Has Graphene found some lead for its pencil?

Concrete and batteries?

Photo by Ramakant Sharda on Unsplash

Lead pencils, the ones we used to find in school with HB embossed on the side in a typical classroom, or 2B, 3B and so on, if you did an art class, defined a hardness scale. The softer the lead, the bigger the B and the darker the marks made.

There never was any lead in a pencil. They’re made from graphite and clay, with the softer ones containing more graphite.

What’s graphene then?

It’s a very thin layer of graphite, one of two naturally occurring carbon minerals (crystal structures) found on earth, the other much rarer one being diamond. And yes, if you squeeze graphite to about 200,000 times atmospheric pressure you can turn it into a diamond. That’s how lab grown, synthetic diamonds are manufactured.

Graphene was isolated in 2004, by Professor Andre Geim and Professor Kostya Novoselov at The University of Manchester. They used to hold Friday night experiment nights, where they played around, trying stuff for fun, which was not part of their day jobs. Probably quite popular with any anorak-loving students.

On one occasion, they removed some flakes from a lump of graphite using Scotch sticky tape. They immediately noticed that some flakes were thinner than others. They continued using the tape, peeling off layer after layer. When they analysed what they had left, they discovered a one atom thick material. It’s the thinnest compound known to exist, so thin, it only has 2 dimensions. Graphite is effectively a layer cake of graphene. Scientists had known of its existence for years, but no one had worked out how to extract it from Graphite.

Superpowers?

Why did the scientific world get so excited? Excited enough to award the two Manchester scientists the Nobel Prize in Physics.

Partly because some aspects of science fiction were showing significant promise of becoming scientific fact. Graphene is a carbon sheet 1 atom thick, one million times thinner than a human hair. It’s 200 times stronger than steel, but extremely light and flexible, which means it can be wrapped around other objects and materials. It’s also transparent as well as highly conductive of heat and electricity.

Applications appear to be numerous. In the biomedical world it could be programmed to attach itself to specific cancer cells. It can be stretched, twisted and rolled which helps create strong, bendable components including touchscreens. A highly electrically conductive graphene device, could accelerate the possibility of electric planes. Fully charging a phone might take seconds, a car, a few minutes. It’s almost completely impermeable which could help harness the storage and transport of future fuels. We might even come to wear graphene laced smart clothing.

And ………

Despite all this promise, graphene has largely been sitting on the shelf with the exception of the odd tennis racquet manufacturer, until now.

The world makes 4.4 billion tons of cement every year and pours 30 billion tonnes of concrete. Demand continues with no sign of slowing down soon, as poorer countries continue to build. If concrete was a country it would be the third biggest emitter of CO2 after China and the US. The main culprit is the chemical processes used to make cement, burning limestone and clay in a high-temperature kiln before grinding to a fine powder.

According to the Paris Agreement, (COP24) in 2015, cement production needs to fall at least 16% by 2030. With demand increasing, the target appears to be nothing more than a feel good number.

Some are taking it seriously and there have already been clever enhancements to the current process of making concrete. Once mixed, concrete has to harden, a process called curing. Traditionally, it’s done with water and takes 28 days. An alternative is to cure concrete with CO2, captured from other industrial processes and injected into the concrete, turning it into limestone. Another alternative is to add graphene to the mix.

Greener concrete

Nationwide Engineering, a spinoff from Manchester University have created a product called Concretene. By adding tiny amounts of graphene, the new material is 30% stronger than the standard product, significantly reducing the amount required to achieve the same structural integrity. It is also more durable and corrosion resistant. It can be used in exactly the same way, so no expensive add-on costs, just less required in the first place.

Last year a new gym floor in Amesbury, Wiltshire was laid with Concretene as a technology demonstrator, but it’s the contracts that the same company has with Network Rail which are more interesting.

The HS2 high-speed rail project will create 5 million tonnes of CO2, 1.4% of the UK’s annual emissions. Imagine the cost saving to the environment and the tax payer if the 19.7 million tonnes of concrete required is reduced by a third. It will also help Network Rail achieve their commitment to lower CO2 emissions by 11%.

If rolled out to the building industry globally, green concrete has the potential to reduce world emissions by 2%.

Better batteries

The problem with lithium batteries aside from the not insignificant environmental issues of mining the lithium, is they degrade with every charge, there’s a limit to how much power they can deliver and they need to charge slowly to avoid overheating.

They’re popular because of their high energy density, which has made them essential for electric cars, drones and smartphones.

With the addition of graphene, their capacity is further enhanced. They can charge more quickly and safely and their operational life can be extended. These upgrades to the existing tech are already becoming available.

There’s also a lot of energy being spent on battery technology research, including solid-state batteries where there is no liquid electrolyte between the two terminals. By mixing graphite with ceramic or plastic, a non-conductive material, the increased benefits of safety, longevity and super fast charging could see an end to liquid electrolytes, certainly in my life time.

Graphene doesn’t need graphite

Over 60% of the world’s output of graphite was mined in China in 2020. If graphene has finally found its mojo, our reliance on mining the raw material will change, especially as a number of alternative production methods with greener credentials are already available.

Chemical vapour deposition, an established industrial process, uses methane or liquids like ethanol in a chemical reaction to deposit carbon atoms onto a thin base of copper or nickel, which can be removed to access the graphene.

The Loop process uses microwaves to break methane into its constituent parts. Hydrogen is captured at the top and graphene the bottom of the reaction chamber.

Being able to breakdown methane from existing industrial processes such as landfill, water-treatment and oil wells without generating CO2 and instead harvesting hydrogen and graphene appears to be a perfect virtuous circle.

Finally, the flash process uses anything containing carbon, which is then squashed between two electrodes. Rice University in Houston, Texas have tried discarded food, old tyres and mixed plastic waste as well as more obvious carbonaceous products such as coal and carbon by-products from oil refining.

High energy pulses of electricity cause rapid temperature rises, breaking down the molecules in the sandwiched material. All the non-carbon is captured as a gas isolating the resultant graphene.

A future only discovered by imagination, having some fun and sticky tape.