Induction of planar Li growth with designed interphases for dendrite-free Li metal anodes

Abstract

Lithium metal is the ultimate anode candidate for high-energy-density lithium batteries because of its high specific capacity (3860 mAh g − 1) and low redox potential (−3.05 V vs. SHE). The nonuniform lithium ions flux and the highly reactive nature of Li metal, however, lead to continuous Li dendrite formation and dead Li growth. In this work, a separator modified by two-dimensional layered MXene (Ti3C2-T, T=-O and -F) and the solid-state electrolyte Li1.3Al0.3Ge1.7(PO4)3 (LAGP) is designed to induce planar Li plating with engineered interphases. The highly mixed conductive nature of LAGP/MXene facilitates the uniform transfer of the lithium ions/electrons. In addition, the -O and -F groups provide more plating sites and lower the Li's initial nucleation energy, which laterally induce planar deposition. The rearrangement of Li atoms inherits the atomic structure of MXene and significantly suppresses the formation of dendritic Li. Furthermore, the in situ formed Ge, Li3PO4 and LiF interphases, originating from the reduction of LAGP, help to stabilize the solid electrolyte interphase (SEI). The LAGP/MXene-modified separator reduces the voltage hypothesis and enables stable Li metal plating and stripping. In a full cell with a high loading of LiCoO2 (20 mg cm−2), the engineered separator exhibits stable cycling performance after 200 cycles. The novel strategy of regulating Li deposition and engineering SEIs is facile and efficient and can be applied to other alkali metal anodes.