Li metal is an ideal, yet problematic anode for rechargeable batteries. Although it has been used for decades, little is known about its structure and solid electrolyte interphase (SEI), especially at the nanoscale. It is crucial to correlate the nanostructure change of the electrochemically deposited Li metal (EDLi) at different deposition conditions with the anode performance. By means of the powerful cryogenic transmission electron microscope (cryo-TEM), this work unravels the effect of the current density and deposition time on the nanostructure of the EDLi. It is shown that current density has a great influence on both the Li crystallinity and the SEI components. Methyl lithium (CH₃Li) is identified as a new SEI component. The heterogeneous characteristics of the EDLi is highlighted in a single EDLi ribbon. Based on the cryo-TEM observations, the mosaic model for SEI structure is further modified. These findings increase the knowledge base of the growth behavior of EDLi, provide important new insights on the SEI properties and highlight the connection between the nanostructure, performance and strategies.