Low-cost lithium cobalt oxide positive electrode material as well as preparation method and application thereof

Abstract

The invention provides a low-cost lithium cobalt oxide positive electrode material and a preparation method and application thereof.The preparation method comprises the steps that firstly, a cobalt source, a lithium source and a sodium source with Dv50 being 3-5 microns are subjected to dry mixing treatment, and a mixed material is obtained; secondly, the mixed material is subjected to high-temperature sintering treatment, and a sintered material is obtained; and finally, crushing and sieving the sintered material to obtain the low-cost lithium cobalt oxide positive electrode material with Dv50 of 16-21 [mu] m. According to the preparation method provided by the invention, a traditional large-particle cobalt source is replaced with a small-particle cobalt source, a sodium source is introduced as a functional additive, and a simple process of'dry mixing-high-temperature sintering-crushing and sieving 'is matched, so that the use amount of a lithium source does not need to be additionally increased in the preparation process, and the sintering temperature does not need to be increased; the cost is controlled in the whole process from raw material selection to process execution, so that the precursor purchase cost, the additional consumption cost of the lithium source and the high-temperature sintering energy consumption expenditure are remarkably reduced, and the multi-dimensional cost advantage is formed.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery positive electrode materials, in particular to a low-cost lithium cobaltate positive electrode material and a preparation method and application thereof. BACKGROUND

[0002] Lithium ion battery positive electrode materials (LIBs) have been widely used in consumer electronics, electric vehicles, aerospace, etc. due to high energy density, high coulomb efficiency, long service life, no memory effect, low self-discharge characteristics and different chemical potentials of electrode design. In recent years, lithium ion batteries have occupied a major market share in the fields of electric vehicles, energy storage systems and mobile electronic devices.

[0003] Since the commercialization of lithium ion batteries from Japan Sony Company in 1990, the positive electrode material has gradually developed into the most critical material for improving the performance of lithium ion batteries. Lithium cobaltate is widely used in the digital 3C field due to its high capacity, high compaction density and high voltage platform. In order to ensure the normal endurance of digital products and the demand for lightness and convenience, the development of high-volume energy density positive electrode materials has become the focus of current research, and large particle size high-voltage LiCoO2 has become a hot research direction. Good LiCoO2 preparation is largely dependent on the precursor Co3O4.

[0004] However, large particle size Co3O4 has problems such as poor sphericity and cracking in actual production, which will further affect the electrochemical performance and cycle stability of LiCoO2 positive electrode. The particle size of traditional large particle Co3O4 is 16-19 μm, and large particle LiCoO2 is generated after mixing and sintering with lithium source. Large particle Co3O4 has problems such as higher price than small particle Co3O4, complex reaction condition control, long synthesis time, etc. If small particle Co3O4 is simply used to synthesize large particle LiCoO2, more lithium source and higher sintering temperature are required.

[0005] Therefore, there is an urgent need for a low-cost lithium cobaltate positive electrode material and a preparation method and application thereof to solve the above technical problems. SUMMARY

[0006] In view of the technical problems in the background art, the application provides a low-cost lithium cobaltate positive electrode material and a preparation method and application thereof, aiming to solve the technical problems of high production cost, long reaction time and complex reaction condition control in the preparation method of the existing lithium cobaltate positive electrode material.

[0007] In a first aspect, the embodiments of the application provide a preparation method of a low-cost lithium cobaltate positive electrode material, comprising: S10, dry mixing a cobalt source, a lithium source and a sodium source to obtain a mixture; S20, high-temperature sintering treatment is performed on the mixed material to obtain a sintered material; S30, the sintered material is crushed and sieved to obtain the low-cost lithium cobalt oxide positive electrode material; In the step S10, the volume-weighted median particle size Dv50 of the cobalt source is 3-5 μm; in the step S30, the volume-weighted median particle size Dv50 of the low-cost lithium cobalt oxide positive electrode material is 16-21 μm.

[0008] Preferably, in the step S10, the cobalt source includes at least one of tricobalt tetroxide, cobalt carbonate, cobalt hydroxide and cobalt oxyhydroxide.

[0009] Preferably, in the step S10, the lithium source includes at least one of battery-grade lithium carbonate and battery-grade lithium hydroxide.

[0010] Preferably, in the step S10, the molar ratio of the lithium source to the cobalt source is (1.01-1.04):1.

[0011] Preferably, in the step S10, the sodium source includes any one of sodium carbonate and sodium oxide; the addition amount of the sodium source is 0.1%-0.3% of the total feeding amount of the lithium source and the cobalt source.

[0012] Preferably, in the high-temperature sintering treatment of the step S20, the sintering temperature is 1020-1080℃, the heating rate is 3-10℃ / min, and the holding time is 5-10 h.

[0013] Preferably, in the step S30, the chemical formula of the low-cost lithium cobalt oxide positive electrode material is Li a Na b CoO2, 0.7≤a≤1, 0≤b≤0.3.

[0014] Preferably, the step S30 specifically includes: uniformly laying the sintered material in the sagger and performing block division treatment; after the sintered material is cooled to room temperature, the sintered material is taken out and crushed; and the crushed sintered material is sieved through a 325-mesh sieve to obtain the low-cost lithium cobalt oxide positive electrode material.

[0015] In a second aspect, the embodiments of the present application provide a low-cost lithium cobalt oxide positive electrode material, which is prepared by the preparation method of the low-cost lithium cobalt oxide positive electrode material according to any one of the above.

[0016] In a third aspect, the embodiments of the present application provide an application of the low-cost lithium cobalt oxide positive electrode material in a lithium ion battery.

[0017] Beneficial effects: the application provides a low-cost lithium cobalt oxide positive electrode material and a preparation method and application thereof. The preparation method comprises the following steps: firstly, a cobalt source, a lithium source and a sodium source with a volume-weighted median particle size Dv50 of 3-5 mu m are dry-mixed to obtain a mixture; secondly, the mixture is subjected to high-temperature sintering to obtain a sintered material; and finally, the sintered material is crushed and sieved to obtain a low-cost lithium cobalt oxide positive electrode material with a Dv50 of 16-21 mu m. The preparation method provided by the application can replace the traditional large-particle cobalt source with a smaller-particle cobalt source, and introduce a sodium source as a functional additive to match the simple process of “dry mixing-high temperature sintering-crushing and sieving”, so that the solid-phase sintering preparation process does not need to increase the amount of lithium source or improve the sintering temperature, and the cost is controlled throughout the selection of raw materials and the execution of the process, thereby significantly reducing the procurement cost of the precursor, the additional consumption cost of the lithium source and the high-temperature sintering energy consumption, forming a multi-dimensional cost advantage; at the same time, the above process is fully compatible with the existing lithium cobalt oxide production line equipment, and the operation process is simple, which greatly reduces the technical threshold and equipment modification investment of large-scale production, and the lithium cobalt oxide positive electrode material with the target particle size obtained finally not only has highly consistent morphology and electrical performance with the product prepared by the conventional method, but also has better electrochemical performance and higher capacity, truly realizing the coordination and unity of low cost and high performance, and providing strong support for the industrialization of the low-cost lithium cobalt oxide positive electrode material. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the application, the drawings used in the application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0019] Figure 1 The flowchart of the preparation method of the low-cost lithium cobalt oxide positive electrode material provided by the embodiment of the application is shown in the figure. Figure 2 The SEM image of the low-cost lithium cobalt oxide positive electrode material prepared in Example 1 at 500 times is shown in the figure. Figure 3 The SEM image of the low-cost lithium cobalt oxide positive electrode material prepared in Example 1 at 1000 times is shown in the figure. Figure 4 The SEM image of the low-cost lithium cobalt oxide positive electrode material prepared in Example 2 at 500 times is shown in the figure. Figure 5 The SEM image of the low-cost lithium cobalt oxide positive electrode material prepared in Example 2 at 1000 times is shown in the figure. Figure 6 The SEM image of the low-cost lithium cobalt oxide positive electrode material prepared in Example 3 at 500 times is shown in the figure. Figure 7 SEM image of the low-cost lithium cobalt oxide cathode material prepared for Example 3 at 1000 times magnification; Figure 8 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 1 at 500 times magnification; Figure 9 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 1 at 1000 times magnification; Figure 10 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 2 at 500 times magnification; Figure 11 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 2 at 1000 times magnification; Figure 12 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 3 at 500 times magnification; Figure 13 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 3 at 1000 times magnification; Figure 14 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 4 at 500 times magnification; Figure 15 SEM image of the lithium cobalt oxide cathode material prepared for Comparative Example 4 at 1000 times magnification. DETAILED DESCRIPTION

[0020] The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only used to more clearly illustrate the technical solution of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0022] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0023] Reference to“an embodiment” herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase“in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all referring to a common set of embodiments, of the application, differing embodiments can be described.

[0024] At present, the traditional process selects large particle Co3O4 to synthesize LiCoO2, and the particle size is 16-19 μm. There is also a choice of using small particle Co3O4 to synthesize large particle LiCoO2, which requires higher sintering temperature and more lithium source to help the growth of Co3O4. Therefore, the present application introduces special additives for solid phase sintering while using small particle Co3O4, without consuming additional lithium source and temperature, to achieve the same particle size, electrical performance and other parameters as the traditional large particle Co3O4 for synthesizing LiCoO2 cathode material. The method is simple to operate, more conducive to cost reduction, and industrial production.

[0025] Please refer to Figure 1 , Figure 1 The process flow diagram of the preparation method of the low-cost lithium cobaltate cathode material provided by the embodiments of the application is shown. In a first aspect, the embodiments of the application provide a preparation method of battery-grade iron phosphate, comprising the following steps: S10, dry mixing treatment of a cobalt source, a lithium source and a sodium source to obtain a mixture.

[0026] Specifically, the step S10 further comprises: Dry mixing treatment of a cobalt source, a lithium source and a sodium source with a volume-weighted median particle size Dv50 of 3-5 μm to obtain a mixture; wherein the cobalt source includes at least one of tricobalt tetroxide, cobalt carbonate, cobalt hydroxide and hydroxyl cobalt oxide, the lithium source includes at least one of battery-grade lithium carbonate and battery-grade lithium hydroxide, and the molar ratio of the lithium source to the cobalt source is (1.01-1.04):1.

[0027] Specifically, first, a small particle cobalt source with a Dv50 of 3-5 pm is used, which has a larger specific surface area, and can achieve more sufficient particle contact when mixed with lithium source and sodium source by dry method, reducing the problem of local composition unevenness, laying a foundation for uniform reaction in subsequent high temperature sintering; second, the cobalt source includes various choices such as tricobalt tetroxide and cobalt carbonate, and the lithium source is limited to battery-grade lithium carbonate and lithium hydroxide, which not only broadens the flexibility of raw material procurement (raw materials can be selected according to the supply chain or cost), but also ensures the purity of the lithium source through the battery-grade standard, reducing the adverse effects of impurities on the electrical properties of the final product; finally, the molar ratio of lithium source to cobalt source is controlled at (1.01-1.04):1, and the slight excess of lithium source can compensate for the loss of lithium during high temperature sintering, ensuring that the target product (lithium cobalt oxide) is fully reacted, and avoiding the reduction of material electrochemical performance caused by insufficient lithium.

[0028] In the S10 step: the sodium source includes any one of sodium carbonate and sodium oxide; the addition amount of the sodium source is 0.1%-0.3% of the total feeding mass of the lithium source and the cobalt source.

[0029] Specifically, the sodium source is limited to sodium carbonate or sodium oxide, both of which are common inorganic compounds of industrial grade, and the raw material procurement cost is lower than that of organic sodium salt (such as sodium acetate) or rare sodium compounds, which directly meets the preparation positioning of "low-cost lithium cobalt oxide"; at the same time, these two sodium sources have stable chemical properties and will only participate in doping reactions during high temperature sintering, without decomposing to produce volatile harmful gases (such as CO and CH4 that organic sodium salts may produce) or introducing complex impurities, which can avoid polluting the final product and ensure the crystal purity of lithium cobalt oxide, laying a foundation for stable electrical properties. At the same time, the sodium source doping amount of 0.1%-0.3% ensures that the sodium element functions to "promote the sintering and growth of small particle cobalt source, and stabilize the lithium cobalt oxide lattice" with the lower limit of 0.1%, and avoids the influence of lattice distortion on electrical properties caused by excessive sodium with the upper limit of 0.3%, accurately balancing function and performance, and finally providing support for low-cost preparation of lithium cobalt oxide positive electrode material with qualified particle size and electrical properties.

[0030] S20, the mixture is subjected to high temperature sintering treatment to obtain a sintered material.

[0031] Specifically, the S20 step further includes: The mixture is subjected to high temperature sintering treatment to obtain a sintered material; wherein the sintering temperature is 1020-1080℃, the heating rate is 3-10℃ / min, and the holding time is 5-10h.

[0032] Specifically, the sintering temperature of 1020-1080℃ can ensure that the small particle cobalt source and the lithium source fully react to form lithium cobalt oxide, promote the particles to grow to the target particle size (adapt to the subsequent 16-21 μm product requirements), and avoid excessive lithium volatilization or excessive grain growth caused by high temperature, which affects the electrical properties; the heating rate of 3-10℃ / min can make the temperature of the mixture rise uniformly, reduce defects such as cracking and uneven sintering caused by thermal stress, and ensure the density of the material structure; the holding time of 5-10h can make the reaction proceed completely, avoid the residue of unreacted raw materials, and control the grain size in a reasonable range to stabilize the layered structure of lithium cobalt oxide and improve the electrochemical performance. The three work together to achieve "full reaction, controllable particle size, stable performance, and energy consumption adaptation", which provides key process support for subsequent preparation of high-quality and low-cost lithium cobalt oxide cathode materials.

[0033] S30, the sintered material is crushed and sieved to obtain a low-cost lithium cobalt oxide cathode material.

[0034] Specifically, the S30 step further comprises: The sintered material is uniformly laid in the sagger and subjected to block division treatment (for example, 8x8 blocks), and after the sintered material cools to room temperature, it is taken out for crushing treatment (including coarse crushing with a jaw crusher and a roller, and fine crushing with an air flow mill). After the crushed sintered material is sieved through a 325 mesh screen to remove coarse impurities, a low-cost lithium cobalt oxide cathode material with a Dv50 of 16-21 μm is obtained, and the chemical formula of the low-cost lithium cobalt oxide cathode material is Li a Na b CoO2, 0.7≤a≤1, 0≤b≤0.3.

[0035] Specifically, uniformly laying and dividing the sintered material can ensure that the temperature difference between the inside and outside of the material is small during cooling, the cooling is uniform, and the material is prevented from cracking or structural damage due to thermal stress, and the subsequent crushing is easier to achieve small block crushing and reduce the generation of large hard agglomerates; after cooling, the combination of "jaw crusher + roller coarse crushing + air flow mill fine crushing" can efficiently break the large structure of the sintered material, and then accurately control the fine crushing particle size to avoid uneven particle size or over-crushing caused by a single crushing method; sieving through a 325 mesh screen can effectively remove coarse impurities that have not been completely crushed, ensuring that the final product has a Dv50 of 16-21 μm within the target range; and the chemical formula of the product Li a Na b CoO2 (0.7≤a≤1, 0≤b≤0.3) defines a reasonable content range for lithium and sodium elements, which ensures the stability of the layered crystal structure of lithium cobalt oxide (avoids structural defects caused by insufficient lithium), and optimizes the electrochemical performance through controllable sodium doping amount, ultimately providing key post-processing support for obtaining low-cost lithium cobalt oxide cathode materials with uniform particle size, standard purity, and stable performance.

[0036] In a second aspect, the embodiments of the present application provide a low-cost lithium cobalt oxide cathode material, which is prepared by the preparation method of the low-cost lithium cobalt oxide cathode material according to any one of the above.

[0037] In the technical solution of the embodiments of the present application, the low-cost lithium cobalt oxide cathode material is prepared by the preparation method of the low-cost lithium cobalt oxide cathode material as above, has the advantages of significant cost advantage (relying on small particle cobalt source, cheap sodium source and process without additional lithium consumption / high temperature), excellent physical and chemical properties (uniform particle size Dv50=16-21 μm, high purity, stable layered structure) and excellent electrochemical performance (high specific capacity, good cycle stability), and can well meet the market needs.

[0038] In a third aspect, the embodiments of the present application provide an application of the low-cost lithium cobalt oxide cathode material as above in a lithium ion battery.

[0039] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation on the present application. If the specific technology or condition is not specified in the embodiments, the technology or condition described in the literature in the art or according to the product manual is used. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0040] Embodiment 1: The embodiment 1 provides a low-cost lithium cobalt oxide cathode material and a preparation method thereof. The chemical formula of the low-cost lithium cobalt oxide cathode material is Li a Na b CoO2, 0.7≤a≤1, 0≤b≤0.3, and the preparation method comprises the following steps: Step (1): Cobalt sesquioxide with a particle size Dv50=3-5 μm and battery-grade lithium carbonate are weighed according to a Li / Co molar ratio of 1.025, and then 0.2 wt% of sodium carbonate is added and uniformly mixed by dry method to obtain a mixture.

[0041] Step (2): The mixture is subjected to high-temperature sintering treatment to obtain a sintered material; wherein the sintering temperature is increased from room temperature (25℃) to 1050℃ at a rate of 5℃ / min, and the temperature is maintained for 10 h.

[0042] Step (3): The sintered material is uniformly laid in a sagger and subjected to 8x8 block division treatment. After the sintered material is cooled to room temperature, it is taken out, coarsely crushed by a jaw crusher and a pair of rollers, and then finely crushed by an air jet mill. The particle size Dv50 of the crushed material is controlled to be 15-21 μm, and the material is sieved by a 325 mesh screen to obtain the low-cost lithium cobalt oxide cathode material.

[0043] Embodiment 2: The embodiment 2 provides a low-cost lithium cobaltate positive electrode material and a preparation method thereof. The chemical formula of the low-cost lithium cobaltate positive electrode material is Li a Na b CoO2, 0.7<=a<=1, 0<=b<=0.3. The preparation method is basically the same as that of the embodiment 1, and the difference is only in steps (1) and (2): Step (1): Cobalt tetraoxide with a particle size Dv50=3-5 um and battery-grade lithium carbonate are weighed according to a Li / Co molar ratio of 1.01, and then 0.1wt% of sodium carbonate is added to uniformly mix by dry method to obtain a mixed material.

[0044] Step (2): The mixed material is subjected to high-temperature sintering treatment to obtain a sintered material; wherein the sintering temperature is increased to 1080 DEG C at a rate of 5 DEG C / min from room temperature (25 DEG C) and is kept for 10h.

[0045] Embodiment 3: The embodiment 3 provides a low-cost lithium cobaltate positive electrode material and a preparation method thereof. The chemical formula of the low-cost lithium cobaltate positive electrode material is Li a Na b CoO2, 0.7<=a<=1, 0<=b<=0.3. The preparation method is basically the same as that of the embodiment 1, and the difference is only in steps (1) and (2): Step (1): Cobalt tetraoxide with a particle size Dv50=3-5 um and battery-grade lithium carbonate are weighed according to a Li / Co molar ratio of 1.04, and then 0.3wt% of sodium carbonate is added to uniformly mix by dry method to obtain a mixed material.

[0046] Step (2): The mixed material is subjected to high-temperature sintering treatment to obtain a sintered material; wherein the sintering temperature is increased to 1020 DEG C at a rate of 5 DEG C / min from room temperature (25 DEG C) and is kept for 10h.

[0047] Comparative Example 1: The comparative example 1 provides a lithium cobaltate positive electrode material and a preparation method thereof. The chemical formula of the lithium cobaltate positive electrode material is LiCoO2. The preparation method is basically the same as that of the embodiment 1, and the difference is only in step (1): Step (1): Cobalt tetraoxide with a particle size Dv50=16-19 um and battery-grade lithium carbonate are weighed according to a Li / Co molar ratio of 1.025, and then uniformly mixed by dry method to obtain a mixed material.

[0048] Comparative Example 2: Comparative Example 2 provides a lithium cobalt oxide cathode material and a preparation method thereof, the chemical formula of the lithium cobalt oxide cathode material is LiCoO2, the preparation method is substantially the same as the preparation method of Example 1, and the only difference is that steps (1) and (2) are as follows: Step (1): tricobalt tetraoxide with a particle size Dv50 = 3-5 pm and battery-grade lithium carbonate are weighed according to a Li / Co molar ratio of 1.025, and then uniformly mixed by dry method to obtain a mixture.

[0049] Step (2): the mixture is subjected to high-temperature sintering treatment to obtain a sintered material; during the high-temperature sintering treatment, the sintering temperature is increased from room temperature (25°C) to 1080°C at a rate of 5°C / min, and the temperature is maintained for 10 h.

[0050] Comparative Example 3: Comparative Example 3 provides a lithium cobalt oxide cathode material and a preparation method thereof, the chemical formula of the lithium cobalt oxide cathode material is Li a Na b CoO2, 0.7≤a≤1, 0≤b≤0.3, the preparation method is substantially the same as the preparation method of Example 1, and the only difference is that step (1) is as follows: Step (1): tricobalt tetraoxide with a particle size Dv50 = 3-5 pm and battery-grade lithium carbonate are weighed according to a Li / Co molar ratio of 1.01, 0.1wt% of sodium carbonate is added, and then uniformly mixed by dry method to obtain a mixture.

[0051] Comparative Example 4: Comparative Example 4 provides a lithium cobalt oxide cathode material and a preparation method thereof, the chemical formula of the lithium cobalt oxide cathode material is LiCoO2, the preparation method is substantially the same as the preparation method of Example 1, and the only difference is that steps (1) and (2) are as follows: Step (1): tricobalt tetraoxide with a particle size Dv50 = 3-5 pm and battery-grade lithium carbonate are weighed according to a Li / Co molar ratio of 1.04, and then uniformly mixed by dry method to obtain a mixture.

[0052] Step (2): the mixture is subjected to high-temperature sintering treatment to obtain a sintered material; during the high-temperature sintering treatment, the sintering temperature is increased from room temperature (25°C) to 1080°C at a rate of 5°C / min, and the temperature is maintained for 10 h.

[0053] Please refer to Figures 2 to 15 , Figures 2 to 15 respectively, are SEM (Scanning Electron Microscope Image) images of the lithium cobalt oxide cathode materials synthesized in Example 1 to Example 3, Comparative Example 1 to Comparative Example 4 under different magnifications; Example 1 ( Figure 2 and Figure 3) and Comparative Example 1 (Example 1) Figure 8 and Figure 9 Compared with Comparative Example 1, the particle size of the lithium cobaltate anode material prepared by doping sodium ions is consistent with the morphology of Comparative Example 1.

[0054] In summary, the main parameters of the tests of Example 1 to Example 3 and Comparative Example 1 to Comparative Example 4 are shown in Table 1: Table 1

[0055] Specifically, the particle size of the lithium cobaltate anode material prepared in Example 1 to Example 3 and Comparative Example 1 to Comparative Example 4 is shown in Table 2: Table 2

[0056] As can be seen from Table 2, the preparation method of Example 1 to Example 3 mixes small particle cobaltosic oxide with lithium carbonate and sodium carbonate, and after sintering, the particle size can reach the particle size effect of the lithium cobaltate anode material prepared in Comparative Example 1. However, as can be seen from the particle size data of Comparative Example 2, in the case of using only small particle cobaltosic oxide without doping sodium, increasing the temperature can make Dv50 reach 16.593um. As can be seen from the particle size data of Comparative Example 2, Comparative Example 3 and Comparative Example 4, using small particle cobaltosic oxide as a cobalt source to synthesize large particle lithium cobaltate requires higher sintering temperature, high Li / Co ratio or doping sodium to achieve; among the above three schemes, the sintering temperature of Comparative Example 3 using sodium doping is lower, its economic cost is the lowest, and it is the easiest to achieve.

[0057] Specifically, the electrical performance parameters of the lithium cobaltate anode material prepared in Example 1 to Example 3 and Comparative Example 1 to Comparative Example 4 are shown in Table 3: Table 3

[0058] As can be seen from Table 3, the electrical properties of the lithium cobalt oxide positive electrode material prepared in Example 1 and Comparative Example 1 are compared, the 0.2C discharge specific capacity of the lithium cobalt oxide positive electrode material prepared in Example 1 is 1.8 mAh / g higher, which indicates that the electrical properties of the cobalt source doped with sodium ions by small particles of tricobalt tetroxide are higher than those of the cobalt source doped with large particles of tricobalt tetroxide; the electrical properties of the lithium cobalt oxide positive electrode material prepared in Example 1 and Comparative Example 2 are compared, the 0.2C discharge specific capacity of the lithium cobalt oxide positive electrode material prepared in Example 1 is 2.2 mAh / g higher, which indicates that the method of doping sodium is better than the electrical properties of increasing the temperature; the electrical properties of the lithium cobalt oxide positive electrode material prepared in Example 1 and Comparative Example 3 are compared, the 0.2C discharge specific capacity of the lithium cobalt oxide positive electrode material prepared in Example 1 is 2.8 mAh / g higher, which indicates that the Li / Co ratio and the insufficient doping amount will affect the electrical properties; the electrical properties of the lithium cobalt oxide positive electrode material prepared in Example 1 and Comparative Example 4 are compared, the 0.2C discharge specific capacity of the lithium cobalt oxide positive electrode material prepared in Example 1 is 3.2 mAh / g higher, which indicates that the method of doping sodium ions is better than the electrical properties of simultaneously increasing the Li / Co ratio and the temperature.

[0059] Compared with the prior art, the low-cost lithium cobalt oxide positive electrode material and the preparation method thereof provided by the application have the following advantages: First, the application proposes a method of synthesizing large-particle lithium cobalt oxide positive electrode material with Dv50 = 16-21 mu m by doping with a cheap additive. The lithium cobalt oxide synthesized by the method has the same particle size and morphology as the lithium cobalt oxide synthesized by the conventional method, and has better electrochemical performance and higher capacity. Second, the application selects sodium ion doping, which is low in price and rich in resources, and compared with the conventional synthesis method, it does not need to increase the Li / Co ratio and the sintering temperature, and is more conducive to cost reduction. Third, the application selects small particles of Dv50 = 3-5 mu m cobalt source to replace large particles of Dv50 = 16-19 mu m cobalt source, which saves the cost of precursors, is simple to operate, has low raw material cost, and is easy to realize industrial production.

[0060] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and playing the same role within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications of the embodiments, combination of part of the components in the embodiments to construct other ways can also be included in the scope of the present application.

Claims

1. A method for preparing a low-cost lithium cobalt oxide cathode material, characterized in that, The application relates to a low-cost lithium cobaltate positive electrode material and a preparation method thereof. S10, a cobalt source, a lithium source and a sodium source are dry-mixed to obtain a mixture; S20, the mixture is subjected to high-temperature sintering treatment to obtain a sintered material; S30, the sintered material is crushed and sieved to obtain the low-cost lithium cobaltate positive electrode material. In the step S10, the volume-weighted median particle size Dv50 of the cobalt source is 3-5 mu m; in the step S30, the volume-weighted median particle size Dv50 of the low-cost lithium cobaltate positive electrode material is 16-21 mu m.

2. The method for preparing the low-cost lithium cobalt oxide cathode material according to claim 1, characterized in that, In the step S10, the cobalt source comprises at least one of tricobalt tetroxide, cobalt carbonate, cobalt hydroxide and hydroxyl cobalt oxide.

3. The method for preparing the low-cost lithium cobalt oxide cathode material according to claim 2, characterized in that, In the step S10, the lithium source comprises at least one of battery-grade lithium carbonate and battery-grade lithium hydroxide.

4. The method for preparing the low-cost lithium cobalt oxide cathode material according to claim 3, characterized in that, In the step S10, the molar ratio of the lithium source to the cobalt source is (1.01-1.04):

1.

5. The method for preparing the low-cost lithium cobalt oxide cathode material according to claim 1, characterized in that, In the step S10, the sodium source comprises any one of sodium carbonate and sodium oxide; the addition amount of the sodium source is 0.1%-0.3% of the total feeding mass of the lithium source and the cobalt source.

6. The method for preparing the low-cost lithium cobalt oxide cathode material according to claim 1, characterized in that, In the high-temperature sintering treatment of the step S20, the sintering temperature is 1020-1080 DEG C, the heating rate is 3-10 DEG C / min, and the holding time is 5-10 h.

7. The method for preparing the low-cost lithium cobalt oxide cathode material according to claim 1, characterized in that, The S30 step: the low-cost lithium cobalt oxide positive electrode material has a chemical formula of Li a Na b CoO2, 0.7≤a≤1, 0≤b≤0.

3.

8. The method for preparing the low-cost lithium cobalt oxide cathode material according to claim 1, characterized in that, The step S30 specifically comprises the following steps: The sintered material is uniformly laid in a sagger and subjected to block drawing treatment, and after the sintered material is cooled to room temperature, the sintered material is taken out and subjected to crushing treatment; the crushed sintered material is sieved through a 325-mesh screen to obtain the low-cost lithium cobaltate positive electrode material.

9. A low cost lithium cobalt oxide cathode material, characterized in that, The low-cost lithium cobaltate positive electrode material is prepared by the preparation method of the low-cost lithium cobaltate positive electrode material in any one of claims 1-8.

10. The low-cost lithium cobaltate positive electrode material in claim 9 is applied to a lithium ion battery.

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