A sodium-ion battery positive electrode material, a preparation method thereof, a sodium-ion battery and an electrical device

Abstract

This application provides a sodium-ion battery cathode material and its preparation method, a sodium-ion battery, and an electrical device, relating to the field of sodium-ion batteries. The cathode material of the sodium-ion battery provided in this application includes a core and a shell, wherein the shell covers the core; the core has the chemical formula Na. a Ni x Fe y Mn z M 1‑x‑y‑z O2, where 0.9 ≤ a ≤ 1.05, 0 < x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0 < 1 - x - y - z < 1; the chemical formula of the outer shell is NaLa. r Ca 1‑r O2, where 0 < r < 1; in the core, element M includes one or more of Al, Mg, Ti, Zr, Y, La, Ca, Zn, Cu, W, Li, and B. The sodium-ion battery cathode material provided in this application can reduce residual alkali on the particle surface while suppressing side reactions with the electrolyte, thereby improving the performance stability of the cathode material.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium batteries, in particular to a sodium ion battery positive electrode material, a preparation method thereof, a sodium ion battery and an electrical equipment. BACKGROUND

[0002] At present, new energy lithium ion batteries are widely used in 3C, power batteries and energy storage markets due to their high energy density and long service life. However, with the limited abundance and difficult exploitation of lithium resources, and with the continuous consumption of lithium elements, new chemical systems are urgently needed to supplement the application market of lithium ion batteries. Sodium ion batteries are rocking chair type secondary batteries, which are consistent with the principle of lithium ion batteries. Sodium and lithium belong to the same main group elements, and both show similar "rocking chair" electrochemical charging and discharging behavior in battery operation. During charging, sodium ions are released from the cathode and embedded in the anode, and electrons pass through the external circuit. The more sodium ions embedded in the anode, the higher the charging capacity. During discharging, the opposite process occurs, and the more sodium ions return to the positive electrode, the higher the discharging capacity. In addition, the cost of lithium ion batteries is much higher than that of sodium ion batteries, so sodium ion batteries will play an equally important role in the new energy industry.

[0003] In the sodium ion battery positive electrode material, the O3 structure positive electrode material has a high initial sodium content, so the guest capacity is relatively high, but the existing O3 structure sodium ion battery positive electrode material technology still has many technical problems, such as the side reaction of sodium hydroxide and sodium carbonate on the surface of the particles with the electrolyte and the release of lattice oxygen at high voltage, which will cause the dissolution of transition metals, which will cause serious problems in the processing process and service life of the battery, so it is necessary to reduce the residual alkali on the surface of the particles and inhibit the release of lattice oxygen.

[0004] At present, the modification measures for the positive electrode material are basically around doping and coating, using doping to enhance the stability of the crystal structure, and coating to improve the interface stability. Then the lattice oxygen release of the positive electrode material is mostly located in the surface layer of the particles, and many coating agents have little effect on the stability of the surface oxygen, so the gas production is still serious, and therefore a layer of material with ion conduction and storage of oxygen ions released from the lattice is needed to be constructed on the surface to solve the problems of short cycle life and gas production of O3 structure positive electrode material. SUMMARY

[0005] The purpose of the present application is to provide a sodium ion battery positive electrode material, a preparation method thereof, a sodium ion battery and an electrical equipment to solve the above problems.

[0006] To achieve the above purpose, the following technical solutions are adopted in the present application:

[0007] The application provides a sodium ion battery positive electrode material, which comprises a core and a shell, and the shell covers the core; the chemical formula of the core is Na a Ni x Fe y Mn z M 1-x-y-z O2, wherein 0.9<=a<=1.05, 0 r Ca 1- r O2, wherein 0

[0008] Optionally, in the core, the M element comprises one or more of Al, Mg, Ti, Zr, Y, La, Ca, Zn, Cu, W, Li and B.

[0009] The application further provides a preparation method of the sodium ion battery positive electrode material, comprising the following steps:

[0010] The solutions of a nickel source, a manganese source, an iron source and an M element source are mixed, and then a pH adjuster is added, and a hydroxide precursor is obtained by using a coprecipitation method.

[0011] The hydroxide precursor is mixed with a sodium source, and then first calcination is performed, and a first calcination product is obtained after cooling.

[0012] The first calcination product is mixed with a calcium source and a lanthanum source, and then second calcination is performed, and the sodium ion battery positive electrode material is obtained.

[0013] Optionally, the nickel source comprises nickel sulfate, the manganese source comprises manganese sulfate, and the iron source comprises iron sulfate.

[0014] Optionally, the M element source comprises a sulfate of one or more of Al, Mg, Ti, Zr, Y, La, Ca, Zn, Cu, W, Li and B.

[0015] Optionally, the pH adjuster comprises at least one of ammonia and sodium hydroxide.

[0016] Optionally, the pH value of the system is adjusted to 8.0-12.0 by using the pH adjuster.

[0017] Optionally, after the hydroxide precursor is prepared, the process further comprises solid-liquid separation, washing and drying, and the temperature in the drying process is 100-300 DEG C, and the time is 2-6 h.

[0018] Optionally, the chemical formula of the hydroxide precursor is Ni x Fe y Mnz M 1-x-y-z (OH)2, wherein 0 < x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0 < 1-x-y-z < 1.0.

[0019] Optionally, the first calcination product has a chemical formula of Na a Ni x Fe y Mn z M 1-x-y-z O2, wherein 0.9 ≤ a ≤ 1.05, 0 < x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0 < 1-x-y-z < 1.0.

[0020] Optionally, the mixing ratio of the hydroxide precursor and the sodium source is a molar ratio of metal cations in the hydroxide precursor to sodium ions of 1: n, wherein 0.95 ≤ n ≤ 1.4.

[0021] Optionally, the lanthanum source comprises La2O3.

[0022] Optionally, the calcium source comprises CaCl2, CaCO3, CaO, Ca(OH), CaF2.

[0023] Optionally, the lanthanum source and the calcium source are nanoscale particles.

[0024] Optionally, the first calcination is a multi-stage calcination, and the process of the multi-stage calcination comprises: raising the temperature to 400-550°C at a temperature raising rate of 1.5-7°C / min for pre-sintering, the pre-sintering time being 4-8h; and then raising the temperature to 800-1100°C at a temperature raising rate of 1.5-7°C / min for sintering, the sintering time being 10-24h; and cooling to room temperature after the sintering.

[0025] Optionally, the calcination atmosphere of the first calcination comprises air or oxygen.

[0026] Optionally, the second calcination has a temperature of 300-600°C and a time of 5-10h. After the second calcination, the coating amount of calcium element is 300-2000ppm, and the coating amount of lanthanum element is 300-2000ppm.

[0027] The application also provides a sodium ion battery, which comprises the sodium ion battery cathode material.

[0028] The application also provides an electrical equipment, which comprises the sodium ion battery.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] The application provides a positive electrode material of a sodium ion battery, which is prepared by coating a compound containing La and Ca elements and having a perovskite structure on the surface of particles. The surface layer compound has the functions of electron / ion conduction and oxygen storage. On the one hand, the lanthanum element can adjust the crystal structure of the positive electrode material, change its physical and chemical properties, thereby improving the capacity of the battery, optimizing the crystal structure of the material, and thus improving the overall capacity of the battery. At the same time, by stabilizing the crystal structure of the positive electrode material, the lanthanum element helps to inhibit the adverse phase change during charging and discharging, thereby improving the cycle stability of the material. This is of great significance to prolong the service life of the sodium ion battery. On the other hand, the calcium element may improve the structure of the positive electrode material of the sodium ion battery through a certain mechanism, thereby improving the overall performance of the positive electrode material. Such improvement may include improving the crystallinity of the material, reducing defects, etc.; and the introduction of calcium element also helps to improve the thermal stability of the positive electrode material. Therefore, the positive electrode material of the sodium ion battery provided by the application can reduce the residual alkali on the surface of the particles while inhibiting the side reaction with the electrolyte, and improve the performance stability of the positive electrode material.

[0031] The preparation method provided by the application is simple and convenient, does not need to add an additional water washing step, reduces energy consumption, and can obtain a positive electrode material with performance advantages.

[0032] The sodium ion battery provided by the application has good energy density and cycle life, and does not produce gas during use. The electrical performance of the electrical equipment provided by the application is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation on the scope of the application.

[0034] Figure 1 SEM image of the positive electrode material of the sodium ion battery prepared in Example 1 of the application. DETAILED DESCRIPTION

[0035] As used herein:

[0036] "prepared from" is synonymous with "comprising". The terms "comprising", "including", "having" or "containing" or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, step, method, article, or apparatus.

[0037] The conjunctive word "comprise" excludes any element, step, or ingredient not specified, if used in a claim. If used in a claim, this phrase will be construed to cover a composition or process comprising, consisting of, consisting essentially of, and solid of only those materials or steps that are described. The phrase "consisting essentially of" shall mean excluding any other step, ingredient, component, or material not specified.

[0038] When expressing a value or parameter, such as a numerical value, quantity, or range of values or parameters, as a range, preferably a range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pair of an upper or preferred value and a lower or preferred value, whether or not the range is expressly disclosed, are specifically disclosed. For example, when a range "1-5" is disclosed, the described range should be interpreted to include ranges "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5", etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include the end values and all integers and fractions within the range.

[0039] In these examples, the parts and percentages described are by mass, unless otherwise indicated.

[0040] "Mass parts" refers to a basic unit of measurement that represents the mass ratio relationship of multiple components, 1 part can represent any unit mass, such as 1g, 2.689g, etc. If we say that the mass parts of component A is a parts, and the mass parts of component B is b parts, it means that the mass ratio of component A to component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that unlike mass parts, the sum of the mass parts of all components is not limited to 100 parts.

[0041] "and / or" is used to indicate that one or both of the described situations can occur, for example, A and / or B includes (A and B) and (A or B).

[0042] In order to better illustrate the technical solutions provided in the present application, before the examples, the technical solutions are stated as a whole, as follows:

[0043] In a first aspect, the present application provides a sodium ion battery positive electrode material, which comprises a core and a shell, and the shell covers the core; the chemical formula of the core is Na a Ni x Fe y Mn z M 1-x-y-zO2, wherein 0.9≤a≤1.05, 0 r Ca 1-r O2, wherein 0

[0044] wherein a can be 0.9, 0.95, 1.0, 1.05, or any value between and including 0.9 and 1.05; x can be 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.99, or any value between and including greater than 0 and less than 1.0 or any range such as 0.1-0.9, 0.2-0.9, 0.3-0.9, 0.25-0.95, 0.3-0.99, etc. y can be 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.99, or any value between and including greater than 0 and less than 1.0 or any range such as 0.1-0.9, 0.2-0.9, 0.3-0.9, 0.25-0.95, 0.3-0.99, etc. z can be 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.99, or any value between and including greater than 0 and less than 1.0 or any range such as 0.1-0.9, 0.2-0.9, 0.3-0.9, 0.25-0.95, 0.3-0.99, etc. r can be 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0.99, or any value between and including greater than 0 and less than 1.0 or any range such as 0.1-0.9, 0.2-0.9, 0.3-0.9, 0.25-0.95, 0.3-0.99, etc.

[0045] In the core, the M element includes one or more of Al, Mg, Ti, Zr, Y, La, Ca, Zn, Cu, W, Li, B.

[0046] In a second aspect, the application further provides a preparation method of a sodium ion battery cathode material, comprising:

[0047] The solution of the nickel source, the manganese source, the iron source, and the M element source is mixed with a pH adjuster, and a hydroxide precursor is obtained by using a coprecipitation method.

[0048] The hydroxide precursor is mixed with a sodium source, and then first calcination is performed to obtain a first calcination product.

[0049] The first calcination product is mixed with a calcium source and a lanthanum source, and then second calcination is performed to obtain the sodium ion battery cathode material.

[0050] In an optional embodiment, the nickel source comprises nickel sulfate, the manganese source comprises manganese sulfate, and the iron source comprises iron sulfate.

[0051] In an optional embodiment, the M element source comprises a sulfate of one or more of Al, Mg, Ti, Zr, Y, La, Ca, Zn, Cu, W, Li, and B.

[0052] In an optional embodiment, the pH adjuster comprises at least one of ammonia and sodium hydroxide.

[0053] In an optional embodiment, the pH adjuster is used to adjust the pH value of the system to 8.0-12.0.

[0054] Optionally, the pH value can be adjusted to 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, or any value between 8.0 and 12.0.

[0055] In an optional embodiment, after the hydroxide precursor is prepared, the process further comprises solid-liquid separation, washing, and drying, and the temperature in the drying process is 100-300°C, and the time is 2-6h.

[0056] Optionally, the temperature in the drying process can be 100°C, 150°C, 200°C, 250°C, 300°C, or any value between 100°C and 300°C. The drying time can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, or any value between 2h and 6h.

[0057] In an optional embodiment, the chemical formula of the hydroxide precursor is Ni x Fe y Mn z M 1-x-y-z(OH)2, wherein 0 < x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0 < 1-x-y-z < 1.0.

[0058] In an alternative embodiment, the first calcined product has a chemical formula of Na a Ni x Fe y Mn z M 1-x-y-z O2, wherein 0.9 < a < 1.05, 0 < x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0 < 1-x-y-z < 1.0.

[0059] In an alternative embodiment, the mixing ratio of the hydroxide precursor and the sodium source is a molar ratio of metal cations in the hydroxide precursor to sodium ions of 1 : n, wherein 0.95 < n < 1.4.

[0060] Alternatively, the molar ratio of metal cations in the hydroxide precursor to sodium ions can be 1 : 0.95, 1 : 1, 1 : 1.05, 1 : 1.1, 1 : 1.15, 1 : 1.2, 1 : 1.25, 1 : 1.3, 1 : 1.35, 1 : 1.4, or any value between 1 : 0.95 and 1 : 1.4.

[0061] In an alternative embodiment, the lanthanum source comprises La2O3.

[0062] In an alternative embodiment, the calcium source comprises CaCl2, CaCO3, CaO, Ca(OH), CaF2.

[0063] In an alternative embodiment, the lanthanum source and the calcium source are nanoscale particles.

[0064] In an alternative embodiment, the first calcination is a multi-stage calcination; the process of the multi-stage calcination comprises: increasing the temperature to 400-550°C at a heating rate of 1.5-7°C / min for pre-sintering, the time of the pre-sintering being 4-8h; and then increasing the temperature to 800-1100°C at a heating rate of 1.5-7°C / min for sintering, the time of the sintering being 10-24h; and cooling to room temperature after the sintering. During the multi-stage calcination, the raw materials undergo physical and chemical changes at high temperatures, making the material structure more compact. Through two-step segmented calcination, the migration distance of lithium ions during high-temperature sintering can be significantly shortened, thereby improving the compactness of the material. Moreover, through segmented calcination, the two oxides can generate single-phase lithium oxide, the crystal grains grow, and the crystallinity improves. At the same time, multi-stage calcination can remove impurities and volatile substances in the raw materials, improving the purity of the material. Ultimately, the prepared positive electrode material generally has better cycle stability.

[0065] Optionally, the temperature ramping rate during the pre-sintering can be 1.5°C / min, 2.0°C / min, 2.5°C / min, 3.0°C / min, 3.5°C / min, 4.0°C / min, 4.5°C / min, 5.0°C / min, 5.5°C / min, 6.0°C / min, 6.5°C / min, 7.0°C / min, or any value between 1.5-7°C / min; the end point temperature of the pre-sintering can be 400°C, 430°C, 460°C, 490°C, 520°C, 550°C, or any value between 400-550°C; the time of the pre-sintering can be 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, or any value between 4-8h. The temperature ramping rate during the sintering can be 1.5°C / min, 2.0°C / min, 2.5°C / min, 3.0°C / min, 3.5°C / min, 4.0°C / min, 4.5°C / min, 5.0°C / min, 5.5°C / min, 6.0°C / min, 6.5°C / min, 7.0°C / min, or any value between 1.5-7°C / min; the temperature of the sintering can be 800°C, 820°C, 840°C, 860°C, 880°C, 900°C, 920°C, 940°C, 960°C, 980°C, 1000°C, 1020°C, 1040°C, 1060°C, 1080°C, 1100°C, or any value between 800-1100°C; the time of the sintering can be 10h, 10.5h, 11h, 11.5h, 12h, 12.5h, 13h, 13.5h, 14h, 14.5h, 15h, 15.5h, 16h, 16.5h, 17h, 17.5h, 18h, 18.5h, 19h, 19.5h, 20h, 20.5h, 21h, 21.5h, 22h, 22.5h, 23h, 23.5h, 24h, or any value between 10-24h.

[0066] In an optional embodiment, the first calcination is performed in an air atmosphere.

[0067] In an optional embodiment, the second calcination is performed at a temperature of 300-600°C for 5-10h. After the second calcination, the coating amount of calcium element is 300-2000ppm, and the coating amount of lanthanum element is 300-2000ppm.

[0068] Optionally, the temperature of the second calcination can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, or any value between 300-600°C.

[0069] Optionally, the coating amount of the second calcined calcium element can be 300 ppm, 500 ppm, 700 ppm, 1000 ppm, 1200 ppm, 1400 ppm, 1600 ppm, 1800 ppm, 2000 ppm, or any value between 300-2000 ppm; the coating amount of the second calcined lanthanum element can be 300 ppm, 500 ppm, 700 ppm, 1000 ppm, 1200 ppm, 1400 ppm, 1600 ppm, 1800 ppm, 2000 ppm, or any value between 300-2000 ppm.

[0070] In a third aspect, the application further provides a sodium ion battery, raw materials of which comprise the sodium ion battery cathode material.

[0071] In a fourth aspect, the application further provides an electrical equipment, which comprises the sodium ion battery.

[0072] The embodiments of the application will be described in detail below with specific examples, but those skilled in the art will understand that the following examples are only for illustration of the application and should not be regarded as limiting the scope of the application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0073] Example 1

[0074] The present embodiment provides a sodium ion battery cathode material, and the preparation method is as follows:

[0075] (1) A mixed solution is obtained by uniformly mixing nickel sulfate, manganese sulfate, iron sulfate and aluminum sulfate solution according to the ratio of Ni:Fe:Mn:Al=40:20:35:5, and then 2 mol / L of ammonia water and sodium hydroxide solution are added to the solution to adjust the pH value of the mixed solution to 11.8, and then a hydroxide precursor Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 (OH)2 is obtained by coprecipitation, and is filtered and washed, and then dried at 200°C for 5h to obtain the dried hydroxide precursor.

[0076] (2) The dried hydroxide precursor Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05(OH)2 and sodium carbonate are weighed according to the molar ratio of metal cations in the precursor to Na ions of 1:1.05, and the above two substances are mixed uniformly, and then subjected to staged sintering in a sintering furnace: first, the temperature is increased to 400°C at a heating rate of 3°C / min for 8h of pre-sintering in an air atmosphere, and then the temperature is increased to 940°C at a heating rate of 3°C / min for 16h of sintering in an air atmosphere, and after sintering, the furnace is cooled and the positive electrode material Na 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 O2, the material is crushed by a roll crusher, 300 mesh sieved, and used.

[0077] (3) La2O3 with a particle size of 30-200nm and an addition amount of 1500ppm, and CaO with a particle size of 30-200nm and an addition amount of 216ppm are added to the Na 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 O2 material. After mixing uniformly, calcination is carried out at 450°C for 6h, and finally the sodium ion battery positive electrode material is obtained. The SEM spectrum of the positive electrode material particles is as shown in Figure 1 .

[0078] The embodiment also provides a sodium ion battery, raw materials of which include the above positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a positive electrode slurry in a ratio of 95.5%:1.5%:2%:1%, which is coated on an aluminum foil to make a positive electrode sheet, a hard carbon negative electrode material is used for a negative electrode sheet, an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed uniformly in a mass ratio of 1:1:1 under an inert atmosphere, then sodium hexafluorophosphate is dissolved in the mixed solvent to configure an electrolyte of 1mol / L; and a polyethylene film or a polyethylene film coated with ceramic is used as a separator, the remaining steps are assembled into a sodium ion battery according to a conventional method, and corresponding electrical performance tests are carried out.

[0079] Example 2

[0080] The embodiment provides a sodium ion battery positive electrode material, and a preparation method thereof is as follows:

[0081] (1) A mixed solution is obtained by uniformly mixing nickel sulfate, manganese sulfate, iron sulfate, and titanium sulfate solutions in a ratio of Ni:Fe:Mn:Ti=30:20:45:5, and then 2mol / L of ammonia water and sodium hydroxide solution are added to the solution to adjust the pH value of the mixed solution to 11.8, and then a hydroxide precursor Ni 0.3 Fe0.2 Mn 0.45 Ti 0.05 (OH)2, and filtered and washed, and then dried at 200℃ for 5h to obtain a dried hydroxide precursor.

[0082] (2) The dried hydroxide precursor Ni 0.3 Fe 0.2 Mn 0.45 Ti 0.05 (OH)2and sodium carbonate were weighed according to a molar ratio of metal cations in the precursor to Na ions of 1:1.05, and the two substances were mixed uniformly, and then were subjected to stepwise sintering in a sintering furnace: first, the temperature was increased to 400℃ at a heating rate of 3℃ / min for 8h of pre-sintering in an air atmosphere, and then the temperature was increased to 940℃ at a heating rate of 3℃ / min for sintering for 16h in an air atmosphere, and after sintering was completed, the furnace was cooled and a positive electrode material Na 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Ti 0.05 O2was obtained.

[0083] (3) La2O3 with a particle size of 30-200nm and an addition amount of 1500ppm, and CaO with a particle size of 30-200nm and an addition amount of 433ppm were added to the Na 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Ti 0.05 O2material. After being mixed uniformly, calcination was performed at 450℃ for 6h, and finally a sodium ion battery positive electrode material was obtained.

[0084] The present embodiment also provides a sodium ion battery, raw materials of which include the above positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a positive electrode slurry in a ratio of 95.5%:1.5%:2%:1%, and the positive electrode slurry is coated on an aluminum foil to make a positive electrode sheet, a hard carbon negative electrode material is used for a negative electrode sheet, an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed uniformly in a mass ratio of 1:1:1 under an inert atmosphere, and then sodium hexafluorophosphate is dissolved in the mixed solvent to configure an electrolyte of 1mol / L; and a polyethylene film or a polyethylene film coated with ceramic is used as a separator, the remaining steps are assembled into a sodium ion battery according to a conventional method, and corresponding electrical performance tests are performed.

[0085] Example 3

[0086] The present embodiment provides a sodium ion battery positive electrode material, and a preparation method thereof is as follows:

[0087] (1) The nickel sulfate, manganese sulfate, iron sulfate and aluminum sulfate and copper sulfate solution is mixed uniformly according to the ratio of Ni:Fe:Mn:Cu:Al=35:20:35:5:5 to obtain a mixed solution, and then 2 mol / L of ammonia water and sodium hydroxide solution are added to the solution to adjust the pH value of the mixed solution to 11.3, and then the hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 (OH)2 is obtained by co-precipitation, and then filtered and washed, and then dried at 200°C for 5h to obtain the dried hydroxide precursor.

[0088] (2) The dried hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 (OH)2 obtained in step (1) and sodium carbonate are weighed according to the molar ratio of metal cations in the precursor to Na ions of 1:1.05, and the above two substances are mixed uniformly, and then subjected to step-by-step sintering in a sintering furnace: first, the temperature is increased to 400°C at a heating rate of 3°C / min for 8h of pre-sintering, and the atmosphere is air atmosphere, and then the temperature is increased to 940°C at a heating rate of 3°C / min for sintering for 16h, and the atmosphere is air atmosphere, and after sintering, the furnace is cooled and the positive electrode material Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 O2 is obtained.

[0089] (3) La2O3 with a particle size of 30-200nm and an addition amount of 1500ppm, and CaO with a particle size of 30-200nm and an addition amount of 216ppm are added to the Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 O2 material. After mixing uniformly, calcine at 450°C for 6h to finally obtain a sodium ion battery positive electrode material.

[0090] The embodiment also provides a sodium ion battery, raw materials of which include the positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes in a ratio of 95.5%:1.5%:2%:1% to form a positive electrode slurry, the positive electrode slurry is coated on an aluminum foil to form a positive electrode sheet, a hard carbon negative electrode material is used as a negative electrode sheet, an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate and dimethyl carbonate are mixed in a mass ratio of 1:1:1 in an inert atmosphere, then sodium hexafluorophosphate is dissolved in the mixed solvent to form an electrolyte of 1 mol / L, a polyethylene film or a polyethylene film coated with ceramic is used as a diaphragm, and the rest of the steps are assembled into a sodium ion battery according to a conventional method, and corresponding electrical performance tests are carried out.

[0091] Embodiment 4

[0092] The embodiment provides a positive electrode material of a sodium ion battery, and a preparation method thereof.

[0093] (1) A mixed solution is obtained by uniformly mixing nickel sulfate, manganese sulfate, iron sulfate, aluminum sulfate and copper sulfate solution in a ratio of Ni:Fe:Mn:Cu:Al=35:20:35:5:5, then 2 mol / L of ammonia water and sodium hydroxide solution are added to the solution to adjust the pH value of the mixed solution to 11.4, and then a hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 (OH)2 is obtained by a coprecipitation method, and is filtered and washed, and then dried at 200°C for 5h to obtain the dried hydroxide precursor.

[0094] (2) The dried hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 (OH)2 obtained in step (1) and sodium carbonate are weighed according to a molar ratio of metal cations in the precursor to Na ions of 1:1.05, and the two substances are uniformly mixed, and then are subjected to step-by-step sintering in a sintering furnace: first, the temperature is increased to 400°C at a temperature increasing rate of 3°C / min for 8h of pre-sintering in an air atmosphere, and then the temperature is increased to 940°C at a temperature increasing rate of 3°C / min for sintering of 16h in an air atmosphere, and after sintering, the material is cooled in the furnace to obtain a positive electrode material Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 O2, the material is crushed by a roll crusher, and is sieved through a 300-mesh sieve.

[0095] (3) to Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 O2material, 30-200nm in size, 1500ppm in amount, and CaO, 30-200nm in size, 865ppm in amount, are added. After mixing, calcination is carried out at 450℃ for 6h, and finally a sodium ion battery positive electrode material is obtained.

[0096] The embodiment also provides a sodium ion battery, raw materials of which include the above positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes, to make a positive electrode slurry in a ratio of 95.5%:1.5%:2%:1%, coat the positive electrode slurry on an aluminum foil to make a positive electrode sheet, use a hard carbon negative electrode material as a negative electrode sheet, mix propylene carbonate, ethylene carbonate, and dimethyl carbonate in a mass ratio of 1:1:1 under an inert atmosphere, then dissolve sodium hexafluorophosphate in the mixed solvent to prepare an electrolyte of 1mol / L, use a polyethylene film or a polyethylene ceramic coating film as a separator, and assemble the sodium ion battery according to a conventional method and perform corresponding electrical performance tests.

[0097] Example 5

[0098] The embodiment provides a sodium ion battery positive electrode material, and a preparation method thereof is as follows:

[0099] (1) A mixed solution is obtained by uniformly mixing nickel sulfate, manganese sulfate, iron sulfate, and copper sulfate solution in a ratio of Ni:Fe:Mn:Cu:Al=35:20:35:5:5, then 2mol / L ammonia water and sodium hydroxide solution are added to the solution to adjust the pH value of the mixed solution to 11.8, and then a hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 (OH)2is obtained by a coprecipitation method, and is filtered and washed, and then dried at 200℃ for 5h to obtain the dried hydroxide precursor.

[0100] (2) The dried hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05(Ni0.5Co0.2Mn0.3) (OH) 2 and sodium carbonate are weighed according to the molar ratio of metal cations in the precursor to Na ions of 1:1.05, and the above two substances are mixed uniformly, and then subjected to step sintering in a sintering furnace: first, the temperature is increased to 400°C at a heating rate of 3°C / min for 8h of pre-sintering in an air atmosphere, and then the temperature is increased to 940°C at a heating rate of 3°C / min for 16h of sintering in an air atmosphere, and after sintering, the furnace is cooled and the positive electrode material Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 O2, the material is crushed by a roll crusher, 300 mesh sieved, and ready for use.

[0101] (3) La2O3 with a particle size of 30-200nm and an addition amount of 800ppm, and CaO with a particle size of 30-200nm and an addition amount of 865ppm are added to the Ni 0.35 Fe 0.2 Mn 0.35 Cu 0.05 Al 0.05 O2 material. After mixing uniformly, calcining at 450°C for 6h, the sodium ion battery positive electrode material is finally obtained.

[0102] The present embodiment also provides a sodium ion battery, the raw materials of which include the above positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes in a ratio of 95.5%:1.5%:2%:1% to make a positive electrode slurry, which is coated on an aluminum foil to make a positive electrode sheet, and a hard carbon negative electrode material is used for the negative electrode sheet. The electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed uniformly in a mass ratio of 1:1:1 under an inert atmosphere, and then sodium hexafluorophosphate is dissolved in the mixed solvent to prepare an electrolyte of 1mol / L. A polyethylene film or a polyethylene film coated with ceramic is used as a separator, and the remaining steps are assembled into a sodium ion battery according to a conventional method, and corresponding electrical performance tests are carried out.

[0103] Example 6

[0104] The present embodiment provides a sodium ion battery positive electrode material, and the preparation method is as follows:

[0105] (1) A mixed solution is obtained by uniformly mixing nickel sulfate, manganese sulfate, iron sulfate, and zinc sulfate solutions in a ratio of Ni:Fe:Mn:Cu:Zn=35:20:35:10, and then 2mol / L of ammonia water and sodium hydroxide solution are added to the solution to adjust the pH value of the mixed solution to 11.8, and then a hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Zn0.1 (OH)2, and filtered and washed, and then dried at 200°C for 5h to obtain a dried hydroxide precursor.

[0106] (2) The dried hydroxide precursor Ni 0.35 Fe 0.2 Mn 0.35 Zn 0.1 (OH)2and sodium carbonate were weighed according to a molar ratio of metal cations in the precursor to Na ions of 1:1.05, and the two substances were mixed uniformly, and then were subjected to stepwise sintering in a sintering furnace: first, the temperature was increased to 400°C at a rate of 3°C / min for 8h of pre-sintering in an air atmosphere, and then the temperature was increased to 940°C at a rate of 3°C / min for 16h of sintering in an air atmosphere, and after sintering, the furnace was cooled to obtain a positive electrode material Ni 0.35 Fe 0.2 Mn 0.35 Zn 0.1 O2, the material was crushed by a roll crusher, and sieved to 300 mesh, and was ready for use.

[0107] (3) La2O3 with a particle size of 30-200nm and an addition amount of 1500ppm, and CaO with a particle size of 30-200nm and an addition amount of 865ppm were added to Ni 0.35 Fe 0.2 Mn 0.35 Zn 0.1 O2, and after uniform mixing, calcination was performed at 450°C for 6h to finally obtain a sodium ion battery positive electrode material.

[0108] The example also provides a sodium ion battery, raw materials of which include the above positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a positive electrode slurry in a ratio of 95.5%:1.5%:2%:1%, and the positive electrode slurry is coated on an aluminum foil to make a positive electrode sheet, a hard carbon negative electrode material is used for a negative electrode sheet, an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed uniformly in a mass ratio of 1:1:1 under an inert atmosphere, and then sodium hexafluorophosphate is dissolved in the mixed solvent to configure an electrolyte of 1 mol / L; and a polyethylene film or a polyethylene film coated with ceramic is used as a separator, the remaining steps are assembled into a sodium ion battery according to a conventional method, and corresponding electrical performance tests are performed.

[0109] Example 7

[0110] The example provides a sodium ion battery positive electrode material, and a preparation method thereof is as follows:

[0111] Different from example 6, the sintering temperature in step (2) is increased to 980℃, and other parameters remain unchanged, to finally obtain the sodium-ion battery cathode material.

[0112] The present embodiment also provides a sodium-ion battery, raw materials of which include the above-mentioned cathode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a cathode slurry in a ratio of 95.5%:1.5%:2%:1%, coat the cathode slurry on an aluminum foil to make a cathode sheet, use a hard carbon negative material as a negative electrode sheet, mix propylene carbonate, ethylene carbonate, and dimethyl carbonate in a mass ratio of 1:1:1 under an inert atmosphere, then dissolve sodium hexafluorophosphate in the mixed solvent to configure an electrolyte of 1 mol / L, use a polyethylene film or a polyethylene ceramic coating film as a separator, and assemble the sodium-ion battery according to a conventional method and perform corresponding electrical performance tests.

[0113] Example 8

[0114] The present embodiment provides a sodium-ion battery cathode material, a preparation method of which is as follows:

[0115] Different from example 6, the sintering temperature in step (2) is increased to 980℃, and other parameters remain unchanged, to finally obtain the sodium-ion battery cathode material. 0.35 Fe 0.2 Mn 0.35 Zn 0.1 O2 material, and the particle size of La2O3 is 30-200 nm, and the addition amount is 1500 ppm, and the particle size of CaO is 30-200 nm, and the addition amount is 865 ppm. After mixing uniformly, calcination is performed at 530℃ for 6h. Other parameters remain unchanged, to finally obtain the sodium-ion battery cathode material.

[0116] The present embodiment also provides a sodium-ion battery, raw materials of which include the above-mentioned cathode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a cathode slurry in a ratio of 95.5%:1.5%:2%:1%, coat the cathode slurry on an aluminum foil to make a cathode sheet, use a hard carbon negative material as a negative electrode sheet, use a hard carbon negative material as a negative electrode sheet, mix propylene carbonate, ethylene carbonate, and dimethyl carbonate in a mass ratio of 1:1:1 under an inert atmosphere, then dissolve sodium hexafluorophosphate in the mixed solvent to configure an electrolyte of 1 mol / L, use a polyethylene film or a polyethylene ceramic coating film as a separator, and assemble the sodium-ion battery according to a conventional method and perform corresponding electrical performance tests.

[0117] Example 9

[0118] The present embodiment provides a sodium-ion battery cathode material, a preparation method of which is as follows:

[0119] Different from Example 1, the molar ratio of metal cation to Na ion in step (2) is changed to 1:1.0; other parameters remain unchanged, and finally a sodium ion battery cathode material is obtained.

[0120] The present embodiment also provides a sodium ion battery, raw materials of which include the above-mentioned cathode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a cathode slurry in a ratio of 95.5%:1.5%:2%:1%, coat the cathode slurry on an aluminum foil to make a cathode sheet, use a hard carbon negative material as a negative electrode sheet, mix propylene carbonate, ethylene carbonate and dimethyl carbonate in a mass ratio of 1:1:1 under an inert atmosphere, then dissolve sodium hexafluorophosphate in the mixed solvent to prepare an electrolyte of 1 mol / L, and use a polyethylene film or a polyethylene film coated with ceramic as a separator. The rest of the steps are assembled into a sodium ion battery according to a conventional method, and corresponding electrical performance tests are carried out.

[0121] Comparative Example 1

[0122] The present comparative example provides a sodium ion battery cathode material, and the preparation method is as follows:

[0123] (1) A mixed solution is obtained by uniformly mixing nickel sulfate, manganese sulfate, iron sulfate and aluminum sulfate solutions in a ratio of Ni:Fe:Mn:Al = 40:20:35:5, then 2 mol / L of ammonia water and sodium hydroxide solution are added to the solution to adjust the pH value of the mixed solution to 11.8, and then a hydroxide precursor Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 (OH)2 is obtained by a coprecipitation method, and is filtered and washed, and then dried at 200°C for 5h to obtain dried hydroxide precursor.

[0124] (2) The dried hydroxide precursor Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 (OH)2 obtained in step (1) and sodium carbonate are weighed according to a molar ratio of metal cation to Na ion in the precursor of 1:1.05, and the two substances are uniformly mixed, and then are subjected to step-by-step sintering in a sintering furnace: first, the temperature is increased to 400°C at a heating rate of 3°C / min for 8h of pre-sintering in an air atmosphere, and then the temperature is increased to 940°C at a heating rate of 3°C / min for 16h of sintering in an air atmosphere. After sintering, the furnace is cooled down and a cathode material Na 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05O2, the material is crushed by a roll crusher, sieved to 300 mesh, and a sodium ion battery positive electrode material is obtained.

[0125] The comparative example also provides a sodium ion battery, raw materials of the sodium ion battery including the above positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a positive electrode slurry in a ratio of 95.5%:1.5%:2%:1%, the positive electrode slurry is coated on an aluminum foil to form a positive electrode sheet, a hard carbon negative electrode material is used as a negative electrode sheet, an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed in a mass ratio of 1:1:1 under an inert atmosphere, then sodium hexafluorophosphate is dissolved in the mixed solvent to configure an electrolyte of 1 mol / L, a polyethylene film or a polyethylene ceramic coating film is used as a separator, and the remaining steps are assembled into the sodium ion battery according to a conventional method, and corresponding electrical performance tests are performed.

[0126] Comparative Example 2

[0127] The comparative example provides a sodium ion battery positive electrode material, and a preparation method is as follows:

[0128] In the comparative example, parameters in steps (1) and (2) are the same as those in the example 1, and different from the example 1 is that: in step (3), 1000 ppm of nano-Al2O3 particles are added to the Na 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 O2 material, the sodium ion battery positive electrode material is obtained by uniformly mixing and sintering at 450 DEG C for 6 h.

[0129] The comparative example also provides a sodium ion battery, raw materials of the sodium ion battery including the above positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes to make a positive electrode slurry in a ratio of 95.5%:1.5%:2%:1%, the positive electrode slurry is coated on an aluminum foil to form a positive electrode sheet, a hard carbon negative electrode material is used as a negative electrode sheet, an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed in a mass ratio of 1:1:1 under an inert atmosphere, then sodium hexafluorophosphate is dissolved in the mixed solvent to configure an electrolyte of 1 mol / L, a polyethylene film or a polyethylene ceramic coating film is used as a separator, and the remaining steps are assembled into the sodium ion battery according to a conventional method, and corresponding electrical performance tests are performed.

[0130] Comparative Example 3

[0131] The comparative example provides a sodium ion battery positive electrode material, and a preparation method is as follows:

[0132] In the comparative example, parameters in steps (1) and (2) are the same as those in the example 1, and different from the example 1 is that: in step (3), 1000 ppm of nano-Al2O3 particles are added to the Na 1.01 Ni0.4 Fe 0.2 Mn 0.35 Al 0.05 O2 material, 1000 ppm of nano-Al2O3 particles and 500 ppm of MgO are added, uniformly mixed, and sintered at 450°C for 6h to obtain a sodium-ion battery positive electrode material.

[0133] The sodium-ion battery provided by the comparative example also includes the above-mentioned positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes in a ratio of 95.5%:1.5%:2%:1% to form a positive electrode slurry, is coated on an aluminum foil to form a positive electrode sheet; a hard carbon negative electrode material is used for the negative electrode sheet; an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed in a mass ratio of 1:1:1 under an inert atmosphere, sodium hexafluorophosphate is then dissolved in the mixed solvent to prepare an electrolyte with a concentration of 1 mol / L; a polyethylene film or a polyethylene ceramic coating film is used as a separator, and the remaining steps are assembled into a sodium-ion battery according to a conventional method, and corresponding electrical performance tests are performed.

[0134] Comparative Example 4

[0135] The sodium-ion battery positive electrode material provided by the comparative example is prepared according to the following method:

[0136] In the comparative example, the parameters in steps (1) and (2) are the same as those in Example 1, and the difference from Example 1 is that, in step (3), 800 ppm of nano-Al2O3 particles and 700 ppm of MgO are added to the Na 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 O2 material, 1000 ppm of nano-Al2O3 particles and 500 ppm of MgO are added, uniformly mixed, and sintered at 450°C for 6h to obtain a sodium-ion battery positive electrode material.

[0137] The sodium-ion battery provided by the comparative example also includes the above-mentioned positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes in a ratio of 95.5%:1.5%:2%:1% to form a positive electrode slurry, is coated on an aluminum foil to form a positive electrode sheet; a hard carbon negative electrode material is used for the negative electrode sheet; an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed in a mass ratio of 1:1:1 under an inert atmosphere, sodium hexafluorophosphate is then dissolved in the mixed solvent to prepare an electrolyte with a concentration of 1 mol / L; a polyethylene film or a polyethylene ceramic coating film is used as a separator, and the remaining steps are assembled into a sodium-ion battery according to a conventional method, and corresponding electrical performance tests are performed.

[0138] Comparative Example 5

[0139] The comparative example provides a sodium ion battery positive electrode material, and the preparation method is as follows:

[0140] The parameters in step (1) and step (2) in the comparative example are the same as those in example 1, and the difference from example 1 is that: in step (3), 1000 ppm of nano-Al2O3 particles and 500 ppm of MgO and 400 ppm of ZrO are added to the O2 material, and the mixture is sintered at 450℃ for 6h to obtain a sodium ion battery positive electrode material. 1.01 Ni 0.4 Fe 0.2 Mn 0.35 Al 0.05 O2 material, and the mixture is sintered at 450℃ for 6h to obtain a sodium ion battery positive electrode material.

[0141] The comparative example also provides a sodium ion battery, which is prepared from the above-mentioned positive electrode material, a binder, a polyacrylonitrile copolymer, and carbon nanotubes in a ratio of 95.5%:1.5%:2%:1% to form a positive electrode slurry, which is coated on an aluminum foil to form a positive electrode sheet; a hard carbon negative electrode material is used for the negative electrode sheet; an electrolyte includes an organic solvent and a sodium salt, propylene carbonate, ethylene carbonate, and dimethyl carbonate are mixed in a mass ratio of 1:1:1 under an inert atmosphere, and then sodium hexafluorophosphate is dissolved in the mixed solvent to prepare an electrolyte of 1mol / L; and a polyethylene film or a polyethylene film coated with ceramic is used as a separator, and the remaining steps are assembled into a sodium ion battery according to a conventional method, and corresponding electrical performance tests are performed.

[0142] The electrical performance of the batteries prepared in examples 1-9 and comparative examples 1-5 is tested, as shown in Table 1:

[0143] Table 1 Electrical performance of sodium ion batteries prepared in examples and comparative examples

[0144]

[0145] It can be seen that in examples 1-9 of the present application, the prepared sodium ion battery positive electrode material is coated with lanthanum and / or calcium. In comparative examples 1-5, comparative example 1 is a sodium ion battery prepared from a positive electrode material without coating, comparative example 2 is a sodium ion battery prepared from a positive electrode material coated with aluminum, comparative example 3 is a sodium ion battery prepared from a positive electrode material coated with aluminum and magnesium, comparative example 4 is a sodium ion battery prepared from a positive electrode material coated with aluminum and magnesium, and comparative example 5 is a sodium ion battery prepared from a positive electrode material coated with aluminum, magnesium, and zirconium.

[0146] On one hand, from Table 1, it can be seen that in Examples 1-9, the residual alkali amount on the surface of the positive electrode material is lower than that of Comparative Examples 1-5 when coated with lanthanum and / or calcium, which means that the positive electrode material is not prone to react with the electrolyte, thereby avoiding irreversible degradation of the crystal structure of the positive electrode material. Reducing the amount of residual alkali on the surface can reduce these harmful interfacial reactions, thereby maintaining the structural stability of the positive electrode material. This can also be reflected in the 200 cycles in Table 1. In Examples 1-9, the lowest cycle efficiency is Example 4, which is 96.5%, and the highest cycle efficiency is Example 1, which is 98.1%. In Comparative Examples 1-5, the highest cycle efficiency is Comparative Example 5, which is 87.4. It can be seen that the lowest value of the 200 cycle efficiency when using the technical solution of the present application is still 9.1% higher than the best existing technology Comparative Example 5. Therefore, the present application can significantly improve the cycle efficiency of sodium-ion batteries after coating with lanthanum and / or calcium.

[0147] On the other hand, the lowest thickness change rate during the cycle process in Examples 1-9 is Example 9, which is 1.2%, and the highest is Example 1 and Example 8, which is 2.6%. In Comparative Examples 1-5, the thickness change during the cycle process is all above 4.4%. This is because after coating with lanthanum and / or calcium, the residual alkali amount on the surface of the positive electrode material is reduced, thereby reducing the side reaction between the positive electrode material and the electrolyte, and thus greatly reducing the thickness change rate during the cycle process.

[0148] Therefore, by the interface design of La and / or Ca composite coating, the structural stability of the positive electrode material is significantly improved, and the cycle capacity retention rate is significantly improved compared with the comparative examples.

[0149] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit them. Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solution to deviate from the scope of the technical solutions of the embodiments of the present application.

[0150] Furthermore, to the extent that the terms "comprises", "comprising", "includes", "including" and "has" or any variation thereof are used in the following description and / or claims, such terms are intended to include a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Also, where appropriate to context, the above description and / or claims can refer to actions to be taken by a person or apparatus. Such actions are sometimes referred to as being taken by an "operator" or "user" where it is contextualually appropriate. However, such actions, or steps, are taken autonomously and automatically by an apparatus, without intervention of a person.

Claims

1. A method for preparing a sodium-ion battery cathode material, characterized in that, The sodium-ion battery cathode material comprises a core and a shell, wherein the shell covers the core; the core has the chemical formula Na. a Ni x Fe y Mn z M 1-x-y-z O2, where 0.9 ≤ a ≤ 1.05, 0 < x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0 < 1 - xyz < 1; the chemical formula of the outer shell is NaLa. r Ca 1-r O2, where 0 < r < 1; In the kernel, element M includes one or more of Al, Mg, Ti, Zr, Y, La, Ca, Zn, Cu, W, Li, and B; The method for preparing the sodium-ion battery cathode material includes: Solutions of nickel, manganese, iron and M elements were mixed and a pH adjuster was added. The hydroxide precursor was obtained by co-precipitation. The hydroxide precursor was mixed with a sodium source and then subjected to a first calcination, followed by cooling to obtain a first calcined product. The first calcined product is mixed with a calcium source and a lanthanum source and then subjected to a second calcination to obtain the sodium-ion battery cathode material.

2. The method for preparing the sodium-ion battery cathode material according to claim 1, characterized in that, At least one of the following conditions must be met: a. The nickel source includes nickel sulfate, the manganese source includes manganese sulfate, and the iron source includes ferric sulfate; b. The source of element M includes one or more sulfates of Al, Mg, Ti, Zr, Y, La, Ca, Zn, Cu, W, Li, and B; c. The pH adjuster includes at least one of ammonia and sodium hydroxide; d. Adjust the pH of the system to 8.0-12.0 using the pH adjuster described above; e. After obtaining the hydroxide precursor, the process further includes solid-liquid separation, washing, and drying. The drying process is carried out at a temperature of 100-300℃ for 2-6 hours.

3. The method for preparing the sodium-ion battery cathode material according to claim 1, characterized in that, At least one of the following conditions must be met: f. The chemical formula of the hydroxide precursor is Ni x Fe y Mn z M 1-x-y-z (OH)2, where 0 < x < 1.0, 0 < y < 1.0, 0 < z < 1.0, 0 < 1-xyz < 1.0; g. The chemical formula of the first calcined product is Na. a Ni x Fe y Mn z M 1-x-y-z O2, where 0.9≤a≤1.05, 0<x<1.0, 0<y<1.0, 0<z<1.0, 0<1-xyz<1.

0.

4. The method for preparing the sodium-ion battery cathode material according to claim 3, characterized in that, At least one of the following conditions must be met: h. The mixing ratio of the hydroxide precursor to the sodium source is a molar ratio of metal cations to sodium ions in the hydroxide precursor of 1:n, where 0.95≤n≤1.4; i. The lanthanum source includes La2O3; j. The calcium source includes CaCl2, CaCO3, CaO, Ca(OH)2, and CaF2; k. The lanthanum source and the calcium source are nano-sized particles.

5. The method for preparing the sodium-ion battery cathode material according to claim 1, characterized in that, At least one of the following conditions must be met:

1. The first calcination is a multi-stage calcination; m. The calcination atmosphere of the first calcination includes air and oxygen; n. The second calcination temperature is 300-600℃, and the time is 5-10h.

6. The method for preparing the sodium-ion battery cathode material according to claim 5, characterized in that, The multi-stage calcination process includes: raising the temperature to 400-550℃ at a heating rate of 1.5-7℃ / min for pre-sintering, the pre-sintering time being 4-8h; then raising the temperature to 800-1100℃ at a heating rate of 1.5-7℃ / min for sintering, the sintering time being 10-24h; and cooling to room temperature after sintering.

7. The method for preparing the sodium-ion battery cathode material according to claim 1, characterized in that, After the second calcination, the calcium coating amount is 300-2000 ppm, and the lanthanum coating amount is 300-2000 ppm.

8. A sodium-ion battery, characterized in that, The raw materials include sodium-ion battery cathode materials prepared by the preparation method described in any one of claims 1-7.

9. An electrical-related device, characterized in that, Including the sodium-ion battery as described in claim 8.

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