Self-Charging Power Cell Stores What it GeneratesCategory: Science & Technology
Posted: August 21, 2012 05:59PM
For most energy systems currently in use, the energy is generated in by one device and stored by another, like a solar cell and a battery. While this approach has worked well for a very long time, requiring two separate systems can increase the size and complexity of devices. Now researchers at the Georgia Institute of Technology have created a hybrid energy device that generates and stores electrical energy on its own.
Batteries store energy by creating ions at the electrodes. At the anode the ions are negatively charged, while the cathode has positively charged ions. This charge differential makes the electrons want to flow from the anode to the cathode, as soon as there is an electrical connection. (There is also a salt bridge that connects the solutions the anode and cathode are in, to maintain equilibrium between the solutions.) In the hybrid cell the researchers made, a piezoelectric membrane creates an electric field which drives lithium ions toward the anode, to create the differential and chemically store the energy. Piezoelectric materials connect electrical and mechanical forces, so physically deforming the membrane, by stepping on it for example, will charge the cell.
Currently the hybrid cells the researchers built have a storage capacity of just 0.036 millamp-hours, which is not very much, but it can be, the researchers theorize, five times more efficient than modern methods of converting mechanical energy to chemical energy that require two devices. The researchers believe they can increase the efficiency even more though by replacing the steel shell currently used with something that absorbs less mechanical energy.