Zinc-air batteries are metal-air batteries powered by zinc oxidation and oxygen reduction. A battery is a device that produce electricity based on a redox chemical - reaction. A redox reaction happens when a compound oxidizes (losing electrons) and another compound reduces (gaining electrons). When the oxidizing compound and the reduction compound are separated the reaction has an electrochemical progress. The electrons move from a lower potential place to an higher potential one. For an electron (negative charge) higher potential means lower energy. Lower energy means higher stability and the reaction proceeds spontaneously. The moving electrons from the anode (-) to the catode (+) can be used to produce electrical work. I’m going to use this principle to light up a LED.
The electrochemistry beyond its working is the following: Steel catalyzes the reduction of oxygen to hydroxide (Cathode); Zinc anode is oxidized by hydroxide to zincate ion. Cathode and anode must be separated to avoid battery shortcut.
The electrolyte usually consists of a sodium hydroxide solution. Hydroxide’s ions formed by the salt boost the reaction and ensure the balance of charges. I’m using a concentrated sodium carbonate soution, which is not as aggressive as a sodium hydroxide’s one, but it still produces hydroxides and allows the reaction to appreciably progress.
Zincate ion is water soluble: that’s an important property. It allows the reaction to proceed. In Aluminum-air batteries for example, aluminum is oxidized to aluminum oxide Al2O3, which is insoluble in water. It forms a film over the aluminum anode, that inhibits the progress of the reaction.
First misurations reported an incrementing voltage (as the reaction was improving). Maximum voltage reported is 2.40V, approximately 800mV each cell. Not the most efficient zinc-air battery, but enough powerful to light up a simple LED.
Recorded with a NIKON D7500 Digital Camera, DX SWM VR ED IF Aspherical 72 , Edited with Camtasia 9.
Disclaimer: The following process is shown only for demonstration and entertainment purposes. It should not be replicated without proper knowledge.
21 фев 2020
