Enhancement in cycle life of metallic lithium electrodes protected with Fp-silanes

Metallic lithium is a promising anode material whose application in rechargeable batteries has been limited by complicated chemical and morphological changes during cycling. These problems can be addressed by the introduction of protective coatings that help to improve the interphasial properties of these electrodes. In this study we used a dip-coating method to generate protective Fp-silane-derived coatings by direct reaction with the surface of metallic lithium. The effect of these coatings has been investigated by comparing the electrochemical performance of coated vs. uncoated electrodes through galvanostatic cycling and electrochemical impedance spectroscopy (EIS). A cycle life enhancement of up to 500% of that of uncoated lithium was observed. Additionally, we observed a trade-off between the value of the obtained stable capacity and the cycle life, which depended on the type of organic substituent on the silane moiety. These results imply that application-tailored protective coatings might, in the near future, enable the efficient use of metallic lithium electrodes in rechargeable batteries. •We developed new protective coatings for metallic lithium electrodes.•Fp-silanes coating agents with different organic substituents were investigated.•Galvanostatic cycling and EIS were used to evaluate performance of coated electrodes.•Enhancement of cycle life of up to 500% of coated vs. uncoated lithium in coin cells.•Mechanism of protection and coating formation are proposed.