High-Entropy Strategy Flattening Lithium Ion Migration Energy Landscape to Enhance the Conductivity of Garnet-Type Solid-State Electrolytes

Abstract

Garnet-type solid-state electrolytes with exceptional stability are believed to promote the commercialization of all solid-state lithium metal batteries. However, the extensive application of garnet-type solid-state electrolytes is greatly impeded on account of their low ionic conductivity. Herein, a high-entropy fast lithium-ion conductor Li7(La,Nd,Sr)3(Zr,Ta)2O12 (LLNSZTO) with high lattice distortion is designed. It is found that the enhanced ionic conductivity of the high entropy garnet-type solid-state electrolyte LLNSZTO is achieved by introducing disorder in the lattice, which creates fast ion penetration paths with flattened energy landscapes within the pristine ordered lattice. Thus, the prepared high-entropy garnet-type solid electrolyte LLNSZTO exhibits low activation energy for Li+ migration (0.34 eV) and elevated ionic conductivity (6.26 × 10−4 S cm−1). Full cells assembled with LLNSZTO electrolyte, lithium metal anode, and LiFePO4 (LFP) cathode exhibit excellent capacity retention of 86.81% after 200 cycles at room temperature. Moreover, the superior ionic conductivity of LLNSZTO enables all solid-state battery with high-loading LFP cathode (>12 mg cm−2), achieving stable cycling exceeding 120 cycles. The large area pouch cell (5.5 cm × 8 cm) exhibits stable long-term cycling performance, showing a capacity retention of 96.50% after 50 cycles.