Orbital-Engineered Amorphous 4d Chloride Cathodes Enabling High-Voltage, Multi-Electron, Electrolyte-Free Solid-State Batteries

High Resolution Image Download MS PowerPoint Slide Achieving high energy density in all-solid-state batteries is often hindered by sluggish ion transport and cathode anion instability. To address this challenge, we introduce a rational design strategy that exploits the strong d−p orbital hybridization inherent in amorphous 4d transition-metal chlorides. As a model system, amorphous LiRuCl 4 exhibits an exceptionally high room-temperature Li + diffusion coefficient of 4.8 × 10 −9 cm 2 s −1 . When employed as an electrolyte-free cathode in an all-solid-state lithium-ion battery, it delivers an energy density of ∼472 Wh kg −1 (based on the total cathode mass) at 30 °C. Orbital-level stabilization of the M−Cl framework effectively suppresses Cl 2 evolution at potentials up to 4.4 V (vs. Li/Li + ), unlocking high-voltage multielectron chemistry. Consequently, this enhanced stability facilitates a highly reversible two-electron Ru 2+ / 3+ / 4+ redox process. Ultimately, engineering d−p hybridization in late transition-metal chlorides emerges as a promising design principle for developing next-generation high-energy-density solid-state battery cathodes.