Large-Scale Production of Nanographite by Tube-Shear Exfoliation in Water

Abstract

The number of applications based on graphene, few-layer graphene, and nanographite is rapidly increasing. A large-scale process for production of these materials is critically needed to achieve cost-effective commercial products. Here, we present a novel process to mechanically exfoliate industrial quantities of nanographite from graphite in an aqueous environment with low energy consumption and at controlled shear conditions. This process, based on hydrodynamic tube shearing, produced nanometer-thick and micrometer-wide flakes of nanographite with a production rate exceeding 500 gh-1 with an energy consumption about 10 Whg-1. In addition, to facilitate large-area coating, we show that the nanographite can be mixed with nanofibrillated cellulose in the process to form highly conductive, robust and environmentally friendly composites. This composite has a sheet resistance below 1.75 Ω/sq and an electrical resistivity of 1.39×10-4 Ωm and may find use in several applications, from supercapacitors and batteries to printed electronics and solar cells. A batch of 100 liter was processed in less than 4 hours. The design of the process allow scaling to even larger volumes and the low energy consumption indicates a low-cost process.

Metal-free supercapacitor with aqueous electrolyte and low-cost carbon materials

“…The nanographite consists of micrometer-sized and nanometer-thin graphene-like flakes10, thus yielding a robust, smooth and fairly flexible electrode when combined with the NFC binder. The ACs are micrometer-sized clusters of irregularly shaped porous carbon particles.…”

“…. The nanographite was processed according to the method described by Blomquist et al 10. using thermally expanded graphite (SO#5-44-04) from Superior Graphite (Chicago, USA) as the initial material.…”

Nanofibrillated cellulose/nanographite composite films

“…This NG is produced by mechanically shearing a watergraphite suspension of approximately 2 wt% in a highpressure homogeniser. This large-scale production method of NG is well explained in Blomquist et al (2016). In their production approach, they have shown that they can mechanically exfoliate industrial quantities of NG using very low amounts of energy.…”

“…Nanographite (NG), in contrast, is a heterogeneous carbon material comprising a mixture of graphene, a few multi-layer graphene flakes, and graphite (Blomquist et al 2016;Andres et al 2014). It can be recognised as a highly functional conductive carbon nanoparticles that can be tailored for specific applications such as batteries, supercapacitors, graphite-based composites, printed electronics, sensors, energy applications, and life-science applications (Blomquist et al 2016). There is a high demand for producing renewable and sustainable nanocomposites with good electrical, thermal and mechanical properties.…”

Graphene Platelets and Their Polymer Composites: Fabrication, Structure, Properties, and Applications

“…For example, Paton et al reported that by using a mixer of 11 cm in rotor diameter and a container of 300 L (Figure c), the graphene production rate was promoted to 5.3 g h −1 , which is significantly higher than ultrasonication method. Blomquist et al recently achieved an extremely high graphene production rate of 500 g h −1 by using a digital Ultra Turrax disperser, which exfoliated thermally expanded graphite at 20 g L −1 in 100 L solvent. The rotation rate was up to 12 000 rpm, so an operation of 10 min can effectively produce a relatively large sum of GnPs.…”