Powercaps: New ways of recovering energy in industrial environments
Today, most electric energy is stored mostly in batteries or capacitors. However, both are not ideal for many applications in the industry. A battery can store large amounts of energy and store them over longer periods, but it takes a long time to charge them. Plus, the work live of a battery and the number of charging cycles both are limited. A capacitor, in contrast, accommodates the energy quickly and has a long life, but it lacks the storage capacity and period of a battery.
In the project FastStorage BW II, researchers from the Karlsruher Institut für Technology (KIT) are working on a solution that meets both requirements. They are aiming at a hybrid system has the advantages of both battery and capacitor but none of their drawbacks. These powercaps are made of two large-sized electrodes. In contrast to conventional capacitors the electrodes are not symmetrical, and instead of a dielectric, the gap between the electrodes is filled with an electrolyte that provides positive ions. Similar to a battery, one electrode is made of metal oxides which are subject to a redox process. The second electrode resembles a capacitor in that it is made of carbon materials. Unlike a battery however the energy is not stored through a chemical reaction, but instead in the electric field between positive ions and electrons. The redox-active material in the capacitor increase both voltage and field density which leads to a disproportional increase of the device’s capacity. Therefore, powercaps can store about twice as much energy as a conventional capacitor, and they can provide up to ten times more energy than a battery, at least in theory.
The KIT is performing the tasks of developing, building and testing the storage prototypes for the powercap cells. The scientists are investigating how the storage modules can be welded in a semi-automatic process by robots. During this process, welding parameters and working speed are optimised. In addition, they develop a packaging concept that ensures a homogeneous thermal cell load and cooling. The development of an adequate electronic operational control that guarantees the safe and economic operation of the module will be pivotal.
The researchers intend to test their first prototypes in intra-logistics applications, like electric storage and retrieval machines, forklifts and autonomous transport systems. “During each and every lifting and braking action, it is possible to regain electric energy that can be stored in the powercap”, says Thorsten Grün who oversees the FastStorage BW II project. In such applications, powercaps can make energy recovery solutions more efficient or make them possible in the first place. As a welcome side-effect, powercaps could significantly reduce the charging time of electric transport vehicles.
Possible application fields extend to all activities in which a varying energy demand needs to be met. For instance, the novel storage elements could be used in uninterruptible power supplies or in circuitry that controls the frequency in the power grid
More information: https://www.competence-e.kit.edu/