Effect of electrochemical dissolution and deposition order on lithium dendrite formation: a top view investigation

Abstract

Rechargeable metallic lithium batteries are the ultimate solution to electrochemical storage due to their high theoretical energy densities. One of the key technological challenges is to control the morphology of metallic lithium electrode during electrochemical dissolution and deposition. Here we have investigated the morphology change of metallic lithium electrode after charging and discharging in nonaqueous batteries by ex situ SEM techniques from a top view. Formation of the hole structure after lithium dissolution and the filling of dendrite-like lithium into the holes has been observed for the first time. In addition, an in situ SEM investigation using an all-solid Li/Li₂O/super aligned carbon nanotube set-up indicates that lithium ions could diffuse across through the surface oxide layer and grow lithium dendrites after applying an external electric field. The growth of lithium dendrites can be guided by electron flow when the formed lithium dendrite touches the carbon nanotube.