WO2018216644A1

WO2018216644A1 - Secondary battery manufacturing method

Info

Publication number: WO2018216644A1
Application number: PCT/JP2018/019450
Authority: WO
Inventors: 達夫新野
Original assignee: 株式会社村田製作所
Priority date: 2017-05-26
Filing date: 2018-05-21
Publication date: 2018-11-29
Also published as: JP2020144975A

Abstract

The main purpose of the present invention is to provide a secondary battery manufacturing method with which a problematic phenomenon due to a guide roll for transferring an electrode precursor is reduced. Provided is a secondary battery manufacturing method comprising, for fabricating at least one of a positive electrode and a negative electrode: obtaining an electrode precursor by forming an electrode material layer on a metal sheet material for a current collector; and subjecting the electrode precursor to trimming to at least partially cut off an edge of the electrode precursor. In particular, the trimming involves cutting off the edge in such a way that the edge of the electrode precursor forms wavy irregularities.

Description

Manufacturing method of secondary battery

The present invention relates to a method for manufacturing a secondary battery. In particular, the present invention relates to a method for manufacturing a secondary battery characterized by the production of at least one of a positive electrode and a negative electrode.

Secondary batteries are so-called “storage batteries” that can be repeatedly charged and discharged, and are used in various applications. For example, secondary batteries are used in mobile devices such as mobile phones, smartphones, and notebook computers.

The secondary battery includes at least a positive electrode, a negative electrode, and a separator between them. The positive electrode is composed of a positive electrode material layer and a positive electrode current collector, and the negative electrode is composed of a negative electrode material layer and a negative electrode current collector. The secondary battery has, for example, a laminated structure in which electrode constituent layers composed of a positive electrode and a negative electrode sandwiching a separator are stacked on each other.

Special table 2015-536036 gazette Japanese Patent No. 381087 Japanese Patent No. 2015-536036

The inventor of the present application has found that there is a problem to be overcome in the conventional method of manufacturing a secondary battery, and has found that it is necessary to take measures for that. Specifically, the present inventors have found that there are the following problems.

In the production of each of the positive electrode and the negative electrode, an electrode precursor is once formed and then cut out to obtain an electrode. This will be described with reference to FIGS. 12 (a) to 12 (c). As shown in FIGS. 12A and 12B, an electrode precursor 30 is obtained by forming an electrode material layer 20 containing an electrode active material on a metal sheet material 10 to be an electrode current collector. For the electrode precursor 30, a desired electrode 40 can be obtained by cutting out a predetermined shape as shown in FIGS. 12 (b) and 12 (c). When cutting out, if the region of the metal sheet material 10 on which no electrode material layer is provided is included in the cut out shape, the tab 45 can be provided on the electrode 40.

In the continuous manufacturing process, the electrode precursor is formed while feeding the metal sheet material in a predetermined direction. Specifically, for example, the metal sheet material is moved while being unwound in a roll shape, and an electrode material raw material is supplied to the metal sheet material to form the electrode precursor 30. A guide roll can be used for the movement of the metal sheet material, that is, the transport of the electrode precursor obtained from the sheet material. In this case, the electrode precursor layer 30 is continuously formed by forming the electrode material layer 20 on the metal sheet material while moving / conveying the metal sheet material in a predetermined direction via the guide roll.

For such a continuous manufacturing process, the inventors of the present application have found that conveyance by a guide roll can cause a surprisingly inconvenient phenomenon to the electrode precursor. Specifically, it has been found that the electrode precursor being transported can be adversely affected by the guide rolls used for the transport.

The transported electrode precursor may be subjected to a cutting process called “trimming” or “pre-trimming” (hereinafter also simply referred to as “trimming process”). The edge of the electrode precursor may be cut off at least partially. It has now been found that the trimmed electrode precursor can be adversely affected by the guide roll during transport by the guide roll. In particular, the trimmed electrode precursor is easily cut or easily broken from the trimmed local portion due to an external force applied from the guide roll (particularly due to an external force that causes the electrode precursor to bend). I understood.

The present invention has been made in view of such problems. That is, a main object of the present invention is to provide a method for manufacturing a secondary battery in which an inconvenient phenomenon caused by a guide roll used for transporting an electrode precursor is reduced.

The inventor of the present application tried to solve the above-mentioned problem by addressing in a new direction rather than responding on the extension of the prior art. As a result, the inventors have reached an invention of a method for manufacturing a secondary battery in which the main object is achieved.

A method for manufacturing a secondary battery according to the present invention includes:
Production of at least one of a positive electrode and a negative electrode
Forming an electrode material layer on a metal sheet material to be an electrode current collector to obtain an electrode precursor, and applying trimming to the electrode precursor to at least partially cut off the edge of the electrode precursor,
Trimming is performed so that the edges of the electrode precursor have wave-like irregularities.

In the manufacturing method of the present invention, the trimming process is performed so that the edge of the electrode precursor has a wave-shaped unevenness, so that an inconvenient phenomenon caused by the guide roll used for transporting the electrode precursor can be reduced. In particular, even in a continuous manufacturing process in which a guide roll is used, a phenomenon in which the electrode precursor is cut or torn by an external force received from the guide roll is reduced. Therefore, a desired electrode precursor can be obtained by the present invention, and thus a desired electrode can be obtained.

More specifically, even when the trimmed electrode precursor is transported while being displaced so as to be bent due to the guide rolls, “cutting or tearing of the electrode precursor starting from the local location, etc. The “inconvenient phenomenon” is reduced by the “waveform irregularities of the electrode precursor edge”.

The top view which showed typically the process aspect in the manufacturing method which concerns on one Embodiment of this invention Schematic showing a continuous manufacturing process using guide rolls The top view which showed typically the aspect of the curved unevenness | corrugation containing both a corrugated concave and a corrugated convex The top view which showed typically the aspect in which the waveform corrugation and corrugation which adjoin each other of a corrugated unevenness share a part mutually Plan view schematically showing a preferred embodiment with trimming (FIG. 5A: preferred embodiment A in which only the pole material non-formation region is cut off, FIG. 5B: not only the pole material non-formation region but also the pole material Preferred embodiment B) to cut off so as to partially include the formation region Schematic explanatory diagram for explaining a mode in which the edge contour of the electrode precursor has a geometric singular point (FIG. 6A: tip (point), FIG. 6B: jump point, FIG. 6 (C): Corner point) Schematic explanatory diagram for explaining a mode in which the edge contour of the electrode precursor has a geometric singular point (FIG. 7A: isolated point, FIG. 7B: double point, FIG. 7C): Self-contact point, Fig. 7 (D): 3 points) Schematic diagram for explaining contour curves with trigonometric functions as basis functions Schematic diagram for explaining a contour curve satisfying Equation 1 Typical top view for demonstrating the aspect which utilizes a waveform uneven | corrugated for electrode tab formation Schematic plan view showing how the wave-shaped irregularities are changed (FIG. 11A: amplitude non-constant, FIG. 11B: wavelength non-constant) Plan view schematically showing the process aspect to be compared

Hereinafter, a method for manufacturing a secondary battery according to an embodiment of the present invention will be described in more detail. Although the description will be made with reference to the drawings as necessary, the various elements in the drawings are merely schematically and exemplarily shown for the understanding of the present invention, and the appearance and size ratio may be different from the actual ones. .

A “plan view (or plan view shape)” (for example, a plan view shape of an electrode precursor or an edge or an edge contour thereof) described directly or indirectly in the specification is a thickness of a metal sheet material or an electrode material. It is based on a sketch when taken from above or below along the direction. Here, the thickness direction of the metal sheet material / electrode material corresponds to the stacking direction of the electrodes (positive electrode / negative electrode) in the secondary battery.

Also, “vertical direction” and “horizontal direction” used directly or indirectly in the present specification correspond to the vertical direction and horizontal direction in the drawing, respectively. Unless otherwise specified, the same symbols or symbols indicate the same members or the same meaning. In a preferable aspect, it can be understood that the downward direction in the vertical direction (that is, the direction in which gravity works) corresponds to the “down direction” and the reverse direction corresponds to the “up direction”.

[Configuration of Secondary Battery Manufactured by the Present Invention]
In the manufacturing method of the present invention, a secondary battery is obtained. As used herein, “secondary battery” refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery obtained by the manufacturing method according to an embodiment of the present invention is not excessively bound by the name, and may include, for example, “electric storage device”. In addition, the term “electrode precursor” in the present specification broadly means that an electrode material layer is formed on a metal sheet material to be an electrode current collector, and contributes to the formation of a negative electrode or a positive electrode. Pointing to things. In particular, in a narrow sense, the “electrode precursor” in the present invention refers to an electrode body before a so-called “punching” for obtaining an electrode shape.

The secondary battery obtained by the production method of the present invention has an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are laminated. The positive electrode and the negative electrode are stacked via a separator to form an electrode constituent layer, and an electrode assembly in which at least one electrode constituent layer is laminated is enclosed in an outer package together with an electrolyte. The structure of the electrode assembly is not necessarily limited to a planar laminated structure. For example, an electrode unit (electrode constituent layer) including a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode is wound in a roll shape. You may have a winding structure (jelly roll type). For example, the electrode assembly 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.

The positive electrode is composed of at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, a positive electrode material layer is provided on at least one surface of the positive electrode current collector, and the positive electrode material layer contains a positive electrode active material as an electrode active material. For example, each of the plurality of positive electrodes in the electrode assembly may be provided with a positive electrode material layer on both surfaces of the positive electrode current collector, or may be provided with a positive electrode material layer only on one surface of the positive electrode current collector. . From the viewpoint of further increasing the capacity of the secondary battery, the positive electrode is preferably provided with a positive electrode material layer on both surfaces of the positive electrode current collector.

The negative electrode is composed of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, a negative electrode material layer is provided on at least one surface of the negative electrode current collector, and the negative electrode material layer contains a negative electrode active material as an electrode active material. For example, each of the plurality of negative electrodes in the electrode assembly may be provided with a negative electrode material layer on both surfaces of the negative electrode current collector, or may be provided with a negative electrode material layer only on one surface of the negative electrode current collector. . From the viewpoint of further increasing the capacity of the secondary battery, the negative electrode is preferably provided with a negative electrode material layer on both sides of the negative electrode current collector.

The electrode active materials contained in the positive electrode and the negative electrode, that is, the positive electrode active material and the negative electrode active material are materials directly involved in the transfer of electrons in the secondary battery, and are the main materials of the positive and negative electrodes 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. The positive electrode material layer and the negative electrode material layer are particularly preferably layers capable of occluding and releasing lithium ions. That is, it is preferable to be a nonaqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode through the nonaqueous electrolyte and the battery is charged and discharged. When lithium ions are involved in charge and discharge, the secondary battery obtained by the production method of the present invention corresponds to a so-called “lithium ion battery”, and the positive electrode and the negative electrode have layers capable of occluding and releasing lithium ions. .

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 more sufficient contact between the particles and shape retention. Furthermore, a conductive additive may be 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 more sufficient contact and shape retention between the particles, facilitating the transfer of electrons that promote the battery reaction. In order to make it, the conductive support agent may be contained 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 obtained by the production method of the present invention, such a lithium transition metal composite oxide is preferably contained as the 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. Although it is only an illustration to the last, in the secondary battery obtained with the manufacturing method of this invention, the positive electrode active material contained in a positive electrode material layer may be lithium cobaltate.

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. For example, the binder of the positive electrode material layer may be polyvinylidene fluoride, and the conductive additive of the positive electrode material layer may be carbon black. Although it is only an illustration to the last, the binder and conductive support agent of a positive electrode material layer may be 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. Although it is only an illustration to the last, in the secondary battery obtained with the manufacturing method of this invention, the negative electrode active material of a negative electrode material layer may be 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. For example, the binder contained in the negative electrode material layer may be 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.

For illustration purposes only, the negative electrode active material and the binder in the negative electrode material layer may be 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 used for the positive electrode and the negative electrode is a member provided from the viewpoint of preventing short circuit due to contact between the positive electrode and the negative electrode and maintaining 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 surface of the separator may be covered with an inorganic particle coat layer, an adhesive layer, or the like. The surface of the separator may have adhesiveness. In the present invention, the separator is not particularly limited by its name, and may be a solid electrolyte, a gel electrolyte, insulating inorganic particles or the like having the same function.

In the secondary battery obtained by the manufacturing method of the present invention, an electrode assembly including an electrode constituent layer including a positive electrode, a negative electrode, and a separator is enclosed in an exterior together with an electrolyte. When the positive electrode and the negative electrode have a layer capable of occluding and releasing lithium ions, the electrolyte is preferably a “non-aqueous” electrolyte such as an organic electrolyte or an organic solvent (that is, the electrolyte is a non-aqueous electrolyte). preferable). In the electrolyte, metal ions released from the electrodes (positive electrode and negative electrode) exist, and therefore, the electrolyte assists the movement of the metal ions in the battery reaction.

A non-aqueous electrolyte is an electrolyte containing a solvent and a solute. As a specific non-aqueous 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). Although it is only an illustration to the last, the combination of cyclic carbonate and chain carbonate may be used as a nonaqueous electrolyte, for example, you may use the mixture of ethylene carbonate and diethyl carbonate. In addition, as a specific nonaqueous electrolyte solute, for example, a Li salt such as LiPF ₆ and / or LiBF ₄ is preferably used.

The outer package of the secondary battery encloses the electrode assembly in which the electrode constituent layers including the positive electrode, the negative electrode, and the separator are laminated, but may be in a hard case form or a soft case form. Good. Specifically, the exterior body may be a hard case type corresponding to a so-called “metal can” or a soft case type corresponding to a “pouch” made of a so-called laminate film.

[Features of the production method of the present invention]
The production method of the present invention is characterized by a method for producing an electrode. In particular, it is characterized by the trimming of the electrode precursor from which the electrode is based. Specifically, as shown in FIG. 1, the production of at least one of the positive electrode and the negative electrode is performed by forming the electrode material layer 20 on the metal sheet material 10 serving as the electrode current collector to obtain the electrode precursor 30. And applying trimming to the electrode precursor 30 to at least partially cut off the edge 35 of the resulting electrode precursor 30 so that the edge 35 of the electrode precursor 30 forms a wave-like irregularity in the trimming. Then, the electrode precursor 30 is cut.

As can be seen from the plan view shown in the drawing, in the manufacturing method of the present invention, the electrode precursor edge is not simply trimmed into irregularities, but is trimmed so that the electrode precursor edges have “waveform” irregularities. Process. Such wavy irregularities are composed of “plurality of recesses” and “plurality of projections”, and therefore, the edge contour of the electrode precursor is generally curved or curved. In other words, in a preferred aspect, when viewed in a plan view of the electrode precursor, an edge portion of the electrode precursor (particularly, an edge contour along the longitudinal direction or the length of the electrode precursor) is angular or linear. Such as a straight portion extending in the longitudinal direction or a direction perpendicular thereto is not present.

The electrode precursor that is trimmed according to the present invention is suitable for a continuous manufacturing process. In particular, an electrode precursor having a curved uneven edge according to the present invention can be resistant to the electrode precursor being cut or torn by an external force received from a guide roll used for its conveyance. In other words, such inconveniences are avoided even under conditions where stress causing such breakage and / or tearing is likely to occur. Although the electrode precursor conveyed by the guide roll may be broken or torn due to the influence caused by the guide roll, such a possibility is reduced in one embodiment of the present invention. Preferably, the manufacturing method according to the embodiment of the present invention does not cause such “probability of tearing” and / or “probability of tearing”. Therefore, according to the present invention, the intended electrode precursor can be obtained more suitably, and as a result, a desired electrode can be obtained.

This is not limited by a specific theory, but is considered to be because the stress dispersion effect is more suitably achieved at the edge of the electrode precursor. In other words, in the present invention, the electrode precursor has an end profile (particularly, “longitudinal end” or “end along the transport direction” in the electrode precursor) having a “smoothly changing shape”. However, it is presumed that the effect of dispersing inconvenient stress that can occur in the electrode precursor due to the “smooth change” becomes more effective.

The manufacturing method of the present invention is characterized by the electrode precursor trimming process. First, a general method for manufacturing a secondary battery as a premise will be described in detail below.

In the manufacturing method of the secondary battery, after preparing and preparing the positive electrode, the negative electrode, the electrolytic solution, and the separator, respectively (may be procured from a commercial product if necessary), the secondary battery is integrated by combining them. Obtainable.

(Preparation of positive electrode)
For production of the positive electrode, a positive electrode material slurry is used. The positive electrode material slurry is an electrode material layer raw material containing at least a positive electrode active material and a binder. A positive electrode precursor, that is, an electrode precursor is obtained by applying the positive electrode material slurry to a metal sheet material (for example, aluminum foil) as a positive electrode current collector. If necessary, the positive electrode precursor may be subjected to rolling or pressing with a roll press. The metal sheet material used as the positive electrode current collector preferably has a long strip shape, and the positive electrode material slurry is applied to such a long metal sheet. It is preferable that the area to be applied is not applied to the entire periphery of the main surface of the long metal sheet, but to the peripheral portions in both width directions of the metal sheet material (especially at both end portions in the short direction of the metal sheet material). It is preferable not to apply the positive electrode material slurry). In one preferable aspect, the positive electrode material slurry is applied in a similar long shape so as to be slightly smaller than the long metal sheet material (particularly, the positive electrode material slurry is applied outside the edge region of the metal sheet material). preferable.

The formation of the positive electrode precursor, that is, the production of the electrode precursor can be continuously performed. That is, the electrode precursor can be obtained by a continuous manufacturing process. In such a case, the positive electrode material slurry is applied to the metal sheet material while feeding the metal sheet material in a predetermined direction from a sheet supply source wound in a roll shape. In other words, the metal sheet material is applied with the positive electrode material slurry while being moved and conveyed, whereby the electrode precursor is continuously produced. The metal sheet material or the electrode precursor obtained therefrom may undergo a drying process and / or a rolling process. A guide roll is used for conveyance of a metal sheet material, that is, conveyance of an electrode precursor. With such a guide roll, a tension is applied to the electrode precursor, and the electrode precursor is moved in a predetermined direction in that state.

The produced positive electrode precursor (especially a positive electrode precursor having a long strip shape) is stored, for example, in a roll shape as necessary, or is appropriately transported until it is used in the next step. Then, in the next step, cutting is performed to obtain a plurality of positive electrodes from the positive electrode precursor (in the case of being wound in a roll, cutting is performed after unfolding). For example, the positive electrode precursor is subjected to mechanical cutting to cut out the positive electrode from the positive electrode precursor (particularly, “part where the positive electrode material slurry is applied”). Although this is only an example, a cutting process such as a so-called “punching operation” may be performed. Here, when the electrode precursor is cut so that the region of the metal sheet material not provided with the electrode material layer is included in the cut shape, a tab can be provided on the electrode. In other words, a “positive electrode tab made of a metal sheet material” can be provided on the positive electrode by including a region where the metal sheet material not provided with the positive electrode material layer is exposed in the cut out shape to obtain the positive electrode. A plurality of desired positive electrodes can be obtained through the operations as described above.

(Preparation of negative electrode)
The production of the negative electrode is the same as the production of the positive electrode. In producing the negative electrode, a negative electrode material slurry is used. The negative electrode material slurry is an electrode material layer raw material containing at least a negative electrode active material and a binder. A negative electrode precursor, that is, an electrode precursor is obtained by applying such a negative electrode material slurry to a metal sheet material (for example, copper foil) as a negative electrode current collector. If necessary, the negative electrode precursor may be subjected to rolling or press treatment with a roll press. The metal sheet material used as the negative electrode current collector preferably has a long strip shape, and the negative electrode material slurry is applied to such a long metal sheet material. It is preferable that the area to be applied is not applied to the entire periphery of the main surface of the long metal sheet material but to the peripheral portions in both width directions of the metal sheet material (particularly, both end portions of the metal sheet material in the short direction) It is preferable not to apply the negative electrode material slurry to the above). In one preferred embodiment, the negative electrode material slurry is applied in the same long shape so as to be slightly smaller than the long metal sheet material (particularly, it is applied to other than the edge region of the metal sheet material). preferable. The production of the negative electrode precursor can also be carried out continuously as in the case of the positive electrode precursor. That is, the negative electrode precursor as an electrode precursor can be obtained by a continuous manufacturing process using a guide roll. The obtained negative electrode precursor (particularly, a long negative electrode precursor) is stored, for example, by being rolled into a roll as necessary, or is appropriately transported until it is used in the next step. Then, in the next step, cutting is performed to obtain a plurality of negative electrodes from the negative electrode precursor (in the case of being wound in a roll, cutting is performed after unfolding). For example, the negative electrode is cut out from the negative electrode precursor (particularly, “part where the negative electrode material slurry is applied”) by subjecting the negative electrode precursor to mechanical cutting. Although this is only an example, a so-called “punching operation” may be performed. Similarly to the positive electrode precursor, when the electrode precursor is cut so that the region of the metal sheet material not provided with the negative electrode material layer is included in the cut shape, a tab can be provided on the electrode. That is, a negative electrode tab made of a metal sheet material can be provided on the negative electrode by obtaining the negative electrode by including a region where the metal sheet material not provided with the negative electrode material layer is exposed in the cut shape. A plurality of desired negative electrodes can be obtained through the operations described above.

(Preparation of electrolyte)
An electrolyte that is responsible for ion transfer between the positive electrode and the negative electrode when the battery is used is prepared (in the case of a lithium ion battery, a nonaqueous electrolyte is particularly prepared). Therefore, a desired electrolyte is prepared by mixing raw materials to be such an electrolyte. In the manufacturing method of the present invention, the electrolyte may be a conventional electrolyte used in a conventional secondary battery, and therefore, the raw material may be the one conventionally used for manufacturing the secondary battery. .

(Preparation of separator)
In the production method of the present invention, the separator may be conventional, and therefore, a separator that is conventionally used as a secondary battery may be used.

The secondary battery can be obtained by integrally combining the positive electrode, the negative electrode, the electrolytic solution, and the separator prepared and prepared as described above. In particular, a secondary battery can be obtained by stacking a plurality of positive electrodes and negative electrodes through a separator to form an electrode assembly and enclosing the electrode assembly together with an electrolyte in an exterior body. The separator may be a laminate of sheets cut into sheets, or may be stacked in a ninety-nine shape and cut off excess. Furthermore, you may laminate | stack what packaged the electrode with the separator.

(Features of the present invention)
The present invention is characterized by the production of an electrode in the production of the secondary battery described above, and particularly by the trimming process of the electrode precursor. More specifically, in the production of at least one of the positive electrode and the negative electrode, the electrode precursor 30 is trimmed by trimming the edge 35 of the electrode precursor 30 at least partially. This is performed so that the edge 35 of the body 30 has a wave-like unevenness (see FIG. 1). Here, “at least partially cut off” is not intended to mean a mode in which a part of the edge is cut off (for example, a mode in which such a part is cut out a plurality of times), but the entire edge is cut off. In addition, a mode of cutting off (for example, a mode in which cutting processing is collectively performed on the entire edge) is also intended.

In the present invention, the edge of the electrode precursor is trimmed into “wave-like” irregularities, so that the edge contour of the electrode precursor as a whole is curved or curved. In one preferable aspect, in the plan view of the electrode precursor, all of the edge contours of the electrode precursor (particularly, the edge contours along the longitudinal direction or the length of the electrode precursor) are all curved or curved. Yes. In this way, the electrode precursor having the curved uneven (or curved uneven) edge can be more suitably subjected to the moving feed regardless of the external force that can be received from the guide roll in a continuous manufacturing process. In other words, the “wave-shaped unevenness” has the effect of more effectively dispersing the stress that can be brought from the guide roll to the electrode precursor (particularly the edge of the electrode precursor) by the feeding operation by the guide roll, Cutting and tearing from the edge of the electrode precursor is more effectively prevented.

Suppose that the edge of the electrode precursor is not “wavy uneven”. For example, assume that the edge contour of the electrode precursor includes a straight line portion. This may be a case where the edge contour includes a straight portion along the “longitudinal direction” or “conveying direction” of the electrode precursor, or “electrode” corresponding to the direction orthogonal to such a direction. A case where a straight line portion is included as an edge contour along the “short direction of the precursor” can be considered. As a more specific example of such an assumed aspect, a trimming (pre-trimming) edge cutting may include a linear cutting portion, or an edge cutting that is tabbed in advance (particularly the shape in plan view). In some cases, edge cutting is performed to perform tab cutting so as to have a quadrangular shape / rectangular shape. In such a case, it is difficult to effectively disperse the stress caused from the guide roll to the electrode precursor, and the edge of the “straight portion” is likely to be cut or torn. In particular, as shown in FIG. 2, the metal sheet material / electrode precursor is caused by the guide rolls 60 (“60A, 60B” and / or “60B, 60C”) separated from each other in the direction in which the electrode precursor moves. In the mode of moving in a bent state, a stress that easily causes a break or tear in the width direction of the metal sheet material 10 / electrode precursor 30 (that is, the short direction of the metal sheet material / electrode precursor) is likely to occur. Therefore, cutting and tearing easily occurs from the edge along the direction.

In other words, as shown in FIG. 2 ("separated lower installation guide roll 60A and upper installation guide roll 60B" and / or "separated upper installation guide roll 60B and lower installation guide roll 60C". In an aspect in which the electrode precursor 30 moves in a bent state), the linear edge of the metal sheet material / electrode precursor is taken as the starting point along the short direction of the metal sheet material 10 / electrode precursor 30. It can be said that breaks and tears are likely to occur. This is because the stress caused to the metal sheet material / electrode precursor due to the guide rolls spaced apart from each other cannot be effectively dispersed at the “straight edge”, and the stress tends to concentrate on a certain local portion. This is considered to be because. In this respect, in the present invention, local stress concentration can be reduced due to the fact that the edge of the electrode precursor has “wave-like unevenness”, and cutting and tearing from the edge is more effective. Can be prevented.

Here, in the present invention, the term “wave-shaped unevenness” broadly means that the edge of the electrode precursor has a curved shape or a curved shape including both “mountains” and “valleys”. ing. In a narrow sense, the plan view shape of the edge of the electrode precursor (in particular, the edge along the direction of movement of the metal sheet material) is “at least one curved peak” and “at least one curved valley”. It means that it has a curved or curved shape. Preferably, the wavy irregularities do not have angular or linear portions (particularly preferably, the wavy irregularities on the electrode precursor edge in a plan view are all curved or curved. It can be said to consist of:

As can be seen from the above, it is preferable that the “wave-shaped unevenness” includes a waved concave and a waved convex. That is, it is preferable that the contour shape at the edge of the electrode precursor is a wave-like unevenness including at least a waved concave and a waved convex. In particular, it is preferable that the edge 35 (that is, the longitudinal edge of the electrode precursor) along the moving feed direction of the metal sheet material is a wave-like unevenness including both a waved concave and a waved convex ( (See FIG. 3). As described above, when the edge contour of the electrode precursor is entirely curved / curved, the stress applied to the metal sheet material / electrode precursor is more easily dispersed by the guide roll used for conveyance, and from the edge Cutting and tearing can be prevented more effectively.

In the present invention, the “wave-like unevenness” is obtained by trimming. Such trimming corresponds to a cutting process performed on the edge of the electrode precursor. In trimming, a cutting process (that is, edge cutting) for appropriately cutting off the edge of the electrode precursor may be performed. In particular, it is preferable to perform trimming to cut the “edge along the transport direction” of the electrode precursor, that is, typically the “longitudinal edge”. This makes it possible to effectively provide a stress diffusion effect to an edge that is susceptible to inconvenient stress, particularly during moving feeding / conveying, and can more significantly prevent breakage and tearing from the edge.

) Appropriate cutting means may be used for trimming. For example, a mechanical cutting means such as a cutting blade may be used. Although it is only an example to the last, you may use a pair of cutting blade (rotation drive type cutting blade) comprised from the upper blade and lower blade which have a roll form. Trimming is performed by passing a sheet-shaped electrode precursor between the upper blade and the lower blade. Note that the trimming may be performed not only by such a cutting blade mode but also by using means such as a laser.

According to a preferred aspect, in the “wave-shaped unevenness”, the corrugated concave and the corrugated convex adjacent to each other share a part. That is, the contour shape of the edge of the trimmed electrode precursor has a wave-like unevenness, and a part of “one of the waved concave and the waved convex” can constitute the other part of them. This will be described with reference to FIG. A part of the corrugated concave constitutes a part of the corrugated convex, and vice versa, a part of the corrugated convex constitutes a part of the corrugated concave. In such an embodiment, the edge contour of the electrode precursor may be a continuous curve / curve as a whole due to the curved irregularities, and therefore, the curve or the curve that changes integrally along the direction of the edge or A curve line is obtained. Therefore, the stress brought from the guide roll to the metal sheet material / electrode precursor becomes easier to disperse, and breakage and tearing from the edge can be more effectively prevented.

In the present invention, it is preferable that most of the edges in the transport direction of the electrode precursor (preferably substantially all of the edges in the transport direction) are subjected to the trimming process. This means that all the edges of the trimmed electrode precursor (especially the long edges of the electrode precursor) are wavyly contoured, and therefore such trimmed edges However, it does not preferably include an angular portion or a straight portion (particularly, a straight portion along the conveying direction or a direction perpendicular thereto), and all of the trimming edges are curved or curved. It can be said that it preferably consists of That is, it is preferable that “curved unevenness” occupies most of the longitudinal edges of the electrode precursor (preferably, all of the edges that will pass through the guide roll). Thereby, the electrode precursor continuously conveyed by the guide roll is in a state in which cutting and tearing from the longitudinal edge corresponding to the conveyance direction edge is effectively prevented.

In the trimming according to a preferred aspect, only the electrode material non-formation region of the metal sheet material not provided with the electrode material layer is cut off. That is, as shown in FIG. 5A, the electrode material layer 20 is not included in the cut-off portion removed by trimming. In the formation of the electrode precursor, the electrode is formed in a central region other than the peripheral region of the metal sheet material (more specifically, other than the end portion in the short direction of the metal sheet material, preferably other than the both ends in plan view). When the material layer 20 is formed, the trimming process is performed only on the peripheral area. According to such an aspect, as shown in FIG. 5A, the innermost point of the corrugated concave portion of the “wave-shaped concave / convex” is positioned outside the edge of the electrode material layer in plan view.

In the aspect in which trimming is performed only on the “polar material non-formation region”, the trimming cutting accuracy can be improved because the cutting is performed on a single metal sheet material. In other words, in this aspect, the contour curve of the edge of the electrode precursor can be a more accurate curve, so that the stress caused from the guide roll to the metal sheet material / electrode precursor is more easily dispersed and cut from the edge. -Tearing can be prevented more effectively.

In trimming according to another preferred embodiment, not only the electrode material non-formation region of the metal sheet material not provided with the electrode material layer 20 but also the electrode material formation region provided with the electrode material layer 20 is partially applied. Cut off to include. That is, as shown in FIG. 5B, the electrode material layer 20 is partially included in the cut-off portion removed by trimming. In the formation of the electrode precursor, the electrode material layer is formed in the central region other than the peripheral region of the metal sheet material, and the trimming process is performed not only on the peripheral region but also on the central region. According to such an aspect, as shown in FIG. 5 (B), the innermost point of the wave-shaped concave portion of the “wave-shaped unevenness” in a plan view is located inside the electrode material layer edge (preferably, (It will be located slightly inside the electrode material layer edge).

In the aspect of performing trimming including not only the “polar material non-formation region” but also a part of the “polar material formation region”, the finally obtained tabbed electrode is obtained as “an electrode having a higher proportion of the polar material layer”. This contributes to more favorable battery production in terms of battery capacity. That is, in this aspect, not only the electrode manufacturing process that can prevent the cutting and tearing of the edge of the electrode precursor, but also an advantageous effect can be achieved not only in terms of the characteristics of the finally manufactured secondary battery.

In the present invention, the “wave-like unevenness” may form a periodic curve. That is, when the trimming process is performed so that the edge contour of the electrode precursor has a curved uneven curve, the curve may be a regular curve. For example, the wavelength dimension may be substantially constant and / or the amplitude dimension may be constant for a wave curve of an edge contour due to a wave-shaped unevenness. From another perspective, it can be said that all the recesses and / or all the projections in the “edge contour has a wave-like unevenness” may have substantially the same shape. In such an aspect, since the edge contour of the electrode precursor can be equalized as a whole due to the curved irregularities, the stress caused from the guide roll to the metal sheet material / electrode precursor is more easily dispersed, and from the edge Cutting and tearing can be more effectively prevented.

In a preferred embodiment, the wavy unevenness forms a “curve that does not include geometric singularities”. That is, when the trimming process is performed so that the edge contour of the electrode precursor has a curve due to the wavy irregularities, it is preferable that the function representing the curve does not have a singular point. The term “geometric singularity” as used herein means, in a broad sense, a place where the target curve can show an abnormal form as compared to the general curve. In other words, “geometric singularity” means a point that is not given by the smooth embedding of the parameters for the curve in question. In a narrow sense, the “geometric singularity” in the present invention is the mathematics handbook (published on April 5, 1994, 1st edition, 5th edition, publisher: Morikita Publishing Co., Ltd., supervisor: Kentaro Yano, editor) : Toshio Miyamoto, publisher: Atsushi Morikita) means “singularity” described on page 583.

In the aspect of “curved irregularities that do not include geometric singularities”, the curve of the edge contour of the electrode precursor becomes smoother as a whole, so that from the guide roll to the metal sheet material / electrode precursor. The resulting stress can be more easily dispersed, and cutting and tearing from the edge can be prevented more effectively.

Although it is merely an exemplary category, the contour curve of the edge of the trimmed electrode precursor is a point (point), jump point, corner point, isolated point, double point, self, which is a geometric singular point It may be a curve that does not have a contact point and / or a triple point. Such a contour curve may be a regular curve. Preferably, the contour curve of the edge of the electrode precursor does not have a point (a cusp), a jump point, a corner point, an isolated point, a double point, a self-contact point, or a triple point as geometric singular points. In addition, trimming processing is performed so as to obtain a regular curve. The terms “point (point)”, “isolation point”, “two points”, “self-contact point”, “three points”, “leap point”, “corner point” and “regular” It essentially refers to what is described in the "Mathematical Handbook" above. 6A to 6C are schematic views in which the edge contour of the electrode precursor has geometric singularities in order to understand the aspect of “curved irregularities do not include geometric singularities”. Examples are shown in FIGS. 7A to 7D.

Further, regarding the contour curve of the edge of the trimmed electrode precursor, when the “longitudinal direction” or “conveying direction” of the electrode precursor is the x axis and the direction orthogonal thereto is the y axis, the contour curve is y = Sin ( nx) + Cos (mx) (−π ≦ x ≦ π, 0 <n, 0 <m, y / x ≦ 1) may be a curve having a basis function (see FIG. 8). In this way, the contour curve with trigonometric functions as a basis function also has the effect of further distributing the stress caused from the guide roll to the metal sheet material / electrode precursor, and more effectively prevents breakage and tearing from the edge. Is done. Furthermore, it may be a contour curve as shown in FIG. That is, with respect to the contour curve of the edge of the trimmed electrode precursor, when the “longitudinal direction” or “transport direction” of the electrode precursor is the x axis and the direction orthogonal thereto is the y axis, the contour curve is expressed by the following formula ( The curve may satisfy Equation 1). Such a contour curve can also have an effect of further dispersing the stress caused from the guide roll to the metal sheet material / electrode precursor.

In the manufacturing method of the present invention, “wave-like unevenness” can be used for electrode tab formation. More specifically, the trimmed electrode precursor 30 may be cut out so that the tab 45 is positioned in the “wave-convex” region of the wave-like unevenness, whereby the “electrode provided with the tab” Can be obtained more suitably (see FIG. 10). In other words, as shown in FIG. 10, when cutting is performed by including a region (electrode material non-forming region) of the metal sheet material 10 where the electrode material layer 20 is not provided in the cut shape, the pole included in the cut shape 40. The material non-formation region is particularly located on the corrugation. As a result, at least a part of the “convex convex” constitutes the tab 45, and a “tabbed electrode” can be obtained more suitably. As described above, in the aspect of utilizing the “waved unevenness” for forming the electrode tab, not only in terms of the electrode manufacturing process in which cutting and tearing of the edge of the electrode precursor can be prevented, but also in terms of the configuration of the electrode to be manufactured. It can be said that an advantageous effect can be achieved.

In the present specification, the term “tab” means an external terminal element used for electrical connection with the outside in a broad sense, and in a narrow sense, a part of a positive or negative current collector. In particular, an electrode active material (positive electrode material / negative electrode material) is not provided, and it means an external terminal element having a form protruding from the positive electrode or the negative electrode in the electrode assembly.

As can be seen from FIG. 10, in the embodiment in which the wavy unevenness is used for forming the electrode tab, the electrode may be cut out so that the contour of the tip of the tab forms the same curve (planar curve) as the “wave shape convex”. . That is, in such an embodiment, the tab is a tab having a curved or curved contour (preferably a curved or curved contour similar to or similar to a “convex portion” in the wave-like unevenness of the long edge of the electrode precursor). Preferably formed.

As mentioned above, although the embodiment of the present invention has been described, a typical example is merely illustrated. Therefore, those skilled in the art will easily understand that the present invention is not limited to this, and various modes are conceivable.

For example, although the description has been given of the aspect in which the amplitude of the wave curve of the edge contour caused by the wavy irregularities is substantially constant and the wavelength is also constant, the present invention is not particularly limited to this. As shown in FIG. 11A, an aspect in which the amplitude of the wave curve is not constant may be employed (in the aspect illustrated, an aspect in which the change in amplitude is periodic is illustrated). Moreover, as shown in FIG. 11 (B), the wavelength of the wave curve of the edge contour resulting from the wave-shaped unevenness may be a mode in which the wavelength changes periodically in the mode shown. The mode which is shown is illustrated. Even in such an embodiment, since the stress caused from the guide roll to the metal sheet material / electrode precursor is dispersed, it is possible to effectively prevent breakage and tear from the edge.

The secondary battery obtained by the manufacturing method according to an embodiment of the present invention can be used in various fields where power storage is assumed. For illustration purposes only, secondary batteries are used in the electrical / information / communication field where mobile devices are used (for example, mobile phones, smart watches, smartphones, laptop computers, digital cameras, activity meters, arm computers and electronic devices). Paper and other mobile devices), home / small industrial applications (eg, power tools, golf carts, home / care / industrial robots), large industrial applications (eg, forklifts, elevators, bay harbor cranes) ), Transportation systems (for example, hybrid vehicles, electric vehicles, buses, trains, electric assist bicycles, electric motorcycles, etc.), power system applications (for example, various power generation, road conditioners, smart grids, general home-installed energy storage systems) Field), IoT field, and space / Sea applications (for example, spacecraft, areas such as submersible research vessel) can be used, such as in.

DESCRIPTION OF SYMBOLS 10 Metal sheet material 20 Electrode material layer 30 Electrode precursor 35 Edge of electrode precursor 40 Cut shape of electrode / electrode to be cut (for example, “non-rectangular” electrode)
45 tabs

Claims

A method for manufacturing a secondary battery, comprising:
Production of at least one of a positive electrode and a negative electrode
Forming an electrode material layer on a metal sheet material to be an electrode current collector to obtain an electrode precursor, and applying trimming to the electrode precursor to at least partially cut off an edge of the electrode precursor. ,
A method for manufacturing a secondary battery, wherein the trimming is performed so that the edge of the electrode precursor has a wave-like unevenness.
The method for manufacturing a secondary battery according to claim 1, wherein the wave-like unevenness includes both a waved concave and a waved convex.
3. The method of manufacturing a secondary battery according to claim 1, wherein the corrugated concave and the convex corrugated adjacent to each other in the wave-shaped irregularities share a part with each other.
The method for manufacturing a secondary battery according to any one of claims 1 to 3, wherein the undulating unevenness forms a periodic curve.
The method for manufacturing a secondary battery according to any one of claims 1 to 4, wherein the undulating unevenness forms a curve that does not include a geometric singular point.
6. The method of manufacturing a secondary battery according to claim 1, wherein, in the trimming, only an electrode material non-formation region of the metal sheet material on which the electrode material layer is not provided is cut off.
In the trimming, the metal sheet material not provided with the electrode material layer is cut off so as to partially include not only the electrode material non-formation region of the metal sheet material but also the electrode material layer provided with the electrode material layer. Item 6. The method for producing a secondary battery according to any one of Items 1 to 5.
In the formation of the electrode precursor, the metal sheet material is moved using a guide roll,
The method of manufacturing a secondary battery according to any one of claims 1 to 7, wherein the metal sheet material moves in a bent state due to the guide rolls spaced apart from each other in the movement direction.
Further comprising cutting out from the electrode precursor to form the electrode;
The electrode precursor is cut out so that a region of the metal sheet material not provided with the electrode material layer is included in the cut shape, and a tab is provided on the electrode. A method for manufacturing a secondary battery.
The method for manufacturing a secondary battery according to any one of claims 1 to 9, wherein the trimming is performed on a longitudinal edge of the electrode precursor.
The method for producing a secondary battery according to any one of claims 1 to 10, wherein the positive electrode and the negative electrode have a layer capable of inserting and extracting lithium ions.