Patent Application
20150030935
The present invention relates to a battery electrode substrate sheet used for a battery electrode.
A positive electrode used in a battery, for example, a lithium ion secondary battery is produced by forming, in a predetermined thickness, a coating layer of a positive electrode active material on an aluminum foil. Similarly, a negative electrode is produced by forming a coating layer of a negative electrode active material on a copper foil.
Presence of an abnormality in thickness, such as ruggedness, or coating unevenness in the coating layer of the metal foil significantly affects battery characteristics. In order to cope with this, a detection means such as an image pickup device or a non-contact film thickness instrument is used to detect a defective part in a continuous manner.
There is proposed a battery electrode manufacturing system provided with a marking means for putting a start point mark on a metal foil at a position corresponding to a start point of a coated region where a measured film thickness goes out of a prescribed range and putting an endpoint mark on the metal foil at a position corresponding to an end point of the coated region where the measured thickness goes out of the prescribed range. At production of an electrode, an electrode punching means is used to punch the metal foil excluding an area from the starting point mark to the end point mark (refer to, for example, Patent Document 1).
[Patent Document 1] JP2011-134479A
As described in the invention disclosed in Patent Document 1, by indicating apart of the coating layer of the electrode active material at which the thickness unevenness exists, it is possible to exclude the part including the thickness unevenness in producing the battery electrode; however, there exists the following problem.
There is formed a defect sign part 105a with its leading end aligned with an extension line extending, in a width direction of a strip-shaped collector, from an end portion of the coating unevenness 104a on a leading end side of the collector up to a position exceeding the positive electrode active material coating layer and its rear end aligned with an extension line extending, in the width direction of the collector, from an end portion of the coating unevenness 104a on a rear end side of the collector up to a position exceeding the positive electrode active material coating layer.
Subsequently, an insulating protective film 107 is formed on the positive electrode collector 101 in a longitudinal direction of the collector along the positive electrode active material coating layer 103. It is necessary to provide a predetermined gap between the defect sign part 105a and insulating protective film 107 in order to prevent mutual interference between them, so that an increase in a width of the collector cannot be avoided.
A portion located outward of the insulating protective film 107 is an unnecessary portion as a battery electrode, excluding a portion where a positive electrode lead tab is formed, so that an amount of the collector to be discarded is increased. In addition, two processing steps of formation of the defect sign part and formation of the insulating protective film are required for detection of the thickness unevenness.
The above problems can be solved by a battery electrode substrate sheet including a strip-shaped collector, an electrode active material coating film formed on the collector in a longitudinal direction thereof, and an insulating protective film formed on an electrode active material non-coating surface of the collector so as to extend along the coating film in the longitudinal direction thereof, wherein a defect sign part that indicates a portion at which a defective part of the coating film exists is formed on the insulating protective film.
Further, in the battery electrode substrate sheet, a leading end of the defect sign part is disposed on an extension line extending, in a width direction of the collector, from a leading end of the defect part in a length direction of the collector, and a rear end of the defect sign part is disposed on an extension line extending, in the width direction of the collector, from a rear end of the defect part in the length direction of the collector.
In the battery electrode substrate sheet, the insulating protective film is continuously formed, excluding the defect sign part.
In the battery electrode substrate sheet, the insulating protective film is provided only at an electrode lead tab of a unit electrode forming part to be produced, and the defect sign part is provided in the electrode lead tab forming part belonging to a unit electrode forming part in which the defect part exists on the coating part.
In the battery electrode substrate sheet, both sides of a width direction center line of the coating film coated on the collector are independent of each other, each of the both sides includes the defect sign part corresponding to the defect part existing in itself, and when the defect part exists on the center line, the defect sign part is formed on the both sides of the center line.
In the battery electrode substrate sheet, on at least one of front and back side surfaces of the collector, the defect sign part corresponding to the defect part on the opposite side is also formed at a position symmetrical to the defect part on the opposite side with respect to a center surface of the collector in a thickness direction thereof.
In the battery electrode substrate sheet, the defect sign part is formed as a portion at which the insulating protective film is not coated or formed by intermittently coating characters, marks, or insulating protective film.
In the battery electrode substrate sheet, the insulating protective film is an ultraviolet curing composition formed by an inkjet coating means.
In the battery electrode substrate sheet, a plurality of rows of the electrode active material coating films are formed on the collector so as to extend in the longitudinal direction thereof with a predetermined interval provided therebetween.
The battery electrode substrate sheet is used for a lithium ion battery electrode.
The battery electrode substrate sheet is used for a positive electrode.
According to the battery electrode substrate sheet of the present invention, the defective part existing in the coating film obtained by coating the electrode active material on the collector is indicated using a formation part of the insulating protective film formed on the electrode active material non-coating surface of the collector. Thus, it is possible to reduce a size of a part of the collector that is not used as a battery electrode and to easily identify the defect sign part using a defect identification device or by a visual observation.
Hereinafter, a battery electrode substrate sheet according to the present invention will be described with reference to the drawings.
In a battery electrode substrate sheet 100 illustrated in
There is formed a defect sign part 105a with its leading end aligned with an extension line extending, in a width direction of a strip-shaped collector, from a leading end portion of the coating unevenness 104a in a longitudinal direction of the collector up to a position exceeding the positive electrode active material coating layer and its rear end portion aligned with an extension line extending, in the width direction of the collector, from an end portion of the coating unevenness 104a in the longitudinal direction of the collector up to a position exceeding the positive electrode active material coating layer.
The defect sign part 105a illustrated in
With this configuration, the defect sign part 105a can be identified by presence/absence of the insulating protective film 107, whereby there can be provided a battery electrode substrate sheet that does not require an additional member for forming the defect sign part 105a.
Coating unevennesses 104a and 104b exist in the positive electrode active material coating layer 103 formed on the positive electrode collector 101.
In
Unit electrodes 110a and 110b, each in which a leading end portion or a rear end portion of a coating unevenness 104a or 104b in the longitudinal direction of the collector exists, include defect sign parts 105a and 105b, respectively, which are provided by not forming the insulating protective film.
In the example of
Further, in the battery electrode substrate sheet of the example, the insulating protective film is formed only in a length corresponding to a lateral width of the electrode lead tab, which saves a use amount of a raw material of the insulating protective film.
In the battery electrode substrate sheet 100 illustrated in
In addition to the coating unevennesses 104a and 104b, a coating unevenness 104c exists on a longitudinally-extending center line 102 of the coating layer. Thus, there are formed defect sign parts 105a and 105b with their leading end portions aligned with extension lines extending, in the width direction of the collector, from leading end portions of the respective coating unevennesses 104a and 104b in the longitudinal direction of the collector up to positions exceeding the positive electrode active material coating layer and their rear end portions aligned with extension lines extending, in the width direction of the collector, from rear end portions of the respective coating unevennesses 104a and 104b in the longitudinal direction of the collector up to positions exceeding the positive electrode active material coating layer. In addition, defect sign parts 105c1 and 105c2 are each provided by forming a portion where the insulating protective film 107 is absent. The defect sign parts 105c1 and 105c2 are each positioned on the insulating protective film 107 continuously formed along the outer edge portion on each of both sides of the positive electrode active material coating layer 103 at a portion corresponding to an extension of the coating unevenness 104c on the center line 102 in the width direction.
The insulating protective film 107 is formed between the outer edge portion of the positive electrode active material coating layer 103 and electrode lead tab forming part 108.
In addition to the coating unevennesses 104a and 104b, a coating unevenness 104c exists in the positive electrode active material coating layer 103 formed on the positive electrode collector 101. The unit electrode 110a in which the leading end portion or rear end portion of the coating unevenness 104a in the longitudinal direction of the collector exists includes a defect sign part 105a, which is provided by not forming the insulating protective film.
Further, a part of the coating unevenness 104c exists on the longitudinally-extending center line 102. Thus, defect sign parts 105c1 and 105c2, which are provided by not forming the insulating protective film, are provided at the outer edge of the positive electrode active material coating layer 103.
With the above configuration, it is possible to eliminate all the electrode units that have the coating unevenness at manufacturing time of the battery electrode, irrespective of the position of the coating unevenness.
In the above description, the defect sign part for indicating the coating unevenness existing on one surface of the battery electrode substrate sheet has been described. However, in the battery electrode substrate sheet, the positive electrode active material coating layer 103 is formed on both front and back side surfaces of the collector. A problem occurs in characteristics of the battery electrode even when the coating unevenness exists only on one surface, so that it is important to check a state of both side surfaces of the battery electrode substrate sheet.
Thus, it is preferable to form, at least on one of the front and back side surfaces, both the defect sign part for one side surface and that for the other side surface. That is, it is preferable to form, at least on one of the front and back side surfaces, the defect sign parts corresponding to all the coating unevennesses on both front and back side surfaces.
The positive electrode collector 101 of the battery electrode substrate sheet 100 illustrated in
There are formed defect sign parts 105a and 105b with the end portions of each of the defect sign parts 105a and 105b aligned with extension lines extending, in the width direction of the collector, from end portions of the respective coating unevennesses 104a and 104b in the longitudinal direction of the collector up to positions exceeding the positive electrode active material coating layer. In addition, a projected part 104d is obtained by projecting a coating unevenness existing on the back side surface to the positive electrode active material coating layer, and there is formed a defect sign part 105d with the end portions thereof aligned with extension lines extending, in a width direction of the collector, from the end portions of the projected part 104d in a longitudinal direction of the collector up to a position exceeding the positive electrode active material coating layer.
Unit electrodes 110a and 110b, in which coating unevenness 104a and 104b exist, respectively, include defect sign parts 105a and 105b, respectively, which are provided by not forming the insulating protective film. In addition, a unit electrode 110d, in which a projected part 104d obtained by projecting a coating unevenness existing on the back side surface to the positive electrode active material coating layer, includes a defect sign part 105d which is formed by not forming the insulating protective film.
As described above, the defect sign parts corresponding to all the coating unevennesses on both front and rear side surfaces are formed at least on one of the front and back side surfaces, so that it is possible to produce a battery electrode having no defective part by checking only one surface at cutting out of the electrode from the battery electrode substrate sheet.
A coating film is obtained by coating, in a predetermined thickness, the electrode active material on both surfaces of the collector made of a strip-shaped metal foil, followed by drying, and then, a roll is used to press the obtained coating film to obtain the battery electrode substrate sheet 100. Then, while moving the obtained battery electrode substrate sheet 100 at a constant speed, various defects in the active material layer 103, such as an abnormality in thickness (ruggedness), coating unevenness, discoloration are continuously detected by means of a detection means 301 such as an image pickup device or a non-contact film thickness instrument.
A detection signal including leading end position information and rear end position information of the defective part detected by the detection means 301 is transmitted to a controller 303.
Based on the detection signal, the controller 303 transmits, to an insulating protective film forming device 305 provided with a coating device, a predetermined operation signal after elapse of a time calculated from a moving speed of the battery electrode substrate sheet to make the insulating protective film forming device 305 form a coating film on an area excluding a portion where the defective part is detected. After that, an ultraviolet curing device 306 is used to irradiate the coating film with ultraviolet ray to form the insulating protective film 107.
Further, the controller 303 stores unique information including identification information of the battery electrode substrate sheet and distance information thereof from a reference point to the leading and rear ends of the defective part in an information recording device 307, as well as, in an information recording medium 309.
Various coating devices can be used as the insulating protective film forming device 305. When a non-contact coating device such as an inkjet coating device is used, accurate coating can be easily performed.
After formation of the insulating protective film, the manufacturing step of the battery electrode substrate sheet 100 is shifted to a cutting step of cutting the battery electrode or a shipping step. At this time, the unique information including defect position information of the battery electrode substrate sheet is transmitted, via a communication line or information recording medium 309, to the battery electrode cutting step, whereby the battery electrode having no defective part can be accurately cut.
A coating film is obtained by coating the electrode active material on both surfaces of the collector, followed by drying, and then, a roll is used to press the obtained coating film to obtain the battery electrode substrate sheet 100. Then, while moving the obtained battery electrode substrate sheet 100 at a constant speed, various defects in the active material layer 103, such as an abnormality in thickness (ruggedness), coating unevenness, discoloration on a first surface are continuously detected by means of a first detection means 301a such as an image pickup device or a non-contact film thickness instrument. At the same time, the above detection is performed also for an active material layer 105 on a second surface which is the opposite surface of the battery electrode by using a second detection means 301b.
A detection signal including leading end position information and rear end position information of the defective part detected by the first or second detection means 301a or 301b is transmitted to the controller 303.
Based on the detection signal from the first detection means 301a, the controller 303 transmits, to a first insulating protective film forming device 305a provided with a non-contact coating device such as an ink-jet coating device, a predetermined operation signal after elapse of a time calculated from the moving speed of the battery electrode substrate sheet to make the first insulating protective film forming device 305a form a coating film on an area excluding a portion where the defective part is detected. After that, an ultraviolet curing device 306a is used to irradiate the coating film with ultraviolet ray to form the insulating protective film 107.
Further, the controller 303 reverses a travel direction of the battery electrode substrate sheet that has passed through the first insulating protective film forming device 305a using a reversing pulley. Then, based on the detection signal from the second detection means 301b, the controller 303 transmits, to a second insulating protective film forming device 305b provided with a non-contact coating device such as an ink-jet coating device, a predetermined operation signal after elapse of a time calculated from the moving speed of the battery electrode substrate sheet to make the second insulating protective film forming device 305b apply an insulating protective film forming material on the second surface which is the opposite surface to the surface where the insulating protective film has already been formed. After that, an ultraviolet curing device 306b is used to irradiate the coating film with ultraviolet ray to form the insulating protective film 107.
In the above description, the defect sign part is formed on one surface of the battery electrode substrate sheet. However, a configuration may be possible in which the defect sign part is formed on one surface, as well as, on the opposite surface which is a surface symmetrical to the one surface with respect to a center surface in the thickness direction of the collector.
That is, when the first detection means 301a detects a defective part, the controller 303 transmits also to the second insulating protective film forming device 305b, a signal indicating presence of the defective part together with the defect position information, thus preventing the insulating protective film from being formed.
Similarly, when the second detection means 301b detects a defective part, the controller 303 transmits also to the first insulating protective film forming device 305a, a signal indicating presence of the defective part, thus preventing the insulating protective film from being formed.
As described above, by reflecting a detection result of one surface and a detection result of the other surface on each other, it is possible to form, for one defective part such as the coating unevenness existing on one surface, the defect sign part in which the insulating protective film is absent also on the opposite surface which is a surface symmetrical to the one surface with respect to a center surface in the thickness direction of the collector.
After formation of the insulating protective film, the manufacturing step of the battery electrode substrate sheet 100 is shifted to a cutting step of cutting the battery electrode or a shipping step. At this time, the unique information including the defect position information of the battery electrode substrate sheet is transmitted, via a communication line or information recording medium 309, to the battery electrode cutting step, whereby the battery electrode having no defective part can be accurately cut.
By thus printing the marks or characters, the defect sign part can be reliably visually recognized even if an abnormality occurs in the insulating protective film forming device to generate a portion where the insulating protective film is not formed.
In the above description, the coating film is formed in one row on the collector in the longitudinal direction thereof. Alternatively, however, a plurality of rows of coating films may be formed on the collector in the longitudinal direction thereof so as to extend in parallel to one another.
Two rows of positive electrode active material coating layers 103a and 103b are formed on the collector 101 of the battery electrode substrate sheet 100. Defect sign parts 105a, 105b, and 105c corresponding respectively to coating unevennesses 104a, 104b and a projected part 104c of the coating unevenness on the back side surface are formed on the insulating protective film 107 which is formed on the electrode active material non-coating surface of the collector so as to extend along both sides of the coating layer 103a in the longitudinal direction thereof.
Further, defect sign parts 105d, 105e, and 105f corresponding respectively to a projected part 104d of the coating unevenness on the back side surface and coating unevennesses 104e, 104f are formed on the insulating protective film 107 which is formed on the electrode active material non-coating surface of the collector so as to extend along both sides of the coating layer 103b in the longitudinal direction thereof.
By thus forming the two rows or more rows of the coating films, production efficiency of the electrode can be improved.
As illustrated in
As illustrated in
As illustrated in
The outer edge of the positive electrode active material layer of the positive electrode lead tab 108 of the unit positive electrode 115 is coated with the insulating protective film 107, so that even if the separator contracts, it is possible to prevent the positive electrode lead tab 108 of the unit positive electrode 205 from being short-circuited with the negative electrode 210 which is larger in area than the positive electrode 115.
In the battery electrode substrate sheet according to the present invention, the defective part existing in the coating film obtained by coating the electrode active material on the collector is indicated using a formation part of the insulating protective film formed on the electrode active material non-coating surface of the collector. Thus, battery electrodes each having no defective part can be cut out effectively and, thus, a battery electrode excellent in characteristics can be provided.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-070612 | Mar 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/052894 | 2/7/2013 | WO | 00 |
