Sodium-ion battery precursor, positive electrode material, preparation method, and use

Abstract

The present application relates to a sodium-ion battery precursor, a positive electrode material, a preparation method, and a use. A complexing agent solution used for preparing the sodium-ion battery precursor comprises a first complexing agent and a second complexing agent, wherein the first complexing agent comprises any one of or a combination of at least two of oxalic acid, sodium oxalate, or potassium oxalate, and the second complexing agent comprises any one of or a combination of at least two of citric acid, sodium citrate, or potassium citrate. In the present application, by providing the specific complexing agents, the prepared sodium-ion battery precursor has a relatively high specific surface area, thereby facilitating the intercalation of sodium ions when sintering and preparing a positive electrode material, so that the electrochemical performance of the sodium-ion battery positive electrode material can be significantly improved.

Description

Sodium ion battery precursor, cathode material, preparation method and application Technical Field

[0001] The present application belongs to the field of battery technology and relates to a sodium ion battery, and in particular to a sodium ion battery precursor, a positive electrode material, a preparation method and an application. Background Art

[0002] The performance of sodium-ion batteries is primarily influenced by the cathode material. Layered oxide cathode materials offer advantages in both specific capacity and voltage, as well as inherent cost advantages. This is not only because these materials can be produced at low cost using the highly mature solid-phase or co-precipitation methods commonly used in lithium-ion batteries, but also because they offer a rich selection of active elements. In recent years, researchers have conducted numerous studies on the modification of copper-iron-manganese-sodium materials, finding that the incorporation of Cu and Fe can effectively suppress multiple phase transitions and reduce material costs. However, the material's relatively low capacity limits its large-scale application.

[0003] Coating a protective layer on the secondary particles can isolate the active material from the electrolyte, which can greatly improve the capacity of the material, but the operation is relatively cumbersome. Through a large number of experiments, it was found that the capacity of the positive electrode material can be increased by preparing a precursor with a high specific surface area (BET). Therefore, it is necessary to provide a sodium ion battery precursor, positive electrode material, preparation method and application that are simple and easy to use and can effectively increase the specific surface area of ​​the positive electrode material.

[0004] Summary of the Invention

[0005] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0006] The purpose of this application is to provide a sodium ion battery precursor, a positive electrode material, a preparation method and an application. The sodium ion battery precursor provided in this application has a high specific surface area, which facilitates the embedding of sodium ions when preparing the positive electrode material, and is beneficial to improving the electrochemical performance of the obtained positive electrode material.

[0007] To achieve this goal, this application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a method for preparing a sodium ion battery precursor, the preparation method comprising the following steps:

[0009] The ternary mixed salt solution, the precipitant solution and the complexing agent solution are simultaneously introduced into the bottom liquid to perform a co-precipitation reaction; when the particle size reaches the target particle size, the feeding is stopped and the reaction is continued until the material reaction is complete; and the solid-liquid separation is performed to obtain the sodium ion battery precursor;

[0010] The complexing agent in the complexing agent solution includes a first complexing agent and a second complexing agent;

[0011] The first complexing agent includes any one of oxalic acid, sodium oxalate or potassium oxalate or a combination of at least two of them. Typical but non-limiting combinations include a combination of oxalic acid and sodium oxalate, a combination of oxalic acid and potassium oxalate, a combination of sodium oxalate and potassium oxalate, or a combination of oxalic acid, sodium oxalate and potassium oxalate.

[0012] The second complexing agent includes any one of citric acid, sodium citrate or potassium citrate or a combination of at least two thereof. Typical but non-limiting combinations include a combination of citric acid and sodium citrate, a combination of sodium citrate and potassium citrate, a combination of citric acid and potassium citrate, or a combination of citric acid, sodium citrate and potassium citrate.

[0013] The preparation method provided in the present application uses two complexing agents in a complexing agent solution, so that the first complexing agent and the second complexing agent work together to increase the specific surface area of ​​the prepared sodium ion battery precursor, facilitate the embedding of sodium ions during the sintering process of preparing the positive electrode material, and thus help improve the electrochemical performance of the positive electrode material.

[0014] In one embodiment, the concentration of the first complexing agent in the complexing agent solution is 3-12 wt %.

[0015] In one embodiment, the concentration of the second complexing agent in the complexing agent solution is 3-12 wt %.

[0016] In one embodiment, the total concentration of the complexing agent in the complexing agent solution is 10-20 wt %.

[0017] In one embodiment, the ternary mixed salt solution is an iron, copper and manganese ternary mixed salt solution.

[0018] In one embodiment, the total concentration of metal salts in the ternary mixed salt solution is 50-150 g / L.

[0019] In one embodiment, the feed rate of the ternary mixed salt solution is 6-10 L / h.

[0020] In one embodiment, the precipitant solution comprises a sodium hydroxide solution having a concentration of 20-50 wt%.

[0021] In one embodiment, the temperature of the base liquid is 30-80°C.

[0022] In one embodiment, the pH value of the base solution is 10-12.

[0023] In one embodiment, the concentration of the complexing agent in the base solution is 1-10 g / L.

[0024] In one embodiment, the complexing agent in the base solution includes a third complexing agent and a fourth complexing agent.

[0025] In one embodiment, the third complexing agent includes any one of oxalic acid, sodium oxalate or potassium oxalate, or a combination of at least two of them.

[0026] In one embodiment, the fourth complexing agent includes any one of citric acid, sodium citrate or potassium citrate, or a combination of at least two thereof.

[0027] In one embodiment, the coprecipitation reaction is carried out under stirring conditions at a stirring speed of 200-400 r / min.

[0028] In one embodiment, during the coprecipitation reaction, the temperature of the reaction system is 30-80°C.

[0029] In one embodiment, during the coprecipitation reaction, the pH value of the reaction system is 9-11.

[0030] In one embodiment, during the coprecipitation reaction, the concentration of the complexing agent in the reaction system is 1-10 g / L.

[0031] In one embodiment, the coprecipitation reaction is carried out under a protective atmosphere.

[0032] In one embodiment, the target particle size is a particle size D50 of 6-8 μm.

[0033] In a second aspect, the present application provides a sodium ion battery precursor, which is prepared by the preparation method described in the first aspect.

[0034] In a third aspect, the present application provides a method for preparing a positive electrode material, the preparation method comprising the following steps:

[0035] A sodium source is mixed with the sodium ion battery precursor described in the second aspect, and sintered in an oxygen atmosphere to obtain the positive electrode material.

[0036] In a fourth aspect, the present application provides a positive electrode material, which is prepared by the preparation method described in the third aspect.

[0037] In a fifth aspect, the present application provides a battery, comprising the positive electrode material described in the fourth aspect.

[0038] Compared with the prior art, this application has the following beneficial effects:

[0039] The preparation method provided in the present application uses two complexing agents in a complexing agent solution, so that the first complexing agent and the second complexing agent work together to increase the specific surface area of ​​the prepared sodium ion battery precursor, facilitate the embedding of sodium ions during the sintering process of preparing the positive electrode material, and thus help improve the electrochemical performance of the positive electrode material.

[0040] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0042] FIG1 is a SEM image of the sodium ion battery precursor obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0043] The technical solution of the present application is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0044] The present invention provides a method for preparing a sodium ion battery precursor, which comprises the following steps:

[0045] The ternary mixed salt solution, the precipitant solution and the complexing agent solution are simultaneously introduced into the bottom liquid to perform a co-precipitation reaction; when the particle size reaches the target particle size, the feeding is stopped and the reaction is continued until the material reaction is complete; and the solid-liquid separation is performed to obtain the sodium ion battery precursor;

[0046] The complexing agent in the complexing agent solution includes a first complexing agent and a second complexing agent;

[0047] The first complexing agent includes any one of oxalic acid, sodium oxalate or potassium oxalate or a combination of at least two of them. Typical but non-limiting combinations include a combination of oxalic acid and sodium oxalate, a combination of oxalic acid and potassium oxalate, a combination of sodium oxalate and potassium oxalate, or a combination of oxalic acid, sodium oxalate and potassium oxalate.

[0048] The second complexing agent includes any one of citric acid, sodium citrate or potassium citrate or a combination of at least two thereof. Typical but non-limiting combinations include a combination of citric acid and sodium citrate, a combination of sodium citrate and potassium citrate, a combination of citric acid and potassium citrate, or a combination of citric acid, sodium citrate and potassium citrate.

[0049] The preparation method provided in the present application uses two complexing agents in a complexing agent solution, so that the first complexing agent and the second complexing agent work together to increase the specific surface area of ​​the prepared sodium ion battery precursor, facilitate the embedding of sodium ions during the sintering process of preparing the positive electrode material, and thus help improve the electrochemical performance of the positive electrode material.

[0050] The addition of complexing agent solution can adjust the formation rate and morphology of the precipitate during the coprecipitation reaction. When the concentration of the complexing agent in the complexing agent solution is too low or too high, it is not conducive to increasing the specific surface area of ​​the final sodium ion battery precursor.

[0051] In some embodiments, the concentration of the first complexing agent in the complexing agent solution is 3-12 wt%, for example, 3 wt%, 5 wt%, 6 wt%, 8 wt%, 10 wt% or 12 wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0052] In some embodiments, the concentration of the second complexing agent in the complexing agent solution is 3-12 wt%, for example, 3 wt%, 5 wt%, 6 wt%, 8 wt%, 10 wt% or 12 wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0053] In some embodiments, the total concentration of the complexing agent in the complexing agent solution is 10-20wt%, for example, it can be 10wt%, 12wt%, 15wt%, 16wt%, 18wt% or 20wt%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0054] In some embodiments, the ternary mixed salt solution is an iron-copper-manganese ternary mixed salt solution.

[0055] This application does not further limit the concentrations of ferrous salt, copper salt and manganese salt in the iron-copper-manganese ternary mixed salt solution, as long as the composition of the final sodium ion battery precursor meets the process requirements.

[0056] In some embodiments, the ferrous salt in the iron-copper-manganese ternary mixed salt solution includes ferrous sulfate and / or ferrous nitrate.

[0057] The copper salt in the iron-copper-manganese ternary mixed salt solution includes copper sulfate and / or copper nitrate.

[0058] The manganese salt in the iron-copper-manganese ternary mixed salt solution includes manganese sulfate and / or manganese nitrate.

[0059] In some embodiments, the total concentration of metal salts in the ternary mixed salt solution is 50-150 g / L, for example, it can be 50 g / L, 60 g / L, 80 g / L, 100 g / L, 120 g / L or 150 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0060] In some embodiments, the feed rate of the ternary mixed salt solution is 6-10 L / h, for example, 6 L / h, 7 L / h, 8 L / h, 9 L / h or 10 L / h, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0061] This application does not limit the feeding rate of the precipitant solution and the complexing agent solution, as long as the coprecipitation reaction can meet the process requirements.

[0062] In some embodiments, the precipitant solution comprises a sodium hydroxide solution having a concentration of 20-50 wt %.

[0063] The concentration of the sodium hydroxide solution is 20-50wt%, for example, can be 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, but is not limited to the enumerated numerical value, and other unenumerated numerical values ​​within the numerical range are equally applicable.

[0064] In some embodiments, the temperature of the base liquid is 30-80°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0065] In some embodiments, the pH value of the base solution is 10-12, for example, it can be 10, 10.5, 11, 11.5 or 12, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0066] In the present application, the pH value of the base liquid is adjusted by sodium hydroxide solution.

[0067] In some embodiments, the concentration of the complexing agent in the base solution is 1-10 g / L, for example, 1 g / L, 3 g / L, 5 g / L, 8 g / L or 10 g / L, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0068] In some embodiments, the complexing agent in the base solution includes a third complexing agent and a fourth complexing agent.

[0069] In some embodiments, the third complexing agent includes any one of oxalic acid, sodium oxalate or potassium oxalate, or a combination of at least two of them. Typical but non-limiting combinations include a combination of oxalic acid and sodium oxalate, a combination of oxalic acid and potassium oxalate, a combination of sodium oxalate and potassium oxalate, or a combination of oxalic acid, sodium oxalate and potassium oxalate.

[0070] In some embodiments, the fourth complexing agent includes any one of citric acid, sodium citrate or potassium citrate, or a combination of at least two of them. Typical but non-limiting combinations include a combination of citric acid and sodium citrate, a combination of sodium citrate and potassium citrate, a combination of citric acid and potassium citrate, or a combination of citric acid, sodium citrate and potassium citrate.

[0071] In some embodiments, the coprecipitation reaction is carried out under stirring conditions, and the stirring speed is 200-400 r / min, for example, it can be 200 r / min, 250 r / min, 300 r / min, 350 r / min or 400 r / min, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0072] In some embodiments, during the coprecipitation reaction, the temperature of the reaction system is 30-80°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C or 80°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0073] In some embodiments, during the coprecipitation reaction, the pH value of the reaction system is 9-11, for example, 9, 9.5, 10, 10.5 or 11, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0074] In some embodiments, during the coprecipitation reaction, the complexing agent concentration of the reaction system is 1-10 g / L, for example, it can be 1 g / L, 3 g / L, 5 g / L, 6 g / L, 8 g / L or 10 g / L, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0075] In some embodiments, the coprecipitation reaction is carried out under a protective atmosphere.

[0076] The gas used in the protective atmosphere includes but is not limited to nitrogen and / or argon.

[0077] In some embodiments, the target particle size is a particle size D50 of 6-8 μm, for example, 6 μm, 6.5 μm, 7 μm, 7.5 μm or 8 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0078] The embodiments of the present application provide a sodium ion battery precursor, which is prepared by the preparation method provided in the embodiments.

[0079] The present invention provides a method for preparing a positive electrode material, which comprises the following steps:

[0080] A sodium source and a sodium ion battery precursor are mixed and sintered in an oxygen atmosphere to obtain the positive electrode material.

[0081] In some embodiments, the sodium source includes but is not limited to sodium carbonate.

[0082] In some embodiments, the sintering temperature is 800-1400° C., for example, 800° C., 1000° C., 1200° C., or 1400° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0083] In some embodiments, the sintering time is 10-25 hours, for example, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, 21 hours or 25 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0084] The embodiments of the present application provide a positive electrode material, which is prepared by the preparation method in the embodiments.

[0085] An embodiment of the present application provides a battery, which includes a positive electrode material.

[0086] Example 1

[0087] This embodiment provides a method for preparing a sodium ion battery precursor, the preparation method comprising the following steps:

[0088] Under a nitrogen atmosphere, a ternary mixed salt solution of iron, copper and manganese with a concentration of 100 g / L, a precipitant solution with a concentration of 35 wt% and a complexing agent solution with a concentration of 15 wt% were simultaneously introduced into the bottom liquid, and a coprecipitation reaction was carried out under stirring conditions of 300 r / min; when the particle size reached the target particle size D50 of 7 μm, the feeding was stopped and the reaction was continued until the material reaction was complete; solid-liquid separation was performed to obtain the sodium ion battery precursor Cu 0.2 Fe 0.35 Mn 0.45 (OH)2;

[0089] The feeding rate of the iron, copper and manganese ternary mixed salt solution is 8 L / h;

[0090] The complexing agent in the complexing agent solution includes a first complexing agent oxalic acid and a second complexing agent sodium citrate; the concentration of oxalic acid in the complexing agent solution is 7.5wt%, and the concentration of sodium citrate is 7.5wt%;

[0091] The temperature of the base solution is 50° C. and the pH value is 11; the concentration of the complexing agent in the base solution is 5 g / L;

[0092] The complexing agent in the base solution includes a third complexing agent oxalic acid and a fourth complexing agent sodium citrate, the concentration of oxalic acid in the base solution is 2.5 g / L, and the concentration of sodium citrate is 2.5 g / L;

[0093] During the coprecipitation reaction, the temperature of the reaction system is 50° C. and the pH value is 10; during the coprecipitation reaction, the total concentration of the complexing agent in the reaction system is 5 g / L.

[0094] The SEM image of the sodium ion battery precursor obtained in this example is shown in FIG1 .

[0095] Example 2

[0096] This embodiment provides a method for preparing a sodium ion battery precursor, the preparation method comprising the following steps:

[0097] Under a nitrogen atmosphere, a 50 g / L iron, copper and manganese ternary mixed salt solution, a 20 wt% precipitant solution and a 10 wt% complexing agent solution were simultaneously introduced into the bottom liquid, and a coprecipitation reaction was carried out under stirring conditions of 200 r / min; when the particle size reached the target particle size D50 of 6 μm, the feeding was stopped and the reaction was continued until the material reaction was complete; solid-liquid separation was performed to obtain the sodium ion battery precursor Cu 0.2 Fe 0.35 Mn 0.45 (OH)2;

[0098] The feeding rate of the iron, copper and manganese ternary mixed salt solution is 6L / h;

[0099] The complexing agent in the complexing agent solution includes a first complexing agent oxalic acid and a second complexing agent sodium citrate; the concentration of oxalic acid in the complexing agent solution is 5wt%, and the concentration of sodium citrate is 5wt%;

[0100] The temperature of the base solution is 30° C. and the pH value is 10; the concentration of the complexing agent in the base solution is 1 g / L;

[0101] The complexing agent in the base solution includes a third complexing agent oxalic acid and a fourth complexing agent sodium citrate, the concentration of oxalic acid in the base solution is 0.5 g / L, and the concentration of sodium citrate is 0.5 g / L;

[0102] During the coprecipitation reaction, the temperature of the reaction system is 30° C. and the pH value is 9; during the coprecipitation reaction, the total concentration of the complexing agent in the reaction system is 1 g / L.

[0103] Example 3

[0104] This embodiment provides a method for preparing a sodium ion battery precursor, the preparation method comprising the following steps:

[0105] Under a nitrogen atmosphere, a ternary mixed salt solution of iron, copper and manganese with a concentration of 150 g / L, a precipitant solution with a concentration of 50 wt% and a complexing agent solution with a concentration of 20 wt% are simultaneously introduced into the base liquid, and a coprecipitation reaction is carried out under stirring conditions of 400 r / min; when the particle size reaches the target particle size D50 of 8 μm, the feeding is stopped and the reaction is continued until the material reaction is complete; solid-liquid separation is performed to obtain the sodium ion battery precursor Cu 0.2 Fe 0.35 Mn 0.45 (OH)2;

[0106] The feeding rate of the iron, copper and manganese ternary mixed salt solution is 10 L / h;

[0107] The complexing agent in the complexing agent solution includes a first complexing agent oxalic acid and a second complexing agent sodium citrate; the concentration of oxalic acid in the complexing agent solution is 10wt%, and the concentration of sodium citrate is 10wt%;

[0108] The temperature of the base solution is 80° C. and the pH value is 12; the concentration of the complexing agent in the base solution is 10 g / L;

[0109] The complexing agent in the base solution includes a third complexing agent oxalic acid and a fourth complexing agent sodium citrate, the concentration of oxalic acid in the base solution is 5g / L, and the concentration of sodium citrate is 5g / L;

[0110] During the coprecipitation reaction, the temperature of the reaction system is 80° C. and the pH value is 11; during the coprecipitation reaction, the total concentration of the complexing agent in the reaction system is 10 g / L.

[0111] Example 4

[0112] This embodiment provides a method for preparing a sodium ion battery precursor, the preparation method comprising the following steps:

[0113] Under a nitrogen atmosphere, a ternary mixed salt solution of iron, copper and manganese with a concentration of 100 g / L, a precipitant solution with a concentration of 35 wt% and a complexing agent solution with a concentration of 6 wt% were simultaneously introduced into the bottom liquid, and a coprecipitation reaction was carried out under stirring conditions of 300 r / min; when the particle size reached the target particle size D50 of 7 μm, the feeding was stopped and the reaction was continued until the material reaction was complete; solid-liquid separation was performed to obtain the sodium ion battery precursor Cu 0.2 Fe 0.35 Mn 0.45 (OH)2;

[0114] The feeding rate of the iron, copper and manganese ternary mixed salt solution is 8 L / h;

[0115] The complexing agent in the complexing agent solution includes a first complexing agent oxalic acid and a second complexing agent sodium citrate; the concentration of oxalic acid in the complexing agent solution is 3wt%, and the concentration of sodium citrate is 3wt%;

[0116] The temperature of the base solution is 50° C. and the pH value is 11; the concentration of the complexing agent in the base solution is 5 g / L;

[0117] The complexing agent in the base solution includes a third complexing agent oxalic acid and a fourth complexing agent sodium citrate, the concentration of oxalic acid in the base solution is 2.5 g / L, and the concentration of sodium citrate is 2.5 g / L;

[0118] During the coprecipitation reaction, the temperature of the reaction system is 50° C. and the pH value is 10; during the coprecipitation reaction, the total concentration of the complexing agent in the reaction system is 5 g / L.

[0119] Example 5

[0120] This embodiment provides a method for preparing a sodium ion battery precursor, the preparation method comprising the following steps:

[0121] Under a nitrogen atmosphere, a ternary mixed salt solution of iron, copper and manganese with a concentration of 100 g / L, a precipitant solution with a concentration of 35 wt% and a complexing agent solution with a concentration of 24 wt% were simultaneously introduced into the bottom liquid, and a coprecipitation reaction was carried out under stirring conditions of 300 r / min; when the particle size reached the target particle size D50 of 7 μm, the feeding was stopped and the reaction was continued until the material reaction was complete; solid-liquid separation was performed to obtain the sodium ion battery precursor Cu 0.2 Fe 0.35 Mn 0.45 (OH)2;

[0122] The feeding rate of the iron, copper and manganese ternary mixed salt solution is 8 L / h;

[0123] The complexing agent in the complexing agent solution includes a first complexing agent oxalic acid and a second complexing agent sodium citrate; the concentration of oxalic acid in the complexing agent solution is 12wt%, and the concentration of sodium citrate is 12wt%;

[0124] The temperature of the base solution is 50° C. and the pH value is 11; the concentration of the complexing agent in the base solution is 5 g / L;

[0125] The complexing agent in the base solution includes a third complexing agent oxalic acid and a fourth complexing agent sodium citrate, the concentration of oxalic acid in the base solution is 2.5 g / L, and the concentration of sodium citrate is 2.5 g / L;

[0126] During the coprecipitation reaction, the temperature of the reaction system is 50° C. and the pH value is 10; during the coprecipitation reaction, the total concentration of the complexing agent in the reaction system is 5 g / L.

[0127] Example 6

[0128] This embodiment provides a method for preparing a sodium ion battery precursor, which is the same as Example 1 except that the first complexing agent and the third complexing agent are replaced by sodium oxalate in equal amounts, and the second complexing agent and the fourth complexing agent are replaced by citric acid in equal amounts.

[0129] Example 7

[0130] This embodiment provides a method for preparing a sodium ion battery precursor. Except for changing the flow rate of the complexing agent solution so that the total concentration of the complexing agent in the reaction system during the coprecipitation reaction is 0.8 g / L, the rest is the same as Example 1.

[0131] Example 8

[0132] This embodiment provides a method for preparing a sodium ion battery precursor. Except for changing the flow rate of the complexing agent solution so that the total concentration of the complexing agent in the reaction system during the coprecipitation reaction is 11 g / L, the rest is the same as Example 1.

[0133] Comparative Example 1

[0134] This comparative example provides a method for preparing a sodium ion battery precursor, which is the same as Example 1 except that the first complexing agent and the third complexing agent are replaced by lactic acid in equal amounts.

[0135] Comparative Example 2

[0136] This comparative example provides a method for preparing a sodium ion battery precursor, which is the same as Example 1 except that the mass of the second complexing agent and the fourth complexing agent is replaced by lactic acid.

[0137] Comparative Example 3

[0138] This comparative example provides a method for preparing a sodium ion battery precursor, which is the same as Example 1 except that the first complexing agent and the third complexing agent are replaced by acetic acid in equal amounts.

[0139] Comparative Example 4

[0140] This comparative example provides a method for preparing a sodium ion battery precursor, which is the same as Example 1 except that the mass of the second complexing agent and the fourth complexing agent is replaced by acetic acid.

[0141] Comparative Example 5

[0142] This comparative example provides a method for preparing a sodium ion battery precursor, which is the same as Example 1 except that the first complexing agent and the third complexing agent are replaced by sodium citrate in equal amounts.

[0143] Comparative Example 6

[0144] This comparative example provides a method for preparing a sodium ion battery precursor, which is the same as Example 1 except that the mass of the second complexing agent and the fourth complexing agent is replaced by oxalic acid.

[0145] Performance Characterization

[0146] The specific surface area of ​​the sodium ion battery precursors obtained in Examples 1-8 and Comparative Examples 1-6 was tested. The testing method was as follows: 1 g of sample was subjected to a BET test using a BSD-660 instrument from Best. The results are shown in Table 1.

[0147] Table 1

[0148] As can be seen from Table 1, the concentration of the complexing agent solution used in Example 4 of the present application is relatively low. Although the reaction conditions are adjusted to make the complexing agent concentration during the coprecipitation reaction equivalent to that in Example 1, the low concentration of the complexing agent solution will cause many metal ions to precipitate directly before being complexed, thereby resulting in poor crystallinity of the precursor and a low tap density; the concentration of the complexing agent solution used in Example 5 of the present application is relatively high. Although the reaction conditions are adjusted to make the complexing agent concentration during the coprecipitation reaction equivalent to that in Example 1, the high concentration of the complexing agent solution will result in slow particle growth and coarse primary particles, which is also not conducive to an increase in specific surface area.

[0149] The positive electrode material was prepared using the sodium ion battery precursor obtained in Examples 1-8 and Comparative Examples 1-6. The preparation method was as follows: sodium carbonate and the sodium ion battery precursor were uniformly mixed by a high-speed mixer, and sintered in a tubular furnace under oxygen flow. The sintering temperature was 1000° C. and the time was 20 h to obtain the positive electrode material; the theoretical molar ratio of Na in the sodium carbonate to the sodium ion battery precursor was 1:1.

[0150] The positive electrode material prepared above was used as the main positive electrode material, and the metal sodium sheet was used as the negative electrode to assemble into CR2032 button batteries. Then, after activation for 3 cycles at a voltage of 2.0-4.3 V and a rate of 0.1 C, the batteries were cycled for 200 cycles at 2 C. The results are shown in Table 2.

[0151] Table 2

[0152] In summary, the preparation method provided in the present application uses two complexing agents in the complexing agent solution, so that the first complexing agent and the second complexing agent work together to increase the specific surface area of ​​the prepared sodium ion battery precursor, facilitate the embedding of sodium ions during the sintering process of the positive electrode material, and thus help improve the electrochemical performance of the positive electrode material.

[0153] The above description is only a specific implementation method of the present application, but the protection scope of the present application is not limited thereto. Those skilled in the art should understand that any changes or replacements that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a sodium ion battery precursor, comprising the following steps: The ternary mixed salt solution, the precipitant solution and the complexing agent solution are simultaneously introduced into the bottom liquid to perform a coprecipitation reaction; when the particle size reaches the target particle size, the feeding is stopped, and the reaction is continued until the material reaction is complete; the solid-liquid separation is performed to obtain the sodium ion battery precursor; The complexing agent in the complexing agent solution includes a first complexing agent and a second complexing agent; The first complexing agent includes any one of oxalic acid, sodium oxalate or potassium oxalate or a combination of at least two thereof; The second complexing agent includes any one of citric acid, sodium citrate or potassium citrate, or a combination of at least two of them.

2. The preparation method according to claim 1, in, The concentration of the first complexing agent in the complexing agent solution is 3-12 wt %; Optionally, the concentration of the second complexing agent in the complexing agent solution is 3-12 wt %; Optionally, the total concentration of the complexing agent in the complexing agent solution is 10-20 wt %.

3. The preparation method according to claim 1 or 2, in, The ternary mixed salt solution is an iron, copper and manganese mixed salt solution; Optionally, the total concentration of metal salts in the ternary mixed salt solution is 50-150 g / L; Optionally, the feed rate of the ternary mixed salt solution is 6-10 L / h.

4. The preparation method according to any one of claims 1 to 3, in, The precipitant solution includes a sodium hydroxide solution with a concentration of 20-50 wt%.

5. The preparation method according to any one of claims 1 to 4, in, The temperature of the base liquid is 30-80°C; Optionally, the pH value of the base solution is 10-12; Optionally, the concentration of the complexing agent in the base solution is 1-10 g / L; Optionally, the complexing agent in the base solution includes a third complexing agent and a fourth complexing agent; Optionally, the third complexing agent includes any one of oxalic acid, sodium oxalate or potassium oxalate, or a combination of at least two thereof; Optionally, the fourth complexing agent includes any one of citric acid, sodium citrate or potassium citrate, or a combination of at least two of them.

6. The preparation method according to any one of claims 1 to 5, in, The coprecipitation reaction is carried out under stirring conditions at a speed of 200-400 r / min; Optionally, during the coprecipitation reaction, the temperature of the reaction system is 30-80°C; Optionally, during the coprecipitation reaction, the pH value of the reaction system is 9-11; Optionally, during the coprecipitation reaction, the concentration of the complexing agent in the reaction system is 1-10 g / L; Optionally, the coprecipitation reaction is carried out under a protective atmosphere; Optionally, the target particle size is a particle size D50 of 6-8 μm.

7. A sodium ion battery precursor prepared by the preparation method according to any one of claims 1 to 6.

8. A method for preparing a positive electrode material, comprising the following steps: A sodium source is mixed with the sodium ion battery precursor according to claim 7, and sintered in an oxygen atmosphere to obtain the positive electrode material.

9. A positive electrode material prepared by the preparation method according to claim 8.

10. A battery comprising the positive electrode material according to claim 9.

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