基于电解液调控的钠金属负极界面改性及性能研究

doi:10.15541/jim20250448

摘要/Abstract

摘要：

钠金属具有资源丰富、理论比容量高和氧化还原电位低等优势, 是锂金属负极的理想替代材料。然而, 钠金属负极在实际应用中面临枝晶生长和界面不稳定的严峻挑战。针对传统碳酸酯电解液存在溶剂化能垒高、界面动力学迟缓及枝晶易生成等问题, 本研究提出了一种“强-弱溶剂”协同调控策略, 通过在强极性碳酸酯溶剂中引入弱溶剂化能力的环醚类溶剂1,3-二氧戊环(DOL), 并结合PF₆^-阴离子的调控作用, 构建了稳定的钠金属负极界面。研究结果表明, DOL的结合能低, 显著降低了Na⁺的界面传输能垒, 使电解液电导率提高至9.31 mS·cm^-1, 并有效抑制了枝晶生长。在NaPF₆电解液体系中, PF₆^-因具有集中的最低未占分子轨道(LUMO)能级(−0.639 eV), 优先分解形成富含无机物的固体电解质界面层, 表现出优异的界面稳定性和循环性能。改性电解液在保持碳酸酯体系宽电化学窗口(约4.21 V)的同时, 显著降低了Na||Na对称电池的极化电压。基于Na₃V₂(PO₄)₃||Na结构的全电池在2C (1C=120 mA·g^-1)倍率下循环1600次后, 容量保持率高达92.1%。本研究通过协同调控溶剂化结构与阴离子化学特征, 为发展高稳定性钠金属负极提供了新思路。

关键词: 钠金属负极, 环醚, 溶剂化结构, 协同调控

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” 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 a concentrated lowest unoccupied molecular orbital (LUMO) energy level of −0.639 eV, preferentially decompose to form an inorganic-rich solid electrolyte interface (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

中图分类号:

TM912

梁沁沁, 蒙莹, 李丹丹, 韩方源, 喻敏, 唐彬, 罗宗昌, 李建新. 基于电解液调控的钠金属负极界面改性及性能研究[J]. 无机材料学报, 2026, 41(9): 1193-1200.

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, 2026, 41(9): 1193-1200.

图/表 7

图1 (a)不同溶剂的脱溶剂化能和(b)溶剂分子静电势分布

Fig. 1 (a) Desolvation energies of different solvents and (b) electrostatic potential distributions of solvent molecules THF: Tetrahydrofuran; FEC: Fluoroethylene carbonate; ESP: Electrostatic potential

图2 NP、NDP和HNP电解质的拉曼光谱图

Fig. 2 Raman spectra of NP, NDP and HNP electrolytes

图3 NP和NDP电解质的(a) LSV曲线和(b)塔菲尔曲线

Fig. 3 (a) LSV curves and (b) Tafel plots of NP and NDP electrolytes

图4 NP与NDP电解液中钠金属负极界面行为与沉积/剥离稳定性

Fig. 4 Interfacial behavior and plating/stripping stability of sodium metal anodes in NP and NDP electrolytes (a) Room-temperature EIS spectra of Na||Na symmetric cells; Current-time profiles of (b) Na|NP|Na and (c) Na|NDP|Na symmetric cells with insets showing impedance spectra of the corresponding cells before and after polarization; (d) Sodium plating/stripping cycling performance with different electrolytes and (e) the corresponding enlarged views; (f) SEM images of sodium metal electrodes after cycling in cells with different electrolytes. Colorful figures are available on website

图5 NP与NDP电解液中Na||Na3V2(PO4)3电池的电化学动力学与循环稳定性

Fig. 5 Electrochemical kinetics and cycling stabilities of Na||Na3V2(PO4)3 cells in NP and NDP electrolytes (a) EIS spectra; (b) Rate performance; (c) Charge-discharge cycling at room temperature; (d) Charge-discharge voltage profiles at different cycle numbers; Charge-discharge cycling at (e) 60 and (f) −20 ℃. Colorful figures are available on website

图6 DOL-NaPF6相互作用的理论计算与界面化学表征

Fig. 6 Theoretical calculations and interfacial chemical analysis of DOL-NaPF6 interactions (a) LUMO energy levels of PF6-, DOL and their solvation complex; (b) Binding energies between NaPF6 and DOL before and after interaction, along with the corresponding changes in the LUMO energy levels of NaPF6-DOL; (c) C1s, (d) O1s, and (e) F1s XPS spectra of interfacial Na electrodes of Na‖Na symmetric cells with NP and NDP electrolytes after 50 cycles

图7 NDP电解液中溶剂化结构调控及其诱导的钠金属负极稳定SEI膜形成的机理示意图

Fig. 7 Schematic illustration of solvation structure regulation and the formation of a stable SEI film on sodium metal anodes in the NDP electrolyte

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