JP2008311011A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery which can secure a suitable current route even though areas of a positive electrode and a negative electrode are excessively large and is suitable for an application such as an on-vehicle power source or a backup power source by reducing DC resistance. <P>SOLUTION: In the nonaqueous electrolyte secondary battery, a group of electrodes for making the positive electrodes and the negative electrodes laminated or wound so as to face each other via separators, wherein each layer including an active material is arranged on an approximately rectangular current collector, and a nonaqueous electrolyte are stored in an external wrapping body with a positive electrode terminal and a negative electrode terminal. Exposure sections for exposing current collectors are arranged along two parallel sides of the positive electrode and the negative electrode, both the exposure sections on the positive electrode are electrically connected with a positive electrode current collection member through the outside of the group of electrodes, and both the exposure sections on the negative electrode are electrically connected with a negative electrode current collection member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

 The present invention relates to a non-aqueous electrolyte secondary battery that is relatively large and has high input / output characteristics.

 Nonaqueous electrolyte secondary batteries (mainly lithium ion secondary batteries) with high voltage and high energy density are used as main power sources for mobile devices such as mobile communication devices and portable electronic devices. In recent years, in-vehicle power supplies, backup power supplies, and large-scale devices are becoming DC-driven in light of environmental problems, and it is demanded to increase the size and output of lithium-ion secondary batteries that can be reduced in weight. .

  A lithium ion secondary battery is formed by laminating a positive electrode and a negative electrode provided with a layer containing an active material on a current collector with a separator interposed therebetween, in a substantially rectangular shape, or in a cylindrical or substantially rectangular shape. The electrode group is formed by winding into a shape, and this is manufactured by housing it in a package body including a battery case and a lid together with a nonaqueous electrolyte. Here, when an electrode group formed by laminating in a substantially rectangular shape is configured, a positive electrode and a negative electrode having substantially the same shape as the electrode group are used. Further, when forming an electrode group wound in a cylindrical or substantially rectangular shape, a belt-like positive electrode and negative electrode are used.

  In the lithium ion secondary battery having the above-described structure, when the amount of the active material per unit area in the positive electrode and the negative electrode is randomly increased (the layer containing the active material is thickened), the input / output characteristics are remarkably deteriorated. In order to obtain a lithium ion secondary battery with good input / output characteristics, the amount of active material per unit area in the positive electrode and the negative electrode is reduced compared to the case of a lithium ion secondary battery used as the main power source of a mobile device. (It is necessary to make the layer containing the active material thin).

In addition, in order to improve the input / output characteristics of the lithium ion secondary battery, it is necessary to make the current paths of the positive electrode and the negative electrode efficient. For example, when an electrode group in which a belt-like positive electrode and negative electrode are wound is adopted, a current collector is exposed by exposing the current collector at one end of the positive electrode and the negative electrode, like a lithium ion secondary battery used as a main power source of a mobile device When joining the lead (such as a lead) and making an electrical connection with the positive electrode terminal and the negative electrode terminal, one end of the belt-like positive electrode and the negative electrode is greatly separated from the current collecting member (the current path becomes longer). It becomes large and sufficient input / output characteristics cannot be obtained. Therefore, the current collector of the positive electrode or the negative electrode is exposed in the longitudinal direction and protrudes from one end of the electrode group, and the exposed current collector is plane-pressed along the cylindrical axis direction and bent inward to flatten the flat portion. Forming and welding a current collector plate to the flat part (see Patent Document 1), or a positive or negative current collector provided in the longitudinal direction with a number of leads and protruding from one end of the electrode group, A technique for collecting leads (see Patent Document 2) has been proposed.
JP 2000-294222 A Japanese Patent Laid-Open No. 09-092335

 However, in the case of an application that requires a large capacity and high input / output characteristics, such as an in-vehicle power supply and a backup power supply, it is necessary to excessively increase the areas of the positive electrode and the negative electrode. It was not enough. The present invention was devised in view of the above-mentioned problems of the prior art, and even if the areas of the positive electrode and the negative electrode become excessively large, an appropriate current path is ensured and the DC resistance is reduced to reduce the on-board power supply or backup power supply. It is providing the nonaqueous electrolyte secondary battery suitable for uses, such as.

  In order to solve the above-described conventional problems, the nonaqueous electrolyte secondary battery of the present invention is such that a positive electrode and a negative electrode provided with a layer containing an active material on a substantially rectangular current collector face each other through a separator. A group of electrodes laminated or wound together and a non-aqueous electrolyte are housed in an exterior body having a positive electrode terminal and a negative electrode terminal, and a current collector is formed along two parallel sides of the positive electrode and the negative electrode. An exposed exposed portion is provided, and both of the exposed portions of the positive electrode are electrically connected to the positive current collector through the outside of the electrode group, and both of the exposed portions of the negative electrode are electrically connected to the negative current collector. It is characterized by that.

  Providing current collectors along two parallel sides of the positive and negative electrodes, and joining current collectors to each of them ensures an appropriate current path even when the area of the positive and negative electrodes becomes excessively large Since the direct current resistance can be reduced, a non-aqueous electrolyte secondary battery having a large capacity and high input / output characteristics can be obtained.

  According to the present invention, it is possible to obtain a nonaqueous electrolyte secondary battery having a large capacity and high input / output characteristics.

 The best mode for carrying out the present invention will be described below with reference to the drawings.

  According to a first aspect of the present invention, there is provided an electrode group in which a positive electrode and a negative electrode provided with a layer containing an active material on a substantially rectangular current collector are stacked or wound so as to face each other through a separator, a non-aqueous electrolyte, Is provided in an exterior body having a positive electrode terminal and a negative electrode terminal, provided with an exposed portion where the current collector is exposed along two parallel sides of the positive electrode and the negative electrode, and through the outside of the electrode group, The present invention relates to a non-aqueous electrolyte secondary battery in which both exposed portions of a positive electrode are electrically connected to a positive electrode current collector and both exposed portions of a negative electrode are electrically connected to a negative electrode current collector.

(Embodiment 1)
FIG. 1 is a plan view of a positive electrode and a negative electrode used in forming a wound electrode group in the nonaqueous electrolyte secondary battery of the present invention. Each of the positive electrode 11 and the negative electrode 12 is formed by providing a layer containing an active material on a strip-shaped current collector. These lengths and widths can be arbitrarily set according to the desired battery capacity. A plurality of strip-shaped exposed portions 13 and 14 are provided along two longitudinal sides of the positive electrode 11 and the negative electrode 12. 1 shows a form in which a plurality of exposed portions 13 and 14 protrude from the positive electrode 11 and the negative electrode 12, but a form in which a metal lead is joined and protruded instead of the above-described exposed portion protruding, or Needless to say, a configuration in which one exposed exposed portion (or lead) is also within the scope of the present invention.

 FIG. 2 is a schematic view of a wound electrode group in a nonaqueous electrolyte battery configured using the positive electrode and the negative electrode of FIG. A belt-like positive electrode 11 and a negative electrode 12 are wound through a separator (not shown), and both exposed portions 13 of the positive electrode 11 are bundled and electrically connected by a connecting member 15, and then a tongue-like protrusion. Is electrically connected to the positive electrode current collecting member 17 provided with. On the other hand, both the exposed portions 14 of the negative electrode 12 are bundled and electrically connected by the connecting member 15, and then electrically connected to the negative electrode current collecting member 18 provided with a tongue-shaped protrusion. This electrode group is inserted into a battery case (not shown), and the tongue-shaped protrusion of the negative electrode current collecting member 18 is electrically connected to the bottom of the battery case. Subsequently, the tongue-like protrusion of the positive electrode current collecting member 17 is electrically connected to a lid (not shown). Here, the connecting members 15 and 16 are arranged so as not to contact each other. Furthermore, the nonaqueous electrolyte is injected into the battery case, and a lid is placed on the opening of the battery case to seal it, thereby forming the nonaqueous electrolyte secondary battery of the present invention.

(Embodiment 2)
FIG. 3 is a plan view of a positive electrode and a negative electrode used in forming a wound electrode group in the nonaqueous electrolyte secondary battery of the present invention. Each of the positive electrode 21 and the negative electrode 22 is formed by providing a layer containing an active material on a strip-shaped current collector. These lengths and widths can be arbitrarily set according to the desired battery capacity. Exposed portions 23 and 24 are provided along two sides in the longitudinal direction of the positive electrode 21 and the negative electrode 22. Here, one of the exposed portions 23 and 24 of the positive electrode 21 and the negative electrode 22 has a plurality of strip shapes, and the other has a continuous strip shape. 3 shows a form in which a plurality of strip-like exposed portions 23 and 24 protrude from the positive electrode 21 and the negative electrode 22, but instead of the above-described exposed portions protruding, metal leads are joined and protruded. Needless to say, a form or a form having one exposed exposed portion (or lead) is also within the scope of the present invention.

 FIG. 4 is a schematic view of a wound electrode group in a nonaqueous electrolyte battery configured using the positive electrode and the negative electrode of FIG. The belt-like positive electrode 21 and the negative electrode 22 are wound through a separator (not shown). Here, the plurality of strip-shaped ones of the exposed portions 23 of the positive electrode 21 and the plurality of strip-shaped ones of the exposed portions 24 of the negative electrode 22 are arranged on either one of the upper and lower surfaces of the electrode group. To. Further, a plurality of strip-shaped ones of the exposed portions 23 of the positive electrode 21 are bundled through the through holes 28a provided in the negative electrode current collecting member 28, and electrically connected by the other exposed portions 23 and the connecting members 25, It is electrically connected to the positive electrode current collecting member 27 provided with a tongue-like protrusion. On the other hand, a plurality of strip-shaped ones of the exposed portions 24 of the negative electrode 22 are bundled through the through holes 27 a provided in the positive current collecting member 27 and electrically connected by the other exposed portions 24 and the connecting members 26. , And electrically connected to the negative electrode current collector 28 provided with tongue-like protrusions. This electrode group is inserted into a battery case (not shown), and the tongue-shaped protrusion of the negative electrode current collector 28 is electrically connected to the bottom of the battery case. Subsequently, the tongue-shaped protrusion of the positive electrode current collecting member 27 is electrically connected to a lid (not shown). Here, the connecting members 25 and 26 are arranged so as not to contact each other. Furthermore, the nonaqueous electrolyte is injected into the battery case, and a lid is placed on the opening of the battery case to seal it, thereby forming the nonaqueous electrolyte secondary battery of the present invention.

  Needless to say, when the exposed portion 23 of the positive electrode 21 is bundled through the through hole 28a provided in the negative electrode current collecting member 28, it is necessary to provide an insulating material at a predetermined location to prevent a short circuit.

  Needless to say, when the exposed portion 24 of the negative electrode 22 is bundled through the through hole 27a provided in the positive electrode current collecting member 27, it is necessary to provide an insulating material at a predetermined location to prevent a short circuit.

  By adopting the second embodiment, there is an advantage that the positive electrode 21 and the negative electrode 22 can be easily processed and the resistance can be reduced by increasing the number of collecting points as compared with the case of employing the first embodiment.

(Embodiment 3)
FIG. 5 is a plan view of a positive electrode and a negative electrode used in forming a wound electrode group in the nonaqueous electrolyte secondary battery of the present invention. Each of the positive electrode 31 and the negative electrode 32 is formed by providing a layer containing an active material on a strip-shaped current collector. These lengths and widths can be arbitrarily set according to the desired battery capacity. A plurality of strip-shaped exposed portions 33 and 34 are provided along two longitudinal sides of the positive electrode 31 and the negative electrode 32. The exposed portions 13 and 14 gradually increase in width from the wound core when the electrode group is formed toward the outside. 1 shows a form in which a plurality of exposed portions 13 and 14 protrude from the positive electrode 11 and the negative electrode 12, but a form in which a metal lead is joined and protruded instead of the above-described exposed portion protruding, or Needless to say, a configuration in which one exposed exposed portion (or lead) is also within the scope of the present invention.

6 to 9 are schematic views of a wound electrode group in a nonaqueous electrolyte battery configured using the positive electrode and the negative electrode of FIG. The belt-like positive electrode 31 and the negative electrode 32 are wound through a separator (not shown), and the exposed portion 33 of the positive electrode 31 and the exposed portion 34 of the negative electrode 32 face each other on the upper and lower surfaces of the electrode group. Protrusively in a semicircular shape.

  The exposed portions 33 of both positive electrodes 31 are electrically connected to a substantially semicircular positive electrode current collecting member 37 and further electrically connected by a connecting member 35, and the exposed portions 34 of both negative electrodes 32 are substantially semi-circulated. A positive electrode in an exterior body composed of a battery case (not shown) and a lid (not shown) is electrically connected to the circular negative electrode current collecting member 38 and further connected to the circular negative electrode current collecting member 38. Depending on the position where the terminal and the negative electrode terminal are provided, the location where the tongue-shaped protrusion connected to these terminals is provided differs. For example, when both the positive electrode terminal and the negative electrode terminal are provided on the upper surface (or lower surface) of the outer package, the tongue-shaped protrusion is as shown in FIG. In addition, when the positive electrode terminal and the negative electrode terminal are provided on the upper surface and the lower surface of the exterior body, respectively, the tongue-shaped protrusion is as shown in FIG. Further, in the case where both the positive electrode terminal and the negative electrode terminal are provided on the side surface of the outer package, the tongue-shaped protrusion is as shown in FIG.

  Next, this electrode group is inserted into the battery case, and the positive electrode current collecting member 37 and the positive electrode terminal are electrically connected through a tongue-shaped protrusion, and the negative electrode current collecting member 38 and the negative electrode terminal are also connected through a tongue-shaped protrusion. And electrically connect. Furthermore, the nonaqueous electrolyte is injected into the battery case, and a lid is placed on the opening of the battery case to seal it, thereby forming the nonaqueous electrolyte secondary battery of the present invention. The advantage of the third embodiment is that it can be adapted to various types of exterior bodies simply by changing the position where the tongue-like protrusion is provided.

  According to a second invention, in the first invention, the exposed portions of the positive electrode and the negative electrode are laminated so as to be arranged on different sides of the electrode group, respectively.

(Embodiment 4)
10 to 15 are a cross-sectional view and a plan view of a positive electrode used in forming a stacked electrode group in the nonaqueous electrolyte secondary battery of the present invention. Needless to say, the negative electrode takes the same form.

 The positive electrode 41 is formed by providing a layer containing an active material on a substantially rectangular current collector. However, an exposed portion 42 of the current collector is provided along two parallel sides of the positive electrode 41. Yes. Note that the exposed portion 42 may be provided continuously along two parallel sides of the positive electrode 41 as shown in FIG. 11, or may be provided singly on two parallel sides of the positive electrode 41 as shown in FIG. A plurality of electrodes may be provided on two parallel sides of the positive electrode 41 as shown in FIG. Furthermore, it goes without saying that the forms of FIGS. 14 and 6 in which one or a plurality of metallic leads 42a are projected in place of the above-described exposed portion 42 not projecting are also within the scope of the present invention.

 A plurality of the exposed portions 42 of the positive electrode 41 and the exposed portions 44 of the negative electrode 43 having the same configuration are stacked via the separator 45 so as to be in a substantially perpendicular direction to each other as shown in FIG. Thereafter, as shown in FIG. 17 which is a cross-sectional view taken along the line aa in FIG. 16, both exposed portions 42 of the positive electrode 41 are electrically connected to the positive electrode current collecting member 46, and are further connected by the connecting member 47. As shown in FIG. 18 which is a cross-sectional view taken along line bb of FIG. 16, both the exposed portions 44 of the negative electrode 43 are electrically connected to the negative electrode current collector 48 and further connected. Electrical connection is made by member 49. This electrode group is inserted into a battery case (not shown), and the positive current collecting member 46 and the negative current collecting member 48 are electrically connected to the positive terminal and the negative terminal, respectively. Subsequently, a non-aqueous electrolyte is injected into the battery case, and a lid (not shown) is installed at the opening of the battery case to seal it, thereby forming the non-aqueous electrolyte secondary battery of the present invention.

  The nonaqueous electrolyte secondary battery of the present invention will be further described in detail.

For the connection between the exposed portion, the lead, the positive current collecting member, the negative current collecting member, the connecting member, the tongue-like protrusion, the positive terminal and the negative terminal, ultrasonic bonding, resistance welding, laser welding, etc. The method can be taken. These members related to current collection can cover an appropriate portion with an insulating material as necessary in order to prevent a short circuit.

  For the lead connected to the exposed portion of the positive electrode, for example, a strip-shaped metal piece made of a conductive metal such as stainless steel, aluminum, or titanium can be used. For the lead connected to the exposed portion of the negative electrode, for example, a strip-shaped metal piece made of a conductive metal such as stainless steel, nickel, or copper can be used. The thickness of these leads is not particularly limited, but is preferably 0.01 to 0.30 mm. By setting the thickness of the lead within the above range, the weight can be reduced while suppressing heat generation during charging and discharging. Further, a plurality of leads may be used as needed, or a plurality of leads may be added.

  The positive electrode is prepared by mixing a positive electrode mixture composed of an active material and an optional component with a liquid component to prepare a positive electrode mixture slurry, applying the obtained slurry to a current collector, drying, and then, if necessary, predetermined After being rolled to a thickness, it is cut into a predetermined dimension.

  The negative electrode is prepared by mixing a negative electrode mixture composed of an active material and an optional component with a liquid component to prepare a negative electrode mixture slurry, applying the obtained slurry to a current collector, drying, and then, if necessary, predetermined After being rolled to a thickness, it is cut into a predetermined dimension.

  As the positive and negative electrode current collectors, a long porous conductive substrate or a nonporous conductive substrate is used. As a material used for the conductive substrate, stainless steel, aluminum, titanium, or the like is used in the case of the positive electrode, and stainless steel, nickel, copper, or the like is used in the case of the negative electrode. Although the thickness of these electrical power collectors is not specifically limited, 1-500 micrometers is preferable and 5-20 micrometers is more desirable. By setting the thickness of the current collector within the above range, it is possible to reduce the weight while maintaining the strength of the positive electrode and the negative electrode.

A lithium composite metal oxide can be used for the active material of the positive electrode of the present invention. For _{example, Li x CoO 2, Li x} NiO 2, Li x MnO 2, Li x Co y Ni 1-y O 2, Li x Co y M 1-y O z, Li x Ni 1-y M y O z, _{Li x Mn 2 O 4, Li} x Mn 2-y M y O 4, LiMePO4, Li 2 MePO 4 F (M = Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, And at least one of Cr, Pb, Sb, and B). Here, x = 0 to 1.2, y = 0 to 0.9, and z = 2.0 to 2.3.

  Examples of the active material for the negative electrode of the present invention include metals, metal fibers, carbon materials, oxides, nitrides, tin compounds, silicon compounds, and various alloy materials. Examples of the carbon material include carbon materials such as various natural graphites, cokes, graphitized carbon, carbon fibers, spherical carbon, various artificial graphites, and amorphous carbon. In addition, a simple substance such as silicon (Si) or tin (Sn), or a silicon compound or tin compound such as an alloy, a compound, or a solid solution is preferable from the viewpoint of a large capacity density.

  For the positive or negative electrode binder of the present invention, for example, at least one selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethylene, polypropylene, aramid resin, and the like can be used.

 Examples of the conductive agent added to the positive electrode or the negative electrode include natural graphite and artificial graphite graphite, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and other carbon blacks, carbon fibers and metals. Conductive fibers such as fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide and potassium titanate, conductive metal oxides such as titanium oxide, and organic conductive materials such as phenylene derivatives Etc. can be used.

 The proportion of the solid content in the positive electrode mixture slurry is desirably 80 to 97% by weight of the active material, 1 to 20% by weight of the conductive agent, and 1 to 10% by weight of the binder. Moreover, it is desirable that the ratio of the solid content in the negative electrode mixture slurry is 93 to 99% by weight of the active material and 1 to 10% by weight of the binder.

 The exposed part is a method of preventing the positive electrode mixture slurry (or negative electrode mixture slurry) from being applied or filled in a part of the current collector, or the positive electrode mixture (or negative electrode mixture) at a predetermined position after application or filling. The method of peeling and removing is mentioned. In the case of the latter method, it is preferable to peel off and remove the positive electrode mixture (or negative electrode mixture) before rolling.

 As the separator, a microporous thin film, a woven fabric, a non-woven fabric, or the like having high ion permeability, predetermined mechanical strength, and insulation can be used. The separator material is preferably selected from polyolefins such as polypropylene and polyethylene. Since polyolefin is excellent in durability and has a shutdown function, the safety of the nonaqueous electrolyte secondary battery can be improved. The thickness of the separator is generally 10 to 300 μm, preferably 40 μm or less, more preferably 15 to 30 μm, even more preferably 10 to 25 μm. This separator may be a single layer film made of one material, or a composite film or a multilayer film made of one or more materials. The separator preferably has a porosity of 30 to 70%. Here, the porosity indicates the volume ratio of the pores to the separator volume. A more preferable range of the porosity of the separator is 35 to 60%.

  As the non-aqueous electrolyte, a liquid, gel, or solid (polymer solid electrolyte) substance can be used.

  As a material of the exterior body that houses the electrode group, a metal mainly composed of aluminum, iron, stainless steel, magnesium, or the like, or a laminate in which a resin is coated on the surface of a metal foil can be used.

(Example)
90 parts by weight of powder of active material Li _0.95 CoO ₂ mixed with Li ₂ CO ₃ and Co ₃ O ₄ and calcined at 900 ° C. for 10 hours, 2.5 parts by weight of acetylene black as a conductive agent, and binder A positive electrode mixture slurry was obtained by suspending in a PTFE dispersion. This slurry was applied to both surfaces of a 0.015 mm thick aluminum foil as a current collector. Here, the slurry was not applied to both ends of the current collector 10 mm each. The slurry was dried and then rolled to a thickness of 0.1 mm. Subsequently, a substantially rectangular positive electrode having 520 mm (of which 10 mm at both ends are exposed portions of the current collector) and the other side of 500 mm was produced.

  A 1% by weight styrene-butadiene rubber emulsion is added as a solid content to an active material (hereinafter referred to as mesophase graphite) obtained by graphitizing mesophase spherules at a high temperature of 2800 ° C. It was made to suspend and the negative mix slurry was obtained. This slurry was applied to both sides of a copper foil having a thickness of 0.008 mm as a current collector. Here, the slurry was not applied to both ends of the current collector 10 mm each. The slurry was dried and then rolled and cut to a thickness of 0.1 mm to produce a substantially rectangular negative electrode having one side of 522 mm (of which 10 mm at both ends are exposed portions of the current collector) and the other side of 502 mm. .

These eight positive electrodes and nine negative electrodes were laminated so that the exposed portions protruded in directions substantially perpendicular to each other through a polyethylene separator as shown in Embodiment 4 (FIGS. 16 to 18). Next, both exposed portions of the positive electrode were bundled and electrically connected to aluminum leads each having a thickness of 0.3 mm, a width of 5 mm, and a length of 10 mm by laser welding. On the other hand, both exposed portions of the negative electrode were bundled and electrically connected to copper leads having a thickness of 0.2 mm, a width of 5 mm, and a length of 10 mm, respectively, by resistance welding.

  Next, the two leads arranged at both ends of the positive electrode were electrically connected using an aluminum connecting member having a thickness of 0.3 mm and a width of 2 mm. On the other hand, the two leads arranged at both ends of the negative electrode were electrically connected using a copper connecting member having a thickness of 0.2 mm and a width of 2 mm.

After connecting the positive electrode connecting member to the aluminum positive electrode terminal and connecting the negative electrode connecting member to the copper negative electrode terminal, the positive electrode connecting member was inserted into a laminate case (a surface of the aluminum foil coated with polypropylene), and an electrolyte solution ( As nonaqueous electrolyte), a solution prepared by dissolving LiPF ₆ (1.40 mol / dm ³ ) in a solvent in which EC, EMC, and DMC were mixed at a volume ratio of 10:10:80 was injected, and the opening was heated. An example battery was made.

(Comparative example)
A comparative battery was fabricated in the same manner as in the example except that the exposed portion was formed only on one side of the positive electrode and the negative electrode.

  When the impedance at 1 KHz was measured using the battery of the example and the battery of the comparative example obtained as described above, the example was 2 mΩ and the comparative example was 4 mΩ.

  These batteries were charged at a constant current of 7.5 A until reaching 4.2 V, and then charged at a constant voltage of 4.2 V until the current was attenuated to 750 mA. Further, discharging was performed at a constant current of 7.5 A up to 2.0 V (first cycle). Subsequently, the same charging as in the first cycle was performed, and then discharging was performed at a constant current of 150 A to 2.0 V (second cycle). As a result of evaluating the ratio of the discharge capacity of the second cycle to the discharge capacity of the first cycle as an index of output characteristics, the example was 80% and the comparative example was 70%.

  Since the battery of the example of the present invention collects current from both ends of the positive electrode and the negative electrode, the impedance is reduced and the output characteristics are superior to the battery of the comparative example.

  Since the input / output characteristics of the nonaqueous electrolyte secondary battery are improved by the present invention, the industrial applicability is increased and the utility value is great.

Plan views of a positive electrode and a negative electrode used in the nonaqueous electrolyte secondary battery of Embodiment 1 of the present invention Schematic of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 1 of the present invention Plan views of a positive electrode and a negative electrode used in the nonaqueous electrolyte secondary battery according to Embodiment 2 of the present invention. Schematic of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 2 of the present invention Plan views of a positive electrode and a negative electrode used for the nonaqueous electrolyte secondary battery according to Embodiment 3 of the present invention. Schematic of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 3 of the present invention Schematic of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 3 of the present invention Schematic of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 3 of the present invention Schematic of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 3 of the present invention Sectional drawing of the positive electrode used for the nonaqueous electrolyte secondary battery of Embodiment 4 of this invention Plan view of the positive electrode used for the nonaqueous electrolyte secondary battery of Embodiment 4 of the present invention Plan view of the positive electrode used for the nonaqueous electrolyte secondary battery of Embodiment 4 of the present invention Plan view of the positive electrode used for the nonaqueous electrolyte secondary battery of Embodiment 4 of the present invention Plan view of the positive electrode used for the nonaqueous electrolyte secondary battery of Embodiment 4 of the present invention Plan view of the positive electrode used for the nonaqueous electrolyte secondary battery of Embodiment 4 of the present invention Schematic of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 4 of the present invention Sectional drawing of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 4 of this invention Sectional drawing of the electrode group used for the nonaqueous electrolyte secondary battery of Embodiment 4 of this invention

Explanation of symbols

11, 21, 31, 41 Positive electrode 12, 22, 32, 43 Negative electrode 13, 14, 23, 24, 33, 34, 42, 44 Exposed portion 15, 16, 25, 26, 35, 36, 47, 49 Connecting member 17, 18, 27, 28, 37, 38, 46, 48 Current collecting member 27a, 28a Through hole 42a Lead 45 Separator

Claims (2)

An electrode group in which a positive electrode and a negative electrode provided with a layer containing an active material on a substantially rectangular current collector are stacked or wound so that the negative electrode and the negative electrode face each other with a separator interposed therebetween, and a nonaqueous electrolyte, a positive electrode terminal and a negative electrode A non-aqueous electrolyte secondary battery housed in an exterior body having terminals,
An exposed portion formed by exposing the current collector is provided along two parallel sides of the positive electrode and the negative electrode,
Through the outside of the electrode group, both of the exposed portions of the positive electrode are electrically connected to a positive current collector, and both of the exposed portions of the negative electrode are electrically connected to a negative current collector. A non-aqueous electrolyte secondary battery. The nonaqueous electrolyte secondary battery according to claim 1, wherein the exposed portions of the positive electrode and the negative electrode are stacked so as to be disposed on different sides of the electrode group.

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