(Invited) Hard Chemistry: Solid State Electrolytes and Anode Protection for Solid State Lithium and Sodium Batteries

Abstract

The development of safe and high-performance all-solid-state batteries (ASSB) is contingent on creating fast ion conductors that combine high ionic conductivity with good ductility and chemical stability in a large voltage window, while - especially - mastering the interface of the solid electrolyte with the electrode materials. This presentation will examine ways to address these factors with new materials within the crystalline and glassy alkali thiophosphate families, while also shedding light on new design concepts for ion conductivity. The talk will cover an overview of the state-of-the art in the field, followed by recent findings in our laboratory. Significant increases in conductivity of thiophosphate-halide argyrodites, above that of the parent Li6PS5Cl phase, have been attained by both tuning composition and developing “clean” solution-engineering processing routes to these materials to create materials that exhibit ion conductivities above 1 mS/cm together with good chemical stability. An understanding of superionic conductivity in these and related crystalline and glassy alkali thiophosphates has been achieved using a combination of structural elucidation via single crystal X-ray/powder neutron diffraction, ion conductivity mechanisms via impedance studies and the maximum entropy method, 7Li MAS/PFG NMR, and ab initio molecular dynamics simulations. We correlate crystal structure with ionic conductivity to understand how cation disorder and a frustrated energy landscape affects the conductivity and activation energy. Last but not least, the talk will highlight our work on in-situ Li-ion conductive protective films for lithium metal batteries