Negative plate, battery and electric equipment

Abstract

The utility model relates to a negative electrode plate, a battery and electric equipment. The negative electrode plate comprises a negative electrode current collector, a first negative electrode active material layer and a second negative electrode active material layer, the first surface and the second surface of the negative electrode current collector are respectively provided with one first negative electrode active material layer, first active particles are arranged in the first negative electrode active material layers, and the first active particles are uniformly distributed in the first negative electrode active material layers; a first included angle is formed between the first active particulate matter and the first surface; the second negative electrode active material layer is arranged on the surface of the first negative electrode active material layer, and second active particles are arranged in the second negative electrode active material layer; wherein the first surface and the second surface of the negative electrode current collector are two side surfaces in the thickness direction of the negative electrode current collector. The lithium ion battery has the advantages that lithium ions can be conveniently diffused, so that the battery has higher rate capability.

Description

Technical Field

[0001] The present application relates to the technical field of battery equipment, and in particular to a negative electrode sheet, a battery and an electrical device. Background Art

[0002] At present, with the rapid development of the electric vehicle industry, the market has higher and higher requirements for the performance of pure electric vehicles, and the combination of power and long driving range has become the mainstream requirement. In lithium battery technology, the positive and negative electrodes of the battery cell are mostly formed by combining the current collector and the active material layer. After the active material side layer is coated on the current collector, it is dried and rolled to form the positive and negative electrodes.

[0003] In the related art, the active material layer on the negative electrode sheet of the battery is mostly coated with a single layer of negative electrode, and after rolling, the diffusion of lithium ions in the negative electrode sheet will be hindered, which makes it difficult to meet the high-rate performance requirements of the battery. Utility Model Content

[0004] The present application is proposed to solve the above-mentioned problems. According to one aspect of the present application, a negative electrode sheet is provided, which includes: a negative electrode collector, a first negative electrode active material layer and a second negative electrode active material layer; the first surface and the second surface of the negative electrode collector are respectively provided with a first negative electrode active material layer, and the first negative electrode active material layer is provided with first active particles, the first active particles are uniformly arranged in the first negative electrode active material layer, and a first angle is formed between the first active particles and the first surface; the second negative electrode active material layer is provided on the surface of the first negative electrode active material layer, and the second negative electrode active material layer is provided with second active particles; wherein the first surface and the second surface of the negative electrode collector are the two side surfaces in the thickness direction of the negative electrode collector.

[0005] Illustratively, at least a portion of the second active particles in the second negative electrode active material layer are parallel to the first surface of the negative electrode current collector.

[0006] Exemplarily, the second active particles are evenly arranged in the second negative electrode active material layer, and a second angle is formed between the second active particles and the first surface of the negative electrode current collector.

[0007] Exemplarily, the first active particles and the second active particles are both diamagnetic materials, the first angle is formed by a magnetic field applied to the first active particles, and the second angle is formed by a magnetic field applied to the second active particles.

[0008] Exemplarily, the absolute values ​​of the first angle and the second angle are 10°-90°.

[0009] Exemplarily, the first negative electrode active material layer further includes a first conductive agent and a first binder, and the mass proportion of the first active particles in the first negative electrode active material layer is greater than 95%.

[0010] Exemplarily, the second negative electrode active material layer also includes a second conductive agent and a second adhesive, and the mass proportion of the second active particles in the second negative electrode active material layer is greater than 95%; the content of the second adhesive in the second negative electrode active material layer is greater than the content of the first adhesive in the first negative electrode active material layer.

[0011] Illustratively, the negative electrode current collector comprises copper foil.

[0012] Exemplarily, the solid phase diffusion coefficient of lithium in the second negative electrode active material layer is greater than the solid phase diffusion coefficient of lithium in the first negative electrode active material layer.

[0013] According to another aspect of the present application, a battery is provided, the battery comprising a plurality of battery cells, the battery cells comprising a positive electrode sheet and the above-mentioned negative electrode sheet, the positive electrode sheet comprising a positive electrode active material layer and a positive electrode current collector.

[0014] According to another aspect of the present application, there is provided an electrical device, the electrical device comprising the above-mentioned battery.

[0015] A negative electrode sheet in the present application uses a double-layer active material layer, wherein a first negative electrode active material layer and a second negative electrode active material layer are respectively arranged on the surface of a negative electrode current collector; the double-layer active material layer can use a composite active material to meet the needs of the battery, and the first active particles are arranged obliquely in the first active material layer and form a first angle with the negative electrode current collector to facilitate the diffusion of lithium ions, so that the battery has a higher rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps.

[0017] Figure 1 A schematic diagram of the structure of the negative electrode sheet in Example 1 of the present application is shown.

[0018] Figure 2 A schematic diagram showing the arrangement of the first active particles and the second active particles in Example 1 of the present application is shown.

[0019] Figure 3A schematic diagram of the magnetic field in the first embodiment of the present application is shown.

[0020] Figure 4 A schematic diagram of the structure of the negative electrode sheet in the second embodiment of the present application is shown.

[0021] Figure 5 A schematic diagram showing the arrangement of the first active particles and the second active particles in the second embodiment of the present application is shown.

[0022] Figure 6 A schematic diagram of the magnetic field in the second embodiment of the present application is shown. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present application more obvious, the example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0024] Embodiment 1

[0025] like Figure 1 As shown, the embodiment of the present application provides a negative electrode sheet, which includes: a negative electrode current collector 1, a first negative electrode active material layer 11 and a second negative electrode active material layer 12. A first negative electrode active material layer 11 is provided on the first surface and the second surface of the negative electrode current collector 1, respectively, and a first active particle 13 is provided in the first negative electrode active material layer 11. The first active particle 13 is evenly arranged in the first negative electrode active material layer 11, and a first angle is formed between the first active particle 13 and the first surface. The second negative electrode active material layer 12 is provided on the surface of the first negative electrode active material layer 11, and a second active particle 14 is provided in the second negative electrode active material layer 12.

[0026] The first surface and the second surface of the negative electrode current collector 1 are two side surfaces in the thickness direction of the negative electrode current collector 1 .

[0027] The negative electrode sheet in the embodiment of the present application uses a double-layer active material layer, and the first negative electrode active material layer 11 and the second negative electrode active material layer 12 are respectively arranged on the surface of the negative electrode collector 1; the double-layer active material layer can use a composite active material to meet the needs of the battery, and the first active particle 13 is tilted in the first negative electrode active material layer 11 and forms a first angle with the negative electrode collector 1 to facilitate the diffusion of lithium ions so that the battery has a higher rate performance.

[0028] like Figure 1 and Figure 2 As shown, in the embodiment of the present application, the first active particles 13 are evenly arranged in the first negative electrode active material layer 11, and a first angle is formed between the first active particles 13 and the first surface. The absolute value of the first angle is 10°-90°, and in some embodiments the absolute value is 45°-90°.

[0029] Exemplarily, at least a portion of the second active particles 14 in the second negative electrode active material layer 12 are parallel to the first surface of the negative electrode current collector 1. It should be noted that the parallelism between the second active particles 14 and the first surface refers to the state after the negative electrode current collector 1 and the second negative electrode active material layer 12 are unfolded. Because after the first negative electrode active material layer 11 and the second negative electrode active material layer 12 are coated on the negative electrode current collector 1, they both need to go through the steps of drying and rolling. The second active particles 14 in the second negative electrode active material layer 12 are initially randomly arranged in the second active material layer. After rolling, the second active particles 14 are squeezed so that at least a portion of the second active particles 14 are parallel to the first surface of the negative electrode current collector 1. Specifically, as Figure 2 As shown, most of the second active particles 14 are parallel to the first surface. For example, the negative electrode current collector 1 can be a copper foil.

[0030] like Figure 1-Figure 3 As shown, the first active particle 13 is a diamagnetic material, and the first angle is formed by applying a magnetic field to the first active particle 13. The diamagnetic material used as the first active particle 13 can be high-capacity artificial graphite or natural graphite. When the magnetic field is applied to the first negative electrode active material layer 11 and the first active particle 13, the diamagnetic (or reverse magnetism) of the first active particle 13 causes the first active particle 13 to move in the first negative electrode active material layer 11, and finally to be regularly arranged according to the direction of the magnetic field strength.

[0031] Exemplarily, the application of the magnetic field and the coating of the first negative electrode active material layer 11 can be carried out simultaneously. The first negative electrode active material layer 11 is coated on the surface of the current collector, and a specified magnetic field is applied by a permanent magnet or an electromagnet during the coating process. The magnetic field strength is 0.1-2.5T, the gap between the magnets 2 is 1-20cm, and the magnetic field is inclined at an angle of 10°-90° to the copper foil. In this way, under the action of the magnetic field, the first active particles 13 will be regularly arranged according to the direction of the magnetic field strength. After that, a rolling process is required, and the angle of the first active particles 13 will change during the rolling process, but the first active particles 13 still have an inclination angle compared to the first surface of the negative electrode current collector 1, and the inclination angle is the first angle. It should be noted that Figure 2The first active particles 13 are magnified in the figure. It can be seen from the figure that there is an obvious angle between the first active particles 13 and the first surface of the negative electrode current collector 1. However, in fact, because the particle size of the first active particles 13 is small, it is difficult to see the tilt angle with the naked eye. However, multiple first active particles 13 will form a regular array under the action of the magnetic field, and a clear angle will also be formed between the same column of particles composed of multiple first active particles 13 and the first surface. The absolute value of the angle is 10°-90°.

[0032] For example, the first active particles 13 in the negative electrode sheet can be observed by using an electron microscope (Scanning Electron Microscope, SEM for short) to determine the arrangement and angle of the first active particles 13 .

[0033] After the first negative electrode active material layer 11 is coated on the negative electrode current collector 1, the second negative electrode active material layer 12 is bonded to the first negative electrode active material layer 11. The second active particulate matter 14 in the second negative electrode active material layer 12 is a high-rate negative electrode material, including but not limited to high-rate artificial graphite, hard carbon, soft carbon, mesophase carbon microspheres, etc.

[0034] In the negative electrode sheet of the embodiment of the present application, a high-capacity material (such as the high-capacity natural graphite and artificial graphite described above) is used as the first active particle 13 in the first negative electrode active material layer 11, and a high-rate negative electrode material is used as the second active particle 14 in the second negative electrode active material layer 12. In addition, when selecting the first active particle 13 and the second active particle 14, it is necessary to satisfy that the two have different lithium solid phase diffusion coefficients and gram capacities.

[0035] Specifically, the solid phase diffusion coefficient of lithium in the second negative electrode active material layer 12 is greater than the solid phase diffusion coefficient of lithium in the first negative electrode active material layer 11, and the gram capacity of the negative electrode active material in the first negative electrode active material layer 11 is greater than the gram capacity of the negative electrode active material in the second negative electrode active material layer 12. The ratio between the solid phase diffusion coefficient of lithium in the second negative electrode active material layer 12 and the solid phase diffusion coefficient of lithium in the first negative electrode active material layer 11 is not less than 1.2, and illustratively, the range of the ratio is 1.2-1000, which can improve the lithium insertion performance of the negative electrode sheet.

[0036] The composite active material layers on both sides of the negative electrode current collector 1 formed in the end can better meet the high capacity and high rate requirements of the battery. Such a negative electrode sheet that takes both capacity and rate into consideration is applied to lithium-ion batteries, which can solve the problems of high-power discharge and incompatibility of power in high-end passenger cars.

[0037] Exemplarily, the first negative electrode active material layer 11 in the embodiment of the present application further includes a first conductive agent and a first adhesive, and the mass proportion of the first active particulate matter 13 in the first negative electrode active material layer 11 is greater than 95%. Similarly, the second negative electrode active material layer 12 further includes a second conductive agent and a second adhesive, and the mass proportion of the second active particulate matter 14 in the second negative electrode active material layer 12 is greater than 95%. Exemplarily, the content of the second adhesive in the second negative electrode active material layer 12 is greater than the content of the first adhesive in the first negative electrode active material layer 11. That is to say, relatively more adhesive is added to the second negative electrode active material layer 12, so that the bonding force between the first negative electrode active material layer 11 and the second negative electrode active material layer 12 can be improved, thereby improving the cycle life of the battery to which the negative electrode sheet is applied.

[0038] Exemplarily, the first negative electrode active material layer 11 and the second negative electrode active material layer 12 further include a water binder, and the water binder may be styrene-butadiene rubber.

[0039] When coating the first negative electrode active material layer 11 and the second negative electrode active material layer 12 in the embodiment of the present application, the first negative electrode active material layer 11 is first coated on the surface of the negative electrode current collector 1, and a magnetic field is applied during the coating process to change the arrangement of the first active particles 13. After the first surface and the second surface are coated, the second negative electrode active material layer 12 is coated, and no magnetic field is applied during the coating process of the second negative electrode active material layer 12. After the coating work is completed, drying and rolling are performed to form the final negative electrode sheet.

[0040] The negative electrode sheet in the embodiment of the present application uses a double-layer active material layer, and the first negative electrode active material layer 11 and the second negative electrode active material layer 12 are respectively arranged on the surface of the negative electrode collector 1; the double-layer active material layer can use a composite active material to meet the needs of the battery, and the first active particle 13 is tilted in the first active material layer and forms a first angle with the negative electrode collector 1 to facilitate the diffusion of lithium ions so that the battery has a higher rate performance.

[0041] Embodiment 2

[0042] like Figure 4As shown, the embodiment of the present application provides a negative electrode sheet, which includes: a negative electrode current collector 1, a first negative electrode active material layer 11 and a second negative electrode active material layer 12. A first negative electrode active material layer 11 is provided on the first surface and the second surface of the negative electrode current collector 1, respectively, and a first active particle 13 is provided in the first negative electrode active material layer 11. The first active particle 13 is evenly arranged in the first negative electrode active material layer 11, and a first angle is formed between the first active particle 13 and the first surface. The second negative electrode active material layer 12 is provided on the surface of the first negative electrode active material layer 11, and a second active particle 14 is provided in the second negative electrode active material layer 12.

[0043] like Figure 4 and Figure 5 As shown, the difference from the above-mentioned embodiment 1 is that in the embodiment of the present application, the second active particles 14 are evenly arranged in the second negative electrode active material layer 12, and a second angle is formed between the second active particles 14 and the first surface of the negative electrode current collector 1.

[0044] Exemplarily, the absolute value of the second angle is 10°-90°, and the second angle is formed by applying a magnetic field to the second active particulate matter 14. The second active particulate matter 14, like the first active particulate matter 13, is a diamagnetic material. Exemplarily, both can select particles of artificial graphite or natural graphite. However, when selecting the first active particulate matter 13 and the second active particulate matter 14, it is necessary to satisfy that the two have different lithium solid phase diffusion coefficients and gram capacities. In addition, the first active particulate matter 13 selects high-capacity artificial graphite or natural graphite, and the second active particulate matter 14 selects high-rate artificial graphite or natural graphite.

[0045] like Figure 4-Figure 6 As shown, in the embodiment of the present application, both the first negative electrode active material layer 11 and the second negative electrode active material layer 12 need to apply a magnetic field to change the arrangement of the particles when coating. The first negative electrode active material layer 11 is first coated on the surface of the negative electrode current collector 1, and a magnetic field is applied during the coating process to change the arrangement of the first active particles 13. Then the second negative electrode active material layer 12 is coated, and a magnetic field is applied during the coating process of the second negative electrode active material layer 12. The two magnetic fields can be the same magnetic field or two magnetic fields. Alternatively, in one magnetic field, the first negative electrode active material layer 11 and the second negative electrode active material layer 12 are coated at the same time.

[0046] The magnetic field applied during coating of the second negative electrode active material layer 12 also needs to meet the following requirements: the magnetic field strength is 0.1-2.5 T, the gap between the magnets 2 is 1-20 cm, and the magnetic field and the copper foil are inclined at an angle of 10°-90°, so as to achieve uniform arrangement of the second active particles 14 in the second negative electrode active material layer 12.

[0047] After the coating of the first negative electrode active material layer 11 and the second negative electrode active material layer 12 is completed, drying and rolling are performed to form a final negative electrode sheet. In the negative electrode sheet, a first angle is formed between the first active particles 13 and the first surface of the negative electrode current collector 1, and a second angle is formed between the second active particles 14 and the first surface of the negative electrode current collector 1.

[0048] The negative electrode sheet in the embodiment of the present application uses a double-layer active material layer, and the first negative electrode active material layer 11 and the second negative electrode active material layer 12 are respectively arranged on the surface of the negative electrode collector 1; the double-layer active material layer can use a composite active material to meet the needs of the battery, and the first active particles 13 are tilted in the first active material layer and form a first angle with the negative electrode collector 1 to facilitate the diffusion of lithium ions so that the battery has a higher rate performance. In addition, the second active particles 14 in the second negative electrode active material layer 12 in the embodiment of the present application are also evenly arranged and form an angle with the negative electrode collector 1, which further indicates the diffusion ability of lithium ions and further improves the rate performance of the battery.

[0049] Embodiment 3

[0050] The embodiment of the present application provides a battery, which is a lithium-ion battery, including a plurality of battery cells, wherein the battery cells include a positive electrode sheet and the negative electrode sheet in the above-mentioned embodiment 1 or embodiment 2, and the positive electrode sheet includes a positive electrode active material layer and a positive electrode current collector. The positive electrode active material layer is located on both sides of the thickness direction of the positive electrode current collector, and the positive electrode current collector can be an aluminum foil. The positive electrode sheet and the negative electrode sheet are subjected to the steps of lamination, assembly, injection, formation, aging, etc. to obtain the battery. The embodiment of the present application also provides an electrical device, which includes the above-mentioned battery.

[0051] The following is a comparative introduction of the above-mentioned negative electrode sheet and battery in combination with specific battery parameters:

[0052] Experimental Group 1

[0053] The negative electrode sheet in the above-mentioned embodiment 1 was used in this experimental group. Specifically, the first negative electrode active material layer in the negative electrode sheet has a ratio of 95.5wt% (mass percentage) of high-capacity natural graphite, 1wt% of SP (conductive agent), 1.5wt% of CMC (binder), and 2wt% of SBR (water binder), and its solid content is 40wt%-45wt%. The second negative electrode active material layer has a ratio of 95.5wt% of high-rate artificial graphite, 1wt% of SP, 1.5wt% of CMC, and 2wt% of SBR, and its solid content is 40wt%-45wt%. Among them, the solid content represents the total mass percentage of each material in the water liquid after mixing and adding water.

[0054] During the coating process of the first negative electrode active material layer, the magnetic field strength is 1T, the inclination angle between the magnetic field line and the copper foil is 90°, the gap between the two poles of the magnet is 1cm, and the coating speed is 1m / min. After the coating of the first negative electrode active material layer is completed, the coating of the second negative electrode active material layer is carried out, and no magnetic field is applied during the coating process of the second negative electrode active material layer. After drying, the negative electrode sheet is obtained by rolling.

[0055] For the positive electrode sheet in the battery, lithium iron phosphate, acetylene black and polyvinylidene fluoride are added into a stirring tank in a mass ratio of 97.2:1.5:1.3, N-methylpyrrolidone solvent is added and stirred, and then passed through a 200-mesh sieve to prepare a positive electrode slurry with a solid content of 70wt%-75wt%; the slurry is coated on the positive electrode collector (aluminum foil) by a coating machine, dried, and rolled to obtain the positive electrode sheet.

[0056] The positive and negative electrode sheets are stacked, assembled, injected, formed, aged and other steps to obtain the lithium-ion battery of experimental group 1.

[0057] Experimental Group 2

[0058] In the experimental group, the first negative electrode active material layer has a ratio of 95.5wt% high-capacity natural graphite, 1wt% SP (conductive agent), 1.5wt% CMC (binder), and 2wt% SBR (water binder), and its solid content is 40wt%-45wt%. The second negative electrode active material layer has a ratio of 95.5wt% high-rate artificial graphite, 1wt% SP, 1.5wt% CMC, and 2wt% SBR, and its solid content is 40wt%-45wt%.

[0059] During the coating process of the first negative electrode active material layer and the second negative electrode active material layer, a magnetic field strength of 1T, a magnetic field line and a copper foil inclination angle of 90°, a magnet pole gap of 1cm, and a coating speed of 1m / min were applied. After coating and drying, the negative electrode sheet was obtained by roller pressing.

[0060] Preparation of positive electrode sheet: lithium iron phosphate, acetylene black and polyvinylidene fluoride are added into a stirring tank in a mass ratio of 97.2:1.5:1.3, N-methylpyrrolidone solvent is added, stirred and passed through a 200-mesh sieve to prepare a positive electrode slurry with a solid content of 70wt%-75wt%; the slurry is coated on the positive electrode collector (aluminum foil) by a coating machine, dried and rolled to obtain a positive electrode sheet.

[0061] The positive and negative electrode sheets are stacked, assembled, injected, formed, aged and other steps to obtain the lithium-ion battery of experimental group 2.

[0062] Control group

[0063] In the control group, the first negative electrode active material layer has a ratio of 95.5wt% high capacity natural graphite, 1wt% SP (conductive agent), 1.5wt% CMC (binder), 2wt% SBR (water binder), and a solid content of 40wt%-45wt%. The second negative electrode active material layer has a ratio of 95.5wt% high rate artificial graphite, 1wt% SP, 1.5wt% CMC, 2wt% SBR, and a solid content of 40wt%-45wt%.

[0064] After the first negative electrode active material layer is conventionally coated, the second negative electrode active material layer is conventionally coated. After drying, the negative electrode sheet is obtained by rolling.

[0065] Preparation of positive electrode sheet: lithium iron phosphate, acetylene black and polyvinylidene fluoride are added into a stirring tank in a mass ratio of 97.2:1.5:1.3, N-methylpyrrolidone solvent is added, stirred and passed through a 200-mesh sieve to prepare a positive electrode slurry with a solid content of 70wt%-75wt%; the slurry is coated on the positive electrode collector (aluminum foil) by a coating machine, dried and rolled to obtain a positive electrode sheet.

[0066] The positive and negative electrode sheets are stacked, assembled, injected, formed, aged and other steps to obtain a lithium-ion battery.

[0067] In experimental group 1: the graphite particles in the first negative electrode active material layer are arranged regularly and form a certain angle with the copper foil, and the graphite particles in the second negative electrode active material layer are arranged randomly and most of them are parallel to the copper foil.

[0068] In Experimental Group 2: the graphite particles in the first negative electrode active material layer and the second negative electrode active material layer are arranged regularly and form a certain angle with the copper foil, and there is no obvious boundary between the first negative electrode active material layer and the second negative electrode active material layer.

[0069] In the control group: the graphite particles in the first negative electrode active material layer and the second negative electrode active material layer are arranged randomly, and most of them are parallel to the copper foil.

[0070] OI value of graphite in each group: OI 实验组2 <OI 实验组1 <OI 对照组 Among them, the OI value represents the orientation index of graphite. The smaller the OI value, the higher the lithium ion diffusion rate and the better the charge and discharge performance.

[0071] For the above experimental group and control group, the microscopic arrangement of graphite particles can be tested by SEM equipment, and the OI value can be obtained by X-ray diffraction (XRD) equipment.

[0072] The batteries in the above groups also differ in diffusion impedance, cycle life, and high-rate charge and discharge retention rate, among which:

[0073] Diffusion impedance 实验组2 <Diffusion resistance 实验组1 <Diffusion resistance 对照组

[0074] Because the negative electrode sheets in Example 1 and Example 2 act on the active particles during the coating process, the arrangement of the active particles is changed, and the diffusion rate of lithium ions is changed. Because the negative electrode sheet, the first active particles and the second active particles in Example 2 are all subjected to a magnetic field, the battery in Experimental Group 2 has a lower diffusion impedance.

[0075] Cycle life 对照组 ≥Cycle life 实验组2 >Cycle life 实验组1

[0076] The cycle life is mainly related to the adhesion between the first negative electrode active material layer and the second negative electrode active material layer in the negative electrode sheet. After the magnetic field is applied, the adhesion will be affected to a certain extent, and therefore the cycle life will be affected to a certain extent. However, during the proportioning process, the content of the binder in the second negative electrode active material layer can be increased, thereby increasing the adhesion between the first negative electrode active material layer and the second negative electrode active material layer to increase the cycle life and achieve a balance between capacity and cycle life.

[0077] High rate charge / discharge capacity retention 实验组2 >High rate charge / discharge capacity retention 实验组1 >High rate charge / discharge capacity retention 对照组

[0078] By performing a rate test on the battery, the retention rate of the battery capacity under high rate charge and discharge can be obtained. The higher the retention rate, the more it can meet the high rate requirements of the battery. The negative electrode sheet in the embodiment of the present application changes the arrangement of graphite particles through a magnetic field, making it easier for lithium ions to diffuse and better meeting the high rate requirements of the battery.

[0079] To sum up, the battery in the embodiment of the present application applies the negative electrode sheet in the above embodiment, uses a double-layer active material layer, and the first negative electrode active material layer and the second negative electrode active material layer are respectively arranged on the surface of the negative electrode collector; the double-layer active material layer can use a composite active material to meet the needs of the battery, and the first active particles are tilted in the first active material layer and form a first angle with the negative electrode collector to facilitate the diffusion of lithium ions, so that the battery has a higher rate performance, and can solve the problems of high-power discharge and power incompatibility in high-end passenger cars.

[0080] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0081] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0082] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0083] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0084] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0085] The above is only a specific implementation or description of a specific implementation of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A negative electrode sheet, characterized in that: The negative electrode sheet comprises: a negative electrode current collector, a first negative electrode active material layer and a second negative electrode active material layer; The first surface and the second surface of the negative electrode current collector are respectively provided with a first negative electrode active material layer, the first negative electrode active material layer is provided with first active particles, the first active particles are evenly arranged in the first negative electrode active material layer, and a first angle is formed between the first active particles and the first surface; The second negative electrode active material layer is disposed on the surface of the first negative electrode active material layer, and second active particles are disposed in the second negative electrode active material layer; The first surface and the second surface of the negative electrode current collector are two side surfaces in the thickness direction of the negative electrode current collector.

2. The negative electrode sheet according to claim 1, characterized in that: At least a portion of the second active particles in the second negative electrode active material layer is parallel to the first surface of the negative electrode current collector.

3. The negative electrode sheet according to claim 1, characterized in that: The second active particles are evenly arranged in the second negative electrode active material layer, and a second angle is formed between the second active particles and the first surface of the negative electrode current collector.

4. The negative electrode sheet according to claim 3, characterized in that: The first active particles and the second active particles are both diamagnetic materials, the first angle is formed by a magnetic field applied to the first active particles, and the second angle is formed by a magnetic field applied to the second active particles.

5. The negative electrode sheet according to claim 3, characterized in that: The absolute values ​​of the first angle and the second angle are 10°-90°.

6. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The negative electrode current collector includes copper foil.

7. The negative electrode sheet according to any one of claims 1 to 5, characterized in that: The solid phase diffusion coefficient of lithium in the second negative electrode active material layer is greater than the solid phase diffusion coefficient of lithium in the first negative electrode active material layer.

8. A battery, characterized in that: The battery comprises a plurality of battery cells, wherein the battery cells comprise a positive electrode sheet and a negative electrode sheet as claimed in any one of claims 1 to 7, wherein the positive electrode sheet comprises a positive electrode active material layer and a positive electrode current collector.

9. An electrical device, characterized in that: The electrical device comprises the battery according to claim 8.

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