Preparation method and application of two-dimensional nano layered structure multi-metal phosphorus sulfide

Abstract

The invention relates to a preparation method of a two-dimensional nano layered polymetallic phosphorus sulfide, which comprises the following steps: mechanically and uniformly mixing a lithium-containing transition metal precursor and P2S5 in an inert atmosphere, then heating for melting and calcining, adding a crude product into an alcohol-water solution, heating and stirring, centrifugally separating, washing a precipitate, and drying to obtain the two-dimensional nano layered polymetallic phosphorus sulfide. The chemical formula of the polymetallic phosphorus sulfide is LixM1aM2bM3cM4dM5ePS3, x is greater than or equal to 0 and less than or equal to 0.86, and M1, M2, M3, M4 and M5 are independently selected from Co, Fe, Mn, Ni, Ti, Cu, Zn, Cd, Cr and Mo; a + b + c + d + e = 1, and a, b, c, d and e > = 0; wherein the transverse size of the two-dimensional nano layered multi-transition metal phosphorus sulfide is 0.5-10 [mu] m, and the thickness of the nanosheet is 10-40 nm. According to the invention, the two-dimensional phosphorus sulfide nano layered material can be rapidly prepared through the reaction of the transition metal precursor and phosphorus sulfide, and the two-dimensional phosphorus sulfide nano layered material shows good activity and stability when being used as a Li-O2 battery solid electrolyte.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-air batteries, and in particular relates to a preparation method and application of a two-dimensional nano-layered structured multi-metal phosphosulfide. Background Art

[0002] Amid the global push for energy conservation and emission reduction, the market for new energy vehicles and their associated energy storage industry is developing rapidly. The market for new energy vehicles, which primarily utilize batteries as their energy storage device, is expanding. Compared to traditional lead-acid batteries, lithium-ion batteries, as new energy batteries, offer high energy density, light weight, compact size, long cycle life, no memory effect, high economic benefits, and environmental friendliness. They are widely used in electronics, industry, agriculture, transportation, aerospace, and the military. Among these, lithium-ion batteries using lithium iron phosphate and lithium nickel cobalt manganese oxide as cathode materials offer significant technological advantages and are expected to dominate the battery market for a long time to come. Currently, the service life of lithium-ion batteries is typically 5-8 years. Since 2018, batteries for new energy vehicles released early into the market have begun to reach end-of-life. The rapid development of new energy batteries has generated a significant amount of waste lithium-ion batteries in recent years. The indiscriminate accumulation of these batteries not only wastes resources but also poses potential safety risks due to improper storage. The leakage of toxic and hazardous substances from the batteries can also cause serious environmental pollution. Directly dismantling and recycling these batteries would result in significant waste of resources and environmental pollution, and the high cost of power lithium batteries would remain unsolved. Therefore, it is crucial to harmlessly dispose of used lithium-ion batteries and fully recycle the metal materials they contain.

[0003] Lithium-air batteries have an ultra-high theoretical energy density (about 11680Wh·kg -1 ) is currently a hot topic in the research of new energy power batteries. However, phenomena such as combustion and explosion of organic electrolytes and generation of dendrites of lithium metal have caused lithium-air batteries to face serious safety issues. Replacing organic electrolytes with solid electrolytes can completely solve battery safety issues while achieving high energy density and high safety. In 2021, Professor Ren Wencai's team reported Cd / Mn vacancy-induced Li + and H + The rapid conduction in CdPS3 and MnPS3 enables ultrafast proton and lithium ion conduction, with lithium ion conductivity reaching 300-500 mS / cm at 30-60°C, demonstrating promising application potential as solid-state electrolytes. Recently, Professor M. Reyes Calvo fabricated air-stable devices based on transition metal phosphosulfides such as FePS3. These devices can operate in air for extended periods and exhibit excellent air-stability, laying the foundation for the use of phosphosulfides as air-stable solid-state electrolytes.

[0004] This project uses a simple experimental method to synthesize two-dimensional nano-layered multi-transition metal phosphosulfide using waste lithium-ion battery cathode materials as raw materials, and studies the 0.1 Mn 0.95 The application of PS3 as a solid electrolyte in lithium-air batteries provides new ideas and methods for the conversion and recycling of waste lithium-ion battery positive electrode materials and the preparation of cheap and efficient lithium-air battery solid electrolytes. It is expected to achieve large-scale recycling of waste lithium-ion battery positive electrode materials and promote the practical application of lithium-air batteries.

[0005] CN118507674A discloses a method for preparing cesium intercalated high entropy metal phosphosulfide fibers by a step-by-step synthesis method, comprising the following steps: (1) dissolving nitrate, sulfate or hydrochloride (Mn:Cd:Fe:Ni:Co=6:1:1:1:1) and hexamethylenetetramine (HMT) in a molar ratio of 1:(1.2-4) in deionized water, with the total metal salt concentration controlled at 0.02-0.2 mol / L, placing the mixture in a polytetrafluoroethylene-lined hydrothermal reactor, and heating the mixture at 110- The reaction was carried out at 160°C for 4-20 hours, and a high entropy metal hydroxide precursor was obtained after washing with deionized water and drying; (2) the above precursor was mixed with a phosphorus source (red phosphorus or phosphorus pentasulfide) and a sulfur source (sulfur powder or phosphorus pentasulfide) in a molar ratio of 1:1:(3-4), and the mixture was placed in a vacuum sealed quartz tube (vacuum degree 10-100 Pa), and the mixture was reacted at a high temperature of 450-650°C for 8-25 hours. The product was washed with CS2 and ethanol to remove residual sulfur, and a high entropy metal phosphosulfide Mn was obtained. 0.6 Cd 0.1 Fe 0.1 Ni 0.1 Co 0.1 PS3; (3) Mn 0.6 Cd 0.1 Fe 0.1 Ni 0.1 Co 0.1 PS3 was mixed with CsCl solution (concentration 0.2-8 mol / L, mass volume ratio 0.5-4 mg / mL), stirred at 25-85 ° C for 12-50 hours, filtered, washed and dried, and finally cesium intercalated high entropy metal phosphosulfide fiber Cs was obtained. 0.3 Mn 0.45 Cd 0.1 Fe 0.1 Ni 0.1 Co 0.1PS3. This method's multi-step synthesis process is complex, energy-intensive, and difficult to scale up. The high-temperature solid-phase reaction (450-650°C) and 70-hour total time significantly increase production costs. The hydrothermal reaction and vacuum sealing process face challenges in uniformity control and equipment limitations when scaling up. The multi-step solvent wash process further increases industrial environmental costs, hindering practical application.

[0006] CN116845340A discloses a method for preparing high entropy lithium-doped transition metal sulfur phosphide nanosheets (HE-Li) by high temperature sintering combined with ultrasonic exfoliation. x MPS3), the specific steps are: Fe, Co, Ni, Mn, Zn, P, S and LiCl are used as raw materials, mixed in a molar ratio of 0.2:0.2:0.2:0.2:1:3:1, ground under argon protection and vacuum sealed, and sintered at 750℃ for 72 hours to form a layered block; then the block is dispersed in an isopropanol / water mixed solvent and ultrasonically treated, the unpeeled part is removed by centrifugation and freeze-dried to finally obtain an ultrathin two-dimensional nanosheet. The characterization results show that SEM and TEM confirm that the block presents a single-layer sheet structure after peeling. HRTEM measures the (060) crystal plane spacing of 0.17nm and the interlayer spacing of 0.66nm, which is consistent with the theoretical model; ICP-OES and EDS show that Li and five transition metal elements (Fe, Co, Ni, Mn, Zn) are uniformly distributed without phase separation. XPS analysis further reveals that Li exists in a +1 valence state and the transition metals are in a mixed valence state (such as Fe 2+ / Fe 3+ 、Co 2+ / Co 3+ ), while P and S are stably bound as [P2S6]2- anions. However, this process is costly, primarily due to the high energy consumption of the long sintering time at 750°C, the cumbersome LiCl washing step, and the low yield of ultrasonic exfoliation. Further optimization is needed to reduce energy consumption and improve the efficiency of large-scale preparation.

[0007] CN118712377A discloses an amorphous five-element high-entropy metal phosphosulfide negative electrode material (FeCoNiZnMnPS3) for lithium-ion batteries and its preparation method. The synthesis process first involves polycondensing thiocyanate with a nitrogen-containing monomer (such as piperazine) in an aqueous solution to form a nitrogen-rich porous organic polymer. This polymer is then mixed with five transition metal salts (chlorides, nitrates, or acetates of Fe, Co, Ni, Zn, and Mn) and 2-methylimidazole in methanol. The mixture is dried and sintered at high temperature (500-800°C) to form a metal-doped precursor powder. Finally, in a dual-temperature reactor, the phosphorus and sulfur vapor released by the pyrolysis of red phosphorus / sublimed sulfur in the front zone reacts with the high-temperature (500-800°C) precursor in the rear zone to achieve phosphosulfurization, resulting in a nanoscale amorphous carbon-coated high-entropy material. This method uses the high entropy effect of the five metals in a nearly equimolar ratio to form a local electric field in the material to accelerate electron transfer. At the same time, the amorphous structure inhibits phase changes during the charge and discharge process, so that the material retains 71% of its capacity after 300 cycles at a current of 1.0A / g, and still maintains 72% of its capacity after 800 cycles at 3.0A / g. Its advantages lie in the environmentally friendly process, enhanced stability due to carbon coating, and performance improvements brought about by the high entropy synergistic effect. However, it faces challenges such as complex control of multi-metal ratios, high energy consumption of high-temperature processes, safety risks of red phosphorus / sulfur treatment, and difficulty in industrial scale-up. In the future, further optimization of process simplification and cost control are needed to promote practical applications. However, the above patent obtains the bulk phase of transition metal phosphosulfide. To obtain a two-dimensional transition metal sulfur phosphide, a complex exfoliation step is required, and the yield is low and it is unstable.

[0008] Another patent by the inventor discloses a method for preparing two-dimensional nano-layered transition metal phosphosulfide. The chemical formula of transition metal phosphosulfide is MPS3. Since its structure does not contain lithium ions and the single metal MPS3 structure has few vacancies, there is no position for lithium ion transition and lithium ion transmission channel. It can only be used as a positive electrode material catalyst and cannot be used as a solid electrolyte. Summary of the Invention

[0009] In order to solve the defects of the existing technology for preparing two-dimensional nano-layered multi-metal phosphosulfide, which is complicated, costly and inefficient. The present invention can quickly prepare two-dimensional phosphosulfide nano-layered materials by reacting transition metal precursors with phosphorus sulfide, and use them as solid electrolytes for Li-O2 batteries to show good activity and stability. Among them, the two-dimensional nano-layered multi-metal phosphosulfide materials prepared based on this synthesis strategy show high discharge specific capacity and excellent cycle performance when used as solid electrolytes in Li-O2 batteries. It is expected to become a type of cheap and efficient Li-O2 battery solid electrolyte and positive electrode catalyst, providing new ideas and methods for efficient lithium-air battery solid electrolytes.

[0010] Specifically, the present invention provides the following technical solutions to solve the above technical problems:

[0011] A method for preparing a two-dimensional nano-layered multimetallic phosphosulfide comprises the following steps: mechanically mixing a lithium-containing transition metal precursor and P2S5 in an inert atmosphere, then heating and melt-calcining the mixture, adding the crude product to an alcohol-water solution, heating and stirring the mixture, centrifuging the mixture, washing the precipitate, and drying the mixture to obtain a two-dimensional nano-layered multimetallic phosphosulfide. The chemical formula of the multimetallic phosphosulfide is Li x M1 a M2 b M3 c M4 d M5 e PS3, 0≤x≤0.86, M1, M2, M3, M4, M5 are independently selected from Co, Fe, Mn, Ni, Ti, Cu, Zn, Cd, Cr, Mo; a+b+c+d+e=1, and a, b, c, d, e≥0; wherein the lateral size of the two-dimensional nanolayered multi-transition metal phosphosulfide is 0.5-10μm, and the thickness of the nanosheet is 10-40nm.

[0012] Furthermore, the multi-transition metal phosphosulfide is Li 0.1 Mn 0.95 PS3, Li 0.05 Fe 0.975 PS3, Li 0.07 Co 0.965 PS3, Li 0.1 Zn 0.95 PS3, Li 0.2 Ni 0.72 Co 0.18 Mn 0.18 PS3, Li 0.1 Ni 0.57 Co 0.19 Mn 0.19 PS3, Li 0.1 Ni 0.475 Co 0.19 Mn 0.285 PS3, Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 PS3, Li 0.4 Ni 0.2 Mn 0.6 PS3

[0013] Furthermore, the lithium-containing transition metal precursor is a lithium-containing transition metal compound, wherein the transition metal element includes at least one of Co, Fe, Mn, Ni, Ti, Cu, Zn, Cd, Cr, and Mo, and the molar ratio of lithium to transition metal is 1:1 to 1.2:1.

[0014] Furthermore, the lithium-containing transition metal precursor is selected from LiCoO2, LiCoPO4, LiFePO4, LiMn2O4, LiCoMnO4, LiNi 0.5 Mn 1.5 O4、LiNi 0.85 Co 0.15 O2、Li x Ni 0.2 Co 0.3 Mn 0.5 O2、Li x Ni 0.1 Co 0.1 Mn 0.8 O2、Li x Ni 0.6 Co 0.2 Mn 0.2 O2、LiNi 0.9 Co 0.05 Mn 0.05 O2、LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2、LiNi 0.5 Co 0.5 O2、Li 1.2 Ni 0.2 Mn 0.6 O2、Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 At least one of O2.

[0015] Furthermore, the amounts of the lithium-containing transition metal precursor and P2S5 satisfy a molar ratio of Li to P2S5 of 1:2-10, preferably 1:2-5, and more preferably 1:2.5-3.

[0016] Furthermore, the inert atmosphere is nitrogen and / or argon; the method of mechanical mixing is not particularly limited, such as grinding, ball milling, ultrasound, and mechanical stirring.

[0017] Prior to calcination, the pretreatment step of mechanically mixing the lithium-containing transition metal precursor and P2S5 under an inert atmosphere is crucial and directly impacts the successful production of two-dimensional nanostructured products. P2S5 is sensitive to water and oxygen and easily deteriorates, forming hydrogen sulfide and phosphates, resulting in the loss of sulfur and phosphorus sources and the failure to produce multi-transition metal sulfide phosphides. Furthermore, P2S5 is highly toxic. Grinding in an argon-filled glove box ensures a stable and uniform mixing of P2S5 and the metal source, avoiding direct contact with air, water, and laboratory personnel.

[0018] Furthermore, the temperature is raised to 400-600° C. at a rate of 1-20° C. / min, preferably, the temperature is raised at a rate of 5-10° C. / min, and the calcination temperature is 400-480° C. The calcination time is 2-5 hours.

[0019] Furthermore, the alcohol aqueous solution is a mixed solvent of water and C1-4 alcohol in a volume ratio of 1-3:1-3. The C1-4 alcohol is selected from at least one of methanol, ethanol, propanol, butanol, butanediol, and propylene glycol. Preferably, the alcohol aqueous solution is a mixed solvent of water and ethanol in a volume ratio of 1-2:1-2. The heating and stirring is to raise the temperature to 50-90°C, preferably 60-70°C. The purpose of using the hot alcohol aqueous solution treatment is to remove unreacted P2S5 and by-products.

[0020] Furthermore, washing is performed with anhydrous ethanol for 1-5 times, such as 3-4 times; and drying is performed by vacuum drying.

[0021] The second object of the present invention is to provide a dual-functional application of the two-dimensional nano-layered multi-transition metal phosphosulfide as a solid electrolyte and a positive electrode catalyst in a Li-O2 battery.

[0022] The design of solid electrolytes for lithium-air batteries must take into account both ion transport properties and interface compatibility. The two-dimensional nano-layered multi-transition metal phosphosulfide synthesized by this method is synthesized by introducing different concentrations of Li + , which leads to the formation of abundant transition metal vacancies in the nanosheets. These vacancies act as active sites for lithium ion migration and react with Li + The synergistic effect produces a simultaneous improvement in the electronic and ionic conductivity of the material, thereby achieving a fast kinetic response, low diffusion energy barrier, and sufficient supply of reaction sites in the electrochemical process. The three-dimensional interconnected network formed by the interlayer van der Waals gap and the stacking of layers not only establishes a continuous lithium ion transmission channel, but also inhibits the formation of lithium dendrites and promotes Li + Uniform deposition and layered structure can effectively alleviate Li + Volume stress during transport. This combination of high ionic conductivity and interfacial adaptability enables this two-dimensional nanostructured multi-transition metal phosphosulfide, when used as a solid electrolyte, to maintain stable ion transport efficiency at high current densities while significantly slowing the rate of increase in interfacial impedance during cycling, ultimately demonstrating excellent overall performance.

[0023] On the other hand, when used as a positive electrode catalyst, the synthesized ultra-thin two-dimensional nano-multi-transition metal phosphosulfide containing lithium has a unique atomic-level thickness and high-density exposed transition metal active sites on the surface, which work synergistically with the unsaturated sulfur coordination center to efficiently catalyze oxygen reduction and oxygen evolution reactions, significantly reducing electrochemical polarization; the multi-level pore structure formed by the stacking of two-dimensional nanosheets provides sufficient accommodation space for the discharge product Li2O2, avoiding blockage of the reaction active sites, while shortening the lithium ion and electron transmission paths, improving the reaction kinetics, and ultimately achieving high specific capacity, low overpotential and long cycle life of lithium-air batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 1 is the XRD pattern of the two-dimensional nano-layered multi-transition metal phosphosulfide prepared in Examples 1 to 8.

[0025] Figure 2 The Li prepared in Example 1 0.1 Mn 0.95 PS3, Li prepared in Example 6 0.1 Ni 0.475 Co 0.19 Mn 0.285 PS3 and Li prepared in Example 4 0.2 Ni 0.72 Co 0.18 Mn 0.18 XPS full spectrum of PS3 sample and corresponding Li 1s spectrum.

[0026] Figure 3 Li obtained in Example 7 0.86 Mn 0.38 Ni 0.095 Co 0.095 PS3, Li prepared in Example 8 0.4 Ni 0.2 Mn 0.6 PS3 and Li prepared in Example 5 0.1 Ni 0.57 Co 0.19 Mn 0.19 SEM image of PS3 sample.

[0027] Figure 4 The Li prepared in Example 1 0.1 Mn 0.95 PS3, Li prepared in Example 8 0.4 Ni 0.2 Mn 0.6 PS3 and Li prepared in Example 7 0.86 Mn 0.38 Ni 0.095 Co 0.095AFM image of PS3 sample.

[0028] Figure 5 is the Li prepared in Example 1 0.1 Mn 0.95 Discharge curve of the organic-inorganic composite solid film prepared by cross-linking PS3 and nitrile rubber as a solid electrolyte in Li-O2 battery.

[0029] Figure 6 The Li prepared in Example 1 0.1 Mn 0.95 PS3, Li prepared in Example 8 0.4 Ni 0.2 Mn 0.6 PS3 and Li prepared in Example 7 0.86 Mn 0.38 Ni 0.095 Co 0.095 The discharge curve of PS3 sample as cathode catalyst in Li-O2 battery and Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 Cycling stability test results of PS3. DETAILED DESCRIPTION

[0030] The following specific embodiments further illustrate the technical solutions of the present invention.

[0031] The chemical formula of the product obtained in each example was determined by ICP testing.

[0032] Example 1

[0033] Weigh 10mmol LiMn2O4 and 30mmol P2S5, place them in a glove box protected by high-purity argon (O2 and H2O content are both ≤20ppm) and grind them mechanically at a speed of 200rpm for 10 minutes. After grinding, pass them through a 100-mesh sieve to remove larger-sized raw materials. Transfer the mixed raw materials to a covered corundum crucible, place them in a tube furnace protected by argon, heat them at 5℃ / min to 450℃ and hold them for 2h, and then cool them naturally to obtain Li 0.1 Mn 0.95 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.1 Mn 0.95 PS3 material.

[0034] Example 2

[0035] 10 mmol LiFePO4 and 30 mmol P2S5 were weighed and placed in a glove box protected by high-purity argon (O2 and H2O contents were both ≤ 20 ppm) for mechanical grinding and mixing. The mixed raw materials were transferred to a covered corundum crucible, placed in a tube furnace with argon protection, and heated to 420°C at 5°C / min and maintained for 2 hours. After natural cooling, Li 0.05 Fe 0.975 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.05 Fe 0.975 PS3 material.

[0036] Example 3

[0037] Weigh 10mmol LiCoO2 and 30mmol P2S5, place them in a glove box protected by high-purity argon (O2 and H2O content are both ≤20ppm) and grind them mechanically at a speed of 200rpm for 10 minutes. After grinding, pass through a 100-mesh sieve to remove larger raw materials. The mixed raw materials are transferred to a covered corundum crucible, placed in a tube furnace with argon protection, heated to 460℃ at 5℃ / min and maintained for 2h. After natural cooling, Li 0.07 Co 0.965 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.07 Co 0.965 PS3 material.

[0038] Example 4

[0039] Weigh 10mmol LiNi 0.8 Co 0.1 Mn 0.1O2 and 30mmol P2S5 were placed in a glove box protected by high-purity argon (O2 and H2O content were ≤20ppm) for mechanical grinding and mixing at a speed of 200rpm for 10 minutes. After grinding, the raw materials were passed through a 100-mesh sieve to remove larger raw materials. The mixed raw materials were transferred to a covered corundum crucible, placed in a tube furnace with argon protection, heated to 450℃ at 5℃ / min and maintained for 2h. Li was obtained after natural cooling. 0.2 Ni 0.72 Co 0.18 Mn 0.18 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.2 Ni 0.72 Co 0.18 Mn 0.18 PS3 material.

[0040] Example 5

[0041] Weigh 10mmol LiNi 0.6 Co 0.2 Mn 0.2 O2 and 30mmol P2S5 were placed in a glove box protected by high-purity argon (O2 and H2O content were ≤20ppm) for mechanical grinding and mixing at a speed of 200rpm for 10 minutes. After grinding, the raw materials were passed through a 100-mesh sieve to remove larger raw materials. The mixed raw materials were transferred to a covered corundum crucible, placed in a tube furnace with argon protection, heated to 460℃ at 5℃ / min and maintained for 2h. Li was obtained after natural cooling. 0.1 Ni 0.57 Co 0.19 Mn 0.19 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.1 Ni 0.57 Co 0.19 Mn 0.19 PS3 material.

[0042] Example 6

[0043] Weigh 10mmol LiNi 0.5 Co0.2 Mn 0.3 O2 and 30mmol P2S5 were placed in a glove box protected by high-purity argon (O2 and H2O content were ≤20ppm) for mechanical grinding and mixing at a speed of 200rpm for 10 minutes. After grinding, the raw materials were passed through a 100-mesh sieve to remove larger raw materials. The mixed raw materials were transferred to a covered corundum crucible, placed in a tube furnace with argon protection, heated to 480℃ at 5℃ / min and maintained for 2h. Li was obtained after natural cooling. 0.1 Ni 0.475 Co 0.19 Mn 0.285 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.1 Ni 0.475 Co 0.19 Mn 0.285 PS3 material.

[0044] Example 7

[0045] Weigh 10mmol Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2 and 30mmol P2S5 were placed in a glove box protected by high-purity argon (O2 and H2O content were ≤20ppm) for mechanical grinding and mixing at a speed of 200rpm for 10 minutes. After grinding, the raw materials were passed through a 100-mesh sieve to remove larger raw materials. The mixed raw materials were transferred to a covered corundum crucible, placed in a tube furnace with argon protection, heated to 480℃ at 5℃ / min and maintained for 2h. Li was obtained after natural cooling. 0.86 Mn 0.38 Ni 0.095 Co 0.095 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 PS3 material.

[0046] Example 8

[0047] Weigh 10mmol LiNi 0.5 Mn 1.5 O4 and 30mmol P2S5 were placed in a glove box protected by high-purity argon (O2 and H2O contents were both ≤20ppm) and mechanically ground at a speed of 200rpm for 10 minutes. After grinding, the raw materials were passed through a 100-mesh sieve to remove larger raw materials. The mixed raw materials were transferred to a covered corundum crucible, placed in a tube furnace with argon protection, heated to 480℃ at 5℃ / min and maintained for 2h. Li was obtained after natural cooling. 0.4 Ni 0.2 Mn 0.6 The crude PS3 product was placed in a water / ethanol mixture with a volume ratio of 1:1 and stirred at 70°C for 1 hour to dissolve and remove the unreacted P2S5 by-product. The precipitate was collected after centrifugation (8000 rpm, 10 minutes), washed three times with anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 1 hour to obtain high-purity two-dimensional nano-layered Li 0.4 Ni 0.2 Mn 0.6 PS3 material.

[0048] Comparative Example 1

[0049] According to the method described in Example 2 of patent CN116845340A, high entropy lithium doped transition metal sulfur phosphide (HE-Li x MPS3), but the resulting product is not a two-dimensional nanolayer, but a bulk phase. The specific steps are as follows: Fe, Co, Ni, Mn, Zn, P, S and LiCl are mixed in a molar ratio of 0.2:0.2:0.2:0.2:1:3:1, ground under argon protection and sealed in a quartz ampoule, and then sintered in a tube furnace at 750°C for 72 hours; after cooling to room temperature, the block is ground into powder and washed several times with deionized water, and then vacuum dried at 60°C for 10 hours. The obtained powder is HE-Li x The MPS3 blocks were then dispersed in an isopropanol / water mixed solvent, sonicated, centrifuged to remove the unpeeled portion, and freeze-dried to obtain nanosheets.

[0050] Comparative Example 2

[0051] CdPS3 was prepared according to the chemical vapor transport method described in Science (2020, 370, 596), but the obtained product was a bulk structure and required two-step ion exchange and further ultrasonic stripping to obtain Li-containing +Two-dimensional nanosheet structure. The specific steps are as follows: 938 mg of cadmium powder, 259 mg of red phosphorus block, 803 mg of sulfur flakes and 40 mg of iodine were mixed and vacuum sealed in a quartz ampoule; the sealed ampoule was placed in the middle of a tube furnace and kept at a constant temperature of 700 ° C for 5 days. After the ampoule was cooled to room temperature, the product was collected at the cold end and washed with ethanol to remove residual iodine, and finally CdPS3 crystals were obtained. LixCdPS3 nanosheets were prepared using CdPS3 crystals as raw materials by a two-step alkali metal ion intercalation exchange method: 100 mg of CdPS3 crystals were immersed in 10 mL of a mixed solution containing 1 M KCl, 2 M K2CO3 and 1 M EDTA, stirred at a constant temperature of 50 ° C for 3 hours, and the suspension was washed with deionized water to remove excess K + ions, obtain K 0.3 Cd 0.85 PS3; K after washing 0.3 Cd 0.85 10 mL of 1 M LiCl solution was added to PS3 and stirred at room temperature for 2 h to achieve K + Replacement with Li+; after washing with deionized water again, Li 0.3 Cd 0.85 PS3 was redispersed in water and ultrasonicated for 15 min to promote exfoliation, obtaining ultrathin Li 0.3 Cd 0.85 PS3 nanosheet structure. However, the yield of nanosheets obtained by ultrasonic exfoliation is low, and the nanosheets are relatively fragile and unstable.

[0052] Figure 1 The XRD patterns of the two-dimensional nano-layered multi-transition metal phosphosulfides prepared in Examples 1 to 8 are shown. 0.1 Mn 0.95 PS3, Li 0.05 Fe 0.975 PS3, Li 0.07 Co 0.965 PS3, Li 0.2 Ni 0.72 Co 0.18 Mn 0.18 PS3, Li 0.1 Ni 0.57 Co 0.19 Mn 0.19 PS3, Li 0.1 Ni 0.475 Co 0.19 Mn 0.285 PS3, Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 PS3, Li 0.4 Ni 0.2Mn 0.6 PS3. Among them, Figure 1 d is Li of Example 4-6 0.2 Ni 0.72 Co 0.18 Mn 0.18 PS3, Li 0.1 Ni 0.57 Co 0.19 Mn 0.19 PS3, Li 0.1 Ni 0.475 Co 0.19 Mn 0.285 PS3. Here with Li 0.1 Mn 0.95 Let’s take the PS3 sample as an example. For example, Figure 1 (a) is Li 0.1 Mn 0.95 The XRD pattern of PS3 shows a series of strong diffraction peaks at 13.68°, 29.78°, and 34.80°, which correspond to the (001), (-201), and (-202) crystal planes in the standard card PDF No. 78-0495, indicating that the sample synthesized by this method is pure phase. At the same time, from the information in the standard PDF card, it can be concluded that the sample belongs to the monoclinic system and the C2 / m(12) space group. The results of the overall XRD pattern prove that the series of samples synthesized by this method have high purity and excellent crystal structure, verifying the effectiveness and reliability of this method.

[0053] Figure 2 The Li prepared in Example 1 0.1 Mn 0.95 PS3, Li prepared in Example 6 0.1 Ni 0.475 Co 0.19 Mn 0.285 PS3 and Li prepared in Example 4 0.2 Ni 0.72 Co 0.18 Mn 0.18 The full XPS spectrum of PS3 sample and the corresponding Li 1s spectrum. Figure 2 As shown in (ab), the Li prepared in Example 1 0.1 Mn 0.95 The XPS test results of the PS3 sample revealed the presence of four elements, Mn, P, S and Li, on its surface as well as the chemical states of each element. Figure 2 (cd) shows that the Li synthesized in Example 6 0.1 Ni 0.475 Co 0.19 Mn 0.285There are six elements Ni, Co, Mn, P, S and Li on the surface of PS3. Figure 2 (ef) shows that the Li synthesized in Example 4 0.2 Ni 0.72 Co 0.18 Mn 0.18 The surface of PS3 contains six elements: Ni, Co, Mn, P, S, and Li. XPS characterization results once again demonstrate the successful preparation of lithium-containing two-dimensional multi-transition metal phosphosulfide nanomaterials and confirm the feasibility of this conversion method.

[0054] Figure 3 Li obtained in Example 7 0.86 Mn 0.38 Ni 0.095 Co 0.095 PS3, Li prepared in Example 8 0.4 Ni 0.2 Mn 0.6 PS3 and Li prepared in Example 5 0.1 Ni 0.57 Co 0.19 Mn 0.19 SEM photos of PS3 samples. As can be seen from Figures (ab), Example 7 prepared Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 The PS3 sample has an irregular layered structure with a lateral size distribution ranging from 500 nm to 10 μm. Figures (cd) show the Li 0.4 Ni 0.2 Mn 0.6 The overall morphology of the PS3 sample shows a large flake structure at a 5 μm scale, showing an obvious layered stacking structure. Figure (ef) shows the Li 0.1 Ni 0.57 Co 0.19 Mn 0.19 The microstructure of PS3 can be reduced to a sheet unit size of 200nm-4μm. The transition metal phosphosulfide materials synthesized by this method exhibit different layered and stacking characteristics in their microstructure, which may correspond to different electrochemical properties and ion diffusion characteristics.

[0055] Figure 4 The Li prepared in Example 1 0.1 Mn 0.95 PS3, Li prepared in Example 8 0.4 Ni 0.2 Mn 0.6 PS3 and Li prepared in Example 7 0.86 Mn 0.38 Ni0.095 Co 0.095 AFM photo of PS3 sample. From the corresponding height curve, it can be concluded that the Li 0.1 Mn 0.95 The thickness of PS3 nanosheets is 14.03 nm; the Li 0.4 Ni 0.2 Mn 0.6 The thickness of PS3 nanosheets is 33.18 nm; the Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 The PS3 nanosheets were 14.97 nm thick. Overall AFM analysis confirmed that the nanomaterials prepared by this method have controllable thickness and regular two-dimensional morphology, validating the effectiveness and reliability of this method in the preparation of two-dimensional layered materials.

[0056] Application Example 1

[0057] In order to evaluate the electrochemical performance of the two-dimensional nano-layered multi-transition metal phosphosulfide synthesized by this method as a solid electrolyte, we used the solution casting method to cast the Li prepared in Example 1. 0.1 Mn 0.95 PS3 was cross-linked with nitrile rubber to prepare an organic-inorganic composite solid membrane, which was then assembled into a solid-state Li-O2 battery. The steps for preparing the solid electrolyte membrane are as follows: 0.05g of LiTFSI was dissolved in a mixed solution of acetone and xylene, and 0.5g of NBR powder was slowly added to the mixed solution under stirring. 0.1 Mn 0.95PS3 was dispersed in the mixture; the mixture was then stirred at 50°C for 24 hours to obtain a uniform slurry, which was then dripped into a polytetrafluoroethylene petri dish, placed in a muffle furnace, and dried at 50°C for 12 hours to obtain a composite solid electrolyte membrane. The battery assembly steps are as follows: 19 mg of Ketjen black and 1 mg of carbon nanotubes were added to 1 mL N-methylpyrrolidone, dispersed evenly, and then 222.2 mg of 1% polyvinylidene fluoride solution by mass was added and stirred evenly to obtain a mixed slurry, which was then coated on the surface of carbon paper and dried in vacuum at 110°C (wherein, the 1% polyvinylidene fluoride solution by mass refers to a solution with polyvinylidene fluoride as solute, N-methylpyrrolidone as solvent, and a mass fraction of polyvinylidene fluoride of 1%); using the above-mentioned electrode as the positive electrode, the lithium sheet as the negative electrode, and the solid-state membrane prepared above as the electrolyte with a concentration of 1%. During assembly, the lithium sheet and the solid-state membrane were immersed in a 1 mol / L LiTFSI-TEGDME (lithium bistrifluoromethylsulfonyl imide-tetraethylene glycol dimethyl ether) solution and then taken out. In the glove box, the group was assembled in the order of negative electrode shell-gasket-lithium sheet-composite solid electrolyte membrane-positive electrode sheet-positive electrode shell to form a solid-state Li-O2 battery (wherein the positive electrode shell is a mesh structure that can be connected to the external gas).

[0058] The assembled solid-state Li-O2 battery was subjected to constant current charge and discharge tests in a high-purity oxygen atmosphere. The test system pressure was 1 atmosphere, the test system temperature was room temperature, the test system was a Newwell tester, the constant current charge and discharge voltage range was 2.0-4.5V, and the current was 0.02mA.

[0059] Figure 5 is the Li prepared in Example 1 0.1 Mn 0.95 The discharge curve test results of the organic-inorganic composite solid film prepared by cross-linking PS3 and nitrile rubber as a solid electrolyte in Li-O2 batteries. Figure 5 Shown Li 0.1 Mn 0.95 The PS3 / NBR composite solid film has a high discharge specific capacity of about 9290 mAh g -1 Based on the same process, the two-dimensional nanostructures obtained in Example 2, Example 3, Example 4 and Example 8 were composite solid-state membrane Li 0.05 Fe 0.975 PS3 / NBR、Li 0.07 Co 0.965 PS3 / NBR、Li 0.2 Ni 0.72 Co 0.18 Mn 0.18 PS3 / NBR and Li 0.4 Ni 0.2 Mn 0.6PS3 / NBR, the measured discharge specific capacities are 6800, 7560, 6350 and 8820 mAh g -1 This indicates that the two-dimensional nanolayered multi-transition metal phosphosulfide synthesized by this method has great application potential as a solid electrolyte in Li-O2 batteries.

[0060] Application Example 2

[0061] The two-dimensional nano-layered multi-transition metal phosphosulfide prepared in the example was used as a positive electrode catalyst to assemble a Li-O2 battery. The specific steps were as follows: 9 mg of Ketjen black and 1 mg of carbon nanotubes were added to 1 mL The obtained two-dimensional nano-layered multi-transition metal phosphosulfide was dispersed evenly in N-methylpyrrolidone, and then 10 mg of the prepared two-dimensional nano-layered multi-transition metal phosphosulfide and 222.2 mg of a 1% polyvinylidene fluoride solution by mass were added and stirred evenly to obtain a mixed slurry. The mixed slurry was then coated on the surface of the carbon paper and dried in vacuo at 110°C (wherein, the 1% polyvinylidene fluoride solution by mass refers to a solution with polyvinylidene fluoride as the solute, N-methylpyrrolidone as the solvent, and a polyvinylidene fluoride mass fraction of 1%). The above-mentioned electrode was used as the positive electrode, the lithium sheet was used as the negative electrode, and the LiTFSI-TEGDME (lithium bistrifluoromethylsulfonyl imide-tetraethylene glycol dimethyl ether) solution with a concentration of 1 mol / L was used as the electrolyte. The battery was assembled in the glove box in the order of negative electrode shell-gasket-lithium sheet-diaphragm (injected with electrolyte)-positive electrode sheet-positive electrode shell to form a Li-O2 battery (wherein the positive electrode shell is a mesh structure that can be connected to the external gas).

[0062] The assembled Li-O2 battery was subjected to constant current charge and discharge tests in a high-purity oxygen atmosphere. All current densities and specific capacities were calculated based on the mass of the loaded material. The test system pressure was 1 atmosphere, the test system temperature was room temperature, the test system was a Newwell tester, and the constant current charge and discharge voltage range was 2.0-4.5V. Among them, the unlimited capacity charge and discharge test and the limited capacity cycle test were both conducted at 250mA g -1 carried out at a current density of .

[0063] Figure 6 (a) is Li of Examples 1, 8, and 7 0.1 Mn 0.95 PS3, Li 0.4 Ni 0.2 Mn 0.6 PS3, Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 (a) Charge and discharge curves of PS3 electrode in Li-O2 battery (b, c) Cyclic stability test results. Experimentally prepared two-dimensional nano-Li 0.1 Mn 0.95PS3, Li 0.4 Ni 0.2 Mn 0.6 PS3, Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 When PS3 materials were used as electrodes, they showed 13900, 7343 and 4624 mAh g -1 High discharge specific capacity. Usually, for the stability test of the battery, it is necessary to perform multiple constant current charge and discharge cycles under limited capacity. Figure 6 (b) is Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 The battery cycle performance diagram when PS3 is used as Li-O2 electrode, (c) is the corresponding coulomb efficiency cycle number change diagram. It can be seen from the figure that Li 0.86 Mn 0.38 Ni 0.095 Co0 .095 The PS3 assembled battery has a limited discharge capacity of 500 mAh g in a high purity oxygen system. -1 Under the condition of , it can run stably for 500 cycles, and the coulomb efficiency can still maintain 100% during 500 cycles, showing excellent cycle performance.

[0064] The electrical performance data of Li-O2 batteries using two-dimensional nano-layered multi-transition metal phosphosulfide as cathode catalysts in different embodiments are listed in Table 1. The cycle stability test was conducted with a discharge capacity of 500 mAh g -1 Under such circumstances, the discharge capacity and coulombic efficiency still remain at 100% and can run stably for several cycles.

[0065] Table 1 Li-O2 battery electrical performance data

[0066]

[0067] Overall, the two-dimensional nanostructured layered multi-metal phosphorus-sulfur compound cathode catalyst demonstrated significant advantages in discharge capacity and overpotential regulation, while also demonstrating excellent durability across various cycle tests. The layered phosphorus-sulfur compound material, synthesized through component optimization, possesses highly efficient bifunctional catalytic properties, synergistically promoting the kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in lithium-oxygen batteries, providing an innovative direction for the development of cathode materials for next-generation high-energy-density lithium-oxygen batteries.

Claims

1. A method for preparing two-dimensional nano-layered multimetallic phosphosulfide, characterized in that: The following steps are involved: Under an inert atmosphere, the lithium-containing transition metal precursor and P2S5 are mechanically mixed uniformly, and then the temperature is raised for melt calcination. The crude product is added to an alcohol aqueous solution, heated and stirred, centrifuged, and the precipitate is washed and dried to obtain a two-dimensional nano-layered multimetallic phosphosulfide. The chemical formula of the multimetallic phosphosulfide is Li x M1 a M2 b M3 c M4 d M5 e PS3, 0<x≤0.86, M1, M2, M3, M4, M5 are independently selected from Co, Fe, Mn, Ni, Ti, Cu, Zn, Cd, Cr, Mo; a+b+c+d+e=1, and a, b, c, d, e≥0; wherein the lateral size of the two-dimensional nanolayered multi-transition metal phosphosulfide is 0.5-10μm, and the thickness of the nanosheet is 10-40nm.

2. The preparation method according to claim 1, characterized in that Multi-range metal sulfide Li 0.1 Mn 0.95 PS3, Li 0.05 Fe 0.975 PS3, Li 0.07 Co 0.965 PS3, Li 0.1 Zn 0.95 PS3, Li 0.2 Ni 0.72 Co 0.18 Mn 0.18 PS3, Li 0.1 Ni 0.57 Co 0.19 Mn 0.19 PS3, Li 0.1 Ni 0.475 Co 0.19 Mn 0.285 PS3, Li 0.86 Mn 0.38 Ni 0.095 Co 0.095 PS3, Li 0.4 Ni 0.2 Mn 0.6 PS3.

3. The preparation method according to claim 1, characterized in that The lithium-containing transition metal precursor is a lithium-containing transition metal compound, wherein the transition metal element includes at least one of Co, Fe, Mn, Ni, Ti, Cu, Zn, Cd, Cr, and Mo, and the molar ratio of lithium to transition metal is 1:1 to 1.2:

1.

4. The preparation method according to claim 1, characterized in that The lithium-containing transition metal precursor is selected from LiCoO2, LiCoPO4, LiFePO4, LiMn2O4, LiCoMnO4, LiNi 0.5 Mn 1.5 O4、LiNi 0.85 Co 0.15 O2、Li x Ni 0.2 Co 0.3 Mn 0.5 O2、Li x Ni 0.1 Co 0.1 Mn 0.8 O2、Li x Ni 0.6 Co 0.2 Mn 0.2 O2、LiNi 0.9 Co 0.05 Mn 0.05 O2、LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2、LiNi 0.5 Co 0.5 O2、Li 1.2 Ni 0.2 Mn 0.6 O2、Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 At least one of O2.

5. The preparation method according to claim 1, characterized in that The amounts of the lithium-containing transition metal precursor and P2S5 are such that the molar ratio of Li to P2S5 is 1:2-10, preferably 1:2-5, and more preferably 1:2.5-3.

6. The preparation method according to claim 1, characterized in that The inert atmosphere is nitrogen and / or argon. The temperature for melt calcination is increased at a rate of 1-20°C / min to 400-600°C, preferably at a rate of 5-10°C / min, and the calcination temperature is 400-480°C. The calcination time is 2-5 hours.

7. The preparation method according to claim 1, characterized in that The alcohol aqueous solution is a mixed solvent of water and C1-4 alcohol in a volume ratio of 1-3:1-3; the C1-4 alcohol is selected from at least one of methanol, ethanol, propanol, butanol, butanediol, and propylene glycol.

8. The preparation method according to claim 1, characterized in that The alcohol aqueous solution is a mixed solvent of water and ethanol in a volume ratio of 1-2:1-2; the heating and stirring is to be heated to 50-90°C, preferably 60-70°C.

9. Use of the two-dimensional nano-layered multi-transition metal phosphosulfide according to any one of claims 1 to 8 as a solid electrolyte or cathode catalyst in a Li-O2 battery.

Images