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What if you could replace graphitic carbon in lithium-ion batteries with something more sustainable? Something made from trees? Lignode® by Stora Enso is a hard carbon that is a bio-based alternative made from lignin – an existing by-product in the production of cellulose fiber. Lignin is renewable, traceable and is already being produced in millions of tonnes in Europe – enabling the fast-growing battery business to become more sustainable.
It is necessary to revolutionise battery technology in order to sustainably cover the needs for energy storage in an electrified future. In ten years, the battery market is expected to tenfold. So, with increasing demands for electrification and rising standards of living, it’s essential that we find new and smarter technologies to meet the future.
One of the challenges of today’s lithium-ion batteries is the use of graphite. Graphite is a fossil carbon which is either mined or made from other fossil-based materials. The extraction through mining is often also done under less than satisfactory conditions, with social and environmental consequences.
At Stora Enso, we have therefore dedicated ourselves to coming up with a solution where graphite is replaced with hard carbon from lignin.
Develop tomorrow’s batteries together with us!
Trees are composed of 20-30% lignin, where it acts as a binder and gives wood its stiffness and resistance to rotting. It is one of the biggest renewable sources of carbon anywhere.
Being a side stream in the production of cellulose fiber, it is one of the biggest renewable sources of carbon anywhere. Most commonly side streams like lignin are burnt for energy, so by turning it into hard carbon we are making sure that more of the tree is put to good use.
Lignin (Stora Enso)
Lignin is separated from wood during the production of cellulose fibers.
Hard carbon powder (Stora Enso)
The lignin is refined into a fine carbon powder, which serves as an active material for the negative anode of the lithium-ion battery.
Hard carbon electrode
The hard carbon powder is then used to produce electrode sheets and rolls.
Finally, the hard carbon electrodes are combined with positive electrodes, separator, electrolyte, and other components into a lithium-ion battery.
A lithium-ion battery consists of a positive electrode, a cathode, and a negative electrode – called an anode. When a battery is charged, lithium ions in the cathode move into the anode, where they connect with the carbon particles and are stored until the battery is discharged – which is what happens when you use your electronical device.
Today, the material used in the anode is often graphitic carbon – which is a strictly layered material that can have slow charging times. We can replace this fossil-based graphite with hard carbon from trees, which brings with it both technical and environmental benefits.
Already a scalable model for commercial production
A scalable, renewable material from Europe
The growing battery market has a demand for high-quality and attractively priced materials. Hard carbon from lignin is readily available and can replace fossil-based anode materials which are often of limited supply. It is a rational and scalable way to switch to a renewable resource that is available in Europe.
Sunila Mill in Finland is the world’s biggest lignin producer
The annual capacity of producing kraft lignin at Stora Enso’s Sunila Mill is 50,000 tonnes per year. Lignin has been produced there at industrial scale since 2015, and the mill also produces 375,000 tonnes of pulp. Today it has been complemented with a pilot plant, where we’re turning lignin into hard carbon.
Click to learn more about Sunila pilot plant here.