Method for preparing submicron LALZO solid electrolyte powder material with assistance of laser heating

Abstract

The invention provides a method for preparing a submicron LALZO solid electrolyte powder material assisted by laser heating. The method comprises the following steps: preparing aluminum-doped lithium lanthanum zirconium oxide (LALZO) precursor powder through a sol-gel method; and placing the LALZO precursor powder on a high thermal conductivity substrate, and carrying out rapid calcination treatment on the LALZO precursor powder by using a flat-top laser to obtain the submicron LALZO solid electrolyte powder material. According to the invention, the crystallization process is shortened to a minute level by using laser energy, so that the production efficiency is greatly improved, and the energy consumption is reduced; grain growth and lithium volatilization can be effectively inhibited, and the submicron powder with the average particle size of 500-1000 nm, uniform distribution and a cubic phase structure is obtained.

Description

Technical Field

[0001] This disclosure relates to the field of all-solid-state battery electrolyte material preparation technology, and in particular to a method for rapidly heating and preparing garnet-type lithium lanthanum zirconium oxide solid electrolyte powder material. Background Technology

[0002] With the global energy structure transformation and the advancement of the "carbon neutrality" goal, the development of high-safety, high-energy-density energy storage systems has become a focus of scientific research and industrial development. All-solid-state lithium batteries are considered a key next-generation energy storage technology. Among numerous solid-state electrolyte materials, lithium lanthanum zirconium oxide (Li7La3Zr2O3) with a garnet-type crystal structure is particularly promising. 12 LLZO (Lithium-ion-ion) solid electrolytes are highly favored due to their high chemical stability to lithium metal and wide electrochemical window. However, the controllable and continuous preparation of fine-particle-size (submicron or even nanometer-scale) and highly uniform LLZO powders has become a major challenge restricting further improvement of the performance and large-scale application of all-solid-state batteries.

[0003] Currently, the mainstream route for LLZO powder preparation is the high-temperature solid-state method. However, because this method involves particle-level mixing of raw materials, the reaction occurs only at the powder interface, resulting in few nucleation points and high reaction temperatures. This can easily lead to rapid grain growth, and after calcination, the powder forms aggregates ranging from a few micrometers to tens of micrometers in size with extremely uneven particle size distribution. Therefore, achieving more thorough mixing of raw materials and reducing the high-temperature calcination temperature and time are crucial for refining LLZO powder and achieving high uniformity.

[0004] The sol-gel method for synthesizing LLZO powder involves ion-level homogeneous mixing of raw materials. During calcination, nucleation occurs simultaneously throughout the entire gel network, resulting in high and uniform nucleation density. This allows crystallization to be completed at lower temperatures, limiting grain growth and coarsening. Furthermore, laser heating offers advantages such as high energy density, fast response speed, and strong spatial controllability, enabling rapid heating and cooling of localized areas within milliseconds or even nanoseconds. Simultaneously, the flat-top laser can create a uniform temperature field, making heating more stable and controllable, and possessing the potential for continuous production. Therefore, heating sol-gel precursor powders with a flat-top laser can significantly reduce calcination time, which is beneficial for refining and homogenizing powder particle size. Summary of the Invention

[0005] This disclosure addresses the problems existing in the prior art and provides the following technical solutions:

[0006] A method for laser heating-assisted preparation of submicron-sized LALZO solid electrolyte powder materials includes the following steps:

[0007] Step S100: Prepare aluminum-doped lithium lanthanum zirconium oxide (LALZO) precursor powder by sol-gel method;

[0008] Step S200: The LALZO precursor powder is placed on a high thermal conductivity substrate, and the LALZO precursor powder is rapidly calcined using a flat-top laser to obtain submicron-sized LALZO solid electrolyte powder material.

[0009] In the method described, the sol-gel method in step S100 includes:

[0010] Step S101: Using lithium salt, lanthanum salt, zirconium salt and aluminum salt as raw materials, weigh them according to the stoichiometric ratio of aluminum-doped lithium, lanthanum, zirconium and oxygen and dissolve them in solvent;

[0011] Step S102: Add a complexing agent to the solution and stir under heating conditions to form a uniform and transparent sol-gel precursor solution;

[0012] Step S103: Dry the precursor liquid to obtain a dry gel precursor powder.

[0013] In the method described, the raw material in step S101 is selected from any one or more of carbonates, nitrates, and acetates.

[0014] In the method described, the complexing agent in step S102 is citric acid, and the molar ratio of metal ions to citric acid is approximately 1:2.

[0015] In the method described, before performing the rapid calcination process in step S200, the precursor powder needs to be sieved through a 300-mesh screen.

[0016] In the method described, the high thermal conductivity substrate in step S200 is a graphite plate or a high thermal conductivity ceramic plate.

[0017] In the method described, the heating temperature of the flat-top laser in step S200 is 900-1100℃.

[0018] In the method described, the heating power of the flat-top laser in step S200 is 3600-6000W.

[0019] In the method described, the heating time of the flat-top laser in step S200 is 1-5 minutes.

[0020] A submicron-sized LALZO solid electrolyte powder material is prepared by the laser heating-assisted preparation method for submicron-sized LALZO solid electrolyte powder material.

[0021] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0022] This disclosure provides a method for laser heating-assisted preparation of submicron-sized LALZO solid electrolyte powder materials. By utilizing laser energy, the crystallization process is shortened to the minute level, which greatly improves production efficiency and reduces energy consumption. It can effectively suppress grain growth and lithium volatilization, and obtain submicron-sized powders with an average particle size of 500-1000 nm, uniform distribution, and cubic phase structure.

[0023] The description provided is merely an overview of the technical solution disclosed herein. In order to make the technical means of this disclosure clearer and more understandable, to the point that those skilled in the art can implement it according to the contents of the specification, and in order to make the described and other objects, features and advantages of this disclosure more obvious and understandable, specific embodiments of this disclosure are illustrated below. Attached Figure Description

[0024] Various other advantages and benefits of this disclosure will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0025] Figure 1 This is a schematic diagram of a method for preparing submicron-sized LALZO solid electrolyte powder materials with laser heating assistance provided in this disclosure;

[0026] Figure 2 A schematic diagram of the apparatus for calcining garnet-type lithium lanthanum zirconium oxide solid electrolyte powder material using a flat-top laser heating method provided in this disclosure;

[0027] Figure 3 A diagram of a solid electrolyte powder material obtained in one embodiment of this disclosure;

[0028] Figure 4 This is a scanning electron microscope (SEM) image of a solid electrolyte powder material obtained in one embodiment of this disclosure;

[0029] Figure 5 XRD patterns of solid electrolyte powder materials obtained in one embodiment and one comparative example provided in this disclosure;

[0030] Figure 6 This is a scanning electron microscope (SEM) image of a solid electrolyte powder material obtained as a comparative example provided in this disclosure. Detailed Implementation

[0031] The following will be combined with the appendix Figures 1 to 6The embodiments described herein are provided in detail and are intended to explain, rather than limit, this disclosure. While specific embodiments of this disclosure are shown in the accompanying drawings, it should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0032] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions of preferred embodiments of this disclosure are for the purpose of implementing the general principles of the specification and are not intended to limit the scope of this disclosure. The scope of protection of this disclosure is determined by the appended claims.

[0033] To facilitate understanding of the embodiments of this disclosure, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of this disclosure.

[0034] A method for laser heating-assisted preparation of submicron-sized LALZO solid electrolyte powder materials, referenced Figure 1 This includes the following steps:

[0035] Step S100: Prepare aluminum-doped lithium lanthanum zirconium oxide (LALZO) precursor powder by sol-gel method;

[0036] Step S200: The LALZO precursor powder is placed on a high thermal conductivity substrate, and the LALZO precursor powder is rapidly calcined using a flat-top laser to obtain submicron-sized LALZO solid electrolyte powder material.

[0037] In a preferred embodiment of the method, the sol-gel method in step S100 includes:

[0038] Step S101: Using lithium salt, lanthanum salt, zirconium salt and aluminum salt as raw materials, weigh them according to the stoichiometric ratio of aluminum-doped lithium, lanthanum, zirconium and oxygen and dissolve them in solvent;

[0039] Furthermore, the weighing error is controlled within ±5mg, which facilitates precise control of the raw material composition.

[0040] In a preferred embodiment of the method, the raw material is selected from any one or more of carbonates, nitrates, and acetates.

[0041] Furthermore, the lithium source typically needs to be in excess by 5-20% to compensate for lithium volatilization during the high-temperature sintering process.

[0042] It should be noted that the excess lithium source must meet the following conditions: the excess lithium source needs to compensate for the volatilization of lithium at high temperatures to ensure accurate stoichiometry and stable cubic phase structure of the final product. If the amount of lithium source is too low (e.g., excess lithium source < 5%), it is easy to generate a tetragonal phase or other impurity phases with low conductivity, which will damage the electrolyte performance; if the amount of lithium source is too high (e.g., excess lithium source > 20%), it is easy to form lithium compound impurity phases, corrode the crucible, and generate heterogeneous layers.

[0043] Furthermore, Al element doping is added to stabilize the cubic phase.

[0044] Furthermore, the solvent is typically an alcohol, preferably isopropanol.

[0045] Step S102: Add a complexing agent to the solution and stir under heating conditions to form a uniform and transparent sol-gel precursor solution;

[0046] In a preferred embodiment of the method, the complexing agent in step S102 is citric acid (CA), which can undergo a complexation reaction with metal ions to prevent them from precipitating prematurely and forming a homogeneous mixed solution.

[0047] Step S103: Dry the precursor liquid to obtain a dry gel precursor powder.

[0048] The resulting mixed solution was dried at 400°C to remove the solvent and moisture, yielding a fluffy, porous dry gel LALZO precursor powder.

[0049] Step S200: The LALZO precursor powder is placed on a high thermal conductivity substrate, and the LALZO precursor powder is rapidly calcined using a flat-top laser to obtain submicron-sized LALZO solid electrolyte powder material.

[0050] In a preferred embodiment of the method, before performing the rapid calcination treatment in step S200, the precursor powder needs to be sieved through a 300-mesh screen.

[0051] In a preferred embodiment of the method, the high thermal conductivity substrate in step S200 is a graphite plate or a high thermal conductivity ceramic plate.

[0052] In one embodiment, a device reference for calcining garnet-type lithium lanthanum zirconium oxide solid electrolyte powder material using a flat-top laser heating method is provided. Figure 2 ,include:

[0053] The flat-top laser (located at the top) serves as a heating source, providing uniform and controllable laser irradiation to achieve rapid heating and cooling.

[0054] The graphite plate (located in the middle) serves as a high thermal conductivity substrate, supporting the crucible and promoting uniform heat transfer to the sample.

[0055] The crucible (placed on a graphite plate) is used to hold LALZO precursor powder. It is usually made of alumina ceramic, which is heat-resistant and chemically stable.

[0056] Infrared temperature measurement devices are used to monitor temperature changes in real time during laser heating, enabling precise temperature control.

[0057] In a preferred embodiment of the method, the heating temperature of the flat-top laser in step S200 is 900-1100°C.

[0058] It should be noted that the heating temperature of the flat-top laser must meet the following conditions: the heating temperature of the flat-top laser must ensure the formation of a cubic phase crystal structure with high ionic conductivity, while effectively suppressing excessive grain growth to obtain submicron-sized powder. If the heating temperature of the flat-top laser is too low (e.g., <900℃), the precursor cannot be completely converted into a cubic phase with high ionic conductivity, and tetragonal phase or impurity phases are easily left behind; if the heating temperature of the flat-top laser is too high (e.g., >1100℃), it will lead to excessively fast grain boundary migration rates, with some large grains rapidly engulfing small grains, resulting in larger grain sizes and severe hard agglomeration.

[0059] In a preferred embodiment of the method, the heating power of the flat-top laser in step S200 is 3600-6000W.

[0060] It should be noted that the heating power of the flat-top laser must meet the following conditions: the heating power of the flat-top laser must provide a sufficiently high energy flow to rapidly raise the precursor powder to the target temperature in a short time, while avoiding damage to the stability of the submicron structure due to local overheating or underheating. If the heating power of the flat-top laser is too low (e.g., <3600W), the heating rate will be too slow, failing to achieve the "rapid heating" effect and making it difficult to form cubic LALZO; if the heating power of the flat-top laser is too high (e.g., >6000W), the heating rate will be too fast, making it difficult to accurately control the sintering temperature, and overheating will lead to severe hard agglomeration of the powder, or even powder sublimation.

[0061] In a preferred embodiment of the method, the heating time of the flat-top laser in step S200 is 1-5 minutes.

[0062] It should be noted that the heating time of the flat-top laser must meet the following conditions: the heating time of the flat-top laser must satisfy the thermodynamic requirements for the complete crystallization of the precursor into the cubic phase, and also suppress grain growth and lithium volatilization. If the heating time of the flat-top laser is too low (e.g., <1 minute), the reaction is prone to incompleteness, resulting in amorphous residues or insufficient crystallinity in the product, thus affecting the ionic conductivity; if the heating time of the flat-top laser is too high (e.g., >5 minutes), small grains dissolve, and some large grains engulf small grains, causing the average particle size of the powder to grow to the micrometer level or even larger, resulting in obvious particle agglomeration and hardening.

[0063] A submicron-sized LALZO solid electrolyte powder material is prepared by the laser heating-assisted preparation method for submicron-sized LALZO solid electrolyte powder material, comprising:

[0064] Step S100: Prepare aluminum-doped lithium lanthanum zirconium oxide (LALZO) precursor powder by sol-gel method;

[0065] Step S200: The LALZO precursor powder is placed on a high thermal conductivity substrate, and the LALZO precursor powder is rapidly calcined using a flat-top laser to obtain submicron-sized LALZO solid electrolyte powder material.

[0066] Example: Laser heating-assisted preparation of LALZO solid electrolyte powder materials

[0067] Accurately weigh 1.0756g LiNO3, 2.5288g La(NO3)3·6H2O, 1.356g ZrO(NO3)2·xH2O, and 0.1875g Al(NO3)3·9H2O.

[0068] The above raw materials were dissolved together in 600 ml of deionized water and 700 ml of isopropanol to form a mixed solution. Then, 11.32 g of citric acid was added, and the mixture was continuously stirred at 150 °C to form a homogeneous and stable sol-gel precursor solution. The obtained sol-gel precursor solution was dried at 400 °C to remove the solvent and water, yielding a fluffy, porous dry gel precursor powder.

[0069] The dry gel precursor powder was sieved through a 300-mesh sieve and then spread evenly on an alumina crucible. The alumina crucible was placed on a graphite plate and fixed to a laser stage. The program was set to heat the material to 1000°C in 1 minute, hold for 3 minutes, close the chamber door, and then turn on the laser. The laser heating power was set to 4800W to irradiate and rapidly sinter the solid electrolyte powder material. After heating for 10 minutes, the chamber was rapidly cooled, and the obtained solid electrolyte powder material was removed.

[0070] The LALZO solid electrolyte powder material sample obtained in this embodiment is as follows: Figure 3 As shown, the sample is white and has a uniform particle size.

[0071] The SEM characterization results of the LALZO solid electrolyte powder material sample obtained in this embodiment are shown in [reference needed]. Figure 4 The sample was measured using a geometric method, and the particle size was found to be 500-1000 nm.

[0072] The XRD characterization results of the LALZO solid electrolyte powder material sample obtained in this embodiment are as follows: Figure 5 As shown, the structure conforms to the cubic phase LLZO by XRD analysis.

[0073] Comparative Example: Preparation of LALZO Solid Electrolyte Powder Materials by Traditional Sintering Method

[0074] Accurately weigh 1.0756g LiNO3, 2.5288g La(NO3)3·6H2O, 1.356g ZrO(NO3)2·xH2O and 0.1875g Al(NO3)3·9H2O.

[0075] The above raw materials were dissolved together in 600 ml of deionized water and 700 ml of isopropanol to form a mixed solution. Then, 11.32 g of citric acid was added, and the mixture was continuously stirred at 150 °C to form a homogeneous and stable sol-gel precursor solution. The obtained sol-gel precursor solution was dried at 400 °C to remove the solvent and water, yielding a fluffy, porous dry gel precursor powder.

[0076] The dry gel precursor powder was sieved through a 300-mesh sieve and then spread evenly on an alumina crucible. The alumina crucible was placed on a graphite plate and sintered in a muffle furnace at 700°C for 4 hours. After sintering, the mixture was cooled to room temperature in the furnace to obtain lithium lanthanum zirconium oxide solid electrolyte powder material prepared by conventional sintering method.

[0077] The XRD characterization results of the aluminum-doped lithium lanthanum zirconium oxide solid electrolyte powder sample obtained in this comparative example are as follows: Figure 5 As shown, XRD analysis revealed that the phase of the sample obtained by traditional muffle furnace sintering was not pure enough.

[0078] The SEM characterization results of the aluminum-doped lithium lanthanum zirconium oxide solid electrolyte powder material obtained in this comparative example are shown in [reference needed]. Figure 6 The sample was measured using a geometric method, and the particle size of the sample was calculated to be 2-38 μm, which is much larger than the particle size of solid electrolyte powder materials prepared with laser heating assistance.

[0079] Although the embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this disclosure is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the teachings of this specification and without departing from the scope of protection of the claims of this disclosure, and all of these are within the scope of protection of this disclosure.

Claims

1. A method for laser heating-assisted preparation of submicron-sized LALZO solid electrolyte powder materials, characterized in that, Includes the following steps: Step S100: Prepare aluminum-doped lithium lanthanum zirconium oxide (LALZO) precursor powder by sol-gel method; Step S200: The LALZO precursor powder is placed on a high thermal conductivity substrate, and the LALZO precursor powder is rapidly calcined using a flat-top laser to obtain submicron-sized LALZO solid electrolyte powder material.

2. The method as described in claim 1, characterized in that, Preferably, the sol-gel method in step S100 includes: Step S101: Using lithium salt, lanthanum salt, zirconium salt and aluminum salt as raw materials, weigh them according to the stoichiometric ratio of aluminum-doped lithium, lanthanum, zirconium and oxygen and dissolve them in solvent; Step S102: Add a complexing agent to the solution and stir under heating conditions to form a uniform and transparent sol-gel precursor solution; Step S103: Dry the precursor liquid to obtain a dry gel precursor powder.

3. The method as described in claim 2, characterized in that, The raw materials mentioned in step S101 are selected from any one or more of carbonates, nitrates, and acetates.

4. The method as described in claim 2, characterized in that, The complexing agent mentioned in step S102 is citric acid, and the molar ratio of metal ions to citric acid is 1:2.

2.

5. The method as described in claim 1, characterized in that, Before performing the rapid calcination treatment in step S200, the precursor powder needs to be sieved through a 300-mesh screen.

6. The method as described in claim 1, characterized in that, The high thermal conductivity substrate mentioned in step S200 is a graphite plate or a high thermal conductivity ceramic plate.

7. The method as described in claim 1, characterized in that, The heating temperature of the flat-top laser in step S200 is 900-1100℃.

8. The method as described in claim 1, characterized in that, The heating power of the flat-top laser in step S200 is 3600-6000W.

9. The method as described in claim 1, characterized in that, The heating time for the flat-top laser in step S200 is 1-5 minutes.

10. A submicron-sized LALZO solid electrolyte powder material, characterized in that, Prepared by the method described in any one of claims 1-9.

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