[Translate to English:] © KIT/Amadeus Bramsiepe

How the e-car battery is going green

Jul 1, 2021

E-cars are intended to make mobility significantly greener. One of the challenges in doing so is sourcing the raw materials for the battery, such as lithium. But extracting lithium uses a lot of water. New processes can help in obtaining this alkali metal in more environmentally-friendly ways than before – in fact, even CO2-neutrally.

The overall environmental balance sheet of an e-car is still heavily dependent on the way in which the raw materials for the battery are obtained. And the demand for batteries is growing with the rise in demand for electric cars. According to calculations by the materials supply chain expert and consultancy Roskill, up to 2,200 GWh of battery capacity will be needed by 2030 for electric mobility, smartphones, laptops and the like.

Lithium for lithium-ion batteries, for example, is present in nature primarily in compounds – not as a pure element. The most important sources are currently lithium-containing rock and brine containing lithium salts. To date, the raw material for batteries has largely originated from Australia, where it is extracted in mines, or from Chile, Argentina or Bolivia. In South America, it is obtained from salars (salt flats). There, a lithium-containing brine is found below ground. The water is pumped to the surface and evaporates. What is left is a salt solution which is converted chemically into lithium carbonate. It’s an elaborate and lengthy process.

Green lithium from the earth

In future, lithium could be mined sustainably and CO2-neutrally from the Upper Rhine Plain near Offenburg in Germany – using geothermal systems. Researchers at the Karlsruhe Institute for Technology (KIT) have developed a process that can be used to filter out and process the lithium ions dissolved in the hot thermal water, until the lithium is usable. In this instance, lithium extraction takes just a few hours – in South America, extraction through evaporation takes several months, by contrast, and it can be delayed by weeks or months in the event of strong rains, for instance.

Geoscientist Jens Grimmer from KIT’s Institute for Applied Geosciences (AGW) estimates the amount of the raw material in the German countryside at up to 200 mg of lithium per liter of water. Along with this raw material for batteries, elements such as rubidium and cesium can also be obtained from the thermal water. They are used in laser and vacuum technology. According to KIT, up to two billion liters of thermal water is fed through the existing geothermal plants. After being used, it is sent back below ground – that way, no harmful materials are released, while at the same time power and heat are produced geothermally.

The Australian company Vulcan Energy has similarly presented a process, under the project name Zero Carbon Lithium, which is intended to cause no greenhouse gas emissions and use barely any water. Here, geothermal power plants that use the heat from the Upper Rhine Plain likewise filter lithium from the hot brine. The electricity needed for this similarly comes from renewable geothermal energy – making the raw material obtained CO2-neutral. The energy not used for lithium production is fed into the public power and heating grid. The lithium-containing water flows into an extraction plant, where the lithium is separated out from other elements dissolved in the water and subsequently refined. After being used, the thermal water is flushed back into the ground, as is usual with geothermal power plants.

The lithium content in the oceans is around five times as much as on land © Matthias Pens / Unsplash
The lithium content in the oceans is around five times as much as on land © Matthias Pens / Unsplash

Lithium from sea-water

In Saudi Arabia, researchers at the King Abdullah University of Science and Technology (KAUST) have developed a method for obtaining lithium for e-car batteries from sea-water. The lithium content in the oceans is around five times as much as on land, although it is found in exceptionally low concentrations of just 0.2 Parts per million (ppm). The scientists at KAUST are using an electrochemical cell to extract the lithium, containing a ceramic membrane made from lithium lanthanum titanium oxide (LLTO). Its crystalline structure allows the lithium ions to pass through small holes, whilst holding back other, larger metal ions. In several stages, solid lithium phosphate can be obtained in this way – sufficiently pure for the production of car batteries.

Doesn’t a process like this require a massive amount of energy? The Saudi Arabian researchers estimate that energy costing only five US dollars is needed to extract one kilogram of lithium from the sea. And after that, the residual water can be treated in desalination plants to become drinking water.

As yet, these processes are not in use in mass production of lithium. But if lithium can be produced in future in a C02-neutral way that spares resources, then driving your electric car will be twice the fun.

IAA MOBILITY is transforming itself from a pure car show to an international mobility platform with four pillars: The Summit, the Conference, the “Blue Lane” and the downtown Munich Open Space. Under the slogan of “What will move us next”, it stands for the digital and climate-neutral mobility of the future. From 7 to 12 September 2021, the car, bike and tech industries come together at IAA MOBILITY in Munich.