A solid-state lithium battery cathode-electrolyte integrated film with field-induced ordered orientation and a preparation method thereof

Abstract

The application discloses a kind of solid-state lithium battery positive electrode-electrolyte integrated film of magnetic field induced ordered orientation and preparation method thereof, belong to full solid-state lithium battery technical field.The application with strong magnetic double-doped manganese iron lithium phosphate positive electrode material and two-dimensional solid-state electrolyte as core raw material, through external gradient magnetic field driving magnetic positive electrode particles directional migration to current collector side, simultaneously drive two-dimensional electrolyte nanosheet to form preferred orientation perpendicular to current collector, in situ forming positive electrode-electrolyte continuous gradient integrated film.The application simultaneously solves the industry pain points that full solid-state battery solid-solid interface contact is poor, two-dimensional electrolyte orientation is disordered, interface side reaction is serious, vertical direction room temperature ionic conductivity is greatly improved compared with random stacking structure, interface impedance is reduced compared with traditional laminated structure;Preparation process is highly compatible with existing lithium battery coating production line, suitable for mass production, can be widely used in high energy density full solid-state lithium battery field.

Description

Technical Field

[0001] This invention belongs to the field of solid-state lithium battery preparation technology, specifically relating to a magnetic field-induced ordered orientation solid-state lithium battery cathode-electrolyte integrated film and its preparation method. Background Technology

[0002] With the rapid development of new energy vehicles and large-scale energy storage industries, the safety hazards and energy density bottlenecks of traditional liquid lithium batteries are becoming increasingly prominent. All-solid-state lithium batteries use non-flammable inorganic electrolytes to replace liquid electrolytes, combining the advantages of high safety and high energy density, and have become the mainstream technology route for next-generation power batteries.

[0003] Lithium manganese iron phosphate (LMFP) combines the high safety and long cycle life of lithium iron phosphate with the high operating voltage of lithium manganese phosphate, offering significant cost advantages. It is a key cathode material for high-performance all-solid-state batteries. However, its application still faces three major industry pain points: First, poor solid-solid interface contact. Traditional stacking processes can only achieve physical point contact between the cathode and electrolyte, resulting in high interface porosity, numerous ion channel breakpoints, and interface impedance reaching hundreds of ohms, severely limiting rate performance. Second, disordered orientation of two-dimensional inorganic electrolytes. Ion transport in sulfide and oxide two-dimensional electrolytes exhibits strong anisotropy, with intralayer conductivity reaching tens of times that of interlayer conductivity. Under traditional coating processes, the random stacking of nanosheets results in an effective vertical conductivity of only a fraction of the intrinsic value, failing to fully utilize the material's intrinsic properties. Third, severe interfacial side reactions. The high operating potential of LMFP easily triggers the oxidative decomposition of sulfide electrolytes, and manganese dissolution further accelerates interface degradation, leading to rapid decay of battery cycle capacity.

[0004] To address the directional regulation of electrolyte ion channels, patent application CN121228454A proposes a magnetic field-induced directional ion-conducting electrolyte membrane. This membrane uses a multi-component blended polymer as the matrix and a metal-organic framework (MOF) as the ion transport phase, and is prepared via magnetic field-assisted electrospinning combined with UV crosslinking. However, this approach has clear application limitations and cannot meet the requirements of all-solid-state batteries: First, the system is incompatible; it is essentially a porous polymer membrane that relies on liquid electrolytes for ion conduction, making it only suitable for semi-solid scenarios, completely different from the conductivity mechanism of all-solid-state inorganic sulfide / oxide electrolytes. Second, its function is singular, focusing only on the pore orientation regulation of the pure electrolyte membrane and not addressing the cathode-electrolyte interface construction, thus failing to solve the core pain point of solid-solid interface contact in all-solid-state batteries. Third, its adaptability is insufficient; the polymer matrix has poor high-voltage stability and lacks an interface buffer design, failing to suppress manganese dissolution and interfacial side reactions in LMFPs, making it difficult to match high-voltage LMFP all-solid-state systems.

[0005] In existing technologies, magnetic field manipulation is mostly used for orientation control of single electrode materials or slurry dispersion. No technology has yet combined magnetic cathode materials with two-dimensional electrolytes, utilizing the migration of cathode particles under a magnetic field to simultaneously align the two-dimensional electrolyte and achieve integrated cathode-electrolyte molding. Therefore, developing a magnetic field-induced integrated film fabrication technology that can simultaneously solve the problems of solid-solid interface contact, two-dimensional electrolyte orientation, and interfacial side reactions is of significant practical importance for promoting the industrialization of all-solid-state lithium batteries. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing a solid-state lithium battery cathode-electrolyte integrated film with magnetic field-induced ordered orientation, so as to solve the problems of poor contact at the cathode-electrolyte interface, disordered two-dimensional electrolyte orientation, and high interface impedance in traditional solid-state batteries.

[0007] Another object of the present invention is to provide an integrated cathode-electrolyte membrane for solid-state lithium batteries prepared by the method.

[0008] The objective of this invention can be achieved through the following technical solutions: Firstly, a method for preparing a magnetically induced ordered orientation solid-state lithium battery cathode-electrolyte integrated film, using strongly magnetic double-doped lithium manganese iron phosphate cathode material and two-dimensional solid electrolyte material as core raw materials, is provided. In-situ orientation is induced by an external gradient magnetic field, and the gradient magnetic field drives the magnetic cathode particles to migrate directionally towards the current collector side, simultaneously causing the two-dimensional electrolyte nanosheets to form a preferred orientation perpendicular to the current collector, thus forming a continuous gradient integrated cathode-electrolyte structure in situ. Specifically, the method includes the following steps: (1) Preparation of precursor slurry: The strong magnetic double-doped lithium manganese iron phosphate cathode material, two-dimensional solid electrolyte material, conductive agent and binder are mixed, and solvent is added to prepare a mixed slurry. The precursor slurry is obtained by mixing and degassing. (2) Magnetic field induced coating: Gradient electromagnets are set on the upper and lower sides of the coating equipment to pour the precursor slurry onto the positive electrode foil to form a wet film. The film is placed in the gradient magnetic field until the slurry is dry, and the positive electrode directional migration and two-dimensional electrolyte vertical orientation are completed simultaneously. (3) Post-processing and shaping: The integrated membrane after surface drying is vacuum dried and cold pressed to obtain the positive electrode-electrolyte integrated membrane.

[0009] An external gradient magnetic field generates a spatially non-uniform magnetic induction intensity distribution. Strongly magnetic, dual-doped lithium manganese iron phosphate particles, acting as the magnetic medium, are subjected to volume forces along the magnetic field gradient direction in the gradient field, spontaneously migrating towards the current collector side where the magnetic field strength is higher. This is the driving force behind the entire orientation process, differing from the conventional approach of directly applying a magnetic field to the electrolyte. Secondly, as the magnetic cathode particles migrate in the slurry medium, they transfer momentum to the surrounding two-dimensional solid electrolyte nanosheets through the viscous drag effect of the slurry and the van der Waals interactions between the particles and the two-dimensional nanosheets. Simultaneously, the two-dimensional electrolyte nanosheets themselves possess anisotropic magnetic susceptibility, rotating under the influence of magnetic torque in the magnetic field. The superposition of these two effects causes the two-dimensional electrolyte nanosheets to simultaneously form a preferred orientation perpendicular to the current collector direction. Furthermore, due to the directional migration of the cathode particles towards the current collector side, a spontaneous spatial redistribution of components is completed before the slurry solidifies. A cathode-enriched region forms near the current collector, while the electrolyte component proportion increases on the side farther from the current collector, naturally forming a transition layer with continuously changing components in between. After post-processing and shaping, the whole becomes an integrated membrane with a continuous gradient between the positive electrode and electrolyte without macroscopic interface, eliminating the solid-solid contact interface of the traditional stacking process from the structural source.

[0010] Furthermore, in step (1), the mass ratio of the strongly magnetic double-doped lithium manganese iron phosphate cathode material, the two-dimensional solid electrolyte material, the conductive agent, and the binder is 30:(58-62):(3-6):(3-6); the solid content of the mixed slurry is 48-52%, and the viscosity of the precursor slurry at 25°C is 3500-4500 mPa. The mixing and degassing process employs a dual planetary mixer, with the following steps: premixing at 800-1000 rpm for 5-6 minutes, cycling at 1500 rpm and 2000 rpm for 5 minutes each for 3-4 cycles, and degassing at 2000 rpm for 2-3 minutes. A positive-electrolyte mass ratio of 30:58-62 is the material basis for the gradient structure formation: a positive electrode proportion of approximately 30% ensures the formation of a continuous positive electrode-enriched conductive network after migration, while an electrolyte proportion of 58-62% ensures the formation of a complete and dense pure electrolyte barrier layer on the outer side. Below 58 parts, ion channels are discontinuous; above 62 parts, energy density decreases. Solid content is 48-52%, and viscosity is 3500-4500 mPa. S-matching ensures that the particle migration distance within the magnetic field's duration is exactly the scale required for gradient stratification.

[0011] Further, in step (1), the conductive agent is one or more of Super P, vapor-grown carbon fiber (VGCF), and acetylene black; the binder is one or more of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), styrene-butadiene rubber (SBR), and polyacrylic acid (PAA); and the solvent is N-methylpyrrolidone (NMP) or p-xylene. Super P / VGCF / acetylene black constitute a zero-dimensional to one-dimensional gradient conductive network, filling the gaps between positive electrode particles to construct a continuous electronic pathway. PVDF-HFP combines the oxidation resistance of PVDF with the film-forming flexibility of HFP, making it suitable for high-voltage LMFP systems; SBR and PAA are suitable for aqueous / weakly polar solvent systems, providing better elasticity and interfacial adhesion. NMP is a good solvent for polyvinylidene fluoride, while p-xylene is suitable for sulfide electrolytes (avoiding the reaction between NMP and sulfides). The two solvents correspond to the oxide and sulfide technical routes, respectively.

[0012] Furthermore, in step (2), the magnetic induction intensity of the gradient electromagnet is 2-3T, the magnetic field gradient is 100-150T / m; the wet film thickness is 400-500μm, and the static magnetic field treatment time is 30min; the positive electrode foil is aluminum foil, and the areal loading of the lithium manganese iron phosphate positive electrode material is controlled at 18-22mg / cm³. 2 ; In step (3), the vacuum drying is a gradient temperature vacuum drying at 80℃ for 12 hours; the cold pressing is a room temperature cold pressing at 20MPa for 30 seconds, or a warm isostatic pressing at 40℃ and 100MPa for 30 seconds; the final integrated film thickness is 85-100μm.

[0013] A magnetic flux density of 2-3 T and a gradient of 100-150 T / m are critical parameters for magnetic particle migration: below the lower limit, the magnetization driving force is insufficient to overcome viscous resistance, resulting in a sharp drop in orientation efficiency; above the upper limit, the risk of particle agglomeration increases, and film surface uniformity deteriorates. A wet film thickness of 400-500 μm corresponds to a practical film thickness of 85-100 μm after drying and cold pressing, with controllable shrinkage and no pinhole cracking. Gradient heating at 80℃ and vacuum drying avoid porosity defects caused by rapid solvent evaporation. Cold pressing at 20 MPa or warm isostatic pressing at 100 MPa further densifies the film, eliminating micropores remaining from the orientation process and reducing interfacial impedance.

[0014] Furthermore, the two-dimensional solid-state electrolyte material is any one of LiCdPS sulfide nanosheets, Vr-LLTO composite nanosheets, and LLZO nanosheets. These three electrolytes represent two technical routes: sulfide and oxide. All possess a layered crystal structure that can be exfoliated into two-dimensional nanosheets, and exhibit strong anisotropy in ion transport (intra-layer >> inter-layer), a prerequisite for magnetic field orientation gain. LiCdPS sulfide has the highest intrinsic ionic conductivity, making it suitable for high-rate applications; Vr-LLTO oxide has good chemical stability and high voltage resistance; and LLZO is a classic garnet-type oxide with excellent compatibility with lithium metal. The selection of these three materials covers the mainstream electrolyte systems for all-solid-state batteries.

[0015] Furthermore, the LiCdPS sulfide nanosheets are prepared via a vacancy-induced intercalation-ion exchange-ultrasonic exfoliation process, specifically including the following steps: (1) Raw material pretreatment: Cd powder, red phosphorus and sulfur powder are dried in an environment of 60℃ and vacuum degree ≤0.1MPa for 8-12h to remove adsorbed impurities; (2) Preparation of CdPS crystals: Cd powder: red phosphorus: sulfur powder = 1:(0.9-1.1):(2.7-3.3) are mixed and ground, and vacuum sealed until the vacuum degree is ≤1×10 -3 After Pa, the temperature is increased to 680-700℃ at 5-10℃ / min and calcined for 7 days. After washing and drying, CdPS crystals are obtained. (3) Vacancy-induced intercalation: CdPS crystals were added to a mixed aqueous solution containing KCl, K2CO3 and EDTA, and the mixture was hydrothermally reacted at 100℃ for 2 h. After washing, KCdPS intercalation products were obtained. The concentration of KCl in the mixed aqueous solution was 1-1.1 mol / L, the concentration of K2CO3 was 0.5-0.6 mol / L, the concentration of EDTA was 0.5-0.6 mol / L, and the solid-liquid ratio of CdPS crystals to the mixed aqueous solution was 0.6-0.7 g / mL. (4) Ion exchange: KCdPS product is mixed with 1.9-2.1 mol / L LiCl aqueous solution and hydrothermally reacted at 95-100℃ for 2-2.5 h. After washing, LiCdPS precipitate is obtained. (5) Ultrasonic exfoliation: The LiCdPS precipitate was dispersed into an aqueous dispersion of 4.5-5.5 mg / mL, ultrasonically treated at 210-220 W and 25 °C for 15-20 min, filtered through a 0.22 μm polycarbonate membrane and dried to obtain LiCdPS sulfide nanosheets.

[0016] The first step involves the high-temperature solid-state synthesis of CdPS layered crystals, which possess a van der Waals layered structure; the second step involves K... + Intercalation utilizes EDTA to complex Cd 2+ Generating lattice vacancies lowers the intercalation energy barrier, K+ Entering the interlayer to expand the interlayer spacing; the third step Li + Exchange K + Replace with Li + The process imparts ionic conductivity; finally, ultrasound is used to exfoliate the bulk material into few-layer nanosheets using interlayer shear forces. Compared to direct liquid-phase exfoliation, this process offers higher yield, more complete layers, and precise control over lithium-ion content.

[0017] Furthermore, the Vr-LLTO composite nanosheets are prepared by directional growth using a vermiculite template, specifically including the following steps: (1) Vermiculite nanosheets were filtered to form a layered framework, and then placed in an ethanol solution to swell for 1 hour to increase the interlayer spacing; (2) According to the target product lanthanum lithium titanium oxide Li 3x La 2 / 3-x The stoichiometric ratio of TiO3 is controlled so that the molar ratio of Li, La, and Ti is 3x:(2 / 3). x):1, Weigh out LiNO3 and La(NO3)3 6H2O and tetrabutyl titanate; wherein, x=0.10~0.13, and LiNO3 in excess of 15wt% to compensate for lithium loss during high-temperature sintering, are dissolved in a mixed solution of anhydrous ethanol and acetic acid in a volume ratio of 8:2, and stirred at 45-50℃ to obtain a precursor solution. (3) The precursor solution was impregnated into the vermiculite layered framework by negative pressure filtration, dried at 55-60℃ for 3-4h, heated to 950-1000℃ at 1-5℃ / min and sintered for 2-2.5h. After annealing, Vr-LLTO composite nanosheets were obtained.

[0018] Vermiculite itself possesses a natural layered structure. After swelling with ethanol to expand the interlayer spacing, it acts as a "nanoreactor." An LLTO precursor solution is impregnated into the vermiculite interlayers under negative pressure. During high-temperature sintering, it grows directionally within a two-dimensional confined space. After annealing to remove the vermiculite template, two-dimensional LLTO nanosheets are obtained. The vermiculite template ensures both the layered morphology and prevents particle agglomeration caused by high-temperature sintering. A 15% excess of LiNO3 is used to compensate for high-temperature lithium volatilization, ensuring accurate stoichiometry.

[0019] Furthermore, the strongly magnetic dual-doped lithium manganese iron phosphate cathode material is prepared through a dual-doping modification-in-situ magnetic coating-segmented sintering process, specifically including the following steps: (1) Precursor preparation: Lithium source, manganese source, iron source and phosphorus source are prepared according to the target product lithium manganese iron phosphate LiMn x Fe 1-xThe elemental stoichiometry of PO4 is as follows: the molar ratio of Li, Mn+Fe, and P is (1.0-1.05):1:1, and Mn accounts for 20%-80% of the total molar amount of Mn and Fe. The mixture is prepared into a 0.5-1.5 mol / L aqueous solution, the pH is adjusted to 7-9, and the mixture is stirred at 50-80℃ for 2-4 hours. After filtration and drying, the LMFP precursor is obtained. (2) Dual doping modification: The LMFP precursor is mixed with Li site dopant and Mn / Fe site dopant. The Li site dopant accounts for 0.5%-2% of the precursor mass, and the Mn / Fe site dopant accounts for 0.5%-2% of the precursor mass. The mixture is ball-milled at 300-500 rpm for 4-8 hours to obtain the doped precursor. (3) Magnetic coating granulation: 2%-5% of carbon source and 1%-3% of iron salt by mass of precursor are added to doped precursor, water is added to make slurry, and spray drying is performed to obtain modified powder with in-situ coating of Fe3O4. (4) Pre-calcination to remove template: Mix the modified powder and template agent at a mass ratio of 100:(5-10), and pre-calcine at 300-400℃ for 2-3 hours under an inert atmosphere to remove the template agent and obtain the oriented nanostructure precursor; (5) Segmented sintering activation: The oriented nanostructure precursor is heated to 500-600℃ at 2-5℃ / min and held for 3-5h in an inert atmosphere, then heated to 650-750℃ and held for 6-10h. After cooling and pulverizing, a strongly magnetic double-doped lithium manganese iron phosphate cathode material is obtained.

[0020] Precursor preparation by co-precipitation method ensures atomic-level uniformity of elements; Li-site and Mn / Fe-site dual doping: Mg 2+ / Na + Expand Li + diffusion channels, Nb 5+ / Zr 4+ A stable lattice suppresses Jahn-Teller distortion; spray drying in situ coating of Fe3O4 and carbon layers, with Fe3O4 providing magnetic response and the carbon layer constructing an electronic conductive network and isolating interfacial side reactions; pre-sintering with a template agent creates pores to form directional nanochannels; segmented sintering: low-temperature pre-sintering completes primary crystallization, and high-temperature sintering promotes crystal growth and carbon coating, avoiding abnormal grain growth caused by one-step high-temperature sintering.

[0021] Furthermore, the Li site dopant is Mg. 2+ Na + One or more of the corresponding compounds; the Mn / Fe site dopant is Nb. 5+ Zr 4+ Ti 4+One or more of the corresponding compounds; the carbon source is one or more of glucose, sucrose, and citric acid; the iron salt is one or more of ferric nitrate and ferrous acetate; the template agent is one or more of P123 and F127; the inlet air temperature of the spray drying is 200-230℃, and the outlet air temperature is 90-110℃. Mg is selected as the Li-site dopant. 2+ Na + Because its ionic radius is similar to that of Li + The proximity of Li sites to the olivine lattice facilitates lattice expansion, broadening the Li content. + Migration pathway. Mn / Fe site selection Nb 5+ Zr 4+ Ti 4+ High-valence transition metals can introduce vacancies or stabilize Mn through charge compensation effects. 3+ Valence state, inhibiting Jahn-Teller distortion and manganese dissolution. Glucose / sucrose / citric acid as carbon source, forming a uniform amorphous carbon coating layer after pyrolysis. Ferric nitrate / ferrous acetate as iron source, generating Fe3O4 magnetic phase in situ through thermal decomposition under an inert atmosphere. P123 / F127 block copolymer as soft template, leaving a mesoporous structure after low-temperature decomposition.

[0022] Secondly, the present invention also provides a magnetically induced ordered orientation solid-state lithium battery cathode-electrolyte integrated film, which is prepared by any of the above preparation methods; the integrated film forms a continuous gradient structure from the cathode foil side outward of a cathode enrichment layer, a component transition layer and a pure electrolyte layer, without macroscopic interfaces; the two-dimensional solid electrolyte nanosheets are preferentially oriented perpendicular to the cathode foil.

[0023] The beneficial effects of this invention are: (1) This invention breaks through the existing single control approach of directly applying a magnetic field to the electrolyte. It uses magnetic LMFP particles as the orientation driving force carrier. In the gradient magnetic field, the particles are driven by magnetization to migrate directionally towards the positive electrode foil. With the precise optimization of the slurry viscosity window, it ensures that the particles have sufficient migration freedom and avoids component sedimentation and stratification. Through the viscous drag effect of the slurry and the van der Waals forces between the layers, the two-dimensional electrolyte nanosheets are simultaneously driven to rotate to a preferred orientation perpendicular to the current collector. Stable orientation can be completed within 30 minutes. This synergistic mechanism makes the high conductivity ion channels in the two-dimensional electrolyte layer completely aligned with the charging and discharging direction of the battery. The room temperature ion conductivity in the vertical direction is significantly improved compared with the random stacking structure, which fully releases the intrinsic transport performance of the two-dimensional electrolyte material.

[0024] (2) This invention abandons the traditional assembly process of separately preparing the positive electrode sheet and electrolyte membrane and stacking and cold pressing them. Instead, it adopts an integrated scheme of in-situ solidification of the positive electrode-electrolyte blend slurry, which can naturally form a continuous gradient structure of "positive electrode enrichment layer on the current collector side - intermediate transition layer - outer pure electrolyte layer". There are no macroscopic interfaces and physical contact pores, which increases the effective contact area of ​​the interface. Combined with cold pressing densification treatment, the interface impedance is significantly reduced compared with the traditional stacked structure. At the same time, the vertically oriented electrolyte sheet forms end face contact with the positive electrode particles, further shortening the interface charge transfer path and realizing the seamless continuous connection of the ion transport channel.

[0025] (3) The Fe3O4 magnetic coating layer on the surface of LMFP simultaneously serves as a magnetic field response carrier, an electronic conductive network, and an interface buffer layer. It provides magnetization driving force for magnetic field orientation and isolates the LMFP active material from direct contact with the sulfide electrolyte, suppressing the side reactions of electrolyte oxidation decomposition and manganese dissolution at high potentials. Combined with the integrated gradient transition structure, it can buffer the volume stress of lithium insertion / extraction at the positive electrode during charging and discharging, and avoid interface peeling failure during cycling.

[0026] (4) The integrated film forming process of the present invention is highly compatible with the existing lithium battery coating production line. Only a gradient electromagnet module needs to be added to the coating and drying section, without large-scale equipment modification. All process parameters are set with reasonable fault tolerance windows. The matching design of solid content, viscosity and wet film thickness ensures that the drying shrinkage rate is controllable. The film surface is free of defects such as pinholes and cracks. The batch performance fluctuation is small, which is suitable for large-scale industrial production. Attached Figure Description

[0027] The invention will now be further described with reference to the accompanying drawings.

[0028] Figure 1 This is a photograph of the integrated positive electrode-electrolyte membrane prepared in Example 1 of the present invention. Figure 2 This is a SEM image of the integrated positive electrode-electrolyte membrane prepared in Example 1 of the present invention; Figure 3 This is a comparison diagram of the in-plane (left) and out-of-plane (right) conductivity of the integrated positive electrode-electrolyte membrane prepared in Example 1 of the present invention; Figure 4 This is a comparison chart showing the capacity retention of the integrated positive electrode-electrolyte membranes prepared in Examples 1 and 4 and Comparative Example 1 of the present invention. Detailed Implementation

[0029] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0030] General experimental conditions: 1. Main raw materials and reagents Metallic Cd powder (99.5% purity), red phosphorus (99.99% purity), sulfur powder (99.5% purity), potassium chloride (KCl, analytical grade), potassium carbonate (K2CO3, analytical grade), ethylenediaminetetraacetic acid (EDTA, analytical grade), and lithium chloride (LiCl, analytical grade) were all purchased from Sinopharm Chemical Reagent Co., Ltd.; vermiculite nanosheets (1-5 μm in diameter), lithium nitrate (LiNO3, battery grade), and lanthanum nitrate hexahydrate (La(NO3)3) were also purchased. 6H2O (analytical grade), tetrabutyl titanate (Ti(OC4H9)4, analytical grade), tantalum-doped lanthanum zirconium oxide (LLZO) bulk powder; lithium carbonate (Li2CO3, battery grade), manganese sulfate (MnSO4) H2O (battery grade), ferrous sulfate (FeSO4) 7H2O (battery grade), ammonium dihydrogen phosphate (NH4H2PO4 (battery grade), magnesium oxide (MgO, analytical grade), niobium pentoxide (Nb2O5, analytical grade), glucose (analytical grade), ferric nitrate nonahydrate (Fe(NO3)3) 9H2O (analytical grade), P123 block copolymer (analytical grade); conductive agent SuperP, vapor-grown carbon fiber (VGCF), acetylene black; binder polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), styrene-butadiene rubber (SBR); solvent N-methylpyrrolidone (NMP), p-xylene, all battery grade; commercial Li6PS5Cl electrolyte (room temperature ionic conductivity 1.0 mS). cm -1 Battery grade); aluminum foil current collector (12μm thick), lithium indium alloy anode (100μm thick).

[0031] 2. Characterization and Testing Methods (1) Microstructure characterization: The crystal structure was analyzed by X-ray diffraction (XRD), the cross-sectional morphology and elemental distribution were observed by scanning electron microscopy (SEM), and the thickness of the two-dimensional nanosheets was tested by atomic force microscopy (AFM). (2) Ionic conductivity test: Electrochemical impedance spectroscopy (EIS) was performed using an electrochemical workstation with a frequency range of 1 Hz to 1 MHz, an AC amplitude of 10 mV, and a test temperature of 25 ℃. The conductivity was determined using the formula σ = L / (R). S) Calculate the vertical ionic conductivity, where L is the electrolyte membrane thickness, R is the bulk impedance, and S is the effective contact area; (3) Interface impedance test: The integrated membrane and lithium indium alloy are assembled into a symmetrical battery. The total impedance of the EIS test is the total impedance of the positive electrode-electrolyte interface after deducting the body impedance. The test temperature is 25℃. (4) Electrochemical performance test: The integrated membrane and lithium indium alloy negative electrode were assembled into a CR2032 mold battery and constant current charge and discharge test was performed in a constant temperature chamber at 25℃ with a voltage range of 2.5~4.2V; the first discharge specific capacity was tested at 0.1C rate, and the capacity retention rate was calculated after 500 cycles at 5C rate.

[0032] Example 1 (1) Preparation of oriented LiCdPS two-dimensional nanosheets ① Raw material pretreatment: Weigh out metal Cd powder, red phosphorus and sulfur powder respectively, and accurately weigh them according to the molar ratio Cd:P:S=1:1:3. Place them in a vacuum drying oven and statically dry them for 10 hours at 60℃ and vacuum degree ≤0.1MPa to completely remove the moisture and volatile impurities adsorbed on the surface of the raw materials.

[0033] ②CdPS crystal preparation: The three pretreated raw materials were added to an agate mortar and ground for 20 minutes until uniformly mixed. The mixture was then transferred to a quartz ampoule and evacuated to 8×10⁻⁶. -4 After Pa, the mixture was sealed; it was placed in a tube furnace and heated to 700℃ at 5℃ / min, and calcined at a constant temperature for 7 days. After natural cooling, it was ultrasonically washed three times with anhydrous ethanol and vacuum dried at 60℃ for 12 hours to obtain CdPS layered crystals.

[0034] ③Vacation-induced intercalation: Prepare a mixed aqueous solution containing 1 mol / L KCl, 0.5 mol / L K2CO3, and 0.5 mol / L EDTA. Add CdPS crystals at a solid-liquid ratio of 0.65 g / mL. After ultrasonic dispersion for 10 min, transfer to a high-pressure reactor and hydrothermally react at 100℃ for 2 h. The product is washed three times by centrifugation with deionized water to obtain the KCdPS intercalation product.

[0035] ④ Ion exchange: The KCdPS product was dispersed in a 2 mol / L LiCl aqueous solution with a solid-liquid ratio of 0.5 g / mL. The lithium ion exchange was completed by hydrothermal reaction at 100℃ for 2 h. The product was washed three times each with deionized water and anhydrous ethanol to remove residual salts and obtain LiCdPS precipitate.

[0036] ⑤ Ultrasonic exfoliation: The LiCdPS precipitate was prepared into an aqueous dispersion of 5 mg / mL and placed in an ice-water bath. It was then ultrasonically treated at 25℃ for 15 min using a 220W probe ultrasonic instrument. After ultrasonication, the mixture was vacuum filtered through a 0.22 μm polycarbonate membrane. The filter cake was then vacuum dried at 60℃ for 8 h to obtain few-layer LiCdPS two-dimensional nanosheets. The average thickness was approximately 4.2 nm and the sheet diameter was 1-3 μm, as determined by AFM.

[0037] (2) Preparation of strongly magnetic double-doped LMFP cathode material ① Precursor preparation: according to the target product lithium manganese iron phosphate LiMn 0.4 Fe 0.6The elemental stoichiometry of PO4 was used, with a 5% excess of lithium source to compensate for losses during high-temperature sintering. The final molar ratio of Li, Mn+Fe, and P was 1.05:1:1, with Mn accounting for 40% of the total molar amount of Mn and Fe. A mixed aqueous solution with a total cation concentration of 1 mol / L was prepared, and ammonia was added dropwise under stirring to adjust the pH to 8.0. The temperature was raised to 65℃ and stirred for 3 hours. After the reaction was completed, the mixture was filtered while hot, and the filter cake was washed, dried at 110℃ for 18 hours, and ground to obtain the LMFP precursor.

[0038] ②Dual doping modification: Take 100g of LMFP precursor, add 1wt% MgO (Li site dopant) and 1wt% Nb2O5 (Mn / Fe site dopant), add zirconia balls at a ball-to-material ratio of 20:1, and ball mill at 400rpm for 6h to obtain a uniformly doped precursor.

[0039] ③ Magnetic coating granulation: 3wt% glucose (carbon source) and 2wt% ferric nitrate nonahydrate (iron source) are added to the doped precursor, and deionized water is added to prepare a slurry with a solid content of 30%. After stirring evenly, the slurry is spray-dried at an inlet air temperature of 220℃ and an outlet air temperature of 100℃ to obtain spherical modified powder with in-situ coating of iron source and carbon source.

[0040] ④ Pre-calcination and template removal: Take 100g of modified powder, add 7wt% P123 block copolymer (template agent) and mix evenly. Under a high-purity argon atmosphere, heat to 350℃ at 2℃ / min and pre-calcine at a constant temperature for 2.5h to decompose and remove the template agent, thus obtaining the oriented nanostructure precursor.

[0041] ⑤ Segmented sintering activation: Continue to heat to 550℃ at 3℃ / min under a high-purity argon atmosphere and hold for 4h to complete primary crystallization, then heat to 700℃ and sinter at a constant temperature for 8h to complete crystal growth and carbon coating; after natural cooling, airflow pulverize to D50=2-3μm to obtain a strongly magnetic double-doped LMFP cathode material with a saturation magnetization of 8.2 emu / g.

[0042] (3) Preparation of magnetic field-induced integrated cathode-electrolyte membrane ① Precursor slurry preparation: Weigh the solid raw materials according to the mass ratio of strong magnetic LMFP:LiCdPS nanosheets:SuperP:PVDF-HFP = 30:58:3:3, and prepare a mixed slurry with a solid content of 50% using NMP as solvent. Mix and degas using a dual planetary mixer: premix at 800 rpm for 5 min, cycle three times at 1500 rpm and 2000 rpm for 5 min each, and then degas under vacuum at 2000 rpm for 2 min. The slurry viscosity was measured to be 4020 mPa at 25℃ using a rotational viscometer. s.

[0043] ② Magnetic field induced coating molding: Gradient electromagnets are installed on the upper and lower sides of the coating equipment, with the magnetic field direction perpendicular to the current collector plane. The magnetic induction intensity is set to 2.5T and the magnetic field gradient is 120T / m. The precursor slurry is poured onto a 12μm thick aluminum foil, and the wet film thickness is controlled to be 450μm. The magnetic field is kept in a static environment of 25℃ and ≤20% humidity for 30 minutes until the slurry is surface dry, and the directional migration of positive electrode particles and the vertical orientation of two-dimensional electrolyte are completed simultaneously.

[0044] ③ Post-processing and shaping: The surface-dried integrated membrane was subjected to gradient temperature vacuum drying: the temperature was increased from room temperature to 60℃ at 2℃ / min and held for 2 hours, then increased to 80℃ and held for 10 hours, for a total drying time of 12 hours; after drying, it was cold-pressed at 20MPa on a plate at room temperature for 30 seconds to obtain a positive electrode-electrolyte integrated membrane with a thickness of 92μm and an LMFP active material surface loading of 20mg / cm³. 2 .

[0045] ④ Battery assembly is performed under the same general experimental conditions.

[0046] A physical image of the prepared positive electrode-electrolyte integrated membrane is shown below. Figure 1 As shown; its SEM image is as follows. Figure 2 As shown; a comparison of the in-plane (left) and out-of-plane (right) conductivity of the integrated positive electrode-electrolyte membrane. Figure 3 As shown, this invention achieves high conductivity of the integrated positive electrode-electrolyte membrane by magnetically inducing the longitudinal alignment of the electrolyte.

[0047] Example 2 The only difference between this embodiment and Embodiment 1 is that: 1. Preparation of precursor slurry: The solid-phase mass ratio is adjusted to LMFP:LiCdPS:SuperP:PVDF-HFP=30:62:6:6; 2. The process of the dual planetary mixer is adjusted as follows: premix at 1000 rpm for 6 minutes, cycle at 1500 rpm and 2000 rpm for 5 minutes each for 4 times, and degas at 2000 rpm for 3 minutes. 3. Adjust the wet membrane thickness to 480 μm, resulting in a final integrated membrane thickness of 96 μm and an LMFP areal loading of 20 mg / cm³. 2 .

[0048] The preparation of other raw materials, magnetic field parameters, and post-processing techniques are completely consistent with those in Example 1.

[0049] Example 3 The only difference between this embodiment and Embodiment 1 is that the gradient electromagnet parameters are adjusted to a magnetic induction intensity of 2T and a magnetic field gradient of 100T / m; the remaining raw material preparation, slurry ratio, and post-processing are completely consistent with Embodiment 1, resulting in a final integrated membrane thickness of 91μm and an LMFP areal loading of 20mg / cm².2 .

[0050] Example 4 The only difference between this embodiment and Embodiment 1 is that the gradient electromagnet parameters are adjusted to a magnetic induction intensity of 3T and a magnetic field gradient of 150T / m; the remaining raw material preparation, slurry ratio, and post-processing are completely consistent with Embodiment 1, resulting in a final integrated membrane thickness of 93μm and an LMFP areal loading of 20mg / cm². 2 .

[0051] Example 5 The difference between this embodiment and Embodiment 1 is that: 1. The two-dimensional electrolyte was replaced with Vr-LLTO composite nanosheets. The preparation process was as follows: vermiculite nanosheets were filtered to form a layered framework, and swollen in ethanol for 1 hour; according to the target product, lanthanum lithium titanium oxide (Li) 3x La 2 / 3-x The stoichiometric ratio of TiO3 (x = 0.10~0.13) is controlled so that the molar ratio of Li, La, and Ti is 3x:(2 / 3). x):1, Weigh out LiNO3 and La(NO3)3 6H2O and tetrabutyl titanate; with an additional 15wt% LiNO3 to compensate for lithium loss during high-temperature sintering, an ethanol-acetic acid precursor solution was prepared and stirred evenly at 50℃; after impregnation under negative pressure, it was dried at 60℃ for 3h, heated to 1000℃ at 1℃ / min for 2h, and annealed to obtain Vr-LLTO nanosheets.

[0052] 2. The LMFP load capacity was adjusted to 22 mg / cm². 2 The corresponding wet film thickness is 480 μm; The remaining slurry ratios, magnetic field parameters, and post-processing were consistent with those in Example 1, and the final integrated membrane thickness was 95 μm.

[0053] Example 6 The difference between this embodiment and Embodiment 1 is that: 1. The two-dimensional electrolyte was replaced with LLZO two-dimensional nanosheets, which were prepared by intercalation-liquid phase exfoliation method; 2. The binder used is SBR, and the solvent used is p-xylene; 3. Post-treatment involves isostatic pressing at 40℃ and 100MPa for 30 seconds; 4. The LMFP surface loading is adjusted to 18 mg / cm². 2 The corresponding wet film thickness is 420 μm; The final integrated membrane thickness is 87μm.

[0054] Example 7 The only difference between this embodiment and Embodiment 1 is that: 1. Precursor slurry preparation: The conductive agent is a mixture of acetylene black and VGCF at a mass ratio of 1:1, with a total addition of 4.5 parts; the binder is SBR, with an addition of 4.5 parts; the solvent is replaced with p-xylene; the solid phase mass ratio is LMFP:LiCdPS:mixed conductive agent:SBR=30:61:4.5:4.5, and the total solid content is maintained at 50%; 2. The process of the dual planetary mixer was adjusted as follows: premix at 900 rpm for 5.5 min, cycle at 1500 rpm and 2000 rpm for 5 min each for 3 times, and degas at 2000 rpm for 2.5 min. The final slurry viscosity at 25℃ was 3870 mPa. s; The remaining LiCdPS preparation, LMFP preparation, magnetic field parameters, and cold pressing process were completely consistent with those in Example 1. The final integrated film thickness was 93 μm, and the LMFP areal loading was 20 mg / cm³. 2 .

[0055] Example 8 The only difference between this embodiment and Embodiment 1 is the preparation of the strongly magnetic LMFP cathode material: 1. Dual-doping modification: The Li site dopant is replaced with Na2CO3 (Na + Doping, accounting for 1.2 wt% of the precursor mass), the Mn / Fe site dopant was replaced with ZrO2 (Zr 4+ Doping, accounting for 0.8 wt% of the precursor mass); 2. Magnetic coating granulation: The carbon source is replaced with sucrose (3.5 wt%), and the iron salt is replaced with ferrous acetate (1.5 wt%). 3. Pre-calcination and template removal: The template agent is replaced with F127, with an addition amount of 8 wt%; The remaining LMFP precursor preparation, sintering process, electrolyte preparation, and integrated film formation process were completely consistent with those in Example 1. The final integrated film thickness was 91 μm, and the LMFP areal loading was 20 mg / cm³. 2 .

[0056] Comparative Example 1 The only difference between this comparative example and Example 1 is that the gradient magnetic field is not activated during the coating process, and the slurry is allowed to flow and dry naturally; all other process parameters are completely identical.

[0057] The comparison graphs of capacity retention rates of the integrated cathode-electrolyte membranes prepared in Examples 1 and 4 and Comparative Example 1 are shown in the figure. Figure 4 As shown.

[0058] Comparative Example 2 The only difference between this comparative example and Example 1 is that the solid phase mass ratio is adjusted to LMFP:LiCdPS:SuperP:PVDF-HFP=30:55:2:3, while the other process parameters are completely the same.

[0059] Comparative Example 3 The only difference between this comparative example and Example 1 is that the gradient electromagnet has a magnetic induction intensity of 1T and a magnetic field gradient of 50T / m, while the other process parameters are completely identical.

[0060] Comparative Example 4 The only difference between this comparative example and Example 1 is that no iron salt is added during the preparation of LMFP; only carbon coating is performed, and there is no Fe3O4 magnetic layer. The magnetic field, slurry, and integrated process are completely the same.

[0061] Comparative Example 5 The only difference between this comparative example and Example 1 is that: 1. The cathode material is non-magnetic pure carbon coated LMFP (same as comparative example 4); 2. Nano Fe3O4 particles, accounting for 2 wt% of the electrolyte mass, were added to the slurry as a magnetic field response medium, while the remaining solid phase ratio and total solid content were the same as in Example 1; 3. The magnetic field-induced coating process parameters are completely consistent with those in Example 1, relying on free Fe3O4 particles to drive the electrolyte orientation; The remaining processes are the same as in Example 1, with a final integrated membrane thickness of 94 μm and an LMFP areal loading of 20 mg / cm³. 2 .

[0062] Comparative Example 6 The only difference between this comparative example and Example 1 is that: 1. Preparation of Oriented Positive Electrode Sheets: A slurry was prepared by mixing a strongly magnetic LMFP, a conductive agent, and a binder in an 8:1:1 ratio. The slurry was then coated under the same magnetic field parameters to prepare an oriented positive electrode sheet. After drying and cold pressing, the sheet reached a thickness of 40 μm and had an LMFP areal loading of 20 mg / cm². 2 ; 2. Preparation of oriented electrolyte membrane: LiCdPS, binder and conductive agent were mixed in a ratio of 90:5:5 to form a slurry. 2wt% Fe3O4 was added to assist in magnetic field orientation. An oriented electrolyte membrane was prepared under the same magnetic field parameters. After drying and cold pressing, the thickness was 55μm. 3. Stacking assembly: Align and stack the oriented positive electrode sheet and the oriented electrolyte membrane, and cold press at 30MPa for 60s to obtain a stacked structure with a total thickness of 95μm; The remaining battery assembly conditions are the same as in Example 1.

[0063] Performance Test Results and Analysis Table 1

[0064] As can be seen from Table 1, the vertical ionic conductivity of all examples 1-8 is ≥0.74 mS. cm -1 Interface impedance ≤17.9Ω cm 2 The 5C cycle capacity retention rate is ≥90%, and the performance is stable and at an excellent level, proving that the parameter range and raw material selection scheme of the present invention have sufficient feasibility and process tolerance.

[0065] Compared to Example 1, without magnetic field induction, the two-dimensional electrolytes in Comparative Example 1 exhibit random stacking, with vertical ionic conductivity only 25% of that in the oriented state, interfacial impedance increasing by 92%, and significant degradation in rate capability and cycling performance. The principle behind this is that a gradient magnetic field drives the directional migration of magnetic LMFP particles, which, through viscous dragging, cause the two-dimensional electrolyte sheets to align vertically, aligning the high-conductivity ion channels within the layer with the charging and discharging directions, fundamentally reducing ion transport resistance.

[0066] Compared to Example 1, in Comparative Example 2, when the electrolyte content was below 58 parts, the continuous ion transport channels in the slurry were disrupted, the interfacial impedance increased significantly, and the cycle stability decreased. The principle is that an electrolyte content of 58-62 parts ensures that the cathode particles are fully coated with electrolyte, while forming a continuous oriented electrolyte layer; too low a ratio will prevent the construction of a complete ion network, while too high a ratio will reduce the proportion of positive electrode active material and affect the energy density.

[0067] Compared with Example 1, in Comparative Example 3, when the magnetic field strength and gradient are too low, the magnetization driving force on the magnetic LMFP particles is insufficient to overcome the viscous resistance of the slurry, resulting in a significant reduction in directional migration and orientation effects, and a substantial decrease in ionic conductivity. The principle is that the magnetic field driving force is positively correlated with the magnetic field gradient. A gradient range of 100-150 T / m can ensure sufficient migration of magnetic particles in the slurry while avoiding particle agglomeration caused by excessively high magnetic fields.

[0068] Compared with Example 1, the interface impedance of the traditional non-oriented stacked structure in Comparative Example 6 is several times that of the integrated structure, and the cycle capacity retention rate is reduced. This is because the in-situ integrated molding eliminates the macroscopic interface between the positive electrode and the electrolyte, forming a continuous gradient structure, and the ion channels are connected without any breaks at the interface, which solves the problems of poor solid-solid contact and high interface impedance in the traditional stacking process.

[0069] Compared with Example 1, Comparative Examples 4 and 5 show that the non-magnetically coated LMFP cannot respond to magnetic field migration and cannot drive electrolyte orientation, resulting in performance close to that of the non-magnetic sample. In contrast, the conventional orientation scheme with added magnetic particles to the electrolyte has a weaker orientation effect than the magnetic positive electrode carrier, and the additional introduced free magnetic particles will disrupt ion transport channels and increase interfacial side reaction sites, resulting in performance that is still significantly lower than that of the present invention.

[0070] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for preparing a magnetically induced ordered orientation solid-state lithium battery cathode-electrolyte integrated film, characterized in that, Specifically, the following steps are included: (1) Mix the strong magnetic double-doped lithium manganese iron phosphate cathode material, two-dimensional solid electrolyte material, conductive agent and binder, add solvent to prepare a mixed slurry, and obtain the precursor slurry by mixing and degassing; (2) Set gradient electromagnets on the upper and lower sides of the coating equipment, pour the precursor slurry onto the positive electrode foil to form a wet film, and let it stand in the gradient magnetic field until the slurry is dry, so as to simultaneously complete the positive electrode directional migration and the two-dimensional electrolyte vertical orientation. (3) The integrated membrane after surface drying is vacuum dried and cold pressed to obtain the positive electrode-electrolyte integrated membrane.

2. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 1, characterized in that, In step (1), the mass ratio of the strongly magnetic double-doped lithium manganese iron phosphate cathode material, the two-dimensional solid electrolyte material, the conductive agent, and the binder is 30:(58-62):(3-6):(3-6); the solid content of the mixed slurry is 48-52%, and the viscosity of the precursor slurry at 25°C is 3500-4500 mPa. The mixing and degassing process is carried out using a dual planetary mixer, with the following steps: premixing at 800-1000 rpm for 5-6 minutes, cycling at 1500 rpm and 2000 rpm for 5 minutes each for 3-4 times, and degassing at 2000 rpm for 2-3 minutes.

3. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 1, characterized in that, In step (1), the conductive agent is one or more of SuperP, vapor-grown carbon fiber, and acetylene black; the binder is one or more of polyvinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene rubber, and polyacrylic acid; and the solvent is N-methylpyrrolidone or p-xylene.

4. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 1, characterized in that, In step (2), the magnetic induction intensity of the gradient electromagnet is 2-3T, the magnetic field gradient is 100-150T / m; the wet film thickness is 400-500μm, and the static magnetic field treatment time is 30min; the positive electrode foil is aluminum foil, and the areal loading of the lithium manganese iron phosphate positive electrode material is controlled at 18-22mg / cm³. 2 ; In step (3), the vacuum drying is a gradient temperature vacuum drying at 80℃ for 12 hours; the cold pressing is a room temperature cold pressing at 20MPa for 30 seconds, or a warm isostatic pressing at 40℃ and 100MPa for 30 seconds; the final integrated film thickness is 85-100μm.

5. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 1, characterized in that, The two-dimensional solid electrolyte material is any one of LiCdPS sulfide nanosheets, Vr-LLTO composite nanosheets, and LLZO nanosheets.

6. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 5, characterized in that, The LiCdPS sulfide nanosheets were prepared by a vacancy-induced intercalation-ion exchange-ultrasonic exfoliation process, specifically including the following steps: (1) Raw material pretreatment: Cd powder, red phosphorus and sulfur powder are dried in an environment of 60℃ and vacuum degree ≤0.1MPa for 8-12h to remove adsorbed impurities; (2) Preparation of CdPS crystals: Cd powder: red phosphorus: sulfur powder = 1:(0.9-1.1):(2.7-3.3) are mixed and ground, and vacuum sealed until the vacuum degree is ≤1×10 -3 After Pa, the temperature is increased to 680-700℃ at 5-10℃ / min and calcined for 7 days. After washing and drying, CdPS crystals are obtained. (3) Vacancy-induced intercalation: CdPS crystals were added to a mixed aqueous solution containing KCl, K2CO3 and EDTA, and the mixture was hydrothermally reacted at 100℃ for 2 h. After washing, KCdPS intercalation products were obtained. The concentration of KCl in the mixed aqueous solution was 1-1.1 mol / L, the concentration of K2CO3 was 0.5-0.6 mol / L, the concentration of EDTA was 0.5-0.6 mol / L, and the solid-liquid ratio of CdPS crystals to the mixed aqueous solution was 0.6-0.7 g / mL. (4) Ion exchange: KCdPS product is mixed with 1.9-2.1 mol / L LiCl aqueous solution and hydrothermally reacted at 95-100℃ for 2-2.5 h. After washing, LiCdPS precipitate is obtained. (5) Ultrasonic exfoliation: The LiCdPS precipitate was dispersed into an aqueous dispersion of 4.5-5.5 mg / mL, ultrasonically treated at 210-220 W and 25 °C for 15-20 min, filtered through a 0.22 μm polycarbonate membrane and dried to obtain LiCdPS sulfide nanosheets.

7. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 5, characterized in that, The Vr-LLTO composite nanosheets are prepared by directional growth using a vermiculite template, specifically including the following steps: (1) Vermiculite nanosheets were filtered to form a layered framework, and then placed in an ethanol solution to swell for 1 hour to increase the interlayer spacing; (2) According to the target product lanthanum lithium titanium oxide Li 3x La 2 / 3-x The stoichiometric ratio of TiO3 is controlled so that the molar ratio of Li, La, and Ti is 3x:(2 / 3). x):1, Weigh out LiNO3 and La(NO3)3 6H2O and tetrabutyl titanate; wherein, x=0.10~0.13, and LiNO3 in excess of 15wt% to compensate for lithium loss during high-temperature sintering, are dissolved in a mixed solution of anhydrous ethanol and acetic acid in a volume ratio of 8:2, and stirred at 45-50℃ to obtain a precursor solution. (3) The precursor solution was impregnated into the vermiculite layered framework by negative pressure filtration, dried at 55-60℃ for 3-4h, heated to 950-1000℃ at 1-5℃ / min and sintered for 2-2.5h. After annealing, Vr-LLTO composite nanosheets were obtained.

8. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 1, characterized in that, The strongly magnetic, dual-doped lithium manganese iron phosphate cathode material is prepared through a dual-doping modification-in-situ magnetic coating-segmented sintering process, specifically including the following steps: (1) Precursor preparation: Lithium source, manganese source, iron source and phosphorus source are prepared according to the target product lithium manganese iron phosphate LiMn x Fe 1-x The elemental stoichiometry of PO4 is as follows: the molar ratio of Li, Mn+Fe, and P is (1.0-1.05):1:1, and Mn accounts for 20%-80% of the total molar amount of Mn and Fe. The mixture is prepared into a 0.5-1.5 mol / L aqueous solution, the pH is adjusted to 7-9, and the mixture is stirred at 50-80℃ for 2-4 hours. After filtration and drying, the LMFP precursor is obtained. (2) Dual doping modification: The LMFP precursor is mixed with Li site dopant and Mn / Fe site dopant. The Li site dopant accounts for 0.5%-2% of the precursor mass, and the Mn / Fe site dopant accounts for 0.5%-2% of the precursor mass. The mixture is ball-milled at 300-500 rpm for 4-8 hours to obtain the doped precursor. (3) Magnetic coating granulation: 2%-5% of carbon source and 1%-3% of iron salt by mass of the precursor are added to the doped precursor, water is added to make a slurry, and spray drying is performed to obtain modified powder with in-situ coating of Fe3O4. (4) Pre-calcination to remove template: Mix the modified powder and template agent at a mass ratio of 100:(5-10), and pre-calcine at 300-400℃ for 2-3 hours under an inert atmosphere to remove the template agent and obtain the oriented nanostructure precursor; (5) Segmented sintering activation: The oriented nanostructure precursor is heated to 500-600℃ at 2-5℃ / min and held for 3-5h in an inert atmosphere, then heated to 650-750℃ and held for 6-10h. After cooling and pulverizing, a strongly magnetic double-doped lithium manganese iron phosphate cathode material is obtained.

9. The method for preparing a magnetically induced ordered oriented solid-state lithium battery cathode-electrolyte integrated film according to claim 8, characterized in that, The Li site dopant is Mg. 2+ Na + One or more of the corresponding compounds; the Mn / Fe site dopant is Nb. 5+ Zr 4+ Ti 4+ One or more of the corresponding compounds; the carbon source is one or more of glucose, sucrose, and citric acid; the iron salt is one or more of ferric nitrate and ferrous acetate; the template agent is one or more of P123 and F127; the inlet air temperature of the spray dryer is 200-230℃, and the outlet air temperature is 90-110℃.

10. A magnetically induced ordered orientation solid-state lithium battery cathode-electrolyte integrated membrane, characterized in that, It is prepared by the method for preparing a solid-state lithium battery cathode-electrolyte integrated film with magnetic field-induced ordered orientation as described in any one of claims 1-9.

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