Solid Electrolyte for Li-Ion Batteries: Synthesis, Characterization and Solid-State Cell Integration

Abstract

Combining nebulized spray pyrolysis (NSP) with field assisted sintering technology (FAST) provides a novel strategy for the preparation of ceramic electrolytes, e.g., garnet-type Li7-3xLa3Zr2AlxO12, with a homogeneous elemental distribution and high density. Utilizing FAST for ceramic preparation shows major impact on the structure and microstructure of the material. By varying the pressure during sintering, for instance, strong straining of the lattice can be induced, providing a high conductivity of 0.42 mScm-1. Therefore, this phenomenon might open a new field of research for garnet type electrolytes examining an enhancement of the electrochemical performance by introducing lattice strain. In this contribution, a detailed mechanism for the lattice distortion and resulting microstrain during FAST treatment of the garnet-type electrolyte is proposed. Furthermore, the charge transfer resistance of Li-ions at the interface, between the solid electrolyte and Li electrodes (characterized using AC impedance spectroscopy) is in the order of 37 Ωcm-2 and is among the best reported values to date. The ceramic electrolyte is fully functional and is integrated into both, an all-solid-state battery cell as well as a hybrid cell, the latter providing a practical approach to combine the advantages of the solid electrolyte with the good wetting behaviour of a liquid electrolyte to the slurry-based cathode material.