Copper-containing sodium-ion battery positive electrode material precursor, and preparation method therefor and use thereof

Abstract

A copper-containing sodium-ion battery positive electrode material precursor, and a preparation method therefor and the use thereof. The copper-containing sodium-ion battery positive electrode material precursor is of a core-shell structure which comprises an inner core and a multi-layer shell coating the surface of the inner core, wherein the inner core is My(OH)2, 0<y<1, and M being a metallic element other than copper; and the multi-layer shell is composed of Cu(OH)2 layers and My(OH)2 layers, which are sequentially and alternately stacked in the direction away from the inner core, the outermost layer of the multi-layer shell being a Cu(OH)2 layer. The designed precursor can achieve uniform distribution of Cu in the bulk phase of the precursor, thereby reducing the phenomenon of non-uniform diffusion, and therefore a copper-containing sodium-ion battery positive electrode material prepared therefrom has better performance. Moreover, the preparation method for the structure effectively avoids the problem of the co-precipitation of Cu ions and other metal ions being difficult, solves the problems of a low Cu precipitation rate and Cu ion loss under high-ammonia conditions, enables the utilization rate of metal ions to reach 100%, and solves related problems at an industrialization end.

Description

A copper-sodium-containing cathode material precursor and its preparation method and application Technical Field

[0001] The present disclosure belongs to the technical field of sodium ion battery materials, and particularly relates to a copper-sodium cathode material precursor, a preparation method thereof, and applications thereof. Background Art

[0002] The development of lithium-ion batteries has been significantly constrained by limited lithium resources. Global lithium reserves are extremely limited, and China relies on imports for 90% of its lithium resources. This puts China at a disadvantage in energy development and makes it vulnerable to control by other overseas resources. Compared to lithium, sodium-ion batteries have more widely distributed resources.

[0003] Common cathode materials for sodium-ion batteries include Prussian white, phosphate polyanions, and multi-component layered oxides. Multi-component layered oxides have shown promising potential as cathode materials for sodium-ion batteries, offering advantages such as ideal specific capacity, ease of synthesis, and cycle stability, and have been widely researched and developed.

[0004] Layered sodium oxide cathode materials are composed of many metal ions, which have good coordination and complementary effects among each other. Some variable valence metal ions, such as Cu ions, improve the air stability of the material; some metal ions can effectively inhibit the phase change during the charge and discharge process; and some act as a structural skeleton to improve the cycle stability of the material. However, for copper-based multi-element precursors, due to the K SP The difference from other ions leads to inconsistent precipitation rates, which in turn causes segregation and makes uniform precipitation difficult, which seriously affects the performance and industrialization of synthetic materials.

[0005] Therefore, how to solve the problem of the difficulty of co-precipitation of Cu ions and other metal ions in the precursor of copper-sodium cathode materials is one of the current research focuses.

[0006] Summary of the Invention

[0007] 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.

[0008] In view of the deficiencies of the prior art, the purpose of the present disclosure is to provide a copper-containing sodium-ion battery cathode material precursor, its preparation method and application. The present disclosure designs a copper-containing sodium-ion battery cathode material precursor with a core-shell structure, which can make Cu evenly distributed in the precursor matrix, reduce the phenomenon of uneven diffusion, and make the performance of the prepared copper-containing sodium-ion battery cathode material more excellent. Moreover, the preparation method of this structure effectively avoids the problem that Cu ions are difficult to co-precipitate with other metal ions, solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, enables the utilization rate of metal ions to reach 100%, and solves the related problems at the industrialization end.

[0009] To achieve this purpose, the present disclosure adopts the following technical solutions:

[0010] In the first aspect, the present disclosure provides a copper-containing sodium-ion battery cathode material precursor, the copper-containing sodium-ion battery cathode material precursor has a core-shell structure, and the core-shell structure includes an inner core and multiple outer shells coated on the surface of the inner core;

[0011] The inner core is M y (OH)2, 0 < y < 1, and M is a metal element other than copper;

[0012] The multiple outer shells are Cu(OH)2 layers and M y (OH)2 layers alternately stacked in sequence along the direction away from the inner core, and the outermost layer of the multiple outer shells is a Cu(OH)2 layer.

[0013] The present disclosure designs a copper-containing sodium-ion battery cathode material precursor with a core-shell structure, which can make Cu evenly distributed in the precursor matrix, reduce the phenomenon of uneven diffusion, and make the performance of the prepared copper-containing sodium-ion battery cathode material more excellent. Moreover, the preparation method of this structure effectively avoids the problem that Cu ions are difficult to co-precipitate with other metal ions, solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, enables the utilization rate of metal ions to reach 100%, and solves the related problems at the industrialization end.

[0014] In the present disclosure,示例性, the chemical structural formula of the copper-containing sodium-ion battery cathode material precursor is M y1 (OH)2@Cu(OH)2@M y2 (OH)2@Cu(OH)2, as shown in Figure 1.

[0015] In the present disclosure, 0 < y < 1, for example, it can be 0.2, 0.4, 0.6 or 0.8, etc.

[0016] As an optional technical solution of the present disclosure, M includes any one or a combination of at least two of Li, K, Al, Ti, Cr, Mn, Fe, Co, Ni, Zn, Mg, Sn, Zr, Mo, Nb, Y, W, In or Ge.

[0017] In the present disclosure, although the Ksp of the above-mentioned types of metal elements and Cu element are quite different, the multi-level-graded core-shell structure of the copper-sodium cathode material precursor provided by the present disclosure solves the problems of inconsistent precipitation rate and uneven precipitation, and avoids the problem that Cu ions and other metal ions are difficult to precipitate together.

[0018] In one embodiment, the particle size of the copper-sodium cathode material precursor is: 10 μm≤D50≤20 μm, for example, it can be 10 μm, 15 μm, 18 μm or 20 μm.

[0019] In the present disclosure, the copper-sodium cathode material precursor with a particle size D50 of 10-20 μm can effectively control the particle size, core-shell size and the number of shell layers.

[0020] In one embodiment, the multi-layer shell has at least 3 layers, for example, 3 layers, 5 layers, 10 layers, 15 layers, 20 layers, 25 layers or 30 layers, etc., and can be 3-10 layers.

[0021] In a second aspect, the present disclosure provides a method for preparing a copper-sodium cathode material precursor as described in the first aspect, the preparation method comprising the following steps:

[0022] (1) Prepare M metal liquid and Cu metal liquid respectively;

[0023] (2) introducing the M metal liquid into the reactor containing the bottom liquid to carry out a nucleation reaction. When the particle size D50 of the particles reaches a first increment, the introduction of the M metal liquid is stopped, and the Cu metal liquid is introduced into the reactor containing the bottom liquid to carry out a shelling reaction. When the particle size D50 of the particles reaches a second increment, the introduction of the Cu metal liquid is stopped;

[0024] (3) Repeat step (2) until the core-shell structure of the copper-sodium cathode material precursor is synthesized.

[0025] The preparation method provided by the present disclosure effectively avoids the problems of uneven distribution of numerous metal elements in the precursor, difficulty in uniform precipitation, and easy segregation. The preparation method can effectively control the physical and chemical data of the precursor, such as morphology, particle size, primary particles, secondary particles, elemental composition, specific surface area, tap compaction, moisture, sphericity and compactness; at the same time, it can also effectively control the core-shell size and thickness to obtain high-performance precursor materials.

[0026] The preparation method provided by the present disclosure solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, so that the utilization rate of metal ions reaches 100%, and solves related problems at the industrial end.

[0027] In the present disclosure, the core of the precursor is M y (OH)2, the precursor of this structure helps to control the sphericity and morphology of the core and effectively distribute copper between the layers of the shell.

[0028] In one embodiment, the M metal liquid includes any one or a combination of at least two of an M-containing oxide, an M-containing chloride, an M-containing sulfate, an M-containing nitrate, an M-containing oxalate, an M-containing citrate, an M-containing carbonate or an M-containing acetate.

[0029] In one embodiment, the Cu metal liquid includes any one or a combination of at least two of Cu-containing oxides, Cu-containing chlorides, Cu-containing sulfates, Cu-containing nitrates, Cu-containing oxalates, Cu-containing citrates, Cu-containing carbonates, or Cu-containing acetates.

[0030] In one embodiment, the concentration of the M metal liquid is 0.1-2.5 mol / L, for example, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L or 2.5 mol / L, and can further be 1.7-2 mol / L.

[0031] In the present disclosure, if the concentration of the M metal liquid is too low, the supersaturation of the M metal liquid is too low, the effective collision reaction is slow, the growth is slow, and the reaction time to reach the desired particle size is long; if the concentration of the M metal liquid is too high, the reaction is too fast, the growth is slightly faster, which is not conducive to effective short-term control of the particle size.

[0032] In one embodiment, the concentration of the Cu metal liquid is 0.1-1.1 mol / L, for example, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.02 mol / L, 1.04 mol / L, 1.06 mol / L, 1.08 mol / L or 1.1 mol / L.

[0033] In the present disclosure, if the concentration of the Cu metal liquid is too low, the supersaturation level will be too low when the Cu metal liquid enters the reaction system, resulting in a slow reaction process and a long reaction time.

[0034] As an optional technical solution of the present disclosure, during the process of introducing the M metal liquid in step (2), ammonia water and liquid alkali are also introduced.

[0035] In the present disclosure, the purpose of introducing ammonia water and liquid alkali is: adding ammonia water can effectively control the sphericity and compactness, the shape of primary particles, and effectively control the precipitation rate between various metal ions; adding alkali solution can effectively regulate the pH value and act as a precipitant.

[0036] In one embodiment, when the nucleation reaction in step (2) is carried out, the pH value of the reaction solution is 8-13, for example, it can be 8, 9, 10, 11, 11.2, 11.4, 11.6, 11.8 or 12, and can further be 11-12.

[0037] In the present disclosure, the pH value of the reaction solution during the nucleation reaction is 8-13, which can effectively increase the number of nuclei, increase supersaturation, and increase OH - concentration, increase the metal ion and OH - Combination probability, thus producing more small particles.

[0038] In one embodiment, the flow rate of the M metal liquid in step (2) is 5-20 L / h, for example, it can be 5 L / h, 10 L / h, 15 L / h, 16 L / h, 17 L / h, 18 L / h, 19 L / h or 20 L / h, etc.

[0039] In the present disclosure, the flow rate of the M metal liquid is 5-20 L / h, which can increase the production capacity and reduce the reaction residence time.

[0040] In one embodiment, when the nucleation reaction in step (2) is carried out, the stirring frequency of the reaction solution is 30-60 Hz, for example, it can be 30 Hz, 40 Hz, 50 Hz, 55 Hz, 56 Hz, 57 Hz, 58 Hz, 59 Hz or 60 Hz, and can further be 55-60 Hz.

[0041] In the present disclosure, the stirring frequency of the reaction solution during the nucleation reaction is preferably 55-60 Hz, which can increase the number of nuclei and produce small particles.

[0042] As an optional technical solution of the present disclosure, during the process of introducing the Cu metal liquid in step (2), ammonia water and liquid alkali are also introduced.

[0043] In the present disclosure, the purpose of introducing ammonia water and liquid alkali is that the addition of ammonia water can effectively control the sphericity and compactness, the shape of the primary particles, and effectively control the precipitation rate between the various metal ions; the addition of alkali solution can effectively regulate the pH value and act as a precipitant.

[0044] In one embodiment, during the shell-forming reaction in step (2), the pH value of the reaction solution is 9-12, for example, 9, 9.5, 10, 10.5, 11 or 12.

[0045] In the present disclosure, the pH value of the reaction solution during the shell formation reaction is 9-12, which can increase the growth rate. Low pH is mainly for growth, which reduces the number of nuclei and controls small particles.

[0046] In one embodiment, the pH value of the reaction solution during the shell formation reaction is lower than the pH value of the reaction solution during the nucleation reaction.

[0047] In one embodiment, the flow rate of the Cu metal liquid in step (2) is 2-15 L / h, for example, it can be 2 L / h, 5 L / h, 10 L / h, 11 L / h, 12 L / h, 13 L / h, 14 L / h or 15 L / h, and can further be 10-15 L / h.

[0048] In the present disclosure, the preferred flow rate of the Cu metal liquid is 10-15 L / h, which can increase the growth and control the shell structure.

[0049] In one embodiment, during the shell-forming reaction in step (2), the stirring frequency of the reaction solution is 30-55 Hz, for example, 30 Hz, 35 Hz, 40 Hz, 45 Hz, 50 Hz or 55 Hz.

[0050] In the present disclosure, the stirring frequency of the reaction liquid during the shell formation reaction is 30-55 Hz, which can reduce the shear force of stirring and is conducive to the structural growth of the shell. Stirring too fast can easily break up large particles and cause secondary nucleation.

[0051] In one embodiment, in step (2), the first increment is: the particle size D50 increment of the particles is 2-10 μm, for example, it can be 2 μm, 4 μm, 6 μm or 8 μm.

[0052] In the present disclosure, the first increment: the particle size D50 increment of the particles is 2-10 μm, which is conducive to the nucleation reaction of the copper-sodium cathode material precursor to obtain an inner core with a suitable particle size.

[0053] In one embodiment, the second increment in step (2): the particle size D50 increment of the particles is 1-5 μm, for example, 1 μm, 3 μm or 5 μm.

[0054] In the present disclosure, the second increment: the particle size D50 increment of the particles is 1-5 μm, which is conducive to the shell formation reaction of the copper-sodium cathode material precursor to obtain a shell layer with appropriate thickness.

[0055] As an optional technical solution of the present disclosure, the preparation method of the base liquid includes:

[0056] Water and a pH regulator are added to the reaction kettle and stirred to obtain a base liquid with a pH value of 8-13.

[0057] In the present disclosure, the purpose of preparing a base solution with a pH value of 8-13 is to conduct experiments according to experimental requirements and effectively control the reaction.

[0058] In one embodiment, the pH adjuster is alkali solution.

[0059] In one embodiment, the alkaline solution comprises aqueous ammonia.

[0060] In one embodiment, the concentration of the ammonia water is 0-6 g / L, for example, 0, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L.

[0061] In one embodiment, the working temperature of the base liquid is 30-85°C, for example, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 85°C, and can further be 40-85°C.

[0062] In the present disclosure, the working temperature of the base liquid is preferably 40-85° C., and the working temperature of the base liquid can be adjusted according to actual needs.

[0063] In one embodiment, nitrogen is introduced during the stirring process.

[0064] In the present disclosure, the purpose of introducing nitrogen during the stirring process is to prevent the material from being oxidized during the reaction.

[0065] In one embodiment, the stirring frequency during the stirring process is 30-60 Hz, for example, 30 Hz, 40 Hz, 50 Hz or 60 Hz.

[0066] In the present disclosure, the base liquid preparation method adopts a stirring frequency of 30-60 Hz for stirring, which can make the base liquid disperse more evenly and fully, and the stirring frequency can be adjusted according to actual needs.

[0067] As an optional technical solution of the present disclosure, the preparation method includes the following steps:

[0068] (I) preparing a metal liquid M with a concentration of 0.1-2.5 mol / L according to a certain molar ratio;

[0069] Prepare a Cu metal liquid with a concentration of 0.1-1.1 mol / L according to a certain molar ratio;

[0070] (II) preparing a bottom solution for the reactor: adding water to the reactor and heating the reactor to 30-85° C., then adding a pH adjuster and stirring the reactor with nitrogen at a frequency of 30-60 Hz to obtain a bottom solution with a pH of 8-13;

[0071] Wherein, the pH adjusting agent includes alkali solution;

[0072] (Ⅲ) Introduce M metal solution, ammonia water and liquid alkali with a flow rate of 5 - 20 L / h into the reactor containing the bottom liquid, and conduct a nucleation reaction under the stirring condition with a stirring frequency of 30 - 60 Hz. When the increment of the particle size D50 is 2 - 10 μm, stop introducing the M metal solution, and continue to introduce Cu metal solution with a flow rate of 2 - 15 L / h into the reactor containing the bottom liquid, and conduct a shell-forming reaction under the stirring condition with a stirring frequency of 30 - 55 Hz. When the increment of the particle size D50 is 1 - 5 μm, stop introducing the Cu metal solution;

[0073] (Ⅳ) Repeat step (Ⅲ) until the copper-containing sodium-ion battery cathode material precursor with a multi-level and hierarchical core-shell structure is synthesized.

[0074] In the present disclosure, adopting the above preparation method can make copper ions diffuse more easily, reduce the phenomenon of uneven diffusion, be more conducive to the efficient and rapid entry of copper ions into the bulk phase, and the distribution is more uniform; moreover, it solves the problems of uneven distribution of many metal elements in the precursor, difficult uniform precipitation, and segregation, etc., and at the same time solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, making the utilization rate of metal ions reach 100%, and solving the related problems at the industrialization end.

[0075] In the third aspect, the present disclosure provides a copper-containing sodium-ion battery cathode material, which is prepared from the copper-containing sodium-ion battery cathode material precursor described in the first aspect;

[0076] The chemical structural formula of the copper-containing sodium-ion battery cathode material is Na x M y Cu n O2, where 0.5 ≤ x ≤ 1, 0 < y < 1, 0 < n < 1, and y + n = 1.

[0077] The copper-containing sodium-ion battery cathode material prepared in the present disclosure has excellent electrochemical performance.

[0078] In the present disclosure, 0.5 ≤ x ≤ 1, for example, it can be 0.5, 0.6, 0.7, 0.8, 0.9 or 1, etc.

[0079] In the present disclosure, 0 < y < 1, for example, it can be 0.2, 0.4, 0.6 or 0.8, etc.

[0080] In the present disclosure, 0 < n < 1, for example, it can be 0.2, 0.4, 0.6 or 0.8, etc.

[0081] In the fourth aspect, the present disclosure provides a sodium-ion battery, and the positive electrode of the sodium-ion battery includes the copper-containing sodium-ion battery cathode material described in the third aspect.

[0082] The numerical range described in the present disclosure includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present disclosure no longer exhaustively lists the specific point values ​​included in the range.

[0083] Compared with the prior art, the present disclosure has the following beneficial effects:

[0084] (1) The present invention discloses a core-shell structured copper-sodium cathode material precursor, wherein the core-shell structure comprises a core and a multilayer shell coated on the surface of the core, and the multilayer shell is a Cu(OH)2 layer and a M2 layer alternately stacked in a direction away from the core. y (OH)2 layer, the outermost layer of the multi-layer shell is a Cu(OH)2 layer. This structure can make Cu evenly distributed in the precursor bulk, reduce the phenomenon of uneven diffusion, and make the performance of the prepared copper-sodium cathode material more excellent.

[0085] (2) The preparation method provided by the present disclosure effectively avoids the problems of uneven distribution of numerous metal elements in the precursor, difficulty in uniform precipitation, and easy segregation. The preparation method can effectively control the physical and chemical data of the precursor, such as morphology, particle size, primary particles, secondary particles, elemental composition, specific surface area, tapping, moisture, sphericity and compactness; at the same time, it can also effectively control the size and thickness of the core-shell to obtain a high-performance precursor material.

[0086] (3) The preparation method provided by the present disclosure solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, so that the utilization rate of metal ions reaches 100%, solving related problems on the industrial end.

[0087] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] 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.

[0089] FIG1 is a cross-sectional view of a copper-sodium cathode material precursor prepared in one embodiment of the present disclosure.

[0090] FIG2 is a SEM image of the copper-sodium cathode material precursor prepared in Example 1 of the present disclosure.

[0091] FIG3 is a TEM image of the copper-sodium cathode material precursor prepared in Example 1 of the present disclosure.

[0092] Figure 4 is a SEM image of the copper-containing sodium-ion battery cathode material precursor prepared in Comparative Example 1 of the present disclosure. Detailed implementation manners

[0093] The technical solutions of the present disclosure will be further described below through specific implementation manners. Those skilled in the art should understand that the embodiments are only for helping to understand the present disclosure and should not be regarded as specific limitations on the present disclosure.

[0094] Example 1

[0095] The present disclosure provides a copper-containing sodium-ion battery cathode material precursor. The copper-containing sodium-ion battery cathode material precursor has a core-shell structure, and the core-shell structure includes a core and multiple outer shells coated on the surface of the core;

[0096] The core is M y (OH)2, 0 < y < 1, M includes Ni, Mn, and Fe with a molar ratio of 0.3:0.4:0.15, and y = 0.85;

[0097] The multiple outer shells are Cu(OH)2 layers and M y (OH)2 layers alternately stacked in sequence along the direction away from the core. The outermost layer of the multiple outer shells is a Cu(OH)2 layer, and the number of layers of the multiple outer shells is 3;

[0098] The particle size D50 of the copper-containing sodium-ion battery cathode material precursor is 10 μm.

[0099] This example also provides a preparation method for the above copper-containing sodium-ion battery cathode material precursor. The preparation method includes the following steps:

[0100] (1) Prepare an M metal solution with a concentration of 1.7 mol / L according to a certain molar ratio;

[0101] Prepare a Cu metal solution with a concentration of 1.0 mol / L according to a certain molar ratio;

[0102] Among them, the M metal solution includes nickel sulfate, manganese sulfate, and ferrous sulfate. The molar ratio of nickel in nickel sulfate, manganese in manganese sulfate, and iron in ferrous sulfate is 0.3:0.4:0.15, and the Cu metal solution is a copper sulfate solution;

[0103] (2) Prepare the bottom liquid of the reaction kettle: Add 1 / 3 of the volume of the reaction kettle of water to the reaction kettle, heat the temperature of the reaction kettle to 60 °C, then add a pH regulator, and introduce nitrogen for stirring treatment. The stirring frequency is 50 Hz to obtain a bottom liquid with a pH value of 10.3;

[0104] Among them, the pH regulator is ammonia water, and the concentration of ammonia water is 4 g / L;

[0105] (3) Feed M metal solution with a flow rate of 15 L / h into the reaction kettle containing the bottom liquid, and at the same time raise the pH value of the reaction liquid to 10.3. Conduct a nucleation reaction under stirring conditions with a stirring frequency of 55 Hz. When the first increment of the particle size D50 is 3 μm, stop feeding the M metal solution, and continue to feed Cu metal solution with a flow rate of 10 L / h into the reaction kettle containing the bottom liquid. Lower the pH value to 10.2, and conduct a shell-forming reaction under stirring conditions with a stirring frequency of 40 Hz. When the second increment of the particle size D50 is 2 μm, stop feeding the Cu metal solution;

[0106] (4) Repeat step (3) until the copper-containing sodium-ion battery cathode material precursor is synthesized.

[0107] Figure 2 shows the SEM image of the copper-containing sodium-ion battery cathode material precursor prepared in this embodiment. As can be seen from the figure, the sphericity of this material is relatively good and the particle size is controllable.

[0108] Figure 3 shows the TEM image of the copper-containing sodium-ion battery cathode material precursor prepared in this embodiment. As can be seen from the figure, the material has a core-shell structure, and this structure can make Cu evenly distributed in the precursor matrix, reducing the phenomenon of uneven diffusion.

[0109] Example 2

[0110] The present disclosure provides a copper-containing sodium-ion battery cathode material precursor. The copper-containing sodium-ion battery cathode material precursor has a core-shell structure, and the core-shell structure includes a core and multiple outer shells coated on the surface of the core;

[0111] The core is M y (OH)2, 0 < y < 1, M includes Ni, Mn, and Fe with a molar ratio of 0.3:0.3:0.2, and y = 0.8;

[0112] The multiple outer shells are successively and alternately stacked along the direction away from the core, with Cu(OH)2 layers and M y (OH)2 layers. The outermost layer of the multiple outer shells is a Cu(OH)2 layer, and the number of layers of the multiple outer shells is 3 layers;

[0113] The particle size D50 of the copper-containing sodium-ion battery cathode material precursor is 10 μm.

[0114] This embodiment also provides a preparation method for the above copper-containing sodium-ion battery cathode material precursor. The preparation method includes the following steps:

[0115] (1) Prepare an M metal solution with a concentration of 2.1 mol / L according to a certain molar ratio;

[0116] Prepare a Cu metal solution with a concentration of 1.0 mol / L according to a certain molar ratio;

[0117] Among them, the M metal solution includes nickel sulfate, manganese sulfate and ferrous sulfate, and the molar ratio of nickel in nickel sulfate, manganese in manganese sulfate and iron in ferrous sulfate is 0.3:0.3:0.2. The Cu metal solution is a copper sulfate solution;

[0118] (2) Prepare the bottom liquid of the reaction kettle: Add water accounting for 1 / 3 of the volume of the reaction kettle to the reaction kettle, heat the temperature of the reaction kettle to 70 °C, then add a pH regulator, and introduce nitrogen for stirring treatment. The stirring frequency is 60 Hz to obtain a bottom liquid with a pH value of 10.0;

[0119] Among them, the pH regulator is ammonia water, and the concentration of ammonia water is 6 g / L;

[0120] (3) Introduce the M metal solution with a flow rate of 15 L / h into the reaction kettle containing the bottom liquid, and at the same time raise the pH value of the reaction solution to 10.0. Carry out a nucleation reaction under the stirring condition with a stirring frequency of 56 Hz. When the first increment of the particle size D50 is about 3 μm, stop introducing the M metal solution, and continue to introduce the Cu metal solution with a flow rate of 10 L / h into the reaction kettle containing the bottom liquid, lower the pH value to 9.8, and carry out a shell-forming reaction under the stirring condition with a stirring frequency of 47 Hz. When the second increment of the particle size D50 is 2 μm, stop introducing the Cu metal solution;

[0121] (4) Repeat step (3) until the copper-containing sodium-ion battery cathode material precursor is synthesized.

[0122] Example 3

[0123] The present disclosure provides a copper-containing sodium-ion battery cathode material precursor. The copper-containing sodium-ion battery cathode material precursor has a core-shell structure, and the core-shell structure includes a core and multiple outer shells coated on the surface of the core;

[0124] The core is M y (OH)2, 0 < y < 1, M includes Ni, Mn and Fe with a molar ratio of 0.4:0.2:0.2, and y = 0.8;

[0125] The multiple outer shells are successively and alternately stacked layers of Cu(OH)2 layers and M y (OH)2 layers along the direction away from the core. The outermost layer of the multiple outer shells is a Cu(OH)2 layer, and the number of layers of the multiple outer shells is 3 layers;

[0126] The particle size D50 of the copper-containing sodium-ion battery cathode material precursor is 15 μm.

[0127] This example also provides a preparation method for the above-mentioned copper-containing sodium-ion battery cathode material precursor. The preparation method includes the following steps:

[0128] (1) Prepare the M metal solution with a concentration of 1.8 mol / L according to a certain molar ratio.

[0129] Prepare the Cu metal solution with a concentration of 0.9 mol / L according to a certain molar ratio.

[0130] Among them, the M metal solution includes nickel sulfate, manganese sulfate and ferrous sulfate, and the molar ratio of nickel in nickel sulfate, manganese in manganese sulfate and iron in ferrous sulfate is 0.4:0.2:0.2. The Cu metal solution is copper sulfate solution.

[0131] (2) Prepare the bottom liquid of the reaction kettle: Add water accounting for 1 / 3 of the volume of the reaction kettle into the reaction kettle, heat the temperature of the reaction kettle to 70 °C, then add a pH regulator, and introduce nitrogen for stirring treatment. The stirring frequency is 60 Hz to obtain a bottom liquid with a pH value of 10.1.

[0132] Among them, the pH regulator is ammonia water, and the concentration of ammonia water is 3 g / L.

[0133] (3) Introduce the M metal solution with a flow rate of 20 L / h into the reaction kettle containing the bottom liquid, and at the same time raise the pH value of the reaction solution to 10.1. Carry out the nucleation reaction under the stirring condition with a stirring frequency of 60 Hz. When the first increment of the particle size D50 is 3 μm, stop introducing the M metal solution, and continue to introduce the Cu metal solution with a flow rate of 10 L / h into the reaction kettle containing the bottom liquid, lower the pH value to 9.8, and carry out the shell-forming reaction under the stirring condition with a stirring frequency of 45 Hz. When the second increment of the particle size D50 is 2 μm, stop introducing the Cu metal solution.

[0134] (4) Repeat step (3) until the copper-containing sodium-ion battery cathode material precursor is synthesized.

[0135] Example 4

[0136] The present disclosure provides a copper-containing sodium-ion battery cathode material precursor. The copper-containing sodium-ion battery cathode material precursor has a core-shell structure, and the core-shell structure includes a core and multiple outer shells coated on the surface of the core.

[0137] The core is M y (OH)2, 0 < y < 1, M includes Ni, Mn, Fe and Zn with a molar ratio of 0.2:0.35:0.3:0.1, and y = 0.95.

[0138] The multiple outer shells are successively and alternately stacked layers of Cu(OH)2 layers and M y (OH)2 layers along the direction away from the core. The outermost layer of the multiple outer shells is a Cu(OH)2 layer, and the number of layers of the multiple outer shells is 3 layers.

[0139] The particle size D50 of the copper-containing sodium-ion battery cathode material precursor is 15 μm.

[0140] This embodiment also provides a method for preparing the above copper-containing sodium-ion battery cathode material precursor. The preparation method includes the following steps:

[0141] (1) Prepare an M metal solution with a concentration of 2.0 mol / L according to a certain molar ratio;

[0142] Prepare a Cu metal solution with a concentration of 1.0 mol / L according to a certain molar ratio;

[0143] Among them, the M metal solution includes nickel sulfate, manganese sulfate, ferrous sulfate and zinc sulfate. The molar ratio of nickel in nickel sulfate, manganese in manganese sulfate, iron in ferrous sulfate and zinc in zinc sulfate is 0.2:0.35:0.3:0.1. The Cu metal solution is a copper sulfate solution;

[0144] (2) Prepare the bottom liquid of the reaction kettle: Add water accounting for 1 / 3 of the volume of the reaction kettle to the reaction kettle, heat the temperature of the reaction kettle to 70 °C, then add a pH regulator, and introduce nitrogen for stirring treatment. The stirring frequency is 60 Hz to obtain a bottom liquid with a pH value of 9.8;

[0145] Among them, the pH regulator is ammonia water, and the concentration of ammonia water is 2 g / L;

[0146] (3) Introduce the M metal solution with a flow rate of 16 L / h into the reaction kettle containing the bottom liquid, and at the same time raise the pH value of the reaction solution to 9.8. Perform a nucleation reaction under the stirring condition with a stirring frequency of 57 Hz. When the first increment of the particle size D50 is 3 μm, stop introducing the M metal solution, and continue to introduce the Cu metal solution with a flow rate of 10 L / h into the reaction kettle containing the bottom liquid. Lower the pH value to 9.7 and perform a shell-forming reaction under the stirring condition with a stirring frequency of 47 Hz. When the second increment of the particle size D50 is 2 μm, stop introducing the Cu metal solution;

[0147] (4) Repeat step (3) until the copper-containing sodium-ion battery cathode material precursor is synthesized.

[0148] Example 5

[0149] The present disclosure provides a copper-containing sodium-ion battery cathode material precursor. The copper-containing sodium-ion battery cathode material precursor has a core-shell structure, and the core-shell structure includes an inner core and multiple outer shells coated on the surface of the inner core;

[0150] The inner core is M y (OH)2, 0 < y < 1, M includes Ni, Mn, Fe and Zn with a molar ratio of 0.2:0.4:0.3:0.07, and y = 0.97;

[0151] The multilayer shell is a Cu(OH)2 layer and a M layer alternately stacked in a direction away from the core. y (OH)2 layer, the outermost layer of the multi-layer shell is a Cu(OH)2 layer, and the number of layers of the multi-layer shell is 3;

[0152] The particle size D50 of the copper-sodium cathode material precursor is 18 μm.

[0153] This embodiment also provides a method for preparing the above-mentioned copper-sodium cathode material precursor, the preparation method comprising the following steps:

[0154] (1) preparing a metal liquid M with a concentration of 2.0 mol / L according to a certain molar ratio;

[0155] Prepare a Cu metal liquid with a concentration of 1.0 mol / L according to a certain molar ratio;

[0156] Wherein, the M metal liquid includes manganese sulfate, manganese sulfate, ferrous sulfate and zinc sulfate, the molar ratio of nickel in nickel sulfate, manganese in manganese sulfate, iron in ferrous sulfate and zinc in zinc sulfate is 0.2:0.4:0.3:0.07, and the Cu metal liquid is copper sulfate solution;

[0157] (2) Preparation of the bottom liquid of the reactor: Add 1 / 3 of the volume of water to the reactor and heat the reactor to 65°C. Then, add a pH adjuster and introduce nitrogen gas for stirring at a frequency of 60 Hz to obtain a bottom liquid with a pH of 9.7.

[0158] The pH regulator is ammonia water, and the concentration of ammonia water is 4 g / L;

[0159] (3) introducing M metal liquid at a flow rate of 20 L / h into the reactor containing the base liquid, while raising the pH value of the reaction liquid to 9.7, and performing a nucleation reaction under a stirring condition of a stirring frequency of 60 Hz. When the first increment of the particle size D50 is 4 μm, the introduction of M metal liquid is stopped, and Cu metal liquid is continued to be introduced into the reactor containing the base liquid at a flow rate of 12 L / h, and the pH value is lowered to 9.5. A shelling reaction is performed under a stirring condition of a stirring frequency of 50 Hz. When the second increment of the particle size D50 is 2 μm, the introduction of Cu metal liquid is stopped;

[0160] (4) Repeat step (3) until the copper-sodium cathode material precursor is synthesized.

[0161] Example 6

[0162] The difference between this embodiment and embodiment 1 is that the concentration of the M metal liquid is 0.05 mol / L.

[0163] The rest of the preparation methods and parameters remained the same as in Example 1.

[0164] Example 7

[0165] The difference between this embodiment and embodiment 1 is that the concentration of the M metal liquid is 3 mol / L.

[0166] The rest of the preparation methods and parameters remained the same as in Example 1.

[0167] Example 8

[0168] The difference between this embodiment and embodiment 1 is that the concentration of the Cu metal liquid is 0.05 mol / L.

[0169] The rest of the preparation methods and parameters remained the same as in Example 1.

[0170] Example 9

[0171] The difference between this embodiment and embodiment 1 is that during the introduction of the M metal liquid in step (3), 0.5 g / L of ammonia water is also introduced.

[0172] The rest of the preparation methods and parameters remained the same as in Example 1.

[0173] Comparative Example 1

[0174] This comparative example provides a method for preparing a copper-sodium cathode material precursor, the preparation method comprising the following steps:

[0175] (1) nickel sulfate, manganese sulfate, ferrous sulfate, and copper sulfate were weighed according to the molar ratio of Ni:Mn:Fe:Cu of 0.2:0.5:0.15:0.15 to prepare a molten metal with a concentration of 2.0 mol / L;

[0176] (2) Preparation of the bottom liquid of the reactor: Add 1 / 3 of the volume of water to the reactor and heat the reactor to 70°C. Then, add a pH adjuster and introduce nitrogen gas for stirring at a frequency of 55 Hz to obtain a bottom liquid with a pH of 10.5.

[0177] The pH regulator is ammonia water, and the concentration of ammonia water is 4 g / L;

[0178] (3) introducing a metal liquid at a flow rate of 15 L / h into the reactor containing the base liquid, and at the same time raising the pH value of the metal liquid to 10.5, performing a nucleation reaction under stirring conditions of a stirring frequency of 55 Hz, and when the particle size D50 increment is 5 μm, lowering the pH value to 10.3, reducing the flow rate to 10 L / h, and performing a shelling reaction under stirring conditions of a stirring frequency of 45 Hz, until the copper-sodium cathode material precursor is obtained.

[0179] FIG4 shows an SEM image of the copper-sodium cathode material precursor prepared in this comparative example. As can be seen from the figure, the morphology is relatively poor, the sphericity is relatively poor, the particle size is inconsistent, and there is severe segregation.

[0180] Performance Testing

[0181] The copper-sodium cathode material precursor prepared in the above examples and comparative examples is made into a copper-sodium cathode material, and then made into a cathode sheet, which is assembled with a cathode sheet, a separator and an electrolyte to obtain a sodium ion battery.

[0182] The preparation method of the copper-sodium cathode material includes: mixing the precursor materials obtained corresponding to each embodiment and comparative example with a sodium source, performing a mixing process, wherein the mass ratio of Na:Me (metal elements in the precursor material) is 1.05:1, and then performing a high-temperature sintering process, the sintering temperature is 950°C, and the sintering time is 12h, to obtain the copper-sodium cathode material.

[0183] The positive electrode sheet preparation method includes: weighing the aforementioned copper-sodium positive electrode material, conductive carbon black, and vinylidene fluoride in a mass ratio of 80:10:10, and then uniformly mixing them in an N-methylpyrrolidone solution. The resulting slurry is coated on aluminum foil, vacuum-dried, and then cut and punched into positive electrode sheets with a diameter of 12 mm.

[0184] The preparation method of the sodium ion battery includes: using a metallic sodium sheet as the negative electrode, using a 1 mol / L NaPF6 / polycarbonate (PC):ethylene carbonate (EC):dimethyl carbonate (DMC) (volume ratio of 1:1:1) + 5% FEC solution as the electrolyte, and using glass fiber as the separator, and assembling it into a button battery in an argon glove box.

[0185] The electrochemical performance test of the sodium ion battery was carried out under the following test conditions: charge and discharge test was carried out in the voltage range of 1.5-4.0V and at 0.1C condition to obtain the first charge-discharge capacity and the first coulombic efficiency. The test results are shown in Table 1.

[0186] Table 1

[0187] analyze:

[0188] As can be seen from the above table, the present disclosure designs a multi-level-graded core-shell structure of a copper-sodium cathode material precursor. This structure can make Cu evenly distributed in the precursor bulk, reducing the phenomenon of uneven diffusion, and making the performance of the prepared copper-sodium cathode material more excellent.

[0189] It can be seen from Example 1 and Examples 6-8 that if the concentration of the M metal liquid or the Cu metal liquid is too low, the supersaturation is too low, which will lead to a slow reaction rate and increased growth time; if the concentration of the M metal liquid is too high, the supersaturation is too high, which will lead to faster growth and difficult to control the particle size.

[0190] It can be seen from Examples 1 and 9 that if ammonia water is introduced during the introduction of the M metal liquid, the reaction rate of the metal ions can be slowed down, resulting in a high compactness and good sphericity of the M-containing layer.

[0191] It can be seen from Example 1 and Comparative Example 1 that if the Ni, Mn, Fe, and Cu metal liquids are all mixed together and fed into the liquid at the same time, the materials will not be uniformly precipitated, and there will be a certain degree of segregation, resulting in poor sphericity and morphology of the material, which will have a certain impact on the electrical properties.

[0192] The applicant declares that the present disclosure illustrates the process method of the present disclosure through the above-mentioned embodiments, but the present disclosure is not limited to the above-mentioned process steps, that is, it does not mean that the present disclosure must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement to the present disclosure, the equivalent replacement of the raw materials selected by the present disclosure, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present disclosure. For example, the core of the copper-sodium cathode material precursor can also be Cu(OH)2, and the multi-layer shell is M alternately stacked in a direction away from the core. y (OH)2 layer and Cu(OH)2 layer, and the outermost layer of the multilayer shell is M y (OH)2 layer.

Claims

1. A copper-sodium-containing cathode material precursor, the copper-sodium-containing cathode material precursor having a core-shell structure, the core-shell structure including a core and multiple layers of outer shells coated on the surface of the core; The core is M y (OH)2, where 0 < y < 1, and M is a metal element other than copper; The multi-layered shell is composed of Cu(OH)2 layers and M y (OH)2 layers that are alternately stacked in sequence along the direction away from the core, and the outermost layer of the multi-layered shell is a Cu(OH)2 layer.

2. The copper-containing sodium-ion battery cathode material precursor according to claim 1, wherein, wherein M includes any one or a combination of at least two of Li, K, Al, Ti, Cr, Mn, Fe, Co, Ni, Zn, Mg, Sn, Zr, Mo, Nb, Y, W, In, or Ge.

3. The copper-containing sodium-ion battery cathode material precursor according to claim 1 or 2, wherein, The particle size of the copper-sodium-containing cathode material precursor: 10 μm ≤ D50 ≤ 20 μm.

4. The copper-containing sodium-ion battery cathode material precursor according to any one of claims 1-3, wherein, The number of layers of the multiple layers of outer shells is at least 3 layers, and further optionally 3 - 10 layers.

5. A preparation method of the copper-sodium-containing cathode material precursor according to any one of claims 1 - 4, comprising the following steps: (1) Prepare M metal solution and Cu metal solution respectively; (2) Introduce the M metal solution into a reaction kettle containing a bottom liquid to carry out a nucleation reaction. When the particle size D50 of the particles reaches a first increment, stop introducing the M metal solution, and introduce the Cu metal solution into the reaction kettle containing the bottom liquid to carry out a shell-forming reaction. When the particle size D50 of the particles reaches a second increment, stop introducing the Cu metal solution; (3) Repeat step (2) until the copper-sodium-containing cathode material precursor with a core-shell structure is synthesized.

6. The preparation method according to claim 5, wherein, The concentration of the M metal solution is 0.1 - 2.5 mol / L, and further optionally 1.7 - 2 mol / L.

7. The preparation method according to claim 5 or 6, wherein The concentration of the Cu metal solution is 0.1 - 1.1 mol / L.

8. The preparation method according to any one of claims 5-7, wherein, During the introduction of the M metal solution in step (2), ammonia water and liquid alkali are also introduced.

9. The preparation method according to any one of claims 5-8, wherein, When carrying out the nucleation reaction in step (2), the pH value of the reaction solution is 8 - 13.

10. The preparation method according to any one of claims 5-9, wherein, The introduction flow rate of the M metal solution in step (2) is 5 - 20 L / h.

11. The preparation method according to any one of claims 5-10, wherein, When carrying out the nucleation reaction in step (2), the stirring frequency of the reaction solution is 30 - 60 Hz.

12. The preparation method according to any one of claims 5-11, wherein, During the introduction of the Cu metal solution in step (2), ammonia water and liquid alkali are also introduced; Optionally, when carrying out the shell-forming reaction in step (2), the pH value of the reaction solution is 9 - 12; Optionally, the introduction flow rate of the Cu metal solution in step (2) is 2 - 15 L / h; Optionally, when carrying out the shell-forming reaction in step (2), the stirring frequency of the reaction solution is 30 - 55 Hz; Optionally, the first increment in step (2): the increment of the particle size D50 of the particles is 2 - 10 μm; Optionally, the second increment in step (2): the increment of the particle size D50 of the particles is 1 - 5 μm.

13. The preparation method according to any one of claims 5-12, wherein, The preparation method of the bottom liquid includes: Add water and a pH regulator to the reaction kettle and carry out stirring treatment to obtain a bottom liquid with a pH value of 8 - 13; Optionally, the working temperature of the bottom liquid is 30 - 85 °C; Optionally, nitrogen is introduced during the stirring treatment; Optionally, the stirring frequency during the stirring treatment is 30 - 60 Hz.

14. The preparation method according to any one of claims 5-13, wherein, The preparation method includes the following steps: (Ⅰ) Prepare an M metal solution with a concentration of 0.1 - 2.5 mol / L according to a certain molar ratio; Prepare a Cu metal solution with a concentration of 0.1 - 1.1 mol / L according to a certain molar ratio; (II) Prepare the bottom liquid of the reaction kettle: Add water to the reaction kettle, heat the temperature of the reaction kettle to 30 - 85 °C, then add a pH regulator, and introduce nitrogen for stirring treatment with a stirring frequency of 30 - 60 Hz to obtain a bottom liquid with a pH value of 8 - 13; Among them, the pH regulator includes an alkaline solution; (III) Introduce M metal liquid, ammonia water and liquid alkali with a flow rate of 5 - 20 L / h into the reaction kettle containing the bottom liquid, and carry out a nucleation reaction under stirring conditions with a stirring frequency of 30 - 60 Hz. When the increment of the particle size D50 is 2 - 10 μm, stop introducing the M metal liquid, and continue to introduce Cu metal liquid with a flow rate of 2 - 15 L / h into the reaction kettle containing the bottom liquid, and carry out a shell-forming reaction under stirring conditions with a stirring frequency of 30 - 55 Hz. When the increment of the particle size D50 is 1 - 5 μm, stop introducing the Cu metal liquid; (IV) Repeat step (III) until the copper-containing sodium-ion battery cathode material precursor with a multi-level and hierarchical core-shell structure is synthesized.

15. A copper-containing sodium-ion battery cathode material prepared from the copper-containing sodium-ion battery cathode material precursor according to any one of claims 1 - 4, wherein The chemical structural formula of the copper-containing sodium-based cathode material is Na x M y Cu n O2, where 0.5 ≤ x ≤ 1, 0 < y < 1, 0 < n < 1, and y + n = 1.

16. A sodium-ion battery comprising the copper-containing sodium-ion battery cathode material according to claim 15.

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