A “flotation” strategy for tailoring the solid electrolyte interphase on 3D composite Li anodes

Abstract

In the realm of Li metal batteries, the deployment of three-dimensional (3D) composite Li metal anodes has emerged as a significant strategy for mitigating dendrite growth. However, the inadequate Li-atom affinity of 3D hosts and the heterogeneous solid electrolyte interphase (SEI) layer on 3D composite Li anodes lead to unsatisfactory electrochemical performance. A promising strategy to curtail dendrite growth is to construct a 3D composite Li anode with a lithophilic 3D structure and a tailored SEI. Herein, we develop a novel “flotation” strategy to construct these 3D composite Li metal anodes through a simple one-step method. During the molten Li injection process, lithophilic ZnO directs molten Li into the host, whereas ZnF₂, ZnP_xx, or ZnS reacts with Li to form relatively less lithophilic LiF, Li₃P, or Li₂S which “floats” to the surface to participate in the formation of a LiF-, Li₃P-, or Li₂S-rich SEI on the anodes. These anodes demonstrate a lithophilic 3D structure and a robust SEI, thereby stabilizing the anode–electrolyte interface. Consequently, these anodes demonstrate excellent stability with enhanced interface kinetics. When integrated into full cells with LiFePO₄ (LFP) cathodes, these anodes exhibit superior electrochemical performance. These findings underscore the efficacy of this strategy in achieving dendrite-free anodes, paving the way for their application in high-energy-density devices.