All-Solid / Solid-Liquid Electrolyte Li-Ion Battery Innovation & Patent Review

Technology Assessment: Can an architecture that assigns dendrite suppression to a garnet ceramic separator and cathode wetting to a liquid catholyte hold the safety and cost case expected of a solid-state cell – and can high-temperature separator sintering be brought to automotive production economics? The chapter examines the trade-off between energy density and cycle life around the ≈300 Wh/kg level, the manufacturing chain from tape casting through accelerated sintering to surface finishing, and how public positioning compares with what the patent portfolio reveals about alternative catholyte routes.

Hybrid garnet-catholyte bilayer architecture – a lithium-stuffed garnet separator carries mechanical rigidity and stability against lithium metal while a liquid catholyte maintains low interfacial resistance at the cathode, spatially separating two requirements no single electrolyte material has met simultaneously, and enabling an anode-free cell in which lithium forms in situ. Phosphoric acid surface passivation of garnet – removal of residual lithium carbonate combined with incorporation of phosphate species holds area-specific resistance below 60 Ω·cm² after extended high-voltage exposure at elevated temperature, treating the separator surface as a distinct engineering layer rather than a bulk material property. Further concepts address cathode surface protection for high-nickel materials, photochemical removal of carbon contamination introduced during sintering, an alternative sulfide catholyte route, and green tape casting with accelerated sintering for separator production.

Tape casting, photochemical surface cleaning and phosphate passivation sharing one separator process window, alongside a cathode coating that serves either the liquid catholyte route or the sulfide alternative – aligning separator yield, interfacial resistance and cathode stability so energy density and cycle life advance together.