364 results about "Lithium sulphate" patented technology

The invention provides a method for preparing high-purity and fine-particle-size lithium sulfide based on carbon thermal reduction. The method comprises the following steps: weighing lithium sulfate monohydrate, an insoluble inorganic carbon source and cysteine in a set proportion to form a raw material mixture; mixing the raw material mixture with water according to a set solid-to-liquid ratio, performing ultrasonic dispersion to obtain homogeneous dispersion liquid, and enabling the dispersion liquid to pass through a nitrogen circulating spray dryer to obtain uniform and dry precursor powder; in a vacuum environment, carrying out segmented calcination to obtain a crude product lithium sulfide; and in a dry and anhydrous environment, washing the crude product lithium sulfide for multiple times by using absolute ethyl alcohol according to a set liquid-solid ratio to obtain an alcoholic solution containing lithium sulfide, and then obtaining lithium sulfide fine powder through a nitrogen circulating spray dryer. The invention solves the problems of side reaction, low purity, large product particles, uncontrollable particle size and the like of lithium sulfide prepared by a carbon thermal reduction method in the prior art.

The invention discloses high-purity lithium sulfide as well as a preparation method and application thereof. The preparation method comprises the step that lithium hydride, lithium hydroxide and a sulfur source are subjected to a heating reaction in a dry inert atmosphere, and the high-purity lithium sulfide is obtained. The molar ratio of lithium hydride to lithium hydroxide is X: (10-X), and X is 1-6. The invention also discloses the prepared high-purity lithium sulfide and application of the high-purity lithium sulfide in preparation of sulfide solid electrolyte. Lithium hydroxide and lithium hydride are mixed to serve as a lithium source in lithium sulfide preparation, the lithium hydroxide quickly and uniformly reaches the reaction temperature by means of the characteristic that the lithium hydride reacts with a sulfur source to release heat and produce gas, the lithium hydride reacts to produce gas, meanwhile, discharging of product water vapor is facilitated, and oxygen in the environment is isolated; and hardening and generation of a side reaction product lithium sulfate are prevented, the conversion rate of lithium hydroxide to lithium sulfide is improved, and the raw material and process cost for preparing lithium sulfide is remarkably reduced.

The invention discloses a method for preparing battery-grade iron phosphate and lithium carbonate from a waste lithium iron phosphate battery, and belongs to the technical field of lithium batteries, the method comprises the following steps: slurrying a waste lithium iron phosphate positive electrode material, adding concentrated sulfuric acid for leaching, adding sodium sulfite, controlling reaction potential, and carrying out filter pressing after reaction to obtain a leachate; iron is added into the leachate to remove copper, and copper-removed liquid and copper slag are obtained after filter pressing; adding sodium dihydrogen phosphate into the copper-removed liquid to remove aluminum, and carrying out filter pressing to obtain aluminum slag and impurity-removed liquid; adjusting the pH value of the impurity-removed solution, adding hydrogen peroxide, reacting to obtain an iron phosphate dehydrate precipitate and an iron phosphate mother solution, and treating the iron phosphate dehydrate to obtain battery-grade anhydrous iron phosphate; adjusting the pH value of the iron phosphate mother liquor, carrying out filter pressing to obtain impurity-removed slag and a lithium sulfate solution, adding sodium carbonate into the lithium sulfate solution, carrying out heating reaction, filtering slurry to obtain a lithium carbonate wet material, and treating to obtain battery-grade lithium carbonate. According to the method, the problem of recycling the waste lithium iron phosphate battery material iron phosphate is solved, and comprehensive recycling of the iron phosphate and the lithium material is realized.

The invention discloses a large-scale preparation method of lithium sulfide, and belongs to the technical field of preparation of battery materials. Lithium sulfate monohydrate is adopted as a reaction raw material and is subjected to dehydration and purification treatment to obtain anhydrous lithium sulfate, and the anhydrous lithium sulfate is calcined in hydrogen and carbon dioxide mixed gas without introducing other impurities; the method has the advantages that safety under high-temperature calcination reaction can be guaranteed, the produced lithium sulfide crude product is dissolved by the methanol / isopropanol mixed solution to directly generate lithium sulfide crystals, redundant impurities can be removed by calcining the generated lithium sulfide crystals, no other by-products are generated in the reaction process, and the purity of lithium sulfide is guaranteed. According to the Li2S preparation method developed by increasing the purification step and exploring the reaction conditions and the impurity removal mode, low-cost, high-purity and large-scale preparation of Li2S can be realized.

The invention relates to the technical field of preparation of lithium battery materials, and discloses a synthesis method of a low-cost battery-grade lithium dihydrogen phosphate raw material lithium phosphate. The synthesis method comprises the following steps: dissolving crude lithium sulfate in alkaline lithium phosphate lithium precipitation mother liquor; carrying out chemical precipitation on the filtered lithium sulfate solution to preliminarily remove calcium, and subsequently, deeply removing calcium and COD (Chemical Oxygen Demand) by sequentially using activated carbon and calcium removal resin to obtain a lithium sulfate finished solution; mixing the lithium sulfate completion liquid and the alkali liquid, freezing to-10 DEG C to-3 DEG C, and performing centrifugal separation to obtain a lithium sulfate freezing liquid; and reacting the refrigerating fluid with a dilute phosphoric acid solution to precipitate lithium phosphate, stirring, washing and centrifuging the filtered crude product lithium phosphate, and drying to obtain the battery-grade lithium dihydrogen phosphate raw material lithium phosphate. The lithium phosphate prepared at low cost is used for replacing battery-grade lithium carbonate, lithium hydroxide and the like as a lithium source for producing the lithium dihydrogen phosphate, so that the production cost of the battery-grade lithium dihydrogen phosphate can be effectively reduced, the lithium phosphate mother liquor is recycled, and the problem of treating a large amount of wastewater caused by other methods is solved.

The invention discloses an early-strength high-fluidity cement-based grouting material and a preparation method thereof, and belongs to the technical field of grouting materials. The grouting material is prepared from the following raw materials in percentage by mass: 40-50% of cement, 3-5% of an early strength agent, 0.5-1.5% of a water reducing agent, 3-20% of a mineral admixture, 0.2-1% of a defoaming agent and 35-50% of aggregate, the early strength agent is a composition of a ground nano seed crystal early strength agent based on hydrated calcium silicate and lithium sulfate, and the water reducing agent is an asparaginic acid ester modified polycarboxylic acid water reducing agent. According to the invention, high fluidity and high stability of the cement-based grouting material are realized, the problem of insufficient early strength of the traditional grouting material is solved, and sufficient grouting in a complex and narrow construction environment can be met.

The invention relates to the technical field of preparation of lithium sulfide, in particular to a method for preparing lithium sulfide through hydrogen reduction of lithium sulfate. According to the specific technical scheme, the method for preparing the lithium sulfide by reducing the lithium sulfate through the hydrogen comprises the steps that the lithium sulfate is smashed to be micron-sized and then fed into a fluidized bed reactor, then high-purity hydrogen preheated to 850 DEG C is introduced into the fluidized bed reactor from the bottom of the fluidized bed reactor, the reaction temperature is controlled to be 850 + / -20 DEG C, and the reaction time is controlled to be 5-10 min. The hydrogen reduction method is relatively low in reaction temperature (700-900 DEG C), hydrogen is used as a clean reducing agent, a reaction byproduct is only water, and the problems of insufficient purity, high energy consumption, serious environmental pollution and the like in a traditional lithium sulfide preparation method can be avoided. The introduction of the fluidized bed technology can greatly enhance the gas-solid phase heat and mass transfer efficiency, realizes the continuity and automation of the process, and is an important path for realizing the industrialization of the reaction.

The invention provides a method for cyclically regenerating a positive electrode active material by using magnesium sulfate, which comprises the following steps: 1) burdening and mixing waste lithium battery black powder, magnesium sulfate and a carbon source, and roasting the mixture in a vacuum or inert atmosphere to obtain a roasted product; (2) adding the roasted product into water to carry out water leaching treatment, and carrying out suction filtration to obtain a lithium sulfate solution and water leaching residues; 3) adding the lithium sulfate solution into the saturated sodium carbonate solution for lithium precipitation to obtain a lithium carbonate precipitate; (4) drying the water leaching residues, adding dilute sulphuric acid to carry out acid leaching treatment, filtering to obtain acid leaching residues and a magnesium sulfate solution, and then carrying out evaporative crystallization treatment on the magnesium sulfate solution to obtain a magnesium sulfate precipitate; 5) mixing the acid leaching residues with lithium carbonate, and sintering to obtain the regenerated ternary positive electrode active material.According to the method, the recovery rate of obtained lithium reaches 99% or above, loss of important elements in the regeneration process can be avoided, cyclic utilization of magnesium sulfate is achieved, and consumption of chemical reagents and secondary pollution are reduced.

The invention relates to the technical field of battery raw materials, in particular to a preparation method of lithium sulfide powder, the lithium sulfide powder and application, and the preparation method comprises the following steps: uniformly mixing lithium sulfate and a carbon source according to a preset proportion to obtain a first mixture; performing first heat treatment on the first mixture in inert gas to obtain a second mixture; and performing second heat treatment on the second mixture in reducing gas to obtain the lithium sulfide powder. The product obtained by the preparation method disclosed by the invention is the lithium sulfide powder, and the obtained lithium sulfide powder has the advantages of less oxygen and carbon impurities, higher purity and high reaction activity, and meets the synthesis requirements of the electrolyte; according to the preparation method, in the process of preparing lithium sulfide, toxic gas and organic solvent are not used, the reaction temperature is low, the energy consumption is low, the requirement on production equipment is low, the process is simple, the cost is low, harmful gas emission is avoided, safety and environment friendliness are achieved, and industrialization is easy to achieve.

The invention relates to the technical field of lithium sulfide preparation, and particularly discloses a preparation method of lithium sulfide. The preparation method of the lithium sulfide comprises the following steps: grinding and mixing lithium sulfate, chitin and derivatives thereof, then putting the mixed material into a corundum crucible, putting the corundum crucible into a tubular furnace, heating to 250 DEG C at a heating rate of 7 DEG C / min in a nitrogen atmosphere, keeping the temperature for 1 hour, and cooling to room temperature to obtain the lithium sulfide. Then heating to 300 DEG C at a heating rate of 1 DEG C / min in a nitrogen atmosphere, keeping the temperature for 5 hours, carrying out a carbonization coating reaction, then heating to 700 DEG C at a heating rate of 5 DEG C / min in a nitrogen atmosphere, keeping the temperature for 10 hours, carrying out an oxidation-reduction reaction, and finally grinding to obtain lithium sulfide. The preparation method of the lithium sulfide powder provided by the invention is simple in process flow, the requirement on environment control is reduced, and the preparation method is low in raw material price, relatively few in working procedures, low in preparation cost and suitable for large-scale industrial production.

A method of extracting purified lithium sulfate brine from sedimentary rock is disclosed. The method includes the steps of sizing sedimentary rock ore, suspending the sized ore in an aqueous solution, and separating the aqueous solution into lithium bearing slurry and low lithium gangue. The lithium bearing slurry is then treated with an acid, dissolving lithium from the sedimentary rock and forming precipitates which are subsequently removed the slurry, forming an acidic lithium sulfate filtrate solution. The pH of the acidic lithium sulfate filtrate solution is then modified to form further precipitates which are then separated. The neutralized lithium sulfate solution is then crystallized to remove magnesium and potassium, and treated with quicklime, soda ash solution, and / or oxalic acid to form additional precipitates. Finally the additional precipitates are separated from the solution, and the solution is passed through an ion exchange apparatus, forming a purified lithium sulfate brine.

The application discloses a method for preparing high-purity battery-grade lithium sulfide by reducing lithium sulfate with a reducing gas. The specific steps are as follows: raw material lithium sulfate and inert wave-absorbing substances are mixed, uniformly mechanically ball-milled, tablet-pressed, sieved, put into a microwave reactor, and then a reducing gas is introduced for microwave heating reaction; after cooling to room temperature, the mixture is discharged into another reactor, ethanol is added for dissolution, mechanical stirring is carried out, and then standing and filtration are performed; the inert wave-absorbing substances are recycled and reused; an ethanol solution of dissolved lithium sulfide is obtained; crude lithium sulfide is obtained by heating and distillation; after freeze-drying, the crude lithium sulfide is heated and secondarily calcined in a rotary furnace under the protection of inert gas, and finally battery-grade high-purity lithium sulfide is obtained. By mixing the inert wave-absorbing substances with the lithium sulfate and heating by the microwave method, the contact surface of the lithium sulfate and the gas can be improved, and in addition, the internal heating method can be used to avoid the lithium sulfide formed on the outer surface from wrapping the raw material lithium sulfate, so as to affect the hydrogen reduction efficiency.

The invention discloses a preparation method of lithium trifluoromethanesulfinate, and belongs to the field of lithium ion battery materials. The preparation method of the lithium trifluoromethanesulfinate comprises the following steps: 1, mixing trifluoromethanesulfonyl chloride, lithium sulfite, lithium bicarbonate and a first solvent, and heating to react; 2, dissolving the concentrated crude product in a second solvent, and filtering and separating a lithium sulfate solid; and 3, concentrating the filtrate, adding a third solvent, uniformly stirring, filtering and separating the lithium chloride solid, and concentrating to obtain the lithium trifluoromethanesulfinate. According to the method for preparing the lithium trifluoromethanesulfinate, the yield can reach 94%, the operation is simple, byproducts are easy to separate, and the method is suitable for industrial production. In addition, the obtained by-product lithium sulfate can be used for preparing lithium sulfide, the by-product lithium chloride can be used for preparing solid electrolyte, and resource utilization is achieved.

The invention discloses electronic-grade lithium sulfide as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing lithium sulfate with hydrogen under a vacuum condition, and carrying out a reduction reaction to prepare the electronic-grade lithium sulfide. According to the preparation method of the electronic-grade lithium sulfide, lithium sulfate is reduced through hydrogen, no waste gas or waste water is generated in the process, environment friendliness is achieved, unreacted hydrogen and water vapor return to the hydrogen storage tank, hydrogen can be reused, the water vapor settles to the bottom of the tank to be recycled after being condensed, the technological process is short, and the product purity is high; the method is suitable for large-scale popularization and application.

The invention discloses a process for extracting lithium from lepidolite through low-temperature roasting, which comprises the following steps: uniformly mixing lepidolite mineral powder with ferrous sulfate, sodium sulfate and calcium oxide, roasting at 800-900 DEG C for 1-2 hours, and cooling to room temperature to obtain a roasted material; adding water into the roasted material to prepare slurry, performing wet grinding to obtain ball-milled slurry, performing water leaching on the slurry, and performing suction filtration to obtain lithium sulfate leaching liquid and leaching residues; treating the leaching solution to obtain a lithium precipitation pre-solution, and further carrying out lithium precipitation reaction to obtain a lithium carbonate crude product; and finally, mixing the crude lithium carbonate product with deionized water, heating, stirring, washing and carrying out solid-liquid separation to obtain a battery-grade lithium carbonate product. The lithium extraction process of the lepidolite can be realized under the roasting condition of 800-900 DEG C, and the roasting temperature is effectively reduced; meanwhile, on the basis of the low-temperature roasting condition, Li2SO4 and LiKSO4 can still be extracted to the maximum extent, and release of SO2, SO3 and HF is avoided.

The invention discloses a preparation method of battery-grade lithium hydroxide monohydrate, which comprises the following steps: causticizing a lithium sulfate concentrated solution, freezing and crystallizing to obtain a frozen solution, precisely filtering the frozen solution, filtering by adopting an alkali-resistant nanofiltration membrane, collecting a penetrating fluid, and when the permeability of the alkali-resistant nanofiltration membrane is reduced, filtering by adopting an alkali-resistant nanofiltration membrane to obtain the battery-grade lithium hydroxide monohydrate. The alkali-resistant nanofiltration membrane is cleaned by lithium bicarbonate thermal decomposition mother liquor of a lithium carbonate production line, and all collected penetrating fluid is subjected to evaporative crystallization and centrifugal drying to obtain the battery-grade lithium hydroxide monohydrate. By adopting a method of nanofiltration membrane impurity removal and primary evaporative crystallization, the nanofiltration membrane impurity removal is used for replacing the primary evaporative crystallization in the prior art, so that the energy consumption can be effectively reduced, the production cost is saved, the Si content of the nanofiltration solution is lower than 3ppm and lower than that of the primary evaporative crystallization heavy solution, and the method can be used for preparing high-quality battery-grade lithium carbonate. The Si content of the prepared lithium carbonate is lower than 20 ppm.

The invention discloses a method for determining the content of lithium sulfide based on a gravimetric method, and belongs to the field of battery material detection. The invention discloses a method for determining the content of lithium sulfide based on a gravimetric method. The method comprises the following steps: A, oxidizing lithium sulfide into lithium sulfate at high temperature; b, converting lithium sulfate into barium sulfate precipitate; c, burning the precipitate at high temperature and keeping the weight constant; and D, calculating the content of lithium sulfide according to barium sulfate. According to the method, the content of lithium sulfide is measured through a gravimetric method, the problem that the content of lithium sulfide cannot be accurately measured in the industry is solved, and the method is easy to operate, high in accuracy, good in precision and safer.

The invention discloses a method for separating and recycling phosphorus, iron and lithium in battery black powder, and relates to the technical field of battery recycling. The method comprises the following steps: carrying out acid leaching on battery black powder to obtain a battery black powder leaching solution and filter residues; an oxidizing agent is added into the battery black powder leaching solution, the pH of the solution is adjusted to 1.8-2.5, solid-liquid separation is conducted after the reaction is completed, and iron phosphate sediment and a lithium-containing solution are obtained; adjusting the pH value of the lithium-containing solution to 10-12, and carrying out solid-liquid separation after the reaction is completed to obtain a metal precipitate and a lithium sulfate solution; dissolving the iron phosphate precipitate in a sulfuric acid solution, adding a reducing agent to reduce ferric iron into ferrous iron, separating out ferrous sulfate by adopting an alcohol precipitation method or an ammonium sulfate crystallization method, and performing solid-liquid separation after the reaction is completed to obtain ferrous sulfate precipitate or ammonium ferrous sulfate crystals and mother liquor; and evaporating and concentrating the mother liquor, and extracting to obtain a phosphoric acid solution. According to the method, the three elements of phosphorus, iron and lithium in the battery black powder can be recycled, and the environmental problem caused by stacking of the lithium extraction slag can be avoided.

The utility model discloses a liquid-phase synthesis system of lithium sulfide. Comprising a first lithium sulfate dissolving device, a first barium sulfide dissolving device, a chemical combination reaction device, a first separation device and a second separation device, the liquid phase after-treatment unit is used for concentrating, purifying and drying the liquid phase to obtain lithium sulfide, and the solid phase after-treatment unit is used for washing and drying the solid phase to obtain barium sulfate; the first lithium sulfate dissolving device and the first barium sulfide dissolving device are both connected with a raw material inlet of the combination reaction device; and a reaction product outlet of the combination reaction device is connected with the first separation device. The liquid-phase synthesis system of the lithium sulfide has the advantages that products are easy to separate, the purity of the lithium sulfide products is high, the liquid-phase synthesis system of the lithium sulfide is very suitable for industrial-scale production, and the produced high-purity anhydrous lithium sulfide is very suitable for solid-state battery anode materials and has huge potential economic benefits.

The invention discloses a method for preparing high-purity lithium sulfide from a lithium sulfate mother liquor, which comprises the following steps: preparing a lithium sulfate concentrated liquor: adding 98% concentrated sulfuric acid into the lithium sulfate mother liquor to adjust the pH value, adjusting the pH value to 6-7, carrying out precise filtration to filter out possible impurities to obtain a filtrate, introducing the filtrate into an MVR evaporation system, and concentrating the mother liquor to obtain a concentrated liquor, performing freezing crystallization on the concentrated solution by using a cooling crystallizer, and then performing centrifugal separation under the action of a centrifugal machine to obtain solid slag which is mirabilite and a solution which is lithium sulfate concentrated solution; and preparing crude lithium sulfide: performing evaporative crystallization on the obtained lithium sulfate concentrated solution, adding pure water for slurrying, and performing centrifugal filtration and cleaning for 2-3 times. The impurity content is effectively controlled through a multi-stage purification process, the Li2S product with the purity larger than or equal to 99.95% is finally obtained, the key technical problem of direct conversion from a liquid battery recycling material to a solid battery positive electrode raw material is solved, and core material support is provided for lithium battery industry closed loop and industrial product iteration.

The invention discloses a lithium dihydrogen phosphate preparation method, which comprises: S1, mixing a refined lithium sulfate solution with an extraction agent solution, and carrying out standing layering to obtain an upper layer solution; s2, mixing the upper-layer solution with a detergent, washing, and separating to obtain a washing solution; s3, mixing the washing liquid with a phosphoric acid solution, and standing for layering to obtain a lower-layer solution; s4, mixing the lower-layer solution with a component regulator; and carrying out solid-liquid separation. An extracting agent in the extracting agent solution comprises at least one of benzoyl trifluoroacetone, trialkyl phosphine oxide and sulfonated calixarene. The specific extraction agent efficiently selects lithium ions to separate impurities, lithium dihydrogen phosphate is obtained through direct reverse extraction after washing, lithium dihydrogen phosphate does not need to be converted into other lithium products to prepare lithium dihydrogen phosphate, and the process production period is shortened. In addition, lithium dihydrogen phosphate is prepared through washing and reverse extraction after impurities are efficiently selected and separated through an extraction agent; the purity is high; the battery grade lithium dihydrogen phosphate can be obtained.

The invention discloses a quick-hardening early-strength concrete mineral additive and a preparation method thereof, and belongs to the technical field of building materials. The additive comprises the following components in parts by weight: 50-75 parts of a mineral active material (compounded by silica fume, slag powder and metakaolin), 15-30 parts of a composite activator (sodium silicate, lithium sulfate and triethanolamine synergistically), 5-10 parts of a sustained-release microcapsule (calcium sulphoaluminate coated with nano-silica) and 2-5 parts of an auxiliary thickening agent (compounded by HPMC and a water reducing agent). The preparation method comprises the steps of mineral activation, excitant reaction and mixing of the microcapsule and the thickening agent. After the additive is doped into concrete, the 3h compressive strength is greater than or equal to 15MPa, the initial setting time is less than or equal to 5min, and the additive has low resilience (less than or equal to 13%), high durability (impermeability is greater than or equal to P11) and environmental adaptability (-5 DEG C strength fluctuation ratio is less than or equal to 9%). And compared with the prior art, the cost is reduced by 40%, and the method has remarkable economic and social benefits.

The invention discloses lithium sulfide and a preparation method thereof. The preparation method comprises the following steps: (1) carrying out ball-milling mixing on iron powder, sodium sulfide and lithium sulfate in a first inert atmosphere to obtain a mixture; (2) calcining the mixture in a second inert atmosphere for the first time to obtain a reaction material; (3) stirring and washing the reaction material with an alcohol solvent in a third inert atmosphere, filtering to obtain filtrate and a filter cake, performing reduced pressure distillation on the filtrate to obtain a lithium sulfide crude product, washing the filter cake with deionized water, and filtering to obtain a solid by-product; and (4) carrying out secondary calcination on the lithium sulfide crude product in a fourth inert atmosphere to obtain lithium sulfide. The preparation method provided by the invention has the advantages of few synthesis steps, simple product purification and environmental protection.

The invention provides an MVR (Mechanical Vapor Recompression) evaporative crystallization system and an evaporative crystallization method for coarsely preparing lithium sulfate monohydrate. The lithium sulfate MVR evaporative crystallization system is composed of a feeding pump, a first condensate water preheater, a non-condensable gas preheater, a lithium sulfate crystallizer, a vacuum pump, a first gas-liquid separator, a steam washing tower gas-liquid separator, a condensate water pump, a condensate water tank, a mother liquor discharge pump, a discharging pump, a mother liquor pump, a mother liquor tank, a thickener, a lithium sulfate centrifugal machine, a drying machine, a packaging machine, a steam compressor and a gas washing tower. And a scrubber tower circulating pump. According to the lithium sulfate MVR evaporative crystallization system and the lithium sulfate MVR evaporative crystallization method provided by the invention, the problems of system equipment scaling and evaporation gas-liquid entrainment can be reduced, and meanwhile, the crystal granularity is large and uniform.

The invention belongs to the technical field of medical treatment, and relates to a nucleic acid releasing agent which comprises the following components: acetonitrile, strong base, lithium dodecyl sulfate, potassium trifluoromethanesulfonate, ammonium sulfate, dimethyl sulfoxide and thiourea. The invention also relates to a microfluidic device and a detection method thereof. According to the technical scheme provided by the invention, the inhibition effect of protein on nucleic acid can be destroyed, and the inhibitor is effectively removed and amplified.

The present invention provides a preparation method and application of a carbon-coated lithium sulfide hollow sphere positive electrode material, which belongs to the field of new energy technology. The lithium sulfide / carbon composite positive electrode material is composed of a carbon layer coating a lithium sulfide hollow sphere to form a three-dimensional network structure. Preparation method: lithium sulfate spheres are prepared by spray drying, and then fully mixed with a carbon source precursor and subjected to in-situ oxidation and reduction. The composite positive electrode material prepared by the present invention can effectively reduce the cost of lithium sulfide and shorten the material preparation cycle, wherein the carbon layer has a large contact area with the hollow lithium sulfide sphere, which can significantly enhance the conductivity and electrochemical activity of the material.

The invention discloses a method for preparing battery-grade lithium phosphate based on fractional precipitation and double washing and application, according to the method, crude lithium sulfate is used as a raw material, and through an integrated process of fractional precipitation and double washing, the production cost of the lithium phosphate is reduced, and meanwhile, the yield of the battery-grade lithium phosphate is increased. The method mainly solves the problem of wrapping sodium ions and sulfate radicals as impurities in the process of precipitating crude lithium sulfate, and is suitable for industrial production of the precursor of the positive electrode material of the lithium ion battery. According to the method, the impurity content is mainly controlled from two aspects, wrapping of impurities in product grains can be reduced through fractional precipitation and crystal form induction generation, and residual impurities in grain gaps can be removed through a dual washing scheme. The purpose of crystal form induction generation is mainly to guide generation of large crystals and reduce the specific surface area of the large crystals so as to reduce the Na adsorption amount.

The invention is suitable for the technical field of grouting materials, and provides a grouting material with high durability and good bonding performance and a preparation method. Comprising the following components: 20 to 30 parts of Portland cement, 30 to 45 parts of sulphoaluminate cement, 0.5 to 2 parts of an early strength agent, 15 to 25 parts of fly ash, 5 to 10 parts of silicon dioxide, 0.5 to 1 part of soybean oil, 0.5 to 1 part of vegetable tannin, 1 to 2 parts of a water reducing agent, 0.2 to 0.5 part of fish gelatin, 0.05 to 0.15 part of a retarder and 0.05 to 0.1 part of an air entraining agent. Preferably, the grouting material further comprises blast furnace slag and wood pulp fibers, the mass fraction of the blast furnace slag is 10 to 20 parts, and the mass fraction of the wood pulp fibers is 0.1 to 0.5 part; the mass ratio of the Portland cement to the sulphoaluminate cement is 2: 3, and the early strength agent is one or more of lithium sulfate and lithium carbonate. The durability and binding property of the grouting material are remarkably improved, and the crack resistance, flexibility and constructability of the grouting material are enhanced, so that the grouting material can better adapt to complex and changeable construction environments and long-term load effects and has wide application prospects.

The invention discloses a method for directly preparing high-purity Li2S by utilizing carbothermal reduction, which comprises the following steps: ball-milling and mixing Li2SO4.H2O and a carbon source, and carrying out first-step calcination in an air atmosphere at the calcination temperature of 450-550 DEG C to obtain a first-step calcination product; carrying out ball-milling mixing on the first-step calcined product and sublimed sulfur powder, tabletting, and carrying out second-step calcination at the calcination temperature of 700-800 DEG C under the protection of inert gas to obtain a second-step calcined product; and continuously performing third-step calcination on the second-step calcination product under the protection of inert gas at the calcination temperature of 850-950 DEG C to obtain the product Li2S. Lithium sulfate and a high-purity carbon source are adopted as main raw materials, sublimed sulfur powder is introduced in the second-step calcination process to inhibit generation of Li2O, after the carbon source is consumed in the second-step calcination process, a mixture of lithium sulfide and residual lithium sulfate is obtained, the temperature continues to rise, third-step calcination is conducted, the residual lithium sulfate is molten, volatilized and removed, and the lithium sulfide is obtained. And discharging the mixture out of the tubular furnace along with the gas flow of the inert gas to obtain high-purity lithium sulfide.

The invention discloses a preparation method of high-purity lithium sulfide based on a carbon reduction method, and belongs to the technical field of material preparation. Comprising the following steps: S1, mixing anhydrous lithium sulfate with a reducing agent, and adding absolute ethyl alcohol as a solvent, S2, drying a material subjected to wet grinding, removing the absolute ethyl alcohol solvent and water, and transferring the material into a tubular furnace or an atmosphere sintering furnace to obtain a dried material; s3, the environment temperature in the furnace is increased to 600-800 DEG C at the heating rate of 5-12 DEG C / min, heat preservation is conducted for 30-60 min, and a reduction reaction is conducted; s4, after a reduction reaction product is cooled to the room temperature, adding absolute ethyl alcohol, stirring until the absolute ethyl alcohol is fully dissolved, completing solid-liquid separation through a suction filtration device, collecting filtrate and distilling; and S5, drying the distilled product to obtain the high-purity lithium sulfide. By accurately controlling the raw material purity, the reaction parameters and the purification process, the product purity is greater than or equal to 99.5%, the yield is greater than or equal to 89%, and the high-performance application requirements of solid-state batteries and the like are completely met; the method is simple in process steps, moderate in equipment requirements and suitable for large-scale industrial production.