Secondary batteries, battery packs, electronic devices, electric tools, electric aircraft, and electric vehicles

Abstract

A secondary battery comprises an electrode winding body with a winding structure, a positive electrode collector plate and a negative electrode collector plate housed in an outer can, in which the positive electrode has a covering portion covered by a positive electrode active material layer and a positive electrode active material non-covering portion on a strip-shaped positive electrode foil, and the negative electrode has a covering portion covered by a negative electrode active material layer and a negative electrode active material non-covering portion on a strip-shaped negative electrode foil, the positive electrode active material non-covering portion is joined to the positive electrode collector plate at one end of the electrode winding body, and the negative electrode active material non-covering portion is joined to the negative electrode collector plate at the other end of the electrode winding body, either or both of the positive electrode active material non-covering portion and the negative electrode active material non-covering portion have a flat surface formed by bending toward the central axis of the winding structure and overlapping, the flat surface has a groove passing through the central axis and a groove not passing through the central axis, and the portion of the flat surface that does not have a groove passing through the central axis and a groove that does not pass through the central axis is joined to the positive electrode collector plate or the negative electrode collector plate.

Description

Technical Field

[0001] The present invention relates to a secondary battery, a battery pack, an electronic device, an electric tool, an electric aircraft and an electric vehicle. Background Art

[0002] The use of lithium-ion batteries in the fields of automobiles and machinery has expanded, so high-output batteries are needed. As one of the methods for producing this high output, high-rate discharge has been proposed. High-rate discharge is a discharge in which a relatively large current flows. At this time, the size of the internal resistance of the battery becomes a problem. As the internal resistance of the battery, for example, the contact resistance between the positive electrode foil, the negative electrode foil and the collector plate for extracting the current can be listed.

[0003] For example, Patent Document 1 describes a cylindrical lithium-ion secondary battery having a structure and a method for manufacturing a battery with reduced internal resistance and excellent high-rate discharge characteristics compared to the past. In the technology described in Patent Document 1, at the end of a vortex electrode body formed by winding a positive electrode plate and a negative electrode plate coated with an active material on a current collector of a strip electrode through a separator, there is an exposed portion of the current collector that is not coated with an active material. By pre-arranging 8 radial bending auxiliary grooves at the end, the generation of wrinkles can be suppressed during the tapping process, and the welding of the exposed portion of the current collector and the current collector plate can be reliably performed.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2008-166030

[0007] However, in the technology described in Patent Document 1, since eight bending auxiliary grooves are radially arranged from the outer edge of the vortex electrode body toward the center axis, there is a problem that the welding area between the exposed portion of the collector and the collector plate is reduced near the center axis of the vortex electrode body, and the internal resistance cannot be reduced.

[0008] Therefore, one object of the present invention is to provide a battery having a tank having a shape that can reduce the internal resistance of the battery. Summary of the invention

[0009] In order to solve the above-mentioned problems, the present invention is a secondary battery in which an electrode winding body, a positive electrode collector plate and a negative electrode collector plate are accommodated in an outer can, and the electrode winding body has a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound with a separator interposed therebetween.

[0010] The positive electrode has a strip-shaped positive electrode foil having a covered portion covered with a positive electrode active material layer and a positive electrode active material non-covered portion.

[0011] The negative electrode has a strip-shaped negative electrode foil having a covered portion covered with a negative electrode active material layer and a negative electrode active material non-covered portion.

[0012] The positive electrode active material non-covered portion is joined to the positive electrode current collector plate at one end of the electrode winding body, and the negative electrode active material non-covered portion is joined to the negative electrode current collector plate at the other end of the electrode winding body.

[0013] One or both of the positive electrode active material non-covered portion and the negative electrode active material non-covered portion have flat surfaces formed by bending toward the central axis of the wound structure and overlapping each other.

[0014] The flat surface has grooves that pass through the central axis and grooves that do not pass through the central axis.

[0015] The portion of the flat surface that does not have the two grooves, that is, the portion that does not have the groove that passes through the central axis and the groove that does not pass through the central axis is joined to the positive electrode current collector plate or the negative electrode current collector plate.

[0016] In addition, the present invention is a battery pack having:

[0017] The above secondary battery;

[0018] a control unit that controls the secondary battery; and

[0019] The outer casing contains a secondary battery.

[0020] The present invention is an electronic device having the secondary battery or the battery pack.

[0021] The present invention is an electric tool having the above-mentioned battery pack and using the battery pack as a power source.

[0022] The present invention is an electric aircraft having:

[0023] The above-mentioned battery pack;

[0024] a plurality of rotating blades;

[0025] a motor, respectively rotating the rotary blades;

[0026] A supporting shaft, supporting the rotating blades and the motor respectively;

[0027] a motor control unit that controls the rotation of the motor; and

[0028] Power supply line, supplying power to the motor,

[0029] The battery pack is connected to the power supply line.

[0030] The present invention is an electric vehicle having the above-mentioned secondary battery and comprising:

[0031] a conversion device that receives power supplied from the secondary battery and converts the power into a driving force for the vehicle; and

[0032] The control device performs information processing related to vehicle control based on information related to the secondary battery.

[0033] According to at least one embodiment of the present invention, the internal resistance of the battery can be reduced, and a high-output battery can be realized. It should be noted that the content of the present invention is not limited to the effects exemplified in this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic cross-sectional view of a battery according to one embodiment.

[0035] Figure 2 This is a diagram for explaining an example of the arrangement relationship among the positive electrode, the negative electrode, and the separator in the electrode wound body.

[0036] Figure 3 A in the middle is a top view of the positive electrode collector plate. Figure 3 B is a top view of the negative electrode collector plate.

[0037] Figure 4 Middle A~ Figure 4 FIG. 5 is a diagram for explaining an assembly process of a battery according to an embodiment.

[0038] Figure 5 Middle A and Figure 5 B is a diagram showing Example 1.

[0039] Figure 6 Middle A and Figure 6 B is a diagram showing Example 2.

[0040] Figure 7 Middle A and Figure 7 B is a diagram showing Comparative Example 1.

[0041] Figure 8 Middle A and Figure 8 B is a diagram showing Comparative Example 2.

[0042] Fig. 9 Middle A and Fig. 9 B is a diagram showing Comparative Example 3.

[0043] Fig.10 Middle A and Fig.10 B is a diagram showing Comparative Example 4.

[0044] Fig.11 Middle A and Fig.11 B is a diagram showing Comparative Example 5.

[0045] Fig.12Middle A~ Fig.12 D in the figure is a diagram showing an example of a slot.

[0046] Fig.13 It is a connection diagram for explaining a battery pack as an application example of the present invention.

[0047] Fig.14 It is a connection diagram for explaining an electric power tool as an application example of the present invention.

[0048] Fig.15 It is a connection diagram for explaining an unmanned aerial vehicle as an application example of the present invention.

[0049] Fig.16 This is a connection diagram used in describing an electric vehicle as an application example of the present invention. DETAILED DESCRIPTION

[0050] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the order of the description is as follows.

[0051] <1. One embodiment>

[0052] <2. Modifications>

[0053] <3. Application examples>

[0054] The embodiments and the like described below are preferred specific examples of the present invention, and the contents of the present invention are not limited to these embodiments and the like.

[0055] In the embodiment of the present invention, a cylindrical lithium ion battery is used as an example of a secondary battery. Of course, other batteries other than lithium ion batteries or batteries other than cylindrical batteries can also be used. It can also be applied to Li-S batteries (lithium-sulfur secondary batteries).

[0056] <1. One embodiment>

[0057] First, the overall structure of a lithium-ion battery will be described. Figure 1 1 is a schematic cross-sectional view of a lithium ion battery 1. The lithium ion battery 1 is, for example, Figure 1 1 , a cylindrical lithium ion battery 1 is shown in which an electrode winding body 20 is accommodated in an outer can 11 .

[0058] Specifically, the lithium ion battery 1 includes, for example, a pair of insulating plates 12 and 13 and an electrode winding 20 inside a cylindrical outer can 11. In addition, the lithium ion battery 1 may include, for example, any one or more of a thermistor (PTC) element and a reinforcing member inside the outer can 11.

[0059] [Outer can]

[0060] The outer can 11 is mainly a component for storing the electrode winding body 20. The outer can is, for example, a cylindrical container with one end open and the other end closed. That is, the outer can 11 has an open end (open end 11N). The outer can 11 contains, for example, any one or two or more metal materials such as iron, aluminum, and alloys thereof. In addition, the surface of the outer can 11 may be plated with, for example, any one or two or more metal materials such as nickel.

[0061] [Insulation board]

[0062] Insulating plates 12, 13 are, for example, disk-shaped plates each having a surface perpendicular to the winding axis of electrode winding 20, that is, perpendicular to the winding axis of electrode winding 20. Figure 1 In addition, the insulating plates 12 and 13 are arranged, for example, so as to sandwich the electrode wound body 20 therebetween.

[0063] [Riveted structure]

[0064] At the open end 11N of the outer can 11, for example, the battery cover 14 and the safety valve mechanism 30 are riveted via the gasket 15. The battery cover 14 is a "cover member" of one embodiment of the present invention, and the gasket 15 is a "sealing member" of one embodiment of the present invention. Thus, the outer can 11 is sealed in a state where the electrode winding body 20 and the like are accommodated inside the outer can 11. Therefore, a structure (riveted structure 11R) in which the battery cover 14 and the safety valve mechanism 30 are riveted via the gasket 15 is formed at the open end 11N of the outer can 11. That is, the bent portion 11P is a so-called curled portion, and the riveted structure 11R is a so-called curled structure.

[0065] [Battery cover]

[0066] The battery cover 14 is a member that closes the open end 11N of the outer can 11, mainly in a state where the electrode winding body 20 and the like are stored inside the outer can 11. The battery cover 14 is made of, for example, the same material as the outer can 11. The central region of the battery cover 14 protrudes, for example, in the +Z direction. As a result, the region (peripheral region) other than the central region of the battery cover 14 contacts, for example, the safety valve mechanism 30.

[0067] [washer]

[0068] The gasket 15 is mainly a member that seals the gap between the bent portion 11P and the battery cover 14 by being interposed between the exterior can 11 (bent portion 11P) and the battery cover 14. The surface of the gasket 15 may be coated with asphalt or the like, for example.

[0069] The gasket 15 includes, for example, any one or more of insulating materials. The type of insulating material is not particularly limited, and examples thereof include polymer materials such as polybutylene terephthalate (PBT) and polypropylene (PP). Among them, the insulating material is preferably polybutylene terephthalate. This is because the gap between the bent portion 11P and the battery cover 14 is fully sealed while the outer can 11 and the battery cover 14 are electrically separated from each other.

[0070] [Safety valve mechanism]

[0071] The safety valve mechanism 30 releases the internal pressure of the outer tank 11 by releasing the sealing state of the outer tank 11 as needed when the internal pressure (internal pressure) of the outer tank 11 increases. The internal pressure of the outer tank 11 increases due to, for example, gas generated by decomposition reaction of the electrolyte during charge and discharge.

[0072] [Electrode winding body]

[0073] In a cylindrical lithium-ion battery, a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are wound into a spiral shape with a separator 23 sandwiched therebetween, and are housed in an outer can 11 in a state of being impregnated with an electrolyte. The positive electrode 21 is formed by forming a positive electrode active material layer 21B on one or both sides of a positive electrode foil 21A, and the material of the positive electrode foil 21A is, for example, a metal foil made of aluminum or an aluminum alloy. The negative electrode 22 is formed by forming a negative electrode active material layer 22B on one or both sides of a negative electrode foil 22A, and the material of the negative electrode foil 22A is, for example, a metal foil made of nickel, a nickel alloy, copper or a copper alloy. The separator 23 is a porous and insulating film that electrically insulates the positive electrode 21 and the negative electrode 22 and allows substances such as ions or electrolytes to move.

[0074] The positive electrode active material layer 21B and the negative electrode active material layer 22B cover most of the positive electrode foil 21A and the negative electrode foil 22A, respectively, but do not intentionally cover the periphery of one end in the short axis direction of the strip. Hereinafter, the portion not covered by the active material layer 21B, 22B is appropriately referred to as the active material non-covered portion. In a cylindrical battery, the electrode winding body 20 is overlapped and wound with the separator 23 interposed therebetween so that the active material non-covered portion 21C of the positive electrode and the active material non-covered portion 22C of the negative electrode face in opposite directions.

[0075] Figure 2 FIG. 2 shows an example of a structure before winding, in which the positive electrode 21, the negative electrode 22 and the separator 23 are stacked. The active material non-covered portion 21C of the positive electrode ( Figure 2 The width of the oblique line portion on the upper side of the negative electrode is A, and the negative electrode active material non-covered portion 22C ( Figure 2The width of the oblique line portion on the lower side of the separator 23 is B. In one embodiment, preferably A>B, for example, A=7(mm), B=4(mm). The length of the portion of the non-covered portion 21C of the positive electrode active material protruding from one end in the width direction of the separator 23 is C, and the length of the portion of the non-covered portion 22C of the negative electrode active material protruding from the other end in the width direction of the separator 23 is D. In one embodiment, preferably C>D, for example, C=4.5(mm), D=3(mm).

[0076] The non-covered active material portion 21C of the positive electrode is composed of, for example, aluminum, and the non-covered active material portion 22C of the negative electrode is composed of, for example, copper, and in general, the non-covered active material portion 21C of the positive electrode is softer (Young's modulus is low) than the non-covered active material portion 22C of the negative electrode. Therefore, in one embodiment, A>B and C>D are more preferably, in which case, when the non-covered active material portion 21C of the positive electrode and the non-covered active material portion 22C of the negative electrode are bent at the same pressure from both sides, the height of the bent portion measured from the front end of the separator 23 is sometimes approximately the same in the positive electrode 21 and the negative electrode 22. At this time, the non-covered active material portions 21C and 22C are bent and overlap appropriately, so that the non-covered active material portions 21C and 22C can be easily joined to the collector plates 24 and 25 by laser welding. Joining in one embodiment refers to connection by laser welding, but the joining method is not limited to laser welding.

[0077] In the positive electrode 21, a region with a width of 3 mm including the boundary between the active material non-covered portion 21C and the active material covered portion 21B is surrounded by the insulating layer 101 ( Figure 2 The insulating layer 101 covers the entire area of ​​the active material non-covered portion 21C of the positive electrode that is opposite to the active material covered portion 22B of the negative electrode via the separator. The insulating layer 101 has the effect of reliably preventing an internal short circuit of the battery 1 when foreign matter invades between the active material covered portion 22B of the negative electrode and the active material non-covered portion 21C of the positive electrode. In addition, the insulating layer 101 has the effect of absorbing the impact when an impact is applied to the battery 1, and reliably preventing the active material non-covered portion 21C of the positive electrode from bending or short-circuiting with the negative electrode 22.

[0078] A through hole 26 is formed on the central axis of the electrode winding body 20. The through hole 26 is a hole for inserting the winding core for assembling the electrode winding body 20 and the electrode rod for welding. Since the electrode winding body 20 is formed by overlapping and winding the active material non-covered portion 21C of the positive electrode and the active material non-covered portion 22C of the negative electrode in opposite directions, the active material non-covered portion 21C of the positive electrode is concentrated on one end of the electrode winding body (end 41), and the active material non-covered portion 22C of the negative electrode is concentrated on the other end of the electrode winding body 20 (end 42). In order to make good contact with the collector plates 24 and 25 for extracting current, the active material non-covered portions 21C and 22C are bent, and the ends 41 and 42 become flat surfaces. The bending direction is from the outer edge portions 27 and 28 of the ends 41 and 42 toward the through hole 26, and the active material non-covered portions on the adjacent circumferences overlap each other in the wound state and are bent. It should be noted that in this specification, the term “flat surface” includes not only a completely flat surface but also a surface having some irregularities or surface roughness to the extent that the active material non-covered portion and the current collector plate can be bonded.

[0079] By bending the active material non-covered portions 21C and 22C so that they overlap, the ends 41 and 42 may appear to be flat surfaces at first glance. However, if no processing is performed before bending, wrinkles or gaps (gaps, spaces) will be generated at the ends 41 and 42 during bending, and the ends 41 and 42 will not be flat surfaces. Here, "wrinkles" or "gaps" refer to the portions of the active material non-covered portions 21C and 22C that are offset when bent, and the ends 41 and 42 will not be flat surfaces. In order to prevent the generation of wrinkles or gaps, grooves 43 and 44 are pre-formed in the radial direction from the through hole 26 (for example, see Figure 4 B). The central axis of the electrode winding body 20 has a through hole 26, and the grooves include a groove 43 passing through the central axis and a groove 44 not passing through the central axis. The groove 43 passing through the central axis is a groove extending from the outer edge portion 27, 28 of the end portion 41, 42 to the through hole 26 having the central axis, and the groove 44 not passing through the central axis is a groove located at the outer periphery and does not extend to the through hole 26. There are cutouts in the active material non-covered portions 21C, 22C located near the through hole 26 where the winding of the positive electrode 21 and the negative electrode 22 starts. This is to prevent the through hole 26 from being blocked when bending toward the through hole 26. The grooves 43, 44 remain in the flat surface even after the active material non-covered portions 21C, 22C are bent, and the portion without the grooves 43, 44 is joined (welded, etc.) to the positive electrode collector plate 24 or the negative electrode collector plate 25. It should be noted that not only the flat surface but also the grooves 43, 44 can be joined to a portion of the collector plates 24, 25.

[0080] The detailed structure of the electrode wound body 20 , that is, the detailed structures of the positive electrode 21 , the negative electrode 22 , the separator 23 , and the electrolyte solution will be described later.

[0081] [Current collector]

[0082] In a conventional lithium-ion battery, for example, a lead for extracting current is welded to each part of the positive electrode and the negative electrode, so that the internal resistance of the battery is large, and the lithium-ion battery generates heat and reaches a high temperature during discharge, and is therefore not suitable for high-rate discharge. Therefore, in a lithium-ion battery of one embodiment, by arranging a positive electrode collector plate 24 and a negative electrode collector plate 25 at the ends 41 and 42 and performing multi-point welding with the active material non-covered parts 21C and 22C of the positive or negative electrode present at the ends 41 and 42, the internal resistance of the battery is suppressed to a low level. Bending the ends 41 and 42 to form a flat surface also contributes to low resistance.

[0083] Figure 3 Middle A and Figure 3 B represents an example of a current collector plate. Figure 3 A is the positive electrode collector plate 24, Figure 3 B is the negative electrode collector plate 25. The material of the positive electrode collector plate 24 is, for example, a metal plate made of a single body or a composite material of aluminum or aluminum alloy, and the material of the negative electrode collector plate 25 is, for example, a metal plate made of a single body or a composite material of nickel, nickel alloy, copper or copper alloy. Figure 3 As shown in A, the positive electrode current collector plate 24 has a flat sector-shaped fan-shaped portion 31 with a rectangular strip-shaped portion 32. A hole 35 is formed near the center of the fan-shaped portion 31, and the position of the hole 35 corresponds to the position of the through hole 26.

[0084] Figure 3 The portion indicated by the oblique lines in A is an insulating portion 32A on which an insulating tape or an insulating material is pasted on the strip portion 32. Figure 3 The portion below the oblique line portion of A is the connection portion 32 B connected to the sealing plate that also serves as an external terminal. It should be noted that in the case of a battery structure in which a metal center pin (not shown) is not provided in the through hole 26, the possibility of the strip portion 32 contacting the portion of the negative electrode potential is low, so there may be no insulating portion 32A. In this case, the charge and discharge capacity can be increased by increasing the width of the positive electrode 21 and the negative electrode 22 by an amount equivalent to the thickness of the insulating portion 32A.

[0085] The shape of the negative electrode current collector plate 25 is substantially the same as that of the positive electrode current collector plate 24 , but the strip-shaped portion is different. Figure 3The strip portion 34 of the negative electrode collector plate of B is shorter than the strip portion 32 of the positive electrode collector plate, and does not have a portion corresponding to the insulating portion 32A. There are a plurality of circular protrusions (protrusions) 37 represented by circles on the strip portion 34. During resistance welding, the current is concentrated on the protrusions, the protrusions melt, and the strip portion 34 is welded to the bottom of the outer can 11. Similar to the positive electrode collector plate 24, a hole 36 is opened near the center of the fan-shaped portion 33 of the negative electrode collector plate 25, and the position of the hole 36 is a position corresponding to the through hole 26. Since the fan-shaped portion 31 of the positive electrode collector plate 24 and the fan-shaped portion 33 of the negative electrode collector plate 25 are fan-shaped, a portion of the end portions 41 and 42 is covered. The reason for not covering the entirety is to allow the electrolyte to penetrate smoothly into the electrode winding body when assembling the battery, or to facilitate the release of the gas generated when the battery becomes abnormally high temperature or overcharged to the outside of the battery.

[0086] [positive electrode]

[0087] The positive electrode active material layer 21B contains any one or more of positive electrode materials capable of inserting and removing lithium as positive electrode active materials. In addition, the positive electrode active material layer 21B may further contain any one or more of other materials such as a positive electrode binder and a positive electrode conductor. The positive electrode material is preferably a lithium-containing compound, more specifically, preferably a lithium-containing composite oxide and a lithium-containing phosphate compound.

[0088] A lithium-containing composite oxide is an oxide containing lithium and one or more other elements (elements other than lithium) as constituent elements, and has, for example, a crystal structure of a layered rock salt type or a spinel type. A lithium-containing phosphate compound is a phosphate compound containing lithium and one or more other elements as constituent elements, and has, for example, a crystal structure of an olivine type.

[0089] The positive electrode binder includes, for example, any one or more of synthetic rubber and polymer compounds, etc. Synthetic rubber includes, for example, styrene butadiene rubber, fluorine rubber, and ethylene propylene diene rubber, etc. Polymer compounds include, for example, polyvinylidene fluoride and polyimide, etc.

[0090] The positive electrode conductive agent includes, for example, any one or more of carbon materials, etc. The carbon material is, for example, graphite, carbon black, acetylene black, Ketjen black, etc. In addition, the positive electrode conductive agent may also be a metal material, a conductive polymer, etc., as long as it is a conductive material.

[0091] [negative electrode]

[0092] The surface of the negative electrode foil 22A is preferably roughened. This is because the adhesion of the negative electrode active material layer 22B to the negative electrode foil 22A is improved by the so-called anchoring effect. In this case, the surface of the negative electrode foil 22A can be roughened at least in the area opposite to the negative electrode active material layer 22B. The roughening method is, for example, a method of forming microparticles by electrolytic treatment. In the electrolytic treatment, since microparticles are formed on the surface of the negative electrode foil 22A by electrolysis in an electrolytic cell, concavoconvexity is provided on the surface of the negative electrode foil 22A. Copper foil produced by electrolysis is generally referred to as electrolytic copper foil.

[0093] The negative electrode active material layer 22B contains any one or two or more negative electrode materials capable of inserting and removing lithium as negative electrode active materials. In addition, the negative electrode active material layer 22B may further contain any one or two or more other materials such as a negative electrode binder and a negative electrode conductor.

[0094] The negative electrode material is, for example, a carbon material. This is because the change in the crystal structure is very small when lithium is inserted and released, so a high energy density can be stably obtained. In addition, the carbon material also functions as a negative electrode conductive agent, so the conductivity of the negative electrode active material layer 22B is improved.

[0095] Carbon materials include, for example, graphitizable carbon, difficult graphitizable carbon, and graphite. In addition, the interplanar spacing of the (002) plane in the difficult graphitizable carbon is preferably greater than 0.37 nm, and the interplanar spacing of the (002) plane in the graphite is preferably less than 0.34 nm. More specifically, carbon materials include, for example, pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound sintered bodies, activated carbon, and carbon black. The cokes include pitch coke, needle coke, and petroleum coke. The organic polymer compound sintered body is a sintered product of polymer compounds such as phenolic resins and furan resins sintered (carbonized) at an appropriate temperature. In addition, the carbon material may be low-crystalline carbon that has been heat-treated at a temperature below about 1000°C, or it may be amorphous carbon. It should be noted that the shape of the carbon material may be any one of fibrous, spherical, granular, and flaky.

[0096] In the lithium ion battery 1, when the open circuit voltage (i.e., the battery voltage) is 4.25 V or more when fully charged, the amount of lithium deintercalation per unit mass increases compared to the case where the open circuit voltage is 4.20 V when fully charged, even if the same positive electrode active material is used, and the amount of the positive electrode active material and the negative electrode active material is adjusted accordingly. Thus, a high energy density can be obtained.

[0097] [Diaphragm]

[0098] The separator 23 is disposed between the positive electrode 21 and the negative electrode 22, and allows lithium ions to pass through while preventing a current short circuit caused by the contact between the positive electrode 21 and the negative electrode 22. The separator 23 can be, for example, any one or two or more porous films such as synthetic resins and ceramics, or a laminated film of two or more porous films. Synthetic resins are, for example, polytetrafluoroethylene, polypropylene, and polyethylene.

[0099] In particular, the separator 23 may include, for example, the above-mentioned porous film (substrate layer) and a polymer compound layer provided on one or both surfaces of the substrate layer. This is because the adhesion of the separator 23 to the positive electrode 21 and the negative electrode 22 is improved, respectively, so that deformation of the electrode winding body 20 can be suppressed. As a result, the decomposition reaction of the electrolyte can be suppressed, and the leakage of the electrolyte impregnated in the substrate layer can also be suppressed, so that even if charging and discharging are repeated, the resistance is not easy to increase, and the battery expansion can be suppressed.

[0100] The polymer compound layer includes, for example, polymer compounds such as polyvinylidene fluoride. This is because the physical strength is excellent and the electrochemical stability is stable. In addition, the polymer compound may also be a compound other than polyvinylidene fluoride. In the case of forming the polymer compound layer, for example, a solution in which the polymer compound is dissolved in an organic solvent is applied to the substrate layer, and then the substrate layer is dried. It should be noted that the substrate layer may also be dried after being immersed in the solution. The polymer compound layer may contain, for example, any one or more of insulating particles such as inorganic particles. Examples of the types of inorganic particles are aluminum oxide and aluminum nitride.

[0101] [Electrolyte]

[0102] The electrolyte solution contains a solvent and an electrolyte salt. In addition, the electrolyte solution may also contain any one or two or more other materials such as additives.

[0103] The solvent includes any one or two or more of non-aqueous solvents such as organic solvents. The electrolyte solution including the non-aqueous solvent is a so-called non-aqueous electrolyte solution.

[0104] Examples of the non-aqueous solvent include cyclic carbonates, chain carbonates, lactones, chain carboxylates, and nitriles (mononitriles).

[0105] The electrolyte salt includes, for example, any one or more of salts such as lithium salts. In addition, the electrolyte salt may also include, for example, salts other than lithium salts. The salts other than lithium are, for example, salts of light metals other than lithium.

[0106] Lithium salts include, for example, lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetraphenylborate (LiB(C6H5)4), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), lithium tetrachloroaluminate (LiAlCl4), lithium hexafluorosilicate (Li2SF6), lithium chloride (LiCl) and lithium bromide (LiBr).

[0107] Among them, any one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluoroarsenate are preferred, and lithium hexafluorophosphate is more preferred. 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.

[0108] [Method for manufacturing lithium-ion battery]

[0109] Reference Figure 4 Middle A~ Figure 4 In F, a method for manufacturing a lithium-ion battery 1 according to one embodiment is described. First, a positive electrode active material is coated on the surface of a strip-shaped positive electrode foil 21A, which is used as a covering portion of the positive electrode 21, and a negative electrode active material is coated on the surface of a strip-shaped negative electrode foil 22A, which is used as a covering portion of the negative electrode 22. At this time, active material non-covered portions 21C and 22C are made at one end of the short side direction of the positive electrode 21 and one end of the short side direction of the negative electrode 22, where the positive electrode active material and the negative electrode active material are not coated. An incision is made in a portion of the active material non-covered portions 21C and 22C, which corresponds to the portion where winding starts during winding. The positive electrode 21 and the negative electrode 22 are subjected to processes such as drying. Then, the active material non-covered portion 21C of the positive electrode and the active material non-covered portion 22C of the negative electrode are overlapped in opposite directions via the separator 23 so that a through hole 26 is formed on the central axis, and the produced incision is arranged near the central axis, and wound into a spiral shape, thereby manufacturing. Figure 4 The electrode wound body 20 is as shown in FIG.

[0110] Then, if Figure 4 As shown in B, the ends of a relatively thin plate (for example, 0.5 mm thick) are pressed perpendicularly to the ends 41 and 42, and the ends 41 and 42 are partially bent to form grooves 43 and 44. In this way, grooves 43 passing through the central axis in the radial direction from the through hole 26 and grooves 44 not passing through the central axis are formed. Figure 4 The number and arrangement of the grooves 43 passing through the central axis and the grooves 44 not passing through the central axis shown in FIG. Figure 4As shown in C, the same pressure is applied to the ends 41 and 42 in a substantially vertical direction from both sides, and the non-covered active material portion 21C of the positive electrode and the non-covered active material portion 22C of the negative electrode are bent, and the ends 41 and 42 are formed into flat surfaces. At this time, pressure is applied in such a way that the non-covered active material portions at the ends 41 and 42 overlap and bend toward the through hole 26. Then, the fan-shaped portion 31 of the positive electrode collector plate 24 is laser welded at the end 41, and the fan-shaped portion 33 of the negative electrode collector plate 25 is laser welded at the end 42.

[0111] Then, if Figure 4 As shown in D, the strip portions 32 and 34 of the collector plates 24 and 25 are bent, and insulating plates 12 and 13 (or insulating tapes) are attached to the positive collector plates 24 and the negative collector plates 25. Figure 4 The electrode winding body 20 assembled as described above is inserted into the outer can 11 shown in E, and the bottom of the outer can 11 is welded. After the electrolyte is injected into the outer can 11, as shown in FIG. Figure 4 As shown in F, the gasket 15 and the battery cover 14 are used for sealing.

[0112] Example

[0113] The present invention will be specifically described below based on examples in which the differences in internal resistance are compared using the lithium ion batteries 1 produced as described above. It should be noted that the present invention is not limited to the examples described below.

[0114] [Examples 1 to 4]

[0115] The number of grooves 43 and 44 is changed to find the difference in internal resistance. For the end 41 of the positive electrode and the end 42 of the negative electrode, when the number of grooves 43 passing through the central axis is set to N1 and the number of grooves 44 not passing through the central axis is set to N2, N1 is set to 3 to 6 and N2 is set to 3 to 6. The two types of grooves 43 and 44 are arranged at approximately equal angles. The width of the positive electrode active material layer 21B is set to 59.0 (mm), and the width of the positive electrode 21 including the active material non-covered portion 21C is set to 66.0 (mm). The width of the negative electrode active material layer 22B is set to 62.0 (mm), and the width of the negative electrode 22 including the active material non-covered portion 22C is set to 66.0 (mm). The width of the separator 23 is set to 64.0 mm. The material of the positive electrode collector plate 24 is set to Al alloy, and the material of the negative electrode collector plate 25 is set to Cu alloy. The size of the battery is set to 21700 (diameter 21 (mm), length 70 (mm)). The portions of the ends 41 and 42 without the grooves 43 and 44 are laser welded to the positive electrode collector plate 24 or the negative electrode collector plate 25. L, D, F (see Fig.12A) As shown in Table 1. The thickness of the positive electrode collector plate was 0.2 (mm), the thickness of the positive electrode foil was 0.01 (mm), the thickness of the negative electrode collector plate was 0.08 (mm), and the thickness of the negative electrode foil was 0.01 (mm).

[0116] [Comparative Examples 1 to 5]

[0117] In the positive electrode 21 and the negative electrode 22, N1 is set to 3 to 8, N2 is set to 0 or 9, and the grooves 43 that do not pass through the central axis are arranged at substantially equal angles, L, D, F (see Fig.12 A) As shown in Table 1, other than this, it is the same as Examples 1 to 4.

[0118] [evaluate]

[0119] The battery was evaluated. The area of ​​the end portions 41 and 42 that overlapped with the positive electrode collector plate 24 or the negative electrode collector plate 25 and did not have grooves 43 and 44, wrinkles or gaps was taken as the weldable area. The number of points where the actual laser welding was successful was taken as the actual number of welding points. The internal resistance (DC resistance) of the battery was measured, and it was judged as OK if it was less than 10.5 (mΩ), and NG if it was not. The results are shown below.

[0120] [Table 1]

[0121]

[0122] The internal resistance of the example is a relatively low value of 10.5 (mΩ) or less (judged OK), while the internal resistance of the comparative example is a relatively high value of about 12 to 15 (mΩ) (judged NG). The weldable area of ​​the example is about 10% to 20% larger than that of the comparative example, and the actual number of weld points of the example is about twice that of the comparative example. Figure 5 to Figure 11 Indicates from Figure 1 This is an example of a diagram in which the end portions 41 and 42 are viewed in the Z-axis direction. Figure 5 Middle A and Figure 5 B corresponds to Example 1, Figure 6 Middle A and Figure 6 B corresponds to Example 2. Figure 7 Middle A and Figure 7 B corresponds to Comparative Example 1, Figure 8 Middle A and Figure 8 B corresponds to Comparative Example 2, Fig. 9 Middle A and Fig. 9 B corresponds to Comparative Example 3, Fig.10 Middle A and Fig.10 B corresponds to Comparative Example 4, Fig.11 Middle A and Fig.11 B corresponds to Comparative Example 5.

[0123] Figure 5 Middle A~ Fig.11 Middle A( Figure 5 to Figure 11 A) of each figure is a figure in which grooves 43 and 44 are provided and the ends 41 and 42 are bent on the plate surface or the like of the flat plate (equivalent to Figure 4 C before the current collector is provided), the blank area where the straight line or broken line is interrupted represents the part of the wrinkles or gaps 51 formed by the bending of the end portions 41 and 42 due to the lack of grooves 43 and 44. Figure 5 Middle B~ Fig.11 Medium B( Figure 5 to Figure 11 B) of each figure is respectively to install the collector plates 24 and 25 to Figure 5 Middle A~ Fig.11 Middle A( Figure 5 to Figure 11 A) of each figure on the surface of the end 41, 42 of the figure after. Figure 5 Middle B~ Fig.11 In FIG. 1B , the black circles indicate the areas 52 where the ends 41 , 42 are successfully welded to the collector plates 24 , 25 and where electrical contact exists, and the white circles indicate areas 53 where welding attempts were made but the welding failed due to wrinkles or gaps 51 at the ends 41 , 42 and where there is no electrical contact.

[0124] observe Figure 5 Middle B~ Fig.11 It can be seen from B that in Examples 1 and 2 ( Figure 5 Middle A, Figure 5 Middle B, Figure 6 Middle A, Figure 6 In the case of B), the ends 41 and 42 are flat surfaces, and there are many welding locations even near the central axis. Figure 7 Middle A, Figure 7 Middle B, Fig. 9 Middle A, Fig. 9 Middle B, Fig.10 Middle A, Fig.10 In the example B), the number of grooves 43 passing through the center axis and grooves 44 not passing through the center axis is insufficient, and wrinkles or gaps 51 are generated at the ends 41 and 42, so there are few weldable areas. Figure 8 Middle A, Figure 8 In the example B), the number of grooves 43 passing through the central axis is sufficient, and no wrinkles or gaps 51 are formed, but there are few weldable areas near the central axis of the electrode winding body 20, so there are few areas where welding is successful. Fig.11 Middle A, Fig.11As can be seen in B), since there are too many grooves 44 that do not pass through the central axis, there are fewer weldable parts on the electrode winding body 20. For these reasons, the internal resistance of the battery of the embodiment is lower than that of the comparative example. From the results in Table 1, it can be seen that when N1 is 3 or more and 6 or less, and N2 is N1 or more and 2×N1 or less, the internal resistance can be reduced.

[0125] [Examples 11 to 14]

[0126] The length of the groove 44 that does not pass through the center axis of the end portions 41 and 42 is changed to find the difference in internal resistance. The diameter of the through hole 26 is set to 4.2 (mm), and the diameter of the end portions 41 and 42 is set to 20.4 (mm). Fig.12 As shown in A, when the intersection of the groove 43 passing through the central axis and the outer edges 27 and 28 is set as U, and the other intersections of the groove 43 passing through the central axis and the outer edges 27 and 28 and the intersections adjacent to the intersection U on the outer edges 27 and 28 are set as U', the distance from the intersection V of the line segment UU' and the groove 44 not passing through the central axis along the groove 44 not passing through the central axis to the outer edges 27 and 28 is set as F (mm). The length of the groove 44 not passing through the central axis is set as L (mm). At this time, the straight-line distance from the front end of the inner circumference of the groove 44 not passing through the central axis to the peripheral edge of the through hole 26 is set as D (mm), and the distance from the outer edges 27 and 28 to the through hole 26 (the sum of L and D) is set to 8.1 (mm). The number (N1) of the grooves 43 passing through the central axis is set to 3 to 6, L is set to L ≥ 1.1 × F, and D is set to D ≥ 1.5 (mm). The number (N2) of the grooves 44 not passing through the central axis is equal to the number (N1) of the grooves 43 passing through the central axis, and the grooves 43 and the grooves 44 are alternately arranged at substantially equal angular intervals. Fig.12 A corresponds to Example 11, Fig.12 B corresponds to Example 12, Fig.12 C corresponds to Example 13, Fig.12 D corresponds to Example 14. Fig.12 In order to avoid complexity, A to 12D each show a groove 44 that does not pass through the central axis. Fig.12 B~ Fig.12 The positional relationship between L, F and D of D is not shown in the figure, but Fig.12A is the same. The thickness of the positive electrode collector plate is set to 0.2 (mm), the thickness of the positive electrode foil is set to 0.01 (mm), the thickness of the negative electrode collector plate is set to 0.08 (mm), and the thickness of the negative electrode foil is set to 0.01 (mm). The thickness of the positive electrode foil, the thickness of the negative electrode foil, the thickness of the positive electrode collector plate, and the thickness of the negative electrode collector plate are measured using a micrometer (MDC-25MX manufactured by Mitsutoyo). The thickness of the positive electrode foil refers to the thickness of one piece of foil in the part where the positive electrode active material is not covered and there is no insulating layer. The thickness of the negative electrode foil refers to the thickness of one piece of foil in the part where the negative electrode active material is not covered.

[0127] [Comparative Examples 11-12]

[0128] The same procedures as in Examples 11 to 14 were performed except that the value of N1 was set to 3, L was set to L<1.1×F in Comparative Example 11, and D was set to D<1.5 (mm) in Comparative Example 12.

[0129] [evaluate]

[0130] The above-mentioned battery was evaluated. The internal resistance (DC resistance) of the battery was measured, and those below 10.5 (mΩ) were judged as OK, and those other than that were judged as NG. The results are shown below.

[0131] [Table 2]

[0132]

[0133] According to the results of Examples 11 to 14, when L ≥ 1.1 × F and D ≥ 1.5 (mm), the resistance value is 10.5 (mΩ) or less, which is the criterion (judgment OK), whereas according to the results of Comparative Examples 11 and 12, when L < 1.1 × F or D < 1.5 (mm), the resistance value is higher than 10.5 (mΩ) which is the criterion (judgment NG). Therefore, it can be seen from the results of Table 2 that when L ≥ 1.1 × F and D ≥ 1.5 (mm), the internal resistance can be reduced.

[0134] [Examples 21 to 25]

[0135] The thickness of the positive electrode collector plate and the thickness of the positive electrode foil were changed to obtain the difference in internal resistance. When the thickness of the positive electrode collector plate was TC1 and the thickness of the positive electrode foil was TC, the ratio (TC1 / TC) was set to 5 or more and 40 or less, and when the thickness of the negative electrode collector plate was TA1 and the thickness of the negative electrode foil was TA, the ratio (TA1 / TA) was set to 20. The number of grooves passing through the central axis (N1) and the number of grooves not passing through the central axis (N2) were set to 4, L was set to 3.5 (mm), D was set to 4.6 (mm), and F was set to 3.08 (mm).

[0136] [Examples 26 to 30]

[0137] The thickness of the negative electrode collector plate and the thickness of the negative electrode foil were changed to determine the difference in internal resistance. The ratio (TA1 / TA) was set to 5 or more and 40 or less, and the ratio (TC1 / TC) was set to 20. N1, N2, L, D, and F were the same as Examples 21 to 25.

[0138] [Comparative Examples 21 to 24]

[0139] The thickness of the positive electrode collector plate and the thickness of the positive electrode foil are changed, or the thickness of the negative electrode collector plate and the thickness of the negative electrode foil are changed, and the difference in internal resistance is obtained. The ratio (TC1 / TC) or the ratio (TA1 / TA) is set to a value less than 5 or a value greater than 40. N1, N2, L, D, and F are the same as Examples 21 to 25.

[0140] [evaluate]

[0141] The above-mentioned battery was evaluated. The internal resistance (DC resistance) of the battery was measured, and those below 10.5 (mΩ) were judged as OK, and those other than that were judged as NG. The results are shown below. After laser welding, the number of holes in the foil or collector plate was visually observed as the number of holes welded poorly.

[0142] [Table 3]

[0143]

[0144] In Examples 21 to 30, the internal resistance was 10.5 (mΩ) or less as the reference value for determination (determination OK), and in Comparative Examples 21 to 24, it was a value greater than 10.5 (mΩ) (determination NG). In Comparative Examples 21 to 24, holes were opened in the foil or the collector plate due to the heat of welding during welding, resulting in poorly welded portions, and thus the internal resistance was high. Therefore, it can be seen from the results of Table 3 that when the ratio (TC1 / TC) is 5 or more and 40 or less, or when the ratio (TA1 / TA) is 5 or more and 40 or less, the internal resistance can be reduced.

[0145] <2. Modifications>

[0146] An embodiment of the present invention has been specifically described above, but the content of the present invention is not limited to the above-described embodiment, and various modifications can be made based on the technical concept of the present invention.

[0147] The grooves include grooves 43 passing through the central axis and grooves 44 not passing through the central axis, but any grooves may be grooves in other forms. The grooves 43 and 44 are radiating from the central axis, but may be grooves in other directions.

[0148] The positive electrode current collecting plate 24 and the negative electrode current collecting plate 25 include the fan-shaped fan-shaped portions 31 and 33 , but may have other shapes.

[0149] <3. Application examples>

[0150] [Battery pack example]

[0151] Fig.13 1 is a block diagram showing a circuit configuration example when a battery according to an embodiment of the present invention (hereinafter referred to as a secondary battery as appropriate) is applied to a battery pack 330. The battery pack 300 includes a battery pack 301, an exterior, 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.

[0152] In addition, the battery pack 300 has a positive terminal 321 and a negative terminal 322. When charging, the positive terminal 321 and the negative terminal 322 are connected to the positive terminal and the negative terminal of the charger, respectively, for charging. In addition, when the electronic device is used, 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.

[0153] The battery pack 301 is formed by connecting a plurality of secondary batteries 301a in series and / or in parallel. The secondary battery 301a is a secondary battery of the present invention. Fig.13 , an example in which six secondary batteries 301a are connected in a 2-in-parallel and 3-in-series (2P3S) manner is shown, but any connection method of n-in-parallel and m-in-series (n and m are integers) may be used.

[0154] The switch section 304 includes a charge control switch 302a and a diode 302b, and a discharge control switch 303a and a diode 303b, and is controlled by the control section 310. The diode 302b has a polarity of reverse direction relative to the charge current flowing from the positive terminal 321 to the battery pack 301, and a polarity of forward direction relative to the discharge current flowing from the negative terminal 322 to the battery pack 301. The diode 303b has a polarity of forward direction relative to the charge current and a polarity of reverse direction relative to the discharge current. It should be noted that, in the example, the switch section 304 is provided on the + side, but it may also be provided on the - side.

[0155] The charge control switch 302a is turned off when the battery voltage reaches the overcharge detection voltage, and is controlled by the charge and discharge control unit so that the charging current does not flow through the current path of the battery pack 301. After the charge control switch 302a is turned off, discharge can only be performed through the diode 302b. In addition, when a large current flows during charging, the charge control switch 302a is turned off and controlled by the control unit 310 to cut off the charging current flowing through the current path of the battery pack 301.

[0156] The discharge control switch 303a is turned off when the battery voltage reaches the over-discharge detection voltage, and is controlled by the control unit 310 so that the discharge current does not flow through the current path of the battery pack 301. After the discharge control switch 303a is turned off, charging can only be performed through the diode 303b. In addition, when a large current flows during discharge, the discharge control switch 303a is turned off and is controlled by the control unit 310 to cut off the discharge current flowing through the current path of the battery pack 301.

[0157] The temperature detection element 308 is, for example, a thermistor, and is provided near the battery pack 301 to measure the temperature of the battery pack 301 and provide the measured temperature to the control unit 310. The voltage detection unit 311 measures the voltage of the battery pack 301 and each secondary battery 301a constituting the battery pack 301, performs A / D conversion on the measured voltage, and provides the measured voltage to the control unit 310. The current measurement unit 313 measures the current using the current detection resistor 307, and provides the measured current to the control unit 310.

[0158] The switch control unit 314 controls the charge control switch 302a and the discharge control switch 303a of the switch unit 304 based on the voltage and current input from the voltage detection unit 311 and the current measurement unit 313. When the voltage of any one of the secondary batteries 301a becomes less than the overcharge detection voltage or the overdischarge detection voltage, or when a large current flows suddenly, the switch control unit 314 sends a control signal to the switch unit 304, thereby preventing overcharge, overdischarge, and overcurrent charge and discharge.

[0159] Here, for example, 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.

[0160] The charge and discharge switch can use a semiconductor switch such as MOSFET, for example. In this case, the parasitic diode of the MOSFET functions as the diodes 302b and 303b. When a P-channel FET is used as the charge and discharge switch, the switch control unit 314 supplies control signals DO and CO to the gates of the charge control switch 302a and the discharge control switch 303a, respectively. When the charge control switch 302a and the discharge control switch 303a are P-channel, they are turned on by a gate potential that is lower than the source potential by a predetermined value or more. That is, in normal charge and discharge operations, the control signals CO and DO are set to a low level, and the charge control switch 302a and the discharge control switch 303a are set to an on state.

[0161] In addition, for example, during overcharging or overdischarging, the control signals CO and DO are set to a high level, and the charge control switch 302a and the discharge control switch 303a are set to an OFF state.

[0162] The memory 317 is composed of a RAM or a ROM, for example, an EPROM (Erasable Programmable Read Only Memory) as a non-volatile memory. The memory 317 stores in advance the numerical values ​​calculated by the control unit 310, and the internal resistance value of each secondary battery 301a in the initial state measured in the manufacturing process, and the like, which can be appropriately rewritten. In addition, by storing the full charge capacity of the secondary battery 301a, for example, the remaining capacity can be calculated together with the control unit 310.

[0163] The temperature detection unit 318 measures the temperature using the temperature detection element 308, and performs charge and discharge control or correction in the calculation of the remaining capacity when abnormal heat is generated.

[0164] [Examples of power storage systems, etc.]

[0165] The battery according to one embodiment of the present invention described above can be mounted on, for example, electronic equipment, electric vehicles, electric aircraft, power storage devices, or other equipment, or used to supply electric power.

[0166] Examples of electronic devices include notebook personal computers, smart phones, tablet terminals, PDAs (portable information terminals), mobile phones, wearable terminals, cordless telephone handsets, camcorders, digital cameras, electronic books, electronic dictionaries, music players, radios, headphones, game consoles, navigation systems, memory cards, pacemakers, hearing aids, power tools, electric shavers, refrigerators, air conditioners, televisions, stereos, water heaters, microwave ovens, dishwashers, washing machines, dryers, lighting equipment, toys, medical equipment, robots, load regulators, signal machines, and the like.

[0167] In addition, electric vehicles include railway vehicles, golf carts, electric carts, electric vehicles (including hybrid vehicles), etc., which are used as driving power sources or auxiliary power sources. As power storage devices, power storage power sources for buildings such as houses or power generation equipment can be listed.

[0168] Hereinafter, a specific example of a power storage system using a power storage device to which the battery of the present invention is applied will be described in the above-mentioned application example.

[0169] [An example of a power tool]

[0170] Reference Fig.14, an example of an electric tool, such as an electric screwdriver, to which the present invention can be applied is briefly described. The electric screwdriver 431 has a motor 433 such as a DC motor housed in the main body. The rotation of the motor 433 is transmitted to a shaft 434, and the screw is screwed into the object through the shaft 434. The electric screwdriver 431 is provided with a trigger switch 432 operated by the user.

[0171] A battery pack 430 and a motor control unit 435 are housed in a lower frame of the handle of the electric screwdriver 431. As the battery pack 430, the battery pack 300 can be used. The motor control unit 435 controls the motor 433. Each part of the electric screwdriver 431 other than the motor 433 can also be controlled by the motor control unit 435. Although not shown in the figure, the battery pack 430 and the electric screwdriver 431 are engaged by respectively provided engaging parts. As described later, the battery pack 430 and the motor control unit 435 each have a microcomputer. Battery power is supplied from the battery pack 430 to the motor control unit 435, and information about the battery pack 430 is communicated between the microcomputers of both.

[0172] The battery pack 430 can be freely loaded and unloaded relative to the electric screwdriver 431, for example. The battery pack 430 can also be built into the electric screwdriver 431. The battery pack 430 is installed in the charging device when charging. It should be noted that when the battery pack 430 is installed in the electric screwdriver 431, a part of the battery pack 430 is exposed to the outside of the electric screwdriver 431, and the user can see the exposed part. For example, an LED can also be provided on the exposed part of the battery pack 430 so that the user can confirm whether the LED is lit or not.

[0173] The motor control unit 435 controls, for example, the rotation / stop and the rotation direction of the motor 433. In addition, the power supply to the load is cut off when over-discharge occurs. The trigger switch 432 is inserted between the motor 433 and the motor control unit 435, for example. When the user presses the trigger switch 432, the motor 433 is powered and rotates. When the user returns the trigger switch 432, the rotation of the motor 433 stops.

[0174] [Unmanned Aerial Vehicle]

[0175] Reference Fig.15 An example in which the present invention is applied to a power source for an electric aircraft will be described. The present invention can be applied to a power source for an unmanned aircraft (so-called drone). Fig.15 : is a top view of the unmanned aerial vehicle. The fuselage is composed of a cylindrical or square-cylindrical fuselage portion as a central portion and support shafts 442a to 442f fixed to the upper portion of the fuselage portion. As an example, the fuselage portion is formed into a hexagonal cylinder, and six support shafts 442a to 442f extend radially from the center of the fuselage portion at equal angles. The fuselage portion and the support shafts 442a to 442f are made of lightweight and high-strength materials.

[0176] Motors 443a to 443f serving as driving sources for rotating blades are mounted on the front ends of the support shafts 442a to 442f, respectively. Rotating blades 444a to 444f are mounted on the rotating shafts of the motors 443a to 443f. A circuit unit 445 including a motor control circuit for controlling each motor is mounted on the center portion (the upper portion of the machine body) where the support shafts 442a to 442f intersect.

[0177] In addition, a battery unit as a power source is arranged at a position on the lower side of the body. The battery unit has three battery packs to supply power to the motor and the rotating blade pair with an opposing interval of 180 degrees. Each battery pack has, for example, a lithium-ion secondary battery and a battery control circuit that controls charging and discharging. As the battery pack, battery pack 300 can be used. Motor 443a and rotating blade 444a and motor 443d and rotating blade 444d form a pair. Similarly, (motor 443b, rotating blade 444b) and (motor 443e, rotating blade 444e) form a pair, and (motor 443c, rotating blade 444c) and (motor 443f, rotating blade 444f) form a pair. The number of these pairs is equal to the number of battery packs.

[0178] [Electricity storage system for vehicles]

[0179] Reference Fig.16 An example in which the present invention is applied to a power storage system for an electric vehicle will be described. Fig.16 An example of the structure of a hybrid vehicle using a series hybrid system to which the present invention is applied is schematically shown. A series hybrid system is a vehicle that runs using electric power generated by a generator driven by an engine or electric power temporarily stored in a battery, using an electric power driving force conversion device.

[0180] The hybrid vehicle 600 is equipped with an engine 601, a generator 602, an electric power conversion device 603, drive wheels 604a and 604b, wheels 605a and 605b, a battery 608, a vehicle control device 609, various sensors 610, and a charging port 611. The battery pack 300 of the present invention is applied to the battery 608.

[0181] The hybrid vehicle 600 travels using an electric driving force conversion device 603 as a power source. An example of the electric driving force conversion device 603 is a motor. The electric driving force conversion device 603 operates with the power of a battery 608, and the rotational force of the electric driving force conversion device 603 is transmitted to drive wheels 604a and 604b. It should be noted that the electric driving force conversion device 603 can be applied to an AC motor or a DC motor by using direct current-alternating current (DC-AC) or reverse conversion (AC-DC conversion) at necessary positions. Various sensors 610 control the engine speed via a vehicle control device 609 and control the opening of a throttle valve (throttle opening) not shown in the figure. Various sensors 610 include a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

[0182] The rotational force of the engine 601 is transmitted to the generator 602 , and the electric power generated by the generator 602 can be stored in the battery 608 by the rotational force.

[0183] When the hybrid vehicle 600 is decelerated by a brake mechanism (not shown), the resistance during deceleration is applied to the electric driving force conversion device 603 as a rotational force, and the regenerative electric power generated by the electric driving force conversion device 603 by the rotational force is stored in the battery 608 .

[0184] Battery 608 is connected to a power source outside hybrid vehicle 600 , and can receive power supply from the external power source using charging port 611 as an input port, and store the received power.

[0185] Although not shown, an information processing device that performs information processing related to vehicle control based on information related to the secondary battery may be provided. Examples of such an information processing device include an information processing device that displays the remaining battery level based on information related to the remaining battery level.

[0186] It should be noted that the above description is based on a series hybrid vehicle that uses the power generated by the generator driven by the engine or the power temporarily stored in the battery and is driven by a motor. However, the present invention can also be effectively applied to a parallel hybrid vehicle that uses the output of both the engine and the motor as a driving source and appropriately switches between three modes of driving only by the engine, driving only by the motor, and driving by the engine and the motor. In addition, the present invention can also be effectively applied to so-called electric vehicles that are driven only by the drive motor without using an engine.

[0187] Explanation of symbols

[0188] 1…lithium-ion battery, 12…insulating plate, 21…positive electrode, 21A…positive electrode foil, 21B…positive electrode active material layer, 21C…active material non-covered portion of the positive electrode, 22…negative electrode, 22A…negative electrode foil, 22B…negative electrode active material layer, 22C…active material non-covered portion of the negative electrode, 23…separator, 24…positive electrode current collector plate, 25…negative electrode current collector plate, 26…through hole, 27, 28…outer edge portion, 41, 42…end portion, 43…groove passing through the central axis, 44…groove not passing through the central axis, 101…insulating layer.

Claims

1. A secondary battery, The electrode winding body, the positive electrode collector plate, and the negative electrode collector plate are housed in an outer can. The electrode winding body has a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound with a separator interposed therebetween. In this secondary battery, The positive electrode has a covered portion covered with a positive electrode active material layer and a positive electrode active material non-covered portion on a strip-shaped positive electrode foil. The negative electrode has a covered portion covered with a negative electrode active material layer and a negative electrode active material non-covered portion on a strip-shaped negative electrode foil. The positive electrode active material non-covered portion is joined to the positive electrode current collector plate at one end of the electrode winding body. The negative electrode active material non-covered portion is joined to the negative electrode current collector plate at the other end of the electrode winding body. One or both of the positive electrode active material non-covered portion and the negative electrode active material non-covered portion have flat surfaces formed by bending toward the central axis of the wound structure and overlapping with each other, The flat surface has a groove passing through the central axis and a groove not passing through the central axis, and a portion of the flat surface without the grooves, that is, a portion without the groove passing through the central axis and the groove not passing through the central axis, is joined to the positive electrode collector plate or the negative electrode collector plate. The width of the positive electrode active material non-covered portion is greater than the width of the negative electrode active material non-covered portion, and the ends of the positive electrode active material non-covered portion and the ends of the negative electrode active material non-covered portion protrude further outward than the separator. The length of a portion of the positive electrode active material non-covered portion protruding from one end in the width direction of the separator is greater than the length of a portion of the negative electrode active material non-covered portion protruding from the other end in the width direction of the separator.

2. The secondary battery according to claim 1, wherein When the number of grooves passing through the central axis is N1, 3≤N1≤6, and when the number of grooves not passing through the central axis is N2, N1≤N2≤2×N1.

3. The secondary battery according to claim 1 or 2, wherein: When the intersection of the groove passing through the center axis and the outer edge of the flat surface is set as U, the intersection of other grooves passing through the center axis and the outer edge is set as U', the distance from the intersection V of the line segment UU' and the groove that does not pass through the center axis to the outer edge along the groove that does not pass through the center axis is set as F, the length of the groove that does not pass through the center axis is set as L, and the distance from the front end of the inner circumference of the groove that does not pass through the center axis to the peripheral edge of the nearest through hole is set as D, L≥1.1×F and D≥1.5mm.

4. The secondary battery according to claim 1 or 2, wherein: When the thickness of the positive electrode current collector plate is denoted as TC1 and the thickness of the positive electrode foil is denoted as TC, the ratio of the thicknesses of the positive electrode collector plate and the positive electrode foil is denoted as TC, and the ratio of the thicknesses of the positive electrode collector plate and the positive electrode foil is denoted as TC1 and TC, respectively.

5. The secondary battery according to claim 1 or 2, wherein: When the thickness of the negative electrode current collector plate is denoted as TA1 and the thickness of the negative electrode foil is denoted as TA, a ratio of the thicknesses of the negative electrode collector plate and the negative electrode foil is denoted as TA, and the ratio of the thicknesses of the negative electrode collector plate and the negative electrode foil is denoted as TA.

6. The secondary battery according to claim 1 or 2, wherein: The positive electrode collector plate is made of aluminum or aluminum alloy.

7. The secondary battery according to claim 1 or 2, wherein: The negative electrode collector plate is made of nickel, nickel alloy, copper or copper alloy monomer or a composite material thereof.

8. The secondary battery according to claim 1 or 2, wherein: The portion of the positive electrode active material non-covered portion that faces the negative electrode with the separator interposed therebetween includes an insulating layer.

9. The secondary battery according to claim 1 or 2, wherein: The open end of the outer can is sealed by a sealing plate also serving as an external terminal.

10. The secondary battery according to claim 1 or 2, wherein: A portion of the flat surface where no groove passing through the central axis and no groove passing through the central axis exist is joined to the positive electrode current collector plate or the negative electrode current collector plate by welding.

11. A battery pack comprising: The secondary battery according to claim 1; a control unit that controls the secondary battery; and The outer casing houses the secondary battery.

12. An electronic device, A secondary battery according to any one of claims 1 to 10 or a battery pack according to claim 11.

13. An electric tool, A battery pack according to claim 11 is provided, and the battery pack is used as a power source.

14. An electric aircraft comprising: The battery pack according to claim 11; a plurality of rotating blades; a motor to rotate the rotating blades respectively; A supporting shaft, supporting the rotating blades and the motor respectively; a motor control unit, controlling the rotation of the motor; as well as a power supply line for supplying power to the motor, The battery pack is connected to the power supply line.

15. The electric aircraft according to claim 14, wherein: having a plurality of pairs of opposing rotating blades, There are a plurality of battery packs, The number of the multiple pairs of rotating blades is equal to the number of the multiple battery packs.

16. An electric vehicle, A secondary battery according to any one of claims 1 to 10, comprising: a conversion device that receives power supplied from the secondary battery and converts the power into a driving force for the vehicle; and The control device performs information processing related to vehicle control based on the information related to the secondary battery.

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