Solid Through Rigid Electrolyte: Advanced Measurements

Na-based all-solid-state batteries (ASSBs) are promising alternatives to solve the intrinsic safety and raw materials availability issues related to current Li-ion technology. Moreover, they theoretically overcome the state-of-the-art performance of available cells, by enabling the use of metallic negative electrode. However, the metal penetration over cycling plagues the performance of ASSBs, leading to dangerous short circuits, which can be mitigated by opportune synthesis conditions of the solid electrolytes, as well as by opportune cell stack pressure. To get insights into Na-based systems, at present under explored, this project, STREAM (Sodium Through Rigid Electrolyte: Advanced Measurements), aims to study the relations between mechanical properties and electrochemical behaviour of a selected class of Na-based solid electrolytes, SEs (hydroborates and derivatives), prepared by cost-effective, solvent-free and upscalable mechanochemical syntheses. The metal propagation through the electrolyte will be studied by operando optical measurements on symmetrical Na|SE|Na cells, with an in-plane geometry, a cutting-edge investigation technique never applied to such class of materials, flanked by post mortem SEM and AFM characterizations. The opportune conditions of preparation and cell manufacturing (stack pressure, electrolyte thickness) preventing or limiting the dendrite formation will be therefore transferred to a complete cell prototype, equipped with high-voltage-operating positive electrodes. By correlating electrochemical signature with mechanism of cell failure driven by metal propagation inside the battery, this study will provide a reliable series of data that can open the gate for implementing AI-driven quality control and safety tests on commercial/prototypes ASSBs.