In-situ construction of hybrid artificial SEI with fluorinated siloxane to enable dendrite-free Li metal anodes

Lithium (Li) metal anode holds great promise for high-energy-density rechargeable batteries. However, it suffers from the Li dendrites growth and uncontrollable side reactions with electrolyte due to the unstable solid electrolyte interphase (SEI) layer. Herein, we propose a facile strategy for the in-situ fabricate of organic-inorganic composite artificial SEI layers on Li surfaces, which consist of organic fluorinated siloxane and inorganic LiF-rich phases. The hybrid artificial SEI endows high mechanical strength (13.1Gpa) and Li + transfer number (0.62). Such robust SEI protective layers can not only guide uniform nucleation and deposition of Li metal by facilitating uniform Li-ion distribution, but also prevent unfavourable side reactions. Accordingly, the protected metallic lithium anode (PMTFPS-Li) anode enables stable Li plating/stripping performance in symmetric cells for more than 300 h at 4 mA·h/cm 2 under a high areal capacity of 4 mA/cm 2 . Moreover, the PMTFPS-Li/S cells could maintain more than 300 stable cycles at 0.5 C and the PMTFPS-Li/LFP cells present excellent cycling performance (400 cycles at 1 C) and enhanced rate capability (110.4 mA·h/g at 3 C). This work will inspire the design of artificial SEI on Li anodes for advanced Li metal batteries. • An organic-inorganic composite artificial SEI layer is successfully fabricated on the Li surface by a facile in-situ formation strategy. • The hybrid artificial SEI exhibits outstanding mechanical strength (13.1 Gpa) and high Li + transfer number (0.62). • Such robust SEI protective layers can guide homogeneous Li deposition and prohibit Li dendrite growth. • The full cells with PMTFPS-Li anodes deliver excellent cycling durability and higher rate performance.