Future generation batteries only become feasible for electromobility applications by development of new energy storage concepts in terms of materials and cell chemistry and by addressing the challenging tasks connected to the requirements of the automotive industry at the same time. Energy and power density, costs, safety and lifetime are the most important and impacting criteria for energy storage development. Most significantly the energy density of a battery determines the maximum autonomic driving distance of an electric car and strongly limits the broad replacement of fuel driven vehicles until now.
One promising approach to significantly enhance the energy density of state-of-the-art lithium ion batteries is the lithium sulfur system. Sulfur as the active cathode material has a theoretical specific capacity of 1672 mAh g-1 and an average discharge potential of 2.2 V versus lithium. While for lithium ion batteries using intercalation cathodes a limit in energy density of about 200 Wh kg-1 is expected, for the lithium sulfur battery energy densities of up to 600 Wh kg-1 might be achievable. Furthermore cost reduction and safety increase are attractive features since sulfur is widely available, less expensive and less toxic when compared to conventional cathodes. However, various challenges are connected to the lithium sulfur cell chemistry, which need to be solved within systematic studies and by the development of new material concepts.
In this proposed project these challenges will be addressed and a lithium sulfur battery with significantly improved properties is targeted. Key aspects are:
- Carbon materials with defined pore structure in the nanometer regime as conductive and stabilizing framework for the sulfur cathodes
- Polymer electrolytes and electrolyte additives to reduce / suppress the "shuttle" mechanism
- Coating of lithium anodes to reduce the dendrite formation and electrolyte depletion
Besides fundamental studies on mechanisms and material research, the project aims for a potentially fast transfer of the results to industrial realization.
Fraunhofer Institute for Material and Beam Technology IWS
