To make the batteries of the future, R&D scientists are looking at materials sourced from nature. But can sustainable materials truly replace the battery materials we use today?

Batteries are one of the key pieces to achieve a more sustainable future. As more and more of the energy we use is from sustainable and renewable sources, we need batteries that can store and use that energy efficiently.  

One area where the demand for more and better batteries is soaring is electric vehicles. In 2023, the demand for batteries grew by 40% compared to the previous year, and the International Energy Agency reported that 95% of this growth was driven by electric car sales.

Electric vehicle battery demand | Source: IEA Licence: CC by 4.0

Despite their potential to enable a more sustainable future, battery production is not yet sustainable. For example, making lithium-ion batteries, which power laptops, smartphones and electric cars, requires mining rare metals such as lithium, cobalt and nickel — which can have devastating environmental effects such as deforestation and drought.  

An additional challenge is that some of the materials used in this type of batteries are toxic and difficult to recycle, or carry a risk of exploding if the battery is taken apart incorrectly.  Today, only about 5% of batteries are recycled. This is in part because at the moment it costs more to recycle them than to mine more raw materials to make new ones.  

There is an urgent need for new materials that are not just sourced sustainably but that can also keep up with the growing demand for more power and faster charging speed. Battery developers around the world are now looking at nature to make new battery materials that can meet these high expectations.

Battery materials from trees

An unexpected but very promising material to make the batteries of the future is lignin, a polymer found in the bark of trees that makes up approximately 30% of a tree. The rest of the tree is mostly composed of cellulose — the raw material used to produce paper.

Lignin is often thrown away in the waste streams of paper mills. Meaning we’re currently missing out on large amounts of a renewable material that could turn out to be much more valuable than we thought.  

So, what qualities make lignin a great candidate for battery materials? The key here is that lignin contains carbon, which is an excellent material for battery anodes. In fact, the lithium-ion batteries we use nowadays often have anodes made of graphite, a material composed of layered carbon atoms.

Lithium ions (purple) intercalated in graphite layers | QuantistryLab

It turns out that producing battery materials from lignin can be much more sustainable than creating synthetic graphite.

First of all, the industrial process to make synthetic graphite requires temperatures of up to 3,000 °C. According to Stora Enso, a Finnish company pioneering the development of lignin-based battery materials, the process to turn lignin into hard carbon structures suitable for use in batteries requires much lower temperatures in comparison.

Another advantage of lignin is that when it is transformed into hard carbon, the resulting material has an irregular structure, unlike graphite, which is formed by uniform layers of carbon atoms. According to the company, this structure can help the ions inside the battery to move from one electrode to another, which could make it possible to create batteries for electric vehicles that can be charged in as little as 8 minutes.

Incorporating lignin materials into batteries could also open the door to including other sustainable materials in the batteries of the future. For example, there is currently a lot of interest in high-energy, low-cost batteries that replace lithium ions with sodium ions.  

Unlike lithium, sodium is a very abundant element on planet Earth. Replacing lithium with sodium would eliminate the need for lithium mines along with the environmental damage they cause.  

As a bonus, some types of sodium-ion batteries can also work better with other more abundant materials, such as iron, instead of cobalt, copper or nickel, rare materials that require extensive mining.  

Lithium ions moving through graphite | QuantistryLab

The main challenge to making sodium-ion batteries is that sodium atoms are much larger than lithium atoms. The structure of the graphite anodes we use nowadays doesn't have big enough spaces in between the layers of carbon atoms for sodium ions to travel through them when the battery is being used or recharged.  

In contrast, carbon materials made from lignin have larger spaces between layers of carbon, which would allow sodium atoms to flow through. The specific properties of the material could then be engineered and fine-tuned by modifying the structure or combining it with other materials to optimize the performance of the battery.  

Optimizing battery performance

Battery developers have high expectations from new battery materials derived from trees. However, the main challenge for the industry today is to prove these claims true.  

There is a reason graphite has been the material of choice for lithium-ion batteries for the past 30 years. New anode materials made from lignin will have to compete with and outperform graphite in real-life applications, as well as prove their commercial viability to have a chance of becoming the new go-to material for batteries.  

The first batteries containing lignin-based anodes will be manufactured as early as 2025 by Swedish battery maker Northvolt. Until then, the question of whether this new technology can replace existing batteries will remain.  

To meet the growing demand for energy and sustainability, researchers around the world are working on testing and improving the performance of anodes made from new materials such as lignin.  

Multiscale simulations can be an extremely valuable tool for battery R&D, providing insights into the performance of multiple different materials and structures and ultimately saving significant amounts of time and resources in experimental research.  

For instance, simulations can offer unique insights into the mobility of ions in and out of an electrode. They can also predict essential properties of a battery material, such as the electrolyte viscosity or the electrode’s open circuit voltage.  

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