A hybrid electrolyte has been selected for its ability to provide both high ionic conductivity and long-term stability in lithium symmetrical configurations. Extensive research and development efforts were conducted to identify the optimal composition of this electrolyte, which was determined to consist of 80 wt% lithium thiophosphate (LPSCl) and 20 wt% lithium lanthanum zirconium oxide (LLZO). This particular ratio was chosen due to the complementary properties of the two materials: LPSCl offers high ionic conductivity, while LLZO contributes enhanced mechanical stability and resistance to degradation over repeated cycles. By leveraging the strengths of these two solid electrolyte materials, the hybrid electrolyte has demonstrated excellent performance in laboratory testing paired with Li metal. The stability of the electrolyte has been tested in conditions comparable with the dry room to validate the environment for the scale-up plant. In the integration in full cell configuration, different combinations and composition of the cathode have been evaluated to prove the advantages already shown during stripping-plating tests and compared with the pure sulfide as a reference. Structural change, interfacial reactions and phase formation have been studied by developing dedicated characterization techniques. Stability of the materials against different solvents, growth of the active material particles, changes at different state of charge, and effect of the processing route to the morphology of the NMC particles have been investigated to provide insights for the engineering of interfaces and components along the partners.
Arianna et al. (2026) studied this question.