Regulated lithium deposition behavior by an artificial coating of Cu foil for dendrite-free lithium metal batteries

Abstract

Although lithium metal with ultra-high theoretical capacity and the lowest reduction potential is considered as an ideal anode material for high energy density batteries, lithium metal batteries are hindered in practical applications by lithium dendrite growth due to inhomogeneous lithium flux and unstable electrode/electrolyte interfaces. Anode current collectors as the substrate for lithium deposition are critical to the stability of lithium metal anode (LMA); however, the simultaneous combination of guiding uniform lithium deposition (preliminary) and continuous protection of the lithium metal surface (posterior) remains a challenge for current collector development. Herein, an ultrathin polyacrylonitrile (PAN) modified layer was prepared on copper foil (Cu) by electrospinning technique, and they were used directly as the current collector for LMA. The PAN nanofiber network can homogenize lithium ions flux and promote uniform lithium deposition. Moreover, the PAN-modified layer can act as an artificial barrier to inhibit lithium dendrite growth and simultaneously mitigate the volume change of LMA. Benefiting the reasonable configuration, Li||PAN-Cu half-cell exhibits smaller cell polarization and a cycle life more than 2.5 times that of Li||Cu half-cell; Li@PAN-Cu||LiFePO4 metal batteries exhibit excellent compatibility in conventional carbonate-based electrolytes, with over 90% capacity retention for 200 cycles. Significantly, this study presents a new cost-effective approach of using a nanofiber network for current collector modification to achieve stable and long-lasting LMBs.