Secondary battery

Abstract

To provide a flexible secondary battery with a novel structure.SOLUTION: A gel electrolyte and a separator are placed between a positive electrode current collector and a negative electrode current collector where the battery reaction occurs. The gel electrolyte allows the distance between the positive electrode current collector and the negative electrode current collector to be maintained constant. Furthermore, when stacking a plurality of positive electrode current collectors and negative electrode current collectors, they are arranged such that the surfaces not coated with the negative electrode active material layer are in contact with each other. This creates a contact surface with low friction, making it easier to release stress caused by the difference between inner and outer diameters of the curve when the secondary battery is bent. This allows the distance between the positive electrode current collector and negative electrode current collector to be maintained constant, suppressing capacity loss and degradation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One aspect of the present invention relates to an article, a method, or a manufacturing method. Alternatively, the present invention relates to a process, Pertaining to a machine, manufacture, or composition of matter. One embodiment of the present invention is a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, or an electronic device. The present invention relates to a method for manufacturing a secondary battery and an electronic device.

[0002] In this specification, electronic equipment refers to any device that has a secondary battery. Electro-optical devices having a secondary battery, and information terminal devices having a secondary battery are all electronic devices. [Background technology]

[0003] In recent years, wearable devices have been actively developed. Because of its properties, it conforms to the curves of the body or curves in accordance with the movement of the body. Therefore, even in wearable devices, the display and other components are often Similarly, flexible secondary batteries are being developed.

[0004] For example, Patent Document 1 discloses a sheet that can be curved or bent in at least one axial direction. The present invention discloses a power storage device having a shape similar to that of a semiconductor device, and an electronic device incorporating the power storage device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-211262 Summary of the Invention [Problem to be solved by the invention]

[0006] In many secondary batteries, in order to increase the capacity, multiple positive electrode current collectors and multiple negative electrode current collectors are used. are piling up.

[0007] However, when a secondary battery having a plurality of positive electrode current collectors and a plurality of negative electrode current collectors is bent, When the battery is heated, the capacity and cycle characteristics of the secondary battery tend to deteriorate.

[0008] The inventors of the present invention have made efforts to investigate the cause of this deterioration in capacity and cycle characteristics, and have found several positive When a secondary battery having a positive electrode current collector and a plurality of negative electrode current collectors is bent, local It has become clear that there are cases where some areas are more strongly curved and some areas are not. FIG. 14 shows a schematic diagram of a cross section of a curved secondary battery. Less curved portions 302 are generated in various places on the negative electrode current collector 105 and the positive electrode current collector 101. The position of the part where the curvature becomes stronger is different for each current collector, so the battery reaction occurs This causes variations in the distance 311 between the positive electrode current collector 101 and the negative electrode current collector 105. The variation in distance causes the battery reaction rate to vary within the surface of the current collector, resulting in a decrease in the capacity of the secondary battery. The present inventors have discovered that this is one of the causes of deterioration.

[0009] Therefore, one aspect of the present invention provides a secondary battery with a novel structure. The present invention provides a secondary battery having a novel structure.

[0010] Another object of one embodiment of the present invention is to provide a novel power storage device, a novel electronic device, or the like. The description of these issues does not preclude the existence of other issues. An embodiment of the invention does not necessarily have to solve all of these problems. Other problems will be obvious from the description, drawings, claims, etc. It is possible to extract other issues from the specifications, drawings, claims, etc. [Means for solving the problem]

[0011] In order to achieve the above object, in one aspect of the present invention, an electrolytic The polymer containing the substance and the separator are provided. Since the polymer can be gelled, This makes it easier to maintain a constant distance between the positive electrode current collector and the negative electrode current collector.

[0012] In addition, when stacking a plurality of positive electrode current collectors and a plurality of negative electrode current collectors, for example, the active material layer of the negative electrode The positive electrode active material layer is placed on the surface of the positive electrode so that the surfaces of the positive electrode and the positive electrode are in contact with each other. The contact surfaces are arranged so that the surfaces not in contact with each other are in contact with each other. The contact surface has lower friction than the contact surface between the separator and the negative electrode active material layer. This low-friction contact surface shifts, and when the secondary battery is bent, This allows the stress caused by the difference between the inner and outer diameters of the curve to be released more easily. It suppresses the occurrence of localized areas of the body that are more curved and areas that are less curved. This makes it possible to suppress variations in the distance between the positive electrode current collector and the negative electrode current collector. [Effects of the Invention]

[0013] It is possible to provide a secondary battery with a novel structure. More specifically, a novel flexible secondary battery It is possible to provide a secondary battery having such a structure.

[0014] Alternatively, a novel power storage device, a novel electronic device, or the like can be provided. The description of an effect does not preclude the existence of other effects. However, it is not necessary for the invention to have all of these effects. Effects other than these may be included in the specification, drawings, etc. The above will be clear from the description, drawings, claims, etc. Other effects can be extracted from the description. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a diagram illustrating an example of the configuration of a secondary battery. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a secondary battery. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of a secondary battery. [Figure 4] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 5] 1A and 1B are diagrams illustrating examples of secondary batteries. [Figure 6] 1A to 1C illustrate an example of a method for manufacturing a secondary battery. [Figure 7] 1A to 1C illustrate an example of a method for manufacturing a secondary battery. [Figure 8] 1A to 1C illustrate an example of a method for manufacturing a secondary battery. [Figure 9] 1A to 1C illustrate an example of a method for manufacturing a secondary battery. [Figure 10] 1A to 1C illustrate an example of a method for manufacturing a secondary battery. [Figure 11] 1A to 1C illustrate an example of a secondary battery and a method for manufacturing the secondary battery. [Figure 12] 1A and 1B are diagrams illustrating examples of electronic devices. [Figure 13] FIG. 1 illustrates an example of an electrical device. [Figure 14] FIG. 4 is a diagram illustrating the distance between a positive electrode current collector and a negative electrode current collector. [Figure 15] FIG. 2 is a diagram illustrating a method for measuring a static friction coefficient. [Figure 16] Measurement results of static friction coefficient. [Figure 17] X-ray CT image and charge / discharge characteristics of a secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following description, and various modifications in form and details are possible by those skilled in the art. Furthermore, the present invention should not be construed as being limited to the description of the following embodiments. It is not something that can be done.

[0017] "Electrically connected" means that the connection is made via "something that has some kind of electrical effect." Here, "something that has some kind of electrical effect" means an electrical signal between connected objects. There are no particular restrictions as long as it allows the exchange of numbers.

[0018] The position, size, range, etc. of each component shown in the drawings are not necessarily the actual size for ease of understanding. Therefore, the disclosed invention may not necessarily represent the position, size, range, etc. Furthermore, the present invention is not limited to the position, size, range, etc. disclosed in the drawings, etc.

[0019] Ordinal numbers such as "first," "second," and "third" are used to avoid confusion of components. is.

[0020] (Embodiment 1) In this embodiment, an example of a configuration of a secondary battery according to one embodiment of the present invention will be described with reference to FIGS. 1 and 3. This article explains:

[0021] [1. Typical configuration] The secondary battery 100 shown in FIG. 1(A) includes a positive electrode current collector 101, a negative electrode current collector 105, a separator The positive electrode current collector 101 has a positive electrode active material layer 102 on one surface and a positive electrode active material layer 103 on the other surface. The negative electrode current collector 105 does not have a positive electrode active material layer on one side. The secondary battery 100 has a positive electrode current collector 10 and no negative electrode active material layer on the other surface. A gel electrolyte 104 is provided between one surface of the negative electrode current collector 105 and one surface of the negative electrode current collector 105 .

[0022] The gel electrolyte 104 includes a polymer, an electrolyte, and a solvent. Since the polymer can be made into a gel, when the positive electrode current collector 101 and the negative electrode current collector 105 are bonded together, This makes it easier to keep the distance between the positive electrode current collector 101 and the negative electrode current collector 105 constant. The speed of the battery reaction is prevented from varying within the surface of the current collector, and the capacity of the secondary battery 100 is prevented from decreasing. This can suppress deterioration.

[0023] The polymer contained in the gel electrolyte 104 may be, for example, a polyethylene oxide-based polymer, a polyaniline-based polymer, or a polyethylene oxide-based polymer. Crylonitrile, polyvinylidene fluoride, polyacrylate, polymethacrylate In this specification and the like, for example, polyvinylidene fluoride polymers can be used. The term "vinylidene fluoride polymer" refers to a polymer containing polyvinylidene fluoride. Includes ethylene-hexafluoropropylene copolymers, etc.

[0024] In addition, the above polymers can be quantitatively analyzed using FT-IR (Fourier transform infrared spectrophotometer) and other instruments. For example, polyvinylidene fluoride polymers can be analyzed by FT-IR. The spectrum shows absorption indicating C—F bonds. The FT-IR spectrum shows absorption indicative of a C≡N bond.

[0025] The gel electrolyte 104 is an electrolyte that allows carrier ions to move and A material containing lithium ions, which are ions, is used. A typical example of an electrolyte is LiP F6, LiClO4, LiAsF6, LiBF4, LiCF3SO3, Li(CF3SO 2) Lithium salts include 2N, Li(C2F5SO2)2N, Li(SO2F)2N, etc. These electrolytes may be used alone or in any combination and ratio of two or more. It may be used.

[0026] The solvent of the gel electrolyte 104 is a material that allows carrier ions to move. The solvent for the solution is preferably an aprotic organic solvent. Representative examples of aprotic organic solvents are: Examples include ethylene carbonate (EC), propylene carbonate, and dimethyl carbonate. diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-benzyl These include tyrolactone, acetonitrile, dimethoxyethane, and tetrahydrofuran. One or more of these can be used. In addition, a polymer that can be gelled as a solvent for the electrolyte can be used. By using a polymer material or adding a polymer material to the electrolyte for gelation, leakage resistance, etc. In addition, it is possible to make the secondary battery thinner and lighter. Representative examples of polymeric materials include silicone gel, acrylic gel, and acrylonitrile gel. , polyethylene oxide gel, polypropylene oxide gel, fluorine-based polymer In addition, ionic liquids (normally occurring liquids) that are flame-retardant and non-volatile are used as solvents for electrolytes. By using one or more high-temperature molten salts, it is possible to prevent internal short circuits in secondary batteries and internal Even if the internal temperature rises, the secondary battery can be prevented from exploding or catching fire. Ionic liquids are salts in a fluid state and have high ion mobility (conductivity). It contains a thione and an anion. Ionic liquids include ethylmethylimidazolium (EMI) ) cation, or N-methyl-N-propylpiperidinium (PP1 3) Ionic liquids containing cations.

[0027] The positive electrode current collector 101, the positive electrode active material layer 102, the separator 103, the gel electrolyte 104, The negative electrode current collector 105 and the negative electrode active material layer 106 constitute one unit. 0 has multiple units.

[0028] 1(B) and 1(C) show an example of a secondary battery 100 in which three units are stacked. FIG. 1(B) is a perspective view of the secondary battery 100, and FIG. 1(C) is a view of the secondary battery as seen from the direction of the arrow in FIG. 1(B). 1 is a side view of a battery 100. For clarity of explanation, the positive electrode current collector 101 and the negative electrode current collector 102 are shown. The positive electrode current collector 101 is connected to the positive electrode 105 and the gel electrolyte 104. The other surface of the negative electrode current collector 105 that does not have an electrode active material layer is The positive electrode current collector 10 is disposed so that the other surfaces thereof face each other. a contact surface 201 between the other surfaces of the negative electrode current collectors 101 and 105; 5, a metal-to-metal contact surface can be created.

[0029] The contact surface 201 and the contact surface 205, which are the contact surfaces between the metals, are the positive electrode active material layer 102 and the separator. and the contact surface between the negative electrode active material layer 106 and the separator 103. The other surfaces of the positive electrode current collectors 101 or the negative electrode current collectors 102 can be made to have a small contact area. The units are stacked so that the other surfaces of the bodies 105 face each other to form the secondary battery 100. As a result, when the secondary battery 100 is bent, as shown in FIG. 1(D), the small friction The contact surface is displaced. This makes it easier to release stress caused by the difference between the inner and outer diameters of the curve. This allows for localized areas of the current collector that are more strongly curved and areas that are not so strongly curved. The occurrence of unevenness in the distance between the positive electrode current collector 101 and the negative electrode current collector 105 is suppressed. can be suppressed.

[0030] For the above reasons, the other surfaces of the positive electrode current collectors 101 or the other surfaces of the negative electrode current collectors 105 are Between the two surfaces, there is an element that increases friction, such as a polymer contained in the gel electrolyte 104. It is preferable not to have it.

[0031] The friction between the other surfaces of the positive electrode current collectors 101 and the other surfaces of the negative electrode current collectors 105 The smaller the friction, the easier it is to release the stress caused by the difference between the inner and outer diameters of the curve. If excessive surface treatment is performed on the other side of the current collector to reduce the size, the number of processes will increase. In addition, the other surfaces of the positive electrode current collector 101 and the negative electrode current collector 102 are not necessarily aligned with each other. The friction between the other surfaces of the positive electrode current collector 101 and the other surfaces of the positive electrode current collector 105 does not have to be small. If the friction between the other surfaces of the negative electrode current collector 105 is small, the bending The stress caused by the difference between the inner diameter and the outer diameter can be sufficiently released.

[0032] Therefore, more specifically, between the other surfaces of the positive electrode current collectors 101 or between the other surfaces of the negative electrode current collectors 10 The coefficient of static friction between the other surfaces of the 5 is 0.01 or more and 0.80 or less, more preferably 0. It is preferable that the ratio is 20 or more and 0.65 or less, and more preferably 0.57 or more and 0.59 or less. If the coefficient of static friction is within the range of It is possible.

[0033] The coefficient of static friction in this specification can be determined as follows: Place the sample to be measured on a flat glass plate. The object is sandwiched between the opposing materials. A flat plate and a weight are placed on top of it. The opposing materials are fixed. A load tester is attached to the material to be slid, and the load tester is pulled horizontally at approximately 1 mm / sec. The maximum friction force is measured until the sliding material moves 1 cm, and this measurement is taken as the maximum static friction. The coefficient of static friction is calculated from the maximum static friction force and the load of the flat plate and weight.

[0034] [2. Modifications] In FIG. 1(A), the separator 103 is sandwiched between the positive electrode current collector 101 and the negative electrode current collector 105. Although an example in which the separator 103 exists only in the region is shown, one embodiment of the present invention is not limited to this. However, the positive electrode current collector 101 or the negative electrode current collector 105 may be wrapped in a bag shape.

[0035] In the secondary battery 100 shown in FIG. 2(A), a separator 103 is disposed between a positive electrode current collector 101 and a positive electrode active material. The positive electrode current collector 101 is provided so as to enclose the material layer 102 in a bag-like shape. The surfaces do not come into direct contact, but instead there is a contact surface 203 between the separators 103 .

[0036] Even in this case, if the friction between the contact surfaces 205 of the other surfaces of the negative electrode current collectors 105 is small, It is possible to fully release the stress caused by the difference between the inner and outer diameters when bending.

[0037] In the secondary battery 100 shown in FIG. 2(B), the separator 103 is connected to the negative electrode current collector 105 and the negative electrode current collector 106. The negative electrode current collector 105 and the negative electrode active material layer 106 are wrapped in a bag-like shape. The two surfaces do not come into direct contact with each other, but instead have contact surfaces 203 between the separators 103 .

[0038] Even in this case, if the friction between the contact surfaces 201 of the other surfaces of the positive electrode current collectors 101 is small, It is possible to fully release the stress caused by the difference between the inner and outer diameters when bending.

[0039] 1 and 2, one unit includes a positive electrode current collector 101, a positive electrode active material layer 102, a separator 1. An example in which one plate 103, one negative electrode current collector 105, and one negative electrode active material layer 106 are provided. However, one embodiment of the present invention is not limited to this. The unit has a plurality of positive electrode current collectors 101 and a plurality of positive electrode current collectors 102 within a range where the force can be sufficiently dissipated. A positive electrode active material layer 102, a plurality of separators 103, a plurality of negative electrode current collectors 105, and a plurality of negative The electrode active material layer 106 may be included.

[0040] In the secondary battery 100 shown in FIG. 3(A), one unit has a positive electrode active material layer 102 on both sides. The positive electrode current collector 101 has a negative electrode active material layer 106 on one side and a negative electrode active material layer 107 on the other side. This is an example in which two negative electrode current collectors 105 without a barrier and two separators 103 are provided.

[0041] In the secondary battery 100 unit of FIG. 3(A), the other surface of the negative electrode current collector 105 is the outermost surface. A positive electrode current collector 102 having a positive electrode active material layer 102 on both sides is positioned between two negative electrode current collectors 105. The units are arranged such that the other surfaces of the negative electrode current collectors 105 face each other. In FIG. 3(A), one unit has two separators 103. However, the present invention is not limited to this example, and a single sheet such as that shown in FIG. 2 encases the positive electrode current collector 101 in a bag-like shape. The separator may be:

[0042] In addition, another example of the secondary battery 100 shown in FIG. 3(B) is a secondary battery in which one unit has a A positive electrode current collector 101 has a positive electrode active material layer 102 on one side and no positive electrode active material layer on the other side. a negative electrode current collector 105 having a negative electrode active material layer 106 on one side, and a positive electrode current collector 106 having a positive electrode active material layer 102 on both sides. A negative electrode current collector 101 has a negative electrode active material layer 106 on one side and no negative electrode active material layer on the other side. The negative electrode current collector 105 has a positive electrode active material layer 102 on one side and a negative electrode current collector 105 on the other side in the above order. The positive electrode current collector 101 having no positive electrode active material layer is arranged so that the other surface becomes the outermost surface of the unit. Similarly, a negative electrode active material layer 106 is disposed on one side and a negative electrode active material layer is disposed on the other side. The negative electrode current collector 105 that does not have a surface is arranged so that the other surface is the outermost surface of the unit. A separator 103 was placed between each of the three positive electrode active material layers 102 and the three negative electrode active material layers 106. It has one.

[0043] Even in the secondary battery 100 having the configuration shown in FIGS. 3(A) and 3(B), the friction between metals is small. Therefore, the positive electrode current collector 101 and the negative electrode current collector 105 can be formed with a smooth contact surface 205. This can suppress the variation in the distance between the

[0044] 1 and 2 show a secondary battery having three units, and FIG. 3 shows a secondary battery having two units. However, this is an excerpt for clarity of the diagram, and in reality, there are three or more units. It is preferable to use a secondary battery 100 having a plurality of units stacked together. The capacity of the pond 100 can be increased.

[0045] Note that one embodiment of the present invention can be applied not only to secondary batteries but also to various power storage devices. For example, examples of the power storage device include a battery, a primary battery, a secondary battery, a lithium ion battery, and the like. Lithium-ion secondary battery, lithium-air battery, solid-state battery, lead-acid battery, lithium-ion polymer secondary battery , nickel-metal hydride battery, nickel-cadmium battery, nickel-iron battery, nickel Other examples of storage batteries include zinc-oxide batteries and silver oxide-zinc batteries. For example, a negative electrode according to one embodiment of the present invention and an electric double layer and a positive electrode to form a capacitor such as a lithium ion capacitor. It is also possible.

[0046] Note that one embodiment of the present invention has been described in this embodiment. However, the present invention is not limited to these. For example, in one embodiment of the present invention, the gel electrolyte contains a polymer. However, one aspect of the present invention is not limited to this. In one aspect of the present invention, the electrolyte may contain a material other than a polymer. In some cases, or depending on the situation, one aspect of the present invention is that the electrolyte has a polymer. For example, as one embodiment of the present invention, an example in which the secondary battery is curved is shown. However, one aspect of the present invention is not limited thereto. Therefore, in one embodiment of the present invention, the power storage device may be deformed as needed by bending, stretching, or the like. For example, in some cases or situations, In accordance with this, in one embodiment of the present invention, the power storage device does not need to be curved.

[0047] (Embodiment 2) In this embodiment, a specific structure and materials of a secondary battery according to one embodiment of the present invention will be described. 4 and 5. In this embodiment, either the positive electrode or the negative electrode is a bag-shaped An example of a separator covered with

[0048] 4 is a perspective view showing the appearance of the secondary battery 100. FIG. 5(A) shows one of A1-A2 in FIG. 5B is a cross-sectional view of the portion indicated by the dashed line B1-B2 in FIG. FIG. 1 is a cross-sectional view of the area indicated by .

[0049] The secondary battery 100 according to one embodiment of the present invention includes a positive electrode 104 covered with a separator 103 in an exterior body 107. The battery has a positive electrode 111, a negative electrode 115, and a gel electrolyte 104. In FIG. 5, three units are shown. The positive electrode 111 is electrically connected to a positive electrode lead 121. The negative electrode 115 is electrically connected to the negative electrode lead 125. The positive and negative electrode leads 125 are also called lead electrodes or lead terminals. 1 and a part of the negative electrode lead 125 are disposed outside the exterior body. Charging and discharging occurs through positive lead 121 and negative lead 125 .

[0050] Note that although the positive electrode 111 is covered with the separator 103 in FIG. 5, in one embodiment of the present invention, For example, the positive electrode 111 does not have to be covered with the separator 103. For example, instead of the positive electrode 111, the negative electrode 115 may be covered with the separator 103. stomach.

[0051] [1. Positive electrode] The positive electrode 111 is composed of a positive electrode current collector 101 and a positive electrode active material layer 10 formed on the positive electrode current collector 101. 2. In FIG. 5, one surface of a sheet-shaped (or strip-shaped) positive electrode current collector 101 is 1 shows an example in which the positive electrode active material layer 102 is provided on the secondary Depending on the unit configuration of the battery 100, the positive electrode active material layer 102 may be formed on both sides of the positive electrode current collector 101. By providing the positive electrode active material layer 102 on both sides of the positive electrode current collector 101, the secondary The capacity of the pond 100 can be increased.

[0052] The positive electrode current collector 101 is made of metal such as stainless steel, gold, platinum, aluminum, titanium, etc. It is possible to use materials that are highly conductive and do not undergo significant chemical changes, such as these alloys. In addition, the heat resistance of silicon, titanium, neodymium, scandium, molybdenum, etc. can be improved. Aluminum alloys containing elements that increase the reaction rate can be used. Alternatively, the metal element may be formed of a metal element that reacts with silicon to form a silicide. The metal elements forming the , tantalum, chromium, molybdenum, tungsten, cobalt, nickel, etc. The electric body 101 may be in the form of a foil, a plate (sheet), a mesh, a punched metal, an expanded metal, or the like. The positive electrode current collector 101 may have a thickness of 5 μm to 30 μm. It is also preferable to use graphite or the like on the surface of the positive electrode current collector 101. An undercoat layer may be provided.

[0053] The positive electrode active material layer 102 contains a positive electrode active material and a binder (binder) for increasing the adhesion of the positive electrode active material. The positive electrode active material layer 102 may contain an indium ion, a conductive additive for increasing the conductivity of the positive electrode active material layer 102, or the like.

[0054] The positive electrode active material used in the positive electrode active material layer 102 may have an olivine type crystal structure, a layered rock salt type There are composite oxides with a crystalline structure or a spinel-type crystalline structure. , e.g., LiFeO2, LiCoO2, LiNiO2, LiMn2O4, V2O5, C Compounds such as r2O5 and MnO2 are used.

[0055] In particular, LiCoO2 has a large capacity and is more stable in the air than LiNiO2. and is preferable because it has advantages such as being thermally stable compared to LiNiO2.

[0056] In addition, lithium-containing materials with a spinel-type crystal structure containing manganese, such as LiMn2O4, The material contains a small amount of lithium nickel oxide (LiNiO2 or LiNi 1-x M X O2 (M = Co, Mixing aluminum (Al, etc.) is preferable because it can improve the characteristics of the secondary battery using it. .

[0057] Alternatively, a composite material (general formula LiMPO4, where M is Fe(II), Mn(II), Co(II) Representative examples of the general formula LiMPO4 include: Examples include LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, and LiFe a Ni b PO4, LiFe a Co b PO4, LiFe a Mn b PO4, LiNi aCo b PO4, LiNi a Mn b PO4 (a + b is less than or equal to 1, 0 < a < 1, 0 < b < 1), LiF e c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn e PO 4 (c + d + e is less than or equal to 1, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g C o h Mn i PO4 (f + g + h + i is less than or equal to 1, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 <i < 1), etc. Lithium compounds can be used as materials.

[0058] In particular, LiFePO4 satisfies the requirements for a cathode active material, such as safety, stability, high capacity density, and the presence of lithium ions that can be extracted during initial oxidation (charging), in a well - balanced manner. Therefore, it is preferable.

[0059] Or, composite materials such as the general formula Li (2-j) MSiO4 (M is one or more of Fe(II), Mn(II), Co( II), Ni(II), 0 ≤ j ≤ 2) can be used. As representative examples of the general formula Li (2-j) MSiO4, there are Li (2-j) FeSiO4, Li (2 <000003o>NiSiO4, Li (2-j) CoSiO4, Li (2-j) MnSiO4, Li (2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co ll SiO4, Li (2-j ) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k Mn l SiO4 (k + l is 1 or less, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m N i n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (m + n + q is 1 or less, 0 < m < 1, 0 < n < 1, 0 < q < 1) , Li (2-j) Fe r Ni s Co t Mn u SiO4 (r + s + t + u is 1 or less, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1), etc. Lithium compounds can be used as materials and so on.

[0060] Also, as the positive electrode active material, A x M2(XO4)3 (A = Li, Na, Mg, M = Fe, M n, Ti, V, Nb, X = S, P, Mo, W, As, Si) represented by the general formula of NASICON type compounds can be used. NASICON type compounds include Fe2(MnO4)3, F e2(SO4)3, Li3Fe2(PO4)3, etc. Also, as the positive electrode active material, Li 2MPO4F, Li2MP2O7, Li5MO4 (M = Fe, Mn) represented by the general formula Compounds, perovskite-type fluorides such as NaFeF3 and FeF3, TiS2, MoS2, etc. Metal chalcogenides (sulfides, selenides, tellurides), inverse spinels such as LiMVO4 Oxides with a vanadium-type crystal structure (V2O5, V6O 13 , LiV3 O8, etc.), manganese oxides, organic sulfur compounds, and other materials can be used.

[0061] In addition, the carrier ions are alkali metal ions other than lithium ions, alkaline earth metal ions, etc. In the case of metal ions, alkali metals (e.g., sodium) are used as the positive electrode active material instead of lithium. alkaline earth metals (e.g., calcium, strontium, barium, etc.), For example, NaFeO2 or Na2 / 3 [Fe 1 / 2 Mn 1 / 2 ]O2 as a positive electrode active material. It can be used.

[0062] Furthermore, a combination of the above materials may be used as the positive electrode active material. A solid solution of a combination of these materials can be used as the positive electrode active material. Co 1 / 3 Mn 1 / 3 Ni 1 / 3 A solid solution of O2 and Li2MnO3 was used as the positive electrode active material. It is possible.

[0063] Although not shown, a conductive material such as a carbon layer may be provided on the surface of the positive electrode active material layer 102. The conductivity of the electrode can be improved by providing a conductive material such as a carbon layer. For example, the carbon layer covering the positive electrode active material layer 102 may be formed by adding glucose or the like when baking the positive electrode active material. It can be formed by mixing carbohydrates.

[0064] The average particle size of the primary particles of the granular positive electrode active material layer 102 is 50 nm or more and 100 μm or less. It is recommended to use

[0065] Conductive additives include acetylene black (AB), graphite particles, and carbon Nanotubes, graphene, fullerenes, etc. can be used.

[0066] The conductive additive can form an electron conductive network in the positive electrode 111. The auxiliary agent can maintain the electrical conduction path between the positive electrode active material layers 102. By adding a conductive additive to the active material layer 102, a positive electrode active material having high electronic conductivity can be obtained. Layer 102 can be realized.

[0067] In addition to the typical polyvinylidene fluoride (PVDF), polyimide, Polytetrafluoroethylene, polyvinyl chloride, ethylene propylene diene polymer Styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber, poly Vinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose, etc. This can be done.

[0068] The content of the binder relative to the total amount of the positive electrode active material layer 102 is 1 wt % or more and 10 wt % or less. It is preferable that the content is 2 wt% or more and 8 wt% or less, more preferable that the content is 3 wt% or more and 5 wt% or less. In addition, the content of the conductive additive relative to the total amount of the positive electrode active material layer 102 is preferably 1 wt % or more. The content is preferably from 1 to 10 wt%, more preferably from 1 to 5 wt%.

[0069] When the positive electrode active material layer 102 is formed by a coating method, the positive electrode active material, the binder, and the conductive additive are mixed. The positive electrode paste (slurry) is prepared by mixing the above, and is then applied onto the positive electrode current collector 101 and dried. That's fine.

[0070] [2. Negative electrode] The negative electrode 115 is composed of a negative electrode current collector 105 and a negative electrode active material layer 10 formed on the negative electrode current collector 105. 5, one surface of a sheet-shaped (or strip-shaped) negative electrode current collector 105 is 1 shows an example in which the negative electrode active material layer 106 is provided on the secondary Depending on the unit configuration of the battery 100, the negative electrode active material layer 106 may be formed on both sides of the negative electrode current collector 105. By providing the negative electrode active material layers 106 on both sides of the negative electrode current collector 105, the secondary The capacity of the pond 100 can be increased.

[0071] The negative electrode current collector 105 is made of metals such as stainless steel, gold, platinum, iron, copper, titanium, and the like, and Use materials such as alloys that are highly conductive and do not alloy with carrier ions such as lithium. In addition, heat-resistant materials such as silicon, titanium, neodymium, scandium, and molybdenum can be used. An aluminum alloy containing an element that improves the resistance can be used. 5 is a foil, plate (sheet), mesh, punched metal, expanded metal, etc. The negative electrode current collector 105 has a thickness of 5 μm or more and 30 μm or less. It is also preferable to use a material that is coated with graphite or the like on the surface of the negative electrode current collector 105. A dark coat layer may be provided.

[0072] The negative electrode active material layer 106 contains, in addition to the negative electrode active material, a binder (binder) for increasing the adhesion of the negative electrode active material. The negative electrode active material layer 106 may contain an indium ion, a conductive additive for increasing the conductivity of the negative electrode active material layer 106, or the like.

[0073] The negative electrode active material is a material that can dissolve and deposit lithium or can insert and extract lithium ions. The material of the negative electrode active material layer 106 is not particularly limited, and may be lithium metal or titanium. In addition to lithium oxide, examples include carbon-based materials and alloy-based materials that are common in the field of electricity storage.

[0074] Lithium metal has a low oxidation-reduction potential (-3.045 V vs. the standard hydrogen electrode) and is lightweight and and high specific capacity per volume (3860mAh / g and 2062mAh / cm, respectively) 3 ) and is therefore preferable.

[0075] Carbon materials include graphite, easily graphitizable carbon (soft carbon), and non-graphitizable carbon (hard carbon). Examples of such materials include graphene, carbon black, graphene nanotubes, graphene nanofibers, and graphene nanofibers.

[0076] Graphite includes mesocarbon microbeads (MCMB), coke-based artificial graphite, and pitch. Examples of such graphite include artificial graphite such as spheroidized artificial graphite, and natural graphite such as spheroidized natural graphite.

[0077] When lithium ions are inserted between the layers of graphite (when lithium-graphite intercalation compounds are formed), ), and shows a potential as noble as that of lithium metal (0.1 to 0.3 V vs. Li / Li + This allows the lithium-ion battery to exhibit a high operating voltage. Lead has a relatively high capacity per unit volume, small volume expansion, and is inexpensive. It is preferred because it has advantages such as higher safety compared to the metal.

[0078] As a negative electrode active material, it is possible to carry out charge-discharge reactions by alloying and dealloying reactions with lithium. A suitable alloy material or oxide can also be used. In some cases, the alloy material may be, for example, Mg, Ca, Al, Si, Ge, Sn, Pb, Material containing at least one of Sb, Bi, Ag, Au, Zn, Cd, Hg, and In, etc. Such elements have a large capacity compared to carbon, and silicon in particular has a theoretical capacity Therefore, it is possible to use silicon as the negative electrode active material. As alloy materials using such elements, for example, Mg2Si, Mg2 Ge, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, C u6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La 3Co2Sn7, CoSb3, InSb, SbSn, etc.

[0079] In addition, the negative electrode active material is SiO, SnO, SnO2, titanium oxide (TiO2), lithium Li4Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), acid Niobium oxide (Nb2O5), tungsten oxide (WO2), molybdenum oxide (MoO2), etc. The oxides of the following can be used.

[0080] In addition, the negative electrode active material is a composite nitride of lithium and transition metals, which has a Li3N structure. Li 3-x M x N (M=Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 N has a large charge / discharge capacity (900mAh / g, 1890mAh / cm 3 ) indicates preferable.

[0081] When a composite nitride of lithium and a transition metal is used, the negative electrode active material contains lithium ions, The positive electrode active material is a combination of materials such as V2O5 and Cr3O8 that do not contain lithium ions. It is preferable that a material containing lithium ions is used as the positive electrode active material. By first removing the lithium ions contained in the positive electrode active material, As the nitride, a complex nitride of lithium and a transition metal can be used.

[0082] In addition, a material that undergoes a conversion reaction can also be used as the negative electrode active material. , cobalt oxide (CoO), nickel oxide (NiO), iron oxide (FeO), etc. A transition metal oxide that does not undergo an alloying reaction with the negative electrode active material may be used. Further materials that undergo a reaction include Fe2O3, CuO, Cu2O, RuO2, and Cr2O Third order oxide, CoS 0.89 , NiS, CuS and other sulfides, Zn3N2, Cu3N, G Nitrides such as e3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3 The above fluorides have high electrode potentials, so they are often used as positive electrode active materials. It may be used.

[0083] When the negative electrode active material layer 106 is formed by a coating method, the negative electrode active material and the binder are mixed together to form the negative electrode active material layer 106. Anode paste (slurry) may be prepared, applied to the negative electrode current collector 105, and then dried. A conductive additive may be added to the negative electrode paste.

[0084] Graphene may be formed on the surface of the negative electrode active material layer 106. When silicon is used, the volume due to the absorption and release of carrier ions during the charge and discharge cycle is Since the change in the negative electrode current collector 105 is large, the adhesion between the negative electrode active material layer 106 and the negative electrode current collector 105 is reduced, and the charge / discharge Therefore, the surface of the negative electrode active material layer 106 containing silicon is When graphene is formed on silicon, the volume of silicon changes during the charge-discharge cycle. In addition, it is possible to suppress a decrease in the adhesion between the negative electrode current collector 105 and the negative electrode active material layer 106. This is preferable because it reduces deterioration of the pond characteristics.

[0085] In addition, a coating of an oxide or the like may be formed on the surface of the negative electrode active material layer 106. The film formed by the decomposition of the electrolyte releases the charge consumed during its formation. In contrast, a film of oxide or the like is formed on the negative electrode active material in advance, and irreversible capacity is formed. By providing it on the surface of the layer 106, it is possible to suppress or prevent the occurrence of irreversible capacity. .

[0086] The coating that coats the negative electrode active material layer 106 may contain niobium, titanium, vanadium, tungsten, or the like. aluminum, tungsten, zirconium, molybdenum, hafnium, chromium, aluminum or or silicon oxide film, or a film containing one of these elements and lithium Such a coating can be formed on the negative electrode by the decomposition products of conventional electrolytes. This film is sufficiently dense compared to the coating formed on the surface.

[0087] For example, niobium oxide (Nb2O5) has an electrical conductivity of 10 -9 Low S / cm and high insulation Therefore, the niobium oxide film prevents the electrochemical decomposition reaction between the negative electrode active material and the electrolyte. On the other hand, the lithium diffusion coefficient of niobium oxide is 10-9 cm 2 / sec, which is high It has lithium ion conductivity, which allows lithium ions to pass through. Silicon oxide or aluminum oxide may also be used.

[0088] The film that covers the negative electrode active material layer 106 can be formed by, for example, a sol-gel method. The sol-gel method is a method in which a solution of metal alkoxides and metal salts is subjected to hydrolysis and polymerization. This method involves creating a gel that loses fluidity through a condensation reaction, and then baking this gel to form a thin film. The sol-gel method is a method for forming thin films from a liquid phase, so the raw materials are mixed homogeneously at the molecular level. For this reason, the raw material for the metal oxide film at the solvent stage can be mixed with a negative electrode active material such as graphite. By adding the active material, it is possible to easily disperse the active material in the gel. A coating can be formed on the surface of the electrode active material layer 106. By using the coating, It can prevent a decrease in body volume.

[0089] [3. Separator] The separator 103 may be made of a material such as cellulose or polypropylene (PP). , polyethylene (PE), polybutene, nylon, polyester, polysulfone, polya Uses porous insulators such as chlorine nitrile, polyvinylidene fluoride, and tetrafluoroethylene. In addition, nonwoven fabrics such as glass fiber and composites of glass fiber and polymer fiber can be used. A diaphragm may also be used.

[0090] [4. Electrolyte] The electrolyte solution used as the material of the gel electrolyte 104 in the secondary battery 100 is You can refer to the description.

[0091] [5. Exterior body] There are various types of secondary battery structures. In this embodiment, the outer casing 107 is formed The film for forming the exterior body 107 is a metal film (aluminum). aluminum, stainless steel, nickel steel, etc.), plastic film made of organic materials, Hybrid materials that contain organic materials (such as organic resins and fibers) and inorganic materials (such as ceramics) Material film, carbon-containing inorganic film (carbon film, graphite film, etc.) A single layer film selected from the above or a laminated film made up of a plurality of these metal films is used. is easy to emboss, and when recesses or protrusions are formed by embossing, Since the surface area of ​​the exterior body 107 that comes into contact with the heat source increases, the heat dissipation effect is excellent.

[0092] In addition, when the shape of the secondary battery 100 is changed by applying an external force, the outside of the secondary battery 100 When external bending stress is applied to the exterior body 107, a part of the exterior body 107 is deformed or partially destroyed. By forming a recess or a protrusion on the exterior body 107, The strain caused by the applied stress can be alleviated. The reliability of the strain can be improved. It is a measure of deformation that indicates the displacement of a material point within an object. This keeps the effects of distortion caused by applying force from outside the storage battery within an acceptable range. Therefore, a highly reliable electricity storage unit can be provided.

[0093] This embodiment mode can be implemented in appropriate combination with other embodiment modes and examples. be.

[0094] (Embodiment 3) In this embodiment, an example of a method for manufacturing the secondary battery 100 will be described with reference to FIGS. explain.

[0095] [1. Cover the positive electrode with a separator] First, a positive electrode 111 having a positive electrode active material layer 102 formed thereon is placed on a separator 103 (see FIG. 6(A). In this embodiment, the positive electrode active material layer 10 is formed only on one surface of the positive electrode current collector. 6(A) shows an example in which the positive electrode 111 has a positive electrode active material layer 10 on the surface shown in FIG. 2 on one side and a positive electrode active material layer 102 on the other side. 6(A) (see FIG. 6(B)), and the separator 103 is folded along the dotted line. 11 is sandwiched between the two pieces (see Figure 6(C)).

[0096] Next, the outer peripheral portion of the separator 103 on the outside of the positive electrode 111 is joined to form a bag-shaped separator. The outer periphery of the separator 103 is bonded with an adhesive. Alternatively, ultrasonic welding or heat fusion may be used.

[0097] In this embodiment, polypropylene is used as the separator 103. The outer periphery of the wire is bonded by heating. The bonded portion 103a is shown in FIG. 6(D). The positive electrode 111 can be covered with a separator 103. The separator 103 is made of a positive electrode active material. It is sufficient to form the layer 102 so as to cover it, and it is not necessary to cover the entire positive electrode 111 .

[0098] Although the separator 103 is bent in FIG. 6, one embodiment of the present invention is not limited to this. For example, the positive electrode 111 may be sandwiched between two separators. The joint 103a may be formed so as to surround most of the four sides.

[0099] The outer periphery of the separator 103 may be joined with a gap at a fixed interval. Alternatively, the bonding may be performed in a dotted pattern at regular intervals.

[0100] Alternatively, joining may be performed on only one side of the outer periphery. Alternatively, joining may be performed on only two sides of the outer periphery. Alternatively, joining may be performed on the four sides of the outer periphery. The edges can be made even.

[0101] 6 and the like, the case where the positive electrode 111 is covered with the separator 103 is described. However, one embodiment of the present invention is not limited thereto. For example, the positive electrode 111 may be formed by For example, instead of the positive electrode 111, the negative electrode 115 may be covered by the separator 112. The insulating film 103 may be covered with the insulating film 103.

[0102] [2. Join one side of the exterior body] Next, fold the film used for the exterior packaging at the part indicated by the dotted line (see Figure 7(A)) and The overlapping sides are joined by thermocompression. The joined portion is shown as a joint 107a.

[0103] [3. Stack the positive and negative electrodes to create a unit] Next, the positive electrode 111 and the negative electrode 115 that constitute one unit are stacked together, and the exterior body 107 is (See FIG. 7(C)). At this time, as explained in the first embodiment, In this example, the positive electrode active material layer 102 and the negative electrode active material layer 106 are arranged opposite to each other with the separator 103 interposed therebetween. The outermost part of the unit is a positive electrode current collector 101 that does not have a positive electrode active material. The negative electrode current collector 105 is placed so that the negative electrode active material is not present on the negative electrode surface or the negative electrode active material is not present on the negative electrode surface. In this embodiment, one unit includes a positive electrode current collector 101, a positive electrode active material layer 102, and a separator 10. 3. An example having one negative electrode current collector 105 and one negative electrode active material layer 106 is shown. vinegar.

[0104] Next, a side of the exterior body 107 other than the side joined above is joined by thermocompression bonding. The portion where one side of the exterior body 107 is joined to the outer body 18(A) by thermocompression is Like one side of 07, it is shown as joint 107a.

[0105] Next, the gel electrolyte is poured from the unsealed side 107b of the exterior body 107 shown in FIG. 8(A). The electrolyte 104a, which is the material of the electrolyte 104, is poured into the area covered with the outer casing 107. 4a contains a polymer material, an electrolyte, and a solvent, and is then vacuumed, heated, and pressurized. While performing the above, the side 107b of the exterior body 107 is sealed. The vacuum sealer is used to seal the container in an oxygen-free environment. It is recommended to use a sealer or similar device. It is also possible to clamp the seal between two heatable bars of the sealer. The conditions for each are, for example, a vacuum of 60 kPa. The heating conditions can be 190°C and the pressure conditions can be 0.1 MPa for 3 seconds.

[0106] Then, the polymer material contained in the electrolytic solution 104a is sufficiently gelled to form the gel electrolyte 104 At this time, pressure may be applied to the unit from above the exterior body 107. Air bubbles that may have been mixed in when the liquid 104a was poured can be removed from between the positive and negative electrodes.

[0107] [4. Remove the unit and remove the unnecessary gel electrolyte] Next, the exterior body 107 is cut open and the unit is taken out (see FIG. 8(B)). In the gel electrolysis chamber, the positive electrode active material layer 102 and the negative electrode active material layer 106 are placed opposite each other. The positive electrode current collector 101 and the negative electrode current collector 105 are bonded together by a substrate 104. While the gel electrolyte 104 that bonds the electrode current collector 101 and the negative electrode current collector 105 is held , remove the gel electrolyte 104 attached to the outer surface of the unit. By removing the attached gel electrolyte 104, the positive electrode current collector 101 is free of the positive electrode active material. To reduce friction between the surfaces or between the surfaces of the negative electrode current collector 105 that do not have the negative electrode active material. can be done.

[0108] There is no particular limitation on the method for removing unnecessary portions of the gel electrolyte 104. For example, The surface of the negative electrode current collector 101 that does not have a positive electrode active material or the surface of the negative electrode current collector 105 that does not have a negative electrode active material A sheet is attached in advance, and the sheet is removed by peeling off the gel electrolyte 104. Alternatively, you can wipe it off with a cloth or waste cloth.

[0109] [5. Stack the units and connect the leads] Next, a plurality of units fabricated as described above are stacked (see FIG. 9(A)). In this embodiment, an example using three units is shown. The other surfaces of the current collectors 105 are arranged to face each other. The faces of the motors are arranged facing each other.

[0110] Next, the positive electrode tabs of the plurality of positive electrode current collectors 101 and the positive electrode lead 121 having the sealing layer 120 are , and ultrasonic waves are applied while pressure is applied to create an electrical connection (ultrasonic welding).

[0111] Furthermore, the lead electrodes are subject to stress caused by external force applied after the secondary battery 100 is manufactured. , prone to cracks and breaks.

[0112] Therefore, when ultrasonically welding the positive electrode lead 121 and the positive electrode current collector 101, a bonder having a protrusion is used. By sandwiching the positive electrode tab with a cutting die, a connection region 122 and a curved portion 123 can be formed on the positive electrode tab. (See Figure 9(B)).

[0113] By providing this curved portion 123, it is possible to prevent external force from being applied to the secondary battery 100 after it has been manufactured. Therefore, the reliability of the secondary battery 100 can be improved. can.

[0114] Furthermore, the positive electrode tab is not limited to being formed with the curved portion 123, and the material of the positive electrode current collector may be stainless steel. The positive electrode current collector is made of a strong material such as a resin, and the thickness of the positive electrode current collector is set to 10 μm or less. The structure may be such that stress caused by external force being applied from the outside after fabrication can be easily alleviated.

[0115] Of course, it goes without saying that a plurality of these may be combined to alleviate the stress concentration on the positive electrode tab. do not have.

[0116] Similarly to the positive electrode current collector 101, the negative electrode tab of the negative electrode current collector 105 and the sealing layer 120 are The negative electrode lead 125 is electrically connected by ultrasonic welding.

[0117] [6. Reseal] Next, the electrically connected units are covered with a newly prepared exterior body 107 (FIG. 1 0(A)). The sealing layer 120 provided on the positive electrode lead 121 and the negative electrode lead 1 The side of the exterior body 107 that overlaps the sealing layer 120 provided on the substrate 25 is heat-sealed in the same manner as the first sealing. Then, if necessary, add solvent or electrolyte to form a 10 It is also possible to inject the material from 7b. Then, as with the first sealing, vacuuming, heating and pressurization are performed. Then, the exterior body 107 is sealed to obtain the secondary battery 100 (see FIG. 10(C)).

[0118] [7. Variations] As a modification of the secondary battery 100, a secondary battery 100 is shown in FIG. 11(A). The secondary battery 100 shown in FIG. 1 has a positive electrode lead 121 and a negative electrode lead 122, which are different from the secondary battery 100 shown in FIG. 4 differs from the secondary battery 100 in that the positive electrode lead 121 and the negative electrode lead 25 are disposed in different positions. Although the electrode leads 125 are arranged on the same side of the exterior body 107, in the secondary battery 100 of FIG. The positive electrode lead 121 and the negative electrode lead 125 are disposed on different sides of the outer casing 107. As described above, in the secondary battery according to one aspect of the present invention, the lead electrodes can be freely arranged. Therefore, the degree of freedom in designing a product using the secondary battery of one embodiment of the present invention is high. In addition, the productivity of a product using the secondary battery of one embodiment of the present invention can be improved. It can be increased.

[0119] FIG. 11(B) is a diagram illustrating the manufacturing process of the secondary battery 100 of FIG. 11B, the method for manufacturing the secondary battery 100 in FIG. 4 can be taken into consideration. The gel electrolyte 104 is not shown.

[0120] In addition, in order to make the surface of the film used for the exterior body 107 uneven in advance, it is possible to perform press processing, for example. If the film surface is roughened, it will be easier to use as a secondary battery. The embossing process improves the film surface (or back surface). The concave or convex portion formed on the surface of the film is a space having a volume that is part of the wall of the sealing structure. This closed space is formed by the concave or convex parts of the film, which are bellows-like in shape. It can be said that the rose structure is formed. Also, embossing, which is a type of press processing, Any method that can form a relief on a part of a film may be used.

[0121] This embodiment mode can be implemented in appropriate combination with other embodiment modes and examples. be.

[0122] (Fourth embodiment) In this embodiment, a secondary battery 100 according to one embodiment of the present invention is mounted on a substrate using FIG. This paper describes an electronic device that can

[0123] The secondary battery 100 according to one embodiment of the present invention is flexible and therefore suitable for use in wearable devices. It is suitable.

[0124] For example, it can be mounted on a glasses-type device 400 as shown in FIG. The device 400 has a frame 400a and a display unit 400b. By installing the secondary battery 100 in the temple part of the 400a, the weight balance is good and it can be used continuously. The eyeglass-type device 400 can be used for a long time.

[0125] It can also be installed in a headset type device 401. Headset type device 401 includes at least a microphone part 401a, a flexible pipe 401b, and an earphone. The flexible pipe 401b and the earphone section 401c have multiple A number of secondary batteries 100 can be provided.

[0126] It can also be mounted on a device 402 that can be attached directly to the body. A plurality of secondary batteries 100 can be provided in the two thin housings 402a.

[0127] It can also be mounted on a device 403 that can be attached to clothing. A plurality of secondary batteries 100 can be provided in the thin housing 403a.

[0128] It can also be mounted on a wristband device 404. The wristband device 404 is mounted on the main body 40 4a has a display unit 304b on it, and a plurality of secondary batteries 100 are provided in the main body 404a. This can be done.

[0129] It can also be installed in a wristwatch type device 405. The wristwatch type device 405 has a display The battery pack 405 has a section 405a, and a plurality of secondary batteries 100 can be provided.

[0130] Furthermore, the secondary battery 100 according to one aspect of the present invention is bendable, and therefore can be used in a variety of electronic devices. For example, the stove 410 shown in FIG. The module 411 is attached to the main body 412, and the module 411 is The stove 410 has a motor, a fan, an air outlet 411a, and a thermoelectric generator. After fuel is poured into the opening 412a and ignited, the module 4 is heated using the power of the secondary battery 100. The motor and fan 11 are rotated to blow outside air into the stove 410 through the air outlet 411a. This allows for efficient intake of outside air, making it a stove with strong heat. Furthermore, the heat energy obtained from the combustion of fuel can be used to heat the upper grill 41. 3, the heat energy can be used for cooking in the thermoelectric generator of module 411. The secondary battery 100 can be charged with the converted energy by a power supply. The power stored in 100 can be output from external terminal 411b.

[0131] (Embodiment 5) Furthermore, an example of a mobile object, which is an example of an electrical device, will be described with reference to FIG.

[0132] The secondary battery described in the previous embodiment can be used as the control battery. The battery is charged using external power supply via plug-in technology or wireless charging. In addition, if the moving object is an electric railway vehicle, it can be powered by an overhead wire or conductive rail. It can be charged.

[0133] 13(A) and (B) show an example of an electric vehicle. The electric vehicle 860 has a battery. The power of the battery 861 is output by a control circuit 862. The force is adjusted and supplied to the driving device 863. The control circuit 862 includes a ROM (not shown), It is controlled by a processing unit 864 having RAM, a CPU, etc.

[0134] The drive unit 863 is a DC motor or an AC motor alone, or a combination of a motor and an internal combustion engine. The processing device 864 is configured to receive operation information (acceleration , deceleration, stopping, etc.) and driving information (uphill and downhill slopes, load information on the drive wheels, etc.) The control circuit 862 outputs a control signal based on the input information such as The control signal from the processing unit 864 adjusts the electrical energy supplied from the battery 861. In case an AC motor is installed, the output of the drive unit 863 is controlled by adjusting the speed. However, it also has a built-in inverter that converts direct current to alternating current.

[0135] The battery 861 can be charged by an external power supply using plug-in technology. For example, the battery 861 can be charged from a commercial power source through a power plug. It is converted into a constant DC voltage with a constant voltage value through a conversion device such as an AC / DC converter. The battery 861 can be a secondary battery electrode according to one embodiment of the present invention. By incorporating a secondary battery using this technology, it is possible to contribute to increasing the battery capacity, and it is also convenient. In addition, the improvement of the characteristics of the battery 861 allows the battery 8 If the 61 itself can be made smaller and lighter, it will contribute to reducing the weight of the vehicle, which will improve fuel efficiency. come.

[0136] Note that the electrical devices are not particularly limited to those listed above as long as they include a secondary battery according to one embodiment of the present invention. Needless to say, this is not possible.

[0137] This embodiment mode can be implemented in appropriate combination with other embodiment modes. [Example]

[0138] In this example, the other surface of the negative electrode current collector that does not have the negative electrode active material layer and the other surface that has the negative electrode active material layer are The static friction coefficient was measured on one side of the surface.

[0139] <Static friction coefficient of the other surface of the negative electrode current collector that does not have the negative electrode active material layer> The static friction coefficient between the other surface of the negative electrode current collector that does not have the negative electrode active material layer was determined as follows: .

[0140] As shown in FIG. 15(A), a dry positive electrode current collector is placed on a flat and horizontal glass substrate 1001. Specifically, the following were placed on the glass substrate side in this order: A negative electrode current collector having a negative electrode active material layer 1106a on one side and no negative electrode active material layer on the other side. 1105a, having a negative electrode active material layer 1106b on one side and no negative electrode active material layer on the other side. A negative electrode current collector 1105b is covered with a separator 1103, and a positive electrode active material layer 110 is formed on one side of the negative electrode current collector 1105b. 2a on one side and a positive electrode active material layer 1102b on the other side; A negative electrode current collector 1105c having a negative electrode active material layer 1106c on one side and no negative electrode active material layer on the other side. , a negative electrode current collector having a negative electrode active material layer 1106d on one side and no negative electrode active material layer on the other side. Body 1105d stacked.

[0141] Then, a flat plate 1002 and a weight 100 are placed on the positive electrode current collector, the negative electrode current collector, and the separator. The load from the flat plate 1002 and the weight 1003 is 42.2 g / cm 2 And Ta.

[0142] At this time, the other surface of the negative electrode current collector 1105a that does not have the negative electrode active material and the negative electrode current collector 110 The other surfaces of the negative electrode active material 5b, which do not have the negative electrode active material, are arranged so as to be in contact with each other at the contact surface 1205a. Similarly, the other surface of the negative electrode current collector 1105c that does not have the negative electrode active material was The other surfaces of the negative electrode active material 1205d are arranged so as to be in contact with each other at the contact surface 1205b. did.

[0143] The outermost negative electrode current collectors, that is, the negative electrode current collectors 1105a and 1105b, 05d was fixed to the substrate 1001 at the end 1004 with adhesive tape.

[0144] After that, the positive electrode current collector 1101, which was not fixed as described above, was subjected to a load test using a load tester (Aiko Engineer Attach a handy load indicator (manufactured by Ring Co., Ltd.) and move the load testing machine horizontally at a speed of approximately 1 mm / sec. pulled to.

[0145] The pulling causes slippage between contact surface 1205a and contact surface 1205b. The maximum value of the friction force until the positive electrode current collector 1101 moved 1 cm was measured, and the negative electrode active material The maximum static friction force between the surfaces that do not have the adhesive was used.

[0146] As a result of carrying out the above measurement three times, the maximum static friction force between the other surfaces not having the negative electrode active material was 4 The values ​​were .08N, 4.14N, and 4.23N.

[0147] The negative electrode active material calculated from the maximum static friction force and the load due to the flat plate 1002 and the weight 1003. The static friction coefficients between the other surfaces that did not have the surface were 0.57, 0.58, and 0.59.

[0148] <Static friction coefficient between negative electrode active material layer and separator> The static friction coefficient of the negative electrode current collector on one side having the negative electrode active material layer, more specifically, The static friction coefficient between the separator and one surface of the electrode current collector having the negative electrode active material layer is given as follows: I asked.

[0149] As shown in FIG. 15(B), a dry positive electrode current collector is placed on a flat and horizontal glass substrate 1001. Specifically, the following were placed on the glass substrate side in this order: A negative electrode having a negative electrode active material layer 1106a on one side and a negative electrode active material layer 1106b on the other side. The positive electrode current collector 1105a is covered with a separator 1103, and a positive electrode active material layer 1102a is formed on one side of the positive electrode current collector 1105a. a positive electrode current collector 1101 having a positive electrode active material layer 1102b on one side and a negative electrode A negative electrode current collector 110 having an active material layer 1106c on one side and a negative electrode active material layer 1106d on the other side. 5d stacked.

[0150] Then, a flat plate 1002 and a weight 100 are placed on the positive electrode current collector, the negative electrode current collector, and the separator. The load from the flat plate 1002 and the weight 1003 is 42.2 g / cm 2 And Ta.

[0151] At this time, the negative electrode active material layer 1106b formed on the negative electrode current collector 1105a and the separator 1106b were 103 was placed so that it was in contact with the contact surface 1005a. The negative electrode active material layer 1106c formed on the negative electrode 1106c is in contact with the separator 1103 at the contact surface 1005b. It was placed so that they could touch.

[0152] Then, the negative electrode current collectors, i.e., the negative electrode current collectors 1105a and 1105d, are attached to the end 10 At step 04, the substrate 1001 was fixed with adhesive tape.

[0153] After that, the positive electrode current collector 1101, which was not fixed as described above, was subjected to a load test using a load tester (Aiko Engineer Attach a handy load indicator (manufactured by Ring Co., Ltd.) and move the load testing machine horizontally at a speed of approximately 1 mm / sec. pulled to.

[0154] The pulling causes slippage between contact surface 1005a and contact surface 1005b. The maximum value of the friction force until the positive electrode current collector 1101 moved 1 cm was measured, and the negative electrode active material The maximum static friction force between the surfaces that do not have the adhesive was used.

[0155] The above measurement was performed three times, and the maximum static friction force between the negative electrode active material layer and the separator was 6.23 N. , 6.15N, and 6.17N.

[0156] The maximum static friction force and the load of the flat plate 1002 and the weight 1003 determine the distance between the negative electrode active material layer and the separator. The coefficients of static friction of the rotor were 0.88, 0.86, and 0.85.

[0157] The static friction coefficient between the other surface not having the negative electrode active material layer and the negative electrode active material layer and the separator The static friction coefficient is shown in Figure 16.

[0158] From the above, the other surface not having the negative electrode active material layer is The coefficient of friction is approximately 0.67 times that of the negative electrode, which means that the contact surface has low friction. The contact surface between the surfaces that do not have the active material layer prevents the secondary battery from being bent. , it is possible to release stress caused by the difference between the inner and outer diameters of the curve. [Example]

[0159] In this example, a secondary battery according to one embodiment of the present invention was fabricated and analyzed by X-ray CT (X-ray computer The inside of the secondary battery was observed using a tomography. An evaluation was carried out.

[0160] <Preparation of Secondary Battery> First, the materials and preparation method of the secondary battery used as a sample in this example This article describes:

[0161] For the positive electrode, LiCoO2 is used as the positive electrode active material, and a conductive additive and a binder are added to it. Acetylene black (AB) and polyvinylidene fluoride (PVDF) were mixed. The mixing ratio of these is 90% by weight of LiCoO2, 5% by weight of AB, and 5% by weight of PVDF. The positive electrode current collector was made of aluminum with a thickness of 20 μm. A mixture of LiCoO2, AB, and PVDF was applied to form a positive electrode active material layer.

[0162] Next, for the negative electrode, graphite is used as the negative electrode active material, and carbon black is used as a conductive additive and binder. Vapor grown carbon fiber (VGCF (registered trademark)), carboxymethyl cellulose (CMC) and The blend ratio of graphite was 96% and styrene-butadiene rubber (SBR) was 96%. The amount % was 1 wt % of VGCF (registered trademark), 1 wt % of CMC, and 2 wt % of SBR. The negative electrode current collector was made of copper with a thickness of 18 μm. A mixture of PEG-100 (registered trademark), CMC, and SBR was applied to form a negative electrode active material layer.

[0163] In this example, six electrodes each having a positive electrode active material layer coated on one side were used as the positive electrodes. Six electrodes each having a negative electrode active material layer coated on one side were used. A total of 12 metal foils were used for the positive and negative electrodes.

[0164] Next, the polymer contained in the gel electrolyte is a polymethacrylate polymer. (dimethylaminoethyl methacrylate) was used. More specifically, 50 g of / L of poly(dimethylaminoethyl methacrylate) (PDMAEMA) as a crosslinker 50g / L of N,N,N',N'-tetra(trifluoromethanesulfonyl)dodecane -1,6-diamine (C 12 TFSA) was used. The reaction proceeds without heating to form a gel, but the reaction rate is very slow. Therefore, there is almost no risk of gelling during the unit fabrication process. This is preferable because the reaction proceeds easily and the production process is simple.

[0165] The electrolyte in the gel electrolyte is an organic solvent mixed with EC:DEC=1:1 (weight ratio). The solvent used was one in which 1 mol / L of LiPF6 was dissolved.

[0166] The separator was made of polypropylene.

[0167] The exterior was made of an aluminum laminate film.

[0168] The unit was fabricated using the above materials. Specifically, the fabrication method of the third embodiment was followed. A positive electrode current collector having a positive electrode active material layer on one side and wrapped in a separator, and a positive electrode current collector having a positive electrode active material layer on one side and wrapped in a separator A negative electrode current collector having a negative electrode active material layer is covered with an outer casing, and an electrolytic The liquid was injected and the exterior was sealed. In order to make it easier to remove the gel electrolyte in the subsequent process, A weak adhesive sheet was attached in advance to the surface of the negative electrode current collector that did not have the negative electrode active material layer. After the polymer in the electrolyte solution is fully gelled to form a gel electrolyte, the outer packaging is opened and the unit is Next, peel off the weak adhesive sheet from the negative electrode current collector and remove the outer surface of the unit. The gel electrolyte attached to the electrode was removed.

[0169] Six units prepared as described above were stacked. The surfaces without the porous layer were arranged facing each other.

[0170] Next, the positive electrode tab and the positive electrode lead were ultrasonically welded together, and the negative electrode tab and the negative electrode lead were ultrasonically welded together. The container was then wrapped in a newly prepared outer packaging and resealed.

[0171] <CT scan As described above, a sample of a secondary battery having a capacity of about 300 mAh was fabricated. The sec ondary battery's X-ray CT scan is shown in Fig. 17(A).

[0172] Furthermore, the sample secondary battery was curved and fixed to a frame having a curved surface with a radius of curvature of 40 mm . The X-ray CT scan of the secondary battery at this time is shown in Fig. 17(B).

[0173] The tab of the ultrasonically welded negative electrode is located on the left side of Fig. 17(A) and Fig. 17(B). Comparing the current collector ends on the right side of Fig. 17(A) and Fig. 17(B), it can be seen that when the secondary battery is curved , the contact surface between the negative current collectors is displaced, and the distance between the adhered positive and negative electrodes that affects the charge-discharge characteristics does not change and remains at a constant distance.

[0174] <Charge-discharge characteristics> Also, regarding the secondary battery of the sample in the curved state as shown in Fig. 17(B), the charge-discharge characteristics were evaluated. Note that the charge-discharge characteristics of the 4th cycle after 3 cycles of charge-discharge as an aging process were measured. The results are shown in Fig. 17(C). The upward-sloping curve is the charge curve, and the downward-sloping curve is the discharge curve. Charging was performed at 0.2C equivalent CCCV with a termination voltage of 4.1V . Discharging was performed at 0.2C equivalent CC with a termination voltage of 2.5V.

[0175] Fig. 17(C) shows that the secondary battery of the sample in this embodiment can be charged and discharged normally.

Description of symbols

[0176] 100 Secondary battery 101 Positive current collector 102 Positive electrode active material layer​ 103 Separator 103a Joint 104 Gel Electrolyte 104a Electrolyte 105 Negative electrode current collector 106 Negative electrode active material layer 107 Exterior body 107a Joint Around 107b 111 Positive electrode 115 Negative electrode 120 sealing layer 121 Positive lead 122 Connection Area 123 Curved section 125 Negative lead 201 Contact surface 203 Contact surface 205 Contact surface 301 parts 302 parts 304b Display section 311 distance 400 Eyeglasses-type Device 400a frame 400b Display section 401 Headset-type device 401a Microphone section 401b Flexible Pipe 401c Earphone section 402 Device 402a housing 403 Device 403a housing 404 Armband Device 404a main body 405 Wristwatch-type device 405a Display section 410 stove 411 Module 411a Ventilation outlet 411b External terminal 412 Main Unit 412a opening 413 Grill 860 Electric Vehicles 861 Battery 862 Control circuit 863 Drive Unit 864 Processing equipment 1001 board 1002 board 1004 End 1005a Contact surface 1005b Contact surface 1101 Positive electrode current collector 1102a Cathode active material layer 1102b Cathode active material layer 1103 Separator 1105a Negative electrode current collector 1105b Negative electrode current collector 1105c negative electrode current collector 1105d Negative electrode current collector 1106a Negative active material layer 1106b Negative active material layer 1106c negative electrode active material layer 1106d Negative active material layer 1205a Contact surface 1205b Contact surface

Claims

[Claim 1] A secondary battery having a first positive electrode current collector, a first negative electrode current collector, a second positive electrode current collector, and a second negative electrode current collector, the first positive electrode current collector has a positive electrode active material layer on one surface and no positive electrode active material layer on the other surface; the first negative electrode current collector has a negative electrode active material layer on one surface and no negative electrode active material layer on the other surface; the second positive electrode current collector has a positive electrode active material layer on one surface and no positive electrode active material layer on the other surface, the second negative electrode current collector has a negative electrode active material layer on one surface and no negative electrode active material layer on the other surface, the other surface of the first negative electrode current collector is in contact with the other surface of the second negative electrode current collector, a gel electrolyte and a separator are provided between one surface of the first positive electrode current collector and one surface of the first negative electrode current collector, and between one surface of the second positive electrode current collector and one surface of the second negative electrode current collector; The gel electrolyte includes a polymer, an electrolyte, and a solvent. the first positive electrode current collector, the first negative electrode current collector, the second positive electrode current collector, the second negative electrode current collector, the gel electrolyte, and the separator are covered with an exterior body; the first positive electrode current collector, the first negative electrode current collector, the second positive electrode current collector, the second negative electrode current collector, the separator, and the exterior body are flexible, When the secondary battery is bent, a contact surface between the other surface of the first negative electrode current collector and the other surface of the second negative electrode current collector is misaligned.

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