Effects of an Organic Chemical Additive in Electrolyte on the Suppression of Lithium Dendrite in Lithium Metal Based Batteries

Abstract

Lithium (Li) metal has attracted much attention as an anode material for high energy density batteries due to the high theoretical specific capacity and low negative electrochemical potential of Li. However, the growth of Li dendrite on the metal electrode surface can lead to short circuits during the repeated electrochemical discharge-charge cycles. The control of lithium dendrite is one of the greatest challenges hindering the successful development of Li metal based batteries. In particular, Li metal is generally unstable against most chemical species and reacts with organic solvents as well as salts in liquid electrolyte. Furthermore, repeated stripping and deposition of Li may induce the uncontrolled dendritic growth of Li. To overcome aforementioned obstacles and difficulties in Li metal anode, we propose the use of an organic chemical as an electrolyte additive for controlling Li dendrite. The base electrolyte of LiTFSI/TEGDME was used for tests. With the addition of the additive, the Li grains formed, while the fiber-like Li dendrite formed in the Li/Li symmetric cell without the additive in electrolyte. Furthermore, the uniform solid electrolyte interphase (SEI) layer formed by the addition of the organic additive, leading to the suppression of Li dendritic growth and electrolyte decomposition. Accordingly, the Li/Li symmetric cell containing the additive operated for longer than 700 cycles, which was four time longer than that of symmetric cell without additive in the electrolyte, under the current density of 0.1 mA cm-2 when the areal capacity was limited to 0.2 mAh cm-2. Under the limited areal capacity of 1 mAh cm-2 at the current density of 0.5 mA cm-2, the cell containing the additive maintained the cycle life longer than 350 h. Further development of this electrolyte additive may enable the practical applications in Li metal based batteries such as Li-air battery.