Institute of Fundamental Technological Research

We report the influence of the partial substitution of Ge with Ti on the properties of NASICON Li1.5Al0.5Ge1.5(PO4)3 (LAGP) nanofibers prepared by electrospinning. Replacing a small amount of Ge (up to 20%) with Ti is advantageous for enhancing both the purity and morphology of LAGP fibers, as observed by X-ray diffraction, electron microscopy and nuclear magnetic resonance spectroscopy. When Ti-substituted LAGP (LAGTP) fibers are used as filler to develop composite polymer electrolytes, the ionic conductivity at 20 °C improves by a factor of 1.5 compared to the plain polymer electrolyte. Additionally, above 40 °C the LAGTP fiber-based composite electrolytes were more conductive than the equivalent LAGP fiber-based one. We believe that these findings can make a substantial contribution to optimizing current methods and developing novel synthesis approaches for NASICON based electrolytes.

We report the synthesis of ceramic Li1.5Al0.5Ge1.5(PO4)3 (LAGP) nanofibers by combining sol–gel and electrospinning techniques. A homogeneous and stable precursor solution based on chlorides was achieved by controlling Ge hydrolysis. Subsequent electrospinning and heat treatment resulted in highly porous nanostructured NASICON pellets. After a full chemical-physical characterization, various amounts of LAGP nanofibers were used as a filler to develop polyethylene oxide (PEO)-based composite electrolytes. The addition of 10% LAGP nanofibers has allowed doubling the ionic conductivity of the plain polymer electrolyte, by providing longer ion-conductive paths and reducing PEO crystallinity. These findings are promising towards developing solution-based synthesis approaches featuring Ge precursors. In addition, the achieved LAGP nanofibers proved to be a promising nanofiller candidate to develop composite electrolytes for next-generation solid-state batteries.