In Situ Construction of Dual‐Functional UiO‐66‐NH ₂ Coated Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ to Achieve Lithium Metal Cells with Efficient Ion Transport in Quasi‐Solid Electrolytes

Abstract The NASICON‐type Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ (LATP) is a promising solid‐state electrolyte for lithium batteries due to its high lithium‐ion conductivity and air stability. However, its practical application in composite solid polymer electrolytes (CSPEs) is limited by high interfacial impedance, the polymer's inherently low lithium‐ion (Li ⁺ ) conductivity, and side reactions with lithium metal electrodes. U66N@LATP with a core–shell structure is synthesized by growing UiO‐66‐NH ₂ in situ on LATP nanoparticles and incorporating it into the PVDF‐HFP matrix to address these issues. The UiO‐66‐NH ₂ coating protects LATP from reacting with lithium metal electrodes and enhances Li ⁺ transport by providing a high Li ⁺ concentration environment. The U66N@LATP‐based Li‐symmetric cell exhibits superior stability in long‐cycle tests (>1000 h, 0.2 mA cm ⁻² ) compared to the sample without the core–shell structure. The assembled LiFePO ₄ (LFP) | CSPE | Li cell maintains a discharge capacity of 105.7 mAh g ⁻¹ with 93.8% capacity retention over 1500 cycles at 10 C. A pouch cell further validates the practical potential of U66N@LATP/CSPE in solid‐state lithium batteries. This study offers a simple and efficient core–shell architecture design strategy to mitigate LATP side reactions and reduce the interfacial impedance, thereby improving the overall performance of the electrolyte system.