Secondary battery, electronic device, and power tool

Abstract

[PROBLEM] To provide a battery that does not cause internal short circuit even if repeatedly charged and discharged. [SOLUTION] A secondary battery, an electrode winding body of which is housed in a battery can, has a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are layered with a separator and wound, the positive electrode has positive electrode active material layers on both surfaces of a strip-shaped positive electrode foil, the negative electrode has negative electrode active material layers on both surfaces of a strip-shaped negative electrode foil, the electrode winding body has a positive electrode tab at a central portion of the positive electrode, a negative electrode tab at a winding termination side of the negative electrode, and a flat-plate-shaped foil tab at a winding start side of either or both of the positive electrode and the negative electrode, the foil tab has a plate-shaped portion and a comb-shaped portion, the plate-shaped portion is joined at the winding start side of the positive electrode or the negative electrode, the comb-shaped portion protrudes from the positive electrode or the negative electrode, and the comb-shaped portion is formed as a connection portion of the electrode winding body.

Description

Technical Field

[0001] This invention relates to secondary batteries, electronic devices, and power tools. Background Technology

[0002] Lithium-ion batteries are widely used in machinery, tools, and other applications, making structures that can withstand repeated charging and discharging essential. Repeated charging and discharging can cause deformation and buckling of the inner circumference of the electrode windings within the battery canister, sometimes leading to internal short circuits.

[0003] Patent document 1 discloses that after placing a reinforcing plate on the starting side of the positive electrode winding, it is wound together with the negative electrode and the separator, thereby increasing the strength of the inner periphery of the electrode winding body.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-025912 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] However, in Patent Document 1, when the positive electrode contact is welded to the reinforcing plate, the thickness of the positive electrode contact creates a large drop in the inner circumference of the electrode winding, which can easily lead to internal short circuits. If the thickness of the positive electrode contact is reduced to decrease the drop in the inner circumference, there is also the problem of heat generation when discharging a large current.

[0009] Therefore, one of the objectives of this invention is to provide a battery that will not bend or short-circuit even with repeated charging and discharging.

[0010] Technical solutions for solving technical problems

[0011] To address the aforementioned technical problems, the present invention provides a secondary battery in which the electrode winding body is housed within a battery canister. The electrode winding body has a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound together with a separator in between.

[0012] The positive electrode has positive electrode active material layers on both sides of the strip-shaped positive electrode foil.

[0013] The negative electrode has negative electrode active material layers on both sides of the strip-shaped negative electrode foil.

[0014] The electrode winding body has a positive electrode contact in the central portion of the positive electrode, a negative electrode contact on the winding termination side of the negative electrode, and a flat foil contact on the winding start side of either the positive or negative electrode.

[0015] The foil has a plate-like portion and a comb-like portion. The plate-like portion is joined to the winding start side of the positive or negative electrode, and the comb-like portion protrudes from the positive or negative electrode.

[0016] The comb-tooth section forms the connecting part of the electrode winding body.

[0017] Invention Effects

[0018] According to at least one embodiment of the present invention, a low-resistance battery can be provided that has no drop in the inner circumference of the electrode winding and will not cause an internal short circuit even with repeated charging and discharging. It should be noted that the content of the present invention is not limited to the effects exemplified in this specification. Attached Figure Description

[0019] Figure 1 This is a schematic cross-sectional view of a battery according to one embodiment.

[0020] Figure 2 A to Figure 2 D is a diagram used to illustrate an example of a foil splice.

[0021] Figure 3 A to Figure 3 C is a diagram used to illustrate Example 1.

[0022] Figure 4 A to Figure 4 Figure C is used to illustrate Example 2.

[0023] Figure 5 A to Figure 5 Figure C is used to illustrate Example 3.

[0024] Figure 6 A to Figure 6 Figure C is used to illustrate Example 4.

[0025] Figure 7 A to Figure 7 Figure C is used to illustrate Example 5.

[0026] Figure 8 A to Figure 8 Figure C is used to illustrate Example 6.

[0027] Figure 9 A to Figure 9 Figure C is used to illustrate Example 7.

[0028] Figure 10 A to Figure 10 Figure C is used to illustrate Example 8.

[0029] Figure 11 A to Figure 11 Figure C is used to illustrate Example 9.

[0030] Figure 12 A to Figure 12 Figure C is used to illustrate Example 10.

[0031] Figure 13 A to Figure 13 Figure C is used to illustrate Example 11.

[0032] Figure 14 A to Figure 14 Figure C is used to illustrate Example 12.

[0033] Figure 15 A to Figure 15 C is a diagram used to illustrate Comparative Example 1.

[0034] Figure 16 This is a connection diagram used in the description of a battery pack as an application example of the present invention.

[0035] Figure 17 This is a connection diagram used in the description of a power tool that serves as an application example of the present invention.

[0036] Figure 18 This is a connection diagram used in the description of an electric vehicle, which is an application example of the present invention. Detailed Implementation

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the descriptions will proceed in the following order.

[0038] <1. Implementation Method>

[0039] <2. Variations>

[0040] <3. Application Examples>

[0041] The embodiments described below are preferred examples of the present invention, and the content of the present invention is not limited to these embodiments.

[0042] In this embodiment of the invention, a cylindrical lithium-ion battery is used as an example of a secondary battery. Of course, other batteries besides lithium-ion batteries and batteries other than cylindrical shapes can also be used.

[0043] <1. Implementation Method>

[0044] First, let's explain the overall structure of a lithium-ion battery. Figure 1 This is a schematic cross-sectional view of lithium-ion battery 1. For example, as shown... Figure 1 As shown, the lithium-ion battery 1 is a cylindrical lithium-ion battery 1 in which an electrode winding body 20 is housed inside the battery can 11.

[0045] Specifically, the lithium-ion battery 1 has a pair of insulating plates 12 and 13 and an electrode winding body 20 inside the cylindrical battery can 11. The lithium-ion battery 1 may also have any one or more of the following inside the battery can 11: a thermistor (Positive Temperature Coefficient Thermistor or PTC) and reinforcing components.

[0046] [Battery can]

[0047] The battery can 11 is primarily a component for housing the electrode winding 20. The battery can 11 is a cylindrical container with one open end and the other closed. That is, the battery can 11 has an open end (open end 11N). The battery can 11 contains any one or more of the following metallic materials: iron, aluminum, and their alloys. However, the surface of the battery can 11 may also be plated with any one or more of the following metallic materials: nickel.

[0048] [Insulating board]

[0049] Insulating plates 12 and 13 have a winding axis direction relative to the electrode winding body 20. Figure 1 A sheet-like component with a surface approximately perpendicular to the vertical direction. Insulating plates 12 and 13 are configured to sandwich the electrode winding 20 between them. The insulating plates 12 and 13 are made of materials such as polyethylene terephthalate (PET), polypropylene (PP), and bakelite. Bakelite includes paper bakelite and cloth bakelite, which are made by coating paper or cloth with phenolic resin and then heating it.

[0050] [Riveting Structure]

[0051] At the open end 11N of the battery can 11, the battery cover 14 and the safety valve mechanism 30 are riveted together with a bend 11P through a gasket 15, forming a riveting structure 11R (curled structure). Thus, the battery can 11 is sealed while the electrode winding body 20 and the like are housed inside.

[0052] [Battery cover]

[0053] The battery cover 14 is a component that closes the open end 11N of the battery can 11 when the electrode winding body 20 and the like are housed inside the battery can 11. The battery cover 14 is made of the same material as the battery can 11. The central region of the battery cover 14... Figure 1 The vertical direction protrudes. On the other hand, the area outside the central region of the battery cover 14 (the peripheral region) contacts the safety valve mechanism 30 through the PTC element 16.

[0054] [washer]

[0055] The gasket 15 is a component that seals the gap between the bent portion 11P (also called the curled portion) of the battery can 11 and the battery cover 14 through a space between the bent portion 11P and the battery cover 14. For example, asphalt or similar materials may be applied to the surface of the gasket 15.

[0056] The gasket 15 contains insulating material. The type of insulating material is not particularly limited, and can be a polymer such as polybutylene terephthalate (PBT) or polypropylene (PP). This is because it electrically separates the battery canister 11 and the battery cover 14 while simultaneously sealing the gap between the bent portion 11P and the battery cover 14.

[0057] [Safety Valve Mechanism]

[0058] The safety valve mechanism 30 is mainly used to release the internal pressure of the battery can 11 when the internal pressure rises, thereby releasing the internal pressure. The increase in internal pressure of the battery can 11 is caused by gases and other substances generated during the decomposition reaction of the electrolyte during charging and discharging.

[0059] [Electrode winding]

[0060] In a cylindrical lithium-ion battery, a strip-shaped positive electrode 21 and a strip-shaped negative electrode 22 are wound into a vortex shape, sandwiching a separator 23, and housed in a battery can 11 while immersed in electrolyte. Although not shown, the positive electrode 21 and negative electrode 22 each have a positive electrode active material layer and a negative electrode active material layer formed on one or both sides of the positive electrode foil and negative electrode foil, respectively. The positive electrode foil is made of a metal foil containing aluminum or an aluminum alloy. The negative electrode foil is made of a metal foil containing nickel, a nickel alloy, copper, or a copper alloy. The separator 23 is a porous and insulating membrane that electrically insulates the positive electrode 21 and negative electrode 22 while allowing lithium ions to move.

[0061] A central space (20C) is provided at the center of the electrode winding body 20, which is the space created when the positive electrode 21, negative electrode 22, and diaphragm 23 are wound. A central pin 24 is inserted into the central space 20C. Figure 1 However, center pin 24 can be omitted.

[0062] A positive lead 25 is connected to the positive terminal 21, and a negative lead 26 is connected to the negative terminal 22. Figure 1 The positive lead 25 contains a conductive material such as aluminum. The positive lead 25 is connected to the safety valve mechanism 30 and is electrically connected to the battery cover 14 via a PTC element. The negative lead 26 contains a conductive material such as nickel. The negative lead 26 is electrically connected to the battery canister 11.

[0063] The detailed composition and materials of the positive electrode 21, negative electrode 22, separator 23, and electrolyte will be described later.

[0064] [positive electrode]

[0065] The positive electrode active material layer includes at least a positive electrode material (positive electrode active material) capable of lithium insertion and extraction, and may also include a positive electrode binder and a positive electrode conductive agent. The positive electrode material is preferably a lithium-containing compound (e.g., a lithium-containing composite oxide and a lithium phosphate compound).

[0066] Lithium-containing composite oxides, for example, have layered rock salt or spinel-type crystalline structures. Lithium-containing phosphate compounds, for example, have olivine-type crystalline structures.

[0067] The positive electrode binder contains synthetic rubber or polymeric compounds. Synthetic rubbers include styrene-butadiene rubbers, fluorinated rubbers, and ethylene propylene diene monomer (EPDM) rubbers, etc. Polymeric compounds include polyvinylidene fluoride (PVdF) and polyimide, etc.

[0068] The positive electrode conductive agent is a carbon material such as graphite, carbon black, acetylene black, or Ketjen black. However, the positive electrode conductive agent can also be a metallic material or a conductive polymer.

[0069] [negative electrode]

[0070] The surface of the negative electrode foil is preferably roughened. This is because, through the so-called anchoring effect, the adhesion of the negative electrode active material layer to the negative electrode foil is improved. Roughening methods include, for example, using electrolysis to form microparticles that create irregularities on the surface of the negative electrode foil. Copper foil produced by electrolysis is generally called electrolytic copper foil.

[0071] The negative electrode active material layer includes at least a negative electrode material (negative electrode active material) capable of inserting and de-intercalating lithium, and may also include a negative electrode binder and a negative electrode conductive agent, etc.

[0072] Anode materials may include carbon materials. This is because the crystal structure changes very little during lithium insertion and extraction, thus allowing for a stable high energy density. Furthermore, carbon materials also act as conductive agents in the anode, thereby improving the conductivity of the active material layer.

[0073] Carbon materials can be easily graphitized carbon, difficult-to-graphitize carbon, graphite, low-crystallinity carbon, or amorphous carbon. Carbon materials can take the form of fibers, spheres, granules, or flakes.

[0074] Additionally, the negative electrode material can also include metallic materials. Examples of metallic materials include Li (lithium), Si (silicon), Sn (tin), Al (aluminum), Zr (zinc), and Ti (titanium). Metallic elements form compounds, mixtures, or alloys with other elements; examples include silicon oxide (SiO₂). x (0<x≤2)), silicon carbide (SiC) or an alloy of carbon and silicon, lithium titanate (LTO).

[0075] It is important to note that, for the purpose of achieving high capacity, the anode material preferably contains silicon-containing compounds such as silicon oxide or silicon alloys, or elemental silicon. For example, the silicon oxide content in the anode active material layer is preferably between 5 wt% and 20 wt%. This is because if the content is too low, the high capacity effect will not be achieved, while if it is too high, silicon expansion will impair battery characteristics. It is also important to note that the same applies to the content of silicon alloys and elemental silicon.

[0076] In lithium-ion battery 1, if the open-circuit voltage (i.e., battery voltage) during full charging is above 4.25V, then compared to the case where the open-circuit voltage during full charging is low, even using the same positive electrode active material, the amount of lithium extracted per unit mass will increase. This results in a high energy density.

[0077] [Septum]

[0078] The diaphragm 23 is a porous membrane containing resin, or it can be a laminate of two or more porous membranes. The resin is polypropylene or polyethylene, etc.

[0079] The separator 23 can also use a porous membrane as the substrate layer and contain a resin layer on one or both sides. This is because the separator 23 has improved adhesion to the positive electrode 21 and the negative electrode 22 respectively, thus suppressing the distortion of the electrode winding 20.

[0080] The resin layer contains resins such as PVdF. When forming this resin layer, a solution in which the resin 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 can also be immersed in the solution and then dried. From the perspective of improving heat resistance and battery safety, it is preferable that the resin layer contains inorganic or organic particles. Types of inorganic particles include alumina, aluminum nitride, aluminum hydroxide, magnesium hydroxide, boehmite, talc, silica, mica, etc. Alternatively, a surface layer mainly composed of inorganic particles formed by sputtering, ALD (atomic layer deposition), or similar methods can be used instead of the resin layer.

[0081] Electrolyte

[0082] Electrolytes contain solvents and electrolyte salts, and may also contain additives as needed. Solvents are non-aqueous solvents such as organic solvents, or water. Electrolytes containing non-aqueous solvents are called non-aqueous electrolytes. Non-aqueous solvents include cyclic carbonates, chain carbonates, lactones, chain carboxylic esters, or nitrile (mononitrile), etc.

[0083] Representative examples of electrolyte salts are lithium salts, but other salts may also be included. Lithium salts include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium methanesulfonate (LiCH3SO3), lithium trifluoromethanesulfonate (LiCF3SO3), and dilithium hexafluorosilicate (Li2SF6). These salts can also be used in combination; however, from the perspective of improving battery performance, a combination of LiPF6 and LiBF4 is preferred. The content of the electrolyte salt is not particularly limited, but it is preferably 0.3 mol / kg to 3 mol / kg relative to the solvent.

[0084] [Methods for manufacturing lithium-ion batteries]

[0085] Next, the manufacturing method of the secondary battery will be explained. First, in the case of producing the positive electrode 21, the positive electrode active material, the positive electrode binder, and the positive electrode conductive agent are mixed to prepare a positive electrode mixture. 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 coated on both sides of the 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 compressed and molded using a roller press to obtain the positive electrode 21.

[0086] When making the negative electrode 22, the same process as that used for the positive electrode 21 is also employed.

[0087] Next, the positive electrode lead 25 and the negative electrode lead 26 are connected to the positive electrode foil and the negative electrode foil, respectively, using a welding method. Then, after stacking the positive electrode 21 and the negative electrode 22 in between the separator 23, they are wound up, and fixing tape is attached to the outermost peripheral surface of the separator 23 to form the electrode winding body 20.

[0088] Next, with the insulator in contact with the side of the electrode winding 20 where the negative lead 26 is exposed, the electrode winding 20 is placed inside the battery can 11, and the bottom of the can is connected to the negative lead 26 using a welding method. Next, an insulator is also placed on the side of the electrode winding 20 where the positive lead 25 is exposed, and one end of the positive lead 25 is connected to the safety valve mechanism 30 using a welding method.

[0089] Next, the battery can 11 is machined using a corrugated sheet forming machine (grooving machine) to create a recess in the battery can 11. Then, electrolyte is injected into the battery can 11, immersing the electrode winding 20 in the electrolyte. Finally, the battery cover 14, safety valve mechanism 30, and gasket 15 are installed inside the battery can 11.

[0090] Finally, as Figure 1As shown, the battery cover 14 and the safety valve mechanism 30 are riveted together at the open end 11N of the battery can 11 with a gasket 15 in between, thereby forming a riveting structure 11R.

[0091] Example

[0092] Hereinafter, using the battery 1 manufactured as described above, the present invention will be specifically described based on embodiments concerning the short circuit rate and buckling rate after low-temperature cycling tests and drop tests. It should be noted that the present invention is not limited to the embodiments described below.

[0093] The battery size was set to 18650 (18mm diameter, 65mm height), and the rated capacity was set to 3000mAh. The positive electrode foil 21A was made of Al and had a thickness of 0.015mm. The negative electrode foil 22A was made of Cu and had a thickness of 0.015mm. The separator 23 was made of biaxially stretched polyethylene and had a thickness of 0.010mm. In all embodiments and comparative examples, the negative electrode active material contained carbon and silicon. Specifically, the negative electrode active material contained carbon as the main material, and the silicon oxide content was set to 5wt% in Example 6, 20wt% in Example 8, and 15wt% in other examples.

[0094] The positive electrode contact 52 shown below is equivalent to Figure 1 The positive lead 25 and the negative terminal piece 53 are equivalent to Figure 1 The negative electrode lead 26. In the embodiments and comparative examples, in addition to the tabs 52, 53, etc., foil tabs 31, 32 are also provided on the winding start side of one or both of the positive and negative electrodes. Hereinafter, the foil tab 32 of the negative electrode will be described as an example.

[0095] Hereinafter, the area on the surface of the positive electrode foil 21A covered with a positive electrode active material layer will be referred to as the positive electrode active material covered portion 21B, and the area on the surface of the positive electrode foil 21A not covered with a positive electrode active material layer will be referred to as the positive electrode active material uncovered portion 21C. Similarly, the area on the surface of the negative electrode foil 22A covered with a negative electrode active material layer will be referred to as the negative electrode active material covered portion 22B, and the area on the surface of the negative electrode foil 22A not covered with a negative electrode active material layer will be referred to as the negative electrode active material uncovered portion 22C.

[0096] The positive electrode 21 or the negative electrode 22 has a foil tab 31 for the positive electrode or a foil tab 32 for the negative electrode on the winding start side. For example, as Figure 2 As shown in Figure A, the foil contact 32 of the negative electrode has a flat plate shape and is composed of a plate-shaped portion 36 and a comb-shaped portion 34. The plate-shaped portion 36 of the foil contact 32 has a width of 24 mm, which is larger than the width of existing contact plates, and serves to collect current from the negative electrode 22. The comb-shaped portion 34 is provided at the end of the foil contact 32.

[0097] exist Figure 2 In A, the comb teeth 34 are in the shape of a comb with a width of 3 mm and a length of 5 mm. Figure 2 The spacing of the strip-shaped protrusions in the comb tooth section 34 of component A is 7mm or 8mm from the winding start side, and is not a fixed value. The spacing of the strip-shaped protrusions in the comb tooth section 34 is designed to gradually increase from the winding start side so that the width of the overlapping strip-shaped protrusions (foil splice sections) due to winding delays during winding overlaps within approximately ±1mm, preventing problems during welding to the can bottom and safety valve. The spacing of the strip-shaped protrusions in the foil splice 32 is set to gradually increase from the winding start side so that the strip-shaped protrusions of the comb tooth section 34 form a clustered shape when the foil splice 32 is wound. Figure 2 As shown in Figure B, for example, the plate-shaped portion 36 of the negative electrode foil patch 32 is bonded to the non-covered portion 22C of the active material of the negative electrode, which is the winding start side of the negative electrode 22, at three welding points 61 (the parts marked with shading in the figure). At this time, the foil patch 32 is arranged such that the comb-like portion 34 protrudes from the negative electrode 22. It should be noted that in the case of the positive electrode foil patch 31, the same configuration as the negative electrode foil patch 32 can also be adopted.

[0098] Materials used for the foil tab 31 of the positive electrode include, for example, aluminum, titanium, and stainless steel (SUS). SUS304 dissolves after heating aging in a 4.2V system using LCO or NCA positive electrodes, but does not dissolve in a 3.6V system using LiFePO4 or similar electrodes. SUS316 does not dissolve even after heating aging in a 4.2V system using LCO or NCA positive electrodes. Thus, regarding SUS, the raw material can be appropriately selected according to the battery voltage.

[0099] The foil contact 32 is wound together with the negative electrode 22, as shown. Figure 2 As shown in Figure C, the comb-like portions 34 of the foil splice 32 are staggered and overlapped, and then assembled at one point to form a connecting portion 42 of the foil splice 32. The connecting portion 42 is engaged with the bottom of the battery can 11. Figure 2 A and Figure 2 The comb portion 34 of the foil sheet 32 ​​of B has three strip-shaped protrusions. Figure 2 In section C, the plate-shaped portion 36 of the foil strip 32 is wound twice, and the connecting portion 42 becomes a structure with three overlapping strip-shaped protrusions. The wound foil strip 32 is a reinforcement of the inner circumference of the electrode winding body 20, and can prevent the inner circumference of the electrode winding body 20 from being bent or deformed during the charging and discharging of the battery 1.

[0100] The comb-tooth portion of the negative electrode foil 32 can also be divided into four, six, or more comb-tooth portions 34, for example. Figure 2As in D, when wound, the comb-like portions 34 of the foil sheet 32 ​​converge at two points and overlap, forming two opposing connecting portions 42A and 42B. In this case, the comb-like portions 34 of the negative electrode foil sheet 32 ​​have alternating long and short strip-like protrusions (not shown). When wound, the long strip-like protrusions overlap each other and the short strip-like protrusions overlap each other, thus forming... Figure 2 As with D, the foil tab 32 can form a longer connecting portion 42A and a shorter connecting portion 42B. By changing the lengths of the two connecting portions 42A and 42B, it can be folded and welded to the bottom of the can.

[0101] The foil tab 31 of the positive electrode has the same shape as the foil tab 32 of the negative electrode, but differs in that the comb portion 33 is longer. Similarly, the comb portion 33 protrudes from the positive electrode 21 and is wound together with the positive electrode 21, with multiple strip-shaped protrusions forming one or two connecting portions 41. In the case of two connecting portions 41, the lengths of the two connecting portions 41 are not particularly different. The plate-shaped portion 35 of the foil tab 31 is joined by welding at the non-covered portion 21C of the active material of the positive electrode on the winding start side, which is the positive electrode. The wound foil tab 31 is a reinforcement of the inner periphery of the electrode winding body 20, and can prevent the inner periphery of the electrode winding body 20 from bending or deforming during the charging and discharging of the battery 1.

[0102] Based on the structural limitations of the foil tabs 31 and 32, which require a thickness that serves as a reinforcement for the inner periphery of the electrode winding body 20, and the internal structure of the battery canister 11, the thickness of the foil tabs 31 and 32 is preferably 0.020 mm or more and 0.100 mm or less. More preferably, the thickness of the foil tabs 31 and 32 is 0.030 mm or more and 0.080 mm or less. The material of the negative electrode foil tab 32 is preferably any one of copper, copper-nickel alloy, nickel, zinc, copper-zinc alloy, copper-zinc-nickel alloy, or a composite material thereof. Furthermore, the number of turns of the foil tab 32 is preferably more than one turn and less than four turns.

[0103] The cross-sectional areas of the connecting portions 41, 42, 42A, and 42B of the foil tabs 31 and 32 shown below are represented by the product of the width and thickness of the connecting portions 41, 42, 42A, and 42B of the foil tabs 31 and 32. Similarly, the cross-sectional areas of the tabs 52, 53, and 54 are represented by the product of the width and thickness of the tabs 52, 53, and 54. In all embodiments and Comparative Example 1, the width of the tab 52 located at the center of the positive electrode 21 is set to 6 mm, and the thickness is set to 0.1 mm (cross-sectional area of ​​0.6 mm). 2The material is set to Al. The contact piece 52 located in the center of the positive electrode 21 and the non-covered portion 21C of the active material of the positive electrode to which the contact piece 52 is attached are covered by insulating tape 51. The thickness of the foil contact piece 31 located on the winding start side of the positive electrode 21 is set to 0.05 mm, and the width of the strip-shaped protrusion of the comb portion 33 is set to 3 mm. The material is set to Al. The foil contact piece 31 located on the winding start side of the positive electrode 21 and the non-covered portion 21C of the active material of the positive electrode to which the foil contact piece 31 is attached are covered by insulating tape 51. The thickness of the contact piece 53 located on the winding end side of the negative electrode 22 is set to 0.08 mm, and the width is set to 3 mm (cross-sectional area is 0.24 mm²). 2 Set the material to CuNi.

[0104] Furthermore, in Examples 1 to 10, the thickness of the foil sheet 32 ​​located on the winding start side of the negative electrode 22 is set to 0.04 mm, and the width of the strip-shaped protrusion of the comb tooth portion 34 is set to 3 mm (the cross-sectional area of ​​one strip-shaped protrusion of the comb tooth portion 34 is 0.12 mm²). 2 The material was set to Cu. In Examples 11 to 14 and Comparative Example 1, the thickness of the tab 54 located on the winding start side of the negative electrode 22 was set to 0.08 mm, and the width was set to 3 mm (cross-sectional area of ​​0.24 mm²). 2 Set the material to CuNi.

[0105] The thicknesses of splices 52, 53, and 54, and foil splices 31 and 32 were measured using a micrometer (Mitutoyo MDC-25MX).

[0106] Figure 3 A to Figure 15 A( Figures 3 to 15 Figure A) shows a schematic diagram of the positive electrode 21 before winding on the upper side of each figure, and a schematic diagram of the negative electrode 22 before winding on the lower side of each figure. The right side of each figure is the winding start side, and the left side of each figure is the winding end side. Figure 3 B to Figure 15 B( Figures 3 to 15 Figure B) shows the... Figure 3 A to Figure 15 A schematic diagram of the electrode winding body 20 after the positive electrode 21 and negative electrode 22 of A are wound together with the separator. The upper side of each diagram is the battery cover 14 side, and the lower side of each diagram is the bottom side of the battery can 11. Figure 3 C to Figure 15 C( Figures 3 to 15 C) in each figure represents... Figure 3 B to Figure 15 A schematic diagram of the electrode winding body 20 of B being inserted into the battery canister 11 to form battery 1, omitting details such as the gasket 15.

[0107] [Example 1]

[0108] like Figure 3 As shown in Figure A, a contact 52 is positioned at the center of the positive electrode 21, a foil contact 32 is positioned at the beginning of the winding of the negative electrode 22, and a contact 53 is positioned at the end of the winding of the negative electrode 22. The comb-like portion 34 of the foil contact 32 is composed of six strip-shaped protrusions. Figure 3 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the diaphragm 23 in between, and the six strip-shaped protrusions of the comb tooth portion 34 are wound in such a way that they are assembled into two connecting portions 42A and 42B with every other overlap. The number of turns of the foil sheet 32 ​​of the negative electrode is set to 2.5 turns, and the total cross-sectional area of ​​the connecting portions 42A and 42B of the foil sheet 32 ​​of the negative electrode is set to 0.72 mm². 2 .like Figure 3 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tab 32 joined together, is disposed within the battery canister 11. The content of silicon oxide in the negative electrode active material is set to 15 wt%.

[0109] [Example 2]

[0110] like Figure 4 As shown in Figure A, a tab 52 is positioned at the center of the positive electrode 21, a foil tab 32 is positioned at the beginning of the winding of the negative electrode 22, and a tab 53 is positioned at the end of the winding of the negative electrode 22. The comb-like portion 34 of the foil tab 32 is composed of four strip-shaped protrusions. Figure 4 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the diaphragm 23 in between, and the four strip-shaped protrusions of the comb tooth portion 34 are wound in such a way that they are assembled into two connecting portions 42A and 42B with every other overlap. The number of turns of the foil sheet 32 ​​of the negative electrode is set to 1.5 turns, and the total cross-sectional area of ​​the connecting portions 42A and 42B of the foil sheet 32 ​​of the negative electrode is set to 0.48 mm. 2 .like Figure 4 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tab 32 joined together, is disposed within the battery canister 11. The content of silicon oxide in the negative electrode active material is set to 15 wt%.

[0111] [Example 3]

[0112] like Figure 5 As shown in Figure A, a contact 52 is positioned at the center of the positive electrode 21, a foil contact 32 is positioned at the beginning of the winding of the negative electrode 22, and a contact 53 is positioned at the end of the winding of the negative electrode 22. The comb-like portion 34 of the foil contact 32 is composed of three strip-shaped protrusions. Figure 5As shown in Figure B, the positive electrode 21 and negative electrode 22 are overlapped with the diaphragm 23 in between, and the three strip-shaped protrusions of the comb portion 34 are overlapped into one connecting portion 42. The foil sheet 32 ​​of the negative electrode is wound twice, and the total cross-sectional area of ​​the connecting portion 42 of the foil sheet 32 ​​of the negative electrode is set to 0.36 mm². 2 .like Figure 5 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tab 32 joined together, is disposed within the battery canister 11. The content of silicon oxide in the negative electrode active material is set to 15 wt%.

[0113] [Example 4]

[0114] like Figure 6 As shown in Figure A, a contact 52 is positioned at the center of the positive electrode 21, a foil contact 32 is positioned at the beginning of the winding of the negative electrode 22, and a contact 53 is positioned at the end of the winding of the negative electrode 22. The comb-like portion 34 of the foil contact 32 is composed of two strip-shaped protrusions. Figure 6 As shown in Figure B, the positive electrode 21 and negative electrode 22 are overlapped with the diaphragm 23 in between, and the two strip-shaped protrusions of the comb portion 34 are overlapped to form a connecting portion 42. The number of turns of the foil sheet 32 ​​of the negative electrode is set to one, and the total cross-sectional area of ​​the connecting portion 42 of the foil sheet 32 ​​of the negative electrode is set to 0.24 mm. 2 .like Figure 6 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tab 32 joined together, is disposed within the battery canister 11. The content of silicon oxide in the negative electrode active material is set to 15 wt%.

[0115] [Example 5]

[0116] like Figure 7 As shown in Figure A, a tab 52 is positioned at the center of the positive electrode 21, and a foil tab 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil tab 31 is composed of six strip-shaped protrusions. A foil tab 32 is positioned on the winding start side of the negative electrode 22, and a tab 53 is positioned on the winding end side of the negative electrode 22. The comb portion 34 of the foil tab 32 is composed of six strip-shaped protrusions. Figure 7 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with respect to the diaphragm 23. For each foil patch 31 and foil patch 32, the six strip-shaped protrusions of the comb portions 33 and 34 are wound in such a way that they overlap every other portion to form two connecting portions 41, 41 and two connecting portions 42A, 42B. The number of turns of the foil patch 31 of the positive electrode is set to 2.5 turns, and the total cross-sectional area of ​​the connecting portion 41 of the foil patch 31 of the positive electrode is set to 0.9 mm². 2 The number of turns of the foil splice 32 of the negative electrode is set to 2.5, and the total cross-sectional area of ​​the connecting portions 42A and 42B of the foil splice 32 of the negative electrode is set to 0.72 mm². 2.like Figure 7 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tabs 31 and 32 joined together, is disposed within the battery canister 11. The content of silicon oxide contained in the negative electrode active material is set to 15 wt%.

[0117] [Example 6]

[0118] like Figure 8 As shown in Figure A, a tab 52 is positioned at the center of the positive electrode 21, and a foil tab 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil tab 31 is composed of four strip-shaped protrusions. A foil tab 32 is positioned on the winding start side of the negative electrode 22, and a tab 53 is positioned on the winding end side of the negative electrode 22. The comb portion 34 of the foil tab 32 is composed of four strip-shaped protrusions. Figure 8 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the diaphragm 23 in between. For each foil patch 31 and foil patch 32, the four strip-shaped protrusions of the comb portions 33 and 34 are wound in such a way that they overlap every other one to form two connecting portions 41, 41 and two connecting portions 42A, 42B. The number of turns of the positive electrode foil patch 31 is set to 1.5 turns, and the total cross-sectional area of ​​the connecting portion 41 of the positive electrode foil patch 31 is set to 0.6 mm². 2 The number of turns of the foil splice 32 of the negative electrode is set to 1.5 turns, and the total cross-sectional area of ​​the connecting portions 42A and 42B of the foil splice 32 of the negative electrode is set to 0.48 mm². 2 .like Figure 8 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tabs 31 and 32 joined together, is disposed within the battery canister 11. The content of silicon oxide contained in the negative electrode active material is set to 5 wt%.

[0119] [Example 7]

[0120] Except that the content of silicon oxide in the negative electrode active material is set to 15 wt%, it is the same as in Example 6.

[0121] [Example 8]

[0122] Except that the content of silicon oxide in the negative electrode active material is set to 20 wt%, it is the same as in Example 6.

[0123] [Example 9]

[0124] like Figure 9 As shown in Figure A, a tab 52 is positioned at the center of the positive electrode 21, and a foil tab 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil tab 31 is composed of three strip-shaped protrusions. A foil tab 32 is positioned on the winding start side of the negative electrode 22, and a tab 53 is positioned on the winding end side of the negative electrode 22. The comb portion 34 of the foil tab 32 is composed of three strip-shaped protrusions. Figure 9As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the diaphragm 23 in between. For each foil tab 31 and 32, the three strip-shaped protrusions of the comb portions 33 and 34 are overlapped to form a connecting portion 41 and a connecting portion 42. The foil tab 31 of the positive electrode is wound twice, and the total cross-sectional area of ​​the connecting portion 41 of the foil tab 31 of the positive electrode is set to 0.45 mm². 2 The number of turns of the foil splice 32 of the negative electrode is set to two, and the total cross-sectional area of ​​the connecting portion 42 of the foil splice 32 of the negative electrode is set to 0.36 mm. 2 .like Figure 9 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tabs 31 and 32 joined together, is disposed within the battery canister 11. The content of silicon oxide contained in the negative electrode active material is set to 15 wt%.

[0125] [Example 10]

[0126] like Figure 10 As shown in Figure A, a tab 52 is positioned at the center of the positive electrode 21, and a foil tab 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil tab 31 is composed of two strip-shaped protrusions. A foil tab 32 is positioned on the winding start side of the negative electrode 22, and a tab 53 is positioned on the winding end side of the negative electrode 22. The comb portion 34 of the foil tab 32 is composed of two strip-shaped protrusions. Figure 10 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the diaphragm 23 in between. For each foil patch 31 and foil patch 32, the two strip-shaped protrusions of the comb portions 33 and 34 are overlapped to form a connecting portion 41 and a connecting portion 42, and the number of turns of the positive electrode foil patch 31 is set to one revolution. The total cross-sectional area of ​​the connecting portion 41 of the positive electrode foil patch 31 is set to 0.3 mm². 2 The number of turns of the foil splice 32 of the negative electrode is set to one revolution, and the total cross-sectional area of ​​the connecting portion 42 of the foil splice 32 of the negative electrode is set to 0.24 mm. 2 .like Figure 10 As shown in Figure C, an electrode winding 20, with tabs 52 and 53 and foil tabs 31 and 32 joined together, is disposed within the battery canister 11. The content of silicon oxide contained in the negative electrode active material is set to 15 wt%.

[0127] [Example 11]

[0128] like Figure 11 As shown in Figure A, a contact 52 is positioned at the center of the positive electrode 21, and a foil contact 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil contact 31 is composed of six strip-shaped protrusions. A contact 54 is positioned on the winding start side of the negative electrode 22, and a contact 53 is positioned on the winding end side of the negative electrode 22. Figure 11As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the separator 23 in between. For the foil connector 31, the six strip-shaped protrusions of the comb portion 33 are wound in such a way that they overlap and form two connecting portions 41, 41. The number of turns of the foil connector 31 of the positive electrode 21 is set to 2.5 turns, and the total cross-sectional area of ​​the connecting portions 41 of the foil connector 31 of the positive electrode is set to 0.9 mm². 2 The cross-sectional area of ​​the negative electrode contact 54 is set to 0.24 mm². 2 .like Figure 11 As shown in Figure C, an electrode winding 20, with tabs 52, 53, 54 and foil tab 31 joined together, is disposed inside a battery can. The content of silicon oxide in the negative electrode active material is set to 15 wt%.

[0129] [Example 12]

[0130] like Figure 12 As shown in Figure A, a contact 52 is positioned at the center of the positive electrode 21, and a foil contact 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil contact 31 is composed of four strip-shaped protrusions. A contact 54 is positioned on the winding start side of the negative electrode 22, and a contact 53 is positioned on the winding end side of the negative electrode 22. Figure 12 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with respect to the separator 23. For the foil connector 31, the four strip-shaped protrusions of the comb portion 33 are wound in such a way that they overlap every other time to form two connecting portions 41, 41. The number of turns of the foil connector 31 of the positive electrode is set to 1.5 turns, and the total cross-sectional area of ​​the connecting portions 41 of the foil connector 31 of the positive electrode is set to 0.6 mm². 2 The cross-sectional area of ​​the negative electrode contact 54 is set to 0.24 mm². 2 .like Figure 12 As shown in Figure C, an electrode winding 20, with tabs 52, 53, 54 and foil tab 31 joined together, is disposed within the battery canister 11. The content of silicon oxide contained in the negative electrode active material is set to 15 wt%.

[0131] [Example 13]

[0132] like Figure 13 As shown in Figure A, a contact 52 is positioned at the center of the positive electrode 21, and a foil contact 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil contact 31 is composed of three strip-shaped protrusions. A contact 54 is positioned on the winding start side of the negative electrode 22, and a contact 53 is positioned on the winding end side of the negative electrode 22. Figure 13 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the separator 23 in between, and the foil splice 31 is wound in such a way that the three strip-shaped protrusions of the comb portion 33 overlap to form a connecting portion 41. The number of turns of the foil splice 31 of the positive electrode is set to two, and the total cross-sectional area of ​​the connecting portion 41 of the foil splice 31 of the positive electrode is set to 0.45 mm.2 The cross-sectional area of ​​the negative electrode contact 54 is set to 0.24 mm². 2 .like Figure 13 As shown in Figure C, an electrode winding 20, with tabs 52, 53, 54 and foil tab 31 joined together, is disposed within the battery canister 11. The content of silicon oxide contained in the negative electrode active material is set to 15 wt%.

[0133] [Example 14]

[0134] like Figure 14 As shown in Figure A, a contact 52 is positioned at the center of the positive electrode 21, and a foil contact 31 is positioned on the winding start side of the positive electrode 21. The comb portion 33 of the foil contact 31 is composed of two strip-shaped protrusions. A contact 54 is positioned on the winding start side of the negative electrode 22, and a contact 53 is positioned on the winding end side of the negative electrode 22. Figure 14 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the separator 23 in between, and the foil splice 31 is wound in such a way that the two strip-shaped protrusions of the comb portion 33 overlap to form a connecting portion 41. The number of turns of the foil splice 31 of the positive electrode is set to one, and the total cross-sectional area of ​​the connecting portion 41 of the foil splice 31 of the positive electrode is set to 0.3 mm. 2 The cross-sectional area of ​​the negative electrode contact 54 is set to 0.24 mm². 2 .like Figure 14 As shown in Figure C, an electrode winding 20, with tabs 52, 53, 54 and foil tab 31 joined together, is disposed within the battery canister 11. The content of silicon oxide contained in the negative electrode active material is set to 15 wt%.

[0135] [Comparative Example 1]

[0136] like Figure 15 As shown in Figure A, a contact 52 is positioned at the middle of the positive electrode 21, a contact 54 is positioned at the beginning of the winding of the negative electrode 22, and a contact 53 is positioned at the end of the winding of the negative electrode 22. Figure 15 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped and wound together with the separator 23 in between, and the cross-sectional area of ​​the negative electrode contact 54 is set to 0.24 mm². 2 .like Figure 15 As shown in Figure C, the electrode winding 20, with tabs 52, 53, and 54 attached, is disposed within the battery canister 11. The content of silicon oxide in the negative electrode active material is set to 15 wt%.

[0137] [Evaluate]

[0138] For battery 1 in the above example, the internal resistance of the battery is calculated, the short circuit rate is determined by a drop test after a low-temperature cycling test, and the flexural failure rate is determined by CT imaging. A comprehensive evaluation is then performed based on these results. The battery's internal resistance, low-temperature cycling test, drop test, and CT imaging are described below.

[0139] <Battery internal resistance>

[0140] The internal resistance of the battery is determined based on the AC impedance measurement at a frequency of 1 kHz.

[0141] <Low Temperature Cycling Test>

[0142] Ambient temperature: 0℃

[0143] Charging: CC / CV, 4.25V / 1C, 100mA cut

[0144] Discharge: 2C, 2Vcut (Recharge will begin when the battery temperature reaches 0°C after discharge).

[0145] Cycle count: The number of cycles in which the discharge rate is reduced in stages based on a capacity retention rate of 30%, and finally continues until the capacity retention rate reaches 30% at a low rate (0.5C).

[0146] When the maintenance rate relative to the initial discharge capacity reaches below 30%, the discharge rate is reduced to 1C. When it also reaches below 30%, it is reduced to 0.5C, and the test is continued until it reaches below 30%.

[0147] <Drop Test>

[0148] Some changes have been made to the content specified in the "Lithium Secondary Battery Safety Assessment Benchmark Guide" (SBA G1101). Specifically, the drop test specified in SBA G1101 is a test of dropping 10 times from a height of 1.9m onto concrete, but in the drop test of this assessment, the number of drops is set to 20, and the probability of short circuit occurrence is calculated for n=10.

[0149] <CT scan>

[0150] Following a drop test after low-temperature cycling, the inner circumference of the electrode winding was observed using an X-ray CT scanner. The proportion of cells that caused buckling was considered the buckling incidence rate. The number of tests was set to 10.

[0151]

[0152] In Examples 1 to 14, the short-circuit occurrence rate and buckling occurrence rate were 0%, and the overall evaluation was OK. In contrast, in Comparative Example 1, the short-circuit occurrence rate and buckling occurrence rate were high, and the overall evaluation was NG. It can be seen that if foil tabs 31 and 32 are present on the winding start side of either or both of the positive electrode 21 and the negative electrode 22, the overall evaluation is OK. In Examples 1 to 14, the inner circumference of the electrode winding body was not distorted and remained perfectly round. In contrast, in Comparative Example 1, the inner circumference of the electrode winding body was distorted and did not remain perfectly round. The silicon oxide content that was OK in the overall evaluation was 5 wt% or more and 20 wt% or less. As can be clearly seen from Table 1, when either or both of the positive electrode 21 and the negative electrode 22 have foil tabs 31 and 32 with comb-tooth portions 33 and 34 on the winding start side, and the comb-tooth portions 33 and 34 protrude from the positive electrode 21 or the negative electrode 22, and the strip-shaped protrusions of the comb-tooth portions 33 and 34 overlap and aggregate into one or more, forming the connecting portions 41, 42, 42A, and 42B of the foil tabs 31 and 32, the battery 1 will not bend or have an internal short circuit even if it is repeatedly charged and discharged.

[0153] <2. Variations>

[0154] The above describes one embodiment of the present invention in detail, but the content of the present invention is not limited to the above embodiment, and various modifications can be implemented based on the technical concept of the present invention.

[0155] The dimensions of battery 1 are set to 18650 (18mm in diameter and 65mm in height), but other dimensions are also possible. The rated capacity of battery 1 is set to 3000mAh, but other values ​​are also possible. The thicknesses of the positive electrode foil 21A, the negative electrode foil 22A, and the separator 23 are also not limited to the values ​​mentioned above. The number of strip-shaped protrusions in the comb teeth 33 and 34 is not limited to the embodiment and other values ​​are also possible.

[0156] <3. Application Examples>

[0157] (1) Battery pack

[0158] Figure 16 This is a block diagram illustrating a circuit configuration example when the battery 1 according to an embodiment or example of the present invention is applied to a battery pack 300. The battery pack 300 includes a combined battery 301, a switching unit 304 including a charging control switch 302a and a discharging 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, thereby enabling charging and discharging control when abnormal heat is generated, or calculating and correcting the remaining capacity of the battery pack 300.

[0159] When the battery pack 300 is being charged, the positive terminal 321 and the negative terminal 322 are connected to the positive and negative terminals of the charger, respectively, for charging. Additionally, 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 and negative terminals of the electronic device, respectively, for discharging.

[0160] The combined battery 301 is formed by connecting multiple secondary batteries 301a in series and / or parallel. Figure 16 The example shown is a case where six secondary batteries 301a are connected in a 2-in-parallel and 3-in-series (2P3S) configuration, but any connection method is also possible.

[0161] Temperature detection unit 318 is connected to temperature detection element 308 (e.g., thermistor), measures the temperature of battery pack 301 or battery stack 300, and supplies the measured temperature to control unit 310. Voltage detection unit 311 measures the voltage of battery pack 301 and each secondary battery 301a constituting it, performs A / D conversion on the measured voltage, and supplies it to control unit 310. Current measurement unit 313 measures the current using current detection resistor 307 and supplies the measured current to control unit 310.

[0162] The switch control unit 314 controls the charging control switch 302a and the discharging 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 either of the secondary batteries 301a reaches below the overcharge detection voltage or the over-discharge detection voltage, or when a large current flows rapidly, the switch control unit 314 sends an OFF control signal to the switch unit 304 to prevent overcharging, over-discharging, and overcurrent charging / discharging. Here, when the secondary battery is a lithium-ion secondary battery, the overcharge detection voltage is set, for example, to 4.20V ± 0.05V, and the over-discharge detection voltage is set, for example, to 2.4V ± 0.1V.

[0163] After the charging control switch 302a or the discharging control switch 303a is turned off, charging or discharging can be performed solely via diode 302b or diode 303b. These charging and discharging switches can use semiconductor switches such as MOSFETs. In this case, the parasitic diodes of the MOSFET function as diodes 302b and 303b. It should be noted that... Figure 16 The switch 304 is located on the + side, but it can also be located on the - side.

[0164] The memory 317 is composed of RAM and ROM, including, for example, EPROM (Erasable Programmable Read Only Memory), which is a non-volatile memory. Values ​​calculated by the control unit 310 and battery characteristics of each secondary battery 301a in its initial state measured during the manufacturing process are pre-stored in the memory 317, and it can also be rewritten as needed. Furthermore, by pre-stored the full charge capacity of the secondary battery 301a, the remaining capacity can be calculated in cooperation with the control unit 310.

[0165] (2) Electronic devices

[0166] The battery 1 described in the above embodiments or examples of the present invention can be installed in electronic devices, electric transportation equipment, energy storage devices, and other equipment to supply power.

[0167] Examples of electronic devices include laptops, smartphones, tablets, PDAs (portable information terminals), mobile phones, wearable devices, camcorders, digital still cameras, e-books, music players, headphones, game consoles, pacemakers, hearing aids, power tools, televisions, lighting equipment, toys, medical devices, and robots. Additionally, electric transportation equipment, energy storage devices, power tools, and electric unmanned aerial vehicles, described later, can also be broadly included in the category of electronic devices.

[0168] Examples of electric transportation equipment include electric vehicles (including hybrid vehicles), electric motorcycles, electric-assisted bicycles, electric buses, electric mobility scooters, automated guided vehicles (AGVs), and railway vehicles. Additionally, electric passenger aircraft and electric unmanned aerial vehicles for transportation are also included. The secondary battery involved in this invention is used not only as a power source for their operation but also as an auxiliary power source and a power source for energy regeneration.

[0169] Examples of energy storage devices include commercial or residential energy storage modules, power storage devices for buildings such as residences, buildings, and offices, and power generation equipment.

[0170] (3) Power tools

[0171] Reference Figure 17 A brief description will be given of an electric screwdriver as an example of an electric tool to which the present invention can be applied. The electric screwdriver 431 is equipped with a motor 433 that transmits rotational power to a shaft 434 and a trigger switch 432 for user operation. By operating the trigger switch 432, screws or the like are driven into the object via the shaft 434.

[0172] The battery pack 430 and the motor control unit 435 are housed within the lower housing of the handle of the electric screwdriver 431. The battery pack 430 can be the aforementioned battery pack 300. The battery pack 430 is either built into the electric screwdriver 431 or can be easily installed and removed from the electric screwdriver 431. The battery pack 430 can be installed in a charging device either built into the electric screwdriver 431 or removed from it.

[0173] The battery pack 430 and the motor control unit 435 each have a microcomputer. Power is supplied from the battery pack 430 to the motor control unit 435, and the charging and discharging information of the battery pack 430 is communicated between the two microcomputers. The motor control unit 435 can control the rotation / stop and rotation direction of the motor 433, and can cut off the power supply to the load (motor 433, etc.) in case of over-discharge.

[0174] (4) Energy storage system for electric vehicles

[0175] As an example of applying the present invention to an energy storage system for electric vehicles. Figure 18 The diagram schematically illustrates a configuration example of a hybrid vehicle (HV) employing a series hybrid system. A series hybrid system is a vehicle that uses electricity generated by a generator that powers the engine, or electricity temporarily stored in a battery, to drive via an electric drive conversion device.

[0176] The hybrid vehicle 600 includes an engine 601, a generator 602, an electric drive power conversion device 603 (DC motor or AC motor, hereinafter referred to as "motor 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 or a storage module equipped with multiple batteries 1 of the present invention can be applied to the battery 608. The secondary battery can be cylindrical, square, or laminated.

[0177] The electric motor 603 operates powered by the battery 608, and its rotational force is transmitted to the drive wheels 604a and 604b. The rotational force of the engine 601 is transmitted to the generator 602, which stores the electricity generated by the generator 602 in the battery 608. Various sensors 610 control the engine speed or the opening of a throttle valve (not shown) either via the vehicle control unit 609. These sensors 610 include speed sensors, acceleration sensors, engine speed sensors, etc.

[0178] When the hybrid vehicle 600 is decelerated by a braking mechanism (not shown), the resistance during deceleration is applied as a rotational force to the motor 603, and the regenerative power generated by this rotational force is stored in the battery 608. Additionally, although not shown, an information processing device (e.g., a battery level display device) may be included to perform vehicle control-related information processing based on information related to the secondary battery. The battery 608 can be connected to an external power source via the charging port 611 of the hybrid vehicle 600 to receive and store electricity. Such an HV vehicle is referred to as a plug-in hybrid electric vehicle (PHV or PHEV).

[0179] The above explanation uses a series hybrid vehicle as an example, but the present invention can also be applied to hybrid vehicles that use a parallel connection of the engine and motor, or a combination of series and parallel connections. Furthermore, the present invention can also be applied to electric vehicles (EVs or BEVs) and fuel cell vehicles (FCVs) that do not use an engine but rely solely on a drive motor for propulsion.

[0180] Explanation of reference numerals in the attached figures

[0181] 1…Lithium-ion battery, 12, 13…Insulating plate, 20…Electrode winding body, 21…Positive electrode, 22…Negative electrode, 23…Separator, 24…Center pin, 25…Positive electrode lead, 26…Negative electrode lead, 31, 32…Foil connector, 33, 34…Comb tooth section, 35, 36…Plate section, 41, 42, 42A, 42B…Connecting section.

Claims

1. A secondary battery, the secondary battery being cylindrical in shape, wherein the electrode winding of the secondary battery is housed in a battery can, the electrode winding having a structure in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked and wound together with a separator in between. The positive electrode has positive electrode active material layers on both sides of the strip-shaped positive electrode foil. The negative electrode has a layer of negative electrode active material on both sides of the strip-shaped negative electrode foil. The electrode winding body has a positive electrode tab at the center of the positive electrode, a negative electrode tab at the winding termination side of the negative electrode, and a flat negative electrode foil tab at the winding start side of the negative electrode. The negative electrode foil contact piece and the negative electrode foil are independent components. The negative electrode foil has a plate-shaped portion and a comb-shaped portion. The plate-shaped portion is joined to the non-covered portion of the negative electrode active material located on the winding start side of the negative electrode, and the comb-shaped portion protrudes from the negative electrode. The plate-shaped portion, together with the negative electrode, is wound 1.5 turns from the starting side of the winding and is disposed on the inner circumference of the electrode winding body. The comb teeth have four band-shaped protrusions, which are composed of two longer band-shaped protrusions and two shorter band-shaped protrusions arranged alternately. The spacing between adjacent strip-shaped protrusions gradually increases from the side where the winding begins. As the plate-shaped portion is wound, the two longer strip-shaped protrusions overlap each other after winding to form a first connecting portion, and the two shorter strip-shaped protrusions overlap each other after winding to form a second connecting portion opposite to the first connecting portion. The length of the first connecting part is greater than the length of the second connecting part. The first connecting part and the second connecting part are folded and welded to the bottom of the battery can.

2. The secondary battery according to claim 1, wherein, The foil of the negative electrode is made of any one of copper, copper-nickel alloy, nickel, zinc, copper-zinc alloy, copper-zinc-nickel alloy, or a composite material thereof.

3. The secondary battery according to claim 1, wherein, The thickness of the foil sheet of the negative electrode is greater than 0.020 mm and less than 0.100 mm.

4. The secondary battery according to claim 1, wherein, The negative electrode active material layer contains silicon dioxide at a content of more than 5 wt% and less than 20 wt%.

5. An electronic device comprising a secondary battery according to any one of claims 1 to 4.

6. An electric tool having a secondary battery according to any one of claims 1 to 4.

Images