JP5561774B2 - Method for producing non-aqueous electrolyte secondary battery - Google Patents

Description

  Embodiments according to the present invention relate to a method for manufacturing a non-aqueous electrolyte secondary battery.

  With the rapid market expansion of notebook PCs, mobile phones, electric cars, etc., secondary batteries with high energy density are required. As secondary batteries, development of non-aqueous electrolyte secondary batteries and lithium ion secondary batteries is in progress. Examples of means for obtaining a high energy density non-aqueous electrolyte secondary battery include a method using a negative electrode material having a large capacity, a method using a non-aqueous electrolyte excellent in stability, and the like.

  Patent Document 1 discloses that silicon oxide or silicate is used as a negative electrode active material of a secondary battery. Patent Document 2 discloses a negative electrode for a secondary battery including an active material layer including carbon material particles capable of occluding and releasing lithium ions, metal particles capable of being alloyed with lithium, and oxide particles capable of occluding and releasing lithium ions. Is disclosed. Patent Document 3 discloses a negative electrode material for a secondary battery in which the surface of particles having a structure in which silicon microcrystals are dispersed in a silicon compound is coated with carbon.

  Patent Document 4 and Patent Document 5 describe using polyimide as a binder for a negative electrode when the negative electrode active material contains silicon.

  Patent Document 6 discloses a method for manufacturing a lithium ion secondary battery in which an electrolytic solution is injected and the charging step is performed at least once before the injection port sealing step. Patent Document 7 discloses a method for manufacturing a lithium ion secondary battery in which after injection, the battery is charged, left standing, discharged, and injected for the second time.

JP-A-6-325765 JP 2003-123740 A JP 2004-47404 A Japanese Patent Laid-Open No. 2004-22433 JP 2007-95670 A JP 2006-260864 A JP 2009-199756 A

  However, when a secondary battery using a silicon oxide described in Patent Document 1 as a negative electrode active material is charged / discharged at 45 ° C. or higher, there is a problem that the capacity drop accompanying the charge / discharge cycle is remarkably large. . The negative electrode for a secondary battery described in Patent Document 2 has an effect of relaxing the volume change of the negative electrode as a whole when occluding and releasing lithium due to differences in charge / discharge potentials and expansion / contraction rates of the three components. However, a detailed description of the manufacturing method of the nonaqueous electrolyte secondary battery and the binder, electrolyte solution, electrode element structure, and exterior body that are indispensable for forming the nonaqueous electrolyte secondary battery are sufficient. Many points have not been examined. The negative electrode material for secondary batteries described in Patent Document 3 also has an effect of reducing volume change as a whole of the negative electrode. However, a detailed description on a method for manufacturing a nonaqueous electrolyte secondary battery and a nonaqueous electrolyte secondary battery In many cases, the binder, the electrolyte solution, the electrode element structure, and the outer package, which are indispensable for forming a battery, have not been sufficiently studied.

  In Patent Document 4 and Patent Document 5, in addition to insufficient studies regarding the state of the negative electrode active material, a detailed description of a method for manufacturing a non-aqueous electrolyte secondary battery and a non-aqueous electrolyte secondary battery are formed. In many cases, the electrolyte solution, the electrode element structure, and the exterior body, which are indispensable for doing so, have not been sufficiently studied.

  In Patent Document 6, the sealing process is delayed in order to avoid blistering due to gas generation, but the amount of the electrolytic solution in accordance with the electrode active material has not been optimized. Further, in Patent Document 7, a certain effect was obtained in a system using some negative electrode active materials, but in a system using a specific negative electrode active material, an electrolytic solution to be injected in the second liquid injection step. The desired effect was not obtained because the amount was too small.

  Accordingly, an object of the embodiment according to the present invention is to provide a non-aqueous electrolyte secondary battery capable of long-life driving.

An embodiment according to the present invention includes an electrode element in which a positive electrode and a negative electrode are arranged to face each other, a non-aqueous electrolyte, and an outer package that contains the electrode element and the non-aqueous electrolyte. The proportion of the negative electrode active material having a binder and a plurality of types of negative electrode active materials having different volume change rates due to charge and discharge and having the largest volume change rate is more than 5 parts by mass and less than 95 parts by mass of the whole negative electrode active material. A method for producing a non-aqueous electrolyte secondary battery, comprising:
A first step of injecting the non-aqueous electrolyte into the exterior body containing the electrode element;
A second step of charging the cell obtained in the first step at least once;
A third step in which 5 hours or more have elapsed from the start time of the second step;
A fourth step of injecting the non-aqueous electrolyte having a mass of 0.5 to 2.0 times the A value defined below into the exterior body of the cell that has undergone the third step. This is a method for producing a non-aqueous electrolyte secondary battery.
A (g) = nonaqueous electrolyte density (g / ml) × [(cell volume at the start of the third step (ml)) − (cell volume at the end of the first step (ml))]

  According to the embodiment of the present invention, it is possible to provide a non-aqueous electrolyte secondary battery capable of long-life driving.

FIG. 3 is a schematic cross-sectional view showing a structure of an electrode element included in a laminated laminate type secondary battery.

  Hereinafter, this embodiment will be described in detail.

  In the non-aqueous electrolyte secondary battery according to this embodiment, an electrode element in which a positive electrode and a negative electrode are arranged to face each other and a non-aqueous electrolyte are included in an exterior body. The shape of the non-aqueous electrolyte secondary battery may be any of a cylindrical type, a flat wound square type, a laminated square type, a coin type, a flat wound laminated type, and a laminated laminate type, and a laminated laminate type is preferable. Hereinafter, a laminated laminate type nonaqueous electrolyte secondary battery will be described.

  FIG. 1 is a schematic cross-sectional view showing a structure of an electrode element included in a laminated laminate type nonaqueous electrolyte secondary battery. This electrode element is formed by alternately stacking a plurality of positive electrodes c and a plurality of negative electrodes a with a separator b interposed therebetween. The positive electrode current collector e of each positive electrode c is welded to and electrically connected to each other at an end portion not covered with the positive electrode active material, and a positive electrode terminal f is welded to the welded portion. The negative electrode current collector d of each negative electrode a is welded and electrically connected to each other at an end portion not covered with the negative electrode active material, and a negative electrode terminal g is welded to the welded portion. Note that the positive electrode terminal f and the negative electrode terminal g may be located on the same side of the four sides of the multilayer body as long as they are not short-circuited.

  Since the electrode element having such a planar laminated structure does not have a portion with a small R (a region close to the winding core of the wound structure or a region corresponding to the folded portion), it has a comparison with an electrode element having a wound structure. There is an advantage that it is difficult to be adversely affected by the volume change of the electrode accompanying charging and discharging. That is, it is effective as an electrode element using an active material that easily causes volume expansion. On the other hand, in an electrode element having a wound structure, since the electrode is curved, the structure is easily distorted when a volume change occurs. In particular, when a negative electrode active material having a large volume change due to charging / discharging such as silicon or silicon oxide is used, in a non-aqueous electrolyte secondary battery using an electrode element having a wound structure, the capacity accompanying charging / discharging The decline is often significant.

  However, the electrode element having a planar laminated structure has a problem that when the gas is generated between the electrodes, the generated gas tends to stay between the electrodes. This is because, in the case of an electrode element having a wound structure, the distance between the electrodes is difficult to widen because tension is applied to the electrodes, whereas in the case of an electrode element having a laminated structure, the distance between the electrodes is widened. This is because it is easy. This problem is particularly noticeable when the outer package is an aluminum laminate film.

  In addition, when the exterior body is an aluminum laminate film, if too much non-aqueous electrolyte is added, the overflowing non-aqueous electrolyte will adhere to the sealing part and melt the insulating resin on the surface of the aluminum laminate during sealing. A short circuit between internal aluminum materials may be caused. This short circuit alone does not directly lead to a short circuit of the battery, but if the electrode element contacts the aluminum material inside the aluminum laminate due to wear or scratches, it should be avoided. It is a phenomenon. Therefore, care should be taken not to overflow the non-aqueous electrolyte, but depending on the specifications, the amount of non-aqueous electrolyte required increases, so inject sufficient non-aqueous electrolyte in one injection process. Was difficult.

  In the present embodiment, when a negative electrode active material having a large change in volume expansion associated with charge / discharge is used, a sufficient non-aqueous electrolyte can be injected by a plurality of liquid injection processes involving charge / discharge. I found out. In other words, paying attention to the above-mentioned problems and solutions, long-life driving is possible even in laminated non-aqueous electrolyte secondary batteries using negative electrode active materials that have large changes in volume expansion due to charge and discharge. I found out that

  Hereinafter, details of the non-aqueous electrolyte secondary battery and the manufacturing method thereof will be described.

[1] Negative electrode The negative electrode is formed by binding a negative electrode active material so as to cover a negative electrode current collector with a negative electrode binder. In this embodiment, as the negative electrode active material, the proportion of the negative electrode active material having two or more types of active materials having different volume change rates due to charge and discharge and having the largest volume change rate is more than 5 parts by mass. Less than part by mass. It is preferable to use silicon capable of forming an alloy with lithium as the negative electrode active material.

  Furthermore, a negative electrode active material comprising a carbon material (a) capable of occluding and releasing lithium, a metal (b) capable of forming an alloy with lithium, and a metal oxide (c) capable of occluding and releasing lithium is used. It is preferable. The proportion of the carbon material (a) is preferably 2% by mass or more and 50% by mass or less, and preferably 2% by mass or more and 30% by mass or less with respect to the total of the carbon material (a), the metal (b) and the metal oxide (c). It is preferable to set it as mass% or less. In general, metal (b) has a larger volume change rate due to charge and discharge than other components, and the ratio of metal (b) in this case is the carbon material (a), metal (b) and metal oxide ( Although it is more than 5 mass% and less than 95 mass% with respect to the sum total of c), it is preferable to set it as 10 to 85 mass%. The ratio of the metal oxide (c) is preferably 5% by mass or more and 90% by mass or less with respect to the total of the carbon material (a), the metal (b) and the metal oxide (c). It is preferable to set it to 70 mass% or less.

  As the carbon material (a), graphite, amorphous carbon, diamond-like carbon, carbon nanotube, or a composite thereof can be used. Here, graphite with high crystallinity has high electrical conductivity, and is excellent in adhesiveness and voltage flatness with a positive electrode current collector made of a metal such as copper. Therefore, it is advantageous in designing a high output / high energy secondary battery. On the other hand, since amorphous carbon having low crystallinity has a relatively small volume expansion, it has a high effect of relaxing the volume expansion of the entire negative electrode, and deterioration due to non-uniformity such as crystal grain boundaries and defects hardly occurs. Therefore, it is advantageous in designing a long-life / high-robustness secondary battery.

  As the metal (b), Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, La, or an alloy of two or more of these can be used. . In particular, silicon (Si) is preferably included as the metal (b).

  As the metal oxide (c), silicon oxide, tin oxide, aluminum oxide, indium oxide, zinc oxide, lithium oxide, or a composite thereof can be used. In particular, the metal oxide (c) preferably includes an oxide of a metal constituting the metal (b), and more preferably includes silicon oxide. This is because silicon oxide is relatively stable and hardly causes a reaction with other compounds. Moreover, 0.1-5 mass% of 1 type, or 2 or more types of elements chosen from nitrogen, boron, and sulfur can also be added to a metal oxide (c). By carrying out like this, the electrical conductivity of a metal oxide (c) can be improved.

  All or part of the metal oxide (c) preferably has an amorphous structure. The amorphous metal oxide (c) can suppress the volume expansion of the carbon material (a) and the metal (b), which are other negative electrode active materials, and can also suppress the decomposition of the non-aqueous electrolyte. . Although this mechanism is not clear, it is presumed that the formation of a film on the interface between the carbon material (a) and the non-aqueous electrolyte has some influence due to the amorphous structure of the metal oxide (c). The amorphous structure is considered to have relatively few elements due to non-uniformity such as crystal grain boundaries and defects. In addition, it can be confirmed by X-ray diffraction measurement (general XRD measurement) that all or part of the metal oxide (c) has an amorphous structure. Specifically, when the metal oxide (c) does not have an amorphous structure, a peak specific to the metal oxide (c) is observed, but all or part of the metal oxide (c) is amorphous. When it has a structure, the intrinsic peak is observed as a broad in the metal oxide (c).

  Moreover, it is preferable that all or part of the metal (b) is dispersed in the metal oxide (c). By dispersing at least a part of the metal (b) in the metal oxide (c), the volume expansion of the whole negative electrode can be further suppressed, and the decomposition of the non-aqueous electrolyte can also be suppressed. Note that all or part of the metal (b) is dispersed in the metal oxide (c) because it is observed with a transmission electron microscope (general TEM observation) and energy dispersive X-ray spectroscopy (general). This can be confirmed by using a combination of a standard EDX measurement. Specifically, the cross section of the sample containing the metal particles (b) is observed, the oxygen concentration of the metal particles (b) dispersed in the metal oxide (c) is measured, and the metal particles (b) are configured. It can be confirmed that the metal being used is not an oxide.

  In such a composite of the carbon material (a), the metal (b), and the metal oxide (c), all or part of the metal oxide (c) has an amorphous structure, and all or part of the metal (b) A negative electrode active material in which a part is dispersed in the metal oxide (c) can be produced by a method disclosed in Patent Document 3, for example. That is, by performing a CVD process on the metal oxide (c) in an atmosphere containing an organic gas such as methane gas, the metal (b) in the metal oxide (c) is nanoclustered and the surface is a carbon material (a ) Can be obtained. This composite can be used as a negative electrode active material.

  As the binder for the negative electrode, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polytetrafluoroethylene, polypropylene, polyethylene, Polyimide, polyamideimide, or the like can be used. Of these, polyimide or polyamideimide is preferred because of its high binding properties. The content of the negative electrode binder in the negative electrode is 5 to 25 parts by mass with respect to 100 parts by mass of the negative electrode active material from the viewpoints of “sufficient binding force” and “higher energy” that are in a trade-off relationship. preferable.

  As the negative electrode current collector, copper, nickel, silver, and alloys thereof are preferable in view of electrochemical stability. Examples of the shape include foil, flat plate, and mesh.

  A negative electrode active material layer containing a carbon material (a) as a negative electrode active material and a negative electrode active material layer containing a composite of a carbon material (a), a metal (b) and a metal oxide (c) as a negative electrode active material, It can be formed by a general slurry coating method. That is, the negative electrode current collector can be formed by applying and drying a negative electrode slurry containing the carbon material (a), and compressing and molding the negative electrode slurry. The negative electrode slurry can be obtained by dispersing and kneading the carbon material (a) and other negative electrode active materials together with a negative electrode binder in a solvent such as N-methyl-2-pyrrolidone (NMP). Examples of the method for applying the negative electrode slurry include a doctor blade method and a die coater method. At this time, the negative electrode active material layer is formed such that the negative electrode active material covers the negative electrode current collector with the negative electrode binder.

  In addition to the slurry coating method described above, the negative electrode active material layer made of metal (b) as the negative electrode active material is a melt cooling method, a liquid quenching method, an atomizing method, a vacuum deposition method, a sputtering method, a plasma CVD method, and a photo CVD method. It can be formed by a method such as a method, a thermal CVD method, or a sol-gel method. Further, the negative electrode active material layer made of the metal oxide (c) as the negative electrode active material can be formed by a method such as a vapor deposition method, a CVD method, or a sputtering method in addition to the slurry coating method described above. Furthermore, after forming a negative electrode active material layer beforehand, a composite negative electrode can also be produced by a method of forming a metal thin film that becomes a negative electrode current collector by a method such as vapor deposition or sputtering.

[2] Positive Electrode The positive electrode is formed, for example, by binding a positive electrode active material so as to cover the positive electrode current collector with a positive electrode binder.

As the positive electrode active material, lithium manganate having a layered structure such as LiMnO ₂ , Li _x Mn ₂ O ₄ (0 <x <2) or lithium manganate having a spinel structure; LiCoO ₂ , LiNiO ₂ or a transition metal thereof Lithium transition metal oxides in which a specific transition metal such as LiNi _1/3 Co _1/3 Mn _1/3 O ₂ does not exceed half; Lithium transition metal oxides In which Li is made excessive in comparison with the stoichiometric composition. In particular, Li _α Ni _β Co _γ Al _δ O ₂ (1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.7, γ ≦ 0.2), Li _α Ni _β Co _γ Mn _δ O ₂ (1 ≦ α ≦ 1.2, β + γ + δ = 1, β ≧ 0.6, γ ≦ 0.2) or Li _α Ni _β Co _γ Mn _δ Al _ε Mg _ζ O ₂ (1 ≦ α ≦ 1.2, β + γ + δ + ε + ζ = 1, β ≧ 0.5, 0 ≦ γ ≦ 0.2, 0.01 ≦ δ ≦ 0.49, 0 ≦ γ ≦ 0.3, and 0 ≦ γ ≦ 0.1) are preferable. A positive electrode active material can be used individually by 1 type or in combination of 2 or more types.

  As the positive electrode binder, the same binder as the negative electrode binder can be used. Among these, polyvinylidene fluoride is preferable from the viewpoint of versatility and low cost. The amount of the binder for the positive electrode to be used is preferably 2 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material from the viewpoints of “sufficient binding force” and “high energy” which are in a trade-off relationship. .

  As the positive electrode current collector, aluminum, nickel, silver, SUS, valve metal, and alloys thereof can be used from the viewpoint of electrochemical stability, and aluminum is particularly preferable.

  A conductive auxiliary material may be added to the positive electrode active material layer containing the positive electrode active material for the purpose of reducing impedance. Examples of the conductive auxiliary material include carbonaceous fine particles such as graphite, carbon black, and acetylene black.

[3] Non-aqueous electrolyte As the non-aqueous electrolyte, a solution obtained by dissolving a supporting salt in a non-aqueous solvent is used.

  Nonaqueous solvents are commonly used as solvents for nonaqueous electrolytes. For example, carbonates, chlorinated hydrocarbons, ethers, ketones, esters, nitriles, and the like can be used. A non-aqueous solvent can be used individually by 1 type or in combination of 2 or more types. Among these, as the non-aqueous solvent, at least one of high-dielectric constant non-aqueous solvents such as ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and those substituted with fluorine, and diethyl carbonate (DEC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), esters other than γ-butyrolactone (particularly phosphate esters), ethers, and non-aqueous low dielectric constants such as those substituted with fluorine It is preferable to use a mixed liquid in which at least one solvent is mixed, (EC or PC, or EC + PC) + (one, two or three mixed liquids selected from the group consisting of DEC, EMC, and DMC, or Also mixed with fluorinated ethers or phosphate esters Of) is preferred.

As the fluorinated ether, the following formula (1):
^{H- (CX 1 X 2 -CX 3} X 4) n -CH 2 O-CX 5 X 6 -CX 7 X 8 -H (1)
Wherein (1), n is 1, 2, 3 or 4, X ¹ ~X ⁸ are each independently a fluorine atom or a hydrogen atom. However, at least one of X ^{1 to} X ⁴ is a fluorine atom, and at least one of X ^{5 to} X ⁸ is a fluorine atom. Further, the atomic ratio of fluorine atoms to hydrogen atoms bonded to the compound of formula (1) [(total number of fluorine atoms) / (total number of hydrogen atoms)] ≧ 1. ]
A compound represented by the following formula (2):
_{H- (CF 2 -CF 2) n} -CH 2 O-CF 2 -CF 2 -H (2)
[In Formula (2), n is 1 or 2. ]
Is more preferable. A fluorinated ether can be used individually by 1 type or in combination of 2 or more types.

  As phosphoric acid esters, triethyl phosphate and tris (2,2,2-trifluoroethyl) phosphate can be used.

Examples of the supporting salt include LiPF ₆ , LiAsF ₆ , LiAlCl ₄ , LiClO ₄ , LiBF ₄ , LiSbF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) Lithium salt such as ₂ can be used. The supporting salt can be used alone or in combination of two or more.

[4] Separator As the separator, a porous film such as polypropylene or polyethylene or a nonwoven fabric can be used. Moreover, what laminated | stacked them can also be used as a separator.

[5] Electrode element structure Examples of the electrode element structure include a cylindrical wound structure, a flat wound structure, a zigzag folded structure, and a laminated structure. A laminated structure is particularly preferable. Since the electrode element having a planar laminated structure does not have a portion with a small R (region close to the winding core of the wound structure or region corresponding to the folded portion), when an active material having a large volume change due to charge / discharge is used, Compared to an electrode element having a wound structure, there is an advantage that it is less likely to be adversely affected by the volume change of the electrode accompanying charge / discharge.

[6] Exterior Body The exterior body can be appropriately selected as long as it is stable to the non-aqueous electrolyte and has a sufficient water vapor barrier property. For example, a can made of aluminum as a main material, a can made of iron or stainless steel, a laminate resin, or the like can be used. In particular, a laminate resin is preferable. As the exterior body in the case of a non-aqueous electrolyte secondary battery using a laminate resin as the exterior body, a laminate film such as aluminum or silica-coated polypropylene or polyethylene can be used. In particular, an aluminum laminate film is preferably used from the viewpoints of versatility and cost.

  In this embodiment, since the non-aqueous electrolyte is injected into a plurality of times, it is particularly preferable to use a laminate film outer package that is easy to open, inject, and reseal. In addition, as a method of opening work, (1) opening a hole, (2) cutting a preliminary | backup part, (3) preparing the liquid injection port after the 2nd time in advance, opening the liquid injection port, etc. The method is mentioned.

[7] Manufacturing Method The manufacturing method of the nonaqueous electrolyte secondary battery according to this embodiment includes four steps. Details thereof will be described below.

  First, a nonaqueous electrolytic solution is injected into an exterior body that encloses an electrode element (first step). In the first step, one type of non-aqueous electrolyte may be injected at a time, a plurality of types of non-aqueous electrolytes may be injected at a time, and one type of non-aqueous electrolyte may be injected. You may inject in multiple times, and you may inject several types of non-aqueous electrolyte in multiple times. When performing the liquid injection work a plurality of times, the interval may be several seconds to several hours.

  Next, the cell obtained in the first step is charged at least once (second step). In the second step, the battery may be charged to a fully charged state at one time, or may be charged to a fully charged state in a plurality of times. The fully charged state is defined by voltage, specifically 4.0 to 4.4V is preferable, and 4.1V to 4.25V is more preferable. The charging method is preferably constant current constant voltage charging. The constant current value at that time is preferably a current value of 1 C or less when a current value that can charge all of the positive electrode active material contained in the secondary battery in 1 hour is a 1 C current value. More preferably, the current value is -0.3C. Further, the time for charging is preferably about 1 to 20 hours, and more preferably about 5 to 12 hours. Although it may discharge after charge, it is preferable to charge again after discharge.

  Next, 5 hours or more have elapsed from the start time of the second step (third step). Specifically, the cell that has undergone the second step may be left for a predetermined time. The cell at this time may be in a charged state or a discharged state, but is preferably left in a fully charged state, and more preferably left in a state where no current for charging flows in the fully charged state. The time elapsed from the start time of the second step may be 5 hours or more, preferably 24 to 504 hours, and more preferably 168 to 336 hours. The ambient temperature when the cell is left is preferably 20 to 60 ° C. If the time of 5 hours or more from the start time of the second step is secured, the target effect can be obtained in a shorter standing time as the environmental temperature at the time of leaving the cell is higher.

  Next, the nonaqueous electrolytic solution is injected again into the outer package of the cell that has undergone the third step (fourth step). In the fourth step, one type of non-aqueous electrolyte may be injected at a time, a plurality of types of non-aqueous electrolytes may be injected at a time, and one type of non-aqueous electrolyte may be injected. You may inject in multiple times, and you may inject several types of non-aqueous electrolyte in multiple times. When performing the liquid injection work a plurality of times, the interval may be several seconds to several hours. The fourth step may be performed immediately after the third step, but may be performed after waiting for the temperature of the battery to reach room temperature depending on the environmental temperature in the third step. The fourth step may be performed after the cell is fully charged, or may be performed after discharging.

However, the amount of the nonaqueous electrolytic solution to be injected in the fourth step is 0.5 to 2.0 times the mass of the A value defined below. More preferably, the mass is 0.8 to 1.2 times. The cell volume can be measured by, for example, the Archimedes method.
A (g) = nonaqueous electrolyte density (g / ml) × [(cell volume at the start of the fourth step (ml)) − (cell volume at the end of the first step (ml))]
When a plurality of types of negative electrode active materials having different volume change rates due to charge and discharge are included and the ratio of the material having the largest volume change rate is more than 5 parts by mass and less than 95 parts by mass, Voids are likely to be generated. Specifically, voids are likely to occur due to misalignment of the particle arrangement in the electrode due to expansion / contraction caused by two types of particles having different volume change rates. Thereafter, in the third step, the non-aqueous electrolyte is sufficiently diffused into the gaps in the electrodes, and the non-aqueous electrolyte is uniformly arranged in the gaps. In the fourth step, the nonaqueous electrolyte secondary battery having a sufficient amount of nonaqueous electrolyte in the exterior body is obtained without overflowing the nonaqueous electrolyte.

  The manufacturing method according to the present embodiment is not limited to a lithium ion secondary battery, but a non-aqueous electrolyte secondary battery such as a sodium ion secondary battery, a magnesium ion secondary battery, an aluminum ion secondary battery, or a calcium ion secondary battery. It can also be applied to secondary batteries.

  Hereinafter, the present embodiment will be specifically described by way of examples.

Example 1
Mass of 32:68 with silicon having an average particle size of 5 μm as metal (b) and amorphous silicon oxide (SiO _x , 0 <x ≦ 2) with an average particle size of 13 μm as metal oxide (c) The negative electrode active material was obtained by measuring by ratio and mixing by so-called mechanical milling for 24 hours. In this negative electrode active material, silicon as the metal (b) is dispersed in silicon oxide (SiO _x , 0 <x ≦ 2) as the metal oxide (c). Silicon has a larger volume change due to charge and discharge than amorphous silicon oxide. The obtained negative electrode active material (average particle size D50 = 5 μm) and PVdF (trade name: KF polymer # 9210, manufactured by Kureha Co., Ltd.) as a negative electrode binder were weighed at a mass ratio of 80:20. These were mixed with n-methylpyrrolidone to obtain a negative electrode slurry. The negative electrode slurry was applied to a copper foil having a thickness of 15 μm so as to have an amount of 2.5 mg per 1 cm ² , dried and pressed, and cut into 170 mm × 88 mm to produce a negative electrode.

A mass ratio of lithium nickelate (LiNi _0.80 Co _0.15 Al _0.15 O ₂ ) as the positive electrode active material, carbon black as the conductive auxiliary material, and polyvinylidene fluoride as the positive electrode binder is 90: 5: 5 And mixed with n-methylpyrrolidone to obtain a positive electrode slurry. The positive electrode slurry was applied to an aluminum foil having a thickness of 20 μm so as to have an amount of 20 mg per 1 cm ² , dried and pressed, and cut into 166 mm × 84 mm to produce a positive electrode.

  The obtained 8 layers of the positive electrode and 9 layers of the negative electrode were alternately stacked while sandwiching a polypropylene porous film as a separator. The ends of the positive electrode current collector that is not covered with the positive electrode active material and the negative electrode current collector that is not covered with the negative electrode active material are welded, and the positive electrode terminal made of aluminum and the negative electrode terminal made of nickel are further welded to the welded portions. Were respectively welded to obtain an electrode element having a planar laminated structure. This electrode element was wrapped with an aluminum laminate film as an outer package, and the two sides where the tabs came out were sealed with a heat sealing machine. One side is not sealed because it is a folded portion of aluminum laminate.

Next, as a first step, 20 g of a nonaqueous electrolytic solution was injected into the exterior body. As the non-aqueous electrolyte, EC / PC / DMC / EMC / DEC / HF ₂ C—CF ₂ —CH ₂ —O—CF ₂ —CF ₂ H = 10/10 containing LiPF ₆ at a concentration of 1 mol / L. A mixed solvent of / 10/10/20/40 (volume ratio) was used. The density of this non-aqueous electrolyte was 1.3 g / ml. Then, the non-aqueous-electrolyte secondary battery was produced by sealing using a vacuum packaging machine (product name: V305GII, made by TOSPAC) while reducing the pressure to 0.1 atm or less.

  Next, as a second step, the battery was charged with constant current and constant voltage (first time). The charging current at this time was set to a 0.1 C current value when a current value capable of charging all of the positive electrode active materials contained in the battery in 1 hour was a 1 C current value, and a charging time was set to 10 hours. Thereafter, the battery was discharged at a 1C current value and recharged to a fully charged state at a 1C current value. The second step was performed at room temperature.

  Next, as the third step, the battery was left until 15 hours (management time) had elapsed from the start time of the second step. The third step was performed in a 60 ° C. environment.

  Next, as a fourth step, the nonaqueous electrolytic solution was injected again into the exterior body. Since the volume change amount of the battery ((cell volume at the start of the fourth step (ml)) − (cell volume at the end of the first step (ml)), the same applies hereinafter) was 5 ml. 6.5 g of the non-aqueous electrolyte solution, which is one time the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte solution, was injected. The volume of the battery was measured by the Archimedes method.

(Example 2)
Except that polyimide (Ube Industries, Ltd., trade name: U Varnish A) was used as the negative electrode binder, the negative electrode slurry was applied and then dried, and further heat treatment was performed at 350 ° C. in a nitrogen atmosphere. 1 was carried out. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Example 3)
Silicon oxide powder (mixture of silicon oxide and silicon) represented by the general formula SiO is subjected to CVD treatment at 1150 ° C. for 6 hours in an atmosphere containing methane gas, so that silicon in silicon oxide is nanoclustered and the surface A silicon-silicon oxide-carbon composite (negative electrode active material) coated with carbon was obtained. Silicon has a larger volume change due to charging and discharging than silicon oxide and carbon. The obtained negative electrode active material (average particle diameter D50 = 5 μm) and polyimide as a negative electrode binder (made by Ube Industries, trade name: U varnish A) were weighed at a mass ratio of 80:20. These were mixed with n-methylpyrrolidone to obtain a negative electrode slurry. The negative electrode slurry was applied to the surface of a copper foil having a thickness of 10 μm so as to have an amount of 2.5 mg per 1 cm ² and then dried. Similarly, the negative electrode slurry was also applied to the back surface and dried, followed by heat treatment at 350 ° C. in a nitrogen atmosphere. Thus, a negative electrode was produced.

  It implemented like Example 1 except having used the negative electrode produced as mentioned above. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Comparative Example 1)
Graphite material (average particle diameter D50 = 20 μm) and polyimide as a binder for negative electrode (Ube Industries, Ltd., trade name: U Varnish A) are weighed at a mass ratio of 80:20, and they are n -It mixed with methylpyrrolidone and it was set as the negative electrode slurry. The negative electrode slurry is applied to a copper foil having a thickness of 15 μm so as to have an amount of 18.0 mg per 1 cm ² , dried and pressed, further heat-treated at 350 ° C. in a nitrogen atmosphere, and then cut into 170 mm × 88 mm. Thus, a negative electrode was produced.

  It implemented like Example 1 except having used the negative electrode produced as mentioned above. Since the volume change amount of the battery was 2.5 ml, in the fourth step, 3.25 g of non-aqueous electrolyte, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte, is used. A water electrolyte was injected.

(Example 4)
The second step was carried out in the same manner as in Example 3 except that only the first charge was performed and the discharge and recharge were not performed. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Example 5)
The first charge in the second step is performed at a current value of 0.5 C, the charging time is 1 hour, and the time for which the battery is left in the third step is the fourth step from the start time of the second step. This was carried out in the same manner as in Example 3 except that the time until the start time was adjusted to 5 hours. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Example 6)
The third step is performed in an environment of 60 ° C., and the time for which the battery is left in the third step is 168 hours from the start time of the second step to the start time of the fourth step. The same procedure as in Example 3 was performed except that the adjustment was made. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Example 7)
In Example 4, except that 3.25 g of the nonaqueous electrolyte solution, which is 0.5 times the value obtained by multiplying the volume change amount of the battery by the density of the nonaqueous electrolyte solution, was injected. It carried out similarly.

(Example 8)
In the fourth step, the same procedure as in Example 3 was performed except that 13 g of the nonaqueous electrolyte solution, which was twice the value obtained by multiplying the volume change amount of the battery by the density of the nonaqueous electrolyte solution, was injected. .

Example 9
The same procedure as in Example 3 was performed except that polyamideimide (manufactured by Toyobo Co., Ltd., trade name: Viromax (registered trademark)) was used as the binder for the negative electrode. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Comparative Example 2)
The first charge in the second step is performed at a current value of 0.5 C, the charging time is 1 hour, and the time for which the battery is left in the third step is the fourth step from the start time of the second step. This was carried out in the same manner as in Example 3 except that the time until the start time was adjusted to 4 hours. However, since the volume change amount of the battery was 5 ml, in the fourth step, 1.625 g of non-aqueous electrolyte was 0.25 times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. A water electrolyte was injected.

(Comparative Example 3)
The third step was carried out in the same manner as in Example 3 except that the battery was left until 15 hours passed from the end time of the first step without performing the second step. However, since the volume change of the battery was 1 ml, in the fourth step, 0.325 g of non-aqueous electrolyte, which is 0.25 times the value obtained by multiplying the volume change of the battery by the density of the nonaqueous electrolyte, is used. A water electrolyte was injected.

(Comparative Example 4)
Without performing the second step, the third step was performed in the same manner as in Example 3 except that the battery was left until 4 hours passed from the end time of the first step. However, since the volume of the battery did not change (0 ml), the nonaqueous electrolyte solution was not injected in the fourth step (injection amount: 0 g).

(Comparative Example 5)
The third step was carried out in the same manner as in Example 3 except that the battery was left until 15 hours passed from the end time of the first step without performing the second step. However, since the volume of the battery did not change (0 ml), the nonaqueous electrolyte solution was not injected in the fourth step (injection amount: 0 g).

(Comparative Example 6)
The first charge in the second step is performed at a current value of 0.5 C, the charging time is 1 hour, and the time for which the battery is left in the third step is the fourth step from the start time of the second step. This was carried out in the same manner as in Example 3 except that the time until the start time was adjusted to 4 hours. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Comparative Example 7)
In Example 4, except that 1.625 g of the non-aqueous electrolyte solution, which was 0.25 times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte solution, was injected. It carried out similarly.

(Comparative Example 8)
In Example 4, except that 16.25 g of the non-aqueous electrolyte, which is 2.5 times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte, was injected. It carried out similarly.

(Example 10)
Silicon having an average particle diameter of 5 μm and amorphous silicon oxide having an average particle diameter of 13 μm (SiO _x , 0 <x ≦ 2) are weighed at a mass ratio of 25:75, and mixed by so-called mechanical milling for 24 hours. It implemented like Example 1 except having obtained the negative electrode active material. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Example 11)
Silicon having an average particle diameter of 5 μm and amorphous silicon oxide (SiO _x , 0 <x ≦ 2) having an average particle diameter of 13 μm are weighed at a mass ratio of 85:15 and mixed by so-called mechanical milling for 24 hours. It implemented like Example 1 except having obtained the negative electrode active material. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Example 12)
A mass of 85:15 of tin having an average particle diameter of 5 μm as the metal (b) and amorphous tin oxide (SnO _x , 0 <x ≦ 2) having an average particle diameter of 13 μm as the metal oxide (c) The measurement was carried out in the same manner as in Example 1 except that the negative electrode active material was obtained by weighing by ratio and mixing by so-called mechanical milling for 24 hours. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured. Tin has a larger volume change due to charging and discharging than amorphous tin oxide.

(Comparative Example 9)
Silicon having an average particle diameter of 5 μm and amorphous silicon oxide (SiO _x , 0 <x ≦ 2) having an average particle diameter of 13 μm are weighed at a mass ratio of 5:95 and mixed by so-called mechanical milling for 24 hours. It implemented like Example 1 except having obtained the negative electrode active material. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Comparative Example 10)
Silicon having an average particle diameter of 5 μm and amorphous silicon oxide having an average particle diameter of 13 μm (SiO _x , 0 <x ≦ 2) are weighed at a mass ratio of 95: 5 and mixed by so-called mechanical milling for 24 hours. It implemented like Example 1 except having obtained the negative electrode active material. Since the volume change amount of the battery was 5 ml, in the fourth step, 6.5 g of non-aqueous electrolysis, which is one times the value obtained by multiplying the volume change amount of the battery by the density of the non-aqueous electrolyte. The liquid was poured.

(Example 13)
The same procedure as in Example 1 was performed except that HF ₂ C—CF ₂ —CH ₂ —O—CF ₂ —CF ₂ H was changed to triethyl phosphate (PO (OCH ₂ CH ₃ ) ₃ ).

<Evaluation>
The produced non-aqueous electrolyte secondary battery is subjected to a cycle test in which charging and discharging are repeated in a voltage range of 2.5 V to 4.1 V in a thermostat kept at 60 ° C., and the capacity maintenance ratio and the volume change are evaluated. did. The test results are shown in Table 1. In Table 1, “60 ° C. 50 cycle maintenance ratio” represents (discharge capacity at the 50th cycle) / (discharge capacity at the first cycle) (unit:%). Further, “60 ° C., 50 cycle volume change” represents (volume of the battery by Archimedes method after 50 cycles) / (volume of the battery by Archimedes method before 1 cycle) (unit:%). In addition, the non-aqueous electrolyte secondary battery in which the non-aqueous electrolyte solution was so overflowing that it was not possible to inject the non-aqueous electrolyte solution as set was not subjected to cycle evaluation as an NG product.

  As shown in Table 1, the 60 ° C. 50 cycle maintenance ratio and the 60 ° C. 50 cycle volume change of the nonaqueous electrolyte secondary batteries produced in Examples 1 to 13 are the nonaqueous electrolyte solutions produced in Comparative Examples 1 to 10. It was better than those of secondary batteries. From this result, it became clear that the present embodiment provides a non-aqueous electrolyte secondary battery that can be driven for a long life.

  This embodiment can be used in all industrial fields that require a power source, and in industrial fields related to the transport, storage, and supply of electrical energy. Specifically, power supplies for mobile devices such as mobile phones and notebook computers; power supplies for transportation and transportation media such as trains, satellites, and submarines, including electric vehicles such as electric cars, hybrid cars, electric bikes, and electric assist bicycles A backup power source such as a UPS; a power storage facility for storing power generated by solar power generation, wind power generation, etc .;

a negative electrode b separator c positive electrode d negative electrode current collector e positive electrode current collector f positive electrode terminal g negative electrode terminal

Claims (8)

An electrode element in which a positive electrode and a negative electrode are arranged to face each other, a non-aqueous electrolyte, and an outer package containing the electrode element and the non-aqueous electrolyte, wherein the negative electrode is formed by a negative electrode binder and charge / discharge Non-aqueous electrolyte secondary containing a plurality of types of negative electrode active materials having different volume change rates, and the proportion of the negative electrode active material having the largest volume change rate is more than 5 parts by mass and less than 95 parts by mass of the whole negative electrode active material A battery manufacturing method comprising:
A first step of injecting the non-aqueous electrolyte into the exterior body containing the electrode element;
A second step of charging the cell obtained in the first step at least once;
A third step in which 5 hours or more have elapsed from the start time of the second step;
A fourth step of injecting the non-aqueous electrolyte having a mass of 0.5 to 2.0 times the A value defined below into the exterior body of the cell that has undergone the third step. A method for producing a non-aqueous electrolyte secondary battery.
A (g) = nonaqueous electrolyte density (g / ml) × [(cell volume at the start of the fourth step (ml)) − (cell volume at the end of the first step (ml))]   The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode active material having the largest volume change rate is silicon capable of forming an alloy with lithium.   The negative electrode active material comprises a carbon material (a) capable of occluding and releasing lithium, a metal (b) capable of forming an alloy with lithium, and a metal oxide (c) capable of occluding and releasing lithium. The manufacturing method of the nonaqueous electrolyte secondary battery of Claim 1 or 2 characterized by these. The said metal oxide (c) is a metal oxide which comprises the said metal (b), The manufacturing method of the nonaqueous electrolyte secondary battery of Claim 3 characterized by the above-mentioned. The method for producing a non-aqueous electrolyte secondary battery according to any one of claims 1 to 4, wherein the negative electrode binder is polyimide or polyamideimide. The method for producing a non-aqueous electrolyte secondary battery according to claim 1, wherein the outer package is an aluminum laminate film. The method for manufacturing a non-aqueous electrolyte secondary battery according to claim 1, wherein the electrode element has a planar laminated structure. The method for producing a non-aqueous electrolyte secondary battery according to any one of claims 1 to 7, wherein the non-aqueous electrolyte contains a fluorinated ether or a phosphate ester.

Images