Sputter coating of lithium metal electrodes with lithiophilic metals for homogeneous and reversible lithium electrodeposition and electrodissolution
Marian Cristian Stan, Jens Becking, Aleksei Kolesnikov, Björn Wankmiller, Joop Enno Frerichs, Michael Ryan Hansen, Peter Bieker, Martin Kolek, Martin Winter
Abstract
Inhomogeneous lithium (Li) deposition leads to the formation of dendrites and “dead” Li, which is a limiting factor for the commercial success of Li metal batteries (LMBs). Herein, the sputter coating of Li metal electrodes by the sputter deposition method with lithiophilic metals, such as gold (Au) or zinc (Zn), was used in order to improve the electrochemical performance of Li metal electrodes. The structural characterization of such electrodes after the sputter deposition process indicated the presence of the corresponding Li-intermetallic phase (Li15Au4, LiZn) at the surface of the Li metal electrodes. Morphological investigations showed that the Li-intermetallic phases were able to steer the electrodeposition of Li beneath the Li-intermetallic coating, resulting in homogeneous dispersion of the Li deposits. The electrochemical measurements in symmetrical Li||Li cells also indicated reduced overvoltages. Up to a cycled capacity of 0.2825 mAh/cm2, these electrodes showed stable overvoltage for the lithium electrodissolution and electrodeposition process in comparison to pristine Li metal electrodes. Furthermore, in S8||Li cells, the overpotentials of sputter coated Li metal electrodes ([email protected], [email protected]) during operation are highly reduced compared to pristine Li metal electrodes. Thus, the results presented here, indicate that sputter coating of Li metal electrodes represents a promising approach to improve the performance of high energy LMBs through engineering of the Li metal interphase.