Negative electrode of lithium ion battery, preparation method of negative electrode, lithium ion battery and vehicle

Abstract

The invention relates to a negative electrode of a lithium ion battery, a preparation method of the negative electrode, the lithium ion battery and a vehicle. The negative electrode comprises a negative electrode current collector, a silicon-based negative electrode body and a carbon-based negative electrode body; the negative current collector comprises a plurality of current collecting columns which are crossed in a net shape, and a plurality of grid holes are formed in the negative current collector; at least part of the surfaces of part of the current collecting columns are surrounded and coated by the silicon-based negative electrode body, and at least part of the structure of the carbon-based negative electrode body is filled in the grid holes; a part of the outer surface of the silicon-based negative electrode body is not covered by the carbon-based negative electrode body, and the silicon-based negative electrode body is used for being in direct contact with an electrolyte of the lithium ion battery. The negative electrode, the lithium ion battery and the vehicle have the advantages of high charging rate and high discharging rate.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a negative electrode of a lithium-ion battery and a preparation method thereof, a lithium-ion battery and a vehicle. Background Art

[0002] In the related art, a lithium-ion battery includes a negative electrode, which includes a negative electrode current collector and an active material. During charging, lithium ions are embedded in the active material, and during discharging, lithium ions are de-embedded in the active material. The structure of the negative electrode in the related art has defects, and the charging and discharging rates of the lithium-ion battery are both low. Summary of the invention

[0003] In view of this, the present application provides a negative electrode of a lithium-ion battery and a preparation method thereof, a lithium-ion battery and a vehicle, which have the advantages of high charging rate and high discharging rate.

[0004] In a first aspect, the present application provides a negative electrode of a lithium-ion battery, the negative electrode comprising a negative electrode collector, a silicon-based negative electrode body and a carbon-based negative electrode body, the negative electrode collector comprising a plurality of current collector columns intersecting in a mesh, and the negative electrode collector being provided with a plurality of grid holes, at least a portion of the surface of a portion of the current collector columns being surrounded and coated by the silicon-based negative electrode body, at least a portion of the structure of the carbon-based negative electrode body being filled in the grid holes, a portion of the outer surface of the silicon-based negative electrode body being not covered by the carbon-based negative electrode body, that is to say, the outer surface of the silicon-based negative electrode body being not completely covered by the carbon-based negative electrode body, and the silicon-based negative electrode body being used to be in direct contact with the electrolyte of the lithium-ion battery.

[0005] Since at least part of the surface of a part of the current collector is surrounded and coated by the silicon-based negative electrode body, the conductivity between the negative electrode current collector and the silicon-based negative electrode body can be increased. In detail, when the lithium-ion battery is discharged, the electrons in the various parts of the structure of the silicon-based negative electrode body can be conducted to the current collector nearby (along the shortest path), so that the electrons are quickly conducted to the external circuit through the negative electrode current collector. When the lithium-ion battery is charged, the electrons in the external circuit can be quickly distributed on the contact surface between the current collector and the silicon-based negative electrode body, and more electrons can be simultaneously conducted to the silicon-based negative electrode body in a unit time.

[0006] Since the outer surface of the silicon-based negative electrode body is partially not covered by the carbon-based negative electrode body, and the silicon-based negative electrode body can be used to directly contact the electrolyte. When the lithium-ion battery is charged, the lithium ions of the electrolyte can be directly embedded in the silicon-based negative electrode body, and the rate of lithium ion embedding into the silicon-based negative electrode body is high. When the lithium-ion battery is discharged, the lithium ions deintercalated from the silicon-based negative electrode body can directly migrate to the electrolyte, and the rate of lithium ion deintercalation from the silicon-based negative electrode body is high.

[0007] According to the above content, when the lithium-ion battery is charged, the rate at which the electrons in the external circuit are conducted to the silicon-based negative electrode body through the negative electrode current collector is high, and the rate at which the lithium ions are embedded in the silicon-based negative electrode body is high. Therefore, the charging rate of the lithium-ion battery is high. When the lithium-ion battery is discharged, the rate at which the electrons are conducted from the silicon-based negative electrode body through the negative electrode current collector to the external circuit is high, and the rate at which the lithium ions are deintercalated from the silicon-based negative electrode body is high. Therefore, the discharge rate of the lithium-ion battery is high.

[0008] Optionally, the negative electrode current collector may include at least one of silver metal, copper metal and aluminum metal, so that the negative electrode current collector has high conductivity characteristics.

[0009] Optionally, the negative electrode includes at least two cylindrical current collecting columns and at least two annular silicon-based negative electrode bodies; at least a portion of the structure of the at least two current collecting columns is circumferentially covered by at least one corresponding silicon-based negative electrode body.

[0010] Optionally, the ratio of the inner diameter of the silicon-based negative electrode body to the outer diameter of the silicon-based negative electrode body is in the range of 0.6 to 0.7.

[0011] Optionally, the thickness of the silicon-based negative electrode body is in the range of 15 μm to 20 μm.

[0012] Optionally, the area of ​​the outer surface of the silicon-based negative electrode body that contacts the carbon-based negative electrode body is the first area, and the area of ​​the outer surface of the silicon-based negative electrode body that contacts the electrolyte is the second area; the ratio of the first area to the second area is in the range of 1.5 to 2.5.

[0013] Optionally, the negative electrode current collector includes at least two first negative electrode current collector columns and at least two second negative electrode current collector columns; at least two first negative electrode current collector columns extend along a first direction, at least two second negative electrode current collector columns extend along a second direction, and the first direction intersects with the second direction; at least a portion of the surface of at least one first negative electrode current collector column is circumferentially covered by the silicon-based negative electrode body.

[0014] In a second aspect, the present application provides a method for preparing a negative electrode of a lithium-ion battery, the preparation method comprising: preparing a negative electrode current collector including a plurality of mesh-shaped cross-current collecting columns and provided with a plurality of grid holes, and coating the entire surface of the negative electrode current collector with a silicon-based negative electrode slurry; drying the silicon-based negative electrode slurry to form a prefabricated silicon-based negative electrode body; removing the local structure of the prefabricated silicon-based negative electrode body to form a silicon-based negative electrode body and expose the local structure of the negative electrode current collector; filling the grid holes with a carbon-based negative electrode slurry, and exposing a portion of the outer surface of the silicon-based negative electrode body to the carbon-based negative electrode slurry; and drying the carbon-based negative electrode slurry to form a carbon-based negative electrode body.

[0015] The preparation method of the negative electrode of the lithium-ion battery may also include: providing at least two first negative current collecting columns; coating the first negative current collecting columns with a silicon-based negative electrode slurry; drying the silicon-based negative electrode slurry to form a silicon-based negative electrode body; providing at least two second negative current collecting columns, and making the extension direction of the second negative current collecting columns intersect with the extension direction of the first negative current collecting columns; pressing the first negative current collecting column and the second negative current collecting column to form a negative current collector provided with a plurality of grid holes; filling the grid holes with a carbon-based negative electrode slurry, and making a part of the outer surface of the silicon-based negative electrode body exposed to the carbon-based negative electrode slurry; and drying the carbon-based negative electrode slurry to form a carbon-based negative electrode body.

[0016] The negative electrode prepared according to the preparation method provided in the present application can have the technical effects of the negative electrode described above, which will not be repeated here.

[0017] In a third aspect, the present application provides a lithium-ion battery, the lithium-ion battery comprising the negative electrode described above, or the lithium-ion battery comprising the negative electrode prepared by the method for preparing the negative electrode of the lithium-ion battery described above. Accordingly, the charging rate and the discharging rate of the lithium-ion battery of the present application are both relatively high, which will not be described in detail here.

[0018] In a fourth aspect, the present application provides a vehicle, which includes the lithium-ion battery described above. Accordingly, the vehicle of the present application also includes the advantages of high charging and discharging rates of the lithium-ion battery. The high charging rate makes the charging time of the vehicle relatively short, and the usable rate of the vehicle is high. The high discharge rate enables the lithium-ion battery to better meet the demand for large current output, and the vehicle equipped with the lithium-ion battery can have the advantages of longer endurance, greater acceleration capability, and stronger climbing ability. Therefore, the vehicle of the present application can bring users a better car experience.

[0019] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 Schematic diagram of the winding structure of the negative electrode, separator and positive electrode;

[0022] Figure 2 Schematic diagram of the stacking structure of the negative electrode, the separator and the positive electrode;

[0023] Figure 3 Schematic diagram of the structure of the negative electrode current collector;

[0024] Figure 4 Schematic diagram of the structure of the negative electrode current collector and the silicon-based negative electrode body, wherein the silicon-based negative electrode body covers the first negative electrode current collector column;

[0025] Figure 5 Schematic diagram of the structure of the negative electrode current collector, the silicon-based negative electrode body and the carbon-based negative electrode body;

[0026] Figure 6 for Figure 5 A schematic diagram of the cross-sectional structure along the middle direction AA;

[0027] Figure 7 is a schematic structural diagram of the first negative electrode current collecting column in other embodiments;

[0028] Figure 8 It is a schematic diagram of the structure of the negative electrode current collector and the silicon-based negative electrode body, wherein the prefabricated silicon-based negative electrode body covers the first negative electrode current collector column and the second negative electrode current collector column;

[0029] Fig. 9 A schematic diagram of a structure in which a plurality of first negative electrode current collecting columns are arranged at intervals;

[0030] Fig.10 It is a schematic diagram of a structure in which a plurality of first negative electrode current collecting columns are arranged at intervals, wherein each first negative electrode current collecting column is coated by a corresponding silicon-based negative electrode body;

[0031] Fig.11 The figure is a state diagram of a plurality of first negative electrode current collecting columns and a plurality of second negative electrode current collecting columns before being pressed together, wherein each first negative electrode current collecting column is coated by a corresponding silicon-based negative electrode body.

[0032] Reference numerals:

[0033] 1- negative electrode;

[0034] 11- negative electrode current collector;

[0035] 11a-grid holes;

[0036] 111 - a first negative electrode current collecting column;

[0037] 111a-1st paragraph;

[0038] 111b-Second paragraph;

[0039] 112 - a second negative electrode current collecting column;

[0040] 12-silicon-based negative electrode;

[0041] 12a-prefabricated silicon-based negative electrode body;

[0042] 13-carbon-based negative electrode;

[0043] 2- diaphragm;

[0044] 3- Positive electrode. DETAILED DESCRIPTION

[0045] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0046] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0047] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0048] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0049] In the first aspect, the present invention provides a negative electrode of a lithium-ion battery. For ease of understanding, this article first describes the structure and principle of the lithium-ion battery, and then specifically introduces the structure and technical effects of the negative electrode provided by the present invention.

[0050] It should be noted that a lithium-ion battery is a secondary battery, and other names for secondary batteries include rechargeable batteries or storage batteries. Among them, a lithium-ion battery may include a negative electrode, a separator, a positive electrode, and an electrolyte.

[0051] like Figure 1 As shown, the negative electrode 1 (indicated by a thick solid line), the separator 2 (indicated by a dotted line) and the positive electrode 3 (indicated by a thin solid line) can be wound and arranged, and accordingly, the negative electrode 1 (indicated by a thick solid line), the separator 2 (indicated by a dotted line) and the positive electrode 3 (indicated by a thin solid line) can be wound and arranged. Figure 1 The lithium-ion battery of the structure shown can be called a wound lithium-ion battery. Figure 2 As shown, the negative electrode 1, the separator 2 and the positive electrode 3 can also be stacked, including Figure 2The lithium-ion battery of the structure shown can be referred to as a stacked lithium-ion battery. Regardless of the winding arrangement or the stacking arrangement, the negative electrode 1 and the positive electrode 3 need to be separated by a diaphragm 2. The diaphragm 2 is a poor conductor of electrons, that is, the diaphragm 2 can be used to prevent electrons from being transmitted between the negative electrode 1 and the positive electrode 3, reduce the possibility of short circuit problems between the negative electrode 1 and the positive electrode 3, and then reduce the possibility of explosion of the lithium-ion battery. However, the diaphragm 2 has micropores (micrometer level) in it, and the micropores can contain electrolytes. The electrolyte is a medium for the migration of lithium ions. The diaphragm 2 can allow lithium ions to migrate between the negative electrode 1 and the positive electrode 3 through the electrolyte.

[0052] When the lithium-ion battery is charged by an external circuit, lithium ions are deintercalated from the positive electrode 3, and the deintercalated lithium ions migrate to the negative electrode 1 through the electrolyte. The lithium ions are then intercalated into the negative electrode 1, and the electrons of the external circuit are conducted to the negative electrode 1. The negative electrode 1 changes from a lithium-deficient state to a lithium-rich state, and the positive electrode 3 changes from a lithium-rich state to a lithium-deficient state.

[0053] When the lithium-ion battery discharges to an external circuit, lithium ions are deintercalated from the negative electrode 1, and the deintercalated lithium ions migrate to the positive electrode 3 through the electrolyte. The lithium ions are then intercalated into the positive electrode 3, and the electrons of the negative electrode 1 are conducted to the external circuit. The negative electrode 1 changes from a lithium-rich state to a lithium-poor state, and the positive electrode 3 changes from a lithium-poor state to a lithium-rich state.

[0054] It should be noted that the negative electrode and the positive electrode described herein are electrodes including active materials, and lithium ions can be embedded in the active materials, and of course lithium ions can also be deintercalated from the active materials. In this article, the structure used to electrically connect the external circuit and the negative electrode in the lithium-ion battery can be described as the negative terminal, and the structure used to electrically connect the external circuit and the positive electrode in the lithium-ion battery can be described as the positive terminal.

[0055] The following content of this article mainly introduces the structure and technical effects of the negative electrode of lithium-ion batteries.

[0056] In some embodiments, the negative electrode includes a negative electrode current collector, a silicon-based negative electrode body, and a carbon-based negative electrode body.

[0057] The negative electrode current collector is used to be electrically connected to an external circuit so that electrons can be conducted between the negative electrode current collector and the external circuit. In detail, the negative electrode current collector can be electrically connected to the external circuit indirectly through the negative terminal. In other embodiments, the electrical connection between the negative electrode current collector and the external circuit can also be directly electrically connected.

[0058] The silicon-based negative electrode body and the carbon-based negative electrode body are both active materials for realizing the charging of lithium-ion batteries and the active materials for realizing the discharging of lithium-ion batteries.

[0059] When a lithium-ion battery is charged, the lithium ions in the electrolyte can be embedded in the silicon-based negative electrode body and the carbon-based negative electrode body, and the electrons are conducted from the external circuit to the negative electrode current collector. The lithium ions embedded in the silicon-based negative electrode body and the lithium ions embedded in the carbon-based negative electrode body undergo a reduction reaction after obtaining the electrons. When the lithium-ion battery is discharged, an oxidation reaction occurs, and the lithium ions are de-embedded in the silicon-based negative electrode body and the carbon-based negative electrode body. The de-embedded lithium ions enter the electrolyte, and the electrons located in the silicon-based negative electrode body and the electrons located in the carbon-based negative electrode body can be conducted to the external circuit through the negative electrode current collector.

[0060] The negative electrode current collector includes a metal, and the conductivity of the negative electrode current collector is higher than that of the silicon-based negative electrode body and the carbon-based negative electrode body. When the lithium-ion battery is discharged, the negative electrode current collector can quickly collect electrons from the silicon-based negative electrode body and the carbon-based negative electrode body, and the electrons can be quickly conducted to the external circuit. When the lithium-ion battery is charged, electrons can be quickly conducted from the external circuit to the silicon-based negative electrode body and the carbon-based negative electrode body through the negative electrode current collector.

[0061] It should be noted that the carbon-based negative electrode has the following advantages: the conductivity of the carbon-based negative electrode is better than that of the silicon-based negative electrode, and the carbon-based negative electrode exhibits a relatively low and flat potential characteristic during the process of being embedded with lithium ions, which makes the operating voltage of the lithium-ion battery relatively high and stable, and makes the lithium-ion battery safer and more stable and has a relatively longer service life.

[0062] It should be noted that silicon-based negative electrodes have the following advantages: the theoretical embeddable lithium ion capacity of silicon-based negative electrodes is higher than that of carbon-based negative electrodes, and the specific capacity of lithium-ion batteries with silicon-based negative electrodes is relatively high, so that the theoretical specific capacity of lithium-ion batteries can be as high as 4200mAh / g.

[0063] According to the above content, the negative electrode in some embodiments has the advantages of both silicon-based negative electrode bodies and carbon-based negative electrode bodies, so that the lithium-ion battery has the advantages of high specific capacity, high voltage, high safety and stability, and long service life.

[0064] In some embodiments, please refer to Figure 3 As shown, the negative electrode current collector 11 includes a plurality of mesh-shaped cross-current collecting columns (eg, a first negative electrode current collector column 111 and a second negative electrode current collector column 112), and the negative electrode current collector 11 is provided with a plurality of mesh holes 11a. Figure 4 As shown, at least a portion of the surface of a portion of the current collectors (eg, the first negative current collector 111) is surrounded and covered by the silicon-based negative electrode body 12. Figure 5 As shown, at least a portion of the carbon-based negative electrode body 13 fills the grid holes (not shown in the figure), and accordingly, the carbon-based negative electrode body 13 also contacts at least a portion of the surface of a number of current collecting columns (such as the second negative current collecting column 112).

[0065] It should be noted that in the drawings herein, directions X, Y and Z are perpendicular to each other, wherein direction Z represents the thickness direction of the negative electrode 1 .

[0066] When the lithium-ion battery is charged, the electrons of the external circuit can be conducted to the silicon-based negative electrode body 12 through a plurality of mesh-shaped cross-current collecting columns, and the electrons of the external circuit can also be conducted to the carbon-based negative electrode body 13 through a plurality of mesh-shaped cross-current collecting columns, and the lithium ions embedded in the silicon-based negative electrode body 12 and the lithium ions embedded in the carbon-based negative electrode body 13 undergo a reduction reaction after obtaining the electrons. When the lithium-ion battery is discharged, an oxidation reaction occurs, and the lithium ions are deintercalated from the silicon-based negative electrode body 12 and the carbon-based negative electrode body 13. The deintercalated lithium ions enter the electrolyte, and the electrons located in the silicon-based negative electrode body 12 and the electrons located in the carbon-based negative electrode body 13 are both conducted to the external circuit through a plurality of mesh-shaped cross-current collecting columns.

[0067] Since at least part of the surface of a part of the current collectors (e.g., the first negative current collectors 111) is surrounded and covered by the silicon-based negative electrode body 12, the contact area between the current collectors and the silicon-based negative electrode body 12 is relatively large, which can improve the conductivity between the current collectors and the silicon-based negative electrode body 12, and accordingly, the conductivity between the negative current collector 11 and the silicon-based negative electrode body 12 can be improved. In detail, when the lithium-ion battery is discharged, the electrons in the various parts of the structure of the silicon-based negative electrode body 12 can be conducted to the current collectors (e.g., the first negative current collectors 111) nearby (along the shortest path), so that the electrons are quickly conducted to the external circuit through the negative current collector 11, and when the lithium-ion battery is charged, the electrons of the external circuit can be quickly distributed on the contact surface between the current collectors (e.g., the first negative current collectors 111) and the silicon-based negative electrode body 12, and more electrons can be simultaneously conducted to the silicon-based negative electrode body 12 per unit time.

[0068] In some embodiments, a portion of the outer surface of the silicon-based negative electrode body 12 is not covered by the carbon-based negative electrode body 13, and the silicon-based negative electrode body 12 can be directly in contact with the electrolyte. When the lithium-ion battery is charged, the lithium ions of the electrolyte can be directly embedded in the silicon-based negative electrode body 12, and the rate of lithium ion embedding in the silicon-based negative electrode body 12 is high. When the lithium-ion battery is discharged, the lithium ions deintercalated from the silicon-based negative electrode body 12 can directly migrate to the electrolyte, and the rate of lithium ions deintercalating from the silicon-based negative electrode body 12 is high.

[0069] According to the above content, when the lithium-ion battery is charged, the rate at which the electrons in the external circuit are conducted to the silicon-based negative electrode body 12 through the negative electrode current collector 11 is high, and the rate at which the lithium ions are embedded in the silicon-based negative electrode body 12 is high, so the charging rate of the lithium-ion battery is high. When the lithium-ion battery is discharged, the rate at which the electrons are conducted from the silicon-based negative electrode body 12 through the negative electrode current collector 11 to the external circuit is high, and the rate at which the lithium ions are deintercalated from the silicon-based negative electrode body 12 is high, so the discharge rate of the lithium-ion battery is high.

[0070] Since at least part of the surface of a part of the current collector columns (e.g., the first negative current collector column 111) is surrounded and covered by the silicon-based negative electrode body 12, even if the silicon-based negative electrode body 12 expands when lithium ions are embedded and shrinks when lithium ions are extracted, the forces borne by the parts of the outer surface of the current collector column surrounded and covered by the silicon-based negative electrode body 12 are the same or almost the same, that is, the combined force borne by the outer surface of the current collector column surrounded and covered by the silicon-based negative electrode body 12 is relatively small, and the current collector column surrounded and covered by the silicon-based negative electrode body 12 is not easy to produce large bending deformation, and the current collector column surrounded and covered by the silicon-based negative electrode body 12 is not easy to break. Even after multiple charging and discharging, the current collector column surrounded and covered by the silicon-based negative electrode body 12 is not easy to reach the limit of fatigue damage.

[0071] Since at least part of the surface of a part of the current collecting columns (for example, the first negative current collecting column 111) is surrounded and covered by the silicon-based negative electrode body 12, the potential distribution, current density distribution and heat distribution of each part within the silicon-based negative electrode body 12 can be relatively uniform in the annular direction, which can effectively reduce the aging rate of the silicon-based negative electrode body 12.

[0072] Since the expansion amplitude of the carbon-based negative electrode body 13 when embedded with lithium ions is smaller than that of the silicon-based negative electrode body 12 when embedded with lithium ions, and the contraction amplitude of the carbon-based negative electrode body 13 when de-embedded with lithium ions is smaller than that of the silicon-based negative electrode body 12 when de-embedded with lithium ions. Therefore, in some embodiments, at least part of the carbon-based negative electrode body 13 is filled in the mesh holes 11a, and accordingly, the expansion amplitude and contraction amplitude of the part of the carbon-based negative electrode body 13 in the mesh holes 11a are both smaller, and the force exerted by the part of the carbon-based negative electrode body 13 in the mesh holes 11a on the current collecting column and the silicon-based negative electrode body 12 located around the mesh holes 11a is relatively small, so the current collecting column and the silicon-based negative electrode body 12 located around the mesh holes 11a are not easily squeezed, deformed or broken.

[0073] According to the above content, it can be known that the service life of the negative electrode 1 is relatively long, and accordingly, the service life of the lithium ion battery is also relatively long.

[0074] Please refer to Figure 5-Figure 6As shown, the carbon-based negative electrode body 13 can contact with multiple second negative electrode current collectors 112, and the contact area between the carbon-based negative electrode body 13 and the multiple second negative electrode current collectors 112 is relatively large, and the conductivity between the carbon-based negative electrode body 13 and the multiple second negative electrode current collectors 112 is relatively high. Correspondingly, the conductivity between the carbon-based negative electrode body 13 and the negative electrode current collector 11 is relatively high. In detail, the local structure of the carbon-based negative electrode body 13 may increase the resistivity of the local structure of the carbon-based negative electrode body 13 due to the embedding of lithium ions, and the local structure of the carbon-based negative electrode body 13 may have a dead area that is difficult to conduct electrons, and the dead area will hinder the conduction of electrons in other areas. Since the contact area between the carbon-based negative electrode body 13 and the plurality of second negative electrode current collectors 112 is relatively large, when the lithium-ion battery is discharged, the electrons in the various structures in the carbon-based negative electrode body 13 can be conducted to the second negative electrode current collector 112 nearby (along the shortest path), so that the electrons are quickly conducted to the external circuit through the negative electrode current collector 11, and when the lithium-ion battery is charged, the electrons in the external circuit can be quickly distributed on the contact surface between the second negative electrode current collector 112 and the carbon-based negative electrode body 13, and more electrons can be simultaneously conducted to the carbon-based negative electrode body 13 per unit time. According to the above content, the arrangement of the negative electrode current collector including a plurality of mesh-shaped cross-current collectors allows the electrons to bypass the dead zone of the local structure in the carbon-based negative electrode body 13, so that the conductivity between the negative electrode current collector 11 and the carbon-based negative electrode body 13 is high, thereby making the charging rate and the discharging rate of the lithium-ion battery high.

[0075] It should be noted that the cross-section of each current collector column along the direction perpendicular to its own extension direction may include a circular, elliptical, rectangular or other polygonal shape. Correspondingly, the cross-section of the silicon-based negative electrode body surrounding and covering the current collector column along the direction perpendicular to its own extension direction may include a circular ring, an elliptical ring, a rectangular ring or other closed ring shape.

[0076] Optionally, see Figure 5 As shown, the negative electrode 1 includes at least two cylindrical current collectors (e.g., the first negative current collector 111 and / or the second negative current collector 112) and at least two annular silicon-based negative electrode bodies 12. At least part of the structure of the at least two current collectors (e.g., the first negative current collector 111) is circumferentially covered (surrounded in the circumferential direction) by at least one corresponding silicon-based negative electrode body 12.

[0077] It should be noted that in the related art, when the lithium-ion battery is charged, the embedding of lithium ions into the silicon-based negative electrode body causes the silicon-based negative electrode body to expand and generate stress, and when the lithium-ion battery is discharged, the deintercalation of lithium ions into the silicon-based negative electrode body causes the silicon-based negative electrode body to shrink and generate stress. In some embodiments provided in the present application, both the outer surface and the inner surface of the annular silicon-based negative electrode body 12 may include arc surfaces, and the stress concentration of the arc surfaces is low. Both the outer surface and the inner surface of the silicon-based negative electrode body 12 are not easy to break, and it is not easy to increase the interface impedance of the silicon-based negative electrode body 12, so that the lithium-ion battery can maintain a relatively high charging rate and discharging rate. Correspondingly, the outer surface of the current collector column (e.g., the first negative current collector column 111) circumferentially covered by the silicon-based negative electrode body 12 also includes an arc surface, and the component forces borne by each part of the outer surface of the current collector column circumferentially covered by the silicon-based negative electrode body 12 are the same or almost the same, and the combined force borne by the outer surface of the current collector column circumferentially covered by the silicon-based negative electrode body 12 is relatively small, and the current collector column circumferentially covered by the silicon-based negative electrode body 12 is not prone to large bending deformation, and the current collector column circumferentially covered by the silicon-based negative electrode body 12 is not prone to fracture. Even after multiple charging and discharging, the current collector column circumferentially covered by the silicon-based negative electrode body 12 is not prone to reach the limit of fatigue damage.

[0078] Please refer to Figure 5 As shown, each first negative electrode current collector column 111 is circumferentially covered by a corresponding annular silicon-based negative electrode body 12 .

[0079] In other embodiments (not shown in the figures), the same first negative current collector column is circumferentially covered by two or more annular silicon-based negative electrode bodies, and these annular silicon-based negative electrode bodies can be spaced apart in the extension direction of the same first negative current collector column.

[0080] In other embodiments (not shown in the figure), the second negative electrode current collecting columns may be circumferentially covered by a corresponding annular silicon-based negative electrode body.

[0081] In other embodiments (not shown in the figures), a partial structure of the first negative electrode current collector column may be circumferentially covered by the corresponding annular silicon-based negative electrode body, and at the same time, a partial structure of the second negative electrode current collector column may be circumferentially covered by the corresponding annular silicon-based negative electrode body.

[0082] The subsequent content of this article is mainly described by taking "each first negative electrode current collector column is circumferentially covered by a corresponding annular silicon-based negative electrode body" as an example.

[0083] It should be noted that in the relevant technology, when the lithium-ion battery is charged, a lithium compound film (SEI film) will be formed on the surface of the silicon-based negative electrode. After the thickness of the lithium compound film reaches a certain size, the excessively thick lithium compound film will prevent the lithium ions from continuing to embed into the silicon-based negative electrode. If a relatively large block of silicon-based negative electrode is used to embed lithium ions, most of the silicon-based negative electrode is not embedded with lithium ions. It can also be said that most of the silicon-based negative electrode is not effectively utilized.

[0084] Optionally, see Figure 6 As shown, the ratio of the inner diameter D1 of the silicon-based negative electrode body 12 to the outer diameter D2 of the silicon-based negative electrode body 12 is in the range of 0.6 to 0.7. Among them, the ratio can be specifically 0.6, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69 or 0.7. If the ratio is less than 0.6, the thickness of the annular silicon-based negative electrode body 12 is too large, or it can be said that the annular silicon-based negative electrode body 12 is too thick, and there are more parts of the silicon-based negative electrode body 12 that cannot be used to embed lithium ions, that is, there are fewer parts of the silicon-based negative electrode body 12 that can be effectively utilized. If the ratio is greater than 0.7, the thickness of the annular silicon-based negative electrode body 12 is too small, or it can be said that the annular silicon-based negative electrode body 12 is too thin, and the capacity of the silicon-based negative electrode body 12 that can embed lithium ions is too small. Therefore, the ratio is preferably in the range of 0.6 to 0.7.

[0085] Please refer to Figure 6 As shown, in the same grid hole (not marked in the figure), the silicon-based negative electrode body 12 is located on both sides of the carbon-based negative electrode body 13 close to the first negative electrode current collector 111, and the size of the silicon-based negative electrode body 12 in the direction Y is smaller than the size of the carbon-based negative electrode body 13 in the direction Y. Under this setting, the part of the silicon-based negative electrode body 12 that cannot be effectively used to embed lithium ions is relatively small, and the space saved in the grid hole can be used to accommodate more carbon-based negative electrode bodies 13, so that the negative electrode can effectively embed more lithium ions.

[0086] Optionally, see Figure 6 As shown, the thickness of the silicon-based negative electrode body 12 (half of the difference between the outer diameter D2 and the inner diameter D1) is in the range of 15μm to 20μm. Among them, the thickness of the silicon-based negative electrode body 12 can specifically be 15μm, 16μm, 17μm, 18μm, 19μm or 20μm. If the thickness is greater than 20μm, the thickness dimension of the silicon-based negative electrode body 12 is too large, the silicon-based negative electrode body 12 is too thick, and there are more parts of the silicon-based negative electrode body 12 that cannot be used to embed lithium ions, that is, there are fewer parts of the silicon-based negative electrode body 12 that can be effectively utilized. If the thickness is less than 15μm, the thickness dimension of the silicon-based negative electrode body 12 is too small, the silicon-based negative electrode body 12 is too thin, and the capacity of the silicon-based negative electrode body 12 that can embed lithium ions is too small. Therefore, it is better that the thickness of the silicon-based negative electrode body 12 is in the range of 15μm to 20μm.

[0087] Optionally, see Figure 6 As shown, the inner diameter D1 of the silicon-based negative electrode body 12 ranges from 75μm to 85μm, and the inner diameter D1 of the silicon-based negative electrode body 12 can specifically be 75μm, 76μm, 77μm, 78μm, 79μm, 80μm, 81μm, 82μm, 83μm, 84μm or 85μm.

[0088] The inner diameter D1 of the silicon-based negative electrode body 12 may also be regarded as the diameter of the current collecting column (eg, the first negative electrode current collecting column 111 ) circumferentially covered by the silicon-based negative electrode body 12 .

[0089] In addition, the diameter of the second negative current collecting column 112 may be the same as the diameter of the first negative current collecting column 111 , or the diameter of the second negative current collecting column 112 may be different from the diameter of the first negative current collecting column 111 .

[0090] Optionally, see Figure 6 As shown, the outer diameter D2 of the silicon-based negative electrode body 12 ranges from 115μm to 125μm, and the outer diameter D2 of the silicon-based negative electrode body 12 can specifically be 115μm, 116μm, 117μm, 118μm, 119μm, 120μm, 121μm, 122μm, 123μm, 124μm or 125μm.

[0091] Optionally, see Figure 6 As shown, the thickness (dimension along direction Z) of the carbon-based negative electrode body 13 is smaller than the outer diameter D2 of the silicon-based negative electrode body 12, and the thickness (dimension along direction Z) of the carbon-based negative electrode body 13 is greater than the inner diameter D1, and the thickness of the carbon-based negative electrode body 13 is greater than the thickness (dimension along direction Z) of the negative electrode collector 11.

[0092] Optionally, see Figure 6As shown, the area of ​​the portion of the outer surface of the silicon-based negative electrode body 12 that contacts the carbon-based negative electrode body 13 is the first area, and the area of ​​the portion of the outer surface of the silicon-based negative electrode body 12 that contacts the electrolyte (not shown in the figure) is the second area. It should be noted that the area of ​​the portion of the outer surface of the silicon-based negative electrode body 12 that is not covered by the carbon-based negative electrode body 13 may also be the second area. The ratio of the first area to the second area is in the range of 1.5 to 2.5. The ratio can specifically be 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4 or 2.5. If the ratio is less than 1.5, the second area is too large, and the number of dangling bonds in contact with the electrolyte on the surface of the silicon-based negative electrode body 12 is too large, which is more likely to cause more electrolyte decomposition. If the ratio is greater than 2.5, the second area is too small, and the rate at which lithium ions in the electrolyte are directly embedded in the silicon-based negative electrode body 12 is low, that is, the charging rate is low. Of course, the rate at which lithium ions are directly deintercalated from the silicon-based negative electrode body 12 and enter the electrolyte is low, that is, the discharge rate is low. Therefore, the ratio is preferably within the range of 1.5 to 2.5.

[0093] It should be noted that the definition of a dangling bond is: because the crystal lattice terminates at the surface, each atom in the outermost layer of the surface has an unpaired electron, that is, there is an unsaturated chemical bond.

[0094] Optionally, see Figure 3 As shown, the negative electrode current collector 11 includes at least two first negative electrode current collectors 111 and at least two second negative electrode current collectors 112, at least two first negative electrode current collectors extend along a first direction, at least two second negative electrode current collectors 112 extend along a second direction, and the first direction intersects the second direction. In detail, the first direction and the second direction may be perpendicular, for example, the first direction is parallel to the direction X, and the second direction is parallel to the direction Y. Alternatively, the first direction is not perpendicular to the second direction, but the first direction is not parallel to the second direction either.

[0095] In other embodiments (not shown in the figures), the negative electrode current collector may further include at least two third negative electrode current collecting columns, and the at least two third negative electrode current collecting columns extend along the third direction, and each two directions in the first direction, the second direction and the third direction are neither perpendicular nor parallel.

[0096] The following content of this article mainly describes the negative electrode current collector by taking "the negative electrode current collector includes at least two first negative electrode current collecting columns and at least two second negative electrode current collecting columns, and the first negative electrode current collecting columns and the second negative electrode current collecting columns are perpendicular" as an example.

[0097] In other embodiments, please refer to Figure 7As shown, the first negative electrode current collector 111 may also include at least two first segments 111a and at least two second segments 111b, the first segments 111a and the second segments 111b are alternately connected along the extension direction of the first negative electrode current collector 111 (the direction parallel to the direction X), the first segment 111a and the second segment 111b both include a cylindrical structure, and the diameter of the first segment 111a may be smaller than the diameter of the second segment 111b. Under this setting, on the one hand, the conductive area of ​​the first negative electrode current collector 111 is relatively large, and it has the advantage of a high conductivity rate. On the other hand, the structure of the first negative electrode current collector 111 can be limitedly connected to the silicon-based negative electrode body (not shown in the figure), and the limited connection can better limit the movement of the silicon-based negative electrode body relative to the first negative electrode current collector 111 along the extension direction of the first negative electrode current collector 111. In other words, the first negative electrode current collector 111 can better limit the expansion of the silicon-based negative electrode body along the extension direction of the first negative electrode current collector 111 during charging, and the first negative electrode current collector 111 can also better limit the contraction of the silicon-based negative electrode body along the extension direction of the first negative electrode current collector 111 during discharge. Therefore, the structural stability of the negative electrode is better, the lithium-ion battery has higher safety stability, and the lithium-ion battery has a longer service life.

[0098] In other embodiments, the shape of the second negative electrode current collecting column may also be similar to Figure 7 If the second negative electrode current collector includes alternatingly connected structural segments with different diameters, the second negative electrode current collector can also better limit the expansion and contraction of the carbon-based negative electrode body along the extension direction of the second negative electrode current collector, so the structural stability of the negative electrode is better, the lithium-ion battery has higher safety stability, and the lithium-ion battery has a longer service life.

[0099] Optionally, see Figure 3 As shown, the first negative electrode current collecting column 111 and the second negative electrode current collecting column 112 are integrally connected. In detail, the integrally connected first negative electrode current collecting column 111 and the second negative electrode current collecting column 112 can be realized by casting, welding or 3D printing.

[0100] Of course, the first negative electrode current collector and the second negative electrode current collector can also be connected by pressing or braiding. In detail, a plurality of arranged first negative electrode current collectors and a plurality of arranged second negative electrode current collectors can be pressed together by a press, and a plurality of first negative electrode current collectors and a plurality of second negative electrode current collectors can also be braided together by a braiding machine.

[0101] Optionally, see Figure 3 As shown, the mesh number of the negative electrode current collector 11 is within the unit of 400 mesh to 1000 mesh, and the mesh number can be specifically 400, 500, 600, 700, 800, 900 or 1000. The mesh number is defined as the number of mesh holes per unit area.

[0102] Optionally, the material of the negative electrode current collector includes at least one of silver, copper and aluminum. Among them, the conductivity of silver is relatively high, and the conductivity of the negative electrode current collector with silver is relatively high, and the charging rate and discharge rate of the lithium-ion battery are both high. Of course, both copper and aluminum can meet the conductivity requirements of the negative electrode current collector, wherein the conductivity of aluminum is lower than that of copper, and the conductivity of copper is lower than that of silver.

[0103] Optionally, the material of the silicon-based negative electrode body includes at least one of silicon, silicon oxide, silicon-carbon composite material and silicon alloy.

[0104] Among them, silicon may include at least one of single crystal silicon, polycrystalline silicon and amorphous silicon. Silicon oxide may include at least one of silicon oxide (SiO) and silicon oxide (SiO2). Silicon carbon composite material may include silicon carbide. Silicon alloy may include alloying material of silicon and other metal elements (such as tin, aluminum, magnesium, etc.).

[0105] Optionally, the material of the carbon-based negative electrode body includes at least one of natural graphite, artificial graphite, modified graphite, easily graphitized material and hardly graphitized material.

[0106] Optionally, the negative electrode also includes a negative electrode ear (not shown in the figure), which is welded or integrally formed with the negative electrode current collector, and is used to conduct electrons from the negative electrode current collector to an external circuit, or the negative electrode ear is used to conduct electrons from the external circuit to the negative electrode current collector.

[0107] In a second aspect, the present application provides a method for preparing a negative electrode of a lithium-ion battery. In some embodiments, the preparation method may include the following contents:

[0108] Prepared as Figure 3 The negative electrode current collector 11 shown in FIG. 1 includes a plurality of mesh-shaped cross-current collecting columns and is provided with a plurality of grid holes 11a. The entire surface of the negative electrode current collector 11 is coated with a silicon-based negative electrode slurry, and the silicon-based negative electrode slurry is dried to form a negative electrode slurry as shown in FIG. Figure 8 The prefabricated silicon-based negative electrode body 12a shown in FIG. 1 is a prefabricated silicon-based negative electrode body 12a, and a local structure of the prefabricated silicon-based negative electrode body 12a is removed to form a Figure 4 The silicon-based negative electrode body 12 is shown and the local structure of the negative electrode collector 11 is exposed (for example, the second negative electrode collector column 112 is not surrounded and covered by the silicon-based negative electrode body 12), the carbon-based negative electrode slurry is filled in the grid holes, and the outer surface of the silicon-based negative electrode body 12 is partially exposed to the carbon-based negative electrode slurry, and the carbon-based negative electrode slurry is dried to form a Figure 5-Figure 6 The carbon-based negative electrode body 13 shown in FIG. Figure 5-Figure 6 The negative electrode 1 is shown.

[0109] It should be noted that the method of applying the silicon-based negative electrode slurry may include brushing or spraying, etc. Filling the carbon-based negative electrode slurry may include brushing or spraying, etc., but when filling the carbon-based negative electrode slurry, the negative electrode current collector needs to be placed on a stage or a plate so that the carbon-based negative electrode slurry in the grid holes can be well supported before being solidified.

[0110] The method of removing the local structure of the prefabricated silicon-based negative electrode body 12a may include the following:

[0111] Method 1): Use laser to remove Figure 8 The partial structure of the prefabricated silicon-based negative electrode body 12a is shown to form a Figure 4 The silicon-based negative electrode body 12 shown is disposed around and covers a local structure of the negative electrode current collector 11 (eg, the first negative electrode current collecting column 111 ).

[0112] Method 2): In Figure 8 The surface of the prefabricated silicon-based negative electrode body 12a is coated with photoresist, and the local structure of the photoresist is exposed to ultraviolet light, and the properties of the exposed part change, for example, the exposed part is easily removed by the developer, while the unexposed part is not easily removed by the developer, or, for example, the exposed part is not easily removed by the developer, while the unexposed part is easily removed by the developer. After development, the remaining part of the photoresist is dried to form a patterned mask layer (not shown in the figure), which can mask the following: Figure 8 The local structure of the prefabricated silicon-based negative electrode body 12a is shown. After forming the patterned mask layer, the acid solution is used to remove the Figure 8 The portion of the prefabricated silicon-based cathode body 12a not masked by the patterned mask layer and the portion of the prefabricated silicon-based cathode body 12a masked by the patterned mask layer will not be corroded by the acid solution to form a Figure 4 The silicon-based negative electrode body 12 is shown to surround and cover the local structure (such as the first negative current collecting column 111) of the negative electrode current collector 11. Thereafter, the patterned mask layer may be removed by an organic solvent or laser.

[0113] Method 3): Using laser irradiation Figure 8The local structure of the prefabricated silicon-based negative electrode body 12a shown is modified so that the local structure of the prefabricated silicon-based negative electrode body 12a is modified, or in other words, multiple micrometer-sized holes can be formed in the local structure of the prefabricated silicon-based negative electrode body 12a, and then corroded by acid. Since the part of the prefabricated silicon-based negative electrode body 12a with micrometer-sized holes is more easily entered by acid, the part of the prefabricated silicon-based negative electrode body 12a with micrometer-sized holes is corroded by acid at a higher rate, while the part of the prefabricated silicon-based negative electrode body 12a without micrometer-sized holes is not easily entered by acid, and the part of the prefabricated silicon-based negative electrode body 12a without micrometer-sized holes is corroded by acid at a lower rate. Therefore, this method can achieve the selective removal of Figure 8 The local structure of the prefabricated silicon-based negative electrode body 12a is shown, thereby forming Figure 4 The silicon-based negative electrode body 12 shown covers a local structure of the negative electrode current collector 11 (eg, the first negative electrode current collecting column 111 ).

[0114] In other embodiments, the preparation method may include the following:

[0115] Provide as Fig. 9 At least two first negative electrode current collecting columns 111 are shown, and a silicon-based negative electrode slurry is coated on the first negative electrode current collecting column 111, and the silicon-based negative electrode slurry is dried to form a Fig.10 The silicon-based negative electrode body 12 shown in the figure surrounds and covers each first negative electrode current collecting column 111, and provides at least two Fig.11 The second negative electrode current collecting column 112 is formed, and the extension direction of the second negative electrode current collecting column 112 is intersected with the extension direction of the first negative electrode current collecting column 111, and the first negative electrode current collecting column 111 and the second negative electrode current collecting column 112 are pressed together to form a Figure 4 The negative electrode current collector 11 is provided with a plurality of grid holes, and the grid holes are filled with carbon-based negative electrode slurry, and the outer surface of the silicon-based negative electrode body 12 is partially exposed to the carbon-based negative electrode slurry. In other words, the carbon-based negative electrode slurry is not completely covered with the silicon-based negative electrode body 12, and the carbon-based negative electrode slurry is dried to form a Figure 5-Figure 6 The carbon-based negative electrode body 13 shown in FIG. Figure 5-Figure 6 The negative electrode 1 is shown.

[0116] It should be noted that during the pressing process, the portion of the silicon-based negative electrode body located at the cross-connection portion between the first negative current collector column and the second negative current collector column is crushed, and the volume of the crushed portion can be ignored, that is, it does not affect the need for the remaining portion of the silicon-based negative electrode body to surround and cover the first negative current collector column.

[0117] In a third aspect, an embodiment of the present application provides a lithium-ion battery, the lithium-ion battery includes the negative electrode described above, or the lithium-ion battery includes the negative electrode prepared according to the preparation method described above. The lithium-ion battery also includes the separator described above, the positive electrode and the electrolyte. The specific structure, principle and technical effect of the lithium-ion battery have been described above and will not be repeated here.

[0118] Alternatively, the separator may comprise polyethylene (PE) and / or polypropylene (PP).

[0119] Alternatively, the positive electrode may include materials such as lithium cobalt oxide (LCO), lithium nickel cobalt manganese oxide (NCM), lithium iron phosphate (LFP), or lithium manganese oxide (LMO).

[0120] Alternatively, the electrolyte may include a liquid electrolyte and / or a solid electrolyte.

[0121] Optionally, the liquid electrolyte includes an organic solvent and a lithium salt, the organic solvent may include ethylene carbonate (EC), diethyl carbonate (DEC) or dimethyl carbonate (DMC), and the lithium salt may include lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6) or lithium trifluoromethanesulfonate (LiCF3SO3).

[0122] Alternatively, the solid-state electrolyte may include lithium oxide phosphate, lithium oxide silicate, or lithium sulfide phosphate.

[0123] Optionally, the lithium-ion battery further comprises a casing, which is used to accommodate the negative electrode, separator, positive electrode and electrolyte mentioned above.

[0124] Optionally, the lithium-ion battery further includes a positive terminal and a negative terminal, the positive terminal and the negative terminal are disposed in the outer shell, the positive terminal is electrically connected to the positive electrode, the negative terminal is electrically connected to the negative electrode, and the positive terminal and the negative terminal can be used to be electrically connected to an external circuit.

[0125] It should be noted that the external circuit mentioned in this article refers to a circuit other than a lithium-ion battery. The external circuit can be electrically connected to the positive electrode (at least including the positive electrode) and the negative electrode (at least including the negative electrode) of the lithium-ion battery, and a load for converting electrical energy into other energy is provided on the external circuit.

[0126] It should be noted that the electrical connection mentioned in this article refers to the conductive relationship between two conductive materials. The two conductive materials can be in direct physical contact and conduct electricity, or the two conductive materials can be in indirect physical contact and conduct electricity through other conductive materials.

[0127] It should be noted that the lithium-ion batteries mentioned above can be used in vehicles, ships, aircraft, electronic equipment or energy storage equipment.

[0128] In a fourth aspect, an embodiment of the present application provides a vehicle, which may include the lithium-ion battery described above.

[0129] Lithium-ion batteries are used to provide electrical energy to vehicles, which is required by the vehicle's electronic equipment, lighting equipment, power equipment and other energy-consuming equipment.

[0130] According to the power type, the vehicle can be a pure fuel-powered vehicle, a hybrid vehicle or a pure electric vehicle.

[0131] If the vehicle is a hybrid vehicle or a pure electric vehicle, the electrical energy stored in the lithium-ion battery is used to drive the vehicle's electric motor (electric motor) to output mechanical energy, which can be used to drive the vehicle to move.

[0132] If the vehicle is a hybrid vehicle, the electric energy stored in the lithium-ion battery can come from the electric energy output by the vehicle's external power grid, or the electric energy stored in the lithium-ion battery can come from the electric energy generated by the vehicle's generator, and the vehicle's internal combustion engine can burn and do work to drive the generator to generate the electric energy required by the lithium-ion battery.

[0133] If the vehicle is a pure electric vehicle, the electric energy stored in the lithium-ion battery can come from the electric energy output by the power grid outside the vehicle.

[0134] According to the above content, it can be known that the lithium-ion battery provided in the embodiment of the present application has the advantages of high charging rate and high discharge rate. Correspondingly, the vehicle in the embodiment of the present application also includes the advantages of high charging rate and discharge rate of the lithium-ion battery. The high charging rate makes the charging time of the vehicle relatively short, and the usable rate of the vehicle is high. The high discharge rate enables the lithium-ion battery to better meet the demand for large current output, and the vehicle equipped with the lithium-ion battery can have the advantages of longer endurance, greater acceleration capability, and stronger climbing ability. Therefore, the vehicle in the embodiment of the present application can bring users a better car experience.

[0135] It should be noted that the vehicle may include a battery pack, which may include a plurality of lithium-ion batteries. The plurality of lithium-ion batteries may be connected in series, in parallel, or in a mixed connection (including both series and parallel connection).

[0136] Depending on the purpose of the vehicle, the vehicle can be a car, truck, all-terrain vehicle, motorcycle, tricycle, two-wheeler, tractor or engineering vehicle.

[0137] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A negative electrode of a lithium ion battery, characterized in that The negative electrode comprises a negative electrode current collector, a silicon-based negative electrode body and a carbon-based negative electrode body; The negative electrode current collector comprises a plurality of current collecting columns intersecting in a mesh shape, and the negative electrode current collector is provided with a plurality of grid holes; At least a portion of the surface of a portion of the current collecting posts is surrounded and covered by the silicon-based negative electrode body, and at least a portion of the structure of the carbon-based negative electrode body is filled in the grid holes; A portion of the outer surface of the silicon-based negative electrode body is not covered by the carbon-based negative electrode body, and the silicon-based negative electrode body is used to directly contact with the electrolyte of the lithium-ion battery.

2. The negative electrode of a lithium ion battery according to claim 1, characterized in that The negative electrode comprises at least two cylindrical current collecting posts and at least two annular silicon-based negative electrode bodies; At least a portion of the structure of at least two of the current collecting columns is circumferentially covered by the at least one silicon-based negative electrode body corresponding to each of the two current collecting columns.

3. The negative electrode of a lithium ion battery according to claim 2, characterized in that The ratio of the inner diameter of the silicon-based negative electrode body to the outer diameter of the silicon-based negative electrode body is in the range of 0.6 to 0.

7.

4. The negative electrode of the lithium ion battery according to claim 3, characterized in that The thickness of the silicon-based negative electrode body is in the range of 15 μm to 20 μm.

5. The negative electrode of the lithium ion battery according to claim 1, characterized in that The area of ​​the portion of the outer surface of the silicon-based negative electrode body that contacts the carbon-based negative electrode body is a first area, and the area of ​​the portion of the outer surface of the silicon-based negative electrode body that contacts the electrolyte is a second area; The ratio of the first area to the second area is in the range of 1.5 to 2.

5.

6. The negative electrode of a lithium ion battery according to any one of claims 1 to 5, characterized in that The negative electrode current collector comprises at least two first negative electrode current collecting columns and at least two second negative electrode current collecting columns; The at least two first negative electrode current collecting columns extend along a first direction, the at least two second negative electrode current collecting columns extend along a second direction, and the first direction intersects the second direction; At least a portion of the surface of at least one of the first negative electrode current collectors is circumferentially covered by the silicon-based negative electrode body.

7. A method for preparing a negative electrode of a lithium ion battery, characterized in that: The preparation method comprises: Prepare a negative electrode current collector including a plurality of mesh-shaped cross-current collecting columns and provided with a plurality of grid holes; Coating the entire surface of the negative electrode current collector with a silicon-based negative electrode slurry; Drying the silicon-based negative electrode slurry to form a prefabricated silicon-based negative electrode body; Removing a local structure of the prefabricated silicon-based negative electrode body to form a silicon-based negative electrode body and expose a local structure of the negative electrode current collector; Filling the grid holes with carbon-based negative electrode slurry, and partially exposing the outer surface of the silicon-based negative electrode body to the carbon-based negative electrode slurry; The carbon-based negative electrode slurry is dried to form a carbon-based negative electrode body.

8. A method for preparing a negative electrode of a lithium ion battery, characterized in that: The preparation method comprises: providing at least two first negative electrode current collecting posts; Coating the first negative electrode current collecting column with silicon-based negative electrode slurry; Drying the silicon-based negative electrode slurry to form a silicon-based negative electrode body; Providing at least two second negative electrode current collecting columns, and making the extension direction of the second negative electrode current collecting columns intersect with the extension direction of the first negative electrode current collecting columns; Pressing the first negative electrode current collecting column and the second negative electrode current collecting column to form a negative electrode current collector provided with a plurality of grid holes; Filling the grid holes with carbon-based negative electrode slurry, and partially exposing the outer surface of the silicon-based negative electrode body to the carbon-based negative electrode slurry; The carbon-based negative electrode slurry is dried to form a carbon-based negative electrode body.

9. A lithium ion battery, characterized in that: The lithium-ion battery comprises a negative electrode as claimed in any one of claims 1 to 6; Alternatively, the lithium ion battery comprises a negative electrode prepared by the method for preparing a negative electrode of a lithium ion battery according to claim 7 or 8.

10. A vehicle, characterized in that: The vehicle includes the lithium-ion battery of claim 9.

Images