The entire battery recycling process chain begins with the collection. The EU Battery Directive ensures that it is mandatory to provide free collection of industrial and automotive batteries.

Meanwhile, the EU's End-of-Life (EoL) Vehicle Directive regulates the collection of EoL lithium-ion batteries from EVs, where the manufacturers or OEMs must take back waste batteries. A contract with third parties such as recycling companies or car workshops is permitted.

In general, there are three methods of recycling processes to recover and regenerate spent lithium-ion batteries: Pyrometallurgy, hydrometallurgy, and direct recycling.

Lithium-ion battery recycling methods. Credit: DIGITIMES Asia

Notes. Li = Lithium, Co = Cobalt, Ni = Nickel, Mn = Manganese, Al = Aluminum, Cu = Copper, C = Graphite, Si = Silicon. Source: Shekhar, A. K. et al. (2022, p. 4).

Pyrometallurgy and hydrometallurgy methods both recover valuable metals and salts in commercial applications. The direct recycling process, on the other hand, only recovers electrode materials (especially cathode materials) at small scales. The pre-treatment phase remains common in the above-mentioned categories.

Pre-treatment process is necessary to dismantle safely, recover the valuable organic components expediently, separate the active substances efficiently, as well as reduce impurities and facilitate the subsequent recovery process.

There are many different chemistries and designs in use today that pose recycling challenges. Not every cell chemistry can be recycled at any recycling route. Thereby, many recyclers are specialized in particular battery chemistries because of the complicated sorting process necessary for reliable recycling.

To deal with them effectively, many spent lithium-ion batteries need to be sorted by specialized technicians, followed by being disassembled (machine). This brings up the handling cost.

By 2060, the planned amendment of the EU Battery Directive intends to provide a so-called battery passport. It will be mandatory to accompany certain batteries with a data structure that is accessible online and linked to the physical battery via a QR code.

The battery passport will contain information including capacity, lifetime, and presence of hazardous substances. This will make it easier to identify spent lithium-ion batteries' materials and consider appropriate recycling methods before they are disposed of.

Common separating processes range from visual sorting followed by hand picking to magnetic separation, X-ray, electromagnetic, and UV-based sorting.

After sorting, EV battery packs must be disassembled. Disassembling lithium-ion batteries allow recyclers to get a certain value they can out of the different parts. This often means salvaging valuable materials such as steel, copper, aluminum, certain types of plastics, and precious metals from the housing, cable harness, cooling system, or other electronic parts.

For safety considerations, spent lithium-ion batteries must be stabilized by discharging. Recyclers will also diagnose the current state of health (SOH) of the modules during the process. The SOH is the basis for decision-making if the battery qualifies for reuse, in the sense of repairing or refurbishing to extend the EV battery's service life for second-life applications.

There are two different ways to discharge a cell: The use of an ohmic resistor is the current state-of-the-art, and the use of an electrically conductive liquid, a niche application for small batteries.

Currently, lithium-ion cells are subjected to pyrolysis before mechanical treatment. This mainly aims to deactivate the cells for safety reasons.

The energy content can be reduced in a controlled manner while organic components are removed, and the level of halogenated substances can be minimized by an exhaust gas stream.

During the pyrolysis process, the active materials of both anodes and cathodes are separated from a copper or aluminum foil when the organic binder is removed.

The active material based on LFP-type cathode materials is less reactive and does not need to be discharged before going through pyrolysis, while those using LMO- or NMC- type cathodes are much more reactive and should be discharged before the pyrolysis.

After pyrolysis, the batteries can be stored for short periods, and mechanical treatment can be carried out at low levels of fire or thermal runaways.

Mechanical pretreatment of spent lithium-ion batteries is required prior to metallurgical processes.

In order to make the battery recycling process easier, the sieving and screening process is generally applied as a preliminary treatment before separating and concentrating on metallic contents.

Various sieves are available for the sorting of metal components, which varies depending on their characteristics. More specifically, sieving a crushed sample can provide you with an overall distribution of the values of metals among sizes in the particles.

The coarse fraction of the debris contains components like plastic from the battery case, the separator, elemental Al, and Cu components. The cathode and anode materials dominate the fine fraction as the active portion and are commonly referred to as black mass in industrial jargon.

The final mechanical pretreatment phase involves separation post-crushing and sieving. Components in spent lithium-ion batteries have already been separated and concentrated earlier, which then undergoes the separation process to eliminate the additional impurities, based on their distinctive physical characteristics, thermal properties, density, magnetic characteristics, and wettability property, and electromagnetic behavior.

Commonly used separation technique entails thermal treatment involving calcination at an optimal temperature and atmosphere condition, floatation method typically practiced for the separation of LCO compound from the graphite anode in the presence of Fenton reagent and electrostatic, or magnetic separation technique typically involved to separate magnetically susceptible materials like iron (Fe), Ni, and Co from the non-magnetic components like plastics and separator of battery.

Refining technologies for metal recovery:

The widely adopted pyrometallurgical process, which is extensively applied across the companies involves high-temperature smelting reduction comprising a broad temperature range of 1000 ◦C or more.

This process is typically practiced at a commercial level recycling plant to recover cobalt from the spent lithium-ion batteries. The spent lithium-ion batteries in the preheating zone are burned at temperatures closer to 300 ◦C in order to expel the vaporized electrolyte without any explosion.

However, this process could lead to the generation of a varied class of toxic and harmful gases, including hydrogen fluoride (HF). In the next zone, for instance, the plastic pyrolyzing zone is operated at around 700 ◦C to incinerate the plastic components present in the spent batteries.

In the final zone of smelting and reduction, an alloy of Cu, Co, Ni, and iron (Fe) is formed, along with the production of slag or residue, consisting of Li, Al, Si, Ca, and some portion of iron.

The pyrometallurgical process is a trade-off estimation for the process to consider the recovery of lithium on one hand and the cohort of other important metals on the other.

This method is classified as unproductive for lithium recycling from a commercial perspective since the industrially adopted pyro-techniques have the inclusion of a slag phase in the process that hinders the recyclability of Li, a phase important for the recovery of Co, Mn, and Ni during smelting in order to prevent the oxidation of the alloy form of these metals. This is one of the prime reasons that some industrial recycling enterprises utilize a combination of the pyrometallurgical and hydrometallurgical processes to achieve maximum retrieval efficiency for the metals.

Still, pyrometallurgy is an established, dominant recycling process because of its simplicity, flexibility, and speed. For example, Umicore, Batrec, Sumitomo-Sony, Accurec, Glencore, and other well-known international companies have commercialized pyrometallurgical processes and are developing and utilizing them.

Car manufacturers and their battery suppliers agree on very strict material specifications to meet high-quality requirements, especially for the application of traction batteries.

Consequently, the recycling processes to recover the secondary materials of high quality must also be designed accordingly. The removal of contaminants and the reduction of impurities are two key objectives for these processes in order to avoid downcycling during recycling.

The hydrometallurgical process primarily consists of the initial leaching stage, which is the most fundamental and predominant phase in hydrometallurgy.

It is followed by the recovery stage involving solvent extraction, electrochemical deposition, and chemical precipitation method. These methods also involve precipitation and electrochemical methods to reclaim the useful metals from the leached liquor.

Hydrometallurgy produces higher metal extraction rates and lower emissions than pyrometallurgical processes. It also requires less energy and has a low start-up cost.

Leaching, the critical step involved in this process, helps recover valuable metals from spent lithium-ion batteries. It aims to transform the metals present in black mass, obtained from the pre-treatment process mentioned earlier, into ions.

The leaching of active materials is generally performed by using inorganic acid, organic acid, alkaline or bacteria solutions as leaching media. Sometimes additional measures such as ultrasound and mechanochemistry are also used to enhance the leaching effect.

The following is a summary of the technology and features of battery recycling companies around the world:

Technology and features of global battery recycling companies

*Cu salt *mixed metal oxides

Ultra-high temperature (UHT) technology; closed loop

Efficient combination of 2 metallurgical technologies

Stored and shredded under CO2 atmosphere

A rotary hearth furnace along with reducing pellets

Pyrolysis, distillation, and refinement of metals

Original "directional recycling" mode and global advanced "reverse product position design" technique

Closed loop including leaching, purifying, and resynthesis used

Crushed under the protection of liquid N2; crushed under a water

spray or under nitrogen or both

Shredded by a rotary shearing machine under an inert atmosphere

A mechanical process based on two-stage crushing line followed by the magnetic and mechanical separation unit

A patented method that combines mechanical, thermodynamic and

hydrometallurgical processes to deliver exceptional material

recovery rates despite with low energy consumption

Own patent portfolio including whole battery deactivation, sorting,

harvesting of electrode materials, cathode-healing and clean

Notes. P = Pyrometallurgy, H = Hydrometallurgy, M = Mechanical pre-treatment. Source: Jin, S. et al. (2022, p. 13). Data compiled by DIGITIMES Asia, April 2022.

The cathode and anode components of the spent battery can be recovered via a series of direct recycling processes, where the recovered components can be further used for the manufacture and restructuring of a new battery.

The active materials that are used up in the spent batteries could be recycled and reactivated without any dissolution. When the transition metal materials are in their oxide state, they are integrated with new electrodes which change the morphological, purity, and structural properties only minimally.

After the electrolytes cells have dried up, the cell components are separated by physical methods after disassembly and crushing. The cathode materials are then collected and reused to manufacture fresh batteries along with the incorporation of lithium into the electrodes of new batteries called lithiation.

It's important to make sure that the parts for the battery anode, cathode, electrolyte, and separator are all of extremely high purity. By reusing these parts without keeping in mind their high level of purity you run the risk of causing a battery short circuit or a fire.

The recycling of cathode components is an important issue for sustainability. The direct recycling approach has the potential to help find a sustainable solution and increase industrial recycling efforts.

To give our readers a thorough understanding of the EV battery industry, DIGITIMES Asia will publish ten articles on the subject, which will be divided into three sections:

Section 1: EV battery materials: Researcher highlights three major lithium-ion battery challenges

Section 2: Latest development of major EV battery manufacturers: CATL expediting overseas expansion and tech advancement to maintain worldwide dominance, EV battery startup InoBat Auto to visit Taiwan, and swapping battery versus charging

Section 3: EV battery recycling industry reports: Part 1: Europe takes the lead in EV battery recycling, Part 2: second-life batteries future opportunities and challenges, Part 3 & 4: EV battery recycling current technologies, Part 5: EV battery recycler, and Part 6: EV battery recycling technology startup

This is the fourth part of the EV battery recycling industry reports.