Sodium-ion battery positive electrode material, preparation method therefor and sodium-ion battery

Abstract

A sodium-ion battery positive electrode material, a preparation method therefor, and a sodium-ion battery. The sodium-ion battery positive electrode material comprises a sodium-based nickel-iron-manganese-zinc quaternary metal oxide. The crystalline phase of the sodium-ion battery positive electrode material comprises a zinc oxide phase with the mass percentage content of less than or equal to 1.5 wt%, and the particle size distribution of the sodium-ion battery positive electrode material meets: (Dv90-Dv10) / Dv50<1.35, wherein Dv10, Dv50 and Dv90 respectively represent the particle sizes corresponding to the particle cumulative volume distribution percentages of 10%, 50% and 90% for the sodium-ion battery positive electrode material, and the units of Dv10, Dv50 and Dv90 are all μm.

Description

Sodium-ion battery positive electrode material, preparation method thereof and sodium-ion battery

[0001] The present disclosure claims priority to the Chinese patent application No. 202410454113.2, filed on April 15, 2024, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of sodium-ion batteries, and in particular to a sodium-ion battery positive electrode material, a preparation method thereof and a sodium-ion battery. BACKGROUND

[0003] A sodium-ion battery is a kind of secondary battery, which mainly relies on the movement of sodium ions between the positive electrode and the negative electrode to work, and has the advantages of abundant reserves and low price.

[0004] The positive electrode material of a sodium-ion battery is usually a nickel-iron-manganese ternary material or a nickel-zinc-iron-manganese quaternary material. The common preparation method of the nickel-zinc-iron-manganese quaternary material usually includes a solid phase method and a quaternary hydroxide precursor sintering method. SUMMARY

[0005] In view of this, the present disclosure provides a sodium-ion battery positive electrode material and a novel preparation method thereof. The sodium-ion battery positive electrode material is a quaternary sodium oxide positive electrode material with low particle size dispersion and low impurity phase content.

[0006] In a first aspect, some embodiments of the present disclosure provide a sodium-ion battery positive electrode material, which includes a sodium-based nickel-iron-manganese-zinc quaternary metal oxide. The crystal phase of the sodium-ion battery positive electrode material includes a zinc oxide phase with a mass percentage of less than or equal to 1.5wt%. The particle size distribution of the sodium-ion battery positive electrode material satisfies: (D v 90-D v 10) / D v 50<1.35;

[0007] wherein, D v 10, D v 50, D v 90 respectively represent the particle size corresponding to the cumulative volume distribution percentage of 10%, 50%, and 90% of the sodium-ion battery positive electrode material, and the units of D v 10, D v 50, D v 90 are μm.

[0008] Compared with the common sodium-based nickel-iron-manganese-zinc quaternary metal oxide, the particle size distribution of the above-mentioned sodium-ion battery positive electrode material provided by the present disclosure is narrow, and the impurity phase content is low, which is convenient for guaranteeing good electrochemical performance.

[0009] In a second aspect, some embodiments of the present disclosure provide a preparation method of a sodium-based positive electrode material, comprising: mixing a nickel-iron-manganese ternary hydroxide precursor with a zinc source and a sodium source to obtain a mixture; and sintering the mixture to obtain a sodium-based nickel-iron-manganese-zinc quaternary metal oxide.

[0010] The preparation method of the nickel-iron-manganese-zinc quaternary sodium-based positive electrode material provided by some embodiments of the present disclosure effectively ensures that the elements in the prepared sodium-based quaternary oxide positive electrode material are uniformly distributed, the phase purity of the positive electrode material is high, the morphology or size consistency is high, and the like, so as to ensure that the positive electrode material has excellent electrochemical performance.

[0011] In a third aspect, some embodiments of the present disclosure provide a sodium ion battery, which comprises the sodium-based positive electrode material according to the first aspect of the present disclosure or the sodium-based positive electrode material prepared by the preparation method according to the second aspect of the present disclosure. The sodium ion battery has excellent electrochemical performance due to the use of the above-mentioned sodium-based positive electrode material, which is beneficial to its wide application. BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 is a scanning electron microscope (SEM) photo of a sodium-based quaternary oxide positive electrode material prepared according to Embodiment 1 of the present disclosure;

[0013] FIG. 2 is a SEM photo of a sodium-based quaternary oxide positive electrode material prepared according to Embodiment 2 of the present disclosure;

[0014] FIG. 3 is a SEM photo of a sodium-based quaternary oxide positive electrode material prepared according to Embodiment 3 of the present disclosure;

[0015] FIG. 4 is a SEM photo of a sodium-based quaternary oxide positive electrode material prepared according to Embodiment 4 of the present disclosure;

[0016] FIG. 5 is a SEM photo of a sodium-based quaternary oxide positive electrode material prepared according to Comparative Example 1;

[0017] FIG. 6 is a SEM photo of a sodium-based quaternary oxide positive electrode material prepared according to Comparative Example 2;

[0018] FIG. 7 is an XRD spectrum of the positive electrode material according to Embodiment 1;

[0019] FIG. 8 is a flowchart of a preparation method of a sodium-based positive electrode material according to some embodiments of the present disclosure; and

[0020] FIG. 9 is a block diagram of a sodium ion battery according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0021] Embodiments of the present disclosure are described below in detail with reference to examples shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary only, and are for the purpose of explanation of the present disclosure, and cannot be understood as a limitation of the present disclosure.

[0022] The technical solutions of some embodiments of the present disclosure will be described below in detail with reference to the drawings.

[0023] The preparation method of the nickel-zinc-iron-manganese quaternary positive electrode material generally includes a solid phase method and a quaternary hydroxide precursor sintering method.

[0024] The solid phase method generally mixes a nickel source, a zinc source, an iron source, a manganese source, and a sodium source, and then performs high-temperature sintering. In the solid phase method, the types of raw materials are many, and it is difficult to fully mix and uniformly mix the multiple raw materials, thereby causing the particle size distribution of the obtained quaternary positive electrode material to be greatly different, the morphology consistency to be low and abnormal morphology to exist, and the impurity content to be high, affecting the electrochemical performance of the positive electrode material, etc.

[0025] The quaternary hydroxide precursor sintering method is to mix a nickel-zinc-iron-manganese quaternary hydroxide precursor with a sodium source, and then perform sintering. In the preparation of the quaternary hydroxide precursor, due to the large difference in the precipitation coefficient Ksp of zinc ions and other metal ions, the nickel, cobalt, and manganese element segregation phenomenon exists in the co-precipitation product-quaternary hydroxide precursor, the elements are not uniformly distributed, the quaternary hydroxide has abnormal morphology, the morphology consistency is poor, and further causes the particle consistency of the quaternary positive electrode material formed by sintering the quaternary hydroxide with the sodium source to be low, and the morphology distribution to have great difference.

[0026] In view of this, some embodiments of the present disclosure provide a nickel-zinc-iron-manganese quaternary sodium battery positive electrode material with narrow particle size distribution and low impurity content, and a preparation method thereof.

[0027] Some embodiments of the present disclosure provide a preparation method of a sodium battery positive electrode material, as shown in FIG. 8, which includes the following steps (1) and (2).

[0028] In step (1), a nickel-iron-manganese ternary hydroxide precursor is mixed with a zinc source and a sodium source to obtain a mixture.

[0029] In step (2), the mixture is sintered to obtain a sodium-based nickel-iron-manganese-zinc quaternary metal oxide.

[0030] The preparation method of the sodium-based nickel-iron-manganese-zinc quaternary positive electrode material provided by some embodiments of the present disclosure does not add nickel, cobalt, manganese and zinc elements in the form of one raw material, but sintering after mixing the nickel-iron-manganese ternary hydroxide formed by co-precipitation of nickel, cobalt and manganese elements with similar precipitation coefficients and the zinc element raw material with a large difference in precipitation coefficient from the above three metal elements and a sodium source, which effectively ensures that each element in the prepared quaternary oxide positive electrode material is uniformly distributed, the phase purity of the positive electrode material is high, the morphology or size consistency is high, and further ensures that the prepared positive electrode material has excellent electrochemical performance, avoiding the problem of poor morphology or size consistency and high content of impurities in the sodium-based quaternary oxide positive electrode material caused by directly using the nickel-zinc-iron-manganese quaternary hydroxide obtained by uneven co-precipitation of nickel, iron, manganese and zinc as a raw material.

[0031] In addition, compared with the preparation of the quaternary sodium battery positive electrode material by using a nickel source, a zinc source, an iron source, a manganese source and a sodium source through a solid phase method, the above preparation method provided by some embodiments of the present disclosure reduces the types of raw materials, and correspondingly reduces the impurities that may be mixed in each raw material, which is beneficial to the full mixing of each raw material, thereby facilitating the uniform growth of nickel, cobalt, manganese and zinc with the sodium source during sintering, and avoiding the problems of large particle size distribution difference, low morphology consistency and high impurity content of the obtained positive electrode material.

[0032] Therefore, the preparation method of the quaternary sodium battery positive electrode material provided by some embodiments of the present disclosure can prepare a quaternary positive electrode material with high particle consistency, uniform particle size distribution, high phase purity and good electrochemical performance. Moreover, the above preparation method is simple in process and strong in operability, and is suitable for large-scale production.

[0033] In some embodiments of the present disclosure, in step (1), the sodium source can include one or more of sodium hydroxide (NaOH), sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), etc., but is not limited thereto. The zinc source can include one or more of zinc carbonate (ZnCO3), zinc oxide (ZnO) and zinc hydroxide (Zn(OH)2), etc., but is not limited thereto. In some embodiments, the zinc source is one or both of ZnCO3 and ZnO.

[0034] In some embodiments of the present disclosure, in step (1), the chemical formula of the nickel-iron-manganese ternary hydroxide precursor can be represented as Ni x Fe y Mn z (OH)2. Wherein, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1. The values of x, y and z in the nickel-iron-manganese ternary hydroxide precursor can be controlled according to the molar ratio of the three elements of nickel, iron and manganese in the sodium battery positive electrode material—sodium-based nickel-iron-manganese-zinc quaternary metal oxide to be prepared.

[0035] In some embodiments, 0.1≤x<1, 0.1≤y<1, 0.1≤z<1. For example, x, y, z can be independently 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.60, 0.70, 0.80, etc.

[0036] In some embodiments of the present disclosure, the chemical formula of the sodium-based nickel-iron-manganese-zinc quaternary metal oxide can be expressed as Na w Ni a Zn b Fe c Mn d O2, wherein 0<a<1, 0<b<1, 0<c<1, a+b+c+d=1; 0.67≤w≤1.2. In some embodiments, 0.1≤a≤0.5, 0.1≤b≤0.5, 0.1≤c≤0.5, 0.1≤d≤0.5.

[0037] In some embodiments of the present disclosure, when preparing the mixture in step (1), the nickel-iron-manganese ternary hydroxide precursor, zinc source and sodium source can be weighed according to the molar ratio of nickel, cobalt and manganese elements in the sodium-based quaternary metal oxide to be prepared to zinc and sodium elements.

[0038] It can be understood that the molar ratio of nickel, iron and manganese elements in the nickel-iron-manganese ternary hydroxide precursor is usually equal to the molar ratio of nickel, iron and manganese elements in the sodium-based quaternary metal oxide. For example, the aforementioned x:y:z=a:b:c.

[0039] In addition, considering that sodium elements are prone to loss during subsequent sintering, the sodium source can be within 10 mol% excess. In other words, the molar amount of sodium elements in the sodium source is 100%-110% of the sum of the molar amounts of nickel, iron and manganese elements in the nickel-iron-manganese ternary hydroxide precursor and the molar amount of zinc elements in the zinc source.

[0040] In some embodiments of the present disclosure, the nickel-iron-manganese ternary hydroxide precursor can be prepared by a coprecipitation method. In some embodiments, the preparation method of the nickel-iron-manganese ternary hydroxide precursor can include the following steps 1) to step 4).

[0041] In step 1), a nickel-iron-manganese metal salt solution is prepared according to the molar ratio of Ni, Fe and Mn as x:y:z.

[0042] In step 2), water is added to the reaction kettle, the stirring speed is set to 200 r / min-800 r / min, the temperature is raised to 40℃-80℃, and nitrogen gas is continuously introduced as a protective gas.

[0043] In step 3), a complexing agent and a precipitant are added to the reactor in step 2), and the pH in the reactor is adjusted to 10-13.

[0044] In step 4), the nickel-iron-manganese metal salt solution configured in step 1) is added to the reactor in step 3) with a complexing agent and a precipitant for a co-precipitation reaction. After the nickel-iron-manganese metal salt is consumed, the reaction material is collected, and solid-liquid separation is performed on the reaction material to obtain a solid product. The solid product is washed and dried to obtain a nickel-iron-manganese ternary hydroxide precursor.

[0045] For example, in steps 3) and 4), the complexing agent and the precipitant are added in the form of a solution.

[0046] In some embodiments, the precipitant can be a strong alkali solution, such as a sodium hydroxide solution or a potassium hydroxide solution. The complexing agent can be an ammonia solution. The concentration of the ammonia solution can be 0.1 mol / L-0.8 mol / L.

[0047] In step 4), the solid-liquid separation can be centrifugation or filtration.

[0048] It should be noted that during the above co-precipitation reaction process, the stirring speed, system temperature, and system pH can be maintained unchanged, or at least one of the stirring speed, system temperature, and system pH can be changed. For example, the co-precipitation reaction conditions are changed in stages to prepare nickel-iron-manganese ternary hydroxide precursors with different particle sizes as needed.

[0049] In the above step (2), the sintering can be performed in any sintering equipment with heating and ventilation functions. In some embodiments, the sintering is performed in a tube furnace.

[0050] In addition, the sintering can be performed under the condition of passing a certain atmosphere. For example, the sintering atmosphere can be an oxygen-containing atmosphere, such as at least one of oxygen or air. The oxygen-containing atmosphere is more conducive to the decomposition of the above nickel-iron-manganese ternary hydroxide precursor into an oxide to be combined with a sodium source to grow crystals.

[0051] For example, the sintering atmosphere can be compressed air, or oxygen, or a mixture of compressed air and oxygen. The gas flow of the sintering atmosphere can be in the range of 0.1 L / min-10 L / min.

[0052] In some embodiments of the present disclosure, in step (2), the sintering temperature can be in the range of 500°C-1200°C, and the sintering time is 5h-20h. The sintering temperature refers to the holding temperature during sintering, and the sintering time refers to the holding time at the aforementioned holding temperature.

[0053] It can be understood that the suitable sintering temperature can ensure the sufficient fusion between the ternary nickel-iron-manganese hydroxide precursor, the zinc source and the sodium source, and ensure the growth of the sodium-based nickel-zinc-iron-manganese quaternary oxide crystal grains, and also can avoid the excessive growth of the sodium-based quaternary oxide crystals which seriously affects the specific capacity and kinetic performance of the material. The suitable holding time can ensure the sufficient growth of the sodium-based quaternary oxide and the suitable grain size.

[0054] For example, the sintering temperature can be 600℃, 650℃, 700℃, 800℃, 850℃, 900℃, 950℃, 980℃, 1000℃, 1000℃, 1100℃, etc. The sintering time is, for example, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, etc.

[0055] In some embodiments, the sintering temperature is 800℃-1100℃, and the sintering time is 10h-18h. Under this process, sintering is more conducive to obtaining the positive electrode material with high consistency in particle morphology and uniform size distribution.

[0056] In some embodiments, the temperature rising rate from room temperature to the above-mentioned sintering temperature can be 1℃ / min-10℃ / min, for example, the temperature rising rate is 2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, 8℃ / min or 9℃ / min, etc. In some embodiments, the temperature rising rate can be 3℃ / min-6℃ / min.

[0057] In some embodiments of the present disclosure, after the sintering in the above-mentioned step (2), the preparation method of the sodium battery positive electrode material can further include: crushing, screening and demagnetizing the sintered product to obtain a layered sodium-based quaternary metal oxide positive electrode material with suitable particle size and low impurity content.

[0058] In some embodiments, a screen is used for screening; the mesh number of the screen used can be 50-300, for example, the mesh number of the screen is 80, 100, 120, 150, 200, 230, 270, etc.

[0059] In some embodiments of the present disclosure, after the sintering, the preparation method further includes surface coating the obtained sodium-based nickel-iron-manganese-zinc quaternary metal oxide to form a coating layer. For example, the coating layer material can include one or more of oxides (such as aluminum oxide), fluorides (such as sodium fluoride and aluminum fluoride), and phosphates (such as NaV2(PO4)2F3).

[0060] Some embodiments of the present disclosure also provide a sodium battery positive electrode material, which includes a sodium-based nickel-iron-manganese-zinc quaternary metal oxide.

[0061] The crystal phase of the sodium battery cathode material includes a zinc oxide phase with a mass percentage of less than or equal to 1.5 wt%, and the particle size distribution of the sodium battery cathode material satisfies: (D v 90-D v 10) / D v 50<1.35; wherein, D v 10, D v 50, D v 90 respectively represent the particle sizes corresponding to the particle cumulative volume distribution percentages of 10%, 50%, and 90% of the sodium battery cathode material, and D v 10, D v 50, D v 90 are all in units of μm.

[0062] Some embodiments of the present disclosure provide the sodium battery cathode material with high particle morphology consistency, uniform particle size distribution, very low proportion of non-capacity-contribution phases, and high purity of capacity-contribution phases, thereby having good electrochemical performance, such as high coulombic efficiency and good cycle performance and rate performance. The sodium battery cathode material is prepared by using the above preparation method provided in some embodiments of the present disclosure.

[0063] In some embodiments of the present disclosure, the chemical formula of the sodium-based nickel-iron-manganese-zinc quaternary metal oxide includes Na x Ni a Zn b Fe c Mn d O2, wherein 0 < a < 1, 0 < b < 1, 0 < c < 1, and a + b + c + d = 1; 0.67 ≤ w ≤ 1.2. In some embodiments, 0.1 ≤ a ≤ 0.5, 0.1 ≤ b ≤ 0.5, 0.1 ≤ c ≤ 0.5, and 0.1 ≤ d ≤ 0.5.

[0064] In some embodiments of the present disclosure, the sodium battery cathode material is a single-crystal particle. Compared with a polycrystal structure of the sodium battery cathode material, the single-crystal structure of the sodium battery cathode material particle has high crystallinity and a more stable bulk structure, and has more excellent cycle performance. In addition, the above preparation method provided in some embodiments of the present disclosure is more likely to obtain a sodium battery cathode material with a high proportion of single-crystal particles.

[0065] In some embodiments of the present disclosure, the particle size distribution of the sodium battery cathode material satisfies: (D v 90-D v 10) / D v 50<1.35; wherein, D v 10, D v 50, D v90 respectively represent particle sizes corresponding to 10%, 50%, and 90% of the cumulative volume distribution percentage of the particles of the sodium electrode material, D v 10, D v 50, and D v 90, all in units of μm.

[0066] “(D v 90-D v 10) / D v 50” can be referred to as the particle size distribution dispersion of the sodium electrode material, and the smaller the value, the narrower the particle size distribution and the higher the particle size distribution concentration of the sodium electrode material, and the particles have no obvious abnormal morphology.

[0067] In some embodiments, (D v 90-D v 10) / D v 50 satisfies: (D v 90-D v 10) / D v 50≤1.32, (D v 90-D v 10) / D v 50≤1.30, (D v 90-D v 10) / D v 50≤1.28, or (D v 90-D v 10) / D v 50≤1.26, and the like.

[0068] In some embodiments of the present disclosure, D v 90 of the sodium electrode material can be less than 10 μm. In some embodiments, the D v 90 satisfies: D v 90≤9.5 μm, D v 90≤9.0 μm, D v 90≤8.5 μm, D v 90≤8.0 μm, and the like. The smaller D v 90 of the sodium electrode material can ensure that most of the particles of the sodium electrode material are not large in size and no abnormal agglomerates exist.

[0069] In some embodiments of the present disclosure, D v 99 of the sodium electrode material can be less than 15 μm, and in some embodiments, the D v 99 satisfies: D v 99≤14 μm, D v 99≤13 μm, D v 99≤12 μm, Dv 99≤ 11 pm, etc.

[0070] In some embodiments of the present disclosure, the D v 100 is less than 15 pm; wherein, D v 100 represents a particle size value corresponding to a cumulative volume distribution percentage of 100% of the sodium battery cathode material. In some embodiments, the D v 100 satisfies: D v 100≤ 14 pm, D v 100≤ 13 pm, D v 100≤ 12 pm, etc.

[0071] For example, according to GB / T 19077-2016 “Particle Size Analysis-Laser Diffraction Method”, a Malvern laser particle size analyzer can be used to perform laser particle size testing on the dried sodium battery cathode material to obtain the particle size distribution curve of the material, and the above D v 10, D v 50, D v 90, D v 99, and D v 100 values can be read from the particle size distribution curve. In addition, it should be noted that when the above sodium battery cathode material only includes the above sodium-based nickel-iron-manganese-zinc quaternary metal oxide, the relevant particle size distribution data of the above sodium battery cathode material is the particle size distribution data of the sodium-based nickel-iron-manganese-zinc quaternary metal oxide.

[0072] In some embodiments of the present disclosure, the crystal phase of the sodium battery cathode material includes a sodium nickel-iron-manganese oxide phase and a zinc oxide phase in the X-ray diffraction (XRD) spectrum of the sodium battery cathode material. For example, the sodium nickel-iron-manganese oxide phase is an O3 phase in space group which can provide capacity, and the zinc oxide phase does not provide capacity.

[0073] In some embodiments of the present disclosure, the mass percentage content of the zinc oxide phase in the crystal phase of the sodium battery cathode material is less than or equal to 1.5 wt%. The content of the zinc oxide phase which does not provide capacity in the total crystal phase of the sodium battery cathode material is low, which is beneficial to ensure that the overall gravimetric capacity of the sodium battery cathode material is high.

[0074] In some embodiments, the first mass percentage content of the zinc oxide phase in the crystal phase of the sodium battery cathode material satisfies: the first mass percentage content≤ 1.4 wt%, the first mass percentage content≤ 1.3 wt%, the first mass percentage content≤ 1.2 wt%, the first mass percentage content≤ 1.1 wt%, the first mass percentage content≤ 1.0 wt%, or the first mass percentage content≤ 0.9 wt%, etc.

[0075] In some embodiments of the present disclosure, the mass percentage content of the sodium nickel manganese iron oxide phase in the crystal phase of the sodium battery positive electrode material is greater than or equal to 98.5%. The high content of the sodium nickel manganese iron oxide phase in the total crystal phase of the sodium battery positive electrode material indicates that the content of impurity phases in the sodium battery positive electrode material is low, which is conducive to the high overall specific capacity of the sodium battery positive electrode material.

[0076] For example, the second mass percentage content of the sodium nickel manganese iron oxide phase in the crystal phase of the sodium battery positive electrode material satisfies: the second mass percentage content is greater than or equal to 98.6%, the second mass percentage content is greater than or equal to 98.7%, the second mass percentage content is greater than or equal to 98.8%, the second mass percentage content is greater than or equal to 98.9%, the second mass percentage content is greater than or equal to 99.0%, or the second mass percentage content is greater than or equal to 99.1%, etc.

[0077] For example, the method for obtaining the content of the zinc oxide phase and the sodium nickel manganese iron oxide phase in the crystal phase of the sodium battery positive electrode material includes: testing the sodium battery positive electrode material by using an X-ray diffractometer to obtain an XRD spectrum; comparing the obtained XRD spectrum with a standard phase PDF card to determine the types of each crystal; and performing Rietveld refinement on the XRD test result data corresponding to each crystal to calculate the content of each crystal phase in the sodium battery positive electrode material.

[0078] For example, the XRD test of the sodium battery positive electrode material can be performed according to JY / T 0587-2020 General Methods for Polycrystalline X-ray Diffraction.

[0079] Some embodiments of the present disclosure also provide a sodium ion battery 1000, as shown in FIG. 9, which includes the above-mentioned sodium battery positive electrode material 100. For example, the positive electrode of the sodium ion battery 1000 includes the above-mentioned sodium battery positive electrode material.

[0080] In some embodiments of the present disclosure, the sodium ion battery can include a positive electrode, a negative electrode, and a separator and an electrolyte between the positive electrode and the negative electrode. For example, the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one side surface of the positive electrode current collector, and the positive electrode active material layer includes the above-mentioned sodium battery positive electrode material, a binder, and a conductive agent of some embodiments of the present disclosure.

[0081] For example, the binder can include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyimide (PI), polyacrylic acid (PAA), polyacrylonitrile (PAN), polyacrylate (such as polymethyl methacrylate, polymethyl acrylate, polyethyl acrylate, etc.), polyolefin (such as polypropylene, polyethylene, etc.), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose (CMC-Na), sodium alginate, etc., but is not limited thereto.

[0082] For example, the conductive agent can include one or more of conductive carbon black (such as acetylene black, ketjen black, Supper P, 350G carbon black, etc.), carbon fiber, carbon nanotube, graphene, etc., but is not limited thereto.

[0083] For example, the positive current collector can be an aluminum foil, a carbon-coated aluminum foil, an aluminum-plated polymer film, etc.

[0084] Similar to the structure of the positive electrode, the negative electrode generally includes a negative current collector and a negative active material layer disposed on the negative current collector; the negative active material layer includes a negative active material, a binder, and a conductive agent. For example, the negative active material commonly used in sodium-ion batteries is generally hard carbon.

[0085] Since the positive electrode of the sodium-ion battery contains the above-mentioned sodium battery positive electrode material of some embodiments of the present disclosure, the sodium-ion battery has excellent electrochemical performance, such as high specific capacity in the first charge, high first charge-discharge efficiency, good cycle performance, and good rate performance, etc. The sodium-ion battery can be applied to an electrical device to supply power to it. The sodium-ion battery can also be applied to an energy storage system. For example, the electrical device can be a computer, a communication and consumer electronics (3C) product (such as a mobile phone, a notebook computer, a tablet computer, a wearable device, etc.), or an electric vehicle (such as an electric vehicle, an electric bicycle, etc.).

[0086] The embodiments of the present disclosure will be further described below in conjunction with multiple embodiments.

[0087] Embodiment 1

[0088] A preparation method of a sodium battery positive electrode material, comprising the following steps:

[0089] (1) Preparation of a nickel-iron-manganese ternary hydroxide precursor:

[0090] According to the molar ratio of Ni, Fe, and Mn elements of 0.25:0.375:0.375, nickel sulfate, iron sulfate, and manganese sulfate were weighed and mixed in water to prepare a nickel-iron-manganese metal salt solution;

[0091] Water was added to a reaction kettle, the stirring speed was set to 700 r / min, the temperature was raised to 60°C, and nitrogen was continuously introduced as a protective gas; an ammonia solution with a concentration of 0.3 mol / L was added to the reaction kettle as a complexing agent, and a sodium hydroxide solution was added as a precipitating agent to adjust the pH in the kettle to 11;

[0092] The prepared nickel-iron-manganese metal salt solution, the complexing agent, and the precipitating agent are continuously added into the reactor to perform a co-precipitation reaction. After the metal salt solution is completely consumed, the obtained reaction material is centrifuged to obtain a solid product, and the solid product is washed and dried to obtain a nickel-iron-manganese hydroxide precursor Ni 0.25 Fe 0.375 Mn 0.375 (OH)2.

[0093] (2) Preparation of sodium-based quaternary metal oxide:

[0094] 80 g of the nickel-iron-manganese ternary hydroxide, 9.7 g of ZnO, and 53 g of Na2CO3 are weighed and uniformly mixed in a mixer to obtain a mixture. The mixture is placed in a crucible and sintered in a tube furnace, with the sintering temperature being controlled at 950°C, the holding time being 12 h, and the temperature rising rate from room temperature to the sintering temperature being 5°C / min.

[0095] After the sintering is completed, the sintered product is crushed, sieved through a 200-mesh sieve, and qualified by removing magnetism to obtain the required sodium-based nickel-iron-manganese-zinc quaternary metal oxide positive electrode material, with the chemical formula of the positive electrode material being NaNi 0.22 Zn 0.12 Fe 0.33 Mn 0.33 O2.

[0096] The SEM photo of the positive electrode material prepared in some embodiments of the present disclosure is shown in FIG. 1. As can be seen from FIG. 1, the positive electrode material is a single crystal particle with high morphology consistency and no abnormal large particles.

[0097] Example 2

[0098] (1) Preparation of nickel-iron-manganese ternary hydroxide precursor: same as Example 1;

[0099] (2) Preparation of sodium-based quaternary metal oxide:

[0100] 83 g of the nickel-iron-manganese ternary hydroxide, 6.5 g of ZnO, and 47.7 g of Na2CO3 are weighed and uniformly mixed in a mixer to obtain a mixture. The mixture is placed in a crucible and sintered in a tube furnace, with the sintering temperature being controlled at 950°C, the holding time being 12 h, and the temperature rising rate from room temperature to the sintering temperature being 5°C / min.

[0101] After the sintering is completed, the sintered product is crushed, sieved through a 200-mesh sieve, and qualified by removing magnetism to obtain the required sodium-based nickel-iron-manganese-zinc quaternary metal oxide positive electrode material, with the chemical formula of the positive electrode material being NaNi 0.9 Ni 0.23 Zn0.08 Fe 0.345 Mn 0.345 O2.

[0102] For example, the SEM photos of the positive electrode material prepared in some embodiments of the present disclosure are shown in FIG. 2. As can be seen from FIG. 2, the positive electrode material is single crystal particles, and has high morphology consistency and no abnormal large particles.

[0103] Example 3

[0104] (1) Preparation of a nickel-iron-manganese ternary hydroxide precursor: same as in Example 1;

[0105] (2) Preparation of a sodium-based quaternary metal oxide:

[0106] 83 g of the above nickel-iron-manganese ternary hydroxide, 6.5 g of ZnO and 53 g of Na2CO3 were weighed out, mixed uniformly in a mixer to obtain a mixture; the mixture was placed in a crucible and placed in a tube furnace for sintering, the sintering temperature was controlled at 950℃, the holding time was 12 h, and the temperature rising rate from room temperature to the sintering temperature was 5℃ / min.

[0107] After sintering, the sintered product was crushed, passed through a 200 mesh sieve, and qualified after removing the magnetism to obtain the desired sodium-based nickel-iron-manganese-zinc quaternary metal oxide positive electrode material, and the chemical formula of the positive electrode material was NaNi 0.23 Zn 0.08 Fe 0.345 Mn 0.345 O2.

[0108] For example, the SEM photos of the positive electrode material prepared in some embodiments of the present disclosure are shown in FIG. 3. As can be seen from FIG. 3, the positive electrode material is single crystal particles, and has high morphology consistency and no abnormal large particles.

[0109] Example 4

[0110] (1) Preparation of a nickel-iron-manganese ternary hydroxide precursor:

[0111] Nickel sulfate, iron sulfate and manganese sulfate were weighed out according to the molar ratio of Ni, Fe and Mn elements of 0.25:0.34:0.41, and mixed in water to prepare a nickel-iron-manganese metal salt solution;

[0112] Water was added to a reaction kettle, the stirring speed was set to 700 r / min, the temperature was raised to 60℃, and nitrogen was continuously introduced as a protective gas; an ammonia solution with a concentration of 0.3 mol / L was added to the reaction kettle as a complexing agent, and a sodium hydroxide solution was added as a precipitating agent to adjust the pH in the kettle to 11;

[0113] The prepared nickel-iron-manganese metal salt solution, the complexing agent, and the precipitating agent are continuously added into the reactor to perform a co-precipitation reaction. After the metal salt solution is completely consumed, the obtained reaction material is centrifuged to obtain a solid product, and the solid product is washed and dried to obtain a nickel-iron-manganese hydroxide precursor Ni 0.25 Fe 0.34 Mn 0.41 (OH)2.

[0114] (2) Preparation of sodium-based quaternary metal oxide:

[0115] 80 g of the above nickel-iron-manganese ternary hydroxide, 9.7 g of ZnO, and 53 g of Na2CO3 are weighed and uniformly mixed in a mixer to obtain a mixture. The mixture is placed in a crucible and placed in a tube furnace for sintering. The sintering temperature is controlled at 900°C, the holding time is 10 h, and the temperature rising rate from room temperature to the sintering temperature is 5°C / min.

[0116] After the sintering is completed, the sintered product is crushed, sieved through a 200-mesh sieve, and qualified by removing magnetism to obtain the required sodium-based nickel-iron-manganese-zinc quaternary metal oxide positive electrode material. The chemical formula of the positive electrode material is NaNi 0.22 Zn 0.12 Fe 0.30 Mn 0.36 O2.

[0117] The SEM photo of the positive electrode material prepared in some embodiments of the present disclosure is shown in FIG. 4. As can be seen from FIG. 4, the positive electrode material is a single crystal particle with high morphology consistency and no abnormal large particles.

[0118] To highlight the beneficial effects of the technical solutions in some embodiments of the present disclosure, the following comparative examples are also provided.

[0119] Comparative Example 1

[0120] The sodium-based nickel-iron-manganese-zinc quaternary metal oxide positive electrode material is prepared by a solid phase method, for example, including the following steps:

[0121] 16.5 g of NiO, 26.4 g of Fe2O3, 25.2 g of Mn3O4, 9.7 g of ZnO, and 53 g of Na2CO3 are uniformly mixed in a mixer to obtain a mixture. The mixture is placed in a crucible and placed in a tube furnace for sintering. The sintering temperature is controlled at 950°C, the holding time is 12 h, and the temperature rising rate from room temperature to the sintering temperature is 5°C / min.

[0122] After the sintering is completed, the obtained sintered product is crushed, passed through a 200-mesh screen, and qualified by removing magnetism to obtain the required sodium-based nickel-iron-manganese-zinc quaternary metal oxide positive electrode material, the chemical formula of which is represented as NaNi 0.22 Zn 0.12 Fe 0.33 Mn 0.33 O2, consistent with the positive electrode material of Example 1.

[0123] For example, the SEM photo of the positive electrode material prepared in Comparative Example 1 is shown in FIG. 5. As can be seen from FIG. 5, the morphology consistency of the positive electrode material prepared in Comparative Example 1 is low, the particle size distribution is uneven, there are abnormally large particles, and there are also some small particle agglomerates, suspected of being amorphous material.

[0124] Comparative Example 2

[0125] A quaternary sodium electrode positive electrode material is prepared by a quaternary hydroxide precursor sintering method, for example, including the following steps:

[0126] (1) Preparation of nickel-zinc-iron-manganese quaternary hydroxide precursor:

[0127] Nickel sulfate, iron sulfate, manganese sulfate, and zinc sulfate are weighed according to the molar ratio of Ni, Zn, Fe, and Mn elements of 22:12:33:33, and mixed in water to prepare a nickel-zinc-iron-manganese metal salt solution;

[0128] Water is added to the reaction kettle, the stirring speed is set to 700 r / min, the temperature is raised to 60°C, and nitrogen gas is continuously introduced as a protective gas; ammonia solution with a concentration of 0.3 mol / L is added to the reaction kettle as a complexing agent, and sodium hydroxide solution is added as a precipitating agent to adjust the pH in the kettle to 11;

[0129] Then the above prepared nickel-zinc-iron-manganese metal salt solution, complexing agent, and precipitating agent are continuously added to the above reaction kettle for co-precipitation reaction; after the above metal salt solution is completely consumed, the obtained reaction material is centrifuged to obtain a solid product, and the solid product is washed and dried to obtain a nickel-zinc-iron-manganese hydroxide precursor, the chemical formula of which is Ni 0.22 Zn 0.12 Fe 0.33 Mn 0.33 (OH)2.

[0130] (2) Preparation of sodium-based quaternary metal oxide:

[0131] 92g of the above nickel-zinc-iron-manganese quaternary hydroxide and 53g of Na2CO3 were mixed uniformly in a mixer to obtain a mixture; the mixture was placed in a crucible and placed in a tube furnace for sintering, the sintering temperature was controlled at 1000℃, the holding time was 12h, and the temperature rising rate from room temperature to the sintering temperature was 5℃ / min.

[0132] After the sintering was completed, the sintered product was crushed, sieved through a 200-mesh sieve, and qualified after removing the magnetism, to obtain the desired sodium-based nickel-iron-manganese-zinc quaternary metal oxide positive electrode material, the chemical formula of the positive electrode material was NaNi 0.22 Zn 0.12 Fe 0.33 Mn 0.33 O2.

[0133] For example, the SEM photo of the positive electrode material prepared in Comparative Example 2 is shown in FIG. 6. As can be seen from FIG. 6, the morphology consistency of the positive electrode material prepared in Comparative Example 2 is low, and there are abnormally large particles.

[0134] Particle size test:

[0135] The powder samples of the sodium battery positive electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 were mixed with 10mL of alcohol respectively, and ultrasonic dispersion was performed for 3 minutes to obtain a dispersion liquid, 5mL of the dispersion liquid was taken by a pipette and added into 500mL of deionized water, and a Malvern laser particle size analyzer was used for particle size test, and the test results are shown in Table 1 below.

[0136] Phase structure analysis:

[0137] The powder samples of the sodium battery positive electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 were added to a glass sample plate respectively for XRD test by a forward method, and the XRD spectra of the powder samples were obtained; CuKɑ line (wavelength of 1.5418A) was used for the test, radius of the goniometer was 300mm, the scanning angle range was 5°-90°, and the scanning speed was 5° / min. The unit cell was refined for the XRD spectra of each positive electrode material sample, and the refinement results are shown in Table 1 below. The XRD spectrum of the positive electrode material of Example 1 is shown in FIG. 7.

[0138] Table 1 Particle size test results and XRD test results of each positive electrode material Note: In Table 1, the dispersity = (D v 90-D v 10) / D v ​50. Note: In Table 1, the space group of the zinc oxide phase is attributed to: 186: P63mc, the DB card number is: 00-005-0664; the space group of the sodium nickel zinc ferrimanganese acid phase is attributed to: 166: R-3m, hexagonal phase. In addition, when performing XRD refinement, there is no standard card of sodium nickel zinc ferrimanganese acid in the standard card library, and the crystal structure of NaMn 0.35 Fe 0.3 Ni 0.35 O2 standard card is used instead to perform fitting, and the DB card number of the standard card is: 01-090-2260.

[0139] From the particle size distribution results in Table 1, it can be seen that the particle size distribution of the sodium battery positive electrode material of Example 1 is narrow, and the dispersion is low. The morphology consistency of the sodium battery positive electrode materials of Comparative Examples 1 and 2 is poor, and the D v 100 of the sodium battery positive electrode materials of Comparative Examples 1 and 2 is obviously larger, and the particle size test results are consistent with their SEM test results.

[0140] From the XRD refinement results in Table 1, it can be seen that the crystal phases of the sodium battery positive electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 are all composed of Na(Ni 0.3 Fe 0.4 Mn 0.3 )O2 and ZnO phases of O3 phase, the content of ZnO phase in the positive electrode materials of Examples 1-4 is very low, below 1.5%, and the purity of Na(Ni 0.3 Fe 0.4 Mn 0.3 )O2 phase is very high, above 98.5%. ZnO does not provide capacity in sodium ion batteries, and the positive electrode materials of Comparative Examples 1-2 all contain a higher ZnO impurity phase, which is expected to be detrimental to the capacity of the positive electrode material.

[0141] Preparation and performance test of button cell:

[0142] The sodium battery positive electrode materials prepared in Examples 1-4 and Comparative Examples 1-2 were mixed with conductive agent acetylene black and binder PVDF in a mass ratio of 8:1:1 in solvent N-methyl pyrrolidone (abbreviated as NMP), stirred uniformly, and positive electrode slurry was prepared; the positive electrode slurry was coated on an aluminum foil current collector, then placed in a vacuum drying oven for drying for 12 hours to form a positive electrode active material layer on the aluminum foil, and an unpressed positive electrode sheet was obtained; the unpressed positive electrode sheet was pressed and cut into positive electrode sheets of the same size with a sheet cutting machine. Then, in a nitrogen-filled glove box, the above positive electrode sheet, separator and metal sodium sheet were stacked in order in a button stainless steel shell, and electrolyte was injected, and after packaging, a button sodium battery was obtained.

[0143] The assembled each button sodium battery was subjected to the following electrochemical performance test, and the results were summarized in Table 2 below.

[0144] 1) First circle coulombic efficiency test: at 25°C, each button sodium battery was charged at 0.1C constant current to the cut-off voltage of 4V, and then charged at 4V constant voltage to the cut-off current of 0.05C; after resting, it was discharged at 0.1C constant current to 2V. The first circle charge capacity and the first circle discharge capacity were recorded, wherein the first circle coulombic efficiency was equal to the first circle discharge capacity divided by the first circle charge capacity.

[0145] 2) Discharge rate performance test: at 25°C, each button sodium battery was charged at 0.2C constant current to the cut-off voltage of 4V, and then charged at 4V constant voltage to the cut-off current of 0.05C; then the battery was discharged at 0.2C to the voltage of 2.0V, and the discharge capacity C1 was recorded.

[0146] Then each button sodium battery was charged at 0.2C constant current to the cut-off voltage of 4V, and then charged at 4V constant voltage to the cut-off current of 0.05C; then the battery was discharged at 5C to the voltage of 2.0V, and the discharge capacity C2 was recorded. The discharge rate performance of the battery can be measured by C2 / C1.

[0147] 3) Cycle performance test: at 25°C, each button sodium battery was charged at 1C constant current to the cut-off voltage of 4V, and then charged at 4V constant voltage to the cut-off current of 0.05C; then the battery was discharged at 1C to the voltage of 2.0V, and the discharge capacity C1 was recorded; then each button sodium battery was cycled 100 times by the same operation, and the discharge capacity of the battery after the 100th cycle was recorded as C2; the cycle performance of the battery can be measured by C2 / C1*100%.

[0148] Table 2 summarizes the test results of the button sodium batteries of each example and comparative example

[0149] From Table 2, it can be known that compared with the button sodium batteries of Comparative Examples 1-2, the button sodium batteries prepared by using the positive electrode materials of some embodiments 1-4 of the present disclosure have more excellent electrochemical performance, higher first circle coulombic efficiency, better rate performance, and better cycle capacity retention at room temperature, which may be mainly due to the high consistency of the morphology of the single crystal particles, the uniform particle size distribution, and the high phase purity of the positive electrode materials provided by embodiments 1-4.

[0150] The above-described embodiments only express several exemplary embodiments of the present disclosure, and the description is more detailed, but it cannot be understood as a limitation on the scope of the patent of the present disclosure. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present disclosure, a number of modifications and improvements can be made, which are within the protection scope of the present disclosure.

Claims

1. A sodium electro-positive cathode material, comprising: A sodium-based nickel-iron-manganese-zinc quaternary metal oxide; wherein the crystal phase of the sodium-based positive electrode material comprises a zinc oxide phase with a mass percentage of less than or equal to 1.5 wt%, and the particle size distribution of the sodium-based positive electrode material satisfies: (D v 90-D v 10) / D v 50<1.35; wherein D v 10, D v 50, D v 90 represents the particle size corresponding to the cumulative volume distribution percentage of 10%, 50%, and 90% of the sodium cathode material, respectively; D v 10, D v 50, D v 90, each in units of μm.

2. The sodium electric cathode material of claim 1, wherein, D v 100 less than 15 μm; wherein, D v 100 represents the particle size value corresponding to the cumulative volume distribution percentage of the sodium electric positive electrode material reaching 100%.

3. The sodium electric cathode material of claim 1, wherein, D of the sodium electric cathode material is less than 10 pm. v 90 less than 10 pm.

4. The sodium electro-positive cathode material of any one of claims 1-3, wherein, The crystal phase of the sodium electric positive electrode material includes a sodium nickel iron manganese acid phase and the zinc oxide phase; wherein the mass percentage content of the sodium nickel iron manganese acid phase in the crystal phase of the sodium electric positive electrode material is greater than or equal to 98.5%.

5. The sodium electro-positive cathode material of claim 1 or 4, wherein, The mass percentage content of the zinc oxide phase in the crystal phase of the sodium electric positive electrode material is less than or equal to 1.0wt%.

6. The sodium electro-positive cathode material of any one of claims 1-5, wherein, The sodium electric positive electrode material is a single crystal particle.

7. The sodium electro-positive cathode material of any one of claims 1-6, wherein, The chemical formula of the sodium-based quaternary metal oxide includes Na w Ni a Zn b Fe c Mn d O2, wherein 0.67≤w≤1.2, 0 a <1, 0 b <1, 0 c <1, a+b+c+d=1.

8. The sodium electric cathode material of claim 7, wherein, 0.1≤a≤0.5, 0.1≤b≤0.5, 0.1≤c≤0.5, 0.1≤d≤0.5, a+b+c+d=1.

9. A preparation method of a sodium electric positive electrode material, comprising the following steps: mixing a nickel iron manganese ternary hydroxide precursor with a zinc source and a sodium source to obtain a mixture; and sintering the mixture to obtain a sodium-based nickel iron manganese zinc quaternary metal oxide.

10. The production method according to claim 9, wherein The zinc source includes one or more of zinc carbonate, zinc oxide and zinc hydroxide; and the sodium source includes one or more of sodium carbonate, sodium bicarbonate and sodium hydroxide.

11. The production method according to claim 9 or 10, wherein The sintering temperature is in the range of 500-1200℃, the sintering time is 5-20h, and the sintering atmosphere is at least one of oxygen or air.

12. A sodium ion battery comprising the sodium electric positive electrode material according to any one of claims 1-8, or comprising the sodium electric positive electrode material prepared by the preparation method according to any one of claims 9-11.

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