Transplantable Carbonaceous Li⁺ Filtrating Membrane for Lithium Metal Protection

Utilization of the lithium (Li) metal anode is seriously prevented by the undesirable side reactions with electrolyte solvents due to their mismatched energy gaps and easily lacerated SEI layer. In this work, we develop a transplantable carbonaceous membrane with a particular ability of filtrating Li⁺ ions by blocking organic solvents and use it as an independent protective component to isolate lithium metal anode from the electrolytes. This graphene-supported N-doped membrane (GNM) can separate organic carbonates of dimethyl carbonate (DMC) and diethyl carbonate (DEC) from H₂O-DMC/DEC mixtures by holding back the organic solvents. When this membrane is used in a Li-Cu cell, a high Li Coulombic efficiency (CE) of 98.5% is maintained in carbonate electrolyte over 400 cycles. Application of GNM in Li-O₂ full cell provides a sustainable use of Li metal for more than 200 cycles (2000 h) by keeping its shiny metal luster. Our results demonstrate that the use of an independent component with Li⁺ filtrating ability, such as the transplantable membrane of GNM developed in this work, should be a feasible remedy to protect Li metal anode in practical Li metal batteries.