in the composition, and more preferably 92.0 to 98.0% by mass.

[0058] Furthermore, in the electrode composition for the positive electrode, the content of the above-mentioned secondary battery electrode additive is preferably 0.01 to 10.0% by mass, more preferably 0.01 to 5.0% by mass, even more preferably 0.01 to 1.0% by mass, even more preferably 0.01 to 0.8% by mass, and most preferably 0.01 to 0.45% by mass.

[0059] On the other hand, as the negative electrode active material constituting the above-mentioned negative electrode, alkali metals, alkali alloys, at least one element selected from groups 4 to 15 of the periodic table that intercepts and releases lithium ions, oxides, sulfides, nitrides, or carbon materials capable of reversibly intercepting and releasing lithium ions can be used.

[0060] Examples of alkali metals include Li, Na, and K, while examples of alkali metal alloys include Li-Al, Li-Mg, Li-Al-Ni, Na-Hg, and Na-Zn. Examples of elemental elements selected from groups 4-15 of the periodic table that intercept and deintercept lithium ions include silicon, tin, aluminum, zinc, and arsenic. Other oxides include silicon monoxide (SiO), silicon dioxide (SiO2), tin silicon oxide (SnSiO3), lithium bismuth oxide (Li3BiO4), lithium zinc oxide (Li2ZnO2), and lithium titanate (LTO, Li4Ti5O2). 12 Examples include titanium dioxide, etc. Similarly, lithium iron sulfide (Li x FeS2 (0 ≤ x ≤ 3), Lithium copper sulfide (Li x Examples include CuS(0≦x≦3)). Another example of nitrides is lithium-containing transition metal nitrides, specifically Li x M y Examples include N(M=Co, Ni, Cu, 0≦x≦3, 0≦y≦0.5), lithium iron nitride (Li3FeN4), etc. Examples of carbon materials capable of reversibly intercepting and releasing lithium ions include graphite, carbon black, coke, glassy carbon, carbon fibers, carbon nanotubes, or sintered bodies thereof.

[0061] In this invention, graphite, Si, SiO, LTO, and metallic Li are preferred among these materials.

[0062] The content of the above-mentioned negative electrode active material is preferably 90.0 to 99.98% by mass in the composition, and more preferably 90 to 98% by mass.

[0063] Furthermore, in the electrode composition for the negative electrode, the content of the above-mentioned secondary battery electrode additive is preferably 0.02 to 10.0% by mass, and more preferably 0.02 to 1.0% by mass.

[0064] Furthermore, the electrode composition of the present invention may contain a binder. The binder can be appropriately selected from known materials and is not particularly limited; however, in the present invention, a non-aqueous binder can be suitably used. Specific examples include polyvinylidene fluoride (PVdF), polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer (P(VDF-HFP)), vinylidene fluoride-trifluoroethylene chloride copolymer (P(VDF-CTFE)), polyvinyl alcohol, polyimide, ethylene-propylene-diene terpolymer, styrene-butadiene rubber, carboxymethylcellulose (CMC), polyacrylic acid (PAA), polyaniline, tetrafluoroethylene, polyethylene, and polypropylene. These can be used individually or in combination of two or more.

[0065] The binder content is not particularly limited, but is preferably 0.1 to 5.0% by mass, and more preferably 0.5 to 3.0% by mass, in the composition. By keeping the binder content within the above range, good adhesion to the current collector substrate can be obtained without reducing the capacity.

[0066] Furthermore, the electrode composition of the present invention may contain a conductive additive. Examples of conductive additives include carbon materials such as graphite, carbon black, Ketjenblack, acetylene black, vapor-grown carbon fibers (VGCF), carbon nanotubes, carbon nanohorns, and graphene, as well as conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene. These conductive additives can be used individually or in combination of two or more.

[0067] The content of the conductive additive is not particularly limited, but is preferably 0.1 to 5.0% by mass, and more preferably 0.5 to 3.0% by mass, in the composition. By setting the content of the conductive additive within the above range, good electrical conductivity can be obtained.

[0068] The electrode composition of the present invention may contain a second additive other than the secondary battery electrode additive described above. Specifically, this includes water, hydroxyl group-containing compounds, and compounds containing a nitrogen atom and a carbonyl structure. When water is added, it is thought that the water can dissolve alkaline impurities, thus promoting the neutralization reaction caused by boron-based additives. Hydroxyl group-containing compounds can reversibly coordinate to boron atoms, and the coordinated boron atoms are thought to be able to form salts with protons and lithium ions. This is expected to lead to the formation of a film with lithium ion transport properties. Specific examples of compounds containing hydroxyl groups include trimethylolmethane, trimethylolethane, trimethylolpropane, glycerin, mannitol, pentaerythritol, dipentaerythritol, polyvinyl alcohol and its derivatives, and polyvinyl alcohol copolymers and their derivatives. Trimethylolethane, mannitol, polyvinyl alcohol and its derivatives, and polyvinyl alcohol copolymers and their derivatives are particularly preferred, and polyvinyl alcohol and its derivatives, and polyvinyl alcohol copolymers and their derivatives are more preferred. Specific examples of compounds containing a nitrogen atom and a carbonyl structure include iminodiacetic acid, N-(2-hydroxyethyl)iminodiacetic acid, N-methyliminodiacetic acid, nitrilotriacetic acid, N,N-di(2-hydroxyethyl)glycymbicine, 1-methyl-4-piperidone, 1-ethyl-4-piperidone, and polyvinylpyrrolidone. In particular, N-methyliminodiacetic acid and polyvinylpyrrolidone are preferred, and polyvinylpyrrolidone is more preferred. The second additive described above can be used individually or in combination of two or more types.

[0069] The content of the second additive described above is not particularly limited, but is preferably 0.01 to 10.0% by mass, more preferably 0.01 to 5.0% by mass, even more preferably 0.01 to 1.0% by mass, even more preferably 0.01 to 0.8% by mass, and most preferably 0.01 to 0.45% by mass. Furthermore, its content is preferably 0.02 to 40, and more preferably 0.04 to 20, in terms of mass ratio with respect to the secondary battery electrode additive 1.

[0070] electric Extreme Group Solvents can also be used in the preparation of the product. The solvent is not particularly limited as long as it is conventionally used in the preparation of electrode compositions, for example, water; ethers such as tetrahydrofuran (THF), diethyl ether, and 1,2-dimethoxyethane (DME); halogenated hydrocarbons such as methylene chloride, chloroform, and 1,2-dichloroethane; amides such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP); ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and t-butanol. Examples of solvents include: coals; aliphatic hydrocarbons such as n-heptane, n-hexane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; glycol ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; glycols such as ethylene glycol and propylene glycol; carbonates such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; and organic solvents such as γ-butyrolactone, dimethyl sulfoxide (DMSO), dioxolane, and sulfolane. These solvents can be used individually or in combination of two or more.

[0071] When using the above binders, they may be dissolved in these solvents as needed before use. Suitable solvents in this case include water, NMP, DMSO, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, THF, dioxolane, sulfolane, DMF, DMAc, etc., and can be appropriately selected depending on the type of binder. However, NMP is suitable for non-water-soluble binders such as PVdF, and water is suitable for water-soluble binders such as PAA.

[0072] The solid content concentration of the electrode composition of the present invention is set appropriately considering the coating properties of the composition and the thickness of the thin film to be formed, but is usually about 50 to 90% by mass for the positive electrode, preferably about 55 to 85% by mass, and more preferably about 60 to 80% by mass. For the negative electrode, it is about 30 to 70% by mass, preferably about 30 to 65% by mass, and more preferably about 35 to 60% by mass. The solid content refers to components other than the solvent that make up the composition.

[0073] The electrode composition of the present invention can be obtained by mixing the above-mentioned components while heating them at a predetermined temperature. Reflux may also be performed during heating. If the composition contains optional components other than the additives and active material of the present invention, the additives and active material may be mixed together with the optional components, or they may be mixed beforehand and then mixed with the optional components. In either case, the surface of the active material can be coated with the additive, allowing the effects of the present invention to be fully realized.

[0074] In the present invention, when manufacturing the electrode composition described above, from the viewpoint of environmental impact, process cost, and safety, the maximum temperature reached during preparation is preferably 60 to 200°C, more preferably 60 to 150°C, even more preferably 60 to 130°C, with an upper limit of less than 130°C, for example, 60 to 125°C being even more preferable.

[0075] The electrode for a secondary battery of the present invention comprises an active material layer (thin film) made of the electrode composition described above on at least one surface of a substrate which is a current collector. When forming an active material layer on a substrate, methods for forming the active material layer include a method of pressure molding an electrode composition prepared without using a solvent onto the substrate (dry method), or a method of preparing an electrode composition using a solvent, coating it onto the substrate, and drying it (wet method). These methods are not particularly limited, and various conventionally known methods can be used. For example, wet methods include various printing methods such as offset printing and screen printing, as well as blade coating, dip coating, spin coating, bar coating, slit coating, inkjet, and die coating.

[0076] Also , dry When drying, either natural drying or heat drying is acceptable, but heat drying is preferred from the viewpoint of manufacturing efficiency. When heat drying is performed, the temperature is preferably around 50 to 400°C, and more preferably around 70 to 150°C.

[0077] Examples of substrates used for the electrodes mentioned above include metal substrates such as platinum, gold, iron, stainless steel, copper, aluminum, and lithium; alloy substrates made from any combination of these metals; oxide substrates such as indium tin oxide (ITO), indium zinc oxide (IZO), and antimony tin oxide (ATO); or carbon substrates such as glassy carbon, pyroretic graphite, and carbon felt. The thickness of the substrate is not particularly limited, but in the present invention, 1 to 100 μm is preferred.

[0078] The thickness of the active material layer (thin film) is not particularly limited, but is preferably about 0.01 to 1,000 μm, and more preferably about 5 to 300 μm. When the thin film is used as an electrode on its own, its thickness is preferably 10 μm or more.

[0079] The electrodes may be pressed as needed. While any commonly used pressing method can be employed, die pressing or roll pressing methods are particularly preferred. The pressing pressure is not particularly limited, but is preferably 1 kN / cm or higher, 2 kN / cm or higher, and more preferably 5 kN / cm or higher. Furthermore, the upper limit of the above pressing pressure is not particularly limited, but is preferably 50 kN / cm or lower.

[0080] Furthermore, in the electrode (positive electrode) of the secondary battery after charging and discharging, the intensity ratio ([CF] / [LiF]) of the CF peak (686±1.25eV) to the LiF peak (683.5±1.25eV), determined by XPS measurement (normalized with the CC-derived peak of C1s as 284eV), is preferably 3.0 or higher, and more preferably 4.5 or higher. The upper limit of the above intensity ratio is not particularly limited, but is preferably 10.0 or lower, and more preferably 6.0 or lower.

[0081] The secondary battery of the present invention is equipped with the electrodes described above, and more specifically, is configured to include at least one pair of positive and negative electrodes, a separator interposed between these electrodes, and an electrolyte, wherein at least one of the positive and negative electrodes is made of the electrodes described above. Other components of the battery element may be appropriately selected from those that are conventionally known.

[0082] Examples of materials used in the above-mentioned separators include glass fibers, cellulose, porous polyolefins, polyamides, and polyesters.

[0083] The electrolyte may be either a liquid or a solid, and may be either aqueous or non-aqueous. However, from the viewpoint of easily achieving sufficient performance for practical use, an electrolyte solution composed of an electrolyte salt, which is the main component of ion conduction, and a solvent can be preferably used.

[0084] Examples of the above electrolyte salts include LiPF6, LiBF4, and LiN(SO2F). 2、 Examples include lithium salts such as LiN(C2F5SO2)2, LiAsF6, LiSbF6, LiAlF4, LiGaF4, LiInF4, LiClO4, LiN(CF3SO2)2, LiCF3SO3, LiSiF6, LiN(CF3SO2), (C4F9SO2), metal iodides such as LiI, NaI, KI, CsI, and CaI2, iodide salts of quaternary imidazolium compounds, iodide salts and perchlorates of tetraalkylammonium compounds, and metal bromides such as LiBr, NaBr, KBr, CsBr, and CaBr2. These electrolyte salts can be used individually or in combination of two or more.

[0085] The solvents mentioned above are not particularly limited, as long as they do not cause corrosion or decomposition of the materials constituting the battery, thereby degrading its performance, and do not dissolve the electrolyte salts. For example, non-aqueous solvents that can be used include cyclic esters such as ethylene carbonate, propylene carbonate, butylene carbonate, and γ-butyrolactone; ethers such as tetrahydrofuran and dimethoxyethane; chain esters such as methyl acetate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and nitriles such as acetonitrile. These solvents can be used individually or in combination of two or more.

[0086] Furthermore, inorganic solid electrolytes such as sulfide-based solid electrolytes and oxide-based solid electrolytes, and organic solid electrolytes such as polymer-based electrolytes can be suitably used as the solid electrolyte. By using these solid electrolytes, an all-solid-state battery that does not use an electrolyte solution can be obtained.

[0087] The above sulfide-based solid electrolyte is a Li2S-SiS2-lithium compound (where the lithium compound is Li3PO4). 4、 (At least one selected from the group consisting of LiI and Li4SiO4) 、 Li2S-P2O 5、 Li2S-B2S 5、 Examples include thiolysicone-based materials such as Li2S-P2S5-GeS2.

[0088] As the above oxide-based solid electrolyte, Li5La3M2O is an oxide with a garnet-type structure. 12 (M=Nb,Ta) or Li7La3Zr2O 12 , oxyacid compounds based on the γ-Li3PO4 structure, collectively known as LISICON, perovskite type, Li collectively known as LIPON 3.3 PO 3.8 N 0.22 Examples include sodium / alumina. Examples of the polymeric solid electrolytes mentioned above include polyethylene oxide materials and polymer compounds obtained by polymerizing or copolymerizing monomers such as hexafluoropropylene, tetrafluoroethylene, trifluoroethylene, ethylene, propylene, acrylonitrile, vinylidene chloride, acrylic acid, methacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, styrene, and vinylidene fluoride. The polymeric solid electrolytes may also contain supporting salts and plasticizers.

[0089] Examples of supporting salts included in the above polymer solid electrolyte include lithium (fluorosulfonylimide), and examples of plasticizers include succinonitrile.

[0090] Batteries manufactured using the electrode composition of the present invention exhibit superior cycle characteristics and rate characteristics compared to general secondary batteries.

[0091] The form of the secondary battery and the type of electrolyte are not particularly limited; any form such as lithium-ion batteries, nickel-metal hydride batteries, manganese batteries, or air batteries may be used, but lithium-ion batteries are preferred. The lamination method and production method are also not particularly limited.

[0092] When applied to a coin-type battery, the secondary battery electrode of the present invention described above can be punched out into a predetermined disc shape and used. For example, a lithium-ion secondary battery can be manufactured by placing one electrode on a lid to which a washer and spacer of the coin cell are welded, placing a separator of the same shape impregnated with electrolyte on top of it, then placing the secondary battery electrode of the present invention on top with the active material layer facing downwards, placing a case and gasket on top, and sealing it with a coin cell crimping machine. [Examples]

[0093] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The apparatus used is as follows. (1) Homodispersion (mixing of electrode slurry) TK Robomix (with Homodisper 2.5 type (φ32)) manufactured by Primix Co., Ltd. (2) Thin film swirling high-speed mixer (for mixing electrode slurry) Primix Co., Ltd., Filmix Model 40 (3) Roll press machine (compression of electrodes) SA-602, manufactured by Takumi Giken Co., Ltd. (4) Dry Booth Manufactured by Nippon Spindle Manufacturing Co., Ltd. (5) Adhesion and film peeling analysis device (adhesion force measurement) VERSATILE PEEL ANALYZER VPA-3 manufactured by Kyowa Interface Science Co., Ltd. (6) Charge / discharge measuring device TOSCAT-3100, manufactured by Toyo Systems Co., Ltd. Temperature: room temperature (7) Impedance measuring device PARSTAT2273, manufactured by Princeton Applied Research. AC Amplitude: 10mVrms Frequency: 200kHz~100mHz Temperature: room temperature (8) XPS measurement ULVAC-PHI, Inc. PHI 5000 VersaProbe II Measurement area: 1,000 μmφ Neutralization ON (electron gun only) Number of measurements: 2 X-ray: Al Ka ​​1486.6eV (25W, 15kV) Analyzer: Photoelectron Take off angle:45deg from sample plane

[0094] [1] Synthesis of additives for secondary battery electrodes [Example 1-1] 6.10 g (0.05 mol) of phenylboronic acid (manufactured by Tokyo Chemical Industry Co., Ltd., the same applies hereafter), 6.00 g (0.05 mol) of trimethylolethane (manufactured by Tokyo Chemical Industry Co., Ltd.), and 100 g of toluene (manufactured by Kanto Chemical Co., Ltd., the same applies hereafter) were placed in a flask along with a stirring bar. A Dean Stark tube and a condenser were connected to this flask and it was immersed in an oil bath set to 130°C. Phenylboronic acid and trimethylolethane were reacted by refluxing for 4 hours, while removing water and toluene accumulated in the Dean Stark tube as needed. The solvent was removed from the reaction solution under reduced pressure to obtain a boronic acid derivative represented by the following formula (8-1).

[0095] [ka]

[0096] [Examples 1-2] 6.18 g (0.03 mol) of the boronic acid derivative represented by formula (8-1) above, 0.65 g (0.0027 mol) of lithium hydroxide (manufactured by Kishida Chemical Co., Ltd.), and 61.45 g of toluene (manufactured by Kanto Chemical Co., Ltd.) were placed in a flask along with a stirring bar. A Dean Stark tube and a condenser were connected to this flask and it was immersed in an oil bath set to 130°C. The boronic acid derivative represented by formula (8-1) and lithium hydroxide were reacted under reflux for 4 hours, while removing water and toluene accumulated in the Dean Stark tube as needed. The solvent was removed from the reaction mixture under reduced pressure to obtain the triol borate lithium salt represented by formula (8-6) below.

[0097] [ka]

[0098] [2] Preparation of the positive electrode composition (electrode slurry) [Example 2-1] In the drying booth, lithium nickel manganese cobalt oxide (NCM, LiNi) is used as the active material. 0.8 Co 0.1 Mn 0.140.28 g of O2 (manufactured by LinYi Gelon LIB Co., Ltd., S-800, the same applies hereafter), 12.00 g of a 7% by mass solution (7%) of polyvinylidene fluoride (PVdF, manufactured by SOLVAY, Solef-5140, the same applies hereafter) in NMP (special grade) (manufactured by Junsei Chemical, the same applies hereafter) as a binder, 0.84 g of acetylene black (AB, Denka Black, manufactured by Denka Co., Ltd., the same applies hereafter) as a conductive additive, 1.4 g of a 3% by mass solution (3%) of the secondary battery electrode additive synthesized in Example 1-1, and 5.48 g of NMP (special grade) were mixed in a homodisper at 8,000 rpm for 1 minute. Next, an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)) was prepared by performing a mixing process twice at a peripheral speed of 20 m / s for 30 seconds using a thin-film swirling high-speed mixer.

[0099] [Example 2-2] In a drying booth, 40.11 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as a conductive additive, 7.0 g of NMP (special grade) solution of the secondary battery electrode additive synthesized in Example 1-1 (3% by mass), and 0.05 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.5:2:2:0.5 (mass ratio)).

[0100] [Examples 2-3] In a drying booth, 40.11 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as a conductive additive, 7.0 g of NMP (special grade) solution of the secondary battery electrode additive synthesized in Example 1-2 (3% by mass), and 0.05 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0101] [Comparative Example 2-1] In a drying booth, 40.32 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) polyvinylidene fluoride solution (7% by mass) as the binder, and 0.84 g of acetylene black and 6.84 g of NMP (special grade) as conductive additives were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additives = 96:2:2:0 (mass ratio)).

[0102] [Comparative Example 2-2] In a drying booth, 40.11 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 4.21 g of NMP (special grade) solution of p-toluenesulfonyl isocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) (5% by mass) as additives, and 2.85 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Next, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.5:2:2:0.5 (mass ratio)).

[0103] [Comparative Example 2-3] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) polyvinylidene fluoride solution (7% by mass) as the binder, 0.84 g of acetylene black as a conductive additive, 0.042 g of acetylene black as an additive, and 6.84 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0104] [Comparative Example 2-4] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 1.4 g of NMP (special grade) solution of trimethyl borate (manufactured by Kishida Chemical Co., Ltd.) (3% by mass) as the additive, and 5.48 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Next, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0105] [Comparative Example 2-5] In a drying booth, 40.28 g of lithium nickel manganese cobaltate as the active material, 12.00 g of NMP (special grade) polyvinylidene fluoride solution (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 1.4 g of NMP (special grade) phenylboronic acid solution (3% by mass) as the additive, and 5.48 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0106] [Comparative Example 2-6] In a drying booth, 40.11 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) polyvinylidene fluoride solution (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 7.0 g of NMP (special grade) phenylboronic acid solution (3% by mass) as the additive, and 0.05 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.5:2:2:0.5 (mass ratio)).

[0107] [Comparative Example 2-7] In a drying booth, 40.28 g of lithium nickel manganese cobaltate as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 1.4 g of NMP (special grade) solution of phosphorous acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (3% by mass) as additives, and 5.48 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Next, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0108] [Comparative Example 2-8] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 1.4 g of NMP (special grade) solution of trimethylolethane (manufactured by Tokyo Chemical Industry Co., Ltd.) (3% by mass) as the additive, and 5.48 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Next, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0109] [Comparative Example 2-9] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) polyvinylidene fluoride solution (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 0.042 g of lithium metaborate (LiBO2, manufactured by Kishida Chemical Co., Ltd.) and 6.84 g of NMP (special grade) as additives were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0110] [Comparative Example 2-10] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, and 1.4 g of NMP (special grade) solution of triethylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd.) (3% by mass) and 5.48 g of NMP (special grade) as additives were mixed in a homodisperser at 8,000 rpm for 1 minute. Next, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0111] [Comparative Example 2-11] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as the binder, 0.84 g of acetylene black as the conductive additive, 1.4 g of NMP (special grade) solution of glycerol (manufactured by Tokyo Chemical Industry Co., Ltd.) (3% by mass) as the additive, and 5.48 g of NMP (special grade) were mixed in a homodisperser at 8,000 rpm for 1 minute. Next, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0112] [3] Fabrication of positive electrode and evaluation of adhesion strength [Examples 3-1 to 3-3, Comparative Examples 3-1 to 3-11] The electrode slurries obtained in Examples 2-1 to 2-3 and Comparative Examples 2-1 to 2-11 were uniformly applied to aluminum foil (15 μm thick, manufactured by UACJ Corporation), which served as the current collector, using a doctor blade. The mixture was dried at 80°C for 30 minutes to form an active material layer, and then compressed using a roll press to produce the electrode (positive electrode). The basis weight of the electrode was 30 ± 1 mg / cm². 2 The coating thickness was adjusted to achieve the desired result. Table 1 summarizes the electrode slurry, additives, and composition ratios of the electrode slurry used in each example and comparative example.

[0113] <Measuring adhesion strength> The electrodes prepared in the examples and comparative examples were cut to a width of 25 mm, and 20 mm wide double-sided tape was attached to the active material layer coated surface and fixed onto a glass substrate. This was then fixed to an adhesion / film peel analysis device, and a peel test was performed at a peel angle of 90° and a peel speed of 100 mm / min to measure the adhesion strength. The results are shown in Table 1. The maximum temperature reached during the preparation of each composition is also indicated.

[0114] [Table 1]

[0115] As shown in Table 1, it was confirmed that forming an active material layer using an electrode slurry containing the secondary battery electrode additive according to the present invention improves the adhesion between the current collector and the active material layer. This is expected to improve handling during the battery assembly process and expand the design specifications of the battery.

[0116] [4] Battery fabrication and characterization [Manufacturing Example 1] Fabrication of a negative electrode 23.49 g of graphite (manufactured by Nippon Graphite Industries Co., Ltd., CGB10) as the active material, 0.5 g of acetylene black as a conductive additive, 0.5 g of carboxymethylcellulose (CMC, manufactured by AS ONE Corporation) as a binder, 1.55 g of an aqueous emulsion solution (48.5% by mass) containing styrene-butadiene copolymer (SBR) (manufactured by JSR Corporation, TRD2001), and 26.46 g of pure water were mixed in a homodisper at 8,000 rpm for 5 minutes. Then, using a thin-film swirling high-speed mixer, the mixture was mixed twice at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 47.6% by mass, graphite:CMC:SBR:AB = 94:2:3:2 (mass ratio)). The obtained electrode slurry was uniformly applied to electrolytic copper foil (10 μm thick, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., the same applies hereafter) using a doctor blade, dried at 80°C for 30 minutes to form an active material layer, and then compressed with a roll press to produce a negative electrode. The basis weight of the electrode was 18 ± 1 mg / cm².2 The coating thickness was adjusted to achieve this result.

[0117] [Examples 4-1 to 4-3, Comparative Examples 4-1 to 4-11] Four 10mm diameter disc-shaped electrodes were punched out from the positive electrodes obtained in Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-11. The mass of the positive electrode layer (the mass of the punched-out electrode minus the mass of the uncoated portion punched out to a diameter of 10mm) and the electrode layer thickness (the thickness of the punched-out electrode minus the thickness of the substrate) were measured, and after vacuum drying at 120°C for 15 hours, they were transferred to a drying booth.

[0118] From the negative electrode obtained in Manufacturing Example 1, four 13mm diameter disc-shaped electrodes were punched out. The mass of the negative electrode layer (the mass of the punched-out electrodes minus the mass of the uncoated portion punched out to a diameter of 10mm) and the electrode layer thickness (the thickness of the punched-out electrodes minus the thickness of the substrate) were measured, and after vacuum drying at 120°C for 15 hours, they were transferred to a drying booth.

[0119] A negative electrode was placed on the lid of a 2032 type coin cell (manufactured by Hosen Co., Ltd., hereafter the same), which had a washer and spacer welded to it. On top of this, a 16mm diameter separator (glass fiber circular filter paper GF / F, manufactured by WATT MANN CO., LTD, hereafter the same) was placed, which had been impregnated with a mixture of 20g of electrolyte (ethylene carbonate:diethyl carbonate = 1:1 (volume ratio) with lithium hexafluorophosphate dissolved at 1M, manufactured by Kishida Chemical Co., Ltd., hereafter the same) and 0.4g of fluoroethylene carbonate (manufactured by Kishida Chemical Co., Ltd., hereafter the same). The positive electrode was then placed on top of that, with the side coated with the active material facing downwards. After adding one drop of electrolyte, the case with the washer and spacer welded to it and the gasket were placed on top, and it was sealed using a coin cell crimping machine. After standing for 24 hours, four secondary batteries were prepared for each of Examples 4-1 to 4-3 and Comparative Examples 4-1 to 4-11.

[0120] <Charge / Discharge Evaluation> The characteristics of the test secondary batteries prepared in the examples and comparative examples were evaluated. To evaluate the effect of additives on the battery in the positive electrode, charge-discharge tests were performed using a charge-discharge measuring device in the order of battery aging, load characteristics evaluation, and cycle characteristics evaluation, under the conditions shown in Table 2.

[0121] [Table 2]

[0122] Table 3 summarizes the volumes for the first and 100th cycles of the cycle test.

[0123] <Impedance Measurement> The characteristics of the test secondary batteries prepared in the examples and comparative examples were evaluated. Impedance measurements were performed to evaluate the effect of additives in the positive electrode on the battery.

[0124] Table 3 summarizes the resistance values ​​at 100 mHz obtained from impedance measurements in steps 3 and 8.

[0125] [Table 3]

[0126] As shown in Table 3, the electrode slurry containing the additive for secondary battery electrodes according to the present invention is formed using the electrode slurry. Ta Secondary batteries using a positive electrode with an active material layer exhibit superior capacity, resistance, and cycle characteristics.

[0127] <XPS measurement> Mitsuru Evaluation of the positive electrode after discharge Coin cells from Examples 4-1 to 4-3 and Comparative Examples 4-1 to 4-11 were used, prepared using the positive electrodes fabricated in Examples 3-1 to 3-3 and Comparative Examples 3-1 to 3-11. After the charge-discharge test described above, each battery was discharged to 3V at 0.3C-CC, followed by CV discharge at 3V with a cutoff current of 0.03mA. The battery was then disassembled and the positive electrode was removed. The positive electrode was cleaned with diethyl carbonate, dried, and then XPS measurement was performed under the above conditions. Based on the measurement results, the intensity ratio of the peak originating from CF bonding (685-687eV), obtained by normalizing the CC-derived peak position of C1s to 284eV, and the intensity ratio of the peak originating from LiF (682.5-684.5) was calculated. The results are shown in Table 4.

[0128] [Table 4]

[0129] [5] Preparation of negative electrode composition (electrode slurry) [Example 5-1] As the active material, 6.02 g of silicon monoxide (SiO, manufactured by Osaka Titanium Technologies Co., Ltd., the same applies hereafter), 12.79 g of spheroidized natural graphite (Gr, manufactured by Nippon Graphite Industries Co., Ltd., CGB-10, the same applies hereafter), 14.46 g of NMP (special grade) solution of polyvinylidene fluoride (7% by mass) as a binder, 0.41 g of acetylene black as a conductive additive, 0.68 g of NMP (special grade) solution of secondary battery electrode additive (3% by mass) synthesized in Example 1-1, and 10.64 g of NMP (special grade) were mixed twice at 8,000 rpm for 30 seconds each using a homodisper. Next, an electrode slurry (solid content concentration 45% by mass, SiO / Gr / PVdF / AB / additives = 29.73 / 63.17 / 5.0 / 2.0 / 0.1 (mass ratio)) was prepared by performing a mixing process twice at a peripheral speed of 20 m / s for 30 seconds using a thin-film swirling high-speed mixer.

[0130] [Example 5-2] As the active material, 5.99 g of silicon monoxide, 12.74 g of spheroidized natural graphite, 14.46 g of NMP (special grade) solution (7 mass%) of polyvinylidene fluoride as a binder, 0.41 g of acetylene black as a conductive additive, 3.38 g of NMP (special grade) solution (3 mass%) of the secondary battery electrode additive synthesized in Example 1-1, and 8.02 g of NMP (special grade) were mixed twice at 8,000 rpm for 30 seconds each using a homodisperser. Then, the mixture was mixed twice at a peripheral speed of 20 m / s for 30 seconds each using a thin-film swirling high-speed mixer to prepare an electrode slurry (solid content concentration 45 mass%, SiO / Gr / PVdF / AB / additive = 29.60 / 62.90 / 5.0 / 2.0 / 0.5 (mass ratio)).

[0131] [Comparative Example 5-1] As the active material, 6.03 g of silicon monoxide and 12.81 g of spheroidized natural graphite, along with 14.46 g of a 7% by mass NMP (special grade) solution of polyvinylidene fluoride as a binder, and 0.41 g of acetylene black and 11.30 g of NMP (special grade) as conductive additives, were mixed twice at 8,000 rpm for 30 seconds each using a homodisperser. Subsequently, the mixture was mixed twice at a peripheral speed of 20 m / s for 30 seconds each using a thin-film swirling high-speed mixer to prepare an electrode slurry (solid content concentration 45% by mass, SiO / Gr / PVdF / AB / additives = 29.76 / 63.24 / 5.0 / 2.0 / 0 (mass ratio)).

[0132] [6] Fabrication of the negative electrode [Example 6-1~ 6-2 Comparative Example 6-1] The electrode slurries obtained in Examples 5-1 to 5-2 and Comparative Example 5-1 were uniformly applied to electrolytic copper foil, which served as the current collector, using a doctor blade. The mixture was dried at 80°C for 30 minutes to form an active material layer, and then compressed using a roll press to produce electrodes. The basis weight of the electrodes was 5.5 ± 0.2 mg / cm³. 2 The coating thickness was adjusted to achieve the desired result. Table 5 summarizes the electrode slurry, additives, and composition ratios used in each example and comparative example. The highest temperature reached during the preparation of each composition is also indicated.

[0133] [Table 5]

[0134] [7] Battery Fabrication and Characterization - 2 [Manufacturing Example 2] Fabrication of a positive electrode In a drying booth, 40.32 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (special grade) polyvinylidene fluoride solution (7% by mass) as the binder, and 0.84 g of acetylene black and 6.84 g of NMP as conductive additives were mixed in a homodisperser at 8,000 rpm for 1 minute. Next, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additives = 96:2:2:0 (mass ratio)). The obtained electrode slurry was uniformly applied to aluminum foil (15 μm thick, manufactured by UACJ Corporation) using a doctor blade, dried at 80°C for 30 minutes to form an active material layer, and then compressed with a roll press to prepare a positive electrode. The basis weight of the electrode was 21.3 ± 0.3 mg / cm². 2 The coating thickness was adjusted to achieve this result.

[0135] [Examples 7-1 to 7-2, Comparative Example 7-1] From the positive electrode obtained in Manufacturing Example 2, four 10mm diameter disc-shaped electrodes were punched out. The mass of the positive electrode layer (the mass of the punched-out electrodes minus the mass of the uncoated portion punched out to a diameter of 10mm) and the electrode layer thickness (the thickness of the punched-out electrodes minus the thickness of the substrate) were measured, and after vacuum drying at 120°C for 15 hours, they were transferred to a drying booth.

[0136] Four 13mm diameter disc-shaped electrodes were punched out from the negative electrodes obtained in Examples 6-1 to 6-2 and Comparative Example 6-1. The mass of the negative electrode layer (the mass of the punched-out electrode minus the mass of the uncoated portion punched out to a diameter of 10mm) and the electrode layer thickness (the thickness of the punched-out electrode minus the thickness of the substrate) were measured, and after vacuum drying at 120°C for 15 hours, they were transferred to a drying booth.

[0137] A negative electrode was placed on the lid of a 2032 type coin cell, which had a washer and spacer welded to it. A 16mm diameter separator, impregnated with a mixture of 20g of electrolyte and 0.4g of fluoroethylene carbonate, was then placed on top. The positive electrode was then placed on top of that, with the side coated with the active material facing downwards. After adding one drop of electrolyte, the case with the washer and spacer welded to it and the gasket were placed on top and sealed with a coin cell crimping machine. After standing for 24 hours, four test secondary batteries were prepared for each of Examples 7-1 to 7-2 and Comparative Example 7-1.

[0138] The fabricated test secondary batteries were subjected to charge-discharge tests using the same method as described above. The results are shown in Table 6.

[0139] [Table 6]

[0140] As shown in Table 6, the electrode slurry containing the additive for secondary battery electrodes according to the present invention is formed using the electrode slurry. Ta Secondary batteries using a negative electrode with an active material layer exhibit low resistance and excellent cycle characteristics.

[0141] [8] Synthesis of additives for secondary battery electrodes - 2 [Example 8-1] 7.32 g of phenylboronic acid, 5.47 g of D-mannitol (manufactured by Tokyo Chemical Industry Co., Ltd.), and 63.9 g of toluene were placed in a flask along with a stirring bar. A Dean Stark tube and a condenser were connected to this flask and it was immersed in an oil bath set to 130°C. The mixture was refluxed for 4 hours, with the water and toluene accumulated in the Dean Stark tube being removed as needed, to react the phenylboronic acid and D-mannitol. The solvent was removed from the reaction mixture under reduced pressure to obtain a boronic acid derivative represented by the following formula (8-5).

[0142] [ka]

[0143] [Example 8-2] 1.76 g of polyvinyl alcohol (Mw 61,000, manufactured by Sigma-Aldrich, the same applies hereafter) and 14.1 g of DMSO were placed in a flask with a stirring bar. This was heated to dissolve the polyvinyl alcohol, and then 1.95 g of phenylboronic acid and 42.24 g of toluene were added. A Dean Stark tube and a condenser were connected to the flask and it was immersed in an oil bath set to 140°C. The reaction between polyvinyl alcohol and phenylboronic acid was carried out under reflux for 4 hours, while removing water and toluene accumulated in the Dean Stark tube as needed. The solvent was removed from the reaction mixture under reduced pressure to obtain a boronic acid derivative represented by the following formula (9-2).

[0144] [ka]

[0145] [Example 8-3] 3.52 g of polyvinyl alcohol and 24.6 g of NMP (special grade) were placed in a flask with a stirring bar. This was heated to dissolve the polyvinyl alcohol, and then 3.8 g of phenylboronic acid dissolved in 5.28 g of NMP (special grade) was added. Next, 0.007 g of 1,4-phenylenediboronic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) dissolved in 0.53 g of NMP (special grade) was added. A Dean Stark tube and a condenser were connected to the flask and it was immersed in an oil bath set to 140°C. While removing water and NMP accumulated in the Dean Stark tube as needed, reflux was performed for 4 hours to obtain an NMP solution containing a boronic acid derivative represented by the following formula (9-3).

[0146] [ka]

[0147] [9] Preparation of the composition for the positive electrode (electrode slurry) - 2 [Example 9-1] In a drying booth, 40.28g of lithium nickel manganese cobalt oxide was used as the active material, and NMP (dehydrated polyvinylidene fluoride) (manufactured by Kishida Chemical Co., Ltd., hereafter the same) was used as the binder. ) melt 12.00 g of liquid (7% by mass), 0.84 g of acetylene black as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive synthesized in Example 1-1, and 6.04 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0148] [Example 9-2] In a drying booth, 40.22 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as a binder, 0.84 g of acetylene black as a conductive additive, 2.10 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive synthesized in Example 1-1, and 4.85 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.75:2:2:0.25 (mass ratio)).

[0149] [Example 9-3] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as the binder, 0.84 g of acetylene black as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive synthesized in Example 8-1, and 6.04 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0150] [Example 9-4] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP solution (7% by mass) of polyvinylidene fluoride as a binder, 0.84 g of acetylene black as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive synthesized in Example 8-2, and 6.04 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0151] [Example 9-5] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of an NMP (dehydrated) solution of polyvinylidene fluoride (7% by mass) as a binder, 0.84 g of acetylene black as a conductive additive, 0.84 g of the NMP solution of the secondary battery electrode additive synthesized in Example 8-3 diluted with NMP (dehydrated) to 5% by mass, and 6.04 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Next, the electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)) was prepared by performing two mixing processes at a peripheral speed of 20 m / s for 30 seconds each using a thin-film swirling high-speed mixer.

[0152] [Comparative Example 8-1] In a drying booth, 40.32 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as the binder, and 0.84 g of acetylene black and 6.84 g of NMP as conductive additives were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additives = 96:2:2:0 (mass ratio)).

[0153] [Comparative Example 8-2] In a drying booth, 40.28 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as the binder, 0.84 g of acetylene black as a conductive additive, 0.042 g of acetylene black as an additive, and 6.84 g of NMP (dehydrated) were mixed in a homodisperser at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive = 95.9:2:2:0.1 (mass ratio)).

[0154]

[10] Fabrication of positive electrode and evaluation of adhesion force - 2 [Examples 10-1 to 10-5, Comparative Examples 9-1 to 9-2] Using the electrode slurries obtained in Examples 9-1 to 9-5 and Comparative Examples 8-1 to 8-2, electrodes (positive electrodes) were prepared in the same manner as in Example 3-1. However, the basis weight of the electrodes was 21.8 ± 0.4 mg / cm³. 2 The coating thickness was adjusted to achieve the desired result. Table 7 summarizes the electrode slurry, additives, and composition ratios of the electrode slurry used in each example and comparative example.

[0155] The electrodes prepared in the examples and comparative examples were subjected to peel tests using the same method as described above, and the adhesion strength was measured. The results are shown in Table 7. The maximum temperature reached during the preparation of each composition is also indicated.

[0156] [Table 7]

[0157]

[11] Battery fabrication and characterization - 3 [Manufacturing Example 3] Fabrication of a negative electrode An electrode plate was purchased from Hachiyama Co., Ltd. and used, in which an active material layer was formed on a copper foil (thickness 10 μm) containing artificial graphite as the active material and carboxymethylcellulose (CMC) and styrene-butadiene copolymer (SBR) as binders, with the ratio of artificial graphite:CMC:SBR = 98:1:1 (mass ratio). The basis weight of the above active material layer was 14.5 mg / cm³. 2 The density is 1.45 g / cc.

[0158] [Examples 11-1 to 11-5, Comparative Examples 10-1 to 10-2] Using the positive electrodes obtained in Examples 10-1 to 10-5 and Comparative Examples 9-1 to 9-2, and the negative electrode from Manufacturing Example 3, four test secondary batteries were prepared in the same manner as in Example 4-1.

[0159] The fabricated test secondary batteries were subjected to charge-discharge tests using the same method as described above. The results are shown in Table 8.

[0160] [Table 8]

[0161] As shown in Table 8, the electrode slurry containing the additive for secondary battery electrodes according to the present invention is formed using the electrode slurry. Ta Secondary batteries using a positive electrode with an active material layer exhibit superior capacity, resistance, and cycle characteristics.

[0162]

[12] Preparation of the composition for the positive electrode (electrode slurry) - 3 [Example 12-1] In a drying booth, 40.24 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as a binder, 0.84 g of acetylene black as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive (additive A) synthesized in Example 1-1, 0.84 g of NMP (dehydrated) solution (5% by mass) of polyvinylpyrrolidone (additive B), and 5.24 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive A:additive B = 95.8:2:2:0.1:0.1 (mass ratio)).

[0163] [Example 12-2] In a drying booth, 40.24 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as a binder, 0.84 g of acetylene black as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive (additive A) synthesized in Example 1-1, 0.84 g of NMP (dehydrated) solution (5% by mass) of water (additive B), and 5.24 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive A:additive B = 95.8:2:2:0.1:0.1 (mass ratio)).

[0164] [Example 12-3] In a drying booth, 40.24 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as a binder, 0.84 g of acetylene black as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive (additive A) synthesized in Example 1-1, 0.84 g of NMP (dehydrated) solution (5% by mass) of trimethylolethane (additive B), and 5.24 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive A:additive B = 95.8:2:2:0.1:0.1 (mass ratio)).

[0165] [Example 12-4] In a drying booth, 40.24 g of lithium nickel manganese cobalt oxide as the active material, 12.00 g of NMP (dehydrated) solution (7% by mass) of polyvinylidene fluoride as a binder, 0.84 g of acetylene black as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive (additive A) synthesized in Example 1-1, 0.84 g of NMP (dehydrated) solution (5% by mass) of D-mannitol (additive B), and 5.24 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive A:additive B = 95.8:2:2:0.1:0.1 (mass ratio)).

[0166] [Example 12-5] In a drying booth, 40.24 g of lithium nickel manganese cobalt oxide was used as the active material, 12.00 g of NMP solution (7% by mass) of polyvinylidene fluoride was used as the binder, 0.84 g of acetylene black was used as a conductive additive, 0.84 g of NMP (dehydrated) solution (5% by mass) of the secondary battery electrode additive (additive A) synthesized in Example 1-1, 0.84 g of NMP (dehydrated) solution (5% by mass) of N-methyliminodiacetic acid (additive B), and 5.24 g of NMP (dehydrated) were mixed in a homodisper at 8,000 rpm for 1 minute. Then, two mixing processes were performed using a thin-film swirling high-speed mixer at a peripheral speed of 20 m / s for 30 seconds each to prepare an electrode slurry (solid content concentration 70% by mass, NCM:PVdF:AB:additive A:additive B = 95.8:2:2:0.1:0.1 (mass ratio)).

[0167]

[13] Fabrication of positive electrode and evaluation of adhesion force - 3 [Examples 13-1 to 13-5] Using the electrode slurries obtained in Examples 13-1 to 13-5, electrodes (positive electrodes) were prepared in the same manner as in Example 3-1. However, the basis weight of the electrodes was 21.8 ± 0.4 mg / cm³. 2The coating thickness was adjusted to achieve this. Table 9 summarizes the electrode slurries, additives, and composition ratios of the electrode slurries used in each example and comparative example.

[0168] For the electrodes prepared in the examples and comparative examples, a peel test was conducted in the same manner as described above, and the adhesion strength was measured. The results are shown in Table 9. For comparison, the results of the electrodes of Example 10-1 and Comparative Example 9-1 are also included in Table 9. Also, the maximum temperature reached during the preparation of each composition is included.

[0169]

Table 9

[0170]

[14] Fabrication and Characterization of Batteries - 4 [Examples 14-1 to 14-5] Using the positive electrodes obtained in Examples 13-1 to 13-5 and the negative electrode of Production Example 3 above, four test secondary batteries were fabricated each in the same manner as in Example 4-1.

[0171] For the fabricated test secondary batteries, a charge-discharge test was conducted in the same manner as described above. The results are shown in Table 10. For comparison, the results of the electrodes of Example 11-1 and Comparative Example 10-1 are also included in Table 10.

[0172]

Table 10

[0173] As shown in Table 10, it can be seen that the secondary battery using the positive electrode provided with the active material layer formed using the electrode slurry containing the additive for the secondary battery electrode according to the present invention has excellent capacity, resistance, and cycle characteristics. Ta ​

Claims

1. An additive for secondary battery electrodes consisting of a boronic acid derivative, The above boronic acid derivative is a reaction product of an arylboronic acid represented by the following formula (1) and a reactive compound having at least two reactive groups selected from the group consisting of a hydroxyl group, a carbonyl group, an isocyanate group, and an amino group. An additive for secondary battery electrodes, wherein the above-mentioned reactive compound is at least one selected from the group consisting of trimethylolmethane, trimethylolethane, trimethylolpropane, glycerin, mannitol, pentaerythritol, dipentaerythritol, diaminonaphthalene, phenylenediamine, N-methyliminodiacetic acid, oxalic acid, fumaric acid, phthalic acid, succinic acid, citric acid, isocitric acid, oxalosuccinic acid, oxaloacetic acid, aconitic acid, p-toluenesulfonyl isocyanate, chlorosulfonyl isocyanate, polyvinyl alcohol and its derivatives, and polyvinyl alcohol copolymer and its derivatives. 【Chemistry 1】 (In the formula, Ar represents an optionally substituted aryl group or an optionally substituted heteroaryl group.)

2. The additive for secondary battery electrodes according to claim 1, wherein the above Ar is a phenyl group which may have substituents.

3. The additive for secondary battery electrodes according to claim 1 or 2, wherein the arylboronic acid is represented by the following formula (2). 【Chemistry 2】 (In the formula, R 1 ~R 5 Each of these independently represents a hydrogen atom, an alkyl group, an ester group, a glycol chain, an alkoxy group, or a hydroxyl group.

4. The additive for secondary battery electrodes according to any one of claims 1 to 3, wherein the reactive compound has three or more of the above-mentioned reactive groups.

5. The additive for secondary battery electrodes according to claim 4, wherein the reactive compound has three or more hydroxyl groups.

6. The additive for secondary battery electrodes according to any one of claims 3 to 5, wherein the boronic acid derivative comprises a repeating unit represented by the following formula (5) or the following formula (6). 【Chemistry 4】 (In the formula, R 1 ~R 5 This expresses the same meaning as above, R 6 (This represents a hydrogen atom, a methyl group, or an ethyl group.)

7. The additive for secondary battery electrodes according to any one of claims 3 to 5, wherein the boronic acid derivative is represented by the following formula (7). 【Transformation 5】 (In the formula, R 1 ~R 5 This expresses the same meaning as above, R 6 (This represents a hydrogen atom, a methyl group, or an ethyl group.)

8. An additive for secondary battery electrodes comprising a boronic acid derivative, The above boronic acid derivative is an additive for secondary battery electrodes containing a repeating unit represented by the following formula (3) or the following formula (4). 【Transformation 6】 (In the formula, Ar represents an optionally substituted aryl group or an optionally substituted heteroaryl group, and R6 represents a hydrogen atom, a methyl group, or an ethyl group.)

9. An electrode composition comprising an additive for secondary battery electrodes according to any one of claims 1 to 8 and an active material.

10. The electrode composition according to claim 9, further comprising a second additive different from the secondary battery electrode additive described in any one of claims 1 to 8.

11. The electrode composition according to claim 10, wherein the second additive is at least one selected from the group consisting of water, hydroxyl group-containing compounds, and compounds containing a nitrogen atom and a carbonyl structure.

12. The electrode composition according to claim 10 or 11, wherein the second additive is at least one selected from the group consisting of polyvinylpyrrolidone, polyvinyl alcohol and its derivatives, and polyvinyl alcohol copolymer and its derivatives.

13. The electrode composition according to any one of claims 9 to 12, wherein the active material is an oxide containing Li and Ni, and the composition is for a positive electrode.

14. The electrode composition according to any one of claims 9 to 13, wherein the additive for secondary battery electrodes is contained in an amount of 0.01 to 10.0% by mass.

15. The electrode composition according to any one of claims 9 to 12, wherein the active material is at least one selected from the group consisting of graphite, Si, SiO, lithium titanate (LTO), and metallic Li, and is a composition for a negative electrode.

16. The electrode composition according to claim 15, wherein the additive for secondary battery electrodes is contained in an amount of 0.02 to 10.0% by mass.

17. An electrode for a secondary battery, comprising a current collector substrate and an active material layer formed on at least one surface of the current collector substrate, wherein the active material layer is formed of the electrode composition according to any one of claims 9 to 12.

18. A positive electrode for a secondary battery, comprising a current collector substrate and an active material layer formed on at least one surface of the current collector substrate, wherein the active material layer is formed of the electrode composition according to claim 13 or 14.

19. The positive electrode for a secondary battery according to claim 18, wherein, in the electrode of the secondary battery after charging and discharging, the intensity ratio ([C-F] / [LiF]) of the intensity of the C-F peak (686±1.25 eV) to the intensity of the LiF peak (683.5±1.25 eV), determined by XPS measurement (normalized with the C-C originating peak of C1s as 284 eV), is 3.0 or more.

20. A negative electrode for a secondary battery, comprising a current collector substrate and an active material layer formed on at least one surface of the current collector substrate, wherein the active material layer is formed of the electrode composition according to claim 15 or 16.

21. A secondary battery comprising at least one electrode selected from the group consisting of the electrode for secondary battery described in claim 17, the positive electrode for secondary battery described in claim 18 or 19, and the negative electrode for secondary battery described in claim 20.

22. The secondary battery according to claim 21, which is a lithium-ion secondary battery.

23. The secondary battery according to claim 21, which is an all-solid-state battery.

24. A method for producing an electrode composition comprising an additive for secondary battery electrodes and an active material according to any one of claims 1 to 8, A method for producing an electrode composition in which the maximum temperature reached during the preparation of the composition is 60 to 200°C.

25. A method for producing the electrode composition according to claim 24, wherein the maximum temperature that can be reached is 60 to 150°C.

26. A method for producing the electrode composition according to claim 25, wherein the maximum temperature that can be reached is 60 to 125°C.

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