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Toray Creates Ultra-Thin Graphene Dispersion Solution Offering Outstanding Fluidity and Conductivity

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Mar. 8, 2021

Toray Industries, Inc.

Tokyo, Japan, March 8, 2021 – Toray Industries, Inc., announced today that it has developed an ultra-thin graphene (see glossary) dispersion solution with excellent fluidity and electrical and thermal conductivity. Applications that could benefit significantly from the solution include battery and wiring materials and paints. Toray will keep pushing ahead with R&D on this breakthrough to accelerate commercialization.

Graphene is a sheet-like two-dimensional carbon material and is nanosized and ultra-thin. This advanced functional material is easy to align uniformly, contributing to its excellent conductivity and its barrier performance. Applying graphene or blending with other materials makes additional functions possible.

To date, Toray has developed technologies to create very thin, top-quality graphene from inexpensive graphite materials. The issue, however, is that thinner graphene is more likely to aggregate. In contrast, higher concentrations make graphene the more like a clay, impeding fluidity. It is hard to apply and mix graphene in clay form, so it is necessary to dilute and use it in low-concentration solutions. This has masked the inherent benefits of graphene.

Toray therefore developed a dispersion technology to control viscosity by adding a unique polymer material that suppresses aggregation from interactions between graphene. The result was a highly concentrated ultra-thin graphene dispersion solution with increased fluidity (see diagram). The fluidity is excellent, even in high concentrations. The solution is accordingly easy to handle and apply without dilution and more readily demonstrates its outstanding electrical conductivity and other advantages. The high dispersibility and ease of mixing make it simple to blend the solution with other materials.

A good application with the new solution would be as a conductive material for lithium-ion batteries. It can be mixed easily with cathode material, with graphene inserted between cathodes to boost conductivity. This approach lowers capacity losses from conductive pathways degrading during repeated charging and discharging, thereby extending battery life. The high-performance batteries of electric vehicles conventionally employ carbon nanotubes as conductive agents. Toray testing confirmed that the new solution offers 50% better battery life than carbon nanotubes.

It is also worth noting that applying and drying the solution laminates graphene to form a dense film. One use of the film could be printable electronics wiring that is highly durable and conductive without rusting like metal. Diverse other applications could include mixing the solution with anti-corrosion paints to block water and oxygen permeation that causes rust, thereby enhancing durability.

Toray will continue to develop revolutionary materials that transform societies in keeping with its commitment to innovating ideas, technologies, and products that deliver new value.

Graphene is a sheet-like material in which single carbon atoms (layers) bond in honeycomb-like structures. Multiple layers of sheets are also called graphene. Toray-developed graphene is a sheet with around 10 layers.


Figure: Proprietary dispersants improving graphene dispersion solution fluidity