Study of Na Deposition Formation in Mixed Ethylene: Propylene Carbonate Electrolytes by Inert/Cryoelectron Microscopy

The sodium anode-free combines low-cost and high energy density, demonstrating a promising alternative to the Li battery counterpart. Nevertheless, the uptake of a sodium anode-free battery is greatly impeded by the uncontrollable dendrite proliferation upon the chemically active metallic Na. An insightful mechanistic understanding of Na deposition nucleation and growth behavior in ethylene carbonate and propylene carbonate (EC/PC, 1:1) is revealed via various inert and/or cryo-electron microscopy characterization techniques. The deposit morphology, size, and distribution were studied with different current densities and areal capacity. The Na deposit distribution changes from nonparametric distribution to normal distribution which can be attributed to the effect of interparticle diffusion coupling (IDP). The atomic information on the Na deposit was revealed via cryogenic transmission electron microscopy.