CN117413430A - Method for manufacturing electrode of secondary battery, and electrode manufacturing system for use in the method - Google Patents
Method for manufacturing electrode of secondary battery, and electrode manufacturing system for use in the method Download PDFInfo
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- Battery Electrode And Active Subsutance (AREA)
Abstract
The present invention provides a method of manufacturing an electrode of a secondary battery, and an electrode manufacturing system used in the above method, the method including the steps of: (a) Preparing an electrode sheet including a current collector divided into a coated portion and a non-coated portion and having an insulating layer laminated on the non-coated portion; and (b) forming an electrode tab by slitting a non-coated portion having an insulating layer laminated thereon, wherein a laminate having a thickness of 100ps to 10ps is used ‑6 The laser of the pulse width ps performs the kerf.
Description
Technical Field
The present application claims the benefit of priority based on korean patent application nos. 10-2021-0142521 filed on 25 th 10 th 2021 and 10-0136851 filed on 21 th 2022, the entire contents of which are incorporated herein by reference.
The present invention relates to a method of manufacturing an electrode of a secondary battery, and an electrode manufacturing system used in the above method.
Background
As the demand for automobiles and portable devices increases, the demand for secondary batteries as an energy source increases rapidly. In particular, lithium secondary batteries having high energy density and high discharge voltage among secondary batteries have been commercialized and widely used.
As for the shape of a battery among lithium secondary batteries, there is a demand for prismatic secondary batteries and pouch-type secondary batteries that can be applied to mobile phones and automobiles, and as for materials, there is a higher demand for lithium secondary batteries such as lithium ion batteries and lithium ion polymer batteries that have advantages such as high energy density, high discharge voltage, and high output stability.
Lithium secondary batteries are also classified according to the structure of an electrode assembly of a positive electrode/separator/negative electrode structure. Specifically, the following electrode assemblies are known: jelly-roll (wound) electrode assembly having a structure in which a long sheet-type positive electrode and a long sheet-type negative electrode are wound with a separator interposed therebetween; a stacked electrode assembly in which a plurality of positive electrodes and negative electrodes cut into units of a predetermined size are sequentially stacked with a separator interposed therebetween; and a stacked/folded electrode assembly of a Bi-cell (Bi-cell) or a Full cell (Full cell) stacked with a separator interposed therebetween and a separator sheet wound, etc. of a predetermined unit.
Recently, a pouch-type battery having a structure in which a stacking-type or stacking/folding-type electrode assembly is built in a pouch-type battery case of an aluminum laminate sheet has been receiving much attention due to reasons such as low manufacturing costs, light weight, and easy deformation of shape, and its use has also been increasing.
In addition, the stacked-type electrode assembly or the stacked/folded-type electrode assembly has a structure in which a separator is laminated in a state in which it is interposed between a positive electrode and a negative electrode having electrode tabs protruding on one side. In the case of such a structure, if the temperature rises due to exposure to an external heat source or an internal short circuit, there is a case where some of the positive electrode and the negative electrode may come into contact and cause a short circuit while the separator is contracted. Therefore, in order to prevent these problems, a technique of forming an insulating layer on the positive electrode tab portion and/or the negative electrode tab portion has been introduced, as shown in fig. 1.
The technique of forming the insulating layer for the electrode tab improves the safety and reliability of the battery, but also results in an increase in the number and difficulty of the steps of forming the electrode tab.
[ Prior Art literature ]
Korean patent laid-open No. 10-2015-0098445
Disclosure of Invention
Technical problem
The inventors of the present invention have studied an effective dicing process of an electrode tab having an insulating layer laminated thereon while applying a laser dicing method. However, it has been confirmed that problems such as re-fusion of the melted insulating layer after cutting, generation of scum (dross) at the time of separating the re-fused portions, poor appearance of the electrode tab due to re-fusion, lifting (or cracking) of the insulating layer due to melting and curling phenomena of the insulating layer, and exposure of a portion of the current collector due to lifting of the insulating layer are generated due to very narrow line width of the cut line of the laser.
The inventors of the present invention have been made an attempt to solve the above-mentioned problems, and as a result, have found a way of preventing the occurrence of the above-mentioned problems by minimizing melting of the insulating layer during cutting, and have completed the present invention.
An object of the present invention is to provide a method of manufacturing an electrode of a secondary battery capable of manufacturing an electrode including an electrode tab having an insulating layer laminated thereon with excellent efficiency and excellent quality by using a specific laser.
Further, an object of the present invention is to provide an electrode for a secondary battery having an electrode tab laminated with an insulating layer, the electrode tab having an excellent cut profile.
Furthermore, it is an object of the present invention to provide an electrode manufacturing system for use in the above method.
Technical proposal
In order to achieve the above object, the present invention provides:
a method of manufacturing an electrode of a secondary battery, comprising the steps of:
(a) Preparing an electrode sheet including a current collector divided into a coated portion and a non-coated portion and having an insulating layer laminated on the non-coated portion; and
(b) The electrode tab is formed by cutting the non-coated portion on which the insulating layer is laminated,
wherein a composition having 100ps to 10 -6 The laser of pulse width ps performs the kerf.
Furthermore, the present invention provides:
an electrode for a secondary battery, comprising: a laser-cut electrode tab cut in a state that an insulating layer and a current collector are laminated,
wherein the thickness of the cut section of the electrode tab is 1 to 1.7 times the thickness before cutting.
Furthermore, the present invention provides:
an electrode for a secondary battery, comprising: a laser-cut electrode tab cut in a state that an insulating layer and a current collector are laminated,
wherein in a cut section of the electrode tab, a length of the current collector protruding from the front end of the insulating layer is less than 20 μm.
Furthermore, the present invention provides:
an electrode manufacturing system, comprising:
an electrode sheet supply device for supplying an electrode sheet, the electrode sheet supply device including a current collector divided into a coated portion and a non-coated portion and having an insulating layer laminated on the non-coated portion;
a laser beam irradiation device which irradiates a laser beam having a wavelength of 100ps to 10ps -6 A laser beam of a pulse width ps to form an electrode tab by notching the non-coated portion on which the insulating layer is laminated; and
a jig for supporting a portion of the electrode sheet irradiated with the laser beam on a lower surface.
Advantageous effects
The electrode manufacturing method of the present invention is achieved by providing a substrate having a thickness of 100ps to 10 -6 Application of ps pulse width laser to the dicing process of the electrode tab having the insulating layer laminated thereon provides an effect of greatly improving the electrode manufacturing efficiency and electrode quality, thus preventing problems such as re-fusion of the insulating layer after dicing, generation of scum when separating the re-fused portions, poor appearance of the electrode tab due to re-fusion, lifting (or splitting) of the insulating layer due to melting and curling phenomena of the insulating layer, and exposure of the current collector due to lifting of the insulating layerThe questions are given.
In addition, the electrode of the present invention provides an excellent electrode tab profile laminated with an insulating layer, thereby providing an effect of improving stability and reliability of the battery.
Further, the electrode manufacturing system of the present invention provides an electrode manufacturing system capable of effectively performing the above-described method.
Drawings
Fig. 1 is a partial cross-sectional view of a battery structure including a stacked electrode having an electrode tab with an insulating layer stacked thereon.
Fig. 2 is a plan view showing the shape of an electrode sheet in a previous stage of a slitting process of the electrode tab in the process of manufacturing an electrode in which an insulating layer is laminated on the electrode tab.
Fig. 3 is an enlarged view of a portion a of fig. 2.
Fig. 4 is a diagram visually showing characteristics of a laser used in the present invention.
Fig. 5 is a graph showing peak power according to pulse width of laser light.
Fig. 6 is a diagram schematically showing an electrode manufacturing system according to an embodiment of the present invention.
Fig. 7 is a photograph of a state in which the insulating layer is ruptured on the cut surface when the electrode tab laminated with the insulating layer is cut using a nanosecond laser.
Fig. 8 is a photograph showing a state in which dross (dross) in the form of a thread-end appears on a cut surface when the insulating layer laminated electrode tab is cut using a die.
Detailed Description
Hereinafter, the present invention will be described in detail with reference to the drawings of embodiments of the present invention so that those skilled in the art can easily implement the present invention. This invention may, however, be embodied in many different forms and is not limited to the embodiments described herein. Throughout this application, similar parts are assigned the same reference numerals.
When a certain element is referred to as being "connected to, disposed on, or mounted on" another element, it should be understood that the element may be directly connected to or mounted on the other element but other elements may be present therebetween. On the other hand, when referring to a certain component as being "directly connected to, directly provided with, or directly mounted on" another component, it is understood that there are no other components in between. In addition, other expressions describing the relationship between elements such as "on top" and "directly on top", or "between … …" and "directly between … …", or "adjacent" and "directly adjacent" should be interpreted similarly.
The method of manufacturing an electrode of a secondary battery of the present invention includes:
(a) Preparing an electrode sheet including a current collector divided into a coated portion and a non-coated portion and having an insulating layer laminated on the non-coated portion; and
(b) The electrode tab is formed by cutting a non-coated portion on which an insulating layer is laminated,
wherein a composition having 100ps to 10 -6 The laser of pulse width ps performs the kerf.
If the pulse width exceeds 100ps, side effects due to heat may occur, if the pulse width is less than 10 -6 ps is undesirable in terms of cost.
The pulse width may be selected from a range of, for example, picoseconds (picoseconds), femtoseconds (Femtosecond), and the like, and may be used in a range of 100ps to 100 fs.
In the conventional electrode manufacturing method, a method of applying a laser device to a slit of an electrode tab on which an insulating layer is not laminated has been introduced. However, the slit of the electrode tab on which the insulating layer is not laminated and the slit of the electrode tab on which the insulating layer is laminated have a large difference in slit materials. Therefore, when considering the efficiency of the slitting process and the quality of the manufactured electrode tab, applying the conventional laser method as it is to the slitting of the electrode tab on which the insulating layer is laminated seems to be an undesirable option. That is, when the electrode tab laminated with the insulating layer is notched (or cut), the characteristics of the material of the insulating layer have a great influence on the efficiency of the notching process or the quality of the notched electrode tab, and thus the conventional notching process, on which the electrode tab laminated with no insulating layer is applied as it is, has a significant limitation in terms of efficiency or quality.
In particular, when the conventional laser application technique was applied to the dicing of the insulating layer-laminated electrode tab, it was confirmed that the efficiency of the dicing process and the quality of the diced electrode tab were greatly reduced due to the melting problem of the insulating layer. That is, when a conventional laser technique using heat absorption of a dicing medium and a dicing mechanism of the medium thus produced is applied to dicing of an electrode tab of an insulating layer laminate, there is a problem in that the melted insulating layer is re-fused during dicing while the characteristics of laser dicing having a line width of a very narrow dicing line and the characteristics of the insulating layer melted by absorbing the laser wavelength co-act. Further, when separating the re-fused portions, there are also problems in that the outer shape of the cut surface becomes uneven, scum (dross) is generated, for example, the melted insulator gathers into soft pieces, the insulating layer is lifted (or cracked) due to melting and curling of the insulating layer, and a part of the current collector is exposed due to the above-described lifting phenomenon. In addition, the profile of the cross section of the electrode tab shows a high defect rate.
Therefore, in order to solve the above-mentioned problems, the present invention is characterized in that a device having a pressure of 100ps to 10 -6 ps.
As confirmed by various experiments, the present inventors have found that the above problems occur even when a pulse laser and a continuous wave (cw) laser conventionally used in the dicing process are used. However, if 100ps to 10 are used among the pulse lasers -6 The above problem seems to be avoided by the laser of the pulse width ps, and the effect of greatly improving the kerf velocity can be obtained. That is, even if nanosecond (nanosecond) laser light outside the scope of the present invention is used, problems due to melting of the insulating layer occur, but if laser light having a pulse width of picoseconds or less (a pulse width of 100ps or less) is used, the above-described problems do not occur.
This difference appears to be due to the laser cutting mechanism, as shown in fig. 4. That is, as shown in fig. 4, in the case of nanosecond laser, a region affected by heat absorption is generated in the cut material, and if the insulating layer is located in the region, the insulating layer melts and causes the problems as described above.
However, if a laser having a pulse width of picoseconds (a pulse width of 100ps or more) is used, since an atomic bond is broken before sufficient energy is transferred to an atom, it can be cut in a cold state without heat input, thereby avoiding a thermal problem.
In one embodiment of the present invention, a device having 10ps to 10 can be effectively used -3 ps or 5ps to 10 -1 ps. This is because a laser having a pulse width in the above range may be practical when considering costs and the like, since the desired effect in the present invention can be obtained even if the pulse width is not smaller.
In one embodiment of the present invention, although light of wavelengths in Infrared (IR), ultraviolet (UV), and green regions may be used for the laser, IR may be preferably used in consideration of stability and usability of the laser.
In one embodiment of the present invention, as the laser light, a laser light having an average power energy of 10W to 200W based on an average traveling speed of 100mm/s to 2000mm/s, a laser light having an average power energy of 20W to 150W based on an average traveling speed of 500mm/s to 1500mm/s, or a laser light having an average power energy of 50W to 100W based on an average traveling speed of 1000mm/s may be used.
In one embodiment of the present invention, the average advancing (cutting) speed during the incision may be 100mm/s to 2000mm/s, and may be preferably 500mm/s to 1500mm/s in terms of the incision efficiency.
The above-described laser average power energy and average traveling speed are examples of one embodiment of the present invention, but the present invention is not limited thereto. The average power may be appropriately changed according to circumstances such as the configuration of the laser optical system and the light collecting capability of the lens, and the average traveling speed may be appropriately changed according to circumstances such as the shape of the cut object.
In one embodiment of the present invention, the insulating layer may include a polymer resin. The insulating layer may further comprise, in addition to the polymer, a material selected from boehmite (AlO (OH)), al 2 O 3 、γ-AlOOH、Al(OH) 3 、Mg(OH) 2 、Ti(OH) 4 、MgO、CaO、Cr 2 O 3 、MnO 2 、Fe 2 O 3 、Co 3 O 4 、NiO、ZrO 2 、BaTiO 3 、SnO 2 、CeO 2 、Y 2 O 3 、SiO 2 At least one inorganic particle of the group consisting of silicon carbide (SiC) and Boron Nitride (BN).
Furthermore, at least one material for the insulating layer in this field may be included in addition to the above-described components.
In the above, the weight ratio of the polymer (binder) and the inorganic particles included in the insulating layer may be 5:95 to 99: 1. 5:95 to 50:50. or 10:90 to 50:50.
the polymer resin may be at least one selected from the group consisting of styrene-butadiene rubber, acrylate styrene-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluoro rubber, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polypropylene oxide, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene-diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, hydroxypropyl methylcellulose, hydroxypropyl cellulose, diacetyl cellulose, and the like.
In one embodiment of the present invention, the electrode sheet is not particularly limited, but may include, for example, a current collector having a thickness of less than 30 μm and an insulating layer having a side thickness of less than 40 μm.
In one embodiment of the present invention, the electrode sheet may be an electrode sheet in which an active material is laminated on the coating portion or an active material is not laminated. Typically, the active material is used in a laminated state, but is not limited thereto.
In one embodiment of the invention, the electrode may be a positive electrode or a negative electrode. The current collector for the positive electrode or the negative electrode may be a foil made of copper, aluminum, gold, nickel, copper alloy, or a combination thereof, but is not limited thereto. In particular, in the present invention, the electrode may be a positive electrode, and an aluminum (Al) foil may be used as a current collector.
In the method of manufacturing the electrode of the secondary battery, methods known in the art may be employed without limitation, other than the above description.
Furthermore, the invention relates to:
an electrode for a secondary battery, comprising: a laser-cut electrode tab having an insulating layer and a current collector cut in a laminated state,
wherein the thickness of the cut section of the electrode tab is 1 to 1.7 times the thickness before cutting.
The laser may be 100ps to 10 -6 ps.
In the conventional electrode including the laser-cut electrode tab having the insulating layer and the current collector cut in the laminated state, the warpage (or cleavage) of the insulating layer is very large due to melting and curling of the insulating layer, as shown in fig. 7. The profile of the cross section of the electrode tab causes a short circuit, thereby causing a battery failure.
By solving the above-described problems, the electrode of the present invention has a feature of minimizing the warpage (or cracking) of the insulating layer.
In the above, the thickness of the cut section of the electrode tab may be 1 to 1.6 times the thickness before cutting. Further, the lower limit may be 1.1 times, 1.2 times, 1.3 times, 1.4 times, or 1.5 times.
Further, as shown in fig. 8, the cut section of the electrode tab of the present invention has a feature of excluding dross (dross) in the form of a thread end, which is inevitably generated when cutting with a die.
Furthermore, the invention relates to:
an electrode for a secondary battery, comprising: a laser-cut electrode tab having an insulating layer and a current collector cut in a laminated state,
wherein in a cut section of the electrode tab, a length of the current collector protruding from the front end of the insulating layer is less than 20 μm.
The laser may be 100ps to 10 -6 ps.
In the conventional electrode including the laser-cut electrode tab having the insulating layer and the current collector cut in the laminated state, because of the characteristic that the insulating layer is cut while absorbing the laser wavelength and melting, the insulating layer generates very large warpage (or cracks) due to melting and curling of the insulating layer, as shown in fig. 7. In addition, the occurrence of such a lift-up phenomenon causes the current collector to be exposed. The exposed current collector causes a short circuit or the like, thereby causing a battery failure.
By solving the above-described problems, the electrode of the present invention has a feature of minimizing the exposure of the current collector.
In the present invention, the length of the protruding current collector may have an upper limit of less than 18 μm or less than 16 μm. Further, the lower limit may be 0,1 μm, 3 μm, 5 μm, 10 μm, 12 μm, or 15 μm.
Further, as shown in fig. 8, the cut section of the electrode tab of the present invention has a feature of excluding dross (dross) in the form of a thread end, which is inevitably generated when cutting with a die.
Furthermore, the invention relates to:
an electrode manufacturing system, comprising: an electrode sheet supply device 200 for supplying an electrode sheet including a current collector divided into a coated portion and a non-coated portion and having an insulating layer 11 laminated on the non-coated portion 12, as shown in fig. 6;
a laser beam irradiation apparatus 300, the laser beam irradiation apparatus 300 irradiating a laser beam having a wavelength of 100ps to 10ps -6 A laser beam of a pulse width ps to form an electrode tab by notching a non-coated portion on which the insulating layer 11 is laminated; and
and a jig 400 for supporting a portion of the electrode sheet irradiated with the laser beam on a lower surface of the jig 400.
All information related to the above-described electrode manufacturing method can be applied to the system of the present invention. Therefore, a description of the overlapped contents will be omitted below.
In one embodiment of the present invention, the electrode sheet supply apparatus 200 may be a Roll-to-Roll (Roll-to-Roll) apparatus. At this time, the roll-to-roll apparatus may be of the form shown in fig. 8, and may further include an unwinding roller and a rewinding roller on both sides, which is a configuration not shown in fig. 8.
In one embodiment of the present invention, the laser beam irradiation apparatus 300 emits a laser beam having a wavelength of 100ps to 10 -6 The laser beam irradiation apparatus 300 may have the same configuration as a commercially available general laser apparatus except for a laser beam of a pulse width ps.
For example, the laser beam irradiation apparatus 300 may include a laser source generator, a transmission mirror (delivery mirror), a laser beam width adjuster, and a scanner unit, and the scanner may include a galvanometer mirror, a θ lens (e.g., F- θ lens), and the like.
In one embodiment of the present invention, the structure of the jig 400 is not particularly limited as long as it can support the portion of the electrode sheet irradiated with the laser beam on the lower surface. For example, as shown in fig. 8, a device designed to support electrode sheets while rotating the electrode sheet support portion 410 configured in plurality may also be used.
Mode for carrying out the invention
Hereinafter, the present invention will be described in detail by way of illustration to explain the present invention in detail. However, the embodiments according to the present invention may be modified in many different forms, and the scope of the present invention should not be construed as being limited to the examples described in detail below. The examples of the present invention are provided to more fully explain the present invention to those skilled in the art.
Examples 1 to 3: electrode for manufacturing secondary battery
Electrode sheets were prepared in which positive electrode active materials were laminated on both sides of a coated portion of an aluminum foil current collector having a thickness of 15 μm, and insulating layers (15 μm) were laminated on both sides of a non-coated portion, respectively. The insulating layer was laminated with a composition in which boehmite and SBS were mixed in a weight ratio of 6:4.
Using a laser device having a picosecond pulse width, electrode tabs were formed by performing a dicing process on a non-coated portion of an insulating layer on which an electrode sheet was laminated under the conditions of table 1 below.
A photograph of the cut portion of the electrode tab is shown in table 1 below.
TABLE 1
In the graph of table 1, when photographed with an optical microscope, the black portion is a background, and the boundary line of the black portion is a cut portion of the electrode tab laminated with the insulating layer and the current collector. Since the figure is an image corresponding to a plan view, the upper insulating layer of the electrode tab is shown, and since the current collector located under the insulating layer is not exposed or protruded through the cut portion, it is not visible in the image. As shown in table 1, it was confirmed that the electrode manufactured by the picosecond laser of the present invention had a very excellent cut profile of the electrode tab laminated with the insulating layer and the current collector, and the problem of re-fusion of the insulating layer and the problem of exposure of the current collector due to melting of the insulating layer did not occur at all.
Comparative examples 1 to 4: electrode for manufacturing secondary battery
The electrode tabs were manufactured by performing the dicing process in the same manner as the above-described embodiment except that the dicing of the electrode tabs was performed using a laser having a nanosecond pulse width under the conditions of table 2 below.
The cut portions of the electrode tabs were photographed, and the results are shown in table 2 below.
TABLE 2
The graph in table 2 above is a photograph taken by an optical microscope, which is obtained by taking a photograph in a state where the cut portion is not completely cut or re-fused and the removed portion is not removed after cutting by a nanosecond laser. It has been confirmed that since the image corresponds to a plan view, the cut portions of the upper insulating layer and the electrode tab laminated with the insulating layer and the current collector are mainly shown, and in the case of comparative examples 1 and 2, a portion of the current collector is exposed (a shiny portion of the central portion) due to melting of the insulating layer.
As shown in table 2, in the case of the positive electrode tab cut with the nanosecond laser, various types of defects were exhibited.
In the case of comparative example 1, it was confirmed that re-fusion of the insulating layer occurred on the entire surface after dicing, and a portion of the current collector was exposed due to the fusion of the insulating layer.
In the case of comparative example 2, it was confirmed that after cutting, remelting of the insulating layer was locally generated, and the intermediate white portion was melted during cutting, and then, remelted and hardened, thereby generating an uncut portion. Further, it was confirmed that a part of the current collector was exposed (shiny part) by melting of the insulating layer.
In the case of comparative example 3, it was confirmed that after the insulator was melted by performing the notch, the insulator was fused again and the current collector was not cut.
In the case of comparative example 4, it was confirmed that cutting was performed normally, but the outer shape of the insulating layer was unevenly formed.
Comparative example 5-comparative example 7: electrode for manufacturing secondary battery
Electrode sheets were prepared in which positive electrode active materials were laminated on both sides of a coated portion of an aluminum foil current collector having a thickness of 15 μm, respectively, and insulating layers (15 μm) were laminated on both sides of a non-coated portion. The insulating layer was laminated with a composition in which boehmite and SBS were mixed in a weight ratio of 5:5.
Using a laser device having a nanosecond pulse width, electrode tabs were formed by performing a dicing process on a non-coated portion of an insulating layer on which an electrode sheet was laminated under the conditions shown in table 3 below.
The cut portions of the electrode tabs were photographed, and the results are shown in table 3 below.
TABLE 3
In table 3 above, the upper part (circular part and straight part) of the planar photograph shown as black is a background at the time of photographing with an optical microscope, the lower part is an upper insulating layer part of the electrode tab laminated with the insulating layer and the current collector, and the boundary line of the black part is a cut part of the electrode tab.
Further, in the photograph of the cross section, the sandwich shape of the central portion is the cut surface of the electrode tab laminated with the insulating layer and the current collector, and the remaining portion is the background portion at the time of photographing with an optical microscope.
As shown in table 2, in the case of the positive electrode tab cut with the nanosecond laser, various types of defects were exhibited.
In the case of comparative example 5, it can be seen that the cut end portions were rugged, the current collector protruded to the outside (bright portion adjacent to the background), the thickness of the cut surface in the sectional photograph was about 200 μm, and became very thick compared to the thickness before cutting (45 μm). The reason for the increase in thickness is that when nanosecond laser light is irradiated, the insulating layer absorbs heat and melts, thereby separating from the current collector and curling to the outside (see fig. 7). The current collector exposed in this way may deteriorate stability of the quality of the battery such as a short circuit and a low voltage.
It can be seen that even in the cases of comparative examples 6 and 7, they exhibited shapes similar to those of fig. 5, and the sectional thickness in the sectional photograph was also about 200 μm, which became very thick compared to the thickness before cutting (45 μm).
Example 4 and comparative example 8: electrode for manufacturing secondary battery
Electrode sheets were prepared in which positive electrode active materials were laminated on both sides of a coated portion of an aluminum foil current collector having a thickness of 15 μm, respectively, and insulating layers (15 μm) were laminated on both sides of a non-coated portion. The insulating layer was laminated with a composition in which boehmite and PVDF were mixed in a weight ratio of 88:12.
Using a laser device having a picosecond pulse width (example 4) or a laser device having a picosecond pulse width (comparative example 8), a positive electrode tab was formed by performing a dicing process on a non-coated portion of an insulating layer on which an electrode sheet was laminated under the conditions shown in table 4 below.
The cut portion of the positive electrode tab was photographed, and the results are shown in table 4 below.
TABLE 4
In table 4, the upper part (circular part and straight part) of the planar photograph shown as black is a background at the time of photographing with an optical microscope, the lower part is an upper insulating layer part of the electrode tab laminated with the insulating layer and the current collector, and the boundary line of the black part is a cut part of the electrode tab.
Further, in the photograph of the cross section, the sandwich shape of the central portion is the cut surface of the electrode tab laminated with the insulating layer and the current collector, and the remaining portion is the background portion at the time of photographing with an optical microscope.
As shown in table 4, it was confirmed that the electrode tab laminated with the insulating layer and the current collector notched using the picosecond laser in example 4 had an excellent cut profile, and no problem caused by re-fusion of the insulating layer occurred. Further, it was confirmed that the exposure of the current collector due to the melting of the insulating layer was minimized to 0 (circular portion) and 15.83 μm (straight portion).
Further, it was confirmed that the thickness of the cut surface in the sectional photograph was 69.25 μm, and thus the increase in thickness was minimized as compared with the thickness before cutting (45 μm).
Further, according to the experimental result of example 4, it was confirmed that if picosecond laser is used, the cutting speed can be increased to 1000mm/s or more because thermal damage of the electrode tab is small. That is, in the present invention, the cutting speed may be performed at 500mm/s to 1500mm/s. On the other hand, in the case of using nanosecond laser as in comparative example 8, when the cutting speed was increased to more than 400mm/s, the thermal damage of the electrode tab was significantly increased, and the quality was greatly deteriorated.
On the other hand, it was confirmed that the electrode tab laminated with the insulating layer and the current collector notched using the nanosecond laser in comparative example 8 had an uneven cut profile, and the current collector exposed by melting of the insulating layer was also greatly formed into 49.68 μm (circular portion) and 23.02 μm (straight portion).
Further, it was confirmed that the thickness of the cut surface in the sectional photograph was 82.71 μm, and the increase in thickness was significantly increased as compared with the thickness before cutting (45 μm). The reason for the increase in thickness is that when nanosecond laser light is irradiated, the insulating layer absorbs heat and melts, thereby separating from the current collector and curling to the outside (see fig. 7). This may deteriorate stability of the quality of the battery such as short circuit and low voltage.
Example 5: electrode for manufacturing secondary battery
Electrode sheets were prepared in which positive electrode active materials were laminated on both sides of a coated portion of an aluminum foil current collector having a thickness of 15 μm, respectively, and insulating layers (15 μm) were laminated on both sides of a non-coated portion. The insulating layer was laminated with a composition in which boehmite and SBS were mixed in a weight ratio of 6:4.
Using a laser device having a picosecond pulse width, electrode tabs were formed by performing a dicing process on a non-coated portion of an insulating layer on which an electrode sheet was laminated under the conditions shown in table 5 below.
The cut portions of the electrode tabs were photographed, and the results are shown in table 5 below.
TABLE 5
In table 5, the upper part (circular part and straight part) of the planar photograph shown as black is a background at the time of photographing with an optical microscope, the lower part is an upper insulating layer part of the electrode tab laminated with the insulating layer and the current collector, and the boundary line of the black part is a cut part of the electrode tab.
Further, in the photograph of the cross section, the sandwich shape of the central portion is the cut surface of the electrode tab laminated with the insulating layer and the current collector, and the remaining portion is the background portion at the time of photographing with an optical microscope.
As shown in table 5 above, it was confirmed that the electrode tab laminated with the insulating layer and the current collector notched using the picosecond laser in example 5 had an excellent cut profile, and no problem caused by re-fusion of the insulating layer occurred. Further, it was confirmed that the exposure of the current collector due to the melting of the insulating layer was minimized to 0 (circular portion) and 0 (straight portion).
Further, it was confirmed that the thickness of the cut surface in the sectional photograph was 71.00 μm, and the increase in thickness was minimized as compared with the thickness before cutting (45 μm)).
Although the invention has been described with reference to the preferred embodiments described above, various modifications and changes are possible without departing from the spirit and scope of the invention. It is therefore intended that the appended claims cover such modifications and variations as fall within the scope of this invention.
[ description of the reference numerals ]
10: electrode sheet 11: the insulating layer is provided with a plurality of insulating layers,
12: non-coating portion
110: positive electrode current collector 112: positive electrode tab
115: insulating layer 120: negative electrode current collector
122: negative electrode current collector 130: diaphragm
200: electrode sheet supply device 210: support roller
300: laser beam irradiation apparatus 400: clamp
410: electrode sheet supporting portion 420: and a motor.
Claims (15)
1. A method of manufacturing an electrode of a secondary battery, comprising,
(a) Preparing an electrode sheet including a current collector divided into a coated portion and a non-coated portion and having an insulating layer laminated on the non-coated portion; and
(b) The electrode tab is formed by cutting the non-coated portion on which the insulating layer is laminated,
wherein a composition having 100ps to 10 -6 The laser of pulse width ps performs the kerf.
2. The method of manufacturing an electrode of a secondary battery according to claim 1, wherein the laser has an average power energy of 10W to 200W based on an average traveling speed of 100mm/s to 2000mm/s.
3. The method of manufacturing an electrode of a secondary battery according to claim 1, wherein the average travel speed is 100mm/s to 2000mm/s during the slitting.
4. The method of manufacturing an electrode of a secondary battery according to claim 1, wherein the insulating layer comprises a polymer resin.
5. The method for manufacturing an electrode of a secondary battery according to claim 4, wherein the polymer resin is at least one selected from the group consisting of styrene-butadiene rubber, acrylate styrene-butadiene rubber, acrylonitrile-butadiene-styrene rubber, acrylic rubber, butyl rubber, fluororubber, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene copolymer, polyethylene oxide, polyvinylpyrrolidone, polypropylene oxide, polyphosphazene, polyacrylonitrile, polystyrene, ethylene-propylene-diene terpolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, hydroxypropyl methylcellulose, hydroxypropyl cellulose, and diacetyl cellulose.
6. The method of manufacturing an electrode of a secondary battery according to claim 1, wherein an active material is laminated on the coated portion of the electrode sheet.
7. The method of manufacturing an electrode for a secondary battery according to claim 1, wherein the electrode is a positive electrode or a negative electrode.
8. An electrode for a secondary battery, comprising: a laser-cut electrode tab cut in a state that an insulating layer and a current collector are laminated,
wherein the thickness of the cut section of the electrode tab is 1 to 1.7 times the thickness before cutting.
9. The electrode for a secondary battery according to claim 8, wherein the laser is a laser having a power of 100ps to 10 -6 ps.
10. The electrode for a secondary battery according to claim 8, wherein the cut profile of the electrode tab does not include dross (dross) in the form of a thread-end generated when cut with a die.
11. An electrode for a secondary battery, comprising: a laser-cut electrode tab cut in a state that an insulating layer and a current collector are laminated,
wherein in a cut section of the electrode tab, a length of the current collector protruding from the front end of the insulating layer is less than 20 μm.
12. The electrode for a secondary battery according to claim 11, wherein the laser is a laser having a power of 100ps to 10 -6 ps.
13. The electrode for a secondary battery according to claim 11, wherein the cut profile of the electrode tab does not include dross (dross) in the form of a thread-end generated when cut with a die.
14. An electrode manufacturing system, comprising:
an electrode sheet supply device for supplying an electrode sheet, the electrode sheet supply device including a current collector divided into a coated portion and a non-coated portion and having an insulating layer laminated on the non-coated portion;
a laser beam irradiation device which irradiates a laser beam having a wavelength of 100ps to 10ps -6 A laser beam of a pulse width ps to form an electrode tab by notching the non-coated portion on which the insulating layer is laminated; and
a jig for supporting a portion of the electrode sheet irradiated with the laser beam on a lower surface.
15. The electrode manufacturing system of claim 14, wherein the electrode sheet supply device is a Roll-to-Roll (Roll-to-Roll) device.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2021-0142521 | 2021-10-25 | ||
| KR10-2022-0136351 | 2022-10-21 | ||
| KR1020220136351A KR20230059153A (en) | 2021-10-25 | 2022-10-21 | Method for manufacturing an electrode for a secondary battery, Electrode for a secondary battery, and Electrode manufacturing system used in the method |
| PCT/KR2022/016216 WO2023075319A1 (en) | 2021-10-25 | 2022-10-24 | Method for manufacturing electrode for secondary battery, electrode for secondary battery, and electrode manufacturing system used for method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117413430A true CN117413430A (en) | 2024-01-16 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202280039795.XA Pending CN117413430A (en) | 2021-10-25 | 2022-10-24 | Method for manufacturing electrode of secondary battery, and electrode manufacturing system for use in the method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117413430A (en) |
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2022
- 2022-10-24 CN CN202280039795.XA patent/CN117413430A/en active Pending
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