A Superior Lithiophilic\nand Robust Composite Interface\nLayer for Dendrite- and Anode-Free Lithium Metal Batteries

Anode-free lithium metal batteries (AFLMBs) are highly\neffective\nfor enhancing the battery energy density. However, the unstable interface\nbetween the lithium metal anode and electrolyte compromises the reversibility\nof lithium deposition and stripping processes, ultimately limiting\nthe cycle life of AFLMBs. To address this challenge, we developed\na straightforward method involving coating a copper current collector\nwith a composite layer. This layer comprises high-dielectric, high-modulus\nLiF nanoparticles combined with highly ion-conductive, robust polyoxadiazole\n(POD) material. Meanwhile, POD can be reduced to POD<sup><i>n</i>–</sup> at low potential. Hence, the resulting LiF@POD<sup><i>n</i>–</sup> composite film exhibits strong lithium-ion\nadsorption and a high lithium-ion transference number, facilitating\nimproved lithium-ion transport, nucleation, and deposition. At a deposition\ncapacity of 1 mAh cm<sup>–2</sup>, the Cu/Li half-cell achieved\nan impressive Coulombic efficiency (CE) of 99.1% after 500 cycles.\nIn subsequent full-cell tests utilizing a high-loading LiFePO<sub>4</sub> (LFP) cathode (12.3 mg cm<sup>–2</sup>), the capacity\nretention remains substantial at 74.1% over 300 cycles. Similarly,\nin full-cell testing with a LiNi<sub>0.8</sub>Co<sub>0.1</sub>Mn<sub>0.1</sub>O<sub>2</sub> (NCM811) cathode at a 3 mAh cm<sup>–2</sup> areal capacity, the average CE reaches 99.5% over 150 cycles with\na capacity retention rate of 82.3%. This unique polymer composite\ninterface layer design provides an effective strategy for advancing\nAFLMB technology.