14a Reliable fabrication of all-solid-state lithium batteries with high cell-level specific energy

All-solid-state lithium metal batteries are projected to be one of the most energy-dense rechargeable batteries, hence a promising candidate to support commercialization of electric vehicles. A key technical barrier for all-solid-state lithium metal batteries to hit the projected specific energy target is to fabricate solid-state electrolyte membranes that are 10% thinner than those used in typical laboratory setups. Research groups and prospective manufacturers are each developing their own method of fabricating thin electrolyte membranes but there is yet one widely reproduced, and a thin electrolyte membrane that supports the operation of lithium metal electrode at practical current density is still critically needed. An underlying challenge facing these particle-derived thin membranes is how to eliminate bulk defects, from which lithium dendrites are found to originate especially under fast charging rates. The proposed Phase I project will develop a method to reliably fabricate high-quality solid-state electrolyte thin membranes. To achieve this goal, fundamental understanding of selection criteria of membrane precursors, optimization of processing procedure, and establishing the correlation between membrane properties and cell performance will be the focus of this project. In Phase I, we will perform a rational screening of materials to identify a suitable combination of materials with the desirable properties to minimize defect formation. We will then optimize the processing conditions to reproducibly fabricate thin membranes with high uniformity and low defects. Finally, we will incorporate the fabricated electrolyte membranes into high-energy lithium cells to demonstrate fast-charging all-solid-state lithium pouch cells. Upon successful completion of Phase I, we will scale up the fabrication process for large-area thin membranes and demonstrate large-format pouch cells in Phase II, which will be eventually co-developed with manufacturing partners into batteries suitable for use in electric vehicles.