Preparation and application of 3D printed KVPO4F / rGO microlattice aerogel

Abstract

The application discloses preparation and application of 3D printing KVPO4F / rGO microcrystal lattice aerogel, and synthesizes microspherical KVPO4F amorphous powder through a hydrothermal method, improves material crystallinity through annealing, composites the KVPO4F powder with graphene oxide, and finally synthesizes layered porous KVPO4F / rGO microcrystal lattice aerogel electrode through 3D printing technology based on ink writing technology (DIW). The 3D printed microcrystal lattice provides a layered porous structure, microchannels and macro / mesopores formed by interconnected conductive sheets, promotes ion / electron transmission kinetics, improves electron conductivity and K + diffusion kinetics, greatly improves the rate and cycle performance of the composite material, increases the specific surface area, reduces the local current density, and realizes high surface capacity of the printed thick electrode. The prepared KVPO4F / rGO composite material exhibits excellent electrochemical performance, including higher discharge specific capacity and excellent rate performance, and the material has good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of battery materials technology, and in particular relates to the preparation and application of a 3D printed KVPO4F / rGO microlattice aerogel. Background Technology

[0002] Cathode materials used for potassium storage mainly include layered metal oxides, Prussian blue analogues, organic materials, and polyanionic compounds. Among them, polyanionic compounds have a stable framework structure, which can mitigate the volume change of the material during the intercalation reaction. KVPO4F has attracted attention due to its high operating voltage and high theoretical capacity.

[0003] However, the KVPO4F cathode still suffers from low capacity, poor cycle performance, and low rate performance, mainly due to the instability of the electrode / electrolyte interface and poor conductivity. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a 3D printing technique based on ink writing technology to prepare three-dimensional layered porous KVPO4F / rGO aerogel, thereby creating a three-dimensional electrode structure with high loading capacity and high specific capacity, which can be applied to potassium-ion batteries to solve the problems mentioned in the background technology.

[0005] This invention provides the following technical solution: The preparation method of 3D printed KVPO4F / rGO microlattice aerogel includes the following steps: S1, NH4H2PO4, KF, V2O5, H2C2O4·2H2O are added to a mixed solution of water and ethylene glycol and stirred. The resulting mixed solution is transferred to an autoclave, placed in an oven and heated, and finally washed and dried to obtain KVPO4F amorphous powder. S2, the obtained KVPO4F amorphous powder is placed in a high-temperature tube furnace for annealing to obtain highly crystalline KVPO4F powder; S3, the obtained KVPO4F powder is mixed with an aqueous solution of graphene oxide and centrifuged to obtain 3D printing slurry; S4. The obtained 3D printing slurry is filled into the syringe, and the micro-nozzle is fixed on the DIW 3D printer. The micro-lattice three-dimensional network pattern is printed through the nozzle with an inner diameter of 150 μm to obtain the KVPO4F / rGO electrode.

[0006] Further, in step S1, the molar ratio of NH4H2PO4, KF, V2O5, and H2C2O4·2H2O is 2:3:1:0.2.

[0007] Further, in step S1, the volume ratio of water to ethylene glycol in the mixed solution is 1:4, and the stirring temperature is room temperature.

[0008] Further, in step S1, the hydrothermal reaction temperature of the mixed solution is 160-180 °C, and the reaction time is 5-7 h. The preferred reaction time is 6 h.

[0009] Further, in step S1, the washing is performed sequentially with deionized water and anhydrous ethanol, the deionized water is centrifuged three times, and the anhydrous ethanol is centrifuged once. The drying temperature is 55-65℃. Preferably, the drying temperature is 60℃.

[0010] Further, in step S2, the KVPO4F amorphous powder is annealed under an argon atmosphere at a temperature of 550-650 °C for 4-6 hours. The preferred annealing temperature is 600 °C, and the preferred annealing time is 5 hours.

[0011] Furthermore, in step S3, the mass ratio of the KVPO4F powder to graphene oxide is 1:1.

[0012] Further, in step S3, the centrifugation is performed at 20,000 rpm for 20-30 minutes. The centrifugation time is preferably 25 minutes.

[0013] Furthermore, in step S4, during the printing process, the pressure is set between 0.15 and 0.25 MPa, and the syringe movement speed is 4-6 mm / s. The preferred movement speed is 5 mm / s.

[0014] Furthermore, the process includes step S5, in which the 3D network structure printed in step S4 is freeze-dried at -40°C for 2 days using a freeze dryer to remove excess moisture while maintaining the porous structure.

[0015] Furthermore, the process includes step S6, in which the dried 3D network structure is annealed under an argon atmosphere to reduce graphene oxide. The annealing temperature is 600 °C and the annealing time is 2 h.

[0016] Furthermore, the method for applying 3D-printed KVPO4F / rGO microlattice aerogel is described, wherein the KVPO4F / rGO microlattice aerogel prepared by the method is applied to the positive electrode material of potassium-ion batteries.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention relates to the preparation and application of 3D-printed KVPO4F / rGO microlattice aerogel. The 3D-printed microlattice provides a layered porous structure, with microchannels and macro / mesopores formed by interconnected conductive sheets, which promotes ion / electron transport dynamics.

[0018] This invention relates to the preparation and application of 3D-printed KVPO4F / rGO microlattice aerogels. The KVPO4F / rGO composite material improves electronic conductivity and K... + Diffusion kinetics improved the rate and cycling performance of the composite material.

[0019] This invention relates to the preparation and application of 3D-printed KVPO4F / rGO microlattice aerogel. The combination of KVPO4F powder and rGO is beneficial to improving the conductivity of the material, maintaining the stability of the electrode / electrolyte interface, and reducing the loss of fluoride ions during cycling.

[0020] This invention relates to the preparation and application of 3D-printed KVPO4F / rGO microlattice aerogel, and the printed thick electrode will achieve high areal capacity.

[0021] The present invention relates to the preparation and application of 3D-printed KVPO4F / rGO microcrystalline aerogel, which increases the specific surface area and reduces the local current density.

[0022] This invention relates to the preparation and application of 3D-printed KVPO4F / rGO microcrystalline aerogel. The prepared KVPO4F / rGO composite material exhibits excellent electrochemical performance, including high discharge specific capacity and excellent rate performance, and this material has good application prospects. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a flowchart of the method of the present invention.

[0025] Figure 2 The image shows the X-ray diffraction pattern of the KVPO4F material prepared according to an embodiment of the present invention.

[0026] Figure 3 The X-ray photoelectron spectrum of the KVPO4F material prepared in an embodiment of the present invention.

[0027] Figure 4The image shows a scanning electron microscope (SEM) image of the KVPO4F / rGO material prepared in an embodiment of the present invention at 50x magnification.

[0028] Figure 5 Scanning electron microscope image of KVPO4F / rGO material prepared for an embodiment of the present invention at 1600x magnification.

[0029] Figure 6 The graph shows the cycle performance of the KVPO4F / rGO material prepared in this embodiment of the invention for use in a potassium-ion battery. Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. Example

[0032] Please see Figure 1-6 As shown, the preparation method of 3D printed KVPO4F / rGO microlattice aerogel includes the following steps: S1, NH4H2PO4, KF, V2O5, H2C2O4·2H2O are added to a mixed solution of water and ethylene glycol and stirred. The resulting mixed solution is transferred to an autoclave, placed in an oven and heated, and finally washed and dried to obtain KVPO4F amorphous powder. S2, the obtained KVPO4F amorphous powder is placed in a high-temperature tube furnace for annealing to obtain highly crystalline KVPO4F powder; S3, the obtained KVPO4F powder is mixed with an aqueous solution of graphene oxide and centrifuged to obtain 3D printing slurry; S4. The obtained 3D printing slurry is filled into the syringe, and the micro-nozzle is fixed on the DIW 3D printer. The micro-lattice three-dimensional network pattern is printed through the nozzle with an inner diameter of 150 μm to obtain the KVPO4F / rGO electrode.

[0033] In step S1, the molar ratio of NH4H2PO4, KF, V2O5, and H2C2O4·2H2O is 2:3:1:0.2.

[0034] In step S1, the volume ratio of water to ethylene glycol in the mixed solution is 1:4, and the stirring temperature is room temperature.

[0035] In step S1, the hydrothermal reaction temperature of the mixed solution is 160-180 °C, and the reaction time is 5-7 h. The preferred reaction time is 6 h.

[0036] In step S1, the washing process involves sequentially washing with deionized water and anhydrous ethanol. The deionized water is centrifuged three times, and the anhydrous ethanol is centrifuged once. The drying temperature is 55-65℃, preferably 60℃.

[0037] In step S2, the KVPO4F amorphous powder is annealed under an argon atmosphere at a temperature of 550-650℃ for 4-6 hours. The preferred annealing temperature is 600℃, and the preferred annealing time is 5 hours.

[0038] In step S3, the mass ratio of KVPO4F powder to graphene oxide is 1:1.

[0039] In step S3, the centrifugation is performed at 20,000 rpm for 20-30 minutes. The preferred centrifugation time is 25 minutes.

[0040] In step S4, during the printing process, the pressure is set between 0.15 and 0.25 MPa, and the syringe movement speed is 4-6 mm / s. The preferred movement speed is 5 mm / s.

[0041] KVPO4F powder was prepared by hydrothermal reaction. At room temperature, 0.46 g of NH4H2PO4, 0.348 g of KF, 0.367 g of V2O5, and 0.05 g of H2C2O4·2H2O were weighed and added to a mixed solution of 10 ml deionized water and 40 ml of ethylene glycol, and stirred vigorously for 2 h. The solution was then poured into a 50 ml Teflon-lined stainless steel autoclave and heated continuously at 170 °C for 6 h in an oven. The hydrothermally obtained sample was then washed three times with deionized water, followed by one wash with anhydrous ethanol, and dried at 60 °C for 6 h in an oven. Finally, the KVPO4F amorphous powder was annealed at 600 °C for 5 h in a high-temperature tube furnace under an argon atmosphere.

[0042] Preparation of KVPO4F / rGO ink: 0.2 g of KVPO4F powder was mixed with 40 ml of graphene oxide aqueous solution (5 mg / ml), centrifuged at 20000 rpm for 25 min, and the precipitate obtained by centrifugation was ground to obtain KVPO4F / rGO ink.

[0043] 3D printing of KVPO4F / rGO electrodes. 3D printing slurry was filled into a syringe (5 ml), and a micro-nozzle was fixed to a modified DIW 3D printer. A microlattice three-dimensional network pattern was printed on a glass substrate through a nozzle with an inner diameter of 150 μm. During printing, the pressure was set between 0.15 and 0.25 MPa, and the syringe movement speed was 5 mm / s. -1 .

[0044] The 3D mesh structure KVPO4F / rGO electrode obtained in this example has a large porosity, which is beneficial for the transport of electrons and ions. The combination of KVPO4F powder and rGO helps to improve the conductivity of the material, maintain the stability of the electrode / electrolyte interface, and reduce the loss of fluoride ions during cycling. In addition, the KVPO4F / rGO electrode has a high areal capacity.

[0045] 3D-printed microlattices provide a hierarchical porous structure, with microchannels and macro / mesopores formed by interconnected conductive sheets, promoting ion / electron transport dynamics; improving electronic conductivity and K0. + Diffusion kinetics significantly improve the rate and cycling performance of the composite material; increased specific surface area reduces local current density; and the printed thick electrode achieves high areal capacity. The prepared KVPO4F / rGO composite material exhibits excellent electrochemical performance, including high discharge specific capacity and excellent rate performance, and this material has promising application prospects.

[0046] Figure 2 This is the X-ray diffraction pattern of the KVPO4F material prepared in the embodiments of the present invention, which can be attributed to orthogonal KTiOPO4 (JCPDS card number 70-2073).

[0047] Figure 3 The image shows the X-ray photoelectron spectrum of the KVPO4F material prepared according to an embodiment of the present invention, which shows that the material contains K, V, P, O, F elements and a small amount of N element. Figure 4 This is a scanning electron microscope image of the KVPO4F / rGO material prepared in the embodiment of the present invention at 50x magnification, which shows that the 3D printed KVPO4F / rGO has a porous structure. Figure 5This is a scanning electron microscope image of the KVPO4F / rGO material prepared in the embodiment of the present invention at 1600x magnification, which shows that most of the KVPO4F particles in the KVPO4F / rGO composite material are encapsulated by rGO. Figure 6 This is a cycle performance diagram of the KVPO4F / rGO material prepared in Example 1 of this invention for potassium-ion batteries. The capacity of the KVPO4F / rGO composite material is improved, and the capacity retention rate is 92.04% after 100 cycles. Example

[0048] Based on Example 1, step S5 is also included, in which the 3D network structure printed in step S4 is freeze-dried at -40 ℃ for 2 days using a freeze dryer to remove excess moisture while maintaining the porous structure.

[0049] The process also includes step S6, in which the dried 3D network structure is annealed in an argon atmosphere to reduce graphene oxide. The annealing temperature is 600 °C and the annealing time is 2 h.

[0050] The 3D mesh structure obtained by 3D printing was freeze-dried for 48 hours to obtain a self-supporting 3D printed structure.

[0051] The KVPO4F / rGO electrode was reduced by annealing. The dried KVPO4F / rGO self-supporting electrode was placed in a high-temperature tube furnace and annealed at 600 °C for 2 h in an argon atmosphere, with a heating time of 2 °C / min. Example

[0052] Based on Example 1, the application method of 3D printed KVPO4F / rGO microlattice aerogel is described, and the KVPO4F / rGO microlattice aerogel prepared by the method is applied to the positive electrode material of potassium-ion battery.

[0053] 3D printing technology based on ink writing technology was used to prepare three-dimensional layered porous KVPO4F / rGO aerogel, which was used to prepare a three-dimensional electrode with high loading capacity and high specific capacity for application in potassium-ion batteries.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations; any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing 3D-printed KVPO4F / rGO microlattice aerogel, characterized in that, Includes the following steps: S1, NH4H2PO4, KF, V2O5, H2C2O4·2H2O are added to a mixed solution of water and ethylene glycol and stirred. The resulting mixed solution is transferred to an autoclave, placed in an oven and heated, and finally washed and dried to obtain KVPO4F amorphous powder. S2, the obtained KVPO4F amorphous powder is placed in a high-temperature tube furnace for annealing to obtain highly crystalline KVPO4F powder; S3, the obtained KVPO4F powder is mixed with an aqueous solution of graphene oxide and centrifuged to obtain 3D printing slurry; S4. The obtained 3D printing slurry is filled into the syringe, and the micro-nozzle is fixed on the DIW 3D printer. The micro-lattice three-dimensional network pattern is printed through the nozzle with an inner diameter of 150 μm to obtain the KVPO4F / rGO electrode.

2. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 1, characterized in that, In step S1, the molar ratio of NH4H2PO4, KF, V2O5, and H2C2O4·2H2O is 2:3:1:0.

2.

3. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 2, characterized in that, In step S1, the volume ratio of water to ethylene glycol in the mixed solution is 1:4, and the stirring temperature is room temperature.

4. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 3, characterized in that, In step S1, the hydrothermal reaction temperature of the mixed solution is 160-180 ℃, and the reaction time is 5-7 h.

5. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 4, characterized in that, In step S1, the washing is performed successively with deionized water and anhydrous ethanol. The deionized water is centrifuged three times, and the anhydrous ethanol is centrifuged once. The drying temperature is 55-65℃.

6. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 1, characterized in that, In step S2, the KVPO4F amorphous powder is annealed under an argon atmosphere at a temperature of 550-650 ℃ for 4-6 h.

7. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 1, characterized in that, In step S3, the mass ratio of KVPO4F powder to graphene oxide is 1:

1.

8. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 7, characterized in that, In step S3, the centrifugation is performed at 20,000 rpm for 20-30 minutes.

9. The method for preparing 3D-printed KVPO4F / rGO microlattice aerogel according to claim 1, characterized in that, In step S4, during the printing process, the pressure is set between 0.15 and 0.25 MPa, and the syringe movement speed is 4-6 mm / s.

10. The KVPO4F / rGO microcrystalline aerogel prepared by the method of any one of claims 1-9 is used as a cathode material in potassium-ion batteries.

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