Method of forming electrode for electrochemical cell and electrode for electrochemical cell
By setting auxiliary grooves on the electrode sheet to disperse stress, the problem of breakage at the electrode tab was solved by using laser beam cutting technology, which improved the manufacturing reliability and repeatability of electrochemical cells.
Patent Information
- Application Number
- CN202480015202.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-02-27
- Filing Date
- 2024-02-20
- Publication Date
- 2025-11-25
AI Technical Summary
During the fabrication of electrochemical batteries, the tabs of the electrode sheets are prone to cracking, tearing, or breakage due to stress concentration, which affects the manufacturing reliability and repeatability of the battery.
By setting auxiliary grooves transversely to the tab grooves on the electrode sheet, stress concentration is dispersed, reducing the risk of material breakage and tearing during transportation. Laser beam cutting technology is used to cut the tabs and auxiliary grooves on the electrode sheet.
It effectively reduces stress concentration at the starting point of the tab groove, improves the integrity of the electrode sheet and the reliability of battery manufacturing, and reduces the possibility of breakage and tearing at the tab groove.
Smart Images
Figure CN121014113A_ABST
Abstract
Description
[0001] The present invention relates to a method for forming an electrode for an electrochemical cell and an electrode for an electrochemical cell.
[0002] In the method of the present invention for preparing an electrochemical cell (e.g., a secondary electrochemical cell), the electrochemical cell includes electrodes separated from each other by a dielectric membrane.
[0003] An electrochemical cell can be manufactured by winding two electrode sheets together and inserting a dielectric membrane foil between them. These two electrode sheets serve as the anode and cathode of the electrochemical cell.
[0004] Typically, each electrode sheet is obtained by depositing an active material layer for the electrode on one or both surfaces of a current-collecting metal sheet. By selecting a suitable combination of the active material for the electrode and the metal sheet material, positive and negative electrode sheets can be obtained.
[0005] The metal sheet is not fully coated with the active material for the electrode, but the active material for the electrode is not applied to both free edges of the metal sheet or only to one free edge.
[0006] The electrode sheets are wound in such a way that, corresponding to one end of the electrochemical cell, the first electrode sheet protrudes beyond the separator foil (to define the electrodes of the electrochemical cell), and is wound in such a way that the separator foil protrudes beyond the second electrode sheet (to avoid a short circuit between the two electrode sheets). Similarly, corresponding to the second end of the electrochemical cell, the second electrode sheet protrudes beyond the separator foil, and the separator foil protrudes beyond the first electrode sheet.
[0007] Each portion of the electrode sheet protruding relative to the separator foil is uncoated with active material and serves to define the electrodes of the electrochemical cell. Specifically, the portion of each electrode sheet protruding relative to the separator foil must be folded toward the central axis of the electrochemical cell to define a (generally regular) electrode surface of the electrochemical cell, to which an electrode plate may be attached or to which the electrode surface may be attached to a cell electrode.
[0008] In order to ensure that the protruding portion of the electrode sheet can be folded correctly, multiple tabs are formed on this portion of the electrode sheet (which substantially coincides with the free edge of the metal sheet to which no active material for the electrode is applied) before the two electrode sheets are wound together with the diaphragm foil.
[0009] Based on the applicant's experience, in the method of preparing electrochemical cells, after the tabs are formed, the electrode sheets are conveyed along the conveying rollers and the return rollers to the winding station, where the electrode sheets are wound between them.
[0010] Based on the applicant's experience, during this transport operation, the electrode sheet is subjected to tension, which generates stress within the electrode sheet.
[0011] The applicant has noted that this stress can cause cracks, tears, or breakage at the tabs of the electrode sheet.
[0012] The applicant has indeed demonstrated that discontinuities occur in the sheet material where stress concentration occurs at the starting point of the groove defining the tab on the electrode sheet. Based on the applicant's experience, at these points, fracture of the electrode sheet material can trigger the formation of cracks or tears.
[0013] In other words, the applicant has observed that at one or more points where the groove begins, the tension on the electrode sheet can cause the groove to elongate, which is caused by tearing of the electrode sheet material exactly at the point where the original groove began.
[0014] The applicant argues that in order to obtain a reliable and reproducible method for manufacturing electrochemical cells, it is necessary to be able to transport electrode plates with tabs already acquired while maintaining the integrity of the tabs themselves and the electrode plates.
[0015] The applicant has recognized that it is advantageous to distribute the stress concentrated at the starting point of the groove defining the tab over a wider surface, thereby avoiding or reducing the possibility of breakage, tearing or cracking in the electrode sheet material during transport.
[0016] The applicant has discovered that by arranging the grooves transversely to the tab grooves (i.e., transversely to the grooves defining the tabs) such that each transverse groove passes through the corresponding tab groove but does not reach another tab groove, stress concentration at the electrode point at the beginning of the tab groove can be significantly reduced.
[0017] Therefore, in its first aspect, the present invention relates to a method for forming an electrode for an electrochemical cell.
[0018] Preferably, the electrode sheet is provided with thickness, length and height, wherein the length is measured along the longitudinal direction, the height is measured along the transverse direction, and the thickness is measured along the direction perpendicular to both the longitudinal and transverse directions.
[0019] Preferably, the electrode sheet includes a first portion with longitudinal free edges that is not coated with electrode active material.
[0020] Preferably, the electrode sheet includes a second portion coated with an electrode active material.
[0021] Preferably, multiple tab grooves are cut on the electrode sheet.
[0022] Preferably, the tab groove is cut in the first portion of the electrode sheet that extends laterally from the free edge.
[0023] Preferably, each tab groove extends from the outer lateral end to the inner lateral end.
[0024] Preferably, a plurality of auxiliary grooves are cut on the electrode sheet in the first portion of the electrode sheet.
[0025] Preferably, each auxiliary groove extends longitudinally and contacts a single electrode groove between the lateral outer end and the lateral inner end of the electrode groove.
[0026] In a second aspect, the present invention relates to an electrode for an electrochemical cell.
[0027] Preferably, an electrode sheet is provided having thickness, length, and height, wherein the length is measured along the longitudinal direction, the height is measured along the transverse direction, and the thickness is measured along a direction perpendicular to both the longitudinal and transverse directions.
[0028] Preferably, the electrode sheet includes a first portion with longitudinal free edges that is not coated with electrode active material.
[0029] Preferably, the electrode sheet includes a second portion coated with an electrode active material.
[0030] Preferably, the electrode sheet is provided with multiple tab grooves.
[0031] Preferably, the tab groove is located in the first portion of the electrode sheet extending laterally from the free edge.
[0032] Preferably, each tab groove extends from the outer lateral end to the inner lateral end.
[0033] Preferably, a plurality of auxiliary grooves are provided on the electrode sheet in the first portion of the electrode sheet.
[0034] Preferably, each auxiliary groove extends longitudinally and contacts a single electrode groove between the lateral outer end and the lateral inner end of the electrode groove.
[0035] In this specification and the following claims, the term "longitudinal" refers to a direction substantially parallel to the main extension direction of the electrode sheet. The electrode sheet can be considered as a very thin plate extending longitudinally between its two opposite and furthest free edges.
[0036] In this specification and the following claims, the term "lateral" refers to a direction contained within a plane containing the longitudinal direction and substantially perpendicular to the longitudinal direction. The electrode sheet can be considered as a very thin plate, with the lateral direction extending between two opposite and nearest free edges of such a plate.
[0037] In this specification and the following claims, the terms "lateral outside" and "lateral inside" refer to locations that are closer to and further away from the longitudinal free edge, respectively, in the lateral direction.
[0038] The present invention may have at least one of the following preferred features. Unless otherwise expressly stated, these features may exist individually or in combination with each other in the method of forming an electrode for an electrochemical cell and in the electrode for an electrochemical cell of the present invention.
[0039] Preferably, the thickness of the electrode sheet is at least two orders of magnitude smaller than the lateral dimension of the electrode sheet.
[0040] Preferably, the lateral dimension of the electrode sheet is at least one order of magnitude smaller than the longitudinal dimension of the electrode sheet.
[0041] Preferably, the electrode sheet includes a second portion of the electrode sheet that is transversely continuous with the first portion of the electrode sheet.
[0042] Preferably, multiple tab grooves are completely cut into the first portion of the electrode sheet.
[0043] Preferably, cutting multiple tab grooves includes cutting multiple tab grooves that are parallel to each other and spaced apart by a corresponding groove distance.
[0044] Preferably, the groove distance is measured in the longitudinal direction.
[0045] Preferably, the groove distances between the multiple tab grooves are equal.
[0046] Preferably, cutting the plurality of auxiliary grooves includes cutting each auxiliary groove, each auxiliary groove having a first portion extending from the corresponding tab groove toward a first adjacent tab groove.
[0047] Preferably, the first portion of each auxiliary groove does not reach the first adjacent tab groove.
[0048] Preferably, cutting multiple auxiliary grooves includes cutting each auxiliary groove, each auxiliary groove further having a second portion extending from the corresponding tab groove toward a second adjacent tab groove.
[0049] Preferably, the second portion of each auxiliary groove extends longitudinally on the opposite side to the first portion of the corresponding auxiliary groove.
[0050] Preferably, the second portion of each auxiliary groove does not reach the first adjacent tab groove.
[0051] Preferably, the first part of each auxiliary groove is directly connected to the second part of the corresponding auxiliary groove.
[0052] Preferably, each first portion of the auxiliary groove has a longitudinal length measured from the corresponding tab groove toward the first adjacent tab groove, and the longitudinal length is 10% to 90% of the corresponding groove distance.
[0053] The applicant has discovered that, in this manner, the auxiliary groove can generate a preferred longitudinal fold line for each tab, which tends to define a hinge line, along which the tab tends to fold more easily when subjected to folding pressure outside the plane defined by the electrode sheet.
[0054] Preferably, each first portion of the auxiliary groove has a longitudinal length measured from the corresponding tab groove toward the first adjacent tab groove, the longitudinal length being 10% to 80% of the corresponding groove distance.
[0055] Preferably, each first portion of the auxiliary groove has a longitudinal length measured from the corresponding tab groove toward the first adjacent tab groove, the longitudinal length being 10% to 70% of the corresponding groove distance.
[0056] Preferably, each first portion of the auxiliary groove has a longitudinal length measured from the corresponding tab groove toward the first adjacent tab groove, the longitudinal length being 10% to 60% of the corresponding groove distance.
[0057] Preferably, each first portion of the auxiliary groove has a longitudinal length measured from the corresponding tab groove toward the first adjacent tab groove, the longitudinal length being 10% to 49% of the corresponding groove distance.
[0058] In this case, preferably, each second portion of the auxiliary groove has a longitudinal length measured from the corresponding tab groove toward the second adjacent tab groove, the longitudinal length being 10% to 49% of the corresponding groove distance.
[0059] Preferably, the sum of the longitudinal length of each first portion of the auxiliary groove and the longitudinal length of the corresponding second portion of the auxiliary groove is 10% to 90% of the groove distance between two adjacent tab grooves.
[0060] Preferably, the sum of the longitudinal length of each first portion of the auxiliary groove and the longitudinal length of the corresponding second portion of the auxiliary groove is 10% to 80% of the groove distance between two adjacent tab grooves.
[0061] Preferably, the sum of the longitudinal length of each first portion of the auxiliary groove and the longitudinal length of the corresponding second portion of the auxiliary groove is 10% to 70% of the groove distance between two adjacent tab grooves.
[0062] Preferably, the sum of the longitudinal length of each first portion of the auxiliary groove and the longitudinal length of the corresponding second portion of the auxiliary groove is 10% to 60% of the groove distance between two adjacent tab grooves.
[0063] Preferably, the sum of the longitudinal length of each first portion of the auxiliary groove and the longitudinal length of the corresponding second portion of the auxiliary groove is 10% to 50% of the groove distance between two adjacent tab grooves.
[0064] Preferably, the sum of the longitudinal length of each first portion of the auxiliary groove and the longitudinal length of the corresponding second portion of the auxiliary groove is 10% to 40% of the groove distance between two adjacent tab grooves.
[0065] Preferably, the lateral inner ends of the tab grooves are aligned with each other along a straight line.
[0066] Preferably, the straight line extends longitudinally.
[0067] Preferably, cutting multiple auxiliary grooves includes cutting auxiliary grooves that pass through the lateral inner end of the corresponding tab groove.
[0068] Preferably, each auxiliary groove passes through the lateral inner end of the corresponding tab groove.
[0069] Optionally, the auxiliary groove is preferably inserted between the lateral outer end and the lateral inner end of the electrode tab.
[0070] In this case, preferably, the auxiliary groove does not extend through the lateral inner end of the electrode tab.
[0071] Preferably, cutting multiple tab grooves includes guiding a laser beam onto the electrode sheet.
[0072] Preferably, guiding the laser beam onto the electrode sheet includes conveying the electrode sheet along the conveying direction and moving the laser beam relative to the electrode sheet.
[0073] Preferably, the electrode sheet is conveyed longitudinally.
[0074] Preferably, guiding the laser beam onto the electrode sheet includes conveying the electrode sheet along the conveying direction and moving the laser beam relative to the electrode sheet.
[0075] Preferably, cutting multiple auxiliary grooves includes guiding a laser beam onto the electrode sheet.
[0076] Preferably, multiple auxiliary grooves are cut during the conveying of the electrode sheet along the conveying direction.
[0077] Preferably, the same laser beam is used to cut multiple tab grooves and multiple auxiliary grooves.
[0078] Preferably, the reduction of the electrode sheet thickness is carried out substantially simultaneously with the cutting of multiple electrode tabs.
[0079] Preferably, cutting multiple auxiliary grooves involves guiding a laser beam onto an electrode sheet that defines a processing trajectory.
[0080] Preferably, the processing trajectory starts from the initial point, bends in a U-shape along the first straight segment, and returns to the initial point along the second straight segment.
[0081] Preferably, cutting multiple tab grooves includes guiding the laser beam onto the electrode sheet along the processing trajectory.
[0082] Preferably, in order to cut the plurality of tab grooves, the processing trajectory, during its return toward the initial point, undergoes further bending, following a meandering path spanning between the first and second straight segments until the endpoint.
[0083] Preferably, the first straight segment of the processing path coincides with the longitudinal alignment direction of the auxiliary groove.
[0084] Preferably, the second straight segment of the processing path coincides with the free edge of the electrode sheet.
[0085] Preferably, the straight section of the meandering path coincides with the groove of the electrode tab.
[0086] Further features and advantages of this specification will become clearer from the following detailed description of its preferred embodiments, with reference to the accompanying drawings and by way of indicative and non-limiting examples, wherein:
[0087] - Figure 1 A front view of a portion of an electrode for an electrochemical cell according to the present invention;
[0088] - Figures 2 to 4 for Figure 1 A front view of a possible alternative implementation scheme for the middle electrode;
[0089] - Figure 5 A schematic diagram of an apparatus capable of implementing the method for forming electrodes for an electrochemical cell according to the present invention; and
[0090] - Figure 6 This is a schematic diagram illustrating the implementation steps of a method for forming an electrode for an electrochemical cell according to the present invention.
[0091] The electrode for electrochemical cells according to the present invention is in Figure 1 It is indicated by reference numeral 10 in the attached figure.
[0092] Electrode 10 can be used to manufacture the cathode or anode of an electrochemical cell.
[0093] Electrode 10 includes an electrode sheet 11 with a thickness of 3 to 500 micrometers. The length L of the electrode sheet 11 is 1 to 50 meters, preferably 2 to 20 meters, for example, about 6 meters. The height H of the electrode sheet 11 typically depends on the height of the electrochemical cell to be manufactured. The height H of the electrode sheet 11 can, for example, be approximately equal to the height of the electrochemical cell to be manufactured, or can be approximately twice the height of the electrochemical electrode to be manufactured. For example, the height H of the electrode sheet can be 3 centimeters and 30 centimeters, preferably 4 centimeters and 20 centimeters, for example, about 10 centimeters.
[0094] The electrode sheet 11 includes opposing longitudinal free edges 12a, 12b that extend substantially over the entire length of the electrode sheet 11 and are spaced apart from each other from the height H of the electrode sheet 11.
[0095] The electrode sheet 11 includes a sheet current collector 13, which can be a metal sheet or an alloy sheet. The metal sheet can include copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold or silver. The alloy sheet can include stainless steel or an alloy including at least one of the following elements: copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold or silver.
[0096] The electrode sheet 11 also includes an active material for the electrode 14 applied to one or both surfaces of the current collector 13.
[0097] The active material used for electrode 14 can be an anode material or a cathode material. In the case of an anode material, it can include graphite or other carbon-containing materials or silicon-based materials. In the case of a cathode material, it can include lithium oxide, nickel, manganese, cobalt, aluminum or lithium and iron phosphate-based materials.
[0098] like Figure 1 As illustrated, the active material used for electrode 14 only partially covers current collector 13.
[0099] In a preferred embodiment of the invention, the electrode sheet 11 includes at least a first portion 15 without active material for the electrode 14 and a second portion 16 with active material for the electrode 14. The first portion 15 and the second portion 16 with free edges extend longitudinally substantially over the entire length L of the electrode sheet 11.
[0100] exist Figure 1 In the illustrated embodiment, only the first portion 15 of the electrode sheet 11 is provided, which does not have active material for the electrode 14. In other embodiments not shown, two first portions 15 may be provided that are laterally opposite each other and separate from the second portion 16.
[0101] The first portion 15 extends laterally from free edge 12a toward another free edge 12b, but does not reach the other free edge 12b. The lateral extension of the first portion 15 of the electrode sheet 11 is less than the lateral extension of the second portion 16.
[0102] The electrode sheet 11 includes a plurality of tabs 17 disposed in the first electrode portion 15.
[0103] The tab 17 is formed by the tab groove 19. The tab groove 19 is a through cut in the electrode plate 11.
[0104] The tab groove 19 extends laterally from the free edge 12a toward the second part 16, but does not reach the second part 16 of the electrode plate 11.
[0105] The tab grooves 19 follow each other longitudinally along the electrode plates 11.
[0106] The distance between two longitudinally continuous tab grooves 19 defines the groove distance D.
[0107] All grooves are equidistant from each other by a distance D.
[0108] Each tab 17 is defined laterally by an upper edge 18 and longitudinally by two adjacent tab grooves 19. The upper edge 18 is substantially aligned with the free edge 12a of the electrode sheet 11, and the tab grooves 19 extend laterally from the upper edge 18.
[0109] The upper edge 18 of each tab 17 defines the lateral outer end 17a of the tab 17, and the point of the tab groove 19 further laterally away from the upper edge 18 defines the lateral inner end 17b of the tab 17. The point of the tab groove 19 further laterally away from the upper edge 18 further defines the lateral inner end 19a of the tab groove 9. The upper edge 18 of each tab 17 defines the lateral outer end 19b of the tab groove 17 at each tab groove 17.
[0110] like Figure 1 As shown, the lateral inner ends 19a of the tab grooves 19 are aligned with each other along a straight line R. This straight line R is preferably parallel to the free edge 12a of the electrode sheet 11. The line R is completely contained within the first portion 15 of the electrode sheet 11, that is, the portion of the electrode sheet 11 that does not have the active material for the electrode 14.
[0111] In a preferred embodiment of the invention, the tab groove 19 simultaneously defines a second tab groove 19 for the first tab 17 and a first tab groove 19 immediately adjacent to the second tab 19 of the first tab 17. The distance between each tab 17 and the immediately preceding tab 17 is much smaller than the longitudinal width of the tab 17. In other words, the longitudinal thickness of the tab groove 19 is much smaller than the longitudinal distance between two adjacent tab grooves 19. The longitudinal thicknesses of the tab grooves 19 are equal to each other.
[0112] The electrode 10 also includes a plurality of auxiliary grooves 20 obtained on the electrode sheet 11 in the first portion 15 of the electrode sheet 11.
[0113] Each auxiliary groove 20 extends longitudinally and contacts a single tab groove 19 between the lateral outer end 19b and the lateral inner end 19a of the tab groove 19.
[0114] Auxiliary grooves 20 are present on all tab grooves 19.
[0115] The thickness of the auxiliary groove 20 in the lateral direction is much smaller than the distance in the longitudinal direction between two adjacent tab grooves 19.
[0116] The thickness of the auxiliary groove 20 in the transverse direction is basically equal to the thickness of the tab groove 19 in the longitudinal direction.
[0117] The auxiliary grooves 20 have equal thickness in the lateral direction.
[0118] exist Figure 1 In the implementation scheme, the auxiliary groove 20 is provided across the corresponding tab groove 19.
[0119] Each auxiliary groove 20 includes a first portion 21 and a second portion 22. The first portion 21 extends in a first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove 19. The second portion 22 extends in a second longitudinal direction opposite to the first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove 19.
[0120] The first portion 21 and the second portion 22 of each auxiliary groove 20 are aligned with each other and are continuous in the longitudinal direction.
[0121] All auxiliary grooves 20 are aligned with each other along the longitudinal direction parallel to the free edge 12a of the electrode sheet 11.
[0122] All auxiliary grooves 20 are located between the inner lateral end 19a and the outer lateral end 19b of the tab groove 19. All auxiliary grooves 20 are closer to the inner lateral end 19a of the tab groove 19 and further away from the outer lateral end 19b of the tab groove 19.
[0123] All auxiliary grooves 20 are laterally positioned between the straight line R (the lateral inner end 19a of the tab groove 19 is aligned with the straight line R) and the free edge 12a of the electrode sheet 11.
[0124] Each first portion 21 of the auxiliary groove 20 has a longitudinal length L1, which is measured in the first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove. The longitudinal length L1 is 10% to 45% of the corresponding groove distance D, preferably 10% to 30% of the corresponding groove distance D, for example, 20% of the corresponding groove distance D.
[0125] All the first portions 21 of the auxiliary groove 20 have equal longitudinal lengths L1.
[0126] Each second portion 22 of the auxiliary groove 20 has a longitudinal length L2, which is measured in the second longitudinal direction (opposite to the first longitudinal direction) from the corresponding tab groove 19 toward the adjacent tab groove. The longitudinal length L2 is 10% to 45% of the corresponding groove distance D, preferably 10% to 30% of the corresponding groove distance D, for example, 20% of the corresponding groove distance D.
[0127] All the second portions 21 of the auxiliary groove 20 have equal longitudinal lengths L2.
[0128] The sum of the longitudinal lengths L1 and L2 of the first portion 21 and the second portion 22 of each auxiliary groove 20 is 20% to 60% of the groove distance D, preferably 20% to 50% of the groove distance D, for example, 40% of the groove distance D.
[0129] The sum of the longitudinal lengths L1 and L2 of the first portion 21 and the second portion 22 of each auxiliary groove 20 defines the longitudinal length L3 of the auxiliary groove 20.
[0130] The longitudinal length L1 of the first part 21 of the auxiliary groove 20 is equal to the longitudinal length L2 of the second part 22 of the auxiliary groove 20.
[0131] exist Figure 2 In one embodiment, the auxiliary groove 20 extends only along the first longitudinal direction between the tab groove 19 and the subsequent adjacent tab groove 19.
[0132] Each auxiliary groove 20 includes a single first portion 21. The first portion 21 extends in a first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove 19.
[0133] All auxiliary grooves 20 are aligned with each other along the longitudinal direction parallel to the free edge 12a of the electrode sheet 11.
[0134] All auxiliary grooves 20 are located between the inner lateral end 19a and the outer lateral end 19b of the tab groove 19. All auxiliary grooves 20 are closer to the inner lateral end 19a of the tab groove 19 and further away from the outer lateral end 19b of the tab groove 19.
[0135] All auxiliary grooves 20 are laterally positioned between the straight line R (the lateral inner end 19a of the tab groove 19 is aligned with the straight line R) and the free edge 12a of the electrode sheet 11.
[0136] Each first portion 21 of the auxiliary groove 20 has a longitudinal length L1, which is measured in the first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove. The longitudinal length L1 is 10% to 80% of the corresponding groove distance D, preferably 20% to 70% of the corresponding groove distance D, for example, 40% of the corresponding groove distance D.
[0137] All the first portions 21 of the auxiliary groove 20 have equal longitudinal lengths L1.
[0138] The longitudinal length L1 of the first portion 21 of each auxiliary groove 20 defines the longitudinal length L3 of the auxiliary groove 20.
[0139] exist Figure 3 In the implementation scheme, the auxiliary notch 20 is provided across the corresponding tab groove 19.
[0140] Each auxiliary groove 20 includes a first portion 21 and a second portion 22. The first portion 21 extends in a first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove 19. The second portion 22 extends in a second longitudinal direction opposite to the first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove 19.
[0141] The first portion 21 and the second portion 22 of each auxiliary groove 20 are aligned with each other and are continuous in the longitudinal direction.
[0142] All auxiliary grooves 20 are aligned with each other along the longitudinal direction parallel to the free edge 12a of the electrode sheet 11.
[0143] All auxiliary grooves 20 are located at the inner lateral end 19a of the tab groove 19. All auxiliary grooves 20 pass through the inner lateral end 19a of the corresponding tab groove 19.
[0144] All auxiliary grooves 20 are aligned with the straight line R (the lateral inner end 19a of the tab groove 19 is aligned with the straight line R).
[0145] Each first portion 21 of the auxiliary groove 20 has a longitudinal length L1, which is measured in the first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove. The longitudinal length L1 is 10% to 45% of the corresponding groove distance D, preferably 10% to 30% of the corresponding groove distance D, for example, 20% of the corresponding groove distance D.
[0146] All the first portions 21 of the auxiliary groove 20 have equal longitudinal lengths L1.
[0147] Each second portion 22 of the auxiliary notch 20 has a longitudinal length L2, which is measured in the second longitudinal direction (opposite to the first longitudinal direction) from the corresponding tab groove 19 toward the adjacent tab groove. The longitudinal length L2 is 10% to 45% of the corresponding groove distance D, preferably 10% to 30% of the corresponding groove distance D, for example, 20% of the corresponding groove distance D.
[0148] All the second portions 21 of the auxiliary groove 20 have equal longitudinal lengths L2.
[0149] The sum of the longitudinal lengths L1 and L2 of the first portion 21 and the second portion 22 of each auxiliary groove 20 is 20% to 60% of the groove distance D, preferably 20% to 50% of the groove distance D, for example, 40% of the groove distance D.
[0150] The sum of the longitudinal lengths L1 and L2 of the first portion 21 and the second portion 22 of each auxiliary groove 20 defines the longitudinal length L3 of the auxiliary groove 20.
[0151] The longitudinal length L1 of the first part 21 of the auxiliary groove 20 is equal to the longitudinal length L2 of the second part 22 of the auxiliary groove 20.
[0152] exist Figure 4 In one embodiment, the auxiliary groove 20 extends only along the first longitudinal direction between the tab groove 19 and the subsequent adjacent tab groove 19.
[0153] Each auxiliary groove 20 includes a single first portion 21. The first portion 21 extends in a first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove 19.
[0154] All auxiliary grooves 20 are aligned with each other along the longitudinal direction parallel to the free edge 12a of the electrode sheet 11.
[0155] All auxiliary grooves 20 are located at the inner lateral end 19a of the tab groove 19. All auxiliary grooves 20 pass through the inner lateral end 19a of the corresponding tab groove 19.
[0156] All auxiliary grooves 20 are aligned with the straight line R (the lateral inner end 19a of the tab groove 19 is aligned with the straight line R).
[0157] Each first portion 21 of the auxiliary groove 20 has a longitudinal length L1, which is measured in the first longitudinal direction from the corresponding tab groove 19 toward the adjacent tab groove. The longitudinal length L1 is 10% to 80% of the corresponding groove distance D, preferably 20% to 70% of the corresponding groove distance D, for example, 40% of the corresponding groove distance D.
[0158] All the first portions 21 of the auxiliary groove 20 have equal longitudinal lengths L1.
[0159] The longitudinal length L1 of the first portion 21 of each auxiliary groove 20 defines the longitudinal length L3 of the auxiliary groove 20.
[0160] The method of manufacturing electrode 10 according to the present invention provides for applying an active material for electrode 14 to a portion or the entire current collector 13.
[0161] When the active material for electrode 14 is applied to only a portion of current collector 13, that portion is defined by the second portion 16 of electrode sheet 11.
[0162] When the active material for electrode 14 is applied to the entire current collector 13, the operation is followed by an operation of ablating the active material for electrode 14 from a portion of the current collector 13 in order to obtain the second portion 16 of electrode sheet 11.
[0163] In both cases, a first portion 15 is obtained on the electrode sheet 11, which extends laterally from the free edge 12a of the electrode sheet 11 and is not coated with the active material for the electrode 14.
[0164] These operations can be performed on one surface of the current collector 13 or on both surfaces of the current collector 13.
[0165] The electrode sheet 11 thus obtained can be wound up to form an electrode sheet roll 23 for temporary storage or direct use.
[0166] Electrode sheet 11 is unwound from electrode sheet roll 23 to feed along the conveying path P in the conveying direction T (e.g., Figure 5 (As shown).
[0167] A laser device 24 is disposed above the transport path P. The laser device 24 includes a laser oscillator 25 that emits a laser beam and a galvanometric scanner 26 configured to move the focal point of the laser beam and focus it at a desired position along the transport path P and on the electrode plate 11. The galvanometric scanner 26 is a device configured to deflect the laser beam along two mutually orthogonal directions located within the plane defined by the electrode plate 11 below the laser device 24. The galvanometric scanner 26 may include two mirrors mounted on a galvanometer, such that they rotate on mutually inclined and preferably perpendicular axes.
[0168] When the electrode sheet 11 travels along the conveying path P in the conveying direction T, the laser device 24 is activated to cut multiple tab grooves 19 and multiple auxiliary grooves 20.
[0169] The operation of cutting multiple tab grooves 19 and multiple auxiliary grooves 20 is carried out in a "dynamic" manner, that is, while the electrode sheet 11 moves along the conveying direction T.
[0170] In a preferred embodiment of the invention, the combined motion of the electrode plate 11 (moving in a linear motion) and the laser beam (moving along two mutually orthogonal directions within the plane defined by the electrode plate 11) results in a machining trajectory 27 on the electrode plate 11 with the focal point of the laser beam at that point. This machining trajectory 27 is as follows: Figure 6 As shown.
[0171] The laser beam is focused on the processing path 27 on the electrode sheet 11 and travels repeatedly a sufficient number of times in a substantially overlapping manner to cut the multiple tab grooves 19 and multiple auxiliary grooves 20 along the electrode sheet 11 to the required length.
[0172] In a preferred embodiment of the invention, the processing trajectory 27 begins at an initial point 28, bends in a U-shape along a first straight segment 29, returns towards the initial point 28 along a second straight segment 30, bends further, and then follows a meandering path 31 (composed of bends and straight segments 32) spanning the first straight segment 28 and the second straight segment 30 until it reaches an endpoint 33. The endpoint 33 of each processing trajectory 27 coincides with the initial point 28 in subsequent processing trajectories 27.
[0173] Make the first straight segment 29 of the processing path 27 coincide with the longitudinal alignment direction of the auxiliary groove 20, make the second straight segment 30 of the processing path 27 coincide with the free edge 12a of the electrode sheet 11, and make the straight segment 32 of the meandering path 31 coincide with the tab groove 19 to be cut.
[0174] The tab groove 19 and the auxiliary groove 20 can be cut by modulating the power of the laser oscillator 25 between a minimum power equal to zero and a maximum power equal to zero.
[0175] Specifically, in order to cut the tab groove 19, the power of the laser oscillator 25 is set to a first power capable of cutting through the groove in the electrode sheet 11. This first power is used when the focus of the laser beam travels along the straight section 32 of the meandering path 31 of the processing trajectory 27.
[0176] To cut the auxiliary groove 20, the power of the laser oscillator 25 is set to a first power capable of cutting through the groove in the electrode sheet 11. The first power is used when the focus of the laser beam travels along the first straight section 29 of the processing path 27 and at the auxiliary groove 20 to be cut.
[0177] As the laser beam travels along the first straight section 29 of the processing path 27 and at the intervals between the auxiliary grooves 20 to be cut (i.e., at the portion of the electrode sheet unaffected by the auxiliary grooves 20), the power of the laser oscillator 25 is set to a second power, essentially zero.
[0178] When the tab groove 19 and auxiliary groove 20 are cut on the processed portion of the electrode sheet 11, the electrode sheet continues to travel along the transport path P in the transport direction T so as to be wound up and form another electrode sheet roll 34.
Claims
1. A method for forming an electrode for an electrochemical cell, comprising: An electrode sheet (11) is provided with a thickness, a length (L) and a height (H), wherein the length (L) is measured along the longitudinal direction, the height (H) is measured along the transverse direction, and the thickness is measured along a direction perpendicular to the longitudinal and transverse directions. The electrode sheet (11) includes a first portion (15) uncoated with electrode active material and a second portion (16) coated with electrode active material, having a longitudinal free edge (12a). A plurality of tab grooves (19) are cut on the electrode sheet (11) in the first part (15) of the electrode sheet (11), wherein each tab groove (11) extends from the outer lateral end (19b) to the inner lateral end (19a); Multiple auxiliary grooves (20) are cut on the electrode sheet (11) in the first part (15) of the electrode sheet (11), wherein each auxiliary groove (20) extends longitudinally and contacts a single tab groove (19) between the lateral outer end (19b) and the lateral inner end (19a) of the tab groove (19).
2. The method according to claim 1, wherein cutting the plurality of tab grooves (19) comprises cutting a plurality of tab grooves (19) that are parallel to each other and spaced apart by a corresponding groove distance (D); cutting the plurality of auxiliary grooves (20) comprises cutting each auxiliary groove (20) having a first portion (21) extending from the corresponding tab groove (19) toward a first adjacent tab groove (19).
3. The method according to claim 2, wherein, Each first portion (21) of the auxiliary groove has a longitudinal length (L1) measured from the corresponding tab groove (19) toward the first adjacent tab groove (19), and the longitudinal length (L1) is 10% to 90% of the corresponding groove distance (D).
4. The method according to claim 2 or 3, wherein, Cutting multiple auxiliary grooves (20) includes cutting each auxiliary groove (20), each auxiliary groove (20) further having a second portion (22) extending from the corresponding tab groove (19) toward a second adjacent tab groove (19).
5. The method according to claim 4, wherein, Each second tab portion (22) has a longitudinal length (L2) measured from the corresponding tab groove (19) toward the second adjacent tab groove (19), the longitudinal length (L2) being 10% to 49% of the corresponding groove distance (D); and wherein each first portion (21) of the auxiliary groove has a longitudinal length (L1) measured from the corresponding tab groove (19) toward the first adjacent tab groove (19), the longitudinal length (L1) being 10% to 49% of the corresponding groove distance (D).
6. The method according to claim 5, wherein, The sum of the longitudinal length (L1) of each first portion (21) of the auxiliary groove and the longitudinal length (L2) of the corresponding second portion (22) of the auxiliary groove is 10% to 90% of the groove distance (D) between two adjacent tab grooves (19).
7. The method according to any one of the preceding claims, wherein, Cutting multiple auxiliary grooves (20) includes cutting auxiliary grooves (20) that do not pass through the lateral inner end (19a) of the corresponding tab groove (19).
8. The method according to any one of the preceding claims, wherein, The transverse inner ends (19a) of the tab grooves (19) are aligned with each other along a straight line (R).
9. The method according to any one of the preceding claims, wherein cutting the plurality of auxiliary grooves (20) includes guiding a laser beam onto the electrode sheet (11) defining a processing trajectory (27), the processing trajectory (27) being: Start from the initial point (28); Along the first straight segment (29); Perform a U-shaped bend; The second straight segment (30) returns along the path toward the initial point (28).
10. The method of claim 9, wherein cutting the plurality of tab grooves (19) comprises guiding the laser beam onto the electrode sheet (11), wherein the processing trajectory (27) returns toward the initial point (28): Perform further bending; Follow the winding path (31) that spans between the first straight section (29) and the second straight section (30) until the end.
11. The method according to claim 10, wherein, Make the first straight segment (29) of the processing path (27) coincide with the longitudinal alignment direction of the auxiliary groove (20), make the second straight segment (30) of the processing path (27) coincide with the free edge (12a) of the electrode sheet (11), and make the straight segment (32) of the meandering path (31) coincide with the tab groove (19).
12. The electrode (10) for use in an electrochemical cell includes: An electrode sheet (11) has a thickness, a length (L) and a height, wherein the length (L) is measured along the longitudinal direction, the height (H) is measured along the transverse direction, and the thickness is measured along a direction perpendicular to both the longitudinal and transverse directions. The electrode sheet (11) includes a first portion (15) uncoated with electrode active material and a second portion (16) coated with electrode active material, having a longitudinal free edge (12a). Multiple tab grooves (19) are located on the electrode sheet (11) in the first portion (15) of the electrode sheet (11), wherein each tab groove (11) extends from a laterally outer end (19b) to a laterally inner end (19a); Multiple auxiliary grooves (20) are located on the electrode sheet (11) in the first portion (15) of the electrode sheet (11), wherein each auxiliary groove (20) extends longitudinally and contacts a single tab groove (19) between the lateral outer end (19b) and the lateral inner end (19a) of the tab groove (19).
13. The electrode according to claim 12, wherein, The tab grooves (19) are parallel to each other and spaced apart by a corresponding groove distance (D); each auxiliary groove (20) includes a first portion (21) extending from the corresponding tab groove (19) toward the first adjacent tab groove (19).
14. The electrode according to claim 13, wherein, Each first portion (21) of the auxiliary groove has a longitudinal length (L1) measured from the corresponding tab groove (19) toward the first adjacent tab groove (19), and the longitudinal length (L1) is 10% to 90% of the corresponding groove distance (D).
15. The electrode according to claim 13 or 14, wherein, Each auxiliary groove (20) also includes a second portion (22) extending from the corresponding tab groove (19) toward the second adjacent tab groove (19).
16. The electrode according to claim 15, wherein, Each second tab portion (22) has a longitudinal length (L2) measured from the corresponding tab groove (19) toward the second adjacent tab groove (19), the longitudinal length (L2) being 10% to 49% of the corresponding groove distance (D); and wherein each first portion (21) of the auxiliary groove has a longitudinal length (L1) measured from the corresponding tab groove (19) toward the first adjacent tab groove (19), the longitudinal length (L1) being 10% to 49% of the corresponding groove distance (D).
17. The electrode according to claim 16, wherein, The sum of the longitudinal length (L1) of each first portion (21) of the auxiliary groove and the longitudinal length (L2) of the corresponding second portion (22) of the auxiliary groove is 10% to 90% of the groove distance (D) between two adjacent tab grooves (19).
18. The electrode according to claim 16 or 17, wherein, The longitudinal length (L1) of the first part (21) of each auxiliary groove (20) is equal to the longitudinal length (L2) of the second part (22).
19. The electrode according to any one of claims 12 to 18, wherein, Each auxiliary groove (20) does not pass through the lateral inner end (19a) of the corresponding tab groove (19).
20. The electrode according to any one of claims 12 to 19, wherein, The transverse inner ends (19a) of the tab grooves (19) are aligned with each other along a straight line (R).
21. The electrode of claim 13, wherein the groove distance (D) is equal to each other.