(Invited) Factors Guiding the Stability Sulfide and Oxide Solid-State Electrolyte Interphases with Lithium Metal

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Site-specific microstructural analysis combined with interphase design is employed to understand the origin of solid-state electrolyte failure, and to promote extended electrochemical stability. For example, stable anode-free all-solid-state battery (AF-ASSB) with an argyrodite is achieved by tuning wetting of lithium metal on “empty” copper current-collector by coating it with a thin composite film of thermodynamically stable Li2Te and Cu microparticles. Cryo-FIB sectioning demonstrates a dense and uniform electrodeposit, with minimal voiding or dendrites at the collector-SSE interface. Unmodified Cu current-collector promotes inhomogeneous Li electrodeposition/dissolution, leading to a thick non-uniform solid electrolyte interphase (SEI) interspersed with voids. As another example, thin intermetallic Li2Te–LiTe3 bilayer derived from 2D tellurene stabilizes the Li-argyrodite SEI, allowing state-of-the-art electrochemical performance with conventional foils. The Li2Te–LiTe3 bilayer impedes SSE decomposition and suppresses voiding. Unmodified Li–LPSCl undergoes reduction decomposition that extends deep into the SSE, causing reactivity-induced voids in both metal and SEI. For the first time, short-circuiting Li metal dendrite is directly identified, employing 1.5 mm diameter "mini" symmetrical cell and cryogenic focused ion beam (cryo-FIB) electron microscopy. The branching sheet-like dendrite traverses intergranularly, filling the interparticle voids and forming an SEI around it. A separate study on dendrites in garnet LLZTO demonstrates that the compact's grain size distribution and internal porosity critically affect electrical short-circuiting, indicating the importance of local electronic properties. Lithium dendrites propagate intergranularly through regions where LLZTO grains are statistically smaller than the bulk average. Metal also accumulates in the otherwise empty pores of sintered compact present along the dendrite path. Related Work: Mechanical Milling - induced Microstructure Changes in Argyrodite LPSCl Solid-State Electrolyte Critically Affect Electrochemical Stability, Advanced Energy Materials. 2024, in-press. Dendrite Growth—Microstructure—Stress—Interrelations in Garnet Solid-State Electrolyte. Advanced Energy Materials. 2024, 2303062. https://doi.org/10.1002/aenm.202303062Stable Anode‐Free All‐Solid‐State Lithium Battery through Tuned Metal Wetting on the Copper Current Collector. Advanced Materials . 2022 Nov 29:2206762.Tuned Reactivity at the Lithium Metal–Argyrodite Solid State Electrolyte Interphase. Advanced Energy Materials . 2023 Dec;13(46):2301338.