JP5779455B2 - Lithium ion secondary battery - Google Patents

Description

  The present invention relates to a lithium ion secondary battery.

  Conventionally, lithium-ion secondary batteries are lightweight, large-capacity, and capable of high-speed charging / discharging. Therefore, lithium-ion secondary batteries are now widely used in mobile devices such as notebook computers and mobile phones, and in automobiles. Various studies have been made to improve high-speed charge / discharge characteristics.

  As such a lithium ion secondary battery, for example, as disclosed in FIG. 3 of Patent Document 1 (Japanese Patent Laid-Open No. 2008-288214), a positive electrode composed of a positive electrode active material layer and a metal foil, A separator type having a configuration in which a negative electrode composed of a negative electrode active material layer and a metal foil is laminated via a separator and the separator is impregnated with an electrolytic solution is known.

  On the other hand, for example, as disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2011-70788), an all-solid-type lithium ion secondary battery not including a separator and having a configuration in which a positive electrode, an electrolyte layer, and a negative electrode are stacked. Is also known.

  Here, in order to increase the capacity of the lithium ion secondary battery and improve the high-speed charge / discharge characteristics, the reaction between the positive electrode active material and the negative electrode active material and the electrolyte is rate-determined. It is important to make the electrode areas of the positive electrode and the negative electrode as large as possible, and paying attention to this point, in Patent Document 2 described above, an active material layer having a concavo-convex structure (a convex having a high aspect ratio applied in a line shape) A method for manufacturing an all-solid battery having an electrode having a three-dimensional structure including an active material portion) has been proposed.

JP 2008-288214 A JP 2011-70788 A

  However, in the separator-type lithium ion secondary battery in Patent Document 1 described above, when an active material layer having a concavo-convex structure as proposed in Patent Document 2 is employed for increasing capacity and high-speed charge / discharge characteristics. For example, there is a possibility that the opposing convex positive electrode active material portion enters the concave portion between the adjacent convex negative electrode active material portions and breaks the separator. If the separator is damaged, the positive electrode active material part and the negative electrode active material part may be short-circuited, and the battery function may be lost.

  That is, the active material layer having the concavo-convex structure of the all-solid-type lithium ion secondary battery proposed in Patent Document 2 is used as a separator-type lithium ion secondary battery as disclosed in Patent Document 1. It was difficult to adopt it as it was.

  In view of the above problems, an object of the present invention is to provide a separator-type lithium ion secondary that includes an active material layer having a concavo-convex structure with a high aspect ratio, and has high capacity and high-speed charge / discharge characteristics without damaging the separator. An object is to provide a battery.

In order to solve the above problems, the present inventors have
A first electrode having a first current collector and a first active material layer formed of a plurality of convex first active material portions provided on the first current collector;
A second electrode having a second current collector, and a second active material layer formed of a plurality of convex second active material portions provided on the second current collector, and the first electrode, Including a separator positioned between the second electrode,
The first electrode and the second electrode are laminated so that the convex first active material portion faces between the adjacent convex second active material portions,
The size of the convex first active material part is larger than the space between the convex second active material parts, and the convex first active material part does not enter between the convex second active material parts. ,
A lithium ion secondary battery is provided.

  Even if the lithium ion secondary battery of the present invention having such a configuration includes an active material layer having a concavo-convex structure with a high aspect ratio, the convex first active material portion in the first active material layer is opposed to the first active material layer. Separator type lithium ion secondary that cannot penetrate between adjacent convex second active material portions in the second active material layer, can effectively prevent damage to the separator, and has high capacity and high-speed charge / discharge characteristics A battery can be reliably realized.

In the lithium ion secondary battery of the present invention, the widths Wa ₁ and Wa _{2 of} two adjacent sides of the upper end of the convex first active material portion and the convex second active material portion facing the two sides. The distances Wb ₁ and Wb ₂ between the upper ends (spaces) of
Relational expression (1): Wa ₁ > Wb ₁ and Relational expression (2): Wa ₂ > Wb ₂
It is preferable to satisfy.

  The lithium ion secondary battery of the present invention having such a configuration includes the first active material layer when, for example, the convex first active material portion and the convex second active material portion are linear or substantially prismatic. The convex first active material portion in the second active material layer cannot enter between the adjacent convex second active material portions, and the separator can be effectively prevented from being damaged. A separator-type lithium ion secondary battery having excellent discharge characteristics can be reliably realized.

Therefore, in the lithium ion secondary battery of the present invention, even if the convex first active material portion and the convex second active material portion are each linear, the convex first active material portion and the Each of the convex second active material portions may have a substantially prismatic shape.
In the case of a linear shape, that is, in the lithium ion secondary battery of the present invention, each of the convex first active material portion and the convex second active material portion is configured to form a so-called line and space pattern. Has been. At this time, a convex 1st active material part will be located facing the recessed part between adjacent convex 2nd active material parts.

  The lithium ion secondary battery of the present invention having such a configuration can increase the contact area between the convex first active material portion and the convex second active material portion and the electrolyte layer, and has a large capacity. Thus, a separator-type lithium ion secondary battery having excellent high-speed charge / discharge characteristics can be realized more reliably.

In the lithium ion secondary battery of the present invention, the widths Wa ₁ and Wa _{2 of the} convex first active material portion are 100 to 150 μm, and the distance Wb between the upper ends of the convex second active material portions. it ₁ and Wb ₂ are 50～90Myuemu, is preferred.

  In the lithium ion secondary battery of the present invention having such a configuration, the above relational expression is more reliably satisfied, and the convex first active material portion in the first active material layer is adjacent in the opposing second active material layer. It is possible to more reliably realize a separator type lithium ion secondary battery that cannot penetrate between the convex second active material portions, can effectively prevent the breakage of the separator, and has a large capacity and excellent high-speed charge / discharge characteristics. it can. Moreover, it is easy to ensure these heights with respect to the width of the convex first active material portion and the convex second active material portion, and an active material layer having a high aspect ratio and a high aspect ratio uneven structure can be provided. .

  In the lithium ion secondary battery of the present invention, it is preferable that the height Ha of the convex first active material portion and the height Hb of the convex second active material portion are 50 to 100 μm, respectively. .

  In the lithium ion secondary battery of the present invention having such a configuration, the resistance of the convex first active material portion and the convex second active material portion does not increase excessively, and the decrease in charge / discharge capacity can be prevented. There is a merit that you can.

  According to the present invention, it is possible to realize a separator-type lithium ion secondary battery that includes an active material layer having a concavo-convex structure with a high aspect ratio and that has a large capacity and excellent high-speed charge / discharge characteristics without damaging the separator. .

It is a schematic longitudinal cross-sectional view of one embodiment of the lithium ion secondary battery of the present invention. In the lithium ion secondary battery 1 shown in FIG. 1, the positional relationship between the convex cathode active material portion 16a upper top and linear linear convex negative electrode active material portion 12a appear by projecting in the direction of arrow Z ₁ FIG. It is a schematic diagram which shows a mode that the convex negative electrode active material part 12a (negative electrode active material layer 12) is formed by the nozzle dispensing method about the lithium ion secondary battery 1 shown in FIG. In a variation of the lithium ion secondary battery of the present invention, substantially square and the upper end of a portion of a substantially prismatic convex negative electrode active material portion 22a appear by projecting in the direction of the arrow Z ₁ in FIG. 1 as well as FIG. 2 It is the schematic which shows the positional relationship with the upper end of the column-shaped convex-shaped positive electrode active material part 26a.

  Hereinafter, an embodiment of the lithium ion secondary battery of the present invention will be described with reference to the drawings, but the present invention is not limited to these. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description may be omitted. Moreover, since the drawings are for conceptual description of the present invention, the dimensions, ratios, or numbers may be exaggerated or simplified as necessary for easy understanding. Furthermore, in this specification, the X, Y, and Z coordinate directions are defined as shown in FIGS.

In the present embodiment, the present invention will be described using a lithium ion secondary battery having the structure shown in FIG. 1 as a representative. FIG. 1 is a schematic longitudinal sectional view of an embodiment of the lithium ion secondary battery of the present invention. Also, FIG. 2, in the lithium ion secondary battery 1 shown in FIG. 1, a convex positive upper (surface) and linear linear convex negative electrode active material portion 12a appear by projecting in the direction of arrow Z ₁ It is the schematic which shows the positional relationship with the upper end (surface) of the active material part 16a.

  Further, although details will be described later, FIG. 3 is a schematic diagram showing how the convex negative electrode active material portion 12a (negative electrode active material layer 12) is formed by the nozzle dispensing method for the lithium ion secondary battery 1 shown in FIG. 4 is a modification of the lithium ion secondary battery 1 shown in FIG. 1, and the upper end of the substantially prismatic convex negative electrode active material portion 22a and the upper end of the substantially prismatic convex positive electrode active material portion 26a. It is the schematic which shows these positional relationships.

  As shown in FIG. 1, the lithium ion secondary battery 1 of the present embodiment includes a negative electrode (first electrode) A, a separator 20, and a positive electrode (second electrode) C, and the negative electrode A and the positive electrode C. The electrolytic solution layer 14 is formed by filling the electrolytic solution between the separator 20 and the separator 20 is impregnated with the electrolytic solution.

  The negative electrode A includes a negative electrode current collector (first current collector) 10 and a plurality of linear convex negative electrode active material portions (first active material portions) provided on the negative electrode current collector 10 with spaces. The positive electrode C is composed of a positive electrode current collector (second current collector) 18 and a space on the positive electrode current collector 18. And a positive electrode active material layer (second active material layer) 16 composed of a plurality of linear convex positive electrode active material portions (second active material portions) 16a. That is, the convex negative electrode active material portion 12a and the convex positive electrode active material portion 16a in the present embodiment are formed to have a so-called line and space pattern shape.

Here, in the lithium ion secondary battery 1 of the present embodiment, as shown in FIG. 1, the negative electrode A and the positive electrode C are opposed to the convex negative electrode material portion 12a between the adjacent convex positive electrode material portions 16a. The most important features are the widths (lengths) Wa ₁ and Wa ₂ of the adjacent two sides L ₁ and L ₂ at the upper end of the convex negative electrode active material portion 12a, and the convex positive electrode active material portion. The distances Wb ₁ and Wb ₂ between the upper ends (spaces) of 16a are as shown in FIG.
Relational expression (1): Wa ₁ > Wb ₁ and Relational expression (2): Wa ₂ > Wb ₂
It is in the point that satisfies.

To be more specific, in a lithium ion secondary battery 1 of this embodiment, as shown in FIG. 2, a linear convex negative electrode active material portion 12a, projecting in the direction of the arrow Z ₁ in FIG. 1 When viewed, it is a substantially rectangular shape having two sides L ₁ and L ₂ which are adjacent and orthogonal to each other, and has an elongated strip shape. Similarly, the linear convex positive electrode active material portion 16a, and try to project in the direction of the arrow Z ₁ in FIG. 1, a substantially rectangular shape having two sides perpendicular to adjacent, elongated strip-like shape Have.

The convex faces the side L ₁ of the negative electrode active material portion 12a and between the upper end of the convex cathode active material portion 16a (space) M ₁ is located, the sides L ₁ of the width Wa of the convex negative electrode active material portion 12a _1, the distance Wb ₁ between the upper end of the convex cathode active material portion 16a (space) _{M 1,} but equation _(1): satisfies Wa 1> Wb _1.

Further, at a position opposite to the side L ₂ of the convex negative electrode active material portion 12a, between the upper ends of the convex cathode active material portion 16a (space) M ₂ is not provided, i.e., convex positive electrode active material portion distance Wb ₂ of the upper end between (space) _{M 2} of 16a is zero, the width Wa ₂ sides _{L 2} of the convex negative electrode active material portion 12a, between the upper ends of the convex cathode active material portion 16a (space) _{M 2} The distance Wb ₂ (= 0) satisfies the relational expression (2): Wa ₂ > Wb ₂ .

  Since the lithium ion secondary battery 1 of the present embodiment has the above-described configuration, even if the convex negative electrode active material portion 12a and the convex positive electrode active material portion 16a have a high aspect ratio, the convexity The negative electrode active material portion 12a cannot enter the concave portion between the adjacent convex positive electrode active material portions 16a, and thus the convex negative electrode active material portion 12a and the convex positive electrode active material portion 16a break through the separator 20. The separator type lithium ion secondary battery 1 can be effectively prevented from being damaged, and has high capacity, high-speed charge / discharge characteristics, and high reliability.

In the lithium ion secondary battery 1 of the present embodiment, the width Wa ₁ of the convex negative electrode active material portion 12a is 100 to 150 μm, and the distance Wb ₁ between the upper ends (spaces) of the convex positive electrode active material portion 16a. Is preferably 50 to 90 μm. Thereby, the lithium ion secondary battery 1 of the present embodiment more reliably satisfies the relational expression (1), and the widths of the convex negative electrode active material portion 12a and the convex positive electrode active material portion 16a are as follows. It is easy to secure the height, and a high aspect ratio can be realized more reliably.

  Moreover, in the lithium ion secondary battery 1 of this embodiment, it is preferable that the height Ha of the convex negative electrode active material part 12a and the height Hb of the convex positive electrode active material part 16a are 50-100 micrometers, respectively. Thereby, the resistance of the convex negative electrode active material portion 12a and the convex positive electrode active material portion 16a does not increase excessively, and a decrease in charge / discharge capacity can be prevented.

  Here, as the negative electrode current collector 10, a known material in the technical field to which the present invention belongs can be used, but any metal film such as an aluminum foil may be used. Although not shown, the negative electrode current collector 10 may be formed on the surface of an insulating base material. As such a base material, a flat plate member formed of an insulating material may be used. Examples of such an insulating material include resin, glass, ceramics, and the like. The base material may be a flexible flexible substrate.

  As shown in FIGS. 1 to 3, the negative electrode active material layer 12 includes a plurality of linear convex negative electrode active materials formed on the negative electrode current collector 10 so as to extend along the Y direction. It consists of part 12a.

As the negative electrode active material contained in the convex negative electrode active material portion 12a, those commonly used in the technical field of the present invention can be used. For example, metals, metal fibers, carbon materials, oxides, nitrides, silicon, silicon compounds , Tin, tin compounds, various alloy materials, and the like. Of these, oxides, carbon materials, silicon, silicon compounds, tin, tin compounds and the like are preferable in view of the capacity density. Examples of the oxide include lithium titanate represented by the formula: Li ₄ Ti ₅ O ₁₂ . Examples of the carbon material include various natural graphite (graphite), coke, graphitizing carbon, carbon fiber, spherical carbon, various artificial graphite, amorphous carbon, and the like. Examples of the silicon compound include a silicon-containing alloy, a silicon-containing inorganic compound, a silicon-containing organic compound, a solid solution, and the like. Specific examples of the silicon compound include, for example, silicon oxide represented by SiO _a (0.05 <a <1.95), silicon and Fe, Co, Sb, Bi, Pb, Ni, Cu, Zn, Ge, An alloy containing at least one element selected from In, Sn, and Ti, silicon, silicon oxide, or a part of silicon contained in the alloy is B, Mg, Ni, Ti, Mo, Co, Ca, Cr, Cu, Examples thereof include silicon compounds or silicon-containing alloys substituted with at least one element selected from Fe, Mn, Nb, Ta, V, W, Zn, C, N, and Sn, and solid solutions thereof. Examples of the tin compound include SnO _b (0 <b <2), SnO ₂ , SnSiO ₃ , Ni ₂ Sn ₄ , Mg ₂ Sn, and the like. A negative electrode active material may be used individually by 1 type, and may be used in combination of 2 or more type as needed.

  Moreover, the convex negative electrode active material part 12a may contain the conductive support agent. As the conductive auxiliary agent, those commonly used in the technical field of the present invention can be used. For example, natural graphite, graphite such as artificial graphite, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black Carbon blacks such as carbon fibers, conductive fibers such as carbon fibers and metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide, conductive metal oxides such as titanium oxide, and phenylene derivatives Organic conductive materials such as A conductive agent can be used individually by 1 type, or can be used in combination of 2 or more type as needed.

  As described above, the lithium ion secondary battery 1 of the present embodiment is opposed to the negative electrode A composed of the negative electrode current collector 10 and the negative electrode active material layer 12, and the positive electrode active material layer 16 and the positive electrode current collector. 18 is stacked, and the electrolyte layer 14 and the separator 20 are provided between the negative electrode A and the positive electrode C. Therefore, in the lithium ion secondary battery 1 of the present embodiment, there is an airtight space between the negative electrode A and the positive electrode C, and the electrolytic solution layer 14 is formed by filling the space with the electrolytic solution. have.

  As the separator 20, a porous film or a nonwoven fabric exhibiting excellent high rate discharge performance can be used alone or in combination. Examples of the material constituting the separator 20 include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and vinylidene fluoride. Perfluorovinyl ether copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, vinylidene fluoride-trifluoroethylene copolymer, vinylidene fluoride-fluoroethylene copolymer, vinylidene fluoride-hexafluoroacetone copolymer, Vinylidene fluoride-ethylene copolymer, vinylidene fluoride-propylene copolymer, vinylidene fluoride-trifluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene-hex Hexafluoropropylene copolymers, vinylidene fluoride - ethylene - can be mentioned tetrafluoroethylene copolymer.

  For the separator 20, for example, a polymer gel composed of a polymer such as acrylonitrile, ethylene oxide, propylene oxide, methyl methacrylate, vinyl acetate, vinyl pyrrolidone, and polyvinylidene fluoride and an electrolyte may be used.

As the electrolytic solution constituting the electrolytic solution layer 14, a conventionally known electrolytic solution containing a lithium salt and an organic solvent can be used. Examples of the lithium salt include lithium hexafluorophosphate (LiPF ₆ ), lithium perchlorate (LiClO ₄ ), and lithium bistrifluoromethanesulfonylimide (LiTFSI). Examples of the organic solvent include ethylene carbonate, diethylene carbonate, and ethyl methyl carbonate, and a mixture thereof can also be used.

  On the positive electrode current collector 18, in the same manner as the negative electrode active material layer 12 made of the convex negative electrode active material 12a on the negative electrode current collector 10, the positive electrode made of the convex positive electrode active material portion 16a containing the positive electrode active material material. An active material layer 16 is provided.

  As the positive electrode current collector 18, a known material in the technical field to which the present invention belongs can be used, but a metal film such as a copper foil may be used. Similarly to the negative electrode current collector 10, the positive electrode current collector 18 may be formed on the surface of an insulating base material. As such a base material, a flat plate member formed of an insulating material may be used. Examples of such an insulating material include resin, glass, ceramics, and the like. The base material may be a flexible flexible substrate.

Examples of the positive electrode active material (powder) included in the convex positive electrode active material portion 16a include lithium-containing composite metal oxides, chalcogen compounds, and manganese dioxide. The lithium-containing composite metal oxide is a metal oxide containing lithium and a transition metal or a metal oxide in which a part of the transition metal in the metal oxide is substituted with a different element. Here, examples of the different elements include Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B, and Mn, Al, Co, Ni, Mg and the like are preferable. One kind or two or more kinds of different elements may be used. Among these, lithium-containing composite metal oxides can be preferably used. The lithium-containing composite metal oxide, for _{example, Li x CoO 2, Li x} NiO 2, Li x MnO 2, Li x Co y Ni 1-y O 2, Li x Co y M 1-y O z, Li x _{Ni 1-y M y O z} , Li x Mn 2 O 4, Li x Mn 2-y M y O 4, LiMPO 4, Li 2 MPO 4 F ( in the respective formulas, for example, M is Na, Mg, Sc , Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, V and B. At least one selected from the group consisting of 0 <x ≦ 1.2 and 0 <y ≦ 0. 9, 2.0 ≦ z ≦ 2.3), LiMeO ₂ (wherein Me = MxMyMz; Me and M are transition metals, x + y + z = 1), and the like. Specific examples of the lithium-containing composite metal oxide include LiNi _1/3 Mn _1/3 Co _1/3 O ₂ and LiNi _0.8 Co _0.15 Al _0.05 O ₂ . Here, x value which shows the molar ratio of lithium in each said formula increases / decreases by charging / discharging. Examples of the chalcogen compound include titanium disulfide and molybdenum disulfide. A positive electrode active material can be used individually by 1 type, and may use 2 or more types together. The positive electrode active material layer 16 may include the conductive additive described above with respect to the negative electrode active material layer 12.

  As described above, the negative electrode current collector 10, the negative electrode active material layer 12, the electrolyte solution layer 14, the separator 20, the electrolyte solution layer 14, the positive electrode active material layer 16, and the positive electrode current collector 18, the lithium ion A secondary battery 1 is formed.

  Although not shown, this lithium ion battery secondary battery 1 may be provided with a tab electrode as appropriate, and a plurality of lithium ion battery secondary batteries 1 are connected in series and / or in parallel. An ion secondary battery device can also be configured.

  The lithium ion secondary battery 1 of the present embodiment having such a structure can be configured to be thin and bendable. Further, since the negative electrode active material layer 12 and the positive electrode active material layer 16 have a three-dimensional structure having irregularities as illustrated, the surface area with respect to the volume is increased, so that the negative electrode active material layer 12 and the positive electrode active material layer 16 respectively A large contact area with the electrolyte solution 14 can be secured, and high efficiency and high output can be obtained. Thus, the lithium ion secondary battery 1 of this embodiment is small and has high performance.

  Next, a method for manufacturing the electrode and the lithium ion secondary battery 1 in the above-described embodiment will be described. When manufacturing the lithium ion secondary battery 1 of the present embodiment, first, the negative electrode active material layer 12 including the convex negative electrode active material portion 12a is formed on the negative electrode current collector 10 to produce the negative electrode A, and the positive electrode A positive electrode C is fabricated by forming the positive electrode active material layer 16 including the convex positive electrode active material portion 16 a on the current collector 18.

  Then, as shown in FIG. 1, the negative electrode A and the positive electrode C are separated so that the convex negative electrode material portion 12 a faces the convex positive electrode material portion 16 a adjacent to each other in the positive electrode active material layer 16. 20 through. An airtight sealed space is formed between the negative electrode A and the positive electrode C, and the electrolyte solution 14 is formed by filling the electrolyte solution therein, and the separator 20 is also impregnated with the electrolyte solution.

  For example, (a) a negative electrode active material material containing a negative electrode active material is linearly moved with respect to the negative electrode current collector 10 so that the negative electrode active material portion 12a moves in a linear manner on the negative electrode current collector 10. A coating step for forming a plurality of convex negative electrode active material portions 12a made of an active material (that is, a coating step using a nozzle dispensing method), and (a) a drying step for drying the convex negative electrode active material portions 12a. Can be formed.

The coating step (A), as shown in FIG. 3 (a), by transporting the negative electrode current collector 10 in the direction of arrow Y _1, the relative movement of the nozzle 40 with respect to the negative electrode current collector 10 Let On the surface of the negative electrode current collector 10 being conveyed, a paste-like negative electrode active material is discharged from the nozzle 40 so as to form a convex negative electrode active material portion 12a. In the present embodiment, the position of the nozzle 40 is fixed, and the nozzle 40 is moved relative to the negative electrode current collector 10 by transporting the negative electrode current collector 10.

The paste-like negative electrode active material is composed of a mixture obtained by stirring and mixing (kneading) the negative electrode active material, the conductive auxiliary agent, a binder, a solvent, and the like by a conventional method, and a nozzle. What is necessary is just to have various viscosity in the range which can be discharged from 40. In the present embodiment, for example, it is preferable that the shear rate is 1 s ⁻¹ and the lower limit is about 10 Pa · s and the upper limit is about 10000 Pa · s. Each component may be dissolved or dispersed in a solvent (including the case where a part is dissolved and the remainder is dispersed).

  Further, the solid content ratio of the negative electrode active material used in the coating step can have various solid content ratios so that the negative electrode active material can be discharged from the nozzle 40, but the solid content ratio at the wet point of the mixture. It is preferable that it is 60 mass%, for example.

  These viscosities and solid content ratios vary depending on the types and blending amounts, dimensions, shapes, etc. of components such as the negative electrode active material, conductive auxiliary agent, binder and solvent, but the negative electrode active material and the conductive auxiliary agent. And the length of the kneading time when the binder, the solvent and the like are agitated and mixed (kneaded) by a conventional method.

  As the binder, those commonly used in the technical field of the present invention can be used. For example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide , Polyacrylonitrile, polyacrylic acid, polyacrylic acid methyl ester, polyacrylic acid ethyl ester, polyacrylic acid hexyl ester, polymethacrylic acid, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid hexyl ester, poly Vinyl acetate, polyvinyl pyrrolidone, polyether, polyether sulfone, polyhexafluoropropylene, styrene-butadiene rubber, ethylene-propylene diene copolymer, carboxymethyl cellulose And the like. Copolymers of monomer compounds selected from tetrafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, hexadiene, etc. May be used as a binder. A binder can be used individually by 1 type, or can be used in combination of 2 or more type as needed.

As the solvent, it is preferable to use an organic solvent excluding water so as not to decompose lithium hexafluorophosphate (LiPF ₆ ) and the like contained in the electrolyte layer 14. As the organic solvent, those commonly used in the technical field of the present invention can be used, and examples thereof include dimethylformamide, dimethylacetamide, methylformamide, N-methyl-2-pyrrolidone (NMP), dimethylamine, acetone, and cyclohexanone. Can be mentioned. An organic solvent can be used individually by 1 type, or can mix and use 2 or more types.

  Here, FIG. 3A is a side view schematically showing a state in which the convex negative electrode active material portion 12a constituting the negative electrode active material layer 12 is formed by the nozzle dispensing method (that is, the negative electrode collection being conveyed). FIG. 3B shows a convex negative electrode active material portion constituting the negative electrode active material layer 12 by a nozzle dispensing method. FIG. 3B is a view seen when viewed from the X direction substantially parallel to the main surface of the electric body 10. It is a perspective view which shows typically a mode that 12a is formed.

In this nozzle dispensing method, a nozzle 40 provided with a plurality of discharge ports for discharging a negative electrode active material that is a coating liquid is disposed above the negative electrode current collector 10, and a certain amount of negative electrode active material is discharged from the discharge port. While discharging the material, the negative electrode current collector 10 is conveyed at a constant speed in the direction of the arrow Y ₁ relative to the nozzle 40. By doing so, a plurality of linear convex material active portions 12a made of the negative electrode active material material are formed on the negative electrode current collector 10 along the Y direction, thereby forming a striped line and space pattern shape. It is applied so that

  If a plurality of discharge ports are provided in the nozzle 40, a plurality of linear convex negative electrode active material portions 12a can be formed into a stripe shape, and the negative electrode current collector 10 is continuously conveyed, A linear convex negative electrode active material portion 12 a can be formed in a stripe shape on the entire surface of the electric body 10.

  Since the plurality of linear convex material active portions 12a made of the negative electrode active material formed as described above are still in the state of a coating film containing a solvent or the like, the convex material active portions 12a are provided. The negative electrode current collector 10 is conveyed so as to pass through a lower region such as a blower as a drying means, and a drying process is performed by dry air. Thereby, the negative electrode A including the negative electrode current collector 10 and the negative electrode active material layer 12 including the linear convex material active portion 12a formed on the surface of the negative electrode current collector 10 is obtained.

  A person skilled in the art can appropriately select the drying temperature and drying time in the drying step. The drying temperature should just be the range which can dry the convex material active part 12a, and can fix the shape, for example, it exists in the range of 5 to 150 degreeC, Preferably it exists in the range of normal temperature (23 degreeC) to 80 degreeC. Any temperature is acceptable. Further, the drying time can be controlled by the conveyance speed of the negative electrode current collector 10.

  Next, the formation of the positive electrode active material layer 16 on the positive electrode current collector 18 can be performed in the same manner as the formation of the negative electrode active material layer 12 on the negative electrode current collector 10. The negative electrode A and the positive electrode C obtained as described above are laminated in a state where the negative electrode active material layer 12 and the positive electrode active material layer 16 are opposed to each other through a separator 20 in an airtight space. In addition, the electrolytic solution layer 14 is formed by filling the space with the electrolytic solution. Thus, the lithium ion secondary battery 1 of this embodiment is created.

≪Deformation mode≫
As mentioned above, although the example of embodiment of this invention was demonstrated, this invention is not limited only to these. For example, in the above-described embodiment, the case where the convex negative electrode active material portion 12a and the convex positive electrode active material portion 16a are linear has been described, but the convex negative electrode active material portion and the convex positive electrode active material portion are, for example, approximately It may be prismatic.

Here, in FIG. 4, as a modified embodiment of the lithium ion secondary battery 1 of the above embodiment, a portion of the substantially quadrangular prism convex anode appear by projecting in the direction of the arrow Z ₁ in FIG. 1 as well as FIG. 2 The schematic which shows the positional relationship of the upper end of the active material part 22a and the upper end of the substantially square columnar convex positive electrode active material part 26a is shown.

In this modification, as shown in FIG. 4, as in the above embodiment, the convex negative electrode material portions 22a are laminated so as to face each other between the adjacent convex positive electrode material portions 26a. The widths (lengths) Wa ₁ and Wa _{2 of} two adjacent sides L ₁ and L ₂ of the material part 22a and the distances Wb ₁ and Wb ₂ between the upper ends (spaces) of the convex positive electrode active material part 26a are shown in FIG. As shown in Figure 4,
Relational expression (1): Wa ₁ > Wb ₁ and Relational expression (2): Wa ₂ > Wb ₂
Meet.

In more detail, in this modified embodiment, the convex negative electrode active material portion 22a of the substantially rectangular columnar, looking in a manner similar to that projected from the direction of arrow Z ₁ of Figure 1 in the above embodiment, adjacent to It has a substantially quadrangular shape having two sides L ₁ and L ₂ orthogonal to each other (see FIG. 4). Similarly, substantially rectangular columnar convex positive electrode active material portion 26a also, looking in a manner similar to that projected from the direction of arrow Z ₁ of Figure 1 in the above embodiment, substantially square with two sides orthogonal and adjacent It has a shape.

The convex faces the side L ₁ of the negative electrode active material portion 22a and between the upper end of the convex cathode active material portions 26a (space) M ₁ is located, the sides L ₁ of the width Wa of the convex negative electrode active material portion 22a _1, the distance Wb ₁ between the upper end of the convex cathode active material portions 26a (space) _{M 1,} but equation _(1): satisfies Wa 1> Wb _1.

Further, at a position opposite to the side L ₂ of the convex negative electrode active material portion 22a is convex positive electrode active material portion between the upper ends of 26a is (space) M ₂ located, the sides of the convex negative electrode active material portion 22a L ₂ the width Wa ₂ of the distance Wb ₂ convex between the positive electrode active material portion 26a upper end (space) _{M 2,} but equation _(2): meets Wa 2> Wb _2.

  Such a substantially quadrangular prism-shaped convex negative electrode active material portion 22a and a substantially quadrangular prism-shaped convex negative electrode active material portion 26a are also formed by controlling the discharge amount and timing of the nozzle by the nozzle dispensing method, as in the above embodiment. Can be formed.

  Since the lithium ion secondary battery 1 of this modification has the above-described configuration, even if the convex negative electrode active material portion 22a and the convex positive electrode active material portion 26a have a high aspect ratio, the convex The negative electrode active material portion 22a cannot enter the concave portion between the adjacent convex positive electrode active material portions 26a, and thus the convex negative electrode active material portion 22a and the convex positive electrode active material portion 26a break through the separator 20. The separator type lithium ion secondary battery 1 can be effectively prevented from being damaged, and has high capacity, high-speed charge / discharge characteristics, and high reliability.

  In addition to such embodiments and modifications, the lithium ion secondary battery of the present invention can take various forms within the scope of the technical idea of the present invention.

  For example, in the embodiment and the modification, the size of the convex negative electrode active material part is larger than the space between the convex positive electrode active material parts, and the convex negative electrode active material part does not enter between the convex positive electrode active material parts. However, in the lithium ion secondary battery of the present invention, on the contrary, the size of the convex positive electrode active material part is larger than the space between the convex negative electrode active material parts, and the convex positive electrode active material part is a convex negative electrode active material part. It is good also as a thing which has a structure which does not enter between substance parts.

  Moreover, in the said embodiment and the deformation | transformation aspect, although both the convex negative electrode active material part and the convex positive electrode active material part demonstrated the case where it was linear or substantially prismatic shape, the lithium ion secondary of this invention The battery may have a configuration in which one is linear and the other is a substantially prismatic shape.

  Moreover, in the said embodiment and deformation | transformation aspect, both a convex negative electrode active material part and a convex positive electrode active material part are formed in a fixed space on the negative electrode current collector and the positive electrode current collector, respectively. In the base portion of the convex negative electrode active material portion and the convex positive electrode active material portion (that is, the portion facing the negative electrode current collector and the positive electrode current collector), the adjacent convex negative electrode active material is described. The parts or the convex positive electrode active material parts may be continuous.

  In the above-described embodiment and modification, application by the nozzle dispensing method is applied to the formation of the convex negative electrode active material portion and the convex positive electrode active material portion that need to have a concavo-convex structure. It can be formed in a short time. Also, the nozzle dispensing method can be suitably applied to the creation of a fine pattern.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, the coating method applied in each step is not limited to the above, and other coating methods may be applied as long as they meet the purpose of the step. Further, for example, the electrolyte layer in the above-described embodiment and modification may be a gel electrolyte layer as long as a separator is used. In that case, the electrolyte material may be applied by spin coating or spray coating.

1 ... lithium ion secondary battery,
10 ... negative electrode current collector,
12 ... negative electrode active material layer,
12a, 22a ... convex negative electrode active material part,
14 ... electrolyte layer,
16 ... positive electrode active material layer,
16a, 26a ... convex positive electrode active material part,
18 ... positive electrode current collector,
20 ... negative electrode,
40: Nozzle.

Claims (5)

A first electrode having a first current collector and a first active material layer formed of a plurality of convex first active material portions provided on the first current collector;
A second electrode having a second current collector, and a second active material layer formed of a plurality of convex second active material portions provided on the second current collector, and the first electrode, Including a separator positioned between the second electrode,
The first electrode and the second electrode are laminated so that the convex first active material portion faces between the adjacent convex second active material portions,
Greater than the space between the size of the convex first active material portion is the convex second active material portion, have a structure in which the first active material portion and the convex does not enter between the convex second active material portion ,
Distances Wb ₁ and Wb between the widths Wa ₁ and Wa _{2 of} two adjacent sides of the upper end of the convex first active material part and the upper end (space) of the convex second active material part facing the two sides. ₂ and is,
Relational expression (1): Wa ₁ > Wb ₁ and
Relational expression (2): Wa ₂ > Wb ₂
Meeting,
A lithium ion secondary battery characterized by the above. A first electrode having a first current collector and a first active material layer formed of a plurality of convex first active material portions provided on the first current collector;
A second electrode having a second current collector and a second active material layer formed of a plurality of convex second active material portions provided on the second current collector; and
Including a separator positioned between the first electrode and the second electrode;
The first electrode and the second electrode are laminated so that the convex first active material portion faces between the adjacent convex second active material portions,
The size of the convex first active material part is larger than the space between the convex second active material parts, and the convex first active material part does not enter between the convex second active material parts. ,
The widths Wa ₁ and Wa _{2 of} two adjacent sides of the upper end of the convex first active material part are 100 to 150 μm, and between the upper ends (spaces) of the convex second active material part facing the two sides. The distances Wb ₁ and Wb ₂ are 50 to 90 μm,
A lithium ion secondary battery characterized by the above . The convex first active material part and the convex second active material part are each linear;
The lithium ion secondary battery according to claim 1 or 2. The convex first active material part and the convex second active material part are each substantially prismatic,
The lithium ion secondary battery according to claim 1 or 2. The height Ha of the convex first active material portion and the height Hb of the convex second active material portion are 50 to 100 μm, respectively.
The lithium ion secondary battery according to any one of claims 1 to 4.

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