Preparation method of sodium-nickel fluoride battery positive electrode material, positive electrode material and battery
Sodium-nickel fluoride battery cathode materials were prepared by co-precipitation method. By controlling pH value and temperature, the internal resistance problem of sodium-nickel chloride batteries during high-rate discharge was solved, and the high-rate discharge capability and cycle stability of the batteries were improved.
Patent Information
- Application Number
- CN202511279241.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-08
- Publication Date
- 2026-01-27
AI Technical Summary
Existing sodium-nickel chloride batteries have high internal resistance at high discharge rates, posing safety hazards. Furthermore, nickel chloride is prone to decomposition under certain conditions, and there is a lack of effective preparation methods and performance optimization strategies.
Sodium-nickel fluoride battery cathode materials were prepared by co-precipitation. The co-precipitation reaction was carried out by controlling the pH value and temperature within the range of 40-60℃, followed by sintering in a nitrogen atmosphere to optimize the material structure and reduce internal resistance.
It significantly reduces internal resistance, improves the high-rate discharge capability and cycle stability of sodium-nickel fluoride batteries, and exhibits good high-rate discharge performance and excellent cycle life.
Abstract
Description
Technical Field
[0001] This invention relates to the field of sodium-ion battery technology, and in particular to a method for preparing a sodium-nickel fluoride battery cathode material, as well as the cathode material, battery cathode, and battery. Background Technology
[0002] With the in-depth research of new energy technologies, the continuous advancement of industrialization, and the rapid development of the social economy, problems such as the depletion of oil resources, global warming, and environmental pollution are troubling modern society. People urgently seek new clean and renewable energy sources and energy storage materials and devices. Against this backdrop, lithium-ion batteries, with their high energy density, small size, and long cycle life, have developed rapidly and shown great application potential. However, the relatively scarce and unevenly distributed lithium resources have significantly increased the cost of lithium-ion battery production, which is detrimental to the continued widespread use of lithium batteries. In contrast, sodium resources are abundant, and their physicochemical properties are similar to lithium. Therefore, developing high-performance sodium-ion batteries is of great significance for the vigorous development of clean energy.
[0003] The sodium-nickel chloride battery (also known as the Zebra battery), developed from the sodium-sulfur battery, possesses advantages similar to sodium-sulfur batteries, including high theoretical specific capacity, good cycle performance, long lifespan, and no self-discharge. However, its safety performance is far superior. The positive electrode of the sodium-nickel chloride battery contains a molten salt electrolyte, NaAlCl4. Even under the most severe conditions (ceramic membrane rupture, direct contact between the positive and negative electrodes), NaAlCl4 preferentially reacts with sodium to form sodium chloride and aluminum. This reaction is mild and non-explosive, and a passivation film forms on the sodium surface, preventing further reaction. In contrast, the sodium-sulfur battery will explode under the same conditions (molten sulfur at the positive electrode directly contacting molten sodium at the negative electrode), which is extremely dangerous. Furthermore, this battery is assembled in a discharged state, requiring only a very small amount of sodium at the negative electrode to maintain initial current collection. These factors contribute to the superior safety of the sodium-nickel chloride battery. Based on these advantages, research on sodium-nickel chloride batteries is increasingly focused on, making it an important option for high-capacity energy storage.
[0004] However, sodium-nickel chloride batteries exhibit high internal resistance at high discharge rates, limiting their practical applications. Nickel chloride is prone to decomposition under certain operating conditions, posing certain safety hazards. Furthermore, current technologies have not fully explored the potential of nickel fluoride as a cathode material for sodium-ion batteries, lacking effective preparation methods and performance optimization strategies. Summary of the Invention
[0005] In view of this, the present invention provides a method for preparing a sodium-nickel fluoride battery cathode material, as well as the cathode material, the battery cathode, and the battery. By designing a new preparation process, the high internal resistance and safety hazards existing in the prior art are solved, ensuring that the battery maintains excellent performance even at high discharge rates.
[0006] The first aspect of this invention provides a method for preparing a sodium-nickel fluoride battery cathode material, comprising:
[0007] (1) In the presence of a precipitant, nickel fluoride and sodium source are co-precipitated in a solvent to obtain a precipitate; wherein the amount of the precipitant is such that the pH value of the coprecipitation reaction is 7-9; and the temperature of the coprecipitation reaction is 40-60℃.
[0008] (2) After drying the precipitate, it is sintered in a nitrogen atmosphere to obtain the sodium-nickel fluoride battery cathode material.
[0009] In this invention, nickel fluoride and sodium source are selected as the main raw materials, preferably with a nickel fluoride purity greater than 95% to ensure battery performance. Nickel fluoride and sodium source are mixed in a certain proportion, and a precursor is prepared by co-precipitation. By controlling the reaction temperature and pH value, a uniform precipitate is formed to ensure sufficient reaction between sodium and nickel fluoride. Preferably, the pH value of the co-precipitation reaction is 7.5-8.5, and the temperature is 45-55℃. The precipitate is dried at a specific temperature and then sintered in a nitrogen atmosphere for a certain time to promote phase transformation and improve conductivity.
[0010] In this invention, the sodium source can be a sodium-containing compound commonly used in the art, preferably including at least one of sodium carbonate, sodium acetate, sodium nitrite, sodium sulfate, sodium oxalate, sodium persulfate, sodium hydroxide, sodium pyrosulfate, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium metabisulfite, sodium pyrophosphate, sodium hydrogen phthalate, sodium bioxalate, sodium sulfite, sodium sorbate, trisodium phosphate, sodium gluconate, sodium oleate, and hydrates of the above substances. Most preferably, sodium carbonate is used as the sodium source.
[0011] Preferably, the precipitant is selected from at least one of ammonia, sodium hydroxide, and potassium hydroxide. The concentration of the precipitant can be adjusted as needed, preferably 0.1-1 mol / L.
[0012] Preferably, the mass ratio of nickel fluoride to the sodium source is (0.8-1.2):1.
[0013] Preferably, in step (2), the drying conditions include: a drying temperature of 60-80℃ and a drying time of 12-48h.
[0014] Preferably, the sintering conditions include: a sintering temperature of 500-700℃ and a sintering time of 2-5 hours.
[0015] A second aspect of the present invention provides a sodium-nickel fluoride battery cathode material, wherein the battery cathode material is a battery cathode material obtained by the aforementioned preparation method.
[0016] A third aspect of the present invention provides a sodium-nickel fluoride battery positive electrode, wherein the positive electrode material sequentially comprises a current collector and a positive electrode material coating formed by a positive electrode material slurry; wherein the positive electrode material slurry comprises the battery positive electrode material, a conductive agent, and a binder as described above, wherein, based on the total weight of the positive electrode material slurry, the content of the positive electrode material is 80-90 wt%, the content of the conductive agent is 5-10 wt%, and the content of the binder is 5-10 wt%.
[0017] In this invention, the current collector can be aluminum foil. Preferably, the conductive agent is selected from at least one of conductive carbon black, acetylene black, carbon nanotubes, graphene, and conductive graphite. Preferably, the binder is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), and polyacrylic acid (PAA).
[0018] According to a preferred embodiment of the present invention, the synthesized positive electrode material and conductive carbon black are mixed by a coating method and then coated onto a conductive substrate by a polymer binder to ensure the conductivity and mechanical strength of the electrode.
[0019] A fourth aspect of the present invention provides a sodium-nickel fluoride battery, comprising a positive electrode, a sodium metal negative electrode, and an electrolyte as described above.
[0020] Preferably, the electrolyte is a sodium chloride (NaCl) solution and / or a sodium fluoride (NaF) solution. More preferably, the solvent of the electrolyte is water or a carbonate. Preferably, the carbonate is selected from dimethyl carbonate, ethylene carbonate, methyl trifluoromethanesulfonate, and propylene carbonate. The concentration of the electrolyte is 0.5-2 mol / L, preferably 1-2 mol / L. In this invention, by selecting a suitable electrolyte for sodium-nickel fluoride batteries and optimizing the salt concentration and solvent, the ionic conductivity can be further improved and the internal resistance of the battery can be reduced.
[0021] Assemble the battery in a dry nitrogen environment to ensure full contact between the electrolyte and electrode materials and prevent moisture from affecting battery performance.
[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0023] This invention significantly reduces internal resistance and improves rate performance by optimizing the preparation process of the cathode material for sodium-nickel fluoride batteries, enabling stable operation in high-power applications. Compared with existing sodium-nickel chloride batteries, it exhibits excellent high-rate discharge capability and superior cycle stability. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0025] In the embodiments provided in this specification, unless specific techniques or conditions are specified, the techniques or conditions described in the literature in this field, or the product instructions, shall be followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased from legitimate channels.
[0026] Example 1
[0027] (1) Add 5g of nickel fluoride powder to a 500mL beaker, add 300mL of deionized water, heat to 50℃ and stir for 30 minutes, then add 5mL of ammonia (1mol / L) to completely dissolve the nickel fluoride. Prepare 100mL of 0.5mol / L Na2CO3 solution and slowly add it dropwise at a rate of 2mL per minute while stirring. After the addition is complete, continue stirring and react for 60 minutes. The temperature during the reaction is 50℃ and the pH is 8. Cool to room temperature, filter to separate the precipitate, and wash with deionized water.
[0028] (2) The precipitate was dried at 60°C for 12 hours, and then sintered at 500°C in a nitrogen atmosphere for 2 hours to obtain the positive electrode material. The tensile strength of the electrode material was 30 MPa after tensile strength testing.
[0029] (3) The prepared positive electrode material is mixed with conductive carbon black and coated on aluminum foil using a polymer polyvinylidene fluoride (PVDF) binder to prepare the battery positive electrode. The mass ratio of the positive electrode material, conductive carbon black and binder is 8:1:1.
[0030] (4) The prepared battery positive electrode was combined with a sodium metal negative electrode, and charge-discharge tests were conducted using an electrolyte (sodium chloride (NaCl) aqueous solution, concentration 1 mol / L). The test conditions were: room temperature, charge-discharge current of 0.5C, discharge cut-off voltage of 1.5V, and charge cut-off voltage of 3.0V. The test results showed that the sodium-nickel fluoride battery had an internal resistance of only 0.5Ω at a rate of 2C, an initial discharge specific capacity of 120mAh / g, and a charge-discharge efficiency of 98%. After 500 cycles, the capacity retention rate was 85%, demonstrating good high-rate discharge capability and excellent cycle stability.
[0031] Example 2
[0032] Sodium-nickel fluoride batteries were prepared and assembled according to the method of Example 1, except that the temperature of the co-precipitation reaction in step 1 was 40°C. Tensile strength testing showed that the electrode material had a tensile strength of 29 MPa. Charge-discharge tests were conducted according to the method of Example 1. The results showed that the sodium-nickel fluoride battery, at a rate of 2C, had an internal resistance of 0.7 Ω, an initial discharge specific capacity of 114 mAh / g, and a charge-discharge efficiency of 95%. After 500 cycles, the capacity retention was 81%.
[0033] Example 3
[0034] Sodium-nickel fluoride batteries were prepared and assembled according to the method of Example 1, with the only difference being that the pH of the co-precipitation reaction in step 1 was 7. Tensile strength testing showed that the electrode material had a tensile strength of 27 MPa. Charge-discharge tests were conducted according to the method of Example 1. The results showed that the sodium-nickel fluoride battery, at a 2C rate, had an internal resistance of 0.8 Ω, an initial discharge specific capacity of 116 mAh / g, and a charge-discharge efficiency of 96%. After 500 cycles, the capacity retention was 84%.
[0035] Example 4
[0036] Sodium-nickel fluoride batteries were prepared and assembled according to the method of Example 1, with the only difference being that the mass ratio of nickel fluoride to sodium source in step 1 was 0.8:1. Tensile strength testing showed that the electrode material had a tensile strength of 28 MPa. Charge-discharge tests were conducted according to the method of Example 1. The results showed that the sodium-nickel fluoride battery, at a 2C rate, had an internal resistance of 0.7 Ω, an initial discharge specific capacity of 117 mAh / g, and a charge-discharge efficiency of 95%. After 500 cycles, the capacity retention was 82%.
[0037] Example 5
[0038] Sodium-nickel fluoride batteries were prepared and assembled according to the method of Example 1, with the only difference being that the sintering temperature in step 2 was 600°C. Tensile strength testing showed that the electrode material had a tensile strength of 27.5 MPa. Charge-discharge tests were conducted according to the method of Example 1. The results showed that the sodium-nickel fluoride battery, at a 2C rate, had an internal resistance of 0.6 Ω, an initial discharge specific capacity of 112 mAh / g, and a charge-discharge efficiency of 93%. After 500 cycles, the capacity retention was 79%.
[0039] Example 6
[0040] Sodium-nickel fluoride batteries were prepared and assembled according to the method of Example 1, with the only difference being that the sintering time in step 2 was 5 hours. Tensile strength testing showed that the electrode material had a tensile strength of 28.6 MPa. Charge-discharge tests were conducted according to the method of Example 1. The results showed that the sodium-nickel fluoride battery, at a 2C rate, had an internal resistance of 0.65 Ω, an initial discharge specific capacity of 113 mAh / g, and a charge-discharge efficiency of 91%. After 500 cycles, the capacity retention was 80%.
[0041] Example 7
[0042] Sodium-nickel fluoride batteries were prepared and assembled according to the method of Example 1, with the only difference being that the electrolyte in step 4 was an aqueous sodium fluoride solution. Tensile strength testing showed that the electrode material had a tensile strength of 26.8 MPa. Charge-discharge tests were conducted according to the method of Example 1. The results showed that the sodium-nickel fluoride battery, at a 2C rate, had an internal resistance of 0.8 Ω, an initial discharge specific capacity of 111 mAh / g, and a charge-discharge efficiency of 90%. After 500 cycles, the capacity retention was 78%.
[0043] Comparative Example 1
[0044] Sodium-nickel fluoride batteries were prepared and assembled according to the method of Example 1, except that in step (2), the precipitate was dried at 60°C for 12 hours to obtain the positive electrode material, and the heating step in a nitrogen atmosphere was omitted. Tensile strength testing showed that the electrode material had a tensile strength of 6.1 MPa. Charge-discharge tests were performed according to the method of Example 1. The results showed that the sodium-nickel fluoride battery had an internal resistance of 10.5 Ω, an initial discharge specific capacity of 60 mAh / g, and a charge-discharge efficiency of 65% at a 2C rate. After 500 cycles, the capacity retention was 36%. Its high-rate discharge capability and cycle stability were significantly inferior to those of Example 1.
[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a sodium-nickel fluoride battery cathode material, characterized in that, include: (1) In the presence of a precipitant, nickel fluoride and sodium source are co-precipitated in a solvent to obtain a precipitate; wherein the amount of the precipitant is such that the pH value of the coprecipitation reaction is 7-9; and the temperature of the coprecipitation reaction is 40-60℃. (2) After drying the precipitate, it is sintered in a nitrogen atmosphere to obtain the sodium-nickel fluoride battery cathode material.
2. The preparation method according to claim 1, characterized in that, The sodium source is selected from at least one of sodium carbonate, sodium acetate, sodium nitrite, sodium sulfate, sodium oxalate, sodium persulfate, sodium hydroxide, sodium pyrosulfate, sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium metabisulfite, sodium pyrophosphate, sodium hydrogen phthalate, sodium hydrogen oxalate, sodium sulfite, sodium sorbate, trisodium phosphate, sodium gluconate, sodium oleate, and hydrates of the above substances. Preferably, the precipitant is selected from at least one of ammonia, sodium hydroxide, and potassium hydroxide.
3. The preparation method according to claim 1, characterized in that, The mass ratio of nickel fluoride to the sodium source is (0.8-1.2):
1.
4. The preparation method according to claim 1, wherein, The drying conditions include: a drying temperature of 60-80℃ and a drying time of 12-48h; Preferably, the sintering conditions include: a sintering temperature of 500-700℃ and a sintering time of 2-5 hours.
5. A sodium-nickel fluoride battery cathode material, characterized in that, The battery cathode material is a battery cathode material obtained by any one of the preparation methods in claims 1-4.
6. A sodium-nickel fluoride battery positive electrode, characterized in that, The positive electrode material sequentially comprises a current collector and a positive electrode material coating formed by a positive electrode material slurry; wherein the positive electrode material slurry comprises the battery positive electrode material as described in claim 5, a conductive agent, and a binder, wherein, based on the total weight of the positive electrode material slurry, the content of the positive electrode material is 80-90 wt%, the content of the conductive agent is 5-10 wt%, and the content of the binder is 5-10 wt%.
7. The positive electrode of the battery according to claim 6, characterized in that, The conductive agent is selected from at least one of conductive carbon black, acetylene black, carbon nanotubes, graphene, and conductive graphite; the binder is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, carboxymethyl cellulose, and polyacrylic acid (PAA).
8. A sodium-nickel fluoride battery, characterized in that, It includes the battery positive electrode, sodium metal negative electrode, and electrolyte as described in claim 6 or 7.
9. The battery according to claim 8, characterized in that, The electrolyte is a sodium chloride solution and / or a sodium fluoride solution.
10. The battery according to claim 8, characterized in that, The electrolyte is a solvent of water or carbonate, and the concentration of the electrolyte is 0.5-2 mol / L.