A Lithiophilic Scaffold of Three-Dimensional Free-Standing Silver Nanowire Aerogels for Stable Lithium Metal Batteries: In Operando xrd Investigation

Abstract

Although lithium metal is the most attractive anode materials in rechargeable batteries because of its high theoretical specific capacity (3,860 mAh g-1) and lowest electrochemical potential (-3.04 V), three problems including inhomogeneous lithium deposition, high chemical reactivity with electrolyte, and infinite relative volume expansion during lithium plating and stripping processes still hinder its practical applications. Several methods have been introduced to solve these problems including the use of artificial SEI layer, solid-state electrolytes, host materials. However, all such approaches mainly focused on the final stage of dendritic lithium with less consideration on the initial stage of lithium nucleation. Herein, we propose a new strategy to encapsulate metallic lithium within a lithiophilic scaffold of three-dimensional free-standing silver nanowire aerogel electrode (AgNWAs) which can control the position and morphology of plated lithium at the initial nucleation stage leading to a good coulombic efficiency of 98% after 100 cycles (400 h) in a corrosive carbonate-based electrolyte without any additives. The phase transformation mechanism of Li-AgNWA alloy half-cell and lithiated-AgNWA//LFP full-cell during lithiation/de-lithiation processes is also fundamentally investigated by in operando XRD measurement. In addition, the lithiophilic properties comparing between the bare AgNWAs, Li-AgNWA alloy, and planar Cu electrode are also confirmed by means of DFT calculation. This proposed strategy demonstrates the possible practical use of high-energy rechargeable lithium-metal battery in the next-generation energy storage technologies.