Enhanced Ionic Conductivity and Stability in Li₁₀SnP₂S₁₂ Solid Electrolytes via Tellurium Anionic Doping

Sulfide solid electrolytes enable high-performance all-solid-state batteries, where Li₁₀SnP₂S₁₂ (LSPS) offers LGPS-comparable conductivity with superior resource sustainability, yet faces challenges in balancing ionic transport and stability. This study synthesized Te-doped Li₁₀SnP₂S_12-xTe_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/Li₆PS₅Cl/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.