All-solid-state positive electrode sheet and preparation method and application thereof
By employing discontinuous coating of interface-stabilized ionic conductors and nano-pulse jetting technology in the positive electrode of all-solid-state batteries, the interface problem when sulfide electrolytes come into contact with positive electrode active particles has been solved, achieving efficient and low-cost battery fabrication and improved stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGSHU INSTITUTE OF TECHNOLOGY
- Filing Date
- 2026-03-27
- Publication Date
- 2026-06-09
AI Technical Summary
When preparing all-solid-state batteries, a space charge layer is generated when the sulfide electrolyte comes into contact with the positive electrode active particles, which hinders lithium-ion migration, leading to capacity decay and decreased interface stability. Existing processes are complex and costly, making it difficult to achieve large-scale production and industrialization.
A wet process is used to discontinuously attach an interfacially stable ionic conductor between a sulfide electrolyte and a positive electrode active material. A discontinuous coating layer is formed by nano-pulse jetting technology, and a conductive agent is mixed between the electrolyte particles to form a structure in which the active material and the conductive agent are in contact, thus creating both ionic and electronic pathways.
This technology enables the efficient preparation of all-solid-state battery cathode sheets, reduces costs, improves electrochemical and interfacial stability, simplifies the process, and is suitable for large-scale production.
Smart Images
Figure CN122177743A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of solid-state battery technology, particularly to the field of all-solid-state battery technology, and further to a positive electrode, a solid-state battery, and an electrical device. Background Technology
[0002] Solid-state batteries use non-flammable or high-ignition-point solid electrolytes to replace traditional organic liquid electrolytes, significantly improving the safety of the battery system and simultaneously increasing the system's energy density. Among various solid electrolytes, sulfide solid electrolytes, with ionic conductivity comparable to liquid electrolytes, have become the mainstream in application and research, mainly including Thio-LISICON and Li... 10 GeP2S 12 Li 10 SnP2S 12 、For Li 7-X PS 6-X M X (M includes any one or at least two of Cl, Br, F, or I, 0.1 ≤ x ≤ 5.9), Li₂S-P₂S₅, Li 10 SiP2S 12 Li₂S-Si₂S₂, Li₂S-B₂S₃, etc., have room temperature ionic conductivity up to 10. -3 ~10 -2 With a S / cm ratio approaching or even exceeding that of organic electrolytes, it also features high thermal stability and good safety, making it a standout in high-power and high-low temperature solid-state battery applications.
[0003] However, when using sulfide electrolytes to prepare all-solid-state batteries, a space charge layer is generated when it comes into contact with the positive electrode active particles. The presence of this space charge layer hinders the further migration of lithium ions, leading to capacity decay and decreased interface stability. On the other hand, various insulating products are also generated at the contact interface, causing electrode degradation and increased impedance. Although researchers have used wet processes to coat the positive electrode surface with ion-conducting and electron-conducting insulators to reduce this effect, continuous coating layers still cause an increase in interface impedance. Moreover, the continuous or discontinuous coating process of positive electrode active material particles is complex and costly (usually requiring secondary sintering). Although dry electrode sheets have better performance, continuous preparation remains a problem, which is not conducive to large-scale and industrial development. Therefore, researchers have been exploring new processes to balance the preparation efficiency, performance, and cost of sulfide all-solid-state battery positive electrodes. Summary of the Invention
[0004] This invention provides a wet-process method for preparing sulfide cathode sheets. This method combines material properties with the preparation process, achieving a relatively balanced solution to the contradictions between electrode preparation efficiency, cost, and performance. Compared with the traditional process of first coating the cathode material and then preparing the slurry, this method is simpler, achieves comparable or better results, and has higher material compatibility. The electrode preparation process of this invention effectively possesses advantages over traditional single-sided coating, achieving a near-bidirectional coating effect, which is beneficial for reducing the cost of all-solid-state battery cathode sheet preparation.
[0005] The first aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive active material layer located on at least one side of the positive current collector, the positive active material layer comprising a positive active material, a positive solid electrolyte, an interface-stabilized ionic conductor, a conductive agent and a binder; The positive electrode solid electrolyte is a sulfide electrolyte, and the interfacial stable ionic conductor is discontinuously attached between the sulfide electrolyte and the positive electrode active material.
[0006] Preferably, the positive electrode active material is LiNi. x Co y M z O2, wherein M includes at least one of Mn, Al, Zr, Ti, V, Mg, Fe or Mo, 0≤x<1, 0≤y<1, 0≤z<1, and x+y+z=1.
[0007] Preferably, the interface-stabilized ionic conductor material includes Li 1+x Al x Ti 2-x At least one of the following: (PO4)3, LLZO, LLTO, LAGP, LiPON, Li2TiO3, LiNbO3, Li3BO3, Li2ZrO3, LiCoO3, LiPO3, Al(PO3)3, La(PO3)3, and NaPO3; wherein Li 1+x Al x Ti 2-x In (PO4)3, 0 < x < 1; the particle size range of the interface-stabilized ionic conductor is 10–200 nm.
[0008] Preferably, the electrode sulfide electrolyte is Thio-LISICON or Li 10 GeP2S 12 Li 10 SnP2S 12 Li 7- x PS 6-x M x Li₂S-P₂S₅, Li 10 SiP2S12 At least one of Li₂S-Si₂S₂ and Li₂S-B₂S₃; wherein Li 7-x PS 6-x M x In this context, M includes at least one of Cl, Br, F, and I, and 0.1 ≤ x ≤ 5.9.
[0009] Preferably, the mass percentages of the positive electrode active material, positive electrode solid electrolyte, conductive agent, binder, and interface stable ionic conductor material are 60%~90%: 6.5%~39.7%: 0.1%~2%: 0.1%~2%: 0.1%~0.5%.
[0010] A second aspect of the present invention provides a method for preparing the above-mentioned positive electrode sheet, the method comprising the following steps: S1. Disperse the positive electrode active material using a solvent to form a homogenate; S2. The atomized interface-stabilized ionic conductor premixed liquid is pulse-sprayed into the stirring positive electrode active material slurry to obtain the first slurry; S3. Add the sulfide electrolyte premix to the first slurry and continue mixing and homogenizing to obtain the second slurry; S4. After adding the conductive agent premix to the second slurry, homogenize the mixture to obtain the third slurry; S5. A third slurry is coated on at least one surface of the positive current collector, and the positive electrode sheet is obtained after drying and rolling.
[0011] Preferably, at least one of the interface-stabilized ionic conductor premix, sulfide electrolyte premix, and conductive agent premix contains a binder, wherein the binder has a mass percentage of 0.1-10% in the premix and a solid content of 2-80%.
[0012] Preferably, the working viscosity of the interface-stabilized ionic conductor premix is 10~50 mPa·s; the pulse injection pressure is 2~10 MPa; the pulse injection time is 0.1~1 s; and the interval time is 1~30 s.
[0013] Preferably, the solvent includes at least one selected from dichloromethane, tetrahydrofuran, n-hexane, n-heptane, toluene, 2,4-dimethyl-3-pentanone, monochlorobenzene, xylene, toluene, isobutyl isobutyrate, anisole, cyclohexanone, 1,3,5-trimethylbenzene, n-decane, dodecane, and methylformamide.
[0014] A third aspect of the present invention provides a solid-state battery, the solid-state battery comprising a negative electrode, a positive electrode, and an electrolyte sheet, wherein the positive electrode is the positive electrode described above, or a positive electrode prepared by the above preparation method.
[0015] The technical solution of the present invention has at least the following beneficial effects: (1) The present invention forms a nano-discontinuous interface-stabilized ionic conductor coating layer on the positive electrode particles, forms a large electrolyte particle coating on the coating layer, and then mixes a conductive agent into the gap between the electrolyte particles, thereby forming a structure in which the active material first contacts the conductive agent and then contacts the electrolyte particles, forming an ideal form with both ionic and electronic pathways outside the coated interface-stabilized ionic conductor.
[0016] (2) The interface stable ionic conductor not only forms a discontinuous coating morphology of the positive electrode active particles, but also forms a local coating of the sulfide electrolyte in the electrode structure, avoiding excessive contact between the sulfide electrolyte and the positive electrode active material, thus preventing decomposition.
[0017] (3) The method for preparing the all-solid-state battery positive electrode provided by the present invention does not require the use of ion conductors to coat the positive electrode particles in advance. The interface-stable ion conductors are attached between the sulfide electrolyte and the positive electrode particles by high-pressure nano-pulse spraying and are filled in the slurry. As the coating layer dries and stabilizes, it protects the sulfide electrolyte itself and avoids the decomposition of sulfide by high voltage during positive electrode charging. Compared with the preparation of positive electrode sheets by coating the positive electrode particles in advance, it has better convenience, electrochemical stability and low cost.
[0018] (4) The core technology of the preparation method lies in the pulse jet mixing and homogenization process of the interface-stabilized ionic conductor. The atomizing pulse jet equipment uses an electronic control system to precisely control the nano-airflow formed by the mixing of nanoparticles and argon gas, which directly sprays the nano-ionic conductor into the homogenizing tank through several micron nozzles. Combined with the electronic control unit, the spray volume and pulse band are adjusted in real time. The interface-stabilized ionic conductor premix is pulse-jet dispersed into the positive electrode active material being dispersed in the solvent, and gradually adheres to the surface of the positive electrode particles or fills the gaps between the particle surfaces as the mixing progresses, forming a metastable interface-stabilized ionic conductor coating layer. In the following step, the sulfide electrolyte premix sandwiches the interface ionic conductor between the larger electrolyte particles and the positive electrode particles, at which point this discontinuous coating layer becomes more stable. As homogenization continues, some of the interfacial ionic conductors remaining in the slurry adhere to the sulfide electrolyte particles, while others remain permanently at the interfaces of the slurry particles. After the slurry is coated, these conductors act as stable interfacial ionic conductors between the active layer and the current collector, preventing the current collector side from oxidizing and decomposing the sulfide particles in the active layer under high SOC conditions.
[0019] (5) The interface-stabilized ion conductor coating layer of the present invention needs to have bidirectional stability characteristics with the positive electrode particles and the sulfide electrolyte, meet the high voltage electrochemical stability, reduce the direct contact between the positive electrode particles and the sulfide electrolyte particles, and serve as a bridge for lithium ion transfer. Under the dual effects of the above material selection and process, the wet-processed sulfide positive electrode sheet has better convenience and electrochemical stability than the electrode sheet prepared by coating the positive electrode particles separately in advance. Attached Figure Description
[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0021] Figure 1 It is a particle agglomeration of the material composite structure in the active layer of the present invention.
[0022] Figure 2 This is a schematic diagram of the structure of the positive electrode active layer in an embodiment of the present invention.
[0023] Figure 3 This is a flowchart of the preparation method of the all-solid-state battery positive electrode sheet in the embodiments of the present invention.
[0024] Figure 4 This is a comparison chart of the cyclic stability of Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation
[0025] In the description of this application, the list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.
[0026] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges, or individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Unless otherwise stated, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.
[0027] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0028] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.
[0029] like Figures 1-2 As shown, a first aspect of the present invention provides a positive electrode sheet, the positive electrode sheet comprising a positive current collector and a positive active material layer located on at least one side of the positive current collector, the positive active material layer comprising a positive active material, a positive solid electrolyte, an interface-stabilized ionic conductor, a conductive agent and a binder; The positive electrode solid electrolyte is a sulfide electrolyte, and the interfacial stable ionic conductor is discontinuously attached between the sulfide electrolyte and the positive electrode active material.
[0030] In one embodiment, the positive electrode active material is LiNi. x Co y M z O2, wherein M includes at least one of Mn, Al, Zr, Ti, V, Mg, Fe or Mo; 0≤x<1, for example: x can be 0, 0.1, 0.3, 0.5, 0.7, 0.8 or 0.9, etc.; 0≤y<1, for example: y can be 0, 0.1, 0.3, 0.5, 0.7, 0.8 or 0.9, etc.; 0≤z<1, for example: z can be 0, 0.1, 0.3, 0.5, 0.7, 0.8 or 0.9, etc.; and x+y+z=1.
[0031] In one embodiment, the interface-stabilized ionic conductor material includes Li 1+x Al x Ti 2-xAt least one of (PO4)3, LLZO, LLTO, LAGP, LiPON, Li2TiO3, LiNbO3, Li3BO3, Li2ZrO3, LiCoO3, LiPO3, Al(PO3)3, La(PO3)3, and NaPO3.
[0032] In one embodiment, Li 1+x Al x Ti 2-x (PO4)3 represents the chemical formula of lithium aluminum titanium phosphate electrolyte (LATP), where 0 < x < 1, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, etc.
[0033] In one embodiment, the chemical formula of lithium lanthanum zirconium oxide (LLZO) is Li7La3Zr2O. 12 .
[0034] In one embodiment, the chemical formula of lithium lanthanum titanium oxide (LLTO) is Li7La3Ti2O. 12 .
[0035] In one embodiment, lithium aluminum germanium phosphate (LAGP) has the chemical formula Li. (1+y) Al y Ge (2-y) (PO4)3, where 0≤y≤0.5, for example, y can be 0.1, 0.2, 0.3, 0.4 or 0.5, etc.
[0036] In one embodiment, the particle size range of the interface-stabilized ionic conductor is 10–200 nm, such as 10 nm, 30 nm, 50 nm, 80 nm, 100 nm, 130 nm, 150 nm, or 200 nm.
[0037] In one embodiment, the electrode sulfide electrolyte is Thio-LISICON or Li 10 GeP2S 12 Li 10 SnP2S 12 Li 7-x PS 6-x M x Li₂S-P₂S₅, Li 10 SiP2S 12 At least one of Li₂S-Si₂S₂ and Li₂S-B₂S₃; wherein Li 7-x PS 6-x M xIn the formula, M includes at least one of Cl, Br, F, and I, and 0.1 ≤ x ≤ 5.9. For example, x can be 0.2, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, etc.
[0038] In one embodiment, the mass percentages of the positive electrode active material, positive electrode solid electrolyte, conductive agent, binder, and interface-stabilized ionic conductor material are 60%~90%: 6.5%~39.7%: 0.1%~2%: 0.1%~2%: 0.1%~0.5%.
[0039] In one embodiment, the conductive agent includes at least one of zero-dimensional conductive agents, one-dimensional conductive agents, and two-dimensional conductive agents.
[0040] In one embodiment, the zero-dimensional conductive agent includes conductive carbon black (SP) and / or acetylene black (AB); the one-dimensional conductive agent includes carbon nanotubes (CNT) and / or vapor-grown carbon fibers (VGCF); and the two-dimensional conductive agent includes graphene.
[0041] In one embodiment, the adhesive includes at least one of PVDF5130, PVDF75130, PVDF21216, PVDF6020, PVDF-HVS900, PVDF-HFP, PVDF-LBG, PIB, NBR, HNBR, SBR, SBS, SEBS, PTEF, and PEO.
[0042] In one embodiment, the molecular weight of the adhesive is 10 to 5 million, for example: 200,000, 300,000, 500,000, 1 million, 2 million, 3 million or 5 million, etc.
[0043] In one embodiment, the areal capacity of the positive electrode is 3 mAh / cm². 2 ~10mAh / cm 2 For example, the surface capacity could be 3mAh / cm². 2 4mAh / cm 2 5mAh / cm 2 6mAh / cm 2 7mAh / cm 2 8mAh / cm 2 9mAh / cm 2 10mAh / cm 2 wait.
[0044] like Figure 3 As shown, a second aspect of the present invention provides a method for preparing the above-mentioned positive electrode sheet, the method comprising the following steps: S1. Disperse the positive electrode active material using a solvent to form a homogenate; S2. The atomized interface-stabilized ionic conductor premixed liquid is pulse-sprayed into the stirring positive electrode active material slurry to obtain the first slurry; S3. Add the sulfide electrolyte premix to the first slurry and continue mixing and homogenizing to obtain the second slurry; S4. After adding the conductive agent premix to the second slurry, homogenize the mixture to obtain the third slurry; S5. A third slurry is coated on at least one surface of the positive current collector, and the positive electrode sheet is obtained after drying and rolling.
[0045] In one embodiment, at least one of the interface-stabilized ionic conductor premix, sulfide electrolyte premix, and conductive agent premix contains a binder, wherein the binder has a mass percentage of 0.1% to 10% in the premix, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc.; and a solid content of 2% to 80%, for example, 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, etc.
[0046] In one embodiment, the binder content in the interface-stabilized ionic conductor premix is 0.1% to 10%, and the solid content is 20% to 80%.
[0047] In one embodiment, the sulfide electrolyte premix contains 0.1% to 5% binder and 30% to 80% solids.
[0048] In one embodiment, the conductive agent premix liquid contains 0.1% to 5% binder and 2% to 10% solids.
[0049] In one embodiment, the third slurry has a solid content of 45% to 80%.
[0050] In one embodiment, the working viscosity of the interface-stabilized ionic conductor premix is 10~50 mPa·s, for example, it can be 15 mPa·s, 20 mPa·s, 25 mPa·s, 30 mPa·s, 35 mPa·s, 40 mPa·s, 45 mPa·s, etc.
[0051] In one embodiment, the pulse jet pressure is 2-10 MPa; the pulse jet time is 0.1-1 s; and the interval time is 1-30 s. These are the time parameters for one cycle of jetting. In the pulse jetting process, the above cycle needs to be repeated until the content of the interfacial stable ionic conductor in the formulation is reached, at which point the pulse jetting process is stopped. For example, the total time for step S2 is 10-240 min, such as 20 min, 40 min, 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, etc.
[0052] In one embodiment, the solvent includes at least one of dichloromethane, tetrahydrofuran, n-hexane, n-heptane, toluene, 2,4-dimethyl-3-pentanone, monochlorobenzene, xylene, toluene, isobutyl isobutyrate, anisole, cyclohexanone, 1,3,5-trimethylbenzene, n-decane, dodecane, and methylformamide.
[0053] In one embodiment, the single inner diameter of the nanoscale interface-stabilized ion conductor premixed liquid spray head is 10~30μm, and the atomizing nozzle is composed of several single nozzles, which are adjusted according to experimental requirements, generally ranging from 10 to 10000.
[0054] In one embodiment, the dispersion or homogenization time in steps S1, S3, and S4 can be independently selected as 15 to 120 minutes, such as 20 minutes, 40 minutes, 60 minutes, 80 minutes, 100 minutes, etc., and the dispersion or homogenization method includes stirring, ball milling, etc.
[0055] In one embodiment, the drying temperature in step S5 is 60~120℃, and the drying time is 5~24h.
[0056] A third aspect of the present invention provides a solid-state battery, the solid-state battery comprising a negative electrode, a positive electrode, and an electrolyte sheet, wherein the positive electrode is the positive electrode described above, or a positive electrode prepared by the above preparation method.
[0057] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.
[0058] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.
[0059] Example 1 A method for preparing a positive electrode sheet for an all-solid-state battery, comprising the following steps: The composition of the positive electrode active material layer was designed according to the following ratio: positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PVDF-HFP: nano-ionic conductor LATP, with a ratio of 76%: 20.9%: 1%: 2%: 0.1%. (1) Disperse the positive electrode active material NCM811 by ball milling with xylene for 20 min according to the proportion; (2) Pulse spray LATP premix in the dispersion. The average particle size of LATP is 100 nm. The binder in the premix is PVDF-HFP. The glue content is 2%. The viscosity of the premix is 20 mPa·s. The pulse spraying conditions are pressure 3 MPa, pulse spraying time 0.5 s, and interval time 5 s. Pulse spraying is stopped after the designed LATP content in the formula is reached. (3) After the pulse jetting is finished, continue ball milling for 15 minutes, add sulfide electrolyte premix, the premix has a gum content of 1% and a solid content of 50%, and continue mixing for 20 minutes after the premix is added; (4) After completing the steps in (3) above, add the conductive agent premix to the mixture, wherein the binder content is 0.5% and the solid content is 5%, and add all the remaining materials (binder) not added in the other formula, and continue mixing for 60 minutes to complete the slurry preparation; (5) The above-completed slurry is coated onto carbon-coated aluminum foil, vacuum dried at 100°C for 8 hours, and then rolled for later use. The electrode is designed with an areal capacity of 5 mAh / cm². 2 .
[0060] Solid-state battery testing: The electrode sheet prepared in step (5) was punched to a diameter of 10 mm, and 100 mg of Li was taken. 5.5 PS 4.5 Cl 1.5The electrolyte sheet was prepared by placing the sample into a 10mm aperture mold battery and holding it at 300MPa for 5 minutes. This sample served as the working electrode. A composite negative electrode, consisting of a 10mm diameter, 100μm thick indium foil and a 50μm thick lithium-copper composite strip, was then used as the counter electrode, with the indium foil facing the electrolyte layer. The mold half-cell was then assembled. Cyclic performance testing was conducted on the prepared half-cell at 100MPa and 30℃, using a 0.33C / 0.33C cycle stability test. The capacity retention rate after 300 cycles was 87.8%.
[0061] Example 2 The positive electrode active layer was designed with the following proportions: positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PVDF-HFP: nano-ionic conductor LATP, with a ratio of 60%: 32.9%: 0.1%: 2%: 0.5%; the remaining steps were the same as in Example 1; the capacity retention rate was 91.9% after 300 cycles.
[0062] Example 3 The positive electrode active layer was designed with the following proportions: positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PVDF-HFP: nano-ionic conductor LATP ratio of 90%: 6.8%: 2%: 1%: 0.2%; the remaining steps were the same as in Example 1; the capacity retention rate was 89.7% after 300 cycles.
[0063] Example 4 The positive electrode active layer was designed with the following proportions: positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PIB: nano-ionic conductor Li2TiO3 in a ratio of 70%: 26.9%: 1%: 2%: 0.1%; the remaining steps were the same as in Example 1; the capacity retention rate after 300 cycles was 88.3%.
[0064] Example 5 The positive electrode active layer was designed with the following proportions: positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder HNBR: nano-ionic conductor Li2ZrO3 in a ratio of 60%: 39.7%: 0.1%: 0.1%: 0.1%; the remaining steps were the same as in Example 1; the capacity retention rate after 300 cycles was 84.5%.
[0065] Example 6 This example is the same as the steps and formulation in Example 1, except that in step (2), the nano-ion conductor D50 is replaced with 10nm, the glue content is changed to 5%, the viscosity is adjusted to 10mPa·s, the pulse spraying time is 0.1S, the interval time is 1S, the spraying pressure is 2MPa, and the remaining steps are the same as in Example 1. The capacity retention rate after 300 cycles is 86.9%.
[0066] Example 7 This example is the same as the steps and formulation in Example 1, except that in step (2), the nano-ion conductor D50 is replaced with 200nm, the glue content is changed to 1%, the viscosity is adjusted to 50mPa·s, the pulse spraying time is 1S, the interval time is 30S, the spraying pressure is 10MPa, and the remaining steps are the same as in Example 1. The capacity retention rate after 300 cycles is 85.8%.
[0067] Example 8 In this embodiment, the positive electrode active layer was designed with the following proportions: positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PIB: nano-ionic conductor LiNbO3, with a ratio of 75%: 21.5%: 1%: 2%: 0.5%. Compared with Example 1, in step (2), the nano-ionic conductor LiNbO3D50 was replaced with 80nm, the glue content was changed to 1%, the viscosity was adjusted to 50mPa·s, the pulse spraying time was 1S, the interval time was 30S, the spraying pressure was 10MPa, and the remaining steps were the same as in Example 1. The capacity retention rate after 300 cycles was 92.1%.
[0068] Example 9 In this embodiment, the positive electrode active layer is designed with the following proportions: positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PIB: nano-ionic conductor LiNbO3 in a ratio of 80%: 16.5%: 1%: 2%: 0.5%. Compared with Example 1, in step (2), the nano-ionic conductor LiNbO3D50 was replaced with 150nm, the glue content was changed to 1%, the viscosity was adjusted to 50mPa·s, the pulse spraying time was 0.5S, the interval time was 15S, the spraying pressure was 8MPa, and the remaining steps were the same as in Example 1. The capacity retention rate after 300 cycles was 90.8%.
[0069] Example 10 This example uses the same steps and formulation as Example 6, except that the nano-ion conductor D50 is replaced with 9nm, the adhesive content is changed to 5%, the viscosity is adjusted to 10mPa·s, the pulse spraying time is 0.1s, the interval time is 1s, the spraying pressure is 11MPa, and the remaining steps are the same as in Example 1. The capacity retention rate after 300 cycles is 77.6%.
[0070] Example 11 This example is the same as the steps and formulation in Example 1, except that in step (2), the nano-ion conductor D50 is replaced with 220nm, the glue content is changed to 1%, the viscosity is adjusted to 50mPa·s, the pulse spraying time is 1S, the interval time is 30S, the spraying pressure is 1MPa, and the remaining steps are the same as in Example 1. The capacity retention rate after 300 cycles is 73.5%.
[0071] Comparative Example 1 The positive electrode active material NCM811@LATP: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PVDF-HFP ratio is 76%: 20.9%: 1%: 2%; wherein LATP is pre-coated on the surface of NCM particles, and the total content is the same as in Example 1. The mixing steps, time, coating, drying, and roller pressing of the electrode surface are all the same as in Example 1. Half-cells fabricated using the same method were subjected to cycle performance testing. The mold cell was tested at a pressure of 100 MPa and a temperature of 30°C. Cycle stability was tested at 0.33C / 0.33C. After 300 cycles, the capacity retention rate was 83.5%. Figure 4 As shown.
[0072] Comparative Example 2 The positive electrode active material NCM811: sulfide electrolyte Li6PS5Cl: conductive agent VGCF: binder PVDF-HFP: LATP ratio is 76%: 20.9%: 1%: 2%: 0.1%; wherein LATP is not pre-coated on the surface of NCM particles, but is added to the positive electrode slurry in a normal mixing manner, and the mixing steps, time, coating, drying and rolling of the electrode surface capacity are the same as in Example 1; Half-cells made using the same method were subjected to cycle performance testing. The test pressure for the mold cell was 100 MPa, the test temperature was 30℃, and the cycle stability was tested at 0.33C / 0.33C. The capacity retention rate was 73.2% after 300 cycles.
[0073] Table 1. Comparison of test data between the examples and comparative examples Based on the test data from the examples and comparative examples, the electrode prepared by this invention considers the electrochemical stability of sulfide electrolytes at both the material and electrode levels. Compared with traditional positive electrode sheets prepared by simply coating positive electrode particles individually or by directly mixing materials, it can improve the cycle stability of the electrode to a limited extent. Figure 4Compared to Comparative Example 1, in Example 1, because both the slurry and the particle interface contain nano-ionic conductors with low ionic conductivity, the internal resistance is slightly higher than that of the electrode that only coats the positive electrode particles in the early stage of cycling, so the specific capacity is slightly lower in the early stage. However, as cycling progresses, the side reactions of the electrode that only coats the positive electrode particles increase, resulting in its cycling stability being lower than that of the electrode of the present invention. In Comparative Example 2, the nano-ionic conductors are directly added to the slurry, which reduces the uniformity of mixing. Such a low amount of nano-ionic conductors cannot coat the positive electrode particles and electrolyte in a homogenized manner, so the improvement of the interface reaction is very limited, resulting in no fundamental improvement in the cycling decay of the electrode. If too many nano-ionic conductors are added, it will affect the specific capacity of the electrode and increase the internal resistance of the electrode. In Example 10, because the nano-ionic conductor particles are too small and the injection pressure is too high, it causes physical impact damage to the active material. Moreover, at the same content, the smaller the nano-ionic conductor particles, the lower the specific capacity. The increased particle size leads to more physical interfaces, increasing electrode impedance. Under the condition of double negative influence, the cycle stability of the electrode actually deteriorates. In Example 11, due to the excessively large particle size of the nano-ion conductor and the insufficient spraying pressure, it was unable to adhere and effectively form an interface layer. Its test results were similar to those of the ion conductor directly mixed into the slurry in Comparative Example 2. From the results, it can be seen that within the parameter range provided by the present invention, the cycle stability of the sulfide wet-process positive electrode is improved. Furthermore, by combining micro-coating with electrode design and homogenization process, this two-way mixing and coating method results in fewer side reactions during the electrode cycle of the present invention. Therefore, the cycle data is stable and has less fluctuation, simplifying the manufacturing process of the sulfide positive electrode. It also has higher compatibility with the interface buffer conductor. Verifying the influence of the buffer only requires changing the material, without the need for pre-coating, thus improving the optimization efficiency of sulfide at the electrode level and achieving the purpose of the invention.
Claims
1. A positive electrode plate, characterized in that, The positive electrode sheet includes a positive current collector and a positive active material layer located on at least one side of the positive current collector. The positive active material layer includes a positive active material, a positive solid electrolyte, an interface-stabilized ionic conductor, a conductive agent, and a binder. The positive electrode solid electrolyte is a sulfide electrolyte, and the interfacial stable ionic conductor is discontinuously attached between the sulfide electrolyte and the positive electrode active material.
2. The positive electrode sheet according to claim 1, characterized in that, The positive electrode active material is LiNi. x Co y M z O2, wherein M includes at least one of Mn, Al, Zr, Ti, V, Mg, Fe or Mo, 0≤x<1, 0≤y<1, 0≤z<1, and x+y+z=1.
3. The positive electrode sheet according to claim 1, characterized in that, The interface-stabilized ionic conductor material includes Li 1+ x Al x Ti 2-x At least one of the following: (PO4)3, LLZO, LLTO, LAGP, LiPON, Li2TiO3, LiNbO3, Li3BO3, Li2ZrO3, LiCoO3, LiPO3, Al(PO3)3, La(PO3)3, and NaPO3; wherein Li 1+x Al x Ti 2-x In (PO4)3, 0 < x < 1; the particle size range of the interface-stabilized ionic conductor is 10–200 nm.
4. The positive electrode sheet according to claim 1, characterized in that, The sulfide electrolyte is Thio-LISICON, Li 10 GeP2S 12 Li 10 SnP2S 12 Li 7-x PS 6-x M x Li₂S-P₂S₅, Li 10 SiP2S 12 At least one of Li₂S-Si₂S₂ and Li₂S-B₂S₃; wherein Li 7-x PS 6-x M x In this context, M includes at least one of Cl, Br, F, and I, and 0.1 ≤ x ≤ 5.
9.
5. The positive electrode sheet according to claim 1, characterized in that, The mass percentages of the positive electrode active material, positive electrode solid electrolyte, conductive agent, binder, and interface-stabilized ionic conductor material are 60%~90%: 6.5%~39.7%: 0.1%~2%: 0.1%~2%: 0.1%~0.5%.
6. A method for preparing a positive electrode sheet as described in any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: S1. Disperse the positive electrode active material using a solvent to form a homogenate; S2. The atomized interface-stabilized ionic conductor premixed liquid is pulse-sprayed into the stirring positive electrode active material slurry to obtain the first slurry; S3. Add the sulfide electrolyte premix to the first slurry and continue mixing and homogenizing to obtain the second slurry; S4. After adding the conductive agent premix to the second slurry, homogenize the mixture to obtain the third slurry; S5. A third slurry is coated on at least one surface of the positive current collector, and the positive electrode sheet is obtained after drying and rolling.
7. The preparation method according to claim 6, characterized in that, At least one of the interface-stabilized ionic conductor premix, sulfide electrolyte premix, and conductive agent premix contains a binder, wherein the binder has a mass percentage of 0.1-10% in the premix and a solid content of 2-80%.
8. The preparation method according to claim 6, characterized in that, The working viscosity of the interface-stabilized ionic conductor premix is 10~50 mPa·s; the pulse injection pressure is 2~10 MPa; the pulse injection time is 0.1~1 s, and the interval time is 1~30 s.
9. The preparation method according to claim 6, characterized in that, The solvent includes at least one of dichloromethane, tetrahydrofuran, n-hexane, n-heptane, toluene, 2,4-dimethyl-3-pentanone, monochlorobenzene, xylene, toluene, isobutyl isobutyrate, anisole, cyclohexanone, 1,3,5-trimethylbenzene, n-decane, dodecane, and methylformamide.
10. A solid-state battery, the solid-state battery comprising a negative electrode, a positive electrode, and an electrolyte sheet, characterized in that, The positive electrode sheet is the positive electrode sheet according to any one of claims 1 to 5, or the positive electrode sheet prepared by the preparation method according to any one of claims 6 to 9.