Operando study of lithium dendrite growth on graphite andoe By EC-AFM

Lithium dendrite growth is one of the most challenging problems affecting safety performance of lithium ion batteries (LIBs). It causes low Columbic efficiency as well as safety hazards for LIBs. Understanding the evolution process of Li dendrite growth at nanoscale is critical for solving this problem.

Herein, we report an in-situ electrochemical atomic force microscopy (EC-AFM) investigation of the initial Li deposition in EC and FEC-based electrolytes on graphite electrodes. Our results showed solid electrolyte interphase (SEI) formed from FEC-based electrolyte can suppress Li dendrite growth. FEC-based electrolyte induced formation of LiF-rich SEI films which were harder and denser than that formed in EC-based electrolyte. Combining with its better mechanical property and larger resistance, the SEI layer formed from FEC-based electrolyte is sufficient to slow down Li+ ions intercalation, prevent reduction of Li+ ions and Li deposition get electrons to deposit on the graphite surface. Our results demonstrated that EC-AFM is a powerful in-situ technique for the study of lithium dendrite growth.