Secondary batteries, electronic devices and power tools

Abstract

A secondary battery includes an electrode winding body housed in a battery can. The electrode winding body has a structure formed by stacking and winding strip-shaped positive and negative electrodes separated by a separator. The positive electrode has positive active material layers on both sides of the strip-shaped positive electrode foil, and the negative electrode has negative active material layers on both sides of the strip-shaped negative electrode foil. The electrode winding body has a positive electrode foil tab between the winding start side and the winding end side of the positive electrode, and a negative electrode tab between the winding start side and the winding end side of the negative electrode. The positive electrode foil tab has a plate-shaped portion joined to the winding start side of the positive electrode and a comb-shaped portion protruding from the positive electrode, with the comb-shaped portion serving as a connecting 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 increasingly used in machinery and tools, requiring structures capable of withstanding repeated charge and discharge cycles. During repeated charging and discharging, the inner circumference of the electrode windings within the battery canister may deform and buckle, leading to internal short circuits.

[0003] Patent document 1 discloses the following: by arranging a reinforcing plate on the starting side of the positive electrode winding and then winding it together with the negative electrode and the diaphragm, the strength of the inner periphery of the electrode winding body can be increased.

[0004] Existing technical documents

[0005] Patent documents

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

[0007] However, in Patent Document 1, when the positive electrode tab is welded to the reinforcing plate, the thickness of the positive electrode tab creates a large height difference within the inner circumference of the electrode winding, which can easily lead to internal short circuits. If the thickness of the positive electrode tab is reduced to decrease the height difference within the inner circumference, there is also the problem of heat generation when a large discharge current is applied.

[0008] Therefore, one of the objectives of this invention is to provide a battery that will not cause buckling or internal short circuits even with repeated charging and discharging.

[0009] To address the aforementioned issues, the present invention provides a secondary battery.

[0010] The battery canister contains an electrode winding body, which has a structure formed by stacking and winding strip-shaped positive and negative electrodes separated by a separator.

[0011] The positive electrode has positive electrode active material layers on both sides of the strip-shaped positive electrode foil.

[0012] The negative electrode has a layer of negative electrode active material on both sides of the strip-shaped negative electrode foil.

[0013] The electrode winding body has a positive electrode foil tab between the start and end sides of the winding of the positive electrode, and a negative electrode tab between the start and end sides of the winding of the negative electrode.

[0014] The positive electrode foil tab has a plate-like portion that engages on the winding start side of the positive electrode and a comb-like portion that protrudes from the positive electrode.

[0015] The comb-shaped part serves as the connecting part of the electrode winding body.

[0016] Through at least one embodiment of the present invention, a low-resistance battery can be provided that has no height difference in the inner circumference of the electrode winding body 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 should not be construed as limiting the effects illustrated in this specification. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view of a battery according to one embodiment.

[0018] Figure 2 A to Figure 2 D is a diagram used to illustrate an example of a foil tab.

[0019] Figure 3 A to Figure 3 C is a diagram used to illustrate Example 1.

[0020] Figure 4 A to Figure 4 C is a diagram used to illustrate Example 2.

[0021] Figure 5 A to Figure 5 C is a diagram used to illustrate Example 3.

[0022] Figure 6 A to Figure 6 C is a diagram used to illustrate Example 4.

[0023] Figure 7 A to Figure 7 C is a diagram used to illustrate Example 5.

[0024] Figure 8 A to Figure 8 C is a diagram used to illustrate Comparative Example 1.

[0025] Figure 9 A to Figure 9 C is a diagram used to illustrate variation 1.

[0026] Figure 10 A to Figure 10 C is a diagram used to illustrate variation example 2.

[0027] Figure 11 A to Figure 11 C is a diagram used to illustrate variation example 3.

[0028] Figure 12 A to Figure 12 C is a diagram used to illustrate variation example 4.

[0029] Figure 13 A to Figure 13 C is a diagram used to illustrate variation 5.

[0030] Figure 14 A to Figure 14 C is a diagram used to illustrate variation example 6.

[0031] Figure 15 A to Figure 15 C is a diagram used to illustrate variation 7.

[0032] Figure 16 A to Figure 16 C is a diagram used to illustrate variation example 8.

[0033] Figure 17 This is a connection diagram illustrating a battery pack as an application example of the present invention.

[0034] Figure 18 This is a connection diagram illustrating an application example of the present invention using an electric tool.

[0035] Figure 19 This is a connection diagram used to illustrate an electric vehicle as an application example of the present invention. Detailed Implementation

[0036] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the description will proceed in the following order.

[0037] <1. One implementation method>

[0038] <2. Variations>

[0039] <3. Application Examples>

[0040] The embodiments described below are preferred specific examples of the present invention, and the content of the present invention is not limited to these embodiments.

[0041] 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 or batteries other than cylindrical shapes can also be used.

[0042] <1. One implementation method>

[0043] 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, wherein the electrode winding body 20 is housed inside the battery can 11.

[0044] Specifically, the lithium-ion battery 1 has a pair of insulators 12 and 13 and an electrode winding 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 positive temperature coefficient thermal-resistor (PTC) and reinforcing components.

[0045] [Battery can]

[0046] The battery can 11 is the main component for housing the electrode winding 20. The battery can 11 is, for example, a cylindrical container open at one end and closed at the other. That is, the battery can 11 has an open end (open end 11N). The battery can 11 contains, for example, any one or more metallic materials such as iron, aluminum, and their alloys. Additionally, the surface of the battery can 11 may be plated with, for example, any one or more metallic materials such as nickel.

[0047] [Insulating board]

[0048] Insulating plates 12 and 13 have a winding axis direction that is approximately perpendicular to the electrode winding body 20. Figure 1 A sheet-like component (in the vertical direction). Insulating plates 12 and 13 are configured to sandwich the electrode winding 20 between them. Polyethylene terephthalate (PET), polypropylene (PP), bakelite, etc., are used as materials for insulating plates 12 and 13. Bakelite includes paper bakelite or cloth bakelite made by coating phenolic resin onto paper or cloth and then heating it.

[0049] [Riveting Structure]

[0050] At the open end 11N of the battery can 11, at the bent portion 11P, the battery cover 14 and the safety valve mechanism 30 are riveted together via a washer 15 to form a riveting structure 11R (curled structure). Thus, with the electrode winding body 20 and the like housed inside the battery can 11, the battery can 11 is sealed.

[0051] [Battery cover]

[0052] The battery cover 14 is primarily 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, for example, is made of the same material as the battery can 11. The central region of the battery cover 14, for example, faces... Figure 1 The vertical direction is prominent. On the other hand, the area outside the central area of ​​the battery cover 14 (the peripheral area) comes into contact with, for example, the safety valve mechanism 30.

[0053] [washer]

[0054] The gasket 15 is a component that seals the gap between the bent portion 11P (also called the coiled portion 11P) of the battery can 11 and the battery cover 14 through a space between the bent portion 11P of the battery can 11 and the battery cover 14. For example, asphalt can be coated on the surface of the gasket 15.

[0055] 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 allows for sufficient sealing of the gap between the bent portion 11P and the battery cover 14 while simultaneously isolating the battery canister 11 and the battery cover 14 from each other.

[0056] [Safety Valve Mechanism]

[0057] When the pressure inside the battery canister 11 rises (internal pressure), the safety valve mechanism 30 releases the internal pressure mainly by releasing the sealed state of the battery canister 11 as needed. The increase in internal pressure in the battery canister 11 can be caused by, for example, gases generated during charging and discharging due to the decomposition reaction of the electrolyte.

[0058] [Electrode winding]

[0059] 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 in between, and housed in a battery can 11 while immersed in electrolyte. Although not shown in the diagram, the positive electrode 21 and negative electrode 22 are formed by forming a positive electrode active material layer and a negative electrode active material layer on one or both sides of the positive electrode foil and 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 the negative electrode 22 while allowing lithium ions to move.

[0060] A space (central space 20C) is provided at the center of the electrode winding body 20, which is generated 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 Additionally, center pin 24 can be omitted.

[0061] 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 conductive materials 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 conductive materials such as nickel. The negative lead 26 is electrically connected to the battery canister 11.

[0062] The detailed structure and materials of the positive electrode 21, negative electrode 22, separator 23, and electrolyte will be described later.

[0063] [positive electrode]

[0064] 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).

[0065] Lithium-containing composite oxides, for example, have layered rock salt or spinel-type crystal structures. Lithium-containing phosphate compounds, for example, have olivine-type crystal structures.

[0066] The positive electrode binder contains synthetic rubber or polymeric compounds. Synthetic rubbers include styrene-butadiene rubber, fluorinated rubber, and ethylene propylene diene monomer (EPDM) rubber, etc. Polymeric compounds include polyvinylidene fluoride (PVdF) and polyimide, etc.

[0067] The positive electrode conductive agent is a carbon material such as graphite, carbon black, acetylene black, or Ketjen black. Alternatively, the positive electrode conductive agent can also be a metallic material or a conductive polymer.

[0068] [negative electrode]

[0069] The surface of the negative electrode foil is preferably roughened. This is because the adhesion between the negative electrode active material layer and the negative electrode foil is improved through a so-called anchoring effect. 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.

[0070] 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.

[0071] Anode materials may include carbon materials. This is because the change in crystal structure during lithium insertion and extraction is very small, thus allowing for a stable high energy density. Furthermore, since the carbon material also acts as a conductive agent in the anode, the conductivity of the active material layer is improved.

[0072] 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.

[0073] Furthermore, negative electrode materials may include, for example, metallic materials. Examples of metallic materials include Li (lithium), Si (silicon), Sn (tin), Al (aluminum), Zn (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 (Li4Ti5O) 12 ).

[0074] It should be noted that, for high capacity, the negative electrode material preferably contains silicon-containing compounds such as silicon oxide or silicon alloys, or silicon monomers. For example, the silicon oxide content in the negative electrode active material layer is preferably between 5 wt% and 20 wt%. This is because if the content is too low, the high capacity effect cannot be achieved; if it is too high, silicon expansion will impair battery characteristics. It should also be noted that the content of silicon alloys or silicon monomers is similarly affected.

[0075] 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 lower, even using the same positive electrode active material, the amount of lithium extracted per unit mass increases. This results in a higher energy density.

[0076] [Septum]

[0077] 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.

[0078] The separator 23 may contain a resin layer on one or both sides of the porous membrane that serves as the substrate layer. This is because it can improve the adhesion between the separator 23 and each of the positive electrode 21 and the negative electrode 22, thereby suppressing the deformation of the electrode winding 20.

[0079] The resin layer contains resins such as PVdF. When forming this resin layer, a solution containing the resin 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 dried after being immersed in the solution. From the viewpoint 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.

[0080] Electrolyte

[0081] Electrolytes contain solvents and electrolyte salts, and may also contain additives as needed. Solvents can be 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.

[0082] 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; from the viewpoint 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.

[0083] [Methods for manufacturing lithium-ion batteries]

[0084] Next, the manufacturing method of the secondary battery will be explained. First, in the case of producing positive electrode 21, a positive electrode mixture is prepared by mixing positive electrode active material, positive electrode binder, and positive electrode conductive agent. Next, a paste-like positive electrode mixture slurry is prepared by dispersing the positive electrode mixture in an organic solvent. 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 positive electrode 21.

[0085] When making the negative electrode 22, the same steps as those for the positive electrode 21 described above are followed.

[0086] 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, the positive electrode 21 and the negative electrode 22 are stacked in layers with the separator 23 in between, and then they are wound up. Fixing tape is attached to the outermost circumferential surface of the separator 23 to form the electrode winding body 20.

[0087] Next, with the insulator in contact with the exposed side of the negative electrode lead 26 of the electrode winding 20, the electrode winding 20 is housed inside the battery can 11, and the bottom of the can is connected to the negative electrode lead 26 using a welding method. Then, an insulator is also placed on the exposed side of the positive electrode lead 25 of the electrode winding 20, and one end of the positive electrode lead 25 is connected to the safety valve mechanism 30 using a welding method.

[0088] Next, the battery can 11 is machined using a crimping machine (grooving machine) to form a recess on the battery can 11. Next, electrolyte is injected into the interior of the battery can 11 and impregnates the electrode winding body 20. Next, the battery cover 14 and the safety valve mechanism 30, along with the gasket 15, are housed inside the battery can 11.

[0089] Finally, as Figure 1As shown, at the open end 11N of the battery can 11, the battery cover 14 and the safety valve mechanism 30 are riveted together via a gasket 15 to form a riveting structure 11R.

[0090] Example

[0091] The present invention will now be specifically described using the battery 1 manufactured as described above, based on embodiments regarding the battery's internal resistance, short-circuit incidence rate after low-temperature cycling test and drop test, and buckling incidence rate. It should be noted that the present invention is not limited to the embodiments described below.

[0092] The battery has dimensions of 18650 (18mm diameter, 65mm height) and a rated capacity of 3000mAh. The positive electrode foil 21A is made of Al and has a thickness of 0.015mm. The negative electrode foil 22A is made of Cu and has a thickness of 0.015mm. The separator 23 is biaxially stretched polyethylene and has a thickness of 0.010mm. In all examples and comparative examples, the negative electrode active material contains carbon and silicon. Specifically, the negative electrode active material contains carbon as the main material, and the silicon oxide content is 15wt% in the examples and comparative examples.

[0093] The foil tab 35 shown below is equivalent to the positive electrode. Figure 1 The positive lead 25 and the negative electrode tab 52 are equivalent to... Figure 1 The negative electrode lead 26. In the embodiments and comparative examples, in addition to the foil tabs 35 and 52 located between the winding start side and winding end side of the positive and negative electrodes, foil tabs 31 and 32 are sometimes also present on the winding start side of the positive and negative electrodes. Hereinafter, the foil tabs 35 of the positive electrode and 32 of the negative electrode will be used as examples for explanation.

[0094] Hereinafter, the area on the surface of the positive electrode foil 21A covered with the positive electrode active material layer will be referred to as the positive electrode active material covered portion 21B, and the uncovered area 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 the negative electrode active material layer will be referred to as the negative electrode active material covered portion 22B, and the uncovered area will be referred to as the negative electrode active material uncovered portion 22C.

[0095] To gain a basic understanding of the positive electrode tab 35, the tabs 31 and 32 are explained below. The positive electrode 21 or negative electrode 22 has a positive electrode tab 31 or a negative electrode tab 32 on the winding start side. The negative electrode tab 32 is, for example, as shown below. Figure 2 As shown in Figure A, the foil tab 32 has a flat plate shape and is composed of a plate-shaped portion 39 and a comb-tooth portion 34. The plate-shaped portion 39 of the foil tab 32 has a width of 24 mm, which is larger than that of existing tabs, and serves to collect current from the negative electrode 22. The foil tab 32 has a comb-tooth portion 34 at its end.

[0096] Figure 2 A to Figure 2 D shows an example of the structure of the foil tab 32 and an example of the foil tab 32 being wound together with the negative electrode 22. Figure 2 In A, the comb tooth 34 is a strip-shaped protrusion forming a comb shape with a width of 3mm and a length of 5mm. Figure 2 The spacing of the strip-shaped protrusions in the comb tooth section 34 of 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 due to winding delay is approximately within ±1mm, which does not cause problems in welding to the can bottom and safety valve. The spacing of the strip-shaped protrusions in the foil tab 32 is set to gradually increase from the winding start side so that the strip-shaped protrusions of the comb tooth section 34 become a concentrated shape when winding the foil tab 32. Figure 2 As shown in Figure B, for example, the plate-shaped portion 39 of the foil tab 32 of the negative electrode is joined to the winding start side of the negative electrode 22, i.e., the non-covered portion 22C of the active material of the negative electrode, through three welding points 61 (the parts with dotted patterns in the figure). At this time, the foil tab 32 is configured such that the comb-like portion 34 protrudes from the negative electrode 22. It should be noted that the foil tab 31 of the positive electrode can also adopt the same structure as the foil tab 32 of the negative electrode.

[0097] The foil tab 32 is wound together with the negative electrode 22, as follows: Figure 2 As shown in Figure C, the comb-like teeth 34 of the foil tab 32 are staggered and overlap, converging at one point to form a connecting portion 42 of the foil tab 32. The connecting portion 42 engages with the bottom of the battery can 11. Figure 2 A and Figure 2 The foil tab 32 of B has three strip-shaped protrusions on its comb tooth portion 34. Figure 2 In section C, the plate-shaped portion 39 of the foil tab 32 is wound twice, and the connecting portion 42 forms a structure with three overlapping strip-shaped protrusions. The wound foil tab 32 is a reinforcing material for the inner periphery of the electrode winding body 20, which can prevent the inner periphery of the electrode winding body 20 from buckling or deforming during the charging and discharging of the battery 1.

[0098] The comb teeth of the negative electrode foil tab 32 can also be divided into four, six, or more comb teeth 34, for example, in this case, such as Figure 2 As shown in Figure D, during winding, the comb teeth 34 of the foil tab 32 converge at two locations, forming two opposing connecting portions 42A and 42B. In this case, if longer and shorter strip-shaped protrusions (not shown) are alternately arranged on the comb teeth 34 of the negative electrode foil tab 32 and then wound, the longer strip-shaped protrusions overlap with each other and the shorter strip-shaped protrusions overlap with each other, as shown in Figure D. Figure 2As shown in Figure D, a longer connecting portion 42A and a shorter connecting portion 42B are formed on the foil tab 32. By changing the lengths of the two connecting portions 42A and 42B, it is possible to fold and weld them to the bottom of the can.

[0099] 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-like portions of the foil tab 31 are joined by welding on the winding start side of the positive electrode, i.e., the non-covered portion 21C of the active material of the positive electrode. The wound foil tab 31 is a reinforcing material for the inner periphery of the electrode winding body 20, and can prevent the inner periphery of the electrode winding body 20 from buckling or deforming during the charging and discharging of the battery 1.

[0100] Due to the thickness requirements of the foil tabs 31 and 32 as reinforcing materials for the inner periphery of the electrode winding body 20, and the structural limitations within 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 foil tab 32 of the negative electrode is preferably any one of copper, copper-nickel alloy, nickel, zinc, copper-zinc alloy, copper-zinc-nickel alloy, or composite materials thereof. Furthermore, the number of turns of the foil tab 32 is preferably more than one turn and less than four turns.

[0101] Materials used for the foil tab 31 as the positive electrode include, for example, aluminum, titanium, and stainless steel (SUS). SUS304 dissolves after heating and 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 and aging in a 4.2V system using LCO or NCA positive electrodes. Thus, regarding SUS, the material can be appropriately selected according to the battery voltage.

[0102] The positive electrode 21 shown below has a foil tab 35 between the winding start side and the winding end side. The foil tab 35 of the positive electrode has, for example, a flat plate shape, consisting of a plate-like portion and a comb-like portion 36. The plate-like portion of the foil tab 35 has a wider width than conventional tabs, serving to collect current from the positive electrode. The foil tab 35 has a comb-like portion 36 at its end, consisting of two strip-like protrusions.

[0103] One of the strip-shaped protrusions of the comb portion 36 of the foil tab 35 is a comb shape with a width of 6 mm and a length of 7 mm. The interval between two strip-shaped protrusions is approximately 20 mm, designed so that when the foil tab 35 is wound together with the positive electrode 21, the strip-shaped protrusions of the comb portion 36 form a concentrated shape. The plate-shaped portion of the foil tab 35 of the positive electrode is joined to the non-covered portion 21C of the active material of the positive electrode at approximately the middle position of the positive electrode 21 by welding. At this time, the foil tab 35 is arranged such that the comb portion 36 protrudes from the positive electrode 21. The material of the foil tab 35 of the positive electrode can be the same as that of the foil tab 31. The thickness of the foil tab 35 is preferably 0.020 mm or more and 0.100 mm or less. More preferably, the thickness of the foil tab 35 is 0.030 mm or more and 0.080 mm or less.

[0104] The foil tab 35 is wound together with the positive electrode 21. The strip-shaped protrusions of the comb portion 36 of the foil tab 35 are staggered and overlap, converging at one point to form a connecting portion 43 of the foil tab 35. The connecting portion 43 engages with the safety valve mechanism 30. The foil tab 35 has two strip-shaped protrusions on the comb portion 36. The plate-shaped portion of the foil tab 35 is wound around once, and the connecting portion 43 forms a structure where the two strip-shaped protrusions overlap. The wound foil tab 35 is a reinforcing material for the inner circumference of the electrode winding body 20, preventing buckling or deformation of the inner circumference of the electrode winding body 20 during charging and discharging of the battery 1.

[0105] The foil tab 35, located approximately in the center of the positive electrode 21, has a thickness of 0.05 mm and a width of 6 mm for the strip-shaped protrusions of the comb portion 36. It is made of Al. The foil tab 35, located approximately in the center of the positive electrode 21, and the uncovered portion 21C of the active material of the positive electrode to which the foil tab 35 is attached, are covered by an insulating tape 51. The tab 52, located approximately in the center of the negative electrode 22, has a thickness of 0.08 mm and a width of 3 mm. It is made of Cu. The tab 52, located approximately in the center of the negative electrode 22, and the uncovered portion 22C of the active material of the negative electrode to which the tab 52 is attached, are covered by an insulating tape 51.

[0106] Furthermore, in Examples 2 to 5, the foil tab 31 located on the winding start side of the positive electrode 21 has a thickness of 0.05 mm, the strip-shaped protrusion of the comb portion 33 has a width of 3 mm, and the material is Al. The foil tab 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 tab 31 is attached are covered by an insulating tape 51. The foil tab 32 located on the winding start side of the negative electrode 22 has a thickness of 0.04 mm, the strip-shaped protrusion of the comb portion 34 has a width of 3 mm, and the material is Cu.

[0107] In Comparative Example 1, the tab 55, located approximately in the middle of the positive electrode 21, has a thickness of 0.1 mm and a width of 6 mm, and is made of Al. The tab 54, located on the winding start side of the negative electrode 22, has a thickness of 0.08 mm and a width of 3 mm, and is made of CuNi. The tab 53, located on the winding end side of the negative electrode 22, has a thickness of 0.08 mm and a width of 3 mm, and is made of CuNi.

[0108] The thicknesses of tabs 52, 53, 54, and 55, foil tab 35, and foil tabs 31 and 32 were measured using a micrometer (Mitutoyo MDC-25MX).

[0109] Figure 3 A to Figure 8 A( Figures 3 to 8 A) In each diagram, the upper side shows a schematic diagram of the positive electrode 21 before winding, and the lower side shows a schematic diagram of the negative electrode 22 before winding. The right side of each diagram is the winding start side, and the left side of each diagram is the winding end side. Figure 3 B to Figure 8 B( Figure 3 A to Figure 8 B) in each of the diagrams A shows the situation where... Figure 3 A to Figure 8 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 23. 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 8 C( Figure 3 A to Figure 8 In each of the diagrams C, C) represents... Figure 3 B to Figure 8 A schematic diagram of the electrode winding body 20 of B housed in the battery canister 11 as battery 1.

[0110] [Example 1]

[0111] like Figure 3 As shown in Figure A, a foil tab 35 is positioned approximately in the center of the positive electrode 21, and a tab 52 is positioned approximately in the center of the negative electrode 22. The comb-like portion 36 of the foil tab 35 consists of two strip-shaped protrusions. Figure 3 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped through the diaphragm 23, and wound in such a way that the two strip-shaped protrusions of the comb-tooth portion 36 overlap and converge at a connecting portion 43. The negative electrode tab 52 is wound once. The foil tab 35 is made of Al, and the tab 52 is made of Cu. Figure 3 As shown in Figure C, an electrode winding 20 with foil tabs 35 and tabs 52 joined together is disposed within the battery canister 11. The negative electrode active material contains 15 wt% silicon oxide.

[0112] [Example 2]

[0113] like Figure 4 As shown in Figure A, a foil tab 35 is positioned approximately in 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 36 of the foil tab 35 consists of two strip-shaped protrusions, and the comb portion 33 of the foil tab 31 consists of six strip-shaped protrusions. An electrode tab 52 is positioned approximately in the center of the negative electrode 22, and a foil tab 32 is positioned on the winding start side of the negative electrode 22. The comb portion 34 of the foil tab 32 consists of six 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. Regarding the foil tab 35, it is wound in such a way that the two strip-shaped protrusions of the comb teeth 36 are overlapped and concentrated at a connecting portion 43. The foil tab 35 of the positive electrode is wound once. Furthermore, regarding each foil tab 31 and foil tab 32, it is wound in such a way that the six strip-shaped protrusions of the comb teeth 33 and 34 are overlapped every other one and concentrated at two connecting portions 41, 41 and two connecting portions 42A, 42B. The foil tab 31 of the positive electrode is wound 2.5 times, and the foil tab 32 of the negative electrode is wound 2.5 times. Figure 4 As shown in Figure C, an electrode winding 20, with foil tabs 35, 52, 31, and 32 joined together, is disposed within the battery canister 11. The negative electrode active material contains 15 wt% silicon oxide.

[0114] [Example 3]

[0115] like Figure 5 As shown in Figure A, a foil tab 35 is positioned approximately in 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 36 of the foil tab 35 consists of two strip-shaped protrusions, and the comb portion 33 of the foil tab 31 consists of four strip-shaped protrusions. An electrode tab 52 is positioned approximately in the center of the negative electrode 22, and a foil tab 32 is positioned on the winding start side of the negative electrode 22. The comb portion 34 of the foil tab 32 consists of four strip-shaped protrusions. Figure 5 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped through the diaphragm 23. Regarding the foil tab 35, it is wound in such a way that the two strip-shaped protrusions of the comb teeth 36 are overlapped and concentrated at a connecting portion 43. The foil tab 35 of the positive electrode is wound once. Furthermore, regarding each foil tab 31 and foil tab 32, it is wound in such a way that the four strip-shaped protrusions of the comb teeth 33 and 34 are overlapped every other one and concentrated at two connecting portions 41, 41 and two connecting portions 42A, 42B. The foil tab 31 of the positive electrode is wound 1.5 times, and the foil tab 32 of the negative electrode is wound 1.5 times. Figure 5 As shown in Figure C, an electrode winding 20, with foil tabs 35, 52, 31, and 32 joined together, is disposed within the battery canister 11. The negative electrode active material contains 15 wt% silicon oxide.

[0116] [Example 4]

[0117] like Figure 6 As shown in Figure A, a foil tab 35 is positioned approximately in the middle 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 36 of the foil tab 35 consists of two strip-shaped protrusions, and the comb portion 33 of the foil tab 31 consists of three strip-shaped protrusions. An electrode tab 52 is positioned approximately in the middle of the negative electrode 22, and a foil tab 32 is positioned on the winding start side of the negative electrode 22. The comb portion 34 of the foil tab 32 consists of three strip-shaped protrusions. Figure 6 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped through the diaphragm 23. Regarding the foil tab 35, it is wound in such a way that the two strip-shaped protrusions of the comb teeth 36 are overlapped and concentrated into a connecting portion 43. The foil tab 35 of the positive electrode is wound once. Furthermore, regarding each foil tab 31 and foil tab 32, it is wound in such a way that the three strip-shaped protrusions of the comb teeth 33 and 34 are overlapped and concentrated into a connecting portion 41 and a connecting portion 42. The foil tab 31 of the positive electrode is wound twice, and the foil tab 32 of the negative electrode is wound twice. Figure 6 As shown in Figure C, an electrode winding 20, with foil tabs 35, 52, 31, and 32 joined together, is disposed within the battery canister 11. The negative electrode active material contains 15 wt% silicon oxide.

[0118] [Example 5]

[0119] like Figure 7 As shown in Figure A, a foil tab 35 is positioned approximately in the middle 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 36 of the foil tab 35 consists of two strip-shaped protrusions, and the comb portion 33 of the foil tab 31 also consists of two strip-shaped protrusions. An electrode tab 52 is positioned approximately in the middle of the negative electrode 22, and a foil tab 32 is positioned on the winding start side of the negative electrode 22. The comb portion 34 of the foil tab 32 consists of two strip-shaped protrusions. Figure 7 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped through the diaphragm 23. Regarding the foil tab 35, it is wound in such a way that the two strip-shaped protrusions of the comb teeth 36 are overlapped and concentrated into a connecting portion 43. The foil tab 35 of the positive electrode is wound once. Furthermore, regarding each foil tab 31 and foil tab 32, it is wound in such a way that the two strip-shaped protrusions of the comb teeth 33 and 34 are overlapped and concentrated into a connecting portion 41 and a connecting portion 42. The foil tab 31 of the positive electrode is wound once, and the foil tab 32 of the negative electrode is wound once. Figure 7 As shown in Figure C, an electrode winding 20, with foil tabs 35, 52, 31, and 32 joined together, is disposed within the battery canister 11. The negative electrode active material contains 15 wt% silicon oxide.

[0120] [Comparative Example 1]

[0121] like Figure 8 As shown in Figure A, a tab 55 is positioned approximately in the middle of the positive electrode 21, a tab 54 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. Figure 8 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped and wound together with the diaphragm 23 in between. Figure 8 As shown in Figure C, an electrode winding 20 with tabs 53, 54, and 55 attached is disposed within the battery canister 11. The negative electrode active material contains 15 wt% silicon oxide.

[0122] [evaluate]

[0123] Regarding battery 1 in the above example, the internal resistance of the battery was determined, the short-circuit rate was determined by a drop test after a low-temperature cycling test, and the buckling rate was determined by CT imaging. A comprehensive evaluation was conducted based on these results. The battery's internal resistance, low-temperature cycling test, drop test, and CT imaging are as follows.

[0124] <Battery internal resistance>

[0125] The internal resistance of the battery is determined by measuring the AC impedance at a frequency of 1 kHz.

[0126] <Low Temperature Cycling Test>

[0127] Ambient temperature: 0℃

[0128] Charging: CC / CV, 4.25V / 1C, 100mA cut

[0129] Discharge: 2C, 2Vcut (Recharge begins when the battery cell temperature reaches 0℃ after discharge).

[0130] Cycle count: The number of cycles in which the discharge rate is gradually reduced from a baseline of 30% capacity retention, and finally maintained at a low rate (0.5C) until the capacity retention reaches 30%.

[0131] If the maintenance rate relative to the initial discharge capacity is less than 30%, reduce the discharge rate to 1C; if it is also less than 30%, reduce it to 0.5C, and continue testing until it is less than 30%.

[0132] <Fall Test>

[0133] Based on the "Guideline for Safety Evaluation of Lithium Secondary Batteries" (SBA G1101), some modifications were made. Specifically, the drop test specified in SBA G1101 is a test in which the battery is dropped 1.9m from a height onto concrete 10 times. However, in this evaluation, the number of drops was set to 20, and the probability of short circuit occurrence when n=10 was calculated.

[0134] <CT scan>

[0135] Following a drop test after low-temperature cycling, the inner circumference of the electrode winding was observed using X-ray CT imaging. The proportion of cells that caused buckling was taken as the buckling incidence rate. Ten tests were conducted.

[0136] [Table 1]

[0137]

[0138] In Examples 1 to 5, the short-circuit occurrence rate and buckling occurrence rate were 0% or 10%, and the overall evaluation was OK. In contrast, in Comparative Example 1, these were higher values, and the overall evaluation was NG. In particular, as shown in Examples 2 to 5, when foil tabs were present on the winding start side of the positive electrode 21 and the winding start side of the negative electrode, the internal resistance of the battery was lower compared to Example 1 or Comparative Example 1, which did not have foil tabs. In Examples 1 to 5, the inner circumference of the electrode winding body did not deform and remained round. In contrast, in Comparative Example 1, the inner circumference of the electrode winding body deformed and did not remain round. As can be seen from Table 1, when a foil tab 35 of the positive electrode is present between the winding start side and the winding end side of the positive electrode (approximately the middle position of the positive electrode), and the foil tab 35 has a comb portion 36 protruding from the positive electrode 21, and the comb portion 36 is used as the connecting portion 43 of the electrode winding body 20, the battery 1 will not buckle or internal short circuit even with repeated charging and discharging.

[0139] <2. Variations>

[0140] 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 made based on the technical concept of the present invention.

[0141] In modifications 5-8, a tab 56 is further provided at approximately one-third of the length from the winding termination side of the positive electrode 21 towards the winding start side. The tab 56 is 0.1 mm thick, 5 mm wide, and made of aluminum. The tab 56, located approximately in the middle of the positive electrode 21, and the non-covered portion 21C of the active material of the positive electrode to which the tab 56 is attached are covered by an insulating tape 51. The thickness of the tab 56 was measured using a micrometer (Mitutoyo MDC-25MX). The foil tab 37 shown in the modification is the same as the foil tab 35, except for the spacing of the strip-shaped protrusions of the comb portion 38.

[0142] Figure 9 A to Figure 16 A( Figures 9 to 16 A) In each diagram, the upper side shows a schematic diagram of the positive electrode 21 before winding, and the lower side shows a schematic diagram of the negative electrode 22 before winding. The right side of each diagram is the winding start side, and the left side of each diagram is the winding end side. Figure 9 B to Figure 16 B( Figure 9 A to Figure 16 B) of each diagram in A represents the... Figure 9 A to Figure 16 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 9 C to Figure 16 C( Figure 9 A to Figure 16 The C in each of the diagrams C) are respectively... Figure 9 B to Figure 16 A schematic diagram of the electrode winding body 20 of B being housed in the battery canister 11 to form battery 1.

[0143] [Variations 1-4]

[0144] The negative electrodes of variations 1 to 4 are structures in which an electrode tab 53 is added to the winding termination side of the negative electrode in examples 2 to 5. Figure 9 This indicates that in Example 2, a modified version 1 was created by adding a tab 53. Figure 10 This indicates that in Example 3, a modified example 2 was created by adding a tab 53. Figure 11 This indicates that in Example 4, a modified version 3 was added with a tab 53. Figure 12 This refers to Modification 4, in which a tab 53 is added to Example 5. The tab 53 of the negative electrode added in Modifications 1 to 4 is welded together with the connecting part 42 and the like to the bottom of the battery can.

[0145] [Variation Example 5]

[0146] like Figure 13 As shown in Figure A, a foil tab 37 is disposed at approximately one-third of the total length from the winding start side to the winding end side of the positive electrode 21, a tab 56 is disposed at approximately one-third of the total length from the winding end side to the winding start side of the positive electrode 21, and a foil tab 31 is disposed at the winding start side of the positive electrode 21. The comb portion 38 of the foil tab 37 consists of two strip-shaped protrusions, and the comb portion 33 of the foil tab 31 consists of six strip-shaped protrusions. A tab 52 is disposed at approximately one-third of the total length from the winding start side to the winding end side of the negative electrode 22, a tab 53 is disposed at the winding end side of the negative electrode 22, and a foil tab 32 is disposed at the winding start side of the negative electrode 22. The comb portion 34 of the foil tab 32 consists of six strip-shaped protrusions. Figure 13 As shown in Figure B, the positive electrode 21 and the negative electrode 22 are overlapped with the diaphragm 23 in between. Regarding the foil tab 37, the two strip-shaped protrusions of the comb portion 38 are overlapped and wound around a connecting portion 45. The foil tab 37 of the positive electrode is wound once. Furthermore, the foil tabs 31 and 32 are the same as in Example 2. Figure 13 As shown in C, the electrode winding body 20, which consists of foil tabs 37, tabs 52, 53, 56 and foil tabs 31, 32, is disposed inside the battery canister 11.

[0147] [Variation Example 6]

[0148] like Figure 14 A to Figure 14 As shown in C, except that the number of band-shaped protrusions in the comb portions 33 and 34 of the foil tabs 31 and 32 are four respectively, they are the same as in Modified Example 5. The foil tabs 31 and 32 are the same as in Example 3.

[0149] [Variation Example 7]

[0150] like Figure 15 A to Figure 15 As shown in C, except that the number of strip-shaped protrusions in the comb portions 33 and 34 of the foil tabs 31 and 32 are three respectively, they are the same as in Modified Example 5. The foil tabs 31 and 32 are the same as in Example 4.

[0151] [Variation Example 8]

[0152] like Figure 16 A to Figure 16 As shown in C, except that the number of band-shaped protrusions in the comb portions 33 and 34 of the foil tabs 31 and 32 are two each, they are the same as in Modified Example 5. The foil tabs 31 and 32 are the same as in Example 5.

[0153] Modifications 1 to 4 have the same buckling rate as Examples 2 to 5, and it is predicted that the resistance value of the electrode winding will be lower compared to Examples 2 to 5. Modifications 5 to 8 have the same buckling rate as Examples 2 to 5, and it is predicted that the resistance value of the electrode winding will be lower compared to Modifications 1 to 4.

[0154] Battery 1 has a size of 18650, but other sizes are also possible. Battery 1 has a rated capacity of 3000mAh, but other values ​​are also possible. The thicknesses of the positive electrode foil 21A, negative electrode foil 22A, and separator 23 are not necessarily the values ​​described above. The number of strip-shaped protrusions in the comb portions 33 and 34 is not limited to the embodiment and can also be other values.

[0155] <3. Application Examples>

[0156] (1) Battery pack

[0157] Figure 17This is a block diagram illustrating a circuit structure 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 battery assembly 301, a switching unit 304 including a charging control switch 302a and a discharging control switch 303a, a current sensing resistor 307, a temperature sensing element 308, and a control unit 310. The control unit 310 controls each device, thereby enabling charging and discharging control in case of abnormal heat generation, or calculating or correcting the remaining capacity of the battery pack 300.

[0158] When the battery pack 300 is charging, 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.

[0159] The battery pack 301 is constructed by connecting multiple secondary batteries 301a in series and / or parallel. Figure 17 The example shown is a configuration where six secondary batteries 301a are connected in a 2-in-parallel, 3-in-series (2P3S) configuration, but any connection method is possible.

[0160] Temperature detection unit 318 is connected to temperature detection element 308 (e.g., a thermistor) to measure the temperature of battery pack 301 or battery stack 300, and provides the measured temperature to control unit 310. Voltage detection unit 311 measures the voltage of battery pack 301 and each secondary battery 301a constituting battery pack 301, performs A / D conversion on the measured voltage, and provides it to control unit 310. Current measurement unit 313 measures the current using current detection resistor 307 and provides the measured current to control unit 310.

[0161] 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 any one of the secondary batteries 301a falls below the overcharge detection voltage or the over-discharge detection voltage, or when a large current flows rapidly, the switch control unit 314 sends a shut-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.

[0162] After the charging control switch 302a or the discharging control switch 303a is turned off, charging or discharging can be performed solely through diode 302b or diode 303b. These charging and discharging switches can utilize semiconductor switches such as MOSFETs. In this case, the parasitic diode of the MOSFET functions as diodes 302b and 303b. It should be noted that... Figure 17 In the middle, the switch part 304 is provided on the + side, but it can also be provided on the - side.

[0163] The memory 317 is composed of RAM and ROM, and may include, 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. Furthermore, it can be rewritten as needed. In addition, by storing the full charge capacity of the secondary battery 301a, the remaining capacity can be calculated in coordination with the control unit 310.

[0164] (2) Electronic devices

[0165] The battery 1 described in the above-described embodiments or examples of the present invention can be mounted in electronic devices, electric conveying devices, energy storage devices, or other equipment to supply power.

[0166] 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, electrically powered transmission equipment, energy storage devices, power tools, and electrically powered drones, which will be described later, can also be broadly included in the category of electronic devices.

[0167] Examples of electric conveying equipment include electric vehicles (including hybrid vehicles), electric motorcycles, electric-assisted bicycles, electric buses, electric trolleys, automated guided vehicles (AGVs), and railway vehicles. Additionally, electric passenger aircraft or electric unmanned aerial vehicles (UAVs) for transportation are also included. The secondary battery involved in this invention can be used not only as a power source for driving these devices, but also as an auxiliary power source, a power source for energy regeneration, etc.

[0168] As energy storage devices, examples include commercial or residential energy storage modules, and power storage devices for use in buildings such as residences, buildings, and offices, or for power generation equipment.

[0169] (3) Power tools

[0170] Reference Figure 18 As an example of an electric screwdriver to which the present invention can be applied, a brief description will be given. The electric screwdriver 431 is equipped with a motor 433 that transmits rotational power to a shaft 434 and a user-operated trigger switch 432. By operating the trigger switch 432, screws or the like are driven into an object via the shaft 434.

[0171] The battery pack 430 and the motor control unit 435 are housed in the lower frame of the handle of the electric screwdriver 431. The battery pack 430 can be the aforementioned battery pack 300. The battery pack 430 can be built into the electric screwdriver 431 or can be freely installed and removed. The battery pack 430 can be installed in a charging device either built into the electric screwdriver 431 or removed.

[0172] The battery pack 430 and the motor control unit 435 each have a microcomputer. The battery pack 430 supplies power 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 also cut off the power supply to the load (motor 433, etc.) in case of over-discharge.

[0173] (4) Energy storage system for electric vehicles

[0174] As an example of applying the present invention to an energy storage system for electric vehicles, Figure 19 The diagram schematically illustrates a structural 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 an engine, or electricity temporarily stored in a battery, to drive a vehicle via an electric drive conversion device.

[0175] 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 is cylindrical, square, or laminated.

[0176] 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) via the vehicle control unit 609. These sensors 610 include speed sensors, acceleration sensors, and engine speed sensors.

[0177] 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 receives power from an external power source via the charging port 611 of the hybrid vehicle 600 and is capable of storing electricity. Such an HV vehicle is called a plug-in hybrid electric vehicle (PHV or PHEV).

[0178] The above explanation uses a series hybrid vehicle as an example, but the 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 invention can also be applied to electric vehicles (EVs or BEVs) and fuel cell vehicles (FCVs) that operate solely on a drive motor without an engine.

[0179] Explanation of reference numerals in the attached figures

[0180] 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 tabs; 33, 34: Comb teeth; 35, 37: Foil tabs; 36, 38: Comb teeth; 39: Plate-shaped part; 41, 42, 42A, 42B, 43: Connecting part; 51: Insulating tape; 52, 53, 54: Negative electrode tabs; 55, 56: Positive electrode tabs.

Claims

1. A secondary battery, The battery canister contains an electrode winding body, which has a structure formed by stacking and winding strip-shaped positive and negative electrodes separated by a separator. 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 foil tab between the winding start side and the winding end side of the positive electrode, and a negative electrode tab between the winding start side and the winding end side of the negative electrode. The positive electrode foil tab has a plate-shaped portion that engages with the winding start side of the positive electrode and a comb-like portion that protrudes from the positive electrode. The comb-like portion serves as the connecting part of the electrode winding body. The band-shaped protrusions of the comb teeth overlap at least partially during winding due to the delay in winding. The plate-shaped portion overlaps during winding due to the winding delay.

2. The secondary battery according to claim 1, wherein, The surface of the positive electrode foil includes the area covered by the positive electrode active material layer, i.e., the positive electrode active material covered portion, and the area not covered by the positive electrode active material layer, i.e., the positive electrode active material uncovered portion. The plate-shaped portion of the positive electrode foil tab is located approximately in the middle of the positive electrode and is joined to the non-covered portion of the positive electrode active material by welding.

3. The secondary battery according to claim 1, wherein, The positive and negative electrodes each have a flat foil tab on their respective winding start sides. The foil tab has a plate-like portion that engages with the winding start side of the positive or negative electrode and a comb-like portion that protrudes from the positive or negative electrode. The comb-tooth section is the connecting part of the electrode winding body.

4. The secondary battery according to claim 3, wherein, The spacing of the strip-shaped protrusions in the comb teeth gradually increases from the side where the winding begins.

5. The secondary battery according to claim 3, wherein, The negative electrode also has a tab on the winding termination side.

6. The secondary battery according to claim 1, wherein, The positive electrode tab is located approximately one-third of the way from the start of the winding to the end of the winding. The positive electrode tab is located approximately one-third of the way from the end of the winding towards the beginning of the winding. The negative electrode tab is located approximately one-third of the way from the start of the winding of the negative electrode to the end of the winding. The positive and negative electrodes each have a flat foil tab on their respective winding start side. The foil tab has a plate-like portion that engages with the winding start side of the positive or negative electrode and a comb-like portion that protrudes from the positive or negative electrode. The comb-like portion serves as the connecting portion of the electrode winding body.

7. The secondary battery according to any one of claims 3 to 6, wherein, The material of the positive electrode foil tab and the material of the positive electrode foil tab are any one of aluminum, titanium, stainless steel (SUS) or composite materials thereof.

8. The secondary battery according to any one of claims 3 to 6, wherein, The foil tab 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.

9. The secondary battery according to any one of claims 3 to 6, wherein, The thickness of the positive electrode foil tab, or the thickness of the positive electrode foil tab, or the thickness of the negative electrode foil tab is 0.020 mm or more and 0.100 mm or less.

10. The secondary battery according to any one of claims 3 to 6, wherein, The number of turns of the foil tab of the positive electrode or the number of turns of the foil tab of the negative electrode is more than 1 turn and less than 2.5 turns.

11. The secondary battery according to any one of claims 1 to 3, wherein, The silicon dioxide content in the negative electrode active material layer is more than 5 wt% and less than 20 wt%.

12. An electronic device, A secondary battery having any one of claims 1 to 11.

13. A power tool, A secondary battery having any one of claims 1 to 12.

Images