Formation of NaF‐Rich Solid Electrolyte Interphase on Na Anode through Additive‐Induced Anion‐Enriched Structure of Na<sup>+</sup>Solvation
Huaping Wang, Chunlei Zhu, Jiandong Liu, Shihan Qi, Mingguang Wu, Junda Huang, Daxiong Wu, Jianmin Ma
Abstract
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 PF 6 − in the Na + solvation sheath to facilitate PF 6 − 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||Na 3 V 2 (PO 4 ) 2 O 2 F full cells with high Coulombic efficiency (97 %) and capacity retention (91 %) after 200 cycles.