Enabling Reversible (De)Lithiation of Aluminum by using Bis(fluorosulfonyl)imide-Based Electrolytes

Aluminum, a cost-effective and abundant metal capable of alloying with Li up to around 1000 mAh g^-1 , is a very appealing anode material for high energy density lithium-ion batteries (LIBs). However, despite repeated efforts in the past three decades, reports presenting stable cycling performance are extremely rare. This study concerns recent findings on the highly reversible (de)lithiation of a micro-sized Al anode (m-Al) by using bis(fluorosulfonyl)imide (FSI)-based electrolytes. By using this kind of electrolyte, m-Al can deliver a specific capacity over 900 mAh g^-1 and superior Coulombic efficiency (96.8 %) to traditional carbonate- and glyme-based electrolytes (87.8 % and 88.1 %, respectively), which represents the best performance ever obtained for an Al anode without sophisticated structure design. The significantly improved electrochemical performance, which paves the way to realizing high-performance Al-based high energy density LIBs, can be attributed the peculiar solid-electrolyte interphase (SEI) formed by the FSI-containing electrolyte.