Electrical devices

Abstract

A battery 1100, which is an example of this electrical device, comprises: an electrical element provided with a current collector, such as a battery element 10 provided with a current collector 11; a lead terminal 18 that is electrically connected to the current collector 11; a junction part 16 that contains an electrically conductive resin and that joins the current collector 11 and the lead terminal 18; and a heat fusion section 17 that is positioned between the junction part 16 and the lead terminal 18 and that contains a solder material. The heat fusion section 17 may also be in contact with the lead terminal 18. The junction part 16 may also be in contact with the current collector 11 and the heat fusion section 17.

Description

[Technical Field] 【0001】 This disclosure relates to electrical devices. [Background technology] 【0002】 In electrical devices equipped with electrical elements, malfunctions may occur due to the rapid overheating of these elements. For example, batteries can overheat rapidly due to short circuits or other reasons. As a technology to suppress such rises in battery temperature, for example, Patent Document 1 discloses a thermal shutdown mechanism that disconnects the electrical connection between the battery cell terminals and the current collector when the battery cell overheats. Specifically, this thermal shutdown mechanism has lead terminals connecting the battery cell terminals and the current collector soldered to the bottom surface of the negative electrode side casing, which is the terminal of the battery cell. When the temperature exceeds the melting point of the solder, the lead terminals separate from the battery cell terminals, thereby disconnecting the electrical connection between the battery cell and the current collector. Patent Document 2 discloses a battery in which a solder material, which is a low-melting-point material, is provided between the positive electrode plate and the terminal of a safety element electrically connected to the positive electrode plate. In the battery of Patent Document 2, the solder material melts due to the rise in battery temperature, thereby disconnecting the electrical connection between the positive electrode plate and the terminal of the safety element. [Prior art documents] [Patent Documents] 【0003】 [Patent Document 1] International Publication No. 2018 / 096926 [Patent Document 2] Japanese Patent Publication No. 2013-098093 [Overview of the project] [Problems that the invention aims to solve] 【0004】 Electrical devices equipped with electrical elements such as batteries are required to prevent ignition or smoke combustion due to abnormal heat generation of these elements. However, conventional electrical devices equipped with the mechanisms described above to address this problem lacked sufficient reliability and had room for improvement. 【0005】 Therefore, this disclosure provides an electrical device with high reliability. [Means for solving the problem] 【0006】 The electrical devices disclosed herein are An electrical element equipped with a current collector, The electrically connected lead terminals of the current collector, A joint containing a conductive resin material and joining the current collector and the lead terminal, A heat-melting portion located between the joint and the lead terminal, and containing solder material, It is equipped with. [Effects of the Invention] 【0007】 This disclosure provides an electrical device with high reliability. [Brief explanation of the drawing] 【0008】 [Figure 1] Figure 1 is a diagram showing the schematic configuration of the battery 1100 according to the first embodiment. [Figure 2] Figure 2 shows a schematic configuration of the battery 1200 according to the second embodiment. [Figure 3] Figure 3 is an enlarged cross-sectional view of the area around the junction in the battery 1300 according to the third embodiment. [Figure 4] Figure 4 is an enlarged cross-sectional view of the area around the junction of battery 1300A, a modified example of battery 1300 according to the third embodiment. It is a diagram showing the schematic configuration. [Figure 5] Figure 5 is an enlarged cross-sectional view of the area around the junction in the battery 1400 according to the fourth embodiment. It is a diagram showing the schematic configuration. [Figure 6] Figure 6 is an enlarged cross-sectional view of the area around the junction in the battery 1500 according to the fifth embodiment. [Modes for carrying out the invention] 【0009】 (Knowledge underlying the present disclosure) As described in the column of [[Background Art]], Patent Documents 1 and 2 disclose batteries in which a technique for suppressing an increase in battery temperature is used. 【0010】 In Patent Document 1, as a thermal cutoff mechanism, the terminal of a lead connecting the terminal of a battery cell and a current collector is soldered to the bottom surface of the negative electrode side exterior of the battery cell, which is the terminal of the battery cell. When the temperature of the lead terminal exceeds the melting temperature of the solder, the electrical connection between the battery cell and the current collector is disconnected by the lead terminal separating from the battery cell terminal. However, when soldering directly to an all-solid-state battery at such a short distance where heat is easily transmitted or directly, due to thermal shock, cracks are likely to occur, for example, at the interface between the electrode layer and the solid electrolyte in the all-solid-state battery. Such cracks due to thermal shock become apparent when the solid material is densified. Therefore, contrary to the high performance improvement of all-solid-state batteries where performance improves when densified, the reliability of the battery decreases. Thus, the conventional technique of directly soldering and joining lead terminals to an all-solid-state battery has problems. 【0011】 Patent Document 2 discloses a battery in which a solder material, which is a low melting point material, is provided between a positive electrode plate and the terminal of a safety element electrically connected to the positive electrode plate. Specifically, a solder material, which is a low melting point material, is provided between the positive electrode plate of the battery element and the positive electrode terminal connected via a positive electrode current collector member and the terminal provided on the safety element. In the battery of Patent Document 2, when the solder material melts due to an increase in battery temperature, the electrical connection between the positive electrode plate and the terminal of the safety element is disconnected. However, when the solder material is disposed between the positive electrode terminal connected via the positive electrode current collector and the terminal of the safety element, when the battery abnormally generates heat, due to the loss in the heat conduction path from the positive electrode plate to the positive electrode terminal and heat dissipation in the process, the responsiveness deteriorates. Therefore, in the worst case, it causes the problem that the solder material does not melt. In particular, in an environment where the outside air temperature is low and the heat dissipation amount is large, the solder material does not rise to the melting temperature, and the conductive path between the positive electrode plate and the terminal of the safety element cannot be disconnected. 【0012】 Therefore, the present inventor has intensively studied an electric device including an electric element, such as a battery including a battery element, in order to solve the above problems of the prior art and further improve reliability. As a result, the present inventor has completed the electric device of the present disclosure shown below. 【0013】 (Embodiment of the present disclosure) Hereinafter, embodiments of the present disclosure will be specifically described with reference to the drawings. 【0014】 Note that all of the embodiments described below show comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement positions of components, connection forms, etc. shown in the following embodiments are merely examples, and are not intended to limit the present disclosure. 【0015】 Also, each drawing is not necessarily drawn precisely. In each drawing, substantially the same configuration is denoted by the same reference numeral, and overlapping descriptions are omitted or simplified. 【0016】 In this specification and the drawings, the x-axis, y-axis, and z-axis indicate three axes of a three-dimensional orthogonal coordinate system. In each embodiment, the z-axis direction is the thickness direction of a battery which is an example of an electric device. Also, in this specification, the "thickness direction" means a direction perpendicular to the plane on which each layer is laminated. 【0017】 Also, in this specification, "plan view" means a case where a battery which is an example of an electric device is viewed along the lamination direction, and "thickness" in this specification is the length in the lamination direction of the battery and each layer. 【0018】 In this specification, "inner" and "outer" in "inner side" and "outer side" etc. mean that when a battery which is an example of an electric device is viewed along the lamination direction, the center side of the battery is "inner" and the peripheral side of the battery is "outer". 【0019】 In this specification, the terms "upper" and "lower" in the configuration of a battery, which is an example of an electrical device, do not refer to the upward (i.e., vertically upward) and downward (i.e., vertically downward) directions in absolute spatial perception, but rather are used as terms defined by the relative positional relationship based on the stacking order in a stacked configuration. Furthermore, the terms "upper" and "lower" apply not only when two components are spaced apart and another component exists between them, but also when two components are placed in close proximity and touching each other. 【0020】 (First Embodiment) An electrical device according to the first embodiment will be described. 【0021】 The electrical device according to the first embodiment comprises an electrical element with a current collector, a joint, a heat melting section, and a lead terminal. The lead terminal is electrically connected to the current collector. The joint contains a conductive resin material and joins the current collector and the lead terminal. The heat melting section is located between the joint and the lead terminal and contains solder material. That is, the current collector and the lead terminal are joined to each other via the joint and the heat melting section. 【0022】 With the above configuration, for example, if the electrical device overheats due to abnormal heat generation in an electrical element, the solder material in the heat melting section melts, separating the lead terminals from the joint. As a result, the electrical device can be electrically disconnected from the external circuit. Furthermore, in the electrical device according to the first embodiment, the current collector and the lead terminals are joined by a joint containing a conductive resin material, thus suppressing the occurrence of cracks due to thermal shock when soldering the lead terminals to the current collector, as in the conventional technology. In this way, the electrical device according to the first embodiment has a mechanism to interrupt the current in the event of abnormal heat generation without degrading the performance of the electrical device. The electrical device according to the first embodiment is less likely to ignite or emit smoke and has high reliability. 【0023】 The following description will use a battery, which is equipped with battery elements such as secondary battery elements, as an example of an electrical device. However, the electrical devices of this disclosure are not limited to the battery described below. The following description may apply to all electrical devices equipped with electrical elements. Other examples of electrical elements include power generation elements such as solar cells and fuel cell elements, energy storage elements such as capacitors, etc. Other examples of electrical devices of this disclosure include power generation devices such as solar cells and fuel cells, energy storage devices, etc. 【0024】 Figure 1 is a diagram showing the schematic configuration of the battery 1100 according to the first embodiment. 【0025】 Figure 1(a) is a cross-sectional view of the battery 1100 according to the first embodiment. Figure 1(b) is a plan view of the battery 1100 viewed from above in the z-axis direction. Figure 1(a) shows a cross-section at the position indicated by line II in Figure 1(b). 【0026】 As shown in Figure 1, the battery 1100 comprises a battery element 10, a junction 16, a heat melting portion 17, and lead terminals 18. The battery element 10 comprises a first current collector 11 and a second current collector 15. The first current collector 11, junction 16, heat melting portion 17, and lead terminals 18 of the battery element 10 are arranged in this order. 【0027】 As shown in Figure 1, the heat-melting portion 17 may be in contact with the lead terminal 18. For example, as shown in Figure 1, the heat-melting portion 17 may cover the entire surface of the lead terminal 18. In this embodiment, the lead terminal 18 covered with the heat-melting portion 17 will hereafter be referred to as the "lead terminal 18 having the heat-melting portion 17". 【0028】 The battery element 10 comprises a first current collector 11, a first active material layer 12, a solid electrolyte layer 13, a second active material layer 14, and a second current collector 15 in this order. The solid electrolyte layer 13 is positioned between the first active material layer 12 and the second active material layer 14. 【0029】 The first current collector 11, the first active material layer 12, the solid electrolyte layer 13, the second active material layer 14, and the second current collector 15 are all rectangular in plan view. The plan view shapes of the first current collector 11, the first active material layer 12, the solid electrolyte layer 13, the second active material layer 14, and the second current collector 15 are not particularly limited. Examples of shapes other than rectangles include circles, ellipses, or polygons. 【0030】 In this specification, the first current collector 11 and the second current collector 15 may be collectively referred to simply as "current collectors." 【0031】 The current collector only needs to be made of a conductive material. 【0032】 The current collector may be made of, for example, stainless steel, nickel, aluminum, iron, titanium, copper, palladium, gold, platinum, or an alloy of two or more of these materials. Foils, plates, or meshes of these materials may also be used as current collectors. 【0033】 The material of the current collector may be selected considering the manufacturing process, operating temperature, operating pressure, battery operating potential applied to the current collector, or conductivity. The current collector material may also be selected considering the tensile strength or heat resistance required by the battery. The current collector may be, for example, high-strength electrolytic copper foil or a clad material consisting of laminated dissimilar metal foils. 【0034】 The current collector may have a thickness of, for example, 10 μm or more and 100 μm or less. 【0035】 The surface of the current collector may be processed to have an uneven, rough surface in order to improve adhesion with the active material layer (i.e., the first active material layer 12 or the second active material layer 14) or the junction 16. This improves, for example, the bonding of the current collector interface, thereby improving the mechanical and thermal reliability and cycle characteristics of the battery. In addition, the contact area between the current collector and the junction 16 is increased, thus reducing electrical resistance. 【0036】 The joint 16 contains a conductive resin material. The conductive resin material is, for example, a mixture of a resin material and a conductive material. Thermosetting resins or thermoplastic resins can be used as the resin material. 【0037】 Examples of thermosetting resins are: (i) Amino resins such as urea resin, melamine resin, and guanamine resin, (ii) Epoxy resins such as bisphenol A type, bisphenol F type, phenol novolac type, and alicyclic type, (iii) Oxetane resin, (iv) Phenolic resins such as resol type and novolac type, (v) Silicone-modified organic resins such as silicone epoxy and silicone polyester The resin may use only one of these materials, or it may use a combination of two or more of these materials. 【0038】 If a thermoplastic resin is used, for example, a resin having a softening point higher than the melting point of the solder material contained in the heat-melting section 17 is selected. 【0039】 The conductive material may consist of metal particles of silver, copper, nickel, zinc, aluminum, palladium, gold, platinum, or alloys of these metals. The shape of the metal particles can be spherical, flake-shaped, needle-shaped, or any other shape. For example, smaller metal particles undergo alloying and diffusion at lower temperatures. Therefore, the particle size and shape of the metal particles are appropriately selected, taking into account the influence of thermal history on process design and battery characteristics. 【0040】 The curing temperature of the conductive resin material is preferably lower than the melting point of the solder material contained in the heat-melting portion 17. With this configuration, when joining the lead terminal 18, which has a heat-melting portion 17 pre-formed on its surface, to the first current collector 11, the joint portion 16 can be formed at a temperature that does not melt the solder material in the heat-melting portion 17. 【0041】 The conductive resin material is, for example, a thermosetting conductive resin material including a thermosetting resin, and may also contain at least one selected from the group consisting of silver and copper. 【0042】 As shown in Figure 1, the joint 16 is in contact with, for example, the first current collector 11 and the heat melting portion 17. 【0043】 As shown in Figure 1, the joint portion 16 is not formed on the opposite side of the lead terminal 18 from the side facing the first current collector 11. 【0044】 The joint portion 16 may have a thickness of, for example, 1 μm or more and 50 μm or less. A thinner joint portion 16 reduces the resistance of the battery 1100. Therefore, a thinner joint portion 16 is advantageous in terms of battery characteristics due to smaller resistance loss, and also improves the temperature accuracy and responsiveness of the lead terminals 18 separating from the joint portion 16 due to heat generation. Accordingly, the joint portion 16 may be made thinner within the limits of the manufacturing process of the joint portion 16 or within the range where reliability can be ensured. Generally, conductive resin materials experience increased resistance due to cracks in their structure when exposed to temperatures above their heat resistance temperature (e.g., 200°C). Therefore, in the battery 1100, in addition to the lead terminals 18 separating from the joint portion 16 when the temperature rises, the joint portion 16 containing the conductive resin material also suppresses electrical connection with the outside. 【0045】 To improve the reliability of the battery 1100, the conductive resin material constituting the joint 16 may have a lower Young's modulus than the materials constituting the current collector, the heat-melt portion 17, and the lead terminals 18. That is, the conductive resin material constituting the joint 16 may be softer than the materials constituting the current collector, the heat-melt portion 17, and the lead terminals 18. This relieves the stress at the interface between the battery element 10 or the first current collector 11 and the joint 16 caused by temperature changes or external stress. As a result, the reliability of the connection between the first current collector 11 and the lead terminals 18 having the heat-melt portion 17 is improved. This relative relationship of Young's modulus can be evaluated from the displacement characteristics or the magnitude of the indentation in response to pressure when a probe is pressed in. 【0046】 The joint 16 may be formed by adjusting the type of material, shape, and composition of components, taking into consideration ease of fabrication in the manufacturing process or stress relaxation performance, i.e., thermal shock resistance or thermal cycling resistance. 【0047】 The joint 16 may have pores. The Young's modulus of the joint 16 can be adjusted by the pores. The state of the pores in the joint 16 can be confirmed by conventional cross-sectional observation methods such as optical microscopy and electron microscopy. It can also be analyzed at any cross-section by means of CT scanning or other methods. 【0048】 The joint 16 may further contain another conductive material in addition to the conductive resin material. This conductive material may be, for example, metal powders such as silver, copper, nickel, palladium, and platinum, which are commonly used as electrodes. As the metal powder, a blend or alloy of multiple metals having different materials or particle sizes may be used, adjusted to ensure conductivity or ohmic contact. 【0049】 The joint 16 may further contain particles of a solid electrolyte, active material, or current collector material in addition to the conductive resin material. This allows the stress at the interface between the joint 16 and the lead terminal 18 having the current collector and heat melting portion 17, which is caused by the expansion or contraction of the battery element 10 due to temperature changes or charging / discharging, to be brought closer to that of the battery element 10. As a result, the stress relaxation performance of the joint 16 is further improved, and the current collector and the lead terminal 18 can be joined with high reliability. 【0050】 The extent of the joint 16 is not limited as long as the first current collector 11 and the lead terminal 18 can be joined to each other via the heat-melting portion 17. Therefore, the joint 16 may be formed in at least a portion of the space between the first current collector 11 and the heat-melting portion 17. For example, the joint 16 may be formed partially by pattern printing on the surface of the first current collector 11 or the heat-melting portion 17. The structure of the joint 16 is not particularly limited as long as the lead terminal 18 can be separated from the joint 16 when the heat-melting portion 17 melts due to heat generation. 【0051】 The joint 16 may be composed of multiple different conductive materials. For example, conductive materials with different coefficients of thermal expansion or hardness may be laminated. This further reduces stress caused by the difference in coefficients of thermal expansion with the current collector or lead terminal 18, thereby improving connection reliability. 【0052】 The specific gravity of the joint 16 is not particularly limited, but from the viewpoint of gravimetric energy density, a lower specific gravity is preferable. From the viewpoint of gravimetric energy density, a conductive resin material having a low specific gravity is preferable. 【0053】 The heat-melting portion 17 contains solder material. As shown in Figure 1, in the battery 1100 according to this embodiment, the heat-melting portion 17 is in contact with the lead terminal 18. The lead terminal 18 may be covered with, for example, a solder material that melts at a low temperature. That is, as shown in Figure 1, the surface of the lead terminal 18 may be covered with the heat-melting portion 17. 【0054】 It is desirable that the solder material has a low melting point. In the event of abnormal heat generation, the solder material may have a melting point of, for example, less than 150°C to facilitate separation of the lead terminals 18 from the joint 16 before ignition or smoke occurs. The solder material may contain Sn and Bi. The solder material may contain Sn and In. Examples of solder materials with a melting point of less than 150°C include materials with a composition of Sn42%-Bi58% or Sn48%-In52%. 【0055】 The thickness of the molten portion 17 may be, for example, 0.3 μm or more and 10 μm, or 1 μm or more and 3 μm or less. The lead terminal 18 may be covered with a solder material plating. That is, the molten portion 17 may be a solder material plating film. Hereinafter, the solder material plating will be referred to as "solder plating". From the viewpoint of heat capacity, a thinner molten portion 17 is preferable. A thin molten portion 17 can improve the temperature accuracy and responsiveness of the lead terminal 18 separating from the joint portion 16 when heat is generated. A thin molten portion 17 is also preferable from the viewpoint of volumetric energy density. With solder plating, the molten portion 17 can be formed on the lead terminal 18 so as to have a thickness of, for example, 0.5 μm or more and 5 μm or less. 【0056】 In the battery 1100 shown in Figure 1, the entire surface of the lead terminal 18 is covered with the heat melting portion 17. However, the lead terminal 18 may be partially covered with the heat melting portion 17, such as only the portion in contact with the joint 16 or only the joint surface. In other words, only the joint portion of the lead terminal 18 may be partially plated by a general partial plating process, such as partial plating only on the portion in contact with the joint 16 or only on the joint surface. That is, the heat melting portion 17 may be provided only on the joint portion with the joint 16 on the surface of the lead terminal 18. This eliminates the need for excess solder material. As a result, a decrease in volumetric energy density or gravimetric energy density can be suppressed. Solder material may also be present on the side surface of the lead terminal 18 that is connected to the joint surface via a ridge. The joint surface of the lead terminal 18 is the surface facing the first current collector 11. The side surface that is connected to the joint surface via a ridge is the side surface relative to the joint surface, that is, the side surface when the joint surface is facing forward. Thus, the melting portion 17 may be in contact with the joint surface and side surface of the lead terminal 18. This allows the lead terminal 18 to separate from the joint surface 16 more easily when heat is generated, even if the conductive resin material constituting the joint 16 spreads over the side surface of the lead terminal 18, because the melting portion 17 is also provided on that side surface. Furthermore, the side surface of the lead terminal 18 that is connected to the joint surface via a ridge tends to be at a lower temperature than the joint surface that is in direct contact with the heat source. For this reason, it is desirable that the melting temperature of the solder material contained in the melting portion 17 provided on the side surface be lower than the melting temperature of the solder material contained in the melting portion 17 provided on the joint surface. In other words, when the melting portion 17 is provided in contact with the joint surface and side surface of the lead terminal 18, it is desirable that the solder material constituting the melting portion 17 includes a first solder material and a second solder material having a lower melting point than the first solder material, with the first solder material in contact with the joint surface and the second solder material in contact with the side surface. 【0057】 The melting temperature of solder material can be adjusted by selecting the composition ratio of the elements it contains (e.g., Sn, Bi, or In). 【0058】 The lead terminal 18 can be any conductor and is not particularly limited, but one with low resistance and high thermal conductivity is especially preferred. 【0059】 Examples of materials for the lead terminal 18 include stainless steel, nickel, aluminum, iron, titanium, copper, or phosphor bronze. 【0060】 The lead terminal 18 may have a thickness of, for example, 200 μm or more and 3000 μm or less. From the viewpoint of weight and volume, the lead terminal 18 may have a thickness of, for example, 500 μm or more and 1000 μm or less. 【0061】 The lead terminals 18 may be formed by die punching or by etching. It is desirable that the thorn-like processing burrs of several tens of micrometers on the end faces of the lead terminals 18 be removed by polishing or brushing. This prevents unnecessary contact between the lead terminals 18 and the first current collector 11 after the lead terminals 18 have separated from the first current collector 11, and prevents damage to the first current collector 11. 【0062】 The bonding surface of the lead terminal 18 is not limited to a flat surface, but may have an uneven structure. For example, the bonding surface of the lead terminal 18 may have irregularities with a height difference of 1 μm or more and 1000 μm or less. This increases the bonding area between the lead terminal 18 and the bonding portion 16, thereby reducing the electrical resistance between the lead terminal 18 and the bonding portion 16 and increasing the bonding strength. As a result, connection reliability can be further improved while reducing the impact on battery characteristics caused by the presence of the bonding portion 16 and the heat-melting portion 17. 【0063】 The shape of the lead terminal 18 is not limited. The cross-section of the lead terminal 18 may be rectangular. The cross-section of the lead terminal 18 may also be trapezoidal. In this case, if the surface of the lead terminal 18 corresponding to the shorter base of the trapezoidal cross-section is used as the joining surface with the first current collector 11, that is, if it is joined to the joint 16 via the heat melting portion 17, the frictional resistance on the side surface when the lead terminal 18 separates from the joint 16 is reduced. As a result, the responsiveness of the lead terminal 18 separating from the joint 16 due to heat generation is improved. 【0064】 The cross-section of the lead terminal 18 may be triangular. In this case, for example, the lead terminal 18 is positioned such that the surface containing the vertex of the triangular cross-section faces the first current collector 11. That is, in this case, for example, the surface containing the vertex of the triangular cross-section of the lead terminal is joined to the joint 16 via the heat melting portion 17. This configuration reduces the frictional resistance on the side surface when the lead terminal 18 separates from the first current collector 11. As a result, the responsiveness of the lead terminal 18 separating from the joint 16 due to heat generation is improved. 【0065】 As shown in Figure 1, the lead terminal 18 may be bent. Having such a bent shape makes it easier for the lead terminal 18 to separate from the joint 16 when the heat melting portion 17 melts. 【0066】 The first active material layer 12 is in contact with, for example, the first current collector 11. The first active material layer 12 contains, for example, a positive electrode active material. That is, the first active material layer 12 is, for example, a positive electrode active material layer. 【0067】 The positive electrode active material is a substance in which metal ions such as lithium (Li) ions and magnesium (Mg) ions are inserted into or removed from its crystal structure at a higher potential than the negative electrode, and oxidation or reduction occurs as a result. 【0068】 When the battery element 10 is, for example, a lithium secondary battery, the positive electrode active material is a substance in which lithium (Li) ions are inserted or removed, and oxidation or reduction occurs accordingly. In this case, the positive electrode active material is, for example, a compound containing lithium and a transition metal element. The compound is, for example, an oxide containing lithium and a transition metal element, or a phosphate compound containing lithium and a transition metal element. 【0069】 Examples of oxides containing lithium and a transition metal element are LiNi x M 1-x O2 (where M is at least one selected from the group consisting of Co, Al, Mn, V, Cr, Mg, Ca, Ti, Zr, Nb, Mo, and W, and 0 < x ≦ 1 is satisfied), such as lithium nickel composite oxides, layered oxides such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2), or lithium manganate having a spinel structure (for example, LiMn2O4, Li2MnO3, or LiMnO2). 【0070】 An example of a phosphate compound containing lithium and a transition metal element is lithium iron phosphate (LiFePO4) having an olivine structure. 【0071】 As the positive electrode active material, sulfides such as sulfur (S) and lithium sulfide (Li2S) may be used. In this case, lithium niobate (LiNbO3) or the like may be coated on or added to the positive electrode active material particles. 【0072】 Only one of these materials may be used as the positive electrode active material, or two or more of these materials may be combined and used. 【0073】 To enhance lithium-ion conductivity or electronic conductivity, the first active material layer 12 may contain materials other than the positive electrode active material in addition to the positive electrode active material. That is, the first active material layer 12 may be a composite layer. Examples of such materials include inorganic solid electrolytes, solid electrolytes such as sulfide solid electrolytes, conductive additives such as acetylene black, or binding binders such as polyethylene oxide and polyvinylidene fluoride. 【0074】 The first active material layer 12 may have a thickness of, for example, 5 μm or more and 300 μm or less. 【0075】 The second active material layer 14 is in contact with, for example, the second current collector 15. The second active material layer 14 contains, for example, a negative electrode active material. That is, the second active material layer 14 is, for example, a negative electrode active material layer. 【0076】 The negative electrode active material is a substance in which metal ions such as lithium (Li) ions and magnesium (Mg) ions are inserted into or removed from its crystal structure at a lower potential than that of the positive electrode, and oxidation or reduction occurs as a result. 【0077】 If the battery element 10 is, for example, a lithium secondary battery, the negative electrode active material is a material in which lithium (Li) ions are inserted or removed, and oxidation or reduction occurs as a result. In this case, examples of negative electrode active materials are carbon materials such as natural graphite, artificial graphite, graphite carbon fiber, and resin-fired carbon, or alloy materials combined with a solid electrolyte. Examples of alloy materials are LiAl, LiZn, Li3Bi, Li3Cd, Li3Sb, Li4Si, Li 4.4 Pb, Li 4.4 Sn, Li 0.17 C, and lithium alloys such as LiC6, lithium titanate (Li4Ti5O 12 ) Oxides of lithium and transition metal elements, such as zinc oxide (ZnO), or silicon oxide (SiO2). x It is a metal oxide such as ). 【0078】 The negative electrode active material may consist of only one of these materials, or a combination of two or more of these materials. 【0079】 To enhance lithium-ion conductivity or electronic conductivity, the second active material layer 14 may contain materials other than the negative electrode active material in addition to the negative electrode active material. Examples of such materials include solid electrolytes such as inorganic solid electrolytes and sulfide solid electrolytes, conductive additives such as acetylene black, or binding binders such as polyethylene oxide and polyvinylidene fluoride. 【0080】 The second active material layer 14 may have a thickness of, for example, 5 μm or more and 300 μm or less. 【0081】 In Figure 1, the first current collector 11, the first active material layer 12, the solid electrolyte layer 13, the second active material layer 14, and the second current collector 15 are, for example, identical in shape, position, and size to one another in a plan view. The solid electrolyte layer 13 is, for example, in contact with the first active material layer 12 and the second active material layer 14. 【0082】 The solid electrolyte layer 13 contains a solid electrolyte. For example, the solid electrolyte layer 13 contains a solid electrolyte as its main component. Here, the main component refers to the component that is present in the largest mass percentage of the solid electrolyte layer 13. The solid electrolyte layer 13 may consist solely of a solid electrolyte. 【0083】 The solid electrolyte may be a known solid electrolyte for batteries that has ionic conductivity. As the solid electrolyte, for example, a solid electrolyte that conducts metal ions such as lithium ions and magnesium ions may be used. 【0084】 As solid electrolytes, inorganic solid electrolytes such as sulfide-based solid electrolytes and oxide-based solid electrolytes can be used, for example. 【0085】 Sulfide-based solid electrolytes are, for example, lithium-containing sulfides. Examples of lithium-containing sulfides are the Li2S-P2S5 system, the Li2S-SiS2 system, the Li2S-B2S3 system, the Li2S-GeS2 system, the Li2S-SiS2-LiI system, the Li2S-SiS2-Li3PO4 system, the Li2S-Ge2S2 system, the Li2S-GeS2-P2S5 system, or the Li2S-GeS2-ZnS system. 【0086】 Oxide-based solid electrolytes are, for example, lithium-containing metal oxides, lithium-containing metal nitrides, lithium phosphate (Li3PO4), or lithium-containing transition metal oxides. Examples of lithium-containing metal oxides are Li2O-SiO2 or Li2O-SiO2-P2O5. Examples of lithium-containing metal nitrides are Li x P y O 1-z N z is. Examples of lithium-containing transition metal oxides are lithium titanates. 【0087】 For the solid electrolyte, only one of these materials may be used, or two or more of these materials may be combined and used. 【0088】 In addition to the above solid electrolyte, the solid electrolyte layer 13 may contain a binder for binding, such as polyethylene oxide and polyvinylidene fluoride. 【0089】 The solid electrolyte layer 13 may, for example, have a thickness of 5 μm or more and 150 μm or less. 【0090】 The material of the solid electrolyte may be composed of an aggregate of particles. Or, the material of the solid electrolyte may be composed of a sintered structure. 【0091】 In Figure 1, the joint 16 and the heat-melted portion 17 are identical in shape, position, and width in a plan view, but are not limited to this. The joint strength and electrical resistance should meet practical requirements. The joint 16 and the heat-melted portion 17 may be circular or elliptical. The joint 16 may have a different shape from the heat-melted portion 17. 【0092】 With the above configuration, the battery 1100 has high reliability, as it can suppress heat generation and overcurrent. 【0093】 In this embodiment, the battery 1100 has a first current collector 11 and a lead terminal 18 joined by a joint 16 containing a conductive resin material, and a heat-melting portion 17 containing solder material is provided between the lead terminal 18 and the joint 16. This configuration of the battery 1100 differs from the battery configurations disclosed in Patent Documents 1 and 2. The battery configurations and problems associated with them disclosed in Patent Documents 1 and 2 are as described above. In this embodiment, the lead terminal 18, which has a heat-melting portion 17, is joined to the first current collector 11 by the joint 16 containing a conductive resin material without subjecting it to thermal shock. Therefore, it is clear that the battery 1100 in this embodiment does not suffer from problems such as cracks and responsiveness due to thermal shock, as seen in the batteries disclosed in Patent Documents 1 and 2. 【0094】 An example of a method for manufacturing the battery 1100 according to this embodiment is described below. Note that the specific substances and numerical values ​​described below are examples only, and the method for manufacturing the battery 1100 is not limited to them. 【0095】 First, a paste is prepared to be used for printing and forming the first active material layer 12 and the second active material layer 14. Hereafter, the first active material layer 12 will be referred to as the positive electrode active material layer, and the second active material layer 14 will be referred to as the negative electrode active material layer. 【0096】 As a solid electrolyte raw material used in the active material layer mixture, for example, a glass powder of Li2S-P2S5 sulfide with an average particle size of approximately 10 μm and mainly composed of triclinic crystals is prepared. As a solid electrolyte raw material, for example, a material with high ionic conductivity (e.g., 2 × 10⁻⁶) is prepared. -3 S / cm to 3×10 -3 Glass powder having an S / cm ratio can be used. 【0097】 As a positive electrode active material, for example, a Li·Ni·Co·Al composite oxide (e.g., LiNi) has an average particle size of about 5 μm and a layered structure. 0.8 Co 0.15 Al 0.05 O2 powder is used. A paste for the positive electrode active material layer is prepared by dispersing a mixture containing the above-mentioned positive electrode active material and the above-mentioned glass powder in an organic solvent or the like. 【0098】 As the negative electrode active material, for example, natural graphite powder with an average particle size of approximately 10 μm is used. A paste for the negative electrode active material layer is prepared by dispersing a mixture containing the above-mentioned negative electrode active material and the above-mentioned glass powder in an organic solvent or the like. 【0099】 Next, copper foil having a thickness of approximately 30 μm is prepared as the material to be used as the first current collector 11 and the second current collector 15. Hereafter, the first current collector 11 will be referred to as the positive electrode current collector, and the second current collector 15 will be referred to as the negative electrode current collector. 【0100】 By screen printing, pastes for the positive electrode active material layer and negative electrode active material layer are printed onto one surface of each copper foil in a predetermined shape and with a thickness of approximately 50 μm to 100 μm. The pastes for the positive electrode active material layer and negative electrode active material layer are dried at 80°C to 130°C to a thickness of 30 μm to 60 μm. This results in a current collector (e.g., copper foil) with a first active material layer 12 (e.g., positive electrode active material layer) and a second active material layer 14 (e.g., negative electrode active material layer) formed on it. 【0101】 Next, a paste for the solid electrolyte layer is prepared by dispersing the mixture containing the aforementioned glass powder in an organic solvent or the like. The paste for the solid electrolyte layer is printed onto the surfaces of the first active material layer 12 and the second active material layer 14 using a metal mask, for example, to a thickness of about 100 μm. After that, the paste for the solid electrolyte layer is dried at 80°C to 130°C. 【0102】 Next, the solid electrolyte layer printed on the first active material layer 12 and the solid electrolyte layer printed on the second active material layer 14 are stacked so that they are in contact with and facing each other. 【0103】 Next, between the pressurized mold plate and the upper surface of the current collector, there is a size divided into three parts in the longitudinal direction, with an elastic modulus of 5 × 10 6 An elastic sheet (70 μm thick) with a Pa of approximately Pa is inserted. 【0104】 Subsequently, the pressurized mold is heated to 50°C at a pressure of 300 MPa for 90 seconds. 【0105】 Next, a thermosetting conductive resin paste containing silver particles with an average particle size of 0.5 μm, which will form the joint 16, is printed onto the surface of the first current collector 11 to a thickness of approximately 20 μm using a metal mask. Then, the lead terminals 18, whose surfaces have been pre-solder-plated, are set into the joint 16, placed in a dryer to prevent movement, and heated to, for example, 120°C in 30 minutes, followed by a 1-hour heat-curing treatment, and then cooled to room temperature. 【0106】 As described above, the battery 1100 is obtained. In this way, the battery 1100 according to this embodiment does not perform soldering directly to the battery element 10 on which the current collector is formed during the manufacturing process, so that thermal shock and thermal stress can be suppressed and a lead terminal mechanism can be provided. 【0107】 The method and sequence of forming the battery 1100 are not limited to the example described above. 【0108】 In the manufacturing method described above, an example was shown in which the paste for the positive electrode active material layer, the paste for the negative electrode active material layer, the paste for the solid electrolyte layer, and the conductive paste were applied by printing, but this is not the only example. Possible printing methods include, for example, the doctor blade method, calendering method, spin coating method, dip coating method, inkjet method, offset method, die coating method, and spray method. 【0109】 In the manufacturing method described above, a thermosetting conductive paste containing silver metal particles was used as an example of the conductive resin paste, but it is not limited to this. Examples of metal components that can be used in the conductive paste include silver, copper, nickel, zinc, aluminum, palladium, gold, platinum, or alloys combining these metals. The shape of the metal particles can be spherical, flake-shaped, needle-shaped, or any other shape. For example, smaller particle sizes allow alloy reactions and diffusion to proceed at lower temperatures. Therefore, the particle size and shape of the metal particles are appropriately selected considering the influence of thermal history on process design and battery characteristics. 【0110】 The resin used in thermosetting conductive resin paste can function as a binding binder, and is selected based on the manufacturing process, including printability and coatability. Examples of resins used in thermosetting conductive paste include thermosetting resins. Examples of thermosetting resins include: (i) Amino resins such as urea resin, melamine resin, and guanamine resin, (ii) Epoxy resins such as bisphenol A type, bisphenol F type, phenol novolac type, and alicyclic type, (iii) Oxetane resin, (iv) Phenolic resins such as resol type and novolac type, (v) Silicone-modified organic resins such as silicone epoxy and silicone polyester The resin may use only one of these materials, or it may use a combination of two or more of these materials. 【0111】 (Second Embodiment) The following describes a battery according to a second embodiment. The battery according to the second embodiment is a modification of the battery according to the first embodiment. Matters described in the first embodiment may be omitted. 【0112】 Figure 2 is a diagram showing the schematic configuration of the battery 1200 according to the second embodiment. Figure 2(a) is a cross-sectional view of the battery 1200 according to the second embodiment. Figure 2(b) is a plan view of the battery 1200 viewed from below in the z-axis direction. Figure 2(a) shows a cross-section at the position indicated by the line II-II in Figure 2(b). 【0113】 As shown in Figure 2, in the battery 1200, the lead terminals 20 are partially plated with solder material. That is, in the battery 1200, a heat-melting portion 19 is formed by the plating film of solder material. The heat-melting portion 19 partially covers the surface of the lead terminal 20. The heat-melting portion 19 has a larger area than the joint portion 16. In addition to the joint surface, the sides of the lead terminal 20 are also covered by the heat-melting portion 19. 【0114】 Battery 1200 offers high reliability, with the ability to suppress heat generation and overcurrent. 【0115】 (Third embodiment) The following describes a battery according to a third embodiment. The battery according to the third embodiment is a modification of the battery according to the first embodiment. Matters described in the first embodiment may be omitted. 【0116】 Figure 3 is an enlarged cross-sectional view of the area around the junction in the battery 1300 according to the third embodiment. 【0117】 As shown in Figure 3, in the battery 1300, the cross-sectional shape of the lead terminal 21 is trapezoidal. The lead terminal 21 is partially plated with solder material, similar to the lead terminal 20 of the battery 1200 according to the second embodiment. In the battery 1300, a heat-melted portion 21 is formed by the plating film of the solder material. In the lead terminal 21, the surface corresponding to the shorter base of the trapezoidal cross-section is joined to the joint portion 16 via the heat-melted portion 22. 【0118】 Figure 4 is an enlarged cross-sectional view of the area around the joint in battery 1300A, a modified example of battery 1300 according to the third embodiment. As shown in Figure 4, the cross-section of the lead terminal 21 may be triangular. In this case, for example, the lead terminal 21 is positioned such that the surface containing the vertices of the triangular cross-section faces the first current collector 11. That is, in this case, for example, the surface containing the vertices of the triangular cross-section of the lead terminal 21 is joined to the joint 16 via the heat melting portion 22. 【0119】 With the above configuration, even if conductive resin material adheres to the lead terminal 21 on its side surface, frictional resistance is reduced, and the lead terminal 21 is more likely to separate from the joint 16 when heat is generated. 【0120】 Thus, the battery 1300 has high reliability, capable of suppressing heat generation and overcurrent. 【0121】 (Fourth Embodiment) The following describes a battery according to the fourth embodiment. The battery according to the fourth embodiment is a modification of the battery according to the first embodiment. Matters described in the first embodiment may be omitted. 【0122】 Figure 5 is an enlarged cross-sectional view of the area around the junction in the battery 1400 according to the fourth embodiment. 【0123】 As shown in Figure 5, in the battery 1400, the shape of the joining surface of the lead terminal 23 is uneven. Therefore, in the battery 1400, the lead terminal 23 is joined to the joining portion 16 via the heat melting portion 24 on a surface having an uneven structure. 【0124】 The uneven structure in Figure 5 is just one example; the uneven structure may also be triangular in shape. 【0125】 This configuration increases the contact area between the lead terminal 23 and the joint 16, thereby reducing the connection resistance between the lead terminal 23 and the joint 16. As a result, the impact on battery characteristics due to the presence of the joint 16 and the heat-melting portion 24 can be reduced, and the connection strength can be improved. 【0126】 (Fifth embodiment) The following describes a battery according to the fifth embodiment. The battery according to the fifth embodiment is a modification of the battery according to the first embodiment. Matters described in the first embodiment may be omitted. 【0127】 Figure 6 is an enlarged cross-sectional view of the area around the junction in the battery 1500 according to the fifth embodiment. 【0128】 In the battery 1500, the lead terminals 25 are covered with a first solder material 26 and a second solder material 27. That is, the lead terminals 25 are covered with two types of solder materials. The first solder material 26 is in contact with the bonding surface of the lead terminals 25. The second solder material 27 is in contact with the side surface of the lead terminals 25. The second solder material 27 has a lower melting point than the first solder material 26. 【0129】 This configuration makes it easier to separate the lead terminal 25 from the joint 16, even when the joint 16 is located on the side of the lead terminal 25. Furthermore, the temperature accuracy and responsiveness of the separation of the lead terminal 25 from the joint 16 due to heat generation are improved. 【0130】 Although the electrical devices of this disclosure have been described above based on embodiments, this disclosure is not limited to these embodiments. Without departing from the spirit of this disclosure, various modifications to the embodiments that a person skilled in the art could conceive, and other forms constructed by combining some of the components of the embodiments, are also included in the scope of this disclosure. 【0131】 Furthermore, the above embodiments can be modified, replaced, added, or omitted in various ways within the scope of the claims or their equivalents. [Industrial applicability] 【0132】 The electrical devices of this disclosure can be used, for example, as secondary batteries used in various electronic devices or automobiles.

Claims

[Claim 1] An electrical element equipped with a current collector, The electrically connected lead terminals of the current collector, A joint containing a conductive resin material and joining the current collector and the lead terminal, A heat-melting portion located between the joint and the lead terminal, and containing solder material, An electrical device equipped with, The thickness of the joint is 1 μm or more and 50 μm or less. The aforementioned electrical element is a battery element, an energy storage element, or an energy generating element. Electrical devices. [Claim 2] The melting point of the aforementioned solder material is less than 150°C. The electrical device according to claim 1. [Claim 3] The aforementioned solder material contains Sn and Bi. The electrical device according to claim 1 or 2. [Claim 4] The aforementioned solder material contains Sn and In. The electrical device according to claim 1 or 2. [Claim 5] The aforementioned heat-melted portion is in contact with the lead terminal. An electrical device according to any one of claims 1 to 4. [Claim 6] The aforementioned molten portion covers the entire surface of the lead terminal. An electrical device according to any one of claims 1 to 5. [Claim 7] The aforementioned molten portion is a plating film. An electrical device according to any one of claims 1 to 6. [Claim 8] The joint portion is in contact with the current collector and the heat melting portion. An electrical device according to any one of claims 1 to 7. [Claim 9] The aforementioned joint is not formed on the opposite side of the lead terminal from the side facing the current collector. An electrical device according to any one of claims 1 to 8. [Claim 10] The lead terminal includes a bonding surface facing the current collector and a side surface relative to the bonding surface, The aforementioned molten portion is in contact with the joining surface and the side surface. An electrical device according to any one of claims 1 to 9. [Claim 11] The solder material includes a first solder material and a second solder material. The first solder material is in contact with the joining surface, The second solder material is in contact with the side surface, The second solder material has a lower melting point than the first solder material. The electrical device according to claim 10. [Claim 12] The curing temperature of the conductive resin material is lower than the melting point of the solder material. An electrical device according to any one of claims 1 to 11. [Claim 13] The conductive resin material is a thermosetting conductive resin material and contains at least one selected from the group consisting of silver and copper. An electrical device according to any one of claims 1 to 12. [Claim 14] The lead terminal has an uneven structure on the bonding surface of the lead terminal facing the current collector. An electrical device according to any one of claims 1 to 13. [Claim 15] The cross-sectional shape of the lead terminal is trapezoidal. In the lead terminal, the surface corresponding to the shorter base of the trapezoid is joined to the joint via the heat-melting portion. An electrical device according to any one of claims 1 to 14. [Claim 16] The cross-sectional shape of the lead terminal is triangular. In the lead terminal, the surface including the vertex of the triangle is joined to the joint via the heat-melting portion. An electrical device according to any one of claims 1 to 14. [Claim 17] The aforementioned lead terminal is bent. An electrical device according to any one of claims 1 to 16. [Claim 18] The aforementioned current collector is a positive electrode current collector, The lead terminal is electrically connected to the positive electrode current collector. An electrical device according to any one of claims 1 to 17.