Our demand for batteries is skyrocketing, and raw materials are lacking. An unlikely source — trees — might help us.
The demand for batteries “is just mind-blowing,” Lauri Lehtonen says. He’s not wrong. With the EV transition under way, the world simply can not get its hands on enough batteries to meet the demands of the coming decades. So battery makers and car manufacturers are turning to just about any source of battery power they can find. That includes trees, which are 20-30% lignin. Inside lignin is carbon, a key ingredient for the anode of batteries. That’s where Lehtonen comes in. He’s the head of Lignode, the battery product from Stora Enso, a Finnish renewable materials company and “one of the largest private forest owners in the world.” As Lehtonen told the BBC, he’s been very busy of late figuring out how to deliver batteries from trees to an eager industry.
The Glue That Holds It Together
Lignin is a byproduct of the paper-making process, so for now at least, Stora Enso can source all the material it needs from its paper mills. In partnership with Swedish clean energy battery maker Northvolt, Stora Enso plans to mass-produce lignin batteries as soon as 2025. Northvolt opened its first “gigafactory” in Sweden in 2021 and has announced a second in Sweden and another in Germany in development. It has more than $30 billion worth of contracts to supply batteries to the likes of Volkswagen, BMW, and Volvo, so the manufacturer is eager to add to its roster of resources that includes recycled nickel, manganese, and cobalt.
While more environmentally friendly than gas-powered vehicles, EVs with lithium-ion batteries still have their own environmental extraction and waste issues. Graphite, a common anode ingredient, is often mined in ways that damage ecosystems and exploit workers.
“It is necessary to revolutionize battery technology in order to sustainably cover the needs for energy storage in an electrified future. In 10 years, the battery market is expected to grow tenfold,” Stora Enso says on its website.
What makes lignin even more promising as an anode ingredient is that it doesn’t need glue or a current collector to support a battery’s anode.
“Lignin is the glue in the trees that kind of glues the cellulose fibers together and also makes the trees very stiff,” Lehtonen told the BBC.
It can serve the same function in batteries.
Powering the IoT
Stora Enso is not the only company in that heavily forested part of the world using lignin for battery components. Sweden’s Bright Day Graphene makes graphene, the most electrically conducive material yet known, from lignin. Bright Day has partnered with clean energy battery maker Ligna Energy on lignin batteries to power IoT devices.
“Besides being biobased, our production method also allows us to produce a graphene with higher quality that most other graphene on the market,” Bright Day CEO Malin Alpsten said. “Higher quality means better electrical properties and high transparency for instance. We are still producing small quantities in our lab, but the next step is to scale up the production in an industrial pilot.”
In just two years’ time, Ligna Energy says, 150,000 IoT will come online every minute across the globe, leading to a need for 78 million batteries each day. They aim to make as many of those biobased as possible. They remain on the lookout for more raw materials that might serve as energy storage solutions and have a grant from Swedish innovation agency Vinnova to explore the potential of melanin produced by residues in the forest and paper industries.
Magda Titirici, a chemical engineer at Imperial College London, has been making electrospun mats of carbon skeletons from lignin that are “fantastic for batteries,” she told the BBC.
From a production standpoint, one of the biggest things lignin has going for it is that it does not need to be heated nearly as much as synthetic graphite to turn into a useful anode material. Titirici heats hers at 700 degrees Celsius, about a quarter of what synthetic graphite requires. Lehtonen says the resulting carbon structure Stora Enso produces is “amorphous” and “allows a lot more mobility of the ions in and out.” Because of this, Lignode can serve as the anode in a lithium- or sodium-ion battery that charges in as fast as 8 minutes.
Trees are certainly a more renewable resource than mined materials, but deforestation is already a problem, and we’re already enlisting new trees to capture carbon in other sustainability efforts. Will there be enough lignin to go around? Stora Enso has the largest production capacity in the world at 55,000 tons annually, and about 70 millions tons per year can be extracted worldwide from the existing paper industry, so it’s a good start.
“We work to ensure that forests and plantations are sustainably managed and that every effort is made to ensure more trees are grown than harvested,” Stora Enso says.
To make a difference, lignin doesn’t have to a key component of every battery made. It just needs to contribute to the overall mix. We’re going to need a lot more batteries to power a sustainable future, and lignin is going to help us do it. Otherwise, we’re missing the forest for the trees.