Interface Modification and Performance of Sodium Metal Anode Based on Electrolyte Regulation

doi:10.15541/jim20250448

Abstract

Abstract: Sodium metal is an ideal alternative to lithium metal anodes due to its abundant resources, high theoretical specific capacity, and low redox potential. However, the practical application of sodium metal anodes is still hindered by severe challenges such as dendrite growth and interfacial instability. To address the issues of high solvation energy barriers, sluggish interfacial kinetics, and facile dendrite formation in traditional carbonate-based electrolytes, this study proposes a "strong-weak solvent synergy" strategy. By introducing a weakly solvating cyclic ether solvent, 1,3-dioxolane (DOL), into strongly polar carbonate solvents, combined with the regulatory effect of PF₆^- anions, a stable sodium metal anode interface was constructed. The results show that the low binding energy of DOL significantly reduces the interfacial transport barrier of Na⁺, increasing the ionic conductivity of the electrolyte to 9.31 mS·cm^-1 and effectively suppressing dendrite growth. In the NaPF₆-based electrolyte system, PF₆^- anions, with concentrated LUMO energy level of -0.639 eV, preferentially decompose to form an inorganic-rich SEI layer, exhibiting excellent interfacial stability and cycling performance. The modified electrolyte maintains a wide electrochemical window (~4.21 V) inherent to the carbonate system while significantly reducing the polarization voltage in Na∥Na symmetric cells. A full cell with the Na₃V₂(PO₄)₃||Na configuration demonstrates a high capacity retention of 92.1% after 1600 cycles at 2C rate (1C=120 mA·g^-1). This study provides new insights into achieving highly stable sodium metal anodes through synergistic regulation of the solvation structure and anion chemistry.

Key words: sodium metal anode, cyclic ether, solvation structure, synergistic regulation

CLC Number:

TM912

LIANG Qinqin, MENG Ying, LI Dandan, HAN Fangyuan, YU Min, TANG Bin, LUO Zongchang, LI Jianxin. Interface Modification and Performance of Sodium Metal Anode Based on Electrolyte Regulation[J]. Journal of Inorganic Materials, DOI: 10.15541/jim20250448.

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