[en] Highlights: • A hybrid electrolyte membrane for LiB based on nanostructured YSZ was sintered HP-FAST. • The nano-porosity was retained and the membrane activated with a standard LiPF₆-EC-DMC solution. • The liquid is nano-confined in the ceramic membrane. • Excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. • The nano-porous ceramic hybrid electrolytes may be conveniently used in LMB. -- Abstract: The use of lithium metal as the anode for Lithium Metal Batteries (LMB) requires having solid or quasi-solid electrolytes able to block dendrites formation during cell cycling. Here we reported on a hybrid electrolyte membrane based on nanostructured yttria-stabilized-zirconia, sintered by means of High Pressure-Field Assisted Sintering Technique (HP-FAST) in order to retain proper nano-porosity, and activated with a standard LiPF₆-EC-DMC solution. By a thorough physico-chemical and functional characterization, we demonstrated that the liquid is effectively nano-confined in the ceramic membrane, and the resulting quasi-solid electrolyte is non-flammable. A remarkable conductivity value of 0.91 mS cm⁻¹ was observed at room temperature, with activation energy of 0.2 eV, and cation transference number, t⁺ = 0.55, substantially higher than that of the pure liquid electrolyte. The hybrid electrolyte showed electrochemical stability up to 5.5 V vs. Li⁺/Li, and excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. A full cell Li/electrolyte/LiMn₂O₄ showed more than 90 mAh g⁻¹ at 2C for more than 120 cycles. These very promising results indicated that nano-porous ceramic hybrid electrolytes may be conveniently used in LMB.