Cementation Reaction of Lithium Powder Electrodes for Improving the Electrochemical Performances of Lithium-Metal Batteries

Abstract

Lithium metal is of particular interest for higher energy density Lithium Metal Batteries (LMBs) for example all-solid-state batteries, lithium/sulfur or lithium/oxygen batteries.1 Furthermore, there are several challenges to overcome, such as lithium dendrite growth, volume changes of the electrodes or low Coulombic efficiency, before reaching commercialization. With respect to these points, the initial morphology of the lithium metal could play an important role in suppressing the formation of lithium dendrites. However, the use of lithium powder is mainly limited to the prelithiation of high capacity electrodes.2 Using a common slurry casting method with polyisobutylene (PIB) as a binder3 allows the preparation of electrodes that preserve the spherical shape of lithium-powder particles. However, these lithium-powder electrodes suffer from poor active material utilization which is caused by the electronic isolation of such particles during lithium electrodissolution. In literature, studies could show an increase in mechanical surface stability after implementation of Li-rich composite alloy films on lithium electrodes.4 This approach (cementation reaction with ZnI2) was adapted to be suitable for lithium powder modification with the goal of the improvement of active lithium loss. The resulted growth of a Li-Zn alloy phase within the bulk lithium-powder electrodes and on their surface was found to improve the electronic contact between the lithium-powder particles. With this method, an increase in active material utilization could be achieved, resulting in enhanced cycling performances of LMBs with lithium powder anodes. Betz, J.; Bieker, G.; Meister, P.; Placke, T.; Winter, M.; Schmuch, R. Advanced Energy Materials 2018, 1803170.Holtstiege, F.; Schmuch, R.; Winter, M.; Brunklaus, G.; Placke, T. Power Sources 2018, 378, 522.Heine, J.; Rodehorst, U.; Qi, X.; Badillo, J. P.; Hartnig, C.; Wietelmann, U.; Winter, M.; Bieker, P. Electrochimica Acta 2014, 138, 288.Liang, X.; Pang, Q.; Kochetkov, I. R.; Sempere, M. S.; Huang, H.; Sun, X.; Nazar, L. F. Nature Energy 2017, 2, 17119.