Innovative solutions for greener electric car batteries
Lithium-ion batteries currently contribute significantly to the emissions of electric vehicles. How can we reduce the environmental impact of batteries and effectively recycle their materials? Progress is being made in the field through the exploration of alternative raw materials, new manufacturing techniques, and recycling processes.
The green transition relies on a variety of climate-neutral solutions across industries such as manufacturing, energy, and transportation. Lithium batteries are currently the most crucial and expensive component of electric vehicles, yet paradoxically, they contribute to greenhouse gas emissions harmful to our society and the environment.
The Cradle-to-Grave model is used in the scientific footprint method called
Life Cycle Assessments
(LCA), which evaluates the complete environmental impact of products based on a chain of factors. For electric cars, it primarily involves the extraction of metals needed for battery production, cell manufacturing, vehicle usage during operation, and recycling processes.
Jonas Mindemark is a university lecturer in chemistry specializing in rechargeable batteries at Uppsala University:
– An electric car has the potential to have a low carbon footprint compared to, for example, a gasoline-powered car. However, this requires efficient battery production methods without 'dirty' energy, as well as charging electric vehicles with renewable energy sources. Sweden has the potential to lead in this regard, as a significant portion of our energy production is fossil-free.
Raw materials and manufacturing methods
Today, the production of lithium-ion batteries accounts for
61–106 kilograms of carbon dioxide equivalents
per kilowatt-hour (kWh) of battery capacity produced. As a comparison, the 2017 average was 150–200 kilograms of carbon dioxide equivalents per kWh of battery capacity. The reduction in carbon emissions is primarily due to more efficient battery manufacturing through larger factories and higher capacity. In battery production for electric cars, four main parts of the production chain are energy intensive.
– Firstly, there is raw material extraction, involving the mining of minerals required for batteries. Cobalt, for instance, has long been controversial because it is almost exclusively mined in the environmentally questionable conditions of the Congo. Efforts are now being made to replace cobalt in batteries with compositions containing more nickel, but the ambition is also to find alternative minerals with a lesser impact on the local environment.
– The second energy-intensive part in battery production is the metallurgical processes that involve high temperatures for materials, furnaces, and similar equipment. These processes can be challenging to reduce environmental impact unless fossil-free energy is used in mining and manufacturing industries.
In the production of electric car batteries, so-called 'dry rooms' are used, which are dry spaces with a controlled atmosphere that also require a significant amount of energy to remain free of humidity. Another environmentally crucial aspect is the production of the electrodes for the battery cells. For lithium-ion batteries, the process begins with a so-called 'slurry,' where the solid materials, or electrode particles, are mixed with binders and solvents, which are then dried onto a metal foil to create a solid composite material, Jonas Mindemark explains;
– This drying process requires a lot of energy, mainly due to the use of the solvent NMP, '1-methyl-2-pyrrolidinone,' a substance that is both hazardous to health and has a high boiling point, making the drying processes energy-intensive. To a significant extent, NMP is now being replaced with water, especially on the negative electrode side of the batteries where graphite is used. In the production of lithium batteries, this represents a clear improvement in both environmental and energy terms.
When a battery is newly manufactured, it undergoes a process called 'formation cycling,' or charge and discharge cycles, to ensure the functionality and performance of the battery before it leaves the factory.
– This is also an energy-intensive process, but it is also resource-wasting unless the energy generated during the discharge cycles is utilized. Battery manufacturers are continuously searching for methods to streamline production processes to minimize costs and carbon footprints. The use of renewable energy sources such as wind or solar power is an example of this.
Reuse and Recycling
Even though the production of electric vehicle batteries contributes most significantly to their carbon footprint, an increasing number of used batteries need to be efficiently and environmentally friendly recycled. One vital aspect of reducing the climate impact of electric vehicle batteries is to minimize the need for new raw materials in production. This is achievable by increasing the proportion of recycled metals from used batteries. But which materials are the most challenging to recycle?
– When it comes to graphite, whether it is synthetic or natural, it can vary in quality and structure, making it challenging to reprocess and reintegrate. In general, recycling of used electric vehicle batteries can be complex due to the variety of battery cells with differing chemical characteristics.
– The ion-conductive electrolyte is also challenging to recycle, both due to technical difficulties and limited economic viability. However, certain parts of battery packs are relatively easy to separate and recycle, for example casings, as well as copper and aluminum foils.
The most common metals in lithium batteries, such as cobalt, nickel, and manganese, are now possible to extract from used battery packs and reintegrate them in their original forms in the production of new batteries. There are also hopes to be able to do the same with lithium in the future. A significant focus in the battery industry is now on succeeding in regenerating the components of batteries that are the most energy-intensive to manufacture. Nevertheless, recycling is only part of the solution.
– As electric cars become increasingly popular, we will soon have a significant number of used batteries on the market. There is already talk of 'second life' use, which involves using secondhand electric vehicle batteries in other applications where energy density is less critical. An electric car battery with 50 percent capacity remaining can be suitable for stationary energy storage, helping to balance the power grid. This means that some batteries get a new lease of life before they end up in recycling, concludes Jonas Mindemark.
Rising raw material prices and environmental benefits have made the recycling of metals from used lithium batteries an increasingly important business. Recently, Swedish company Northvolt's subsidiary, Hydrovolt, opened a recycling facility in Fredrikstad, Norway, which is also the largest in Europe. The plant can recycle up to 95 percent of all materials in battery packs from electric vehicles, and the goal is to recycle 125,000 tons of batteries per year and use 50 percent recycled materials in battery cell production by 2030.