Recycling lithium-ion batteries is essential for sustainability: once they reach the end of their useful life, they must be disposed of correctly. In this sense, there are certain technical aspects to take into account in order to give a "second life" to this type of storage device. We will look at the key issues below, from the difference between physical and chemical processing to the different phases that are usually involved in the reuse of batteries.
Recycling processes for battery recovery: physical and chemical processing
Recycling lithium batteries involves various processes to recover the battery components and reduce the amount of waste. There are two main types of processes: physical and chemical.
1. Physical processes
Physical processes are a fundamental part of lithium battery recycling, as they are responsible for the pre-treatment of the battery components before chemical processes are carried out. These physical processes are based on the use of different physical characteristics of the materials present in the battery, such as density, magnetic properties and solubility, to separate the cathode and anode materials from other components such as current collectors and electrolytes.
One of the most common physical processes is the disassembly of the battery, where the different components of the battery such as the casing, electrolyte and current collectors are separated. Once separated, the components are crushed and undergo a separation process in which flotation, magnetic separation and density separation techniques are used to separate the different materials present in the battery.
In the separation process, battery materials are sorted into different fractions based on their physical properties. For example, casing material can be separated by magnetic separation, as it is attracted by a magnet, while heavier materials such as current collectors are separated by density.
2. Chemical processes
The chemical processes for the recycling of lithium batteries are based on the extraction of the active components of the battery through the use of solvents, reagents and acids that allow the separation of the different metals found in the battery, such as lithium, cobalt, nickel, manganese, among others.
Hydrometallurgical processes are the most widely used for the recycling of lithium batteries due to their selectivity in the recovery of metals and the reduction of toxic gas emissions compared to pyrometallurgical processes. Within hydrometallurgical processes, different techniques are used for the recovery of lithium battery materials. Some of these techniques are acid leaching, solvent extraction, electrowinning and chemical precipitation.
Pyrometallurgical processes are one of the most common forms of chemical processing for recycling lithium batteries. In this process, the metallic components of the battery are recovered by melting at high temperatures (typically between 800-1300°C), which allows the different metals to melt and separate. The metals are recovered in the form of alloys, such as copper, cobalt, nickel and iron, which can then be refined into high-purity metal components.
This process has the advantage of being relatively simple and productive for the recovery of metallic materials, but is not suitable for the recovery of organic materials. In addition, the slag resulting from the process may contain a variety of components, including metals and other materials, which can make it difficult to dispose of properly.
Fig. A Recycling processes and schemes 
The seven processes for recycling lithium batteries
In order to recycle lithium batteries efficiently and cost-effectively, we propose 7 key steps that are adapted to the complexity of the batteries and the recycling strategies of each plant.
- PreselectionBattery evaluation: In this process, an initial assessment of the batteries is made to determine their condition, size and type. It also checks for defective or damaged batteries that are not suitable for recycling.
- Energy recoveryLithium cells or batteries contain energy and it is important to remove this energy safely before processing the battery for recycling. This process removes hazardous liquids and gases that may be released when the battery is handled.
- DismantlingDismantling: In this process, the battery is dismantled to separate its components and parts. Most lithium batteries are dismantled manually, but some automated processes are also being developed.
- DecontaminationLithium batteries contain hazardous chemicals, such as acids and heavy metals, which must be carefully treated to prevent their release into the environment. This process removes contaminating materials and decontaminates the battery parts. It includes cryogenic treatment, around -200°C, which prevents exothermic reactions during the later stages of the recycling process and/or pyrolysis and calcination heat treatments to remove organic and flammable components.
- ReleaseOnce the battery has been disassembled and decontaminated, its components are separated. This process may involve crushing or grinding the battery into small pieces to facilitate separation.
- SeparationSeparation: In this process, the materials that make up the battery, such as cobalt, nickel, lithium and iron, are separated. Physical and chemical processes are used to separate the materials and purify them for further use.
- Metallurgical refiningOnce the materials have been separated, they are refined. This technique can be thermal (pyrometallurgical processes), chemical (hydrometallurgical processes) or even biological (biometallurgical processes).
Recovery of materials from the lithium battery
Comparing the two lithium battery recycling processes, and looking at pyrometallurgical vs. hydrometallurgical, what advantages does each offer?
- Pyrometallurgical methods are more expensive in terms of energy and materials, but produce metals that can be sold.
- Hydrometallurgical methods can yield high quality materials for reuse in new batteries, making them potentially more efficient, but they are more complex and require more steps and chemicals.
However, hydrometallurgical methods have a significant advantage in terms of metal recovery. They can recover up to 100% of lithium and cobalt, 98% of manganese and 75% of aluminium in the form of cathode/anode materials ready for use in new batteries. However, this depends on whether the recycling process is profitable in terms of costs and revenues.
Fig. B: Example diagram of pyrometallurgical and hydrometallurgical processes for the recycling of NiMH, LMO and LCO batteries. 
The table below presents several examples of metals and products that can be recovered from end-of-life lithium batteries through different recycling processes. The table also indicates the purity that can be obtained from each of them, which ranges from 90% to 100%.
Fig. C: Summary of metals and chemicals obtained from the recycling of used Libs 
The table indicates that it is possible to recover both pure metals (cobalt, nickel, copper) and products usable to produce new cathode materials (carbonates, sulphates and hydroxides of various metals) from spent cathodes in different types of lithium batteries, such as LCO (LiCoO2), LFP (LiFePO4), LMO (LiMn2O4), NMC (LiNi1/3Co1/3Mn1/3O2) and NCA (LiNi0.8Co0.15Al0.05O2), through physicochemical processes.
The recycling process of the future
The recycling process currently used for lithium batteries involves obtaining the basic elements and compounds for the creation of new active materials from a "black mass". This black mass is a slurry of cathode and anode materials that still needs to be refined, resulting in a waste of energy and other materials.
Fig. D: Actual recycling process 
In order to improve efficiency, the aim is to switch to a "direct recycling" process. This aims to directly recycle the active materials as much as possible, avoiding the transformation into black mass and the need for refining and resynthesising the cathode and anode materials. This process also involves the implementation of collection systems based on the health of the modules and cells, which facilitates and speeds up the sorting phase.
In addition, the mechanical design of the batteries will take into account the disassembly that will take place at the end of their life, which will facilitate the disassembly in the recycling process. Active materials will be recovered and regenerated as far as possible, and only the non-regenerable part will be processed into primary components.
Compared to the current process, direct recycling results in higher energy efficiency and a significant reduction of waste. Regenerated materials can be reused in the new cell production cycle, starting the cycle all over again.
Fig. E: Future recycling process 
To achieve optimal recovery in the recycling process, it is important to accurately select the materials to be recycled and their specific chemistry. To achieve this, the traceability of cells needs to be improved through technologies such as tags and RFID, which uniquely identify their composition and state of life. However, the recycling process is challenged by the ever-decreasing costs of cells, which requires more convenient and efficient recycling processes.
Currently, there are different recycling processes specialised in one type of battery to achieve high efficiencies.
- The Umicore and Sumitomo-Sony processes allow products that can be blended with virgin materials for use in new batteries without sacrificing their final quality.
- The Recupyl process in addition to cobalt, allows the recovery of LiFePO cathodes 4 and LiPF electrolyte 6
- Umicore-Valéas and Sumitomo-Sony processes electrolytes, plastics, organic materials, metals and graphite are not recovered for direct use but are partially used as by-products for the construction industry, thus devaluing their value.
Currently, recycling of LiFePO 4 and LiMn 2 O 4 batteries is limited due to their low market value, but these chemicals are increasingly being used in the energy industry. As the production of LiFePO 4 batteries increases, recycling is expected to increase and costs will be reduced. In addition, this type of battery is safer than other materials and its use is expected to expand in the future.
Fig. F: Battery chemistry market share forecast, 2015 - 2030 
Second Life lithium battery: a solution that can be combined with recycling that should not be underestimated.
More and more studies are talking about giving a second life to end-of-life lithium batteries in electric vehicles. This solution involves recovering and reusing the spent battery for other purposes, such as energy storage, before recycling it.
Re-use prolongs the overall lifetime of the battery and reduces the environmental impact of production, recycling and disposal. Depending on the type of use, the second life of a battery can last even longer than 10 years.
In general, the practice of Second Life can extend the overall life of the battery and reduce its environmental impact, but its feasibility depends on the specific application and the uniformity of batteries on the market.
In the automotive sector, batteries are produced in large volumes and are more uniform, which facilitates the reuse of batteries at the end of their useful life for other purposes.
NCPOWER lithium batteries? More and more attentive to the issue of recycling and sustainability
At NCPOWER we focus on sustainability in all aspects of our corporate vision, from the energy efficiency of our plant to the design of our batteries.
The Research and Development department is central to this strategy, not only to anticipate customer needs with innovative products, but also to find more environmentally friendly solutions.
NCPOWER uses LFP chemistry in its batteries, which is safe, stable and completely free of cobalt, a material that has a high environmental impact. In addition, the R&D department is actively studying more eco-sustainable production processes and materials in order to optimise the various production steps and the design of the batteries.
We know there is a long way to go, but NCPOWER is confident that investing in materials and skills aimed at efficiency and sustainability can make a great contribution on the road to a green society.
 https://pubs.rsc.org/en/content/articlelanding/2018/cs /c8cs00297e/
 Wood Mackenzie's energy storage service