Preparation process of lithium battery cell positive plate and lithium battery cell

Abstract

The invention relates to a preparation process of a lithium battery cell positive plate and the positive plate, and the preparation process comprises the following specific steps: slurry mixing, coating and rolling: coating according to a designed pole plate structure after slurry mixing, then rolling the coated positive plate, slitting, and cutting a foil tab by laser / punching the foil tab by a die to prepare the positive plate. According to the invention, the distribution sequence and width of the ceramic adhesive and the positive electrode powder layer on the surface of the aluminum foil substrate of the positive electrode plate are changed, so that the outermost side of the aluminum foil substrate is a ceramic edge / powder line edge, and the blank foil tab structure is arranged on the inner side instead of the initial outer side in the width direction of the electrode plate; the strip breaking risk in the rolling process of a thin aluminum foil base material, especially a thin foil positive plate smaller than or equal to 9 microns, is improved, and the cutting strip cutting phenomenon caused by empty foil wrinkles in the rolling process is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to a preparation process of a lithium battery cell positive electrode sheet and a lithium battery cell. Background Art

[0002] With the development of lithium-ion batteries, customers have higher and higher requirements for the energy density and rate performance of battery cells. Compared with the conventional center-tab structure, the rate performance of multi-tab winding structure and laminated structure battery cells is better. In order to ensure the safety performance of multi-tab winding battery cells and laminated structure battery cells, usually an insulating glue (non-ceramic glue) or a safety coating (usually ceramic glue) or protective tape is applied on one side of the positive electrode tab surface. The manufacturing process of each method is different. Taking the commonly used and mature ceramic coating as an example, the zebra coating method is usually adopted during the production. The two sides of the positive electrode powder layer contain ceramic glue to form a positive electrode powder unit. The zebra coating method refers to the intermittent coating of several positive electrode powder units. This technology belongs to the conventional technology in this field. Coating such as Fig.16 , where 1-1 or 1-2 or 1-3 is a blank foil area, 2-1 or 2-2 or 2-3 or 2-4 is a ceramic glue layer, and 3-1 or 3-2 is a positive electrode powder layer. The coated electrode will pass through a rolling roller to roll the electrode. The material elongation rates of the three different areas are different, and the thickness of the electrode is different. During the rolling process, the 1-1 and 1-3 areas are prone to belt breakage, and the 1-2 area is prone to rolling wrinkles. In the multi-electrode winding structure, the rolled electrode is divided into strips in the middle of the 1-2 area. The striping diagram is shown in the figure. Fig.17 After the pole piece is stripped, the blank foil on both sides of the pole piece will be laser cut into foil tabs by laser cutting equipment. After the foil tabs are cut, the pole piece will be stripped into two. Fig.18 In the laminated structure, the rolled pole pieces are divided into strips in the middle of the 1-2, 3-1, and 3-2 regions. The striping diagram is shown in Fig.19 After the pole pieces are stripped, they will be punched out using a punching die.

[0003] For the existing film making technology, since the pole piece is distributed in the width direction with aluminum foil 1-1-ceramic 2-1-pole powder 3-1-ceramic 2-2-aluminum foil 1-2-ceramic 2-3-pole powder 3-2-ceramic 2-4-aluminum foil 1-3, the edge aluminum foil and the center aluminum foil of this design need to be used as the lead-out foil pole ears of the pole piece. The width of the edge aluminum foil 1-1 and 1-3 is 5mm-15mm, and the width of the center aluminum foil 1-2 is 10mm-30mm. Due to the different elongation rates of different material areas (empty aluminum foil area, aluminum foil area coated with ceramic, and aluminum foil area coated with powder), and the different friction forces of the materials on the rollers, the outer aluminum foil area is most likely to break during the rolling process. In addition, the width of the central aluminum foil is wider, and it is easy to wrinkle during the rolling process. The wrinkled foil will also cause the strip to break during the cutting process. As the foil tends to be thinner, the strip breaking rate of the pole piece is seriously improved. In order to improve the tape breakage situation, more and more equipment is currently equipped with foil pre-stretching devices. This method has improved the tape breakage situation during rolling to a certain extent. However, for thinner foils less than or equal to 9μm, tape breakage during rolling and cutting still occurs frequently. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the above-mentioned technology and to provide a process for preparing a positive electrode sheet of a lithium battery cell and a lithium battery cell, which can solve the problem of broken strips during rolling and cutting of the positive electrode sheet.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a preparation process of a positive electrode sheet of a lithium battery cell, the specific steps are as follows: Step 1, slurry mixing: slurry mixing of positive electrode powder according to the process requirement ratio; Step 2, coating: using a conventional zebra coating process on one or both sides of the aluminum foil substrate, coating from left to right along the width direction of the aluminum foil substrate, ceramic glue layer-positive electrode powder layer or positive electrode powder layer-ceramic glue layer, to form two positive electrode sheet structures with different coating arrangements; Step 3, rolling: rolling the coated positive electrode sheet; Step 4: Pole sheet stripping: stripping the rolled positive electrode sheet according to the pole sheet width required by the process; Step 5, cutting the foil tabs: according to the position and number of the foil tabs, the foil tabs are cut for the stripped electrode. Laser cutting of foil tabs: For the narrow strip pole piece structure of the multi-pole tab structure battery cell, a single laser is used to cut the foil tabs; for the wide strip pole piece structure, dual lasers are used to simultaneously cut the tabs on both sides, and then the wide strip pole piece is stripped twice to make the positive pole piece; Die punching foil tabs: The foil tabs of laminated structure cells are cut, that is, the stripped pole pieces are punched out with a die-cutting knife to make positive pole pieces.

[0006] Step 2) When the coating method adopted for the positive electrode sheet structure is: ceramic glue layer-positive electrode powder layer, the specific structure of the positive electrode sheet is ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer; or, ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer; or, ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer, this coating form is related to the size of the battery cell and the overall width of the rolling equipment, that is, it satisfies the following rule: the number of blank foil strips in the middle is x, the number of positive electrode powder strips is x+1, and the number of ceramic glue strips is 2(x+1); Further, when the coating method adopted by the positive electrode sheet structure is positive electrode powder layer-ceramic glue layer, the specific structure of the positive electrode sheet is positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer; or, positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer; or, positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer. This coating form is related to the size of the battery cell and the overall width of the rolling equipment, that is, it satisfies the following rule: if the number of blank foil strips in the middle is x, the number of positive electrode powder strips is x+1, and the number of ceramic glue strips is 2x.

[0007] Furthermore, the width of the blank foil area is 5-15 mm.

[0008] Furthermore, the width of the positive electrode powder layer: the width L1' / L2' of the middle positive electrode powder layer and the width L1 / L2 of the outermost positive electrode powder layers satisfy the following relationship: L1'=2L1-(0~10)mm / L2'=2L2 Further, the pole piece stripping in step 4 includes a pole piece structure of a multi-electrode structure battery cell stripping, and the stripping structure includes one-to-two, that is, a side narrow strip area-a side narrow strip area, or, one-to-three, that is, a side narrow strip area-a wide strip area-a side narrow strip area, or, one-to-four, that is, a side narrow strip area-a wide strip area-a side narrow strip area, or, one-to-n, that is, a side narrow strip area-a (n-2) wide strip area-a side narrow strip area, and the cutting line of the slitting knife is on the center line of the blank foil; The electrode structure of the laminated structure battery cell is divided into strips, and the strip structure includes one-to-one, that is, the side narrow strip area-the side narrow strip area is an overall m structure, or one-to-two, that is, a 2m structure, or one-to-three, that is, a 3m structure, or one-to-n, that is, an nm structure, and the cutting line of the cutting knife is on the center line of the middle positive electrode powder, where n is 1, 2, 3...n.

[0009] Furthermore, the ceramic glue layer and the positive electrode powder layer are closely arranged side by side or intersecting and overlapping, and the intersection and overlap size is 0.05-1mm.

[0010] Furthermore, the width of the ceramic adhesive layer is 1-4 mm.

[0011] Furthermore, the thickness of one side of the ceramic glue layer is less than or equal to the thickness of one side of the positive electrode powder layer; and the total thickness of both sides of the ceramic glue layer is less than or equal to the total thickness of both sides of the positive electrode powder layer.

[0012] Furthermore, a lithium battery cell is a multi-electrode wound cell or a stacked cell made of a positive electrode sheet prepared using the preparation process.

[0013] Beneficial effects: Compared with the prior art, the present invention solves the problem of tape breakage during rolling and cutting of the prior art multi-electrode wound battery cell pole pieces or laminated battery cell positive electrode pieces, especially for thinner foils less than or equal to 9μm, the tape breakage phenomenon during rolling and cutting is greatly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic structural diagram of a positive electrode sheet embodiment 1 of the present invention; Figure 2 is a schematic diagram of the coating structure of the positive electrode sheet of Example 1-1; Figure 3 is a schematic diagram of the coating structure of the positive electrode sheet of Example 1-2; Figure 4 is a schematic diagram of the laminated positive electrode strip structure of Example 1; Figure 5 Schematic diagram of the multi-electrode positive electrode strip structure of Example 1; Figure 6 It is a schematic structural diagram of a positive electrode sheet embodiment 2 of the present invention; Figure 7 is a schematic diagram of the coating structure of the positive electrode sheet of Example 2-1; Figure 8 is a schematic diagram of the coating structure of the positive electrode sheet of Example 2-2; Fig. 9 is a schematic diagram of the laminated positive electrode strip structure of Example 2; Fig.10 Schematic diagram of the multi-electrode positive electrode strip structure of Example 2; Fig.11 It is a schematic diagram of the structure of the positive electrode die punching; Fig.12 This is a schematic diagram of the structure of the edge strip after laser cutting of the positive electrode sheet; Fig.13 This is a schematic diagram of the structure of the middle strip of the positive electrode after laser cutting; Fig.14 This is a schematic diagram of the strip structure of the middle strip after the positive electrode sheet is laser cut; Fig.15 This is a schematic diagram of the structure of the positive electrode after laser cutting and striping; Fig.16 This is a schematic diagram of the structure of the positive electrode sheet before rolling in the existing scheme; Fig.17 This is a schematic diagram of cutting the positive electrode sheet of the existing solution; Fig.18 This is a schematic diagram of the pole piece after laser cutting in the existing solution; Fig.19 This is a schematic diagram of the existing laminated pole stripping scheme.

[0015] In the figure: 1. Aluminum foil substrate, 2. Ceramic glue, 3. Positive electrode powder layer, A refers to a unit body of ceramic after being divided into strips on the outside. B is a striped unit on the outside of the powder line. 1-1, 1-2, and 1-3 are aluminum foil areas in three different regions on the electrode. 2-1, 2-2, 2-3, 2-4, 2-5, 2-6, 2-7, and 2-8 are ceramic adhesive layers in eight different areas on the pole piece. 3-1, 3-2, 3-3, and 3-4 are the positive electrode material areas in four different areas on the electrode. 1-1a and 1-1b are the aluminum foil areas corresponding to the stripping of 1-1. 1-2a and 1-2b are the aluminum foil areas corresponding to 1-2 stripping. 1-1a1, 1-1a2, 1-1a3, 1-1a4…are the tabs cut out by laser on the aluminum foil of 1-1a. 1-1b1, 1-1b2, 1-1b3, 1-1b4…are the tabs cut out by laser on the 1-1b aluminum foil. 1-2a1, 1-2a2, 1-2a3, 1-2a4, ... are the pole ears laser cut out from the aluminum foil of 1-2a. DETAILED DESCRIPTION

[0016] In order to be able to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present invention, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the art without making creative work are within the scope of protection of the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0017] In the various embodiments of the present invention, for the convenience of description and not to limit the present invention, the term "connection" used in the patent application specification and claims of the present invention is not limited to physical or mechanical connection, but may include electrical connection, whether direct or indirect. "Up", "down", "below", "left", "right", etc. are only used to indicate relative position relationship. When the absolute position of the described object changes, the relative position relationship also changes accordingly.

[0018] See the attached drawings for details. This embodiment provides a preparation process for the positive electrode sheet of a lithium battery cell. The distribution order and width of the ceramic glue and positive electrode powder layer on the surface of the positive electrode sheet aluminum foil substrate are changed, and the outermost blank foil of the aluminum foil substrate is cut before rolling, so that the outermost side of the aluminum foil substrate is the powder line edge, and the blank foil structure initially arranged on the outside along the width direction of the electrode sheet is changed to the blank foil structure arranged on the inside, thereby improving the risk of breaking during the rolling process of the aluminum foil substrate. The specific steps are as follows: Step 1, slurry mixing: slurry mixing of positive electrode powder according to the process requirement ratio; Step 2, coating: using a conventional zebra coating process on one or both sides of the aluminum foil substrate, coating from left to right along the width direction of the aluminum foil substrate, ceramic glue layer-positive electrode powder layer or positive electrode powder layer-ceramic glue layer, to form two positive electrode sheet structures with different coating arrangements; Step 3, rolling: rolling the coated positive electrode sheet; Step 4: Pole sheet stripping: stripping the rolled positive electrode sheet according to the pole sheet width required by the process; Step 5, cutting the foil tabs: according to the position and number of the foil tabs, the foil tabs are cut for the stripped electrode. Laser cutting of foil tabs: For the narrow strip pole piece structure of the multi-pole tab structure battery cell, a single laser is used to cut the foil tabs; for the wide strip pole piece structure, dual lasers are used to simultaneously cut the tabs on both sides, and then the wide strip pole piece is stripped twice to make the positive pole piece; Die punching foil tabs: The foil tabs of laminated structure cells are cut, that is, the stripped pole pieces are punched out with a die-cutting knife to make positive pole pieces.

[0019] The preferred scheme of this embodiment is that, in step 2), the coating method adopted by the positive electrode sheet structure is: ceramic glue layer-positive electrode powder layer, and the specific structure of the positive electrode sheet is ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer; or, ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer ; or, ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer. This coating form is related to the size of the battery cell and the overall width of the rolling equipment, that is, it satisfies the following rule: the number of blank foil strips in the middle is x, the number of positive electrode powder strips is x+1, and the number of ceramic glue strips is 2(x+1); When the coating method adopted for the positive electrode sheet structure is positive electrode powder layer-ceramic glue layer, the specific structure of the positive electrode sheet is positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer; or, positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer; or, positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer. This coating form is related to the size of the battery cell and the overall width of the rolling equipment, that is, it satisfies the following rule: if the number of blank foil strips in the middle is x, the number of positive electrode powder strips is x+1, and the number of ceramic glue strips is 2x.

[0020] A preferred solution of this embodiment is that the width of the blank foil area is 5-15 mm.

[0021] The preferred solution of this embodiment is that the width of the positive electrode powder layer: the width L1' / L2' of the middle positive electrode powder layer and the width L1 / L2 of the outermost positive electrode powder layers satisfy the following relationship: L1'=2L1-(0~10)mm / L2'=2L2 The preferred scheme of this embodiment is that the pole piece stripping described in step 4 includes a pole piece structure of a multi-electrode structure battery cell stripping, and the stripping structure includes one-to-two, that is, a side narrow strip area-a side narrow strip area, or, one-to-three, that is, a side narrow strip area-a wide strip area-a side narrow strip area, or, one-to-four, that is, a side narrow strip area-a wide strip area-a side narrow strip area, or, one-to-n, that is, a side narrow strip area-a (n-2) wide strip area-a side narrow strip area, and the cutting line of the slitting knife is on the center line of the blank foil; The electrode structure of the laminated structure battery cell is divided into strips, and the strip structure includes one-to-one, that is, the side narrow strip area-the side narrow strip area is an overall m structure, or one-to-two, that is, a 2m structure, or one-to-three, that is, a 3m structure, or one-to-n, that is, an nm structure, and the cutting line of the cutting knife is on the center line of the middle positive electrode powder, where n is 1, 2, 3...n.

[0022] The preferred solution of this embodiment is that the ceramic glue layer and the positive electrode powder layer are closely arranged side by side or intersecting and overlapping, and the intersection and overlap size is 0.05-1mm.

[0023] A preferred solution of this embodiment is that the width of the ceramic adhesive layer is 1-4 mm.

[0024] The preferred solution of this embodiment is that the thickness of one side of the ceramic glue layer is ≤ the thickness of one side of the positive electrode powder layer; the total thickness of both sides of the ceramic glue layer is ≤ the total thickness of both sides of the positive electrode powder layer.

[0025] A lithium battery cell is a multi-electrode winding cell or a stacked cell made of a positive electrode sheet prepared by a preparation process.

[0026] Figure 1 In the middle, L1'=2L1-(0~10)mm, the number of blank foil strips in the middle is X=2, the number of positive electrode powder strips is x+1=3, and the number of ceramic strips is 2(x+1)=6.

[0027] Figure 2 For an A unit, the number of blank foil strips in the middle is X=1, the number of positive electrode powder strips is x+1=2, and the number of ceramic strips is 2(x+1)=4; Figure 3 The number of blank foil strips in the middle is X=3, the number of positive electrode powder strips is x+1=4, and the number of ceramic strips is 2(x+1)=8; Figure 4 When x=2, the laminated structure is divided into 2 similar A units. Similarly, when x=3, the laminated structure is divided into 3 similar A units, and so on. Figure 5 When x=2, the multi-pole structure is divided into 2 narrow edge strips and 1 wide strip. Similarly, when x=3, the multi-pole structure is divided into 2 narrow edge strips and 2 wide strips, and so on. Figure 6 In the middle, L2'=2L2, the number of blank foil strips in the middle is X=2, the number of positive electrode powder strips is x+1=3, and the number of ceramic strips is 2x=4; Figure 7 For a B unit, the number of blank foil strips in the middle is X=1, the number of positive electrode powder strips is x+1=2, and the number of ceramic strips is 2x=2; Figure 8 The number of blank foil strips in the middle is X=3, the number of positive electrode powder strips is x+1=4, and the number of ceramic strips is 2x=6; Fig. 9 When x=2, the laminated structure is divided into 2 B units. Similarly, when x=3, the laminated structure is divided into 3 B units, and so on. Fig.10 When x=2, the multi-pole ear structure is divided into 2 narrow edge strips and 1 wide strip. Similarly, when x=3, the multi-pole ear is divided into 2 narrow edge strips and 2 wide strips, and so on. Example

[0028] Take the lamination process with ceramic outside as an example See Figure 1 Figure 2 Figure 3 Combination Figure 4 The strips and Fig.11 Film The positive electrode sheet structure of this embodiment includes an aluminum foil substrate 1, a ceramic glue 2, and a positive electrode powder layer 3, wherein the ceramic glue 2 and the positive electrode powder layer are uniformly coated on at least one side of the aluminum foil 1, and the ceramic glue and the positive electrode powder layer are arranged side by side or intersectingly, the non-coated area on the surface of the aluminum foil substrate 1 is blank foil area 1-2, blank foil area 1-3; the ceramic glue layer coated area on the surface of the aluminum foil substrate 1 is ceramic area 2-1, ceramic area 2-2, ceramic area 2-3, and ceramic area 2-4; the positive electrode powder layer coated area on the surface of the aluminum foil 1 is positive electrode powder layer 3-1, positive electrode powder layer 3-2, and positive electrode powder layer 3-3.

[0029] The width of the aluminum foil areas 1-1 and 1-4 on both sides of the pole piece is 0, that is, the blank foils on both sides are cut off before rolling; The positive electrode sheet structure includes an aluminum foil substrate 1, a ceramic glue 2, and a positive electrode powder layer 3, wherein the ceramic glue 2 and the positive electrode powder are evenly coated on at least one side of the aluminum foil 1, and the order from left to right is: positive electrode powder 3-1, ceramic glue 2-1, blank foil area 1-2, ceramic glue 2-2, positive electrode powder 3-2, ceramic glue 2-3, blank foil area 1-3, ceramic glue 2-4, positive electrode powder 3-3.

[0030] Ceramic glue 2-1 and powder 3-1, ceramic glue 2-2, 2-3 and powder 3-2, ceramic glue 2-4 and powder 3-3 are closely connected and distributed side by side; Ceramic glue 2-1 and powder 3-1, ceramic glue 2-2, 2-3 and powder 3-2, ceramic glue 2-4 and powder 3-3 are closely arranged and intersected, and the overlap size is 0-1mm; The width of the ceramic glue 2-1, 2-2, 2-3 and 2-4 is 1-4 mm; The thickness of the ceramic glue 2-1, 2-2, 2-3 and 2-4 on one side is less than or equal to the thickness of the single surface material at 3-1, 3-2 and 3-3.

[0031] The total thickness of the ceramic glue 2-1, 2-2, 2-3 and 2-4 on both sides is less than or equal to the total thickness of the double-sided surface material at 3-1, 3-2 and 3-3.

[0032] The width of the blank foil areas 1-1 and 1-4 is 0-3 mm, which is to prevent the powder from overflowing the edge of the foil during coating. In the existing process, the edge blank foils on both sides of the pole piece are usually used as foil ears, and their width is about 5-20 mm. The wider the width, the higher the risk of breaking the belt during rolling.

[0033] The design idea of ​​the scheme of this embodiment is to transform the existing outer layout foil ear into the inner layout foil ear of the pole piece, and cut off the outer 0-3mm blank foil before rolling, so that the outermost side is the powder line edge. This embodiment can greatly improve the risk of breaking during the foil rolling process and improve the process yield. "Powder line edge" means that the outer 0-3mm blank foil is cut off at the cutting position. Those skilled in the art call the outermost side after cutting the powder line edge. Observe the cut side: the cut cross section has ceramic glue and powder material layers on the upper and lower sides of the foil respectively.

[0034] The manufacturing process of the positive electrode sheet of the multi-electrode winding battery cell includes positive electrode sheet slurry mixing - coating - positive electrode sheet rolling (including cutting edge) - positive electrode sheet primary stripping - laser cutting foil tabs (including secondary stripping); Mixing: Mix the slurry according to the designed slurry ratio and conventional homogenization process; Coating: Prepare the slurry according to Figure 2 Coating is performed according to the pole piece structure and the designed coating amount; Rolling: Preferably, the edge blank foil 1-1 and 1-4 are first cut on the rolling equipment. The structure of the foil before cutting is as follows: Figure 2 The structure of the foil after cutting is as follows Figure 3 , and then roll it according to the designed rolling density.

[0035] Striping: According to the required width of the pole piece, the rolled pole piece is striped, as shown in the figure. Figure 4 , Figure 4The pole piece is divided into three parts, two narrow side strips and a wide middle strip.

[0036] Laser cutting of foil tabs: According to the designed foil tab position and number, the foil tabs are laser cut on the stripped pole piece. The narrow strip pole piece is cut by a single laser. Figure 8 The wide strip pole piece uses dual lasers to cut the pole ears on both sides synchronously. Fig. 9 , the wide strip electrode needs to be divided into two strips, the strip diagram is as follows Fig.10 , after stripping, the pole piece is as follows Fig.11 . Example

[0037] Take the multi-electrode winding process with ceramic outside as an example See attached for details Figure 1 Figure 2 Figure 3 Combination Figure 5 The strips and Figure 12-13 -14-15 laser sectioning The positive electrode sheet structure of the multi-electrode wound battery cell of this embodiment comprises an aluminum foil 1, a ceramic glue 2, and a positive electrode powder 3, wherein the ceramic glue 2 and the positive electrode powder are uniformly coated on at least one side of the aluminum foil 1, and the ceramic glue and the positive electrode powder are arranged side by side or intersectingly, and the non-coated area on the surface of the aluminum foil 1 is blank foil area 1-2, blank foil area 1-3, and blank foil area 1-4; the ceramic glue layer domain on the surface of the aluminum foil substrate 1 is ceramic area 2-1, ceramic area 2-2, ceramic area 2-3, ceramic area 2-4, ceramic area 2-5, and ceramic area 2-6; the positive electrode powder layer domain on the surface of the aluminum foil substrate 1 is powder area 3-1, powder area 3-2, powder area 3-3, and powder area 3-4.

[0038] The width of the blank aluminum foil areas 1-1 and 1-5 on both sides of the electrode is 0, that is, the blank foils on both sides are cut off before rolling; Ceramic glue 2-1 and powder 3-1, ceramic glue 2-2, 2-3 and powder 3-2, ceramic glue 2-4, 2-5 and powder 3-3, ceramic glue 2-6 and powder 3-4 are closely connected and distributed side by side; Ceramic glue 2-1 and powder 3-1, ceramic glue 2-2, 2-3 and powder 3-2, ceramic glue 2-4, 2-5 and powder 3-3, ceramic glue 2-6 and powder 3-4 are closely arranged and intersected, and the overlap size is 0-1mm; The width of the ceramic glue 2-1, 2-2, 2-3, 2-4, 2-5 and 2-6 is 1-4 mm; The thickness of the ceramic glue 2-1, 2-2, 2-3, 2-4, 2-5 and 2-6 on one side is less than or equal to the thickness of the single surface material at 3-1, 3-2, 3-3 and 3-4.

[0039] The total thickness of both sides of the ceramic glue 2-1, 2-2, 2-3, 2-4, 2-5 and 2-6 is less than or equal to the total thickness of the double-sided surface material at 3-1, 3-2, 3-3 and 3-4.

[0040] The width of the blank aluminum foil areas 1-1 and 1-5 is 0-3mm, and its purpose is to prevent the powder from overflowing the edge of the foil during coating. In the existing process, the blank foil on the edges of both sides of the pole piece is usually used as foil ears, and its width is about 5-20mm. The wider the width, the higher the risk of breaking the belt during rolling. The design idea of ​​this embodiment is to transform the existing outer layout foil ears into the inner layout foil ears of the pole piece, and cut off the outer 0-3mm blank foil before rolling, so that the outermost side is the powder line edge. This design can greatly improve the risk of breaking the belt during the foil rolling process and improve the process yield.

[0041] The manufacturing process of the positive electrode sheet of the multi-tab wound battery cell includes positive electrode sheet mixing - coating - positive electrode sheet rolling (including cutting edges) - primary stripping of the positive electrode sheet - laser cutting of the foil tabs (including secondary stripping).

[0042] Mixing: Mix the slurry according to the designed slurry ratio and conventional homogenization process; Coating: Prepare the slurry according to Figure 5 Coating is performed according to the pole piece structure and the designed coating amount; Rolling: Preferably, the edge blank foil material 1-1 and 1-4 are first cut on the rolling equipment. The structure of the foil before cutting is as follows: Figure 5 The structure of the foil after cutting is as follows Figure 6 , and then roll it according to the designed rolling density; Striping: According to the required width of the pole piece, the rolled pole piece is striped. The striping diagram is as follows: Figure 7 , Figure 7 The pole piece is divided into four parts, namely two narrow side strips and two wide middle strips.

[0043] Laser cutting of foil tabs: According to the designed foil tab position and number, the foil tabs are laser cut on the stripped pole piece. The narrow strip pole piece is cut by a single laser. Figure 8 The wide strip pole piece uses dual lasers to cut the pole ears on both sides synchronously. Fig. 9 , the wide strip electrode needs to be divided into two strips, the strip diagram is as follows Fig.10 , after stripping, the pole piece is as follows Fig.11 .

[0044] Laminated battery cell positive electrode sheet prepared using a lithium battery cell positive electrode sheet preparation process Example

[0045] Take the lamination process with the powder line outside as an example See attached for details Figure 6 Figure 7 Figure 8 Combination Fig. 9 Slitting and die cutting The positive electrode sheet structure includes an aluminum foil substrate 1, a ceramic adhesive layer 2, and a positive electrode powder layer 3, and the order from left to right is: blank foil area 1-1, positive electrode powder layer 3-1, ceramic adhesive layer 2-1, blank foil area 1-2, ceramic adhesive layer 2-2, positive electrode powder layer 3-2. When the ceramic adhesive layer 2 and the positive electrode powder layer are evenly coated on both sides of the aluminum foil, the ceramic adhesive layer 2 and the positive electrode powder layer 3 are symmetrically arranged on both sides of the aluminum foil; The width of the blank foil area 1-1 is 0~3mm, and its purpose is to prevent the powder from overflowing the edge of the foil during coating. The width of the blank foil area 1-2 is 5~15mm, and its purpose is to be used as the foil ear of the pole piece. The width of the blank foil in the middle of the pole piece is reduced, thereby reducing the risk of wrinkles during the foil rolling process and improving the process yield. The pole piece is divided into two in the middle of the positive electrode powder layer areas 3-2 and 3-3.

[0046] On the rolling equipment, the blank foil of the incoming electrode is first cut, and then enters the rolling roller for rolling; before rolling, the blank foils 1-1 and 1-4 on both sides of the electrode are cut off. In order to ensure the cutting quality during cutting, the cutter is generally adjusted to the edge of the powder line, and the cutting width is 0-5mm; Sub-clause: According to Fig.13 , when slitting, cut 1 knife into 2 strips, and the pole piece structure slits the pole piece; The pole piece is divided into two in the middle of the positive electrode powder layer areas 3-2 and 3-3.

[0047] Punching: Use a punching die specially designed for pole pieces to punch the pole pieces. Example

[0048] Take the multi-electrode winding process with powder wire outside as an example See attached for details Figure 6 Figure 7 Figure 8 Combination Fig.10 The sub-strips and Figure 12-13 -14-15 laser sectioning The order from left to right is: blank foil area 1-1, positive electrode powder layer 3-1, ceramic glue layer 2-1, blank foil area 1-2, ceramic glue layer 2-2, positive electrode powder layer 3-2.

[0049] Rolling: The width of the blank foil on the edge of the coating is less than 3mm, and no cutting is performed before rolling; Sub-clause: According to Fig.15 (When slitting, cut 2 times to make 3 strips) The pole piece structure is used to slit the pole piece; The pole piece is divided into three parts in the middle of the positive electrode powder layer areas 3-2 and 3-3 and in the middle of the positive electrode powder layer areas 3-4 and 3-5.

[0050] Punching: Use a punching die specially designed for pole pieces to punch the pole pieces.

[0051] The cathode processing technology of this solution avoids the investment in equipment and molds in the early stage of new model development, which can greatly save the development cycle and cost of battery cells. It can greatly improve the development efficiency of models and meet the market demand for fast replacement of consumer products.

[0052] The above-mentioned reference embodiments for the detailed description of the preparation process of the positive electrode sheet of the lithium battery cell and the lithium battery cell are illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should be within the scope of protection of the present invention.

Claims

1. A process for preparing a positive electrode sheet of a lithium battery cell, characterized in that: Specific steps as follows: Step 1, slurry mixing: slurry of the positive electrode powder layer is mixed according to the process requirement ratio; Step 2, coating: using a conventional zebra coating process on one or both sides of the aluminum foil substrate, coating from left to right along the width direction of the aluminum foil substrate, ceramic glue layer-positive electrode powder layer or positive electrode powder layer-ceramic glue layer, to form two positive electrode sheet structures with different coating arrangements; Step 3, rolling: rolling the coated positive electrode sheet; Step 4: Pole sheet stripping: stripping the rolled positive electrode sheet according to the pole sheet width required by the process; Step 5, cutting the foil tabs: according to the position and number of the foil tabs, the foil tabs are cut for the stripped electrode. Laser cutting of foil tabs: For the narrow strip pole piece structure of the multi-pole tab structure battery cell, a single laser is used to cut the foil tabs; for the wide strip pole piece structure, dual lasers are used to simultaneously cut the tabs on both sides, and then the wide strip pole piece is stripped twice to make the positive pole piece; Die punching foil tabs: The foil tabs of laminated structure cells are cut, that is, the stripped pole pieces are punched out with a die-cutting knife to make positive pole pieces.

2. The process for preparing the positive electrode sheet of a lithium battery cell according to claim 1, characterized in that: In step 2, the coating method adopted for the positive electrode sheet structure is: ceramic glue layer-positive electrode powder layer, and the specific structure of the positive electrode sheet is ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer; or, ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer; or, ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer, and this coating form is related to the size of the battery cell and the overall width of the rolling equipment, that is, it satisfies the following rule: the number of blank foil strips in the middle is x, the number of positive electrode powder strips is x+1, and the number of ceramic glue strips is 2(x+1); When the coating method adopted for the positive electrode sheet structure is positive electrode powder layer-ceramic glue layer, the specific structure of the positive electrode sheet is positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer; or, positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer; or, positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer-ceramic glue layer-blank foil area-ceramic glue layer-positive electrode powder layer. This coating form is related to the size of the battery cell and the overall width of the rolling equipment, that is, it satisfies the following rule: if the number of blank foil strips in the middle is x, the number of positive electrode powder strips is x+1, and the number of ceramic glue strips is 2x.

3. The process for preparing the positive electrode sheet of a lithium battery cell according to claim 2, characterized in that: The width of the blank foil area is 5-15 mm.

4. The process for preparing the positive electrode sheet of a lithium battery cell according to claim 2, characterized in that: The width of the positive electrode powder layer: the width L1' / L2' of the middle positive electrode powder layer and the width L1 / L2 of the positive electrode powder layers on the outermost sides satisfy the following relationship: L1'=2L1-(0~10)mm / L2'=2L2.

5. The process for preparing the positive electrode sheet of a lithium battery cell according to claim 1, characterized in that: The pole piece stripping described in step 4 includes a pole piece structure of a multi-electrode structure battery cell stripping, and the stripping structure includes one-to-two, that is, a side narrow strip area-a side narrow strip area, or, one-to-three, that is, a side narrow strip area-a wide strip area-a side narrow strip area, or, one-to-four, that is, a side narrow strip area-a wide strip area-a side narrow strip area, or, one-to-n, that is, a side narrow strip area-a (n-2) wide strip area-a side narrow strip area, and the cutting line of the slitting knife is on the center line of the blank foil; The electrode structure of the laminated structure battery cell is divided into strips, and the strip structure includes one-to-one, that is, the side narrow strip area-the side narrow strip area is an overall m structure, or one-to-two, that is, a 2m structure, or one-to-three, that is, a 3m structure, or one-to-n, that is, an nm structure, and the cutting line of the cutting knife is on the center line of the middle positive electrode powder, and n is the number 1, 2, 3...n.

6. The process for preparing the positive electrode sheet of a lithium battery cell according to claim 1 or 2, characterized in that: The ceramic glue layer and the positive electrode powder layer are closely arranged side by side or intersecting and overlapping, and the intersection and overlap size is 0.05-1mm.

7. The process for preparing the positive electrode sheet of a lithium battery cell according to claim 1 or 2, characterized in that: The width of the ceramic adhesive layer is 1-4 mm.

8. The process for preparing the positive electrode sheet of a lithium battery cell according to claim 1 or 2, characterized in that: The thickness of one side of the ceramic glue layer is less than or equal to the thickness of one side of the positive electrode powder layer; the total thickness of both sides of the ceramic glue layer is less than or equal to the total thickness of both sides of the positive electrode powder layer.

9. A lithium battery cell, characterized in that: A multi-electrode wound battery cell or a laminated battery cell made of a positive electrode sheet prepared by any one of the preparation processes of claims 1-8.

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