Porous Garnet Bilayer Electrolyte for Stable Lithium Metal Interfaces

The patent introduces a porous layer within the garnet electrolyte structure that can accommodate volume changes of the lithium metal anode during plating and stripping cycles. This porous structure provides void space to absorb expansion and prevents interface void formation and dendrite penetration, thereby maintaining interface stability while enabling the use of thin dense electrolyte layers for high energy density.

The patent creates a composite garnet electrolyte structure combining dense regions (for high ionic conductivity and energy density) with porous regions (for mechanical compliance and dendrite inhibition). This composite architecture integrates the advantages of both dense and porous structures, achieving high volumetric energy density while preventing interface instability and dendrite formation.

The porous layer acts as a physical barrier and stress-distributing structure that prevents dendrites from penetrating through the thin dense electrolyte. The porous structure disperses local stress concentrations that would otherwise lead to dendrite formation and penetration, enabling the use of thinner electrolyte layers without increasing susceptibility to dendrite attack.

The patent introduces a third dimension (porosity) into the electrolyte structure, creating a hierarchical architecture where the porous phase provides a buffer zone that dendrites must navigate through, effectively increasing the tortuous path and reducing penetration susceptibility despite the overall thinness of the electrolyte layer.

The porous structure is incorporated into the electrolyte fabrication process itself, rather than being added as a separate component. The pore-forming agents are mixed into the garnet precursor slurry before tape casting and sintering, allowing the porous-dense bilayer structure to be formed in a single integrated manufacturing process, thereby minimizing process complexity while achieving dendrite resistance.

The patent creates a composite structure where porous and dense phases are formed simultaneously during a single sintering process. By incorporating pore-forming agents into the garnet precursor mixture and using controlled sintering conditions, the complex bilayer structure is achieved in one step rather than requiring multiple separate fabrication and assembly operations.