Electrochemical exfoliation is a promising bulk method for producing graphene from graphite; in this method, an applied voltage drives ionic species to intercalate into graphite where they form gaseous species that expand and exfoliate individual graphene sheets. However, a number of obstacles have prevented this approach from becoming a feasible production route; the disintegration of the graphite electrode as the method progresses is the chief difficulty. Here we show that if graphite powders are contained and compressed within a permeable and expandable containment system, the graphite powders can be continuously intercalated, expanded, and exfoliated to produce graphene. Our data indicate both high yield (65%) and extraordinarily large lateral size (>30 μm) in the as-produced graphene. We also show that this process is scalable and that graphene yield efficiency depends solely on reactor geometry, graphite compression, and electrolyte transport.

The difficulty of scaling up the production of high-quality graphene nanoplatelets remains a major challenge for the graphene community and inhibits commercialization across a variety of market segments and applications. Here, we demonstrate a compressed, permeable reactor that produces graphene nanoplatelets via electrochemical exfoliation and controlled pressure. In contrast to prior controlled-volume reactors, the second-generation reactor allows for both direct control of pressure on the graphite source and arbitrarily large batch sizes. We have measured how graphene production is affected by the electrode type and arrangement (working electrode and counter electrode), reactor dimensions, and reaction kinetics. The data indicate that the reactor must be thin in at least one dimension to avoid diffusion limitations, but the long dimension can be scaled up without decreases in the yield. As in other batch processes, the highest production rate occurs in the initial stage followed by a plateau in conversion. An expandable graphite feedstock results in a substantial increase in yield compared to graphite flake feedstocks under identical reactor conditions.

The purpose of the paper is to demonstrate the effectiveness of high‐aspect ratio electrochemically exfoliated graphene (EEG) as a filler in high‐density polyethylene (HDPE); we use an industrially viable polymer processing technique (melt blending with melt recirculation) to ensure excellent dispersion and reinforcement at low loadings. The effects of nanofiller loading were evaluated for two different HDPE grades with two different melt flow indices (MFI) based on crystallization, tensile, and rheological properties. The findings indicate improvements in mechanical properties (tensile modulus and tensile strength) for all HDPE/EEG nanocomposite samples; however, the reinforcement was more pronounced at 0.2 wt% loading, indicating a transition from excellent dispersion at lower loadings to aggregated at higher loadings. The low and high MFI HDPE/EEG nanocomposites at 0.2 wt% EEG loading displayed an improvement of 31% and 40% in tensile modulus and 19% and 33% in tensile strength, respectively. The improved mechanical response with higher MFI nanocomposites is likely due to enhanced dispersion associated with the lower melt viscosity. Similarly, the rheological results also showed maximum increase in storage and loss modulus at a loading of 0.2 wt% EEG. In conclusion, EEG can be an effective filler if proper dispersion is achieved, which is challenging at high loadings.