Reinforced Composite Film on Lithium Metal Electrodes through Aryl Chlorosilane Treatment

Lithium metal has great potential to become the anode for the next generation of high-energy-density batteries because of high capacity (3860 mAh g^-1), lowest negative electrochemical potential, and low density. Low cycle efficiency and dendrite growth are two critical barriers for rechargeable batteries using Li metal as the anode, mainly due to the coupled mechanical/chemical degradation of the solid electrolyte interphase (SEI) layer formed on the Li metal surface. In this work, we found that a composite film of lithium aryl silanolate with uniformly distributed submicron LiCl-dominant particles can in situ form on the Li metal surface by treating Li with a single phenyl substituted chlorosilane. The synergistic effect of the high modulus of the composite film resulted from both well-dispersed LiCl particles and phenyl ring structures, and the extra reinforcement by the π-π interaction of aryl silanolate molecules that coated on LiCl particles and Li electrode surface endows the artificial surface coating film with high modulus and stability, and, thus, suitable as an artificial SEI layer. The coin cells using the lithium metal electrodes with this Lithium silanolate/LiCl particle composite coating layer showed an improved cycle efficiency and the extended life in a relatively harsh cycling condition.