Shaping the Contact between Li Metal Anode and Solid‐State Electrolytes

Abstract

Scientific and technological interest in solid-state Li metal batteries (SSLMBs) arises from their excellent safety and promising high energy density. However, the practical application of SSLMBs is hindered by poor contact between the Li metal anode (LMA) and solid-state electrolytes (SSEs). To circumvent this limitation, a pattern-guided approach that shapes the LMA/SSE contact is disclosed to offer fast Li ion conduction in the interface. A thermallytreated copper foam is used as the lithophilic pattern to confine and guide Li for forming a tight contact with garnet-type SSE. The contact can be easily manipulated according to the shape of lithiophilic pattern, facilitating cell assembly. The resulting Li|patterned garnet|Li symmetric cell exhibits an interfacial resistance of 9.8 Ω cm 2 , which is dramatically lower than that of 998 Ω cm 2 for Li|pristine garnet|Li symmetric cell. Being used in Li-sulfur batteries, the patterned garnet effectively eliminates the polysulfide shuttle and enables stable cycling performance, showing a low capacity decay of 0.035% per cycle over 1000 cycles. The fundamental contact process of metallic anodes/SSEs is carefully investigated. This contact strategy provides a new design concept to improve the interface wettability via a lithiophilic pattern for a variety of SSEs that cannot wet with metallic anodes.

Recent Progress in Designing Stable Composite Lithium Anodes with Improved Wettability

“…[49] Placing a lithiophilic 3D host on an SSE surface can induce the infiltration of Li inside the scaffold and blur the Li/SSE interface (Figure 10b). [149] Without the treated copper foam (TCF) as the lithiophobic host, a large physical gap was observed between the Li metal and the garnet. By contrast, when using a TCF, molten Li was rapidly infused into the TCF and formed an intimate contact with the garnet (Figure 10b).…”

“…Reproduced with permission. [149] Copyright 2020, Wiley-VCH. c) Schematic illustration of the fabrication of a porous dense bilayer as an integral Li/EES configuration.…”

Interfaces in Garnet‐Based All‐Solid‐State Lithium Batteries

“…One group is materials that can form lithium alloys or Li-intercalated compounds. The typical examples are Au, [66] Ag, [67] Al, [68] Cu, [69] Ge, [70] Si, [71] and graphite [72][73][74] which can form Li/Au, Li/Ag, Li/Al, Li/Ge, Li/Si alloys, and lithiated graphite during the thermal annealing process. The alloying or lithiated process increased the wettability of Li and reduced the interfacial resistance to tens of ohms ( Table 1).…”

Single‐Ion Conducting Polymer Electrolytes for Solid‐State Lithium–Metal Batteries: Design, Performance, and Challenges

“…[ 11–15 ] Among various solid‐state electrolytes (SSEs), many efforts have been devoted to solid polymer electrolytes (SPEs), which possess numerous attractive properties, including high flexibility, processability, and shape versatility, as well as low density. [ 16–26 ] These unique properties may enable them to meet large‐scale electronic devices’ requirements. Comparing with well‐studied lithium salt doped polymers, typically poly(ethylene oxide) (PEO), pioneered by Wright and co‐workers in 1973, single‐ion conducting polymer electrolytes (SICPEs), ideally defined as polymer electrolytes with cationic transference number close to unity ( t Li + ≈ 1), are a more advantageous system.…”