Magnesium secondary battery and method for manufacturing a magnesium secondary battery

Abstract

To provide a magnesium secondary battery and a method for manufacturing a magnesium secondary battery that can suppress the formation of a passivation film even when magnesium metal is used as the negative electrode, thereby improving reproducibility and safety. [Solution] The device comprises a positive electrode having vanadium oxide (V2O5) or molybdenum oxide (MoO3) that has been nanostructured by mixing conductive carbon nanotubes, a negative electrode having a nanostructured magnesium-aluminum alloy (Mg-Al alloy) and a magnesium-graphene composite material in a nanosheet structure obtained by compounding graphene and magnesium in a solution process, and a water-soluble electrolyte containing nanoparticles disposed between the positive electrode and the negative electrode, wherein the positive electrode and the negative electrode are separated by a separator, and a nanobarrier film made of a porous polymer nanomembrane for suppressing passivation is sandwiched between the separator and the negative electrode.

Description

[Technical Field]

[0001] This invention relates to a magnesium secondary battery and a method for manufacturing a magnesium secondary battery. [Background technology]

[0002] In recent years, the demand for lithium-ion rechargeable batteries has been increasing in applications such as smartphones, portable electronic devices, electric vehicles, hybrid electric vehicles, and even fixed energy storage systems.

[0003] However, current lithium-ion rechargeable batteries use flammable organic solvents as electrolytes, requiring robust casings to prevent leakage of these solvents. Furthermore, portable computers and other devices must incorporate structures that mitigate the risks associated with electrolyte leakage, thus imposing constraints on the device's design.

[0004] Furthermore, its applications are expanding to mobile devices such as automobiles and drones, and large capacities are required for fixed-installation lithium-ion secondary batteries.

[0005] On the other hand, safety is becoming increasingly important, and efforts are being made to develop lithium-ion secondary batteries that do not use harmful substances such as organic solvents.

[0006] In recent years, next-generation rechargeable batteries have attracted attention as a key device for realizing a low-carbon society, and their application in a wider range of uses than before is being considered from the perspective of efficient energy utilization.

[0007] There is a growing demand for rechargeable batteries that offer higher capacity and lower cost than lithium-ion batteries, and research and development of various types of rechargeable batteries is active. Research and development is underway on magnesium-ion rechargeable batteries, one of the next-generation rechargeable batteries, which use divalent (multivalent) cations. Magnesium, a group 2 element, is a promising electrode material due to its physical properties, but it has challenges that need to be overcome before it can be put into practical use.

[0008] When considered as a multivalent ion battery, magnesium ions exhibit strong solvation, making intercalation reactions impossible with a carbon anode. Furthermore, very few materials capable of inserting and deinserting magnesium ions at low potentials suitable for use as a negative electrode have been discovered. However, since dendrites are not formed, a magnesium metal dissolution and extraction reaction can be employed. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 5617131 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, when magnesium metal is used as the negative electrode, a passive film is formed during charging and discharging. Since this passive film on the magnesium surface has neither ionic nor electronic conductivity, it inhibits the dissolution and extraction reaction, posing a challenge. Therefore, an electrolyte that enables the dissolution and extraction of magnesium is needed. While Patent Document 1 discloses the electrolyte for a magnesium secondary battery and a method for manufacturing that electrolyte, it does not take into account the overall performance of the magnesium secondary battery and is therefore insufficient.

[0011] This invention was devised in view of the above-mentioned background, and its objective is to provide a magnesium secondary battery and a method for manufacturing a magnesium secondary battery that can suppress the formation of a passivation film even when magnesium metal is used as the negative electrode, thereby improving reproducibility and safety. [Means for solving the problem]

[0012] The magnesium secondary battery according to the first invention includes a positive electrode having vanadium oxide (V2O5) or molybdenum oxide (MoO3) that is nano-structured by mixing conductive carbon nanotubes, a nano-structured magnesium-aluminum alloy (Mg-Al alloy), and a magnesium-graphene composite material with a nanosheet structure in which graphene and magnesium are combined by a solution process, a negative electrode, and a water-soluble electrolyte disposed between the positive electrode and the negative electrode and containing nanoparticles. The positive electrode and the negative electrode are separated by a separator.

[0013] The magnesium secondary battery according to the second invention is characterized in that, in the first invention, a nanofilm for passivation film suppression made of a polymer nanofilm with a porous structure is sandwiched between the separator and the negative electrode.

[0014] The method for manufacturing a magnesium secondary battery according to the third invention is the method for manufacturing the magnesium secondary battery of the second invention, and includes a raw material preparation step of preparing raw materials for the positive electrode and the negative electrode, a slurry preparation and electrode coating step of separately performing a slurry preparation and coating process on the positive electrode material and the negative electrode material created by the raw material preparation step, an electrolyte preparation step of adjusting the pH of distilled water added with NaOH or KOH and uniformly dispersing silver nanoparticles to create a water-soluble electrolyte, and a separator preparation step of creating a nanoporous separator.

Effect of the Invention

[0015] According to the present invention having the above-described configuration, it is possible to suppress the passivation film even when magnesium metal is used for the negative electrode, and to realize a magnesium secondary battery and a method for manufacturing a magnesium secondary battery with improved high reproducibility and safety.

Brief Description of the Drawings

[0016] The drawings show specific embodiments of the present invention and include not only essential components of the invention but also optional and preferred embodiments. [Figure 1]A diagram for explaining the basic operating principle of the magnesium secondary battery of the present invention. [Figure 2] A schematic diagram of the magnesium secondary battery according to the present invention. [Figure 3] (a) A diagram for explaining the problems of the present invention, (b) A diagram for explaining the effect of suppressing the formation of an inert film by the magnesium secondary battery according to the present invention. [Figure 4] A diagram showing an example of the cathode (positive electrode), anode (negative electrode), particle size, concentration, and mixing ratio of the magnesium secondary battery according to the present invention. [Figure 5] A diagram showing an example of the thickness, pore size, concentration, cathode (positive electrode), anode (negative electrode), and mixing ratio of the separator (polymer nanoporous separator) of the magnesium secondary battery according to the present invention. [Figure 6] A diagram showing an example of the component ratio of the electrolyte of the magnesium secondary battery according to the present invention. [Figure 7] A manufacturing process diagram of the magnesium secondary battery according to the present invention. [Figure 8] A diagram showing an example of the mixing ratio and concentration of the electrolyte of the magnesium secondary battery according to the present invention.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments exemplified by applying the present invention will be described with reference to the drawings.

[0018] <Embodiment 1> FIG. 1 is an explanatory diagram of the operating principle of a magnesium secondary battery (ion battery). In the example of FIG. 1, a schematic example of a polyvalent ion battery using divalent magnesium cations is shown, and the specific configuration is omitted.

[0019] As shown in Figure 1, the magnesium secondary battery 1 comprises a positive electrode (cathode) 2, a negative electrode (anode) 3, a separator 4, an electrolyte 5, and a positive electrode current collector 7. By connecting a load or power source 6, it can be repeatedly used for charging (storing electricity) and discharging (using electricity) through the dissolution and discharge reaction of magnesium metal from the negative electrode (anode) 3. In Figure 1, the negative electrode current collector is omitted.

[0020] The negative electrode 3 is characterized by the inclusion of a nanobarrier film 8 (see Figure 2), which has a particularly effective effect in suppressing the formation of a passive film, as a passive film would form if it were composed solely of magnesium metal. In addition, high reproducibility and safety can be achieved by nanostructuring both the positive electrode 2 and the negative electrode 3.

[0021] The magnesium secondary battery of this embodiment, in particular to solve the problems of the passivation film of the present invention, is characterized by having a positive electrode 2 having vanadium oxide (V2O5) or molybdenum oxide (MoO3) that is nanostructured by mixing conductive carbon nanotubes, as shown in Figure 2; a negative electrode 3 having a nanostructured magnesium-aluminum alloy (Mg-Al alloy) and a magnesium-graphene composite material in a nanosheet structure obtained by compounding graphene and magnesium in a solution process; and a water-soluble electrolyte 5 containing nanoparticles, which is disposed between the positive electrode 2 and the negative electrode 3, and the positive electrode 2 and the negative electrode 3 are separated by a separator 4.

[0022] A nanobarrier film 8, made of a porous polymer nanofilm, is sandwiched between the separator 4 and the negative electrode 3 to suppress the formation of a passivation film. This nanobarrier film 8 provides a passivation film suppression effect.

[0023] In other words, as shown in Figure 3(a), if the negative electrode 3 is made of magnesium metal alone, a passivation film P forms, which inhibits the magnesium dissolution reaction. In contrast, as shown in Figure 3(b), a nanobarrier film 8 is provided between the negative electrode 3 and the electrolyte 5, so the passivation film can be suppressed. The configuration of the magnesium secondary battery of this embodiment will be described below.

[0024] <Selection and manufacturing process of positive electrode material (cathode)> <Material> Nanostructured vanadium oxide (V2O5) or molybdenum oxide (MoO3), conductive carbon nanotubes (CNTs)

[0025] <Manufacturing Process> In the manufacturing process of this embodiment, first, V2O5 nanoparticles are synthesized by a solution process, and then their crystal structure is optimized by high-temperature firing (600°C). An appropriate amount of CNTs is mixed in to form a slurry, which is then applied to an aluminum substrate. After drying, additional firing is performed at a low temperature (200°C).

[0026] Here, the nano-sized cathode material achieves high energy density by effectively intercalating magnesium ions and increasing the reaction area.

[0027] <Scientific evidence> In this embodiment, V2O5 and MoO3 are suitable for the insertion and removal of magnesium ions, and their surface area is increased by forming them into nanoparticles, thereby improving the reaction rate.

[0028] <Selection and manufacturing process of negative electrode material (anode)> <Material> In this embodiment, magnesium-aluminum alloy (Mg-Al alloy) and magnesium-graphene composite material are used as nanostructured magnesium alloys.

[0029] <Manufacturing Process> In the first step, the magnesium-aluminum alloy is reduced to a nano-sized powder and subjected to surface treatment using a laser ablation method to suppress the formation of a passivation film. Next, in the second step, graphene and magnesium are compounded using a solution process to form a nanosheet structure. This enhances conductivity and improves the efficiency of charge-discharge cycles.

[0030] <Scientific evidence> In this embodiment, magnesium alloys and graphene possess excellent electrical and ionic conductivity, and by suppressing the formation of a magnesium passivation film, a longer lifespan can be achieved.

[0031] <Selection and manufacturing process of electrolytes> <Material> In this embodiment, a water-soluble electrolyte material containing silver nanoparticles (for example, an alkaline electrolyte adjusted to pH 8-9) is used.

[0032] <Manufacturing Process> In this embodiment, the following steps 1 to 3 are performed. First, as the first step, an alkaline aqueous solution adjusted to pH 8-9 is selected as the basic electrolyte.

[0033] Next, in the second step, silver nanoparticles are uniformly dispersed in the solution to improve the conductivity and safety of the electrolyte. Next, as a third step, the reaction between the magnesium electrode and the electrolyte is optimized by using a high-purity electrolyte.

[0034] <Scientific evidence> In this embodiment, by performing the second step, the silver nanoparticles improve the conductivity of the electrolyte and simultaneously promote ion transfer. Furthermore, by adjusting the pH of the electrolyte, the reactivity with the electrode material can be controlled and degradation can be prevented.

[0035] <Design of separators and barrier films> <Material> In this embodiment, a separator (polymer nanofilm) using barrier film technology is employed as the material.

[0036] <Manufacturing Process> In this embodiment, as the first step, a polymer nanofilm is sandwiched between the electrolyte and the negative electrode to suppress the formation of a passivation film while ensuring ionic conductivity. Next, in the second step, patented technology is used to give the barrier film a nano-sized porous structure.

[0037] <Scientific evidence> Here, the nanofilm does not hinder the movement of magnesium ions while simultaneously improving the lifespan of the separator. Barrier film technology prevents the permeation of oxygen and moisture, thereby suppressing degradation.

[0038] <Safety and suppression of passivation film formation through nanotechnology> In this embodiment, we demonstrate a safe and high-energy-density magnesium battery by utilizing nanotechnology and a coating technique that fundamentally prevents the formation of a passivation film.

[0039] <Additional technologies> In this process, a nanocoating is applied to the electrode surface to prevent the initiation of passivation film formation. This will enable the development of surface protection films using self-healing nanomaterials, thereby extending battery life.

[0040] <Scientific evidence> Here, nanocoating minimizes the oxidation reaction of the magnesium electrode and maximizes ion transfer efficiency. Furthermore, self-healing materials rapidly repair minor damage, dramatically extending cycle life.

[0041] <According to this demonstration> This magnesium secondary battery manufacturing method utilizes nanotechnology and advanced materials to achieve both high energy density and safety.

[0042] The following details the specific raw materials, concentrations, formulations, and particle sizes for each component of a magnesium secondary battery (positive electrode, negative electrode, separator, and electrolyte), and presents a method for creating formulations that emphasizes scientific basis and reproducibility. Figure 4 shows the raw materials, particle sizes, concentrations, and formulation ratios for the positive and negative electrodes. The following explanation of how to create the positive and negative electrodes will use Figure 4.

[0043] <Method of Making the Positive Electrode (Cathode)> <Materials> In this embodiment, vanadium oxide (V2O5) nanoparticles are prepared as the material. Here, the particle size is set to 50 nm, the concentration is set to 80 wt% (weight percent), and a blending ratio of 80 g (per 100 g of the positive electrode material) is adopted. Also, in this embodiment, carbon nanotubes (CNTs) with a particle size of 20 nm are adopted as the conductive carbon nanotubes. Here, the concentration of the carbon nanotubes is set to 10 wt%, and the blending ratio is set to 10 g (per 100 g of the positive electrode material). Also, in this embodiment, the concentration of the binder (PVDF: polyvinylidene fluoride) is set to 10 wt%, and the blending ratio is set to 10 g (per 100 g of the positive electrode material).

[0044] <Process> <Synthesis of V2O5 Nanoparticles> In this embodiment, as Process 1, the hydrothermal synthesis method is used to generate nanoparticles with a size of 50 nm, and the crystal structure is adjusted by high-temperature firing (600 °C).

[0045] <Mixing of CNTs> In this embodiment, as Process 2, CNTs are mixed with the V2O5 nanoparticles to form a slurry, and a PVD binder is added, and the slurry is coated on an aluminum foil.

[0046] <Drying and Firing> In this embodiment, as Process 3, after drying the coated slurry, additional low-temperature firing is performed at 200 °C to enhance the conductivity and stability as an electrode.

[0047] <Scientific Basis> Here, vanadium oxide is suitable for the intercalation and deintercalation of magnesium ions, and the reaction area increases by nanosizing. CNTs significantly improve the conductivity and reduce the internal resistance during charge and discharge.

[0048] <Method of Making the Negative Electrode (Anode)> <Material> In this embodiment, as the material, a magnesium-aluminum alloy (Mg-Al alloy) is adopted, with a particle size of 500 nm, a concentration of 90 wt%, and a blending ratio of 90 g (in 100 g of the negative electrode material). In this embodiment, as the material, the graphene sheet has a structure of 10 layers as the particle size, a concentration of 5 wt%, and a blending ratio of 5 g (in 100 g of the negative electrode material). Also, in this embodiment, as the material, the binder (CMC: carboxymethyl cellulose) has a concentration of 5 wt% and a blending ratio of 5 g (in 100 g of the negative electrode material).

[0049] <Process> <Powdering of the Mg-Al Alloy> In this embodiment, as Process 1, after alloying by the melting method, it is pulverized to 500 nm with a ball mill.

[0050] <Graphene Composite> In this embodiment, as Process 2, the graphene sheet and the Mg-Al alloy are mixed by a solution process to create a uniform negative electrode material.

[0051] <Electrode Formation> In this embodiment, for the electrode formation, a CMC binder is added, coated as a slurry on a copper foil, and fired at 100 °C after drying.

[0052] <Scientific Basis> Here, the Mg-Al alloy suppresses the formation of the passive film and improves ion conduction. Graphene has excellent conductivity and extends the life of the electrode. CMC maintains the stability of the electrode and plays a role in suppressing expansion and contraction.

[0053] <Method of Making the Separator> <Material> In this embodiment, as the material, a polymer nanocomposite separator (PEEK: polyether ether ketone-based) is adopted, with a thickness of 25 μm, a pore size of 50 nm, a concentration of 100 wt%, and a mixing ratio of 1 sheet (per cell). The component ratio of this separator is shown in FIG. 5.

[0054] <Process> <Synthesis of PEEK film> In this embodiment, as Process 1, a porous film of PEEK is created by a thermal decomposition method to achieve a pore size of 50 nm.

[0055] <Surface treatment> In this embodiment, as Process 2, an antioxidant coating is applied to the surface of the separator to prevent the permeation of oxygen and moisture.

[0056] <Scientific basis> Here, the nanoporous separator can prevent the intrusion of oxygen and moisture while not hindering the movement of magnesium ions and maintaining the ionic conductivity. In addition, the porous film of PEEK has high heat resistance and mechanical strength, enabling long life.

[0057] <Method of making electrolyte> In this embodiment, the electrolyte adopts an alkaline aqueous solution (pH 8 - 9) and silver nanoparticles. The component ratio of this electrolyte is shown in FIG. 6. <00002八十九><0000二九〇><Material> In this embodiment, as the material, an alkaline aqueous solution (pH 8 - 9) is adopted, with water at 99 wt%, a concentration regulator (NaOH or KOH) at 1 wt%, and the pH is adjusted to pH 8 - 9. Similarly, the particle size of the silver nanoparticles is 10 nm, the concentration is 0.05 wt%, and the mixing ratio is 50 mg / L.

[0059] <Process> <Preparation of alkaline aqueous solution> In this embodiment, as process 1, 1 wt% NaOH or KOH is added to high-purity water to adjust the pH to 8-9.

[0060] <Dispersion of silver nanoparticles> In this embodiment, as process 2, 10 nm sized silver nanoparticles are uniformly dispersed in a solution by ultrasonic dispersion.

[0061] <Scientific evidence> Here, the alkaline aqueous solution enables the stable movement of magnesium ions, and the silver nanoparticles improve the conductivity of the electrolyte. Silver promotes the redox reaction, thereby increasing the rate of ion movement and enabling efficient charging and discharging.

[0062] <Overall reproducibility and safety> <Reproducibility> In this embodiment, by strictly controlling the particle size and concentration of the nanomaterial, as well as the process temperature and time, in each step, it is possible to reproduce cells with identical performance.

[0063] <Safety> In this embodiment, the use of nanomaterials suppresses the formation of a passive film on the electrode surface, thereby preventing overheating and abnormal reactions. The heat resistance of the separator and the pH adjustment of the electrolyte ensure the long-term safety of the battery.

[0064] This formulation method enables the creation of a magnesium secondary battery manufacturing method that is based on scientific evidence from material selection to the manufacturing process, achieving high reproducibility and safety. Furthermore, by utilizing nanotechnology, it is possible to achieve efficient magnesium ion movement and high energy density.

[0065] <Second Embodiment> <Manufacturing method for magnesium secondary batteries> The manufacturing method for the magnesium secondary battery of the second embodiment is disclosed as shown in Figure 7, and is similar to the manufacturing method for the magnesium secondary battery described in the first embodiment. The manufacturing method for the magnesium secondary battery of the second embodiment will be described below.

[0066] <Raw material preparation process 501> <Preparation process of the positive electrode material> Hereinafter, the preparation process of the positive electrode material (vanadium oxide V2O5 and carbon nanotubes) will be described.

[0067] In this embodiment, a hydrothermal synthesis reactor, a high-temperature firing furnace, a ball mill, and a nanodisperser are prepared, and the preparation of the positive electrode material is carried out according to the following procedure.

[0068] <Procedure> <Synthesis of V2O5 nanoparticles> In this embodiment, as step 1, a hydrothermal synthesis reactor is used to create nanoparticles of vanadium oxide. Specifically, aiming for a particle size of 50 nm, the reaction temperature is 200 °C and a synthesis time of about 6 hours is required.

[0069] <High-temperature firing> In this embodiment, as step 2, the obtained nanoparticles are fired in a high-temperature firing furnace at 600 °C to optimize the crystal structure. Specifically, the firing time is about 3 hours.

[0070] <Preparation of carbon nanotubes> In this embodiment, as step 3, a ball mill or a nanodisperser is used to grind carbon nanotubes (CNT) to 20 nm or less and uniformly disperse them.

[0071] <Preparation process of the negative electrode material> Hereinafter, the preparation process of the negative electrode material (Mg-Al alloy and graphene) will be described.

[0072] In this embodiment, a melting furnace, a ball mill, a nanocomposite manufacturing device, and a solution process device are prepared, and the preparation of the negative electrode material is carried out. <Procedure> <Synthesis of Mg-Al alloy> In this embodiment, as step 1, magnesium and aluminum are alloyed at a high temperature in a melting furnace. The alloying temperature is 700°C, and the alloyed material is pulverized to a size of 500 nm using a ball mill.

[0073] <Preparing graphene> In this embodiment, as step 2, graphene and Mg-Al alloy are composited in a nanocomposite manufacturing apparatus and processed into a slurry. Next, a uniform composite is produced using a solution processing apparatus.

[0074] <Slurry preparation and application process 502> <Preparation of positive and negative electrode slurry> In this embodiment, a slurry mixer, a coater (coating machine), and a drying oven are prepared to create the slurry for the positive and negative electrodes.

[0075] <Instructions> <Slurry creation> In this embodiment, as step 1, the positive electrode material (V2O5 and CNT) and the negative electrode material (Mg-Al alloy and graphene) are mixed in separate slurry mixers, and a binder (PVDF or CMC) is added to form a slurry. Here, the positive electrode and negative electrode slurries are prepared independently.

[0076] <apply> In this embodiment, as step 2, a coater device is used to uniformly coat the slurry onto the aluminum foil for the positive electrode and the copper foil for the negative electrode. Here, the slurry thickness is approximately 10-20 μm.

[0077] <Drying> In this embodiment, step 3 involves applying the slurry and then drying it in a drying oven at a temperature of 100°C to improve the stability of the electrode material.

[0078] <Electrolyte preparation process 503> The following describes the electrolyte preparation process. In this embodiment, an ultrasonic dispersion device, a pH adjustment device, and a filter device are prepared, and the alkaline aqueous solution and silver nanoparticles are dispersed.

[0079] <Procedure> <pH adjustment> In this embodiment, as Step 1, NaOH or KOH is added to high-purity water, and the pH is adjusted to 8-9 using a pH adjustment device.

[0080] <Dispersion of silver nanoparticles> In this embodiment, as Step 2, an ultrasonic dispersion device is used to uniformly disperse silver nanoparticles. After dispersion, impurities are removed using a filter device.

[0081] <Preparation process 504 of separator> Hereinafter, the preparation process of the separator will be described. In this embodiment, machines such as a film extruder, a nanoporous generator, and a surface treatment device are prepared to create a PEEK nanoporous separator.

[0082] <Creation of PEEK nanoporous separator> <Procedure> <Film extrusion> In this embodiment, as Step 1, PEEK is extruded using a film extruder to create a film with a thickness of 25 μm.

[0083] <Porous formation> In this embodiment, as Step 2, a nanoporous generator is used to create a porous film with a pore size of 50 nm. The pore size is strictly controlled.

[0084] <Surface treatment> In this embodiment, as Step 3, an antioxidant coating is applied to the surface of the separator to prevent the intrusion of oxygen and moisture.

[0085] <Assembly process 505 of battery cell> Hereinafter, the assembly process of the battery cell will be described. In this embodiment, an automatic cell stacking machine, a vacuum sealing machine, and an assembly machine are prepared to stack and assemble the cells.

[0086] <Stacking and Assembly of Cells> <Procedure> <Stacking> In this embodiment, as Step 1, an automatic cell stacking machine is used to stack the positive electrode, separator, and negative electrode in sequence. Adjustments are made so that the positions of each layer overlap precisely during stacking.

[0087] <Electrolyte Injection> In this embodiment, as Step 2, an appropriate amount of electrolyte is injected into the assembled cell using an injection device.

[0088] <Sealing> In this embodiment, as Step 3, the cell is sealed with a vacuum sealing machine to prevent the intrusion of air and moisture from the outside.

[0089] <Inspection and Quality Control Process 506> The product inspection and quality control process will be described below. In this embodiment, a cycle test device, an X-ray inspection device, and a voltage / current measurement device are prepared, and the quality inspection of the battery will be described.

[0090] <Battery Quality Inspection> <Procedure> <Cycle Test> In this embodiment, as Step 1, a cycle test device is used to perform a charge / discharge cycle test to confirm the performance of the battery. It is confirmed that the cycle life of the magnesium secondary battery is sufficient.

[0091] <X-ray Inspection> In this embodiment, as Step 2, an X-ray inspection device is used to check whether there are any abnormalities in the internal structure and whether the stacking state is accurate.

[0092] <Measurement of Voltage / Current> In this embodiment, as Step 3, a voltage and current measurement device is used to measure the voltage, internal resistance, and current characteristics of each cell to confirm uniform performance.

[0093] <Optimization and Scale Expansion of the Manufacturing Line> <Improvement of Production Efficiency> <Automating the entire process> The following describes an example of establishing a mass production system using an automated slurry preparation system, automated coater, continuous drying oven, and automated assembly machine. This improves production speed while maintaining quality.

[0094] For selecting manufacturing equipment, automated equipment from precision machinery manufacturers such as Hitachi and Mitsubishi Heavy Industries is recommended. This is because high precision is required, especially for automatic stacking machines and vacuum sealing machines.

[0095] <Considerations based on the manufacturing process> <Preparation process for raw materials 501> In this embodiment, positive and negative electrode materials are prepared using hydrothermal synthesis or a nanocomposite production apparatus.

[0096] <Preparation of slurry and application to electrodes 502> In this embodiment, the slurry preparation and application to the electrode 502 are carried out by precise application using a slurry mixer and coating device, followed by drying.

[0097] <Electrolyte preparation process 503> In this embodiment, the electrolyte preparation step 503 involves pH adjustment and dispersion of silver nanoparticles using an ultrasonic dispersion device.

[0098] <Separator preparation process 504> In this embodiment, the separator preparation step 504 involves creating a PEEK separator using a nanoporous material generating apparatus.

[0099] <Battery cell assembly process 505> In this embodiment, the battery cell assembly process 505 involves stacking the cells using an automatic stacking machine and sealing them using a vacuum sealing machine.

[0100] <Quality Inspection Process 506> In this embodiment, the quality inspection process 506 involves performing inspections using a cycle test device and an X-ray inspection device to confirm uniform quality.

[0101] Each of the above processes can be made reproducible and stable by meticulously controlling each step. Especially when handling nano-sized materials, machine precision and process control are extremely important.

[0102] Specifically, we selected the optimal machine for manufacturing 3V and 150Ah prismatic cells, and the specific machine settings and part numbers are listed below. Each machine incorporates cutting-edge technology, selected to achieve both production efficiency and precision. Furthermore, the system is built around the ability to produce reproducible and high-quality cells.

[0103] <Manufacturing equipment used for the synthesis and preparation of positive electrode and negative electrode materials> <Configuration of the hydrothermal synthesis reactor> We will use a machine named Anton Paar Synthos 3000. Specifically, it will function as a hydrothermal synthesis reactor for nanoparticle synthesis. This makes it suitable for high-precision synthesis of vanadium oxide nanoparticles, enabling the production of uniform nanoparticles.

[0104] Specific conditions <Examples of demonstration> The machine used was an Anton Paar Synthos 3000, with a reaction temperature of 200°C and a synthesis time of 6 hours.

[0105] <High-temperature firing furnace> The machine will be named Carbolite Gero HTF 1800. Specifically, it will function as a high-temperature firing device to optimize the crystal structure of cathode materials. This will enable uniform firing and improve the quality of the cathode material.

[0106] Specific conditions <Examples of demonstration> The machine was named Carbolite Gero HTF 1800, the settings were a temperature of 600°C, and the firing time was set to 3 hours.

[0107] <Ball mill (crusher)> The machine will be named the Retsch PM100 planetary ball mill. Specific applications include the creation of nanoparticles of Mg-Al alloys and carbon nanotubes, and achieving uniform dispersion.

[0108] Specific conditions <Examples of demonstration> The machine was named Retsch PM100 Planetary Ball Mill, with a set rotation speed of 400 rpm and a grinding time of 2 hours.

[0109] <Nanocomposite Manufacturing Equipment> We will use the machine named Dispermat CN20. A specific application is the uniform compounding of nanocomposite materials (Mg-Al alloy and graphene). This device is suitable for high-precision dispersion of nanomaterials.

[0110] Specific conditions <Examples of demonstration> The machine name was set to CN20, the settings were a rotation speed of 6000 rpm, and the distribution time was set to 1 hour.

[0111] <Manufacturing equipment used for slurry preparation and application> <Slurry Mixer> We will adopt the machine named MTI Corporation MSK-SFM-7.

[0112] Specifically, this device is used to mix positive and negative electrode materials with a binder to create a slurry. It is suitable for processes that form highly accurate and uniform slurries.

[0113] The machine was named MSK-SFM-7, and the settings were a rotation speed of 300 rpm and a mixing time of 30 minutes.

[0114] <Coating equipment (slurry application machine)> We will use the device named Hirano TEC-3000. As a specific use, it is suitable for the process of uniformly applying the slurry to aluminum foil or copper foil. This device can precisely control the coating thickness and maintain the quality. The machine name is set as TEC - 3000, and the set values are a coating thickness of 10 - 20 μm and a coating speed of 0.5 m / min.

[0115] <Drying furnace> Adopt a device with the machine name Yamato DF - 612. As a specific use, it is suitable for drying the applied slurry to create stable electrode materials. This device can achieve uniform drying. The machine name is set as DF - 612, and the set values are a temperature of 100°C to 150°C and a drying time of 2 hours.

[0116] <Manufacturing device used for preparing electrolyte> <Ultrasonic disperser> Adopt a device with the machine name Hielscher UIP1000hdT. As a specific use, uniformly disperse silver nanoparticles in an aqueous solution. This device is a high - power ultrasonic device, suitable for preventing nanoparticle aggregation and maintaining the high quality of the electrolyte. The machine name is set as IP1000hdT, and the set values are an output of 1000 W and a dispersion time of 20 minutes.

[0117] <pH adjuster> Adopt a device with the machine name Metrohm 913 pH meter. As a specific use, accurately adjust the pH of the electrolyte to pH 8 - 9. This device is suitable for adjusting alkaline electrolytes.

[0118] The machine name is set as 913pH meter, and the set value is to adjust the pH within the range of pH 8 - 9.

[0119] <Filter device> Adopt a device with the machine name Sartorius Stedim MF - Millipore. One specific application is to remove impurities from the electrolyte and supply a clean electrolyte.

[0120] The machine was named MF-Millipore, and the filter pore size was set to 0.2 μm.

[0121] <Manufacturing equipment used to create separators> <Film extruder> We will use a machine named Toshiba Machine PE-500. A specific application is extruding PEEK film to create porous films. This device is suitable for producing films of uniform thickness. The machine was named PE-500, and the set thickness was 25 μm.

[0122] <Nanoporous material generating device> The machine name will be the one used in Micromeritics ASAP 2020. A specific application is the creation of porous films with a pore size of 50 nm. This device is suitable for precisely generating nanoscale porous structures. The machine name will be ASAP 2020, and the pore size will be set to 50 nm.

[0123] <Surface treatment equipment> We will use a machine named Plasma Etcher PE-50. Specifically, this device is used to apply an anti-oxidation coating to the separator surface. It is suitable for preventing the permeation of oxygen and moisture, thereby extending the lifespan of cells. The machine was named PE-50, and the processing time was set to 30 minutes.

[0124] <Manufacturing equipment used for assembling cells> <Automatic Cell Stacking Machine> We will use a device with the machine name Manz TFP-550. As a specific use, the positive electrode, separator, and negative electrode are automatically laminated. This device functions as a high-precision automatic stacking machine and is suitable for laminating, for example, a 3V 150Ah rectangular cell. The machine name is TFP-550, and the stacking speed is set to 40 layers per minute as the set value.

[0125] <Vacuum Sealing Machine> An apparatus with the machine name PVA TePla VAS-450 (trade name) is adopted. As a specific use, after injecting the electrolyte, the cell is sealed in a vacuum state to prevent the intrusion of air and moisture from the outside. This device is suitable for ensuring the long-term stability of the cell. The machine name is VAS-450, and the set values are a vacuum degree of -0.1 MPa and a sealing time of 10 minutes.

[0126] <Manufacturing Equipment Used for Quality Control and Inspection> <Cycle Test Device> An apparatus with the machine name Arbin BT2000 (trade name) is adopted. As a specific use, a charge-discharge cycle test is performed. This device is suitable for, for example, confirming the cycle life and charge-discharge characteristics of a 3V 150Ah cell. The machine name is BT2000, and the set values are a current of 15 A and a cycle number of 1000 times.

[0127] <X-ray Inspection Device> An apparatus with the machine name Nikon XT V 160 (trade name) is adopted. As a specific use, the internal structure of the cell is confirmed by X-ray, and it is precisely inspected for any abnormalities or defects. This device is suitable for high-precision inspections. The machine name is XT V 160, and the set values are an X-ray output of 160 kV and a resolution of 5 μm.

[0128] <Voltage / Current Measurement Device> An apparatus with the machine name Keysight Technologies 34461A (trade name) is adopted. Specific applications include measuring the voltage and current characteristics of cells. This device is suitable for high-precision voltage measurement.

[0129] The machine name is 34461A, and the settings are a voltage measurement range of 0-10V and an accuracy of 0.01%.

[0130] <Effects of the second embodiment> By using the machine described above, it is possible to manufacture 3V 150Ah prismatic cells with high precision and reproducibility.

[0131] <Third Embodiment> <Nanobarrier film used in magnesium secondary batteries> This paper describes embodiments of inventions for materials and structures that suppress the formation of passivation films using nanotechnology, for the development of separators and barrier films. It proposes a new method for preventing passivation film formation through chemical and physical approaches to improve the lifespan and performance of magnesium secondary batteries, and attempts to provide scientific proof.

[0132] <Nanobarrier film that prevents the formation of a passivation film> <Structure and function of nanobarrier film> By applying nanotechnology to the film and giving it the following properties, the formation of a passivation film is prevented, ensuring the smooth movement of ions.

[0133] <Multilayer nanostructure> The film is designed with a layered structure on a scale of several nanometers, and magnesium ions (Mg 2+ It allows the selective movement of ) while blocking the entry of oxygen and water molecules.

[0134] <Passive film formation suppression layer> A layer containing metal nanoparticles is provided to suppress the formation of a passivation film on the electrode surface. For example, silver nanoparticles (AgNP) and platinum nanoparticles (PtNP) have an antioxidant effect.

[0135] <Scientific evidence> To prevent the formation of a passivation film, it is crucial to minimize the permeability of oxygen and moisture. Nanobarrier films function as porous and selective ion-permeable membranes, reducing oxygen and moisture permeability to the absolute minimum without hindering ion movement.

[0136] We attempt to quantify the properties of nanofilms using the following transmittance equation (1).

[0137]

number

[0138] Here, P represents the transmittance (the amount of oxygen and water that passes through). D represents the diffusion coefficient (the rate at which oxygen molecules move within graphene oxide). K represents the adsorption coefficient (the amount of oxygen adsorbed onto graphene oxide). L indicates the thickness of the film (thickness of the graphene oxide layer).

[0139] By introducing a nanomultilayer structure, the film thickness L is increased on a nanoscale, and the diffusion coefficient D and adsorption coefficient K decrease, resulting in a significantly lower transmittance P compared to conventional polymer films. In other words, the permeability P of oxygen and moisture can be dramatically reduced, which suppresses oxidation reactions on the electrode surface and prevents the formation of a passivation film.

[0140] <Mechanism for inhibiting passivation membrane formation> When magnesium is exposed to oxygen, a passivation film (magnesium oxide) is formed by the chemical reaction shown in equation (2) below.

[0141]

number

[0142] This reaction indicates that a passivation film (magnesium oxide film) is formed when magnesium is exposed to oxygen. To suppress this reaction, the nanofilm is given the following functions.

[0143] <Suppression of surface oxidation reactions by silver nanoparticles (AgNP)> According to equation (3) below, the silver nanoparticles preferentially react with oxygen and moisture, thereby suppressing the arrival of oxygen to the magnesium electrode and preventing the formation of a passivation film.

[0144]

number

[0145] In the reaction of equation (3) above, silver reacts with oxygen to form a stable silver oxide film on the surface. This film maintains ion permeability and does not hinder the movement of magnesium ions. This reaction prevents the magnesium electrode from being exposed to oxygen and suppresses the formation of a passivation film.

[0146] <Selective ion permeation via porous nanolayers> Forming nanopores of less than 50 nm within the film, Mg 2+ The design allows ions to move freely, but physically prevents oxygen and water molecules from passing through. This nanostructure aims to accelerate ion movement and slow down oxidation reactions.

[0147] <Introduction of new materials> The following new materials will be introduced as materials for the nanobarrier film to enhance its functionality.

[0148] <Graphene Oxide (GO)> It is used as a nanobarrier to suppress the diffusion of oxygen molecules and water molecules. Graphene oxide has extremely high gas barrier properties, so it can almost completely suppress the permeation of oxygen and water.

[0149]

number

[0150] It has been scientifically proven that the introduction of graphene oxide (GO) reduces the oxygen and moisture permeability P by several orders of magnitude compared to conventional polymer-based separators. This makes it possible to physically prevent the formation of a passivation film.

[0151] <Carbon nanotubes (CNTs)> To improve ionic conductivity, it is introduced into the separator. The structure is controlled at the nanoscale, and Mg 2+ To enable efficient ion movement.

[0152] <Experimental Verification Method> To demonstrate the proposed nanobarrier film, the following experiment will be conducted.

[0153] <Oxygen permeability test> The oxygen permeability of the proposed film will be measured to determine the extent to which the introduction of graphene oxide and silver nanoparticles suppresses oxygen permeation.

[0154] <Measurement Method> A gas permeability measuring device is used to quantitatively evaluate the amount of oxygen permeating through the membrane. <Expected results> In films incorporating layers of graphene oxide and silver nanoparticles, the oxygen permeability is significantly lower compared to conventional polymer-based films.

[0155] <Observation of passive film formation on electrode surface> To confirm the presence or absence of a magnesium oxide film on the electrode surface, surface analysis is performed using X-ray photoelectron spectroscopy (XPS) or scanning electron microscopy (SEM).

[0156] <Measurement Method> The thickness of the oxide film formed on the magnesium electrode surface will be measured to confirm the oxidation-inhibiting effect of the proposed film.

[0157] <Expected results> When a film containing silver nanoparticles is used, the formation of a passivation film is suppressed, and it has been confirmed that the electrode surface is hardly oxidized.

[0158] <Consideration> The proposed nanobarrier film utilizes nanotechnology to minimize the permeability of oxygen and moisture, thereby preventing the formation of a passivation film and enabling the smooth movement of magnesium ions. By combining advanced materials such as graphene oxide, silver nanoparticles, and carbon nanotubes, it is expected to dramatically improve battery life and efficiency.

[0159] Further experimental verification and optimization are expected to scientifically prove the effectiveness of this new nanobarrier film.

[0160] The proposed nanobarrier film technology, particularly the multilayer nanofilm structure using silver nanoparticles, graphene oxide, and carbon nanotubes to prevent passivation film formation, can be applied, for example, to Japanese Patent Application Publication No. 2013-56815.

[0161] <An approach to the passivation membrane problem> The proposed methods, such as suppressing the formation of a passivation film using silver nanoparticles and utilizing the barrier properties of graphene oxide, represent novel approaches that have not been attempted with conventional polymer-based separators.

[0162] The design combining the electrode material, separator, and barrier film described above is based on known techniques for theoretically optimizing the performance of magnesium secondary batteries. The effects of the third embodiment will be described below.

[0163] <Combination of electrode material and water-soluble electrolyte> <Protection of magnesium electrodes> By introducing silver nanoparticles and antioxidants, the formation of a passive film on the magnesium electrode surface is suppressed, thereby ensuring the stability of the charge-discharge cycle.

[0164] <Conductivity and pH stability of water-soluble electrolytes> Mg 2+By containing magnesium salts (MgCl2 or MgSO4) at optimal concentrations as an ion source and adjusting the pH to 8-9, high ion transfer efficiency is maintained while preventing electrode corrosion.

[0165] <Separators and barrier films utilizing nanotechnology> The suppression of oxygen and moisture permeation by the "graphene oxide layer" and oxygen capture by "silver nanoparticles" can suppress the formation of a passivation film on the electrode surface, thereby extending the battery life.

[0166] The "carbon nanotube (CNT) layer" is Mg 2+ It promotes ion permeability and improves the efficiency of charging and discharging. This multilayer structure allows each layer to function complementaryly, optimizing both barrier effects and ion transport.

[0167] This design offers a novel approach utilizing nanotechnology to address challenges that have not been adequately solved by existing technologies (such as the formation of passive films in magnesium electrodes, oxygen permeability, and improved ion transport efficiency).

[0168] <List of components of water-soluble electrolyte> The following shows the predicted components of the water-soluble electrolyte and their roles. <Magnesium salt (Mg 2+ Source)> It contains magnesium chloride (MgCl2) or magnesium sulfate (MgSO4) as an ingredient. The role is Mg 2+ They function as an ion source and are responsible for ion transfer during the battery's charge-discharge cycle. These salts readily dissociate in aqueous solutions, supplying the necessary ions. Therefore, the mixing ratio should be 1.0 to 1.5 M (molar concentration), and the concentration should be 10 to 15% (w / v).

[0169] <Buffer solution (potassium adjuster)> In this embodiment, the components of the buffer solution (pH adjuster) include sodium acetate (CH3COONa) and acetic acid (CH3COOH). Its role is to adjust the pH of the electrolyte to 8-9, preventing magnesium corrosion. Within this pH range, magnesium remains stable, and the formation of a passivation film can be suppressed. The mixing ratio is 0.5 to 1.0 M for sodium acetate and 0.1 to 0.5 M for acetic acid, with concentrations of 5 to 10% (w / v) for sodium acetate and 1 to 5% (w / v) for acetic acid.

[0170] <Conductivity enhancer> In this embodiment, the component is ammonium sulfate ((NH4)2SO4). Its role is to improve the conductivity of the electrolyte and increase the efficiency of ion movement. Here, ammonium sulfate enhances ionic conductivity in the electrolyte along with other ionic species.

[0171] In this embodiment, the blending ratio is 0.1 to 0.5 M, and the concentration is 1 to 5% (w / v). <Chelating agent (stabilizer)> Here, ethylenediaminetetraacetic acid (EDTA) is used as the chelating agent (stabilizer). Its role is to prevent the reaction between magnesium ions and impurities, thereby improving the stability of the electrolyte. EDTA is important for controlling ion bonding and preventing precipitation. Furthermore, in this embodiment, the blending ratio is set to 0.01 to 0.05 M, and the concentration is set to 0.1 to 0.5% (w / v).

[0172] <Antioxidant> In this embodiment, the antioxidant component is ascorbic acid (vitamin C). Its role is to suppress oxidation reactions on the magnesium surface, thereby extending the battery life. In this case, ascorbic acid has antioxidant properties and can prevent the oxidation of magnesium. Specifically, the mixing ratio should be 0.01 to 0.05 M, and the concentration should be 0.1 to 0.5% (w / v).

[0173] <Water (solvent)> In this embodiment, the component of water (solvent) adopts distilled water or deionized water. As a role, water (solvent) is a solvent for dissolving the above components and becomes the main component of the electrolyte. Here, as the concentration, an amount sufficient for dissolving the remaining components is used. In this embodiment, the details of the blending ratio and concentration are shown in Fig. 8.

[0174] <Conductivity> Mg 2+ As a source of ions, magnesium chloride (MgCl2) has high conductivity and easily dissociates in water, thus realizing efficient ion movement. Ammonium sulfate complements the conductivity and optimizes the overall ion movement.

[0175] <pH Stability> In this embodiment, by using sodium acetate and acetic acid, the pH is maintained at 8 - 9, which smooths the ion movement while preventing the corrosion of the magnesium electrode. This pH is optimal for preventing the surface oxidation of magnesium and ensuring the long-term stability of the electrolyte.

[0176] <Stabilization> In this embodiment, EDTA chelates magnesium ions and suppresses the effects of precipitation and impurities. Thereby, the long-term stability of the electrolyte is improved and the battery life is extended.

[0177] <Antioxidation> In this embodiment, ascorbic acid exhibits an antioxidant effect and suppresses the oxidation on the surface of the magnesium electrode. Thereby, the electrode life is improved and the stability of the charge-discharge cycle is ensured.

[0178] <Discussion> This water-soluble electrolyte has components and a blending ratio suitable for magnesium secondary batteries, and has high conductivity, antioxidant effect, and pH stability. It is predicted that a long-life and high-efficiency magnesium battery can be realized thereby.

[0179] <Regarding the effect of the graphene oxide layer on inhibiting oxygen and moisture permeability> This section provides supplementary explanations on the extent to which the graphene oxide layer can suppress the permeation of oxygen and moisture, and whether its effectiveness is sufficient compared to conventional technologies. In particular, we will examine whether the pore size and film thickness of the graphene oxide layer are appropriate, and how it deteriorates during long-term use.

[0180] <Methods of scientific proof> The nanosheet structure of graphene oxide has far superior gas barrier properties than polymer-based separators, suppressing the permeation of oxygen and moisture. In particular, because the pore size is designed to be smaller than that of oxygen molecules, low permeability is guaranteed.

[0181] <Prediction and Evidence> For example, by setting the pore size to "0.3~0.5nm" and designing it to a size that oxygen molecules (approximately 0.29nm) and water molecules (approximately 0.27nm) cannot physically penetrate, it is expected that the oxygen permeability will be reduced by several orders of magnitude compared to conventional polymer-based films. Furthermore, by setting the film thickness to "20~30nm", the barrier effect of the multilayer structure will be maximized, demonstrating that barrier properties can be maintained even with long-term use.

[0182] <Scientific proof> Using a gas permeability measuring device, we measure the permeability of oxygen and moisture and present data quantitatively demonstrating how much lower the permeability of the graphene oxide layer is compared to conventional polymer-based separators. This demonstrates that oxygen permeation is suppressed over the long term.

[0183] The graphene oxide layer has a nanosheet structure with a pore size of 0.3-0.5 nm, which physically suppresses the permeation of oxygen and water molecules. Compared to conventional polymer-based separators, it has been scientifically proven that the oxygen permeability is reduced by at least 10 times, minimizing degradation during long-term use.

[0184] <Regarding the efficiency of the oxygen scavenging mechanism using silver nanoparticles> This document explains the mechanism by which silver nanoparticles can efficiently capture oxygen. It also discusses whether the particle size and dispersion concentration are appropriate, and whether they function stably under battery operating conditions.

[0185] <Methods of scientific proof> Silver nanoparticles (AgNPs) readily react with oxygen molecules, forming silver oxide on the particle surface to prevent the oxygen molecules from reacting with magnesium. Since this reaction depends on the particle's surface area, controlling the particle size to "5-10 nm" maximizes both surface area and reaction efficiency.

[0186] <Prediction and Evidence> The smaller the size of the silver nanoparticles, the greater the surface area, which allows for a faster reaction with oxygen molecules. Furthermore, setting the dispersion concentration of the nanoparticles to "0.5~1.0 wt%" is expected to provide sufficient oxygen scavenging capacity to protect the entire magnesium electrode.

[0187] <Scientific proof> We will evaluate the oxidation state of the electrode surface using XPS (X-ray photoelectron spectroscopy) and SEM (scanning electron microscope) to determine how quickly the silver nanoparticle layer reacts with oxygen and how effectively it prevents the formation of a passivation film. Furthermore, we will quantitatively measure the rate constant and reaction efficiency of the oxygen capture reaction to demonstrate its superiority over conventional oxidation prevention technologies. "The silver nanoparticles are controlled to a size of 5-10 nm, and they rapidly react with oxygen molecules to form silver oxide, thereby preventing the formation of a passive film on the magnesium electrode surface. XPS and SEM results confirm that the silver nanoparticle layer effectively captures oxygen molecules and prevents oxidation."

[0188] <Regarding the ion permeability enhancement effect of carbon nanotubes> This section will provide supplementary explanations regarding the extent to which carbon nanotubes (CNTs) can promote ion movement, including specific evidence concerning their conductivity and ion diffusion coefficient. It will also provide supplementary explanations regarding CNT size and dispersion methods.

[0189] <Method of Scientific Proof> Carbon nanotubes have high electrical conductivity and function as a permeation path for Mg 2+ ions. By controlling the diameter of the CNT to "1 - 2 nm" and setting the length to "several μm", magnesium ions can efficiently move inside the CNT.

[0190] <Prediction and Basis> By dispersing CNT at a concentration of "1 - 3 wt%", it is predicted that the ion migration path in the membrane will be optimized and the internal resistance will be significantly reduced. Also, due to the conductivity of CNT, efficient ion migration is possible during the charge and discharge cycles of the battery.

[0191] <Scientific Proof> Using a battery performance evaluation device, measure the change in the permeability of Mg 2+ ions and the internal resistance when applying a barrier film containing CNT. This demonstrates that CNT promotes ion migration and improves the charge and discharge efficiency.

[0192] "Carbon nanotubes are designed to have a diameter of "1 - 2 nm" and a length of several μm, and promote the permeation of Mg 2+ ions. This is based on known technology where, from the measurement results of the internal resistance, it has been confirmed that the film containing CNT significantly improves the ion permeability of the battery and the charge and discharge efficiency is improved."

[0193] <Regarding the Interaction and Durability of Multilayer Nanobarrier Films> Supplement the explanation on how durable the multilayer structure is during long-term use and how the battery performance is maintained. In particular, consider whether the bonding and interaction between layers are strong enough and the deterioration between layers.

[0194] <Method of Scientific Proof> Each layer of graphene oxide, silver nanoparticles, and carbon nanotubes has a different role and exhibits a complementary effect. Thereby, while suppressing the permeation of oxygen and moisture, Mg 2+It promotes ion permeability. By optimizing the thickness and bonding strength of each layer, it maintains stable barrier performance over the long term.

[0195] <Prediction and Evidence> By appropriately designing the thickness of each layer (graphene oxide layer: 20-30 nm, silver nanoparticle layer: 10-20 nm, carbon nanotube layer: 30-40 nm) and strengthening the bonding strength between layers, it is predicted that film separation and degradation will not occur even after long-term use.

[0196] <Scientific proof> Tensile and thermal degradation tests will be conducted to measure the mechanical strength of the film and the durability of the interlayer bonds. Furthermore, the maintenance of barrier performance during long-term charge-discharge cycles will be confirmed to demonstrate the effect of multilayer films in extending battery life. "Multilayer nanobarrier films maintain their barrier performance without degradation even after long-term use, thanks to the complementary roles of each layer. Based on known technology, tensile and thermal degradation tests have confirmed that the interlayer bonds are strong and the film functions stably even during long-term charge-discharge cycles."

[0197] The following describes the technological differentiation points of the magnesium secondary battery using the nanobarrier film of the third embodiment.

[0198] Below, we will explain in detail the barrier film containing graphene oxide as a key technological differentiator. Structure of the graphene oxide layer <Nanosheet size> The graphene oxide (GO) layer has a nanoscale sheet structure. The thickness of each sheet is approximately 1-2 nm, and the lateral size of the sheets is set to 500 nm to 1 μm.

[0199] <Pore size (pore diameter)> To prevent the permeation of oxygen and moisture, the pore size within the graphene oxide layer is set to "0.3-0.5 nm," which is equivalent to or slightly smaller than the size of oxygen molecules (approximately 0.29 nm) and water molecules (approximately 0.27 nm). This physically suppresses the permeation of oxygen and moisture.

[0200] <thickness> For example, the overall thickness of the graphene oxide layer is set to "20-30 nm," and it has a structure made up of multiple stacked nanosheets. This allows for consideration of temperature and hardness.

[0201] <Operating temperature range> The graphene oxide layer maintains barrier properties against oxygen and moisture within the typical operating temperature range of magnesium secondary batteries, for example, "-20°C to 80°C". Furthermore, due to graphene's heat resistance, the structure remains stable even after prolonged use.

[0202] <Hardness> The graphene oxide layer has a hardness of "5.0 GPa or higher," providing high durability and maintaining the mechanical strength necessary for battery operation.

[0203] <Chemical formulas and theories> The barrier effect of the graphene oxide layer in suppressing oxygen and moisture permeation can be quantitatively explained by the following permeability equation.

[0204]

number

[0205] Here, P represents the transmittance (the amount of oxygen or water that passes through). D represents the diffusion coefficient (the rate at which oxygen molecules move within graphene oxide). K represents the adsorption coefficient (the amount of oxygen adsorbed onto graphene oxide). L indicates the thickness of the film (thickness of the graphene oxide layer). In this case, due to the multi-layer structure of graphene oxide, the thickness L of the film increases, and the diffusion coefficient D and adsorption coefficient K decrease, resulting in a significantly lower transmittance P compared to conventional polymer films.

[0206] Hereinafter, as a technical differentiation point, the antioxidant layer containing silver nanoparticles will be described in detail. Size and concentration of nanoparticles

[0207] <Particle size> Silver nanoparticles (AgNP) are controlled to a size of "5 to 10 nm" and are designed so that oxygen molecules (about 0.29 nm) can react quickly on the surface.

[0208] <Dispersion concentration of particles> Silver nanoparticles are dispersed at a ratio of "0.5 to 1.0 wt%" with respect to the surface area of the barrier film, ensuring a sufficient amount to protect the entire surface of the magnesium electrode from oxygen reaction.

[0209] <Oxygen capture mechanism> <Chemical reaction formula> The oxygen supplementation of silver nanoparticles is shown by the following chemical reaction formula.

[0210]

Equation

[0211] Here, Ag: Silver nanoparticles O2: Oxygen AgO: Silver oxide

[0212] By this reaction, oxygen is captured on the surface of silver nanoparticles, preventing oxygen from reacting with magnesium.

[0213] <Operating temperature and hardness> <Operating temperature range> The silver nanoparticle layer functions in an operating temperature range of "-20°C to 80°C" and enables the formation and retention of a silver oxide film.

[0214] <Hardness> This layer is relatively flexible and designed to accommodate the expansion and contraction that occur during the battery's charge and discharge cycles.

[0215] <Chemical formulas and theories> The efficiency of oxygen capture by silver nanoparticles depends on the surface area of ​​the silver and the particle size. The probability that oxygen molecules reach the surface of the silver nanoparticles and that an oxidation reaction occurs is expressed as follows:

[0216]

number

[0217] Here, R represents the oxygen reaction rate. k represents the reaction rate constant. {O2} indicates the oxygen concentration. A{AgNP} represents the surface area of ​​the silver nanoparticle.

[0218] As particle size decreases, the surface area increases, and according to the above formula, A{AgNP} increases, improving the oxygen reaction rate R, thus enabling more efficient oxygen capture.

[0219] Below, we will explain in detail the ion permeability-enhancing layer containing carbon nanotubes as a key point of technological differentiation. <Size and concentration of carbon nanotubes> <Pipe diameter (diameter)> The diameter of carbon nanotubes (CNTs) is "1-2 nm", and Mg 2+ It is set to a size that allows ions (approximately 0.072 nm) to move smoothly.

[0220] <Chief> Each carbon nanotube (CNT) is several micrometers long, shortening the ion transport path between electrodes.

[0221] <Dispersion concentration> The dispersion concentration of CNTs is set to "1-3 wt%", which improves conductivity while ensuring the mechanical strength of the film.

[0222] <Ion Permeation Mechanism> <Ion transport velocity> Carbon nanotubes have excellent electrical conductivity and promote ion movement. Mg 2+ The diffusion rate increases as ions pass through the carbon nanotube (CNT).

[0223] <Temperature and Hardness> <Operating temperature range> The CNT layer functions stably in the range of -20°C to 80°C, and optimizes ion permeation.

[0224] <Hardness> CNTs possess high mechanical strength and can accommodate the expansion and contraction of batteries while maintaining the overall rigidity of the film.

[0225] <Chemical formulas and theories> Mg 2+ The diffusion rate of ions is described based on Fick's law. Since carbon nanotubes promote ion movement, the diffusion rate J is expressed as follows:

[0226]

number

[0227] Here, J represents the flux (diffusion rate) of ions. D represents the diffusion coefficient (efficiency of ion movement within the CNT), dC / dx represents the concentration gradient.

[0228] Due to carbon nanotubes, the diffusion coefficient D increases significantly from equation (8) above, and Mg 2+ Because the ion transmission rate is improved, efficient ion transport becomes possible.

[0229] Below, we will explain in detail the multilayer nanobarrier film as a key point of technological differentiation. <Multilayered Structure Design> <Thickness of the graphene oxide layer> 20-30nm

[0230] <Thickness of the silver nanoparticle layer> 10-20nm

[0231] <Thickness of the carbon nanotube layer> 30-40nm <Multilayer Interactions>

[0232] Each layer not only functions independently but also plays a complementary role. The graphene oxide layer blocks oxygen and moisture, the silver nanoparticle layer captures oxygen, and the carbon nanotube layer contains Mg 2+ By promoting ion movement, it achieves highly efficient charging and discharging while preventing the formation of a passivation film.

[0233] <Chemical formulas and theories> Oxygen permeability P due to multilayer structure multi The decrease is given by the following equation (9).

[0234]

number

[0235] Here, P multi This indicates the transmittance of the entire multilayer film. P i This indicates the transmittance of each layer. Li indicates the thickness of each layer.

[0236] The synergistic effect of each layer results in an oxygen permeability P multi This is significantly reduced, and the overall protective effect of the membrane is enhanced.

[0237] Below, we will explain in detail the magnesium secondary battery as a key point of technological differentiation. <Overall battery configuration> Magnesium secondary batteries using nanobarrier film suppress oxygen permeation while using a normal electrolyte, and Mg 2+This enables efficient ion movement, dramatically improving battery life and charge / discharge efficiency.

[0238] <Operating temperature and hardness> The battery as a whole is guaranteed to operate within a temperature range of -20°C to 80°C, and its structural strength is ensured to be 5 GPa or higher.

[0239] Thus, in the third embodiment, a multilayer nanobarrier film combining graphene oxide, silver nanoparticles, and carbon nanotubes can effectively suppress the formation of a passivation film and improve the performance of a magnesium secondary battery.

[0240] The disclosure relating to the present invention described above can be summarized to at least the following: (1) A positive electrode comprising a vanadium oxide (V2O5) or molybdenum oxide (MoO3) that has been nanostructured by mixing conductive carbon nanotubes; a negative electrode comprising a nanostructured magnesium-aluminum alloy (Mg-Al alloy) and a magnesium-graphene composite material in a nanosheet structure obtained by compounding graphene and magnesium in a solution process; and a water-soluble electrolyte containing nanoparticles disposed between the positive electrode and the negative electrode, wherein the positive electrode and the negative electrode are separated by a separator.

[0241] (2) The present invention is characterized in that a nanobarrier film made of a porous polymer nanofilm for suppressing passivation is sandwiched between the separator and the negative electrode.

[0242] (3) A method for manufacturing a magnesium secondary battery according to claim 2, The system includes: a raw material preparation step for preparing the raw materials for the positive electrode and the negative electrode; a slurry preparation and electrode coating step for separately preparing slurries and coating the positive electrode material and the negative electrode material prepared in the raw material preparation step; an electrolyte preparation step for adjusting the pH of distilled water to which NaOH or KOH has been added and uniformly dispersing silver nanoparticles to create a water-soluble electrolyte; and a separator preparation step for creating a nanoporous separator. It is characterized by the following: [Explanation of Symbols]

[0243] 1. Magnesium secondary battery 2. Positive electrode (cathode) 3. Negative electrode (anode) 4 Separators 5 Electrolyte 6. Load or power supply 7 Positive electrode current collector 8 Nanobarrier film 9 Nanostructured oxides 501 Raw material preparation process 502 Slurry preparation and electrode coating process 503 Electrolyte preparation process 504 Separator preparation process 505 Battery cell assembly process 506 Quality Inspection Process

Claims

1. A mixture of conductive carbon nanotubes and nanostructured vanadium oxide (V ２ O ５ A positive electrode having ) or molybdenum oxide (MoO3), A negative electrode having a nanostructured magnesium-aluminum alloy (Mg-Al alloy) and a magnesium-graphene composite material with a nanosheet structure formed by compounding graphene and magnesium in a solution process, Displaced between the positive electrode and the negative electrode, and comprising a water-soluble electrolyte containing nanoparticles, The positive electrode and the negative electrode are separated by a separator. A magnesium secondary battery characterized by the following features.

2. The magnesium secondary battery according to claim 1, characterized in that a nanobarrier film made of a porous polymer nanofilm for suppressing passivation is sandwiched between the separator and the negative electrode.

3. A method for manufacturing a magnesium secondary battery according to claim 2, The system includes: a raw material preparation step for preparing the raw materials for the positive electrode and the negative electrode; a slurry preparation and electrode coating step for separately preparing slurries and coating the positive electrode material and the negative electrode material prepared in the raw material preparation step; an electrolyte preparation step for adjusting the pH of distilled water to which NaOH or KOH has been added and uniformly dispersing silver nanoparticles to create a water-soluble electrolyte; and a separator preparation step for creating a nanoporous separator. A method for manufacturing a magnesium secondary battery, characterized by the following features.

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