LiF-Rich Interfacial Protective Layer Enables Air-Stable Lithium Metal Anodes for Dendrite-Free Lithium Metal Batteries

Abstract

Lithium (Li) metal is considered as a promising anode candidate for high-energy-density batteries. However, the high reactivity of Li metal leads to poor air stability, limiting its practical application. Additionally, the interfacial instability, such as dendrite growth and an unstable solid electrolyte interphase layer, further complicates its utilization. Herein, a dense lithium fluoride (LiF)-rich interfacial protective layer is constructed on the Li surface through a simple reaction between Li and fluoroethylene carbonate (denoted as LiF@Li). The LiF-rich interfacial protective layer consists of both organic (ROCO2Li and C–F-containing species, which only exist on the outer layer) and inorganic (LiF and Li2CO3, distribute throughout the layer) components with a thickness of ∼120 nm. Specifically, chemically stable LiF and Li2CO3 play an important role in blocking air and hence improve the air durability of LiF@Li anodes. Notably, LiF with high Li+ diffusivity facilitates uniform Li+ deposition, while organic components with high flexibility relieve volume change upon cycling, thereby enhancing the dendrite inhibition capacity of LiF@Li. Consequently, LiF@Li exhibits remarkable stability and excellent electrochemical performance in both symmetric cells and LiFePO4 full cells. Moreover, LiF@Li maintains its initial color and morphology even after air exposure for 30 min, and the air-exposed LiF@Li anode still retains its superior electrochemical performance, further establishing its outstanding air-defendable capability. This work proposes a facile approach in constructing air-stable and dendrite-free Li metal anodes toward reliable Li metal batteries.

Stabilizing Lithium-Metal Host Anodes by Covalently Binding MgF2 Nanodots to Honeycomb Carbon Nanofibers

“…This can be attributed to the abundant voids of the nanofibers with a large number of channels for the charge transport and in situ generation of a LiF-rich SEI layer, characterized by exceptional ionic conductivity and mechanical robustness. Such a LiF-rich SEI layer can enhance interfacial stability and promote rapid Li plating/stripping kinetics . Moreover, the Tafel slopes (Figure j) for the MgF 2 /HCNF-Li symmetric cells (0.56 mA cm –2 ) are greater than those of bare Li (0.1 mA cm –2 ), further emphasizing the swift Li-ion transfer kinetics within the MgF 2 /HCNF-Li electrode.…”

Studies on Composite Solid Electrolytes with a Dual Selective Confinement Interface Structure of Anions for High-Performance Lithium Metal Batteries

“…Analysis of the XPS results shows that the SEI surface consists mainly of an organic outer layer and an inorganic inner layer . In Figure a, the peak at 685.1 eV is corresponded to the Li–F bonding and is stronger in the HMOF-DNSE than in the others, which is considered to be the buffer layer to facilitate fast and uniform Li + transportation in SEI and promote uniform lithium deposition . Similar to Li–F, Li–N is also regarded as a beneficial component of SEI, which is able to suppress the growth of Li dendrites .…”

Recent Progress on Nanomodification Applied in Anodes of Rechargeable Li Metal Batteries

“…Surface coating and the creation of an artificial SEI as a protective layer have both been intensively researched as solutions to this problem. Various coating materials such as LiF, , Al 2 O 3 , poly­(ethylene oxide), and so on have been investigated to improve the cycling performance in LMBs. An artificial SEI with flexibility, stability, and high mechanical strength is demonstrated for the efficient and safe operation of a lithium metal anode …”