三维导电载体应用于钠金属负极的研究进展

Progress of 3D conductive framework for Na metal anode

  • 摘要: 钠金属因其成本低、自然丰度高、氧化还原电位低和理论比容量高等优点,被认为是高能电池的理想负极材料。然而,钠金属在充放电过程中易发生体积膨胀和产生钠枝晶,导致电池性能不断恶化,并引发安全隐患,严重阻碍了钠金属电池在实际中的应用。为了解决上述问题,国内外已进行了大量探索。其中,构建三维导电载体可以有效降低局部电流密度和成核能,抑制枝晶生长和减缓体积膨胀,在未来应用方面具有巨大的潜力。本文综述了近年来利用三维导电载体来提高钠金属负极电化学循环稳定性的研究进展并对三维导电载体进行了总结和分类。最后,从基础研究和实际应用两个方面讨论了三维导电载体材料在钠金属负极中的发展前景和未来研究方向。

     

    Abstract: Sodium is considered an ideal anode material for high-energy batteries because of its low cost, high natural abundance, low redox potential (−2.71 V vs SHE), and high theoretical specific capacity (1166 mA·h·g−1). However, due to the high reactivity, sodium rapidly reacts with the electrolyte to form an unstable solid electrolyte interface (SEI) layer during stripping/plating cycling. In addition, due to the large size change of sodium, the SEI layer repeatedly breaks and reassembles, resulting in the continuous consumption of sodium and electrolyte, as well as low coulombic efficiency and rapid capacity loss. Simultaneously, due to an uneven electric field distribution on sodium, numerous sodium dendrites generate during the repeated plating/stripping cycles. The growing Na dendrites easily pierce the separator, causing a short circuit and a series of safety issues. The above issues lead to the deterioration of battery performance and safety risks, thus considerably hindering the application of sodium metal batteries. Various studies have been conducted to solve these issues, including electrolyte engineering, artificial SEI layers, current collector and interlayer engineering, solid-state electrolyte engineering, and three-dimensional (3D) frameworks for sodium metal. Among various improvement strategies, the construction of a 3D conductive framework can effectively reduce the local current density, decrease nuclear energy, inhibit Na dendrite growth, and impede volume expansion, thus having a great potential in future applications. In this study, the current research progress in using various 3D conductive frameworks to improve the cycling stability of a sodium metal battery is reviewed, including carbon-based, metal-based, and MXene-based frameworks. Simultaneously, the pros and cons of different 3D conductive framework technologies in recent years are summarized and classified, and the electrochemical performance parameters of different 3D conductive frameworks for sodium metal batteries are compared. Finally, the development prospect and direction of 3D conductive frameworks in sodium metal anodes are discussed from basic research and practical applications. This review provides deeper insights into building more comprehensive and efficient sodium metal anodes. The 3D conductive framework technology can remarkably improve the cycle life and safety of a sodium metal battery. Multistrategy joint research methods will facilitate the practical applications of a sodium metal battery. Further exploration of the deposition behavior of sodium metal is required in the future, and we believe that it can definitely achieve commercial applications with continuous efforts.

     

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