Lithium sulphur batteries (LSB) are a viable candidate for commercialisation among all post Li-ion battery technologies due 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 the 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 solvation of polysulphides turned out to be important for complete utilisation of sulphur, however this approach didn’t result in long term cycling. 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, stabilisation of lithium metal will have an impact on safety issues. Stabilised interface layer is important from the view of engineering of cathode composite and separator porosity, since this is an 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.