Method for preparing amorphous-state sodium ferric pyrophosphate / graphene composite positive electrode material by using jarosite slag leachate and application of amorphous-state sodium ferric pyrophosphate / graphene composite positive electrode material

Abstract

The invention discloses a method for preparing an iron-rich amorphous sodium iron pyrophosphate / graphene (NaFeP2O7 / rGO) composite positive electrode material by using a jarosite slag leaching solution and application of the iron-rich amorphous sodium iron pyrophosphate / graphene (NaFeP2O7 / rGO) composite positive electrode material. The preparation method comprises the following steps: (1) leaching the jarosite slag; (2) adjusting the concentration of iron ions and hydrogen ions in the jarosite slag leachate; (3) graphene oxide and Na4P2O7 are added into the jarosite slag leachate for a liquid phase precipitation reaction, and a precursor is obtained; and (4) sintering the precursor in an argon atmosphere to obtain the amorphous state NaFeP2O7 / rGO composite material. According to the method, iron resources in the iron vitriol slag are fully utilized, the prepared iron-rich amorphous NaFeP2O7 / rGO composite material serving as a sodium ion battery positive electrode material has good electrochemical performance, and the method is simple, low in cost, high in yield, easy in control of preparation conditions and suitable for large-scale production.

Description

Technical Field

[0001] The invention relates to the technical field of sodium ion battery positive electrode materials, and in particular to a method for preparing an iron-rich amorphous sodium iron pyrophosphate / graphene (NaFeP2O7 / rGO) composite positive electrode material by using an iron alum slag leaching solution and application thereof. Background Art

[0002] The efficient utilization of industrial waste is of great significance to the sustainable development of human society. The hydrometallurgical industry produces a large amount of iron alum slag every year. Iron alum slag is a dangerous industrial waste, which contains toxic components such as Zn, Pb, and Ca. At present, most iron alum slag is stored in landfills, occupying a large amount of land resources and posing a great risk of environmental pollution. The iron content in iron alum slag is as high as 29%. Therefore, the recovery and high-value utilization of high-content iron resources in iron alum slag are of great practical significance for the sustainable development of future society. Sodium-rich Na2FeP2O7 has been widely studied as a positive electrode material for sodium ion batteries. Since the valence state of Fe in sodium-rich Na2FeP2O7 is +2, its preparation process method is single, mainly solid-phase method, and the modification means are limited. The valence state of Fe in iron-rich NaFeP2O7 is +3, and its preparation method can be more diverse. However, there are few reports on the preparation and application of high-performance iron-rich amorphous NaFeP2O7 positive electrode materials for sodium ion batteries. To this end, the present invention proposes a method for preparing a novel iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material for sodium ion batteries using iron alum slag leachate. Summary of the invention

[0003] The object of the present invention is to provide a method and application of preparing iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material by utilizing iron alum slag leaching solution.

[0004] The specific steps are:

[0005] (1) leaching the iron alum slag under acidic conditions to obtain an iron alum slag leaching solution;

[0006] (2) adjusting the iron alum slag leaching solution obtained in step (1) to have an iron ion mass concentration of 0.26 mol / L and a hydrogen ion mass concentration of 1.23 mol / L;

[0007] (3) 20 mL of the iron alum slag leaching solution obtained in step (2) was measured and placed in a 200 mL beaker and heated to 70°C. 20 mL of distilled water was added to the beaker under stirring, and then 15 mL to 60 mL of GO dispersion with a mass concentration of 1 mg / mL was added to the beaker. After ultrasonic treatment for 0.5 hour, a Na4P2O7 solution with a mass concentration of 1 mol / L was added to the beaker until the pH of the solution in the beaker was about 2.0. After the obtained solution was allowed to stand at room temperature for 3 hours, the obtained precipitate was centrifuged and washed to neutrality, and then freeze-dried to constant weight to obtain a precursor;

[0008] (4) The precursor obtained in step (3) was transferred to a tube furnace, heated from room temperature to 400°C in an argon atmosphere at a heating rate of 2°C / min, and kept at 400°C for 6 hours to obtain an iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material.

[0009] The prepared NaFeP2O7 / rGO composite positive electrode material can be applied in the field of sodium ion batteries.

[0010] Advantages of the present invention: The present invention directly utilizes the leaching solution of iron alum slag to prepare a novel iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material for sodium ion batteries, which provides a new method for the resource utilization of industrial iron alum slag, reduces the waste of resources and pollution to the environment. At the same time, the prepared iron-rich amorphous NaFeP2O7 / rGO composite material has good cycle and rate performance as a positive electrode material for sodium ion batteries. In addition, the method of the present invention adopts a liquid phase precipitation method, which is simple, low-cost, high-yield, and easy-to-control preparation conditions, and is suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is the XRD spectrum of the NaFeP2O7 / rGO composite cathode material prepared in Examples 1 to 4.

[0012] Figure 2 This is the Raman spectrum of the NaFeP2O7 / rGO composite cathode material prepared in Examples 1 to 4.

[0013] Figure 3 This is the SEM image of the NaFeP2O7 / rGO composite positive electrode material prepared in Example 1.

[0014] Figure 4 This is the SEM image of the NaFeP2O7 / rGO composite positive electrode material prepared in Example 2.

[0015] Figure 5 This is the SEM image of the NaFeP2O7 / rGO composite positive electrode material prepared in Example 3.

[0016] Figure 6 This is the SEM image of the NaFeP2O7 / rGO composite positive electrode material prepared in Example 4.

[0017] Figure 7 This is a rate performance diagram of the NaFeP2O7 / rGO composite cathode material prepared in Examples 1 to 4.

[0018] Figure 8 This is a cycle performance diagram of the NaFeP2O7 / rGO composite cathode material prepared in Examples 1 to 4. DETAILED DESCRIPTION

[0019] 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.

[0020] Embodiment 1:

[0021] (1) using hydrochloric acid as a leaching agent to leach the iron alum slag to obtain an iron alum slag leachate;

[0022] (2) adjusting the iron alum slag leaching solution obtained in step (1) to have an iron ion mass concentration of 0.26 mol / L and a hydrogen ion mass concentration of 1.23 mol / L;

[0023] (3) 20 mL of the iron alum slag leaching solution obtained in step (2) was measured and placed in a 200 mL beaker and heated to 70°C. 20 mL of distilled water was added to the beaker under stirring, and then 15 mL of GO dispersion with a mass concentration of 1 mg / mL was added to the beaker. After ultrasonic treatment for 0.5 hour, a Na4P2O7 solution with a mass concentration of 1 mol / L was added to the beaker until the pH of the solution in the beaker was about 2.0. After the obtained solution was allowed to stand at room temperature for 3 hours, the obtained precipitate was centrifuged and washed to neutrality, and then freeze-dried to constant weight to obtain the precursor;

[0024] (4) The precursor obtained in step (3) was transferred to a tube furnace, heated from room temperature to 400°C in an argon atmosphere at a heating rate of 2°C / min, and kept at 400°C for 6 hours to obtain an iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material.

[0025] Embodiment 2:

[0026] (1) using hydrochloric acid as a leaching agent to leach the iron alum slag to obtain an iron alum slag leachate;

[0027] (2) adjusting the iron alum slag leaching solution obtained in step (1) to have an iron ion mass concentration of 0.26 mol / L and a hydrogen ion mass concentration of 1.23 mol / L;

[0028] (3) 20 mL of the iron alum slag leaching solution obtained in step (2) was measured and placed in a 200 mL beaker and heated to 70°C. 20 mL of distilled water was added to the beaker under stirring, and then 30 mL of GO dispersion with a mass concentration of 1 mg / mL was added to the beaker. After ultrasonic treatment for 0.5 hour, a Na4P2O7 solution with a mass concentration of 1 mol / L was added to the beaker until the pH of the solution in the beaker was about 2.0, and then the obtained solution was allowed to stand at room temperature for 3 hours. After the obtained solution was allowed to stand at room temperature for 3 hours, the obtained precipitate was centrifuged and washed to neutrality, and then freeze-dried to constant weight to obtain a precursor;

[0029] (4) The precursor obtained in step (3) was transferred to a tube furnace, heated from room temperature to 400°C in an argon atmosphere at a heating rate of 2°C / min, and kept at 400°C for 6 hours to obtain an iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material.

[0030] Embodiment 3:

[0031] (1) using hydrochloric acid as a leaching agent to leach the iron alum slag to obtain an iron alum slag leachate;

[0032] (2) adjusting the iron alum slag leaching solution obtained in step (1) to have an iron ion mass concentration of 0.26 mol / L and a hydrogen ion mass concentration of 1.23 mol / L;

[0033] (3) 20 mL of the iron alum slag leaching solution obtained in step (2) was measured and placed in a 200 mL beaker and heated to 70°C. 20 mL of distilled water was added to the beaker under stirring, and then 45 mL of GO dispersion with a mass concentration of 1 mg / mL was added to the beaker. After ultrasonic treatment for 0.5 hour, a Na4P2O7 solution with a mass concentration of 1 mol / L was added to the beaker until the pH of the solution in the beaker was about 2.0, and then the obtained solution was allowed to stand at room temperature for 3 hours. After the obtained solution was allowed to stand at room temperature for 3 hours, the obtained precipitate was centrifuged and washed to neutrality, and then freeze-dried to constant weight to obtain a precursor;

[0034] (4) The precursor obtained in step (3) was transferred to a tube furnace, heated from room temperature to 400°C in an argon atmosphere at a heating rate of 2°C / min, and kept at 400°C for 6 hours to obtain an iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material.

[0035] Embodiment 4:

[0036] (1) using hydrochloric acid as a leaching agent to leach the iron alum slag to obtain an iron alum slag leachate;

[0037] (2) adjusting the iron alum slag leaching solution obtained in step (1) to have an iron ion mass concentration of 0.26 mol / L and a hydrogen ion mass concentration of 1.23 mol / L;

[0038] (3) 20 mL of the iron alum slag leaching solution obtained in step (2) was measured and placed in a 200 mL beaker and heated to 70°C. 20 mL of distilled water was added to the beaker under stirring, and then 60 mL of GO dispersion with a mass concentration of 1 mg / mL was added to the beaker. After ultrasonic treatment for 0.5 hour, a Na4P2O7 solution with a mass concentration of 1 mol / L was added to the beaker until the pH of the solution in the beaker was about 2.0. After the obtained solution was allowed to stand at room temperature for 3 hours, the obtained precipitate was centrifuged and washed to neutrality, and then freeze-dried to constant weight to obtain the precursor;

[0039] (4) The precursor obtained in step (3) was transferred to a tube furnace, heated from room temperature to 400°C in an argon atmosphere at a heating rate of 2°C / min, and kept at 400°C for 6 hours to obtain an iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material.

[0040] The iron alum slag hydrochloric acid leaching solution used in Examples 1 to 4 is only an example, in order to enable those skilled in the art to better understand the present invention, but does not impose any limitation on the present invention.

[0041] Electrochemical performance test: The NaFeP2O7 / rGO composite cathode material prepared in the embodiment was used as the active material, the conductive carbon black (Super P) was used as the conductive agent, and the polyvinylidene fluoride (PVDF) was used as the binder. After being mixed and ground evenly in a mass ratio of 7:2:1, an appropriate amount of N-methyl-2-pyrrolidone (NMP) was added, and the mixture was evenly coated on an aluminum foil after being mixed into a slurry. The mixture was vacuum dried at 80 °C for 12 hours, and the electrode sheet was obtained after punching. The electrode sheet obtained after punching was used as the working electrode, the metal sodium sheet was used as the counter electrode, the glass fiber membrane (GF / D) was used as the diaphragm, and the 1 mol / L NaPF6 ethylene glycol dimethyl ether (DME) solution was used as the electrolyte. The CR2025 button cell was assembled in an argon-filled glove box. The constant current charge and discharge performance of the battery was tested using the BTS-5V / 10mA charge and discharge tester of Shenzhen Xinwei Company. The charge and discharge voltage range was 1.5~4.2 V, and the current density during the cycle performance test was 0.1 A g -1 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 Ag -1 , 0.5 A g -1 , 1.0 A g -1 and 2.0 A g -1 The electrochemical performance test results of Examples 1 to 4 are listed in Table 1 and Table 2.

[0042] Table 1: Rate performance test results of Examples 1 to 4

[0043]

[0044] Table 2: Cyclic performance test results of Examples 1 to 4

[0045]

[0046] Tables 1 and 2 respectively give the rate performance test and cycle performance test results of Examples 1 to 4. It can be seen from the table that the NaFeP2O7 / rGO composite electrode material prepared in Example 2 has better rate performance, and the NaFeP2O7 / rGO composite electrode material prepared in Example 3 has better cycle performance.

[0047] like Figure 1 The figure shows the XRD patterns of the NaFeP2O7 / rGO composite cathode materials prepared in Examples 1 to 4. As can be seen from the figure, the material prepared in the present invention is an iron-rich amorphous NaFeP2O7.

[0048] like Figure 2 The Raman spectra of the NaFeP2O7 / rGO composite cathode materials prepared in Examples 1 to 4 are shown. From the figure, it can be analyzed that the material prepared in the present invention contains rGO and is a NaFeP2O7 / rGO composite cathode material.

[0049] like Figures 3 to 6 , which is a SEM image of the NaFeP2O7 / rGO composite cathode material prepared in Examples 1 to 4. As can be seen from the figure, the NaFeP2O7 / rGO composite cathode material prepared in the present invention is composed of nano-NaFeP2O7 particles dispersed in rGO sheets.

[0050] like Figure 7 As shown in the figure, the NaFeP2O7 / rGO composite cathode materials prepared in Examples 1 to 4 are subjected to different current densities (0.05A g -1 , 0.1 A g -1 , 0.2 A g -1 , 0.3 A g -1 , 0.5 A g -1 , 1.0 A g-1 , 2.0 A g -1 As can be seen from the figure, Example 2 has a relatively better rate performance. -1 The current density is still 21.9 mAh g -1 The discharge capacity.

[0051] like Figure 8 As shown, the NaFeP2O7 / rGO composite cathode materials prepared in Examples 1 to 4 are -1 Cyclic performance curve under current density. It can be seen from the figure that Example 3 has relatively better cycle performance. -1 After 1000 cycles at the same current density, it still has a capacity of 78.7 mAh g -1 The discharge capacity.

Claims

1. A method for preparing an iron-rich amorphous sodium iron pyrophosphate / graphene (NaFeP2O7 / rGO) composite positive electrode material using an iron alum slag leachate, characterized in that: The specific steps are: (1) leaching the iron alum slag under acidic conditions to obtain an iron alum slag leaching solution; (2) adjusting the iron alum slag leaching solution obtained in step (1) to have an iron ion mass concentration of 0.26 mol / L and a hydrogen ion mass concentration of 1.23 mol / L; (3) 20 mL of the iron alum slag leaching solution obtained in step (2) was measured and placed in a 200 mL beaker and heated to 70 °C. 20 mL of distilled water was added to the beaker under stirring, and then 15 mL to 60 mL of GO dispersion with a mass concentration of 1 mg / mL was added to the beaker. After ultrasonic treatment for 0.5 hour, a Na4P2O7 solution with a mass concentration of 1 mol / L was added to the beaker until the pH of the solution in the beaker was about 2.

0. After the obtained solution was allowed to stand at room temperature for 3 hours, the obtained precipitate was centrifuged and washed to neutrality, and then freeze-dried to constant weight to obtain the precursor; (4) The precursor obtained in step (3) was transferred to a tube furnace, heated from room temperature to 400 °C in an argon atmosphere at a heating rate of 2 °C / min, and kept at 400 °C for 6 hours to obtain an iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material.

2. Application of the iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material prepared by the preparation method according to claim 1, characterized in that The iron-rich amorphous NaFeP2O7 / rGO composite positive electrode material can be used to prepare sodium ion batteries.

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