A CF4 plasma functionalized polypropylene separator for dendrite-free lithium metal anodes

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Vol. 11; no. 14; pp. 7545 - 7555
• Main Authors: Cao, Shengling, He, Xin, Chen, Manlin, Han, Yu, Wang, Kangli, Jiang, Kai, Zhou, Min
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 04.04.2023
• Subjects: Anodes; Batteries; Dendrites; Electrode materials; Energy storage; Fluorine; Functional groups; Ions; Life span; Lithium; Lithium fluoride; Lithium ions; Polypropylene; Separators; Solid electrolytes; Storage systems; Wettability
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d2ta09763j

Lithium metal is recognized as a promising anode material for next-generation high-energy-density batteries, but uncontrollable lithium dendrites inhibit their further applications. In this paper, fluorine-containing functional groups were grafted on a commercial polypropylene (PP) separator by a simple and efficient plasma functionalization technique. The grafted polar groups enhance the affinity of the PP separator for Li-ions, thus resulting in improved wettability and ion conductivity as well as an enhanced lithium-ion transference number of the separator. Moreover, the introduced fluorine-containing functional groups participate in the formation of a LiF-rich solid electrolyte interface (SEI) film, which regulates the uniform deposition of lithium ions and inhibits lithium dendrite growth. As a result, Li‖Li symmetric batteries equipped with fluorinated PP separators exhibit a long lifespan of nearly 7000 h (1 mA cm−2, 1 mA h cm−2) with a low overpotential of 48 mV. This work introduces a simple method to induce the formation of a LiF-rich SEI film, which can be extended to a variety of energy storage systems and provides new routes for the construction of high-performance energy storage technologies.