JP4316861B2 - Square battery and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flat prismatic battery in which a power generation element is housed in a battery case in which an opening of a main body case formed in a half-shell is sealed by a cover plate, and a method for manufacturing the same.
[0002]
[Prior art]
Portable electronic devices such as mobile phones and PDAs are becoming increasingly smaller and thinner with higher functionality, and the batteries applied to them are required to be smaller and thinner and have a higher energy density. A flat rectangular lithium ion secondary battery is widely used. The battery case applied to the flat rectangular battery is composed of a battery can formed into a bottomed rectangular tube shape by deep drawing and a sealing plate that closes the open end thereof. A power generation element made of an electrolytic solution is accommodated.
[0003]
In order to achieve thinning of the battery, it is necessary to deeply draw the battery can into a narrower rectangular tube. However, as the opening area becomes smaller with respect to the depth in the processing direction, the processing becomes more difficult, There is a limit to reducing the thickness of battery cans by drawing. It is also difficult to insert the electrode plate group into the battery can formed in a narrow and deep cylindrical shape as the opening area is reduced by reducing the thickness.
[0004]
Therefore, in order to further reduce the thickness of a prismatic battery that is limited in thickness, it is necessary to change the structure of the battery case. The main body case formed in the half-shell and the opening of the main body case are closed. A battery in which a battery case is formed by a lid plate formed on a flat plate or a half shell has been developed.
[0005]
For example, as shown in FIG. 15, there is known a prismatic battery in which an electrode plate group 3 is accommodated in an upper cup 1 and an opening thereof is sealed by a lower cup 2 (see Patent Document 1). In this battery case structure, since the recess for accommodating the power generation element can be formed by shallow drawing, the battery case can be easily manufactured.
[0006]
When housing the electrode plate group in the battery case, it is necessary to insulate the positive electrode plate or the negative electrode plate constituting the electrode plate group from coming into contact with the battery case. Then, an insulation process for arranging the insulating plate is performed. However, the number of work steps increases due to the insulation treatment, and the production cost also increases. In a prismatic battery using a conventional cylindrical battery can, a method of covering an edge of an electrode plate with a separator constituting an electrode plate group is disclosed (see Patent Document 2).
[0007]
As shown in FIG. 16, when the electrode plate group 9 wound with the width of the separator constituting the electrode plate group 9 made larger than that of the positive electrode plate and the negative electrode plate is inserted into the battery can 8, the separator protrudes from the positive and negative electrode plates. Since the edges of the positive and negative plates are bent to cover the edges of the positive and negative plates, insulation between the positive and negative plates and the battery can 8 is possible without providing the insulation treatment as described above.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-250517 (pages 2 to 4, FIG. 1)
[0009]
[Patent Document 2]
Japanese Patent No. 2697565 (pages 1 and 2, FIG. 2)
[0010]
[Problems to be solved by the invention]
However, in the above-described prior art, the configuration in which the edge of the positive and negative electrode plates is covered with the separator is that when the electrode plate group is inserted into the cylindrical battery can, the separator is bent so as to cover the edge of the positive and negative electrode plates. The separator is thin and soft and cannot be expected to bend in the direction of covering the edges of the positive and negative electrode plates, and there is a problem that a reliable insulation treatment state cannot be obtained.
[0011]
In the configuration using the main body case formed in the half shell as described above instead of the cylindrical battery can, the width of the separator is larger than the width of the positive and negative electrode plates and larger than the width of the concave portion of the main body case. When the formed electrode plate group is inserted into the main body case, the edge of the separator is bent downstream in the insertion direction, so that the edges of the positive and negative electrode plates are securely covered, and without the insulating treatment, The separator can be insulated from the battery case.
[0012]
However, as shown in FIG. 17, there is a possibility that the upper layer separator 49 may be placed on the flange portion 13 for sealing the opening of the main body case 11 with the cover plate 12, and the separator 49 is placed on the flange portion 13. When the cover plate 12 is welded to the flange portion 13, there is a possibility that the separator 49 is interposed at the welded portion, causing poor welding and impairing the airtightness in the battery case.
[0013]
An object of the present invention is to provide a prismatic battery provided with an insulating structure for an electrode plate group suitable for a prismatic battery using a battery case having a structure in which a half shell case is closed by a lid plate, and a method for manufacturing the prismatic battery. is there.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the first invention of the present application is that a positive electrode plate and a negative electrode plate are wound flatly through a separator in a recess of a main body case in which a joint is formed at an opening of a quadrangular half-shell. A prismatic battery in which a concave portion of the main body case is closed, a lid plate placed on the joint portion is welded to the joint portion, and the inside of the concave portion is sealed. the width in the direction perpendicular to the winding direction, the positive electrode plate and the negative electrode plate is smaller than the width dimension in the recess, the separator Ri Na is larger than the recess width dimension, recess peripheral wall of the body case to the cover plate A recess is formed toward the inside of the recess with a position a predetermined distance away from the inner wall, and the outer dimension is smaller than the recess inner width dimension and the inner dimension is the positive electrode between the outer periphery wall of the recess and the inner peripheral wall of the recess. An insulating frame formed larger than the width of the plate and the negative plate is inserted. To become Te said.
[0015]
According to the above configuration, when the electrode plate group is inserted into the recess, the end of the separator formed larger than the inner width dimension of the recess is bent downstream in the insertion direction of the electrode plate group. Is covered with the edge of the folded separator, and an internal short circuit due to the positive and negative electrode plates coming into contact with the main body case can be prevented. Therefore, the electrode plate group itself constitutes an insulating means without using a separate insulating member.
[0017]
Further, a recess is formed in the lid plate toward the inside of the recess with a position away from the inner peripheral wall of the recess of the main body case as an outer peripheral wall, and an outer dimension is defined between the outer peripheral wall of the recess and the inner peripheral wall of the recess. Since it is configured to insert an insulating frame that is smaller than the inner width of the recess and larger than the width of the positive electrode plate and the negative electrode plate, it is folded when the electrode plate group is inserted into the main body case. end sides of the upper separator curved Ki de be pressed by the frame and the end side of the upper separator it is possible to prevent a failure of the pinched welding between the cover plate resting on the flange portion.
[0018]
In addition, the second invention of the present application includes an electrode plate group in which a positive electrode plate and a negative electrode plate are wound flatly via a separator in a concave portion of a main body case in which a joint is formed in an opening of a rectangular half-shell. In the method of manufacturing a rectangular battery that accommodates and closes the concave portion of the main body case and welds the lid plate placed on the joint portion to the joint portion and seals the inside of the concave portion, the electrode plate group has its winding direction The width of the positive electrode plate and the negative electrode plate is smaller than the inner width dimension of the recess, and the separator is larger than the inner width dimension of the recess. Is a method of manufacturing a prismatic battery that is bent downstream in the insertion direction and is interposed between the end of the positive electrode plate and / or the negative electrode plate and the inner peripheral wall of the recess, and when the electrode plate group is inserted into the recess , At least between the side surface orthogonal to the winding direction of the electrode plate group and the inner wall of the recess Insert the resin film, by heating the part which projects into the recess outside of the resin film is softened, wherein the shaping folded onto the electrode plate group with the end side of the folded separator.
[0019]
According to the above manufacturing method, when the electrode plate group is inserted into the recess, the edge of the separator formed larger than the width of the recess is bent downstream in the insertion direction of the electrode plate group. The part is covered with the edge of the bent separator, and an internal short circuit due to the positive and negative electrode plates coming into contact with the main body case can be prevented. Therefore, the positive and negative electrode plates can be insulated by the electrode plate group itself without using a separate insulating member.
[0020]
Further , when inserting the electrode group into the recess, insert a resin film between at least the side surface orthogonal to the winding direction of the electrode group and the inner wall of the recess, and heat the portion of the resin film protruding outside the recess. Softened and folded on the electrode plate group together with the edge of the folded separator, so that in addition to the edge of the folded separator, the end of the positive and negative electrode plates and the main body case are made of resin film. together achieve insulation between, Ki de be kept on the electrode plate group with the resin film formed by bending the edge of the upper layer of the separator curved broken upon insertion into the body case of the electrode plate group, the end edges of the upper separator It is possible to prevent welding from being hindered by being placed on the flange portion and sandwiched between the cover plate and the cover plate.
[0021]
By applying a material whose softening temperature is lower than the melting temperature of the separator, the resin film can be shaped by heating without melting the separator.
[0022]
Further, the third invention of the present application is a group of electrode plates in which a positive electrode plate and a negative electrode plate are wound flatly through a separator in the concave portion of the main body case in which a joint is formed in the opening of the rectangular half-shell. In the method of manufacturing a rectangular battery in which the concave portion of the main body case is closed and the lid plate placed on the joint portion is welded to the joint portion to seal the inside of the concave portion, The positive electrode plate and the negative electrode plate are formed to have a width smaller than the recess inner width dimension, the separator is formed larger than the recess inner width dimension, the outer dimension is smaller than the recess inner wall width dimension, the inner dimension is By inserting the electrode plate group into the recess through an insertion jig formed in a frame shape larger than the width dimension of the negative electrode plate, the end side of the separator is bent to the downstream side in the insertion direction by the insertion jig. The plate group is inserted into the recess.
[0023]
According to the above manufacturing method, when the electrode plate group is inserted into the recess through the insertion jig, the end side of the separator is shaped by the insertion jig into a state bent to the downstream side in the insertion direction of the electrode plate group, and into the recess. Inserted. Since the separator is thin and soft, it may not be bent in a certain direction depending on the contact state when it is directly inserted into the recess. available. The ends of the positive and negative electrode plates are covered with the edge of the bent separator, and an internal short circuit due to the positive and negative electrode plates coming into contact with the main body case can be prevented. Therefore, the positive and negative electrode plates can be insulated by the electrode plate group itself without using a separate insulating member.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
[0025]
FIG. 1 shows the external shape of a prismatic battery according to this embodiment, which is configured as a lithium ion secondary battery. This rectangular battery is composed of a battery main body 20 shown in FIG. 2 and an exterior body 30 covering the battery main body 20.
[0026]
As shown in FIG. 3 in which the battery body 20 is disassembled into components, a battery case 10 is constituted by a body case 11 formed in a half-shell and a lid plate 12 that closes an open portion thereof. The electrode plate group 14 is accommodated in the recess 15 of the main body case 11, the periphery of the cover plate 12 is welded to the flange portion 13 formed in the main body case 11, and the opening of the main body case 11 is sealed with the cover plate 12. It is configured as follows.
[0027]
The main body case 11 is formed by pressing a ferrous plate material such as stainless steel or cold-rolled steel plate to provide a step portion 16 having a reduced drawing depth on one end side to form a concave portion 15, and around the concave portion 15. A flange portion 13 is provided and formed. The step portion 16 is a portion for forming positive and negative external connection terminals. Here, the terminal hole 17 formed in the step portion 16 is insulated from the main body case 11 by the lower gasket 18, and the rivet 19 is secured to ensure airtightness. Thus, the PTC unit 26 is fixed on the outer surface of the step portion 16.
[0028]
As shown in FIG. 4, the PTC unit 26 accommodates a PTC element 33 in which an upper electrode 33b and a lower electrode 33c are joined to both surfaces of a PTC conductive polymer 33a in a PTC holder 34, and a step portion is formed by an upper gasket 35. The rivet 19 is fastened with a washer 37 insulatively and is fixed on the stepped portion 16, and a holder plate 36 is welded to the opening of the PTC holder 34. Here, the holder plate 36 constitutes a positive external connection terminal. The PTC (Positive Temperature Coefficient) element 33 is a device whose temperature rises due to overcurrent or overheating and the resistance value suddenly rises when the element temperature reaches a predetermined temperature. Power loss is kept low, and when the temperature reaches a predetermined temperature, the resistance value rises rapidly from the fourth power to the sixth power, so when an external short circuit occurs, the temperature rises and the short circuit current is suppressed, and the battery is shorted externally. Protect from.
[0029]
The electrode plate group 14 in which the positive electrode plate 47 and the negative electrode plate 48 are wound flatly via a separator 49 is accommodated in the recess 15 of the main body case 11. As shown in FIG. 5, the electrode plate group 14 is wound so that the outermost periphery is the negative electrode plate 48, and the winding direction is a direction from the step portion 16 toward the opposite side, and the winding end end is The positive electrode lead 21 and the negative electrode lead 22 are drawn out from the winding end ends of the positive electrode plate 47 and the negative electrode plate 48 so as to be on the stepped portion 16 side. The positive electrode lead 21 has an extension portion from the winding end of the positive electrode plate 47 at an appropriate width as a lead at a position on the extension line of the rivet 19 attached on the step portion 16, and the electrode plate group 14 is placed in the recess 15. It is formed by cutting so that the tip end portion has a length located on the rivet 19 when stored in the container. Also, the negative electrode lead 22 has an appropriate width as a lead with an extension portion from the winding end of the negative electrode plate 48 at a position on the extension line at an arbitrary position where no member such as the rivet 19 on the step portion 16 exists. When the plate group 14 is housed in the recess 15, it is formed by cutting so that the tip portion has a length located on the step portion 16.
[0030]
Further, as shown in FIG. 6, the separator 49 is formed so that the width in the direction orthogonal to the winding direction is larger than the width of the positive electrode plate 47 and the negative electrode plate 48 and larger than the width dimension of the recess 15.
[0031]
As shown in FIG. 7, the electrode plate group 14 configured as described above has the side where the positive electrode lead 21 and the negative electrode lead 22 are drawn into the recess 15 of the main body case 11 as the stepped portion 16 side, and the end of winding. Store so that is on the outside. At this time, the end of the separator 49 protruding from the side surface in the direction orthogonal to the winding direction of the electrode plate group 14 is on the downstream side in the insertion direction into the recess 15 of the electrode plate group 14 as shown in FIG. Since it is bent, the bent separator 49 serves as an insulating means for preventing the positive electrode plate 47 from coming into contact with the main body case 11 having a negative electrode potential.
[0032]
However, since the separator 49 is thin and soft, it cannot be understood in which direction the end side bends depending on the contact state when the electrode plate group 14 is inserted into the main body case 11. Therefore, when the electrode plate group 14 is inserted into the concave portion 15 of the main body case 11, it is necessary to shape or carefully insert the separator 49 so that the end side of the separator 49 is bent to the downstream side in the insertion direction. This lowers the workability of battery manufacture. Therefore, as shown in FIG. 9, an insertion jig is used so that the end side of the separator 49 is always bent in a certain direction when the electrode plate group 14 is inserted into the main body case 11. It is preferable to insert the electrode plate group 14 into the main body case 11 using 52.
[0033]
As shown in FIG. 10, the insertion jig 52 has a width in the direction orthogonal to the winding direction of the electrode plate group 14 larger than the width of the positive and negative electrode plates 47 and 48 of the electrode plate group 14 in the inner dimension. The outer dimension is formed in a frame shape smaller than the width dimension of the recess 15. As shown in FIG. 9, when the electrode plate group 14 is inserted into the recess 15 through the insertion jig 52, the edge of the separator 49 is bent and aligned on the downstream side in the insertion direction when passing through the insertion jig 52. And is inserted into the recess 15 as it is.
[0034]
When the electrode plate group 14 is housed in the recess 15, the end of the positive electrode lead 21 is positioned at a slightly higher height than the stepped portion 16 as shown in FIG. Since the tip portion of the negative electrode lead 22 is located on the step portion 16 and located on the rivet 19, the positive lead 21 is joined to the rivet 19 and the negative lead 22 is joined to the step portion 16 without drawing the lead. Can do.
[0035]
The opening of the main body case 11 in which the electrode plate group 14 is accommodated is such that the cover plate 12 is placed on the flange portion 13 and the flange portion 13 and the cover plate 12 are positioned so that their outer edge ends coincide. It is sealed by welding between the peripheral part of the cover plate 12 and the flange part 13.
[0036]
As shown in FIG. 3, the cover plate 12 is formed with a shallow recess 23 at the center, and when the battery case 10 is expanded due to expansion of the electrode plate group 14 or an increase in internal pressure, the expansion is reduced. Is absorbed within the formation depth, so that the overall thickness of the rectangular battery does not change.
[0037]
Further, as shown in FIG. 8, the recess 23 formed in the cover plate 12 is formed at a predetermined interval from the inner wall of the recess of the main body case 11, so that the space between the outer peripheral wall of the recess 23 and the inner peripheral wall of the recess 15 is formed. The space formed in this is an accommodation space for the upper-layer separator 49 that is bent when the electrode plate group 14 is inserted into the main body case 11. If the lid plate 12 is placed on the flange portion 13 and welded without the folded separator 49 accommodating space, welding may be performed with the separator 49 sandwiched between the lid plate 12 and the flange portion 13. However, the lack of sealing performance due to poor welding occurs. However, since the storage space for the separator 49 is formed, the protruding upper layer separator 49 is stored in the storage space.
[0038]
Further, when the electrode plate group 14 is inserted into the main body case 11, a frame body 50 as shown in FIG. 11 is used in order to more reliably process the upper separator 49 that protrudes upward from the recess 15 of the main body case 11. It can be configured to be placed on the electrode plate group 14 accommodated in the main body case 11 and to hold the upper separator 49. When the recess 15 of the main body case 11 is sealed by the cover plate 12, the frame body 50 is formed between the outer peripheral wall of the recess 23 formed in the cover plate 12 and the inner peripheral wall of the recess 15 as shown in FIG. Since the edge of the upper layer separator 49 is held inward by being housed in the housing space, the folded separator 49 does not rest on the flange portion 13 and cause poor welding.
[0039]
Further, when the electrode plate group 14 is inserted into the main body case 11, a resin sheet 51 is inserted between the electrode plate group 14 and the inner wall of the recess 15 as shown in FIG. ), The resin sheet 51 can be softened by heating and bent inward, and the end of the separator 49 can be fixed on the electrode plate group 14. By setting the softening temperature of the resin sheet 51 higher than the melting temperature of the separator 49, the separator 49 is not melted by heating. Here, since the resin sheet 51 is impregnated with the electrolytic solution with respect to the electrode plate group 14, the resin sheet 51 is porous with moderately open holes. In order to enhance the impregnation property, the resin sheet 51 is formed into a shape having excellent liquid permeability such as a mesh shape, or only a part of the group side surface is covered so as not to cover the entire surface. There is.
[0040]
A predetermined amount of electrolytic solution is injected from an electrolytic solution injection port 28 formed in the stepped portion 16 into the concave portion 15 in which the electrode plate group 14 is accommodated and sealed by welding the lid plate 12, and the injection is completed. Later, a sealing plug 29 is inserted into the electrolyte solution inlet 28, and the recess 15 is sealed by welding the sealing plug 29 to the stepped portion 16.
[0041]
As shown in FIG. 14, the battery body 20 formed as described above is covered with a resin cover 25 formed by resin molding, and a rectangular film shown in FIG. Formed. The resin cover 25 has a positive terminal window 31 that opens on the holder plate 36 of the PTC unit 26 fixed on the outer surface of the step portion 16 and a portion on the bottom surface of the main body case 11 where the step portion 16 is not formed. A negative electrode terminal window 32 is formed, and notches are formed in the positive electrode terminal window 31 and the negative electrode terminal window 32 so that the resin film 38 is not wound around. Since the holder plate 36 serving as an external connection terminal is exposed to the outside and the main body case 11 serving as the negative electrode external connection terminal is exposed from the negative electrode terminal window 32, it can be used for external connection.
[0042]
【The invention's effect】
As described above, according to the present invention, when the electrode plate group is housed in the recess of the main body case formed in the half-shell, the separator formed wider than the positive and negative electrode plates is bent to end the positive and negative electrode plates. Since the portion is covered, an insulating means for preventing an internal short circuit is provided without separately providing an insulating means.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external shape of a prismatic battery according to an embodiment.
FIG. 2 is a perspective view showing an external shape of a battery main body constituting the same rectangular battery.
FIG. 3 is an exploded perspective view showing a configuration of a battery main body.
FIG. 4 is a cross-sectional view showing a configuration of a PTC unit.
FIG. 5 is a perspective view showing a lead drawing structure.
FIG. 6 is a partial cross-sectional view showing a configuration of an electrode plate group.
FIG. 7 is a perspective view showing a state in which the electrode plate group is stored in the main body case.
FIG. 8 is a partial cross-sectional view showing the separator in a bent state.
FIG. 9 is a schematic view showing a method for inserting a plate group using an insertion jig.
FIG. 10 is a perspective view showing a configuration of an insertion jig.
FIG. 11 is a perspective view showing a configuration of a frame.
FIG. 12 is a cross-sectional view showing a separator pressing structure using a frame.
FIG. 13 is a partial sectional view showing a shaping structure of a separator made of a resin film.
FIG. 14 is a perspective view showing the formation of an exterior body on the battery body.
FIG. 15 is an exploded perspective view showing a configuration of a square battery according to the prior art.
FIG. 16 is a perspective view showing an insulating structure using a separator according to the prior art.
FIG. 17 is a partial cross-sectional view illustrating a problem of an insulating structure by a separator edge.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Battery case 11 Main body case 12 Cover plate 13 Flange part 14 Electrode board group 15 Recess 16 Step part 47 Positive electrode plate 48 Negative electrode plate 49 Separator 50 Frame body 51 Resin sheet 52 Insertion jig

Claims (4)

An electrode plate group in which a positive electrode plate and a negative electrode plate are wound flatly through a separator is accommodated in a concave portion of a main body case in which a joint portion is formed in an opening of a rectangular half-shell, and a concave portion of the main body case is formed. A prismatic battery formed by closing and sealing the inside of the recess by welding a lid plate closed and placed on the joint to the joint.
The electrode plate group, the width in the direction perpendicular to the winding direction, the positive electrode plate and the negative electrode plate is smaller than the recess width dimension, the separator Ri Na is formed larger than the width dimension in the recess,
A recess is formed on the lid plate toward the inside of the recess with a position away from the inner peripheral wall of the recess of the main body case as an outer peripheral wall, and the outer dimension is between the outer peripheral wall of the recess and the inner peripheral wall of the recess. A prismatic battery comprising: an insulating frame that is smaller than a width dimension and has an inner dimension larger than the width dimension of a positive electrode plate and a negative electrode plate . An electrode plate group in which a positive electrode plate and a negative electrode plate are wound flatly through a separator is accommodated in a concave portion of a main body case in which a joint portion is formed in an opening of a rectangular half-shell, and a concave portion of the main body case is formed. In the method of manufacturing a rectangular battery that closes and welds the lid plate placed on the joint to the joint and seals the inside of the recess,
The electrode plate group has a width in a direction perpendicular to the winding direction, the positive electrode plate and the negative electrode plate are formed to be smaller than the inner width dimension of the recess, and the separator is formed to be larger than the inner width dimension of the recess. a by inserting the end edges of the separator folded in the inserting direction downstream side, with the positive and / or negative electrode plate end portion and the manufacturing method of Unishi was square-shaped battery by you interposed between the recess wall of There,
When inserting the electrode plate group into the recess, insert a resin film between at least the side surface perpendicular to the winding direction of the electrode plate group and the inner wall of the recess, and heat and soften the part of the resin film protruding outside the recess A method of manufacturing a prismatic battery , comprising: bending and shaping on the electrode plate group together with the edge of the folded separator . The method for producing a prismatic battery according to claim 2 , wherein the resin film is a material whose softening temperature is lower than the melting temperature of the separator. The electrode plate group in which the positive electrode plate and the negative electrode plate are wound flatly via a separator is accommodated in the recess of the main body case in which a joint is formed in the opening of the quadrangular half-shell, and the main body case has a recess. In the method of manufacturing a rectangular battery that closes the lid and welds the lid plate placed on the joint to the joint to seal the inside of the recess,
The electrode plate group has a width in a direction perpendicular to the winding direction, the positive electrode plate and the negative electrode plate are smaller than the concave inner width dimension, and the separator is larger than the concave inner width dimension,
By inserting the electrode plate group into the recess through an insertion jig formed in a frame shape whose outer dimension is smaller than the width of the inner wall of the recess and whose inner dimension is larger than the width of the positive and negative plates, the insertion jig A method of manufacturing a rectangular battery, wherein the electrode plate group is inserted into the recess with the end of the separator bent in the insertion direction downstream side.

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