Secondary batteries, electronic devices and power tools

Abstract

To provide a battery capable of keeping electrical insulation between a battery lid and a battery can even if exposed to an aqueous solution such as seawater.SOLUTION: The present invention relates to a secondary battery comprising: an electrode wound body having a structure in which a belt-like positive electrode and a belt-like negative electrode are stacked and wound via a separator; a battery can in which the electrode wound body is accommodated and which comprises a crimp part; a battery lid comprising a flange part; and a gasket disposed between the inside of the crimp part of the battery can and the flange part of the battery lid. The gasket includes a gasket face which is exposed from a tip end of the crimp part to the outside, and is covered by an insulation layer from a top of the crimp part to at least a part of the gasket face.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a secondary battery, an electronic device, and a power tool. [Background technology]

[0002] Lithium-ion batteries and other secondary batteries are increasingly being used in machinery and tools. For example, they are sometimes used as batteries in electric reels at the beach or on a boat. In these cases, seawater can splash onto the reel or be dropped into it, exposing the lithium-ion battery to seawater.

[0003] Patent Document 1 discloses that by covering the battery lid from a portion to the gasket with a fluororesin sealant, it is possible to prevent seawater from entering the battery even when the battery is exposed to seawater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-008602 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, when the battery is submerged in seawater, iron from the battery lid dissolves in the seawater, and the dissolved iron precipitates from the battery can to the battery lid, resulting in an electrical connection between the battery lid and the battery can, causing a short circuit.

[0006] Therefore, an object of the present invention is to provide a secondary battery that can maintain electrical insulation between the battery lid and the battery can even when exposed to an aqueous solution such as seawater. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides an electrode winding body having a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound with a separator interposed therebetween; a battery can containing an electrode winding and having a crimp portion; a battery lid having a flange portion; a gasket disposed between the inside of the crimped portion of the battery can and the flange portion of the battery lid; and The gasket has a gasket surface exposed to the outside from a tip end of the crimped portion, The gasket is covered with an insulating layer from the top of the crimped portion to at least a part of the gasket surface. And, The battery cover material contains iron, The insulating layer is made of fluororesin, and the thickness of the insulating layer is 20 μm or more and 49 μm or less, The insulating layer is positioned so that part of the gasket is exposed. It is a secondary battery. The present invention also provides an electrode winding body having a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound with a separator interposed therebetween; a battery can containing an electrode winding and having a crimp portion; a battery lid having a flange portion; a gasket disposed between the inside of the crimped portion of the battery can and the flange portion of the battery lid; and The gasket has a gasket surface exposed to the outside from a tip end of the crimped portion, The gasket is covered with an insulating layer from the top of the crimped portion to at least a part of the gasket surface, The battery cover material contains iron, The insulating layer is made of fluororesin, and the thickness of the insulating layer is 20 μm or more and 49 μm or less, The insulating layer covers substantially the entire exposed surface of the flange portion so as not to cover the surface rising in the vertical direction on the exposed surface of the flange portion. It is a secondary battery. [Effects of the Invention]

[0008] According to at least one embodiment of the present invention, electrical insulation between the battery lid and the battery can can be maintained even when the secondary battery is exposed to salt water. Note that the effects exemplified in this specification should not be construed as limiting the scope of the present invention. [Brief explanation of the drawings]

[0009] [Figure 1]FIG. 1 is a cross-sectional view of a battery according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view for explaining Example 1, Example 6, Comparative Example 2 and Comparative Example 4. [Figure 3] FIG. 3 is a cross-sectional view for explaining the second embodiment. [Figure 4] FIG. 4 is a cross-sectional view for explaining the third embodiment. [Figure 5] FIG. 5 is a cross-sectional view for explaining Example 4 and Comparative Example 5. [Figure 6] FIG. 6 is a cross-sectional view for explaining the fifth embodiment. [Figure 7] FIG. 7 is a cross-sectional view for explaining the comparative example 1. As shown in FIG. [Figure 8] FIG. 8 is a cross-sectional view for explaining the third comparative example. [Figure 9] FIG. 9 is a connection diagram used to explain a battery pack as an application example of the present invention. [Figure 10] FIG. 10 is a connection diagram used to explain a power tool as an application example of the present invention. [Figure 11] FIG. 11 is a connection diagram used to explain an electric vehicle as an application example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The description will be made in the following order. <1. One embodiment> <2. Modifications> <3. Application Examples> The following embodiments and the like are preferred specific examples of the present invention, and the content of the present invention is not limited to these embodiments and the like.

[0011] In the embodiments of the present invention, a cylindrical lithium ion battery will be described as an example of the secondary battery, but batteries other than lithium ion batteries and batteries other than cylindrical batteries may also be used.

[0012] <1. One embodiment> First, the overall configuration of the lithium-ion battery will be described. Fig. 1 is a schematic cross-sectional view of a lithium-ion battery 1. Fig. 2 is an enlarged view of the upper part of Fig. 1. The lithium-ion battery 1 is, for example, a cylindrical lithium-ion battery 1 in which an electrode winding body 20 is housed inside a battery can 11, as shown in Fig. 1.

[0013] Specifically, the lithium ion battery 1 includes a pair of insulating plates 12 and 13 and an electrode winding body 20 inside a cylindrical battery can 11.

[0014] [Insulating board] The insulating plates 12 and 13 are sheet-like members having surfaces that are approximately perpendicular to the winding axis direction of the electrode winding body 20 (the vertical direction in FIG. 1). The insulating plates 12 and 13 are arranged so as to sandwich the electrode winding body 20 between them. Materials that can be used for the insulating plates 12 and 13 include polyethylene terephthalate (PET), polypropylene (PP), and bakelite. Bakelite includes paper bakelite and cloth bakelite, which are made by applying phenolic resin to paper or cloth and then heating it.

[0015] [Crimped structure] At the open end 11N of the battery can 11, the battery lid 14 and the safety valve mechanism 30 are crimped via a gasket 15 at the bent portion 11P, forming a crimped structure 11R. As a result, when the electrode wound body 20 and the like are housed inside the battery can 11, the battery can 11 is sealed.

[0016] [Battery cover] The battery lid 14 is a member that closes the open end 11N of the battery can 11 when the electrode winding body 20 and other components are housed inside the battery can 11. The battery lid 14 contains the same material as the material from which the battery can 11 is formed. A central region of the battery lid 14 protrudes in the vertical direction in FIG. 1. Meanwhile, the peripheral region of the battery lid 14 other than the central region (hereinafter referred to as the "flange portion") is in contact with the safety valve mechanism 30. The battery lid 14 is the positive electrode (+ electrode, second polarity) of the battery 1. Although not shown, a PTC element such as a thermistor may be provided between the flange portion of the battery lid 14 and the safety valve mechanism 30.

[0017] [gasket] The gasket 15 is a member that is interposed between the inside of the folded portion 11P (hereinafter referred to as the crimped portion 11P) of the battery can 11 and the end of the battery lid 14, thereby sealing the gap between the crimped portion 11P and the battery lid 14. The surface of the gasket 15 may be coated with, for example, asphalt. In the present invention, as shown in FIGS. 1 and 2, the upper end of the gasket 15 has a surface (hereinafter referred to as the gasket surface 15A) that is exposed to the outside from the tip of the crimped portion 11P (the tip 55 of the battery can 11). In addition, it is desirable that the lower portion of the gasket 15 extends toward the electrode winding body 20.

[0018] The gasket 15 contains an insulating material. The type of insulating material is not particularly limited, but is preferably a polymer material such as polybutylene terephthalate (PBT) or polypropylene (PP). This is because the gap between the crimp portion 11P and the battery lid 14 is sufficiently sealed while electrically isolating the battery can 11 and the battery lid 14 from each other.

[0019] [Battery can] The battery can 11 is a member that houses the electrode winding body 20. The battery can 11 is a cylindrical container with one open end and the other closed end. That is, the battery can 11 has one open end (open end 11N). The battery can 11 contains one or more types of metal materials such as iron, aluminum, and alloys thereof. However, the surface of the battery can 11 may be plated with one or more types of metal materials such as nickel. The can bottom of the battery can 11 is the negative electrode (negative electrode, first polarity) of the battery 1. Since the entire battery can 11 is electrically connected to the can bottom of the battery can 11, the entire battery can 11 is the negative electrode (negative electrode, first polarity) of the battery 1.

[0020] [Insulating layer] As shown in FIG. 2 , the battery can 11, gasket 15, and battery lid 14 are partially coated with an insulating layer 41. The insulating layer 41 is formed to prevent iron from precipitating between the battery can 11 and the battery lid 14 and causing a short circuit when the battery 1 is exposed to saltwater (hereinafter, saltwater will be used as a model for seawater). The insulating layer 41 shown in the examples and comparative examples described below is a fluororesin, and is formed by applying and drying WOP (a material manufactured by Noda Screen Co., Ltd.). The insulating layer 41 is electrically insulating and waterproof, and contains a fluorescent agent that reacts to ultraviolet light. Therefore, when ultraviolet light is irradiated and colored, the fluorescent agent emits light, confirming that the area is covered with the insulating layer 41. This allows for pre-shipment inspection of the battery 1, making it possible to identify defective products that are not properly covered with the insulating layer 41.

[0021] [Safety valve mechanism] When the pressure inside the battery can 11 (internal pressure) increases, the safety valve mechanism 30 releases the internal pressure by releasing the sealed state of the battery can 11 as necessary. The increase in the internal pressure of the battery can 11 is caused by gas generated due to the decomposition reaction of the electrolyte solution during charging and discharging.

[0022] [Electrode winding body] In a cylindrical lithium-ion battery, a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are spirally wound with a separator 23 sandwiched therebetween and housed in a battery can 11 in a state impregnated with an electrolyte. Although not shown, the positive electrode 21 and the negative electrode 22 are formed by forming a positive electrode active material layer and a negative electrode active material layer on one or both sides of the positive electrode foil and the negative electrode foil, respectively. The material of the positive electrode foil is a metal foil containing aluminum or an aluminum alloy. The material of the negative electrode foil is a metal foil containing nickel, a nickel alloy, copper, or a copper alloy. The separator 23 is a porous, insulating film that electrically insulates the positive electrode 21 and the negative electrode 22 while allowing lithium ions to move.

[0023] A space (central space 20C) is provided in the center of the electrode winding body 20 when the positive electrode 21, the negative electrode 22, and the separator 23 are wound, and a center pin 24 is inserted into the central space 20C (see FIG. 1). However, the center pin 24 can be omitted.

[0024] A positive electrode lead 25 is connected to the positive electrode 21, and a negative electrode lead 26 is connected to the negative electrode 22 (see FIG. 1). The positive electrode lead 25 contains a conductive material such as aluminum. The positive electrode lead 25 is connected to a safety valve mechanism 30 and is electrically connected to the battery lid 14. The negative electrode lead 26 contains a conductive material such as nickel. The negative electrode lead 26 is electrically connected to the battery can 11. The detailed configurations and materials of the positive electrode 21, negative electrode 22, separator 23, and electrolyte will be described later.

[0025] [Positive electrode] The positive electrode active material layer contains at least a positive electrode material (positive electrode active material) capable of absorbing and releasing lithium, and may further contain a positive electrode binder, a positive electrode conductive agent, etc. The positive electrode material is preferably a lithium-containing compound (for example, a lithium-containing composite oxide or a lithium-containing phosphate compound).

[0026] The lithium-containing composite oxide has, for example, a layered rock salt type or spinel type crystal structure, and the lithium-containing phosphate compound has, for example, an olivine type crystal structure.

[0027] The positive electrode binder contains synthetic rubber or a polymer compound. The synthetic rubber is styrene butadiene rubber, fluorine-based rubber, ethylene propylene diene, etc. The polymer compound is polyvinylidene fluoride (PVdF), polyimide, etc.

[0028] The positive electrode conductive agent is a carbon material such as graphite, carbon black, acetylene black, or ketjen black, but may also be a metal material or a conductive polymer.

[0029] [Negative electrode] The surface of the negative electrode foil is preferably roughened. This is because the so-called anchor effect improves the adhesion of the negative electrode active material layer to the negative electrode foil. For example, a method of roughening the surface may involve forming fine particles using an electrolytic method to create irregularities on the surface of the negative electrode foil. Copper foil produced by an electrolytic method is generally called electrolytic copper foil.

[0030] The negative electrode active material layer contains at least a negative electrode material (negative electrode active material) capable of absorbing and releasing lithium, and may further contain a negative electrode binder, a negative electrode conductive agent, and the like.

[0031] The negative electrode material includes, for example, a carbon material. This is because the change in the crystal structure during the absorption and desorption of lithium is very small, and therefore a high energy density can be stably obtained. In addition, the carbon material also functions as a negative electrode conductive agent, thereby improving the conductivity of the negative electrode active material layer.

[0032] The carbon material may be graphitizable carbon, non-graphitizable carbon, graphite, low-crystalline carbon, or amorphous carbon, and may have a fibrous, spherical, granular, or flaky shape.

[0033] In addition, the negative electrode material includes, for example, metal-based materials. Examples of metal-based materials include Li (lithium), Si (silicon), Sn (tin), Al (aluminum), Zr (zinc), and Ti (titanium). The metal-based elements form compounds, mixtures, or alloys with other elements. Examples thereof include silicon oxide (SiO x (0 < x ≤ 2)), silicon carbide (SiC), or an alloy of carbon and silicon, and lithium titanate (LTO).

[0034] In the lithium-ion battery 1, when the open-circuit voltage (i.e., the battery voltage) at full charge is 4.25 V or higher, the amount of lithium released per unit mass is larger when using the same positive electrode active material as compared with the case where the open-circuit voltage at full charge is low. As a result, a high energy density can be obtained.

[0035] [Separator] The separator 23 is a porous membrane containing a resin, and may be a laminated membrane of two or more porous membranes. The resin is, for example, polypropylene and polyethylene.

[0036] The separator 23 may include a resin layer on one or both sides thereof with the porous membrane as a base layer. This is because the adhesion of the separator 23 to each of the positive electrode 21 and the negative electrode 22 is improved, thereby suppressing the distortion of the electrode winding body 20.

[0037] The resin layer contains a resin such as PVdF. When forming this resin layer, a solution in which the resin is dissolved in an organic solvent is applied to the base layer, and then the base layer is dried. Alternatively, the base layer may be immersed in the solution and then dried. It is preferable that the resin layer contains inorganic particles or organic particles from the viewpoints of heat resistance and improvement of battery safety. Examples of the types of inorganic particles include aluminum oxide, aluminum nitride, aluminum hydroxide, magnesium hydroxide, boehmite, talc, silica, and mica. Instead of the resin layer, a surface layer mainly composed of inorganic particles formed by a sputtering method, an ALD (atomic layer deposition) method, or the like may be used.

[0038] [Electrolyte] The electrolyte solution contains a solvent and an electrolyte salt, and may further contain additives as necessary. The solvent is a non-aqueous solvent such as an organic solvent, or water. An electrolyte solution containing a non-aqueous solvent is called a non-aqueous electrolyte solution. The non-aqueous solvent is a cyclic carbonate ester, a chain carbonate ester, a lactone, a chain carboxylic acid ester, a nitrile (mononitrile), or the like.

[0039] A typical example of the electrolyte salt is a lithium salt, but salts other than lithium salts may also be included. Examples of lithium salts include lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium methanesulfonate (LiCHSO), lithium trifluoromethanesulfonate (LiCFSO), and dilithium hexafluorosilicate (LiSF). Mixtures of these salts can also be used, and a mixture of LiPF and LiBF is particularly preferred from the perspective of improving battery performance. The content of the electrolyte salt is not particularly limited, but is preferably 0.3 mol / kg to 3 mol / kg relative to the solvent.

[0040] [How to make a lithium-ion battery] Next, a method for manufacturing a secondary battery will be described. First, when manufacturing the positive electrode 21, a positive electrode mixture is prepared by mixing a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent. Next, the positive electrode mixture is dispersed in an organic solvent to prepare a paste-like positive electrode mixture slurry. Next, the positive electrode mixture slurry is applied to both sides of a positive electrode foil and then dried to form a positive electrode active material layer. Next, while heating the positive electrode active material layer, the positive electrode active material layer is compression-molded using a roll press to obtain the positive electrode 21.

[0041] The negative electrode 22 is also produced in the same manner as the positive electrode 21 described above.

[0042] Next, a positive electrode lead 25 and a negative electrode lead 26 are connected to the positive electrode foil and the negative electrode foil, respectively, using a welding method. Subsequently, the positive electrode 21 and the negative electrode 22 are stacked with the separator 23 interposed therebetween, and then wound. A fixing tape is attached to the outermost peripheral surface of the separator 23, thereby forming the electrode wound body 20.

[0043] Next, with an insulator in contact with the side of the electrode winding body 20 where the negative electrode lead 26 is exposed, the electrode winding body 20 is housed inside the battery can 11, and the can bottom and the negative electrode lead 26 are connected by welding. Next, an insulator is also placed on the side of the electrode winding body 20 where the positive electrode lead 25 is exposed, and one end of the positive electrode lead 25 is connected to the safety valve mechanism 30 by welding.

[0044] Next, a beading machine (grooving machine) is used to process the battery can 11, thereby forming a depression in the battery can 11. Next, an electrolyte solution is injected into the battery can 11, and the electrode wound body 20 is impregnated with the electrolyte solution. Next, the battery lid 14 and the safety valve mechanism 30 are housed inside the battery can 11 together with the gasket 15.

[0045] Finally, as shown in FIG. 1, the battery lid 14 and the safety valve mechanism 30 are crimped together at the open end 11N of the battery can 11 via the gasket 15, thereby forming a crimped structure 11R. [Example]

[0046] The present invention will be specifically described below based on examples of voltage drop rates before and after a saltwater durability test using the battery 1 fabricated as described above. Note that the present invention is not limited to the examples described below.

[0047] 2 to 8 are cross-sectional views of the upper part of the battery 1 (near the battery lid). The size of the battery 1 in the example and comparative example is 18650 (diameter 18 mm, height 65 mm). The positive electrode active material layer of the battery 1 contains a material with an olivine-type crystal structure. Hereinafter, the side surface 54 of the battery can 11 refers to the portion from the edge of the crimped portion of the battery can (hereinafter referred to as the crimped portion 51) to just before the constricted portion 56, as shown in Figures 2 to 8. The crimped portion includes not only the apex of the crimped portion but also the area near the apex. The highest point (upward as one looks into Figure 1) of the curve representing the surface of the bent portion 11P in Figure 1 is the apex of the crimped portion.

[0048] [Example 1] As shown in FIG. 2, the area covered with the insulating layer 41 extends from the crimp top 51 of the battery can 11 to the gasket surface 15A and a portion of the surface of the flange portion of the battery lid 14 exposed to the outside (hereinafter referred to as the flange surface 52), and the thickness of the insulating layer 41 is 20 μm.

[0049] [Example 2] As shown in FIG. 3, the area covered with the insulating layer 41 was from the crimp top 51 of the battery can 11 to a part of the gasket surface 15A, and the thickness of the insulating layer 41 was set to 20 μm.

[0050] [Example 3] 4, the area covered with the insulating layer 41 extends from the side surface 54 of the battery can 11 to the crimp top 51, the gasket surface 15A, the flange surface 52 of the battery lid 14, and the terminal portion 53, and the thickness of the insulating layer 41 is 20 μm. Note that in order to provide a terminal function as the positive electrode of the battery 1, the area near the center of the terminal portion 53 (the center of the cylindrical battery lid, not shown) is excluded from the area covered by the insulating layer 41.

[0051] [Example 4] As shown in Figure 5, the area covered with the insulating layer 41 was from the side surface 54 of the battery can 11 to the crimp top 51, the gasket surface 15A, and almost the entire area of the flange surface 52 of the battery lid 14, and the thickness of the insulating layer 41 was 20 µm.

[0052] [Example 5] As shown in FIG. 6, the area covered with the insulating layer 41 was from the side surface 54 of the battery can 11 to a part of the gasket surface 15A, and the thickness of the insulating layer 41 was set to 20 μm.

[0053] [Example 6] As shown in Figure 2, the area covered with the insulating layer 41 was from the crimp top 51 of the battery can 11 to the gasket surface 15A and part of the flange surface 52 of the battery lid 14, and the thickness of the insulating layer 41 was 49 µm.

[0054] [Comparative Example 1] As shown in FIG. 7, it was not covered with an insulating layer 41.

[0055] Comparative Example 2 As shown in Figure 2, the area covered with the insulating layer 41 was from the crimp top 51 of the battery can 11 to the gasket surface 15A and part of the flange surface 52 of the battery lid 14, and the thickness of the insulating layer 41 was 15 µm.

[0056] Comparative Example 3 As shown in FIG. 8, the area covered with the insulating layer 41 was from the side surface 54 to the tip 55 of the battery can 11, and the thickness of the insulating layer was 25 μm.

[0057] Comparative Example 4 As shown in Figure 2, the area covered with the insulating layer 41 was from the crimp top 51 of the battery can 11 to the gasket surface 15A and part of the flange surface 52 of the battery lid 14, and the thickness of the insulating layer 41 was 50 µm.

[0058] Comparative Example 5 As shown in Figure 5, the area covered with the insulating layer 41 was almost the entire area from the side surface 54 of the battery can 11 to the gasket surface 15A and the flange surface 52 of the battery lid 14, and the thickness of the insulating layer 41 was 50 µm.

[0059] [evaluation] A saltwater durability test was conducted on the battery 1 of the above example to measure the voltage drop rate. The saltwater durability test involves wrapping cellophane tape around the side surface 54 of the battery can 11 to form a cylindrical shape, creating a cellophane tape cylinder around the top of the battery can 11 and the battery lid 14, pouring saltwater (a 1 wt% sodium chloride solution) into the cylinder so that the water level was 10 mm high, and leaving the cylinder at room temperature (approximately 23°C) for two hours. The voltage drop rate is the ratio of the voltage drop of the battery 1 after the saltwater durability test to the voltage before the test, and five batteries were tested for each example.

[0060] [Table 1] TIFF0007718060000001.tif78126

[0061] The voltage drop rates of Examples 1 to 6 were relatively low at 2% or less, whereas the voltage drop rates of Comparative Examples 1 to 3 were relatively high at 5% or more. Although the voltage drop rates of Comparative Examples 4 and 5 were relatively low, Comparative Examples 4 and 5 had a problem in that the insulating layer 41 was thick, and therefore took a long time to dry. In particular, Comparative Example 5 had a problem in that the thickness of the insulating layer 41 relative to the outer diameter of the battery 1 was significantly large. Table 1 shows that when the insulating layer 41 covers the battery can 11 from the crimp top 51 to at least a portion of the gasket surface 15A, and the insulating layer 41 has a thickness of 20 μm to 49 μm, electrical insulation between the battery lid 14 and the battery can 11 can be maintained even when the battery 1 is exposed to seawater (salt water).

[0062] <2. Modifications> Although one embodiment of the present invention has been specifically described above, the content of the present invention is not limited to the above-described embodiment, and various modifications based on the technical concept of the present invention are possible.

[0063] In one embodiment, the size of the battery 1 is 18650, but it may be 21700 (diameter 21 mm, height 70 mm) or other sizes. In the embodiment, the insulating layer 41 is made of fluororesin, but it may be made of silicone resin or epoxy resin, or any other material as long as it has electrical insulation and waterproof properties. In the embodiment and Examples 1 to 6, the insulating layer 41 has been described as having a single layer structure, but the insulating layer may be divided into a plurality of layers and scattered so as to cover desired areas. In one embodiment, the first polarity is negative and the second polarity is positive, but the first polarity may be positive and the second polarity may be negative.

[0064] <3. Application Examples> (1) Battery pack 9 is a block diagram showing an example of a circuit configuration when a secondary battery according to an embodiment or example of the present invention is applied to a battery pack 300. The battery pack 300 includes an assembled battery 301, a switch unit 304 including a charge control switch 302a and a discharge control switch 303a, a current detection resistor 307, a temperature detection element 308, and a control unit 310. The control unit 310 controls each device, and can also control charging and discharging when abnormal heat is generated, and calculate and correct the remaining capacity of the battery pack 300. The lithium-ion battery 1 of the present invention can be applied to the batteries that make up the assembled battery 301.

[0065] When charging the battery pack 300, the positive terminal 321 and the negative terminal 322 are connected to the positive terminal and the negative terminal of a charger, respectively, for charging. When using an electronic device connected to the battery pack 300, the positive terminal 321 and the negative terminal 322 are connected to the positive terminal and the negative terminal of the electronic device, respectively, for discharging.

[0066] The battery pack 301 is made up of a plurality of secondary batteries 301a connected in series and / or parallel. In Fig. 9, six secondary batteries 301a are connected in a two-in-three-in-series (2P3S) configuration, but any connection method may be used.

[0067] The temperature detection unit 318 is connected to the temperature detection element 308 (e.g., a thermistor), measures the temperature of the battery assembly 301 or the battery pack 300, and supplies the measured temperature to the control unit 310. The voltage detection unit 311 measures the voltage of the battery assembly 301 and each secondary battery 301a that constitutes it, A / D converts the measured voltage, and supplies it to the control unit 310. The current measurement unit 313 measures the current using the current detection resistor 307, and supplies the measured current to the control unit 310.

[0068] Switch control unit 314 controls charge control switch 302a and discharge control switch 303a of switch unit 304 based on the voltage and current input from voltage detection unit 311 and current measurement unit 313. When the voltage of any one of secondary batteries 301a falls below the overcharge detection voltage or overdischarge detection voltage, or when a large current suddenly flows, switch control unit 314 sends an OFF control signal to switch unit 304 to prevent overcharge, overdischarge, and overcurrent charging / discharging. Here, when the secondary battery is a lithium-ion secondary battery, the overcharge detection voltage is set to, for example, 4.20 V±0.05 V, and the overdischarge detection voltage is set to, for example, 2.4 V±0.1 V.

[0069] After the charge control switch 302a or the discharge control switch 303a is turned OFF, charging or discharging is possible only via the diode 302b or the diode 303b. These charge / discharge switches can be semiconductor switches such as MOSFETs. In this case, the parasitic diodes of the MOSFETs function as the diodes 302b and 303b. Although the switch unit 304 is provided on the positive side in FIG. 9, it may also be provided on the negative side.

[0070] The memory 317 stores in advance numerical values calculated by the control unit 310, the battery characteristics of each secondary battery 301a in its initial state measured during the manufacturing process, and the like, and can be rewritten as needed. Also, by storing the full charge capacity of the secondary battery 301a, the memory 317 can calculate the remaining capacity in cooperation with the control unit 310.

[0071] (2)Electronic equipment The secondary batteries according to the above-described embodiments or examples of the present invention can be mounted in devices such as electronic devices, electric transport devices, and power storage devices, and can be used to supply power.

[0072] Examples of electronic devices include laptop computers, smartphones, tablet devices, PDAs (personal digital assistants), mobile phones, wearable devices, video camcorders, digital still cameras, e-books, music players, headphones, game consoles, pacemakers, hearing aids, power tools, televisions, lighting equipment, toys, medical equipment, and robots. Furthermore, electric transport equipment, power storage devices, power tools, and electric unmanned aerial vehicles, which will be described later, can also be included in the category of electronic devices in a broad sense.

[0073] Examples of electric transportation devices include electric vehicles (including hybrid vehicles), electric motorcycles, electrically assisted bicycles, electric buses, electric carts, automated guided vehicles (AGVs), and railroad cars. Electric passenger aircraft and unmanned electric aircraft for transportation are also included. The secondary battery according to the present invention can be used not only as a driving power source for these devices, but also as an auxiliary power source and a power source for energy regeneration.

[0074] Examples of the power storage device include commercial or home power storage modules, and power storage power sources for buildings such as houses, buildings, and offices, or for power generation facilities.

[0075] (3) Power tools An example of an electric screwdriver as a power tool to which the present invention can be applied will be described briefly with reference to Fig. 10. An electric screwdriver 431 is provided with a motor 433 that transmits rotational power to a shaft 434, and a trigger switch 432 that is operated by the user. By operating the trigger switch 432, a screw or the like is driven into an object by the shaft 434.

[0076] A battery pack 430 and a motor control unit 435 are housed in a housing below the handle of the electric screwdriver 431. The battery pack 300 described above can be used as the battery pack 430. The battery pack 430 is either built into the electric screwdriver 431 or is detachable. The battery pack 430 can be attached to a charging device while built into the electric screwdriver 431 or detached. The lithium ion battery 1 of the present invention can be used as the battery included in the battery pack 430.

[0077] Each of the battery pack 430 and the motor control unit 435 is equipped with a microcomputer. Power is supplied from the battery pack 430 to the motor control unit 435, and charge / discharge information for the battery pack 430 is communicated between the two microcomputers. The motor control unit 435 controls the rotation / stop and rotation direction of the motor 433, and can also cut off the power supply to the load (such as the motor 433) in the event of over-discharge.

[0078] (4) Energy storage system for electric vehicles As an example of applying the present invention to a power storage system for an electrically powered vehicle, a configuration example of a hybrid vehicle (HV) employing a series hybrid system is shown schematically in Figure 11. A series hybrid system is a vehicle that runs on an electric power driving force conversion device using electric power generated by a generator powered by an engine, or electric power that is temporarily stored in a battery.

[0079] This hybrid vehicle 600 is equipped with an engine 601, a generator 602, an electric power driving force conversion device 603 (a DC motor or an AC motor; hereinafter simply referred to as "motor 603"), drive wheels 604a, 604b, wheels 605a, 605b, a battery 608, a vehicle control device 609, various sensors 610, and a charging port 611. The battery 1 of the present invention described above or a power storage module equipped with a plurality of batteries 1 of the present invention can be applied to the battery 608. The secondary battery may be cylindrical, rectangular, or laminated. The lithium-ion battery 1 of the present invention can be applied to the battery included in the battery 608.

[0080] The motor 603 is operated by power from the battery 608, and the rotational force of the motor 603 is transmitted to drive wheels 604a and 604b. The rotational force of the engine 601 is transmitted to the generator 602, and the power generated by the generator 602 using the rotational force can be stored in the battery 608. Various sensors 610 control the engine rotation speed via the vehicle control device 609 and control the opening of a throttle valve (not shown). The various sensors 610 include a speed sensor, an acceleration sensor, an engine rotation speed sensor, etc.

[0081] When hybrid vehicle 600 is decelerated by a braking mechanism (not shown), the resistance force generated during deceleration is applied to motor 603 as a rotational force, and regenerative power generated by this rotational force is stored in battery 608. Although not shown, an information processing device (for example, a battery remaining capacity display device) that processes information related to vehicle control based on information about the secondary battery may also be provided. Battery 608 can receive and store power by being connected to an external power source via a charging port 611 of hybrid vehicle 600. Such an HV vehicle is called a plug-in hybrid vehicle (PHV or PHEV).

[0082] Although the above description has been given using a series hybrid vehicle as an example, the present invention can also be applied to a parallel hybrid vehicle that uses both an engine and a motor, or a hybrid vehicle that combines a series and parallel hybrid system.Furthermore, the present invention can also be applied to an electric vehicle (EV or BEV) that runs only on a drive motor without an engine, and a fuel cell vehicle (FCV). [Explanation of symbols]

[0083] 1···Lithium ion battery, 12, 13··Insulating plate, 21··Positive electrode, 22···Negative electrode, 23··Separator, 24···Center pin, 25···Positive electrode lead, 26···Negative electrode lead, 41···Insulating layer, 51···Top of crimp, 52···Flange surface, 53···Terminal portion, 54···Side portion of battery can, 55···Tip portion of battery can, 56···Neck portion

Claims

1. an electrode winding body having a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound with a separator interposed therebetween; a battery can containing the electrode winding body and having a crimp portion; a battery lid having a flange portion; a gasket disposed between the inside of the crimp portion of the battery can and the flange portion of the battery lid; and the gasket has a gasket surface exposed to the outside from a tip end of the crimp portion, an insulating layer is applied from the top of the crimped portion to at least a portion of the gasket surface; The material of the battery lid contains iron, the insulating layer is made of a fluororesin, and the thickness of the insulating layer is 20 μm or more and 49 μm or less; The insulating layer is disposed so that a portion of the gasket is exposed.

2. an electrode winding body having a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound with a separator interposed therebetween; a battery can containing the electrode winding body and having a crimp portion; a battery lid having a flange portion; a gasket disposed between the inside of the crimp portion of the battery can and the flange portion of the battery lid; and the gasket has a gasket surface exposed to the outside from a tip end of the crimp portion, an insulating layer is applied from the top of the crimped portion to at least a portion of the gasket surface; The material of the battery lid contains iron, the insulating layer is made of a fluororesin, and the thickness of the insulating layer is 20 μm or more and 49 μm or less; The insulating layer covers substantially the entire exposed surface of the flange portion so as not to cover any surfaces rising in the vertical direction on the exposed surface of the flange portion. Secondary battery.

3. 2. The secondary battery according to claim 1, further comprising an insulating layer covering the area from the top of the crimped portion to the side surface of the battery can.

4. 4. The secondary battery according to claim 1, wherein the insulating layer contains a fluorescent agent.

5. The positive electrode has a positive electrode active material layer on both sides of a strip-shaped positive electrode foil, 5. The secondary battery according to claim 1, wherein the positive electrode active material layer contains a material having an olivine-type crystal structure.

6. the battery can has a first polarity; the battery lid has a second polarity; 6. The secondary battery according to claim 1, wherein the first polarity is a negative electrode and the second polarity is a positive electrode.

7. 7. An electronic device comprising the secondary battery according to claim 1.

8. A power tool comprising the secondary battery according to any one of claims 1 to 6.

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