Polylatic Acid Nanofiber-Guided Uniform Lithium Deposition for Stable Lithium Metal Anodes

Lithium (Li) metal has been considered as potential choices for high-energy density batteries. However, the uncontrollable growth of Li dendrites and the infinite relative volume changes of Li anodes hinder its practical application. Herein we demonstrate a strategy to protect the Li metal anode by using a polylatic acid (PLA) nanofiber film. This polymer nanofiber film exhibits high ionic conductivity, flexibility, and chemical affinity, which enable the fast transfer of Li-ion and the feasibility to accommodate the volume changes of Li metal, and further resulting in a dendrite-free anode and stable interface. Numerous polar groups on the surface of PLA nanofibers can guide the orderly migration of Li ions. Besides, PLA nanofiber can form an artificial solid electrolyte interphase (SEI) layer by in situ reaction. Based on these advantages, we realize a high average coulombic efficiency (CE) of 95% within 150 cycles in a Li|Cu cell. When the LiCoO2cathode was assembled with PLA-protected Li anode, a high capacity retention (81%) within 100 cycles at 89mAg−1(1 C = 178mAhg−1) is obtained. This work highlights the advantages of an in situ polymer nanofiber artificial SEI layer in stabilizing Li metal anode and provides a fresh insight for the design of artificial SEI layer.