Comparison of the growth of lithium filaments and dendrites under different conditions

Abstract

Although lithium dendrites have important implications on the safety and reliability of lithium-based batteries, an understanding of their growth mechanism is still lacking. Electron microscopy and in situ light microscopy were used to investigate the growth of lithium filaments and dendrites. Lithium was deposited by thermal evaporation in vacuum as well as electrochemically using two different electrolytes. Filaments grow in all three cases by an insertion mechanism, suggesting that neither a solid-electrolyte interphase (SEI) nor electrolytes are required to form lithium filaments. The role of the electrolyte becomes apparent in the detailed morphology of the deposits. These findings indicate that instead of ionic transport and electrochemistry, lithium diffusion and crystallization are key processes which need to be modified in order to control the growth of lithium dendrites.