Is the tried and trusted lead-acid infrastructure the way forward for recycling lithium-ion EV batteries? In this special feature article, technical editor Dr Mike McDonagh looks at the challenges facing the commercial reuse of LIBs.
Lithium-ion chemistries are increasingly under the R&D microscope as demand for the use of electric vehicles steps up a gear worldwide. But the rush to manufacture lithium-ion batteries (LIBs) without a commercial recycling process being in place— an issue covered in the summer edition of BEST— means LIB-makers are heading for an impending crisis.
We all have to make a concerted and co-ordinated effort to utilise the existing knowledge and know-how of companies already in the business and those that are emerging to resolve the outstanding technical and commercial issues standing in the way of the wholesale recycling of lithium-ion batteries.
With growing pressure from current and future demands for the electric vehicles market, lithium-ion chemistry is the only commercially available technology that can provide the required energy density for this application. Unfortunately, with massive global investments being made to meet spiralling demand, far less attention is being given to the fundamental question of how these batteries can be commercially recycled.
The obvious answer is to ensure that all materials and designs currently being used for electrochemical energy storage devices (batteries) are fully recyclable. Easy to say but not so easy to implement. The current focus for EV battery design is to increase the energy density in order to bring down the kWh cell price and increase the driving range. This has meant use of complex mixtures of materials, often in low concentrations within the battery, making recycling more difficult and commercially unattractive. In order to have an effective recycling programme there are some fundamental requirements:
- An established infrastructure of collection, sorting, safe storage and safe transport that can handle the volumes and comply with legislation.
- Recycling processes that are environmentally sound and can separate the constituents to be reused for battery manufacture at an economic cost that is commercially viable.
The aim of this article is not only to highlight the shortcomings of the present situation for non-lead industrial batteries, but also to show that the lead-acid model is a rational way forward. It will also highlight that the present lead-acid recycling infrastructure is already processing large lithium-ion and nickel-based batteries. The companies already processing lithium-ion and nickel batteries have had to find solutions for the significant costs of collection, storage and transport of these hazardous wastes and could certainly be part of finding a solution to commercialising the recycling of lithium-ion EV batteries.
There are some misconceptions about LIB recycling that need putting to rest. One is that using old lithium-ion batteries in a lower capacity use is a form of recycling. This oft-quoted example of recycling is really nothing of the sort: if anything it is ‘extended use’. Otherwise, we could classify the selling of used cars at a lower price as ‘recycling the vehicle’. For our purposes, we are looking at the cells rather than the supporting architecture of electronics, connectors and containers as the primary feed for recycling. It is these components that are the feedstock and resource for the increasing volumes of batteries we will need to manufacture for EVs and storage. And should the battery technology or chemistry change, they could then become the future toxic waste piles that we need to deal with.
Looking at recycling principles, there are basically two recycling routes: closed loop and open loop Fig 1. The former returns spent goods to be processed and their constituents to be reused in their original purpose with no restrictions on the number of recycling events. The latter generally has one further use in a totally different application eg, rubble for motorway foundations or incineration for energy supply.
With these principles in mind, this article examines the current commercial and technical status of battery recycling for the battery chemistries that dominate the industrial and consumer secondary battery markets. These are:
Lead-acid – PbA
Lithium-ion – LiB
Nickel Cadmium – NiCd
Nickel Metal Hydride – NiMH
Fig 2 shows the relative proportions of each battery chemistry sold in 2016.
Whilst lithium-ion has the highest sales value, PbA is still the largest proportion by kWh of battery chemistries being sold. LIB however, is rapidly increasing its market share and if the EV ambitions currently being promoted by various countries’ governments are realised, then it won’t be long before the issues of dealing with spent LIBs will be firmly sitting on our doorstep. For this reason, this article will give a higher proportion of attention to the current issues for recycling this technology compared to the other chemistries and their well-established recovery routes.
Looking first at the largest amount to recycle, which is the PbA sector, the picture is one of a virtual 100% recovery rate of all the components. There are advances in this sector that will be briefly mentioned, however, the technology used for the recovery of lead from these batteries invariably involves pyrometallurgy. The other components, namely plastic and acid, are recovered and recycled. There are new processes being investigated for recovery of acid, and also hydrometallurgical recovery of the leady paste from the plates is close to being a commercial reality. That lead-acid batteries are the most successfully recycled product on our planet is impressive (Fig 3).
Equally impressive is the existing infrastructure that collects, stores and then delivers battery scrap to the recyclers, who then sell on the separated and reprocessed products to the relevant manufacturers. This is a classic and ideal closed loop system. It is this framework that enables lead batteries to be the recycling success story they are.
Since the established and new PbA processes have been extensively covered in the previous two editions of BEST, I will give only a brief overview of the technical and commercial aspects of this industry. Table 1 lists the normal and new commercial processes (pyrometallurgical) and the developing, not yet commercial processes, which at this stage are hydrometallurgical.
Without exception, all processes rely on the collection, storage and transport of spent batteries for their feedstock. This means that here is a well-established, highly-regulated infrastructure that, because of EU border regulations— (EC) No 1013/2006— generally operates at a national rather than international level In Europe. To understand how this part of the recycling process works, I spoke to a leading European recycling company and member of Eurobat. G&P Batteries is the biggest collector and along with their sister company, HJ Enthoven, is also the biggest battery recycler in the UK.
G&P have been operating for 40 years and have a proven infrastructure for recycling lead-acid batteries. With the exception of alkaline cells this infrastructure extends to other chemistries. For NiCd there are limited collection facilities in the UK and all material is exported to Europe for processing. The same situation holds for NiMH battery recycling. Regarding lithium-ion, their commercial director Tom Seward is very clear:
“There are only a limited number of true lithium-ion recyclers worldwide and none in the UK. All UK material is exported, predominantly to Europe. EU member states (which still includes the UK) have an obligation to recycle 45% of all batteries sold. Britain fell short of this by just 1% in 2017, but this figure has a heavy reliance on lead-acid’s near 100% record.”
According to Greg Clemenson, the MD of G&P: “Whilst it appears that the UK has missed its recycling target by less than 1%, the reality is that this country is clearly underperforming when it comes to waste battery collection and is side-stepping its obligations by apparently fudging the figures… the government’s figures clearly show that lead-acid battery collection continues to dominate, whilst the other chemistries, which the (EU) directive was intended to address, have actually dropped by 3% since 2016.”
The PbA recycling processes are still the mainstay of the recycling industry, but it is the infrastructure of collection, transport and segregation that is the real success story. It is this well-established structure, with dedicated collection zones and safe containment, highly regulated transport and established segregation methods, that do (and will ultimately) benefit the entire battery industries of all chemistries. Many companies globally are becoming more alert to the growing problem of lithium-ion batteries ending up in the lead-acid recycling stream. Uniseg in Australia, for example, which specialises in collection and transport of lead-acid scrap batteries, is now developing its own LIB container.
However, it is not without its problems. Due to the increasing number of lithium-ion substitutes for PbA entering the marketplace, it is becoming increasingly difficult to identify and separate out the potentially dangerous LIB equivalent (Fig 4). The consequences of a single LIB being incorrectly identified can be highly dangerous. A damaged LIB finding its way to a battery breaking plant (Fig 5) could cause serious damage to the equipment and serious harm to plant operators.
Again G&P has direct experience of these problems and suffered a serious fire in 2014. This was successfully contained, but firefighters had to be called to safely extinguish the blaze. G&P invest heavily in training their employees to identify and deal with the different battery chemistries. However, the risks are still there and not going away. According to G&P commercial director Tom Seward: “The biggest risk we see (for collecting and sorting scrap lithium-ion batteries) is knowledge and identification. A number of lithium-ion battery manufacturers are marketing it as ‘safe’. Yes, they are safe, but only when the risks are known and managed— these are not known by the marketplace, so they are then ‘unsafe’!”
Whilst these are concerning public safety issues, they can be overcome. The other area of concern is the commercial viability of recycling. With less than 30% of LIBs currently recycled what are the financial incentives to consumers and potential recyclers? This was partly covered in the summer edition of BEST, but G&P can shed some light on the situation from their own business activities. The majority of lithium-ion batteries sold on the UK market today have a recycling charge.
The recycling of other battery chemistries, at least for the present and for the foreseeable future, has a heavy dependency on the infrastructure for lead-acid battery scrap. Nickel-based batteries and LIBs also benefit from this. Nickel batteries do have an established recycling route, but a large portion, particularly from portable hand tools, are disposed of in the same collection centres as PbA batteries. However, they do not have a positive scrap value as with lead-acid. The cost of collection, transporting and segregation is a substantial part of the metal recovery costs. This often results in a collection or processing charge that is either borne by the customer or the collection site, which subsidises this cost from the PbA scrap revenue.
Another problem here is the current lack of legislation or even guidelines that may apply to collection, storage and transport of lithium-ion battery scrap. This is a problem well understood by the UK battery company Cawleys, which operates a collection, segregation, dismantling and transport service dealing with the growing problem of spent LIBs. Alan Colledge, the firm’s senior manager for hazardous services said:
“When Cawleys were initially asked to look at lithium battery disposal back in 2012 we discovered that the facility to treat, dismantle and recycle this type of battery in the UK simply did not exist. Unfortunately, six years later the situation remains the same. However, with the rising popularity of electric vehicles (and the batteries needed to power them), we recognised that there was a pressing need to focus on the future sustainability of these products.”
As a result of their research, Cawleys was able to identify suitable collection, storage and transport resources to meet existing requirements. This included appropriate licensing and equipment to cope with the hazards of dealing with used LIBs and also finding suitable recycling companies. The next step was to develop a working relationship with these companies and also to develop a licensed facility and transport equipment capable of storing and shipping lithium-ion waste. Fig 6 shows a container designed to handle waste LIBs. It has to prevent impact damage, movement of the batteries during transport and be able to contain a fire and the toxic gases that can be released from damaged or overheated cells. The current situation for lithium-ion recycling is neatly summed up by Colledge:
“Many universities are currently undertaking research on further options in relation to (lithium-ion) treatment and technologies that are likely to provide advanced solutions in the future. However, the demand exists here and now, and it is vital that we tackle it head on. At Cawleys, we believe that we are moving in the right direction to achieve this, but the industry needs to move fast to provide solutions.”
In the UK at least, the current focus on recycling lithium-ion by the BEIS is welcome, but the problem is that the technical goalposts are moving. The valuable components, such as cobalt, are reducing in concentration and there is a danger that what is developed over the next five years may not be applicable to the market at that time. The current recycling methods for LIBs will be discussed later in this article.
The recycling of lead-acid is of course another story, utilising as it does established and profitable processes in existence worldwide. Apart from the collection and sorting procedures already mentioned, the process of battery pre-treatment before recovery is universally adopted for all recycling methods. The current commercial process for PbA batteries is pyrometallurgical, Fig 7 is a schematic of the general process.
The starting point is battery breaking and segregation. This consists of collecting battery scrap then feeding it into breakers, often a jaw crusher to crack the plastic boxes and release the acid and internal components. This is followed by ball milling, water classification and washing to separate the lead alloy, lead paste and plastics. Fig 5 shows the feed into a breaking mill. The paste material is pumped and collected in a filter press to remove at least 95% of the moisture before going to the blast or reverberatory furnace for reduction to lead (Fig 8). This lead is then used as feedstock in kettles along with the metal alloy separated in the breaker to make refined lead or alloys. This is well established and has been covered in previous issues of BEST, so will not be gone into in any depth in this article.
However, there is one point that should be mentioned and that is the slag by-product from this process. It is contaminated with small quantities of lead and as such cannot be used in landfill as with say ferrous slag, because of the possibility of leaching lead into the ecosystem. This is minimised by careful control of the refining parameters of furnace atmosphere, temperature and slag chemistry. Gopher Resource, based in Eagan Minnesota, is a good example of a recycling company that has managed to minimise its slag waste.
The company is a lead-acid battery recycler that processes around 1400 tonnes of lead-acid batteries per day (Fig 9). Their products are refined lead; lead alloys and recycled polypropylene pellets, which are sold back to lead-acid battery manufacturers. As the largest battery recycler in the US, they have an extensive collection, storage and transport structure for scrap batteries. This means they have to deal with every battery chemistry they receive, including lithium-ion and nickel metal.
These are collected at their collection centres, manually sorted and removed from the PbA scrap, then packaged and sent to the relevant recycling companies. Unlike PbA scrap, there is a cost for these battery types that is billed back to the customer where possible. As lithium-ion does not have a resale value, this type of scrap does add to the cost of their operation. They also have the problem of identifying the different battery types, particularly distinguishing the lithium-ion PbA substitutes now entering the recycling stream. To avoid the disaster of furnace explosions from these batteries staff need additional training and additional time during the sorting process. Gopher also have local programmes to educate the public on identification of battery scrap. This is administered as part of their community service programmes, which include:
Operation of the Recycling Zone in Dakota County, Minnesota. Opened in 1993, this facility provides recycling and household hazardous waste collection— most at no charge— for surrounding residents and small business. In 2017, the Recycling Zone collected nearly 1800 tonnes of hazardous waste, of which 816 tonnes were electronics. The facility also collected more than 680 tonnes of steel, plastics, glass and paper recyclables. In addition, it has helped facilitate the reuse of more than 136 tonnes of oil and latex-based paint, cleaning supplies and other materials.
Sponsoring of the Eagan Foundation— which in 2018 donated $138,000 to 124 scholarships from various financial, academic, cultural and athletic backgrounds.
Clearly, the benefits of lead recycling by responsible companies like Gopher, are far more wide-reaching than the commercial interests of the companies operating in this arena.
Outside of the conventional pyrometallurgical routes, there are new developments in hydrometallurgical processes that treat the paste material fraction from the breaking process with acetic acid to produce lead citrate. Smelting this back to lead produces 75% less slag and uses considerably less energy than the conventional smelting process. The UK company Aurelius has developed this process to a near commercial status (as reported in BEST spring 2018) and are working with international partners to develop a comprehensive recycling programme to include the battery acid, and novel ways of producing the leady oxide feedstock for battery paste.
Outside of the existing lead-acid infrastructure, there is the Rechargeable Battery Recycling Corporation (RBRC), which was founded in 1994 in the US to encourage the recycling of rechargeable batteries in North America. RBRC is a non-profit organisation, which collects batteries from consumers and businesses and sends them to recycling companies such as Inmetco and Retriev in North America. These companies have been operating for many years and typically process nickel and lithium-based chemistries. Sony and Sumitomo Metal in Japan have formulated a technology to recycle cobalt and other precious metals from spent lithium-ion batteries.
In all cases, it is necessary to separate the batteries prior to arriving at the recycling plant on the basis of their chemistries. For nickel-based batteries, NiCd and NiMH are segregated then placed in assigned boxes at the collection point. According to battery recyclers, if a steady stream of batteries, sorted by chemistry, were delivered at no cost to the recycling facility, then recycling of nickel-based batteries would be a profitable business. However, preparation and transportation are significant financial additions that have to be passed on to the consumer as a processing charge.
Once received at the plant (Fig 10 is a schematic representation), the recycling process begins by removing the combustible material, like plastics and insulation, with a gas fired thermal oxidiser. Gases from the thermal oxidiser are directed to the plant’s scrubber where they are neutralised to remove pollutants. The methods leave the basic cells that contain the metal. The cells are chopped into small pieces then heated until the metal liquifies. Non-metallic substances are burned off; that leaves a black slag that is removed with a slag paddle. The different alloys naturally segregate by density and are separately skimmed off using a rotating arm. Cadmium will vapourise at high temperature; the vapour produced on heating is blown into a water-cooled condensing tube. This resulting condensate is 99.95% pure cadmium.
Nickel is recovered from NiMH batteries by mechanically separating the individual materials (plastic, hydrogen and nickel) within a vacuum chamber to prevent the hydrogen escape. The yield of this process is a product with high nickel content that can be used in the production of stainless steel.
There is sometimes an intermediate stage where a recycler does not separate the metals on site, but instead pours the mixed liquid metals directly into moulds to produce 30kg ingots or the larger one-tonne castings. They are then sent to metal recovery facilities. Here, the material is used to generate nickel, chromium and iron re-melt alloy for the production of stainless steel and other high-end products.
Current nickel-based battery recycling processes require a high amount of energy. It takes 6-10 times the amount of energy to reclaim these metals from recycled batteries than from other sources. Different countries impose their own rules and regulations in making recycling feasible. In North America some recyclers bill on weight. Their rates vary according to chemistry. Battery types which yield high metal retrieval rates are priced lower than those that yield less valuable metals. Nickel-metal-hydride batteries produce the best return. It generates sufficient nickel to pay for the process. The highest recycling fees apply to nickel-cadmium and lithium-ion batteries because demand for cadmium is low and lithium-ion contains little retrievable metal.
The fact that LIB recycling is uneconomic is a major cause for concern. We are in a position where EV sales are increasing as more incentives to purchase the more expensive and less versatile vehicles are given. According to one US media report, EV ownership “will balloon to about 125 million by 2030, spurred by policies that encourage drivers, fleets and municipalities to purchase clean-running cars”.
This is borne out by the statistical predictions of Bloomberg for the cost of EV battery packs Fig 11. However, as usual these estimates are flawed because they do not refer to the battery pack cost but rather the kWh cost of the battery pack. Since a major requirement for EV sales adoption is to increase the vehicle range, it is more likely that the battery packs will remain at the same price but with a higher energy storage capability to increase the vehicle range between charging points. Currently, the battery is about 50% of the EV price. The likelihood is that it will remain so, with the battery pack staying about the same physical size and weight but providing an increased range due to the higher energy density.
Turning to the recycling of spent lithium-ion packs, we need to understand the existing infrastructure for its collection, storage and transport. Having interviewed companies in the UK and US, a fairly encouraging picture emerges of companies already with an established infrastructure for PbA batteries adapting to the very different requirements of lithium-ion chemistry.
In a similar vein, there are companies who recycle lithium-ion batteries by re-using old batteries in a lower grade application. This is known as second use and is not, strictly speaking, recycling. This is possible with LIBs as they still function at lower capacity once their performance has degraded to the point where they cannot meet the demands of the first-use application. One company that claims to operate profitably in this market is Aceleron. Operating from the UK, the company has a patented method of containing and joining used lithium-ion battery cells that is cheaper than the conventional connection and welding methods.
Aceleron’s process starts (as does most lithium-ion recycling) with manual segregation of types followed by dismantling then sorting of the components into various categories. The general initial breakdown would be as shown in Table 2.
They have added the step of recycling the separated cells into new batteries. This is the second use as discussed above. That’s not new, but their patented method of packing the cells and using compression to make contact between them is very novel if not controversial. Fig 12 shows their container and a typical lithium-ion battery arrangement. They also use the electronic components of the dismantled batteries as well as the cells to make new battery packs.
Of course, second use could be regarded as a stopgap measure, but it does at least extend the life of the battery. This will reduce the immediate burden of disposal or recycling of at least part of the future scrap battery mountain. Once again, the necessity to dismantle and segregate is a labour intensive and expensive step. Aceleron claim that the removal of the connector material and welding process can make this recycling route profitable. According to the firm’s CEO Kevin Simmons:
“The battery components are chosen by type and performance and then put into packs and connected by pressure with patented technology. The method does not allow initial contact to preserve the integrity of the pressure relief valve and ensure even spacing thus even pressure when contacted. This is necessary to provide a cost-effective solution without the expense of connecting bars such as nickel or nickel coated steel/copper plus the welding process.”
Once again, the process of collection, storage, separation, and in this case the added burden of classifying and sorting the components into performance bands of A to E, all adds to the cost. Aceleron claim that the removal of the intercell connecting strip of nickel or metal plated with nickel actually makes this process profitable.
What is quite clear is that to economically recycle lithium‑ion batteries in a closed loop system, ie returning all the components to their original form to reuse, is not yet commercially established for all LIB chemistries. It has been predicted by some authors that unless there is a viable and economic process to achieve this in the very near future, then the global EV programme could seriously stall within the next 10 years. Whilst there are companies that can collect, transport and process waste lithium-ion batteries, and some commercial success is possible for second use batteries, the prospect of closed loop recycling to commercially provide feedstock for new batteries is as yet unrealised. In general, the flow for LIB recycling is shown in Fig 13.
There are pyrometallurgical processes as typified by Umicore, Retriev and Glencore that have been clearly defined and are capable of recovering expensive cathode materials such as cobalt as well as lithium for the feedstock required for making new batteries. However, what is not certain is the commercial viability of the processes. Estimates of the cost of recycled cobalt, for example, range from two to five times that of the mined primary material. But there is potentially good news in the fact that the concentration of these elements is far higher in the batteries than in the ores from which they are extracted (Table 3).
The viability of these recycling processes depends on three main parameters:
- The quantity of scrap feedstock available to provide economy of scale.
- The cost of collection, transport, segregation and extraction of the materials.
- The price of virgin materials used for battery manufacture.
The recycling of lithium-ion batteries is complicated. By necessity, there are components included in the total battery pack that do not contribute to energy storage. These are essentially the container, the BMS (battery management system), the connecting bars or strip, the intercell current control electronics (mosfets, IGBTs), cooling system and possibly fire safety equipment. All of these components are hand sorted before the lithium-ion cells are extracted for further processing. There is a value chain here where these sub components may be recycled, perhaps economically.
The real prize, however, is the recovery of the cathode materials, which are the main elements that determine the capacity and performance of the battery. Table 4 lists the current cathode types and their constituent materials. The metals forming the cathode, which is essentially a carrier for the Li+ ions, are mostly found in period four of the transition metals. These are nickel, cobalt, vanadium, iron and manganese. The pyro and hydrometallurgical extraction of these elements from the cathode materials is a long-winded process (Fig 13).
Taking a broad overview, there are two approaches: pyro and hydro metallurgical processes.
In general, for high temperature operations (Fig 14), after dismantling the lithium-ion batteries to the module level, they are fed to a high-temperature shaft furnace with a slag-forming agent that typically includes limestone, sand, and slag. The electrolyte and plastics burn to supply some of the energy for the smelting, and valuable metals are reduced to an alloy of copper, cobalt, nickel, and iron, which are then recovered by leaching. The resulting slag contains lithium, aluminium, silicon, calcium, iron, and any manganese that was present in the cathode material. Recycling aluminium or lithium from the slag is not economical or energy efficient and gas clean-up steps are necessary to avoid the release of potentially toxic by-products. This process depends on having cobalt or nickel in the cathode to be economically viable. Designs with manganese spinel or LFP cathodes would not provide sufficient after-sales revenue.
There are liquid extraction processes classified as hydrometallurgy, solvent extraction, precipitation and leaching (Fig. 15). Looking briefly at each of these methods, the most significant of these currently is the hydrometallurgical route. With this, the component metals react with an aqueous solution to form a water-soluble salt. Subsequent processes such as electrolysis, cementation, crystallisation or precipitation can yield high purity compounds or the reduced metal. The advantages are low energy use, low temperatures of operation, easy targeting of material to recover and low air pollution levels. The disadvantages are the low throughput times (slow processes) and the potential for high effluent levels and possible water pollution.
Solvent extraction relies on metallic ions in the aqueous phase being immiscible in organic solvents. Use of complexing agents can separate out metal compounds of only slightly differing miscibility very effectively. Precipitation of metallic compounds by altering pH or reacting with other solutions to create insoluble metal compounds is fairly standard chemistry. By selecting the final compound chemistry, the washed precipitates can be sold as intermediate products in the lithium-ion battery materials supply chain. Leaching using acids or even microbes is a common method of metal extraction from ores or slags. The disadvantages are the slow recovery times for economic viability and the potential for water pollution.
The economic case for either of these approaches is yet to be proven. Bearing in mind the previously mentioned three parameters to determine commercial viability, we have yet to see significant numbers of large pouch design EV batteries arriving in the recycling stream. The price of the component materials is a large factor in the economics of recycling, and both lithium and cobalt have been increasing over the past five years. However, the catch-22 mentioned in the last edition of BEST’s MythBusters article, means that higher prices for component materials is a good driver for recycling: it will reduce sales of batteries and therefore feedstock for future recycling and recovery of component materials.
The other factor of availability is the life of the product. The shorter the life the sooner the material is available as feedstock. Current projections, based largely on crystal ball gazing, give an optimistic 10‑year life for EV batteries. My own experience, based on knowledge of a local taxi company in my town, is more like three to five years. Again, this could be good news for recyclers looking for volume but bad for sales of EVs and therefore future volumes of recyclable scrap. Once again, catch-22.
Another approach is to say “Why bother with this separation step?” As it is difficult and expensive to separate all these materials, why not simply re-use the cathode in new batteries? The performance of a lithium-ion cell deteriorates predominantly due to two factors: the loss of mobile lithium ions in the electrolyte and the gradual coating of the anode by lithium metal. Professor Zheng Chen of UC San Diego University also claims to fully recover the cathodes of spent LCO and NMC lithium-ion cells after separation from the battery. The method involves first collecting cathode particles from spent lithium‑ion batteries. Researchers then pressurise the cathode particles in a hot, alkaline, solution containing lithium salt. This solution can be recycled and reused to process more batches. Afterwards, the particles go through a short annealing process in which they are heated to 800°C and then cooled very slowly. The cathode’s atomic structure also changes such that it’s less capable of moving ions in and out. The recycling process that Chen’s group developed restores both the cathode’s lithium concentration and atomic structure back to their original states. (Green Chemistry 2018)
In summary, it seems that there is a recognition that lithium-ion batteries will need to have a commercial recycling solution. Much of the focus of R&D is on the process of recovering the cathode materials in order to ensure a supply for future EV battery sales. This is an important consideration and combined with the existing industries working in this area it is hoped that a commercial solution for all of the various lithium chemistries and concentrations of recoverable transition metals of the cathode will be found in the near future. When the low concentration of the diverse mixture of metals in a LIB are compared with a single metal content of at least 60% in most lead batteries, it is all to clear that a total closed loop, commercial recycling process for lithium-ion batteries is a very challenging endeavour.
It is difficult to assess the economic status of the various recycling processes at present, as this is a commercially sensitive area. However, it is dependent on the costs of the process including: the recycling infrastructure, the commodity price of mined raw materials and any charges imposed on the consumer.
Perhaps the biggest catch-22 of all is that provided by nature. Lead is a relatively inert material with low energy bonds created in its chemical and electrochemical reactions. This means less energy is stored and released by lead-acid batteries than by more reactive elements like lithium. However, it also means that the energy required to reduce and refine lead is a lot less than more electrochemically active metals. Add to this its low melting point and we see why for millennia lead has been the most recycled metal in human history. For lithium-ion batteries to be recycled cost effectively, we may need to accept that their effective properties that drive EVs will also drive higher recycling costs. The stakes are high, the challenges equally high. We have to make a concerted and co-ordinated effort to utilise the existing knowledge and know-how of companies already in the business and those that are emerging to resolve the outstanding issues both technical and commercial, which are preventing wholesale recycling of lithium-ion batteries.