Highly Stable Lithium/Sodium Metal Batteries with High Utilization Enabled by a Holey Two-Dimensional N-Doped TiNb₂O₇ Host

Lithium/sodium metal batteries have attracted enormous attention as promising candidates for high-energy storage devices. However, their practical applications are impeded by the growth of dendrites upon Li/Na plating. Here, we report that holey 2D N-doped TiNb₂O₇ (N-TNO) nanosheets with high electroactive surface area and large amounts of lithiophilic/sodiophilic sites can effectively regulate Li/Na deposition as an interfacial layer, leading to an excellent cycling stability. The N-TNO interfacial layer enables the Li||Li symmetric cell to sustain stable electrodeposition over 1000 h as well as the Na||Na cell to stably cycle for 2400 h at 1 mA cm^–2 and 3 mA h cm^–2 with a depth of discharge as high as 50%. The full cells of the Li/Na anodes based on the N-TNO layer paired with the LiFePO₄ and NaTi₂(PO₄)₃ cathodes, respectively, show a very stable cycling over 1000 cycles at a negative-to-positive electrode capacity (N/P) ratio up to 3.