Unraveling the Reaction Mystery of Li and Na with Dry Air

Abstract

Li and Na metals with high energy density are promising in application in rechargeable batteries but suffer from degradation in the ambient atmosphere. The phenomenon that in terms of kinetics, Li is stable but Na is unstable in dry air has not been fully understood. Here, we use in situ environmental transmission electron microscopy combined with theoretical simulations and reveal that the different stabilities in dry air for Li and Na are reflected by the formation of compact Li 2 O layers on Li metal, while porous and rough Na 2 O/Na 2 O 2 layers on Na metal are a consequence of the different thermodynamic and kinetics in O 2 . It is shown that a preformed carbonate layer can change the kinetics of Na toward an anticorrosive behavior. Our study provides a deeper understanding of the often-overlooked chemical reactions with environmental gases and enhances the electrochemical performance of Li and Na by controlling interfacial stability.

Refined Electrolyte and Interfacial Chemistry toward Realization of High-Energy Anode-Free Rechargeable Sodium Batteries

“…The above-mentioned result is aligned with the data from the isotope tracing experiment (Figure S20), indicating that carbonates are preferably generated in the CO 2 -dissolved electrolyte (where CO 2 comes from the decomposition of NCO). According to Hu et al., a SEI with a high fraction of Na 2 O/Na 2 O 2 tends to present a porous structure and a low mechanical strength under the Kirkendall effect (Note S9). Consequently, it is likely to crack and invite continuous parasitic reactions that consume both the active Na and electrolyte.…”

Synergistic Effect of CO2 in Accelerating the Galvanic Corrosion of Lithium/Sodium Anodes in Alkali Metal–Carbon Dioxide Batteries

“…In addition, the currently observed different sizes of the formed voids/cavities in the Li and Na interphase layer suggest that each metal has its own typical characteristics such as the distinct microscopic characteristics , (e.g., surface energy, self-diffusion barrier, etc. ), different mechanical properties, varying (electro)­chemical activities, and other noticeable crystallographic properties . It seems that tremendous efforts are needed to reveal the distinguished corrosion behaviors among the different alkali metals.…”

Self-sufficient metal–air battery systems enabled by solid-ion conductive interphases

“…5a), suggesting that the failure mechanism between Li and Na might differ. 32 XRD results (Fig. S6†) revealed that, unlike the Li anode, the Na anode is significantly more reactive to CO 2 , resulting in the formation of Na 2 CO 3 on the Na anode surface after cycling.…”