Preparation method of Na0. 7Fe0. 5Mn0. 5O2 positive electrode material for sodium ion battery

Abstract

The invention discloses a preparation method of a Na0. 7Fe0. 5Mn0. 5O2 positive electrode material for a sodium ion battery. The preparation method comprises the following steps: firstly, respectively weighing sodium nitrate, ferric nitrate nonahydrate and manganese acetate tetrahydrate according to the stoichiometric ratio of Na0. 7Fe0. 5Mn0. 5O2, and weighing oxalic acid according to the molar ratio of manganese acetate tetrahydrate to oxalic acid being 1: 8; dissolving the weighed four substances with a small amount of deionized water to obtain a homogeneous solution; and finally, putting the obtained homogeneous solution into a muffle furnace, and carrying out thermal decomposition at 800 DEG C to obtain the Na0. 7Fe0. 5Mn0. 5O2 positive electrode material. The method is simple and efficient, preparation conditions are easy to control, the method is suitable for large-scale production, and the prepared Na0. 7Fe0. 5Mn0. 5O2 positive electrode material has good sodium storage performance.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion battery positive electrode materials, and in particular to a sodium ion battery positive electrode material. 0.7 Fe 0.5 Mn 0.5 Preparation method of O2 positive electrode material. Background Art

[0002] At present, lithium-ion batteries have been widely used in electronic devices, electric vehicles and other fields. However, the high price and limited reserves of lithium have seriously restricted its further development. Since sodium has similar chemical properties to lithium and is widely distributed, sodium-ion batteries have been considered to be the most promising alternative to lithium-ion batteries and have received widespread attention in recent years. As an important positive electrode material for sodium-ion batteries, Na 0.7 Fe 0.5 Mn 0.5 O2 has a high theoretical specific capacity (260 mAh g -1 ), high energy density (~520 mWh g -1 ), low preparation cost and environmental friendliness, and has attracted widespread attention. 0.7 Fe 0.5 Mn 0.5 Common preparation methods for O2 cathode materials include high temperature solid phase method, sol-gel method and electrospinning method. The development of these methods is the key to the development of Na 0.7 Fe 0.5 Mn 0.5 The efficient preparation of O2 cathode materials provides a way, but they also have some disadvantages: for example, the product obtained by high-temperature sintering method has uneven particle size and low purity; the sol-gel process is relatively complicated; the electrospinning method has high equipment requirements and the nano-filament morphology is not easy to maintain during the sintering process. 0.7 Fe 0.5 Mn 0.5 The present invention provides a method for preparing a low-cost, simple and efficient NaO2 positive electrode material for sodium ion batteries. 0.7 Fe 0.5 Mn 0.5 A new approach to O2 cathode materials. Summary of the invention

[0003] The purpose of the present invention is to provide a low-cost, simple and efficient method for preparing Na 0.7 Fe 0.5 Mn 0.5 Method for O2 positive electrode material.

[0004] The specific steps are:

[0005] (1) Based on Na0.7 Fe 0.5 Mn 0.5 Sodium nitrate (NaNO3), ferric nitrate nonahydrate (FeNO3·9H2O) and manganese acetate tetrahydrate (Mn(CH3OO)2·4H2O) were weighed according to the molar ratio of Na:Fe:Mn=7:5:5 for the stoichiometric ratio of O2, and oxalic acid was weighed according to the molar ratio of manganese acetate tetrahydrate to oxalic acid (H2C2O4·2H2O) of 1:8.

[0006] (2) slowly adding the four substances weighed in step (1) into deionized water, and mechanically stirring the mixture to completely dissolve to obtain a homogeneous solution;

[0007] (3) The homogeneous solution obtained in step (2) is transferred into a crucible, and then the crucible is placed in a muffle furnace, and heated from room temperature to 800°C at a heating rate of 5°C / min in an air atmosphere, and kept at 800°C for 4 to 10 hours, and then cooled to room temperature with the furnace to obtain Na 0.7 Fe 0.5 Mn 0.5 O2 positive electrode material.

[0008] The advantages of the present invention are: the method of the present invention is simple and efficient, the preparation conditions are easy to control, and it is suitable for large-scale production. 0.7 Fe 0.5 Mn 0.5 O2 positive electrode material as a positive electrode material for sodium ion batteries has good cycle performance and rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a diagram of Na prepared in Examples 1 to 4. 0.7 Fe 0.5 Mn 0.5 XRD pattern of O2 positive electrode material.

[0010] Figure 2 The Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 Rate performance diagram of O2 cathode material.

[0011] Figure 3 The Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 Cycling performance diagram of O2 positive electrode material. DETAILED DESCRIPTION

[0012] The present invention is further described below in conjunction with specific embodiments. It should be pointed out that the following embodiments are for those skilled in the art to better understand the present invention, rather than limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above content.

[0013] Embodiment 1:

[0014] (1) Based on Na 0.7 Fe 0.5 Mn 0.5 The stoichiometric ratio of O2 was based on the molar ratio of Na:Fe:Mn=7:5:5, and 0.0028 mol of sodium nitrate (NaNO3), 0.002 mol of ferric nitrate nonahydrate (FeNO3·9H2O) and 0.002 mol of manganese acetate tetrahydrate (Mn(CH3OO)2·4H2O) were weighed respectively. In addition, 2.0 g of oxalic acid was weighed according to the molar ratio of manganese acetate tetrahydrate to oxalic acid (H2C2O4·2H2O) of 1:8.

[0015] (2) Slowly add the four substances weighed in step (1) into 10 mL of deionized water and mechanically stir the mixture to completely dissolve to obtain a homogeneous solution;

[0016] (3) The homogeneous solution obtained in step (2) was transferred into a crucible, and then the crucible was placed in a muffle furnace, and heated from room temperature to 800°C at a heating rate of 5°C / min in an air atmosphere, and kept at 800°C for 4 hours, and then cooled to room temperature with the furnace to obtain Na 0.7 Fe 0.5 Mn 0.5 O2 positive electrode material.

[0017] Embodiment 2:

[0018] (1) Based on Na 0.7 Fe 0.5 Mn 0.5 The stoichiometric ratio of O2 was based on the molar ratio of Na:Fe:Mn=7:5:5, and 0.0028 mol of sodium nitrate (NaNO3), 0.002 mol of ferric nitrate nonahydrate (FeNO3·9H2O) and 0.002 mol of manganese acetate tetrahydrate (Mn(CH3OO)2·4H2O) were weighed respectively. In addition, 2.0 g of oxalic acid was weighed according to the molar ratio of manganese acetate tetrahydrate to oxalic acid (H2C2O4·2H2O) of 1:8.

[0019] (2) Slowly add the four substances weighed in step (1) into 10 mL of deionized water and mechanically stir the mixture to completely dissolve to obtain a homogeneous solution;

[0020] (3) The homogeneous solution obtained in step (2) was transferred into a crucible, and then the crucible was placed in a muffle furnace, and heated from room temperature to 800°C at a heating rate of 5°C / min in an air atmosphere, and kept at 800°C for 6 hours, and then cooled to room temperature with the furnace to obtain Na 0.7 Fe 0.5 Mn 0.5 O2 positive electrode material.

[0021] Embodiment 3:

[0022] (1) Based on Na 0.7 Fe 0.5 Mn 0.5 The stoichiometric ratio of O2 was based on the molar ratio of Na:Fe:Mn=7:5:5, and 0.0028 mol of sodium nitrate (NaNO3), 0.002 mol of ferric nitrate nonahydrate (FeNO3·9H2O) and 0.002 mol of manganese acetate tetrahydrate (Mn(CH3OO)2·4H2O) were weighed respectively. In addition, 2.0 g of oxalic acid was weighed according to the molar ratio of manganese acetate tetrahydrate to oxalic acid (H2C2O4·2H2O) of 1:8.

[0023] (2) Slowly add the four substances weighed in step (1) into 10 mL of deionized water and mechanically stir the mixture to completely dissolve to obtain a homogeneous solution;

[0024] (3) The homogeneous solution obtained in step (2) was transferred into a crucible, and then the crucible was placed in a muffle furnace, and heated from room temperature to 800°C at a heating rate of 5°C / min in an air atmosphere, and kept at 800°C for 8 hours, and then cooled to room temperature to obtain Na 0.7 Fe 0.5 Mn 0.5 O2 positive electrode material.

[0025] Embodiment 4:

[0026] (1) According to Na 0.7 Fe 0.5 Mn 0.5 The stoichiometric ratio of O2 was 0.0028 mol sodium nitrate (NaNO3), 0.002 mol ferric nitrate nonahydrate (FeNO3·9H2O) and 0.002 mol manganese acetate tetrahydrate (Mn(CH3OO)2·4H2O), and 2.0 g oxalic acid was weighed in a molar ratio of 1:8 between manganese acetate tetrahydrate and oxalic acid (H2C2O4·2H2O).

[0027] (2) Slowly add the four substances weighed in step (1) into 10 mL of deionized water and mechanically stir the mixture to completely dissolve to obtain a homogeneous solution;

[0028] (3) The homogeneous solution obtained in step (2) was transferred to a crucible, and then the crucible was placed in a muffle furnace, heated from room temperature to 800°C at a heating rate of 5°C / min in an air atmosphere, and kept at 800°C for 10 hours, and then cooled to room temperature to obtain Na 0.7 Fe 0.5 Mn 0.5 O2 positive electrode material.

[0029] Electrochemical performance test: The Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 O2 material as active material, conductive carbon black (Super P) as conductive agent, polyvinylidene fluoride (PVDF) as binder were mixed and ground in a mass ratio of 7:2:1, and then an appropriate amount of N-methyl-2-pyrrolidone (NMP) was added. After mixing into a slurry, it was evenly coated on aluminum foil, vacuum dried at 80 °C for 12 hours, and punched to obtain an electrode sheet. The punched electrode sheet was used as the positive electrode, the metal sodium sheet was used as the negative electrode, the glass fiber was used as the separator, and 1 mol L -1 NaClO4 was dissolved in a 1:1 volume ratio of ethylene carbonate and diethyl carbonate solution as the electrolyte and assembled into a CR2025 button cell in an argon-filled glove box. The constant current charge and discharge performance of the battery was tested using a BTS-5V / 10mA charge and discharge tester from Shenzhen Xinwei Company. The charge and discharge voltage range was 1.5~4.2 V, and the current density of the rate performance test was 0.05 A g -1 , 0.1 A g -1 , 0.2 A g -1 , 0.3 A g -1 , 0.5 A g -1 , and 0.1 A g -1 The current density during the cycle performance test was 0.05 A g -1 The Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 The rate performance and cycle performance test results of O2 cathode materials are listed in Table 1 and Table 2, respectively.

[0030] Table 1: Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 Rate performance test results of O2 cathode materials

[0031]

[0032] Table 2: Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn0.5 Cyclic performance test results of O2 cathode materials

[0033]

[0034] Table 1 and Table 2 respectively give the preparation methods of Na in Examples 1 to 4. 0.7 Fe 0.5 Mn 0.5 The rate performance test and cycle performance test results of O2 materials as positive electrode materials for sodium ion batteries show that the Na 0.7 Fe 0.5 Mn 0.5 All O2 positive electrode materials have good sodium storage performance, among which Example 3 has relatively better sodium storage performance.

[0035] As shown in Figure 1, the Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 XRD spectrum of O2 positive electrode material. It can be seen from the figure that the material prepared by the present invention is a layered transition metal oxide Na 0.7 Fe 0.5 Mn 0.5 O2, except the diffraction peaks of P2 phase and P3 phase, there are no other obvious impurity peaks.

[0036] like Figure 2 As shown, the Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 O2 cathode materials at different current densities (0.05, 0.1, 0.2, 0.3, 0.5, 0.1 A g -1 ) under the rate performance curve. As can be seen from the figure, the Na prepared in Example 3 0.7 Fe 0.5 Mn 0.5 O2 cathode material has relatively better rate performance at 0.2 A g -1 and 0.5 A g -1 The current density is 102 mAh g -1 and 70 mAh g -1 The discharge capacity.

[0037] like Figure 3 As shown, the Na prepared in Examples 1 to 4 0.7 Fe 0.5 Mn 0.5 O2 cathode material at 0.05 A g -1 Cyclic performance curve under current density. It can be seen from the figure that the Na prepared in Example 3 0.7 Fe0.5 Mn 0.5 O2 cathode material has relatively better cycle performance at 0.05 A g -1 After 200 cycles at the same current density, the discharge capacity remains at 42 mAh g -1 .

Claims

1. A sodium ion battery with Na 0.7 Fe 0.5 Mn 0.5 The preparation method of O2 positive electrode material is characterized in that The specific steps are: (1) Based on Na 0.7 Fe 0.5 Mn 0.5 Sodium nitrate (NaNO3), ferric nitrate nonahydrate (FeNO3·9H2O) and manganese acetate tetrahydrate (Mn(CH3OO)2·4H2O) were weighed according to the molar ratio of Na:Fe:Mn=7:5:5 for the stoichiometric ratio of O2, and oxalic acid was weighed according to the molar ratio of manganese acetate tetrahydrate to oxalic acid (H2C2O4·2H2O) of 1:8; (2) slowly adding the four substances weighed in step (1) into deionized water, and mechanically stirring the mixture to completely dissolve to obtain a homogeneous solution; (3) The homogeneous solution obtained in step (2) is transferred into a crucible, and then the crucible is placed in a muffle furnace, and heated from room temperature to 800°C at a heating rate of 5°C / min in an air atmosphere, and kept at 800°C for 4 to 10 hours, and then cooled to room temperature with the furnace to obtain Na 0.7 Fe 0.5 Mn 0.5 O2 positive electrode material.

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