Negative electrode for aqueous zinc battery including network-type polymer coating layer and aqueous zinc battery including same

Abstract

The present invention relates to a negative electrode for an aqueous zinc battery, the negative electrode comprising a network-type polymer coating layer. Specifically, the negative electrode for an aqueous zinc battery may comprise: a zinc negative electrode; and an amine-based polymer coating layer formed on the surface of the zinc metal.

Description

A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer and an aqueous zinc battery comprising the same

[0001] The present invention relates to a negative electrode for an aqueous zinc battery and an aqueous zinc battery comprising the same.

[0002]

[0003] With the active adoption of large-scale energy storage devices in households, electrochemical energy storage devices are garnering attention. Currently commercialized lithium-ion batteries have limitations that make large-scale application difficult due to limited lithium reserves and organic electrolytes that are unstable and pose high risks.

[0004] As a result, zinc-ion batteries, which possess advantages such as high stability and abundant zinc reserves, are attracting attention as an alternative. However, like lithium-ion batteries, aqueous zinc-ion batteries also suffer from side reactions caused by continuous electrochemical reactions, and there are unresolved issues such as dendrite formation and hydrogen generation and corrosion of the negative electrode due to the aqueous electrolyte.

[0005] Furthermore, the electrochemical reactions occurring during the charging and discharging process of the zinc anode are influenced by electrode surface characteristics, exhibiting significantly different properties, particularly due to non-uniform charge distribution such as the oxide layer on the electrode surface. Additionally, the interfacial resistance between the electrode and the aqueous electrolyte is non-uniform and high. Therefore, resolving these issues is urgent for the large-scale application of aqueous zinc batteries.

[0006]

[0007] The present invention aims to solve the aforementioned conventional problems and to provide a negative electrode for an aqueous zinc battery formed with a hydrophilic amine-based polymer coating layer capable of exhibiting stable charge transfer and surface electrochemical reactions.

[0008] In addition, the present invention aims to provide a method for forming a hydrophilic amine-based polymer coating layer on a zinc cathode through a relatively simple method.

[0009]

[0010] A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer according to one embodiment of the present invention may comprise, in the negative electrode for an aqueous zinc battery: a zinc negative electrode; and an amine-based polymer coating layer formed on the surface of the zinc metal.

[0011] According to one embodiment, the polymer coating layer may comprise branched-polyethyleneimine (b-PEI).

[0012] According to one embodiment, the nitrogen (N) content ratio of the polymer coating layer may be formed to be 8% to 16%.

[0013] According to one embodiment, the oxygen (O) content ratio of the polymer coating layer may be formed to be 16% to 24%.

[0014] According to one embodiment, the zinc cathode is formed of a foil material, and the polymer coating layer may include a network structure.

[0015] According to one embodiment, the polymer coating layer may have a water contact angle of 50° to 80°.

[0016] According to one embodiment, the cathode is 1200 cm⁻¹ on the FT-IR graph. -1 to 1650 cm -1 At least three peaks may be observed in the wavelength range.

[0017] A water-based zinc battery comprising a network-type polymer coating layer according to another embodiment comprises: a negative electrode; a positive electrode spaced apart from the negative electrode; and a water-based electrolyte impregnating the positive electrode and the negative electrode and having ion conductivity; wherein the negative electrode may comprise zinc metal; and an amine-based polymer coating layer formed on the surface of the zinc metal.

[0018] According to one embodiment, the aqueous zinc battery has 3 mA cm -2 , 1 mAh cm -2 After 100 charge-discharge cycles under symmetric cell conditions, the (002) peak of zinc in the XRD pattern may appear larger than the (100) peak.

[0019] A method for manufacturing a negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer according to another embodiment may include the steps of: preparing a hydrophilic amine-based polymer solution; immersing a zinc negative electrode foil in the polymer solution; washing the immersed zinc negative electrode foil; and post-treating the washed zinc negative electrode foil in a vacuum chamber.

[0020] According to one embodiment, in the step of preparing the polymer solution; wherein the polymer solution may contain 3% to 10% by weight of an amine-based polymer.

[0021] According to one embodiment, the molecular weight of the polymer is 15,000 g mol -1 Up to 40,000 g mol -1 It could be.

[0022] According to one embodiment, the step of immersing the zinc cathode foil in the polymer solution may be to immerse the zinc cathode foil in the polymer solution at 10°C to 50°C for 36 to 60 hours.

[0023]

[0024] The present invention has the effect of suppressing surface side reactions and the formation of zinc dendrites through a zinc cathode formed with a hydrophilic polymer coating layer.

[0025] In addition, the aqueous zinc battery comprising a zinc negative electrode formed with a hydrophilic polymer coating layer according to the present invention has the effect of maintaining high stability and enabling long-term operation.

[0026] However, the effects of the present invention are not limited to those described above, but include all effects naturally realized through the various configurations proposed in the present invention.

[0027]

[0028] FIG. 1 is a schematic diagram showing the formation of a polymer coating layer according to a dip-coating method according to one embodiment of the present invention.

[0029] Figure 2a is an XPS graph of a polymer coating layer formed by performing dip-coating before (a), and tip-coating for 24 hours (b), 48 hours (c), and 72 hours (d).

[0030] Figure 2b is a graph showing the nitrogen (N) content ratio of the polymer coating layer according to the dip-coating time.

[0031] Figure 3 shows a photograph (a) of a zinc cathode foil with a polymer coating layer formed and a zinc cathode foil without a polymer coating layer formed, and SEM and AFM images (b) of each surface.

[0032] Figure 4 is an XPS and FT-IR graph of a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer.

[0033] Figure 5 is a photograph showing the water contact angle on the surface of a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer formed.

[0034] Figure 6 is an electrochemical impedance spectroscopy graph of a zinc cathode foil with a polymer coating layer formed and a zinc cathode foil without a polymer coating layer formed.

[0035] FIG. 7 shows a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer formed at 3 mA cm -2 This is an SEM image showing zinc deposition observed for 0 min, 10 min, and 30 to 60 min under current density conditions.

[0036] Figure 8 is a CSI graph showing the zinc deposition on a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer.

[0037] Figure 9 is a graph of the long-term stability evaluation of a symmetric cell containing a zinc cathode with a polymer coating layer formed and a symmetric cell containing a zinc cathode without a polymer coating layer formed.

[0038] Figure 10 is an XRD pattern graph of a symmetric cell containing a zinc cathode with a polymer coating layer formed and a zinc cathode without a polymer coating layer formed, before driving (a) and after driving 100 cycles (b).

[0039] Figure 11 is an electrochemical impedance spectrocopy graph of a full cell (a) containing a zinc cathode without a polymer coating layer and a full cell (b) containing a zinc cathode with a polymer coating layer formed, driven for 10, 30, and 100 cycles.

[0040] Figure 12 is a graph showing the capacitance and Coulomb efficiency of a full cell containing a zinc cathode with a polymer coating layer formed and a full cell containing a zinc cathode without a polymer coating layer formed.

[0041] Figure 13 is a graph showing the capacitance and Coulomb efficiency of a full cell containing a zinc cathode with a polymer coating layer formed and a full cell containing a zinc cathode without a polymer coating layer formed.

[0042]

[0043] The embodiments of the present invention are illustrative for the purpose of explaining the technical concept of the present invention. The scope of rights according to the present invention is not limited to the embodiments presented below or the specific description thereof.

[0044] All technical and scientific terms used in this invention, unless otherwise defined, have the meaning generally understood by those skilled in the art to which this invention pertains. All terms used in this invention are selected for the purpose of further explaining this invention and are not selected to limit the scope of rights according to this invention.

[0045] Expressions such as "comprising," "having," "having," etc. used in the present invention should be understood as open-ended terms implying the possibility of including other embodiments, unless otherwise stated in the phrase or sentence containing such expressions.

[0046] Unless otherwise stated, singular expressions described in the present invention may include the meaning of the plural form, and this applies likewise to singular expressions described in the claims.

[0047]

[0048] A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer according to one embodiment of the present invention may comprise, in the negative electrode for an aqueous zinc battery: a zinc negative electrode; and an amine-based polymer coating layer formed on the surface of the zinc metal.

[0049] FIG. 1 is a schematic diagram showing the formation of a polymer coating layer according to a dip-coating method according to one embodiment of the present invention.

[0050] The above-mentioned cathode may preferably include zinc. For example, when iron metal is applied as the cathode of an aqueous zinc battery, the standard electrode potential is higher than that of zinc, resulting in a high degree of oxidation, easy corrosion in basic environments, and active formation of an iron oxide passivation layer, which may make it unsuitable for reducing conductivity and electrochemical active area.

[0051] According to one embodiment, the zinc cathode may include a hydrophilic polymer coating layer on its surface. The hydrophilic polymer coating layer may include a polymer formed by polymerizing with an amine-based monomer. The polymer may include one or more of primary, secondary, and tertiary amines. The polymer may be a polymer that contains 10 mol% or more of one or more of primary, secondary, and tertiary amines and has one or more of a linear, branched, or dendritic structure.

[0052] Among the structures of the polymers mentioned above, the linear structure allows for easy control of viscosity and film thickness and is advantageous for forming smooth thin films, but its mechanical durability and peel resistance may be relatively lower compared to other structures. The branched structure has high metal surface adhesion and fixation strength due to the high density and multi-point coordination of amines, and thus can exhibit excellent peel resistance even in aqueous systems. The dendritic structure allows for the uniform substitution of terminal amines at ultra-high density, which can be advantageous for precise composition control of ultrathin films, but excessive cases may cause a decrease in ion conductivity. Preferably, the polymer may include a branched structure.

[0053] The above polymer may comprise one or more selected from the group consisting of poly(ethyleneimine), poly(allylamine), poly(vinylamine), poly(amidoamine) dendrimer, chitosan or its derivative, poly(L-lysine), poly(2-(dimethylamino)ethyl (meth)acrylate / acrylamide) (PDMAEMA), poly(4-vinylpyridine) (P4VP), poly(diallylamine), and polydopamine. Preferably, the polymer coating layer may comprise polyethyleneimine.

[0054] According to one embodiment, the polymer coating layer may comprise branched-polyethyleneimine (b-PEI).

[0055] The polymer coating layer of the present invention is technically differentiated from the conventional technology of adding branched polyethyleneimine to the electrolyte by forming a hydrophilic polymer coating layer by coating it on the surface of a zinc cathode.

[0056] Since the branched polyethyleneimine (b-PEI) having the above branched structure contains multiple primary and tertiary amines compared to the linear polyethyleneimine, the polymer coating layer containing the branched polyethyleneimine can strongly bind to the zinc cathode.

[0057] Therefore, the polymer coating layer is not separated from the zinc anode even within an aqueous electrolyte and can be stably maintained on the surface of the zinc anode even when the battery is operated. For example, the polymer coating layer may form a coordination bond with the surface of the zinc anode, and through this bond, it may be stably maintained without being easily separated from the surface of the zinc anode.

[0058] As described above, in the polymer coating layer directly bonded to the surface of the zinc anode, the shuttle effect of the branched polyethyleneimine polymer does not occur during the electrochemical reaction process, thereby maintaining high stability even under full cell conditions containing MnO2 as the anode, which enables long-term operation. Since the polymer coating layer can remain on the surface of the zinc anode even after charging and discharging, the long-term stability of the zinc battery can be improved.

[0059] According to one embodiment, the zinc cathode is formed of a foil material, and the polymer coating layer may include a network structure.

[0060] The polymer coating layer may be uniformly formed by self-assembly on the surface of the zinc cathode and may include a porous network structure. Through self-assembly, the polymer coating layer can be formed to have a uniform thickness and structure on the surface of the zinc cathode. Through the network structure, the formation of an oxide film on the surface of the zinc cathode can be reduced, and a uniform charge distribution can be formed while expanding the reaction area. This stabilizes the stripping / plating process of zinc ions, allowing for uniform deposition and desorption of zinc, suppressing 2D diffusion, and inducing 3D diffusion.

[0061] Through the polymer coating layer having the above network structure, the surface potential of the zinc anode is formed uniformly, and the resistance at the electrolyte-electrode interface can be minimized, thereby reducing overvoltage during the charge-discharge process and increasing zinc nucleation sites to induce stable charge transport and surface electrochemical reactions. Through this, zinc ions are uniformly deposited on the surface of the zinc anode, and the formation of dendrites can be suppressed.

[0062] Since the surface area that can be contacted by dissolved zinc ions of the electrolyte is expanded through the polymer coating layer, the affinity with zinc ions can be improved. As a result, side reactions on the surface of the zinc anode can be suppressed, and the capacity and stability of the zinc battery can be improved.

[0063] According to one embodiment, the nitrogen (N) content ratio of the polymer coating layer may be formed to be 8% to 16%. Preferably, the nitrogen content ratio of the polymer coating layer may be 10% to 12%.

[0064] If the nitrogen content of the polymer coating layer is less than 8%, the polymer coating layer may not be able to sufficiently coat the zinc anode, and thus the effect of the polymer coating layer may not be fully exerted. Although the performance of the battery may be improved as the nitrogen content of the polymer coating layer increases, considering the proportion of other elements included in the polymer coating layer, it may be appropriate for the nitrogen content ratio to be less than 16%.

[0065] According to one embodiment, the oxygen (O) content ratio of the polymer coating layer may be formed to be 16% to 24%. Preferably, the oxygen content ratio of the polymer coating layer may be 18% to 22%.

[0066] If the oxygen content ratio of the polymer coating layer is less than 16%, the effect of the polymer coating layer may not be sufficiently exerted. If the oxygen content ratio of the polymer coating layer is 22% or more, the oxide film ratio of the polymer coating layer is too high, so the performance of the battery may not be sufficiently displayed.

[0067] For example, the polymer coating layer may be formed with a thickness in which the nitrogen content is 10% to 12% and the oxygen content is 18% to 22%. The polymer coating layer is formed with a thickness in the nanoscale range, and the effect of the polymer coating layer can be fully exhibited at a thickness containing the aforementioned nitrogen and oxygen content ratios.

[0068] The above amine-based polymer coating layer has polar groups containing amine nitrogen (N) and oxygen (O) that are protonated and hydrated under aqueous conditions to form hydrogen bonds, and zinc (Zn 2+ It can form a self-assembled three-dimensional porous network through coordination interactions with ). Amines undergo protonation (-NH₃) in aqueous and salt electrolytes. 3+ ) and Zn 2+ It can form coordinate bonds with [another component], acting as an anchor for multi-point bonding and inducing the formation of a physical network upon drying. Oxygen-based materials form hydrogen bonds and a hydration layer, increasing hydrophilicity and wettability, and can promote porosity by inducing microphase separation of the coating layer.

[0069] The above-mentioned interactions can contribute to the self-assembly tendency and porous network shape stability during the water-based dip coating and drying stages, thereby mitigating the local concentration of surface current density and electric field in the polymer coating layer, which suppresses dendrite growth and enables the uniform deposition and desorption of zinc.

[0070]

[0071] A method for manufacturing a negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer according to another embodiment may include the steps of: preparing a hydrophilic amine-based polymer solution; immersing a zinc negative electrode foil in the polymer solution; washing the immersed zinc negative electrode foil; and post-treating the washed zinc negative electrode foil in a vacuum chamber.

[0072] The present invention is characterized by the ability to form a polymer coating layer by directly bonding a polymer to the electrode surface in a relatively simple manner through a dip-coating method in which a zinc cathode foil is immersed in a polymer solution. The composition of the polymer coating layer is as described above.

[0073] According to one embodiment, in the step of preparing the polymer solution, the polymer solution may contain 3% to 10% by weight of an amine-based polymer. Preferably, the polymer solution may contain 3% to 7% by weight of an amine-based polymer. If the amine-based polymer is contained in an amount less than 3% by weight, a polymer coating layer may not be properly formed on the surface of the zinc cathode. If the amine-based polymer is contained in an amount exceeding 10% by weight, the polymer coating layer may instead be formed unevenly.

[0074] According to one embodiment, the molecular weight of the polymer is 15,000 g mol -1 Up to 40,000 g mol -1 It may be. Preferably, the molecular weight of the polymer is 20,000 g mol -1 Up to 30,000 g mol -1 When this happens, the polymer coating layer can be effectively formed.

[0075] According to one embodiment, the polymer chain may have a branched structure. By forming coordination bonds, the polymer chain with the branched structure can effectively form a polymer coating layer on the cathode surface. The polymer solution may be prepared using a hydrophilic solvent, and for example, the hydrophilic solvent may be water.

[0076] The step of preparing the polymer solution may involve stirring the polymer solution at a temperature of 10°C to 50°C and at 100 rpm to 400 rpm for 30 minutes to 2 hours.

[0077] According to one embodiment, the step of immersing the zinc cathode foil in the polymer solution may be to immerse the zinc cathode foil in the polymer solution at 10°C to 50°C for 36 to 60 hours.

[0078] The step of immersing in the polymer solution may be to immerse the zinc cathode foil in the polymer solution and stir at 100 rpm to 400 rpm.

[0079] According to one embodiment, the step of washing the immersed zinc cathode foil may be to wash the zinc cathode foil immersed in the polymer solution with one or more of deionized water (DI water) and ethanol.

[0080] According to one embodiment, the step of post-processing the washed zinc cathode foil in a vacuum chamber may be to store the zinc cathode foil in a vacuum chamber at room temperature.

[0081] The polymer coating layer after the washing and post-treatment steps described above is in a state where the hydrophilic solvent of the polymer solution has evaporated, and the polymer coating layer may contain 97% or more of an amine-based polymer. Preferably, the polymer coating layer may contain 99% or more of an amine-based polymer.

[0082]

[0083] A water-based zinc battery comprising a network-type polymer coating layer according to another embodiment comprises: a negative electrode; a positive electrode spaced apart from the negative electrode; and a water-based electrolyte impregnating the positive electrode and the negative electrode and having ion conductivity; wherein the negative electrode may comprise zinc metal; and an amine-based polymer coating layer formed on the surface of the zinc metal.

[0084] The amine-based polymer coating layer formed on the surface of the zinc metal is as described above. The composition of the anode is not specifically limited in the present invention and may include any composition of the anode that can be applied to an aqueous zinc battery.

[0085] The above aqueous electrolyte is not particularly limited in the present invention, but as an example, the above aqueous electrolyte may be water. As an example, the above aqueous electrolyte may be water in which 3M ZnSO4 and 0.3M MnSO4 are dissolved.

[0086]

[0087] The present invention will be explained in more detail through the following examples. However, these examples represent some experimental methods and configurations to illustrate the invention, and the scope of the invention is not limited to these examples.

[0088]

[0089] Preparation Example 1: Formation of a polymer coating layer on a zinc cathode foil

[0090] b-PEI(Mw=25,000 g mol -1 5g of ) was placed in a 250mL beaker, and 95g of H2O was added. To prevent evaporation, the opening of the beaker was sealed, and the mixture was stirred at 200 rpm for 1 hour at a temperature of 25℃.

[0091] A 2 x 4 cm zinc metal foil was washed with ethanol, acetone, and deionized water in that order and dried. A 13 mm stirring bar and a 2.5 x 5 cm slide glass were placed in a 30 mL vial in that order. 30 mL of a 5 wt% aqueous solution of b-PEI was added to the vial, and the washed and dried zinc cathode foil was placed on a tilted slide glass. The mixture was then stirred at 200 rpm at 25°C for 24 to 72 hours.

[0092] A zinc cathode foil with a polymer coating layer containing b-PEI was washed with deionized water (DI water) and ethanol in that order and blown with N2 gas. Then, the zinc cathode foil with the polymer coating layer formed was stored in a vacuum chamber at room temperature to prevent the surface from deteriorating.

[0093]

[0094] Comparative Example 1: Zinc cathode foil without a polymer coating layer

[0095] As a comparative example, a zinc cathode foil without a polymer coating layer was prepared by washing a 2x4 cm zinc metal foil with deionized water, ethanol, and acetone in that order and drying it.

[0096]

[0097] Experimental Example 1: Formation of a polymer coating layer according to dip-coating time

[0098] A polymer coating layer containing b-PEI was formed on the surface of a zinc cathode foil according to Preparation Example 1 above. To confirm the effect of forming the polymer coating layer according to the dip-coating time, the dip-coating time was varied to 24 hours, 48 ​​hours, and 72 hours.

[0099] Figure 2a is an XPS graph of a polymer coating layer formed by performing dip-coating before (a), and tip-coating for 24 hours (b), 48 hours (c), and 72 hours (d).

[0100] Figure 2b is a graph showing the nitrogen (N) content ratio of the polymer coating layer according to the dip-coating time.

[0101] Compared to before the polymer coating layer was formed on the surface of the zinc cathode foil, the XPS graph when the polymer coating layer was formed via the dip-coating method showed high intensity in the range of 300 eV to 800 eV or exhibited different patterns.

[0102] Through the above results, it was confirmed that the polymer coating layer formed on the surface of the zinc cathode foil exhibits different nitrogen and oxygen content ratios depending on the dip-coating time. Since the polymer coating layer formed by 48 hours of dip-coating contained the most appropriate nitrogen and oxygen content ratio, it was confirmed that 48 hours is the most appropriate dip-coating time.

[0103]

[0104] Experimental Example 2: Evaluation of Polymer Coating Layer Formation

[0105] Figure 3 shows a photograph (a) of a zinc cathode foil with a polymer coating layer formed and a zinc cathode foil without a polymer coating layer formed, and SEM and AFM images (b) of each surface.

[0106] As can be seen in the AFM image, the surface of the zinc cathode foil without a polymer coating layer (bare Zn foil) was found to have irregular height variations.

[0107] However, it was confirmed that the surface of the zinc cathode foil (b-PEI@Zn foil) with a polymer coating layer formed through dip-coating for 48 hours had multiple grains and had a uniform height compared to the surface of the zinc cathode foil without a polymer coating layer.

[0108] Figure 4 is an XPS and FT-IR graph of a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer.

[0109] Compared to the XPS graph (a) of a zinc cathode foil without a polymer coating layer formed, the XPS graph (b) of a zinc cathode foil with a polymer coating layer formed through dip-coating for 48 hours showed high intensity in the range of 500 eV to 800 eV.

[0110] According to one embodiment, the cathode is 1200 cm⁻¹ on the FT-IR graph.-1 to 1650 cm -1 At least three peaks may be observed in the wavelength range.

[0111] In the FT-IR graph (b) of the zinc cathode foil with a polymer coating layer formed, at 1200 cm⁻¹ -1 to 1650 cm -1 Three peaks were observed in the wavelength range. The above peaks represent NH, CH, and CN bonds, which were not detected in the FT-IR graph (a) of the zinc cathode foil without a polymer coating layer formed. Through the above peaks, it was confirmed that a polymer coating layer containing b-PEI can be well bonded and formed on the surface of the zinc cathode foil even through a dip-coating method.

[0112]

[0113] Figure 5 is a photograph showing the water contact angle on the surface of a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer formed.

[0114] According to one embodiment, the polymer coating layer may have a water contact angle of 50° to 80°.

[0115] The water contact angles on the surfaces of a zinc cathode foil (b-PEI@Zn) with a polymer coating layer formed via dip-coating for 48 hours and a zinc cathode foil (Bare Zn) without a polymer coating layer were measured according to the ASTM D5946 standard test method. The water contact angle on the surface of the zinc cathode foil without a polymer coating layer was found to be 86°, while the water contact angle on the surface of the zinc cathode foil with a polymer coating layer was found to be 54°. This confirmed that the surface of the zinc cathode foil with a polymer coating layer exhibited greater hydrophilicity due to the polymer coating layer.

[0116]

[0117] Experimental Example 3: Evaluation of Electrochemical Performance of Zinc Anode Foil with Polymer Coating Layer

[0118] Figure 6 is an electrochemical impedance spectroscopy graph of a zinc cathode foil with a polymer coating layer formed and a zinc cathode foil without a polymer coating layer formed.

[0119] It was confirmed that the EIS graph of a zinc cathode foil without a polymer coating layer (bare Zn) appeared in the shape of a semicircle with a larger diameter than the EIS graph of a zinc cathode foil (b-PEI@Zn) with a polymer coating layer formed through dip-coating for 48 hours.

[0120] Through this, it was confirmed that the zinc cathode foil formed with a polymer coating layer exhibited lower resistance and allowed for freer charge transfer. Additionally, it was confirmed that the polymer coating layer inhibited electrochemical reactions, thereby reducing zinc corrosion.

[0121] FIG. 7 shows a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer formed at 3 mA cm -2 This is an SEM image showing zinc deposition observed for 0 min, 10 min, and 30 to 60 min under current density conditions.

[0122] For a zinc anode foil (bare Zn) without a polymer coating layer, zinc began to be deposited irregularly on the surface of the zinc anode foil after 10 minutes, and it was confirmed that the zinc deposition had grown further after 60 minutes.

[0123] On the other hand, for the zinc anode foil (b-PEI@Zn) in which a polymer coating layer was formed through dip-coating for 48 hours, no zinc deposition was observed on the surface of the zinc anode foil even after 60 minutes. This confirmed that the polymer coating layer can effectively suppress zinc deposition.

[0124] Figure 8 is a CSI graph showing the zinc deposition on a zinc cathode foil (a) without a polymer coating layer and a zinc cathode foil (b) with a polymer coating layer.

[0125] A zinc cathode foil without a polymer coating layer and a zinc cathode foil with a polymer coating layer at 3 mA cm -2 current density, 1 mAh cm -2 The device was charged and discharged for 20 cycles at capacity, and the surface shape was measured and the roughness was quantified through CSI (coherence scanning interferometry).

[0126] In the case of a zinc cathode foil without a polymer coating layer, zinc dendrites were observed to have grown through the surface shape after charging and discharging, and it was confirmed that the surface roughness value (Sq) also increased significantly.

[0127] In the case of a zinc anode foil with a polymer coating layer, it was confirmed that the surface morphology before and after charging and discharging was similar, and the surface roughness value (Sq) changed very little. Through this, it was confirmed that in the case of a zinc anode with a polymer coating layer, the formation of dendrites was suppressed and prevented during the zinc ion deposition process.

[0128]

[0129] Example 4: Performance evaluation of a symmetrical cell comprising a zinc cathode with a polymer coating layer

[0130] Symmetric Zn||Zn cells were prepared comprising a zinc cathode with a polymer coating layer formed via dip-coating for 48 hours and a zinc cathode without a polymer coating layer. The symmetric cells were subjected to 1 mA cm⁻¹. -2 , 1 mAh cm -2 and 3 mA cm -2 , 1 mAh cm -2 Performance was evaluated by driving under certain conditions.

[0131] Figure 9 is a graph of the long-term stability evaluation of a symmetric cell containing a zinc cathode with a polymer coating layer formed and a symmetric cell containing a zinc cathode without a polymer coating layer formed.

[0132] 1 mA cm -2 , 1 mAh cm -2 It was confirmed that in a symmetric cell under conditions, a battery containing a zinc anode without a polymer coating layer (Bare Zn) stops operating within 100 hours, but a battery containing a zinc anode with a polymer coating layer (b-PEI@Zn) operates for more than 400 hours.

[0133] According to one embodiment, the aqueous zinc battery has 3 mA cm -2 , 1 mAh cm -2 It may be maintained for more than 1400 hours in the symmetric cell of the condition.

[0134] 3 mA cm -2 , 1 mAh cm -2 It was confirmed that in a symmetric cell under the conditions, a battery containing a zinc anode without a polymer coating layer exhibited an unstable voltage and stopped operating after about 100 hours of operation, whereas a battery containing a zinc anode with a polymer coating layer operated with a stable voltage for more than 1400 hours. Through the above results, it was confirmed that the long-term stability of the battery containing a zinc anode with a polymer coating layer was significantly improved.

[0135] A symmetric cell containing a zinc cathode with a polymer coating layer formed via dip-coating for 48 hours and a zinc cathode without a polymer coating layer at 3 mA cm -2 , 1 mAh cm -2 100 cycles were run under conditions, and XRD patterns were measured before and after the run.

[0136] Figure 10 is an XRD pattern graph of a symmetric cell containing a zinc cathode with a polymer coating layer formed and a zinc cathode without a polymer coating layer formed, before driving (a) and after driving 100 cycles (b).

[0137] According to one embodiment, the aqueous zinc battery may have a (002) peak of zinc that is larger than the (100) peak in the XRD pattern after 100 charge-discharge cycles under symmetric cell conditions.

[0138] In the XRD pattern of a symmetric cell containing a zinc anode (Bare Zn anode) without a polymer coating layer, after 100 cycles of operation, both the (002) peak and the (100) peak of zinc were elevated, and it was confirmed that the (100) peak was higher than the (002) peak.

[0139] In the XRD pattern of a symmetric cell containing a zinc anode (b-PEI@Zn anode) with a polymer coating layer formed thereon, it was confirmed that the (002) peak of zinc, which had a small height before driving, rose significantly after 100 cycles of driving and appeared higher than the (100) peak. In the zinc anode with a polymer coating layer formed thereon, it was confirmed that the (002) peak after driving rose significantly because zinc was more reversibly deposited / stripped during the zinc ion plating / stripping process, resulting in fewer side reactions.

[0140]

[0141] Example 5: Performance evaluation of a full cell including a zinc cathode with a polymer coating layer

[0142] Full cells (a-MnO2||Zn Full cells) were prepared including a zinc cathode with a polymer coating layer formed by dip-coating for 48 hours and a zinc cathode without a polymer coating layer formed.

[0143] Figure 11 is an electrochemical impedance spectrocopy graph of a full cell (a) containing a zinc cathode without a polymer coating layer and a full cell (b) containing a zinc cathode with a polymer coating layer formed, driven for 10, 30, and 100 cycles.

[0144] A full cell (a-MnO2||Bare Zn) containing a zinc cathode without a polymer coating layer exhibited low initial resistance before driving, but showed a significant increase in impedance as the cycle increased, resulting in a degradation of electrode performance and an increase in resistance.

[0145] It was confirmed that a full cell (a-MnO2||b-PEI@Zn) containing a zinc anode with a polymer coating layer had a smaller increase in impedance compared to a full cell containing a zinc anode without a polymer coating layer. Through this, it was confirmed that the full cell containing a zinc anode with a polymer coating layer has improved cycling stability and can maintain low impedance even after 100 cycles of operation.

[0146] Figure 12 is a graph showing the capacitance and Coulomb efficiency of a full cell containing a zinc cathode with a polymer coating layer formed and a full cell containing a zinc cathode without a polymer coating layer formed.

[0147] According to one embodiment, the aqueous zinc battery has 0.1 A g -1 250 mAh g after 200 charge-discharge cycles under full cell conditions -1 It may be maintaining a capacity greater than that.

[0148] According to one embodiment, the aqueous zinc battery has 0.1 A g -1 It may exhibit a Coulomb efficiency of 98% or higher after 200 charge-discharge cycles under full cell conditions.

[0149] It was confirmed that the full cell (a-MnO2||Bare Zn) containing a zinc anode without a polymer coating layer stopped operating after more than 100 cycles, but the full cell (a-MnO2||b-PEI@Zn) containing a zinc anode with a polymer coating layer formed through dip-coating for 48 hours operated for more than 200 cycles, and the battery stability was improved.

[0150] A full cell containing a zinc cathode with a polymer coating layer formed thereon has 0.1 A g compared to a full cell containing a zinc cathode without a polymer coating layer formed thereon. -1 It was confirmed that it exhibited higher electrical capacitance and Coulomb efficiency under full cell conditions.

[0151] Figure 13 is a graph showing the capacitance and Coulomb efficiency of a full cell containing a zinc cathode with a polymer coating layer formed and a full cell containing a zinc cathode without a polymer coating layer formed.

[0152] According to one embodiment, the aqueous zinc battery has 0.5 A g - 200 mAh g after 300 charge-discharge cycles under full cell conditions of 1 -1 It may be maintaining a capacity greater than that.

[0153] A full cell (a-MnO2||b-PEI@Zn) containing a zinc cathode with a polymer coating layer formed thereon has 0.5 A g compared to a full cell (a-MnO2||Bare Zn) containing a zinc cathode without a polymer coating layer formed thereon. -1 It was confirmed that it exhibited higher electrical capacity and Coulomb efficiency under full cell conditions. Through this, it was confirmed that the long-term stability of the zinc battery was significantly improved due to the formation of a polymer coating layer.

[0154]

[0155] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

1. In a negative electrode for an aqueous zinc battery, zinc cathode; and amine-based polymer coating layer formed on the zinc metal surface; comprising A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

2. In Paragraph 1, The above polymer coating layer comprises branched-polyethyleneimine (b-PEI), A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

3. In Paragraph 1, The nitrogen (N) content ratio of the polymer coating layer is formed to be 8% to 16%. A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

4. In Paragraph 1, The oxygen (O) content ratio of the polymer coating layer is formed to be 16% to 24%. A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

5. In Paragraph 1, The above zinc cathode is formed of foil material, and The above polymer coating layer includes a network structure, A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

6. In Paragraph 1, The above polymer coating layer has a water contact angle of 50° to 80°, A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

7. In Paragraph 1, The above cathode is 1200 cm⁻¹ on the FT-IR graph. -1 to 1650 cm -1 At least three peaks are observed in the wavelength range, A negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

8. Cathode; An anode spaced apart from the above cathode; and A water-based electrolyte having ion conductivity that impregnates the above anode and cathode; comprising, The above cathode is, zinc metal; and amine-based polymer coating layer formed on the zinc metal surface; comprising Aqueous zinc battery including a network-type polymer coating layer.

9. In Paragraph 8, The above aqueous zinc battery is 3 mA cm -2 , 1 mAh cm -2 After 100 charge-discharge cycles under symmetric cell conditions, In the XRD pattern, the (002) peak of zinc appears larger than the (100) peak, Aqueous zinc battery including a network-type polymer coating layer.

10. Step of preparing a hydrophilic amine-based polymer solution; A step of immersing a zinc cathode foil in the polymer solution; A step of washing the above-mentioned immersed zinc cathode foil; and The step of post-processing the above-mentioned washed zinc cathode foil in a vacuum chamber; comprising Method for manufacturing a negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

11. In Paragraph 10, In the step of preparing the above polymer solution; The above polymer solution comprises 3% to 10% by weight of an amine-based polymer, Method for manufacturing a negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

12. In Paragraph 10, The molecular weight of the above polymer is 15,000 g mol -1 Up to 40,000 g mol -1 and being branched, Method for manufacturing a negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

13. In Paragraph 10, The step of immersing the zinc cathode foil in the polymer solution; is, Immersing the above zinc cathode foil in a polymer solution at 10°C to 50°C for 36 to 60 hours, Method for manufacturing a negative electrode for an aqueous zinc battery comprising a network-type polymer coating layer.

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