Oxide cathode material constructed with isotopic oxygen, and manufacturing method and use thereof

Abstract

To relate to the field of lithium-ion battery technology and provide an oxide cathode material constructed with isotopic oxygen, and a manufacturing method and a use thereof.SOLUTION: Using 18O as a sole oxygen source, a precursor is prepared by a sol-gel method, and then solid-phase sintering is used to synthesize an oxide cathode material containing 18O as an oxygen element. Because the atomic mass of 18O is larger than that of 16O, the covalent bond energy between the transition metal atom and the lattice oxygen is increased, thereby raising the energy barrier for lattice oxygen diffusion. This allows the lattice oxygen in the oxide cathode material to be fixed under high voltage and temperature conditions. Furthermore, this effectively avoids problems such as oxygen escape from the lattice, which can cause crystal structure collapse and shorten the cycle life and safety of the oxide cathode material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an oxide cathode material constructed with isotopic oxygen, a method for manufacturing the same, and its use, and belongs to the technical field of lithium-ion batteries.

Background Art

[0002] Elemental oxygen and its stable isotopes are the main components of rocks and fluids in the earth's crust and mantle and exist stably in nature (relative abundances are 16 O: 99.756%, 17 O: 0.039%, 18 O: 0.205%). The difference between nuclides is due to the difference in the number of neutrons in the atomic nucleus, which further causes an isotope effect, resulting in different physical, chemical, and nuclear properties of the two. For example, 18 O is 12.5% heavier than 16 O, and the covalent bond formed by 18 O has a longer lifespan than that formed by 16 O and has a stronger binding energy than 16 O.

[0003] In recent years, with the active development in fields such as electric vehicles and energy storage power plants, high energy density and a wide operating temperature range have become the future development direction of lithium-ion batteries. Since the cathode is a core component of a lithium-ion battery, the development of materials that can adapt to high voltage and high temperature conditions is the key to improving the energy density of the battery and expanding the operating temperature range of the battery. However, in the case of mainstream oxide cathode materials, due to high voltage and high temperature working environments, oxygen atoms in the lattice become unstable, escape from the lattice, and are likely to cause the collapse of the structure, which further threatens the safety and electrochemical properties of the battery.

[0004] Currently, the mainstream modification method is zirconium element doping (Tina et al. Structural and electrochemical aspects of LiNi 0.8 Co 0.1 Mn 0.1These include near-surface doping, such as O2 cathode materials doped by various cations, ACS Energy Lett. 4 (2019) 508-516), and boron element doping (Chong et al. Surface reinforcement doping to suppress oxygen release of Li-rich layered oxides, J. Power Sources, Volume 503, 2021, 230048). This modification strategy achieves lattice oxygen stabilization of oxide cathodes under high voltages and temperatures by forming high-energy covalent bonds between oxygen atoms and doping atoms. Furthermore, to improve the thermal stability of oxide cathode materials, modification methods such as the fabrication of core-shell structures (Lee et al., Compositional core-shell design by nickel leaching on the surface of Ni-rich cathode materials for advanced high-energy and safe rechargeable batteries, J. Power Sources, Volume 400, 2018, Pages 87-95) and near-surface coating (Zou et al., Constructing a stable interfacial phase on single-crystalline Ni-rich cathode via chemical reaction with phosphomolybdic acid, Nano Energy, Volume 87, 2021, 106172) have been proposed. While these modification methods have some effectiveness, they still suffer from issues such as uneven modification and insufficient lattice oxygen stability, which affect the cycling stability and safety of batteries.

[0005] In view of the above problems, the present invention innovatively utilizes the isotope effect of oxygen to produce a non-radioactive ion beam with a long half-life. 18By constructing oxide cathode materials using O as the sole oxygen source, the covalent bond energy between the transition metal atoms and lattice oxygen is increased, while the energy barrier for lattice oxygen diffusion is also increased, thereby stabilizing the lattice oxygen in the crystal structure under high voltage and high temperature conditions. This method not only improves the energy density and cycle performance of oxide cathode materials, but also significantly enhances the inherent structural stability of the oxide cathode materials, thereby effectively improving their inherent safety characteristics. Furthermore, this process is characterized by its ease of operation and high compatibility with existing production lines. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention provides a method for producing and using an oxide cathode material constructed with isotopic oxygen to overcome the shortcomings of the prior art. [Means for solving the problem]

[0007] To achieve the above objectives, the present invention adopts the following technical solutions.

[0008] One of the objectives of the present invention is to develop a long half-life, non-radioactive 18 It is produced using O as the only oxygen source, and all lattice oxygen sites in the crystal structure are 18 The goal is to provide an oxide cathode material constructed with oxygen isotopes, dominated by O.

[0009] Preferably, the oxide cathode material is LiCoO2, LiNi x Co y M 1-x-y O2 (M=at least one of Mn and Al, 1≧1-xy≧0, 1≧x≧0, 1≧y≧0), LiMn2O4, xLi2MnO3·(1-x)LiMO2 (M=one or more of Ni, Co, and Mn, 1≧x≧0).

[0010] Another object of the present invention is to provide Transition metal salts and heavy oxygen water H2 required for manufacturing the precursor of the oxide cathode 18 O are used to prepare a transition metal salt solution, and an organic acid and heavy oxygen water H2 18 O are used to prepare a complexing agent. The transition metal salt solution is added to the complexing agent, heated and stirred until a sol-gel is formed. Next, the sol-gel is vacuum dried to form a dried sol-gel, and vacuum ball milled to obtain a precursor, step S1; Step S2 of uniformly mixing the precursor obtained in S1 with a lithium salt to obtain a blend; 18 In an O2 atmosphere, the blend in S2 is heated to a certain temperature, held for a certain period of time for reaction, and when the reaction is completed, 18 Step S3 of obtaining an oxide cathode material constructed with O, including; 18 To provide a manufacturing method of an oxide cathode material constructed with O.

[0011] Preferably, in step S1, the transition metal salt includes transition metal salts having metal nickel ions, cobalt ions, manganese ions, etc. as cations and nitrates, sulfates, etc. as anions, but is not limited thereto, and the transition metal salt used does not have crystal water.

[0012] Preferably, the organic acid used in step S1 is one or more of organic acids such as citric acid, glycolic acid, or glycine, and the oxygen atoms in the organic acid molecule are 18 O atoms.

[0013] Preferably, in step S1, the molar ratio of the total transition metal ions to the organic acid molecules is 1:1.1 - 1.4.

[0014] Preferably, in step S1, the concentration of the transition metal salt solution is 0.01 - 5 mol L -1 And the concentration of the organic acid in the complexing agent is 0.5 - 10 mol L -1 .

[0015] Preferably, in step S1, the heating and stirring are performed at 50 - 80 °C and 150 - 500 rpm.

[0016] Preferably, in step S1, for vacuum drying, the gel is placed in a vacuum oven at 120 to 200 °C and left for 5 to 12 h, and the degree of vacuum in the vacuum oven is 1×10 -1 ~1×10 -5 Pa.

[0017] Preferably, in step S1, for vacuum ball milling, the dried sol-gel after drying is placed in a vacuum ball milling tank and ball milled at 150 to 500 rpm for 1 to 10 h to obtain a precursor with a particle size of 0.8 to 3 μm, and the degree of vacuum in the vacuum ball milling tank is 1×10 -1 ~1×10 -5 Pa.

[0018] Preferably, in step S2, the molar ratio of the precursor to lithium ions in the lithium salt is 1:1.1 to 1.3, and the lithium salt is one or more of lithium hydroxide, lithium carbonate, and lithium acetate in which all oxygen atoms are 18 O atoms.

[0019] Preferably, in step S3, after vacuum suction in the reaction vessel, 18 O2 gas is introduced. Here, 18 the degree of vacuum before introducing O2 gas is controlled to 1×10 -1 ~1×10 -5 Pa, and 18 the flow rate of O2 gas is controlled to 20 to 50 mL min -1 .

[0020] Preferably, in step S3, the temperature is raised to 500 to 950 °C at a heating rate of 2 to 10 °C min -1 and kept warm for 5 to 24 h.

[0021] A further object of the present invention is to provide the use of an oxide cathode material constructed with 18 O in a lithium ion battery and its manufacture.

Advantages of the Invention

[0022] The beneficial effects of the present invention are: Long half-life, non-radioactive 18 The precursor was prepared by the sol-gel method using O as the only oxygen source, and then sintered by solid-phase sintering. 18 In the present invention, an oxide cathode material containing O as the oxygen element is synthesized. 18 O 16 It has two more neutrons than O and its atomic mass is 16 Because the atomic mass of the transition metal is larger than that of O, it increases the covalent bond energy between the transition metal atom and the lattice oxygen while raising the energy barrier for lattice oxygen diffusion. This allows the lattice oxygen in the oxide positive electrode material to be fixed and stabilized in the crystal structure under high voltage and high temperature conditions. Furthermore, it has the advantage of effectively avoiding problems such as oxygen escape from the lattice, which can cause the crystal structure to collapse, shorten the cycle life of the oxide positive electrode material, and deteriorate its safety. This method not only effectively improves the energy density and cycle performance of the oxide positive electrode material, but also significantly improves the inherent structural stability of the oxide positive electrode material, thereby effectively improving the inherent safety characteristics of the oxide positive electrode material. Furthermore, this process is characterized by its simplicity and high compatibility with conventional production processes. [Brief explanation of the drawings]

[0023]

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[0024] For ease of understanding, the technical solutions and embodiments of the present invention will be described more clearly, completely, and in detail below using specific examples and with reference to the drawings. It should be noted that the examples described in the present invention are implemented based on the technical solutions of the present invention and show detailed embodiments and specific operating procedures, but they are only some examples of the present invention, not all examples. The specific embodiments described are limited for the interpretation and explanation of the present invention, and do not limit the present invention. All other examples that can be obtained by those skilled in the art based on the examples of the present invention without creative work fall within the protection scope of the present invention.

[0025] Unless otherwise specified, all experimental methods used in the following examples are conventional methods, and all materials, reagents, etc. used in the examples are commercially available unless otherwise specified.

[0026] The preparation methods of some related substances according to the present invention are as follows.

[0027] Li 18 How OH is produced: 1: Prepare lithium foil and deuterated water in a molar ratio of 1:1.01. 2: Place the lithium foil in a sealed Erlenmeyer flask containing heavy oxygen water, heat and stir, and when the metallic lithium particles in the glass bottle disappear and the heavy oxygen water evaporates and condenses, Li 18 Obtain OH. Li2C 18 How O3 is produced: Li in the reaction flask 18 Excessive C in OH 18 After introducing O2, the Li2C 18 Get O3.

[0028] CH3C 18 O 18 How OLi is made: 1: Ethylene powder and heavy oxygen water are heated and stirred to obtain a heavy oxygen ethanol solution. 2: Copper and 18 Add O2, heat and stir to obtain deoxyacetic acid. 3. Remove the copper, add stoichiometric lithium powder to the deuterium acetic acid solution, and heat and stir at 200-300 rpm and 30-50°C for half an hour. When the metallic lithium particles in the glass bottle become long, the deuterium acetic acid will evaporate and condense, forming CH3C 18 O 18 Get OLi.

[0029] Citric acid (C6H8 18 O7) Manufacturing Method: 1: Anodic oxidation of heavy oxygen water to H2 18 Produces O2. 2: Hydrogen iodide, 1,2-ethylene dibromide, Na 18 OH to give cyclohexene, where Na 18 OH is obtained by reacting sodium powder with deuterated water. 3:H2 18 Cyclohexene is oxidized with O2 and H 18 O 18 OC(CH2)4C 18 O 18 Obtain OH. 4: Chloroacetic acid to Na 18OH to form sodium chloroacetate, which is reacted with KCN to give sodium α-cyanoacetate, followed by alkaline hydrolysis, calcium salt displacement, and acidification to give sodium α-cyanoacetate. 18 O 18 OCCH2 18 O 18 Obtain OH. 5: All oxygen elements 18 O adipic acid and malonic acid react with each other, and C6H8 18 Get O7.

[0030] Glycolic acid (H 18 OCH2C 18 O 18 OH) manufacturing method: 1: CH2 by methane oxidation 18 Manufacture O. 2:CH2 18 O and hydrocyanic acid are reacted at atmospheric pressure at 0-50°C while controlling the pH to 5-6 or 8-9, and the resulting dicyanomethanol is hydrolyzed at pH 3-5. The reaction temperature is controlled above 90°C, and the resulting product is extracted and crystallized. 18 OCH2C 18 O 18 Obtain OH.

[0031] Glycine (NH2CH2C 18 O 18 OH) manufacturing method: 1: CH2 by methane oxidation 18 Manufacture O. 2:CH2 18 Using O, HCN, and NH3 as raw materials, NH2CH2C 18 O 18 OH is produced. The present invention 18 O2 and H2 18 It was purchased from Isotop China, whose website is https: / / isotopechina.com / index.html.

[0032] Example 1: S1. Weigh out nickel sulfate, cobalt sulfate, and manganese sulfate so that the molar ratio of transition metal ions is 8:1:1, and add H2 18 O is used as a solvent with a concentration of 0.01 mol L -1 A transition metal salt solution was prepared. Then, the total transition metal ions and citric acid (C6H8 18 O7) was weighed out so that the molar ratio of H2 18 O with a concentration of 0.5 mol L -1 Next, the transition metal salt solution was added dropwise to the complexing agent at 60°C and stirred at 300 rpm to form a sol-gel, which was then placed in a vacuum oven at 120°C and dried after 12 hours (vacuum degree 1×10 -2 Pa), then placed in a vacuum ball milling tank and ball milled at 150 rpm for 10 h (vacuum degree 1×10 -5 Pa), a precursor with a particle size of approximately 1 μm was obtained. S2. The precursor obtained in S1 and Li 18 OH were weighed in a molar ratio of 1:1.1, mixed uniformly, and placed in a tube furnace. S3. 1×10 -1 After vacuum suction to Pa, 20 mL min -1 At a flow rate of 18 O2 was introduced and the temperature was maintained at 5°C for 5 min. -1 After the reaction was completed, the mixture was slowly cooled to room temperature and the LiNi 0.8 Co 0.1 Mn 0.1 18 Got O2. The obtained LiNi 0.8 Co 0.1 Mn 0.1 18 The SEM spectrum of O2 is shown in Figure 1, and the refined XRD spectrum is shown in Figure 2. 0.8 Co 0.1 Mn 0.1 18O2, carbon black conductive agent, and PVDF binder were mixed in a 90:5:5 ratio with an appropriate amount of NMP as a solvent to prepare a uniform slurry. This slurry was then applied to an aluminum foil, baked, and roll-pressed to obtain a positive electrode plate. This was then assembled with a lithium sheet as a counter electrode to form a CR2032 half cell. The first cycle capacity of the battery was 198.54 mAhg. -1 The 100-cycle capacity retention rate was 92.88% (30°C, 200mA g -1 , 3.0~4.5 V vs. Li + / Li), and the specific cycle characteristics are shown in FIG.

[0033] Example 2: S1. Cobalt nitrate and H2 18 The transition metal salt solution was prepared by weighing out H2 18 O is used as a solvent with a concentration of 1 mol L -1 A transition metal salt solution was prepared. Then, the total transition metal ions and glycolic acid (C2H4 18 Glycolic acid was weighed out so that the molar ratio of H2 to H3 was 1:1.4. 18 O and concentration is 5 mol L -1 Next, the transition metal salt solution was added dropwise to the complexing agent at 50°C and stirred at 500 rpm to form a sol-gel, which was then placed in a vacuum oven at 200°C and dried after 5 hours (vacuum degree 1×10). -1 Pa), then it was placed in a vacuum ball milling tank and ball milled at 300 rpm for 5 h (vacuum degree 1×10 -3 Pa), a precursor with a particle size of approximately 0.8 μm was obtained. S2. The precursor obtained in S1 and Li2C 18 O3 was weighed in a molar ratio of 1:0.6, mixed uniformly, and placed in a tube furnace. S3. 1×10 -5 After vacuum suction to Pa, 35 mL min -1 At a flow rate of 18 O2 was introduced and the temperature was maintained at 5°C for 5 min. -1 After the reaction was completed, the mixture was slowly cooled to room temperature and the LiCo 18 Got O2. The obtained LiCo 18 A slurry of O2, carbon black conductive agent, and PVDF binder was prepared in a ratio of 90:5:5, coated on aluminum foil, baked, and roll-pressed to obtain a positive electrode plate. This was then assembled with a lithium sheet as the counter electrode to form a CR2032 half cell. The first cycle capacity of the battery was 207.64 mAhg. -1 The 100-cycle capacity retention rate was 96.76% (30°C, 200mA g -1 , 3.0-4.6 V vs. Li + / Li).

[0034] Example 3 S1. Manganese sulfate and H2 18 The transition metal salt solution was prepared by weighing out H2 18 O is used as a solvent with a concentration of 5 mol L -1 A transition metal salt solution was prepared. Then, the total transition metal ions and glycine (C2H5N 18 Glycine was weighed out so that the molar ratio of H2 to O2 was 1:1.1. 18 O and concentration is 10 mol L -1 Next, the transition metal salt solution was added dropwise to the complexing agent at 80°C, and the mixture was stirred at 150 rpm to form a sol-gel, which was then placed in a vacuum oven at 150°C and dried after 8 hours (vacuum degree 1×10). -1 Pa), then it was placed in a vacuum ball milling tank and ball milled at 300 rpm for 5 h (vacuum degree 1×10 -5 Pa), a precursor with a particle size of approximately 3 μm was obtained. S2. The precursor obtained in S1 and Li 18 OH were weighed in a molar ratio of 1:1.3, then mixed uniformly and placed in a tube furnace. S3. 1×10 -1 After vacuum suction to Pa, 30 mL min -1 At a flow rate of 18 O2 was introduced and the temperature was maintained at 2°C for 2 min. -1 After the temperature was raised to 950°C at a rate of 100°C, the mixture was kept at the same temperature for 5 hours. After the reaction was completed, the mixture was slowly cooled to room temperature and the LiMn2 18 Got O4. The obtained LiMn2 18 A slurry of O4, carbon black conductive agent, and PVDF binder was prepared in a ratio of 90:6:4. The slurry was applied to aluminum foil, baked, and roll-pressed to obtain a positive electrode plate. A lithium sheet was used as the counter electrode, and these were assembled into a CR2032 half cell. The first cycle capacity of the battery was 138.5 mAhg. -1 The 100-cycle capacity retention rate was 93.78% (55°C, 200mA g -1 , 3.6-4.8 V vs. Li + / Li).

[0035] Example 4 S1. Weigh out nickel sulfate, cobalt sulfate, and manganese sulfate in the molar ratio of transition metal ions, and add H2 18 O is used as a solvent with a concentration of 4 mol L -1 A transition metal salt solution was prepared. Then, the total transition metal ions and citric acid (C6H8 18 O7) was weighed out so that the molar ratio of H2 18 O and concentration is 8 mol L -1 Next, the transition metal salt solution was added dropwise to the complexing agent at 60°C and stirred at 300 rpm to form a sol-gel, which was then placed in a vacuum oven at 500°C and dried after 5 hours (vacuum degree 1×10). -3 Pa), then it was placed in a vacuum ball milling tank and ball milled at 500 rpm for 1 h (vacuum degree 1×10 -1 Pa), a precursor with a particle size of approximately 1.8 μm was obtained. S2. The precursor obtained in S1 and lithium acetate C2H3 18 O2Li was weighed out in a molar ratio of 1:1.2, mixed uniformly, and then placed in a tube furnace. S3. 1×10 -2 After vacuum suction to Pa, 50 mL min -1 At a flow rate of 18 O2 was introduced and the temperature was increased to 10°C for 1 min. -1 After the temperature was raised to 900°C at a rate of 14 hours, the temperature was maintained. After the reaction was completed, the mixture was slowly cooled to room temperature. 1.2 Ni 0.16 Co0.08 Mn 0.56 18 O₂ was obtained. The obtained Li 1.2 Ni 0.16 Co 0.08 Mn 0.56 18 O₂, carbon black conductive agent, and PVDF binder were used to prepare a slurry in a ratio of 90:5:5, which was coated on an aluminum foil, baked, and roll-pressed to obtain a positive electrode plate. Using a lithium sheet as the counter electrode, these were assembled into a CR2032 type half-cell. The initial cycle capacity of the battery was 243.7 mA h g -1 and the 100-cycle capacity retention rate was 92.56% (45 °C, 200 mA g -1 , 3.0 - 4.75 V vs. Li + / Li).

[0036] Comparative Examples 1 - 4 16 Using O as the oxygen source, according to the process parameters of Examples 1 - 4, LiNi 0.8 Co 0.1 Mn 0.1 O₂, LiCoO₂, LiMn₂O₄, and Li 1.2 Ni 0.16 Co 0.08 Mn 0.56 O₂ oxide cathode materials were synthesized. The obtained oxide cathode materials were assembled into a CR2032 type half-cell according to the process parameters of Examples 1 - 4. The test environment and electrochemical parameters of this battery were the same as those of Examples 1 - 4, and the initial cycle capacity and 100-cycle capacity retention rate of the measured batteries are all shown in Table 1. Here, the specific cycle characteristics of the battery in Comparative Example 1 are shown in Figure 4.

[0037]

Table 1

[0038] Comparative Example 5 Taking lithium cobalt oxide (LCO) oxide cathode material as an example, the 16 O inside and outside and 18The four oxide positive electrode materials with different O atom distributions are compared to further reflect the effect of the present invention, which can also be applied to other oxide positive electrode materials described in the present invention. Sample No. 1: Inside and outside 16 O Sample No. 2: Core 16 O, shell is 18 O. Sample No. 3: Core 18 O, shell is 16 O. Sample No. 4: Inside and outside 18 O.

[0039] Model diagrams of the four oxide cathode materials are shown in Figure 5. The manufacturing methods are as follows. Sample No. 1: 18 All ingredients containing O are conventional 16 The samples were synthesized by substituting raw materials with natural abundance of O and employing the manufacturing method described in this invention. Sample No. 2: Sample No. 1 was used as the target for modification. 18 The surface is sintered by plasma sintering in an O atmosphere. 16 Part of O 18 Replace with O, 18 O-rich shell and 16 After many experiments, it was found that the modified sample with the core of O could be completely removed by extending the sintering time, increasing the sintering temperature, or using the high activity plasma sintering technique. 18 It was verified that it was still impossible to obtain sample No. 4, which was composed of O. Sample No. 3: Sample No. 4 was used as the denatured object. 16 Plasma sintering in an O atmosphere produces a surface 18 Part of O 16 Replace with O and 16 O, inside 18 Similarly, after many experiments, it was found that even if the sintering time or temperature was increased, the 18 All O 16 It has been verified that it is impossible to completely replace it with O. Sample No. 4: LiCo of Example 2 18 Use LiCoO2 as Sample No. 4.

[0040] Test Example 1: The four samples showed the following characteristics. Characteristic (1): X-ray diffraction spectra (XRD) and structure refinement were used to study the differences in the crystal structures of the four materials. As shown in Fig. 6, all four different oxide cathode materials maintained an obvious layered structure and had similar crystal structures. The crystal structures were refined for the obtained spectral data, and the unit cell parameters corresponding to the four samples are shown in Table 2. Based on the obtained crystal structure information, in Samples No. 2, No. 3, and No. 4, 16 Part of the O is 18 replaced by 16 O, the c-axis shrinks compared to Sample No. 1 composed of O, and in Sample No. 4 (completely 18 composed of O atoms), the most significant c-axis shrinkage was shown. Usually, the lithium ion transport path of the lithium cobalt oxide cathode is perpendicular to the direction of the c-axis. When the c-axis shrinks, the distance between adjacent ab planes becomes narrower, the lithium ion transport path and diffusion path become narrower, and the electrochemical reaction rate of lithium storage / discharge of the material decreases. Therefore, this modification is considered to have an adverse effect on the improvement of the electrochemical properties of the electrode material. However, the materials of the present invention exhibit better electrochemical properties.

Table 2

[0041] Characteristic (2): In order to further clarify the differences in the microstructure between the four materials, a Raman spectroscopy test was carried out. As shown in Fig. 7, the characteristic spectra of Samples No. 1 and No. 3 are similar, and the characteristic spectra of Samples No. 2 and No. 4 are also similar. When carefully comparing the Raman spectra of Samples No. 1 and No. 1, the E g vibration mode (O-Co-O bending vibration) and A 1gThe intensities of the vibration modes (O-Co stretching vibrations) are shown to be similar. 16 O is 18 not replaced by 18 O, or only a very small part near the surface is g replaced by 1g O (Note: The detection signal depth of the Raman spectrum is 100 nm), the oxide cathode material maintains its original vibration mode. However, in Samples No. 2 and No. 4, the vibration intensity of E 1g (O-Co-O bending vibration) changes from being close to the vibration intensity of A g (O-Co stretching vibration) to half of the vibration intensity of A 1g (O-Co stretching vibration). Also, the intensities of the two vibration modes, E 16 (O-Co-O bending vibration) and A 18 (O-Co stretching vibration) in these spectra are much lower than those of Samples No. 1 and No. 3. The above results 18 show that when

[0042] Feature (3): Table 3 shows the results of testing the electronic conductivities of the above four materials and a commercially available lithium cobalt oxide cathode material.

Table 3

[0043] Feature (4): Investigate the dynamic characteristics of lithium ion diffusion in four materials. The galvanostatic intermittent titration method is widely used as a method for studying the dynamics of lithium ion transport in electrode materials. First, a plurality of galvanostatic intermittent titration studies were carried out on the four cathode materials, and the lithium ion diffusion coefficients corresponding to the four cathode materials were carefully checked to confirm that the obtained data could be effectively reproduced. As shown in Figure 8, from the change in the lithium ion diffusion coefficients of the four cathode materials, 16 it was found that No. 1, No. 2, and No. 3 containing O atoms all show relatively close lithium ion diffusion coefficients. However, surprisingly, 18 When O is 16 completely replaced by O, the lithium ion diffusion coefficient of Sample No. 4 was significantly improved, especially in the voltage platform range where the material undergoes redox reactions, and the lithium ion diffusion flux became higher. Therefore, it has better dynamic characteristics of lithium ion transport. When combined with Feature (1), since the lattice constant along the c-axis direction of Sample No. 4 is the smallest, it is considered that the lithium ion diffusion coefficient of Sample No. 4 is the smallest, but the result of Feature (4) is completely opposite to this, so it is unpredictable.

[0044] Test Example 2: The electrochemical characteristics of the four sample electrode materials were investigated as follows. Assemble the four materials into a battery according to the battery of Example 2, and investigate the electrochemical characteristics based on that battery. (1) The electrochemical behavior of the four electrode materials was investigated by cyclic voltammetry at a scan rate of 0.1 mV / s and a scan range of 3.0 V to 4.8 V. As shown in Figure 9, Sample No. 1 had the poorest electrochemical reaction activity, 16 Part of O 18 The other two materials (Samples No. 2 and No. 3) in which O was substituted showed slight improvements. In contrast, Sample No. 4 exhibited a stronger redox peak current density and a sharper redox peak, indicating that Sample No. 4, an oxide positive electrode material of the present invention, has stronger redox activity than the other three materials and is more suitable as a positive electrode material for lithium-ion batteries.

[0045] (2) The applicant compared the rate characteristics of batteries using four samples at current densities of 20, 100, and 200 mA / g and voltages ranging from 3.0 V to 4.6 V. As shown in Figure 10, the discharge specific capacities of oxide cathode material samples No. 1, No. 2, and No. 3 at various rates were similar, and some capacity loss occurred after multiple cycles at high rates. On the other hand, the discharge specific capacity of oxide cathode material sample No. 4 at various rates was higher than that of samples No. 1, No. 2, and No. 3, and the reversible capacity was stable after multiple cycles at various rates, with no obvious loss. The above results suggest that the use of a high-performance oxide cathode material is essential when constructing an oxide cathode material. 16 O 18 It has been fully demonstrated that only a complete substitution with O can effectively improve the rate and cycle properties of the material, which is contrary to the relevant results and laws of electronic conductivity and is unpredictable.

[0046] (3) The applicant tested the cycle characteristics of the four samples at a current density of 200 mA / g and a voltage range of 3.0 V to 4.6 V. As shown in FIG. 11, the oxide cathode 18 O 16When O is partially replaced, regardless of whether the replaced part is the core or the shell of the cathode material, Samples No. 2 and No. 3 are the same as Sample No. 1, and under high cut-off voltage conditions, long-term stable cycling cannot be achieved. However, the oxide cathode material Sample No. 4 of the present invention exhibits very good cycle characteristics.

[0047] In summary, the oxide cathode material Sample No. 4 described in the present invention shows a lattice arrangement structure that is disadvantageous for lithium ion transport and has a lower electron conductivity, but exhibits excellent electrochemical reaction activity, excellent rate characteristics, and enhanced cycle stability.

[0048] From the above results, it was found that the advantage of the present invention lies in synthesizing the oxide cathode material using non-radioactive 18 O as the only oxygen source. On the one hand, it increases the binding energy of the covalent bond between the transition metal atom and the lattice oxygen. On the other hand, it increases the energy barrier for lattice oxygen diffusion, thereby enabling the lattice oxygen in the oxide cathode material to be fixed under high voltage and high temperature conditions, and avoiding the escape of oxygen elements from the lattice and the collapse of the crystal structure. This method not only improves the energy density and cycle characteristics of the oxide cathode material, but also greatly improves the inherent structural stability of the oxide cathode material, thereby effectively improving the inherent safety characteristics of the oxide cathode material. Furthermore, this process also has the characteristics of simple operation and high compatibility with existing production lines.

[0049] Although the present invention has been described in detail above by general description, specific embodiments and experiments, the present invention is not limited in any form. Based on the present invention, some modifications or improvements are possible, which are obvious to those skilled in the art. Therefore, all modifications or improvements made without departing from the spirit of the present invention belong to the scope of protection patented by the present invention.

Claims

1. １８ It is manufactured using O as the only oxygen source, and all lattice oxygen sites in its crystal structure are １８ occupied by O, and it is an oxide cathode material constructed of isotope oxygen, characterized by this.

2. LiCoO ２ 、LiNi ｘ Co ｙ M １－ｘ－ｙ O ２ (M = at least one of Mn and Al, 1 ≥ 1 - x - y ≥ 0, 1 ≥ x ≥ 0, 1 ≥ y ≥ 0), LiMnO ２ O ４ 、xLi ２ MnO ３ ・(1 - x)LiMO ２ (M = one or more elements among Ni, Co, and Mn, 1 ≥ x ≥ 0), and the oxide cathode material constructed of isotope oxygen according to claim 1, characterized by containing one or more kinds satisfying the structure.

3. The transition metal salt and heavy oxygen water H required to produce the precursor of the oxide cathode ２ １８ are used to prepare a transition metal salt solution, and an organic acid and heavy oxygen water H ２ １８ O are used to prepare a complexing agent. The transition metal salt solution is added to the complexing agent, heated and stirred until a sol-gel is formed. Then, the sol-gel is vacuum dried to form a dried sol-gel, which is vacuum ball milled to obtain a precursor in step S1 Step S2 of uniformly mixing the precursor obtained in S1 with a lithium salt to obtain a blend １８ O ２ In an atmosphere, the blend in S2 is heated to an elevated temperature, held for a certain period of time for reaction, and when the reaction is completed, １８ Step S3 of obtaining an oxide cathode material constructed with O, and a method for manufacturing an oxide cathode material constructed with isotopic oxygen according to claim 1 or 2, characterized by comprising the same.

4. In step S1, the transition metal salt includes a transition metal salt having at least one of nickel ions, cobalt ions, and manganese ions as cations and at least one of nitrates and sulfates as anions, and the transition metal salt used has no crystal water, and the concentration of the prepared transition metal salt solution is 0.01 to 5 mol / L －１ The method for manufacturing an oxide cathode material constructed with isotope oxygen according to claim 3, characterized in that it is as described above.

5. The organic acid used in step S1 is one or more of citric acid, glycolic acid, and glycine, and the oxygen atoms in the organic acid molecule are １８ O atoms, and the concentration of the organic acid in the prepared complexing agent is 0.5 to 10 mol L －１ The method for producing an oxide cathode material constructed of isotope oxygen according to claim 3, characterized in that it is as described above.

6. In step S1, the molar ratio of the total transition metal ions to the organic acid molecules is 1:1.1 to 1.4, and the method for manufacturing an oxide cathode material constructed with isotope oxygen according to claim 3, characterized in that.

7. In step S1, the heating and stirring are performed at 50 to 80°C and 150 to 500 rpm, and the method for manufacturing an oxide cathode material constructed with isotope oxygen according to claim 3, characterized in that.

8. In step S2, the molar ratio of the precursor to the lithium ions in the lithium salt is 1:1.1 to 1.3, and the lithium salt has all oxygen atoms １８ The method for producing an oxide cathode material constructed of isotope oxygen according to claim 3, characterized in that it is one or more of lithium hydroxide, lithium carbonate, and lithium acetate in which all oxygen atoms are

9. In step S3, after evacuating the inside of the tubular furnace, １８ O ２ gas is introduced. Here, １８ O ２ the degree of vacuum before introducing the －１ O －５ gas is controlled to be 1×10 １８ O ２ to 1×10 －１ Pa, and the flow rate of the 2 to 10 °C min －１ The method for producing an oxide cathode material constructed of isotope oxygen according to claim 3, characterized in that the temperature is raised to 500 to 950 °C at a heating rate of and held for 5 to 24 h.

10. Use of the oxide cathode material constructed with isotope oxygen according to claim 1 or 2 in a lithium-ion battery and its manufacture

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