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 Li5.5PS4.5Cl1.5 (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.