Aluminum electrochemical energy battery

Abstract

The present invention relates to an aluminum electrochemical energy battery and, specifically, to an aluminum electrochemical energy battery comprising an electrolyte that includes a catholyte, and thus does not require catalysts and separators, reduces aluminum corrosion and can improve cell performance. The present invention relates to the aluminum electrochemical energy battery comprising a cathode, an anode, and the electrolyte that includes a catholyte, wherein the catholyte is a salt or ion including SxOy. The aluminum electrochemical energy battery according to one embodiment of the present invention comprises the electrolyte that includes the catholyte, and thus does not require catalysts and separators and can improve cell performance.

Description

Aluminum electrochemical energy cell

[0001] The present invention relates to an aluminum electrochemical energy cell, and more particularly, to an aluminum electrochemical energy cell that does not require a catalyst and a separator by including an electrolyte including an anode solution, thereby reducing aluminum corrosion and improving cell performance.

[0002] Aluminum-air batteries (AABs) have recently attracted considerable attention as potential next-generation batteries due to their cost-effectiveness and ability to provide high energy storage capabilities. Primary Al-air batteries typically consist of an Al cathode, an air anode, and an aqueous electrolyte. They have a high energy density (8,131 Wh / kg). Al ), lightweight structure and safety make Al-air batteries beneficial in various applications such as electric vehicles, telecommunications and medical equipment.

[0003] However, despite these advantages, Al-air batteries still face challenges such as high corrosion rate of Al cathodes, rapid self-discharge, and cost and performance of cathode catalysts for practical applications.

[0004] To achieve acceptable power density in Al-air batteries, an alkaline electrolyte such as KOH or NaOH may generally be preferred over a neutral electrolyte (NaCl).

[0005] However, the use of these strongly alkaline electrolytes can cause hydrogen evolution reaction (HER) at the cathode. This severe HER reduces the actual specific capacity of conventional AAB to less than 60% of the theoretical value. Therefore, suppressing HER caused by the Al cathode is crucial to improving the specific capacity of AAB.

[0006] To address the corrosion problem of Al cathodes, the following strategies were devised:

[0007] The first is to increase the overpotential of the HER by alloying Al with metals such as Mg, Sn, In, and Ga. The second is to add corrosion inhibitors, such as inorganic or organic inhibitors, to the alkaline electrolyte. These inhibitors can limit the rate of water molecule movement, preventing direct contact between water and the cathode.

[0008] However, while these methods effectively reduce corrosion of the aluminum cathode to a certain extent, they also have their own drawbacks. Alloying aluminum with other metals or adding corrosion inhibitors increases the overall cost of the system, and the additional steps required to recycle the aluminum oxide can reduce efficiency.

[0009] Meanwhile, oxygen, with its high redox potential, boundless availability, and clean byproduct (water) production after reduction, is frequently used as an anode electron acceptor in AAB. However, despite its ability to directly utilize air oxygen, the air anode used in AAB is often a less effective electron acceptor due to the low solubility of oxygen (7–9 mg / L) at operating temperatures and the poor interaction between the anode and the air surface near the electrode-electrolyte interface. Therefore, noble metals such as platinum (Pt) can be used to accelerate the cleavage of the O=O bond.

[0010] Furthermore, hydrogen peroxide can also serve as an interesting electron acceptor for metal batteries, particularly in applications where air is unavailable, such as submarines and underwater drones. However, due to its low electron transfer kinetics and mass transfer efficiency, it relies on precious metal catalysts for better performance. Consequently, improving the electron acceptor in the anode at the lowest possible cost is crucial for research and development.

[0011] Accordingly, there was a need for research and development of an electrochemical energy cell that reduces corrosion of aluminum electrodes and is economical and has high cell stability.

[0012] The technical problem to be achieved by the present invention is to provide an aluminum electrochemical energy cell that does not require a catalyst and a separator, reduces aluminum corrosion, and improves cell performance.

[0013] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0014] One embodiment of the present invention comprises an electrolyte including a positive electrode; a negative electrode; and an anodic solution, wherein the anodic solution is S x O y An aluminum electrochemical energy cell is provided, which is a salt or ion containing .

[0015] According to one embodiment of the present invention, the S x O y It may be at least one selected from the group consisting of S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, SO5 and combinations thereof.

[0016] According to one embodiment of the present invention, the S x O y Silver persulfate (Na2S2O8) or persulfate ion (S2O8 2- ) may be.

[0017] According to one embodiment of the present invention, the electrolyte may be at least one selected from the group consisting of sodium hydroxide, sodium chloride, potassium chloride, potassium hydroxide, and the like.

[0018] According to one embodiment of the present invention, the concentration of the positive electrode solution may be 0.1 M or more and 2.0 M or less.

[0019] According to one embodiment of the present invention, the concentration of the electrolyte may be 0.5 M or more and 5.0 M or less.

[0020] According to one embodiment of the present invention, the concentration ratio of the positive electrode solution and the electrolyte solution may be 1:0.5 or more and 3:1 or less.

[0021] According to one embodiment of the present invention, the cathode may include aluminum.

[0022] According to one embodiment of the present invention, the anode may include at least one selected from the group consisting of carbon cloth (CC), carbon felt (CF), nickel foam (NF), graphite, and stainless steel (SS).

[0023] According to one embodiment of the present invention, the anode may not contain a catalyst.

[0024] According to one embodiment of the present invention, the content of the positive electrode solution may be 10 wt% or more and less than 50 wt% based on the total weight of the electrolyte.

[0025] According to one embodiment of the present invention, the electrolyte may be in a static, fluid or gel form.

[0026] An aluminum electrochemical energy cell according to one embodiment of the present invention can improve cell performance without requiring a catalyst and a separator by including an electrolyte including an anode solution.

[0027] An aluminum electrochemical energy cell according to one embodiment of the present invention can reduce aluminum corrosion and improve cell performance by including an electrolyte including an anode solution.

[0028] An aluminum electrochemical energy cell according to one embodiment of the present invention can be applied to various fields, including a static, fluid or gel type electrolyte.

[0029] FIG. 1 is a schematic diagram of an aluminum electrochemical energy system (Al-EES) according to one embodiment of the present invention.

[0030] (A) and (B) of FIG. 2 are schematic diagrams of conventional Al-air and Al-EES according to an embodiment of the present invention, (C) shows polarization curves comparing Al-EES with Al-air and Al-H2O2, (D) shows values ​​of polarization and power density curves in various electrolyte and anolyte conditions of Al-EES according to an embodiment of the present invention, (E) shows polarization curves in optimized conditions of Al-EES according to an embodiment of the present invention, (F) shows EIS for various electrolyte and anolyte conditions of Al-EES according to an embodiment of the present invention, (G) shows EIS for various anode conditions of Al-EES according to an embodiment of the present invention, (H) shows voltage-power density of AL-EES with multiple stacks according to an embodiment of the present invention, and (I) shows voltage-power density curves using various electrolyte and anolyte concentrations in Al-EES according to an embodiment of the present invention. The discharge profile at 100 mA is shown, (J) shows the specific flow rate and energy density at various electrolyte and anolyte concentrations of Al-EES according to one embodiment of the present invention, and (K) shows the discharge profile at various currents of Al-EES according to one embodiment of the present invention.

[0031] Figure 3 shows a corrosion study of Al, specifically, (A) shows a hydrogen evolution test analyzed by a drainage method using electrolyte and anolyte of different concentrations, (B) shows ELS analysis, (C) shows potentiodynamic polarization (PDP) analysis, (D) shows corrosion parameters obtained from PDP, (E) shows corrosion inhibition mechanism, (F) shows SEM image, (G) shows XPS analysis, and (H) shows AFM image.

[0032] FIG. 4 shows the performance measurement criteria of the flow-type and gel-type Al-EES according to one embodiment of the present invention, and specifically, (A) shows a schematic diagram of the Al-EES flow-type system, (B) compares the voltage-power density of the flow-type Al-EES with that of other existing flow-type devices, (C) shows a polarization curve of the flow-type Al-EES, (D) shows an EIS spectrum of the flow-type Al-EES, (E) shows a discharge profile of the flow-type Al-EES according to various currents, (F) shows a polarization curve of the flow-type Al-EES with multiple stacks (three cells in series), (G) shows a discharge profile of the Al-EES stack at 1 W, and (H) shows a large stack (256 cm) consisting of four cells in series. 2 ) shows the polarization curve, (I) shows the schematic for gel-type Al-EES, (J) shows the polarization curve of gel-type Al-EES, and (K) shows the polarization curve of 1 mA / cm 2 The discharge profile of the gel-type Al-EES is shown in .

[0033] Figure 5 illustrates applications of Al-EES, specifically (A) a single cell powering a digital clock, (B) two cells powering LEDs, (C) two cells illuminating 50 LEDs, (D) a schematic for various applications of Al-EES, (E) an emergency lamp powered by gel-type Al-EES, (F) a compact car powered by Al-EES, and (G, H & I) an electric car operating using Al-EES.

[0034] In this specification, when a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless specifically stated otherwise.

[0035] In this specification, “A and / or B” means “A and B, or A or B.”

[0036] In this specification, when it is said that a component is “on”, this does not exclude other components being placed therebetween, unless otherwise specifically stated, but rather means that other components may be placed thereon.

[0037] Hereinafter, an embodiment of the present invention will be described in detail with reference to the attached drawings. The drawings may be exaggerated, omitted, or schematically illustrated to explain or emphasize the contents of an embodiment of the present invention.

[0038] FIG. 1 is a schematic diagram of an aluminum electrochemical energy system (Al-EES) according to one embodiment of the present invention.

[0039] Hereinafter, the present invention will be described in more detail.

[0040] One embodiment of the present invention comprises an electrolyte including a positive electrode; a negative electrode; and an anodic solution, wherein the anodic solution is S x O y An aluminum electrochemical energy cell comprising a salt or ion containing .

[0041] An aluminum electrochemical energy cell according to one embodiment of the present invention can reduce aluminum corrosion and improve cell performance without requiring a catalyst and a separator by including an electrolyte including an anode solution.

[0042] In an aluminum electrochemical energy cell according to one embodiment of the present invention, an oxidation reaction occurs at the cathode and a reduction reaction occurs at the anode, and the electrochemical reaction in the aluminum electrochemical energy cell is as follows.

[0043]

[0044] Cathode: 2Al → 2Al 3+ + 6 e , E˚ 1.6 V -----------(1)

[0045] Anode: 3S2O8+ 6 e → 6SO4 - , E˚ 2.1 V -----------(2)

[0046] Total: 2Al + 8NaOH + 3Na2S2O8→ 2NaAl(OH)4+ 6Na2SO4, E˚cell=3.7 V (3)

[0047]

[0048] An aluminum electrochemical energy cell according to one embodiment of the present invention has a high energy density, allowing for long-term use and can be used in various electronic products. Furthermore, the aluminum electrochemical energy cell can be configured as a battery module comprising a plurality of groups of unit cells, and the manufactured electric module can be specifically used as a power source for electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, or power storage devices, and can also be used for mounting or detaching.

[0049] Figures 2 (A) and (B) show schematic diagrams of a conventional Al-air and an Al-EES according to an embodiment of the present invention.

[0050] According to (A) and (B) of the above Figure 2, considering the high binding energy of oxygen (498 kJ / mol), oxygen reduction requires multiple steps and a highly active catalyst such as Pt. In contrast, persulfate can be easily reduced because its binding energy is only about 140 kJ / mol, and it requires about 3.5 times less energy than oxygen to break the bond, so reduction can easily occur even without a catalyst.

[0051] According to one embodiment of the present invention, the anode may not contain a catalyst. As described above, the anode does not contain a catalyst, thereby enabling the implementation of an aluminum electrochemical energy cell capable of reduction even with a small amount of energy.

[0052] According to one embodiment of the present invention, the Sx O y It may be at least one selected from the group consisting of S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, SO5 and combinations thereof. In the above range, the S x O y By selecting , an aluminum electrochemical energy cell capable of reduction with little energy without a catalyst can be realized.

[0053] According to one embodiment of the present invention, the S x O y Silver persulfate (Na2S2O8) or persulfate ion (S2O8 2- ) may be. As described above, the S x O y Silver persulfate (Na2S2O8) or persulfate ion (S2O8 2- ) can be used to implement an aluminum electrochemical energy cell capable of reduction with little energy without a catalyst.

[0054] According to one embodiment of the present invention, the electrolyte may be at least one selected from the group consisting of sodium hydroxide, sodium chloride, potassium chloride, potassium hydroxide, and the like. By selecting the electrolyte within the above-described range, a battery reaction can be performed with a high ionization tendency.

[0055] According to one embodiment of the present invention, the concentration of the positive electrode solution may be 0.1 M or more and 2.0 M or less. Specifically, the concentration of the positive electrode solution may be 0.1 M or more and 2.0 M or less, 0.3 M or more and 1.9 M or less, 0.5 M or more and 1.8 M or less, 0.7 M or more and 1.7 M or less, 0.9 M or more and 1.6 M or less, 1.0 M or more and 1.6 M or less, 1.1 M or more and 1.6 M or less, 1.2 M or more and 1.6 M or less, 1.3 M or more and 1.6 M or less, or 1.4 M or more and 1.6 M or less. By controlling the concentration of the positive electrode solution within the above-described range, the battery performance through the current density and power density of the aluminum electrochemical energy battery can be improved.

[0056] According to one embodiment of the present invention, the concentration of the electrolyte may be 0.5 M or more and 5.0 M or less. Specifically, the concentration of the electrolyte may be 0.7 M or more and 4.8 M or less, 0.9 M or more and 4.6 M or less, 1.0 M or more and 4.4 M or less, 1.2 M or more and 4.2 M or less, 1.4 M or more and 4.0 M or less, 1.6 M or more and 3.8 M or less, 1.8 M or more and 3.6 M or less, 2.0 M or more and 3.4 M or less, 2.2 M or more and 3.2 M or less, 2.4 M or more and 3.2 M or less, 2.6 M or more and 3.2 M or less, 2.8 M or more and 3.2 M or less, or 2.9 M or more and 3.1 M or less. By controlling the concentration of the electrolyte within the above-described range, the battery performance through current density and power density of the aluminum electrochemical energy cell can be improved.

[0057] According to one embodiment of the present invention, the concentration ratio of the positive electrode solution and the electrolyte may be 1:0.5 or more and 3:1 or less. Specifically, the concentration ratio of the positive electrode solution and the electrolyte may be 1:0.7 or more and 3:1 or less, 1:0.9 or more and 3:1 or less, 1:1 or more and 3:1 or less, 1.2:1 or more and 2.8:1 or less, 1.4:1 or more and 2.6:1 or less, 1.6:1 or more and 2.4:1 or less, 1.8:1 or more and 2.2:1 or less, or 1.9:1 or more and 2.1:1 or less. By controlling the concentration ratio of the positive electrode solution and the electrolyte within the above-described range, the battery performance through the current density and power density of the aluminum electrochemical energy battery can be improved.

[0058] According to one embodiment of the present invention, the cathode may comprise aluminum. Specifically, the cathode is an electrode that loses electrons and oxidizes aluminum. The cathode may comprise aluminum and may be manufactured in the form of an aluminum sheet, an aluminum alloy, or the like.

[0059] According to one embodiment of the present invention, the anode may include at least one selected from the group consisting of carbon cloth (CC), carbon felt (CF), nickel foam (NF), graphite, and stainless steel (SS). Preferably, the anode may include carbon, and more preferably, it may be carbon cloth (CC).

[0060] According to one embodiment of the present invention, the content of the positive electrode solution may be 10 wt% or more and less than 50 wt% based on the total weight of the electrolyte. Preferably, the content of the positive electrode solution may be 10 wt% or more and less than 40 wt% based on the total weight of the electrolyte, and more preferably 20 wt% or more and less than 35 wt%. If it is less than the above-mentioned range, the corrosion prevention effect and the improvement in energy density of the aluminum electrochemical energy cell may be minimal, and if it exceeds the above-mentioned range, side reactions other than the desired reaction may occur, which may actually lower the energy density.

[0061] According to one embodiment of the present invention, the electrolyte may be in a static, fluid, or gel form. In the case of the static form, the same as described above is applied.

[0062] According to one embodiment of the present invention, unlike conventional ion-permeable selective membranes, the flow-type battery can separate electrodes through laminar flow of electrolyte. Furthermore, the two pumps and valves found in conventional flow batteries can be replaced with a single flow. Consequently, the battery offers higher reliability than conventional flow batteries, making it particularly suitable for large-scale applications.

[0063] According to one embodiment of the present invention, the aluminum electrochemical energy cell can generate power ranging from milliwatts to several watts. Furthermore, it demonstrates the feasibility of a stable and robust energy conversion device, and can also generate approximately 2,650 Wh / kg. Al It can realize remarkable energy density. Furthermore, it has economic advantages because it does not require expensive catalysts or membranes.

[0064] Hereinafter, the present invention will be described in detail using examples. However, the examples according to the present invention may be modified in various ways, and the scope of the present invention is not limited to the examples described below. The examples in this specification are provided to more fully explain the present invention to those of ordinary skill in the art.

[0065] <Manufacturing Example>

[0066] 1. Static Al-EES type manufacturing

[0067] Commercial-grade aluminum sheet and carbon cloth (CC) are cut into 1 × 5 cm pieces and placed in a 2:1 ratio of anolyte and electrolyte mixture, maintaining a distance of 1 cm. The active area of ​​Al and carbon in the solution is approximately 1 × 1 cm. 2 . In addition, the total volume of the electrolyte and anolyte mixture is 100 ml. At this time, NaOH is the electrolyte and Na2SO2O8 is the anolyte.

[0068]

[0069] 2. Manufacturing of fluid AL-EES

[0070] Flow channel plates are made by processing commercial-grade acrylic sheets, each 1 cm thick, to the required length and width. Teflon connectors are installed at the inlet and outlet of the plates to facilitate flow. The cell is assembled using aluminum plates and carbon cloth (CC) located on both sides of the flow plate. On the cathode side, a graphite plate is used to support the CC, and a copper current collector is placed next to the graphite plate to capture the output. The inlet and outlet of the flow plate are connected to a reservoir equipped with a circulation pump. The total volume of the electrolyte and anolyte mixture is 1.5 L.

[0071]

[0072] 3. Manufacturing of gel-type Al-EES

[0073] Poly(sodium acrylate) hydrogels are synthesized via free radical polymerization of acrylic acid using ammonium persulfate (APS) as the initiator. Acrylic acid (1.00 eq) is partially neutralized by dropwise addition of NaOH solution (0.75 eq). Polymerization is performed at room temperature under a nitrogen atmosphere with a 25 wt% aqueous solution using APS as the radical redox initiator. Gelation typically occurs within 1 hour, and polymerization proceeds overnight. The resulting hydrogel is cut into small pieces, completely neutralized with aqueous NaOH solution, and then immersed in excess water to remove any residual unreacted chemicals. The pieces are then dried overnight in a vacuum oven at 70°C. The dried material is then immersed in a mixture of anolyte and electrolyte (3 M NaOH + 1.5 M Na2S2O8). The gel is immersed in this mixture for 4 hours, after which the device is assembled by sandwiching the aluminum foil and CC between the saturated membranes.

[0074]

[0075] <Example>

[0076] Examples 1 to 3

[0077] In the static Al-EES type manufactured from the above manufacturing example 1, the concentrations of the electrolyte and the anodic solution were controlled as follows.

[0078] Sodium hydroxide molar concentration (M) Persulfate molar concentration (M) Example 1 10.5 Example 2 21 Example 3 31.5

[0079] Examples 4 to 7 In the static Al-EES type manufactured from the above Manufacturing Example 1, instead of carbon cloth (CC), various anodes were manufactured, including carbon felt (CF) (Example 4), nickel foam (NF) (Example 5), graphite (Example 6), and stainless steel (SS) (Example 7).

[0080]

[0081] Comparative Examples 1 to 3

[0082] In the static Al-EES type manufactured from the above manufacturing example 1, the concentrations of the electrolyte and the anodic solution were controlled as follows.

[0083]

[0084] Sodium hydroxide molar concentration (M) Persulfate molar concentration (M) Comparative example 110 Comparative example 220 Comparative example 330

[0085] <Experimental Example>1.1 Hydrogen Generation Test

[0086] Hydrogen gas evolution tests were performed by collecting hydrogen in a burette equipped with a gas guide. Aluminum (1 x 1 cm 2 ) was exposed to various solutions containing NaOH and sodium persulfate, the amount of hydrogen produced was measured by taking readings every 5 minutes using the exhaust gas collection method. The self-corrosion rate (S) and suppression efficiency (θ) of hydrogen evolution were calculated as follows.

[0087]

[0088] In this formula, VH2 represents the amount of hydrogen gas produced, and A represents the exposed area (cm 2 ) and T represents the immersion time (seconds). S NaOH and S NaOH + Na2S2O8 represent the self-corrosion rates of the samples in the absence and presence of sodium persulfate, respectively.

[0089]

[0090] 1.2. Surface Characterization

[0091] 1 x 1 cm each 2 Aluminum sheet specimens of various sizes were polished using abrasive paper and then washed with deionized water and ethanol. After drying in an oven, the specimens were immersed in various solutions for 30 min. The surface morphology, which reflects the corrosion behavior of Al, was examined using a scanning electron microscope (SEM) (JXA-8530 Plus; JEOL). Similarly, the surface roughness was evaluated using a nano-profiler and atomic force microscopy (AFM).

[0092]

[0093] 1.3. Electrochemical measurements

[0094] Electrochemical measurements were performed using an electrochemical workstation (AUTOLAB; VIONIC) equipped with a three-electrode system. 1 x 1 cm 2 Al pieces were used as working electrodes, and Ag / AgCl and Pt foils (1 x 1 cm 2 ) were used as the reference and counter electrodes, respectively. Potentiodynamic polarization tests were performed under various electrolyte and anolyte compositions. To achieve a steady-state potential before testing, each sample was immersed in the solution for 0.5 h without an external potential. Potential sweeps from 0 to 2 V were performed, and Tafel plots were generated for each test to calculate the corrosion rate and Tafel parameters. EIS measurements were performed at open circuit potential (OCP) using a frequency scanning from 106 to 0.1 Hz with an amplitude of 10 mV. EIS data were processed and fitted using Zview software.

[0095]

[0096] Performance Evaluation of a Static Al-EES System

[0097] Figure 2(c) shows the polarization curves of Al-EES, Al-air, and Al-H2O2 systems, the latter two systems using Pt / C as a cathode. According to this, Al-EES has an operating voltage (2 V), a limiting current density (520 mA cm -2 ) and power density (260 mWcm -2 ) It can be seen that the performance is superior to that of oxygen-based systems and H2O2-based systems.

[0098] Figure 2(D) shows the values ​​corresponding to the Al-EES polarization and power density curves for various NaOH / Na2S2O8 compositions. According to this, it can be confirmed that both the NaOH concentration and the Na2S2O8 concentration significantly affect the current density and power density of the Al-EES system, and the maximum performance is achieved with the composition of 3 M NaOH + 1.5 M Na2S2O8 in Example 3.

[0099] Figure 2 (G) shows values ​​corresponding to the polarization curves of various cathodes, including carbon cloth (CC), carbon felt (CF), nickel foam (NF), graphite, and stainless steel (SS), corresponding to Examples 3 to 7. According to this, it can be seen that carbon cloth (CC) of Example 3 obtained the highest output due to its hydrophilic properties, whereas stainless steel (SS) of Example 7 showed the lowest output.

[0100]

[0101] Corrosion resistance evaluation

[0102] Figure 3 shows a corrosion study of Al, and specifically, (A) shows a hydrogen evolution test analyzed by a drainage method using electrolytes and anolytes of different concentrations, and shows the hydrogen evolution rate (RH2) and corrosion inhibition efficiency (IEn) of Al between various concentrations.

[0103] According to (A) of the above drawing 3, it can be seen that the RH2 between pure NaOH and Al anode is very high (according to Equation 1 below).

[0104]

[0105] [Formula 1]

[0106] 2Al + 3H2O → Al2O3+ 3H2

[0107]

[0108] In contrast, the introduction of Na2S2O8 causes RH2 to A significant decrease is observed, which is mainly due to the interaction between the Na2S2O8 molecules and the Al surface. This interaction, facilitated by the unshared electron pair of the oxygen atoms present in Na2S2O8, forms a protective film that acts as a barrier, preventing direct contact of H2O molecules and thus promoting oxidation by avoiding HER (according to Eq. 2 below).

[0109]

[0110] [Formula 2]

[0111] Al + 4OH - → Al(OH)4 - + 3e - → Al(OH)3+ OH -

[0112]

[0113] Figure 3 (c) shows the potential difference polarization (PDP) analysis. Specifically, the corrosion current density (i corr ), corrosion potential (E corr ) can represent electrochemical parameters and corrosion rates such as corrosion current density i. corr (mA / cm - 2 ) The lower the value, the better the corrosion resistance.

[0114]

[0115]

[0116]

[0117] According to Table 3 above, the corrosion resistance gradually decreased from Comparative Example 1 to 3, and from Practice 1 to 3, i corr (mA / cm - 2 ) values ​​decrease, indicating that corrosion resistance increases. In addition, it can be seen that the corrosion rate also decreases from Example 1 to Example 3 compared to the comparative example.

[0118] In addition, according to (D) of Fig. 3, it can be seen that the above Example 3 has improved corrosion resistance. As a result, Na2S2O8 It can be seen that it functions as a mixed inhibitor for Al corrosion.

[0119] According to (F) of Fig. 3, in the absence of Na2S2O8 in the electrolyte, the Al surface is significantly corroded and damaged. (i) shows that the intense localized HER reaction causes non-uniform dissolution of Al, resulting in numerous cracks and pits of varying depth on the metal surface, while (ii) shows that Na2S2O8 substantially modifies the surface properties of Al, resulting in a smoother metal surface.

[0120] Figure 3 (H) shows the corrosion of Al in 3M NaOH with and without Na2S2O8 using atomic force microscopy (AFM). The differences in surface topography were compared. The image on the left shows that Al's topography is rough, with deep holes and sharp protrusions, resulting in S max and Ra are measured to be quite high, with values ​​of 1,900 nm and 186 nm, respectively. In contrast, the image on the right shows that the Al surface is smoother and S max and Ra are measured to be approximately 1,263 and 135 nm, respectively.

[0121]

[0122] Performance Evaluation of Fluid-Type and Gel-Type Al-EES Systems

[0123] Figure 4 (A) shows a schematic diagram of an Al-EES fluid system.

[0124] Figure 4(B) compares the voltage-power density of the flow-type Al-EES with that of other existing flow-type devices. This shows that the Al-EES outperforms established technologies such as vanadium flow batteries and zinc bromide batteries in terms of power density and voltage.

[0125] Meanwhile, Fig. 4 (I) shows a schematic diagram of gel-type Al-EES.

[0126] Figure 4 (J) shows the polarization curve of the gel-type Al-EES. According to this, the Al-air system (21 mWcm) using Pt / C as a cathode -2 ) exceeding 24mWcm -2 It represents the power density of .

[0127] Also, (K) in Fig. 4 is 1 mA / cm 2 The discharge profile of the gel-type Al-EES is shown in . According to this, it can be seen that it exhibits higher discharge time and voltage than the Al-air system.

[0128]

[0129]

[0130] According to Table 4 above, the gel-based Al-EES outperforms previously reported air-based systems and other flexible devices.

[0131]

[0132] Therefore, an aluminum electrochemical energy cell according to one embodiment of the present invention can reduce aluminum corrosion and improve cell performance without requiring a catalyst and a separator by specifically including an electrolyte including an anode solution.

[0133]

[0134] The present invention can improve cell performance without requiring a catalyst and a separator by including an electrolyte including a positive electrode solution.

Claims

1. Containing an electrolyte including a positive electrode; a negative electrode; and a positive electrode solution; The above positive electrode solution is S x O y An aluminum electrochemical energy cell comprising a salt or ion.

2. In claim 1, S above x O y An aluminum electrochemical energy cell, wherein the aluminum electrochemical energy cell comprises at least one selected from the group consisting of S4O6, S3O6, S2O3, S2O4, S2O5, S2O6, S2O7, S2O8, SO4, SO5 and combinations thereof.

3. In claim 2, S above x O y Silver persulfate (Na2S2O8) or persulfate ion (S2O8 2- ) is an aluminum electrochemical energy cell.

4. In claim 1, An aluminum electrochemical energy cell, wherein the electrolyte is at least one selected from the group consisting of sodium hydroxide, sodium chloride, potassium chloride, potassium hydroxide, and the like.

5. In claim 1, An aluminum electrochemical energy cell, wherein the concentration of the positive electrode solution is 0.1 M or more and 2.0 M or less.

6. In claim 1, An aluminum electrochemical energy cell, wherein the concentration of the electrolyte is 0.5 M or more and 5.0 M or less.

7. In claim 1, An aluminum electrochemical energy cell, wherein the concentration ratio of the positive electrode solution and the electrolyte solution is 1:0.5 or more and 3:1 or less.

8. In claim 1, An aluminum electrochemical energy cell, wherein the cathode comprises aluminum.

9. In claim 1, An aluminum electrochemical energy cell, wherein the positive electrode comprises at least one selected from the group consisting of carbon cloth (CC), carbon felt (CF), nickel foam (NF), graphite, and stainless steel (SS).

10. In claim 1, An aluminum electrochemical energy cell wherein the anode does not contain a catalyst.

11. In claim 1, An aluminum electrochemical energy cell, wherein the content of the positive electrode solution is 10 wt% or more and less than 50 wt% of the total weight of the electrolyte.

12. In claim 1, An aluminum electrochemical energy cell, wherein the electrolyte is in a static, fluid or gel form.

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