Rational Design of Li‐Wicking Hosts for Ultrafast Fabrication of Flexible and Stable Lithium Metal Anodes

Abstract The ever‐increasing development of flexible and wearable electronics has imposed unprecedented demand on flexible batteries of high energy density and excellent mechanical stability. Rechargeable lithium (Li) metal battery shows great advantages in terms of its high theoretical energy density. However, the use of Li metal anode for flexible batteries faces huge challenges in terms of its undesirable dendrite growth, poor mechanical flexibility, and slow fabrication speed. Here, a highly scalable Li‐wicking strategy is reported that allows ultrafast fabrication of mechanically flexible and electrochemically stable Li metal anodes. Through the rational design of the interface and structure of the wicking host, the mean speed of Li‐wicking reaches 10 m² min⁻¹, which is 1000 to 100 000 fold faster than the reported electrochemical deposition or thermal infusion methods and meets the industrial fabrication speed. Importantly, the Li‐wicking process results in a unique 3D Li metal structure, which not only offers remarkable flexibility but also suppresses the dendrite formation. Paring the Li metal anode with lithium‐iron phosphate or sulfur cathode yields flexible full cells that possess a high charging rate (8.0 mA cm⁻²), high energy density (300–380 Wh kg⁻¹), long cycling stability (over 550 cycles), and excellent mechanical robustness (500 bending cycles).