Oxide ceramic electrolytes for all-solid-state lithium batteries – cost-cutting cell design and environmental impact

Abstract

All-solid-state batteries are a hot research topic due to the prospect of high energy density and higher intrinsic safety, compared to conventional lithium-ion batteries. Of the wide variety of solid-state electrolytes currently researched, oxide ceramic lithium-ion conductors are considered the most difficult to implement in industrial cells. Although their high lithium-ion conductivity combined with a high chemical and thermal stability make them a very attractive class of materials, cost-cutting synthesis and scalable processing into full batteries remain to be demonstrated. Additionally, they are Fluorine-free and can be processed in air but require one or more high temperature treatment steps during processing counteracting their ecological benefits. Thus, a viable cell design and corresponding assessment of its ecological impact is still missing. To close this gap, we define a target cell combining the advantages of the two most promising oxidic electrolytes, lithium lanthanum zirconium oxide (LLZO) and lithium aluminium titanium phosphate (LATP). Even though it has not been demonstrated so far, the individual components are feasible to produce with state-of-the-art industrial manufacturing processes. This model cell then allows us to assess the environmental impact of the ceramic electrolyte synthesis and cell component manufacturing not just on an abstract level (per kg of material) but also with respect to their contributions to the final cell. The in-depth life cycle assessment (LCA) analysis revealed surprising similarities between oxide-based all-solid-state batteries and conventional Li-ion batteries. The overall LCA inventory on the material level is still dominated by the cathode active material, while the fabrication through ceramic manufacturing processes is a major contributor to the energy uptake. A clear path that identifies relevant research and development directions in terms of economic benefits and environmental sustainability could thus be developed to promote the competitiveness of oxide based all-solid-state batteries in the market.