Transport Phenomena of Lithium Metal and Solid Electrolyte in All-Solid-State Batteries

Abstract

Transportation accounts for nearly 25% of CO2 emissions worldwide and electrification of transportation are mandatory for disentangling this sector from fossil fuels. The prospect of the global electric vehicle (EV) market largely depends on the development of high energy density Li-ion batteries. Current battery technologies fall below the threshold (>900 Wh/L) for delivering a longer driving range per charge. Hence, next-generation battery technologies are looking for utilizing high energy density anodes (e.g., Lithium metal) and high voltage cathodes. Solid-state batteries (SSBs) are at the forefront of employing Li metal to boost energy density and enable safer alternatives for Li-ion batteries. However, the development of commercially viable solid-state batteries has been limited for their poor cyclability, short lifetime, and low coulombic efficiency. The underlying causes for the inadequate performance are generally attributed to the complex chemomechanics and transport limitations which lead to low ionic conductivity, morphological instability, and catastrophic dendrite-induced failure. A broad understanding of the ion conduction mechanism and interfacial dynamics is critical for failure prevention and rational designing of battery materials. In this work, we seek to employ direct and indirect characterization methods to understand the multi-material transport and change transfer phenomena that exist in solid-state batteries. At first, surface-driven ion transport properties of solid electrolytes are directly correlated to the percolation of interfacial regions with the aid of an advanced nanoscale imaging technique. Furthermore, the buried interfacial properties and electro-chemo-mechanics of Li-metal solid-state batteries are investigated to unravel the dynamic transformations of battery materials and their impact on cell stability. Several performance-limiting parameters are critically analyzed to highlight the challenges associated with high-performance solid-state batteries. Finally, we employed a mechanical stress monitoring strategy to probe the electrodeposition and shorting (failure) mechanism of solid-state batteries. The primary goal of this work is to expand our understanding of the transport properties of Li and solid electrolytes and the multi-faceted interfacial issues associated with battery performance. The outcome of this study is expected to provide a guideline for developing realistic solid-state battery architectures which can be scaled up for mass production.