cells with the composite solid electrolyte were prepared in a glove box
of argon atmosphere.
The synthesized LTAPO powder X-ray diffraction data were mea- sured at 298 K on an X-ray
diffractometer (XRD, Rigaku Mini Flex II,
Japan) using Cu Ka radiation (λ = 1.5046 Å). It was operated at 30 kV
and 15 mA in step-scan mode with a step size 0.02° and a scan speed of 2°/min. The morphologies of
the synthesized powders and LTAPO– PTFE composite electrolyte were observed by scanning electron
microscopy (SEM, FEI, VERIOS VR87, USA). Electrochemical impedance spectroscopy (EIS) for LTAPO
powders and LTAPO–PTFE composite electrolytes with/without 1 M LiPF6 in EC/DMC was measured under
pressure at 2 ton inside an Al2O3 mold and in an exclusive jig, respec- tively. The impedance
measurements were performed with a potentiometer (WonA tech. co., ZIVE SP2, Korea) in the
frequency range of 1 MHz to 0.1 Hz with applied AC voltage amplitude of 100 mV [24]. The ionic
conductivities of solid the electrolyte were calculated with
their geometric factor by blow equation.