Lithium ion battery negative electrode material, application of lithium ion battery negative electrode material in all-solid-state battery and preparation method of lithium ion battery negative electrode material

Abstract

The invention discloses a lithium ion battery negative electrode material, application of the lithium ion battery negative electrode material to an all-solid-state battery and a preparation method of the lithium ion battery negative electrode material, and belongs to the technical field of batteries. The negative electrode material comprises 75-85 parts by weight of a carbon black negative electrode active material, 5-10 parts by weight of a binder, 10-20 parts by weight of a solvent and 1-3 parts by weight of a metal additive, and the problems of low energy density, poor cycle performance and high short-circuit rate of an existing negative electrode material are solved by optimizing the type selection and proportion of each component. According to the all-solid-state battery prepared from the negative electrode material, the initial discharge capacity can reach 200mAh / g at most, the short-circuit rate can be reduced to 0% after 100 cycles, and the all-solid-state battery is suitable for the fields of energy storage, electric automobiles, aerospace and the like and has a good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a lithium-ion battery anode material and its application and preparation method in all-solid-state batteries. Background Technology

[0002] In recent years, battery technology, represented by lithium-ion batteries, has been increasingly widely used in energy storage (hydropower plants, thermal power plants, wind power plants, solar power plants), power tools, electric bicycles, electric motorcycles, electric vehicles, aerospace and other fields. With the expansion of application scenarios, the market has placed higher demands on the energy density, cycle performance and safety performance of batteries.

[0003] Solid-state batteries, as a next-generation battery technology, offer higher safety and energy density potential by using solid electrolytes instead of traditional liquid electrolytes, making them a hot research topic in the industry. Among these, electrodeless solid-state batteries have attracted significant attention due to their potential to further improve energy density. However, existing electrodeless solid-state batteries still have significant shortcomings in their anode materials and manufacturing processes. 1. Limitations of negative electrode active materials: Traditional lithium-ion batteries mostly use graphite as the negative electrode, which relies on intercalation reaction to achieve lithium-ion storage. Its capacity has a natural upper limit (the initial discharge capacity is usually only 80mAh / g), which cannot meet the high energy density requirements of all-solid-state batteries. Moreover, graphite is prone to structural collapse after multiple charge-discharge cycles, resulting in rapid capacity decay and a significantly increased risk of short circuit (the short circuit rate can reach 100% after 100 cycles).

[0004] 2. Inappropriate composition ratio and selection: In existing negative electrode materials, the selection and ratio of binders, solvents and additives lack optimization. For example, if the binder has poor compatibility with the active material, it is easy to cause the electrode to pulverize and fall off; if the solvent is residual or reacts with the electrolyte, it will aggravate the deterioration of the electrolyte; if the particle size or type of additive is inappropriate, it cannot effectively improve the battery cycle performance and safety performance, further limiting the improvement of the overall performance of all-solid-state batteries.

[0005] 3. Poor compatibility of the preparation process: In the existing all-solid-state battery preparation process, the uniformity of the negative electrode slurry coating, the control of the encapsulation environment, and the pressing parameters are not matched with the characteristics of the new negative electrode material, which can easily lead to poor contact at the electrode layer interface, increase the risk of short circuit, and make it difficult to give full play to the performance advantages of the negative electrode material.

[0006] Therefore, there is an urgent need to develop a lithium-ion battery anode material with optimized composition and excellent performance, as well as a method for preparing all-solid-state batteries adapted to this material, in order to break through the existing technical bottlenecks and improve the energy density, cycle stability and safety performance of all-solid-state batteries. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing lithium-ion battery anode materials, such as low energy density, poor cycle performance, high short-circuit rate, and poor adaptability to all-solid-state battery fabrication processes. This invention provides a lithium-ion battery anode material, its application in all-solid-state batteries, and an all-solid-state battery fabrication method. By optimizing the selection and ratio of anode material components and combining it with a suitable fabrication process, the invention achieves a significant improvement in the energy density and cycle stability of all-solid-state batteries, while simultaneously reducing the short-circuit rate. The details of this invention are as follows: The first objective of this invention is to provide a lithium-ion battery anode material, the technical point of which is that, by weight percentage, it comprises 75-85 parts by weight of anode active material, 5-10 parts by weight of binder, 10-20 parts by weight of solvent and 1-3 parts by weight of additive, wherein the anode active material is carbon black.

[0008] The second objective of this invention is to provide an application of a lithium-ion battery anode material in all-solid-state batteries.

[0009] The first objective of this invention is to provide a method for preparing an all-solid-state battery, the technical point of which is that it includes the following steps: Step 1, Preparation of negative electrode slurry: The negative electrode active material and binder are added to a solvent and mixed to prepare a slurry; the negative electrode active material is carbon black with an average particle size of 10nm-1000nm; Step 2, metal additive mixing: Additives are added to the slurry, wherein the additives are at least one of silicon, iron, silver, tin, aluminum or copper, and the particle size is 60 nm. Step 3, Coating and Drying: The above slurry is coated onto the current collector foil and dried to form the negative electrode plate; the current collector foil is made of stainless steel, metallic nickel, or nickel plated with copper. Step 4, Battery Assembly: The positive electrode layer, solid electrolyte layer and negative electrode plate are stacked in sequence and encapsulated in a laminated film under vacuum. Then, the film is subjected to hydrostatic pressure treatment at 500MPa for 30 minutes to produce an all-solid-state battery.

[0010] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. This invention uses carbon black as the negative electrode active material, combined with its "direct lithium-ion deposition" energy storage mechanism, breaking through the capacity limit of traditional graphite intercalation reactions. Experimental data shows that the all-solid-state battery prepared with the negative electrode material of this invention can achieve an initial discharge capacity of 100-200 mAh / g (e.g., when 30nm carbon black is combined with silver additives, the initial discharge capacity reaches 200 mAh / g), which is 25%-150% higher than that of traditional graphite negative electrode batteries (80 mAh / g), significantly improving the energy density of all-solid-state batteries.

[0011] 2. This invention effectively improves battery cycle stability by optimizing carbon black particle size (10nm-1000nm), adding metal additives (60nm), and selecting suitable binders: after 100 cycles, the battery short-circuit rate can be controlled at 0%-60% (when 30nm carbon black is combined with silver additives, the short-circuit rate drops to 0%), which is far lower than the 100% short-circuit rate of traditional graphite anode batteries; at the same time, the stable bonding effect of the binder can prevent electrode pulverization, and the barrier effect of carbon black on the electrolyte can inhibit electrolyte degradation, further extending the battery life.

[0012] 3. The components of the anode material of this invention (carbon black, binder, solvent, and additives) are all commonly used materials in the industry, which are easy to obtain and have controllable costs. The preparation process (slurry preparation, coating and drying, vacuum packaging, and hydrostatic treatment) does not require major modifications to existing production equipment, and parameters (such as solvent type and coating method) can be adjusted according to actual needs to adapt to industrial mass production. At the same time, the anode material has good compatibility with the solid electrolyte and positive electrode system of all-solid-state batteries and can be quickly integrated and applied.

[0013] 4. The all-solid-state battery using the negative electrode material and preparation method of this invention has high energy density, high cycle stability and high safety, which can meet the needs of different fields such as energy storage, electric vehicles, and aerospace, and solve the application limitations of existing batteries in high-power and long-life scenarios. Detailed Implementation

[0014] The lithium-ion battery anode material of the present invention comprises the following components by weight percentage: Negative electrode active material (75-85 parts by weight): Carbon black (CB) is selected as the sole negative electrode active material, with an average particle size of 10nm-1000nm. The energy storage mechanism of carbon black differs from that of traditional graphite. After saturation within the carbon black, lithium ions can be directly deposited on the surface of the current collector foil, rather than relying on intercalation reactions. This mechanism can significantly exceed the capacity limit of graphite and improve the energy density of the battery. Furthermore, the particle size range of 10nm-1000nm ensures that the carbon black has a suitable specific surface area and compressibility density, which avoids particle agglomeration affecting ion transport and reduces the risk of short circuits (among which, 30nm particle size carbon black has the best overall performance, enabling the battery to achieve an initial discharge capacity of 195mAh / g and a short circuit rate of only 10% after 100 cycles).

[0015] Binder (5-10 parts by weight): At least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) is selected. This type of binder has good chemical stability and bonding performance, which can effectively encapsulate carbon black particles and firmly bond them to the surface of the current collector foil, preventing electrode pulverization and detachment during charging and discharging. At the same time, it has strong compatibility with the solvents selected later, which can ensure the uniformity of the slurry and does not hinder lithium-ion transport (for example, PVDF is well miscible with polar solvents, and the SBR+CMC composite system is compatible with aqueous solvents, both of which can meet the requirements of slurry preparation).

[0016] Solvent (10-20 parts by weight): A polar or non-polar solvent may be selected. The polar solvent is at least one of N-methylpyrrolidone (NMP) and dimethylformamide (DMF), while the non-polar solvent is at least one of cyclohexane, toluene, and n-hexane. The solvent's function is to dissolve or disperse the binder, bringing the negative electrode slurry to a suitable viscosity (2000-5000 mPa·s) to ensure uniform coating. Furthermore, the selected solvent has a suitable boiling point (NMP approximately 202℃, cyclohexane approximately 80.7℃), leaves no residue after drying, and will not react with the subsequent solid electrolyte, thus preventing electrolyte degradation.

[0017] Additives (1-3 parts by weight): Any one of silicon (Si), iron (Fe), silver (Ag), tin (Sn), or copper (Cu) is selected, with a fixed particle size of 60 nm. These metal additives can work synergistically with carbon black to further optimize battery performance: for example, silver additives can significantly suppress short circuits (the short circuit rate can be reduced to 0% after 100 cycles), while silicon and tin additives can help improve capacity. Moreover, the 60 nm particle size ensures that the additives are uniformly dispersed in the carbon black system without compromising the integrity of the electrode structure.

[0018] 2. Application of lithium-ion battery anode materials in all-solid-state batteries Applying the above-mentioned lithium-ion battery anode materials to the preparation of anodes for all-solid-state batteries, and adapting them to the solid electrolyte system of all-solid-state batteries (such as Argyrodite electrolyte L6P5S1Cl1), can fully leverage the high capacity advantage of carbon black anode active materials. At the same time, through the synergistic effect of additives and binders, the cycle stability and safety performance of all-solid-state batteries can be improved, solving the problems of insufficient energy density and high short-circuit risk of existing all-solid-state batteries. This approach is suitable for various scenarios with high battery performance requirements (such as electric vehicles and aerospace).

[0019] 3. All-solid-state battery fabrication method The method for preparing an all-solid-state battery using the above-mentioned lithium-ion battery anode material includes the following steps: Step 1: Preparation of negative electrode slurry Add 75-85 parts by weight of carbon black (average particle size 10nm-1000nm) and 5-10 parts by weight of binder to 10-20 parts by weight of solvent, and mix by stirring (1000-2000rpm, 2-4h) to form a homogeneous slurry. Select the solvent according to the type of binder: if PVDF or PTFE is used, polar solvents such as NMP or DMF are preferred; if SBR+CMC is used, deionized water is preferred (drying parameters need to be adjusted according to the characteristics of the polar solvent). During the stirring process, ensure that the carbon black and binder are fully dispersed to avoid particle agglomeration.

[0020] Step 2: Mixing metal additives Add 1-3 parts by weight of a metal additive (silicon, iron, silver, tin, or copper, particle size 60 nm) to the slurry prepared in step one, and continue stirring (800-1500 rpm, 1-2 hours) to ensure the additive is evenly dispersed in the slurry. This step requires controlling the stirring intensity to prevent additive particle breakage and ensure the stability of its synergistic effect with carbon black (e.g., when adding silver additive, uniform dispersion is necessary to achieve a short-circuit rate of 0%).

[0021] Step 3: Coating and Drying The slurry prepared in step two is applied to the surface of the current collector foil (made of stainless steel (SUS), metallic nickel (Ni), or nickel-plated copper) using a doctor blade coating or slit coating method, with a coating thickness controlled at 50-100 μm. The coated current collector foil is then placed in a drying oven to dry (80-120℃, 4-6 h) to remove the solvent and form the negative electrode plate. The drying process requires slow heating to avoid rapid solvent evaporation that could cause the electrode layer to shrink and crack, ensuring the integrity of the negative electrode plate structure and good interfacial contact with the subsequent solid electrolyte layer.

[0022] Step 4: Battery Assembly Positive electrode layer preparation: Lithium nickel cobalt manganese oxide (NCM, nickel cobalt manganese ratio 8:1:1) is used as the positive electrode active material, and is mixed with solid electrolyte (Argyrodite electrolyte L6P5S1Cl1) and binder in a weight ratio of 8:1.5:0.5 by dry method, and the positive electrode foil (thickness 100-150μm) is formed by calendering (pressure 10-20MPa).

[0023] Preparation of solid electrolyte layer: Argyrodite electrolyte L6P5S1Cl1, solvent (compatible with negative electrode solvent, such as NMP), binder (PVDF), and conductive additive (carbon black, particle size 10-20nm) are mixed in a weight ratio of 9:0.5:0.3:0.2 to form a slurry, which is then coated on a PET film (thickness 30-50μm) and dried (temperature 100-130℃, time 3-5h) to form a solid electrolyte layer.

[0024] Stacking and encapsulation: Stack the positive electrode layer → solid electrolyte layer → negative electrode plate in the following order (alignment deviation ≤ 0.5 mm). Place the stacked structure in a vacuum environment (vacuum degree ≤ 1 Pa) and encapsulate it in a laminated film. During the encapsulation process, ensure that each part of the positive and negative current collectors protrudes outward from the laminated film (protrusion length 5-10 mm) to serve as the positive and negative terminals, without disrupting the vacuum environment and preventing air and moisture from entering the battery.

[0025] Hydrostatic pressure treatment: The packaged battery is placed in a hydrostatic pressure device and subjected to hydrostatic pressure treatment at 500MPa for 30 minutes to ensure close contact between the positive electrode layer, solid electrolyte layer, and negative electrode plate interface, reduce interface impedance, improve ion transport efficiency, and finally produce an all-solid-state battery.

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. 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.

[0027] Preparation of experimental materials Carbon black: Particle sizes are 30nm (C1), 80nm (C2), 100nm (C3), and 1000nm (C4); Adhesives: PVDF, SBR+CMC (weight ratio 1:1), PTFE; Solvents: NMP (polar), cyclohexane (nonpolar); Metal additives: Ag (60nm), Si (60nm), Sn (60nm); Current collector foil: nickel plated with copper; Positive electrode active material: NCM811; Solid electrolyte: Argyrodite electrolyte L6P5S1Cl1; Other materials: PVDF adhesive, conductive additives (carbon black, 20nm), laminated film.

[0028] Examples 1-4: Anode materials with carbon black of different particle sizes and preparation of all-solid-state batteries Lithium-ion battery anode materials and all-solid-state batteries were prepared using the following parameters, and the effect of carbon black particle size on battery performance was investigated: Negative electrode material composition (parts by weight): 80 kg carbon black, 8 kg PVDF, 12 kg NMP, 2 kg Ag additive (same for Examples 1-4); Carbon black particle size: 30 nm in Example 1, 80 nm in Example 2, 100 nm in Example 3, and 1000 nm in Example 4; Preparation process: Follow steps one through four, with hydrostatic pressure treatment parameters of 500 MPa for 30 min; Performance testing: Under 25℃ conditions, the initial discharge capacity was tested by following the procedure of “0.1C charging to cutoff voltage → constant voltage charging to 0.05C → standing for 10 minutes → 0.1C discharging to termination voltage”; the short circuit rate was tested by cycling 100 times at “0.33C, 4.25V-2.5V”.

[0029] The test results are shown in the table below: ; Examples 5-7: Anode materials with different metal additives and preparation of all-solid-state batteries Based on the 30nm carbon black of Example 1, the types of metal additives were adjusted while other parameters remained unchanged, and the effect of the additives on battery performance was investigated. Example 5: The additive is Si (60nm); Example 6: The additive is Sn (60nm); Example 7: The additive is Ag (60nm).

[0030] The test results are shown in the table below: ; Conclusion: The silver additive has the best effect, which can maximize the initial discharge capacity and reduce the short circuit rate to 0% after 100 cycles.

[0031] Comparative example: Traditional graphite anode materials and all-solid-state battery fabrication Traditional graphite (particle size 1000 nm) was used as the negative electrode active material. Other components (8 parts by weight of PVDF binder, 12 parts by weight of NMP solvent, no additives) and the preparation process were the same as in Example 1. Performance was tested as follows: Initial discharge capacity: 80mAh / g; Short circuit rate after 100 cycles: 100%.

[0032] Conclusion: The lithium-ion battery anode material of the present invention has far superior performance compared to traditional graphite anode materials, and can significantly improve the energy density, cycle stability and safety performance of all-solid-state batteries.

[0033] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A lithium-ion battery anode material, characterized in that, The anode material comprises, by weight percentage, 75-85 parts by weight of negative electrode active material, 5-10 parts by weight of binder, 10-20 parts by weight of solvent and 1-3 parts by weight of additive, wherein the negative electrode active material is carbon black.

2. The lithium-ion battery anode material according to claim 1, characterized in that, The average particle size of the carbon black is 10nm-1000nm.

3. The lithium-ion battery anode material according to claim 1, characterized in that, The additive is any one of silicon, iron, silver, tin, or copper.

4. The lithium-ion battery anode material according to claim 3, characterized in that, The particle size of the additive is 60 nm.

5. The lithium-ion battery anode material according to claim 1, characterized in that, The adhesive is at least one of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl butyral, styrene-butadiene rubber, and sodium carboxymethyl cellulose.

6. The lithium-ion battery anode material according to claim 1, characterized in that, The solvent is either a polar solvent or a non-polar solvent.

7. The lithium-ion battery anode material according to claim 1, characterized in that, The polar solvent is at least one of N-methylpyrrolidone and dimethylformamide.

8. The lithium-ion battery anode material according to claim 1, characterized in that, The nonpolar solvent is at least one of cyclohexane, toluene, and n-hexane.

9. An application of the lithium-ion battery anode material as described in any one of claims 1-8 in an all-solid-state battery.

10. A method for preparing an all-solid-state battery using any of the lithium-ion battery anode materials described in claims 1-8, characterized in that, Includes the following steps: Step 1, Preparation of negative electrode slurry: The negative electrode active material and binder are added to a solvent and mixed to prepare a slurry; the negative electrode active material is carbon black with an average particle size of 10nm-1000nm; Step 2, metal additive mixing: Additives are added to the slurry, wherein the additives are at least one of silicon, iron, silver, tin, aluminum or copper, and the particle size is 60 nm. Step 3, Coating and Drying: The above slurry is coated onto the current collector foil and dried to form the negative electrode plate; the current collector foil is made of stainless steel, metallic nickel, or nickel plated with copper. Step 4, Battery Assembly: The positive electrode layer, solid electrolyte layer and negative electrode plate are stacked in sequence and encapsulated in a laminated film under vacuum. Then, the film is subjected to hydrostatic pressure treatment at 500MPa for 30 minutes to produce an all-solid-state battery.