A copper-sodium cathode material precursor, its preparation method and application

Abstract

The present disclosure provides a copper-containing sodium-ion battery cathode material precursor, a preparation method thereof, and an application thereof. 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; the core is M y (OH)2, where 0 < y < 1, and M is a metal element other than copper; the multiple outer shells are 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 multiple outer shells is a Cu(OH)2 layer. The precursor designed in the present disclosure can make Cu evenly distributed in the precursor bulk phase, 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 and other metal ions are difficult to co-precipitate, solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, makes the utilization rate of metal ions reach 100%, and solves the related problems at the industrialization end.

Description

Technical Field

[0001] This disclosure belongs to the field of sodium-ion battery materials technology, specifically relating to a copper-containing sodium-ion battery cathode material precursor, its preparation method, and its application. Background Technology

[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 in a very passive position regarding energy development, making it vulnerable to resource constraints from other overseas sources. In contrast, sodium-ion batteries have widely distributed resources.

[0003] Common cathode materials for sodium-ion batteries include Prussian white, phosphate polyanionic oxides, and multi-layered oxides. Among them, multi-layered oxides have certain potential advantages as cathode materials for sodium-ion batteries, possessing ideal specific capacity, ease of synthesis, and cycle stability, and have been extensively studied and developed.

[0004] Layered sodium oxide cathode materials are composed of numerous metal ions, which exhibit good coordination and complementarity. Some variable-valence metal ions, such as Cu ions, enhance the material's air stability; others effectively suppress phase changes during charge and discharge; and still others act as a structural framework, improving the material's cycle stability. However, for copper-based multi-component precursors, due to the K+ of Cu ions... SP The difference from other ions leads to inconsistent precipitation rates, resulting in segregation and making it difficult to precipitate uniformly. This seriously affects the performance and industrialization of the synthesized materials.

[0005] Therefore, how to solve the problem of Cu ions being difficult to co-precipitate with other metal ions in copper-containing sodium cathode material precursors is one of the current research focuses. Summary of the Invention

[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0007] To address the shortcomings of existing technologies, the present disclosure aims to provide a copper-sodium cathode material precursor, its preparation method, and its applications. This disclosure designs a core-shell structured copper-sodium cathode material precursor. This structure allows for uniform distribution of Cu within the precursor bulk phase, reducing diffusion inhomogeneity and resulting in superior performance of the prepared copper-sodium cathode material. Furthermore, the preparation method of this structure effectively avoids the problem of Cu ions being difficult to co-precipitate with other metal ions, solving the issues of low Cu precipitation rate and Cu ion loss under high ammonia conditions, achieving 100% metal ion utilization, and resolving related issues in industrialization.

[0008] To achieve this goal, the present disclosure adopts the following technical solutions:

[0009] In a first aspect, the present disclosure provides a copper-containing sodium-ion battery cathode material precursor, which has a core-shell structure. The core-shell structure includes a core and multiple outer shells coated on the surface of the core;

[0010] The core is M y (OH)2, where 0 < y < 1, and M is a metal element other than copper;

[0011] The multiple outer shells are successively and alternately stacked 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.

[0012] The present disclosure designs a copper-containing sodium-ion battery cathode material precursor with a core-shell structure. This structure enables Cu to be evenly distributed within the precursor matrix, reducing the phenomenon of uneven diffusion and making 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 of difficult co-precipitation of Cu ions and other metal ions, solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, achieves a 100% utilization rate of metal ions, and solves related problems at the industrialization stage.

[0013] In the present disclosure, by way of example, 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 Figure 1 shown.

[0014] In the present disclosure, 0 < y < 1, for example, it can be 0.2, 0.4, 0.6, or 0.8, etc.

[0015] 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.

[0016] In the present disclosure, although the Ksp of the above types of metal elements and Cu element differ greatly, the multi-level and hierarchical core-shell structured copper-containing sodium-ion battery cathode material precursor provided by the present disclosure solves the problems of inconsistent precipitation rate and uneven precipitation, and avoids the problem of difficult co-precipitation of Cu ions and other metal ions.

[0017] In one embodiment, the particle size of the copper-containing sodium cathode material precursor is 10μm≤D50≤20μm, for example, it can be 10μm, 15μm, 18μm or 20μm, etc.

[0018] In this disclosure, copper-containing sodium cathode material precursors with a particle size D50 of 10-20 μm can effectively control the particle size, core-shell size, and number of shell layers.

[0019] In one embodiment, the number of layers of the multi-layer shell is at least 3, for example, it can be 3, 5, 10, 15, 20, 25 or 30 layers, etc., and can be selected as 3-10 layers.

[0020] In a second aspect, this disclosure provides a method for preparing a copper-containing sodium cathode material precursor as described in the first aspect, the method comprising the following steps:

[0021] (1) Prepare M metal liquid and Cu metal liquid respectively;

[0022] (2) The M metal liquid is introduced into the reactor containing the bottom liquid to carry out the nucleation reaction. When the particle size D50 reaches the first increment, the M metal liquid is stopped, and Cu metal liquid is introduced into the reactor containing the bottom liquid to carry out the shell formation reaction. When the particle size D50 reaches the second increment, the Cu metal liquid is stopped.

[0023] (3) Repeat step (2) until the core-shell structure of the copper-containing sodium cathode material precursor is synthesized.

[0024] The preparation method disclosed herein effectively avoids problems such as uneven distribution of numerous metal elements in the precursor, difficulty in uniform precipitation, and easy segregation. This preparation method can effectively control the physicochemical data of the precursor, such as morphology, particle size, primary particles, secondary particles, elemental composition, specific surface area, tap, 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.

[0025] The preparation method disclosed herein solves the problems of low Cu precipitation rate and Cu ion loss under high ammonia conditions, enabling 100% utilization of metal ions and resolving related issues in industrialization.

[0026] In this 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 nucleus, and enables copper to be effectively distributed between the shell layers.

[0027] In one embodiment, the liquid metal containing M includes any one or a combination of at least two of the following: oxides containing M, chlorides containing M, sulfates containing M, nitrates containing M, oxalates containing M, citrates containing M, carbonates containing M, or acetates containing M.

[0028] In one embodiment, the Cu metal liquid includes any one or a combination of at least two of the following: 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.

[0029] In one embodiment, the concentration of the M metal liquid is 0.1-2.5 mol / L, for example, it can be 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L or 2.5 mol / L, and may be further selected as 1.7-2 mol / L.

[0030] In this disclosure, if the concentration of the M metal liquid is too low, the M metal liquid will be too low in supersaturation, resulting in a slow effective collision reaction, slow growth, and a long reaction time to reach the required particle size; if the concentration of the M metal liquid is too high, the reaction will be too fast, resulting in slightly faster growth, which is not conducive to short-term effective control of particle size.

[0031] In one embodiment, the concentration of the Cu metal liquid is 0.1-1.1 mol / L, for example, it can be 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, etc.

[0032] In this disclosure, if the concentration of Cu metal liquid is too low, the supersaturation will be too low when it enters the reaction system, resulting in a slow reaction process and a long reaction time.

[0033] As an optional technical solution of this disclosure, during the process of introducing the M metal liquid in step (2), ammonia water and liquid alkali are also introduced.

[0034] In this disclosure, the purpose of introducing ammonia and liquid alkali is as follows: adding ammonia can effectively control the sphericity and compactness, the shape of primary particles, and effectively control the precipitation rate between various metal ions; adding alkali can effectively regulate the pH value and also act as a precipitant.

[0035] In one embodiment, when the nucleation reaction described 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 be further selected as 11-12.

[0036] In this 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, increasing the interaction between metal ions and OH groups. - The probability of combining increases, thus producing more small particles.

[0037] 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.

[0038] In this disclosure, the flow rate of the molten M metal is 5-20 L / h, which can increase production capacity and reduce reaction residence time.

[0039] In one embodiment, when performing the nucleation reaction described in step (2), the stirring frequency of the reaction solution is 30-60Hz, for example, it can be 30Hz, 40Hz, 50Hz, 55Hz, 56Hz, 57Hz, 58Hz, 59Hz or 60Hz, and can be further selected as 55-60Hz.

[0040] In this 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.

[0041] As an optional technical solution of this disclosure, in the process of introducing Cu metal liquid in step (2), ammonia water and liquid alkali are also introduced.

[0042] In this disclosure, the purpose of introducing ammonia and liquid alkali is to effectively control the sphericity and compactness, the shape of primary particles, and the precipitation rate between various metal ions by adding ammonia; and to effectively regulate the pH value by adding alkali solution, while also acting as a precipitant.

[0043] In one embodiment, when performing the shell-forming reaction described in step (2), the pH value of the reaction solution is 9-12, for example, it can be 9, 9.5, 10, 10.5, 11 or 12.

[0044] In this disclosure, the pH value of the reaction solution during the shell-forming reaction is 9-12, which can increase the growth rate. Low pH promotes growth, reduces the number of nuclei, and controls small particles.

[0045] In one embodiment, the pH value of the reaction solution during the shell-forming reaction is lower than the pH value of the reaction solution during the nucleation reaction.

[0046] In one embodiment, the flow rate of the Cu molten metal 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 be further selected as 10-15 L / h.

[0047] In this disclosure, the preferred flow rate of Cu molten metal is 10-15 L / h, which can increase growth and control the shell structure.

[0048] In one embodiment, when performing the shell-forming reaction in step (2), the stirring frequency of the reaction solution is 30-55Hz, for example, it can be 30Hz, 35Hz, 40Hz, 45Hz, 50Hz or 55Hz, etc.

[0049] In this disclosure, the stirring frequency of the reaction solution during the shell-forming reaction is 30-55Hz, 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, leading to secondary nucleation.

[0050] In one embodiment, the first increment in step (2) is the particle size D50 increment of 2-10 μm, for example, it can be 2 μm, 4 μm, 6 μm or 8 μm, etc.

[0051] In this disclosure, the first increment is that the particle size D50 increment is 2-10 μm, which helps the nucleation reaction of the copper-sodium cathode material precursor to obtain a core with a suitable particle size.

[0052] In one embodiment, step (2) the second increment: the particle size D50 increment is 1-5 μm, for example, it can be 1 μm, 3 μm or 5 μm, etc.

[0053] In this disclosure, the second increment is that the particle size D50 increment is 1-5 μm, which helps the shell formation reaction of the copper-sodium cathode material precursor to obtain a shell of suitable thickness.

[0054] As an optional technical solution of this disclosure, the preparation method of the base liquid includes:

[0055] Water and pH adjuster are added to the reactor and stirred to obtain a bottom solution with a pH value of 8-13.

[0056] In this disclosure, the purpose of preparing a base solution with a pH value of 8-13 is to allow for experiments to be conducted according to experimental requirements and to effectively control the reaction.

[0057] In one embodiment, the pH adjuster is an alkaline solution.

[0058] In one embodiment, the alkaline solution comprises ammonia.

[0059] In one embodiment, the concentration of the ammonia water is 0-6 g / L, for example, it can be 0, 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L or 6 g / L.

[0060] In one embodiment, the working temperature of the base liquid is 30-85°C, for example, it can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C or 85°C, and can be further selected as 40-85°C.

[0061] In this disclosure, the preferred working temperature of the base liquid is 40-85℃, and the working temperature of the base liquid can be adjusted according to actual needs.

[0062] In one embodiment, nitrogen gas is introduced during the stirring process.

[0063] In this disclosure, the purpose of introducing nitrogen gas during the stirring process is to prevent the material from being oxidized during the reaction.

[0064] In one embodiment, the stirring frequency during the stirring process is 30-60Hz, for example, it can be 30Hz, 40Hz, 50Hz or 60Hz.

[0065] In this disclosure, the preparation method of the base liquid uses a stirring frequency of 30-60Hz for stirring, which can make the base liquid disperse more evenly and fully. The stirring frequency can be adjusted according to actual needs.

[0066] As an optional technical solution of this disclosure, the preparation method includes the following steps:

[0067] (I) Prepare a liquid metal M with a concentration of 0.1-2.5 mol / L according to a certain molar ratio;

[0068] Prepare Cu metal liquid with a concentration of 0.1-1.1 mol / L according to a certain molar ratio;

[0069] (II) Preparation of the bottom liquid in the reactor: Add water to the reactor and heat the reactor to 30-85℃. Then add pH adjuster and purge with nitrogen gas for stirring. The stirring frequency is 30-60Hz to obtain a bottom liquid with a pH value of 8-13.

[0070] The pH adjuster includes an alkaline solution;

[0071] (III) Feed M metal solution, ammonia water and liquid alkali with a flow rate of 5 - 20 L / h into the reaction kettle containing the bottom liquid, and conduct 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 feeding the M metal solution, and continue to feed Cu metal solution with a flow rate of 2 - 15 L / h into the reaction kettle containing the bottom liquid, and conduct 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 feeding the Cu metal solution;

[0072] (IV) Repeat step (III) until the copper-containing sodium-ion battery positive electrode material precursor with a multi-level and hierarchical core-shell structure is synthesized.

[0073] 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.

[0074] In the third aspect, the present disclosure provides a copper-containing sodium-ion battery positive electrode material, which is prepared from the copper-containing sodium-ion battery positive electrode material precursor described in the first aspect;

[0075] The chemical structural formula of the copper-containing sodium-ion battery positive electrode material is Na x M y Cu n O2, where 0.5 ≤ x ≤ 1, 0 < y < 1, 0 < n < 1, and y + n = 1.

[0076] The copper-containing sodium-ion battery positive electrode material prepared in the present disclosure has excellent electrochemical performance.

[0077] 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. [[ID=**26**]]

[0078] In the present disclosure, 0 < y < 1, for example, it can be 0.2, 0.4, 0.6 or 0.8, etc.

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

[0080] 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 positive electrode material described in the third aspect.

[0081] The numerical range described in this 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 brevity, this disclosure will not exhaustively list the specific point values ​​included in the range.

[0082] Compared with the prior art, this disclosure has the following beneficial effects:

[0083] (1) This disclosure designs a core-shell structured copper-sodium cathode material precursor, wherein the core-shell structure includes a core and a multi-layered shell covering the surface of the core, and the multi-layered shell consists of Cu(OH)2 layers and M layers alternately stacked sequentially along a direction away from the core. y The outermost layer of the multilayer shell is a Cu(OH)2 layer. This structure allows Cu to be uniformly distributed within the precursor bulk phase, reducing diffusion inhomogeneity and resulting in superior performance of the prepared copper-sodium cathode material.

[0084] (2) The preparation method provided in this disclosure effectively avoids the problems of uneven distribution of many metal elements in the precursor, difficulty in uniform precipitation and easy segregation. The preparation method can effectively control the physicochemical data such as morphology, particle size, primary particles, secondary particles, elemental composition, specific surface area, tapping, moisture, sphericity and compactness of the precursor. At the same time, it can also effectively control the size and thickness of the core and shell to obtain high-performance precursor materials.

[0085] (3) The preparation method provided in this 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 the relevant problems in industrialization.

[0086] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0087] The accompanying drawings are used to provide a further understanding of the technical solutions in this paper and form part of the specification. They are used together with the embodiments of this application to explain the technical solutions in this paper and do not constitute a limitation on the technical solutions in this paper.

[0088] Figure 1 This is a cross-sectional view of a copper-sodium cathode material precursor prepared in a specific embodiment of this disclosure.

[0089] Figure 2 This is a SEM image of the copper-sodium cathode material precursor prepared in Example 1 of this disclosure.

[0090] Figure 3 This is a TEM image of the copper-sodium cathode material precursor prepared in Example 1 of this disclosure.

[0091] Figure 4 SEM image of the copper-containing sodium-ion battery cathode material precursor prepared in Comparative Example 1 in the present disclosure. Specific embodiments

[0092] The technical solutions of the present disclosure will be further described below through specific embodiments. 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 to the present disclosure.

[0093] Example 1

[0094] 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;

[0095] The inner 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;

[0096] The multiple outer shells are successively and alternately stacked Cu(OH)2 layers and M y (OH)2 layers along the direction away from the inner 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;

[0097] The particle size D50 of the copper-containing sodium-ion battery cathode material precursor is 10 μm.

[0098] 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:

[0099] (1) Prepare an M metal solution with a concentration of 1.7 mol / L according to a certain molar ratio;

[0100] Prepare a Cu metal solution with a concentration of 1.0 mol / L according to a certain molar ratio;

[0101] 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;

[0102] (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;

[0103] Among them, the pH regulator is ammonia water, and the concentration of ammonia water is 4 g / L;

[0104] (3) Introduce M metal solution with a flow rate of 15 L / h into the reactor containing the bottom liquid, and at the same time raise the pH value of the reaction solution to 10.3. Conduct a nucleation reaction under the stirring condition with a stirring frequency of 55 Hz. When the first increment of the particle size D50 is 3 μm, stop introducing the M metal solution, and continue to introduce Cu metal solution with a flow rate of 10 L / h into the reactor containing the bottom liquid. Lower the pH value to 10.2, and conduct a shell-forming reaction under the stirring condition with a stirring frequency of 40 Hz. When the second increment of the particle size D50 is 2 μm, stop introducing the Cu metal solution;

[0105] (4) Repeat step (3) until the copper-containing sodium-ion battery cathode material precursor is synthesized.

[0106] Figure 2 The SEM image of the copper-containing sodium-ion battery cathode material precursor prepared in this embodiment is shown. As can be seen from the figure, the sphericity of this material is relatively good and the particle size is controllable.

[0107] Figure 3 The TEM image of the copper-containing sodium-ion battery cathode material precursor prepared in this embodiment is shown. As can be seen from the figure, this material has a core-shell structure, and this structure can make Cu evenly distributed in the precursor matrix, reducing the phenomenon of uneven diffusion.

[0108] Example 2

[0109] 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;

[0110] 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;

[0111] 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;

[0112] The particle size D50 of the copper-containing sodium-ion battery cathode material precursor is 10 μm.

[0113] 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:

[0114] (1) Prepare an M metal solution with a concentration of 2.1 mol / L according to a certain molar ratio;

[0115] Prepare a Cu metal solution with a concentration of 1.0 mol / L according to a certain molar ratio;

[0116] 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;

[0117] (2) Prepare the bottom liquid of the reaction kettle: Add water with a volume of 1 / 3 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;

[0118] Among them, the pH regulator is ammonia water, and the concentration of ammonia water is 6 g / L;

[0119] (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. Perform 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 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;

[0120] (4) Repeat step (3) until the copper-containing sodium battery cathode material precursor is synthesized.

[0121] Example 3

[0122] The present disclosure provides a copper-containing sodium battery cathode material precursor. The copper-containing sodium 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;

[0123] 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;

[0124] The multiple outer shells are successively and alternately stacked along the direction away from the core, with a Cu(OH)2 layer and a M y (OH)2 layer. 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;

[0125] The particle size D50 of the copper-containing sodium battery cathode material precursor is 15 μm.

[0126] This embodiment also provides a method for preparing the above-mentioned copper-containing sodium-ion battery cathode material precursor, and the preparation method includes the following steps:

[0127] (1) Prepare an M metal solution with a concentration of 1.8 mol / L according to a certain molar ratio;

[0128] Prepare a Cu metal solution with a concentration of 0.9 mol / L according to a certain molar ratio;

[0129] 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, and the Cu metal solution is a copper sulfate solution;

[0130] (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, with a stirring frequency of 60 Hz, to obtain a bottom liquid with a pH value of 10.1;

[0131] Among them, the pH regulator is ammonia water, and the concentration of ammonia water is 3 g / L;

[0132] (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, and carry out a nucleation reaction under the stirring condition of 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 a shell-forming reaction under the stirring condition of a stirring frequency of 45 Hz. When the second increment of the particle size D50 is 2 μm, stop introducing the Cu metal solution;

[0133] (4) Repeat step (3) until the copper-containing sodium-ion battery cathode material precursor is synthesized.

[0134] Example 4

[0135] The present disclosure provides a copper-containing sodium-ion battery cathode material precursor, the copper-containing sodium-ion battery cathode material precursor is a core-shell structure, and the core-shell structure includes a core and multiple outer shells coated on the surface of the core;

[0136] 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;

[0137] The multiple outer shells are Cu(OH)2 layers and M alternately stacked in sequence along the direction away from the core yThe outermost layer of the multi-layer shell is a Cu(OH)2 layer, and the multi-layer shell has 3 layers.

[0138] The particle size D50 of the copper-containing sodium cathode material precursor is 15 μm.

[0139] This embodiment also provides a method for preparing the above-mentioned copper-sodium cathode material precursor, the preparation method comprising the following steps:

[0140] (1) Prepare a metal M solution with a concentration of 2.0 mol / L according to a certain molar ratio;

[0141] Prepare a Cu metal liquid with a concentration of 1.0 mol / L according to a certain molar ratio;

[0142] The M metal liquid comprises nickel sulfate, manganese sulfate, ferrous sulfate, and zinc sulfate, wherein 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, and the Cu metal liquid is a copper sulfate solution.

[0143] (2) Preparation of the bottom liquid of the reactor: Add water to the reactor with a volume of 1 / 3, heat the reactor to 70°C, add pH adjuster, and stir with nitrogen gas at a stirring frequency of 60Hz to obtain a bottom liquid with a pH value of 9.8.

[0144] The pH adjuster is ammonia water, and the concentration of ammonia water is 2g / L;

[0145] (3) M metal liquid with a flow rate of 16 L / h is introduced into the reactor containing the bottom liquid, and the pH value of the reaction liquid is raised to 9.8. Nucleation reaction is carried out under the stirring condition of 57 Hz. When the first increment of particle size D50 is 3 μm, the introduction of M metal liquid is stopped, and Cu metal liquid with a flow rate of 10 L / h is continued to be introduced into the reactor containing the bottom liquid to lower the pH value to 9.7. Shell formation reaction is carried out under the stirring condition of 47 Hz. When the second increment of particle size D50 is 2 μm, the introduction of Cu metal liquid is stopped.

[0146] (4) Repeat step (3) until the copper-containing sodium cathode material precursor is synthesized.

[0147] Example 5

[0148] This disclosure provides a copper-sodium-containing cathode material precursor, wherein the copper-sodium-containing cathode material precursor has a core-shell structure, and the core-shell structure includes a core and a multi-layered shell covering the surface of the core.

[0149] The kernel is M. y(OH)2, where 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;

[0150] The multi-layer shell is a Cu(OH)2 layer and an M(OH)2 layer alternately stacked in sequence along the direction away from the core. 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; 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;

[0151] The particle size D50 of the copper-containing sodium-ion battery cathode material precursor is 18 μm.

[0152] 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:

[0153] (1) Prepare an M metal solution with a concentration of 2.0 mol / L according to a certain molar ratio;

[0154] Prepare a Cu metal solution with a concentration of 1.0 mol / L according to a certain molar ratio;

[0155] Among them, the M metal solution includes manganese sulfate, nickel 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. The Cu metal solution is a copper sulfate solution;

[0156] (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 65 °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 9.7;

[0157] Among them, the pH regulator is ammonia water with a concentration of 4 g / L;

[0158] (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 9.7. Carry out a nucleation reaction under the stirring condition with a stirring frequency of 60 Hz. When the first increment of the particle size D50 is 4 μm, stop introducing the M metal solution, and continue to introduce the Cu metal solution with a flow rate of 12 L / h into the reaction kettle containing the bottom liquid. Lower the pH value to 9.5, and carry out a shell-forming reaction under the stirring condition with a stirring frequency of 50 Hz. When the second increment of the particle size D50 is 2 μm, stop introducing the Cu metal solution;

[0159] (4) Repeat step (3) until the copper-containing sodium-ion battery cathode material precursor is synthesized.

[0160] Example 6

[0161] The difference between this embodiment and Embodiment 1 is that the concentration of the M metal liquid is 0.05 mol / L.

[0162] The remaining preparation methods and parameters are consistent with those in Example 1.

[0163] Example 7

[0164] The difference between this embodiment and Embodiment 1 is that the concentration of the M metal liquid is 3 mol / L.

[0165] The remaining preparation methods and parameters are consistent with those in Example 1.

[0166] Example 8

[0167] The difference between this embodiment and Embodiment 1 is that the concentration of Cu metal liquid is 0.05 mol / L.

[0168] The remaining preparation methods and parameters are consistent with those in Example 1.

[0169] Example 9

[0170] The difference between this embodiment and embodiment 1 is that, during the process of introducing the M metal liquid in step (3), 0.5 g / L of ammonia water is also introduced.

[0171] The remaining preparation methods and parameters are consistent with those in Example 1.

[0172] Comparative Example 1

[0173] This comparative example provides a method for preparing a copper-containing sodium-ion cathode material precursor, the method comprising the following steps:

[0174] (1) Weigh out the corresponding nickel sulfate, manganese sulfate, ferrous sulfate and copper sulfate raw materials according to the molar ratio of Ni:Mn:Fe:Cu of 0.2:0.5:0.15:0.15 to prepare a metal liquid with a concentration of 2.0 mol / L;

[0175] (2) Preparation of the bottom liquid of the reactor: Add water to the reactor with a volume of 1 / 3, heat the reactor to 70°C, add pH adjuster, and stir with nitrogen gas at a stirring frequency of 55Hz to obtain a bottom liquid with a pH value of 10.5.

[0176] The pH adjuster is ammonia water, and the concentration of ammonia water is 4g / L;

[0177] (3) A metal liquid with a flow rate of 15 L / h is introduced into a reaction vessel containing the bottom liquid, and the pH value of the metal liquid is raised to 10.5. Nucleation reaction is carried out under stirring conditions with a stirring frequency of 55 Hz. When the particle size D50 increment is 5 μm, the pH value is reduced to 10.3 and the flow rate is reduced to 10 L / h. Shell formation reaction is carried out under stirring conditions with a stirring frequency of 45 Hz until the copper-sodium cathode material precursor is obtained.

[0178] Figure 4 The SEM image of the copper-sodium cathode material precursor prepared in this comparative example is shown. As can be seen from the figure, the morphology is poor, the sphericity is poor, the particle size is inconsistent, and there is a serious segregation phenomenon.

[0179] Performance testing

[0180] The copper-containing sodium-ion battery precursors prepared in the above examples and comparative examples are used to make copper-containing sodium-ion battery materials, and then to make positive electrode sheets. These materials are then assembled with negative electrode sheets, separators, and electrolytes to obtain sodium-ion batteries.

[0181] The preparation method of copper-sodium-containing cathode material includes: mixing the precursor materials obtained in each embodiment and comparative example with a sodium source, performing a mixing treatment, wherein the mass ratio of Na:Me (metal element in the precursor material) is 1.05:1, and then performing high-temperature sintering treatment, with a sintering temperature of 950℃ and a sintering time of 12h, to obtain copper-sodium-containing cathode material.

[0182] The preparation method of the positive electrode sheet includes: weighing and mixing the above-mentioned 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 mixture is then made into a slurry, coated onto aluminum foil, vacuum dried, and after drying, cut and punched into positive electrode sheets with a diameter of 12 mm.

[0183] The preparation method of 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, using glass fiber as the separator, and assembling the battery into a button cell in an argon glove box.

[0184] The electrochemical performance of the sodium-ion battery was tested under the following conditions: charge-discharge test was conducted at a voltage range of 1.5-4.0V and a charge-discharge rate of 0.1C. The initial charge-discharge specific capacity and initial coulombic efficiency were obtained, and the test results are shown in Table 1.

[0185] Table 1

[0186]

[0187]

[0188] analyze:

[0189] As shown in the table above, this disclosure designs a multi-level, hierarchical core-shell structure for a copper-sodium cathode material precursor. This structure allows Cu to be uniformly distributed within the bulk phase of the precursor, reducing diffusion inhomogeneity and resulting in superior performance of the prepared copper-sodium cathode material.

[0190] As can be seen from Examples 1 and Examples 6-8, if the concentration of the M metal liquid or the Cu metal liquid is too low, the supersaturation will be too low, which will lead to a slow reaction rate and increase the growth time; if the concentration of the M metal liquid is too high, the supersaturation will be too high, which will lead to faster growth and make it difficult to control the particle size.

[0191] As can be seen from Examples 1 and 9, if ammonia water is also introduced during the process of introducing the M metal liquid, the reaction rate of metal ions can be slowed down, resulting in high compactness and good sphericity of the M layer.

[0192] As can be seen from Example 1 and Comparative Example 1, if Ni, Mn, Fe and Cu metal liquids are all mixed together and fed into the liquid together, the materials will not settle uniformly and there will be a certain degree of segregation, resulting in poor sphericity and morphology of the materials, which will have a certain impact on electrical properties.

[0193] The applicant declares that this disclosure illustrates the process method of this disclosure through the above embodiments, but this disclosure is not limited to the above process steps, that is, it does not mean that this disclosure must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to this disclosure, equivalent substitutions of the raw materials selected in this disclosure, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this disclosure. For example, the core of the copper-sodium cathode material precursor can also be Cu(OH)2, and the multilayer shell is M, which is alternately stacked along a direction away from the core. y The outermost layer of the multi-layered shell is M (OH)2 layer and Cu(OH)2 layer. y (OH)2 layer.

Claims

1. A copper-containing sodium battery positive electrode material precursor, the copper-containing sodium battery positive electrode material precursor being a core-shell structure, the core-shell structure comprising an inner core and a multilayer shell covering the surface of the inner core. The inner core is , 0 < y < 1, M is a metal element other than copper; The multilayer shell is sequentially and alternately arranged in the direction away from the core by Cu(OH)2 layers and The outermost layer of the multilayer shell is a Cu(OH)2 layer.

2. The copper-containing sodium electro-positive cathode material precursor of claim 1, wherein, The M comprises 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 electro-positive cathode material precursor of claim 1, wherein, The particle size of the copper-containing sodium battery positive electrode material precursor is 10 μm≤D50≤20 μm.

4. The copper-containing sodium electro-positive cathode material precursor of claim 1, wherein, The number of layers of the multilayer shell is at least 3.

5. The copper-containing sodium electro-positive cathode material precursor of claim 4, wherein, The number of layers of the multilayer shell is 3-10.

6. A method of preparing a copper-containing sodium electro-positive electrode material precursor according to any one of claims 1 to 5, characterized in that, The preparation method comprises the following steps: (1) M metal liquid and Cu metal liquid are respectively prepared; (2) the M metal liquid is introduced into a reactor containing a base solution to perform nucleation reaction, when the particle size D50 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 base solution to perform shell formation reaction, when the particle size D50 reaches a second increment, the introduction of the Cu metal liquid is stopped; (3) step (2) is repeated until the copper-containing sodium battery positive electrode material precursor with a core-shell structure is synthesized.

7. The production method according to claim 6, characterized by, The concentration of the M metal liquid is 0.1-2.5 mol / L.

8. The preparation method according to claim 7, characterized in that, The concentration of the M metal liquid is 1.7-2 mol / L.

9. The preparation method according to claim 6, characterized in that, The concentration of the Cu metal liquid is 0.1-1.1 mol / L.

10. The method of claim 6, wherein, During the introduction of the M metal liquid in step (2), ammonia and liquid alkali are also introduced.

11. The preparation method according to claim 6, characterized in that, When the nucleation reaction in step (2) is performed, the pH value of the reaction solution is 8-13.

12. The method of claim 6, wherein, The flow rate of the introduction of the M metal liquid in step (2) is 5-20 L / h.

13. The preparation method according to claim 6, characterized in that, When the nucleation reaction in step (2) is performed, the stirring frequency of the reaction solution is 30-60 Hz.

14. The method of claim 6, wherein, During the introduction of the Cu metal liquid in step (2), ammonia and liquid alkali are also introduced.

15. The preparation method according to claim 6, characterized in that, When the shell formation reaction in step (2) is performed, the pH value of the reaction solution is 9-12.

16. The method of claim 6, wherein, The flow rate of the introduction of the Cu metal liquid in step (2) is 2-15 L / h.

17. The method of claim 6, wherein, When the shell formation reaction in step (2) is performed, the stirring frequency of the reaction solution is 30-55 Hz.

18. The method of claim 6, wherein, The first increment in step (2): the particle size D50 increment is 2-10 μm.

19. The method of claim 6, wherein, The second increment in step (2): the particle size D50 increment is 1-5 μm.

20. The method of claim 6, wherein, The preparation method of the base solution comprises: water and a pH regulator are added to a reactor, and stirring treatment is performed to obtain a base solution with a pH value of 8-13.

21. The method of claim 6, wherein, The working temperature of the base solution is 30-85℃.

22. The preparation method according to claim 20, characterized in that, Nitrogen is introduced during the stirring treatment.

23. The preparation method according to claim 20, characterized in that, The stirring frequency during the stirring treatment is 30-60 Hz.

24. The method of claim 6, wherein, The preparation method comprises the following steps: (I) M metal liquid with a concentration of 0.1-2.5 mol / L is prepared according to a certain molar ratio; Cu metal liquid with a concentration of 0.1-1.1 mol / L is prepared according to a certain molar ratio; (II) base solution of the reactor is prepared: water is added to the reactor, and the temperature of the reactor is heated to 30-85℃, then a pH regulator is added, and nitrogen is introduced for stirring treatment, the stirring frequency is 30-60 Hz, and a base solution with a pH value of 8-13 is obtained; The pH regulator comprises lye; (III) introducing M metal liquid, ammonia and liquid alkali into the reactor containing the base solution at a flow rate of 5-20 L / h, and performing nucleation reaction under stirring at 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 introducing Cu metal liquid into the reactor containing the base solution at a flow rate of 2-15 L / h, and performing shell formation reaction under stirring at 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) repeating step (III) until the copper-containing sodium battery positive electrode material precursor with multi-layer hierarchical core-shell structure is synthesized.

25. A sodium battery cathode material containing copper prepared from the precursor of the sodium battery cathode material containing copper according to any one of claims 1-5, characterized in that, The chemical structural formula of the copper-containing sodium electric positive electrode material is wherein 0.5≤x≤1, 0 y<1, 0 n<1, y+n=1.

26. A sodium ion battery comprising the copper-containing sodium battery positive electrode material according to claim 25.

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