Study of the Electrochemical and Self-healing Processes of Galinstan as an Anode Material for Li-ion Batteries

Abstract

Alloy electrodes are attracting a lot of interest in the field of Li-ion batteries due to their high energy density. However, they suffer from large volume expansion and contraction during lithiation and delithiation, leading to rapid pulverization and disconnection. A strategy to avoid this is to use self-healing materials. Ga-based liquid alloys have been studied as self-healing electrodes because of their capacity to store Li and their liquid state at room temperature. The so-called “galinstan” (Ga0.77In0.15Sn0.08) exhibits the lowest melting temperatures and has also been used to add self-healing properties in composite electrodes. Nevertheless, its lithiation mechanism and its practical capacity still remain unknown. Also, the reversibility of the lithiation, which is crucial to ensure the self-healing properties offered by the liquid metal, requires investigation. In this work, electrochemical measurements were coupled with XRD and SEM analyses to better understand the redox processes, structural and morphological properties of galinstan as an electrode material in Li-ion batteries. It was shown that only Ga and In would react with Li to form LiGa and LiIn. The reversibility of these reactions and thus the self-healing ability of galinstan was demonstrated through observation of its liquid state before and after electrochemical cycling.