How can cobalt be reduced in EV batteries?

The electrification of transport is increasing. This means, more batteries are needed. However, some of these batteries contain an extremely problematic raw material: cobalt. PSI is researching alternatives.

Road transport is responsible for about a fifth of carbon dioxide emissions in the European Union. In order to achieve the goal of being climate neutral by 2050, the European Commission has imposed a sales ban on new petrol and diesel cars. As from 2035, all new cars entering the market are to produce zero emissions. However, internal combustion engines that run on climate-neutral fuels, so-called e-fuels, will still be allowed. This provision affects Switzerland, too, as this small market would no longer be profitable for European manufacturers of combustion engines for fossil fuels. The EU’s decision is therefore likely to further boost the trend towards battery electric vehicles in Switzerland.

Road transport is to become climate-neutral – the result is a growing demand for battery electric vehicles and hence for batteries. Currently, however, most batteries contain cobalt from Central Africa, where mining practices have been criticised for child labour, poor safety and environmental standards, and human rights violations. PSI is researching alternatives to reduce the amount of this problematic metal used in batteries. (Video: Paul Scherrer Institute/Benjamin A. Senn, Markus Fischer, Mahir Dzambegovic)

The environmental footprint of electric cars

When it comes to the environment, battery-powered vehicles have a lot going for them: their fuel efficiency is, in some cases, significantly higher than that of vehicles powered by internal combustion engines, which use fossil or synthetic fuels, or fuel cells. In other words, the energy they use can be converted without substantial losses. Depending on the model, battery electric vehicles have an energy loss of only 20 percent, whereas fuel cell vehicles, for example, waste up to 60 percent – mainly during the production of hydrogen.

The environmental “footprint” of battery electric vehicles is also significantly smaller. They produce no direct emissions, except through tyre and brake wear. Generating electricity has less of an environmental impact than producing and burning fossil fuels – even if the electricity used is not entirely clean. In addition, recycling makes it possible to reuse many components of the vehicles, mainly their batteries, once they reach “end of life”.

At the same time, however, manufacturing electric cars causes some 25 to 50 percent more damage to the climate than is the case with conventional vehicles – in particular due to the electronics and battery construction. Electric cars therefore start the race with a substantially larger ecological handicap than fossil-fuelled internal combustion engines. However, since they produce no direct emissions, they can keep catching up with every kilometre they travel. After a service life of about 200,000 kilometres, an electric car in Switzerland will have produced about 50 percent fewer greenhouse gases than a fossil-fuelled internal combustion engine.

Nevertheless, the negative effects of the batteries remain, because the raw materials required not only lead to political dependencies and environmental pollution, they are also criticised for being associated with child labour.

The problem with cobalt

The most common batteries used in today’s electric vehicles are so-called NMC accumulators, which consist of different amounts of nickel, manganese and cobalt. These elements form the basis of the cathode material – the part of the battery that is responsible for its performance. Cobalt is an important component because it increases the energy density of the batteries. It also increases the stability of the cathodes and prolongs the life of the batteries. However, cobalt is extremely rare. Only 0.004 percent of the earth’s crust consists of this rare metal. The Democratic Republic of Congo has the largest cobalt deposits in the world – about 70 percent of the world’s annual demand comes from this Central African country.

While most mining in Congo is industrial, artisanal mining is estimated to account for between 15 and 30 percent. These operations are carried out by independent miners, often women and children, who dig by hand for the coveted metal in tunnels that are at risk of collapsing, sometimes with inadequate equipment. The supply chains often lack transparency, mining conditions are problematic and despite declarations by the mining companies the exact origin of the raw material remains unknown. Industrial extraction can also lead to dust and sulphur dioxide emissions, as well as polluting drinking water, soils, fields and air.

The alternatives

Researchers at the PSI Laboratory for Battery Electrodes and Cells are looking for alternatives to reduce the amount of cobalt in batteries. This could be achieved by increasing the nickel content, for example. Nickel has an even higher energy density than cobalt, meaning that batteries with a higher nickel content could potentially store more energy.

Another alternative being researched at PSI are active materials for lithium-nickel-iron-manganese batteries. Here, iron replaces the cobalt in the cathode material. Thanks to the very high capacity and the high working potential of the material, a much higher energy density can be achieved than with conventional batteries.

To carry out their experiments, the PSI researchers mix the alternative cathode material, coat the electrodes with it and then assemble individual battery cells with these. The cells are wired separately and charged and discharged over and over again. This makes it possible to observe how the individual chemical elements in the cell react and change over time. The large research facilities at PSI also offer detailed insights into the internal workings of batteries. For example, synchrotron radiation from the Swiss Light Source SLS can be used to determine the structural changes that occur in lithium materials in batteries as these are charged and discharged.

There are several alternatives to cobalt. Each has advantages and disadvantages in terms of energy density, service life, charging time and safety, but also the availability of the raw material. It is important to develop a wide range of technologies so that these can be used to solve different problems in different applications. This would reduce the amount of cobalt needed and avoid being dependent on specific raw materials.

The video series Energy Future deals with everyday questions on the topic of Switzerland’s energy transition. Each short video focuses on one particular issue. Possible solutions are put forward taking the latest results of energy research at the Paul Scherrer Institute.