Scalable Hybrid Radioisotope-Thermoelectric and Li-Sulfur Systems for Centennial-Scale Autonomous Power: A Tiered Framework

Scalable Hybrid Radioisotope-Thermoelectric and Li-Sulfur Systems for Centennial-Scale Autonomous Power: A Tiered Framework This preprint presents a modular "Star within a Star" hybrid power architecture for extreme environments, including deep space, lunar night, and sub-oceanic applications. The system combines a constant ²⁴¹Am radioisotope thermoelectric generator (RTG) core using advanced topological insulator (Bi-Sb/Bi-Te + graphene) conversion with a high-energy-density Lithium-Sulfur (Li-S) battery reservoir. Key innovations include: - Tiered designs achieving 12–17% thermoelectric efficiency and system energy densities of 0.35–0.40 kWh/kg - Novel Hibernation Mode with 0.05 V bias and high-frequency regeneration pulsing (10–50 Hz) to mitigate polysulfide shuttle effects - Detailed thermal management using silica aerogel and liquid gallium cooling - Full end-to-end efficiency modeling and 100-year sensitivity analysis accounting for ZT degradation and Li-S fade The framework addresses limitations of traditional MMRTGs and offers a viable pathway for 100-year autonomous missions envisioned by ESA, NASA, and private aerospace companies. **Patent Status**: This invention is the subject of U.S. Provisional Patent Application No. 63/784,917, filed April 7, 2025. A non-provisional application is pending. **Communities**: Space Physics and Aeronomy (primary), EU Open Research Repository Keywords: Americium-241 RTG, topological insulator thermoelectrics, lithium-sulfur battery, hibernation mode, polysulfide mitigation, centennial power systems, YBCO superconducting bus, silica aerogel, ZT degradation