Positive electrode material for sodium ion battery and method for producing the same, sodium ion battery

Abstract

The air stability and structural stability of the cathode material are improved under the premise of ensuring high volumetric energy density, and when the cathode material is applied to a sodium-ion battery, the electrochemical performance of the sodium-ion battery is effectively improved. The present invention relates to the technical field of sodium-ion batteries, and more particularly to a cathode material for sodium-ion batteries, a manufacturing method thereof, and a sodium-ion battery. In the XRD pattern of the cathode material, characteristic diffraction peaks A and B corresponding to the (003) crystal plane and the (104) crystal plane, respectively, are present at 2θ angles of 15-19° and 39-44°. The crystallite size D of the characteristic diffraction peak A is A and the crystallite size D of the characteristic diffraction peak B B However, 1.3≦D A / D B Meets ≦2.5. D A and D B correspond to the crystallite sizes in the directions perpendicular to the (003) and (104) crystal planes, respectively.

Description

[Technical Field]

[0001] The present invention relates to the technical field of sodium ion batteries, and more particularly to a positive electrode material for sodium ion batteries, a manufacturing method thereof, and a sodium ion battery equipped with the positive electrode material for sodium ion batteries. [Background technology]

[0002] In recent years, with the production and use of electric vehicles, lithium-ion batteries have been widely used in the new energy vehicle industry, but as the price of lithium resources continues to rise, sodium-ion batteries, which are abundant and low-cost, have attracted widespread attention. Sodium-ion battery technology can significantly reduce battery manufacturing costs and is expected to be widely applied in the fields of low-speed electric vehicles and energy storage.

[0003] In sodium-ion battery systems, currently, layered oxides (Na x MO2 (where M=Ni, Fe, Mn, etc.) is a cathode material that meets the application requirements of power and energy storage batteries, and has the advantages of low cost, excellent low-temperature performance, high thermal stability, good safety performance, high energy density, and low environmental impact. Layered oxides have great potential in markets such as medium and low-end passenger cars and energy storage batteries.

[0004] However, Na x MO2 materials are very sensitive to air humidity, and moisture absorption can easily cause conversion, which deteriorates their stability in air. In addition, Na + As Na enters and leaves the structure, a large volume change occurs, which causes the structure to collapse and deteriorates circulation stability. x The problem to be solved by the present invention is how to overcome the drawbacks of MO2 material and improve its air stability and structural stability. Summary of the Invention [Problem to be solved by the invention]

[0005] To solve the above technical problems, the present invention proposes a positive electrode material for a sodium ion battery, a manufacturing method thereof, and a sodium ion battery, thereby improving the air stability and structural stability of the positive electrode material under the premise of ensuring a high volumetric energy density, and by applying the positive electrode material to a sodium ion battery, the electrochemical performance of the sodium ion battery can be effectively improved. [Means for solving the problem]

[0006] To achieve the above object, a first aspect of the present invention proposes a cathode material for a sodium-ion battery. In the XRD pattern of the cathode material, characteristic diffraction peaks A and B corresponding to the (003) crystal plane and the (104) crystal plane are present at 2θ angles of 15-19° and 39-44°, respectively. The crystallite size D of the characteristic diffraction peak A is A and the crystallite size D of the characteristic diffraction peak B B is 1.3≦D A / D B Meets ≦2.5. D A and D B represent the crystallite sizes in the directions normal to the (003) and (104) crystal planes, respectively.

[0007] In the present invention, unless otherwise specified, the positive electrode material of a sodium-ion battery is referred to as the positive electrode material.

[0008] Preferably, the positive electrode material has an O3 type single crystal structure and a c value is selected from the range of 16-16.1 Å.

[0009] Preferably, the positive electrode material has the composition shown in Formula I: Na a (Ni x Fe y Mn z M m M' n)O2(I), wherein in formula I, 0.8≦a≦1.1, 0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5, 0≦m≦0.5, 0≦n≦0.2, 0.05≦m+n≦0.5, m and n are not simultaneously 0, and x+y+z+m+n=1; M and M' are each independently selected from at least one of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La.

[0010] In a second aspect of the present invention, a method for manufacturing a cathode material for a sodium-ion battery is provided, which includes the following steps:

[0011] (1) Ni α Fe β Mn γ M δ O a H b A precursor having the composition shown in (II) is pre-calcined to obtain a pre-calcined precursor.

[0012] (2) The pre-calcined precursor and Na source are mixed with an optional M'-containing dopant and calcined to obtain a cathode material.

[0013] In the positive electrode material, M and M' are not 0 at the same time.

[0014] In formula II, 0≦α≦0.5, 0≦β≦0.5, 0≦γ≦0.5, 0≦δ≦0.5, 1≦a≦2, 0≦b≦2, α+β+γ+δ=1, and M and M′ are selected from at least one of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La.

[0015] The pre-firing includes a first temperature-raising step, a second temperature-raising step, and a temperature-holding step, wherein the conditions for the first temperature-raising step include raising the temperature to T1 at a temperature-raising rate v1 in an oxygen-deficient atmosphere having an oxygen concentration of ≦10 vol%, the conditions for the second temperature-raising step include raising the temperature to T2 at a temperature-raising rate v2 in an oxygen-deficient atmosphere having an oxygen concentration of ≦20 vol%, and the conditions for the temperature-holding step include holding the temperature for t within a temperature range (T2−10)≦T≦(T2+10), where v1 is selected from 5-10°C / min, v2 is selected from 1-3°C / min, T1 is selected from 200-300°C, T2 is selected from 450-750°C, and t is selected from 3-10 h.

[0016] In a second aspect of the present invention, there is proposed a sodium-ion battery comprising the cathode material proposed in the first aspect or a cathode material produced according to the production method proposed in the second aspect. [Effects of the Invention]

[0017] The present invention has the following beneficial effects compared to the current technology.

[0018] (1) The positive electrode material according to the present invention is provided with a characteristic diffraction peak A and a characteristic diffraction peak B, which are respectively associated with the crystal plane and the (104) crystal plane of the positive electrode material, and in addition, D A / D B By keeping the c value within a reasonable range, the distance of Na+ transport during the charge / discharge process is shortened, making transport easier and improving the charge / discharge performance. Furthermore, by keeping the c value within a preferred range, the spacing between the sodium layers is kept relatively small, which not only does not affect the normal insertion / escape of Na+, but also prevents moisture and carbon dioxide in the air from entering between the layers and reacting with Na. In other words, this positive electrode material not only has high sodium ion mobility and significantly improved air stability, but also significantly increases the compaction degree of the positive electrode material by implementing the width distribution of large and small granules and the grading design of the precursor, thereby increasing the volumetric energy density of the material.

[0019] (2) In the manufacturing method according to the present invention, the precursor having the composition shown in Formula II is pre-calcined (i.e., the first temperature-rise step, the second temperature-rise step, and the temperature-holding step), which increases the tap density of the precursor, increases productivity, and enables the precursor to be completely dehydrated, thereby solving the problem of inconsistent physical phases of precursors with different compositions and facilitating the subsequent compounding and calcination processes. Furthermore, the treated pre-calcined precursor maintains its morphology while increasing its porosity and specific surface area, enhancing its reactivity and facilitating complete reaction with the sodium source during the subsequent sodium compounding and calcination process. This reduces residual alkalinity on the surface of the cathode material and improves its air stability.

[0020] By adjusting the particle size distribution and composition of the precursor and the doping element of the dopant, the present invention alleviates the volume change caused during the normal intercalation / extraction process of Na+, and thus adjusts the compaction density, volumetric energy density, and structural stability of the positive electrode material.

[0021] In summary, the preparation method of the present invention provides a pre-calcined precursor with high density and high reactivity, and a cathode material prepared by calcining the pre-calcined precursor has high air stability and good structural stability while ensuring a high volumetric energy density. In addition, it solves the problems of poor air stability and short cycle life of the cathode materials of existing layered oxide sodium ion batteries. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is an SEM image of the precursor obtained in Example 1.

[0023] [Figure 2] 1 is an SEM image of the pre-calcined precursor obtained in Example 1.

[0024] [Figure 3] 1 is an SEM image of the O3-type single crystal positive electrode material S1 obtained in Example 1.

[0025] [Figure 4] FIG. 1 is an XRD diagram of the precursor obtained in Example 1.

[0026] [Figure 5] FIG. 1 is an XRD diagram of the pre-calcined precursor obtained in Example 1.

[0027] [Figure 6] FIG. 1 is an XRD diagram of the O3-type single crystal positive electrode material S1 obtained in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] The endpoints of any ranges described herein and any value should not be understood to be limiting to the range or value, but rather to include ranges or values ​​close to the range or value. In the case of numerical ranges, the endpoints of each range may be combined, or each range endpoint may be combined with an individual point value, or each individual point value may be combined to obtain one or more new numerical ranges, and these numerical ranges are considered to be disclosed herein.

[0029] In the present invention, unless otherwise specified, the terms "first" and "second" do not indicate a priority, nor do they indicate a function of limiting individual materials or steps, but are used only to distinguish or explain that they are not the same material or step. For example, "first temperature-raising stage" and "second temperature-raising stage" are used only to indicate that they do not belong to the same temperature-raising stage.

[0030] In a first aspect of the present invention, a cathode material for a sodium-ion battery is proposed. In the XRD pattern of the cathode material, characteristic diffraction peaks A and B corresponding to the (003) crystal plane and the (104) crystal plane are present at 2θ angles of 15-19° and 39-44°, respectively. The crystallite size D of the characteristic diffraction peak A is A and the crystallite size D of the characteristic diffraction peak B B is 1.3≦D A / D B Meets ≦2.5. DA and D B represent the crystallite sizes in the directions normal to the (003) and (104) crystal planes, respectively.

[0031] In the present invention, unless otherwise specified, microcrystalline structure (e.g., D A and D B ) refers to the perpendicular distance from the crystal plane to the crystallite center. For example, D A is the perpendicular distance from the (003) crystal plane to the crystallite center, and D B is the perpendicular distance from the (104) crystal plane to the crystallite center.

[0032] In the present invention, the crystallite size is measured by the following method: The powder X-ray diffraction pattern is measured by powder X-ray diffraction using the powder X-ray diffraction pattern synthesis analysis software JADE 6.5. The half-peak widths of the characteristic diffraction peaks A and B in the range of 2θ = 15-19° and 2θ = 39-44°, respectively, are calculated, and the crystallite size D is calculated according to the Scherrer equation using the half-peak widths. A and crystallite size D B Calculate.

[0033] In the present invention, D A / D B The larger the ratio, the larger the difference in crystallite size in different directions, and the crystallites grow anisotropically, resulting in D A / D B The closer the ratio is to 1, the more consistent the crystallite sizes are in different directions, and the crystallites grow isotropically. When the crystallite volume is the same, the degree of anisotropic growth of the crystallites affects the intrusion / escape of sodium ions and the stability of the crystallites. Therefore, in the present invention, A / D B Ratio 1.3≦D A / D B ≦2.5, so that the transmission distance of Na+ during the charging and discharging process is shorter, the transmission is easier, and the multiplication performance is improved.

[0034] In some embodiments of the present invention, the positive electrode material preferably has an O3-type single crystal structure, and the c value is selected from the range of 16-16.1 Å. In the present invention, the smaller the interlayer spacing of the positive electrode material, the more restricted the c value range is, which prevents moisture and carbon dioxide in the air from entering the interlayer spacing and reacting with Na when the material is exposed to a humid environment, thereby significantly improving air stability.

[0035] In the present invention, the term "O3-type single crystal structure" refers to a single crystal cathode material that is O3-type in crystal form, that is, the cathode material has the crystal lattice structure parameters of O3-type sodium electrolytic layered oxide.

[0036] In the present invention, unless otherwise specified, the characteristic diffraction peak A has a single broad peak within the 2θ range of 15-19°, and the characteristic diffraction peak B has a single broad peak within the 2θ range of 39-44°.

[0037] In some embodiments of the present invention, preferably, in the XRD pattern of the positive electrode material, the 2θ of the characteristic diffraction peak A is 16.5±1°, and the 2θ of the characteristic diffraction peak B is 41.5±1°.

[0038] In one specific embodiment of the present invention, when X-ray diffraction measurement is performed on the positive electrode material using CuKα radiation, the crystallite size D of the characteristic diffraction peak A in the range of 2θ=16.5±1° is A and the crystallite size D of the characteristic diffraction peak B within the 2θ=41.5±1° range. B However, 1.3≦D A / D B Meets ≦2.5.

[0039] In some embodiments of the present invention, the crystallite size D of the characteristic diffraction peak A A and the crystallite size D of the characteristic diffraction peak B B is 1.3≦D A / D BFor example, the crystallite size can be 1.3, 1.5, 1.8, 2, 2.5, and any value in the range between any two values, preferably 1.3≦D A / D B ≦2.

[0040] In some embodiments of the present invention, the positive electrode material preferably has the composition shown in Formula I: Na a (Ni x Fe y Mn z M m M' n )O2(I), wherein in formula I, 0.8≦a≦1.1, 0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5, 0≦m≦0.5, 0≦n≦0.2, 0.05≦m+n≦0.5, m and n are not simultaneously 0, and x+y+z+m+n=1; M and M' are each independently selected from at least one of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La.

[0041] In some embodiments of the present invention, it is more preferred that Formula I has a range of 0.85≦a≦1.05, and even more preferably 0.93≦a≦1.03.

[0042] In some embodiments of the present invention, more preferably, in Formula I, M is selected from at least one of Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Nb, Y, W, and La, and M' is selected from at least one of Li, Al, Mg, Ti, Zr, Sr, La, Nb, B, and W. Preferably, M and M' are different.

[0043] In some embodiments of the present invention, the average particle size D of the cathode material is preferably 50 is 7-20 μm, preferably 8-16 μm, and more preferably 9-12 μm.

[0044] In the present invention, the positive electrode material has a wide particle size distribution. Preferably, the particle size distribution of the positive electrode material is 1.2≦(D 90 -D 10 ) / D 50For example, the particle size distribution can be 1.2, 1.4, 1.5, 1.6, 1.8, and any value in the range between any two values, and preferably 1.4≦(D 90 -D 10 ) / D 50 ≦1.6. Meeting the above particle size distribution helps to increase the compaction degree and volumetric energy density of the positive electrode material.

[0045] In some embodiments of the present invention, the positive electrode material preferably has a compaction density of 3-3.6 g / cm 3 For example, the compaction rate is 3 g / cm 3 , 3.3g / cm 3 , 3.4g / cm 3 , 3.5g / cm 3 , 3.6g / cm 3 , and any value in the range between any two values, preferably 3.3-3.6 g / cm 3 is.

[0046] In some embodiments of the present invention, the positive electrode material water increment Δ(H2O)=H2O(t x -t0) / H2O(t0), 0h <t x ≦6h, t0=0h satisfies 0%≦Δ(H2O)≦120%, and preferably 0%≦Δ(H2O)≦100%.

[0047] In some embodiments of the present invention, the residual alkalinity conversion rate of the cathode material, Δ(Na2CO3 + NaOH) = Na2CO3 (t x -t0) / Na2CO3(t0)+NaOH(t x -t0) / NaOH(t0), 0h <t x ≦6h, t0=0h satisfies 0%≦Δ(Na2CO3+NaOH)≦200%, and preferably 0%≦Δ(Na2CO3+NaOH)≦150%.

[0048] As the interlayer spacing of the positive electrode material increases, moisture and carbon dioxide in the air can easily enter the layer structure and react with Na, leading to increased moisture absorption in the material, an increased conversion of Na2CO3 to NaOH, and a significant shift in the diffraction peak of the (003) crystal plane. In the present invention, the interlayer spacing of the positive electrode material is rationally arranged to ensure easier intercalation / exit of sodium ions, and also to prevent moisture and carbon dioxide in the air from entering the interlayer spacing, resulting in reduced moisture absorption in the air and reduced conversion of Na2CO3 to NaOH. Therefore, the positive electrode material provided by the present invention has excellent air stability.

[0049] In a second aspect of the present invention, a method for manufacturing a cathode material for a sodium-ion battery is provided, which includes the following steps:

[0050] (1) Ni α Fe β Mn γ M δ O a H b A precursor having the composition shown in (II) is pre-calcined to obtain a pre-calcined precursor.

[0051] (2) The pre-calcined precursor and Na source are mixed with an optional M'-containing dopant and calcined to obtain a cathode material.

[0052] In the positive electrode material, M and M' are not 0 at the same time.

[0053] In formula II, 0≦α≦0.5, 0≦β≦0.5, 0≦γ≦0.5, 0≦δ≦0.5, 1≦a≦2, 0≦b≦2, α+β+γ+δ=1, and M and M′ are selected from at least one of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La.

[0054] The pre-firing includes a first temperature-raising step, a second temperature-raising step, and a temperature-holding step, wherein the conditions for the first temperature-raising step include raising the temperature to T1 at a temperature-raising rate v1 in an oxygen-deficient atmosphere having an oxygen concentration of ≦10 vol%, the conditions for the second temperature-raising step include raising the temperature to T2 at a temperature-raising rate v2 in an oxygen-deficient atmosphere having an oxygen concentration of ≦20 vol%, and the conditions for the temperature-holding step include holding the temperature for t within a temperature range (T2−10)≦T≦(T2+10), where v1 is selected from 5-10°C / min, v2 is selected from 1-3°C / min, T1 is selected from 200-300°C, T2 is selected from 450-750°C, and t is selected from 3-10 h.

[0055] In the present invention, the specific pre-calcination process specifically limits the oxygen content, heating rate, temperature, and time of the first heating step, second heating step, and heat-holding step, thereby increasing the tap density of the precursor, increasing production capacity, and enabling the precursor to be completely dehydrated, thereby solving the problem of physical phase inconsistency between precursors with different compositions and facilitating the subsequent blending and calcination processes. Furthermore, the pre-calcined precursor obtained through the specific pre-calcination process maintains its morphology while increasing its porosity and specific surface area, enhancing its reactivity and facilitating complete reaction with the sodium source during the subsequent sodium blending and calcination process. This reduces residual alkali on the surface of the cathode material and improves its air stability.

[0056] In the present invention, unless otherwise specified, the fact that M and M' in the positive electrode material are not simultaneously 0 refers to the fact that, in the manufacturing method of the positive electrode material, when the M angle in the precursor having the composition shown in Formula II is marked as 0, an M'-containing dopant must be added; when the M angle in the precursor having the composition shown in Formula II is not marked as 0 when no M'-containing dopant is added; or when the M angle in the precursor having the composition shown in Formula II is not marked as 0, it does not matter whether an M'-containing dopant is added.

[0057] In some embodiments of the present invention, the precursor preferably has an average particle size D 50 is 7.5-8.5 μm, and the particle size distribution is 1≦(D 90-D 10 ) / D 50 ≦1.5. When the above parameters are satisfied, the compaction density and volumetric energy density of the positive electrode material are increased.

[0058] In some embodiments of the present invention, the precursor preferably has a tap density of 0.7-1.5 g / cm 3 and the specific surface area is 30-100m 2 / g.

[0059] In the present invention, the primary particles of the precursor are uniformly arranged in a vertical flake shape and have a dense surface. 50 When the particle size distribution, tap density and specific surface area are satisfied, the positive electrode material has the maximum compatible cycling performance and capacity.

[0060] In the present invention, the precursor can be selected from a wide range of sources as long as it has the composition shown in Formula II above. Preferably, the precursor is obtained by the following method: In a non-oxidizing atmosphere, a mixed metal salt solution containing a Ni source, an Fe source, a Mn source, and an M source, a precipitant solution, and a complexing agent solution are co-precipitated to obtain the precursor.

[0061] In the present invention, the non-oxidizing atmosphere includes, but is not limited to, a nitrogen atmosphere, a helium atmosphere, an argon atmosphere, etc., and is preferably a nitrogen atmosphere.

[0062] In some embodiments of the present invention, the amounts of the Ni source, Fe source, Mn source, and M source in the mixed metal salt solution satisfy n(Ni):n(Fe):n(Mn):n(M), where 0≦n(Ni)≦0.5, 0≦n(Fe)≦0.5, 0≦n(Mn)≦0.5, and 0≦n(M)≦0.5.

[0063] In some embodiments of the present invention, the concentration of the mixed metal salt solution, including the metal elements, is 1-5 mol / L, preferably 1-3 mol / L.

[0064] In one specific embodiment of the present invention, the Ni source is selected from at least one of nickel sulfate, nickel nitrate, and nickel chlorate, the Fe source is selected from at least one of iron sulfate, iron nitrate, and iron chlorate, the Mn source is selected from at least one of manganese sulfate, manganese nitrate, and manganese chlorate, and the M source is selected from at least one of sulfates, nitrates, and chlorates containing M, i.e., at least one of sulfates, nitrates, and chlorates containing Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La. Preferably, the M source is selected from at least one of sulfates, nitrates, and chlorates containing Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Nb, Y, W, and La.

[0065] In some embodiments of the present invention, the concentration of the precipitant solution is 3-10 mol / L. In the present invention, the precipitant in the precipitant solution is selected from common chemicals in the current technology, including but not limited to NaOH, KOH, LiOH, etc.

[0066] In some embodiments of the present invention, the concentration of the complexing agent is 2-11 mol / L. In the present invention, the complexing agent in the complexing agent solution is selected from commonly used agents in the current technology, including, but not limited to, aqueous ammonia, ammonium bicarbonate, ammonium carbonate, citric acid, disodium ethylenediaminetetraacetate, etc.

[0067] In some embodiments of the present invention, the co-precipitation reaction is preferably carried out intermittently, in which a mixed metal salt solution containing a Ni source, an Fe source, a Mn source, and an M source, a precipitant solution, and a complexing agent solution are fed into a reaction vessel using a metering pump within a certain period of time, and the reactants are discharged after the precipitate has completely crystallized and grown in the reaction vessel. Carrying out the co-precipitation reaction intermittently helps to obtain a precursor with a wide particle size distribution.

[0068] In some embodiments of the present invention, the co-precipitation reaction conditions preferably include a pH value of 10-12.5, a temperature of 40-80°C, a time of 48-120 hours, and a stirring speed of 100-800 rpm.

[0069] In some embodiments of the present invention, the precursor and the pre-calcined precursor preferably each independently have a spherical structure.

[0070] In the present invention, the product of the co-precipitation reaction is filtered under suction, and the obtained filter cake is dried at 100-140°C and then sieved to obtain the precursor.

[0071] In some embodiments of the present invention, preferably, in step (1), the pre-calcined product is sequentially filtered, washed, and dried to obtain a pre-calcined precursor.

[0072] In some embodiments of the present invention, in step (2), the dosage of the pre-calcined precursor and the Na source preferably satisfies n(Ni+Fe+Mn+M):n(Na)=0.8-1.1:1, such as 0.8:1, 0.85:1, 0.93:1, 0.95:1, 1:1, 1.03:1, 1.05:1, 1.1:1, and any value in the range between any two values. Preferably, n(Ni+Fe+Mn+M):n(Na)=0.85-1.05:1, more preferably n(Ni+Fe+Mn+M):n(Na)=0.93-1.03:1.

[0073] In some embodiments of the present invention, preferably, in step (2), the Na source is selected from at least one of sodium carbonate, sodium hydroxide, sodium nitrate, and sodium oxide.

[0074] In some embodiments of the present invention, the dopant is preferably selected from at least one of oxides, phosphates, carbonates, fluorides, chlorides, hydroxides and silicides containing element M', i.e., at least one of sulfates, nitrates and chlorates containing Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W and La, preferably Li, Al, Mg, Ti, Zr, Sr, La, The inorganic filler is selected from at least one of sulfates, nitrates and chlorates containing Nb, B and W, and is more preferably selected from Li2CO3, Al2O3, AlPO4, AlCl3, MgO, Mg3(PO4)2, MgCO3, MgSi2, MgF2, MgCl2, TiO2, ZrO, Zr(HPO4)2, ZrSi2, Sr(OH)2, SrCO3, SrSi2, SrF2, SrCl2, La2O3, Nb2O5, B2O3 and WO3.

[0075] In some embodiments of the present invention, preferably, in step (2), the firing conditions include a temperature selected from the range of 900 to 1100°C and a time selected from the range of 5 to 15 hours.

[0076] In some embodiments of the present invention, more preferably, the calcination comprises a temperature-rising stage I, a temperature-rising stage II, and a constant-temperature stage, wherein the difference in oxygen concentration between the atmosphere in the temperature-rising stage II and the atmosphere in the temperature-rising stage I is 10-100 vol%, and the difference in temperature-rising rate between the temperature-rising stage I and the temperature-rising stage II is 2-15°C / min.

[0077] In the present invention, unless otherwise specified, the difference between the oxygen concentration in the atmosphere in the temperature-rising stage II and the oxygen concentration in the atmosphere in the temperature-rising stage I being 10-100 vol% means that the oxygen concentration in the atmosphere in the temperature-rising stage II is higher than the oxygen concentration in the atmosphere in the temperature-rising stage I, and the difference between the two is 10-100 vol%. The difference between the temperature-rising rate in the temperature-rising stage I and the temperature-rising rate in the temperature-rising stage II being 2-15°C / min means that the temperature-rising rate in the temperature-rising stage I is higher than the temperature-rising rate in the temperature-rising stage II, and the difference between the two is 2-15°C / min.

[0078] In the present invention, unless otherwise specified, the difference between the oxygen concentration in the atmosphere in the temperature-rising stage II and the oxygen concentration in the atmosphere in the temperature-rising stage I being 10-100 vol% means that the oxygen concentration in the atmosphere in the temperature-rising stage II is higher than the oxygen concentration in the atmosphere in the temperature-rising stage I, and the difference between the two is 10-100 vol%. The difference between the temperature-rising rate in the temperature-rising stage I and the temperature-rising rate in the temperature-rising stage II being 2-15°C / min means that the temperature-rising rate in the temperature-rising stage I is higher than the temperature-rising rate in the temperature-rising stage II, and the difference between the two is 2-15°C / min.

[0079] In some embodiments of the present invention, the conditions for the temperature-raising stage I preferably include raising the temperature to T1' at a temperature-raising rate of v1' in an oxygen-deficient atmosphere having an oxygen concentration of ≦10 vol%, the conditions for the temperature-raising stage II preferably include raising the temperature to T2' at a temperature-raising rate of v2' in an atmosphere having an oxygen concentration of ≧20 vol%, and the conditions for the constant temperature stage preferably include maintaining the temperature within a temperature range of (T2'-10)≦T'≦(T2'+10) for t' time, where v1'≧3°C / min, v2'≦1°C / min, T1' selected from 600-800°C, T2' selected from 900-1100°C, and t' selected from 5-15 hours.

[0080] In some embodiments of the present invention, preferably, in step (2), the method comprises sequentially cooling, crushing, and sieving the calcined product to obtain the positive electrode material.

[0081] In the present invention, the positive electrode material produced according to the production method of the present invention has the composition shown in Formula I. a (Ni x Fe y Mn z M m M' n)O2(I), wherein Formula I has the following: 0.8≦a≦1.1, 0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5, 0≦m≦0.5, 0≦n≦0.2, 0.05≦m+n≦0.5, m and n are not simultaneously 0, and x+y+z+m+n=1; M and M' are each independently selected from at least one of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La. More preferably, Formula I has the following: 0.85≦a≦1.05; M' is selected from at least one of Li, Al, Mg, Ti, Zr, Sr, La, Nb, B, and W. Even more preferably, Formula I has the following: 0.93≦a≦1.03; and M is different from M'.

[0082] In a third aspect of the present invention, there is proposed a sodium-ion battery comprising the cathode material proposed in the first aspect or a cathode material produced according to the production method proposed in the second aspect.

[0083] The application of the positive electrode material in the present invention to a sodium ion battery can effectively improve the electrochemical performance of the sodium ion battery, especially the power consumption performance, cycling performance and volumetric energy density.

[0084] We will now explain the present invention in detail through examples.

[0085] (1) The compositions of the precursor, pre-calcined precursor, and cathode material are measured by ICP method. The equipment used is PE Optima 7000DV, and the measurement is performed according to the following conditions: 0.1g of sample is completely dissolved in 3mL of HNO3 + 9mL of HCl mixed acid solution, and then diluted to 250mL before testing.

[0086] (2) Observe the morphology of the material using a Hitachi S-4800 model scanning electron microscope (SEM).

[0087] (3) Measure the particle size of the precursor and cathode material using a Malvern particle size analyzer.

[0088] (4) The crystalline structure of the positive electrode material is measured using XRD. The equipment used is an X-ray diffractometer (Rigaku, Smart Lab 9KW). The measurement is performed under the following conditions: the X-ray source is Cu Kα radiation, the scanning range is 10° to 80°, the scanning speed is 1.2° / min, and the sampling width is 0.02°.

[0089] (5) The compaction degree of the positive electrode material is measured using the powder compression method. The required equipment is a powder compression machine (MCP-PD51), and the measurement condition is 20KN.

[0090] (6) Measure the tap density of the precursor using the fixed mass method, and measure the specific surface area of ​​the precursor using the BET specific surface area test method.

[0091] (7) Crystallite size ratio D A / D B The measurement method is as follows: The positive electrode material is packed into a special substrate, and semi-quantitative spectroscopic analysis is performed using CuKα radiation, with the diffraction angles set in the range of 2θA = 15-19° and 2θB = 39-44°, a scanning speed of 1.2° / min, and a sampling width of 0.02°, to obtain powder X-ray diffraction patterns of peaks A and B. The powder X-ray diffraction pattern synthesis analysis software JADE 6.5 is used to determine the half-peak widths of the characteristic diffraction peaks A in the range of 2θ = 15-19° and B in the range of 2θ = 39-44° that appear in the powder X-ray diffraction patterns measured by powder X-ray diffraction, and the crystallite size D is calculated using the half-peak widths according to the Scherrer equation. A and crystallite size D B is calculated, thus obtaining the crystallite size ratio.

[0092] (8) Electrochemical Performance Test: In the following examples and comparative examples, the electrochemical performance of the positive electrode material is tested using an R2025 button-type sodium ion battery.

[0093] The manufacturing process for a sodium-ion battery is as follows:

[0094] Electrode strip preparation: The positive electrode material for sodium ion batteries, the conductive agent SuperP, and polyvinylidene fluoride (PVDF) were thoroughly mixed with an appropriate amount of N-methylpyrrolidone (NMP) in a mass ratio of 90:5:5 to form a homogeneous paste. The slurry was applied to aluminum foil, dried at 120°C for 12 hours, and then pressed under a pressure of 100 MPa to prepare a positive electrode strip with a diameter of 12 mm and a thickness of 120 μm.

[0095] Battery assembly: In an argon-filled glove box with a moisture and oxygen content of less than 5 ppm, the positive electrode strip, diaphragm, negative electrode strip, and electrolyte were assembled into an R2025 button-type sodium-ion battery and allowed to stand for 6 hours. A 14 mm diameter, 1 mm thick metallic sodium sheet was used as the negative electrode strip, a 25 μm thick separator was used as the diaphragm, and 1 mol / L NaPF6 and a 4:6 mixture of methyl ethyl carbonate (EMC) and propylene carbonate (PC) were used as the electrolyte. <Electrochemical performance test>

[0096] In the following examples and comparative examples, the electrochemical performance of R2025 button-type sodium-ion batteries was tested using a Shenzhen Xinwei battery testing system (CT3008). The initial charge / discharge capacity test conditions were 0.1C@2-4.0V, 25°C, with a constant voltage cut-off current of 0.02C. The cycling performance test conditions were 1.0C@2-4.0V, 25°C. Constant-current charge / discharge tests were performed on the button-type sodium-ion batteries at 0.1C and 1C, respectively, to evaluate the specific charge / discharge capacity, cycling performance, and volumetric energy density of the sodium-ion battery cathode material. The higher the capacity retention rate during cycling, the more stable the material and the better the cycling performance of the battery system. Example 1

[0097] S1: Dissolve nickel sulfate, iron sulfate, manganese sulfate, and copper sulfate in a proportion where the molar ratio of nickel, iron, manganese, and copper elements is 20:30:40:10 to obtain a 2 mol / L mixed metal salt solution. Dissolve sodium hydroxide to obtain a precipitant solution with a concentration of 8 mol / L. Dissolve ammonia water to obtain a complexing agent solution with a concentration of 10.4 mol / L.

[0098] 100 L of the mixed metal salt solution, precipitant solution, and complexing agent solution were injected into the reactor in a parallel flow manner for coprecipitation, followed by controlled crystal growth of the precipitate in an overflow device under the protection of an argon atmosphere until the average particle size reached 8 μm. The precursor paste was filtered and washed, and the filter cake was dried at 120 °C and sieved to obtain the precursor (the composition and physical property parameters are shown in Table 1).

[0099] The co-precipitation reaction is carried out according to the following conditions: pH value is set to 12.38, and temperature is set to 60°C.

[0100] S2: Pre-calcining the pre-precursor, and allowing the pre-calcined product to cool naturally to obtain a pre-calcined precursor (the composition of which is shown in Table 1).

[0101] The first temperature rise stage is carried out under the condition that the temperature is raised from 25°C to T1 = 250°C at a temperature rise rate of v1 = 6°C / min in an oxygen-deficient atmosphere with an oxygen concentration of 10 vol%.

[0102] The second temperature-raising stage is carried out in an atmosphere with an oxygen concentration of 20 vol % under the conditions of raising the temperature from 250°C to T2 = 550°C at a temperature-raising rate of v2 = 2°C / min.

[0103] The heat-holding step is carried out according to the condition that the temperature is kept within the range of T=540-560° C. for t=4 h.

[0104] S3, the precursor is calcined with Na2CO3, cooled, crushed and sieved to obtain O3-type single crystalline cathode material S1 (composition, crystal type and physical property parameters are shown in Table 1).

[0105] The amounts of the pre-calcined precursor and the Na source satisfy n(Ni+Fe+Mn+Cu):n(Na)=1:0.96.

[0106] The temperature rising stage I is carried out under the condition that the temperature is raised from 25° C. to T1′=700° C. at a temperature rising rate of v1′=3° C. / min in an oxygen-deficient atmosphere with an oxygen concentration of 10 vol%.

[0107] The temperature-raising stage II is carried out under the condition that the temperature is raised from 700° C. to T2′=950° C. at a temperature-raising rate of v2′=1° C. / min in an atmosphere with an oxygen concentration of 20 vol%.

[0108] The constant temperature stage is carried out according to the condition that the temperature is kept within the temperature range of T'=950° C. for t'=15 h. <Experimental Example 2>

[0109] This example differs from the method of Experimental Example 1 in that in step S2, the temperature of the second heating stage is T2=450°C and the temperature of the heat-retention stage is T=440-460°C, but other conditions are the same, and an O3-type single crystalline positive electrode material S2 is obtained. <Experimental Example 3>

[0110] In this example, in step S3, the precursor is calcined with Na2CO3 and Al2O3, cooled, crushed, and sieved to obtain O3-type single crystalline positive electrode material S3 (the composition, crystal type, and physical property parameters are shown in Table 1). This is different from the method in Experimental Example 1 in that the amount of Al2O3 satisfies n(Al):n(Ni+Fe+Mn+Cu+Al)=0.05, but other conditions are the same, to obtain O3-type single crystalline positive electrode material S3. <Experimental Example 4>

[0111] This example differs from the method of Experimental Example 1 in that the time of the heat-keeping stage in step S2 is t=10 h, but other conditions are the same, and an O3-type single crystalline positive electrode material S4 is obtained. <Experimental Example 5>

[0112] This example differs from the method of Experimental Example 1 in that in step S2, the heating rate in the first heating stage is v1 = 10 °C / min and the heating rate in the second heating stage is v2 = 1 °C / min, but other conditions are the same, and O3-type single crystalline positive electrode material S5 is obtained. <Experimental Example 6>

[0113] In this embodiment, by controlling the crystal growth of the precipitate in step S1, the precursor particle size distribution is 90 =(D 90 -D 10 ) / D 50 = 1, but under the same conditions, an O3-type single crystalline cathode material S6 is obtained. <Experimental Example 7>

[0114] This example differs from the method of Experimental Example 1 in that in step S1, nickel sulfate, iron sulfate, manganese sulfate, and copper sulfate are dissolved in a proportion where the molar ratio of nickel, iron, manganese, and copper elements is 22:25:42:11 to obtain a 2 mol / L mixed metal salt solution, but other conditions are the same, and an O3-type single crystalline positive electrode material S7 is obtained. <Experimental Example 8>

[0115] In this embodiment, by controlling the crystal growth of the precipitate in step S1, the precursor particle size distribution is 90 =(D 90 -D 10 ) / D 50 = 0.8, but under the same conditions, an O3-type single crystalline cathode material S8 is obtained. <Comparative Example 1>

[0116] This comparative example differs from the method of experimental example 1 in that step S2 is omitted and the precursor prepared in step S1 is directly calcined in step S3, but other conditions are the same to obtain O3-type single crystalline positive electrode material DS1. <Comparative Example 2>

[0117] This comparative example differs from the method of experimental example 1 in that in step S2, the temperature of the second heating stage is T2 = 300°C and the temperature of the heat-retention stage is T = 290-310°C, but other conditions are the same, and an O3-type single crystalline positive electrode material DS2 is obtained. <Comparative Example 3>

[0118] This comparative example differs from the method of experimental example 1 in that in step S2, the temperature of the second heating stage is T2 = 1000 °C and the temperature of the heat-retention stage is T = 990-1010 °C, but other conditions are the same, and an O3-type single crystalline positive electrode material DS3 is obtained. <Comparative Example 4>

[0119] This comparative example differs from the method of Experimental Example 1 in that the time of the heat-retention stage in step S2 is t=1 h, but other conditions are the same, and an O3-type single crystalline positive electrode material DS4 is obtained. <Comparative Example 5>

[0120] This comparative example differs from the method of Experimental Example 1 in that the heating rate of the second heating stage in step S2 is v2 = 10 °C / min, but other conditions are the same, and an O3-type single crystalline positive electrode material DS5 is obtained. <Comparative Example 6>

[0121] This comparative example differs from the method of Experimental Example 1 in that the first heating step is omitted in step S2, and the precursor is directly heated from 250°C to T2 = 550°C at a heating rate of v2 = 2°C / min in an oxygen-deficient atmosphere with an oxygen concentration of 20 vol%. The temperature is then maintained within the temperature range of T = 540-560°C for t = 4 h. The other conditions are the same, and an O3-type single crystalline positive electrode material DS6 is obtained. [Table 1-1] [Table 1-2] [Table 1-3]

[0122] Note: 1- refers to the dosage of the Na source and pre-calcined precursor satisfying n(Na):n(Ni + Fe + Mn + Cu), and 2- refers to the dosage of the dopant satisfying n(M'):n(Ni + Fe + Mn + M + M'). [Table 1-4] [Table 1-5]

[0123] According to the results in Table 1, compared with Comparative Examples 1 to 6, the positive electrode materials prepared according to the method proposed in the present invention in Examples 1 to 8 had a D A / D B ≦2.5, especially 1.3≦D A / D B ≦2, and the c value is 16-16.1 Å.

[0124] Compared with Example 8, the particle size distribution of the precursors adjusted in Examples 1 to 7 was 1≦(D 90 -D 10 ) / D 50 ≦1.5, thereby effectively increasing the compaction degree of the positive electrode material and the volumetric energy density of the electrode made of the positive electrode material. <Test example> <(1) Morphological test>

[0125] The present invention provides scanning electron microscope images of the precursor, pre-calcined precursor, and O3-type single crystalline cathode material prepared in the above examples and comparative examples, and representatively provides SEM images of the precursor, pre-calcined precursor, and O3-type single crystalline cathode material S1 prepared in Example 1. The results are shown in Figures 1 to 3, respectively. As shown in Figure 1, the granules of the precursor have a broad particle size distribution, and the surfaces of large and small granules are dense. As shown in Figure 2, the pre-calcined precursor maintains the sphericity and width distribution of the precursor, and its surface is round and dense. As shown in Figure 3, the surfaces of large and small granules of O3 single crystalline cathode material S1 are round, the particle size distribution is broad, and the large granules are packed between the small granules, providing good grading function. <(2) Physical property test>

[0126] The present invention measured the XRD of the precursor, pre-calcined precursor, and O3-type single crystalline positive electrode material S1 prepared in the above examples and comparative examples, and provided representative XRD images of the precursor, pre-calcined precursor, and O3-type single crystalline positive electrode material S1 prepared in Example 1. The results are shown in Figures 4 to 6, respectively. According to Figure 4, the physical phase of the precursor is 1 / 4(Ni 0.2 Fe 0.3 Mn 0.4 Cu 0.1 )OOH@3 / 4(Ni 0.2 Fe 0.3 Mn 0.4 Cu 0.1 )O 4 / 3 According to Figure 5, the physical phase of the pre-calcined precursor is (Ni 0.2 Fe 0.3 Mn 0.4 Cu 0.1 )3O4 pure phase. According to Figure 6, the physical phase of the single crystal cathode material S1 is the O3-type layered oxide (Na 0.96 Ni 0.2 Fe 0.3 Mn 0.4 Cu 0.1 O2).

[0127] The O3 single crystal cathode material samples prepared in the above experimental examples and comparative examples were both placed in air with a relative humidity of 45% for 0-6 hours, and their precise moisture content, residual alkalinity and XRD characteristic diffraction peak parameters are shown in Table 2.

[0128] The amount of water increase is Δ(H2O) = H2O(t x -t0) / H2O(t0), 0h <t x ≦6h, t0=0h,

[0129] The conversion rate of the residual alkali is Δ(Na2CO3 + NaOH) = Na2CO3(t x -t0) / Na2CO3(t0)+NaOH(t x -t0) / NaOH(t0), 0h <t x ≦6h, t0=0h. [Table 2-1] [Table 2-2] [Table 2-3] [Table 2-4] [Table 2-5] [Table 2-6] [Table 2-7]

[0130] According to the data in Table 2, compared with Comparative Examples 1 to 6, the cathode materials prepared according to the preparation method of the present invention in Experimental Examples 1 to 8 absorb less moisture from the air, and the conversion of Na2CO3 to NaOH is also less. The amount of Na dehydrated by the reaction of moisture with carbon dioxide in the air is also less, the interlayer change is smaller, and the peak position of the characteristic diffraction peak A of the (003) crystal plane shifts inconspicuously forward.

[0131] Compared with Example 1, the positive electrode material prepared in Comparative Example 1 by directly calcining the precursor has a higher moisture absorption rate in the air and a higher conversion rate of Na2CO3 to NaOH.

[0132] Comparing Example 1 with Comparative Examples 2 to 6, it was found that the moisture increase and residual alkali conversion rate of the positive electrode material could be suppressed by adjusting the sintering treatment conditions, sintering temperature, heating rate, and sintering time. <(3) Electrochemical performance test>

[0133] In the present invention, the electrochemical performance of the positive electrode materials of the sodium ion batteries prepared in the above examples and comparative examples was tested. The specific test results, including the initial discharge specific capacity at 0.1C, the initial discharge specific capacity at 0.1C, the multiplication performance, the cycling performance and the volumetric energy density, are shown in Table 3. [Table 3]

[0134] According to the data in FIG. 3, the positive electrode material of the sodium ion battery according to the present invention is obtained by calcining the precursor through a specific sintering method, and the particle size distribution of the precursor is set to 1≦(D 90 -D 10 ) / D 50 If the particle size of the precursor is kept below 1.5, the obtained pre-sintered precursor has better structural stability and reactivity, and the cathode material made from the pre-sintered precursor has better air stability and structural stability. This can significantly improve the foldability and cycling performance of the cathode material for sodium-ion batteries, especially the medium particle size D of the precursor. 50 and particle size distribution K 90 By further limiting the amount of the dopant, the compaction degree of the positive electrode material of the sodium ion battery can be further increased, and the volumetric energy density can be increased. In addition, the doping element can further improve the foldability and cycling performance of the positive electrode material of the sodium ion battery.

[0135] Comparing Example 1 with Comparative Example 1, the material prepared by pre-calcining the precursor has better capacity and cycling performance. In other words, the pre-calcination technique proposed in the present invention helps to improve the structural stability and reaction activity of the material, and the sodium electrode material prepared thereby has comprehensive performances including higher capacity, higher capacity, and longer cycling compared to the sodium electrode material prepared directly from the precursor without pre-calcination treatment.

[0136] Comparing Example 1 with Comparative Examples 2 and 3, it can be seen that if the pre-baking temperature is kept within a preferred range, the obtained positive electrode material has better foldability, cycling performance and air stability.

[0137] Comparing Example 1 with Comparative Example 4, it was found that keeping the pre-baking time within a preferred range further strengthens the structural stability of the positive electrode material of the sodium ion battery, and further improves the rechargeability, cycling performance, and air stability.

[0138] Comparing Examples 1 and 5 with Comparative Example 5, it was found that controlling the temperature rise rate of the pre-baking within a preferred range further strengthens the structural stability of the positive electrode material of the sodium ion battery, and further improves the rechargeability, cycling performance, and air stability.

[0139] Comparing Example 1 with Comparative Example 6, the precursor pre-calcined in the second heating step was found to be superior in terms of expansion performance, cycling performance, and air stability compared to the precursor pre-calcined in the first heating step.

[0140] Comparing the test results of Examples 1 and 3, it can be seen that adding different doping elements to the positive electrode material of the sodium ion battery can further enhance the stability of the single crystal structure, and further improve the power supply performance and cycling performance of the positive electrode material of the sodium ion battery.

[0141] Comparing the test results of Example 1 and Example 8, it can be seen that if the particle size distribution of precursor A is outside the preferred range, the compaction degree of the positive electrode material for sodium ion batteries will be significantly reduced, and the volumetric energy density will also be reduced.

[0142] Crystallite size ratio D in Examples and Comparative Examples A / D B and the crystal lattice structure parameter c value, the positive electrode material made within the preferred condition range has a crystallite size ratio D A / D B When the σ is reduced to 1.3-2.5 and the c value is reduced to 16-16.1, superior magnification performance and significantly improved air stability are achieved compared to the comparative example.

[0143] Although the preferred embodiments of the present invention have been described in detail above, they are not limited to the present invention. Within the scope of the technical concept of the present invention, it is possible to carry out simple modifications to the technical means of the present invention and combine various technical features in other suitable ways, and such simple modifications and combinations should also be considered as the contents disclosed in the present invention, and all are included in the protection scope of the present invention.

Claims

1. In the XRD pattern of the positive electrode material, characteristic diffraction peaks A and B corresponding to the (003) crystal plane and the (104) crystal plane are present at 2θ angles of 15-19° and 39-44°, respectively. The crystallite size D of the characteristic diffraction peak A A and the crystallite size D of the characteristic diffraction peak B B However, 1.3≦D A / D B ≦2.5, D A and D B correspond to the crystallite sizes in the directions perpendicular to the (003) and (104) crystal planes, respectively. A positive electrode material for a sodium ion battery.

2. The cathode material has an O3-type single crystal structure with a c value selected from 16-16.1 Å; and / or In the XRD pattern of the positive electrode material, the characteristic diffraction peak A has an angle of 2θ of 16.5±1° and the characteristic diffraction peak B has an angle of 2θ of 41.5±1°; and / or The crystallite size D of the characteristic diffraction peak A A and the crystallite size D of the characteristic diffraction peak B B However, 1.3≦D A / D B Satisfies ≦2, The positive electrode material for a sodium ion battery according to claim 1.

3. The positive electrode material has a composition shown in Formula I: So a (Ni x Feb y Mr z M m M' n )O 2 (I) In formula I, 0.8≦a≦1.1, 0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5, 0≦m≦0.5, 0≦n≦0.2, 0.05≦m+n≦0.5, m and n are not simultaneously 0, and x+y+z+m+n=1; M and M′ are each independently selected from at least one element of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La; Preferably, in formula I, 0.85≦a≦1.05, more preferably 0.93≦a≦1.03; Preferably, in formula I, M is selected from at least one element of Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Nb, Y, W and La, and M' is selected from at least one element of Li, Al, Mg, Ti, Zr, Sr, La, Nb, B and W, more preferably, M and M' are different.

3. The positive electrode material for a sodium ion battery according to claim 1 or 2.

4. The average particle size D of the positive electrode material 50 is 7-20 μm, preferably 8-16 μm, more preferably 9-12 μm, and / or The particle size distribution of the positive electrode material is 1.2≦(D 90 -D 10 ) / D 50 ≦1.8, preferably 1.4≦(D 90 -D 10 ) / D 50 ≦1.6, and / or The compaction density of the positive electrode material is 3-3.6 g / cm 3 and preferably 3.3-3.6 g / cm 3 and / or The amount of water increase in the positive electrode material Δ(H 2 O)=H 2 O(t x -t 0 ) / H 2 O(t 0 ) is 0%≦Δ(H 2 O)≦120%, and preferably 0%≦Δ(H 2 O)≦100%, where 0h <t x ≦6h,t 0 = 0h, and / or The residual alkali conversion rate Δ(Na 2 CO 3 +NaOH) = Na 2 CO 3 (t x -t 0 ) / Na 2 CO 3 (t 0 )+NaOH(t x -t 0 ) / NaOH(t 0 ) is 0% or less Δ(Na 2 CO 3 +NaOH)≦200%, preferably 0%≦Δ(Na 2 CO 3 +NaOH)≦150%, where 0h<t x ≦6h,t 0 =0h, The positive electrode material for a sodium ion battery according to any one of claims 1 to 3.

5. (1) Ni α Fe β Mn γ M δ O a H b (II) pre-calcining a precursor having a composition shown in (II) to obtain a pre-calcined precursor; (2) mixing the pre-calcined precursor and a Na source with an optional M′-containing dopant and calcining to obtain a cathode material; Here, M and M' are not 0 at the same time, In formula II, 0≦α≦0.5, 0≦β≦0.5, 0≦γ≦0.5, 0≦δ≦0.5, 1≦a≦2, 0≦b≦2, α+β+γ+δ=1, M and M′ are selected from at least one element of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La; The pre-baking includes a first temperature-raising stage, a second temperature-raising stage, and a temperature-holding stage, and the conditions of the first temperature-raising stage are: in an oxygen-deficient atmosphere having an oxygen concentration of ≦10 vol%, v 1 At a heating rate of T 1 The second temperature-raising step includes heating the material to a temperature of v in an oxygen-deficient atmosphere having an oxygen concentration of ≦20 vol%. 2 At a heating rate of T 2 and the conditions of the heat-holding step are within a temperature range (T 2 -10)≦T≦(T 2 + 10) for t hours, where v 1 is selected from 5-10°C / min, and v 2 is selected from 1-3°C / min, and T 1 is selected from 200-300°C, and T 2 is selected from 450-750°C, and t is selected from 3-10h. A method for producing a positive electrode material for a sodium ion battery, comprising:

6. The average particle size D of the precursor in step (1) 50 is 7.5-8.5 μm, and the particle size distribution is 1≦(D 90 -D 10 ) / D 50 ≦1.5, and / or The precursor has a tap density of 0.7-1.5 g / cm 3 and the specific surface area is 30-100m 2 / g, and / or Obtaining the precursor by a method of co-precipitating a mixed metal salt solution containing a Ni source, an Fe source, a Mn source and an M source, a precipitant solution and a complexing agent solution in a non-oxidizing atmosphere; and / or the precursor and the pre-calcined precursor each independently have a spherical structure; The method according to claim 5 .

7. In step (2), the dosage of the pre-calcined precursor and the Na source satisfies n(Ni+Fe+Mn+M):n(Na)=0.8-1.1:1, preferably n(Ni+Fe+Mn+M):n(Na)=0.85-1.05:1, more preferably n(Ni+Fe+Mn+M):n(Na)=0.93-1.03:1; and / or the dosage of component C satisfies n(M'):n(Ni+Fe+Mn+M+M')=0-0.2:1, and / or The dopant is selected from at least one of oxides, phosphates, carbonates, fluorides, chlorides, hydroxides and silicides containing an element M', and preferably Li 2 CO 3 , Al 2 O 3 , AlPO 4 , AlCl 3 , MgO, Mg 3 (PO 4 ) 2 , MgCO 3 , MgSi 2 , MgF 2 , MgCl 2 , TiO 2 , ZrO, Zr(HPO 4 ) 2 , ZrSi 2 , Sr(OH) 2 , SrCO 3 , SrSi 2 , SrF 2 , SrCl 2 , La 2 O 3 , Nb 2 O 5 , B 2 O 3 and WO 3 At least one of The method according to claim 5 or 6.

8. In step (2), the firing conditions include a temperature selected from 900 to 1100°C and a time selected from 5 to 15 hours; and / or the firing includes a temperature-rising stage I, a temperature-rising stage II, and a constant temperature stage, the difference between the oxygen concentration in the atmosphere in the temperature-rising stage II and the oxygen concentration in the atmosphere in the temperature-rising stage I is 10-100 vol%, the difference between the temperature-rising rate in the temperature-rising stage I and the temperature-rising rate in the temperature-rising stage II is 2-15°C / min, Preferably, the conditions of the temperature-raising stage I are: in an oxygen-deficient atmosphere having an oxygen concentration of ≦10 vol%, v 1 At a heating rate of 'T' 1 ', and the conditions of the temperature-raising stage II include heating the mixture in an atmosphere having an oxygen concentration of 20 vol% or more to v 2 At a heating rate of 'T' 2 ', and the conditions of the constant temperature stage are within a temperature range (T 2 '-10)≦T'≦(T 2 '+10) for t' hours, where v 1 ' ≥ 3℃ / min, v 2 '≦1℃ / min, T 1 ' is selected from 600-800°C, T 2 ' is selected from 900-1100°C, and t' is selected from 5-15h; The manufacturing method according to any one of claims 5 to 7.

9. The positive electrode material has a composition shown in Formula I: So a (Ni x Feb y Mr z M m M' n )O 2 (I) In formula I, 0.8≦a≦1.1, 0≦x≦0.5, 0≦y≦0.5, 0≦z≦0.5, 0≦m≦0.5, 0≦n≦0.2, 0.05≦m+n≦0.5, m and n are not simultaneously 0, and x+y+z+m+n=1; M and M′ are each independently selected from at least one of Li, Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Sr, Nb, B, Y, W, and La; Preferably, in formula I, 0.85≦a≦1.05, more preferably, in formula I, 0.93≦a≦1.03; Preferably, in formula I, M is selected from at least one element of Cu, Co, V, Cr, Ti, Mg, Sn, Zn, Al, Zr, Nb, Y, W and La, and M' is selected from at least one element of Li, Al, Mg, Ti, Zr, Sr, La, Nb, B and W, more preferably, M and M' are different. The manufacturing method according to any one of claims 5 to 8.

10. The cathode material according to any one of claims 1 to 5 or the cathode material produced according to the production method according to any one of claims 6 to 9, A sodium-ion battery characterized by:

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