Constructing Ag@SiO2–TiO2 Nanofiber Interlayers with a Three-Dimensional Lithiophilic Gradient Framework for an Ultrastable Lithium Metal Anode

Lithium metal batteries have become one of the most promising rechargeable batteries due to the ultrahigh theoretical specific capacity of the Li metal anode. However, the Li dendrite growth and volume change of the Li metal anode during repeated Li plating-stripping cycles restrict the practical viability. Herein, a unique lithiophilic gradient structure of uniformly incorporating Ag nanoparticles into a three-dimensional (3D) nanofiber framework with amorphous SiO₂ and TiO₂ hybrids was prepared by an electrospinning process and used as a multifunctional interlayer between the pristine separator and Li metal foil. The 3D framework not only possesses excellent flexibility but also alleviates volume changes, which can withstand massive Li loading and promote uniform Li⁺ distribution. In addition, the 3D lithiophilic gradient structure allows for regulable Li⁺ flux and suppresses Li dendrite growth. Impressively, the Li||Li symmetric batteries with Ag@SiO₂-TiO₂ interlayers exhibit a prolonged lifespan of 1500 h at 0.5 mA cm^-2 for 0.5 mAh cm^-2. The full cells coupled with the Ag@SiO₂-TiO₂ interlayer show a capacity retention rate of 94.6% after 1000 cycles and a high rate capability. This work provides promising guidance for the design of a gradient-distributed lithiophilic structure toward an ultrastable Li metal anode.