Method for manufacturing zinc negative electrode of zinc-ion secondary battery and zinc-ion secondary battery

Abstract

The present invention relates to a method for manufacturing a zinc negative electrode of a zinc-ion secondary battery and a zinc-ion secondary battery, the method comprising: a step of forming an artificial coating layer on the surface of a zinc negative electrode by a chemical reaction performed by immersing zinc metal in an inorganic metal salt solution; and a washing and drying step. The present invention can provide a negative electrode of an aqueous zinc-ion secondary battery, which is a safe and eco-friendly next-generation battery for an electric vehicle and an ESS, and a method for manufacturing same.

Description

Method for manufacturing a zinc negative electrode for a zinc-ion secondary battery and a zinc-ion secondary battery

[0001] The present invention relates to a method for manufacturing a zinc negative electrode of a zinc ion secondary battery including an aqueous electrolyte, and a zinc negative electrode and a zinc ion secondary battery manufactured therefrom.

[0002] As safety concerns surrounding lithium-ion batteries for energy storage systems (ESS) continue to mount, the need for developing aqueous secondary batteries is gaining increasing recognition. Development of a zinc-based aqueous secondary battery utilizing zinc metal, which is fire-safe, inexpensive, and boasts a high theoretical capacity (820 mAh / g), is underway.

[0003] Zinc has been studied as a cathode for aqueous secondary batteries due to its inherent chemical stability in water and low cost. However, zinc is thermodynamically unstable in weakly acidic electrolytes, causing persistent corrosion reactions that accelerate battery deterioration.

[0004] Specifically, the main corrosion reaction of the zinc metal cathode is the hydrogen evolution reaction at the interface between zinc and the electrolyte, which causes a local pH change, resulting in the formation of a non-conductive ZHS (zinc hydroxide sulfate, ZnSO4[Zn(OH)2]3·nH2O) by-product on the surface of the zinc metal cathode, which can be a factor in increasing the charge transfer resistance and accelerating the needle-like growth of zinc.

[0005] Moreover, hydrogen gas generated by the hydrogen evolution reaction (HER) blocks electrochemically active sites on the cathode surface, increasing resistance and accelerating battery deterioration. Furthermore, the needle-like growth of zinc can penetrate the separator, causing internal micro-shorts.

[0006] Therefore, it is necessary to develop a technology that can suppress this phenomenon and improve the stability of zinc-ion batteries by introducing a coating layer on the zinc surface that can suppress the needle-like growth of zinc and side reactions such as HER by uniformly distributing electrons and ions at the zinc metal cathode interface.

[0007] The present invention aims to provide a negative electrode of a safe and environmentally friendly next-generation aqueous zinc-ion secondary battery and a method for manufacturing the same.

[0008] In addition, the purpose of the present invention is to provide an aqueous zinc secondary battery having excellent stability and performance by improving electrochemical zinc deposition / desorption reactivity with excellent overvoltage improvement.

[0009] In order to achieve the above object, the present invention provides a method for manufacturing a zinc anode of a zinc ion secondary battery, comprising the steps of immersing zinc metal in an inorganic metal salt solution to form an artificial film layer on the surface of a zinc anode through a chemical reaction; and the steps of washing and drying.

[0010] Preferably, the inorganic metal salt solution is Ca(OH)2, Mg(OH)2, Ba(OH)2, Al(OH) 3, La(OH) 3, CaCl2, MgCl2, BaCl2, AlCl3, LaCl 3, CaF2, MgF2, BaF2, AlF3, LaF 3, CaCO3, MgCO3, BaCO3, Al2(CO3) 3, La(CO3) 3, CaSO4, MgSO4, BaSO4, and Al2(SO4) 3, A metal precursor comprising at least one selected from the group consisting of La2(SO4)3; and at least one selected from the group consisting of (NH4)F, (NH4)Cl, (NH4)Br, alkylammonium ions, phosphonium and alkylphosphonium ions.

[0011] Preferably, the solvent of the above inorganic metal salt solution is at least one selected from the group consisting of water, alcohol, NMP (N-methyl-2-pyrrolidone), and THF (tetrahydrofuran).

[0012] Preferably, the concentration of the above inorganic metal salt solution is in the range of 1 mM to 5 M.

[0013] Preferably, the immersion time in the step of forming the artificial film layer is in the range of 1 second to 12 hours.

[0014] The present invention provides a zinc negative electrode for a zinc ion secondary battery manufactured by the above method.

[0015] Preferably, the zinc cathode includes an artificial film layer having a thickness of 0.1 to 100 μm on the surface.

[0016] Preferably, the artificial film layer comprises AlF3 and Al2O3, AlCl3 and Al2O3, AlBr3 and Al2O3, It is a composite nano-compound comprising at least one selected from the group consisting of MgF2 and MgO, CaF2 and CaO, BaF2 and BaO, and LaF3 and La2O3.

[0017] Preferably, the zinc cathode is formed by coating a conductive substrate selected from the group consisting of Al foil, Ni foil, Fe foil, titanium foil (Ti foil), titanium foam (Ti foam), carbon nanotube (CNT), carbon nanofiber, carbon fiber, graphene foam, and graphene fiber.

[0018] The present invention provides a zinc ion secondary battery including the zinc negative electrode, positive electrode, separator, and aqueous electrolyte.

[0019] Preferably, the anode comprises at least one selected from the group consisting of MnO2, V2O5, ZnMn2O4, ZnCo2O4, metal vanadates, Br2 / C and I2 / C.

[0020] Preferably, the separator comprises at least one selected from the group consisting of a Nafion-based high-density separator, PI (polyimide), PET (polyethylene terephthalate), cellulose-based separator, ceramic-coated separator, and glass fiber.

[0021] Preferably, the aqueous electrolyte comprises at least one selected from the group consisting of ZnSO4, MnSO4, C2F6O6S2Zn, CoSO4, Mn(CF3SO3)2, ZnBr2, ZnI2, and Na2SO4.

[0022] According to the present invention, the performance of a zinc-ion secondary battery can be improved by forming an artificial film layer of nm to μm scale and suppressing the HER reaction on the surface of a metal zinc anode through strong interaction with water. The present invention enables a continuous coating process of the artificial film using a dissolution coating method, and due to the uniform ion and electron transfer characteristics, it can provide a uniform deposition reaction of zinc metal during charging.

[0023] The present invention enables high stability and excellent performance of a zinc-ion secondary battery including the zinc anode by suppressing high side reactions and uniformity of anode reactions.

[0024] Figure 1 is a schematic diagram showing a method for manufacturing a zinc cathode according to one embodiment of the present invention.

[0025] Figure 2 is a schematic diagram of an artificial film layer, i.e., a composite nano-compound, formed on the surface of a zinc cathode of the present invention.

[0026] Figure 3 is an SEM cross-sectional photograph of a comparative example and an exemplary zinc cathode.

[0027] Figure 4 shows the TOF-SIMS depth analysis results of the comparative and exemplary zinc cathodes.

[0028] Figure 5 is an SEM photograph showing the electrochemical zinc deposition behavior of the comparative and exemplary zinc anodes.

[0029] Figures 6 and 7 show the symmetrical cell cycle characteristics of the comparative and exemplary zinc cathodes.

[0030] Figure 8 shows the performance evaluation results of a zinc ion secondary battery pouch cell.

[0031] The present invention provides a technology for improving the stability of a zinc-ion battery and thereby improving its performance by improving the electrochemical uniformity of a zinc anode of an aqueous zinc-ion battery and suppressing hydrogen generation by water decomposition by coating a zinc anode with a fluorinated metal and a metal oxide.

[0032] That is, by providing an environment that can make the electrochemical reaction characteristics at the interface between the metal zinc anode and the aqueous electrolyte uniform, the present invention provides a zinc anode for an aqueous zinc-ion secondary battery and a method for manufacturing the same, which forms an artificial film layer that can suppress corrosion reaction and HER reaction of the metal zinc and needle-like growth of the zinc metal during charging.

[0033] Figure 1 illustrates a method for manufacturing a zinc cathode according to one embodiment of the present invention and a cathode manufactured therefrom.

[0034] The zinc anode of the present invention is manufactured by immersing zinc metal in an inorganic metal salt solution for a certain period of time, forming an artificial film layer on the surface of the zinc anode through a chemical reaction using a dissolution coating method, and then washing and drying the zinc metal.

[0035] Metal precursors for preparing the above inorganic metal salt solution include metal hydroxide salts such as Ca(OH)2, Mg(OH)2, Ba(OH)2, and Al(OH). 3,La(OH)3, etc., chloride metal salts such as CaCl2, MgCl2, BaCl2, AlCl3, LaCl3, etc., fluoride metal salts such as CaF2, MgF2, BaF2, AlF3, LaF3, etc., carbonate metal salts such as CaCO3, MgCO3, BaCO3, Al2(CO3) 3, La(CO3)3, etc., sulfate metal salts such as CaSO4, MgSO4, BaSO4, Al2(SO4) 3, La2(SO4)3, etc. can be used. In addition, the inorganic metal salt solution contains ammonium cations such as fluorine-based ammonium salts, chloride-based ammonium salts, bromide-based ammonium salts, or alkylammonium ions, phosphonium, alkylphosphonium ions, etc., together with the metal precursor.

[0036] Aqueous solutions are basically used as solvents, and polar organic solvents capable of dissolving salts, such as alcohol, NMP (N-methyl-2-pyrrolidone), and THF (tetrahydrofuran), can be used. The concentration of the inorganic metal salt solution ranges from 1 mM to 5 M.

[0037] Desirable immersion times range from 1 second to 12 hours.

[0038] The cleaning process is not limited to this, but involves several washes using water and ethanol. Drying is for solvent drying, and is performed at temperatures ranging from room temperature to 150°C using methods such as hot air drying.

[0039] The conductive substrate (current collector) may be selected from the group consisting of Al foil, Ni foil, Fe foil, titanium foil, titanium foam, carbon nanotube (CNT), carbon nanofiber, carbon fiber, graphene foam, and graphene fiber.

[0040] In the zinc anode manufacturing method of the present invention, the thickness, shape, and composition of the artificial film layer can be easily controlled by chemically manufacturing the composite nano-compound through a dissolution coating process. Specifically, control is possible depending on the salt concentration, type, immersion time, drying conditions, etc. The composite nano-compound is coated on the zinc metal surface through a chemical precipitation reaction, and its performance is improved through particle complexation. Furthermore, since the anode manufacturing method of the present invention is a dissolution coating process, continuous processing is possible, thus increasing the possibility of commercialization.

[0041] The present invention provides a zinc anode manufactured by the above method.

[0042] The above zinc cathode comprises an artificial film layer having a thickness ranging from 0.1 to 100 μm.

[0043] The above artificial film layer is a metal fluoride or metal oxide-based artificial film layer, specifically AlF3 and Al2O3. AlCl3 and Al2O3, AlBr3 and Al2O3, Examples thereof include, but are not limited to, MgF2 and MgO, CaF2 and CaO, BaF2 and BaO, or LaF3 and La2O3. These exist as complex nano-compounds. That is, in the following examples, AlF3 and Al2O3 are used, which are not compounds of AlF3 / Al2O3, but are nano-particled to form a coating layer at the level of a quasi-compound (Fig. 2). Such an artificial film layer or coating layer protects zinc metal from a weakly acidic electrolyte, reduces desolvation energy, minimizes side reactions, and selectively accelerates ion transport. Therefore, the zinc anode including the artificial film layer of the present invention has improved stability, thereby promoting continuous Zn plating and stripping.

[0044] The thickness of the above coating layer can be controlled, particularly by the immersion time.

[0045] The artificial film layer on the zinc anode suppresses the HER reaction on the zinc anode surface due to its strong interaction with water. These characteristics, combined with its uniform ion and electron transfer characteristics, ensure a uniform deposition reaction of the zinc anode during charging. Furthermore, improved overvoltage enhances the electrochemical zinc deposition / desorption reactivity, resulting in an aqueous zinc secondary battery with excellent stability and performance.

[0046] Accordingly, the present invention provides a zinc ion secondary battery using a zinc anode having an artificial film layer formed thereon. The zinc ion secondary battery includes a positive electrode, a zinc anode including an artificial film layer, a separator positioned between the positive electrode and the negative electrode, and an aqueous electrolyte.

[0047] The above anode may include at least one selected from the group consisting of MnO2, V2O5, ZnMn2O4, ZnCo2O4, metal vanadates, Br2 / C and I2 / C, and preferably may include MnO2.

[0048] The above-mentioned separator may include a Nafion-based high-density separator, a non-woven separator such as PI (polyimide) or PET (polyethylene terephthalate), a cellulose-based separator, a ceramic-coated separator, glass fiber, etc. Preferably, it may include glass fiber.

[0049] The above-mentioned aqueous electrolyte may include at least one selected from the group consisting of ZnSO4, MnSO4, C2F6O6S2Zn, CoSO4, Mn(CF3SO3)2, ZnBr2, ZnI2, and Na2SO4, and preferably may include ZnSO4 and MnSO4.

[0050]

[0051] The present invention is described in more detail through the following examples. However, the present invention should not be considered limited thereto.

[0052]

[0053] Example 1

[0054] An AlF3 solution was prepared by dissolving 0.2 mmol of Al(NO3)3 and 0.8 mmol of NH4F in 50 mL of water. Zinc metal foil was immersed in the prepared solution for 1 minute at room temperature. The zinc foil was then washed several times with water and ethanol and stored at 60 o A zinc anode with an artificial film layer formed by drying in C was manufactured.

[0055]

[0056] Example 2

[0057] A zinc anode having an artificial film layer formed thereon was manufactured in the same manner as in Example 1, except that the zinc metal foil was immersed for 10 minutes.

[0058]

[0059] Example 3

[0060] A zinc anode having an artificial film layer formed thereon was manufactured in the same manner as in Example 1, except that the zinc metal foil was immersed for 1 hour.

[0061]

[0062] Example 4

[0063] A zinc anode having an artificial film layer formed thereon was manufactured in the same manner as in Example 1, except that the zinc metal foil was immersed for 12 hours.

[0064]

[0065] Example 5

[0066] A zinc anode having an artificial film layer formed thereon was manufactured in the same manner as in Example 2, except that Ca(NO3)3 was used instead of Al(NO3)3 in Example 2.

[0067]

[0068] Example 6

[0069] A zinc anode having an artificial film layer formed thereon was manufactured in the same manner as in Example 2, except that Mg(NO3)3 was used instead of Al(NO3)3 in Example 2.

[0070]

[0071] Example 7

[0072] A zinc anode having an artificial film layer formed thereon was manufactured in the same manner as in Example 2, except that La(NO3)3 was used instead of Al(NO3)3 in Example 2.

[0073]

[0074] Example 8

[0075] A zinc anode having an artificial film layer formed thereon was manufactured in the same manner as in Example 7, except that (NH4)Cl was used instead of NH4F in Example 7.

[0076]

[0077] Comparative example

[0078] Zinc foil without an artificial film layer was used as is.

[0079]

[0080] Measurement and Evaluation

[0081] In order to measure the thickness of the artificial film layer of the zinc cathode formed in Examples 1 to 4 above, the cross-section of the zinc metal was observed using SEM (Fig. 3).

[0082] This shows that an artificial film layer with a thickness of about 1 micrometer is formed on the surface of the zinc cathode.

[0083]

[0084] After confirming the morphology of the artificial film layer, depth analysis was performed using TOF-SIMS (Time of flight secondary ion mass spectrometry) to identify the components present in the film layer and the compositional changes according to thickness. The results are shown in Fig. 4.

[0085] Depth analysis revealed that fluorine was abundant in the uppermost layer of the film, and that the relative proportion of oxygen increased with depth. This suggests that the formed film layer has a structure in which AlF3 is present in a gradient from the upper layer to the inner layer within the Al2O3 bulk structure.

[0086]

[0087] To determine whether the film layer affects the Zn plating morphology, changes in Zn morphology with increasing deposition capacity were analyzed using SEM. The experiment was conducted using a symmetrical cell. The symmetrical cell was fabricated as a coin cell using a zinc anode with an artificial film layer manufactured in the example and an aqueous electrolyte containing 2 M ZnSO4 and 0.2 M MnSO4. The results are shown in Fig. 5.

[0088] In the case of the zinc anode of the comparative example, it was found that non-uniform nuclei were formed and grew in a form with mossy and dendritic morphology, whereas in the case of the zinc anode of the example with the introduction of the film layer, it was found that nuclei with larger sizes were formed more uniformly and grew in a form with a flatter morphology compared to the zinc anode of the comparative example. Through a comparison of these images, it was confirmed that the film layer can play a role in guiding ions or elements during the Zn plating process.

[0089]

[0090] Figures 6 and 7 are 1.0 mA / cm 2 Voltage hysteresis during symmetric cell cycling from a comparative example zinc anode and an exemplary example zinc anode is shown.

[0091] Symmetrical cell from zinc cathode example 1mA / cm 2While the voltage profile of the symmetrical cell of the comparative zinc anode showed a stable shape with small hysteresis for more than 1000 hours, the voltage hysteresis of the symmetrical cell of the comparative zinc anode was found to fluctuate significantly within 50 hours due to the occurrence of an internal short circuit caused by dendritic growth of the zinc anode.

[0092] In addition, as a result of comparing the overpotential for the plating reaction of the film layer, it was confirmed that the nucleation overpotential of the zinc cathode with the film was reduced, and it was confirmed that the overpotential for the plating reaction was also significantly reduced.

[0093]

[0094] Next, using the zinc anodes of Example 2 and Comparative Example, a pouch cell was fabricated using an aqueous electrolyte containing 2 M ZnSO4 and 0.2 M MnSO4 dissolved therein, and a cathode active material MnO2 65 wt%, a conductive material 30 wt%, and a PTFE binder 5 wt% coated on a Ti foil. As a result of evaluating the performance of the fabricated pouch cell, it was confirmed that the life characteristics of the battery were improved when the zinc anode of Example was applied (Fig. 8).

[0095]

[0096] The present invention is being filed with the support of the tasks described below.

[0097] - Assignment ID: RS-2024-00407015

[0098] - Ministry name: Ministry of Science and ICT

[0099] - Project Management (Professional) Organization Name: National Research Foundation of Korea

[0100] - Research Project Name: Source Technology Development Project

[0101] - Research Project Name: (C) Development of Advanced Technology for 120 Wh / kg Ultra-Long-Life Aqueous Zinc Secondary Battery Based on Multielectron Iodine Reaction

[0102] - Project implementation organization name: Korea Electrotechnology Research Institute

[0103] Research period: April 1, 2024 - December 31, 2028

Claims

1. A step of immersing zinc metal in a non-metallic salt solution to form an artificial film layer on the surface of the zinc cathode through a chemical reaction; and A method for manufacturing a zinc negative electrode of a zinc ion secondary battery, comprising washing and drying steps.

2. In paragraph 1, The above inorganic metal salt solution Ca(OH)2, Mg(OH)2, Ba(OH)2, Al(OH) 3, La(OH) 3, CaCl2, MgCl2, BaCl2, AlCl3, LaCl 3, CaF2, MgF2, BaF2, AlF3, LaF 3, CaCO3, MgCO3, BaCO3, Al2(CO3) 3, La(CO3) 3, CaSO4, MgSO4, BaSO4, and Al2(SO4) 3, A metal precursor selected from the group consisting of La2(SO4)3; and A method for manufacturing a zinc anode, characterized in that it comprises at least one selected from the group consisting of (NH4)F, (NH4)Cl, (NH4)Br, alkylammonium ions, phosphonium and alkylphosphonium ions.

3. In paragraph 1, A method for manufacturing a zinc anode, characterized in that the solvent of the above-mentioned inorganic metal salt solution is at least one selected from the group consisting of water, alcohol, NMP (N-methyl-2-pyrrolidone), and THF (tetrahydrofuran).

4. In paragraph 1, A method for manufacturing a zinc anode, characterized in that the concentration of the above-mentioned inorganic metal salt solution is in the range of 1 mM to 5 M.

5. In paragraph 1, A method for manufacturing a zinc anode, characterized in that the immersion time in the step of forming the artificial film layer is in the range of 1 second to 12 hours.

6. A zinc negative electrode for a zinc ion secondary battery manufactured by the method of any one of claims 1 to 5.

7. In paragraph 6, A zinc anode characterized in that the zinc anode includes an artificial film layer having a thickness of 0.1 to 100 μm on the surface.

8. In paragraph 7, The above artificial film layer is made of AlF3 and Al2O3, AlCl3 and Al2O3, AlBr3 and Al2O3, A zinc anode characterized in that it is a composite nano-compound, comprising at least one selected from the group consisting of MgF2 and MgO, CaF2 and CaO, BaF2 and BaO, and LaF3 and La2O3.

9. A zinc anode of clause 6 is characterized in that it forms a cathode by coating a conductive substrate selected from the group consisting of Al foil, Ni foil, Fe foil, titanium foil, titanium foam, carbon nanotube (CNT), carbon nanofiber, carbon fiber, graphene foam, and graphene fiber.

10. A zinc ion secondary battery comprising a zinc negative electrode, a positive electrode, a separator, and an aqueous electrolyte of clause 6.

11. In paragraph 10, A zinc ion secondary battery, characterized in that the positive electrode comprises at least one selected from the group consisting of MnO2, V2O5, ZnMn2O4, ZnCo2O4, metal vanadates, Br2 / C, and I2 / C.

12. In paragraph 10, A zinc ion secondary battery, characterized in that the separator comprises at least one selected from the group consisting of filter paper, glass fiber, polyolefin, and polymer series.

13. In paragraph 10, A zinc ion secondary battery, characterized in that the aqueous electrolyte comprises at least one selected from the group consisting of ZnSO4, MnSO4, C2F6O6S2Zn, CoSO4, Mn(CF3SO3)2, ZnBr2, ZnI2, and Na2SO4.

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