▎ 摘　　要

Graphene, a two-dimensional nanomaterial, has shown tremendous promising applications in a broad range of fields. Mass production of defect-free graphene is a prerequisite for its applications. In this work, by using a needle valve, we propose a simple hydrodynamic-assisted exfoliation method to produce high-quality few-layer graphene flakes. The prepared graphene flakes, with an average layer of 5 (71% less than five layers) and a Raman D/G intensity ratio as low as 0.1, are free of defects and oxidation. The average thickness and length of the few-layer graphene flakes are 2.3nm (90%<4nm) and 1.9m (50% in the range of 1-7m), respectively. In a lab-scale trial, the concentration of graphene can reach 0.40g/ml under mild operating conditions (working pressure 20MPa, 16cycles), and the corresponding production rate is 0.40g/h. The hydrodynamic-assisted exfoliation by needle valve potentially offers a simple and efficient method for large-scale production of high-quality graphene.