A high-energy-density electrode slurry for lithium-ion batteries, a lithium-ion battery, and a preparation method thereof.

Abstract

This invention relates to the field of electrode slurry technology, and more particularly to a high-energy-density lithium-ion battery electrode slurry, a lithium-ion battery, and a preparation method thereof. The method includes: adding a conductive agent and a nonionic polymeric dispersant to a first solvent for a first dispersion treatment to obtain a pre-dispersed slurry; the nonionic polymeric dispersant includes poly(2-ethyl-2-oxazoline); adding an active material to the pre-dispersed slurry for a second dispersion treatment to obtain a mixed slurry; dissolving a binder in a second solvent to obtain a binder solution; mixing the mixed slurry and the binder solution and stirring to obtain the electrode slurry; wherein the mass of the nonionic polymeric dispersant accounts for 0.15% to 0.40% of the total mass of the solute in the electrode slurry; this method can effectively reduce and maintain the viscosity of the electrode slurry, giving the electrode slurry excellent rheological properties and storage stability.

Description

Technical Field

[0001] This invention relates to the field of electrode slurry technology, and in particular to a high-energy-density lithium-ion battery electrode slurry, a lithium-ion battery, and a preparation method thereof. Background Technology

[0002] As a core technology in the current energy storage and power battery fields, the performance optimization of lithium-ion batteries has always been a key focus of the industry. With the rapid development of mobile electronic devices and the new energy vehicle industry, the market has placed higher demands on the energy density of lithium-ion batteries, making the development of lithium-ion batteries with high specific energy characteristics an important research direction.

[0003] In the electrode fabrication process of lithium-ion batteries, the preparation of electrode slurry is one of the key steps. The rheological properties, dispersion uniformity, and stability of the slurry directly affect the microstructure, pore structure, and component distribution of the coated electrode, thus determining the battery's capacity and cycle performance. Especially for lithium-ion batteries designed for high-energy-density applications, the electrodes typically employ a larger active material loading, resulting in a significant increase in electrode thickness. In this case, the migration path of lithium ions within the electrode is lengthened, and the transport resistance increases. Therefore, it is necessary to further improve the continuity of the conductive network and the consistency of the active component distribution in the electrode, which places more stringent requirements on the electrode slurry preparation process.

[0004] Therefore, in response to the development needs of high-energy-density lithium-ion batteries, optimizing electrode slurry to improve the microstructure and electrochemical performance of the electrode is of great significance for improving battery capacity and cycle performance and promoting technological progress in related industries.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] This invention provides an electrode slurry for high-energy-density lithium-ion batteries, a lithium-ion battery, and a preparation method thereof, which can effectively solve the problems in the background art.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing a high-energy-density lithium-ion battery electrode slurry, the method comprising: A conductive agent and a nonionic polymeric dispersant are added to a first solvent for a first dispersion treatment to obtain a pre-dispersed slurry; the nonionic polymeric dispersant includes poly(2-ethyl-2-oxazoline); The active substance is added to the pre-dispersed slurry for a second dispersion treatment to obtain a mixed slurry; The adhesive is dissolved in a second solvent to obtain an adhesive solution; The mixed slurry is mixed with the binder solution and stirred to obtain an electrode slurry; wherein the mass of the nonionic polymeric dispersant accounts for 0.15% to 0.40% of the total mass of the solute in the electrode slurry.

[0008] Furthermore, the number-average molecular weight of the poly(2-ethyl-2-oxazoline) is 20,000 g / mol to 100,000 g / mol.

[0009] Further, the first dispersion treatment is a first high-shear dispersion treatment, wherein the rotation speed of the first high-shear dispersion treatment is 100 rpm to 3000 rpm, and the treatment time is 15 min to 60 min; and / or, The second dispersion treatment is a second high-shear dispersion treatment, wherein the rotation speed of the second high-shear dispersion treatment is 100 rpm to 3000 rpm, and the treatment time is 15 min to 60 min; and / or, The stirring process is vacuum low-speed stirring, with a stirring speed of 20 rpm to 300 rpm and a stirring time of 120 min to 500 min.

[0010] Furthermore, the solid content of the electrode slurry is 40%~75%; and / or, In the electrode slurry, the mass ratio of the active material, the conductive agent and the binder is (90~96):(2~5):(2~5).

[0011] Furthermore, the active material includes a high-nickel ternary material; In the step of preparing the pre-dispersed slurry, oxalic acid is also added to the first solvent.

[0012] Furthermore, the mass ratio of oxalic acid to poly(2-ethyl-2-oxazoline) is (1~3):1.

[0013] A second aspect of the present invention provides an electrode slurry for high-energy-density lithium-ion batteries, which is prepared by the above-described method for preparing electrode slurry for high-energy-density lithium-ion batteries.

[0014] A third aspect of the present invention provides a method for preparing a high-energy-density lithium-ion battery, the method comprising: A positive electrode slurry is coated on at least one side surface of the positive electrode current collector along the thickness direction, and after drying, a positive electrode sheet is obtained. The negative electrode slurry is coated on at least one side surface of the negative electrode current collector along the thickness direction, and after drying, a negative electrode sheet is obtained. Both the positive electrode slurry and the negative electrode slurry are prepared using the above-mentioned method for preparing electrode slurries for high-energy-density lithium-ion batteries; A separator is placed between the positive electrode and the negative electrode to assemble an electrode assembly; after packaging the electrode assembly, an electrolyte is injected, and then the assembly undergoes formation and capacity testing to obtain the high-energy-density lithium-ion battery.

[0015] Furthermore, the viscosity of the positive electrode slurry is 4000 mPa·s to 8000 mPa·s, and the fineness is ≤20 μm; and / or, The viscosity of the negative electrode slurry is 2700 mPa·s to 4500 mPa·s, and the fineness is ≤40 μm.

[0016] The fourth aspect of this invention provides a high-energy-density lithium-ion battery, which is prepared by the above-described method for preparing a high-energy-density lithium-ion battery.

[0017] The technical solution of this invention can achieve the following technical effects: This invention optimizes the feeding sequence and dispersion process, and utilizes the steric hindrance effect of specific types and appropriate amounts of nonionic polymeric dispersants to achieve efficient material dispersion. This effectively reduces and maintains the viscosity of the electrode slurry, giving it excellent rheological properties and storage stability. When the electrode slurry prepared by this invention is applied to battery manufacturing, even with a thick coating, the conductive agent and active material particles in the slurry maintain a good and uniform dispersion during coating and drying. The resulting electrode has a uniform microstructure of active coating, and the conductive agent forms a complete three-dimensional conductive network. This reduces electrode resistance, promotes the capacity utilization of active materials, and ultimately improves the battery's specific energy and cycle life, resulting in a high-energy-density lithium-ion battery. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a method for preparing a high-energy-density lithium-ion battery electrode slurry according to this application. Figure 2 This is a schematic flowchart of a method for preparing a high-energy-density lithium-ion battery according to this application; Figure 3 The particle size distribution diagrams are for the positive electrode slurries prepared in Example 1 and Comparative Examples 1 to 4. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application.

[0023] Unless otherwise specified, the techniques or conditions described in the following embodiments are generally performed in accordance with conventional techniques or conditions described in the literature in this field, or in accordance with the product manual and the manufacturer's recommendations. All numerical ranges in the following embodiments include endpoint values.

[0024] Electrode slurries are mainly composed of active materials, conductive agents, binders, and solvents. Currently, in industrial production, all materials are typically mixed together in a solvent to prepare the electrode slurry. For example, all dry powder materials (active materials, conductive agents, and binders) are simultaneously or sequentially added to the solvent and subjected to prolonged, high-intensity mechanical stirring to achieve uniform mixing. However, this traditional process limits the preparation of high-performance electrodes. Conductive agents (especially nanoscale carbon black and carbon nanotubes) have extremely large specific surface areas and high surface energies, making them prone to forming agglomerated networks in solvents. Conventional shear forces are insufficient to completely break them apart and achieve uniform nanoscale dispersion. Simultaneously, active material particles also exhibit soft agglomeration. This results in uneven distribution of the conductive agent in the final electrode slurry, preventing the formation of a complete and continuous coating layer on the surface of the active material. Consequently, the internal electronic conductivity network of the electrode prepared using electrode slurry has shortcomings and breaks. Furthermore, due to the uneven and incomplete dispersion of materials, the electrode slurry system is in a thermodynamically unstable state. During processes such as settling, conveying, and coating, particle sedimentation and re-agglomeration easily occur, directly affecting the consistency of the electrode slurry coating surface density, the uniformity of electrode quality, and the stability of production batches. To achieve a certain dispersion effect, it is often necessary to extend the stirring time or increase the stirring intensity. This not only leads to increased energy consumption and reduced production efficiency, but the violent mechanical action may also damage the crystal structure of the active material or introduce metallic impurities from the equipment, posing a potential threat to the long-term performance of the battery. In addition, in traditional processes, binders, conductive agents, and active materials are added almost simultaneously. The polymer chains of the binder tend to prematurely encapsulate the active material particles and compete with the conductive agent for adsorption, thus interfering with the comprehensive spreading and adhesion of the conductive agent on the surface of the active material. The poor dispersion of the conductive agent and active material in the slurry results in poor slurry stability, ultimately making it difficult to construct an efficient conductive-ion transport path in the electrode, leading to poor specific energy and cycle performance of the battery.

[0025] Based on this, this application provides a method for preparing a high-energy-density lithium-ion battery electrode slurry. Please refer to [link / reference]. Figure 1 The method for preparing high-energy-density lithium-ion battery electrode slurry provided in this application includes the following steps: S101: A conductive agent and a nonionic polymeric dispersant are added to a first solvent for a first dispersion treatment to obtain a pre-dispersed slurry; the nonionic polymeric dispersant includes poly(2-ethyl-2-oxazoline); S102: Add the active material to the pre-dispersed slurry and perform a second dispersion treatment to obtain a mixed slurry; S103: Dissolve the adhesive in a second solvent to obtain an adhesive solution; S104: Mix the mixed slurry with the binder solution and stir to obtain the electrode slurry; wherein the mass of the nonionic polymeric dispersant accounts for 0.15%~0.40% of the total mass of the solute in the electrode slurry.

[0026] In this embodiment, in step S101, a conductive agent and a nonionic polymeric dispersant are added to a first solvent. With the assistance of the nonionic polymeric dispersant, the first dispersion treatment effectively breaks the agglomeration of the conductive agent, forming a pre-dispersed slurry with a uniformly dispersed conductive agent. In step S102, an active substance is added to the pre-dispersed slurry. Through a second dispersion treatment, the active substance is fully dispersed in the pre-dispersed slurry. The nonionic polymeric dispersant can exert a steric hindrance effect to prevent the agglomeration of active substance particles, ensuring a stable dispersion effect. The conductive agent, which is well dispersed in the slurry, can fully coat the surface of the active material particles and be evenly distributed between the particles, which can further avoid the problems of agglomeration and uneven dispersion of the conductive agent. In step S103, the binder is first dissolved in the second solvent to obtain the binder solution. In step S104, the mixed slurry is then mixed with the binder solution to obtain the electrode slurry. This can prevent the polymer chains of the binder from prematurely coating the active material particles or competing with the non-ionic polymeric dispersant for adsorption, thereby avoiding affecting the coating and uniform dispersion of the conductive agent on the surface of the active material particles. In this embodiment, the nonionic polymeric dispersant poly(2-ethyl-2-oxazoline) can ensure the coating and uniform dispersion of the conductive agent on the surface of the active material particles due to its excellent steric hindrance effect, maintaining the dispersion uniformity and stability of the electrode slurry. Furthermore, poly(2-ethyl-2-oxazoline) exhibits excellent dispersion performance in both aqueous and oily systems, making it suitable for the preparation of both oily positive electrode slurries and aqueous negative electrode slurries, thus possessing wide applicability and suitability for large-scale production. However, when the amount of nonionic polymeric dispersant added is too low, it is difficult to achieve effective stabilization. Regarding the dispersion effect, when the amount of nonionic polymeric dispersant added is too high, self-aggregation is likely to occur, which will increase the viscosity of the slurry, reduce the dispersion stability, and make the conductive agent and active material prone to re-aggregate, that is, the storage stability of the electrode slurry is poor. Therefore, in the embodiments of this application, the mass of nonionic polymeric dispersant is controlled to account for 0.15% to 0.40% of the total mass of solute in the electrode slurry. This not only can a low initial viscosity electrode slurry be obtained, but also the uniformity and stability of the electrode slurry can be maintained, which is beneficial to obtaining an electrode slurry with low viscosity, high stability, and suitable for high-speed coating.

[0027] It should be noted that although the steps in the flowchart above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Moreover, at least some of the steps in the flowchart above may include multiple steps or stages, and these steps or stages are not necessarily completed at the same time, nor are they necessarily performed sequentially.

[0028] For example, the mass of the nonionic polymeric dispersant can be 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40% of the total mass of the solute in the electrode slurry, or any value between any two of the above ranges.

[0029] In some embodiments, the nonionic polymeric dispersant may be poly(2-ethyl-2-oxazoline).

[0030] When the molecular weight of poly(2-ethyl-2-oxazoline) is too low, its adsorption and steric hindrance effects are limited, thus restricting its dispersion effect on conductive agents and active substances. When the molecular weight of poly(2-ethyl-2-oxazoline) is too high, its long molecular chains are prone to entanglement and adhesion, which affects the dispersion effect and dispersion stability of conductive agents and active substances. Therefore, in some embodiments, the number average molecular weight of poly(2-ethyl-2-oxazoline) can be 20,000 g / mol to 100,000 g / mol, which can better ensure the dispersion effect and dispersion stability of poly(2-ethyl-2-oxazoline) on conductive agents and active substances.

[0031] In step S101, a conductive agent and a nonionic polymeric dispersant are added to a first solvent for a first dispersion treatment to obtain a pre-dispersed slurry.

[0032] For example, the conductive agent can be at least one of conductive carbon black, carbon nanotubes, and graphene. In a specific example, the conductive agent can be conductive carbon black and carbon nanotubes.

[0033] For example, the first solvent can be water or an organic solvent; specifically, when preparing a positive electrode slurry, the first solvent can be an organic solvent, such as N-methylpyrrolidone (NMP); when preparing a negative electrode slurry, the first solvent can be water, such as deionized water.

[0034] In some embodiments, the first dispersion treatment can be a first high-shear dispersion treatment, the rotation speed of the first high-shear dispersion treatment can be 100 rpm to 3000 rpm, for example, 100 rpm, 500 rpm, 1000 rpm, 1500 rpm, 2000 rpm, 2500 rpm, 3000 rpm or any value between any two of the above ranges, and the processing time can be 15 min to 60 min, for example, 15 min, 30 min, 45 min, 60 min or any value between any two of the above ranges.

[0035] With the aid of nonionic polymeric dispersants, high-shear dispersion treatment is specifically applied to conductive agents, which can effectively break down the agglomeration network of the conductive agents, thereby forming a stable and uniform conductive agent nano-dispersion slurry, i.e., a pre-dispersion slurry. This helps ensure the uniform dispersion of the conductive agent in the final electrode slurry, while also ensuring processing efficiency.

[0036] To ensure the conductivity of the electrode slurry, the conductive agent can be a nanoscale conductive agent, such as nanoscale conductive carbon black, carbon nanotubes, or graphene. Nanoscale conductive agents possess excellent conductivity and a large specific surface area, which is beneficial for forming a more uniform and complete conductive network in the electrode, thereby reducing the electrode resistance and improving battery performance. However, these nanoscale conductive agents have extremely large specific surface areas and high surface energies, making them prone to agglomeration in solvents. Therefore, for nanoscale conductive agents, high-shear dispersion treatment can better ensure the dispersion effect of the conductive agent and form a stable and uniform pre-dispersed slurry.

[0037] In step S102, the active substance is added to the pre-dispersed slurry for a second dispersion treatment to obtain a mixed slurry.

[0038] The active material here can be either a positive electrode active material or a negative electrode active material. When preparing the positive electrode slurry, the active material is a positive electrode active material, specifically, at least one of lithium iron phosphate, ternary materials, and lithium manganese iron phosphate. When preparing the negative electrode slurry, the active material is a negative electrode active material, specifically, at least one of graphite, soft carbon, hard carbon, silicon-carbon composite materials, and silicon.

[0039] In some embodiments, the active material may include a high-nickel ternary material.

[0040] High-nickel ternary materials, as positive electrode active materials, possess higher specific capacity, which is beneficial for fabricating high-energy-density lithium-ion batteries. The surface of high-nickel ternary material particles typically contains free Ni. 2+ / Ni 3+When oxalic acid reacts with transition metal ions, the dicarboxyl groups in the oxalic acid molecule can chelate with these metal ions, forming a stable chelate layer on the surface of high-nickel ternary material particles. This chelate layer reduces the electrostatic attraction between particles, decreases the agglomeration and precipitation of high-nickel ternary materials in the slurry, and prevents abnormal increases in slurry viscosity. Simultaneously, the amide bonds on the poly(2-ethyl-2-oxazoline) molecular chain can adsorb onto the surface of the oxalic acid chelate layer on the high-nickel ternary material particles through hydrogen bonding, enhancing the adsorption strength of poly(2-ethyl-2-oxazoline) on the particle surface and forming a denser steric hindrance layer. This better physically blocks collisions and agglomeration of adjacent particles, thus better maintaining the dispersion uniformity of the final electrode slurry and further improving its long-term storage stability. In summary, oxalic acid can synergistically enhance the uniformity and storage stability of the prepared electrode slurry by working with the nonionic polymeric dispersant poly(2-ethyl-2-oxazoline).

[0041] Furthermore, since the surface of high-nickel ternary materials usually has residual alkali (Li2CO3, LiOH), oxalic acid can neutralize the residual alkali, suppress the gel effect caused by local alkalinity during slurry preparation, reduce the irreversible side reaction between residual alkali and binders (such as polyvinylidene fluoride) added in subsequent steps, thereby further ensuring the stability and rheological properties of the slurry, and better ensuring the capacity of high-nickel ternary materials, thereby further improving the specific energy of the battery.

[0042] In the above embodiments, the addition of oxalic acid in step S101, with the assistance of a nonionic polymeric dispersant, allows the oxalic acid to be evenly dispersed in the pre-dispersed slurry. Thus, in step S102, when the active material, including the high-nickel ternary material, is added to the pre-dispersed slurry, the oxalic acid can better form a stable chelating layer on the surface of the high-nickel ternary material particles, thereby further enhancing the adsorption strength of poly(2-ethyl-2-oxazoline) on the surface of the high-nickel ternary material particles and more quickly and thoroughly neutralizing residual alkali on the surface of the high-nickel ternary material. Of course, this application does not exclude the possibility of adding oxalic acid and the active material together to the pre-dispersed slurry in step S102.

[0043] It is understandable that when the mass ratio of oxalic acid to poly(2-ethyl-2-oxazoline) is too small, the amount of oxalic acid added is relatively small, limiting its effect on enhancing the dispersion of poly(2-ethyl-2-oxazoline) and its neutralizing effect on residual alkali on the surface of high-nickel ternary materials. When the mass ratio of oxalic acid to poly(2-ethyl-2-oxazoline) is too large, the amount of oxalic acid added is relatively large, which may form an excessively thick and uneven chelating layer on the surface of high-nickel ternary materials, thus affecting the stability of the dispersion system. Moreover, excessive oxalic acid addition will lead to a reduction in the amount of at least one of the active material, conductive agent, and binder, which will also affect one or more of the specific energy, conductivity, and structural stability of the electrode sheet prepared using the electrode paste. Therefore, in some embodiments, the mass ratio of oxalic acid to poly(2-ethyl-2-oxazoline) can be 1 to 3:1, which is beneficial to better ensure the synergistic effect of oxalic acid and poly(2-ethyl-2-oxazoline), thereby further improving the uniformity and storage stability of the final electrode paste.

[0044] In some embodiments, the second dispersion treatment can be a second high-shear dispersion treatment. The rotation speed of the second high-shear dispersion treatment is 100 rpm to 3000 rpm, and the treatment time is 15 min to 60 min. The high-shear dispersion treatment helps to ensure the full dispersion of the active material. Under the steric hindrance effect of the nonionic polymeric dispersant, the active material particles are dispersed stably. The conductive agent, which is well dispersed in the pre-dispersed slurry, can fully coat the surface of the active material particles and be evenly distributed between the particles, thereby further avoiding the problems of agglomeration and uneven dispersion of the conductive agent itself. This can form a uniform and stable mixed slurry, which helps to ensure the uniform dispersion of the conductive agent and the active material in the final electrode slurry.

[0045] In step S103, the adhesive is dissolved in a second solvent to obtain an adhesive solution.

[0046] For example, the binder can be at least one of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR); when preparing the positive electrode slurry, the binder can be PVDF; when preparing the negative electrode slurry, the binder can be CMC and SBR. The type of the second solvent can be understood with reference to the type of the first solvent mentioned above, and will not be repeated here.

[0047] In some embodiments, the mass fraction of the adhesive solution can be 5% to 7%, which is beneficial for the uniform mixing of the adhesive solution and the mixed slurry in the subsequent process.

[0048] In step S104, the mixed slurry and the binder liquid are mixed and stirred to obtain the electrode slurry.

[0049] In some embodiments, the stirring process can be vacuum low-speed stirring, with a stirring speed of 20 rpm to 300 rpm and a stirring time of 120 min to 500 min.

[0050] By stirring at low speed, it is possible to ensure that the binder solution and the mixed slurry are mixed evenly, while avoiding the disruption of the uniform dispersion of the conductive agent already formed in the mixed slurry. Moreover, stirring at low speed under vacuum can effectively remove air bubbles in the slurry, further ensuring the uniform dispersion of the material and preventing free radical oxidation reactions between oxygen in the air and the binder, which would affect the bonding and mechanical properties of the binder. In particular, during the high-shear dispersion treatment in the previous step, air is entrained during high-speed shearing, forming microbubbles in the slurry. If these bubbles are not removed, they will affect the coating effect of the electrode slurry and reduce the quality and performance of the resulting electrode sheet.

[0051] In some embodiments, the solid content of the electrode slurry obtained in step S104 can be 40% to 75%, which is beneficial to control the viscosity of the electrode slurry within a suitable range, as well as to maintain the uniformity and stability of the electrode slurry, making the electrode slurry suitable for high-speed coating.

[0052] In some embodiments, the mass ratio of active material, conductive agent and binder in the electrode slurry obtained in step S104 can be (90~96):(2~5):(2~5), which is beneficial to ensure the capacity performance, conductivity and rheological properties of the electrode slurry, thereby improving the specific energy, conductivity and structural stability of the electrode sheet made using the electrode slurry.

[0053] This application also provides a high-energy-density lithium-ion battery electrode slurry, which is prepared by the preparation method of the high-energy-density lithium-ion battery electrode slurry in any of the foregoing embodiments.

[0054] It is understood that the beneficial effects of the electrode slurry prepared by the method for preparing high-energy-density lithium-ion battery electrode slurry described in any of the foregoing embodiments are also applicable to the high-energy-density lithium-ion battery electrode slurry in the embodiments of this application.

[0055] This application also provides a method for preparing a high-energy-density lithium-ion battery. Please refer to [link / reference]. Figure 2 The method for preparing a high-energy-density lithium-ion battery provided in this application includes the following steps: S201: The positive electrode slurry is coated on at least one side surface of the positive electrode current collector along the thickness direction, and after drying, a positive electrode sheet is obtained; the positive electrode slurry is prepared by the method for preparing high-energy-density lithium-ion battery electrode slurry in any of the preceding embodiments; S202: The negative electrode slurry is coated on at least one side surface of the negative electrode current collector along the thickness direction, and after drying, a negative electrode sheet is obtained; the negative electrode slurry is prepared by the method for preparing high-energy-density lithium-ion battery electrode slurry in any of the foregoing embodiments; S203: The separator is placed between the positive and negative electrode plates to assemble an electrode assembly; after packaging the electrode assembly, electrolyte is injected, and then formation and capacity testing are performed to obtain a high-energy-density lithium-ion battery.

[0056] In this embodiment, the positive electrode slurry and negative electrode slurry in steps S201 and S202 are prepared using the high-energy-density lithium-ion battery electrode slurry preparation method described in any of the preceding embodiments. Therefore, both the positive electrode slurry and the negative electrode slurry have excellent rheological properties and storage stability. During the coating and drying process of the positive electrode slurry and the negative electrode slurry, even with a relatively thick coating, the conductive agent and active material particles in the slurry can maintain a good uniform dispersion state. This results in a uniform microstructure of the active coating in the high-load positive / negative electrode sheet, and the conductive agent can form a complete three-dimensional conductive network, thereby reducing the electrode resistance, promoting the capacity utilization of the active material, and thus improving the specific energy and cycle life of the battery.

[0057] It should be noted that although the steps in the flowchart above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Moreover, at least some of the steps in the flowchart above may include multiple steps or stages, and these steps or stages are not necessarily completed at the same time, nor are they necessarily performed sequentially.

[0058] It is understood that when preparing the positive electrode slurry or negative electrode slurry in the embodiments of this application using the preparation method of high-energy-density lithium-ion battery electrode slurry in any of the foregoing embodiments, the conductive agent, active material, binder, first solvent and second solvent can be selected according to the type of slurry. For details, please refer to the foregoing embodiments, which will not be repeated here.

[0059] In some embodiments, the positive current collector in step S201 can be aluminum foil.

[0060] In some embodiments, the active material used to prepare the cathode slurry can be a ternary material (specifically, for example, a high-nickel ternary material), which is beneficial to improving the specific energy of the obtained high-energy-density lithium-ion battery.

[0061] In some embodiments, the viscosity of the positive electrode slurry in step S201 is 4000 mPa·s to 8000 mPa·s, and the fineness is ≤20 μm, which is beneficial to ensuring the stability and coating performance of the positive electrode slurry.

[0062] In actual preparation processes, the positive electrode slurry can be coated on one side of the positive electrode current collector along its thickness direction, or it can be coated on both sides of the positive electrode current collector along its thickness direction. After drying, the double-sided loading of the positive electrode slurry on the positive electrode current collector (also known as the loading of the positive electrode active material layer) can be 40 mg / cm³. 2 ~56mg / cm 2 This is beneficial for ensuring the specific energy of the high-energy-density lithium-ion batteries produced.

[0063] In some embodiments, the negative current collector in step S202 may be a copper foil.

[0064] In some embodiments, the active material used to prepare the negative electrode slurry can be a silicon-carbon composite material, which is beneficial to improving the specific energy of the obtained high-energy-density lithium-ion battery. Furthermore, the silicon mass ratio in the silicon-carbon composite material is 3% to 30%, which is beneficial to achieving both high specific energy and low expansion of the negative electrode sheet, thereby achieving both high specific energy and high cycle performance of the high-energy-density lithium-ion battery.

[0065] In some embodiments, the viscosity of the negative electrode slurry in step S202 is 2700 mPa·s to 4500 mPa·s, and the fineness is ≤40 μm, which is beneficial to ensuring the stability and coating performance of the negative electrode slurry.

[0066] In actual preparation processes, the negative electrode slurry can be coated on one side of the negative electrode current collector along its thickness direction, or it can be coated on both sides of the negative electrode current collector along its thickness direction. After drying, the double-sided loading of the negative electrode slurry on the negative electrode current collector (also known as the loading of the negative electrode active material layer) can be 16 mg / cm³. 2 ~30mg / cm 2 This is beneficial for ensuring the specific energy of the high-energy-density lithium-ion batteries produced.

[0067] In step S203, the separator is placed between the positive electrode and the negative electrode to assemble an electrode assembly; after packaging the electrode assembly, electrolyte is injected, and then formation and capacity testing are performed to obtain a high-energy-density lithium-ion battery.

[0068] In actual manufacturing processes, electrode assemblies can be assembled using either a winding process or a stacking process. In the winding process, the separator, negative electrode, separator, and positive electrode can be stacked in sequence and then wound to obtain the electrode assembly. In the stacking process, the separator, negative electrode, separator, and positive electrode can be stacked sequentially to the required number of layers to obtain the electrode assembly.

[0069] In some embodiments, the diaphragm may be a polyethylene (PE) membrane with an alumina coating on both sides, or it may be a PE membrane or a polypropylene (PP) membrane.

[0070] In some embodiments, the electrolyte may include lithium salt, carbonate solvent and additives; based on the mass percentage of the electrolyte (100%), the lithium salt may be 14% to 18%, the carbonate solvent may be 60% to 70%, and the additives may be 8% to 14%.

[0071] For example, the lithium salt can be lithium hexafluorophosphate; the carbonate solvent can be a mixture of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, and diethyl carbonate in a mass ratio of (7~18):(6~14):(23~24):(10~30). The additive can be a mixture of 1,3-propanesulfonyl lactone, fluoroethylene carbonate, lithium difluorooxalate borate, tris(trimethylsilane)borate, 1,3-propenesulfonyl lactone, tris(trimethylsilane)phosphate, ethylene sulfate, and lithium bis(difluorosulfonylimide) in a mass ratio of (0~2):(5~10):(0.5~1):(1~2):(0~2):(0~3):(0.5~1):(0~1). The electrolyte of this composition can effectively suppress the expansion of silicon-carbon composite materials and improve the cycle performance of the battery.

[0072] In some embodiments, the electrode assembly can be packaged using an aluminum-plastic film. The packaged battery can be referred to as a pouch battery.

[0073] In the actual preparation process, step S203, including electrolyte injection, formation, and volume separation, may include: The battery cell is injected with electrolyte at a rate of 2g / Ah to 3g / Ah; allowed to stand for 30 minutes; then vacuumed for the first pre-sealing and allowed to stand at room temperature for 24 hours; followed by the first hot-pressing treatment at a pressure of 0.1MPa to 0.4MPa, a temperature of 35℃ to 80℃, and a time of 15 to 70 minutes; allowed to stand for 30 minutes; then undergoing the first pre-formation treatment with a charging current of 0.01C to 0.1C, a charging time of 150 to 270 minutes, and a final voltage of 3.4V to 3.7V; after the first pre-formation treatment, the cell is cut open at the first sealing position, vacuumed, and then pre-sealed a second time; allowed to stand at room temperature for 24 hours; then undergoing the second hot-pressing treatment at a pressure of 0.1MPa to 0.4MPa, a temperature of 35℃ to 80℃, and a time of 15 to 70 minutes; allowed to stand for 30 minutes; and finally undergoing the first main formation treatment. The charging current is 0.2C~0.4C, the charging time is 150min~300min, and the ending voltage is 4.1V~4.3V; after standing for 10min, constant current discharge is performed with a discharge current of 0.1C~0.4C and an ending voltage of 2.4V~2.7V; after standing for 10min, charging is performed at 0.2C~0.4C, and the ending voltage is 3.4V~3.7V; after completion, the battery is cut open at the second sealing position, vacuumed, and pre-sealed for the third time; after standing at room temperature for 24h, the battery is subjected to a third hot-pressing treatment with a pressure of 0.1MPa~0.4MPa, a hot-pressing temperature of 35℃~80℃, and a hot-pressing time of 15min~70min; after standing at room temperature for 24h, the battery is placed in an oven at 40℃~55℃ and left to stand for 1~3 days for aging treatment; finally, the battery is classified and trimmed to obtain a high-energy-density lithium-ion rechargeable soft-pack battery.

[0074] In this embodiment, the formation process of pre-formation, main formation, aging and three-stage hot pressing can form a stable solid electrolyte interphase (SEI) film, which can significantly enhance the consistency of the battery, thereby improving the specific energy and cycle stability of the battery.

[0075] In some embodiments, the N / P value of the high-energy-density lithium-ion battery obtained in step S203 can be 1.05-1.12.

[0076] The N / P value here refers to the ratio of the negative electrode capacity to the positive electrode capacity. In actual preparation processes, the N / P value can be adjusted by the type of positive and negative electrode active materials and the loading of the positive and negative electrode active material layers.

[0077] This application also provides a high-energy-density lithium-ion battery, which is prepared using the preparation method of the high-energy-density lithium-ion battery in any of the foregoing embodiments.

[0078] It is understood that the beneficial effects of the high-energy-density lithium-ion battery prepared by the preparation method of the high-energy-density lithium-ion battery described in any of the foregoing embodiments are also applicable to the high-energy-density lithium-ion batteries in the embodiments of this application.

[0079] The technical solution of this application will be further described below with reference to several embodiments and comparative examples.

[0080] Example 1:

[0081] The preparation method of the high-energy-density lithium-ion battery positive electrode slurry in this embodiment includes the following steps: Step S101: Weigh 1.00g of conductive carbon black SP, 0.05g of poly(2-ethyl-2-oxazoline) (PEOX) with a number average molecular weight of 50000g / mol, and 14.22g of NMP (first solvent), and place them in a planetary mixing tank; disperse them at high speed by shearing at 300rpm for 30min to obtain a uniform conductive agent predispersed slurry (predispersed slurry). Step S102: Add 18.00g of high-nickel ternary material LiNi to the pre-dispersed slurry obtained in step S101. 0.8 Co 0.1 Mn 0.1 O2; Adjust the rotation speed to 600 rpm and continue high-speed shear dispersion for 30 min to obtain uniform LiNi. 0.8 Co 0.1 Mn 0.1 O2 / SP mixed slurry; Step S103: Weigh 0.95g of PVDF and dissolve it in 14.88g of NMP (second solvent), and stir magnetically until completely dissolved to obtain a 6wt% adhesive solution; Step S104: The binder solution obtained in step S103 is slowly poured into the mixed slurry obtained in step S102; the planetary mixer speed is reduced to 50 rpm, and the mixture is gently stirred for 240 minutes to obtain a positive electrode slurry with a solid content of 40%; in this embodiment, LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, PVDF, and PEOX is 90:5:4.75:0.25, meaning that the mass of PEOX accounts for 0.25% of the total mass of solutes in the electrode slurry.

[0082] Example 2:

[0083] The difference between the preparation method of the high-energy-density lithium-ion battery positive electrode slurry in this embodiment and that in Example 1 is: LiNi 0.8 Co 0.1 Mn 0.1The mass ratio of O2, SP, PVDF, and PEOX is adjusted to 90:5:4.85:0.15, which means that the mass of PEOX in the electrode slurry is adjusted to 0.15% of the total mass of solutes.

[0084] Example 3:

[0085] The difference between the preparation method of the high-energy-density lithium-ion battery positive electrode slurry in this embodiment and that in Example 1 is: LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, PVDF, and PEOX is adjusted to 90:5:4.6:0.4, which means that the mass of PEOX accounts for 0.4% of the total mass of solutes in the electrode slurry.

[0086] Example 4:

[0087] The difference between the preparation method of the high-energy-density lithium-ion battery positive electrode slurry in this embodiment and that in Example 1 is: In step S101, oxalic acid is also added to the first solvent NMP, and LiNi is... 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, PVDF, oxalic acid, and PEOX is set to 95:2.5:2:0.25:0.25, which means the mass ratio of oxalic acid to PEOX is 1:1.

[0088] Example 5:

[0089] The difference between the preparation method of the high-energy-density lithium-ion battery positive electrode slurry in this embodiment and that in Example 1 is: In step S101, oxalic acid is also added to the first solvent NMP, and LiNi is... 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, PVDF, oxalic acid, and PEOX is set to 95:2.5:1.75:0.50:0.25, which means the mass ratio of oxalic acid to PEOX is 2:1.

[0090] Example 6:

[0091] The difference between the preparation method of the high-energy-density lithium-ion battery positive electrode slurry in this embodiment and that in Example 1 is: In step S101, oxalic acid is also added to the first solvent NMP, and LiNi is... 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, PVDF, oxalic acid, and PEOX is set to 95:2.5:1.5:0.75:0.25, which means the mass ratio of oxalic acid to PEOX is 3:1.

[0092] Comparative Example 1: The difference between the preparation method of the high-energy-density lithium-ion battery cathode slurry in this comparative example and that in Example 1 is: PEOX was not added in step S101, and LiNi was... 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, and PVDF is adjusted to 90:5:5.

[0093] Comparative Example 2: The difference between the preparation method of the high-energy-density lithium-ion battery cathode slurry in this comparative example and that in Example 1 is: LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, PVDF, and PEOX is adjusted to 90:5:4.5:0.5, that is, the mass of PEOX is adjusted to 0.5% of the total mass of solute in the electrode slurry.

[0094] Comparative Example 3: The difference between the preparation method of the high-energy-density lithium-ion battery cathode slurry in this comparative example and that in Example 1 is: LiNi 0.8 Co 0.1 Mn 0.1 The mass ratio of O2, SP, PVDF, and PEOX is adjusted to 90:5:4.9:0.1, that is, the mass ratio of PEOX to the total mass of solute in the electrode slurry is adjusted to 0.1%.

[0095] Comparative Example 4: In this comparative example, the preparation method of the high-energy-density lithium-ion battery cathode slurry uses the exact same raw materials as in Example 1, the difference being that all dry powder materials (LiNi) 0.8 Co 0.1 Mn 0.1 O2, SP, PVDF, and PEOX are added to NMP at once; the mixture is first stirred at a low speed of 20 rpm for 30 minutes on a planetary mixer to achieve uniformity, and then continuously dispersed at a high speed of 600 rpm for 240 minutes to obtain the positive electrode slurry.

[0096] The performance of the positive electrode slurry prepared in the above embodiments and comparative examples was tested, and the specific tests are as follows.

[0097] (1) Stability test of positive electrode slurry: The positive electrode slurry was poured into a glass bottle and the initial viscosity of the positive electrode slurry was tested. Then the viscosity of the positive electrode slurry was measured every 12 hours. The stability of the positive electrode slurry was characterized by measuring the viscosity change of the positive electrode slurry after standing for 48 hours. The test results are shown in Table 1.

[0098] Table 1 As shown in Table 1, in Comparative Example 1, without the addition of the nonionic polymeric dispersant PEOX, the initial viscosity of the prepared cathode slurry was relatively high. With prolonged storage time, the viscosity of the cathode slurry increased rapidly, reaching nearly 15000 mPa·s after 12 hours and nearly 35000 mPa·s after 48 hours. This indicates that without the addition of a nonionic polymeric dispersant, the storage stability of the cathode slurry is very poor, making it difficult to meet actual coating requirements. In Comparative Example 2, the amount of nonionic polymeric dispersant PEOX added was too high. Although the initial viscosity of the prepared cathode slurry was relatively low, the viscosity increased rapidly with prolonged storage time, exceeding 10000 mPa·s after 24 hours and nearly 15000 mPa·s after 48 hours. This indicates that with the addition of an excessive amount of nonionic polymeric dispersant, the storage stability of the cathode slurry is poor, making it difficult to meet actual coating requirements. In Comparative Example 3, the amount of nonionic polymeric dispersant PEOX added was too low, resulting in an increase in the initial viscosity of the prepared cathode slurry compared to Example 1. Furthermore, the viscosity increased rapidly with prolonged storage time, exceeding 11000 mPa·s after 24 hours and exceeding 15000 mPa·s after 48 hours. This indicates that the insufficient addition of nonionic polymeric dispersant resulted in inadequate dispersion and poor stability of the cathode slurry, making it difficult to meet actual coating requirements. In Comparative Example 4, although the raw materials for preparing the cathode slurry were the same as in Example 1, the addition of all dry powder materials to the solvent at once made it difficult to maintain uniform and stable dispersion. Although the addition of nonionic polymeric dispersant PEOX resulted in a lower initial viscosity of the cathode slurry, the viscosity gradually increased with prolonged storage time, exceeding 11000 mPa·s after 48 hours. This indicates that when raw materials are added together with solvent, nonionic polymeric dispersants have insufficient dispersion stability for conductive agents and active substances, resulting in poor stability of the positive electrode slurry and making it difficult to meet actual coating requirements.

[0099] The initial viscosity of the positive electrode slurries prepared in Examples 1 to 6 was low, and the viscosity increased slowly with prolonged standing time. After 48 hours, the viscosity remained below 8000 mPa·s, which well meets the stability and coating requirements of slurries in practical applications, i.e., the viscosity of slurries is usually required to remain below 10000 mPa·s after 48 hours. This indicates that, in this application, by optimizing the feeding sequence and dispersion process, and by utilizing the steric hindrance effect of a specific type and appropriate amount of nonionic polymeric dispersant, efficient dispersion of materials can be achieved, effectively reducing and maintaining the viscosity of the electrode slurry, thus giving the electrode slurry excellent rheological properties and storage stability.

[0100] A comparison of the data from Examples 4 to 6 with those from Examples 1 to 3 in Table 1 shows that, after adding oxalic acid to Examples 4 to 6, the cathode slurry still maintained good storage stability despite increasing the proportion of high-nickel ternary materials. This indicates that the added oxalic acid can synergistically enhance the stability of the cathode slurry with the nonionic polymeric dispersant PEOX.

[0101] (2) Particle size distribution test of positive electrode slurry: The particle size and distribution of positive electrode slurry were determined using a laser particle size analyzer. Each sample was tested five times and the average value was taken. The test results are shown in Table 2.

[0102] Table 2 As can be seen from the data in Table 2, in Example 1, the D10, D50, and D90 of the positive electrode slurry are all relatively small, indicating that the positive electrode slurry has good dispersion and uniform particle size distribution. Figure 3 The particle size distribution diagrams are shown for the positive electrode slurries prepared in Example 1 and Comparative Examples 1 to 4. Figure 3It can be seen that the particle size distribution curve of the cathode slurry prepared in Example 1 exhibits a bimodal distribution, indicating that the cathode slurry has a good dispersion effect and uniform particle size distribution. In Comparative Example 2, due to the excessive addition of nonionic polymeric dispersant, the initial viscosity of the prepared cathode slurry is also low. Therefore, the particle size distribution curve of the cathode slurry also exhibits a bimodal distribution. However, the peak value of the particle size distribution curve of the cathode slurry in Example 1 is sharper, and the bulk density is greater. This indicates that the particle size distribution of the cathode slurry prepared in Example 1 is more uniform, and therefore, the cathode slurry has better stability. The cathode slurry prepared in Comparative Example 2 has a low initial viscosity but poor stability. This is consistent with the stability test results of the cathode slurry mentioned above. Although the particle size distribution curve of the cathode slurry prepared in Comparative Example 3 also exhibits a bimodal distribution, the D50 is significantly larger, indicating that the amount of nonionic polymeric dispersant added is too small, resulting in poor dispersion effect. The particle size distribution curve of the positive electrode slurry prepared in Comparative Example 1 shows a multi-peak distribution, indicating that the material in the positive electrode slurry has agglomerated and clumped, resulting in various particle size distributions. The particle size distribution curve of the positive electrode slurry prepared in Comparative Example 4 also shows a multi-peak distribution, indicating that the material in the positive electrode slurry has agglomerated and clumped, resulting in various particle size distributions. Therefore, it can be seen that the positive electrode slurry prepared using the high-energy-density lithium-ion battery electrode slurry preparation method of this application has better dispersion and a more uniform particle size distribution.

[0103] The cathode slurries prepared in the above embodiments and comparative examples are used to prepare high-energy-density lithium-ion batteries. The preparation of high-energy-density lithium-ion batteries includes the following steps: The positive electrode slurries prepared in the above embodiments and comparative examples were left to stand for 24 hours and then coated onto two surfaces of an aluminum foil current collector along the thickness direction. After drying, the slurries were cut into sheets to obtain positive electrode sheets. The loading of the positive electrode slurry after drying was 46 mg / cm³. 2 ; Conductive agent SP and PEOX with a number average molecular weight of 50,000 g / mol were added to deionized water and mixed evenly to obtain a negative electrode pre-dispersion slurry. Silicon-carbon composite material was added to the negative electrode pre-dispersion slurry and mixed evenly to obtain a negative electrode mixed slurry. Adhesive solution (an aqueous solution of CMC and SBR) was added to the negative electrode mixed slurry and mixed evenly to obtain a negative electrode slurry. The mass ratio of silicon-carbon composite material, conductive agent SP, CMC, SBR, and PEOX was 94.25:2:2.5:1:0.25. After the negative electrode slurry was left to stand for 24 hours, it was coated onto two surfaces of a copper foil current collector along the thickness direction. After drying, it was cut into sheets to obtain a negative electrode sheet. The loading of the negative electrode slurry after drying was 16 mg / cm³. 2 ; A PE film with double-sided alumina coating is used as the separator. The above-mentioned positive electrode, negative electrode, and separator are assembled into a cell by stacking. After injecting electrolyte, formation is carried out to obtain a high-energy-density lithium-ion battery. The electrolyte is a solution of 1.1 mol / L lithium hexafluorophosphate dissolved in an organic solvent of diethyl carbonate, ethylene carbonate, and methyl ethyl carbonate in a volume ratio of 2:3:5. By weight percentage, the additives in the electrolyte include 1.5% ethylene sulfate, 5% fluoroethylene carbonate, 1.5% lithium bis(difluorosulfonyl)imide, 2% 1,3-propanesulfonyl lactone, 0.5% 1,3-propenesulfonate lactone, and 0.5% tris(trimethylsilane) phosphate.

[0104] The performance of the fabricated high-energy-density lithium-ion battery was tested using a constant current charge-discharge testing system. Specific tests are as follows: (1) Specific energy test: Charge-discharge tests were conducted using a charge-discharge tester at a current of 0.1C, with a voltage range of 2.5V to 4.2V, to obtain the discharge energy (unit: Wh). Simultaneously, the battery weight (unit: kg) was measured using an electronic balance. Dividing the discharge energy by the battery weight yields the battery's specific energy (unit: Wh / kg). Here, the battery's specific energy can also be referred to as its energy density.

[0105] (2) Capacity retention test after 150 cycles: A charge-discharge test was performed using a charge-discharge tester at a current of 1C for 150 cycles. The discharge capacity C1 of the first cycle and the discharge capacity C150 of the 150th cycle were recorded. The capacity retention rate after 150 cycles was calculated as (C150 / C1) × 100%.

[0106] The test results are shown in Table 3.

[0107] Table 3 As can be seen from the data in Table 3, the high-energy-density lithium-ion batteries prepared using the positive electrode slurries obtained in Examples 1 to 6 all exhibit high specific energy levels, and their capacity retention rates after 150 cycles are significantly higher than those of the comparative examples. This indicates that when the electrode slurry prepared in this application is used in battery fabrication, the conductive agent and active material particles in the electrode slurry can maintain a good and uniform dispersion state during the coating and drying processes. The resulting electrode has a uniform microstructure of active coating, and the conductive agent can form a complete three-dimensional conductive network. This reduces electrode resistance, promotes the capacity utilization of active materials, and ultimately improves the battery's specific energy and cycle life.

[0108] A comparison of the data from Examples 4 to 6 with those from Examples 1 to 3 in Table 3 shows that, after adding oxalic acid in Examples 4 to 6, the oxalic acid can react with the residual alkali on the surface of the high-nickel ternary material, reducing the irreversible side reaction between the residual alkali and the binder PVDF. It can also synergize with the non-ionic polymeric dispersant PEOX, further improving the stability of the positive electrode slurry. Simultaneously, while ensuring the viscosity and stability of the positive electrode slurry, the content of active materials in the positive electrode slurry can be increased (the mass ratio of high-nickel ternary material in the positive electrode slurry increases from 90% to 95%), thereby further improving the specific energy of the battery. As shown in Table 3, using high-nickel ternary material (specific capacity 193.5 mAh / g) as the positive electrode active material and silicon-carbon composite material (specific capacity 600 mAh / g) as the negative electrode active material, combined with the electrode slurry preparation method of this application, the specific energy of a high-energy-density lithium-ion battery can be increased to over 300 Wh / kg.

[0109] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A method for preparing a high-energy-density lithium-ion battery electrode slurry, characterized in that, The method includes: A conductive agent and a nonionic polymeric dispersant are added to a first solvent for a first dispersion treatment to obtain a pre-dispersed slurry; the nonionic polymeric dispersant includes poly(2-ethyl-2-oxazoline); The active substance is added to the pre-dispersed slurry for a second dispersion treatment to obtain a mixed slurry; The adhesive is dissolved in a second solvent to obtain an adhesive solution; The mixed slurry is mixed with the binder solution and stirred to obtain an electrode slurry; wherein the mass of the nonionic polymeric dispersant accounts for 0.15% to 0.40% of the total mass of the solute in the electrode slurry.

2. The method for preparing the high-energy-density lithium-ion battery electrode slurry according to claim 1, characterized in that, The number-average molecular weight of the poly(2-ethyl-2-oxazoline) is 20,000 g / mol to 100,000 g / mol.

3. The method for preparing the high-energy-density lithium-ion battery electrode slurry according to claim 1, characterized in that, The first dispersion treatment is a first high-shear dispersion treatment, wherein the rotation speed of the first high-shear dispersion treatment is 100 rpm to 3000 rpm, and the treatment time is 15 min to 60 min; and / or, The second dispersion treatment is a second high-shear dispersion treatment, wherein the rotation speed of the second high-shear dispersion treatment is 100 rpm to 3000 rpm, and the treatment time is 15 min to 60 min; and / or, The stirring process is vacuum low-speed stirring, with a stirring speed of 20 rpm to 300 rpm and a stirring time of 120 min to 500 min.

4. The method for preparing the high-energy-density lithium-ion battery electrode slurry according to claim 1, characterized in that, The solid content of the electrode paste is 40%~75%; and / or, In the electrode slurry, the mass ratio of the active material, the conductive agent and the binder is (90~96):(2~5):(2~5).

5. The method for preparing the high-energy-density lithium-ion battery electrode slurry according to claim 1, characterized in that, The active material includes a high-nickel ternary material; In the step of preparing the pre-dispersed slurry, oxalic acid is also added to the first solvent.

6. The method for preparing the high-energy-density lithium-ion battery electrode slurry according to claim 5, characterized in that, The mass ratio of oxalic acid to poly(2-ethyl-2-oxazoline) is (1~3):

1.

7. An electrode slurry for high-energy-density lithium-ion batteries, characterized in that, It is prepared by the method for preparing high-energy-density lithium-ion battery electrode slurry according to any one of claims 1 to 6.

8. A method for preparing a high-energy-density lithium-ion battery, characterized in that, The method includes: A positive electrode slurry is coated on at least one side surface of the positive electrode current collector along the thickness direction, and after drying, a positive electrode sheet is obtained. The negative electrode slurry is coated on at least one side surface of the negative electrode current collector along the thickness direction, and after drying, a negative electrode sheet is obtained. Both the positive electrode slurry and the negative electrode slurry are prepared by the method for preparing high-energy-density lithium-ion battery electrode slurry according to any one of claims 1 to 6; A separator is placed between the positive electrode and the negative electrode to assemble an electrode assembly; after packaging the electrode assembly, an electrolyte is injected, and then the assembly undergoes formation and capacity testing to obtain the high-energy-density lithium-ion battery.

9. The method for preparing a high-energy-density lithium-ion battery according to claim 8, characterized in that, The viscosity of the positive electrode slurry is 4000 mPa·s to 8000 mPa·s, and the fineness is ≤20 μm; and / or, The viscosity of the negative electrode slurry is 2700 mPa·s to 4500 mPa·s, and the fineness is ≤40 μm.

10. A high-energy-density lithium-ion battery, characterized in that, It is prepared by the method of high specific energy lithium-ion battery as described in claim 8 or 9.

Images