Method of forming electrode for electrochemical cell and electrode for electrochemical cell
By setting longitudinal weakening lines on the electrode sheet and using laser thinning technology, the problem of inaccurate electrode sheet folding was solved, and the stability and reliability of electrochemical cell manufacturing were achieved.
Patent Information
- Application Number
- CN202480015092.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2023-02-27
- Filing Date
- 2024-02-20
- Publication Date
- 2025-10-28
AI Technical Summary
In the prior art, it is difficult to accurately fold the electrode sheet to the required area when folding the tab, which leads to instability and unreliability in the manufacture of electrochemical cells.
Longitudinal weakening lines are set on the electrode sheet, and the electrode sheet thickness is reduced by laser to form preferential folding lines, which guide the tab rotation and folding.
This improves the reliability and consistency of electrode folding, ensuring stable manufacturing of electrochemical cells.
Smart Images
Figure CN120858461A_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 order to fold the tabs of each electrode sheet, a folding pressure must be applied to these tabs toward the central axis of the electrochemical cell. This folding pressure, even if applied only to the corresponding tab, is easily transmitted to the portion of the electrode sheet immediately adjacent to the tab. This portion of the electrode sheet is stacked on and supported by the separator foil. However, in the corresponding portion of the electrode sheet, the separator foil is not stacked on and supported by the other electrode sheet.
[0010] Therefore, based on the applicant's experience when folding the tabs, even the parts of the electrode sheet that are not affected by the tabs can fold.
[0011] Therefore, based on the applicant's experience, it is not always possible to guarantee that the electrode sheets used in the method of forming an electrochemical cell are always actually folded in the required folding area at the tab.
[0012] The applicant believes that in order to obtain a reliable and reproducible method for manufacturing electrochemical cells, it is necessary to have tabs that can be folded according to the desired or selected folding regions.
[0013] The applicant has recognized that it is advantageous to have longitudinally extending lines on the electrode sheet, which can facilitate or guide the rotation of the tabs during folding.
[0014] The applicant has discovered that by structurally weakening the electrode sheet along a longitudinal path disposed on the electrode sheet, the tabs will be easier to rotate when folding pressure is applied to the electrode sheet, and then fold around the longitudinal path, thereby predetermining the folding area of the tabs of the electrode sheet.
[0015] Therefore, in its first aspect, the present invention relates to a method for forming an electrode for an electrochemical cell.
[0016] 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.
[0017] Preferably, the electrode sheet includes a first portion with longitudinal free edges that is not coated with electrode active material.
[0018] Preferably, the electrode sheet includes a second portion coated with an electrode active material.
[0019] Preferably, a plurality of tabs are cut on the electrode sheet in the first portion of the electrode sheet extending laterally from the free edge.
[0020] Preferably, the thickness of the electrode sheet is reduced along a longitudinal trajectory contained in the first portion of the electrode sheet.
[0021] In a second aspect, the present invention relates to an electrode for an electrochemical cell.
[0022] 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.
[0023] Preferably, the electrode sheet includes a first portion with longitudinal free edges that is not coated with electrode active material.
[0024] Preferably, the electrode sheet includes a second portion coated with an electrode active material.
[0025] Preferably, a plurality of tabs are provided on the electrode sheet in the first portion of the electrode sheet extending laterally from the free edge.
[0026] Preferably, a longitudinal trajectory is provided within a first portion of the electrode sheet, and the thickness of the electrode sheet decreases along this longitudinal trajectory.
[0027] The applicant has demonstrated that the reduction in the thickness of the electrode sheet along the longitudinal trajectory can actually create a preferred fold line for the tab, which tends to define a hinge line along which the tab folds when subjected to folding pressure outside the plane defined by the electrode sheet.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] Preferably, the thickness of the electrode sheet is at least two orders of magnitude smaller than the lateral dimension of the electrode sheet.
[0033] Preferably, the lateral dimension of the electrode sheet is at least one order of magnitude smaller than the longitudinal dimension of the electrode sheet.
[0034] Preferably, the second electrode portion is transversely continuous with the first electrode portion.
[0035] Preferably, cutting multiple tabs includes setting multiple tabs, wherein each tab extends from a lateral outer end to a lateral inner end.
[0036] Preferably, the outer lateral end of the tab coincides with the longitudinal free edge of the electrode sheet.
[0037] Preferably, the longitudinal trajectory is positioned between the outer and inner lateral ends of the electrode tab.
[0038] Preferably, the longitudinal trajectory passes through the lateral inner end of the electrode tab.
[0039] Optionally, the longitudinal trajectory passes through the lateral inner end of the electrode tab.
[0040] Preferably, the plurality of tabs are contained in the first portion of the electrode sheet.
[0041] Preferably, the lateral inner ends of the plurality of tabs are aligned with each other along a straight line.
[0042] Preferably, the straight line extends longitudinally.
[0043] Preferably, the longitudinal trajectory is parallel to the straight line.
[0044] Preferably, when the longitudinal trajectory passes through the inner lateral end of the tab, the longitudinal trajectory coincides with the straight line.
[0045] Preferably, the longitudinal trajectory includes a weakened portion.
[0046] Preferably, the weakened portion is the portion where the electrode sheet thickness is reduced.
[0047] In some implementations, the weakened portions are preferably continuous with each other.
[0048] In these implementations, preferably, the weakened portions follow each other longitudinally along the longitudinal trajectory.
[0049] In these implementations, preferably, the weakened portions are longitudinally continuous to provide a single continuous weakened portion.
[0050] In other embodiments, preferably, the longitudinal trajectory includes a weakened portion and a non-weakened portion.
[0051] Preferably, the non-weakened portion alternates with the weakened portion.
[0052] Preferably, the weakened portions have equal lengths in the longitudinal direction.
[0053] Preferably, the non-weakened portions have equal lengths in the longitudinal direction.
[0054] Preferably, the weakened portion and the non-weakened portion have equal lengths in the longitudinal direction.
[0055] Preferably, reducing the thickness of the electrode sheet includes reducing the thickness of the electrode sheet by weakening all the weakened portions along the longitudinal trajectory.
[0056] Preferably, reducing the thickness of the electrode sheet includes reducing the thickness of the electrode sheet only along the weakened portion of the longitudinal trajectory.
[0057] Preferably, reducing the thickness of the electrode sheet includes reducing the thickness of the electrode sheet by 5% to 70% along at least some weakened portions.
[0058] Preferably, reducing the thickness of the electrode sheet includes reducing the thickness of the electrode sheet by 5% to 70% along some weakened portions and reducing the thickness of the electrode sheet by 5% to 100% along other weakened portions.
[0059] Preferably, reducing the thickness of the electrode sheet by 100% includes providing a through groove in the electrode sheet.
[0060] Preferably, reducing the thickness of the electrode sheet involves reducing the thickness of the electrode sheet by 5% to 70% along all the weakened portions.
[0061] Preferably, reducing the thickness of the electrode sheet includes reducing the thickness of the electrode sheet by 5% to 50% along all the weakened portions.
[0062] Preferably, reducing the thickness of the electrode sheet includes reducing the thickness of the electrode sheet by 10% to 40% along all the weakened portions.
[0063] Preferably, reducing the thickness of the electrode sheet includes reducing the thickness of the electrode sheet by 10% to 20% along all the weakened portions.
[0064] Preferably, the thickness of the electrode sheet is reduced only on one surface of the electrode sheet in relation to the weakened portion.
[0065] Preferably, the reduction in electrode thickness is the same for all weakened portions.
[0066] In some implementations, preferably, the reduction in electrode thickness is not uniform across all weakened portions.
[0067] Preferably, reducing the thickness of the electrode sheet includes providing through grooves on the electrode sheet corresponding to at least some weakened portions.
[0068] In some embodiments that include weakened and non-weakened portions, reducing the thickness of the electrode sheet includes providing through grooves in the electrode sheet corresponding to all the weakened portions.
[0069] Preferably, when no non-weakened portions are provided, reducing the thickness of the electrode sheet includes providing through grooves in the electrode sheet that correspond only to some of the weakened portions.
[0070] Preferably, reducing the thickness of the electrode sheet involves keeping the non-weakened portion unchanged.
[0071] Preferably, the dimension of the weakened portion in the lateral direction is about half to about five times the thickness of the electrode sheet.
[0072] Preferably, the dimension of the weakened portion in the lateral direction is from the electrode sheet thickness to twice the electrode sheet thickness.
[0073] Preferably, each electrode includes an upper edge and two opposing side edges.
[0074] Preferably, the upper edge is aligned with the free edge of the electrode sheet, and the side edges extend laterally from the upper edge.
[0075] In some implementations, preferably, the weakened portion alternates with the unweakened portion along a longitudinal trajectory.
[0076] In some of these implementations, preferably, when the longitudinal trajectory is inserted between the lateral outer end and the lateral inner end of the electrode tab, no weakened portion reaches the side edge of the electrode tab.
[0077] Preferably, the thickness of the electrode sheet is reduced by removing material from the electrode sheet.
[0078] The removal of this material can preferably be achieved through mechanical removal of the material by vaporization or ablation.
[0079] The applicant has indeed demonstrated that reducing the thickness of the electrode sheet by crushing the material is not very effective in forming the preferred fold lines of the tab when subjected to folding pressure outside the plane defined by the electrode sheet.
[0080] Preferably, reducing the thickness of the electrode sheet includes guiding the laser beam along the longitudinal trajectory onto the electrode sheet and onto the weakened portion.
[0081] 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.
[0082] Preferably, the electrode sheet is conveyed longitudinally.
[0083] Preferably, the laser beam is used to cut multiple tabs.
[0084] Preferably, the reduction in electrode thickness is performed during the conveying of the electrode sheet along the conveying direction.
[0085] Preferably, the thickness of the electrode sheet is reduced using the same laser used to cut multiple tabs.
[0086] Preferably, the reduction of the electrode sheet thickness is carried out substantially simultaneously with the cutting of multiple electrode tabs.
[0087] Preferably, the cutting of multiple tabs is performed by applying the laser at a first power, at least when the thickness of the electrode sheet is reduced by less than 100%, and the reduction of the electrode sheet thickness is performed by applying the laser at a second power; the first power is greater than the second power.
[0088] 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:
[0089] - Figure 1 A front view of a portion of an electrode for an electrochemical cell according to the present invention;
[0090] - Figures 2 to 4 for Figure 1 A front view of a possible alternative implementation scheme for the middle electrode;
[0091] - 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
[0092] - 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.
[0093] 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.
[0094] Electrode 10 can be used to manufacture the cathode or anode of an electrochemical cell.
[0095] 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.
[0096] 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.
[0097] 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.
[0098] The electrode sheet 11 also includes an active material for the electrode 14 applied to one or both surfaces of the current collector 13.
[0099] 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.
[0100] like Figure 1 As illustrated, the active material used for electrode 14 only partially covers current collector 13.
[0101] 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 extend longitudinally substantially over the entire length L of the electrode sheet 11.
[0102] 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.
[0103] 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.
[0104] The electrode sheet 11 includes a plurality of tabs 17 disposed in the first electrode portion 15.
[0105] like Figure 1 As shown, the tab 17 extends laterally from the free edge 12a toward the second portion 16, but does not reach the second portion 16 of the electrode sheet 11.
[0106] The tabs 17 follow each other longitudinally along the electrode plates 11.
[0107] Each tab 17 includes an upper edge 18 and two opposing side edges 19. The upper edge 18 is substantially aligned with the free edge 12a of the electrode sheet 11, and the side edges 19 extend laterally from the upper edge 18.
[0108] The upper edge 18 of each tab 17 defines the lateral outer end 17a of the tab 17, and the point on the lateral side edge 19 further away from the upper edge 18 defines the lateral inner end 17b of the tab 17.
[0109] like Figure 1 As shown, the lateral inner ends 17b of the tabs 17 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.
[0110] In a preferred embodiment of the invention, the side edge 19 of the first electrode 17 is longitudinally adjacent to the side edge 19 of the second adjacent electrode 17. In this embodiment, as... Figure 1 As shown, the distance between each tab 17 and the adjacent tab 17 is much smaller than the width of the tab 17 in the longitudinal direction. The distance between two adjacent tabs 17 in the longitudinal direction is equal to that between each other.
[0111] Electrode 10 includes a longitudinal trajectory 20 that extends entirely within a first portion 15 of electrode sheet 11, and the thickness of electrode sheet 11 decreases along the longitudinal trajectory 20 relative to the thickness of electrode sheet 11 outside the longitudinal trajectory 20.
[0112] The longitudinal trajectory 20 is essentially straight. The longitudinal trajectory 20 is essentially parallel to the longitudinal free edge 12a.
[0113] The longitudinal trajectory 20 may include only the weakened portion 21, or it may include both the weakened portion 21 and the non-weakened portion 22.
[0114] The weakened portion 21 is the portion in the longitudinal trajectory 20 where the thickness of the electrode sheet 11 decreases, while the non-weakened portion 22 is the portion in the longitudinal trajectory 20 where the thickness of the electrode sheet 11 remains unchanged.
[0115] exist Figure 1 In the implementation scheme, the longitudinal trajectory 20 includes a weakened portion 21 and a non-weakened portion 22.
[0116] The weakened portion 21 alternates with the unweakened portion 22 along the longitudinal trajectory 20.
[0117] The weakened portion 21 has an equal length in the longitudinal direction.
[0118] The non-weakened portions 22 have equal lengths in the longitudinal direction.
[0119] At least one weakened portion 21 has a longitudinal length greater than the longitudinal length of any non-weakened portion 22.
[0120] The length of any weakened part 21 in the longitudinal direction is greater than the length of any non-weakened part 22 in the longitudinal direction.
[0121] Only some of the weakened portions 21 intersect with the side edges 19 of the corresponding tabs 17. In other words, the length of the weakened portions 21 in the longitudinal direction is less than the distance between the two side edges 19 of the tabs 17 measured in the longitudinal direction.
[0122] The longitudinal trajectory 20 is located between the outer transverse end 17a and the inner transverse end 17b of the tab 17.
[0123] Along the weakened portion 21, the thickness of the electrode sheet 11 is reduced by 5% to 70%, for example, by 8% to 22%.
[0124] Along all the weakened portions 21, the thickness of the electrode sheet 11 decreases by the same amount.
[0125] Optionally, the thickness of the electrode sheet 11 is reduced by 100% along the weakened portion 21. In this case, the thickness of the electrode sheet 11 is essentially zero through the through groove on the electrode sheet 11 corresponding to the weakened portion 21.
[0126] Optionally, along certain weakened portions 21, the thickness of the electrode sheet 11 is reduced by 5% to 70%, for example, by 8% to 22%, and in other weakened portions, the thickness of the electrode sheet 11 is reduced by 100% through through grooves.
[0127] In some such alternative embodiments, the longitudinal trajectory 20 passes through the lateral inner end 17b of the tab 17. In these embodiments, the longitudinal trajectory 20 coincides with the straight line R aligned with the lateral inner end 17b of the tab 17.
[0128] In an alternative implementation, the length of the weakened portion 21 in the longitudinal direction is equal to the length of the unweakened portion 22 in the longitudinal direction.
[0129] In some such alternative embodiments, the length of the weakened portion 21 in the longitudinal direction is equal to the distance between the two side edges 19 of the tab 17 measured in the longitudinal direction.
[0130] In some such alternative implementations, all the weakened portions 21 intersect with the corresponding side edges 19 of the corresponding tabs 17.
[0131] exist Figure 2 In the implementation scheme, the longitudinal trajectory 20 includes only the weakened portion 21.
[0132] The weakened portions 21 are continuous with each other and essentially form a single weakened portion 21.
[0133] The weakened portion 21 intersects with the corresponding side edge 19 of the corresponding tab 17.
[0134] The longitudinal trajectory 20 is located between the outer transverse end 17a and the inner transverse end 17b of the tab 17.
[0135] Along the weakened portion 21, the thickness of the electrode sheet is reduced by 5% to 70%, for example, by 8% to 22%.
[0136] Along all the weakened sections 21, the thickness of the electrode sheet decreases by the same amount.
[0137] In some such alternative embodiments, the longitudinal trajectory 20 passes through the lateral inner end 17b of the tab 17. In these embodiments, the longitudinal trajectory 20 coincides with the straight line R aligned with the lateral inner end 17b of the tab 17.
[0138] exist Figure 3 In the implementation example, the longitudinal trajectory 20 includes a weakened portion 21 and a non-weakened portion 22.
[0139] The weakened portion 21 alternates with the unweakened portion 22 along the longitudinal trajectory 20.
[0140] The weakened portion 21 has an equal length in the longitudinal direction.
[0141] The non-weakened portions 22 have equal lengths in the longitudinal direction.
[0142] At least one weakened portion 21 has a longitudinal length greater than the longitudinal length of any non-weakened portion 22.
[0143] The length of any weakened part 21 in the longitudinal direction is greater than the length of any non-weakened part 22 in the longitudinal direction.
[0144] All the weakened portions 21 intersect with the corresponding side edges 19 of the corresponding tabs 17.
[0145] The longitudinal trajectory 20 passes through the inner lateral end 17b of the tab 17. The longitudinal trajectory 20 coincides with the straight line R aligned with the inner lateral end 17b of the tab 17.
[0146] Along the weakened portion 21, the thickness of the electrode sheet 11 is reduced by 5% to 70%, for example, by 8% to 22%.
[0147] Along all the weakened portions 21, the thickness of the electrode sheet 11 decreases by the same amount.
[0148] Optionally, the thickness of the electrode sheet 11 is reduced by 100% along the weakened portion 21. In this case, the thickness of the electrode sheet 11 is essentially zero through the through groove on the electrode sheet 11 corresponding to the weakened portion 21.
[0149] Optionally, along certain weakened portions 21, the thickness of the electrode sheet 11 is reduced by 5% to 70%, for example, by 8% to 22%, and in other weakened portions, the thickness of the electrode sheet 11 is reduced by 100% through through grooves.
[0150] In some such alternative embodiments, the longitudinal trajectory 20 is located between the lateral outer end 17a and the lateral inner end 17b of the tab 17.
[0151] In an alternative implementation, the length of the weakened portion 21 in the longitudinal direction is equal to the length of the unweakened portion 22 in the longitudinal direction.
[0152] In some such alternative embodiments, the length of the weakened portion 21 in the longitudinal direction is equal to the distance between the two side edges 19 of the tab 17 measured in the longitudinal direction.
[0153] In some such alternative embodiments, only certain weakened portions 21 intersect with the side edges 19 of the corresponding tabs 17. In other words, the length of the weakened portions 21 in the longitudinal direction is less than the distance between the two side edges 19 of the tabs 17 measured in the longitudinal direction.
[0154] exist Figure 4 In the implementation example, the longitudinal trajectory 20 includes a weakened portion 21 and a non-weakened portion 22.
[0155] The weakened portion 21 alternates with the unweakened portion 22 along the longitudinal trajectory 20.
[0156] The weakened portion 21 has an equal length in the longitudinal direction.
[0157] The non-weakened portions 22 have equal lengths in the longitudinal direction.
[0158] The length of the weakened portion 21 in the longitudinal direction is less than the distance between the two side edges 19 of the tab 17 measured in the longitudinal direction.
[0159] At least one weakened portion 21 has a longitudinal length greater than the longitudinal length of any non-weakened portion 22.
[0160] The length of any weakened part 21 in the longitudinal direction is greater than the length of any non-weakened part 22 in the longitudinal direction.
[0161] The unweakened portion 21 intersects with the side edge 19 of the tab 17.
[0162] The longitudinal trajectory 20 passes through the inner lateral end 17b of the tab 17. The longitudinal trajectory 20 coincides with the straight line R aligned with the inner lateral end 17b of the tab 17.
[0163] Along the weakened portion 21, the thickness of the electrode sheet 11 is reduced by 5% to 70%, for example, by 8% to 22%.
[0164] Along all the weakened portions 21, the thickness of the electrode sheet 11 decreases by the same amount.
[0165] Optionally, the thickness of the electrode sheet 11 is reduced by 100% along the weakened portion 21. In this case, the thickness of the electrode sheet 11 is essentially zero through the through groove on the electrode sheet 11 corresponding to the weakened portion 21.
[0166] Optionally, along certain weakened portions 21, the thickness of the electrode sheet 11 is reduced by 5% to 70%, for example, by 8% to 22%, and in other weakened portions, the thickness of the electrode sheet 11 is reduced by 100% through through grooves.
[0167] In some alternative embodiments, the longitudinal track 20 is inserted between the lateral outer end 17a and the lateral inner end 17b of the tab 17.
[0168] In an alternative implementation, the length of the weakened portion 21 in the longitudinal direction is equal to the length of the unweakened portion 22 in the longitudinal direction.
[0169] In all the embodiments discussed above, multiple tabs 17, longitudinal tracks 20, weakened portions 21 and non-weakened portions 22 have been described relative to a single free edge 12a of electrode sheet 11.
[0170] In other embodiments, all the features associated with the multiple tabs 17, the longitudinal trajectory 20, the weakened portion 21 and the unweakened portion 22 may also be present at another longitudinal free edge 12b of the electrode sheet 11.
[0171] 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.
[0172] 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.
[0173] 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.
[0174] 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.
[0175] These operations can be performed on one surface of the current collector 13 or on both surfaces of the current collector 13.
[0176] The electrode sheet 11 thus obtained can be wound up to form an electrode sheet roll 23 for temporary storage or direct use.
[0177] 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).
[0178] 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.
[0179] When the electrode sheet 11 travels along the conveying path P in the conveying direction T, the laser device 24 is activated to reduce the thickness of the electrode sheet 11 along the longitudinal trajectory 20 and cut multiple tabs 17.
[0180] The operations of reducing the thickness of the electrode sheet 11 and making the tab 17 are performed "in dynamic", that is, while the electrode sheet 11 is moving along the transport direction T.
[0181] 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.
[0182] The laser beam's focal point travels along the processing trajectory 27 on the electrode sheet 11, repeating this trajectory substantially multiple times to reduce the thickness of the electrode sheet 11 and cut the tab 17 to the desired length along the electrode sheet 11.
[0183] 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 proceeds along a meandering path 31 (composed of bends and straight segments 32) spanning the first straight segment 29 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.
[0184] Make the first straight segment 29 of the processing trajectory 27 coincide with the longitudinal trajectory 20 whose thickness is to be reduced, make the second straight segment 30 of the processing trajectory 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 side edge 18 of the tab 17 to be set.
[0185] By modulating the power of the laser oscillator 25 between a minimum power equal to zero and a maximum power, the tab 17 can be cut and the thickness of the electrode sheet 11 can be reduced along the weakened portion 21.
[0186] Specifically, in order to cut the tab 17, 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 31 of the processing trajectory 27.
[0187] When the reduction in the thickness of the electrode sheet corresponding to the weakened portion 21 is less than 100%, the power of the laser oscillator 25 is set to a second power that is sufficient to reduce the thickness of the electrode sheet 11 by the amount required. This second power is used when the focus of the laser beam travels along the first straight segment 29 of the processing trajectory 27 and corresponds to the weakened portion 21.
[0188] When the thickness of the electrode sheet remains constant in the unweakened portion 22, the power of the laser oscillator 25 is set to zero. This zero power value is used when the focus of the laser beam travels along the first straight segment 29 of the processing trajectory 27 and corresponds to the unweakened segment 22. This zero power value is also used when the focus of the laser beam travels along the curved segment of the processing trajectory 27.
[0189] When tabs 17 and weakening portions 21 are provided on the processed portion of electrode sheet 11, electrode sheet 11 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). Multiple tabs (17) are cut on the electrode sheet (11) in the first part (15) of the electrode sheet; The thickness of the electrode sheet (11) is reduced along the longitudinal trajectory (20) contained in the first part (15) of the electrode sheet (11).
2. The method of claim 1, wherein cutting the plurality of tabs (17) comprises setting the plurality of tabs (17), wherein each tab (17) extends from a lateral outer end (17a) to a lateral inner end (17b).
3. The method according to claim 2, wherein the transverse inner ends (17b) of the plurality of tabs (17) are aligned with each other along a straight line (R), and the longitudinal trajectory (20) is parallel to the straight line (R).
4. The method according to any one of the preceding claims, wherein the longitudinal trajectory (20) includes a weakened portion (21).
5. The method according to claim 4, wherein the weakened portions (21) are continuous with each other.
6. The method according to any one of claims 1 to 4, wherein the longitudinal trajectory (20) comprises a weakened portion (21) and a non-weakened portion (22).
7. The method according to any one of claims 4 to 6, wherein reducing the thickness of the electrode sheet (11) comprises reducing the thickness of the electrode sheet (11) by 5% to 70% along at least some weakened portions (21).
8. The method according to claim 7, wherein reducing the thickness of the electrode sheet (11) comprises reducing the thickness of the electrode sheet (11) along all of the weakened portions (21) of the longitudinal trajectory (20).
9. The method according to claim 7, wherein reducing the thickness of the electrode sheet (11) comprises reducing the thickness of the electrode sheet (11) by 5% to 70% along certain weakened portions (21) and reducing the thickness of the electrode sheet (11) by 5% to 100% along other weakened portions (21).
10. The method of claim 6, wherein each tab (17) includes an upper edge (18) and two opposing side edges (19), wherein the upper edge (18) is aligned with the free edge (12a) of the electrode sheet (11), and the side edges (19) extend laterally from the upper edge (18); the weakened portion (21) alternates with the non-weakened portion (22) along the longitudinal trajectory (20); and no weakened portion (21) reaches the side edge (19) of the tab (17).
11. The method according to any one of claims 2 to 10, wherein the longitudinal trajectory (20) is inserted between the lateral outer end (17a) and the lateral inner end (17b) of the tab (17).
12. The method according to any one of claims 2 to 10, wherein the longitudinal trajectory (20) passes through the transverse inner end (17b) of the tab (17).
13. The method of claim 6, wherein reducing the thickness of the electrode sheet (11) includes keeping the non-weakened portion (22) unchanged.
14. The method according to any one of claims 4 to 9, wherein reducing the thickness of the electrode sheet (11) and cutting the plurality of tabs (17) comprises guiding a laser beam onto the electrode sheet (11), and wherein reducing the thickness of the electrode sheet (11) is performed while the electrode sheet (11) is being transported along the transport direction (T).
15. The method of claim 14, wherein cutting the plurality of tabs (17) is performed by applying a laser at a first power, and wherein reducing the thickness of the electrode sheet (11) is performed by applying a laser at a second power; the first power being greater than the second power.
16. An electrode (10) for use in an electrochemical cell, comprising: 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 tabs (17) extend laterally from the free edge (12a) on the electrode sheet (11) in the first portion (15) of the electrode sheet; A longitudinal trajectory (20) is contained in the first portion (15) of the electrode sheet (11), and the thickness of the electrode sheet (11) decreases along the longitudinal trajectory (20).
17. The electrode according to claim 16, wherein each of the plurality of tabs (17) extends from a laterally outer end (17a) to a laterally inner end (17b).
18. The electrode according to claim 17, wherein the transverse inner ends (17b) of the tabs (17) of the plurality of tabs (17) are aligned with each other along a straight line (R), and the longitudinal trajectory (20) is parallel to the straight line (R).
19. The electrode according to any one of claims 16 to 18, wherein the longitudinal trajectory (20) includes a weakened portion (21).
20. The electrode according to claim 19, wherein the weakened portions (21) are continuous with each other.
21. The electrode according to any one of claims 16 to 19, wherein the longitudinal trajectory (20) comprises a weakened portion (21) and a non-weakened portion (22).
22. The electrode according to any one of claims 19 to 21, wherein the thickness of the electrode sheet (11) is reduced by 5% to 70% along at least some of the weakened portions (21).
23. The electrode according to claim 22, wherein the thickness of the electrode sheet (11) decreases along all of the weakened portions (21) of the longitudinal trajectory (20).
24. The electrode according to claim 22, wherein the thickness of the electrode sheet (11) decreases by 5% to 70% along some weakened portions (21) and by 5% to 100% along other weakened portions (21).
25. The electrode of claim 17, wherein each tab (17) comprises an upper edge (18) and two opposing side edges (19), wherein the upper edge (18) is aligned with the free edge (12a) of the electrode sheet (11), and the side edges (19) extend laterally from the upper edge (18); the weakened portion (21) alternates with the non-weakened portion (22) along the longitudinal trajectory (20); no weakened portion (21) reaches the side edge (19) of the tab (17).
26. The electrode according to any one of claims 17 to 25, wherein the longitudinal trajectory (20) is inserted between the lateral outer end (17a) and the lateral inner end (17b) of the tab (17).
27. The electrode according to any one of claims 17 to 25, wherein the longitudinal trajectory (20) passes through the transverse inner end (17b) of the tab (17).
28. The electrode according to claim 21, wherein the thickness of the electrode sheet (11) remains constant at the non-weakened portion (22).