Modified zinc negative electrode, preparation thereof and application of modified zinc negative electrode in aqueous zinc battery

Abstract

The invention belongs to the field of aqueous zinc batteries, and particularly relates to a modified zinc negative electrode and preparation and application thereof.The modified zinc negative electrode comprises a zinc substrate and a modified layer compounded on the surface of the zinc substrate, the modified layer comprises a binder and a modified material, and the modified material comprises MZrOx and zeolite according to the weight ratio of 0.5-1.5: 1; m in MZrOx is one or more of Zn, Mg, Ni, Sr, Si, Fe, Cr, Ba and Al, and the molar ratio of M to Zr is (3-15): 50. According to the invention, the modified layer containing MZrOx and zeolite is innovatively formed on the zinc negative electrode, and the MZrOx proportion and the combined control of the components in the modified material are matched, so that the synergism can be realized, the physical and chemical characteristics of the aqueous zinc battery can be accidentally adapted, the core problem of hydrogen evolution and gas production in the aqueous zinc battery system is solved, and the service life of the aqueous zinc battery is prolonged. The problems of self-corrosion, gas production and the like of the zinc negative electrode in aqueous electrolyte can be effectively solved, and the stability and the cycle life of the aqueous zinc ion battery are remarkably improved and prolonged.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more specifically to the field of aqueous zinc-ion battery technology. Background Technology

[0002] Among secondary batteries, compared with the disadvantages of lithium-ion batteries such as high manufacturing cost, low safety, environmental pollution and resource limitations, aqueous batteries have received much attention in recent years due to their advantages such as being green and environmentally friendly, low cost, good safety and good rate performance. They have been extensively studied in lithium-ion batteries, sodium-ion batteries and zinc-ion batteries.

[0003] Zinc metal possesses high conductivity, ease of processing, high stability and safety in water, low toxicity, and low cost. Furthermore, zinc anodes are abundant in nature, possess a high theoretical capacity (820 mAh / g) and a suitable redox potential (-0.76 V), and exhibit relatively low polarizability compared to other metallic materials (such as Mg and Al). However, zinc anodes currently face problems such as dendrite formation, passivation, and hydrogen evolution reaction (HER), which severely restrict the practical application of aqueous zinc-ion batteries. The HER occurs when active H₂O molecules adsorbed on the Zn electrode surface under low potential conditions undergo hydrolysis to produce hydrogen. + At the same time, the ionization of water produces H+. + OH - OH - With Zn 2+ Complexation, leading to H + With increasing concentration, the electrolyte pH is <7. Due to the lack of a protective layer, a displacement reaction occurs on the zinc anode surface, H... + It gains electrons to generate H2 (2H) + + 2e - H₂↑ is a strong competing reaction for the reduction of active Zn. This not only significantly reduces the coulombic efficiency of aqueous zinc-ion batteries, but also causes gas accumulation leading to battery swelling, posing a safety risk. Meanwhile, OH⁻… - The formation of [a substance] further promotes zinc corrosion (Zn + 4OH-). - → Zn(OH)4 2- + 2e - → ZnO + 2OH -The hydrogen evolution reaction (H2O) gradually passivates the negative electrode surface, hindering mass transfer at the zinc negative electrode / electrolyte interface, causing surface inhomogeneity, accelerating uneven zinc deposition, and further accelerating dendrite growth, resulting in a shortened lifespan of aqueous zinc-ion batteries. Therefore, studying the suppression of the hydrogen evolution reaction is of great significance for improving the performance of aqueous zinc-ion batteries. It is evident that effectively suppressing the hydrogen evolution reaction through the synergistic effect of surface chemistry and electrochemistry, and improving the uniform deposition of zinc ions on the surface, can enhance battery stability and cycle life, which is of great significance for the development of large-scale energy storage devices.

[0004] Therefore, in order to address the above problems, finding a way to protect the zinc anode and developing a protective coating that can effectively inhibit hydrogen evolution corrosion of the zinc anode is crucial for improving the capacity and service life of aqueous zinc-ion batteries. Summary of the Invention

[0005] To address the problem that zinc anodes are prone to self-corrosion and gas generation, resulting in unsatisfactory electrochemical performance, the primary objective of this invention is to provide a modified zinc anode that can effectively suppress self-corrosion and gas generation and has excellent stability.

[0006] The second objective of this invention is to provide a method for preparing the modified zinc anode and its application in aqueous zinc-ion batteries.

[0007] A third objective of this invention is to provide an aqueous zinc-ion battery comprising the modified zinc anode.

[0008] A modified zinc anode includes a zinc substrate and a modified layer composited thereon. The modified layer includes a binder and a modifying material, wherein the modifying material comprises MZrO in a weight ratio of 0.5 to 1.5:1. x And zeolite, M is one or more elements selected from Zn, Mg, Ni, Sr, Si, Fe, Cr, Ba and Al; MZrO x In this process, the molar ratio of M to Zr is 3 to 15:50.

[0009] This invention innovatively forms a zinc anode containing MZrO x Modified layer of zeolite, combined with MZrO x By controlling the proportions and components in the modified materials, a synergistic effect can be achieved, which can unexpectedly adapt to the physicochemical characteristics of aqueous zinc batteries, solve the core problem of hydrogen evolution and gas production in aqueous zinc battery systems, effectively solve the problems of self-corrosion and gas production of zinc anodes in aqueous electrolytes, and significantly improve the stability and cycle life of aqueous zinc-ion batteries.

[0010] In this invention, the zinc substrate is zinc foil, zinc alloy foil, or 3D zinc.

[0011] In this invention, MZrOx Also known as a modifier, it is a solid solution of oxides of metals M and Zr. The x value is affected by the type of M and the ratio of M to Zr, and can be reasonably calculated based on the M / Zr ratio and chemical valence equilibrium.

[0012] As an optional solution, MZrO x In this context, M can be Zn. Studies have shown that using a Zn / Zr composite oxide solid solution, along with the synergistic control of the ratio of the two components and the proportion of the modified material, can further enhance the hydrogen evolution problem of the electrode and improve its stability.

[0013] In this invention, the MZrO x The preparation steps are as follows: co-precipitate water-soluble M source and water-soluble Zr source, and then perform oxidative calcination treatment to obtain the product.

[0014] The MZrO of this invention x The preparation method can be adapted to the application requirements of aqueous zinc batteries and can improve the hydrogen production problem in aqueous zinc batteries.

[0015] In this invention, the water-soluble M source and the water-soluble Zr source are respectively the nitrates and organic acid salts of their respective metals.

[0016] In this invention, the M / Zr molar ratio is 3~15:50, more preferably 5~10:50; and even more preferably 6~8:50. Studies have shown that the preferred ratio helps to further enhance the synergistic effect of the components of this invention and helps to further strengthen the stability of the aqueous zinc electrode.

[0017] Preferably, the precipitant in the co-precipitation process is at least one of a hydroxide precipitant and a carbonate precipitant.

[0018] In this invention, the oxidative roasting process is carried out in an oxygen-containing atmosphere, such as air or a mixture of oxygen and dilution gas. The dilution gas is, for example, at least one of nitrogen or a rare gas.

[0019] Preferably, the temperature of the oxidative roasting process is 350~850℃, and more preferably 450~550℃.

[0020] Preferably, the oxidative calcination time is 1 h to 10 h; more preferably, it can be 2 h to 5 h.

[0021] In this invention, the zeolite is preferably mordenite.

[0022] MZrO x The weight ratio of zinc to zeolite is 0.9~1.1:1. At this preferred ratio, the hydrogen production problem faced by aqueous zinc batteries can be further addressed, resulting in better stability.

[0023] In this invention, the binder in the modified layer includes at least one of PVDF, PAA, and PI.

[0024] In this invention, the content of the modified material in the modified layer can be 5~20 wt.%, and more preferably 10~15 wt.%.

[0025] In this invention, the thickness of the modified layer is 5~50 μm, for example, it can be 20~25 μm.

[0026] This invention also provides a method for preparing the modified zinc anode, wherein MZrO x Zeolite and binder are slurried with solvent, then coated onto a zinc substrate and dried to obtain the modified zinc anode.

[0027] In this invention, after coating, the dried electrode is treated with an alcohol-water mixed solvent to obtain the modified zinc anode. This modification treatment further enhances the hydrogen evolution resistance of the prepared modified electrode in aqueous batteries, contributing to improved stability.

[0028] In this invention, the alcohol in the alcohol-water mixed solvent can be methanol, ethanol, or other components. The volume ratio of alcohol to water in the alcohol-water mixed solvent is 1:0.5~2.

[0029] This invention also provides an application of the modified zinc anode, which is used as a negative electrode in the preparation of aqueous zinc-ion batteries; wherein the modified zinc anode is the modified zinc anode described in this invention.

[0030] The present invention also provides an aqueous zinc-ion battery, comprising a battery cell and an aqueous electrolyte for soaking the battery cell, wherein the battery cell comprises a negative electrode, a separator and a positive electrode sequentially combined, and the negative electrode is the modified zinc negative electrode of the present invention.

[0031] As an optional solution, the aqueous zinc-ion battery can be an aqueous zinc-manganese battery, a zinc-vanadium battery, etc.

[0032] Beneficial effects

[0033] This invention innovatively forms a zinc anode containing MZrO x (Also known as MZr bimetallic oxide solid solution) and zeolite modification layer, combined with MZrO x The M / Zr ratio and MZrO xBy controlling the weight ratio of zinc to zeolite, a synergistic effect can be achieved, which can unexpectedly adapt to the physicochemical characteristics of aqueous zinc batteries. This can solve the core problem of hydrogen evolution and gas production in aqueous zinc battery systems, effectively solve the problems of self-corrosion and gas production of zinc anode in aqueous electrolyte, and significantly improve the stability and cycle life of aqueous zinc-ion batteries. Attached Figure Description

[0034] Figure 1 ZnZrO prepared in Example 1 x X-ray diffraction (XRD) pattern of the material;

[0035] Figure 2 ZnZrO prepared in Example 1 x / Scanning electron microscope (SEM) image of mordenite zeolite material;

[0036] Figure 3 Cyclic curves of symmetrical cells assembled with zinc electrode sheets in Example 1 and Comparative Example 1;

[0037] Figure 4 Linear current-voltage scan (LSV) curves of the symmetrical cells assembled with zinc electrode sheets in Example 1 and Comparative Example 1;

[0038] Figure 5 Tafel curves for the symmetrical cells assembled with zinc electrode sheets in Example 1 and Comparative Example 1;

[0039] Figure 6 Cyclic voltammetry (CV) curves of the full cells with zinc anode and manganese dioxide cathode matched in Example 1 and Comparative Example 1;

[0040] Figure 7 The full-cell charge-discharge cycle curves and cycle efficiency curves of the zinc negative electrode and manganese dioxide positive electrode matched in Example 1 and Comparative Example 1 are shown. Detailed Implementation

[0041] The following description, in conjunction with embodiments of the present invention, further illustrates the function and application of the invention, providing a clear and complete description of the technical solutions in the embodiments. It is worth noting that the following embodiments are only some embodiments of the present invention, intended to aid in understanding the invention, and not all of them, and should not be considered as limitations on the implementation of the invention.

[0042] Example 1

[0043] This embodiment provides ZnZrO x / Modified ZnZrO in Zn anode by mordenite zeolite catalyst x Synthesis method of mordenite zeolite catalyst and ZnZrO x Methods for fabricating symmetric cells and full cells using mordenite@Zn.

[0044] Step 1: ZnZrO x Synthesis (also known as ZnZr oxide solid solution)

[0045] Step 1.1: Cut the pure zinc sheet electrode material into electrode discs with a diameter of 1.2 cm. Immerse the electrode discs in anhydrous ethanol for ultrasonic cleaning for 10 min. After cleaning, place them in a vacuum drying oven for drying to obtain pure Zn electrode discs (also known as Bare Zn in this invention).

[0046] Step 1.2: Dissolve zirconium nitrate pentahydrate and zinc nitrate hexahydrate with a Zr / Zn molar ratio of 27:4 in deionized water to obtain a metal salt solution.

[0047] Step 1.3: Dissolve ammonium carbonate in an aqueous solution to obtain an ammonium carbonate aqueous solution.

[0048] Step 1.4: Slowly add the ammonium carbonate aqueous solution dropwise into the metal salt solution at a constant temperature of 70°C to carry out the reaction. The amount of ammonium carbonate used is 1.2 to 1.5 times the theoretical amount of zirconium and zinc to be precipitated.

[0049] Step 1.5: After the addition is complete, continue stirring and aging at 70°C for 2 hours.

[0050] Step 1.6: Cool the aged solution to room temperature, then filter, wash with water, and dry to obtain the ZnZr precursor.

[0051] Step 1.7: Calcine the ZnZr precursor in air at 500℃ for 3 hours to obtain the final ZnZr oxide solid solution (ZnZrO). x product).

[0052] Figure 1 ZnZrO after high-temperature calcination in a Marfé furnace x The XRD characterization spectrum of the sample showed a good match between the diffraction peaks and the characterization spectrum (JCPDS No. 32-1482), confirming that ZnZrO x Successful synthesis.

[0053] Step 2: ZnZrO x Method for fabricating a mordenite-Zn countercell:

[0054] The final product ZnZrO x Mordant zeolite molecular sieves were added and mixed at a weight ratio of 1:1, then ground to obtain the modified material. SEM images are shown below. Figure 2 As can be seen from the figure, ZnZrO x The nanoparticles of the material are uniformly dispersed on the mordenite zeolite, reflecting the ZnZrO x The uniform distribution.

[0055] The modified material was added to an appropriate amount of PVDF (PVDF to modified material weight ratio of 1:9) / NMP solution (solvent) and stirred for about 5 hours to form a slurry. The resulting ZnZrO was then further processed. x A mordenite zeolite composite slurry is uniformly coated onto a pure Zn electrode disc (spin coating method), and then dried in a vacuum drying oven at 100℃ for 4 h to obtain ZnZrO. x / Silky zeolite@Zn electrode sheet (the thickness of the modified layer is 23μm).

[0056] Test 1: Half-battery test:

[0057] ZnZrO x The mordenite-Zn electrode sheet serves as the two electrodes, which are then assembled with a diaphragm (glass fiber membrane) and a 3M ZnSO4 solution as the electrolyte to form ZnZrO. x / Silicone zeolite@Zn symmetric cell. After the assembled cell was left to stand for 5 hours, electrochemical performance tests such as cycle performance, LSV, and Tefal were performed.

[0058] Test 2: Full Battery Test

[0059] ZnZrO x Method for making a mordenite zeolite full cell:

[0060] Negative electrode: ZnZrO x / Silky zeolite@Zn anode (same as step 2);

[0061] Electrolyte: 2M ZnSO4 + 0.2M MnSO4 solution;

[0062] The diaphragm is a glass fiber membrane.

[0063] Positive electrode: Manganese dioxide, PVDF, and conductive carbon black in a weight ratio of 7:2:1 were used as the positive electrode materials. The NMF was slurry-coated onto Ti foil and dried in a vacuum drying oven at 70°C for 12 hours. The dried material served as the positive electrode.

[0064] A battery cell is formed by combining a positive electrode, a separator, and a negative electrode. The battery cell is then immersed in an electrolyte to assemble a full battery, which is then subjected to CV, rate, and constant current charge-discharge tests.

[0065] Example 2

[0066] Compared with Example 1, the only difference is that the ZnZrO in step 1 is changed. x The Zn / Zr molar ratios during the synthesis process were 3:50, 5:50, and 13:50, respectively. All other test conditions were the same as in Example 1.

[0067]

[0068] In this case, the cycle life of a symmetrical battery refers to the battery's lifespan during a short circuit.

[0069] A cycle life of more than a certain time means that there has been no short circuit by the time the cycle reaches that time.

[0070] Example 3

[0071] Compared to Example 1, the only difference is that in step 2, the ZnZrO in the modified material... x The weight ratios of the mordenite zeolite were 0.5:1, 1:1, 2:1, and 3:1, respectively. The total amount of modified material and other operations and parameters were the same as in Example 1.

[0072]

[0073] Example 4

[0074] Compared with Example 1, the only difference is that the electrode after drying in step 2 was immersed in a 1:1 ethanol-water mixture for surface modification for 2 hours, and then dried. All other test conditions were the same as in Example 1.

[0075] At a current density of 2 mA cm -2 The surface capacity is 1mAh cm -2 Under these conditions, the modified zinc anode symmetrical battery exhibited a cycle life of 1440 h without short circuit. The preferred embodiment of Example 4 can achieve cycle stability comparable to Example 1 at even higher current densities, demonstrating superior stability.

[0076] Example 5

[0077] Compared to Example 1, the only difference is that the Zn source in the ZnZrOx synthesis process in step one is changed, and it is replaced with a Mg source to synthesize MgZrOx. Specifically, the zinc nitrate hexahydrate that provides the Zn source is replaced with magnesium nitrate hexahydrate that provides the Mg source. All other steps remain unchanged, and the remaining test conditions are the same as in Example 1.

[0078]

[0079] Example 6

[0080] Compared with Example 1, the only difference is that the temperature in step 1.7 is 450°C and the time is 4 hours; in step 2, the weight ratio of modifier to PVDF is 1.5:8.5, and other operations and parameters are the same as in Example 1.

[0081] At a current density of 1 mA cm -2 The surface capacity is 0.5mAh cm -2 Under the specified conditions, the cycle life of the modified zinc anode symmetric battery was measured to be 1152 h.

[0082] Comparative Example 1

[0083] Compared to Example 1, the only difference is that the negative electrode of the symmetrical cell and the full cell is a pure Zn electrode disc without a composite modification layer (that is, the pure Zn electrode disc after cleaning and drying in step 1.1 of Example 1, also known as Bare Zn). All other test conditions are the same as in Example 1.

[0084] Figure 3 The graphs show the cycle curves of the symmetrical cells assembled with zinc electrode sheets in Example 1 and Comparative Example 1, with a current density of 1 mA cm⁻¹. -2 The surface capacity is 0.5 mAh cm -2 Under the tested conditions, it can be seen from the figure that the bare zinc battery experienced a short circuit after 100 hours of cycling; while ZnZrO x Mordant zeolite can be stably cycled for over 1200 hours. Compared with the conventional anode material preparation method in Comparative Example 1, the aqueous zinc-ion battery anode material prepared in Example 1 of this invention inhibits the hydrogen evolution reaction by adsorbing H, resulting in a uniform distribution of active sites and effectively solving the problem of short battery life caused by uneven zinc ion deposition.

[0085] Figure 4 The linear current-voltage scan (LSV) curves of the symmetric cells assembled in Example 1 and Comparative Example 1 are shown, mainly used to verify ZnZrO. x The inhibitory effect of the mordenite protective layer on the hydrogen evolution reaction, from Figure 5 Analysis shows that when they are at the same voltage, ZnZrO x The mordenite-Zn symmetric cell exhibits a lower response current compared to the bare Zn symmetric cell. Furthermore, compared to bare zinc, ZnZrO... x The mordenite@Zn anode exhibits a low hydrogen evolution potential, which reflects the effect of ZnZrO4 treatment. x The use of mordenite as a coating on the surface of a zinc anode inhibits the hydrogen evolution reaction.

[0086] Figure 5 These are Tafel curves for the symmetrical cells assembled in Example 1 and Comparative Example 1. They are primarily used to quantify the reaction kinetics of the cells. From... Figure 6 As can be seen from this, compared with bare zinc, ZnZrO x The corrosion potential of mordenite@Zn shifts to the right, indicating that the electrolyte has a positive effect on the corrosion of ZnZrO. x The low corrosion tendency of mordenite@Zn reflects the characteristics of ZnZrO. x / Inhibition of corrosion reaction by mordenite zeolite materials.

[0087] Figure 6 The figures show the cyclic voltammetry (CV, scan rate 0.5 mV / s) curves of the full cells assembled in Example 1 and Comparative Example 1. As can be seen from the figures, the two CV curves have basically similar shapes, both showing obvious oxidation and reduction peaks, and ZnZrO... x The closed area of ​​the CV curve for mordenite@Zn is increased compared to that of bare zinc, indicating that ZnZrO x The increased specific capacity of mordenite@Zn promotes reaction kinetics.

[0088] Figure 7 The charge-discharge cycle curves and cycle efficiency curves of the full cells in Example 1 and Comparative Example 1 were obtained by charging and discharging the full cells at 0.1 A g. -1 Long-term cycling performance tests were conducted at a current density of [value missing]. It can be seen that in the first 20 cycles, ZnZrO [performance missing]. x The first discharge capacity of the / mordenite@Zn full battery is 232 mAh g. -1 The highest specific capacity is 250 mAh g. -1 Its specific capacity is much higher than that of Bare Zn, indicating that ZnZrO x / Silky zeolite@Zn gives the full cell faster reaction kinetics, enabling it to have higher capacity.

[0089] Comparative Example 2

[0090] Compared with Example 1, the only difference is that no modified material was added in step 2, while all other test conditions were the same as in Example 1.

[0091] Comparative Example 3

[0092] Compared with Example 1, the only difference is that in step 2, the modified material is only ZnZrO. x The amount of modified material and other test conditions were the same as in Example 1.

[0093] Comparative Example 4

[0094] Compared with Example 1, the only difference is that in step 2, the modified material is only mordenite, and the amount of modified material and other test conditions are the same as in Example 1.

[0095] Comparative Example 5

[0096] Compared with Example 1, the only difference is that in step 2, the mordenite in the modified material is replaced with an equal weight of NaY molecular sieve support, and all other test conditions are the same as in Example 1.

[0097] Table 2 shows the symmetrical cells in Example 1 and Comparative Examples 1, 2, 3, 4, and 5 at a current density of 1 mA cm⁻¹. -2 The surface capacity is 0.5 mAh cm-2 The cycle life is below.

[0098]

[0099] This invention innovatively forms a zinc anode containing MZrO x The modified layer of (also known as MZr bimetallic oxide solid solution) and zeolite can unexpectedly adapt to the physicochemical characteristics of aqueous zinc batteries, solve the core problem of hydrogen evolution and gas production in aqueous zinc battery systems, effectively solve the problems of self-corrosion and gas production of zinc anode in aqueous electrolyte, and significantly improve the stability and cycle life of aqueous zinc-ion batteries.

Claims

1. A modified zinc negative electrode, characterized by, A zinc base and a modified layer compounded on the surface of the zinc base, the modified layer comprising a binder and a modified material, the modified material comprising MZrO x and a zeolite; MZrO x wherein M is one or more of Zn, Mg, Ni, Sr, Si, Fe, Cr, Ba and Al, and the molar ratio of M:Zr is 3-15:

50.

2. The modified zinc negative electrode of claim 1, wherein, The zinc substrate is a zinc foil, a zinc alloy foil or a 3D zinc.

3. The modified zinc anode of claim 1, wherein, In the modification layer, the zeolite is mordenite; and the binder comprises at least one of PVDF, PAA and PI.

4. The modified zinc anode of claim 3, wherein, In the modification layer, the content of the modification material is 5-20 wt.%. Preferably, the thickness of the modification layer is 5-50 μm.

5. A method for producing the modified zinc negative electrode according to any one of claims 1 to 4, characterized by, The MZrO x , zeolite, solvent for binder are slurried and then coated on a zinc substrate, dried to produce the modified zinc negative electrode.

6. The method for producing a modified zinc negative electrode according to claim 5, wherein The MZrO x The preparation steps are: co-precipitation treatment of water-soluble M source and water-soluble Zr source, and then oxidation roasting treatment. Preferably, the precipitant in the co-precipitation process is at least one of a hydroxide precipitant and a carbonate precipitant. Preferably, the temperature of the oxidation roasting process is 350-850℃. Preferably, the time of the oxidation roasting is 1 h-10 h.

7. The method of producing a modified zinc negative electrode according to claim 5, wherein Pre-mixing MZrO x zeolite ball-milling, followed by mixing with a binder slurry, wherein the solvent in the slurry process includes at least one of DMF, NMP, water, ethanol, DMAc.

8. The method for producing a modified zinc negative electrode according to claim 7, wherein After the coating is completed, drying treatment is performed to obtain the modified zinc negative electrode. Alternatively, after the coating is completed, the modified zinc negative electrode is placed in an alcohol-water mixed solvent for surface modification, and then dried.

9. Use of a modified zinc negative electrode, characterized in that The modified zinc negative electrode is used as a negative electrode to prepare a water-based zinc ion battery.

10. An aqueous zinc-ion battery comprising an electric core and an aqueous electrolyte soaking the electric core, wherein, The cell comprises a negative electrode, a separator and a positive electrode which are sequentially compounded, and is characterized in that the negative electrode is the modified zinc negative electrode according to any one of claims 1-4 or prepared by the preparation method according to any one of claims 5-8.

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