(211b) Constructing Reliable Lithium Metal Surface with Functionalized 2D Mxene Mono-Layer As Coating

In order to achieve high-energy-density lithium-ion batteries to meet the rapidly growing market in electrical vehicles (EVs) and portable electronic devices, Li metal is considered as the most promising candidate as anode. However, the dendrite forming, low Coulombic efficiency, and unstable solid electrolyte interphase (SEI) pose big challenges in applying Li metal in batteries. To date several strategies on stabilizing the Li metal electrode have been attempted including but not limited to 1) add electrolyte additives and increase lithium salt concentrations, 2) use solid electrolytes with high ionic conductivity to mechanically inhibit the dendrite growth, 3) develop electrochemically stable artificial SEI, and 4) pre-store Li in stable hosts. In this presentation, I will talk about our recent progress in stabilizing the Li metal surface using two-dimensional MXene coating as anode in lithium ion batteries. First we will introduce covalent organic framework (COF) modified MXene mono-layer on Li metal. The lithiophilic coating promotes the uniform Li nucleation by homogenizing the Li ion flow and decreasing the nucleation barrier, resulting in a dendrite-free lithium metal anode. Second a dual-layer interphase that consists of an in-situ formed lithium carboxylate organic layer and ultra-thin BF₃-doped monolayer MXene was formed on Li metal surface. The honeycomb-structured organic layer increases the wetting of electrolyte due to the large surface area, leading to a thinner SEI. While the BF₃-doped monolayer MXene provides abundant active sites for lithium homogeneous nucleation and growth, resulting in about 50% reduced thickness of inorganic-rich components among the SEI layer.