Origin of Lithiophilicity of Lithium Garnets: Compositing or Cleaning?

Abstract

Garnet-type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZTO), a promising solid-state electrolyte, is reported to exhibit lithiophobicity. Herein, it is demonstrated that the origin of the lithiophobicity is closely related to the surface compositions of both the lithium and LLZTO. Surface impurities with high melting points such as Li 2 O, Li 2 CO 3 , LiOH, or LiF inhibit the wettability between lithium metal and LLZTO, and the widely adopted compositing strategy may improve the wettability by merely breaking the surface impurity layers. A simple but effective "polishingand-spreading" strategy is proposed to remove the surface impurities and obtain clean Li/LLZTO interfaces. Thus, a tight and continuous Li/LLZTO interface with an interfacial resistance of 17.5 Ω cm 2 is achieved, which leads to stable cycling of the symmetric Li cells and a critical current density up to 2.8 mA cm -2 . This work provides a new perspective to understand the lithiophilicity of garnet-type electrolytes and contributes to designing robust Li/garnet interfaces.

Directly Using Li2CO3 as a Lithiophobic Interlayer to Inhibit Li Dendrites for High-Performance Solid-State Batteries

“…To solve the Li|LLZTO interfacial problems caused by Li 2 CO 3 , one conventional strategy is to remove the Li 2 CO 3 on the LLZTO surface by physical or chemical methods, including mechanical polishing, , high-temperature treatment, and acid treatment. − However, these strategies usually introduce additional pollutants or induce the loss of Li to form some electrochemically conductive defects. , Another strategy is to convert the Li 2 CO 3 on the LLZTO surface into lithiophilic or lithium-conducting materials, such as LiCoO 2 , Li x SiO y , Li 3 PO 4 , and LiF. − This strategy usually requires a high equipment environment and adds production costs. Recently, Wang et al proposed to use Li 2 O and Li-Sr alloy as a lithiophobic interlayer and lithiophilic interlayer, respectively, to effectively inhibit the growth of Li dendrites .…”

“…To solve the Li|LLZTO interfacial problems caused by Li 2 CO 3 , one conventional strategy is to remove the Li 2 CO 3 on the LLZTO surface by physical or chemical methods, including mechanical polishing, 22,23 high-temperature treatment, 24 and acid treatment. 25−27 However, these strategies usually introduce additional pollutants or induce the loss of Li to form some electrochemically conductive defects.…”

Efficient Utilization of Macropores as Artificial Solid–Electrolyte Interphase Channels for High-Capacity Silicon/Graphite Anode Materials

“…Li–F and/or P-F/Li x PO y F z are generated with the decomposition of the electrolyte, and the low intense peaks in the polymer-impregnated electrode infer less electrolyte and/or salt decomposition upon cycling which in turn indicates the reduced SEI accumulation . The Li1s spectrum for pristine showed the presence of Li–F (55.6 eV), whereas only Li–O (53.7 eV) is found in the case of the 3PI electrode.…”

Recent advances in in situ and operando characterization techniques for Li7La3Zr2O12-based solid-state lithium batteries

“…Moreover, the laboratory-used Li foil surface was found to contain impurities such as Li 2 O, Li 2 CO 3 , LiOH or LiF as seen from the XPS depth profile. 146 It is critical to provide a clean Li surface for achieving close contact at the LLZO/Li anode interface. The clean Li surface can be realized by heating Li foil to a molten state and then scraping off the contaminated layer which floats on the surface.…”