Risk Assessment and Management of End-of Life Lithium-Ion Batteries

Synthesis

Disclaimer: The content of this publication is based on the state of knowledge and the regulatory framework in force at the time of publication of the documents.

Context of the study

The rapid electrification of the transport sector has become a key driver of the energy transition and the decarbonisation of the European economy. Public policies aimed at reducing greenhouse gas emissions are encouraging the growing adoption of electric vehicles and light electric mobility solutions such as e-scooters, bicycles, and electric scooters. This shift, driven both by increasingly stringent regulatory requirements and by accelerating technological innovation, as well as evolving societal expectations, is accompanied by an exponential increase in the number of lithium-ion batteries in circulation across Europe.

End-of-life management of these batteries now raises economic, environmental, and industrial safety challenges of unprecedented magnitude. These high-energy-density storage systems contain reactive materials and flammable electrolytes which, if improperly handled or poorly monitored, can lead to fires, explosions, or severe contamination of natural environments. As the European recycling and reuse sector for batteries is still in the process of structuring and scaling up, it faces a dual challenge: on the one hand, ensuring robust risk control, and on the other hand, guaranteeing the efficient recovery of the critical resources embedded in these batteries.

In this context, this in-depth study was undertaken to assess the risks associated with the end of life of lithium-ion batteries. Its objective is to support public and private stakeholders in developing safe and sustainable practices based on consolidated scientific knowledge and operational feedback from the field.

Objective and scope of the study

The study aims to assess the wide range of risks associated with the end of life of lithium-ion batteries and to propose concrete and actionable measures to prevent their impacts on health, safety, and the environment. It focuses particularly on batteries from end-of-life vehicles (ELVs) and small mobility devices, while considering all stages of the value chain: collection, sorting, storage, transport, reuse, and recycling.

The approach adopted combines documentary research and operational feedback. An in-depth literature review drew on data from the ARIA database managed by the Bureau for Analysis of Industrial Risks and Pollution (BARPI), recent reports from INERIS and CNPP, as well as several international databases (OSHA, CSB, FEMA, eMARS). Interviews were also conducted with key stakeholders in the sector, including producer responsibility organisations (Corepile, Ecologic), treatment operators, vehicle manufacturers, and public bodies.

This dual scientific and operational approach made it possible to develop a detailed overview of the current situation, identify recurring causes of incidents, and evaluate existing gaps. The work was structured around two main components: first, the establishment of a detailed risk diagnosis, and second, the formulation of recommendations to improve prevention and the management of critical situations.

Key findings and insights

Accident trends and risk typology

The analysis highlights a steady rise in the number of recorded incidents and an increasing diversity of risks, exacerbated by the growing volume of batteries in circulation and the fragmentation of management practices. Between 2014 and 2022, more than 570 accidents were recorded in France within facilities classified under NAF code 38 (waste collection, treatment, and disposal). These incidents are concentrated mainly in sorting centres, storage platforms, and treatment facilities, with strong seasonality observed during the warmer months. Heatwaves tend to increase the likelihood of fires or explosions (BARPI, 2023).

The most frequently identified causes include a lack of proper sorting upstream, inadequate handling practices (often involving mechanical grapples or occurring during dismantling), short circuits linked to damaged or punctured modules, outdoor storage without adequate protection, and overly dense storage conditions. These factors have led to sometimes spectacular fires, releasing toxic fumes, contaminating soil and water resources, causing the evacuation of nearby populations, and resulting in significant material losses. The challenges faced by fire and emergency services, which must sometimes deal with non-compliant facilities, insufficient safety measures, or poorly identified batteries, further aggravate the severity of such incidents.

Nature and magnitude of the risks

The identified risks fall into four interdependent categories: physical, chemical, toxicological, and environmental. Each of these dimensions contributes to a complex risk landscape that must be understood holistically to ensure safe end-of-life management.

Physical risks first include electrical hazards. Even at the end of their life, lithium-ion batteries retain residual voltage that can exceed several hundred volts, enough to cause electric shock or electrocution through direct contact or improper handling. Operations such as dismantling, shredding, or mechanical sorting are particularly sensitive, especially when insulating protections are damaged. Contact with water, either due to non-watertight storage or during firefighting operations, further increases the risk by promoting the formation of electrical arcs.

Thermal risk constitutes another major concern. Thermal runaway, often triggered by an internal short circuit, overheating, or mechanical shock, leads to a rapid rise of temperature and the release of large amounts of energy. This phenomenon can propagate from one cell to another and, at the level of a module or an entire battery pack, can give rise to extremely intense fires. Recorded temperatures can exceed 800°C, making any intervention extremely difficult and hazardous for emergency responders, even when protective equipment is used.

Explosive atmospheres (ATEX) represent an additional significant danger. When a battery undergoes thermal runaway, it releases gases such as hydrogen, carbon monoxide, and light hydrocarbons. Hydrogen, in particular, has a very low ignition energy and a wide explosive range. If these gases accumulate in an enclosed or poorly ventilated space, they can trigger sudden and violent explosions. Added to this is the risk of projectiles: the rupture of battery casings and the presence of molten metals can propel hot fragments at high velocity, damaging surrounding equipment and posing a direct threat to personnel.

Chemical risks mainly stem from the release of toxic gases during fires or thermal runaway. A lithium-ion battery emits a complex mixture of compounds such as hydrogen fluoride (HF), hydrogen chloride (HCl), carbon monoxide (CO), organic solvents, and hydrocarbons, some of which are corrosive or asphyxiating. The total volume of gas released depends on the battery chemistry and its state of charge. At full charge, a single cell can emit up to 1.5 litres of gas per ampere-hour, part of which is flammable. These emissions present a dual hazard: they facilitate the spread of fire and expose workers and first responders to highly toxic substances (Gully, 2019).

The toxic effects of these emissions are well documented. Upon contact, the liquid electrolyte, composed of organic carbonates and lithium salts (LiPF₆), can cause severe skin and eye burns. Through inhalation, vapours and smoke, notably those containing HF and CO, can lead to respiratory irritation, neurological disorders, and, at high concentrations, may become fatal. Reference values published by INERIS and the U.S. EPA indicate that exposure to only a few tens of ppm of HF can become dangerous in under ten minutes. Chronic exposure, even at low concentrations, may cause cumulative and irreversible respiratory, joint, or bone damage (INERIS, 2024).

Environmental impacts are also significant. Damaged batteries can release electrolytes and heavy metals that contaminate soil, groundwater and surface waters. Firefighting runoff frequently contains pollutants at concentrations far above regulatory limits and therefore requires specific treatment before discharge. The high acidity of these waters and the presence of fluorinated compounds or per- and polyfluoroalkyl substances (PFAS) increase risks for aquatic environments and wastewater treatment systems (INERIS, 2024). In addition, inadequate treatment or uncontrolled export of shredded residues, known as “black mass,” to third countries with weaker environmental standards can lead to the emission of hazardous metal dust and exposes workers to toxic concentrations that can exceed legal thresholds by several orders of magnitude.

European trends and outlook

European projections confirm a rapid increase in end-of-life battery volumes over the next two decades. According to Transport & Environment (2024), the number of electric vehicle batteries reaching their first end of life could range from 58 to 150 GWh by 2035 and rise to as much as 345 GWh by 2040. For light mobility devices, estimates lie between 42 and 52 GWh within the same period. Without significant improvements in collection, sorting, and treatment infrastructure, these growing volumes are likely to multiply industrial and environmental incidents. At the European level, the number of accidents could increase from a few thousand per year to several tens of thousands by 2040 if current practices remain unchanged (RECORD, 2023).

Several factors could, however, help mitigate this trend: the enhancement of safety protocols, tighter regulatory requirements, improved operator training, the automation of sorting and recycling processes, and the deployment of the battery passport to improve traceability. Conversely, other factors may worsen the risks: the absence of standardisation for light mobility batteries, inadequate storage conditions, the rise of new chemistries such as sodium-ion that are not yet fully mastered, the ageing of repurposed batteries used in stationary storage, and the persistence of informal channels that escape regulatory oversight.

Regulatory and standardisation framework

From a regulatory perspective, the European framework continues to evolve and adapt to the rapid expansion of the battery sector. Regulation (EU) 2023/1542 introduces new and more stringent requirements concerning sustainability, traceability, and safety, but several areas remain insufficiently addressed. Existing standards (EN, ISO, UL) primarily apply to new batteries and do not systematically consider thermal propagation phenomena or the diversity of emerging chemistries. Conversion kits for e-bikes, for example, are not covered by any specific standard due to the absence of a harmonised industrial definition. Similarly, criteria for assessing the state of health (SoH) of reused batteries vary between manufacturers and applications, limiting comparability and the reliability of diagnostics.

Analysis, prevention and recommendation

Given the diversity and severity of the identified risks, prevention is a central lever for ensuring the safe and sustainable management of end-of-life lithium-ion batteries. Analyses show that most recorded incidents could have been avoided through better flow organisation, the standardisation of procedures, and enhanced operator training. The objective is not only to reduce the number of accidents but also to establish a genuine culture of prevention at every stage of the value chain, from collection to reuse and recycling.

Operational prevention measures

The first priority concerns the collection and identification of batteries. Feedback from the field shows that many incidents occur at this early stage due to poor sorting practices or limited knowledge of battery types. It is therefore essential to strengthen the training of personnel involved in collection, particularly in waste collection centres and consolidation facilities. Visual identification of lithium-ion batteries, their separation from other waste streams (such as alkaline cells or lead-acid batteries), and the identification of damaged or swollen batteries must become systematic practices. The use of approved, ventilated, and fire-resistant containers, such as those compliant with P911 or LP906 instructions, is also an indispensable baseline measure.

The sorting and dismantling phase represents another critical point. Operations should be carried out in designated, ventilated areas free from any potential ignition sources. Workers must be equipped with appropriate protective gear: insulated gloves, face shields, anti-static clothing, and personal respiratory protection where gas emissions may occur. The use of non-conductive tools and the prior verification of the batteries’ state of charge significantly reduce electrical risks. Similarly, implementing standardised procedures for removing batteries from vehicles or light mobility devices helps to limit hazardous handling and mechanical shocks.

Storage is the phase with the highest risk of fire and thermal runaway. Several good practices should be generalised. The segregation of batteries into isolated clusters helps to limit fire propagation in case of an incident. Storage areas must be equipped with thermal sensors, video surveillance, and automatic fire suppression systems. The materials used (pallets, partitions, coatings) should have adequate fire resistance. It is also recommended to maintain a low state of charge for stored batteries (ideally around 30%) and to regularly monitor humidity and ambient temperature. Safety distances between stacks must be sufficient to prevent the spread of fire through radiant heat.

Regarding transport, compliance with regulations on the transport of dangerous goods (ADR, RID, IMDG, ICAO) remains essential at every stepl. Packaging must be properly labelled, sealed, and designed to withstand shocks and vibrations that occur during transit. The transport of damaged or compromised batteries requires specific authorisation and the use of inert packing materials such as sand, vermiculite, or ceramic granulate to prevent short circuits. End-to-end flow traceability, from the collection point to the final destination, must be ensured through harmonised documentation compatible with the forthcoming European battery passport, which will help standardise tracking practices.

Concerning reuse and second-life applications, stricter oversight is required. The proliferation of reconditioning initiatives, sometimes operating outside any established regulatory framework, has created potentially hazardous situations. It is recommended therefore to standardise methods for assessing the state of health (SoH) of batteries before reuse. Batteries destined for stationary energy storage (BESS) applications must undergo performance and safety tests equivalent to those required for new batteries, particularly regarding thermal propagation and mechanical resistance. The grouping of cells from different origins should be prohibited unless advanced electronic management systems (BMS) ensure proper balancing and electrical compatibility.

Finally, recycling procedures also require reinforced safety measures. Before any mechanical operation such as shredding, crushing, or compaction, batteries must be fully discharged and isolated. Treatment areas should be enclosed and equipped with dedicated gas extraction systems and fine-particle filtration units to limit worker exposure. Liquid effluents and solid residues must be rigorously controlled to prevent environmental contamination. Both hydrometallurgical and pyrometallurgical processes should be governed by specific preventive measures, notably to confine acidic vapours, volatile metals, and any hazardous compounds released during the thermal and chemical treatment phases.

Cross-cutting areas for improvement

Beyond the measures specific to each stage, several cross-cutting recommendations emerge to strengthen prevention throughout the battery value chain.

The first area concerns the enhancement of the regulatory and standardisation framework. Feedback from experience shows that many existing standards fail to cover real end-of-life situations. It is therefore necessary to introduce specific requirements addressing thermal propagation, impact resistance, and module compatibility. New standards should also cover conversion kits and next-generation batteries, such as sodium-ion and lithium-metal, that are still poorly integrated into existing frameworks. Greater harmonisation at the European level is desirable to ensure a consistent approach among Member States, avoid disparities in interpretation and provide clearer guidance to operators.

The second area relates to training and awareness. Operators, maintenance technicians, firefighters, and waste management personnel must be trained in the specific risks associated with lithium-ion batteries. Training modules should include both theoretical aspects (such as thermal runaway mechanisms and battery chemistries) and practical content (safe handling, emergency procedures, and first response to fires). Local authorities and producer responsibility organisations also play an important role in raising public awareness about the safe domestic management of used batteries, particularly regarding sorting and proper deposit at authorised collection points.

The third area concerns research and innovation. The development of early detection sensors for thermal runaway, non-combustible materials, and low-impact recycling processes should be a priority. Real-time monitoring systems (temperature and gas sensors) integrated into storage infrastructures can prevent most fire incidents. Moreover, research on solid or semi-solid electrolytes, which are less flammable, offers promising prospects for intrinsically reducing risks.

The fourth area focuses on traceability and digitalisation. The forthcoming European battery passport represents a major step forward. It will make it possible to track the entire lifecycle of each battery, from manufacturing to recycling, and to share data among manufacturers, treatment operators, and regulatory authorities. For this tool to be fully effective, it must be interoperable with existing management systems and rely on harmonised data formats to enable seamless integration across the supply chain.

Finally, the fifth area addresses intersectoral cooperation. Managing the risks associated with lithium-ion batteries requires close coordination among industry stakeholders, local authorities, regulators, and emergency services. Establishing common protocols, sharing feedback, and developing joint emergency response plans are key factors in controlling crisis situations.

These recommendations reflect a central conclusion: risks related to lithium-ion batteries can only be effectively reduced through a comprehensive approach that combines technology, regulation, training, and cooperation. The challenge lies in implementing local preventive measures, adapted to the operational realities of sites, while maintaining strategic frameworks harmonised at the European level.

Conclusion

The rapid growth of lithium-ion batteries in mobility and energy storage requires a profound transformation of industrial and regulatory practices. The main risks (fires, explosions, toxic emissions, and pollution) are now well identified, but their prevention demands coordinated investment in infrastructure, training, and research. Worker safety, environmental protection, and industrial continuity directly depend on these combined efforts.

The deployment of tools such as the battery passport, improvements in sorting and storage protocols, the harmonisation of standards, and the upskilling of professionals represent tangible and immediately actionable levers. In the medium and long term, technological innovation and cooperation among Member States will make it possible to build a safer, more sustainable, and more competitive European battery sector.

Managing the risks associated with lithium-ion batteries is therefore not merely a safety requirement, it is a cornerstone of the energy transition’s success. Ensuring safety across the entire battery lifecycle, from manufacturing to recycling, means reconciling technological progress with the protection of people and the preservation of the environment.