One-Dimensional Porous Li-Confinable Hosts for High-Rate and Stable Li-Metal Batteries.

Abstract

Li-confinable core-shell hosts have been extensively studied because they mitigate Li dendrite growth and volume change by reducing the effective current density and storing Li inside the core space during consecutive cycling. However, despite these fascinating features, these hosts suffer from unwanted Li growth on their surface (i.e., top plating) due to the carbon shell hindering Li-ion movement especially at higher current densities and capacities, resulting in poor electrochemical performance. In this study, we propose a one-dimensional porous Li-confinable host with lithiophilic Au (Au@PHCF), which is synthesized by a scalable dual-nozzle electrospinning. Because of the well-interconnected conductive networks forming three-dimensional structure, porous shell design enabling facile Li-ion transport, and hollow core space with lithiophilic Au storing metallic Li, the Au@PHCF can suppress the Li top plating and improve the Li stripping/plating efficiency compared to their counterparts even at 5 mA cm-2, eventually achieving stable cycling performances of the LiFePO4 full cell and Au@PHCF-Li symmetric cell for over 1000 and 2000 cycles, respectively. Finite element analysis reveals that the structural merit and lithiophilicity of Au enable fast reversible Li operation at the designated core space of the Au@PHCF, implying that the structural design of the Li-confinable host is crucial for the stable operation of promising Li-metal batteries at a practical test level.