Huang Longqing, Qiu Qian, Yang Ming, Li Haoxiang, Zhu Jialing, Zhang Wenjun, Wang Shuai, Xia Lan, Müller-Buschbaum Peter
Ningbo Innovation Team on New Energies and Marine Applications, Faculty of Maritime and Transportation, Ningbo University, Ningbo 315211, China.
Technical University of Munich, TUM School of Natural Sciences, Department of Physics, Chair for Functional Materials, James-Franck-Strasse 1, Garching 85748, Germany.
ACS Appl Mater Interfaces. 2024 Sep 4;16(35):46392-46400. doi: 10.1021/acsami.4c10970. Epub 2024 Aug 22.
Sodium bis(fluorosulfonyl)imide (NaFSI) electrolytes are renowned for their superior physicochemical and electrochemical properties, making them ideal for high-performance sodium-ion batteries (SIBs). However, severe oxidative dissolution of aluminum current collectors (commonly known as Al corrosion) in NaFSI-based electrolytes occurs at high potentials. To address this challenge, aiming to understand the Al corrosion mechanism and develop strategies to inhibit corrosion, we propose dual-salt electrolytes using 0.8 mol L (M) NaFSI and 0.2 M of a second fluorine-containing sodium salt dissolved in EC/PC solutions (1:1, v/v) to construct an insoluble deposits layer on the Al. Dual-salt electrolytes adopting a second sodium salt capable of passivating the Al collector have been extensively investigated through various techniques, such as cyclic voltammetry, scanning electron microscopy, chronoamperometry, X-ray photoelectron spectroscopy, and charge-discharge tests. Our findings demonstrate that introducing sodium difluoro(oxalato)borate (NaDFOB) into the NaFSI electrolytes inhibits Al corrosion, which is attributed to the formation of insoluble deposits of Al-F (AlF) and B-F containing polymers. Moreover, the capacity retention of Na||NaV(PO) (NVP) cells using the NaFSI-NaDFOB dual-salt electrolyte reaches 99.2% along with a Coulombic efficiency over 99.3% at a 1 C rate after 200 cycles. This research provides a practical solution for passivating Al collectors in SIBs with NaFSI electrolytes and promotes the development of sodium batteries with long calendar lifetimes.
双（氟磺酰）亚胺钠（NaFSI）电解质因其优异的物理化学和电化学性能而闻名，使其成为高性能钠离子电池（SIB）的理想选择。然而，在基于NaFSI的电解质中，铝集流体在高电位下会发生严重的氧化溶解（通常称为铝腐蚀）。为应对这一挑战，旨在了解铝腐蚀机制并制定抑制腐蚀的策略，我们提出了双盐电解质，该电解质使用0.8 mol/L（M）的NaFSI和0.2 M的第二种含氟钠盐溶解在碳酸乙烯酯/碳酸丙烯酯溶液（1:1，v/v）中，以在铝上构建一层不溶性沉积物。通过各种技术，如循环伏安法、扫描电子显微镜、计时电流法、X射线光电子能谱和充放电测试，对采用能够钝化铝集流体的第二种钠盐的双盐电解质进行了广泛研究。我们的研究结果表明，将二氟（草酸根）硼酸钠（NaDFOB）引入NaFSI电解质中可抑制铝腐蚀，这归因于形成了含Al-F（AlF）和B-F的聚合物的不溶性沉积物。此外，使用NaFSI-NaDFOB双盐电解质的Na||NaV(PO)（NVP）电池在1 C倍率下经过200次循环后，容量保持率达到99.2%，库仑效率超过99.3%。这项研究为使用NaFSI电解质钝化SIB中的铝集流体提供了一种切实可行的解决方案，并促进了具有长循环寿命的钠电池的发展。
