Origin of Lithiophilicity of Lithium Garnets: Compositing or Cleaning?

摘要

Garnet-type Li_(6.5)La_3Zr_(1.5)Ta_(0.5)O_(12) (LLZTO), a promising solid-state electrolyte,is reported to exhibit lithiophobicity. Herein, it is demonstrated that the originof the lithiophobicity is closely related to the surface compositions of both thelithium and LLZTO. Surface impurities with high melting points such as Li_2O,Li_2CO_3, LiOH, or LiF inhibit the wettability between lithium metal and LLZTO,and the widely adopted compositing strategy may improve the wettability bymerely breaking the surface impurity layers. A simple but effective “polishingand-spreading” strategy is proposed to remove the surface impurities and obtainclean Li/LLZTO interfaces. Thus, a tight and continuous Li/LLZTO interface withan interfacial resistance of 17.5 Ω cm~2 is achieved, which leads to stable cyclingof the symmetric Li cells and a critical current density up to 2.8 mA cm~(–2). Thiswork provides a new perspective to understand the lithiophilicity of garnet-typeelectrolytes and contributes to designing robust Li/garnet interfaces.