JP2016009670A - Method for manufacturing nonaqueous secondary battery electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new manufacturing method of an electrode using polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid.SOLUTION: A method for manufacturing a nonaqueous secondary battery electrode includes the steps: a) preparing an electrode body having a current collector, an active material, and a binder; b) preparing a solution containing polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid; and c) bringing the electrode body into contact with the solution.

Description

  The present invention relates to a method for producing an electrode for a non-aqueous secondary battery.

  The number of products using non-aqueous secondary batteries continues to increase, and in general, non-aqueous secondary batteries are recognized as essential for portable devices such as mobile phones and notebook computers. Among non-aqueous secondary batteries, lithium ion secondary batteries are widely used because of their small size and large capacity. A lithium ion secondary battery includes a pair of electrodes, a positive electrode and a negative electrode, as essential components. Each electrode has an active material layer and a current collector to which the active material layer is bound. In general, the active material layer containing the active material contains a binder for securing the active material to the surface of the current collector.

  Polyacrylic acid, polymethacrylic acid and their derivatives are already known to be usable as binders because of their high binding properties, but they are also known to be inferior in strength. It was not common to use acrylic acid itself or polymethacrylic acid itself.

  For example, Patent Document 1 describes an electrode for a lithium ion secondary battery in which a polyacrylic acid lithium salt or a polyacrylic acid sodium salt is employed as a binder instead of polyacrylic acid itself.

  Patent Document 2 discloses not only polyacrylic acid as a binder, but also an electrode for a lithium ion secondary battery using polyacrylic acid and carboxymethylcellulose in combination as a binder, and polyacrylic acid as a binder. An electrode for a lithium ion secondary battery using polyethyleneimine and polyvinylidene fluoride in combination is described, and it is described that the polymer forms a crosslinked network by the above combination.

JP 2009-80971 A JP 2009-135103 A

  The description in Patent Document 1 and Patent Document 2 disclosed a limited method of using polyacrylic acid.

  However, polyacrylic acid, polymethacrylic acid and their derivatives are obtained at a low cost, and expanding their applicability is very beneficial for industrial development. Further, polyacrylic acid or the like is superior to other binders in that it can suppress side reactions at the electrode of the lithium ion secondary battery.

  The present invention has been made in view of such circumstances. Polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid (hereinafter, these polymers are collectively referred to as “poly (meth) acrylic acid”). It is an object of the present invention to provide a new method for producing an electrode using the above.

  The present inventor has intensively studied the possibility of using poly (meth) acrylic acid through trial and error. Here, the inventor unexpectedly recalled that the electrode body previously supported by another binder was coated with poly (meth) acrylic acid. And this inventor repeated many experiment and came to complete this invention.

The method for producing an electrode for a non-aqueous secondary battery of the present invention is as follows.
a) preparing an electrode body comprising a current collector, an active material and a binder;
b) preparing a polyacrylic acid, polymethacrylic acid, or a copolymer solution of acrylic acid and methacrylic acid,
c) contacting the electrode body with the solution;
It is characterized by including.

  A new method for producing an electrode using poly (meth) acrylic acid can be provided. The electrode for a non-aqueous secondary battery of the present invention has a structure supported by another binder in advance. Therefore, the electrode for nonaqueous secondary batteries of the present invention has binding electrochemical stability while supplementing the low resin strength of poly (meth) acrylic acid.

It is a cross-sectional schematic diagram which shows the one aspect | mode of the electrode for non-aqueous secondary batteries of this invention.

  Below, the form for implementing this invention is demonstrated. Unless otherwise specified, the numerical range “ab” described herein includes the lower limit “a” and the upper limit “b”. The numerical range can be configured by arbitrarily combining these upper limit value and lower limit value and the numerical values listed in the examples. Furthermore, numerical values arbitrarily selected from the numerical value range can be used as upper and lower numerical values.

The method for producing an electrode for a non-aqueous secondary battery of the present invention (hereinafter sometimes referred to as “the electrode of the present invention”)
a) preparing an electrode body comprising a current collector, an active material and a binder;
b) preparing a polyacrylic acid, polymethacrylic acid, or a copolymer solution of acrylic acid and methacrylic acid,
c) contacting the electrode body with the solution;
It is characterized by including. And the non-aqueous secondary battery of this invention comprises the electrode of this invention, It is characterized by the above-mentioned.

  A non-aqueous secondary battery refers to a secondary battery using a non-aqueous solvent as a solvent for an electrolytic solution. As a typical non-aqueous secondary battery, a lithium ion secondary battery can be given. The electrode of the present invention may be a negative electrode or a positive electrode.

Hereinafter, the present invention will be described along the method for producing an electrode for a non-aqueous secondary battery of the present invention.
First, a) a step of preparing an electrode body having a current collector, an active material, and a binder will be described.
The electrode body includes a current collector and an active material layer including an active material and a binder.
The current collector is a chemically inert electronic high conductor for keeping current flowing through the electrode during discharge or charging of the secondary battery. As the current collector, at least one selected from silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, chromium, molybdenum, and stainless steel Examples of such a metal material can be given. The current collector may be covered with a known protective layer.

  The current collector can take the form of a foil, a sheet, a film, a linear shape, a rod shape, a mesh shape, or the like. Therefore, metal foils, such as copper foil, nickel foil, aluminum foil, stainless steel foil, can be used suitably as a collector. When the current collector is in the form of foil, sheet or film, the thickness is preferably in the range of 10 μm to 100 μm.

  Examples of the active material include a negative electrode active material used for a negative electrode and a positive electrode active material used for a positive electrode.

  Examples of the negative electrode active material include a lithium alloy, a carbon-based material capable of inserting and extracting lithium, an element that can be alloyed with lithium, a compound having an element that can be alloyed with lithium, or a polymer material. .

  Examples of the carbon-based material include non-graphitizable carbon, natural graphite, artificial graphite, cokes, graphites, glassy carbons, organic polymer compound fired bodies, carbon fibers, activated carbon, and carbon blacks. Here, the organic polymer compound fired body refers to a material obtained by firing and carbonizing a polymer material such as phenols and furans at an appropriate temperature.

  Specifically, elements that can be alloyed with lithium include Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, Si. , Ge, Sn, Pb, Sb, Bi can be exemplified, and Si or Sn is particularly preferable.

Specific examples of compounds having elements that can be alloyed with lithium include ZnLiAl, AlSb, SiB ₄ , SiB ₆ , Mg ₂ Si, Mg ₂ Sn, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , _{CaSi 2, CrSi 2, Cu 5} Si, FeSi 2, MnSi 2, NbSi 2, TaSi 2, VSi 2, WSi 2, ZnSi 2, SiC, Si 3 N 4, Si 2 N 2 O, SiO v (0 <v ≦ 2), SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSiO 2, LiSnO, TiO _y , ZrO _y , VO _y , CrO _y , MnO _y , FeO _y , CoO _y , NiO _y , CuO _y , ZnO _{y , LiTi z O y, LiV z} O y (0 <y ≦ 3,0 <Z ≦ 1) transition metal oxides, such _as, Li 3 _N, Li o _0.4 N can be exemplified such as lithium nitride compounds such as _0.6, in _{particular, SiO x (0.3 ≦ x ≦} 1.6) is preferable. Moreover, tin compounds, such as a tin alloy (Cu-Sn alloy, Co-Sn alloy, etc.), can be illustrated as a compound which has an element which can be alloyed with lithium. The above-mentioned material may be heated with a carbon source and used as a carbon coat or composite.

  Specific examples of the polymer material include polyacetylene, polypyrrole, terephthalic acid and derivatives thereof.

As the negative electrode active material, a Si material obtained by heating a layered polysilane obtained by treating CaSi ₂ with an acid such as hydrochloric acid or hydrofluoric acid at 300 to 1000 ° C. may be employed. Further, a material obtained by heating the Si material together with a carbon source to form a carbon coat or composite may be employed as the negative electrode active material.

  As the negative electrode active material, one or more of the above can be used. In order to take advantage of the electrode of the present invention, it is preferable to employ a high-capacity Si-containing material as a negative electrode active material that has a large degree of expansion and contraction during charge and discharge.

As the positive electrode active material, the layered compound Li _a Ni _b Co _c Mn _{d De} O _f (0.2 ≦ a ≦ 1.2, b + c + d + e = 1, 0 ≦ e <1, D is Li, Fe, Cr, At least one element selected from Cu, Zn, Ca, Mg, S, Si, Na, K, Al, Zr, Ti, P, Ga, Ge, V, Mo, Nb, W, La, 1.7 ≦ f ≦ 2.1) and Li ₂ MnO ₃ . Further, as a positive electrode active material, a solid solution composed of a spinel such as LiMn ₂ O ₄ and Li ₂ Mn ₂ O ₄ and a mixture of a spinel and a layered compound, LiMPO ₄ , LiMVO _4, or Li ₂ MSiO ₄ (M in the formula) Are selected from at least one of Co, Ni, Mn, and Fe). Furthermore, as the positive electrode active material, tavorite compound (the M a transition metal) LiMPO ₄ F, such as LiFePO ₄ F represented by, Limbo ₃ such LiFeBO ₃ (M is a transition metal) include borate-based compound represented by be able to. Any metal oxide used as the positive electrode active material may have the above composition formula as a basic composition, and a metal element contained in the basic composition may be substituted with another metal element. Further, as the positive electrode active material, a positive electrode active material that does not contain lithium ions contributing to charge / discharge, for example, sulfur alone (S), a compound in which sulfur and carbon are combined, a metal sulfide such as TiS ₂ , V ₂ O, etc. ₅ , oxides such as MnO ₂ , polyaniline and anthraquinone, compounds containing these aromatics in the chemical structure, conjugated materials such as conjugated diacetic acid organic materials, and other known materials can also be used. Further, a compound having a stable radical such as nitroxide, nitronyl nitroxide, galvinoxyl, phenoxyl, etc. may be adopted as the positive electrode active material. When using a positive electrode active material that does not contain lithium, it is necessary to add ions to the positive electrode and / or the negative electrode in advance by a known method. Here, in order to add the ion, a metal or a compound containing the ion may be used.

  The active material layer includes an active material, a binder, and, if necessary, a conductive aid.

  The binder plays a role of securing an active material or a conductive auxiliary agent to the surface of the current collector and maintaining a conductive network in the electrode. As binders, fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluororubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamideimide, alkoxysilyl group-containing resins, styrene- Examples thereof include butadiene rubber (SBR) and carboxymethyl cellulose. These binders may be used singly or in plural.

  The binder is scheduled to come into contact with the poly (meth) acrylic acid solution in the subsequent step c). Here, considering that the poly (meth) acrylic acid solution contains a polar solvent such as water, the above-mentioned binder has a property that is difficult to dissolve in step c), that is, a property that is difficult to dissolve in water. Can be said to be preferable. Examples of such a preferable binder include polyamide-imide, polyimide, styrene-butadiene rubber, or fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluorine rubber. Here, the polyamideimide can be cured by contact with an acid. Considering that the binder comes into contact with the poly (meth) acrylic acid solution in the subsequent step c), curing of the electrode body surface can be expected when polyamideimide is selected as the binder. Therefore, polyamideimide is particularly preferable as the binder.

  Here, polyamideimide, which is a particularly preferable binder, will be described in detail. Polyamideimide means a compound having two or more amide bonds and imide bonds in the molecule.

  Polyamideimide is produced by reacting an acid component that becomes a carbonyl moiety in an amide bond and an imide bond with a diamine component or diisocyanate component that becomes a nitrogen moiety in the amide bond and imide bond. In order to obtain a polyamideimide, it may be produced by the method, or a commercially available polyamideimide may be purchased.

  Acid components used for the production of polyamideimide include trimellitic acid, pyromellitic acid, biphenyltetracarboxylic acid, diphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, diphenylethertetracarboxylic acid, oxalic acid, adipic acid, malonic acid, Sebacic acid, azelaic acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene), cyclohexane-1,4-dicarboxylic acid, cyclohexane-1,3-dicarboxylic acid, Dicyclohexylmethane-4,4′-dicarboxylic acid, terephthalic acid, isophthalic acid, bis (carboxylphenyl) sulfone, bis (carboxylphenyl) ether, naphthalenedicarboxylic acid, Beauty, mention may be made of these anhydrides, acid halides, and derivatives. As the acid component, one or more of the above compounds may be employed. However, from the viewpoint of forming an imide bond, an acid component having a carboxyl group adjacent to the benzene ring is essential. As the acid component, trimellitic anhydride is preferable from the viewpoints of reactivity and heat resistance. In addition to trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, biphenyl as part of the acid component in addition to trimellitic anhydride from the viewpoint of tensile strength, tensile modulus, and electrolyte resistance of polyamideimide It is preferable to employ a tetracarboxylic acid anhydride.

  Examples of the diamine component used for the production of polyamideimide include alkylene diamines such as ethylene diamine, propylene diamine and hexamethylene diamine, 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, isophorone diamine, and bis (4-aminocyclohexyl) methane. Saturated carbocyclic diamine such as m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, bis (4-aminophenyl) sulfone, benzidine, o-tolidine, 2 , 4-tolylenediamine, 2,6-tolylenediamine, xylylenediamine, naphthalenediamine and the like. From the viewpoint of heat resistance and solubility, 4,4'-diaminodiphenylmethane, 2,4-tolylenediamine, o-tolidine, naphthalenediamine, and isophoronediamine are preferable. From the viewpoint of tensile strength and tensile modulus of polyamideimide, o-tolidine and naphthalenediamine are preferable.

  Examples of the diisocyanate component used for producing the polyamideimide include those obtained by replacing the amine of the diamine component with an isocyanate.

  The molecular weight of the polyamideimide is preferably 500 to 100,000, more preferably 1,000 to 50,000, and even more preferably 5,000 to 30,000 in terms of number average molecular weight or weight average molecular weight.

  The blending ratio of the binder in the active material layer is preferably a mass ratio of active material: binder = 1: 0.001 to 1: 0.3, and 1: 0.005 to 1: 0. .2 is more preferable, and 1: 0.01 to 1: 0.15 is still more preferable. This is because when the amount of the binder is too small, the moldability of the electrode is lowered, and when the amount of the binder is too large, the energy density of the electrode is lowered.

  The conductive assistant is added to increase the conductivity of the electrode. Therefore, the conductive auxiliary agent may be added arbitrarily when the electrode conductivity is insufficient, and may not be added when the electrode conductivity is sufficiently excellent. The conductive auxiliary agent may be any chemically inert electronic high conductor, such as carbon black, graphite, acetylene black, ketjen black (registered trademark), vapor grown carbon fiber (Vapor Grown Carbon). Fiber: VGCF) and various metal particles are exemplified. These conductive assistants can be added to the active material layer alone or in combination of two or more. The blending ratio of the conductive additive in the active material layer is preferably a mass ratio of active material: conductive additive = 1: 0.005 to 1: 0.5, and 1: 0.01 to 1: 0. .2 is more preferable, and 1: 0.03 to 1: 0.1 is even more preferable. This is because if the amount of the conductive auxiliary is too small, an efficient conductive path cannot be formed, and if the amount of the conductive auxiliary is too large, the moldability of the active material layer is deteriorated and the energy density of the electrode is lowered.

  The active material layer is formed on the surface of the current collector. In order to obtain an electrode body by forming an active material layer on the surface of the current collector, conventionally known methods such as a roll coating method, a die coating method, a dip coating method, a doctor blade method, a spray coating method, and a curtain coating method are used. The active material may be applied to the surface of the current collector. Specifically, an active material layer-forming composition containing an active material, a binder, and, if necessary, a conductive aid is prepared, and an appropriate solvent is added to the composition to form a slurry, and then current collection is performed. After applying to the surface of the body, it is dried to obtain an electrode body. Examples of the solvent include N-methyl-2-pyrrolidone, methanol, methyl isobutyl ketone, and water. In order to increase the electrode density, the dried body may be compressed to form an electrode body, or may be heated and dried at about 100 to 250 ° C. to form an electrode body.

  As described above, an electrode body including a current collector, an active material, and a binder can be prepared.

  Next, a step of preparing b) polyacrylic acid, polymethacrylic acid, or a copolymer solution of acrylic acid and methacrylic acid (hereinafter sometimes referred to as “poly (meth) acrylic acid solution”) will be described.

  In order to obtain polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid, a commercially available polymer may be purchased, or each monomer may be polymerized under appropriate conditions to obtain a desired molecular weight. The polymer may be obtained.

  The molecular weight of poly (meth) acrylic acid is preferably 1,000 to 3,000,000, more preferably 10,000 to 2,000,000, and even more preferably 100,000 to 1,000,000 in terms of number average molecular weight or weight average molecular weight.

  Examples of the solvent for the poly (meth) acrylic acid solution include water, methanol, ethanol, propanol, and tetrahydrofuran. These solvents may be used alone or in combination.

  Although there is no limitation in particular in the poly (meth) acrylic acid concentration of a poly (meth) acrylic acid solution, the inside of the range of 0.01 mass%-10 mass% is preferable, and the inside of the range of 0.05 mass%-5 mass% is preferable. More preferably, it is more preferably in the range of 0.1% by mass to 3% by mass, and particularly preferably in the range of 0.2% by mass to 2% by mass.

  In order to prepare a poly (meth) acrylic acid solution, the above poly (meth) acrylic acid and a solvent may be mixed, or a commercially available poly (meth) acrylic acid solution may be purchased.

  Next, the step of c) bringing the electrode body into contact with the poly (meth) acrylic acid solution will be described.

  In order to bring the electrode body into contact with the poly (meth) acrylic acid solution, for example, a method of immersing the electrode body in the poly (meth) acrylic acid solution, a method of applying the poly (meth) acrylic acid solution to the electrode body, poly (meth) ) A method of applying an acrylic acid solution to the electrode body in a spray state can be mentioned. From the viewpoint of ease of work, a method of immersing the electrode body in a poly (meth) acrylic acid solution is preferable. In this method, the poly (meth) acrylic acid solution may be stirred, or may be carried out under normal pressure, under pressure or under reduced pressure, or under normal temperature and under heating conditions. In particular, when the method of immersing the electrode body in a poly (meth) acrylic acid solution is adopted as step c), it is preferably carried out under reduced pressure close to a vacuum state. The time for immersing the electrode body in the poly (meth) acrylic acid solution may be appropriately selected depending on the type and concentration of the poly (meth) acrylic acid solution. Examples of the time include 5 seconds to 5 minutes, preferably 10 seconds to 2 minutes.

  When the step c) is completed, it is presumed that the surface of the electrode body is covered with a film made of poly (meth) acrylic acid. Then, as one aspect of the electrode of the present invention, an electrode body including a current collector, an active material, and a binder, and polyacrylic acid, polymethacrylic acid, or acrylic acid formed on the surface of the electrode body It is possible to grasp an electrode for a non-aqueous secondary battery having an acid part having a methacrylic acid copolymer. It is presumed that the acid part acts as a protective film for the electrode body or a hardness increasing agent for the electrode body.

  FIG. 1 is a schematic cross-sectional view showing one embodiment of a nonaqueous secondary battery electrode of the present invention. The current collector 1 is made of an electronic high conductor. An active material layer 2 having an active material and a binder is formed on the surface of the current collector 1. The electrode body 3 includes a current collector 1 and an active material layer 2. An acid part 4 is formed on the surface of the electrode body 3. The electrode 5 includes an electrode body 3 and an acid part 4.

  It is preferable to implement the drying process for removing the solvent of a poly (meth) acrylic acid solution after the said c) process. The drying temperature is less than 200 ° C, preferably 150 ° C or less, and more preferably in the range of 70 to 140 ° C. The drying step is preferably performed under reduced pressure. What is necessary is just to set time enough for the drying time to remove the solvent of a poly (meth) acrylic acid solution suitably. Examples of the drying time include 1 to 4 hours.

  It is preferable that the manufacturing method of the electrode for non-aqueous secondary batteries of this invention includes the following d) process and e) process in addition to the said a) -c) process.

  d) A process for preparing a polyamine solution will be described.

  A polyamine refers to a compound having two or more amino groups in the molecule.

  Polyamines include aliphatic diamines such as ethylenediamine, propylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, 2,5-dimethyl-2,5-hexamethylenediamine, trimethylhexamethylenediamine, and dialkylaminopropylamine. Aliphatic polyamines having 3 or more amino groups in the molecule such as diethylenetriamine, iminobis (propylamine), bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, diaminocyclohexane, isophoronediamine, 4 Saturated carbocyclic polyamines such as 4,4'-methylenebiscyclohexyldiamine, piperazine, N-aminoethylpiperazine, 1,4-bis (2-aminoethyl) pipe Azine, 1,4-bis (2-amino-2-methylpropyl) piperazine, 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5,5] undecane, etc. Heterocyclic polyamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 1,4-phenylenediamine, 4,4′-diaminodiphenylmethane, 2,6-diaminopyridine, m-aminobenzylamine, 2,4 -Tolylenediamine, 2,6-tolylenediamine, diethyltolylenediamine, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 1,3-dimethyl-2,4-diaminobenzene, 1,3- Dimethyl-2,6-diaminobenzene, 1,4-diisopropyl-2,5-diaminobenzene, 2,4-diaminomesitylene, 1-methyl-3, -Diethyl-2,4-diaminobenzene, 2,3-dimethyl-1,4-diaminonaphthalene, 2,6-dimethyl-1,5-diaminonaphthalene, 3,3 ', 5,5'-tetramethylbenzidine, 3,3 ′, 5,5′-tetramethyl-4,4′-diaminodiphenylmethane, 3,5-diethyl-3′-methyl-2 ′, 4-diaminodiphenylmethane, 3,3′-diethyl-2,2 Aromatic polyamines such as '-diaminodiphenylmethane, 4,4'-diamino-3,3'-dimethyldiphenylmethane, benzidine, aminoethylethanolamine, diaminodiphenylsulfone, thiodianiline, 3,3', 5,5'-tetraethyl- 4,4′-diaminobenzophenone, 3,3 ′, 5,5′-tetraethyl-4,4′-diaminodiphenyl ether, 3,3 ′, 5,5′- Hetero atom-containing polyamines such as tiger isopropyl-4,4'-diaminodiphenyl sulfone, polyethylene imine, polyvinyl amine, polyallyl amine, may be mentioned polymeric polyamines such as polyaniline. One or more of the above may be employed as the polyamine.

  The molecular weight of the polymer polyamine is preferably 2 to 2 million in terms of number average molecular weight or weight average molecular weight, more preferably 1000 to 1 million, and further preferably 10,000 to 500,000.

  Examples of the solvent for the polyamine solution include methanol, ethanol, propanol, tetrahydrofuran, N-methyl-2-pyrrolidone, and the like. These solvents may be used alone or in combination.

  In order to prepare a polyamine solution, the above polyamine and solvent may be mixed. The polyamine concentration in the polyamine solution is not particularly limited, but is preferably in the range of 0.01% by mass to 5% by mass, more preferably in the range of 0.02% by mass to 3% by mass, and 0.03% by mass to 2%. The inside of the range of mass% is further more preferable, and the inside of the range of 0.04 mass% to 1 mass% is particularly preferable.

  Next, the step of e) bringing the electrode after step c) into contact with the polyamine solution will be described.

  Examples of the method for bringing the electrode into contact with the polyamine solution include a method of immersing the electrode in the polyamine solution, a method of applying the polyamine solution to the electrode, and a method of applying the polyamine solution to the electrode in a sprayed state. From the viewpoint of ease of work, a method of immersing the electrode in a polyamine solution is preferable. In this method, the polyamine solution may be in a stirred state, or may be carried out under normal pressure, under pressure or under reduced pressure, or under normal temperature and under heating conditions. The time for immersing the electrode in the polyamine solution may be appropriately selected depending on the type and concentration of the polyamine solution. Examples of the time include 5 seconds to 5 minutes, preferably 10 seconds to 2 minutes. When the electrode is brought into contact with the polyamine solution, it is presumed that the carboxylic acid in the acid part including poly (meth) acrylic acid present on the surface of the electrode main body reacts with the amino group of the polyamine to form an ionic bond.

  e) When the step is completed, polyamine is present at least on the surface of the acid portion of the surface of the electrode body. Then, as one embodiment of the electrode of the present invention, an electrode body including a current collector, an active material, and a binder, and polyacrylic acid, polymethacrylic acid, or acrylic acid and methacrylic acid formed on the surface of the electrode body An electrode for a non-aqueous secondary battery having an acid part having an acid copolymer and a polyamine part formed on the surface of the acid part can be grasped. Here, a polyamine part means the location which has a chemical structure derived from a polyamine among the electrodes of this invention.

  On the surface of the electrode of the present invention that has undergone step e), the carboxylic acid of the acid part having poly (meth) acrylic acid formed on the surface of the electrode body and the amino group of the polyamine part are subjected to an acid-base reaction. Ion-bonded. Due to the ionic bond, the poly (meth) acrylic acid molecules on the surface of the electrode body of the present invention can build a strong network with other poly (meth) acrylic acid molecules via polyamines. As a result, it is estimated that the hardness of the surface of the electrode of the present invention is increased. Here, it is known that the active material of the lithium ion secondary battery expands and contracts with the insertion and extraction of lithium. Therefore, it can be said that it is preferable that the active material layer which comprises an electrode and has an active material, and the electrode main body surface applicable to the surface of the said active material layer have the softness | flexibility which can buffer the said expansion and contraction. Then, it can be said that the network having a certain degree of redundancy is preferable. From the viewpoint of providing redundancy in the molecule, the polyamine prepared in step d) is preferably a stretchable polymer polyamine having a saturated hydrocarbon chain such as polyethyleneimine, polyvinylamine, polyallylamine and the like.

  The lithium ion secondary battery as a typical example of the non-aqueous secondary battery of the present invention includes a positive electrode, a negative electrode, a separator, and an electrolytic solution as battery components.

  Although both the positive electrode and the negative electrode may be the electrode of the present invention, either the positive electrode or the negative electrode may be the electrode of the present invention. Any known positive electrode or negative electrode that is not an electrode of the present invention may be employed.

  The separator separates the positive electrode and the negative electrode and allows lithium ions to pass while preventing a short circuit of current due to contact between the two electrodes. As separators, natural resins such as polytetrafluoroethylene, polypropylene, polyethylene, polyimide, polyamide, polyaramid (Aromatic polymer), polyester, polyacrylonitrile and other polysaccharides, cellulose, amylose and other polysaccharides, fibroin, keratin, lignin and suberin Examples thereof include porous bodies, nonwoven fabrics, and woven fabrics using one or more electrically insulating materials such as polymers and ceramics. The separator may have a multilayer structure.

  The electrolytic solution includes a nonaqueous solvent and an electrolyte dissolved in the nonaqueous solvent.

  As the non-aqueous solvent, cyclic esters, chain esters, ethers and the like can be used. Examples of cyclic esters include ethylene carbonate, propylene carbonate, butylene carbonate, gamma butyrolactone, vinylene carbonate, 2-methyl-gamma butyrolactone, acetyl-gamma butyrolactone, and gamma valerolactone. Examples of chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, propionic acid alkyl ester, malonic acid dialkyl ester, and acetic acid alkyl ester. Examples of ethers include tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-diethoxyethane, and 1,2-dibutoxyethane. As the non-aqueous solvent, a compound in which part or all of hydrogen in the chemical structure of the specific solvent is substituted with fluorine may be employed.

Examples of the electrolyte include lithium salts such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , and LiN (CF ₃ SO ₂ ) ₂ .

As an electrolytic solution, 0.5 mol / l to 1.7 mol of a lithium salt such as LiClO ₄ , LiPF ₆ , LiBF ₄ , LiCF ₃ SO _{3 in} a nonaqueous solvent such as ethylene carbonate, dimethyl carbonate, propylene carbonate, and diethyl carbonate. A solution dissolved at a concentration of about 1 / l can be exemplified.

  A method for producing a lithium ion secondary battery as a representative example of the non-aqueous secondary battery of the present invention will be described below.

  A separator is sandwiched between the positive electrode and the negative electrode to form an electrode body. The electrode body may be either a stacked type in which the positive electrode, the separator and the negative electrode are stacked, or a wound type in which the positive electrode, the separator and the negative electrode are sandwiched. After connecting between the positive electrode current collector and the negative electrode current collector to the positive electrode terminal and the negative electrode terminal connected to the outside using a current collecting lead or the like, an electrolytic solution is added to the electrode body to form a lithium ion secondary battery. It is good to do.

  The shape of the nonaqueous secondary battery of the present invention is not particularly limited, and various shapes such as a cylindrical shape, a square shape, a coin shape, and a laminate shape can be employed.

  The non-aqueous secondary battery of the present invention may be mounted on a vehicle. The vehicle may be a vehicle that uses electric energy from a non-aqueous secondary battery for all or a part of its power source. For example, the vehicle may be an electric vehicle, a hybrid vehicle, or the like. When a non-aqueous secondary battery is mounted on a vehicle, a plurality of non-aqueous secondary batteries may be connected in series to form an assembled battery. Examples of devices equipped with non-aqueous secondary batteries include various home appliances driven by batteries such as personal computers and portable communication devices, office devices, and industrial devices in addition to vehicles. Furthermore, the non-aqueous secondary battery of the present invention includes a wind power generation, solar power generation, hydroelectric power generation and other power system power storage device and power smoothing device, power for ships and / or power supply sources for auxiliary equipment, aircraft, Power supply for spacecraft and / or auxiliary equipment, auxiliary power supply for vehicles that do not use electricity as a power source, power supply for mobile home robots, power supply for system backup, power supply for uninterruptible power supply, You may use for the electrical storage apparatus which stores temporarily the electric power required for charge in the charging station for electric vehicles.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. The present invention can be implemented in various forms without departing from the gist of the present invention, with modifications and improvements that can be made by those skilled in the art.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, this invention is not limited to a following example.

(Production Example 1)
Si material used as a negative electrode active material was manufactured as follows.
5 g of CaSi ₂ was added to 20 mL of concentrated hydrochloric acid containing 1% by mass of hydrogen fluoride bathed in an ice bath at 0 ° C. and stirred for 1 hour. Thereafter, water was added and the mixture was further stirred for 5 minutes, and the reaction solution was filtered to obtain a yellow powder. The yellow powder was washed with water and ethanol, and dried under reduced pressure to obtain 5.5 g of layered polysilane. The layered polysilane was heated to 500 ° C. under an argon atmosphere to obtain a Si material from which hydrogen was released from the polysilane. The Si material was heated to 750 ° C. in an argon atmosphere containing 10% by mass of acetylene to obtain a carbon-coated Si material.

(Production Example 2)
A polyamideimide serving as a binder was produced as follows.
Under an inert gas atmosphere, trimellitic anhydride and the same mole of methylene bis-4,1-phenylene bisisocyanate were dissolved in N-methyl-2-pyrrolidone so that the total amount was 15% by mass. Thereafter, the reaction solution was heated to 100 ° C. under an inert gas atmosphere and under stirring conditions, and reacted for 6 hours to obtain a polyamideimide having a weight average molecular weight of 8,000.

Example 1
The electrode of the present invention was manufactured as follows.

a) Process 85 parts by mass of the carbon-coated Si material obtained in Production Example 1 as the negative electrode active material, 5 parts by mass of acetylene black as the conductive additive, and 10 parts of polyamideimide obtained in Production Example 2 as the binder Partial mixing was performed to obtain an active material layer forming composition. N-methyl-2-pyrrolidone was added to the composition to form a slurry.
An electrolytic copper foil having a thickness of 20 μm was prepared as a current collector. The slurry was applied to the surface of the copper foil using a doctor blade so as to form a film. The copper foil coated with the slurry was dried at 80 ° C. for 20 minutes to remove N-methyl-2-pyrrolidone by volatilization. As a result, a copper foil having a negative electrode active material layer formed on the surface was obtained. The copper foil was compressed with a roll press so that the negative electrode active material layer had a thickness of 20 μm to obtain a bonded product. This joined product was dried under reduced pressure at 200 ° C. for 2 hours to obtain an electrode body of Example 1. The density of the negative electrode active material layer in the electrode body of Example 1 was 1.0 g / cm ³ .

b) Process 0.5 mass% polyacrylic acid aqueous solution was prepared. The polyacrylic acid used was Aqualic AS58 (Nippon Shokubai Co., Ltd.), and its weight average molecular weight was 800,000.

c) Process The said electrode main body was immersed in 0.5 mass% polyacrylic acid aqueous solution for 1 minute at normal temperature. The immersed electrode was air-dried for 1 hour and then dried under reduced pressure at 130 ° C. for 3 hours. The electrode thus obtained was used as the electrode of Example 1.

Nonaqueous secondary battery manufacturing process Using the electrode of Example 1, a half cell was manufactured as follows.
The electrode of Example 1 was cut at a diameter of 11 mm to obtain an evaluation electrode. A metal lithium foil was cut to a diameter of 14 mm to obtain a counter electrode. As a separator, a glass filter (Hoechst Celanese) and celgard 2400 (Polypore Corporation), which is a single-layer polypropylene, were prepared. It was also prepared an electrolyte solution obtained by dissolving LiPF ₆ at 1 mol / L in a solvent obtained by mixing 50 parts by volume of ethylene carbonate and diethyl carbonate 50 parts by volume. Two kinds of separators were sandwiched between the counter electrode and the evaluation electrode in the order of the counter electrode, the glass filter, celgard 2400, and the evaluation electrode, thereby forming an electrode body. This electrode body was accommodated in a coin-type battery case CR2032 (Hosen Co., Ltd.), and an electrolyte was further injected to obtain a coin-type battery. This was designated as the lithium ion secondary battery of Example 1.

(Example 2)
The steps a) and b) were performed in the same manner as in Example 1.

c) Process The electrode main body was immersed in 0.5 mass% polyacrylic acid aqueous solution for 1 minute at normal temperature. The immersed electrode was air-dried for 1 hour.

d) Step Polyethyleneimine (Aldrich) having a weight average molecular weight of 200,000 was employed as the polyamine. A polyamine was dissolved in ethanol to prepare a 0.05 mass% polyamine solution.

e) Process The electrode which passed through the process c) was immersed for 1 minute in the 0.05 mass% polyamine solution at normal temperature. The immersed electrode was air-dried for 1 hour and then dried under reduced pressure at 130 ° C. for 3 hours. The electrode thus obtained was used as the electrode of Example 2.

  Thereafter, a lithium ion secondary battery of Example 2 was produced in the same manner as in Example 1.

(Example 3)
A lithium ion secondary battery of Example 3 was manufactured in the same manner as Example 1 except that 85 parts by mass of SiO (Aldrich) was used as the negative electrode active material.

Example 4
A lithium ion secondary battery of Example 4 was manufactured in the same manner as Example 2 except that 85 parts by mass of SiO (Aldrich) was used as the negative electrode active material.

(Comparative Example 1)
The a) process described in Example 1 was performed, and the manufactured electrode body was used as the electrode of Comparative Example 1. Thereafter, the lithium ion secondary battery of Comparative Example 1 was manufactured by the same method as the non-aqueous secondary battery manufacturing process of Example 1 without performing steps b) and c).

(Comparative Example 2)
A lithium ion secondary battery of Comparative Example 2 was produced in the same manner as Comparative Example 1, except that 85 parts by mass of SiO (Aldrich) was employed as the negative electrode active material.

(Evaluation example 1)
About the lithium ion secondary battery of Examples 1-4 and Comparative Examples 1-2, it discharged until the voltage with respect to the counter electrode of an evaluation electrode became 0.01V with DC current 0.2mA, and 10 minutes after discharge was complete | finished Thereafter, charging was performed at a direct current of 0.2 mA until the voltage with respect to the counter electrode of the evaluation electrode became 1.0V. The discharge capacity at this time was defined as the initial discharge capacity, and the charge capacity was defined as the initial charge capacity. The initial efficiency (%) was defined as (initial charge capacity / initial discharge capacity) × 100.

  Moreover, the said discharge and charge are made into 1 cycle, 20 cycles for the lithium ion secondary batteries of Examples 1-2 and Comparative Example 1, and for the lithium ion secondary batteries of Examples 3-4 and Comparative Example 2 In this case, 40 cycles of discharge charging were performed. (Charge capacity after 20 cycles or 40 cycles / initial charge capacity) × 100 was defined as a capacity retention rate (%).

  In Evaluation Example 1, storing Li in the evaluation electrode is referred to as discharging, and discharging Li from the evaluation electrode is referred to as charging.

  The results of the lithium ion secondary batteries of Examples 1 and 2 and Comparative Example 1 are shown in Table 1, and the results of the lithium ion secondary batteries of Examples 3 to 4 and Comparative Example 2 are shown in Table 2, respectively.

  The lithium ion secondary batteries of Examples 1 and 2 had a higher capacity retention rate than the lithium ion secondary battery of Comparative Example 1. Similarly, the capacity retention rate of the lithium ion secondary batteries of Examples 3 and 4 was higher than that of the lithium ion secondary battery of Comparative Example 2. It was confirmed that an excellent electrode was obtained by the step c). In particular, it is worthy to note that advantageous effects were confirmed in the electrode of the present invention using an Si-containing material known to have a large degree of expansion and contraction associated with insertion and extraction of lithium as an active material.

  Moreover, the lithium ion secondary battery of Example 2 which employ | adopted the electrode which passed through the e) process showed the remarkably high capacity maintenance rate compared with the lithium ion secondary battery of Example 1 and Comparative Example 1. Similarly, the lithium ion secondary battery of Example 4 that employs the electrode that has undergone step e) showed a significantly higher capacity retention rate than the lithium ion secondary batteries of Example 3 and Comparative Example 2. e) It was confirmed that a better electrode can be obtained through the step.

Claims (7)

a) preparing an electrode body comprising a current collector, an active material and a binder;
b) preparing a polyacrylic acid, polymethacrylic acid, or a copolymer solution of acrylic acid and methacrylic acid,
c) contacting the electrode body with the solution;
The manufacturing method of the electrode for non-aqueous secondary batteries characterized by including. d) Step of preparing a polyamine solution e) Step of bringing the electrode after step c) into contact with the polyamine solution,
The manufacturing method of the electrode for nonaqueous secondary batteries of Claim 1 containing this.   The method for producing an electrode for a non-aqueous secondary battery according to claim 1, wherein the binder is polyamideimide. An electrode body comprising a current collector, an active material and a binder;
An acid part having polyacrylic acid, polymethacrylic acid, or a copolymer of acrylic acid and methacrylic acid, formed on the surface of the electrode body;
An electrode for a non-aqueous secondary battery, comprising: A polyamine part formed on the surface of the acid part;
The electrode for nonaqueous secondary batteries of Claim 4 which has these.   The electrode for a nonaqueous secondary battery according to claim 4 or 5, wherein the binder is polyamideimide.   A nonaqueous secondary battery comprising the electrode for a nonaqueous secondary battery obtained by the manufacturing method according to claim 1 or the electrode for a nonaqueous secondary battery according to claim 4.

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