Flame retardant, priming coat, preparation method of priming coat and positive plate

Abstract

The invention belongs to the technical field of battery technology, and provides a flame retardant, a priming coat and a preparation method thereof, and a positive plate, the flame retardant is an anion intercalation modified magnesium-aluminum layered double hydroxide; the interlayer spacing of the anion intercalation modified magnesium-aluminum layered double hydroxide is 0.76 to 3.1 nm. According to the flame retardant, magnesium-aluminum layered double hydroxide has a specific intercalation layer spacing through anion intercalation modification, the material layer spacing is increased, a difunctional nano barrier layer with flame retardance and ion conduction is constructed, and a traditional halogen-containing flame retardant is replaced. The flame retardant is prepared into priming coat slurry, coating of the slurry is completed through step drying, and the flame retardant is directionally arranged on the surface of a current collector through three different drying modes to achieve vertical orientation; compared with an ineffective distribution prime coat material in the prior art, the heat shrinkage rate of the prime coat mode is reduced, and the interface flame retardance is reduced.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a flame retardant, a base coating and its preparation method, and a positive electrode. Background Technology

[0002] Battery technology is a crucial technology in the development of new energy. However, batteries can experience a rapid temperature increase under external forces, leading to deflagration and severe damage. Therefore, flame-retardant technology for batteries has also been developed. Traditional flame-retardant technologies have certain drawbacks. For example, current lithium battery flame retardants often contain halogens (such as hexabromocyclododecane), which release toxic gases during combustion, violating environmental trends (RoHS / REACH directives). The addition of flame retardants can also negatively impact battery performance. For instance, directly adding flame retardants to the positive electrode slurry reduces ionic conductivity and specific capacity. The migration of halogen-containing flame-retardant coatings, such as bromine-based flame retardants, can lead to electrolyte contamination, affecting cell cycle performance and needle penetration resistance. Furthermore, the battery manufacturing process also affects performance. Undercoating methods can reduce performance loss. Conventional undercoatings have weak interfacial adhesion to the active material layer, poor interfacial stability, and low peel strength, making the undercoating prone to delamination after battery cycling.

[0003] Therefore, improving the flame retardancy and manufacturing methods of batteries has become an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a flame retardant, a base coating and its preparation method, and a positive electrode.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a flame retardant, wherein the flame retardant is an anionic intercalated modified magnesium-aluminum layered double hydroxide; The intercalation spacing of the anion-intercalated modified magnesium-aluminum layered double hydroxide is 0.76~3.1 nm.

[0006] Preferably, the anion includes one or more of organic anions, biomass anions, inorganic anions, and complex anions; Organic anions include one or more of dodecyl phosphate, dodecyl sulfonic acid, and stearate.

[0007] The present invention also provides a base coating, prepared from raw materials comprising the following parts by mass: Flame retardant 0.01~99.9 parts, binder 1~30 parts, conductive agent 0.01~20 parts, additive 0.01~10 parts, solvent 40~90 parts.

[0008] Preferably, the adhesive comprises one or more of fluoropolymers, water-based adhesive systems, bio-based adhesives, and smart responsive adhesives; The conductive agent includes one or more of one-dimensional conductive agents, two-dimensional conductive agents, and zero-dimensional conductive agents; The additives include interface modifiers and / or leveling agents; The solvent includes one or more of the following: amide solvents, sulfone solvents, carbonate solvents, ionic liquids, water-based solvents, bio-based solvents, fluorinated solvents, and supercritical fluids.

[0009] The present invention also provides a method for preparing the base coating, comprising the following steps: The raw materials are prepared into a base coating slurry, and after being coated on at least one side of the current collector foil, the coating is sequentially subjected to a first drying, a second drying, and a third drying to complete the coating.

[0010] Preferably, the viscosity of the primer slurry is 1000~12000 mPa·s.

[0011] Preferably, the temperature of the first drying hot air is 78~82℃, and the time is 5~25s.

[0012] Preferably, the second drying is electric field drying or magnetic field drying; The electric field drying temperature is 100~115℃, the electric field strength is 1~3000V / cm, and the time is 0.1s~60min; The magnetic field drying temperature is 100~115℃, the magnetic field strength is 0.1~0.5T, and the time is 0.1s~120min.

[0013] Preferably, the temperature of the third drying step is 120~145℃, and the infrared intensity is 3.5~4.2kW / m. 2 The duration is 10-20 seconds.

[0014] The present invention also provides a positive electrode sheet, including the aforementioned base coating.

[0015] This invention provides a flame retardant, which is anionically intercalated modified magnesium-aluminum layered double hydroxide; the intercalation spacing of the anionically intercalated modified magnesium-aluminum layered double hydroxide is 0.76~3.1 nm. This invention provides a flame retardant that, through anion intercalation modification, gives the magnesium-aluminum layered double hydroxide a specific intercalation spacing. The increased intercalation spacing constructs a dual-functional nano-barrier layer that combines flame retardancy and ion conduction. This invention achieves a dual physical-chemical flame retardant effect. The expanded layered structure acts as a physical barrier, forming a dense carbon layer upon heating, with a lower thermal conductivity than traditional flame retardants. Chemical catalysis promotes the dehydration and char formation of the polymer matrix by the intercalated anions, increasing the char residue. The modified magnesium-aluminum layered double hydroxide contains mobile intercalated anions that exhibit directional migration characteristics under an electric field, resulting in higher ionic conductivity than traditional flame retardants, thus achieving ion conduction functionality. The flame retardant was prepared as a base coating, and the material was coated through a stepped drying process. The first drying step was low-temperature pre-curing, which delayed the evaporation of surface solvents and induced the formation of a vertically oriented structure. The second drying step involved medium-temperature orientation locking, which assisted vertical orientation under the influence of an electric or magnetic field, triggered vertical capillary flow, and strengthened the orientation of nanosheets. The third drying step involved high-temperature densification, which removed interlayer solvents, reduced interlayer spacing, and fixed the orientation direction and structure. This invention, through three different drying steps, enables the flame retardant to be oriented and vertically oriented on the surface of the current collector. Compared with the ineffective distribution of base coating materials in the prior art, the base coating method of this invention reduces the thermal shrinkage rate and decreases the interfacial flame retardancy.

[0016] This invention develops a multifunctional cathode substrate material that combines halogen-free flame retardancy, interface stability, and electrolyte purification through a flame retardant with a specific structure and surface energy modulation technology. This technology can improve battery performance, including flame retardancy, cycle performance, and needle penetration pass rate. Detailed Implementation

[0017] This invention provides a flame retardant, which is an anionic intercalated modified magnesium-aluminum layered double hydroxide.

[0018] In this invention, the intercalation spacing of the anion-intercalated modified magnesium-aluminum layered double hydroxide is preferably 0.76~3.1 nm, more preferably 1~2.8 nm, and even more preferably 1.8~2 nm.

[0019] In this invention, the magnesium-aluminum layered double hydroxide is MgAl-LDH, which can be commercially available or synthesized in the laboratory. For commercial purchase: industrial-grade LDH powder with a Mg / Al molar ratio of 1.5~3:1 and a particle size D50≤500nm is selected. For laboratory synthesis: a co-precipitation method is used, specifically: Mg(NO3)2·6H2O and Al(NO3)3·9H2O are dissolved in CO2-free water at the target molar ratio; a mixed alkaline solution of NaOH / Na2CO3 is added dropwise under nitrogen protection, controlling the pH at 10.0±0.2; crystallization is carried out at 60℃ for 18h, followed by centrifugation and washing until the conductivity is <50μS / cm.

[0020] In this invention, the source of the anions is an intercalating agent, and the anions include one or more of organic anions, biomass anions, inorganic anions, and composite anions. Organic anions include one or more of dodecyl phosphate, dodecyl sulfonic acid, stearate, 2-carboxyethylphenylphosphonic acid (CEPA), and aminotrimethylenephosphonic acid (ATMP). Biomass anions include, but are not limited to, phytate, humic acid, lignin sulfonate (LS), tartaric acid, and alginic acid. Inorganic anions include one or more of phosphomolybdate, silicotungstic acid, tetraborate, and fluoroborate. Composite anions include, but are not limited to, nitrate, molybdate, sodium dodecyl sulfate, and citrate.

[0021] In this invention, the preparation method of the flame retardant includes, but is not limited to, the following methods: co-precipitation, hydrothermal, ion exchange, reconstruction, or microwave-assisted method.

[0022] In this invention, the coprecipitation method comprises the following steps: A flame retardant is obtained by mixing a magnesium-aluminum layered double hydroxide solution with an intercalating agent and then crystallizing the mixture.

[0023] In this invention, the molar ratio of the magnesium-aluminum layered double hydroxide and the intercalating agent is preferably 1:0.1~5, more preferably 1:0.5~3, and even more preferably 1:1~2.

[0024] In this invention, the concentration of the magnesium-aluminum layered double hydroxide solution is preferably 0.2~0.6M, more preferably 0.35~0.45M.

[0025] In this invention, the pH of the mixture is preferably 9.5-10, more preferably 9.6-9.9, and even more preferably 9.7-9.8.

[0026] In this invention, the crystallization temperature is preferably 60-70°C, more preferably 62-68°C, and even more preferably 64-66°C; the time is preferably 15-20 hours, more preferably 16-19 hours, and even more preferably 17-18 hours. After crystallization, the mixture is washed with water until neutral to obtain a flame retardant.

[0027] In this invention, the hydrothermal method includes the following steps: The flame retardant is obtained by hydrothermal reaction of the coprecipitated precursor with the intercalating agent.

[0028] In this invention, the coprecipitation precursor is prepared as follows: 1) Mg(NO3)2·6H2O and Al(NO3)3·9H2O are dissolved in deionized water at a ratio of Mg / Al = 2.0:1, with a total metal ion concentration of 0.5 mol / L. Under nitrogen protection, 2.0 mol / L NaOH solution is added dropwise at a rate of 2.0 mL / min, maintaining the pH at 10.0 ± 0.1; after aging for 3 h, the coprecipitation precursor is obtained by centrifugation.

[0029] In this invention, the molar ratio of Al(NO3)3·9H2O to the intercalating agent is preferably 1:0.1~5, more preferably 1:0.5~3, and even more preferably 1:1~2.

[0030] In this invention, the temperature of the hydrothermal reaction is preferably 100~150℃, more preferably 110~140℃, and even more preferably 120~130℃; the time is preferably 12~48h, more preferably 20~40h, and even more preferably 25~35h; after the reaction is completed, the flame retardant is obtained by supercritical carbon dioxide drying.

[0031] In this invention, the ion exchange method includes the following steps: Precursor pretreatment raw material: MgAl-CO3 prepared by co-precipitation method 2- LDH (Mg / Al = 2.0:1, specific surface area ≥ 150m²) 2 / g) was activated by dehydration at 80°C for 4 hours under vacuum conditions (≤0.1MPa), during which the interlayer spacing increased from 0.76nm to 0.89nm.

[0032] Phytic acid solutions with a concentration of 0.1~1M were used as the exchange solution.

[0033] Activated MgAl-CO3 2- LDH reacts with phytic acid solution.

[0034] MgAl-CO3 2-The solid-liquid ratio of LDH to phytic acid solution is preferably 1:5~20, more preferably 1:8~15. The pH is controlled at 3~5.5, and a pulse feeding method is used: 20% of the total phytic acid is injected every 30 minutes, with real-time monitoring of the ORP value at -150mV~-200mV (to prevent reducing side reactions). The reaction temperature is preferably 50~90℃, more preferably 60~80℃; the reaction time is preferably 2~12h, more preferably 4~8h. After the reaction, centrifugation, washing, and drying are performed sequentially; the centrifugation speed is preferably 7000~9000rpm, more preferably 7500~8500rpm, more preferably 8000rpm; the time is preferably ≥10min, more preferably ≥15min, more preferably ≥20min. The washing solution is a mixture of ethanol and water, with a volume ratio of ethanol to water of 7:3. The drying pressure is preferably 5~15MPa, more preferably 6~14MPa, and even more preferably 8~12MPa; the temperature is preferably 30~40℃, more preferably 32~38℃, and even more preferably 34~36℃; the time is preferably ≥6h, more preferably ≥7h, and even more preferably ≥8h.

[0035] In this invention, the reconstruction method includes the following steps: The magnesium-aluminum layered double hydroxide was calcined to obtain an oxide, which was then added to an intercalating agent solution for reconstruction to obtain a flame retardant.

[0036] In this invention, the molar ratio of the magnesium-aluminum layered double hydroxide and the intercalating agent is preferably 1:0.2~1.3, more preferably 1:0.3~1.2, and even more preferably 1:0.5~1.

[0037] In this invention, the concentration of the intercalating agent solution is preferably 50-120 g / L, more preferably 60-110 g / L, and even more preferably 80-90 g / L.

[0038] In this invention, the calcination temperature is preferably 400~500℃, more preferably 420~480℃, and even more preferably 440~460℃; the time is preferably 1~3h, more preferably 1.5~2.5h, and even more preferably 1.8~2.2h; the reconstruction temperature is preferably 20~30℃, more preferably 22~28℃, and even more preferably 24~26℃; the time is preferably 2~6h, more preferably 3~5h, and even more preferably 3.5~4.5h.

[0039] In this invention, the microwave-assisted method includes the following steps: A flame retardant is obtained by reacting a mixture of magnesium-aluminum layered double hydroxide, an intercalating agent, and a solvent.

[0040] In this invention, the molar ratio of magnesium-aluminum layered double hydroxide to intercalating agent is preferably 1:0.05~0.5, more preferably 1:0.1~0.4, and even more preferably 1:0.2~0.3; the solvent is an aqueous ethanol solution, and the volume fraction of the solvent is preferably 30~50%, more preferably 35~45%, and even more preferably 38~42%; the mass ratio of magnesium-aluminum layered double hydroxide to intercalating agent and to solvent is preferably 1:18~25, more preferably 1:19~24, and even more preferably 1:20~23.

[0041] In this invention, the microwave radiation power of the reaction is preferably 700-900W, more preferably 750-850W, and even more preferably 780-820W; the temperature is preferably 70-90℃, more preferably 75-85℃, and even more preferably 78-82℃; the pulse heating on-time is preferably 20-40s, more preferably 25-35s, and even more preferably 28-32s; the off-time is preferably 5-15s, more preferably 6-14s, and even more preferably 8-12s; and the total time is preferably 5-15min, more preferably 6-14min, and even more preferably 8-12min.

[0042] The present invention also provides a base coating, prepared from raw materials comprising the following parts by mass: Flame retardant 0.01~99.9 parts, binder 1~30 parts, conductive agent 0.01~20 parts, additive 0.01~10 parts, solvent 40~90 parts.

[0043] In this invention, the flame retardant is preferably present in parts by weight of 1 to 99, for example, 1, 2, 5, 10, 12, 15, 18, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, or 99.

[0044] In this invention, the adhesive is preferably in the form of 5 to 25 parts by weight, for example, 5 parts, 6 parts, 7 parts, 8 parts, 10 parts, 15 parts, 20 parts, or 25 parts.

[0045] In this invention, the conductive agent is preferably in the form of 1 to 18 parts by mass, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, or 18 parts.

[0046] In this invention, the preferred mass fraction of the additive is 0.5 to 9 parts, for example, 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, or 9 parts.

[0047] In this invention, the solvent is preferably in the range of 45 to 65 parts by mass, for example, 45 parts, 50 parts, 52 parts, 55 parts, 58 parts, 60 parts, or 65 parts.

[0048] In this invention, the adhesive comprises one or more of fluoropolymers, water-based adhesive systems, bio-based adhesives, and smart responsive adhesives.

[0049] In this invention, the fluoropolymer is one or more of PVDF, PTFE modified emulsion and PVDF-HFP; the fluoropolymer is a conventional product that can be purchased from the market by those skilled in the art.

[0050] In this invention, the water-based adhesive system is one or more of styrene-butadiene rubber, carboxymethyl cellulose, polyacrylic acid, lithium polyacrylate, and sodium polyacrylate.

[0051] In this invention, the bio-based binder is one or more of chitosan quaternary ammonium salt, sodium alginate, and lithium alginate.

[0052] In this invention, the smart responsive binder comprises a thermally expanding microsphere binder and / or a polyionic liquid.

[0053] In this invention, the thermally expandable microsphere binder is commercially available, specifically from AkzoNobel, Matsumoto Yushi Pharmaceutical, and Clariant, among others.

[0054] In this invention, the polyionic liquids are commercially available, specifically Solvay, Cyphos® series (phosphorus-based ionic liquids); Iolitec, PIL-001 (vinylimidazolium polymers); and Sigma-Aldrich, poly(1-vinyl-3-ethylimidazolium bromide).

[0055] In this invention, the conductive agent comprises one or more of one-dimensional conductive agents, two-dimensional conductive agents, and zero-dimensional conductive agents.

[0056] In this invention, the one-dimensional conductive agent is one or more of single-arm carbon nanotubes, multi-arm carbon nanotubes, carboxylated carbon nanotubes, and carbon fibers.

[0057] In this invention, the two-dimensional conductive agent is one or more of graphene, MXene, and MOF.

[0058] In this invention, the zero-dimensional conductive agent is Ketjen Black and / or silver-coated copper powder.

[0059] In this invention, the additive comprises an interface modifier and / or a leveling agent.

[0060] In this invention, the interface modifier is one or more of the following: silane coupling agents (KH-550 aminosilane, Si-747 (fluorinated alkylsilane) etc.), titanates (NDZ-201 (pyrophosphate type) etc.), ionic liquids, supramolecular assembly agents (cucurbita), rare earth additives (cerium nitrate (Ce(NO3)3), bio-based interface agents (tea polyphenol-iron complex) and nano-bridging agents (Al2O3@GO core-shell structure etc.); the interface modifier is a conventional product that can be purchased from the market by those skilled in the art.

[0061] In this invention, the solvent comprises one or more of the following: amide solvents (N-methylpyrrolidone, dimethylacetamide), sulfone solvents (sulfolane), carbonate solvents (propylene carbonate), ionic liquids ([BMIM][Tf2N]), water-based solvents (deionized water, 2-butoxyethanol), bio-based solvents (γ-valerolactone), fluorinated solvents (nonafluorohexylmethyl ether), and supercritical fluids (supercritical CO2).

[0062] The present invention also provides a method for preparing the base coating, comprising the following steps: The raw materials are prepared into a base coating slurry, and after being coated on at least one side of the current collector foil, the coating is sequentially subjected to a first drying, a second drying, and a third drying to complete the coating.

[0063] In this invention, the viscosity of the primer slurry is preferably 1000~12000 mPa·s, more preferably 3000~8000 mPa·s, and even more preferably 4000~6000 mPa·s.

[0064] In this invention, the current collector foil needs to be pretreated before use. The pretreatment methods are electrolytic polishing, atmospheric pressure plasma treatment, and silane primer coating. The pretreatment methods are conventional treatment methods for those skilled in the art.

[0065] In this invention, the coating machine is a micro-gravure transfer coating machine, a nano-gravure transfer coating machine, a gravure transfer coating machine, or a slot extrusion coating machine.

[0066] In this invention, the temperature of the first drying hot air is preferably 78~82℃, more preferably 79~81℃, and even more preferably 79.5~80℃; the time is preferably 5~25s, more preferably 16~24s, and even more preferably 18~22s.

[0067] In this invention, the second drying is electric field drying or magnetic field drying.

[0068] In this invention, the temperature for electric field drying is preferably 100~115℃, more preferably 105~110℃, and even more preferably 106~108℃; the electric field strength is preferably 1~3000V / cm, more preferably 500~2500V / cm, and even more preferably 1000~2000V / cm; and the time is preferably 0.1s~60min, more preferably 10~50min, and even more preferably 20~40min.

[0069] In this invention, the temperature for magnetic field drying is preferably 100~115℃, more preferably 105~110℃, and even more preferably 106~108℃; the magnetic field strength is preferably 0.1~0.5T, more preferably 0.2~0.4T, and even more preferably 0.25~0.3T; and the time is preferably 0.1s~120min, more preferably 20~100min, and even more preferably 40~80min.

[0070] In this invention, the temperature of the third drying step is preferably 120~145℃, more preferably 125~140℃, and even more preferably 130~135℃; the infrared intensity is preferably 3.5~4.2kW / m². 2 Further preferred is 3.6~4.1kW / m 2 More preferably, it is 3.8~3.9kW / m 2 The time is preferably 10-20s, more preferably 12-18s, and even more preferably 14-16s; the third drying is carried out in a protective atmosphere, preferably nitrogen, helium, or argon.

[0071] The present invention also provides a positive electrode sheet, including the aforementioned base coating.

[0072] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0073] Example 1

[0074] Preparation of dodecyl phosphate intercalated MgAl-LDH (phosphate ester@MgAl-LDH) flame retardant: Disperse MgAl-LDH in an ethanol solution of dodecyl phosphate (mass ratio of MgAl-LDH to dodecyl phosphate is 1:0.5) → Add an appropriate amount of triethylamine (10 mL of triethylamine per 100 g MgAl-LDH) → reflux at 80 °C for 6 h under nitrogen protection (ion exchange reaction) → centrifuge after reaction → wash with anhydrous ethanol until the conductivity of the filtrate is <5 μS / cm → place the product in a vacuum drying oven and activate at 80 °C for 12 h → sieve (400 mesh) to obtain the final product (phosphate ester@MgAl-LDH).

[0075] The interlayer spacing of phosphate ester@MgAl-LDH is 2.83 nm; XRD characteristic peak data: The original MgAl-LDH has a (003) crystal plane peak position (2θ) of 11.60°, a full width at half maximum (FWHM) of 0.32°, and an interlayer spacing (d) of 0.76 nm.

[0076] Phosphate ester@MgAl-LDH: (003) crystal plane peak position (2θ) is 3.12°, half width at half maximum (FWHM) is 0.18°, and interlayer spacing (d) is 2.83 nm.

[0077] Primer formulation: Flame retardant (phosphate ester @MgAl-LDH): Binder (PVDF-HFP): Conductive agent (carbon nanotubes): Additive 1 (dispersant BYK-2150): Dispersant 2 (thickener CMC): Solvent (NMP) = 20.0: 12.0: 1.0: 0.5: 0.3: 66.2 (mass ratio).

[0078] Step 1: Pre-dispersed solvent system

[0079] Solvent pretreatment: Add 66.2 g of NMP solvent to the reactor and heat to 40°C (to reduce subsequent viscosity). Add 0.3 g of thickener CMC and stir at 500 rpm for 20 min until fully swollen.

[0080] Step 2: Primary dispersion of conductive agent

[0081] Carbon nanotube (CNT) activation: In another container, mix: 1.0 g carbon nanotubes; 0.5 g dispersant BYK-2150; add 5 g NMP (additional) (extra-formula auxiliary solvent); treat with an ultrasonic cell disruptor (200 W, 15 min, on / off pulse ratio 5 s / 2 s).

[0082] Step 3: Mix the main materials in stages

[0083] Adhesive dissolution: Add 12.0 g PVDF-HFP to the CMC / NMP system in step 1; stir under vacuum (800 rpm, 60℃, 1 h) until a transparent adhesive solution is obtained.

[0084] Flame retardant intercalation dispersion: Slowly add 20.0 g phosphate ester@MgAl-LDH; high-speed shear emulsification (10,000 rpm, 30 min), control the slurry temperature ≤50℃.

[0085] Step 4: Gradient Mixing and Viscosity Control

[0086] Stepwise compounding: Add the CNT dispersion from step 2 to the main system and stir with scraping (300 rpm, 10 min); planetary stirring, revolution at 30 rpm + rotation at 1500 rpm; vacuum degassing, -0.095 MPa, 20 min.

[0087] Viscosity calibration: real-time monitoring using a rotational viscometer (rotor model LV-3, 30 rpm).

[0088] If the viscosity is >4500 mPa·s: add 1-2% NMP and stir for 10 min; if the viscosity is <3500 mPa·s: add 0.1-0.2% CMC and shear emulsify for 5 min.

[0089] The viscosity of the primer slurry is 4000 mPa·s.

[0090] Current collector foil pretreatment: The substrate is 10μm aluminum foil, which is treated by atmospheric pressure plasma with parameters of Ar / O2=9:1, 200W, and 10m / min.

[0091] Coating machine: Slot extrusion coating machine.

[0092] Coating process: Coating → First drying (80℃ hot air drying for 20s) → Second drying (110℃, applying a 200V / cm DC electric field for 35s to assist orientation) → Third drying (140℃ infrared irradiation at 4kW / m²) 2 (Cure for 15 seconds, then protect with N2).

[0093] Performance testing: The vertical orientation XRD (003) / (110) strength test of the flame retardant (phosphate ester @MgAl-LDH) passed the XRD test; the heat shrinkage rate test of the corresponding electrode was conducted in accordance with the GB / T 3076-2018 (150℃ / 1h) test standard; the interfacial impedance test of the electrode was conducted in accordance with the EIS test (0.1~10). 5 The test standard is Hz (amplitude 5mV); the safety performance of the alkali metal ion battery assembled with the electrode is tested according to the GB 31241-2022 needle penetration test standard; the flame retardancy rating is based on UL94 (0.5mm thickness). The electrode and battery test results are the changes compared to the blank control group (without the base coating), and the results are recorded in Table 1.

[0094] Table 1 Test Results of Example 1

[0095] Example 2

[0096] Preparation of phytic acid / boric acid bis-anionic intercalated MgAl-LDH (phytic acid / boric acid@MgAl-LDH) flame retardant: Mixed solution (phytic acid concentration 0.1M, boric acid concentration 0.2M) → pH adjusted to 7.8 with NH3·H2O → 1g precursor MgAl-LDH added → hydrothermal treatment at 80℃ for 24h → washing with hot water at 60℃ → freeze-drying → white powder (phytic acid / boric acid@MgAl-LDH)

[0097] Phytate intercalation increased the interlayer spacing from 0.77 nm to 1.65 nm (corresponding to 2θ changing from 11.5° to 5.35°), with an interlayer expansion rate of 114%.

[0098] The secondary intercalation of borate further expands the interlayer spacing to 2.07 nm (2θ 4.26°), forming a stable sandwich structure (the interlayer height can accommodate two anions), as shown in Table 2.

[0099] Table 2. Layer spacing data results

[0100] EDS surface scan element distribution

[0101] P and B elements are uniformly co-distributed in the LDH layers (no phase separation in the mapping diagram).

[0102] P≈1:1.2 (consistent with the feed ratio), proving that the bi-anion synchronous stable intercalation is achieved. The specific results are shown in Table 3.

[0103] Table 3 EDS Scan Results

[0104] Synchrotron XANES spectrum (boron K-edge)

[0105] The K-edge absorption peak of boron shifted from 194.2 eV (neutral H3BO3) to 196.8 eV.

[0106] The increase in energy proves that boron is negatively charged [B(OH)4] The tetrahedral configuration exists (due to electrostatic interaction with the positive charge of the laminations), and the specific results are shown in Table 4.

[0107] Table 4. Synchrotron XANES Spectrum Results

[0108] A stepwise intercalation strategy, first phytate and then borate, was employed. XRD characterization confirmed that the interlayer spacing expanded to 1.65 nm after phytate insertion, followed by a second intercalation of borate, resulting in a final interlayer spacing of 2.07 nm, forming a stable "sandwich" structure. EDS surface scanning analysis showed that the P / B atomic ratio remained stable at 1:1.2 (±0.05), demonstrating a uniform distribution of the two anions in the interlayer. Synchrotron XANES spectroscopy confirmed that the borate ion exists in a [B(OH)4]- tetrahedral configuration.

[0109] Primer formulation

[0110] Flame retardant (phytic acid / boric acid@MgAl-LDH): binder (polyacrylate emulsion): conductive agent (carboxylated carbon nanotubes): additives: solvent (ethanol / deionized water at a ratio of 1:1) = 8.0:1.8:0.7:0.2:89.3 (mass ratio), wherein the additives include polyether-modified polysiloxane BYK-349, hydroxyethyl cellulose, and acetylenol surfactant (model Air Products Surfynol® 104), with a mass ratio of 0.12:0.06:0.02.

[0111] The viscosity of the slurry is 2800 mPa·s.

[0112] The substrate is 15μm aluminum foil, treated by atmospheric pressure plasma, with parameters of Ar / =9:1, 300W, 10m / min.

[0113] Coating machine: Microgravure transfer coating machine.

[0114] Coating process: First drying (80℃ hot air drying for 20s) → Second drying (105℃, applying a 300V / cm DC electric field for 35s to assist orientation) → Third drying (140℃ infrared irradiation at 4kW / m²) 2 (Cure for 20 seconds, then protect with N2).

[0115] The same standards as in Example 1 were used for testing, and the results are recorded in Table 5.

[0116] Table 5 Test Results of Example 2

[0117] Example 3

[0118] Preparation of tartrate-intercalated MgAl-LDH (tartaric acid@MgAl-LDH) flame retardant: Mg(NO3)2·6H2O:Al(NO3)3·9H2O:Na2C4H4O6=3:1:0.8 (molar ratio) Hydrothermal conditions: reaction at 100℃ for 36 hours, pH value precisely controlled at 9.2±0.1.

[0119] The XRD test results are shown in Table 6.

[0120] Table 6 XRD Test Results

[0121] 1. Structural verification analysis

[0122] Evidence for interlayer spacing expansion: Precursor (NO3) - The MgAl-LDH (003) peak is located at ~11.5° (d=0.77 nm). After tartaric acid intercalation, the (003) peak shifted to 4.79° (d=1.84 nm), and the interlayer spacing increased by 139%; which is consistent with the theoretical size of vertically aligned tartrate ions (molecular length≈1.2 nm + layer thickness≈0.48 nm).

[0123] 2. Crystal structure integrity

[0124] The (006) peak is located at 9.58° (4.79°×2), which is consistent with the diffraction pattern of the R-3m space group of LDH crystal; The sharp (110) peak (60.5°) indicates that the two-dimensional order of the layer is not destroyed.

[0125] 3. Elimination of impurity phases

[0126] No characteristic peaks of Al(OH)3 (18.3°, 20.2°, 36.8°); No characteristic peaks of Mg(OH)2 (38.0°, 50.8°, 58.6°).

[0127] 4. Calculation process for interlayer spacing

[0128] According to Bragg's equation: nλ = 2d sinθ (λ = Cu Kα radiation wavelength = 0.15406 nm).

[0129] For the (003) crystal plane (n=1): d 003 =λ / (2×sinθ)=0.15406 / (2×sin(4.79° / 2))=0.15406 / (2×0.0418)=1.84 nm.

[0130] 5. XRD data proves: Tartrate ions were successfully inserted into the LDH interlayer, forming an ultra-large interlayer spacing structure of 1.84 nm; The crystal structure is intact, with no impurity phases formed. The orderliness of the lamellae is maintained ((110) peak is sharp).

[0131] Product characteristics: XRD shows that the (003) interplanar spacing has increased to 1.84 nm (average).

[0132] Primer formulation

[0133] Flame retardant (tartaric acid@MgAl-LDH): binder (polyetherimide): conductive agent (titanium carbide MXene): additives: solvent (deionized water) = 15.0:3.9:1.2:0.1:79.8 (mass ratio); additives include dispersant, sodium polycarboxylate (FS-2022N); defoamer, polyether-modified siloxane (BYK-093); leveling agent, alkyl-modified organosilicon (TEGO-148), with a mass ratio of 0.06:0.03:0.01.

[0134] The viscosity of the slurry is 3200 mPa·s.

[0135] Current collector foil pretreatment: The substrate is 12μm aluminum foil, which is electrolytically polished with H3PO4 parameters. 42 O=1:3, 25℃, 30s.

[0136] Coating machine: Microgravure coating machine.

[0137] Coating process: Coating → First drying (80℃ hot air drying for 5s) → Second drying (0.3T magnetic field orientation for 30s) → Third drying (120℃ infrared curing for 10s, nitrogen atmosphere).

[0138] The same standards as in Example 1 were used for testing, and the results are recorded in Table 7.

[0139] Table 7 Test Results of Example 3

[0140] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A flame retardant, characterized in that, The flame retardant is an anionic intercalated modified magnesium-aluminum layered double hydroxide; The intercalation spacing of the anion-intercalated modified magnesium-aluminum layered double hydroxide is 0.76~3.1 nm.

2. The flame retardant as described in claim 1, characterized in that, The anions include one or more of organic anions, biomass anions, inorganic anions, and complex anions; Organic anions include one or more of dodecyl phosphate, dodecyl sulfonic acid, and stearate.

3. A base coating, characterized in that, It is prepared from raw materials comprising the following parts by mass: The flame retardant of claim 1 or 2 comprises 0.01 to 99.9 parts, the binder comprises 1 to 30 parts, the conductive agent comprises 0.01 to 20 parts, the additive comprises 0.01 to 10 parts, and the solvent comprises 40 to 90 parts.

4. The base coating as described in claim 3, characterized in that, The adhesive comprises one or more of fluoropolymers, water-based adhesive systems, bio-based adhesives, and smart responsive adhesives; The conductive agent includes one or more of one-dimensional conductive agents, two-dimensional conductive agents, and zero-dimensional conductive agents; The additives include interface modifiers and / or leveling agents; The solvent includes one or more of the following: amide solvents, sulfone solvents, carbonate solvents, ionic liquids, water-based solvents, bio-based solvents, fluorinated solvents, and supercritical fluids.

5. The method for preparing the base coating according to claim 3 or 4, characterized in that, Includes the following steps: The raw materials are prepared into a base coating slurry, and after being coated on at least one side of the current collector foil, the coating is sequentially subjected to a first drying, a second drying, and a third drying to complete the coating.

6. The method for preparing the base coating as described in claim 5, characterized in that, The viscosity of the primer slurry is 1000~12000 mPa·s.

7. The method for preparing the base coating as described in claim 5, characterized in that, The temperature of the first drying hot air is 78~82℃, and the time is 5~25s.

8. The method for preparing the base coating as described in claim 5, characterized in that, The second drying method is electric field drying or magnetic field drying; The electric field drying temperature is 100~115℃, the electric field strength is 1~3000V / cm, and the time is 0.1s~60min; The magnetic field drying temperature is 100~115℃, the magnetic field strength is 0.1~0.5T, and the time is 0.1s~120min.

9. The method for preparing the base coating as described in claim 5, characterized in that, The third drying process is carried out at a temperature of 120~145℃ and an infrared intensity of 3.5~4.2kW / m². 2 The duration is 10-20 seconds.

10. A positive electrode plate, characterized in that, Includes the base coating as described in claim 3 or 4.

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