Recycling in the area of stationary large battery storage systems

6 mins

Batteries are among 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 increasing rapidly. The ongoing energy revolution also means a transition from dependence on fossil fuels to dependence on metals — the mainstay of our future energy storage.

The European Commission predicts that global demand for batteries will increase 14-fold by 2030, with the EU alone responsible for 17 percent of this increase. This growth also affects the highly dynamic market for stationary large battery storage systems, which has become a focus market and core issue, particularly in the energy transition. The lithium-ion battery alone, the predominant battery technology in the stationary battery storage market, achieved global market demand of almost one terawatt hour in 2023. As a result, the battery market is becoming increasingly strategically important. But with increasing demand and production, another crucial issue is coming into focus: the recycling of batteries.

So how does recycling work in the area of stationary large battery storage systems from a technical point of view and what is the legal basis for this? In the course of the blog article, we will provide an overview of this.

Recycling from a technical perspective

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

As part of the discussion about recycling 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.

Distinctive differences are particularly noticeable in the cathode and illustrate a central problem in the recycling process. The diversity of cathodes' cell chemistries results in 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 with a residual capacity of 80%, while in stationary use 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 stationary areas allow a longer operating time. This is also one of the reasons why the cells in stationary large battery storage systems last longer than in the automotive sector. Many of the second-life concepts therefore also provide that a secondary application of traction batteries (batteries that are used to drive electric vehicles and other electric means of transport) is the stationary sector. However, reuse (second-life) and re-use (second-use) after reaching the end of life are less practicable in the stationary sector compared to the automotive sector, so recycling is of great importance for this area, as a larger number of battery cells reach their actual end of life here.

Presentation of technical processes

The recycling process of batteries is divided into various phases, although the specific processes may vary. The overall goals and exemplary steps are described below.
In addition to the recycling steps mentioned above, aspects such as collection, transportation, storage, testing and unloading are also highly relevant to enable the recycling process.

Preparation: The preparation and preparation of the battery modules ensures that the materials can be processed safely and efficiently. This includes unloading and disassembling the modules, which are 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 deep-discharged battery modules, free of peripheral components such as cooling or cables. Even in this process step, raw materials such as aluminum and copper, plastics or electronic components can be obtained, which can account for up to 25-30% of the total mass of the battery.

Pretreatment: The dismantled battery modules are then shredded and sorted to be further processed as “black mass”. Sorting is an often underestimated, important step here. The fewer impurities in the black mass, the higher qualities can be achieved in the end products and thus make 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 to decompose unwanted substances. A thermal pretreatment performs various functions, including the removal of organic elements (e.g. electrolyte) and the decomposition of the polymeric binder (e.g. polyvinylidene fluoride PVDF). It is preferred to remove organic solvents to avoid contamination in subsequent recycling steps.

Black Mass Excursus: The term “black mass” refers to the material that remains after the pretreatment and mechanical reduction of lithium-ion batteries. It is a dark, often black powder that contains a wide variety of substances, including cathode material, anode material, electrolyte residues, and potential contaminants. A lower amount of impurities in the black mass makes it possible to obtain substances of higher purity. The ideal black mass consists only of the materials of the electrodes. The 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, there are various technical processes available to recycle lithium-ion batteries. These processes can be divided into two main categories: the pyrometallurgical process and hydrometallurgical process — 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 preprocessing steps are required, and the decomposition of polymeric binders described above is not absolutely necessary. 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 substances such as fluorine. During melting, the input materials are decomposed in an oven 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 for recovering transition metals. Accordingly, it is used in particular for the extraction 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 “contaminants” caused by 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 oven and are therefore not recovered. However, their combustion provides heat energy for the process and replaces other sources of fuel. Some of these intermediates can be used for lower value applications in other industries. For example, slag is reused in the construction industry.

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

Hydrometallurgical process:

In hydrometallurgy, the materials are dissolved. The metals are then extracted from the solution through 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 is generally followed by the following three steps:

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

In general, the hydrometallurgical process allows the recovery of a wider range of substances compared to the pyrometallurgical process. However, extracting the substances requires a targeted selection of the solvents. In addition, increased water consumption can be expected. In addition, the solvents produce waste materials that must be further processed and disposed of. As a technology, the hydrometallurgical recycling process is more complex and even less sophisticated, which means that the costs are comparatively higher. However, from a purely technical point of view, it allows the additional recycling of substances that would otherwise be lost. In this way, in addition to metals, other substances such as graphite or lithium could also be recovered.

The following figure shows the material flows that can already be recycled according to current industrial standards, using NMC cell chemistry as an example.

Core problem when recycling lithium-ion batteries

A major challenge in the area of recycling lies in the heterogeneity of battery cells that are available on the market. Lithium-ion batteries, for example, differ fundamentally in their cell chemistry and cathode composition. For stationary large battery storage systems, cathodes are mainly used with LFP cells, while NMC cell chemistry still prevails in automotive applications. At the time of delivery, the recycling company is often not aware of the specific cell chemistry and components involved.

Recycling regulations

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 regulations for recycling 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 Act regulated the marketing, withdrawal and environmentally friendly disposal of batteries and accumulators. Take-back obligations by the distributor, requirements for the recycling and disposal of old batteries and initial recycling quotas were already set out here. However, the Directive was also interpreted and implemented differently by the various member states.

The battery regulation

With the introduction of the EU Battery Regulation on August 18, 2023, the legal basis is being promoted more specifically and with more emphasis and making all market players, but in particular suppliers and distributors, from the battery industry 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, and the life cycle of batteries in terms of climate neutrality and environmental protection. The regulatory framework covers various aspects, from the production and marketing 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 stationary large battery storage systems also fall under the provisions of the ordinance as “industrial batteries”.

The stricter battery regulations will gradually come into force between 2023 and 2036 and call for new circular partnerships between industry and users. The specific measures of the regulation include increasing the recycling rate, using more recycled materials in the production of new batteries and the introduction of “battery passports” to ensure traceability.

The previous requirements (BattG2) for recycling batteries provided 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 are 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 are set for lithium, cobalt, copper, nickel and lead in batteries. For example, the mandatory recycling rate for lithium will rise 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, which should rise to 95% by 2032.

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

The requirements for recycled material content will also be tightened with the new battery regulation and oblige manufacturers to provide information more transparently. From August 18, 2031, industrial batteries and thus also in large stationary battery storage systems must contain a “minimum proportion of cobalt, lithium or nickel recovered from battery production waste or from consumer waste” (Battery Ordinance, Article 8, § 2). The following recycling quotas were recorded:

  • 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 requirements both with regard to general recycling rates and recycled content, depending on actual market developments.

In order to simplify and standardize the disposal, recycling and traceability of batteries, the digital battery passport is also being introduced, which is aimed primarily at economic operators and recycling companies. From February 18, 2027, all new batteries must therefore have a QR code, which summarizes all their information in an electronic file, under the responsibility of the manufacturer. 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, conversion and disassembly, and the recycling and recovery processes are stored digitally. The information can be retrieved at any point in the life cycle of a battery. The battery pass 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 use of batteries more strictly, but above all require new partnerships between industry and battery users. In line with the circular objectives of the European Green Deal, this regulation is the first European piece of legislation to take a complete life-cycle approach for batteries. The new regulation thus marks an important step towards more sustainable battery production.
Current regulations have so far focused on NMC cell chemistry, which includes transition metals such as cobalt, copper and nickel. Even with regard to the materials to be recycled, the pyrometallurgical process cannot only be used, because lithium must also be recycled. Hydrometallurgical processes will therefore become essential for battery recycling in the future. It is also exciting to see how the recycling of LFP battery modules is developing. In contrast to NMC, this contains less precious materials, and yet the quotas based on the total recycled mass must be met.

The effects of the new EU battery regulation will only become clear in the future. The market for stationary large battery storage systems is relatively young and is characterized by very dynamic growth. Numerous large battery storage projects have only recently been completed. Due to the long life expectancy of batteries in stationary use, which is up to 20 years, mainly batteries from the automotive sector are currently in the ongoing recycling process. However, with increasing demand, production and implementation of these projects, it is expected that the market will continue to grow significantly and will require appropriate resources to do so. This applies in particular against the background of the evaluation of LFP chemistry and the physical and sustainable nature of the raw materials it contains.

Ansehen & Download
Dokument ansehen