JP2011171107A - Lithium ion battery and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique capable of enhancing reliability of a lithium ion battery. <P>SOLUTION: A bending part BED1 forcibly bendable when applied with a stress such as torsion is provided in a positive electrode current-collecting tab PTAB, and a position of the bending part BED1 is formed in an upper part of a separator SP1 (SP2) and a positive electrode ring PR. Further, the bending part BED1 provided in the positive electrode current-collecting tab PTAB is extendable. The current-collecting tab itself and the separator are restrained thereby from being damaged, and an active material is restrained thereby from being separated, even when the stress such as the torsion is applied onto the positive electrode current-collecting tab PTAB, to enhance the reliability of the lithium ion battery. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lithium ion battery and a manufacturing technique thereof, and in particular, to a lithium ion battery having a positive electrode plate coated with a positive electrode active material, a separator, and a negative electrode plate coated with a negative electrode active material, and a manufacturing technique thereof. And effective technology.

  Japanese Patent Application Laid-Open No. 2009-2224070 (Patent Document 1) was applied when forming an electrode winding body due to vibration and temperature change during use of a lithium ion battery, expansion / contraction of an active material accompanying charge / discharge, and the like. It describes a problem in which an unstable winding back occurs on the outer periphery of the electrode winding body due to the tension (tension), and thereby the current collecting tab is damaged. In patent document 1, in order to solve this subject, the current collection tab is provided with the width | variety detail. As a result, when the electrode winding body is rolled back, the width details of the current collecting tab are bent, whereby the tension can be relaxed.

  In JP 2009-187724 A (Patent Document 2), when the current collecting tab is twisted, the current collecting tab and the separator are rubbed to break the separator, resulting in a short circuit between the positive electrode and the negative electrode. Techniques for preventing this are described. Specifically, the friction between the current collecting tab and the separator is suppressed by setting the static friction coefficient of the separator to 0.6 or less.

JP 2009-2224070 A JP 2009-187724 A

  With the development of portable electronic devices, small secondary batteries that can be repeatedly charged are used as power supply sources for these portable electronic devices. Of these, lithium ion batteries are attracting attention because of their high energy density, long cycle life, low self-discharge characteristics, and high operating voltage. Lithium ion batteries have the advantages described above, and are therefore widely used in portable electronic devices such as digital cameras, notebook personal computers, and mobile phones. Furthermore, in recent years, research and development of large-sized lithium ion batteries capable of realizing high capacity, high output, and high energy density as batteries for electric vehicles and power storage batteries have been promoted. In particular, in the automobile industry, in order to cope with environmental problems, development of an electric vehicle that uses a motor as a power source and a hybrid vehicle that uses both an engine (internal combustion engine) and a motor as a power source are in progress. . Lithium ion batteries have attracted attention as power sources for such electric vehicles and hybrid vehicles.

  Lithium ion batteries include, for example, an electrode winding body in which a positive electrode plate coated with a positive electrode active material, a negative electrode plate coated with a negative electrode active material, and a separator that prevents contact between the positive electrode plate and the negative electrode plate are wound. I have. In the lithium ion battery, the electrode winding body is inserted into the outer can and the electrolyte is injected into the outer can. That is, in a lithium ion battery, a positive electrode plate coated with a positive electrode active material on a metal foil and a negative electrode plate coated with a negative electrode active material on a metal foil are formed in a band shape, and the positive electrode plate and the negative electrode plate formed in a band shape The electrode winding body is formed by winding in a spiral shape through the separator so that the electrode does not directly contact. When winding the positive electrode plate and the negative electrode plate, the positive electrode plate and the negative electrode plate are wound while applying tension (tension) in order to prevent twisting.

  Here, in a lithium ion battery that requires high input / output characteristics such as a power source for an electric vehicle, in order to reduce internal resistance, a large number of current collecting tabs are directly formed from metal foils constituting the positive electrode plate and the negative electrode plate. Has been derived. For example, in order to increase the output of the lithium ion battery, the positive electrode current collector tab is left without applying the positive electrode active material to a part of the metal foil that is the positive electrode plate, and the left region is divided into a plurality of regions. By processing into a rectangular shape, the positive electrode current collecting tab is derived directly from the positive electrode plate. Similarly, in order to increase the output of the lithium ion battery, the negative electrode current collecting tab is also left without applying the negative electrode active material to a part of the metal foil as the negative electrode plate, and a plurality of the remaining areas are provided. Thus, the negative electrode current collecting tab is directly derived from the negative electrode plate.

  The ends of the extracted positive electrode current collecting tab and negative electrode current collecting tab are connected to peripheral portions of disc-shaped positive electrode current collecting rings and negative electrode current collecting rings respectively arranged on both sides of the electrode winding body.

  In the lithium ion battery configured as described above, vibration and temperature change during use of the lithium ion battery, expansion and contraction of the active material accompanying charging / discharging, and the like occur. Therefore, the tension applied when forming the electrode winding body Due to (tension), an unstable winding back occurs on the outer periphery of the electrode winding body. If the above-mentioned unstable winding-back occurs in the electrode winding body, the current collecting tab connecting the electrode winding body and the current collecting ring may be twisted, and the current collecting tab itself may be damaged or the current collecting tab may be damaged. There is a risk that the tab may press the adjacent separator and cause damage to the separator. Furthermore, the active material may be peeled off from the positive electrode plate or the negative electrode plate from which the current collecting tab is led out. That is, when unstable winding back occurs in the electrode winding body, the current collecting tab is twisted and the like, resulting in a problem that the reliability of the lithium ion battery is lowered.

  In addition, as another configuration example of the lithium ion battery, there is a laminate type lithium ion battery in which a plurality of positive plates and a plurality of negative plates are stacked via a separator. Also in this laminate type lithium ion battery, a positive electrode current collecting tab is derived from each of the plurality of positive electrode plates, and the plurality of derived positive electrode current collecting tabs are collectively connected to the positive electrode current collecting ring. Similarly, a negative electrode current collecting tab is derived from each of the plurality of negative electrode plates, and the plurality of derived negative electrode current collecting tabs are collectively connected to the negative electrode current collecting ring. Therefore, even in a laminated lithium ion battery, vibration and temperature changes during use of the lithium ion battery, expansion and contraction of the active material accompanying charging / discharging, etc. occur, so the current collecting tab connected to the current collecting ring twists, etc. May occur, and the current collecting tab itself may be damaged or the separator adjacent to the current collecting tab may be damaged. Furthermore, the active material may be peeled off from the positive electrode plate or the negative electrode plate from which the current collecting tab is led out. As described above, in the wound type lithium ion battery and the laminated type lithium ion battery, since the current collecting tab is used, the reliability deterioration of the lithium ion battery due to the twisting of the current collecting tab becomes a problem. .

  An object of the present invention is to provide a technique capable of improving the reliability of a lithium ion battery.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  A lithium ion battery according to a typical embodiment includes (a) a positive electrode plate coated with a positive electrode active material containing a lithium-containing transition metal oxide, and (b) a negative electrode active material containing a material capable of inserting and releasing lithium ions. A negative electrode plate coated with a substance; (c) a separator provided between the positive electrode plate and the negative electrode plate; and (d) an electrolyte solution injected between the positive electrode plate and the negative electrode plate. And (e) a positive electrode current collecting tab formed on the positive electrode plate, (f) a positive electrode current collecting ring electrically connected to the positive electrode current collecting tab, and (g) a negative electrode formed on the negative electrode plate. A current collecting tab; and (h) a negative electrode current collecting ring electrically connected to the negative electrode current collecting tab. Here, the positive electrode current collecting tab is formed with a bendable and stretchable first bent portion, and the negative electrode current collecting tab is bendable and stretchable with a second bend. The part is formed. The first bent portion exists between one end portion of the separator and the positive electrode current collecting ring, and the second bent portion exists between the other end portion of the separator and the negative electrode current collecting ring. Is.

  Further, a method for manufacturing a lithium ion battery according to a typical embodiment includes (a) a step of forming a positive electrode plate coated with a positive electrode active material containing a lithium-containing transition metal oxide, and (b) the positive electrode plate. And forming a positive current collecting tab on the positive electrode plate, which is formed with a first bent portion that is bendable and stretchable by processing. (C) forming a negative electrode plate coated with a negative electrode active material containing a material capable of inserting and releasing lithium ions; and (d) processing the negative electrode plate to allow bending and expansion and contraction. Forming a negative electrode current collecting tab having a second bent portion having a property on the negative electrode plate. (E) preparing a separator; and (f) winding the positive electrode plate, the separator, and the negative electrode plate to form an electrode winding body, and forming the positive electrode from one side of the electrode winding body. And a step of projecting the current collecting tab and projecting the negative electrode current collecting tab from the other side of the electrode winding body. Subsequently, (g) a step of disposing a positive electrode current collecting ring on one side of the electrode winding body, and electrically connecting the positive electrode current collecting ring and the positive electrode current collecting tab; Disposing a negative electrode current collecting ring on the other side of the rotating body, and electrically connecting the negative electrode current collecting ring and the negative electrode current collecting tab. And (i) a step of inserting and fixing the electrode winding body into an outer can, (j) a step of injecting an electrolyte into the outer can, and (k) a step of sealing the outer can. Is provided. Here, the first bent portion exists between one end portion of the separator and the positive electrode current collecting ring, and the second bent portion exists between the other end portion of the separator and the negative electrode current collecting ring. To do.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  The reliability of the lithium ion battery can be improved.

It is a figure which shows the typical structure of a lithium ion battery. It is sectional drawing which shows the internal structure of a cylindrical lithium ion battery. It is a figure which shows the component of the previous step which comprises an electrode winding body. It is a schematic diagram which shows a mode that a positive electrode, a separator, and a negative electrode are wound and an electrode winding body is formed. (A) is a top view showing a state in which the electrode winding body has been wound back, and (b) is a diagram illustrating a case where the electrode winding body and the positive electrode current collector ring are twisted when the electrode winding body is twisted. It is sectional drawing which shows a mode that a twist generate | occur | produces in the positive electrode current collection tab which connects. It is a side view which shows the structure of the positive electrode of the lithium ion battery in Embodiment 1 of this invention. It is sectional drawing cut | disconnected by the AA line of FIG. FIG. 3 is a cross-sectional view showing a state where the electrode winding body and the positive electrode current collector ring are connected by the positive electrode current collector tab in the first embodiment. 6 is a diagram showing a modification in the first embodiment. FIG. 6 is a diagram showing a modification in the first embodiment. FIG. 6 is a diagram showing a modification in the first embodiment. FIG. FIG. 3 is a cross-sectional view showing a state in which an electrode winding body and a negative electrode current collecting ring are connected by a negative electrode current collecting tab in the first embodiment. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is sectional drawing cut | disconnected by the AA line of FIG. It is sectional drawing cut | disconnected by the AA line of FIG. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. It is a figure explaining the manufacturing process of the lithium ion battery in Embodiment 1 of this invention. 6 is a diagram showing a modification in the first embodiment. FIG. It is a figure which shows the typical structure of the laminate-type lithium ion battery which laminates | stacks and arrange | positions several positive electrode plates and several negative electrode plates through a separator as another structural example of a lithium ion battery. FIG. 10 is a schematic diagram illustrating a state in which a stacked positive electrode and a positive electrode current collector ring are connected by a positive electrode current collector tab according to a second embodiment.

  In the following embodiments, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, they are not irrelevant to each other. There are some or all of the modifications, details, supplementary explanations, and the like.

  Further, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except, it is not limited to the specific number, and may be more or less than the specific number.

  Further, in the following embodiments, the constituent elements (including element steps and the like) are not necessarily indispensable unless otherwise specified and apparently essential in principle. Needless to say.

  Similarly, in the following embodiments, when referring to the shape, positional relationship, etc., of components, etc., unless otherwise specified, and in principle, it is considered that this is not clearly the case, it is substantially the same. Including those that are approximate or similar to the shape. The same applies to the above numerical values and ranges.

  In all the drawings for explaining the embodiments, the same members are denoted by the same reference symbols in principle, and the repeated explanation thereof is omitted. In order to make the drawings easy to understand, even a plan view may be hatched.

(Embodiment 1)
Lithium has a redox potential of −3.03 V (vs. NHE), and is the most base metal present on the earth. Since the voltage of the battery is determined by the potential difference between the positive electrode and the negative electrode, the highest electromotive force can be obtained when lithium is used as the negative electrode active material. Further, since the atomic weight of lithium is 6.94 and the density is 0.534 g / cm ³ , both of which are small, the weight per unit amount of electricity is small and the energy density is also high. Therefore, when lithium is used for the negative electrode active material, a small and lightweight battery can be manufactured.

  As described above, lithium is an attractive material as a negative electrode active material of a battery, but problems arise when applied to a chargeable / dischargeable secondary battery. That is, when charging and discharging are repeated in a battery using lithium as a negative electrode, a discharge reaction due to dissolution of lithium and a charge reaction due to precipitation of lithium occur. In this case, repetitive charging causes a lithium precipitation reaction, which causes problems in the performance deterioration and safety of the secondary battery. For example, lithium generated in the charging process reacts with the electrolyte solvent on the active surface, and part of it is consumed for forming a film called SEI (Solid Electrolyte Interface). For this reason, the internal resistance of the battery increases and the discharge efficiency also decreases. In other words, the battery capacity decreases each time the charge / discharge cycle is repeated. Furthermore, when rapidly charged, lithium precipitates in a needle-like / dendritic crystal form (lithium dendrite), which causes various troubles in the secondary battery. For example, lithium dendrite has a large specific surface area, accelerates a decrease in current efficiency due to side reactions, and also has a needle shape, so it may break through the separator and cause an internal short circuit between the positive electrode and the negative electrode. In such a state, the self-discharge is so large that it cannot be used as a battery, or heat generation due to an internal short circuit may cause gas ejection or ignition. From the above, it can be seen that secondary batteries using lithium as the negative electrode have problems in performance degradation and safety.

  Therefore, a new type secondary battery having a principle different from the conventional principle of dissolution and precipitation has been studied. Specifically, a secondary battery using an active material that inserts and releases lithium ions into both the positive electrode and the negative electrode has been studied. In the charging / discharging process of the secondary battery, the phenomenon of dissolution and precipitation of lithium does not occur, and only lithium ions are inserted and desorbed between the electrode active materials. This type of secondary battery is called “rocking chair” type or “shuttle cock” type, and it is stable because lithium ions are only inserted and extracted with repeated charging and discharging. There is the feature that it is. This type of battery will be referred to herein as a lithium ion battery. As described above, in the lithium ion battery, the structure of both the positive electrode and the negative electrode does not change during charging and discharging, and only lithium ions are inserted and desorbed (however, the active material crystal lattice is lithium ion). In addition to the fact that it has an extremely long life cycle characteristic and does not use metallic lithium for the electrode, it has the characteristics that the safety is also dramatically improved.

  Here, a material capable of inserting / extracting lithium ions is used for the active material of the electrode. The conditions required for this active material are as follows. That is, since ions of a finite size called lithium ions are inserted and desorbed, a site (position) where lithium ions should be stored and a channel (path) through which lithium ions can be diffused are required for the active material. Furthermore, electrons need to be introduced into the active material as lithium ions are inserted (occluded).

  Examples of the positive electrode active material that satisfies the above conditions include lithium-containing transition metal oxides. Examples of typical positive electrode active materials include, but are not limited to, lithium cobaltate, lithium nickelate, and lithium manganate. Specifically, the positive electrode active material is a material capable of inserting / extracting lithium, and may be any lithium-containing transition metal oxide in which a sufficient amount of lithium has been previously inserted, and manganese (Mn) as a transition metal , Nickel (Ni), cobalt (Co), iron (Fe) or the like, or a material mainly composed of two or more transition metals. Further, the crystal structure such as the spinel crystal structure and the layered crystal structure is not particularly limited as long as the above-described sites and channels are ensured. Further, a material in which a part of the transition metal or lithium in the crystal is replaced with an element such as Fe, Co, Ni, Cr, Al, Mg, or an element such as Fe, Co, Ni, Cr, Al, Mg in the crystal A material doped with may be used as the positive electrode active material.

  Furthermore, a crystalline carbon material or an amorphous carbon material can be used as the negative electrode active material that satisfies the above-described conditions. However, the negative electrode active material is not limited to these materials. For example, natural graphite, various artificial graphite agents, coal-based coke, coal-based pitch carbide, petroleum-based coke, petroleum-based pitch carbide, pitch Carbon materials such as coke carbide may be used. And also in the particle shape, various particle shapes such as a scale shape, a spherical shape, a fiber shape, and a lump shape are applicable.

  Hereinafter, a schematic configuration of the above-described lithium ion battery will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a lithium ion battery. In FIG. 1, the lithium ion battery has an outer can CS, and the outer can CS is filled with an electrolyte EL. In the outer can CS filled with the electrolyte EL, the positive electrode plate PEP and the negative electrode plate NEP are provided to face each other, and the separator SP is provided between the positive electrode plate PEP and the negative electrode plate NEP provided to face each other. Has been placed.

  A positive electrode active material is applied to the positive electrode plate PEP, and a negative electrode active material is applied to the negative electrode plate NEP. For example, the positive electrode active material is formed of a lithium-containing transition metal oxide capable of inserting / extracting lithium ions. FIG. 1 schematically shows that the lithium-containing transition metal oxide is applied to the positive electrode plate PEP. That is, FIG. 1 shows a schematic crystal structure in which oxygen, metal atoms, and lithium are arranged as the lithium-containing transition metal oxide applied to the positive electrode plate PEP. This positive electrode plate PEP and the positive electrode active material constitute a positive electrode.

  On the other hand, for example, the negative electrode active material is formed of a carbon material capable of inserting and removing lithium ions. FIG. 1 schematically shows a state in which this carbon material is applied to the negative electrode plate NEP. That is, FIG. 1 shows a schematic crystal structure in which carbon is arranged as the carbon material applied to the negative electrode plate NEP. The negative electrode is composed of the negative electrode plate NEP and the negative electrode active material.

  The separator SP has a function as a spacer that allows lithium ions to pass through while preventing electrical contact between the positive electrode and the negative electrode. In recent years, a high-strength and thin microporous film has been used as the separator SP. This microporous membrane also has a function of preventing abnormal current due to a short circuit of the battery, rapid increase in internal pressure and temperature, and ignition. In other words, the current separator SP has a function as a thermal fuse for preventing a short circuit and overcharge in addition to a function of preventing electrical contact between the positive electrode and the negative electrode and allowing lithium ions to pass therethrough. become. The safety of the lithium ion battery can be maintained by the shutdown function of the microporous membrane. For example, when a lithium ion battery causes an external short circuit for some reason, there is a risk that a large current flows instantaneously but the temperature rises abnormally due to Joule heat. At this time, if a microporous membrane is used as the separator SP, the microporous membrane closes the pores (microporous) in the vicinity of the melting point of the membrane material, so that lithium ions can permeate between the positive electrode and the negative electrode. Can be blocked. In other words, by using a microporous membrane as the separator SP, it is possible to cut off the current when the external short circuit occurs and stop the temperature rise inside the lithium ion battery. As separator SP comprised from this microporous membrane, it can comprise from polyethylene (PE), polypropylene (PP), or the combination of these materials, for example.

A non-aqueous electrolyte is used as the electrolyte EL. The lithium ion battery is a battery that performs charging / discharging by using insertion / extraction of lithium ions in an active material, and lithium ions move in the electrolyte EL. Lithium is a strong reducing agent and reacts violently with water to generate hydrogen gas. Therefore, in a lithium ion battery in which lithium ions move in the electrolytic solution EL, an aqueous solution cannot be used as the electrolytic solution EL unlike a conventional battery. For this reason, in the lithium ion battery EL, a non-aqueous electrolyte is used as the electrolyte EL. Specifically, as _the electrolyte of the non-aqueous electrolyte _{EL, LiPF 6, LiClO 4,} LiAsF 6, LiBF 4, LiB (C 6 H 5) 4, CH 3 SO 3 Li, CF 3 SO 3 Li , etc. and these Mixtures can be used. Examples of the organic solvent include ethylene carbonate, dimethyl carbonate, propylene carbonate, diethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl- 1,3 dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, etc., or a mixture thereof can be used.

  The lithium ion battery is configured as described above, and the charging / discharging mechanism will be described below. First, the charging mechanism will be described. As shown in FIG. 1, when charging a lithium ion battery, a charger CU is connected between the positive electrode and the negative electrode. In this case, in the lithium ion battery, lithium ions inserted in the positive electrode active material are desorbed and released into the electrolyte EL. At this time, the lithium ions are desorbed from the positive electrode active material, whereby electrons flow from the positive electrode to the charger. The lithium ions released into the electrolytic solution EL move through the electrolytic solution EL, pass through the separator SP made of a microporous film, and reach the negative electrode. The lithium ions that have reached the negative electrode are inserted into the negative electrode active material constituting the negative electrode. At this time, when lithium ions are inserted into the negative electrode active material, electrons flow into the negative electrode. In this way, charging is completed as electrons move from the positive electrode to the negative electrode via the charger.

  Next, the discharge mechanism will be described. As shown in FIG. 1, an external load is connected between the positive electrode and the negative electrode. Then, lithium ions inserted in the negative electrode active material are desorbed and released into the electrolyte EL. At this time, electrons are emitted from the negative electrode. The lithium ions released into the electrolytic solution EL move through the electrolytic solution EL, pass through the separator SP made of a microporous film, and reach the positive electrode. The lithium ions reaching the positive electrode are inserted into the positive electrode active material constituting the positive electrode. At this time, when lithium ions are inserted into the positive electrode active material, electrons flow into the positive electrode. In this way, discharge is performed by the movement of electrons from the negative electrode to the positive electrode. In other words, a current can flow from the positive electrode to the negative electrode to drive the load. As described above, in a lithium ion battery, charging / discharging can be performed by inserting / extracting lithium ions between the positive electrode active material and the negative electrode active material.

  Next, a configuration example of an actual lithium ion battery LIB will be described. FIG. 2 is a cross-sectional view showing the internal structure of a cylindrical lithium ion battery LIB. As shown in FIG. 2, an electrode winding body WRF including a positive electrode PEL, separators SP1 and SP2, and a negative electrode NEL is formed inside a cylindrical outer can CS having a bottom. Specifically, the electrode winding body WRF is stacked so as to sandwich the separator SP1 (SP2) between the positive electrode PEL and the negative electrode NEL, and is wound around the axis CR in the center of the outer can CS. . The negative electrode NEL is electrically connected to the negative electrode lead plate NT provided at the bottom of the outer can CS, and the positive electrode PEL is electrically connected to the positive electrode lead plate PT provided at the upper portion of the outer can CS. Has been. An electrolyte is injected into the electrode winding body formed inside the outer can CS. The outer can CS is sealed with a battery lid CAP.

  The positive electrode PEL is formed by applying a coating liquid containing a positive electrode active material PAS and a binder (binder) to a positive electrode plate (positive electrode current collector) PEP, drying it, and then pressurizing it. A plurality of rectangular positive electrode current collecting tabs PTAB are formed on the upper end portion of the positive electrode PEL, and the plurality of positive electrode current collecting tabs PTAB are welded to the positive electrode current collecting ring PR. The positive electrode current collection ring PR is electrically connected to the positive electrode lead plate PT. Therefore, the positive electrode PEL is electrically connected to the positive electrode lead plate PT via the positive electrode current collecting tab PTAB and the positive electrode current collecting ring PR. The plurality of positive electrode current collecting tabs PTAB are provided in order to reduce the resistance of the positive electrode PEL and to quickly extract current.

  As the positive electrode active material PAS constituting the positive electrode PEL, for example, the above-described materials represented by lithium cobaltate, lithium nickelate, lithium manganate and the like can be used. As the binder, for example, polyvinyl fluoride, polyvinylidene fluoride, polytetrafluoroethylene, or the like can be used. Furthermore, for the positive electrode plate, for example, a metal foil or a net-like metal made of a conductive metal such as aluminum is used.

  The negative electrode NEL is formed by applying a coating liquid containing the negative electrode active material NAS and a binder (binder) to the negative electrode plate (negative electrode current collector) NEP and drying it, followed by pressurization. A plurality of rectangular negative electrode current collecting tabs NTAB are formed at the lower end of the negative electrode NEL, and the plurality of negative electrode current collecting tabs NTAB are welded to the negative electrode current collecting ring NR. And this negative electrode current collection ring NR is electrically connected with the negative electrode lead board NT. Therefore, the negative electrode NEL is electrically connected to the negative electrode lead plate NT via the negative electrode current collecting tab NTAB and the negative electrode current collecting ring NR.

  As the negative electrode active material NAS constituting the negative electrode NEL, for example, the above-described materials typified by a carbon material can be used. As the binder, for example, polyvinylidene fluoride, polytetrafluoroethylene, or the like can be used. Furthermore, for the negative electrode plate, for example, a metal foil made of a conductive metal such as copper or a mesh metal is used.

  In addition, the binder (binder) used for the positive electrode PEL and the negative electrode NEL includes polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene / butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethyl cellulose, Various latexes, polymers such as acrylonitrile, vinyl fluoride, propylene fluoride, chloroprene fluoride, and mixtures thereof can be used.

  Next, a detailed configuration of the electrode winding body will be described. FIG. 3 is a diagram showing components in a previous stage constituting the electrode winding body. In FIG. 3, the components constituting the electrode winding body in the first embodiment are a positive electrode PEL, a separator SP1, a negative electrode NEL, and a separator SP2. At this time, the positive electrode PEL has a structure in which the positive electrode active material PAS is applied to both surfaces of the positive electrode plate PEP, and the negative electrode NEL has a structure in which the negative electrode active material NAS is applied to both surfaces of the negative electrode plate NEP. . A plurality of rectangular positive electrode current collecting tabs PTAB are formed on the upper side of the positive electrode PEL. Similarly, a plurality of rectangular negative electrode current collecting tabs NTAB are formed on the lower side of the negative electrode NEL.

  FIG. 4 is a schematic diagram showing how the electrode wound body WRF is formed by winding the positive electrode PEL, the separator SP1, the negative electrode NEL, and the separator SP2. As shown in FIG. 4, the positive electrode PEL, the separator SP1, the negative electrode NEL, and the separator SP2 are wound so that the separator SP1 is sandwiched between the positive electrode PEL and the negative electrode NEL and the negative electrode NEL is sandwiched between the separator SP1 and the separator SP2. Is done. At this time, the positive electrode current collecting tab PTAB formed on the positive electrode PEL is disposed on the upper side of the electrode winding body WRF, while the negative electrode current collecting tab NTAB formed on the negative electrode NEL is disposed on the lower side of the electrode winding body WRF. Placed on the side.

  In the lithium ion battery configured as described above, vibration and temperature change during use of the lithium ion battery, expansion and contraction of the active material accompanying charging / discharging, and the like occur. Therefore, it was applied when forming the electrode winding body WRF. The tension (tension) causes unstable winding back at the outer periphery of the electrode winding body WRF. When the unstable winding back described above occurs in the electrode winding body WRF, the current collecting tab connecting the electrode winding body WRF and the current collecting ring is twisted, and the current collecting tab itself is damaged, There is a possibility that the current collecting tab may press the adjacent separator and cause damage to the separator. Furthermore, the active material may be peeled off from the positive electrode plate or the negative electrode plate from which the current collecting tab is led out. That is, when unstable winding back occurs in the electrode winding body WRF, the current collecting tab is twisted and the like, resulting in a problem that the reliability of the lithium ion battery is lowered.

  Specifically, this problem will be described with reference to the drawings. FIG. 5A is a top view showing a state in which the electrode winding body WRF has been wound back. As shown in FIG. 5 (a), the positive electrode current collector ring PR is disposed on the upper part of the electrode winding body WRF, and the positive electrode current collector ring PR and the positive electrode current collector tab derived from the electrode winding body WRF. PTAB is connected. Here, as shown in FIG. 5 (a), consider a case in which the electrode winding body WRF is twisted clockwise. In this case, the positive electrode current collecting tab PTAB is also twisted due to the twist applied to the electrode winding body WRF.

  FIG. 5B is a cross-sectional view showing a state in which twisting occurs in the positive electrode current collecting tab PTAB that connects the electrode winding body WRF and the positive electrode current collecting ring PR when twisting occurs in the electrode winding body WRF. It is. In FIG.5 (b), the electrode winding body WRF has the structure which wound positive electrode PEL, separator SP1, negative electrode NEL, and separator SP2. A positive electrode current collecting tab PTAB is led out from the positive electrode PEL, and the positive electrode current collecting tab PTAB is connected to the positive electrode current collecting ring PR. At this time, the positive electrode PEL has a structure in which the positive electrode active material PAS is applied to both surfaces of the positive electrode plate PEP, and the negative electrode NEL has a structure in which the negative electrode active material NAS is applied to both surfaces of the negative electrode plate NEP. .

  Here, as shown in FIG. 5B, when the positive electrode current collecting tab PTAB is twisted, the positive electrode current collecting tab PTAB comes into contact with the separators SP1 and SP2 and presses the separators SP1 and SP2. At this time, when the positive electrode current collector tab PTAB contacts with the separators SP1 and SP2, the positive electrode current collector tab PTAB may be rubbed and cut. Further, the separators SP1 and SP2 may be bent due to pressure from the positive electrode current collecting tab PTAB. Moreover, when the separators SP1 and SP2 are deformed, the negative electrode NEL sandwiched between the separators SP1 and SP2 is also deformed. Due to this deformation, the negative electrode active material NAS may be peeled off from the negative electrode plate NEP constituting the negative electrode NEL. As described above, when an unstable winding back occurs in the electrode winding body WRF, the positive electrode current collecting tab PTAB is twisted, and as a result, there is a problem that the reliability of the lithium ion battery is lowered. Recognize. In addition, although the twist of positive electrode current collection tab PTAB is demonstrated, the same problem arises also in negative electrode current collection tab NTAB.

  Therefore, in the first embodiment, even when the current collecting tab is twisted, the reliability of the lithium ion battery is suppressed by suppressing damage to the current collecting tab itself, damage to the separator, and peeling of the active material. The device is improved. Hereinafter, the technical idea of the first embodiment to which this device has been applied will be described with reference to the drawings.

  FIG. 6 is a side view showing the structure of positive electrode PEL of the lithium ion battery according to the first embodiment. As shown in FIG. 6, the positive electrode PEL has a structure in which a positive electrode active material PAS is applied to a positive electrode plate PEP. An uncoated region where the positive electrode active material PAS is not applied exists at the end of the positive electrode plate PEP. A plurality of positive electrode current collecting tabs PTAB are led upward from the uncoated region. The positive electrode current collecting tab PTAB has a rectangular shape and is integrally formed with the positive electrode plate PEP. Here, the feature of the first embodiment is that a bent portion BND1 is formed in a part of the positive electrode current collecting tab PTAB.

  Hereinafter, the shape of the bent portion BND1 will be described with reference to FIG. 7 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 7, a linear positive electrode current collecting tab PTAB is formed integrally with the positive electrode plate PEP coated with the positive electrode active material PAS on both sides, and a part of the positive electrode current collecting tab PTAB is formed. A bent portion BND1 is formed. The bent portion BND1 has, for example, a W shape. Accordingly, the bent portion BND1 becomes a base point where the positive electrode current collecting tab PTAB is bent and also has a stretchable portion. By providing the W-shaped bent portion BND1 on the linear positive electrode current collecting tab PTAB in this way, even if stress such as twist is applied to the positive electrode current collecting tab PTAB, the current collecting tab itself is damaged. Further, it is possible to improve the reliability of the lithium ion battery by suppressing the breakage of the separator and the peeling of the active material.

  FIG. 8 is a cross-sectional view showing a state in which the electrode winding body WRF and the positive electrode current collector ring PR are connected by the positive electrode current collector tab PTAB in the first embodiment. As shown in FIG. 8, the bent portion BND1 is formed in the positive electrode current collecting tab PTAB in the first embodiment. In the first embodiment, the bent part BND1 is arranged between the separator SP1 (SP2) and the positive electrode current collecting ring PR. That is, the bent portion BND1 is provided at a position higher than the height of the upper end portion of the separator SP1 (SP2) and lower than the positive electrode current collecting ring PR. Thereby, the positive electrode current collection tab PTAB derived from the positive electrode PEL does not contact the separator SP1 (SP2), extends in the vertical direction (up and down direction in FIG. 8), and is higher than the upper end of the separator SP1 (SP2). The bent portion BND1 provided at the position is bent. For this reason, even when stress such as torsion is applied to the positive electrode current collector tab PTAB, the positive electrode current collector tab PTAB is bent at the bent portion BND1, so that the positive electrode current collector tab PTAB is separated from the separator. Contact with SP1 (SP2) can be suppressed.

  That is, when the bent portion BND1 is not provided in the positive electrode current collecting tab PTAB, when a stress such as twist is applied, the positive electrode current collecting tab PTAB is easily deformed so as to be bent from the base. In this case, the positive electrode current collecting tab PTAB and the separator SP1 (SP2) are in contact with each other. Then, the cathode current collecting tab PTAB and the separator SP1 (SP2) are rubbed together, the cathode current collecting tab PTAB itself is damaged, or the separator SP1 (SP2) is pressed against the cathode current collecting tab PTAB itself. Cause damage.

  On the other hand, in the first embodiment, since the bent portion BND1 is provided in the positive electrode current collecting tab PTAB, the positive electrode current collecting tab PTAB is bent from the root even when stress such as torsion is applied. It is difficult to bend, and it is forcibly bent at the bent portion BND1 which is easy to bend. The positive electrode current collecting tab PTAB led out from the positive electrode PEL is brought into contact with the separator SP1 (SP2) by placing the bent portion BND1 between the separator SP1 (SP2) and the positive electrode current collecting ring PR. Instead, it is bent at a bent portion BND1 that extends in the vertical direction (vertical direction in FIG. 8) and is higher than the upper end of the separator SP1 (SP2). This is because even when stress such as torsion is applied to the positive electrode current collector tab PTAB, the positive electrode current collector tab PTAB is forcibly bent at the bent portion BND1 provided on the upper part of the separator SP1 (SP2). Therefore, it means that the positive electrode current collecting tab PTAB can suppress bending below the bent part BND1. As a result, it is possible to prevent the positive electrode current collecting tab PTAB and the separator SP1 (SP2) from rubbing. That is, according to the first embodiment, even when a stress such as twist is applied to the positive electrode current collector tab PTAB, the positive electrode current collector tab PTAB and the separator SP1 (SP2) come into contact with each other and press against each other. The reliability of the lithium ion battery can be improved by suppressing the damage of the positive electrode current collecting tab PTAB itself, the damage of the separator SP1 (SP2) itself, and the peeling of the active material.

  As described above, the first characteristic point of the first embodiment is that the bending portion BND1 that is easily bent when a stress such as torsion is applied is provided in the positive electrode current collecting tab PTAB, and the position of the bending portion BND1 is determined. It is to be formed between the upper end portion of the separator SP1 (SP2) and the positive electrode current collecting ring PR. Thereby, the positive electrode current collecting tab PTAB is hardly bent from the base, and the contact between the positive electrode current collecting tab PTAB and the separator SP1 (SP2) can be suppressed. That is, according to the technical idea of the first embodiment, the bending position of the positive electrode current collector tab PTAB is controlled by the bent portion BND1, and the formation position of the bent portion BND1 is adjusted to twist the positive electrode current collector tab PTAB. Even when this stress is applied, the contact between the positive electrode current collector tab PTAB and the separator SP1 (SP2) can be prevented. As an example for realizing this technical idea, in the first embodiment, the bent portion BND1 is formed in a W shape.

  By configuring the bent portion BND1 from the W shape in this manner, the bent portion BND1 is easily bent and the second feature point in the first embodiment becomes obvious. That is, when the bent portion BND1 is formed in a W shape, the bent portion BND1 also has elasticity such as a spring. For example, consider a case where tension is generated in the positive electrode current collecting tab PTAB due to stress such as twisting. In this case, in a normal positive electrode current collector tab PTAB having no stretchability, the generated tension is applied to the positive electrode current collector tab PTAB as it is, so that the positive electrode current collector tab PTAB is deformed or cut by this tension. It tends to occur.

  On the other hand, in the first embodiment, the bent portion BND1 is also stretchable by making the bent portion BND1 W-shaped. Thereby, even when tension is generated in the positive electrode current collecting tab PTAB due to stress such as torsion, the tension applied to the positive electrode current collecting tab PTAB is relaxed by expansion / contraction of the bending portion BND1 having elasticity. Can do it. As a result, for example, by providing the bent portion BND1 having a W shape on the positive electrode current collecting tab PTAB, the positive electrode current collecting tab PTAB is hardly cut.

  As described above, in the first embodiment, when a stress such as torsion is applied, a bent portion BND1 that is easily bent is provided in the positive electrode current collecting tab PTAB, and the position of the bent portion BND1 is set to the separator SP1 ( The first characteristic point is that it is formed between the upper end of SP2) and the positive electrode current collecting ring PR. Furthermore, the second characteristic point is that the bent portion BND1 provided on the positive electrode current collecting tab PTAB has elasticity.

  As a configuration example of the bent portion BND1 having the first feature point and the second feature point as described above, in the first embodiment, an example in which the bent portion BND1 is formed in a W shape is given. However, the configuration of the bent portion BND including the first feature point and the second feature point is not limited to this. For example, FIG. 9 is a diagram illustrating a modification example of the first embodiment. As shown in FIG. 9, by providing the positive electrode current collecting tab PTAB with a V-shaped bent portion BND2, the bent portion BND2 serves as a bending base point (first characteristic point), and the bent portion BND2 is stretchable. (Second feature point).

  FIG. 10 is a diagram illustrating a modification of the first embodiment. As shown in FIG. 10, the bent portion BND3 is also a base point for bending by providing the positive electrode current collecting tab PTAB with a bent portion BND3 having a combination of a V shape and a W shape (first feature point). At the same time, the bent portion BND3 has elasticity (second feature point).

  Further, FIG. 11 is a diagram illustrating a modification example of the first embodiment. As shown in FIG. 11, by providing the positive electrode current collecting tab PTAB with a plurality of bent portions BND1 having a W shape, the plurality of bent portions BND1 serve as the bending base points (first characteristic points), and a plurality of bent portions BND1 are provided. The bent portion BND1 has elasticity (second feature point).

  In the first embodiment, the example in which the bent portion BND1 is provided on the positive electrode current collecting tab PTAB has been described. However, as shown in FIG. 12, the negative electrode current collector connecting the electrode winding body WRF and the negative electrode current collecting ring NR. You may comprise so that bending part BND1 may be provided in electric tab NTAB.

  FIG. 12 is a cross-sectional view showing a state where the electrode winding body WRF and the negative electrode current collector ring NR are connected by the negative electrode current collector tab NTAB in the first embodiment. As shown in FIG. 12, a bent portion BND1 is formed on the negative electrode current collecting tab NTAB in the first embodiment. In the first embodiment, the bent portion BND1 is located between the separator SP1 (SP2) and the negative electrode current collecting ring NR. That is, the bent portion BND1 is provided at a position lower than the height of the lower end portion of the separator SP1 (SP2) and higher than the negative electrode current collecting ring NR. Thereby, the negative electrode current collection tab NTAB led out from the negative electrode NEL does not contact the separator SP1 (SP2), extends in the vertical direction (up and down direction in FIG. 12), and is lower than the lower end portion of the separator SP1 (SP2). The bent portion BND1 provided at the position is bent. For this reason, even when stress such as torsion is applied to the negative electrode current collector tab NTAB, the negative electrode current collector tab NTAB is bent at the bent portion BND1, so that the negative electrode current collector tab NTAB is separated from the separator. Contact with SP1 (SP2) can be suppressed.

  Furthermore, by making the bent part BND1 W-shaped, the bent part BND1 also has stretchability. This means that even if tension is generated in the negative electrode current collector tab NTAB due to stress such as torsion, the tension applied to the negative electrode current collector tab NTAB is relieved by the expansion and contraction of the bending portion BND1 having elasticity. It can be done. As a result, for example, by providing the negative electrode current collector tab NTAB with the bent portion BND1 having a W shape, the negative electrode current collector tab NTAB is less likely to be cut.

  The lithium ion battery in the first embodiment is configured as described above, and the manufacturing method thereof will be described below with reference to the drawings.

First, as shown in FIG. 13, a positive electrode active material PAS (active material AS) is manufactured. As the positive electrode active material PAS, lithium manganese cobalt nickel composite oxide (LiMn _1/3 Ni _1/3 Co _1/3 O ₂ ), which is a transition metal composite oxide, can be used. In addition, carbon black and graphite can be used as a conductive aid, and polyvinylidene fluoride (PVDF) can be used as a binder. Next, as shown in FIG. 14, N-methylpyrrolidone (NMP) was used as a solvent, and the solid weight after drying the paste was positive electrode active material PAS: conducting aid: binder = 85: 11: 4. The coating liquid (positive electrode material paste) SL is adjusted by weighing the mixture so as to satisfy the following ratio and kneading with a solvent. After that, as shown in FIG. 15, a coating liquid SL containing a positive electrode active material PAS, a conductive additive, and a binder is applied to a positive electrode plate (positive electrode current collector) PEP and dried, and then a pressure roller Press (press). Thereby, it is possible to increase the density of the positive electrode active material PAS applied to the positive electrode plate PEP. An uncoated region of the coating liquid SL is formed on one side along the longitudinal direction of the positive electrode plate PEP.

  Similarly, as shown in FIG. 13, the negative electrode active material NAS (active material AS) is manufactured. As the negative electrode active material NAS, pseudo-anisotropic carbon of amorphous carbon can be used. In addition, carbon black can be used as a conductive aid, and polyvinylidene fluoride (PVDF) can be used as a binder. Next, as shown in FIG. 14, N-methylpyrrolidone (NMP) was used as a solvent, and the solid weight after drying the paste was negative electrode active material NAS: conducting aid: binder = 88: 5: 7 The coating liquid (negative electrode material paste) SL is adjusted by weighing the mixture so as to satisfy the following ratio and kneading with a solvent. Thereafter, as shown in FIG. 15, a coating liquid SL containing a negative electrode active material NAS, a conductive additive, and a binder is applied to a negative electrode plate (negative electrode current collector) NEP and dried, and then a pressure roller Press (press). Thereby, it is possible to increase the density of the negative electrode active material NAS applied to the negative electrode plate NEP. An uncoated region of the coating liquid SL is formed on one side along the longitudinal direction of the negative electrode plate NEP.

  Subsequently, as shown in FIG. 16, the uncoated region of the positive electrode plate PEP coated with the positive electrode active material PAS is cut into a strip shape (comb shape) by a press cutter or the like. Thereby, a plurality of positive electrode current collecting tabs PTAB having a rectangular shape on one side (upper side) of the positive electrode plate PEP can be formed. Further, a bent portion BND1 is formed by press-molding a part of the formed positive electrode current collecting tab PTAB. Thus, the positive electrode PEL processed by applying the positive electrode active material PAS to the positive electrode plate PEP can be formed.

  Similarly, as shown in FIG. 17, an uncoated region of the negative electrode plate NEP coated with the negative electrode active material NAS is cut into a strip shape (comb shape) by a press cutter or the like. Accordingly, a plurality of negative electrode current collecting tabs NTAB having a rectangular shape on one side (lower side) of the negative electrode plate NEP can be formed. Further, the bent portion BND1 is formed by press-molding a part of the formed negative electrode current collecting tab NTAB. Thus, the negative electrode NEL processed by applying the negative electrode active material NAS to the negative electrode plate NEP can be formed.

  Here, FIG. 18 is a cross-sectional view taken along line AA of FIG. As shown in FIG. 18, the positive electrode current collecting tab PTAB is led out from the positive electrode PEL made of the positive electrode plate PEP and the positive electrode active material PAS, and a W-shaped bent portion BND1 is formed in a part of the positive electrode current collecting tab PTAB. You can see that Similarly, FIG. 19 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 19, the negative electrode current collecting tab NTAB is led out from the negative electrode NEL made of the negative electrode plate NEP and the negative electrode active material NAS, and a W-shaped bent portion BND1 is formed in a part of the negative electrode current collecting tab NTAB. You can see that These bent portions BND1 are bendable and have elasticity.

  Thereafter, as shown in FIGS. 20 and 21, a rectangular separator SP1 and a rectangular separator SP2 are prepared. As described above, the positive electrode PEL, the negative electrode NEL, the separator SP1, and the separator SP2 can be prepared.

  Next, as shown in FIG. 22, the positive electrode PEL, the negative electrode NEL, the separator SP1, and the separator SP2 are placed so that the negative electrode NEL is sandwiched between the separator SP2 and the separator SP1 and the positive electrode PEL is disposed on the separator SP1. Laminate. At this time, the positive electrode current collecting tab PTAB formed in the positive electrode PEL and the negative electrode current collecting tab NTAB formed in the negative electrode NEL are arranged in opposite directions.

  Thereafter, as shown in FIG. 23, the laminated positive electrode PEL, negative electrode NEL, separator SP1 and separator SP2 are wound on a hollow cylindrical shaft core (not shown) made of polypropylene to form an electrode winding body WRF.

  Subsequently, as shown in FIG. 24, a current collection ring PR is disposed on the upper side of the electrode winding body WRF, and the positive electrode current collection tab PTAB protruding from the upper end of the electrode winding body WRF is focused to collect the positive electrode current collection. Connect to the peripheral edge of the electric ring PR. Similarly, a current collecting ring NR is arranged on the lower side of the electrode winding body WRF, and the negative electrode current collecting tab NTAB protruding from the lower end portion of the electrode winding body WRF is focused on the peripheral edge portion of the negative electrode current collecting ring NR. Connecting. Here, the connection of the positive electrode current collecting tab PTAB to the positive electrode current collecting ring PR and the connection of the negative electrode current collecting tab NTAB to the negative electrode current collecting ring NR are performed by, for example, ultrasonic welding.

  By this process, the bent portion BND1 formed on the positive electrode current collecting tab PTAB exists between one end of the separator and the positive electrode current collecting ring PR, and the bent portion BND1 formed on the negative electrode current collecting tab NTAB is It exists between the other end part of a separator and the negative electrode current collection ring NR.

  Next, as shown in FIG. 25, after the electrode winding body WRF is inserted into the outer can CS, the negative electrode current collecting ring PR is resistance-welded to the bottom of the outer can CS. Then, as shown in FIG. 26, the outer can CS is processed to form the grooves DT. The groove DT is provided to fix the electrode winding body WRF inserted in the outer can CS so as not to move in the vertical direction.

And as shown in FIG. 27, electrolyte solution EL is inject | poured into the exterior can CS which inserted the electrode winding body WRF. Specifically, for example, 1 mol / liter of lithium hexafluorophosphate (LiPF ₆ ) is dissolved as a lithium salt in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC). Solution was injected. Thereafter, one end of a positive electrode lead plate in which an aluminum foil is laminated in a ribbon shape is welded to the positive electrode current collecting ring PR, and the other end of the positive electrode lead plate is welded to the bottom surface of a cap for sealing the outer can CS. Then, the cap is fixed by caulking the outer can CS through an electrically insulating gasket between the peripheral edge of the cap and the outer can CS. In this way, the lithium ion battery in the first embodiment can be manufactured.

  In the first embodiment, the lithium ion battery in which the electrode winding body WRF has a cylindrical shape has been described. However, the technical idea of the present invention is, for example, as shown in FIG. The present invention can also be applied to a lithium ion battery in which WRF has a square shape.

(Embodiment 2)
In the first embodiment, the example in which the present invention is applied to a wound lithium ion battery has been described. In the second embodiment, the present invention is applied to a stacked (laminated) lithium ion battery. Will be described.

  FIG. 29 is a diagram showing a schematic configuration of a laminate-type lithium ion battery LIB in which a plurality of positive plates and a plurality of negative plates are stacked via a separator, as another configuration example of the lithium ion battery. As shown in FIG. 29, also in this laminated lithium ion battery LIB, the positive electrode current collecting tab PTAB is derived from each of the plurality of positive electrode plates, and the plurality of derived positive electrode current collecting tabs PTAB are collectively collected into the positive electrode current collector. Connected to a ring (not shown). Similarly, the negative electrode current collecting tab NTAB is derived from each of the plurality of negative electrode plates, and the plurality of derived negative electrode current collecting tabs NTAB are collectively connected to a negative electrode current collecting ring (not shown). Therefore, even in the laminate type lithium ion battery LIB, vibration and temperature change during use of the lithium ion battery and expansion / shrinkage of the active material accompanying charging / discharging occur. Therefore, the current collecting tab connected to the current collecting ring There is a risk that twisting or the like may occur, causing damage to the current collecting tab itself, or causing pressure on the separator adjacent to the current collecting tab to cause damage to the separator. Furthermore, the active material may be peeled off from the positive electrode plate or the negative electrode plate from which the current collecting tab is led out. That is, in the laminated lithium ion battery LIB, since the current collecting tab is used, there is a problem that the reliability of the lithium ion battery is lowered due to the twisting of the current collecting tab.

  Therefore, also in the second embodiment, a bent portion is provided on the current collecting tab. FIG. 30 is a schematic diagram showing a state in which the positive electrode PEL and the positive electrode current collector ring PR that are stacked are connected by the positive electrode current collector tab PTAB in the second embodiment. As shown in FIG. 30, the positive electrode current collecting tab PTAB in the second embodiment has a bent portion BND1. In the second embodiment, the bent portion BND1 is located between the separator SP and the positive electrode current collecting ring PR. Thereby, the positive electrode current collecting tab PTAB led out from the positive electrode PEL extends in the horizontal direction (left and right direction in FIG. 30) without contacting the separator SP, and is provided at a position on the right side of the right end portion of the separator SP. It will be bent at the bent portion BND1. For this reason, even when stress such as torsion is applied to the positive electrode current collector tab PTAB, the positive electrode current collector tab PTAB is bent at the bent portion BND1, so that the positive electrode current collector tab PTAB is separated from the separator. Contact with SP can be suppressed.

  Furthermore, by making the bent part BND1 W-shaped, the bent part BND1 also has stretchability. This means that even if tension is generated in the positive electrode current collecting tab PTAB due to stress such as torsion, the tension applied to the positive electrode current collecting tab PTAB is relaxed by the expansion and contraction of the bending portion BND1 having elasticity. It can be done. As a result, for example, by providing the bent portion BND1 having a W shape on the positive electrode current collecting tab PTAB, the positive electrode current collecting tab PTAB is hardly cut.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  The present invention can be widely used in the manufacturing industry for manufacturing lithium ion batteries.

AS active material BND1 bent part BND2 bent part BND3 bent part CAP battery cover CR shaft core CS outer can CU charger DT groove EL electrolyte LIB lithium ion battery NAS negative electrode active material NEL negative electrode NEP negative electrode plate NR negative electrode current collecting ring NT Plate NTAB Negative electrode current collecting tab PAS Positive electrode active material PEL Positive electrode PEP Positive electrode plate PR Positive electrode current collecting ring PT Positive electrode lead plate PTAB Positive electrode current collecting tab SL Coating liquid SP Separator SP1 Separator SP2 Separator WRF Electrode winding body

Claims (12)

(A) a positive electrode plate coated with a positive electrode active material containing a lithium-containing transition metal oxide;
(B) a negative electrode plate coated with a negative electrode active material containing a material capable of inserting and releasing lithium ions;
(C) a separator provided between the positive electrode plate and the negative electrode plate;
(D) an electrolyte solution injected between the positive electrode plate and the negative electrode plate;
(E) a positive electrode current collecting tab formed on the positive electrode plate;
(F) a positive electrode current collector ring electrically connected to the positive electrode current collector tab;
(G) a negative electrode current collecting tab formed on the negative electrode plate;
(H) a lithium ion battery comprising a negative electrode current collector ring electrically connected to the negative electrode current collector tab,
The positive electrode current collecting tab is formed with a first bent portion that is bendable and has elasticity,
The negative electrode current collecting tab is formed with a second bent portion that is bendable and has elasticity.
The first bent portion exists between one end of the separator and the positive electrode current collecting ring,
The lithium ion battery, wherein the second bent portion exists between the other end of the separator and the negative electrode current collecting ring. The lithium ion battery according to claim 1,
The first bent portion is formed by processing a part of the positive electrode current collecting tab into a V shape, a W shape, or a combined shape of the V shape and the W shape. A featured lithium-ion battery. The lithium ion battery according to claim 1,
The lithium ion battery is characterized in that there are a plurality of the first bent portions. The lithium ion battery according to claim 1,
The second bent portion is formed by processing a part of the negative electrode current collecting tab into a V shape, a W shape, or a combined shape of the V shape and the W shape. A featured lithium-ion battery. The lithium ion battery according to claim 1,
The lithium ion battery according to claim 1, wherein a plurality of the second bent portions are present. The lithium ion battery according to claim 1,
The lithium ion battery, wherein the positive electrode plate, the separator, and the negative electrode plate are wound to form an electrode winding body. The lithium ion battery according to claim 1,
The positive electrode plate, the separator, and the negative electrode plate are laminated to form a laminated structure. (A) forming a positive electrode plate coated with a positive electrode active material containing a lithium-containing transition metal oxide;
(B) forming a positive current collecting tab on the positive electrode plate by forming the first bent portion that is bendable and stretchable by processing the positive electrode plate;
(C) forming a negative electrode plate coated with a negative electrode active material containing a material capable of inserting and releasing lithium ions;
(D) forming a negative electrode current collecting tab on the negative electrode plate, which is formed by forming the second bent portion that is bendable and stretchable by processing the negative electrode plate;
(E) preparing a separator;
(F) winding the positive electrode plate, the separator, and the negative electrode plate to form an electrode winding body, projecting the positive electrode current collecting tab from one side of the electrode winding body, and the electrode winding Projecting the negative electrode current collecting tab from the other side of the body;
(G) disposing a positive electrode current collector ring on one side of the electrode winding body, and electrically connecting the positive electrode current collector ring and the positive electrode current collector tab;
(H) disposing a negative electrode current collector ring on the other side of the electrode winding body, and electrically connecting the negative electrode current collector ring and the negative electrode current collector tab;
(I) inserting and fixing the electrode winding body in an outer can;
(J) injecting an electrolyte into the outer can;
(K) a step of sealing the outer can,
The first bent portion exists between one end of the separator and the positive electrode current collecting ring,
The method of manufacturing a lithium ion battery, wherein the second bent portion exists between the other end of the separator and the negative electrode current collecting ring. A method of manufacturing a lithium ion battery according to claim 8,
In the step (b), a part of the positive electrode current collecting tab is processed into a V shape, a W shape, or a combination shape of the V shape and the W shape, thereby obtaining the positive current collector tab. The first bent portion is formed on the lithium ion battery. A method of manufacturing a lithium ion battery according to claim 8,
A manufacturing method of a lithium ion battery, wherein a plurality of the first bent portions exist. A method of manufacturing a lithium ion battery according to claim 8,
In the step (d), a part of the negative electrode current collecting tab is processed into a V shape, a W shape, or a combination shape of the V shape and the W shape, thereby obtaining the negative electrode current collecting tab. Forming the second bent portion in a method of manufacturing a lithium ion battery. A method of manufacturing a lithium ion battery according to claim 8,
A method of manufacturing a lithium ion battery, wherein a plurality of the second bent portions exist.

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