Patent Application
20230048065
The present application claims priority from Japanese Patent Application No. 2021-131373 filed on Aug. 11, 2021, which is incorporated by reference herein in its entirety.
The present invention relates to a method of manufacturing a battery.
JP 2009-193750 A discloses a method of manufacturing an electrode plate group for a non-aqueous electrolyte secondary battery in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are spirally wound with two sheets of separator being stacked together alternately. In the manufacturing method disclosed in the publication, tip parts of the separators are stuck to a winding core while being pressed against the winding core, and the positive electrode plate and the negative electrode plate are sandwiched and wound into a spiral shape.
JP 2011-253701 A discloses a wound element manufacturing apparatus. The manufacturing apparatus disclosed in the publication is provided with a winding core for winding up both electrode foils and both separators on a disk-shaped turret that is rotatable about its central axis as the rotational axis. A plurality of the winding cores are provided intermittently along the rotational direction of the turret.
The present inventors believe that it is desirable to improve productivity of such a method of manufacturing a battery including a wound electrode assembly.
The present disclosure discloses a method of manufacturing a battery including a wound electrode assembly in which a first separator, a negative electrode plate, a second separator, and a positive electrode plate are wound together, the method including the following steps.
Step (A): causing, with the first separator and the second separator being stacked on each other, the first separator and the second separator to be suction-attached to a winding core and to be pressed against the winding core with a jig including a plurality of protrusions formed on a surface of the jig.
Step (B): winding the first separator and the second separator onto the winding core.
Such a method of manufacturing a battery makes it possible to obtain stable product quality of the wound electrode assembly and to improve production yield and productivity.
The jig may be a roller including a plurality of protrusions formed on its outer circumferential surface. The jig may include a plurality of jigs intermittently arranged along an axial direction of the winding core. The winding core may include a plurality of suction holes each including an aperture formed in an outer circumferential surface of the winding core, and a suction passage communicating with the plurality of suction holes. The aperture of each of the suction holes in the outer circumferential surface of the winding core may be smaller than a tip end of each of the protrusions.
In step (A), the protrusions may press, in a region in which the first separator and the second separator are stacked on each other, at least a region having at least a predetermined width from at least one of two opposite widthwise edge portions of the first separator.
In addition, step (B) may include: winding the positive electrode plate between the first separator and the second separator that are to be wound on the winding core; and winding the negative electrode plate between the first separator and the second separator that are to be wound on the winding core. In this case, the first separator and the second separator may be pressed against the winding core with the jig until the winding the positive electrode plate and the winding the negative electrode plate are started.
The winding core may include a plurality of suction holes each including an aperture formed in an outer circumferential surface of the winding core, and a suction passage communicating with the plurality of suction holes. In step (A), at least a portion of the plurality of protrusions of the jig may be disposed outward relative to ones of the suction holes that are located at opposite ends, with respect to the axial direction of the winding core, within a region in which the first separator and the second separator are stacked on each other.
It is also possible that an adhesive layer may be formed on at least one of a surface of the first separator that faces the second separator and a surface of the second separator that faces the first separator.
Embodiments of the invention according to the present disclosure will be described hereinbelow. It should be noted, however, that the disclosed embodiments are, of course, not intended to limit the invention. The present invention is not limited to the embodiments described herein unless specifically stated otherwise. The drawings are depicted schematically and do not necessarily accurately depict actual objects. The features and components that exhibit the same effects are designated by the same reference symbols as appropriate, and the description thereof will not be repeated.
The battery 2 shown in
The outer container 11 is a closed-bottom prismatic case having a horizontally elongated rectangular-shaped enclosing space. The outer container 11 mainly encloses the wound electrode assembly 20. The outer container 11 includes a substantially rectangular-shaped bottom surface 11e, a pair of opposing wider surfaces 11a and 11b (not shown) provided along the longer sides of the bottom surface 11e, and a pair of opposing narrower surfaces 11c and 11d provided along the shorter sides of the bottom surface 11e. An open end 11f is formed facing the bottom surface 11e to accommodate the wound electrode assembly 20. The sealing plate 12 is attached to the open end 11f.
The sealing plate 12 is fitted to the open end 11f of the battery case 10. The sealing plate 12 is composed of a substantially rectangular-shaped plate material that can be fitted to the open end 11f of the outer container 11. The sealing plate 12 is a substantially rectangular-shaped plate material. In the sealing plate 12, a mounting hole 12a for mounting a positive electrode terminal 50 is formed near one longitudinal end thereof, and a mounting hole 12b for mounting a negative electrode terminal 60 is formed near the opposite end.
A filling port 12c and a gas vent valve 12d are provided at a central portion of the sealing plate 12. The filling port 12c is a through hole provided for filling a non-aqueous electrolyte solution into the interior of the battery case 10 that has been hermetically sealed. After filling the non-aqueous electrolyte solution, the filling port 12c is sealed with a sealing member 12e fitted therein. The gas vent valve 12d is a thinned portion that is designed to rupture (i.e., to open) when a large amount of gas is generated inside the battery case 10, so as to expel the gas.
For the non-aqueous electrolyte solution, it is possible to use any non-aqueous electrolyte solution used for conventionally known secondary batteries without any particular limitation. For example, the non-aqueous electrolyte solution may be prepared by dissolving a supporting salt into a non-aqueous solvent. Examples of the non-aqueous solvent include carbonate-based solvents, such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of the supporting salt include fluorine-containing lithium salts, such as LiPF6.
The positive electrode terminal 50 and the negative electrode terminal 60 are attached to the sealing plate 12. The wound electrode assembly 20 is enclosed in the outer container 11, with the wound electrode assembly 20 being attached to the positive electrode terminal 50 and the negative electrode terminal 60. The positive electrode terminal 50 includes an external terminal 51, a shaft member 52, an internal terminal 53, a current collecting member 54, a first insulator 71, a second insulator 72, and a gasket 73. The negative electrode terminal 60 includes an external terminal 61, a shaft member 62, an internal terminal 63, a current collecting member 64, a first insulator 81, a second insulator 82, and a gasket 83. The first insulators 71, 81, the second insulators 72, 82, and the gaskets 73, 83 are each composed of an insulating material. The first insulators 71, 81 and the second insulators 72, 82 are each composed of a resin having required rigidity. The gaskets 73 and 83 are members that are fitted respectively to the mounting holes 12a and 12b of the sealing plate 12 and each have required flexibility.
The respective shaft members 52 and 62 of the positive electrode terminal 50 and the negative electrode terminal 60 are fitted to the mounting holes 12a and 12b of the sealing plate 12 with the respective gaskets 73 and 83 interposed therebetween. The external terminals 51 and 61 are attached to the outside of the sealing plate 12 with the first insulators 71 and 81 interposed therebetween. Each of the external terminals 51 and 61 includes a mounting hole, and is fitted to the outer end of each of the shaft members 52 and 62. The internal terminals 53 and 63 are attached to the inside of the sealing plate 12 with the second insulators 72 and 82 interposed therebetween. Each of the internal terminals 53 and 63 includes a mounting hole, and is fitted to the inner end of each of the shaft members 52 and 62. The inner end of each of the shaft members 52 and 62 is press-fitted to the circumference of the mounting hole of each of the internal terminals 53 and 63. Each of the current collecting members 54 and 64 is attached to one end of each of the internal terminals 53 and 63.
Thus, the positive electrode terminal 50 and the negative electrode terminal 60 are attached to the sealing plate 12, with the positive electrode terminal 50 and the negative electrode terminal 60 being electrically insulated by the first insulators 71, 81, the second insulators 72, 82, and the interposed gaskets 73, 83, and with hermeticity being ensured. Also, an electrically conductive path is formed by the external terminals 51, 61, the shaft members 52, 62, the internal terminals 53, 63, and the current collecting members 54, 64. The wound electrode assembly 20 is fitted to the current collecting members 54 and 64. With the wound electrode assembly 20 being attached to the sealing plate 12 in this way, the wound electrode assembly 20 is enclosed in the outer container 11. It is also possible that a plurality of wound electrode assemblies 20 may be attached to one sealing plate 12. It is also possible that a plurality of wound electrode assemblies 20 may be accommodated in one battery case 10.
The positive electrode plate 21 includes a positive electrode substrate 21a, a positive electrode active material layer 21b, a protective layer 21c, and tabs 21d. The positive electrode substrate 21a is the substrate material of the positive electrode plate 21. The positive electrode substrate 21a is formed of a predetermined metal foil (for example, aluminum foil). The positive electrode active material layer 21b is formed with a constant width on both faces of the positive electrode substrate 21a except for one lateral end portion thereof. The protective layer 21c is formed on both sides of the positive electrode plate 21. The protective layer 21c is formed in a portion of the positive electrode substrate 21a that is other than the portion on which the positive electrode active material layer 21b is formed. In addition, the tabs 21d protruding in a lateral direction are formed at a lateral end of the positive electrode substrate 21a on which the protective layer 21c is formed. The tabs 21d with a predetermined width protrude partially from the lateral end on which the protective layer 21c is formed, so that the positive electrode substrate 21a is exposed.
The positive electrode active material layer 21b is a layer containing a positive electrode active material. In a lithium-ion secondary battery, for example, the positive electrode active material is a material that is capable of releasing lithium ions during charge and absorbing lithium ions during discharge, such as lithium-transition metal composite materials. Generally, other than the lithium-transition metal composite materials, various materials have been proposed for use as the positive electrode active material, and the positive electrode active material is not limited to any particular material. Suitable examples of the positive electrode active material include, for example, lithium-transition metal composite oxides. Among the lithium-transition metal composite oxides, particularly suitable are lithium-transition metal composite oxides containing at least one transition metal selected from the group consisting of nickel (Ni), cobalt (Co), and manganese (Mn). Specific examples include lithium-nickel-cobalt-manganese composite oxide (NCM), lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-manganese composite oxide, lithium-nickel-manganese composite oxide, lithium-nickel-cobalt-aluminum composite oxide (NCA), and lithium-iron-nickel-manganese composite oxide. Suitable examples of lithium-transition metal composite oxides that do not contain Ni, Co, or Mn include lithium-iron-phosphate composite oxide (LFP).
It should be noted that the term “lithium-nickel-cobalt-manganese composite oxide” in the present description means to include oxides that contain additional elements other than the main constituent elements (Li, Ni, Co, Mn, and O). Examples of such additional elements include transition metal elements and main group metal elements, such as Mg, Ca, Al, Ti, V, Cr, Si, Y, Zr, Nb, Mo, Hf, Ta, W, Na, Fe, Zn, and Sn. The additional elements may include metalloid elements, such as B, C, Si, and P, and non-metallic elements, such as S, F, Cl, Br, and I. The positive electrode active material layer 21b may contain addition agents other than the positive electrode active material. Examples of such addition agents may include conductive agents and binders. Examples of the conductive agents include carbon materials such as acetylene black (AB). Examples of the binders include resin binders such as polyvinylidene fluoride (PVdF). When the total solid content of the positive electrode active material layer 21b is 100 mass %, the content of the positive electrode active material may be approximately greater than or equal to 80 mass %, and typically greater than or equal to 90 mass %.
The protective layer 21c is a layer configured to reduce electrical conductivity. Such a protective layer 21c is provided in a region adjacent to an edge portion of the positive electrode active material layer 21b. The protective layer 21c may serve to prevent the positive electrode substrate 21a and the negative electrode active material layer 22b from coming into contact with each other directly and causing internal short circuits when either of the separators 31 and 32 is damaged. For the protective layer 21c, it is possible to form a layer containing electrically insulative ceramic particles, for example. Examples of such ceramic particles include: inorganic oxides, such as alumina (Al2O3), magnesia (MgO), silica (SiO2), and titania (TiO2); nitrides, such as aluminum nitride and silicon nitride; metal hydroxides, such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide; clay minerals, such as mica, talc, boehmite, zeolite, apatite, and kaoline; and glass fibers. Taking electrical insulation and heat resistance into consideration, suitable among them are alumina, boehmite, aluminum hydroxide, silica, and titania. The protective layer 21c may contain a binder for fixing the ceramic particles onto the surface of the positive electrode substrate 21a. Examples of such a binder include resin binders such as polyvinylidene fluoride (PVdF). The protective layer 21c may contain a trace amount of conductive agent (for example, a carbon material such as carbon black). By adding the conductive agent, the protective layer may be made to have slight electrical conductivity. The amount of the conductive agent to be added may be adjusted to an amount that can obtain required electrical conductivity. Note that the protective layer is not an essential constituent component of the positive electrode plate. That is, the secondary battery disclosed herein may also use a positive electrode plate that is not provided with a protective layer.
The negative electrode plate 22 includes a negative electrode substrate 22a, a negative electrode active material layer 22b, and tabs 22d. The negative electrode substrate 22a is the substrate material of the negative electrode plate 22. The negative electrode substrate 22a is formed of a predetermined metal foil (for example, copper foil). The negative electrode active material layer 22b is formed on both sides of the negative electrode substrate 22a substantially along the entire width of the negative electrode substrate 22a. The negative electrode substrate 22a is provided with the tabs 22d protruding from one lateral end thereof. The tabs 22d with a predetermined width protrude partially from the one lateral end of the negative electrode substrate 22a.
The negative electrode active material layer 22b is a layer containing a negative electrode active material. The negative electrode active material is not particularly limited, as long as the negative electrode active material is able to reversibly absorb and release charge carriers in relation to the above-described positive electrode active material. Examples of the negative electrode active material include carbon materials and silicon based materials. The carbon materials may be, for example, graphite, hard carbon, soft carbon, amorphous carbon, and the like. It is also possible to use amorphous carbon-coated graphite, in which the surface of graphite is coated with amorphous carbon, or the like. Examples of the silicon based materials include silicon and silicon oxide (silica). The silicon based materials may also contain other metal elements (such as alkaline-earth metals) and oxides thereof. The negative electrode active material layer 22b may contain addition agents other than the negative electrode active material. Examples of such addition agents may include binders and thickening agents. Specific examples of the binders include rubber-based binders, such as styrene-butadiene rubber (SBR). Specific examples of the thickening agents include carboxymethylcellulose (CMC). When the total solid content of the negative electrode active material layer 22b is 100 mass %, the content of the negative electrode active material is approximately greater than or equal to 30 mass %, and typically greater than or equal to 50 mass %. The negative electrode active material may account for greater than or equal to 80 mass %, or greater than or equal to 90 mass %, of the negative electrode active material layer 22b.
Each of the separators 31 and 32 may be formed of, for example, an electrolyte permeable porous resin sheet with required heat resistance. Various embodiments of the separators 31 and 32 have been proposed, and the separators 31 and 32 are not particularly limited. Suitable examples of the separators 31 and 32 include a separator including a porous substrate layer made of resin such as polyolefin resin [for example, polyethylene (PE) or polypropylene (PP)]. It is also possible that a coat layer may be formed on one side or both sides of the porous substrate layer as appropriate. The coat layer may include an adhesive layer and a porous surface layer containing electrically insulative inorganic material. The porous surface layer is excellent in heat resistance and is therefore able to prevent shrinkage and breakage of the separators 31 and 32 due to temperature increase. Examples of the inorganic materials for the porous surface layer include ceramic particles of alumina, boehmite, aluminum hydroxide, titania, and the like. In addition, the porous surface layer contains a binder for binding the ceramic particles. The binder may be resin binders such as polyvinylidene fluoride (PVdF) and acrylic resins. It should be noted that the two separators 31 and 32 used in the present embodiment may be constructed of either the same or different materials.
As illustrated in
As illustrated in
As illustrated in
Next, a winding machine 100 will be described.
As illustrated in
The winding machine 100 includes, as illustrated in
The transfer path k1 is a path in which the positive electrode plate 21 is delivered from a reel toward the turret 120. The transfer path k2 is a path in which the negative electrode plate 22 is delivered from the reel toward the turret 120. The transfer path k3 is a path in which the first separator 31 is delivered from the reel toward the turret 120. The transfer path k4 is a path in which the second separator 32 is delivered from the reel toward the turret 120. The positive electrode plate 21, the negative electrode plate 22, the first separator 31, and the second separator 32 are each in a strip shape, and they are delivered along predetermined transfer paths k1 to k4, respectively. The transfer path k1 of the positive electrode plate 21 merges with the transfer path k3 of the first separator 31 before reaching the winding core 140 disposed at the first position P1. The transfer path k2 of the negative electrode plate 22 merges with the transfer path k4 of the second separator 32 before reaching the winding core 140 disposed at the first position P1. The transfer paths k1 to k4 may be provided with, for example, a dancer roller mechanism that takes up the slack in the positive electrode plate 21, the negative electrode plate 22, the first separator 31, and the second separator 32 that are delivered, a tensioner that adjusts their tensions, and the like, as appropriate.
The turret 120 is a rotary disk the rotational axis of which is disposed at its center C1. A plurality (three in this embodiment) of winding cores 140 are disposed on the turret 120. The plurality of winding cores 140 are substantially cylindrical-shaped mandrels that are rotatable independently from each other. In this embodiment, the axes of the plurality of winding cores 140 are disposed so as to be parallel to the central axis of the turret 120. The turret 120 is provided with three winding cores 140, a first winding core 140(1), a second winding core 140(2), and a third winding core 140(3). The first winding core 140(1), the second winding core 140(2), and the third winding core 140(3) are disposed around the central axis of the turret 120 so as to be circumferentially equally spaced from each other. The first winding core to the third winding core 140(1)-(3) each have the same configuration. Although not shown in the drawings, the turret 120 is provided with a required actuator (for example, a servomotor) to rotate by an appropriate angle at appropriate timing.
A first position P1, a second position P2, a third position P3 are predetermined around the axis of the center C1 of the turret 120. In
The cutter 151 is a cutter that cuts the separators 31 and 32. The cutter 151 is configured so that its blade 151a is pressed against the separators 31 and 32 that are retained on the winding core 140 disposed at the first position P1. In this embodiment, the cutter 151 may be pushed along a guide to a position defined so that the blade 151a can be pressed against the separators 31 and 32 retained on the winding core 140, and may be retracted from that position. Although not shown in the drawings, the cutter 151 is operated so as to be actuated at appropriate timing by an actuator (for example, a cylinder mechanism). The blade 151a may be, for example, a wavy blade (saw blade).
The presser roller 152 is a roller that presses the separators 31 and 32 against the winding core 140 disposed at the first position P1. The separators 31 and 32 are wound while being pressed onto the winding core 140 disposed at the first position P1 by such a presser roller 152. The presser roller 152 functions as a presser jig that presses the separators 31 and 32 against the winding core 140 disposed at the first position P1. In this embodiment, as illustrated in
The stationary roller 161 is provided at a position at which the transfer path k3 of the first separator 31 and the transfer path k1 of the positive electrode plate 21 merge. The movable roller 171 is a roller that presses the first separator 31 onto the stationary roller 161 to clamp the first separator 31 therebetween. The movable roller 171 is moved in a predetermined direction by means of a guide and an actuator. The movement of the movable roller 171 is controlled by the controller 200. The movable roller 171 is configured to be movable between a position at which it presses the first separator 31 against the stationary roller 161 and a position at which it is detached from the stationary roller 161. The movable roller 171 may be configured to clamp the first separator 31 with a predetermined force by, for example, a spring or the like, when the first separator 31 needs to be clamped. The first separator 31 is clamped by the stationary roller 161 and the movable roller 171 with an appropriate force so that it can be delivered toward the winding core 140 without slack.
The stationary roller 162 is provided at a position at which the transfer path k4 of the second separator 32 and the transfer path k2 of the negative electrode plate 22 merge. The movable roller 172 is a roller that presses the second separator 32 onto the stationary roller 162 to clamp the second separator 32 therebetween. The movable roller 172 is moved in a predetermined direction by means of a guide and an actuator. The movement of the movable roller 172 is controlled by the controller 200. The movable roller 172 is configured to be movable between a position at which it presses the second separator 32 against the stationary roller 162 and a position at which it is detached from the stationary roller 162. The movable roller 172 may be configured to clamp the second separator 32 with a predetermined force by, for example, a spring or the like, when the second separator 32 needs to be clamped. The second separator 32 is clamped by the stationary roller 162 and the movable roller 172 with an appropriate force so that it can be delivered toward the winding core 140 without slack.
The stationary roller 163 is disposed at a predetermined position in the transfer path k3 of the first separator 31, and the stationary roller 163 serves to determine the transfer path k3 of the first separator 31.
As illustrated in
In the state shown in
As illustrated in
In the state shown in
The positive electrode plate 21 and the negative electrode plate 22 may be inserted respectively between the pair of rollers 161 and 171 and between the pair of rollers 162 and 172, for example, after the first separator 31 and the second separator 32 are wound approximately one time around the outer circumferential surface of the winding core 140.
As illustrated in
As illustrated in
The movable roller 174 is a roller that applies tension to the first separator 31 and the second separator 32, as illustrated in
For example, as illustrated in
When the winding core 140(1) moves from the first position P1 to the second position P2, the movable roller 174 is pushed toward the first separator 31 and the second separator 32 at appropriate timing, so as to be pressed onto the first separator 31 and the second separator 32, as illustrated in
The index unit 185 is provided at a central portion of the turret 120. On the turret 120, the three winding cores 140(1)-(3) are distributed uniformly along the circumferential direction, as described previously. The index unit 185 includes a substantially equilateral triangular shaped base that rotates together with the turret 120. At the apexes of the base, respective index rollers 186 to 188 are disposed, and the index rollers 186 to 188 are disposed respectively between the three winding cores 140(1)-(3).
The index unit 185 is constructed as follows. When the winding core 140(1) on which the positive electrode plate 21, the first separator 31, the negative electrode plate 22, and the second separator 32 are wound is moved from the first position P1 to the second position P2, one of the index rollers 186 to 188 that is placed from the first position P1 to the second position P2, namely the index roller 186, is pressed against the first separator 31 and the second separator 32 from radially inside. Such an index roller 186 and the movable roller 174 allow the first separator 31 and the second separator 32 to be delivered between the first position P1 and the second position P2 without causing slack. At the time shown in
As illustrated in
Furthermore, in this embodiment, as illustrated in
The present inventors believe that the winding machine 100 as described above desirably allows the first separator 31 and the second separator 32 to be retained on a winding core 140 in a stable manner, to stabilize the shape of the wound electrode assembly 20. Herein, in association with the method of manufacturing a battery 2 including a wound electrode assembly 20 in which a first separator 31, a negative electrode plate 22, a second separator 32, and a positive electrode plate 21 are wound together, the winding machine 100 embodies the following steps (A) and (B).
Step (A): Step (A) involves causing, with the first separator 31 and the second separator 32 being stacked on each other, the first separator 31 and the second separator 32 to be suction-attached to a winding core 140 and causing the first separator 31 and the second separator 32 to be pressed against the winding core 140 with a jig including a plurality of protrusions formed on a surface of the jig (see
Step (B): Step (B) involves winding the first separator 31 and the second separator 32 onto the winding core 140 (see
Step (A) and step (B) are, for example, applied to the start of winding a wound stack 20a. At the start of winding of the wound stack 20a, the first separator 31 and the second separator 32 are placed on the winding core 140. At that time, in step (A), the first separator 31 and the second separator 32 may be caused, with the first separator 31 and the second separator 32 being stacked on each other, to be suction-attached to the winding core 140 and to be pressed against the winding core 140 with the jig including a plurality of protrusions formed on a surface of the jig. As a result, the first separator 31 and the second separator 32 are suction-attached to the winding core 140 stably while they are in a stacked condition. This enables the wound electrode assembly 20 to obtain a stable shape at the start of winding. Thus, the first separator 31 and the second separator 32 are suction-attached to the winding core 140 in step (A), and thereafter, the first separator 31 and the second separator 32 are wound onto the winding core 140 in step (B). In step (B), the first separator 31 and the second separator 32 may be wound, for example, approximately one time around the winding core 140. Thereafter, the positive electrode plate 21 and the negative electrode plate 22 may be inserted into a predetermined position, then the first separator 31, the separator 31, the positive electrode plate 21, and the negative electrode plate 22 may be stacked in a predetermined order and wound around the winding core 140 (see
In the embodiment shown in
When the first separator 31 and the second separator 32 are pulled out from a reel (not shown) and loaded into the winding machine 100 for the first time, the first separator 31 and the second separator 32 may be loaded into the winding machine 100, for example, in such a condition that the first separator 31 and the second separator 32 are stacked and suction-attached onto the winding core 140 disposed at the first position P1. Then, the first separator 31 and the second separator 32 are wound approximately one time around the winding core 140, and the turret 120 is turned to dispose another winding core 140 to be positioned at the first position P1 (see
Thus, step (A) and step (B) are applied when the first separator 31 and the second separator 32 pulled out from the reel are loaded into the winding machine 100 for the first time and winding of the wound stack 20a is started. Such step (A) and step (B) enable the first separator 31 and the second separator 32 to start to be wound on the winding core 140 more efficiently and with a more stable shape. As a result, it is possible to obtain stable product quality of the wound electrode assembly 20 and to improve production yield and productivity.
In step (A), the jig including a plurality of protrusions formed on a surface of the jig may be, for example, a roller 152 (presser roller 152) including a plurality of protrusions 152a formed on an outer circumferential surface of the roller 152, as illustrated in
To address this issue, the embodiment shown in
From the above-described viewpoint, in other words, the tip end of each of the protrusions 152a of the presser roller 152 may have a sufficiently wide area such as not to fit into the aperture of each of the suction holes 141 in the outer circumferential surface of the winding core 140. For example, the aperture of the suction hole 141 in the outer circumferential surface of the winding core 140 and the tip end of the protrusion 152a of the presser roller 152 may each have a circular shape. When this is the case, the inner diameter of the aperture of the suction hole 141 may be smaller than the outer diameter of the tip end of the protrusion 152a. It should be noted that the tip end of each of the protrusions 152a of the presser roller 152 may not necessarily be a flat surface but may be a gently curved surface. When the tip end of each of the protrusions 152a of the presser roller 152 is a flat surface, its peripheral edge portion may be chamfered or processed to be in a round shape. Alternatively, the tip end of each of the protrusions 152a of the presser roller 152 may be subjected to a surface treatment such as not to damage the separators 31 and 32.
Herein, the size of the aperture of each of the suction holes 141 may be assessed, for example, by the maximum width of the aperture of each of the suction holes 141. When the aperture of the suction hole 141 is in a circular shape, the size thereof may be the inner diameter of the aperture. When the aperture of the suction hole 141 is odd-shaped, the size may be the maximum diameter thereof. In addition, the tip end of each of the protrusions 152a of the presser roller 152 may be flat. In this case, the size of the tip ends of the protrusions 152a of the presser roller 152 may be assessed by the minimum diameter of the tip ends of the protrusions 152a.
It is also possible that, for example, the outer diameter of the tip ends of protrusions of the jig (roller) provided with the plurality of protrusions on a surface thereof may be smaller than the aperture diameter of the suction holes 141 provided in the winding core 140. Herein, when the end face of each tip end of the protrusions is not a perfect circle, the outer diameter of the tip ends of the protrusions may be assessed by the outer diameter of the portion of the tip end that has the smallest outer diameter. When the aperture of each of the suction holes provided in the winding core is not a perfect circle, the diameter of the aperture is assessed by the diameter of the portion thereof that has the smallest diameter. Moreover, as for the jig (roller) including a plurality of protrusions provided on its surface, the minimum distance between the tip ends of adjacent ones of the protrusions may be less than the minimum distance between adjacent ones of the suction holes 141 of the winding core 140. In this case as well, the protrusions of the jig (roller) are less likely to fit into the suction holes 141 of the winding core 140, preventing the separators 31 and 32 from being damaged. Furthermore, when the tip ends of the protrusions are formed to have a relatively smaller outer diameter, the two separators 31 and 32 that are pressed by the jig are effectively caused to stick together easily. As described above, the protrusions of the jig (roller) may be made less prone to fit into the suction holes 141 of the winding core 140.
In step (A), of the two opposite widthwise edge portions within the region in which the first separator 31 and the second separator 32 are stacked on each other, a region of at least one of the widthwise edge portions having a predetermined width may be pressed by the protrusions 152a of the presser roller 152. In this case, it is possible that the first separator 31 and the second separator 32 happen to be slightly staggered in a widthwise direction. Even in such a case as well, the protrusions may press, in the region in which the first separator 31 and the second separator 32 are stacked on each other, at least a region with a predetermined width from at least one of the two opposite widthwise edge portions of the first separator 31.
For example, as illustrated in
It is also possible that step (B) may include winding the positive electrode plate 21 onto a radially inward side of the first separator 31 that is to be wound on the winding core 140; and winding the negative electrode plate 22 between the first separator 31 and the second separator 32 that are to be wound on the winding core 140. In this case, the negative electrode plate 22 is wound on an outward side of the first separator 31, the second separator 32 is wound on an outward side of the negative electrode plate 22, and the positive electrode plate 21 is wound on an outward side of the second separator 32. In this case, in step (B), the first separator 31 and the second separator 32 may be pressed against the winding core 140 with the presser roller 152 (jig) until the winding the positive electrode plate 21 and the winding the negative electrode 22 plate are started. This prevents the gap between the first separator 31 and the second separator 32 from widening until the winding the positive electrode plate 21 and the winding the negative electrode 22 plate are started. For this reason, the winding of the positive electrode plate 21 and the winding of the negative electrode plate 22 can be started in a stable manner.
Furthermore, in this embodiment, the winding core 140 includes the plurality of suction holes 141 each including an aperture formed in an outer circumferential surface of the winding core 140, and the suction passage 142 communicating with the plurality of suction holes 141, as illustrated in
It is also possible that an adhesive layer may be formed on at least one of a surface of the first separator 31 that faces the second separator 32 and a surface of the second separator 32 that faces the first separator 31. This enables the first separator 31 and the second separator 32 that are overlaid on the winding core 140 to be bonded together by the action of the adhesive layer. As a result, the starting end portion of the winding at which the first separator 31 and the second separator 32 start to be wound onto the winding core 140 can be wound onto the winding core 140 in a more stable manner. Therefore, it is possible to prepare the wound electrode assembly 20 more efficiently and with a more stable shape.
In this case, the adhesive layer to be formed on the separators 31 and 32 may be a layer having a three-dimensional network structure containing PVdF. In this case, the adhesive layer may have a structure (three-dimensional network structure) such that a plurality of fibrous PVdF are gathered and randomly stacked to form a large number of pores (voids). When the adhesive layer is formed on at least one of the surface of the first separator 31 that faces the second separator 32 and the surface pressure of the second separator 32 that faces the first separator 31, the adhesive layers having such a three-dimensional network structure are brought into contact with each other. This serves to produce static electricity at the contact surface between the first separator 31 and the second separator 32 and prevents the separators 31 and 32 from being staggered from each other. Moreover, such static electricity also serves to prevent the separators from being staggered from the winding core 140. For example, the adhesive layer may be provided on both surfaces of a portion of the first separator 31 that is directly wound onto the outer circumferential surface of the winding core 140. This prevents defects from occurring at the starting end of the separators, and enables continuous manufacturing of wound electrode assemblies 20. More specifically, even when the separator includes the adhesive layer on the substrate layer or on both surfaces of the substrate layer, the above-described embodiment makes it possible to effectively prevent a misalignment of the separators 31 and 32 with respect to the winding core 140 in a simple manner, and to improve productivity.
Herein, the substrate material for the separators 31 and 32 may be, for example, a porous polyolefin-based substrate material. Also, the adhesive layer of the separators 31 and 32 may contain, in addition to the above-mentioned PVdF, one or more types of inorganic particles, for purposes of improving the strength, for example. The materials for the inorganic particles may include previously mentioned examples of the inorganic particles that may be contained in the separators 31 and 32. Among them, alumina, boehmite, silica, and titania, which are stable in product quality and available at low cost, may be used suitably in terms of both cost and functionality. In this case, the proportion of the PVdF and the inorganic particles contained in the adhesive layer may be such that the inorganic particles is greater in mass ratio than the PVdF. The adhesive layer may contain, for example, at least 10 mass % of PVdF. The inorganic particles may be, for example, distributed (i.e., dispersed) substantially uniformly in the three-dimensional network structure formed by resin such as the above-mentioned PVdF. As described above, when an adhesive layer is formed appropriately on a surface of the separators 31 and 32, static electricity is easily generated in the separators 31 and 32, which serves to eliminate a misalignment of the separators 31 and 32 with respect to the winding core 140 and allows the winding core 140 to suction-attach the separators 31 and 32 easily.
Hereinabove, embodiments of the method of manufacturing a battery according to the present disclosure and embodiments of the winding machine 100 that embodies the method have been described in detail. The winding machine 100 is merely an embodiment of the winding machine that embodies the method of manufacturing a battery, and the winding machine that embodies the method of manufacturing a battery is not limited to the above-described embodiments, unless specifically stated otherwise. For example, in the embodiments described above, three winding cores 140 are provided on the turret 120, and they are configured to be simultaneously moved by rotation of the turret 120. It is also possible that the turret 120 may be provided with a further greater number of winding cores, and a plurality of processes may be performed at a plurality of positions in parallel. Unless specifically stated otherwise, the plurality of winding cores may not be provided on the turret, and the plurality of winding cores may be configured to move independently from each other. Furthermore, even when the steps in the above method of manufacturing a battery are carried out in parallel, these steps may be either started simultaneously or started at shifted times appropriately.
The foregoing embodiments illustrate suction-attachment to the winding core as the mechanism of retaining the first separator and the second separator onto the winding core. Unless otherwise stated, the winding machine is not limited to such embodiments. For example, it is possible to adopt a mechanism that retains the first separator and the second separator on the winding core by pressing a roller against the winding core.
In the foregoing embodiments, the first separator 31 and the second separator 32 are cut at the groove 143 provided in the outer circumferential surface of the winding core 140. Unless otherwise stated, the winding machine is not limited to such embodiments. For example, the first separator and the second separator may be cut at a location on the winding core, not limited to the groove, for example, at a location at which they are in contact with the outer circumferential surface of the winding core. Alternatively, the first separator and the second separator may be cut at a location near the winding core, that is, at a location that is close to the winding core at which the first separator is not in contact with the outer circumferential surface of the winding core. For example, the cut position may be set to be less than or equal to 5 cm, or less than or equal to 3 cm, away from the position at which the first separator is in contact with the winding core. The closer the cut position is to the position at which the first separator is in contact with the winding core, the more likely it may be to reduce excessive separator remaining inside the wound electrode assembly 20 or to prevent the starting end portion of winding from bending.
Although the cylindrically shaped presser roller 152 is illustrated as an example of the presser jig, the presser jig is not limited to the embodiment of roller, but may be any member that presses the first separator 31 and the second separator 32 onto the winding core 140 disposed at the first position P1.
Various embodiments of the invention have been described hereinabove according to the present disclosure. Unless specifically stated otherwise, the embodiments described herein do not limit the scope of the present invention. It should be noted that various other modifications and alterations may be possible in the embodiments of the invention disclosed herein. In addition, the features, structures, or steps described herein may be omitted as appropriate, or may be combined in any suitable combinations, unless specifically stated otherwise.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-131373 | Aug 2021 | JP | national |
