A air-metal electrochemical cell is an electrochemical cell that uses anode made of pure metal and the external cathode of ambient air, usually with an aqueous or aprotic electrolyte. During the use of metal-air electrochemical cells, the oxygen reduction reaction occurs in the ambient air cathode while the metal anode is oxidized. The specific capacity and energy density of air-air electrochemical cells is higher than lithium-ion batteries, making it a prime candidate for use in electric vehicles. However, complications associated with metal anodes, catalysts, and electrolytes have impeded the development and implementation of metal-air batteries.
Video Metal-air electrochemical cell
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Lithium-air
The extremely high energy density of lithium metal (up to 3458 Wh/kg) inspires the design of lithium-water batteries. The lithium-air battery consists of a solid lithium electrode, an electrolyte that surrounds this electrode, and an oxygen-containing ambient air electrode. The current lithium-air battery can be divided into four subcategories based on the electrolyte used and the subsequent electrochemical cell architecture. This electrolyte category is aprotic, aqueous, aqueous/aprotic, and solid state, all of which offer their own advantages and disadvantages. Nevertheless, the efficiency of lithium water batteries is still limited by the incomplete discharges on the cathode, overpotential charging overpotential discharge, and component stability. During the release of lithium-water batteries, superoxide ions (O 2 - ) form will react with electrolytes or other cell components and will prevent the battery recharged.
Sodium-water
Sodium-air batteries are proposed in the hope of overcoming superoxide-related battery instabilities in lithium-water batteries. Sodium, with an energy density of 1605 Wh/kg, does not have high energy density levels such as lithium. However, it can form a stable superoxide (NaO 2 ) compared with superoxides that have adverse secondary reactions. Since NaO 2 will decompose backwards to the element component, this means that the sodium-water battery has an intrinsic capacity to recharge. Sodium-water batteries can only function with anhydrous electrolytes, aprotik. When the DMSO electrolyte is stabilized with sodium trifluoromethanesulfonyimide, the highest cycle stability of the sodium-water battery is obtained (150 cycles).
Potassium-air
Air potassium batteries are also proposed in the hope of overcoming the battery instability associated with superoxide in lithium-water batteries. While only 2-3 charge-discharge cycles have ever been reached with potassium-air batteries, they offer a very low overpotential difference of only 50 mV.
Zinc-air
Magnesium-air
Calcium-air
- No articles; see also Calcium: chemical properties for some air (oxygen) reactions. Aluminum-water
- Lithium-sulfur batteries
- High temperature metal air batteries
Iron-air
The iron-air refillable battery is an attractive technology with the potential of grid-scale energy storage. The main raw material of this technology is iron oxide (carat) is abundant, non-toxic, cheap and environmentally friendly. Most current batteries use iron oxide (mostly powders) to produce/store hydrogen through the Fe/FeO (redox) reduction/oxidation reaction (Fe H 2 ). In conjunction with this fuel cell it allows the system to behave as a rechargeable battery creating H 2 O/H 2 through production/electricity consumption. In addition, this technology has minimal environmental impact because it can be used to store energy from intermittent solar and wind power sources, developing energy systems with low carbon dioxide emissions.
The way the system works can be started by using the Fe/FeO redox reaction, the hydrogen created during the iron oxidation can be consumed by the fuel cell along with oxygen from the air to generate electricity. When electricity has to be stored, hydrogen generated from water by operating the fuel cell in reverse is consumed during the reduction of iron oxide to metallic iron. The combination of these two cycles is what makes the system operate as an air-iron rechargeable battery.
The limitations of this technology come from the materials used. Generally, bed bed oxide powder is selected, however, fast sintering and powder powder limit the ability to achieve high cycle counts resulting in lower capacity. Other methods, such as 3D-Printing and freeze casting, are currently under investigation seeking to allow the creation of architectural materials to allow for high surface area and volume changes during redox reactions.
Silicon-air
Maps Metal-air electrochemical cell
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Source of the article : Wikipedia
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