A zinc ion battery dendrite-free anode and 3D printing preparation method thereof

Abstract

The present invention discloses a zinc ion battery dendrite-free anode and a 3D printing preparation method thereof, wherein the zinc ion battery dendrite-free anode is composed of zinc and stainless steel foil and a composite material coating deposited on one side of zinc and stainless steel foil, the composite material coating is a hollowed-out grid coating composed of a plurality of cross bars and a plurality of vertical bars uniformly staggered, and the composite material coating is printed with ink, and the ink includes N-methyl pyrrolidone and PC / SiOC composite material dissolved in N-methyl pyrrolidone, polyvinylidene fluoride and conductive carbon black, and the PC / SiOC composite material is composed of porous carbon and a silicon oxygen carbon network interpenetrating on porous carbon. The composite material coating of the present invention improves the transmission speed of zinc ions on the anode surface, and the anode also has the characteristics of high conductivity and high electrochemical activity, which improves the capacity and rate performance of the zinc ion battery, and the fast zinc ion transmission speed and large diffusion area can effectively inhibit dendrite growth, greatly improving the battery cycle life.

Description

Technical Field

[0001] The present invention relates to the technical field of zinc ion batteries, and in particular to a zinc ion battery dendrite-free anode and a 3D printing preparation method thereof. Background Art

[0002] In the context of the shortage of traditional energy resources and environmental pollution, the growing demand for consumer electronic products, the steady development of electric vehicles and the grid connection of renewable energy, people are increasingly demanding environmentally friendly energy storage devices with high energy density, recyclability, low cost and high reliability. Among various energy storage devices, lithium-ion batteries dominate the commercial secondary battery market due to their high energy density and long cycle life. However, lithium-ion batteries have inherent problems such as flammable organic electrolytes, the risk of short-circuit explosion caused by electrode dendrite growth, strict manufacturing and assembly requirements, and scarce lithium resources, which seriously affect their large-scale application. As an emerging and promising alternative energy storage technology, rechargeable aqueous zinc-ion batteries have great potential in portable electronic applications and large-scale energy storage systems due to their advantages such as high theoretical capacity (820mAh / g) of metallic zinc, low redox potential (-0.76Vvs.SHE), abundant reserves, simple manufacturing and assembly, low cost, safety and environmental protection, and have broad application prospects.

[0003] However, zinc-ion batteries face huge challenges in practical application. In particular, the dendrite growth of the metal zinc anode during the cyclic deposition / stripping process is the biggest problem limiting the application of zinc-ion batteries: dendrite growth will continuously consume water during the cycle and produce irreversible byproducts, resulting in low Coulombic efficiency, low capacity and limited cycle life of the zinc-ion battery; at the same time, as the dendrites grow, the surface area of ​​the anode increases, causing increased corrosion of the anode and other surface-related reactions, ultimately leading to continuous consumption of the anode and accelerated degradation of battery performance; more seriously, excessively long dendrites will penetrate the diaphragm and cause the battery to short-circuit and fail. In order to solve the problem of anode dendrite growth and improve the cycle life and rate performance of zinc ion batteries, people have developed a variety of zinc ion battery anode preparation methods that take into account the inhibition of dendrite growth. For example, Liu et al. developed a method of coating graphene oxide nanosheets on a zinc metal anode using a casting method to inhibit dendrite growth; invention application CN114094035A discloses a method for preparing an aluminum-zinc alloy coating on a zinc ion battery anode, which uses magnetron co-sputtering technology to prepare an aluminum-zinc alloy coating on the anode for anode protection; invention application CN112952052A provides a zinc / carbon nanotube foam composite material as an anode material for a zinc ion battery and discloses a method for preparing an anode using the composite material by high temperature reaction and electrodeposition in invention application CN112952053A.

[0004] However, the above-mentioned existing zinc ion battery anode preparation technology has the following disadvantages: the transmission speed of zinc ions on the anode surface is slow, and the electrical conductivity and electrochemical activity are not high, which limits the capacity and rate performance of the battery; the zinc ion diffusion area is limited and cannot completely inhibit the growth of dendrites, and there is still a risk of dendrites causing short circuits, which limits the cycle life; the preparation process is complex and the cost is high.

[0005] Therefore, the prior art still needs to be improved and developed. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a zinc ion battery dendrite-free anode and a 3D printing preparation method thereof, aiming to solve the problem that dendrites are easily grown on the surface of the existing zinc ion battery anode, resulting in poor battery capacity and rate performance and short cycle life.

[0007] The technical solution of the present invention is as follows:

[0008] A zinc ion battery dendrite-free anode, which is composed of zinc and stainless steel foil and a composite material coating deposited on one side of the zinc and stainless steel foil, wherein the composite material coating is a grid coating with a hollow center composed of a plurality of horizontal bars and a plurality of vertical bars evenly and staggered, and the composite material coating is formed by printing ink using low-temperature direct writing 3D printing technology, wherein the ink comprises N-methylpyrrolidone and a PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black dissolved in the N-methylpyrrolidone, and the PC / SiOC composite material is composed of porous carbon and a silicon-oxygen-carbon network interpenetrating on the porous carbon.

[0009] The zinc ion battery dendrite-free anode, wherein the middle hollow is a square hollow, and the side length of the square hollow is equal to the line width of the horizontal rod and the vertical rod.

[0010] The zinc ion battery dendrite-free anode, wherein the horizontal bar and the vertical bar have the same size, and the line width is 400-420 μm.

[0011] The zinc ion battery dendrite-free anode has a thickness of 0.1 mm for the zinc and stainless steel foils and a thickness of 500-550 μm for the composite material coating.

[0012] The zinc ion battery dendrite-free anode, wherein in the ink, the mass ratio of the PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black is 8:1:1.

[0013] A 3D printing preparation method for a zinc ion battery dendrite-free anode, comprising the steps of:

[0014] The PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black are ball-milled and dissolved in N-methylpyrrolidone to obtain an ink composition, wherein the PC / SiOC composite material is composed of porous carbon and a silicon-oxygen-carbon network interpenetrating on the porous carbon;

[0015] removing lumps and large particles in the ink composition by vacuum filtration, and allowing the composition to stand at room temperature for a predetermined time to obtain ink;

[0016] The ink was printed on one side of zinc and stainless steel foil using low-temperature direct writing 3D printing technology, and after vacuum drying, a dendrite-free anode for zinc ion batteries was obtained.

[0017] The 3D printing preparation method of the zinc ion battery dendrite-free anode, wherein the ink is printed on one side of zinc and stainless steel foil by low-temperature direct writing 3D printing technology, and after vacuum drying, the steps of preparing the zinc ion battery dendrite-free anode include:

[0018] The ink is loaded into a syringe needle tube connected to a lockable stainless steel blunt nozzle, and the ink in the syringe needle tube is squeezed out through the lockable stainless steel blunt nozzle and printed on one side of the zinc and stainless steel foils to obtain an anode in an uncured state of the composite material coating;

[0019] The anode in the uncured state of the composite material coating is placed in a vacuum oven, the temperature of the vacuum oven is set to 80° C., and maintained for 12 hours to obtain a zinc ion battery dendrite-free anode.

[0020] The 3D printing preparation method of the zinc ion battery dendrite-free anode, wherein during the printing process, the ink flow rate and the printing speed are controlled to be 18 mm / s.

[0021] The 3D printing preparation method of the zinc ion battery dendrite-free anode, wherein the preparation of the PC / SiOC composite material comprises the steps of:

[0022] Preparation of isoreticular covalently functionalized zirconium-based MOF crystals, namely UiO-66-NH2 crystals;

[0023] Dissolving hexadecyltrimethylammonium bromide in a PDSDA methanol solution in an ultrasonic bath to obtain a PDSDA / CTAB mixed solution; dissolving the UiO-66-NH2 crystals in methanol under magnetic stirring to obtain a UiO-66-NH2 solution;

[0024] The PDSDA / CTAB mixed solution is added to the UiO-66-NH2 solution in an argon environment, stirred at room temperature, and then after the polymerization reaction in MOFs is completed, argon degassing, sample collection, ethanol washing and vacuum drying are performed to obtain a UiO-66 / PDSDA synthetic material;

[0025] The UiO-66 / PDSDA composite was placed in a tubular furnace and subjected to a three-stage pyrolysis process in an argon environment: in the first stage, the temperature was increased from 25°C to 400°C at a heating rate of 2°C / min, and then maintained at 400°C for two hours; in the second stage, the temperature was increased from 200°C to 800°C at a heating rate of 2°C / min, and maintained at 800°C for four hours; in the third stage, the temperature was reduced from 800°C to room temperature at a cooling rate of 2°C / min.

[0026] The 3D printing preparation method of the zinc ion battery dendrite-free anode, wherein the preparation of the UiO-66-NH2 crystal comprises the steps of:

[0027] Dissolve ZrCl4 and H2N-H2BDC in HCON(CH3)2 at the same concentration of 0.02mol / L-0.025mol / L, then add hydrochloric acid, the volume ratio of hydrochloric acid to HCON(CH3)2 is 1:140, to obtain a mixed solution;

[0028] After stirring the mixed solution at room temperature for 30 minutes, the mixed solution was transferred to a polytetrafluoroethylene-lined high-pressure reactor and heated at 120°C for 10 hours. After heating, the suspension was centrifuged to obtain a yellow powder product, which was subsequently washed with anhydrous ethanol and then transferred to a Schlenk flask and dried at ambient temperature to obtain UiO-66-NH2 crystals.

[0029] Beneficial effects: Compared with the prior art, the zinc ion battery dendrite-free anode prepared by the present invention has the advantages of fast zinc ion transmission speed on the anode surface, high conductivity and electrochemical activity, high battery capacity and rate performance, large zinc ion diffusion area, which can effectively inhibit dendrite growth and greatly improve cycle life, and the preparation process of the zinc ion battery dendrite-free anode of the present invention is simple and low in cost. The anode prepared by the present invention achieves an excellent capacity of 99 mAh / g for more than 500 cycles at a current density of 0.45 A / g in a half-cell, and the coulombic efficiency is as high as 99.98%; a complete zinc ion battery constructed by using the anode prepared by the present invention still has a high capacity of 67 mAh / g after 2453 cycles at a current density of 0.5 A / g, has good cycle life and rate performance, is of great significance to the development of dendrite-free zinc ion batteries, and has high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a three-dimensional diagram of a dendrite-free anode for a zinc ion battery according to the present invention.

[0031] Figure 2 The present invention is a front view of a dendrite-free anode of a zinc ion battery.

[0032] Figure 3 The present invention is a flow chart of a 3D printing preparation method for a zinc ion battery dendrite-free anode.

[0033] Figure 4 Schematic diagram of the chemical reaction principle of the PC / SiOC composite material in the present invention.

[0034] Figure 5 a is a SEM image of the PC / SiOC composite material obtained in Example 1 of the present invention; b is a SEM image of the UiO-66-NH2 crystal obtained in Example 1 of the present invention; c is a SEM image of the PC alone in Example 1 of the present invention.

[0035] Figure 6 a is a TEM image of the PC / SiOC composite material obtained in Example 1 of the present invention; b is a high-resolution TEM image of the PC / SiOC composite material obtained in Example 1 of the present invention.

[0036] Figure 7 Schematic diagram of cycle life and rate characteristics at a current density of 0.45 A / g in half-cell state of Example 2 of the present invention and Comparative Example 1;

[0037] Figure 8 Schematic diagram of cycle life and rate characteristics at a current density of 0.45 A / g in the half-cell state of Comparative Examples 2 and 3 of the present invention;

[0038] Fig. 9 Schematic diagram of cycle life and rate characteristics at a current density of 0.5 A / g in the complete battery state of Example 2, Comparative Example 2 and Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0039] The present invention provides a zinc ion battery dendrite-free anode and a 3D printing preparation method thereof. In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] See also Figure 1The present invention provides a dendrite-free anode for a zinc ion battery, as shown in the figure, which is composed of a zinc and stainless steel foil 1 and a composite material coating 2 deposited on one side of the zinc and stainless steel foil 1, wherein the composite material coating 2 is a grid coating with a middle hollow 21 composed of a plurality of horizontal bars and a plurality of vertical bars uniformly and staggeredly arranged, and the composite material coating 2 is formed by printing ink using a low-temperature direct writing 3D printing technology, wherein the ink comprises N-methylpyrrolidone and a PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black dissolved in the N-methylpyrrolidone, wherein the PC / SiOC composite material is composed of porous carbon and a silicon-oxygen-carbon network interpenetrating the porous carbon.

[0041] Specifically, the PC / SiOC composite material of the present invention has an electrode-optimized three-dimensional grid structure, which can quickly reverse, carry and guide divalent zinc ions while limiting the direct contact between the organic electrolyte and the anode. In addition, the PC / SiOC composite material has strong molecular coordination, which can provide a larger rapid diffusion area for zinc ions to effectively control dendrite growth. Based on this, the present invention prepares the PC / SiOC composite material into ink, and uses low-temperature direct writing 3D printing technology to print the ink into a film on the surface of the zinc ion battery anode, which can not only improve the transmission speed of zinc ions on the anode surface, but also the film has the characteristics of high conductivity and high electrochemical activity, which improves the capacity and rate performance of the zinc ion battery, and the fast zinc ion transmission speed and large diffusion area can effectively inhibit dendrite growth and greatly improve the functional requirements of cycle life; the anode prepared by the present invention achieves an excellent capacity of 99mAh / g for more than 500 cycles at a current density of 0.45A / g in a half-cell, and the coulombic efficiency is as high as 99.98%; the anode prepared by the present invention is used to construct a complete zinc ion battery, which still has a high capacity of 67mAh / g after 2453 cycles at a current density of 0.5A / g, has a good cycle life and rate performance, is of great significance to the development of dendrite-free zinc ion batteries, and has high practicality.

[0042] In this embodiment, by printing the composite material coating 2 into a grid coating with a hollow middle 21, the surface area of ​​the composite material coating is increased macroscopically, that is, the diffusion area of ​​zinc ions is increased, thereby further effectively inhibiting the growth of dendrites. In other words, the zinc ion battery dendrite-free anode provided by the present invention increases the diffusion area of ​​zinc ions from both macroscopic and microscopic aspects, and at the same time increases the transmission speed of zinc ions, so that dendrite growth can be inhibited to the greatest extent, thereby improving the functional requirements of high cycle life of the battery.

[0043] In some embodiments, Figure 1-2As shown, the middle hollow is a square hollow, and the side length of the square hollow is equal to the line width of the horizontal and vertical bars. In order to ensure that the grid coating formed by printing has the largest surface area and avoid adhesion between adjacent horizontal bars or adjacent vertical bars during the printing process, this embodiment ensures that the side length of the square hollow is equal to the line width of the horizontal and vertical bars during the printing process. In this embodiment, the horizontal and vertical bars are the same size, and the line width is 400-420μm. As an example, Figure 2 As shown, the line widths of the horizontal bars and the vertical bars are both 409 μm, and the side length of the square hollow is also 409 μm.

[0044] In some embodiments, the thickness of the zinc and stainless steel foil is 0.1 mm, and the thickness of the composite coating is 500-550 μm. For example, the thickness of the composite coating can be 500 μm, 510 μm, 520 μm, 528 μm, 530 μm, 540 μm, 550 μm, etc.

[0045] In some embodiments, the mass ratio of the PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black is 8:1:1.

[0046] In some embodiments, a 3D printing method for preparing a dendrite-free anode for a zinc ion battery is also provided. Figure 3 As shown, it includes the steps of:

[0047] S10, ball-milling a PC / SiOC composite material, polyvinylidene fluoride, and conductive carbon black, and then dissolving the resultant in N-methylpyrrolidone to obtain an ink composition, wherein the PC / SiOC composite material is composed of porous carbon and a silicon-oxygen-carbon network interpenetrating on the porous carbon;

[0048] S20, removing lumps and large particles in the ink composition by vacuum filtration, and leaving the composition to stand at room temperature for a predetermined time to obtain ink;

[0049] S30, using low-temperature direct writing 3D printing technology to print the ink on one side of zinc and stainless steel foil, and after vacuum drying, a dendrite-free anode for a zinc ion battery is obtained.

[0050] The preparation process of the zinc ion battery dendrite-free anode provided in this embodiment has the advantages of simple operation and low cost. The prepared ion battery dendrite-free anode has fast zinc ion transmission speed on the anode surface, high conductivity and electrochemical activity, high battery capacity and rate performance, large zinc ion diffusion area, which can effectively inhibit dendrite growth and greatly improve cycle life. The preparation process of the zinc ion battery dendrite-free anode in the embodiment has the advantages of simple cost and low cost. The anode prepared by this embodiment achieves an excellent capacity of 99mAh / g for more than 500 cycles at a current density of 0.45A / g in a half-cell, and the coulombic efficiency is as high as 99.98%; the anode prepared by the present invention is used to construct a complete zinc ion battery, which still has a high capacity of 67mAh / g after 2453 cycles at a current density of 0.5A / g, has a good cycle life and rate performance, is of great significance to the development of dendrite-free zinc ion batteries, and has high practicality.

[0051] In this embodiment, the ink has good viscosity characteristics, shear thinning characteristics, and shape retention characteristics. The anode surface coating obtained by using the ink has high dimensional accuracy, a smooth surface, and good printability.

[0052] In some embodiments, the ink is printed on one side of zinc and stainless steel foil using low-temperature direct writing 3D printing technology, and after vacuum drying, the step of preparing a dendrite-free anode for a zinc ion battery includes: gently stirring the ink, and then loading it into a 10mL syringe needle connected to a lockable stainless steel blunt nozzle with an inner diameter of 200μm, and then using computer-aided design software SolidWorks Corporation to control the ink flow rate and printing speed in the low-temperature direct writing 3D printer to be 18mm / s, and the ink in the syringe needle is extruded through the lockable stainless steel blunt nozzle and printed on one side of the zinc and stainless steel foil to obtain an anode in an uncured state of the composite material coating; placing the anode in the uncured state of the composite material coating in a vacuum oven, setting the temperature of the vacuum oven to 80°C and maintaining it for 12 hours to obtain a cured anode product.

[0053] In some embodiments, the preparation of the PC / SiOC composite material includes the steps of: dissolving ZrCl4 and H2N-H2BDC in HCON(CH3)2 at the same concentration of 0.02mol / L-0.025mol / L, and then adding hydrochloric acid, the volume ratio of hydrochloric acid to HCON(CH3)2 is 1:140, to obtain a mixed solution; after stirring the mixed solution at room temperature for 30 minutes, transferring the mixed solution to a polytetrafluoroethylene-lined high-pressure reactor and heating it at 120°C for 10 hours, and after heating, centrifuging the suspension to obtain a yellow powder product, then washing it with anhydrous ethanol, and then transferring it to a Schlenk bottle and drying it at ambient temperature to obtain UiO-66-NH 2 crystals; dissolving hexadecyltrimethylammonium bromide (CTAB) in a PDSDA (poly[(silyl)diacetylene]) methanol solution in an ultrasonic bath to obtain a PDSDA / CTAB mixed solution; dissolving the UiO-66-NH2 crystals in methanol under magnetic stirring to obtain a UiO-66-NH2 solution; adding the PDSDA / CTAB mixed solution to the UiO-66-NH2 solution in an argon environment, stirring at room temperature, and then performing argon degassing, sample collection, ethanol washing and vacuum drying after the polymerization reaction in MOFs is completed to obtain a UiO-66 / PDSDA composite; the UiO-66 / PDSDA The synthesis was placed in a tubular furnace and subjected to a three-stage pyrolysis process in an argon environment: in the first stage, the temperature was increased from 25°C to 400°C at a heating rate of 2°C / min, and then maintained at 400°C for two hours; in the second stage, the temperature was increased from 200°C to 800°C at a heating rate of 2°C / min, and maintained at 800°C for four hours; in the third stage, the temperature was reduced from 800°C to room temperature at a cooling rate of 2°C / min to obtain a PC / SiOC composite material.

[0054] Specifically, if Figure 4As shown, in this embodiment, UiO-66-NH2 crystals are first prepared, and then the PDSDA / CTAB mixed solution is stirred and mixed with the UiO-66-NH2 solution. In this process, the linear PDSDA can react with the -NH2 on the UiO-66-NH2 crystal, so that the PDSDA is combined with the UiO-66-NH2 crystal to generate a UiO-66 / PDSDA composite. Finally, the UiO-66 / PDSDA composite is subjected to a pyrolysis treatment. In the first stage, a polymerization reaction can occur between multiple PDSDAs in the UiO-66 / PDSDA composite, and / or The PDSDA between adjacent UiO-66 / PDSDA composites can undergo polymerization reaction, so that the PDSDA on UiO-66 forms a cross-linked network; in the second stage, high-temperature heating causes the Si-C bonds in the cross-linked network PDSDA to break, thereby forming a SiOC network, and the SiOC network is interpenetrated on the porous carbon matrix to form the PC / SiOC composite material. The matrix of the PC / SiOC composite material is the MOF framework. The composite network SiOC structure expands the specific surface area, conductivity, electrochemical activity, etc. of the material, which makes the material have great advantages in the application of zinc ion battery anode.

[0055] In this embodiment, the CTAB, as a surfactant, helps to destroy the polymerization attraction between the PDSDA polymer chains themselves, so that the PDSDA polymer chains can be better composited to the MOF framework to form a UiO-66 / PDSDA composite.

[0056] In this embodiment, in the PDSDA / CTAB mixed solution, the concentration of PDSDA is 0.01 g / mL, and the concentration of CTAB is 0.005 g / mL; the concentration of the UiO-66-NH2 solution is 0.01455 g / mL; the mass ratio of the PDSDA / CTAB mixed solution to the UiO-66-NH2 solution is 1:3.

[0057] The present invention is further explained below by specific embodiments:

[0058] Example 1

[0059] A 3D printing method for preparing a dendrite-free anode for a zinc ion battery is provided, which comprises the following steps:

[0060] S1. Prepare a composite material for an anode, the specific operation is as follows:

[0061] S101, 1.50g, 6.4mmol of ZrCl4 and 1.56g, 6.4mmol of H2N-H2BDC were dissolved in 280mL of HCON(CH3)2, and then 2mL of 36wt% hydrochloric acid was added, so that the volume ratio of hydrochloric acid to HCON(CH3)2 was 1:140, and the concentrations of ZrCl4 and H2N-H2BDC were both 0.023mol / L, within the range of 0.02mol / L-0.025mol / L; then the mixed solution was stirred at room temperature for thirty minutes, and then the mixture was transferred to a 500mL polytetrafluoroethylene-lined autoclave and heated at 120°C for ten hours. After heating, a yellow powder product was obtained by centrifuging the suspension, which was then washed with anhydrous ethanol, and then transferred to a Schlenk flask and dried at ambient temperature to obtain UiO-66-NH2 crystals;

[0062] S102, dissolving 0.5 g of CTAB in a 100 mL PDSDA-methanol solution with a concentration of 0.01 g / mL in an ultrasonic bath to perform polymerization reaction to obtain a PDSDA / CTAB mixed solution, so that the concentration of CTAB in the mixed solution is 0.005 g / mL; dissolving 1.455 g of the UiO-66-NH2 crystals obtained in step S101 in 100 mL of methanol in a Schlenk bottle under magnetic stirring to obtain a UiO-66-NH2 solution with a concentration of 0.01455 g / L;

[0063] S103, the PDSDA / CTAB mixed solution obtained in step S102 is quickly immersed in a Schlenk bottle containing the UiO-66-NH2 solution obtained in S102 in an argon environment at a mass ratio of 1:3, firstly vigorously stirred at room temperature for thirty minutes, then the polymerization reaction in MOFs is completed for three hours, then the Schlenk bottle is degassed with argon, and then the sample is collected using a rotary evaporator, washed with ethanol, and finally dried in a vacuum oven set at 80° C. overnight to obtain a UiO-66 / PDSDA composite;

[0064] S104. The UiO-66 / PDSDA composition obtained in step S103 is placed in a tubular furnace and subjected to a three-stage pyrolysis process in an argon environment: in the first stage, the temperature is increased from 25°C to 400°C at a heating rate of 2°C / min, and then maintained at 400°C for two hours; in the second stage, the temperature is increased from 200°C to 800°C at a heating rate of 2°C / min, and maintained at 800°C for four hours; in the third stage, the temperature is reduced from 800°C to room temperature at a cooling rate of 2°C / min.

[0065] S2. Prepare anode composite material coating ink suitable for 3D printing, the specific operation is as follows:

[0066] S201, firstly, uniformly mixing the PC / SiOC composite material obtained in step S1 with PVDF and conductive carbon black at a mass ratio of 8:1:1 by planetary ball milling, and then dissolving the mixed powder in an NMP solution to obtain a homogeneous ink composition;

[0067] S202, removing lumps and large particles from the ink composition in step S201 by vacuum filtration to prevent nozzle clogging, and then standing at room temperature for twelve hours to obtain a stable anode composite coating ink suitable for 3D printing.

[0068] S3. Use low-temperature direct writing 3D printing to print ink on one side of the zinc and stainless steel foils. The specific operations are as follows:

[0069] The ink obtained in step S2 was gently stirred, and then loaded into a 10 mL syringe needle connected to a lockable stainless steel blunt nozzle with an inner diameter of 200 μm, and then the ink flow rate and printing speed in the low-temperature direct writing 3D printer were controlled to be 18 mm / s using computer-aided design software SolidWorks Corporation, and the ink in the syringe needle was extruded through the lockable stainless steel blunt nozzle and printed on one side of the zinc and stainless steel foils to obtain an anode in an uncured state of the composite material coating;

[0070] S4. Place the 3D printed anode into a vacuum oven for drying to obtain a cured anode product. The specific operation is as follows: place the anode in an uncured state of the composite material coating obtained in step S3 into a vacuum oven, set the temperature of the vacuum oven to 80° C., and keep the temperature for 12 hours to obtain a cured anode product.

[0071] Example 2

[0072] The anode obtained in Example 1 was used as the negative electrode of the battery, a 2400 porous polypropylene separator with a thickness of 25 μm produced by Celgard Company of the United States was used as the diaphragm, 3M ZnSO4 deionized water was used as the electrolyte, and a V2O5 flat plate coated with V2O5 / C was used as the positive electrode of the battery to build a half-cell (denoted as CE 3DP-PC / SiOC) and a complete cell (denoted as V2O5 / C|3DP-PC / SiOC@Zn).

[0073] In order to verify the cycle life and rate performance of the anode prepared by the method proposed in the present invention, a comparative example was set up to compare the electrical performance of the half-cell and the complete cell in Example 2. The comparative example was set up as follows:

[0074] Comparative Example 1

[0075] In Comparative Example 1, the anode preparation process is compared with the process in Example 1, lacking step S102 and step S103, that is, directly entering step S104 from step S101, putting the UiO-66-NH2 crystals obtained in step S101 into a tube furnace for step S104, and the other steps are the same as in Example 1 to obtain the anode, and the obtained anode is used as the negative electrode of the battery, a 2400 porous, 25 μm thick polypropylene separator produced by Celgard Company of the United States is used as a diaphragm, 3M ZnSO4 deionized water is used as the electrolyte, and a V2O5 / C flat plate coated with a V2O5 flat plate is used as the positive electrode of the battery to build a half-cell and a complete battery.

[0076] Comparative Example 2

[0077] In Comparative Example 2, the anode preparation process is compared with the process in Example 1. In step S3, the ink is horizontally coated on one side of the zinc and stainless steel foils, instead of using low-temperature direct writing 3D printing technology to print the ink on one side of the zinc and stainless steel foils. The other steps are the same as in Example 1 to obtain the anode, and the obtained anode is used as the negative electrode of the battery. A 2400 porous, 25 μm thick polypropylene separator produced by Celgard Company of the United States is used as a diaphragm, 3M ZnSO4 deionized water is used as an electrolyte, and a V2O5 / C flat plate coated with a V2O5 flat plate is used as the positive electrode of the battery to build a half-cell and a complete battery.

[0078] Comparative Example 3

[0079] In Comparative Example 3, the anode preparation process lacks step S102 and step S103 compared to the process in Example 1, that is, step S104 is directly entered from step S101, the UiO-66-NH2 crystal obtained in step S101 is placed in a tube furnace for step S104, and at the same time, in step S3, the ink is horizontally coated on one side of the zinc and stainless steel foils, instead of using low-temperature direct writing 3D printing technology to print the ink on one side of the zinc and stainless steel foils. The other steps are the same as in Example 1 to obtain the anode, and the obtained anode is used as the negative electrode of the battery, and a 2400 porous, 25 μm thick polypropylene separator produced by Celgard Company of the United States is used as a diaphragm, 3MZnSO4 deionized water is used as the electrolyte, and a V2O5 / C flat plate coated with a V2O5 flat plate is used as the positive electrode of the battery to build a half-cell and a complete battery.

[0080] Comparative Example 4

[0081] In Comparative Example 4, 0.1 mm thick zinc and stainless steel foil without any coating was directly used as the anode as the negative electrode of the battery, a 2400 porous, 25 μm thick polypropylene separator from Celgard Company of the United States was used as the diaphragm, 3M ZnSO4 deionized water was used as the electrolyte, and a V2O5 / C flat plate coated with a V2O5 flat plate was used as the positive electrode to build a complete battery.

[0082] First, the structural properties of the PC / SiOC composite material prepared by the present invention were verified. The PC / SiOC composite material prepared in Example 1 was characterized in terms of material morphology and structure using a scanning electron microscope (SEM) of model JEOL-6700 and a transmission electron microscope (TEM) of model JEOL-2100F. During the SEM analysis, an energy dispersive X-ray spectrometer was used to perform dispersion spectrum analysis (EDS) to obtain detailed information on the element distribution and phase structure of the composite material. The results are as follows: Figure 5 (a) is a SEM image of the PC / SiOC composite material, showing that the spherical particle size of the carbon shell containing ZrO2 in the composite material is about 100nm. Figure 5 (b) is a SEM image of the UiO-66-NH2 crystal obtained in step S1 of Example 1, Figure 5 (c) is the SEM image of PC alone, compared with the attached Figure 5 (a) and (c) Figure 5 (b) and Figure 5 (c) shows that the morphology of the PC / SiOC composite material after polymerization and pyrolysis is consistent with the initial UiO-66-NH2 crystal morphology; Figure 6 (a) is a TEM image of the PC / SiOC composite, indicating that the PC / SiOC composite retains the structure of the parent UiO-66-NH2 crystal, has retained porosity and is coordinated with the SiOC network interpenetrating with the PC surface, and creates a large number of active sites for ion storage; Figure 6 (b) is a high-resolution TEM image of the PC / SiOC composite material, indicating that the PC / SiOC composite material has obvious screw dislocations, particle clusters and grain boundaries, which are derived from the SiOC coordination between ZrO2 crystals in different adjacent shells, and the interpenetrating SiOC network in PC can be used as a conductive network to create more active sites and improve the charge transfer performance; the structural performance test of the PC / SiOC composite material shows that: the PC / SiOC composite material in Example 1 obtained by the present invention has an electrode-optimized three-dimensional grid structure, which can quickly reverse, carry and guide divalent zinc ions, while limiting the direct contact between the organic electrolyte and the anode, and has strong molecular coordination, which can provide a larger rapid diffusion area for zinc ions to effectively control dendrite growth.

[0083] Secondly, the half-cells and complete cells in Example 2 and each comparative example were subjected to electrical performance testing and comparison, and rate capacity and cycle performance tests were performed using a battery tester model LANHE-CT2001A of Wuhan Shenglan Electronic Technology Co., Ltd. The test and comparison results are as follows:

[0084] Compare the rate capacity and cycle performance test results under half-battery: see the attached Figure 7 and attached Figure 8 The anode prepared by the present invention achieved an excellent capacity of 99 mAh / g after 500 cycles at a current density of 0.45 A / g in the half-cell of Example 2, and the coulombic efficiency was as high as 99.98% (see Appendix Figure 7 ); In contrast, the half-cell of Comparative Example 1 maintained a capacity of 72 mAh / g after 500 cycles at a current density of 0.45 A / g, and the coulombic efficiency was 98.29% (Appendix Figure 7 ); Comparative Example 2 half-cell maintained a capacity of 82 mAh / g after 100 cycles at a current density of 0.45 A / g, and a coulombic efficiency of 97% (attached Figure 8 ); The half-cell of Comparative Example 3 maintained a capacity of 35 mAh / g after 65 cycles at a current density of 0.45 A / g, and the coulombic efficiency was 96% (attached Figure 8 );

[0085] Then, compare the rate capacity and cycle performance test results of the complete battery: see Appendix Fig. 9 , a complete zinc ion battery constructed by using the anode prepared by the present invention still has a high capacity of 67 mAh / g after 2453 cycles at a current density of 0.5 A / g; in contrast, the number of complete battery cycles in comparative example 2 is 1880 times, and the capacity is 58 mAh / g; the number of complete battery cycles in comparative example 4 is 128 times, and the capacity is 13 mAh / g. Therefore, the comparison between the embodiment and the comparative example proves that the anode prepared by the method proposed by the present invention has excellent cycle life and rate performance, which is of great significance to the development of dendrite-free zinc ion batteries and has high practicality.

[0086] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A zinc ion battery dendrite-free anode, characterized in that: The invention is composed of zinc and stainless steel foil and a composite material coating deposited on one side of the zinc and stainless steel foil. The composite material coating is a grid coating with a hollow middle composed of a plurality of horizontal bars and a plurality of vertical bars evenly and staggered. The composite material coating is formed by printing ink using low-temperature direct writing 3D printing technology. The ink includes N-methylpyrrolidone and a PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black dissolved in the N-methylpyrrolidone. The PC / SiOC composite material is composed of porous carbon and a silicon-oxygen-carbon network interpenetrating the porous carbon. The PC / SiOC composite material has strong molecular coordination and provides a larger rapid diffusion area for zinc ions.

2. The zinc ion battery dendrite-free anode according to claim 1, characterized in that The middle hollow is a square hollow, and the side length of the square hollow is equal to the line width of the horizontal rod and the vertical rod.

3. The zinc ion battery dendrite-free anode according to claim 2, characterized in that The horizontal bars and vertical bars have the same size, and the line width is 400-420µm.

4. The zinc ion battery dendrite-free anode according to claim 1, characterized in that The zinc and stainless steel foils have a thickness of 0.1 mm and the composite coating has a thickness of 500-550 µm.

5. The zinc ion battery dendrite-free anode according to claim 1, characterized in that In the ink, the mass ratio of the PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black is 8:1:

1.

6. A 3D printing method for preparing a dendrite-free anode for a zinc ion battery as claimed in claim 1, characterized in that: Includes steps: The PC / SiOC composite material, polyvinylidene fluoride and conductive carbon black are ball-milled and dissolved in N-methylpyrrolidone to obtain an ink composition, wherein the PC / SiOC composite material is composed of porous carbon and a silicon-oxygen-carbon network interpenetrating on the porous carbon; removing lumps and large particles in the ink composition by vacuum filtration, and allowing the composition to stand at room temperature for a predetermined time to obtain ink; The ink was printed on one side of zinc and stainless steel foil using low-temperature direct writing 3D printing technology, and after vacuum drying, a dendrite-free anode for zinc ion batteries was obtained.

7. The 3D printing method for preparing a dendrite-free anode for a zinc ion battery according to claim 6, characterized in that: The steps of printing the ink on one side of zinc and stainless steel foil by low-temperature direct writing 3D printing technology and preparing the dendrite-free anode of zinc ion battery after vacuum drying include: The ink is loaded into a syringe needle tube connected to a lockable stainless steel blunt nozzle, and the ink in the syringe needle tube is squeezed out through the lockable stainless steel blunt nozzle and printed on one side of the zinc and stainless steel foils to obtain an anode in an uncured state of the composite material coating; The anode in the uncured state of the composite material coating is placed in a vacuum oven, the temperature of the vacuum oven is set to 80° C., and maintained for 12 hours to obtain a zinc ion battery dendrite-free anode.

8. The 3D printing method for preparing a dendrite-free anode for a zinc ion battery according to claim 7, characterized in that: During the printing process, the ink flow rate and printing speed were controlled to be 18 mm / s.

9. The 3D printing method for preparing a dendrite-free anode for a zinc ion battery according to claim 6, characterized in that: The preparation of the PC / SiOC composite material comprises the following steps: Preparation of isoreticular covalently functionalized zirconium-based MOF crystals, namely UiO-66-NH2 crystals; Dissolving hexadecyltrimethylammonium bromide in a PDSDA methanol solution in an ultrasonic bath to obtain a PDSDA / CTAB mixed solution; dissolving the UiO-66-NH2 crystals in methanol under magnetic stirring to obtain a UiO-66-NH2 solution; The PDSDA / CTAB mixed solution is added to the UiO-66-NH2 solution in an argon environment, stirred at room temperature, and then after the polymerization reaction in MOFs is completed, argon degassing, sample collection, ethanol washing and vacuum drying are performed to obtain a UiO-66 / PDSDA synthetic material; The UiO-66 / PDSDA composite was placed in a tubular furnace and subjected to a three-stage pyrolysis process in an argon environment: in the first stage, the temperature was increased from 25°C to 400°C at a heating rate of 2°C / min, and then maintained at 400°C for two hours; in the second stage, the temperature was increased from 200°C to 800°C at a heating rate of 2°C / min, and maintained at 800°C for four hours; in the third stage, the temperature was reduced from 800°C to room temperature at a cooling rate of 2°C / min.

10. The 3D printing preparation method of the zinc ion battery dendrite-free anode according to claim 9, characterized in that: The preparation of the UiO-66-NH2 crystal comprises the following steps: Dissolve ZrCl4 and H2N-H2BDC in HCON(CH3)2 at the same concentration of 0.02mol / L-0.025mol / L, then add hydrochloric acid, the volume ratio of hydrochloric acid to HCON(CH3)2 is 1:140, to obtain a mixed solution; After stirring the mixed solution at room temperature for 30 minutes, the mixed solution was transferred to a polytetrafluoroethylene-lined high-pressure reactor and heated at 120°C for 10 hours. After heating, the suspension was centrifuged to obtain a yellow powder product, which was subsequently washed with anhydrous ethanol and then transferred to a Schlenk flask and dried at ambient temperature to obtain UiO-66-NH2 crystals.

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