Nano-carbon composite titanium aluminum lithium phosphate conductive functional material and preparation process and application thereof

Abstract

The invention provides a nano-carbon composite titanium aluminum lithium phosphate conductive functional material and a preparation process and application thereof, and the process adopts a mode of adding synthetic components step by step, so that the reaction is performed according to preset selectivity; according to the method, the mixing uniformity is improved, the reaction rate is controlled, the utilization rate of raw materials is improved, large-scale production and application can be achieved without complex process control, and the nanocrystallized lithium titanium aluminum phosphate conductive functional material of the in-situ composite carbon layer is synthesized under inert gas, so that the nanocrystallized lithium titanium aluminum phosphate conductive functional material is not limited to the range of being independently used as a solid electrolyte; carbon composite nanocrystallization modification endows electronic insulation titanium aluminum lithium phosphate with high electronic conductivity, the prepared nanocarbon composite titanium aluminum lithium phosphate conductive functional material and slurry thereof can be used as a modified material of a lithium ion battery and a solid or semi-solid battery electrode material, surface activity of the electrode material is passivated, side reaction of a battery material interface is reduced, and the service life of the battery is prolonged. Structural degeneration of the material in circulation is slowed down, and the overall safety of the lithium ion battery is enhanced.

Description

Technical Field

[0001] The invention relates to a nano-carbon composite lithium titanium aluminum phosphate conductive functional material and a preparation process and application thereof, belonging to the technical field of conductive functional materials for lithium ion batteries and solid or semi-solid electrolyte electrode modification. Background Art

[0002] Compared with traditional electrochemical batteries such as lead-acid, nickel-cadmium, and zinc-manganese batteries, lithium-ion batteries have many advantages such as high energy density, light weight, no memory effect, and green environmental protection. They are widely used in 3C electronics, electric vehicles, and national defense and military industries. During the charging and discharging process, lithium ions in existing lithium-ion batteries are repeatedly embedded and deintercalated between the positive and negative electrodes, electrolytes, electrolytes, and diaphragms inside the battery. The valence state changes of transition metals and other variable valence elements provide electrons to the outside of the lithium-ion battery to realize the working cycle of lithium-ion battery charging and discharging, commonly known as "rocking chair batteries". At present, lithium-ion batteries generally use organic liquid electrolytes and electrolyte systems. During the charging and discharging process, liquid electrolytes and electrolytes inevitably react with electrode materials and additives to a certain extent. In particular, during the process of battery loss of control, liquid electrolytes and electrolytes are easily decomposed to produce toxic and harmful gases. They are highly volatile and have weak impact resistance, which affects the cycle life of lithium-ion batteries and has the risk of leakage, which is easy to cause safety hazards. Developing all-solid-state or semi-solid-state lithium batteries and optimizing and improving lithium secondary batteries are effective ways to resolve safety accidents caused by liquid electrolyte systems. Therefore, related technologies have become a hot topic in research in this field.

[0003] At present, solid electrolytes can be divided into several categories, such as inorganic oxides, organic polymers PEO, sulfides and halides. Sulfides and halides have high ionic conductivity, but the preparation process is complex, the cost is high, and the air stability is poor; organic polymers such as PEO have good processing performance and low cost, but the room temperature ionic conductivity is low; inorganic oxide solid electrolytes have attracted much attention due to their wide synthesis conditions, ionic conductivity, excellent electrochemistry and air stability. Common inorganic oxides include NASICON lithium aluminum titanium phosphate (LATP), garnet lithium lanthanum zirconate (LLZO), perovskite lithium lanthanum titanate (LLTO), etc. At present, there are many methods for synthesizing oxide solid electrolytes, mainly concentrated in sol-gel method, high-temperature solid phase method, coprecipitation method, etc. Among these methods, the high-temperature solid phase method has low cost and is easy to scale up, but it is difficult to control the product consistency of the prepared materials; the chemical coprecipitation method has high requirements for precipitation rate and process pH control; the sol-gel method can be uniformly mixed at the molecular level, greatly reducing the ion migration path, can effectively reduce the sintering temperature and energy consumption of the crystallization process, and is easy to achieve material nano-sizing. At present, technical solutions such as patent announcement numbers CN115403022A and CN105680090 have successfully achieved the nano-sizing preparation of oxide solid electrolytes LATP, but the solid electrolytes synthesized by the existing technical solutions cannot be used as electronic conductive functional materials to achieve effective electronic conductivity, thereby affecting its effect as a functional material in the modification of lithium ion battery materials, which is not conducive to the overall performance of the battery; and carbon composite nano-sized oxide lithium titanium aluminum phosphate as a composite particle conductive functional material, the expansion of application and its process preparation method in lithium ion secondary batteries are rarely reported. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention proposes a nano-carbon composite lithium titanium aluminum phosphate conductive functional material and its preparation process and application. The nano-carbon composite lithium titanium aluminum phosphate conductive functional material can be used as an ion and electron conductive functional material in the modification of lithium-ion batteries, solid or semi-solid battery electrode materials and auxiliary materials for application expansion.

[0005] The technical solution of the present invention is a preparation process of a nano-carbon composite lithium aluminum titanium phosphate conductive functional material, the molecular formula of which is Li 1+x Al x Ti 2-x (PO4)3-C y , x=0.25-0.45, y=0.2-1.5, and the preparation process comprises the following steps:

[0006] Step 1. dispersing a lithium source into an organic solvent to obtain a slurry A;

[0007] Step 2. Continue to disperse the aluminum source into the A slurry to obtain the B slurry;

[0008] Step 3. dispersing the organic titanium source into the B slurry to obtain the C slurry;

[0009] Step 4. dissolving the carbon source in the phosphorus source water to obtain a D solution;

[0010] Step 5. Slowly add the D solution into the stirred C slurry to hydrolyze the organic titanium source slowly while uniformly dispersing the carbon source and phosphorus source in the D solution to obtain the LATP-C conductive functional material precursor sol slurry;

[0011] Step 6. After the nano-LATP-C conductive functional material precursor sol slurry is dried by microwave or hot air to remove water and organic volatiles, it is calcined under the protection of an inert gas such as nitrogen or argon, and crushed to obtain the nano-LATP-C conductive functional material.

[0012] In the above process, the organic solvent is one or more of anhydrous ethanol, isopropanol and acetic acid.

[0013] In the above process, the phosphorus source is one or more of ammonium dihydrogen phosphate, lithium dihydrogen phosphate and phosphoric acid.

[0014] In the above process, the organic titanium source is one or more of tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate and polyacrylate titanium.

[0015] In the above process, the aluminum source is one or more of α-phase or γ-phase nano-scale aluminum hydroxide, nano-diaspore-type hydroxide and lithium aluminate.

[0016] In the above process, the lithium source is one or more of lithium carbonate, lithium hydroxide, lithium acetate and lithium acetate.

[0017] In the above process, the carbon source is one or more of glucose, sucrose, graphite, carbon nanotubes and polyethylene glycol.

[0018] In the above process, the dispersion is carried out by high-speed stirring or homogenizing pump dispersion, and the dispersion frequency is 30 to 60 Hz, preferably 40 to 50 Hz.

[0019] In the above process, the drying is carried out by vacuum drying, flash evaporation or microwave drying, the drying temperature is 70 to 150° C., preferably 80 to 120° C., and the drying time is 30 to 90 minutes.

[0020] In the above process, the calcination temperature is preferably 600-750°C, the heating rate is 2-8 min / °C, and the calcination time is 2-8 h; the calcination temperature is preferably 650-700°C, the heating rate is preferably 3-5°C / min, and the calcination time is preferably 4-6 h.

[0021] The first object of the present invention is to provide a nano-carbon composite lithium titanium aluminum phosphate conductive functional material, which is prepared by the above-mentioned preparation process, and the average primary particle size of the material is less than 100 nanometers.

[0022] The carbon content of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material is 0.5-5%, and more preferably 1-3%.

[0023] The second object of the present invention is to provide an application of the above-mentioned nano-carbon composite lithium aluminum titanium phosphate conductive functional material in the modification of electrode materials, wherein the modification method is surface coating or mixing with electrode materials.

[0024] In the above application, when the electrode material is modified by coating, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material to the matrix material is 0.1-5%; when the electrode material is modified by blending, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material to the matrix material is 0.1-5%.

[0025] The third object of the present invention is to provide a method for preparing a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry, by homogenizing, ball milling or high-speed dispersing the above-mentioned nano-carbon composite lithium titanium aluminum phosphate conductive functional material with water and a dispersant to obtain a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry.

[0026] In the above preparation method, the solid content of the ultra-dispersible slurry is 5 to 35%, preferably 15 to 30%.

[0027] In the above preparation method, the time for the homogeneous dispersion, ball milling dispersion or high-speed dispersion is 1 to 4 hours, preferably 2 to 3 hours.

[0028] In the above preparation method, the dispersant is polyethylene glycol, polyvinyl alcohol, polyacrylamide, and the amount of the dispersant is 0.02-5%.

[0029] The fourth object of the present invention is to provide a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry, which is prepared by the above-mentioned preparation method.

[0030] The fifth object of the present invention is to provide an application of the above-mentioned nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry in electrode material modification, wherein the modification method is surface coating.

[0031] In the above application, when the electrode material is modified by coating, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry to the matrix material is 0.5-10%.

[0032] In the above application, when the electrode material is modified by coating, the heat treatment temperature is 150 to 800° C. and the treatment time is 30 to 300 min.

[0033] Due to the adoption of the above technical solution, the advantages of the present invention are:

[0034] ① The preparation process of the present invention adopts a step-by-step addition method of the synthetic components, so that the reaction is carried out selectively, which is beneficial to improving the uniformity of mixing, controlling the reaction rate, optimizing the reaction conditions, and increasing the utilization rate of raw materials. In particular, a more stable compound is selected for the aluminum source to avoid the generation of heterogeneous aluminum phosphate in the precursor preparation, which affects the purity and quality of the target product.

[0035] ② The composite carbon source of the present invention uses an interfacial electronic conductive layer formed by in-situ growth, which is different from the traditional dry or wet coating method on the substrate material, avoiding the surface damage and performance degradation of the substrate material that may be caused by subsequent treatment. The in-situ composite method improves the compatibility of the carbon composite layer with the substrate, simplifies the synthesis process, effectively controls the primary particle size and the dispersibility of the powder material, and controls the thickness, composition and structure of the carbon composite layer, thereby achieving fine regulation and modification of material properties.

[0036] ③ The nano-carbon composite lithium aluminum titanium phosphate conductive functional material synthesized by the present invention is used as a conductive functional material to modify the electrode material, and assists in strengthening the electronic conductivity of the electrode material. The usage is not limited to the traditional blending form. The powder or slurry of the functional material can be used as a micron powder positive electrode material, negative electrode material and diaphragm for surface coating. After a simple heat treatment, it can enhance the performance of the electrode material and play a positive role in improving the safety of the battery system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a SEM image of the nano-lithium aluminum titanium phosphate LATP material without carbon composite in Comparative Example 1;

[0038] Figure 2 This is a SEM image of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material in Comparative Example 2;

[0039] Figure 3 This is a SEM image of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material in Example 3;

[0040] Figure 4 XRD patterns of Comparative Example 1, Example 2, Example 3 and Standard Card 35-0735;

[0041] Figure 5 The electrochemical impedance spectroscopy and equivalent circuit fitting curves of Example 2 and Example 3;

[0042] Figure 6This is a diagram of the equivalent circuit model of the blocking electrode used to test the LATP-C ceramic sheet. DETAILED DESCRIPTION

[0043] In order to better understand the technical solutions of the embodiments of the present application, they are further described below in conjunction with some preferred embodiments of the present application.

[0044] In this specification, amounts, ratios and other numerical values ​​are sometimes presented herein in a range format. It should be understood that such a range format is used for convenience and brevity, and should be flexibly understood to include not only the values ​​explicitly specified as range limits, but also all individual values ​​or sub-ranges encompassed within the range, as if each value and sub-range were explicitly specified.

[0045] The present invention discloses a process for preparing a nano-carbon composite lithium titanium aluminum phosphate conductive functional material. The molecular formula of the material is Li 1+x Al x Ti 2-x (PO4)3-C y , x=0.25-0.45, y=0.2-1.5, and the preparation process comprises the following steps:

[0046] Step 1. dispersing a lithium source into an organic solvent to obtain a slurry A;

[0047] Step 2. Continue to disperse the aluminum source into the A slurry to obtain the B slurry;

[0048] Step 3. dispersing the organic titanium source into the B slurry to obtain the C slurry;

[0049] Step 4. dissolving the carbon source and the phosphorus source in water to obtain a D solution;

[0050] Step 5. Slowly add the D solution to the C slurry, stirring while adding, so that the organic titanium source is slowly hydrolyzed, and the carbon source and the phosphorus source in the D solution are evenly dispersed to obtain a nano-LATP-C conductive functional material precursor sol slurry;

[0051] Step 6. After the nano-LATP-C conductive functional material precursor sol slurry is dried by microwave or hot air to remove water and organic volatiles, it is calcined under the protection of an inert gas such as nitrogen or argon, and crushed to obtain the nano-LATP-C conductive functional material.

[0052] According to some embodiments of the present application, the organic solvent is one or more of anhydrous ethanol, isopropanol and acetic acid.

[0053] According to some embodiments of the present application, the phosphorus source is one or more of diammonium phosphate, dilithium phosphate and phosphoric acid.

[0054] According to some embodiments of the present application, the organic titanium source is one or more of tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate and polyacrylate titanium.

[0055] According to some embodiments of the present application, the aluminum source is one or more of α-phase or γ-phase nano-sized aluminum hydroxide, nano-diaspore-type hydroxide, and lithium aluminate.

[0056] According to some embodiments of the present application, the lithium source is one or more of lithium carbonate, lithium hydroxide, lithium acetate and lithium acetate.

[0057] According to some embodiments of the present application, the carbon source is one or more of glucose, sucrose, graphite, carbon nanotubes and polyethylene glycol.

[0058] According to some embodiments of the present application, the dispersion is carried out by high-speed stirring or homogenizing pump dispersion, and the dispersion frequency is 30 to 60 Hz, preferably 40 to 50 Hz.

[0059] According to some embodiments of the present application, the drying is performed by vacuum drying, flash evaporation or microwave drying, the drying temperature is 70 to 150° C., preferably 80 to 120° C., and the drying time is 30 to 90 min.

[0060] According to some embodiments of the present application, the calcination temperature is preferably 600-750°C, the heating rate is 2-8 min / °C, and the calcination time is 2-8 h; the calcination temperature is preferably 650-700°C, the heating rate is preferably 3-5°C / min, and the calcination time is preferably 4-6 h.

[0061] Some embodiments of the present application also provide a nano-carbon composite lithium titanium aluminum phosphate conductive functional material, which is prepared by the above-mentioned preparation process, and the average primary particle size of the material is less than 100 nanometers.

[0062] The carbon content in the nano-carbon composite lithium titanium aluminum phosphate conductive functional material is 0.5-5%, and more preferably 1-3%.

[0063] Some embodiments of the present application also provide a method for preparing a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry, which can obtain a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry by homogenizing, ball milling or high-speed dispersing the above-mentioned nano-carbon composite lithium titanium aluminum phosphate conductive functional material with water and a dispersant.

[0064] In the above preparation method, the solid content of the ultra-dispersible slurry is 5 to 35%, preferably 15 to 30%.

[0065] In the above preparation method, the time for the homogeneous dispersion, ball milling dispersion or high-speed dispersion is 1 to 4 hours, preferably 2 to 3 hours.

[0066] In the above preparation method, the dispersant is polyethylene glycol, polyvinyl alcohol, citric acid or polyacrylamide, and the amount of the dispersant is 0.02-5%.

[0067] Some embodiments of the present application also provide a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersion slurry, which is prepared by the above-mentioned preparation method.

[0068] Some embodiments of the present application also provide an application of the above-mentioned nano-carbon composite lithium titanium aluminum phosphate conductive functional material and the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry in electrode material modification, wherein the modification method is surface coating or mixing with electrode materials.

[0069] In the above application, when the electrode material is modified by coating, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material to the matrix material is 0.1-5%.

[0070] In the above application, when the electrode material is modified by coating, the heat treatment temperature is 150 to 800° C. and the treatment time is 30 to 300 min.

[0071] In the above application, when the electrode material is modified by mixing, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material to the matrix material is 0.1-5%.

[0072] The lithium ion conductivity test of the nano-carbon composite lithium aluminum titanium phosphate conductive functional material of the present application is obtained by the AC impedance method. Specifically, the nano-carbon composite lithium aluminum titanium phosphate conductive functional material is pressed into a sheet on a tablet press, and then prepared into a blocking electrode after high-temperature annealing. The electrode is connected to the electrochemical workstation for AC impedance testing, and the lithium ion conductivity of the material is obtained by equivalent circuit fitting calculation. Among them, the equivalent circuit model of the blocking electrode used to test the LATP-C ceramic sheet is shown in the figure below: Figure 6 shown.

[0073] The electronic conductivity test of the nano-carbon composite lithium aluminum titanium phosphate conductive functional material of the present application is characterized by testing the constant pressure powder resistivity method: specifically, 5g of nano LATP-C powder is weighed and the powder resistivity is read with a probe powder resistance meter under a pressure of 159MPa, and its electronic conductivity is judged according to the value.

[0074] The relative density test of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material of the present application is specifically to press the nano-carbon composite lithium titanium aluminum phosphate conductive functional material powder into a sheet on a tablet press, and then anneal it at a high temperature to obtain a ceramic sheet. The relative density can be obtained by calculating the ratio of the measured density and the theoretical density of lithium titanium aluminum phosphate 2.9g / .

[0075] The carbon content of the nano-carbon composite lithium aluminum titanium phosphate conductive functional material prepared by the present invention is tested by thermogravimetric analysis. Specifically, the nano-carbon composite lithium aluminum titanium phosphate conductive functional material powder is kept at a constant temperature of 850°C for 60 minutes in an oxygen atmosphere. The carbon content of the nano-carbon composite lithium aluminum titanium phosphate conductive functional material prepared by the present method can be determined by calculating the ratio of the mass change before and after calcination to the mass before calcination.

[0076] The primary particle size of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material powder of the present application is measured using a field scanning electron microscope scale, and the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry is ultrasonically dispersed and then measured using a Malvern 2000 laser particle size analyzer.

[0077] The following specific examples illustrate the nano-carbon composite lithium titanium aluminum phosphate conductive functional material and its preparation process and application proposed in this application. It should be emphasized that the present application is not limited to the examples shown. All related work in this field that is expanded through modification, replacement, improvement, reordering, etc. should be included in the protection scope of the present invention. The reagents or instruments not recorded in the text of this application are all contents that can be routinely confirmed by ordinary technicians in this field.

[0078] Comparative Example 1

[0079] As a comparative example, lithium acetate, nano-alumina, tetrabutyl titanate and diammonium phosphate were weighed according to the stoichiometric ratio of Li, Al, Ti and P of 1.3:0.3:1.7:3, and the liquid-to-solid ratio of the organic solvent was matched to 3-5 according to the mass of the synthetic product;

[0080] Lithium acetate, nano-alumina, and tetrabutyl titanate are synthesized according to the steps described in the above preparation process. The raw materials are dispersed step by step into an organic solvent isopropanol solution under high-speed dispersion conditions, and then an aqueous solution of ammonium dihydrogen phosphate is slowly added. After the tetrabutyl titanate is completely hydrolyzed, a precursor sol slurry of lithium aluminum titanium phosphate is obtained. After vacuum drying at 85°C / 80min, a lithium aluminum titanium phosphate precursor is obtained. After calcination and ball milling at 650°C / 5h in an air atmosphere in a muffle furnace, a nano lithium aluminum titanium phosphate LATP material without composite carbon is obtained, and its SEM image is as shown in the figure. Figure 1 shown.

[0081] Example 2

[0082] This embodiment is based on Comparative Example 1. While introducing a phosphorus source, 5% of a carbon source, glucose, is introduced and simultaneously added to a slurry containing lithium, aluminum, and titanium sources to obtain a nano-carbon composite LATP-C precursor sol slurry. After vacuum drying at 85°C / 80min, a lithium aluminum titanium phosphate precursor is obtained. After calcining and ball milling at 650°C / 5h in a muffle furnace under a nitrogen or argon atmosphere, a nano-carbon composite lithium aluminum titanium phosphate conductive functional material is obtained. The SEM image thereof is shown in FIG. Figure 2 shown.

[0083] Example 3

[0084] This example further verifies the synthesis of nano-carbon composite lithium aluminum titanium phosphate conductive functional materials according to different raw materials and different component ratios based on Example 2. The specific steps are: lithium hydroxide monohydrate, aluminum hydroxide, tetrabutyl titanate, phosphoric acid and sucrose are weighed according to the stoichiometric ratio of Li, Al, Ti, P and C of 1.4:0.4:1.6:3:0.2; the liquid-solid ratio of the organic solvent is matched to 3-5 according to the quality of the synthetic product;

[0085] The aqueous lithium hydroxide, aluminum hydroxide and tetrabutyl titanate are synthesized according to the steps described in the above preparation process, and the raw materials are dispersed step by step into an organic solvent anhydrous ethanol solution under high-speed dispersion conditions, and then an aqueous solution of phosphoric acid and a carbon source is slowly added, and the precursor sol slurry of nano-carbon composite lithium aluminum titanium phosphate is obtained after the tetrabutyl titanate is completely hydrolyzed. After vacuum drying at 85°C / 80min, a precursor of a nano-carbon composite lithium aluminum titanium phosphate conductive functional material is obtained. After calcining and ball milling at 650°C / 5h in a muffle furnace under a nitrogen or argon atmosphere, the nano-carbon composite lithium aluminum titanium phosphate conductive functional material has a SEM image as shown below. Figure 3 shown.

[0086] Example 4

[0087] In this embodiment, a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry is prepared on the basis of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material synthesized in Example 2. 0.5% of polyethylene glycol 6000 is added as a dispersant at a liquid-to-solid ratio of 1:3. A ball milling dispersion method is adopted for a dispersion time of 2 hours to obtain a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry with a solid content of 25%, which is stable and non-stratified.

[0088] Example 5

[0089] In this embodiment, a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersible slurry is prepared on the basis of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material synthesized in Example 3. At a liquid-to-solid ratio of 1:4, 0.05% low-viscosity polyvinyl alcohol is added as a dispersant. The material is dispersed using a high-speed disperser for 3 hours to obtain a nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersible slurry with a solid content of 20% that is stable and not stratified.

[0090] Table 1 is the main test data of the examples in this application

[0091]

[0092] It can be seen from Table 1 that the nano-carbon composite lithium titanium aluminum phosphate conductive functional material provided by the present invention has high ionic conductivity and electronic conductivity. The prepared nano-powder and ultra-dispersed slurry have nano-sized primary particles with a particle size of less than 100 nanometers. Figure 1 to Figure 3 It is not difficult to find that the primary particles are highly single-crystal, the grain boundaries between the particles are clear and the dispersion is good. The electrochemical impedance spectrum of the blocked electrode prepared from the synthetic materials of Example 2 and Example 3 shows a high ionic conductivity. Figure 5 As shown, after fitting with the equivalent circuit model Figure 6 The present invention adopts a nano-carbon composite preparation method, so that lithium aluminum titanium phosphate is not limited to the scope of being used alone as a solid electrolyte. The carbon composite nano-modification cleverly gives the electronically insulating lithium aluminum titanium phosphate a higher electronic conductivity, making it easy to achieve the modification of electrode materials to inhibit the increase of charge migration impedance during the cycle of electrode materials, passivate the surface activity of electrode materials, slow down the structural degradation of materials during the cycle, reduce the decomposition of transition metal elements catalyzing electrolytes at high SOC, and reduce the gas production of side reactions at the interface of battery materials, playing a role as a special functional material in enhancing the overall safety of lithium-ion batteries.

Claims

1. A preparation process of nano-carbon composite lithium aluminum titanium phosphate conductive functional material, Features: The molecular formula of this material is Li 1+x Al x Ti 2-x (PO4)3-C y , x=0.25-0.45, y=0.2-1.5, and the preparation process comprises the following steps: Step 1. dispersing a lithium source into an organic solvent to obtain a slurry A; Step 2. Continue to disperse the aluminum source into the A slurry to obtain the B slurry; Step 3. dispersing the organic titanium source into the B slurry to obtain the C slurry; Step 4. dissolving a carbon source and a phosphorus source in water to obtain a D solution; Step 5. Slowly add the D solution to the C slurry, stirring while adding, so that the organic titanium source is slowly hydrolyzed, and the carbon source and the phosphorus source in the D solution are evenly dispersed to obtain a nano-LATP-C conductive functional material precursor sol slurry; Step 6. After drying the nano-LATP-C conductive functional material precursor sol slurry, calcine it under the protection of an inert gas such as nitrogen or argon, and grind it to obtain the nano-LATP-C conductive functional material.

2. The preparation process of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material according to claim 1, characterized in that: The aluminum source is one or more of α-phase or γ-phase nano-sized aluminum hydroxide, nano-diassite-type hydroxide and lithium aluminate.

3. The preparation process of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material according to claim 1, characterized in that: The carbon source is one or more of glucose, sucrose, graphite, carbon nanotubes and polyethylene glycol.

4. The preparation process of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material according to claim 1, characterized in that: The calcination temperature is 600-750° C., the heating rate is 2-8 min / ° C., and the calcination time is 2-8 h.

5. A nano-carbon composite lithium titanium aluminum phosphate conductive functional material, characterized in that: The nano-carbon composite lithium titanium aluminum phosphate conductive functional material is prepared by the preparation process described in any one of claims 1 to 4, and the average size of the primary particles of the material is less than 100 nanometers.

6. The nano-carbon composite lithium titanium aluminum phosphate conductive functional material according to claim 5, characterized in that: Its carbon content is 0.5-5%.

7. An application of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material as claimed in claim 5 or 6 in electrode material modification, characterized in that: The modification method is surface coating or mixing with electrode materials.

8. The use of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material in electrode material modification according to claim 7, characterized in that: When the electrode material is modified by coating, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material to the matrix material is 0.1-5%; when the electrode material is modified by blending, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material to the matrix material is 0.1-5%.

9. A method for preparing a nano-carbon composite lithium aluminum titanium phosphate conductive functional material ultra-dispersed slurry, characterized in that: The nano-carbon composite lithium titanium aluminum phosphate conductive functional material according to claim 5 or 6 is homogenously dispersed, ball-milled or high-speed dispersed to obtain the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry.

10. The method for preparing the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersion slurry according to claim 9, characterized in that: The solid content of the ultra-dispersed slurry is 5-35%.

11. A nano-carbon composite lithium aluminum titanium phosphate conductive functional material ultra-dispersed slurry, characterized by: The slurry is prepared by the preparation method described in claim 9 or 10.

12. An application of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry as claimed in claim 11 in electrode material modification, characterized in that: The modification method is surface coating.

13. The use of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry in electrode material modification according to claim 12, characterized in that: When the electrode material is modified by coating, the weight percentage of the nano-carbon composite lithium titanium aluminum phosphate conductive functional material ultra-dispersed slurry to the matrix material is 0.5-10%.

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