UC San Diego

All solid-state batteries (ASSBs) show great promise toward becoming the dominant next-generation energy storage technology. Compared to conventional liquid electrolyte-based lithium ion batteries, ASSBs utilize nonflammable inorganic solid-state electrolytes (SSEs), which translate to improved safety and the ability to operate over a wider temperature range. Although the recent discoveries of highly conductive SSEs led to tremendous progress in ASSB’s development, they still face barriers that limit their practical application, such as poor interfacial stability, scalability challenges and limited performance at high current densities. Additionally, efforts to develop sustainable manufacturing of lithium ion batteries are still lacking, with no prevailing strategy developed yet to handle recyclability of ASSBs. Recognizing this, this dissertation seeks to evaluate SSEs beyond conventional factors and offer a perspective on various bulk/interface and chemical/electrochemical phenomena that are of interest to both the scientific community and the industry. Beginning from an introduction to the current state-of-the-art, rational solutions to overcome some major fundamental obstacles faced by the ASSBs will be discussed, strategies toward enabling scalability as well as potential designs for sustainable ASSB recycling models will be discussed. Specifically, lithium solid-state battery systems were studied using sulfide based SSEs. The electrochemical reactivity of the argyrodite Li6PS5Cl system was studied, to gain insight into its reaction mechanisms, products, and reversible redox behavior. In terms of scalability, binder-solvent-sulfide compatibility was evaluated, in order to enable scalable roll to roll processability of thin and flexible sulfide SSEs. To overcome performance limitations at the anode, carbon free alloys electrodes were enabled, achieving high critical current densities and low temperature operation of ASSB full cells, addressing a key bottleneck in ASSB development. Finally, a fully recyclable ASSB model was designed, incorporating direct recycling approaches that reduce energy and greenhouse gas emissions compared to conventional recycling technologies. Overall, this dissertation offers a deepened understanding of interfacial phenomena, and improved design strategies that translates into better material selection for high performance and sustainable ASSBs.