Alpha-zrp-conductive polymer composite coated lithium-rich manganese-based positive electrode material, preparation method thereof and solid-state battery

Abstract

The application discloses an alpha-ZrP-conductive polymer composite-coated lithium-rich manganese-based positive electrode material, a preparation method thereof and solid-state battery application. The material takes a bulk-modified lithium-rich manganese-based material as a core, and a composite coating layer composed of exfoliated alpha-ZrP nanosheets and a conductive polymer is constructed on the surface of the core. The composite coating layer can realize internal proton self-exchange response based on the solid acid characteristics of alpha-ZrP and the conductive polymer, and a "viaduct type" fast ion-electron dual transmission channel is formed in the material. Meanwhile, the coating layer acts as a dense physical and chemical barrier, effectively blocking the harmful side reactions between the positive electrode and the solid-state electrolyte. When the positive electrode material prepared by the application is applied to a solid-state battery, high first-cycle coulomb efficiency, excellent cycle stability and rate performance are exhibited, and the two core problems of interface instability and slow kinetics of the lithium-rich manganese-based material in the solid-state battery are effectively solved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to a modified lithium-rich manganese-based cathode material suitable for high-energy-density, high-safety solid-state batteries, its preparation method, and a solid-state battery containing the cathode material. Background Technology

[0002] Lithium-rich manganese-based cathode materials (with the general molecular formula xLi2MnO3·(1-x)LiTMO2, where TM is one or more transition metal elements such as Ni, Co, Mn, and Al) have a capacity exceeding 250 mAh g⁻¹. -1 The theoretical specific capacitance and higher than 3.5V (vs. Li) + The average operating voltage of / Li is considered to be the key to achieving a breakthrough in the energy density of next-generation lithium-ion batteries (≥400 Whkg). -1 It is one of the key cathode materials. However, the inherent chemical and electrochemical instability of this material severely restricts its commercial application, especially in all-solid-state batteries that use solid electrolytes such as sulfides and halides, where these problems are further amplified and intensified.

[0003] Severe interfacial side reactions: During the initial charging to high voltage (>4.5V), the Li2MnO3 component in the lithium-rich material is activated, accompanied by irreversible precipitation of lattice oxygen, generating highly reactive oxygen species (such as O2). n-1 Meanwhile, residual lithium compounds such as Li₂CO₃ and LiOH present on the material surface can react with solid electrolytes such as sulfides and halides (e.g., Li₆PS₅Cl, Li₂O₂) that have narrow chemical potential windows and are extremely sensitive to oxidation potentials. 10 GeP2S 12 Li3InCl6 undergoes a violent redox reaction to produce Li2S and P2S. x A series of high-resistivity interfacial decomposition products, such as metal chlorides / oxides, are produced. This interfacial layer not only severely hinders lithium-ion transport, leading to huge interfacial impedance and capacity decay, but also continuously consumes active lithium and electrolyte, causing rapid deterioration of battery performance.

[0004] Poor solid-solid interface contact: Unlike liquid electrolytes, which can wet and fill the pores of electrode particles, the rigid solid-solid contact in solid-state batteries results in a limited physical contact area between the positive electrode active material, conductive agent and solid electrolyte, which hinders ion transport pathways, leading to high local current density and significant charge-discharge polarization, severely limiting rate performance and full capacity utilization.

[0005] The intrinsic kinetics of the material are slow: the electronic conductivity of lithium-rich materials is (~10) -10 S cm -1) and lithium-ion diffusion coefficient (~10 -12 cm 2 s -1 The capacity is relatively low. The problem of slow bulk charge transport kinetics is more pronounced in solid-state batteries in the absence of liquid electrolyte permeation to provide ion transport pathways, leading to a sharp drop in capacity at high rates.

[0006] Currently, surface coating is one of the most effective strategies for improving the stability of the cathode / solid electrolyte interface. However, traditional single-component coatings have significant limitations and cannot meet the stringent interface requirements of solid-state batteries.

[0007] Ion-conducting but electronically insulating coatings (such as Li2ZrO3, Li3PO4, Al2O3, LiNbO3): Although they can block side reactions to a certain extent and provide lithium-ion transport paths, their electronic insulation severely hinders electron tunneling and significantly increases the charge transfer impedance of the electrode. Especially with thick coatings, they severely sacrifice rate performance and power density.

[0008] Electron-conducting but ion-insulating coatings (such as amorphous carbon, graphene, and conductive polymers): While they can improve the electronic conductivity network, their physical isolation of highly reactive oxygen species and residual lithium is limited. They cannot effectively suppress their oxidative attack on the solid electrolyte and may even trigger additional side reactions due to their own reducing properties. Furthermore, these coatings do not contribute to lithium-ion transport and may even hinder ion diffusion, leading to increased polarization.

[0009] Therefore, developing a multifunctional synergistic coating layer that can simultaneously achieve efficient lithium-ion conduction, rapid electron transport, and strong interfacial physicochemical isolation is key to overcoming the bottleneck of lithium-rich manganese-based cathode materials in solid-state batteries and unleashing their high energy density potential. Summary of the Invention

[0010] One of the objectives of this invention is to provide a lithium-rich manganese-based cathode material with layered zirconium phosphate (α-ZrP)-conductive polymer composite coating. This material fundamentally solves the two core challenges of interfacial instability and slow charge transport kinetics in lithium-rich materials in solid-state batteries by constructing a unique "interchange-type" ion-electron dual channel and a dense physicochemical barrier.

[0011] The second objective of this invention is to provide a method for preparing the above-mentioned cathode material, which is simple in process, mild in conditions, and produces uniform and controllable coating, making it suitable for large-scale production.

[0012] The third objective of this invention is to provide a high-performance, long-life solid-state battery containing the above-mentioned cathode material, and to clarify its key assembly process parameters.

[0013] To achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0014] In the first aspect, the present invention provides a lithium-rich manganese-based cathode material coated with α-ZrP-conductive polymer composite. The material uses a bulk-phase modified lithium-rich manganese-based material as the core, and a composite coating layer of α-ZrP-conductive polymer is coated on the surface of the core.

[0015] The general formula of the bulk-phase modified lithium-rich manganese-based material is xLi2MnO3·(1-x)LiTM 1-y M y O 2-z N z , where 0 < x < 1, 0.005 < y < 0.05, 0.001 < z < 0.05, TM is Ni, Co, and Mn, M is selected from one or more of Al, Ti, Zr, Ru, Mg, W, Mo, Nb, Y, Yb, Ce, Sn, and N is selected from one of F, Cl, S, P, B.

[0016] The bulk-phase modification is element doping, and the doping elements are selected from one or more of Al, Ti, Zr, Ru, Mg, W, Mo, Nb, Y, Yb, Ce, Sn, F, Cl, S, P, B, preferably Al / F co-doping, Mg / F co-doping, and more preferably Al / F co-doping. The doping aims to stabilize the lattice structure, inhibit phase change and oxygen loss during cycling, and improve the structural stability and intrinsic electronic conductivity of the material.

[0017] In the composite coating layer, α-ZrP exists in the form of partially exfoliated nanosheets and is tightly combined with the conductive polymer through protonation, hydrogen bonding, and / or π-π interaction to form an organic-inorganic hybrid nanocomposite, constituting a synergistic coating structure that simultaneously provides fast lithium-ion transport channels and electron transport channels.

[0018] The conductive polymer is preferably polyaniline (PANI) or polypyrrole (PPy).

[0019] Preferably, the mass ratio of α-ZrP to the conductive polymer is 10:1 to 1:1. Within this ratio range, it can ensure sufficient ion channel density and barrier effect, and form a continuous and efficient electron conductive network.

[0020] Preferably, the total mass of the composite coating layer accounts for 0.5% to 5.0% of the mass of the core material. If the coating amount is too low, the protection effect is insufficient; if it is too high, it may hinder the entry and exit of lithium ions from the core, resulting in capacity loss and kinetic decline. The more preferred coating amount is 1.0% to 3.0%.

[0021] The functional mechanism of the composite coating layer is as follows:

[0022] 1. "Overpass-style" ion-electron dual-channel coordinated transport mechanism:

[0023] Fast ion channels: α-ZrP is a typical layered solid acid with exchangeable protons (H+) between its layers. + In an electrochemical environment, lithium ions (Li) + It can undergo ion exchange with interlayer protons, and its regular two-dimensional layered structure is Li + The migration provides an ordered potential pathway, which helps to improve the apparent ionic conductivity of the coating and Li. + The diffusion rate.

[0024] Three-dimensional electron channels: Conductive polymers (such as PANI and PPy) have poor conductivity in their intrinsic state, but their conductivity can be significantly improved by proton acid doping. α-ZrP, as a solid acid, can donate protons to PANI or PPy, transforming them into highly conductive emerald green imine salts (PANI) or polaron / bipolaron states (PPy), thereby constructing a continuous three-dimensional electron conductive network within the coating layer. This allows electrons to bypass the surface of the insulating core material and rapidly transfer through the coating layer.

[0025] Synergistic effect: The two-dimensional ion channels of α-ZrP and the three-dimensional electronic channels of the conductive polymer intertwine and permeate at the nanoscale, forming a parallel, efficient, and non-interfering dual transport network, similar to an urban overpass. This structure simultaneously solves the problem of low ionic and electronic conductivity in the core material, greatly improving electrode reaction kinetics and reducing charge-discharge polarization.

[0026] 2. Interface stability and protection mechanisms:

[0027] Physical barrier function: The uniform and dense composite coating layer acts as an ideal physical barrier layer, directly isolating the lithium-rich material particles from contact with the surrounding solid electrolyte, effectively preventing the direct oxidation and erosion of the solid electrolyte by active oxygen species released under high voltage and residual lithium compounds on the material surface.

[0028] Chemical stabilization and neutralization: α-ZrP itself possesses excellent thermal and chemical stability, and can withstand high voltage (>4.8 V) environments. Its acidic surface has a certain neutralizing effect on alkaline residues such as Li₂CO₃, generating Li₂. + H2O and CO2 help reduce reactants that cause side reactions at the source and purify the interface environment.

[0029] Stress buffering effect: The composite of a conductive polymer with a certain degree of toughness and flexibility with rigid α-ZrP nanosheets forms a coating layer that can better adapt to the stress generated by the volume change of the core material during charging and discharging, preventing the coating layer from cracking and failing due to brittleness, and maintaining its long-term structural integrity and continuous protective function.

[0030] Secondly, the present invention provides a method for preparing a lithium-rich manganese-based cathode material coated with an α-ZrP-conductive polymer composite, comprising the following steps:

[0031] Preparation and purification of S1, α-ZrP-conductive polymer composite materials:

[0032] S11, Disperse crystalline α-ZrP powder in tetrabutylammonium hydroxide (TBA) + OH - In an aqueous solution, the mixture was stirred at room temperature and then subjected to ultrasonic treatment to obtain a stable, translucent to milky white exfoliated α-ZrP nanosheet dispersion.

[0033] Preferably, the concentration of the tetrabutylammonium hydroxide aqueous solution is 0.1~1.0 mol / L, and the dispersion concentration of α-ZrP in the tetrabutylammonium hydroxide aqueous solution is 5~50 mg / mL;

[0034] Preferably, the stirring time is 6 to 24 hours;

[0035] Preferably, the ultrasonic treatment power is 300~600W and the time is 0.5~2 hours;

[0036] S12. A certain amount of conductive polymer monomer (aniline or pyrrole) is added to the exfoliated α-ZrP nanosheet dispersion. The system is cooled to 0-5°C in an ice-water bath and stirred to obtain a homogeneous mixture. An aqueous solution of an oxidant (e.g., ammonium persulfate for aniline, ferric chloride for pyrrole) is prepared and slowly added dropwise to the cooled mixture through a constant-pressure dropping funnel under vigorous stirring (e.g., 1000 rpm). The dropping rate is strictly controlled (e.g., 1-2 drops / second), and the system temperature is maintained at 0-5°C throughout the dropping process and in the early stages of the reaction using an ice-water bath. After the addition is complete, the low temperature is maintained and the reaction is stirred for 6-12 hours to allow in-situ oxidative polymerization of the monomer on the surface and between the layers of the α-ZrP nanosheets. During the reaction, characteristic color changes (aniline: turns green; pyrrole: turns black) and a gradual increase in viscosity can be observed. After the reaction, the product is centrifuged, repeatedly washed, and freeze-dried to obtain the α-ZrP-conductive polymer composite material.

[0037] Preferably, the mass ratio of the conductive polymer monomer to α-ZrP is 1:10 to 1:1;

[0038] Preferably, the oxidant solution is a pre-cooled dilute hydrochloric acid solution of ammonium persulfate (APS) to maintain the pH of the system at 1-4;

[0039] S13. After the reaction is completed, the solid product is collected by vacuum filtration or centrifugation. The product is washed repeatedly with deionized water and ethanol until the filtrate is colorless and transparent to remove reaction byproducts, unreacted monomers and oxidants. After vacuum drying, powdered α-ZrP-conductive polymer composite material is obtained.

[0040] Preferably, the drying temperature is 60~80℃ and the drying time is 6~12h;

[0041] S2. Construction of the composite coating layer:

[0042] The powdered α-ZrP-conductive polymer composite material obtained in step S1 is redispersed in a solvent to form a composite coating agent dispersion with a concentration of 0.1~5 mg / mL; a predetermined amount of bulk-modified lithium-rich manganese-based core material powder is added to the above dispersion, and it is uniformly dispersed by mechanical stirring and / or ultrasonic treatment, so that the α-ZrP-conductive polymer composite material fully and uniformly coats the surface of the core material.

[0043] Preferably, the solvent is one or more of water, ethanol, isopropanol, or N-methylpyrrolidone;

[0044] Preferably, the mechanical stirring speed is 500~800 rpm and the time is 30~60 min; the ultrasonic treatment power is 150~300W and the time is 5~15 min.

[0045] S3. Post-processing and crystallization of the product:

[0046] The coated solid product was collected by filtration or centrifugation, washed repeatedly with deionized water and ethanol, and then vacuum dried. The dried powder was then heat-treated in an inert atmosphere (such as argon or nitrogen) to obtain lithium-rich manganese-based cathode material coated with α-ZrP-conductive polymer composite.

[0047] Preferably, the drying temperature is 60~100℃ and the drying time is 6~12 hours;

[0048] Preferably, the heat treatment temperature is 200~400℃ and the heat treatment time is 2~5 hours.

[0049] This step aims to remove residual solvent, further improve the crystallinity of α-ZrP in the coating layer, enhance the conjugation degree and conductivity of the conductive polymer, and strengthen the bonding force between the coating layer and the core, ultimately obtaining a high-performance α-ZrP-conductive polymer composite-coated lithium-rich manganese-based cathode material.

[0050] Thirdly, the present invention provides a solid-state battery, comprising a positive electrode, a negative electrode and a solid electrolyte layer, wherein the positive electrode comprises the above-mentioned lithium-rich manganese-based positive electrode material coated with α-ZrP-conductive polymer composite, a solid electrolyte and conductive carbon black.

[0051] Solid electrolyte layer: composed of halide solid electrolytes (such as Li3InCl6, Li3YCl6 or Li3YBr6).

[0052] Negative electrode: composed of at least one of metallic lithium, lithium alloy, silicon-based material or graphite.

[0053] Beneficial effects:

[0054] Synergistic interface protection significantly improves battery life: Through the physical isolation and chemical stabilization of α-ZrP, and the flexible filling of conductive polymers, a robust and stable cathode / electrolyte interface is constructed, significantly suppressing side reactions from both physical and chemical perspectives. This results in a substantial improvement in the first-cycle coulombic efficiency of the solid-state battery (reaching over 85% in the examples) and a significant extension of cycle life (capacity retention of over 90% after 100 cycles, superior to all comparative examples).

[0055] Improved charge transport dynamics: The pioneering "overpass-style" ion-electron dual-channel design simultaneously overcomes the dual bottlenecks of low ionic and electronic conductivity in lithium-rich materials in solid-state systems. This enables the fabricated electrodes to exhibit superior rate performance in solid-state batteries, far exceeding that of single ion-conductor or electron-conductor coatings, making high-power output possible.

[0056] Enhanced interfacial contact and mechanical stability: The polymer components in the composite coating have a certain degree of flexibility, which can better buffer the volume change stress during the cold pressing (300-500 MPa) and long-term cycling of the battery, maintain the integrity of the coating, and form a closer contact with the solid electrolyte, which helps to reduce interfacial impedance.

[0057] The materials and processes exhibit strong versatility: This coating strategy is effectively compatible with various solid electrolyte systems, including sulfides, oxides, halides, and polymers, providing a universal and efficient platform solution for addressing the interfacial compatibility issues between lithium-rich materials and different solid electrolytes. Furthermore, the preparation method is based on wet chemistry, with mild conditions and controllable parameters, making it easy to achieve large-scale industrial production.

[0058] Excellent overall electrochemical performance: This invention successfully combines high capacity, high stability, and high rate performance. The resulting cathode material maintains high discharge capacity while also possessing high initial efficiency, long cycle life, and excellent rate capability, comprehensively surpassing uncoated and traditional single-coated lithium-rich materials, demonstrating its enormous application potential in next-generation high-energy-density solid-state batteries.

[0059] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Attached Figure Description

[0060] Figure 1 This is a SEM image of the Al / F co-doped lithium-rich manganese-based core material of Example 1 after coating.

[0061] Figure 2 The image shows the SEM image of the Al / F co-doped lithium-rich manganese-based core material in Example 1 before coating. Detailed Implementation

[0062] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0063] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0064] Example 1: Preparation of Al / F co-doped lithium-rich manganese-based cathode material with α-ZrP-PANI composite coating (2.0 wt%, mass ratio 5:1)

[0065] Step 1: Al / F co-doped lithium-rich manganese-based core material (Li 1.2 Ni 0.13 Co 0.12 Mn 0.54 Al 0.01 O 1.98 F 0.02 Preparation of )

[0066] This step employs the classic coprecipitation-high temperature solid-state sintering method.

[0067] Precursor preparation by coprecipitation:

[0068] Calculate and weigh the required amounts of nickel nitrate [Ni(NO3)2·6H2O], cobalt nitrate [Co(NO3)2·6H2O], manganese nitrate [Mn((NO3)2 50% aqueous solution] and aluminum nitrate [Al(NO3)3·9H2O] according to the metal ion molar ratio Ni:Co:Mn:Al=0.13:0.12:0.54:0.01, dissolve them in deionized water, and prepare a mixed salt solution with a total metal ion concentration of 2.0 mol / L.

[0069] A 4.0 mol / L sodium hydroxide (NaOH) solution was prepared as a precipitant, and a 0.5 mol / L ammonia (NH3·H2O) solution was prepared as a complexing agent.

[0070] The coprecipitation reaction was carried out in a 2L continuously stirred reactor (CSTR). First, a certain amount of deionized water and ammonia solution (maintaining a complexing agent concentration of ~0.1 mol / L) were added to the reactor, and the mixture was heated to 55°C in a water bath and maintained at a constant temperature. Stirring was then started, with the speed set to 600 rpm.

[0071] Simultaneously, two precision peristaltic pumps were used to pump the mixed salt solution and sodium hydroxide solution into the reaction vessel at constant flow rates. By monitoring and adjusting the pumping rate of the NaOH solution in real time, the pH value of the reaction system was precisely controlled to remain stable at 10.8 ± 0.1.

[0072] The reaction continued for 24 hours to ensure complete precipitation of the metal ions. After the reaction, the resulting suspension was allowed to stand for 6 hours, and then the precipitate was collected by vacuum filtration. The precipitate was repeatedly washed with deionized water until the filtrate was neutral (pH≈7), and then the filter cake was dried in a vacuum oven at 120°C for 12 hours to obtain Ni. 0.16 Co 0.15 Mn 0.68 Al 0.012 (OH)2 precursor powder.

[0073] High-temperature solid-state sintering and doping:

[0074] The dried precursor powder was uniformly mixed with a lithium source (lithium hydroxide LiOH·H2O) and a fluorine source (ammonium fluoride NH4F). The amount of LiOH·H2O was calculated and weighed based on a Li / (Ni+Co+Mn+Al) molar ratio of 1.55:1 (i.e., 5% lithium excess). The amount of NH4F was calculated and weighed based on 2 at% oxygen sites in the substitute material.

[0075] Place the mixture in an agate mortar, add an appropriate amount of anhydrous ethanol as a dispersion medium, and grind and mix thoroughly for 2 hours to ensure uniformity.

[0076] The well-mixed slurry was dried at 80°C to remove the ethanol, and then the powder was transferred to an alumina crucible.

[0077] The crucible was placed in a box furnace and sintered under a programmed temperature rise in an air atmosphere: first, the temperature was raised from room temperature to 500°C at a rate of 3°C / min, and pre-fired at this temperature for 5 hours to decompose hydroxides and nitrates; then, the temperature was raised to 900°C at a rate of 3°C / min, and held at this final temperature for 15 hours to crystallize.

[0078] After the sintering process is completed, the furnace is allowed to cool naturally to room temperature. The sintered block is then removed, ground, and sieved again (400 mesh) to obtain the Al / F co-doped lithium-rich manganese-based core material Li. 1.2 Ni 0.13 Co 0.12 Mn 0.54 Al 0.01 O 1.98 F 0.02 powder.

[0079] Step 2: Preparation of the α-ZrP-PANI composite coating layer

[0080] Preparation and purification of S1 and α-ZrP-PANI composite materials

[0081] Preparation of exfoliated α-ZrP nanosheet dispersion:

[0082] Weigh 0.5 g of crystalline α-ZrP powder and add it to 20 mL of a 0.5 mol / L tetrabutylammonium hydroxide (TBAOH) aqueous solution. The initial concentration of α-ZrP at this point is approximately 25 mg / mL.

[0083] The mixture was first stirred on a magnetic stirrer at 400 rpm at room temperature for 18 hours.

[0084] The mixture was then placed in an ultrasonic cell disruptor and sonicated for 1.5 hours at 500W power under ice-water bath cooling (working mode: 2 seconds of sonication followed by 2 seconds of intermittent sonication).

[0085] After sonication, approximately 25 mL of a homogeneous, semi-transparent, and distinctly Tyndall effect exfoliated α-ZrP nanosheet colloidal dispersion (α-ZrP concentration approximately 2.0 wt%) was obtained.

[0086] In-situ complexation and purification of α-ZrP-PANI:

[0087] Based on the above α-ZrP dispersion, accurately prepare 40 mL of solution (solid content of about 1.0 wt%, containing about 0.4 g of α-ZrP) and place it in a 250 mL three-necked flask.

[0088] Accurately pipette 80 μL of freshly distilled aniline monomer (density approximately 1.02 g / mL, mass approximately 0.0816 g) and slowly add it dropwise to the α-ZrP dispersion with stirring. At this point, the mass ratio of α-ZrP to aniline monomer is approximately 4.9:1 (close to 5:1).

[0089] The three-necked flask was placed in an ice-water bath at 0-5°C and stirred for 90 minutes to allow the aniline monomer to be fully adsorbed onto the surface and interlayer of the α-ZrP nanosheets.

[0090] Weigh 0.186 g of ammonium persulfate (APS) and dissolve it in 10 mL of pre-cooled 1.0 M hydrochloric acid solution to prepare an oxidizing agent solution. The molar ratio of this APS to aniline monomer is approximately 1.05:1.

[0091] Under continuous vigorous stirring and ice-water bath cooling, the hydrochloric acid solution of APS was slowly and dropwise added to the above mixture using a constant-pressure dropping funnel. The dropping time was controlled to be more than 45 minutes to ensure that the system temperature was maintained at 0-5℃ and the pH was controlled within 1-4. After the addition was completed, the reaction was continued in the ice-water bath for 10 hours. It can be observed that the color of the mixture gradually changed from colorless to light blue, and finally to dark green, indicating that aniline has been successfully polymerized on α-ZrP nanosheets to form a conductive emerald green imine salt, forming an α-ZrP-PANI composite material.

[0092] After the reaction is complete, the reaction mixture is immediately filtered, and the filter cake is washed alternately with large amounts of deionized water and anhydrous ethanol until the filtrate is colorless and transparent and neutral as measured by pH paper.

[0093] The filter cake was transferred to a vacuum drying oven and dried at 70°C for 12 hours to obtain a pure, powdered α-ZrP-PANI composite material.

[0094] S2. Construction of the composite coating layer

[0095] Preparation and coating process of composite coating agent dispersion:

[0096] Accurately weigh 0.040g of the α-ZrP-PANI composite material powder prepared in step S1 above (its mass accounts for 2.0% of the subsequent core material), disperse it in 40mL of anhydrous ethanol, and treat it in an ultrasonic bath (power 300 W) for 30 minutes to form a uniform composite coating agent dispersion.

[0097] Accurately weigh 2.0g of the Al / F co-doped lithium-rich manganese-based core material powder prepared in the first step, and slowly add it to the above composite coating agent dispersion.

[0098] The mixture was first dispersed by mechanical stirring at 600 rpm for 60 minutes, and then treated in an ultrasonic bath at 200 W for 15 minutes to ensure that the core material particles were uniformly dispersed and that the α-ZrP-PANI composite material could fully and uniformly coat the surface of the core material.

[0099] S3. Post-processing and crystallization of the product

[0100] The coated solid product was collected by vacuum filtration and washed twice with anhydrous ethanol to remove residual solvent.

[0101] The filter cake was transferred to a vacuum drying oven and dried at 90°C for 10 hours to obtain the coated precursor powder.

[0102] The dried powder was placed in a tube furnace and heated to 300°C at a programmed heating rate of 3°C / min under a continuous flow of high-purity argon gas (flow rate: 100 sccm), and then held at this temperature for 3 hours. This step aims to enhance the crystallinity, conductivity, and bonding strength of the coating layer to the core.

[0103] After heat treatment, the product was cooled to room temperature in the furnace, removed, and lightly ground to obtain the final Al / F co-doped lithium-rich manganese-based cathode material with α-ZrP-PANI composite coating (coating amount 2.0wt%, α-ZrP to PANI mass ratio 5:1).

[0104] Figures 1-2 The Al / F co-doped lithium-rich manganese-based core material Li in Example 1 of this invention 1.2 Ni 0.13 Co 0.12 Mn 0.54 Al 0.01 O 1.98 F 0.02 SEM images before and after coating, by Figure 1 and Figure 2 It can be seen that after coating, the lithium-rich manganese-based core ( Figure 1 The α-ZrP-PANI composite film forms a good three-dimensional conductive network on the surface, similar to an urban "overpass".

[0105] Step 3: Assembly and testing of solid-state batteries

[0106] Battery assembly:

[0107] All assembly steps were performed in an argon-protected glove box (H2O, O2 < 0.1 ppm).

[0108] First, take 80 mg of Li3InCl6 solid electrolyte powder, put it into a specific mold (12 mm in diameter), and pre-press it for 1 minute under a pressure of 300 MPa to form a dense electrolyte membrane layer.

[0109] A 12 mg composite cathode powder, consisting of the aforementioned α-ZrP-PANI composite-coated lithium-rich manganese-based cathode material, Li3InCl6 electrolyte, and conductive carbon in a mass ratio of 70:25:5, was ground in a grinder. The powder was then ground for 15 minutes in an agate mortar, uniformly coated onto one side of the LIC particles, and pressed onto the other side of the electrolyte membrane layer at a pressure of 300 MPa to 500 MPa.

[0110] A slightly smaller diameter lithium metal foil (150 μm thick) was placed on the other side of the Li3InCl6 particles as the negative electrode and pressed again at 10 MPa.

[0111] Finally, the inner liner of the solid-state battery mold is placed into the solid-state battery mold, and the screws are tightened with a pressure of 30MPa to seal it, thus obtaining a lithium-rich manganese-based all-solid-state battery.

[0112] Electrochemical testing:

[0113] The tests were conducted using the LAND battery testing system in a 25°C constant temperature chamber.

[0114] The charge / discharge test voltage range is 2.0 V to 4.8 V (vs. Li). + / Li).

[0115] The first charge / discharge cycle was at 0.1C (1C = 200mA g). -1 The experiment was conducted at a low magnification rate to fully activate the material.

[0116] Starting from the second cycle, constant current charge-discharge cycle tests were conducted at a rate of 0.1C, and the capacity and efficiency were recorded.

[0117] Example 2: α-ZrP-PANI composite coating (2.0 wt%, mass ratio 3:1)

[0118] Preparation process: exactly the same as step 2 of Example 1, except for the amount of aniline monomer added.

[0119] Parameter adjustment: Measure 40 mL of the same α-ZrP dispersion (containing approximately 0.4 g of α-ZrP). Then add 0.133 g of aniline monomer to adjust the mass ratio of α-ZrP to PANI to 3:1. The polymerization and post-treatment process is completely consistent with Example 1.

[0120] Example 3: α-ZrP-PANI composite coating (2.0 wt%, mass ratio 1:1)

[0121] Preparation process: exactly the same as step 2 of Example 1, except for the amount of aniline monomer added.

[0122] Parameter adjustment: Measure 40 mL of the same α-ZrP dispersion (containing approximately 0.4 g of α-ZrP). Then add 0.400 g of aniline monomer to adjust the mass ratio of α-ZrP to PANI to 1:1. The polymerization and post-treatment process is completely consistent with Example 1.

[0123] Example 4: α-ZrP-PANI composite coating (1.0 wt%, mass ratio 3:1)

[0124] Preparation process: basically the same as in Example 2, except that the amount of α-ZrP dispersion was changed.

[0125] Parameter adjustment: Measure 20 mL of the same α-ZrP dispersion (containing approximately 0.2 g of α-ZrP). Add 0.067 g of aniline monomer (maintaining α-ZrP:PANI = 3:1). The core material used remains 2.0 g. Therefore, the total coating weight is approximately 1.0 wt%. The polymerization and post-processing procedures are the same as in Example 1.

[0126] Example 5: α-ZrP-PANI composite coating (3.0 wt%, mass ratio 3:1)

[0127] Preparation process: basically the same as in Example 2, except that the amount of α-ZrP dispersion was changed.

[0128] Parameter adjustment: Measure 60 mL of the same α-ZrP dispersion (containing approximately 0.6 g of α-ZrP). Add 0.200 g of aniline monomer (maintaining α-ZrP:PANI = 3:1). The core material used remains 2.0 g. Therefore, the total coating weight is approximately 3.0 wt%. The polymerization and post-treatment processes are the same as in Example 1.

[0129] Comparative Example 1: Uncoated core material

[0130] Preparation process: The Al / F co-doped lithium-rich manganese-based core material prepared in the first step is used directly without any coating treatment.

[0131] Comparative Example 2: Al2O3 coating (2.0 wt%)

[0132] Preparation process: Urea-assisted hydrothermal method.

[0133] 2.0g of core material powder was evenly spread in the sample tray of the ALD reactor.

[0134] Trimethylaluminum (TMA) and water (H2O) were used as precursor sources, and the reaction temperature was set to 150°C.

[0135] By controlling the number of ALD cycles to 50, an amorphous Al2O3 coating layer with a thickness of about 2-3 nm and a mass percentage of about 2.0 wt% was deposited on the surface of the core material.

[0136] Comparative Example 3: Super P mixed coating (2.0 wt%)

[0137] Preparation process: Dry mechanical fusion was used.

[0138] Accurately weigh 2.0g of core material and 0.0408g of conductive carbon black (Super P).

[0139] Both were placed in a planetary ball mill and milled at 300 rpm for 2 hours to ensure that Super P was uniformly adhered to the surface of the core material particles.

[0140] Comparative Example 4: Single α-ZrP coating (2.0 wt%)

[0141] Preparation process: Similar to step 2 of Example 1, but without polymerization.

[0142] Take 40 mL of the same α-ZrP dispersion (containing approximately 0.4 g of α-ZrP), add 2.0 g of core material, and perform the same dispersion and wetting operations.

[0143] Subsequently, without adding aniline monomers and oxidants, the mixture was directly filtered, washed, and heat-treated at 300°C under an argon atmosphere for 3 hours to firmly coat α-ZrP onto the core surface.

[0144] Comparative Example 5: Single PANI coating (2.0 wt%)

[0145] Preparation process:

[0146] Preparation and coating process of composite coating agent dispersion:

[0147] Weigh 0.040g of pure polyaniline (PANI) powder (which accounts for 2.0% of the subsequent core material), disperse it in 40mL of anhydrous ethanol, and treat it in an ultrasonic bath (300W power) for 30 minutes to form a uniform PANI dispersion.

[0148] Accurately weigh 2.0g of the Al / F co-doped lithium-rich manganese-based core material powder prepared in the first step, and slowly add it to the above PANI dispersion.

[0149] The mixture was first dispersed by mechanical stirring at 600 rpm for 60 minutes, and then treated in an ultrasonic bath at 200 W for 15 minutes to ensure that the core material particles were uniformly dispersed and that PANI could fully and uniformly coat the surface of the core material.

[0150] Post-processing and crystallization of the product:

[0151] The coated solid product was collected by vacuum filtration and washed twice with anhydrous ethanol to remove residual solvent.

[0152] The filter cake was transferred to a vacuum drying oven and dried at 90°C for 10 hours to obtain the coated precursor powder.

[0153] The dried powder was placed in a tube furnace and heated to 300°C at a programmed heating rate of 3°C / min under a continuous flow of high-purity argon gas (flow rate: 100 sccm), and then held at this temperature for 3 hours. This step aims to improve the crystallinity, conductivity, and bonding strength of PANI to the core.

[0154] After heat treatment, the product is cooled to room temperature in the furnace, removed, and lightly ground to obtain the final Al / F co-doped lithium-rich manganese-based cathode material with a single PANI coating (coating amount 2.0wt%).

[0155] The test results of the solid-state batteries assembled in the examples and comparative examples are shown in Table 1.

[0156] Table 1 Electrochemical performance of all-solid-state batteries

[0157]

[0158] Results analysis:

[0159] 1. First-Loop Coulomb Efficiency (ICE) Analysis

[0160] The problem is evident: Comparative Example 1 (uncoated) has an extremely low ICE (57.63%), which typically reflects the irreversible lattice oxygen evolution and violent side reactions with the solid electrolyte during the first charge of the lithium-rich material, resulting in a severe loss of active lithium.

[0161] Coating effect: The ICE of all coated samples (Examples 1-5 and Comparative Examples 2-4) was significantly improved, proving that the coating layer can effectively suppress interfacial side reactions.

[0162] Synergistic Advantages: The α-ZrP-PANI composite coating of this invention exhibits superior performance. The ICE (Intensity Interval) of all embodiments is optimized to over 85%, with Example 2 (α-ZrP:PANI=3:1) achieving a first-cycle efficiency of 92.31%, reaching an industry-leading level. This far exceeds the comparative examples of single-component coatings (55%-78.69%), demonstrating a significant synergistic effect of the composite coating in terms of dense physical isolation and surface residual lithium neutralization, almost completely suppressing irreversible losses in the first cycle.

[0163] 2. Cyclic stability analysis

[0164] The superior stability of this invention: All embodiments of this invention (1-5) exhibited an ultra-high capacity retention of ≥92% after 100 cycles, significantly better than all comparative examples. This demonstrates the stable protective capability of the α-ZrP-PANI composite coating during long-term cycling. Example 2 (2.0%, 3:1) achieved the highest retention rate of 94%, demonstrating the best overall performance.

[0165] The shortcomings of a single coating layer: Comparative Examples 2 (Al2O3), 4 (α-ZrP), and 5 (PANI), while acting as ion conductors and providing some protection, exhibited significantly lower capacity retention (≤80%) compared to this invention. Their electronic insulation properties led to a continuous increase in electrode impedance during cycling. Comparative Example 3 (Super P) exhibited the worst cycling performance (58%), indicating that only electron channels accelerate interface deterioration, resulting in rapid battery failure.

[0166] The core value of composite coating: The excellent cycling performance (≥92%) of this invention directly verifies the core advantages of the "ion-electron" dual-channel structure. The electron network of PANI maintains charge balance, while α-ZrP provides stable ion channels and physical barriers, together constructing a long-term stable electrode-electrolyte interface.

[0167] 3. Ratio Performance Analysis

[0168] The power of the "overpass-style" dual-channel design: The rate performance (1C / 0.1C capacity ratio ≥92%) of this invention is generally superior to that of a single conductor coating. Example 2 (α-ZrP:PANI = 3:1) exhibits the best rate performance, reaching 96%, verifying that the optimized dual-channel ratio can significantly improve charge transport dynamics at high rates. Even with a thicker coating (Example 5, 3.0%), the 1C / 0.1C capacity ratio (95%) remains excellent, but fluctuates slightly compared to the optimal value (96%), and may slightly increase ion transport resistance.

[0169] Bottlenecks of single conductors: Comparative Example 4 (single α-ZrP) and Comparative Example 2 (Al2O3) have extremely poor rate performance (≤58.7%) due to the lack of electron channels. Although Comparative Example 3 (Super P) has electron channels, its rate performance (80.5%) is still inferior to that of the embodiments of the present invention due to the lack of effective ion transport pathways and interface protection.

[0170] Effect of coating amount: There is an optimal coating amount window for rate performance. Example 2 (2.0%) achieves the best balance between first-effect, cycling, and rate performance. A coating that is too thin (Example 4, 1.0%) may provide insufficient protection; a coating that is too thick (Example 5, 3.0%) may slightly increase ion transport resistance, resulting in a slight decrease in rate performance.

[0171] 4. Overall Performance and Optimal Solution

[0172] Example 2 (coating amount 2.0%, α-ZrP:PANI mass ratio 3:1) was determined to be the optimal solution. It achieved top-level performance in three key indicators: first-cycle efficiency (92.31%), cycle life (94% retention after 100 cycles), and rate performance (96% 1C / 0.1C ratio), achieving a relatively perfect performance balance.

[0173] This invention creates a novel smart coating layer with triple functions—highly efficient ion conduction, fast electron conduction, and strong isolation of side reactions—through molecular-level compositing of α-ZrP and PANI. The optimized data (initial efficiency >85%, best efficiency >92%; cycle retention >90%) fundamentally and effectively solves the interface stability and kinetic bottlenecks of lithium-rich manganese-based cathodes in solid-state batteries, paving the way for practical solid-state batteries with high energy density, high power, and long lifespan.

[0174] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. A lithium-rich manganese-based cathode material coated with an α-ZrP-conductive polymer composite, characterized in that, The material uses a bulk-modified lithium-rich manganese-based material as its core, and the surface of the core is coated with a composite coating layer of α-ZrP-conductive polymer. The conductive polymer is polyaniline or polypyrrole; The mass ratio of α-ZrP to the conductive polymer is 10:1 to 1:1; The total mass of the composite coating layer accounts for 0.5% to 5.0% of the mass of the core material; The preparation method of the α-ZrP-conductive polymer composite-coated lithium-rich manganese-based cathode material includes the following steps: (1) Preparation and purification of α-ZrP-conductive polymer composite material: The exfoliated α-ZrP nanosheet dispersion was mixed with conductive polymer monomers and subjected to in-situ polymerization under the action of an oxidant to generate α-ZrP-conductive polymer composite material; the obtained composite material was then separated, washed and dried to obtain powdered α-ZrP-conductive polymer composite material. (2) Construction of the composite coating layer: The powdered α-ZrP-conductive polymer composite material obtained in step (1) is redispersed in a solvent to form a composite coating agent dispersion; then the bulk-modified lithium-rich manganese-based core material is added to the dispersion, and the composite material is uniformly coated on the surface of the core material by mechanical stirring and ultrasonic treatment. (3) Post-processing and crystallization of the product: The coated material is separated, washed, dried, and subjected to low-temperature heat treatment in an inert atmosphere to obtain the final product.

2. The lithium-rich manganese-based cathode material coated with α-ZrP-conductive polymer composite according to claim 1, characterized in that, The bulk modification is element doping, and the general formula of the bulk-modified lithium-rich manganese-based material is xLi2MnO3·(1-x)LiTM 1-y M y O 2-z N z , where 0 < x < 1, 0.005 < y < 0.05, 0.001 < z < 0.05, TM is Ni, Co, and Mn, M and N represent doping elements, M is selected from one or more of Al, Ti, Zr, Ru, Mg, W, Mo, Nb, Y, Yb, Ce, Sn, and N is selected from one of F, Cl, S, P, B.

3. The lithium-rich manganese-based cathode material coated with α-ZrP-conductive polymer composite according to claim 2, characterized in that, The doping elements are Al / F co-doped or Mg / F co-doped.

4. The lithium-rich manganese-based cathode material coated with α-ZrP-conductive polymer composite according to claim 3, characterized in that, The doping element is Al / F co-doped.

5. A method for preparing a lithium-rich manganese-based cathode material with α-ZrP-conductive polymer composite coating as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation and purification of α-ZrP-conductive polymer composite materials: The exfoliated α-ZrP nanosheet dispersion was mixed with conductive polymer monomers and subjected to in-situ polymerization under the action of an oxidant to generate α-ZrP-conductive polymer composite material; the obtained composite material was then separated, washed and dried to obtain powdered α-ZrP-conductive polymer composite material. (2) Construction of the composite coating layer: The powdered α-ZrP-conductive polymer composite material obtained in step (1) is redispersed in a solvent to form a composite coating agent dispersion; then the bulk-modified lithium-rich manganese-based core material is added to the dispersion, and the composite material is uniformly coated on the surface of the core material by mechanical stirring and ultrasonic treatment. (3) Post-processing and crystallization of the product: The coated material is separated, washed, dried, and subjected to low-temperature heat treatment in an inert atmosphere to obtain the final product.

6. The preparation method according to claim 5, characterized in that, In step (1), the preparation method of the exfoliated α-ZrP nanosheet dispersion is as follows: crystalline α-ZrP powder is mixed with an intercalating agent aqueous solution, and after stirring and ultrasonic treatment, a stable exfoliated α-ZrP nanosheet colloidal dispersion is obtained; the intercalating agent is tetrabutylammonium hydroxide, and the concentration of its aqueous solution is 0.1mol / L~1.0mol / L; the initial concentration of the crystalline α-ZrP powder in the intercalating agent aqueous solution is 5mg / mL~50mg / mL; the stirring time is 6h~24h; the ultrasonic treatment power is 300W~600W, and the time is 0.5h~2h.

7. The preparation method according to claim 5, characterized in that, In step (1), the conductive polymer monomer is aniline or pyrrole; the mass ratio of the conductive polymer monomer to α-ZrP is 1:10 to 1:1; the oxidant is ammonium persulfate, and its molar ratio with the monomer is 0.5:1 to 1.5:1; the polymerization reaction is carried out in an ice-water bath at 0℃ to 5℃ for 6h to 12h, and the pH value of the reaction system is 1 to 4.

8. The preparation method according to claim 5, characterized in that, In step (2), the solvent is one or more of water, ethanol, isopropanol or N-methylpyrrolidone; the dispersion concentration of the α-ZrP-conductive polymer composite material in the solvent is 0.1 mg / mL to 5 mg / mL; The mechanical stirring speed is 500~800 rpm, and the time is 30~60 min; the ultrasonic treatment power is 150~300W, and the time is 5~15 min.

9. A solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the positive electrode comprises a lithium-rich manganese-based positive electrode material coated with an α-ZrP-conductive polymer composite as described in any one of claims 1-4, or an α-ZrP-conductive polymer composite-coated lithium-rich manganese-based positive electrode material prepared by the preparation method described in any one of claims 5-8.

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