17results about How to "Increase the diffusion coefficient" patented technology

This invention discloses a method and system for predicting the dissolution time of bubbles in oil-paper insulation, belonging to the field of electrical equipment insulation technology. The method includes: calculating the amount of various gases dissolved per unit volume of oil after the gas dissolution in oil reaches equilibrium; using 47℃ as a reference temperature, extrapolating this data to other temperatures and solubilities using the Arrhenius relation, and calculating the diffusion coefficients of various gases in oil at each temperature; calculating the diffusion coefficients of various gases in paper at each temperature; establishing a prediction model for the dissolution time of bubbles in oil-paper insulation, and calculating the dissolution time. This invention considers three factors—gas solubility in oil, diffusion coefficient in oil, and diffusion coefficient in paper—that vary with temperature and gas type, and calculates the dissolution time of a single stationary bubble in oil-paper insulation. This effectively reduces the risk of bubbles during transformer operation and can be widely applied to oil-paper insulation systems with the same kinetic description.

The application provides a positive electrode active material, a preparation method of the positive electrode active material and a potassium ion battery, and relates to the field of secondary batteries. The positive electrode active material comprises a core and a carbon layer covering the core, and the chemical formula of the core is K 3+x V 3‑x Ni x (PO4)4, 0.05<=x<=0.5. In the application, Ni 2+ is doped in the KVP material, so that the structural stability and the electrochemical performance of the positive electrode active material are effectively improved. Specifically, by doping Ni 2+ , the product purity and the crystalline integrity of the positive electrode active material are significantly improved, the structural stability of the product is enhanced, and the problems of low product purity and many impurities in the existing preparation method are solved. Moreover, the reaction kinetics and the cycle performance of the positive electrode active material are synergistically optimized.

The invention discloses a layered oxide positive electrode material of a sodium-ion battery and a preparation method of the layered oxide positive electrode material, and belongs to the technical field of batteries. The method comprises the following steps: preparing a NaNi < 0.33 > Mn < 0.33 > Fe < 0.33 > O2 precursor, mixing the precursor with a Na2S and P2S5 mixture under argon, carrying out heat treatment at 500 DEG C, and sintering with sodium hydroxide in an oxygen atmosphere at 800 DEG C to obtain the material. The core of the material is that a continuous super-ion conductor phase is formed on a grain boundary, a three-dimensional ion transmission network and a mechanical strengthening framework are constructed, the ion diffusion efficiency and the structural stability are remarkably improved, high-rate and long-cycle performance breakthrough is achieved, the process is controllable, and the industrialization potential is large.

The invention relates to the field of lithium batteries, and discloses a method for preparing lithium iron phosphate from waste lithium iron phosphate, which comprises the following steps: carrying out first sintering on waste lithium iron phosphate to obtain red powder I; detecting the contents of main elements and impurity elements in the red powder I; supplementing at least one of a lithium source, a phosphorus source, a titanium source and a vanadium source by taking the iron element as a reference according to a detection result; or detecting the contents of main elements and impurity elements in the waste lithium iron phosphate, supplementing the lithium source according to the detection result, sintering, and then supplementing at least one of the phosphorus source, the titanium source and the vanadium source; and finally, grinding, spray drying and sintering to obtain the lithium iron phosphate material. By accurately controlling the molar ratio of lithium, iron, titanium, vanadium and phosphorus, the lithium ion diffusion coefficient of lithium iron phosphate is improved from the atomic level, generation of magnetic foreign matters in the high-temperature sintering process of lithium iron phosphate crystals is inhibited, meanwhile, material particles are uniform, and the main phase purity is greatly improved.

The invention relates to the field of high polymer materials, in particular to composite resin and a preparation method and application thereof, and a gas separation membrane and a preparation method and application thereof. The composite resin comprises polyimide and a zeolite molecular sieve chemically bonded with amino groups on the surface. The polyimide composite resin provided by the invention is high in gas permeability coefficient and difficult to plasticize, and relieves the Trade-off effect to a certain extent. The method is especially suitable for preparation of gas separation membranes.

The invention discloses a ternary positive electrode material, a preparation method thereof and a lithium ion battery. The general formula of the ternary positive electrode material is LiNixCoyMnzM1-x-y-zO2, x is larger than or equal to 0.6 and smaller than 1, y is larger than 0 and smaller than or equal to 0.2, z is larger than 0 and smaller than or equal to 0.2, M is a doping element, and M is selected from one or more of Nb, W, Ta, Ti, Hf, Mo, La, Ce and Zr; the ternary positive electrode material is tested through an X-ray energy disperse spectroscopy (EDS), the molar percentage content of M tested under the energy of 10 keV is recorded as P1, the molar percentage content of M tested under the energy of 20 keV is recorded as P2, and the ternary positive electrode material meets the condition that P2 / P1 is larger than 0.2 and smaller than 0.9. According to the method, deep transition metal ion doping of the surface layer of the ternary material is achieved, in the circulation process, the deep doped ions play a stronger rivet role in the structure, and long-term circulation structural stability can be achieved.

This invention discloses a preparation method and application for improving the fast-charging performance of graphite composite materials. The preparation method involves mixing a graphite precursor with a catalyst and a conductive liquid, ball milling the mixture, followed by pre-carbonization, low-temperature graphitization, and acid washing to obtain a graphite precursor material. Then, the graphite precursor is mixed with a heteroatom polymer, a phosphorus compound, and an organotitanium compound, and heat-treated to obtain the graphite composite material. The graphite composite material prepared by this invention utilizes a catalyst to enhance the anisotropy of carbon during graphitization, and improves electronic conductivity through the conductive agent doped into the core. The titanium dioxide coating on the composite material's outer shell has the characteristics of large interlayer spacing, low expansion rate, and structural stability, which improves the lithium-ion insertion / extraction rate and rate performance. Since phosphorus itself has high specific capacity and a high voltage plateau, phosphorus doping improves the specific capacity and voltage plateau of the composite material, thus enhancing its fast-charging performance.

The invention belongs to the technical field of sodium ion batteries. The invention provides a sodium ion all-solid-state battery positive electrode preparation method, which comprises: S1, coating the surface of chromium-doped sodium nickel manganese oxide with a Na3Al2 (PO4) 3 and sodium dodecyl phosphate composite layer to obtain a modified chromium-doped sodium nickel manganese oxide material; s2, the modified chromium-doped sodium nickel manganese oxide material obtained in the S1, graphite, polyvinylidene fluoride and N-methyl pyrrolidone are mixed according to the mass ratio of 8: (1.4-1.6): (0.75-0.85): (3.8-4.2), and slurry is obtained; and S3, coating an aluminum foil with the slurry obtained in the step S2 to prepare a positive electrode plate, then drying the positive electrode plate, and punching the positive electrode plate into a circle to obtain the sodium ion all-solid-state battery positive electrode with the surface loading capacity of 5.4-6.2 mg / cm < 2 >. According to the invention, the capacity retention ratio of the sodium ion solid-state battery can be effectively improved.

The invention relates to a semi-solid alloying method for preparing a metal alloy material. The method comprises the following steps: firstly, obtaining a solid-liquid coexistence temperature interval suitable for treatment based on a phase diagram and thermodynamics calculation; then selecting metal raw materials forming the target component, and assembling the metal raw materials into an original blank with a close contact interface; and in the semi-solid temperature interval, a heat-force coupling process is adopted, a solid-liquid coexisting semi-solid structure is formed through local liquefaction induced by diffusion / mass transfer, and macroscopic flow mixing and microstructure reconstruction of the material are enhanced under the shear deformation or stirring effect, so that uniform alloying and structure refinement of the target alloy material are achieved. Compared with the prior art, the method has the advantages that uniform alloying and structure refinement of the alloy material can be realized under the condition that the traditional multi-step series connection of smelting, casting, heat treatment, deformation processing and the like is not needed, the alloy material with uniform components, fine matrix structure and uniformly distributed second phase is obtained, the process flow is simplified, and the energy consumption is low.

The invention belongs to the technical field of high-performance polymer materials and advanced micro-packaging, and relates to a hyperbranched polyimide embedding material as well as a preparation method and application thereof. The method comprises the following steps: dropwise adding a prepared hyperbranched polyimide solution with an active group as a terminal group into a functional material to be embedded, and carrying out suction filtration and drying to obtain embedded powder; the obtained embedding powder is placed in a supercritical carbon dioxide device, the hyperbranched polyimide embedding material generates a large number of pores by regulating and controlling the temperature, pressure and time and utilizing the swelling, plasticizing and extremely strong permeation and diffusion capabilities of supercritical carbon dioxide to hyperbranched polyimide with active groups, the specific surface area of the material is increased, and the hyperbranched polyimide embedding material is prepared. Finally, the composite material with a porous structure, high embedding rate and well protected activity of functional substances is obtained. According to the hyperbranched polyimide embedding material prepared by the method, the stability of functional substances can be improved, and the compatibility with an addition system can also be improved.

The invention belongs to the technical field of preparation of high-purity metal materials, and particularly relates to a preparation method and device of high-purity selenium. The preparation method of the high-purity selenium comprises the following steps: under a protective atmosphere, immersing a first crystallization rod and a flow baffle into a melt of a raw material selenium, then carrying out first-stage rotary crystallization, and taking out the first crystallization rod to obtain a first-stage crystallization product; and under the protective atmosphere, immersing a second crystallization rod and a flow baffle into the melt of the primary crystallization product, and then carrying out secondary rotary crystallization to obtain high-purity selenium of more than 6N on the second crystallization rod, the crystallization rate of the first-stage rotary crystallization is 0.1-0.5 mm / h, the crystallization rate of the second-stage rotary crystallization is 0.5-1.5 mm / h, and the thickness of a solid-liquid boundary layer is less than or equal to 50 microns. The flow baffle is added in the rotary crystallization process to strengthen convection of the melt, the thickness of a boundary layer of a solid-liquid interface is reduced, and impurity diffusion is accelerated; the crystallization rate is controlled to improve the crystallization efficiency, the product purity is improved through two times of crystallization, and the obtained product is high-purity selenium of more than 6N.

The application discloses a low-strain silicon-carbon negative electrode material and a preparation method thereof. The preparation method comprises the following steps: S100, synthesizing MgV2O6 products from a magnesium source and a vanadium source; S200, mixing porous carbon and the MgV2O6 products to obtain a base material; and S300, performing vapor deposition on the outer surface and the pores of the base material by using a silane gas source and a carbon gas source in an inert gas to obtain a silicon-carbon negative electrode material. The MgV2O6 with a stable crystal structure is prepared from the magnesium source and the vanadium source, and rigid support is provided in the subsequent preparation process, so that the use stability and the thermal stability are improved. The silane gas source and the carbon gas source are vapor-deposited on the base material to generate silicon-carbon active substances in situ, so that the silicon atoms, the carbon atoms and the carbon atoms on the surface of the base material form firm chemical bonds, the stress generated when the silicon expands is absorbed by the internal structure of the silicon-carbon negative electrode material, and thus the silicon-carbon negative electrode material with high use stability is prepared.

This invention belongs to the technical field of cathode materials for secondary batteries. More specifically, it relates to a doped lithium manganese iron phosphate material and its preparation method. The product of this invention includes a lithium manganese iron phosphate core and a lithium iron phosphate shell coating the surface of the lithium manganese iron phosphate core; wherein, the lithium manganese iron phosphate core includes pores and titanium dioxide deposited in the pores, the content of the titanium dioxide is 1.5-2.5% of the mass of the lithium manganese iron phosphate core, and the porosity of the lithium manganese iron phosphate is 20-25%; wherein, porosity = (1 - apparent density / true density) × 100%; the true density is 3.6 g·cm³. ‑3 The apparent density was measured using a tap density meter. The D50 of the lithium manganese iron phosphate core is 5-6 μm; and the Span value of the particle size distribution of the lithium manganese iron phosphate core is 0.8-1.0; the Span value = (D90-D10) / D50.

The invention provides a preparation method of a lithium-rich manganese-based composite positive electrode material coated with lithium ferric chloride and an application of a solid-state battery, a lithium ferric chloride coating layer is obtained in situ on the surface of the lithium-rich manganese-based positive electrode material through spray drying, and compared with a common coating layer, the lithium ferric chloride coating layer has the advantages that the coating layer is more uniform; the solid electrolyte has the advantages of good compatibility, excellent conductivity and ion conductivity and the like, and is a novel halide positive electrode material researched and developed for adapting to the solid electrolyte, so that the interface incompatibility between the positive electrode and the solid electrolyte is reduced. In addition, the excellent conductivity of lithium ferric chloride can reduce the use of a conductive agent on the positive electrode side, reduce ion and electron diffusion tortuosity and improve the diffusion coefficient. Meanwhile, the synthesis method is simple and effective, the cost is low, and the prepared composite positive electrode material can be used as an integrated all-solid-state positive electrode material and is suitable for large-scale production.

The invention provides a ternary positive electrode material and a preparation method thereof, a positive plate, a battery, a battery pack and electric equipment, the ternary positive electrode material comprises secondary particles DA, the secondary particles DA comprise a plurality of primary particles EA, and at least part of the primary particles EA in the secondary particles DA extend from the center of the secondary particles DA to the surface of the secondary particles DA; the exposed ratio of the (010) crystal face of the ternary positive electrode material is greater than or equal to 82%, and the ternary positive electrode material can improve the structural stability and the ionic conductivity of the ternary positive electrode material, and improve the electrochemical performance such as the rate and the cycling stability of the battery.

The invention relates to the technical field of lithium ion batteries, and discloses a composite coated ternary positive electrode material as well as a preparation method and application thereof. According to the composite coated ternary positive electrode material provided by the invention, the antimony element is doped in the matrix, so that the crystal structure can be stabilized by Sb < 5 + > with high valence and large ion radius, and the mixed arrangement of cations is reduced; the cobalt and lithium elements of the first coating layer can form a stable spinel structure on the surface of a matrix, and interface side reaction is inhibited; surface coating of the tungsten element, the aluminum element, the titanium element and the zirconium element inhibits interface side reaction, the structural stability of the positive electrode material is improved, and the cycling stability and the thermal stability of the lithium ion battery are further improved.

The application relates to a ni-doped sodium fluorophosphate and a preparation method and application thereof. According to the atomic molar ratio of each element in a chemical general formula, a sodium source, an iron source, a ni source, a phosphorus source and a fluorine source are weighed to obtain raw materials; the raw materials are ball milled to obtain mixed slurry and dried mixed powder after vacuum drying to remove the ball milling solvent; the dried mixed powder is pressed into a sheet and placed in a crucible, pre-sintering is carried out under inert gas protection, the precursor powder is obtained after being ground after being cooled to room temperature; a carbon source and a ball milling solvent are ball milled with the precursor powder, vacuum drying and tablet pressing are sequentially carried out to obtain a tablet; high-temperature sintering is carried out on the tablet under inert gas protection, the tablet is cooled to room temperature in the furnace after high-temperature sintering, and the ni-doped sodium fluorophosphate is obtained after being ground and crushed. The ni-doped sodium fluorophosphate has good positive electrode material electronic conductivity, high sodium ion diffusion coefficient, good cycle stability and good rate performance.