Battery and method of manufacturing the same

Abstract

The application provides a battery preparation method, comprising the following steps: preparing a positive electrode current collector and a negative electrode current collector by a physical vapor deposition method, wherein the positive electrode current collector and the negative electrode current collector are both three-dimensional porous structures, and the porosities of the positive electrode current collector and the negative electrode current collector are both 85%-99%; coating a positive electrode slurry on the positive electrode current collector and embedding the positive electrode slurry into the pores of the positive electrode current collector to form a positive electrode sheet; coating a negative electrode slurry on the negative electrode current collector and embedding the negative electrode slurry into the pores of the negative electrode current collector to form a negative electrode sheet; laminating or winding the positive electrode sheet, a separator and the negative electrode sheet to obtain the battery. The method provided by the application can improve the loading capacity on the current collector and the energy density of the battery. The application also provides a battery.

Description

Technical Field

[0001] This application relates to the technical field of batteries, and more particularly to a battery and a method for preparing the same. Background Technology

[0002] With the development of hybrid electric vehicles, the market demand for batteries is increasing. Batteries are attracting attention due to their high energy density and power density. Existing batteries use foamed metal and perforated metal as current collectors to improve the energy density of lithium batteries. However, current methods for treating current collectors mainly include laser drilling, powder metallurgy diffusion, and etching, which cause significant damage to the current collector structure and result in low loading of active material on the current collector. Summary of the Invention

[0003] In view of this, this application provides a method for preparing a battery to solve the above problems.

[0004] In addition, it is necessary to provide a battery prepared by this method.

[0005] This application provides a method for preparing a battery, comprising the following steps:

[0006] Positive and negative current collectors were prepared by physical vapor deposition. Both the positive and negative current collectors have three-dimensional porous structures and a porosity of 85%-99%.

[0007] The positive electrode slurry is coated onto the positive electrode current collector and embedded in the pores of the positive electrode current collector to form a positive electrode sheet;

[0008] The negative electrode slurry is coated onto the negative electrode current collector and embedded in the pores of the negative electrode current collector to form a negative electrode sheet.

[0009] The positive electrode, separator, and negative electrode are stacked or wound together to obtain the battery.

[0010] In some embodiments, the positive current collector is a porous aluminum or porous aluminum alloy current collector.

[0011] In some embodiments, the aluminum alloy current collector is an aluminum-nickel alloy current collector, and the negative electrode current collector is a porous copper or copper alloy current collector.

[0012] In some embodiments, the positive electrode slurry includes a first slurry and a second slurry. Both the first slurry and the second slurry contain a positive electrode active material and a conductive agent. When the first slurry and the second slurry have the same mass, the positive electrode active material accounts for a mass percentage m1 of the first slurry and a mass percentage m2 of the second slurry, with 2% < m1 - m2 < 5%. The conductive agent accounts for a mass percentage n1 of the first slurry and a mass percentage n2 of the second slurry, with 2% < n1 - n2 < 5%. The first slurry is embedded in the pores of the positive electrode current collector, and the second slurry is attached to the surface of the positive electrode current collector.

[0013] In some embodiments, the viscosity of the first slurry is 3000-5000 cpc, and the viscosity of the second slurry is 6000-10000 cpc.

[0014] In some embodiments, after coating the positive electrode slurry, the preparation method further includes compressing the positive electrode current collector containing the positive electrode slurry, drying it to form the positive electrode sheet, the thickness of the positive electrode sheet being 25%-33% of the thickness of the positive electrode current collector containing the positive electrode slurry.

[0015] In some embodiments, at least one of the positive current collector and the negative current collector has a tensile strength of 0.4-2 MPa.

[0016] In some embodiments, the preparation method further includes, prior to coating the positive electrode slurry and the negative electrode slurry:

[0017] A layer of carbon powder is coated onto the positive electrode current collector and the negative electrode current collector respectively by physical vapor deposition, resulting in a positive electrode current collector and a negative electrode current collector with a carbon layer on the surface, wherein the thickness of the carbon layer is 1-10 μm.

[0018] A battery is prepared by the method described above. The battery includes a cell formed by stacking or winding a positive electrode, a separator, and a negative electrode. The positive electrode includes a positive current collector and a positive active material layer disposed on the positive current collector. The negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector. Both the positive and negative current collectors have a three-dimensional porous structure. The positive and negative active material layers are also embedded in the pores of the positive and negative current collectors, respectively. The porosity of both the positive and negative current collectors is 85%-99%.

[0019] In some embodiments, a housing for housing the battery cell is also included, the housing being made of aluminum-plastic film.

[0020] In the battery of this application, both the positive and negative current collectors are prepared by physical vapor deposition, forming a three-dimensional porous structure with high porosity. The positive or negative electrode slurry not only adheres to the surface of the current collector but is also embedded in the pores of the current collector, thereby increasing the loading capacity of the current collector, which in turn improves the conductivity of the electrode and increases the energy density and power density of the battery. Attached Figure Description

[0021] Figure 1 This is a cross-sectional schematic diagram of a battery provided in one embodiment of this application.

[0022] Figure 2 This is a scanning electron microscope image of the porous aluminum current collector in Example 1.

[0023] Figure 3 This is a schematic diagram of the charge-discharge curve of the battery at 0.1C in Example 1.

[0024] Explanation of main component symbols

[0025] Battery 100

[0026] Battery Cell 10

[0027] Positive electrode 11

[0028] Positive current collector 111

[0029] Positive electrode active material layer 112

[0030] Negative electrode 12

[0031] Diaphragm 13

[0032] Casing 20 Detailed Implementation

[0033] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0034] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] This application provides a method for preparing a battery, which includes the following steps:

[0036] Step S1: A three-dimensional porous positive and negative current collector is prepared by physical vapor deposition, with a porosity of 85%-99%.

[0037] The porosity of the current collector is calculated using a true density meter.

[0038] In some embodiments, physical vapor deposition in this application includes the following steps:

[0039] (1) A magnetron sputtering system, operating in an argon atmosphere at 25-50℃ and an absolute pressure of 0.5-5Pa, controls the surface power of the metal (aluminum, copper, or alloy) target to be 2-10 W / cm². 2 A metal (or aluminum, copper, or alloy) layer 1-500 nm thick is deposited on one side of a porous polymer film by sputtering.

[0040] (2) High-temperature steam system: In a molten pool of metal, metal particles are melted and transformed into metal vapor with a partial pressure of 0.1-10% in the presence of inert gas nitrogen or argon.

[0041] (3) Low-temperature metal deposition system: In step (2), the inert gas carries the metal vapor to the low-temperature metal deposition system, and the metal is directly deposited on the metal layer. After a certain deposition time, a metal film is obtained. Nitrogen gas containing 2% oxygen is introduced at the outlet of the low-temperature metal deposition system to burn off the porous polymer film.

[0042] (4) Wrap the metal film around another porous polymer film and flip it over, and repeat steps (1)-(3) again to make the film thickness deposited on the two surfaces of the metal layer the same, thus obtaining the current collector.

[0043] In some embodiments, the tensile strength of the positive current collector and the negative current collector is 0.4-2 MPa. The tensile strength of the current collector used in this application is within the above range to ensure the flexibility of the current collector itself; in some embodiments, the compressive strength of the positive current collector and the negative current collector is 1-3.5 MPa, and the compressive strength of the current collector is within the above range to ensure the supporting strength of the current collector.

[0044] In some embodiments, the positive electrode current collector may be a porous aluminum or a porous aluminum alloy current collector. In some embodiments, the aluminum alloy current collector is a porous aluminum-nickel alloy current collector. The negative electrode current collector may be a porous copper or a porous copper alloy current collector.

[0045] Step S2: A carbon film is coated onto the positive current collector and the negative current collector respectively using a magnetron sputtering instrument to obtain a positive current collector and a negative current collector with a carbon layer on the surface, wherein the thickness of the carbon layer is 1-10 μm.

[0046] By covering the current collector with a carbon layer, the contact resistance between the current collector and the subsequently formed active material can be reduced.

[0047] Step S3: The positive electrode slurry is coated onto the positive electrode current collector with a carbon layer by a coating method. The positive electrode slurry is not only coated on the surface of the positive electrode current collector, but also embedded in the pores of the positive electrode current collector.

[0048] In some embodiments, the positive electrode slurry includes a positive electrode active material, a conductive agent, a binder, and a solvent; the positive electrode active material includes one or more of lithium manganese oxide, lithium cobalt oxide, nickel-cobalt-manganese ternary materials, or lithium iron phosphate. The conductive agent, binder, and solvent used are commonly used reagents and will not be described in detail here.

[0049] In some embodiments, the positive electrode slurry includes a first slurry and a second slurry. Both the first and second slurries contain a positive electrode active material and a conductive agent. The positive electrode active material accounts for a mass percentage m1 in the first slurry and m2 in the second slurry, where 2% < m1 - m2 < 5%, for example, the difference between m1 and m2 can be 2%, 3%, or 5%. The conductive agent accounts for a mass percentage n1 in the first slurry and n2 in the second slurry, where 2% < n1 - n2 < 5%, for example, the difference between n1 and n2 can be 2%, 3%, or 5%. The first slurry is embedded within the pores of the positive electrode current collector, and the second slurry is attached to both surfaces of the positive electrode current collector.

[0050] Compared to the second slurry, the percentage of positive electrode active material in the first slurry is larger, which can further increase the loading of positive electrode active material on the positive electrode current collector, thereby improving the energy density and power density of the battery. The percentage of conductive agent in the first slurry is smaller, but since the positive electrode current collector has a three-dimensional porous structure, it can still improve the conductivity of the positive electrode active material.

[0051] In some embodiments, the first slurry and the second slurry have the same composition, including the same positive electrode active material and conductive agent. In some embodiments, the first slurry and the second slurry differ in that the contents of the positive electrode active material and the conductive agent are different, and m1-m2=n1-n2.

[0052] In some embodiments, the viscosity of the first slurry is 3000-5000 cpc, and the viscosity of the second slurry is 6000-10000 cpc. The first and second slurries are within these ranges, ensuring adhesion of both slurries to the positive electrode current collector. The viscosity of the first slurry is lower than that of the second slurry, allowing the first slurry to flow more fully and uniformly into and embed into the pores of the positive electrode current collector.

[0053] In some embodiments, a first slurry is embedded into the pores of the positive electrode current collector by a slurry coating method, and a second slurry is attached to the two surfaces of the positive electrode current collector by an extrusion coating method.

[0054] Step S4: The negative electrode slurry is coated onto the negative electrode current collector with a carbon layer by a coating method. The negative electrode slurry is not only coated on the surface of the negative electrode current collector, but also embedded in the pores of the negative electrode current collector.

[0055] In some embodiments, the negative electrode slurry includes a negative electrode active material, a conductive agent, a binder, and a solvent, wherein the negative electrode active material includes one or more of graphite, carbon nanotubes, or carbon black.

[0056] In some embodiments, the negative electrode slurry includes a third slurry and a fourth slurry, both of which contain a negative electrode active material and a conductive agent. The negative electrode active material in the third slurry accounts for m3 by mass, and the negative electrode active material in the fourth slurry accounts for m4 by mass, where 2% < m3 - m4 < 5%. For example, the difference between m3 and m4 can be 2%, 3%, or 5%. The conductive agent in the third slurry accounts for n3 by mass, and the conductive agent in the fourth slurry accounts for n4 by mass, where 2% < n3 - n4 < 5%. For example, the difference between n3 and n4 can be 2%, 3%, or 5%. The third slurry is used to embed within the pores of the negative electrode current collector, and the fourth slurry is attached to both surfaces of the negative electrode current collector.

[0057] In some embodiments, the method and process of coating the negative electrode slurry onto the negative electrode current collector are the same as the method and process of coating the positive electrode slurry onto the negative electrode current collector.

[0058] Step 5: Compress and dry the positive current collector containing the positive electrode slurry to form a positive electrode sheet. The thickness of the positive electrode sheet is 25%-33% of the thickness of the positive current collector containing the positive electrode slurry.

[0059] Furthermore, the negative electrode current collector containing the negative electrode slurry can be compressed and dried to form the negative electrode sheet. The thickness of the negative electrode sheet is 25%-33% of the thickness of the negative electrode current collector containing the negative electrode slurry.

[0060] Compared to current collectors of the same size and under the same loading conditions, the thickness of the positive electrode sheet of this application is 25%-33% of the thickness of the positive current collector containing the positive electrode slurry, and the thickness of the negative electrode sheet is 25%-33% of the thickness of the negative current collector containing the negative electrode slurry. This is beneficial to improving the energy density and power density of the battery, and also meets the production requirements for the volume of the electrode sheet.

[0061] Step 6: Stack or wind the positive electrode, separator, and negative electrode to obtain the battery.

[0062] In the battery assembled in this application, both the positive and negative current collectors are prepared using physical vapor deposition (PVD), resulting in current collectors with high porosity and avoiding the structural damage caused by existing drilling techniques. Furthermore, due to the higher porosity of the current collector, the current collector used in this application can load more slurry onto the same size current collector, increasing the electrode loading, improving electrode conductivity, and further enhancing the battery's energy density and power density. On the other hand, compared to current collectors prepared using existing powder metallurgy, the current collector prepared using this application contains fewer impurities, the metal current collector is less prone to oxidation, and alloys with different mixing ratios can be prepared according to application requirements, resulting in a wider range of applications. The metal material of the current collector prepared in this application has good flexibility and low resistance. Simultaneously, the use of PVD allows for control over the thickness of the current collector.

[0063] See Figure 1 This application also provides a battery 100, manufactured by the above-described method. The battery 100 includes a cell 10, which is formed by stacking or winding a positive electrode 11, a separator 13, and a negative electrode 12. The separator 13 is disposed between the positive electrode 11 and the negative electrode 12. The positive electrode 11 includes a positive current collector 111 and a positive active material layer 112 disposed on the positive current collector 111. The negative electrode 12 includes a negative current collector 121 and a negative active material layer 122 disposed on the negative current collector 121. Both the positive current collector 111 and the negative current collector 121 have a three-dimensional porous structure. The positive active material layer 112 and the negative active material layer 122 are also embedded in the pores of the positive current collector 111 and the negative current collector 121, respectively. The porosity of both the positive current collector 111 and the negative current collector 121 is 85%-99%. In some embodiments, the positive electrode active material layer 112 is formed from a positive electrode slurry, and the negative electrode active material layer 122 is formed from a negative electrode slurry.

[0064] In some embodiments, the battery 100 further includes a housing 20, within which the battery cell 10 is housed. An electrolyte is also disposed within the housing 20.

[0065] In some embodiments, the outer casing 20 is made of aluminum-plastic film material, meaning the battery 100 can specifically be a pouch battery. In other embodiments, the outer casing 20 can also be a steel casing or an aluminum casing.

[0066] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following examples are for illustrative purposes only and should not be construed as limiting the invention. Unless otherwise stated, reagents, software, and instruments involved in the following embodiments that are not specifically described are all conventional commercially available products or open-source materials.

[0067] Example 1

[0068] Preparation of positive electrode:

[0069] Add 4% by weight of polyvinylidene fluoride [product model: PVDF5130] to N-methylpyrrolidone [NMP] and stir until completely dissolved to obtain a colloid.

[0070] 91% by weight of lithium iron phosphate, 2% conductive carbon black (SP-Li), 1% carbon nanotubes (CNTs), and 2% PVDF powder were added to the colloid, mixed thoroughly, and stirred until homogeneous to obtain the first slurry with a viscosity of 3500 cpc. 89% by weight of lithium iron phosphate, 4% conductive carbon black (SP-Li), 1% carbon nanotubes (CNTs), and 2% PVDF powder were added to the colloid, mixed thoroughly, and stirred until homogeneous to obtain the second slurry with a viscosity of 6500 cpc.

[0071] A 6 μm thick carbon layer is deposited on the porous aluminum current collector using a magnetron sputtering apparatus. The porous aluminum current collector has a porosity of 90% and a tensile strength of 0.6 MPa. A first slurry is then applied to fill the pores of the porous aluminum current collector using a slurry-drawing method and dried. The first slurry is then coated onto the dried porous aluminum current collector using an extrusion coating method to a thickness of 600–1000 μm. After drying, the coating is rolled, slit, tabs are welded, adhesive is applied, and the surface is baked to obtain a positive electrode sheet. At this point, the thickness of the positive electrode sheet is approximately one-third of the thickness of the porous aluminum current collector containing the positive electrode slurry.

[0072] Preparation of negative electrode:

[0073] An active material with a solid content of 45% is mixed with a solvent. The active material comprises 91.5% active material graphite, 1% conductive agent carbon nanotubes, 3% conductive carbon black, and 4.5% polyvinylidene fluoride binder. The solvent is N-methylpyrrolidone. The active material and the solvent are mixed and stirred to obtain a third slurry with a viscosity of 4000 cpc. The active material comprises 93.5% active material graphite, 1% conductive agent carbon nanotubes, 1% conductive carbon black, and 4.5% polyvinylidene fluoride binder. The active material and the solvent are mixed and stirred to obtain a fourth slurry with a viscosity of 7000 cpc.

[0074] A 6 μm thick carbon layer is deposited on the porous copper current collector using a magnetron sputtering apparatus. The porous copper current collector has a porosity of 90% and a tensile strength of 1.6 MPa. A third slurry is then applied to fill the pores of the porous copper current collector using a slurry-drawing method and dried. A fourth slurry is then applied to the dried porous copper current collector using an extrusion coating method, with a coating thickness of 600–1000 μm. After drying, the coating is rolled, slit, tabs are welded, adhesive is applied, and it is baked to obtain the negative electrode sheet. At this point, the thickness of the negative electrode sheet is one-third of the thickness of the porous copper current collector containing the negative electrode slurry.

[0075] The battery uses a wet-process separator commonly used in lithium batteries, and the electrolyte is lithium hexafluorophosphate and fluoroethylene carbonate [FEC]. The positive electrode, negative electrode, and separator are wound to form a core, then short-circuited, loaded with aluminum-plastic film, packaged, short-circuited again, corner pressed, baked, and then injected with electrolyte, pre-sealed, activated, formed, repackaged, and capacity tested to produce the pouch battery.

[0076] In this embodiment, a sample measuring 1.17mm*13800mm was prepared. 2 The prepared pouch cell was tested for volumetric power density and volumetric energy density.

[0077] The porous aluminum current collector obtained in Example 1 was subjected to scanning electron microscopy (SEM) testing, and the results are as follows: Figure 2 As shown. From Figure 2 As can be seen, the porous aluminum current collector has a three-dimensional porous structure.

[0078] The electrochemical performance of the pouch cell obtained in Example 1 was tested. (See attached document.) Figure 3 The specific test steps are as follows: the soft pack battery is charged to 4.35V at a current of 0.95A, kept under constant voltage for 30 minutes or cut off at a current of 3.8mA, and then discharged to a termination voltage of 3V under a constant current of 0.95A. The discharge energy at this time is 6.56Wh, and the discharge capacity obtained at this time is calculated to be 1.74Ah, and the discharge volumetric energy density is 406.12Wh / L.

[0079] The formula for calculating energy density is: Energy density (Wh / L) = Discharge energy (Wh) / [Cell area (dm²)] 2 () × cell thickness (dm)

[0080] Constant power discharge time, volumetric power, and volumetric energy density: The pouch cell was charged to 4.35V at 0.5C, maintained at constant voltage for 30 minutes or cutoff current of 0.02C, and allowed to rest for 10 minutes. Then, it was discharged at different powers to a 2V termination voltage, and allowed to rest for 10 minutes after discharge. The discharge time of the pouch cell was recorded for each power, and the average discharge volumetric power density and volumetric energy density of the three discharges were calculated, as shown in Table 1. The formula for calculating power density is: Power density (kW / L) = Discharge power (W) / [Cell area (cm²)] 2 () × cell thickness (cm)

[0081] Table 1. Constant power discharge performance of the pouch cells prepared in Example 1

[0082]

[0083] As shown in Table 1, the discharge volume power density gradually increases with the increase of discharge power, reaching 15.42 kW / L at 250 W.

[0084] Example 2

[0085] Preparation of positive electrode:

[0086] The difference from Example 1 is that "lithium iron phosphate" is replaced with "lithium cobalt oxide", the porosity of the porous aluminum current collector is 95%, and the tensile strength of the porous aluminum current collector is 0.5 MPa. The remaining steps are the same as the preparation steps of the positive electrode in Example 1.

[0087] Negative electrode preparation:

[0088] The difference from Example 1 is that the porosity of the porous copper current collector is 95%, and the tensile strength of the porous copper current collector is 1.2 MPa. The remaining steps are the same as the preparation steps of the negative electrode in Example 1.

[0089] In this embodiment, a sample measuring 1.17mm*13800mm was prepared. 2 The prepared pouch cell was tested for volumetric power density and volumetric energy density.

[0090] The electrochemical performance of the pouch cell obtained in Example 2 was tested. The specific test steps were as follows: the pouch cell was charged to 4.25V at a current of 0.19A, kept under constant voltage for 30 minutes or cut off at a current of 3.8mA, and then discharged to a termination voltage of 3V at a constant current of 0.19A. At this point, the discharge capacity was 1.95Ah and the discharge volumetric energy density was 375.47Wh / L.

[0091] Constant power discharge time, volumetric power and volumetric energy density: The pouch battery was charged to 4.25V at 0.5C, with a cutoff current of 0.02C, and left to stand for 30 minutes. Then it was discharged to a 2.5V termination voltage at different powers. After the discharge was completed, it was left to stand for 30 minutes. The discharge time of the pouch battery was recorded for each power. The average discharge volumetric power density and volumetric energy density of the three discharges were calculated, as shown in Table 2.

[0092] Table 2. Constant power discharge performance of the pouch cells prepared in Example 2

[0093]

[0094]

[0095] As shown in Table 2, the discharge volume power density gradually increases with the increase of discharge power, reaching 14.99 kW / L at 300 W.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention should not depart from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a battery, characterized in that, Includes the following steps: Positive and negative current collectors were prepared by physical vapor deposition. Both the positive and negative current collectors have three-dimensional porous structures with a porosity of 85%-99%. A positive electrode slurry is coated onto the positive electrode current collector and embedded within the pores of the current collector to form a positive electrode sheet. The positive electrode slurry includes a first slurry and a second slurry. Both the first slurry and the second slurry contain a positive electrode active material and a conductive agent. In the first slurry, the positive electrode active material accounts for a mass percentage m1, and in the second slurry, the positive electrode active material accounts for a mass percentage m2, where 2% < m1 - m2 < 5%. In the first slurry, the conductive agent accounts for a mass percentage n1, and in the second slurry, the conductive agent accounts for a mass percentage n2, where 2% < n2 - n1 < 5%. The viscosity of the first slurry is lower than that of the second slurry. The first slurry is embedded within the pores of the positive electrode current collector by a slurry-coating method, and the second slurry is attached to the surface of the positive electrode current collector by an extrusion coating method. The negative electrode slurry is coated onto the negative electrode current collector and embedded in the pores of the negative electrode current collector to form a negative electrode sheet. The positive electrode, separator, and negative electrode are stacked or wound together to obtain the battery.

2. The method for preparing the battery as described in claim 1, characterized in that, The positive electrode current collector is a porous aluminum or porous aluminum alloy current collector.

3. The method for preparing the battery as described in claim 2, characterized in that, The aluminum alloy current collector is an aluminum-nickel alloy current collector, and the negative electrode current collector is a porous copper or copper alloy current collector.

4. The method for preparing the battery as described in claim 1, characterized in that, The viscosity of the first slurry is 3000-5000 cpc, and the viscosity of the second slurry is 6000-10000 cpc.

5. The method for preparing the battery as described in claim 1, characterized in that, After coating the positive electrode slurry, the preparation method further includes compressing the positive electrode current collector containing the positive electrode slurry, drying it to form the positive electrode sheet, the thickness of the positive electrode sheet being 25%-33% of the thickness of the positive electrode current collector containing the positive electrode slurry.

6. The method for preparing the battery according to claim 1, characterized in that, The tensile strength of at least one of the positive current collector and the negative current collector is 0.4-2 MPa.

7. The method for preparing the battery as described in claim 1, characterized in that, Before coating the positive electrode slurry and the negative electrode slurry, the preparation method further includes: A layer of carbon powder is coated onto the positive electrode current collector and the negative electrode current collector respectively by physical vapor deposition, resulting in a positive electrode current collector and a negative electrode current collector with a carbon layer on the surface, wherein the thickness of the carbon layer is 1-10 μm.

8. A battery, prepared by the method of any one of claims 1 to 7, characterized in that, The battery includes a cell, which is formed by stacking or winding the positive electrode, the separator, and the negative electrode. The positive electrode includes a positive current collector and a positive active material layer disposed on the positive current collector. The negative electrode includes a negative current collector and a negative active material layer disposed on the negative current collector. Both the positive and negative current collectors have a three-dimensional porous structure. The positive and negative active material layers are also embedded in the pores of the positive and negative current collectors, respectively. The porosity of both the positive and negative current collectors is 85%-99%.

9. The battery as claimed in claim 8, characterized in that, The battery also includes a housing for containing the battery cells, the housing being made of aluminum-plastic film.

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