Periodic Reporting for period 3 - HELIS (High energy lithium sulphur cells and batteries)
Reporting period: 2018-02-01 to 2019-05-31
The HELIS project has been addressing remaining issues connected with a stability of lithium anode during cycling, with the engineering of complete cell and with questions about lithium sulphur batteries cells implementation into commercial products (aging, 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. The stabilized 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 lithium sulphur batteries aging can determine the practical applicability of LSB in different applications, but the project is aiming towards the development of three different series of Li-S cell prototypes, all of which will be tested according to specifications for automotive use.
The Li-S battery technology in HELIS project is based on low-cost cathode materials. The cost for electrolyte, binder, and separator costs are estimated to be similar to those in the current Li-ion battery technology. The use of a much cheaper cathode will be maintaining low cost of Li-S cells and the final cell price is estimated to be below 150 €/kWh. By achieving 500 Wh/kg energy density this will substantially improve the driving range, thus having a positive impact on EV acceptance.
Patent application co-owned by NIC and SAFT is in the process of filling. We accumulated also additional foreground on the field of lithium protection, electrolyte formulation, separator fabrication, binders, recycling and modelling which will be used in the future for further optimization of this or any other battery technology.
The abruptive change in the selection of the materials (cathode composite and electrolyte composition) enabled us to obtain cells with high energy density which can be cycled with high Coloumbic efficiency and have no safety issues. After the development of industrial viable lithium metal protection, this approach will be ready for further development to higher TRL’s.