A nickel-iron-manganese-copper precursor, its preparation method and application

Abstract

The present disclosure relates to a nickel-iron-manganese-copper precursor, a preparation method thereof, and an application thereof, belonging to the field of battery technology. The molecular formula of the nickel-iron-manganese-copper precursor is Ni a Fe b Mn c Cu d (OH)2, where 0.1 ≤ a ≤ 0.8, 0.1 ≤ b ≤ 0.8, 0.1 ≤ c ≤ 0.8, 0.02 ≤ d ≤ 0.5, and a + b + c + d = 1; the nickel-iron-manganese-copper precursor is granular, with a sulfur content not exceeding 1200 ppm; and its specific surface area does not exceed 50 m 2 / g, and its tapped density is not less than 1.25 g / cm 3 . The preparation of the precursor includes: mixing an intermediate precursor with an antioxidant, a complexing agent, and a precipitating agent to perform deep coprecipitation and preliminary desulfurization treatment; the intermediate precursor is obtained by preliminary coprecipitation of a nickel-iron-manganese-copper mixed metal sulfate solution and a precipitating agent according to the preset molecular formula of the precursor. The method is simple to operate and can obtain a nickel-iron-manganese-copper precursor with a low sulfur content and good particle morphology. The precursor can be further used to prepare a cathode material and a battery.

Description

Technical Field

[0001] The present disclosure relates to the technical field of batteries, and in particular, to a nickel-iron-manganese-copper precursor, a preparation method and an application thereof. Background Art

[0002] Nickel-iron-manganese-copper hydroxide is a cathode precursor for sodium-ion batteries. It is usually prepared by co-precipitation of a nickel-iron-manganese-copper mixed metal sulfate solution and a precipitant. However, during the co-precipitation preparation process, copper hydroxide belongs to the orthorhombic system and is incompatible with the trigonal system to which nickel-iron-manganese ternary hydroxide belongs. At the same time, copper hydroxide is easily decomposed into copper oxide at 50 °C, which further destroys the structural consistency of the precursor. Therefore, the nickel-iron-manganese-copper hydroxide prepared by this method has many lattice defects, poor morphology, and high impurity content (especially the high sulfur content brought by sulfate in the raw materials), which will affect the performance of the subsequent cathode material.

[0003] In view of this, the present disclosure is specifically proposed. Summary of the Invention

[0004] One of the purposes of the present disclosure is to provide a nickel-iron-manganese-copper precursor with low sulfur content and good particle morphology.

[0005] Another purpose of the present disclosure is to provide a preparation method of the above nickel-iron-manganese-copper precursor.

[0006] Another purpose of the present disclosure is to provide a cathode material further prepared from the above nickel-iron-manganese-copper precursor.

[0007] Another purpose of the present disclosure is to provide a battery further prepared from the above cathode material.

[0008] The present disclosure can be implemented as follows:

[0009] In a first aspect, the present disclosure provides a nickel-iron-manganese-copper precursor with the molecular formula Ni a Fe b Mn c Cu d (OH) 2 , where 0.1 ≤ a ≤ 0.8, 0.1 ≤ b ≤ 0.8, 0.1 ≤ c ≤ 0.8, 0.02 ≤ d ≤ 0.5, and a + b + c + d = 1;

[0010] The nickel-iron-manganese-copper precursor is in a granular shape and the sulfur content does not exceed 1200 ppm;

[0011] And the nickel-iron-manganese-copper precursor further has the following:

[0012] Feature 1: The specific surface area of the nickel-iron-manganese-copper precursor does not exceed 50 m 2 / g;

[0013] Feature 2: The tap density of the nickel-iron-manganese-copper precursor is not less than 1.25 g / cm 3 .

[0014] In an optional embodiment, the nickel-iron-manganese-copper precursor further has at least one of the following features:

[0015] Feature 3: The D 10 of the nickel-iron-manganese-copper precursor is not less than 4 μm;

[0016] Feature 4: The D 50 of the nickel-iron-manganese-copper precursor is not less than 9 μm;

[0017] Feature 5: The D 90 of the nickel-iron-manganese-copper precursor is not higher than 27 μm.

[0018] In an optional embodiment, the nickel-iron-manganese-copper precursor is in the form of complete particles;

[0019] and / or, the sulfur content of the nickel-iron-manganese-copper precursor is 792 - 929 ppm;

[0020] and / or, the specific surface area of the nickel-iron-manganese-copper precursor is 34.2 - 41.5 m 2 / g;

[0021] and / or, the tap density of the nickel-iron-manganese-copper precursor is 1.26 - 1.42 g / cm 3 ;

[0022] and / or, the D 10 of the nickel-iron-manganese-copper precursor is 5.22 - 6.07 μm;

[0023] and / or, the D 50 of the nickel-iron-manganese-copper precursor is 9.42 - 11.27 μm;

[0024] and / or, the D 90 of the nickel-iron-manganese-copper precursor is 19.73 - 24.86 μm.

[0025] In a second aspect, the present disclosure provides a method for preparing a nickel-iron-manganese-copper precursor as in any one of the foregoing embodiments, comprising the following steps: mixing an intermediate precursor with an antioxidant, a complexing agent, and a precipitating agent to perform deep coprecipitation and preliminary desulfurization treatment;

[0026] wherein, the intermediate precursor is obtained by preliminary coprecipitation of a nickel-iron-manganese-copper mixed metal sulfate solution and a precipitating agent according to a preset molecular formula of the nickel-iron-manganese-copper precursor.

[0027] In an optional embodiment, the precipitating agent includes a sodium hydroxide solution.

[0028] In an alternative embodiment, a complexing agent is further added during the preliminary coprecipitation process.

[0029] In an alternative embodiment, the complexing agent includes at least one of ammonia water, sodium citrate, ammonium citrate, EDTA, and sodium oxalate.

[0030] In an alternative embodiment, the reaction temperature of the preliminary coprecipitation is 30 - 85 °C; and / or, the reaction pH value is 8 - 11.

[0031] In an alternative embodiment, the preliminary coprecipitation is carried out under stirring conditions.

[0032] In an alternative embodiment, the stirring speed is 200 - 500 rpm.

[0033] In an alternative embodiment, a protective gas is introduced during the preliminary coprecipitation process.

[0034] In an alternative embodiment, the protective gas includes an inert gas.

[0035] In an alternative embodiment, the antioxidant includes at least one of ascorbic acid, sodium erythorbate, vitamin E, carotenoid, and anthocyanin.

[0036] In an alternative embodiment, the addition amount of the antioxidant is 0.001 - 0.1 mol / L.

[0037] In an alternative embodiment, the complexing agent used in the deep coprecipitation and preliminary desulfurization treatment process includes at least one of ammonia water, ammonium citrate, sodium citrate, EDTA, and sodium oxalate.

[0038] In an alternative embodiment, the addition amount of the complexing agent in the deep coprecipitation and preliminary desulfurization treatment process is 0.01 - 0.5 mol / L.

[0039] In an alternative embodiment, the precipitating agent used in the deep coprecipitation and preliminary desulfurization treatment process includes a sodium hydroxide solution.

[0040] In an alternative embodiment, the concentration of the precipitating agent used in the deep coprecipitation and preliminary desulfurization treatment process is 5 - 10 mol / L, and the addition time is 0.5 - 2 h.

[0041] In an alternative embodiment, the temperature of the deep coprecipitation and preliminary desulfurization treatment process is 50 - 80 °C.

[0042] In an alternative embodiment, during the deep coprecipitation and preliminary desulfurization treatment process, when the pH value of the deep coprecipitation system is 10 - 13, the feeding is stopped.

[0043] In an alternative embodiment, the deep coprecipitation and preliminary desulfurization treatment is carried out under stirring conditions.

[0044] In an alternative embodiment, the stirring speed during the deep coprecipitation and preliminary desulfurization treatment is 100 - 500 rpm.

[0045] In an alternative embodiment, it further includes deeply desulfurizing the material obtained from the deep coprecipitation and preliminary desulfurization treatment.

[0046] In an alternative embodiment, the deep desulfurization includes: dehydrating the material and rinsing the dehydrated solid with a desulfurization solution.

[0047] In an alternative embodiment, the desulfurization solution includes a sodium hydroxide solution.

[0048] In an alternative embodiment, the concentration of the sodium hydroxide solution as the desulfurization solution is 0.6 - 1.8 mol / L.

[0049] In an alternative embodiment, the desulfurization solution further contains a complexing agent.

[0050] In an alternative embodiment, the complexing agent contained in the desulfurization solution includes at least one of ammonia water, sodium citrate, ammonium citrate, EDTA, and sodium oxalate.

[0051] In an alternative embodiment, the concentration of the complexing agent contained in the desulfurization solution is 0.01 - 0.5 mol / L.

[0052] In an alternative embodiment, the solid after being rinsed with the desulfurization solution is washed with water and then dried.

[0053] In a third aspect, the present disclosure provides a cathode material, and the raw materials for its preparation include the nickel - iron - manganese - copper precursor of any one of the foregoing embodiments.

[0054] In a fourth aspect, the present disclosure provides a battery, which contains the cathode material of the foregoing embodiment.

[0055] The beneficial effects of the present disclosure include:

[0056] The precursor provided by the present disclosure has a low sulfur content and good particle morphology, and can be further used to prepare a cathode material and a battery, which is conducive to obtaining better electrochemical performance.

[0057] The preparation method of the foregoing precursor provided by the present disclosure is simple in operation. By performing deep coprecipitation on the intermediate precursor, the complexing agent and antioxidant added during this process can protect the particles. By slowly adding the precipitating agent, it can preliminarily desulfurize by replacing sulfate radicals while preventing particle damage caused by violent reactions, thereby keeping the particle morphology almost unchanged. Description of the Drawings

[0058] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present disclosure and should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0059] Figure 1 SEM image of the nickel-iron-manganese-copper hydroxide precursor prepared for Example 1;

[0060] Figure 2 SEM image of the nickel-iron-manganese-copper hydroxide precursor prepared for Comparative Example 1;

[0061] Figure 3 SEM image of the nickel-iron-manganese-copper hydroxide precursor prepared for Comparative Example 2;

[0062] Figure 4 SEM image of the nickel-iron-manganese-copper hydroxide precursor prepared for Comparative Example 3. Detailed implementation manners

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0064] The nickel-iron-manganese-copper precursor provided in the present application, its preparation method, and applications will be specifically described below.

[0065] To address the problems of the nickel-iron-manganese-copper hydroxide precursor having many lattice defects, poor morphology, and high impurity content (especially sulfur content), the inventors attempted to add a complexing agent such as ammonia water during the coprecipitation process. Although this method can effectively complex nickel ions and copper ions, its complexing effect on manganese ions is weak, and it has almost no complexing effect on ferrous ions, making it impossible to achieve uniform coprecipitation of each element and having little effect on reducing the sulfur content in the product. If the reaction pH is increased (for example, increased by 0.1 - 1.0), although this method increases the hydroxide ion concentration in the reaction system, the K sp values of the hydroxides of the four metal elements vary greatly, making it even more difficult to achieve uniform coprecipitation, and the morphology deteriorates more severely, and the sulfur content does not decrease significantly. In addition, if the amount and number of alkali washes are increased, due to the originally high sulfur content of the precursor, the substitution reaction of hydroxide ions for sulfate ions during alkali washing is too intense, resulting in serious damage to the precursor structure, a large number of small fragments appear, and the particle size is severely reduced.

[0066] Through continuous exploration, the inventor creatively obtained a nickel-iron-manganese-copper precursor with low sulfur content and capable of maintaining a good particle morphology.

[0067] The molecular formula of the nickel-iron-manganese-copper precursor is Ni a Fe b Mn c Cu d (OH) 2 , where 0.1 ≤ a ≤ 0.8, 0.1 ≤ b ≤ 0.8, 0.1 ≤ c ≤ 0.8, 0.02 ≤ d ≤ 0.5, and a + b + c + d = 1.

[0068] The nickel-iron-manganese-copper precursor is in particulate form and the sulfur content does not exceed 1200 ppm.

[0069] In some embodiments, the nickel-iron-manganese-copper precursor is in particulate form, the sulfur content does not exceed 1200 ppm, the specific surface area does not exceed 50 m 2 / g and the tapped density is not less than 1.25 g / cm 3 .

[0070] Furthermore, the above nickel-iron-manganese-copper precursor may further satisfy at least one of the following particle size ranges: D 10 not less than 4 μm, D 50 not less than 9 μm, D 90 not higher than 27 μm.

[0071] As a reference, in some embodiments, the nickel-iron-manganese-copper precursor has the following characteristics: being in a complete particulate form; and / or, the sulfur content is 792 - 929 ppm; and / or, the specific surface area is 34.2 - 41.5 m 2 / g; and / or, the tapped density is 1.26 - 1.42 g / cm 3 ; and / or, D 10 is 5.22 - 6.07 μm; and / or, D 50 is 9.42 - 11.27 μm; and / or, D 90 is 19.73 - 24.86 μm.

[0072] Correspondingly, the present disclosure also provides a method for preparing the above nickel-iron-manganese-copper precursor, which mainly includes the following steps: mixing an intermediate precursor with an antioxidant, a complexing agent, and a precipitating agent for deep coprecipitation and preliminary desulfurization treatment.

[0073] Wherein, the intermediate precursor is obtained by preliminary coprecipitation of a nickel-iron-manganese-copper mixed metal sulfate solution and a precipitating agent according to the preset molecular formula of the nickel-iron-manganese-copper precursor.

[0074] The preliminary coprecipitation can be carried out, for example, in a reaction kettle. Pure water can be used as the bottom liquid in the reaction kettle, and the nickel-iron-manganese-copper mixed metal sulfate solution and the precipitant are simultaneously introduced into the reaction kettle. The concentration of the mixed metals in the nickel-iron-manganese-copper mixed metal sulfate solution can be 1-2 mol / L. The flow rate at which it is introduced into the reaction kettle can be 10-50 L / h.

[0075] The precipitant can be, for example, a sodium hydroxide solution.

[0076] For reference, the reaction temperature of the above-mentioned preliminary coprecipitation can be 30-85 °C, such as 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C or 85 °C, etc., or can also be any other value within the range of 30-85 °C.

[0077] The reaction pH value of the preliminary coprecipitation can be 8-11, such as 8, 8.5, 9, 9.5, 10, 10.5 or 11, etc., or can also be any other value within the range of 8-11.

[0078] The above-mentioned preliminary coprecipitation can be carried out under stirring conditions. Exemplarily, the stirring speed can be 200-500 rpm, such as 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm, etc., or can also be any other value within the range of 200-500 rpm.

[0079] A protective gas can also be introduced during the preliminary coprecipitation process. Exemplarily, the protective gas can include inert gases (such as argon, etc.).

[0080] During the above-mentioned preliminary coprecipitation process of the present disclosure, a complexing agent can be selectively added. That is, during the specific preparation, the complexing agent can be added or not added according to needs. When a complexing agent needs to be added, the complexing agent, the nickel-iron-manganese-copper mixed metal sulfate solution and the precipitant are jointly introduced into the reaction kettle.

[0081] For reference, the complexing agent can include at least one of ammonia water (the concentration of ammonia water can be 10-25 wt%), sodium citrate, ammonium citrate, EDTA and sodium oxalate. When the particle size of the intermediate precursor obtained by the preliminary coprecipitation reaches the required particle size (such as 9-12 μm), the feed liquid at this time is subjected to deep coprecipitation and preliminary desulfurization treatment.

[0082] In some embodiments, the feed liquid containing the intermediate precursor with a particle size reaching the requirement can be introduced into an aging tank for deep coprecipitation and preliminary desulfurization treatment. In addition, other containers can also be used instead of the aging tank according to needs.

[0083] As a reference ground, the antioxidants used in the deep coprecipitation and preliminary desulfurization treatment process may include, for example, at least one of ascorbic acid, sodium erythorbate, vitamin E, carotenoids, and anthocyanins.

[0084] The addition amount of the antioxidant can be, for example, 0.001 - 0.1 mol / L, such as 0.001 mol / L, 0.002 mol / L, 0.005 mol / L, 0.008 mol / L, 0.01 mol / L, 0.02 mol / L, 0.05 mol / L, 0.08 mol / L, or 0.1 mol / L, etc., or it can also be any other value within the range of 0.001 - 0.1 mol / L. In other words, 0.001 - 0.1 mol of antioxidant can be used corresponding to each liter of the feed liquid containing the intermediate precursor with the required particle size.

[0085] By adding the antioxidant under the above conditions, the formation of oxides or hydroxyoxides of the material can be prevented to a certain extent, such as copper hydroxide becoming copper oxide / cuprous oxide, and ferrous hydroxide becoming ferric oxyhydroxide.

[0086] If the addition amount of the antioxidant exceeds 0.1 mol / L, it is not conducive to cost reduction.

[0087] As a reference ground, the complexing agents used in the deep coprecipitation and preliminary desulfurization treatment process may include, for example, at least one of ammonia water, ammonium citrate, sodium citrate, EDTA, and sodium oxalate.

[0088] The addition amount of the complexing agent can be, for example, 0.01 - 0.5 mol / L, such as 0.01 mol / L, 0.02 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, or 0.5 mol / L, etc., or it can also be any other value within the range of 0.01 - 0.5 mol / L. In other words, 0.01 - 0.5 mol of complexing agent can be used corresponding to each liter of the feed liquid containing the intermediate precursor with the required particle size.

[0089] By adding the complexing agent under the above conditions, the complexing agent can complex with metal ions to reduce the reaction rate and avoid large damage on the surface of the precursor.

[0090] If the addition amount of the complexing agent exceeds 0.5 mol / L, the precipitation rate of metal ions will be reduced.

[0091] As a reference ground, the precipitant used in the deep coprecipitation and preliminary desulfurization treatment process may include, for example, sodium hydroxide solution.

[0092] The concentration of the precipitant used in this process can be, for example, 5 - 10 mol / L, such as 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L, etc. By introducing the precipitant, the pH of the reaction system is made to be 10 - 13, such as 10, 10.5, 11, 11.5, 12, 12.5 or 13, etc., and can also be any other value within the range of 10 - 13.

[0093] Adding the precipitant is mainly used for the substitution reaction of sulfate radicals in the precursor to preliminarily reduce the sulfur content of the material.

[0094] If the pH value in this process is less than 10, it is not conducive to sulfur removal; if the pH value is greater than 13, it is not conducive to maintaining the particle morphology.

[0095] By adding the liquid slowly at the above speed (completing the required sodium hydroxide solution within 0.5 - 2 h), violent reactions can be prevented.

[0096] In the present disclosure, the deep coprecipitation and preliminary desulfurization treatment is carried out under heating and stirring conditions. The corresponding temperature can be 50 - 80 °C, and the stirring speed can be 100 - 500 rpm.

[0097] Carrying out heating and stirring under the above conditions is conducive to guiding the occurrence of the reaction and enabling the small amount of hydroxides precipitated in the substitution reaction to quickly attach and grow on the existing particles.

[0098] When the pH reaches 10 - 13 during the deep coprecipitation and preliminary desulfurization treatment process, stop adding the precipitant and continue to stir the material liquid. The time for continuous stirring can be, by way of example, 0.5 - 2 h, such as 0.5 h, 1 h, 1.5 h or 2 h, etc., and can also be any other value within the range of 0.5 - 2 h. The stirring speed for continuous stirring can also be 100 - 500 rpm.

[0099] Furthermore, the material obtained from the deep coprecipitation and preliminary desulfurization treatment is subjected to deep desulfurization.

[0100] Referentially, deep desulfurization includes: dehydrating the material and rinsing the dehydrated solid with a desulfurization solution.

[0101] Dehydration can be carried out, by way of example, in a centrifuge. After dehydration, introduce a desulfurization solution into the centrifuge to rinse the filter cake for deep desulfurization.

[0102] In some embodiments, the desulfurization solution can include a sodium hydroxide solution, and the concentration of this sodium hydroxide solution can be 0.6 - 1.8 mol / L, such as 0.6 mol / L, 0.8 mol / L, 1.0 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L or 1.8 mol / L, etc., and can also be any other value within the range of 0.6 - 1.8 mol / L.

[0103] If the concentration of the above sodium hydroxide solution is less than 0.6 mol / L, it is not conducive to sulfur removal; if the concentration of the above sodium hydroxide solution is greater than 1.8 mol / L, it is not conducive to maintaining the particle morphology.

[0104] In some other embodiments, the desulfurization solution may further contain a complexing agent, and the complexing agent may include, for example, at least one of ammonia water, sodium citrate, ammonium citrate, EDTA, and sodium oxalate.

[0105] Exemplarily, the concentration of the complexing agent contained in the desulfurization solution can be 0.01 - 0.5 mol / L, such as 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, or 0.5 mol / L, etc., or any other value within the range of 0.01 - 0.5 mol / L.

[0106] By adding the complexing agent according to the above conditions, it is beneficial to inhibit the destruction of the particle morphology. In addition, the case where no complexing agent is added during the deep desulfurization process is not excluded.

[0107] Furthermore, the solid material after being rinsed with the desulfurization solution is washed with water and then dried (such as by baking).

[0108] As mentioned above, the method provided by the present disclosure is relatively easy to operate and implement. The nickel-iron-manganese-copper hydroxide intermediate precursor prepared by preliminary coprecipitation has a sulfur content of about 20000 - 60000 ppm. Calculated at an average value of 40000 ppm, it is equivalent to that the precursor particles themselves are a solid solution composed of approximately 20% sulfate and 80% hydroxide. The sulfate radical in the crystal is difficult to wash off with pure water and has to be replaced by hydroxide bit by bit. The present disclosure first performs deep coprecipitation on the intermediate precursor, and in this process, it can simultaneously achieve the effect of preliminary sulfur removal, reducing the sulfur content from 40000 ppm to about 3000 ppm. Moreover, the complexing agent and antioxidant added during this process can protect the particles. By slowly adding the precipitating agent, it can replace the sulfate radical while preventing the particles from being damaged due to violent reactions; then through subsequent deep desulfurization, the sulfur content can be reduced from 3000 ppm to about 800 ppm, and this method can keep the particle morphology almost unchanged.

[0109] In addition, the present disclosure also provides a positive electrode material (such as a positive electrode material for a sodium-ion battery), and its preparation raw materials include the above nickel-iron-manganese-copper precursor. Further, the present disclosure also provides a battery (such as a sodium-ion battery) containing the above positive electrode material, and the corresponding battery can have better electrochemical performance.

[0110] It should be noted that the preparation methods of the cathode material and the battery can refer to the conventional methods in the art and will not be elaborated here.

[0111] The features and properties of the present disclosure will be further described in detail below in conjunction with the embodiments.

[0112] Example 1

[0113] This example provides a nickel-iron-manganese-copper hydroxide precursor with the molecular formula Ni 0.25 Fe 0.25 Mn 0.35 Cu 0.15 (OH) 2 , and its preparation method is as follows:

[0114] S1: Preliminary coprecipitation to prepare an intermediate precursor.

[0115] A 2 mol / L nickel-iron-manganese-copper mixed solution prepared according to the atomic ratio of nickel, iron, manganese, and copper of 0.25:0.25:0.35:0.15, sodium hydroxide solution (precipitant), and ammonia water (complexing agent) are simultaneously introduced into the reaction kettle. The preliminary coprecipitation reaction is carried out under a nitrogen atmosphere, with a stirring speed of 400 rpm, a temperature of 50 °C, and a pH value of 10.5 to obtain an intermediate precursor.

[0116] After the kettle is full, continue to add liquid for reaction. The overflowing material enters the aging tank through the overflow port, and the material with the required particle size (10 - 11 μm) is collected for the next step of treatment.

[0117] S2: Deep coprecipitation and preliminary desulfurization treatment.

[0118] After the aging tank collects enough material, ascorbic acid (antioxidant) and ammonia water (complexing agent) are added to the aging tank. The concentrations of ascorbic acid and ammonia water in the liquid in the aging tank are 0.005 mol / L and 0.2 mol / L respectively. Start stirring (rotation speed of 300 rpm), heating (temperature of 55 °C), and then slowly introduce 10 mol / L sodium hydroxide solution into the aging tank. Finish introducing it in 1 h, with the final pH value of 12.3, and then stir for another 2 h.

[0119] S3: Deep desulfurization treatment.

[0120] The material in the aging tank is introduced into a centrifuge for dehydration. A desulfurization solution containing 1 mol / L sodium hydroxide solution and 0.1 mol / L ammonia water is introduced into the centrifuge to wash the filter cake for desulfurization again, and then pure water is introduced for washing. The filter cake in the centrifuge is taken out, dried, and sieved to obtain the required nickel-iron-manganese-copper hydroxide precursor.

[0121] Example 2

[0122] This example provides a nickel-iron-manganese-copper hydroxide precursor with a molecular formula of Ni 0.20 Fe 0.20 Mn 0.40 Cu 0.20 (OH) 2 , and its preparation method is as follows:

[0123] S1: Prepare an intermediate precursor by preliminary coprecipitation.

[0124] A 1.7 mol / L nickel-iron-manganese-copper mixed solution prepared according to an atomic ratio of nickel, iron, manganese, and copper of 0.20:0.20:0.40:0.20, a sodium hydroxide solution (precipitant), and an ammonium citrate solution (complexing agent) are simultaneously introduced into a reaction kettle. A preliminary coprecipitation reaction is carried out under a nitrogen atmosphere, with a stirring speed of 350 rpm, a temperature of 55 °C, and a pH value of 10.2 to obtain an intermediate precursor.

[0125] After the kettle is full, continue the liquid addition reaction. The overflowing material enters the aging tank through the overflow port, and the material with a particle size meeting the requirements (10 - 11 μm) is collected for the next step of treatment.

[0126] S2: Deep coprecipitation and preliminary desulfurization treatment.

[0127] After the aging tank collects enough material, ascorbic acid (antioxidant) and ammonium citrate (complexing agent) are added to the aging tank. The concentrations of ascorbic acid and ammonium citrate in the liquid in the aging tank are 0.01 mol / L and 0.03 mol / L respectively. Start stirring (at a speed of 300 rpm) and heating (at a temperature of 65 °C), and then slowly introduce a 10 mol / L sodium hydroxide solution into the aging tank. Finish introducing it in 1 h, with an end point pH value of 12.2, and then stir for another 2 h.

[0128] S3: Deep desulfurization treatment.

[0129] The material in the aging tank is introduced into a centrifuge for dehydration. A desulfurization solution containing 1 mol / L sodium hydroxide solution and 0.03 mol / L ammonium citrate is introduced into the centrifuge to wash the filter cake for desulfurization again, and then pure water is introduced for washing. The filter cake in the centrifuge is taken out, dried, and sieved to obtain the required nickel-iron-manganese-copper hydroxide precursor.

[0130] Example 3

[0131] This example provides a nickel-iron-manganese-copper hydroxide precursor with a molecular formula of Ni 0.15 Fe 0.15 Mn 0.55 Cu 0.15 (OH) 2 , and its preparation method is as follows:

[0132] S1: Prepare an intermediate precursor by preliminary coprecipitation.

[0133] A 1.5 mol / L nickel-iron-manganese-copper mixed solution prepared according to the atomic ratio of nickel:iron:manganese:copper of 0.15:0.15:0.55:0.15, sodium hydroxide solution (precipitant), and sodium citrate solution (complexing agent) are simultaneously introduced into a reaction kettle. A preliminary coprecipitation reaction is carried out under a nitrogen atmosphere, with a stirring speed of 450 rpm, a temperature of 45 °C, and a pH value of 10.6 to obtain an intermediate precursor.

[0134] After the kettle is full, continue the liquid addition reaction. The overflowing material enters the aging tank through the overflow port. Collect the material with a particle size meeting the requirements (11 - 12 μm) for the next step of treatment.

[0135] S2: Deep coprecipitation and preliminary desulfurization treatment.

[0136] After the aging tank collects enough material, sodium erythorbate (antioxidant) and sodium citrate (complexing agent) are added to the aging tank. The concentrations of sodium erythorbate and sodium citrate in the aging tank are 0.01 mol / L and 0.03 mol / L respectively. Start stirring (rotation speed of 400 rpm), heating (temperature of 50 °C), and then slowly introduce a 10 mol / L sodium hydroxide solution into the aging tank. Finish introducing it in 1.5 h, with an end point pH value of 12.6, and then stir for another 1 h.

[0137] S3: Deep desulfurization treatment.

[0138] The material in the aging tank is introduced into a centrifuge for dehydration. A desulfurization solution containing 0.8 mol / L sodium hydroxide solution and 0.02 mol / L sodium citrate is introduced into the centrifuge to wash the filter cake for desulfurization again, and then pure water is introduced for washing. The filter cake in the centrifuge is taken out, dried, and sieved to obtain the required nickel-iron-manganese-copper hydroxide precursor.

[0139] Example 4

[0140] This example provides a nickel-iron-manganese-copper hydroxide precursor with the molecular formula Ni 0.25 Fe 0.25 Mn 0.39 Cu 0.11 (OH) 2 , and its preparation method is as follows:

[0141] S1: Prepare an intermediate precursor by preliminary coprecipitation.

[0142] A 1.7 mol / L nickel-iron-manganese-copper mixed solution prepared with an atomic ratio of nickel, iron, manganese, and copper of 0.25:0.25:0.39:0.11 is simultaneously introduced into a reaction kettle together with sodium hydroxide solution (precipitant) and sodium citrate solution (complexing agent). A preliminary coprecipitation reaction is carried out while maintaining a nitrogen atmosphere, a stirring speed of 400 rpm, a temperature of 65 °C, and a pH value of 9.9 to obtain an intermediate precursor.

[0143] After the kettle is full, the liquid addition reaction continues. The overflowing material enters the aging tank through the overflow port, and the material with a particle size meeting the requirements (11 - 12 μm) is collected for the next treatment.

[0144] S2: Deep coprecipitation and preliminary desulfurization treatment.

[0145] After the aging tank collects enough material, vitamin E (antioxidant) and sodium oxalate (complexing agent) are added to the aging tank. The concentrations of vitamin E and sodium oxalate in the liquid of the aging tank are 0.005 mol / L and 0.01 mol / L respectively. Stirring is started (rotation speed is 300 rpm), heating is carried out (temperature is 70 °C), and then a 10 mol / L sodium hydroxide solution is slowly introduced into the aging tank. It is completed in 2 h, the final pH value is 12.0, and then stirring is continued for 2 h.

[0146] S3: Deep desulfurization treatment.

[0147] The material in the aging tank is introduced into a centrifuge for dehydration. A desulfurization solution containing 1.2 mol / L sodium hydroxide solution and 0.01 mol / L sodium oxalate is introduced into the centrifuge, and then pure water is introduced for washing. The filter cake in the centrifuge is taken out, dried, and sieved to obtain the required nickel-iron-manganese-copper hydroxide precursor.

[0148] Example 5

[0149] This example provides a nickel-iron-manganese-copper hydroxide precursor with the molecular formula Ni 0.25 Fe 0.25 Mn 0.39 Cu 0.11 (OH) 2 , and its preparation method is as follows:

[0150] S1: Preliminary coprecipitation to prepare an intermediate precursor.

[0151] A 1.5 mol / L nickel-iron-manganese-copper mixed solution prepared with an atomic ratio of nickel, iron, manganese, and copper of 0.25:0.25:0.39:0.11 is simultaneously introduced into a reaction kettle together with sodium hydroxide solution (precipitant) and sodium citrate solution (complexing agent). A preliminary coprecipitation reaction is carried out while maintaining a nitrogen atmosphere, a stirring speed of 350 rpm, a temperature of 75 °C, and a pH value of 9.8 to obtain an intermediate precursor.

[0152] After the kettle is full, continue to add liquid for reaction. The overflowing material enters the aging tank through the overflow port, and the material with the particle size meeting the requirements (9 - 10 μm) is collected for the next step of treatment.

[0153] S2: Deep coprecipitation and preliminary desulfurization treatment.

[0154] After the aging tank collects enough material, add carotenoid (antioxidant) and EDTA (complexing agent) to the aging tank. The concentrations of carotenoid and EDTA in the liquid of the aging tank are 0.01 mol / L and 0.005 mol / L respectively. Start stirring (rotation speed is 350 rpm), heating (temperature is 55 °C), and then slowly introduce 10 mol / L sodium hydroxide solution into the aging tank. Finish introducing it in 0.8 h, the end point pH value is 12.5, and then stir for another 2 h.

[0155] S3: Deep desulfurization treatment.

[0156] Pass the material in the aging tank into a centrifuge for dehydration, introduce a desulfurization solution containing 1.2 mol / L sodium hydroxide solution and 0.005 mol / L EDTA into the centrifuge, and then introduce pure water for washing. Take out the filter cake in the centrifuge, dry it, and sieve it to obtain the required nickel - iron - manganese - copper hydroxide precursor.

[0157] Example 6

[0158] This example provides a nickel - iron - manganese - copper hydroxide precursor with the molecular formula Ni 0.25 Fe 0.25 Mn 0.35 Cu 0.15 (OH) 2 , and its preparation method is as follows:

[0159] S1: Preliminary coprecipitation to prepare an intermediate precursor.

[0160] Simultaneously introduce a 2 mol / L nickel - iron - manganese - copper mixed solution prepared according to the atomic ratio of nickel, iron, manganese, and copper of 0.25:0.25:0.35:0.15, sodium hydroxide solution (precipitant), and EDTA (complexing agent) into the reaction kettle, maintain an argon atmosphere, a stirring speed of 200 rpm, a temperature of 40 °C, and a pH value of 10.5 for preliminary coprecipitation reaction to obtain an intermediate precursor.

[0161] After the kettle is full, continue to add liquid for reaction. The overflowing material enters the aging tank through the overflow port, and the material with the particle size meeting the requirements (10 - 11 μm) is collected for the next step of treatment.

[0162] S2: Deep coprecipitation and preliminary desulfurization treatment.

[0163] After the aging tank has collected enough materials, add anthocyanin (antioxidant) and ammonia water (complexing agent) to the aging tank. The concentrations of ascorbic acid and ammonia water in the liquid of the aging tank are 0.001 mol / L and 0.01 mol / L respectively. Start stirring (rotation speed is 350 rpm), heating (temperature is 75 °C), and then slowly introduce 10 mol / L sodium hydroxide solution into the aging tank. Finish introducing it in 0.5 h, and the final pH value is 11.0. Then stir for another 2 h.

[0164] S3: Deep desulfurization treatment.

[0165] Pass the materials in the aging tank into a centrifuge for dehydration. Pass a desulfurization solution containing 0.6 mol / L sodium hydroxide solution and 0.01 mol / L sodium citrate into the centrifuge to wash the filter cake for desulfurization again, and then pass pure water for washing. Take out the filter cake in the centrifuge, dry it, and sieve it to obtain the required nickel-iron-manganese-copper hydroxide precursor.

[0166] Example 7

[0167] This example provides a nickel-iron-manganese-copper hydroxide precursor with the molecular formula Ni 0.25 Fe 0.25 Mn 0.35 Cu 0.15 (OH) 2 , and its preparation method is as follows:

[0168] S1: Preliminary coprecipitation to prepare an intermediate precursor.

[0169] Simultaneously introduce a 2 mol / L nickel-iron-manganese-copper mixed solution prepared according to the atomic ratio of nickel, iron, manganese, and copper of 0.25:0.25:0.35:0.15, sodium hydroxide solution (precipitating agent), and sodium oxalate solution (complexing agent) into the reaction kettle. Keep a nitrogen atmosphere, stirring speed of 500 rpm, temperature of 85 °C, and pH value of 8.5 for preliminary coprecipitation reaction to obtain an intermediate precursor.

[0170] After the kettle is full, continue the liquid addition reaction. The overflowing materials enter the aging tank through the overflow port. Collect the materials with particle size reaching the requirements (9 - 11 μm) for the next step of treatment.

[0171] S2: Deep coprecipitation and preliminary desulfurization treatment.

[0172] After the aging tank has collected enough materials, add ascorbic acid (antioxidant) and ammonia water (complexing agent) to the aging tank. The concentrations of ascorbic acid and ammonia water in the liquid of the aging tank are 0.02 mol / L and 0.5 mol / L respectively. Start stirring (rotation speed is 300 rpm), heating (temperature is 50 °C), and then slowly introduce 10 mol / L sodium hydroxide solution into the aging tank. Finish introducing it in 2 h, and the final pH value is 12.8. Then stir for another 2 h.

[0173] S3: Deep desulfurization treatment.

[0174] The materials in the aging tank are fed into a centrifuge for dehydration. A desulfurization solution containing 1.2 mol / L of sodium hydroxide solution and 0.005 mol / L of EDTA is fed into the centrifuge to wash the filter cake for desulfurization again, and then pure water is fed in for washing. The filter cake in the centrifuge is taken out, dried, and sieved to obtain the required nickel-iron-manganese-copper hydroxide precursor.

[0175] Comparative Example 1

[0176] The difference between this comparative example and Example 1 is that:

[0177] In S2, ascorbic acid and ammonia water are not added; in S3, ammonia water is not added.

[0178] Comparative Example 2

[0179] The difference between this comparative example and Example 1 is that:

[0180] In S2, after the aging tank collects enough materials, ascorbic acid and ammonia water are not added, stirring and heating are started, and then 10 mol / L sodium hydroxide solution is poured into the aging tank at one time to raise the pH value to 12.3, and then stirring is continued for 2 h.

[0181] In S3, ammonia water is not added.

[0182] Comparative Example 3

[0183] The difference between this comparative example and Example 1 is that:

[0184] S3 is directly carried out after S1, and ammonia water is not added in S3.

[0185] Comparative Example 4

[0186] The difference between this comparative example and Example 1 is that the deep desulfurization treatment of S3 is not carried out.

[0187] Comparative Example 5

[0188] The difference between this comparative example and Example 1 is that the pH value is 13.1 during the deep coprecipitation and preliminary desulfurization treatment.

[0189] Comparative Example 6

[0190] The difference between this comparative example and Example 1 is that the precipitant is quickly added (added within 5 min) during the deep coprecipitation and preliminary desulfurization treatment.

[0191] Test Example 1

[0192] Taking the nickel-iron-manganese-copper hydroxide precursors prepared in Example 1 and Comparative Examples 1-3 as examples, the morphology was observed respectively, and the corresponding SEM images are as Figures 1 to 4 shown.

[0193] Among them, Figure 1 is the SEM image of the precursor particles obtained in Example 1. The process of this example includes two-stage washing to remove sulfur, and antioxidants and complexing agents are added to protect the particle morphology. The obtained precursor particles are relatively complete.

[0194] Figure 2 is the SEM image of the precursor particles obtained in Comparative Example 1. The process of this comparative example also includes two-stage washing to remove sulfur, but antioxidants and complexing agents are not added. Some small fragments appear in the obtained precursor particles.

[0195] Figure 3 is the SEM image of the precursor particles obtained in Comparative Example 2. Compared with Comparative Example 1, 10 mol / L sodium hydroxide solution is poured into the aging tank at one time, and the particle morphology is more severely damaged.

[0196] Figure 4 is the SEM image of the precursor particles obtained in Comparative Example 3. The process of this comparative example only includes one-stage washing to remove sulfur, and antioxidants and complexing agents are not added. The particle morphology in the SEM image is the most severely damaged.

[0197] Test Example 2

[0198] The particle size, sulfur content, specific surface area and tapped density of the nickel-iron-manganese-copper hydroxide precursors obtained in the above Examples 1-7 and Comparative Examples 1-6 were measured, and the results are shown in Table 1.

[0199] Table 1 Detection data of precursor samples

[0200]

[0201]

[0202] It can be seen from Table 1 that: compared with Example 1, in Comparative Example 1, the particle size and TD slightly decrease, the BET slightly increases, and the sulfur content is not much different; compared with Example 1, in Comparative Example 2, the particle size and TD decrease, the BET increases, the particles are deteriorated more severely than in Comparative Example 1, and the sulfur content is not much different; compared with Example 1, in Comparative Example 3, the particle size and TD decrease severely, the BET increases greatly, the sulfur content exceeds 4000 ppm, and the particles are deteriorated most severely. The above results are consistent with the results of the SEM images in Test Example 1.

[0203] The detection data of the remaining samples are also good. The detection data of Comparative Examples 4-6 are not as good as those of the Examples.

[0204] The data of the above examples and comparative examples show that the two-stage washing process and appropriate process conditions can reduce the sulfur content to no more than 1200 ppm, and even down to about 800 ppm. Antioxidants and complexing agents can play a role in protecting the particle morphology.

[0205] Industrial Applicability

[0206] The nickel-iron-manganese-copper precursor method provided by the present disclosure is relatively easy to operate and implement, and can obtain a nickel-iron-manganese-copper precursor with a low sulfur content and a good particle morphology, which has good application value in the preparation of cathode materials for sodium-ion batteries and sodium-ion batteries.

Claims

1. A nickel-iron-manganese-copper precursor, characterized in that, The molecular formula of the nickel-iron-manganese-copper precursor is Ni a Fe b Mn c Cu d (OH) 2 , where 0.1 ≤ a ≤ 0.8, 0.1 ≤ b ≤ 0.8, 0.1 ≤ c ≤ 0.8, 0.02 ≤ d ≤ 0.5, and a + b + c + d = 1; the nickel-iron-manganese-copper precursor is granular and the sulfur content does not exceed 1200 ppm; and the nickel-iron-manganese-copper precursor further has the following characteristics: Feature 1: The specific surface area of the nickel-iron-manganese-copper precursor does not exceed 50 m 2 / g; Feature 2: The tap density of the nickel-iron-manganese-copper precursor is not less than 1.25 g / cm 3 ; the nickel-iron-manganese-copper precursor further has at least one of the following characteristics: Feature Three: The D of the nickel-iron-manganese-copper precursor 10 is not less than 4 μm; Feature Four: The D of the nickel-iron-manganese-copper precursor 50 is not less than 9 μm; Feature Five: The D of the nickel-iron-manganese-copper precursor 90 is not higher than 27 μm.

2. The nickel-iron-manganese-copper precursor according to claim 1, characterized in that, the nickel-iron-manganese-copper precursor is in the form of complete granules; and / or, the sulfur content of the nickel-iron-manganese-copper precursor is 792 - 929 ppm; and / or, the specific surface area of the nickel-iron-manganese-copper precursor is 34.2-41.5 m 2 / g; and / or, the tap density of the nickel-iron-manganese-copper precursor is 1.26-1.42 g / cm 3 ; and / or, D of the nickel-iron-manganese-copper precursor 10 is 5.22 - 6.07 μm; and / or, D of the nickel-iron-manganese-copper precursor 50 is 9.42 - 11.27 μm; and / or, the D of the nickel-iron-manganese-copper precursor 90 is 19.73 - 24.86 μm.

3. A method for preparing the nickel-iron-manganese-copper precursor according to claim 1 or 2, characterized in that, it includes the following steps: mixing an intermediate precursor with an antioxidant, a complexing agent, and a precipitating agent for deep coprecipitation and preliminary desulfurization treatment; wherein, the intermediate precursor is obtained by preliminary coprecipitation of a nickel-iron-manganese-copper mixed metal sulfate solution and a precipitating agent according to the preset molecular formula of the nickel-iron-manganese-copper precursor.

4. The preparation method according to claim 3, characterized in that, the precipitating agent includes a sodium hydroxide solution.

5. The preparation method according to claim 3 or 4, characterized in that, during the preliminary coprecipitation process, a complexing agent is further added.

6. The preparation method according to claim 5, characterized in that, the complexing agent includes at least one of ammonia water, sodium citrate, ammonium citrate, EDTA, and sodium oxalate.

7. The preparation method according to claim 3, characterized in that, the reaction temperature of the preliminary coprecipitation is 30 - 85 °C; and / or, the reaction pH value of the preliminary coprecipitation is 8 - 11.

8. The preparation method according to claim 3, characterized in that, the preliminary coprecipitation is carried out under stirring conditions.

9. The preparation method according to claim 8, characterized in that, the stirring speed is 200 - 500 rpm.

10. The preparation method according to claim 3, characterized in that, a protective gas is introduced during the preliminary coprecipitation process.

11. The preparation method according to claim 10, characterized in that, the protective gas includes an inert gas.

12. The preparation method according to claim 3, characterized in that, the antioxidant includes at least one of ascorbic acid, sodium erythorbate, vitamin E, carotenoids, and anthocyanins.

13. The preparation method according to claim 12, characterized in that, the addition amount of the antioxidant is 0.001 - 0.1 mol / L.

14. The preparation method according to claim 3, characterized in that, the complexing agent used in the deep coprecipitation and preliminary desulfurization treatment process includes at least one of ammonia water, ammonium citrate, sodium citrate, EDTA, and sodium oxalate.

15. The preparation method according to claim 14, characterized in that, the addition amount of the complexing agent in the deep coprecipitation and preliminary desulfurization treatment process is 0.01 - 0.5 mol / L.

16. The preparation method according to claim 14, characterized in that, the precipitating agent used in the deep coprecipitation and preliminary desulfurization treatment process includes a sodium hydroxide solution.

17. The preparation method according to claim 16, characterized in that, The concentration of the precipitant used in the deep coprecipitation and preliminary desulfurization treatment process is 5-10 mol / L, and the addition time is 0.5-2 h.

18. According to the preparation method described in claim 3, wherein, the temperature of the deep coprecipitation and preliminary desulfurization treatment process is 50-80 °C.

19. According to the preparation method described in claim 3, wherein, during the deep coprecipitation and preliminary desulfurization treatment process, when the pH value of the deep coprecipitation system is 10-13, the feeding is stopped.

20. According to the preparation method described in claim 3, wherein, the deep coprecipitation and preliminary desulfurization treatment is carried out under stirring conditions.

21. According to the preparation method described in claim 20, wherein, the stirring speed during the deep coprecipitation and preliminary desulfurization treatment process is 100-500 rpm.

22. According to the preparation method described in claim 3, wherein, it further includes deeply desulfurizing the material obtained from the deep coprecipitation and preliminary desulfurization treatment.

23. According to the preparation method described in claim 22, wherein, the deep desulfurization includes: dehydrating the material, and rinsing the dehydrated solid with a desulfurization solution.

24. According to the preparation method described in claim 23, wherein, the desulfurization solution includes a sodium hydroxide solution.

25. According to the preparation method described in claim 24, wherein, the concentration of the sodium hydroxide solution as the desulfurization solution is 0.6-1.8 mol / L.

26. According to the preparation method described in claim 24, wherein, the desulfurization solution further contains a complexing agent.

27. According to the preparation method described in claim 26, wherein, the complexing agent contained in the desulfurization solution includes at least one of ammonia water, sodium citrate, ammonium citrate, EDTA, and sodium oxalate.

28. According to the preparation method described in claim 27, wherein, the concentration of the complexing agent contained in the desulfurization solution is 0.01-0.5 mol / L.

29. According to the preparation method described in claim 23, wherein, the solid washed with the desulfurization solution is washed with water and then dried.

30. A cathode material, wherein, the raw materials for preparing the cathode material include the nickel-iron-manganese-copper precursor described in claim 1 or 2.

31. A battery, wherein, the battery contains the cathode material described in claim 30.

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