846results about "From solid state" patented technology

The invention provides a preferred orientation single crystal lithium-rich manganese-based positive electrode material, a preparation method thereof and a lithium ion battery, and relates to the technical field of battery positive electrode material preparation. The lithium-rich manganese-based positive electrode material is in a single crystal morphology, and in a diffraction pattern obtained by adopting an XRD (X-Ray Diffraction) instrument taking Cu K alpha as an incident light source, the peak intensity ratio I (003) / I (104) gt of a (003) peak of which 2 theta is positioned at 18.6 + / -0.1 degrees to a (104) peak of which 2 theta is positioned at 44 + / -0.5 degrees; 2. The single crystal lithium-rich manganese-based material with the specific crystal face preferentially growing is prepared, the material preferentially grows along the (003) crystal face by regulating and controlling the synthesis process of the material, the electrochemical performance of the material can be remarkably improved, and especially the stability under the high-rate charging and discharging condition can be remarkably improved.

The invention belongs to the technical field of lithium batteries, and discloses a lithium nickel manganese oxide positive electrode material, a preparation method thereof and a lithium ion battery. Wherein the lithium nickel manganese oxide positive electrode material has a regular truncated octahedron single crystal structure, and the ratio K of a (111) crystal face orientation parameter to a (100) crystal face orientation parameter in an XRD (X-Ray Diffraction) spectrogram of the lithium nickel manganese oxide positive electrode material is 1-1.6. The lithium nickel manganese oxide positive electrode material provided by the invention has excellent rate capability and cycling stability, and can be well applied to production and manufacturing of lithium ion batteries.

The invention belongs to the technical field of whisker material growth and ceramic substrate preparation, and discloses a preparation method of an aluminum nitride whisker and a high-strength and high-thermal-conductivity ceramic substrate, and the preparation method of the aluminum nitride whisker comprises the following steps: mixing aluminum powder serving as a raw material and ammonium salt serving as an inducer according to a mass ratio of (2: 1)-(1: 2); and carrying out heat preservation for 0.5-2 hours at the temperature of 800-1100 DEG C under the nitrogen and / or ammonia atmosphere condition, and carrying out nitridation reaction. According to the invention, a whisker and ceramic substrate synthesis method is improved, aluminum nitride whiskers with uniform morphology and length-diameter ratio are controllably synthesized through a rapid nitriding method, and the aluminum nitride whiskers and spherical aluminum nitride are sintered only by taking the aluminum nitride whiskers as an additive without the participation of additional sintering aids and reinforcers, so that the ceramic substrate is obtained. The high-strength and high-thermal-conductivity aluminum nitride ceramic substrate is obtained and has high mechanical strength and thermal conductivity.

The invention provides an ultrahigh-nickel single-crystal positive electrode material and a preparation method and application thereof.The ultrahigh-nickel single-crystal positive electrode material comprises fluxing agent doping elements and high-valence doping elements, the fluxing agent doping elements comprise Zr, Ce, Sr, Y, La, Sn or Na, and the high-valence doping elements comprise Sb, W, Nb, Ta, Mo, Ti or P; the doping amount of the fluxing agent doping element is omega A, the doping amount of the high-valence doping element is omega B, and omega A and omega B meet the following relational expression: 0.5 < 0.746 * exp [-omega B / (0.891 * omega A)] + 0.556 < 1.0. Omega A and Omega B meet a specific relational expression, two doping elements are effectively promoted to play a role, a small-particle-size and uniformly-dispersed single crystal is formed, the material has high stability and safety of the single crystal, a Li < + > diffusion path can be shortened, dynamics can be improved, and the advantage of high capacity can be achieved.

A method of synthesis of single crystal nickel-rich cathode materials can include preparing a precursor solution by dissolving lithium nitrate, nickel nitrate, manganese nitrate, and cobalt nitrate in water, aerosolizing the solution of a) in a stream of air using an ultrasonic sprayer, preheating the resulting droplets, premixing the droplets with methane, decomposing the droplets by passing through a co-flow burner, depositing solid particles on a filter, and calcinating the solid particles in a furnace in oxygen to produce a single crystal cathode material.

The invention relates to a compound selenium-indium-cesium and a selenium-indium-cesium infrared nonlinear optical crystal as well as a preparation method and application thereof. The molecular formula of the compound is CsIn5Se8, the molecular weight is 1338.69, the molecular formula of the crystal is CsIn5Se8, the molecular weight is 1338.69, the structure has an asymmetric center and belongs to a triclinic system, the space group is P1, and the cell parameters are as follows: a is 9.1506 (3), b is 9.1793 (3), c is 11.2778 (3), alpha is 89.9560 (10) degrees, beta is 72.0140 (10) degrees, gamma is 72.0340 (10) degrees, Z is 2, and the volume is 852.38 (5) 3. The crystal is prepared by adopting a high-temperature melt method, a chemical vapor transport method, a Bridgman-Stockbarger method or a fluxing agent method. The obtained selenium-indium-cesium infrared nonlinear optical crystal has the advantages of large nonlinear optical response, good crystal growth habit, good mechanical property, difficulty in fragmentation and deliquescence, easiness in processing and storage and the like, and can be used for manufacturing infrared nonlinear optical devices; the method has important application in the fields of photoelectric countermeasure, spectrum technology, laser communication, remote sensing distance measurement and the like.

The invention provides a method for preparing beta-SiC containing a whisker structure from rice husks, and belongs to the field of comprehensive utilization of resources and inorganic non-metallic materials. The method comprises the following steps: carbonizing rice hulls in a protective atmosphere to obtain rice hull ash, removing impurities from the rice hull ash, and fully mixing the rice hull ash with NaCl and H3BO3 to obtain a rice hull ash mixture; and putting the two groups of rice hull ash mixtures into the same atmosphere furnace, introducing shielding gas, enabling the gas to sequentially pass through the H3BO3 mixture and the NaCl mixture in sequence, heating to 1300-1600 DEG C at a heating rate of 2-10 DEG C / min, performing high-temperature treatment for 1-5 hours, washing and drying the obtained solid, and firing in air to obtain beta-SiC. The silicon carbide product with high commercial value is prepared from the cheap rice hulls, hydrofluoric acid and other high-toxicity and high-corrosivity raw materials are not needed in the preparation process, the heat treatment temperature is low, large-scale production can be easily achieved, the problems that an existing industrial carbon thermal reduction method is large in process pollution and high in energy consumption can be solved, the production cost is reduced, and the method is suitable for industrial production. And industrial popularization and application are facilitated.

The invention relates to an indium phosphide crystal containing doped elements, a single crystal wafer and a preparation method of the indium phosphide crystal. Specifically, the invention relates to an indium phosphide crystal containing a doped element, the doped element is doped in an indium phosphide crystal growth melt or in indium phosphide polycrystalline material synthesis, and the indium phosphide crystal is an S-doped or Sn-doped N-type indium phosphide single crystal or a Zn-doped P-type indium phosphide single crystal. The doped element is one or more elements, and the segregation coefficient of the doped element in indium phosphide is not greater than 0.05; and the content of the doped element in the indium phosphide crystal is 30 ppb to 30 ppm. The invention also relates to a method for preparing the indium phosphide crystal containing the doped elements, a method for preparing a single crystal wafer and a device prepared from the indium phosphide single crystal. The indium phosphide crystal containing the doped elements obtained according to the invention is high in single crystal yield.

The invention provides a preparation method of magnesium niobate, which comprises the following steps: carrying out wet ball milling on MgO and Nb2O5, uniformly mixing, and drying to obtain mixed powder; the mixed powder is heated to 1500-1700 DEG C for 1-3 h and then subjected to water quenching, and solid particles of a core-shell structure inclusion are obtained; and heating the solid particles to 1000-1200 DEG C, and carrying out heat preservation to obtain the magnesium niobate. Solid particles of a core-shell structure inclusion are formed through a water quenching process, then MN obtained through rapid heating sintering is high in purity and stability, Mg < 2 + > and Nb < 5 + > in the MN are high in uniformity and large in reaction activity, sufficient mixing with PbO and TiO2 at a high temperature is facilitated to form a liquid phase, the formed raw material for PMNT crystal growth is better in singleness and uniformity, and the preparation method is simple and easy to implement. Furthermore, the PMNT single crystal with a single perovskite structure, high purity and excellent piezoelectric property can be obtained, and the yield is improved.

The invention provides a method for preparing a perovskite thin film, and the method comprises the steps: dividing the surface of a perovskite thin film spin-coated on a substrate into a plurality of corresponding regions according to the thickness, carrying out the irradiation of each region through employing a first laser with a corresponding wavelength and a fixed light spot size, so as to generate a uniformly-distributed seed crystal array, and scanning each region by adopting second laser with corresponding wavelength to enable the surface temperature of each region to reach a specified temperature range, and ensuring that the temperature difference between each seed crystal region and the periphery is within a preset range to enlarge the crystal size of the seed crystal and improve the crystal uniformity of the perovskite thin film. And finally, the surface temperature of the perovskite thin film is slowly reduced through a temperature control system, so that the crystallization uniformity is further improved, and grain segregation caused by thermal stress and thermal gradient is reduced. According to the technical scheme provided by the invention, the uniformity and the size moderation of the perovskite thin film crystal can be considered, the defects are reduced, and the photoelectric conversion and transmission performance of the perovskite cell is improved.

The present invention provides a single-crystal lithium-rich manganese-based positive electrode precursor and its preparation method and application. The single-crystal lithium-rich manganese-based positive electrode precursor comprises secondary particles formed by primary particles and satisfies the following relationship: 1.2μm≤D50≤1.8μm, 0.5μm≤D R <6.0μm, 0.5g / cm 3 ≤α≤0.8g / cm 3 , 30m 2 / g≤β≤50m 2 / g, 22≤α·β≤28, 20nm≤N≤45nm, 5≤M / N≤10, wherein D50 is the median particle size of the secondary particles, D R is the particle size of the secondary particles, α is the tap density of the secondary particles, β is the specific surface area of ​​the secondary particles, N is the average thickness of the primary particles, and M is the average length of the primary particles. The median particle size of the secondary particles of the single-crystal-like lithium-rich manganese-based positive electrode precursor provided by the present invention is no more than 1.8 μm, which is significantly lower than the reported particle size of (quasi) single-crystal lithium-rich positive electrode precursors. The precursor can be made into a submicron-level single-crystal-like lithium-rich manganese-based positive electrode material with excellent dispersibility.

The invention relates to the technical field of new energy, and discloses a single-crystal positive electrode material which comprises a core layer and a first shell layer, the core layer is a ternary material core layer doped with a metal element A; the first shell layer is a fluoride coating layer; the metal element A is selected from at least one of zirconium, titanium, magnesium, aluminum, niobium and tungsten; the fluoride coating layer is obtained by doping villiaumite containing a metal element A into the core layer, sintering and migrating to the surface of the ternary material core layer; through the design, the cycling stability of the positive electrode material is improved from two aspects of improving the internal structure stability of the positive electrode material and consuming residual lithium on the surface, and meanwhile, due to doping of the metal element A and the villiaumite containing the metal element A, the metal element A is more uniformly distributed in the positive electrode material, so that the stability of the material is further improved; in addition, the invention also discloses a single-crystal positive electrode material.

The invention discloses a preparation method of calcite type calcium carbonate whiskers, which comprises the following steps: (1) preparing a calcium hydroxide suspension, and heating the calcium hydroxide suspension to obtain a hot calcium hydroxide suspension for later use; (2) adding a seed crystal and a crystal form control agent into the hot calcium hydroxide suspension, and uniformly stirring to obtain a hot mixed suspension; (3) continuously introducing carbon dioxide into the hot mixed suspension liquid for reaction until the reaction is finished, stopping introducing the carbon dioxide to obtain a calcium carbonate suspension liquid, filtering and drying to obtain calcium carbonate powder; and (4) calcining the calcium carbonate powder in a furnace, and crushing to obtain the calcite type calcium carbonate whisker. The calcium carbonate whisker prepared by the method is calcite type, and a new research thought is provided for preparation of the calcite type calcium carbonate whisker; the calcite calcium carbonate whisker prepared by the method is the most stable phase of calcium carbonate, and the application field of the calcium carbonate whisker is expanded.

The invention relates to a nano silicon carbide whisker and a preparation method thereof, and the preparation method comprises the following steps: (1) carrying out acid process treatment on fly ash by using an acid solution, so that the content of key impurity elements in the fly ash accounts for 2-11% of the total mass of the treated fly ash, and obtaining acid-treated fly ash; (2) mixing the acid-treated fly ash with a first carbon source to obtain a mixture; and (3) covering the mixture with a second carbon source, roasting in a reducing atmosphere to obtain a roasted material which comprises a nano silicon carbide whisker layer and a total impurity layer positioned below the silicon carbide whisker layer, and removing the total impurity layer to obtain the nano silicon carbide whisker. According to the preparation method, the low-cost fly ash is taken as a raw material, the advantages of low preparation cost and relatively high product yield can be taken into account through the synergistic effect of moderate acid treatment, raw material position setting and roasting in the reducing atmosphere, and good morphology and relatively high purity of the nano silicon carbide crystal whiskers are ensured.

The invention discloses a preparation method of a perovskite thin film and a perovskite cell, and relates to the technical field of solar cells. The preparation method of the perovskite thin film comprises the following steps: forming a mixed layer containing PbI2 on a substrate as a metal halide framework layer; coating the metal halide framework layer with an organic ammonium salt solution containing a crystallization regulating agent to obtain a first device; wherein the crystallization regulating agent contains a guanidine group; and carrying out annealing treatment on the first device to obtain the perovskite thin film. According to the perovskite thin film, the problems that perovskite prepared in the prior art is small in grain size and uneven in interface can be solved, and the performance of the perovskite thin film is improved.

The invention belongs to the field of positive electrode materials, and particularly relates to a molybdenum and titanium doped single crystal positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: S1, mixing a nickel source, a cobalt source, a manganese source, a molybdenum source, a titanium source and water to obtain a mixed solution, and adding a pH regulator for precipitation reaction to obtain a precursor; wherein the molar weights of nickel, cobalt, manganese, molybdenum and titanium are x, y, z, a and b respectively; x is more than or equal to 0.90% and less than or equal to 0.95%, y is more than or equal to 0.02% and less than or equal to 0.08%, z is more than or equal to 0.01% and less than or equal to 0.08%, a is more than or equal to 0.004% and less than or equal to 0.012%, b is more than or equal to 0.001% and less than or equal to 0.006%, and x + y + z + a + b is 100%; and S2, mixing a lithium source and the precursor, sintering, and crushing to obtain the molybdenum and titanium doped single crystal positive electrode material. The battery containing the positive electrode material has excellent discharge capacity, rate capability and cycle life.

The invention belongs to the technical field of lithium ion battery materials, and discloses a preparation method of a high-first-effect small-particle single-crystal ultrahigh-nickel ternary positive electrode material. The method comprises the following steps: firstly, uniformly mixing an ultrahigh nickel ternary precursor with a lithium source and a tungsten source, performing mechanical densification and pressing to obtain a blocky solid, and then performing four-section program temperature control calcination to obtain a target material. The interface fusion resistance of single crystal growth can be reduced through mechanical densification; a part of the tungsten element forms a Li2WO4 coating layer, and a part of the dopant phase replaces Ni < 2 + >, so that grain growth can be inhibited, a crystal structure can be stabilized, and the first effect is improved; and the microstructure of the material can be accurately regulated and controlled through four-section temperature-controlled calcination. Through a coating-doping-single crystallization synergistic strategy, the electrochemical performance of the material in liquid and sulfide-based all-solid-state batteries is remarkably improved, the process is controllable, and the application prospect is wide.

A silicon carbide seed is provided, including a first seed layer and a second seed layer. The first seed layer includes a polycrystalline silicon carbide material. The second seed layer is directly attached to the first seed layer, where the second seed layer includes a single crystal silicon carbide material, and a thickness ratio (T2 / T1) of a thickness T1 of the first seed layer to a thickness T2 of the second seed layer is in a range of 10% to 50%.

The invention provides a ternary single-crystal positive electrode material as well as a preparation method and application thereof. The D50 of the ternary single-crystal positive electrode material is greater than or equal to 3 microns; dO-Li-O of the ternary single crystal positive electrode material is equal to 2.0 A to 3.5 A, and dO-Li-O is the distance between Li atoms and O atoms of two adjacent layers; the compression strength of the ternary single crystal positive electrode material is greater than or equal to 150MPa. The ternary single-crystal positive electrode material provided by the invention is relatively good in rate capability and cycle performance.

The invention discloses a metal-free catalyst ZrC whisker as well as a preparation method and application thereof, and belongs to the technical field of ultrahigh-temperature ceramic materials. The preparation method comprises the following steps: dissolving a zirconium source and sodium fluoride in N-N, dimethylformamide to prepare a metal salt solution; adding a carbon source into the metal salt solution to obtain a spinning precursor solution; wherein the carbon source is simultaneously used as a carbon source and a spinning auxiliary agent, and the carbon source is polyacrylonitrile or polyvinylpyrrolidone; carrying out electrostatic spinning by adopting the spinning precursor solution to obtain a primary spun yarn; and carrying out high-temperature carbonization on the initial spinning yarns to obtain the ZrC crystal whiskers. As no metal catalyst is used, the ZrC whisker prepared by the method is free of impurities and high in purity, and large-scale and simple preparation of the ZrC whisker can be realized.

The invention discloses a high-voltage single-crystal positive electrode material as well as a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The preparation method comprises the following steps: by taking MOFs (Metal Organic Frameworks) with a porous structure as a template, loading a ternary precursor in pore channels of the template by adopting a solvothermal method to prepare loaded MOFs; mixing the loaded MOFs with a lithium source, carbonizing and calcining in an inert atmosphere for high-temperature solid-phase reaction, carbonizing the template to form a nitrogen-doped porous carbon skeleton, and converting the ternary precursor into single-crystal NCM particles to prepare a calcined product; sequentially carrying out acid pickling, drying and airflow crushing treatment on the calcined product to obtain a composite material; the composite material is sequentially subjected to multi-section penetration type dry coating and sintering treatment, the high-voltage single-crystal positive electrode material is prepared, and the high-voltage single-crystal positive electrode material can balance the capacity, the cycle life and the safety under high voltage.

The invention discloses a method for regulating and controlling the size of a cobalt-free single crystal lithium-rich manganese-based positive electrode material, which comprises the following steps of: firstly, preparing a cobalt-free lithium-rich positive electrode material precursor from manganese salt and nickel salt by adopting a solid phase method or a coprecipitation method, then uniformly mixing the cobalt-free lithium-rich positive electrode material precursor, a lithium source and mixed salt of chloride salt and fluoride salt, and then preparing the cobalt-free single crystal lithium-rich manganese-based positive electrode material. The preparation method comprises the following steps: carrying out primary calcination at the temperature of 280-550 DEG C, then carrying out secondary calcination at the temperature of 600-800 DEG C, further heating, and then carrying out tertiary calcination at the temperature of 900-1100 DEG C, so as to obtain the cobalt-free single crystal lithium-rich manganese-based positive electrode material after the calcination is finished. The method provided by the invention realizes regulation and control of the size of the cobalt-free single crystal lithium-rich manganese-based positive electrode material; therefore, the cobalt-free single crystal lithium-rich manganese-based positive electrode material with high specific capacity and cycle performance is obtained.

The invention provides a preparation method of an N and metal co-doped p-type gallium oxide film, and belongs to the technical field of semiconductor materials. The N-doped gallium oxide thin film is obtained by annealing an unintentionally doped silicon-based GaN epitaxial wafer in an oxygen atmosphere. A layer of metal is uniformly distributed on the surface of the N-doped gallium oxide thin film, and then the N-doped gallium oxide thin film is placed in an anoxic environment to be annealed to obtain the N and metal co-doped p-type gallium oxide thin film. The method is simple to operate, and the hole concentration of the prepared N and metal co-doped p-type gallium oxide thin film reaches 1 * 10 < 11 > cm <-3 >-1 * 10 < 19 > cm <-3 >.

The invention relates to a preparation method and application of a 2D / 2D heterostructure wave-absorbing material based on solvent regulation and control growth, and belongs to the technical field of preparation of wave-absorbing materials. The preparation method comprises the following steps: constructing 2D tabular Bi4NbO8Cl which mainly exposes {001} and {110} high-activity crystal faces through a crystal face engineering technology, and further performing in-situ growth of a 2D ZnIn2S4 nanosheet on the surface of Bi4NbO8Cl, thereby obtaining the ZnIn2S4 / Bi4NbO8Cl composite wave-absorbing material. Under MW driving, the material shows ultrahigh catalytic degradation activity on OTC, and has potential application prospects in the aspect of purification of environmental water bodies polluted by antibiotics.

The invention provides a positive electrode material and a preparation method thereof, a positive electrode plate and a battery, the positive electrode material comprises a positive electrode active material, and the positive electrode active material comprises a ternary single crystal material and lithium ferric manganese phosphate; the crystal lattice spacing a1 of the crystal of the ternary single crystal material is equal to b1, the range of the crystal lattice spacing a1 is # imgabs 0 #, the range of the crystal lattice spacing c1 is # imgabs 1 #, the crystal lattice spacing a2 of the crystal of the lithium iron manganese phosphate is equal to b2, and the range of the crystal lattice spacing a2 is # imgabs 2 #, and the range of the crystal lattice spacing c2 is # imgabs 3 #. The stability and conductivity of the positive electrode material can be improved, so that the charge-discharge efficiency of the battery is improved.

The present description belongs to the technical field of battery materials. Disclosed are a single-crystal ternary positive electrode material, a preparation method therefor, a positive electrode sheet and a battery. The apparent factor of the single-crystal ternary positive electrode material is [Formula 1], wherein 1.1≤Z≤3, x=D90 / D10, 2≤x≤5; S(D90) is the number averaged circularity, the total number of target particles is n, and the number averaged circularity is defined as the sum of circularity values of all of the target particles divided by n. The area and circumference corresponding to a two-dimensional projection image of a single target particle are respectively S1 and l1, the circumference of a circle having the area S1 is l2}, and the circularity = l2 / l1. The D10' is the corresponding particle size of a material obtained by compacting the single-crystal ternary positive electrode material at 200 MPa, D10 does not exceed 2.4 μm, and D10' does not exceed 2.3 μm. The single-crystal ternary positive electrode material has smooth surfaces and rounded edges, which are beneficial for fabricating batteries having excellent electrochemical properties.

A cathode material precursor, a single-crystal cathode material and a preparation method thereof, and a lithium ion battery are provided. A general chemical formula of the single-crystal cathode material is LixNiaCobMncNdO2, where 0.98≤x≤1.1, 0.50≤a≤0.98, 0<b≤0.20, 0<c≤0.30, 0≤d≤0.10, a+b+c+d=1, and N includes at least one of Al, Ti, Zr, Mg, Sr, Ba, Ca, Nb, W, Sb, Ta, Sn, or Y; a standard deviation of a mass content of each element of Ni, Co, and Mn in the single-crystal cathode material is ≤0.03; and lattice strain is ε<0.2%.

The invention relates to a method for preparing a single-crystal lithium-rich manganese-based positive electrode material by synergistically regulating and controlling a deep eutectic solvent and aluminum gradient doping, which comprises the following steps of: carrying out multi-stage aluminum gradient doping to prepare a single-crystal lithium-rich manganese-based positive electrode material by synergistically regulating and controlling the deep eutectic solvent and the aluminum gradient doping; multi-level regulation and control on the structure of the positive electrode material from the inside to the surface are realized; the formation of an inducible single-crystal structure is assisted by the deep eutectic solvent; through addition of phosphorus / boron-containing anions and microwave strengthening treatment, oxygen vacancy lattice repair is promoted; carbon in-situ coating treatment is realized by adding a carbon source, so that the conductivity and interface stability of the material are improved; and lithium defects caused by other steps can be compensated through pre-lithiation treatment, and the first coulombic efficiency is improved. And five parts are integrated, so that the structural stability, the electrochemical performance and the safety of the material are multiply improved.

The invention provides a single-crystal cobalt-free lithium-rich manganese-based positive electrode material as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a cobalt-free lithium-rich manganese-based precursor material, a lithium source and a grain boundary separation auxiliary agent to obtain a mixed material; the mixed material is subjected to two-stage sintering, the two-stage sintering comprises first sintering and second sintering in sequence, and the single-crystal cobalt-free lithium-rich manganese-based positive electrode material is obtained, wherein primary crystal grains of the cobalt-free lithium-rich manganese-based precursor material are of a sheet structure. According to the invention, the cobalt-free lithium-rich manganese-based precursor material of which the primary crystal grains are of a sheet structure is taken as a raw material, and under the action of the grain boundary separation auxiliary agent, a two-stage sintering process is cooperatively matched, so that the single-crystal cobalt-free lithium-rich manganese-based positive electrode material which is uniform in grain size, high in dispersity, complete in crystal grains and continuous in interface is obtained, and the cobalt-free lithium-rich manganese-based positive electrode material is not only suitable for a liquid lithium ion battery, but also suitable for a lithium ion battery. The material is more suitable for a solid-state lithium ion battery, and the electrochemical performance of the battery is effectively improved.

The invention belongs to the technical field of positive electrode active materials, and particularly relates to nano single crystal lithium iron phosphate as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out ball milling on a mixture containing a lithium source, an iron source and a phosphorus source in a supercritical fluid, and carrying out roasting, impurity removal and drying treatment to obtain lithium iron phosphate, and dispersing the lithium iron phosphate in glycerol, and sintering to obtain the nano single crystal lithium iron phosphate. According to the preparation method of the nano single crystal lithium iron phosphate, a supercritical fluid technology and secondary sintering are combined, so that carbon coating on the surface of the lithium iron phosphate is uniform, the grain size of lithium iron phosphate grains is refined, and the electron transmission rate and the cycling stability of the lithium iron phosphate are further improved.