Solid electrolyte is the key component in all-solid-state-batteries that is currently limiting the commercialization of this technology. An ideal solid electrolyte should have high room temperature ionic conductivity, low electronic conductivity, good compatibility with both cathode and anode, good mechanical properties, high air and moisture stability and low manufacture cost. Among these requirements, the improvement of ionic conductivity is prioritized as the conductivity of most existing solid electrolyte is still much lower than that of conventional liquid electrolyte.

The improvement of ionic conductivity and design and development of solid electrolyte materials are closely related to our understanding on the ionic diffusion mechanism in solids and the structure-property relationship. We believe that rational design of high-performance solid electrolyte should start from careful characterization and good understanding of the crystal structure. Here we report the crystal structure characterization on sulfides and halide solid electrolytes and the design and development of novel solid electrolytes based on our findings in structural characterizations. Ex situ high resolution synchrotron X-ray and neutron diffraction and pair distribution function analysis are used to understand the crystal structures in great details. In situ X-ray diffraction for different synthesis methods is coupled with variable temperature electrochemical impedance spectroscopy to understand the structure-property relationship in the solid electrolytes. The design, synthesis and electrochemical evaluation of several solid electrolytes will be presented and discussed.