HELIS

Lithium sulphur batteries (LSB) are viable candidates for commercialization among all post Li-ion battery technologies thanks to their high theoretical energy density and cost effectiveness. Despites many efforts, there are remaining issues that need to be solved and this will provide final direction of LSB technological development. Some of technological aspects, like development of host matrices, interactions of host matrix with polysulphides and interactions between sulphur and electrolyte have been successfully developed within Eurolis project. Open porosity of the cathode, interactions between host matrices and polysulphides and proper solvatation of polysulphides turned to be important for complete utilization of sulphur. Additionally we showed that effective separation between electrodes enables stable cycling with excellent coulombic efficiency. The remaining issues are mainly connected with a stability of lithium anode during cycling, with engineering of complete cell and with questions about LSB cells implementation into commercial products (ageing, safety, recycling, battery packs).

Instability of lithium metal in most of conventional electrolytes and formation of dendrites due to uneven distribution of lithium upon the deposition cause several difficulties. Safety problems connected with dendrites and low coulombic efficiency with a constant increase of inner resistance due to electrolyte degradation represent main technological challenges.

From this point of view, stabilization of lithium metal will have an impact on safety issues. Stabilized interface layer is important in view of engineering of cathode composite and separator porosity since this is important parameter for electrolyte accommodation and volume expansion adjustment. Finally the mechanism of LSB ageing can determine the practical applicability of LSB in different applications.