Si–Ge alloys as promising anodes for sulfide-based solid-state batteries: Role of the powder morphology on performance

As the demand for safe, high-energy energy storage devices grows with the energy transition, all-solid-state batteries (ASSBs) have become the central focus of research. This pioneering study explores Si 0.5 Ge 0.5 alloys as negative electrode for sulfur-based ASSBs, and how the morphology and electrode formulation protocols influence their electrochemical performance. Two distinct morphologies of Si 0.5 Ge 0.5 alloys were synthesized via ball-milling (BM) and laser pyrolysis (LP). Composite electrodes were prepared using two different protocols: densification and casting. The distribution of the composite electrode components was analyzed using SEM/EDX. Electrochemical performance was evaluated in half-cells using argyrodite as the solid electrolyte, through galvanostatic cycling, derivative analysis, and electrochemical impedance spectroscopy (EIS). Particularly, for the LP-cast composite electrode, a high specific capacity of 1580 mAh g −1 am was achieved at C/5, with 86 % capacity retention after 45 cycles. Additionally, the electrochemical behavior and performance of both BM and LP Si 0.5 Ge 0.5 alloys were compared to those in a liquid electrolyte system with a classical electrode formulation, revealing similar (de)lithiation mechanisms to those in solid-state configuration. • Si 0.5 Ge 0.5 alloy allows enhanced lithiation depth compared to pristine Si. • Nano-sized Si 1-x G ex alloys achieved a specific capacity of 1580 mAh g −1 at C/5. • Nano-sized Si 1-x G ex alloys demonstrated 86 % of capacity retention after 45 cycles. • (De)lithiation mechanisms in liquid and solid electrolytes are comparable.