Recycling analysis – Options for lithium batteries
In a recent research study at ANU, Matthew Doolan and Anna Boyden considered the full life cycle of lithium ion batteries and their recycling options to assess environmental pluses and minuses. They present a summary here.
Battery use in consumer electronics is growing rapidly, with an ever-increasing range of battery-powered products, from mobile phones to laptops to power tools, and battery use in electric vehicles and home power systems adding to the equation. Many of these products now use lithium ion batteries, with such use expected to double over the next six years1 and then continue to grow: a recent report projects a 41-fold increase in lithium ion battery waste in Australia by 2036, from 3340 tonnes in 2016 to 137,000 tonnes in 2036.2
This growing use of batteries comes at a cost to the environment, including impacts from mining of the materials used in the batteries and end-of-life disposal issues. When it comes to end-of-life, lithium ion batteries contain relatively low levels of toxic materials, compared to batteries containing lead and cadmium, and therefore in many countries, including Australia, they can be legally disposed of in landfill.
However, there are environmental and safety risks. Helen Lewis from the Australian Battery Recycling Initiative (ABRI) notes that used lithium ion batteries need to be carefully managed during transport and disposal as they can explode or catch fire if they get damaged or over-heated. There have already been some incidents in the waste industry that were attributed to lithium batteries. These risks can be managed in a properly run recycling process.
In 2012–13 in Australia it’s estimated that 98% of lithium ion batteries were sent to landfill1, with many batteries also hoarded at home in old mobile phones. Recent initiatives have been set up to initiate collection and potential recycling or reuse via MobileMuster and ABRI, and the effectiveness of these is still to be assessed.
In addition to reducing landfill impacts, recycling of lithium ion batteries has direct environmental benefits including reducing the impacts of producing batteries from new materials—potential benefits include material recovery, less impact from mining, reduced emissions and reduced energy consumption.
Recent developments in battery technology to reduce the cost of batteries have meant a decrease in the amount of valuable material in lithium ion batteries (specifically cobalt and copper), thus reducing the financial incentive to recycle lithium ion batteries, hence regulation is needed.
It’s important to assess the most effective approach to recycling lithium ion batteries. Choosing the wrong approach could actually increase the environmental impact of dealing with the batteries at the end of their life.
There are three commercially available recycling techniques used for recycling lithium ion batteries: mechanical, pyrometallurgical and hydrometallurgical. Each process recovers different materials and amounts of energy from the battery being recycled.
Mechanical processes involve ‘liberating’ components and materials from the battery and then sorting these materials. Liberation of components and materials can be done by crushing or shredding the batteries. The materials resulting from this process can then be separated according to their physical properties such as weight (using flotation on a series of liquids) and magnetic behaviour (using strong magnets). These processes are effective at capturing most of the materials within the lithium ion battery, but cross-contamination can reduce efficiency.
Pyrometallurgical processes such as smelting, pyrolysis and refining involve the use of high temperatures to recover materials. These processes are unable to recover organic materials such as plastics, but they can recover the embodied energy of some of these materials in the smelting process.
Finally, hydrometallurgical processes use chemical reactions to extract the raw materials. These processes dissolve materials that have passed through a mechanical crushing process. These solutions are then purified to precipitate (thus solidfying) the desired material. Again, these processes are unable to recover organic materials but they do result in high purity recovered materials.
With input from ABRI and MobileMuster, we conducted a survey of actual facilities doing the recycling to assess the environmental impact of the process used, the materials recovered and the impact of transporting the material to the recycling facility.
Of the recycling facilities surveyed, mechanical processes recovered the most materials from the battery, with an average of seven of the possible 10 materials being recovered. Hydrometallurgical processing ranked second, recovering on average six materials, while pyrometallurgical processes only recovered five of the materials.
Interestingly, only one of the recyclers surveyed recovered lithium from the batteries (perhaps partly because lithium comprises less than 5% of the weight of a lithium ion battery). Only copper and cobalt were recovered by all recyclers, which is likely due to the value of these materials.
The efficiency of the material recovery for each process (the percentage of materials recovered) was calculated from information provided by the facility. This efficiency varied from 31% for a pyrometallurgical process to 70% for a mechanical process.
The global warming potential, human toxicity potential and terrestrial toxicity was assessed for both the hydrometallurgical and pyrometallurgical processes. Due to a lack of information, the mechanical process impact was not assessed. Mechanical processes vary significantly from country to country. In Europe it’s an automated process but in parts of Asia it’s still largely manual. The main advantage of this process is that the materials are recovered at a high efficiency and there is little residue produced. The other processes produce chemical and gaseous waste that are not easily dealt with.
The hydrometallurgical and pyrometallurgical assessments showed that both processes impact global warming more than landfill due to increased energy use in recycling and transport. However, both processes result in significantly lower impacts on human health and terrestrial toxicity than produced by landfill.
As at 2014 Australia did not have a local lithium ion battery recycling facility, so our study looked at the impacts of transporting discarded batteries to other countries for processing. [Ed note: in 2015 Melbourne-based PF Metals began local recycling of lithium ion batteries, a welcome initiative.] Battery recycling facilities exist in Asia, Europe and the USA. Shipping can have a significant impact on the environmental benefits of recycling lithium ion batteries. For example, when the environmental impact of shipping is considered, the global warming potential increases by up to 20% for shipping to Europe, and the impact on human toxicity sees a 400% increase, due to the pollutants from fuel emissions.
This assessment concluded that the most effective approach to recycling lithium ion batteries for Australia is to use mechanical processes, while minimising the shipping distance. The effectiveness of the mechanical recycling process is largely due to the recovery of plastic, which is not recovered in any of the other processes.
This study was conducted in the context of the current use of lithium ion batteries in small consumer products. However, there are a growing number of products using larger batteries, such as for home power storage or electric vehicles. As these uses become more popular there will be a growing local demand for processing this waste stream, adding to the already strong demand for battery recycling options from consumers (for example, in 2014 Planet Ark’s RecyclingNearYou website received more than 117,000 queries from the public looking to recycle batteries). Larger batteries are also less likely to be hoarded or sent to landfill, creating more of a demand for recycling and reuse options.
1 K O’Farrell, R Veit and D A’Vard, ‘Trend analysis and market assessment report’, National Environment Protection Council Service Corporation, July 2014.
2 Paul Randell, Waste lithium-ion battery projections, July 2016, www.bit.ly/2bXxU7J