JP2019212572A - Secondary battery and method of manufacturing the same - Google Patents

Abstract

To provide a secondary battery having a novel structure.SOLUTION: A secondary battery includes: a plurality of columnar first electrodes including a first electrode active material, the first electrodes being arranged in a predetermined direction; a second electrode including a second electrode active material, the second electrode being arranged to face the first electrode; an electrolyte having ion conductivity, covering the first electrode and interposed between the first electrode and the second electrode; and a connecting part comprising at least an electrolyte and connecting the first electrodes.SELECTED DRAWING: Figure 1

Description

  The invention disclosed in this specification relates to a secondary battery and a manufacturing method thereof.

  Conventionally, this type of secondary battery includes a positive electrode composed of a current collecting member and an active material-containing layer, a negative electrode composed of a current collecting member and an active material-containing layer, and an electrolyte layer that also serves as a separator. A plurality of unit cells stacked and held in a sealed state in a predetermined case and packaged has been proposed (see, for example, Patent Document 1). In this secondary battery, the electrode active material is subjected to a conductive treatment by coating the surface with a conductive additive and a binder, and the electrode active material is supported on the current collector surface by a dry method. And enables high energy density and high power density. In addition, as such a secondary battery, a lithium ion supply core part including an electrolyte, and a current collector having a three-dimensional network structure formed so as to surround the outer surface of the core part and coated on the outer surface with an internal electrode active material. There has been proposed a cable type secondary battery including an internal electrode including an external electrode including an external electrode active material layer formed so as to surround the external surface of the internal electrode (see, for example, Patent Document 2). In this secondary battery, the electrolyte in the core portion easily penetrates into the active material of the electrode, and the capacity characteristics and cycle characteristics of the battery are excellent.

JP 2004-6285 A Special table 2014-532277 gazette

  Incidentally, in recent years, lithium secondary batteries have been desired to have higher capacities and higher energy densities per unit volume. For example, in order to increase the battery capacity of the secondary battery described in Patent Document 1 described above, it is necessary to further increase the amount of the active material layer. For example, when the active material layer is made thicker, the volume occupied by members not related to charging / discharging, such as separators and current collectors, can be suppressed as compared with a stack of more cells. In some cases, the conduction distance of ions becomes longer and the output decreases. On the other hand, when more cells having a relatively thin active material layer are stacked, although the ion conduction distance is short and high power can be handled, the volume occupied by members not related to charge / discharge increases, so the energy density is increased. It was difficult. Further, the lithium secondary battery of Patent Document 2 is said to be able to improve capacity characteristics and cycle characteristics, but it has not been sufficient, for example, to improve input / output characteristics. Thus, a secondary battery having a novel structure that is not a conventional structure has been demanded.

  This indication is made in view of such a subject, and it aims at providing a secondary battery which has a novel structure.

  As a result of diligent research to achieve the above-described object, the present inventors have found that a structure in which columnar electrodes are arranged and joined by an electrolyte has a novel structure that can improve input / output characteristics. The inventors have found that the battery is a secondary battery, and have completed the invention disclosed in this specification.

That is, the secondary battery disclosed in this specification is
A plurality of columnar first electrodes including a first electrode active material and arranged in a predetermined direction;
A second electrode including a second electrode active material and disposed opposite to the first electrode;
An electrolyte having ion conductivity covering the first electrode and interposed between the first electrode and the second electrode;
A connecting portion configured by at least the electrolyte and connecting the first electrode and the first electrode;
It is equipped with.

The manufacturing method of the secondary battery disclosed in the present specification is as follows.
A plurality of columnar first electrodes including a first electrode active material are arranged in a predetermined direction with an interval to form a connecting portion for connecting the first electrode and the first electrode, and the second electrode active material is A second electrode including an ionic conductive electrolyte, and the electrolyte is disposed on the first electrode and between the first electrode and the second electrode so as to form the connecting portion. Including a connecting body forming step.

  The present disclosure can provide a secondary battery having a novel structure. Moreover, in such a secondary battery, input / output characteristics can be improved. The reason why such an effect can be obtained is presumed that, for example, the first electrode has a columnar shape, and the opposing area between the first electrode and the second electrode increases as compared with a planar (layered) electrode. Is done.

FIG. 2 is a schematic diagram illustrating an example of a secondary battery 20. FIG. 2 is a schematic diagram illustrating an example of a secondary battery 20. Explanatory drawing which shows an example of the manufacturing process of the secondary battery. Explanatory drawing which shows an example of the secondary battery 20B. An explanatory view showing an example of secondary battery 20C. Explanatory drawing which shows an example of the manufacturing process of the secondary battery 30 of a laminated structure. The schematic diagram of the ion movement of a columnar electrode and a laminated electrode.

(Secondary battery)
The secondary battery described in the present embodiment includes a plurality of columnar first electrodes including a first electrode active material and arranged in a predetermined direction, and a second electrode active material disposed opposite to the first electrode. A second electrode, an electrolyte having ionic conductivity, covering the first electrode, and interposed between the first electrode and the second electrode, and comprising at least an electrolyte and the first electrode and the first electrode And a connecting portion to be joined together. The secondary battery may include a columnar electrode assembly having a first electrode, a second electrode, an electrolyte, and a connecting portion. Further, the secondary battery may be provided with only one layer of the columnar electrode assembly. Further, in the secondary battery, the electrolyte is formed in layers on the first electrode, the second electrode is formed in layers on the electrolyte, and an electrode body having the first electrode, the electrolyte, and the second electrode is provided. It is good also as what has the structure of the columnar electrode coupling body connected by the connection part. The first electrode may be a negative electrode or a positive electrode, but is preferably a negative electrode. The second electrode may be a positive electrode or a negative electrode, but is preferably a positive electrode. For convenience of explanation, a lithium secondary battery using the first electrode as a negative electrode, the second electrode as a positive electrode, and lithium ions as a carrier will be described below as a main example.

  The first electrode may be a negative electrode that is a columnar body including a first electrode active material (negative electrode active material). The first electrode may be columnar, and the cross section thereof may be circular or elliptical, or may be polygonal such as square or hexagonal. In the secondary battery, a plurality of columnar first electrodes are arranged in a predetermined direction with a predetermined interval. The first electrode may include a carbonaceous material as the first electrode active material. Examples of the carbonaceous material include one or more of cokes, glassy carbons, graphites, non-graphitizable carbons, and pyrolytic carbons. Of these, graphites such as artificial graphite and natural graphite are preferable. Moreover, it is good also as carbon fiber which has a graphite structure. As such a carbonaceous material, for example, a material in which crystals are oriented in a columnar axial direction (longitudinal direction) is preferable. Moreover, it is preferable that the crystal is radially oriented from the center to the outer peripheral surface when viewed in a cross-section in a direction orthogonal to the columnar axial direction. Alternatively, the columnar negative electrode may be a columnar composite oxide capable of occluding and releasing carrier ions. Examples of the composite oxide include lithium titanium composite oxide and lithium vanadium composite oxide. This negative electrode may have a conductive component formed on at least a part of its surface. With this conductive component, the conductivity can be further increased. The conductive component is not particularly limited as long as it is a highly conductive material. For example, a carbonaceous material or a metal may be used. Further, the first electrode may have a current collecting member such as a current collecting wire embedded therein, or may not have this current collecting member.

  This first electrode may satisfy 0.33 ≦ D / (D + L) where the diameter is D (μm) and the distance between the first electrodes is L (μm). When D / (D + L) satisfies this relationship, it is preferable because the area facing the second electrode can be further increased. This D / (D + L) is preferably larger from the viewpoint of the facing area, preferably 0.4 or more, and more preferably 0.5 or more. The first electrode may satisfy D / (D + L) <1. When D / (D + L) satisfies this relationship, the distance L between the first electrodes becomes larger. For example, when the connecting portion has flexibility, the columnar electrode assembly can be bent and the degree of freedom in shape is increased. Will be improved. This D / (D + L) is preferably smaller from the viewpoint of the degree of freedom of shape, preferably 0.9 or less, and more preferably 0.8 or less. The first electrode may have a diameter D (μm) in the range of 20 μm to 800 μm. When the diameter D is 20 μm or more, the formation process of the linked body can be facilitated, and when the diameter D is 800 μm or less, an increase in ion diffusion resistance in the electrode can be further suppressed, which is preferable. The diameter D is preferably 30 μm or more, and more preferably 50 μm or more. The diameter D is preferably 500 μm or less, and more preferably 300 μm or less. The distance L (μm) between the first electrodes may be in the range of 5 μm to 1500 μm, and is preferably in the range of 10 μm to 1000 μm.

The second electrode may be a positive electrode that includes the second electrode active material (positive electrode active material) and is disposed to face the first electrode. This 2nd electrode is good also as what is formed in layers on electrolyte. Further, the second electrode may be a composite layer formed on the surface of the electrolyte. The second electrode may have a thickness in the range of 5 μm to 200 μm, and preferably in the range of 10 μm to 100 μm. The thickness of the second electrode may be appropriately determined according to the positive / negative electrode capacity ratio. For example, the second electrode may be formed by mixing a positive electrode active material, and, if necessary, a conductive material and a binder. Examples of the positive electrode active material include a material capable of occluding and releasing lithium as a carrier. Examples of the positive electrode active material include a compound having lithium and a transition metal, such as an oxide containing lithium and a transition metal element, and a phosphate compound containing lithium and a transition metal element. Specifically, a lithium manganese composite oxide whose basic composition formula is Li _(1-x) MnO ₂ (0 ≦ x ≦ 1, etc., the same shall apply hereinafter), Li _(1-x) Mn ₂ O _4, etc., basic composition Lithium cobalt composite oxide having a formula of Li _(1-x) CoO ₂ or the like, lithium nickel composite oxide having a basic composition formula of Li _(1-x) NiO ₂ or the like, and a basic composition formula of Li _(1-x) Co _a Ni _b Mn _c O ₂ (a> 0, b> 0, c> 0, a + b + c = 1), Li _(1-x) Co _a Ni _b Mn _c O ₄ (0 <a <1, 0 <b <1, 1 ≦ c <2, a + b + c = 2), etc., lithium cobalt nickel manganese composite oxide, basic composition formula of LiV ₂ O ₃ etc., lithium vanadium composite oxide, basic composition formula of V ₂ O ₅ etc. Transition metal oxides such as can be used. A lithium iron phosphate compound having a basic composition formula of LiFePO ₄ can be used as the positive electrode active material. Of these, lithium cobalt nickel manganese composite oxides such as LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ and LiNi _0.4 Co _0.3 Mn _0.3 O ₂ are preferable. The “basic composition formula” means that other elements such as components such as Al and Mg may be included.

  The conductive material included in the second electrode is not particularly limited as long as it is an electron conductive material that does not adversely affect battery performance. For example, graphite such as natural graphite (scale-like graphite, flake-like graphite) or artificial graphite, acetylene black , Carbon black, ketjen black, carbon whisker, needle coke, carbon fiber, metal (copper, nickel, aluminum, silver, gold, etc.) or a mixture of two or more thereof can be used. The binder serves to keep the active material particles and conductive material particles in a predetermined shape and includes, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, and the like. Fluorine resin, thermoplastic resin such as polypropylene and polyethylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM rubber, natural butyl rubber (NBR), etc. can be used alone or as a mixture of two or more. In addition, an aqueous dispersion of cellulose or styrene butadiene rubber (SBR), which is an aqueous binder, can also be used.

  In the second electrode, the content of the positive electrode active material is preferably higher, preferably 70% by mass or more, and more preferably 80% by mass or more with respect to the entire mass of the second electrode. The content of the conductive material is preferably in the range of 0% by mass to 20% by mass and more preferably in the range of 0% by mass to 10% by mass with respect to the total mass of the second electrode. In such a range, a decrease in battery capacity can be suppressed and sufficient conductivity can be imparted. Further, the content of the binder is preferably in the range of 0.1% by mass to 5% by mass with respect to the entire mass of the second electrode, and in the range of 0.2% by mass to 3% by mass. More preferably.

  The electrolyte has ion conductivity of ions (for example, lithium ions) that are carriers, covers the first electrode, and is interposed between the first electrode and the second electrode. This electrolyte insulates the first electrode from the second electrode. The electrolyte may be formed on the entire outer peripheral surface of the first electrode, and may be formed in layers on the first electrode. The electrolyte preferably has a thickness t (μm) in the range of 2 μm to 15 μm. When the thickness t is 2 μm or more, mechanical strength can be ensured, and a short circuit between the first electrode and the second electrode can be further prevented. Further, when the thickness t is 15 μm or less, the volume occupied by the electrolyte can be reduced, and the energy density can be improved. Moreover, the ion conducting distance can be further shortened, and the input / output performance can be further improved. This thickness t is preferably 3 μm or more, more preferably 5 μm or more from the viewpoint of mechanical strength. Further, the thickness t is preferably 12 μm or less, and more preferably 10 μm or less from the viewpoint of energy density.

The electrolyte is preferably a polymer having ionic conductivity and insulating properties. Examples of the electrolyte include polyvinylidene fluoride (PVdF), a copolymer of polyvinylidene fluoride and hexafluoropropylene (HFP), a polymethyl methacrylate (PMMA), and a copolymer of PMMA and an acrylic polymer. Is mentioned. For example, in the case of a copolymer of PVdF and HFP, a part of the electrolytic solution swells and gels this film, and becomes an ion conductive film. Further, the electrolyte may include an electrolytic solution that conducts ions as carriers. Examples of the electrolytic solution include a non-aqueous solvent. Examples of the solvent of the electrolytic solution include a solvent of a nonaqueous electrolytic solution. Examples of the solvent include carbonates, esters, ethers, nitriles, furans, sulfolanes and dioxolanes, and these can be used alone or in combination. Specifically, as carbonates, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate, vinylene carbonate, butylene carbonate, chloroethylene carbonate, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate, ethyl Chain carbonates such as n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate and t-butyl-i-propyl carbonate, cyclic esters such as γ-butyllactone and γ-valerolactone, Chain esters such as methyl formate, methyl acetate, ethyl acetate, methyl butyrate, ethers such as dimethoxyethane, ethoxymethoxyethane, diethoxyethane, acetonitrile, benzonitrile, etc. Nitriles, tetrahydrofurans such as tetrahydrofuran and methyltetrahydrofuran, sulfolanes such as sulfolane and tetramethylsulfolane, and dioxolanes such as 1,3-dioxolane and methyldioxolane. The electrolytic solution may be obtained by dissolving a supporting salt containing ions that are carriers of the secondary battery. Examples of the supporting salt include LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiSbF ₆ , LiSiF ₆ , LiAlF ₄ , LiSCN, Examples include LiClO ₄ , LiCl, LiF, LiBr, LiI, and LiAlCl ₄ . Among these, 1 selected from the group consisting of inorganic salts such as LiPF ₆ , LiBF ₄ and LiClO ₄ and organic salts such as LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) _3. From the viewpoint of electrical characteristics, it is preferable to use a seed or a combination of two or more salts. The supporting salt preferably has a concentration in the electrolytic solution of 0.1 mol / L or more and 5 mol / L or less, and more preferably 0.5 mol / L or more and 2 mol / L or less.

Alternatively, the electrolyte may be a solid electrolyte. As the solid electrolyte, for example, an inorganic solid electrolyte, a mixed material of an organic polymer electrolyte and an inorganic solid electrolyte, or an inorganic solid powder bound by an organic binder or the like can be used. Examples of the inorganic solid electrolyte include Li ₃ N, Li ₁₄ Zn (GeO ₄ ) ₄ called LISICON, sulfide Li _3.25 Ge _0.25 P _0.75 S ₄ , perovskite-type La _0.5 Li _0.5 TiO ₃ , (La _{2 / 3} Li _3x □ _{1 / 3-2x} ) TiO ₃ (□: atomic vacancy), Li ₇ La ₃ Zr ₂ O _{12 of} garnet type, LiTi ₂ (PO ₄ ) ₃ called NASICON type, Li _1.3 M _0.3 Ti _1.7 (PO ₃ ) ₄ (M = Sc, Al). In addition, Li ₇ P ₃ S ₁₁ obtained from glass of glass ceramics with a composition of 80Li ₂ S · 20P ₂ S ₅ (mol%), and Li ₁₀ Ge ₂ PS which is a sulfide-based material having high conductivity. ₂ and so on. For glass-based inorganic solid electrolytes, Li ₂ S—SiS ₂ , Li ₂ S—SiS ₂ —LiI, Li ₂ S—SiS ₂ —Li ₃ PO ₄ , Li ₂ S—SiS ₂ —Li ₄ SiO ₄ , Li ₂ S— _{P 2 S 5, Li 3 PO} 4 -Li 4 SiO 4, Li 3 BO 4 -Li 4 SiO 4, and the Li ₂ O and _{SiO 2, GeO 2, B 2} O 3, P 2 O 5 as a glass-based material Examples of the material that can be used as a network modifier. Further, Li ₂ S-GeS ₂ system as Chiorishikon solid electrolyte, Li ₂ S-GeS ₂ -ZnS _{system, Li 2 S-Ga 2 S} 2 _{system, Li 2 S-GeS 2 -Ga} 2 S 3 system, Li ₂ S -GeS ₂ -P ₂ S _{5 based, Li 2 S-GeS 2 -SbS} 5 _{system, Li 2 S-GeS 2 -Al} 2 S 3 system, Li ₂ S-SiS _{2 system, Li 2 S-P 2 S} 5 And solid electrolytes such as Li ₂ S—Al ₂ S ₃ , LiS—SiS ₂ —Al ₂ S ₃ , and Li ₂ S—SiS ₂ —P ₂ S ₅ .

  The connecting portion is a portion configured by at least an electrolyte and connecting the first electrode and the first electrode. It is preferable that the connecting portion is flexible enough to swing the first electrode. When the connecting portion has flexibility and the columnar electrode assembly is only one layer, the connection body can be bent, and the degree of freedom in shape is further improved. A second electrode may be formed on the connecting portion. That is, the second electrode may be formed across the plurality of first electrodes. This secondary battery may have a structure of a columnar electrode assembly in which an electrode body having a first electrode, an electrolyte, and a second electrode is connected by a connecting portion. The connecting portion may have a thickness in the range of 5 μm to 200 μm, and preferably in the range of 10 μm to 100 μm.

  A current collector may be connected to the first electrode or the second electrode. The current collector is a conductive member and is electrically connected to the end of the first electrode or the surface or end of the second electrode. This current collector includes, for example, carbon paper, aluminum, copper, titanium, stainless steel, nickel, iron, platinum, baked carbon, conductive polymer, conductive glass, etc., as well as adhesion, conductivity, and oxidation resistance ( For the purpose of improving the (reduction) property, a material obtained by treating the surface of aluminum or copper with carbon, nickel, titanium, silver, platinum, gold or the like can also be used. The shape of the current collector is not particularly limited as long as a plurality of first electrodes and second electrodes can be connected. For example, a plate shape, foil shape, film shape, sheet shape, net shape, punched or expanded And the like, lath bodies, porous bodies, foams, and formed bodies of fiber groups.

  In this secondary battery, the electrode capacity ratio (negative electrode capacity / positive electrode capacity), which is the ratio of the capacity of the first electrode active material (negative electrode active material) to the capacity of the second electrode active material (positive electrode active material), is 1.0. The range is preferably 1.5 or less and more preferably 1.2 or less. The thickness of the second electrode may be appropriately set according to the diameter of the first electrode and the electrode capacity ratio. The thickness of the second electrode may be, for example, the maximum thickness among the portions formed on the first electrode.

  1 and 2 are schematic views showing an example of the secondary battery 20. As shown in FIGS. 1 and 2, the secondary battery 20 includes a plurality of columnar first electrodes 21 arranged at predetermined intervals in a predetermined direction, and a second electrode disposed to face the first electrode 21. 22, an electrolyte 24 that covers the first electrode 21 and is interposed between the first electrode 21 and the second electrode 22, and a connecting portion 26 that connects the first electrode 21 and the first electrode 21. I have. Further, the secondary battery 20 may have a structure of the columnar electrode assembly 10 in which the electrode body 25 having the first electrode 21, the second electrode 22, and the electrolyte 24 is connected by the connecting portion 26. In the secondary battery 20 in which the connecting portion 26 has flexibility and includes only one layer of the columnar electrode connector 10, the columnar electrode connector 10 can be bent as shown in FIG.

(Method for manufacturing secondary battery)
The method for manufacturing a secondary battery according to the present disclosure may include a connecting body forming step for forming a columnar electrode connecting body and a current collecting portion forming step for forming a current collecting portion on each electrode. In each step, the above-described secondary battery member, composition, shape, structure, and the like are appropriately used. Note that the current collector forming step may be omitted as appropriate. In the coupling body forming step, the plurality of columnar first electrodes including the first electrode active material are arranged in a predetermined direction with an interval for forming a connecting portion for connecting the first electrode and the first electrode, The second electrode containing the electrode active material and the electrolyte having ion conductivity are placed on the first electrode and between the first electrode and the second electrode so as to form a connecting portion, and are heated and pressed. Process. In this step, only one layer of the columnar electrode assembly having the first electrode, the second electrode, the electrolyte, and the connecting portion may be formed. Further, in this step, when the diameter of the first electrode is D (μm) and the distance between the first electrodes is L (μm), the process may be performed to satisfy 0.33 ≦ D / (D + L). Good. In this step, it may be processed so as to satisfy D / (D + L) <1. The columnar electrode assembly obtained in this step may be sealed with a sealing member and injected with an electrolytic solution. In the current collector forming step, a process of forming a current collector (current collector tab) on the first electrode or forming a current collector on the outer surface of the second electrode is performed.

  FIG. 3 is an explanatory diagram illustrating an example of a manufacturing process of the secondary battery 20 having a columnar electrode assembly in which the columnar first electrodes 21 are coupled. In this manufacturing method, first, the second electrode layer 12 containing the second electrode active material formed on the support 13 and the electrolyte layer 14 are prepared (FIG. 3A). For the support 13, for example, a metal foil such as an Al foil can be used. Next, the second electrode layer 12 and the electrolyte layer 14 formed on the support 13 are bonded and pressed (FIG. 3B). Subsequently, the support 13 is peeled from the second electrode layer 12, whereby the positive electrode mixture is transferred to the electrolyte layer, and the second electrode layer 12 / electrolyte layer 14 assembly is obtained (FIG. 3C). Two pieces of this joined body are produced. Next, the columnar first electrodes 11 are aligned at a predetermined interval, and the upper and lower sides thereof are sandwiched between the bonded bodies (FIG. 3D), and the electrolyte layer 14 is bonded by thermal fusion or the like to obtain the columnar electrode connector ( FIG. 3 (e)). The current collector 28 is bonded to the second electrode 22 on the upper surface and the lower surface of the columnar electrode assembly. A current collecting tab 29 is connected to the current collector 28, a current collecting tab 27 is connected to the first electrode 21, placed in a sealed container, and sealed by injecting an electrolyte solution and having a columnar electrode assembly. The battery 20 can be obtained (FIG. 3F).

  In the secondary battery and the manufacturing method thereof detailed above, it is possible to provide a secondary battery having a novel structure. Moreover, in such a secondary battery, input / output characteristics can be improved. The reason why such an effect is obtained is that, for example, the first electrode has a columnar shape, and the facing area between the first electrode and the second electrode increases as compared with a planar (layered) electrode. Further, if the connecting portion has flexibility and only one layer of the columnar electrode assembly, it can be bent by the connecting portion 26, so that the degree of freedom of shape can be further increased. It can arrange | position to the member which has.

  In addition, this indication is not limited to the embodiment mentioned above at all, and as long as it belongs to the technical scope of this indication, it cannot be overemphasized that it can implement with a various aspect.

  For example, in the above-described embodiment, in the secondary battery, the columnar first electrode is described as a negative electrode, and the second electrode covering the first electrode is described as a positive electrode. However, the present invention is not limited to this, and the columnar first electrode is not limited to this. The positive electrode may be used, and the second electrode covering the first electrode may be used as the negative electrode.

  In the embodiment described above, the carrier of the secondary battery is lithium ion. However, the present invention is not particularly limited to this, and alkali metal ions such as sodium ions and potassium ions, and group II element ions such as calcium ions and magnesium ions. Also good. The positive electrode active material may include carrier ions. Moreover, although the electrolytic solution is a non-aqueous electrolytic solution, it may be an aqueous electrolytic solution.

  In the embodiment described above, an example in which the columnar negative electrode has a columnar shape has been described. However, the columnar negative electrode is not particularly limited thereto, and may have a shape such as a quadrangular column or a hexagonal column. FIG. 4 is an explanatory diagram showing an example of the secondary battery 20B having the quadrangular columnar first electrode 21B. FIG. 5 is an explanatory diagram showing an example of a secondary battery 20C having a hexagonal columnar first electrode 21C. A secondary battery can also be manufactured using the columnar first electrode having such a shape.

  Below, the example which produced the secondary battery mentioned above concretely is demonstrated as an experiment example. First, the result of considering the structure of the secondary battery will be described. Experimental Examples 4 to 11 and 13 are examples of the present disclosure, and Experimental Examples 1 to 3, 12, and 14 correspond to comparative examples.

(Experimental Examples 1-12)
First, the structure of the secondary battery 20 shown in FIG. 1 was examined. D / (D + L), which is the relationship between the diameter D (μm) of the cylindrical electrode (negative electrode) and the distance L (μm) between the electrodes, is determined, and the relationship between the opposing areas of the electrode and the second electrode (positive electrode) is determined. It was. Table 1 summarizes the relationship between D / (D + L) and the facing area of the positive and negative electrodes (Experimental Examples 1 to 11). A flat plate laminate (see FIG. 6) in which a flat positive and negative electrode and an electrolyte were laminated was used as Experimental Example 12.

  As shown in FIG. 1, consider a cell in which a plurality of cylindrical electrodes having a diameter D are arranged with an interval L and the entire width is X. The depth of the secondary battery, that is, the length of the cylindrical electrode is Y. The number of columnar electrodes aligned in the width X is represented by X / (D + L). Considering the surface area of the cylindrical electrode as the positive and negative electrode facing area, facing area = πD × Y × X / (D + L) (= cylindrical electrode side area × number), facing area = π (D / (D + L)) XXY. On the other hand, when considering a flat laminate cell having a width X and a depth Y (FIG. 6), the facing area = XY. For easy understanding, when X = Y = 1, when the opposing area of the flat plate stack cell is 1, the opposing area of the columnar electrode array cell is π (D / (D + L)). When the facing area of the columnar electrode array cell is calculated with D / (D + L) as a variable, when 0.33 ≦ D / (D + L) <1, that is, 0 <L ≦ 2D, the facing of the cylindrical electrode array cell It was found that the area was larger than that of the flat plate cell (see Table 1). In addition, the counter area ratio of Table 1 is the ratio of the area of the columnar electrode assembly when the plate laminate is 1 when the columnar electrode assembly and the plate laminate having the same outer circumference XY are compared. It represents.

(Experimental example 13)
Next, the validity of the calculation results was verified by producing cells of a columnar electrode assembly and a flat plate laminate. The cell of the columnar electrode assembly in Experimental Example 13 was manufactured in the order shown in FIG. First, a polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP) solution dissolved in N-methylpyrrolidone (NMP) is applied to a glass substrate, dried, and then peeled to remove PVdF-HFP having a thickness of 5 μm. An isolated membrane (electrolyte layer) was obtained. The positive electrode active material is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (NCM), the conductive material is carbon black, the binder is PVdF, and they are mixed at a mass ratio of 92: 5: 3. The positive electrode mixture was dispersed in NMP as a solvent. This positive electrode mixture paste was applied to an Al foil having a thickness of 15 μm and dried to prepare a positive electrode mixture layer (FIG. 3A). The positive electrode mixture layer formed on the Al foil and the electrolyte layer are bonded together, and after pressing (FIG. 3B), the Al foil is peeled off to transfer the positive electrode mixture to the electrolyte layer (FIG. 3C). ), A positive electrode mixture layer / electrolyte layer assembly was obtained. Two pieces of this joined body were produced. Next, five columnar carbon electrodes having a diameter of 500 μm are aligned at intervals of 500 μm, and the upper and lower sides thereof are sandwiched between the joined bodies (FIG. 3D), and the PVdF-HFP film is joined by thermal fusion, thereby connecting the columnar electrode assemblies. (FIG. 3E) was obtained. Al foil (thickness 10 μm) as a current collector was bonded to the positive electrode mixture layers on the upper and lower surfaces of the columnar electrode assembly. The positive and negative electrode tabs were joined and the electrolyte solution was injected, and then sealed in a sealed container to obtain a columnar electrode array cell (FIG. 3F). As the electrolytic solution, a mixture of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) containing 1M LiPF ₆ at a volume ratio of 3: 4: 3 was used. Using the produced cell of Experimental Example 13, the battery output was calculated. The battery output was calculated from the voltage and current value after 2 seconds when a cell charged to 4.1 V at 25 ° C. was discharged at 0.05 C.

(Experimental example 14)
A flat laminate cell was fabricated using the same members as in Experimental Example 13 described above. The cell of the flat laminate of Experimental Example 14 was produced in the order of production shown in FIG. FIG. 6 is an explanatory diagram illustrating an example of a manufacturing process of the secondary battery 30 having a stacked structure. First, a PVdF-HFP isolation membrane (electrolyte layer) having a thickness of 5 μm was prepared. On the Al foil as the current collector 36, the second electrode layer 12 containing the positive electrode mixture was formed (FIG. 6A), and this and the electrolyte layer 14 were bonded and pressed (FIG. 6B). ). Next, the negative electrode active material was artificial graphite, the binder was PVdF, each was mixed at a mass ratio of 95: 5, and dispersed in NMP as a solvent to obtain a negative electrode mixture. The negative electrode composite paste was applied to a Cu foil as a current collector 38 having a thickness of 10 μm and dried to produce the first electrode layer 15 including the negative electrode mixture supported by the current collector 38 (FIG. 6 (c)). The first electrode layer 15 formed on the current collector 38 and the electrolyte layer 14 are bonded together, and after pressing (FIG. 6D), the current collecting tabs 37 and 39 are joined to the current collectors 36 and 38. An electrolytic solution was poured into a sealed container and sealed to obtain a flat plate laminate cell (FIG. 6 (e)). Using the produced cell of Experimental Example 14, the battery output was calculated in the same manner as in Experimental Example 13.

(Results and discussion)
The structures and battery outputs (mW) of Experimental Examples 13 and 14 are shown in Table 2. Each opposed areas of the positive and negative poles of Example 13 and 14, 1.96cm ^2, a 1.25 cm ^2, the columnar electrodes arranged cell facing area was 1.54 times greater than the flat plate laminate cell. The output of this cell was 0.613 mW for the columnar electrode array cell and 0.123 mW for the flat plate laminated cell. Comparing the difference in output, the columnar electrode array cell showed an output of 4.98 times that of the flat plate cell. In an ordinary flat plate cell, when the facing area is increased 1.54 times, the output is also estimated to increase 1.54 times. On the other hand, it has been found that by making the electrode structure a columnar electrode arrangement structure, the output is increased 4.98 times simply by increasing the facing area 1.54 times. This factor was inferred to be due to, for example, the difference in the negative electrode structure. FIG. 7 is a schematic diagram of ion movement between the columnar electrode (a) and the laminated electrode (b). As shown in FIG. 7A, when a columnar electrode is used, lithium ions can diffuse from all directions from the electrolyte portion toward the center of the electrode (spherical diffusion). On the other hand, when a flat plate electrode is used, lithium ions diffuse from one direction as shown in FIG. Therefore, it was speculated that in the cell using the columnar electrode, the lithium ion diffusibility in the negative electrode was improved as compared with the cell using the plate electrode. Due to such a difference in diffusivity, it was considered that the columnar electrode aligned cell was able to achieve an output improvement that exceeded the increase in the opposing area.

  In addition, since the columnar electrode array cell has a connecting portion formed of an electrolyte, it is assumed that the single layer has flexibility as shown in FIG. 2 and can increase the degree of freedom of the cell shape. It was done.

  In addition, this indication is not limited to the Example mentioned above at all, and as long as it belongs to the technical scope of this indication, it cannot be overemphasized that it can implement with a various aspect.

DESCRIPTION OF SYMBOLS 10 Columnar electrode coupling body, 11 1st electrode, 12 2nd electrode layer, 13 Support body, 14 Electrolyte layer, 15 1st electrode layer, 20, 20B, 20C Secondary battery, 21, 21B, 21C 1st electrode, 22 Second electrode, 24 electrolyte, 25 electrode body, 26 connecting portion, 27 current collecting tab, 28 current collector, 29 current collecting tab, 36 current collector, 37 current collecting tab, 38 current collector, 39 current collecting tab.

Claims (11)

A plurality of columnar first electrodes including a first electrode active material and arranged in a predetermined direction;
A second electrode including a second electrode active material and disposed opposite to the first electrode;
An electrolyte having ion conductivity covering the first electrode and interposed between the first electrode and the second electrode;
A connecting portion configured by at least the electrolyte and connecting the first electrode and the first electrode;
Secondary battery equipped with.   2. The secondary battery according to claim 1, comprising only one layer of a columnar electrode assembly having the first electrode, the second electrode, the electrolyte, and the connecting portion.   The secondary battery according to claim 1, wherein the connecting portion has flexibility that allows the first electrode to swing. The secondary battery according to claim 1, wherein one or more of the following (1) and (2) are satisfied.
(1) When the diameter of the first electrode is D (μm) and the distance between the first electrodes is L (μm), 0.33 ≦ D / (D + L) is satisfied.
(2) When the diameter of the first electrode is D (μm) and the distance between the first electrodes is L (μm), D / (D + L) <1 is satisfied.   5. The secondary battery according to claim 1, wherein the first electrode has a diameter D (μm) in a range of 20 μm or more and 800 μm or less.   The secondary battery according to claim 1, wherein the electrolyte has a thickness t (μm) in a range of 2 μm to 15 μm. The electrolyte is formed in layers on the first electrode,
The second electrode is formed in layers on the electrolyte,
The secondary battery according to any one of claims 1 to 6, wherein an electrode main body having the first electrode, the electrolyte, and the second electrode has a structure of a columnar electrode connected body connected by the connecting portion. . The first electrode is a negative electrode including a carbonaceous material as the first electrode active material,
The secondary battery according to any one of claims 1 to 7, wherein the second electrode is a positive electrode of a composite layer formed on the surface of the electrolyte.   A plurality of columnar first electrodes including a first electrode active material are arranged in a predetermined direction with an interval for forming a connecting portion for connecting the first electrode and the first electrode, and the second electrode active material is A second electrode including an electrolyte having ion conductivity, and the electrolyte is disposed on the first electrode and between the first electrode and the second electrode so as to constitute the connecting portion, and is heated and pressed. The manufacturing method of the secondary battery including the coupling body formation process to do.   10. The method of manufacturing a secondary battery according to claim 9, wherein in the connecting body forming step, only one layer of the columnar electrode connecting body having the first electrode, the second electrode, the electrolyte, and the connecting portion is formed. The method for manufacturing a secondary battery according to claim 9 or 10, wherein in the connecting body forming step, a process that satisfies at least one of the following (1) and (2) is performed.
(1) When the diameter of the first electrode is D (μm) and the distance between the first electrodes is L (μm), 0.33 ≦ D / (D + L) is satisfied.
(2) When the diameter of the first electrode is D (μm) and the distance between the first electrodes is L (μm), D / (D + L) <1 is satisfied.

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