CN116613306B

CN116613306B - Layered oxide positive electrode material, preparation method thereof, positive electrode composition, sodium ion secondary battery and application

Info

Publication number: CN116613306B
Application number: CN202310868169.8A
Authority: CN
Inventors: 王建鑫; 程斯琪; 王伟刚; 李树军; 唐堃
Original assignee: Liyang Zhongke Haina Technology Co ltd
Current assignee: Liyang Zhongke Haina Technology Co ltd
Priority date: 2023-07-17
Filing date: 2023-07-17
Publication date: 2023-12-19
Anticipated expiration: 2043-07-17
Also published as: CN116613306A

Abstract

The invention relates to a layered oxide positive electrode material, a preparation method thereof, a positive electrode composition, a sodium ion secondary battery and application thereof. The layered oxide positive electrode material has a general formula Na _x Cu _a Mn _b Fe _c M _d O _e Wherein x=0.90-1.10, a=0.10-0.40, b=0.20-0.80, c=0.20-0.40, d=0-0.50, e=1.70-2.40, m is a doping element, and the volume average particle diameter of the layered oxide cathode material satisfies: d is less than or equal to 1.30 _v 10+D _v 90)/D _v 50 is less than or equal to 1.50, and the maximum particle diameter D of the layered oxide cathode material _max Less than or equal to 15.50 mu m; and the minimum particle diameter D of the layered oxide cathode material _min And more than or equal to 0.45 mu m. The layered oxide positive electrode material has good air stability, initial effect, rate discharge performance and cycle performance.

Description

Layered oxide positive electrode material, preparation method thereof, positive electrode composition, sodium ion secondary battery and application

Technical Field

The present invention relates generally to the field of energy storage technology, in particular to the field of sodium ion secondary batteries, and specifically relates to a layered oxide positive electrode material, a preparation method thereof, a positive electrode composition (for sodium ion secondary batteries) comprising the same, a sodium ion secondary battery comprising the positive electrode composition (for sodium ion secondary batteries), and use of the sodium ion secondary battery.

Background

Sodium ions have wide application in many fields such as power generation, communication base station construction, and the like. The sodium ion battery has a similar structural principle to the lithium ion battery and works through repeated deintercalation, transfer and transmission of sodium ions between the anode and the cathode. Compared with a lithium ion battery, the sodium ion battery has great cost advantages. On one hand, the sodium ion positive electrode material uses sodium element with abundant reserves and low price, and under the same condition, the cost of the sodium ion positive electrode material is about 20-30% lower than that of the lithium ion positive electrode material. On the other hand, in the sodium ion battery, aluminum foil which is light in weight and low in price can be used for both the positive and negative electrodes without fear of Li/Al alloying occurring as in the lithium ion battery. In addition, the high-low temperature performance and the safety performance of the sodium ion battery are obviously superior to those of the lithium ion battery. In addition, the processes of the production, the supply, the battery processing, the assembly, the module assembly, the matching and the like of the main raw materials of the sodium ion battery are compatible with all links of the lithium ion battery industry to a great extent. For the above reasons, sodium ion batteries have been developed very rapidly in recent years, and are expected to be a popular place in the field of energy storage at low cost and on a scale required by extreme charge and discharge conditions. However, the mass energy density of the sodium ion battery is greatly different from that of the lithium ion battery at present.

In order to improve the mass energy density of sodium ion batteries, a great deal of research is conducted, and it is found that among various sodium ion battery positive electrode materials, a layered oxide positive electrode material has high mass energy density and charge-discharge capacity, and the preparation process is simple, so that the layered oxide positive electrode material becomes one of the materials with the most commercialized potential. However, it has been found that the air stability of the layered oxide cathode material is poor, which greatly limits the mass production application of the layered oxide cathode material, and increases the investment in the production process, such as a fully-closed low-humidity production environment; stringent process parameters; fluctuation of product performance, etc. For example, when placed in air, the surface of the layered oxide cathode material particles and H in air ₂ O、CO ₂ A series of complex reactions occur to generate alkaline substances such as sodium carbonate, sodium hydroxide and the like, thus bringing about new processing technology problems, for exampleSuch as homogenized gel, poor toughness of pole pieces, etc. In addition, the first effect (i.e., first coulombic efficiency), rate discharge performance, and cycle performance of the prior art layered oxide cathode materials are still unsatisfactory.

In view of the foregoing, a need exists for a new layered oxide cathode material that has good air stability, as well as initial efficiency, rate discharge performance, and cycle performance.

Disclosure of Invention

The present invention has been made keeping in mind the above problems occurring in the prior art.

In a first aspect, the present invention relates to a layered oxide cathode material having the general formula:

Na _x Cu _a Mn _b Fe _c M _d O _e

wherein x is more than or equal to 0.90 and less than or equal to 1.10,0.10, a is more than or equal to 0.40,0.20 and less than or equal to 0.80, c is more than or equal to 0.20 and less than or equal to 0.40,0 and less than or equal to d is more than or equal to 0.50,1.70 and e is more than or equal to 2.40, and the value of x and a, b, c, d, e ensures that the general formula meets the valence balance;

m is selected from one or more of Mg, al, si, ti, cr, co, ni, zn, Y, zr, sb, la, ce, W, F, preferably one or more of Mg, al, ti, zn, Y, zr, F, more preferably one or more of Mg, al, ti, zr, F;

wherein the layered oxide positive electrode material D _v 10 particle size, D _v 50 particle size and D _v The 90 particle size satisfies: d is less than or equal to 1.30 _v 10+D _v 90)/D _v 50≤1.50，

Maximum particle diameter D of the layered oxide cathode material _max Less than or equal to 15.50 mu m; and

minimum particle diameter D of the layered oxide cathode material _min ≥0.45μm。

In a second aspect, the present invention relates to a method for preparing a layered oxide cathode material according to the first aspect of the present invention, comprising the steps of:

step a: uniformly mixing a Na source, a Cu source, a Mn source, a Fe source and an optional M source according to stoichiometric ratio to obtain a mixture precursor;

Step b: sintering the precursor obtained in the step a; and

step c: cooling the product obtained in the step b, optionally crushing and sieving.

In a third aspect, the present invention relates to a positive electrode composition for a sodium ion secondary battery, comprising the layered oxide positive electrode material according to the first aspect of the present invention.

In a fourth aspect, the present invention relates to a sodium ion secondary battery comprising the positive electrode composition according to the third aspect of the present invention.

In a fifth aspect, the present invention relates to the use of a sodium ion secondary battery of the fourth aspect of the present invention in an energy storage device for solar power generation, wind power generation, smart grid peaking, distribution power station, backup power supply or communication base station.

The inventors have unexpectedly found that by controlling the composition of the layered oxide cathode material (D) _v 10+D _v 90)/D _v 50、D _max And D _min The air stability, the first effect, the rate discharge performance and the cycle performance of the layered oxide cathode material can be obviously improved within the range defined by the invention.

Drawings

In order to more clearly illustrate the technical solution of the present invention, the drawings required for describing the embodiments will be briefly described below. It should be understood that these drawings are merely for the purpose of facilitating easier understanding of the present invention by the skilled person and are not intended to limit the scope of the present invention.

Fig. 1 is a scanning electron microscope picture of a layered oxide cathode material prepared in example 1 of the present invention.

Fig. 2 is a scanning electron microscope picture of a layered oxide cathode material prepared in example 3 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantageous technical effects of the present application clearer, the present application will be described in detail below. It should be noted that the various aspects, features, embodiments, and advantages thereof described herein may be compatible and/or may be combined together.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The present invention relates to a layered oxide positive electrode material, a method for producing the same, a positive electrode composition (for sodium ion secondary batteries) comprising the same, a sodium ion secondary battery comprising the positive electrode composition (for sodium ion secondary batteries), and use of the sodium ion secondary battery.

The present invention will be specifically described below.

Layered oxide positive electrode material

Na _x Cu _a Mn _b Fe _c M _d O _e

Regarding the air stability of sodium-ion layered oxide cathode materials, it is generally recognized in the art that H in air when placed in air ₂ O is embedded between transition metal layers along crystal planes, and separation occurs between the layers, which macroscopically appears as microcracks. In addition, replacementActing to make in-layer Na ⁺ Is separated from CO on the surface of the material ₂ After the reaction, na is generated ₂ CO ₃ . The above-mentioned action is due to Na ₂ CO ₃ The inter-layer separation is further deteriorated, and macroscopically represented by pulverization of the material. With H in air ₂ O and CO ₂ The above-mentioned effects of the layered oxide cathode material will deteriorate the air stability.

In addition, the initial efficiency, rate discharge performance and cycle performance of the layered oxide cathode material in the prior art are still unsatisfactory.

The inventors have unexpectedly found during the course of the study that, when the control of the layer oxide cathode material (D _v 10+D _v 90)/D _v 50、D _max And D _min Within the specific range defined by the present invention, the air stability and the first effect, rate discharge performance and cycle performance ratio (D _v 10+D _v 90)/D _v 50、D _max And D _min Performance improvement when any one of these is not within this specific range, and thus it is possible to provide a layered oxide cathode material having superior air stability, initial efficiency, rate discharge performance and cycle performance as a whole in the art.

In the layered oxide cathode material of the present invention, D of the layered oxide cathode material _v The 10 particle diameter means that the particles smaller than the particle diameter value account for 10% of the total sample volume in the volume cumulative distribution curve of the layered oxide cathode material, and the particles larger than the particle diameter value account for 90% of the total sample volume. Similarly, D _v The 50 particle size refers to that particles smaller than the particle size value and larger than the particle size value respectively account for 50% of the total sample volume in the volume accumulation distribution curve of the layered oxide cathode material; d (D) _v The particle diameter of 90 means that particles with a volume cumulative distribution curve smaller than the particle diameter value of the layered oxide cathode material account for 90% of the total sample volume, and particles with a particle diameter value larger than the particle diameter value account for 10% of the total sample volume; d (D) _max Refers to the maximum (maximum) particle size in the volume cumulative distribution curve of the layered oxide cathode material; and D _min Refers to the smallest (minimum) particle size in the volume cumulative distribution curve of the layered oxide cathode material.

In the layered oxide cathode material of the present invention, D of the layered oxide cathode material _v 10 particle size, D _v 50 particle size and D _v The 90 particle size satisfies: d is less than or equal to 1.30 _v 10+D _v 90)/D _v 50 is less than or equal to 1.50. For example (D) _v 10+D _v 90)/D _v 50 may be within a range defined by 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, 1.50, or any two thereof.

In the layered oxide cathode material of the present invention, the layered oxide cathode material has a maximum particle diameter D _max 15.50 μm or less, e.g. D _max Less than or equal to 15.00 μm, as D _max Less than or equal to 14.00 mu m or D _max 13.00. Mu.m, in particular 11.50. Mu.m, D _max And is less than or equal to 14.50 mu m. For example, D _max May be 15.50, 15.40, 15.30, 15.20, 15.10, 15.00, 14.90, 14.80, 14.70, 14.60, 14.50, 14.40, 14.30, 14.20, 14.10, 14.00, 13.90, 13.80, 13.70, 13.60, 13.50, 13.40, 13.30, 13.20, 13.10, 13.00, 12.90, 12.80, 12.70, 12.60, 12.50, 12.40, 12.30, 12.20, 12.10, 12.00, 11.90, 11.80, 11.70, 11.60, 11.50, 11.40, 11.30, 11.20, 11.10, 11.00, 10.90, 10.80, 10.70, 10.60, 10.50, 10.40, 10.30, 10.20, 10.10.10 or 10.00 μm.

In the layered oxide cathode material of the present invention, the layered oxide cathode material has a minimum particle diameter D _min 0.45 μm, e.g. D _min ≥0.50μm，D _min More than or equal to 0.80 mu m, and as more than or equal to 0.80 mu m and less than or equal to D _min Less than or equal to 1.55 mu m. For example, D _min May be 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.03, 1.04, 1.1.1.11, 1.08, 1.11, 1.7, 1.1.05, 1.11, 1.9, 1.7, 1.9 and 1.91.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.73, 1.74, 1.75, 1.76, 1.77, 1.78, 1.79, 1.80, 1.81, 1.82, 1.83, 1.84, 1.85, 1.86, 1.87, 1.88, 1.89, 1.90, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.98, 1.99 or 2.00 μm.

In some embodiments, the layered oxide cathode material of the present invention is a single crystal material.

The inventors have found that when the layered oxide cathode material of the present invention satisfies one or more of the following conditions, one or more of the air stability and the first effect, the rate discharge performance, or the cycle performance of the obtained layered oxide cathode material can be further improved.

In some embodiments, the layered oxide cathode material D _v The 10 particle size is 0.60-2.20 μm, for example 0.80-2.10 μm or 0.80-1.90 μm. For example, D _v 10 have a particle size of 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.9, 1.7, 1.03, 1.04, 0.0.05 and 10. 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, 1.71, 1.72, 1.73, 1.74, 1.75 1.76, 1.77, 1.78, 1.79, 1.80, 1.81, 1.82, 1.83, 1.84, 1.85, 1.86, 1.87, 1.88, 1.89, 1.90, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.98, 1.99, 2.00, 2.01, 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 2.08, 2.09, 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19, 2.20 μm, or any two thereof.

In some embodiments, the layered oxide cathode material D _v The 50 particle size is 2.00-8.00. Mu.m, for example 2.50-7.00. Mu.m, or 3.00-7.00. Mu.m. The inventors have found in the study that when the layered oxide cathode material of the present invention is D _v When the 50-grain diameter is 2.00-8.00 mu m, the capacity exertion is further improved, and the energy consumption of high-temperature sintering in the preparation process is further reduced. For example, D _v 50 having a particle size of 2.00, 2.10, 2.20, 2.30, 2.40, 2.50, 2.60, 2.70, 2.80, 2.90, 3.00, 3.10, 3.20, 3.30, 3.40, 3.50, 3.60, 3.70, 3.80, 3.90, 4.00, 4.10, 4.20, 4.30, 4.40, 4.50, 4.60, 4.70, 4.80, 4.90, 5.00, 5.10, 5.20, 5.30, 5.40, 5.50, 5.60, 5.70, 5.80, 5.90, 6.00, 6.10, 6.20, 6.30, 6.40, 6.50, 6.60, 6.70, 6.80, 6.90, 7.00, 7.10, 7.20, 7.30, 7.40, 7.50, 7.60, 7.70, 7.80, 7.90, 8.70, 8.00, or any two of these ranges.

In some embodiments, the layered oxide cathode material D _v The 90 particle size is 3.00 to 8.00. Mu.m, for example 3.40 to 7.50. Mu.m, or 3.50 to 7.50. Mu.m. For example, D _v The 90 particle size is 3.00, 3.10, 3.20, 3.30, 3.40, 3.50, 3.60, 3.70, 3.80, 3.90, 4.00, 4.10, 4.20, 4.30, 4.40, 4.50, 4.60, 4.70, 4.80, 4.90, 5.00, 5.10, 5.20, 5.30, 5.40, 5.50, 5.60, 5.70, 5.80, 5.90, 6.00, 6.10, 6.20, 6.30, 6.40, 6.50, 6.60, 6.70, 6.80, 6.90, 7.00, 7.10, 7.20, 7.30, 7.40, 7.50, 7.60, 7.70, 7.80, 7.90, 8.00 μm, or any two thereof.

In some embodiments, the layered oxide cathode material obtained by the present invention is spherical. The degree to which a material is spherical may be expressed by the sphericity of the material. Herein, sphericity refers to the ratio of the diameter of a circle equal to the projected area of an object to the diameter of a circle equal to the projected circumference of the object. For example, the sphericity phi of the layered oxide cathode material is not less than 0.55. For example, the sphericity phi is within a range defined by 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, or any two thereof.

In some embodiments, the layered oxide cathode material has a BET specific surface area of 0.10 to 0.60m ² /g, e.g. 0.10-0.55m ² /g or 0.10-0.35m ² And/g. For example, the BET specific surface area is 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60m ² /g, or any two thereof.

In some embodiments, in the XRD spectrum of the layered oxide cathode material, the ratio I003/I104 of the peak intensity (peak height or peak area) I003 peak to the peak intensity (peak height or peak area) I104 of the 104 peak is 1.30 to 1.70, for example 1.30 to 1.65 or 1.30 to 1.55. In this context, the "peak intensity" may refer to the intensity in terms of peak height, as well as the intensity in terms of peak area, provided that I003 and I104 simultaneously refer to the intensity in terms of peak height, or simultaneously refer to the intensity in terms of peak area. For example, I003/I104 represents a ratio of a peak height of a 003 peak to a peak height of a 104 peak, or a ratio of a peak area of a 003 peak to a peak area of a 104 peak. As an example, the ratio I003/I104 of the peak intensities (peak heights or peak areas) I003 of the 003 peaks to the peak intensities (peak heights or peak areas) I104 of the 104 peaks is within a range defined by 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.63, 1.64, 1.65, 1.66, 1.67, 1.68, 1.69, 1.70, or any two thereof.

In some embodiments, the layered oxide cathode material has a tap density TD (tap density) of from 1.80 to 2.50g/cm ³ For example 1.85-2.40g/cm ³ . For example, tap density TD is 1.80, 1.81, 1.82, 1.83, 1.84, 1.85, 1.86, 1.87, 1.88, 1.89, 1.90, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.98, 1.99, 2.00, 2.01, 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 2.08, 2.09, 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19, 2.20, 2.21, 2.22, 2.23, 2.24, 2.25, 2.26, 2.27, 2.28, 2.29, 2.30, 2.31, 2.32, 2.33, 2.34, 2.35, 2.36, 2.37, 2.38, 2.45, 2.46, 2.35, 2.38, 2.45/46, 2.45, 2.46, 2.35, 2.38, 2.45 and 2.45/46 ³ Or any two thereof.

In some embodiments, the layered oxide cathode material has a compacted density PD (pressure density) at 15kN of 2.80 to 3.50g/cm ³ For example 2.80-3.35g/cm ³ . For example, the number of the cells to be processed, the compacted density PD was 2.80, 2.81, 2.82, 2.83, 2.84, 2.85, 2.86, 2.87, 2.88, 2.89, 2.90, 2.91, 2.92, 2.93, 2.94, 2.95, 2.96, 2.97, 2.98, 2.99, 3.00, 3.01, 3.02, 3.03, 3.04, 3.05, 3.06, 3.07, 3.08, 3.09, 3.10, 3.11, 3.12, 3.13, 3.14 3.15, 3.16, 3.17, 3.18, 3.19, 3.20, 3.21, 3.22, 3.23, 3.24, 3.25, 3.26, 3.27, 3.28, 3.29, 3.30, 3.31, 3.32, 3.33, 3.34, 3.35, 3.36, 3.37, 3.38, 3.39, 3.40, 3.41, 3.42, 3.43, 3.44, 3.45, 3.46, 3.47, 3.48, 3.49, 3.50g/cm ³ Or any two thereof.

In the present invention, "tap density" and "compacted density" have meanings commonly understood in the art. The term "tap density" refers to the mass per unit volume measured after the powder in the container has been tapped under specified conditions. Similarly, the term "compacted density" refers to the mass per unit volume of powder in a container measured under specified conditions after compression at a pressure of 15 kN. The tap density and the compacted density are measured by the methods described in the examples.

In some embodiments, the difference PD-TD between the compacted density and tap density of the layered oxide cathode material satisfies: 0.40g/cm ³ ≤PD-TD≤1.70 g/cm ³ For example 0.40g/cm ³ ≤PD-TD≤1.50g/cm ³ Or 0.40g/cm ³ ≤PD-TD≤1.35g/cm ³ . For example, the number of the cells to be processed, PD-TD is 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.02, 0.1.1.02, 1.1.1.0.0.74, 1.9, 0.96, 0.86, 0.80, 0.87, 0.80, 0.81, 0.90. 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, 1.31, 1.32, 1.33, 1.34, 1.35, 1.36, 1.37, 1.38, 1.39, 1.40, 1.41, 1.42, 1.43, 1.44, 1.45, 1.46, 1.47, 1.48, 1.49, 1.50, 1.51, 1.52, 1.53, 1.54, 1.55, 1.56, 1.57, 1.58, 1.59, 1.60, 1.61, 1.62, 1.64, 1.65, 1.66, 1.65, 1.70, 1.60, 1.66, 1.60 and 1.66 ³ Or any two thereof.

In some embodiments, the layered oxide cathode material has a 003 interplanar spacing of 5.25-5.35 a. For example, the 003 interplanar spacing is within a range defined by 5.25, 5.26, 5.27, 5.28, 5.29, 5.30, 5.31, 5.32, 5.33, 5.34, 5.35 a, or any two thereof.

In some embodiments, the layered oxide positive electrode material has a formula a+b+c in the range of 0.70 to 1.00. For example, a+b+c is within a range defined by 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, or any two thereof.

In some embodiments, the ratio of d/(a+b+c) in the general formula of the layered oxide cathode material is 0 to 0.35, for example 0 to 0.25. For example, d/(a+b+c) is within a range defined by 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, or any two thereof.

In some embodiments, the layered oxide cathode material has a pH of 10.50 to 13.00, preferably 11.50 to 13.00. For example, the pH is within a range defined by 10.50, 10.60, 10.70, 10.80, 10.90, 11.00, 11.10, 11.20, 11.30, 11.40, 11.50, 11.60, 11.70, 11.80, 11.90, 12.00, 12.10, 12.20, 12.30, 12.40, 12.50, 12.60, 12.70, 12.80, 12.90, 13.00, or any two thereof.

In some embodiments, the layered oxide cathode material has a residual Na content of 10000 ppm or less. For example, the residual Na content is 10000, 9500, 9000, 8500, 8000, 7500, 7000, 6500, 6000, 5500, 5000, 4500, 4000, 3500, 3000, 2500, 2000, 1500, 1000, or 500ppm.

In the general formula of the layered oxide cathode material of the present invention, the subscript x of Na element satisfies: x is more than or equal to 0.90 and less than or equal to 1.10. For example, x is within a range defined by 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, or any two thereof; the subscript a of Cu element satisfies: a is more than or equal to 0.10 and less than or equal to 0.40. For example, a is within a range defined by 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, or any two thereof; the subscript b of the Mn element satisfies: b is more than or equal to 0.20 and less than or equal to 0.80. For example, b is within any of the ranges defined for 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.80, or both; the subscript c of the Fe element satisfies: c is more than or equal to 0.20 and less than or equal to 0.40. For example, c is within a range defined by 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, or any two thereof; the subscript d of doping element M satisfies: d is more than or equal to 0 and less than or equal to 0.50. For example, d is within a range defined by 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, or any two of them; the subscript e of the oxygen element satisfies: e is more than or equal to 1.70 and less than or equal to 2.40. For example, e is any of ranges 1.70, 1.71, 1.72, 1.73, 1.74, 1.75, 1.76, 1.77, 1.78, 1.79, 1.80, 1.81, 1.82, 1.83, 1.84, 1.85, 1.86, 1.87, 1.88, 1.89, 1.90, 1.91, 1.92, 1.93, 1.94, 1.95, 1.96, 1.97, 1.98, 1.99, 2.00, 2.01, 2.02, 2.03, 2.04, 2.05, 2.06, 2.07, 2.08, 2.09, 2.10, 2.11, 2.12, 2.13, 2.14, 2.15, 2.16, 2.17, 2.18, 2.19, 2.20, 2.21, 2.22, 2.203, 2.24, 2.25, 2.26, 2.27, 2.29, 2.34, 2.33, 2.36, 2.32, 2.38, 2.34, 2.36, 2.32, or both.

In the layered oxide cathode material of the present invention, the total doping amount of the doping element M selected from one or more of Mg, al, si, ti, cr, co, ni, zn, Y, zr, sb, la, ce, W, F, expressed by the subscript d, is 0 to 0.50 or is any value or any subrange within the range of 0 to 0.50 as mentioned above. In the layered oxide cathode material of the present invention, the doping element M may be doped alone or in combination of a plurality of elements. When doped alone, the doping amount of the element doped alone is in the range of more than 0 to equal to or less than 0.50; when a plurality of elements are doped in combination, the total doping amount of the doping elements is in the range of more than 0 to less than or equal to 0.50.

In some embodiments, preferably, when the Ni element is doped alone, the doping amount of the Ni element may be greater than 0 to equal to or less than 0.35, for example, within a range defined by 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, or any two thereof. Preferably, when Mg element is doped alone, the doping amount of Mg element may be in a range of greater than 0 to equal to or less than 0.30, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, or any two thereof; preferably, when the Zr element is doped alone, the doping amount of the Zr element may be in a range of greater than 0 to equal to or less than 0.20, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, or any two thereof; preferably, when the Al element is doped alone, the doping amount of the Al element may be in a range of greater than 0 to equal to or less than 0.30, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, or any two thereof; preferably, when the Zn element is doped alone, the doping amount of the Zn element may be in a range of greater than 0 to equal to or less than 0.30, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, or any two thereof; preferably, when the Y element is doped alone, the doping amount of the Y element may be in a range of greater than 0 to equal to or less than 0.30, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, or any two thereof; preferably, when the Ti element is doped alone, the doping amount of the Ti element may be in a range defined by more than 0 to 0.15, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, or any two thereof; preferably, when the La element is doped alone, the doping amount of the La element may be in a range defined by more than 0 to 0.15, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, or any two thereof; preferably, when the F element is doped alone, the doping amount of the F element may be in a range defined by greater than 0 to equal to or less than 0.20, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, or any two thereof.

Those skilled in the art will appreciate that the doping element M may also be doped with a combination of elements. Preferably, in the case of the combination doping, the respective doping amounts of the elements of the combination doping may be within the above-described preferred ranges when the respective doping elements are doped alone, and the total doping amount of the respective elements of the combination doping is from more than 0 to less than or equal to 0.50 or any value or any subrange within the range of 0 to 0.50 as mentioned above. As an example, when the Ni element and the other element are doped in combination, the doping amount of the Ni element may be in the above-described range of 0 to 0.35 inclusive, and the total doping amount of the Ni element and the other element may be in the above-described range of 0 to 0.50 inclusive; when Mg element and other elements are doped in combination, the doping amount of Mg element may be in the above-described range of 0 to 0.30 inclusive, and the total doping amount of Mg element and other elements may be in the above-described range of 0 to 0.50 inclusive; when the Zr element and the other element are doped in combination, the doping amount of the Zr element may be in the above-described range of 0 to 0.20 inclusive, and the total doping amount of the Zr element and the other element may be in the above-described range of 0 to 0.50 inclusive; when the Al element and the other element are doped in combination, the doping amount of the Al element may be in the above-described range of 0 to 0.30 inclusive, and the total doping amount of the Al element and the other element may be in the above-described range of 0 to 0.50 inclusive; when the Zn element and the other element are doped in combination, the doping amount of the Zn element may be in the above-described range of 0 to 0.30 inclusive, and the total doping amount of the Zn element and the other element may be in the above-described range of 0 to 0.50 inclusive; when the Ti element and other elements are doped in combination, the doping amount of the Ti element may be in the above-described range of 0 to 0.15 inclusive, and the total doping amount of the Ti element and other elements may be in the above-described range of 0 to 0.50 inclusive; when the La element and the other elements are doped in combination, the doping amount of the La element may be in the above-described range of 0 to 0.15 inclusive, and the total doping amount of the La element and the other elements may be in the above-described range of 0 to 0.50 inclusive; when the F element and the other elements are doped in combination, the doping amount of the F element may be in the above-described range of 0 to 0.20 inclusive, and the total doping amount of the F element and the other elements may be in the above-described range of 0 to 0.50 inclusive.

In some embodiments, preferably, when the Mg element and the Zr element are doped in combination, the doping amount of the Mg element may be in a range of greater than 0 to equal to or less than 0.30, such as 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, or any two of them, and the doping amount of the Zr element may be in a range of greater than 0 to equal to or less than 0.20, such as 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.16, 0.20, 0.15, or any two of them; when the Y element and the F element are doped in combination, the doping amount of the Y element may be in a range of greater than 0 to equal to or less than 0.30, such as 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, or any two of them, and the doping amount of the F element may be in a range of greater than 0 to equal to or less than 0.20, such as 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.14, 0.16, 0.17, 0.16, 0.20, or any two of them; when Ni element and Ti element are doped in combination, the doping amount of Ni element may be in a range of greater than 0 to equal to or less than 0.35, such as defined by 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, or any two thereof, and the doping amount of Ti element may be in a range of greater than 0 to equal to or less than 0.15, such as defined by 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.15, or any two of them; when the Ni element and the La element are doped in combination, the doping amount of the Ni element may be in a range of greater than 0 to equal to or less than 0.35, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, or any two of them, and the doping amount of the La element may be in a range of greater than 0 to equal to or less than 0.15, for example, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.15, or any two of them.

It has been found that when the content relationship of each element in the general formula of the layered oxide cathode material of the present invention satisfies one or more of the following conditions, one or more of the air stability, initial efficiency, rate discharge performance, or cycle performance of the obtained layered oxide cathode material can be further improved.

In some embodiments, the layered oxide positive electrode material has a ratio of x to a of from 2.50 to 10.00, such as from 4.00 to 8.50. For example, the ratio of x to a is within a range defined by 2.50, 3.00, 3.50, 4.00, 4.50, 5.00, 5.50, 6.00, 6.50, 7.00, 7.50, 8.00, 8.50, 9.00, 9.50, 10.00, or any two thereof.

In some embodiments, the layered oxide positive electrode material has a ratio of a to b in the general formula of 0.10 to 1.80, for example 0.35 to 0.75. For example, the ratio of a to b is within a range defined by 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, or any two thereof.

In some embodiments, the ratio of c to b in the general formula of the layered oxide cathode material is from 0.25 to 1.50, such as from 0.25 to 1.00. For example, the ratio of c to b is within a range defined by 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, or any two thereof.

Preparation method of layered oxide cathode material

A second aspect of the present invention provides a method of preparing a layered oxide cathode material according to the first aspect of the present invention, comprising the steps of:

step b: sintering the precursor obtained in the step a; and

The respective steps will be specifically described below.

Step a

In step a, a Na source, a Cu source, a Mn source, a Fe source, and optionally an M source are uniformly mixed in stoichiometric proportions to obtain a mixture precursor.

In some embodiments, the Na source, cu source, mn source, fe source, optionally M source may be any Na, cu, mn, fe, or M-containing compound known to those skilled in the art for use in preparing positive electrode materials for sodium ion secondary batteries. Preferably, the Na source, cu source, mn source, fe source, and M source as metal are respectively selected from one or more of carbonate, bicarbonate, nitrate, acetate, oxalate, hydroxide, and oxide of the corresponding element. As an example, the sodium source may be in the form of one or more of a sodium-containing oxide, hydroxide, salt, or the like. In one or more embodiments, the Na source may be one or more of the compounds selected from the group consisting of: sodium carbonate, sodium bicarbonate, sodium nitrate, sodium acetate, sodium oxalate, sodium hydroxide and sodium oxide; the Cu source may be one or more selected from the group consisting of: copper carbonate, copper nitrate, copper acetate, copper oxalate, copper hydroxide and copper oxide; the Mn source may be one or more selected from the group consisting of: manganese carbonate, manganese nitrate, manganese acetate, manganese oxalate, manganese hydroxide, and manganese oxide (e.g., manganese dioxide); the Fe source may be one or more selected from the group consisting of: iron carbonate, iron nitrate, iron acetate, iron oxalate, iron hydroxide and iron oxide. Alternatively or additionally, some or all of the Cu source, fe source, mn source, and optionally M source as metal may also be a composite oxide or composite hydroxide.

In the layered oxide cathode material of the present invention, the M source is optionally present, wherein M is selected from one or more of Mg, al, si, ti, cr, co, ni, zn, Y, zr, sb, la, ce, W, F, preferably one or more of Mg, al, ti, zn, Y, zr, F, more preferably one or more of Mg, al, ti, zr, F. The M source may be any element M-containing compound known to those skilled in the art for preparing a positive electrode material of a sodium ion secondary battery. For example, the M source as the metal may be selected from one or more of carbonates, bicarbonates, nitrates, acetates, oxalates, hydroxides, and oxides of the corresponding elements. For example, when a Mg source is used, the Mg source may be one or more selected from the group consisting of: magnesium carbonate, magnesium nitrate, magnesium acetate, magnesium oxalate, magnesium hydroxide and magnesium oxide; when an Al source is used, the Al source may be one or more selected from the group consisting of: aluminum carbonate, aluminum nitrate, aluminum acetate, aluminum oxalate, aluminum hydroxide, and aluminum oxide; when a Ti source is used, the Ti source may be one or more selected from the group consisting of: titanium carbonate, titanium nitrate, titanium acetate, titanium oxalate, titanium hydroxide and titanium oxide; when a Zn source is used, the Zn source may be one or more selected from the group consisting of: zinc carbonate, zinc nitrate, zinc acetate, zinc oxalate, zinc hydroxide, and zinc oxide; when a Y source is used, the Y source may be one or more compounds selected from the group consisting of: yttrium carbonate, yttrium nitrate, yttrium acetate, yttrium oxalate, yttrium hydroxide and yttrium oxide; when a Zr source is used, the Zr source may be one or more selected from the group consisting of: zirconium carbonate, zirconium nitrate, zirconium acetate, zirconium oxalate, zirconium hydroxide, and zirconium oxide; when a Ni source is used, the Ni source may be one or more selected from the group consisting of: nickel carbonate, nickel nitrate, nickel acetate, nickel oxalate, nickel hydroxide and nickel oxide; when a La source is used, the La source may be one or more selected from the group consisting of: lanthanum carbonate, lanthanum bicarbonate, lanthanum nitrate, lanthanum acetate, lanthanum oxalate, lanthanum hydroxide, and lanthanum oxide. Alternatively or additionally, some or all of the Mg source, al source, ti source, zn source, Y source, zr source, ni source, la source may also be a composite oxide or composite hydroxide. When M comprises F, the F source may be selected from one or both of ammonium fluoride, sodium fluoride. When M comprises Si, the Si source may be selected from one or more of silicic acid, silicate esters, and silicon oxide.

The mixing may be performed in any suitable mixing manner known to those skilled in the art. In one or more embodiments, the mixing in step a is performed by a solid phase mixing method or a liquid phase mixing method. In some embodiments, where solid phase mixing is used, the slurry (solids content, e.g., 30-45 wt.%) is milled to a particle size of 150-800nm, e.g., 300-500nm, by a milling medium, such as zirconium spheres.

Step b

In step b, the precursor obtained in step a is sintered.

The sintering may be performed under an oxidizing atmosphere. Preferably, the oxidizing atmosphere is compressed air or oxygen. The pressure of the compressed air may be any commonly used pressure, for example, 0.1MPa or more, for example, 0.1 to 0.5MPa. The pressure of the oxidizing atmosphere is 0.15Mpa or more, for example, 0.15 to 0.5Mpa. The oxidizing atmosphere may be flowing, for example at a flow rate of 5-20L/(min-kg), where kg refers to the mass of the sintered mixture on a dry weight basis.

The sintering temperature may be 750-1200 ℃, preferably 800-1100 ℃. In one or more embodiments, the sintering temperature can be, for example, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, 1200 ℃, or any two thereof.

The sintering time is not particularly limited and may be 10 to 48 hours, preferably 12 to 36 hours. In one or more embodiments, the sintering time can be, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48 hours, or within a range defined by any two of them.

The temperature rising rate at the time of sintering is not particularly limited, and may be 1 to 10 ℃/min, preferably 2 to 5 ℃/min, and may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ℃/min, or a range defined by any two thereof.

In some embodiments, the step b comprises a first sintering process, a second sintering process, and optionally a third sintering process, which are performed sequentially, wherein

The sintering temperature T1 of the first sintering process, the sintering temperature T2 of the second sintering process, and the sintering temperature T3 of the third sintering process satisfy: t1< T2< T3;

the sintering time t1 of the first sintering process, the sintering time t2 of the second sintering process, and the sintering time t3 of the third sintering process satisfy: t1 is less than or equal to t2 and less than or equal to t3.

Preferably, as described above, the sintering step in the preparation process of the layered oxide cathode material of the present invention is a stepwise sintering, which allows the layered structure to grow from the outside to the inside by controlling the crystal growth, thereby compacting the inside of the particles without voids. Step sintering does not need to increase the sintering temperature to indirectly increase the crystal growth speed, and does not need to supplement excessive sodium content to compensate the volatilization of sodium salt caused by the increase of the temperature. Step sintering is carried out by maintaining the sintering temperature at the material phase formation temperature, and further gradually diffusing the molten sodium salt from outside to inside to the transition metal compound, accompanied by the formation of a layered structure. In addition, step sintering can balance unstable factors such as material phase formation, crystal growth and the like in the sintering process, such as sintering atmosphere, radiant heat intensity and the like, so that the process stability of the material particle growth process is ensured.

Preferably, the sintering temperature T1 of the first sintering process satisfies: t1 is more than or equal to 750 ℃ and less than or equal to 850 ℃, and sintering time T1 is 2-10h; and/or

The sintering temperature T2 of the second sintering process satisfies: t2 is more than or equal to 850 ℃ and less than or equal to 1000 ℃, and the sintering time T2 is 4-20h; and/or

The sintering temperature T3 of the third sintering process satisfies: t3 is more than or equal to 900 ℃ and less than or equal to 1200 ℃, and sintering time T3 is 6-20h.

In some embodiments, the sintering temperature T1 of the first sintering process is 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850 ℃, or any two thereof, and the sintering time T1 is 2, 3, 4, 5, 6, 7, 8, 9, 10h, or any two thereof.

In some embodiments, the second sintering process has a sintering temperature T2 within a range defined by 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000 ℃, or any two thereof, and a sintering time T2 within a range defined by 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20h, or any two thereof.

In some embodiments, the third sintering process has a sintering temperature T3 of 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1010, 1020, 1030, 1040, 1050, 1060, 1070, 1080, 1090, 1100, 1110, 1120, 1130, 1140, 1150, 1160, 1170, 1180, 1190, 1200 ℃, or any two thereof, and a sintering time T3 of 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20h, or any two thereof.

In some embodiments, cooling, optionally crushing, sieving, is also included between the first sintering process and the second sintering process, and between the second sintering process and the third sintering process.

Step c

In step c, the product obtained in step b is cooled, optionally crushed, sieved.

The cooling, comminution and sieving in steps b and c can be carried out by any suitable means known to the person skilled in the art. For example, the cooling may be natural cooling, air cooling, or water cooling. For example, the comminution may be jet milling or mechanical milling.

Positive electrode composition

A third aspect of the present invention provides a positive electrode composition for a sodium ion secondary battery, which comprises the layered oxide positive electrode material according to the first aspect of the present invention.

The positive electrode composition (for a sodium ion secondary battery) may further include a conductive agent, a binder, and any other substances that can be used by those skilled in the art as needed, such as a dispersant and an additive for improving stability, etc., in addition to the layered oxide positive electrode material of the present invention.

In some embodiments, the layered oxide cathode material may be present in an amount commonly used in the art, for example, from 70 to 95 wt%, such as from 80 to 90 wt%, based on the dry weight of the (sodium ion secondary battery) cathode composition.

The kind of the conductive agent is not particularly limited as long as it has the property of enhancing the conductivity of the positive electrode and does not adversely affect the properties of the positive electrode material. The person skilled in the art can select the conductive agent commonly used in the art according to actual needs. As an example, the conductive agent for the (sodium ion secondary battery) cathode composition may be selected from one or more of superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

In some embodiments, the conductive agent may be present in an amount commonly used in the art, such as 1 to 10 wt%, for example 2 to 5 wt%, based on the dry weight of the positive electrode composition (for a sodium ion secondary battery).

The binder is not particularly limited as long as it has the function of enhancing the adhesion between the positive electrode active material particles and the adhesion with the current collector and does not adversely affect the performance of the positive electrode material. Those skilled in the art can make the selection according to actual needs. As an example, the binder used for the (sodium ion secondary battery) cathode composition may be selected from one or more of a polyfluoroolefin-based binder such as polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA) or modified (e.g., carboxylic acid, acrylic acid, acrylonitrile, etc. modified) derivatives thereof, and styrene-butadiene rubber, acrylic resin, carboxymethyl cellulose, polyvinyl alcohol (PVA), etc.

In some embodiments, the binder is present in an amount of 1 to 10 wt%, such as 2 to 5 wt%, based on the dry weight of the positive electrode composition (for a sodium ion secondary battery).

The positive electrode composition may be in the form of a slurry, i.e., it may further include a solvent. The positive electrode composition may also be in a dry form, i.e., it does not include a solvent, for example, it may be in the form of a positive electrode active material layer disposed on a positive electrode current collector.

Sodium ion secondary battery

A fourth aspect of the present invention provides a sodium-ion secondary battery. The sodium ion secondary battery generally includes a positive electrode, a negative electrode, a separator, and an electrolyte.

In some embodiments, the sodium ion secondary battery may further include an exterior package for packaging the electrode assembly and the electrolyte. For example, the overwrap may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc., or a soft package, such as a pouch-type soft package, such as a soft package made of polypropylene (PP), polybutylene terephthalate (PBT), polybutylene succinate (PBS), etc.

The shape of the sodium ion secondary battery is not particularly limited, and may be a cylindrical shape, a square shape, or any other shape.

The sodium ion secondary battery may be manufactured by a method generally used in the art, for example, the positive electrode tab, the negative electrode tab, and the separator may be manufactured into a battery cell through a winding process or a lamination process, and then an electrolyte is injected.

Positive electrode

The positive electrode (or positive electrode tab) includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector, the positive electrode active material layer including the positive electrode active material composition of the third aspect of the present invention, for example, in a dried form. The positive electrode also forms an aspect of the present invention.

The positive electrode current collector is not particularly limited, and a positive electrode current collector commonly used by those skilled in the art may be employed. As an example, the positive electrode current collector may employ a metal foil such as an aluminum foil, a nickel foil, or a composite current collector. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), 1, 3-Propane Sultone (PS), polyethylene (PE), etc.), but the present invention is not limited to these materials.

The positive electrode sheet may be prepared according to a method generally employed in the art.

For example, the positive electrode may be formed by: uniformly dispersing a positive electrode active material, a conductive agent and a binder in a solvent (such as N-methylpyrrolidone (NMP)) to obtain a positive electrode slurry; and coating the slurry on a positive electrode current collector, drying and pressing.

Alternatively, the positive electrode may be formed by: uniformly dispersing a positive electrode active material, a conductive agent and a binder in a solvent (such as N-methylpyrrolidone (NMP)) to obtain a positive electrode slurry; the positive electrode slurry was cast on a separate support, dried, and the resulting positive electrode film was separated from the support and laminated on a positive electrode current collector.

Negative electrode

The negative electrode (or negative electrode tab) may be a metal sodium tab, or may include a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, where the negative electrode active material layer includes a negative electrode active material.

The negative electrode current collector is not particularly limited, and a negative electrode current collector commonly used by those skilled in the art may be employed. As an example, the negative electrode current collector may be a metal foil such as copper foil, or a composite current collector. The composite current collector may include a polymeric material base layer and a metal layer formed on at least one surface of the polymeric material base layer. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel alloy, titanium alloy, silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.), but the present invention is not limited to these materials.

In some embodiments, the anode active material may employ an active material commonly used by those skilled in the art. For example, the negative active material may be one or more of natural graphite, artificial graphite, mesophase micro carbon spheres (MCMB), hard carbon, soft carbon, silicon-based material, tin-based material, lithium titanate, and metallic sodium. The silicon-based material can be one or more of elemental silicon, a silicon oxygen compound, a silicon carbon compound and a silicon alloy, and the tin-based material can be one or more of elemental tin, a tin oxygen compound and a tin alloy.

In addition to the anode active material, a binder, a conductive agent, and any other optional auxiliary agents such as a thickener, etc. may be included in the anode active material layer.

The negative electrode conductive agent is not particularly required, and may be selected from one or more of graphite, superconducting carbon, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers, as an example.

In some embodiments, the conductive agent may be contained in an amount of 1 to 10 wt%, for example, 2 to 5 wt%, based on the total weight (dry weight) of the anode active material layer.

The negative electrode binder is not particularly required, and is exemplified by one or more selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl butyral (PVB), styrene-butadiene rubber (SBR), aqueous acrylic resin, and carboxymethyl cellulose (CMC).

In some embodiments, the binder may be contained in an amount of 1 to 10 wt%, for example, 2 to 5 wt%, based on the total weight (dry weight) of the anode active material layer.

The negative electrode may be prepared according to a method generally employed in the art.

For example, the negative electrode may be formed by: uniformly dispersing a negative electrode active material and optionally a conductive agent, a binder, and a thickener in a solvent such as N-methylpyrrolidone (NMP) or deionized water to form a negative electrode slurry; and coating the negative electrode slurry on a negative electrode current collector, drying and pressing.

Alternatively, the anode may be formed by: uniformly dispersing a negative electrode active material and optionally a conductive agent, a binder, and a thickener in a solvent such as N-methylpyrrolidone (NMP) or deionized water to form a negative electrode slurry; the negative electrode slurry was cast on a separate support, dried, and the resulting negative electrode film was separated from the support and laminated on a negative electrode current collector.

Electrolyte composition

The electrolyte plays a role in ion conduction between the positive electrode plate and the negative electrode plate. The electrolyte is not particularly limited and may be selected according to the requirements. For example, the electrolyte may be selected from at least one of a solid electrolyte, a gel electrolyte, and a liquid electrolyte (i.e., an electrolyte solution).

In some embodiments, the electrolyte is an electrolyte. The electrolyte comprises an organic aprotic solvent and an electrolyte sodium salt.

In some embodiments, the solvent may be selected from one or more of Ethylene Carbonate (EC), propylene Carbonate (PC), ethylmethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), butylene Carbonate (BC), fluoroethylene carbonate (FEC), methyl Formate (MF), methyl Acetate (MA), ethyl Acetate (EA), propyl Acetate (PA), methyl Propionate (MP), ethyl Propionate (EP), propyl Propionate (PP), methyl Butyrate (MB), ethyl Butyrate (EB), 1, 4-butyrolactone (GBL), sulfolane (SF), dimethylsulfone (MSM), methylsulfone (EMS), and diethylsulfone (ESE).

In some embodiments, the electrolyte sodium salt may be selected from sodium hexafluorophosphate (NaPF) ₆ ) Sodium tetrafluoroborate (NaBF) ₄ ) Sodium perchlorate (NaClO) ₄ ) Sodium hexafluoroborate (NaBF) ₆ ) Sodium bis (fluorosulfonyl) imide (NaFSI), sodium bis (trifluoromethylsulfonyl) imide (NaTFSI), sodium (NaTFS) triflate, sodium (NaDFOB) difluorooxalato borate, sodium (NaBOB) dioxaoxalato borate, sodium (NaPO) ₂ F ₂ ) One or more of sodium difluorooxalato phosphate (NaDFOP) and sodium tetrafluorooxalato phosphate (NaDFOP).

In some embodiments, the concentration of sodium ions in the electrolyte is 0.2 to 2 mol/L, for example 0.5 to 1.0 mol/L.

In some embodiments, additives are optionally also included in the electrolyte. As an example, the additive may include an additive that contributes to film formation of a negative electrode or to film formation of a positive electrode, and may further include an additive that can improve battery performance, such as an additive that improves high-temperature or low-temperature performance of a battery, or the like.

Diaphragm

The separator is not particularly limited, and a commonly used porous structure separator having electrochemical stability and chemical stability may be used, for example, it may be a single-layer or multi-layer film of one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. When a solid electrolyte is used, the separator may also be omitted.

Use of the same

A fifth aspect of the invention provides the use of a sodium ion secondary battery according to the fourth aspect of the invention in an energy storage device for solar power generation, wind power generation, smart grid peaking, distribution power stations, backup power sources or communication base stations.

Those skilled in the art will appreciate that the sodium ion secondary battery of the fourth aspect of the present invention may be used for other applications as well. For example, the sodium ion secondary battery may be used as a power source or energy storage unit in mobile devices (e.g., cell phones, etc.), electric vehicles (e.g., electric-only vehicles, hybrid electric vehicles, electric bicycles, electric scooters, etc.), electric trains, and the like.

Examples

The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.

1. Preparation example

Example 1

(1) Respectively weighing Cu according to stoichiometric ratio _1/3 Fe _1/3 Mn _1/3 (OH) ₂ And Na (Na) ₂ CO ₃ Uniformly mixing to obtain a mixture precursor;

(2) Sintering the precursor obtained in the step (1) in an atmosphere furnace for one time by the following steps: introducing dry compressed air (0.3 Mpa), sintering at 750 ℃ for 4 hours;

(3) The primary sintered product was cooled, followed by mechanical pulverization (feed frequency 20Hz, pulverization frequency 35Hz, classification frequency 35Hz, induced air frequency 35Hz, the same applies below), and then secondary sintering was performed in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 850 ℃ for 6h;

(4) The twice sintered product was cooled, followed by mechanical crushing (as above), and then three times sintered in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 900 ℃ for 8 hours; and

(5) Cooling the product of the third sintering, and then mechanically crushing and sieving to obtain NaCu _0.33 Mn _0.33 Fe _0.33 O _2.00 (i.e. NaCu) _1/3 Mn _1/3 Fe _1/3 O _2.00 ) Is a layered oxide positive electrode material. As can be seen from fig. 1, the layered oxide cathode material prepared in example 1 has a spherical shape.

Example 2

(1) Respectively weighing Na according to stoichiometric ratio ₂ CO ₃ 、CuO、MnO ₂ And Fe (Fe) ₂ O ₃ . Adding them into ball milling tank, using pure water as dispersion liquid, zirconium balls as grinding medium, grinding by omnibearing planetary ball mill to obtain D _v Mixed slurry 50-300 nm (test methods see below);

(2) Drying the mixed slurry by spray drying until the water content is less than or equal to 2% (mass fraction, the same applies below) to obtain a precursor;

(3) The precursor obtained was sintered once in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 800 ℃ for 2h;

(4) The primary sintered product was cooled, followed by jet milling (feed frequency 10Hz, jet pressure 0.5MPa, classification frequency 80Hz, induced air frequency 50Hz, the same applies below), and then secondary sintering was carried out in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 880 ℃ for 4h;

(5) The secondary sintered product was cooled, followed by jet milling (as above), and then three-times sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 920 ℃ for 10h;

(6) Cooling the product of the third sintering, and then carrying out jet milling and sieving to obtain a product with a general formula of Na _1.08 Cu _0.11 Mn _0.67 Fe _0.22 O _2.32 Is a layered oxide positive electrode material.

Example 3

(1) Respectively weighing (Cu) _3/8 Mn _2/8 Fe _3/8 )(OH) ₂ And Na (Na) ₂ CO ₃ Uniformly mixing to obtain a mixture precursor;

(2) Sintering the precursor obtained in the step (1) in an atmosphere furnace for one time by the following steps: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 850 ℃ for 6h;

(3) The primary sintered product was cooled, followed by jet milling (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 920 ℃ for 8h;

(4) The secondary sintered product was cooled, followed by jet milling (as above), and then three-times sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 950 ℃ for 6h; and

(5) Cooling the product of the third sintering, and then carrying out jet milling and sieving to obtain a product with a general formula of Na _0.92 Cu _0.375 Mn _0.25 Fe _0.375 O _1.90 Is a layered oxide positive electrode material. As can be seen from fig. 2, the layered oxide cathode material prepared in example 3 has a spherical shape.

Example 4

(1) Respectively weighing Na according to stoichiometric ratio ₂ CO ₃ 、CuO、MnO ₂ 、Fe ₂ O ₃ MgO and ZrO ₂ . Adding them into ball milling tank, using pure water as dispersion liquid, zirconium balls as grinding medium, grinding by omnibearing planetary ball mill to obtain D _v 50-400 nm mixed slurry;

(2) Drying the mixed slurry by spray drying until the water content is less than 2%, so as to obtain a precursor;

(3) The precursor obtained was sintered once in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 800 ℃ for 8 hours;

(4) The primary sintered product was cooled, followed by mechanical crushing (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 950 ℃ for 10h;

(5) The twice sintered product was cooled, followed by mechanical crushing (as above), and then three times sintered in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 990 ℃ for 15h; and

(6) Cooling the product of the third sintering, and then mechanically crushing and sieving to obtain a compound of the general formula Na _0.95 Cu _0.11 Mn _0.60 Fe _0.22 Mg _0.05 Zr _0.02 O _2.21 Is a layered oxide positive electrode material.

Example 5

(1) Respectively weighing (Cu) _0.12 Mn _0.34 Fe _0.36 Al _0.18 )(OH) _2.18 And Na (Na) ₂ CO ₃ Uniformly mixing to obtain a mixture precursor;

(2) Sintering the precursor obtained in the step (1) in an atmosphere furnace for one time by the following steps: introducing dry compressed air (0.3 Mpa), sintering at 820 ℃ for 6h;

(3) The primary sintered product was cooled, followed by mechanical crushing (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 980 ℃ for 12h; and

(4) Cooling the secondary sintered product, and then mechanically pulverizing and sieving to obtain NaCu _0.12 Mn _0.34 Fe _0.36 Al _0.18 O _2.11 Is a layered oxide positive electrode material.

Example 6

(1) Respectively weighing Na according to stoichiometric ratio ₂ CO ₃ 、CuO、MnO ₂ 、Fe ₂ O ₃ And ZnO. Adding them into ball milling tank, using pure water as dispersion liquid, zirconium balls as grinding medium, grinding by omnibearing planetary ball mill to obtain D _v Mixed slurry of 50-450 nm;

(3) The precursor obtained was sintered once in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 810 ℃ for 7h;

(4) The primary sintered product was cooled, followed by jet milling (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 880 ℃ for 5h;

(5) The secondary sintered product was cooled, followed by jet milling (as above), and then three-times sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 1030 ℃ for 12h; and

(6) Cooling the product of the third sintering, and then carrying out jet milling and sieving to obtain a product with a general formula of Na _1.08 Cu _0.25 Mn _0.35 Fe _0.25 Zn _0.15 O _2.02 Is a layered oxide positive electrode material.

Example 7

(1) Respectively weighing Na according to stoichiometric ratio ₂ CO ₃ 、CuO、MnO ₂ 、Fe ₂ O ₃ 、Y ₂ O ₃ And NaF. Adding them into ball milling tank, using pure water as dispersion liquid and zirconium balls as grinding medium, grinding by omnibearing planetary ball mill to obtain D _v 50-300 nm mixed slurry;

(3) The precursor obtained was sintered once in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 780 ℃ for 9h;

(4) The primary sintered product was cooled, followed by mechanical crushing (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 900 ℃ for 8h;

(5) The twice sintered product was cooled, followed by mechanical crushing (as above), and then three times sintered in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 1050 ℃ for 8h; and

(6) Cooling the product of the third sintering, and then mechanically crushing and sieving to obtain a compound of the general formula Na _0.98 Cu _0.15 Mn _0.35 Fe _0.25 Y _0.10 F _0.05 O _1.84 Is a layered oxide positive electrode material.

Example 8

(1) Respectively weighing (Cu) _0.12 Mn _0.32 Fe _0.32 Ni _0.20 Ti _0.04 )(OH) ₂ And Na (Na) ₂ CO ₃ Uniformly mixing to obtain a mixture precursor;

(2) Sintering the precursor obtained in the step (1) in an atmosphere furnace for one time by the following steps: introducing dry compressed air (0.3 Mpa), sintering at 760 ℃ for 10 hours;

(3) The primary sintered product was cooled, followed by jet milling (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 950 ℃ for 15h; and

(4) Cooling the secondary sintered product, and then carrying out jet milling and sieving to obtain a product with a general formula of Na _1.02 Cu _0.12 Mn _0.32 Fe _0.32 Ni _0.20 Ti _0.04 O _2.03 Is a layered oxide positive electrode material.

Example 9

(1) Respectively weighing Na according to stoichiometric ratio ₂ CO ₃ 、CuO、MnO ₂ 、Fe ₂ O ₃ NiO and La ₂ O ₃ . Adding them into ball milling tank, using pure water as dispersion liquid, zirconium balls as grinding medium, grinding by omnibearing planetary ball mill to obtain D _v 50-500 nm mixed slurry;

(3) The precursor obtained was sintered once in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 800 ℃ for 4 hours;

(4) The primary sintered product was cooled, followed by mechanical crushing (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 990 ℃ for 18h; and

(5) Cooling the secondary sintered product, and mechanically pulverizing and sieving to obtain a product with a general formula of Na _1.02 Cu _0.20 Mn _0.50 Fe _0.25 Ni _0.20 La _0.03 O _2.33 Is a layered oxide positive electrode material.

Comparative example 1

(1) Respectively weighing (Cu) _1/3 Mn _1/3 Fe _1/3 )(OH) ₂ And Na (Na) ₂ CO ₃ Uniformly mixing to obtain a mixture precursor;

(3) The primary sintered product was cooled, followed by mechanical crushing (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing dry compressed air (0.3 Mpa), sintering at 850 ℃ for 6h;

(5) Cooling the product of the third sintering, and then mechanically crushing and sieving to obtain NaCu _0.33 Mn _0.33 Fe _0.33 O ₂ (i.e. NaCu) _1/3 Mn _1/3 Fe _1/3 O ₂ ) Is a layered oxide positive electrode material.

Comparative example 2

(1) Respectively weighing Na according to stoichiometric ratio ₂ CO ₃ 、CuO、MnO ₂ And Fe (Fe) ₂ O ₃ . They were added to a ball millGrinding in a tank with pure water as dispersion liquid and zirconium balls as grinding medium by using an omnibearing planetary ball mill to obtain D _v 50-300 nm mixed slurry;

(4) The primary sintered product was cooled, followed by jet milling (as above), and then secondary sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 880 ℃ for 4h;

(5) The secondary sintered product was cooled, followed by jet milling (as above), and then three-times sintering was performed in an atmosphere furnace by: introducing oxygen (0.25 mpa, 8L/(min.kg)), sintering at 920 ℃ for 10h; and

Comparative example 3

(5) Cooling the product of the third sintering, and then carrying out jet milling and sieving to obtain a product with a general formula of Na _0.92 Cu _0.375 Mn _0.25 Fe _0.375 O _1.90 Is a layered oxide positive electrode material.

Comparative example 4

2. Measurement method

1. D _v 10、D _v 50、D _v 90、D _min And D _max

The test was performed using a malvern 3000 laser particle sizer, lithium cobaltate was selected as the standard substance, water was used as the dispersant, and the following instrument test parameters were set: the test time is 10s, the test times are 3, the shading degree is 6-15%, the stirring speed is 2800r/min, the ultrasonic mode is started, and the power is 50%. And (3) clicking a laser particle sizer (a Markov 3000 laser particle sizer) to start testing, then adding the layered oxide cathode material into a sample cell, and controlling the adding amount to adjust the shading degree of the sample cell to 6-15%. The instrument was automatically repeated 3 times, and the average value of 3 tests was taken as the test result.

2. Sphere degree phi

The test was performed using a particle sphericity analyzer, omega 500 nano. Setting an instrument mode for automatic measurement, and then taking a proper amount of layered oxide positive electrode material according to the layered oxide positive electrode material: distilled water = 1:10, adding a proper amount of positive electrode material into a corresponding amount of distilled water, and stirring to uniformly disperse. And adding the obtained mixture into a feed inlet, clicking a particle sphericity analyzer (Oziaon 500 nano) to start testing, and automatically testing and outputting a result.

3. BET specific surface area

The test was carried out with reference to GB/T19587-2017 determination of specific surface area of solid substance by gas adsorption BET method. The layered oxide cathode material (30-500 mg) was put into a sample tube, and subjected to degassing treatment. After the degassing is finished, the heating power supply is turned off. After the sample cooled to room temperature, helium was backfilled and the sample tube was weighed. The weighed sample tube was loaded into a BET specific surface area analyzer (microscopic Gao Bo JW-DX) and the sample mass was input into an analysis file. The instrument was clicked to begin the adsorption and desorption testing procedure. And automatically outputting a result after the test is finished.

4. Compaction density and tap density

Compaction density:

and weighing 0.5-2 g of layered oxide cathode material and adding the layered oxide cathode material into a die cavity of a die. And placing the die, and adjusting the upper pressure plate and the lower pressure plate to ensure concentricity. And running a compaction density tester (Sansi longitudinal and transverse UTM 7305), and calculating to obtain compaction density results under different pressures through the distances between the upper pressing plate and the lower pressing plate and the bearing pressure. The compaction densities in table 1 were measured at a pressure of 15 kN.

Tap density:

25g of layered oxide cathode material was weighed and put into a standard measuring cylinder (volume 50ml, inner diameter 22 mm), and the measuring cylinder was vibrated by a vibrating machine. The setting parameters of the vibrating machine table are as follows: the stroke is 3mm, the vibration frequency is 100 times/min, and the time is 30min. And (5) reading the volume of the positive electrode material in the measuring cylinder after the vibration, and dividing the powder mass by the volume to obtain the tap density.

5. XRD diffraction

And (5) taking the layered oxide anode material and placing the layered oxide anode material into a carrier. An X-ray diffractometer (Bruce X-ray diffractometer D8 ADVANCE) is arranged at a scanning angle of 10-80 DEG and a scanning speed of 5 DEG/min. And obtaining an XRD spectrum of the layered oxide cathode material. And (3) performing data smoothing, background subtraction, peak searching, phase searching, characteristic peak marking and characteristic peak information reading by using data processing software Jade 6.0. In an embodiment of the present invention, I003/I104 represents the ratio of the peak height of the 003 peak characteristic peak to the peak height of the 104 peak characteristic peak in the XRD spectrum.

6. pH

According to the layered oxide cathode material: distilled water = 1:20, adding a proper amount of positive electrode material into distilled water with corresponding amount, and magnetically stirring at a rotating speed of 600+/-20 r/min for 10min so as to uniformly mix. The resulting mixture was then allowed to stand for 5min, and the pH of the mixture was measured by a pH meter (METTLER TOLEDO pH meter FE 22-Standard) at a constant temperature of 25℃to give the pH of the corresponding material.

7. Residual Na content

According to the layered oxide cathode material: ethanol (analytically pure, density 0.789 g/ml) =1: 20 (mass ratio is marked as b) is added into ethanol with corresponding amount, and the mixture is magnetically stirred for 30min at the rotating speed of 600+/-20 r/min so that the ethanol can drive NaOH and Na on the surface of the material ₂ CO ₃ Fully dissolved. The mixture was then filtered to give a filtrate, and Na in the filtrate was tested using an atomic absorption spectrophotometer (hitachi ZA 3000) ⁺ Content (noted as a, mg/ml), residual Na content of the material was calculated according to the following formula:

residual Na content = (a x (20 x b/0.789))/b=a x 20/0.789 x 1000 mg/kg (i.e. ppm)

8. Scanning Electron Microscope (SEM)

The test was performed using a HITACHI (S-4800) scanning electron microscope with an acceleration voltage of 10kV, a magnification of 10k, and a general topography photographing.

The measurement results of the above physicochemical properties of the layered oxide cathode materials prepared in examples 1 to 9 and comparative examples 1 to 4 are summarized in table 1.

9. Electrochemical performance test

Manufacturing of button cell: the products of examples 1 to 9 and comparative examples 1 to 4 were left at 50% constant humidity for 30min, respectively, and then used as active materials. A glue solution (mass fraction: 10% of N-methylpyrrolidone (NMP), which is a solvent, was uniformly mixed with 0.45g of active material, 0.025g of SP (highly conductive carbon black SUPER P, switzerland) and 0.25. 0.25 g of polyvinylidene difluoride (PVDF, commercially available from SOLVAY PVDF 5130)) and then N-methylpyrrolidone was added thereto to prepare a glue solution having tackiness. Coating the glue solution on aluminum foil (thickness 16 mu m), and baking at 120deg.C for 12 hr in a vacuum drying oven to obtain positive plate (active material surface density 5 mg/cm) ² ). A metallic sodium sheet (Aladin Allatin) was used as a counter electrode (thickness 300.+ -.50 μm). Glass fiber (Waterman) was used as a membrane (thickness 675 μm) and NaPF with a sodium ion concentration of 1mol/L ₆ As an electrolyte, a solution (solvent is a mixture of EC and DMC in a volume ratio of EC/dmc=1:1) (Alfa) was assembled 2032 in an Ar atmosphere protection glove box.

9.1 First charge specific capacity, first discharge specific capacity, and first coulombic efficiency

After 2032 of the button cell is assembled, the button cell is charged to 4.0V at a constant current of 0.1C at the temperature of 25 ℃, then charged to the current of less than or equal to 0.01mA at a constant voltage, and then kept stand for 5 minutes, and the charging specific capacity at the time is recorded as the primary charging specific capacity C0; then, the discharge specific capacity at this time was recorded as the first discharge specific capacity D0 at 0.1C constant current discharge to 2.5V. The first coulombic efficiency is obtained by using the first discharge specific capacity D0/the first charge specific capacity C0×100%.

9.2 discharge at Rate

At a temperature of 25 ℃, charging to 4.0V at a constant current of 0.1C, charging to a current of 0.01mA or less at a constant voltage, then standing for 5 minutes, then discharging to 2.5V at a constant current of 0.1C, and then standing for 5 minutes. The test was cycled 3 times.

Then charging to 4.0V with 1C constant current, charging to current less than or equal to 0.01mA with constant voltage, standing for 5 minutes, discharging to 2.5V with 1C constant current, and standing for 5 minutes. The test was cycled 3 times.

Dividing the average value of the specific discharge capacity circulating for 3 circles at the 1C multiplying power by the average value of the specific discharge capacity circulating for 3 circles at the 0.1C multiplying power, and multiplying by 100%, thus obtaining the multiplying power discharge performance.

9.3 cycle retention

The battery is charged to 4.0V at a constant current of 0.5C and then charged to a current of 0.01mA or less at a constant voltage at 25 ℃, then left for 5 minutes, then discharged to 2.5V at a constant current of 0.5C and then left for 5 minutes, and the discharge specific capacity of the battery is recorded as the discharge specific capacity of the 1 st cycle of the battery. The battery was subjected to 100-cycle charge-discharge test according to the above method, and the discharge specific capacity of the 100 th cycle was recorded. Then the discharge specific capacity of the 100 th cycle/the discharge specific capacity of the 1 st cycle multiplied by 100% is the cycle retention rate.

9.4 Discharging at 25deg.C under 60% humidity for 2 hr

The positive electrode material was divided into two parts, one part was left at 25 ℃ and 60% humidity for 2 hours, then a button cell was produced, and the produced button cell was charged to 4.0V at a constant current of 0.1C, charged at a constant voltage to a current of 0.01mA or less, and left to stand for 5 minutes, and then discharged to 2.5V at a constant current of 0.1C, and left to stand for 5 minutes, and the discharge specific capacity D1 at this time was recorded.

The other part of the positive electrode material is directly manufactured into a button cell without being subjected to the treatment of being placed at 25 ℃ and 60% humidity for 2 hours, and the first discharge specific capacity D0 is measured according to the method described in the 9.1 section, and the discharge specific capacity D1/the first discharge specific capacity D0 multiplied by 100%, namely the discharge performance of the positive electrode material placed at 25 ℃ and 60% humidity for 2 hours is obtained.

The measurement results of the electrochemical properties of the sodium ion secondary batteries prepared from the layered oxide cathode materials prepared in examples 1 to 9 and comparative examples 1 to 4 are summarized in table 2.

Table 1: physicochemical Properties of the materials of examples 1-9 and comparative examples 1-4

Table 2: electrochemical properties of examples 1-9 and comparative examples 1-4

As can be seen by combining tables 1 and 2, relative to (D _v 10+D _v 90)/D _v 50、D _max And D _min The comparative examples CE1 to CE4, examples E1 to E9, which are not in any of the limited ranges, are generally superior in air stability and first effect, rate discharge performance and cycle performance.

As can be seen from comparative example E1 and comparative example CE1, the difference in physicochemical properties between them is mainly found in E1 (D _v 10+D _v 90)/D _v 50 is 1.48, and in CE1 (D _v 10+D _v 90)/D _v 50 is 1.69. E1 is superior to CE1 in charge-discharge capacity, initial effect, rate discharge, cycle retention rate and 2h discharge performance at 25deg.C and 60% humidity, and is particularly superior to CE1 in cycle retention rate and 2h discharge performance at 25deg.C and 60% humidity.

As can be seen from comparative example E2 and comparative example CE2, the physicochemical properties of the two differ mainly in E2 (D _v 10+D _v 90)/D _v 50 is 1.41, and in CE2 (D _v 10+D _v 90)/D _v 50 is 1.28. E2 is superior to CE2 in charge-discharge capacity, initial effect, rate discharge, cycle retention rate and 2h discharge performance at 25deg.C and 60% humidity, and is particularly superior to CE2 in cycle retention rate and 2h discharge performance at 25deg.C and 60% humidity.

As can be seen from comparing E3 with comparative example CE3, the physicochemical properties of the two differ mainly in D in E3 _max 15.35 μm, and D in CE3 _max 16.30 μm. E3 is superior to CE3 in charge-discharge capacity, initial effect, rate discharge, cycle retention rate and discharge performance after being placed at 25 ℃ and 60% humidity for 2 hours, in particularIs obviously superior to CE3 in discharge performance when being placed for 2 hours at 25 ℃ and 60% humidity.

As can be seen from comparing E4 with comparative example CE4, the physicochemical properties of the two differ mainly in D in E4 _min 0.48 μm, and D in CE4 _min 0.43 μm. E4 is superior to CE4 in charge-discharge capacity, initial effect, rate discharge, cycle retention rate and 2h discharge performance at 25deg.C and 60% humidity, and is particularly superior to CE4 in cycle retention rate and 2h discharge performance at 25deg.C and 60% humidity.

Therefore, the invention can effectively improve the overall performance of the layered oxide positive electrode material, and the obtained layered oxide positive electrode material has good air stability, initial efficiency, rate discharge performance and cycle performance.

What has been described above is merely an exemplary embodiment of the present invention. It should be noted herein that modifications to the invention can be made by those skilled in the art without departing from the inventive concept, and are intended to be within the scope of the invention.

Claims

1. A layered oxide positive electrode material having the general formula:

Na _x Cu _a Mn _b Fe _c M _d O _e

m is selected from one or more of Mg, al, si, ti, cr, co, ni, zn, Y, zr, sb, la, ce, W, F;

minimum particles of the layered oxide cathode materialDiameter D _min ≥0.45μm。

2. The layered oxide cathode material of claim 1, wherein the M is selected from one or more of Mg, al, ti, zn, Y, zr, F.

3. The layered oxide cathode material of claim 2, wherein the M is selected from one or more of Mg, al, ti, zr, F.

4. The layered oxide cathode material according to any one of claims 1 to 3, wherein the layered oxide cathode material has a maximum particle diameter D _max ≤14.00μm。

5. The layered oxide cathode material according to any one of claims 1 to 3, wherein the layered oxide cathode material has a minimum particle diameter D _min ≥0.80μm。

6. The layered oxide cathode material according to any one of claims 1 to 3, wherein D of the layered oxide cathode material _v The particle size of 10 is 0.60-2.20 μm.

7. The layered oxide cathode material of claim 6, wherein D of the layered oxide cathode material _v The particle size of 10 is 0.80-2.10 μm.

8. The layered oxide cathode material according to any one of claims 1 to 3, wherein D of the layered oxide cathode material _v The 50 grain diameter is 2.00-8.00 mu m.

9. The layered oxide cathode material of claim 8, wherein D of the layered oxide cathode material _v The 50 grain diameter is 2.50-7.00 mu m.

10. The layered oxide cathode material according to any one of claims 1 to 3, wherein theD of layered oxide cathode Material _v The particle size of 90 is 3.00-8.00 μm.

11. The layered oxide cathode material of claim 10, wherein D of the layered oxide cathode material _v The particle size of 90 is 3.40-7.50 μm.

12. The layered oxide cathode material according to any one of claims 1 to 3, wherein the sphericity Φ of the layered oxide cathode material is 0.55 or more.

13. The layered oxide cathode material according to any one of claims 1 to 3, wherein the BET specific surface area of the layered oxide cathode material is 0.10 to 0.60m ² /g。

14. A layered oxide cathode material according to any one of claims 1 to 3, wherein in an XRD spectrum of the layered oxide cathode material, a ratio I003/I104 of peak intensity I003 of 003 peak to peak intensity I104 of 104 peak is 1.30 to 1.70.

15. The layered oxide cathode material according to any one of claims 1 to 3, wherein the layered oxide cathode material has a tap density TD of 1.80-2.50g/cm ³ 。

16. The layered oxide cathode material of claim 15, wherein the layered oxide cathode material has a tap density TD of 1.85-2.40g/cm ³ 。

17. The layered oxide cathode material according to any one of claims 1 to 3, wherein the layered oxide cathode material has a compacted density PD of 2.80-3.50g/cm at 15kN ³ 。

18. The layered oxide cathode material of claim 17, wherein the layered oxide cathode material has a compacted density PD of 2.80-3.35g/cm at 15kN ³ 。

19. The layered oxide cathode material of claim 17, wherein a difference PD-TD between the compacted density and tap density of the layered oxide cathode material satisfies: 0.40g/cm ³ ≤PD-TD≤1.70 g/cm ³ 。

20. The layered oxide cathode material of claim 19, wherein a difference PD-TD between the compacted density and tap density of the layered oxide cathode material satisfies: 0.40g/cm ³ ≤PD-TD≤1.50g/cm ³ 。

21. The layered oxide cathode material according to any one of claims 1 to 3, wherein a+b+c ranges from 0.70 to 1.00.

22. A layered oxide cathode material according to any one of claims 1 to 3, wherein the ratio d/(a+b+c) is 0 to 0.35.

23. The layered oxide cathode material according to any one of claims 1 to 3, wherein the pH of the layered oxide cathode material is 10.50 to 13.00.

24. The layered oxide cathode material according to any one of claims 1 to 3, wherein a residual Na content of the layered oxide cathode material is 10000 ppm or less.

25. A method of preparing the layered oxide cathode material according to any one of claims 1 to 24, comprising the steps of:

step b: sintering the precursor obtained in the step a; and

step c: and d, cooling the product obtained in the step b.

26. The method of claim 25, wherein step c further comprises pulverizing, sieving after cooling.

27. The method of claim 25 or 26, wherein the sintering in step b is performed in an oxidizing atmosphere.

28. The method of claim 27, wherein the oxidizing atmosphere is compressed air or oxygen.

29. The method according to claim 25 or 26, wherein the sintering temperature in step b is 750 to 1200 ℃ and the sintering time is 10 to 48 hours.

30. The method of claim 29, wherein the sintering temperature in step b is 800 to 1100 ℃.

31. The method of claim 29, wherein the sintering time in step b is 12 to 36 hours.

32. The method of claim 25 or 26, wherein step b comprises a first sintering process, a second sintering process, and optionally a third sintering process, performed sequentially, wherein

33. The method of claim 32, wherein the sintering temperature T1 of the first sintering process satisfies: t1 is more than or equal to 750 ℃ and less than or equal to 850 ℃, and sintering time T1 is 2-10h; and/or

34. A positive electrode composition for a sodium ion secondary battery, comprising the layered oxide positive electrode material according to any one of claims 1 to 24.

35. A sodium ion secondary battery comprising the positive electrode composition according to claim 34.

36. Use of a sodium ion secondary battery according to claim 35 in an energy storage device for solar power generation, wind power generation, smart grid peaking, distribution power stations, backup power sources or communication base stations.