Solid-state Batteries (SSBs) offer a high-density, non-flammable alternative to the current lithium-ion battery technology, with lithium-stuffed garnet Li7La3Zr2O12 (LLZO) serving as a leading electrolyte candidate for solid-state electrolytes due to its high ionic conductivity and wide electrochemical window. This study finds the critical challenge in the development of LLZO ceramic electrolytes: The inherent trade-off between mechanical stability and ionic conductivity. The density of the electrolyte plays a pivotal role in modulating the lithium-ion flux and mechanical stress distribution. While porosity facilitates ion transport, it often compromises fracture resistance, increasing susceptibility to dendrite induced short circuits.  This study investigates microstructural design strategy using the fabrication of bi-layered LLZO pellets to enhance mechanical reliability without sacrificing electrochemical performance. The electrolytes were fabricated by uniaxially pressing LLZO powder at two distinct pressure levels (from a window of 60-300MPa) to create a density gradient, followed by high-temperature sintering of the pellets embedded in lithium-rich and pre-sintered mother powder bed to suppress lithium volatilization. Critical current density (CCD) and nanoindentation tests were conducted to characterize the interface of the sintered pellets. The dense-porous bilayer interface is proposed as a composite system that redirects lithium dendrite propagation and manages the internal lithium penetration stress. Furthermore, microstructural analysis reveals that the gradient-density structure alters fracture paths, potentially improving the overall toughness and dendrite resistance compared to homogeneous single-layered pellets. This investigation provides a strategy to optimize mechanical and electrochemical performance in next-generation ceramic electrolytes for high-performance SSBs.