Ferrocene-Based Artificial Interfacial Layer for High-Performance Lithium Metal Anodes: Continuous Regulation of Li+ Diffusion Behavior

The diversified design of hybrid artificial layers is a promising method for suppressing the Li dendrite growth and maintaining high Colombic efficiency of lithium (Li) metal anode. Previously, various kinds of organic/inorganic hybrid artificial layers were constructed on the Li metal anode and possessed a positive effect on electrochemical performance. However, the tunable synthesis of artificial layers to continuously regulate the Li diffusion behavior remains a challenge. In this work, the Li diffusion behavior could be tuned by modulating the proportion of components (LiClO4, PMMA and ferrocene (Fc)) in the hybrid artificial layer (LF layer). After optimizing the proportion of each component, the resultant artificial SEI layer exhibits a high Li+ transference number (tLi+ = 0.66) and a high Young's modulus (4.8 GPa). Based on the excellent properties of the as-constructed Fc-based artificial SEI layer, a high-performance lithium anode with no volume effect and dendrite growth is achieved. The Li||Li symmetric cells with a Fc-based artificial SEI layer yielded a stable cycle performance for 1500 h with a high current density of 10 mA cm–2. The pouch cell with LF@Li anode coupled with high-loading LiFePO4 cathode (12.8 mg cm–2) exhibits excellent cyclic stability for 250 cycles with a capacity retention of 75% at 0.5C rate.