Automated transfer of large-area defect-free graphene using a fluid transfer system

materials and coatings
Automated transfer of large-area defect-free graphene using a fluid transfer system (GSC-TOPS-265)
Gently removing graphene from its growth substrate and placing it onto an application substrate.
Overview
Currently, tools like forceps or glass slides are used to physically move or lift graphene layers in order to deposit them on application substrates. These tools, along with manual handling, apply concentrated pressures that may result in damage to the sensitive graphene layer. Additionally, they required manual labor limiting the scale of graphene production. The invention is a system that can be utilized as a post-processing system for graphene production allowing for automatic and gentle processing of graphene.

The Technology
The innovation is a series of inter-connected fluid reservoirs. The first reservoir comprises an etching agent that dissolves the growth substrate of a graphene sample. Subsequent reservoirs contain deionized water designed to wash off the etching agent. A graphene sample comprising a polymeric top coat, graphene layer, and growth substrate is floated in the first etchant reservoir. When the growth substrate has dissolved in the etchant fluid, the level of that reservoir is raised with additional etchant fluid. The rising etchant fluid level causes the etchant to flow into the next reservoir, creating a gentle current. The graphene sample floats along the current and is subsequently transferred into the next deionized water reservoir. The etchant is washed off in the deionized water. Once all the etchant is washed off, an application substrate is placed at the bottom of the deionized water reservoir. When the deionized water is drained, the graphene sample is mated with the application substrate via Van Der Waals forces. This innovation democratizes the the production of graphene, allowing it to be processed reliably and easily in house. This system can be utilized as a post-processing system for graphene production providing graphene substrates while keeping sensitive research and development safely in-house.
Carbon Nanotubes
Benefits
  • Scalable Graphene Production
  • Graphene less prone to damage

Applications
  • Graphene Production
  • Electronics
  • Sensors
Technology Details

materials and coatings
GSC-TOPS-265
GSC-18324-1
Similar Results
Examples of anticipated applications of holey nanocarbons: sensors, energy storage, water separation, etc.
Holey Carbon Allotropes
This invention is for scalable methods that allows preparation of bulk quantities of holey nanocarbons with holes ranging from a few to over 100 nm in diameter. The first method uses metal particles as a catalyst (silver, copper, e.g.) and offers a wider range of hole diameter. The second method is free of catalysts altogether and offers more rapid processing in a single step with minimal product work-up requirements and does not require solvents, catalysts, flammable gases, additional chemical agents, or electrolysis. The process requires only commercially available materials and standard laboratory equipment; and, it is scalable. Properties that can be controlled include: surface area, pore volume, mechanical properties, electrical conductivity, and thermal conductivity.
front image
Holey Graphene Mesh from Solvent-Free Manufacturing and Composites Thereof
The HGM or composite HGM developed is a novel nanocarbon-based architecture that (1) is prepared from dry processing from commercially available starting materials or readily prepared composites thereof; (2) exhibits micropores and mesopores due to the holey graphene sheets and their stacking; (3) exhibits micron- and macro-sized pores in the article. The method can produce a range of high-fidelity hole size, shape, and distribution on the graphene or composite articles. The disclosed laser-based method is easily scaled-up and automatable. The result is a novel ultra-lightweight graphene-based mesh structure with high electrical conductivity, thermal conductivity, high surface area, high through-thickness unimpeded ion transport, mechanical robustness. The HGM-based composites utilize HGM as a novel framework, matrix, or substrate for secondary components that are active for energy storage, catalysis, sensing, optical, filtration, and biological applications.
Provided by inventor
Carbon Bipolar Membranes for Solid-State Batteries
In traditional batteries with liquid electrolytes, e.g., lithium-ion, each battery cell must be individually sealed, packaged, and electrically connected to other cells in the pack. The cells in solid-state batteries on the other hand may be stacked on top of one another with only a separation layer in between, called a bipolar plate. These bipolar plates or membranes if thin enough must be electrochemically inert to the electrode and electrolyte materials while providing electrical connectivity between the individual cells. Here, NASA has combined advances in the preparation of carbon nanomaterials and solid-state batteries to create extremely lightweight bipolar plates and membranes. These bipolar membranes will enable high energy density solid-state batteries unachievable with typical bipolar plate materials like stainless steel, aluminum, aluminum-copper, or conductive ceramics. The carbon bipolar membranes may be fabricated in multiple ways including but not limited to directly compressing carbon powders onto an electrode-electrolyte stack or separately making a film of the carbon material and dry pressing the film between other battery layers. The new bipolar membranes have been demonstrated in high energy density solid-state batteries in coin and pouch cells. The carbon bipolar membranes are at technology readiness level TRL-4 (Component and or breadboard validation in laboratory environment)and are available for patent licensing.
Mars Habitat
Sucrose Treated Carbon Nanotube and Graphene Yarns and Woven Sheets
Various aerospace and terrestrial applications require lightweight materials with very high mechanical properties. Carbon nanotubes and graphene sheets have been found to be such materials. In addition, they have been found to have excellent electrical and thermal transport properties. However, retaining the excellent nanoscale properties, particularly mechanical and thermal transport, in bulk materials has proven to be challenging. In order for the nanotubes to be used in applications, they must be spun into yarn(s), sheet(s), and other macroscopic forms introducing relatively weak tube-to-tube and inter-bundle bonds. Also, the nanotubes tend to be entangled, and they therefore do not all contribute in load bearing. Weak coupling at tube and bundle interfaces also leads to mechanical and thermal transport that are much lower than would be expected from the nanoscale carbon nanotube or graphene properties. This invention is for consolidated carbon nanotube or graphene yarns and woven sheets via the formation of a carbon binder formed from the dehydration of sucrose. The resulting materials are lightweight and possess a high specific modulus and/or strength on the macro-scale. Sucrose is relatively inexpensive and readily available, leading to a cost-effective route for achieving bulk nanotube/graphene based multifunctional material formats.
Supercapacitors
Metal Oxide-Vertical Graphene Hybrid Supercapacitors
The electrodes are soaked in electrolyte, separated by a separator membrane and packaged into a cell assembly to form an electrochemical double layer supercapacitor. Its capacitance can be enhanced by a redox capacitance contribution through additional metal oxide to the porous structure of vertical graphene or coating the vertical graphene with an electrically conducting polymer. Vertical graphene offers high surface area and porosity and does not necessarily have to be grown in a single layer and can consist of two to ten layers. A variety of collector metals can be used, such as silicon, nickel, titanium, copper, germanium, tungsten, tantalum, molybdenum, & stainless steel. Supercapacitors are superior to batteries in that they can provide high power density (in units of kw/kg) and the ability to charge and discharge in a matter of seconds. Aside from its excellent power density, a supercapacitor also has a longer life cycle and can undergo many more charging sequences in its lifespan than batteries. This long life cycle means that supercapacitors last for longer periods of times, which alleviates environmental concerns associated with the disposal of batteries.
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