Two-Dimensional Phosphorene-Derived Protective Layers on a Lithium Metal Anode for Lithium-Oxygen Batteries

Abstract

Lithium-oxygen (Li-O) batteries are desirable for electric vehicles because of their high energy density. Li dendrite growth and severe electrolyte decomposition on Li metal are, however, challenging issues for the practical application of these batteries. In this connection, an electrochemically active two-dimensional phosphorene-derived lithium phosphide is introduced as a Li metal protective layer, where the nanosized protective layer on Li metal suppresses electrolyte decomposition and Li dendrite growth. This suppression is attributed to thermodynamic properties of the electrochemically active lithium phosphide protective layer. The electrolyte decomposition is suppressed on the protective layer because the redox potential of lithium phosphide layer is higher than that of electrolyte decomposition. Li plating is thermodynamically unfavorable on lithium phosphide layers, which hinders Li dendrite growth during cycling. As a result, the nanosized lithium phosphide protective layer improves the cycle performance of Li symmetric cells and Li-O batteries with various electrolytes including lithium bis(trifluoromethanesulfonyl)imide in N,N-dimethylacetamide. A variety of ex situ analyses and theoretical calculations support these behaviors of the phosphorene-derived lithium phosphide protective layer.

Safe Lithium‐Metal Anodes for Li−O2 Batteries: From Fundamental Chemistry to Advanced Characterization and Effective Protection

“…Lee et al. conducted ex‐situ NMR on cycled Li‐metal anode in an DMA electrolyte under two different protective conditions and provided valuable information about the decomposition of the electrolyte, Figure d . Obviously, NMR/MRI are outstanding techniques which can provide both morphology and chemical composition information.…”

Lithiophilic Silver Coating on Lithium Metal Surface for Inhibiting Lithium Dendrites

“…The high ionic conductivity of Li 2 S relieved non-uniform Li ions flux and suppressed Li dendrites, but it is almost an insulator. Kim et al proposed a method that phosphorene is added dropwise on the Li foil surface (Kim et al, 2018). The phosphorene layer located above the Li surface spontaneously reacts with Li to form Li 3 P. The phosphorene-coated Li metal electrode displayed a constant capacity of 1,000 mAh g −1 with no capacity reduction even after 50 cycles for the Li-O 2 battery.…”

An Extremely Simple Method for Protecting Lithium Anodes in Li‐O2 Batteries

“…Va rious strategies have been developed to stabilize Li metal anodes.O ne is an alloying strategy,which replaces Li metal with Li alloys,such as Li-Al, Li-Si, and Li-Sn alloys. [9] Very recently,areally convenient method has been presented. By contrast, forming ap rotective layer on Li metal anodes could prevent the direct interaction with electrolytes without capacity loss.L ee and co-workers reported ac omposite protective layer comprising Al 2 O 3 and polyvinylidene fluoride-hexafluoro propylene for Li metal anodes,w hich resulted in dramatic enhancement of cycling stability of Li-O 2 batteries.…”