Mixed ionic-electronic-conducting Interlayer Design for High-Performance Solid-State Lithium-Metal Batteries
Developing advanced energy storage systems may address the increasing concerns of energy shortage and environmental issues. Among many energy storage technologies, all-solid-state lithium metal batteries (ASSLBs) have been attracting considerable attention as safe and low-cost alternatives to Li-ion batteries. However, the performance of ASSLBs falls short of the requirements for commercial applications mainly due to the challenges at the electrode-solid electrolyte interface. The goal of this dissertation is to develop new interlayer and interfacial engineering methods for high-performance ASSLBs with favorable anode-electrolyte interfaces. In this dissertation, I demonstrate three effective strategies to address the interfacial challenges, namely through design and characterization of mixed ion-electron conductive interlayers. First, high-performance sheet-type all-solid-state lithium metal cells can be achieved using spray coated Ag-C interlayers due to their unique properties. The Ag-C interlayer improves the interfacial contact between Li anode and solid electrolyte, thereby homogenizing the Li+ flux and suppressing the lithium dendrite growth. Furthermore, controlled studies between pure carbon interlayer and Ag-C interlayer show that the presence of Ag metal improves Li diffusivity. Second, a homo-disperse Ag-C interlayer is developed to improve the stability at the anode-electrolyte interface. Agglomeration of Ag nanoparticles is eliminated by embedding Ag within a carbon matrix, and result in the formation of homo-disperse films in subsequent processes. A homo-disperse interlayer would provide a higher degree of percolation due to a long-range Li-Ag conducting cluster, resulting in rapid Li mass transport. The previous two studies primarily focused on the chemo-mechanical functionality and structural design of mixed ion-electron conductive interlayers utilizing Ag nanoparticles. The selection of different carbons, with varying surface areas, is crucial for stabilizing the anode-electrolyte interface. The presence of lithiated carbon on the surface plays a critical role in facilitating the mass transportation of Li ions. Furthermore, the carbon surface significantly influences the deposition patterns of lithium, with a larger surface area enabling faster Li atom kinetics and more favorable deposition at the bottom of the carbon interlayer. These findings underscore the importance of understanding and optimizing the properties of carbon-based interlayers for enhanced battery performance.