Recycling in the field of stationary large-scale battery storage systems

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Batteries are one of the key elements of green mobility, clean energy supply and climate-neutral development. In the past, their importance in the various sectors has increased significantly and the demand for batteries is also growing rapidly. The ongoing energy transition also means a transition from dependence on fossil fuels to dependence on metals - the mainstay of our future energy storage.

The European Commission forecasts that global demand for batteries will increase 14-fold by 2030, with the EU alone accounting for 17% of this increase. This growth also affects the highly dynamic market for large-scale stationary battery storage systems, which has become a focus market and core topic, particularly in the energy transition. Lithium-ion batteries alone, the predominant battery technology in the stationary battery storage market, will reach a global market demand of almost one terawatt hour in 2023. This means that the battery market is becoming increasingly strategically important. However, with rising demand and production, another crucial issue is coming into focus: the recycling of batteries.

So how does recycling in the field of stationary large-scale battery storage systems work from a technical perspective and what is the legal basis for this? We will provide an overview of this in the course of the blog article.

Recycling from a technical perspective

Components of a state-of-the-art lithium-ion cell

When discussing the recycling of lithium-ion batteries (LiB), it is essential to understand that there is no uniform standard battery cell. Rather, they are heterogeneous products that can differ both in their manufacturing processes and in their material and raw material composition. The following figure illustrates the components of such a cell and their typical weight distribution, as is common on the current market.  

Striking differences are particularly noticeable in the cathode and illustrate a central problem in the recycling process. The variety of cell chemistries of the cathode leads to a variation of the substances contained in the cell and therefore requires different recycling processes.

Second-Life & Second Use

In the automotive industry, a battery cell reaches the end of its life at a residual capacity of 80%, whereas in the stationary sector it is normally used up to a residual capacity of 60%. These differences result from the different requirement profiles of the two areas. The gentler, less heavy load profiles in the stationary range allow a longer operating time. This is also one of the reasons why the cells last longer in the stationary large-scale battery storage sector than in the automotive sector. Many of the second-life concepts therefore also envisage a secondary application for traction batteries (batteries used to power electric vehicles and other means of electric transportation) in the stationary sector. For the stationary sector, however, second-life and second-use after reaching the end of life are less practicable compared to the automotive sector, so recycling is of great importance for this sector, as a larger number of battery cells reach their actual end of life here.

Presentation of the technical processes

The battery recycling process is divided into various phases, whereby the specific procedures can vary. The overarching objectives and exemplary steps are described below.
In addition to the recycling steps mentioned, aspects such as collection, transportation, storage, testing and discharging are also highly relevant in order to facilitate the recycling process.  

Preparation: The preparation and conditioning of the battery modules ensures that the materials can be processed safely and efficiently. This includes discharging and dismantling the modules, which is typically carried out manually. One challenge is the heterogeneous cell chemistry and composition of lithium-ion batteries, which is why pre-sorting takes place before treatment. The aim is to obtain deeply discharged battery modules, free of peripheral components such as cooling or cables. Raw materials such as aluminum and copper, plastics or electronic components can already be recovered in this process step, which can account for up to 25-30% of the total mass of the battery.  

Pre-treatment: The dismantled battery modules are then shredded and sorted for further processing as "black mass". Sorting is an important step that is often underestimated. The fewer impurities contained in the black mass, the higher the quality of the end products can be, making a circular economy possible in the first place. In this process, targeted heating to a specific temperature is often used to trigger chemical reactions or decompose undesirable substances. Thermal pre-treatment fulfills various functions, including the removal of organic elements (e.g. electrolyte) and the decomposition of the polymer binder (e.g. polyvinylidene fluoride PVDF). It is preferred to remove organic solvents to avoid contamination in subsequent recycling steps.  

Digression on black mass: The term "black mass" refers to the material that remains after the pre-treatment and mechanical reduction of lithium-ion batteries. It is a dark, often black powder that contains a variety of materials, including cathode material, anode material, electrolyte residues and potential impurities. A lower amount of impurities in the black mass enables the extraction of materials with higher purity. The ideal black mass consists only of the materials of the electrodes. Further processing and treatment of the black mass is an important step in the battery recycling process in order to recover valuable resources.

Main treatment: Today, various technical processes are available for recycling lithium-ion batteries. These processes can be divided into two main categories: the pyrometallurgical process and hydrometallurgical processes - both can also be used in combination.

Pyrometallurgical process:  

The pyrometallurgical process is based on established technology that has been used in the metal industry for decades. In the case of battery recycling, metals are extracted by melting the black mass. This separation is based on the different melting points and chemical-physical properties of the metals and other components. Only minimal pre-processing steps are required and the previously described decomposition of polymeric binders is not necessarily required. The process produces various products, including metal alloys, slag with aluminum and lithium, and fly ash with fine particles that may contain metal oxides, carbon residues from organic battery components and inorganic materials such as fluorine. During smelting, the input materials are decomposed in a furnace at around 1500˚C in the presence of a reducing agent and additives such as quicklime and silicon dioxide ("slag formers").  

The pyrometallurgical process is well suited to recovering transition metals. Accordingly, it is used in particular for the recovery of rare metals such as nickel and cobalt. At the same time, it is a robust process that can continue to achieve good results even with "impurities" from a different cell chemistry. An overview of the material flows for NMC cell chemistry is shown in the following figure.  

Other non-metallic materials, such as the graphite anode and polymers from the housing and separator, burn in the furnace and are therefore not recovered. However, their combustion provides thermal energy for the process and replaces other fuel sources. Some of these intermediate products can be used for lower value applications in other industries. For example, slag is reused in the construction industry.

To recover further materials, the products of pyrometallurgy must be subjected to further processing using hydrometallurgical techniques.  

Hydrometallurgical process:

In hydrometallurgy, the materials are brought into solution. The metals are then extracted from the solution using various chemical processes such as precipitation or electrolysis in order to recover them in a suitable format. These wet-chemical processes allow precise control of raw material extraction and offer an alternative to pyrometallurgical processes. The recovery of raw materials basically follows the following three steps:

  • Leaching: Acid, base or salt is used as a solvent to dissolve the incoming materials of the black mass
  • Purification: Impurities are removed and metals in the solution are separated by selective chemical processes (e.g. ion exchange or solvent extraction)
  • Recovery from solution: Separated metals are recovered as solid products using techniques such as precipitation, crystallization or electrolysis

In general, the hydrometallurgical process enables the recovery of a wider range of substances compared to the pyrometallurgical process. However, the extraction of the substances requires a specific selection of solvents. In addition, increased water consumption must be assumed. The solvents also produce waste materials that have to be additionally treated and disposed of. As a technology, the hydrometallurgical recycling process is more complex and even less mature, which means that the costs are comparatively higher. From a purely technical point of view, however, it enables the additional recycling of materials that would otherwise be lost. In addition to metals, other substances such as graphite or lithium can also be recovered.

The following illustration shows the material flows that can already be recycled according to current industry standards, using the example of NMC cell chemistry.  

Core problem with recycling lithium-ion batteries

A major challenge in the field of recycling lies in the heterogeneity of the battery cells available on the market. Lithium-ion batteries differ fundamentally in their cell chemistry and cathode composition. LFP cathode cells are predominantly used for stationary large-scale battery storage, while NMC cell chemistry is still predominant in the automotive sector. It is often not clear to the recycling company at the time of delivery which specific cell chemistry and components are involved.

Regulation in the area of recycling

The development of a (battery) circular economy in Europe is also supported by regulatory initiatives. The focus on legal requirements has increased significantly in recent years.  

In the past, the provisions on the recycling of batteries in Germany were regulated by the Battery Act (BattG). It came into force in 2009 as an implementation of the EU Directive (2006) and was comprehensively amended in 2021 (BattG2). The law regulates the placing on the market, take-back and environmentally sound disposal of batteries and accumulators. It already stipulated take-back obligations for distributors, requirements for the recovery and disposal of waste batteries and initial recycling quotas. However, the directive was also interpreted and implemented differently by the various member states.

The Battery Ordinance

With the introduction of the EU Battery Regulation on August 18, 2023, the legal basis will be more specific, promoted with more emphasis and all market players, but especially suppliers and distributors, from the battery industry will be held more accountable. The regulation is considered one of the cornerstones of the European Commission's European Green Deal, which aims to improve the circular economy, resource use and efficiency as well as the life cycle of batteries in terms of climate neutrality and environmental protection. The regulatory framework covers various aspects, from the production and placing on the market of batteries to performance requirements, recycling and the provision of materials for the production of new batteries. The regulation thus pursues a complete life cycle approach. Batteries such as those found in large-scale stationary battery storage systems are also covered by the provisions of the regulation as "industrial batteries".

The stricter battery regulations will come into force in stages between 2023 and 2036 and call for new circular partnerships between the industry and recyclers. Specific measures in the regulation include increasing the proportion of recycled materials, using more recycled materials in the production of new batteries and introducing "battery passports" to ensure traceability.

The previous requirements (BattG2) for the recycling of batteries stipulated that
at least 65% of the average mass of waste lead-acid batteries, 75% of the average mass of waste nickel-cadmium batteries and 50% of the weight of a battery must be recycled. With the introduction of the Battery Ordinance, these requirements will be significantly increased and specified. From 2026, the quota for lithium-ion batteries will be increased to 65% and from 2031 to 70%. In addition, specific recycling targets will be set for lithium, cobalt, copper, nickel and lead in batteries. For example, the prescribed recycling rate for lithium will increase from 50% to 80% between 2028 and 2032. For cobalt, copper, nickel and lead, the EU is aiming for a recycling rate of 90% from 2028, rising to 95% by 2032.

Recyclers are obliged to report annually on the quantity of batteries treated and recycled as well as the recycling rates of the various materials recovered. They must also regularly measure the efficiency of their recycling processes.

The specifications for the recycled content will also become stricter with the new Battery Ordinance and oblige manufacturers to provide more transparent information. From August 18, 2031, industrial batteries and therefore also large battery storage systems in stationary operation must contain a "minimum proportion of cobalt, lithium or nickel recovered from battery production waste or consumer waste" (Battery Ordinance, Article 8, Section 2). The following recyclate quotas were specified:

  • 2031: 16% cobalt, 85% lead, 6% lithium, 6% nickel
  • 2036: 26% cobalt, 85% lead, 12% lithium, 15% nickel

The European Commission reserves the right to adjust the targets for both the general recycling quotas and the recycled content, depending on actual market developments.

In order to simplify and standardize the disposal, recycling and traceability of batteries, the digital battery passport will also be introduced, which is mainly aimed at economic operators and recycling companies. From February 18, 2027, all new batteries under the responsibility of the manufacturer must therefore have a QR code that summarizes all their information in an electronic file. For example, information on the CO2 intensity of their manufacturing processes, the origin of the materials used, their composition (including raw materials and hazardous chemicals), the processes of repair, reuse and dismantling, and the recycling and recovery processes will be stored digitally. The information can be retrieved at any time during the life cycle of a battery. The battery passport is only deleted once the battery has been recycled.


The stricter rules of the EU Battery Regulation not only signal the EU's will to regulate the handling of batteries more strictly, but above all require new partnerships between the industry and the recyclers of batteries. In line with the circular objectives of the European Green Deal, this regulation is the first European legislation to take a full life-cycle approach to batteries. The new regulation marks an important step towards more sustainable battery production.
In the current regulatory framework, there has so far been a clear focus on NMC cell chemistry, which includes transition metals such as cobalt, copper and nickel. The pyrometallurgical process alone cannot be relied on with regard to the materials to be recycled, as lithium also has to be recycled. In the future, hydrometallurgical processes will therefore become essential for battery recycling. It is also exciting to see how the recycling of LFP battery modules will develop. In contrast to NMC, these contain fewer valuable materials, but the quotas in relation to the total recycled mass still have to be met.  

The effects of the new EU Battery Regulation will only become clear in the future. The market for stationary large-scale battery storage is comparatively young and is characterized by very dynamic growth. Numerous large-scale battery storage projects have only recently been realized. Due to the long life expectancy of batteries in stationary operation, which is up to 20 years, it is mainly batteries from the automotive sector that are currently in the ongoing recycling process. However, with the increasing demand, production and implementation of these projects, it is expected that the market will continue to grow significantly and will require corresponding resources. This is particularly true in light of the evaluation of LFP chemistry and the material and sustainable nature of the raw materials it contains.  

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