Enhanced Ionic Conductivity and Stability in Li ₁₀ SnP ₂ S ₁₂ Solid Electrolytes via Tellurium Anionic Doping

Sulfide solid electrolytes enable high-performance all-solid-state batteries, where Li 10 SnP 2 S 12 (LSPS) offers LGPS-comparable conductivity with superior resource sustainability, yet faces challenges in balancing ionic transport and stability. This study synthesized Te-doped Li 10 SnP 2 S 12-x Te x (LSPST, 0 ≤ x ≤ 0.25) electrolytes via high-energy ball milling combined with gradient annealing. Structural analyses confirm uniform Te substitution at S sites. At the optimal doping level ( x = 0.1), the modified electrolyte exhibits significantly improved performance, demonstrating a 45.2% enhancement in ionic conductivity (4.3 × 10 –3 S cm –1 ) compared to pristine LSPS, along with a lower activation energy (0.259 eV) and superior electrochemical stability. Theoretical calculations reveal that Te doping facilitates Li + transport through elongated Li–Te bonds, weakening Li + -framework interactions and anisotropic z -axis diffusion (validated by molecular dynamics). Simultaneously suppresses electronic conductivity (8.33 × 10 –9 S cm –1 ) to inhibit dendrites, it enables superior full-cell performance in Li–In/LSPST/Li 6 PS 5 Cl/NCM811) cells, delivering 136.1 mAh g –1 initial capacity with 67.9% capacity retention after 50 cycles, outperforming undoped counterparts by 86%. This work establishes an anionic doping strategy to concurrently enhance ionic transport and stability in cost-effective sulfide electrolytes.