Image credit: Stéven Renault, 2014, CC BY-SA IGO 3.0.
Lithium-ion batteries (LIBs) are normally considered an environmentally friendly technology, for example in electric vehicles where they are replacing climate gas spewing combustion engines. A widely unknown fact is that the production of these batteries causes a lot of pollution and climate gas emission too. I have talked to Dr. Stéven Renault, a researcher at Ångström Advanced Battery Center, Uppsala University (Sweden), who is trying to tackle this problem regarding the manufacturing process of LIBs.
Materials currently used in commercial LIBs are graphite and metal oxides such as cobalt oxide and manganese oxide. They are obtained via mining and subsequent chemical extraction. These processes create a lot of climate gas emission, pollution and waste. Metal oxides like cobalt oxide are also mainly mined in central Africa where unethical working standards and child labour are involved. In addition, it is very difficult to recycle lithium from these batteries when they reach the end of their life time.
The goal of Renaults research is to develop batteries from organic materials with a completely sustainable life cycle, in other words a ”green” battery. This means that the battery materials are produced from renewable sources like plants using environmentally friendly extraction methods. The contained lithium can also be easily recycled at the end of the batterys life span. This approach also focusses on using non-edible plants, for example trees, or parts of plants like the stems of crops to avoid conflicts with food production.
Nevertheless, Renault admits that green batteries still have some drawbacks, for example low energy densities. For this reason, they cannot yet compete with state-of-the-art materials (like graphite, cobalt oxide and manganese oxide) in mobile phones, laptops and electric vehicles. But the situation might change in the future if the lithium price keeps rising and lithium recycling becomes more attractive. In 2016 alone the price of lithium has increased by 14 %. Another issue is the lack of studies regarding battery safety. (We all have seen the images of burning mobile phones and laptops.)
To the question, if it is possible to buy these green batteries yet, Renault says that a Japanese company had unsuccesfully tried to commercialize them. But the competition of the standard batteries was too strong. Now a German company is working on green batteries for niche-markets where energy density matters less than in portable electronics and cars. This is where we will probably see the commercialization within the next two years.
Renaults own greatest accomplishment is the development of dilithium benzene diacrylate, a compound for use in LIBs that can be extracted from pine resins or alfalfa. When the end of the battery life cycle is reached lithium carbonate can be retrieved via ”thermal desctruction”, in other words burning, of the material. The lithium carbonate can then be used together with a precursor (benzene diacrylic acid) extracted from pine resins or alfalfa to create new dilithium benzene diacrylate to be used in another battery. This recycling process is shown in detail by the image above.
It will be very interesting to see when and in which form green batteries will be commercialized. Maybe we will be able to buy them for certain applications not too long from now.