Au-coated carbon fabric as Janus current collector for dendrite-free flexible lithium metal anode and battery

Composite lithium metal anodes with three-dimensional (3D) conductive fabric present great potential to be used in high-energy-density flexible batteries for next-generation wearable electronics. However, lithium dendrites at the top of the fabric anode increase the risk of separator piercing and, therefore, cause a high possibility of short circuits, especially when undergoing large mechanical deformation. To ensure the safe application of the flexible lithium metal batteries, we herein propose a 3D Janus current collector by a simple modification of the bottom side of carbon fabric (CF) with a lithiophilic Au layer to construct highly flexible, stable, and safe Li metal anodes. The Janus Au layer can guide an orientated deposition of Li to the bottom of the CF. The lithium dendrite problem can be largely alleviated due to the lithium-free interface between the anode and separator, and meanwhile, the porous upper skeleton of the CF also provides large space to buffer the volume expansion of lithium metal. The resulting composite lithium metal anode exhibits a significant improvement in the life cycle (∼two fold) compared to the traditional top deposition of lithium metal. More importantly, assembled full batteries using the Janus anode structure exhibit high stability and safety during severe mechanical deformation, indicating the opportunity of the orientated deposition strategy to be used in future flexible and wearable electronics.