Ultrahigh Te-Content Low-Pressure All-Solid-State Li-Te Batteries

Tellurium (Te), with high volumetric capacity (2621 mAh cm^-3) and decent electronic conductivity (2000 mS cm^-1), has emerged as a promising cathode material for future lithium metal batteries. However, all-solid-state batteries (ASSBs) with Li-Te chemistry remain largely unexplored. Here, we construct a nanostructured Te₉₁@LPSC-350 composite in which ∼10 nm Te domains are uniformly embedded within an amorphous Li_5.5PS_4.5Cl_1.5 (LPSC) matrix, featuring an ultrahigh Te content of 91 wt % and intimate solid-solid contact. This nanocomposite exhibits high electronic conductivity (121 mS cm^-1) and appreciable ionic conductivity (0.1 mS cm^-1, after lithiation), enabling ultrafast and highly reversible Te redox reactions in the solid-state. Resultantly, ASSBs with the Te₉₁@LPSC-350 nanocomposite cathode deliver their theoretical capacity of 420 mAh g^-1 at 0.25 mA cm^-2, maintain ultralong cycling stability over 13,000 cycles at 12.5 mA cm^-2, and achieve a high areal capacity of 21 mAh cm^-2. Furthermore, all-solid-state Li-Te pouch cells with an energy density of 1100 Wh L^-1 (based on Li and Te₉₁@LPSC-350) retain 81% of their initial capacity after 200 cycles under 2.5 MPa. Notably, Te can be directly recovered by exploiting its 100% selectivity in a vaporization-condensation process. These results demonstrate that all-solid-state Li-Te batteries are a safe, energy-dense, and sustainable energy storage technology.