Scaling Synthesis of Sulfur Cathode Materials: an Analysis of Sulfur Distribution to Achieve High Performing Lithium-Sulfur Batteries

Abstract

As a promising candidate for next-generation high performance lithium batteries, lithium-sulfur (Li-S) technology has been widely explored in academia. With a wide variety of cathode materials validated, the next step towards practical development is to be able to scale up their production while maintaining consistent quality. This thesis, in collaboration with the Pacific Northwest National Laboratory (PNNL), focuses on the reproduction of a nitrogen-doped Ketjen Black/sulfur (NKB/S) composite material developed at PNNL with the goal of producing batches at a consistent quality before scaling up. During the material and electrochemical validation of the material, it was found that, while very similar to the standard NKB/S produced at PNNL, a major quality difference was found in the sulfur content distribution across particle sizes. Sulfur distribution in the usable 25-90µm NKB/S was found to consistently have 2-4% extra wt.% sulfur than the target, while the material <25µm were missing almost an equivalent amount of sulfur. Theories behind this phenomenon and further validations are discussed and proposed.