Sustainable energy storage with high-voltage batteries
Cruising range is one of the greatest challenges for the rapid implementation of electromobility in Europe.
Ten partners from industry and research organizations now join forces in the EU funded project ECO COM’BAT, coordinated by the Fraunhofer Project Group Materials Recycling and Resource Strategies, part of the Fraunhofer Institute for Silicate Research ISC, to develop the next generation of lithium-ion batteries – the high-voltage battery. Better performance is not the only goal for the new battery. Compared to conventional batteries the new type should be more powerful and with regard to the materials used even more sustainable. The main task here is the substitution of conventional, often expensive, rare or even critical materials.
Lithium-ion batteries are the preferred source of energy for electric vehicles and consumer devices owing to their high energy density and reliability. But expectations rise with green car sales and consumer devices grow more and more complex. Consumers ask a lot from a new battery: better safety, longer life spans, higher energy density, better performance and wider range.
The scientists teaming up in the project ECO COM’BAT („Ecological Composites for High-Efficient Li-Ion Batteries“) set out to develop a novel type of high-voltage battery. Their goal is to extend the range of electric vehicles, to shorten charging times, to reduce battery weight, to enhance stability and durability, and above all, to substitute critical or precious raw materials commonly used in conventional lithium-ion batteries.
Upscaling to production scale
In order to achieve all this at the same time, the project partners use innovative materials: low-cobalt NMC – short for lithium nickel manganese cobalt oxide – serves as active electrode material. It provides the required energy density but contains approx. 20 percent less cobalt than conventional solutions. Carbon nanotubes and porous carbon serve as conductive additives. They enhance the electrical conductivity of the electrodes and allow high energy densities. A special high-voltage electrolyte based on the conductive salt lithium-bis(fluorosulfonyl)imide (LiFSI) serves as electrolyte which can be operated stably even at high voltages. An ion-conductive hybrid polymer coating protects the electrolyte materials and ensures safe and reliable use of the battery and a long lifespan.
The first task for the ECO COM’BAT team will be the upscaling of the processes required for the large-scale production of the new battery materials. The next step will then be the upscaling of the actual cell production to close-to-industry pilot scale and then to production scale. The challenge is to meet automotive standard requirements with energy and cost efficient production methods.
Efficient gentle recycling
A more widespread use of electric vehicles will invariably mean more waste batteries. To prevent problematic waste and also to recover precious materials like graphite, cobalt and lithium, new strategies must be developed to ensure efficient recycling. This begins with a design for recycling that allows to recover the contained materials to the best possible extent. To this effect, the researchers will also test innovative recycling processes.
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