With potassium hydroxide electrolyte the 1.2 volts is produced with salt. (The reaction improves if it is done in a basic solution that supplies excess OH – ions. The balanced equation is 4Al + 3O 2 + 6H 2O → 4Al(OH) 3 + 2.71 V.The cathode reduction half-reaction is O 2 + 2H 2O + 4e − → 4OH − +0.40 V.The anode oxidation half-reaction is Al + 3OH − → Al(OH) 3 + 3e − −2.31 V.The reaction rate can be increased by adding additional hydroxide ions using baking soda (NaHCO 3 ) or strong base (NaOH or KOH). The salt water solution is an electrolyte which carries the charged ions from one electrode to the other. Crushed charcoal acts as a catalyst and greatly increases the surface area where the reactions can occur. Copper is used to collect the electrical current and is not consumed in the reaction. The oxygen, O 2, from air is reduced to produce hydroxide ions, OH –. The aluminum metal, Al, is completely reacted to produce aluminum hydroxide, Al(OH) 3. The aluminum air battery is a primary cell because the cell ingredients are consumed and the battery therefore cannot be recharged. A galvanic cell generates electrical currents via spontaneous redox reactions in the cell. The batteries use the oxidation of aluminum at the anode and the reduction of oxygen at the cathode to form a galvanic cell. Aluminum air batteries are part of a larger category of batteries, metal air electrochemical batteries, wherein the pure metal forms the anode and the external air is the cathode. Another set performance matrix that is commonly used together with energy densities is power densities, which is the amount of energy densities available every second of time (in units of Watt/kilogram and Watt/Liter). Energy densities are often used to evaluate the performance of a battery. Energy densities are the amount of total energy output by a battery divided by the battery weight or the battery volume in units of Watt-hour/kilogram or Watt-hour/Liter. Aluminum air batteries offer one of the highest energy densities of all batteries because the weight of air is very light compared to other types of battery electrode materials. In this experiment, we will learn about one kind of single-use battery, an aluminum air battery.Īluminum air batteries use aluminum metal and the oxygen in the atmosphere as their electrodes. For example, cell phone batteries are rechargeable (e.g., we have to plug our phones in each night), however the batteries we put into our TV remotes and flashlights could be rechargeable and single use. Depending on the specific electrochemical reaction that takes place inside batteries, batteries may be either single-use (primary cell) or rechargeable (secondary cell). Batteries store chemical potential energy which can be released to produce electrical energy, or electricity.
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