Precursor of sodium ion battery positive electrode material as well as preparation method and application of precursor
By adding styrene phosphonic acid to the co-precipitation reaction of the positive electrode material of sodium ion battery, a precursor with a specific morphology and structure was prepared, which solved the problem of low energy density of sodium ion battery, improved the cycling performance and energy density of the battery, and was suitable for the high-end market.
Patent Information
- Application Number
- CN202411876575.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-05-06
AI Technical Summary
The low energy density of sodium ion batteries limits their applications in the high-end market.
By adding styrene phosphonic acid to the co-precipitation reaction, the morphology and structure of the precursor are regulated, and a precursor with a specific morphology and structure is prepared.
It improves the circulation performance of the positive electrode material of sodium ion battery, enhances the energy density of the battery, and is suitable for the high-end market.
Smart Images
Figure CN119929911A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of sodium ion battery materials, and in particular relates to a sodium ion battery precursor and a preparation method and application thereof. Background Art
[0002] As the global demand for clean energy continues to grow, energy storage technology is becoming increasingly important in the new energy system. As a storage technology with great potential, sodium-ion batteries show broad development prospects due to their abundant raw materials, low manufacturing costs, and strong temperature adaptability. From a technical point of view, although sodium-ion batteries may be slightly inferior to lithium batteries in terms of capacity density and cycle life, their significant cost advantages make them still highly competitive in the market. Especially in terms of safety and stability, sodium-ion batteries perform well, so they have become a viable option in the mid- and low-end electric vehicle market, especially in areas where battery density requirements are not high. However, its relatively low energy density still limits its application in the high-end market.
[0003] Sodium-ion battery cathode material is one of the key materials for sodium-ion batteries. At present, there are three major technical routes for sodium-ion battery cathode materials, namely layered oxides, Prussian materials and polyanion compounds. Each of the three technical routes has its own advantages and disadvantages, but in general, the material that is currently widely studied and first mass-produced is most likely layered oxides, which have similar material preparation processes to ternary materials and are progressing rapidly in industrialization.
[0004] CN118908309A discloses a high specific surface layer oxide positive electrode material precursor for sodium ion battery, wherein a mixed metal salt solution, a precipitant and a complexing agent are introduced into a reactor with a prepared bottom liquid for coprecipitation reaction, and process parameters such as reaction temperature, pH, complexing agent concentration and oxidizing gas content are controlled, and the reaction is continued until the particle size of the product reaches the target particle size to obtain a sodium positive electrode material precursor. By introducing oxidizing gas and controlling the oxidizing gas content in the reactor during the liquid phase coprecipitation process, the refinement degree of the primary particles of the sodium precursor is effectively regulated, and the obtained small particle sodium precursor has a relatively refined particle morphology and a relatively high specific surface area.
[0005] CN118771484A discloses a method for preparing a core-shell structure sodium positive electrode precursor, comprising: (1) introducing a first mixed metal salt solution, a precipitant and a complexing agent into a base liquid to carry out a first coprecipitation reaction; the first mixed metal salt solution comprises a core formula amount of Ni source, Fe source, Mn source and M source; (2) after the first coprecipitation reaction in step (1) is completed, replacing the first mixed metal salt solution with a second metal salt solution and introducing it into the reaction system to carry out a second coprecipitation reaction to obtain the core-shell structure sodium positive electrode precursor; the second mixed metal salt solution comprises a shell formula amount of Ni source, Cu source, Fe source, Mn source and N source; the core primary particles of the precursor are densely stacked, and the shell primary particles are loosely stacked.
[0006] Layered oxide cathode materials can inherit the morphology and structural characteristics of their precursors, and the research on their precursors is of great significance. Summary of the invention
[0007] The purpose of the present invention is to provide a precursor of a sodium ion battery positive electrode material and a preparation method and application thereof.
[0008] The present invention provides the following specific technical solutions.
[0009] First, the present invention provides a method for preparing a precursor of a positive electrode material for a sodium ion battery, comprising: A mixed metal salt solution containing nickel ions, iron ions, and manganese ions, a styrenephosphonic acid solution, a precipitant solution, and a complexing agent solution are simultaneously introduced into the bottom liquid of the reaction kettle to carry out a coprecipitation reaction in a protective atmosphere, and the pH value of the reaction system is controlled to be 11±0.5 and the temperature to be 55-65°C; When the particle size D50 of the reaction slurry reaches the target value, the reaction is stopped; The reaction slurry is subjected to solid-liquid separation, and the solid phase is washed, dried, and sieved to obtain a precursor.
[0010] In a further preferred embodiment, the molar ratio of nickel ions, iron ions and manganese ions in the mixed metal salt solution is based on the chemical formula Ni x Fe y Mn z (OH)2 is determined, where 0.25≤x≤0.5, 0≤y≤0.5, 0.25≤z≤0.5, and x+y+z=1.
[0011] In a further preferred embodiment, the total concentration of nickel ions, iron ions and manganese ions in the mixed metal salt solution is 1-3 mol / L.
[0012] In a further preferred embodiment, the concentration of the styrenephosphonic acid solution is 400-1000 mg / L.
[0013] In a further preferred embodiment, the precipitant is at least one of NaOH, KOH and LiOH. Preferably, the concentration of the precipitant solution is 2-5 mol / L.
[0014] In a further preferred embodiment, the complexing agent solution is a 0.8-3 mol / L ammonia solution.
[0015] In a further preferred embodiment, during the coprecipitation reaction, the concentration of ammonia in the reaction system is 0.5-2 mol / L.
[0016] In a further preferred embodiment, the flow rates of the mixed metal salt solution and the styrenephosphonic acid solution are 3-5 L / h and 10-25 mL / h, respectively.
[0017] In a further preferred embodiment, the pH value of the reaction kettle bottom liquid is 10.5-11.5, and the temperature is 55-65°C.
[0018] In a further preferred embodiment, the target value of the particle size D50 of the reaction slurry is 1 to 6 microns.
[0019] Based on the same inventive concept, the present invention provides a precursor prepared by the above preparation method.
[0020] In addition, the present invention provides a sodium ion battery positive electrode material, which is obtained by mixing the above precursor with a sodium source and sintering them.
[0021] The present invention also provides a sodium ion battery, comprising the above-mentioned positive electrode material.
[0022] In the coprecipitation reaction system, the hydroxyl layer on the surface of the precursor crystal undergoes a deprotonation reaction, and the oxygen atoms exposed on the crystal surface can produce stronger hydrogen bonds with the hydroxyl groups on the metal complex ions, thereby enhancing the adsorption capacity of metal ammine complex ions. In the present invention, styrenephosphonic acid is added during the formation of the primary crystal of the precursor, which can specifically bond with the transition metal atoms exposed on the crystal surface, hinder the adsorption of metal ammine complex ions on certain crystal surfaces, thereby reducing the growth rate of the crystal surface, and obtaining a precursor with a specific morphology and structure.
[0023] Compared with the prior art, the above one or more technical solutions of the present invention can achieve at least one of the following beneficial effects: The method for preparing the precursor provided by the present invention can adopt the existing co-precipitation reaction system, equipment, etc., without significantly increasing the site and system costs.
[0024] The present invention adopts a relatively mature coprecipitation process in the art, and only adds styrene phosphonic acid during the coprecipitation process. The preparation method has strong operability and does not impose a large burden on operators.
[0025] The precursor prepared by the present invention is a spherical structure formed by orderly stacking of thick rod-shaped crystal layers. After the positive electrode material inherits this morphology, the cycle performance of the sodium ion battery can be improved. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 This is the SEM image of the precursor obtained in Example 1.
[0027] Figure 2 This is the SEM image of the precursor obtained in Comparative Example 1.
[0028] Figure 3 This is the SEM image of the precursor obtained in Comparative Example 2.
[0029] Figure 4 This is the SEM image of the precursor obtained in Comparative Example 3.
[0030] Figure 5 This is the SEM image of the precursor obtained in Example 2.
[0031] Figure 6 This is the SEM image of the precursor obtained in Example 3.
[0032] Figure 7 This is the cycle performance diagram of the battery. DETAILED DESCRIPTION
[0033] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.
[0034] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.
[0035] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.
[0036] Example 1 A mixed salt solution was prepared in which the molar ratio of nickel ions, iron ions and manganese ions was 0.33:0.33:0.34 and the total concentration of nickel ions, iron ions and manganese ions was 2 mol / L.
[0037] Prepare a 600 mg / L styrenephosphonic acid solution.
[0038] Prepare a NaOH solution with a concentration of 2.5 mol / L as a precipitant solution.
[0039] An ammonia solution with a concentration of 1 mol / L was prepared as a complexing agent solution.
[0040] Preparation of reactor bottom liquid: The pH value of the reactor bottom liquid is 10.8 and the temperature is 60°C.
[0041] The air in the reactor was evacuated and nitrogen was continuously introduced.
[0042] The mixed salt solution, styrenephosphonic acid solution, precipitant solution and complexing agent solution are simultaneously introduced into the bottom liquid of the reaction kettle and stirred to carry out a coprecipitation reaction. The pH value of the reaction system is controlled to be 11, the temperature is 60°C, and the ammonia concentration is 1.5 mol / L; the flow rate of the mixed salt solution is 4 L / h, and the flow rate of the styrenephosphonic acid solution is 15 mL / L.
[0043] When the particle size D50 of the reaction slurry reaches 2.0±0.5 μm, the introduction of the reaction raw materials is stopped and the reaction is stopped.
[0044] The reaction slurry is centrifuged and washed, the solid phase is further washed, and then the solid phase is dried and the iron is sieved out to obtain a precursor.
[0045] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that no styrenephosphonic acid solution is introduced during the coprecipitation reaction.
[0046] Figure 1 This is the SEM image of the precursor obtained in Example 1. Figure 2 The SEM image of the precursor obtained in the comparative example. It can be seen that in Example 1, by adding styrenephosphonic acid during the synthesis process, the precursor primary particles synthesized are long rod-shaped, thick, and the secondary particles are spherical, with few surface pores, and the secondary particles are obviously densified. The primary particles of the precursor obtained in Comparative Example 1 are in the form of flakes, and the secondary particles are obtained by disordered accumulation to obtain spherical particles.
[0047] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that phosphoric acid is used instead of styrenephosphonic acid.
[0048] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that ammonium phosphate is used instead of styrenephosphonic acid.
[0049] Figure 3 and Figure 4 The SEM images of the precursors obtained in Comparative Examples 2 and 3 respectively show that the use of phosphoric acid / ammonium phosphate as an additive does not change the morphology of the precursors, and the primary particles of the precursors are in the form of thin flakes.
[0050] Example 2 A mixed salt solution was prepared in which the molar ratio of nickel ions, iron ions and manganese ions was 0.25:0.5:0.25 and the total concentration of nickel ions, iron ions and manganese ions was 1 mol / L.
[0051] Prepare a 400 mg / L styrenephosphonic acid solution.
[0052] Prepare a NaOH solution with a concentration of 2 mol / L as a precipitant solution.
[0053] An ammonia solution with a concentration of 0.8 mol / L was prepared as a complexing agent solution.
[0054] Preparation of reactor bottom liquid: The pH value of the reactor bottom liquid is 10.5 and the temperature is 55°C.
[0055] The air in the reactor was evacuated and nitrogen was continuously introduced.
[0056] The mixed salt solution, styrenephosphonic acid solution, precipitant solution and complexing agent solution are simultaneously introduced into the bottom liquid of the reaction kettle and stirred to carry out a coprecipitation reaction. The pH value of the reaction system is controlled to be 10.5, the temperature is 55°C, and the ammonia concentration is 0.5 mol / L; the flow rate of the mixed salt solution is 3 L / h, and the flow rate of the styrenephosphonic acid solution is 10 mL / h.
[0057] When the particle size D50 of the reaction slurry reaches 1.5±0.5 μm, the introduction of the reaction raw materials is stopped and the reaction is stopped.
[0058] The reaction slurry is centrifuged and washed, the solid phase is further washed, and then the solid phase is dried and the iron is sieved out to obtain a precursor.
[0059] Figure 5 This is the SEM image of the precursor obtained in Example 2.
[0060] Example 3 A mixed salt solution was prepared in which the molar ratio of nickel ions to manganese ions was 0.5:0.5 and the total concentration of nickel ions, iron ions and manganese ions was 3 mol / L.
[0061] Prepare a 1000 mg / L styrenephosphonic acid solution.
[0062] Prepare a NaOH solution with a concentration of 5 mol / L as a precipitant solution.
[0063] An ammonia solution with a concentration of 3 mol / L was prepared as a complexing agent solution.
[0064] Preparation of reactor bottom liquid: The pH value of the reactor bottom liquid is 11 and the temperature is 65°C.
[0065] The air in the reactor was evacuated and nitrogen was continuously introduced.
[0066] The mixed salt solution, styrenephosphonic acid solution, precipitant solution and complexing agent solution are simultaneously introduced into the bottom liquid of the reaction kettle and stirred to carry out a coprecipitation reaction. The pH value of the reaction system is controlled to be 11.5, the temperature is 65°C, and the ammonia concentration is 2 mol / L; the flow rate of the mixed salt solution is 5 L / h, and the flow rate of the styrenephosphonic acid solution is 25 mL / h.
[0067] When the particle size D50 of the reaction slurry reaches 3.5±0.5 μm, the introduction of the reaction raw materials is stopped and the reaction is stopped.
[0068] The reaction slurry is centrifuged and washed, the solid phase is further washed, and then the solid phase is dried and sieved to remove iron to obtain a precursor.
[0069] Figure 6 This is the SEM image of the precursor obtained in Example 3.
[0070] The precursors obtained in Examples 1 to 3 and Comparative Example 1 were respectively prepared into positive electrode materials for sodium ion batteries by the following methods: The precursor and sodium carbonate were ground and mixed in a molar ratio of 1:0.525, and then sintered at 900°C in an oxygen atmosphere for 20 hours. After the sintering, the furnace was cooled to room temperature to obtain a sodium ion battery positive electrode material.
[0071] The obtained sodium ion battery positive electrode materials are assembled into batteries in the following ways: The sodium ion battery positive electrode material, acetylene black, and polyvinylidene fluoride were mixed in N-methylpyrrolidone at a mass ratio of 8:1:1 to form a slurry. The slurry was coated on aluminum foil and dried to obtain a positive electrode sheet. With metallic sodium as the negative electrode, sodium electrolyte Whatman GF / D as the diaphragm, and 1M NaClO4in DMC:EC=1:1 Vol% with 5%FEC as the electrolyte, button cells were assembled in a glove box.
[0072] Test the battery cycle performance: Under the conditions of voltage 2~4V and 0.5C, the battery was tested for 50 cycles. The results are as follows Figure 7 shown.
[0073] from Figure 7 It can be seen that when the precursor of the positive electrode material of the sodium ion battery is synthesized by coprecipitation, the addition of styrenephosphonic acid is beneficial to improve the electrical properties of the downstream positive electrode material and the cycle performance of the battery. However, the addition of phosphoric acid / ammonium phosphate has no obvious effect on the improvement of the cycle performance of the battery, and may even have the opposite effect.
[0074] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing a precursor of a sodium ion battery positive electrode material, characterized in that: include: A mixed metal salt solution containing nickel ions, iron ions, and manganese ions, a styrenephosphonic acid solution, a precipitant solution, and a complexing agent solution are simultaneously introduced into the bottom liquid of the reaction kettle to carry out a coprecipitation reaction in a protective atmosphere, and the pH value of the reaction system is controlled to be 11±0.5 and the temperature to be 55-65°C; When the particle size D50 of the reaction slurry reaches the target value, the reaction is stopped; The reaction slurry is subjected to solid-liquid separation, and the solid phase is washed, dried, and sieved to obtain a precursor.
2. The preparation method according to claim 1, characterized in that The molar ratio of nickel ions, iron ions and manganese ions in the mixed metal salt solution is based on the chemical formula Ni x Fe y Mn z (OH)2, wherein 0.25≤x≤0.5, 0≤y≤0.5, 0.25≤z≤0.5, and x+y+z=1; the total concentration of nickel ions, iron ions and manganese ions in the mixed metal salt solution is 1~3 mol / L.
3. The preparation method according to claim 1, characterized in that: The concentration of the styrenephosphonic acid solution is 400-1000 mg / L.
4. The preparation method according to claim 1, characterized in that: The precipitant is at least one of NaOH, KOH, and LiOH; the concentration of the precipitant solution is 2-5 mol / L; the complexing agent solution is a 0.8-3 mol / L ammonia solution; the pH value of the reaction kettle bottom liquid is 10.5-11.0, and the temperature is 55-65°C.
5. The preparation method according to claim 4, characterized in that: During the coprecipitation reaction, the concentration of ammonia in the reaction system is 0.5-2 mol / L.
6. The preparation method according to claim 3, characterized in that: The flow rates of the mixed metal salt solution and the styrenephosphonic acid solution are 3-5 L / h and 10-25 mL / h respectively.
7. The preparation method according to claim 1, characterized in that: The target value of the particle size D50 of the reaction slurry is 1 to 6 microns.
8. A precursor of a sodium ion battery positive electrode material, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 7.
9. A sodium ion battery positive electrode material, characterized in that: The precursor according to claim 8 is mixed with a sodium source and sintered to obtain the product.
10. A sodium ion battery, characterized in that: Comprising the positive electrode material according to claim 9.