Ultrathin graphitic C3N4 lithiophilic nanosheets regulating Li+ flux for lithium metal batteries

Uncontrollable dendrite growth hinders the direct use of lithium metal anode in batteries even though it has the highest energy density of all anode materials. Li and N atoms have strong interaction and could form Li–N bond, promising for regulating Li-ion flux during the plating/stripping process. Herein, we successfully prepared ultrathin graphitic carbon nitride (g-C3N4) nanosheets with a thickness of ~ 1 nm and formed a g-C3N4 thin layer over the lithium metal anode. The abundant nitrogen species within g-C3N4 nanosheets could form Li–N bonds to powerfully stabilize the lithium-ion flux and enhance the affinity of electrodes with electrolytes. On top of that, the thin layer could act as an artificial solid electrolyte interface (SEI) to suppress lithium dendrite growth and enable stable Li plating/stripping over 350 h at a high current density of 5 mA cm−2 with a low overpotential of about 50 mV. The reported work demonstrates a promising strategy of the functional artificial SEI design for Li metal anodes.