Carbon nanotube (CNT) commercialization: past, present and future

Dr Khasha Ghaffarzadeh
Carbon nanotube (CNT) commercialization: past, present and future
CNTs are almost thirty years old already. In this time, they have gone through almost the entire hype curve, rising from their academic origins toward their peak of hype before nearly disappearing into the valley of disillusionment. CNTs have however, as the new IDTechEx Research report Graphene, 2D Materials and Carbon Nanotubes: Markets, Technologies and Opportunities 2018-2028 analyses, been making a quiet comeback and have now indeed entered a phase of volume growth.
In this article, we will review the evolution of the commercialization process of CNTs. We will do this by considering accumulated global capacity and price evolutions over the years. For more details, we refer to our report. This is a comprehensive report that provides segmented market forecasts, review of production process and applications and insights into key players in the business.
The hype curve for two prominent nanomaterials: graphene and carbon nanotubes. Multi-walled carbon nanotubes (MWCNTs) are now into their growth phase. Source: IDTechEx Research

Some background first

As in graphene and many other similar carbon additive materials, there is no single type of CNT but there are many. This diversity is shown in the chart below which maps the morphology of on-market CNTs based on their tube length and diameter.
Note that how the diameter ranges from around one nm towards several hundred, taking the CNTs from being singled-walled (SWCNT) towards multi-walled (MWCNTs) and carbon nanofibers. Similarly note that the range of available length, from a few micro meters all the way to 2 millimetres.
Each of these CNTs is a different material: it is produced differently; it is priced differently, it is processed differently, and it is used differently.
This diversity is also evident in the prices as shown below. We have removed the exact numbers, but you can that prices span an enormous six orders of magnitude, again re-emphasizing the point different CNTs are not equal. For exact values see our report.
In the remainder of this article, we will mostly discuss MWCNTs since they are the dominant form in the market. Near the end however I will highlight some key attempts seeking to also render SWCNTs more available and affordable.
Left: morphology of different CNTs morphologies on the market. Each box corresponds to a different CNT offered by a different company. The company (supplier name) is removed. Right: price position in $/Kg of different CNT type. We can that the price differences cover six orders of magnitude. For the details refer to Graphene, 2D Materials and Carbon Nanotubes: Markets, Technologies and Opportunities 2018-2028. Sources: IDTechEx Research.

Commercialization trajectory of CNTs

MWCNTs are mainly produced using the C-CVD process (catalytic chemical vapor deposition). This approach has been scaled up in different ways, e.g., floating catalyst, fluidized bed, etc. The key ingredients are temperature, carbon-containing gas, reaction time (residence time) and catalyst. The latter, which can be made of Co, Fe, etc- is critical to determining the morphology of the CNTs and the conversion yield of the process.
The evolution of accumulated global production for MWCNTs is shown below. I have selected to include this chart here because it tells the story of CNT commercialization well. Note here that the commercialization efforts start around 2005/2006. The super hype then sets in, leading to a rush to install capacity. This pushes the industry into a state of overcapacity, and still worse, pushes many to produce a CNT that is not good enough to meaningfully displace carbon black.
As a result, faced with disappointing prospects, some leave the business, leading to some correction in overall capacity. The global capacity then generally remains constant as some enter and leave. Importantly however, the utilization rate slowly begins to creep up.
Our analysis is now that the market has entered a period of volume growth. MWCNT use in conductive plastic applications is now well established and is expanding. It is also being added to new polymers like elastomers. More importantly, it is being used more in batteries. This is more important that the battery market is an escalator market in that it itself is poised for rapid growth thanks to uptake of electric vehicles demanding large batteries operating in high charge-discharge regimes.
In general, like most carbon-based materials, CNTs have diverse target markets, giving resilience to their prospects. The growth in demand, we assess, will manifest itself soon as increased capacity. This process already begun when a 400tpa facility came online in Korea a little over a year ago. This trend will continue.
Left: historical and projected price evolution of MWCNTs as a function time. The exact values have been removed in this article, but you can see that prices were reduced nearly by nearly a factor of 100. Right: global accumulated production capacity as a function time, telling the story of the market evolution. Source: IDTechEx Research
Like graphene, CNTs are often a substitute additive. As such, they must compete on price and performance against the reference market values set by the incumbent. This gives rise to a perennial downward cost pressure. The industry has therefore had no choice but to cut cost of production. And in that regard, it has had good success.
This is shown in the chart here too showing the price evolution of CNTs. The blue dots show historic prices whilst red ones are our future projections. The exact values are removed for the purposes of this article (see report), but the learning curve is steep with prices having fallen by 2 orders of magnitude.
This competition on price and volume has largely commoditized the MWCNT supply business. The cost of production will be influenced by processing know-how and technology including the catalyst technology but also by access to cheap inputs such as feedstock or energy.
When we speak of commoditization we do not mean that all differences in material quality have disappeared. Quite the contract. In fact, as started earlier in this article, many CNT types are on the market and the same is true of MWCNTs. The difference in quality, depending on application, will manifest themselves as small price differential. In that sense, despite high competition on price, the market retains its speciality chemical character.
MWCNTs are no longer a novel material but that not to say that innovation has stopped. Companies, for example, are now making good progress on growing long CNTs (up to 2mm) that can be drawn into macroscopic yarns for use in a range of applications. New functionalization and dispersing approaches are also constantly being disclosed.

What about other CNT types

SWCNT have superior performance on an individual tube basis given their higher surface-to-volume ratio. They are however more difficult and expensive to grow, come as mixed metallic and semiconducting types, and are much harder to disperse even though the wt% levels involved for the same or better effect might be much lower. These three attributes have combined to keep its market limited to some niche electronic devices.
Some companies are now seeking to change this by offering a more affordable and available SWCNT. In particular, a company in Russia has become the volume and price leader for SWCNT worldwide, pushing SWCNT closer to high-performance MWCNT in their market positioning. These SWCNT may compete with MWCNT as a substitute in some applications, but, more interestingly, they will open new applications despite their moderate-to-high impurity levels (in the as-grown versions). One interesting application is that they can enable coloured (vs. black) conductive adhesives. This is possible because the loading levels are so vanishingly low that colour pigments can be mixed and retain their effects. We assess that this and similar SWCNT will first find markets where they deliver this type of additional value to customer as they still cannot compete on cost directly.
For more information please see our report Graphene, 2D Materials and Carbon Nanotubes: Markets, Technologies and Opportunities 2018-2028. It provides the most comprehensive analysis of the CNT as well as graphene, markets. It covers production processes, applications, and more than 140 players. It also provides segmented market forecasts in tpa and value for MWCNT, SWCNT, and graphene platelet and film. It also analyses the business landscape from the prospective of capacity levels, etc.