A hierarchical host microstructure enables regulated inner Li deposition for stable Li metal electrodes

Abstract

Dendritic lithium (Li) deposition is a critical issue hindering the development of next-generation high-energy-density Li metal batteries (LMBs). Confining Li deposition within a three-dimensional host is a general strategy to suppress the volume expansion of the Li electrode. However, precise control of continuous Li growth in the pore space of the host is rarely investigated, which is a crucial issue to enable a high utilization ratio of the hosted Li for practical LMBs. Herein, a novel hierarchical host structure possessing a multifunctional secondary porous structure to regulate the continuous Li growth with high uniformity and reversibility is proposed. The secondary porous structure consisting of carbon nanotubes, nickel and Li2O-enriched solid electrolyte interphase is in-situ generated via lithiation reaction of a modified nickel foam scaffold, exhibiting high lithiophilicity, fast Li+ transportation and charge transfer. The LMB utilizing Li metal electrodes hosted by this rational structure achieved a stable cycling over 300 cycles with a practical LiFePO4 positive electrode (~2.5 mAh cm-2) at 0.5C/0.5C in the voltage window of 2.5-4.4 V. This work provides a novel approach to designing the host microstructure for constructing more stable Li metal electrode in practical LMBs.