Sodium ion battery positive electrode material precursor, preparation method therefor and use thereof

Abstract

A sodium ion battery positive electrode material precursor, a preparation method therefor and a use thereof. The sodium ion battery positive electrode material precursor comprises a positive electrode material precursor and a NASICON-type material precursor, wherein the NASICON-type material precursor is a substance which is converted into a NASICON-type material after calcination. The NASICON-type material precursor and the positive electrode material precursor are used in conjunction, thereby effectively improving the sodium ion migration efficiency and sodium storage performance. The NASICON-type material is preferably coated on the surface of a positive electrode material, thereby improving the uniformity of a coating layer, and thus greatly improving the cycle performance and the rate capability of the material. Moreover, a common positive electrode material precursor and a NASICON-type material precursor are used in conjunction at a precursor end, thereby overcoming the defect of poor air and water stability of coating of the positive electrode material in the subsequent sintering stage, reducing the complexity of the subsequent process, and reducing the production cost.

Description

Sodium ion battery positive electrode material precursor and its preparation method and application Technical Field

[0001] The present application belongs to the technical field of sodium ion batteries and relates to a sodium ion battery positive electrode material precursor and a preparation method and application thereof. Background Art

[0002] Lithium, sodium, and potassium all belong to the alkali metal group IA of the periodic table and share similar physical and chemical properties. In theory, they can all serve as metal ion carriers in secondary batteries. Lithium, with its smaller ionic radius, higher standard potential, and significantly higher specific capacity than sodium and potassium, has been used earlier and more widely in secondary batteries. However, global lithium reserves are limited, and with the significant increase in demand for batteries for the development of new energy vehicles, resource bottlenecks are emerging, and high costs are limiting the large-scale application of lithium-ion batteries.

[0003] Sodium resources are extremely abundant, with an abundance of 2.64% in the Earth's crust, 440 times that of lithium. Sodium resources are widely distributed and simple to extract. Sodium's emergence as a lithium alternative is garnering increasing attention in the battery field. Recent developments have yielded remarkable results in both comprehensive performance and demonstration applications of sodium-ion batteries. As a beneficial complement to lithium-ion batteries, sodium-ion batteries are poised for significant development in large-scale energy storage and micro-electric vehicles. High-energy-density electrode materials remain a highly sought-after goal.

[0004] The key technology for sodium-ion batteries lies primarily in materials. The key to achieving long-life batteries lies in developing highly stable materials. Due to differences in ionic properties, simply replacing the lithium in lithium-ion battery electrode materials with sodium is not suitable. Therefore, finding electrode materials suitable for sodium-ion batteries is crucial for the practical application of lithium-ion batteries.

[0005] In the past decade, as one of the key components of sodium ion batteries, cathode materials have been widely studied, such as layered oxides, polyanion compounds, Prussian blue compounds, organic compounds, etc. x TMO2 (TM, typically a transition metal, with x ≤ 1) is similar to the commercially successful lithium-ion layered oxides and has been extensively studied for its advantages, including high specific capacity, simple preparation, high compaction density, and adjustable voltage range. However, sodium-ion layered oxide cathode materials face complex structural evolution when achieving reversible sodium ion extraction and insertion, which seriously affects their capacity retention during long cycling.

[0006] Although doping or substitution of transition metal sites can significantly inhibit phase transition, inhibit the migration of transition metal ions and improve the chemical and electrochemical stability of desodiumated materials, it will inevitably reduce the content of redox couples in the system and thus affect the energy density of the system. In addition, too little doping ion content will not be enough to stabilize the structure of the layered oxide material. In addition, K can be doped into the sodium ion site to + Mg 2+ , Ca 2+ or Zn 2+ , playing a supporting role, thereby effectively alleviating the electrostatic repulsion between the sodium layers OO and inhibiting the occurrence of phase transition, but the doping amount is difficult to increase, and it will also sacrifice the energy density of the system.

[0007] While coating modification has been widely used and proven effective in lithium-ion layered oxide cathode materials, research on sodium-ion layered oxides is relatively limited. This is primarily due to the poor air and water stability of sodium-ion layered oxides, making the aqueous coating method commonly used in lithium batteries unsuitable for sodium-ion batteries. Furthermore, the complex process significantly increases the cost of preparing the electrode materials.

[0008] Therefore, it is imperative to develop a simple and effective coating method that can improve the cycling performance of sodium-ion layered oxide materials at higher specific capacities.

[0009] Summary of the Invention

[0010] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0011] In view of the above problems existing in the prior art, the purpose of this application is to provide a sodium ion battery positive electrode material precursor and its preparation method and application.

[0012] To achieve the above objectives, this application adopts the following technical solutions:

[0013] In a first aspect, the present application provides a sodium ion battery cathode material precursor, wherein the sodium ion battery cathode material precursor comprises a cathode material precursor and a NASICON type material precursor;

[0014] The NASICON type material precursor is a substance that is converted into a NASICON type material after calcination.

[0015] It should be noted that, in the "calcination" process of the "NASICON-type material precursor is a substance that is converted into a NASICON-type material after calcination", sodium needs to be added before sintering. For example, the NASICON-type material precursor is mixed with sodium salt and then calcined to obtain a NASICON-type material.

[0016] In the present application, there is no limitation on the existence form of the positive electrode material precursor and the NASICON type material precursor. The two can exist in the form of a mixture or in a coated state. For example, the NASICON type material precursor is coated on the surface of the positive electrode material precursor to form the sodium ion battery positive electrode material precursor.

[0017] NASICON-type materials have a conductivity far higher than that of lithium ions, and the NASICON structure is flexible and can accommodate transition metal ions, which can introduce electronic conductivity and store sodium ions, effectively improving the efficiency of sodium ion migration. It is further optional to coat the NASICON-type material on the surface of the positive electrode material to improve the uniformity of the coating layer, thereby greatly improving the cycle performance and rate performance of the material. At the same time, this application solves the problem of poor air and water stability of the coating in the sintering stage of the rear-end positive electrode material by combining an ordinary positive electrode material precursor with a NASICON-type material precursor at the precursor end.

[0018] The use of the sodium ion battery positive electrode material precursor described in this application to prepare the sodium ion battery positive electrode material can effectively improve the cycle stability and rate performance of the sodium ion battery while having the advantage of low cost.

[0019] As an optional solution, a NASICON-type material precursor is coated on the surface of the positive electrode material precursor to form the sodium ion battery positive electrode material precursor. In the positive electrode material prepared using the sodium ion battery positive electrode material precursor, the surface of the sodium battery positive electrode material is coated with a layer of NASICON-type material, which can better improve the sodium ion migration efficiency.

[0020] The following are optional technical solutions for this application, but are not intended to limit the technical solutions provided in this application. Through the following preferred technical solutions, the technical objectives and beneficial effects of this application can be better achieved and realized.

[0021] In one embodiment, the cathode material precursor is a layered oxide cathode material precursor, which may be a quaternary layered oxide cathode material precursor.

[0022] In one embodiment, the chemical formula of the quaternary layered oxide positive electrode material is Ni a Fe b Cu c Mn d(OH)2, where 0 < a ≤ 0.4, 0 < b ≤ 0.4, 0 < c ≤ 0.3, 0 < d ≤ 0.6, and a + b + c + d = 1. Exemplarily, a can be 0.001, 0.005, 0.01, 0.02, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4, etc.; b can be 0.001, 0.005, 0.01, 0.02, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4, etc.; c can be 0.001, 0.005, 0.01, 0.02, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25 or 0.3, etc.; d can be 0.001, 0.005, 0.01, 0.02, 0.05, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55 or 0.6, etc. This quaternary layered oxide cathode material is simply referred to as a nickel-iron-copper-manganese quaternary precursor.

[0023] Due to the poor air and water stability of the layered oxide sodium-ion cathode material, the process of sintering and coating in the cathode stage is extremely complex. In this application, coating is carried out at the precursor stage, which can reduce the complexity of subsequent processes and lower production costs.

[0024] In one embodiment, the NASICON-type material is NaMg x Zr y Ti 1-x-y (PO4)3, where 0.1 ≤ x ≤ 0.3, 0.1 ≤ y ≤ 0.3. x can be, for example, 0.1, 0.15, 0.2, 0.25 or 0.3, etc.; y can be, for example, 0.1, 0.15, 0.2, 0.25 or 0.3, etc.

[0025] In a second aspect, this application provides a method for preparing a precursor of a sodium-ion battery cathode material as described in the first aspect, and the method includes the following steps:

[0026] (1) Prepare the raw materials of the NASICON-type material precursor into aqueous solutions respectively, and add them to the reaction system containing the cathode material precursor in a co-current manner with an ammonia aqueous solution for reaction to obtain the precursor of the sodium-ion battery cathode material.

[0027] This application uses a wet coating method to uniformly coat a layer of a precursor with a NASICON structure on the surface of a positive electrode material precursor (such as a nickel-iron-copper-manganese quaternary precursor). The precursor is used to prepare a positive electrode material. After a one-step sintering process, a NASICON-type material-coated sodium ion battery positive electrode material can be obtained. NASICON-type materials have a stable structural skeleton, high electronic conductivity and good thermal stability, which can effectively improve the efficiency of sodium ion migration, thereby improving the electrochemical performance of sodium ion battery positive electrode materials.

[0028] As an optional technical solution for the preparation method of the sodium ion battery positive electrode material precursor described in the present application, the raw materials of the NASICON type material precursor include phosphoric acid, magnesium salt, zirconium salt and titanium salt.

[0029] The present application does not limit the specific types of magnesium salts, zirconium salts and titanium salts. By way of example and not limitation, the magnesium salt may be magnesium sulfate, the zirconium salt may be zirconium sulfate, and the titanium salt may be titanyl sulfate.

[0030] In one embodiment, the concentration of the aqueous solution in step (1) is independently 0.1 mol / L to 1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.8 mol / L or 1 mol / L.

[0031] In one embodiment, the feed rate of the aqueous solution prepared with phosphoric acid is 30 L / h to 90 L / h, for example, 30 L / h, 35 L / h, 38 L / h, 40 L / h, 43 L / h, 46 L / h, 48 L / h, 50 L / h, 55 L / h, 60 L / h, 65 L / h, 70 L / h, 75 L / h, 80 L / h, 85 L / h or 90 L / h, etc.

[0032] In one embodiment, the feed rate of the aqueous solution prepared with magnesium salt is 10 L / h to 30 L / h, for example, 10 L / h, 15 L / h, 18 L / h, 20 L / h, 23 L / h, 26 L / h, 28 L / h or 30 L / h.

[0033] In one embodiment, the feed rate of the aqueous solution prepared with zirconium salt is 10L / h to 30L / h, for example, 10L / h, 15L / h, 18L / h, 20L / h, 23L / h, 26L / h, 28L / h or 30L / h.

[0034] In one embodiment, the feed rate of the aqueous solution prepared with titanium salt is 50 L / h to 200 L / h, for example, 50 L / h, 80 L / h, 100 L / h, 120 L / h, 140 L / h, 160 L / h, 180 L / h or 200 L / h.

[0035] In one embodiment, the mass concentration of the aqueous ammonia solution is 15% to 30%, such as 15%, 16%, 18%, 20%, 22%, 23%, 25%, 27%, 28% or 30%, etc.

[0036] In one embodiment, the feeding rate of the aqueous ammonia solution is 5 L / h to 30 L / h, such as 5 L / h, 10 L / h, 15 L / h, 18 L / h, 20 L / h, 23 L / h, 26 L / h, 28 L / h or 30 L / h, etc.

[0037] In one embodiment, the time for co-current addition is 1 h to 15 h, such as 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h or 15 h, etc.

[0038] In one embodiment, the cathode material precursor is a layered oxide cathode material, and may be a quaternary layered oxide cathode material.

[0039] Since the air and water stability of the layered oxide sodium-ion cathode material is poor, the process of sintering and coating in the cathode stage is extremely complex. In this application, wet coating is carried out at the precursor end, which can greatly improve the uniformity of the coating layer, reduce the complexity of the subsequent process, and reduce the production cost.

[0040] In one embodiment, the reaction system containing the cathode material precursor is: the reaction system for co-precipitating the cathode material precursor.

[0041] This application does not specifically limit the preparation method of the cathode material precursor, and those skilled in the art can refer to the methods disclosed in the prior art for preparation.

[0042] Taking the quaternary layered oxide cathode material with the cathode material precursor having the chemical formula Ni a Fe b Cu c Mn d (OH)2 (where 0 < a ≤ 0.4, 0 < b ≤ 0.4, 0 < c ≤ 0.3, 0 < d ≤ 0.6, and a + b + c + d = 1) as an example, an exemplary preparation method of a sodium-ion battery cathode material precursor is provided, including the following steps:

[0043] Step 1: Prepare a nickel-iron-copper-manganese metal salt solution A with a total metal ion concentration of 0.5 mol / L to 2.5 mol / L by mixing soluble nickel salt, soluble iron salt, soluble copper salt and soluble manganese salt in a certain proportion;

[0044] Prepare a complexing agent solution B with a concentration of 0.05 mol / L to 0.1 mol / L;

[0045] Industrial liquid alkali is used as precipitant C;

[0046] Step 2: Add a certain amount of pure water to the reactor, add liquid alkali and a complexing agent to prepare a bottom liquid, continuously introduce nitrogen for protection, add the mixed solution A, the complexing agent solution B, and the precipitant C to the reactor at a certain flow rate, react at 30°C to 60°C, maintain the reaction pH at 8.5 to 12, the complexing agent concentration at 0.01mol / L to 0.1mol / L, and the stirring speed at 200rpm to 500rpm. After a period of reaction, suspend feeding to obtain a nickel-iron-manganese-copper hydroxide precursor;

[0047] Step 3: Phosphoric acid, magnesium salt, zirconium salt, and titanium salt are respectively prepared into aqueous solutions of a certain concentration, and are fed simultaneously with an ammonia solution at a certain flow rate for a period of time to obtain a coated sodium ion battery positive electrode material precursor.

[0048] In one embodiment, in step 1, the soluble nickel salt includes but is not limited to at least one of nickel sulfate, nickel chloride and nickel nitrate.

[0049] In one embodiment, in step 1, the soluble iron salt includes but is not limited to at least one of ferrous sulfate, ferrous chloride and ferrous nitrate.

[0050] In one embodiment, in step 1, the soluble copper salt includes but is not limited to at least one of copper sulfate, copper chloride and copper nitrate.

[0051] In one embodiment, in step 1, the soluble manganese salt includes but is not limited to at least one of manganese sulfate, manganese chloride and manganese nitrate.

[0052] In one embodiment, in step 1, the complexing agent in the complexing agent solution B is selected from at least one of ammonia water, EDTA, ammonium bicarbonate and sodium pyrophosphate.

[0053] In one embodiment, in step 1, the mass concentration of industrial liquid caustic soda is 32%.

[0054] In one embodiment, in step 2, the volume of the reactor is 8000L.

[0055] In a third aspect, the present application provides a sodium ion battery positive electrode material, which is prepared using the sodium ion battery positive electrode material precursor described in the first aspect, and the sodium ion battery positive electrode material includes a positive electrode material core and a NASICON-type material coated on the surface of the positive electrode material core.

[0056] In one embodiment, based on the total mass of the sodium ion battery positive electrode material as 100%, the mass content of the NASICON-type material is 1% to 10%, for example, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9% or 10%, etc.

[0057] In a fourth aspect, the present application provides a method for preparing a sodium ion battery positive electrode material as described in the third aspect, the method comprising the following steps:

[0058] The sodium ion battery positive electrode material precursor and a sodium source are mixed and calcined to obtain the sodium ion battery positive electrode material.

[0059] The present application does not specifically limit the type of sodium source, and it can be, for example, sodium carbonate.

[0060] In one embodiment, the calcination temperature is 800°C to 1000°C, for example, 800°C, 825°C, 850°C, 870°C, 880°C, 900°C, 950°C or 1000°C.

[0061] In one embodiment, the calcination time is 12 hours to 20 hours, for example, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 18 hours or 20 hours.

[0062] In a fifth aspect, the present application provides a sodium ion battery, which includes the sodium ion battery positive electrode material described in the third aspect.

[0063] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to limited space and for the sake of simplicity, this application no longer exhaustively lists the specific point values ​​included in the range.

[0064] Compared with the existing technology, this application has the following beneficial effects:

[0065] (1) The present application combines a NASICON-type material precursor and a positive electrode material precursor to form a positive electrode material precursor for a sodium ion battery, effectively improving the sodium ion migration efficiency and sodium storage performance. It is further preferred to coat the NASICON-type material on the surface of the positive electrode material, thereby improving the uniformity of the coating layer and significantly improving the cycle performance and rate performance of the material. At the same time, the present application solves the drawbacks of poor air and water stability of the coating in the sintering stage of the back-end positive electrode material by combining an ordinary positive electrode material precursor with a NASICON-type material precursor at the precursor end, thereby reducing the complexity of the subsequent process and reducing production costs.

[0066] (2) The sodium ion battery positive electrode material precursor described in this application is used to prepare the sodium ion battery positive electrode material, which can effectively improve the cycle stability and rate performance of the sodium ion battery. Its rate performance is above 90%, and the capacity retention rate after 500 cycles is above 91%.

[0067] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0069] FIG1 is a SEM image of the coated sodium ion battery positive electrode material precursor in Example 1. DETAILED DESCRIPTION

[0070] The technical solution of the present application will be further explained below with reference to the accompanying drawings and through specific implementation methods.

[0071] In the embodiment of the present application, the positive electrode material precursor is Ni 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2 is used as an example and is not limited to this chemical formula. Other cathode material precursors commonly used in the art are also applicable to this application.

[0072] Example 1

[0073] This embodiment provides a sodium ion battery positive electrode material precursor, including a positive electrode material precursor and a NASICON type material precursor; the NASICON type material precursor is a substance converted into a NASICON type material after calcination. The positive electrode material precursor is a quaternary layered oxide positive electrode material precursor with a chemical formula of Ni 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2 (denoted as NFCM precursor), the chemical formula of NASICON type material is NaMg 0.2 Zr 0.2 Ti 1.6 (PO4)3.

[0074] This embodiment also provides a method for preparing the above-mentioned sodium ion battery positive electrode material precursor, comprising the following steps:

[0075] Step 1: nickel sulfate, ferrous sulfate, copper sulfate, and manganese sulfate are prepared in a metal molar ratio of 1:1:1:1 to prepare a nickel-iron-copper-manganese metal salt solution A with a total metal ion concentration of 1 mol / L;

[0076] Prepare 0.05 mol / L EDTA solution as complexing agent B;

[0077] 32% industrial liquid alkali is used as precipitant C.

[0078] Step 2: Add 6000L of pure water to an 8000L reactor, add liquid alkali and complexing agent EDTA to prepare the base solution to pH 11.6, the EDTA concentration is 0.01mol / L, heat to 38°C and continuously introduce nitrogen for protection. Add the mixed solution A, complexing agent B, and precipitant C to the reactor at a flow rate of 400L / h, 100L / h, and 130L / h, respectively, to maintain the reaction pH at 11.6, the complexing agent concentration at 0.01mol / L, and the stirring speed at 500rpm. After 50h of reaction, stop feeding to obtain Ni 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2 precursor.

[0079] Step 3: Phosphoric acid, magnesium sulfate, zirconium sulfate and titanyl sulfate are respectively prepared into 0.5 mol / L aqueous solutions, and 17% ammonia aqueous solution is fed at 60 L / h, 20 L / h, 20 L / h, 160 L / h, and 30 L / h for 1 hour to obtain a coated sodium ion battery positive electrode material precursor.

[0080] This embodiment also provides a sodium ion battery positive electrode material, the preparation method of which includes the following steps:

[0081] The coated sodium ion battery cathode material precursor and sodium carbonate were mixed evenly and calcined at 800 ° C for 20 h to obtain a sodium ion battery cathode material. The sodium ion battery cathode material includes NFCM1111 quaternary layered oxide cathode material (chemical formula is NaNi 0.25 Fe 0.25 Cu 0.25 Mn 0.25 O2) and NaMg coated on its surface 0.2 Zr 0.2 Ti 1.6 (PO4)3. Taking the total mass of the positive electrode material of sodium ion battery as 100%, NaMg 0.2 Zr 0.2 Ti 1.6 The mass content of (PO4)3 is 2%.

[0082] Figure 1 is an SEM image of the coated precursor. It can be seen from the figure that the NASICON material precursor is evenly coated on the NFCM precursor.

[0083] Example 2

[0084] This embodiment provides a sodium ion battery positive electrode material precursor, including a positive electrode material precursor and a NASICON type material precursor; the NASICON type material precursor is a substance converted into a NASICON type material after calcination. The positive electrode material precursor is a quaternary layered oxide positive electrode material precursor with a chemical formula of Ni 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2, the chemical formula of NASICON type material is NaMg 0.2 Zr 0.2 Ti 1.6 (PO4)3.

[0085] This embodiment also provides a method for preparing the above-mentioned sodium ion battery positive electrode material precursor, comprising the following steps:

[0086] Step 1: nickel sulfate, ferrous sulfate, copper sulfate, and manganese sulfate are prepared in a metal molar ratio of 1:1:1:1 to prepare a nickel-iron-copper-manganese metal salt solution A with a total metal ion concentration of 2 mol / L;

[0087] Prepare 0.1 mol / L EDTA solution as complexing agent B;

[0088] 32% industrial liquid alkali is used as precipitant C.

[0089] Step 2: Add 6000L of pure water to an 8000L reactor, add liquid alkali and complexing agent EDTA to prepare the base solution to pH 11.0, the EDTA concentration is 0.05mol / L, heat to 50°C and continuously introduce nitrogen for protection. Add the mixed solution A, complexing agent B, and precipitant C to the reactor at a flow rate of 400L / h, 100L / h, and 130L / h, respectively, to maintain the reaction pH at 11.0, the complexing agent concentration at 0.05mol / L, and the stirring speed at 300rpm. After 40h of reaction, stop feeding to obtain Ni 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2 precursor.

[0090] Step 3: Phosphoric acid, magnesium sulfate, zirconium sulfate and titanyl sulfate are respectively prepared into 1 mol / L aqueous solutions, and are continuously fed with 25% ammonia aqueous solution at 30 L / h, 10 L / h, 10 L / h, 100 L / h, and 18 L / h for 10 hours to obtain a coated sodium ion battery positive electrode material precursor.

[0091] This embodiment also provides a sodium ion battery positive electrode material, the preparation method of which includes the following steps:

[0092] The coated sodium ion battery cathode material precursor and sodium carbonate were mixed evenly and calcined at 950 ° C for 15 h to obtain a sodium ion battery cathode material. The sodium ion battery cathode material includes NFCM1111 quaternary layered oxide cathode material (chemical formula is NaNi 0.25 Fe 0.25 Cu 0.25 Mn 0.25 O2) and NaMg coated on its surface 0.2 Zr 0.2 Ti 1.6 (PO4)3. Taking the total mass of the positive electrode material of sodium ion battery as 100%, NaMg 0.2 Zr 0.2 Ti 1.6 The mass content of (PO4)3 is 7%.

[0093] Example 3

[0094] This embodiment provides a sodium ion battery positive electrode material precursor, including a positive electrode material precursor and a NASICON type material precursor; the NASICON type material precursor is a substance converted into a NASICON type material after calcination. The positive electrode material precursor is a quaternary layered oxide positive electrode material precursor with a chemical formula of Ni 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2, the chemical formula of NASICON type material is NaMg 0.2 Zr 0.2 Ti 1.6 (PO4)3.

[0095] This embodiment also provides a method for preparing the above-mentioned sodium ion battery positive electrode material precursor, comprising the following steps:

[0096] Step 1: nickel sulfate, ferrous sulfate, copper sulfate, and manganese sulfate are prepared in a metal molar ratio of 1:1:1:1 to prepare a nickel-iron-copper-manganese metal salt solution A with a total metal ion concentration of 2.5 mol / L;

[0097] Prepare a sodium pyrophosphate solution with a concentration of 0.08 mol / L as complexing agent B;

[0098] 32% industrial liquid alkali is used as precipitant C.

[0099] Step 2: Add 6000L of pure water to an 8000L reactor, add liquid alkali and complexing agent sodium pyrophosphate to prepare the bottom solution to pH 12.0, the sodium pyrophosphate concentration is 0.07mol / L, heat to 45°C and continuously introduce nitrogen for protection. The mixed solution A, complexing agent B, and precipitant C are continuously added to the reactor at a flow rate of 400L / h, 100L / h, and 130L / h, respectively, maintaining the reaction pH at 12.0, the complexing agent concentration at 0.07mol / L, and the stirring speed at 350rpm. After reacting for 35h, the feeding is suspended to obtain Ni 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2 precursor.

[0100] Step 3: Phosphoric acid, magnesium sulfate, zirconium sulfate and titanyl sulfate are respectively prepared into 0.6 mol / L aqueous solutions, and are continuously fed with 20% ammonia aqueous solution at 45 L / h, 15 L / h, 15 L / h, 140 L / h, and 20 L / h for 8 hours to obtain a coated sodium ion battery positive electrode material precursor.

[0101] This embodiment also provides a sodium ion battery positive electrode material, the preparation method of which includes the following steps:

[0102] The coated sodium ion battery cathode material precursor and sodium carbonate were mixed evenly and calcined at 900 ° C for 17 h to obtain a sodium ion battery cathode material. The sodium ion battery cathode material includes NFCM1111 quaternary layered oxide cathode material (chemical formula is NaNi 0.25 Fe 0.25 Cu 0.25 Mn 0.25 O2) and NaMg coated on its surface 0.2 Zr 0.2 Ti 1.6 (PO4)3. Taking the total mass of the positive electrode material of sodium ion battery as 100%, NaMg 0.2 Zr 0.2 Ti 1.6 The mass content of (PO4)3 is 10%.

[0103] Example 4

[0104] The difference from Example 1 is that the preparation parameters are adjusted so that the total mass of the sodium ion battery positive electrode material is 100%, NaMg 0.2 Zr 0.2Ti 1.6 The mass content of (PO4)3 is 0.5%.

[0105] Example 5

[0106] The difference from Example 1 is that the preparation parameters are adjusted so that the total mass of the sodium ion battery positive electrode material is 100%, NaMg 0.2 Zr 0.2 Ti 1.6 The mass content of (PO4)3 is 10.5%.

[0107] Comparative Example 1

[0108] The difference from Example 1 is that the chemical formula of the outer coating layer is NaMg 0.4 Zr 0.4 Ti 1.0 (PO4)3.

[0109] Comparative Example 2

[0110] The difference from Example 1 is that, in the preparation stage of the precursor of the positive electrode material for sodium ion batteries, step 3 is not performed, but the Ni prepared in step 2 is directly used. 0.25 Fe 0.25 Cu 0.25 Mn 0.25 (OH)2 precursor as a precursor of positive electrode material for sodium ion batteries.

[0111] test:

[0112] 1. Preparation of batteries

[0113] The positive electrode materials prepared in each embodiment and comparative example were used to prepare positive electrode sheets, and the preparation method was as follows:

[0114] The positive electrode material, conductive agent (carbon black), and binder (PVDF) were mixed in a mass ratio of 90:5:5 to create a positive electrode slurry, which was then coated onto aluminum foil to form a positive electrode sheet. A half-cell was assembled using sodium metal as the counter electrode, glass fiber as the separator, and an organic solution containing sodium perchlorate as the electrolyte. The electrochemical performance of the positive electrode material was then tested.

[0115] 2. Rate performance test: At 25°C, charge and discharge three times at 0.2C in the voltage range of 2V to 4.1V to obtain the discharge capacity C0 of the last cycle. Then, charge and discharge three times at 1C to obtain the discharge capacity C2 of the last cycle. The ratio of C2 / C0 is the rate performance.

[0116] 3. Cycling Performance Test: Cycling performance test was conducted at 25°C in the voltage range of 2.0V to 4.1V at 0.5C charge / 0.5C discharge. The capacity retention rate after 500 cycles was calculated as follows: Capacity Retention Rate = 500th Discharge Specific Capacity / First Discharge Specific Capacity × 100%.

[0117] The test results are shown in Table 1.

[0118] Table 1

[0119] As shown in Table 1, the present application combines a NASICON-type material precursor with a cathode material precursor to form a sodium-ion battery cathode material precursor, effectively improving sodium ion migration efficiency and sodium storage performance. Furthermore, the NASICON-type material is preferably coated on the surface of the cathode material, which improves the uniformity of the coating layer and thus significantly improves the material's cycle performance and rate performance.

[0120] Comparing Example 1 with Examples 4-5, it can be seen that NaMg in the positive electrode material 0.2 Zr 0.2 Ti 1.6 There is an optimal range for the coating amount of (PO)3. Less than 1% has a negative impact on the capacity retention rate, while more than 10% has a negative impact on the rate performance.

[0121] By comparing Example 1 and Comparative Example 1, it can be seen that the composition of the outer coating layer also affects the electrochemical performance. The coating layer can improve the interface between the material and the electrolyte, reduce side reactions, and the NASICON material can effectively improve the sodium ion migration efficiency.

[0122] Comparing Example 1 with Comparative Example 2, it can be seen that the present application combines a NASICON-type material precursor with a cathode material precursor to form a sodium-ion battery cathode material precursor, effectively improving sodium ion migration efficiency and sodium storage performance. Furthermore, the NASICON-type material is preferably coated on the surface of the cathode material, which improves the uniformity of the coating layer, thereby significantly improving the material's cycle performance and rate performance.

[0123] The applicant declares that while the above-mentioned embodiments are used to illustrate the detailed methods of the present application, the present application is not limited to the above-mentioned detailed methods, which does not mean that the present application must rely on the above-mentioned detailed methods in order to be implemented. Those skilled in the art should understand that any improvements to the present application, equivalent replacements for the raw materials of the present application's products, addition of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present application.

Claims

1. A sodium ion battery positive electrode material precursor, the sodium ion battery positive electrode material precursor comprising a positive electrode material precursor and a NASICON type material precursor; The NASICON type material precursor is a substance that is converted into a NASICON type material after calcination.

2. The sodium ion battery cathode material precursor according to claim 1, wherein: The positive electrode material precursor is a layered oxide positive electrode material precursor; Optionally, the cathode material precursor is a quaternary layered oxide cathode material precursor; Optionally, the chemical formula of the quaternary layered oxide cathode material is Ni a Fe b Cu c Mn d (OH)2, where 0 < a ≤ 0.4, 0 < b ≤ 0.4, 0 < c ≤ 0.3, 0 < d ≤ 0.6, and a + b + c + d = 1; Optionally, the NASICON type material is NaMg x Zr y Ti 1-x-y (PO4)3, where 0.1≤x≤0.3, 0.1≤y≤0.

3.

3. A method for preparing a sodium ion battery cathode material precursor as claimed in claim 1 or 2, the method comprising the following steps: The raw materials of the NASICON type material precursor are respectively prepared into aqueous solutions, and added into the reaction system containing the positive electrode material precursor in parallel with the ammonia solution to react, so as to obtain the positive electrode material precursor of the sodium ion battery.

4. The method according to claim 3, wherein: The raw materials of the NASICON type material precursor include phosphoric acid, magnesium salt, zirconium salt and titanium salt; Optionally, the concentration of the aqueous solution in step (1) is independently 0.1 mol / L to 1 mol / L; Optionally, the feed rate of the aqueous solution prepared with phosphoric acid is 30L / h to 90L / h; Optionally, the feed rate of the aqueous solution prepared with magnesium salt is 10L / h to 30L / h; Optionally, the feed rate of the aqueous solution prepared by the zirconium salt is 10L / h to 30L / h; Optionally, the feed rate of the aqueous solution prepared with titanium salt is 50L / h to 200L / h; Optionally, the mass concentration of the ammonia solution is 15% to 30%; Optionally, the feed rate of the aqueous ammonia solution is 5L / h to 30L / h; Optionally, the time of the parallel flow addition is 1h to 15h; Optionally, the cathode material precursor is a layered oxide cathode material; Optionally, the cathode material precursor is a quaternary layered oxide cathode material.

5. The method according to claim 3 or 4, wherein: The reaction system containing the positive electrode material precursor is: a reaction system for preparing the positive electrode material precursor by coprecipitation.

6. A sodium ion battery positive electrode material, wherein the sodium ion battery positive electrode material is prepared using the sodium ion battery positive electrode material precursor according to any one of claims 1 to 3, and the sodium ion battery positive electrode material comprises a positive electrode material core and a NASICON type material coated on the surface of the positive electrode material core.

7. The sodium ion battery positive electrode material according to claim 6, wherein Taking the total mass of the sodium ion battery positive electrode material as 100%, the mass content of the NASICON type material is 1% to 10%.

8. A method for preparing a positive electrode material for a sodium ion battery according to claim 6 or 7, the method comprising the following steps: The sodium ion battery positive electrode material precursor and a sodium source are mixed and calcined to obtain the sodium ion battery positive electrode material.

9. The method according to claim 8, wherein: The calcination temperature is 800°C to 1000°C; Optionally, the calcination time is 12 h to 20 h.

10. A sodium ion battery, comprising the sodium ion battery positive electrode material according to claim 6 or 7.

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