A new battery concept could enable electric vehicles to reach ranges of up to 1,000km. Developed by the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden, Germany, the EMBATT system transfers bipolar principles used in fuel cells to lithium batteries.
“We use our expertise in ceramic technologies to design the electrodes in such a way that they need as little space as possible, save a lot of energy, are easy to manufacture and have a long life,” explained Dr Mareike Wolter, project manager at Fraunhofer IKTS.
The concept is designed to address a few key problems that traditional battery systems face. Depending on the model, electric cars are equipped with hundreds to thousands of separate battery cells. Each of these cells is surrounded by a housing, which connects to the car with terminals and cables, and monitored by sensors.
The issue stems from the fact that the housing and contacting take up more than 50% of the space, meaning that the ideal of densely packed cells is unachievable. Additionally, electrical resistance, which reduces the power, is generated at the connections of the small-scale cells. However, the EMBATT system significantly reduces or eliminates these problems by a seemingly simple method.
Using the bipolar principle applied to fuel cells, individual battery cells are not strung separately side-by-side in small sections; instead, they are stacked directly one above the other across a large area. Doing so entirely removes the structure for housing and contacting, allowing far more batteries to fit into the car.
Furthermore, the direct connection of the stacked batteries allows current to flow over the entire surface of the battery. Doing so considerably reduces any electrical resistance and is largely helped by the batteries’ electrodes, which are designed to release and absorb energy very quickly.
The principle component of the battery is the bipolar electrode – a metallic tape that is coated on both sides with ceramic storage materials. One side of the tape operates as the cathode, the other as the anode. It is this electrode that functions as the heart of the battery to store energy.
The electrode is in no small part the result of the researcher’s expertise in ceramics, using ceramic materials as powders that are then mixed with polymers and electrically conductive materials to form a suspension. This suspension is then applied to the tape in a roll-to-roll process.
“This formulation has to be specially developed – adapted for the front and back of the tape, respectively,” Wolter explained. “One of the core competencies of our institute is to adapt ceramic materials from the laboratory to a pilot scale and to reproduce them reliably”.
Going forward, the researchers plan to develop even larger battery cells and work on installing them into electric vehicles. They and their partners are aiming for initial vehicle tests in 2020.