PNNL

Abstract

Lithium-sulfur (Li-S) batteries involve complex solid-liquid-solid phase transformations during both discharging and charging processes, where cathode materials, formulation, and structure play a crucial role. Here, a design of experiments (DoE) methodology is developed to systematically explore the interactions and trade-offs among cathode factors and process variables, and to obtain generalizable effects estimates for the multivariate system. Compared to the conventional one-factor-at-a-time (OFAT) approach, this work demonstrates advantages in both efficiency and accuracy by allowing the data to guide future research and decisions. An optimized cathode formulation and processing is predicted and validated experimentally, achieving over 1000 mAh g-1 in discharge capacity for 30 cycles and greater than 80% capacity retention for > 50 cycles under lean electrolyte conditions with high S-loading cathodes (>4 mg cm-2). This work provides a comprehensive and rigorous framework for optimizing complex systems similar to the sulfur cathode with DoE and offers insights into the underlying mechanisms of sulfur reactions.