Positive plate, preparation method thereof and battery

Abstract

The invention belongs to the technical field of battery manufacturing, and particularly relates to a positive plate and a preparation method thereof and a battery, the positive plate comprises a current collector and an active material layer on the current collector, the current collector is welded with a positive tab, the positive tab, the current collector and the active material layer form a pole piece layer, and a plurality of gummed paper layers are arranged on the pole piece layer. The position where the gummed paper layer is attached to the pole piece layer is a bonding area, the bonding area is provided with an isolating layer, and the isolating layer is arranged below the gummed paper layer. According to the invention, the nano ceramic material is sprayed at the adhesive sticking position by using an electrostatic spraying method, and then the adhesive paper sticking process is carried out, so that a thin electronic insulation isolation layer is formed between the adhesive paper layer and the positive plate layer, and the oxidation-reduction reaction of the positive electrode in a high-voltage state on the adhesive paper layer is blocked; the blackening, expansion and stripping phenomena of the positive electrode adhesive paper under high-temperature and high-voltage working conditions are eliminated, so that the cycle performance and thickness expansion of the battery are improved, and the safety performance of the battery under the high-temperature working condition is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery manufacturing, and in particular relates to a positive electrode sheet and a preparation method thereof, and a battery. Background Art

[0002] At present, lithium-ion batteries are widely used in the consumer electronics industry as portable energy storage devices. With the pursuit of high energy density of batteries by manufacturers and consumers, the upper limit of charging voltage of 3C consumer batteries has been continuously increased, and has now reached a voltage upper limit of 4.6V. In the preparation process of consumer batteries, one of the processes is to apply adhesive tape on the positive electrode sheet to protect the welded positive ear and prevent lithium deposition at the negative electrode position corresponding to the adhesive tape. The adhesive tape positions on the positive electrode sheet are divided into four types: positive ear tape, negative ear protection tape, positive head tape, and positive tail tape.

[0003] However, when the battery is working under high temperature (>35℃) and high voltage (>4.48V), the adhesive layer of the positive electrode ear tape will produce a violent redox reaction, causing the positive electrode ear tape to turn black, the thickness of the tape to swell, and even the tape to peel off the positive electrode and lose its protective function. This will deteriorate the performance of the battery, cause the battery thickness to expand, and cause lithium deposition at the negative electrode and other safety hazards. Summary of the invention

[0004] The purpose of the present invention is to provide a positive electrode sheet and a preparation method thereof and a battery in view of the deficiencies in the prior art. The positive electrode sheet is coated with a layer of nano-ceramic material at the gluing position thereof by an electrostatic spraying method, and then a tape-applying process is performed to form a thin electronic insulating isolation layer between the tape layer and the electrode layer, thereby blocking the oxidation-reduction reaction of the positive electrode in a high voltage state on the tape layer.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A positive electrode sheet comprises a current collector and an active material layer thereon, wherein the current collector is welded with a positive electrode ear, and the positive electrode ear, the current collector and the active material layer constitute a pole sheet layer, and a plurality of adhesive paper layers are arranged on the pole sheet layer, and the position where the adhesive paper layer and the pole sheet layer are in contact is a bonding area, and the bonding area is provided with an isolation layer, and the isolation layer is arranged below the adhesive paper layer.

[0007] Preferably, the isolation layer is a nano-ceramic material, including any one or a combination of two or more of alumina, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

[0008] Preferably, the particle size dv50 of the nano-ceramic material is 10nm-10μm, and the thickness of the isolation layer is 0.1-10μm. Specifically, the particle size dv50 of the nano-ceramic material is 10nm, 20nm, 50nm, 100nm, 200nm, 500nm, 1μm, 2μm, 5μm and 10μm. Specifically, the thickness of the isolation layer is 0.1μm, 0.2μm, 0.5μm, 0.8μm, 1μm, 3μm, 5μm, 7μm and 10μm.

[0009] Preferably, the adhesive tape layer includes positive electrode ear adhesive tape, negative electrode ear protective adhesive tape, positive electrode head adhesive tape and positive electrode tail adhesive tape. The positive electrode ear adhesive tape is attached to the top of the positive electrode ear, the negative electrode ear protective adhesive tape is attached to the negative electrode ear position of the negative electrode sheet corresponding to the positive electrode sheet to play a protective role, the positive electrode head adhesive tape is attached to the starting end of the positive electrode sheet, and the positive electrode tail adhesive tape is attached to the ending end of the positive electrode sheet.

[0010] Preferably, the active material layer is provided with a tab area on the current collector, the positive tab is provided in the tab area, the tab area is surrounded by a bonding area, and the positive tab tape is adhered and covered on the tab area to protect the positive tab in the tab area.

[0011] Preferably, the active material layer is provided on both sides of the current collector in the thickness direction, an even number of the tab regions are provided in the active material layer and are opposite to each other, and the positive tab is provided in at least one of the tab regions. In some embodiments, a positive tab is provided in only a single tab region on one side, and in other embodiments, a positive tab is provided in each of the opposite tab regions on both sides and welded together.

[0012] Preferably, at least one negative electrode ear protection tape is disposed on each of the active material layers on both sides, and the negative electrode ear protection tapes disposed on both sides are staggered. In some embodiments, the negative electrode ear protection tapes are arranged on the active material layer in this regular pattern, so as to protect the corresponding negative electrode ear on the negative electrode sheet after the positive electrode sheet and the negative electrode sheet are wound into a battery cell.

[0013] Preferably, the area of ​​the isolation layer is greater than or equal to the area of ​​the adhesive paper layer, so as to completely separate the adhesive paper layer from the electrode layer, thereby isolating the oxidation-reduction reaction of the positive electrode in a high-voltage state on the adhesive paper layer, and eliminating the blackening, expansion and peeling of the positive electrode adhesive paper under high temperature and high voltage working conditions.

[0014] A method for preparing the above-mentioned positive electrode sheet comprises the following steps:

[0015] Step 1, lithium cobalt oxide, binder PVDF, conductive agent SP and CNT are mixed and dissolved in NMP and stirred to obtain a positive electrode active material layer slurry, which is coated on a current collector and dried, and then the positive electrode ear is welded on the ear area by roller pressing to obtain a positive electrode sheet semi-finished product;

[0016] Step 2: using an electrostatic spraying device to spray the nano ceramic material on the bonding area of ​​the pole piece layer to form an isolation layer;

[0017] Step 3: After the electrostatically sprayed nano-ceramic material is shaped, the corresponding positive electrode ear tape, negative electrode ear protection tape, positive electrode head tape and positive electrode tail tape are pasted on the isolation layer.

[0018] A battery comprises any one of the positive electrode sheets described above.

[0019] Compared with the prior art, the beneficial effect of the present invention is that: a positive electrode sheet provided by the present invention is sprayed with nano-ceramic material at the gluing position by an electrostatic spraying method, and then a tape-applying process is performed to form a thin electronic insulating isolation layer between the tape layer and the positive electrode sheet layer, thereby blocking the oxidation-reduction reaction of the positive electrode in a high-voltage state on the tape layer, and eliminating the blackening, expansion and peeling of the positive electrode tape under high-temperature and high-voltage working conditions, thereby improving the cycle performance and thickness expansion of the battery, and improving the safety performance of the battery under high-temperature conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front structural schematic diagram of an embodiment of the present invention.

[0021] Figure 2 It is a schematic diagram of the reverse structure of an embodiment of the present invention.

[0022] Figure 3 It is a schematic diagram of the side structure of an embodiment of the present invention.

[0023] Figure 4 It is a schematic diagram of the local structure of an embodiment of the present invention.

[0024] Reference numerals:

[0025] 10. Pole sheet layer, 11. Current collector, 12. Active material layer, 13. Positive electrode ear, 14. Isolation layer;

[0026] 15. Adhesive tape layer, 151. Positive ear adhesive tape, 152. Negative ear protective adhesive tape, 153. Positive head adhesive tape, 154. Positive tail adhesive tape;

[0027] 101. bonding area, 102. tab area. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] .Example 1:

[0030] like Figure 1-4 As shown, the positive electrode sheet is prepared by the following steps:

[0031] Step 1, lithium cobalt oxide, binder PVDF, conductive agent SP and CNT are mixed in a mass ratio of 97:2:0.5:0.5, dissolved in NMP, and stirred to obtain a positive electrode active material layer 12 slurry, which is coated on the current collector 11 and dried, and then rolled and welded to the positive electrode ear 13 on the ear area 102 to obtain a positive electrode sheet semi-finished product;

[0032] Step 2: Use an electrostatic spraying device to spray a boehmite ceramic material with a particle size of 10 nm on each bonding area 101 of the pole piece layer 10 to form an isolation layer 14, and the spraying thickness of the isolation layer 14 is controlled to be 0.5 μm;

[0033] Step 3: After the electrostatically sprayed boehmite ceramic material is shaped, the corresponding positive electrode ear tape 151, negative electrode ear protection tape 152, positive electrode head tape 153 and positive electrode tail tape 154 are pasted on each isolation layer 14.

[0034] Embodiment 2:

[0035] Example 2 is carried out with reference to Example 1, except that in step 2, the spraying thickness of the isolation layer 14 is controlled to be 0.1 μm.

[0036] Embodiment 3:

[0037] Example 3 is carried out with reference to Example 1, except that the spraying thickness of the isolation layer 14 in step 2 is controlled to be 1 μm.

[0038] Embodiment 4:

[0039] Example 4 is carried out with reference to Example 1, except that the spraying thickness of the isolation layer 14 in step 2 is controlled to be 2 μm.

[0040] Embodiment 5:

[0041] Example 5 is carried out with reference to Example 1, except that the spraying thickness of the isolation layer 14 in step 2 is controlled to be 3 μm.

[0042] Embodiment 6:

[0043] Example 6 is carried out with reference to Example 1, except that the particle size of the boehmite ceramic material used in step 2 is 20 nm.

[0044] Embodiment 7:

[0045] Example 7 is carried out with reference to Example 1, except that the particle size of the boehmite ceramic material used in step 2 is 30 nm.

[0046] Embodiment 8:

[0047] Example 8 is carried out with reference to Example 1, except that the particle size of the boehmite ceramic material used in step 2 is 50 nm.

[0048] Embodiment 9:

[0049] Example 9 is carried out with reference to Example 1, except that the nano ceramic material used in step 2 is a titanium dioxide ceramic material with a particle size of 10 nm.

[0050] Embodiment 10:

[0051] Example 10 is carried out with reference to Example 1, except that the nano ceramic material used in step 2 is a barium sulfate ceramic material with a particle size of 10 nm.

[0052] Comparative Example 1:

[0053] The positive electrode sheet was prepared by the following steps:

[0054] Step 1, lithium cobalt oxide, binder PVDF, conductive agent SP and CNT are mixed in a mass ratio of 97:2:0.5:0.5, dissolved in NMP, and stirred to obtain a positive electrode active material layer 12 slurry, which is coated on the current collector 11 and dried, and then rolled and welded to the positive electrode ear 13 on the ear area 102 to obtain a positive electrode sheet semi-finished product;

[0055] Step 2: Paste the corresponding positive electrode ear tape 151, negative electrode ear protection tape 152, positive electrode head tape 153 and positive electrode tail tape 154 on the positive electrode semi-finished product.

[0056] Battery preparation: Graphite, aqueous binder, CNT and SP are stirred and mixed with a solvent in a mass ratio of 97:2:0.5:0.5, and then the slurry is coated on a copper foil and dried, and the negative electrode sheet is obtained by rolling and slitting.

[0057] The positive electrode sheets, negative electrode sheets, separators and electrolytes of the above embodiments and comparative examples were made into soft-pack batteries, and performance tests were performed after the batteries were divided into different capacities. The test results are recorded in Table 1 below.

[0058] Table 1:

[0059]

[0060]

[0061] As shown in Table 1, it can be seen from Examples 1-10 and Comparative Example 1 that adding an isolation layer 14 between the pole layer 10 and the adhesive paper layer 15 can effectively isolate the blackening, expansion and peeling of the adhesive paper layer 15 of the positive electrode under high voltage conditions, thereby improving the cycle performance and thickness expansion of the battery, and improving the safety performance of the battery under high temperature conditions.

[0062] As shown in Table 1, it can be seen from Examples 1-5 that when a boehmite ceramic material with a particle size of 10 nm is used as the isolation layer 14, when the coating thickness of the isolation layer 14 is less than 0.5 μm, the cycle performance of the battery decreases and the thickness expansion rate increases, and when the coating thickness of the isolation layer 14 is greater than 0.5 μm, the cycle performance of the battery decreases and the thickness expansion rate increases. Therefore, it can be seen that the battery performance is optimal when the coating thickness is 0.5 μm.

[0063] As shown in Table 1, it can be seen from Examples 1, 6-8 that when the particle size of the boehmite ceramic material gradually increases, the cycle performance of the battery decreases and the thickness expansion rate increases. Therefore, within the applicable range, the battery performance obtained when a ceramic material with a smaller particle size is used is better.

[0064] As shown in Table 1, it can be seen from Examples 1, 9, and 10 that when the various nano-ceramic materials proposed in the present application are used as the isolation layer 14, relatively excellent battery performance effects can be achieved.

[0065] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A positive electrode sheet, comprising a current collector (11) and an active material layer (12) thereon, characterized in that: The current collector (11) is welded with a positive electrode ear (13), and the positive electrode ear (13), the current collector (11) and the active material layer (12) constitute a pole piece layer (10). The pole piece layer (10) is provided with a plurality of adhesive paper layers (15), and the position where the adhesive paper layers (15) and the pole piece layer (10) are in contact is a bonding area (101). The bonding area (101) is provided with an isolation layer (14), and the isolation layer (14) is arranged below the adhesive paper layer (15).

2. The positive electrode sheet according to claim 1, characterized in that: The isolation layer (14) is a nano-ceramic material, including any one or a combination of two or more of alumina, boehmite, barium sulfate, silicon dioxide, magnesium oxide, silicon nitride, boron nitride, aluminum nitride, silicon carbide, zirconium oxide, and titanium dioxide.

3. The positive electrode sheet according to claim 2, characterized in that: The particle size dv50 of the nano ceramic material is 10 nm-10 μm, and the thickness of the isolation layer (14) is 0.1-10 μm.

4. The positive electrode sheet according to claim 1, characterized in that: The adhesive tape layer (15) includes positive electrode ear adhesive tape (151), negative electrode ear protection adhesive tape (152), positive electrode head adhesive tape (153) and positive electrode tail adhesive tape (154).

5. The positive electrode sheet according to claim 4, characterized in that: The active material layer (12) is provided with a tab area (102) on the current collector (11); the positive tab (13) is provided in the tab area (102); the tab area (102) is surrounded by a bonding area (101); and the positive tab adhesive tape (151) is bonded and covered on the tab area (102).

6. The positive electrode sheet according to claim 5, characterized in that: The active material layer (12) is provided on both sides of the current collector (11) in the thickness direction, an even number of oppositely positioned pole lug regions (102) are provided in the active material layer (12), and the positive pole lug (13) is provided in at least one of the pole lug regions (102).

7. The positive electrode sheet according to claim 6, characterized in that: At least one negative electrode tab protective adhesive tape (152) is disposed on each of the active material layers (12) on both sides, and the negative electrode tab protective adhesive tapes (152) disposed on both sides are staggered.

8. The positive electrode sheet according to claim 1, characterized in that: The area of ​​the isolation layer (14) is greater than or equal to the area of ​​the adhesive paper layer (15).

9. A method for preparing a positive electrode sheet according to any one of claims 1 to 8, characterized in that: The steps include: Step 1: lithium cobalt oxide, binder PVDF, conductive agent SP and CNT are mixed and dissolved in NMP and stirred to obtain a positive electrode active material layer (12) slurry, which is coated on a current collector (11) and dried, and then rolled and welded to a positive electrode ear (13) on an electrode ear region (102) to obtain a positive electrode sheet semi-finished product; Step 2: using an electrostatic spraying device to spray the nano ceramic material onto the bonding area (101) of the pole piece layer (10) to form an isolation layer (14); Step 3: After the electrostatically sprayed nano-ceramic material is shaped, the corresponding positive electrode ear tape (151), negative electrode ear protection tape (152), positive electrode head tape (153) and positive electrode tail tape (154) are pasted on the isolation layer (14).

10. A battery, characterized in that: It includes the positive electrode sheet according to any one of claims 1 to 8 or the positive electrode sheet prepared by the positive electrode sheet preparation method according to claim 9.

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