High-Throughput Processing of Nanographite–Nanocellulose-Based Electrodes for Flexible Energy Devices

Abstract

The current work aims at understanding factors that influence the processability of nanographite−nanocellulose suspensions onto flexible substrates for production of conductive electrodes. A custom-built slot-die was used in a continuous rollto-roll process to coat the nanomaterial suspension onto substrates with varying surface smoothness, thickness, pore structure, and wet strength. The influence of a carboxymethyl cellulose (CMC) additive on suspension rheology, water release properties, and coating quality was probed. CMC addition reduced the suspension yield stress by 2 orders of magnitude and the average pore diameter of the coated electrodes by 70%. Sheet resistances of 5−9 Ω sq −1 were obtained for the conductive coatings with a coat weight of 12−24 g m −2 . Calendering reduced the sheet resistance to 1−3 Ω sq −1 and resistivity to as low as 12 μΩ m. The coated electrodes were used to demonstrate a metal-free aqueous-electrolyte supercapacitor with a specific capacitance of 63 F g −1 . The results increase our understanding of continuous processing of nanographite−nanocellulose suspensions into electrodes, with potential uses in flexible, lightweight, and environmentally friendly energy devices.

Nanocellulose for Paper and Textile Coating: The Importance of Surface Chemistry

“…The same continuous process was used to coat conductive nanocellulose/nanographite composites onto untreated greaseproof paper or pigment-coated paperboard. [190] Cellulose nanocrystals were used to enable the deposition from water of a polymer based on soybean oil: this material is very promising as a water barrier and is sustainable; however, it displays very poor water solubility. In this work, CNCs were first aminated by reaction with APTES (aminopropyltriethoxysilane).…”

“…The water vapour transmission rate (WVTR) of the multilayer coatings remained lower than the control PLA and LDPE coating even at a high RH of 90 %, confirming the usefulness of the PLA layer in protecting the nanocellulose layer from a high humidity environment. The same continuous process was used to coat conductive nanocellulose/nanographite composites onto untreated greaseproof paper or pigment‐coated paperboard [190] …”

Shear enhancement of mechanical and microstructural properties of synthetic graphite and ultra‐high molecular weight polyethylene carbon composites

“…N27SG (micrograph shown in Figure 1) has been described by the manufacturer as being able to be incorporated into final products with minimum shear suggesting that mechanical and electrical differences should be discernable when comparing CM billets to ECAP billets. While graphene is currently a highly desirable material to create composites with due to its exceptional properties, it is difficult to scale‐up production and many production techniques require toxic chemicals 28–33 . Nanographite is an alternate material that is easier to produce, is composed of both nanographene and multilayer graphene, and has electrical and thermal properties between graphite and graphene 28,29,34 .…”

“…While graphene is currently a highly desirable material to create composites with due to its exceptional properties, it is difficult to scale‐up production and many production techniques require toxic chemicals 28–33 . Nanographite is an alternate material that is easier to produce, is composed of both nanographene and multilayer graphene, and has electrical and thermal properties between graphite and graphene 28,29,34 . For those reasons, N27SG was deemed a suitable material to begin investigating the effects of ECAP on graphite‐UHMWPE composites.…”

Nanocellulose as a Sustainable Building Block to Construct Eco-Friendly Thermally Conductive Composites

“…Cellulose is the most abundant natural polymeric material on earth and can be obtained from plants, algae, fungi, bacteria, and marine creatures (tunicates), etc . Furthermore, nanocellulose, isolated from cellulosic sources at the nanoscale, has gained substantial interest in both the academic and industrial fields due to its biodegradability, renewability, biocompatibility, wide availability, low coefficient of thermal expansion, low density, high aspect ratio, and outstanding specific strength and modulus. − Especially, compared with traditional synthetic polymers, the one-dimensional nature of nanocellulose makes it difficult to fully encapsulate the thermally conductive fillers, which efficiently enhances the contact probability between adjacent fillers. Thus, after incorporating the same amount of fillers in the polymer matrix, thermally conductive fillers more easily form effective heat conduction pathways in the nanocellulose matrix, ultimately leading to a high thermal conduction efficiency of the as-prepared composites .…”