A triangular bipyramidal vacancy layered oxide and its application in lithium batteries

Abstract

This invention belongs to the field of lithium-ion battery technology, and discloses a triangular bipyramidal vacancy layered oxide and its application in lithium batteries. The preparation method of this triangular bipyramidal vacancy layered oxide involves uniformly mixing a sodium source, a cobalt source, and / or raw materials containing element M, followed by calcination to obtain Na. x Co y M 1‑y O2, where 0.50≤x≤1.00, 0.50≤y≤1.00; Na x Co y M 1‑y O2 is mixed with a first lithium source and reacted at 60~260℃ to obtain a lithium intercalation intermediate; the lithium intercalation intermediate and a second lithium source are mixed evenly and the resulting mixture is subjected to external field treatment to obtain a triangular bipyramidal vacancy layered oxide. This invention effectively solves the technical problem in the prior art that the energy density, rate performance and cycle stability of lithium-rich manganese-based cathode materials under high voltage cannot be simultaneously achieved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology and relates to a triangular bipyramidal vacancy layered oxide and its application in lithium batteries. Background Technology

[0002] As a key component of lithium-ion batteries, the performance improvement and technological innovation of cathode materials not only have a decisive impact on the battery's performance indicators, but are also a crucial breakthrough in overcoming the bottlenecks in lithium-ion battery development and propelling the industry to new heights. In lithium-ion battery cathode materials, crystal structure, as an intrinsic property, directly defines the theoretical performance upper limit of the cathode material. Currently, O3-structured layered oxide cathode materials, which are widely studied, belong to the thermodynamically stable phase. Among O3-phase layered materials, lithium-rich manganese-based cathode materials exhibit extremely high energy density, but their rate performance is poor and voltage decay is severe. High-nickel materials are prone to phase transitions and lattice distortions under high delithiation states, which obstructs lithium-ion diffusion paths and makes it difficult to maintain high energy density output during high-current charge-discharge cycles. Lithium cobalt oxide undergoes a harmful O3-to-O1 phase transition under high voltage, leading to rapid capacity decay. The crystal structures of these O3-structured layered oxides all exhibit an ABCABC oxygen stacking arrangement, with LiO6 octahedra and TMO6 octahedra sharing edges. The diffusion of a single lithium ion to an adjacent lithium ion site is usually limited to interstitial tetrahedral vacancies, resulting in relatively high lithium-ion diffusion barriers and relatively poor diffusion kinetics. Consequently, although these materials possess high energy density at high voltages, they struggle to exhibit superior rate performance and cycle stability. Therefore, exploring cathode materials with larger interstitial vacancies has become a key research direction for improving lithium-ion battery performance and overcoming industry bottlenecks. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a triangular bipyramidal vacancy layered oxide and its application in lithium batteries, thereby solving the technical problem that existing lithium-rich manganese-based cathode materials cannot simultaneously achieve high energy density, high rate performance, and good cycle stability under high voltage.

[0004] This invention is achieved through the following technical solution: A method for preparing a trigonal bipyramidal vacancy layered oxide includes the following steps: S1: After uniformly mixing sodium source, cobalt source and / or raw materials containing element M, calcination is performed to obtain the layered oxide Na for P2 type sodium-ion batteries. x Co y M 1-y O2, where 0.50≤x≤1.00, 0.50≤y≤1.00; S2: The P2 type sodium-ion battery layered oxide Nax Co y M 1-y O2 is mixed with the first lithium source and reacted at 60~260℃ to obtain a lithium intercalation intermediate; S3: The lithium intercalation intermediate is mixed uniformly with a second lithium source, and the resulting mixture is subjected to external field treatment, including electromagnetic field treatment, thermal field treatment, or ultrasonic treatment, to obtain a triangular bipyramidal vacancy layered oxide LiCo. y M 1-y O2, where 0.50≤y≤1.00.

[0005] Preferably, in step S1, the calcination process specifically involves: heating to 400-600℃ at a heating rate of 2-10℃ / min, pre-calcining for 1-8 hours, and then calcining at 700-900℃ for 2-20 hours to complete the calcination process.

[0006] Preferably, in step S1, element M is at least one selected from potassium, aluminum, beryllium, boron, fluorine, magnesium, calcium, strontium, scandium, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, tantalum, tungsten, rhenium, osmium, iridium, and platinum.

[0007] Preferably, in step S2, the lithium ions in the first lithium source react with the layered oxide Na of the P2 type sodium ion battery. x Co y M 1-y The molar ratio of sodium ions in O2 is (1.0~15):1.

[0008] Preferably, in step S2, the layered oxide Na of the P2 type sodium-ion battery is formed by solid-phase method, liquid-phase method, and hydrothermal method. x Co y M 1-y O2 reacts with the first lithium source to prepare a lithium intercalation intermediate.

[0009] Preferably, in step S3, when the external field treatment is electromagnetic field treatment, the output power of the electromagnetic field is 500~2000W; when the external field treatment is thermal field treatment, the temperature of the thermal field is 90~200℃; and when the external field treatment is ultrasonic field treatment, the ultrasonic frequency is 25~150 kHz.

[0010] Preferably, in step S3, the time for the field treatment is 1 to 300 minutes.

[0011] Preferably, in step S3, the molar ratio of lithium ions in the second lithium source to cobalt ions in the lithium intercalation intermediate is (0.2~1):1.

[0012] A trigonal bipyramidal vacancy layered oxide was prepared by the method described above.

[0013] The above-mentioned application of a triangular bipyramidal vacancy layered oxide in lithium-ion batteries.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a triangular bipyramidal vacancy layered oxide, its preparation method, and its application. The method first synthesizes a sodium-ion layered oxide with a P2-type structure through solid-state calcination at high temperature. This process is fundamental to the formation of the layered structure and is crucial for the subsequent construction of the triangular bipyramidal structure. Next, within a temperature range of 60–260°C, lithium ions and sodium ions exhibit certain mobility. Due to the difference in chemical potential, lithium ions diffuse towards the sites where sodium ions are located and gradually replace sodium ions in the interlayer positions of the layered structure, forming a lithium-intercalation intermediate. This prepares for the formation of the final target product. This step is key to introducing lithium ions and adjusting the layered structure, and has a significant impact on the formation of the triangular bipyramidal structure. Finally, an external field-assisted lithiation strategy is employed, where the external field... The treatment methods include electromagnetic field treatment, thermal field treatment, or ultrasonic treatment. These methods utilize external fields to facilitate the more efficient entry of lithium ions into structural vacancies, further adjusting the material's structure and properties to ultimately obtain high-purity, high-performance trigonal bipyramidal vacancy layered oxides. Specifically, electromagnetic fields can provide lithium ions with additional energy, enhancing their diffusion ability; increasing temperature, i.e., providing a thermal field, increases the thermal motion of atoms. Under the influence of a thermal field, atomic vibrations intensify, and the local crystal structure becomes "loose," making it easier for lithium ions to diffuse and migrate within the structure. Furthermore, ultrasonic waves propagating in the material generate cavitation effects and mechanical vibrations. These conditions can break down local structures that hinder lithium ion migration, opening new diffusion pathways for lithium ions. Therefore, external field assistance allows lithium ions to more easily approach sodium ion sites, facilitating ion exchange, improving product purity, and effectively solving the problem of difficult pure-phase preparation of metastable layered oxides due to low synthesis temperatures. The layered oxide prepared by this invention possesses a unique triangular bipyramidal vacancy structure. This structure provides a smoother migration path for the reversible insertion and extraction of lithium ions, facilitating rapid lithium ion transport and thus improving the high-rate performance of the material. Testing shows that this cathode material exhibits excellent performance at high voltages. Within a voltage range of 3.0–4.65 V, the first-cycle discharge energy density at 1 C is greater than 1000 Wh / kg, and at 10 C, the first-cycle discharge energy density is greater than 900 Wh / kg. Within a voltage range of 2.0–4.8 V, the capacity retention rate after 50 cycles at 1 C is greater than 90%. This effectively demonstrates that the triangular bipyramidal vacancy layered oxide prepared by this invention possesses high energy density, high-rate performance, and good cycle stability at high voltages.

[0015] Furthermore, in step S1, the calcination process specifically involves: heating to 400-600℃ at a heating rate of 2-10℃ / min for 1-8 hours of pre-calcination, followed by calcination at 700-900℃ for 2-20 hours to complete the calcination process. This step is fundamental to the formation of the layered structure and is crucial for the subsequent formation of the triangular bipyramidal structure. The calcination temperature and time directly affect the crystal structure and properties of the product. By optimizing the calcination process, the pre-calcination stage generates a uniform mixed oxide through a low-temperature reaction, providing a "template" for the growth of the P2-type layered structure in the high-temperature stage. Direct high-temperature calcination can lead to disordered structures or impurities due to excessively rapid reaction rates, hindering the regular arrangement of triangular bipyramidal vacancies. Simultaneously, low-temperature pre-calcination prevents excessive gas escape, abnormal grain growth, or structural collapse caused by rapid reactions at high temperatures. Then, at high temperatures, the pre-calcined mixed oxides undergo solid-state reactions to generate a P2-type layered structure (space group P63mmc). At the same time, atoms diffuse and rearrange to form ordered transition metal layers (Co / MO layers) and sodium layers, repairing lattice defects introduced during the pre-calcination stage. Grain size and defect density can be adjusted by controlling the holding time, optimizing lithium-ion diffusion channels. Furthermore, high temperatures facilitate partial lithium-ion intercalation, inducing oxygen atoms in the transition metal layer to rearrange, forming a triangular bipyramidal coordination environment that provides the core framework for the triangular bipyramidal structure. Therefore, through two-step calcination control, the generation and repair of defects can be controlled, precisely regulating the material structure.

[0016] Furthermore, in step S1, element M is at least one of potassium, aluminum, beryllium, boron, fluorine, magnesium, calcium, strontium, scandium, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, tantalum, tungsten, rhenium, osmium, iridium, and platinum. These elements M all have suitable ionic radii, charge numbers, and chemical stability, and can enter the lattice of the cathode material without destroying the main structure. Instead, they play a role in stabilizing the lattice, strengthening MO bonds, suppressing side reactions, and improving cycle and thermal stability.

[0017] Furthermore, in step S2, lithium ions in the first lithium source react with the layered oxide Na of the P2 type sodium ion battery. x Co y M 1-y The molar ratio of sodium ions in O2 is (1.0~15):1. A suitable molar ratio is the key to achieving effective sodium-lithium ion exchange. It can ensure that lithium ions fully replace sodium ions during low-temperature ion exchange, forming a structurally stable and high-performance lithium intercalation intermediate. At the same time, the lithium ion concentration can make it uniformly intercalated into the layered structure, inducing the rearrangement of oxygen atoms in the transition metal layer, which is conducive to the construction of a trigonal bipyramidal coordination environment.

[0018] Furthermore, in step S3, when the external field treatment is electromagnetic field treatment, the output power of the electromagnetic field is 500~2000W; when the external field treatment is thermal field treatment, the temperature of the thermal field is 90~200 ℃; when the external field treatment is ultrasonic field treatment, the ultrasonic frequency is 25~150 kHz. For electromagnetic field treatment, a suitable output power ensures that the electromagnetic field has an effective effect on lithium-ion migration, promoting lithium-ion entry into structural vacancies; the temperature range of thermal field treatment ensures that while promoting lithium-ion diffusion, it avoids damage to the material structure due to excessive temperature; the frequency range of ultrasonic field treatment can generate ultrasonic waves of appropriate intensity, utilizing their cavitation effect and mechanical vibration to promote lithium-ion diffusion and optimize the material structure. Precise control of these parameters helps to improve the effectiveness of the external field-assisted lithiation strategy, effectively improving the purity and structural stability of the material.

[0019] Furthermore, in step S3, the external field treatment time is 1~300 min. An appropriate external field treatment time is crucial for the effective entry of lithium ions into structural vacancies. If the time is too short, lithium ions cannot fully enter the vacancies, resulting in impurity phases in the material and poor structural stability; if the time is too long, excessive treatment will have an adverse effect on the material structure.

[0020] Furthermore, in step S3, the molar ratio of lithium ions in the second lithium source to cobalt ions in the lithium intercalation intermediate is (0.2~1):1. A suitable molar ratio ensures that lithium ions fully enter the structural vacancies during the external field-assisted lithiation process, further optimizing the crystal structure and electrochemical performance of the material. If the molar ratio is inappropriate, it will lead to insufficient or excessive lithium ion intercalation, affecting the purity of the product, and consequently affecting the energy density, rate performance, and cycle stability of the cathode material under high voltage. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The layered oxide Na for P2 type sodium-ion batteries prepared in Example 1 of this invention 0.7 XRD pattern of CoO2; Figure 2 This is a schematic diagram of the structure of the triangular bipyramidal vacancy layered oxide obtained in Example 1 of the present invention; Figure 3 The XRD pattern of the triangular bipyramidal vacancy layered oxide LiCoO2 (represented as TBV-LiCoO2 in the figure) prepared in Example 1 of the present invention is shown in the refined XRD pattern. Figure 4 The layered oxide Na for P2 type sodium-ion batteries prepared in Example 2 of this invention 0.5 Co 0.99 Al 0.01 Morphological diagram of O2; Figure 5 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 2 of this invention 0.99 Al 0.01 O2 (represented in the diagram as TBV-LiCo) 0.99 Al 0.01 O2) First charge-discharge curves at a voltage range of 3.0~4.7 V and 1 C; Figure 6 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 3 of this invention 0.96 Mn 0.04 O2 (represented in the figure as TBV-LiCo) 0.96 Mn 0.04 Scanning electron microscope image of O2; Figure 7 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 3 of this invention 0.96 Mn 0.04 O2 (represented in the figure as TBV-LiCo) 0.96 Mn 0.04 O2) First charge-discharge curves at a voltage range of 3.0~4.65 V and a voltage of 0.5 C; Figure 8 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 4 of this invention 0.5 Mn 0.5 O2 (represented in the figure as TBV-LiCo) 0.5 Mn 0.5 Cycling performance of O2 in the voltage range of 2.0~4.8 V and 1 C; Figure 9 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 5 of this invention 0.99 Ni 0.01 O2 (represented in the figure as TBV-LiCo) 0.99 Ni 0.01 EDS energy spectrum of O2; Figure 10 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 5 of this invention 0.99 Ni 0.01 O2 (represented in the figure as TBV-LiCo) 0.99 Ni 0.01 Cycling performance of O2 in the voltage range of 3.0~4.55 V and 0.5 C; Figure 11 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 6 of this invention 0.99 Y 0.01 O2 (represented in the diagram as TBV-LiCo) 0.99 Y 0.01 O2) Rate performance in the voltage range of 3.0~4.6 V; Figure 12 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 7 of this invention 0.99 V 0.01 O2 (represented in the diagram as TBV-LiCo) 0.99 V 0.01 The energy density variation of O2 in the voltage range of 3.0~4.65 V and 1 C; Figure 13 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 8 of this invention 0.7 Mn 0.3 O2 (represented in the figure as TBV-LiCo) 0.7 Mn 0.3 Charge-discharge curves of O2 at a voltage range of 2.0~4.8 V and 1 C; Figure 14 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 9 of this invention 0.99 Cu 0.01 O2 (represented in the figure as TBV-LiCo) 0.99 Cu 0.01 O2) First charge-discharge curves at a voltage range of 3.0~4.6 V and a voltage of 0.5 C; Figure 15 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 10 of this invention 0.98 Mg 0.02 O2 (represented in the figure as TBV-LiCo) 0.98 Mg 0.02 Energy density and operating voltage variation of O2 in the voltage range of 3.0~4.65 V and 10 C; Figure 16 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 11 of this invention 0.98 Mn 0.01 Ru 0.01 O2 (represented in the diagram as TBV-LiCo) 0.98 Mn 0.01 Ru 0.01 O2) First charge-discharge curves at a voltage range of 3.0~4.55 V and 1 C; Figure 17The triangular bipyramidal vacancy layered oxide LiCo prepared in Example 12 of this invention has triangular bipyramidal vacancy sites. 0.9 Mn 0.1 O2 (represented in the figure as TBV-LiCo) 0.9 Mn 0.1 Charge-discharge curves of O2 at a voltage range of 2.0~4.8 V and 1 C; Figure 18 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 12 of this invention 0.9 Mn 0.1 O2 (represented in the figure as TBV-LiCo) 0.9 Mn 0.1 Cyclic performance of O2 in the voltage range of 3.0~4.65 V and 1 C. Detailed Implementation

[0023] This invention provides a layered oxide cathode material, specifically, the layered oxide cathode material has a structure with triangular bipyramid vacancies (TBV), and its preparation method includes the following steps: Sodium-containing layered oxide Na was synthesized by high-temperature solid-state calcination. x Co y M 1-y O2 (where M is a substituent element 0.50≤x≤1.00, 0.50≤y≤1.00); then it is uniformly mixed with a lithium source and subjected to low-temperature ion exchange treatment through multiple paths. The product is washed, filtered, and dried to obtain a lithium intercalation intermediate. Then, the lithium intercalation intermediate is mixed with a lithium source, and an external field is applied to obtain the triangular bipyramidal vacancy layered oxide LiCo. y M 1-y O2, 0.50≤y≤1.00.

[0024] Specifically, the above method includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na x Co y M 1-y The sodium source, cobalt source, and / or raw materials containing element M are weighed and uniformly mixed. The mixture is heated to 400-600℃ at a heating rate of 2-10℃ / min for 1-8 h of pre-calcination, followed by calcination at 700-900℃ for 2-20 h. After calcination, the mixture is allowed to cool naturally to room temperature to obtain the P2 type sodium-ion battery layered oxide Na. x Co y M 1-y O2, 0.50≤x≤1.00, 0.50≤y≤1.00; The sodium source includes at least one of sodium carbonate (Na2CO3), sodium bicarbonate (NaHCO3), sodium hydroxide (NaOH), sodium oxide (Na2O), sodium peroxide (Na2O2), sodium chloride (NaCl), sodium nitrate (NaNO3), sodium oxalate (Na2C2O4), sodium acetate (CH3COONa), and sodium sulfate (Na2SO4). The cobalt source includes at least one of cobalt tetroxide (Co3O4), cobalt trioxide (Co2O3), cobalt monoxide (CoO), cobalt carbonate (CoCO3), cobalt hydroxide (Co(OH)2), cobalt hydroxyoxide (CoOOH), cobalt chloride (CoCl2), cobalt nitrate (Co(NO3)2), cobalt oxalate (CoC2O4), cobalt acetate (Co(CH3COO)2), and cobalt sulfate (CoSO4).

[0025] Wherein, the element M is at least one selected from potassium (K), aluminum (Al), beryllium (Be), boron (B), fluorine (F), magnesium (Mg), calcium (Ca), strontium (Sr), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), and platinum (Pt); All of these elements M have suitable ionic radii, charge numbers, and chemical stability, enabling them to enter the cathode material lattice without disrupting the main structure. Instead, they play a role in stabilizing the lattice, strengthening MO bonds, suppressing side reactions, and improving cycle and thermal stability.

[0026] The raw material for element M is at least one of the following: oxide, hydroxide, chloride, carbonate, sulfate, oxalate, nitrate, or acetate of element M.

[0027] S2: Li + / Na + Ion exchange The P2 type sodium-ion battery layered oxide Na x Co y M 1-y O2 is mixed with the first lithium source and reacted at 60~260℃ to exchange sodium ions with lithium ions, thus obtaining a lithium intercalation intermediate. In this step, the exchange of lithium ions and sodium ions can be achieved through multiple pathways, including solid-phase methods, liquid-phase methods, and hydrothermal methods.

[0028] Specifically, the solid-state method includes: The P2 type sodium-ion battery layered oxide Na x Co y M 1-y O2 and the first lithium source are ball-milled and mixed evenly according to a certain Li / Na molar ratio. The mixture is then spread evenly in a ceramic boat and placed in an oven or muffle furnace. Solid-phase ion exchange treatment is carried out at a reaction temperature of 150~260℃ for 1~20 h. After washing, filtration and drying, the lithium intercalation intermediate is obtained. Specifically, the liquid phase method is as follows: The P2 type sodium-ion battery layered oxide Na x Co y M 1-y O2 is uniformly dispersed in a first lithium source solution according to a certain Li / Na molar ratio. The temperature is raised to 60~260℃, and the reaction is carried out for 0.5~15 h. After washing, filtration and drying, a lithium intercalation intermediate is obtained. The solvent of the first lithium source solution is water or ethanol, and deionized water is preferred. The P2 type sodium-ion battery layered oxide Na x Co y M 1-y The ratio of O2 to the first lithium source solution is 1 g:(5~250) mL, and the concentration of the first lithium source solution is 2 mol / L; Specifically, the hydrothermal method includes: The P2 type sodium-ion battery layered oxide Na was stirred magnetically. x Co y M 1-y O2 is uniformly dispersed in a first lithium source solution according to a certain Li / Na molar ratio. The mixed solution is then placed in a high-pressure reactor and heated to 100-220°C for 1-10 hours. After the reaction, the reactor is allowed to cool naturally to room temperature before filtration, washing, and drying to obtain the lithium intercalation intermediate. The solvent for the lithium source solution is water or ethanol, preferably deionized water. The P2 type sodium-ion battery layered oxide Na... x Co y M 1-y The ratio of O2 to the first lithium source solution is 1 g:(5~250) mL, and the concentration of the first lithium source solution is 2 mol / L; The first lithium source includes a lithium salt monomer or a eutectic lithium salt system; The lithium salt monomer includes one of lithium nitrate (LiNO3), lithium chloride (LiCl), lithium hydroxide monohydrate (LiOH∙H2O), lithium oxide (Li2O), lithium peroxide (Li2O2), lithium carbonate (Li2CO3), lithium fluoride (LiF), lithium bromide (LiBr), lithium perchlorate (LiClO4), lithium acetate (LiCH3COO), and lithium oxalate (Li2C2O4); The eutectic lithium salt system includes a eutectic lithium salt system composed of alkali metal salts; specifically, the eutectic lithium salt system includes a eutectic lithium salt system composed of multiple lithium salt monomers or a eutectic lithium salt system composed of other alkali metal salts and lithium salt monomers. The eutectic lithium salt system composed of various lithium salt monomers includes Li2CO3-LiOH, LiNO3-LiOH, LiCl-LiF, LiCl-LiNO3, LiCl-LiF-LiBr or LiNO3-LiOH-LiClO4; Other eutectic lithium salt systems composed of alkali metal salts and lithium salt monomers include eutectic lithium salt systems composed of sodium or potassium salts and lithium salt monomers, wherein the sodium salt is sodium carbonate (Na2CO3), sodium chloride (NaCl) or sodium nitrate (NaNO3), and the potassium salt is potassium carbonate (K2CO3), potassium chloride (KCl) or potassium nitrate (KNO3).

[0029] In a further preferred embodiment, the lithium ions in the first lithium source react with the layered oxide Na of the P2 type sodium ion battery. x Co y M 1-y The molar ratio of sodium ions in O2 is (1.0~15):1.

[0030] S3: Field-enhanced lithiation The lithium intercalation intermediate and the second lithium source are mixed uniformly at a certain Li / Co molar ratio, and the resulting mixture is subjected to external field treatment, including electromagnetic field, thermal field, or ultrasonic treatment, for a duration of 1-300 min, to obtain the trigonal bipyramidal vacancy layered oxide LiCo. y M 1-y O2, 0.50≤y≤1.00.

[0031] The second lithium source includes at least one of lithium nitrate (LiNO3), lithium chloride (LiCl), lithium hydroxide monohydrate (LiOH∙H2O), lithium oxide (Li2O), lithium peroxide (Li2O2), lithium carbonate (Li2CO3), lithium fluoride (LiF), lithium bromide (LiBr), lithium perchlorate (LiClO4), lithium acetate (LiCH3COO), and lithium oxalate (Li2C2O4); The output power of the electromagnetic field is 500~2000 W, the temperature of the thermal field is 90~200℃, and the ultrasonic frequency during ultrasonic treatment is 25~150 kHz.

[0032] Furthermore, the molar ratio of lithium ions in the second lithium source to cobalt ions in the lithium intercalation intermediate is (0.2~1):1.

[0033] This invention also discloses a trigonal bipyramidal vacancy layered oxide prepared by the above method. This cathode material exhibits thermodynamic metastable characteristics and has a space group of [missing information]. P6 3 mc The material comprises micron-sized particles with triangular bipyramidal vacancies, ranging in size from 1 to 20 μm, and the particle size is controllable. These unique triangular bipyramidal vacancies provide larger lithium-ion diffusion channels, lower lithium-ion diffusion barriers, and stronger structural stability, thereby endowing layered oxides with superior rate performance, energy density output, and reversible capacity retention. This effectively solves the structural intrinsic and output performance bottlenecks caused by the small interstitial vacancies and poor lithium-ion diffusion kinetics in existing O3-structured layered oxide crystal structures. Furthermore, the preparation method in this invention effectively solves the problems of numerous associated impurities and poor performance in metastable phase materials in existing technologies.

[0034] The method for preparing triangular bipyramidal vacancy layered oxides disclosed in this invention first synthesizes sodium-containing layered oxides through high-temperature solid-state calcination. This sodium-containing layered oxide is then uniformly mixed with a lithium source and subjected to low-temperature ion exchange treatment via multiple pathways, including solid-state, liquid-state, and solvothermal processes. The product is washed, filtered, and dried to obtain a lithium intercalation intermediate. Finally, an external field-assisted lithiation strategy is used to prepare triangular bipyramidal vacancy layered oxides (LiCo). y M 1-y O2. High-temperature solid-state calcination for preparing sodium-containing layered oxide intermediates can significantly improve the tap density of the material. The process is simple, mature, and has high equipment compatibility and scalability. Low-temperature solid-state ion exchange pathways can achieve solid-state Li under low-temperature and low-energy conditions through temperature control. + / Na + Ion diffusion yields layered oxides with high crystallinity, uniform grain size, and high tap density; the liquid-phase ion exchange pathway is based on the solution environment to achieve Li + / Na +Ion concentration gradient driven ion diffusion offers highly controllable ion diffusion kinetics, mild and homogeneous reaction conditions, wide applicability, and effective preservation of intermediate morphology. The solvothermal ion exchange pathway creates high-temperature, high-pressure reaction conditions in a closed autoclave, effectively promoting crystal growth and leveraging the high diffusivity of the solvent to achieve the dual advantages of solid-phase crystallinity and liquid-phase reactivity. All three pathways can achieve controllable ion exchange at relatively low temperatures. External field assistance allows lithium ions to effectively enter vacancies in the structure; that is, external field-assisted lithiation can effectively solve the technical problem of difficult pure-phase preparation of metastable layered oxides due to relatively low synthesis temperatures (≤300℃).

[0035] The method for preparing triangular bipyramidal vacancy layered oxides disclosed in this invention offers multiple options, has a simple process path, mild conditions, and produces triangular bipyramidal vacancy layered oxides with uniform particle distribution, controllable particle size, and good batch uniformity.

[0036] The triangular bipyramidal vacancy layered oxide prepared in this invention was assembled into a lithium-ion coin cell for electrochemical performance testing. Within a voltage range of 3.0–4.65 V and at 1 C, the first-cycle discharge energy density of this cathode material was greater than 1000 Wh / kg, and the first-cycle discharge energy density at 10 C was greater than 900 Wh / kg. Furthermore, after 50 cycles at 1 C and a voltage range of 2.0–4.8 V, the capacity retention was greater than 90%, fully demonstrating that the triangular bipyramidal vacancy layered oxide prepared in this invention possesses high energy density, high rate performance, and good cycle stability at high voltages. Therefore, the triangular bipyramidal vacancy layered oxide prepared in this invention exhibits high energy density at high voltages. This high energy density directly depends on the reversible lithium / sodium insertion / extraction capability of the cathode material at high voltages. A higher capacity retention at high voltages indicates stronger structural stability of the material under high voltage, enabling the release of more active ions and thus increasing energy density. When the triangular bipyramidal vacancy layered oxide prepared by this invention is used as a positive electrode material, it exhibits good structural reversibility under high voltage and demonstrates excellent energy density, power density and reversible capacity retention in practical applications.

[0037] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0038] Example 1 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a low-temperature solid-state method. + / Na +Ion exchange yielded LiCoO2, a trigonal bipyramidal vacancy layered oxide.

[0039] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.7 CoO2 was prepared by weighing Na2CO3 and CoCO3 separately at a Na / Co molar ratio of 0.7:1.0. The sodium and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were then spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 500℃ for 6 h in air at a heating rate of 5℃ / min, followed by calcination at 850℃ for 12 h. After natural cooling to room temperature, the P2 type sodium-ion battery layered oxide Na was obtained. 0.7 CoO2; S2: Low-temperature solid phase Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na obtained in step S1 was 10:1. 0.7 CoO2 and lithium source Li2CO3 were ball-milled and mixed evenly, then spread evenly in a ceramic boat and placed in a muffle furnace for solid-phase Li2CO3 reaction at a reaction temperature of 150 °C. + / Na + After ion exchange treatment for 20 h, the material was washed and filtered three times with deionized water, and then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ The lithium source LiNO3 and the lithium intercalation intermediate obtained in step S2 were weighed out in a molar ratio of 0.4:1, mixed evenly, and placed in a microwave oven. After microwave heating (output power of 2000 W) for 1 min, the product obtained was trigonal bipyramidal vacancy layered oxide LiCoO2.

[0040] Figure 1 The layered oxide Na for P2 type sodium-ion batteries prepared in Example 1 of this invention 0.7 The XRD pattern of CoO2 shows that all diffraction peaks belong to the P2 type layered structure, with space group [missing information]. P6 3 mmc .

[0041] Figure 2This is a schematic diagram of the triangular bipyramidal vacancy layered oxide obtained in Example 1 of the present invention, wherein (a) is a traditional O3-type lithium cobalt oxide interstitial tetrahedral vacancy (light blue) model, and (b) is the lithium cobalt oxide interstitial tetrahedral vacancy (light blue) and triangular bipyramidal vacancy (yellow) model in the present invention. Figure 3 As shown in the XRD refinement results, all diffraction peaks of the triangular bipyramidal vacancy layered oxide prepared in Example 1 of this invention belong to the space group. P6 3 mc The layered structure of the oxide results in a triangular bipyramidal vacancy structure. Space group P6 3 mc This thermodynamically metastable structure breaks the tight packing of conventional stable structures, opening up wider migration pathways for lithium ions. Compared to the structure in its most thermodynamically stable state, lithium ions can diffuse more freely and rapidly in the metastable structure, thereby improving the battery's charge / discharge rate and rate performance. Simultaneously, metastable structures typically possess more surface defects and grain boundaries, providing abundant active sites. The increased number of active sites facilitates lithium ion adsorption and desorption, as well as electrochemical reactions. During charge and discharge, more active sites can participate in lithium ion storage and release, improving the material's specific capacity and energy density.

[0042] Traditional O3-type lithium cobalt oxide mainly contains tetrahedral vacancies, such as Figure 2 Figure (a) shows a relatively confined spatial structure. The construction of triangular bipyramidal vacancies breaks the original relatively compact vacancy structure, opening up a wider migration path for lithium ions. Larger diffusion channels mean that lithium ions can move more smoothly within the material, reducing the obstacles caused by the limited space and thus accelerating the diffusion rate. Simultaneously, the unique structure of the triangular bipyramidal vacancies alters the atomic arrangement and electron cloud distribution around the lithium ions, creating a diffusion-friendly environment. This structural optimization reduces the energy required for lithium ion diffusion, allowing for migration with lower energy consumption. The lower diffusion barrier helps improve the diffusion efficiency of lithium ions during charging and discharging, enabling the battery to complete the charging and discharging process more quickly. Therefore, the construction of triangular bipyramidal vacancies facilitates lithium ion diffusion.

[0043] Furthermore, these triangular bipyramidal vacancies also help enhance the structural stability of the cathode material. During battery charging and discharging, the repeated insertion and extraction of lithium ions can generate stress on the cathode material's structure, easily leading to deformation or even collapse. The presence of triangular bipyramidal vacancies can buffer and disperse this stress. Their unique geometry and spatial distribution can effectively absorb and release stress, allowing the material to maintain a relatively stable crystal structure even after multiple charge-discharge cycles. This stable structure helps maintain consistent battery performance and extends battery life.

[0044] Therefore, the triangular bipyramidal vacancy structure provides a larger lithium-ion diffusion channel and a lower diffusion barrier, enabling lithium ions to rapidly insert and extract into the cathode material. Consequently, the battery can quickly complete the charge transfer process during high-rate charge and discharge, meeting the demands of high-current charge and discharge and exhibiting excellent rate performance. Simultaneously, the triangular bipyramidal vacancy structure helps optimize the lithium-ion storage and release process, improving lithium-ion utilization. More lithium ions can participate in the electrochemical reaction, thereby increasing the battery's energy storage and release capabilities and improving energy density output. Furthermore, the enhanced structural stability of the triangular bipyramidal vacancy structure reduces structural damage and loss of active materials during charge and discharge, optimizing the lithium-ion diffusion environment and contributing to improved reversible lithium-ion insertion and extraction efficiency. This allows the battery to maintain a high capacity even after multiple cycles, effectively extending battery life and improving overall battery performance.

[0045] Example 2 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a low-temperature solid-state method. + / Na + Ion exchange, this trigonal bipyramidal vacancy layered oxide LiCo 0.99 Al 0.01 O2.

[0046] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.5 Co 0.99 Al 0.01 O2 was used to weigh out NaOH, Co(OH)2, and nano-Al2O3 with a Na / Co / Al molar ratio of 0.5:0.99:0.01. The sodium, cobalt, and aluminum source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 600℃ for 2 h at a heating rate of 8℃ / min in air atmosphere, followed by calcination at 800℃ for 8 h. After natural cooling to room temperature, the P2 type sodium-ion battery layered oxide Na was obtained. 0.5Co 0.99 Al 0.01 O2; S2: Low-temperature solid phase Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₂ obtained in step S1 was 8:1. 0.5 Co 0.99 Al 0.01 O2 and lithium source, lithium source according to n LiNO3 :n LiOH∙H2O A 1:1 LiNO3-LiOH binary eutectic lithium salt system was selected, and after ball milling and uniform mixing, the mixture was spread evenly in a ceramic boat and placed in a muffle furnace for solid-phase Li reaction at a reaction temperature of 260 °C. + / Na + After ion exchange treatment for 1 h, the material was washed and filtered three times with deionized water. The material was then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source LiOH∙H2O and the lithium intercalation intermediate obtained in step S2 were weighed out in a molar ratio of 1:1, mixed thoroughly, and then placed in a microwave oven. After microwave heating (output power of 500 W) for 300 min, the resulting product was the trigonal bipyramidal vacancy layered oxide LiCo. 0.99 Al 0.01 O2.

[0047] Figure 4 The layered oxide Na for P2 type sodium-ion batteries prepared in Example 2 of this invention 0.5 Co 0.99 Al 0.01 The morphology diagram of O2 shows that the intermediate Na in the P2 structure... 0.5 Co 0.99 Al 0.01 O2 particles are mainly in the form of stacked blocks and flakes, with a particle size of about 5 μm.

[0048] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0049] The battery assembly process is as follows: The positive electrode material, acetylene black, and polyvinylidene fluoride (PVDF) binder prepared in this embodiment are weighed according to a mass ratio of 8:1:1, and then mixed with N-methylpyrrolidone (NMP) to form a slurry. The NMP content is 30 times that of PVDF. This slurry is uniformly coated onto aluminum foil and vacuum dried at 80°C for 12 hours. Then, it is cut into circular electrode sheets with a diameter of 12 mm using a mold. A lithium metal sheet is used as the negative electrode, a Celgard 2400 commercial polypropylene membrane is used as the separator, and LP30 is used as the electrolyte. The cells are assembled into CR2032 coin cells in a glove box filled with inert gas. LP30 is 1M LiPF6 (lithium hexafluorophosphate) dissolved in a mixed solvent of ethylene carbonate (EC) and dimethyl carbonate (DMC) (volume ratio of the mixed solvent 1:1).

[0050] Figure 5 The figure shows the first charge-discharge curves of the triangular bipyramidal vacancy layered oxide obtained in Example 2 of this invention at a voltage range of 3.0~4.7 V and a charge-discharge rate of 1C. As can be seen from the figure, the triangular bipyramidal vacancy layered oxide LiCo... 0.99 Al 0.01 The initial charge / discharge capacities of O2 at 1 C and 3.0–4.7 V are 258.4 mAh / g and 246.3 mAh / g, respectively.

[0051] Example 3 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a low-temperature solid-state method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.96 Mn 0.04 O2.

[0052] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.6 Co 0.96 Mn 0.04 O2 was used to weigh CH3COONa and Co(CH3COO)2 at a Na / Co molar ratio of 0.6:0.96:0.04. The sodium and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 450 °C for 4 h at a heating rate of 4 °C / min in air atmosphere, followed by calcination at 820 °C for 6 h. After natural cooling to room temperature, the P2 type sodium-ion battery layered oxide Na was obtained. 0.6 Co 0.96 Mn 0.04 O2; S2: Low-temperature ultrasonic method for Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₂ obtained in step S1 was 5:1. 0.6 Co 0.96 Mn 0.04 O2 and lithium source, lithium source according to n LiCl :n KCl A LiCl-KCl binary eutectic salt system with a ratio of 4.5:5.5 was selected. After being ball-milled and mixed evenly, the mixture was spread evenly in a ceramic boat and placed in a muffle furnace for solid-phase Li reaction at a reaction temperature of 210℃. + / Na + After ion exchange treatment for 8 hours, the material was washed and filtered three times with deionized water, and then dried in an oven at 100 °C for 6 hours to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source LiOH∙H2O and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.4:1, mixed thoroughly, and then placed in an ultrasonic device. After ultrasonication (frequency 150 kHz) for 120 min, the resulting product was trigonal bipyramidal vacancy layered oxide LiCo. 0.96 Mn 0.04 O2.

[0053] Figure 6 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 3 of this invention 0.96 Mn 0.04 The scanning electron microscope image of O2 shows that the layered oxide LiCo... 0.96 Mn 0.04 O2 particles are mainly in the form of flakes and blocks, evenly distributed, with a particle size of about 5 μm.

[0054] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0055] The battery assembly method and testing method are the same as in Example 2.

[0056] Figure 7 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 3 of this invention 0.96 Mn 0.04 The initial charge-discharge curves of O2 at a voltage range of 3.0–4.65 V and a C of 0.5 C are shown in the figure. As can be seen from the figure, this triangular bipyramidal vacancy layered oxide LiCo... 0.96 Mn 0.04The initial charge / discharge capacities of O2 in the voltage range of 3.0-4.65 V and at 0.5 C are 252 mAh / g and 249.6 mAh / g, respectively.

[0057] Example 4 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a low-temperature solid-state method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.5 Mn 0.5 O2.

[0058] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula NaCo 0.5 Mn 0.5 O2 was used to weigh out CH3COONa, Co(CH3COO)2, and Mn(CH3COO)2 with a Na / Co / Mn molar ratio of 1.0:0.5:0.5. The sodium, cobalt, and manganese source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 450℃ for 4 h in air at a heating rate of 4℃ / min, followed by calcination at 820℃ for 6 h. After natural cooling to room temperature, the P2-type sodium-ion battery layered oxide NaCo was obtained. 0.5 Mn 0.5 O2; S2: Low-temperature solid phase Li + / Na + Ion exchange: According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide NaCo obtained in step S1 was 5:1. 0.5 Mn 0.5 O2 and lithium source, lithium source according to n LiCl :n KCl A LiCl-KCl binary eutectic salt system with a ratio of 4.5:5.5 was selected. After being ball-milled and mixed evenly, the mixture was spread evenly in a ceramic boat and placed in a muffle furnace for solid-phase Li reaction at a reaction temperature of 210℃. + / Na + After ion exchange treatment for 8 hours, the material was washed and filtered three times with deionized water. The material was then dried in an oven at 100 ℃ for 6 hours to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+Lithium source LiCH3COO and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.2:1, mixed thoroughly, and then placed in an ultrasonic device. After ultrasonication (frequency 25 kHz) for 300 min, the resulting product was trigonal bipyramidal vacancy layered oxide LiCo. 0.5 Mn 0.5 O2. After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0059] The battery assembly method and testing method are the same as in Example 2.

[0060] Figure 8 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 4 of this invention 0.5 Mn 0.5 The cycling performance of O2 in the voltage range of 2.0~4.8 V and 1 C is shown in the figure. This indicates that the triangular bipyramidal vacancy layered oxide LiCo... 0.5 Mn 0.5 O2 retains 93.3% of its capacity after 50 cycles at 1 C and a voltage range of 2.0–4.8 V.

[0061] Example 5 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a liquid-phase method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.99 Ni 0.01 O2.

[0062] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.7 Co 0.99 Ni 0.01 CoO2 was prepared by weighing Na2C2O4, CoC2O4, and NiO in a Na / Co / Ni molar ratio of 0.7:0.99:0.01. The sodium, nickel, and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed material was then spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 400℃ for 8 h at a heating rate of 6℃ / min in air, followed by calcination at 780℃ for 15 h. After natural cooling to room temperature, a P2-type sodium-ion battery layered oxide Na was obtained. 0.7 Co 0.99 Ni 0.01 CoO2; S2: Liquid phase Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of Na₂O₂ to Na₂O₂, the P₂ type sodium-ion battery layered oxide prepared in step S1, was weighed out respectively. 0.7 Co 0.99 Ni 0.01 CoO2 and lithium source LiBr, according to 1 g Na 0.7 Co 0.99 Ni 0.01 Prepare a LiBr aqueous solution using CoO2 at a ratio corresponding to 5 mL of lithium source solution. Then, use magnetic stirring to add Na... 0.7 Co 0.99 Ni 0.01 CoO2 was uniformly dispersed in the lithium source solution, and the reaction temperature was controlled at 80 °C to carry out liquid-phase Li... + / Na + After ion exchange treatment for 10 h, the material was washed and filtered three times with deionized water, and then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source LiOH∙H2O and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.3:1, mixed thoroughly, and placed in an oven. After heating at 90°C for 300 min, the resulting product was the trigonal bipyramidal vacancy layered oxide LiCo. 0.99 Ni 0.01 O2.

[0063] Figure 9 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 5 of this invention 0.99 Ni 0.01 The EDS spectrum of O2 shows that the trigonal bipyramidal vacancy layered oxide LiCo prepared in this embodiment... 0.99 Ni 0.01 O2 is evenly distributed in the grains.

[0064] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0065] The battery assembly method and testing method are the same as in Example 2.

[0066] Figure 10 The triangular bipyramidal vacancy layered oxide LiCo obtained in Example 5 of this invention 0.99 Ni 0.01 The cycling performance of O2 at a voltage range of 3.0~4.55 V and a temperature of 0.5 C is shown in the figure. The triangular bipyramidal vacancy layered oxide LiCo prepared in this embodiment exhibits [performance characteristics]. 0.99Ni 0.01 The initial discharge capacity of O2 at 0.5 C in the voltage range of 3.0 to 4.55 V is 216.3 mAh / g, and the capacity retention rate is 89.3% after 100 cycles.

[0067] Example 6 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a liquid-phase method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.99 Y 0.01 O2.

[0068] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.67 Co 0.99 Y 0.01 CoO2 was prepared by weighing NaNO3, Y(NO3)3, and Co(NO3)2 in a Na / Co / Y molar ratio of 0.67:0.99:0.01. The sodium, yttrium, and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were then spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 550℃ for 5 h at a heating rate of 3℃ / min in air, followed by calcination at 750℃ for 20 h. After natural cooling to room temperature, a P2-type sodium-ion battery layered oxide Na was obtained. 0.67 Co 0.99 Y 0.01 O2; S2: Liquid phase Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₂ obtained in step S1 was 6:1. 0.67 Co 0.99 Y 0.01 O2 and lithium source LiNO3, according to 1 g Na 0.67 Co 0.99 Y 0.01 Prepare an ethanol solution of LiNO3 using CoO2 at a ratio corresponding to 250 mL of lithium source solution. Then, use magnetic stirring to add Na... 0.67 Co 0.99 Y 0.01 CoO2 was uniformly dispersed in the lithium source solution, and the reaction temperature was controlled at 60℃ to carry out liquid-phase Li + / Na +After ion exchange treatment for 15 h, the material was washed and filtered three times with ethanol, and then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source Li₂CO₃ and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.5:1, mixed thoroughly, and then placed in a microwave oven. After microwave heating (output power of 2000 W) for 100 min, the resulting product was the trigonal bipyramidal vacancy layered oxide LiCo. 0.99 Y 0.01 O2.

[0069] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0070] The battery assembly method and testing method are the same as in Example 2.

[0071] Figure 11 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 6 of this invention 0.99 Y 0.01 The rate performance of O2 in the voltage range of 3.0~4.6 V is shown in the figure. The triangular bipyramidal vacancy layered oxide LiCo prepared in this embodiment exhibits [performance characteristics]. 0.99 Y 0.01 O2 exhibits good rate performance within a voltage range of 3.0 to 4.6V.

[0072] Example 7 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a liquid-phase method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.99 V 0.01 O2.

[0073] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to Na 0.69 Co 0.99 V 0.01O2 was used to weigh out Na2O2, Co3O4, and V2O5 with a Na / Co / V molar ratio of 0.69:0.99:0.01. The sodium, vanadium, and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 600℃ for 1 h in air at a heating rate of 10℃ / min, followed by calcination at 900℃ for 2 h. After natural cooling to room temperature, the P2-type sodium-ion battery layered oxide Na was obtained. 0.69 Co 0.99 V 0.01 CoO2; S2: Liquid phase Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₃ obtained in step S1 was 15:1. 0.69 Co 0.99 V 0.01 CoO2 and lithium source, the lithium source according to n LiCl :n LiF :n LiBr The ratio of 5:1:4 was selected using a ternary eutectic lithium salt system of LiCl-LiF-LiBr, with 1 g Na... 0.69 Co 0.99 V 0.01 Prepare a lithium source aqueous solution using CoO2 at a ratio corresponding to 100 mL of lithium source solution. Then, use magnetic stirring to add Na... 0.69 Co 0.99 V 0.01 CoO2 was uniformly dispersed in the lithium source solution, and the reaction was carried out in liquid phase at a controlled temperature of 260℃. + / Na + After ion exchange treatment for 0.5 h, the material was washed and filtered three times with ethanol, and then dried in an oven at 100 °C for 6 h to obtain a lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source Li₂C₂O₄ and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.3:1, mixed thoroughly, and then placed in a microwave oven. After microwave heating (output power of 1500 W) for 30 min, the resulting product was the trigonal bipyramidal vacancy layered oxide LiCo. 0.99 V 0.01 O2.

[0074] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0075] The battery assembly method and testing method are the same as in Example 2.

[0076] Figure 12 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 7 of this invention 0.99 V 0.01 The energy density variation of O2 in the voltage range of 3.0~4.65 V and 1 C is shown in the figure. The figure also shows the energy density variation of the trigonal bipyramidal vacancy layered oxide LiCo prepared in this embodiment. 0.99 V 0.01 The first-cycle discharge energy density of O2 at 1 C within a voltage range of 3.0–4.65 V is 1026.8 Wh / kg. (cathode) After 50 cycles, the discharge energy density is still 885.6 Wh / kg. (cathode) .

[0077] Example 8 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a liquid-phase method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.7 Mn 0.3 O2.

[0078] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.69 Co 0.7 Mn 0.3 O2 was used to weigh out Na2O2, Co3O4, and Mn3O4 in a molar ratio of Na:Co:Mn = 0.69:0.7:0.3. The sodium, cobalt, and manganese source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 600℃ for 1 h in air at a heating rate of 10℃ / min, followed by calcination at 900℃ for 2 h. After natural cooling to room temperature, the P2-type sodium-ion battery layered oxide Na was obtained. 0.69 Co 0.7 Mn 0.3 O2; S2: Liquid phase Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₃ obtained in step S1 was 12:1. 0.69 Co 0.7 Mn 0.3 O2 and lithium source, lithium source according to nLiCl :n LiF :n LiBr The ratio of 5:1:4 was selected using a ternary eutectic lithium salt system of LiCl-LiF-LiBr, with 1 g Na... 0.69 Co 0.7 Mn 0.3 Prepare a lithium source aqueous solution using O2 at a ratio corresponding to 100 mL of lithium source solution. Then, use magnetic stirring to add Na... 0.69 Co 0.7 Mn 0.3 O2 was uniformly dispersed in the lithium source solution, and the reaction temperature was controlled at 100℃ to carry out liquid-phase Li... + / Na + After ion exchange treatment for 5 h, the material was washed and filtered three times with ethanol, and then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source LiCH3COO and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.5:1, mixed thoroughly, and then placed in a microwave oven. After microwave heating (output power of 1000 W) for 45 min, the resulting product was the trigonal bipyramidal vacancy layered oxide LiCo. 0.7 Mn 0.3 O2.

[0079] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0080] The battery assembly method and testing method are the same as in Example 2.

[0081] Figure 13 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 8 of this invention 0.7 Mn 0.3 The charge-discharge curves of O2 at a voltage range of 2.0~4.8 V and 1 C are shown in the figure. As can be seen from the figure, the triangular bipyramidal vacancy layered oxide LiCo prepared in this embodiment... 0.7 Mn 0.3 The charging specific capacity of O2 at 2.0~4.8 V and 1 C is 197.8 mAh / g, and the discharging specific capacity is 196 mAh / g.

[0082] Example 9 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a solvothermal method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.99 Cu 0.01O2.

[0083] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.55 Co 0.99 Cu 0.01 O2 was used to weigh out NaOH, CoO, and CuO with a Na / Cu / Co molar ratio of 0.55:0.99 / 0.01. The sodium, copper, and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed material was spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 500℃ for 3 h at a heating rate of 2℃ / min in air atmosphere, followed by calcination at 700℃ for 10 h. After natural cooling to room temperature, the P2 type sodium-ion battery layered oxide Na was obtained. 0.55 Co 0.99 Cu 0.01 O2; S2: Solventothermic Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₃ obtained in step S1 was 2:1. 0.55 Co 0.99 Cu 0.01 O2 and lithium source Li2C2O4, according to 1 g Na 0.55 Co 0.99 Cu 0.01 O2 was used to prepare an ethanol solution of lithium source in 100 mL of lithium source solution. Na was then stirred magnetically. 0.55 Co 0.99 Cu 0.01 O2 was uniformly dispersed in the lithium source solution. The mixed solution was poured into a high-pressure reactor and heated to 100°C for 10 h to perform solvothermal Li + / Na + After ion exchange treatment, the reactor was allowed to cool naturally to room temperature. The mixture was then washed and filtered three times with deionized water. Finally, the material was dried in an oven at 100 °C for 6 hours. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source LiOH∙H2O and the lithium intercalation intermediate obtained in step 2 were weighed out at a molar ratio of 0.5:1, mixed thoroughly, and then placed in an oven and heated at 150℃ for 200 min. The resulting product is the trigonal bipyramidal vacancy layered oxide LiCo. 0.99 Cu 0.01 O2.

[0084] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0085] The battery assembly method and testing method are the same as in Example 2.

[0086] Figure 14 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 9 of this invention 0.99 Cu 0.01 The initial charge-discharge curves of O2 at a voltage range of 3.0–4.6 V and a C of 0.5 C are shown in the figure. As can be seen from the figure, the triangular bipyramidal vacancy layered oxide LiCo prepared in this embodiment... 0.99 Cu 0.01 The initial charge / discharge capacities of O2 at 3.0–4.6 V and 0.5 C are 237.4 mAh / g and 234.7 mAh / g, respectively.

[0087] Example 10 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a solvothermal method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.98 Mg 0.02 O2.

[0088] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.6 Co 0.98 Mg 0.02 O2 was used to weigh out Na2CO3, Co3O4, and MgO with a Na / Co / Mg molar ratio of 0.6:0.98:0.02. The sodium, magnesium, and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 550℃ for 2 h in air at a heating rate of 5℃ / min, followed by calcination at 800℃ for 6 h. After natural cooling to room temperature, the P2 type sodium-ion battery layered oxide Na was obtained. 0.6 Co 0.98 Mg 0.02 O2; S2: Solventothermic Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₃ obtained in step S1 was 15:1. 0.6 Co 0.98 Mg0.02 O2 and lithium source LiCH3COO, according to 1 g Na 0.6 Co 0.98 Mg 0.02 Prepare a lithium source aqueous solution using O2 at a ratio corresponding to 30 mL of lithium source solution. Then, use magnetic stirring to add Na... 0.6 Co 0.98 Mg 0.02 O2 was uniformly dispersed in the lithium source solution. The mixed solution was poured into a high-pressure reactor and heated to 220°C for 1 h for solvothermal Li + / Na + After ion exchange treatment, the reaction vessel was naturally cooled to room temperature. The mixture was washed and filtered three times with deionized water. The material was then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source LiCH3COO and the lithium intercalation intermediate obtained in step S2 were weighed at a molar ratio of 0.6:1. After microwave heating (output power of 800 W) for 60 min, the resulting product was the trigonal bipyramidal vacancy layered oxide LiCo. 0.98 Mg 0.02 O2.

[0089] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0090] The battery assembly method and testing method are the same as in Example 2.

[0091] Figure 15 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 10 of this invention 0.98 Mg 0.02 The energy density and operating voltage variation of O2 in the voltage range of 3.0~4.65 V and 10 C are shown in the figure. The triangular bipyramidal vacancy layered oxide LiCo prepared in this embodiment... 0.98 Mg 0.02 The first-cycle discharge energy density of O2 is 946.7 Wh / kg at a voltage range of 3.0–4.65 V and a temperature of 10 C. (cathode) After 20 revolutions, the discharge energy density is 927.8 Wh / kg. (cathode) The operating voltage is always maintained above 3.9 V.

[0092] Example 11 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a solvothermal method. + / Na +Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.98 Mn 0.01 Ru 0.01 O2.

[0093] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.65 Co 0.98 Mn 0.01 Ru 0.01 O2 was used to weigh out NaHCO3, Co2O3, MnO2, and RuO2 in a Na / Co / Mn / Ru molar ratio of 0.65:0.98:0.01:0.01. The sodium, manganese, ruthenium, and cobalt source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 450℃ for 7 h in air at a heating rate of 3℃ / min, followed by calcination at 880℃ for 4 h. After natural cooling to room temperature, the P2-type sodium-ion battery layered oxide Na was obtained. 0.65 Co 0.98 Mn 0.01 Ru 0.01 O2; S2: Solventothermic Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₃ obtained in step S1 was 9:1. 0.65 Co 0.98 Mn 0.01 Ru 0.01 O2 and lithium source LiCl, according to 1 g Na 0.65 Co 0.98 Mn 0.01 Ru 0.01 Prepare a lithium source aqueous solution using O2 at a ratio corresponding to 75 mL of lithium source solution. Then, use magnetic stirring to add Na... 0.65 Co 0.98 Mn 0.01 Ru 0.01 O2 was uniformly dispersed in the lithium source solution. The mixed solution was poured into a high-pressure reactor and heated to 100°C for 20 h to perform solvothermal Li + / Na + After ion exchange treatment, the reaction vessel was allowed to cool naturally to room temperature. The mixture was then washed and filtered three times with deionized water. The material was then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+:n Co3+ Lithium source LiOH∙H2O and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.2:1, mixed thoroughly, and then placed in an ultrasonic device. After ultrasonication (frequency 150 kHz) for 100 min, the resulting product was trigonal bipyramidal vacancy layered oxide LiCo. 0.98 Mn 0.01 Ru 0.01 O2.

[0094] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0095] The battery assembly method and testing method are the same as in Example 2.

[0096] Figure 16 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 11 of this invention 0.98 Mn 0.01 Ru 0.01 The initial charge-discharge curves of O2 at 1 C within a voltage range of 3.0–4.55 V are shown in the figure. As can be seen from the figure, the triangular bipyramidal vacancy layered oxide LiCo prepared in this embodiment... 0.98 Mn 0.01 Ru 0.01 The initial charge / discharge capacities of O2 at 1 C and 3.0–4.55 V are 217.3 mAh / g and 215 mAh / g, respectively.

[0097] Example 12 This embodiment provides a preparation process for a triangular bipyramidal vacancy layered oxide, in which Li is prepared by a solvothermal method. + / Na + Ion exchange, the trigonal bipyramidal vacancy layered oxide is LiCo 0.9 Mn 0.1 O2.

[0098] Its preparation process specifically includes the following steps: S1: High-temperature solid-state calcination According to the chemical formula Na 0.65 Co 0.9 Mn 0.1O2 was used to weigh out NaHCO3, Co2O3, and Mn2O3 in a molar ratio of Na:Co:Mn = 0.65:0.9:0.1. The sodium, cobalt, and manganese source materials were mechanically pulverized and uniformly mixed using ball milling. The pulverized and mixed materials were spread evenly in a ceramic boat and placed in a muffle furnace. The furnace was pre-calcined at 450℃ for 7 h in air at a heating rate of 3℃ / min, followed by calcination at 880℃ for 4 h. After natural cooling to room temperature, the P2 type sodium-ion battery layered oxide Na was obtained. 0.65 Co 0.9 Mn 0.1 O2; S2: Solventothermic Li + / Na + Ion exchange According to n Li+ :n Na+ The molar ratio of P2 type sodium-ion battery layered oxide Na₂O₃ obtained in step S1 was 15:1. 0.65 Co 0.9 Mn 0.1 O2 and lithium source LiCl, according to 1 g Na 0.65 Co 0.9 Mn 0.1 Prepare a lithium source aqueous solution using O2 at a ratio corresponding to 75 mL of lithium source solution. Then, use magnetic stirring to add Na... 0.65 Co 0.9 Mn 0.1 O2 was uniformly dispersed in the lithium source solution. The mixed solution was poured into a high-pressure reactor and heated to 100°C for 20 h to perform solvothermal Li + / Na + After ion exchange treatment, the reaction vessel was allowed to cool naturally to room temperature. The mixture was then washed and filtered three times with deionized water. The material was then dried in an oven at 100 °C for 6 h to obtain the lithium intercalation intermediate. S3: Field-enhanced lithiation According to n Li+ :n Co3+ Lithium source LiCH3COO and the lithium intercalation intermediate obtained in step S2 were weighed out at a molar ratio of 0.3:1, mixed thoroughly, and placed in an oven. After heating at 200℃ for 150 min, the resulting product was the trigonal bipyramidal vacancy layered oxide LiCo. 0.9 Mn 0.1 O2.

[0099] After assembling the triangular bipyramidal vacancy layered oxide prepared in this embodiment, its charge-discharge performance was tested.

[0100] The battery assembly method and testing method are the same as in Example 2.

[0101] Figure 17The triangular bipyramidal vacancy layered oxide LiCo prepared in Example 12 of this invention has triangular bipyramidal vacancy sites. 0.9 Mn 0.1 The charge-discharge curves of O2 at a voltage range of 2.0~4.8 V and 1 C are shown in the figure. As can be seen from the figure, the triangular bipyramidal vacancy layered oxide LiCo prepared in this embodiment... 0.9 Mn 0.1 The initial charge / discharge capacities of O2 at 1 C and within a voltage range of 2.0–4.8 V are 226.9 mAh / g and 224.4 mAh / g, respectively. at the same time, Figure 18 The trigonal bipyramidal vacancy layered oxide LiCo obtained in Example 12 of this invention 0.9 Mn 0.1 The cycling performance of O2 in the voltage range of 3.0~4.65 V and 1 C is shown in the figure. It can be seen that the triangular bipyramidal vacancy layered oxide prepared in this embodiment has a capacity retention of 87% after 100 cycles in the voltage range of 3.0~4.65 V and 1 C.

[0102] In summary, this invention discloses a triangular bipyramid vacancy layered oxide and its preparation method. This layered oxide possesses a triangular bipyramid vacancy (TBV) structure. The preparation method first synthesizes a sodium-containing layered oxide intermediate through high-temperature solid-state calcination, which is beneficial for improving the tap density of the material. The process is simple, mature, and offers high equipment compatibility and scalability. Secondly, multiple pathways, including solid-phase, liquid-phase, and solvothermal methods, can be used for low-temperature ion exchange treatment. The low-temperature solid-phase ion exchange pathway produces layered oxides with high crystallinity, high tap density, and no liquid-phase residue contamination, making it suitable for large-scale production. The liquid-phase ion exchange pathway offers mild reaction conditions, good uniformity, wide applicability, and effectively maintains the intermediate morphology. The solvothermal ion exchange pathway utilizes the high diffusivity of the solvent under high temperature and high pressure conditions to achieve the dual advantages of solid-phase crystallinity and liquid-phase reactivity. All three pathways can achieve controllable ion exchange at relatively low temperatures, and the triangular bipyramidal vacancy layered oxides prepared by external field-enhanced lithiation reactions are all thermodynamically metastable layered structures of pure phase, possessing unique interstitial triangular bipyramidal vacancies, which can provide larger lithium-ion diffusion channels, lower lithium-ion diffusion barriers, and stronger structural stability. The triangular bipyramidal vacancy layered oxides prepared by this invention have high purity, uniform particle distribution, controllable particle size, and good batch uniformity. Furthermore, this invention also discloses the application of this triangular bipyramidal vacancy layered oxide in lithium-ion batteries. During electrochemical performance testing in lithium-ion coin cells, within a voltage range of 3.0–4.65 V, the 1C first-cycle discharge energy density reached 1027 Wh / kg. (cathode) The energy density of the first 10C discharge reached 947Wh / kg.(cathode) In practical applications, it exhibits excellent energy density, power density, and reversible capacity retention.

[0103] This invention discloses a method for preparing triangular bipyramidal vacancy layered oxides, providing three low-temperature controllable ion exchange pathways: solid-phase, liquid-phase, and solvothermal. The low-temperature solid-phase ion exchange pathway yields layered oxides with high crystallinity, high tap density, and no liquid-phase residue contamination, suitable for large-scale production. The liquid-phase ion exchange pathway offers mild reaction conditions, good uniformity, wide applicability, and effectively maintains the intermediate morphology. The solvothermal ion exchange pathway utilizes the high diffusivity of the solvent under high temperature and high pressure conditions to achieve the dual advantages of solid-phase crystallinity and liquid-phase reactivity. Based on this, the triangular bipyramidal vacancy layered oxides for lithium-ion batteries prepared using an external field-enhanced lithiation strategy are all pure-phase thermodynamically metastable layered structures with unique interstitial triangular bipyramidal vacancies, providing larger lithium-ion diffusion channels, lower lithium-ion diffusion barriers, and stronger structural stability. The obtained triangular bipyramidal vacancy layered oxide particles are uniformly distributed, with controllable particle size and good batch uniformity. In practical applications, they exhibit excellent energy density, power density, and reversible capacity retention, providing a new approach for the development of lithium-ion batteries with both high energy density and high power density.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a trigonal bipyramidal vacancy layered oxide, characterized in that, Includes the following steps: S1: After uniformly mixing sodium source, cobalt source and / or raw materials containing element M, calcination is performed to obtain the layered oxide Na for P2 type sodium-ion batteries. x Co y M 1-y O2, where 0.50≤x≤1.00, 0.50≤y≤1.00; S2: The P2 type sodium-ion battery layered oxide Na x Co y M 1-y O2 is mixed with the first lithium source and reacted at 60~260℃ to obtain a lithium intercalation intermediate; S3: The lithium intercalation intermediate is mixed uniformly with a second lithium source, and the resulting mixture is subjected to external field treatment, including electromagnetic field treatment, thermal field treatment, or ultrasonic treatment, to obtain a triangular bipyramidal vacancy layered oxide LiCo. y M 1- y O2, where 0.50≤y≤1.

00.

2. The method for preparing a trigonal bipyramidal vacancy layered oxide according to claim 1, characterized in that, In step S1, the calcination process is as follows: the temperature is raised to 400-600℃ at a heating rate of 2-10℃ / min, pre-calcined for 1-8 h, and then calcined at 700-900℃ for 2-20 h to complete the calcination process.

3. The method for preparing a trigonal bipyramidal vacancy layered oxide according to claim 1, characterized in that, In step S1, element M is at least one of potassium, aluminum, beryllium, boron, fluorine, magnesium, calcium, strontium, scandium, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, tantalum, tungsten, rhenium, osmium, iridium, and platinum.

4. The method for preparing a trigonal bipyramidal vacancy layered oxide according to claim 1, characterized in that, In step S2, lithium ions in the first lithium source react with the layered oxide Na of the P2 type sodium ion battery. x Co y M 1-y The molar ratio of sodium ions in O2 is (1.0~15):

1.

5. The method for preparing a trigonal bipyramidal vacancy layered oxide according to claim 1, characterized in that, In step S2, the layered oxide Na of the P2 type sodium-ion battery is processed using solid-phase method, liquid-phase method, and hydrothermal method. x Co y M 1-y O2 reacts with the first lithium source to prepare a lithium intercalation intermediate.

6. The method for preparing a trigonal bipyramidal vacancy layered oxide according to claim 1, characterized in that, In step S3, when the external field treatment is electromagnetic field treatment, the output power of the electromagnetic field is 500~2000 W; when the external field treatment is thermal field treatment, the temperature of the thermal field is 90~200 ℃; when the external field treatment is ultrasonic field treatment, the ultrasonic frequency is 25~150 kHz.

7. The method for preparing a trigonal bipyramidal vacancy layered oxide according to claim 1, characterized in that, In step S3, the time for the field treatment is 1 to 300 minutes.

8. The method for preparing a trigonal bipyramidal vacancy layered oxide according to claim 1, characterized in that, In step S3, the molar ratio of lithium ions in the second lithium source to cobalt ions in the lithium intercalation intermediate is (0.2~1):

1.

9. A trigonal bipyramidal vacancy layered oxide, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. The application of the triangular bipyramidal vacancy layered oxide as described in claim 9 in a lithium-ion battery.

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