Introduction: DIY Rechargeable D-Cell Battery From Aluminum Foil

There are enough of tutorials online showing how to make homemade batteries. Sadly, most DIY batteries either accept no practical use or come up with a multifariousness of hazards or complex demands. Lemon and potatoes batteries are generally incredibly weak and crave perishable organic found material every bit a starting point; home-brew pb-acid batteries are based on highly toxic and corrosive chemicals; and most other batteries types normally require strange chemicals like activated carbon or manganese dioxide. Well not this battery!

This battery is made from incredibly simple materials available in most homes and has enough power to run a multifariousness of devices, specially when scaled up! This makes information technology an excellent emergency source of electricity when traditional batteries aren't available. Additionally, this blueprint can exist easily recharged with almost whatever directly current source, is remarkably lightweight, and, unlike the more common aluminum-air batteries, doesn't require airflow to run. And so what are nosotros waiting for? Let'south get started!

Stride ane: Gather the Supplies!

For this project, you will need the following items:

  • Aluminum foil
  • Salt (potassium, calcium, or sodium chloride will work, while bicarbonates, carbonates, and hydroxides won't)
  • A source of a less reactive metal (tin cans or copper wire/tubing are both splendid options)
  • Paper (writing newspaper, paper towel, and toilet paper are all viable materials)
  • PVA gum (I'm using Gorilla woods glue)
  • Water

These next few items are optional, but nonetheless recommended:

  • ane" PVC pipage department (this will be the housing for the bombardment)
  • Hot gum gun (for associates)
  • A multimeter (for testing)

Step 2: Design and Theory

All batteries are based on a blazon of chemical reaction known as a redox reaction (short for reduction-oxidation reaction). In a redox reaction, one substance is oxidized (loses an electron) while another is reduced (gains an electron). Pretty elementary, correct? It turns out when you separate this type of chemic reaction into two halves, you can channel the electrons that the substances substitution through a conductor and apply them as electricity before they render and consummate the redox reaction.

In this aluminum-metal bombardment, the ii halves of the bombardment are soaked in a saline solution and separated past a special membrane that merely allows sodium and chloride ions through. The aluminum on one half wants to be oxidized into solution as aluminum ions, while the copper or steel on the opposite side wants to remain out of solution equally a pure metal. If the copper (or steel) side contains copper or fe ions in solution, the redox reaction volition brainstorm. The aluminum on one one-half of the cell will give up some of its electrons to get into solution, and the copper or steel on the other side volition use upwards the electrons to convert the copper or atomic number 26 ions in solution dorsum into metallic copper or atomic number 26. The membrane in between the two halves allows electrons and carrier ions like sodium and chlorine to menstruation and balance, while keeping the copper/iron electrons away from the metallic aluminum. If the copper or fe ions make contact with the aluminum, they will exist directly reduced dorsum into copper or fe metal, and no ability will menstruum from the battery.

When the bombardment is charged, the positive final of the DC supply is connected to the anode and the negative to the cathode. As voltage is applied, chloride ions from the solution are attracted to the anode. The copper (or iron) reacts with the chloride ions to class copper or fe chlorides, which readily dissolve into solution. This finer recharges the cell, making information technology set up for another electricity-producing redox reaction cycle. Nonetheless, unlike the copper or iron which is rejuvenated upon recharging, the aluminum in solution at the cathode is far too reactive to revert back into aluminum metal when the battery is charged. Instead, it will exist slowly corroded away into aluminum oxides and hydroxides (as well as sodium aluminate).

Stride 3: Brand the Anode

The anode will be the positive side of the battery, and must exist made of some metal that is less electronegative than aluminum. Copper, iron, and steel are all expert candidates, due to their high abundance, although copper seems to work the best. You lot may be tempted to use a less reactive metal like pb or silver, but they won't perform nearly too due to the poor solubility of their chlorides. I personally used a short length of copper pipe that I wrapped into a cylindrical shape. In the images above, I likewise showed that an ordinary steel tin can may also be turned into a functional anode. Since this is meant to be a D-sized battery, I cut the anode material downward to the height of an ordinary D-cell. The diameter was slightly smaller than the inside bore of the PVC pipe section I later used to house the battery cell.

Step four: Brand the Ion-Exchange Membrane

To make the earth-shaking ion-exchange membrane, just wrap the anode you lot just made in paper or another thin, absorptive material. So, soak the whole unit of measurement in table salt water. If you don't wish to use ordinary salt, you may also endeavor non-sodium salt (potassium chloride) or another alkali metal chloride, nitrate, or sulfate. Calcium and magnesium salts won't work besides, and bicarbonates, carbonates, and hydroxides should be avoided since copper and fe compounds with these ions are more often than not insoluble.

After soaking, coat the unabridged paper portion with ordinary PVA glue (Elmer's school mucilage and nigh white glues are expert examples of PVA glue). This volition stop about of the soluble copper/atomic number 26 salts from migrating to the cathode side of the bombardment, where they would readily react away without producing any usable electricity. It is best if the mucilage is allowed to dry (at least most of the mode). If you exit the glue out to dry, make sure you re-saturate the membrane with saltwater after. A quicker route to curing the gum that I establish was dipping the glue-coated membrane into a solution of sodium tetraborate (borax), which near immediately polymerizes the PVA gum and helps increase its ion electrical conductivity.

Pace 5: Wrap on the Aluminum Foil Cathode

As mentioned previously, the other essential half of this battery is its aluminum cathode. This could be by far the simplest step: only wrap the ion exchange membrane in aluminum foil and you're proficient to go! Just be sure the aluminum foil doesn't brand contact with the copper or steel anode!

Step vi: Enclose the Battery (optional)

While the battery itself is washed, information technology'due south unlikely that you want a dripping-moisture, somewhat delicate battery laying around in the open. My personal solution: stick the whole thing an a department of ordinary PVC tubing. I used PVC pipage with a 1" (25mm) inner diameter and a i.25" (31mm) outer bore similar to a commercial D-size battery. I sealed the bottom and most of the acme with hot glue, making sure to exit some of the foil cathode and metallic anode exposed. I didn't fully seal the battery, since pocket-sized amounts of gas tend to be formed during the charging process.

Footstep 7: Examination Information technology Out!

You're finally washed! Now, to enjoy the fruits of your labor! Without a supply of soluble iron or copper salts on the anode side, this battery will not work, and then charging the bombardment is our first step. You can use most any DC current source, as long as the current isn't besides loftier (5A seems to exist the condom maximum). To charge the battery, simply connect the anode to the supply positive and the cathode to supply negative. If yous're monitoring the current during charging, you'll probably detect it starts to decrease as the bombardment gains accuse, which is a skillful sign that the bombardment is working properly. Later charging, you may want to test the battery with a multimeter. Using a copper anode, I got a maximum voltage of 1.44V across my DIY bombardment subsequently a pocket-size charging wheel. The highest electric current I got from the bombardment was a whopping 1.2 amps. While this may not sound like a whole lot, this is actually infrequent for a homemade battery. For comparison, traditional lemon or potato batteries typically output just a few milliamps at best. A commercial D-jail cell battery can output over v amps of current, so this homemade battery is roughly equivalent to a moderately-used D-cell!

Although it is not shown here, I did a test in which I pitted my bombardment against a true 1.5V D-cell. Both batteries were used to bulldoze a small DC motor while the input currents and motor speeds were recorded. In the end, this homemade bombardment performed the Exact SAME every bit the commercial D-cell in this test! Great for aluminum foil, scrap metal, and salty mucilage-paper!

This battery is past no means perfect. The ion substitution membrane still allows some soluble copper salts through to the cathode side of the battery, where they react away into copper metal and insoluble copper oxides and hydroxides. Additionally, the aluminum cathode gradually deteriorates due to the caustic atmospheric condition in that one-half of the cell. While there is room for comeback, this battery is still very usable, and can be easily congenital and used by people in desperate need of electricity. By scaling this bombardment up and adding multiple cells in series and parallel, a very large corporeality of power could be produced or stored for little to no price. The potential for this engineering science could be immense, especially if information technology is further adult. Who knows...maybe you'll exist the i to develop it!

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