Preparation method of lithium oxide as well as product and application of lithium oxide

Abstract

The invention discloses a preparation method of lithium oxide and a product and application thereof, and the method comprises the following steps: mixing a lithium-containing raw material with a rare earth oxide to form a pretreated material; the rare earth oxide is at least one of La2O3 and CeO2, and the addition amount of the rare earth oxide is 1-10 wt% of the total mass of the lithium-containing raw material; the pretreated material is subjected to gradient pyrolysis, and the gradient pyrolysis comprises the steps that under the inert atmosphere of 200-300 DEG C, the pretreated material is subjected to dehydration treatment for 1-2 hours, crystal water and light metal impurities are removed, and a dehydrated material is obtained; raising the reaction temperature of the dehydrated material to 400 + / -5 DEG C, and keeping the reaction temperature for 1-3 hours at the constant temperature, so that rare earth ions in the rare earth oxide are embedded into crystal lattices of the dehydrated material to form a doped intermediate; enabling the doped intermediate to react for 1.5-2 hours in an oxidizing atmosphere at 600 + / -10 DEG C so as to finish a final pyrolytic reaction and generate lithium oxide; oxygen vacancies can be repaired, the crystal structure is stabilized, and impurity adsorption is reduced.

Description

Technical Field

[0001] This invention relates to the field of inorganic compound synthesis technology, and in particular to a method for preparing lithium oxide, its products, and applications. Background Technology

[0002] Lithium oxide (Li₂O) is a core precursor for high-energy-density solid-state batteries, and the quality of its synthesis process directly determines the battery's energy density and cycle life. Currently, industrial production of lithium oxide mainly relies on two technical routes: high-temperature solid-state method and solution method.

[0003] While the high-temperature solid-state method is simple, it suffers from significant drawbacks, including high reaction temperatures (typically ≥800℃), enormous energy consumption, easy residue of alkali metal impurities, and numerous crystal defects in the product. Solution methods can improve purity to some extent, but face challenges such as complex processes, high costs, and difficulties in scaling up production. Although some improved processes have emerged in recent years, systemic deficiencies remain in thermal management, purity enhancement, and defect suppression: for example, reliance on multi-stage filtration for impurity removal fails to effectively repair lattice defects, and it exhibits poor adaptability to low-grade raw materials.

[0004] Overall, existing lithium oxide synthesis technologies are deeply mired in the "three highs dilemma": 1. High energy consumption: Due to thermodynamic limitations, the reaction temperature is high, and energy consumption costs account for more than 40% of the total cost; 2. High impurities: Severe residues of alkali metals (such as sodium and potassium) lead to rapid degradation of battery electrochemical performance; for example, the capacity retention rate is often less than 80% after 100 cycles. 3. High defect rate: The products exhibit high lattice disorder, with ionic conductivity generally below 10. -5 S / cm, which is insufficient to meet the requirements of solid-state batteries for electrolyte materials with ionic conductivity (>10). -4 The basic requirements for S / cm.

[0005] Therefore, the industry urgently needs to develop an industrial preparation technology that can be carried out under low-temperature and energy-saving conditions, can produce high-purity lithium oxide with a stable crystal structure, and can be adapted to low-grade lithium resources such as industrial-grade raw materials and even waste lithium battery fluid. Summary of the Invention

[0006] One object of the present invention is to provide a method for preparing lithium oxide, as well as its products and applications, to solve the technical problems in the background art mentioned above.

[0007] A method for preparing lithium oxide includes the following steps: Lithium-containing raw materials are mixed with dopants to obtain a mixture. The mixture is subjected to heat treatment, which includes at least structural stabilization treatment in a first temperature range and high-temperature pyrolysis in a second temperature range. During the high-temperature pyrolysis stage, intermittent negative pressure is applied to remove volatile impurities from the lithium-containing raw material.

[0008] Compared to existing technologies, the beneficial effects of this invention are as follows: by decoupling the traditional single high-temperature reaction (≥800℃) into multiple steps carried out in the medium and low temperature range (e.g., 350-750℃) through multi-stage heat treatment, the thermodynamic path of the reaction is reconstructed, significantly reducing the reaction activation energy and the total energy consumption of the process. Compared to existing technologies, the peak reaction temperature is reduced by more than 150℃, and the energy consumption per unit product can be reduced by about 60%, fundamentally overcoming the "high energy consumption" dilemma.

[0009] Applying intermittent negative pressure during the high-temperature pyrolysis stage creates a physical driving force for impurity removal, enabling efficient and targeted removal of gaseous alkali metal impurities such as sodium and potassium from the reaction system. This method avoids the re-residue of impurities during lattice cooling, allowing the total amount of sodium and potassium impurities in the final lithium oxide product to be controlled below 100 ppm, thus solving the battery performance degradation problem caused by "high impurities".

[0010] In the structural stabilization stage, pre-embedded dopants act as atomic-level templates and pinning points, effectively guiding the orderly growth of the lithium oxide lattice and repairing defects such as vacancies and dislocations. The resulting lithium oxide crystal structure is complete with low dislocation density, and its ionic conductivity is expected to be improved by an order of magnitude, meeting the requirements of solid-state battery electrolytes (>10). -4 By meeting the requirements of S / cm, the technical bottleneck of "high defects" was overcome.

[0011] Furthermore, the dopant is selected from at least one of La2O3, CeO2, Y2O3, and Gd2O3.

[0012] Furthermore, the dopant is a mixture of La2O3 and CeO2, and the mass ratio of La2O3 to CeO2 is (1:1) to (3:1).

[0013] Furthermore, the amount of the lattice stabilizer added is 0.5%-15% of the total mass of the lithium-containing raw material.

[0014] Furthermore, the lithium-containing raw material includes at least one of lithium hydroxide, lithium carbonate, lithium nitrate, and recycled waste lithium battery materials.

[0015] Furthermore, the heat treatment also includes dehydration pretreatment of the mixture in a third temperature range; The temperature in the third temperature range is 150°C to 350°C; The first temperature range is 350°C to 500°C; The second temperature range is 550°C to 750°C.

[0016] Furthermore, the intermittent negative pressure is applied in the form of periodic vacuum pulses, the period of which is 3-15 minutes and the duration of each pulse is 20 to 90 seconds.

[0017] Furthermore, the oxidative pyrolysis is carried out in an oxygen-containing atmosphere, which includes air, oxygen, and a mixture of inert gases.

[0018] In addition, the present invention also provides lithium oxide prepared by the above method, wherein the lithium oxide has a purity ≥99.8%, sodium residue ≤50ppm, potassium residue ≤20ppm, and specific surface area ≥15m² / g.

[0019] Furthermore, the present invention also provides the application of the aforementioned lithium oxide in the preparation of solid-state battery electrolytes or as an electrode pre-lithiation additive.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of a method for preparing lithium oxide according to the first embodiment of the present invention.

[0023] Figure 2 The flowchart of the gradient pyrolysis-rare earth doping-vacuum pulse synergistic process provided in the first embodiment of the present invention is shown. Detailed Implementation

[0024] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below with reference to examples. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be more thorough and complete.

[0025] The present invention provides a method for preparing lithium oxide, comprising the following steps: Lithium-containing raw materials are mixed with rare earth oxides to form a pretreated material; the rare earth oxides are at least one of La2O3 and CeO2, and their addition amount is 1-10 wt% of the total mass of the lithium-containing raw materials. The pretreated material is subjected to gradient pyrolysis, the gradient pyrolysis comprising: The pretreated material is dehydrated for 1-2 hours under an inert atmosphere at 200-300℃ to remove crystal water and light metal impurities, thereby obtaining dehydrated material. The reaction temperature of the dehydrated material is raised to 400±5℃ and kept at this temperature for 1-3 hours, so that the rare earth ions in the rare earth oxide are embedded in the crystal lattice of the dehydrated material to form a doped intermediate. The doped intermediate is reacted in an oxidizing atmosphere at 600±10℃ for 1.5-2 hours to complete the final pyrolysis reaction and generate lithium oxide. At the end of the lithium oxide generation stage, periodic vacuum pulses are applied with a pressure ≤10Pa to remove volatile sodium and potassium impurities from the interior, ultimately obtaining a high-purity lithium oxide product.

[0026] The lithium-containing raw material is industrial-grade lithium hydroxide monohydrate or acid leaching solution from waste lithium batteries.

[0027] The oxidizing atmosphere is dry air with an oxygen volume fraction of 18-21%.

[0028] The rare earth oxide is a mixture of La2O3 and CeO2, and the mass ratio of La2O3 to CeO2 is (1:1) to (3:1).

[0029] The heating rate for raising the reaction temperature to 400±5℃ is 5-10℃ / min.

[0030] The periodic vacuum pulse is applied once every 5-10 minutes, and each pulse lasts for 30-60 seconds.

[0031] The method further includes, after the step of generating the lithium oxide, the following steps: The lithium oxide product was cooled to room temperature under inert gas protection.

[0032] The lithium oxide has a purity of ≥99.8%, a sodium residue of ≤50ppm, a potassium residue of ≤20ppm, and a specific surface area of ​​≥15m² / g.

[0033] The lithium oxide is used in the preparation of solid-state battery electrolytes or as an electrode pre-lithiation additive.

[0034] It is worth noting that this invention aims to provide a lithium oxide preparation method based on the synergistic effect of gradient pyrolysis, rare earth doping, and pulsed vacuum. This method aims to solve the problems of high energy consumption, high impurity content, and numerous crystal defects in existing technologies through process innovation, achieving low-temperature, energy-saving, and efficient synthesis of high-purity lithium oxide, and expanding its compatibility with low-grade raw materials. This provides a low-cost, high-performance key material for applications such as solid-state batteries. Through the synergistic effect of gradient pyrolysis, rare earth doping, and pulsed vacuum, the reaction thermodynamic path is reconstructed, enabling conversion at lower temperatures while simultaneously achieving lattice stabilization and targeted impurity removal.

[0035] The further improvements and advantages of the present invention are as follows: Raw material adaptability: The lithium-containing raw material can be industrial-grade lithium hydroxide monohydrate (Na≤1200ppm) or waste lithium battery acid leaching solution, which significantly reduces the cost of raw materials and realizes resource recycling.

[0036] Rare earth synergy: Preferably, the mass ratio of La2O3 to CeO2 in the rare earth oxide is (1:1) to (3:1), utilizing La³⁺ + The lattice expansion effect compensates for sintering stress, Ce 4+ The filling effect repairs oxygen vacancies and jointly optimizes ion migration channels.

[0037] Process optimization: The oxidizing atmosphere is preferably dry air with an oxygen volume fraction of 18-21%, which can both consume by-product hydrogen to prevent a reducing environment and ensure that impurities are effectively removed in the form of oxides. The heating rate in the second stage is controlled at 5-10℃ / min to ensure uniform diffusion of rare earth ions. Vacuum pulses are preferably applied every 5-10 minutes, with each pulse lasting 30-60 seconds, to achieve efficient and energy-saving impurity removal.

[0038] Product performance: The final lithium oxide product has a purity of ≥99.8%, sodium residue ≤50ppm, potassium residue ≤20ppm, specific surface area ≥15 m² / g, and dislocation density ≤10. 6 / cm². The energy consumption per unit product in the entire preparation process is ≤1.8 kWh / kg, and the total reaction time is ≤7 hours.

[0039] This invention proposes three key breakthrough directions: (1) Rare earth doping stabilizes the crystal lattice: Lanthanide rare earth oxides are introduced to embed into the precursor lattice during pyrolysis, thereby pre-constructing a stable structure and fundamentally suppressing lattice distortion and defect generation. (2) Gradient pyrolysis synergistic energy saving: adopt a segmented temperature control strategy (200℃→400℃→600℃) to complete the dehydration, doping and conversion reactions step by step, reconstruct the thermodynamic path, and reduce the peak reaction temperature by more than 200℃ compared with the traditional process; (3) Pulsed vacuum directional impurity removal: Periodic high vacuum pulses are applied at the end of the reaction to target and remove volatile sodium and potassium impurities, thereby achieving deep purification.

[0040] The embodiments of the present invention will be further described below with reference to several examples. The embodiments of the present invention are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of unchanged main claims.

[0041] Example 1 In the first embodiment of the invention, as Figure 1 and Figure 2 As shown, a method for preparing lithium oxide includes the following steps S01-S03: S01, Lithium-containing raw materials are mixed with dopants to obtain a mixture; Specifically, the dopant is a rare earth oxide, selected from at least one of La2O3, CeO2, Y2O3, and Gd2O3, and its addition amount is 1-10 wt% of the total mass of the lithium-containing raw material. In this embodiment, industrial-grade lithium hydroxide monohydrate (LiOH·H2O, sodium impurity content of 1200 ppm) was weighed as the lithium-containing raw material. High-purity (≥99.9%) lanthanum oxide (La2O3) and cerium oxide (CeO2) were weighed and mixed at a mass ratio of 1:1. The total amount of mixed rare earth oxides added was 5 wt% of the mass of lithium hydroxide monohydrate.

[0042] The above raw materials were placed in a ball mill jar, and anhydrous ethanol was used as the wet ball milling medium, with the ball-to-material mass ratio controlled at 10:1. The mixture was ball-milled for 4 hours under an inert atmosphere protected by argon to obtain a uniform pretreated material with a particle size D50 ≤ 5 μm.

[0043] S02, heat treatment is performed on the mixture, the heat treatment including at least structural stabilization treatment in a first temperature range and high-temperature pyrolysis in a second temperature range; In this embodiment, the pretreated material is transferred to a temperature-controlled thermal coupling reaction chamber and subjected to gradient pyrolysis according to a set program: Dehydration stage: High-purity nitrogen gas (flow rate of 100 mL / min) is introduced into the reaction chamber, and the temperature of the reaction system is raised to 200℃ at a heating rate of 5℃ / min. The temperature is then kept constant at 200℃ for 1 hour to remove crystal water and light metal impurities, thereby obtaining dehydrated material.

[0044] Doping stage: Maintaining a nitrogen atmosphere, the reaction system temperature was raised to 400℃ at a heating rate of 8℃ / min and held at that temperature for 2 hours, allowing La³⁺ to react. + and Ce 4+ Ions are embedded in the material lattice to form stable doped intermediates.

[0045] Conversion and purification stage: The atmosphere was switched to dry air (oxygen volume fraction approximately 21%), and the reaction system temperature was raised to 600℃ at a heating rate of 5℃ / min for oxidation. The reaction was held at this temperature for 1.5 hours. 0.5 hours after the start of the isothermal period, a vacuum pulse program was initiated: a vacuum pulse with a pressure ≤10 Pa was applied every 10 minutes, lasting 30 seconds each time, for a total of 6 cycles, to target and remove volatile sodium and potassium impurities. Through online monitoring, when the Li₂O formation rate was ≥99.5%, the system automatically adjusted the temperature control accuracy to within ±5℃ to ensure complete reaction.

[0046] In this embodiment, after the reaction is completed, heating is stopped, and the product is allowed to cool naturally to room temperature under the protection of continuous high-purity argon gas, resulting in a white powdered lithium oxide product.

[0047] It is worth noting that the product performance was characterized as follows: The obtained product was tested, and the results showed that the lithium oxide (Li₂O) purity reached 99.82%, the sodium residue was 45 ppm, the potassium residue was 15 ppm, and the specific surface area was 16.3 m² / g. The calculated energy consumption per unit product for this process was 1.7 kWh / kg.

[0048] Example 2 The difference between this embodiment and Embodiment 1 is that the rare earth oxide is only La2O3, and the amount added is still 5wt%. The remaining steps and parameters are exactly the same as in Embodiment 1.

[0049] Example 3 The difference between this embodiment and Embodiment 1 is that the rare earth oxide is only CeO2, and the amount added is still 5 wt%. The remaining steps and parameters are exactly the same as in Embodiment 1.

[0050] Example 4 The difference between this embodiment and Example 1 is that the total amount of mixed rare earth oxides (La2O3:CeO2 mass ratio 1:1) added is 3wt%. The remaining steps and parameters are exactly the same as in Example 1.

[0051] Example 5 The difference between this embodiment and Example 1 is that the total amount of mixed rare earth oxides (La2O3:CeO2 mass ratio 1:1) added is 7wt%. The remaining steps and parameters are exactly the same as in Example 1.

[0052] Example 6 The difference between this embodiment and Embodiment 1 is that the temperature during the dehydration stage is 250°C. The remaining steps and parameters are exactly the same as in Embodiment 1.

[0053] Example 7 The difference between this embodiment and Example 1 is that the reaction temperature during the transformation and purification stage is 550°C. The remaining steps and parameters are exactly the same as in Example 1.

[0054] Example 8 The difference between this embodiment and Embodiment 1 is that the vacuum pulse application cycle is changed to once every 5 minutes. The remaining steps and parameters are exactly the same as in Embodiment 1.

[0055] Example 9 The difference between this embodiment and Embodiment 1 is that the lithium-containing raw material is replaced with an acid leaching solution recovered from spent lithium iron phosphate batteries (after concentration and purification, the lithium ion concentration is approximately 2 mol / L). The acid leaching solution is mixed with a rare earth oxide slurry and then spray-dried at 120°C to obtain precursor powder, which is then subjected to subsequent gradient pyrolysis steps. All other pyrolysis parameters are identical to those in Embodiment 1.

[0056] Comparative Example 1 (Traditional High-Temperature Solid-State Method) The same batch of industrial-grade lithium hydroxide monohydrate (LiOH·H2O, sodium impurity content of about 1200 ppm) was placed directly in a muffle furnace and calcined at 800°C for 4 hours in air atmosphere. After cooling, lithium oxide product was obtained.

[0057] Comparative Example 2 (without rare earth doping) The same steps as in Example 1 were used, but without adding any rare earth oxides.

[0058] Comparative Example 3 (No Vacuum Pulse) The same steps as in Example 1 were used, but vacuum pulses were not applied during the conversion and purification stages.

[0059] To better illustrate the present invention, the test results of the key performance indicators of the products obtained in Examples 1-9 and Comparative Examples 1-3 are listed in Table 1 below.

[0060]

[0061] Table 1 In summary, the comparison of experimental data from Examples 1-9 and Comparative Examples 1-3 fully verifies the significant advantages of the lithium oxide preparation method based on gradient pyrolysis, rare earth doping, and vacuum pulse synergy provided by this invention.

[0062] The method of this invention demonstrates superior performance in terms of product purity and energy consumption control. The lithium oxide products prepared in Examples 1-9 all have a purity ≥99.8%, sodium residue ≤65 ppm (preferred examples may have ≤50 ppm), and energy consumption per unit product ≤2.0 kWh / kg. Compared with the traditional high-temperature solid-state method (Comparative Example 1, energy consumption 4.5 kWh / kg, sodium impurities 300 ppm), energy consumption is reduced by more than 55%, and purity is significantly improved, successfully overcoming the "high energy consumption, high impurities" dilemma of existing technologies.

[0063] Data analysis reveals the indispensable synergistic effect among the various technical features of this invention: The directional impurity removal effect of pulsed vacuum: Periodic vacuum pulses can effectively physically remove volatile sodium and potassium impurities. As shown in Example 8, shortening the vacuum pulse cycle to 5 minutes can further reduce the sodium impurity content to 35 ppm, demonstrating the key role of this step in achieving ultra-high purity.

[0064] Lattice stabilization effect of rare earth doping: rare earth ions (La³⁺) + Ce 4+ The embedding of rare earth oxides can chemically repair lattice defects, form a stable framework, and reduce impurity adsorption sites. As shown in Example 5, appropriately increasing the amount of rare earth oxides added (7wt%) helps to further reduce the impurity content. The impurity content of Comparative Example 2 (without rare earth doping) (150 ppm) is much higher than that of the examples, proving that the absence of the doping step leads to unstable crystal structure and easy retention of impurities.

[0065] Energy saving and process optimization effects of gradient pyrolysis: The staged temperature-controlled gradient pyrolysis strategy avoids energy consumption peaks and side reactions caused by materials being subjected to high temperatures instantaneously. As shown in Example 7, the conversion is completed at a relatively low temperature of 550℃, with energy consumption as low as 1.6 kWh / kg. The high energy consumption of Comparative Example 1 highlights the core value of gradient pyrolysis in reconstructing thermodynamic pathways and achieving energy saving and consumption reduction.

[0066] This invention is not a simple superposition of technical features, but rather a highly efficient "process-material" energy-saving closed loop formed through the triple synergy of gradient pyrolysis (process), rare earth doping (material), and pulsed vacuum (process): gradient pyrolysis provides the conditions for low-temperature reaction, rare earth doping improves the intrinsic reaction efficiency and structural stability of the material, and pulsed vacuum ensures the extremely high purity of the final product. Comparative Example 3 (without vacuum pulse) had excessive impurity content (100 ppm), proving that even with the first two steps, the lack of a vacuum pulse still cannot achieve optimal results, highlighting the necessity of the synergy of the three.

[0067] In summary, this invention successfully provides an industrial-scale lithium oxide preparation method that combines low-temperature energy saving, high purity, and broad raw material adaptability through a triple synergistic technology of gradient pyrolysis reconstructing the reaction path, rare-earth doping stabilizing the crystal structure, and pulsed vacuum targeted impurity removal. This method can directly process industrial-grade raw materials and even recycled battery solutions, significantly reducing production costs. Furthermore, the resulting lithium oxide product exhibits excellent key performance indicators, providing a reliable material foundation for high-performance solid-state batteries and possessing significant industrial application value.

[0068] In summary, this application has the following beneficial effects: By combining "pulsed vacuum directional impurity removal" with "rare earth lattice locking," the problems of residual alkali metal impurities and lattice defects are effectively solved. Pulsed vacuum can target and remove volatile sodium and potassium impurities; rare earth ions (La³⁺) can also be removed. + Ce 4+ The insertion of these elements can repair oxygen vacancies, stabilize the crystal structure, and reduce impurity adsorption. Examples show that the resulting lithium oxide has a purity ≥99.8%, with sodium and potassium residues ≤50ppm and ≤20ppm respectively, exhibiting a low dislocation density far superior to traditional high-temperature processes (sodium impurities ≥300ppm), thus meeting the stringent requirements of solid-state batteries for the electrochemical stability of materials.

[0069] By reconstructing the thermodynamic path through "gradient pyrolysis," the reaction is decomposed into three optimized stages: dehydration, doping, and conversion, avoiding energy waste caused by instantaneous high temperatures in materials. This process reduces the peak reaction temperature from ≥800℃ to around 600℃. Combined with the effective utilization of waste heat in the system, the energy consumption per unit product is ≤1.8 kWh / kg, which is more than 60% lower than that of traditional methods (energy consumption of approximately 4.5 kWh / kg), significantly reducing production costs.

[0070] Leveraging the mechanisms of "segmented impurity removal" and "lattice defect repair," this method has low requirements for raw material purity and is compatible with high-impurity raw materials such as industrial-grade lithium hydroxide monohydrate (Na≤1200ppm) and even waste lithium battery acid leaching solutions. This significantly broadens the sources of lithium, reduces dependence on high-purity lithium salts, and provides a reliable path for the economic utilization of waste batteries and low-grade lithium ores (such as lepidolite), aligning with the resource recycling strategy.

[0071] This invention is not a simple superposition of process units, but rather achieves deep synergy between "gradient pyrolysis (process) - rare earth doping (material) - vacuum pulse (process)" to form an energy-saving closed loop. This synergistic effect results in products with not only high purity but also a large specific surface area (≥15m² / g) and good sphericity (≥95%), which is beneficial for improving their ionic conductivity and interfacial compatibility in solid-state battery electrolytes or pre-lithiation additives.

[0072] The gradient heating mode avoids the risk of toxic gases being generated by the instantaneous decomposition of organic matter. The entire process is carried out in a closed system, and waste gas and impurities can be treated in a controlled manner, making it environmentally friendly and significantly improving operational safety.

[0073] The present invention also provides lithium oxide products prepared by the method described above.

[0074] The present invention also provides the application of the above-described lithium oxide product, lithium oxide, in the preparation of solid-state battery electrolytes or as an electrode pre-lithiation additive.

[0075] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0076] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing lithium oxide, characterized in that, Includes the following steps: Lithium-containing raw materials are mixed with dopants to obtain a mixture. The mixture is subjected to heat treatment, which includes at least structural stabilization treatment in a first temperature range and high-temperature pyrolysis in a second temperature range. During the high-temperature pyrolysis stage, intermittent negative pressure is applied to remove volatile impurities from the lithium-containing raw material.

2. The method for preparing lithium oxide according to claim 1, characterized in that, The dopant is selected from at least one of La2O3, CeO2, Y2O3, and Gd2O3.

3. The method for preparing lithium oxide according to claim 2, characterized in that, The dopant is a mixture of La2O3 and CeO2, and the mass ratio of La2O3 to CeO2 is (1:1) to (3:1).

4. The method for preparing lithium oxide according to claim 2, characterized in that, The amount of the lattice stabilizer added is 0.5%-15% of the total mass of the lithium-containing raw material.

5. The method for preparing lithium oxide according to claim 1, characterized in that, The lithium-containing raw materials include at least one of lithium hydroxide, lithium carbonate, lithium nitrate, and recycled waste lithium batteries.

6. The method for preparing lithium oxide according to claim 1, characterized in that, The heat treatment also includes dehydration pretreatment of the mixture in a third temperature range; The temperature in the third temperature range is 150°C to 350°C; The first temperature range is 350°C to 500°C; The second temperature range is 550°C to 750°C.

7. The method for preparing lithium oxide according to claim 1, characterized in that, The intermittent negative pressure is applied in the form of periodic vacuum pulses, the period of which is 3-15 minutes and the duration of each pulse is 20 to 90 seconds.

8. The method for preparing lithium oxide according to claim 1, characterized in that, The oxidative pyrolysis is carried out in an oxygen-containing atmosphere, which includes air, oxygen, and a mixture of inert gases.

9. A lithium oxide prepared by the method according to any one of claims 1-8, characterized in that: The lithium oxide has a purity of ≥99.8%, a sodium residue of ≤50ppm, a potassium residue of ≤20ppm, and a specific surface area of ​​≥15m² / g.

10. The use of lithium oxide according to claim 9 in the preparation of solid-state battery electrolytes or as an electrode pre-lithiation additive.

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