A battery, a preparation method thereof, a battery pack, an electric device, and a quality control method of the battery

Abstract

This invention provides a battery and its preparation method, a battery pack, an electrical device, and a quality control method for the battery. The battery includes a positive electrode and a negative electrode. The positive electrode includes a positive current collector and a positive active material layer present on at least one side of the positive current collector. The negative electrode includes a negative current collector and a negative active material layer present on at least one side of the negative current collector. The battery satisfies: 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c )≤0.100; where, CD c The compaction density of the positive electrode active material layer, expressed in g / cm³. 3 Calculation; CD a The compaction density of the negative electrode active material layer, expressed in g / cm³. 3 Calculation; T c T represents the thickness of the positive electrode active material layer, expressed in μm. a The thickness of the negative electrode active material layer is expressed in μm. The battery exhibits high ion transport and electronic conductivity, resulting in both high cycle performance and rate capability.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery and its preparation method, a battery pack, an electrical device, and a battery quality control method. Background Technology

[0002] Solid-state batteries use solid electrolyte materials (such as oxides, sulfides, polymers, or composite electrolytes) to replace flammable and volatile organic liquid electrolytes. These solid electrolyte materials have extremely low volatility and excellent thermal stability, and will not leak, burn, or explode even in high-temperature environments, eliminating the risks of electrolyte leakage, combustion, and explosion. At the same time, their high mechanical strength can effectively suppress lithium dendrite penetration generated by the negative electrode during cycling, prevent internal short circuits, and greatly improve battery safety.

[0003] However, in solid-state batteries, active metal ions rely entirely on solid-phase transport, resulting in poor ion transport rate and electronic conductivity, which leads to a decrease in the cycle performance and rate performance of solid-state batteries.

[0004] Therefore, it is urgent to improve the ion transport rate and electronic conductivity of solid-state batteries in order to improve both the cycle performance and rate performance of solid-state batteries. Summary of the Invention

[0005] This invention provides a battery and its preparation method, a battery pack, an electrical device, and a battery quality control method. The battery has high internal ion transport rate and electronic conductivity, and the battery has high cycle performance and rate performance.

[0006] This invention provides a battery, including a positive electrode and a negative electrode, wherein the positive electrode includes a positive current collector and a positive active material layer present on at least one side of the positive current collector;

[0007] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer present on at least one side of the negative electrode current collector;

[0008] The battery satisfies: 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c ≤0.100;

[0009] Among them, CD c The compaction density of the positive electrode active material layer is expressed in g / cm³. 3 count;

[0010] CD a The compaction density of the negative electrode active material layer is expressed in g / cm³. 3 count;

[0011] Tc The thickness of the positive electrode active material layer is expressed in μm.

[0012] T a The thickness of the negative electrode active material layer is expressed in μm.

[0013] In some embodiments of the present invention, the battery satisfies: 0.064 ≤ (CD) a ×T a ) / (CD) c ×T c ≤0.075.

[0014] In some embodiments of the present invention, 0.9 ≤ CD a ≤1.2, preferably, 0.95≤CD a ≤1.15;

[0015] And / or, 3.0≤CD c ≤3.4, preferably, 3.1≤CD c ≤3.3;

[0016] And / or, 10≤T a ≤30, preferably, 15≤T a ≤27;

[0017] And / or, 90≤T c ≤113, preferably, 95≤T c ≤110.

[0018] In some embodiments of the present invention, the areal density of the positive electrode active material layer is 270 g / m². 2 ~385 g / m 2 ;

[0019] And / or, the areal density of the negative electrode active material layer is 20 g / m³. 2 ~36 g / m 2 .

[0020] In some embodiments of the present invention, the positive electrode active layer material layer includes a positive electrode active material and a solid electrolyte material;

[0021] The positive electrode active material is preferably a layered positive electrode active material;

[0022] The solid electrolyte material is preferably a sulfide solid electrolyte.

[0023] In some embodiments of the present invention, the layered positive electrode active material includes Li a Ni x Co y Mn z M b O 2-cX c One or more of LiCoO2 and LiNiO2;

[0024] Wherein, M is selected from one or more of Zr, Ti, Sb, Ta, Nb, Y, W, B, Al, Sr, Mo, Mg, and Nd, and X is selected from one or more of F, Cl, and Br, 0.9≤a≤1.1, x+y+z+b+c=1, 0<x<1, 0<y<1, 0<z<1, 0≤b≤0.1, and 0≤c≤0.1;

[0025] And / or, the sulfide solid electrolyte includes Li3PS4, Li7P3S 11 Li 11 GeP2S 12 Li6PS5Cl, Li7P2S8I, Li 10 SnP2S 12 Li 3 .25 Ge 0 .25 P 0 .75 One or more of S4.

[0026] In some embodiments of the present invention, the average particle size of the positive electrode active material is 4 μm to 7 μm;

[0027] And / or, the average particle size of the solid electrolyte material is 1 μm to 4 μm.

[0028] In some embodiments of the present invention, the battery is a solid-state battery, and the solid-state battery further includes a solid electrolyte membrane disposed between the positive electrode and the negative electrode.

[0029] This invention also provides a method for preparing the battery as described above, comprising the following steps: coating a positive electrode slurry onto at least one side surface of a positive electrode current collector, and sequentially performing a first drying treatment and a first rolling treatment to obtain a positive electrode sheet;

[0030] The negative electrode slurry is coated onto at least one side of the negative electrode current collector, and then the negative electrode sheet is obtained after passing through a second drying process and a second rolling process.

[0031] The battery is obtained by assembling the positive electrode and the negative electrode.

[0032] By adjusting the pressure of the first and second rolling processes, the battery is made to satisfy: 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c ≤0.100.

[0033] In some embodiments of the present invention, the pressure of the first rolling process is 350 MPa to 600 MPa;

[0034] And / or, the pressure of the second rolling process is 300 MPa to 600 MPa.

[0035] This invention also provides a battery pack comprising at least two batteries as described above, or a battery prepared by a method comprising at least two batteries as described above.

[0036] The present invention also provides an electrical device, including the battery as described above, or the battery prepared by the method described above, or the battery pack as described above.

[0037] This invention also provides a battery quality control method, comprising the following steps:

[0038] The current structural parameters of the positive electrode active material layer and the negative electrode active material layer of the battery are detected;

[0039] Determine whether the current structural parameters meet the preset threshold;

[0040] Wherein, the preset threshold is 0.061≤ ≤0.100, the current structural parameter is calculated according to the following formula:

[0041] =CD a ×T a ) / (CD) c ×T c ), 0.061≤ ≤0.100;

[0042] in, ;

[0043] CD c The compaction density of the positive electrode active material layer is expressed in g / cm³. 3 count;

[0044] CD a The compaction density of the negative electrode active material layer is expressed in g / cm³. 3 count;

[0045] T c The thickness of the positive electrode active material layer is expressed in μm.

[0046] T a The thickness of the negative electrode active material layer is expressed in μm.

[0047] In some embodiments of the present invention, the battery quality control method further includes: if the current structural parameters of the battery do not meet the preset threshold, performing a first rolling process on the positive electrode and a second rolling process on the negative electrode until the current structural parameters of the battery meet the preset threshold.

[0048] This invention provides a battery and its manufacturing method, a battery pack, an electrical device, and a battery quality control method, which ensure that the battery satisfies 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c A value ≤0.100 can result in higher ion transport rate and electronic conductivity inside the battery, giving the battery both high cycle performance and rate performance. Attached Figure Description

[0049] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0050] Figure 1 This is a schematic diagram of the battery structure according to an embodiment of the present invention.

[0051] Explanation of reference numerals in the attached figures

[0052] 1: Negative electrode active material layer; 2: Solid electrolyte layer; 3: Positive electrode active material layer.

[0053] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0055] Currently, solid-state batteries suffer from poor ion transport rate and electronic conductivity, which limits their application.

[0056] The inventors attempted to optimize the areal capacity or specific capacity of the positive and negative electrodes in solid-state batteries, but failed to effectively improve the problem of poor ion transport rate and electronic conductivity in solid-state batteries.

[0057] Through research, the inventors found that the compaction density and thickness of the positive and negative electrode sheets have a significant impact on the ion transport rate and electronic conductivity inside the solid-state battery. Therefore, simply optimizing the areal capacity or specific capacity of the positive and negative electrode sheets in the solid-state battery cannot effectively improve the cycle performance and rate performance of the battery.

[0058] Therefore, the inventors started by improving the ion transport rate and electronic conductivity inside the solid-state battery in order to improve the battery's cycle performance and rate performance.

[0059] Based on this, embodiments of the present invention provide a battery, including a positive electrode and a negative electrode. The positive electrode includes a positive current collector and a positive active material layer present on at least one side of the positive current collector; the negative electrode includes a negative current collector and a negative active material layer present on at least one side of the negative current collector; the battery satisfies: 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c )≤0.100; where, CD c The compaction density of the positive electrode active material layer, expressed in g / cm³. 3 Calculation; CD a The compaction density of the negative electrode active material layer, expressed in g / cm³. 3 Calculation; T c T represents the thickness of the positive electrode active material layer, expressed in μm. a The thickness of the negative electrode active material layer is expressed in μm.

[0060] The battery provided in this embodiment of the invention has high internal ion transport rate and electronic conductivity, and the battery has high cycle performance and rate performance.

[0061] The inventors analyzed that the reason why the battery of the present invention has high cycle performance and rate performance is that the battery satisfies 0.061 ≤ (CD) a ×T a ) / (CD) c ×T cWhen the concentration of active metal ions is ≤0.100, it ensures that active metal ions migrate rapidly from the positive electrode to the negative electrode surface and embed themselves quickly. It also improves the uniformity of active metal ion embedding in the negative electrode active material layer, reduces the diffusion distance of active metal ions in the positive and negative electrode sheets, and increases the ion transport rate inside the battery, resulting in better rate performance. When the battery meets the above conditions, it also ensures the continuity of the electronic conductivity network in the positive and negative electrode active material layers, resulting in high electronic conductivity, which is beneficial for uniform current distribution, promotes uniform lithium deposition, and inhibits dendrite growth, thus improving the battery's cycle performance. Therefore, the battery of this invention possesses both good cycle performance and rate performance.

[0062] For example, (CD) a ×T a ) / (CD) c ×T c The value of ) is, for example, 0.061, 0.065, 0.070, 0.080, 0.090, 0.100, or a range of any two of them.

[0063] The embodiments of the present invention can use conventional testing methods and instruments in the art to test the compaction density of the positive electrode active material layer, the thickness of the positive electrode active material layer, the compaction density of the negative electrode active material layer, and the thickness of the negative electrode active material layer.

[0064] In this embodiment of the invention, the method for measuring the thickness of the positive and negative active material layers specifically includes the following steps: After the battery is fully discharged, it is disassembled to separate the positive and negative electrode sheets. Taking the positive electrode sheet as an example, a sample of the positive electrode sheet is cut, and then the cross-section of the positive electrode sheet is obtained by cutting the positive electrode sheet with an argon ion beam. The cross-section of the positive electrode sheet is observed in an SEM. The SEM voltage and magnification are adjusted according to actual needs. The thickness of the positive active material layer is measured using the measurement tools provided with the SEM. A total of 20-30 experiments are conducted, and the thickness value of the positive active material layer is statistically obtained. The thickness test of the negative active material layer is similar and will not be described in detail. In addition, this embodiment can also test the positive and negative electrode sheets that are not assembled into the battery to evaluate their impact on the cycle performance and rate performance when assembled into the battery. This is beneficial for screening positive and negative electrode sheets that can improve the cycle performance and rate performance of the battery before assembly.

[0065] In this embodiment of the invention, the compaction density of the positive electrode active material layer is equal to the mass of the positive electrode active material layer divided by its volume. The mass of the positive electrode active material layer can be obtained using an electronic balance with an accuracy of 0.01g or higher. The volume of the positive electrode active material layer is the product of the area of ​​the plane perpendicular to the thickness direction and the thickness of the positive electrode active material layer. The testing process for the thickness of the positive electrode active material layer is as described above, and the area of ​​the plane perpendicular to the thickness direction can be obtained using a laser rangefinder. The compaction density of the negative electrode active material layer is similar and will not be repeated here.

[0066] In some embodiments of the present invention, the battery satisfies: 0.064 ≤ (CD) a ×T a ) / (CD) c ×T c When (CD) ≤ 0.075, the ion transport rate and electronic conductivity inside the battery are further improved, and the cycle performance and rate performance of the battery are further improved. For example, (CD) a ×T a ) / (CD) c ×T c The value of ) is, for example, a range of 0.064, 0.068, 0.07, 0.075, or any two of them.

[0067] In some embodiments, 0.9 ≤ CD a When the concentration is ≤1.2, it is beneficial to further enrich the diffusion paths of ions and electrons in the positive electrode active material layer. For example, CD a The value is, for example, a range of 0.9, 1, 1.1, 1.2, or any two of these. Preferably, 0.95 ≤ CD a ≤1.15.

[0068] In some embodiments, 3.0 ≤ CD c At a concentration ≤3.4, it is beneficial to further enrich the diffusion paths of ions and electrons in the positive electrode active material layer. For example, CD c The value is, for example, a range of 3.0, 3.1, 3.2, 3.3, 3.4, or any combination thereof. Preferably, 3.1 ≤ CD. c ≤3.3.

[0069] In some embodiments, 10≤T a When the temperature is ≤30, the ion transport rate and electronic conductivity in the positive electrode active material layer are further improved. For example, T a The value is, for example, a range of 10, 15, 20, 25, 30, or any combination thereof. Preferably, 15 ≤ T. a ≤27.

[0070] In some embodiments, 90≤T c When the value is ≤113, the ion transport rate and electronic conductivity in the negative electrode active material layer are further improved. For example, T c The value is, for example, a range of 90, 95, 100, 105, 110, 113, or any combination thereof. Preferably, 95 ≤ T c ≤110.

[0071] In some embodiments of the present invention, the inventors further improve the ion transport rate and electronic conductivity of the electrode by controlling the areal density of the electrode (at least one of the positive electrode and the negative electrode).

[0072] In some embodiments, the areal density of the positive electrode active material layer is 270 g / m². 2 ~385 g / m 2 For example, the areal density of the positive electrode active material layer is, for instance, 270 g / m². 2 300 g / m 2 350 g / m 2 385 g / m 2 Or a range consisting of any two of them.

[0073] In some embodiments, the areal density of the negative electrode active material layer is 20 g / m². 2 ~36 g / m 2 For example, the areal density of the negative electrode active material layer is, for instance, 20 g / m². 2 25 g / m 2 30 g / m 2 35 g / m 2 36 g / m 2 Or a range consisting of any two of them.

[0074] In this embodiment of the invention, the testing process for the areal density of the positive electrode active material layer may include: taking a sample of the positive electrode active material layer, testing the total mass m1 of the sample, and the surface area S of one side of the positive electrode active material layer in the thickness direction; then scraping off the positive electrode active material layer from the positive electrode sample, and testing the mass m2 of the obtained positive electrode current collector. The areal density of the positive electrode active material layer is then calculated as (m1 - m2) / S. The testing method for the areal density of the negative electrode active material layer is similar and will not be described in detail here. Specifically, the above areal density refers to the areal density of one side.

[0075] In some embodiments of the present invention, the positive electrode active layer material includes a positive electrode active material and a solid electrolyte material; the positive electrode active material is preferably a layered positive electrode active material; the solid electrolyte material is preferably a sulfide solid electrolyte, which can further improve the ion transport rate and electronic conductivity of the electrode, thereby further improving the cycle performance and rate performance of the battery.

[0076] The battery in this embodiment of the invention can be a lithium-ion battery (such as a lithium-ion power battery).

[0077] In detail, in the embodiments of the present invention, the solid electrolyte material in the positive electrode active material layer can be a conventional solid electrolyte material in the art. For example, the solid electrolyte in the positive electrode active material layer may include at least one of sulfide solid electrolyte and halide solid electrolyte, and the solid electrolyte material is preferably a sulfide solid electrolyte.

[0078] In some embodiments, the battery is an all-solid-state lithium-ion battery, and the positive electrode active material may include LiCoO2, LiNiO2, or LiCo. x Ni 1-x O2 (0≤x≤1), LiCo x Ni 1-x-y Al y O2 (0≤x≤1, 0≤y≤1), LiMn2O4, LiFe x Mn y M z O4 (M is one or more of Al, Mg, Ga, Cr, Co, Ni, Cu, Zn or Mo, 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1), Li 1＋x L 1－y－z M y N z O2 (L, M, N are one or more of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1), LiFePO4, Li3V2(PO4)3, Li3V3(PO4)3, LiVPO4F, Li2CuO2, Li5FeO4, and metal sulfides and oxides (such as TiS2, V2S3, FeS, FeS2, LiMS) x (M is at least one of the transition metal elements such as Ti, Fe, Ni, Cu, Mo, etc., 1≤x≤2.5), TiO2, Cr3O8, V2O5, MnO2, etc.

[0079] In some embodiments, the layered positive electrode active material includes Li a Ni x Co y Mn z M b O 2-c X cOne or more of LiCoO2 and LiNiO2; wherein M is selected from one or more of Zr, Ti, Sb, Ta, Nb, Y, W, B, Al, Sr, Mo, Mg, and Nd, and X is selected from one or more of F, Cl, and Br. When 0.9≤a≤1.1, x+y+z+b+c=1, 0<x<1, 0<y<1, 0<z<1, 0≤b≤0.1, and 0≤c≤0.1, the ion transport rate and electronic conductivity of the electrode can be further improved, thereby further improving the cycle performance and rate performance of the battery.

[0080] In some embodiments, the sulfide solid electrolyte includes Li3PS4 and Li7P3S. 11 Li 11 GeP2S 12 Li6PS5Cl, Li7P2S8I, Li 10 SnP2S 12 Li 3 .25 Ge 0 .25 P 0 .75 One or more of S4 can further improve the ion transport rate and electronic conductivity of the battery electrodes, thereby further improving the cycle performance and rate performance of the battery.

[0081] To further improve the ion transport rate and electronic conductivity inside the battery, the embodiments of the present invention control the average particle size of the positive electrode active material and the average particle size of the solid electrolyte material.

[0082] In some embodiments, when the average particle size of the positive electrode active material is 4 μm to 7 μm, the cycle performance and rate performance of the battery are further improved. For example, the average particle size of the positive electrode active material is, for example, a range of 4 μm, 5 μm, 6 μm, 7 μm, or any combination thereof.

[0083] In some embodiments, when the average particle size of the solid electrolyte material is 1 μm to 4 μm, the cycle performance and rate performance of the battery are further improved. For example, the average particle size of the solid electrolyte material is, for example, a range of 1 μm, 2 μm, 3 μm, 4 μm, or any combination thereof.

[0084] This invention allows for the testing of the average particle size of the positive electrode active material and the average particle size of the solid electrolyte material using conventional testing methods and instruments in the art, such as SEM. Specifically, the average particle size of the positive electrode active material and the solid electrolyte material can be tested using the following process: First, a fully discharged battery is disassembled to obtain the positive electrode sheet. Then, an arbitrary location in the positive electrode active material layer region of the positive electrode sheet is cut using argon ions to obtain a cross-sectional sample of the positive electrode sheet. Next, the cross-sectional sample of the positive electrode sheet is placed in an SEM for observation. The SEM voltage and magnification are adjusted according to actual needs to ensure that a sufficient amount of positive electrode active material and solid electrolyte material in the sample can be clearly seen and photographed to obtain an SEM image. The maximum particle size of the positive electrode active material or solid electrolyte material can be directly observed through the SEM image. 10-30 experiments are conducted cumulatively, with different distribution locations on the positive electrode sheet being tested. After statistical analysis of the results, the sum of the maximum particle sizes of multiple positive electrode active materials or solid electrolyte materials is calculated and divided by the number of positive electrode active materials or solid electrolyte materials to obtain the average particle size of the positive electrode active material or solid electrolyte material.

[0085] In detail, the positive electrode active material in the embodiments of the present invention can be monocrystalline or polycrystalline. Monocrystalline particles appear as individual primary particles dispersed in the above SEM images, while polycrystalline particles are formed by the agglomeration of primary particles to form secondary particles.

[0086] The battery in this embodiment of the invention can be a solid-state battery, which further includes a solid electrolyte membrane disposed between the positive electrode and the negative electrode.

[0087] The present invention does not impose any special limitations on the preparation of solid electrolyte membranes, and the selection can be made according to the actual situation.

[0088] like Figure 1 As shown, the battery of this embodiment includes a negative electrode active material layer 1, a positive electrode active material layer 3, and a solid electrolyte layer 2 located between the negative electrode active material layer 1 and the positive electrode active material layer 3.

[0089] In one specific embodiment, the solid electrolyte membrane can be prepared by the following method: Preparation of the solid electrolyte membrane: Solid electrolyte material and binder are mixed at a mass ratio of 98:2, xylene solvent is added, and a uniform solid electrolyte slurry is formed under the action of a mechanical stirrer. Then, the solid electrolyte slurry is coated onto a substrate, and after drying, a solid electrolyte membrane is obtained. The solid electrolyte material in the solid electrolyte slurry can be Li3PS4 or Li7P3S. 11 Li 11 GeP2S 12 Li6PS5Cl, Li7P2S8I, Li10 SnP2S 12 Li 3 .25 Ge 0 .25 P 0 .75 One or more of S4, preferably Li6PS5Cl.

[0090] The binder in the solid electrolyte slurry is, for example, one or more of hydrogenated nitrile butadiene rubber (HNBR), nitrile butadiene rubber (SBR), and polyvinylidene fluoride (PVDF).

[0091] The aforementioned solid-state battery can be prepared by the following method: The solid electrolyte membrane is transferred onto a negative electrode to obtain a solid electrolyte-negative electrode. Then, the positive electrode and the solid electrolyte-negative electrode are stacked sequentially, with the solid electrolyte membrane positioned between the positive and negative electrodes, to obtain a bare cell. The bare cell is placed in an outer packaging shell (aluminum-plastic film) and subjected to vacuum sealing, isostatic pressing, and formation processes to obtain the solid-state battery. The aforementioned vacuum sealing, isostatic pressing, and formation processes are conventional procedures in this field and will not be elaborated upon here.

[0092] Generally, the aforementioned solid-state battery includes a cell and a casing for encapsulating the cell. A solid electrolyte membrane is located between the positive and negative electrodes of the solid-state battery and is assembled within the cell inside the casing. The negative electrode includes a negative electrode sheet, and the positive electrode includes a positive electrode sheet. The cell can be a stacked cell, meaning it is composed of alternating layers of a positive electrode sheet, a solid electrolyte membrane, and a negative electrode sheet; or it can be a wound cell, meaning it is composed of stacked positive electrode sheets, a solid electrolyte membrane, and a negative electrode sheet, which are then wound together.

[0093] Specifically, the positive electrode sheet includes a positive current collector and a positive active material layer located on at least one side surface of the positive current collector. Specifically, the positive active material layer can be provided on one side surface in the thickness direction of the positive current collector, or positive active material layers can be provided on both opposite sides surface in the thickness direction of the positive current collector.

[0094] The positive electrode active material layer includes a positive electrode active material, a solid electrolyte material, a conductive agent, and a binder. In the positive electrode active material layer, the mass percentage of the positive electrode active material can be 40% to 90%, for example, 40%, 50%, 70%, 80%, 85%, 90%, or any combination thereof; the mass percentage of the solid electrolyte material can be 9% to 50%, for example, 10%, 20%, 30%, 40%, 50%, or any combination thereof; the mass fraction of the conductive agent can be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof; and the mass fraction of the binder can be 0.5% to 15%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 8%, 10%, 13%, 15%, or any combination thereof.

[0095] In this embodiment of the invention, the conductive agent in the positive electrode active material layer can be a conventional conductive material in the art. For example, the conductive agent in the positive electrode active material layer may include one or more of conductive carbon black, conductive graphite, carbon nanotubes (CNTs), carbon fibers, graphene, acetylene black, and Ketjen black.

[0096] In this embodiment of the invention, the binder in the positive electrode active material layer can be a conventional binder in the art. For example, the binder in the positive electrode active material layer may include one or more of the following: polyvinylidene fluoride (PVDF), polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, etc.

[0097] The embodiments of the present invention may employ conventional positive current collectors in the art, for example, positive current collectors may include aluminum foil.

[0098] Specifically, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer located on at least one side surface of the negative electrode current collector. Specifically, the negative electrode active material layer can be provided on one side surface of the negative electrode current collector, or negative electrode active material layers can be provided on both opposite sides of the negative electrode current collector in the thickness direction.

[0099] Specifically, the negative electrode active material layer may include a negative electrode active material, a conductive agent, and a binder, all of which can be conventional materials in the art. For example, the negative electrode active material may include one or more of graphite, pure silicon, silicon-carbon, and lithium titanate; the conductive agent may include one or more of conductive carbon black, carbon nanotubes (CNT), acetylene black, graphene, Ketjen black, and carbon fiber; and the binder may include one or more of sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate.

[0100] The embodiments of the present invention may employ conventional negative electrode current collectors in the art, for example, negative electrode current collectors include copper foil.

[0101] This invention also provides a method for preparing the above-mentioned battery, comprising the following steps: coating a positive electrode slurry onto at least one side of a positive electrode current collector, and sequentially subjecting it to a first drying treatment and a first rolling treatment to obtain a positive electrode sheet; coating a negative electrode slurry onto at least one side of a negative electrode current collector, and sequentially subjecting it to a second drying treatment and a second rolling treatment to obtain a negative electrode sheet; assembling the positive electrode sheet and the negative electrode sheet to obtain a battery; and adjusting the pressure of the first rolling treatment and the pressure of the second rolling treatment to ensure that the battery satisfies: 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c ≤0.100.

[0102] The battery prepared by the above-described battery preparation method in this embodiment of the invention satisfies 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c With an ion transport rate ≤ 0.100, this battery has high ion transport rate and electronic conductivity, resulting in high cycle performance and rate performance.

[0103] In detail, in this embodiment of the invention, the positive electrode sheet can be prepared by a coating method. Specifically, the components used to form the positive electrode active material layer, such as the positive electrode active material, solid electrolyte, conductive agent, and binder, can be dispersed in a solvent, such as xylene, to prepare a positive electrode slurry. This slurry is then coated onto the surface of the positive electrode current collector, and after drying, rolling, and other processes, the positive electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing positive electrode sheets using the coating method, and are not particularly limited thereto.

[0104] In practice, a slurry containing positive electrode active material can be prepared at a temperature of 20℃~45℃; conventional coating equipment in the field, such as continuous coating equipment, can be used to coat the slurry containing positive electrode active material onto the surface of the positive electrode current collector.

[0105] In this embodiment of the invention, the negative electrode sheet can be prepared by conventional methods in the art, such as by coating. Specifically, the components used to form the negative electrode active material layer, such as the negative electrode active material, solid electrolyte material, conductive agent, and binder, can be dispersed in a solvent, such as water, to prepare a negative electrode slurry. This slurry is then coated onto the surface of the negative electrode current collector, and after drying, rolling, and other processes, the negative electrode sheet is obtained. The coating, drying, and rolling processes involved are conventional operations for preparing negative electrode sheets using the coating method, and are not particularly limited thereto.

[0106] In practice, a slurry containing negative electrode active material can be prepared at a temperature of 20℃~45℃; conventional coating equipment in the field, such as continuous coating equipment, can be used to coat the slurry containing negative electrode active material onto the surface of the negative electrode current collector.

[0107] In this embodiment of the invention, the battery cell can be packaged using conventional housing materials in the art, such as flexible packaging materials like aluminum-plastic film, but is not limited thereto.

[0108] In some embodiments of the present invention, the pressure of the first rolling process is 350-600 MPa, which is beneficial to better improve the ion transport rate and electronic conductivity of the battery, resulting in higher cycle performance and rate performance. For example, the pressure of the first rolling process is, for example, a range of 400 MPa, 500 MPa, 600 MPa, or any combination thereof.

[0109] In some embodiments, the pressure of the second rolling process is 300-600 MPa, which is beneficial for improving the ion transport rate and electronic conductivity of the battery, resulting in higher cycle performance and rate performance. For example, the pressure of the second rolling process is, for example, a range of 300 MPa, 400 MPa, 500 MPa, 600 MPa, or any combination thereof.

[0110] In this embodiment of the invention, the compaction density and thickness of the positive electrode sheet can be controlled by controlling the pressure of the first rolling process, and the compaction density and thickness of the negative electrode sheet can be controlled by controlling the pressure of the second rolling process.

[0111] This invention also provides a battery pack comprising at least two of the aforementioned batteries, which has advantages corresponding to the aforementioned batteries, and will not be described in detail hereafter.

[0112] Generally, a battery pack includes multiple batteries as individual cells, which are connected to form the battery pack. These batteries can be electrically connected using methods conventional in the art, such as series connection, parallel connection, or a combination of these connection methods, without any particular limitation.

[0113] This invention also provides an electrical device, including the battery or battery pack described above. This electrical device has advantages corresponding to the battery described above, which will not be elaborated further.

[0114] The electrical equipment used in the embodiments of the present invention can be conventional electrical equipment in the art, such as power equipment (e.g., electric vehicles, electric cars), electronic equipment (e.g., mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (e.g., watches, bracelets, VR glasses, etc.), energy storage power stations, etc., and there are no particular limitations on this.

[0115] This invention also provides a battery quality control method, comprising the following steps: detecting the current structural parameters of the positive electrode active material layer and the negative electrode active material layer of the battery; determining whether the current structural parameters meet a preset threshold; wherein the preset threshold is 0.061 ≤ ≤0.100, the current structural parameters are calculated according to the following formula: =CD a ×T a ) / (CD) c ×T c ), 0.061≤ ≤0.100; where, CD c The compaction density of the positive electrode active material layer, expressed in g / cm³. 3 Calculation; CD a The compaction density of the negative electrode active material layer, expressed in g / cm³. 3 Calculation; T c T represents the thickness of the positive electrode active material layer, expressed in μm. a The thickness of the negative electrode active material layer is expressed in μm. Through the above-described battery quality control method, embodiments of the present invention can screen for batteries with higher cycle performance and rate performance.

[0116] In some embodiments of the present invention, the quality control method for the battery further includes: if the current structural parameters of the battery do not meet a preset threshold, performing a first rolling process on the positive electrode and a second rolling process on the negative electrode, until the current structural parameters of the battery meet the preset threshold. Through the above method, the embodiments of the present invention can obtain batteries with higher cycle performance and rate performance.

[0117] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0118] Example 1

[0119] The battery in this embodiment is prepared through the following steps:

[0120] 1) Preparation of the positive electrode: The positive electrode active material LiNi is prepared... 0.8 Co 0.1 Mn 0.1 O2 (NCM811), solid electrolyte Li6PS5Cl, conductive agent carbon black, and binder HNBR are mixed in a mass ratio of 80:20:0.7:1, and xylene solvent is added. A uniform positive electrode slurry is formed under mechanical stirring. The positive electrode slurry is then coated onto aluminum foil and subjected to a first drying treatment (80℃, 10 min). Following this, a first rolling process is performed to obtain the positive electrode sheet at a pressure of 350 MPa.

[0121] 2) Preparation of negative electrode sheet: The negative electrode active material pure silicon, CMC and binder polyacrylic acid are mixed in a mass ratio of 96:1:3, and water is added as a solvent to form a uniform negative electrode slurry in a vacuum mixer; the negative electrode slurry is uniformly coated on copper foil, the solvent is removed and the binder is cured, and a second drying treatment is performed (treatment temperature is 80℃, treatment time is 10min), and then a second rolling treatment is performed to obtain the negative electrode sheet. The pressure of the second rolling treatment is 300 MPa.

[0122] 3) Preparation of solid electrolyte membrane: Solid electrolyte material Li6PS5Cl and binder HNBR are mixed at a mass ratio of 98:2, xylene solvent is added, and a uniform solid electrolyte slurry is formed under the action of a mechanical stirrer. The solid electrolyte slurry is then coated on the substrate and dried to obtain a solid electrolyte membrane.

[0123] 4) Transfer the solid electrolyte membrane onto the negative electrode to obtain a solid electrolyte-negative electrode. Then, stack the positive electrode and solid electrolyte-negative electrode in sequence, with the solid electrolyte membrane located between the positive and negative electrode. The stacked sheets form a bare cell. Place the bare cell in an outer packaging shell (aluminum-plastic film) and perform vacuum sealing, isostatic pressing, and formation processes to obtain the battery.

[0124] In the battery prepared in this embodiment, the compaction density CD of the positive electrode active material layer is... c The compaction density CD of the negative electrode active material layer a Thickness T of the positive electrode active material layer c Thickness T of the negative electrode active material layer a The areal density of the positive electrode active material layer, the areal density of the negative electrode active material layer, the average particle size of the positive electrode active material, and the average particle size of the solid electrolyte material are shown in Table 1.

[0125] Examples 2-17 are basically the same as Example 1, except that the pressure of the first rolling process, the pressure of the second rolling process, the average particle size of the positive electrode active material, and the average particle size of the solid electrolyte material are different from those in Example 1, as detailed in Table 1.

[0126] Example 18

[0127] This embodiment is basically the same as Embodiment 1, except that the positive electrode active material in this embodiment is LiNi. 0.8 Co 0.1 Mn 0.1 Two types of electrolytes are O2 and LiCoO2, and the solid electrolyte material is Li7P2S8I.

[0128] The difference between Comparative Examples 1-4 and Example 1 is that the pressure of the first rolling process, the pressure of the second rolling process, the average particle size of the positive electrode active material, and the average particle size of the solid electrolyte material are different from those in Example 1, as detailed in Table 1.

[0129] In the batteries prepared in the examples and comparative examples, the compaction density CD of the positive electrode active material layer is... c The compaction density CD of the negative electrode active material layer a Thickness T of the positive electrode active material layer c Thickness T of the negative electrode active material layer a The areal density of the positive electrode active material layer (referred to as positive electrode areal density in the table), the areal density of the negative electrode active material layer (referred to as negative electrode areal density in the table), the average particle size of the positive electrode active material (referred to as the first average particle size in the table), and the average particle size of the solid electrolyte material (referred to as the second average particle size in the table) are shown in Table 1.

[0130] Test case

[0131] Average particle size testing of positive electrode active material and solid electrolyte material: a) Disassemble a fully discharged battery to obtain the positive electrode sheet, and then cut any position of the coating area with argon ions to obtain a cross-sectional sample of the positive electrode sheet; b) Place the above positive electrode sheet cross-sectional sample in an SEM for observation. Adjust the SEM voltage and magnification according to actual needs to ensure that enough positive electrode active material and solid electrolyte material in the above sample can be clearly seen and photographed to obtain SEM images; c) The particle size of positive electrode active material and solid electrolyte material can be directly observed through the SEM images; d) Accumulate 10-30 experiments, take different distribution positions of the positive electrode sheet for detection, and statistically analyze the above results to obtain the average particle size of positive electrode active material and solid electrolyte material.

[0132] Thickness T of the positive electrode active material layer c Thickness T of the negative electrode active material layer aTest: After the battery was fully discharged, it was disassembled to separate the positive and negative electrodes. A sample of the positive electrode was taken and then cut into its cross-section using an argon ion beam. The cross-section of the positive electrode was observed using an SEM. The SEM voltage and magnification were adjusted according to actual needs. The thickness of the positive active material layer was measured using the SEM's built-in measuring tools. A total of 20-30 experiments were conducted, and the thickness T of the positive active material layer was statistically determined. c The thickness T of the negative electrode active material layer was tested using the same method. c The test results are shown in Table 1.

[0133] The compaction density CD of the positive electrode active material layer c The compaction density CD of the negative electrode active material layer a The testing method is as follows: The compaction density of the positive electrode active material layer = mass of the positive electrode active material layer / volume of the positive electrode active material layer. The mass of the positive electrode active material layer can be obtained using an electronic balance with an accuracy of 0.01g or higher. The volume of the positive electrode active material layer is the product of the area of ​​the plane perpendicular to the thickness direction and the thickness of the positive electrode active material layer. The testing process for the thickness of the positive electrode active material layer is as described above, and the area of ​​the plane perpendicular to the thickness direction can be obtained using a laser rangefinder. The compaction density of the negative electrode active material layer is also obtained using the above testing method. The test results are shown in Table 1.

[0134] The testing process for the areal density of the positive electrode active material layer may include: taking a sample of the positive electrode active material layer, measuring the total mass m1 of the sample, and the surface area S on one side of the positive electrode active material layer in the thickness direction; then scraping off the positive electrode active material layer from the positive electrode sample, and measuring the mass m2 of the resulting positive electrode current collector. The areal density of the positive electrode active material layer is then calculated as (m1 - m2) / S. The testing method for the areal density of the negative electrode active material layer is similar. The test results are shown in Table 1.

[0135] Battery rate performance testing method: The all-solid-state batteries of the examples and comparative examples were subjected to rate testing. The test voltage range was 2.5-4.2V. The test method is as follows: The batteries of the examples and comparative examples were tested on a battery testing system. First, a 0.1C charge-discharge test was performed, and the discharge specific capacity was calculated as D1. Then, a 0.5C charge-discharge test was performed, and the discharge specific capacity was calculated as D2. The capacity retention rate at 0.5C / 0.1C was D2 / D1×100%, which was recorded as the rate performance. The test results are shown in Table 2.

[0136] Battery cycle performance testing method: The batteries of the examples and comparative examples were subjected to charge-discharge cycle tests at a current of 0.5C. During the cycle, the cycle was terminated when the battery capacity was lower than 80% of the initial discharge capacity. The number of cycles is the cycle life of the battery. The test results (number of cycles) are shown in Table 2.

[0137]

[0138]

[0139] As shown in the table, compared to the comparative example, the embodiments of the present invention achieve the following result by ensuring that the battery satisfies: 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c A value ≤0.100 can effectively improve the rate performance and cycle performance of the battery.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery, characterized in that, It includes a positive electrode sheet and a negative electrode sheet, wherein the positive electrode sheet includes a positive current collector and a positive active material layer present on at least one side of the positive current collector; The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer present on at least one side of the negative electrode current collector; The battery satisfies: 0.061 ≤ (CD a × T a ) / (CD c × T c ) ≤ 0.100; Among them, CD c The compaction density of the positive electrode active material layer is expressed in g / cm³. 3 count; CD a The compaction density of the negative electrode active material layer is expressed in g / cm³. 3 count; T c The thickness of the positive electrode active material layer is expressed in μm. T a The thickness of the negative electrode active material layer is expressed in μm.

2. The battery according to claim 1, characterized in that, The battery satisfies: 0.064 ≤ (CD) a ×T a ) / (CD) c ×T c ≤0.

075.

3. The battery according to claim 1 or 2, characterized in that, 0.9≤CD a ≤1.2, preferably, 0.95≤CD a ≤1.15; And / or, 3.0≤CD c ≤3.4, preferably, 3.1≤CD c ≤3.3; And / or, 10≤T a ≤30, preferably, 15≤T a ≤27; And / or, 90≤T c ≤113, preferably, 95≤T c ≤110.

4. The battery according to any one of claims 1-3, characterized in that, The areal density of the positive electrode active material layer is 270 g / m³. 2 ~385 g / m 2 ; And / or, the areal density of the negative electrode active material layer is 20 g / m³. 2 ~36 g / m 2 .

5. The battery according to any one of claims 1-4, characterized in that, The positive electrode active material layer includes a positive electrode active material and a solid electrolyte material; The positive electrode active material is preferably a layered positive electrode active material; The solid electrolyte material is preferably a sulfide solid electrolyte.

6. The battery according to claim 5, characterized in that, The layered positive electrode active material includes Li a Ni x Co y Mn z M b O 2-c X c One or more of LiCoO2 and LiNiO2; Wherein, M is selected from one or more of Zr, Ti, Sb, Ta, Nb, Y, W, B, Al, Sr, Mo, Mg, and Nd, and X is selected from one or more of F, Cl, and Br, 0.9≤a≤1.1, x+y+z+b+c=1, 0<x<1, 0<y<1, 0<z<1, 0≤b≤0.1, and 0≤c≤0.1; And / or, the sulfide solid electrolyte includes Li3PS4, Li7P3S 11 Li 11 GeP2S 12 Li6PS5Cl, Li7P2S8I, Li 10 SnP2S 12 Li 3 .25 Ge 0 .25 P 0 .75 One or more of S4.

7. The battery according to claim 5 or 6, characterized in that, The average particle size of the positive electrode active material is 4μm~7μm; And / or, the average particle size of the solid electrolyte material is 1 μm to 4 μm.

8. The battery according to any one of claims 1-7, characterized in that, The battery is a solid-state battery, and the solid-state battery further includes a solid electrolyte membrane, which is disposed between the positive electrode and the negative electrode.

9. A method for preparing a battery according to any one of claims 1-8, characterized in that, The process includes the following steps: coating the positive electrode slurry onto at least one side of the positive electrode current collector, and then sequentially performing a first drying process and a first rolling process to obtain a positive electrode sheet; The negative electrode slurry is coated onto at least one side of the negative electrode current collector, and then the negative electrode sheet is obtained after passing through a second drying process and a second rolling process. The battery is obtained by assembling the positive electrode and the negative electrode. By adjusting the pressure of the first and second rolling processes, the battery is made to satisfy: 0.061 ≤ (CD) a ×T a ) / (CD) c ×T c ≤0.

100.

10. The method for preparing a battery according to claim 9, characterized in that, The pressure of the first rolling process is 350 MPa ~ 600 MPa; And / or, the pressure of the second rolling process is 300 MPa to 500 MPa.

11. A battery pack, characterized in that, It includes batteries according to at least two of claims 1-8, or batteries prepared by a method according to at least two of claims 9 or 10.

12. An electrical appliance, characterized in that, It includes the battery according to any one of claims 1-8, or the battery prepared by the method of the battery according to claim 9 or 10, or the battery pack according to claim 11.

13. A method for quality control of a battery, characterized in that, Includes the following steps: The current structural parameters of the positive electrode active material layer and the negative electrode active material layer of the battery are detected; Determine whether the current structural parameters meet the preset threshold; Wherein, the preset threshold is 0.061≤ ≤0.100, the current structural parameter is calculated according to the following formula: =(CD) a ×T a ) / (CD c ×T c ),0.061≤ ≤0.100; in, ; CD c The compaction density of the positive electrode active material layer is expressed in g / cm³. 3 count; CD a The compaction density of the negative electrode active material layer is expressed in g / cm³. 3 count; T c The thickness of the positive electrode active material layer is expressed in μm. T a The thickness of the negative electrode active material layer is expressed in μm.

14. The battery quality control method according to claim 13, characterized in that, Also includes: If the current structural parameters of the battery do not meet the preset threshold, the positive electrode is subjected to a first rolling process, and the negative electrode is subjected to a second rolling process until the current structural parameters of the battery meet the preset threshold.

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