Formation of NaF‐Rich Solid Electrolyte Interphase on Na Anode through Additive‐Induced Anion‐Enriched Structure of Na+ Solvation. (16th August 2022) - Wang, Huaping
Abstract: High‐capacity sodium (Na) anodes suffer from dendrite growth due to the high reactivity, which can be overcome through inducing a stable NaF‐rich solid electrolyte interphase (SEI). Herein, we propose an additive strategy for realizing the anion‐enriched structure of Na + solvation to obtain a NaF‐rich SEI. The electron‐withdrawing acetyl group in 4‐acetylpyridine (4‐APD) increases the coordination number of PF6 − in the Na + solvation sheath to facilitate PF6 − to decompose into NaF. Thus, the NaF‐rich SEI with high mechanical stability and interfacial energy is formed to repress the growth of Na dendrites. With the 4‐APD‐contained electrolyte, the symmetric Na||Na cells show excellent cycling performance over 360 h at 1.0 mA cm −2 . Meanwhile, excellent stability is also achieved for Na||Na3 V2 (PO4 )2 O2 F full cells with high Coulombic efficiency (97 %) and capacity retention (91 %) after 200 cycles. Abstract : Owing to the anion‐enriched effect induced by 4‐acetylpyridine (4‐APD) additive, more PF6 − could enter the inner Na + solvation sheath to be decomposed into NaF on the Na anode surface, which could effectively repress the Na dendrite growth and boost the cycling performance of Na‐metal batteries.