Assembling an All-Solid-State Ceramic Battery: Assessment of Chemical and Thermal Compatibility of Solid Ceramic Electrolytes and Active Material Using High Temperature X-Ray Diffraction

Abstract

Lithium ion batteries (LIBs) are the most known and used batteries for portable energy storage because of their high energy densities, long cycle life and relatively low price. However, they still fall short for the development of long range electric vehicles and stationary applications due to organic liquid electrolytes that are currently electrochemically limited and present safety issues (fire or explosion in case of short-cut or overcharging). Solid oxide electrolytes appear to be one of the solutions because of their non-flammability and wide potential window. Inorganic oxide electrolytes have reasonable ionic conductivities (10-5-10-3 S/cm at ambient temperature), high mechanical strength, and high chemical stability.Assembling an all ceramic solid-state battery with inorganic oxide electrolyte is challenging as it requires a deep knowledge of the thermal, chemical and electrochemical behavior of each component of the cell. The battery must be a continuous monolithic block with a thin dense electrolyte separator, in order to minimize the polarization. In addition, optimized interfaces between active material and electrolytes must be ensured in the composite electrodes. This is often achieved with oxide-based materials by using high temperature processing.Thermal expansion occurring during this step can lead to cracks, which will affect the performance and cyclability of the device. The primary driving force of a crack during the fabrication of hybrid ceramic is the stress due to mismatch in the coefficient of thermal expansion (TEC) of the various layers/materials. Moreover, it must be certain that no reaction occurs between active material and electrolytes in the sintering temperature range. These are then two key parameters to address for the development of all ceramic solid-state batteries.In this work, in situ-XRD has been used to determine the TEC and the thermal stability of various well-known oxide active materials and solid electrolytes. The aim of this presentation is to discuss about the best selection of compatible oxide-based materials to avoid unwanted cracks or reaction during the sintering processing of ceramic solid-state batteries.