1213results about "Iron compounds" patented technology

The invention relates to a sodium ion battery, and belongs to sodium ion batteries. The battery cell of the sodium-ion battery comprises a positive plate, a negative plate and an electrolyte, the active material of the positive plate is carbon-coated aluminum-doped sodium ferric sulfate; the chemical formula of the aluminum-doped sodium ferric sulfate is Na < 2 + 2y > Fe < 2-x-y > Al < x > (SO4) 3, x is more than or equal to 0.01 and less than or equal to 0.05, and y is more than or equal to 0.1 and less than or equal to The particle size of the carbon-coated aluminum-doped sodium ferric sulfate ranges from 50 nm to 100 nm; the weight ratio of a carbon coating layer in the carbon-coated aluminum-doped sodium ferric sulfate is 1%-5%; the active material of the negative plate is carbon-coated sodium titanate; the specific surface area of the carbon-coated sodium titanate is 20 m < 2 > / g to 25 m < 2 > / g; the weight ratio of a carbon coating layer in the carbon-coated sodium titanate is 0.5%-3%. Volume expansion is jointly inhibited through structural stability of positive and negative electrode materials, and the cycle life is prolonged.

The invention discloses a high-stability layered oxide sodium-ion battery positive electrode material and a preparation method thereof.The high-stability layered oxide sodium-ion battery positive electrode material comprises a layered oxide matrix and a surface coating layer, a sodium source, a nickel source, a manganese source, a lithium source and a magnesium source are mixed according to the stoichiometric ratio, a pre-sintered product is heated to 850-950 DEG C at the speed of 0.5-2 DEG C / min to be calcined, and the high-stability layered oxide sodium-ion battery positive electrode material is obtained. The calcined product, lithium phosphate and aluminum nitrate are subjected to ball milling and mixing in a citric acid solution with the pH value of 3-5 according to the mass ratio of 1: (0.005-0.03): (0.002-0.02), and the capacity retention ratio of the battery is larger than or equal to 88% after 500 times of circulation under the voltage range of 2.0-4.0 V and the multiplying power of 0.5 C. The comprehensive protection from the bulk phase to the interface is realized by triple doping and gradient coating, and the cycle life is prolonged by two times. Interlayer spacing expansion and coating layer ion conduction cooperate to reduce polarization, and the applicable temperature range is widened to-30 DEG C to 60 DEG C. Seed crystal induction and segmented sintering ensure batch consistency, and the method is suitable for large-scale production. Cheap Fe / Mn is adopted to replace part of Ni, and the material cost is reduced by 40% compared with similar products.

A lithium manganese iron phosphate cathode material, including a first lithium manganese iron phosphate particle and a second lithium manganese iron phosphate particle. A molar ratio of Mn to Fe in the first lithium manganese iron phosphate particle is greater than or equal to 1. A molar ratio of Mn to Fe in the second lithium manganese iron phosphate particle is smaller than or equal to the molar ratio of Mn to Fe in the first lithium manganese iron phosphate particle. A particle size of the first lithium manganese iron phosphate particle is smaller than or equal to a particle size of the second lithium manganese iron phosphate particle. A preparation method of the lithium manganese iron phosphate cathode material and an application thereof are provided. The first precursor, having a manganese content greater than or equal to that of iron, inhibits crystal growth during sintering, resulting in a smaller particle size. The second precursor, having a manganese to iron ratio smaller than or equal to the ratio in the first precursor, promotes crystal growth during sintering, resulting in a larger particle size. This results in a particle size grading between large particles and small particles, improves the spatial utilization of particle packing, and enhances the compaction density and volumetric capacity of the lithium manganese iron phosphate cathode material.

The invention discloses a neodymium-zirconium co-substituted M-type strontium ferrite wave-absorbing material and a preparation method thereof, the chemical formula of the neodymium-zirconium co-substituted M-type strontium ferrite wave-absorbing material is Sr1-xNdxZr0. 2Fe11.8 O19, and x is more than or equal to 0.1 and less than or equal to 0.4. The method comprises the following steps: (1) mixing strontium nitrate, ferric nitrate nonahydrate, neodymium nitrate hexahydrate, zirconium nitrate pentahydrate, citric acid monohydrate and deionized water, stirring and dissolving to obtain sol; (2) adjusting the pH value of the sol to 6.5-7.5, and then heating to carry out sol-gel reaction to obtain wet gel; (3) drying and grinding the wet gel to obtain precursor powder; and (4) performing heat treatment on the precursor powder in a box-type furnace, cooling and grinding to obtain the neodymium-zirconium co-substituted M-type strontium ferrite wave-absorbing material. According to the material, effective wave-absorbing frequency band broadening is achieved, the matching thickness corresponding to the effective wave-absorbing bandwidth is as thin as 0.55-0.7 mm, and meanwhile, the performance requirements of thinness, width and strength in the field of electromagnetic compatibility are met.

The invention discloses a preparation method of a composite lithium-rich and lithium-supplement additive, which comprises the following steps: taking lithium ferrite as a core, preparing NiO (at) lithium salt by adopting an ALD atomic deposition method, fully and uniformly mixing carbon-coated lithium ferrite and the NiO (at) lithium salt, and sintering to prepare the composite lithium-rich and lithium-supplement additive. According to the invention, the advantages of high lithium supplement capacity of lithium ferrite, less gas production of lithium nickelate and good environmental adaptability are fully exerted, and the lithium supplement agent with high capacity and good stability is obtained; the nanometer nickel protoxide is in full contact with a lithium salt coating layer prepared by an ALD method, subsequent sintering is facilitated, preparation can be performed at a lower temperature, cost reduction is facilitated, meanwhile, the nickel protoxide and the peripheral lithium salt coating layer are subjected to a solid solution reaction, and residual lithium on the surface of lithium ferrite of a nuclear body can be obtained. The'two-channel lithium acquisition mode 'can reduce the overall residual alkali amount of the material, and is beneficial to improving the processing performance of subsequent battery slurry.

The application discloses a MnFe2O4 / GO wave-absorbing aerogel with a directional aperture structure and a preparation method thereof, belongs to the technical field of wave-absorbing material preparation, and is characterized in that manganese ferrite (MnFe2O4) magnetic particles are uniformly loaded on the surface of graphene to obtain a graphene aerogel with a three-dimensional loose porous structure and magnetic particle assembly; the MnFe2O4 is prepared by using a low-temperature co-precipitation method, and the MnFe2O4 / GO wave-absorbing aerogel is prepared by combining directional freezing and heat treatment, and the method is mild and simple. The application improves the impedance mismatch problem of the graphene material, enhances the magnetic loss of the material, and obtains a novel porous aerogel wave-absorbing material which has both dielectric loss and magnetic loss by introducing the manganese ferrite.

The invention relates to the technical field of lithium ion battery materials, in particular to a preparation method of a manganese iron carbonate precursor and a lithium manganese iron phosphate positive electrode material, which comprises the following steps: preparing a mixed salt solution from a bivalent manganese salt and a bivalent iron salt; adding pure water and the mixed salt solution into a first-stage reaction kettle, preparing a reaction base solution, and adding a first precipitator into the first-stage reaction kettle to obtain a first reaction product; enabling the first reaction product to flow into a second reaction kettle through overflow, and adding a second precipitator to obtain a second reaction product; and enabling the second reaction product to flow into a slurry transfer tank through overflow, washing and drying the second reaction product to obtain a manganese iron carbonate precursor, mixing a lithium source, a phosphorus source, a carbon source and the manganese iron carbonate precursor, and sintering to prepare the carbon-coated lithium iron manganese phosphate positive electrode material. The primary particle size of the prepared manganese iron carbonate precursor can be less than or equal to 200nm, and the rate capability and the cycling stability of a positive electrode material lithium ion battery finally prepared by sintering are improved.

The embodiment of the invention relates to a positive electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: putting a first lithium salt and a transition metal oxide into a zirconium oxide ball milling tank for wet milling to obtain a metal salt precursor; and performing heat treatment on the metal salt precursor in an inert atmosphere to obtain the lithium-rich cation disordered rock salt, placing the lithium-cation-rich disordered rock salt and a second lithium salt in a zirconium oxide ball milling tank for ball milling, so that a non-metallic element in the second lithium salt is inserted into a transition metal gap of the lithium-cation-rich disordered rock salt, thereby forming anions between an oxygen element and the non-metallic element of the lithium-cation-rich disordered rock salt, and obtaining a positive electrode material; wherein non-metallic elements in the second lithium salt are in a cation valence state, and the ion radius is smaller than the lithium ion radius in the first lithium salt and the transition metal ion radius in the transition metal oxide.

The invention discloses an ethanol-regulated layered metal oxide, a preparation method thereof and an application of the ethanol-regulated layered metal oxide in preparation of a single-walled carbon nanotube by catalytic cracking of methane, alkali liquor and soluble metal salt containing Fe, Mo, Mg and Al are dropwise added into an alkaline ethanol aqueous solution to form a precipitate, and the ethanol-regulated Fe-Mo / MgAl-LDOs catalyst is obtained after aging, drying and calcining. The catalyst is applied to methane catalytic cracking to prepare the single-walled carbon nanotube. According to the technical scheme, the dispersity of active components in the layered metal oxide is effectively improved, the layered metal oxide has larger specific surface area and pore diameter, but the pore volume is reduced, and the situation that growth of SWCNTs stops due to wall collision in the growth process is effectively avoided.

The invention belongs to the technical field of photocatalytic materials, and particularly relates to a manganese ferrite / bismuth tungstate heterojunction photocatalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: 1) dissolving sodium tungstate dihydrate, bismuth nitrate pentahydrate and hexadecyl trimethyl ammonium bromide in deionized water, and obtaining bismuth tungstate by using a hydrothermal method; 2) dissolving ferric chloride hexahydrate and manganese chloride tetrahydrate in water, then adding a sodium hydroxide solution, and obtaining manganese ferrite by using a hydrothermal method; and 3) dissolving bismuth tungstate and manganese ferrite into a sodium hydroxide solution, stirring, and drying to obtain the manganese ferrite / bismuth tungstate heterojunction photocatalyst. The formation of the heterojunction can greatly improve the activity of the manganese ferrite / bismuth tungstate in photocatalytic reduction of carbon dioxide.

The invention discloses an oxide-coated ion-doped sodium ferric sulfate positive electrode material as well as a preparation method and application thereof. The positive electrode material is formed by compounding a sodium ferric sulfate bulk phase material doped with various valence metal cations and anions and coated with carbon similar to a positive temperature coefficient thermosensitive metal oxide. Wherein the metal cations with various valence states are doped on Na or Na / Fe ion sites of the sodium ferric sulfate, the doped anions occupy part of three-dimensional S-O tetrahedron positions, the inorganic carbon in the carbon compound is uniformly distributed in the sodium ferric sulfate bulk phase material, and the organic carbon is uniformly distributed outside the sodium ferric sulfate bulk phase material. The positive electrode plate assembled battery prepared from the positive electrode material has the advantages of high reversible charge-discharge capacity, excellent cycle performance and rate capability and high electron and ion migration rate in a low-temperature environment. The method is low in raw material cost, simple in synthesis method, short in production period and suitable for large-scale continuous production.

The invention relates to the technical field of wave-absorbing materials, and particularly discloses a Zn-Fe-Mn oxide-hard carbon composite material and a preparation method and application thereof. The preparation method comprises the following steps: preparing pomegranate-shaped spheres through a coprecipitation-calcination method; then, uniformly dispersing the mixture in a self-made solvent composition, and curing and molding the mixture through heating treatment; and finally, carrying out annealing treatment in a high-temperature tube furnace at the temperature of 800 DEG C in an argon protective atmosphere (the flow rate is 100 sccm), so as to prepare the Zn-Fe-Mn oxide-hard carbon composite material. The composite material has a unique three-dimensional layered structure, shows excellent broadband microwave absorption characteristics, and can realize efficient electromagnetic wave attenuation. And a new way is opened up for structural design and optimization of the high-performance wave-absorbing material, and the wave-absorbing material has a wide application prospect in the application fields of advanced stealth technology and novel electromagnetic shielding.

The present application relates to the technical field of sodium‑ion batteries, and provides a sodium iron sulfate-based composite positive electrode material, and a preparation method therefor and a use thereof. The sodium iron sulfate-based composite positive electrode material has a porosity of 0.1%-10% and a compacted density of 2.1-3 g / cm3; in addition, the sodium iron sulfate-based composite positive electrode material has a specific surface area of 5-12 m2 / g, and a sodium-rich impurity phase in the sodium iron sulfate-based composite positive electrode material has a mass percentage content of 0.1%-1%. The present application helps to improve the performance of batteries, such as the charge / discharge capacity and the initial coulombic efficiency.

Provided is a magnetic powder having good high-frequency characteristics with low iron loss and good efficiency even at high frequencies. The present disclosure relates to an α-Fe-containing rare earth-iron-nitrogen-based magnetic powder, including: a core region containing a rare earth R, Fe, and N, where R represents at least one selected from the group consisting of Y, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, Lu, and Sm, and when R contains Sm, Sm constitutes less than 50 atm% of a total R content; and an α-Fe-containing region outside the core region, the α-Fe-containing region containing α-Fe and at least one selected from the group consisting of oxides, nitrides, and oxynitrides of the rare earth R.

The invention belongs to the technical field of electrochemistry, and particularly provides a lanthanum-cerium double-doped sodium ferric sulfate positive electrode material and a preparation method thereof. The material is composed of a matrix and a carbon coating layer coating the matrix, the matrix has a chemical expression of Na6Fe4-x-yLaxCey (SO4) 7, x is greater than or equal to 0.01 and less than or equal to 0.1, and y is greater than or equal to 0.01 and less than or equal to 0.1. The material is prepared through spray drying and high-temperature sintering treatment in sequence, the particle morphology is regular, and the particle size distribution is uniform; the electronic conductivity and Na < + > diffusion rate of the material are remarkably improved by rare earth doping, so that the material has more excellent low-temperature cycle performance, sodium storage performance and the like.

The invention discloses a sulfate-series sodium-ion battery positive electrode material with an expanded structure, a preparation method of the sulfate-series sodium-ion battery positive electrode material and a sodium-ion battery. The general formula of the sulfate-series sodium-ion battery positive electrode material is Na < 6-x > L < x > Fe < 5-y > M < y > (SO4) 8, wherein x is more than or equal to 0 and less than or equal to 0.5, y is more than 0 and less than or equal to 0.5, L is an alkali metal element with the same chemical valence as Na, and M is a transition metal element with the same chemical valence as Fe. According to the positive electrode material disclosed by the embodiment of the invention, the sodium ferric sulfate material with an expanded structure is taken as a main phase, and elements with variable radiuses are introduced into sodium sites and iron sites, so that the material further obtains a pore channel structure and defects with proper sizes, a three-dimensional diffusion channel of sodium ions is expanded, and the volume change in an electrochemical cycle process is inhibited; the structural stability of the material is ensured, so that the material shows relatively high gram volume and relatively good rate capability.

The invention discloses a lithium supplement agent which comprises a lithium supplement inner core and a carbon coating layer coating the surface of the lithium supplement inner core, and the lithium supplement inner core is doped with an Al element; the lithium supplementing agent meets the condition that A / I is larger than or equal to 0.3 and smaller than or equal to 4, A is the mass ratio of the Al element in the lithium supplementing agent, and I is the ID / IG value of the lithium supplementing agent in a Raman spectrogram. By regulating and controlling the A / I ratio of the Al doping amount to the carbon coating layer structure, the lithium supplementing capacity, the conductivity and the air stability are improved, and meanwhile, the gas production phenomenon in the lithium removal process is effectively inhibited.

The invention discloses an ardealite resource comprehensive utilization method and application thereof, and belongs to the technical field of ardealite resource utilization. The method comprises the following steps: S1, mixing ardealite and a reducing agent to obtain a mixture; s2, performing high-temperature decomposition treatment on the mixture in an inert atmosphere to obtain decomposed gas and a decomposed product; s3, sulfuric acid and / or carbon disulfide are / is prepared with the decomposition gas as the raw material, and the decomposition product is used for metallurgical steelmaking; according to the method, ferrous sulfide is used as a reducing agent, under the inert atmosphere, phosphogypsum is reduced into calcium oxide and calcium ferrite, generated sulfur dioxide tail gas is recycled, and comprehensive utilization of calcium and sulfur resources of phosphogypsum solid waste is achieved; the recycled sulfur dioxide can be used for preparing sulfuric acid and / or carbon disulfide, meanwhile, calcium oxide and calcium ferrite can serve as an adhesive and a slag former to be used for efficient metallurgical steelmaking, and the comprehensive utilization method for ardealite resources has a good application prospect.

A method for preparing a positive electrode material and an energy storage battery are provided. The method includes: preparing an Fe-MOF, including: dispersing a first iron source in a solvent, adding the cyanamide organic ligands into the solvent to perform reflux reaction to obtain a reaction solution, and performing cooling, filtering, and cleaning on the reaction solution to obtain the Fe-MOF; grinding and blending the Fe-MOF with a second iron source, a lithium source, and a phosphorus source to obtain a premix; and performing a sintering treatment on the premix under an atmosphere of an inert gas to obtain a composite lithium iron phosphate positive electrode material. The composite lithium iron phosphate positive electrode material includes lithium iron phosphate particles and carbon nanotubes, the lithium iron phosphate particles are attached to a surface of the carbon nanotubes, and there is iron wrapped by each of the carbon nanotubes.

The invention discloses a method for preparing a NaFeO2 material and leaching copper, zinc and molybdenum from copper slag, and relates to the technical field of metallurgical solid waste resource utilization. The method comprises the following steps: grinding the copper slag, mixing the ground copper slag with a sodium salt, roasting the mixture in a muffle furnace at a proper temperature, and finally carrying out ultrasonic washing and filtering on the roasted product to obtain filter residues and filtrate; and drying filter residues to obtain a high-purity NaFeO2 material, and recovering valuable metals such as copper, zinc and molybdenum from filtrate. In the washing process, valuable metal elements copper, zinc and molybdenum in the copper slag are efficiently leached into the solution, the leaching rate reaches 96% or above, and synchronous recovery of the valuable elements is achieved; according to the method, the industrial waste residue copper slag is successfully converted into the NaFeO2 product with the high additional value, meanwhile, valuable metal is efficiently extracted, the method has the advantages of being simple in process, low in cost, high in recycling degree and environmentally friendly, a new way is opened up for high-value utilization of the copper slag, and the method has good industrial application prospects.

The invention provides a multi-component composite metal oxide nanosheet gradient coating polypropylene diaphragm and a preparation method and application thereof, and the multi-component composite metal oxide nanosheet gradient coating polypropylene diaphragm comprises a polypropylene substrate and a Ti-Fe-Zr ternary composite oxide nanosheet gradient coating coated on the surface of the substrate, the thickness of the coating is 1-2.5 [mu] m, a gradient structure in which the concentration of nanosheets decreases progressively is formed from the surface to a substrate, the thickness of a surface compact layer accounts for 30-40%, and the interlayer spacing is 1.0-2.0 nm. The diaphragm disclosed by the invention has excellent electrolyte affinity, ionic conductivity and thermal stability, and can effectively inhibit the growth of lithium dendrites and prolong the cycle life of the battery.

The invention discloses a preparation method of a non-stoichiometric lithium supplement additive, a low-ratio non-stoichiometric base material is used as a core, an outer shell is a carbon-coated metal oxide layer, and the preparation method comprises the following steps: uniformly mixing iron oxide powder and a mixed lithium source, and carrying out uniform stirring to obtain a mixture; sintering, crushing and sieving the obtained blended powder in an inert gas atmosphere to obtain a lithium supplement additive base material A; and sufficiently and uniformly mixing the base material A and the carbon-coated improved oxide powder, and sintering to obtain a final product. The non-stoichiometric iron-based lithium supplement agent is synthesized, the intrinsic lithium preparation amount is greatly reduced, and part of low-cost lithium salt is mixed, so that the cost is effectively reduced, the residual alkali can be reduced, and the battery processing performance is improved; in addition, by adopting the carbon-coated metal oxide MxOy (at) C, conductivity improvement and an oxygen adsorption module are organically combined, the conductivity of the lithium supplementing agent is improved, the oxygen release amount is reduced, and the comprehensive performance of the lithium supplementing agent is obviously improved.

The invention provides an iron-based sulfate composite material as well as a preparation method and application thereof, and the method comprises the following steps: modifying aluminum-doped sodium ferrous sulfate Na < 2 + 2x > Fe < 2-x-1.5 y > Al < y > (SO4) 3 with few-walled carbon nanotubes subjected to surface acid treatment, and carrying out thermal shock reaction to obtain the iron-based sulfate composite material. The iron-based sulfate composite material provided by the invention can be used as a sodium ion battery positive electrode material with excellent rate capability and cycle performance.

The invention relates to the technical field of battery sodium supplementation agents, in particular to a sodium supplementation agent with a core-shell structure, a preparation method and a positive pole piece. The preparation method comprises the following steps: providing a core material containing sodium salt; a first coating process: providing a first coating material containing organic fluorine, mixing the core material containing the sodium salt with the first coating material, and performing first sintering to obtain a primary coating coated with a first coating layer; and a second coating process: providing a second coating material containing a carbon source, mixing the second coating material with the primary coating, and carrying out second sintering to obtain the sodium supplement which is coated with a first coating layer and a second coating layer and has the core-shell structure. The invention provides the sodium supplementing agent with the core-shell structure, the preparation method and the positive pole piece, so that the problem of poor sodium supplementing performance of the sodium supplementing agent in the related technology is solved.

A lithium iron phosphate / carbon / lithium-rich lithium iron oxide composite cathode material and a preparation method and an application thereof are provided. The preparation method includes the following steps: mixing iron salt, lithium compound, orthophosphate and an organic salt with water, to obtain a mixed slurry; performing a spray granulation on the mixed slurry, to obtain a precursor powder; and performing a heat preservation on the precursor powder in a protective atmosphere, to obtain a lithium iron phosphate / carbon / lithium-rich lithium iron oxide composite cathode material. The preparation method is based on the characteristics that electric double layer physical energy storage of porous carbon can enhance the rate, and lithium-rich lithium iron oxide additive can increase the system lithium source and prolong the service life, combined with the synthesis process of lithium iron phosphate and lithium-rich lithium iron oxide, a lithium iron phosphate / carbon / lithium-rich lithium iron oxide composite cathode material is synthesized by one-step method.

A ferrite powder comprising, as a main component compound, a magnetoplumbite-type hexagonal ferrite having a composition represented by the formula Sr(FexAlyZrz)12O19+δ (where x, y, z, and δ satisfy 0.400≤x<1.000, 0.030≤y≤0.350, 0.001≤z≤0.040, 0.750≤x+y+z<1.000, and -5.00≤δ≤-0.200), and having a volume resistance of 1.0×109 Ω·cm or less. A ferrite resin composite material, ferrite resin composite, and electromagnetic wave absorber containing said ferrite powder.

The invention discloses a method and a device for producing an efficient water treatment phosphorus removal agent by using red mud. The method comprises the following steps: drying the red mud and grinding into red mud powder; mixing and stirring the red mud powder and calcium oxide to obtain a mixture; calcining the mixture to obtain a calcium-iron composite oxide; mixing and stirring the calcium-iron composite oxide and a hydrochloric acid solution to obtain a mixed solution; and filtering the mixed solution to separate filter residues and filtrate, wherein the filtrate is the efficient water treatment phosphorus removal agent. The device comprises a tank body, a grinding chamber, a conveying and feeding chamber and a stirring chamber, the grinding chamber, the conveying and feeding chamber and the stirring chamber are sequentially arranged in the tank body from top to bottom, an automatic feeding mechanism is arranged at the top of the tank body, and a grinding mechanism, a spiral conveying and feeding mechanism and a stirring mechanism are arranged in the grinding chamber, the conveying and feeding chamber and the stirring chamber respectively. A discharge pipe and a feeding pipe are respectively arranged at the bottom and on the side wall of the tank body. The method has the advantages that red mud resources are recycled, and the efficient water treatment phosphorus removal agent is produced.

The present application belongs to the field of lithium battery technology, particularly relating to a preparation method for injected lithium manganese iron phosphate cathode material, electrodes, and lithium batteries. The method comprises: mixing, grinding, and drying lithium source, iron source, phosphorus source, and carbon source to obtain a lithium iron phosphate precursor; The lithium iron phosphate precursor is subjected to a first stage sintering and a second stage sintering in an inert gas atmosphere to obtain lithium iron phosphate material; The lithium iron phosphate material is processed into a flaky form, and manganese ions are implanted on both sides of the flaky lithium iron phosphate material in a preset vacuum degree environment to obtain lithium manganese iron phosphate cathode material.

The invention relates to the technical field of sodium ion battery positive electrode materials, in particular to a composite sodium ferric sulfate positive electrode material, a sodium ion battery and a preparation method. The preparation method comprises the following steps: preparing a group IIIA metal doped composite sodium ferric sulfate precursor; mixing with a solution containing a sodium source, an iron source and a phosphorus source; and performing staged heat treatment under a protective atmosphere to form a pyrophosphate ferric phosphate sodium coating layer. The particle size D50 of the composite sodium ferric sulfate positive electrode material is 3-5 [mu] m, and the composite sodium ferric sulfate positive electrode material can inhibit iron dissolution and enhance structural stability through bulk phase doping and surface coating cooperation, can prolong the cycle life of a battery and reduce gas production, and is suitable for a high-performance sodium ion battery.

Provided is a MnZn-based ferrite having excellent characteristics of maximum magnetic flux density (Bm) even in a high-temperature environment. The MnZn ferrite according to one embodiment of the present invention contains Fe2O3, ZnO, and MnO as main components, in 100 mol% of the main components, the content of Fe2O3 is 56.0 to 59.0 mol%, the content of ZnO is 2.5 to 7.0 mol%, and the remainder is MnO, and the MnZn ferrite contains 0.010 to 0.050 mass% of SiO2, 0.020 to 0.060 mass% of CaO, and 0.150 to 0.350 mass% of Co2O3 as auxiliary components relative to 100 mass% of the main components.