A lithium-ion battery positive electrode sheet, its preparation method, and a semi-solid-state battery
By introducing aminated cage-type polysilsesquioxane-modified polyacrylic acid and lithium titanium aluminum phosphate into the positive electrode of a lithium-ion battery to form a modified layer, the problems of insufficient safety performance and long preparation time of semi-solid batteries are solved, and the high safety and cycle performance of the battery are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIAOGAN CORNEX NEW ENERGY INNOVATION TECHNOLOGY CO LTD
- Filing Date
- 2024-08-16
- Publication Date
- 2026-07-17
AI Technical Summary
Existing semi-solid-state batteries have insufficient safety performance. High-nickel materials cause the batteries to be prone to thermal runaway under abnormal conditions, and existing preparation methods are not suitable for industrial production.
Introducing aminated cage-type polysilsesquioxane-modified polyacrylic acid into the positive electrode of a lithium-ion battery to form a modified layer, combined with lithium titanium aluminum phosphate, improves the safety and cycle performance of the battery.
It enhances battery safety performance, reduces electrode hardness issues, improves battery thermal and chemical stability, and enhances battery safety and cycle performance.
Smart Images
Figure CN119008846B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a lithium-ion battery positive electrode sheet, its preparation method, and a semi-solid-state battery. Background Technology
[0002] Traditional liquid batteries have an energy density of around 250 Wh / kg, while solid-state batteries have a much higher energy density, currently approaching 400 Wh / kg, and with a strong possibility of breaking the 500 Wh / kg mark, extending the driving range of electric vehicles to over 1000 kilometers and achieving over 500 cycle times. The reason why all-solid-state batteries haven't been commercialized quickly is twofold: firstly, unresolved technical challenges remain, and secondly, their high cost. Semi-solid-state batteries, as a transitional approach, have become the choice of many domestic brands.
[0003] Existing technologies often improve the energy density of semi-solid-state batteries by using high-nickel materials or increasing battery voltage. However, these methods increase the safety risks associated with the batteries. With the use of materials such as NCM523, NCM622, NCM811, and NCM9 / 0.5 / 0.5, the nickel content in the cathode material gradually increases, and the corresponding oxidation and decomposition temperature of the material gradually decreases. At high voltages, the reaction between high-nickel materials and the electrolyte becomes more intense. If a battery assembled from high-nickel materials experiences an abnormality such as a short circuit, overcharge, or over-discharge, the battery temperature rises sharply, leading to thermal runaway, fire, or explosion, causing a safety accident.
[0004] CN 117613404 A discloses an integrated design of positive and negative electrode sheets, a semi-solid battery, and a method for preparing the same. Although this method can improve the rate performance, cycle performance, and safety performance of the semi-solid battery, the preparation process takes a long time and is not suitable for widespread application in industrial production.
[0005] Therefore, how to further improve the safety performance of semi-solid-state batteries has received increasing attention. Summary of the Invention
[0006] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a lithium-ion battery positive electrode sheet in which aminated cage-type polysilsesquioxane-modified polyacrylic acid is introduced, improving the battery's safety performance and maintaining its cycle performance at a high level.
[0007] The lithium-ion battery positive electrode sheet of this invention includes a positive electrode material layer and modified layers on both sides of the positive electrode material layer, wherein the modified layers contain aminated cage-type polysilsesquioxane-modified polyacrylic acid.
[0008] The advantages and technical effects of the lithium-ion battery positive electrode sheet of this invention are as follows: 1. In this invention, the use of aminated cage-type polysilsesquioxane to modify polyacrylic acid can weaken the intermolecular forces of polyacrylic acid, thereby reducing the crystallinity of polyacrylic acid, alleviating the problem of the polyacrylic acid electrode being too hard, and avoiding the occurrence of situations such as electrode breakage and powder shedding caused by the electrode being too hard, which affect battery performance; 2. In this invention, the aminated cage-type polysilsesquioxane has the characteristics of heat resistance, flame retardancy, and high hardness, and at the same time has good thermodynamic stability and chemical stability, and has good compatibility with organic solvents. Introducing polyacrylic acid modified with aminated cage-type polysilsesquioxane into the electrode sheet can improve the safety performance of the battery.
[0009] In some embodiments, the particle size of the aminated cage-type polysilsesquioxane is 500–1000 nm.
[0010] In some embodiments, the modified layer further comprises lithium titanium aluminum phosphate.
[0011] In some embodiments, the mass ratio of lithium titanium aluminum phosphate, aminated cage-type polysilsesquioxane, and polyacrylic acid in the raw materials for preparing the modified layer is 70-90% : 5-15% : 5-15%.
[0012] In some embodiments, the particle size of the lithium titanium aluminum phosphate is 200–500 nm.
[0013] In some embodiments, the thickness of the modified layer is 8–16 μm.
[0014] In some embodiments, the positive electrode material layer comprises lithium nickel cobalt manganese oxide, a binder, and a conductive agent.
[0015] In some embodiments, the mass ratio of lithium nickel cobalt manganese oxide, binder, and conductive agent is 94–98%: 1–3%: 1–3%.
[0016] This invention also provides a method for preparing a lithium-ion battery positive electrode sheet, comprising the following steps:
[0017] (1) Lithium nickel cobalt manganese oxide, binder and conductive agent are added to an organic solvent to form a slurry. The slurry is coated on both sides of the current collector aluminum foil and dried to obtain the positive electrode material layer.
[0018] (2) Lithium aluminum titanium phosphate, aminated cage-type polysilsesquioxane and polyacrylic acid are added to an organic solvent to form a slurry. The resulting slurry is coated on both sides of the positive electrode material layer obtained in step (1) and then dried.
[0019] The present invention also provides a semi-solid battery containing the above-described lithium-ion battery positive electrode sheet or the lithium-ion battery positive electrode sheet prepared by the above-described preparation method. Attached Figure Description
[0020] Figure 1 This is a SEM image of the lithium-ion battery positive electrode sheet prepared in Example 1;
[0021] Figure 2 The graph shows the cycle performance of the semi-solid lithium-ion batteries prepared in Example 1 and Comparative Example 1 at room temperature. Detailed Implementation
[0022] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0023] The lithium-ion battery positive electrode sheet of this invention includes a positive electrode material layer and modified layers on both sides of the positive electrode material layer, wherein the modified layers contain polyacrylic acid (PAA) modified with aminated cage-type polysilsesquioxane (POSS-NH2).
[0024] The lithium-ion battery positive electrode of this invention uses POSS-NH2 modified PAA, which weakens the intermolecular forces of polyacrylic acid, thereby reducing the crystallinity of polyacrylic acid, alleviating the problem of the polyacrylic acid electrode being too hard, and avoiding the occurrence of battery performance issues such as electrode breakage and powder shedding caused by the electrode being too hard. The aminated cage-like polysilsesquioxane has the characteristics of heat resistance, flame retardancy, and high hardness, and also has good thermodynamic and chemical stability, as well as good compatibility with organic solvents. Introducing polyacrylic acid modified with aminated cage-like polysilsesquioxane into the electrode can improve the safety performance of the battery.
[0025] In some embodiments, preferably, the particle size of POSS-NH2 is 500 to 1000 nm, such as 500 nm, 600 nm, 700 nm, 800 nm, 900 nm or 1000 nm.
[0026] In this embodiment of the invention, the particle size of POSS-NH2 is preferred. Optimizing the particle size within this range not only ensures uniform dispersion in the matrix, improving battery safety, but also ensures that ions have suitable diffusion paths, thereby enabling the battery to have higher rate capability and cycle performance. If the particle size is too large, the ion diffusion path increases, affecting the battery's rate capability and cycle performance. If the particle size is too small, it is not easy to disperse uniformly in the matrix, which may lead to localized agglomeration and become a safety hazard for the battery.
[0027] In some embodiments, preferably, the modified layer further comprises lithium aluminum titanium phosphate (LATP) and a conductive agent. More preferably, the mass ratio of lithium aluminum titanium phosphate, aminated cage-type polysilsesquioxane, and polyacrylic acid in the raw materials for preparing the modified layer is 70–90% : 5–15% : 5–15%.
[0028] In this embodiment of the invention, LATP is added to the modified layer. LATP, as an oxide solid electrolyte that conducts ions but does not conduct electrons, further increases the electrode contact resistance under short circuit or other thermal abuse conditions in lithium-ion batteries, reduces the risk of thermal runaway, and improves battery safety. The POSS-NH2 modified PAA is obtained by amidation reaction of the amino group in POSS-NH2 and the carboxyl group in PAA. The ratio of POSS-NH2 to PAA in the raw materials is further limited to ensure that the reaction proceeds smoothly and obtains an appropriate amount of POSS-NH2 modified PAA.
[0029] In some embodiments, preferably, the particle size of the LATP is 200-500 nm, such as 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm.
[0030] In this embodiment of the invention, the particle size of LATP is preferred. Optimizing the particle size of LATP within this range not only ensures its uniform dispersion in the matrix, improving battery safety performance, but also ensures that ions have suitable diffusion paths, thereby enabling the battery to have higher rate capability and cycle performance. If the particle size is too large, the ion diffusion path increases, which is not conducive to improving the battery's rate capability and cycle performance. If the particle size is too small, it is not easy to uniformly disperse in the matrix, which is not conducive to improving battery safety performance.
[0031] In some embodiments, preferably, the thickness of the modified layer is 8 to 16 μm, such as 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm or 16 μm.
[0032] In some embodiments, preferably, the positive electrode material layer comprises lithium nickel cobalt manganese oxide, a binder, and a conductive agent. More preferably, the mass ratio of lithium nickel cobalt manganese oxide, binder, and conductive agent in the positive electrode material layer is 94–98%:1–3%:1–3%. Even more preferably, the binder comprises at least one of polyvinylidene fluoride, polyvinyl alcohol, or polytetrafluoroethylene, and the conductive agent comprises at least one of conductive carbon black, carbon nanotubes, or acetylene black.
[0033] This invention also provides a method for preparing a lithium-ion battery positive electrode sheet, comprising the following steps:
[0034] (1) Lithium nickel cobalt manganese oxide, binder and conductive agent are added to an organic solvent to form a slurry. The slurry is coated on both sides of the current collector aluminum foil and dried to obtain the positive electrode material layer.
[0035] (2) Add LATP, POSS-NH2 and PAA to an organic solvent to form a slurry, coat the resulting slurry on both sides of the positive electrode material layer obtained in step (1), and dry it.
[0036] In some embodiments, preferably, in step (1) and / or step (2), the organic solvent comprises N-methylpyrrolidone (NMP); and the solid content of the slurry is 20–40 wt%.
[0037] In some embodiments, preferably, in step (1) and / or step (2), the drying temperature is 90–110°C.
[0038] The present invention also provides a semi-solid battery containing the above-described lithium-ion battery positive electrode sheet or the lithium-ion battery positive electrode sheet prepared by the above-described preparation method.
[0039] The technical solution of this application will be described in detail below with reference to specific embodiments and accompanying drawings.
[0040] Example 1
[0041] (1) Preparation of positive electrode material layer: 97% lithium nickel cobalt manganese oxide, 1.5% polyvinylidene fluoride (PVDF) as positive electrode binder and 1.5% conductive carbon black as positive electrode conductive agent are weighed according to the mass ratio. First, PVDF is added to N-methylpyrrolidone solvent to prepare a slurry. Then, conductive carbon black is added to the above slurry and stirred until uniform. Then, lithium nickel cobalt manganese oxide is added to the above slurry and stirred until uniform. Finally, the slurry is coated on the current collector and dried to obtain the positive electrode material layer.
[0042] (2) Lithium-ion battery positive electrode sheet containing aminated cage-type polysilsesquioxane modified polyacrylic acid: 10% POSS-NH2, 80% LATP and 10% binder PAA are weighed by mass. First, PAA is added to N-methylpyrrolidone solvent to prepare a slurry. Then, POSS-NH2 and LATP are added to the above slurry and stirred until uniform to obtain a slurry. Finally, the slurry is coated on the positive electrode material layer obtained in step (1), dried, and then rolled and slit to obtain small positive electrode sheets. The thickness of the double-sided coating is 12 μm. Among them, the particle size of POSS-NH2 material is 800 nm and the particle size of LATP powder is 350 nm.
[0043] (3) Preparation of negative electrode sheet: Weigh 76% graphite negative electrode material, 19% silicon suboxide negative electrode material, 2.5% negative electrode binder polyacrylic acid and 2.5% negative electrode conductive agent conductive carbon black according to the mass ratio. First, add polyacrylic acid to deionized water to make a glue solution. Then add conductive carbon black, graphite and silicon oxide to the above glue solution and stir until uniform. Finally, coat the slurry on the current collector and dry it to prepare the negative electrode sheet. After rolling and cutting, the negative electrode sheet is obtained.
[0044] (4) Preparation of the battery cell: The positive and negative electrode small pieces are vacuum baked, stacked to form a battery cell and encapsulated in an aluminum-plastic film.
[0045] (5) Battery preparation: After baking, the battery cell is injected with liquid, formed, aged and tested for capacity to obtain a semi-solid battery.
[0046] The lithium-ion battery cathode sheet prepared in this embodiment was characterized by SEM, and its cross-sectional SEM image is shown below. Figure 1 As shown: From Figure 1 As can be seen, the modified layer is uniformly coated on the surface of the cathode material layer (both sides of the cathode material layer are coated with the modified layer, but only one side is shown in the figure).
[0047] Example 2
[0048] The preparation method of this embodiment is the same as that of Example 1, except that in step (2), 5% of POSS-NH2, 90% of LATP and 5% of binder PAA are weighed by mass, and the thickness of the double-sided coating is 8 μm.
[0049] Example 3
[0050] The preparation method of this embodiment is the same as that of Example 1, except that in step (2), 15% of POSS-NH2, 70% of LATP and 15% of PAA are weighed by mass, and the thickness of the double-sided coating is 16 μm.
[0051] Example 4
[0052] The preparation method of this embodiment is the same as that of Example 1, except that in step (2), the particle size of POSS-NH2 material is 500 nm, the particle size of LATP powder is 200 nm, and the thickness of the double-sided coating is 8 μm.
[0053] Example 5
[0054] The preparation method of this embodiment is the same as that of Example 1, except that in step (2), the particle size of POSS-NH2 material is 1000 nm, the particle size of LATP powder is 500 nm, and the thickness of the double-sided coating is 16 μm.
[0055] Comparative Example 1
[0056] The preparation method of this comparative example is the same as that of Example 1, except that step (2) is cancelled. After step (1) is completed, the positive electrode small piece is obtained directly by rolling and cutting.
[0057] Comparative Example 2
[0058] The preparation method of this comparative example is the same as that of Example 1, except that in step (2), POSS is used instead of POSS-NH2.
[0059] The performance of the semi-solid-state batteries prepared in Examples 1-5 and Comparative Examples 1-2 was tested:
[0060] (1) Capacitive internal resistance: An AC internal resistance tester was used;
[0061] (2) Capacity retention rate: The battery was charged to 4.2V at 0.5C constant current and constant voltage at room temperature, and discharged to 2.5V at 1C constant current for 800 cycles. The discharge capacity retention rate was calculated. The capacity retention rate curves of the semi-solid-state batteries prepared in Example 1 and Comparative Example 1 are shown below. Figure 2 As shown;
[0062] (3) Low-temperature discharge capacity retention rate: The battery was charged to 4.2V at 0.5C constant current and constant voltage at room temperature, placed at -30℃ for 4h, and discharged to 2.0V at 0.5C constant current. The discharge capacity retention rate was calculated.
[0063] (4) Needle penetration: in accordance with GB31485-2015 Safety requirements and test methods for power batteries for electric vehicles.
[0064] Table 1
[0065]
[0066] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0067] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. A positive electrode sheet for a lithium-ion battery, characterized in that, It includes a positive electrode material layer and modified layers on both sides of the positive electrode material layer, wherein the modified layers contain aminated cage-type polysilsesquioxane modified polyacrylic acid and lithium titanium aluminum phosphate; The mass ratio of lithium titanium aluminum phosphate, aminated cage-type polysilsesquioxane, and polyacrylic acid in the raw materials for preparing the modified layer is 70-80% : 10-15% : 10-15%; The aminated cage-type polysilsesquioxane has a particle size of 500~1000nm, and the lithium titanium aluminum phosphate has a particle size of 200~500nm.
2. The lithium-ion battery positive electrode sheet according to claim 1, characterized in that, The thickness of the modified layer is 8~16μm.
3. The lithium-ion battery positive electrode sheet according to claim 1, characterized in that, The positive electrode material layer contains lithium nickel cobalt manganese oxide, a binder, and a conductive agent.
4. The lithium-ion battery positive electrode sheet according to claim 3, characterized in that, The mass ratio of lithium nickel cobalt manganese oxide, binder and conductive agent is 94~98%:1~3%:1~3%.
5. The method for preparing a lithium-ion battery positive electrode sheet according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Lithium nickel cobalt manganese oxide, binder and conductive agent are added to an organic solvent to form a slurry. The resulting slurry is coated on both sides of the current collector aluminum foil and dried to obtain the positive electrode material layer. (2) Lithium aluminum titanium phosphate, aminated cage-type polysilsesquioxane and polyacrylic acid are added to an organic solvent to form a slurry. The slurry is coated on both sides of the positive electrode material layer obtained in step (1) and then dried.
6. A semi-solid-state battery, characterized in that, The positive electrode of a lithium-ion battery contains the positive electrode sheet of any one of claims 1 to 4 or the positive electrode sheet of a lithium-ion battery prepared by the preparation method of claim 5.