Combining Solid Solution Strengthening and Second Phase Strengthening for Thinning Li Metal Foils

Abstract

Thin lithium (Li) metal foils have been proved to be indispensable yet elusive for practical high-energy-density lithium batteries. Currently, the realization of such thin foils (<50 μm) is impeded by the inferior mechanical processability of metallic Li. In this work, we demonstrate that the combination of solid solution strengthening and second phase strengthening, achieved by the addition of silver fluoride (AgF) to Li metal, can substantially enhance both the strength and ductility of metallic Li. Benefiting from the improved machinability, we succeed in fabricating an ultrathin (down to 5 μm), freestanding, and mechanically robust Li-AgF composite foil. More interestingly, the in situ-formed Li x Ag-LiF skeleton in the composite facilitates Li diffusion kinetics and uniform Li deposition, where the thin Li-AgF electrode displays a prolonged cycle life over 500 h at 1 mA cm–2 and 1 mAh cm–2 in a carbonate electrolyte. Coupled with a commercial LiCoO2 cathode (3.4 mAh cm–2), the LiCoO2||Li-AgF cell delivers a notable capacity retention of ∼90% over 100 cycles at 0.5 C with a low negative/positive ratio of 2.5.

Superdense Lithium Deposition via Mixed Ionic/Electronic Conductive Interfaces Implanted In Vivo/Vitro for Stable Lithium Metal Batteries

“…However, fabricating and stabilizing Li thin foils <50 µm are still daunting due to the poor processability of Li and its inherent instability in LEs. [ 25 ] Although P–Li can also be rolled to a thickness of ≈77 µm (Figure 6c), Li foil is tightly sticking onto the roller, and obvious cracks appear, indicating a mechanical failure. Here, it is found that a doping of 5 wt% AlN substantially improves the machinability of Li, allowing a self‐supporting foil of only 35 µm (Figure 6d).…”

Advancing anode-less lithium metal batteries: ZnF2 modification and in situ structural regulation for enhanced performance

“…By incorporating silver into lithium metal to form LiAg alloys, the machinability of lithium metal can be greatly improved, enabling the fabrication of ultrathin lithium foils. 34,35 By utilizing the lithiophilicity of LiZn alloys, the molten LiZn alloys can be easily spread on a copper foil and form a controllable thickness negative electrode. 18 Additionally, LiSn alloys enable the large-scale printing of flexible ultrathin (15 μm) lithium alloy negative electrodes.…”

A Multiscale, Dynamic Elucidation of Li Solubility in the Alloy and Metallic Plating Process

“…The lithiation induced alloying process involves the continuous formation of Li‐containing intermediates with gradually enhanced Li solubility, leading to higher gravimetric capacities as compared to graphite anodes that are based on intercalation chemistry. [ 1–9 ] Li‐M alloys (M = Zn, Al, Ag, Sn, etc.) have also been investigated as preferential nucleation sites in metallic batteries, mitigating the nucleation overpotentials.…”