HELIS

Thanks to their high theoretical energy density and cost-effectiveness, lithium-sulfur batteries (LSBs) are viable candidates for commercialization among all post-Li-ion battery technologies. But despite our best efforts, there are still problems to be solved… Some technological aspects, such as the development of host matrices, the interactions of the host matrix with polysulfides and the interactions between sulfur and electrolyte, have been successfully developed as part of the Eurolis project. The open porosity of the cathode, the interactions between host matrices and polysulfides, and the appropriate solvation of polysulfides all proved important for the full utilization of sulfur.We have also shown that effective electrode separation enables stable cycling with excellent coulombic efficiency. The remaining questions are mainly related to the stability of the lithium anode during cycling, the engineering of the complete cell and issues concerning the implementation of LSB cells in commercial products (ageing, safety, recycling, batteries). The instability of lithium metal in most conventional electrolytes and the formation of dendrites due to the uneven distribution of lithium during deposition are at the root of several safety problems, directly attributable to dendrites and low coulombic efficiency due to a constant increase in internal resistance linked to electrolyte degradation. Stabilizing the lithium metal and the interface layer will therefore have a major impact.