Dendrite-free sandwiched ultrathin lithium metal anode with even lithium plating and stripping behavior

Thin artificial solid electrolyte coatings are effective to enhance the electrochemical performances and safety issues of lithium (Li) metal anode. However, massive and efficient fabrication of artificial protection layers on Li metal anode surface remains challenging. Herein, we describe a sandwiched Li metal anode fabricated through a continuous roll to roll calendering method to implant a thin and large-area carbon layer on Li metal anode surface at room temperature. Specifically, a carbon layer (~ 3 μm in thickness) can be entirely grafted from Cu substrate to 50 μm Li belt surface due to the stickiness of metallic Li. The carbon layer not only plays a critical role in providing rich nucleation sites for Li plating, but more importantly diminishes the metallurgical nonuniformity effects (slip lines) on stripping. Therefore, even Li plating/stripping morphologies are achieved and the as-obtained sandwiched Li/C composite anodes exhibit improved cycling stability both in Li | LiFePO₄ and Li | S coin cells and pouch cells. This continuous roll to roll calendering strategy opens a new avenue for grafting various thin artificial protection layers on Li metal surface for safe rechargeable batteries.