A lithium cobalt oxide ceramic target material, a preparation method and application thereof

Abstract

The present application relates to a kind of lithium cobaltate ceramic target material and its preparation method and application, the preparation method includes the following steps: (1) solvent, organic monomer, crosslinking agent and dispersing agent are heated and stirred, to obtain premix liquid;(2) lithium cobaltate powder is added to the premix liquid, and ball milling is carried out, to obtain lithium cobaltate mixed solution;(3) initiator is mixed into the lithium cobaltate mixed solution, to obtain lithium cobaltate liquid slurry;(4) the lithium cobaltate liquid slurry is injected into mold and is carried out solidification treatment, after demolding, dry treatment is carried out again, to obtain lithium cobaltate green body;(5) the lithium cobaltate green body is sequentially carried out debinding treatment and sintering treatment, to obtain lithium cobaltate ceramic target material.The present application is prepared by gel injection molding and atmospheric sintering process to obtain lithium cobaltate ceramic target material, and the preparation process is simple, low in cost, and easy to mass production.

Description

Technical Field

[0001] This invention relates to the field of target technology, and in particular to a lithium cobalt oxide ceramic target, its preparation method, and its application. Background Technology

[0002] Currently, electronic products are trending towards miniaturization, thinner and lighter designs, and greater portability. This has placed new demands on power supplies, leading to significant attention being paid to lithium-ion solid-state batteries, which offer higher energy density, longer cycle life, and higher operating voltage. Compared to liquid lithium-ion batteries, all-solid-state batteries offer greater safety, higher energy density, and a wider operating temperature range.

[0003] The earliest cathode material for thin-film batteries was TiS2. With the successful development of the high-performance solid-state electrolyte LiPON, lithium cobalt oxide (LiCoO2) has attracted widespread research as a cathode material for LiPON-type solid-state thin-film batteries. Due to its advantages such as high voltage, high specific energy density, good cycle performance, and ease of fabrication, lithium cobalt oxide is currently the mainstream cathode material for lithium-ion batteries. With the development of thin-film solid-state batteries, higher requirements are being placed on the lithium cobalt oxide ceramic target for magnetron sputtering of all-solid-state thin-film batteries.

[0004] CN113564398A discloses a method for preparing lithium-containing aluminum-based powder metallurgy composite materials with added sintering activator, including the following process steps: (1) Mixed powder preparation: Lithium-containing compounds and sintering activator are added to pure aluminum powder, alloy element powder or alloy powder in proportion, and mixed powder is prepared by ball milling. The mass fraction of lithium element in the mixed powder is 0.5wt%-5wt%; (2) Powder forming: The above mixed powder is formed by one or both of cold isostatic pressing or molding. (2) Pressing and forming: The pressing pressure is 100-500MPa and the holding time is 30-300s; (3) Sintering and densification: Sintering and densification is carried out in a vacuum or high-purity argon protective atmosphere, the sintering temperature is 500-640℃ and the holding time is 1-10h to obtain a dense powder metallurgy lithium-containing aluminum-based composite material sintered billet; (4) Plastic processing: The above sintered billet is hot-extruded at an extrusion temperature of 300-500℃ to obtain a powder metallurgy lithium-containing aluminum-based composite material with excellent performance. Among them, the lithium-containing compound in step (1) is one or more of lithium iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, and lithium tetraborate, and the sintering activator is one or two of magnesium powder and calcium hydride.

[0005] Currently, the processes used all involve molding combined with atmospheric pressure sintering to prepare lithium cobalt oxide ceramic targets. This process results in high costs for preparing lithium cobalt oxide ceramic targets.

[0006] Therefore, there is a need to develop a simple, efficient, low-cost, short-cycle, and easily mass-producible method for preparing lithium cobalt oxide ceramic targets in order to reduce the preparation cost. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for preparing lithium cobalt oxide ceramic targets. The lithium cobalt oxide ceramic targets are prepared through gel casting and atmospheric pressure sintering processes. The preparation process is simple, low-cost, and easy for mass production.

[0008] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a lithium cobalt oxide ceramic target, the method comprising the following steps: (1) The solvent, organic monomer, crosslinking agent and dispersant are heated and stirred to obtain a premixed solution; (2) Add lithium cobalt oxide powder to the premixed liquid and ball mill it to obtain a lithium cobalt oxide mixture; (3) Initiator is mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry; (4) The lithium cobalt oxide liquid slurry is injected into a mold for solidification, demolded, and then dried to obtain a lithium cobalt oxide green embryo; (5) The lithium cobalt oxide green stock is subjected to degreasing and sintering treatment in sequence to obtain lithium cobalt oxide ceramic target material.

[0009] This invention prepares lithium cobalt oxide ceramic targets through gel casting and atmospheric pressure sintering. First, a premixed liquid is prepared, then lithium cobalt oxide powder is added to the premixed liquid and ball-milled to uniformly disperse the powder, forming a high-solids-content lithium cobalt oxide mixture. Next, an initiator is added to the mixture, initiating the polymerization reaction of organic monomers and crosslinking agents to form a three-dimensional gel network. The lithium cobalt oxide powder is fixed within this network, resulting in a high-solids-content, uniformly distributed lithium cobalt oxide liquid slurry. During the curing process, the organic monomers and crosslinking agents undergo polymerization to form a three-dimensional network structure, fixing the lithium cobalt oxide powder. Drying removes the solvent. Finally, degreasing and sintering are performed sequentially. Degreasing removes organic monomers, crosslinking agents, and other organic matter, preventing defects during sintering. High-temperature sintering then causes diffusion and densification between the lithium cobalt oxide particles, forming a high-density, high-strength lithium cobalt oxide ceramic target.

[0010] As a preferred embodiment of the present invention, the solvent includes water.

[0011] The solvent used in this invention is water, not an organic solvent. This is because water is the solvent for the dispersant used in this invention, which has good solubility in water and can better disperse lithium cobalt oxide powder, forming a stable and well-dispersed lithium cobalt oxide liquid slurry. If an organic solvent is used, the dispersibility and stability of the lithium cobalt oxide liquid slurry will decrease due to the poor solubility of the dispersant in the organic solvent. At the same time, when water is used as the solvent, the polymerization reaction of organic monomers and crosslinking agents is easier to control, resulting in better curing effect. However, the high volatility of organic solvents will lead to uneven shrinkage of the slurry during the curing process, affecting the curing effect. In the degreasing process, when water is used as the solvent, the organic content in the lithium cobalt oxide preform is lower, making the degreasing process easier and reducing the risk of defects during degreasing. When an organic solvent is used as the solvent, the organic content in the lithium cobalt oxide preform is higher, requiring higher temperatures and longer times for degreasing, increasing the risk of defects.

[0012] Preferably, the organic monomer includes any one or a combination of at least two of acrylamide, methacrylamide, or styrene, wherein typical but non-limiting combinations include: a combination of acrylamide and methacrylamide, a combination of acrylamide and styrene, a combination of methacrylamide and styrene, and a combination of acrylamide, methacrylamide, and styrene.

[0013] Preferably, the crosslinking agent comprises any one or a combination of at least two of N,N-methylenebisacrylamide, divinylbenzene, or methyl acrylate, wherein typical but non-limiting combinations include: a combination of N,N-methylenebisacrylamide and divinylbenzene, a combination of N,N-methylenebisacrylamide and methyl acrylate, a combination of divinylbenzene and methyl acrylate, or a combination of N,N-methylenebisacrylamide, divinylbenzene, and methyl acrylate.

[0014] Preferably, the dispersant comprises any one or a combination of at least two of ammonium polyacrylate, polyethylene glycol, or sodium dodecyl sulfate, wherein typical but non-limiting combinations include: a combination of ammonium polyacrylate and polyethylene glycol, a combination of ammonium polyacrylate and sodium dodecyl sulfate, a combination of polyethylene glycol and sodium dodecyl sulfate, or a combination of ammonium polyacrylate, polyethylene glycol, and sodium dodecyl sulfate.

[0015] As a preferred technical solution of the present invention, the heating temperature of the heating and stirring is 40-80℃, for example, it can be 40℃, 50℃, 60℃, 70℃ or 80℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0016] Preferably, the stirring speed of the heating and stirring is 200-600 r / min, for example, it can be 200 r / min, 300 r / min, 400 r / min, 500 r / min or 600 r / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0017] Preferably, the heating and stirring time is 5-20 minutes, for example, 5 minutes, 7 minutes, 10 minutes, 13 minutes, 15 minutes or 20 minutes, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0018] Preferably, the rotational speed of the ball mill is 150-200 r / min, for example, it can be 150 r / min, 160 r / min, 170 r / min, 180 r / min, 190 r / min or 200 r / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0019] Preferably, the ball milling time is 5-15 hours, for example, 5 hours, 7 hours, 10 hours, 13 hours or 15 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0020] Preferably, the particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 1-5 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0021] This invention limits the particle size of lithium cobalt oxide solid particles in the ball-milled lithium cobalt oxide mixture to 1-5 μm. Particles within this size range have a large specific surface area, allowing for relatively good dispersion in the mixture. During sintering, the particles maintain close contact, which is beneficial for improving the density of the lithium cobalt oxide ceramic target and forming a more uniform microstructure, thereby enhancing the overall performance of the lithium cobalt oxide ceramic target. If the particle size of the lithium cobalt oxide solid particles in the ball-milled lithium cobalt oxide mixture is less than 1 μm, the specific surface area of ​​the particles will be very large, resulting in excessively high surface energy and a tendency for agglomeration. Even with dispersion treatment of the mixture, it will be difficult to maintain a long-term uniform dispersion. Agglomerated particles will affect the microstructure and performance of the lithium cobalt oxide ceramic target, making it less effective. The method achieves the expected results; however, if the particle size of the lithium cobalt oxide solid particles in the ball-milled lithium cobalt oxide mixture is greater than 5 μm, the large particle size will result in larger gaps between the particles, making it difficult to completely fill them during sintering. This leads to more pores inside the lithium cobalt oxide ceramic target, reducing its density. This will decrease the mechanical properties of the lithium cobalt oxide ceramic target, such as hardness and strength, and will also affect its electrical properties. Furthermore, larger particle size requires higher sintering temperatures and longer sintering times to achieve better sintering results. This not only increases production costs but also causes excessive grain growth and phase transformation in the lithium cobalt oxide ceramic target at high temperatures, further reducing the performance of the prepared lithium cobalt oxide ceramic target.

[0022] As a preferred technical solution of the present invention, the initiator includes any one or a combination of at least two of ammonium persulfate, hydrogen peroxide, or potassium dichromate, wherein typical but non-limiting combinations include: a combination of ammonium persulfate and hydrogen peroxide, a combination of ammonium persulfate and potassium dichromate, a combination of hydrogen peroxide and potassium dichromate, and a combination of ammonium persulfate, hydrogen peroxide, and potassium dichromate.

[0023] Preferably, based on 100 parts by mass of lithium cobalt oxide powder, the lithium cobalt oxide liquid slurry comprises 100 parts of lithium cobalt oxide powder, 60-80 parts of solvent, 3-20 parts of organic monomer, 0.3-2 parts of crosslinking agent, 0.2-1 parts of dispersant, and 1-5 parts of initiator. The number of parts of solvent can be 60, 65, 70, 75, or 80 parts; the number of parts of organic monomer can be 3, 5, 10, 15, or 20 parts; the number of parts of crosslinking agent can be 0.3, 0.5, 1, 1.5, or 2 parts; the number of parts of dispersant can be 0.2, 0.4, 0.6, 0.8, or 1 part; and the number of parts of initiator can be 1, 2, 3, 4, or 5 parts, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] As a preferred technical solution of the present invention, step (3) further includes vacuum defoaming treatment of the lithium cobalt oxide mixture before mixing.

[0025] Preferably, the vacuum degree of the vacuum degassing process is -0.08 to -0.1 MPa, for example, it can be -0.08 MPa, -0.085 MPa, -0.09 MPa, -0.095 MPa or -0.1 MPa, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0026] Preferably, the mixing in step (3) is carried out by stirring.

[0027] Preferably, the stirring speed for mixing in step (3) is 200-400 r / min, for example, it can be 200 r / min, 250 r / min, 300 r / min, 350 r / min or 400 r / min, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0028] In this invention, the prepared lithium cobalt oxide mixture is first subjected to vacuum defoaming treatment. Then, an initiator is added to the lithium cobalt oxide mixture, and the stirring speed during the initiator addition process is limited to 200-400 r / min to prevent the generation of bubbles during the initiator addition process. This ensures that the prepared lithium cobalt oxide liquid slurry is bubble-free. This is because the presence of bubbles will lead to uneven distribution of lithium cobalt oxide powder in the lithium cobalt oxide liquid slurry, affecting densification in subsequent curing, degreasing, and sintering processes. At the same time, bubbles will form defects during sintering. Therefore, controlling the absence of bubbles in the lithium cobalt oxide liquid slurry can significantly improve the quality and performance of lithium cobalt oxide ceramic targets.

[0029] Preferably, the mixing time in step (3) is 2-5 hours, for example, 2 hours, 3 hours, 4 hours or 5 hours, but not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0030] As a preferred technical solution of the present invention, the curing temperature is 60-100℃, for example, it can be 60℃, 70℃, 80℃, 90℃ or 100℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0031] Preferably, the curing time is 3-8 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours or 8 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0032] Preferably, the drying temperature is 40-60°C, for example, 40°C, 45°C, 50°C, 55°C or 60°C, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0033] Preferably, the drying time is 24-48 hours, for example, 24 hours, 30 hours, 36 hours, 42 hours or 48 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0034] As a preferred technical solution of the present invention, the temperature of the degreasing treatment is 500-600℃, for example, it can be 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0035] Preferably, the degreasing treatment time is 1-5 hours, for example, it can be 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0036] Preferably, the sintering temperature is 950-1000℃, for example, 950℃, 960℃, 970℃, 980℃, 990℃ or 1000℃, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0037] Preferably, the sintering time is 1-5 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0038] Preferably, the sintering pressure is 90-110 kPa, for example, 90 kPa, 95 kPa, 100 kPa, 105 kPa or 110 kPa, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0039] As a preferred technical solution of the present invention, the preparation method includes the following steps: (1) Taking 100 parts by mass of lithium cobalt oxide powder, 60-80 parts by mass of solvent, 3-20 parts by mass of organic monomer, 0.3-2 parts by mass of crosslinking agent and 0.2-1 parts by mass of dispersant are stirred and mixed at a temperature of 40-80℃ to obtain a premixed solution; (2) Add 100 parts of lithium cobalt oxide powder to the premixed liquid and ball mill at a speed of 150-200 r / min for 5-15 h to obtain a lithium cobalt oxide mixture. The particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 1-5 μm. (3) The lithium cobalt oxide mixture is subjected to vacuum defoaming treatment. After defoaming, 1-5 parts of initiator are mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry. The stirring speed during the mixing process is 200-400 r / min and the stirring time is 2-5 h. (4) The lithium cobalt oxide liquid slurry is injected into the mold and cured at a temperature of 60-100℃ for 3-8 hours. After demolding, it is dried at a temperature of 40-60℃ for 24-48 hours to obtain lithium cobalt oxide green embryo. (5) The lithium cobalt oxide green embryo is subjected to degreasing treatment at a temperature of 500-600℃ for 1-5h and sintering treatment at a temperature of 950-1000℃ for 1-5h and a pressure of 90-110kPa to obtain lithium cobalt oxide ceramic target material.

[0040] In a second aspect, the present invention provides a lithium cobalt oxide ceramic target, which is prepared by the preparation method described in the first aspect.

[0041] The lithium cobalt oxide ceramic target prepared by this invention has excellent properties such as high density, high bending strength, and low resistivity, and can be used to prepare high-performance thin-film battery positive electrode sheets or all-solid-state thin-film lithium batteries.

[0042] Thirdly, the present invention provides an application of the lithium cobalt oxide ceramic target according to the second aspect in lithium-ion battery cathode materials, all-solid-state thin-film battery cathode materials, and electrochromic devices.

[0043] The lithium cobalt oxide ceramic target prepared by this invention can be applied to lithium-ion battery cathode materials, all-solid-state thin-film battery cathode materials, and electrochromic devices, enabling the battery cathode materials or electrochromic devices to have good charge and discharge performance.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention prepares lithium cobalt oxide ceramic target material by gel casting and atmospheric pressure sintering process. Lithium cobalt oxide powder, solvent, organic monomer, crosslinking agent, dispersant and initiator are mixed stepwise and mixed evenly to obtain lithium cobalt oxide liquid slurry. The lithium cobalt oxide liquid slurry is injected into the mold for solidification treatment and dried to obtain lithium cobalt oxide green body. After degreasing treatment and sintering treatment, lithium cobalt oxide ceramic target material is directly obtained. The preparation process provided by the present invention is simple, low cost and easy to mass produce. (2) The lithium cobalt oxide ceramic target prepared by the present invention has excellent properties such as high density, high bending strength and low resistivity. The density can reach more than 99.1%, the bending strength can reach more than 123 MPa, and the resistivity can be controlled within 2800 Ω·cm. It can be used to prepare high-performance thin film battery positive electrode or all-solid-state thin film lithium battery, so that the battery positive electrode material or electrochromic device has good charge and discharge performance. Attached Figure Description

[0045] Figure 1This is a flowchart illustrating the preparation process of the lithium cobalt oxide ceramic target in Embodiment 1 of the present invention. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0047] Example 1 This embodiment provides a method for preparing a lithium cobalt oxide ceramic target. See [link to relevant documentation]. Figure 1 The preparation method, based on parts by weight, includes the following steps: (1) At a temperature of 60℃ and a stirring speed of 400r / min, 70 parts of water, 10 parts of acrylamide, 1 part of N,N-methylenebisacrylamide and 0.5 parts of ammonium polyacrylate (molecular weight of 7 million) were stirred for 15min to obtain a premixed solution. (2) 100 parts of lithium cobalt oxide powder were added to the premixed liquid and ball-milled at 180 r / min for 10 h to obtain a lithium cobalt oxide mixture. The particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture was 3 μm. (3) The lithium cobalt oxide mixture was subjected to vacuum defoaming treatment at a vacuum degree of -0.09MPa. After defoaming, 3 parts of ammonium persulfate were mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry. The stirring speed during the mixing process was 300r / min and the stirring time was 3h. (4) The lithium cobalt oxide liquid slurry is injected into the mold and cured at 80°C for 6 hours. After demolding, it is dried at 50°C for 36 hours to obtain lithium cobalt oxide green embryo. (5) The lithium cobalt oxide green embryo is subjected to degreasing treatment at 550°C for 3 hours and sintering treatment at 980°C for 2.5 hours and 100 kPa to obtain lithium cobalt oxide ceramic target material.

[0048] Example 2 This embodiment provides a method for preparing a lithium cobalt oxide ceramic target. The preparation method includes the following steps, based on parts by mass: (1) At a temperature of 40℃ and a stirring speed of 600r / min, 60 parts of water, 20 parts of methacrylamide, 2 parts of divinylbenzene and 1 part of polyethylene glycol (PEG-600) were stirred for 5 min to obtain a premixed solution; (2) Add 100 parts of lithium cobalt oxide powder to the premixed liquid and ball mill at a speed of 150 r / min for 15 h to obtain a lithium cobalt oxide mixture. The particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 5 μm. (3) The lithium cobalt oxide mixture was subjected to vacuum defoaming treatment at a vacuum degree of -0.08MPa. After defoaming, 5 parts of hydrogen peroxide were mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry. The stirring speed during the mixing process was 200r / min and the stirring time was 5h. (4) The lithium cobalt oxide liquid slurry is injected into the mold and cured at 100°C for 3 hours. After demolding, it is dried at 60°C for 24 hours to obtain lithium cobalt oxide green embryo. (5) The lithium cobalt oxide green embryo is subjected to degreasing treatment at 600℃ for 1h and sintering treatment at 950℃ for 5h and 90kPa to obtain lithium cobalt oxide ceramic target material.

[0049] Example 3 This embodiment provides a method for preparing a lithium cobalt oxide ceramic target. The preparation method includes the following steps, based on parts by mass: (1) Under the conditions of 80℃ and 200r / min, 80 parts of water, 3 parts of styrene, 0.3 parts of methyl acrylate and 0.2 parts of sodium dodecyl sulfate were stirred for 20min to obtain a premixed solution; (2) Add 100 parts of lithium cobalt oxide powder to the premixed liquid and ball mill at a speed of 200 r / min for 5 h to obtain a lithium cobalt oxide mixture. The particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 1 μm. (3) The lithium cobalt oxide mixture was subjected to vacuum defoaming treatment at a vacuum degree of -0.1MPa. After defoaming, 1 part of potassium dichromate was mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry. The stirring speed during the mixing process was 400r / min and the stirring time was 2h. (4) The lithium cobalt oxide liquid slurry is injected into the mold and cured at a temperature of 60°C for 8 hours. After demolding, it is dried at a temperature of 40°C for 48 hours to obtain lithium cobalt oxide green embryo. (5) The lithium cobalt oxide green embryo is subjected to degreasing treatment at 500℃ for 5h and sintering treatment at 1000℃ for 1h and 110kPa to obtain lithium cobalt oxide ceramic target material.

[0050] Example 4 This embodiment provides a method for preparing lithium cobalt oxide ceramic targets. The only difference from Example 1 is that the solvent is replaced by ethanol in the same mass fraction instead of water.

[0051] Example 5 This embodiment provides a method for preparing lithium cobalt oxide ceramic targets. The only difference from Embodiment 1 is that the ball milling speed in step (2) is adjusted from 180 r / min to 100 r / min so that the particle size of the lithium cobalt oxide solid particles in the resulting lithium cobalt oxide mixture is 10 μm, i.e. the particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is too large. All other aspects are the same as in Embodiment 1.

[0052] Example 6 This embodiment provides a method for preparing lithium cobalt oxide ceramic targets. The only difference from Example 1 is that the ball milling speed in step (2) is adjusted from 180 r / min to 300 r / min so that the particle size of the lithium cobalt oxide solid particles in the resulting lithium cobalt oxide mixture is 0.03 μm, i.e. the particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is too small. All other aspects are the same as in Example 1.

[0053] Example 7 This embodiment provides a method for preparing lithium cobalt oxide ceramic targets. The only difference from Embodiment 1 is that, except that step (3) is not vacuum defoaming and sodium persulfate is directly mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry, the rest is the same as in Embodiment 1.

[0054] Example 8 This embodiment provides a method for preparing lithium cobalt oxide ceramic targets. The only difference from Embodiment 1 is that the stirring speed in step (3) during the mixing process is adjusted from 300 r / min to 600 r / min. All other aspects are the same as in Embodiment 1.

[0055] Comparative Example 1 This comparative example provides a method for preparing lithium cobalt oxide ceramic targets. The only difference from Example 1 is that, except for directly mixing water, acrylamide, N,N-methylenebisacrylamide, ammonium polyacrylate, lithium cobalt oxide powder and ammonium persulfate, and ball milling at 180 r / min for 13 h to obtain lithium cobalt oxide liquid slurry, everything else is the same as in Example 1.

[0056] Comparative Example 2 This comparative example provides a method for preparing a lithium cobalt oxide ceramic target. The only difference from Example 1 is that, except for the absence of 0.5 parts of dispersant ammonium polyacrylate in step (1), all other steps are the same as in Example 1. The particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 6 μm.

[0057] Comparative Example 3 This comparative example provides a method for preparing a lithium cobalt oxide ceramic target. The only difference from Example 1 is that step (2) is changed to adding 100 parts of lithium cobalt oxide powder to the premixed solution and stirring at 180 r / min for 10 h to obtain a lithium cobalt oxide mixture. The rest is the same as in Example 1. The particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 12 μm.

[0058] The bulk density of the prepared lithium cobalt oxide ceramic target was tested using the Archimedes method (hydrostatic weighing method). The density of the lithium cobalt oxide ceramic target was calculated using the formula: density (%) = measured density / theoretical density × 100%. The grain size of the lithium cobalt oxide ceramic target was observed using a scanning electron microscope (SEM). The flexural strength of the lithium cobalt oxide ceramic target was tested using a universal testing machine, and the resistivity of the lithium cobalt oxide ceramic target was tested using a resistivity meter. The performance test results are shown in Table 1.

[0059] Table 1 The test results show that: (1) As can be seen from Examples 1 to 3, the lithium cobalt oxide ceramic target prepared by the present invention through gel casting and atmospheric pressure sintering process has excellent properties such as high density, high bending strength and low resistivity. It can be used to prepare high-performance thin film battery positive electrode or all-solid-state thin film lithium battery, so that the battery positive electrode material or electrochromic device has good charge and discharge performance.

[0060] (2) As can be seen from Examples 1 and 4, the solvent in Example 1 is water, and the prepared lithium cobalt oxide ceramic target has a density of 99.3%, a flexural strength of 247 MPa, a resistivity of 1452 Ω·cm, and a grain size of 6.72 μm; while the solvent in Example 4 is ethanol, and the prepared lithium cobalt oxide ceramic target has a density of 96.5%, a flexural strength of 36 MPa, and a resistivity of 2.2 × 10⁻⁶. 6 With an Ω·cm and a grain size of 18.54 μm, it can be seen that when water is used as a solvent, the dispersant used in this invention has good solubility in water, which can better disperse lithium cobalt oxide powder and form a stable and well-dispersed lithium cobalt oxide liquid slurry. If ethanol is used as a solvent, the dispersant is not easy to dissolve in ethanol, and it is easy to precipitate and swell, which changes the slurry system and seriously reduces the density and target performance.

[0061] (3) As can be seen from Examples 1 and 5-6, in Example 1, the ball milling speed in step (2) was 180 r / min, resulting in a lithium cobalt oxide solid particle size of 3 μm in the lithium cobalt oxide mixture. The prepared lithium cobalt oxide ceramic target had a density of 99.3%, a flexural strength of 247 MPa, a resistivity of 1452 Ω·cm, and a grain size of 6.72 μm. In Example 5, the ball milling speed in step (2) was 100 r / min, resulting in a lithium cobalt oxide solid particle size of 3 μm in the lithium cobalt oxide mixture. The particle size of the solid particles is 10 μm. The prepared lithium cobalt oxide ceramic target has a density of 97.3%, a flexural strength of 97 MPa, a resistivity of 58267 Ω·cm, and a grain size of 46.33 μm. In step (2) of Example 6, the ball milling speed is 300 r / min, so that the particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 0.03 μm. The prepared lithium cobalt oxide ceramic target has a density of 97.7%, a flexural strength of 65 MPa, and a resistivity of 5.4 × 10⁻⁶. 6 With an Ω·cm and a grain size of 16.82 μm, this invention limits the ball milling speed to ensure that the particle size of the lithium cobalt oxide solid particles in the ball-milled lithium cobalt oxide mixture is 1-5 μm. Particles in this size range have a large specific surface area, allowing for relatively good dispersion in the mixture. During sintering, the particles are in close contact, which helps to improve the density of the lithium cobalt oxide ceramic target and form a more uniform microstructure, thereby improving the overall performance of the lithium cobalt oxide ceramic target. If the particle size of the lithium cobalt oxide solid particles in the ball-milled lithium cobalt oxide mixture is too large, it will lead to poor sintering activity and reduced density and flexural strength. If the particle size of the lithium cobalt oxide solid particles in the ball-milled lithium cobalt oxide mixture is too small, the slurry will easily agglomerate, and the sintering activity will be high, resulting in abnormal grain growth during sintering and deterioration of performance.

[0062] (4) As can be seen from Examples 1 and 7, the lack of vacuum degassing treatment on the lithium cobalt oxide mixture will lead to cross-linking of the pores in the lithium cobalt oxide green material, which will eventually result in more pores inside the sintered target material, reduced density and bending strength, and increased resistivity.

[0063] (5) As can be seen from Examples 1 and 8, increasing the stirring speed from 300 r / min to 600 r / min will cause slurry splashing, uneven composition, and reduced uniformity of the target material.

[0064] (6) As can be seen from Example 1 and Comparative Example 1, if all raw materials are mixed in one step, the organic matter will not be uniformly coated, the uniformity of the slurry is poor, resulting in uneven target structure, many defects and poor overall performance after sintering.

[0065] (7) As can be seen from Example 1 and Comparative Example 2, if no dispersant is added, the powder will agglomerate, the particle size of the lithium cobalt oxide solid particles will increase, the slurry will have poor dispersibility, and the green density will be low, resulting in lower density and strength after sintering under the same sintering process.

[0066] (8) As can be seen from Example 1 and Comparative Example 3, if the raw materials are not ball-milled and only stirred, the particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture will increase, the solid particles will not be sufficiently dispersed, the sintering activity will be extremely poor, a large number of pores will exist inside the target material, and the performance will be poor.

[0067] In summary, this invention prepares lithium cobalt oxide ceramic targets through gel casting and atmospheric pressure sintering. The preparation process provided by this invention is simple, low-cost, and easy to mass-produce. At the same time, the lithium cobalt oxide ceramic targets prepared by this invention have excellent properties such as high density, high flexural strength, and low resistivity. They can be used to prepare high-performance thin-film battery cathode sheets or all-solid-state thin-film lithium batteries, enabling battery cathode materials or electrochromic devices to have good charge and discharge performance.

[0068] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a lithium cobalt oxide ceramic target, characterized in that, The preparation method includes the following steps: (1) The solvent, organic monomer, crosslinking agent and dispersant are heated and stirred to obtain a premixed solution; (2) Add lithium cobalt oxide powder to the premixed liquid and ball mill it to obtain a lithium cobalt oxide mixture; (3) Initiator is mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry; (4) The lithium cobalt oxide liquid slurry is injected into a mold for solidification, demolded, and then dried to obtain a lithium cobalt oxide green embryo; (5) The lithium cobalt oxide green stock is subjected to degreasing and sintering treatment in sequence to obtain lithium cobalt oxide ceramic target material.

2. The preparation method according to claim 1, characterized in that, The solvent includes water; Preferably, the organic monomer includes any one or a combination of at least two of acrylamide, methacrylamide, or styrene; Preferably, the crosslinking agent includes any one or a combination of at least two of N,N-methylenebisacrylamide, divinylbenzene, or methyl acrylate. Preferably, the dispersant comprises any one or a combination of at least two of ammonium polyacrylate, polyethylene glycol, or sodium dodecyl sulfate.

3. The preparation method according to claim 1 or 2, characterized in that, The heating temperature for the heating and stirring is 40-80℃; Preferably, the rotational speed of the ball mill is 150-200 r / min; Preferably, the ball milling time is 5-15 hours; Preferably, the particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 1-5 μm.

4. The preparation method according to any one of claims 1-3, characterized in that, The initiator includes any one or a combination of at least two of ammonium persulfate, hydrogen peroxide, or potassium dichromate. Preferably, based on 100 parts by mass of lithium cobalt oxide powder, the lithium cobalt oxide liquid slurry comprises 100 parts of lithium cobalt oxide powder, 60-80 parts of solvent, 3-20 parts of organic monomer, 0.3-2 parts of crosslinking agent, 0.2-1 parts of dispersant and 1-5 parts of initiator.

5. The preparation method according to any one of claims 1-4, characterized in that, Step (3) further includes vacuum defoaming treatment of the lithium cobalt oxide mixture before mixing; Preferably, the mixing in step (3) is carried out by stirring; Preferably, the stirring speed in step (3) is 200-400 r / min; Preferably, the mixing time in step (3) is 2-5 hours.

6. The preparation method according to any one of claims 1-5, characterized in that, The curing temperature is 60-100℃; Preferably, the curing time is 3-8 hours; Preferably, the drying temperature is 40-60°C; Preferably, the drying process takes 24-48 hours.

7. The preparation method according to any one of claims 1-6, characterized in that, The degreasing treatment temperature is 500-600℃; Preferably, the degreasing treatment takes 1-5 hours; Preferably, the sintering temperature is 950-1000℃; Preferably, the sintering treatment time is 1-5 hours; Preferably, the pressure of the sintering process is 90-110 kPa.

8. The preparation method according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) Taking 100 parts by mass of lithium cobalt oxide powder, 60-80 parts by mass of solvent, 3-20 parts by mass of organic monomer, 0.3-2 parts by mass of crosslinking agent and 0.2-1 parts by mass of dispersant are stirred and mixed at a temperature of 40-80℃ to obtain a premixed solution; (2) Add 100 parts of lithium cobalt oxide powder to the premixed liquid and ball mill at a speed of 150-200 r / min for 5-15 h to obtain a lithium cobalt oxide mixture. The particle size of the lithium cobalt oxide solid particles in the lithium cobalt oxide mixture is 1-5 μm. (3) The lithium cobalt oxide mixture is subjected to vacuum defoaming treatment. After defoaming, 1-5 parts of initiator are mixed into the lithium cobalt oxide mixture to obtain lithium cobalt oxide liquid slurry. The stirring speed during the mixing process is 200-400 r / min and the stirring time is 2-5 h. (4) The lithium cobalt oxide liquid slurry is injected into the mold and cured at a temperature of 60-100℃ for 3-8 hours. After demolding, it is dried at a temperature of 40-60℃ for 24-48 hours to obtain lithium cobalt oxide green embryo. (5) The lithium cobalt oxide green embryo is subjected to degreasing treatment at a temperature of 500-600℃ for 1-5h and sintering treatment at a temperature of 950-1000℃ for 1-5h and a pressure of 90-110kPa to obtain lithium cobalt oxide ceramic target material.

9. A lithium cobalt oxide ceramic target, characterized in that, The lithium cobalt oxide target is prepared using the preparation method described in any one of claims 1-8.

10. The application of the lithium cobalt oxide ceramic target according to claim 9 in lithium-ion battery cathode materials, all-solid-state thin-film battery cathode materials, and electrochromic devices.

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