(Invited) Corrosion Effects on Electrochemically Deposited Lithium Metal Electrode

Abstract

The lithium metal anode is essential for high energy density rechargeable battery due to its high specific capacity (3,860 mAh·g-1, or 2,061 mAh·cm-3)and low electrochemical potential (–3.04 V versus the standard hydrogen electrode). Although extensive studies have been performed to overcome dendrite growth and low coulombic efficiency problems associated with the practical use of lithium metal anode, there is a lack of comprehensive understanding of the storage properties and shelf life of lithium metal batteries, where chemical/electrochemical corrosion plays a critical role. We introduced the TGC (titration gas chromatography) method to quantify the corrosion rate of electrochemically deposited Li in liquid electrolyte system. It is demonstrated that lithium metal is mainly suffered from chemical corrosion by the liquid electrolyte instead of by electrochemical corrosion, that is, the direct charge transfer between lithium-electrolyte interphase. Besides, the corrosion rate of electrochemically deposited lithium in different electrolytes is further studied, where different electrolytes are found to introduce different corrosion rates. By taking into account the influence of different electrolytes on the SEI and Lithium morphology, we differentiate these two aspects, and the results in (1) The corrosion rate is mainly affected by the surface area of deposited lithium. The larger the surface area that the lithium has, the faster the corrosion rate will be; (2) The SEI components formed by different electrolytes on deposited lithium are similar, and different electrolytes will lead to the similar corrosion rate when the surface area is the same. Our findings provide valuable insights on the corrosion problem of electrodeposited lithium, where the surface area of deposited lithium turns out to dominate its storage properties.