Mass production of high-aspect-ratio few-layer-graphene by high-speed laminar flow

An efficient graphene production technique is essential to realize the commercial use of graphene. Liquid-phase exfoliation (LPE) of graphene is a low-cost method of graphene production. LPE is based on shear mixing or sonication in proper liquid. The applied force to graphite has not been optimized. Thus, the production rate and quality of graphene via LPE can be improved by controlling fluid dynamics in liquid. We demonstrate that the high-speed laminar flow generated by a pressure homogenizer effectively exfoliates large quantities of high-quality graphene. In a lab-scale trial, a production rate of 3.6 g/h of graphene in aqueous solution was achieved. In addition, the average lateral size of graphene obtained by the proposed method was larger than that by traditional sonication method. An industrial-scale machine could exceed a production rate of 1 kg/h, marking a significant step in the commercialization of graphene. We show that the graphene obtained using this method improves the mechanical properties of polymers more than graphene obtained via sonication.