Rationally Designed PEGDA-LLZTO Composite Electrolyte for Solid-State Lithium Batteries

A novel composite electrolyte is rationally designed with a polyethylene glycol diacrylate (PEGDA) polymer and a garnet-type fast lithium-ion conductor (Li_6.4La₃Zr_1.4Ta_0.6O₁₂, LLZTO) for solid-state lithium batteries. The LLZTO ceramic phase is incorporated into the PEGDA polymeric matrix as nanoparticles. The ionic conductivity of the composite is further optimized with a succinonitrile plasticizer. The solid composite membranes are synthesized via a tape casting process followed by a UV curing procedure. The resulting solid-state composite electrolyte delivers a room-temperature Li⁺-ion conductivity of 3.1 × 10^-4 S cm^-1 and can sustain an electrochemical polarization potential up to 4.6-4.7 V (vs Li⁺/Li). The compositing approach harnesses the advantages of both polymeric PEGDA and ceramic LLZTO. In addition to enhancing the ionic conductivity, the LLZTO ceramic filler can suppress Li dendrites. The polymeric phase of PEGDA facilitates good interfacial contact between the solid electrolyte and the electrodes. The solid-state cells fabricated with the composite solid electrolyte, lithium-metal anode, and LiNi_0.8Mn_0.1Co_0.1O₂ (NMC 811) cathode show long cyclability.