A porous seawater electrode and a preparation method thereof

Abstract

The application discloses a kind of porous seawater electrode and preparation method, belong to mixed battery and its manufacturing technical field.The method includes:1) in the seawater solution of sodium chloride at least 0.35% generation coordination crystal particles, form porous seawater;2) with good carbon felt as solid electrode;3) with dialysis bag porous seawater and solid electrode are packaged together, dialysis bag does not allow coordination crystal particles to go in and out, but allows gas molecule and Na + Ion free in and out, can constantly update the dissolved oxygen in bag;4) coordination crystal particles in porous seawater, by sodium ion intercalation / de-intercalation, between the oxygen of update and solid electrode, set up the bridge of electron transfer.The method of the application is simple to operate, and the material is environment-friendly.The shape and size of the electrode made are easy to change, and the problems of dissolved oxygen update and electron transfer difficulty are solved, and the seawater battery made thereby can provide continuous power.

Description

Technical Field

[0001] This invention relates to the field of hybrid battery technology and its manufacturing technology, specifically a porous seawater electrode and its preparation method. Background Technology

[0002] Marine engineering has greatly expanded human living space and has the potential to reduce conflicts on land. Therefore, technologies such as seawater batteries and natural gas production have been developed as key components supporting marine engineering. For many of these technologies, electron transfer between solid electrodes and dissolved oxygen molecules in seawater is considered crucial. Typically, adsorbed oxygen molecules donate / accept electrons to the electrode. To facilitate these processes, electrodes are fabricated with porous structures to increase the contact surface area and accelerate electron transfer kinetics. However, the inherent solubility of dissolved oxygen molecules is generally low, requiring renewal through diffusion. This means the probability of collisions between oxygen molecules and the electrode cannot be high, resulting in a slow rate of oxygen molecule renewal.

[0003] Directly capturing oxygen molecules from the air to improve oxygen molecule renewal is also unsuitable because the diffusion distance of renewed oxygen molecules to the solid electrode is too long, resulting in a still low probability of collision between the renewed oxygen molecules and the electrode. The key to solving this problem is finding an active liquid medium that can effectively bridge electron transfer between dissolved oxygen molecules and the electrode. Seawater is the most readily available liquid medium in the ocean, but it is inert for electron transfer. Prussian blue nanoparticles, microporous metal-CN-metal frameworks, can bridge electron transfer between dissolved oxygen molecules and the solid electrode through the intercalation / deintercalation of Na+ ions. Therefore, porous seawater is a suitable candidate material for achieving dissolved oxygen renewal and accelerating subsequent electron transfer. Summary of the Invention

[0004] The purpose of this invention is to optimize the problems of difficult dissolved oxygen renewal and difficult electron transfer between solid electrodes and dissolved oxygen molecules in seawater during the practical application of seawater batteries. This invention provides a porous seawater electrode and its preparation method. The invention is simple to operate, uses environmentally friendly materials, and is easy to expand.

[0005] The specific technical solution of this invention is as follows:

[0006] A method for preparing a porous seawater electrode, the porous seawater electrode comprising a solid electrode, porous seawater, and a flexible membrane that allows gas molecules and ions in seawater to freely enter and exit, but does not allow coordination crystal particles to enter and exit; the preparation method specifically includes the following steps:

[0007] Step 1: Add ferric salt and ferrocyanide salt to seawater in a 1:1 molar ratio. Stir for 3-5 minutes to form a homogeneous and continuous slurry, thus obtaining porous seawater.

[0008] The ferric salt is ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, ferric iodide, or ferric bromide;

[0009] The ferrocyanide salt is potassium ferrocyanide or sodium ferrocyanide.

[0010] The tools mentioned are glass rods, iron rods, magnesium alloy rods, aluminum alloy rods, and electric mixers;

[0011] The seawater is natural seawater with at least 1 ppm dissolved oxygen and at least 0.35% sodium chloride, seawater prepared with sea salt, or simulated seawater prepared with sodium chloride or potassium chloride.

[0012] Step 2: Cut a flexible membrane that allows gas molecules and ions in seawater to enter and exit freely, but does not allow coordination crystal particles to enter and exit.

[0013] The flexible membrane is a dialysis bag or a transdermal bag.

[0014] Step 3: Cut the solid electrode into a certain shape and clamp it with a conductive clip.

[0015] The solid electrode is made of carbon felt, carbon cloth, titanium, copper, or nickel.

[0016] The conductive clip is a platinum sheet electrode clip or an alligator clip.

[0017] Step 4: Use a flexible membrane that allows gas molecules and ions in seawater to freely enter and exit, but does not allow coordinated crystal particles to enter and exit.

[0018] Porous seawater and a solid electrode were wrapped together and sealed using a tool to obtain the desired result.

[0019] Porous seawater electrode. Among them,

[0020] The tool is a rubber band, nylon rope, or glue.

[0021] This invention is simple to operate and uses environmentally friendly materials. The prepared electrode can be easily expanded by increasing the volume of the dialysis bag; in practical seawater battery applications, it can effectively renew dissolved oxygen molecules and accelerate subsequent electron transfer, and the seawater battery made with it can provide continuous power. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the porous seawater electrode of the present invention;

[0023] Figure 2 This is a schematic diagram of a seawater battery assembled using the porous seawater electrode of the present invention as the cathode.

[0024] Figure 3This is a chronopotential diagram of the seawater battery prepared in Example 1 of the present invention;

[0025] Figure 4 This is a chronopotential diagram of the seawater battery prepared in Example 2 of the present invention. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0027] See Figure 1 The electrode structure of this invention is shown in the figure. Ferric salt and ferrocyanide are added to seawater 1 in a specific ratio to generate coordination crystal particles 2, forming porous seawater. A section of flexible dialysis bag 3 is cut. Carbon felt 4 is cut to a shape and size matching the flexible dialysis bag and clamped with a platinum electrode clip 5. The porous seawater and carbon felt 4 are then wrapped in the flexible dialysis bag 3 and sealed with a rubber band, with the upper end of the platinum electrode clip 5 exposed outside the flexible dialysis bag 3. This constitutes the electrode described in this invention.

[0028] Example 1

[0029] This embodiment provides a method for preparing a porous seawater electrode and an assessment of its feasibility in seawater batteries.

[0030] Step 1: Add 14g of ferric chloride hexahydrate and 15.6g of sodium ferrocyanide to 100mL of natural seawater to directly generate Prussian blue. Stir with a glass rod for 5 minutes to form a homogeneous and continuous slurry, obtaining porous seawater with a theoretical solid fraction of 15wt%. Cut a dialysis bag with a length of 20cm, a diameter of 77mm, and a molecular weight cutoff of 7000. Cut carbon felt into a shape of 5cm×5cm×1cm and clamp it with a platinum electrode clamp. Wrap the carbon felt and porous seawater inside the dialysis bag, and seal the top and bottom of the dialysis bag with rubber bands. A porous seawater electrode is thus prepared.

[0031] Step 2: Cut the magnesium alloy into magnesium alloy sheets with dimensions of 5cm × 5cm × 0.1cm.

[0032] Step 3: Assembling the seawater battery. (See attached document) Figure 2 15L of natural seawater is placed in an electrolytic cell to serve as the electrolyte for the seawater battery. The porous seawater electrode obtained in step 1 and the magnesium alloy sheet obtained in step 2 are then placed in the electrolytic cell to serve as the cathode and anode of the seawater battery, respectively. The cathode and anode are connected to the two poles of a power supply via copper wires to output a stable direct current.

[0033] Figure 3This is a chronopotential diagram of the seawater battery assembled in this embodiment. The test conditions are as follows: 15L of natural seawater is placed in an electrolytic cell as the electrolyte; the porous seawater electrode obtained in step 1 and the magnesium alloy sheet obtained in step 2 are placed in the electrolytic cell as the cathode and anode, respectively. The cathode and anode are led out with copper wires and connected to the electrochemical workstation in chronopotential mode for discharge at a current of 10mA. Figure 3 The voltage-time relationship is shown in the figure.

[0034] In this embodiment, when the porous seawater electrode and the magnesium alloy sheet are immersed in seawater, the dialysis bag allows electrons and ions to pass through. The low redox potential of the magnesium alloy drives electrons to move towards the porous seawater electrode and ultimately transfer them to the porous seawater. The Prussian blue coordination crystal accepts electrons and simultaneously absorbs a cation from the seawater, forming a Prussian white coordination crystal. The metallic magnesium dissolves in the seawater in ionic form. The flow of electrons generates an electric current. The dialysis bag allows dissolved oxygen molecules to freely enter and exit, thus continuously renewing the dissolved oxygen within the bag. This dissolved oxygen oxidizes the Prussian white coordination crystal, releasing a cation and restoring it to a Prussian blue coordination crystal. This cycle repeats, providing a stable current. Figure 3 As can be seen, the battery can continuously discharge at a current of 10mA, which shows that this porous seawater electrode can be effectively applied in seawater batteries, solving the problem of difficult dissolved oxygen renewal and electron transfer during the use of seawater batteries.

[0035] Example 2

[0036] This embodiment provides a method for fabricating porous seawater electrodes of different sizes and their application in seawater batteries.

[0037] Step 1: Add 6.5g of ferric sulfate and 13.8g of potassium ferrocyanide to 100mL of natural seawater to directly generate Prussian blue. Stir with a glass rod for 5 minutes to form a homogeneous and continuous slurry, obtaining porous seawater with a theoretical solid fraction of 10wt%. Cut a dialysis bag with a length of 20cm, a diameter of 77mm, and a molecular weight cutoff of 7000. Cut carbon felt into a shape of 5cm×5cm×1cm and clamp it with a platinum electrode clamp. Wrap the carbon felt and porous seawater inside the dialysis bag, and seal the top and bottom of the dialysis bag with rubber bands. The resulting 100mL porous seawater electrode is shown.

[0038] Step 2: Add 13g of ferric sulfate and 27.6g of potassium ferrocyanide to 200mL of natural seawater to directly generate Prussian blue. Stir with a glass rod for 5 minutes to form a homogeneous and continuous slurry, obtaining porous seawater with a theoretical solid fraction of 10wt%. Cut a dialysis bag with a length of 35cm, a diameter of 77mm, and a molecular weight cutoff of 7000. Cut carbon felt into a shape of 5cm×5cm×1cm and clamp it with a platinum electrode clamp. Wrap the carbon felt and porous seawater inside the dialysis bag, and seal the top and bottom of the dialysis bag with rubber bands. Obtain a 200mL porous seawater electrode.

[0039] Step 3: Cut the magnesium alloy into magnesium alloy sheets with dimensions of 5cm × 5cm × 0.1cm.

[0040] Step 4: Assembling the seawater battery. (See attached document) Figure 2 15L of natural seawater is placed in an electrolytic cell to serve as the electrolyte for the seawater battery. The porous seawater electrode obtained in step 1 or 2 and the magnesium alloy sheet obtained in step 3 are then placed in the electrolytic cell to serve as the cathode and anode of the seawater battery, respectively. The cathode and anode are led out with copper wires and connected to the two poles of a power supply to output a stable DC current.

[0041] Figure 4 These are the chronopotential curves of the two sets of seawater batteries assembled in this embodiment. The battery using a 100mL porous seawater electrode corresponds to discharge curve a, and the battery using a 200mL porous seawater electrode corresponds to discharge curve b. The test conditions are as follows: 15L of natural seawater is placed in the electrolytic cell as the electrolyte for the seawater battery. The porous seawater electrode obtained in step 1 or step 2 and the magnesium alloy sheet obtained in step 3 are then placed in the electrolytic cell as the cathode and anode of the seawater battery, respectively. The cathode and anode are led out with copper wires and connected to the chronopotential mode of the electrochemical workstation, where a discharge current of 10mA is applied to obtain... Figure 4 The voltage-time relationship is shown in the figure.

[0042] In this embodiment, when the porous seawater electrode and the magnesium alloy sheet are immersed in seawater, the dialysis bag allows electrons and ions to pass through. The low redox potential of the magnesium alloy drives electrons to move towards the porous seawater electrode and ultimately transfer them to the porous seawater. The Prussian blue coordination crystal accepts electrons and simultaneously absorbs a cation from the seawater, forming a Prussian white coordination crystal. The metallic magnesium dissolves in the seawater in ionic form. The flow of electrons generates an electric current. The dialysis bag allows dissolved oxygen molecules to freely enter and exit, thus continuously renewing the dissolved oxygen within the bag. This dissolved oxygen oxidizes the Prussian white coordination crystal, releasing a cation and restoring it to a Prussian blue coordination crystal. This process repeats continuously, providing a stable current.

[0043] In this embodiment, porous seawater electrodes of different sizes can be fabricated simply by increasing the volume of the dialysis bag. Furthermore, the volume of the dialysis bag is directly related to the total dissolved oxygen and Prussian blue particles in the porous seawater electrode. Therefore, by changing the volume of the dialysis bag, the capacity of the seawater battery using the porous seawater electrode can be altered. The operation method is simple, and the materials are environmentally friendly.

Claims

1. A method for preparing a porous seawater electrode, characterized in that, Specifically, the following steps are included: Step 1: Add ferric salt and ferrocyanide salt to seawater in a 1:1 molar ratio. Stir for 3-5 minutes to form a uniform and continuous slurry, thus obtaining porous seawater. The tool can be a glass rod, iron rod, magnesium alloy rod, aluminum alloy rod, or electric mixer. The seawater can be natural seawater with at least 1 ppm dissolved oxygen and at least 0.35% sodium chloride, simulated seawater prepared with sodium chloride or potassium chloride, or seawater prepared with sea salt. Step 2: Cut a flexible membrane that allows gas molecules and ions in seawater to freely enter and exit, but does not allow coordinated crystal particles to enter and exit; the flexible membrane is a dialysis bag or a transdermal bag; Step 3: Cut the solid electrode into a rectangular shape and clamp it with a conductive clip; the solid electrode is carbon felt, carbon cloth, titanium, copper or nickel; the conductive clip is a platinum electrode clip or an alligator clip; Step 4: Wrap the porous seawater and solid electrode with the flexible membrane and seal it with a tool to obtain the porous seawater electrode; wherein the tool is a rubber band, nylon rope or glue.

2. The method for preparing a porous seawater electrode as described in claim 1, characterized in that, The ferric salt mentioned in step 1 is ferric chloride, ferric sulfate, ferric nitrate, ferric acetate, ferric iodide, or ferric bromide; the ferrocyanide salt is potassium ferrocyanide or sodium ferrocyanide.

3. A porous seawater electrode prepared by the method described in claim 1.

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