Two commonly discarded metals were used by Vanderbilt University researchers to create a novel steel-brass battery. The device is based on junkyard metal scraps and can store energy at levels comparable to lead-acid batteries while charging and discharging at rates comparable to ultra-fast charging supercapacitors.

Junkyard battery powers a light. Image source: Vanderbilt Univ.Junkyard battery powers a light. Image source: Vanderbilt Univ.The researchers say one key is to anodize the metals in a chemical process used to give aluminum a durable, decorative finish. Anodizing the waste scraps with a common household chemical and residential electrical current restructures the metal surfaces into nanometer-sized networks of metal oxide. These can store and release energy when reacting with a water-based liquid electrolyte.

This phenomenon accounts for the fast charging behavior and stability observed. After testing the battery for 5,000 consecutive charging cycles – the equivalent of more than 13 years of daily charging/discharging -- it retained more than 90% of its capacity, the researchers say. The battery uses non-flammable water electrolytes that contain potassium hydroxide, a salt used in common laundry detergent.

The “Baghdad Battery,” a device dating from the first century BC and considered by some to be the world’s oldest battery, was the inspiration behind the research. It consisted of a ceramic terracotta pot, a copper sheet, and an iron rod, which were found along with traces of electrolyte. Although this interpretation of the artifacts remains controversial, the way they were constructed influenced the Vanderbilt research team’s design.

The next goal is to build a full-scale prototype battery suitable for use in energy-efficient smart homes.

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