Sodium ion battery positive electrode active material and its manufacturing method and use

Abstract

The present invention discloses a sodium ion battery positive electrode active material and its preparation and use. The chemical formula of the sodium ion battery positive electrode active material is Na x Ni y Fe z Mn g M h A m O 2 where M is one or more selected from the group consisting of Ti, Al, Mg, Ca, Zr, Y, Zn, Nb, and W, and A is one or more selected from the group consisting of B, P, and C, and 0.80≦x≦1.40, 0.05≦y≦0.95, 0.05≦z≦0.95, 0.05≦g≦0.95, 0.01≦h≦0.50, and 0.01≦m≦0.30. The present invention adds element M and element A to a ternary iron manganese nickel sodium ion battery positive electrode active material, and at the same time, controls the ratio of each element, thereby realizing the formation of a complete layered single crystal structure of the sodium ion battery positive electrode active material, and realizing a large-particle, ultimately stable active material, which is used in a sodium ion battery to ensure a higher gram capacity, and the cycle performance at high temperature is greatly improved.

Description

[Technical field]

[0001] The present invention relates to the field of sodium ion batteries, and in particular to a sodium ion battery positive electrode active material and its preparation method and use. [Background technology]

[0002] Lithium-ion batteries are widely used in the fields of electric vehicles, medium and large energy storage power stations, electric motorcycles, electric tools, portable electronic devices, etc. However, the explosive growth of lithium-ion batteries in the fields of electric vehicles and medium and large energy storage power stations has led to the structural problem of lithium resource shortages, which has caused the price of lithium salts to soar and the cost of lithium-ion batteries to soar. Sodium-ion batteries have similar electrochemical properties to lithium-ion batteries, and because sodium-ion batteries are abundant in resources and low in cost, they have become a popular development target in recent years and are expected to be widely used in the fields of electric motorcycles and medium and large energy storage power stations.

[0003] Due to the large radius of sodium ions, the positive electrode active materials selected for sodium ion batteries are relatively limited, and currently, the positive electrode active materials for sodium ion batteries with potential applications include three systems: Prussian blue, layered oxides, and polyanions. Among them, the layered oxide system with O3 structure is similar to the ternary positive electrode active materials of lithium ion batteries, and has the advantages of large capacity and high compact density, and is therefore regarded as the most potential positive electrode material and has been adopted by domestic and foreign sodium ion battery companies.

[0004] Chinese patent CN109817970A discloses a method for producing a monocrystalline sodium ion battery electrode material, which comprises mixing and reacting a mixed aqueous solution of iron salt, manganese salt, M salt, a precipitant, a complexing agent and a dispersant, and the resulting solid is the precursor of the battery electrode material, and the precursor is mixed with sodium salt, sintered and cooled to obtain a monocrystalline sodium ion battery electrode material, in which the dispersant is ammonium polyacrylate. If the above specific ammonium polyacrylate dispersant is not used, the crystal shape of the crystal grains is not obvious, and it is not possible to form a large single crystal at the micron level, and the discharge capacity and capacity retention rate of the corresponding battery electrode material are also low.

[0005] Although layered oxide positive electrode active materials exhibit excellent electrochemical properties, the large-scale commercial use of such active materials is significantly restricted due to the existence of problems such as many structural phase transitions during the charge and discharge process, poor air storage performance, high surface alkalinity, and side reactions with the electrolyte. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Chinese patent CN109817970A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to provide a positive electrode active material for a sodium ion battery that can ensure excellent capacity per gram performance of a sodium ion battery, improve cycle performance at high temperatures, and at the same time form a stable single crystal structure and have low surface alkalinity, in view of the shortcomings of the prior art. [Means for solving the problem]

[0008] In order to solve the above technical problems, the present invention adopts the following technical solutions. A sodium ion battery positive electrode active material, the positive electrode active material having the chemical formula Na x Ni y Fe z Mn g M h A m O2, where M is one or a combination of more selected from the group consisting of Ti, Al, Mg, Ca, Zr, Y, Zn, Nb, and W, A is one or a combination of more selected from the group consisting of B, P, and C, and 0.80≦x≦1.40, 0.05≦y≦0.95, 0.05≦z≦0.95, 0.05≦g≦0.95, 0.01≦h≦0.50, 0.01≦m≦0.30.

[0009] According to some preferred and specific aspects of the present invention, the compound of formula Na x Ni y Fe z Mn g M h A m In O2, 0.90≦x≦1.20 and 1.2-(y+z+g+h)≧0.

[0010] According to some preferred and specific aspects of the present invention, the compound of formula Na x Ni y Fe z Mn g M h A m In O2, 0.95≦x≦1.05, 0.1≦y≦0.5, 0.1≦z≦0.6, 0.1≦g≦0.5, 0.01≦h≦0.3, and 0.01≦m≦0.2.

[0011] According to some preferred and specific aspects of the present invention, the compound of formula Na x Ni y Fe z Mn g M h A m In O2, 0.98≦x≦1.03, 0.1≦y≦0.4, 0.2≦z≦0.5, 0.1≦g≦0.4, 0.01≦h≦0.2, and 0.01≦m≦0.1.

[0012] In some embodiments of the present invention, the M is one or a combination of a plurality of elements selected from the group consisting of Ti, Mg, and Ca, and the A is two or three elements selected from the group consisting of B, P, and C. do. In some embodiments of the present invention, A is a combination of three types of B, P, and C, The molar ratio of B, P and C is 2-4:0.1-1.5:0.1-1.5. In some embodiments of the present invention, A is a combination of two types of B and P, and the molar ratio of B to P is 2-4:0.1-1.5.

[0013] In some embodiments of the present invention, the positive electrode active material has a layered single crystal structure with an average particle size of 1 to 30 microns.

[0014] In some embodiments of the present invention, the tap density of the positive electrode active material is 1.33 to 2.5 g / cm 3 and the pH value is below 12.6.

[0015] Through research, the inventor has found that by adding element M and element A to the positive electrode active material of a sodium ion battery, and at the same time controlling the ratio of elements sodium, nickel, iron, manganese and elements M, A, O, the positive electrode active material of a sodium ion battery can be made to form a complete layered single crystal structure, and this active material can form large particles, the particles grow densely, the tap density of the active material is greatly increased, and the material has a low pH value, low surface alkalinity, stable surface properties, and less side reaction with the electrolyte; at the same time, under the premise of ensuring that it can exert a higher gram capacity when used in a sodium ion battery, the cycle performance at high temperature can be greatly improved.

[0016] In the sodium ion battery positive electrode active material of the present invention, each element plays a different role, among which the elements Ni and Mn allow the sodium ion battery to exhibit higher gram capacity. The element Fe has the dual effect of exhibiting gram capacity and improving the material discharge voltage, the element M improves the stability of the active material, the element B promotes the active material to form a large particle single crystal structure and improves the tap density of the material, and the element P can improve the high temperature cycle performance of the active material. In addition, each element also has a synergistic interaction and functions with each other, so that the sodium ion battery positive electrode active material of the present invention exhibits each of the above excellent performances. This significantly improves cycle performance at high temperatures.

[0017] The present invention also provides a method for producing the above-mentioned sodium ion battery positive electrode active material, the method comprising the steps of: (1) reacting a nickel salt, a manganese salt, and a hydroxide in the presence of a complexing agent to produce nickel manganese hydroxide; (2) adding water to nickel manganese hydroxide, an iron source, a compound containing element M, a compound containing element A, and a sodium source to form a slurry, and then sanding the slurry to obtain a mixed slurry; and (3) drying and sintering the mixed slurry to obtain the sodium ion battery positive electrode active material.

[0018] Furthermore, the chemical formula of the nickel manganese hydroxide in step (1) is Ni a Mn b (OH)2, where 0.05≦a≦0.95, 0.05≦b≦0.95, 1-ab ≧ 0.

[0019] Furthermore, the nickel salt in step (1) is one or a combination of more selected from the group consisting of nickel sulfate, nickel chloride, and nickel nitrate, the manganese salt is one or a combination of more selected from the group consisting of manganese sulfate, nickel chloride, and nickel nitrate, the hydroxide is one or two selected from the group consisting of sodium hydroxide and potassium hydroxide, and the complexing agent is one or a combination of more selected from the group consisting of ethylenediamine, ethylenediaminetetraacetic acid, tartaric acid, citric acid, oxalic acid, and aqueous ammonia.

[0020] In some embodiments of the present invention, in step (1), a nickel salt and a manganese salt are prepared into an aqueous metal salt solution, and then an aqueous hydroxide solution and a complexing agent are mixed to obtain a mixed solution, and the mixed solution is reacted at pH 9-12, 40-70°C, and under stirring to produce nickel manganese hydroxide.

[0021] More preferably, the total concentration of nickel ions and manganese ions in the aqueous metal salt solution is 0.5 to 2 mol / L. R .

[0022] More preferably, the stirring speed is 500-1200 r / min, and after the reaction, the mixture is aged, washed and dried to obtain Ni. a Mn b (OH)2 is obtained.

[0023] In some embodiments of the present invention, the iron source in step (2) is one or a combination of one or more selected from the group consisting of ferrous oxide, ferric oxide, and ferric oxide, and the sodium source is one or two selected from sodium carbonate and sodium hydroxide.

[0024] In some embodiments of the present invention, the compound containing element M in step (2) is selected from the group consisting of titanium dioxide, aluminum oxide, magnesium oxide, calcium oxide, calcium carbonate, zirconium oxide, yttrium oxide, zinc oxide, and niobium oxide. and Tungsten oxide A group consisting ofSelected from It is one or a combination of several The compound containing element A is one or a combination of more than one selected from the group consisting of boric acid, boron oxide, sodium tetraborate, diphosphorus pentoxide, phosphoric acid, sodium phosphate, sodium hypophosphite, glucose, sucrose, polyethylene glycol, and polyvinyl alcohol.

[0025] In some embodiments of the present invention, in step (2), the niobium The ratio of the total molar amount of nickel and manganese in the nickel manganese hydroxide, iron in the iron source, element M in the compound containing element M, and element A in the compound containing element A to the molar amount of sodium in the sodium source is 1:0.90 to 1.20.

[0026] In some embodiments of the present invention, in step (2), the sanding time is 0.5 to 8 hours, the abrasives are zirconium oxide balls having a particle size of 0.1 to 0.8 mm, and the sanding speed is 800 to 3000 rpm.

[0027] In some embodiments of the present invention, the mixed slurry has a solid content of 10% to 60%, and the median particle size of the particles in the mixed slurry is 20 to 800 nm.

[0028] In some embodiments of the present invention, in step (3), the drying is spray drying, and the rotation speed of the atomizing disk of the spray drying apparatus is 1000-3000 rpm, the inlet air temperature is 150-300°C, and the outlet air temperature is 80-120°C.

[0029] In some embodiments of the present invention, in step (3), the sintering is performed in air, the sintering temperature is 750 to 1000° C., and the sintering time is 5 to 25 hours. Preferably, the sintering is followed by pulverization.

[0030] In the manufacturing method of the present invention, in the case of elements Ni and Mn, which are easy to form uniform precipitates, the reaction activity can be improved by using their hydroxides as raw materials, and in the case of elements Fe and M, which are difficult to form uniform precipitates, the oxides or compounds containing element M can be used as raw materials to ensure the stability of the corresponding element contents. Sanding after mixing nickel manganese hydroxide, compound containing element M, compound containing element A, and sodium source can ensure that various elements are sufficiently and uniformly mixed, and spray drying can ensure that various raw materials do not segregate during the molding process.

[0031] The present invention also provides the use of the above-mentioned sodium ion battery positive electrode active material for use in a sodium ion battery positive electrode.

[0032] The present invention also provides a sodium ion battery positive electrode material, comprising a positive electrode active material, an adhesive and a conductive agent, wherein the positive electrode active material comprises the above-mentioned sodium ion battery positive electrode active material.

[0033] The present invention also provides a sodium ion battery positive electrode made by the aforementioned sodium ion battery positive electrode material.

[0034] The present invention also provides a sodium-ion battery comprising a positive electrode, the positive electrode comprising the sodium-ion battery positive electrode described above. Effect of the Invention

[0035] Compared with the prior art, the present invention has the following technical advantages: The positive electrode active material of the sodium ion battery of the present invention can form a complete layered single crystal structure, and its single crystal particles are large and densely grown, so that the tap density of the positive electrode active material is greatly increased, and the material has a low pH value, stable surface properties, and few side reactions with the electrolyte. At the same time, when used in a sodium ion battery, under the premise of ensuring a higher gram capacity, the cycle performance at high temperature can be greatly improved. The manufacturing method of the present invention makes it possible to mass-produce a sodium ion battery positive electrode active material with excellent performance in a stable manner. [Brief description of the drawings]

[0036] [Figure 1] FIG. 2 is a scanning electron microscope image of NaNi0.25Fe0.4Mn0.25Ti0.05B0.05O2 produced in Example 1. [Diagram 2] FIG. 2 is an XRD diagram of NaNi0.25Fe0.4Mn0.25Ti0.05B0.05O2 produced in Example 1. [Diagram 3] FIG. 2 is a charge / discharge curve diagram of NaNi0.25Fe0.4Mn0.25Ti0.05B0.05O2 produced in Example 1. [Figure 4] FIG. 1 is a cycle diagram of NaNi0.25Fe0.4Mn0.25Ti0.05B0.05O2 produced in Example 1 at 2.0 to 4.0 V / 1C at high temperature (60° C.). [Diagram 5] FIG. 2 is a scanning electron microscope image of NaNi0.25Fe0.40Mn0.25Ti0.03B0.05P0.02O2 produced in Example 2. [Figure 6] FIG. 2 is an XRD diagram of NaNi0.25Fe0.40Mn0.25Ti0.03B0.05P0.02O2 produced in Example 2. [Figure 7] FIG. 2 is a charge / discharge curve diagram of NaNi0.25Fe0.40Mn0.25Ti0.03B0.05P0.02O2 produced in Example 2. [Figure 8] FIG. 1 is a cycle diagram of NaNi0.25Fe0.40Mn0.25Ti0.03B0.05P0.02O2 produced in Example 2 at 2.0 to 4.0 V / 1C at high temperature (60° C.). [Figure 9] FIG. 2 is a scanning electron microscope image of NaNi0.25Fe0.45Mn0.25Ti0.05O2 produced in Comparative Example 1. [Figure 10] FIG. 1 is an XRD diagram of NaNi0.25Fe0.45Mn0.25Ti0.05O2 produced in Comparative Example 1. [Figure 11]FIG. 2 is a charge / discharge curve diagram of NaNi0.25Fe0.45Mn0.25Ti0.05O2 produced in Comparative Example 1. [Figure 12] FIG. 1 is a cycle diagram of NaNi0.25Fe0.45Mn0.25Ti0.05O2 produced in Comparative Example 1 at 2.0 to 4.0 V / 1C and high temperature (60° C.). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] In order to better understand the contents of the present invention, the following will be further described with reference to specific examples and the accompanying drawings. However, it should be understood that these examples do not limit the scope of the present invention, but are only used to further explain the invention. Furthermore, after reading the contents of the present invention, it should be understood that various improvements and adjustments made to the present invention by those skilled in the art without departing from the principle of the present invention are still within the protection scope of the present invention. In the following, unless otherwise specified, all raw materials are commercially obtained.

[0038] In the following examples and comparative examples, the charge / discharge curve and high-temperature cycle performance tests were performed using the following method. First, a sodium ion battery was manufactured. 20 g of the prepared positive electrode active material was weighed out, 0.64 g of conductive agent SP and 0.64 g of PVDF dissolved in NMP were added, and the mixture was mixed uniformly and then applied to an aluminum foil to manufacture an electrode plate. In a glove box with an argon gas atmosphere, a button battery was assembled using a metal sodium sheet as the negative electrode, Celgard2700 as the diaphragm, and 1 mol / L NaPF6+EC:DEC(1:1)+5%FEC as the electrolyte. Next, the charge / discharge curve was tested at a voltage range of 2.0 to 4.0 V, a charge and discharge rate of 0.1 C, a current of 13 mA, and a test temperature of 25±2° C., and the cycle performance was tested for 100 cycles at a voltage range of 2.0 to 4.0 V, a charge and discharge rate of 1 C, a current of 130 mA, and 60° C.

[0039] Example 1 This embodiment provides a sodium ion battery positive electrode active material, the chemical formula of which is NaNi 0.25 Fe0.4 Mn 0.25 Ti 0.05 B 0.05 O2, and the manufacturing method is Step (1) of adding nickel sulfate and manganese sulfate to pure water in a Ni:Mn molar ratio of 1:1 to prepare a solution having a total concentration of metal elements of 1.3 mol / L; Step (2) of preparing a 4.0 mol / L sodium hydroxide solution and a 5.0 mol / L aqueous ammonia solution; Step (3) is to add the metal salt solution obtained in step (1), the sodium hydroxide solution obtained in step (2), and the aqueous ammonia solution to the reaction vessel at a rate of 2.5 L / h, 1.5 L / h, and 0.2 L / h, respectively, and control the reaction temperature to 50°C, the reaction pH to 11.5, and the stirring speed to 650 rpm to react for 12 hours to obtain a precursor. The precursor was washed with pure water, filtered, dried, and then Ni 0.5 Mn 0.5 Step (4) to give (OH) 2.0 mol Ni 0.5 Mn 0.5 Step (5) of taking (OH)2, 0.8 mol of Fe2O3, 0.2 mol of TiO2, 0.2 mol of H3BO3, and 2.0 mol of Na2CO3 and adding all the raw materials to 3.5 L of water to prepare a slurry; Step (5) is put into a sand mill and polished for 3 hours, the polishing body is a zirconium oxide ball with a particle size of 0.2 mm, the sanding rotation speed is 2500 rpm, and a mixed slurry with an average particle size of about 350 nm is obtained by polishing; and step (6) is Step (7) includes transferring the mixed slurry obtained in step (6) to a stirring tank, stirring thoroughly, and adding pure water to prepare a slurry with a solid content of 30±1%, and spray-drying the mixture under the conditions of an atomization frequency of 35Hz, an inlet air temperature of 190°C, and an outlet air temperature of 85°C; sintering the dried product in an air atmosphere furnace at 850-940°C for 12 hours, cooling it to below 80°C, and pulverizing it with a jaw crusher and a roll to obtain a sodium ion battery positive electrode active material, the sample name of which is NFM242-TB.

[0040] The scanning electron microscope image of NFM242-TB is shown in FIG. 1, which shows that the material has a single crystal appearance. The XRD of NFM242-TB is shown in FIG. 2, which shows that the material has a pure phase layered structure of α-NaFeO2 type. The charge / discharge curve of NFM242-TB is shown in FIG. 3, which shows that the discharge capacity at 0.1C magnification is 124.8mAh / g in the voltage window of 2.0-4.0V. The high temperature cycle diagram of NFM242-TB is shown in FIG. 4, which shows that the capacity retention after 100 cycles at 60℃ and 1C magnification is 89.04% in the voltage window of 2.0-4.0V.

[0041] Example 2 The chemical formula of the sodium ion battery positive electrode active material of this embodiment is NaNi 0.25 Fe 0.40 Mn 0.25 Ti 0.03 B 0.05 P 0.02 It's O2.

[0042] The manufacturing method was basically the same as in Example 1, with the difference being that step (5) was replaced with 2.0 mol of Ni 0.5 Mn 0.5 Just take (OH)2, 0.8mol Fe2O3, 0.12mol TiO2, 0.2mol H3BO3, 0.08mol H3PO4, 2.0mol Na2CO3 and replace all the raw materials with 3.5L water to prepare a slurry. The sample name is NFM242-TBP.

[0043] The scanning electron microscope image of NFM242-TBP is shown in FIG. 5, which shows that the material has a single crystal appearance. The XRD of NFM242-TBP is shown in FIG. 6, which shows that the material has a pure phase layered structure of α-NaFeO2 type. The charge / discharge curve of NFM242-TBP is shown in FIG. 7, which shows that the discharge capacity at 0.1C magnification is 125mAh / g in the voltage window of 2.0-4.0V. The high temperature cycle diagram of NFM242-TBP is shown in FIG. 8, which shows that the capacity retention after 100 cycles at 60℃ and 1C magnification is 93.31% in the voltage window of 2.0-4.0V.

[0044] Example 3 The chemical formula of the sodium ion battery positive electrode active material of this embodiment is NaNi 0.25 Fe 0.4 Mn 0.25 Ti 0.05 P 0.05 It's O2.

[0045] The manufacturing method was basically the same as in Example 1, with the difference being that step (5) was replaced with 2.0 mol of Ni 0.5 Mn 0.5 Just take (OH)2, 0.8mol Fe2O3, 0.20mol TiO2, 0.2mol H3PO4, 2.0mol Na2CO3 and add all the raw materials to 3.5L water to prepare a slurry. By sanding, spray drying, sintering, grinding with jaw crush and roll, the final sodium ion battery positive electrode active material NaNi 0.25 Fe 0.4 Mn 0.25 Ti 0.05 P 0.05 O2 was obtained and the sample designation was NFM242-TP.

[0046] Example 4 The chemical formula of the sodium ion battery positive electrode active material of this embodiment is NaNi 0.25 Fe 0.4 Mn 0.25 Ca 0.05 B 0.05 It's O2.

[0047] The manufacturing method was basically the same as in Example 1, with the difference being that step (5) was replaced with 2.0 mol of Ni 0.5 Mn 0.5 All we had to do was take 0.1mol Fe2O3, 0.8mol CaCO3, 0.2mol H3BO3, 2.0mol Na2CO3, and add all the raw materials to 3.5L of water to prepare a slurry. After sanding, spray drying, sintering, jaw crushing and roll grinding, the final sodium ion battery positive electrode active material NaNi 0.25 Fe 0.4 Mn 0.25 Ca 0.05 B 0.05 O2 was obtained and the sample designation was NFM242-CaB.

[0048] Example 5 The chemical formula of the sodium ion battery positive electrode active material of this embodiment is NaNi 0.25 Fe 0.4 Mn 0.25 Ca 0.05 P 0.05 It's O2.

[0049] The manufacturing method was basically the same as in Example 1, with the difference being that step (5) was replaced with 2.0 mol of Ni 0.5 Mn 0.5 All we had to do was take 0.1mol Fe2O3, 0.8mol CaCO3, 0.2mol H3PO4, 2.0mol Na2CO3, and add all the raw materials to 3.5L of water to prepare a slurry. After sanding, spray drying, sintering, jaw crushing and roll grinding, the final sodium ion battery positive electrode active material NaNi 0.25 Fe 0.4 Mn 0.25 Ca 0.05 P 0.05 O2 was obtained and the sample designation was NFM242-CaP.

[0050] Example 6 The chemical formula of the sodium ion battery positive electrode active material of this embodiment is NaNi 0.25 Fe 0.40 Mn 0.25Ca 0.03 B 0.05 P 0.02 It's O2.

[0051] The manufacturing method was basically the same as in Example 1, with the difference being that step (5) was replaced with 2.0 mol of Ni 0.5 Mn 0.5 Just take (OH)2, 0.8mol Fe2O3, 0.12mol CaCO3, 0.2mol H3BO3, 0.08mol H3PO4, 2.0mol Na2CO3 and add all the raw materials to 3.5L water to prepare a slurry. By sanding, spray drying, sintering, grinding with jaw crush and roll, the final sodium ion battery positive electrode active material NaNi 0.25 Fe 0.40 Mn 0.25 Ca 0.03 B 0.05 P 0.02 O2 was obtained and the sample designation was NFM242-CaBP.

[0052] Comparative Example 1 The procedure is basically the same as in Example 1, except that step (5) is replaced with 2.0 mol of N i 0.5 Mn 0.5 Just take (OH)2, 0.9mol Fe2O3, 0.2mol TiO2, 2.0mol Na2CO3 and add all the raw materials to 3.5L water to prepare a slurry. By sanding, spray drying, sintering, grinding with jaw crush and roll, the final sodium ion battery positive electrode active material NaNi 0.25 Fe 0.45 Mn 0.25 Ti 0.05 O2 was obtained and the sample designation was NFM242-T.

[0053] The scanning electron microscope diagram of NFM242-T is shown in FIG. 9, which shows that the material has a loose globular structure aggregated from small primary granules and cannot form a single crystal structure. The XRD diagram of NFM242-T is shown in FIG. 10, which shows that the material is a pure phase layered structure of α-NaFeO2 type. The charge / discharge curve diagram of NFM242-T is shown in FIG. 11, which shows that in the voltage window of 2.0-4.0V, the discharge capacity at 0.1C magnification is 126.6mAh / g. The high temperature cycle diagram of NFM242-T is shown in FIG. 12, which shows that in the voltage window of 2.0-4.0V, the capacity retention after 100 cycles at 60℃ and 1C magnification is 82.8%.

[0054] Comparative Example 2 The procedure is basically the same as in Example 1, except that step (5) is replaced with 2.0 mol of Ni 0.5 Mn 0.5 Just take (OH)2, 0.9mol Fe2O3, 0.2mol CaCO3, 2.0mol Na2CO3 and add all the raw materials to 3.5L water to prepare a slurry. By sanding, spray drying, sintering, jaw crushing and roll grinding, the final sodium ion battery positive electrode active material NaNi 0.25 Fe 0.45 Mn 0.25 Ca 0.05 O2 was obtained and the sample designation was NFM242-Ca.

[0055] Comparative Example 3 The procedure is basically the same as in Example 1, except that step (5) is replaced with 2.0 mol of Ni 0.5 Mn 0.5 Just take (OH)2, 1.0 mol Fe2O3, 2.0 mol Na2CO3 and add all the raw materials to 3.5L of water to prepare a slurry. By sanding, spray drying, sintering, jaw crushing and roll grinding, the final sodium ion battery positive electrode active material NaNi 0.25 Fe 0.50 Mn 0.25 O2 was obtained and the sample designation was NFM252.

[0056] Performance Testing The positive electrode active materials obtained in the above Examples 1 to 7 and Comparative Examples 1 to 3 were subjected to physicochemical performance tests, and the pH value test method was as follows: 5 g of the prepared layered oxide positive electrode material was weighed out, dispersed in 50 ml of deionized water, stirred with a magnetic stirrer for 5 minutes, and allowed to stand at 25°C for 30 minutes, after which the mixture was filtered and the pH value of the filtrate was tested with a pH meter. The physicochemical performance results are shown in Table 1 below.

[0057] [Table 1]

[0058] The positive electrode active materials obtained in the above Examples 1 to 7 and Comparative Examples 1 to 2 were used in the sodium ion battery performance test, and the manufacturing method of the sodium ion battery was as follows: 20 g of the prepared positive electrode active material was weighed out, 0.64 g of conductive agent SP and 0.64 g of PVDF dissolved in NMP were added, and the mixture was mixed uniformly and then applied to an aluminum foil to manufacture an electrode plate. In a glove box with an argon gas atmosphere, a button battery was assembled using a metal sodium sheet as the negative electrode, Celgard2700 as the diaphragm, and 1 mol / L NaPF6+EC:DEC(1:1)+5%FEC as the electrolyte. Next, the charge and discharge curves were tested at a voltage range of 2.0 to 4.0 V, a charge and discharge rate of 0.1 C, a current of 13 mA, and a test temperature of 25 ± 2°C, and the cycle performance was tested for 100 cycles at a voltage range of 2.0 to 4.0 V, a charge and discharge rate of 1 C, a current of 130 mA, and 60°C. The test results are shown in Table 2.

[0059] [Table 2]

[0060] From Tables 1-2 above, it can be seen that, by adding elements B and P to the positive electrode active material of a sodium ion battery and controlling the ratio of all elements, the positive electrode active material can form a completely layered single crystal structure, and the single crystal particles are large and densely grown, the tap density of the positive electrode active material is greatly increased, and the pH value is reduced. When the positive electrode active material is used in a sodium ion battery, the cycle performance at high temperature can be greatly improved under the premise of ensuring a higher gram capacity.

[0061] The above examples are intended to explain the technical concepts and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and to implement it according to the present invention. These examples do not limit the protection scope of the present invention, and all equivalent changes and modifications made based on the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. The positive electrode active material has the chemical formula Na ｘ Ni ｙ Fe ｚ Mn ｇ M ｈ A ｍ O ２ wherein M is one or a combination of a plurality of elements selected from the group consisting of Ti, Al, Mg, Ca, Zr, Y, Zn, Nb, and W; A is a combination of two elements, B and P; the molar ratio of B:P is 2-4:0.1-1.5; and 0.80≦x≦1.40, 0.05≦y≦0.95, 0.05≦z≦0.95, 0.05≦g≦0.95, 0.01≦h≦0.50, and 0.01≦m≦0.

30.

2. The chemical formula Na ｘ Ni ｙ Fe ｚ Mn ｇ M ｈ A ｍ O ２ 2. The sodium ion battery positive electrode active material according to claim 1, wherein 0.90≦x≦1.20 and 1.2-(y+z+g+h)≧0.

3. The chemical formula Na ｘ Ni ｙ Fe ｚ Mn ｇ M ｈ A ｍ O ２ 2. The sodium ion battery positive electrode active material according to claim 1, wherein 0.95≦x≦1.05, 0.1≦y≦0.5, 0.1≦z≦0.6, 0.1≦g≦0.5, 0.01≦h≦0.3, and 0.01≦m≦0.

2.

4. The chemical formula Na ｘ Ni ｙ Fe ｚ Mn ｇ M ｈ A ｍ O ２ 2. The sodium ion battery positive electrode active material according to claim 1, wherein 0.98≦x≦1.03, 0.1≦y≦0.4, 0.2≦z≦0.5, 0.1≦g≦0.4, 0.01≦h≦0.2, and 0.01≦m≦0.

1.

5. 2. The sodium ion battery positive electrode active material according to claim 1, wherein M is one or a combination of a plurality of elements selected from the group consisting of Ti, Mg, and Ca.

6. The positive electrode active material has a layered single crystal structure with an average particle size of 1 to 30 microns; or The tap density of the positive electrode active material is 1.33 to 2.5 g / cm ３ 2. The sodium ion battery positive electrode active material according to claim 1, characterized in that the pH value is 12.6 or less.

7. (1) reacting a nickel salt, a manganese salt, and a hydroxide in the presence of a complexing agent to produce nickel manganese hydroxide; (2) adding water to nickel manganese hydroxide, an iron source, a compound containing element M, a compound containing element A, and a sodium source to prepare a slurry, and then sanding the slurry to obtain a mixed slurry; and (3) drying and sintering the mixed slurry to obtain the sodium ion battery positive electrode active material. The method for producing a sodium ion battery positive electrode active material according to any one of claims 1 to 6.

8. The chemical formula of the nickel manganese hydroxide in step (1) is Ni ａ Mn ｂ (OH) ２ where 0.05≦a≦0.95, 0.05≦b≦0.95, 1−a−b≧0, or The method for producing a positive electrode active material for a sodium ion battery according to claim 7, characterized in that in step (2), the ratio of the total molar amount of nickel and manganese in the nickel manganese hydroxide, iron in the iron source, element M in the compound containing element M, and element A in the compound containing element A to the molar amount of sodium in the sodium source is 1:0.90 to 1.

20.

9. The nickel salt in step (1) is one or a combination of a plurality of salts selected from the group consisting of nickel sulfate, nickel chloride, and nickel nitrate, the manganese salt is one or a combination of a plurality of salts selected from the group consisting of manganese sulfate, manganese chloride, and manganese nitrate, the hydroxide is one or two salts selected from the group consisting of sodium hydroxide and potassium hydroxide, and the complexing agent is one or a combination of a plurality of salts selected from the group consisting of ethylamine, ethylenediaminetetraacetic acid, tartaric acid, citric acid, oxalic acid, and aqueous ammonia, or In step (2), the iron source is one or a combination of two or more selected from the group consisting of ferrous oxide, ferric oxide, and ferric oxide, and the sodium source is one or two selected from sodium carbonate and sodium hydroxide, or The compound containing the element M in step (2) is one or a combination of a plurality of compounds selected from the group consisting of titanium dioxide, aluminum oxide, magnesium oxide, calcium oxide, calcium carbonate, zirconium oxide, yttrium oxide, zinc oxide, niobium oxide, and tungsten oxide, and the compound containing the element A is a combination of a plurality of compounds selected from the group consisting of boric acid, boron oxide, sodium tetraborate, diphosphorus pentoxide, phosphoric acid, sodium phosphate, sodium hypophosphite, glucose, sucrose, polyethylene glycol, and polyvinyl alcohol. The method for producing a positive electrode active material for a sodium ion battery according to claim 7.

10. In step (1), a nickel salt and a manganese salt are prepared into an aqueous metal salt solution, and then an aqueous hydroxide solution and a complexing agent are mixed to obtain a mixed solution, and the mixed solution is reacted at pH 9-12, 40-70° C. and under stirring to generate nickel manganese hydroxide; or In step (2), the sanding time is 0.5-8 h, the abrasive is a zirconium oxide ball with a particle size of 0.1-0.8 mm, and the sanding speed is 800-3000 rpm; or The median particle size of the particles in the mixed slurry is 20-800 nm, and the solid content of the mixed slurry is 10%-60%; or In step (3), the drying is spray drying, and the rotation speed of the atomizing disk of the spray drying device is 1000-3000 rpm, the inlet air temperature is 150-300° C., and the outlet air temperature is 80-120° C.; In step (3), the sintering is performed in air, and the sintering temperature is 750 to 10 8. The method for producing a positive electrode active material for a sodium ion battery according to claim 7, wherein the temperature is 0° C. and the time is 5 to 25 hours.

11. A sodium ion battery positive electrode material comprising a positive electrode active material, an adhesive, and a conductive agent, the positive electrode active material comprising the sodium ion battery positive electrode active material according to any one of claims 1 to 6.

12. A sodium ion battery positive electrode, which is manufactured by the sodium ion battery positive electrode material according to claim 11.

13. 12. A sodium ion battery comprising a positive electrode, the positive electrode comprising the sodium ion battery positive electrode of claim 11.

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