Lithium-Powder Based Electrodes Modified with ZnI2 for Enhanced Electrochemical Performance of Lithium-Metal Batteries

Abstract

Lithium-powder electrodes, prepared via paste casting method using lithium powder and polyisobutylene (PIB) as a binder, were investigated for their electrochemical properties in lithium-metal cells. The electrode paste casting method allows preserving the spherical shape of lithium-powder particles during processing to electrodes. However, these lithium-powder based electrodes suffer from poor active material utilization, as electronic isolation of lithium particles during the lithium electrodissolution process was observed to occur. In order to improve the lithium inter-particle contact as well as the contact with the current collector, a simple and effective chemical modification of the lithium-powder based electrodes was considered. Using a cementation reaction with ZnI2, the growth of a Li-Zn intermetallic (“alloy”) between the lithium-powder particles and the surface of the lithium powder, lead to an increase of the active material utilization and overcame the side reactions due to lithium electrodissolution. Besides increasing the active material utilization, such simple chemical modification of the lithium-powder based electrodes improved the electrochemical performance resulting in more stable cycling behavior with low polarization and longer cycle life in both Li||Li-symmetric and Li||NMC 622 cells.