Advancing High-Energy Solid-State Batteries with High-Entropy NASICON-type Solid Electrolytes

Herein, we have developed a High-Entropy (∼1.52 R, calculated at M-site) lithium-stuffed NASICON-type solid electrolyte [Li1.3Sn1.7/3Zr1.7/3Ti1.7/3Al0.1Sc0.1Y0.1(PO4)3] with a total (grain + grain-boundary) ionic conductivity of ∼1.42 × 10–4 S cm–1 (highest reported among NASICONs containing Zr–Sn–Ti) and a low activation energy of ∼0.33 eV with a relative density of Conventionally Sintered pellet ∼94%. Symmetric cells with a PVDF-HFP/LiTFSI buffer layer showed stable performance for 500 cycles at 0.2 mA cm–2 without short-circuiting. Full cells with LiFePO4 retained ∼99% capacity after 100 cycles at 1C, while those with NMC811 delivered ∼140 mAh g–1 at C/3.