Method for preparing cathode material precursor, cathode material precursor, method for preparing cathode material, cathode material and battery

Abstract

The present application relates to the field of battery, specifically relates to a kind of preparation of positive electrode material precursor method, positive electrode material precursor prepared by the method, the method for preparing positive electrode material, positive electrode material prepared by the method and the battery comprising the positive electrode material.The preparation of positive electrode material precursor described method includes the following steps: (1) element M source, solvent and optional first sodium source are mixed, sand grinding;(2) the slurry obtained in step (1) is spray dried;Wherein, the molar ratio of the first sodium source calculated in terms of sodium and the element M source calculated in terms of element M is (0-0.9):1.The positive electrode material precursor prepared by the method of the present application has low hollow rate and high bulk density.The positive electrode material prepared by the method of the present application has excellent electrochemical performance, and the battery comprising the positive electrode material of the present application has better capacity and cycle life.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of batteries, in particular to a method for preparing a positive electrode material precursor, a positive electrode material precursor prepared by the method, a method for preparing a positive electrode material, a positive electrode material prepared by the method, and a battery comprising the positive electrode material. BACKGROUND

[0002] With the development of mobile devices and the continuous growth of demand, the demand for secondary batteries as energy sources also grows. Sodium-ion batteries are attracting more and more attention as a potential secondary battery. The positive electrode material precursor prepared using the "sand grinding + spraying" method has a high hollow rate and a low bulk density, resulting in poor electrochemical performance of the sintered positive electrode material, including poor capacity and cycle life of the battery comprising the positive electrode material. SUMMARY

[0003] The present application aims to overcome the problem of poor capacity and cycle life of the battery caused by the preparation method in the prior art, and provides a method for preparing a positive electrode material precursor, a positive electrode material precursor prepared by the method, a method for preparing a positive electrode material, a positive electrode material prepared by the method, and a battery comprising the positive electrode material. The positive electrode material precursor prepared by the method of the present application has a low hollow rate and a high bulk density. The positive electrode material prepared by the method of the present application has excellent electrochemical performance. The battery comprising the positive electrode material of the present application has a better capacity and cycle life.

[0004] The first aspect of the present application provides a method for preparing a positive electrode material precursor, the method comprising the following steps: (1) mixing an element M source, a solvent and an optional first sodium source, and sand grinding; (2) spray drying the slurry obtained in step (1); wherein the molar ratio of the first sodium source calculated based on sodium to the element M source calculated based on element M is (0-0.9): 1.

[0005] In an example, the molar ratio of the first sodium source calculated based on sodium to the element M source calculated based on element M is (0-0.5): 1.

[0006] In an example, the molar ratio of the first sodium source calculated based on sodium to the element M source calculated based on element M is (0.05-0.2): 1.

[0007] In an example, the ratio of the total mass of the element M source and the first sodium source to the mass of the solvent is 1:(0.5-9.5).

[0008] In an example, the ratio of the total mass of the element M source and the first sodium source to the mass of the solvent is (1.5-4): 1.

[0009] In an example, the solvent comprises at least one of deionized water, absolute ethanol, and isopropyl alcohol.

[0010] In an example, the solvent comprises deionized water.

[0011] In an example, the element M source comprises at least one of a copper source, an iron source, a manganese source, a nickel source, a cobalt source, a titanium source, a magnesium source, an aluminum source, a vanadium source, and a vanadium source.

[0012] In an example, the element M source comprises at least one of an oxide of copper, an oxide of iron, an oxide of manganese, an oxide of nickel, an oxide of cobalt, an oxide of titanium, an oxide of magnesium, an oxide of aluminum, and an oxide of vanadium.

[0013] In an example, the first sodium source comprises at least one of sodium carbonate, sodium dihydrogen phosphate, sodium hydroxide, sodium acetate, and sodium oxalate.

[0014] In an example, the first sodium source comprises at least one of sodium carbonate, sodium hydroxide, sodium acetate, and sodium oxalate.

[0015] In an example, in step (1), further comprising adding an element R source; the R source comprises at least one of a phosphorus source, a sulfur source, a silicon source, an arsenic source, a molybdenum source, and a tungsten source.

[0016] In an example, the molar ratio of the first sodium source in terms of sodium, the element M source in terms of element M, and the element R source in terms of element R is (0-0.9):1:(1-3).

[0017] In an example, the sand-milled material has a median particle size Dv50 of 100 nm-800 nm.

[0018] In an example, the spray-drying condition is: an inlet air temperature of 200°C-280°C, an atomizer rotation speed of 25,000 rpm-35,000 rpm, a feed rate of 50 ml / min-130 ml / min, and an outlet air temperature of 95°C-120°C.

[0019] In an example, the spray-dried positive electrode material precursor has a median particle size Dv50 of 5 μm-25 μm.

[0020] In an example, the spray-dried positive electrode material precursor has a median particle size Dv50 of 10 μm-15 μm.

[0021] In an example, the spray-dried positive electrode material precursor has a solvent content of ≤5%.

[0022] In an example, the spray-dried positive electrode material precursor has a solvent content of ≤3%.

[0023] In an example, the bulk density of the spray-dried positive electrode material precursor is ≥ 0.6 g / cm 3 .

[0024] In an example, the bulk density of the spray-dried positive electrode material precursor is ≥ 0.8 g / cm 3 .

[0025] The second aspect of the present application provides a positive electrode material precursor, which is prepared by the method of the first aspect of the present application.

[0026] The third aspect of the present application provides a method for preparing a positive electrode material, which comprises the following steps: mixing a positive electrode material precursor and a second sodium source, and sintering; the positive electrode material precursor comprises the positive electrode material precursor of the second aspect of the present application.

[0027] In an example, the mass ratio of the second sodium source and the element M source is (0.15-2):1.

[0028] In an example, the second sodium source comprises at least one of sodium carbonate, sodium dihydrogen phosphate, sodium hydroxide, sodium acetate and sodium oxalate.

[0029] The fourth aspect of the present application provides a positive electrode material, which is prepared by the method of the third aspect of the present application.

[0030] In an example, the positive electrode material comprises a substance with a chemical formula of Na x M 1 O2 and / or a substance with a chemical formula of Na y M 2 z (RO4)3; wherein M 1 is at least one selected from Cu, Fe, Mn, Ni, Co and V, 0.6≤x≤1; M 2 is at least one selected from Cu, Fe, Mn, Ni, Co and V, R is at least one selected from S, P, Si, As, Mo and W, 1≤y≤3, 1≤z≤2.

[0031] The fifth aspect of the present application provides a battery, which comprises the positive electrode material of the fourth aspect of the present application.

[0032] Compared with the prior art, the present application has at least the following advantages:

[0033] (1) The positive electrode material precursor prepared by the method of the present application has high bulk density and sphericity, and the bulk density is controllable;

[0034] (2) The positive electrode material prepared by the method has stable structure and excellent electrochemical performance;

[0035] (3) The battery comprising the positive electrode material has excellent capacity and cycle life.

[0036] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not to be understood as being crucial in light of the functions to be fulfilled by the dimensions. The disclosed ranges are to be understood to include values near the recited ones. This means that if, for example, a numeric range from 100 to 200 is disclosed, a range from 90 to 210 is to be understood as also disclosed. For numeric ranges, the endpoints between the individual ranges, the endpoints between the individual ranges and the individual points, and the individual points can be combined with each other to give one or more new numeric ranges, which are to be understood as being specifically disclosed herein. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 The electron microscope images of the precursors prepared from Example I1, Example I4c and Comparative Example D1 are shown. DETAILED DESCRIPTION

[0038] The specific embodiments of the present application are described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and explanatory and are not to be construed as limiting the present application.

[0039] In the related art, several raw materials that need to be mixed and sintered are mixed in advance through a wet sanding process, and then are subjected to spray drying and sintering, so that good mixing effect can be achieved. However, the positive electrode material precursor prepared by this process has poor balling effect, high hollow rate and low bulk density, which affects the production capacity, and leads to poor structure stability and poor electrochemical performance of the positive electrode material, thereby directly affecting the capacity and cycle life of the battery. The inventors of the present application found through long-term research that the reason for the above problems may be that the raw material for preparing the positive electrode material precursor contains sodium salt, which crystallizes and precipitates during spray drying, which destroys the balling effect of the material after spray drying, and the volume shrinks to form a large number of voids, thereby increasing the hollow rate and reducing the bulk density, thereby seriously affecting the production capacity; and directly reduces the stability of the material after spray drying, which leads to easy breakage, affects the stability of the element ratio in the dried material, and thereby directly affects the capacity and cycle life of the battery. The inventors of the present application further found that by controlling the content of sodium salt during spray drying, the above problems can be effectively improved.

[0040] The first aspect of the present application provides a method for preparing a positive electrode material precursor, which can comprise the following steps:

[0041] (1) mixing an element M source, a solvent and an optional first sodium source, and sanding;

[0042] (2) spray drying the slurry obtained in step (1);

[0043] The molar ratio of the first sodium source calculated as sodium to the element M source calculated as element M can be (0-0.9):1, such as 0:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1 or 0.9:1.

[0044] In one example, the molar ratio of the first sodium source calculated as sodium to the element M source calculated as element M is (0-0.5):1.

[0045] In one example, the molar ratio of the first sodium source calculated as sodium to the element M source calculated as element M is (0.05-0.2):1.

[0046] The inventors of the present application found that when the molar ratio of the first sodium source calculated as sodium to the element M source calculated as element M is within a specific range, the crystallization of the material during the spray drying process can be effectively reduced, thereby improving the balling effect of the positive material precursor after spray drying, reducing the hollow rate and improving the bulk density.

[0047] In the present application, the ratio of the total mass of the element M source and the first sodium source to the mass of the solvent can be 1:(0.5-9.5), such as 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:9.5.

[0048] In one example, the ratio of the total mass of the element M source and the first sodium source to the mass of the solvent is 1:(1.5-4).

[0049] The inventors of the present application found that when the ratio of the total mass of the element M source and the first sodium source to the mass of the solvent is within a specific range, the sanding efficiency can be improved.

[0050] In the present application, the solvent can include at least one of deionized water, anhydrous ethanol and isopropyl alcohol.

[0051] In one example, the solvent includes deionized water.

[0052] The inventors of the present application found that when the solvent includes deionized water, the surface tension of the slurry can be improved, which is beneficial to the formation of particles with good balling effect during the spray drying process, thereby improving the capacity and cycle life of the battery.

[0053] In the present application, the element M source can include at least one of a copper source, an iron source, a manganese source, a nickel source, a cobalt source, a titanium source, a magnesium source, an aluminum source and a vanadium source.

[0054] In the present application, the source of element M can comprise at least one of an oxide, a carbonate, a nitrate, an acetate, an oxalate and a hydroxide of element M.

[0055] In one example, the source of element M comprises at least one of an oxide of copper, an oxide of iron, an oxide of manganese, an oxide of nickel, an oxide of cobalt, an oxide of titanium, an oxide of magnesium, an oxide of aluminium and an oxide of vanadium.

[0056] In the present application, the first source of sodium can comprise a sodium salt.

[0057] In one example, the first source of sodium comprises at least one of sodium carbonate, sodium dihydrogen phosphate, sodium hydroxide, sodium acetate and sodium oxalate.

[0058] In one example, the first source of sodium comprises at least one of sodium carbonate, sodium hydroxide, sodium acetate and sodium oxalate.

[0059] In the present application, in step (1), a source of element R can also be added, mixed with the source of element M, the solvent and the optional first source of sodium. The source of R can comprise at least one of a source of phosphorus, a source of sulphur, a source of silicon, a source of arsenic, a source of molybdenum and a source of tungsten. The source of phosphorus can comprise a phosphate salt.

[0060] In the present application, in step (1), the molar ratio of the first source of sodium, calculated as sodium, the source of element M, calculated as element M, and the source of element R, calculated as element R, can be (0-0.9):1:(1-3), for example 0:1:1, 0:1:1.5, 0:1:3, 0.1:1:1, 0.1:1:1.5, 0.1:1:3, 0.5:1:1, 0.5:1:1.5, 0.5:1:3, 0.9:1:1, 0.9:1:1.5 or 0.9:1:3.

[0061] In the present application, the median particle size Dv50 of the milled material can be in the range of 100 nm to 800 nm, for example 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm or 800 nm.

[0062] In the present application, the median particle size Dv50 of the milled material can be tested by conventional methods in the art, for example by laser particle sizer test method.

[0063] In the present application, the spray drying conditions can be: the inlet air temperature can be 200-280°C (e.g. 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C or 280°C), the atomizer rotation speed can be 25000-35000rpm (e.g. 25000rpm, 30000rpm or 35000rpm), the feed rate can be 50-130ml / min (e.g. 50ml / min, 60ml / min, 70ml / min, 80ml / min, 90ml / min, 100ml / min, 110ml / min, 120ml / min or 130ml / min), and the outlet air temperature can be 95-120°C (e.g. 95°C, 100°C, 105°C, 110°C, 115°C or 120°C).

[0064] In the present application, the median particle size Dv50 of the spray-dried positive electrode material precursor can be 5-25μm, e.g. 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm or 25μm.

[0065] In one example, the median particle size Dv50 of the spray-dried positive electrode material precursor is 10-15μm.

[0066] In the present application, the median particle size Dv50 of the spray-dried positive electrode material precursor can be tested by conventional methods in the art, e.g. laser particle size analyzer method.

[0067] In the present application, the solvent content of the spray-dried positive electrode material precursor is ≤5%, e.g. 0, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4% or 5%.

[0068] In one example, the solvent content of the spray-dried positive electrode material precursor is ≤3%.

[0069] In the present application, the solvent content of the spray-dried positive electrode material precursor can be tested by conventional methods in the art, e.g. by moisture meter.

[0070] In the present application, the bulk density of the spray-dried positive electrode material precursor is ≥0.6g / cm 3 , e.g. 0.6g / cm 3 , 0.7g / cm 3 , 0.8g / cm3 0.9 g / cm 3 1 g / cm 3 1.1 g / cm 3 or 1.2 g / cm 3 .

[0071] In an example, the bulk density of the spray-dried positive electrode material precursor is ≥ 0.8 g / cm 3 .

[0072] In the present application, the bulk density of the spray-dried positive electrode material precursor can be tested by the conventional method in the art, for example, the Scott volumeter method in GB / T 1479.2-2011.

[0073] The method for preparing a positive electrode material precursor of the present application can effectively control the sphericity of the positive electrode material precursor obtained after spray-drying by controlling the amount of the first sodium source added, so as to balance the element proportion; and can also control the hollow rate of the positive electrode material precursor, so as to control the bulk density.

[0074] The second aspect of the present application provides a positive electrode material precursor, which is prepared by the method of the first aspect of the present application.

[0075] In the present application, the median particle size Dv50 of the positive electrode material precursor can be 5 μm-25 μm, for example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 21 μm, 22 μm, 23 μm, 24 μm or 25 μm.

[0076] In an example, the median particle size Dv50 of the positive electrode material precursor is 10 μm-15 μm.

[0077] In the present application, the bulk density of the positive electrode material precursor is ≥ 0.6 g / cm 3 , for example, 0.6 g / cm 3 , 0.7 g / cm 3 , 0.8 g / cm 3 , 0.9 g / cm 3 , 1 g / cm 3 , 1.1 g / cm 3 or 1.2 g / cm 3 .

[0078] In an example, the bulk density of the positive electrode material precursor is ≥ 0.8 g / cm 3 .

[0079] The positive electrode material precursor has good balling effect, low hollow rate and high loose bulk density, and can effectively improve the production capacity.

[0080] The third aspect of the present application provides a method for preparing a positive electrode material, which can include the following steps: mixing a positive electrode material precursor and a second sodium source, and sintering.

[0081] In an example, the positive electrode material precursor includes the positive electrode material precursor prepared by the method of the first aspect of the present application and / or the positive electrode material precursor of the second aspect of the present application.

[0082] In an example, the positive electrode material precursor is the positive electrode material precursor prepared by the method of the first aspect of the present application and / or the positive electrode material precursor of the second aspect of the present application.

[0083] In the present application, the molar ratio of the second sodium source calculated based on sodium to the element M source calculated based on element M can be (0.15-2):1, for example, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1.

[0084] In an example, the molar ratio of the second sodium source calculated based on sodium to the element M source calculated based on element M is (0.55-1.05):1.

[0085] In an example, the molar ratio of the second sodium source calculated based on sodium to the element M source calculated based on element M is (0.85-1):1.

[0086] The inventors of the present application found that when the molar ratio of the second sodium source calculated based on sodium to the element M source calculated based on element M is within a certain range, the distribution of sodium elements on the surface of the positive electrode material is facilitated, and the electrochemical performance and structural stability of the prepared positive electrode material can be improved.

[0087] In the present application, the second sodium source can include a sodium salt. The second sodium source can include at least one of sodium carbonate, sodium dihydrogen phosphate, sodium hydroxide, sodium acetate and sodium oxalate.

[0088] In an example, the second sodium source includes at least one of sodium carbonate, sodium hydroxide, sodium acetate and sodium oxalate.

[0089] In the present application, the sintering can comprise a first sintering stage and a second sintering stage. The temperature of the first sintering stage can be 300-500°C, such as 300°C, 350°C, 400°C, 450°C or 500°C. The time of the first sintering stage can be 1-5h, such as 1h, 2h, 3h, 4h or 5h. The temperature of the second sintering stage can be 800-1050°C, such as 800°C, 850°C, 900°C, 950°C, 1000°C or 1050°C. The time of the second sintering stage can be 10-20h, such as 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h or 20h. The temperature ramping rate between the first sintering stage and the second sintering stage can be 2-5°C / min, such as 2°C / min, 3°C / min, 4°C / min or 5°C / min. The atmosphere of the sintering can be at least one of air, oxygen and inert gas. The inert gas comprises at least one of nitrogen and argon.

[0090] In the present application, the sintering can further comprise a crushing after the sintering.

[0091] The fourth aspect of the present application provides a positive electrode material, which is prepared by the method of the third aspect of the present application.

[0092] In the present application, the median particle size Dv50 of the positive electrode material can be 1-10μm, such as 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0093] In an example, the median particle size Dv50 of the positive electrode material is 3-7μm.

[0094] In the present application, the positive electrode material can comprise a substance with a chemical formula of Na x M 1 O2and / or a substance with a chemical formula of Na y M 2 z (RO4)3.

[0095] wherein M 1 may be selected from at least one of Cu, Fe, Mn, Ni, Co and V, 0.6≤x≤1, such as x=0.6, 0.67, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95 or 1.

[0096] In an example, 0.8≤x≤1.

[0097] In an example, the positive electrode material comprises a substance with a chemical formula of NaCu 0.1 Fe0.4 Mn 0.3 Ni 0.2 O2.

[0098] In one example, the cathode material comprises a chemical formula of NaFe 0.4 Mn 0.3 Ni 0.3 O2.

[0099] wherein M 2 may be selected from at least one of Cu, Fe, Mn, Ni, Co and V, R can be selected from at least one of S, P, Si, As, Mo and W, 1≤y≤3, 1≤z≤2.

[0100] In one example, the cathode material comprises a chemical formula of Na3V2(PO4)3.

[0101] In one example, the cathode material comprises a chemical formula of NaFe(PO4)3.

[0102] The present application also provides a cathode sheet, which comprises the cathode material prepared by the method of the third aspect of the present application and / or the cathode material of the fourth aspect of the present application.

[0103] In one example, the cathode sheet comprises a cathode current collector and a cathode coating layer coated on at least one side surface of the cathode current collector, and the cathode coating layer can comprise the cathode material.

[0104] The cathode coating layer can further comprise a cathode conductive agent and a cathode binder. The cathode conductive agent can comprise a conductive agent conventionally used in the art, for example comprising conductive carbon black. The cathode binder can comprise a binder conventionally used in the art, for example comprising polyvinylidene fluoride.

[0105] The content of the cathode material can be 80-99 wt% (for example 80, 85, 90, 95 or 99 wt%), the content of the cathode binder can be 0.5-10 wt% (for example 10, 7.5, 5, 2.5 or 0.5 wt%), and the content of the cathode conductive agent can be 0.5-10 wt% (for example 10, 7.5, 5, 2.5 or 0.5 wt%) based on the total weight of the cathode coating layer.

[0106] The fifth aspect of the present application provides a battery, which comprises the cathode material prepared by the method of the third aspect of the present application and / or the cathode material of the fourth aspect of the present application.

[0107] In the present application, the battery can further comprise a negative electrode sheet, a separator and an electrolyte.

[0108] In an example, the negative electrode sheet comprises a negative electrode current collector and a negative electrode coating layer coated on at least one side surface of the negative electrode current collector, and the negative electrode coating layer can comprise a negative electrode material.

[0109] The negative electrode material can comprise a negative electrode material conventionally used in the art, for example comprising at least one of graphite, soft carbon, hard carbon and silicon material.

[0110] The negative electrode coating layer can further comprise a negative electrode conductive agent and a negative electrode binder. The negative electrode conductive agent can comprise a conductive agent conventionally used in the art, for example comprising conductive carbon black. The negative electrode binder can comprise a binder conventionally used in the art, for example comprising sodium carboxymethyl cellulose.

[0111] In the present application, the content of the negative electrode material can be 80-99 wt% (for example 80, 85, 90, 95 or 99 wt%) based on the total weight of the negative electrode coating layer, the content of the negative electrode binder can be 0.5-10 wt% (for example 10, 7.5, 5, 2.5 or 0.5 wt%), and the content of the negative electrode conductive agent can be 0.5-10 wt% (for example 10, 7.5, 5, 2.5 or 0.5 wt%).

[0112] In the present application, the separator can comprise a separator conventionally used in the art, for example a polyethylene film.

[0113] In the present application, the electrolyte can comprise an electrolyte conventionally used in the art.

[0114] The preparation method of the battery can be carried out in the manner in the art, and all can achieve the effect of the present application.

[0115] It should be noted that the "first", "second" and the like numerical representation in the present application is only used to distinguish different substances or usage manners, and does not represent the difference in order.

[0116] The present application will be described in detail below through examples. The examples described in the present application are only a part of the examples of the present application, but not all the examples. Based on the examples in the present application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0117] In the following examples, the materials used are commercially available analytical pure unless otherwise specified.

[0118] The following Group I examples are used to illustrate the positive electrode material of the present application.

[0119] Example I1

[0120] The positive electrode material is prepared according to the following steps:

[0121] (1) Iron oxide calculated as Fe, nickel oxide calculated as Ni, manganese oxide calculated as Mn and sodium carbonate calculated as Na were weighed and mixed in a molar ratio of 0.4:0.3:0.3:0.1, and the obtained mixture was mixed with deionized water in a mass ratio of 1:2, and was added into a sand mill, until the median particle size Dv50 of the sand-milled material was 300 nm;

[0122] (2) The slurry prepared in step (1) was pumped into a spray dryer using a peristaltic pump, and the inlet air temperature was set to 250°C, the atomizer speed was set to 30000 rpm, the feeding speed was set to 80 ml / min, and the outlet air temperature was set to 100°C, to obtain a positive electrode material precursor;

[0123] (3) The positive electrode material precursor (calculated as element M) prepared in step (2) and anhydrous sodium carbonate (calculated as Na) were mixed in a molar ratio of 1:0.95, and were sintered using a box furnace, with a sintering procedure of 450°C for 2 h and 950°C for 12 h, in an air atmosphere, at a heating rate of 3°C / min, and were broken after cooling to room temperature to obtain a positive electrode material, with a Dv50 of 5 pm.

[0124] Example I2

[0125] A positive electrode material was prepared according to the following steps:

[0126] (1) Iron oxide calculated as Fe, nickel oxide calculated as Ni, manganese oxide calculated as Mn and sodium hydroxide calculated as Na were weighed and mixed in a molar ratio of 0.4:0.3:0.3:0.05, and the obtained mixture was mixed with deionized water in a mass ratio of 1:4, and was added into a sand mill, until the median particle size Dv50 of the sand-milled material was 350 nm;

[0127] (2) The slurry prepared in step (1) was pumped into a spray dryer using a peristaltic pump, and the inlet air temperature was set to 200°C, the atomizer speed was set to 25000 rpm, the feeding speed was set to 50 ml / min, and the outlet air temperature was set to 95°C, to obtain a positive electrode material precursor;

[0128] (3) The positive electrode material precursor (calculated as element M) prepared in step (2) and sodium hydroxide (calculated as Na) were mixed in a molar ratio of 1:1, and were sintered using a box furnace, with a sintering procedure of 300°C for 5 h and 800°C for 20 h, in an air atmosphere, at a heating rate of 4°C / min, and were broken after cooling to room temperature to obtain a positive electrode material, with a Dv50 of 3 pm.

[0129] Example I3

[0130] A positive electrode material was prepared according to the following steps:

[0131] (1) Iron oxide calculated as Fe, nickel oxide calculated as Ni, manganese oxide calculated as Mn and sodium acetate calculated as Na were weighed and mixed in a molar ratio of 0.4:0.3:0.3:0.2, and the obtained mixture was mixed with deionized water in a mass ratio of 1:1.5, and then was added into a sand mill, until the median particle size Dv50 of the material after sand milling was 600 nm;

[0132] (2) The slurry prepared in step (1) was pumped into a spray dryer using a peristaltic pump, and the inlet air temperature was set to 280°C, the atomizer speed was set to 35000 rpm, the feeding speed was set to 130 ml / min, and the outlet air temperature was set to 120°C, to obtain a positive electrode material precursor;

[0133] (3) The positive electrode material precursor prepared in step (2) (calculated as element M) and sodium acetate (calculated as Na) were mixed in a molar ratio of 1:0.85, and were sintered using a box furnace, with a sintering program of 500°C for 1 h, 1050°C for 10 h, in an air atmosphere, at a heating rate of 5°C / min, and were broken after cooling to room temperature to obtain a positive electrode material, and the Dv50 of the positive electrode material was 7 μm.

[0134] Example I4 group

[0135] The examples in this group were prepared according to Example I1, except that the molar ratio of the element M source calculated as element M to anhydrous sodium carbonate calculated as Na in step (1) was changed, specifically:

[0136] Example I4a, iron oxide calculated as Fe, nickel oxide calculated as Ni, manganese oxide calculated as Mn and anhydrous sodium carbonate calculated as Na were weighed and mixed in a molar ratio of 0.4:0.3:0.3:0.5;

[0137] Example I4b, iron oxide calculated as Fe, nickel oxide calculated as Ni, manganese oxide calculated as Mn and anhydrous sodium carbonate calculated as Na were weighed and mixed in a molar ratio of 0.4:0.3:0.3:0.9;

[0138] Example I4c, iron oxide calculated as Fe, nickel oxide calculated as Ni, manganese oxide calculated as Mn and anhydrous sodium carbonate calculated as Na were weighed and mixed in a molar ratio of 0.4:0.3:0.3:0.

[0139] Example I5 group

[0140] The examples in this group were prepared according to Example I1, except that the ratio of the mass of the solvent to the total mass of the element M source and anhydrous sodium carbonate in step (1) was changed, specifically:

[0141] Example I5a, the obtained mixture was mixed with deionized water in a mass ratio of 1:0.5;

[0142] Example I5b, the obtained mixture was mixed with deionized water at a mass ratio of 1:9.5.

[0143] Example I6 group

[0144] The examples in this group were carried out according to Example I1, except that the selection of the solvent in step (1) was changed, specifically:

[0145] Example I6a, deionized water was replaced by anhydrous ethanol with the same mass;

[0146] Example I6a, deionized water was replaced by isopropanol with the same mass.

[0147] Example I7

[0148] According to Example I1, except that the selection of the first sodium source and the second sodium source was changed, specifically: anhydrous sodium carbonate in step (1) was replaced by sodium dihydrogen phosphate with the same mass, and anhydrous sodium carbonate in step (3) was replaced by sodium dihydrogen phosphate with the same mass.

[0149] Example I8

[0150] The positive electrode material was prepared according to the following steps:

[0151] (1) Anhydrous sodium carbonate calculated as sodium, ammonium metavanadate calculated as vanadium, and ammonium dihydrogen phosphate calculated as phosphorus were weighed according to a molar ratio of 0.3:2:3, and the obtained mixture was mixed with deionized water at a mass ratio of 1:2, and was added into a sand mill, until the median particle size Dv50 of the milled material was 300 nm;

[0152] (2) The slurry prepared in step (1) was pumped into a spray dryer using a peristaltic pump, and the inlet air temperature was set to 250℃, the atomizer speed was 30000 rpm, the feeding speed was 80 ml / min, and the outlet air temperature was 100℃, to obtain a positive electrode material precursor;

[0153] (3) The positive electrode material precursor prepared in step (2) (calculated as sodium) and anhydrous sodium carbonate (calculated as sodium) were mixed uniformly according to a molar ratio of 0.3:2.76, and were sintered using a box furnace, with a sintering program of 450℃ for 2h and 800℃ for 10h, a sintering atmosphere of nitrogen, and a heating rate of 3℃ / min, and were broken after cooling to room temperature to obtain a positive electrode material, and the Dv50 of the positive electrode material was 1μm.

[0154] Comparative Example D1

[0155] The positive electrode material was prepared according to the following steps:

[0156] (1) Iron oxide calculated as Fe, nickel oxide calculated as Ni, manganese oxide calculated as Mn and sodium carbonate calculated as Na were weighed and mixed in a molar ratio of 0.4:0.3:0.3:1.05, and the obtained mixture was mixed with deionized water in a mass ratio of 1:2, and was added into a sand mill until the median particle size Dv50 of the sand-milled material was 300 nm;

[0157] (2) The slurry prepared in step (1) was pumped into a spray dryer using a peristaltic pump, and the inlet air temperature was set to 250°C, the atomizer speed was set to 30000 rpm, the feeding speed was set to 80 ml / min, and the outlet air temperature was set to 100°C to obtain the positive electrode material precursor;

[0158] (3) The sintering was performed using a box furnace, and the sintering program was 450°C for 2 h and 950°C for 12 h, the sintering atmosphere was air, and the heating rate was 3°C / min. After cooling to room temperature, the positive electrode material was obtained by crushing, and the Dv50 of the positive electrode material was 5 μm.

[0159] Comparative Example D2

[0160] The positive electrode material was prepared according to the following steps:

[0161] (1) Anhydrous sodium carbonate calculated as Na, ammonium metavanadate calculated as V and ammonium dihydrogen phosphate calculated as P were weighed and mixed in a molar ratio of 3.06:2:3, and the obtained mixture was mixed with deionized water in a mass ratio of 1:2, and was added into a sand mill until the median particle size Dv50 of the sand-milled material was 300 nm;

[0162] (2) The slurry prepared in step (1) was pumped into a spray dryer using a peristaltic pump, and the inlet air temperature was set to 250°C, the atomizer speed was set to 30000 rpm, the feeding speed was set to 80 ml / min, and the outlet air temperature was set to 100°C to obtain the positive electrode material precursor;

[0163] (3) The sintering was performed using a box furnace, and the sintering program was 450°C for 2 h and 800°C for 10 h, the sintering atmosphere was nitrogen, and the heating rate was 3°C / min. After cooling to room temperature, the positive electrode material was obtained by crushing, and the Dv50 of the positive electrode material was 1 μm.

[0164] Test Example I

[0165] (1) Electron Microscope Image

[0166] The positive electrode material precursor prepared in step (2) in Example I1, Example I4c, Example I7, Comparative Example D1 and Comparative Example D2 was subjected to electron microscope testing, and the test results are shown in Figure 1 wherein Figure 1 (a) is the electron microscope image of the positive electrode material precursor prepared in Example I1, Figure 1(b) the mirror image of the positive electrode material precursor prepared in Example 4c, Figure 1 (c) the mirror image of the positive electrode material precursor prepared in Example 7, Figure 1 (d) the mirror image of the positive electrode material precursor prepared in Comparative Example D1, Figure 1 (e) the mirror image of the positive electrode material precursor prepared in Comparative Example D2, from which it can be seen that the positive electrode material precursor prepared by the method of the present application has good balling effect and high particle integrity.

[0167] (2) Bulk density test

[0168] The positive electrode material precursors prepared in step (2) of the examples and comparative examples were subjected to bulk density test, and the results are recorded in Table 1.

[0169] Group II examples and comparative examples

[0170] The battery was prepared according to the following steps:

[0171] The positive electrode material, polyvinylidene fluoride and conductive carbon black prepared in Group I examples and comparative examples were mixed uniformly in a mass ratio of 8:1:1, added with N-methylpyrrolidone, and the obtained mixture was fully stirred uniformly using a mechanical centrifugal stirrer to obtain a positive electrode slurry (with a solid content of 45wt%); the above positive electrode slurry was uniformly coated on an aluminum foil by a coating machine, and placed in a 100°C oven for vacuum drying for 12h; a dicing machine was used to cut into circular electrode pieces with a diameter of 12mm, weighed, and the active material mass was calculated to be about 10mg;

[0172] The assembly of the battery was carried out in a glove box with oxygen <0.1ppm and water content <0.1ppm, with sodium sheet as the negative electrode, glass fiber membrane as the separator (whatman GF / D), and electrolyte being a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 1:1, to which 1mol / L of NaClO4 was added, to assemble into a 2032 type button cell.

[0173] Test example II

[0174] The batteries prepared in Group II examples and comparative examples were subjected to electrochemical performance test, and the specific test method was as follows:

[0175] The constant current charge-discharge test and long cycle test (100T) of the battery were realized by using a new CT4008 charge-discharge tester, and the test voltage window was 2V-4.0V, and the test results are recorded in Table 1.

[0176] Table 1

[0177]

[0178] As can be seen from Table 1, the tap density of the positive electrode material precursor prepared by the method of the present application is significantly improved compared with the comparative example, and the battery prepared from the positive electrode material has higher initial efficiency and cycle capacity retention rate compared with the comparative example.

Claims

1. A method for preparing a cathode material, characterized in that, The method includes the following steps: (1) Mix element M source, solvent and optional first sodium source, and mill; (2) The slurry obtained in step (1) is spray-dried to obtain the cathode material precursor; (3) Mix the cathode material precursor obtained in step (2) with the second sodium source and sinter; The molar ratio of the first sodium source (calculated as sodium) to the element M source (calculated as element M) is (0.05-0.9):1; the molar ratio of the second sodium source (calculated as sodium) to the element M source (calculated as element M) is (0.15-2):

1.

2. The method according to claim 1, wherein, The molar ratio of the first sodium source (calculated as sodium) to the element M source (calculated as element M) is (0.05-0.5):

1.

3. The method according to claim 2, wherein, The molar ratio of the first sodium source (calculated as sodium) to the element M source (calculated as element M) is (0.05-0.2):

1.

4. The method according to claim 1, wherein, The ratio of the total mass of the element M source and the first sodium source to the mass of the solvent is 1:(0.5-9.5). And / or, the solvent includes at least one of deionized water, anhydrous ethanol and isopropanol.

5. The method according to claim 4, wherein, The ratio of the total mass of the element M source and the first sodium source to the mass of the solvent is 1:(1.5-4). And / or, the solvent includes deionized water.

6. The method according to claim 1, wherein, The element M source includes at least one of copper, iron, manganese, nickel, cobalt, titanium, magnesium, aluminum, and vanadium sources; And / or, the first sodium source includes at least one of sodium carbonate, sodium dihydrogen phosphate, sodium hydroxide, sodium acetate, and sodium oxalate.

7. The method according to claim 6, wherein, The element M source includes at least one of the following: copper oxide, iron oxide, manganese oxide, nickel oxide, cobalt oxide, titanium oxide, magnesium oxide, aluminum oxide, and vanadium oxide. And / or, the first sodium source includes at least one of sodium carbonate, sodium hydroxide, sodium acetate, and sodium oxalate.

8. The method according to claim 1, wherein, In step (1), the addition of element R source is also included; the R source includes at least one of phosphorus source, sulfur source, silicon source, arsenic source, molybdenum source and tungsten source; And / or, the molar ratio of the first sodium source (calculated as sodium), the element M source (calculated as element M), and the element R source (calculated as element R) is (0.05-0.9):1:(1-3).

9. The method according to claim 1, wherein, The median particle size Dv50 of the material after sand milling is 100nm-800nm; And / or, the spray drying conditions are: inlet air temperature of 200℃-280℃, atomizer speed of 25000rpm-35000rpm, feed rate of 50ml / min-130ml / min, and outlet air temperature of 95℃-120℃.

10. The method according to claim 1, wherein, The median particle size Dv50 of the spray-dried cathode material precursor is 5μm-25μm; And / or, the solvent content of the spray-dried cathode material precursor is ≤5% by mass; And / or, the loose packing density of the spray-dried cathode material precursor is ≥0.6 g / cm³. 3 .

11. The method according to claim 10, wherein, The median particle size Dv50 of the spray-dried cathode material precursor is 10μm-15μm; And / or, the solvent content of the spray-dried cathode material precursor is ≤3% by mass; And / or, the loose packing density of the spray-dried cathode material precursor is ≥0.8 g / cm³. 3 .

12. The method according to claim 1, wherein, The second sodium source includes at least one of sodium carbonate, sodium dihydrogen phosphate, sodium hydroxide, sodium acetate, and sodium oxalate.

13. A positive electrode material, characterized in that, The cathode material is prepared by the method described in any one of claims 1-12.

14. The cathode material according to claim 13, wherein, The cathode material includes materials with the chemical formula Na. x M 1 O2 has the substance and / or chemical formula Na y M 2 z (RO4)3 substances; M 1 Selected from at least one of Cu, Fe, Mn, Ni, Co and V, where 0.6 ≤ x ≤ 1; M 2 It is selected from at least one of Cu, Fe, Mn, Ni, Co and V, and R is selected from at least one of S, P, Si, As, Mo and W, 1≤y≤3, 1≤z≤2.

15. A battery, characterized in that, The battery comprises the positive electrode material as described in claim 13 or 14.

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