Electrode plate, preparation method thereof and lithium ion battery

Abstract

The invention relates to an electrode plate, a preparation method thereof and a lithium ion battery. The preparation method of the electrode plate comprises the following steps that S1, the electrode plate is prepared, the electrode plate comprises a current collector and an active layer arranged on the surface of the current collector, and the active layer comprises a binder; s2, performing plasma cleaning on the active layer by using oxidizing gas; and the infiltration angle of the electrode plate to the electrolyte is 5-30 degrees. The surface of the electrode active layer is subjected to plasma cleaning, so that the infiltration angle between the electrolyte and the surface of the electrode can be effectively reduced, the infiltration performance of the electrode is improved, and the infiltration time of the battery is shortened.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to an electrode plate and a preparation method thereof, and a lithium-ion battery. Background Art

[0002] In batteries, the electrolyte plays the role of transmitting lithium ions. The electrolyte realizes the transfer of lithium ions from the electrodes to the electrolyte by soaking the electrodes. Therefore, the wettability of the electrolyte and the electrodes is very important for the performance of the battery. If the electrolyte has poor wettability to the electrodes, it will lead to increased internal resistance of the battery, reduced capacity, unstable electrolyte interface film, and affect the battery life. At the same time, the poor wettability of the electrolyte will also affect the high and low temperature performance and cycle life of the battery. In existing production, due to the slow wettability of the electrodes and the electrolyte, in order to achieve good electrolyte infiltration, the battery cell often needs to be left standing for a long time, and the production efficiency is low. Therefore, there is an urgent need for an electrode plate that can achieve a good wettability with the electrolyte in a short time. Summary of the Invention

[0003] Based on this, the present application provides an electrode plate and a preparation method thereof, and a lithium-ion battery to solve the above technical problems.

[0004] A first aspect of the present application provides a method for preparing a battery electrode, comprising the following steps:

[0005] S1. Prepare an electrode plate, wherein the electrode plate includes a current collector and an active layer disposed on a surface of the current collector, and the active layer includes a binder;

[0006] S2. Plasma cleaning the active layer using an oxidizing gas;

[0007] The wetting angle of the electrode plate to the electrolyte is 5°~30°.

[0008] In the present application, by plasma cleaning the surface of the electrode active layer, the wetting angle between the electrolyte and the electrode surface can be effectively reduced, the wetting performance of the electrode can be improved, and the wetting time of the battery can be shortened.

[0009] In some embodiments, step S2 comprises the following steps:

[0010] S21, transferring the electrode plate to the plasma cleaning station;

[0011] S22, ionizing the oxidizing gas into plasma;

[0012] S23. Spray the plasma uniformly onto the surface of the active layer.

[0013] In some embodiments, the gas pressure is 0.1 MPa to 0.5 MPa.

[0014] In some embodiments, the plasma cleaning time is 0.1s to 300s.

[0015] In some embodiments, the power of plasma cleaning is 100W-1000W.

[0016] In some embodiments, the temperature of plasma cleaning is 10°C to 45°C.

[0017] In some embodiments, the plasma cleaning distance is 2 cm to 10 cm.

[0018] In some embodiments, the gas includes at least one of O2, F2, Cl2, and NO2.

[0019] The second aspect of the present application provides an electrode plate, which is manufactured using the preparation method provided by the first aspect above.

[0020] A third aspect of the present application provides a lithium-ion battery, which includes the electrode plate provided in the second aspect.

[0021] This application adds a binder to the active layer of the electrode plate and uses an oxidizing gas to plasma clean the active layer. On the one hand, the high-energy plasma acting on the surface of the electrode plate will cause the chemical bonds of the binder to break. The free radicals in the plasma can form polar groups with the broken covalent bonds, increasing the proportion of polar groups on the surface of the electrode layer and thus improving the electrode's wetting performance. On the other hand, the gas source contains an oxidizing gas that can react with the binder to generate hydroxyl groups, carboxyl groups, and other active groups that are conducive to the infiltration of electrolyte groups, thereby improving the interfacial infiltration of the electrolyte and the electrode, and achieving an infiltration angle of 5° to 30° for the electrode plate to the electrolyte in a short period of time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a process flow chart of a method for preparing an electrode plate in one embodiment of the present application.

[0023] Figure 2 This is a photo of the positive electrode plate in Example 1 of the present application after 6 hours of immersion. DETAILED DESCRIPTION

[0024] Reference will now be made to embodiments of the present application in detail, one or more examples of which are described below. Each example is provided to illustrate, but not to limit, the present application. Indeed, it will be apparent to those skilled in the art that various modifications and variations may be made to the present application without departing from the scope or spirit of the present application. For example, features illustrated or described as part of one embodiment may be used in another embodiment to produce further embodiments.

[0025] Therefore, it is intended that this application covers such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features, and aspects of the present application are disclosed in or are apparent from the following detailed description. Those skilled in the art will appreciate that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.

[0026] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0027] In this application, when referring to numerical ranges, unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges subsumed therein.

[0028] In this document, when referring to a range, if the unit is followed only by the right endpoint, it means that the units of the left and right endpoints are the same. For example, 100~150 nm means that the units of the left endpoint "100" and the right endpoint "150" are both nm (nanometers).

[0029] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0030] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0031] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, "the method includes steps (a) and (b)" means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, "the method may further include step (c)" means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0032] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0033] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0034] like Figure 1 As shown, the first aspect of the present application provides a method for preparing a battery electrode, comprising the following steps:

[0035] S1. Prepare an electrode plate, wherein the electrode plate includes a current collector and an active layer disposed on a surface of the current collector, and the active layer includes a binder;

[0036] S2. Plasma cleaning the active layer using an oxidizing gas.

[0037] In the present application, by plasma cleaning the surface of the electrode active layer, the wetting angle between the electrolyte and the electrode surface can be effectively reduced, the wetting performance of the electrode can be improved, and the wetting time of the battery can be shortened.

[0038] It is understandable that the above-mentioned electrode plates refer to positive electrode plates and / or negative electrode plates.

[0039] In some embodiments, the electrode plate is a positive electrode plate, the current collector is an aluminum foil, and the active layer includes a positive electrode active material, a positive electrode binder, and a positive electrode conductor.

[0040] The positive electrode active material includes at least one of lithium manganese oxide, lithium manganese iron phosphate, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide and manganese-rich lithium-based positive electrode materials.

[0041] The positive electrode binder includes but is not limited to one or more of polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, and lithium alginate.

[0042] Positive electrode conductive agents include carbon black, graphite, super-P, acetylene black (such as KETCHEN™ black or DENKA™ black), carbon fibers and nanotubes, graphene, and the like.

[0043] In some embodiments, the electrode plate is a negative electrode plate, the current collector is a copper foil, and the active layer includes a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent.

[0044] The negative electrode active material includes, but is not limited to, one or more of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, lithium titanate (Li2TiO3) and tin-based materials.

[0045] The negative electrode binder includes, but is not limited to, one or more of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride hexafluoropropylene, polypropylene, polyethylene, and polyimide.

[0046] The negative electrode conductive agent includes, but is not limited to, one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, carbon nanofibers, and graphene.

[0047] It can be understood that the above-mentioned materials for positive electrode active material, positive electrode conductor, positive electrode binder, negative electrode active material, negative electrode conductor and negative electrode binder are merely illustrative examples. Without violating the inventive concept of this application, any known positive electrode active material, positive electrode conductor, positive electrode binder, negative electrode active material, negative electrode conductor and negative electrode binder can be used in this application.

[0048] In some embodiments, during the plasma cleaning process, the gas pressure is 0.1 MPa to 0.5 MPa, including but not limited to 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, and 0.5 MPa.

[0049] In some embodiments, the electrode sheet prepared by the above preparation method has a wetting angle of 5° to 30° with respect to the electrolyte.

[0050] It is understandable that, in the present application, there is no particular limitation on the process for preparing the electrode plates in the above step S1. Without violating the inventive concept of the present application, any known process for preparing the electrode plates can be used in the present application.

[0051] Exemplarily, step S1 prepares a positive electrode sheet, which specifically includes the following steps:

[0052] S11, mixing the positive electrode active material, the positive electrode conductive agent, and the positive electrode binder by jet milling, adding a solvent to prepare a slurry;

[0053] S12. Coating the slurry on the surface of the aluminum foil current collector to form an active layer on the surface of the aluminum foil current collector.

[0054] Exemplarily, step S1 prepares a negative electrode sheet, which specifically includes the following steps:

[0055] S11, mixing the negative electrode active material, the negative electrode conductive agent, and the negative electrode binder by jet milling, adding a solvent to prepare a slurry;

[0056] S12. Coating the slurry on the surface of the copper foil current collector to form an active layer on the surface of the copper foil current collector.

[0057] In some embodiments, in step S11 , coating is performed by dry spraying or electrostatic spraying.

[0058] In some embodiments, step S2 includes the following steps:

[0059] S21, transferring the electrode plate to the plasma cleaning station;

[0060] S22, ionizing the oxidizing gas into plasma;

[0061] S23, spraying the plasma evenly onto the surface of the active layer to complete plasma cleaning.

[0062] In some embodiments, the plasma cleaning time is 0.1s to 300s, including but not limited to 0.1s, 10s, 30s, 45s, 60s, 80s, 100s, 150s, 200s, 250s, and 300s. Preferably, the plasma cleaning time is 1s to 60s.

[0063] In some embodiments, the power of plasma cleaning is 100W~1000W, including but not limited to 100W, 200W, 300W, 400W, 500W, 600W, 700W, 900W, 1200W, 1400W, 1600W, 1800W, and 2000W.

[0064] In some embodiments, the temperature of plasma cleaning is 10°C to 45°C, including but not limited to 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, and 45°C.

[0065] In some embodiments, the plasma cleaning distance is 2 cm to 10 cm, including but not limited to 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, and 10 cm.

[0066] In some embodiments, the gas includes at least one of O2, F2, Cl2, and NO2.

[0067] In some embodiments, the gas is pure O2.

[0068] In some embodiments, the time it takes for the electrolyte to wet the surface of the electrode piece after plasma cleaning is reduced by 20% to 50% compared to the electrode piece after non-plasma cleaning.

[0069] This application adds a binder to the active layer of the electrode plate and uses an oxidizing gas to plasma clean the active layer. On the one hand, when the high-energy plasma acts on the surface of the electrode plate, it will cause the chemical bonds of the binder to break. The free radicals in the plasma can form polar groups with the broken covalent bonds, increasing the proportion of polar groups on the surface of the electrode layer, thereby improving the wettability of the electrode.

[0070] At the same time, high-energy plasma can act on the surface of the electrode plate, thereby cleaning away inert groups on the surface of the electrode plate that are not conducive to wetting, and high-energy particles produce a certain etching effect on the surface of the active material particles, increasing the specific surface area of ​​the active material particles, thereby improving the wetting performance of the electrode plate.

[0071] On the other hand, the gas in the gas source has an oxidizing effect, which can react with the binder to generate active groups such as hydroxyl and carboxyl groups that are beneficial to the infiltration of electrolyte groups, thereby improving the interface wetting between the electrolyte and the electrode, so that the wetting angle of the electrode plate to the electrolyte can reach 5°~30° in a shorter time.

[0072] The second aspect of the present application provides an electrode plate, which is manufactured using the preparation method provided by the first aspect above.

[0073] A third aspect of the present application provides a lithium-ion battery, which includes the electrode plate provided in the second aspect.

[0074] It is understood that the lithium-ion battery further includes a separator and an electrolyte disposed between the positive electrode sheet and the negative electrode sheet, wherein at least one of the positive electrode sheet and the negative electrode sheet is subjected to a plasma cleaning process.

[0075] A fourth aspect of the present application provides a method for preparing a lithium ion battery, comprising the following steps:

[0076] The positive electrode sheet and / or the negative electrode sheet are prepared using the preparation method provided in the first aspect above.

[0077] The surface of the prepared positive electrode sheet and / or negative electrode sheet is subjected to plasma cleaning treatment.

[0078] Assemble the positive electrode sheet, separator and negative electrode sheet.

[0079] The electrolyte is injected to produce a lithium-ion battery.

[0080] The present application will be further described below with reference to specific embodiments and comparative examples.

[0081] Example 1

[0082] The positive electrode active material lithium manganese oxide, the binder PVDF, and the conductive agent Super-P were weighed in a mass ratio of 95:3:2, and mixed evenly by air jet milling. The solvent NMP was added to form a uniform slurry. The slurry was coated on the surface of the positive electrode current collector aluminum foil, dried, and pressed to form a positive electrode sheet. The positive electrode sheet includes an aluminum foil current collector and an active layer arranged on the surface of the aluminum foil current collector.

[0083] Plasma cleaning is performed on the surface of the active layer away from the current collector: the positive electrode plate is transferred to the plasma cleaning station, the gas source is ionized to form plasma, and the plasma is evenly sprayed onto the surface of the positive electrode plate to complete the plasma cleaning.

[0084] Among them, the gas source is O2; the gas pressure is 0.3 MPa; the gas flow rate is 1.8 L / min; the plasma cleaning time is 10 s; the plasma cleaning power is 400 W; the operating temperature in the cavity of the plasma cleaning equipment is 25 ° C; and the plasma cleaning treatment distance is 8 cm.

[0085] The negative electrode active material graphite, binder PVDF, and conductive agent Super-P were weighed in a mass ratio of 95:3:2 and mixed evenly by air jet milling. The solvent NMP was added to form a uniform slurry. The slurry was coated on the surface of the positive electrode current collector copper foil, dried, and pressed to form a negative electrode sheet. The negative electrode sheet includes a copper foil current collector and an active layer arranged on the surface of the copper foil current collector.

[0086] Plasma cleaning is performed on the surface of the active layer away from the current collector: the negative electrode plate is transferred to the plasma cleaning station, the gas source is ionized to form plasma, and the plasma is evenly sprayed onto the surface of the negative electrode plate to complete the plasma cleaning.

[0087] Among them, the gas source is O2; the gas pressure is 0.3 MPa; the gas flow rate is 1.8 L / min; the plasma cleaning time is 10 s; the plasma cleaning power is 400 W; the operating temperature in the cavity of the plasma cleaning equipment is 25°C; and the plasma cleaning treatment distance is 8 cm.

[0088] The positive electrode sheet, negative electrode sheet and separator after the above plasma cleaning treatment are assembled. The separator is a PP / PE composite separator. They are stacked in the order of positive electrode / separator / negative electrode / separator / positive electrode and placed in an aluminum-plastic film to produce a semi-encapsulated battery.

[0089] Injecting electrolyte to form a battery: injecting electrolyte into the semi-encapsulated battery prepared above, the composition of the electrolyte is: diethyl carbonate DEC, ethylene carbonate EC, propylene carbonate PC, fluoroethylene carbonate FEC, lithium hexafluorophosphate LiPF6, and lithium difluorooxalatoborate LiDFOB are weighed and mixed in a mass ratio of 56:14:9:6:14:1.

[0090] like Figure 2 As shown, this is a photo of the positive electrode sheet prepared in this embodiment after 6 hours of infiltration. There are no black spots or lithium precipitation, and the infiltration is good.

[0091] Example 2

[0092] The difference between Example 2 and Example 1 is that the gas pressure of plasma cleaning is 0.1 MPa.

[0093] Example 3

[0094] The difference between Example 3 and Example 1 is that the gas pressure of plasma cleaning is 0.5 MPa.

[0095] Example 4

[0096] The difference between Example 4 and Example 1 is that the plasma cleaning time is 0.1 s.

[0097] Example 5

[0098] The difference between Example 5 and Example 1 is that the plasma cleaning time is 300 s.

[0099] Example 6

[0100] The difference between Example 6 and Example 1 is that the power of plasma cleaning is 100 W.

[0101] Example 7

[0102] The difference between Example 7 and Example 1 is that the power of plasma cleaning is 1000 W.

[0103] Example 8

[0104] The difference between Example 8 and Example 1 is that the gas source composition is NO2:O2=20%:80%.

[0105] Comparative Example 1

[0106] The difference between this comparative example and Example 1 is that the electrode plates are not plasma cleaned.

[0107] Comparative Example 2

[0108] The difference between this comparative example and Example 1 is that the gas source is compressed air.

[0109] Comparative Example 3

[0110] The difference between this comparative example and Example 1 is that the gas source adopts inert gas argon.

[0111] Test Case

[0112] Place the electrode of the test sample on the sample stage of the contact angle tester, draw the electrolyte into the test needle, adjust the needle to be placed vertically to the test sample, drop 50uL onto the sample surface, test the contact angle 5 times and take the average value.

[0113] The relevant parameters and test results of the embodiments and comparative examples are summarized in Table 1 below:

[0114]

[0115] As can be seen from the above table, plasma cleaning of the electrode with oxidizing gas can effectively improve the contact between the electrolyte and the electrode and reduce the electrolyte infiltration time.

[0116] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing a battery electrode, characterized in that: The following steps are involved: S1. preparing an electrode plate, wherein the electrode plate comprises a current collector and an active layer disposed on a surface of the current collector, and the active layer comprises a binder; S2, plasma cleaning the active layer using an oxidizing gas; The wetting angle of the electrode plate to the electrolyte is 5°~30°.

2. The method for preparing a battery pole piece according to claim 1, characterized in that: Step S2 includes the following steps: S21, transferring the electrode plate to a plasma cleaning station; S22, ionizing the oxidizing gas into plasma; S23, spraying the plasma uniformly onto the surface of the active layer.

3. The method for preparing a battery pole piece according to claim 1, characterized in that: The gas pressure is 0.1MPa~0.5MPa.

4. The method for preparing a battery pole piece according to claim 1, characterized in that: The plasma cleaning time is 0.1s~300s.

5. The method for preparing a battery pole piece according to claim 1, characterized in that: The power of the plasma cleaning is 100W~1000W.

6. The method for preparing a battery pole piece according to claim 1, characterized in that: The temperature of the plasma cleaning is 10°C to 45°C.

7. The method for preparing a battery pole piece according to claim 1, characterized in that: The distance of the plasma cleaning is 2 cm to 10 cm.

8. The method for preparing a battery pole piece according to claim 1, characterized in that: The gas includes at least one of O2, F2, Cl2, and NO2.

9. An electrode plate, characterized in that: The electrode plate is prepared by the preparation method described in any one of claims 1 to 8.

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the electrode sheet of claim 9.

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