Computational and Experimental Investigation Towards a Stable Lithium Metal Anode

Abstract

Lithium metal is the ‘Holy Grail’ negative electrode of rechargeable batteries as it has the highest theoretical specific capacity and lowest electrochemical potential among all candidates. Next generation high capacity, high energy density battery systems, like lithium sulfur batteries, lithium air batteries, can never reach the level of commercialization without a safe and reliable lithium metal anode. Unfortunately, lithium metal cannot yet be safely implemented in commercial battery packs because of dendrite growth. Dendrite growth of these anode materials can cause short circuit within the battery, leading to dangerous fire and explosion in practical battery working conditions. In this work, through a combination of first principle computational calculations and experimental work, surface alloying lithium metal was found to be a promising approach to enable lithium metal to be directly employed as anode in future lithium metal batteries. The alloy-film protected lithium is effectively stabilized to electrodeposition over 700 cycles (1400 hours) of repeated plating/stripping at a practical current density of 2 mA cm-2. Ultra-long cycling life was realized for a Li4Ti5O12 electrode paired with such alloy-protected lithium metal negative electrodes. This work sheds light on a new and promising research field where the lithium metal can be stabilized by a surface layer/SEI with a low Li diffusion energy barrier.