Customizing Pore Structure and Lithiophilic Sites Dual‐Gradient Free‐Standing 3D Lithium‐Based Anode to Enable Excellent Lithium Metal Batteries

Developing 3D hosts is one of the most promising strategies for putting forward the practical application of lithium(Li)-based anodes. However, the concentration polarization and uniform electric field of the traditional 3D hosts result in undesirable "top growth" of Li, reduced space utilization, and obnoxious dendrites. Herein, a novel dual-gradient 3D host (GDPL-3DH) simultaneously possessing gradient-distributed pore structure and lithiophilic sites is constructed by an electrospinning route. Under the synergistic effect of the gradient-distributed pore and lithiophilic sites, the GDPL-3DH exhibits the gradient-increased electrical conductivity from top to bottom. Also, Li is preferentially and uniformly deposited at the bottom of the GDPL-3DH with a typical "bottom-top" mode confirmed by the optical and SEM images, without Li dendrites. Consequently, an ultra-long lifespan of 5250 h of a symmetrical cell at 2 mA cm^-2 with a fixed capacity of 2 mAh cm^-2 is achieved. Also, the full cells based on the LiFePO₄, S/C, and LiNi_0.8Co_0.1Mn_0.1O₂ cathodes all exhibit excellent performances. Specifically, the LiFePO₄-based cell maintains a high capacity of 136.8 mAh g^-1 after 700 cycles at 1 C (1 C = 170 mA g^-1) with 94.7% capacity retention. The novel dual-gradient strategy broadens the perspective of regulating the mechanism of lithium deposition.