A Superior Lithiophilic and Robust Composite Interface Layer for Dendrite- and Anode-Free Lithium Metal Batteries

Abstract

Anode-free lithium metal batteries (AFLMBs) are highly effective for enhancing the battery energy density. However, the unstable interface between the lithium metal anode and electrolyte compromises the reversibility of lithium deposition and stripping processes, ultimately limiting the cycle life of AFLMBs. To address this challenge, we developed a straightforward method involving coating a copper current collector with a composite layer. This layer comprises high-dielectric, high-modulus LiF nanoparticles combined with highly ion-conductive, robust polyoxadiazole (POD) material. Meanwhile, POD can be reduced to POD^n– at low potential. Hence, the resulting LiF@POD^n– composite film exhibits strong lithium-ion adsorption and a high lithium-ion transference number, facilitating improved lithium-ion transport, nucleation, and deposition. At a deposition capacity of 1 mAh cm^–2, the Cu/Li half-cell achieved an impressive Coulombic efficiency (CE) of 99.1% after 500 cycles. In subsequent full-cell tests utilizing a high-loading LiFePO₄ (LFP) cathode (12.3 mg cm^–2), the capacity retention remains substantial at 74.1% over 300 cycles. Similarly, in full-cell testing with a LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode at a 3 mAh cm^–2 areal capacity, the average CE reaches 99.5% over 150 cycles with a capacity retention rate of 82.3%. This unique polymer composite interface layer design provides an effective strategy for advancing AFLMB technology.