#video on #jugaad #aluminum-air #batteries #toread
on 02026-08-24another #video #toread about aluminum-foil #batteries by #Thoisoi, who turns out to be Polish or Estonian, not Russian. He uses stainless-steel window screens as the cathode current collector, because it’s an #aluminum-air battery; in one case he adds a layer of graphite conductive spray paint to the screen. Additionally he’s going to use activated carbon for the cathode, sprinkling it on the epoxy-coated graphite-coated fine stainless-steel mesh, then pressing it in a jugaad five-tonne hydraulic press at 100° for 40 minutes, though he says you could just leave it for 12 hours at room temperature. In the end he has eight cathodes, four with a coarser mesh; the dry cathodes measure as only 8Ω or so on a non-autoranging multimeter. He’s making pouch cells with a food-bag hot sealer, which melts sheets of polyethylene (LDPE) together with a hot wire. His anode is 8-layer-thick aluminum foil. As an electrode separator, he uses a wet paper towel, and sandwiches the anode between two cathodes, I suppose to keep air from getting to it. Weirdly, he seals the pouch cell in plastic, so I’m not sure how the air is going to get to the cathodes. One of the cells uses 20mℓ o an electrolyte made from 5g NaCl and 5g NaHCO₃ #materials in 100mℓ of water, giving 0.75V which rapidly declines. On injecting 10mℓ 10% NaOH into the bag with a syringe, it perks up to 1.6V. Short-circuit current is 750mA, but he needs two in series (measuring 2.60V on the multimeters) to dimly light a red LED, suggesting an “internal resistance” of hundreds of ohms. With the NaOH he thinks its shelf life is only a few hours; his batteries were dead in four hours of playing his CD player.
I thought he was going to explain the results he got from different cathode geometries, but he never does. Also he never reports the power output of the battery or explains how the air is supposed to get in.
on 02026-01-14#video about #Mr-Electron #manufacturing #aluminum-air #batteries with a carbon brush from a motor as the cathode in a potassium hydroxide electrolyte, or some bent-up baling wire. He’s hacksawing the top off a lead-acid battery case from an old motorbike and gets an open-circuit voltage of about 1.6 volts and a short-circuit current that’s initially 20mA with an aluminum-foil anode; when he replaces the carbon-brush cathode with the bent-up baling wire this jumps to 40–80mA. #hoarding #electronics #energy #toread
on 02024-10-18#video about #manufacturing #aluminum-air #batteries with #3D-printing ABS. He says potassium hydroxide will eat PLA, which makes sense but which I hadn’t realized. #Mr-Electron here is using steel baling wire for his cathodes. For his anode he cuts up thick aluminum sheet metal with shears and then presses it flat in a vise. Each aluminum anode plate is crimped onto baling wire from the following cell in the battery using a hammer and anvil. He gets 10.2V open-circuit voltage from 8 series cells. I’m unclear how air is supposed to get to his cathodes. He does some load testing with small electric motors but doesn’t actually measure the current. The short-circuit current he measures is 160mA and rapidly dropping. After testing with LEDs for a while the open-circuit voltage has dropped to 3.8 volts. Later he cuts cathode forms out of CDs with an angle grinder and cutoff disc, wrapping them tightly with baling wire to maximize area. His higher-current anodes are aluminum-foil-wrapped popsicle sticks, dimensioned to fit inside the battery compartments, but for whatever reason he didn’t install the plates parallel, resulting in a dramatically unnecessarily high internal battery resistance, which he doesn’t bother to measure, but he gets 240mA out of it. His connections to the aluminum plates are made by torquing a pringled steel washer down onto their non-submerged ends with a bolt. The 6 cells in series ought to give about 9.6 volts open-circuit, but instead he gets only 4.8V (0.8V per cell), which he blames on residual sulfuric acid contamination, but commenter “gsestream” suggests might be due to a lack of oxygen. He uses a DFRobot USB boost converter to charge his cellphone. #bootstrapping #scouting #jugaad
on 02024-10-18#video about #manufacturing #aluminum-air #batteries with either KOH or NaCl electrolytes. #energy #electrolysis Unfortunately “members only”.
on 02024-06-25#video about #manufacturing #aluminum-air #batteries with dual electrolytes: potassium hydroxide and 50% H₂SO₄, separated by a membrane, to get a higher voltage, over 2 volts. Uses “activated carbon felt” (??) for the air electrode. With a single electrolyte he gets 1.56V. He suggests bleach as an alternative alkaline electrolyte and vinegar as an alternative acid. He uses paper towels to hold the electrolytes in place. For “some short testing” he uses baking paper as the membrane, but of course it won’t last long in that environment! He suggests Nafion as the only viable membrane option. His postage-stamp-sized test cell gets 2.2 volts and can light an LED. He adds MnO₂ to his graphite electrode as, I think, a depolarizer, boosting the cell to 2.5V. (Maybe it’s an actual electrolyte material, though?). For whatever reason he never measures its short-circuit current, except for showing that the LED lights and doesn’t immediately burn out, so the battery presumably has on the order of 100Ω of equivalent resistance. Finally he builds a version of the battery with a salt bridge instead of a membrane, but using zinc rather than aluminum. Surprisingly the salt-bridge version is also able to light the LED, despite presumably having much higher ESR. #energy #electrolysis
on 02024-06-25