A magnesium fuel cell

Abstract

The present application relates to a kind of magnesium fuel cell, including single cell or 2 above single cell circuit series, parallel or series-parallel hybrid composition battery;The single cell includes a hollow single cell shell, is transversely arranged with a transition layer in the middle and lower part in single cell shell, the four peripheral edges of transition layer are sealedly connected with shell inner wall surface, transition layer will shell be divided into two upper and lower chambers not communicated each other, electrolyte is filled in upper chamber as electrolyte chamber, lower chamber is filled with regenerative liquid as regenerative liquid chamber;Anode, air cathode are placed in electrolyte chamber;The transition layer changes with the state change of battery discharge process, so that regenerative liquid can react with the discharge product in single cell through transition layer;The regenerative liquid is acid solution.The long-time continuous discharge feasibility of magnesium fuel cell is significantly improved.

Description

Technical Field

[0001] This invention relates to a magnesium fuel cell. Specifically, it is a magnesium fuel cell that uses magnesium metal or an alloy as the anode and can be used for long-term, maintenance-free continuous discharge. Background Technology

[0002] Magnesium fuel cells possess numerous advantages, including high theoretical energy density, good safety, no pollution from reactants and products, quiet and discreet operation, long dry-state storage time, and continuous and stable power supply. Integrated magnesium-air fuel cells have broad application prospects in mobile power fields such as communication power, field emergency power, and storage power, while magnesium-seawater fuel cells have broad application prospects in the field of marine equipment power. Taking the magnesium / air battery as an example, its theoretical energy density reaches as high as 3910Wh / kg. The electrode reactions and overall battery reactions of the magnesium / air battery are as follows:

[0003] Anode electrode reaction: -2.69V (1)

[0004] Cathode electrode reaction: +0.4V (2)

[0005] Overall battery reaction: +3.09V (3)

[0006] As shown in the above formula, the magnesium / air battery consumes metallic magnesium, oxygen from the air, and water during the reaction process, producing magnesium hydroxide. After a period of reaction, the metal anode is gradually consumed, and the product magnesium hydroxide gradually accumulates in the electrolyte. Magnesium hydroxide, also known as caustic magnesia or lightly calcined magnesia, has a molecular weight of 58.33 and a density of 2.39 g / cm³. -3 It is sparingly soluble in water (solubility at 18℃ is 0.0009 g / 100 mL), but soluble in strongly acidic solutions. Ordinary magnesium hydroxide is mostly hexagonal or amorphous plate-like crystals, with a thermodynamically stable structure of hexagonal plates. This leads to the presence of Mg on the (001) crystal plane within the hexagonal plates. 2+ It has the highest density. The positively charged ion-bearing crystal facets are polar, easily attracting negatively charged ions. Furthermore, the significant difference in electronegativity between hydrogen and oxygen atoms causes the electron cloud to shift towards oxygen atoms, making hydrogen atoms semi-exposed protons. Therefore, magnesium hydroxide crystals exhibit strong polarity and hydrophilicity, and tend to aggregate due to hydrogen bonding between molecules. If the battery is continuously discharged for a long time, the accumulation of insoluble magnesium hydroxide not only affects the ion conduction rate in the electrolyte and increases polarization, but also causes the aggregated volume to expand several times, making a single cell prone to cracking and damage. Conventional practices include replacing the electrolyte and cleaning the products periodically (every few hours), increasing the difficulty of use; or increasing the electrolyte cavity volume to accommodate the products, increasing the amount of electrolyte used, which greatly reduces the battery's specific energy, a major reason limiting its practical application. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by proposing a novel magnesium fuel cell with high specific energy and the ability to continuously discharge for extended periods without maintenance.

[0008] A magnesium fuel cell includes a battery pack consisting of a single cell or two or more single cells connected in series, parallel, or a combination of series and parallel connections.

[0009] The single cell includes a single cell housing, a metal anode perpendicular to the bottom of the single cell housing, air cathodes placed on opposite sides of the battery housing and parallel to the metal anode, a transition layer with its bottom perpendicular to the metal anode, and an electrolyte chamber composed of the single cell housing, the metal anode, the air cathode and the transition layer, and a regeneration chamber composed of the transition layer and the single cell housing.

[0010] The transition layer changes state as the battery discharges, allowing the regenerated liquid to react with the discharge products in the single cell through the transition layer.

[0011] The state change during battery discharge refers to the changes in pH value, electric field strength, magnetic field strength, ion concentration, temperature, etc., within the battery as the reaction proceeds;

[0012] The transition layer is a solid membrane or gel membrane made of one or more of the following: pH-responsive polymer materials, magnetic field and / or electric field-responsive polymer materials, temperature-sensitive materials, ion-sieving materials, and porous materials.

[0013] The pH-responsive polymer material contains weakly acidic (weakly basic) groups, such as amino, sulfonic acid, and carboxyl groups. As the pH value and ionic strength of the medium change, the ionization of these groups causes changes in the ion concentration inside and outside the polymer, leading to the dissociation of hydrogen bonds between macromolecular chain segments and resulting in discontinuous swelling volume changes or changes in solubility. At low pH, the carboxylic acid groups of polyacid gels do not dissociate, and the gel is relatively non-swellable. As the pH increases, the carboxylic acid groups dissociate, the charge density increases, and the polymer swells. Polybasic gels are the opposite, that is, the degree of swelling increases as the pH decreases.

[0014] The polyacid-based pH-sensitive polymeric materials include acrylic copolymers (polyacrylic acid-co-acrylonitrile and polyacrylic acid-N-isopropylacrylamide polymers, etc.), acrylic grafts (polypropylene-polycarbonate films, etc.), acrylic interpenetrating polymer networks, acrylic complexes (polymethacrylic acid / gelatin and polyacrylic acid / gelatin complexes, etc.), and other polyacid-based pH-sensitive polymers (chitosan, gels formed by mild crosslinking of alkyl methacrylate and dimethylaminoethyl acrylate, etc.).

[0015] The aforementioned alkali-based pH-sensitive polymers, chitosan polymers (crosslinked chitosan / polyether semi-interpenetrating network hydrogels, crosslinked chitosan / silk fibroin semi-interpenetrating network polymers, etc.), and N,N-dialkylaminoalkyl acrylate polymers, etc.

[0016] The electrically and / or magnetically responsive polymeric materials refer to materials with a fluid polymer backbone crosslinked to have an electric field (carrying a charge) and / or magnetic field response.

[0017] The magnetic field response includes ferrite magnets, rare earth magnets, AlNiCo alloy magnets, and mixtures of one or more of these.

[0018] For example, when iron oxide colloidal particles and titanium dioxide colloidal particles are dispersed in polydimethylsiloxane (PMDS), applying an electric or magnetic field of a certain strength can cause the particles in the polydimethylsiloxane (PDMS) to become oriented.

[0019] For example, using acrylamide (AAm), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and dimethylaminoethyl methacrylate chloride (DMA) as monomers, two types of gels were prepared by free radical polymerization: anionic P(AAm-co-AMPS) / MMT nanocomposite gel and cationic P(AAm-co-DMC) nanocomposite gel. MMT, an inorganic nanoparticle of montmorillonite, can act as a crosslinking point, providing reinforcement.

[0020] The temperature-sensitive material is a polymer material with both hydrophilic and hydrophobic groups on its macromolecular chain. As the solution temperature changes, the hydrophilicity and hydrophobicity of the groups and the hydrogen bonding interactions change, which in turn leads to a change in the molecular chain conformation (from an extended random coil to a coiled spherical shape, etc.), thus achieving temperature responsiveness.

[0021] The temperature-sensitive material includes acrylamide polymers, etc., whose side chains are substituted with isopropyl, ethyl, propyl, cyclopropyl, diethyl, pyrrolyl, or piperidinyl.

[0022] For example, poly(N-isopropylacrylamide) (PNIPA) will expand in volume when the solution temperature is below the minimum critical dissolution temperature (LCST) and shrink in volume when the solution temperature is above the LCST.

[0023] The ion sieving materials include proton exchange membranes that sieve H+ ions, including fluorosulfonic acid type proton exchange membranes; Nafion recast membranes; non-fluoropolymer proton exchange membranes; and novel composite proton exchange membranes, etc.

[0024] The regenerated solution is composed of inorganic or organic acids such as perchloric acid, sulfuric acid, hydrochloric acid, nitric acid, iodic acid, oxalic acid (oxalic acid), sulfurous acid, phosphoric acid, pyruvic acid, nitrous acid, carbonic acid, citric acid, malic acid, gluconic acid, formic acid, lactic acid, benzoic acid, acrylic acid, acetic acid, propionic acid, stearic acid, hydrosulfuric acid, hypochlorous acid, and boric acid.

[0025] The transition layer is fixed to the single-cell shell below the electrolyte chamber and above the regeneration chamber by one or more of the following methods: injection molding, bonding, welding, and mechanical fastening.

[0026] The single battery casing material is made of one or more of the following: ABS plastic, polyvinyl chloride (PVC), high-density polyethylene (HDPE), polypropylene (PP), polystyrene / modified polystyrene (PS), polyoxymethylene (POM), polyphenylene ether (PPO), polyimide (PI), polyphenylene sulfide (PPS), ethylene (PE), nylon (PA), and polysulfone (PSF).

[0027] The anode of the magnesium fuel cell is metallic magnesium or a magnesium alloy;

[0028] Compared with the prior art, the metal-water battery of the present invention has the following advantages:

[0029] (1) The battery structure is simple. Only a transition layer and a regeneration liquid chamber are needed to eliminate single-cell products and eliminate maintenance during long-term discharge.

[0030] (2) Significantly improves the long-term feasibility of magnesium fuel cells. Attached Figure Description

[0031] Figure 1 Example 1: Schematic diagram of a single magnesium fuel cell structure.

[0032] Single cell casing, 2-magnesium anode, 3-air cathode, 4-electrolyte chamber, 5-transition layer, 6-regeneration chamber;

[0033] Figure 2 Example 1: Battery discharge curve.

[0034] Figure 3 Example 2: Battery discharge curve.

[0035] Figure 4 Example 3: Battery discharge curve.

[0036] Figure 5 Comparative Example 1: Battery discharge curve. Detailed Implementation

[0037] The structure used in the following embodiments of the present invention is as follows: Figure 1As shown, a single cell comprises a cathode, an anode, a transition layer, and a single cell casing. A transition layer is laterally disposed in the lower middle part of the hollow single cell casing. The four edges of the transition layer are sealed to the inner wall of the casing. The transition layer divides the casing into two non-communicating upper and lower chambers. The upper chamber is filled with electrolyte as an electrolyte chamber, and the lower chamber is filled with regenerated liquid as a regenerated liquid chamber. The anode and air cathode are placed in the electrolyte chamber.

[0038] AZ91 magnesium alloy is used as the anode, with an electrode size of 10mm*10mm*20mm (length*width*thickness). The cathode uses manganese oxide as the catalyst and nickel foam and carbon powder as the diffusion layer, with a cathode size of 10mm*10mm*2mm (length*width*thickness). The distance between the anode and cathode (set parallel to each other) is 5mm.

[0039] The cathode is composed of a hydrophobic diffusion layer, a current collection layer and a catalyst layer stacked in sequence. The catalyst layer is a manganese tetroxide catalyst, the current collection layer is a copper foam mesh, and the diffusion layer is a mixture of carbon powder and PTFE in a mass ratio of 9:1, which is then pressed together.

[0040] Example 1

[0041] The transition layer is a grafted copolymer hydrogel N,N-diethylacrylamide-co-dimethylaminoethyl methacrylate (P(DEA-co-DMAEMA)-gP(DEA-co-DMAEMA)) composite ion exchange membrane layer; wherein the grafted copolymer hydrogel (P(DEA-co-DMAEMA)-gP(DEA-co-DMAEMA)) is prepared as follows: 0.1100g of the macromolecular monomer N,N-diethylacrylamide-co-dimethylaminoethyl methacrylate P(DEA-co-DMAEMA), 0.03665g of monomer N,N-diethylacrylamide (DEA), 0.0321g of monomer dimethylaminoethyl methacrylate (DMAEMA), and 0.0 425g of crosslinking agent N,N'-methylenebisacrylamide (NNMBA) was dissolved in 7ml of deionized water to form a homogeneous and transparent solution. This solution was placed in a hard glass test tube with an inner diameter of 1.5cm and a height of 15cm for polymerization. After purging with nitrogen for 10min, 18mg of ammonium persulfate (APS) and 15μL of N,N,N',N'-tetramethylethylenediamine (TEMED) were added at room temperature (25℃) as initiators to initiate the polymerization reaction. After 24h, the gel was removed, cut into 2mm thick slices, and soaked in deionized water for 5 days, changing the water 4 times daily (every 6 hours) to remove unreacted monomers and low-molecular-weight sols. Then, a PVDF-SPEEK membrane was pressed tightly onto the outer (lower) surface. The membrane is a polyvinylidene fluoride-sulfonated polyether ether ketone blend membrane (PVDF to SPEEK mass ratio 4:1) in contact with acetic acid solution. The inner side (upper surface) is bonded with a PE-PP composite membrane (PE-PP: polyethylene and polypropylene blend membrane, 0.15 micrometer pore size; PE-PP mass ratio 4:1) in contact with the electrolyte. A layered transition layer material is formed, and the transition layer material is then heat-sealed to the inner wall of the shell. The transition layer material divides the shell into an upper electrolyte chamber and a lower regeneration liquid chamber.

[0042] When the pH concentration in the electrolyte chamber is greater than 6, the hydrogel in the transition layer swells and dissociates, H + The electrolyte is slowly released into the electrolyte chamber of the single cell. The electrolyte used in the single cell reaction is a 3.5% (w / w) sodium chloride aqueous solution. The single cell is reacted at 1 mA / cm². 2 During constant current discharge, record the discharge voltage curve of a single cell, such as... Figure 2 As shown, the discharge time lasted for 34 hours.

[0043] Example 2

[0044] The transition layer was prepared by combining poly(N,N-diethylacrylamide-co-N-hydroxymethylacrylamide) (P(DEA-co-NHMAA)) hydrogel with a porous PE membrane. The preparation method of P(DEA-co-NHMAA) was as follows: 0.042 g of N,N-diethylacrylamide (DEA), 0.1431 g of N-hydroxymethylacrylamide (NHMAA), and 0.0425 g of crosslinking agent N,N,N',N'-tetramethylethylenediamine (NNMBA) were dissolved in distilled water (7 ml). The solution was placed in a hard glass test tube with an inner diameter of 1.5 cm and a height of 10 cm for polymerization. Dry nitrogen (N2) was introduced for 10 min, and then 18 mg of ammonium persulfate (APS) and 15 μL of [unspecified chemical compound] were added at room temperature (25 °C). N,N,N',N'-Tetramethylethylenediamine (TEMED) was used as the initiator to initiate the polymerization reaction. After 24 hours, the gel was removed, cut into 2mm thick slices, and soaked in deionized water for 5 days. The water was changed 4 times a day (6 hours apart) to remove unreacted monomers and low-molecular-weight sols. Then, a PE film was pressed tightly onto the outer (lower) surface, and the PE film was heat-sealed around the edges to form a layered transition layer material. The transition layer material was then heat-sealed around the edges to the inner wall of the shell. The transition layer material divided the shell into an upper electrolyte chamber and a lower regeneration liquid chamber.

[0045] The regenerated solution is an acetic acid solution. When the temperature of the single cell exceeds 37°C, the hydrogel material in the transition layer shrinks, and the acid is slowly released into the electrolyte chamber of the single cell. The electrolyte used in the single cell reaction is a 3.5% sodium chloride aqueous solution. The single cell operates at a current of 1 mA / cm². 2 During constant current discharge, record the discharge voltage curve of a single cell, such as... Figure 3 As shown, the discharge time lasted for 38 hours.

[0046] Example 3: The transition layer is formed by mixing 10g of iron oxide colloidal particles, 10g of titanium dioxide colloidal particles, and 40g of polydimethylsiloxane (PMDS) monomer solution, and then carrying out a cross-linking reaction in a 1.5cm, 10cm high hard glass test tube to form a polymer and a transition layer. The transition layer is then hot-pressed and sealed to the inner wall of the shell. The transition layer material divides the shell into an upper electrolyte chamber and a lower regeneration chamber.

[0047] After the battery discharges, the negative electrode loses electrons, and the positive electrode gains electrons. The parallel positive and negative electrodes create an electric field in the electrolyte. Simultaneously, due to electron and ion migration, a circular magnetic field is formed in the battery according to the "right-hand rule." The applied electric and magnetic fields between the positive and negative electrodes can orient the particles in polydimethylsiloxane (PDMS). Acid is slowly released into the electrolyte chamber of the single cell. The electrolyte used in the single cell reaction is a 3.5% sodium chloride aqueous solution, and the regeneration solution is acetic acid. For the single cell, the current is 1 mA / cm². 2During constant current discharge, record the discharge voltage curve of a single cell, such as... Figure 4 As shown, the discharge time lasted for 40 hours.

[0048] Comparative Example 1: Figure 1 As shown, the single cell comprises a cathode, anode, transition layer, and a single-cell casing. AZ91 magnesium alloy is used as the anode, with electrode dimensions of 10mm*10mm*20mm. The cathode uses manganese oxide as the catalyst and nickel foam and carbon powder as the diffusion layer, with cathode dimensions of 10mm*10mm*2mm. The distance between the anode and cathode is 5mm. There is no transition layer. The electrolyte used in the single-cell reaction is a 3.5% sodium chloride aqueous solution. The single cell is subjected to an A / cm² flow rate of 1mA. 2 During constant current discharge, record the discharge voltage curve of a single cell, such as... Figure 4 As shown, the discharge time lasted for 25 hours.

Claims

1. A magnesium fuel cell, comprising a battery pack consisting of a single cell or two or more single cells connected in series, parallel, or a combination of series and parallel; characterized in that: The single battery includes a hollow single battery shell, and a transition layer is laterally arranged in the lower middle part of the single battery shell. The four edges of the transition layer are sealed to the inner wall of the shell. The transition layer divides the shell into two non-communicating upper and lower chambers. The upper chamber is filled with electrolyte as an electrolyte chamber, and the lower chamber is filled with regenerated liquid as a regenerated liquid chamber. The anode and air cathode are placed inside the electrolyte chamber; The transition layer is a grafted copolymer hydrogel N,N-diethylacrylamide-co-dimethylaminoethyl methacrylate composite ion exchange membrane layer, with a PVDF-SPEEK membrane pressed tightly onto the lower surface and a PE-PP composite membrane bonded to the upper surface. During battery discharge, as the pH value of the electrolyte chamber exceeds 6, the hydrogel in the transition layer swells. + Slowly released into the electrolyte chamber of the single cell. The regenerated solution is an acid solution.

2. The magnesium fuel cell according to claim 1, characterized in that: The regenerated solution is one or two of hydrochloric acid and acetic acid.

3. The magnesium fuel cell according to claim 1, characterized in that: The single battery casing material is made of one or more of the following: ABS plastic, polyvinyl chloride (PVC), high-density polyethylene (HDPE), polypropylene (PP), polyoxymethylene (POM), polyphenylene ether (PPO), polyimide (PI), polyphenylene sulfide (PPS), nylon (PA), and polysulfone (PSF).

4. The magnesium fuel cell according to claim 1, characterized in that: The electrolyte chamber is provided with a metal anode perpendicular to the bottom of the single battery casing, and air cathodes are placed on opposite sides of the battery casing and parallel to the metal anode. A transition layer perpendicular to the metal anode is provided below the metal anode.

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