1144 results about "LITHIUM PHOSPHATE" patented technology

The invention relates to a method for preparing a lithium iron phosphate / carbon composite material of a lithium ion battery, which belongs to the technical field of lithium ion batteries. The method for preparing the lithium iron phosphate / carbon composite material of the lithium ion battery comprises the following steps of: 1) preparing a suspending graphene-dispersed aqueous solution system, namely, crushing graphite to 1 to 5 microns, adding the crushed graphite into distilled water or purified water, adding 0.1 to 5 percent of surfactant, heating with stirring the mixed solution to 180 to 250 DEG C in a sealing way, performing stirring for 2 to 6 hours and reducing the temperature; 2) crushing lithium iron phosphate to the particle size of 1 to 5 microns, adding the crushed lithium iron phosphate into the distilled water or the purified water, adding with stirring 0.01 to 1 percent of coupling agent, performing uniform stirring, adding the graphene-dispersed aqueous solution, and performing stirring and filtration; and 3) vacuum-drying solid powder obtained by the filtration, and calcinating the dried solid powder for 2 to 12 hours to obtain the graphene-coated lithium iron phosphate cathode material. The method has the advantages of simple process, high material performance, high conductivity, high bulk density, high compacted density and the like.

Systems, methods, and articles for a portable power case are disclosed. The portable power case is comprised of at least one battery and at least one PCB. The portable power case has at least one USB port and at least two access ports, at least two leads, or at least one access port and at least one lead. The portable power case is operable to supply power to an amplifier, a radio, a wearable battery, a mobile phone, and a tablet. The portable power case is operable to be charged using solar panels, vehicle batteries, AC adapters, non-rechargeable batteries, and generators. The portable power case provides for modularity that allows the user to disassemble and selectively remove the batteries installed within the portable power case housing.

The invention relates to the technical field of lithium iron phosphate production, and discloses a carbon-coated titanium-doped lithium iron phosphate positive electrode material and a preparation method thereof.The preparation method comprises the following steps that 1, a ferrous solution and a phosphorus source solution are mixed in proportion, dopamine hydrochloride is added, a pH regulator is dropwise added in the stirring state, the pH of the solution is adjusted to 4.0-5.5, a reaction is conducted, a titanium source solution is added, and a reaction solution is obtained; after uniformly stirring, continuously dropwise adding a pH regulator to regulate the pH value of the solution to 5.5-6.5; the iron phosphate octahydrate coated with the titanium-embedded polydopamine is obtained; 2) calcining the titanium-embedded polydopamine-coated ferrous phosphate octahydrate in an inert gas atmosphere to obtain carbon-coated titanium-doped anhydrous ferrous phosphate; 3) mixing the carbon-coated titanium-doped anhydrous ferrous phosphate with lithium phosphate and a carbon source, ball-milling, mixing, spray-drying and calcining to obtain a carbon-coated titanium-doped lithium iron phosphate positive electrode material; the synthesis process is simple, and energy consumption is reduced.

The invention belongs to the technical field of battery materials, and particularly relates to a method for preparing a porous carbon structure containing a sub-nanoscale ionic conduction improvement layer by utilizing atomic layer deposition and application. The invention discloses a porous carbon-silicon negative electrode structure, which is characterized in that a sub-nano-scale ion conduction improvement layer is added between a porous carbon substrate and silicon particles, and the sub-nano-scale ion conduction improvement layer comprises silicon carbide, aluminum phosphide, aluminum nitride, aluminum oxide, lithium phosphate, aluminum phosphate and lithium aluminum phosphate. Meanwhile, the invention also discloses a preparation method of the porous carbon-silicon negative electrode structure, namely, a sub-nano-scale ion conduction improvement layer is deposited on the porous carbon substrate through an atomic layer deposition method, so that the binding force between the sub-nano-scale ion conduction improvement layer and silicon particles and an ion transport channel are increased, and the ion conduction of a vapor deposition silicon-carbon negative electrode material is improved; the polarization of the material is effectively reduced, so that the rate capability of the battery is improved, and the cycling stability of the porous carbon structure battery is improved.

The invention provides a lithium ion battery and electric equipment, the lithium ion battery comprises a positive pole piece and an electrolyte, active substances in the positive pole piece comprise a phosphate lithium positive pole material and nickel cobalt manganese lithium oxide, and the electrolyte comprises a positive pole film-forming agent, a negative pole film-forming agent and a lithium salt, the lithium salt comprises lithium hexafluorophosphate and lithium bis (fluorosulfonyl) imide, the lithium ion battery meets the following formula: # imgabs0 #, NL is the mass ratio of the lithium nickel cobalt manganese oxide to the lithium phosphate positive electrode material, Salt is the sum of the molar concentrations of the lithium hexafluorophosphate and the lithium bis (fluorosulfonyl) imide in the electrolyte by taking mol / L as the unit, and the sum of the molar concentrations of the lithium hexafluorophosphate and the lithium bis (fluorosulfonyl) imide in the electrolyte is the sum of the molar concentrations of the lithium hexafluorophosphate and the lithium bis (fluorosulfonyl) imide. Add is the mass ratio of the positive electrode film-forming agent to the negative electrode film-forming agent. When the ternary material is doped in the lithium manganese iron phosphate or the lithium iron phosphate, the proportion of the positive and negative electrode film-forming agents and the proportion of the heat-resistant high-lithium salt can be adjusted according to the mixing proportion of the lithium manganese iron phosphate and the lithium iron phosphate, so that the cycle performance of the battery is improved.

The invention discloses an electrolyte with a temperature switch function and a preparation method and application thereof, and relates to the technical field of lithium ion batteries. The electrolyte provided by the invention comprises the following components: lithium salt, a first organic solvent and a polymer, the lithium salt is at least one of lithium bis (trifluoromethylsulfonyl) imide, lithium bis (fluorosulfonyl) imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium difluoro (oxalato) borate and lithium bis (oxalato) borate; the polymer is polymethacrylate, and the first organic solvent is [Cnmim] [TFSI]. According to the electrolyte, the reversible phase transformation process is realized, the electrode reaction can be closed at high temperature, and the lithium battery is prevented from being out of control due to overheating; and when the temperature is reduced to normal temperature, the battery can work normally. The phase transition temperature of the electrolyte is flexible and controllable, and the phase transition temperature can be regulated and controlled to a reasonable interval by optimizing the composition of the electrolyte and the dosage (concentration) of each component, that is, the phase transition temperature is higher than the normal working temperature of the battery and lower than the initial temperature of the heat release side reaction.

The present disclosure relates to the field of sodium-ion battery technology, and specifically, to a method for preparing carbon-coated sodium iron fluorophosphate from waste lithium iron phosphate and the application thereof. The method for preparing carbon-coated sodium iron fluorophosphate from waste lithium iron phosphate includes: mixing a waste lithium iron phosphate material with an alkaline solution for reaction, followed by solid-liquid separation, to obtain an aluminum-containing filtrate and a lithium iron phosphate filter residue; mixing the lithium iron phosphate filter residue, aluminum chloride and sodium chloride uniformly, followed by vacuum calcination, to obtain a calcination material; and mixing the calcination material with at least one of a sodium source, an iron source and a phosphorus source uniformly to obtain a mixture to which a fluorine source, a carbon source and a solvent are added for uniformly mixing, followed by drying and calcination sequentially to obtain the carbon-coated sodium iron fluorophosphate. The method has the advantages of low costs, a high added value, a short process, and a high recovery rate, and the carbon-coated sodium iron fluorophosphate obtained from the method has excellent electrochemical performance.

A non-aqueous electrolyte for a lithium-ion cell includes a base electrolyte consisting of lithium hexafluorophosphate or lithium bis(fluorosulfonyl)imide or a combination thereof in methyl propionate; about 2 to about 15 parts by weight, preferably about 6 to about 15 parts by weight of vinylene carbonate; and about 0.5 to about 5 parts by weight, preferably about 2 to about 5 parts by weight of an additive comprising lithium difluorophosphate, lithium difluoro(oxalate)borate, lithium bis(oxalate)borate, or a combination thereof, wherein the content of the vinylene carbonate and the additive are each based on a total weight of the base electrolyte, the vinylene carbonate, and the additives.

In one aspect, a preparation method for ferric phosphate includes the following steps: (a) feeding a ferrous sulfate solution and a phosphate solution including hydrogen peroxide simultaneously into a first reactor for mixing and reacting to obtain nucleated ferric phosphate; wherein a molar ratio of iron element to phosphorus element in the feeding process is 1:1, and a stirring speed is 500-600 r / min; (b) discharging the nucleated ferric phosphate to a second reactor for growth to obtain amorphous ferric phosphate slurry, and post-processing the amorphous ferric phosphate slurry to obtain the high tap density ferric phosphate; wherein a stirring speed is 120-150 r / min. The first reactor is a small-volume reactor, and the second reactor is a large-volume reactor.

The invention provides a method for preparing a high-compaction lithium iron phosphate material from hydroxyl iron phosphate, which comprises the following steps: mixing hydroxyl iron phosphate with lithium phosphate, adding a carbon source and an additive, sanding, spray-drying, re-sintering and crushing to obtain particles A; mixing hydroxyl iron phosphate with lithium phosphate, adding a carbon source and an additive, and carrying out ball milling, sanding, spray drying and sintering to obtain particles B; adding a carbon source, a doping agent and a dispersing agent into the particles A, and carrying out ball milling to obtain slurry C; adding a carbon source, a doping agent and a dispersing agent into the particles B, and then carrying out ball milling and sanding to obtain slurry D; uniformly mixing the slurry C and the slurry D according to a certain proportion to obtain mixed slurry E, and then performing spray drying, sintering and crushing to obtain a lithium iron phosphate precursor; and adding a certain amount of carbon source into the lithium iron phosphate precursor, uniformly mixing, sintering and crushing to obtain the high-compaction lithium iron phosphate material.

The invention discloses a method for recovering lithium phosphate from lithium iron phosphate black powder. The method comprises the following steps: mixing black powder recovered from waste lithium iron phosphate batteries with sodium persulfate, and calcining; adding water into the obtained calcined product, dissolving, filtering to obtain water extract A and leaching residues, washing the leaching residues with water, and calcining at high temperature to obtain battery-grade iron phosphate; adding a sodium hydroxide solution into the water extract A, and reacting to obtain a water extract B; adding a trisodium phosphate solution into the water immersion liquid B, fully reacting, performing suction filtration to obtain lithium phosphate and filtrate, and cleaning and drying the lithium phosphate to obtain battery-grade lithium phosphate; and freezing and denitrifying the filtrate to obtain a denitrified solution, and adding the denitrified solution into the sodium hydroxide solution for recycling. The method does not generate wastes, recycles the filtrate in the whole process, theoretically realizes zero loss of the lithium element, prevents the iron element from entering the solution, simplifies the preparation steps of the lithium phosphate, and has the advantages of cost reduction and environmental protection.

The invention discloses a lithium ion battery positive electrode material and a preparation method thereof, the lithium ion battery positive electrode material comprises an active substance, a conductive additive, a binder and a thermal stability additive, the active substance is # imgabs0 # with a layered structure, x + y + z = 1, 0.5 < = x < = 0.8, 0.1 < = y < = 0.3, 0.1 < = z < = 0.3, the conductive additive is a compound of a carbon nanotube and graphene, and the thermal stability additive is a mixture of a carbon nanotube and graphene. The binder is a mixture of polyvinylidene fluoride and sodium carboxymethyl cellulose, the thermal stability additive is a mixture of lithium phosphate and aluminum oxide, the sum of the mass fraction of the lithium phosphate and the mass fraction of the aluminum oxide in the thermal stability additive is 0.5-10%, and the mass fraction of the lithium phosphate is 0.5-5%. According to the lithium ion battery positive electrode material and the preparation method thereof, the stability of the positive electrode material at high temperature can be improved, the thermal runaway risk is reduced, and the cycle life of the battery is prolonged.

The invention discloses a recovery technology for waste lithium iron phosphate batteries, and aims to prepare high-purity iron phosphate and lithium phosphate and comprehensively recover valuable metals such as iron, aluminum and copper in the high-purity iron phosphate and lithium phosphate. The method mainly comprises the following steps that waste lithium iron phosphate battery powder is subjected to oxidizing roasting to obtain roasted battery powder, the roasted battery powder is mixed with phosphoric acid and hydrogen peroxide in different molar ratios, the liquid-solid ratio is adjusted through deionized water, oxidizing leaching is conducted, and lithium-rich liquid and primary leaching residues are obtained; the secondary leaching residues are subjected to phosphoric acid activation, and high-purity iron phosphate dihydrate is obtained after the pH is adjusted; and performing metal ion precipitation on the lithium-rich liquid by adjusting the pH value, and finally performing high-temperature calcination to obtain high-purity lithium phosphate. The method not only realizes efficient leaching and separation of lithium, but also improves the precipitation efficiency of iron phosphate, solves the problems of low metal resource recovery rate and serious process pollution in the prior art, and is suitable for large-scale treatment of waste lithium iron phosphate batteries.

The invention relates to the field of lithium ion batteries, and discloses a positive electrode lithium supplement additive, a preparation method thereof, a positive plate and a lithium ion battery. The lithium supplement additive for the positive electrode comprises a lithium-containing compound, and a first coating layer and a second coating layer which sequentially coat the surface of the lithium-containing compound, wherein the first coating layer comprises at least one of lithium aluminum titanium phosphate, lithium lanthanum zirconium oxide and lithium lanthanum titanium oxide; the second coating layer includes at least one of a Ga-containing compound, a Sm-containing compound, a Si-containing compound, an Al-containing compound, a V-containing compound, a Nb-containing compound, a Mg-containing compound, a Zr-containing compound, and a Zn-containing compound. The first coating layer improves the stability in the processing process, prevents side reaction, ensures the structural stability of the positive electrode lithium supplement additive, and improves the cycle performance of the battery; and the second coating layer provides an effective smooth channel for lithium ions, so that the impedance of the battery can be effectively reduced, and the capacity and the cycle performance of the battery are improved.

The invention provides a negative electrode material, a preparation method thereof and a lithium ion battery, and belongs to the technical field of new energy storage materials. The negative electrode material comprises a phosphorus-carbon carrier and a lithium phosphate covering layer, wherein the lithium phosphate covering layer at least partially covers the surface of the phosphorus-carbon carrier; and compared with the mass of the phosphorus-carbon carrier, the mass content of lithium phosphate in the lithium phosphate covering layer is 0.5-5%. The lithium phosphate covering layer formed by the invention can participate in the formation of a solid electrolyte interface film on the surface of a negative electrode in the cycle process of the battery, prevents the electrolyte from further reacting with a negative electrode material, is beneficial to protecting the electrode, can allow lithium ions to pass through and is beneficial to improving the stability of the battery.

The invention relates to a preparation method of a gel electrolyte with an efficient flame-retardant characteristic. The gel electrolyte is mainly composed of a gel matrix, a flame retardant and an electrolyte solution. The invention provides a method for preparing a flame-retardant gel electrolyte, and application of the flame-retardant gel electrolyte in energy storage equipment such as a lithium ion battery is described in detail. The flame-retardant gel electrolyte has excellent flame retardance, and the safety performance of a battery system can be effectively improved. The preparation method comprises the following specific synthesis steps: (1) firstly, mixing polyethylene oxide (PEO) with a solvent, then adding lithium hexafluorophosphate (LiPF6) electrolyte salt, and uniformly stirring to form a uniform solution; and (2) adding trifluoroethyl methacrylate and a PEGDMA initiator into the solution, carrying out polymerization reaction to form a composite skeleton, and infiltrating the electrolyte under the swelling action to finally form the gel electrolyte. And (3) drying the swelled gel electrolyte to remove redundant solvent and moisture, and then cutting and packaging to obtain the gel electrolyte with high flame retardance. The flame retardance of the electrolyte is remarkably improved by reducing the using amount of the electrolyte and polymerizing and curing the electrolyte.

The invention relates to a battery monomer, a battery device and a power utilization device, the battery monomer comprises an electrode assembly and an electrolyte, the electrode assembly comprises a positive pole piece, the positive pole piece comprises a positive active material layer, and the positive active material layer comprises lithium-containing phosphate of an olivine structure; the electrolyte comprises, by mass, 8-30% of a carboxylic ester solvent, a lithium salt and an unsaturated ester additive, the lithium salt comprises lithium hexafluorophosphate and fluorine-containing lithium sulfimide, the mass content of the fluorine-containing lithium sulfimide in the lithium salt is 18-45%, the mass content of the unsaturated ester additive in the electrolyte is 0.05-5%, and the mass content of the unsaturated ester additive in the electrolyte is 0.05-5%. The unsaturated ester additive comprises one or more of vinylene carbonate, vinylethylene carbonate, allyl ethyl carbonate and a fluoro-carbonate additive; the amount of electrolyte in the battery cell is 2.8 g / Ah to 3.2 g / Ah. According to the invention, rapid charging and use reliability of the single battery can be considered.

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 a positive electrode material and a preparation method thereof, a positive electrode plate and a lithium battery, the positive electrode material comprises a core body and a carbon coating layer, the surface of the core body is at least partially coated with the carbon coating layer, the material of the core body comprises a lithium phosphate positive electrode material, the carbon coating layer contains one or more groups of alkyl, halogen atoms and nitryl. The surface of the lithium phosphate positive electrode material is coated with a layer of carbon material as a protective shell, and the carbon coating layer has hydrophobicity and contains one or more groups of alkyl, halogen atoms and nitryl, so that the prepared positive electrode material has hydrophobicity, the contact between the lithium phosphate positive electrode material and external water is reduced, and the service life of the lithium phosphate positive electrode material is prolonged. The problem of strong water absorption is solved.

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.

The invention discloses a mixed ion conductor layer for a lithium metal negative electrode, a preparation method of the mixed ion conductor layer and an all-solid-state battery, and belongs to the technical field of sulfide all-solid-state batteries. The preparation method comprises the following steps: synthesizing a sulfide electrolyte 70 (0.75 Li2S-0.25 P2S5)-30LiI through a liquid phase, introducing graphene oxide and a lithium salt precursor 2, 5-dihydroxy-1, 4-benzene diphosphate in the electrolyte preparation process, and carrying out heat treatment and pressing to obtain a mixed ion conductor layer; the graphene oxide can isolate the sulfide electrolyte layer from the lithium metal negative electrode, interface reaction is avoided, and a special porous and interlayer structure provides a transverse growth space for lithium metal deposition. And meanwhile, the lithium diphosphate-based MOF among the graphene layers ensures the rapid movement of lithium ions, enhances the bulk diffusion of lithium at the negative electrode end, reduces the local current density, plays a role in dredging the distribution of the lithium ions, and remarkably prolongs the cycle life of the sulfide all-solid-state battery.

The invention discloses a method for comprehensively recovering valuable elements from a waste lithium iron phosphate battery material. The method comprises the following steps: carrying out alkali leaching on black powder and / or pole piece materials of the waste lithium iron phosphate batteries, and then carrying out solid-liquid separation to obtain alkali leaching residues and an alkali leaching solution; carrying out acid leaching on the alkaline leaching residues, and then carrying out solid-liquid separation to obtain an iron oxide powder product and an acid leaching solution; the alkali leaching liquid is cooled and crystallized to obtain a sodium phosphate product and crystallization mother liquor, and the crystallization mother liquor can be circularly used for the alkali leaching process; adjusting the pH value of the acid leaching solution, precipitating and separating to obtain a lithium phosphate product and a lithium precipitation mother solution, wherein the lithium precipitation mother solution can be used for preparing a sodium sulfate product. The method can effectively separate iron, phosphorus and lithium products, and is high in recovery rate, simple, short in process, low in cost and suitable for industrial application.

The invention discloses a silicon-carbon composite negative electrode material, a negative electrode plate, a preparation method and application. The silicon-carbon composite negative electrode material is of a double-coating structure and sequentially comprises inner core silicon, a lithium phosphate layer and a fluorine-containing carbon layer from inside to outside, and the mass ratio of the lithium phosphate layer to the inner core silicon is (1-5): 100. When the composite material is applied to a lithium ion battery, the core silicon and the specific double coating layers can improve the fast charging performance and the first effect while optimizing an ion transmission path; a specific double-coating structure can be used as a buffer layer, stress generated by volume expansion of silicon can be released, and pulverization of particles is avoided; and moreover, LiF with high ionic conductivity and higher mechanical strength and an SEI film with more stable regulation and control are formed through reaction with an electrolyte, so that the structural integrity of the material is kept, and the cycle performance of the material is improved.

Provided according to exemplary embodiments is a lithium secondary battery comprising: a positive electrode containing a lithium iron phosphate; and an electrolyte containing a compound represented by chemical formula 1. The lithium secondary battery can have enhanced high-temperature cycle characteristics and low resistance characteristics. The lithium secondary battery can have enhanced high-temperature cycle characteristics and low resistance characteristics.

A lithium manganese iron phosphate substrate, cathode material, and their preparation method, as well as a lithium battery, belonging to the field of lithium-ion battery technology. The preparation of the lithium manganese iron phosphate substrate comprises the following steps: dissolving soluble ferrous salt, soluble manganese salt, phosphoric acid, and lithium hydroxide in deionized water to react, obtaining Material A; filtering Material A, taking the filter cake and drying it to obtain Material B; Heat treating Material B in an inert gas atmosphere to obtain the lithium manganese iron phosphate substrate. By coating the surface of the carbon-free nano lithium manganese iron phosphate substrate with metal oxides or metal salts and carbon, the coating layer formed on the surface of the composite lithium manganese iron phosphate material effectively prevents the reaction between the lithium battery and the electrolyte.

The invention discloses a lithium hexafluorophosphate production control system and a method thereof, and relates to the technical field of lithium hexafluorophosphate production, and the method specifically comprises the following steps: obtaining crystallization dynamic information of each area in a reaction kettle in a lithium hexafluorophosphate crystallization process in real time, and analyzing after obtaining to obtain a crystallization dynamic result; respectively generating a crystal growth driving force coefficient and a particle uniform distribution index of each region; constructing a particle size distribution evaluation model for the generated crystal growth driving force coefficient and particle uniform distribution index of each region, generating a particle size distribution coefficient of each region, and performing comprehensive analysis after generation to generate an evaluation coefficient; and analyzing the generated evaluation coefficient, and evaluating the uniformity degree of particle size distribution in the reaction kettle in the lithium hexafluorophosphate crystallization process. The problem of uneven particle size distribution in the lithium hexafluorophosphate crystallization process is solved, and the effect of improving the particle size uniformity and the product quality stability is achieved.

The present disclosure provides a composite solid electrolyte. The composite solid electrolyte includes a lithium lanthanum zirconium oxide particle and a protective layer containing lithium phosphate. An average particle size of the lithium lanthanum zirconium oxide particle is smaller than 500 nm and larger than 50 nm. The protective layer containing lithium phosphate covers an outer surface of the lithium lanthanum zirconium oxide particle.

The invention provides a composite diaphragm, a preparation method thereof and a lithium ion battery. The composite diaphragm comprises a base diaphragm and a solid electrolyte-water-soluble gel electrolyte composite coating, wherein the surface of the base diaphragm is coated with the solid electrolyte-water-soluble gel electrolyte composite coating by utilizing a roller coating process; the water-soluble gel electrolyte is obtained by co-polymerizing an intermediate I prepared from methyl methacrylate and N-isopropylacrylamide and neopentyl glycol diglycidyl ether. In the composite diaphragm provided by the invention, the water-soluble gel electrolyte can effectively improve the adhesion of the solid electrolyte on the base membrane, and ensure that the solid electrolyte can be effectively adhered to the surface of the base membrane; lithium titanium aluminum phosphate and the like can effectively promote transmission of lithium ions through the solid electrolyte, the hexagonal boron nitride composite coating can prevent direct contact between the lithium titanium aluminum phosphate solid electrolyte and the like and lithium, and the solid electrolyte is protected. And the interface stability of the composite diaphragm is relatively good, and a compact phase formed in the circulation process can effectively inhibit the permeation of lithium dendrites, so that the safety of the battery is improved.

The invention discloses a ternary positive electrode material, a preparation method thereof and an electrochemical device. The preparation method comprises the following steps: mixing a continuous ternary precursor, a lithium source and an aluminum source, and carrying out first sintering to obtain a first sintered product; the primary sintering product is subjected to secondary sintering and dispersion, a single-crystal base material is obtained, the base material comprises a plurality of primary particles, the average size of the primary particles ranges from 2 micrometers to 3 micrometers, and the median particle size Dv50 of the primary particles ranges from 3 micrometers to 5 micrometers; mixing the matrix material with an aqueous solution of lithium phosphate, and carrying out wet coating to obtain a coated product; and sintering the coated product for the third time, so that the lithium phosphate forms a coating layer on the surface of the matrix material, and the ternary positive electrode material is obtained. According to the invention, through two-parameter control of the average size and the median particle size of the matrix material and simultaneous aluminum element internal doping and lithium phosphate surface coating of the matrix material, the structural stability and the cycle performance of the ternary positive electrode material are improved and the service life of the ternary positive electrode material is prolonged through a synergistic effect.

The invention relates to a method for treating a waste iron phosphate positive electrode material by a phosphoric acid-hydrogen peroxide method matched with a specific complexing agent. The method comprises the following steps: crushing the positive electrode material of the waste lithium iron phosphate battery, adding the crushed positive electrode material into deionized water, and stirring to prepare slurry; heating the slurry, dropwise adding a phosphoric acid-hydrogen peroxide mixed solution and a complexing agent, adding a NaOH solution to adjust the pH value to 3.5, and filtering to obtain a filtrate and a filter cake; adding a NaOH solution into the filtrate, and adjusting the pH value to 10 to obtain lithium phosphate; performing evaporative crystallization on the filter cake to obtain trisodium phosphate; the complexing agent is prepared by adding pentasodium salt of amino trimethylene phosphonic acid, triallyl citrate, epoxysuccinic acid and DMF (Dimethyl Formamide) into a reaction kettle, mixing, adding ammonia water to adjust the pH value to be 10, and distilling to remove the DMF after the reaction is finished. The precipitation rate of Fe reaches up to 99.99%, the leaching rate of Li reaches up to 99.91%, and efficient separation and recycling of lithium and iron are achieved.