Nickel-iron-manganese-zinc precursor preparation method therefor, and use thereof

Abstract

A nickel-iron-manganese-zinc precursor, a preparation method therefor, and the use thereof. The preparation method comprises the following steps: concurrent flow addition of a nickel-iron-manganese-zinc salt solution, a precipitant solution, and a complexing agent solution into a base solution, and carrying out a coprecipitation reaction to obtain the nickel-iron-manganese-zinc precursor; wherein the complexing agent comprises sodium oxalate and / or sodium citrate. A certain amount of zinc is evenly doped in a metal layered oxide positive electrode material, and at least one among sodium oxalate and sodium citrate is selected during the preparation of the precursor to replace common the complexing agent aqueous ammonia, thus solving the problem of inconsistent precipitation speeds of ferrous ions with other metal ions when ammonia water is used as a complexing agent; simultaneously, the complexing speed is regulated and controlled by means of controlling reaction temperature, thus controlling metal ion precipitation speeds, thereby realizing further control of precursor morphology.

Description

A nickel-iron-manganese-zinc 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 nickel-iron-manganese-zinc precursor and a preparation method and application thereof. Background Art

[0002] With the continuous development of the economy and society, the depletion of non-renewable resources and the rapid deterioration of the ecological environment have become increasingly prominent. Although clean and renewable energy sources such as wind, hydro, and solar energy can provide a certain degree of substitution, their inherent shortcomings, such as low utilization rates and lack of recycling, have limited their development and application. In recent years, with the continuous development of the new energy industry, chemical batteries, represented by lithium batteries, have become a focus of attention due to their advantages such as high battery voltage, high energy density, rapid charge and discharge, and long cycle life. However, due to the extremely small and uneven distribution of lithium resources, coupled with the unstable price of lithium resources, the relatively low-cost sodium-ion battery is becoming increasingly popular. Sodium is abundant and widely available on Earth, and the raw material price is low and fluctuates little.

[0003] During the charge and discharge process of sodium ion batteries, sodium ions are inserted and removed, causing the layered transition metal to undergo structural changes or phase transitions, resulting in battery cycle attenuation. Therefore, in order to improve the stability of the positive electrode layered oxide material, a commonly used method is to modify the layered transition metal oxide by introducing active or inert elements for doping and substitution, thereby improving the stability of the positive electrode material during the charge and discharge process and increasing the conductivity of the material as much as possible.

[0004] Coprecipitation has become one of the mainstream methods for preparing cathode material precursors due to its advantages such as easy morphology control, low cost, and uniform product quality. Metal hydroxide precursors are typically obtained by controlled crystallization coprecipitation under a protective atmosphere using ammonia, sodium oxalate, or sodium citrate as a complexing agent. However, copper ions are prone to forming copper-ammonia complexes in ammonia complexing systems, resulting in coprecipitation failure.

[0005] CN116443955A doped a nickel-iron-manganese precursor with copper during its preparation and used sodium citrate as a complexing agent for metal ion coprecipitation. The resulting product was uniform and free of impurities. The resulting precursor exhibited high tap density and specific surface area, and exhibited excellent electrochemical performance.

[0006] CN107634196A prepares a salt solution of nickel, cobalt, manganese, lithium and zinc in a certain molar ratio, then uses ammonia as a complexing agent to obtain a mixture material through a direct precipitation method, and then obtains a zinc-doped ternary precursor material through subsequent spray drying and continuous heating. The prepared electrode material has good consistency, uniform composition and excellent discharge performance.

[0007] The above scheme can improve the performance of the precursor material to a certain extent through doping, but the morphology of the precursor obtained after doping is not ideal, resulting in a decrease in the cycle performance of the sodium battery positive electrode material.

[0008] Summary of the Invention

[0009] 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.

[0010] The purpose of the present application is to provide a nickel-iron-manganese-zinc precursor and its preparation method and application. The present application uniformly dopes a certain amount of zinc element inside the metal layered oxide positive electrode material and selects at least one of sodium oxalate and sodium citrate to replace the commonly used chelating agent ammonia water during the precursor preparation process, thereby effectively solving the problem of uneven particle element content caused by inconsistent precipitation rates of ferrous ions and other metal ions when ammonia water is used as a chelating agent. At the same time, the chelation rate is regulated by controlling the reaction temperature, thereby controlling the precipitation rate of metal ions, thereby achieving the purpose of further controlling the precursor morphology.

[0011] To achieve this goal, this application adopts the following technical solutions:

[0012] In a first aspect, the present application provides a method for preparing a nickel-iron-manganese-zinc precursor, the preparation method comprising the following steps:

[0013] injecting the nickel-iron-manganese-zinc salt solution, the precipitant solution and the complexing agent solution into the bottom liquid in parallel to carry out a co-precipitation reaction to obtain the nickel-iron-manganese-zinc precursor;

[0014] Wherein, the complexing agent includes sodium oxalate and / or sodium citrate.

[0015] The application uses sodium oxalate or sodium citrate to replace traditional ammonia as complexing agent, and on the one hand can utilize its strong reducing property, suppress the oxidation of ferrous ion and divalent manganese ion, prevent the generation of other substances affecting the precursor material purity, and then improve tap density.On the other hand, by temperature control the solubility of sodium oxalate or sodium citrate, and then control its complexing speed, further affect the precipitation speed of metal ion, ultimately reach the purpose of the properties such as specific surface area, tap density and sphericity of control precursor material.Evenly doped with an amount of zinc element in the precursor, zinc can not only allow the crystalline structure of material to be more stable, but also can indirectly provide capacity for material, while also improving the average charge and discharge voltage of material, and then improve the energy density of battery.

[0016] In one embodiment, the total concentration of metal ions in the nickel-iron-manganese-zinc salt solution is 1 to 5 mol / L, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L or 5 mol / L.

[0017] In one embodiment, the molar ratio of nickel, iron, manganese and zinc in the nickel-iron-manganese-zinc salt solution is x:y:z:c, wherein 0.2≤x≤0.5, 0.2≤y≤0.5, 0.2≤z≤0.5, 0.01≤c≤0.1, and x+y+z+c=1.

[0018] In one embodiment, the iron element in the nickel-iron-manganese-zinc salt solution includes ferrous ions.

[0019] In one embodiment, the precipitant solution comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0020] In one embodiment, the concentration of the precipitant solution is 2 to 15 mol / L, for example, 2 mol / L, 5 mol / L, 8 mol / L, 10 mol / L or 15 mol / L.

[0021] In one embodiment, the concentration of the complexing agent is 0.1 to 1.5 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 1.0 mol / L or 1.2 mol / L.

[0022] In one embodiment, the base solution includes a complexing agent and a precipitant.

[0023] In one embodiment, the concentration of the complexing agent in the base solution is 0.1 to 2 mol / L, for example, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L or 2 mol / L.

[0024] In one embodiment, the pH of the base solution is 9 to 12, for example, 9, 10, 11 or 12.

[0025] In one embodiment, the flow rate of the nickel-iron-manganese-zinc salt solution is 4 to 100 L / h, for example, 4 L / h, 10 L / h, 20 L / h, 50 L / h or 100 L / h.

[0026] In one embodiment, the co-precipitation reaction includes a one-step co-precipitation reaction and a two-step co-precipitation reaction.

[0027] In one embodiment, the temperature of the one-step coprecipitation reaction is 40-50°C, for example, 40°C, 42°C, 45°C, 48°C or 50°C.

[0028] In one embodiment, the temperature of the two-step co-precipitation reaction is 60-80°C, for example, 60°C, 65°C, 70°C, 75°C or 80°C.

[0029] In one embodiment, the pH of the coprecipitation reaction is 8 to 12, for example, 8, 9, 10, 11 or 12.

[0030] In one embodiment, the coprecipitation reaction time is 40 to 100 hours, for example, 40 hours, 50 hours, 60 hours, 80 hours or 100 hours.

[0031] In a second aspect, the present application provides a nickel-iron-manganese-zinc precursor, which is prepared by the method described in the first aspect.

[0032] In a third aspect, the present application provides a nickel-iron-manganese-zinc positive electrode material, which is prepared by mixing and sintering the nickel-iron-manganese-zinc precursor as described in the second aspect with a sodium source.

[0033] In a fourth aspect, the present application provides a sodium ion battery, which comprises the nickel-iron-manganese-zinc positive electrode material as described in the third aspect.

[0034] Compared with the prior art, this application has the following beneficial effects:

[0035] (1) This application improves the structural stability of the positive electrode material by uniformly doping a certain amount of zinc element within the metal layered oxide positive electrode material, thereby improving the material's cycle performance. In the precursor preparation process, at least one of sodium oxalate and sodium citrate is selected to replace the commonly used complexing agent ammonia water, effectively solving the problem of uneven particle element content caused by inconsistent precipitation rates of ferrous ions and other metal ions when ammonia water is used as a complexing agent. At the same time, by controlling the reaction temperature to regulate the complexing rate, thereby controlling the metal ion precipitation rate, the purpose of further controlling the precursor morphology is achieved.

[0036] (2) In the present application, a precursor material prepared by doping zinc element and using at least one of sodium oxalate and sodium citrate as a chelating agent is sintered to obtain a battery positive electrode material. In a battery cycle test, the battery is charged and discharged for more than 4,000 times, and the capacity retention rate reaches more than 82.2%, which is 10%-16% higher than the positive electrode material obtained by not doping zinc and using ammonia water as a chelating agent. DETAILED DESCRIPTION

[0037] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0038] Example 1

[0039] This embodiment provides a nickel-iron-manganese-zinc precursor, and the preparation method of the nickel-iron-manganese-zinc precursor is as follows:

[0040] Manganese sulfate, nickel sulfate, ferrous sulfate solution, and zinc sulfate solution were mixed to obtain a mixed metal salt solution with a total metal ion concentration of 4 mol / L and a molar ratio of nickel, iron, manganese, and zinc of 0.35:0.30:0.30:0.05. The mixed metal salt solution, 10 mol / L sodium hydroxide solution, and 6 mol / L sodium oxalate solution were added concurrently to a base solution with a pH of 11.50 and an oxalate concentration of 0.5 mol / L. During the parallel addition process, the feed rate of the mixed metal salt solution is 10 L / h. By controlling the flow rate of the sodium hydroxide solution and the sodium oxalate, the pH value of the reaction system is controlled between 9.8 and 10.5, and the oxalate concentration is controlled between 0.4 and 1 mol / L. Under nitrogen protection, the coprecipitation reaction is carried out for 80 hours. The reaction temperature is 45°C for the first 40 hours, and the reaction temperature is raised to 60°C during the subsequent stabilization period. The reaction is stopped when the average particle size reaches 5.0 μm. After the reaction is completed, the solution is centrifuged and washed, and then dried at 150°C to obtain the nickel-iron-manganese-zinc precursor.

[0041] The present application can adjust the solubility of sodium oxalate by adjusting the temperature of the coprecipitation reaction, thereby adjusting its complexation rate, further affecting the precipitation rate of metal ions, and ultimately achieving the purpose of controlling the specific surface area, tap density and sphericity of the precursor material.

[0042] Example 2

[0043] This embodiment provides a nickel-iron-manganese-zinc precursor, and the preparation method of the nickel-iron-manganese-zinc precursor is as follows:

[0044] Manganese sulfate, nickel sulfate, ferrous sulfate solution, and zinc sulfate solution were mixed to obtain a mixed metal salt solution with a total metal ion concentration of 1 mol / L and a molar ratio of nickel, iron, manganese, and zinc of 0.4:0.25:0.3:0.05. The mixed metal salt solution, 2 mol / L sodium hydroxide solution, and 4 mol / L sodium citrate solution were added concurrently to a base solution with a pH of 8.5 and a citrate concentration of 0.5 mol / L. During the parallel addition process, the feed rate of the mixed metal salt solution is 100 L / h. By controlling the flow rate of the sodium hydroxide solution and the sodium citrate, the pH value of the reaction system is controlled between 8.5 and 9.5, and the citrate concentration is controlled between 0.20 and 0.40 mol / L. Under nitrogen protection, the coprecipitation reaction is carried out for 80 hours. The reaction temperature is 45°C for the first 40 hours, and the reaction temperature is raised to 70°C during the subsequent stabilization period. The average particle size reaches 5.0 μm, and the reaction is stopped. After the reaction is completed, the solution is centrifuged and washed, and then dried at 150°C to obtain the nickel-iron-manganese-zinc precursor.

[0045] Example 3

[0046] This embodiment provides a nickel-iron-manganese-zinc precursor, and the preparation method of the nickel-iron-manganese-zinc precursor is as follows:

[0047] Manganese sulfate, nickel sulfate, ferrous sulfate solution, and zinc sulfate solution were mixed to obtain a mixed metal salt solution with a total metal ion concentration of 5 mol / L and a molar ratio of nickel, iron, manganese, and zinc of 0.28:0.5:0.2:0.02. The mixed metal salt solution, 15 mol / L sodium hydroxide solution, and 12 mol / L sodium oxalate solution were added concurrently to a base solution with a pH of 12 and an oxalate concentration of 0.8 mol / L. During the parallel addition process, the feed rate of the mixed metal salt solution is 4 L / h. By controlling the flow rate of the sodium hydroxide solution and the sodium oxalate, the pH value of the reaction system is controlled between 10.8 and 12, and the oxalate concentration is controlled between 1 and 1.5 mol / L. Under nitrogen protection, the coprecipitation reaction is carried out for 80 hours. The reaction temperature is 50°C for the first 40 hours, and the reaction temperature is raised to 80°C during the subsequent stabilization period. The reaction is stopped when the average particle size reaches 5.0 μm. After the reaction is completed, the solution is centrifuged and washed, and then dried at 150°C to obtain the nickel-iron-manganese-zinc precursor.

[0048] Example 4

[0049] The only difference between this embodiment and embodiment 1 is that the coprecipitation temperature is kept at 45° C., and the other conditions and parameters are exactly the same as those in embodiment 1.

[0050] Comparative Example 1

[0051] The only difference between this comparative example and Example 1 is that sodium oxalate is replaced with ammonia water, and the other conditions and parameters are exactly the same as those in Example 1.

[0052] Comparative Example 2

[0053] The only difference between this comparative example and Example 1 is that zinc is not added, the molar ratio of nickel, iron and manganese is 0.34:0.33:0.33, and the other conditions and parameters are exactly the same as those in Example 1.

[0054] Table 1 is a comparison of the finished product data of the products obtained in each example.

[0055] As can be seen from Table 1, during the preparation process of the precursor described in this application, a certain amount of zinc element is doped and sodium oxalate or sodium citrate is used as a chelating agent instead of ammonia water, which significantly increases the tap density of the precursor and reduces the specific surface area, thereby improving the cyclic stability of the precursor material.

[0056] Performance testing:

[0057] Sodium carbonate was uniformly mixed with the precursors prepared in the examples and comparative examples at a molar ratio of 1.06:1, calcined at 1100°C for 12 hours, and ground and sieved to obtain a sodium ion battery positive electrode material. At 25°C, the positive electrode material prepared above was used as the positive electrode main material and the metal sodium sheet was used as the negative electrode to assemble CR2032 button batteries. The electrochemical performance was then tested in the voltage range of 1.5-4.1V and at a discharge current density of 20mA / g. The test results of the capacity retention rate after 4000 cycles are shown in Table 2:

[0058] Table 2

[0059] As shown in Table 2, based on Examples 1-3, the present invention achieves a precursor by doping an appropriate amount of zinc during the coprecipitation reaction, using sodium oxalate or sodium citrate instead of ammonia as a complexing agent, and adjusting the reaction temperature in stages. During the subsequent charge-discharge process, the capacity retention rate exceeded 82.2% after 4000 cycles, demonstrating that these control measures effectively improved the cyclic performance of the precursor.

[0060] Comparing Examples 1 and 4, it can be seen that regulating the temperature at different stages, compared to maintaining a constant reaction temperature, improves the capacity retention rate by 10.1% after 4000 cycles. This application controls the complexation rate by adjusting the temperature of the coprecipitation reaction, thereby controlling the precipitation rate of metal ions, thereby further controlling and improving the precursor morphology. If the reaction temperature is maintained at a constant level, the precursor morphology will be too fine in the primary crystal form, resulting in an excessively large particle specific surface area and an excessively low tap density, ultimately affecting the battery's cycling performance.

[0061] As can be seen from the comparison of Example 1, Example 2 and Comparative Example 1, the present application uses sodium oxalate or sodium citrate instead of traditional ammonia as a complexing agent. On the one hand, the strong reducing property of oxalate can be used to inhibit the oxidation of ferrous ions and divalent manganese ions, prevent the generation of other substances that affect the purity of the precursor material, and thus improve the performance indicators of the precursor. On the other hand, the solubility of sodium oxalate or sodium citrate is controlled by temperature, thereby controlling its complexing rate, further affecting the precipitation rate of metal ions, and ultimately achieving the purpose of controlling the specific surface area, tap density, and sphericity of the precursor material.

[0062] Comparison of Example 1 and Comparative Example 2 demonstrates that the precursor described herein is uniformly doped with an appropriate amount of zinc. Zinc not only stabilizes the material's crystal structure but also indirectly contributes to its capacity, increasing the material's average charge and discharge voltage, thereby boosting the battery's energy density. Charge and discharge cycle testing demonstrated that the zinc-doped cathode material exhibited a 26.9% increase in late-stage capacity retention compared to the undoped cathode.

[0063] The applicant declares that the above is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Technical personnel in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technical personnel in the relevant technical field within the technical scope disclosed in this application fall within the protection scope and disclosure scope of this application.

Claims

1. A method for preparing a nickel-iron-manganese-zinc precursor, comprising the following steps: Injecting a nickel-iron-manganese-zinc salt solution, a precipitant solution, and a complexing agent solution into a bottom solution in parallel to carry out a coprecipitation reaction to obtain the nickel-iron-manganese-zinc precursor; wherein the complexing agent includes sodium oxalate and / or sodium citrate.

2. The preparation method according to claim 1, wherein, the total concentration of metal ions in the nickel-iron-manganese-zinc salt solution is 1-5 mol / L; Optionally, the molar ratio of nickel, iron, manganese, and zinc in the nickel-iron-manganese-zinc salt solution is x:y:z:c, where 0.2 ≤ x ≤ 0.5, 0.2 ≤ y ≤ 0.5, 0.2 ≤ z ≤ 0.5, 0.01 ≤ c ≤ 0.1, and x + y + z + c = 1; Optionally, the iron element in the nickel-iron-manganese-zinc salt solution includes ferrous ions.

3. The preparation method according to claim 1 or 2, wherein, the precipitant solution includes a sodium hydroxide solution and / or a potassium hydroxide solution; Optionally, the concentration of the precipitant solution is 2-15 mol / L.

4. The preparation method according to any one of claims 1-3, wherein, the concentration of the complexing agent is 0.1-1.5 mol / L.

5. The preparation method according to any one of claims 1-4, wherein, the bottom solution includes a complexing agent and a precipitant; Optionally, the concentration of the complexing agent in the bottom solution is 0.1-2 mol / L; Optionally, the pH of the bottom solution is 9-12.

6. The preparation method according to any one of claims 1-5, wherein, the flow rate of the nickel-iron-manganese-zinc salt solution is 4-100 L / h.

7. The preparation method according to any one of claims 1-6, wherein, the coprecipitation reaction includes a one-step coprecipitation and a two-step coprecipitation; Optionally, the temperature of the one-step coprecipitation reaction is 40-50 °C; Optionally, the temperature of the two-step coprecipitation reaction is 60-80 °C; Optionally, the pH of the coprecipitation reaction is 8-12; Optionally, the time of the coprecipitation reaction is 40-100 h.

8. A nickel-iron-manganese-zinc precursor obtained by the method according to any one of claims 1-7.

9. A nickel-iron-manganese-zinc cathode material prepared by mixing and sintering the nickel-iron-manganese-zinc precursor according to claim 8 with a sodium source.

10. A sodium-ion battery comprising the nickel-iron-manganese-zinc cathode material according to claim 9.

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