Rational design of polymer-based insulating scaffolds for high-capacity lithium metal batteries

Lithium metal is a promising anode material for next-generation high-energy–density secondary batteries. However, the uncontrolled growth of Li dendrites leads to infinite volume expansion and poor cycling stability. Herein, we propose a designable insulating polydopamine (PDA)-coated porous polytetrafluoroethylene (PTFE) scaffold. A porous PTFE (pPTFE) scaffold with micron-sized pores was fabricated, which provided bottom-up Li deposition owing to its insulating nature. Furthermore, the PDA-coated porous PTFE (PDA-pPTFE) scaffold provided internal space for Li growth and homogenized the Li-ion flux with abundant polar functional groups in the PDA, enabling "bottom-up" Li deposition within the scaffold without dendrite growth. This uniquely designed scaffold demonstrated excellent performance in half and symmetric cells with a small voltage hysteresis and dendrite-free Li plating. Moreover, when coupled with high-loading NCM cathodes (∼4 mA h cm−2), the PDA-pPTFE-based full cells exhibited stable cycling and rate performance, even with a low NP ratio of 1.0 at a rate of 1/3C, and exhibited a high energy density of 801 W h L−1. These results indicated the potential of the PDA-pPTFE scaffold as an anode material for highly stable next-generation rechargeable batteries.