312 results about "Ferromanganese" patented technology

The invention discloses a process for separating and recycling scandium, manganese and iron in iron-manganese slag, and belongs to the technical field of metallurgical engineering and comprehensive utilization of secondary resources. The method comprises the following steps: crushing the iron and manganese slag, mixing the crushed iron and manganese slag with a chlorinating agent and a molten salt medium, and carrying out chlorination reaction at 600-850 DEG C, so that iron and manganese are converted into chlorides to volatilize, and scandium is enriched in the slag; the volatile gas is subjected to multi-stage gradient condensation, and manganese and iron concentrates are respectively recovered in different temperature intervals; and leaching-extracting the chlorination residues to obtain a scandium-rich substance. According to the method, source separation and collaborative recovery of iron, manganese and scandium are achieved through pyrogenic process chlorination-condensation, the problems that in a traditional wet process, metal interferes with one another, the process is long, and pollution is heavy are solved, and the method has the advantages of being short in process, small in pollution and high in recycling degree.

The invention provides an amorphous carbon coated lithium manganese iron phosphate positive electrode material and a preparation method and application thereof, the preparation method comprises the following steps: mixing a lithium source, a ferrous source, a manganese source, a phosphorus source, a carbon source and a solvent to obtain mixed slurry; carrying out spray drying treatment on the mixed slurry, and carrying out plasma treatment on the obtained dried material to obtain a precursor material; and mixing the precursor material with a boron source, and sintering to obtain the amorphous carbon coated lithium iron manganese phosphate positive electrode material. The surface of the lithium manganese iron phosphate positive electrode material is coated with the amorphous carbon layer, the bonding strength of the amorphous carbon coating layer and the positive electrode material is high, the problem of electronic conductivity of the lithium manganese iron phosphate positive electrode material is solved, and meanwhile, the ionic conductivity of the material is improved through boron doping.

The invention discloses a cerium-zirconium-based high-entropy oxide as well as a preparation method and application thereof. According to the cerium-zirconium-based high-entropy oxide, cerium and zirconium serve as main bodies, and meanwhile rare earth elements (lanthanum, praseodymium, neodymium and samarium) and transition metal elements (manganese, iron, cobalt, nickel, copper and zinc) are introduced to form a high-entropy solid solution with the equal molar ratio and containing 3-8 kinds of metal. In the cerium-zirconium-based high-entropy oxide, the cerium element and the zirconium element respectively account for 20%-40% of the total amount, and the other elements are respectively 10%-30% in an equimolar ratio. The cerium-zirconium-based high-entropy oxide catalyst prepared by the invention has excellent oxygen storage and release capacity and CO oxidation capacity, and the CO complete conversion temperature is 181 DEG C. The method adopts a simple coprecipitation process, is mild in condition and low in cost, and is suitable for large-scale application in the field of tail gas purification.

The invention relates to the technical field of metal casting, and discloses a smelting and casting method of a high-toughness regenerated aluminum alloy, which comprises the following steps: measuring the iron content of a regenerated aluminum melt, regulating and controlling the manganese-iron ratio, heating the melt to 750-790 DEG C, and carrying out overheating treatment to eliminate a hereditary core; cooling to 630-645 DEG C, applying a mechanical shear flow field with the average shear rate not lower than 60s <-1 > in the interval, stripping a diffusion boundary layer on the surface of the iron-rich phase crystal nucleus by utilizing fluid drag force, breaking dendritic crystals, and separating out in a polyhedral or spherical manner; according to the method, through active intervention of a critical shear flow field, the problem of needle-like growth of an iron-rich phase caused by solute diffusion blocking in a traditional technology is solved, in-situ generation of the harmless iron-rich phase in the high-iron-content secondary aluminum is achieved, the obdurability of a die casting is improved, and dependence on the purity of raw materials is reduced.

The invention provides a preparation method of a ferromanganese phosphate precursor and a lithium ferromanganese phosphate positive electrode material, and the preparation method of the ferromanganese phosphate precursor comprises the following steps: S1, sequentially crushing, grinding and screening a ferromanganese alloy to obtain ferromanganese alloy powder; s2, the ferromanganese alloy powder is roasted and crushed in the oxygen atmosphere in sequence, and ferromanganese oxide powder is obtained; and S3, mixing the ferromanganese oxide powder and a phosphoric acid solution, carrying out a hydrothermal reaction, drying, dehydrating, and crushing to obtain the ferromanganese phosphate precursor. The ferromanganese phosphate precursor is prepared from the ferromanganese alloy, additional manganese source and iron source compounds do not need to be introduced, the product uniformity and stability are good, and the cost is lower. According to the invention, the atomic-level uniform dispersion of manganese and iron elements in the ferromanganese precursor is realized, the problem of dissolution of manganese is avoided, and the structural stability and electrochemical performance of the material are improved. The method is easy to industrialize.

The utility model relates to the technical field of chemical production, in particular to lithium manganese iron composite salt production equipment which comprises a supporting shell, the feeding hopper is arranged on the outer side of the top end of the supporting shell and connected with the supporting shell through a connecting frame; the discharging pipe is fixedly connected to the outer side of the bottom end of the supporting shell; the supporting assembly is arranged on the outer side of the discharging pipe and connected with the supporting shell; the reaction mechanism is arranged on the inner side of the supporting shell and is connected with the supporting shell; wherein the reaction mechanism comprises material storage assemblies, overturning assemblies and stirring assemblies, the material storage assemblies are arranged on the inner side of the supporting shell in a central symmetry mode and connected with the inner wall of the supporting shell through the overturning assemblies, the stirring assemblies are arranged on the inner sides of the material storage assemblies, and the stirring assemblies are connected with the material storage assemblies. Multiple stirring of raw materials can be realized, continuous production of ferrous sulfate reaction liquid can be realized, and the production efficiency is greatly improved.

The application discloses a high-carbon ferromanganese iron powder remelting process, which comprises the following steps: step one, pickling: high-carbon ferromanganese iron powder is subjected to pickling under the action of a pickling solution, so that a surface oxide layer is removed, and deoxidized ferromanganese iron powder is obtained; and step two, ultrasonic cleaning: the deoxidized ferromanganese iron powder obtained in step one is added into an ultrasonic cleaning machine for cleaning, so that surface stains and grease are removed. After preheating and degassing, nitrogen and oxygen of the ferromanganese sintered block are detected, and ingredients are prepared according to the nitrogen content, so that the ingredient amount is more reasonable, and the quality of the high-carbon ferromanganese alloy is improved. Moreover, the deoxidized skin of the high-carbon ferromanganese iron powder is removed outside the furnace, so that the deoxidized skin does not need to be removed by using a lossy reagent covering agent in the furnace, the alloy is less damaged, and the ferromanganese burning loss is reduced. As a result, the formed manganese oxide slag is less, the quality of the high-carbon ferromanganese finished product is greatly improved based on the above two points, the chemical composition of the high-carbon ferromanganese finished product is uniform, and the prepared high-carbon ferromanganese alloy has higher hardness and toughness.

The invention provides a preparation method of a high-wear-resistance alloy lining plate, and relates to the technical field of wear-resistance alloys, carbon steel and pig iron are mixed, heated and melted, high-carbon ferromanganese, medium-carbon ferrochrome and ferrosilicon are added, heating refining is carried out, aluminum powder is added, the mixture is put into a mold, cooling and demolding are carried out, heating homogenization, quenching and cooling are carried out, and a mother plate is prepared; mixing bismaleimide, the composite powder and sepiolite fibers, heating and stirring, coating a mother board with the mixture, firstly applying negative pressure, then applying positive pressure, heating and cooling to obtain a substrate layer; and placing the mother board in magnetron sputtering equipment, sputtering on the substrate layer to obtain a chromium nitride functional layer, and cooling to obtain the high-wear-resistance alloy lining board. The composite powder is prepared by mixing and heating chromium carbide powder and a hydrogen peroxide solution, filtering, mixing with an ethanol solution and gamma-aminopropyltriethoxysilane, heating, condensing and refluxing, washing and drying, and mixing and heating with amine-terminated polyether and N, N-dimethylformamide. The wear-resistant stability of the alloy lining plate can be improved.

The application relates to the field of wastewater treatment catalysis, and discloses a Fe-Cu-Mn ternary hydrotalcite-like catalyst and a preparation method thereof, which comprises iron, copper and manganese; the iron, copper and manganese are distributed in the layer plate metal central site in an atomic dispersion mode; the layer plate oxygen octahedron is in a non-symmetrical stretching distortion state; a 3.2-4.8 degree deviation is generated in the manganese oxygen copper bond angle in the layer plate; the lattice parameter a of the layer plate 110 crystal face direction is 0.305-0.312 nm; the molar ratio of copper to manganese is 1:2-1:5; and the molar sum of copper and manganese to the molar ratio of iron is 2:1-4:1. According to the application, the lattice non-symmetrical distortion induces the space overlap of the auxiliary metal and the iron active center orbit, an electron transfer path is constructed, the shielding effect of the hydroxyl ion on the iron active site under the alkaline environment is eliminated, the catalytic site activity is maintained, and stable and efficient catalytic treatment under wide pH working conditions is realized.

This invention relates to the field of ferroalloy smelting technology and discloses a high-carbon ferromanganese and its preparation method, comprising the following steps: raw material pretreatment; converter preheating and bottom material laying: pretreated high-grade manganese ore, lime, and coke powder are mixed and added as bottom material to the CLU converter for preheating; iron addition and initial reduction: high-carbon ferromanganese is added to the converter, and graphite fragments are added, and initial reduction is carried out under a pure argon atmosphere; atmosphere control and second-stage reduction: when the carbon content of the molten iron drops to 5.0-5.8%, the reblowing gas is switched to a mixed gas of argon, CO, and CH4, and the remaining high-grade manganese ore, silicon carbide, ferrosilicon manganese alloy, and supplementary coke powder are added in batches, while adjusting the slag composition; endpoint judgment and iron tapping. The high-carbon ferromanganese of this invention has precise composition and high purity, and the preparation method is characterized by high efficiency, low consumption, greenness, and high manganese recovery rate, enabling the industrial-scale production of high-carbon ferromanganese.

An active material for a positive electrode comprises tertiary particles (3). Each of the tertiary particles (3) comprises secondary particles (2). Each of the secondary particles (2) comprises primary particles (1). Each of the primary particles (1) comprises lithium manganese iron phosphate.

The invention provides a step-by-step coated lithium manganese iron phosphate material and a preparation method thereof. The method comprises the following steps: mixing a lithium source, an iron source, a manganese source and a phosphorus source with a first coating agent for morphology optimization and a carbon source, and carrying out wet processing and first sintering to obtain a precursor; and mixing the precursor with a second coating agent for interface strengthening and a carbon source, and carrying out secondary wet treatment and secondary sintering to obtain the final material. According to the method, the compaction density and the electrochemical capacity of the material are synergistically improved through a functional step-by-step coating strategy of morphology and interface in sequence, the technical contradiction that the compaction density and the capacity in the lithium manganese iron phosphate material are difficult to synergistically improve is effectively solved, and the method is controllable in process and suitable for preparation of the high-energy-density lithium ion battery positive electrode material.

The application discloses a method and system for recycling dust removal ash of blast furnace manganese iron smelting, and first proposes a technical route for recycling carbon powder, fluorite, manganese fluoride, manganese sulfate, potassium bicarbonate, potassium sulfate, sodium chloride and other valuable resources by water washing of the dust removal ash of blast furnace manganese iron smelting. The water washing slag and washing wastewater of the dust removal ash of blast furnace manganese iron smelting are simultaneously treated in a cooperative manner, the process can be designed according to the characteristics of the washing wastewater and the water washing slag, the multistage recovery of the valuable resources is realized, new impurities are not introduced, and the added value of the recovered resources is improved. In addition, the whole process does not discharge wastewater and waste gas, has high economic value and meets the green and environment-friendly production requirements.

The present application relates to a ternary blended lithium manganese iron phosphate material, and a preparation method therefor and the use thereof. The ternary blended lithium manganese iron phosphate material comprises a ternary single crystal material, a ternary polycrystal material and lithium manganese iron phosphate, wherein the particle size distribution of the ternary single crystal material is between that of the ternary polycrystal material and that of lithium manganese iron phosphate. In the present application, the particle size distribution of the ternary single crystal material is between large particles of the ternary polycrystal material and small particles of lithium manganese iron phosphate; the particle size distribution of the blended material is wider; and the particles having a relatively small particle size can fill gaps among larger particles, such that the compaction density of the material is improved to a certain extent. According to the particle size distribution, the overall particle size distribution of the lithium manganese iron phosphate material blended with the ternary polycrystal and ternary single crystal material is widened, such that the stability of lithium ions during the in-out charge-discharge process of ternary material lattices is improved, and an elastic strain force is provided for the material to be impacted by an external force, thereby improving the safety and cycling performance of the material.

The invention relates to the technical field of preparation of lithium ion battery positive electrode materials, in particular to a method for regulating and controlling a high-exposure {010} crystal face of a manganese-rich phosphate-based positive electrode material, which comprises the following steps: weighing manganese salt (MnO2, MnC2O4. 2H2O, MnCO3, Mn (H2PO4) 2, MnC4H6O4. 4H2O and the like), ferric salt (FeSO4. 7H2O, Fe2O3, FePO4 and the like), lithium salt (LiOH, Li2CO3, CH3COOLi, LiH2PO4 and the like), phosphate (NH4H2PO4) and sulfate (MgSO4, NaSO4, FeSO4. 7H2O and the like) according to the molar ratio of (1-n): n: 1: 1: 0.01 (n = 0.4, 0.5, 0.6 and 0.7), adding 10-50% of organic drying at the temperature of 80-110 DEG C to obtain a precursor; putting the precursor into a tubular furnace, presintering for 2-5 hours at the temperature of 300 DEG C in an argon atmosphere, and then naturally annealing; and heating to 700 DEG C, sintering for 6-10 hours in an argon atmosphere, and naturally annealing to obtain the lithium manganese iron phosphate positive electrode material with the highly exposed {010} crystal face. After the highly-exposed {010} crystal face material LiMn0. 6Fe0. 4PO4 prepared by the method disclosed by the invention is circulated for 300 times at a high rate of 5C, the specific discharge capacity retention rate is as high as 95.7% and is far higher than 50.4% of that of an unmodified control sample.

This invention relates to the field of lithium-ion battery cathode material technology, specifically to a method for preparing and applying lithium manganese iron phosphate cathode material. The method for preparing the lithium manganese iron phosphate cathode material includes the following steps: (a) performing a first milling on a mixture containing a manganese source, a phosphorus source, a dispersant, and a ball milling aid to obtain a first slurry; performing a second milling on a mixture containing an iron source, a lithium source, and a carbon source to obtain a second slurry; (b) mixing the first slurry and the second slurry, followed by ball milling and drying to obtain a lithium manganese iron phosphate precursor; and (c) subjecting the lithium manganese iron phosphate precursor to two-stage sintering and pulverization under an inert atmosphere. The method for preparing the lithium manganese iron phosphate cathode material has advantages such as simple synthesis, low pollution, low process requirements, and good uniformity and conductivity of the prepared material.

This invention belongs to the field of iron and steel smelting technology, specifically disclosing an automatic control smelting method for high-silicon and high-manganese molten iron converters with dual slag. The method includes: S1: preparing molten iron with the following conditions: temperature 1220-1400℃, silicon content 0.70%-0.99%, manganese content ≥0.60%, and the molten iron ratio controlled below 74%; S2: using a five-hole oxygen lance for blowing, with the lance lowered in stages during the initial blowing and ignition phases and the rapid oxidation period of silicon and manganese; S3: calculating the timing for slag removal based on the silicon content of the molten iron entering the furnace, and performing slag removal when the preset oxygen consumption is reached, discharging the highly oxidizing slag generated under high-silicon and high-manganese conditions; S4: a second lance lowering, using a phased mode for subsequent smelting; S5: throughout the blowing process, slag-forming raw materials lime, magnesium balls, and sintered ore are added in batches according to set nodes. This method achieves precise control of the slag removal timing through quantitative calculation, stabilizing the residual silicon content within the target range.

The application belongs to the technical field of lithium battery cathode material preparation, and relates to a method for recycling and preparing lithium manganese iron phosphate and the lithium manganese iron phosphate. First, recycled lithium iron phosphate black powder, a manganese source and deionized water are uniformly mixed according to a proportion, a precipitant is added in the process, the mixed slurry is filtered after synthesis is completed, and the filter cake is dried to obtain a solid product; the solid product is placed in a calcining furnace for first sintering to obtain a precursor 1; then the precursor 1 is mixed with a phosphorus source, a lithium source and a carbon source according to an element proportion, sand grinding and spray granulation are performed under deionized water as a solvent to obtain a precursor 2; the precursor 2 is placed in an atmosphere furnace for second sintering, and lithium manganese iron phosphate cathode material is obtained after crushing, screening and iron removal. The raw material of the application is recycled material, which is low in price and can reduce the recycling cost; the prepared lithium manganese iron phosphate material is excellent in processing and electrical performance, and the process and operation are easy to be industrialized for large-scale production.

The positive electrode active material includes olivine lithium manganese iron phosphate. The olivine lithium manganese iron phosphate includes a dopant at a manganese-iron site. At the manganese-iron site, the dopant satisfies a relationship of “dFe-X<dMn-X”. The term “dFe-X” represents a nearest-neighbor atomic distance between the dopant and iron. The term “dMn-X” represents a nearest-neighbor atomic distance between the dopant and manganese.

This utility model relates to a magnetic separation device for recovering manganese-iron ore slag, belonging to the field of manganese-iron ore slag recovery technology. It mainly includes a conveying mechanism, a magnetic separation component, a lifting mechanism, and a weak magnetic enhancement component. The conveying mechanism is used for material transport; the magnetic separation component forms a magnetic field coverage area through a main magnet and an auxiliary magnet; the weak magnetic enhancement component is located below the conveyor belt and enhances the adsorption capacity for weakly magnetic substances through an electromagnetic coil group and a magnetic guide plate group; the lifting mechanism adjusts the height of the weak magnetic enhancement component. This application can significantly improve the capture capacity of weakly magnetic substances, reduce the loss of valuable metals, adapt to various material characteristics, and improve resource recovery efficiency, possessing high practicality and promotional value.

This invention provides a method for preparing ferrous manganese phosphate, comprising mixing an iron source, a manganese source, and phosphoric acid, adding a phosphorus source, controlling the pH value to 3.0-4.0, and preparing a mixed solution; then adding an ammonia solution A to a reaction vessel, and simultaneously adding the mixed solution A and ammonia solution B dropwise under an inert gas atmosphere, controlling the pH value throughout the reaction process to (7.5-8.0) ± 0.1, and co-precipitating to obtain ferrous manganese phosphate. The ferrous manganese phosphate prepared by this invention has uniform Mn, Fe, and P content and stable ratio.

The application provides a preparation method of a manganese iron ammonium phosphate precursor and a lithium manganese iron phosphate. The preparation method of the precursor comprises the following steps: preparing an ammonia water solution; preparing a mixed metal salt solution containing manganese and iron; preparing a phosphorus source solution; adding a small amount of the ammonia water solution as a reaction bottom solution, adding the remaining ammonia water solution, the mixed metal salt solution and the phosphorus source solution into a reaction kettle in parallel flow to perform a reaction, maintaining the pH at 5-5.5, then increasing the reaction temperature to 90 DEG C, aging, and obtaining a manganese iron ammonium phosphate monohydrate precipitate; and then performing solid-liquid separation, washing and drying to obtain a manganese iron ammonium phosphate precursor powder. The ammonia water solution is used as the bottom solution, the yield of the manganese iron ammonium phosphate precursor is improved, a secondary phosphorus source is added in an acidic environment, the proportion of P elements in the precursor is increased, the iron-phosphorus ratio is closer to the theoretical value, and the yield is higher. The process is simple, the yield is high, the method is more suitable for large-scale production, and has great market prospects.

The application discloses a carbon-coated manganese iron lithium phosphate composite material and a preparation method and application thereof, and relates to the technical field of battery materials. x Fe y M z PO4; wherein M comprises Re, Ti, Mo and Zr elements; 0.55<=x<=0.65, 0.35<=y=1-x-z<=0.45, 0.025<=z<=0.035. The application can improve ion conductivity, stability of crystal structure, interface dynamics and stability under high temperature and high pressure of the manganese iron lithium phosphate by doping the manganese iron lithium phosphate with Re, Ti, Mo and Zr elements.

This invention discloses a method for reducing the refining cost of low-carbon cold heading steel, belonging to the field of iron and steel metallurgical technology. The method includes: recovering molten slag before tapping from the converter; reducing carbon content to below 0.06% in the later stages of smelting; bottom blowing argon after oxygen blowing and measuring oxygen content, dynamically calculating the addition amounts of ferroaluminum and lime; adding ferroaluminum and lime during tapping; adjusting aluminum to 0.050%-0.055% after tapping by feeding aluminum wire; slag breaking and power supply after the molten steel reaches the LF furnace, adding lime at 1.3 times the amount of aluminum added after tapping; raising the temperature to 1600-1605℃ after a second sampling, adding ferromanganese, calculating aluminum loss based on power supply time, and controlling aluminum at 0.035%-0.040%; finally, calcium treatment and soft blowing are performed. This invention achieves low-cost and high-efficiency refining of low-carbon cold heading steel through optimizations such as recovering molten slag, dynamically calculating material addition amounts, moving deoxidation and slag formation forward, reducing material consumption, and replacing large-scale argon agitation for impurity removal.

The invention provides a preparation method of a manganese iron oxide-based lithium manganese iron phosphate positive electrode material, which comprises the following steps: (1) mixing manganese iron oxide, a phosphorus source, a lithium source, an additive and a reducing agent in proportion to obtain a premix; (2) sintering the premix obtained in the step (1) in an inert atmosphere to prepare a lithium iron manganese phosphate precursor; (3) mixing the precursor with a carbon source, an LATP solid electrolyte and water to prepare slurry, and grinding the slurry by a horizontal sand mill until the particle size D50 is 100-200 nm; and (4) carrying out spray drying and secondary sintering on the ground material to obtain the lithium iron manganese phosphate positive electrode material. By adopting the process, the lithium manganese iron phosphate positive electrode material can be finely ground within a short time, and the problem that the manganese iron oxide is difficult to grind is solved.

The application discloses a manganese iron hydrogen phosphate material and a preparation method and application thereof, relates to the technical field of battery materials. The chemical formula of the manganese iron hydrogen phosphate material is as follows: Fe x Mn (1‑x) HPO4, wherein x is 0.1-0.7.The manganese iron hydrogen phosphate material is used in a lithium battery, and the platform voltage of the manganese iron hydrogen phosphate material reaches 4.1v, the cycle life is greatly improved in comparison with a lithium iron phosphate battery, in addition, the manganese material is rich in domestic reserves, is easy to obtain, is low in price, and is small in environmental hazards, and the manganese iron hydrogen phosphate material can make up for the shortcomings of ternary and lithium iron phosphate.

The invention belongs to the technical field of high-titanium welding wire steel, and relates to a method for controlling the titanium element of the high-titanium welding wire steel, which comprises the following steps of: according to the target component of the high-titanium welding wire steel, sequentially carrying out converter or electric furnace smelting, LF (ladle furnace) refining and continuous casting production, when tapping in the smelting process, adding ferrosilicon alloy with the same silicon mass according to the target silicon component mass of 90% of the high-titanium welding wire steel, medium-carbon ferromanganese with the mass equal to that of manganese is added according to the total amount of 90% of the target manganese component of the high-titanium welding wire steel; in the refining process, after deoxidation is completed, the content of (FeO + MnO) in refining slag is controlled to be 1.0% or below, then a low-aluminum low-nitrogen ferrotitanium wire is fed through a wire feeder for fine adjustment of the titanium element, the titanium content in molten steel is controlled within a target range, and meanwhile the content of aluminum and nitrogen in the molten steel is controlled within a steel grade required range; a whole-course protection pouring process is adopted in the continuous casting process, so that titanium content loss caused by secondary oxidation of molten steel is prevented.

The application discloses a kind of corrosion-resistant reducing flange and preparation method thereof, belong to reducing flange preparation technical field, manganese iron, silicon iron, iron ingot, copper ingot and graphite quality carbon additive are added into smelting furnace, smelt under argon protection, then add slag remover and stir evenly, after deslagging, rare earth alloy with silica coated magnesium oxide nano powder smelted is added, continue smelting, alloy liquid is cast into mould, and is cast into shape, it is immersed in electrolyte and is treated by anodic oxidation, surface is coated with polyamide imide primer, after solidification, polytetrafluoroethylene powder finish is sprayed using electrostatic spraying equipment, after electrostatic spraying, reducing flange semi-finished product is transferred to curing oven, and is cooled and taken out, to obtain a kind of corrosion-resistant reducing flange;The corrosion-resistant reducing flange has good high adhesion, high temperature resistance, long-acting anticorrosion performance.

The invention discloses a composite lithium manganese iron phosphate positive electrode material and a preparation method thereof, the chemical formula of the composite lithium manganese iron phosphate positive electrode material is LiMnx-aMgaFe1-xPO4, a is equal to 0.01-0.03, x is equal to 0.5-0.8, and the surface of lithium manganese iron phosphate is sequentially coated with a carbon layer and a sulfonated manganese phthalocyanine layer from inside to outside; the preparation method comprises the following steps: mixing a lithium source, a manganese source, an iron source, a phosphorus source, a magnesium source, a carbon source and water to prepare slurry, and granulating and calcining to obtain carbon-coated lithium manganese iron phosphate particles; and mixing, grinding and spray-drying the carbon-coated lithium manganese iron phosphate particles, sulfonated manganese phthalocyanine and a dispersing agent to obtain the composite lithium manganese iron phosphate positive electrode material. According to the positive electrode material, manganese dissolution can be effectively inhibited, and the manganese dissolution rate is lower than 30.9 ppm; and meanwhile, the composite material also has remarkable advantages in the aspects of compaction density, ion / electron conductivity, cycle life and the like.

The invention relates to a lithium manganese iron phosphate positive electrode material with consistent morphology, a preparation method and a positive electrode, and the preparation method comprises the following steps: mixing a manganese salt solution, a ferrite solution and an antioxidant in a protective atmosphere to obtain a transition metal mixed solution; mixing phosphoric acid, a lithium source and a transition metal mixed solution, and adjusting the pH value to 5-7 to obtain a first solution; performing a first hydrothermal reaction on the first solution, then mixing the first solution with the MOF mixture, and performing a second hydrothermal reaction to obtain a lithium manganese iron phosphate precursor; and mixing a carbon source and the lithium manganese iron phosphate precursor, and sintering under a protective atmosphere condition to obtain the lithium manganese iron phosphate positive electrode material with consistent morphology. According to the lithium manganese iron phosphate positive electrode material with the consistent morphology, provided by the invention, the preparation controllability of the lithium manganese iron phosphate can be remarkably improved, the positive electrode material with uniform elements, consistent morphology and stable performance is obtained, and the application requirements of power batteries and energy storage batteries are met.