An integrated electrode electrolyte membrane, a method for preparing the same, and a battery

Abstract

The application relates to the technical field of batteries, in particular to an integrated electrode electrolyte film, a preparation method thereof and a battery. The application provides a preparation method of an integrated electrode electrolyte film, which comprises the following steps: coating mixed slurry on a substrate to obtain a wet film; and performing static placement on the wet film; wherein the mixed slurry comprises electrode material and polymer electrolyte precursor slurry; and performing partition curing on the wet film after the static placement to obtain the integrated electrode electrolyte film. By adopting an electrode material and polymer electrolyte slurry one-step in-situ forming process, interface impedance is significantly reduced, interface stability is improved, battery cycle performance and safety are obviously improved, and the preparation process is simplified.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to an integrated electrode electrolyte membrane, its preparation method, and a battery. Background Technology

[0002] Currently, the fabrication of solid-state batteries typically requires the separate fabrication of electrodes (positive or negative electrodes) and solid electrolyte membranes, followed by the composite bonding of the two. Taking the fabrication of silicon negative electrodes as an example, the process includes: pre-composite bonding, which involves mixing silicon materials, binders, and conductive agents to form a negative electrode sheet, and then pressing it together with a separate electrolyte membrane; and surface treatment, which involves coating the surface of the formed negative electrode sheet with a polymer layer to stabilize the interface.

[0003] In addition, existing technologies also include methods for modifying electrode active materials by double-layer electrolyte coating, such as coating solid electrolyte and organic conductive polymer on the surface of polyanionic materials; and methods for preparing integrated positive electrodes by using double-layer coating and curing processes, such as sequentially coating positive electrode active layer and solid electrolyte layer on positive electrode current collector; however, true integrated molding of electrode and electrolyte has not yet been achieved, and the adaptability to changes in electrode volume is insufficient.

[0004] The above method has the following problems: Poor solid-solid interface contact: The electrode layer and the electrolyte layer are formed independently and then bonded together. The microscopic contact is insufficient, resulting in high interface impedance. This is especially true in scenarios where the silicon anode expands rapidly, and the interface deteriorates more severely during cycling. Although partial coating modification or layered coating methods optimize the surface interface, they do not form an overall gradient structure, and the interface bonding force is still weak.

[0005] Interface failure is extremely easy: The silicon anode undergoes huge volume changes (>300%) during cycling, which can quickly destroy the rigid interface, generate cracks, and cause the electrode to physically separate from the electrolyte, resulting in rapid battery degradation.

[0006] Gas generation and safety issues: Interface cracks become channels for side reactions. The SEI formed on the negative electrode side will continuously consume lithium source and generate gas as it breaks down and regenerates. Oxygen on the positive electrode side may also diffuse along the cracks to the negative electrode reaction, accelerating performance degradation and causing safety issues.

[0007] Complex process: The multi-step preparation and composite process is inefficient, requires large equipment investment, and is costly.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] The primary objective of this invention is to provide a method for preparing an integrated electrode electrolyte membrane. By employing a one-step in-situ molding process of electrode materials and polymer electrolyte slurry, the interfacial impedance is significantly reduced, the interfacial stability is improved, the battery cycle performance and safety are significantly enhanced, and the preparation process is simplified.

[0010] A second objective of the present invention is to provide an integrated electrode electrolyte membrane.

[0011] A third objective of this invention is to provide a battery.

[0012] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a method for preparing an integrated electrode electrolyte membrane, comprising the following steps: A mixed slurry is coated onto a substrate to obtain a wet film; the wet film is then allowed to stand; wherein the mixed slurry comprises an electrode material and a polymer electrolyte precursor slurry; The wet film, after being left to stand, is cured in sections to obtain the integrated electrode electrolyte membrane.

[0013] Furthermore, the electrode material includes an electrode active material or an electrode active material with a surface pretreatment layer; And / or, the particle size of the electrode material is 1-20 μm.

[0014] Furthermore, it includes at least one of the following features (1) to (4); (1) The electrode active material includes a positive electrode active material or a negative electrode active material; (2) The pretreatment layer includes at least one of oxide electrolyte, polymer electrolyte and sulfide solid electrolyte; (3) The thickness of the pretreatment layer is 1-100 nm; (4) The method of surface coating pretreatment layer includes at least one of sol-gel method, atomic layer deposition method, chemical vapor deposition method, in-situ polymerization method, in-situ conversion method and liquid phase deposition method.

[0015] Furthermore, when the electrode active material is a positive electrode active material, the pretreatment layer includes at least one of lithium phosphate, lithium aluminate, lithium titanium aluminum phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanate, lithium phosphorus sulfur chloride, polyethylene oxide lithium-conducting composite polymer electrolyte, and polyaniline polymer electrolyte. And / or, when the electrode active material is a negative electrode active material, the pretreatment layer includes at least one of lithium phosphorus oxynitride, lithium phosphate, lithium lanthanum zirconium titanate, and polyethylene glycol diacrylate-based composite polymer electrolyte.

[0016] Furthermore, the polymer electrolyte precursor slurry comprises: a film-forming material, a lithium salt, an initiator, and a solvent; And / or, the mass ratio of the electrode material to the polymer electrolyte precursor slurry is (1-5):1.

[0017] Furthermore, it includes at least one of the following features (1) to (4); (1) The film-forming material includes at least one of polyethylene glycol diacrylate and its derivatives, polyethylene oxide and its derivatives, vinylene carbonate and its derivatives, trimethylolpropane triacrylate and its derivatives, and polyvinylidene fluoride and its derivatives; (2) The content of the film-forming material in the polymer electrolyte precursor slurry is 20wt%-60wt%; (3) The mass of the lithium salt is 5%-30% of the mass of the film-forming material; (4) The mass of the initiator is 0.1%-3% of the mass of the film-forming material.

[0018] Furthermore, it includes at least one of the following features (1) to (3); (1) The coating process further includes: prepolymerizing the mixed slurry to adjust the viscosity of the mixed slurry; the prepolymerization temperature is 40-70℃ and the time is 2-10min; the viscosity of the mixed slurry after prepolymerization is 1000-5000cP; (2) The thickness of the wet film is 50-500 μm; (3) The conditions for standing are: temperature 15-40℃, relative humidity ≤40%, and time 1-30min.

[0019] Further, the partitioned curing includes: heating the side of the wet film closest to the substrate at temperature T1, and heating the side furthest from the substrate at temperature T2; 50℃≤T1<70℃, 70℃≤T2≤100℃; And / or, the curing time of the partition is 2-24 hours.

[0020] Secondly, the present invention also provides an integrated electrode electrolyte membrane, which is prepared by the method described above.

[0021] Thirdly, the present invention also provides a battery comprising an integrated electrode electrolyte membrane as described above.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention achieves integrated electrode and electrolyte molding by employing a one-step in-situ molding process for electrode materials and polymer electrolyte slurry. This eliminates the problem of poor contact at the electrode-electrolyte interface from the source, significantly reduces interfacial impedance, and improves charge transport efficiency. It effectively buffers the volume expansion of electrode materials (especially silicon anodes), maintains interface structural stability, and greatly improves cycle life. The dense integrated structure can also effectively block crosstalk between positive and negative electrodes, reduce the risk of side reaction gas generation and thermal runaway, and improve battery safety. In addition, this method eliminates the need for separate electrolyte membrane preparation and subsequent composite processes, and does not require the addition of additional conductive agents and binders. The one-step process simplifies the production process, reduces manufacturing costs, and is applicable to various positive and negative electrode active material systems, providing a universal solution for the integrated electrode-electrolyte preparation of solid-state batteries. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic flowchart of the preparation method of the integrated electrode electrolyte membrane of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0026] See Figure 1 In some embodiments of the present invention, a method for preparing an integrated electrode electrolyte membrane is provided, comprising the following steps: The mixed slurry is coated onto a substrate to obtain a wet film; the wet film is then allowed to stand; wherein, the mixed slurry includes electrode material and polymer electrolyte precursor slurry; The wet film after standing is cured in sections to obtain an integrated electrode electrolyte membrane.

[0027] The method for preparing the integrated electrode electrolyte membrane of the present invention involves a one-step in-situ molding process that mixes electrode materials with polymer electrolyte precursor slurry, followed by coating, static settling, and partitioned curing to form an integrated electrode electrolyte membrane with a longitudinal gradient structure.

[0028] Through the "integrated molding" in-situ polymerization process, the polymer electrolyte precursor is polymerized in situ on the surface and between the electrode material particles, achieving an integrated connection between the electrode and the electrolyte, forming a continuous ion transport network from the electrode to the electrolyte. This solves the problem of poor solid-solid interface contact between the electrode and the electrolyte, significantly reduces interface impedance, and improves charge transport efficiency.

[0029] The flexible polymer network in the integrated electrode-electrolyte membrane structure can effectively buffer stress and maintain a lasting contact between electrode particles and electrolyte; it can effectively buffer the volume expansion of electrode materials, adapt to changes in electrode volume, and maintain the stability of the interface structure; it is especially suitable for anode materials with large volume changes, such as silicon anodes, and can significantly improve the cycle life of silicon anodes.

[0030] The dense, integrated structure of the integrated electrode electrolyte membrane can effectively physically block crosstalk between the positive and negative electrodes (such as oxygen), reduce side reaction gas production and contact reactions of active materials, and block the diffusion paths of gas production and side reactions; thus reducing the safety risks of battery thermal runaway, short circuits, etc., and improving battery safety.

[0031] The integrated electrode electrolyte membrane preparation method eliminates the need for separate electrolyte membrane preparation and subsequent composite processes. The one-step process greatly simplifies the production process and reduces manufacturing costs. It also reduces the use of conductive agents and binders, thus lowering raw material costs. Furthermore, it greatly simplifies the full cell stacking process, providing a simple integrated electrode electrolyte membrane preparation method for both the positive and negative electrodes, thereby simplifying full cell assembly.

[0032] The method for preparing an integrated electrode-electrolyte membrane does not depend on the intrinsic chemical properties of the electrode material and is applicable to a variety of positive and negative electrode material systems. It provides a general solution for the integrated preparation of electrode-electrolyte membranes in solid-state batteries and expands the application scenarios.

[0033] In some embodiments of the present invention, the electrode material includes an electrode active material or an electrode active material with a surface pretreatment layer; preferably, it is an electrode active material with a surface pretreatment layer; the preparation method is to pretreat the electrode active material to form a pretreatment layer on the surface of the electrode active material.

[0034] The pretreatment layer in the electrode active material with a surface coating pretreatment layer works synergistically with the flexible polymer network to further buffer stress and maintain a lasting contact between electrode particles and electrolyte; it effectively buffers the volume expansion of the electrode material, adapts to changes in electrode volume, and maintains the stability of the interface structure.

[0035] In some embodiments of the present invention, the particle size of the electrode material is 1-20 μm.

[0036] In some embodiments of the present invention, the electrode active material includes a positive electrode active material or a negative electrode active material.

[0037] In some embodiments of the present invention, the pretreatment layer includes at least one of oxide electrolyte, polymer electrolyte, and sulfide solid electrolyte; Preferably, the oxide electrolyte includes at least one of lithium phosphate (Li3PO4), lithium aluminate (LiAlO2), lithium titanium aluminum phosphate, lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium titanate (LLZTO), and lithium phosphorus oxynitride (LiPON). Polymer electrolytes include polyethylene oxide (PEO)-based lithium-conducting composite polymer electrolytes, polyaniline (PANI) polymer electrolytes, and polyethylene glycol diacrylate (PEGDA)-based composite polymer electrolytes; Sulfide solid electrolytes include at least one of lithium germanium phosphorus sulfide (LGPS), lithium phosphorus sulfide (LPS), and lithium phosphorus sulfide chloride (LPSC).

[0038] In some embodiments of the present invention, the thickness of the pretreatment layer is 1-100 nm.

[0039] This invention selects positive or negative electrode active materials within a specific particle size range and pre-constructs a pre-treatment layer on their surface; wherein the pre-treatment layer components adapted to the positive electrode active material and the pre-treatment layer components adapted to the negative electrode active material are designed in a matching manner. The adapted pre-treatment layer is preferably a fast ion conductor oxide electrolyte or a conductive composite polymer electrolyte.

[0040] In some embodiments of the present invention, the positive electrode active material includes at least one selected from lithium transition metal oxide, lithium nickel cobalt aluminum oxide (NCA), lithium iron phosphate (LFP), and polyanionic materials; the lithium transition metal oxide includes LiNi x Co y Mn 1-x-y O2 (0≤x≤1, 0≤y≤1, and x+y≤1) and / or LiCoO2.

[0041] In some embodiments of the present invention, the particle size of the positive electrode active material is 2-20 μm; typically, but not limitingly, for example, the particle size of the positive electrode active material can be 2 μm, 10 μm, 15 μm, 20 μm, and any value between any two of these.

[0042] In some embodiments of the present invention, when the electrode active material is a positive electrode active material, the pretreatment layer includes, but is not limited to, at least one of lithium phosphate (Li3PO4), lithium aluminate (LiAlO2), lithium titanium aluminum phosphate, lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium titanate (LLZTO), lithium phosphorus sulfur chloride (LPSC), polyethylene oxide (PEO) based lithium conductive composite polymer electrolyte and polyaniline (PANI) polymer electrolyte.

[0043] In some embodiments of the present invention, when the electrode active material is a positive electrode active material, the thickness of the pretreatment layer is 1-50 nm; typically, but not limitingly, for example, when the electrode active material is a positive electrode active material, the thickness of the pretreatment layer can be 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm and any value between any two of these.

[0044] In some embodiments of the present invention, the negative electrode active material includes at least one of silicon-based materials, lithium metal and its composites, and lithium titanate (LTO); preferably, the silicon-based material includes silicon particles and / or silicon-carbon composites.

[0045] In some embodiments of the present invention, the particle size of the negative electrode active material is 1-10 μm; typically, but not limitingly, for example, the particle size of the negative electrode active material can be 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm and any value between any two of these.

[0046] In some embodiments of the present invention, when the electrode active material is a negative electrode active material, the pretreatment layer includes, but is not limited to, at least one of lithium phosphorus oxynitride (LiPON), lithium phosphate (Li3PO4), lithium lanthanum zirconium titanate (LLZTO), and polyethylene glycol diacrylate (PEGDA) based composite polymer electrolyte.

[0047] In some embodiments of the present invention, when the electrode active material is a negative electrode active material, the thickness of the pretreatment layer is 1-100 nm; typically, but not limitingly, for example, when the electrode active material is a negative electrode active material, the thickness of the pretreatment layer can be 1 nm, 10 nm, 20 nm, 40 nm, 60 nm, 80 nm, 100 nm and any value between any two of these.

[0048] In some embodiments of the present invention, the method for surface coating pretreatment layer (pretreatment method) includes at least one of the following: sol-gel method, atomic layer deposition (ALD) method, chemical vapor deposition (CVD) method, in-situ polymerization method, in-situ conversion method, and liquid phase deposition method. The in-situ conversion method involves reacting the electrode material with a substance to generate an in-situ conversion layer on the surface of the electrode material. The present invention does not strictly limit the method for surface coating pretreatment layer; as long as a continuous and dense pretreatment layer can be formed on the surface of the electrode active material, the same interface optimization effect can be achieved.

[0049] This invention forms a pretreatment layer on the surface of the electrode active material, that is, a pretreatment layer is coated on the electrode material, which provides a preliminary ion transport channel; improves the compatibility and interfacial stability between the electrode active material and the subsequent bulk polymer electrolyte; and isolates the electrode active material from the side reactions that may occur if there is direct contact between the electrode active material and the subsequent bulk polymer electrolyte.

[0050] In some embodiments of the present invention, the polymer electrolyte precursor slurry includes: a film-forming material, a lithium salt, an initiator, and a solvent; preferably, the film-forming material includes a monomer and / or a prepolymer.

[0051] In some embodiments of the present invention, the mass ratio of electrode material to polymer electrolyte precursor slurry is (1-5):1; typically, but not limitingly, for example, the mass ratio of electrode material to polymer electrolyte precursor slurry can be 1:1, 2:1, 3:1, 4:1, 5:1, and any value between any two thereof.

[0052] In some embodiments of the present invention, the film-forming material includes at least one of polyethylene glycol diacrylate (PEGDA) and its derivatives, polyethylene oxide (PEO) and its derivatives, vinylene carbonate (VC) and its derivatives, trimethylolpropane triacrylate (TMPTA) and its derivatives, and polyvinylidene fluoride (PVDF) and its derivatives.

[0053] In some embodiments of the present invention, the content of film-forming material in the polymer electrolyte precursor slurry is 20wt%-60wt%; typically, but not limitingly, for example, the content of film-forming material in the polymer electrolyte precursor slurry can be 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, and any value between any two thereof.

[0054] In some embodiments of the present invention, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium di(oxalato)borate (LiBOB), and lithium di(fluorooxalato)borate (LiODFB).

[0055] In some embodiments of the invention, the mass of the lithium salt is 5%-30% of the mass of the film-forming material; typically, but not limitingly, for example, the mass of the lithium salt is 5%, 10%, 15%, 20%, 25%, 30% of the mass of the film-forming material, and a range between any two thereof.

[0056] In some embodiments of the present invention, the initiator includes a thermal initiator and / or a photoinitiator; preferably, the initiator includes azobisisobutyronitrile (AIBN) and / or benzoyl peroxide (BPO).

[0057] In some embodiments of the invention, the mass of the initiator is 0.1%-3% of the mass of the film-forming material; typically, but not limitingly, for example, the mass of the initiator is 0.1%, 0.5%, 1%, 2%, 3% of the mass of the film-forming material, and any value between any two thereof.

[0058] In some embodiments of the present invention, the solvent includes at least one of acetonitrile, N-methylpyrrolidone (NMP) and dimethyl carbonate (DMC); an appropriate amount of solvent is added to adjust the viscosity of the slurry.

[0059] In some embodiments of the present invention, the method for preparing the mixed slurry includes: mixing electrode material and polymer electrolyte precursor slurry.

[0060] In some embodiments of the present invention, the coating process further includes: prepolymerizing the mixed slurry to adjust the viscosity of the mixed slurry.

[0061] In some embodiments of the present invention, the prepolymerization temperature is 40-70°C and the time is 2-10 min; typically, but not limitingly, for example, the prepolymerization temperature can be 40°C, 50°C, 60°C, 70°C and any value between any two of these; the prepolymerization time can be 2 min, 4 min, 6 min, 8 min, 10 min and any value between any two of these.

[0062] In some embodiments of the invention, the viscosity of the prepolymerized slurry is 1000-5000 cP; typically, but not limitingly, for example, the viscosity of the prepolymerized slurry can be 1000 cP, 2000 cP, 3000 cP, 4000 cP, 5000 cP, and any value between two of these. The viscosity is tested at a temperature of 25 ± 0.5 °C.

[0063] When the viscosity of the mixed slurry is suitable and the polymer itself is viscous, prepolymerization is not necessary.

[0064] By designing the composition of the polymer electrolyte precursor slurry, the compatibility between the electrode material and the electrolyte is improved, avoiding side reactions. Mixed slurry formulations can be designed according to the target performance of the positive and negative electrodes. No additional conductive agents or binders for the electrode materials need to be added during the preparation of the mixed slurry. Through surface coating of the electrode material and the composition design of the polymer electrolyte precursor slurry, the conductivity and structural adhesion of the electrode are achieved, simplifying the process and reducing costs.

[0065] Electrode materials and polymer electrolyte precursor slurries are mixed, and the mixed slurries are prepolymerized. By controlling the temperature and time of prepolymerization, the degree of crosslinking of the mixed slurry is adjusted, and the viscosity of the mixed slurry is precisely controlled to the optimal process window, providing a process basis for subsequent coating uniformity and static settling.

[0066] In some embodiments of the present invention, the coating method includes blade coating, spray coating, slot coating, or gravure coating. The present invention does not strictly limit the coating method, as long as the uniformity of the wet film can be guaranteed and the subsequent static settling and zone curing process parameters are not changed, the same longitudinal gradient structure can be formed.

[0067] In some embodiments of the present invention, the substrate includes a current collector; preferably, the substrate includes a positive current collector or a negative current collector; more preferably, the positive current collector includes, but is not limited to, aluminum foil and its composite current collector; the negative current collector includes, but is not limited to, copper foil and its composite current collector. In addition to positive / negative current collectors, other substrates may also be used.

[0068] In some embodiments of the invention, the thickness of the wet film is 50-500 μm; typically, but not limitingly, for example, the thickness of the wet film can be 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 300 μm, 400 μm, 500 μm, and any two of these ranges.

[0069] In some embodiments of the present invention, the conditions for settling are: temperature of 15-40°C, relative humidity ≤40%, and time of 1-30 min; typically, but not limitingly, for example, the settling temperature can be 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, and any two of these values; the settling time can be 1 min, 5 min, 10 min, 20 min, 30 min, and any two of these values.

[0070] By utilizing the density difference between the electrode material and the polymer electrolyte precursor slurry, the electrode material particles are orderly settled and enriched on the side close to the substrate (current collector), while the polymer electrolyte precursor slurry floats to the side away from the substrate (current collector), forming a preliminary vertical composition gradient.

[0071] In addition to using gravity to allow sedimentation, centrifugal force, magnetic field, or electric field can also be used to assist or accelerate the orderly arrangement and gradient formation of particles to adapt to materials with different densities and magnetic properties.

[0072] In some embodiments of the present invention, partitioned curing includes: heating the side of the wet film closest to the substrate at temperature T1, and heating the side furthest from the substrate at temperature T2; 50°C ≤ T1 < 70°C, 70°C ≤ T2 ≤ 100°C; typically, but not limitingly, for example, T1 can be any value between 50°C, 55°C, 60°C, 65°C, and any two thereof; T2 can be any value between 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, and any two thereof.

[0073] In some embodiments of the present invention, the curing time for each zone is 2-24 hours; typically, but not limitingly, for example, the curing time for each zone can be 2 hours, 5 hours, 10 hours, 15 hours, 20 hours, 24 hours, and any value between any two of these.

[0074] Differential heating and curing are applied to the upper and lower surfaces of the wet film. After curing, the solvent completely evaporates, and the film-forming material fully polymerizes, forming an integrated polymer electrode-electrolyte membrane with a longitudinal gradient structure. The specific differential heating and curing temperature parameters are as follows: the side of the wet film closer to the substrate is the lower heating zone, using a lower temperature (50℃≤T1<70℃). At this temperature range, the polymerization reaction is gradual, ultimately forming a flexible polymer in the electrode material particle-rich area. This flexible polymer has low cross-linking degree and high flexibility. This flexible polymer, in synergy with the electrode material, can more effectively adapt to volume changes and maintain tight interfacial contact. The side of the wet film farther from the substrate is the upper heating zone, using a higher temperature (70℃≤T2≤100℃). At this temperature range, the polymerization reaction is complete, forming a polymer electrolyte-rich area with high cross-linking degree and high ionic conductivity, resulting in a dense polymer electrolyte bulk layer.

[0075] In some embodiments of the present invention, zone curing includes at least one of oven heating, infrared heating, and air heating. The present invention does not strictly limit the heating method for zone curing; as long as differentiated temperature control of the upper and lower surfaces of the wet film can be achieved, a gradient distribution of the polymer crosslinking degree can be realized. Besides the above-mentioned zone curing, a combination of "photocuring + thermal curing" can also be used; for example, first, ultraviolet light is used to irradiate from the side away from the substrate to rapidly cure and form a dense polymer electrolyte; then, heating is used to slowly cure the side closer to the substrate to form a flexible polymer.

[0076] This invention achieves the following beneficial effects through the synergistic combination of electrode materials and polymer electrolyte precursor slurry in a one-step process chain: Nanoscale-microscale multi-level interface construction: The nanoscale surface pretreatment layer optimizes the microscopic contact between the electrode and electrolyte, reducing the initial interfacial impedance; the microscale vertical gradient polymer structure macroscopically ensures the mechanical integrity and ion transport efficiency of the entire electrode-electrolyte system. The synergistic effect of both significantly alleviates interfacial problems. Nanoscale surface pretreatment and microscale vertical gradient structures address the interfacial contact, stress buffering, and material barrier issues of solid-state batteries in a hierarchical and synergistic manner, fundamentally improving interfacial stability.

[0077] Quantitative design of prepolymerization control: "Prepolymerization control" ensures that the mixed slurry has the best rheological properties, so that "static settling" can achieve a stable, controllable and repeatable longitudinal gradient distribution of components, avoiding excessively fast or non-settling of particles.

[0078] Controllable sedimentation parameter limitation: By adjusting the settling time, the electrode material particles are orderly enriched on the substrate (current collector) side, forming an electrode material enrichment zone of appropriate thickness. This not only ensures the active material loading of the electrode, but also avoids the increase in interfacial impedance caused by particle dispersion, and provides a reasonable structural basis for zoned curing.

[0079] The partitioned curing process achieves an integrated membrane with functional zones: a membrane layer integrating the electrode material enrichment zone and the polymer electrolyte enrichment zone with high ionic conductivity is constructed simultaneously in situ, optimizing the interfacial mechanical properties of the electrode material enrichment zone (electrode side) and the bulk transport properties of the polymer electrolyte enrichment zone (electrolyte side).

[0080] One-step process and universal design: The one-step process of "surface coating pretreatment layer + prepolymerization and controllable adhesion + controllable sedimentation + zoned curing" relies on the difference in physical state between electrode material particles and polymer electrolyte precursor slurry to integrate electrode preparation and electrolyte membrane forming into a single process. It eliminates the need for additional conductive agents and binders, simplifying the production process and reducing raw material and process costs. At the same time, the process does not depend on the intrinsic chemical properties of the electrode material. It can be adapted to a variety of positive and negative electrode materials simply by matching the composition and parameters, achieving the universality of the process and expanding the application scenarios.

[0081] This invention clarifies the full quantitative parameters of a one-step process chain of "surface coating pretreatment layer + prepolymerization control + controllable settling + zone curing", including pretreatment layer thickness, slurry composition ratio, prepolymerization temperature and time, settling time, zone curing temperature and time, etc., realizing the repeatable and scalable production of vertical gradient structures and solving the problem of poor stability of existing processes.

[0082] This invention achieves multi-level optimization from nano-interface to macro-gradient structure through nano-modification of materials and full-process quantitative control of the process. It fundamentally solves the electrode-electrolyte interface problem of existing solid-state batteries, while taking into account the simplification and universality of the process, and ultimately achieves simultaneous improvement in battery electrochemical performance, safety and production economy.

[0083] The method for preparing the integrated electrode-electrolyte membrane of the present invention is not only applicable to liquid / gel / solid batteries, but also to the preparation of capacitor electrodes or other electrochemical devices; it can serve as both an electrode and an electrolyte membrane, and only one other electrode is needed to form a battery; additional electrodes or electrolyte layers can also be added on this basis, and the integrated electrode-electrolyte membrane can serve as an interface buffer layer, for example, a battery can be formed by separate positive and negative electrodes and the integrated electrode-electrolyte membrane, or a battery can be formed by the integrated electrode-electrolyte membrane, other electrolyte membranes and another electrode.

[0084] In some embodiments of the present invention, an integrated electrode electrolyte membrane is also provided, which is prepared by the above-described method for preparing an integrated electrode electrolyte membrane.

[0085] In some embodiments of the present invention, the integrated electrode electrolyte membrane has a compositional gradient in the longitudinal (thickness direction).

[0086] In some embodiments of the present invention, the side of the integrated electrode electrolyte membrane closer to the substrate is an electrode material enrichment region, and the side farther from the substrate is a polymer electrolyte enrichment region; wherein, the electrode material enrichment region includes electrode material and flexible polymer; and the polymer electrolyte enrichment region includes polymer electrolyte.

[0087] In some embodiments of the present invention, the integrated electrode electrolyte membrane includes an integrated positive electrode electrolyte membrane or an integrated negative electrode electrolyte membrane.

[0088] In some embodiments of the present invention, a battery is also provided, including the above-described integrated electrode electrolyte membrane; preferably, the battery includes a solid-state battery.

[0089] In some embodiments of the present invention, the solid-state battery includes an integrated positive electrode electrolyte membrane and a graphite negative electrode; or, the solid-state battery includes a positive electrode and an integrated negative electrode electrolyte membrane, wherein the positive electrode includes a ternary NCM positive electrode sheet or an LFP positive electrode sheet.

[0090] Example 1 The method for preparing the integrated positive electrode electrolyte membrane provided in this embodiment includes the following steps: S1. Pre-treat the positive electrode active material to obtain a positive electrode active material with a pre-treated surface coating; the pre-treatment steps are as follows: using the sol-gel method on LiNi with a particle size of 5μm. 0.8 Co 0.1Mn 0.1 A Li3PO4 layer with a thickness of 2-10 nm is formed on the surface of the O2 (NCM811) positive electrode active material; S2. After mixing the positive electrode active material with the pretreated surface layer and the polymer electrolyte precursor slurry, a mixed slurry is obtained; the mixed slurry is prepolymerized at 55°C for 3 minutes to make the viscosity of the mixed slurry 2500 cP. The polymer electrolyte precursor slurry, by mass percentage, comprises: 40% PEGDA, 10% LiPF6, 1% BPO, and 49% DMC; the mass ratio of the positive electrode active material with the surface-coated pretreatment layer to the polymer electrolyte precursor slurry is 3:1. S3. Coat the prepolymerized mixed slurry onto aluminum foil to obtain a wet film with a thickness of 200 μm; let the wet film stand for 3 min at 25±2℃ and relative humidity ≤40%; S4. The wet film after standing is cured in sections. The steps of section curing are as follows: the wet film is heated in an oven at 55°C on the side close to the aluminum foil and at 75°C on the side away from the aluminum foil. After 8 hours, the section curing is completed and an integrated positive electrode electrolyte membrane is obtained.

[0091] Example 2 The method for preparing the integrated negative electrode electrolyte membrane provided in this embodiment includes the following steps: S1. The negative electrode active material is pretreated to obtain a negative electrode active material with a pretreated layer on the surface. The pretreatment steps are as follows: a lithium phosphorus oxynitride (LiPON) layer with a thickness of 20 nm is formed on the surface of silicon particles with a particle size of 5 μm using atomic layer deposition (ALD). S2. After mixing the negative electrode active material with the pretreated surface layer and the polymer electrolyte precursor slurry, a mixed slurry is obtained; the mixed slurry is prepolymerized at 65°C for 5 minutes to make the viscosity of the mixed slurry 2600 cP. The polymer electrolyte precursor slurry, by mass percentage, comprises: 30% PVDF, 12% LiTFSI, 2% AIBN, and 56% NMP; the mass ratio of the anode active material with a surface-coated pretreatment layer to the polymer electrolyte precursor slurry is 4:1. S3. Coat the prepolymerized mixed slurry onto copper foil to obtain a wet film with a thickness of 120 μm; let the wet film stand for 4 min at 25±2℃ and relative humidity ≤40%; S4. The wet film after standing is cured in sections. The steps of section curing are as follows: the wet film is heated in an oven at 65°C on the side close to the copper foil and at 85°C on the side away from the copper foil. After 12 hours, the section curing is completed and an integrated negative electrode electrolyte membrane is obtained.

[0092] Example 3 The method for preparing the integrated positive electrode electrolyte membrane provided in this embodiment includes the following steps: S1. The positive electrode active material is pretreated to obtain a positive electrode active material with a pretreated surface coating; the pretreatment steps are as follows: atomic layer deposition (ALD) is used to deposit a pretreated layer on LiNi with a particle size of 8 μm. 0.8 Co 0.1 Mn 0.1 A 10-12 nm thick PANI polymer electrolyte layer is formed on the surface of the O2 (NCM811) positive electrode active material; S2. After mixing the positive electrode active material with the pretreated surface layer and the polymer electrolyte precursor slurry, a mixed slurry is obtained; the mixed slurry is prepolymerized at 60°C for 4 minutes to make the viscosity of the mixed slurry 2000 cP. The polymer electrolyte precursor slurry, by mass percentage, comprises: 45% TMPTA, 8% LiFSI, 1.5% AIBN, and 45.5% NMP; the mass ratio of the positive electrode active material with the surface-coated pretreatment layer to the polymer electrolyte precursor slurry is 2.5:1. S3. Coat the prepolymerized mixed slurry onto aluminum foil to obtain a wet film with a thickness of 160 μm; let the wet film stand for 5 min at 25±2℃ and relative humidity ≤40%; S4. The wet film after standing is cured in sections. The steps of section curing are as follows: the wet film is heated in an oven at 65°C on the side close to the aluminum foil and at 80°C on the side away from the aluminum foil. After 10 hours, the section curing is completed and an integrated positive electrode electrolyte membrane is obtained.

[0093] Example 4 The method for preparing the integrated positive electrode electrolyte membrane provided in this embodiment includes the following steps: S1. The positive electrode active material is pretreated to obtain a positive electrode active material with a pretreated layer on the surface. The pretreatment steps are as follows: an LPSC layer with a thickness of 15-20nm is formed on the surface of NCA positive electrode active material with a particle size of 12μm by in-situ polymerization. S2. After mixing the positive electrode active material with the pretreated surface layer and the polymer electrolyte precursor slurry, a mixed slurry is obtained; the mixed slurry is prepolymerized at 50°C for 6 minutes to make the viscosity of the mixed slurry 1800 cP. The polymer electrolyte precursor slurry, by mass percentage, comprises: VC 40%, LiPF6 10%, BPO 1%, and DMC 49%; the mass ratio of the positive electrode active material with the surface-coated pretreatment layer to the polymer electrolyte precursor slurry is 3.5:1. S3. Coat the prepolymerized mixed slurry onto aluminum foil to obtain a wet film with a thickness of 130 μm; let the wet film stand for 8 min at 25±2℃ and relative humidity ≤40%; S4. The wet film after standing is cured in sections. The steps of section curing are as follows: the wet film is heated in an oven at 62°C on the side close to the aluminum foil and at 100°C on the side away from the aluminum foil. After 15 hours, the section curing is completed and an integrated positive electrode electrolyte membrane is obtained.

[0094] Example 5 The method for preparing the integrated positive electrode electrolyte membrane provided in this embodiment includes the following steps: S1. The positive electrode active material is pretreated to obtain a positive electrode active material with a pretreated layer on the surface. The pretreatment steps are as follows: an LLZO layer with a thickness of 60 nm is formed on the surface of the LiCoO2 positive electrode active material with a particle size of 10 μm by in-situ polymerization. S2. After mixing the positive electrode active material with the pretreated surface layer and the polymer electrolyte precursor slurry, a mixed slurry is obtained; the mixed slurry is prepolymerized at 70°C for 3 minutes to make the viscosity of the mixed slurry 3500 cP. The polymer electrolyte precursor slurry, by mass percentage, comprises: 40% PEGDA, 15% LiTFSI, 2% BPO, and 43% NMP; the mass ratio of the positive electrode active material with the surface-coated pretreatment layer to the polymer electrolyte precursor slurry is 4.5:1. S3. Coat the prepolymerized mixed slurry onto aluminum foil to obtain a wet film with a thickness of 130 μm; let the wet film stand for 6 min at 25±2℃ and relative humidity ≤40%; S4. The wet film after standing is cured in sections. The steps of section curing are as follows: the wet film is heated in an oven at 60°C on the side close to the aluminum foil and at 80°C on the side away from the aluminum foil. After 15 hours, the section curing is completed and an integrated positive electrode electrolyte membrane is obtained.

[0095] Example 6 The method for preparing the integrated negative electrode electrolyte membrane provided in this embodiment includes the following steps: S1. The negative electrode active material is pretreated to obtain a negative electrode active material with a pretreated layer on the surface. The pretreatment steps are as follows: an LLZTO layer with a thickness of 70nm is formed on the surface of silicon particles with a particle size of 7μm using the sol-gel method. S2. After mixing the negative electrode active material with the pretreated surface layer and the polymer electrolyte precursor slurry, a mixed slurry is obtained; the mixed slurry is prepolymerized at 55°C for 7 minutes to make the viscosity of the mixed slurry 2800 cP. The polymer electrolyte precursor slurry, by mass percentage, comprises: PEO 38%, LiODFB 10%, AIBN 1%, and DMC 51%; the mass ratio of the anode active material with the surface-coated pretreatment layer to the polymer electrolyte precursor slurry is 3:1. S3. Coat the prepolymerized mixed slurry onto copper foil to obtain a wet film with a thickness of 100 μm; let the wet film stand for 10 min at 25±2℃ and relative humidity ≤40%; S4. The wet film after standing is cured in sections. The steps of section curing are as follows: the wet film is heated in an oven at 50°C on the side close to the copper foil and at 95°C on the side away from the copper foil. After 18 hours, the section curing is completed and an integrated negative electrode electrolyte membrane is obtained.

[0096] Example 7 The preparation method of the integrated positive electrode electrolyte membrane provided in this embodiment is the same as that in Embodiment 1, except that step S1 is omitted, and LiNi with a particle size of 5 μm is directly applied. 0.8 Co 0.1 Mn 0.1 O2 (NCM811) positive electrode active material and polymer electrolyte precursor slurry are mixed.

[0097] Example 8 The method for preparing the integrated positive electrode electrolyte membrane provided in this embodiment includes the following steps: S1. Pre-treat the positive electrode active material to obtain a positive electrode active material with a pre-treated surface coating; the pre-treatment steps are as follows: using the sol-gel method on LiNi with a particle size of 5μm. 0.8 Co 0.1 Mn 0.1 A Li3PO4 layer with a thickness of 2-10 nm is formed on the surface of the O2 (NCM811) positive electrode active material; S2. After mixing the positive electrode active material with the pretreated surface layer and the polymer electrolyte precursor slurry, a mixed slurry (viscosity 3000 cP) is obtained. The polymer electrolyte precursor slurry, by mass percentage, comprises: 35% PVDF, 12% LiTFSI, 2% AIBN, and 51% NMP; the mass ratio of the positive electrode active material with the surface-coated pretreatment layer to the polymer electrolyte precursor slurry is 4:1. S3. Coat the mixed slurry onto aluminum foil to obtain a wet film with a thickness of 120 μm; let the wet film stand for 4 min at 25±2℃ and relative humidity ≤40%; S4. The wet film after standing is cured in sections. The steps of section curing are as follows: the wet film is heated in an oven at 65°C on the side close to the aluminum foil and at 85°C on the side away from the aluminum foil. After 12 hours, the section curing is completed and an integrated positive electrode electrolyte membrane is obtained.

[0098] Example 9 The preparation method of the integrated positive electrode electrolyte membrane provided in this embodiment is the same as that in Embodiment 8, except that step S1 is omitted, and LiNi with a particle size of 5 μm is directly applied. 0.8 Co 0.1 Mn 0.1 O2 (NCM811) positive electrode active material and polymer electrolyte precursor slurry are mixed.

[0099] Comparative Example 1 The preparation method of the integrated positive electrode electrolyte membrane provided in this comparative example is the same as that in Example 1, except that in step S4, the heating temperature on both sides of the wet membrane is 75°C.

[0100] Comparative Example 2 The preparation method of the integrated positive electrode electrolyte membrane provided in this comparative example is the same as that in Example 1, except that the standing time in step S3 is 1 min.

[0101] Comparative Example 3 The method for preparing the integrated positive electrode electrolyte membrane provided in this comparative example includes the following steps: S1, LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) positive electrode active material, conductive agent (Super P) and binder (PVDF) are mixed in a mass ratio of 8:1:1, NMP solvent is added, and after mixing, a positive electrode slurry is obtained; the positive electrode slurry is coated on aluminum foil, and after drying and rolling, a positive electrode sheet is obtained; S2. The polymer electrolyte precursor slurry of Example 1 is coated onto a release film and cured at 75°C for 8 hours to obtain a polymer electrolyte film. S3. The positive electrode sheet and the polymer electrolyte membrane are hot-pressed at 5MPa and 75℃ to obtain an integrated positive electrode electrolyte membrane.

[0102] Test case Batteries were assembled using the integrated positive electrode electrolyte membranes of Examples 1-9 and Comparative Examples 1-3, respectively; wherein, the integrated positive electrode electrolyte membrane and the graphite negative electrode sheet were assembled into a solid-state battery; the integrated negative electrode electrolyte membrane and the ternary NCM positive electrode sheet were assembled into a solid-state battery; the performance of each solid-state battery was tested, and the results are shown in Table 1.

[0103] The solid-state battery assembly environment was an argon glove box (water and oxygen content <0.1ppm), and the battery assembly pressure was 5MPa. After one cycle of constant current charge-discharge at 0.1C within a voltage range of 2.5-4.3V (vs. Li+ / Li), it was cycled 100 times at 0.5C. Electrochemical impedance spectroscopy was performed at frequencies of 0.1-100kHz.

[0104] Table 1

[0105] As can be seen from Table 1, the integrated positive electrode electrolyte membrane of the present invention has a stable longitudinal gradient structure, and the solid-state battery assembled with it has low interface impedance and excellent cycle performance. The solid-state battery assembled using the integrated negative electrode electrolyte membrane of the present invention has a stable negative electrode interface, is resistant to volume expansion, and has excellent cycle performance. In Comparative Example 1, the polymer composition of the integrated negative electrode electrolyte membrane is relatively uniform, while the polymer on the positive electrode side has an excessively high degree of polymerization and lacks flexible polymer. After 100 cycles at a 0.5C rate, the interface contact on the positive electrode side deteriorates and the capacity retention rate decreases, indicating that the flexible polymer formed by partitioned solidification is crucial for maintaining cycle stability. Comparative Example 2 has a shorter settling time, resulting in a more dispersed particle distribution of the positive electrode active material in the integrated positive electrode electrolyte membrane. The positive electrode active material enrichment area on the positive electrode side is thicker (approximately 50%-60% of the thickness), and the gradient transition buffer layer is wider. Consequently, the interfacial impedance increases faster during long-term cycling, leading to a relatively higher interfacial impedance. Comparative Example 3 directly uses the traditional two-step composite process to press and bond the positive electrode sheet and the polymer electrolyte membrane together. The solid-solid interface has poor contact, low capacity retention after 100 cycles, and obvious cracks appear at the interface after cycling.

[0106] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing an integrated electrode electrolyte membrane, characterized in that, Includes the following steps: A mixed slurry is coated onto a substrate to obtain a wet film; the wet film is then allowed to stand; wherein the mixed slurry comprises an electrode material and a polymer electrolyte precursor slurry; The wet film, after being left to stand, is cured in sections to obtain the integrated electrode electrolyte membrane.

2. The method for preparing the integrated electrode electrolyte membrane according to claim 1, characterized in that, The electrode material includes an electrode active material or an electrode active material with a surface pretreatment layer; And / or, the particle size of the electrode material is 1-20 μm.

3. The method for preparing the integrated electrode electrolyte membrane according to claim 2, characterized in that, Includes at least one of the following features (1) to (4); (1) The electrode active material includes a positive electrode active material or a negative electrode active material; (2) The pretreatment layer includes at least one of oxide electrolyte, polymer electrolyte and sulfide solid electrolyte; (3) The thickness of the pretreatment layer is 1-100 nm; (4) The method of surface coating pretreatment layer includes at least one of sol-gel method, atomic layer deposition method, chemical vapor deposition method, in-situ polymerization method, in-situ conversion method and liquid phase deposition method.

4. The method for preparing the integrated electrode electrolyte membrane according to claim 3, characterized in that, When the electrode active material is a positive electrode active material, the pretreatment layer includes at least one of lithium phosphate, lithium aluminate, lithium titanium aluminum phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium titanate, lithium phosphorus sulfur chloride, polyethylene oxide lithium-conducting composite polymer electrolyte and polyaniline polymer electrolyte. And / or, when the electrode active material is a negative electrode active material, the pretreatment layer includes at least one of lithium phosphorus oxynitride, lithium phosphate, lithium lanthanum zirconium titanate, and polyethylene glycol diacrylate-based composite polymer electrolyte.

5. The method for preparing the integrated electrode electrolyte membrane according to claim 1, characterized in that, The polymer electrolyte precursor slurry comprises: a film-forming material, a lithium salt, an initiator, and a solvent; And / or, the mass ratio of the electrode material to the polymer electrolyte precursor slurry is (1-5):

1.

6. The method for preparing the integrated electrode electrolyte membrane according to claim 5, characterized in that, Includes at least one of the following features (1) to (4); (1) The film-forming material includes at least one of polyethylene glycol diacrylate and its derivatives, polyethylene oxide and its derivatives, vinylene carbonate and its derivatives, trimethylolpropane triacrylate and its derivatives, and polyvinylidene fluoride and its derivatives; (2) The content of the film-forming material in the polymer electrolyte precursor slurry is 20wt%-60wt%; (3) The mass of the lithium salt is 5%-30% of the mass of the film-forming material; (4) The mass of the initiator is 0.1%-3% of the mass of the film-forming material.

7. The method for preparing the integrated electrode electrolyte membrane according to claim 1, characterized in that, Includes at least one of the following features (1) to (3); (1) The coating process further includes: prepolymerizing the mixed slurry to adjust the viscosity of the mixed slurry; the prepolymerization temperature is 40-70℃ and the time is 2-10min; the viscosity of the mixed slurry after prepolymerization is 1000-5000cP; (2) The thickness of the wet film is 50-500 μm; (3) The conditions for standing are: temperature 15-40℃, relative humidity ≤40%, and time 1-30min.

8. The method for preparing the integrated electrode electrolyte membrane according to claim 1, characterized in that, The partitioned curing process includes: heating the side of the wet film closest to the substrate at temperature T1, and heating the side furthest from the substrate at temperature T2; 50℃≤T1<70℃, 70℃≤T2≤100℃; And / or, the curing time of the partition is 2-24 hours.

9. An integrated electrode electrolyte membrane, characterized in that, The integrated electrode electrolyte membrane is prepared using the method described in any one of claims 1-8.

10. A battery, characterized in that, Includes the integrated electrode electrolyte membrane as described in claim 9.

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