Latp material prepared based on organic sodium salt template method and application thereof

Abstract

The application relates to the technical field of lithium ion battery materials, and particularly discloses a method for preparing high-performance LATP material based on an organic sodium salt template method. The method uses at least one organic sodium salt, such as sodium alginate, sodium carboxymethyl cellulose or sodium polyacrylate, as a template agent, forms a three-dimensional network gel through coordination with a corresponding crosslinking agent, fixes lithium, aluminum, titanium and phosphorus source precursors in the three-dimensional network for molecular-level mixing, and obtains the LATP material after freeze-drying and step sintering. The LATP material has excellent ionic conductivity and concentrated particle size distribution, wherein sodium ions generated by the decomposition of the organic sodium salt can be doped into the crystal lattice to widen the lithium ion migration channel. When the LATP material is applied to high-nickel ternary positive electrode coating, a uniform and dense protective layer can be formed, the capacity retention rate of the battery is as high as 82.5% or more after 500 cycles at a 2C rate, and the cycle life and interface stability of the battery are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery materials technology, and in particular to an LATP material prepared based on an organic sodium salt template method and its application. Background Technology

[0002] With the increasing demand for high-energy-density power batteries in new energy vehicles, high-nickel ternary cathode materials (such as NCM811 and NCA) have become a research hotspot due to their high specific capacity. However, high-nickel ternary materials face technical bottlenecks in practical applications, such as poor interface stability, rapid cycle life decay, and poor thermal stability. These materials are prone to irreversible phase transitions during cycling and can undergo side reactions with the electrolyte, leading to a rapid decrease in capacity.

[0003] Currently, surface coating is one of the effective means to improve the performance of high-nickel ternary cathodes. Although traditional oxide coatings (such as Al2O3 and SiO2) can suppress interfacial side reactions to a certain extent, they usually have low ionic conductivity, which hinders the rapid transport of lithium ions and affects rate performance. Therefore, developing coating materials that combine high ionic conductivity and good interfacial stability has become an urgent need in the industry.

[0004] Lithium titanium aluminum phosphate (Li 1+x Al x Ti 2-x (PO4)3, abbreviated as LATP, is a solid electrolyte material with high lithium-ion conductivity and good electrochemical stability, making it an ideal candidate for ternary cathode coating materials. However, LATP materials prepared by traditional methods have the following problems: (1) Low ionic conductivity (usually ≤10). -4 (2) Wide particle size distribution (large D50 fluctuation and high content of fine / coarse powder), resulting in uneven coating; (3) Poor compatibility with the cathode material interface, and the coating layer is easy to peel off.

[0005] Patent CN115911384A discloses a modified LATP material, which forms a coating layer on the LATP surface using iron phthalocyanine, but it does not solve the problems of intrinsic ionic conductivity and particle size control. Tianjin Guoan Mengguli Company's patent application for LATP solid electrolyte (CN119750538A) uses a self-induced crystal growth method, which improves ionic conductivity, but does not address particle size distribution control or its specific application in ternary electrode coating.

[0006] Therefore, developing an LATP material that combines high ionic conductivity, narrow particle size distribution, and suitability for ternary electrode coating is of great significance for promoting the development of high-energy-density lithium-ion batteries. Summary of the Invention

[0007] Based on the technical problems existing in the background art, the present invention proposes the following technical solution: Firstly, this application provides an LATP material, wherein the general chemical formula of the LATP material is Li. 1+x Al x Ti 2-x (PO4)3, where x = 0.2~0.4; The LATP material has a NASICON-type crystal structure modified by sodium ion doping; The sodium ions in the LATP material are derived from organic sodium salts.

[0008] This application utilizes organic sodium salts to provide a sodium ion source during the sintering decomposition process, successfully achieving Na... + For Li + Partial substitution at the sites allows the larger ionic radius of sodium ions to effectively expand the lithium ion migration channels, thereby improving the ionic conductivity of LATP materials.

[0009] In some embodiments, the organic sodium salt is selected from one or more of sodium alginate, sodium carboxymethyl cellulose, sodium polyacrylate, sodium citrate, sodium dodecyl phosphate, sodium gluconate, sodium hydroxypropyl methyl cellulose, and sodium carboxymethyl starch; and / or The particle size distribution of the LATP material satisfies the following conditions: D50 is 0.95~1.10μm, and the distribution width Span is 0.5~0.9.

[0010] The molecular chains of organic sodium salts form a stable three-dimensional network structure through cross-linking of calcium or aluminum ions. This "template effect" works synergistically with the sodium ion doping strategy, which not only optimizes the particle size distribution of the material, but also significantly improves the dispersibility and interfacial compatibility of the material in ternary cathode slurry.

[0011] Secondly, this application provides a method for preparing the LATP material, the method comprising the following steps: S1: The lithium source, aluminum source, titanium source, and phosphorus source are arranged according to Li... 1+x Al x Ti 2-x The inorganic precursor is obtained by mixing (PO4)3 in stoichiometric proportions, where x = 0.2~0.4. The inorganic precursor is then mixed with an aqueous solution of an organic sodium salt to form a homogeneous slurry. S2: Add a crosslinking agent to the slurry, and a three-dimensional network gel is formed after the reaction. The three-dimensional network gel is then subjected to vacuum freeze-drying to obtain a porous dry gel precursor. S3: The porous dry gel precursor is subjected to a step-by-step sintering process, and after crushing and sieving, the LATP material is obtained.

[0012] This invention utilizes organic sodium salt molecular chains to form a stable three-dimensional network structure through cross-linking, immobilizing the precursor within the network for molecular-level mixing. This optimizes the material's particle size distribution and provides a uniform precursor base for subsequent sodium ion doping. The biotemplative agent used in this invention is environmentally friendly, and the process route is simple, offering a new technical pathway for the development of high-performance solid-state electrolyte materials.

[0013] In some implementations, step S1 satisfies at least one of the following conditions (1) to (7): (1) The lithium source is selected from one or more of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide and lithium chloride; (2) The aluminum source is selected from one or more of aluminum hydroxide, aluminum nitrate, aluminum isopropoxide, aluminum acetylacetone, aluminum chloride, and aluminum oxide; (3) The titanium source is selected from one or more of tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride and titanium dioxide; (4) The phosphorus source is selected from one or more of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid, and triethyl phosphate; (5) The organic sodium salt is selected from sodium alginate, sodium carboxymethyl cellulose, or sodium polyacrylate; (6) The amount of the organic sodium salt added is 3% to 8% of the total mass of the inorganic precursor; or (7) The mixing speed is 2000-10000 rpm, the temperature is 25~35℃, and the time is 30~120 min.

[0014] By selecting specific raw materials and their amounts, it is possible to ensure that the precursor is uniformly dispersed in the gel network, promoting molecular-level mixing and laying the foundation for the subsequent formation of high-performance LATP materials.

[0015] In some implementations, step S2 satisfies at least one of the following conditions (8) to (12): (8) The crosslinking agent is selected from calcium ion crosslinking agents or aluminum ion crosslinking agents; (9) The concentration of the crosslinking agent is 0.5wt%~2wt%; (10) The calcium ion crosslinking agent is selected from calcium chloride, calcium gluconate, calcium acetate or calcium nitrate; (11) The aluminum ion crosslinking agent is selected from aluminum chloride, aluminum sulfate, aluminum nitrate, or aluminum isopropoxide; or (12) The vacuum degree of the vacuum freeze drying is 1-10 Pa, the temperature is -100~-50℃, and the time is 24~72h.

[0016] By using crosslinking agents of appropriate concentration and type, a stable three-dimensional network structure can be formed with organic sodium salts, ensuring uniform fixation of the precursor, avoiding agglomeration, and improving the consistency and electrochemical performance of the material.

[0017] In some embodiments, the combination of the organic sodium salt and the crosslinking agent is sodium alginate or sodium carboxymethyl cellulose, combined with a calcium ion crosslinking agent; or A combination of sodium polyacrylate and aluminum ion crosslinking agent.

[0018] A specific combination of crosslinking systems can form a stable three-dimensional network gel, avoiding the uneven gel structure caused by the mismatch between the crosslinking agent and the template agent, and ensuring that the material has a concentrated particle size distribution and stable ionic conductivity.

[0019] In some implementations, the step-by-step sintering process in step S3 is as follows: first, hold at 200~300℃ for 1~3 hours, then hold at 400~500℃ for 1~3 hours, and finally crystallize at 850~950℃ for 3~6 hours.

[0020] The stepped sintering process can gradually remove the template agent and promote the formation of crystal phase, effectively control grain growth, obtain LATP materials with uniform particle size distribution and high crystallinity, and improve ionic conductivity.

[0021] Thirdly, this application provides an LATP material prepared by the method described above.

[0022] The LATP material possesses high ionic conductivity, concentrated particle size distribution, and good interfacial compatibility with cathode materials.

[0023] Fourthly, this application provides the application of the LATP material or the LATP material prepared by the method described above in the preparation of positive electrode active materials.

[0024] Applying the LATP material to the coating of high-nickel ternary cathode sheets creates a continuous three-dimensional ion-conducting network inside the electrode, significantly improving the cycle life and interface stability of the battery.

[0025] Fifthly, this application provides a battery, the battery comprising a positive electrode, a negative electrode, and an electrolyte; The positive electrode sheet includes the LATP material or the LATP material prepared by the method.

[0026] Batteries containing the LATP material exhibit excellent cycle performance, retaining a capacity of over 82.5% after 500 cycles at 2C rate. Attached Figure Description

[0027] Figure 1 The XRD patterns are those of Example 1 and Comparative Example 1.

[0028] Figure 2 The image shown is the XRD pattern of Example 2. Detailed Implementation

[0029] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0030] For the sake of brevity, this document only discloses a few specific numerical ranges for a given parameter. However, any lower limit can be combined with any upper limit to form an unspecified range, and any lower limit can be combined with other lower limits to form an unspecified range; similarly, any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit, combined with any other point or single value, or with other lower or upper limits, to form an unspecified range. It should be understood that this disclosure is not limited to the specific methods, schemes, and reagents described herein, and is itself subject to variation. The terminology used herein is for the purpose of describing specific embodiments or aspects only and is not intended to limit the scope of this disclosure.

[0031] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application). Unless otherwise expressly stated, all reagents used in this application are commonly used reagents for chemical analysis or experiments and are derived from conventional commercial suppliers in the art.

[0032] The list of items connected by the terms "at least one of," "at least one of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single component or multiple components. Item B may contain a single component or multiple components. Item C may contain a single component or multiple components.

[0033] In this article, "LATP (lithium aluminum titanium phosphate)" refers to a lithium-ion solid electrolyte with a NASICON-type structure, whose general chemical formula is Li. 1+x Al x Ti 2-x (PO4)3, where x = 0.2~0.4.

[0034] In this paper, "sodium ion doping" refers to the introduction of sodium ions during the material preparation process, which partially replace lithium ion sites in the LATP lattice, thereby expanding the lithium ion migration channels and improving the ionic conductivity of the material.

[0035] In this paper, "D50" refers to the particle size at which the cumulative volume distribution of material particles reaches 50%, and the unit is micrometers (μm), which is used to characterize the average particle size of the material.

[0036] In this paper, the “Span value” represents the width of the particle size distribution. The calculation formula is Span=(D90-D10) / D50. The smaller the value, the more concentrated the particle size distribution.

[0037] In this paper, the "organic sodium salt template method" refers to a preparation method in which organic sodium salt is used as a structure directing agent in the material preparation process. Through cross-linking, a three-dimensional network structure is formed, and inorganic precursors are fixed in the network to achieve molecular-level mixing and control the morphology and particle size of the material.

[0038] In this document, "crosslinking agent" refers to a substance capable of undergoing ionic crosslinking reaction with the functional groups on the molecular chain of organic sodium salt. In this application, it is a calcium ion crosslinking agent or an aluminum ion crosslinking agent, used to form a three-dimensional network gel.

[0039] In this paper, "inorganic precursor" refers to an unsintered mixture obtained by mixing lithium, aluminum, titanium and phosphorus sources in stoichiometric proportions, which is used to subsequently combine with an organic sodium salt template system to prepare LATP materials.

[0040] Example 1 The synthesis steps of the LATP material in this embodiment are as follows: S1, Press Li 1.2 Al 0.2 Ti 1.8 Weigh 100g of the inorganic precursor (PO4)3 according to the stoichiometric ratio. The inorganic precursor contains 8.1g of lithium carbonate, 26.2g of titanium dioxide, 2.8g of aluminum hydroxide, and 62.9g of ammonium dihydrogen phosphate. Mix it with 3g of sodium alginate dissolved in 200mL of deionized water as a template agent. Perform high-speed shear emulsification at 10000rpm and 25℃ for 30min to form a uniform slurry.

[0041] S2. Add 50 mL of 0.5 wt% calcium chloride aqueous solution as a crosslinking agent to the slurry prepared in step S1 and let it stand at room temperature for 12 hours to gel. The gelled three-dimensional network gel is first pre-frozen at -40℃ and then vacuum freeze-dried at -50℃ for 24 hours under vacuum conditions of ≤10 Pa to obtain the dry gel precursor.

[0042] S3. The dry gel precursor prepared in step S2 was subjected to stepwise sintering: first, it was held at 200℃ for 3 hours, then at 400℃ for 3 hours, and finally crystallized at 850℃ for 6 hours to obtain the sintered product. The sintered product was ball-milled at 200 rpm for 30 min at room temperature. After sieving, LATP powder with D50=1.05μm and Span=0.88 was obtained, with an ionic conductivity of 9.2×10⁻⁶. -4 S / cm. After applying LATP powder to NCM811 electrode coating, a positive electrode is obtained. The positive electrode is then used in the preparation of a battery. The resulting battery retains 82.5% of its capacity after 500 cycles at 2C rate.

[0043] Example 2 The synthesis steps of the LATP material in this embodiment are as follows: S1, Press Li 1.4 Al 0.4 Ti 1.6 100g of an inorganic precursor, comprising 15.2g of lithium nitrate, 48.5g of tetrabutyl titanate, 11.9g of aluminum nitrate, and 24.4g of phosphoric acid, was weighed out according to the stoichiometric ratio of (PO4)3. This precursor was mixed with 5g of sodium carboxymethyl cellulose dissolved in 200mL of deionized water as a template agent. The mixture was then subjected to high-speed shear emulsification at 10000rpm and 25℃ for 30min to form a uniform slurry.

[0044] S2. Add 50 mL of 1 wt% calcium chloride aqueous solution as a crosslinking agent to the slurry prepared in step S1 and let it stand at room temperature for 12 hours to gel. The gelled three-dimensional network gel is first pre-frozen at -40℃ and then vacuum freeze-dried at -50℃ for 24 hours under vacuum conditions of ≤10Pa to obtain the dry gel precursor.

[0045] S3. The dry gel precursor prepared in step S2 is subjected to stepwise sintering: first, it is held at 250℃ for 2 hours, then at 450℃ for 2 hours, and finally crystallized at 880℃ for 4 hours to obtain the sintered product. The sintered product is ball-milled at 200 rpm for 30 min at room temperature. After sieving, LATP powder with D50=0.96μm and Span=0.52 is obtained, and its ionic conductivity reaches 1.05×10⁻⁶. -3 S / cm. After applying LATP powder to NCM811 electrode coating, a positive electrode is obtained. The positive electrode is then used in the preparation of a battery. The resulting battery retains 84.5% of its capacity after 500 cycles at 2C rate.

[0046] Example 3 The synthesis steps of the LATP material in this embodiment are as follows: S1, Press Li 1.3 Al 0.3 Ti 1.7 Weigh 100g of the inorganic precursor (PO4)3 according to the stoichiometric ratio. The inorganic precursor contains 8.7g of lithium carbonate, 24.6g of titanium dioxide, 4.2g of aluminum hydroxide, and 62.5g of ammonium dihydrogen phosphate. Mix it with 4g of sodium polyacrylate dissolved in 200mL of deionized water as a template agent. Perform high-speed shear emulsification at 10000rpm and 25℃ for 30min to form a uniform slurry.

[0047] S2. Add 50 mL of 1 wt% aluminum chloride aqueous solution as a crosslinking agent to the slurry prepared in step S1 and let it stand at room temperature for 24 hours to gel. The gelled three-dimensional network gel is first pre-frozen at -40℃ and then vacuum freeze-dried at -50℃ for 24 hours under vacuum conditions of ≤10Pa to obtain the dry gel precursor.

[0048] S3. The dry gel precursor prepared in step S2 was subjected to stepwise sintering: first, it was held at 250℃ for 2 hours, then at 450℃ for 2 hours, and finally crystallized at 900℃ for 4 hours to obtain the sintered product. The sintered product was ball-milled at 200 rpm for 30 min at room temperature. After sieving, LATP powder with D50=1.02μm and Span=0.61 was obtained, with an ionic conductivity of 9.8×10⁻⁶. -4 S / cm. After applying LATP powder to NCM811 electrode coating, a positive electrode is obtained. The positive electrode is then used in the preparation of a battery. The resulting battery retains 83.8% of its capacity after 500 cycles at 2C rate.

[0049] Example 4 The synthesis steps of the LATP material in this embodiment are as follows: S1, Press Li 1.25 Al 0.25 Ti 1.75 100g of an inorganic precursor containing 6.3g lithium hydroxide, 29.4g titanium dioxide, 2.7g aluminum oxide, and 61.6g phosphoric acid was weighed out according to the stoichiometric ratio of (PO4)3. This precursor was mixed with 6g of sodium alginate dissolved in 200mL of deionized water as a template agent. The mixture was then subjected to high-speed shear emulsification at 10000rpm and 25℃ for 30min to form a uniform slurry.

[0050] S2. Add 50 mL of 1.5 wt% calcium chloride aqueous solution as a crosslinking agent to the slurry prepared in step S1 and let it stand at room temperature for 12 hours to gel. The gelled three-dimensional network gel is first pre-frozen at -40℃ and then vacuum freeze-dried at -50℃ for 24 hours under vacuum conditions of ≤10 Pa to obtain the dry gel precursor.

[0051] S3. The dry gel precursor prepared in step S2 was subjected to stepwise sintering: first, it was held at 280℃ for 1.5 hours, then at 480℃ for 1.5 hours, and finally crystallized at 880℃ for 5 hours to obtain the sintered product. The sintered product was ball-milled at 200 rpm for 30 minutes at room temperature. After sieving, LATP powder with D50=0.99μm and Span=0.58 was obtained, with an ionic conductivity of 1.02×10⁻⁶. -3 S / cm. After applying LATP powder to NCM811 electrode coating, a positive electrode is obtained. The positive electrode is then used in the preparation of a battery. The resulting battery retains 84.2% of its capacity after 500 cycles at 2C rate.

[0052] Example 5 The synthesis steps of the LATP material in this embodiment are as follows: S1, Press Li 1.35 Al 0.35 Ti 1.65 Weigh 100g of the inorganic precursor (PO4)3 according to the stoichiometric ratio. The inorganic precursor contains 8.0g of lithium chloride, 43.5g of titanium tetrachloride, 6.5g of aluminum chloride, and 42.0g of phosphoric acid. Mix it with 4g of sodium alginate dissolved in 200mL of deionized water as a template agent. Perform high-speed shear emulsification at 10000rpm and 25℃ for 30min to form a uniform slurry.

[0053] S2. Add 50 mL of 1.2 wt% calcium chloride aqueous solution as a crosslinking agent to the slurry prepared in step S1 and let it stand at room temperature for 12 hours to gel. The gelled three-dimensional network gel is first pre-frozen at -40℃ and then vacuum freeze-dried at -50℃ for 24 hours under vacuum conditions of ≤10Pa to obtain the dry gel precursor.

[0054] S3. The dry gel precursor prepared in step S2 was subjected to stepwise sintering: first, it was held at 260℃ for 2 hours, then at 420℃ for 2 hours, and finally crystallized at 920℃ for 4 hours to obtain the sintered product. The sintered product was ball-milled at 200 rpm for 30 min at room temperature. After sieving, LATP powder with D50=1.05μm and Span=0.65 was obtained, with an ionic conductivity of 9.5×10⁻⁶. -4S / cm. After applying LATP powder to NCM811 electrode coating, a positive electrode is obtained. The positive electrode is then used in the preparation of a battery. The resulting battery retains 83.6% of its capacity after 500 cycles at 2C rate.

[0055] Comparative Example 1 The synthesis steps of the LATP material in this comparative example are as follows: S1, Press Li 1.3 Al 0.3 Ti 1.7 100g of an inorganic precursor containing 8.7g of lithium carbonate, 24.6g of titanium dioxide, 4.2g of aluminum hydroxide, and 62.5g of ammonium dihydrogen phosphate was weighed out according to the stoichiometric ratio of (PO4)3 and mechanically mixed to obtain a mixture.

[0056] S2. The mixture prepared in step S1 is sintered at 900°C for 4 hours without gelation and freeze-drying steps to obtain the sintered product.

[0057] S3. The sintered product obtained in step S2 was ball-milled at 200 rpm for 30 min at room temperature to obtain LATP powder with D50 = 2.50 μm and Span = 1.85, and its ionic conductivity was 3.0 × 10⁻⁶. -4 S / cm. After coating NCM811 electrode with LATP powder, a positive electrode was obtained. The positive electrode was then used in the preparation of a battery. The resulting battery retained 65.8% of its capacity after 500 cycles at 2C rate.

[0058] Comparative Example 2 The synthesis steps of the LATP material in this comparative example are as follows: S1, Press Li 1.3 Al 0.3 Ti 1.7 Weigh 100g of the inorganic precursor (PO4)3 according to the stoichiometric ratio. The inorganic precursor contains 8.7g of lithium carbonate, 24.6g of titanium dioxide, 4.2g of aluminum hydroxide, and 62.5g of ammonium dihydrogen phosphate. Mix it with 4g of sodium alginate dissolved in 200mL of deionized water as a template agent. Perform high-speed shear emulsification at 10000rpm and 25℃ for 30min to form a uniform slurry.

[0059] S2. The uniform slurry prepared in step S1 is dried at 150°C for 10 hours to obtain the precursor.

[0060] S3. The precursor obtained in step S2 is subjected to stepwise sintering: first, it is held at 250℃ for 2 hours, then at 450℃ for 2 hours, and finally crystallized at 900℃ for 4 hours to obtain the sintered product. The sintered product is ball-milled at 200 rpm for 30 min at room temperature. After sieving, LATP powder with D50=1.25μm and Span=1.25 is obtained, and its ionic conductivity is 6.5×10⁻⁶. -4 S / cm. After applying LATP powder to NCM811 electrode coating, a positive electrode is obtained. The positive electrode is then used in the preparation of a battery. The resulting battery retains 75.3% of its capacity after 500 cycles at 2C rate.

[0061] Comparative Example 3 The synthesis steps of the LATP material in this comparative example are as follows: S1, Press Li 1.3 Al 0.3 Ti 1.7 Weigh 100g of the inorganic precursor (PO4)3 according to the stoichiometric ratio. The inorganic precursor contains 8.7g of lithium carbonate, 24.6g of titanium dioxide, 4.2g of aluminum hydroxide, and 62.5g of ammonium dihydrogen phosphate. Mix it with 4g of sodium alginate dissolved in 200mL of deionized water as a template agent. Perform high-speed shear emulsification at 10000rpm and 25℃ for 30min to form a uniform slurry.

[0062] S2. Add 50 mL of 1 wt% aluminum chloride aqueous solution as a crosslinking agent to the slurry prepared in step S1 and let it stand at room temperature for 24 hours to gel. The gelled three-dimensional network gel is first pre-frozen at -40℃ and then vacuum freeze-dried at -50℃ under vacuum conditions of ≤10Pa to obtain a dry gel precursor.

[0063] S3. The dry gel precursor prepared in step S2 was directly subjected to single-stage sintering: the temperature was maintained at 850℃ for 4 hours to obtain the sintered product. The sintered product was then ball-milled at 200 rpm for 30 minutes at room temperature. After sieving, LATP powder with D50=1.35μm and Span=1.32 was obtained, with an ionic conductivity of 7.2×10⁻⁶. -4 S / cm. After coating NCM811 electrode with LATP powder, a positive electrode was obtained. The positive electrode was then used in the preparation of a battery. The resulting battery retained 77.8% of its capacity after 500 cycles at 2C rate.

[0064] Comparative Example 4 (Non-sodium salt template agent: PEG system) The difference between the LATP material in this comparative example and that in Example 2 is that only polyethylene glycol (PEG-400) was used as a template agent, without the addition of any organic sodium salts, and the amount of PEG-400 used was 5g. The types and amounts of other raw materials and experimental procedures were the same as in Example 2. The ionic conductivity, Span value, and capacity retention of the LATP after 500 cycles at 2C are shown in Table 1.

[0065] Comparative Example 5 (Non-sodium salt template agent: PVP system) The difference between the LATP material in this comparative example and that in Example 2 is that only polyvinylpyrrolidone (PVP) was used as a template agent, and no organic sodium salts were added. The types and amounts of other raw materials and experimental procedures were the same as in Example 2. The ionic conductivity, Span value, and capacity retention of the LATP after 500 cycles at 2C are shown in Table 1.

[0066] Comparative Example 6 (Crosslinking agent and template agent combination: sodium polyacrylate + calcium ions) The LATP material in this comparative example differs from that in Example 3 in that sodium polyacrylate is used as the template agent, but calcium chloride is used as the crosslinking agent. The types and amounts of other raw materials, as well as the experimental procedures, are the same as in Example 3. The ionic conductivity, Span value, and capacity retention of the LATP battery after 500 cycles at 2C are shown in Table 1.

[0067] Comparative Example 7 (Organic Magnesium Salt Template Agent: Magnesium Citrate System) The difference between the LATP material in this comparative example and Example 1 is that magnesium citrate (organic magnesium salt) was used instead of sodium alginate as a template agent to compare the effect of magnesium ion doping. The types and amounts of other raw materials and experimental procedures were the same as in Example 1. The ionic conductivity, Span value, and capacity retention of the LATP battery after 500 cycles at 2C rate are shown in Table 1.

[0068] Comparative Example 8 (Organic Calcium Salt Template Agent: Calcium Gluconate System) The difference between the LATP material in this comparative example and Example 1 is that calcium gluconate (organic calcium salt) was used instead of sodium alginate as the template agent to compare the calcium ion doping effect. The types and amounts of other raw materials and experimental procedures were the same as in Example 1. The ionic conductivity, Span value, and capacity retention of the LATP battery after 500 cycles at 2C are shown in Table 1.

[0069] Performance testing of LATP materials, battery fabrication and performance testing (1) D10, D50 and D90 tests of LATP materials: The particle size of the LATP materials prepared in Examples 1-5 and Comparative Examples 1-8 was tested using a Malvern 3000 laser particle size analyzer. The formula for calculating the distribution width (Span) is: Span value = (D90 - D10) / D50.

[0070] (2) Ionic conductivity test of LATP material: AC impedance spectroscopy was used for testing: The LATP materials prepared in Examples 1-5 and Comparative Examples 1-8 were pressed into tablets (300 MPa, 100 s) using a tablet press, sintered at 900 °C to form ceramic sheets, and the surfaces of the ceramic sheets were polished and gold-plated. Then, using an electrochemical workstation, an AC input signal of 5 mV and a impedance of 0.1~10 μV were applied in air. 6 The frequency range of Hz was measured at a temperature of 25℃ and calculated using the formula σ=L / (RS).

[0071] (3) Battery fabrication: The LATP materials prepared in Examples 1-5 and Comparative Examples 1-8 were mixed with the binder polyvinylidene fluoride at a ratio of 9:1, and N-methylpyrrolidone was added to achieve a solid content of 25-30% and the mixture was uniformly mixed. The mixture was coated on NCM811 electrode sheets with a thickness of 4 μm, dried, rolled and compacted, and cut into electrode sheets for later use. Using lithium metal as the counter electrode and 1M LiPF6 as the electrolyte, a coin cell was assembled.

[0072] (4) Battery cycle performance test: Tests were conducted within a voltage range of 2.5–4.45 V. Cycle stability testing was performed at a constant charge-discharge rate of 2C, and capacity retention was recorded after 500 cycles.

[0073] (5) X-ray diffraction (XRD) testing method: The scanning range was 2θ = 10° to 80°, and the scanning speed was 2° / min. The LATP materials prepared by Comparative Example 1 (conventional solid-state method), Example 1 (sodium alginate template method), and Example 2 (sodium carboxymethyl cellulose template method) were subjected to phase analysis.

[0074] Table 1 shows the ionic conductivity, distribution width, and capacity retention of the LATP material after 500 battery cycles.

[0075] Table 1. Ionic conductivity, distribution width, and electrical performance test results of the LATP materials prepared in each embodiment and comparative example, as well as the batteries prepared by incorporating the cathode material.

[0076] As can be seen from Table 1, the LATP material prepared using this invention achieves a maximum ionic conductivity of 1.05 × 10⁻⁶. -3 S / cm, when applied to ternary electrode coating, the battery retains 84.5% capacity after 500 cycles at 2C rate, as shown in Example 2. The XRD pattern of the LATP material in Example 2 is as follows. Figure 2 As shown, this fully demonstrates that organic sodium salts achieve molecular-level mixing of precursors during the preparation process by forming a gel structure; at the same time, the sodium ion doping effect generated by its pyrolysis effectively improves the particle size distribution and ion transport performance of the material, significantly enhancing the cycle stability of the battery.

[0077] The XRD patterns of Example 1 and Comparative Example 1 are as follows: Figure 1 As shown in the figure. Although the characteristic peaks of the LATP main phase appeared in Comparative Example 1, obvious TiO2 and AlPO4 impurity phase peaks were detected at 2θ=27.5° and 22.6°, indicating that the reaction was incomplete due to uneven mixing of raw materials in the traditional solid-phase method.

[0078] In contrast, the XRD pattern of Example 1 was completely consistent with the NASICON-type LATP standard card (JCPDS No. 35-0754), and no impurity peaks were detected. Further comparison revealed that all diffraction peaks in Example 1 shifted towards smaller angles compared to Comparative Example 1. This shift in peak position indicates an increase in the interplanar spacing d, which is due to the Na+ produced by the pyrolysis of sodium alginate. + (Radius 102 pm) Partially replaces Li + The sodium ion (76 pm radius) enters the crystal lattice, causing lattice expansion. This result confirms that the method of the present invention not only improves the phase purity of the material, but also successfully achieves sodium ion doping.

[0079] The embodiments described in this application are merely illustrative examples. The embodiments of this application are not limited to the above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of this application shall be considered equivalent substitutions and shall be included within the protection scope of this application.

Claims

1. An LATP material, characterized in that, The general chemical formula of the LATP material is Li 1+x Al x Ti 2-x (PO4)3, wherein x = 0.2-0.4; The LATP material has a NASICON-type crystal structure modified by sodium ion doping; The sodium ions in the LATP material are derived from organic sodium salts.

2. The LATP material as described in claim 1, characterized in that, The organic sodium salt is selected from one or more of sodium alginate, sodium carboxymethyl cellulose, sodium polyacrylate, sodium citrate, sodium dodecyl phosphate, sodium gluconate, sodium hydroxypropyl methyl cellulose, and sodium carboxymethyl starch; and / or The particle size distribution of the LATP material satisfies the following conditions: D50 is 0.95~1.10μm, and the distribution width Span is 0.5~0.

9.

3. A method for preparing the LATP material as described in claim 1 or 2, characterized in that, The method includes the following steps: S1: The lithium source, aluminum source, titanium source, and phosphorus source are arranged according to Li... 1+x Al x Ti 2-x The inorganic precursor is obtained by mixing (PO4)3 in stoichiometric proportions, where x = 0.2~0.

4. The inorganic precursor is then mixed with an aqueous solution of an organic sodium salt to form a homogeneous slurry. S2: Add a crosslinking agent to the slurry, and a three-dimensional network gel is formed after the reaction. The three-dimensional network gel is then subjected to vacuum freeze-drying to obtain a porous dry gel precursor. S3: The porous dry gel precursor is subjected to a step-by-step sintering process, and after crushing and sieving, the LATP material is obtained.

4. The method as described in claim 3, characterized in that, Step S1 satisfies at least one of the following conditions (1) to (7): (1) The lithium source is selected from one or more of lithium carbonate, lithium nitrate, lithium acetate, lithium hydroxide and lithium chloride; (2) The aluminum source is selected from one or more of aluminum hydroxide, aluminum nitrate, aluminum isopropoxide, aluminum acetylacetone, aluminum chloride, and aluminum oxide; (3) The titanium source is selected from one or more of tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride and titanium dioxide; (4) The phosphorus source is selected from one or more of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, phosphoric acid, and triethyl phosphate; (5) The organic sodium salt is selected from sodium alginate, sodium carboxymethyl cellulose, or sodium polyacrylate; (6) The amount of the organic sodium salt added is 3% to 8% of the total mass of the inorganic precursor; or (7) The mixing speed is 2000-10000 rpm, the temperature is 25~35℃, and the time is 30~120 min.

5. The method as described in claim 3, characterized in that, Step S2 satisfies at least one of the following conditions (8) to (12): (8) The crosslinking agent is selected from calcium ion crosslinking agents or aluminum ion crosslinking agents; (9) The concentration of the crosslinking agent is 0.5wt%~2wt%; (10) The calcium ion crosslinking agent is selected from calcium chloride, calcium gluconate, calcium acetate or calcium nitrate; (11) The aluminum ion crosslinking agent is selected from aluminum chloride, aluminum sulfate, aluminum nitrate, or aluminum isopropoxide; or (12) The vacuum degree of the vacuum freeze drying is 1-10 Pa, the temperature is -100~-50℃, and the time is 24~72h.

6. The method as described in claim 3, characterized in that, The combination of the organic sodium salt and the crosslinking agent is a combination of sodium alginate or sodium carboxymethyl cellulose and a calcium ion crosslinking agent; or A combination of sodium polyacrylate and aluminum ion crosslinking agent.

7. The method as described in claim 3, characterized in that, The procedure for the stepped sintering process in step S3 is as follows: first, hold at 200~300℃ for 1~3 hours, then hold at 400~500℃ for 1~3 hours, and finally crystallize at 850~950℃ for 3~6 hours.

8. An LATP material prepared by the method according to any one of claims 3-7.

9. The LATP material according to claim 1, 2 or 8, or the LATP material prepared by any of the methods described in claims 3-7, in the preparation of positive electrode active materials.

10. A battery, characterized in that, The battery includes a positive electrode, a negative electrode, and an electrolyte; The positive electrode sheet includes the LATP material as described in claim 1, 2 or 8, or the LATP material prepared by any of the methods described in claims 3-7.

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