JP2018170251A - Method for manufacturing negative electrode for nonaqueous electrolyte secondary battery, method for manufacturing nonaqueous electrolyte secondary battery, and method for manufacturing negative electrode active material for nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a negative electrode for a nonaqueous electrolyte secondary battery, by which the increase in the weight and volume of a negative electrode owing to pre-doping can be suppressed, and a sufficient amount of pre-doping can be performed without lowering a production efficiency in uninterrupted production.SOLUTION: A method for manufacturing a negative electrode for a nonaqueous electrolyte secondary battery comprises the steps of: obtaining a negative electrode mixture layer containing an alloy-based material (A) capable of occluding alkali metals and including silicon or tin, carbon particles (B) and a binder (C) in a predetermined proportion; and bringing the negative electrode mixture layer into contact with a doping solution containing a straight-chain polyphenylene compound (D) and alkali metal ions or alkali-earth metal ions to obtain a pre-doped negative electrode mixture layer containing the alkali metals. The doping solution contains the alkali-metal ions or alkali-earth metal ions at 100 mol% or more and less than 150 mol% to a total of 100 mol% of the straight-chain polyphenylene compound (D).SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a negative electrode for a non-aqueous electrolyte secondary battery, a method for producing a non-aqueous electrolyte secondary battery, and a method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery.

  In recent years, nonaqueous electrolyte secondary batteries such as lithium ion secondary batteries have been widely used as power sources for electronic devices such as mobile phones and digital cameras. The non-aqueous electrolyte secondary battery includes an electrode (a positive electrode and a negative electrode) including a material capable of inserting and extracting an alkali metal or alkaline earth metal such as lithium or sodium (hereinafter, also simply referred to as “alkali metal”), And an electrolyte solution.

  Carbon materials have been mainly used as negative electrode active materials for non-aqueous electrolyte secondary batteries. However, in recent years, it is expected that the discharge capacity of a nonaqueous electrolyte secondary battery can be further increased by using an alloy-based material containing silicon or tin as a negative electrode active material. In a negative electrode active material using an alloy-based material containing silicon or tin, in order to increase charge / discharge efficiency in an initial cycle, a technique for occluding the alkali metals in the negative electrode active material before battery production has been developed ( Hereinafter, the occlusion of alkali metals in the negative electrode active material is also simply referred to as “pre-doping”.

  For example, Patent Document 1 discloses that an electrode (negative electrode) containing SiO is immersed in a solution in which lithium ions and a polycyclic aromatic compound (naphthalene, anthracene, phenanthrene, etc.) are dissolved in a chain monoether, Describes a method of occluding lithium in SiO. According to this method, when the electrode is immersed, the polycyclic aromatic compound acts as a catalyst, and lithium ions are occluded in SiO in the electrode. According to Patent Document 1, in this method, lithium in the electrode can be pre-doped to SiO in the electrode easily and in a short time, and the lithium ion secondary having a large discharge capacity can be obtained by using the electrode as a negative electrode. It is said that a battery will be obtained.

JP 2005-108826 A

  However, according to our study, although the initial charge and discharge efficiency can be increased by pre-doping lithium into the silicon compound contained in the negative electrode by the method described in Patent Document 1, the weight of the negative electrode mixture layer after pre-doping can be improved. It has been found that there is a problem that the increase in the volume and the volume expansion are large and the energy density of the battery is lowered. It is estimated that the increase in weight is due to the polycyclic aromatic compound adhering to the composite material layer. On the other hand, as a factor of volume expansion, it is estimated that the binder used in the composite layer swells with a solution in which lithium ions and polycyclic aromatic compounds are dissolved, so that the volume expansion occurs during pre-doping. Yes.

  On the other hand, the present inventors have prepared an active material-containing layer containing an alloy material (A), carbon particles (B), and a binder (C) at a predetermined ratio, lithium ions and a linear polyphenylene compound. It has been found that a negative electrode mixture layer in which lithium is pre-doped can be obtained by contacting with a dope solution containing (D) while suppressing an increase in mass and volume of the negative electrode mixture layer due to pre-doping.

  On the other hand, in the method using a dope solution containing lithium ions and a linear polyphenylene compound (D), the amount of pre-doped lithium is small compared to the method using a dope solution containing lithium ions and a polycyclic aromatic compound. For this reason, there is a tendency that it is difficult to increase the initial charge / discharge efficiency. In order to increase the initial charge / discharge efficiency, it is desired to increase the amount of pre-dope. For this purpose, the concentration of lithium ions in the dope solution is increased; for example, the dissolution time of lithium metal when preparing the dope solution It is considered effective to lengthen the length. However, if the dissolution time of the lithium metal is lengthened, the preparation time of the dope solution is lengthened, so that the production efficiency during continuous production tends to decrease. Furthermore, it was found that the use of the dope solution thus obtained (dope solution having a high lithium ion concentration) not only does not increase the amount of pre-doped lithium but also may decrease it. .

  The present invention has been made in view of these problems, and is a method for producing a negative electrode for a non-aqueous electrolyte secondary battery that is pre-doped by immersion in a dope solution containing ions of alkali metals and a catalyst. A method for producing a negative electrode for a non-aqueous electrolyte secondary battery, in which the weight and volume of the negative electrode due to pre-doping are suppressed, and a sufficient amount of pre-doping can be performed without lowering the production efficiency during continuous production. An object of the present invention is to provide a method for producing a non-aqueous electrolyte secondary battery using, and a method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery.

[1] A method for producing a negative electrode for a non-aqueous electrolyte secondary battery having a negative electrode mixture layer containing a pre-doped alkali metal or alkaline earth metal, and silicon or tin capable of occluding an alkali metal or alkaline earth metal An alloy material (A) containing carbon particles (B) and a binder (C), the alloy material (A) and carbon particles (B) contained in the anode mixture layer The volume of the alloy material (A) is 10% by volume or more and less than 60% by volume, and the amount of the binder (C) is 100% by mass of the negative electrode mixture layer. The step of obtaining a negative electrode mixture layer that is 4% by mass or more and 13% by mass or less with respect to%, and the negative electrode mixture layer contains a linear polyphenylene compound (D) and alkali metal ions or alkaline earth metal ions. Dope Contacting the solution to obtain a negative electrode mixture layer containing the pre-doped alkali metal or alkaline earth metal, wherein the dope solution has a total number of moles of 100 mol% of the linear polyphenylene compound (D). On the other hand, the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries which contains the said alkali metal ion or alkaline-earth metal ion 100 mol% or more and less than 150 mol%.
[2] In the spectrum obtained by ⁷ Li-NMR measurement of the dope solution at 20 ° C. or higher and 30 ° C. or lower, the main peak existing in the range of 3 ppm or more and 8 ppm or less in chemical shift is peak A, and the chemical shift value is When the minor peak existing in the range of 1 ppm or more and 5 ppm or less is defined as peak B, the difference (A−B) in chemical shift value between peak A and peak B is more than 1.5 and less than 3, [1] The manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries of description.
[3] The method for producing a negative electrode for a nonaqueous electrolyte secondary battery according to [1] or [2], wherein the linear polyphenylene compound (D) is biphenyl, terphenyl, or a derivative thereof.
[4] The dope solution is obtained by adding the alkali metal or the alkaline earth metal to a solvent in which the linear polyphenylene compound (D) is dissolved, and then stirring the mixture for 2 hours or less. [3] The method for producing a negative electrode for a nonaqueous electrolyte secondary battery according to any one of [3].
[5] The method for producing a negative electrode for a nonaqueous electrolyte secondary battery according to [4], wherein the solvent is tetrahydrofuran.
[6] The nonaqueous electrolyte according to any one of [1] to [5], wherein the concentration of the linear polyphenylene compound (D) in the dope solution is 0.1 mol / L or more and 4.0 mol / L or less. A method for producing a negative electrode for a secondary battery.
[7] The non-aqueous material according to any one of [1] to [6], wherein the alloy-based material (A) is a silicon oxide represented by SiO _x (0.5 ≦ x ≦ 1.5). A method for producing a negative electrode for an electrolyte secondary battery.
[8] At least a part of the silicon oxide is coated with a carbon material, and the mass of the carbon material to be coated is 2 mass relative to the total mass of the silicon oxide contained in the negative electrode mixture layer. The manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries as described in [7] which is% -50 mass%.
[9] The nonaqueous electrolyte secondary battery according to any one of [1] to [8], wherein the carbon particles (B) include at least one selected from the group consisting of natural graphite, artificial graphite, and carbon-coated graphite. Manufacturing method for negative electrode.
[10] The negative electrode for a nonaqueous electrolyte secondary battery according to any one of [1] to [9], wherein the binder (C) includes an imide bond-containing polymer (C1) or a carboxylate-containing polymer (C2). Manufacturing method.
[11] including a step of obtaining a negative electrode by the production method according to any one of [1] to [10], and a step of obtaining a nonaqueous electrolyte secondary battery including the negative electrode, the positive electrode, and an electrolytic solution, The non-aqueous electrolyte 2 has a larger total molar amount of alkali metal and alkaline earth metal contained in the negative electrode at full charge than the molar amount of alkali metal and alkaline earth metal calculated from the capacity of the positive electrode active material of the positive electrode. A method for manufacturing a secondary battery.
[12] A method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery containing a pre-doped alkali metal or alkaline earth metal, and an alloy system containing silicon or tin capable of occluding an alkali metal or alkaline earth metal A negative electrode active material made of the material (A) is brought into contact with a dope solution containing a linear polyphenylene compound (D) and an alkali metal ion or an alkaline earth metal ion, and the predoped alkali metal or alkaline earth metal is obtained. Including a step of obtaining a negative electrode active material, wherein the dope solution contains 100 mol% or more of the alkali metal ions or alkaline earth metal ions to 100 mol% of the total number of moles of the linear polyphenylene compound (D). The manufacturing method of the negative electrode active material for nonaqueous electrolyte secondary batteries containing less than mol%.
[13] In the spectrum obtained by ⁷ Li-NMR measurement of the dope solution at 20 ° C. or more and 30 ° C. or less, the main peak existing in the range of 3 ppm or more and 8 ppm or less in chemical shift is peak A, and the chemical shift value is When the minor peak existing in the range of 1 ppm or more and 5 ppm or less is defined as peak B, the difference (A−B) in chemical shift value between peak A and peak B is more than 1.5 and less than 3, [12] The manufacturing method of the negative electrode active material for nonaqueous electrolyte secondary batteries of description.
[14] The method for producing a negative electrode active material for a nonaqueous electrolyte secondary battery according to [12] or [13], wherein the linear polyphenylene compound (D) is biphenyl, terphenyl, or a derivative thereof.
[15] The alloy material containing silicon or tin according to any one of [12] to [14], which is a silicon oxide represented by SiO _x (0.5 ≦ x ≦ 1.5). A method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery.
[16] The method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery according to [15], wherein at least a part of the silicon oxide is coated with a carbon material.

  According to the present invention, a method for producing a negative electrode for a non-aqueous electrolyte secondary battery that is pre-doped by immersion in a dope solution containing ions of alkali metals and a catalyst, the weight and volume of the negative electrode being reduced by pre-doping is suppressed. And the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries which can perform sufficient amount of pre dope, without reducing the production efficiency at the time of continuous production is provided.

  As described above, the inventors of the present invention have used a negative electrode mixture layer containing an alloy-based material (A), carbon particles (B), and a binder (C) in a predetermined ratio as lithium ions. And a dope solution containing a linear polyphenylene compound (D) are obtained to obtain a negative electrode mixture layer in which a sufficient amount of lithium is pre-doped while suppressing an increase in mass and volume of the negative electrode mixture layer due to pre-doping. I found out that

  That is, by combining the alloy material (A) and the carbon particles (B) as the negative electrode active material, compared to the case where the alloy material (A) is contained alone, the alloy material (generated during the first charge / discharge reaction) ( It has been found that the amount of irreversible component derived from A) can be reduced. Further, by using the linear polyphenylene compound (D) as a catalyst at the time of pre-doping, the mass of the negative electrode mixture layer by pre-doping and the case of using a polycyclic aromatic compound as a catalyst at the time of pre-doping as in Patent Document 1 and It has been found that an increase in volume can be suppressed. This is because the linear polyphenylene compound (D) has a smaller interaction with the negative electrode mixture layer, particularly the carbon particles (B), and is less likely to adhere to the negative electrode mixture layer than the polycyclic aromatic compound. It is estimated.

  On the other hand, in the method using the dope solution containing lithium ions and the linear polyphenylene compound (D), the amount of lithium to be pre-doped is compared with the case of using the dope solution containing lithium ions and the polycyclic aromatic compound. Therefore, there was a tendency that it was difficult to improve the initial charge / discharge efficiency.

  In order to increase the amount of pre-doped lithium, the concentration of lithium ions in the dope solution should be increased; for that purpose, the dissolution time of lithium metal (after the addition of lithium metal to the solvent when preparing the dope solution) It is considered effective to lengthen the stirring and reaction time. However, if the dissolution time of the lithium metal is too long, it takes time to prepare the dope solution, so that the production efficiency during continuous production tends to decrease. Furthermore, even if the dope solution thus obtained (dope solution having a high lithium ion concentration) is used, not only can the amount of pre-doped lithium be increased, but also the dissolution time of lithium metal (or in the dope solution). It has been found that the amount of pre-doped lithium rather decreases when the lithium ion concentration of) reaches a certain level.

  The cause of this is not clear, but is presumed as follows. The higher the lithium ion concentration in the dope solution (or the longer the dissolution time of lithium metal), the easier it is to stabilize the bonding state between the lithium ions and the linear polyphenylene compound (D). As a result, it is considered that lithium ions bonded to the linear polyphenylene compound (D) are less likely to react with the alloy material (A) in the negative electrode mixture layer, and the amount of predoped lithium is reduced. In other words, in order to increase the amount of pre-doped lithium, the lithium ion concentration in the dope solution is appropriately increased, but the bonding state between the linear polyphenylene compound (D) and the lithium ions is not stabilized too much. It is desirable. For that purpose, it is desirable to adjust the ion concentration of alkali metals with respect to the linear polyphenylene compound (D) in the dope solution to an appropriate range.

  The present inventors set the ion concentration of alkali metals in the dope solution to 100 mol% or more and less than 150 mol% with respect to 100 mol% of the total number of moles of the linear polyphenylene compound (D), so that the amount of pre-doping Has been found to be effective. Thereby, the amount of pre-doping can be increased without reducing the production efficiency during continuous production. The present invention has been made based on such knowledge.

1. Manufacturing method of negative electrode for non-aqueous electrolyte secondary battery The manufacturing method of the negative electrode for non-aqueous electrolyte secondary battery of the present invention is as follows. 1) Negative electrode containing alloy material (A), carbon particles (B), and binder (C) A step of obtaining a composite layer, and 2) bringing the obtained negative electrode composite layer into contact with a dope solution containing a linear polyphenylene compound (D) and ions of alkali metals, thereby containing predoped alkali metals. And obtaining a negative electrode mixture layer (also referred to as a “pre-doped negative electrode mixture layer”). Moreover, the manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries of this invention may further include the process of removing an impurity from the obtained negative mix layer, etc. as needed. Hereinafter, each process will be described.

1-1. Step of obtaining negative electrode composite layer The negative electrode composite layer is prepared by dispersing an alloy-based material (A), carbon particles (B), a binder (C), and a conductive auxiliary agent (E) as necessary in a solvent. It is obtained as a composite paste, which is applied to a current collector. After application of the negative electrode mixture paste, the negative electrode mixture layer is obtained by drying and solidifying the negative electrode mixture paste by removing the solvent as necessary.

  Current collector material is silicon and / or silicon alloy, tin and its alloys, silicon-copper alloy, copper, nickel, stainless steel, nickel-plated steel, etc., carbon cloth, carbon paper such as carbon paper, etc. It can be.

  Hereinafter, each component contained in the negative electrode mixture paste and the preparation method thereof will be described.

(Alloy material (A))
The alloy-based material (A) is a material containing silicon or tin capable of occluding an alkali metal or alkaline earth metal as a constituent element, and functions as a negative electrode active material (capable of occluding and releasing alkali metals) It is. The alloy material (A) becomes a composite with alkali metals by pre-doping.

  The type of alkali metal that can be occluded by the alloy material (A) is not particularly limited, but lithium, sodium, magnesium, potassium and calcium are preferable, lithium and sodium are more preferable, and lithium is particularly preferable.

  Examples of the alloy-based material (A) containing silicon as a constituent element include (i) silicon fine particles, (ii) magnesium, nickel, titanium, molybdenum, cobalt, calcium, chromium, copper, iron, manganese, niobium, tantalum, An alloy of vanadium, tungsten, or zinc and silicon; (iii) a compound of boron, nitrogen, oxygen or carbon and silicon; and (iv) a metal exemplified in (ii) above and exemplified in (iii) above. And composite materials with silicon compounds.

Specific examples of the alloy-based material (A) containing silicon as a constituent element include Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , and CaSi which are specific examples of (ii) above. _{2, CrSi 2, Cu 5 Si} , FeSi 2, MnSi 2, NbSi 2, TaSi 2, VSi 2, WSi 2, and ZnSi _{2, SiB} 4 is a specific example of the above _{(iii), SiB 6, SiC} , SiO x (0.5 ≦ x ≦ 1.5), Si ₃ N ₄ , and Si ₂ N ₂ O which is a specific example of the above (iv), LiSiO, and the like are included.

  Examples of alloy materials (A) containing tin as a constituent element include (i) silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony or chromium, tin (Ii) a compound of oxygen or carbon and tin, (iii) a composite material of the metal exemplified in (i) above and the tin compound exemplified in (ii) above.

Specific examples of the alloy-based material (A) containing tin as a constituent element include Mg ₂ Sn, which is a specific example of (i) above, and SnO _w (0 <w ≦ 2), which is a specific example of (ii) above. ) And LiSnO, and SnSiO ₃ which is a specific example of the above (iii).

  The alloy-based material (A) may contain only one kind of alloy or compound containing silicon or tin, or may contain two or more kinds. In addition, these surfaces may be coated with a carbon material or the like from the viewpoint of enhancing conductivity.

Examples of particularly preferable alloy-based materials (A) include silicon oxides represented by SiO _x (0.5 ≦ x ≦ 1.5) (hereinafter also simply referred to as “silicon oxides”). In the present invention, SiO _x (0.5 ≦ x ≦ 1.5) is a general term for amorphous silicon oxides obtained from silicon dioxide (SiO ₂ ) and metal silicon (Si) as raw materials. It is a formula. In SiO _x (0.5 ≦ x ≦ 1.5), when x is less than 0.5, the proportion of the Si phase increases, so the volume change during charge / discharge increases, and the nonaqueous electrolyte secondary battery The cycle characteristics may be degraded. Moreover, when x exceeds 1.5, the ratio of Si phase may fall and energy density may fall. A more preferable range of x is 0.7 ≦ x ≦ 1.2.

Particle size D ₅₀ of the alloy-based material (A) is better generally small Preferably, the agglomerate too small, it may be coarse. D ₅₀ refers to a particle diameter corresponding to a volume distribution integrated value of 50% in particle size distribution measurement by laser diffraction, that is, a median diameter measured on a volume basis. From such a viewpoint, the particle size D ₅₀ of the alloy material (A) is preferably 1 μm or more and 40 μm or less, and more preferably 2 μm or more and 30 μm or less.

  Moreover, in order to improve electroconductivity, at least a part of the surface of the silicon oxide may be coated with a carbon material. When the silicon oxide is coated with a carbon material, the adhesion amount of the carbon material in the composite may be 2% by mass or more and 50% by mass or less with respect to the total mass of the silicon oxide. Preferably, it is 3 mass% or more and 40 mass% or less, More preferably, it is 3 mass% or more and 25 mass% or less. When the adhesion amount of the carbon material is 2% by mass or more, the conductivity of the silicon oxide is sufficiently increased, and the current collection efficiency of the secondary battery negative electrode is likely to be increased. On the other hand, if the amount of carbon material attached is excessive, the capacity of the non-aqueous electrolyte secondary battery using the negative electrode for a secondary battery may decrease, but the amount of carbon material attached may be 50% by mass or less. In this case, the capacity is hardly reduced.

The electric conductivity of the silicon oxide coated with the carbon material is preferably 1 × 10 ⁻⁶ S / m or more, and more preferably 1 × 10 ⁻⁴ S / m or more. The electrical conductivity is a value obtained by filling a powder to be measured in a cylindrical cell having four terminals and measuring a voltage drop when a current is passed through the powder to be measured.

(Carbon particles (B))
The carbon particles (B) are particles containing a graphite material and function as a negative electrode active material (a material capable of occlusion and release of alkali metals).

The particle diameter D ₅₀ of the carbon particles (B) is not particularly limited, but is preferably 1 μm or more. D ₅₀ refers to a particle diameter corresponding to a volume distribution integrated value of 50% in particle size distribution measurement by laser diffraction, that is, a median diameter measured on a volume basis. The particle diameter _{D 50} of the carbon particles (B) is preferably from 8.0 times 1.0 times the particle diameter _{D 50} of the alloy-based material (A), 1.5 times or more 6.5 It is more preferable that it is 2 times or less, and it is more preferable that it is 2.0 times or more and less than 6.0 times. The particle size D ₅₀ of the carbon particles (B), in the above-particle diameter D ₅₀ of the alloy-based material (A) and on the same diameter or less, to reduce the volume change of the negative electrode mixture layer due to charge and discharge cycles, It is possible to make it difficult for the negative electrode composite material layer to peel off. On the other hand, when the ratio is 8.0 times or less, the specific surface area of the carbon particles (B) is not excessively increased, and the capacity is not easily reduced due to the electrolytic solution decomposing the carbon particles (B).

  Specific examples of the carbon particles (B) include natural graphite, artificial graphite, non-graphitizable carbon (hard carbon), graphitizable carbon (soft carbon), mesocarbon microbeads, graphite particles and the surface thereof. Particles composed of a carbonaceous layer (that is, carbon-coated graphite), particles obtained by attaching carbon fibers to graphite particles, and the like are included. Of these, the carbon particles (B) are preferably at least one of natural graphite, artificial graphite, and carbon-coated graphite. By using these carbon particles, the lithium ion is suppressed from being doped into the carbon particles (B) during pre-doping, and the lithium ion is pre-doped into the silicon compound more selectively, improving the initial charge / discharge efficiency. Cheap. The carbon particles (B) may have any shape such as a spherical shape, a substantially spherical shape, and a flat shape, but in the present invention, particles having an aspect ratio of less than 10 are referred to as carbon particles (B).

  From the viewpoint of making it difficult to lower the charge / discharge efficiency of the negative electrode after pre-doping with an alkali metal (for example, charge / discharge efficiency after being left in dry air for 24 hours), the carbon particles (B) are natural graphite, artificial graphite. And carbon-coated graphite.

Wherein the carbon particles (B), the total pore volume measured by nitrogen gas adsorption method, be 1.0 × ¹⁰ -2 ^cm 3 / g or more 1.0 × ¹⁰ -1 ^cm 3 / g or less The average pore diameter is preferably 20 nm or more and 50 nm or less. The total pore volume and the average pore diameter are more preferably 1.5 × 10 ⁻² cm ³ / g or more and 9.0 × 10 ⁻² cm ³ / g or less and 25 nm or more and 40 nm or less, respectively. More preferably, it is 0 × 10 ⁻² cm ³ / g or more and 7.0 × 10 ⁻² cm ³ / g or less and 25 nm or more and 35 nm or less. When the total pore volume and the average pore diameter of the carbon particles (B) satisfy the above ranges, the electrolytic solution easily penetrates into the active material. Therefore, since the negative electrode for secondary batteries containing the carbon particles (B) has high ionic conductivity and low electrode resistance, the charge / discharge capacity and load characteristics of the nonaqueous electrolyte secondary battery can be improved. Furthermore, if the total pore volume and the average pore diameter of the carbon particles (B) satisfy the above ranges, the carbon particles (B) are elastically deformed even if the alloy-based material (A) expands during charging. The deformation of the composite material layer is suppressed. As a result, the negative electrode mixture layer is difficult to peel from the current collector, and good cycle characteristics are easily maintained. The carbon particles (B) are preferably particles in which at least one of the particle diameter D ₅₀ and the total pore volume satisfies the above-described range.

  More preferably, the carbon particles (B) are secondary aggregates formed by aggregating or bonding the primary particles containing the graphite material. At this time, the primary particles of the carbon particles (B) are desirably flat. In the carbon particles (B) having such a shape, good conductivity is easily maintained even after the charge / discharge cycle, and an increase in electrode resistance is easily suppressed. As a result, the cycle life of the nonaqueous electrolyte secondary battery can be extended. Examples of the carbon particles (B) made of flat primary particles include MAG and the like.

(Binder (C))
The binder (C) is a polymer that functions as a binder. The binder (C) preferably contains an imide bond-containing polymer (C1) or a carboxylate-containing polymer (C2). Since these polymers easily move lithium ions, not only the amount of pre-doping is easily increased, but also the swelling resistance to the dope solution is high, so that the volume expansion of the negative electrode mixture layer during pre-doping can be easily suppressed.

<Imide bond-containing polymer (C1)>
The imide bond-containing polymer (C1) is not particularly limited as long as it is a polymer containing an imide bond in the molecule. Examples of the imide bond-containing polymer include polyimide and polyamideimide. The imide bond-containing polymer (C1) preferably includes a repeating structural unit having an amic acid structure or an imide bond obtained by reacting a diamine compound and tetracarboxylic dianhydride. In the imide bond-containing polymer (C1), only one type of the repeating structural unit may be included, or two or more types may be included. That is, the imide bond-containing polymer (C1) may be a homopolymer or a copolymer.

  In the imide bond-containing polymer (C1) containing the repeating structural unit, the molecular weight of the repeating structural unit is preferably 600 or less, and more preferably 500 or less. In addition, when two or more types of repeating structural units are contained in the imide bond-containing polymer (C1), the average molecular weight of these repeating structural units is preferably 600 or less. When the molecular weight of the repeating structural unit is 600 or less, the imide bond-containing polymer (C1) is less likely to swell when lithium is pre-doped into the negative electrode mixture layer, and peeling of the negative electrode mixture layer from the current collector is suppressed. Is done.

  Moreover, the diamine compound for constituting the repeating structural unit preferably contains 50 mol% or more, preferably 70 mol% or more of a low molecular weight diamine compound having a molecular weight of 300 or less with respect to the total amount of the diamine compound. More preferred. When the diamine compound is a low molecular weight diamine compound, the molecular weight of the above repeating structural unit tends to be small.

The imide bond-containing polymer (C1) is preferably a polyimide having a structural unit represented by the following general formula (1). The polyimide containing the structural unit represented by the general formula (1) contains a relatively large number of aromatic rings in the molecule and has a rigid molecular structure, and thus has a high elastic modulus and a low thermal expansion coefficient. Therefore, when the negative electrode composite material layer is pre-doped with lithium, the negative electrode composite material layer hardly changes in volume, and the negative electrode composite material layer becomes difficult to peel from the current collector.

In the general formula (1), m is an integer of 1 or more. A in the general formula (1) is selected from a divalent group represented by the following formula or a divalent aliphatic diamine.

In the above formula, X _{1 to} X ₆ are each a single bond, —O—, —S—, —CO—, —COO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, — SO ₂ — or —NHCO—. When a plurality of groups represented by the above formula are contained in one molecule, X _{1 to} X ₆ may be the same as or different from each other.

A in the general formula (1) may be a divalent group derived from a diamine compound. Examples of diamine compounds include m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3 ′. -Diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4-Aminophenyl) propane, 2,2-bi (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoro Propane, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide, 1,3-bis (3-aminophenyl) benzene, 1,3-bis (4- Aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, 1,4-bis (4-aminophenyl) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis ( 4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenyl) Nyl sulfide) benzene, 1,3-bis (4-aminophenyl sulfide) benzene, 1,4-bis (4-aminophenyl sulfide) benzene, 1,3-bis (3-aminophenylsulfone) benzene, 1,3 -Bis (4-aminophenylsulfone) benzene, 1,4-bis (4-aminophenylsulfone) benzene, 1,3-bis (3-aminobenzyl) benzene, 1,3-bis (4-aminobenzyl) benzene 1,4-bis (4-aminobenzyl) benzene, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 3,3′-bis (3-aminophenoxy) biphenyl, 3,3′- Bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) Biphenyl, bis [3- (3-aminophenoxy) phenyl] ether, bis [3- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4 -Aminophenoxy) phenyl] ether, bis [3- (3-aminophenoxy) phenyl] ketone, bis [3- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] ketone, Bis [4- (4-aminophenoxy) phenyl] ketone, bis [3- (3-aminophenoxy) phenyl] sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-amino Phenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis 3- (3-aminophenoxy) phenyl] sulfone, bis [3- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) Phenyl] sulfone, bis [3- (3-aminophenoxy) phenyl] methane, bis [3- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 2,2-bis [3- (3-aminophenoxy) phenyl] propane, 2,2-bis [3- (4-aminophenoxy) phenyl] propane, 2,2- Bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (4-aminophenoxy) phenyl]- 1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2, , 2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 9,9-bis (4-aminophenyl) fluorene, 9,9-bis (2-methyl-4-aminophenyl) fluorene, 9,9-bis (3-methyl-4-aminophenyl) fluorene, 9,9-bis (2-ethyl-4-aminophenyl) fluorene, 9,9- Bis (3-ethyl-4-aminophenyl) fluorene, 9,9 -Bis (4-aminophenyl) -1-methylfluorene, 9,9-bis (4-aminophenyl) -2-methylfluorene, 9,9-bis (4-aminophenyl) -3-methylfluorene and 9, Aromatic diamines such as 9-bis (4-aminophenyl) -4-methylfluorene, 4,4'-diaminobenzanilide;
1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,3-bis (4-aminobutyl) tetramethyldisiloxane, α, ω-bis (3-aminopropyl) polydimethylsiloxane, α, ω -Bis (3-aminobutyl) polydimethylsiloxane, bis (aminomethyl) ether, 1,2-bis (aminomethoxy) ethane, bis [(2-aminomethoxy) ethyl] ether, 1,2-bis [(2 -Aminomethoxy) ethoxy] ethane, bis (2-aminoethyl) ether, 1,2-bis (2-aminoethoxy) ethane, bis [2- (2-aminoethoxy) ethyl] ether, bis [2- (2 -Aminoethoxy) ethoxy] ethane, bis (3-aminopropyl) ether, ethylene glycol bis (3-aminopropyl) ether, diethylene glycol bis (3-aminopropyl) E) ether, triethylene glycol bis (3-aminopropyl) ether, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7- Diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane 1,4-diaminocyclohexane, 1,4-diaminomethylcyclohexane, 1,3-diaminomethylcyclohexane, 1,2-diaminomethylcyclohexane, 1,2-di (2-aminoethyl) cyclohexane, 1,3-di (2-aminoethyl) cyclohexane, 1,4-di (2-aminoethyl) cyclohexane, bis (4-aminocyclohexane) Aliphatic diamines such as xyl) methane, 2,6-bis (aminomethyl) bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl) bicyclo [2.2.1] heptane;
Etc. are included. These derived structures may be contained alone or in combination of two or more in the polyimide.

B in the general formula (1) is selected from tetravalent groups represented by the following formula.

Y _{1 to} Y ₆ in the above formula are each a single bond, —O—, —S—, —CO—, —COO—, —C (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, —SO. _2- or -NHCO-. When a plurality of groups represented by B are contained in one molecule, these may be the same as or different from each other.

  B in the general formula (1) may be a tetravalent group derived from an aromatic tetracarboxylic dianhydride. Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, merophanic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′ , 4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, bis ( 3,4-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfide dianhydride, bis (3,4-di Carboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (3 4 Dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis (3,4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3 , 4-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (3,4-dicarboxyphenoxy) biphenyl dianhydride, 2,2-bis [(3,4-dicarboxyphenoxy) phenyl] propane Anhydrides and the like are included. Among these, pyromellitic dianhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are preferable, and 3,3 ′, 4,4′-biphenyltetracarboxylic is particularly preferable. Acid dianhydride. These derived structures may be contained alone or in combination of two or more in the polyimide.

  In addition, the polyimide may partially include a tetravalent group derived from other tetracarboxylic dianhydrides. Examples of other tetracarboxylic dianhydrides include ethylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, 1,1-bis (2,3-dicarboxyl Phenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,2-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3, 6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride and the like are included. In addition, some or all of the hydrogen atoms on the aromatic ring of other tetracarboxylic dianhydrides may be substituted with a fluoro group or a trifluoromethyl group. The structure derived from these may be contained in the polyimide individually by 1 type, and may be contained 2 or more types.

<Carboxylate-containing polymer (C2)>
The carboxylate-containing polymer (C2) may be any polymer in which a salt having a carboxyl group-containing polymer and a metal ion or ammonium ion is formed.

  The degree of neutralization of the carboxylate-containing polymer (C2) that forms the salt is 50% or more. When the degree of neutralization is 50% or more, the capture of lithium ions by the carboxylate-containing polymer (C2) can be suppressed, so that the initial charge / discharge efficiency can be sufficiently increased. Further, when the neutralization degree of the carboxylate-containing polymer (C2) is 50% or more, the swelling resistance to a solution in which alkali metals and linear polyphenylene compound (D) are dissolved is improved. An increase in the volume of the composite material layer can be further suppressed. On the other hand, if the degree of neutralization is too high, the affinity between the active material and the carboxylate-containing polymer (C2) decreases, so that the initial charge / discharge efficiency is not sufficiently increased. The increase in volume may not be sufficiently suppressed. Therefore, the neutralization degree of the carboxylate-containing polymer (C2) is less than 97% from the viewpoint of further improving the initial charge / discharge efficiency and further suppressing the increase in the volume of the negative electrode mixture layer due to pre-doping. Is preferable, and it is more preferable that it is less than 95%.

  Examples of the polymer having a carboxyl group include carboxymethyl cellulose (CMC), polyacrylic acid (PAA), and aqueous emulsions such as acrylic emulsion and olefin emulsion. The polymer having a carboxyl group may be a homopolymer composed of the same repeating unit or a copolymer having a plurality of repeating units.

  Further, the carboxylate-containing polymer (C2) may contain a structure represented by the following formula (2) in an amount of 50 mol% or more when the total number of moles of repeating units of the polymer is 100 mol%. preferable. When the structure represented by the following formula is contained in an amount of 50 mol% or more, the swelling resistance to the electrolytic solution is increased, and the increase in the volume of the negative electrode mixture layer due to pre-doping can be further suppressed. The ratio of the structure represented by the following formula is more preferably 50 mol% or more and less than 100 mol%, and further preferably 70 mol% or more and less than 98 mol%.

In formula (2), M ⁺ is at least one cation selected from Li ⁺ , Na ⁺ , K ⁺ and NH ₄ ⁺ . M ⁺ is preferably Li ⁺ , Na ⁺ and K ^+, more preferably Li ⁺ and Na ⁺ . The carboxylate-containing polymer (C2) may contain a plurality of types of structures represented by the above formula (2) with different M ⁺ .

  The structure of the carboxylate-containing polymer (C2) can be confirmed by electrochemical analysis, nuclear magnetic resonance, ICP mass spectrometry, infrared absorption spectroscopy, Raman spectroscopy, and the like.

  Examples of particularly preferred carboxylate-containing polymer (C2) include lithium salt of polyacrylic acid and sodium salt of polyacrylic acid. By using these carboxylate-containing polymers (C2), the effect of improving the initial charge / discharge efficiency due to the improvement in ionic conductivity in the negative electrode mixture layer and the dissolution of alkali metals and linear polyphenylene compounds (D) It is preferable because the volume expansion reduction effect at the time of pre-doping due to the improvement of the swelling resistance to the prepared solution is easily exhibited.

  The amount of lithium ion or sodium ion contained in the carboxylate-containing polymer (C2) can be measured by ion chromatography or the like.

  Among these, it is preferable that the binder (C) includes the carboxylate-containing polymer (C2) from the viewpoint of easily increasing the amount of pre-dope and having high swelling resistance to the dope solution.

The weight average molecular weight of the binder (C) is preferably 5.0 × 10 ³ or more and 5.0 × 10 ⁵ or less. When the weight average molecular weight is less than 5.0 × 10 ³ , the mechanical strength of the negative electrode mixture layer may be lowered. On the other hand, when the weight average molecular weight exceeds 5.0 × 10 ⁵ , formation of the negative electrode mixture layer tends to be difficult. The weight average molecular weight of the binder (C) can be measured by gel permeation chromatography (GPC).

  The binder (C) may further contain a polymer or synthetic rubber other than the imide bond-containing polymer (C1) and the carboxylate-containing polymer (C2). Examples of such polymers include polyamides such as polyvinylidene fluoride (PVDF), polyimide (PI), polyamideimide (PAI), and aramid. Examples of the synthetic rubber include styrene butadiene rubber (SBR), fluorine rubber (FR), ethylene propylene diene (EPDM), and the like.

(Conductive aid (E))
The negative electrode mixture layer may further contain a conductive additive (E). Such a conductive auxiliary agent (E) is not particularly limited as long as it does not cause a chemical change in the nonaqueous electrolyte secondary battery. For example, carbon fiber or carbon black having an aspect ratio of 10 or more (thermal Black, furnace black, channel black, ketjen black, acetylene black, etc.), metal powder (powder of copper, nickel, aluminum, silver, etc.), metal fibers, polyphenylene derivatives, and the like can be used.

  It is preferable that a conductive support agent (E) contains the carbon fiber whose aspect ratio is 10-1000. The aspect ratio of the carbon fiber is more preferably 10 or more and 500 or less. When such a carbon fiber is combined with the aforementioned carbon particles (B), the capacity and cycle life are likely to increase when the negative electrode is used in a non-aqueous electrolyte secondary battery.

  The amount of each component in the negative electrode mixture paste can be adjusted so that the content of each component in the obtained negative electrode mixture layer falls within the range described below.

(solvent)
The solvent that can be used for the negative electrode mixture paste is not particularly limited as long as it can uniformly dissolve or disperse the alloy-based material (A), the carbon particles (B), and the binder (C). An aprotic polar solvent, more preferably an aprotic amide solvent. Examples of aprotic amide solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazo Lysinone etc. are included. These solvents may be used alone or in combination of two or more.

  In addition to these solvents, other solvents may coexist as necessary. Examples of other solvents are benzene, toluene, o-xylene, m-xylene, p-xylene, mesitylene, 1,2,4-trimethylbenzene, o-cresol, m-cresol, p-cresol, o-chloro. Toluene, m-chlorotoluene, p-chlorotoluene, o-bromotoluene, m-bromotoluene, p-bromotoluene, chlorobenzene, bromobenzene, methanol, ethanol, n-propanol, isopropyl alcohol and n-butanol are included. .

  The amount of solvent in the negative electrode mixture paste is appropriately set in consideration of the viscosity of the negative electrode mixture paste and the like. The amount of the solvent is preferably 50 parts by mass or more and 900 parts by mass or less, and more preferably 65 parts by mass or more and 500 parts by mass or less with respect to 100 parts by mass of the solid content contained in the composite paste.

  The negative electrode mixture paste can be applied by a known method such as screen printing, roll coating, or slit coating. At this time, the negative electrode mixture paste may be applied in a pattern, for example, a mesh-like negative electrode mixture layer may be formed.

  The applied negative electrode mixture paste can be dried by, for example, heat curing. Heat curing can usually be performed under atmospheric pressure, but may be performed under pressure or under vacuum. The atmosphere at the time of heating and drying is not particularly limited, but usually it is preferably performed in an atmosphere such as air, nitrogen, helium, neon or argon, more preferably in an atmosphere of nitrogen or argon which is an inert gas. The negative electrode mixture paste can be heated, for example, by heat treatment at 150 ° C. or more and 500 ° C. or less for 1 minute or more and 24 hours or less.

  If the content of each component of the negative electrode mixture layer is adjusted according to the amount of each component of the negative electrode mixture layer (pre-doped negative electrode mixture layer) in the negative electrode for a non-aqueous electrolyte secondary battery to be manufactured, Good. In addition, since the quantity of the linear polyphenylene compound (D) introduce | transduced into a negative electrode compound material layer at the time of pre dope is not so much with respect to the total mass of a negative electrode compound material layer, you may disregard.

  When the total volume of the alloy-based material (A) and the carbon particles (B) contained in the obtained negative electrode mixture layer is 100% by volume, the volume ratio of the alloy-based material (A) is 10% by volume or more and 60%. The volume is less than volume%, preferably 10 volume% or more and less than 40 volume%, more preferably 10 volume% or more and less than 30 volume%. When the volume ratio of the alloy material (A) is 10% by volume or more, the amount of alkali metals occluded by the pre-dope can be increased, and the amount of irreversible components to be generated can be decreased. As a result, the initial charge / discharge efficiency of the non-aqueous electrolyte secondary battery having the secondary battery negative electrode is increased, and the energy density is sufficiently increased. When the proportion of the volume of the alloy-based material (A) is less than 60% by volume, the pre-doping speed is high, so that the initial charge / discharge efficiency is increased, and the volume increase during pre-doping can be suppressed. The said volume ratio is measured by content and true specific gravity of an alloy type material (A) and a carbon particle (B). The contents of the alloy material (A) and the carbon particles (B) are specified by known methods such as electrochemical analysis, fluorescent X-ray analysis, ion chromatography, ICP mass spectrometry, and atomic absorption spectrophotometry. The On the other hand, the true specific gravity can be measured by a method according to JIS Z8807 using a solid sample (alloy material (A) and carbon particles (B)) pulverized into a powder form. It can be measured.

The dried pycnometer is left in a desiccator until it reaches room temperature, and the mass W1 of the pycnometer is weighed. A sufficiently pulverized sample (alloy material (A) or carbon particle (B)) is put in a pycnometer, and the mass W2 of (pycnometer + sample) is weighed. Further, n-butanol is put into the pycnometer so that the sample is sufficiently immersed, and the sample is sufficiently deaerated. Add more n-butanol to fill the pycnometer and place in a constant temperature bath to 25 ° C. After the n-butanol and the sample reach 25 ° C., the n-butanol meniscus is aligned with the marked line and allowed to stand at room temperature. Then, the mass W3 of (pycnometer + sample + n-butanol) is weighed. Fill the pycnometer only with n-butanol, put in a thermostatic bath to 25 ° C., align the meniscus of n-butanol with the marked line, let it stand until it reaches room temperature, and weigh the mass W4 of (Pycnometer + n-butanol).
The true specific gravity can be calculated as follows from the respective masses W1, W2, W3, and W4 weighed as described above.
True specific gravity = {(W2-W1) × s} / {(W2-W1)-(W3-W4)}
Here, s is the specific gravity of n-butanol at 25 ° C.

  The total amount of the alloy-based material (A) and the carbon particles (B) described later included in the negative electrode mixture layer is preferably 77% by mass or more and 97% by mass or less, and 80% by mass or more and 96% by mass. The following is more preferable. When the total amount of the alloy-based material (A) and the carbon particles (B) described later is in the above range, the amount of alkali metals that can be occluded and released is sufficiently increased, and the discharge capacity of the nonaqueous electrolyte secondary battery Can be made sufficiently large.

  The amount of the carbon particles (B) contained in the obtained negative electrode mixture layer is more than 40% by volume and 90% by volume when the total volume of the alloy-based material (A) and the carbon particles (B) is 100% by volume. %, Preferably more than 60 volume% and 90 volume% or less, more preferably more than 70 volume% and 90 volume% or less. As described above, when the alloy material (A) and the carbon particles (B) are within the above range, the amount of alkali metals occluded by the pre-doping is increased, and the amount of irreversible components to be generated is decreased. Can do. As a result, the initial charge / discharge efficiency of the non-aqueous electrolyte secondary battery having the secondary battery negative electrode is increased, and the energy density is sufficiently increased. Further, as described above, when the alloy-based material (A) and the carbon particles (B) are in the above range, an increase in volume during pre-doping can be suppressed. The volume ratio of the carbon particles (B) is calculated by the method described above.

  The amount of the binder (C) contained in the obtained negative electrode mixture layer is 4% by mass to 13% by mass and 5% by mass to 10% by mass with respect to the total mass of the negative electrode composite layer. Preferably, it is 5 mass% or more and 8 mass% or less. When the amount of the binder (C) is 4% by mass or more, the active materials or the active material and the current collector can be sufficiently bound. On the other hand, when the amount of the binder (C) is 13% by mass or less, the amount of alkali metals occluded by the pre-dope is increased, so that the first time of the non-aqueous electrolyte secondary battery having the negative electrode for secondary battery. Charge / discharge efficiency can be increased and energy density can be increased. The reason is not clear, but when the amount of the binder (C) is 13% by mass or less, the binder (C) does not completely cover the alloy material (A) or carbon particles (B) whose active material is used. It is presumed that when the alloy material (A) and the carbon particles (B) are partially exposed, the active material is easily pre-doped with alkali metals. The amount of the binder (C) can be calculated by the preparation amount at the time of preparing the negative electrode mixture layer, electrochemical analysis, fluorescent X-ray analysis, ion chromatography, ICP mass spectrometry, atomic absorption spectrophotometry, and the like. it can. Further, the binder can be quantified by immersing the electrode in a solvent in which the binder is dissolved and measuring the weight of the residue after removing the solvent.

  The amount of the conductive additive (E) contained in the obtained negative electrode mixture layer is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass. % Or more. Moreover, 20 mass% or less is preferable normally, More preferably, it is 10 mass% or less.

  The thickness of the obtained negative electrode mixture layer can be adjusted so that the finally obtained predoped negative electrode mixture layer has a thickness described later.

1-2. Pre-doping step A negative electrode mixture layer containing at least the alloy material (A), carbon particles (B), and binder (C) described above, and a dope solution containing a linear polyphenylene compound (D) and ions of alkali metals It is made to contact and the above-mentioned negative electrode compound layer is pre-doped with alkali metals. That is, a negative electrode having a negative electrode mixture layer containing predoped alkali metals is obtained. The method for bringing the negative electrode mixture layer into contact with the dope solution is not particularly limited, but it is preferable to immerse the negative electrode mixture layer in the dope solution and bring them into contact with the solution. Here, the alkali metals to be dissolved in the solution may be those that can occlude the alloy material (A).

  When an alkali metal and a linear polyphenylene compound (D) are dissolved in a solvent, electrons move from the alkali metal to the linear polyphenylene compound (D), and an anion and an alkali metal ion of the linear polyphenylene compound (D) ( For example, lithium ions or sodium ions) or alkaline earth metal ions are generated. When the negative electrode mixture layer is immersed in the above solution, electrons move from the anion of the linear polyphenylene compound (D) to the negative electrode mixture layer, and the anion of the linear polyphenylene compound (D) is a linear polyphenylene compound. Return to (D). On the other hand, the negative electrode active material (alloy material (A) and carbon atom (B)) that has received electrons reacts with alkali metal ions or alkaline earth metal ions, and the negative electrode active material is pre-doped with alkali metals. . At this time, the amount of the linear polyphenylene compound (D) described above is introduced into the negative electrode mixture layer.

(Preparation of dope solution)
The method for preparing the dope solution containing the linear polyphenylene compound (D) and alkali metal ions is not particularly limited. For example, after adding the alkali metals to the solvent in which the linear polyphenylene compound (D) is dissolved. , Stirring and reacting.

(Linear polyphenylene compound (D))
The linear polyphenylene compound (D) is a compound that functions as a catalyst when pre-doping the alloy material (A) and the carbon material (B), which are negative electrode active materials. The linear polyphenylene compound (D) is introduced into the negative electrode mixture layer when the alkali metal is pre-doped. Therefore, that the obtained negative electrode mixture layer contains the linear polyphenylene compound (D) means that the negative electrode is pre-doped by immersion in a solution containing ions of alkali metals and a catalyst.

  The linear polyphenylene compound (D) is a linear compound having a structure in which aromatic rings are bonded through a single bond. The structure in which the aromatic ring of the linear polyphenylene compound (D) is linearly bonded via a single bond preferably includes 2 or more and 5 or less aromatic rings, preferably 2 or more and 3 or less. More preferably, it contains an aromatic ring. The aromatic ring preferably does not contain a hetero atom. The linear polyphenylene compound (D) containing a structure in which two or more aromatic rings are bonded through a single bond has high activity of an association with lithium, and the amount of pre-doping to the electrode is improved. On the other hand, when the number of aromatic rings exceeds 5, the aggregate is stabilized and the pre-doping amount is reduced. Examples of the linear polyphenylene compound (D) include biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, and derivatives thereof. Examples of the derivatives include compounds in which biphenyl or terphenyl is substituted with an alkyl group having 1 to 10 carbon atoms, such as 4-tert-butylbiphenyl and 4,4′-di-tert-butylbiphenyl, p-methoxy. Biphenyl and the like are included. Among these, biphenyl, terphenyl or a derivative thereof is preferable.

(Alkali metals)
The alkali metal dissolved in the solvent is not particularly limited, but lithium, sodium, magnesium, potassium and calcium are preferable, lithium and sodium are more preferable, and lithium is particularly preferable. These alkali metals can be added to the solvent, for example, as a metal foil.

(solvent)
The kind of the solvent for dissolving the linear polyphenylene compound (D) and the alkali metal is not particularly limited as long as the alkali metal is easily solvated. For example, a cyclic carbonate, cyclic ester, chain ester, cyclic Ethers, chain ethers, nitriles and the like can be used.

  Examples of the cyclic carbonate include propylene carbonate, ethylene carbonate, dimethyl sulfoxide (DMSO) and the like. Examples of the cyclic ester include γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-hexanolactone, δ-octanolactone and the like. Examples of the chain ester include dimethyl carbonate (DMC), diethyl carbonate, ethyl methyl carbonate, and the like. Examples of the cyclic ether include oxetane, tetrahydrofuran, tetrahydropyran and the like. Examples of the chain ether include dimethoxyethane, ethoxymethoxyethane, diethoxyethane and the like. Examples of nitriles include acetonitrile, propionitrile, glutaronitrile, methoxyacetonitrile, 3-methoxypropionitrile and the like. The solvent may be hexamethylsulfurtriamide, acetone, N-methyl-2-pyrrolidone, dimethylacetamide, pyridine, dimethylformamide, ethanol, formamide, methanol, water, and the like. Only one of these may be included in the solvent, or two or more thereof may be included. Among these, cyclic ether is preferable and tetrahydrofuran is preferable.

(Physical properties of dope solution)
The content ratio of alkali metal ions or alkaline earth metal ions to the total number of moles of 100 mol% of the linear polyphenylene compound (D) in the dope solution is preferably 100 mol% or more and less than 150 mol%. When the content ratio is 100 mol% or more, the amount of alkali metal ions contained in the dope solution is sufficient, so that it is easy to increase the reactivity with the alloy material (A) in the negative electrode mixture layer, A sufficient amount of alkali metal ions can be pre-doped. When the content ratio is less than 150 mol%, the amount of the linear polyphenylene compound (D) contained in the dope solution is sufficient, and the bond between the alkali metal ions and the linear polyphenylene compound (D) is stabilized. Therefore, it is difficult to impair the catalytic action required for pre-doping, and the reactivity with the alloy-based material (A) in the negative electrode mixture layer is hardly impaired, so that a sufficient amount of alkali metal ions is pre-doped. Can do. The content ratio is more preferably 110 mol% or more and 130 mol% or less.

  The content ratio of alkali metal ions or alkaline earth metal ions to the total number of moles of 100 mol% of the linear polyphenylene compound (D) in the dope solution depends on the concentration of the linear polyphenylene compound (D) in the dope solution and the alkali metal ions. Alternatively, it can be calculated by measuring the concentration of alkaline earth metal ions. The concentration of the linear polyphenylene compound (D) in the dope solution can be calculated from the charged amount or measured by gas chromatography (GC) described later. The concentration of alkali metal ions or alkaline earth metal ions can be measured by ICP emission analysis.

  The content ratio depends on, for example, the stirring / reaction time after adding the alkali metal to the solvent in which the linear polyphenylene compound (D) is dissolved, the concentration of the linear polyphenylene compound (D) dissolved in the solvent, and the like. Can be adjusted. For example, the ion concentration of alkali metals in the solvent can be increased by lengthening the stirring and reaction time.

  The stirring / reaction time after adding the alkali metal to the solvent in which the linear polyphenylene compound (D) is dissolved is within a range in which the alkali metal can be sufficiently dissolved in the solvent without impairing the productivity. It is preferable. For example, the stirring / reaction time is preferably from 5 minutes to 2 hours, more preferably from 5 minutes to 60 minutes, and even more preferably from 15 minutes to 40 minutes. The stirring / reaction temperature is, for example, preferably 20 ° C. or more and 60 ° C. or less, more preferably 20 ° C. or more and 50 ° C. or less, and further preferably 20 ° C. or more and 40 ° C. or less.

  The concentration of the linear polyphenylene compound (D) in the dope solution is preferably from 0.1 mol / L to 4.0 mol / L, more preferably from 0.1 mol / L to 1.0 mol / L. More preferably, it is 0.1 mol / L or more and 0.7 mol / L or less. When the concentration of the linear polyphenylene compound (D) is 0.1 mol / L or more, it is easy to shorten the time required for pre-doping with alkali metals. On the other hand, when the concentration of the linear polyphenylene compound (D) is 4.0 mol / L or less, the linear polyphenylene compound (D) hardly precipitates in the solution.

The concentration of the linear polyphenylene compound (D) in the dope solution can be confirmed by gas chromatography (GC). Specifically, it can be confirmed by the following procedure.
1) Prepare a plurality of liquid samples having different concentrations of the linear polyphenylene compound (D), perform gas chromatography (GC) measurement under the measurement conditions described later, and obtain a calibration curve.
2) Next, the dope solution to be measured is analyzed by gas chromatography (GC), and the linear polyphenylene compound (D) in the dope solution is quantified by collating with the above calibration curve.
Gas chromatography (GC) can be performed, for example, under the following conditions.
Measuring device name: Agilent 7890A / 5975C GC / MSD
Column: Agilent J & W HP-5MS 60m long, 0.25mm inner diameter, 0.25μm film thickness
Heating conditions: 40 ° C. (3 minutes hold) −20 ° C./min. Temperature rise −300 ° C. (14 minutes hold)
Carrier gas: Helium Detector: MSD (mass selective detector)

In the spectrum obtained by measuring ⁷ Li-NMR of the dope solution at 20 ° C. or higher and 30 ° C. or lower, the main peak having a chemical shift value in the range of 3 ppm or more and 8 ppm or less exists in the range of peak A, 1 ppm or more and 5 ppm or less. When the minor peak to be used is peak B, the difference (A−B) in the chemical shift value between peak A and peak B is preferably more than 1.5 and less than 3. Peak A is a peak derived from activated lithium ions (specifically, lithium ions whose bond with the linear polyphenylene compound (D) is not stabilized), and peak B is non-activated lithium ions (specifically Specifically, it is a peak derived from a stabilized lithium ion with the linear polyphenylene compound (D). Necessary for pre-doping because the difference in chemical shift value between peak A and peak B (AB) is more than 1.5, the bonding state between the linear polyphenylene compound (D) and lithium ions is not overstabilized. When the amount is less than 3, the activated lithium ion amount is sufficient, and the reactivity with the alloy-based material (A) in the negative electrode mixture layer is easily increased.

  The main peak having a chemical shift value in a range of 3 ppm or more and 8 ppm or less means a peak having the highest peak intensity among peaks having a chemical shift value in a range of 3 ppm or more and 8 ppm or less. The minor peak having a chemical shift value in the range of 1 ppm or more and 5 ppm or less is a peak in which the chemical shift value is in the range of 1 ppm or more and 5 ppm or less, and the chemical shift value is lower than the main peak. The one with the highest peak intensity.

⁷ Li-NMR measurement can be performed by the following method.
1) A standard (1M LiCl / D ₂ O) solution is prepared, and nuclear magnetic resonance (NMR) measurement is performed under the measurement conditions described later to obtain a chemical shift reference.
2) Next, a solution of the linear polyphenylene compound (D) to be measured is put into an NMR sample tube, and nuclear magnetic resonance (NMR) measurement is performed under the measurement conditions described later. The obtained spectrum is subjected to peak separation by Lorentz function distribution, and the center value and area of each peak are obtained by collating with the above-mentioned chemical shift standard.
Nuclear magnetic resonance (NMR) can be performed under the following conditions.
Measurement apparatus name: ECA500 type nuclear magnetic resonance apparatus manufactured by JEOL Measurement nucleus: ⁷ Li (194 MHz)
Measurement mode: Single pulse Pulse width: 45 ° (6.00 μsec)
Number of points: 32k
Observation range: 50 ppm (-25 ppm to 25 ppm)
Repetition time: 7.0 seconds Integration count: 128 times Measurement solvent: Neat
Measurement temperature Room temperature: (22 ℃)
Window function: exponential (BF: 0.2Hz)
Chemical shift standard: 1M LiCl / D ₂ O: 0.00 ppm
3) The chemical shift value obtained from the thus verified spectrum is the chemical shift value, the main peak existing in the range of 3 ppm to 8 ppm as peak A, the minor peak existing in the range of 1 ppm to 5 ppm as peak B, and the chemical shift. The difference between the values is obtained as AB.

  The difference (A−B) in the chemical shift value between peak A and peak B can be adjusted by the stirring / reaction time (or ion concentration of alkali metal) during preparation of the dope solution and the concentration of the linear polyphenylene compound (D). . In order to make the difference (A-B) in the chemical shift value more than a certain value, for example, the stirring / reaction time (or the ion concentration of alkali metals) is preferably made less than a certain value, and the linear polyphenylene compound (D) The concentration of is preferably set to a certain level.

(Pre-doping conditions)
The time for contacting the dope solution and the negative electrode mixture layer is not particularly limited. In order to fully pre-dope alkali metals into the negative electrode active material (alloy material (A) and carbon atom (B)), it is preferably 0.5 minutes or more, and 0.5 minutes or more and 240 hours or less. It is preferably 0.5 minutes or more and 72 hours or less, more preferably 0.5 minutes or more and 24 hours or less, further preferably 0.5 minutes or more and 1 hour or less, More preferably, it is 0.5 minutes or more and 0.5 hours or less.

  When the negative electrode is immersed in the solution, the alkali metal pre-doping rate can be increased by flowing the solution by stirring or circulation. In addition, although the pre-doping speed can be increased by increasing the temperature of the solution, it is preferable to set the temperature to be equal to or lower than the boiling point of the solvent in order not to boil the solution.

1-3. Step for removing impurities from negative electrode for secondary battery In this step, the negative electrode for secondary battery obtained in the above-mentioned step was pre-doped by dipping in a solvent in which the linear polyphenylene compound (D) is soluble. The linear polyphenylene compound (D) is removed from the negative electrode mixture layer. By removing the linear polyphenylene compound (D) by this step, impurities in the secondary battery negative electrode are reduced, and the stability of the nonaqueous electrolyte secondary battery is increased. The linear polyphenylene compound (D) is not completely removed from the predoped negative electrode mixture layer, and at least the above-mentioned amount remains in the predoped negative electrode mixture layer.

  Examples of the solvent in which the linear polyphenylene compound (D) is soluble include the aforementioned cyclic carbonates, cyclic esters, chain esters, cyclic ethers, chain ethers, nitriles, and the like. Among these, from the viewpoint of lithium solubility, a cyclic carbonate is preferable, and tetrahydrofuran is more preferable. The time for immersing the negative electrode mixture layer in the solvent is not particularly limited, and may be 5 seconds or more, and preferably 10 seconds or more and 10 hours or less. A stable negative electrode for a nonaqueous electrolyte secondary battery can be obtained by sufficiently evaporating the solvent after immersion in the solvent. In addition, when the negative electrode mixture layer is immersed in the solution, the linear polyphenylene compound (D) can be easily removed and the removal rate of impurities can be increased by causing the solution to flow or slightly vibrate with ultrasonic waves. it can. Even if the temperature of the solution is increased, the removal rate of impurities can be increased, but in order not to boil the solution, the temperature of the solution during heating is preferably set to a temperature not higher than the boiling point of the solvent.

1-4. Negative electrode The negative electrode for a non-aqueous electrolyte secondary battery obtained by the method for producing a negative electrode for a non-aqueous electrolyte secondary battery of the present invention (hereinafter, also simply referred to as “secondary battery negative electrode”) is the above-described alloy material (A ), Carbon particles (B), binder (C), and linear polyphenylene compound (D), and at least a part of the alloy-based material (A) contains pre-doped alkali metals. It has a negative electrode mixture layer (a pre-doped negative electrode mixture layer). The secondary battery negative electrode may further include a current collector. The structure of the negative electrode for the secondary battery can be appropriately selected according to the application of the nonaqueous electrolyte secondary battery to be applied. For example, the negative electrode for the secondary battery is disposed on both sides of the sheet-like current collector and the current collector. It can be set as the laminated body etc. which consist of the said predoped negative electrode compound-material layer. The negative electrode for a secondary battery can also be used as an electrode of a capacitor such as a lithium ion capacitor.

(Pre-doped negative electrode mixture layer)
The predoped negative electrode mixture layer includes at least an alloy material (A), carbon particles (B), a binder (C), and a linear polyphenylene compound (D).

  The thickness of the pre-doped negative electrode mixture layer is not particularly limited, and is preferably, for example, 5 μm or more, more preferably 10 μm or more. The thickness of the negative electrode mixture layer is preferably 200 μm or less, more preferably 100 μm or less, and still more preferably 75 μm or less. When the thickness of the negative electrode mixture layer is in the above range, the amount of alkali metals capable of occlusion and release can be sufficiently increased even for charge / discharge at a high charge / discharge rate.

The density of the predoped negative electrode mixture layer is preferably 1.1 g / cm ³ or more and 1.7 g / cm ³ or less, more preferably 1.2 g / cm ³ or more and 1.5 g / cm ³ or less. Preferably, it is 1.2 g / cm ³ or more and 1.4 g / cm ³ or less. When the density of the active material in the negative electrode mixture layer is 1.1 g / cm ³ or more, the volume energy density of the battery is easily increased sufficiently, and when it is 1.6 g / cm ³ or less, cycle characteristics are easily increased.

Further, when the pre-doped negative electrode mixture layer is formed on both surfaces of the current collector, the active material (alloy material (A) and carbon particles (per unit area) included on one side of the negative electrode mixture layer ( the amount of B)) is more preferably is at 2 mg / cm ² or more 10 mg / cm ² or less is preferable, 3 mg / cm ² or more 8 mg / cm ² or less.

  The amount of each component of the pre-doped negative electrode mixture layer corresponds to the content of each component of the negative electrode mixture layer before pre-doping. That is, when the total volume of the alloy-based material (A) and the carbon particles (B) contained in the predoped negative electrode mixture layer is 100% by volume, the volume ratio of the alloy-based material (A) is 10 volumes. % Or more and less than 60% by volume, preferably 10% by volume or more and less than 40% by volume, more preferably 10% by volume or more and less than 30% by volume. As described above, when the volume ratio of the alloy material (A) is 10% by volume or more, the amount of alkali metals occluded by the pre-dope is increased and the amount of irreversible components to be generated is decreased. Can do. As a result, the initial charge / discharge efficiency of the non-aqueous electrolyte secondary battery having the secondary battery negative electrode is increased, and the energy density is sufficiently increased. When the proportion of the volume of the alloy-based material (A) is less than 60% by volume, the pre-doping speed is high, so that the initial charge / discharge efficiency is increased, and the volume increase during pre-doping can be suppressed.

  The amount of the carbon particles (B) in the predoped negative electrode mixture layer is more than 40% by volume and 90% by volume when the total volume of the alloy-based material (A) and the carbon particles (B) is 100% by volume. It is preferable that it is more than 60 volume% and 90 volume% or less, and more preferably more than 70 volume% and 90 volume% or less. As described above, when the alloy material (A) and the carbon particles (B) are within the above range, the amount of alkali metals occluded by the pre-doping is increased, and the amount of irreversible components to be generated is decreased. Can do. As a result, the initial charge / discharge efficiency of the non-aqueous electrolyte secondary battery having the secondary battery negative electrode is increased, and the energy density is sufficiently increased. Further, as described above, when the alloy-based material (A) and the carbon particles (B) are in the above range, an increase in volume during pre-doping can be suppressed.

  The amount of the binder (C) contained in the pre-doped negative electrode mixture layer is 4% by mass to 13% by mass, and 5% by mass to 10% by mass with respect to the total mass of the negative electrode composite layer. It is preferably 5% by mass or more and 8% by mass or less. As described above, when the amount of the binder (C) is 4% by mass or more, the active materials or the active material and the current collector can be sufficiently bound. On the other hand, when the amount of the binder (C) is 13% by mass or less, the amount of alkali metals occluded by the pre-dope is increased, so that the first time of the non-aqueous electrolyte secondary battery having the negative electrode for secondary battery. Charge / discharge efficiency can be increased and energy density can be increased.

In the case of a single-sided electrode, the amount of the linear polyphenylene compound (D) contained in the predoped negative electrode mixture layer is preferably 0.005 μg or more and 20 μg or less, and 0.005 μg or more and 10 μg per electrode area (cm ² ). Or less, more preferably 0.005 μg or more and 5 μg or less. In the case of a double-sided electrode, the amount of the linear polyphenylene compound (D) is preferably 0.01 μg or more and 40 μg or less, more preferably 0.01 μg or more and 20 μg or less per electrode area (cm ² ). More preferably, it is 01 μg or more and 10 μg or less. When the linear polyphenylene compound (D) is present in a large amount, when the negative electrode is used for a non-aqueous electrolyte secondary battery, the internal resistance of the battery may increase, or the initial characteristics and load characteristics may decrease. On the other hand, when the amount of the linear polyphenylene compound (D) is in the above range, the linear polyphenylene compound (D) hardly affects the characteristics of the battery, and the battery characteristics are easily stabilized.

The amount of the linear polyphenylene compound (D) contained in the predoped negative electrode mixture layer can be confirmed by gas chromatography (GC). Specifically, it can be confirmed by the following procedure.
1) The linear polyphenylene compound (D) in the pre-doped negative electrode mixture layer is specified by gas chromatography (GC). And several liquid samples from which the density | concentration of the specified linear polyphenylene compound (D) differs are prepared, a gas chromatography (GC) measurement is performed on the measurement conditions mentioned later, and a calibration curve is obtained.
2) Next, the pre-doped negative electrode mixture layer to be measured is placed in a vial, and 1 mL of an extraction solvent in which the linear polyphenylene compound (D) is soluble is added thereto and immersed for 30 minutes. This vial is set in an ultrasonic cleaning machine VS-D100 (manufactured by ASONE), and the vial is irradiated with a composite frequency of 24 kHz and 31 kHz for 3 minutes.
3) The obtained extraction solvent is analyzed by gas chromatography (GC), and the linear polyphenylene compound (D) in the extraction solvent is quantified by collating with the above-mentioned calibration curve.
Gas chromatography (GC) can be performed, for example, under the following conditions.
Measuring device name: Agilent 7890A / 5975C GC / MSD
Column: Agilent J & W HP-5MS 60m long, 0.25mm inner diameter, 0.25μm film thickness
Heating conditions: 40 ° C. (3 minutes hold) −20 ° C./min. Temperature rise −300 ° C. (14 minutes hold)
Carrier gas: Helium Detector: MSD (mass selective detector)

  The extraction solvent is not particularly limited as long as it is a solvent in which the linear polyphenylene compound (D) is dissolved, but a low boiling point solvent that is easily vaporized is preferable. An example of such an extraction solvent includes acetone.

  The pre-doped negative electrode mixture layer preferably contains 0.01% by mass or more of the conductive additive (E), more preferably 0.05% by mass or more, and further preferably 0.1% by mass. That's it. Moreover, 20 mass% or less is preferable normally, More preferably, it is 10 mass% or less.

(Current collector)
The shape of the current collector of the negative electrode is appropriately selected according to the use of the nonaqueous electrolyte secondary battery. For example, when the current collector is made of a metal material, it may be in the form of a foil, a column, a coil, a plate, a thin film, or the like. On the other hand, when the current collector is made of a carbon material, it may have a plate shape, a thin film shape, a cylindrical shape, or the like. The thickness of the current collector is not particularly limited, but is usually 5 μm or more and 30 μm or less, and preferably 6 μm or more and 20 μm or less. Further, the current collector surface may be roughened by chemical treatment or physical treatment, or may be one obtained by applying a conductive material such as carbon black or acetylene black to the surface.

  In the present embodiment, a method of obtaining a negative electrode mixture layer containing a pre-doped alkali metal by contacting a negative electrode mixture layer containing a negative electrode active material such as an alloy-based material (A) with a dope solution will be described. However, the present invention is not limited to this, and after bringing a negative electrode active material such as an alloy-based material (A) into contact with the dope solution, the negative electrode active material layer is used to form a negative electrode mixture layer containing alkali metals pre-doped. You may get

  That is, in the method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery according to the present invention, a negative electrode active material made of an alloy-based material (A) containing silicon or tin capable of occluding alkali metals is converted into a linear polyphenylene compound ( A step of obtaining a negative electrode active material (A) ′ containing pre-doped alkali metals by contacting with a dope solution containing D) and alkali metal ions;

  The alloy material (A) used in the method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery of the present invention can be the same as the alloy material (A) in the above-described embodiment. In addition, as the dope solution to be brought into contact with the alloy-based material (A), the same dope solution as that to be brought into contact with the negative electrode mixture layer in the above-described embodiment can be used, and the method for producing the dope solution in the above-mentioned embodiment -It can be manufactured in the same manner as the conditions. By using such a dope solution, a large amount of alkali metals can be pre-doped in a relatively short time in the negative electrode active material as in the above-described embodiment.

  The negative electrode active material (A) ′ obtained by the method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery of the present invention is widely used for the production of a negative electrode mixture layer. The negative electrode composite material layer can be produced in the same manner as in step 1) in the above-described embodiment. For example, the obtained negative electrode active material (A) ′, carbon particles (B), binder (C), and conductive auxiliary agent (E) as necessary are dispersed in a solvent to obtain a negative electrode mixture paste. It can be obtained by applying to a current collector. The carbon particles (B), binder (C), and conductive auxiliary (E) used are the same as the carbon particles (B), binder (C), and conductive auxiliary (E) in the above-described embodiments, respectively. Can be used. The composition of the obtained negative electrode mixture layer can be the same as the composition of the negative electrode mixture layer obtained in the above-described embodiment.

2. Method for Producing Nonaqueous Electrolyte Secondary Battery The method for producing a nonaqueous electrolyte secondary battery according to the present invention includes a step of obtaining a negative electrode by the above-described method for producing a negative electrode for a nonaqueous electrolyte secondary battery, or the above nonaqueous electrolyte secondary battery. A step of obtaining a negative electrode using a negative electrode active material obtained by a method for producing a negative electrode active material for use (preferably a step of obtaining a negative electrode by a method for producing a negative electrode for a nonaqueous electrolyte secondary battery as described above), and the obtained negative electrode and positive electrode And a step of obtaining a non-aqueous electrolyte secondary battery provided with an electrolytic solution.

  A non-aqueous electrolyte secondary battery can be manufactured by assembling the negative electrode for a secondary battery obtained by the above-described manufacturing method, the positive electrode, and the like in an appropriate procedure according to the structure of the battery. For example, the above-mentioned negative electrode for a secondary battery is placed on an outer case, an electrolytic solution and a separator are provided thereon, and a positive electrode is placed so as to face the negative electrode, and is caulked together with a gasket and a sealing plate. Can do.

  The form of the non-aqueous electrolyte secondary battery is not particularly limited, but examples thereof include a cylinder type in which a sheet electrode and a separator are spiral, a cylinder type having an inside-out structure in which a pellet electrode and a separator are combined, a pellet electrode and a separator A coin type with stacked layers is included. Moreover, it is good also as arbitrary shapes, such as a coin shape, a cylindrical shape, a square shape, and a pouch shape, by accommodating the battery of these forms in arbitrary exterior cases.

  The non-aqueous electrolyte secondary battery thus obtained includes a positive electrode, the above-described negative electrode for a secondary battery, and an electrolytic solution. The negative electrode of the non-aqueous electrolyte secondary battery is pre-doped with alkali metals. Therefore, “the total molar amount of alkali metals contained in the secondary battery negative electrode at full charge” is larger than “the molar amount of alkali metals calculated from the capacity of the positive electrode active material of the positive electrode”. “Molar amount of alkali metals calculated from capacity of positive electrode active material”, “Total molar amount of alkali metals contained in negative electrode at full charge”, and “Amount of alkali metals pre-doped to negative electrode” It can be verified by the following method.

  The “total molar amount of alkali metals contained in the negative electrode when fully charged” can be identified by an element quantitative analysis method such as an ICP emission analysis method or an atomic absorption method. The total molar amount is “molar amount of alkali metal contributing to charge / discharge of positive electrode active material (B)” and “alkali metal in negative electrode for secondary battery (alkali metal pre-doped on negative electrode)”. Corresponds to the total (A).

  On the other hand, “molar amount of alkali metal calculated from the capacity of the positive electrode active material” is a half cell having a positive electrode of a nonaqueous electrolyte secondary battery and a counter electrode of the alkali metal, and the discharge capacity of the half cell (positive electrode). It can be identified by measuring the amount of alkali metal occlusion in Since the above value corresponds to the above “molar amount of alkali metal contributing to charge / discharge of positive electrode active material (B)”, by subtracting (B) from (A), “pre-doped to negative electrode” The amount of alkali metals can be specified.

  In the non-aqueous electrolyte secondary battery of the present invention, the negative electrode for the secondary battery is 3 mol% or more with respect to the aforementioned “molar amount of alkali metals calculated from the capacity of the positive electrode active material possessed by the positive electrode”. It is preferable that 50 mol% or less, preferably 7 mol% or more and 40 mol% or less, more preferably 10 mol% or more and 35 mol% or less of alkali metal is pre-doped. When the total molar amount of alkali metal and alkaline earth metal contained in the negative electrode for secondary battery is in the above range, the negative electrode for secondary battery is stable, there is little decrease in the dope capacity over time, and other than in an inert atmosphere. A non-aqueous electrolyte secondary battery can be assembled. When the total molar amount of alkali metals is less than 3 mol%, the initial charge / discharge efficiency of the battery is not sufficiently improved. On the other hand, if it is larger than 50 mol%, the activity of the negative electrode is increased, and it becomes necessary to assemble the battery in an inert atmosphere such as argon, which is not practical.

  In addition, since it mentioned above about the said negative electrode for secondary batteries, it demonstrates below about the positive electrode, electrolyte solution, and separator which are structures other than the negative electrode of a nonaqueous electrolyte secondary battery.

2-1. Positive electrode The positive electrode can be appropriately selected according to the use of the nonaqueous electrolyte secondary battery. For example, a laminate composed of a sheet-like current collector and a positive electrode mixture layer disposed on both surfaces of the current collector It can be a body or the like.

(Positive electrode mixture layer)
The positive electrode mixture layer may be a layer in which a positive electrode active material is bound by a positive electrode binder (positive electrode binder). The positive electrode active material is not limited as long as the alloy-based material (A) that the negative electrode for secondary battery has in the negative electrode mixture layer is a material that can occlude and release alkali metals that can be occluded and released. A positive electrode active material usually used for an electrolyte secondary battery can be used. Specifically, when the alkali metal is lithium, a lithium-manganese composite oxide (such as LiMn ₂ O ₄ ), a lithium-nickel composite oxide (such as LiNiO ₂ ), or a lithium-cobalt composite oxide (LiCoO _2). Etc.), lithium-iron composite oxide (LiFeO ₂ etc.), lithium-nickel-manganese composite oxide (LiNi _0.5 Mn _0.5 O ₂ etc.), lithium-nickel-cobalt composite oxide (LiNi _0.8). Co _0.2 O ₂ ), lithium-nickel-cobalt-manganese composite oxide, lithium-transition metal phosphate compound (such as LiFePO ₄ ), and lithium-transition metal sulfate compound (Li _x Fe ₂ (SO ₄ ) ₃ ) And the like.

  The alkali metal that can be occluded and released by the alloy material (A), the alkali metal that has been pre-doped in the pre-doping step, and the alkali metal that can be occluded and released by the positive electrode active material are the same elements. It is preferable that

  Only one kind of these positive electrode active materials may be contained in the positive electrode mixture layer, or two or more kinds thereof may be contained. The amount of the positive electrode active material in the positive electrode mixture layer may be 10% by mass or more, preferably 30% by mass or more, and more preferably 50% by mass or more. Moreover, the quantity of the positive electrode active material in a positive electrode compound-material layer should just be 99.9 mass% or less, and it is preferable that it is 99 mass% or less.

On the other hand, the positive electrode binder for binding the positive electrode active material may be a binder (binder (C)) or the like contained in the negative electrode mixture layer, but other known positive electrode binders. It can also be a resin. Examples of known positive electrode binder resins include inorganic compounds such as silicate and water glass, and polymers having no unsaturated bond such as Teflon (registered trademark), polyvinylidene fluoride, and polyimide. The lower limit of the weight average molecular weight of these polymers may be 1.0 × 10 ⁴ , and is preferably 1.0 × 10 ⁵ . The upper limit of the weight average molecular weight of these polymers may be 3.0 × 10 ⁶ , and is preferably 1.0 × 10 ⁶ .

  In order to improve the electroconductivity of an electrode, the conductive support agent may be contained in the positive mix layer. The conductive auxiliary agent is not particularly limited as long as it can impart conductivity, and may be carbon powder such as acetylene black, carbon black, and graphite, various metal fibers, powder, foil, and the like.

The thickness of the positive electrode mixture layer may be 10 μm or more and 200 μm or less. The density of the positive electrode mixture layer (calculated from the mass and thickness of the positive electrode mixture layer per unit area laminated on the current collector) is 3.0 g / cm ³ or more and 4.5 g / cm ³ or less. Is preferred.

(Positive electrode current collector)
As the current collector for the positive electrode, metal materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, and carbon materials such as carbon cloth and carbon paper can be used. Of these, metal materials are preferred, and aluminum is particularly preferred. When the current collector is made of a metal material, the shape of the current collector can be a foil shape, a columnar shape, a coil shape, a plate shape, or a thin film shape. The current collector may be in the form of a mesh or the like, and may be made of expanded metal, punch metal, foam metal, or the like. On the other hand, when the current collector is made of a carbon material, the shape can be a plate shape, a thin film shape, a cylinder shape, or the like. Among these, metal thin films are preferable because they are currently used in industrialized products.

  When the positive electrode current collector is a thin film, the thickness is arbitrary, but it can be 1 μm or more, preferably 3 μm or more, and more preferably 5 μm or more. The thickness may be 100 mm or less, preferably 1 mm or less, and more preferably 50 μm or less. If the thickness of the positive electrode current collector that is a thin film is thinner than the above range, the strength required for the current collector may be insufficient. On the other hand, when the thickness of the positive electrode current collector as a thin film is thicker than the above range, the ease of handling may be impaired.

(Method for forming positive electrode)
The positive electrode described above is obtained by dispersing the positive electrode active material, positive electrode binder or precursor thereof, and a conductive additive in a solvent to form a positive electrode mixture paste, which is applied to a current collector. . After the application of the positive electrode mixture paste, the positive electrode mixture paste is dried and solidified by removing the solvent or reacting the positive electrode binder as necessary. The method for applying and solidifying the positive electrode mixture paste can be the same as the method for forming the negative electrode.

2-2. Electrolyte Solution The electrolyte solution of the nonaqueous electrolyte secondary battery of the present invention may be a nonaqueous electrolyte solution obtained by dissolving the alkali metal salt in a nonaqueous solvent. Further, it may be a gel, rubber, or solid sheet obtained by adding an organic polymer compound or the like to this non-aqueous electrolyte solution.

The non-aqueous electrolyte includes an alkali metal salt and a non-aqueous solvent. The alkali metal salt can be appropriately selected from known alkali metal salts. For example, when the alkali metal is lithium, halides such as LiCl and LiBr, perhalogenates such as LiBrO ₄ and LiClO ₄ , inorganic fluoride salts such as LiPF ₆ , LiBF ₄ , and LiAsF ₆ , lithium bis ( Oxalatoborate) Inorganic lithium salts such as LiBC ₄ O ₈ , perfluoroalkane sulfonates such as LiCF ₃ SO ₃ and LiC ₄ F ₉ SO ₃ , Li trifluorosulfonimide ((CF ₃ SO ₂ ) ₂ NLi), etc. Fluorine-containing organic lithium salt such as perfluoroalkanesulfonic acid imide salt. The electrolytic solution may contain only one kind of alkali metal salt or two or more kinds thereof. The concentration of the alkali metal salt in the non-aqueous electrolyte can be 0.5 M or more and 2.0 M or less.

  Examples of non-aqueous solvents include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), cyclic carbonates such as vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Chain carbonates such as methyl carbonate (EMC) and dipropyl carbonate (DPC), aliphatic carboxylic acid esters such as methyl formate, methyl acetate, methyl propionate and ethyl propionate, and γ-lactones such as γ-butyrolactone Chain ethers such as 1,2-dimethoxyethane (DME), 1,2-diethoxyethane (DEE) and ethoxymethoxyethane (EME), cyclic ethers such as tetrahydrofuran and 2-methyltetrahydrofuran, dimethylsulfate Hoxide, 1,3-dioxolane, formamide, acetamide, dimethylformamide, dioxolane, acetonitrile, propylnitrile, nitromethane, ethyl monoglyme, phosphate triester, trimethoxymethane, dioxolane derivative, sulfolane, methylsulfolane, 1,3-dimethyl -2-imidazolidinone, 3-methyl-2-oxazolidinone, propylene carbonate derivative, tetrahydrofuran derivative, ethyl ether, 1,3-propane sultone, anisole, dimethyl sulfoxide, N-methylpyrrolidone, butyl diglyme, methyl tetraglyme And aprotic organic solvents. These electrolytes may contain only one kind or two or more kinds.

  Specific examples of the organic polymer compound for making the electrolyte into a gel, rubber or solid sheet include polyether polymer compounds such as polyethylene oxide and polypropylene oxide, polyether polymer compounds Cross-linked polymers, vinyl alcohol polymer compounds such as polyvinyl alcohol and polyvinyl butyral, insolubilized products of vinyl alcohol polymer compounds, polyepichlorohydrin, polyphosphazene, polysiloxane, polyvinyl pyrrolidone, polyvinylidene carbonate, polyacrylonitrile and other vinyl Polymer compounds, poly (ω-methoxyoligooxyethylene methacrylate), poly (ω-methoxyoligooxyethylene methacrylate-co-methyl methacrylate), poly (hexafluoropropylene-fluorinated) Polymer copolymers such as vinylidene).

  The electrolytic solution may further contain a film forming agent. Specific examples of the film forming agent include vinylene carbonate, vinyl ethylene carbonate, vinyl ethyl carbonate, methyl phenyl carbonate and other carbonate compounds, fluoroethylene carbonate, difluoroethylene carbonate, trifluoromethyl ethylene carbonate, bis (trifluoromethyl) ethylene carbonate. 1-fluoroethyl methyl carbonate, ethyl 1-fluoroethyl carbonate, fluoromethyl methyl carbonate, bis (1-fluoroethyl) carbonate, bis (fluoromethyl) carbonate, ethyl 2-fluoroethyl carbonate, bis (2-fluoroethyl) Carbonate, methyl 1,1,1-trifluoropropan-2-yl carbonate, ethyl 1,1,1-trifluoropro N-2-yl carbonate, methyl 2,2,2-trifluoroethyl carbonate, bis (1,1,1-trifluoropropan-2-yl) carbonate, bis (2,2,2-trifluoroethyl) carbonate , Fluorine-based carbonate compounds such as ethyl 3,3,3-trifluoropropyl carbonate, bis (3,3,3-trifluoropropyl) carbonate, alkene sulfides such as ethylene sulfide and propylene sulfide, 1,3-propane sultone, Examples include sultone compounds such as 1,4-butane sultone, and acid anhydrides such as maleic anhydride and succinic anhydride.

  When a film forming agent is contained in the electrolytic solution, the content thereof may be 30% by mass or less, preferably 15% by mass or less, and preferably 10% by mass with respect to the total amount (mass) of the components of the electrolytic solution. % Or less is more preferable, and 2% by mass or less is particularly preferable. When the content of the film forming agent is too large, other battery characteristics such as an increase in initial irreversible capacity, low temperature characteristics, and rate characteristics of the nonaqueous electrolyte secondary battery may be adversely affected.

2-3. Separator A separator may be included between the positive electrode and the negative electrode for a secondary battery. When a separator is included, a short circuit between the electrodes is prevented. The separator can be a porous body such as a porous film or a nonwoven fabric. Although the porosity of a separator is suitably set according to the permeability | transmittance of an electron or ion, the raw material of a separator, etc., it is preferable that they are 30% or more and 80% or less.

  Examples of the separator include a microporous film having excellent ion permeability, a glass fiber sheet, a nonwoven fabric, and a woven fabric. Further, from the viewpoint of enhancing the organic solvent resistance and hydrophobicity, the separator material is preferably polypropylene, polyethylene, polyphenylene sulfide, polyethylene terephthalate, polyethylene naphthalate, polymethylpentene, polyamide, polyimide, or the like. A separator may consist only of these 1 type, and may consist of 2 or more types.

  An inexpensive polypropylene can be used for the separator. When the non-aqueous electrolyte secondary battery is required to have reflow resistance, the separator is preferably made of polypropylene sulfide, polyethylene terephthalate, polyamide, polyimide, or the like having a heat distortion temperature of 230 ° C. or higher. Moreover, the thickness of a separator can be 10 micrometers or more and 300 micrometers or less.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited to the description of the examples.

The contents of the abbreviations used in the examples and comparative examples are shown below.
PAALi: Polyacrylic acid neutralized with Li THF: Tetrahydrofuran BP: Biphenyl NAP: Naphthalene

  The measuring methods of various physical properties in the examples and comparative examples are as follows.

(Solid content concentration of carboxylate-containing polymer (C2))
The carboxylate-containing polymer (C2) (whose mass is w ₁ ) was heat-treated in a hot air dryer at 150 ° C. for 60 minutes, and the mass after the heat treatment (its mass is designated as w ₂ ) was measured. . The solid content concentration (% by mass) was calculated by the following formula.
Solid content concentration (% by mass) = (w ₂ / w ₁ ) × 100

(Lithium ion concentration of dope solution and molar ratio of lithium ion to linear polyphenylene compound (D))
1) A dope solution prepared in each example or comparative example was prepared. To this dope solution, sulfuric acid and nitric acid were added and heated to decompose the organic matter, and then diluted with ion-exchanged water to obtain a test solution.
2) The obtained test solution was analyzed with an inductively coupled plasma (ICP) emission spectroscopic analyzer under the measurement conditions described later, and the concentration of lithium ions in the extraction solution was quantified. Inductively coupled plasma (ICP) emission spectrometry was performed, for example, under the following conditions.
Measurement device name: 720-ES (manufactured by Agilent Technologies)
Measurement conditions: Followed the instrument operation manual of Agilent Technologies.
Detector: Multi-channel CCD
3) The lithium ion concentration determined in this way is divided by the concentration of the linear polyphenylene compound in the dope solution (concentration calculated from the charged amount), and the molar ratio of the lithium ion to the linear polyphenylene compound is calculated. Asked.

( ⁷ Li-NMR measurement of dope solution)
1) A standard (1M LiCl / D ₂ O) solution was prepared, and nuclear magnetic resonance (NMR) measurement was performed under the measurement conditions described later to obtain a chemical shift reference.
2) Next, a solution of the linear polyphenylene compound (D) to be measured was placed in an NMR sample tube, and nuclear magnetic resonance (NMR) measurement was performed under the measurement conditions described later. The obtained spectrum was subjected to peak separation by Lorentz function distribution, and the center value and area of each peak were obtained by collating with the above-mentioned chemical shift standard. Nuclear magnetic resonance (NMR) was performed under the following conditions.
Measurement apparatus name: ECA500 type nuclear magnetic resonance apparatus manufactured by JEOL Measurement nucleus: ⁷ Li (194 MHz)
Measurement mode: Single pulse Pulse width: 45 ° (6.00 μsec)
Number of points: 32k
Observation range: 50 ppm (-25 ppm to 25 ppm)
Repetition time: 7.0 seconds Integration count: 128 times Measurement solvent: Neat
Measurement temperature: Room temperature (22 ° C)
Window function: exponential (BF: 0.2Hz)
Chemical shift standard: 1M LiCl / D ₂ O: 0.00 ppm
3) The chemical shift value obtained from the thus verified spectrum is the chemical shift value, the main peak existing in the range of 3 ppm to 8 ppm as peak A, the minor peak existing in the range of 1 ppm to 5 ppm as peak B, and the chemical shift. The difference in values was obtained as AB.

(Negative electrode capacity, initial charge / discharge efficiency)
The negative electrode capacity and the initial charge / discharge efficiency were evaluated using a coin cell. As the electrode, a negative electrode having a diameter of 14.5 mmΦ and a positive electrode made of a lithium foil having a diameter of 15 mmΦ were used. As the electrolytic solution, a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio 1: 1 mixing) was used. As the separator, a polypropylene porous film having a diameter of 16 mmΦ and a film thickness of 25 μm was used.

These coin cells were allowed to stand at 25 ° C. for 24 hours and then charged at a constant current until the voltage reached 3 V at a measurement temperature of 25 ° C. and 0.05 C. First, the coin cell was allowed to stand for 10 minutes, and then a constant current discharge was performed until it reached 0.005 V, and then a constant voltage discharge was performed until 0.01 C. Next, the discharged coin cell was allowed to stand for 10 minutes, and then was charged with a constant current until it became 0.05 V and 1.2 V in the CC mode. The discharge capacity at the time of charge / discharge was defined as the capacity at the time of lithium insertion into the negative electrode, and the charge capacity carried out after the discharge was defined as the capacity at the time of lithium desorption. The initial charge / discharge efficiency was calculated by the following equation.
Initial charge / discharge efficiency (%) = Lithium desorption capacity / Lithium insertion capacity * 100

(Negative electrode mixture layer weight increase rate)
The weight of the laminate before and after lithium pre-doping was weighed, and the weight increase rate of the negative electrode mixture layer by lithium pre-doping was calculated from the following formula.
Weight increase rate of negative electrode mixture layer by lithium pre-doping =
((Laminated body weight after lithium pre-doping−current collector weight) − (Laminated body weight before lithium pre-doping−Current collector weight)) / (Laminated body weight before lithium pre-doping−Current collector weight) * 100

(Negative electrode layer thickness increase rate)
The laminate thickness before and after lithium pre-doping was measured, and the rate of increase in thickness of the negative electrode mixture layer by lithium pre-doping was calculated from the following formula.
Thickness increase rate of negative electrode mixture layer by lithium pre-doping =
((Laminated body thickness after lithium pre-doping-current collector thickness)-(Laminated body thickness before lithium pre-doping-current collector thickness)) / (Laminated body thickness before lithium pre-doping-current collector thickness) * 100

[Example 1]
<Preparation of carboxylate-containing polymer (C2)>
25% aqueous solution of polyacrylic acid (manufactured by Wako Pure Chemical Industries, Ltd., molecular weight of about 150,000) 29.5 parts by mass (solid content 0.1 mol), 92.2 parts by mass of 1 mol / L lithium hydroxide aqueous solution (solid Was added dropwise with stirring to obtain a lithium polyacrylate aqueous solution having a neutralization degree of 90%. The solid content concentration of this aqueous solution was 7.1%.

<Production of negative electrode>
(Preparation process of negative electrode mixture layer)
12.2 parts by mass of sodium polyacrylate aqueous solution having a neutralization degree of 90% prepared by the above method (solid part 1 part by mass) and 0.6 parts by mass of conductive assistant acetylene black (manufactured by Denki Kagaku Kogyo, HS-100) ) Was kneaded using a battery compound stirrer (Primix Co., Ltd., TK Hibismix Model 2P-03). To the obtained paste, a total of 18.4 parts by mass of silicon oxide (manufactured by Shin-Etsu Chemical Co., KSC-1064) and carbon particles (graphite: manufactured by Hitachi Chemical Co., Ltd., MAGD-20) is added, and H ₂ O is added. Further kneading was performed to prepare a negative electrode mixture paste. The volume ratio of silicon oxide as an active material and carbon particles was 20:80.

This negative electrode mixture paste was applied to a Cu foil (thickness: 18 μm) as a current collector using an applicator, and cured by heat treatment at 150 ° C. for 5 minutes in a nitrogen atmosphere. Thereby, the laminated body by which the electrical power collector and the negative electrode compound-material layer were laminated | stacked was obtained. The mass of the active material in the negative electrode mixture layer after drying was 4 mg / cm ² per unit area.

(Lithium pre-doping process to the negative electrode mixture layer)
<< Preparation of dope solution >>
Under an argon atmosphere, 1.5 parts by mass of BP and 0.15 parts by mass of metallic lithium (manufactured by Honjo Metal) are added to 17.7 parts by mass of THF (made by Wako Pure Chemical Industries, Ltd., deoxygenated grade). The mixture was stirred for 20 minutes at a temperature to prepare a lithium dope solution.

The lithium ion concentration of the lithium dope solution was 0.55 mol / L, and the ratio of the lithium ion concentration to the biphenyl concentration was 110 mol%. Moreover, about the obtained lithium dope solution, ⁷ Li-NMR measurement was performed at 25 degreeC. In the obtained spectrum, the difference in chemical shift value between the main peak (peak A) existing in the range of 3 ppm to 8 ppm and the minor peak (peak B) existing in the range of 1 ppm to 5 ppm (A) (A -B) was 2.7 ppm.

《Pre-Dope》
The laminate produced by the above method was immersed in the dope solution at 25 ° C. for 15 minutes, and lithium was pre-doped into the negative electrode mixture layer of this laminate. After lifting the laminate from the dope solution, the laminate was immersed in THF for 1 minute in order to remove the dope solution adhering to the laminate. Then, the said laminated body was vacuum-dried at 25 degreeC for 5 minute (s), and the negative electrode with which the electrical power collector and the pre-doped negative mix layer were laminated | stacked was obtained.

<Production of coin cell>
A coin cell was prepared using the obtained negative electrode, and the initial charge / discharge efficiency was calculated by the method described above. The results are shown in Table 1.

[Examples 2-4, Comparative Examples 1-3]
<Production of negative electrode>
(Preparation process of negative electrode mixture layer)
The laminate having the negative electrode mixture layer was produced in the same manner as in Example 1.

(Lithium pre-doping process to the negative electrode mixture layer)
<< Preparation of dope solution >>
In the preparation of the dope solution of Example 1, the stirring time of the solution containing THF (made by Wako Pure Chemical Industries, Ltd., deoxygenated grade), BP, and metallic lithium (made by Honjo Metal) is shown in Table 1 or 2. A dope solution was prepared in the same manner except that the changes were made. The ratio of the lithium ion concentration of the obtained dope solution and the chemical shift value difference (AB) obtained by ⁷ Li-NMR measurement were measured in the same manner as in Example 1.

《Predope》
Lithium pre-doping of the obtained negative electrode mixture layer was performed in the same manner as in Example 1 to obtain a negative electrode.

<Production of coin cell>
A coin cell was prepared using the obtained negative electrode, and the initial charge / discharge efficiency was calculated by the method described above. The results are shown in Table 1 or 2.

[Example 5, Comparative Example 4]
<Production of negative electrode>
(Preparation process of negative electrode mixture layer)
A negative electrode mixture paste was prepared in the same manner as in Example 1 except that the volume ratio of silicon oxide and carbon particles was changed as shown in Table 1 or 2, and the current collector and the negative electrode mixture layer were laminated. A laminated body was obtained.

(Lithium pre-doping process to the negative electrode mixture layer)
Lithium pre-doping of the negative electrode mixture layer was performed under the same dope solution and the same pre-dope conditions as in Example 2 to obtain a negative electrode.

<Production of coin cell>
A coin cell was prepared using the obtained negative electrode, and the initial charge / discharge efficiency was calculated by the method described above. The results are shown in Table 1 or 2.

[Examples 6-7, Comparative Examples 5-6]
<Production of negative electrode>
(Preparation process of negative electrode mixture layer)
The same method as in Example 1 except that the addition amount of the polyacrylic acid lithium aqueous solution (carboxylate-containing polymer (C2)) having a neutralization degree of 90% prepared by the above method was changed as shown in Table 1 or 2. A negative electrode mixture paste was prepared to obtain a laminate in which a current collector and a negative electrode mixture layer were laminated.

(Lithium pre-doping process to the negative electrode mixture layer)
Lithium pre-doping of the negative electrode mixture layer was performed under the same dope solution and the same pre-dope conditions as in Example 2 to obtain a negative electrode.

<Production of coin cell>
A coin cell was prepared using the obtained negative electrode, and the initial charge / discharge efficiency was calculated by the method described above. The results are shown in Table 1 or 2.

[Examples 8 to 9]
<Production of negative electrode>
(Preparation process of negative electrode mixture layer)
The laminate having the negative electrode mixture layer was produced in the same manner as in Example 1.

(Lithium pre-doping process to the negative electrode mixture layer)
<< Preparation of dope solution >>
A dope solution was prepared in the same manner as in the preparation of the dope solution of Example 1, except that the concentration of BP in the dope solution was changed as shown in Table 1. The ratio of the lithium ion concentration of the obtained dope solution and the chemical shift value difference (AB) obtained by ⁷ Li-NMR measurement were measured in the same manner as in Example 1.

《Predope》
Lithium pre-doping of the obtained negative electrode mixture layer was performed in the same manner as in Example 1 to obtain a negative electrode.

<Production of coin cell>
A coin cell was prepared using the obtained negative electrode, and the initial charge / discharge efficiency was calculated by the method described above. The results are shown in Table 1.

[Comparative Example 7]
<Production of negative electrode>
(Preparation process of negative electrode mixture layer)
The laminate having the negative electrode mixture layer was produced in the same manner as in Example 7.

(Lithium pre-doping process to the negative electrode mixture layer)
<< Preparation of dope solution >>
Under an argon atmosphere, 0.5 parts by mass of NAP and 0.07 parts by mass of metallic lithium (manufactured by Honjo Metal) are added to 17.7 parts by mass of THF (manufactured by Wako Pure Chemical Industries, Ltd., deoxygenated grade). Stir at 80 ° C. for 80 minutes to prepare a lithium dope solution.

The lithium ion concentration of the dope solution was 0.38 mol / L, and the ratio of the lithium ion concentration to the biphenyl concentration was 190 mol%. Moreover, about the obtained dope solution, ⁷ Li-NMR measurement was performed at 25 degreeC. In the obtained spectrum, the difference in chemical shift value between the main peak (peak A) existing in the range of 3 ppm to 8 ppm and the minor peak (peak B) existing in the range of 1 ppm to 5 ppm (A) (A -B) was 0.3 ppm.

《Pre-Dope》
Lithium pre-doping into the obtained negative electrode mixture layer was performed in the same manner as in Example 4 to obtain a negative electrode.

<Production of coin cell>
A coin cell was prepared using the obtained negative electrode, and the initial charge / discharge efficiency and the weight increase rate and thickness increase rate of the negative electrode mixture layer were calculated by the above-described methods. The results are shown in Table 3.

  As shown in Table 1, a negative electrode mixture layer containing an alloy-based material (A), carbon particles (B), and a binder (C), the alloy-based material (A) and the carbon particles (B) The proportion of the alloy-based material (A) with respect to the total of 10% by volume to 60% by volume and the amount of the binder (C) is 4% by mass to 13% by mass with respect to the total mass of the negative electrode mixture layer The negative electrode mixture layer in the range of 100 to 100 mol% with respect to the concentration of the linear polyphenylene compound (D) containing the linear polyphenylene compound (D) and lithium ions and having a lithium ion concentration. It can be seen that the negative electrodes of Examples 1 to 9 obtained by pre-doping with a certain solution have high initial charge / discharge efficiency.

  On the other hand, as shown in Table 2, the negative electrode mixture layer was formed of a solution having a lithium ion concentration of less than 110 mol% or 150 mol% or more with respect to the concentration of the linear polyphenylene compound (D). It can be seen that the negative electrodes of Comparative Examples 1 to 3 obtained by pre-doping have low initial charge / discharge efficiency.

  The electrode of Comparative Example 4 in which the ratio of the alloy material (A) to the total of the alloy material (A) and the carbon particles (B) in the negative electrode mixture layer is 60% by volume or more is pre-doped with the dope solution of the present application. Even so, it can be seen that the initial charge / discharge efficiency is low.

  Further, the electrodes of Comparative Examples 5 to 6 in which the amount of the binder (C) in the negative electrode mixture layer is less than 4% by mass or more than 13% by mass with respect to the total mass of the negative electrode mixture layer is the dope solution of the present application. It can be seen that the initial charge and discharge efficiency is low even when pre-doping.

  Further, as shown in Table 3, the negative electrode composite material layer was obtained by pre-doping with a solution containing naphthalene and lithium ions and having a lithium ion concentration of 150 mol% or more with respect to the naphthalene concentration. As for the negative electrode of the comparative example 7, it turns out that the weight and volume of the negative electrode increased by pre dope. On the other hand, the negative electrode of Example 4 shows that the weight and volume of a negative electrode increase little by pre dope.

  The nonaqueous electrolyte secondary battery of the present invention has high initial charge / discharge efficiency and high energy density. Therefore, the non-aqueous electrolyte secondary battery can be applied to various uses.

Claims (16)

A method for producing a negative electrode for a nonaqueous electrolyte secondary battery having a negative electrode mixture layer containing a pre-doped alkali metal or alkaline earth metal,
An alloy-based material (A) containing silicon or tin capable of occluding an alkali metal or alkaline earth metal, a negative electrode composite layer containing carbon particles (B) and a binder (C), and included in the negative electrode composite layer The volume of the alloy material (A) is 10% by volume or more and less than 60% by volume when the total volume of the alloy material (A) and the carbon particles (B) is 100% by volume. A step of obtaining a negative electrode mixture layer in which the amount of (C) is 4% by mass to 13% by mass with respect to 100% by mass of the negative electrode mixture layer;
The negative electrode composite material containing the pre-doped alkali metal or alkaline earth metal by bringing the negative electrode composite material layer into contact with a dope solution containing the linear polyphenylene compound (D) and alkali metal ions or alkaline earth metal ions. Obtaining a layer;
Including
The dope solution contains the alkali metal ion or alkaline earth metal ion in an amount of 100 mol% or more and less than 150 mol% with respect to 100 mol% of the total number of moles of the linear polyphenylene compound (D). A method for producing a negative electrode for a battery. In the spectrum obtained by ⁷ Li-NMR measurement of the dope solution at 20 ° C. or more and 30 ° C. or less, the main peak existing in the range of 3 ppm or more and 8 ppm or less in chemical shift is peak A, and the chemical shift value is 1 ppm or more and 5 ppm. When the minor peak existing in the following range is defined as peak B, the chemical shift value difference (AB) between peak A and peak B is more than 1.5 and less than 3, wherein A method for producing a negative electrode for a water electrolyte secondary battery.   The method for producing a negative electrode for a nonaqueous electrolyte secondary battery according to claim 1 or 2, wherein the linear polyphenylene compound (D) is biphenyl, terphenyl or a derivative thereof.   The said dope solution is obtained by stirring for 2 hours or less, after throwing the said alkali metal or the said alkaline-earth metal into the solvent in which the said linear polyphenylene compound (D) was dissolved. A method for producing a negative electrode for a nonaqueous electrolyte secondary battery according to claim 1.   The method for producing a negative electrode for a nonaqueous electrolyte secondary battery according to claim 4, wherein the solvent is tetrahydrofuran.   The nonaqueous electrolyte secondary battery according to any one of claims 1 to 5, wherein the concentration of the linear polyphenylene compound (D) in the dope solution is 0.1 mol / L or more and 4.0 mol / L or less. Manufacturing method for negative electrode. The non-aqueous electrolyte secondary according to claim 1, wherein the alloy material (A) is a silicon oxide represented by SiO _x (0.5 ≦ x ≦ 1.5). A method for producing a negative electrode for a battery. At least a part of the silicon oxide is coated with a carbon material,
The non-aqueous electrolyte secondary battery according to claim 7, wherein a mass of the carbon material to be coated is 2% by mass or more and 50% by mass or less with respect to a total mass of the silicon oxide included in the negative electrode mixture layer. Manufacturing method for negative electrode.   The said carbon particle (B) of the negative electrode for nonaqueous electrolyte secondary batteries as described in any one of Claims 1-8 containing at least 1 type chosen from the group which consists of natural graphite, artificial graphite, and carbon covering graphite. Production method.   The said binder (C) is a manufacturing method of the negative electrode for nonaqueous electrolyte secondary batteries as described in any one of Claims 1-9 containing an imide bond containing polymer (C1) or a carboxylate salt containing polymer (C2). . A step of obtaining a negative electrode by the production method according to claim 1;
Obtaining a non-aqueous electrolyte secondary battery comprising the negative electrode, the positive electrode, and an electrolyte;
Including
A non-aqueous electrolyte in which the total molar amount of alkali metal and alkaline earth metal contained in the negative electrode at full charge is larger than the molar amount of alkali metal and alkaline earth metal calculated from the capacity of the positive electrode active material of the positive electrode A method for manufacturing a secondary battery. A method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery comprising a pre-doped alkali metal or alkaline earth metal,
A negative electrode active material made of an alloy material (A) containing silicon or tin capable of occluding an alkali metal or an alkaline earth metal is doped with a linear polyphenylene compound (D) and an alkali metal ion or an alkaline earth metal ion Contacting with a solution to obtain a negative electrode active material comprising the pre-doped alkali metal or alkaline earth metal,
The dope solution contains the alkali metal ion or alkaline earth metal ion in an amount of 100 mol% or more and less than 150 mol% with respect to 100 mol% of the total number of moles of the linear polyphenylene compound (D). A method for producing a negative electrode active material for a battery. In the spectrum obtained by ⁷ Li-NMR measurement of the dope solution at 20 ° C. or more and 30 ° C. or less, the main peak existing in the range of 3 ppm or more and 8 ppm or less in chemical shift is peak A, and the chemical shift value is 1 ppm or more and 5 ppm. The non-limiting according to claim 12, wherein a difference (A-B) in chemical shift value between the peak A and the peak B is more than 1.5 and less than 3 when a minor peak existing in the following range is defined as the peak B. A method for producing a negative electrode active material for a water electrolyte secondary battery.   The method for producing a negative electrode active material for a nonaqueous electrolyte secondary battery according to claim 12 or 13, wherein the linear polyphenylene compound (D) is biphenyl, terphenyl or a derivative thereof. The non-aqueous electrolyte according to claim 12, wherein the alloy-based material containing silicon or tin is a silicon oxide represented by SiO _x (0.5 ≦ x ≦ 1.5). A method for producing a negative electrode active material for a secondary battery.   The method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery according to claim 15, wherein at least a part of the silicon oxide is coated with a carbon material.