Towards a circular economy for batteries
Electric mobility is a strategic pillar for the mobility shift towards more sustainable and environmentally friendly technologies. Batteries for vehicles are a key technology for the success of electric mobility. But as the number of electrically powered vehicles increases, so does the need for an efficient and environmentally friendly recycling of end-of-life vehicles and their components. In this paper, the researchers of the Fraunhofer Project Group for Materials Recycling and Resource Strategies IWKS point out the most important facts, challenges as well as solutions.
The electric mobility market is growing
Since 2011, the number of electric cars in Germany has increased from 2,307 to 53,861 in 2018 - according to plans by the German government, one million electric cars are to be on German roads by 2020 (1). The demand for high-performance batteries such as lithium-ion batteries is therefore growing at the same rate. To meet this demand, an efficient recycling of used batteries is essential. According to forecasts, up to 500 million lithium-ion battery cells could be disposed of in 2020 in the USA alone (2). Depending on technological developments, this figure could increase to up to 4.5 billion battery cells by 2030 - a rapidly growing waste stream. This applies not only for example to batteries damaged in an accident, but also to intact used batteries. With less than 80% of their original charging capacity, traction batteries normally reach their end of life, as the range of the vehicle rapidly decreases (3). Even if batteries are used in second and third life applications after their first use, sooner or later they will have to be disposed of. The aim is to recover and recycle as many of the included materials as possible as part of a closed circular economy. This is also laid down in the Batteries Act (BattGDV), according to which a recycling rate of 50 percent of the average mass of other used batteries (which includes Li-ion batteries) has been mandatory since 2011 (4). The batteries can be collected either via the various take-back systems or directly via a manufacturer's own system. The collection rate to be met is currently around 45 percent and is calculated on the basis of the weight of spent batteries collected in the current calendar year in relation to the weight of batteries sold by manufacturers in the respective calendar year as well as in the two previous calendar years (5).
No mobility shift without raw materials
In order to provide the high energy required for use in electric cars, high-performance batteries are made of special materials that contain various critical raw materials. These include above all lithium, cobalt, nickel and graphite. Demand has risen enormously in recent years: More than 40% of the cobalt produced worldwide is used to manufacture lithium-ion batteries (6). Cobalt is only mined in a few countries of the world, including DR Congo, Russia, Australia and Cuba, as there are very limited reserves. Increased demand, coupled with dependence on imports from the mining countries, has led to a massive increase in prices. Since mid-2016, the price of a ton of cobalt has almost multiplied by four from USD 23,000 to around USD 90,000 in just two years. Among other things, the industry is responding by further reducing the cobalt content in order to cut costs. However, this is not possible indefinitely.
Efficient recycling contributes to increasing the sustainability of electric mobility
The aim of the research work is to contribute to a sustainable development in the sense of an ecologically intact, economically successful and socially balanced world. The recycling of traction batteries from electric vehicles will gain massive importance in the coming years. The current capacities will be overtaken in the near future by the quantity of disposed batteries. In general, the researchers of the Fraunhofer Project Group IWKS see great potential on the market for further developing a recycling of used batteries from electric cars - ideally right up to a complete recycling. However, recycling batteries is not new and is already being implemented on an industrial scale. There are various approaches to this:
- Mechanical recycling: shredding and grinding, separation of fractions, recovery of concentrates
- Pyrometallurgical recycling: melting of batteries for recovery of cobalt, nickel and copper
- Hydrometallurgical recycling: dissolution of fractions and chemical recovery (precipitation, electrochemical separation) of elements
The individual procedures are often combined in order to achieve better results. However, the use of energy and process equipment is still quite high, depending on the process. In addition to already established processes for the recovery of copper, aluminum, nickel, cobalt and manganese, there is also a need for more efficient processes to recover other components such as graphite or lithium. Lithium batteries are already profitable waste streams because of the valuable metals they contain (cobalt and nickel). However, in terms of materials recycling, the aim should not only be to recover the metals, but also to recycle the higher-quality functional materials (battery electrodes). Only in this way can electric mobility become a truly sustainable alternative to conventional drive technologies (in addition to the provision of climate-neutral electricity). To this end, the entire battery recycling chain must become more efficient. In particular, the recycling of electric car batteries in Germany still faces the following challenges:
- End-of-life vehicles are exported to other countries (sometimes illegally) instead of being recycled in a targeted manner in Europe.
- There is still a high degree of uncertainty about the number of disposed batteries. As a result, recycling capacities will not be sufficient in the medium term due to a lack of planning security, as companies are reluctant to invest.
- Return logistics are not yet sufficiently developed to cover safe and efficient processes from collection and transport to recycling.
- High-performance batteries are dangerous goods. This applies not only to toxic substances such as fluorine compounds, but also to the existing fire risk. This must be taken into account at every stage of the recycling process and places high demands on storage, transport, handling and recycling itself.
- To date, there are no uniform battery systems. This means that batteries from different manufacturers have different structures. This makes automatic dismantling and efficient recycling more difficult. In addition, the components are difficult to separate, e.g. by gluing or welding the individual cells and the housings.
- The already established processes such as pyrometallurgy offer only a low material recycling rate with a high energy input, therefore a large part of the raw materials (especially base metals and carbon, e.g. lithium or graphite) is lost. In addition, hydrometallurgy uses large quantities of process materials such as chemicals, which have to be disposed of properly once the process has been completed.
There is certainly still a long way to go before a closed-cycle system is established in the Geman and European industry. Nevertheless, there are already promising approaches to how this can be achieved. The researchers of the Fraunhofer Project Group IWKS therefore recommend:
- to always consider the entire material cycle of the batteries and not establish processes independently of one another for individual sub-areas.
- to involve all affected stakeholders, in particular designers, manufacturers, users, recyclers and customers of the recycled product.
- to develop logistics flows with clearly defined processes - from collection to transport and storage.
- to take new approaches to collection and transport concepts. To this end, the collection structure must be improved in cooperation with the manufacturers and economic incentives need to be created. The concepts must be designed in a way that recycling is not made even more difficult. This includes, for example, ensuring that the material flow is as pure as possible.
- to include safety risks during storage and transport directly in recycling concepts and thus to minimize them.
- the further development of alternative, innovative fragmentation and separation technologies such as electrohydraulic fragmentation, in which the active material nickel-manganese-cobalt and the graphite powder are easier to separate from the other components. The aim is to reduce energy and process fluid consumption and to recover as much components of the battery as possible.
- to promote opportunities for automation in the recycling process, including improved labelling of different battery types and manufacturers' commitment to standardization.
- a consistent implementation of a design for recycling, i.e. development and implementation of uniform concepts that take the recycling of batteries and accumulators directly into account during their development (prerequisite for automated recycling processes). To this end, all stakeholders must be involved, i.e. manufacturers, suppliers, automobile manufacturers and recyclers.
- the early transfer of successful recycling concepts to similar products, such as stationary energy storage systems, must be examined.
The researchers of the Project Group IWKS were able to demonstrate in a project that the ideal of directly producing new cells from the material of used batteries can be achieved. This would make it possible to close the material cycle of the most critical components of lithium batteries - provided the necessary infrastructure and framework conditions are established accordingly.
(1) Source, Statista, March 2018, https://de.statista.com/statistik/daten/studie/265995/umfrage/anzahl-der-elektroautos-in-deutschland/ and https://de.statista.com/infografik/9406/elektroauto-ziel-scheint-unerreichbar/
(2) Richa, K. et al : A future perspective on lithium-ion battery waste flows from electric vehicles. In: Resources, Conservation and Recycling, Elsevier, Volume 83, February 2014, Pages 63-76. https://www.sciencedirect.com/science/article/pii/S092134491300253X?via%3Dihub
(3) Hu, Y., Cheng, H, Tao, S.: Retired Electric Vehicle (EV) Batteries: Integrated Waste Management and Research Needs. In: Environmental Science & Technology, 2017, 51 (19), pp 10927-10929. https://pubs.acs.org/doi/full/10.1021/acs.est.7b04207?src=recsys
(4) Source: Ordinance on the Implementation of the Battery Act, §3 Treatment and Recycling, http://www.gesetze-im-internet.de/battgdv/__3.html
(5) Source: DIRECTIVE 2006/66/EC OF THE EUROPEAN PARLIAMENT AND THE COUNCIL OF THE EU of 6 September 2006, https://eur-lex.europa.eu/legal-content/DE/TXT/HTML/?uri=CELEX:32006L0066&from=EN
(6) Source: German Raw Materials Agency, June 2018. https://www.deutsche-rohstoffagentur.de/DERA/DE/Downloads/DERA%202018_cdm_06_Raw Materials Risk Assessment_Cobalt.html