CN115394976A - Preparation method and application of positive electrode material - Google Patents
Preparation method and application of positive electrode material Download PDFInfo
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- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
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Abstract
The invention discloses a preparation method and application of a positive electrode material, which comprises the following steps: s1, dispersing a manganese source, an iron source, a lithium source and a phosphorus source, crushing and drying; s2, performing microwave plasma chemical vapor deposition treatment on the powder obtained after drying in the step S1; obtaining a lithium manganese iron phosphate material after the heat treatment; and S3, carrying out carbon coating on the powder subjected to the plasma treatment in the step S2 and then crushing the powder. The invention can prepare Li capable of improving lithium manganese iron phosphate + A diffusion rate and an electronic conductivity.
Description
Technical Field
The invention belongs to the technical field of new energy materials, and particularly relates to a preparation method and application of a positive electrode material.
Background
Because of having higher working voltage and excellent cycle performance, the lithium ion battery is widely applied to the fields of new energy automobiles, mobile equipment, energy storage power stations and the like. With the continuous development of the technology, people also put forward higher requirements on the lithium ion battery, and the design and development of electrode materials with higher capacity, high power, high energy density and good cycle stability have become one of the research hotspots in the field of new energy.
Lithium iron phosphate (LFP) of olivine-type structure is mainly used in lithium ion batteries, batteries of electric/hybrid vehicles or energy storage power stations, however, low charge/discharge voltage plateau (3.4V) results in low energy density, which limits its development in the field of energy storage. Compared with LFP, the lithium manganese iron phosphate (LMFP) anode material has high discharge voltage (two platforms of 3.4V and 4.1V) and the energy density is 20% higher than that of LFP. The crystal structure of the LMFP is similar to that of the LFP and is an olivine structure, and the theoretical specific capacity is 170mAh g -1 . The electrochemical performance of LMFP is limited by electron transport and ion diffusion, PO 4 3- The medium and strong P-O covalent bond stabilizes oxygen atoms and ensures Li + Can be embedded/separated in a stable crystal structure, and the olivine-type LMFP structure shows good safety and cycling stability. However, LMFP is a semiconductor compound with very low electron conductivity because M-O (M = Fe, mn) octahedra are separated by P-O tetrahedra, no continuous M-O network is formed in its crystal structure, and in addition, the strong P-O covalent bond also prevents Li from being formed + By PO 4 3- Tetrahedra, li + The transport of (A) can only be a one-dimensional diffusion along the b-axis, which reduces Li + Resulting in poor conductivity.
Therefore, how to further improve Li in lithium manganese iron phosphate + The diffusion rate and the electronic conductivity of (2) are currently urgent matters.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a preparation method of a cathode material, which can prepare Li for improving lithium manganese iron phosphate + Positive electrode of diffusion rate and electronic conductivityA material.
The invention also provides application of the cathode material prepared by the preparation method of the cathode material in preparation of a secondary battery.
A method for producing a positive electrode material according to an embodiment of the first aspect of the invention includes the steps of:
s1, mixing and dispersing a manganese source, an iron source, a lithium source and a phosphorus source, crushing and drying;
s2, carrying out heat treatment on the powder obtained after drying in the step S1, wherein the heat treatment is carried out in a microwave plasma environment;
obtaining a lithium manganese iron phosphate material after the vapor deposition treatment;
s3, carrying out carbon coating on the powder obtained in the step S2 and then crushing the powder; the carbon coating method is a microwave plasma chemical vapor deposition method.
The preparation method of the cathode material provided by the embodiment of the invention has at least the following beneficial effects:
1. the carbon layer deposited by the Microwave Plasma Chemical Vapor Deposition (MPCVD) method in the step S3 not only protects the positive pole piece coated with carbon from being corroded by electrolyte, but also improves the electronic conductivity due to the higher graphitization degree of the positive pole material, and finally improves the electrochemical performance of the obtained positive pole material.
2. The carbon-coated lithium manganese iron phosphate synthesized by the MPCVD method has controllable particle size, overcomes the growth and agglomeration of particles of the material under high-temperature calcination and improves the specific capacity and the cycling stability of the material compared with the conventional nitrogen atmosphere sintering.
3. The method is an effective means for improving the electrochemical performance of the electrode material by coating a layer of carbon on the surface of the lithium ferric manganese phosphate material. On the one hand, the carbon layer is present between the particles, which may enhance the conductivity of the material, so that the polarization is reduced; on the other hand, the carbon layer can also provide more rapid tunnels for electron transmission, and the carbon coating can inhibit the growth of crystal grains, so that the movement distance of lithium ions can be shortened, and the rate capability of the lithium manganese iron phosphate active material can be improved.
According to some embodiments of the invention, the manganese source comprises at least one of manganese oxalate, manganese monoxide, manganous oxide, manganous phosphate, and manganese hydrogen phosphate.
According to some embodiments of the invention, the iron source is at least one of iron phosphate, iron oxide, ferrous oxalate and iron powder.
According to some embodiments of the invention, the source of phosphorus is at least one of monoammonium phosphate, diammonium phosphate, lithium dihydrogen phosphate, lithium phosphate and phosphoric acid.
According to some embodiments of the invention, the lithium source is at least one of lithium phosphate, lithium dihydrogen phosphate, lithium carbonate, and lithium hydroxide.
According to some embodiments of the invention, step S1 further comprises adding a dopant before the dispersing;
according to some embodiments of the invention, the dopant comprises at least one of a Zn dopant, a Mg dopant, a Ti dopant, an Al dopant, a Cr dopant, a Zr dopant, a Ni dopant, and a Co dopant.
The lithium ion transport path is along [010 ]]Crystal plane orientation; the doping of the metal ions of the doping elements shortens the olivine structure MO 6 (M = Mn, fe, mg) bond length in octahedron, and LiO 6 The Li-O bond in the octahedron can be lengthened, so that the lithium ion diffusion channel is wider and easy to transfer, and the electrochemical performance is improved. Therefore, the lattice distortion generated by the doping of the metal element can reduce the surface energy of the crystal of the positive electrode material, and can inhibit the growth of the crystal to synthesize the nanoscale lithium manganese iron phosphate.
The doping of the metal elements can improve the lithium ion diffusion rate of the lithium ferric manganese phosphate material, so that a lithium ion diffusion channel is wider and easy to move, and the electrochemical performance of the material is improved. Absence of charge compensation defects (e.g. M) in the equivalent of different metal elements 2+ Mg on the site 2+ 、Ni 2+ ) Equivalent doping can create vacancies and the energy of the equivalent substitution is lowest due to the charge compensation mechanism. Further, the larger the difference in charge between the dopant and the host ion, the higher the doping energy of the dopant, which makes the aliovalent doping difficult.
According toSome embodiments of the invention, step S1, the particle size D of the crushed material 50 0.3 to 1.0 μm.
The lithium manganese iron phosphate material can contain a large amount of Li under the particle size + Can be reversibly de-intercalated without causing structural changes of the polymer. Under the particle size, the phenomenon that the Li is increased due to the overlarge particle size of the material is avoided + Diffusion path of (2), reduction of Li + The material rate performance is deteriorated due to the migration rate of (2); meanwhile, the phenomenon that the surface energy is increased and the agglomeration is easy to occur due to the over-small particle size of the material is avoided.
According to some embodiments of the invention, the crushing comprises grinding.
According to some embodiments of the invention, the milling time is 1 to 10 hours.
According to some embodiments of the invention, in step S1, the drying comprises spray drying.
According to some embodiments of the invention, the temperature of the air inlet of the drying process is 180-250 ℃.
According to some embodiments of the invention, the temperature of the outlet of the drying process is between 90 ℃ and 140 ℃.
According to some embodiments of the invention, in step S1, the spray drying comprises constant rate spray drying and reduced rate spray drying.
According to some embodiments of the invention, the feed rate of the spray drying is 5 to 10L/min.
In the constant-speed drying stage, the temperature of the fog drops is kept unchanged, the moisture on the surface is continuously evaporated, the moisture in the liquid drops is transferred to the surface, the drying air continuously transfers heat to the fog drops, and the temperature of carrier gas is reduced; and in the speed reduction drying stage, the surface of the fog drops begins to solidify, the temperature is gradually reduced from outside to inside, and the water content of the granules is gradually reduced. The air inlet/outlet temperature is lower, when the temperature is lower than 180/90 ℃, the time required by the surface solidification of the fog drops is longer, and the particles are easy to agglomerate in the continuous collision process. But the temperature is too high and is higher than 250/140 ℃, so that the chemical property of the precursor is changed, fe and Mn in the material are easily oxidized into high valence, the energy consumption is increased, and the cost is increased.
The invention can realize the rapid transfer of heat and quality by combining the spray drying technology, so that the material is rapidly dried and forms regular nano particles with good uniformity, and the uniform carbon layer can be better coated on the surfaces of the particles by using the MPCVD method.
According to some embodiments of the invention, the temperature of the heat treatment in step S2 is 600 to 800 ℃.
According to some embodiments of the invention, the heat treatment time in step S2 is 10 to 60min.
Microwave Plasma Chemical Vapor Deposition (MPCVD) to synthesize nanoparticles in a very short time can prevent the growth of crystal grains due to conventional long-time high-temperature heat treatment. The small particle size is beneficial to shortening the migration path of lithium ions in the de-intercalation process, and the electrochemical performance of the lithium manganese iron phosphate is effectively improved.
According to some embodiments of the invention, in step S2, the plasma used in the microwave plasma comprises a hydrogen plasma.
According to some embodiments of the invention, the hydrogen plasma has a flow rate of 10 to 100sccm.
In MPCVD, the temperature, time and methane flow rate are used as parameters for adjusting the methane cracking speed, so that the carbon coating effect is influenced, carbon atoms obtained by decomposing methane in unit time are ensured, and a large amount of carbon accumulated carbon particles formed by excessively high methane cracking speed are avoided.
According to some preferred embodiments of the present invention, in step S2, the heat treatment is performed in a Microwave Plasma Chemical Vapor Deposition (MPCVD) reaction tank.
According to some embodiments of the invention, in step S2, the lithium manganese iron phosphate powder material is obtained after the plasma treatment.
According to some embodiments of the invention, in step S3, the carbon-coated carbon source comprises methane.
According to some embodiments of the invention, the flow rate of methane is 10 to 100sccm.
According to some embodiments of the invention, the method of pulverizing comprises jet milling.
According to some embodiments of the invention, the jet mill pulverizes at a classification frequency of 150 to 260Hz.
According to some embodiments of the invention, the jet mill pulverizes at a pressure of 0.3 to 0.6MPa.
According to some embodiments of the invention, the positive electrode material is LiMn x Fe y M z PO 4 X is more than or equal to 0.59 and less than or equal to 0.61,0.36 and less than or equal to 0.38,0.02 and less than or equal to z and less than or equal to 0.04, x + y + z =1, M is at least one of Zn, mg, V, ti, al, cr, zr, ni and Co.
The lithium manganese phosphate is not simple physical mixture of the lithium manganese phosphate and the lithium iron phosphate, and because the iron ions and the manganese ions in the material have similar radiuses, a solid solution is easy to form, so that the atomic-level mixture can be realized. When the Mn content is too high, the alloy is composed of Mn 3+ Elongation of Mn-O bond (with PO) due to Jahn-Teller distortion during charging and discharging 4 3- Edge sharing of tetrahedra, responsible for increasing activation energy for carrier transport), which brings a retardation of the intrinsic kinetics of LMFP with high Mn content. Therefore, in the presence of Mn: fe is about 6: the best performance is exhibited when 4 is used.
According to the second aspect of the embodiment of the invention, the application of the cathode material prepared by the preparation method in the secondary battery is proposed.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is an XRD pattern for example 3 of the present invention;
FIG. 2 is an SEM photograph of example 3 of the present invention;
FIG. 3 is a graph of the electrochemical performance of example 3;
FIG. 4 is a graph of electrochemical performance of comparative example 1;
fig. 5 is a graph of the ac impedance of example 3 and comparative example 1.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention and are not to be construed as limiting the present invention.
Example 1
The embodiment discloses a preparation method of a cathode material, which comprises the following steps of: y: z =0.8:0.18: synthesis of LiMn in a proportion of 0.02 0.8 Fe 0.18 M 0.02 PO 4 The preparation method of the Zn/C/M material comprises the following steps:
s1: weighing 1790g of manganese oxalate, 405g of ferrous oxalate, 1303g of lithium dihydrogen phosphate and 21g of zinc oxide, mixing in 10L of deionized water, fully stirring uniformly, and then sanding by using a sand mill to obtain slurry D 50 Is 0.35 μm;
s2: carrying out centrifugal spray drying on the sanded slurry under the conditions that the inlet temperature is 210 ℃, the outlet temperature is 110 ℃ and the feeding speed is 5L/min to obtain precursor dry powder;
s3: placing the precursor powder obtained by spray drying on a substrate in an MPCVD reaction tank, introducing hydrogen plasma for treatment, wherein the reaction temperature is 600 ℃, the treatment time is 15min, and the hydrogen flow rate is 10sccm to obtain LiMn 0.8 Fe 0.18 Mg 0.02 PO 4 A nanoparticle;
s4: introducing methane gas into LiMn 0.8 Fe 0.18 Mg 0.02 PO 4 Carbon coating is realized on the surface of the nano-particles, the reaction temperature is 700 ℃, the treatment time is 10min, the hydrogen flow rate is 100sccm, the methane flow rate is 10sccm, and LiMn is obtained 0.8 Fe 0.18 Mg 0.02 PO 4 /C；
S5: liMn is milled by adopting an air flow mill 0.8 Fe 0.18 Mg 0.02 PO 4 and/C, crushing, wherein the classification frequency is 220Hz, and the air pressure is 0.5MPa, and obtaining a final finished product.
Example 2
The embodiment discloses a preparation method of a cathode material, which comprises the following steps of: y: z =0.7:0.29: synthesis of LiMn at a ratio of 0.01 0.7 Fe 0.29 M 0.01 PO 4 The preparation method of the Ni-based alloy material comprises the following steps:
s1: weighing 994.5g of manganese hydrogen phosphate, 895g of manganese oxalate, 626.5g of iron phosphate, 523.5g of lithium carbonate and 11g of nickel oxide, mixing in 8L of deionized water, fully stirring uniformly, and sanding by using a sand mill until slurry D 50 0.4 μm;
s2: carrying out centrifugal spray drying on the sanded slurry under the conditions that the inlet temperature is 220 ℃, the outlet temperature is 100 ℃ and the feeding speed is 10L/min to obtain precursor dry powder;
s3: placing the precursor powder obtained by spray drying on a substrate in an MPCVD reaction tank, introducing hydrogen plasma for treatment, wherein the reaction temperature is 700 ℃, the treatment time is 10min, and the hydrogen flow rate is 20sccm to obtain LiMn 0.7 Fe 0.29 Ni 0.01 PO 4 A nanoparticle;
s4: introducing methane gas into LiMn 0.7 Fe 0.29 Ni 0.01 PO 4 Carbon coating is realized on the surface of the nano-particles, the reaction temperature is 650 ℃, the processing time is 20min, the hydrogen flow rate is 90sccm, the methane flow rate is 20sccm, and LiMn is obtained 0.7 Fe 0.29 Ni 0.01 PO 4 /C。
S5: liMn is milled by adopting an air flow mill 0.7 Fe 0.29 Ni 0.01 PO 4 and/C, crushing, wherein the classification frequency is 200Hz, and the air pressure is 0.55MPa, and obtaining a final finished product.
Example 3
The embodiment discloses a preparation method of a cathode material, which comprises the following steps of: y: z =0.6:0.37: synthesis of LiMn at a ratio of 0.03 0.6 Fe 0.37 M 0.03 PO 4 The preparation method of the Mg-Al-Mg-Al alloy comprises the following steps:
s1: 1580g of manganous oxide, 936g of ferric phosphate, 1092g of lithium dihydrogen phosphate, 230g of lithium carbonate and 20g of magnesium oxide are weighed and mixed in 10L of deionized water, and after the materials are fully and uniformly stirred, a sand mill is used for sand grinding until slurry D 50 0.55 μm;
s2: carrying out centrifugal spray drying on the sanded slurry under the conditions that the inlet temperature is 200 ℃, the outlet temperature is 120 ℃ and the feeding speed is 8L/min to obtain precursor dry powder;
s3: placing the precursor powder obtained by spray drying on a substrate in an MPCVD reaction tank, introducing hydrogen plasma for treatment, wherein the reaction temperature is 650 ℃, the treatment time is 10min, and the hydrogen flow rate is 50sccm to obtain LiMn 0.6 Fe 0.37 Mg 0.03 PO 4 A nanoparticle;
s4: introducing methane gas into LiMn 0.6 Fe 0.37 Mg 0.03 PO 4 The carbon coating is realized on the surface of the nano-particles, the reaction temperature is 800 ℃, the processing time is 5min, the hydrogen flow rate is 50sccm, the methane flow rate is 50sccm, and LiMn is obtained 0.6 Fe 0.37 Mg 0.03 PO 4 /C；
S5: liMn is milled by adopting an air flow mill 0.6 Fe 0.37 Mg 0.03 PO 4 and/C, crushing, wherein the grading frequency is 180Hz, and the air pressure is 0.6MPa, and obtaining a final finished product.
The XRD pattern of the product prepared in example 3 is shown in figure 1, and the result shows that the diffraction peak of the sample belongs to an orthorhombic olivine type crystalline structure, and the diffraction peak can be matched with LiMnPO 4 (PFD # 77-0178) Standard card diffraction peaks match, X-ray diffraction peaks are angularly shifted in height, because
Mn of (2) 2+ Radius ratio
Fe (b) of 2+ The lattice spacing of the positive electrode material is reduced; the obtained peak intensity is equivalent, the crystallinity is good, and the pure lithium iron manganese phosphate is synthesized, carbon exists in an amorphous form, and cannot be detected by XRD, so that the crystal structure of the material is not influenced by the existence of the carbon.
The SEM image of the product prepared in example 3 is shown in fig. 2. The results show that carbon-coated lithium manganese iron phosphate has a uniform particle size distribution, which indicates that MPCVD is a very effective way to control particle size because MPCVD can synthesize nanoparticles in a very short time and can avoid grain growth caused by conventional long-time high-temperature heat treatment. The prepared small particle size is beneficial to shortening the migration path of lithium ions in the de-intercalation process, and can effectively improve the electrochemical performance of the lithium manganese iron phosphate.
Example 4
The embodiment discloses a preparation method of a cathode material, which comprises the following steps of: y: z =0.5:0.48: synthesis of LiMn in a proportion of 0.02 0.5 Fe 0.48 M 0.02 PO 4 The preparation method comprises the following steps:
s1: weighing 790g of manganese sesquioxide, 768g of ferric oxide, 1040g of lithium dihydrogen phosphate and 16g of titanium dioxide, mixing the materials in 8L of deionized water, fully stirring the materials uniformly, and sanding the mixture by using a sand mill until slurry D 50 0.4 μm;
s2: spray drying the sanded slurry under the conditions that the inlet temperature is 210 ℃, the outlet temperature is 110 ℃ and the feeding speed is 6L/min to obtain precursor dry powder;
s3: placing the precursor powder obtained by spray drying on a substrate in an MPCVD reaction tank, introducing hydrogen plasma for treatment, wherein the reaction temperature is 700 ℃, the treatment time is 10min, and the hydrogen flow rate is 20sccm to obtain LiMn 0.5 Fe 0.48 M 0.02 PO 4 ；
S4: introducing methane gas into LiMn 0.6 Fe 0.37 Mg 0.03 PO 4 Carbon coating is realized on the surface of the nano-particles, the reaction temperature is 800 ℃, the treatment time is 5min, the hydrogen flow rate is 50sccm, the methane flow rate is 50sccm, and LiMn is obtained 0.6 Fe 0.37 Mg 0.03 PO 4 /C；
S5: introducing methane gas to realize carbon coating on the surface of the LMFP nano-particles, wherein the reaction temperature is 800 ℃, the treatment time is 25min, the hydrogen flow rate is 100sccm, and the methane flow rate is 10sccm to obtain LiMn 0.5 Fe 0.48 M 0.02 PO 4 /C。
Example 5
The embodiment discloses a positive electrodeThe material was prepared as described in example 3, except that no dopant containing the doping element was added, and the ratio of x: y: z =0.6:0.4:0 ratio Synthesis of LiMn 0.6 Fe 0.4 PO 4 and/C nano-particles. The rest conditions are the same.
Example 6
The embodiment discloses a preparation method of a cathode material, which is different from the embodiment 3 in that precursor powder obtained by spray drying is placed on a substrate in an MPCVD reaction tank, hydrogen plasma is introduced for treatment, the reaction temperature is 700 ℃, the treatment time is 20min, and the hydrogen flow rate is 80sccm.
Example 7
This example discloses a method for preparing a positive electrode material, which is different from example 3 in that Ni is added as a dopant containing a doping element, and the remaining conditions are the same.
Example 8
This example discloses a method for producing a positive electrode material, and differs from example 3 in that sanding was performed to slurry D using a sand mill in step S1 50 And was 0.8 μm.
Example 9
This example discloses a method for preparing a positive electrode material, and differs from example 3 in that the reaction temperature is 750 ℃ in step S3.
Example 10
This example discloses a method for preparing a positive electrode material, and differs from example 3 in that in step S3, the treatment time is 25min.
Example 11
This example discloses a method for preparing a positive electrode material, which is different from example 3 in that the flow rate of hydrogen is 100sccm in step S3.
Example 12
This example discloses a method for preparing a positive electrode material, and differs from example 3 in that the reaction temperature is 600 ℃ in step S4.
Example 13
This example discloses a method for producing a positive electrode material, and differs from example 3 in that in step S3, the treatment time is 25min.
Example 14
This example discloses a method for preparing a positive electrode material, and is different from example 3 in that the flow rate of methane is 100sccm in step S3.
Comparative example 1
This comparative example discloses a method for preparing a positive electrode material, which is different from example 3 in that a soluble organic carbon source (glucose) was used as a carbon source, mixed in a slurry, subjected to sand milling, spray drying, and then synthesized into LiMn in a tube furnace under a nitrogen atmosphere 0.6 Fe 0.37 M 0.03 PO 4 and/C nano-particles.
Plots of the pull-out performance of the products prepared in example 3 and comparative example 1 are shown in figures 3 and 4. FIG. 3 is a charge-discharge curve at 0.1C for the sample prepared in example 3, with a 0.1C specific discharge capacity of 155mAh/g; FIG. 4 is a charge-discharge curve at 0.1C for the sample prepared in comparative example 1, with a 0.1C specific discharge capacity of 142mAh/g; the result shows that the lithium manganese iron phosphate material coated with carbon by the MPCVD method has better performance.
The pull-out performance plots for the products prepared in example 3 and comparative example 1 are shown in figures 4 and 5. FIG. 5 is an AC impedance spectrum of example 3 and comparative example 1, the impedance spectrum consisting of a high frequency region and a low frequency region, the semicircular diameter of the high frequency region representing the electrochemical transfer impedance R ct The straight line in the low frequency region represents Li + Has the maximum R in comparative example 1 ct The values show that the sample is greatly hindered and has low electronic conductivity, so that the sample has large polarization and low specific capacity in the charging and discharging processes.
Test example 1
This test example tested the charge and discharge test results of the positive electrode materials of examples 1 to 14 and comparative example 1, and the test results are shown in table 1, wherein examples 1 to 14 and comparative example 1 employ LiPF of equal volume 6 And diethyl carbonate (DEC) electrolyte, liPF 6 The concentration of (2) is 1M, a metal lithium sheet is used as a negative electrode to prepare a button type half cell, and a LAND cell program control tester (LAND CT 2001A) is used for detecting the multiplying power performance of the cell.
TABLE 1 Performance test results
In the invention, the carbon layers deposited by the microwave plasma chemical vapor deposition Method (MPCVD) in the embodiments 1 to 14 not only protect the carbon-coated positive electrode sheet from being corroded by the electrolyte, but also improve the electronic/ionic conductivity and the electrochemical performance due to the high graphitization degree of the positive electrode material.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.
Claims (10)
1. The preparation method of the cathode material is characterized by comprising the following steps of:
s1, mixing and dispersing a manganese source, an iron source, a lithium source and a phosphorus source, crushing and drying;
s2, carrying out heat treatment on the powder obtained after drying in the step S1, wherein the heat treatment is carried out in a microwave plasma environment;
obtaining a lithium manganese iron phosphate material after the heat treatment;
s3, carrying out carbon coating on the powder obtained in the step S2 and then crushing the powder; the carbon coating method is a microwave plasma chemical vapor deposition method.
2. The method for preparing the cathode material according to claim 1, wherein in step S1, the step of adding a dopant before the dispersing; preferably, the dopant includes at least one of a Zn dopant, a Mg dopant, a Ti dopant, an Al dopant, a Cr dopant, a Zr dopant, a Ni dopant, and a Co dopant.
3. The method for producing a positive electrode material according to claim 1, wherein in step S1, D in the crushed material 50 0.3-1.0 μm.
4. The method for producing a positive electrode material according to claim 1, wherein in step S1, the drying includes spray drying; preferably, the temperature of the air inlet in the spray drying process is 180-250 ℃, and preferably, the temperature of the air outlet in the spray drying process is 90-140 ℃.
5. The method for producing a positive electrode material according to claim 1, wherein the temperature of the heat treatment in step S2 is 600 to 800 ℃.
6. The method for preparing a positive electrode material according to claim 1, wherein in step S2, the plasma used in the microwave plasma comprises a hydrogen plasma; preferably, the flow rate of the hydrogen plasma is 10 to 100sccm.
7. The method for producing a positive electrode material according to claim 1, wherein the carbon-coated carbon source includes methane in step S3.
8. The method for producing a positive electrode material according to claim 7, wherein the flow rate of methane is 10 to 100sccm.
9. The method for producing a positive electrode material according to claim 1, wherein the positive electrode material is LiMn x Fe y M z PO 4 /C，0<x≤1，0<y is not less than 0.95,0 is not less than 0.05, x + y + z =1, M is at least one of Zn, mg, V, ti, al, cr, zr, ni and Co.
10. Use of the positive electrode material prepared by the preparation method according to any one of claims 1 to 9 in the preparation of a secondary battery.
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| CN202210931373.5A CN115394976A (en) | 2022-08-04 | 2022-08-04 | Preparation method and application of positive electrode material |
| PCT/CN2022/118781 WO2024026984A1 (en) | 2022-08-04 | 2022-09-14 | Preparation method for and use of positive electrode material |
| FR2308339A FR3138736A1 (en) | 2022-08-04 | 2023-08-01 | PREPARATION METHOD AND USE OF CATHODE MATERIAL |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11717886B2 (en) | 2019-11-18 | 2023-08-08 | 6K Inc. | Unique feedstocks for spherical powders and methods of manufacturing |
| CN117023548A (en) * | 2023-10-09 | 2023-11-10 | 天津斯科兰德科技有限公司 | Lithium iron manganese phosphate material and preparation method thereof |
| US11839919B2 (en) | 2015-12-16 | 2023-12-12 | 6K Inc. | Spheroidal dehydrogenated metals and metal alloy particles |
| US11855278B2 (en) | 2020-06-25 | 2023-12-26 | 6K, Inc. | Microcomposite alloy structure |
| US11919071B2 (en) | 2020-10-30 | 2024-03-05 | 6K Inc. | Systems and methods for synthesis of spheroidized metal powders |
| US11963287B2 (en) | 2020-09-24 | 2024-04-16 | 6K Inc. | Systems, devices, and methods for starting plasma |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104716320B (en) * | 2015-03-10 | 2017-06-16 | 中国科学院过程工程研究所 | A kind of LiFePO4 of composite cladding, its preparation method and lithium ion battery |
| US20170373344A1 (en) * | 2016-06-23 | 2017-12-28 | Amastan Technologies Llc | Lithium ion battery materials |
| JP2022514676A (en) * | 2018-12-20 | 2022-02-14 | シックスケー インコーポレイテッド | Plasma treatment of lithium transition metal oxides for lithium ion batteries |
| CN114744315A (en) * | 2022-03-09 | 2022-07-12 | 昆明理工大学 | Direct regeneration method of waste lithium iron phosphate anode material |
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2022
- 2022-08-04 CN CN202210931373.5A patent/CN115394976A/en active Pending
- 2022-09-14 WO PCT/CN2022/118781 patent/WO2024026984A1/en unknown
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11839919B2 (en) | 2015-12-16 | 2023-12-12 | 6K Inc. | Spheroidal dehydrogenated metals and metal alloy particles |
| US11717886B2 (en) | 2019-11-18 | 2023-08-08 | 6K Inc. | Unique feedstocks for spherical powders and methods of manufacturing |
| US11855278B2 (en) | 2020-06-25 | 2023-12-26 | 6K, Inc. | Microcomposite alloy structure |
| US11963287B2 (en) | 2020-09-24 | 2024-04-16 | 6K Inc. | Systems, devices, and methods for starting plasma |
| US11919071B2 (en) | 2020-10-30 | 2024-03-05 | 6K Inc. | Systems and methods for synthesis of spheroidized metal powders |
| CN117023548A (en) * | 2023-10-09 | 2023-11-10 | 天津斯科兰德科技有限公司 | Lithium iron manganese phosphate material and preparation method thereof |
| CN117023548B (en) * | 2023-10-09 | 2024-03-12 | 天津容百斯科兰德科技有限公司 | Lithium iron manganese phosphate material and preparation method thereof |
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| WO2024026984A1 (en) | 2024-02-08 |
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