Preparation of large-area graphene film with oriented or unoriented structure by controlling self-assembly for lithium metal batteries

Large-area graphene films with defined uniformity, thickness and morphology are crucial for their applications in optoelectronic and photothermal devices. Herein, we demonstrate that oriented arrangement and ordered assembly of graphene oxide (GO) nanosheets in solution films can be realized to obtain the high-quality and large-area reduced GO (rGO) films. The key to the success of this process primarily lies in the control of GO solution shear force direction with array capillaries, achieving oriented arrangement of GO nanosheets in the solution film. Secondly, the control of GO nanosheet concentration and solution viscosity during solvent evaporation of solution film is key to achieve the ordered and disordered assembly of GO, featuring the smooth and wrinkled structure rGO films, respectively. Subsequently, the resultant smooth rGO film with ordered assembly exhibits excellent thermal conductivity and electronic conductivity (over 1800 S cm^-1). Meanwhile, the wrinkled rGO film with disordered assembly can be used as a coating layer on Al current collectors, demonstrating anti-corrosion properties and enhanced material adhesive stability. As a result, with such collectors, the high-voltage Li//NCM811 batteries show a 6-fold increase in cycle stability, and the lithium-sulfur batteries with high sulfur loading shows a 3-fold increase in cycle stability.