Metal carbodiimides-derived organic-inorganic interface protective layer for practical high energy lithium metal batteries

Abstract

The lithium metal batteries (LMBs) using lithium metal as the anode have attracted widespread attention as the next-generation high energy batteries. However, during the cycling process, the continuous chain side reactions between lithium and carbonate electrolyte and the growth of lithium dendrites would cause the failure of the batteries. In this paper, we propose that a metal carbodiimide (Ag2NCN)-derived organic-inorganic interface protective layer (MIPL) can effectively protect the lithium anode in practical LMBs. The MIPL has a double-layer structure with an outer layer of organic lithium carbodiimide (Li2NCN) and an inner layer of inorganic silver. The outer Li2NCN layer can stably adsorb ethylene carbonate molecules, promote the desolvation of lithium ions, and prevent the chain side reaction between lithium and carbonate electrolyte. Meanwhile, the inner silver layer promotes lithium metal nucleation, resulting in dendrite-free growth of lithium. Due to the advantages of MIPL, the practical MIPL-Li//NCA pouch cell with high energy of 357 Wh kg−1 (861 Wh L−1) has a stable lifespan for more than 100 cycles. This work not only provides a double-layer structure based on interface modification to protect Li anode, but also points out the possibility of carbodiimide compounds used in the field of LMBs.