WO2018173701A1

WO2018173701A1 - Secondary battery manufacturing method and manufacturing device

Info

Publication number: WO2018173701A1
Application number: PCT/JP2018/008094
Authority: WO
Inventors: 和也石濱; 徹川合
Original assignee: 株式会社村田製作所
Priority date: 2017-03-21
Filing date: 2018-03-02
Publication date: 2018-09-27

Abstract

A secondary battery manufacturing method and manufacturing device are provided which, in the case that an electrode assembly precursor has a stepped portion, can apply a voltage not only to the topmost step of the electrode assembly precursor, but also to steps other than the topmost step. This invention relates to a secondary battery manufacturing method and manufacturing device in which a positive electrode and a negative electrode are arranged in an alternating fashion with a separator interposed therebetween, and an electrode assembly precursor 1 having a stepped portion 10 is pressed using a pressing member 3 having a pressing surface 3a corresponding to the stepped shape of the stepped portion 10, to obtain an electrode assembly.

Description

Secondary battery manufacturing method and manufacturing apparatus

The present invention relates to a method and an apparatus for manufacturing a secondary battery.

Conventionally, secondary batteries have been used as power sources for various electronic devices. The secondary battery has a structure in which an electrode assembly including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, and an electrolyte are enclosed in an exterior body. In particular, in a lithium ion secondary battery, lithium ions move between the positive electrode and the negative electrode through the electrolyte, and the battery is charged and discharged.

In manufacturing a secondary battery, an electrode assembly precursor in which positive electrodes and negative electrodes are alternately arranged via separators is pressed with a press plate to adhere and integrate the electrode assembly precursor. Get a solid. The electrode assembly is accommodated in the exterior body, and an electrolyte is injected into the exterior body to seal the inside of the exterior body.

On the other hand, electronic devices are becoming thinner and smaller, and accordingly, demand for thinner and smaller secondary batteries is increasing. A secondary battery provided with a stepped portion has been reported as a secondary battery that meets such requirements (Patent Documents 1 and 2).

International Publication No. 2015/141920 Japanese Patent No. 5779828

Accordingly, the inventors of the present invention have developed an electrode assembly precursor (for example, FIG. 9) having a stepped portion (for example, a stepped portion 305 having two upper surfaces having different heights as shown in FIG. 9). It has been found that even if the electrode assembly precursor 300 shown) is pressed with a press plate (eg,

press plates

310, 320 shown in FIG. 9), sufficient adhesion and integration of the electrode assembly precursor cannot be achieved. Specifically, as shown in FIG. 9, the press surface 311 of the press plate 310 has a planar shape and contacts only the upper surface of the uppermost step portion 301, so that the electrodes and the

step portions

302 and 303 other than the uppermost step portion 301 are arranged. It was difficult to fully integrate the separator and the like. As a result, the process of accommodating the obtained electrode assembly in the exterior body becomes complicated. Further, since the pressure applied to the electrode assembly precursor is non-uniform, the battery characteristics of the secondary battery are also non-uniform.

When the electrode assembly precursor has a stepped portion, the present invention can apply a pressure not only to the uppermost step portion of the electrode assembly precursor but also to a step portion other than the uppermost step portion. An object of the present invention is to provide a battery manufacturing method and a manufacturing apparatus.

Particularly, the present invention has an object to provide a method and an apparatus for manufacturing a secondary battery that can uniformly apply pressure to all the steps when the electrode assembly precursor has steps.

The present invention
A positive electrode and a negative electrode are alternately arranged via separators, and an electrode assembly precursor having a stepped portion is pressed using a pressing member having a press surface corresponding to the stepped shape of the stepped portion, to thereby form an electrode The present invention relates to a method for manufacturing a secondary battery (particularly a method for manufacturing an electrode assembly) to obtain an assembly.

The present invention also provides
A pressing member for alternately pressing a positive electrode and a negative electrode through separators and pressing an electrode assembly precursor having a stepped portion to obtain an electrode assembly, corresponding to the stepped shape of the stepped portion The present invention relates to a secondary battery manufacturing apparatus (particularly an electrode assembly manufacturing apparatus) including a pressed member having a pressed surface.

According to the method and apparatus for manufacturing a secondary battery of the present invention, even when the electrode assembly precursor has a stepped portion, not only the uppermost step portion of the electrode assembly precursor but also the uppermost step portion. The pressure can also be applied at the step. In particular, the pressure can be uniformly applied to all the steps. For this reason, an electrode, a separator, etc. can fully be adhere | attached and integrated in all the step parts. As a result, the process of accommodating the obtained electrode assembly in the exterior body is simple and safe. In addition, since the pressure applied to all the steps of the electrode assembly precursor is uniform, the battery characteristics of all the steps in one secondary battery are also uniform.

The typical perspective view of the manufacturing device of the rechargeable battery concerning Embodiment 1 of the present invention is shown. The typical perspective view of the manufacturing apparatus of the secondary battery which concerns on Embodiment 2 of this invention is shown. The typical perspective view of the manufacturing apparatus of the secondary battery which concerns on Embodiment 3 of this invention is shown. The typical perspective view of the manufacturing apparatus of the secondary battery which concerns on Embodiment 4 of this invention is shown. The typical perspective view of the manufacturing apparatus of the secondary battery which concerns on Embodiment 5 of this invention is shown. The typical sectional view showing the relation between the press member, the electrode assembly precursor, and the lower breath board in the manufacturing device of the secondary battery concerning the present invention is shown. In the manufacturing apparatus of the secondary battery of FIG. 3, when a press member is a rigid body, the partially expanded view of the vicinity of the uppermost step part of an electrode assembly precursor is shown. In the secondary battery manufacturing apparatus of FIG. 3, when the pressing member is an elastic body, a partially enlarged view of the vicinity of the uppermost step portion of the electrode assembly precursor is shown. The typical sectional view of the electrode assembly which has a plane lamination structure is shown. The typical sectional view of the electrode assembly which has winding structure is shown. The typical sectional view of the electrode assembly which has the compound structure of a plane lamination structure and a winding structure is shown. The typical perspective view of the manufacturing apparatus of the secondary battery concerning a prior art is shown.

[Method and apparatus for producing secondary battery]
The present invention provides a method and apparatus for manufacturing a secondary battery. In this specification, the term “secondary battery” refers to a battery that can be repeatedly charged and discharged. Therefore, the “secondary battery” is not excessively bound by the name, and may include, for example, “electric storage device”.

Hereinafter, a method for manufacturing a secondary battery of the present invention will be described in detail with reference to the drawings showing a secondary battery manufacturing apparatus and the like. In the present specification, various elements in the drawings are merely schematically and exemplarily shown for understanding of the present invention, and the appearance and size ratio may be different from the actual ones. The “vertical direction”, “left / right direction”, and “front / back direction” used directly or indirectly in this specification correspond to directions corresponding to the vertical direction, left / right direction, and front / back direction in the drawing, respectively. Unless otherwise specified, the same reference numerals or symbols indicate the same members or the same meaning contents except that the shapes are different.

(Dry bonding process)
The method for manufacturing a secondary battery of the present invention includes a dry bonding step. The dry bonding process is a process of applying pressure to the electrode assembly precursor in the thickness direction. An electrode assembly precursor is an intermediate or intermediate structure of an electrode assembly that includes a positive electrode, a negative electrode, and a separator, and in which the positive electrode and the negative electrode are simply arranged alternately via the separator. . In other words, the electrode assembly precursor is in a state that can be formed into an electrode assembly by bonding and integration simply by being pressed in a dry bonding process. Specifically, components such as a positive electrode, a negative electrode, and a separator are simply laminated. It is a layered product in the state of being. In the dry bonding process, the electrodes (positive electrode and negative electrode) constituting the electrode assembly precursor and the separator are bonded and integrated to obtain an electrode assembly. For this reason, the accommodation process to the exterior body of the obtained electrode assembly becomes safe and simple. Also, the thickness and shape of the electrode assembly can be controlled. The dry adhesion means adhesion in a state where members (for example, a positive electrode, a negative electrode, a separator, and the like) constituting the electrode assembly precursor are not wetted by the electrolyte.

The electrode assembly precursor 1 has a stepped portion 10 as shown in FIGS. 1A and 1B. The step portion is a discontinuous portion of the upper surface that is configured by two upper surfaces having different heights in a side view, and the height of the steps locally changes between the two upper surfaces. The side view is a state when an object (for example, an electrode assembly precursor) is placed and viewed from the side in the thickness (height) direction, and is in agreement with the side view. The placement is placement in which the surface (plane) having the largest area constituting the appearance of the object (for example, the electrode assembly precursor) is the bottom surface. Side view includes side view by fluoroscopy. That is, as shown in FIG. 1A and FIG. 1B, the stepped portion is not only a stepped portion that can clearly distinguish the height difference when viewed from the side, but the height difference when viewed from the side is actually Including a step portion that cannot be discriminated but can be discriminated by fluoroscopy. In other words, the stepped portion includes not only a stepped portion providing a low stepped portion having a thickness thinner than its periphery at the end portion in plan view but also a stepped portion providing the low stepped portion at the center portion. The plan view is a state when an object (for example, an electrode assembly precursor) is placed and viewed from directly above in the thickness (height) direction, and is in agreement with the plan view. The stepped portion is usually composed of two upper surfaces having different heights and a side surface 10a connecting the two upper surfaces therebetween. The stepped portion is each component when it is assumed that the electrode assembly precursor 1 is divided into components in the thickness direction on the side surface 10a constituting the stepped portion 10, and usually has a thickness for each stepped portion. However, the thickness is substantially constant at each step. The upper surface is an upper surface when an object (for example, an electrode assembly precursor) is placed. In FIG. 1A and FIG. 1B, the electrode assembly precursor 1 has two step portions 10, but may have only one step portion 10, or may have three or more steps. . FIG. 1A is a schematic perspective view of a secondary battery manufacturing apparatus according to Embodiment 1 of the present invention. FIG. 1B is a schematic perspective view of a secondary battery manufacturing apparatus according to Embodiment 2 of the present invention.

In the dry bonding process, the step assembly pressing method is adopted to press the electrode assembly precursor 1 to obtain the electrode assembly. Specifically, in the stepped portion pressing method, as shown in FIGS. 1A and 1B, the electrode assembly precursor 1 is pressed using a pressing member 3 having a press surface 3 a corresponding to the stepped shape of the stepped portion 10. Thus, an electrode assembly is obtained. The press surface 3 a corresponding to the step shape of the step portion 10 is a press surface 3 a having a shape corresponding to the shape of the surface (upper surface) on the step portion 10 side of the electrode assembly precursor 1. In other words, the press surface 3a corresponding to the step shape of the step portion 10 has the electrode assembly precursor 1 such that the press member 3 has a step portion 30 that fits with the step portion 10 of the electrode assembly precursor 1. It is the side surface. For example, it can be said that the press surface 3 a of the press member 3 has a shape complementary to the surface (upper surface) on the stepped portion 10 side of the electrode assembly precursor 1. Specifically, the press surface 3a of the press member 3 is formed on all the upper surfaces (for example, 11a) of all the step portions (for example, 11, 12, and 13) provided by all the step portions 10 in the electrode assembly precursor 1. , 12a and 13a) can be directly or indirectly abutted during pressing. By using such a press member 3, not only the uppermost step (for example, 11) of the electrode assembly precursor but also the step portions (for example, 12, 13) other than the uppermost step, Pressure can be applied. For this reason, an electrode, a separator, etc. can fully be adhere | attached and integrated in all the step parts. The manufacturing apparatus of the secondary battery of the present invention shown in FIG. 1A and FIG. 1B is a pressing device using a stepped portion pressing method, and includes a pressing member 3 having a pressing surface 3a corresponding to the stepped shape of the stepped portion 10 and the pressing member 3. The press plate 35 is disposed opposite to the press plate 35.

The step size k (for example, k1 and k2) of the step portion 30 of the press member 3 matches the step size h (for example, h1 and h2) of the step portion 10 of the electrode assembly precursor 1 to which each step portion 30 corresponds. It is preferable to make it. This is because the pressure can be more uniformly applied to the upper surfaces of all the step portions of the electrode assembly precursor 1, and better battery characteristics (for example, life characteristics) can be obtained. The step size h of the step portion 10 of the electrode assembly precursor 1 may be the step size (design size) of the step portion 10 when the electrode assembly precursor becomes an electrode assembly by pressing.

The pressing is preferably performed under a uniform pressure condition for the pressure applied to the electrode assembly precursor 1. That is, the pressure (surface pressure) applied to the upper surfaces (for example, 11a, 12a and 13a) of all the step portions (for example, 11, 12 and 13) in the electrode assembly precursor 1 is 5% or less in uniformity. It is preferable to have. Thereby, the pressure applied to all the steps becomes more uniform, and the uniformity of the battery characteristics is further improved. Such uniformity can be easily achieved by matching the step size k of the step portion 30 with the step size h of the step portion 10 as described above.

The uniformity of the pressure applied to the upper surface of all steps can be calculated by the pressure measured at any 10 points in each step and the following formula:
Uniformity (%) = {(Pmax−Pmin) / Pmin} × 100
Pmax: the maximum pressure among the pressures measured at all steps;
Pmin: The minimum pressure among the pressures measured at all steps.

The pressure at each step can be measured with a load cell.

In FIG. 1A and FIG. 1B, the press member 3 has two step portions 30, but the present invention is not limited to this, and depending on the number of step portions 10 included in the electrode assembly precursor 1, the press member 3 has steps. You may have only one part 30, or you may have three or more.

The pressing member 3 has a stepped portion 30 that fits with the stepped portion 10 of the electrode assembly precursor 1, whereby the upper surfaces of all the stepped portions of the electrode assembly precursor 1 and the direct or It is a member having a press surface 3a that can be contacted indirectly. The press member 3 may be, for example, one (31) of the press plates (31, 35) of the press device as shown in FIG. 1A, or one press plate (31) as shown in FIG. 1B. It may be a pressing jig (32) disposed between the electrode assembly precursor 1 and the electrode assembly precursor 1. That is, in the present invention, as shown in FIG. 1A, the press plate 31 as the press member 3 may have a press surface 3a corresponding to the step shape of the step portion 10, or as shown in FIG. 1B. In addition, the pressing jig 32 as the pressing member 3 may have a pressing surface 3 a corresponding to the step shape of the stepped portion 10.

The press plate is usually a

member

31 or 35 that is provided in two in one press device and pressurizes an object between them. In FIG. 1A, one of the press plates 31 is used as the press member 3. In the present invention, the other press plate 35 may be used as the press member 3 according to the shape of the electrode assembly precursor 1.

The press jig is an auxiliary member 32 interposed between the press plate and the electrode assembly precursor. In FIG. 1B, a pressing jig 32 is used as the pressing member 3 between one of the

pressing plates

31 and 35 and the electrode assembly precursor 1. In the present invention, a press jig (not shown) may be used as the press member 3 between the other press plate 35 and the electrode assembly precursor 1 according to the shape of the electrode assembly precursor 1. Good.

When a press jig 32 is used as the press member 3, as shown in FIG. 1C, a plurality of electrode assemblies precursors 1 are simultaneously pressed using a plurality of press jigs 32, whereby a plurality of electrode assemblies are formed. Can be obtained at the same time. FIG. 1C is a schematic perspective view of a secondary battery manufacturing apparatus according to Embodiment 3 of the present invention. The secondary battery manufacturing apparatus (particularly the electrode assembly manufacturing apparatus) of FIG. 1C is a press apparatus 50. Specifically, the pressure in the z direction is applied to the press plate 31 via the movable plate 52 by the rotation of the bolt 51. And a press plate 35 (fixed plate). At this time, between the press plate 31 and each electrode assembly precursor 1, a press jig 32 as a press member 3 is interposed adjacent to each electrode assembly precursor 1. Thereby, a pressure can be uniformly and simultaneously applied to all the steps in the plurality of electrode assembly precursors 1.

In FIG. 1A, FIG. 1B, and FIG. 1C, although the press member 3 is shown as one member, as shown to FIG. 2A, the press member 3 is divided | segmented and the said two or more divided | segmented press members ( 3p, 3q, 3r) may be used for each step (11, 12, 13) of the electrode assembly precursor 1. Thereby, the pressure applied to the electrode assembly precursor 1 can be adjusted for each step (11, 12, 13). For this reason, the pressure applied to all the steps can be adjusted more uniformly, and the uniformity of the battery characteristics is further improved. At this time, as shown in FIG. 2B, the lower press plate 35 is also divided, and the electrode assembly precursor 1 has two or more divided lower press plates (35p, 35q, 35r). You may press for every step part (11, 12, 13). This makes it easy to adjust the pressure applied to the electrode assembly precursor 1 for each step (11, 12, 13). FIG. 2A shows a schematic perspective view of a secondary battery manufacturing apparatus according to Embodiment 4 of the present invention. FIG. 2B shows a schematic perspective view of a secondary battery manufacturing apparatus according to Embodiment 5 of the present invention.

The press member 3 may be made of any material as long as pressure can be applied to the upper surfaces (for example, 11a, 12a, and 13a) of all the step portions (for example, 11, 12, and 13) of the electrode assembly precursor 1. Good. The pressing member 3 may be a rigid body or an elastic body, for example, but is preferably a rigid body. As shown in FIG. 3, when the electrode assembly precursor 1 is pressed between the press member 3 and the lower press plate 35, the press member 3 is a rigid body. The corner portion 15 can be further pressed with a uniform pressure. Furthermore, since the press member 3 is not deformed when pressure is applied, damage to the electrode assembly precursor 1 can be prevented. On the other hand, when the press member 3 is an elastic body, as shown in FIG. 5, the press member 3 is elastically deformed by pressure, so that excessive pressure is applied to the corner portion 15 of the step portion and / or the step portion The electrode assembly precursor 1 may be damaged by pressure applied to the side surface 10a. FIG. 3 is a schematic cross-sectional view showing the relationship among the press member 3, the electrode assembly precursor 1, and the lower breath plate 35 in the secondary battery manufacturing apparatus according to the present invention. FIG. 4 is a partially enlarged view of the vicinity of the uppermost step portion of the electrode assembly precursor 1 when the press member 3 is a rigid body in the secondary battery manufacturing apparatus of FIG. 3. FIG. 5 shows a partially enlarged view of the vicinity of the uppermost step portion of the electrode assembly precursor 1 when the press member 3 is an elastic body.

The rigid body means an object having rigidity, and more specifically, an object that does not deform even by a normal pressure applied to the press member 3. More specifically, the rigid body is made of a material having a Young's modulus of 1 GPa or more and 500 GPa or less. As a material that can constitute a rigid press member, for example, a polymer material (for example, phenol resin, polypropylene resin, polyester resin (particularly polyethylene terephthalate resin), polyimide resin, polyphenylene sulfide resin, polyvinyl formal resin, polyurethane resin, Polyamideimide resin, polyamide resin, etc.), and metal materials (for example, iron, aluminum, gold, silver, copper, stainless steel, etc.).

The elastic body means an object having elasticity, and more specifically, an object that is deformed by a normal pressure applied to the press member 3 but returns to its original shape when the force is removed. More specifically, the elastic body is made of a material having a Young's modulus of 0.005 GPa or more and less than 1 GPa (particularly 0.005 GPa or more and 0.5 GPa or less). Examples of the material that can constitute the press member as the elastic body include rubber materials similar to the rubber materials included in the elastic sheet described later.

In the dry bonding process, an elastic sheet (not shown) may be interposed between the press member 3 and the electrode assembly precursor 1. In particular, when the press member 3 is a rigid body, it is more preferable to interpose an elastic sheet between the press member 3 and the electrode assembly precursor 1. This is because the pressure can be more uniformly applied to the upper surface of the step portion of the electrode assembly precursor 1. The elastic sheet includes a rubber material. Examples of rubber materials include silicone rubber, isoprene rubber, butadiene rubber, styrene / butadiene rubber, chloroprene rubber, nitrile rubber, polyisobutylene, ethylene propylene rubber, chlorosulfonated polyethylene, acrylic rubber, fluorine rubber, epichlorohydrin rubber, and urethane rubber. It may be at least one rubber material selected from the group consisting of and the like. The thickness of the elastic sheet is usually 100 μm or more and 5 mm or less.

In the dry bonding process, the pressure on the electrode assembly precursor surface is not particularly limited as long as adhesion and bonding between the electrodes (positive electrode and negative electrode) and the separator are promoted, and is usually a pressure higher than atmospheric pressure. . Specifically, the pressure is usually in the range of 0.1 MPa or more and 5.0 MPa or less, and preferably in the range of 0.5 MPa or more and 3.0 MPa or less from the viewpoint of further promoting the adhesion.

In the dry bonding process, the temperature of the electrode assembly precursor is not particularly limited as long as adhesion and bonding between the electrode (positive electrode and negative electrode) and the separator are promoted. For example, the temperature is maintained within a range of 25 ° C to 110 ° C. May be. The electrode assembly precursor is preferably maintained at a temperature in the range of 50 ° C. or higher and 100 ° C. or lower, more preferably 70 ° C., from the viewpoint of further promoting adhesion between the electrode (positive electrode and negative electrode) and the separator. The temperature is maintained at 90 ° C. or lower. Specifically, the temperature of the electrode assembly precursor can be maintained within the above range by heating the pressing member 3 to the above temperature in this step. The temperature of the electrode assembly precursor may be a set temperature of the press member.

In the dry bonding step, the pressing time is not particularly limited as long as the adhesion between the electrode (positive electrode and negative electrode) and the separator is promoted, and is usually 1 second or more and 10 minutes or less. To preferably within a range of 5 seconds to 9 minutes, and more preferably within a range of 10 seconds to 8 minutes.

The dry bonding step may be performed using, for example, the apparatus shown in FIGS. 1A, 1B, and 1C described above. From the viewpoint of applying high pressure, it is preferable to use the apparatus shown in FIGS. 1A and 1B.

(Electrode assembly precursor)
As described above, the electrode assembly precursor 1 includes the positive electrode, the negative electrode, and the separator, and the intermediate or intermediate structure of the electrode assembly in which the positive electrode and the negative electrode are simply arranged alternately via the separator. And has one or more step portions 10.

In the one or more step portions 10 of the electrode assembly precursor 1, the step size (level difference) of each step portion (that is, the height difference between two upper surfaces constituting each step portion) h is not particularly limited. The step size h of each step portion is independently 100 μm or more and 10 mm or less, particularly 500 μm or more and 8 mm or less, from the viewpoint of the uniformity of pressure to all the step portions and the electronic device application of the secondary battery. Preferably, it is 1 mm or more and 5 mm or less. As described above, the step size h of the step portion 10 of the electrode assembly precursor 1 is the step size (design size) of the step portion 10 when the electrode assembly precursor becomes an electrode assembly by pressing. It's okay. The step size (design dimension) of the step portion of the electrode assembly is usually equal to the step size (design dimension) of the step portion of the secondary battery as the final product.

The step size h of each step portion 10 is the number of electrodes constituting the electrode assembly and the electrode assembly having a winding structure when the electrode assembly has a planar laminated structure and / or a winding structure which will be described later. It can be controlled by adjusting the number of windings in.

The stepped portion is useful for arranging a substrate or accommodating an adhesive layer, which will be described later. That is, by arranging the substrate on the upper surface of the lower step portion in the step portion, it is possible to secure a space for arranging the substrate. When the step portion accommodates the adhesive layer used when the secondary battery is installed in the casing of the electronic device, an accommodation space for the adhesive layer can be secured. As a result of these, the energy density of the secondary battery is improved.

In FIG. 1A, FIG. 1B, and FIG. 1C, all the upper surfaces of the electrode assembly precursor 1 have a planar shape that is substantially parallel to a horizontal surface (for example, the bottom surface when mounted). The three-dimensional precursor 1 may have an upper surface that is inclined with respect to a horizontal plane and / or an upper surface that has a curved shape. Even if the electrode assembly precursor 1 has such an upper surface shape in the present invention, the press member 3 has the press surface 3a corresponding to the shape, so that all the steps of the electrode assembly precursor 1 have. The pressure can be uniformly applied to the part.

The planar view shape of the electrode assembly precursor 1 is not particularly limited, and may be a rectangular shape or an irregular shape in the planar view. The plan view is a state when an object (for example, an electrode assembly precursor) is placed and viewed from directly above in the thickness (height) direction, and is in agreement with the plan view. The irregular shape in the plan view shape of the electrode assembly precursor is a shape having a notch in the plan view. The notch is a part where a part of the cutout is intentionally lost from the initial shape. The initial shape before the formation of the notch is usually rectangular. The planar view shape of the notch is not particularly limited, and examples thereof include a rectangular shape, a triangular shape, a fan shape, a semicircular shape, and a circular shape. The rectangular shape includes so-called rectangles and squares, and is usually a rectangle.

As shown in FIG. 6, the electrode assembly precursor 1 is a plane in which a plurality of electrode units (electrode constituent layers) including a positive electrode 5, a negative electrode 6, and a separator 7 disposed between the positive electrode and the negative electrode are stacked in a planar shape. You may have a laminated structure. The structure of the electrode assembly precursor 1 is not limited to a planar laminated structure. For example, as shown in FIG. 7, an electrode unit (electrode configuration including a positive electrode 5, a negative electrode 6, and a separator 7 disposed between the positive electrode and the negative electrode. Layer) may be wound in a roll shape (winding laminated structure) (jelly roll type), or a composite structure of a planar laminated structure and a wound structure as shown in FIG. You may have. In addition, for example, the electrode assembly precursor may have a so-called stack and folding structure in which a positive electrode, a separator, and a negative electrode are stacked on a long film and then folded. From the viewpoint of applying a more uniform pressure to all the step portions of the electrode assembly precursor, the electrode assembly precursor 1 preferably has a planar laminated structure.

The positive electrode is composed of at least a positive electrode material layer and a positive electrode current collector (foil), and it is sufficient that the positive electrode material layer is provided on at least one side of the positive electrode current collector. For example, in the positive electrode, a positive electrode material layer may be provided on both surfaces of the positive electrode current collector, or a positive electrode material layer may be provided on one surface of the positive electrode current collector. A positive electrode preferable from the viewpoint of further increasing the capacity of the secondary battery is provided with a positive electrode material layer on both surfaces of the positive electrode current collector. The positive electrode material layer contains a positive electrode active material.

The negative electrode is composed of at least a negative electrode material layer and a negative electrode current collector (foil), and it is sufficient that the negative electrode material layer is provided on at least one surface of the negative electrode current collector. For example, in the negative electrode, a negative electrode material layer may be provided on both surfaces of the negative electrode current collector, or a negative electrode material layer may be provided on one surface of the negative electrode current collector. A negative electrode preferable from the viewpoint of further increasing the capacity of the secondary battery is provided with a negative electrode material layer on both surfaces of the negative electrode current collector. The negative electrode material layer contains a negative electrode active material.

The positive electrode active material included in the positive electrode material layer and the negative electrode active material included in the negative electrode material layer are materials directly involved in the transfer of electrons in the secondary battery, and are the main materials of the positive and negative electrodes that are responsible for charge / discharge, that is, the battery reaction. is there. More specifically, ions are brought into the electrolyte due to the “positive electrode active material included in the positive electrode material layer” and the “negative electrode active material included in the negative electrode material layer”, and the ions are interposed between the positive electrode and the negative electrode. Then, the electrons are transferred and the electrons are delivered and charged and discharged. As will be described later, the positive electrode material layer and the negative electrode material layer are particularly preferably layers capable of occluding and releasing lithium ions. That is, a secondary battery in which lithium ions move between the positive electrode and the negative electrode through the electrolyte to charge and discharge the battery is preferable. When lithium ions are involved in charging / discharging, the secondary battery according to the present invention corresponds to a so-called “lithium ion battery”.

The positive electrode active material of the positive electrode material layer is made of, for example, a granular material, and it is preferable that a binder is included in the positive electrode material layer for sufficient contact between the particles and shape retention. Furthermore, it is also preferable that a conductive additive is included in the positive electrode material layer in order to facilitate the transmission of electrons that promote the battery reaction. Similarly, the negative electrode active material of the negative electrode material layer is made of, for example, a granular material, and it is preferable that a binder is included for sufficient contact and shape retention between the particles, and smooth transmission of electrons that promote the battery reaction. In order to do so, a conductive aid may be included in the negative electrode material layer. Thus, because of the form in which a plurality of components are contained, the positive electrode material layer and the negative electrode material layer can also be referred to as “positive electrode composite material layer” and “negative electrode composite material layer”, respectively.

The positive electrode active material is preferably a material that contributes to occlusion and release of lithium ions. From this point of view, the positive electrode active material is preferably, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material is preferably a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese, and iron. That is, in the positive electrode material layer of the secondary battery according to the present invention, such a lithium transition metal composite oxide is preferably included as a positive electrode active material. For example, the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a part of those transition metals replaced with another metal. Although such a positive electrode active material may be included as a single species, two or more types may be included in combination. In a more preferred embodiment, the positive electrode active material contained in the positive electrode material layer is lithium cobalt oxide.

The binder that can be included in the positive electrode material layer is not particularly limited, but includes polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and Mention may be made of at least one selected from the group consisting of polytetrafluoroethylene and the like. The conductive auxiliary agent that can be included in the positive electrode material layer is not particularly limited, but carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, graphite, carbon nanotube, and vapor phase growth. Examples thereof include at least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. In a more preferred aspect, the binder of the positive electrode material layer is polyvinylidene fluoride, and in another more preferred aspect, the conductive additive of the positive electrode material layer is carbon black. In a more preferred embodiment, the binder and conductive additive of the positive electrode material layer are a combination of polyvinylidene fluoride and carbon black.

The negative electrode active material is preferably a material that contributes to occlusion and release of lithium ions. From this point of view, the negative electrode active material is preferably, for example, various carbon materials, oxides, or lithium alloys.

Examples of various carbon materials of the negative electrode active material include graphite (natural graphite, artificial graphite), hard carbon, soft carbon, diamond-like carbon, and the like. In particular, graphite is preferable in that it has high electron conductivity and excellent adhesion to the negative electrode current collector. Examples of the oxide of the negative electrode active material include at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, and the like. The lithium alloy of the negative electrode active material may be any metal that can be alloyed with lithium. For example, Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, It may be a binary, ternary or higher alloy of a metal such as La and lithium. Such an oxide is preferably amorphous in its structural form. This is because deterioration due to non-uniformity such as crystal grain boundaries or defects is less likely to be caused. In a more preferred embodiment, the negative electrode active material of the negative electrode material layer is artificial graphite.

The binder that can be included in the negative electrode material layer is not particularly limited, but is at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin, and polyamideimide resin. Can be mentioned. In a more preferred embodiment, the binder contained in the negative electrode material layer is styrene butadiene rubber. The conductive aid that can be included in the negative electrode material layer is not particularly limited, but carbon black such as thermal black, furnace black, channel black, ketjen black, and acetylene black, graphite, carbon nanotube, and vapor phase growth. Examples thereof include at least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel, aluminum and silver, and polyphenylene derivatives. In addition, the component resulting from the thickener component (for example, carboxymethylcellulose) used at the time of battery manufacture may be contained in the negative electrode material layer.

In a more preferred embodiment, the negative electrode active material and the binder in the negative electrode material layer are a combination of artificial graphite and styrene butadiene rubber.

The positive electrode current collector and the negative electrode current collector used for the positive electrode and the negative electrode are members that contribute to collecting and supplying electrons generated in the active material due to the battery reaction. Such a current collector may be a sheet-like metal member and may have a porous or perforated form. For example, the current collector may be a metal foil, a punching metal, a net or an expanded metal. The positive electrode current collector used for the positive electrode is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel and the like, and may be, for example, an aluminum foil. On the other hand, the negative electrode current collector used for the negative electrode is preferably made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel and the like, and may be, for example, a copper foil.

The separator is a member provided from the viewpoint of preventing short circuit due to contact between the positive and negative electrodes and holding the electrolyte. In other words, the separator can be said to be a member that allows ions to pass while preventing electronic contact between the positive electrode and the negative electrode. Preferably, the separator is a porous or microporous insulating member and has a film form due to its small thickness. Although only illustrative, a polyolefin microporous film may be used as the separator. In this regard, the microporous membrane used as the separator may include, for example, only polyethylene (PE) or only polypropylene (PP) as the polyolefin. Furthermore, the separator may be a laminate composed of “a microporous membrane made of PE” and “a microporous membrane made of PP”.

The separator usually has an adhesive layer on the surface (both sides), but an adhesive layer in the form of a film may exist independently between the separator and the electrode (positive electrode and negative electrode). The material constituting the adhesive layer is not particularly limited as long as it is a polymer that exhibits adhesiveness by melting and solidifying without being dissolved in the electrolyte described later. For example, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer Examples include coalescence and acrylic resin. The thickness of the adhesive layer is usually 0.5 μm or more and 5 μm or less. The separator may have an inorganic particle coat layer on the surface.

(Other processes)
The electrode assembly obtained in the dry bonding process is usually subjected to a so-called wet bonding process and an initial charging process after being enclosed in an outer package together with an electrolyte. When enclosing the electrode assembly and the electrolyte in the exterior body, usually, two external terminals are connected to the electrode (positive electrode or negative electrode) via the current collecting lead, and as a result, led out from the exterior body.

Usually, the electrode assembly and the electrolyte are sealed in the exterior body by sealing the interior (opening) of the exterior body after the electrode assembly is accommodated in the exterior body and the electrolyte is injected into the exterior body. Achieved.

In the sealing process, the inside of the exterior body is usually sealed under reduced pressure. That is, the opening of the exterior body is sealed while the electrode assembly is accommodated and the inside of the exterior body into which the electrolyte is injected is maintained in a reduced pressure state.

The sealing method is not particularly limited as long as the sealing of the opening of the exterior body is achieved. For example, when the exterior body is a flexible pouch described later, the sealing may be achieved by a heat seal method. For example, when the exterior body is a hard case described later, sealing may be achieved by a laser irradiation method.

Electrolyte helps the movement of metal ions released from the electrodes (positive and negative electrodes). The electrolyte may be a “non-aqueous” electrolyte, such as an organic electrolyte and an organic solvent, or may be a “aqueous” electrolyte containing water. The secondary battery of the present invention is preferably a non-aqueous electrolyte secondary battery in which an electrolyte containing a “non-aqueous” solvent and a solute is used as an electrolyte. The electrolyte may have a form such as liquid or gel (in the present specification, “liquid” non-aqueous electrolyte is also referred to as “non-aqueous electrolyte solution”).

As a specific nonaqueous electrolyte solvent, a solvent containing at least carbonate is preferable. Such carbonates may be cyclic carbonates and / or chain carbonates. Although not particularly limited, examples of the cyclic carbonates include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC). be able to. Examples of the chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC). In one preferred embodiment of the present invention, a combination of cyclic carbonates and chain carbonates is used as the non-aqueous electrolyte, for example, a mixture of ethylene carbonate and diethyl carbonate.

As specific nonaqueous electrolyte solutes, for example, Li salts such as LiPF ₆ and LiBF ₄ are preferably used.

The exterior body is preferably a flexible pouch (soft bag), but may be a hard case (hard housing). When the exterior body is a flexible pouch, the flexible pouch is usually formed from a laminate film, and sealing is achieved by heat-sealing the peripheral edge. As the laminate film, a film obtained by laminating a metal foil and a polymer film is generally used. Specifically, a film having a three-layer structure including an outer layer polymer film / metal foil / inner layer polymer film is exemplified. The outer layer polymer film is for preventing damage to the metal foil due to permeation and contact of moisture and the like, and polymers such as polyamide and polyester can be suitably used. The metal foil is for preventing the permeation of moisture and gas, and a foil of copper, aluminum, stainless steel or the like can be suitably used. The inner layer polymer film is for protecting the metal foil from the electrolyte accommodated therein, and for melting and sealing at the time of heat sealing, and polyolefin or acid-modified polyolefin can be suitably used. The thickness of the laminate film is not particularly limited, and is preferably 1 μm or more and 1 mm or less, for example.

When the exterior body is a hard case, the hard case is usually formed from a metal plate, and sealing is achieved by irradiating the peripheral edge with a laser. As the metal plate, a metal material made of aluminum, nickel, iron, copper, stainless steel or the like is common. The thickness of a metal plate is not specifically limited, For example, 1 micrometer or more and 1 mm or less are preferable.

As the current collecting lead, any current collecting lead used in the field of secondary batteries can be used. Such a current collecting lead may be made of a material capable of achieving electron movement, and is usually made of a conductive material such as aluminum, nickel, iron, copper, and stainless steel. The form of the current collecting lead is not particularly limited, and may be, for example, a linear shape or a plate shape.

As the external terminal, any external terminal used in the field of secondary batteries can be used. Such an external terminal may be made of a material capable of achieving electron movement, and is usually made of a conductive material such as aluminum, nickel, iron, copper, and stainless steel. The form of the external terminal 5 is not particularly limited, and is usually plate-shaped. The external terminal 5 may be electrically and directly connected to the substrate, or may be electrically and indirectly connected to the substrate via another device. The current collecting lead can also be used as an external terminal.

The wet adhesion process is a process of applying pressure in the thickness direction to the secondary battery precursor obtained by enclosing the electrode assembly and the electrolyte in the exterior body. The wet adhesion process promotes adhesion between the electrodes (positive electrode and negative electrode) and the separator, and as a result, the uniformity of battery characteristics is further improved. In addition, the thickness and shape of the secondary battery can be controlled. The wet adhesion means adhesion in a state where members (for example, a positive electrode, a negative electrode, a separator, and the like) that the secondary battery precursor has in the outer package are wetted by an electrolyte.

The initial charging process is the first charge / discharge process of the secondary battery precursor performed for the purpose of forming a solid electrolyte interface film (hereinafter referred to as “SEI film”) on the negative electrode surface. Also called charging process or conditioning process. By uniformly forming the SEI film on the negative electrode surface, the decomposition of the electrolyte component is suppressed in the secondary battery, and the capacity of the secondary battery can be stabilized and the life can be extended. In the initial charging step, charging may be performed at least once, and charging / discharging is usually performed once or more. One charge / discharge includes one charge and one subsequent discharge. If charging / discharging is performed twice or more, the charging-discharging is repeated the corresponding number of times.

[substrate]
In the secondary battery manufactured by the method of the present invention, a substrate may be disposed using the step portion. In other words, the substrate may be disposed on the upper surface of the low step portion constituting the step portion of the secondary battery. Thereby, the arrangement | positioning space of a board | substrate is securable.

The substrate may be a so-called rigid substrate or a flexible substrate. As the rigid substrate, any rigid substrate used in the field of substrates used with secondary batteries can be used, and examples thereof include a glass / epoxy resin substrate.

Examples of the substrate include an electronic circuit substrate such as a printed circuit board, a semiconductor substrate such as a silicon wafer, and a glass substrate such as a display panel.

When the board is a so-called protection circuit board for preventing overcharge, overdischarge and overcurrent of the secondary battery, a secondary battery pack is constituted by the protection circuit board and the secondary battery.

The secondary battery obtained according to the present invention can be used in various fields where power storage is assumed. The secondary battery obtained according to the present invention, in particular the non-aqueous electrolyte secondary battery, is merely an example, and the electric / information / communication field (for example, a mobile phone, a smart phone, a smart watch, a notebook) Mobile devices such as personal computers, digital cameras, activity meters, arm computers and electronic paper), home / small industrial applications (eg, power tools, golf carts, home / nursing / industrial robots), large industries Applications (for example, forklifts, elevators, bay harbor cranes), transportation systems (for example, hybrid cars, electric vehicles, buses, trains, electric assist bicycles, electric motorcycles, etc.), power system applications (for example, various power generation) , Road conditioners, smart grids, general home storage energy storage systems Field), IoT areas such as arm, as well as, it is possible to utilize space and deep sea applications (for example, spacecraft, areas such as submersible research vessel) and the like.

1: 1a: 1b: 1c: Electrode assembly precursor 3: Press member 3a: Press surface of press member 5: Positive electrode 6: Negative electrode 7: Separator 10: Stepped portion of electrode assembly precursor 11: Top step 11a: Upper surface of the uppermost step portion 12:13: Step portion other than the uppermost step portion 15: Corner portion of the step portion 30: Step portion of the pressing member 31: Upper press plate 35: Lower press plate

Claims

A positive electrode and a negative electrode are alternately arranged via separators, and an electrode assembly precursor having a stepped portion is pressed using a pressing member having a press surface corresponding to the stepped shape of the stepped portion, to thereby form an electrode A method for manufacturing a secondary battery, wherein an assembly is obtained.
The method for manufacturing a secondary battery according to claim 1, wherein the electrode assembly precursor is bonded and integrated by the pressing.
The manufacturing of the secondary battery according to claim 1 or 2, wherein the pressing member is a pressing plate of a pressing device, or a pressing jig disposed between the pressing plate and the electrode assembly precursor. Method.
The method for manufacturing a secondary battery according to any one of claims 1 to 3, wherein the press member is a rigid body.
The method for manufacturing a secondary battery according to any one of claims 1 to 4, wherein pressing is performed with an elastic sheet interposed between the pressing member and the electrode assembly precursor.
The said press member is divided | segmented and it presses for every step part which the said electrode assembly precursor has based on the said level | step-difference part using two or more said divided | segmented press members. 6. A method for producing a secondary battery according to any one of.
The method for manufacturing a secondary battery according to any one of claims 1 to 6, wherein the pressing is performed under a uniform pressure condition with respect to a pressure applied to the electrode assembly precursor.
The method for manufacturing a secondary battery according to any one of claims 1 to 7, wherein a step size of the step portion is 100 µm or more and 10 mm or less.
The electrode assembly precursor has a planar laminated structure in which a plurality of electrode units including the positive electrode, the negative electrode, and the separator are stacked in a planar shape, or the electrode unit including the positive electrode, the negative electrode, and the separator is rolled. The method for producing a secondary battery according to any one of claims 1 to 8, wherein the method has a wound structure wound around or a composite structure thereof.
The method for producing a secondary battery according to any one of claims 1 to 9, wherein the positive electrode and the negative electrode have a layer capable of occluding and releasing lithium ions.
The method for producing a secondary battery according to any one of claims 1 to 10, wherein the secondary battery is a secondary battery for mobile devices.
A pressing member for alternately pressing a positive electrode and a negative electrode through separators and pressing an electrode assembly precursor having a stepped portion to obtain an electrode assembly, corresponding to the stepped shape of the stepped portion The manufacturing apparatus of a secondary battery including the press member which has the pressed surface.
The apparatus for manufacturing a secondary battery according to claim 12, wherein the electrode assembly precursor is bonded and integrated by the press.
The manufacturing of the secondary battery according to claim 12 or 13, wherein the pressing member is a pressing plate of a pressing device, or a pressing jig disposed between the pressing plate and the electrode assembly precursor. apparatus.
15. The apparatus for manufacturing a secondary battery according to claim 12, wherein the press member is a rigid body.
The secondary battery manufacturing apparatus according to any one of claims 12 to 15, further comprising an elastic sheet interposed between the press member and the electrode assembly precursor.
The said press member is divided | segmented, It presses for every step part which the said electrode assembly precursor has based on the said level | step-difference part using two or more said divided | segmented press members. 17. The secondary battery manufacturing apparatus according to any one of items 16 to 16.
The secondary battery manufacturing apparatus according to any one of claims 12 to 17, wherein the pressing is performed under a uniform pressure condition with respect to a pressure applied to the electrode assembly precursor.
The apparatus for manufacturing a secondary battery according to any one of claims 12 to 18, wherein a step size of the step portion is 100 µm or more and 10 mm or less.
The electrode assembly precursor has a planar laminated structure in which a plurality of electrode units including the positive electrode, the negative electrode, and the separator are stacked in a planar shape, or the electrode unit including the positive electrode, the negative electrode, and the separator is rolled. The apparatus for manufacturing a secondary battery according to any one of claims 12 to 19, which has a wound structure wound around or a composite structure thereof.
The secondary battery manufacturing apparatus according to any one of claims 12 to 20, wherein the positive electrode and the negative electrode have a layer capable of inserting and extracting lithium ions.
The secondary battery manufacturing apparatus according to any one of claims 12 to 21, wherein the secondary battery is a secondary battery for a mobile device.