Abstract: Conceptual design of molecular rotors based framework materials is of great importance among energy storage and conversion technology applications. Research endeavours in the pursuit of next generation “super-protonic solid acids proton conductors” for Fuel Cell applications and as “solid state electrolyte (SSE)” for all solid state batteries has seen a huge research thrust in the recent decade. The basic concept rely solel on understanding the dynamics of ROTOR molecules ideally incorporated within the framework assembly that exhibits rapid reorientation of XO4 anion groups as the mechanism of proton transport.

In the first round of the talk, I will be talking about the conceptual designing of new ROTOR molecules and their role in achieving high proton conductivity as a substituent to NAFION membrane for PEM(proton exchange membrane) Fuel Cells. The preliminary focus would be to spotify new kind of hybrid functional architecture materials for their application in fuel-cell-powered vehicles. Focus will be to highlight new phosphate and silicate analogue to known sulfate and selenate solid acids with high conductivity and subsequently discuss methodologies to incorporate these functional guest rotor molecules into potential framework architeture, that will facilitate proton conduction through well defined crystalline pores at wide-ranging temperature window.

In second phae of talk, I will focus on the screening of potent rotor molecules as superion conducting solid state electrolyte (SSE) materials that offers high ionic conductivity, good ductility and processability, as well as good compatibility with the electrode rendering their ideal use in the research and application of all solid state batteries(ASSBs). The typical structural feature of these SSE decorated with “rotatable polyanion” is that the high temperature-induced drastic increase in the atomic displacement parameters (ADPs) of cental atoms with huge thermal ellipsoids, in such a way that the atoms ‘jump’ in a quantum-like manner from a given well-defined orientation into a dynamically disordered framework with subsequent disordered phase transition triggered by polyanion rotation leading to a sharp increase of cationic conductivity. Therefore, it is of great significance to get in depth structural insight into the rotational dynamics of polyanions in order to further optimize the properties (ion conduction and interface compatibility) of novel solid electrolyte. I will briefly discuss how the operando/in-situ synchrotron powder X-ray and neutron diffraction can be concomitantly used to study the rotational dynamics of polyanions in novel solid state electrolyte materials. The role of precise doping of selected elements at corresponding lattice sites will also be highlighted besides quantifying and discussing strategies to circumvent the emerging amorphous phases responsible for creating large charge transfer resistance at the Solid Electrolyte Interface (SEI).

Keywords: Solid electrolyte materials; Rotating dynamics of polyanions; Synchrotron X-Ray & neutron powder diffraction