Polysulfide Shuttling Reduction Project

From Space Force Technical Need 714, Space Battery Cell Specific Energy, ōģenergy storage cells have the most substantive LEO satellite subsystem mass in 2023 and typically the highest target signature impact on a spacecraft (systems) level.öĀ The Space Force problem is that: it needs higher specific energy batteries, to reduce the size of the satellite, to enable target signature reduction for the warfighter. U.S. Space Force's (USSF) had targeted a short-term 18650 rechargeable battery target of 450 W-h/kg. A higher energy rechargeable power source would have impacts across all areas of the USSF mission to enable spacecraft resilience and survivability. Most practical issues with Lithium-Sulfur chemistry can be attributed to ōpolysulfide shuttling, the dissolution of Lithium Polysulfide in liquid electrolyte which results in parasitic reactions and its relatively low volumetric energy density, especially when in a small form factor battery cell such as an 18650. These reactions cause low Sulfur utilization and capacity fade, resulting in poor cycling efficiency. Recent efforts have been focused on either (1) suppressing diffusion of the dissolved polysulfides out of the cathode, or (2) protecting the lithium anode from reacting with the dissolved polysulfides. Li-S modelling is necessary to understand the technology development way-forward. This topic proposes the investigation of these or other methods to mitigate the inhibiting effects of polysulfide dissolution and improve its volumetric energy density. Findings will be incorporated into materials and 18650 cell design that can improve cycle life performance while maintaining a high specific energy intrinsic to the chemistry.Ā The Space Force Energy Storage Roadmap details the requirements for Space Force state-of-practice mission energy requirements.Ā These requirements are benchmarked by orbit, mission duration, and current specific energy, cycle length, and depth of discharge characteristics of Lithium-ion (Li-ion) batteries currently used in all missions.Ā Ā