In modern times, energy storage is an everyday obstacle. Keeping your phone, kindle, laptop, and even your car charged is a constant reminder of the way storing electrical charges efficiently and speedily is essential to our way of life. Activated carbon supercapacitors have been the middle ground between rechargeable batteries and electrolytic capacitors since their invention in the mid twentieth century. At their most basic, they consist of a metal plate known as a base with one side covered in activated carbon mixed with polyurethane (a glue-like material). A thin layer of electrolyte is then placed on top and another base with carbon is sandwiched to the other side. Their advantages lie in the way they store charge in the electric field, unlike batteries, which store charge in chemical reactions within the battery. Because of this difference, they can be charged very rapidly and do not wear out as chemical batteries do.
In this experiment, activated carbon supercapacitors were created from scratch using polyurethane, activated carbon phosphoric acid, and a few types of metal. The goal was to optimize energy storage within the supercapacitors and find which fabrication methods were best at storing charge. To that effect, several generations of capacitors were created using copper, brass, and aluminum bases, as well as different electrolyte acids within the capacitor. Ranging from totally unworkable prototypes to a whole farad of capacitance, each generation of capacitors worked better than the last.
The final generation of capacitors were constructed in order to test a hypothesis about the activated carbon layer. Five were made, with two having a higher concentration of activated carbon and three having a lower concentration; after being made, one of the higher and one of the lower concentration were sprinkled with larger grain carbon to increase surface area and contact with the electrolyte. The capacitor with higher concentration of activated carbon and sprinkles was found to have the highest capacitance.
This finding allows us to make more efficient energy storage methods that could be used to replace batteries in the future. It also demonstrates that we can replace harmful components of electrical systems with readily available and ecologically friendly components and cause less destruction of the earth.
Noah Foster-Frau, ’17
Physics & Engineering