Lithium-ion batteries make portable electronics ubiquitousand they will do the same for electric vehicles. This success story sets the world on its way to generate a multi-million pound of used lithium-ion batteries that can be found in the trash. Batteries are valuable and recyclable, but due to technical, economic and other factors, less than 5% is recycled today. The enormous state of the impending battery situation has led researchers to look for cost-effective, environmentally sustainable strategies to tackle the huge stock of lithium-ion batteries that are on the horizon.
As the popularity of electric vehicles is growing explosively, the same is true of the pile of lithium-ion batteries that once fueled these cars. Analysts predict that by 2020 only China will generate about 500,000 tonnes of used lithium-ion batteries and that by 2030 the global number will reach 2 million metric tons per year.
If current trends in handling these spent batteries stay, most of these batteries can be found in the landfill, although Li-ion batteries can be recycled. These popular power packs contain precious metals and other materials that can be recovered, processed, and reused. Today, however, recycling lasts very little. In Australia, for example, only 2-3% of the lithium-ion batteries are collected and sent to the sea for recycling, according to Naomi Bocal, an environmental scientist at the Australian Organization for Research and Industrial Research (CSIRO). Recycling levels in the European Union and the US – less than 5% – are not much higher.
"There are many reasons why the recycling of lithium-ion batteries is not yet universally established," says Linda L. Gaines of the Argon National Laboratory. A specialist in material and lifecycle analysis, Gaines says the reasons include technical constraints, economic barriers, logistical problems and regulatory gaps.
All these questions feed on a classic problem with chicken and egg. Since the lithium-ion battery does not have a clear path to massive recycling, researchers and battery manufacturers have traditionally been less focused on improving recycling. Instead, they have worked to reduce costs and increase battery life and refill capacity. And since researchers have made only moderate progress, improving recyclability, relatively few lithium-ion batteries are recycled.
Regards: Mitch Jacobi / C & EN
The large, inverted, T-shaped object that fills this case (black) is about 200 pounds of Chevy Volt battery. There is a postcard size battery, 288 of which make up the Volt battery. To scale, the cell phone battery is shown in the center and the iPad battery on the right.
Most of the batteries that are recycled undergo high melting and extraction or melting temperatures, a process similar to that used in the mining industry. These operations, which take place in large commercial outlets – for example in Asia, Europe and Canada – are energy intensive. Plants are also expensive to build and operate, and require complex equipment to treat harmful emissions generated by the melting process. And despite the high costs, these installations do not recover all the valuable materials for the batteries.
So far, most efforts to improve the recycling of lithium-ion batteries have been concentrated in a relatively small number of academic research groups, which usually work independently. But things are starting to change. Led by the enormous amount of lithium-ion batteries consumed shortly by the aging of electric vehicles and ubiquitous portable electronics, startup companies are launching new battery recycling technology. And more scientists have begun studying the issue, expanding the pool of graduate students and newly-appointed post-doctoral students to recycle batteries. In addition, some experts on batteries, manufacturing and recycling have begun to shape large, multilateral cooperation to address the upcoming problem.
In January, for example, Secretary of the US Department of Energy Rick Perry announced the creation of DOE's first Recycle Center for Recycle Li-Ion Batteries. According to Jeffrey S. Spangenberger, ReCell's program director, ReCell's main goals include recycling lithium-ion batteries, competitiveness and cost-effectiveness, and recycling to reduce US dependence on foreign sources of cobalt and other batteries. Launched with an $ 15 million investment and headquartered in the Argon National Laboratory, ReCell includes about 50 researchers based in six national laboratories and universities. The program also includes manufacturers of batteries and automotive equipment, materials suppliers and other industry partners.
At the same time, DOE also launched the $ 5.5 million battery recycling reward. The aim of the program is to encourage entrepreneurs to find innovative solutions for collecting and storing discarded lithium-ion batteries and transporting them to recycling centers, which are the first steps to turn the old batteries into new ones.
Last year, researchers in the UK set up a large consortium dedicated to improving the recycling of lithium-ion batteries, particularly electric vehicles. Led by the University of Birmingham, ReLiB's Recycle and Recycle Recycling Project (ReLiB) collects around 50 scientists and engineers in eight academic institutions and includes 14 industry partners.
Benefits of recycling
140 million: The number of electric vehicles that were expected to be on the road worldwide by 2030
11 million: Metric tons of lithium-ion batteries are expected to reach the end of their service life between 2030 and 2030
30-40%: The percentage of weight of the lithium-ion battery coming from valuable cathode material
<5%: The percentage of lithium-ion batteries that are being recycled at the moment
~ 100%: The percentage of lead in ordinary lead accumulators that are recycled in new batteries
~ $ 70 billion: The market value of lithium-ion batteries is expected in 2022
Sources: International Energy Agency, US Department of Energy.
Battery experts and environmentalists give a long list of reasons for recycling lithium-ion batteries. The recovered materials can be used to produce new batteries, which reduces production costs. At present, these materials account for more than half of the battery costs. In recent years, the prices of the two common metals cathode, cobalt and nickel, the most expensive components, fluctuated significantly. Current market prices for cobalt and nickel are about 27,500 dollars per metric ton and 12,600 dollars per metric ton. In 2018, the price of cobalt exceeded $ 90,000 per metric ton.
In many types of lithium-ion batteries, the concentrations of these metals, along with those of lithium and manganese, exceed concentrations in natural ores, making spent batteries similar to high-enriched ore. If these metals can be recovered from used batteries on a large scale and more economically than from natural ore, the cost of batteries and electric vehicles has to drop.
In addition to the potential economic benefits, recycling can reduce the amount of material falling into the landfill. Cobalt, nickel, manganese and other metals found in batteries can easily escape from the body of buried batteries and pollute soil and groundwater, endangering ecosystems and human health, said Gun Sun, a specialist in pollution control at the Chinese Academy of Sciences science. The same applies to the solution of lithium fluoride salts (LiPF6 in organic solvents used in the electrolyte of the battery.
Batteries can have a negative impact on the environment not only at the end of their lives but long before they are produced. As Gaines notes from Argon, greater recycling means less raw material extraction and less of the associated environmental damage. For example, the extraction of certain metals with batteries requires the treatment of metal sulphide ore which is energy-intensive and emits SOx this can lead to acid rain.
Less reliance on mineral material extraction can also delay the depletion of these raw materials. Gaines and Argonne colleagues explored this issue using computational methods to model how rising battery production can affect the geological reserves of a number of metals by 2050. Recognizing that these predictions are "complex and uncertain", the researchers found that world reserves of lithium and nickel are sufficient to maintain a rapid growth in battery production. But battery production may reduce global cobalt reserves by more than 10%.
There are also political costs and disadvantages that can help recycle lithium-ion batteries. According to a CSIRO report, 50% of the world's cobalt production comes from the Democratic Republic of Congo and is linked to armed conflict, illegal extraction, human rights violations and harmful environmental practices. Battery recycling and cathode formulation with reduced cobalt concentration can help reduce dependence on such problematic foreign sources and increase supply chain security.
Regards: Mitch Jacobi / C & EN
Doheon Kim of the Argon National Laboratory prepares lithium-ion batteries from a pouch to study battery recycling.
Li-ion battery recycling challenges
Just as economic factors can make the case for recycling batteries, they also oppose. Big fluctuations in the prices of raw battery materials, for example, cast uncertainty on the recycling economy. In particular, the recent large drop in the price of cobalt raises the question of whether the recycling of lithium-ion batteries or their re-use is a good business choice compared to the production of new batteries with fresh materials. Generally, if the price of cobalt falls, recycled cobalt would resist competing with the cobalt obtained in terms of price, and the producers would choose picked material over recycled, forcing recyclers to leave the business. Another long-term financial concern for companies considering increasing battery recycling is whether a different type of battery, such as Li air or another vehicle propulsion system, like hydrogen powered fuel cells, will be the basis for the electric vehicle means. market in the coming years, reducing the demand for recyclable lithium-ion batteries.
Battery chemistry also complicates recycling. Since the early 1990s, when Sony sold lithium-ion batteries, researchers have repeatedly adapted the cathode composition to reduce costs and increase charging capacity, longevity, recharging times and other performance parameters.
Some lithium-ion batteries use cathodes made of lithium cobalt oxide (LCO). Others use lithium nickel manganese cobalt oxide (NMC), lithium nickel cobalt alumina, lithium iron phosphate or other materials. And the proportions of components in a cathode type, for example NMC, can vary considerably between manufacturers. The result is that lithium-ion batteries contain "a wide variety of ever-evolving materials, which makes recycling challenging," said Liang An, a battery recycling specialist at the Hong Kong Polytechnic University. It is possible for recycling machines to sort and separate the batteries in order to meet the requirements of people who buy recycled materials, which makes the process more complicated and increases costs.
The battery structure further complicates recycling efforts. Lithium-ion batteries are compact, sophisticated devices, come in different sizes and shapes and are not designed for disassembly. Each cell contains cathode, anode, separator and electrolyte.
Cathodes typically consist of an electrochemically active powder (LCO, NMC, etc.), mixed with carbon black and bonded to an aluminum foil collector with a polymeric compound such as polyvinylidene fluoride (PVDF). Anodes usually contain graphite, PVDF and copper foil. Separators that isolate electrodes to prevent short circuits are thin, porous plastic films, often polyethylene or polypropylene. The electrolyte is usually a LiPF solution6 dissolved in a mixture of ethylene carbonate and dimethyl carbonate. The components are tightly wrapped or stacked and packed securely in a plastic or aluminum housing.
Big batteries that power electric vehicles can contain several thousand cells grouped into modules. Packages also include sensors, safety devices and circuits that control battery performance, all adding a layer of complexity and extra costs for disassembly and recycling.
All these battery components and materials have to be handled by the recycling body to get the precious metals and other materials. In sharp contrast, lead acid batteries are easily disassembled and lead, which accounts for about 60% of the weight of the battery, can be quickly removed from the other components. As a result, nearly 100 percent of the lead in these batteries is recycled in the United States far beyond recycling levels for glass, paper and other materials.
Inside a Li-ion battery
All components of a lithium-ion battery have value and can be recovered and reused. Currently, most recycling plants only recover metals. The circuit diagram describes a cathode material known as NCA made from lithium nickel cobalt alumina.
Regards: Mitch Jacobi / C & EN
Source: National Laboratory in Argon.
Improving recycling methods
Several major pyrometallurgy or melting facilities recycle lithium-ion batteries today. These units, which often move near 1500 ° C, restore cobalt, nickel and copper, but not lithium, aluminum or organic compounds that are incinerated. Facilities are capital-intensive, partly because of the need to treat emissions of toxic fluorine compounds released during melting.
Hydrometallurgical treatment or chemical leaching, which is practiced in China, for example, offers less energy-intensive alternatives and lower capital costs. These processes for the extraction and removal of cathode metals typically occur below 100 ° C and can restore lithium and copper in addition to other transition metals. One of the drawbacks of traditional leaching methods is the need for caustic reagents such as hydrochloric, nitric and sulfuric acid and hydrogen peroxide.
Researchers conducting laboratory tests have identified potential improvements to these recycling methods but only a few companies are conducting pilot plant recycling tests. In the Vancouver area of British Columbia, an American manganese unit converts 1 kg / h of cathode scrap into a precursor that manufacturers can use to synthesize fresh cathode material. The waste relates to dust, such as garnish, garnish and other waste collected in the manufacture of batteries.
Chief Technology Officer Zarko Messeljiya describes scrap as a "low-hanging fruit" – a convenient material to use for experiments before increasing the scale of operations and switching to actually consumed batteries. He explains that the company's process depends on sulfur dioxide for catalysis and does not use hydrochloric acid or hydrogen peroxide.
Ресурсът на батерии в Уорчестър, Масачузетс, управлява пилотен завод, който обработва литиево-йонни батерии със скорост до около 0,5 метрични тона на ден и активно работи за увеличаване на капацитета с фактор 10, според главен изпълнителен директор Ерик Гратц. Много от настоящите методи за рециклиране произвеждат няколко еднометални съединения, които трябва да се комбинират, за да се получи нов катоден материал. Процесът на рециклиране на батерии утаява смес от никелови, манганови и кобалтови хидроксиди. Този катоден прекурсор със смесен метал опростява подготовката на батерията и може да намали производствените разходи.
Междувременно екипът на ReCell на DOE провежда т.нар. Методи за директно рециклиране за възстановяване и повторно използване на батерийните материали без скъпа обработка. Един подход изисква премахване на електролита със свръхкритичен въглероден диоксид, след това смачкване на клетката и отделяне на компонентите физически – например, въз основа на разликите в плътността.
По принцип почти всички компоненти могат да бъдат използвани отново след тази проста обработка. По-специално, тъй като методът не използва киселини или други тежки реагенти, морфологията и кристалната структура на катодните материали остават непокътнати и материалите запазват електрохимичните свойства, които ги правят ценни. Гейнс казва, че е необходима още работа, за да се приложи този икономичен подход.
С уважение към: Алиреза Растегарпанах и Рустам Столкин / Екстремна лаборатория по роботика
В университета в Бирмингам членът на екипа на ReLib Алиреза Растегарпана разработва роботизирани методи за безопасна, автоматизирана обработка на изразходвани литиево-йонни батерии.
В проекта ReLiB на университета в Бирмингам главният изследовател Пол Андерсън казва, че екипът вижда ясна възможност за повишаване на икономическата ефективност на рециклирането на батериите чрез автоматизация. За тази цел екипът разработва роботизирани процедури за сортиране, разглобяване и възстановяване на ценни материали от литиево-йонни батерии. Алън Уолтън от Бирмингам, коинвеститор, добавя, че използването на роботизирани устройства за разглобяване на батерии може да елиминира риска от електрически и химически наранявания на работниците. Автоматизацията може да доведе и до по-голямо отделяне на компонентите на батерията, повишавайки тяхната чистота и стойност, казва той.
Въпреки че повечето от тези стратегии остават на ранен етап на развитие, необходимостта от тях се увеличава. Понастоящем броят на батериите с излезли от употреба електрически превозни средства е нисък, но скоро ще скочи. Многобройни пречки са на пътя на широкомащабното рециклиране, но „възможностите винаги съществуват заедно с предизвикателствата“, казва An of Hong Kong Polytechnic. Време е да вземем бика от рогата и да се заемем сериозно с рециклирането на литиево-йонни батерии.
Химически и инженерни новини
Copyright © 2019 Американско химическо общество