Application of binary vanadium-based phosphate as anode protection layer material

Abstract

The invention discloses an application of binary vanadium-based phosphate as an anode protective layer material in an aqueous zinc ion battery, the binary vanadium-based phosphate is MxVy (PO4) 3, and M is Zn, Li, Na or Mg, 0 lt; xlt; 1, 1lt; yt; Yt; 2; the binary vanadium-based phosphate MxVy (PO4) 3 is in a three-dimensional honeycomb shape; the electrolyte in the aqueous zinc ion battery is ZnSO4; the preparation method of the MxVy (PO4) 3 comprises the following steps: mixing a complexing agent, phosphate, vanadium salt and one or more of zinc salt, lithium salt, sodium salt or magnesium salt in a solvent, stirring at room temperature, and synthesizing M, V-PO4 < 3-> by a sol-gel method; the vanadium salt is ammonium metavanadate; and calcining the prepared M, V-PO4 < 3-> at a high temperature in a nitrogen atmosphere to obtain MxVy (PO4) 3. In the application, the binary vanadium-based phosphate is used as an anode protection layer material, so that direct contact between free water and a Zn cathode can be avoided, a Zn metal anode electrode-electrolyte interface is further stabilized, and the problems of dendritic crystal growth, hydrogen evolution reaction, corrosion, passivation and the like in an aqueous zinc ion battery can be solved, so that the reversibility and the stability of the zinc cathode are improved, and the service life of the zinc cathode is prolonged. The cycle life of the battery is prolonged.

Description

Technical Field

[0001] The present invention belongs to the field of application of aqueous zinc ion battery materials, and particularly relates to the application of a binary vanadium-based phosphate as an anode protective layer material. Background Art

[0002] The depletion of fossil energy and environmental deterioration are two major severe challenges currently faced by mankind. Developing advanced electrochemical energy storage devices to safely collect and store renewable clean energy is considered the key to solving the above problems.

[0003] Since the advent of aqueous batteries in 1994, due to their advantages such as safe operation, low manufacturing cost, environmental friendliness, and fast charging, they have shown broad application prospects in advanced large-scale grid energy storage systems and are considered potential competitors to LiBs. Among them, metallic zinc (Zn) has become an ideal negative electrode material for aqueous batteries due to its high theoretical capacity (820 mA·h g -1 ), suitable redox potential (-0.76 V vs. SHE), good aqueous solution compatibility, and abundant resources. However, during the actual application process, some reactions in the aqueous electrolyte solution will affect the zinc deposition process, resulting in a decrease in the Coulombic efficiency of zinc deposition / stripping and incomplete dissolution of zinc. Therefore, zinc ions will gradually deposit unevenly on the surface of the zinc metal negative electrode, forming needle-like and flaky zinc dendrites. As the zinc dendrites continue to form and grow, their mechanical rigidity and uneven structure will cause them to fall off from the surface of the zinc negative electrode, forming "dead zinc", resulting in a reduction in the active substances of the battery and capacity decline. Zinc dendrites may also pierce the separator, causing internal short circuit of the battery. In addition, the coexistence of zinc and water is thermodynamically unstable. Since the hydrogen evolution potential is higher than the standard electrode potential of Zn 2+ / Zn, the hydrogen evolution reaction often occurs during the electrochemical cycling process. Along with the hydrogen evolution reaction, side reactions such as corrosion pits and passivation will also appear on the surface of the zinc negative electrode, resulting in a decrease in the Coulombic efficiency of the battery, battery swelling, and a decrease in cycle stability. And the above-mentioned adverse side reactions on the surface of the zinc negative electrode do not occur independently and will affect and promote each other.

[0004] At present, many strategies are dedicated to improving the performance of ZIBs by optimizing zinc electrodes, including modification of the surface protective layer of zinc metal anodes, electrode structure design, electrolyte optimization, and separator modification, etc. Among them, electrode structure design usually requires pre-depositing zinc metal through electrochemical deposition, which increases the complexity of the preparation process and makes it difficult to achieve large-scale expansion in industrial applications. The strategies of using electrolyte additives and separator modification cannot effectively isolate the zinc anode and the electrolyte, and have limited inhibitory effects on side reactions. In addition, high-concentration electrolytes and non-liquid electrolytes often result in high viscosity and low ionic conductivity of the electrolyte, compromising the advantages of ZIBs. In contrast, constructing an interfacial protection coating on the zinc metal anode has the advantages of a wide selection range, simple preparation, easy control, and high practical value. For example, the methods adopted in the existing technology are as follows: Zhu et al. used NaTi 2 (PO4) 3 three-dimensional porous nanoparticles as a solid-state electrolyte protection layer to induce uniform deposition of zinc ions and inhibit interfacial side reactions, which resulted in a cycle life of 250 h (1 mA·cm -2 , 1mAh·cm -2 ) (Liu M, Cai J, Ao H, et al. NaTi 2 (PO4) 3 Solid‐State Electrolyte Protection Layer on ZnMetal Anode for Superior Long‐Life Aqueous Zinc-Ion Batteries[J].AdvancedFunctional Materials, 2020.); Dai and He et al. used Na 3 V 2 (PO 4 ) 3 as a zinc anode protection layer, which can provide a large number of stable channels for Zn 2+ transport, thus enhancing the Zn 2+ deposition kinetics and regulating the Zn 2 + transport process through the ion confinement effect, which resulted in a cycle life of 500 h (0.5 mA·cm -2 , 0.25 mAh·cm -2)(Guo N, Peng Z, Huo W, et al. Stabilizing Zn Metal Anode Through Regulation of Zn Ion Transfer and Interfacial Behavior with a Fast Ion Conductor Protective Layer[J]. Small, 2023, 19(47).). However, there is still much room for improvement in the above surface engineering for the coating materials in stabilizing the Zn metal anode electrode-electrolyte interface, which will restrict its further application.

[0005] Therefore, how to optimize the zinc electrode and further improve the performance of ZIBs by constructing an anode protective layer material that can not only highlight the advantages of the three-dimensional porous structure but also further stabilize the Zn metal anode electrode-electrolyte interface is a research hotspot in this field. Summary of the Invention

[0006] The purpose of the present invention is to provide an application of a binary vanadium-based phosphate as an anode protective layer material; as an anode protective layer material, the binary vanadium-based phosphate can avoid the direct contact between free water and the Zn negative electrode, further stabilize the Zn metal anode electrode-electrolyte interface, and can also better solve problems such as dendrite growth, hydrogen evolution reaction, corrosion, and passivation existing in aqueous zinc-ion batteries, thereby improving the reversibility and stability of the zinc negative electrode and prolonging the cycle life of the battery.

[0007] To achieve the above invention purpose, the present invention provides the following technical solutions: An application of a binary vanadium-based phosphate as an anode protective layer material in an aqueous zinc-ion battery, wherein the binary vanadium-based phosphate is M x V y (PO 4 ) 3 , where M is Zn, Li, Na, or Mg, 0 < x < 1, and 1 < y < 2.

[0008] In the present invention, M x V y (PO 4 ) 3 can be Zn x V y (PO 4 ) 3 , Li x V y (PO 4 ) 3 , Na x V y (PO 4 )3 or Mg x V y (PO 4 ) 3 。

[0009] When the binary vanadium-based phosphate provided by the present invention is used as an anode protective layer material and as a negative electrode material for an aqueous zinc-ion battery, it can not only effectively inhibit the generation of hydrogen evolution, corrosion and by-products, but also regulate the electric field distribution, promote the uniform and rapid transmission of zinc ions, improve the stability of the Zn metal anode electrode-electrolyte interface, and thus further improve the battery performance.

[0010] Preferably, in the binary vanadium-based phosphate M x V y (PO 4 ) 3 : 0.2 ≤ x ≤ 0.8, 1.2 ≤ y ≤ 1.8. By controlling the ratio of metals M and V, the present invention can effectively regulate the electric field distribution, promote the uniform and rapid transmission of zinc ions, and improve the cycle life of the battery (the longest cycle life ≥ 587 h).

[0011] Preferably, in the binary vanadium-based phosphate M x V y (PO 4 ) 3 : 0.5 ≤ x ≤ 0.8, 1.5 ≤ y ≤ 1.2. By further optimizing the ratio of metals M and V, the present invention improves the cycle life of the battery (the longest cycle life ≥ 621 h).

[0012] Preferably, M in the binary vanadium-based phosphate M x V y (PO 4 ) 3 is Zn. When 0.2 ≤ x ≤ 0.8, 1.2 ≤ y ≤ 1.8, the cycle life of the battery ≥ 608 h; when 0.5 ≤ x ≤ 0.8, 1.5 ≤ y ≤ 1.2, the cycle life of the battery ≥ 1095 h.

[0013] In the present invention, the binary vanadium-based phosphate M x V y (PO 4 ) 3 is three-dimensional honeycomb-shaped.

[0014] The binary vanadium-based phosphate M x V y (PO 4 ) 3 is mixed with PVDF and spin-coated on a zinc foil as the negative electrode of an aqueous zinc-ion battery.

[0015] Furthermore, the prepared Zn x V y (PO 4 ) 3 , Li x V y (PO 4 ) 3 、Na x V y (PO 4 ) 3 or Mg x V y (PO 4 ) 3 It was mixed with PVDF in a ratio of 9:1, and evenly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 ° C for 12 h to obtain Zn x V y (PO 4 ) 3 , Li x V y (PO 4 ) 3 、Na x V y (PO 4 ) 3 and Mg x V y (PO 4 ) 3 electrode.

[0016] The electrolyte in the aqueous zinc ion battery is ZnSO 4 , the positive electrode is sodium vanadate coated carbon paper.

[0017] The present invention also provides a method for preparing the above binary vanadium-based phosphate, the preparation method comprising: (1) Mix the complexing agent, phosphate and vanadium salt, and one or more of zinc salt, lithium salt, sodium salt or magnesium salt in a solvent, stir at room temperature and synthesize M,V-PO by a sol-gel method. 4 3- , M is Zn, Li, Na, or Mg; (2) Prepared M,V-PO 4 3- Calcination under high temperature and nitrogen atmosphere to obtain a three-dimensional honeycomb M x V y (PO 4 ) 3 , where 0 <x<1,1<y<2。

[0018] The preparation principle of the present invention lies in: introducing metal atoms into the vanadium-based phosphate structural framework and embedding them into the vanadium-based phosphate structural framework by means of high-temperature calcination, and successfully forming M in the vanadium-based phosphate structural framework. x V y (PO 4 ) 3 Three-dimensional honeycomb materials, thereby constructing a three-dimensional interconnected porous structure. The synergistic effect of the metal elements M and V in the binary vanadium-based phosphate can provide continuous ion / electron transfer, which is beneficial to regulating the electric field distribution, homogenizing the zinc ion flow, realizing the rapid transmission of zinc ions, improving the stability of the Zn metal anode electrode-electrolyte interface, and then improving the cycle life of the battery.

[0019] In step (1), the solvent is deionized water.

[0020] In step (1), 2-20 mmol of complexing agent, 1-10 mmol of vanadium salt, 1-14 mmol of phosphate, and one of 1-18 mmol of zinc salt, 1-18 mmol of lithium salt, 1-18 mmol of sodium salt or 1-18 mmol of magnesium salt are added to the solvent. The molar mass ratio of the vanadium salt to the zinc salt, lithium salt, sodium salt or magnesium salt is 1:1-4.

[0021] Preferably, in step (1), the complexing agent is selected from anhydrous citric acid, the phosphate is selected from ammonium dihydrogen phosphate, the vanadium salt is selected from ammonium metavanadate, the zinc salt is selected from zinc nitrate hexahydrate, the lithium salt is selected from lithium nitrate, the sodium salt is selected from sodium nitrate, and the magnesium salt is selected from magnesium nitrate hexahydrate.

[0022] Preferably, step (1) is specifically: (1-1) Add 2-20 mmol of anhydrous citric acid to 20-200 mL of deionized water and stir at a speed of 400-800 r / min for 15-30 min at room temperature to obtain a mixed solution A for standby; (1-2) Put 1-10 mmol of ammonium metavanadate into the mixed solution A and stir at a speed of 400-800 r / min for 15-30 min at room temperature to obtain a mixed solution B for standby; (1-3) Put 1-14 mmol of ammonium dihydrogen phosphate and 1-18 mmol of zinc nitrate hexahydrate / 1-18 mmol of lithium nitrate / 1-18 mmol of sodium nitrate / 1-18 mmol of magnesium nitrate hexahydrate into the mixed solution B, continue to stir for 5-10 h, evaporate the solvent to obtain a blue gel-like substance, and put the prepared product into a vacuum oven at 75-85 °C for drying for 12-24 h to obtain the final M, V-PO 4 3-Powder. Appropriate molar mass ratio and reaction time will make the formation of M,V-PO 4 3- more uniform.

[0023] Preferably, 1-10 mmol of ammonium metavanadate and 1-18 mmol of zinc nitrate hexahydrate or 1-18 mmol of lithium nitrate or 1-18 mmol of sodium nitrate or 1-18 mmol of magnesium nitrate hexahydrate are added, and the molar mass ratio of ammonium metavanadate to zinc nitrate hexahydrate or lithium nitrate or sodium nitrate or magnesium nitrate hexahydrate is 1:1-4. By further regulating the types and proportions of metals in the three-dimensional honeycomb binary vanadium-based phosphate material, the present invention can further uniformly construct a three-dimensional interconnected porous structure, so that the finally prepared three-dimensional honeycomb binary vanadium-based phosphate anode protective layer material can effectively regulate the electric field distribution when applied in an aqueous zinc-ion battery, promote the uniform and rapid transmission of zinc ions, and improve the cycle life of the battery.

[0024] In step (2), the M,V-PO prepared in step (1) 4 3- is calcined at 300-900 °C in a nitrogen atmosphere for 2-15 h, and the heating rate is 2-7 °C·min -1 . Appropriate calcination temperature, calcination time and heating rate will make M x V y (PO 4 ) 3 the three-dimensional honeycomb material have better structure and performance, which is beneficial to improving the M x V y (PO 4 ) 3 three-dimensional honeycomb material effectively regulate the electric field distribution when applied in an aqueous zinc-ion battery, promote the uniform and rapid transmission of zinc ions, and improve the cycle life of the battery.

[0025] Compared with the prior art, the present invention has the following beneficial effects: 1. Aiming at the problems of dendrites, hydrogen evolution and corrosion of the zinc negative electrode during the battery cycle of the current aqueous zinc-ion battery, the present invention proposes to use the M x V y (PO 4 ) 3 three-dimensional honeycomb material as a coating to prepare an electrode protection coating. An appropriate ratio of metal M to V can homogenize the electric field distribution, inhibit dendrite growth, accelerate the transport kinetics of zinc ions, and the Zn 2+ transference number can reach 0.76, effectively improving the electrochemical performance of the zinc negative electrode; 2. The M x V y (PO 4) 3 As a coating, the three-dimensional honeycomb material can effectively reduce the direct contact between the zinc anode and the electrolyte, to a certain extent, avoid the generation of hydrogen evolution, corrosion and by-products, and thus improve the cycle stability of the aqueous zinc-ion battery; 3. The preparation method of the binary vanadium-based phosphate provided by the present invention has the advantages of simple preparation process, environmental friendliness, high repeatability, and low cost of raw materials used. Description of the Drawings

[0026] Figure 1 is a morphology diagram of the Zn 0.5 V 1.5 (PO 4 ) 3 material prepared in Example 1 observed by the S-4800 field emission scanning electron microscope (FE-SEM) of Hitachi, Japan; Figure 2 is a distribution diagram of the elements of the Zn 0.5 V 1.5 (PO 4 ) 3 material prepared in Example 1 observed by the S-4800 field emission scanning electron microscope (FE-SEM) of Hitachi, Japan; Figure 3 is the refined XRD pattern of Zn 0.5 V 1.5 (PO 4 ) 3 in Example 1 measured by the D8 X-ray diffractometer of Bruker, USA, where: the abscissa X is the diffraction angle (2θ), and the ordinate Y is the relative diffraction intensity; Figure 4 is the X-ray photoelectron spectrum (XPS) of Zn 0.5 V 1.5 (PO 4 ) 3 in Example 1 measured by the X-ray photoelectron spectrometer of model ESCALAB MKΙΙ, where: the abscissa X is the binding energy (eV), and the ordinate Y is the relative intensity (a.u.); Figure 5 is a distribution diagram of the cross-sectional elements of the Zn 0.5 V 1.5 (PO 4 ) 3 material prepared in Example 1 spin-coated on the surface of the zinc foil; Figure 6 is the Zn 0.5 V 1.5 (PO4 ) 3 The time - voltage graph of a symmetric aqueous zinc - ion battery using a button battery assembled with the material at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 ; Figure 7 This is the Zn 0.2 V 1.8 (PO 4 ) 3 button battery assembled with the material tested in Example 2 of the CT3001A electrochemical workstation of Wuhan Blue Electric Co., Ltd. at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 ; Figure 8 This is the Zn 0.8 V 1.2 (PO 4 ) 3 button battery assembled with the material tested in Example 3 of the CT3001A electrochemical workstation of Wuhan Blue Electric Co., Ltd. at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 ; Figure 9 This is the Mg 0.5 V 1.5 (PO 4 ) 3 button battery assembled with the material tested in Example 4 of the CT3001A electrochemical workstation of Wuhan Blue Electric Co., Ltd. at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 ; Figure 10 This is the Na 0.5 V 1.5 (PO 4 ) 3 button battery assembled with the material tested in Example 7 of the CT3001A electrochemical workstation of Wuhan Blue Electric Co., Ltd. at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 ; Figure 11 This is the Li 0.5 V 1.5 (PO 4 ) 3The button battery assembled with the material, at a current density of 1 mA·cm -2 , and an areal capacity of 1 mAh·cm -2 , the time-voltage graph of the aqueous zinc-ion battery symmetric cell; Figure 12 is the V 2 (PO 4 ) 3 The button battery assembled with the material, at a current density of 1 mA·cm -2 , and an areal capacity of 1 mAh·cm -2 , the time-voltage graph of the aqueous zinc-ion battery symmetric cell; Figure 13 is the Zn 3 (PO 4 ) 2 The button battery assembled with the material, at a current density of 1 mA·cm -2 , and an areal capacity of 1 mAh·cm -2 , the time-voltage graph of the aqueous zinc-ion battery symmetric cell; Figure 14 is the Zn 1.2 V 0.8 (PO 4 ) 3 The button battery assembled with the material, at a current density of 1 mA·cm -2 , and an areal capacity of 1 mAh·cm -2 , the time-voltage graph of the aqueous zinc-ion battery symmetric cell; Figure 15 is the button battery assembled with the unmodified zinc foil directly used as the negative electrode tested by the CT3001A electrochemical workstation of Wuhan Blue Electric Co., Ltd., at a current density of 1 mA·cm -2 , and an areal capacity of 1 mAh·cm -2 , the time-voltage graph of the aqueous zinc-ion battery symmetric cell. Detailed implementation mode

[0027] The above content of the present invention will be further described in detail below through embodiments, but it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments. Any technology implemented based on the above content of the present invention belongs to the scope of the present invention.

[0028] Embodiment 1 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 8 mmol of ammonium metavanadate was put into the mixed solution A and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution B; then 12 mmol of ammonium dihydrogen phosphate and 16 mmol of zinc nitrate hexahydrate were put into the mixed solution B, stirred at 50 °C for 3 h first, and then stirred at 88 °C for 3.5 h, and the solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C and dried for 12 h to obtain the final Zn,V-PO 4 3- powder. Then the prepared Zn,V-PO 4 3- was calcined at 400 °C for 4 h first and then at 750 °C for 8 h under a nitrogen atmosphere, and the heating rate was 5 °C·min -1 to obtain Zn 0.5 V 1.5 (PO 4 ) 3 three-dimensional honeycomb material. Finally, the prepared Zn 0.5 V 1.5 (PO 4 ) 3 was mixed with PVDF in a ratio of 9:1, and it was evenly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain the Zn 0.5 V 1.5 (PO 4 ) 3 electrode.

[0029] The SEM of the obtained product is shown in Figure 1 , and it can be observed that Zn 0.5 V 1.5 (PO 4 ) 3 presents a three-dimensional honeycomb structure, and it can be observed from Figure 2 that the elements Zn, V, P, and O contained are evenly distributed; according to Figure 3 the XRD and its refined pattern (PDF#01-076-0604), the physical degree of conformity (profile residual factor, R p ) is equal to 4.04%, and the mathematical degree of conformity (weighted profile residual factor, R wp ) is equal to 2.95%, both of which are far less than the maximum allowable fitting error (15.00%) of XRD refinement, indicating the successful preparation of Zn 0.5 V 1.5 (PO 4 ) 3 ; according to Figure 4XPS can further prove this, and as Figure 5 shown, the thickness of the prepared zinc anode coating material is 33 um, and the elements Zn, V, P, and O contained are evenly distributed. The Zn 0.5 V 1.5 (PO 4 ) 3 electrode has the following electrochemical performance: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the assembled symmetric cell can stably cycle for 3457 hours; the Zn 2+ transference number is as high as 0.76.

[0030] Example 2 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at a rotation speed of 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 4 mmol of ammonium metavanadate was put into the mixed solution A and stirred at a rotation speed of 500 r / min for 20 min at room temperature to obtain a mixed solution B; then 12 mmol of ammonium dihydrogen phosphate and 16 mmol of zinc nitrate hexahydrate were put into the mixed solution B, stirred at 50 °C for 3 h first, and then stirred at 88 °C for 3.5 h, and the solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C and dried for 12 h to obtain the final Zn,V-PO 4 3- powder. Then the prepared Zn,V-PO 4 3- was calcined at 400 °C for 4 h first and then at 750 °C for 8 h in a nitrogen atmosphere, and the heating rate was 5 °C·min -1 to obtain Zn 0.2 V 1.8 (PO 4 ) 3 three-dimensional honeycomb material. Finally, the prepared Zn 0.2 V 1.8 (PO 4 ) 3 was mixed with PVDF in a ratio of 9:1, and it was evenly spin-coated on a zinc foil with a thickness of 100 um and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain the Zn 0.2 V 1.8 (PO 4 ) 3 electrode.

[0031] The Zn 0.2 V 1.8 (PO 4 ) 3The electrochemical performance of the electrode is as follows: at a current density of 1 mA·cm -2 and areal capacity of 1 mAh·cm -2 the symmetric cell assembled therefrom can stably cycle for 608 hours.

[0032] Example 3 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 8 mmol of ammonium metavanadate was added to the mixed solution A and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution B; then 12 mmol of ammonium dihydrogen phosphate and 12 mmol of zinc nitrate hexahydrate were added to the mixed solution B, stirred at 50 °C for 3 h, and then stirred at 88 °C for 3.5 h. The solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C and dried for 12 h to obtain the final Zn,V-PO 4 3- powder. Then the prepared Zn,V-PO 4 3- was calcined at 400 °C for 4 h and then at 750 °C for 8 h in a nitrogen atmosphere with a heating rate of 5 °C·min -1 to obtain Zn 0.8 V 1.2 (PO 4 ) 3 three-dimensional honeycomb material. Finally, the prepared Zn 0.8 V 1.2 (PO 4 ) 3 was mixed with PVDF in a ratio of 9:1, and the mixture was uniformly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain the Zn 0.8 V 1.2 (PO 4 ) 3 electrode.

[0033] The electrochemical performance of the Zn 0.8 V 1.2 (PO 4 ) 3 electrode prepared in this example is as follows: at a current density of 1 mA·cm -2 and areal capacity of 1 mAh·cm -2 the symmetric cell assembled therefrom can stably cycle for 1095 hours.

[0034] Example 4 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 8 mmol of ammonium metavanadate was added to the mixed solution A and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution B; then 12 mmol of ammonium dihydrogen phosphate and 16 mmol of magnesium nitrate hexahydrate were added to the mixed solution B, stirred at 50 °C for 3 h, and then stirred at 88 °C for 3.5 h. The solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C and dried for 12 h to obtain the final Mg,V-PO 4 3- powder. Then the prepared Mg,V-PO 4 3- was calcined at 400 °C for 4 h and then at 750 °C for 8 h in a nitrogen atmosphere, and the heating rate was 5 °C·min -1 to obtain Mg 0.5 V 1.5 (PO 4 ) 3 three-dimensional honeycomb material. Finally, the prepared Mg 0.5 V 1.5 (PO 4 ) 3 was mixed with PVDF in a ratio of 9:1, and evenly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain the Mg 0.5 V 1.5 (PO 4 ) 3 electrode.

[0035] The electrochemical performance of the Mg 0.5 V 1.5 (PO 4 ) 3 electrode prepared in this example is as follows: at a current density of 1 mA·cm -2 and a surface capacity of 1 mAh·cm -2 , the assembled symmetric battery can stably cycle for 833 hours.

[0036] Example 5 The difference from Example 4 is that the molar amount of ammonium metavanadate is 4 mmol, and the Mg 0.2 V 1.8 (PO 4 ) 3 electrode is obtained.

[0037] The Mg 0.2 V 1.8 (PO 4 )3 The electrochemical performance of the electrode is as follows: at a current density of 1 mA·cm -2 and areal capacity of 1 mAh·cm -2 the symmetric cell assembled therefrom can stably cycle for 600 hours.

[0038] Example 6 The difference from Example 4 is that the number of moles of magnesium nitrate hexahydrate is 12 mmol, obtaining Mg 0.8 V 1.2 (PO 4 ) 3 electrode.

[0039] The Mg 0.8 V 1.2 (PO 4 ) 3 electrode prepared in this example has the following electrochemical performance: at a current density of 1 mA·cm -2 and areal capacity of 1 mAh·cm -2 the symmetric cell assembled therefrom can stably cycle for 782 hours.

[0040] Example 7 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at a rotation speed of 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 8 mmol of ammonium metavanadate was added to the mixed solution A and stirred at a rotation speed of 500 r / min for 20 min at room temperature to obtain a mixed solution B; then 12 mmol of ammonium dihydrogen phosphate and 16 mmol of sodium nitrate were added to the mixed solution B, stirred at 50 °C for 3 h first, and then stirred at 88 °C for 3.5 h, and the solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C and dried for 12 h to obtain the final Na,V-PO 4 3- powder. Then the prepared Na,V-PO 4 3- was calcined at 400 °C for 4 h first and then at 750 °C for 8 h in a nitrogen atmosphere, and the heating rate was 5 °C·min -1 to obtain Na 0.5 V 1.5 (PO 4 ) 3 three-dimensional honeycomb material. Finally, the prepared Na 0.5 V 1.5 (PO 4 ) 3 was mixed with PVDF in a ratio of 9:1, uniformly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain Na 0.5V 1.5 (PO 4 ) 3 Electrode.

[0041] The Na 0.5 V 1.5 (PO 4 ) 3 electrode prepared in this example has the following electrochemical performance: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the symmetric cell assembled with it can stably cycle for 750 hours.

[0042] Example 8 The difference from Example 7 is that the number of moles of ammonium metavanadate is 4 mmol, and Na 0.2 V 1.8 (PO 4 ) 3 electrode is obtained.

[0043] The Na 0.2 V 1.8 (PO 4 ) 3 electrode prepared in this example has the following electrochemical performance: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the symmetric cell assembled with it can stably cycle for 592 hours.

[0044] Example 9 The difference from Example 7 is that the number of moles of sodium nitrate is 12 mmol, and Na 0.8 V 1.2 (PO 4 ) 3 electrode is obtained.

[0045] The Na 0.8 V 1.2 (PO 4 ) 3 electrode prepared in this example has the following electrochemical performance: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the symmetric cell assembled with it can stably cycle for 660 hours.

[0046] Example 10 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 8 mmol of ammonium metavanadate was added to the mixed solution A and stirred at a speed of 500 r / min for 20 min at room temperature to obtain a mixed solution B; then 12 mmol of ammonium dihydrogen phosphate and 16 mmol of lithium nitrate were added to the mixed solution B, stirred at 50 °C for 3 h first, and then stirred at 88 °C for 3.5 h, and the solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C and dried for 12 h to obtain the final Li,V-PO 4 3- powder. Then the prepared Li,V-PO 4 3- was calcined at 400 °C for 4 h first and then at 750 °C for 8 h in a nitrogen atmosphere, and the heating rate was 5 °C·min -1 to obtain Li 0.5 V 1.5 (PO 4 ) 3 three-dimensional honeycomb material. Finally, the prepared Li 0.5 V 1.5 (PO 4 ) 3 was mixed with PVDF in a ratio of 9:1, and it was evenly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain Li 0.5 V 1.5 (PO 4 ) 3 electrode.

[0047] The electrochemical performance of the Li 0.5 V 1.5 (PO 4 ) 3 electrode prepared in this example is as follows: at a current density of 1 mA·cm -2 and a surface capacity of 1 mAh·cm -2 , the symmetric battery assembled with it can stably cycle for 728 hours.

[0048] Example 11 The difference from Example 10 is that the number of moles of ammonium metavanadate is 4 mmol, and Li 0.2 V 1.8 (PO 4 ) 3 electrode is obtained.

[0049] The Li 0.2 V 1.8 (PO 4 )3 The electrochemical performance of the electrode is as follows: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the symmetric cell assembled therefrom can stably cycle for 587 hours.

[0050] Example 12 It is different from Example 10 in that the number of moles of lithium nitrate is 12 mmol, and Li 0.8 V 1.2 (PO 4 ) 3 electrode is obtained.

[0051] The Li 0.8 V 1.2 (PO 4 ) 3 electrode prepared in this example has the following electrochemical performance: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the symmetric cell assembled therefrom can stably cycle for 621 hours.

[0052] Comparative Example 1 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 8 mmol of ammonium metavanadate was added to the mixed solution A and stirred at 50 r / min for 20 min at room temperature to obtain a mixed solution B; then 12 mmol of ammonium dihydrogen phosphate was added to the mixed solution B, stirred at 50 °C for 3 h, and then stirred at 88 °C for 3.5 h, and the solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C for 12 h to obtain the final V-PO 4 3- powder. Then the prepared V-PO 4 3- was calcined at 400 °C for 4 h and then at 750 °C for 8 h in a nitrogen atmosphere, and the heating rate was 5 °C·min -1 to obtain V 2 (PO 4 ) 3 three-dimensional honeycomb material. Finally, the prepared V 2 (PO 4 ) 3 was mixed with PVDF in a ratio of 9:1, uniformly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain the V 2 (PO 4 ) 3 electrode.

[0053] The V prepared in this comparative example 2 (PO 4 ) 3 The electrochemical performance of the electrode is as follows: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the symmetric cell assembled with it can stably cycle for 579 hours.

[0054] Comparative Example 2 18 mmol of anhydrous citric acid was added to 200 mL of deionized water and stirred at 500 r / min for 20 min at room temperature to obtain a mixed solution A; then 12 mmol of ammonium dihydrogen phosphate and 16 mmol of zinc nitrate hexahydrate were added to the mixed solution A, stirred at 50 °C for 3 h first, and then stirred at 88 °C for 3.5 h. The solvent was evaporated to obtain a blue gel-like substance. The prepared product was placed in a vacuum oven at 80 °C and dried for 12 h to obtain the final Zn-PO 4 3- powder. Then the prepared Zn-PO 4 3- Under a nitrogen atmosphere, it was first calcined at 400 °C for 4 h, and then calcined at 750 °C for 8 h, with a heating rate of 5 °C·min -1 to obtain Zn 3 (PO 4 ) 2 three-dimensional honeycomb material. Finally, the prepared Zn 3 (PO 4 ) 2 was mixed with PVDF in a ratio of 9:1, and it was uniformly spin-coated on a zinc foil with a thickness of 100 μm and a diameter of 1 cm, and dried in a vacuum oven at 80 °C for 12 h to obtain the Zn 3 (PO 4 ) 2 electrode.

[0055] The Zn prepared in this comparative example 3 (PO 4 ) 2 The electrochemical performance of the electrode is as follows: at a current density of 1 mA·cm -2 and an areal capacity of 1 mAh·cm -2 , the symmetric cell assembled with it can stably cycle for 583 hours.

[0056] Comparative Example 3 The difference from Example 1 is that the number of moles of ammonium metavanadate is 12 mmol and the number of moles of zinc nitrate hexahydrate is 8 mmol, to obtain Zn 1.2 V 0.8 (PO 4 ) 3Electrode.

[0057] The Zn prepared in this comparative example 1.2 V 0.8 (PO 4 ) 3 The electrochemical performance of the electrode is as follows: at a current density of 1 mA·cm -2 and a areal capacity of 1 mAh·cm -2 the symmetric cell assembled therefrom can be stably cycled for 453 hours.

[0058] Comparative Example 4 The method for assembling an aqueous zinc-ion symmetric button cell using an unmodified zinc foil electrode is different from that of Example 1 only in that: both the positive and negative electrode plates use unmodified zinc foil.

[0059] The electrochemical performance of the symmetric button cell obtained in this comparative example is as follows: at a current density of 1 mA·cm -2 and a areal capacity of 1 mAh·cm -2 it can be stably cycled for 175 hours.

[0060] Application Example Electrochemical Test The materials obtained in Examples 1 to 12 were used for electrochemical tests and compared with Comparative Examples 1 to 4. All electrochemical tests were completed in button cells.

[0061] The carbon paper and the unmodified zinc foil were cut into electrode sheet sizes using a cutting machine, and the M prepared in Examples 1 to 12 x V y (PO 4 ) 3 three-dimensional honeycomb materials and the materials prepared in Comparative Examples 1 to 3 were spin-coated on the unmodified zinc foil as the negative electrode, and the carbon paper coated with sodium vanadate was used as the positive electrode. 2M-ZnSO 4 was used as the electrolyte to assemble a button cell. The assembly method of the symmetric button cell in Comparative Example 4 was that both the positive and negative electrode plates used unmodified zinc foil. At a current density of 1 mA·cm -2 and a areal capacity of 1 mAh·cm -2 the cyclic charge-discharge test of the symmetric button cell was carried out as Figures 6 to 15 shown. Among them, the performance of Example 1 was the best, and its longest cycle life was 3457 h, greatly enhancing the cycle durability of the aqueous zinc-ion battery (as Figure 6 shown).

[0062] The Zn provided by the present invention 0.2 V 1.8 (PO 4 ) 3 coating-protected zinc negative electrode at a current density of 1 mA·cm -2The dough-making capacity is 1 mAh·cm -2 Under this condition, the assembled symmetric battery can stably cycle for 608 hours; the Zn 0.5 V 1.5 (PO 4 ) 3 coated zinc anode can stably cycle for 3457 hours at a current density of 1 mA·cm -2 and a dough-making capacity of 1 mAh·cm -2 Under this condition, the assembled symmetric battery can stably cycle for 1095 hours; the Zn 0.8 V 1.2 (PO 4 ) 3 coated zinc anode can stably cycle for 1095 hours at a current density of 1 mA·cm -2 and a dough-making capacity of 1 mAh·cm -2 Under this condition, the assembled symmetric battery can stably cycle for 1095 hours. Thus, the optimal molar mass ratio of the metal elements Zn and V is determined to be 1:2, and the optimal structural formula is Zn 0.5 V 1.5 (PO 4 ) 3 (space group is P21 / c). The Mg 0.5 V 1.5 (PO 4 ) 3 coated zinc anode can stably cycle for 833 hours at a current density of 1 mA·cm -2 and a dough-making capacity of 1 mAh·cm -2 Under this condition, the assembled symmetric battery can stably cycle for 833 hours; the Na 0.5 V 1.5 (PO 4 ) 3 coated zinc anode can stably cycle for 750 hours at a current density of 1 mA·cm -2 and a dough-making capacity of 1 mAh·cm -2 Under this condition, the assembled symmetric battery can stably cycle for 750 hours; the Li 0.5 V 1.5 (PO 4 ) 3 coated zinc anode can stably cycle for 728 hours at a current density of 1 mA·cm -2 and a dough-making capacity of 1 mAh·cm -2 Under this condition, the assembled symmetric battery can stably cycle for 728 hours; the cycle life is higher than that of the monovanadium-based phosphate V -2 at a current density of 1 mA·cm -2 and a dough-making capacity of 1 mAh·cm 2 (PO 4 ) 3The cycle life of the symmetric battery assembled with the zinc anode protected by the coating is 579 hours, with monophosphate Zn 3 (PO 4 ) 2 The cycle life of the symmetric battery assembled with the zinc anode protected by the coating is 453 hours, and the cycle life of the symmetric battery assembled with the unmodified zinc foil is 175 hours.

[0063] The above results show that the three-dimensional honeycomb-like binary vanadium-based phosphate anode protective layer material prepared in the present invention has a three-dimensional interconnected porous structure. When this material is applied to the aqueous zinc-ion battery, due to the synergistic effect of metal M and V, it can provide continuous ion / electron transfer, which is beneficial to regulating the electric field distribution, homogenizing the zinc ion flow, realizing the rapid transmission of zinc ions, improving the stability of the Zn metal anode electrode-electrolyte interface, and then improving the cycle life of the battery; the present invention promotes the research of the three-dimensional honeycomb-like binary vanadium-based phosphate anode protective layer material in the aqueous zinc-ion battery, which plays a certain role in promoting the development of high-cycle-life and green-safe aqueous zinc-ion batteries.

Claims

1. A use of a binary vanadium-based phosphate as an anode protective layer material in an aqueous zinc ion battery, characterized in that: The binary vanadium-based phosphate is M x V y (PO4)3, where M is Zn, Li, Na or Mg, 0 < x < 1, 1 < y < 2; the binary vanadium-based phosphate M x V y (PO4)3 is three-dimensional honeycomb-shaped; The electrolyte in the aqueous zinc ion battery is ZnSO4; The preparation method of the binary vanadium-based phosphate comprises: (1) Mix the complexing agent, phosphate and vanadium salt, and one or more of zinc salt, lithium salt, sodium salt or magnesium salt in a solvent, stir at room temperature and synthesize M,V-PO4 by sol-gel method. 3- , M is Zn, Li, Na or Mg; the vanadium salt is ammonium metavanadate; (2) Prepared M,V-PO4 3- Calcination under high temperature and nitrogen atmosphere to obtain a three-dimensional honeycomb M x V y (PO4)3, where 0 <x<1,1<y<2。 2. The use according to claim 1, characterized in that: The binary vanadium-based phosphate M x V y In (PO4)3: 0.2≤x≤0.8, 1.2≤y≤1.

8.

3. The use according to claim 1, characterized in that: The binary vanadium-based phosphate M x V y In (PO4)3: 0.5≤x≤0.8, 1.5≤y≤1.

2.

4. The use according to claim 1, characterized in that: The binary vanadium-based phosphate M x V y In (PO4)3, M is Zn.

5. The use according to claim 1, characterized in that: The binary vanadium-based phosphate M x V y (PO4)3 and PVDF were mixed and spin-coated on zinc foil as the negative electrode of aqueous zinc-ion batteries.

6. The use according to claim 5, characterized in that: The positive electrode in the aqueous zinc ion battery is a carbon paper coated with sodium vanadate.

7. The use according to claim 1, characterized in that: In step (1), 2 to 20 mmol of a complexing agent, 1 to 10 mmol of a vanadium salt, 1 to 14 mmol of a phosphate, and 1 to 18 mmol of a zinc salt, 1 to 18 mmol of a lithium salt, 1 to 18 mmol of a sodium salt or 1 to 18 mmol of a magnesium salt are added to a solvent, wherein the molar mass ratio of the vanadium salt to the zinc salt, lithium salt, sodium salt or magnesium salt is 1:1 to 4.

8. The use according to claim 7, characterized in that: In step (2), the M,V-PO4 prepared in step (1) 3- Calcinate at 300-900℃ in nitrogen atmosphere for 2-15h, with a heating rate of 2-7℃ min -1 .

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