A 3D Hierarchical Host with Gradient-Distributed Dielectric Properties toward Dendrite-free Lithium Metal Anode

The conventional conductive three-dimensional (3D) host fails to effectively stabilize lithium metal anodes (LMAs) due to the internal incongruity arising from nonuniform lithium-ion gradient and uniform electric fields. This results in undesirable Li "top-growth" behavior and dendritic Li growth, significantly impeding the practical application of LMAs. Herein, we construct a 3D hierarchical host with gradient-distributed dielectric properties (GDD-CH) that effectively regulate Li-ion diffusion and deposition behavior. It comprises a 3D carbon fiber host modified by layer-by-layer bottom-up attenuating Sb particles, which could promote Li-ion homogeneously distribution and reduce ion concentration gradient via unique gradient dielectric polarization. Sb transforms into superionic conductive Li3Sb alloy during cycling, facilitating Li-ion dredging and pumps towards the bottom, dominating a bottom-up deposition regime confirmed by COMSOL Multiphysics simulations and physicochemical characterizations. Consequently, a stable cycling performance of symmetrical cells over 2000 h under a high current density of 10 mA cm-2 is achieved. The GDD-CH-based lithium metal battery shows remarkable cycling stability and ultra-high energy density of 378 Wh kg-1 with a low N/P ratio (1.51). This strategy of dielectric gradient design broadens the perspective for regulating the Li deposition mechanism and paves the way for developing high-energy-density lithium metal anodes with long durability. The gradient-distributed-dielectric carbon host (GDD-CH) is synthesized by introducing a grading content of polyantimonic acid (PAA) under the facile method of electrospinning technology and followed by carbonization progress. The gradient dielectric properties trigger a polarized electric field; the dipole moment is formed and arranged at the interface due to the directional migration of electrons and ions. This effectively regulates the Li-ion flux diffusion pathway, thus equalizing the ion concentration gradient within the host. As a result, the GDD-CH host enables dendrite-free Li plating/stripping behaviors for more than 2000 h at a high current density of 10 mA cm-2. image