WO2018155175A1

WO2018155175A1 - Secondary battery production method

Info

Publication number: WO2018155175A1
Application number: PCT/JP2018/004078
Authority: WO
Inventors: 佳介島田; 徹川合; 昌史樋口
Original assignee: 株式会社村田製作所
Priority date: 2017-02-23
Filing date: 2018-02-06
Publication date: 2018-08-30

Abstract

Provided is a secondary battery production method which is capable of more suitably coping with winding misalignment. The secondary battery production method according to the present invention is for producing a secondary battery having a wound electrode body comprising a positive electrode and a negative electrode, wherein the wound electrode body is formed by winding an electrode precursor laminated body comprising a laminate formed by stacking a positive electrode precursor and a negative electrode precursor with a separator interposed therebetween. During winding, the electrode precursor laminated body is subjected to pressing, and a pressure heater is used for that purpose.

Description

Manufacturing method of secondary battery

The present invention relates to a method for manufacturing a secondary battery. In particular, it is related with the manufacturing method of the secondary battery which has an electrode winding body comprised from 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. A secondary battery has 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

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 a secondary battery, an electrode assembly is formed by laminating a positive electrode, a negative electrode, and an electrode constituent layer including a separator between them, but if the lamination is undesirably shifted, the secondary battery cannot be improved. End up. For example, when the “winding deviation” increases between the positive electrode and the negative electrode, lithium is likely to be deposited from the negative electrode in the secondary battery. Lithium deposition may cause a larger capacity reduction with repeated charging and discharging during battery use, and may cause heat generation and / or ignition due to overcharging. That is, the winding deviation in the electrode assembly is one of important design items to be considered in the production of the secondary battery.

Winding deviation becomes more severe in the production of a secondary battery having a winding structure, particularly when the secondary battery has a unique shape. Specifically, when manufacturing a secondary battery having a unique shape as an external shape (for example, when manufacturing a “non-rectangular” or “step-shaped” secondary battery), the shape of the electrode constituent layers constituting the battery Since (especially the shape in plan view) becomes finer, the allowable range for winding deviation becomes narrow.

The present invention has been made in view of such problems. That is, the main object of the present invention is to provide a method of manufacturing a secondary battery that can be more appropriately dealt with in terms of winding deviation.

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 present invention has achieved the “invention of a method for manufacturing a secondary battery” in which the above-described main object is achieved.

The manufacturing method according to the present invention includes:
A method for producing a secondary battery having an electrode winding body composed of a positive electrode and a negative electrode,
An electrode precursor is formed by winding an electrode precursor laminate composed of a laminate of a positive electrode precursor and a negative electrode precursor via a separator,
In such winding, the electrode precursor laminate is subjected to pressing, and a pressing heater is used for the pressing.

The method for manufacturing a secondary battery according to the present invention can suitably cope with winding deviation. Specifically, since a “pressing heater” is used for pressing the electrode precursor laminate during winding, interlayer bonding in the electrode precursor laminate is more suitable. That is, since both the “pressing action” and the “warming action” are given to the electrode precursor laminate by the press heater, the electrode material of the obtained electrode winding body and the separator are more suitably joined. Winding deviation is prevented more effectively.

Due to the prevention of winding deviation, the present invention can improve the quality of the secondary battery more suitably. In particular, even in the manufacture of a “uniquely shaped secondary battery” that has a narrower allowable range for winding deviation, the present invention can improve the quality of the product more suitably.

Schematic cross-sectional view exemplarily showing the concept of electrode configuration layers Typical sectional drawing which showed the process aspect relevant to the manufacturing method which concerns on one Embodiment of this invention. Another typical sectional view showing a process mode relevant to a manufacturing method concerning one embodiment of the present invention The typical perspective view which showed the process aspect relevant to the manufacturing method which concerns on one Embodiment of this invention. Cross-sectional view schematically showing a mode of being pressed more widely Sectional drawing which showed the aspect which performs a pressure heat treatment from the winding start of an electrode precursor laminated body typically Sectional drawing which showed the aspect which performs a pressure heat treatment sequentially for every rotation Schematic showing how to obtain a “non-rectangular” electrode winding body Schematic showing how to obtain a “step-shaped” wound electrode body Schematic diagram for explaining “non-rectangular shape”

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 purpose of understanding the present invention, and the appearance and size ratio are different from the actual ones. obtain.

The direction of “thickness” described directly or indirectly in the present specification is based on the stacking direction of the electrode materials constituting the secondary battery. For example, in the case of a “secondary battery having a plate-like thickness” such as a flat battery, the direction of “thickness” corresponds to the thickness direction of the secondary battery. The “plan view” used in the present specification is based on a sketch when the object is viewed from the upper side or the lower side along the thickness direction. Further, in the present specification, the “sectional view” is based on a virtual cross section of an object obtained by cutting along the thickness direction of the secondary battery.

Furthermore, “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 / parts 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”.

[Basic configuration of secondary battery]
In the present invention, a secondary battery is provided. The “secondary battery” in the present specification refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery obtained by the manufacturing method of the present invention is not excessively bound by its name, and for example, “electric storage device” can also be included in the object.

A secondary battery having a winding structure has a structure in which an electrode material and a separator are wound. Specifically, such a secondary battery has an electrode winding body in which an electrode constituent layer including a positive electrode, a negative electrode, and a separator is laminated. FIG. 1 illustrates the concept of an electrode winding body. As shown in the drawing, the positive electrode 1 and the negative electrode 2 overlap with each other via a separator 3 to form an electrode constituent layer 5, and the electrode constituent layer 5 is wound to form an electrode winding body. In a secondary battery, such an electrode winding body is enclosed in an exterior body together with an electrolyte (for example, a nonaqueous electrolyte).

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 positive electrodes in the electrode winding body 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. .

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 negative electrodes in the electrode winding body 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. .

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 charging / discharging, the secondary battery according to 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 also composed of, for example, a granular material, and it is preferable that a binder is included for more sufficient contact between the particles and shape retention, and transmission of electrons that promote the battery reaction. In order to make smooth, 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 auxiliary agent 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 according to the present invention, an electrode winding body including an electrode constituent layer including at least a positive electrode, a negative electrode, and a separator is enclosed in an outer package 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 non-aqueous electrolyte, for example, the mixture of ethylene carbonate and diethyl carbonate is used. 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 wraps around the electrode winding body in which the electrode constituent layers including the positive electrode, the negative electrode, and the separator are laminated, but may be in the form of a hard case or in the form of a soft case. Also 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.

[Production method of the present invention]
The production method of the present invention is characterized by a method for producing an electrode winding body. In particular, it has a feature in a winding method when obtaining an electrode precursor laminate comprising a laminate of a positive electrode precursor and a negative electrode precursor via a separator. Specifically, as shown in FIGS. 2 to 4, the electrode precursor laminate 10 is pressed during winding, and a pressing heater 50 is used for the pressing.

In the manufacturing method of the present invention, when the electrode winding body is obtained by a winding operation, the wound object is pressed with a pressure heater so that an external load is applied to the wound object at the time of winding. Since the pressing heater is not only a pressing source but also a heating source, not only an external load can be applied but also heat can be supplied to the wound object through the pressing of the pressing heater. Thus, when the electrode precursor laminated body which consists of a lamination | stacking of the positive electrode precursor and negative electrode precursor through a separator is wound, the press process of a press heater is performed.

In the present specification, the “positive electrode precursor” refers to the positive electrode before the electrode winding body is obtained, and is therefore at least composed of a positive electrode material layer and a positive electrode current collector. Similarly, in the present specification, the “negative electrode precursor” refers to the negative electrode before the electrode winding body is obtained, and is therefore at least composed of the negative electrode material layer and the negative electrode current collector. .

In a preferred aspect of the present invention, a pressure heat treatment is performed in which the electrode precursor laminate is subjected to both pressing and heating by pressing with a pressing heater. More specifically, the electrode precursor laminate is pressed from the outside to the inside (core side) due to the “pressing element” of the pressing heater, and the electrode due to the “heater element” of the pressing heater. Heat is transferred to the precursor laminate from the outside to the inside (core side). That is, heating is performed while pressing the electrode precursor laminate with a press heater.

Thus, when a pressure heater is used for the electrode precursor laminated body at the time of winding, interlayer bonding of the electrode precursor laminated body becomes more suitable. That is, when both the “pressing action” and the “heating action” are applied to the electrode precursor laminate with a press heater, the “between the separator and the cathode precursor” and the “separator and anode precursor” forming the electrode precursor laminate Are more suitably joined (eg, they are more fully joined together). This means that the electrode material of the electrode winding body and the separator are more suitably joined, so that “winding deviation” is more effectively prevented.

The effect of preventing the winding slippage can be more prominent when an adhesive layer is provided on the electrode precursor laminate. That is, both “pressing action” and “heating action” by the pressing heater effectively act on the adhesive layer of the electrode precursor laminate, and winding deviation can be prevented more effectively. Therefore, in the production method of the present invention, it is preferable to use a laminate including an adhesive layer as the electrode precursor laminate. In such a laminate, an adhesive layer is preferably positioned between at least one of the positive electrode precursor and the negative electrode precursor and the separator. That is, an adhesive layer may be provided between one of the positive electrode precursor and the negative electrode precursor and the separator, or both between the positive electrode precursor and the separator and between the negative electrode precursor and the separator. An adhesive layer may be provided.

When the adhesive layer is positioned between at least one of the positive electrode precursor and the negative electrode precursor and the separator in the electrode precursor laminate, “between the separator and the positive electrode precursor” and “between the separator and the negative electrode precursor” At least one of these can be more suitably joined, and winding slippage can be prevented more effectively. Particularly preferred is to obtain an electrode precursor laminate in which an adhesive layer is provided between each of the positive electrode precursor and the negative electrode precursor and the separator, whereby “between the separator and the positive electrode precursor” and “separator And “a negative electrode precursor” are more suitably bonded.

The adhesive layer may be provided in advance on the main surface of the separator and / or the electrode material layer (positive electrode material layer / negative electrode material layer). In a preferred embodiment, the adhesive layer is provided in advance on the main surface of the separator. Such an adhesive layer may be provided on at least one of the two main surfaces of the separator. For example, an adhesive layer may be provided in advance on both main surfaces of the separator, whereby an electrode precursor laminate in which the adhesive layer is positioned between each of the positive electrode precursor and the negative electrode precursor and the separator. Can be obtained more suitably.

The adhesive itself constituting the adhesive layer in the present invention may be used for a conventional secondary battery. Although it is only an example to the last, the adhesive bond layer has an insulation characteristic, for example, may comprise polyvinylidene fluoride (PVDF) or an acrylic resin (such as alumina as necessary). An inorganic filler may be added). If the emphasis is particularly placed on the viewpoint that the “heating action” of the pressure heater becomes more effective, the adhesive layer preferably contains a so-called “hot melt type” adhesive. In the production method of the present invention, both the “pressing action” and the “warming action” of the pressure heater can be acted to bring out the adhesive effect of the adhesive layer more effectively. It can be provided thinner (that is, it can be an adhesive layer having a smaller thickness, which contributes to downsizing of the battery). That is, an adhesive layer (that is, an adhesive film layer) as a thin layer can be positioned between at least one of the positive electrode precursor and the negative electrode precursor and the separator.

Here, the “pressing heater” in the present invention refers to a heater that can apply pressure in a broad sense, and in a narrow sense, “pressing action” and “warming” against a wound object. It refers to a battery manufacturing tool capable of providing both of “operation”. Such a pressure heater can give both “pressing action” and “heating action” to the electrode precursor laminate by contacting the wound electrode precursor laminate so as to press from the outside. .

The pressing heater 50 may have a paired form as shown in FIGS. 3 and 4. That is, the pressing heater 50 used in the manufacturing method of the present invention may be configured by two sub pressing heaters (50A, 50B) arranged to face each other so as to form a pair. Thereby, an electrode precursor laminated body can be pressed from two outer sides which the electrode precursor laminated body at the time of winding opposes. For example, the electrode precursor laminate may be flattened by the pressing action of the pressing heater 50. That is, the three-dimensional shape (overall three-dimensional shape) of the electrode winding body may be flattened by pressing from the outside to the opposing main surfaces of the electrode precursor laminate. In the case of the “flat” electrode winding body, the external shape of the finally obtained secondary battery can be “flat”, that is, “plate” or “thin plate”. Therefore, the “flat shape” is at least preferable for a restricted battery installation space in a housing such as a mobile device. In the present specification, the term “flat” means that at least the thickness dimension is smaller than the other dimensions (particularly the dimension forming a plan view shape) in the electrode winding body or the secondary battery, Means that the overall appearance of the electrode winding body or battery is “plate-like” or “thin plate-like”.

The pressure heater used in the manufacturing method of the present invention preferably has a drive mechanism (drive source) to provide a “pressing action”. In particular, it is preferable that the body portion of the pressure heater can be moved and driven toward the electrode precursor laminate so that pressure can be applied to the electrode precursor laminate at the time of winding. Further, the pressure heater preferably has a heat source to provide a “warming action”. In particular, it is preferable that the body 10 (for example, a cylindrical body) of the pressure heater that is in contact with the electrode precursor laminate at the time of winding can be heated to a temperature higher than that of the electrode precursor laminate. Speaking of the heat source, the press heater may be provided with a coil heater or a band heater in its body, or a high-temperature medium such as high-temperature water or steam is supplied into the inside of the body of the press heater. It may be.

As shown in FIGS. 3 and 4, in the manufacturing method of the present invention, the winding of the electrode precursor laminate itself may be performed using a winding core 70. As illustrated, the separator 3 ′, the positive electrode precursor 1 ′, and the negative electrode precursor 2 ′ are provided to the winding core 70, respectively, while the separator 3 ′, the positive electrode precursor 1 ′, and the negative electrode are rotated with respect to the rotating winding core 70. The electrode precursor laminate 10 can be formed while rotating by causing the precursors 2 'to be wound around each other. When the winding core 70 is used, it is preferable that the pressure heaters 50 (50A, 50B) are arranged so as to form a pair with the winding core 70 interposed therebetween. Thereby, an electrode precursor laminated body can be pressed from both the opposing outer sides, while an electrode precursor laminated body is wound. As shown in the drawing, the winding core 70 may have, for example, a flat plate shape, and in one aspect, may include two flat plate members.

When winding is performed using a winding core, the electrode precursor laminate 10 is sandwiched between the inner winding core 70 and the outer pressing heater 50 (50A, 50B) as shown in FIGS. It is preferable to perform a pressure heat treatment throughout. When the winding core is a metal core (that is, when the winding core has heat transfer properties), a heat transfer path is suitably formed between the winding core and the heater. The electrode precursor laminate is heated more efficiently. Thus, in a suitable aspect, winding is performed using a metal winding core (for example, a metal core having a rectangular cross section).

In a preferred aspect, the pressure heater has a roller form. For example, the form of the pressure heater 50 used in the manufacturing method of the present invention may be a pair of rollers as shown in FIG. 4 (for example, the pressure heater is composed of a pair of cylindrical sub-rollers. May be) That is, this mode corresponds to the pressing heater being a roller heater. The electrode precursor laminate is pressed from the outside by such a roller heater, and the electrode precursor laminate is more suitably subjected to pressure heat treatment.

In the case of the roller form, the pressing heater is energized while rotating on the outer surface of the wound electrode precursor laminate, so that the outer surfaces of the electrode precursor laminates facing each other are widely pressed (see FIG. 5). ). In other words, due to the interaction between the “winding electrode precursor laminate” and the “rotating press heater”, the outer surface of the electrode precursor laminate is pressed extensively and entirely. A roller body, for example, a cylindrical roller body, may be configured to be able to be driven and moved in a wide and narrow manner with respect to each other (that is, a gap formed between the sub roller 50A and the sub roller 50B). The roller body is preferably made of a rigid material such as metal. Moreover, you may give peelability processing to the trunk | drum surface of a roller so that an inadequate adhesion | attachment may not arise between a roller and a separator at the time of pressurization heat processing.

In such a manner that the outer surface of the electrode precursor laminate is pressed extensively as described above, it becomes easy to produce a flat electrode winding body. In other words, the electrode precursor laminate is sandwiched between the core (a core having a flat main surface) and the roller and pressed on the main surface of the core, thereby opposing both mains of the electrode precursor laminate. The surface is flattened, and the three-dimensional shape of the electrode winding body can be made “flat”. In this aspect, it can be said that the range in which the interlayer is fixed by the pressure heater having the roller form corresponds to the straight portion of the electrode winding body. By going through such a winding process, the final shape of the secondary battery can be made into a “plate” or “thin plate”, and constrained battery installation in a housing such as a mobile device A battery favorable for space can be obtained.

In a preferred embodiment, pressure heat treatment is performed from the beginning of winding of the electrode precursor laminate. That is, as shown in FIG. 6, the electrode precursor laminate is subjected to both pressurization and heating from the start point of the winding process of the electrode precursor laminate. This means that the pressure heat treatment is performed from the first bent portion of the electrode precursor laminate. By performing such pressure heat treatment, both the “pressing action” and the “warming action” are applied to the entire wound body obtained (when viewed in cross-section, from the center inside to the surface outside). Can be more effective.

In the present invention, “winding start” means “polymerization of positive electrode precursor layer and separator”, “polymerization of negative electrode precursor layer and separator” and / or “positive electrode precursor layer, separator and negative electrode precursor”. Substantially means the point in time when the “polymerization with the layer” is first made. If it catches simply, "winding start" means the time of winding in which the winding center part of an electrode winding body will be formed.

In the production method of the present invention, the pressure heat treatment started from the beginning of winding may be performed until the end of winding of the electrode precursor laminate. That is, the pressure heat treatment may be continuously performed during the winding process of the electrode precursor laminate.

More preferably, pressurization heat treatment is sequentially performed so that the electrode precursor laminate is subjected to both pressurization and heating in each rotation of winding. That is, pressing and heating are performed at any rotation in winding (that is, for each rotation) (see FIG. 7). As can be seen from the embodiment shown in FIG. 7, “the electrode precursor laminate is subjected to pressure heat treatment in each rotation of winding” simply refers to any rotation of the electrode precursor laminate. It means a mode in which both opposing surfaces of the electrode precursor laminate are pressed.

When the pressure heat treatment is performed sequentially and continuously in each rotation of the winding, the pressure heat treatment is uniformly applied to the entire electrode winding body (particularly, the entire electrode winding body in a cross-sectional view). be able to. In other words, the “pressing action” and the “heating action” can be applied evenly not only to the surface side of the electrode winding body but also to a deep portion near the winding center. This means that the interlayer bonding is more uniform in the entire electrode winding body, and winding deviation can be prevented more effectively. In other words, the bonding state of each layer of the electrode winding body can be made substantially more uniform by sequential pressure heat treatment in each winding.

In the production method of the present invention, “winding deviation” is more effectively prevented. Specifically, “between the separator and the positive electrode precursor” and “separator and negative electrode precursor” forming the electrode precursor laminate are provided. The “between” is more preferably joined, and winding slippage can be more effectively prevented. Here, the prevention of winding deviation is particularly effective when a secondary battery having a unique shape is manufactured. For example, when obtaining an electrode winding body having an unusual shape such as “non-rectangular shape” or “step shape” as an external shape (that is, when manufacturing a secondary battery having such an unusual shape), an electrode constituting the battery Since the shape of the constituent layer (the shape in plan view) becomes fine, the allowable range for winding deviation is generally narrow and severe. In this respect, since the press heater is used in the present invention, even such severe lamination conditions / winding conditions can be suitably dealt with, and such a narrow allowable range can be dealt with.

For example, as shown in FIG. 8, when obtaining the electrode winding body 100 having a non-rectangular shape in plan view, the positive electrode precursor 1 ′, the negative electrode precursor 2 ′, and the separator 3 ′ before winding are in plan view. It has a “comb shape”. Similarly, as shown in FIG. 9, even when the electrode winding body 100 including a step shape as a three-dimensional outer shape is obtained, the positive electrode precursor 1 ′, the negative electrode precursor 2 ′, and the separator 3 ′ before winding are planar. It has a “comb shape” in view. Since both are “comb shape”, the electrode precursor laminate 10 has a narrow portion 11 and a wide portion 12 in a plan view, and is a relatively refined shape. As used herein, the “narrow part” means a local part of the electrode precursor laminate having a relatively reduced width dimension in plan view, while the “wide part” means a relatively width dimension in plan view. Means the local portion of the electrode precursor laminate (where the “width dimension” is gradually reduced due to winding, as can be seen from the plan view shown in the figure. Substantially means the dimension of the electrode precursor laminate in the direction perpendicular to the body dimensions). That is, the positive electrode precursor 1 ′, the negative electrode precursor 2 ′, and the separator 3 ′ before winding are not constant in width, and have a locally reduced form or a locally increased form. ing. Preferably, in each of the positive electrode precursor 1 ′, the negative electrode precursor 2 ′, and the separator 3 ′, a plurality of “narrow portions” and “wide portions” are provided, and “narrow portions” and “wide portions” are provided. It is preferable that they are alternately continuous. In a preferable aspect, in each of the positive electrode precursor 1 ′, the negative electrode precursor 2 ′, and the separator 3 ′, a plurality of “narrow portions” have substantially the same shape and the same size as each other. The “wide portions” of each have substantially the same shape and size. In other words, the positive electrode precursor 1 ′, the negative electrode precursor 2 ′, and the separator 3 ′ before winding are preferably configured such that their width dimensions are periodically reduced or increased (more specifically, The width of the electrode precursor stack is periodically reduced or increased when viewed along the direction of the electrode precursor stack where the dimensions are gradually reduced due to winding. Is preferred). In the present invention, the electrode precursor laminate 10 having such a “comb-tooth shape” is applied to the winding (in particular, it is wound so as to be largely bent at the “bending point” shown in FIGS. 8 and 9). The desired "non-rectangular shape" or "step shape" can be obtained.

In the case where the positive electrode precursor 1 ′ and the negative electrode precursor 2 ′ attached to the winding have a comb-tooth shape in a plan view and a wound body including a non-rectangular shape or a step shape is obtained as an electrode winding body, Due to the finer shape of the “comb shape”, higher lamination accuracy is required. That is, when the positive electrode precursor 1 ′ and the negative electrode precursor 2 ′ are overlapped with each other via the separator 3 ′, it is necessary to accurately match the “comb shape” between them. Specifically, it is necessary to align the plurality of narrow portions 11 and the plurality of wide portions 12 in the “comb-tooth shape” with high accuracy without deviation from each other. In this regard, in the manufacturing method of the present invention, the winding deviation due to the pressure heater can be reduced, so that the “comb shape” can be more accurately aligned.

As described above, the manufacturing method of the present invention can suitably cope with “production of electrode winding bodies of“ non-rectangular shape ”and“ step shape ”” having a narrower tolerance for winding deviation. Suitable for mass production of peculiar shaped secondary batteries.

The term “non-rectangular shape” as used in the present invention refers to a shape in which the electrode shape in plan view (or “the shape of the electrode winding body”, hereinafter the same) is not included in the rectangular concept such as a square and a rectangle. It refers to a shape that is partly missing from such a square or rectangle. Accordingly, in a broad sense, “non-rectangular shape” refers to a shape in which the electrode shape in plan view as viewed from above in the thickness direction is not square or rectangular, and in a narrow sense, the electrode shape in plan view is square or rectangular. It is pointed out that it has a shape partially cut away from the base (preferably a shape in which a corner portion of a square or a rectangle of the base is cut out). Although it is merely an example, the “non-rectangular shape” is based on a square / rectangular shape of the electrode in plan view, and a square, rectangular, semi-circular, semi-elliptical, circular / It may be a shape obtained by cutting out a part of an ellipse or a combination thereof from the base shape (particularly a shape obtained by cutting out a corner portion of the base shape) (see FIG. 10). The mode shown in FIG. 10 illustrates a “non-rectangular shape” obtained by cutting a sub-rectangle or sub-square smaller in size from a rectangular or square base shape from the corner portion of the base shape. .

On the other hand, the “step shape” as used in the present invention is broadly defined as a stepped battery outer shape brought about by different height levels of the main surface of the battery (or “main surface of the electrode winding body”). In a narrow sense, it refers to a “staircase” shape composed of a relatively low level battery low surface and a relatively high level battery high surface.

The manufacturing method of the present invention can be embodied in various modes. This will be described in detail below.

(Mode of suitable pressing force)
In the manufacturing method of the present invention, the pressing force of the pressing heater may be adjusted to a pressure that is effective for the pressure heat treatment. In other words, in the present invention, a “pressurizing action” is given to the electrode precursor laminate at the time of winding while giving a “pressurizing action”, but the pressing force is more effective for such processing. be able to.

For example, the pressing force of the pressing heater against the electrode precursor laminate may be a constant pressure condition. Specifically, the pressing force of the pressure heater applied to the electrode precursor laminate may be made substantially constant from the beginning of winding of the electrode precursor laminate to the end of winding. In this way, when the pressing force of the pressing heater is a constant pressure condition, it becomes easy to provide a “pressing action” evenly to the entire wound electrode body in a sectional view. That is, the “pressing action” can be applied evenly not only to the surface side of the electrode winding body but also to a deep portion near the winding center. As a result, inter-layer bonding becomes more uniform as a whole of the electrode winding body, and winding deviation is more effectively prevented. Here, the “constant pressure” is not particularly limited to a strictly constant pressure, and refers to a pressure value fluctuation value within a range of ± 10% during the winding process.

Although it is only an example to the last, the pressing force of the pressing heater with respect to the electrode precursor laminate may be in the range of 0.2 MPa to 2 MPa. That is, the pressure exerted on the electrode precursor laminate during winding by the pressure heater may be in the range of 0.2 MPa to 2 MPa (that is, about 2 kgf / cm ^{2 to} about 20 kgf / cm ² ). . For simplicity, the set value of the pressing force in the pressing heater may be set to such a value, for example, a pressure-sensitive sensor provided in the pressing heater, which receives a pressure received as a reaction from the electrode precursor laminate at the time of winding. The pressure value of the pressure sensitive sensor for detection may be 0.2 MPa or more and 2 MPa or less.

As can be seen from the above, the pressing force of the pressing heater in the present invention broadly means an external force exerted on the electrode precursor laminate at the time of winding, but in a narrow sense, the pressing heater is an electrode at the time of winding. It means the pressure received as a reaction from the precursor laminate.

It can be said that the preferable pressing force is equivalent to a restraining force exerted on the electrode precursor laminate by the pressing heater, preferably 0.2 MPa or more and 2 MPa or less when the pressing heater has a roller form. In this way, by setting the pressing force of the pressure heater to the electrode precursor laminate to about 0.2 MPa or more and 2 MPa or less, both “pressing action” and “heating action” are more effectively exerted on the electrode precursor laminate. be able to.

(Preferable aspect of pressing heater temperature)
In the production method of the present invention, the temperature of the pressure heater may be adjusted to a temperature that is effective for the pressure heat treatment. In other words, in the present invention, while applying the “pressing action” to the electrode precursor laminate at the time of winding, the “heating action” is given, but the temperature is more effective for such processing. be able to.

Although it is merely an example, the temperature of the pressure heater may be in the range of 50 ° C. or more and 200 ° C. or less. That is, the temperature exerted on the electrode precursor laminate at the time of winding by the press heater may be 50 ° C. or more and 200 ° C. or less. More preferably, the temperature of the pressing heater is set to 70 ° C. or more and 150 ° C. or less, and further preferably, the temperature of the pressing heater is set to 70 ° C. or more and 100 ° C. or less. For simplicity, the set value of the temperature in the pressure heater may be set to such a value. For example, the temperature of the pressing heater itself during winding is 50 ° C. or higher and 200 ° C. or lower, preferably 70 ° C. or higher and 150 ° C. or lower, and more preferably 70 ° C. or higher and 100 ° C. or lower.

When the temperature of the pressure heater for the electrode precursor laminate is in the above temperature range, the pressure heat treatment can be performed more effectively. When the temperature of the press heater is particularly lower than 50 ° C., it becomes impossible to extract the adhesive effect of the adhesive layer of the electrode precursor laminate more effectively. On the other hand, when the temperature of the press heater is particularly higher than 200 ° C. The body separator is likely to be adversely affected. For example, when the separator has a microporous membrane shape, when the temperature of the pressure heater exceeds 200 ° C., the “holes” of the separator tend to shrink (they tend to shrink when finally cooled). It becomes easy.

As can be seen from the above description, the temperature of the pressure heater in the present invention broadly means the temperature of the pressure heater itself, but in a narrow sense, the temperature of the surface in contact with the electrode precursor laminate in the pressure heater, In short, it means the temperature of the local portion in the electrode precursor laminate in contact with the pressure heater.

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, when obtaining a flat or flat-plate-shaped electrode winding body, a local portion that is difficult to press, such as a so-called “R portion”, may not be particularly pressed by the pressing heater. Even in such an aspect, in the present invention, the entire electrode winding body can be uniformly subjected to the pressure heat treatment when viewed macroscopically by the heater function of the pressure heater.

The secondary battery according to 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, smartphones, notebook computers and digital cameras, activities, arm computers, and electronic paper). Equipment field), household / small industrial applications (for example, power tools, golf carts, household / nursing / industrial robot fields), large industrial applications (for example, forklifts, elevators, bay harbor crane fields), transportation systems Fields (for example, fields such as hybrid vehicles, electric vehicles, buses, trains, electric assist bicycles, electric motorcycles), power system applications (for example, fields such as various power generation, road conditioners, smart grids, general home-installed power storage systems) IoT field, space and deep sea applications (eg space exploration) , It can be used, such as in the field), such as diving research vessel.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1 'Positive electrode precursor 2 Negative electrode 2' Negative electrode precursor 3 Separator 3 'Separator attached to winding 5 Electrode component layer 10 Electrode precursor laminated body 11 Narrow part 12 Wide part 50

Press heater

50A, 50B Press heater 70 Winding core 100 Electrode winding body

Claims

A method for producing a secondary battery having an electrode winding body composed of a positive electrode and a negative electrode,
The electrode winding body is formed by winding an electrode precursor stack composed of a stack of a positive electrode precursor and a negative electrode precursor via a separator,
In the winding, the electrode precursor laminate is subjected to pressing, and a pressing heater is used for the pressing.
The manufacturing method of the secondary battery of Claim 1 which performs the pressurization heat processing which attach | subjects the said electrode precursor laminated body to both pressurization and heating by the said press by the said press heater.
The method for manufacturing a secondary battery according to claim 2, wherein the pressure heat treatment is performed from the beginning of winding of the electrode precursor laminate.
4. The secondary battery according to claim 2, wherein the pressurization heat treatment is sequentially performed so that the electrode precursor laminate is subjected to both the pressurization and the heating in each rotation of the winding. 5. Production method.
The winding according to any one of claims 2 to 4, wherein the winding is performed using a winding core, and the pressure heat treatment is performed by sandwiching the electrode precursor laminate between the winding core and the pressure heater. The manufacturing method of the secondary battery as described.
The positive electrode precursor and the negative electrode precursor attached to the winding have a comb shape in a plan view, and form a wound body including a non-rectangular shape or a stepped shape as the electrode winding body. Item 6. The method for producing a secondary battery according to any one of Items 1 to 5.
The laminate comprising an adhesive layer as the electrode precursor laminate, wherein the adhesive layer is positioned between at least one of the positive electrode precursor and the negative electrode precursor and the separator. The method for producing a secondary battery according to any one of 1 to 6.
The method for manufacturing a secondary battery according to any one of claims 1 to 7, wherein the pressing heater has a roller shape.
The method for manufacturing a secondary battery according to any one of claims 1 to 8, wherein a temperature of the pressing heater is set to 50 ° C or higher and 200 ° C or lower.
The method for manufacturing a secondary battery according to any one of claims 1 to 9, wherein the pressing force of the pressing heater on the electrode precursor laminate is a constant pressure condition.
The method for manufacturing a secondary battery according to any one of claims 1 to 10, wherein the opposing main surfaces of the electrode precursor laminate are pressed by the pressing heater.
The method of manufacturing a secondary battery according to claim 11, wherein the three-dimensional shape of the electrode winding body is flattened by the pressing of the two main surfaces.