Copper permeation doped zinc metal negative electrode material for zinc ion battery and preparation method and application of copper permeation doped zinc metal negative electrode material

Abstract

The invention discloses a copper permeation doped zinc metal negative electrode material for a zinc ion battery and a preparation method and application thereof, and belongs to the field of battery materials. The preparation method of the negative electrode material comprises the following steps: stacking the copper foil and the zinc foil together, enabling the smooth surface of the copper foil to be in contact with the zinc foil, then rolling the copper foil into a cylindrical shape, fixing the copper foil, and calcining the cylindrical copper foil and the zinc foil under protective gas to obtain the copper-permeable zinc-doped metal negative electrode material. The preparation method is simple in process, copper atoms permeate into zinc metal through heating, the smooth surface of the zinc metal is changed into uniform particles, zinc ions are not prone to concentrated deposition due to the structure of the zinc metal, the phenomena of point effect generation and uneven charge deposition are avoided, the problem that dendritic crystals pierce the diaphragm can be effectively prevented, and the service life of the diaphragm is prolonged. Meanwhile, the polarization voltage of the battery is reduced and the cycling stability of the battery is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of battery materials, in particular to a copper-permeated doped zinc metal negative electrode material for a zinc ion battery and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of economy and technology, the problem of gradual depletion of fossil energy is increasingly prominent, so it is urgent to research, develop and utilize efficient and clean renewable energy. Among many renewable energies, the technical development of lithium ion batteries is limited by potential safety hazards and the reduction of lithium resources. Among other alkali metals, metal zinc (Zn) stands out due to its high theoretical capacity (820 mAh / g), low plating / delamination potential (-0.76 V vs. standard hydrogen electrode), easy processing and other advantages. Zinc ion batteries also exhibit excellent safety performance, which is one of the effective ways to solve the energy crisis and environmental problems. However, due to the safety problems of flammability, corrosion and poor thermal stability of organic electrolyte, the development of traditional zinc ion batteries is limited. Compared with the traditional zinc ion battery, the aqueous zinc ion battery (AZIB) is considered to be the preferred direction of the next generation of new energy storage batteries due to its high safety and high energy density, laying the foundation for zinc ion batteries as a future research direction.

[0003] Zinc is an amphoteric metal with relatively active chemical properties, which will react in both acidic and alkaline environments. Even in a mild aqueous neutral electrolyte, problems of dendrite growth and "dead zinc" will occur. The growth of zinc dendrites not only pierces the separator to cause short circuit of the battery, but also increases the specific surface area of the negative electrode, accelerates the corrosion and hydrogen evolution rate, resulting in low utilization rate and coulombic efficiency of the negative electrode. In addition, due to the poor adhesion between dendrites and metal, "dead zinc" is easily formed by falling off from the surface of the zinc negative electrode, reducing the capacity of the battery.

[0004] Therefore, in order to improve the reversibility of the battery, researchers have proposed many methods to inhibit dendrite growth, hydrogen evolution and corrosion, etc. to obtain more stable and efficient zinc negative electrode, mainly including interface modification, structure design and electrolyte modification methods, but the above methods still have the problems of relatively complex process and difficult process uniformity control. Therefore, dendrite growth is still a problem that needs to be solved for aqueous zinc ion batteries. SUMMARY

[0005] In view of the deficiencies in the prior art, one of the purposes of the present application is to provide a preparation method of copper-permeated doped zinc metal negative electrode material for zinc ion battery.The preparation method of the present application is simple in process, and the copper atoms are permeated into the zinc metal by heating, so that the surface of the zinc metal changes from smooth to uniform granular structure.The structure makes the zinc ions not easy to concentrate and deposit, avoids the generation of sharp tip effect and the phenomenon of uneven charge deposition, effectively prevents the problem of dendrite piercing the separator, reduces the polarization voltage of the battery, and improves the cycle stability of the battery.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] A preparation method of copper-permeated doped zinc metal negative electrode material for zinc ion battery, comprising the following steps:

[0008] The copper foil and the zinc foil are stacked together, the smooth surface of the copper foil is in contact with the zinc foil, then the copper foil and the zinc foil are rolled into a cylindrical shape and fixed, and calcination is carried out under a protective gas, so that the copper-permeated doped zinc metal negative electrode material is obtained.

[0009] In the present application, the copper atoms are permeated into the zinc metal by heat treatment, the morphology structure of the zinc metal surface is changed, the surface of the zinc metal changes from smooth to uniform granular structure, the local current density is reduced to make the electric field distribution uniform, the metal ion deposition is promoted, the preferential orientation deposition of zinc ions is limited, the dendrite growth is effectively inhibited, and the cycle stability of the zinc ion aqueous battery is improved, and excellent electrochemical performance is exhibited.

[0010] Preferably, the copper foil is on the outside of the cylinder, and the zinc foil is on the inside of the cylinder.

[0011] Preferably, the calcination temperature is 200-400 DEG C, and the calcination time is 3-5h.More preferably, the calcination temperature is 400 DEG C, and the calcination time is 5h.

[0012] Preferably, the calcination conditions are as follows: the temperature is raised to 200-400 DEG C at a temperature rising speed of 2-8 DEG C / min, and then the temperature is kept for 3-5h.

[0013] Preferably, the protective gas is nitrogen, and the protective gas is introduced into the reactor to a pressure of 0.3-0.5MPa.

[0014] Another purpose of the present application is to provide a copper-permeated doped zinc metal negative electrode material prepared by the preparation method, and the surface of the material has a uniform granular structure.

[0015] Preferably, the size of the particles is 30-50nm.

[0016] Still another purpose of the present application is to provide the application of the copper-permeated doped zinc metal negative electrode material prepared by the preparation method in zinc battery.

[0017] Compared with the prior art, the present application has the beneficial effects that:

[0018] (1) The present application makes copper atoms penetrate into the interior of zinc metal by heat treatment, changes the surface of the zinc metal from smooth to uniform granular, promotes uniform deposition of metal ions, thereby limiting the preferential orientation deposition of zinc ions, effectively inhibiting dendrite growth, avoiding the generation of sharp tip effect and the phenomenon of uneven deposition of electric charge, and further improving the cycle stability of the zinc ion aqueous battery, while reducing the polarization voltage of the battery, which can effectively avoid the problem of dendrite piercing the separator.

[0019] (2) Compared with ordinary zinc negative electrode materials, the polarization voltage of the negative electrode material prepared by the present application is lower, the coulombic efficiency is higher, and the cycle performance is better.

[0020] (3) The initial capacity of the zinc ion battery prepared by using the copper-permeated doped zinc metal negative electrode material of the present application reaches 210 mAh / g or more at a current density of 5 A / g, and the capacity can still reach 190 mAh / g or more after 200 cycles, showing high capacity and excellent cycle stability. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The process flow chart for preparing the copper-permeated doped zinc metal negative electrode material of the present application;

[0022] Figure 2 The real object comparison chart of the copper-permeated doped zinc metal negative electrode material of the present application and ordinary zinc foil;

[0023] Figure 3 The XRD chart of the permeated doped zinc metal negative electrode material prepared in Example 1 and ordinary zinc foil, ordinary copper foil;

[0024] Figure 4 The SEM chart of the permeated doped zinc metal negative electrode material prepared in Example 1, Comparative Examples 1 and 2 and ordinary zinc foil;

[0025] Figure 5 The long cycle performance chart of the symmetric battery;

[0026] Figure 6 The coulombic efficiency and single cycle comparison chart of the half battery;

[0027] Figure 7 The (NH4) x Discharge specific capacity chart of (NH4)

[0028] Figure 8 Discharge specific capacity chart of (NH4) xCV cycle diagram of VO3 / / Cu-Zn full cell. Detailed Implementation

[0029] The applicant will now provide a detailed description of the method of the present invention with reference to specific embodiments, in order to enable those skilled in the art to clearly understand the present invention. However, the following embodiments should not be construed in any way as limiting the scope of protection claimed in the present invention.

[0030] Example 1

[0031] like Figure 1 As shown, the preparation method of the copper-doped zinc metal (named Cu-Zn) negative electrode material for zinc-ion batteries in this embodiment includes the following steps:

[0032] S1. First, cut both zinc foil and copper foil into squares with a side length of 9*9 cm. Then, stack the cut squares tightly together and roll them into a cylinder. After rolling, place the copper foil on the outside of the cylinder and the zinc foil on the inside of the cylinder. At the same time, the smooth side of the copper foil is in contact with the zinc foil, and the rough side is facing outward. After assembly, place it in a tube furnace.

[0033] S2. The sample was then calcined. Before calcination, the tube furnace program was set as follows: the starting temperature was room temperature, the heating rate was 8℃ / min, the heating time was 50 min, the maximum temperature was 400℃, the holding time was 300 min, the program was terminated after holding and the cooling began.

[0034] S3. After the program is set up, check the airtightness of the device. The initial nitrogen output rate is 100 mL / min. After a period of time, reduce the output rate to 50 mL / min and control the pressure at 0.50 MPa. Calcinate the sample. After the sample in the tube furnace has been calcined and cooled to room temperature, take out the sample.

[0035] Figure 2 The image shows a comparison between the Cu-Zn anode material prepared in Example 1 and ordinary zinc foil. It can be seen that the surface of the zinc foil changes from silvery-white to light yellow.

[0036] Figure 3 The XRD patterns of the Cu-Zn anode material prepared in Example 1, ordinary zinc foil, and ordinary copper foil are shown. As can be seen from the figure, Zn and Cu are consistent with the standard PDF card, indicating that the sample has high purity. The characteristic peaks of Cu-Zn material are consistent with those of Zn in the figure, indicating that it is based on Zn. The consistency with the characteristic peaks of Cu indicates that Cu atom doping was successful.

[0037] Example 2

[0038] The preparation method of Cu-Zn negative electrode material for zinc-ion batteries in this embodiment includes the following steps:

[0039] S1. First, the zinc foil and copper foil are cut into squares with a side length of 8*8 cm, and then the cut squares are tightly stacked together and made into a cylindrical shape by a winding shaft. After winding, the copper foil is on the outside of the cylinder, and the zinc foil is on the inside of the cylinder. At the same time, the smooth side of the copper foil is in contact with the zinc foil, and the rough side faces outward. After assembly, it is placed in a tube furnace;

[0040] S2. Then the sample is calcined. Before calcination, set the tube furnace program: the initial temperature is room temperature, the heating rate is 5℃ / min, the heating time is 75 min, the highest temperature is 375℃, and the holding time is 240 min. After holding, terminate the program and start cooling;

[0041] S3. After the program is set, check the gas tightness of the device. The initial output rate of nitrogen is 200 mL / min, which is reduced to 60 mL / min after a period of time, and the control pressure is 0.45 MPa. The sample is calcined. After the sample in the tube furnace is calcined and cooled to room temperature, the sample is taken out.

[0042] Example 3

[0043] The preparation method of the Cu-Zn negative material for zinc ion battery in this embodiment includes the following steps:

[0044] S1. First, the zinc foil and copper foil are cut into squares with a side length of 7*7 cm, and then the cut squares are tightly stacked together and made into a cylindrical shape by a winding shaft. After winding, the copper foil is on the outside of the cylinder, and the zinc foil is on the inside of the cylinder. At the same time, the smooth side of the copper foil is in contact with the zinc foil, and the rough side faces outward. After assembly, it is placed in a tube furnace;

[0045] S2. Then the sample is calcined. Before calcination, set the tube furnace program: the initial temperature is room temperature, the heating rate is 4℃ / min, the heating time is 80 min, the highest temperature is 320℃, and the holding time is 240 min. After holding, terminate the program and start cooling;

[0046] S3. After the program is set, check the gas tightness of the device. The initial output rate of nitrogen is 300 mL / min, which is reduced to 70 mL / min after a period of time, and the control pressure is 0.40 MPa. The sample is calcined. After the sample in the tube furnace is calcined and cooled to room temperature, the sample is taken out.

[0047] Example 4

[0048] The preparation method of the Cu-Zn negative material for zinc ion battery in this embodiment includes the following steps:

[0049] S1. First, the zinc foil and copper foil are cut into squares with a side length of 6*6 cm, and then the cut squares are tightly stacked together and made into a cylindrical shape by a winding shaft. After winding, the copper foil is on the outside of the cylinder, and the zinc foil is on the inside of the cylinder. At the same time, the smooth side of the copper foil is in contact with the zinc foil, and the rough side faces outward. After assembly, place it in a tube furnace;

[0050] S2. Then, the sample is subjected to calcination treatment. Before calcination, set the tube furnace program: the initial temperature is room temperature, the heating rate is 3℃ / min, the heating time is 90 min, the highest temperature is 270℃, and the holding time is 210 min. After holding, terminate the program and start cooling;

[0051] S3. After the program is set, check the gas tightness of the device. The initial output rate of nitrogen gas is 400 mL / min, which is reduced to 80 mL / min after a period of time, and the control pressure is 0.50 MPa. The sample is calcined. After the sample in the tube furnace is calcined and cooled to room temperature, the sample is removed.

[0052] Example 5

[0053] The preparation method of the Cu-Zn negative material for zinc ion battery in this embodiment includes the following steps:

[0054] S1. First, the zinc foil and copper foil are cut into squares with a side length of 5*5 cm, and then the cut squares are tightly stacked together and made into a cylindrical shape by a winding shaft. After winding, the copper foil is on the outside of the cylinder, and the zinc foil is on the inside of the cylinder. At the same time, the smooth side of the copper foil is in contact with the zinc foil, and the rough side faces outward. After assembly, place it in a tube furnace;

[0055] S2. Then, the sample is subjected to calcination treatment. Before calcination, set the tube furnace program: the initial temperature is room temperature, the heating rate is 2℃ / min, the heating time is 100 min, the highest temperature is 200℃, and the holding time is 180 min. After holding, terminate the program and start cooling;

[0056] S3. After the program is set, check the gas tightness of the device. The initial output rate of nitrogen gas is 500 mL / min, which is reduced to 90 mL / min after a period of time, and the control pressure is 0.30 MPa. The sample is calcined. After the sample in the tube furnace is calcined and cooled to room temperature, the sample is removed.

[0057] Comparative Example 1

[0058] The preparation method of the Cu-Zn negative material of the present comparative example is basically the same as that of Example 1, and the only difference is that in step S1, the zinc foil and the copper foil are first cut into squares with a side length of 9*9 cm, and then the cut squares are tightly stacked together, with the smooth side of the copper foil in contact with the zinc foil, and then placed in a tube furnace;

[0059] The material obtained in the present comparative example is named Cu-Zn (unrolled).

[0060] Comparative Example 2

[0061] The preparation method of the Cu-Zn negative material of the present comparative example is basically the same as that of Example 1, and the only difference is that in step S1, the rough side of the copper foil is in contact with the zinc foil.

[0062] The material obtained in the present comparative example is named Cu-Zn (rough side).

[0063] The SEM images of the Cu-Zn prepared in Example 1, the Cu-Zn (unrolled) prepared in Comparative Example 1, the Cu-Zn (rough side) prepared in Comparative Example 2, and the ordinary zinc foil are shown in FIGS. 1a-1h. Figure 4 As can be seen from the figures, the surface of the material prepared in Example 1 has a clear granular structure; as can be seen from the figures, the surface of the material prepared in Comparative Example 1 has many cracks; as can be seen from the figures, the surface of the material prepared in Comparative Example 2 has a few small particles, but there is no obvious change compared with the ordinary zinc foil; and as can be seen from the figures, the surface of the ordinary zinc foil is smooth. In summary, the specific heat treatment method of the present application can change the smooth surface of zinc metal into a rough surface, and the surface is uniformly granular, which makes the local charge distribution uniform, induces uniform deposition of Zn 2+ , effectively inhibits the growth of zinc dendrites, and slows down the degradation rate of the electrode.

[0064] Application Example

[0065] ①Long cycle test at 25℃

[0066] The materials prepared in Example 1 and Comparative Examples 1-2 and the ordinary zinc foil were respectively assembled into symmetrical batteries, and the assembled symmetrical batteries were tested on a blue electricity test system. The symmetrical battery test conditions were as follows: the electrolyte was 2 mol / L ZnSO4•7H2O, two pieces of each of the materials prepared in Example 1 and Comparative Examples 1-2 and the ordinary zinc foil were cut into circular pieces with a diameter of 12 mm, and were assembled into symmetrical batteries as positive and negative electrodes. The symmetrical batteries were tested at a current density of 5 mA cm -2Current density constant current charge / discharge, charge / discharge step time is 0.2 h, and the test battery is placed for 30 s after each step is completed. The cycle stability of the battery is tested.

[0067] The test results are shown in Figure 5 , from Figure 5 (a) it can be seen that the Cu-Zn / / Cu-Zn symmetric battery prepared from the material of example 1 exhibits more stable cycle performance and smaller polarization voltage at a current density of 5 mA cm -2 . And from the local cycle Figure 5 (b) and (c), it can be seen that the Cu-Zn / / Cu-Zn symmetric battery has more stable and smaller polarization voltage than the other three, and always maintains a stable overpotential of 40 mV, showing stable long cycle performance. It shows that it can promote the uniform deposition of Zn 2+ and inhibit the growth of zinc dendrites, so that the cycle stability is obviously improved.

[0068] 2. Coulomb efficiency test at 25°C

[0069] The Cu-Zn prepared in example 1 was cut into a circular piece with a diameter of 12 mm as the negative electrode, and a 12 mm Cu foil was used as the positive electrode to assemble a Cu-Zn / / Cu half battery; the Cu-Zn (not rolled) prepared in comparative example 1 was cut into a circular piece with a diameter of 12 mm as the negative electrode, and a 12 mm Cu foil was used as the positive electrode to assemble a Cu-Zn / / Cu half battery (not rolled); the Cu-Zn (rough surface) prepared in comparative example 2 was cut into a circular piece with a diameter of 12 mm as the negative electrode, and a 12 mm Cu foil was used as the positive electrode to assemble a Cu-Zn / / Cu half battery (rough surface); a common Zn foil was cut into a circular piece with a diameter of 12 mm as the negative electrode, and a 12 mm Cu foil was used as the positive electrode to assemble a common Zn / / Cu half battery; the assembled half battery was tested on a blue electricity test system. The half battery test conditions are: the electrolyte is 2 mol / L ZnSO4·7H2O, and the current density is 5 mA cm -2 Constant current discharge, discharge step time is 0.2 h, and the charging cutoff voltage is 1 V. The test battery is placed for 30 s after each step is completed. The Coulomb efficiency of the battery is tested.

[0070] The test results are shown in Figure 6 , from Figure 6 (a) it can be seen that the battery assembled by applying the Cu-Zn of example 1 has more stable Coulomb efficiency than the other three batteries after 250 cycles, and the Coulomb efficiency is always maintained above 95%. From Figure 6 (b) (c) (d) (e), in the single cycle comparison of the 3rd, 50th, 100th cycle, Cu-Zn has smaller polarization voltage, only 57 mV, and the cycle stability is obviously improved.

[0071] ③ Perform cyclic stability testing at 25℃

[0072] The positive electrode was prepared as follows: ammonium vanadate (positive active material), acetylene black (conductive agent), and polyvinylidene fluoride (binder) were mixed in a weight ratio of 7:2:1. N-methylpyrrolidone (N-methylpyrrolidone) was added as a solvent, and the mixture was thoroughly stirred to form a uniform positive electrode slurry. This slurry was coated onto a carbon paper substrate and then dried to obtain the positive electrode. The carbon paper thickness was 20 μm, and the active material layer on the substrate had a thickness of 30 μm. Cu-Zn from Example 1 and ordinary Zn foil were used as negative electrodes in the assembly of a full cell. The assembled battery was tested on a Blue Electric testing system. The full cell test conditions were: 2 mol / L ZnSO4•7H2O as the electrolyte; 15 mm Cu-Zn and ordinary Zn foil discs were used as negative electrodes; and a 12 mm positive electrode was used as the positive electrode. Constant current charging / discharging was performed at a current density of 5 A / g, with the charge / discharge range set to 0.4–1.8 V, to test the cycle stability of the battery.

[0073] Test results are as follows Figure 7 As shown, from Figure 7 (a) It can be seen that at a current density of 5 A / g, (NH4) x The VO3 / / Cu-Zn full cell achieves an initial capacity of over 210 mAh / g, and after 200 cycles, its capacity still exceeds 190 mAh / g, demonstrating high capacity and excellent cycle stability. Figure 7 As shown in (b) and (c), the capacity curves indicate that (where the positive slope curve is the charging curve, which shows the trend of charging capacity with voltage change, indicating the charging platform; and the negative slope curve is the discharging curve, which shows the trend of discharging capacity decreasing with voltage change, reflecting the discharging platform), in the battery system with Cu-Zn as the negative electrode, the polarization voltage is smaller and the capacity platform is flatter, the curve fit is higher, and the stable voltage curve platform as a whole reflects the good compatibility of the positive and negative electrodes and the separator. On the obvious charging and discharging platforms of both, the specific capacity of Cu-Zn full cells with the same number of cycles is better than that of ordinary Zn full cells. This shows that Cu-Zn as the negative electrode of the present invention can significantly improve the long-cycle stability of zinc-ion batteries.

[0074] ④ Cyclic voltammetry (CV) performance was tested under constant temperature conditions of 25℃.

[0075] The full battery assembled with Cu-Zn of application example 1 as negative electrode was subjected to cyclic CV test, test conditions were: ChI660E type electrochemical workstation, voltage range of 0.4~1.4V and scanning speed of 1 mV / s, electrolyte was 2 mol / L of ZnSO4·7H2O, and the round sheet of 15 mm Cu-Zn and common Zn foil was used as negative electrode, and the positive electrode sheet of 12 mm was used as positive electrode.

[0076] The test results are shown in Figure 8 Figure 8 It can be seen that the potential of oxidation peak is about 1.18 V, which corresponds to the oxidation process of VO3 - ; the potential of reduction peak is about 0.872 V, which corresponds to the reduction process of VO3 - ; the measured results show that the peak shape is symmetrical and sharp, indicating that the electrode has good reversibility.

[0077] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.​

Claims

1. A method for preparing a copper-doped zinc metal anode material for zinc-ion batteries, characterized in that, Includes the following steps: Copper foil and zinc foil are stacked together, with the smooth surface of the copper foil in contact with the zinc foil. They are then rolled into a cylindrical shape and fixed, and calcined under a protective gas to obtain the copper-doped zinc metal anode material.

2. The preparation method according to claim 1, characterized in that, The copper foil is on the outside of the cylinder, and the zinc foil is on the inside of the cylinder.

3. The preparation method according to claim 1, characterized in that, The calcination temperature is 200~400℃, and the calcination time is 3~5h.

4. The preparation method according to claim 3, characterized in that, The calcination temperature is 400℃, and the calcination time is 5 hours.

5. The preparation method according to claim 1, characterized in that, The calcination conditions are as follows: the temperature is increased to 200-400℃ at a heating rate of 2-8℃ / min, and then held at that temperature for 3-5 hours.

6. The preparation method according to claim 1, characterized in that, The protective gas is nitrogen or argon, and the pressure inside the reactor is 0.3~0.5 MPa.

7. The copper-doped zinc metal anode material prepared by the preparation method according to any one of claims 1 to 6, characterized in that, The surface of the material has a uniformly distributed granular structure.

8. The copper-doped zinc metal anode material according to claim 7, characterized in that, The size of the particles is 30~50nm.

9. The application of the copper-doped zinc metal anode material prepared by the preparation method according to any one of claims 1 to 6 or the copper-doped zinc metal anode material according to claim 8 in zinc batteries.

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