Positive electrode precursor material, positive electrode material, preparation method and battery

Abstract

The invention discloses a positive electrode precursor material, a positive electrode material, a preparation method and a battery. The chemical formula of the positive electrode precursor material is (NixFeyMnz) (OH) 2, x is more than 0 and less than or equal to 0.5, y is more than 0, z is more than 0, and x + y + z is equal to 1; the Span of the positive electrode precursor material meets 1.0 lt; a Spanlt; 1.5, wherein Span is equal to (D90-D10) / D50; the peak intensity ratio of the positive electrode precursor material meets (001) / (101) gt; 1. The flaky primary particles of the nickel-iron-manganese ternary precursor material are uniformly distributed in a radial insertion manner, the crystallinity of the material is relatively high, pores are relatively uniform, the embedding of sodium ions is facilitated, and the sintering is promoted; and on the premise that the capacity can meet the requirement, the chemical properties such as long circulation requirement and high rate capability can be met. A continuous method is adopted, continuous production can be achieved, large-scale industrial production is facilitated, and the method has excellent industrial prospects.

Description

Technical Field

[0001] The invention relates to a positive electrode precursor material, a positive electrode material and a preparation method, and a battery. Background Art

[0002] Compared with lithium-ion batteries, sodium-based systems are rich in resources, low in price, environmentally friendly, and have similar electrochemical properties to lithium-ion batteries, especially in terms of rate, low temperature, and safety, and have become a research hotspot for electrochemical energy storage. However, sodium ions have a large ionic radius and slow kinetic rate, which has become the main factor restricting the development of sodium storage materials. Therefore, the preparation of high-performance cathode materials is the key to promoting the application of sodium-ion batteries.

[0003] At present, the mainstream sodium battery materials are mainly layered oxide materials, Prussian blue materials and polyanion materials. Among them, the raw materials of Prussian blue materials are sufficient but contain crystal water that is difficult to remove, and face problems such as poor structural stability; the manufacturing cost of phosphate polyanions is relatively high, and although sulfate polyanion materials have good cycle stability, their energy density is low, which greatly limits their application scenarios; while layered oxide materials have excellent comprehensive performance, and the preparation process is highly similar to the current ternary lithium battery positive electrode, so their development progress is the most advanced. Among them, the most representative nickel-iron-manganese ternary material has relatively mature research and development.

[0004] The performance of positive electrode materials depends largely on the preparation of precursor materials. CN116332247A discloses a nickel-iron-manganese hydroxide positive electrode precursor, which increases the primary particle interlayer spacing through oxidation, while the retained OH can maintain a microscopic layered structure, so that the interplane spacing of the (001) crystal plane is maintained at It helps the subsequent co-firing process with the sodium source and the embedding of sodium ions, which has better performance. However, it also causes the crushing of the primary particles of the secondary balls and the generation of more whiskers that are blocked between the primary particles, and most of the primary particles are in a flat state, thus affecting the electrochemical performance. CN116102078A discloses a method for preparing a high-tap sodium electric precursor, using oxalic acid or oxalate as a complexing agent, and using the strong reducing property of oxalate to inhibit Fe 2+ and Mn 2+ Oxidation change to prevent the formation of Fe 2 (SO 4 ) 3 , Fe 2 O 3 , MnOOH, to obtain a relatively pure substance. Although a high tap density material is prepared, its cycle performance is poor and the cost is high. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies in the structure of the positive electrode precursor material in the prior art, which results in the reduction of electrochemical performance, and to provide a positive electrode precursor material, a positive electrode material, a preparation method, and a battery. The flaky primary particles of the nickel-iron-manganese ternary precursor material of the present invention are evenly distributed in a radial insertion manner, the material has a high crystallinity, and the pores are relatively uniform, which is conducive to the insertion of sodium ions and promotes sintering; under the premise that the capacity can meet the requirements, it also meets the chemical performance requirements such as long cycle life and high rate performance. The present invention adopts a continuous method, which can realize continuous production and is more conducive to large-scale industrial production, and has excellent industrial prospects.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The present invention provides a positive electrode precursor material with the chemical formula (Ni x Fe y Mn z )(OH) 2 , where 0 < x ≤ 0.5, y > 0, z > 0, and x + y + z = 1; the Span of the positive electrode precursor material satisfies 1.0 < Span < 1.5, where Span = (D90 - D10) / D50; the peak intensity ratio of the positive electrode precursor material satisfies (001) / (101) > 1.

[0008] In the present invention, preferably, the Span of the positive electrode precursor material satisfies 1.3 < Span < 1.5.

[0009] In the present invention, preferably, the peak intensity ratio of the positive electrode precursor material satisfies 1 < (001) / (101) < 1.5, for example, 1.3.

[0010] In the present invention, preferably, the positive electrode precursor material is spherical and / or quasi-spherical.

[0011] In the present invention, preferably, the sphericity Q of the positive electrode precursor material satisfies 90% < Q < 100%, for example, 95%.

[0012] In the present invention, preferably, the tap density TD of the positive electrode precursor material is ≥ 1.70 g / cm 3 , for example, 1.89 g / cm 3 .

[0013] In the present invention, preferably, the specific surface area BET of the positive electrode precursor material is 15 - 25 m 2 / g, for example, 19.3 m 2 / g.

[0014] The present invention also provides a method for preparing the above-mentioned cathode precursor material, which comprises the following steps: reacting a mixed solution of a metal salt mixed solution and an ammonia solution in a protective gas, controlling the pH value and ammonia concentration in the mixed solution and maintaining stability, and overflowing to obtain a slurry when the material reaches the target requirements;

[0015] Wherein, the metal salt mixed solution includes an aqueous solution containing a nickel source, an iron source and a manganese source, a complexing agent and an acid; the target requirements include that the Span of the material satisfies 1.0 < Span < 1.5, and the peak intensity ratio satisfies (001) / (101) > 1.

[0016] In the present invention, the nickel source may be selected from one or more of nickel sulfate, nickel chloride and nickel nitrate, such as nickel sulfate.

[0017] In the present invention, the iron source may be selected from one or more of ferrous sulfate, ferrous chloride and ferrous nitrate, such as ferrous sulfate.

[0018] In the present invention, the manganese source may be selected from one or more of manganese sulfate, manganese chloride and manganese nitrate, such as manganese sulfate.

[0019] In the present invention, the molar ratio of the nickel source to the iron source may be (0.5 - 2):1, such as 1:1.

[0020] In the present invention, the molar ratio of the iron source to the manganese source is 1:(0.5 - 2), such as 1:1.

[0021] Preferably, the molar ratio of the nickel source, the iron source and the manganese source is 1:1:1.

[0022] In the present invention, the complexing agent may be selected from one or more of ammonia water, EDTA, EDTA-2Na, citric acid and sodium citrate, such as EDTA-2Na.

[0023] In the present invention, the concentration of the complexing agent may be 1 - 10 g / L, preferably 1 - 3 g / L, such as 2 g / L.

[0024] In the present invention, the acid may be selected from one or more of dilute sulfuric acid, citric acid, oxalic acid and nitric acid, such as dilute sulfuric acid.

[0025] In the present invention, the concentration of the acid may be 1.0 - 5.0 wt%, such as 3.0 - 5.0 wt%, and wt% refers to the mass fraction of the acid in the solution.

[0026] In the present invention, in the metal salt mixed solution, the pH value may be lower than 3.0, such as 2.7 - 3.0.

[0027] In the present invention, in the metal salt mixed solution, the concentration of the metal salt may be 100 - 130 g / L, such as 120 g / L.

[0028] In the present invention, the protective gas is an inert atmosphere. The purity of the protective gas is above 99%.

[0029] In the present invention, the mixed solution may further include a NaOH solution.

[0030] In the present invention, the ammonia concentration of the mixed solution may be 2 - 8 g / L, preferably 3 - 6 g / L, such as 3 g / L.

[0031] In the present invention, the pH value of the mixed solution may be 9 - 12, preferably 9 - 11, such as 10.5 - 11.0.

[0032] In the present invention, the temperature of the reaction may be 30 - 60 °C, such as 35 °C.

[0033] In the present invention, the slurry may also be subjected to post-treatment operations such as aging, centrifugation, washing, and drying.

[0034] Among them, the aging time may be 3 - 5 h, such as 4 h.

[0035] Among them, the drying temperature may be 100 - 140 °C, such as 120 °C.

[0036] Among them, the drying time may be 6 - 12 h, such as 8 h.

[0037] In the present invention, Span is detected during the preparation process, and the materials that meet the target peak intensity ratio are screened by XRD after taking the materials.

[0038] The present invention also provides a method for preparing a cathode material, which is obtained by sintering the above-mentioned cathode precursor material and a sodium source after mixing.

[0039] In the present invention, the sodium source may be selected from one or more of sodium carbonate, sodium bicarbonate, sodium nitrate, sodium acetate, sodium oxalate, sodium hydroxide, and sodium oxide, such as sodium carbonate or sodium hydroxide.

[0040] In the present invention, the sintering temperature may be 800 - 1200 °C, such as 980 °C, 1000 °C, or 1050 °C.

[0041] In the present invention, the sintering time may be 2 - 20 h, such as 10 h.

[0042] The present invention also provides a cathode material, which is obtained by the method for preparing a cathode material described above.

[0043] The present invention also provides a sodium-ion battery, which includes the above-mentioned cathode material.

[0044] On the basis of conforming to the common knowledge in the art, the above preferred conditions can be arbitrarily combined to obtain various preferred embodiments of the present invention.

[0045] The reagents and raw materials used in the present invention are all commercially available.

[0046] The positive and progressive effects of the present invention are as follows:

[0047] The flaky primary particles of the nickel-iron-manganese ternary precursor material of the present invention are evenly distributed in a radial inserted sheet manner, the material has a relatively high crystallinity, and the pores are relatively uniform, which is beneficial to the insertion of sodium ions during the sintering process of the material and promotes sintering; under the premise that the capacity can meet the requirements, it also meets the chemical properties such as long cycle requirements and high rate performance.

[0048] The present invention adopts a continuous method, and realizes the continuous collection of materials by controlling the dynamic balance of the reaction temperature, pH and ammonia value during the reaction process; the target materials are obtained by an overflow method. Compared with the products prepared by the batch method, the primary particles of the nickel-iron-manganese ternary precursor material of the present invention are complete and orderly, have a high sphericity, a high crystallinity, and a large tapped density. Moreover, the preparation method of the present invention can realize continuous production, is more conducive to large-scale industrial production, and has excellent industrial prospects. Description of the Drawings

[0049] Figure 1 XRD pattern of the nickel-iron-manganese ternary precursor prepared in Example 1.

[0050] Figure 2 SEM image of the nickel-iron-manganese ternary precursor prepared in Example 1.

[0051] Figure 3 SEM image of the nickel-iron-manganese ternary precursor prepared in Comparative Example 1. Detailed Embodiments

[0052] The present invention will be further illustrated below by way of examples, but the present invention is not limited to the scope of the described examples. The experimental methods without specific conditions in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0053] Example 1

[0054] (1) Weigh nickel sulfate, ferrous sulfate and manganese sulfate respectively according to a molar ratio of 1:1:1, dissolve them in pure water, add 2 g / L of EDTA-2Na, and adjust the pH of the mixed salt solution to 2.7 - 3.0 with 3 - 5 wt% dilute sulfuric acid. The concentration of the metal salt solution is 120 g / L.

[0055] (2) Add 18 L of pure water to a 25-L reactor and continuously introduce nitrogen (purity above 99%), keep the temperature of the reactor stable at 35 °C, add ammonia water to adjust the ammonia concentration in the bottom liquid to 3.0 g / L, and at this time the pH is between 10.5 and 11.0.

[0056] (3) After the temperature, pH, and ammonia value are stable, pump the mixed salt solution, NaOH solution, and ammonia water into the reactor in parallel at the set flow rates, maintain the temperature of the reactor, automatically control and adjust the flow rates of NaOH and ammonia water through an on-line system, keep the pH stable at around 10.0, and the ammonia concentration at 3.0 g / L. When the particles grow to the target particle size range, at this time the Span is stably maintained between 1.3 and 1.5, start to collect the overflow material, age the slurry (aging time is 4 h), centrifuge, wash, and dry (drying temperature is 120 °C, time is 8 h) to obtain the nickel-iron-manganese ternary precursor.

[0057] (4) Mix the prepared nickel-iron-manganese ternary precursor with sodium carbonate and sinter at 1000 °C for 10 h.

[0058] Comparative Example 1

[0059] (1) Weigh nickel sulfate, ferrous sulfate, and manganese sulfate according to a molar ratio of 1:1:1 respectively, dissolve them in pure water, add 2 g / L of EDTA-2Na, and adjust the pH of the mixed salt solution to 2.7 - 3.0 with 3 - 5% dilute sulfuric acid, and the concentration of the metal salt solution is 120 g / L.

[0060] (2) Add 18 L of pure water to a 25-L reactor and continuously introduce nitrogen, keep the temperature of the reactor stable at 65 °C, add ammonia water to adjust the ammonia concentration in the bottom liquid to 4.0 g / L, and at this time the pH is between 10.5 and 11.0.

[0061] (3) After the temperature, pH, and ammonia value are stable, pump the mixed salt solution, NaOH solution, and ammonia water into the reactor in parallel at the set flow rates, maintain the temperature of the reactor, automatically control and adjust the flow rates of NaOH and ammonia water through an on-line system, keep the pH stable at around 10.5, and the ammonia concentration at 4.0 g / L. When the particles grow to the target particle size range, at this time the Span is stably maintained between 1.0 and 1.2, start to collect the overflow material, age the slurry (aging time is 4 h), centrifuge, wash, and dry (drying temperature is 120 °C, time is 8 h) to obtain the nickel-iron-manganese ternary precursor.

[0062] (4) Mix the prepared nickel-iron-manganese ternary precursor with sodium carbonate and sinter at 1050 °C for 10 h.

[0063] Comparative Example 2

[0064] (1) Weigh nickel sulfate, ferrous sulfate, and manganese sulfate according to a molar ratio of 1:1:1, dissolve them in pure water, add 2 g / L of EDTA-2Na, and adjust the pH of the mixed salt solution to 2.7 - 3.0 with 3 - 5% dilute sulfuric acid. The concentration of the metal salt solution is 120 g / L.

[0065] (2) Add 18 L of pure water to a 25 L reactor and continuously introduce nitrogen. Keep the reactor temperature stable at 40 °C, add ammonia water to adjust the bottom liquid ammonia concentration to 6.0 g / L, and at this time, the pH is between 11.0 - 11.5.

[0066] (3) After the temperature, pH, and ammonia value are stable, pump the mixed salt solution, NaOH solution, and ammonia water into the reactor at a set flow rate in a co-current manner. Maintain the reactor temperature, automatically control and adjust the flow rates of NaOH and ammonia water through an online system, keep the pH stable at around 11.0, and the ammonia concentration at 8.0 g / L. When the particles grow to the target particle size range, and at this time, Span is stably maintained between 1.1 - 1.4, start collecting the overflow material, age the slurry (the aging time is 4 h), centrifuge, wash, and dry (the drying temperature is 120 °C and the time is 8 h) to obtain the nickel-iron-manganese ternary precursor.

[0067] (4) Mix the prepared nickel-iron-manganese ternary precursor with sodium carbonate and sinter it at 1000 °C for 10 h.

[0068] Comparative Example 3

[0069] (1) Weigh nickel sulfate, ferrous sulfate, and manganese sulfate according to a molar ratio of 1:1:1, dissolve them in pure water, add 2 g / L of EDTA-2Na, and adjust the pH of the mixed salt solution to 2.7 - 3.0 with 3 - 5% dilute sulfuric acid. The concentration of the metal salt solution is 120 g / L.

[0070] (2) Add 18 L of pure water to a 25 L reactor and continuously introduce nitrogen. Keep the reactor temperature stable at 50 °C, add ammonia water to adjust the bottom liquid ammonia concentration to 5.0 g / L, and at this time, the pH is between 10.5 - 11.0.

[0071] (3) After the temperature, pH, and ammonia value are stable, pump the mixed salt solution, NaOH solution, and ammonia water into the reactor at a set flow rate in a co-current manner. Maintain the reactor temperature, automatically control and adjust the flow rates of NaOH and ammonia water through an online system, keep the pH stable at around 11.5, and the ammonia concentration at 5.0 g / L. When the particles grow to the target particle size range, and at this time, Span is stably maintained between 1.3 - 1.5, start collecting the overflow material, age the slurry (the aging time is 4 h), centrifuge, wash, and dry (the drying temperature is 120 °C and the time is 8 h) to obtain the nickel-iron-manganese ternary precursor.

[0072] (4) Mix the prepared nickel-iron-manganese ternary precursor with sodium carbonate and sinter at 980 °C for 10 h.

[0073] Effect Example 1 Morphology and Structure

[0074] Perform the following tests on the nickel-iron-manganese ternary precursors prepared in the above examples and comparative examples:

[0075] (1) Morphology: Characterized by SEM.

[0076] (2) Span (Span = (D90 - D10) / D50): Tested by a Malvern 3000 particle size analyzer.

[0077] (3) (001) / (101) peak intensity ratio: The crystallinity is measured by XRD characterization.

[0078] (4) Tap density TD: Tested using an AUTOTAP tapped density analyzer.

[0079] (5) Specific surface area BET: Tested using a Micromeritics 3030 automatic specific surface area and porosity analyzer.

[0080] (6) Sphericity Q: The sphericity of the powder is tested using a Malvern FPIA3000 particle analyzer. Dry method testing, CCD magnification: 10 times, timing counting method, bright light source detection. The sphericity Q is obtained by calculating the projection of the particles: Q = 4π*S / (L2)*100%, where S is the projected area of the secondary sphere of the precursor and L is the projected perimeter of the secondary sphere of the precursor.

[0081] The results are shown in Table 1, Figures 1-3 as shown.

[0082] According to Figure 2 and 3 it can be seen that the primary particles of the nickel-iron-manganese ternary precursor prepared in Example 1 are uniform.

[0083] Effect Example 2 Electrochemical Performance

[0084] 1. Assemble the cathode materials prepared in the above examples and comparative examples into batteries:

[0085] Dissolve the above cathode material, acetylene black, and polyvinylidene fluoride in N-methyl-2-pyrrolidone according to a mass ratio of 93:4:3, fully slurry to prepare a solution, and then evenly coat it on an aluminum foil, dry and stamp it into a thin sheet. Assemble the battery electrode sheet (thin sheet), sodium metal sheet, glass fiber separator, electrolyte (NaClO 4 ) gasket, spring piece, and battery case into a small soft package in an Ar gas glove box, and perform performance tests on the battery.

[0086] 2. Detection method:

[0087] (1) Capacity test: Test the charge and discharge capacity at 0.33C between 1.5 - 4.0V.

[0088] (2) Rate performance: Test the discharge capacity at 0.33C / 3C between 1.5 - 4.0V respectively.

[0089] (3) Cycle performance: Test at 0.5C / 1C 100% DOD cycle@25℃ between 1.5 - 4.0V for 200 cycles.

[0090] (4) Storage gas generation test: At 25℃, charge to 4.0V at 0.063A / g (calculated based on the mass m0 of the positive electrode material). Using the water displacement method, record the initial volume V0 of the battery. Then store the battery in a 60℃ constant temperature oven. Every 7 days, take the battery out of the oven, let it stand until room temperature, test the volume of the battery, and then charge the battery to 4.0V at 0.063A / g again. The volume change of the battery corresponds to the amount of gas generated by the battery cell. The gas generation amount on the 21st day is the final gas generation amount of the battery pack.

[0091] The results are shown in Table 2.

[0092] Table 1

[0093]

[0094] Table 2

[0095]

[0096] It can be seen that the capacity, rate performance, cycle performance, and gas generation of Example 1 are all superior to those of Comparative Examples 1 - 3. It is speculated that this is because in the positive electrode precursor material prepared in Example 1, (001) / (101)>1, the (001) plane is more exposed, and the crystallinity is higher, which is beneficial to the cycle performance of the material; moreover, the primary particles are well-developed, and the distribution of the primary particle inserts (as Figure 2 shown) is beneficial to the insertion of sodium ions during subsequent sintering (i.e., beneficial to sintering), further improving the specific capacity, rate performance, and gas generation of the battery.

Claims

1. A cathode precursor material, characterized in that, Its chemical formula is (Ni x Fe y Mn z )(OH) 2 , where 0 < x ≤ 0.5, y > 0, z > 0, and x + y + z = 1; the Span of the positive electrode precursor material satisfies 1.0 < Span < 1.5, where Span = (D90 - D10) / D50; the peak intensity ratio of the positive electrode precursor material satisfies (001) / (101) > 1.

2. The cathode precursor material according to claim 1, characterized in that, the cathode precursor material satisfies one or more of the following conditions: a. The Span of the cathode precursor material satisfies 1.3 < Span < 1.5; b. The peak intensity ratio of the cathode precursor material satisfies 1 < (001) / (101) < 1.

5.

3. The cathode precursor material according to claim 2, characterized in that, the cathode precursor material satisfies one or more of the following conditions: a. The cathode precursor material is spherical and / or quasi-spherical; b. The sphericity Q of the cathode precursor material satisfies 90% < Q < 100%; c. The tap density TD of the positive electrode precursor material ≥ 1.70 g / cm 3 ; d. The specific surface area BET of the positive electrode precursor material is 15 - 25 m 2 / g.

4. A method for preparing the cathode precursor material according to any one of claims 1-3, characterized in that, it includes the following steps: In a protective gas, react a mixed solution of a metal salt mixed solution and an ammonia solution, control the pH value and ammonia concentration in the mixed solution and maintain stability. When the material reaches the target requirements, overflow to obtain a slurry; wherein, the metal salt mixed solution includes an aqueous solution containing a nickel source, an iron source and a manganese source, a complexing agent and an acid; the target requirements include that the Span of the material satisfies 1.0 < Span < 1.5 and the peak intensity ratio satisfies (001) / (101) > 1.

5. The method for preparing the cathode precursor material according to claim 4, characterized in that, the preparation method satisfies one or more of the following conditions: a. The nickel source is selected from one or more of nickel sulfate, nickel chloride and nickel nitrate; b. The iron source is selected from one or more of ferrous sulfate, ferrous chloride and ferrous nitrate; c. The manganese source is selected from one or more of manganese sulfate, manganese chloride and manganese nitrate; d. The molar ratio of the nickel source to the iron source is (0.5-2):1; e. The molar ratio of the iron source to the manganese source is 1:(0.5-2); f. The complexing agent is selected from one or more of ammonia water, EDTA, EDTA-2Na, citric acid and sodium citrate; g. The concentration of the complexing agent is 1-10 g / L; h. The acid is selected from one or more of dilute sulfuric acid, citric acid, oxalic acid and nitric acid; i. The concentration of the acid is 1.0-5.0 wt%, and wt% refers to the mass fraction of the acid in the solution; j. In the metal salt mixed solution, the pH value is lower than 3.0; k. In the metal salt mixed solution, the concentration of the metal salt is 100-130 g / L; l. The protective gas is an inert atmosphere; m. In the mixed solution, a NaOH solution is further included; n. The ammonia concentration of the mixed solution is 2-8 g / L; o. The pH value of the mixed solution is 9-12; p. The temperature of the reaction is 30-60 °C; q. The slurry also undergoes post-treatment operations such as aging, centrifugation, washing and drying.

6. The method for preparing the cathode precursor material according to claim 5, characterized in that, the preparation method satisfies one or more of the following conditions: a. The nickel source is nickel sulfate; b. The iron source is ferrous sulfate; c. The manganese source is manganese sulfate; d. The complexing agent is EDTA-2Na; e. The concentration of the complexing agent is 1-3 g / L; f. The acid is dilute sulfuric acid; g. The purity of the protective gas is above 99%; h. The ammonia concentration of the mixed solution is 3-6 g / L; i. The pH value of the mixed solution is 9-11.

7. A method for preparing a cathode material, characterized in that, it is prepared by mixing the cathode precursor material according to any one of claims 1-3 with a sodium source and then sintering.

8. The method for preparing a cathode material according to claim 7, characterized in that, the preparation method satisfies one or more of the following conditions: a. The sodium source is selected from one or more of sodium carbonate, sodium bicarbonate, sodium nitrate, sodium acetate, sodium oxalate, sodium hydroxide and sodium oxide; b. The sintering temperature is 800-1200 °C; c. The sintering time is 2-20 h.

9. A cathode material, characterized in that, it is prepared by the method for preparing a cathode material according to claim 7 or 8.

10. A sodium ion battery, characterized in that, it includes the cathode material according to claim 9.

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