Dynamic construction of a composite solid electrolyte interphase for dendrite-free lithium metal batteries via lithium-antimony self-alloying

Lithium (Li) is considered the most promising anode material for Li metal batteries (LMBs) because of its extraordinarily high theoretical capacity and the lowest electrochemical potential among all potential anode materials. Despite their advantages, Li metal anodes (LMAs) still have several critical shortcomings (such as high reactivity and considerable volume expansion), which result in dendritic Li growth and fatal damage to the natural solid electrolyte interphase (SEI) of LMAs. These issues raise safety concerns and cause poor cycling stability of LMAs owing to their continuous parasitic reactions, which hinder their practical use in LMBs. Herein, by employing dynamic chemical reactions for Li-antimony (Sb) self-alloying and tetrahydrofuran-induced ion-conducting SEI fabrication, an artificial composite SEI is proposed to build a stable and dendrite-free LMA. The smooth and dense surface architecture of the electron-insulating and ion-conductive SEI in the LMA (Li@SbCl₃-20) not only promotes uniform Li-ion flux and current density but also prevents the direct Li-electrolyte contact, which results in a uniform and dense Li plating morphology underneath the SEI without side reactions. Moreover, symmetric Li@SbCl₃-20||Li@SbCl₃-20 cells demonstrate stable cyclability (over 400 h) and rate capability at metabolic current densities. When paired with LiNi_0.6Co_0.2Mn_0.2 or LiFePO₄, the Li@SbCl₃-20 full-cells achieved long-term cycling stability and rate performance.