Negative pole piece and preparation method thereof, battery and electric equipment

Abstract

The invention discloses a negative pole piece and a preparation method thereof, a battery and electric equipment, the negative pole piece comprises a current collector, at least one side surface of the current collector in the thickness direction is provided with a main body area and a margin area, and the margin area is located at the periphery of the main body area; wherein the main body region is provided with a negative electrode active material layer, the residual region is provided with a diffusion inhibition layer, and the diffusion inhibition layer comprises a first negative electrode active material and an insulating material. According to the negative pole piece disclosed by the invention, the diffusion inhibition layer in the remaining area is arranged to be the mixture comprising the first negative active material and the insulating material, so that the diffusion inhibition layer can receive embedded lithium ions and can inhibit the diffusion of the lithium ions to a certain extent, and thus the problem of lithium precipitation at the edge of the negative pole piece can be effectively relieved; and the cycle index and the service life of the lithium ion battery can be prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and in particular relates to a negative electrode plate and a preparation method thereof, a battery and an electrical device. Background Art

[0002] During the charge and discharge process of lithium-ion batteries, lithium ions escape from the positive electrode. If the negative electrode does not have a position to receive lithium ions, the lithium ions will precipitate on the surface of the negative electrode, forming lithium dendrites, piercing the diaphragm and causing a short circuit in the battery. Therefore, when designing lithium batteries, the negative electrode often needs to be over-designed to avoid such situations. However, the current margin area design still makes it easy for lithium to precipitate at the edge of the negative electrode, forming lithium dendrites, which affects the battery life. Summary of the invention

[0003] The first objective of the present invention is to provide a new technical solution for a negative electrode plate, which can at least solve the technical problem that lithium is easily deposited on the edge of the existing negative electrode plate.

[0004] The second object of the present invention is to provide a new technical solution for the preparation of negative electrode plates.

[0005] The third object of the present invention is to provide a new technical solution for batteries.

[0006] The fourth object of the present invention is to provide a new technical solution for electrical equipment.

[0007] According to a first aspect of the present invention, there is provided a negative electrode plate, comprising: a current collector, having a main region and a surplus region on at least one side surface of the current collector in a thickness direction, the surplus region being located at the periphery of the main region; wherein the main region is provided with a negative electrode active material layer, the surplus region is provided with a diffusion inhibition layer, the diffusion inhibition layer comprising a first negative electrode active material and an insulating material.

[0008] Optionally, the current collector has a first surface and a second surface that are oppositely arranged in the thickness direction thereof, and both the first surface and the second surface have the main region and the residual region.

[0009] Optionally, in the diffusion suppression layer, the insulating material accounts for 30% to 90% by mass.

[0010] Optionally, the insulating material includes polymer material and / or ceramic material.

[0011] Optionally, the ceramic material includes one or a combination of magnesium oxide, aluminum oxide, zirconium oxide, beryllium oxide, silicon oxide, silicate, borate, and phosphate.

[0012] Optionally, the polymer material includes one or a combination of polyethylene, polypropylene, polyetheramide, polytetrafluoroethylene, polyimide, polyvinylidene fluoride, polyvinyl alcohol, polyacrylate, and polyaniline.

[0013] Optionally, the diffusion suppression layer further includes a first binder and a first thickener.

[0014] Optionally, the negative electrode active material layer includes a second negative electrode active material, a conductive agent, a second binder and a second thickener.

[0015] Optionally, the first negative electrode active material is the same as the second negative electrode active material, the first binder is the same as the second binder, and the first thickener is the same as the second thickener.

[0016] Optionally, the width of the diffusion suppression layer is K, 0mm<K≤5mm.

[0017] According to a second aspect of the present invention, there is provided a method for preparing a negative electrode sheet, characterized in that it comprises: obtaining a current collector, wherein at least one side surface of the current collector in the thickness direction has the main region and the surplus region, and the surplus region is located at the periphery of the main region; setting a first slurry in the surplus region, and setting a second slurry in the main region, to obtain the negative electrode sheet, wherein the first slurry comprises the first negative electrode active material and the insulating material, and the second slurry comprises a negative electrode active material.

[0018] According to a third aspect of the present invention, a battery is provided, comprising the above-mentioned negative electrode plate or a negative electrode plate prepared by the above-mentioned method for preparing a negative electrode plate.

[0019] According to a fourth aspect of the present invention, there is provided an electrical device comprising the above-mentioned battery.

[0020] According to the negative electrode plate of the present invention, by setting the diffusion inhibition layer in the surplus area to include a mixture of the first negative electrode active material and the insulating material, the diffusion inhibition layer can both receive the embedded lithium ions and inhibit the diffusion of lithium ions to a certain extent, thereby effectively alleviating the problem of lithium deposition at the edge of the negative electrode plate, and further extending the number of cycles and service life of the lithium-ion battery.

[0021] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0023] Figure 1 is a schematic structural diagram of a negative electrode sheet according to an embodiment of the present invention;

[0024] Figure 2 is a schematic structural diagram of a current collector substrate containing a negative electrode active material layer according to an embodiment of the present invention;

[0025] Figure 3 is a schematic structural diagram of a current collector substrate containing a negative electrode active material layer according to another embodiment of the present invention;

[0026] Figure 4 is a schematic structural diagram of a negative electrode plate substrate according to an embodiment of the present invention;

[0027] Figure 5 It is a schematic structural diagram of a negative electrode plate substrate according to another embodiment of the present invention.

[0028] Reference numerals:

[0029] 100. Negative electrode;

[0030] 10. Negative electrode active material layer; 20. Diffusion inhibition layer; 30. Insulating layer;

[0031] a. Current collector substrate. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0033] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0034] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0035] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0036] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0037] First, the negative electrode sheet 100 according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0038] like Figure 1 As shown, the negative electrode sheet 100 according to an embodiment of the present invention includes a current collector.

[0039] Specifically, a main region and a residual region are provided on the surface of at least one side in the thickness direction of the current collector, and the residual region is located at the periphery of the main region; wherein the main region is provided with a negative electrode active material layer 10, and the residual region is provided with an inhibition diffusion layer 20, and the inhibition diffusion layer 20 includes a first negative electrode active material and an insulating material.

[0040] In other words, if Figure 1 As shown, the negative electrode plate 100 according to an embodiment of the present invention is mainly used in lithium-ion batteries, and the negative electrode plate 100 mainly includes a current collector, a negative electrode active material layer 10 and an inhibition diffusion layer 20, wherein the current collector has a first surface and a second surface arranged oppositely in its own thickness direction, and the first surface and / or the second surface of the current collector includes a main area and a surplus area, wherein the surplus area is located on one side or multiple sides of the periphery of the main area, and the surplus area can be straight, L-shaped or U-shaped, etc. The main area theoretically refers to the area where the negative electrode plate 100 overlaps with the positive electrode plate, and its area is the same as the area of ​​one side of the thickness direction of the positive electrode plate, and the surplus area refers to the area where the negative electrode plate 100 does not overlap with the positive electrode plate, that is, the edge area of ​​the negative electrode plate 100, the negative electrode active material layer 10 is arranged in the main area of ​​the current collector, and the inhibition diffusion layer 20 is arranged in the surplus area of ​​the current collector.

[0041] The diffusion suppression layer 20 is configured as a mixed material layer including a first negative electrode active material and an insulating material, wherein the first negative electrode active material can ensure that the diffusion suppression layer 20 can receive embedded lithium ions, and the insulating material can ensure that the diffusion suppression layer 20 can effectively suppress the diffusion of lithium ions, so that the diffusion suppression layer 20 can both receive embedded lithium ions and suppress the diffusion of lithium ions to a certain extent.

[0042] Therefore, according to the negative electrode plate 100 of the embodiment of the present invention, by setting the diffusion suppression layer 20 in the surplus area to include a mixture of the first negative electrode active material and the insulating material, the diffusion suppression layer 20 can both receive the embedded lithium ions and suppress the diffusion of lithium ions to a certain extent, thereby effectively alleviating the problem of lithium deposition at the edge of the negative electrode plate 100, and further extending the cycle number and service life of the lithium-ion battery.

[0043] In some optional examples of the present invention, the current collector may be a copper foil, and the copper foil may be a carbon-coated copper foil.

[0044] According to some embodiments of the present invention, a lug region is provided on one side of the periphery of the main body region of the current collector, the periphery of the main body region of the current collector excluding the lug region is a residual region, and an insulating layer 30 is provided on the lug region close to the main body region.

[0045] In some specific embodiments of the present invention, the current collector has a first surface and a second surface that are oppositely disposed in the thickness direction, and both the first surface and the second surface include a main body region and a residual region.

[0046] That is to say, the surface of the current collector on both sides in the thickness direction is provided with a main area and a residual area, and the main area and the residual area on both sides of the current collector are correspondingly provided with a negative electrode active material layer 10 and a diffusion inhibition layer 20, thereby alleviating the problem of lithium deposition at the edge of the negative electrode sheet 100 on both sides in the thickness direction of the negative electrode sheet 100, and can further extend the number of cycles and service life of the lithium-ion battery.

[0047] According to an embodiment of the present invention, in the diffusion suppression layer, the mass proportion of the insulating material is 30% to 90%.

[0048] In other words, the mass of the insulating material accounts for a mass proportion of X in the diffusion inhibition layer. If X is too low, the effect of inhibiting the diffusion of lithium ions is poor, and a part of the lithium ions will still diffuse through the negative electrode active material to the edge of the negative electrode sheet 100, that is, the area of ​​the negative electrode sheet 100 corresponding to the diffusion inhibition zone; if X is too high, the effect of receiving the embedded lithium ions is poor, and a part of the lithium ions will still be deposited at the edge of the negative electrode sheet 100.

[0049] Therefore, the mass proportion X of the insulating material in the diffusion suppression layer is taken in the range of 30% to 90%, that is, when X is 30%, 40%, 50%, 60%, 70%, 80% or 90%, the diffusion suppression layer 20 can effectively suppress the diffusion of lithium ions and at the same time receive embedded lithium ions, which can effectively avoid lithium deposition at the edge of the negative electrode plate 100 and ensure the performance of the battery.

[0050] In some optional examples of the present invention, the first negative electrode active material may be a carbon material, a silicon-based material, a tin-based material, or a combination of one or more of lithium titanate. When the first negative electrode active material is a carbon material, it may be a combination of one or more of graphite, carbon fiber, soft carbon, hard carbon, mesophase carbon microspheres, and graphene; when the first negative electrode active material is a silicon-based material, it may be a combination of one or more of elemental silicon, silicon oxide, silicon alloy, and composite silicon; when the first negative electrode active material is a tin-based material, it may be a combination of one or more of tin oxide and tin alloy.

[0051] According to an embodiment of the present invention, the insulating material includes a polymer material and / or a ceramic material.

[0052] That is to say, the insulating material can be a polymer material, a ceramic material, or a combination of a polymer material and a ceramic material, all of which have good insulating properties, and thus can have a good inhibitory effect and ensure the various performances of the battery.

[0053] According to one embodiment of the present invention, the ceramic material includes one or a combination of magnesium oxide, aluminum oxide, zirconium oxide, beryllium oxide, silicon oxide, silicate, borate, and phosphate.

[0054] Specifically, when the insulating material is a ceramic material, the insulating material can be one or a combination of magnesium oxide, aluminum oxide, zirconium oxide, beryllium oxide, silicon oxide, silicate, borate, and phosphate. These materials have good chemical stability and high temperature performance, and can ensure the performance of the battery under extreme conditions.

[0055] In some specific embodiments of the present invention, the polymer material includes one or a combination of polyethylene, polypropylene, polyetheramide, polytetrafluoroethylene, polyimide, polyvinylidene fluoride, polyvinyl alcohol, polyacrylate, polyaniline, etc.

[0056] Specifically, when the insulating material is a polymer material, the insulating material may be one or a combination of polyethylene, polypropylene, polyetheramide, polytetrafluoroethylene, polyimide, polyvinylidene fluoride, polyvinyl alcohol, polyacrylate, polyaniline, etc.

[0057] According to one embodiment of the present invention, the diffusion suppression layer 20 further includes a first binder and a first thickener.

[0058] That is to say, the diffusion suppression layer 20 mainly includes a first negative electrode active material, an insulating material, a first binder and a first thickener. Among them, the first binder can bind the first negative electrode active material, the insulating material and the current collector together, which can ensure that the battery can maintain stable performance during the charge and discharge process, and can play a role of dispersion and thickening, which is conducive to the uniform distribution of the first negative electrode active material and the insulating material, which can ensure the reliability of the diffusion suppression layer 20, and is also conducive to the preparation of a first slurry suitable for coating; the first thickener can increase the viscosity of the first slurry to make it within a suitable viscosity range, making the first slurry easier to shape, which can effectively improve the shape and adhesion of the first slurry, and can play a role of dispersion, which is conducive to the uniform distribution of the first negative electrode active material and the insulating material, and can ensure the reliability of the diffusion suppression layer 20.

[0059] In some specific embodiments of the present invention, the negative electrode active material layer 10 includes a second negative electrode active material, a conductive agent, a second binder, and a second thickener, so that the conductivity and structural stability of the negative electrode active material layer 10 can be ensured.

[0060] In some embodiments of the present invention, the second negative electrode active material, the second binder, and the second thickener in the negative electrode active material layer 10 are the same as the first negative electrode active material, the second binder, and the second thickener in the diffusion inhibition layer 20 .

[0061] In other words, the material of the diffusion suppression layer 20 is substantially the same as that of the negative electrode active material layer 10. Specifically, the negative electrode active material layer 10 includes a second negative electrode active material, a conductive agent, a second binder, and a second thickener. The difference between the diffusion suppression layer 20 and the negative electrode active material layer 10 is that the conductive agent is replaced by an insulating material, and the other materials are the same as those of the negative electrode active material layer 10, thereby facilitating the preparation of the negative electrode plate 100 and simplifying the materials required for the negative electrode plate 100.

[0062] According to one embodiment of the present invention, the width of the diffusion suppression layer 20 is K, 0 mm<K≤5 mm.

[0063] Specifically, the width of the diffusion suppression layer 20 is K, that is, the distance between the side of the diffusion suppression layer 20 close to the negative electrode active material layer 10 and the side of the diffusion suppression layer 20 away from the negative electrode active material layer 10 is K. If the value of K is too large, the size of the negative electrode sheet 100 will be too large, and the effect of alleviating the lithium deposition of the negative electrode sheet 100 will not be improved. In this embodiment, 0mm<K≤5mm, for example, K can be 1mm, 2mm, 3mm, 4mm and 5mm, etc., and the K value within this range can not only effectively alleviate the problem of lithium deposition of the negative electrode sheet 100, but also avoid the size of the negative electrode sheet 100 being too large.

[0064] In summary, according to the negative electrode plate 100 of the embodiment of the present invention, by setting the diffusion suppression layer 20 in the surplus area to a mixture including the first negative electrode active material and the insulating material, the diffusion suppression layer 20 can both receive the embedded lithium ions and suppress the diffusion of lithium ions to a certain extent, thereby effectively alleviating the problem of lithium deposition at the edge of the negative electrode plate 100, and further extending the cycle times and service life of the lithium-ion battery.

[0065] An embodiment of the present invention further provides a method for preparing a negative electrode plate 100 , which can be used to prepare the negative electrode plate 100 described in any of the above embodiments. The preparation method includes: steps 100 to 300 .

[0066] Step 100: Obtain a current collector having a main region and a residual region on at least one side surface of the current collector in a thickness direction, wherein the residual region is located at the periphery of the main region.

[0067] Step 200: disposing a first slurry in the surplus area and a second slurry in the main area to obtain a negative electrode sheet, wherein the first slurry includes a first negative electrode active material and an insulating material, and the second slurry includes a negative electrode active material.

[0068] Specifically, using copper foil or carbon-coated copper foil as the current collector, the steps of coating the first slurry and the second slurry include but are not limited to the following situations:

[0069] Case 1: When preparing the negative electrode sheet 100, the first slurry can be applied to the remaining area of ​​the current collector by using a coating device. After the first slurry on the remaining area is dried, the current collector containing the diffusion inhibition layer 20 can be obtained. Then, the second slurry can be applied to the main area of ​​the current collector containing the diffusion inhibition layer 20 by using a coating device. After the second slurry on the main area is dried, the current collector containing the negative active material layer 10 and the diffusion inhibition layer 20, i.e., the negative electrode sheet 100, can be obtained.

[0070] Case 2: When preparing the negative electrode sheet 100, the second slurry can be firstly coated on the main area of ​​the current collector by using a coating device. After the second slurry on the main area is dried, a current collector containing the negative electrode active material layer 10 can be obtained. Then, the first slurry can be coated on the remaining area of ​​the current collector containing the negative electrode active material layer 10 by using a coating device. After the first slurry on the remaining area is dried, a current collector containing the negative electrode active material layer 10 and the diffusion inhibition layer 20, i.e., the negative electrode sheet 100, can be obtained.

[0071] In this embodiment, the first slurry and the second slurry can be dried by oven drying. The first slurry mainly includes a first negative electrode active material and an insulating material, so that the diffusion inhibition layer 20 contains the first negative electrode active material and the insulating material, wherein the first negative electrode active material can ensure that the diffusion inhibition layer 20 can receive embedded lithium ions, and the insulating material can ensure that the diffusion inhibition layer 20 can effectively inhibit the diffusion of lithium ions, so that the diffusion inhibition layer 20 can both receive embedded lithium ions and inhibit the diffusion of lithium ions to a certain extent.

[0072] In some optional examples of the present invention, the first negative electrode active material, the insulating material, the first binder, the first thickener and water are mixed in a certain proportion to obtain the first slurry.

[0073] Furthermore, the type and content of the materials included in the first negative electrode active material and the second negative electrode active material may be the same, and they may be one or a combination of carbon materials, silicon-based materials, tin-based materials, and lithium titanate. When the first negative electrode active material and the second negative electrode active material are carbon materials, they may be one or a combination of graphite, carbon fiber, soft carbon, hard carbon, mesophase carbon microspheres, and graphene; when the first negative electrode active material and the second negative electrode active material are silicon-based materials, they may be one or a combination of elemental silicon, silicon oxide, silicon alloy, and composite silicon; when the first negative electrode active material and the second negative electrode active material are tin-based materials, they may be one or a combination of tin oxide and tin alloy.

[0074] Therefore, according to the method for preparing the negative electrode plate 100 of the embodiment of the present invention, by setting the first slurry coated on the surplus area to a slurry including the first negative electrode active material and the insulating material, the diffusion inhibition layer 20 of the prepared negative electrode plate 100 can contain the first negative electrode active material and the insulating material, so that the diffusion inhibition layer 20 can both receive the embedded lithium ions and inhibit the diffusion of lithium ions to a certain extent, thereby effectively alleviating the problem of lithium precipitation in the surplus area, and further extending the number of cycles and the service life of the lithium-ion battery.

[0075] According to one embodiment of the present invention, the current collector is formed by cutting the current collector substrate a, and the current collector substrate a has a plurality of main regions and a plurality of residual regions.

[0076] That is to say, the area of ​​the current collector substrate a is relatively large. For example, the current collector substrate a can be a coil, so that the current collector substrate a can include the main area and the residual area of ​​the current collector of multiple negative electrode sheets 100, which is conducive to the batch preparation of negative electrode sheets 100 and can effectively improve the preparation efficiency of the negative electrode sheets 100.

[0077] In some specific embodiments of the present invention, the current collector substrate a has a tab region required by the negative electrode plate 100, and when the first slurry is applied by a coating device, the current collector substrate a moves along a first direction, which is the length direction of the current collector substrate a. Figure 3 and Figure 4 As shown, when the tab area is distributed along the first direction, the first slurry is applied to multiple surplus areas by an intermittent coating method (i.e., the slurry is not applied continuously on the current collector substrate a, but is applied at a certain time interval), so as to avoid the tab area from being coated with the first slurry and ensure the coating efficiency; as shown Figure 2 and Figure 5As shown, when the tab area is distributed along the second direction (i.e., the width direction of the current collector substrate a), the remaining area extending along the first direction can be coated with the first slurry by a continuous coating method, and the remaining area extending along the second direction can be coated with the first slurry by an intermittent coating method, thereby ensuring the coating efficiency; after the first slurry on the remaining area is dried, the current collector substrate a containing the diffusion inhibition layer 20 can be obtained.

[0078] Then, the second slurry is applied to the main area of ​​the current collector substrate a containing the diffusion inhibition layer 20 by an intermittent coating method. After the second slurry on the main area is dried, a negative electrode sheet substrate containing multiple negative electrode active material layers 10 and multiple diffusion inhibition layers can be obtained. Subsequently, the tab area on the negative electrode sheet substrate is insulated, for example, an insulating layer is coated on the tab area close to the main area. Finally, it is cut according to the set specifications. After cutting, a current collector containing the negative electrode active material layer 10 and the diffusion inhibition layer 20, that is, a negative electrode sheet 100, can be obtained.

[0079] According to some embodiments of the present invention, when preparing the negative electrode sheet 100, first, the current collector substrate a is moved along the first direction, and the coating equipment adopts an intermittent coating method to coat the second slurry on the current collector substrate a. The area coated with the second slurry is the main area. Since the second slurry is coated in an intermittent manner, the required margin area can be reserved. After the second slurry on the main area is dried, the current collector substrate a containing multiple negative active material layers 10 can be obtained.

[0080] like Figure 3 and Figure 4 As shown, when the tab area is distributed along the first direction, the first slurry is applied to multiple surplus areas by intermittent coating, so as to avoid the tab area from being coated with the first slurry and ensure the coating efficiency; Figure 2 and Figure 5 As shown, when the tab area is distributed along the second direction (i.e., the width direction of the current collector substrate a), the remaining area extending along the first direction can be coated with the first slurry by a continuous coating method, and the remaining area extending along the second direction can be coated with the first slurry by an intermittent coating method, thereby ensuring the coating efficiency; after the first slurry on the remaining area is dried, the current collector substrate a containing the negative electrode active material layer 10 and the diffusion inhibition layer 20, i.e., the negative electrode sheet substrate, can be obtained.

[0081] Then, the tab area on the negative electrode sheet substrate is insulated, for example, an insulating layer is coated on the tab area close to the main body area, and finally cut according to the set specifications. After cutting, a current collector containing a negative electrode active material layer 10 and a diffusion inhibition layer 20, i.e., a negative electrode sheet 100, can be obtained.

[0082] In some specific embodiments of the present invention, the margin regions between the main body regions are adjacent.

[0083] That is to say, the surplus area between two main areas close to each other can be adjacent to each other as a whole, that is, there is no gap between the surplus areas corresponding to the two negative electrode sheets 100, so that the current collector substrate a can be fully utilized and the utilization rate of the material can be improved.

[0084] In some optional examples of the present invention, the second negative electrode active material, the conductive agent, the second binder, the second thickener and water are mixed in a certain proportion to prepare the second slurry.

[0085] In this embodiment, the first slurry is different from the second slurry in that the first slurry can be prepared by replacing the conductive agent in the material required for the second slurry with an insulating material, that is, the insulating material is mixed with the negative electrode active material and configured together with a binder and a thickener to form the first slurry.

[0086] The embodiment of the present invention further provides a battery, comprising the negative electrode sheet 100 described in any of the above embodiments, or the negative electrode sheet 100 prepared by the method for preparing the negative electrode sheet 100 described in any of the above embodiments. Since the negative electrode sheet 100 and the preparation method thereof according to the embodiment of the present invention have the above technical effects, the battery according to the embodiment of the present invention also has the corresponding technical effects, which will not be described in detail in this embodiment.

[0087] Specifically, the battery according to the embodiment of the present invention mainly includes a negative electrode sheet 100, a positive electrode sheet, a separator and an electrolyte. The negative electrode sheet 100 is the negative electrode sheet 100 described in any of the above embodiments, or the negative electrode sheet 100 prepared by the method for preparing the negative electrode sheet 100 described in any of the above embodiments. The negative electrode sheet 100 includes a negative electrode active material layer 10, a diffusion inhibition layer 20, an insulating region and a current collector. The negative electrode active material layer 10 can be arranged on one surface or both surfaces of the current collector; the current collector is not limited, and preferably, the current collector is a copper foil.

[0088] Furthermore, the insulating material added to the diffusion inhibition layer 20 can be a combination of one or more of a polymer material (i.e., a polymer material) and a ceramic material; when the insulating material is a polymer material, it can be a combination of one or more of polyethylene, polypropylene, polyether amide, polytetrafluoroethylene, polyimide, polyvinylidene fluoride, polyvinyl alcohol, polyacrylate, polyaniline, etc.; when the insulating material is a ceramic material, it can be a combination of one or more of magnesium oxide, aluminum oxide, zirconium oxide, beryllium oxide, silicon oxide, silicate, borate, phosphate, etc.

[0089] The positive electrode plate includes a positive electrode active layer and a current collector. The positive electrode active layer can be arranged on one surface or both surfaces of the current collector. The current collector is not limited. Preferably, the current collector is aluminum foil, and more preferably, the current collector is carbon-coated aluminum foil. The positive electrode active material in the positive electrode active layer can be one or a combination of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium phosphate containing olivine structure. The diaphragm includes but is not limited to one or a composite film of polyethylene, polypropylene, and polyvinylidene fluoride. The electrolyte is not limited and can be selected according to actual conditions.

[0090] The effect of the negative electrode sheet 100 according to the embodiment of the present invention is described in detail below in conjunction with a specific experimental group.

[0091] Edge lithium deposition test method:

[0092] 1. Prepare 10 batteries for each magnification;

[0093] 2. After charging the battery to 100% SOC at 0.5C at 25°C, place it at 45°C (shorten the experimental time) for 10 days;

[0094] 3. Take the battery out from 45℃, place it at room temperature for 8h to restore it to room temperature, discharge it at 0.5C to 0% SOC state, and place it for 10min;

[0095] 4. Charge at 1C, 2C, 4C, and 6C rates to the cut-off voltage of the battery, and discharge at 1 / 3C;

[0096] 5. Disassemble all batteries and check whether there is lithium deposition on the edge of the negative electrode.

[0097] It should be noted that the area of ​​lithium deposition on the edge of the negative electrode plate 100 after the experiment is measured, and the ratio of the lithium deposition area to the electrode area is calculated. A ratio less than or equal to 5% is considered mild lithium deposition, and a ratio greater than 5% is considered severe lithium deposition.

[0098] Experimental Group 1:

[0099] The negative electrode sheet was prepared according to the preparation method provided above.

[0100] Among them: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 72:25:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0101] After lithium iron phosphate (LiFePO4), conductive agent (superP-Li), and binder (PVDF) are mixed in a ratio of 96:1.5:2.5, the powder and NMP are stirred into a positive electrode slurry in a vacuum mixer and evenly coated on aluminum foil (i.e., positive electrode current collector).

[0102] Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to prepare an electrolyte.

[0103] A polypropylene diaphragm was selected to prepare a 2Ah stacked battery, and an edge lithium deposition test was performed according to the test method provided above to check whether lithium deposition occurs at the edge of the negative electrode.

[0104] Experimental Group 2

[0105] The negative electrode sheet was prepared according to the preparation method provided above.

[0106] Wherein: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 67:30:2:1;

[0107] The second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0108] The other steps were the same as those in Experimental Group 1.

[0109] Experimental Group 3:

[0110] The negative electrode sheet was prepared according to the preparation method provided above.

[0111] Among them: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 57:40:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0112] The other steps were the same as those in “Experimental Group 1”.

[0113] Experimental Group 4:

[0114] The negative electrode sheet was prepared according to the preparation method provided above.

[0115] Among them: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 47:50:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0116] The other steps were the same as those in “Experimental Group 1”.

[0117] Experimental Group 5:

[0118] The negative electrode sheet was prepared according to the preparation method provided above.

[0119] Among them: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 37:60:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0120] The other steps were the same as those in “Experimental Group 1”.

[0121] Experimental Group 6:

[0122] The negative electrode sheet was prepared according to the preparation method provided above.

[0123] Among them: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 27:70:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0124] The other steps were the same as those in “Experimental Group 1”.

[0125] Experimental Group 7:

[0126] The negative electrode sheet was prepared according to the preparation method provided above.

[0127] Among them: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 17:80:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0128] The other steps were the same as those in “Experimental Group 1”.

[0129] Experimental Group 8:

[0130] The negative electrode sheet was prepared according to the preparation method provided above.

[0131] Among them: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 7:90:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0132] The other steps were the same as those in “Experimental Group 1”.

[0133] Experimental Group 9:

[0134] The negative electrode sheet was prepared according to the preparation method provided above.

[0135] Wherein: the first slurry ratio: graphite: aluminum oxide: thickener (CMC): binder (SBR) = 2:95:2:1;

[0136] The second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0137] The other steps were the same as those in Experimental Group 1.

[0138] Experimental Group 10:

[0139] The negative electrode sheet was prepared according to the preparation method provided above.

[0140] Wherein: the first slurry ratio: graphite: polytetrafluoroethylene: thickener (CMC): binder (SBR) = 72:25:2:1;

[0141] The second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1;

[0142] The other steps were the same as those in Experimental Group 1.

[0143] Experimental Group 11:

[0144] The negative electrode sheet was prepared according to the preparation method provided above.

[0145] Among them: the first slurry ratio: graphite: polytetrafluoroethylene: thickener (CMC): binder (SBR) = 67:30:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1;

[0146] The other steps were the same as those in “Experimental Group 1”.

[0147] Experimental Group 12:

[0148] The negative electrode sheet was prepared according to the preparation method provided above.

[0149] Among them: the first slurry ratio: graphite: polytetrafluoroethylene: thickener (CMC): binder (SBR) = 7:90:2:1; the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1.

[0150] The other steps were the same as those in “Experimental Group 1”.

[0151] Experimental Group 13:

[0152] The negative electrode sheet was prepared according to the preparation method provided above.

[0153] Among them: the difference from experimental group 1 is that the first slurry ratio: graphite: polytetrafluoroethylene: thickener (CMC): binder (SBR) = 2:95:2:1;

[0154] The second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1;

[0155] Prepare a negative electrode sheet according to the preparation method provided above;

[0156] The other steps were the same as those in Experimental Group 1.

[0157] Control group 1

[0158] The negative electrode sheet was prepared according to the preparation method provided above.

[0159] Wherein: the second slurry ratio: graphite: conductive agent (superP-Li): thickener (CMC): binder (SBR) = 95:1:2:1;

[0160] The difference from Experimental Group 1 is that the first slurry is not set on the area margin, and the second slurry is directly used for coating.

[0161] The other steps of the experimental group were the same as those of experimental group 1.

[0162] The test results of the above experimental group and control group are shown in the following table

[0163] Table 1: Test results of lithium deposition on negative electrode

[0164]

[0165] It should be noted that, during the preparation process of the batteries used in the experimental group and the control group, there will inevitably be problems with the misalignment of some positive and negative pole pieces (caused by assembly errors), and some of the positive pole pieces just correspond to the main area of ​​the negative pole pieces. It can be seen from Table 1 that when the proportion of the insulating material in the diffusion inhibition zone is within 30%-90%, the phenomenon of unilateral lithium deposition in the normal production process can be alleviated; when the proportion of the insulating material in the diffusion inhibition zone is outside this range, some batteries will experience unilateral lithium deposition, which should be understood by those skilled in the art.

[0166] In summary, the negative electrode plate 100 of the embodiment of the present invention, by setting the diffusion suppression layer 20 in the surplus area to a mixture including the first negative electrode active material and the insulating material, allows the diffusion suppression layer 20 to both receive embedded lithium ions and to a certain extent suppress the diffusion of lithium ions, thereby effectively alleviating the problem of lithium plating in the surplus area, thereby extending the number of cycles and service life of the lithium-ion battery, and when the mass of the insulating material accounts for 30% to 90% of the sum of the mass of the first negative electrode active material and the insulating material, the negative electrode plate 100 of the embodiment of the present invention will not have the problem of lithium plating.

[0167] The embodiment of the present invention further provides an electric device, including the battery described in any of the above embodiments. Since the negative electrode sheet 100 and the preparation method thereof according to the embodiment of the present invention have the above technical effects, the electric device according to the embodiment of the present invention also has the corresponding technical effects, which will not be described in detail in this embodiment.

[0168] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A negative electrode plate, characterized in that: include: A current collector, wherein the current collector has a main body region and a surplus region on at least one side surface in a thickness direction, wherein the surplus region is located at the periphery of the main body region; The main body region is provided with a negative electrode active material layer, the remaining region is provided with a diffusion inhibition layer, and the diffusion inhibition layer includes a first negative electrode active material and an insulating material.

2. The negative electrode sheet according to claim 1, characterized in that: The current collector has a first surface and a second surface that are oppositely disposed in a thickness direction thereof, and both the first surface and the second surface have the main body region and the residual region.

3. The negative electrode sheet according to claim 1 or 2, characterized in that: In the diffusion suppression layer, the insulating material accounts for 30% to 90% by mass.

4. The negative electrode sheet according to any one of claims 1 to 3, characterized in that: The insulating material includes polymer material and / or ceramic material.

5. The negative electrode sheet according to claim 4, characterized in that: The ceramic material includes one or a combination of magnesium oxide, aluminum oxide, zirconium oxide, beryllium oxide, silicon oxide, silicate, borate, and phosphate.

6. The negative electrode sheet according to claim 4 or 5, characterized in that: The polymer material includes one or a combination of polyethylene, polypropylene, polyetheramide, polytetrafluoroethylene, polyimide, polyvinylidene fluoride, polyvinyl alcohol, polyacrylate, and polyaniline.

7. The negative electrode sheet according to any one of claims 1 to 6, characterized in that: The diffusion suppression layer further includes a first binder and a first thickener.

8. The negative electrode sheet according to claim 7, characterized in that: The negative electrode active material layer includes a second negative electrode active material, a conductive agent, a second binder, and a second thickener.

9. The negative electrode sheet according to claim 8, characterized in that: The first negative electrode active material is the same as the second negative electrode active material, the first binder is the same as the second binder, and the first thickener is the same as the second thickener.

10. The negative electrode sheet according to any one of claims 1 to 9, characterized in that: The width of the diffusion suppression layer is K, 0mm<K≤5mm.

11. A method for preparing a negative electrode sheet according to any one of claims 1 to 10, characterized in that: include: Obtaining a current collector, wherein at least one side surface of the current collector in the thickness direction has the main body region and the residual region, and the residual region is located at the periphery of the main body region; The first slurry is disposed in the surplus area, and the second slurry is disposed in the main area to obtain the negative electrode sheet, wherein the first slurry includes the first negative electrode active material and the insulating material, and the second slurry includes the negative electrode active material.

12. A battery, characterized in that: A negative electrode sheet comprising the negative electrode sheet according to any one of claims 1 to 10 or a negative electrode sheet prepared by the method for preparing the negative electrode sheet according to claim 11.

13. An electrical equipment, characterized in that: Comprising the battery as claimed in claim 12.

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