Reuse of Lithium Iron Phosphate (LiFePO₄) Batteries from a Life Cycle Assessment Perspective: The Second-Life Case Study

Abstract

As of 2035, the European Union has ratified the obligation to register only zero-emission cars, including ultra-low-emission vehicles (ULEVs). In this context, electric mobility fits in, which, however, presents the critical issue of the over-exploitation of critical raw materials (CRMs). An interesting solution to reduce this burden could be the so-called second life, in which batteries that are no longer able to guarantee high performance in vehicles are used for other applications that do not require high performance, such as so-called stationary systems, effectively avoiding new over-exploitation of resources. In this study, therefore, the environmental impacts of second-life lithium iron phosphate (LiFePO₄) batteries are verified using a life cycle perspective, taking a second life project as a case study. The results show how, through the second life, GWP could be reduced by −5.06 × 10¹ kg CO₂ eq/kWh, TEC by −3.79 × 10⁰ kg 1.4 DCB eq/kWh, HNCT by −3.46 × 10⁰ kg 1.4 DCB eq/kWh, −3.88 × 10⁰ m²a crop eq/kWh, and −1.12 × 10¹ kg oil eq/kWh. It is further shown how second life is potentially preferable to other forms of recycling, such as hydrometallurgical and pyrometallurgical recycling, as it shows lower environmental impacts in all impact categories, with environmental benefits of, for example, −1.19 × 10¹ kg CO₂ eq/kWh (compared to hydrometallurgical recycling) and −1.50 × 10¹ kg CO₂ eq/kWh (pyrometallurgical recycling), −3.33 × 10² kg 1.4 DCB eq/kWh (hydrometallurgical), and −3.26 × 10² kg 1.4 DCB eq/kWh (pyrometallurgical), or −3.71 × 10⁰ kg oil eq/kWh (hydrometallurgical) and −4.56 × 10⁰ kg oil eq/kWh (pyrometallurgical). By extending the service life of spent batteries, it may therefore be possible to extract additional value while minimizing emissions and the over-exploitation of resources.

1. Introduction

1.1. Background

According to the International Energy Agency (IEA), the transport sector was responsible for about 8.8 GT CO₂ eq in 2022, 40% of global CO₂ emissions related to the energy sector [1,2]. Transport sector emissions, which have been growing steadily since the 1990s (except the COVID-19 period) (Figure 1), contribute significantly to climate change and its related impacts, such as rising global temperatures, sea-level rise, and extreme weather events [3]. For this, in March 2023, the European Parliament ratified an obligation for the European Union to register only zero-emission cars, including ultra-low-emission vehicles (ULEVs) and vehicles with thermal engines as long as they are fueled with climate-neutral fuels [4]. There could thus be three possible ways forward: biofuels [5], electrofuels (e-fuels) [6], and electric cars [7].

Figure 1. Transportation sector emissions [1].

Figure 1. Transportation sector emissions [1].

Therefore, each of the three systems has its criticalities. The biofuels on which Italy has focused were rejected by the European Commission (EU) (based on a rather ideological approach), as according to the body, they will always have a very large carbon footprint (CF). Although e-fuels are a promising solution for all modes of transport, as they are chemically the same as fossil hydrocarbons [8], and thus without significant investment in either new refueling infrastructures or cars, to date, they are not yet available in roadside petrol stations, and their production is not yet feasible, as they are still very expensive and very energy-intensive [6]. Although it is reasonable to assume that by 2035, the production of e-fuels is unlikely to become simultaneously economical, sustainable, and scalable, car manufacturers are developing business plans well in advance, and most of them have already announced that the combustion engine will be abandoned well before 2035, not least because it would be inconvenient for them to invest in two technologies (electric cars and e-fuels) at the same time, concentrating mostly on the already proven electrification. Many manufacturers are already moving away from petrol and diesel to pure electric, often aiming to make the transition well before 2035. This, therefore, will impose a substantial increase in demand for Lithium-Ion Batteries (LIBs), which will entail two not-insignificant issues, one upstream, and another downstream, although closely related. Regarding the former, electric batteries are mostly composed of Critical Raw Materials (CRMs), i.e., “raw materials (mineral or otherwise) for which there are no viable substitutes with current technologies, on which most consuming countries make their imports dependent, and whose supply is dominated by one or a few manufacturers” [9]. They are notoriously characterized by a cap on production, declining reserves, rising extraction costs, and heavy dependence on a few countries [10], and are critical to Europe’s green and digital ambitions, which is why they are of significant economic importance, and their insecurity of supply may hinder the development and implementation of new technologies [11]. But another significant challenge facing batteries also relates to the downstream process of their life, i.e., disposal [12]. In particular, according to the American Chemical Society, the complex structure of batteries requires manual disassembly and thus high labor costs [13], which would only make sense in countries where labor costs are low. But recycling also has environmental costs, including transport, preparation, and high energy consumption for battery combustion and calcination [14] as well as reagents and water purification [15]. Therefore, due to the objective processing difficulties, recycling LIB batteries can sometimes be inconvenient and costly, which is why, although European legislation tends to the opposite direction [16], most LIB batteries at the end of their life are discharged into landfills, contaminating the earth [17], exerting a huge environmental impact, and accelerating the depletion of mineral reserves [13]. In this context, an interesting and potentially effective solution could be the so-called ‘second life’ [18]. LIBs, after about 10 years of use in cars, are no longer able to meet the performance requirements of vehicles due to the normal degradation caused by obsolescence and the various charge and discharge cycles to which they are subjected, heading toward an end-of-life phase. However, the remaining capacity and lifetime may still be suitable for other applications that do not require high performance, such as stationary systems, thus enabling their reuse [19]. Given that LIB retirement occurs when the effective capacity falls below 70% of the nominal capacity, this means that the battery, although degraded by use, still has a residual capacity that could make it suitable for other stationary applications, thus avoiding disposal in landfills and considering the batteries as secondary raw materials. In this sense, batteries considered end-of-life are used for a purpose requiring less wear and tear than the one for which they were put on the market and not as waste.

1.2. Aim of the Study

In light of the reuse potential of lithium-ion batteries in second-life applications, it might be important to verify their sustainability through a life cycle assessment (LCA) [20,21]. In the context of LIBs, this assessment could be particularly relevant to investigate how the need to extract and process limited raw materials could be reduced and to quantify the resource savings achieved through second-life use. But also, to understand how, by extending the life of LIBs, the emissions associated with their production could be offset. Or to assess how promoting second-life applications for LIBs could significantly reduce the generation of hazardous waste as these batteries could continue to provide value, albeit at a reduced performance level. In this sense, comprehensive LCAs can inform policy decisions and regulations regarding the reuse, recycling, and sourcing of sustainable battery materials. Therefore, in light of the above, the objective of this research is to verify through LCA the potential environmental benefits of reusing second-life batteries for stationary energy storage. To this end, a project carried out by an Italian company (made anonymous for privacy issues) was chosen as a case study to be launched in 2025. This project uses electric vehicle batteries as a source of energy through their interconnection and storage within a stationary facility on an island in Morocco. This system is integrated with the town’s electrical system to avoid load-shedding events and thus ensure continuity of grid service to the local population in case of instability due to peak demand. This project could demonstrate how, in line with the principles of Open Innovation, solutions can be found for end-of-life management of equipment essential for energy transition and decarbonization, such as batteries. In addition to being a practical example of extending the life of electric vehicle batteries, this project could show an additional innovative component: in effect, when each battery is removed from the electric vehicle, it is placed directly in the storage system, exactly as it was in the vehicle, without disassembling it into individual cells before being installed in the storage system, making the whole process simpler, safer, and cheaper.

2. Materials and Methods

2.1. Case Study Description

This case study is the result of a collaboration between three companies, one of which is Nissan (which provided the batteries). The other two are, respectively, a company that develops storage systems and system integrators and a company that owns a stationary plant, the purpose of which is to increase the stability of the electric grid by using discarded batteries from Nissan electric cars. The plant involves the use of 68 Nissan batteries, including 38 decommissioned and 30 new ones. The facility has a maximum capacity of 5 MW and a maximum stored energy of 1.9 MWh, and in the event of a power plant disconnection from the grid, the storage facility can supply power to the city grid for 15 min, enough time to restart the grid without interruption to the end user. This case study was chosen mainly for two reasons:

• It could be a useful and representative example of sustainable power generation and circular economy. In fact, since through this project, it was possible to reuse materials at the end of their life, create value in a sustainable way as well as increase the reliability of the entire power grid, it could not represent just a pilot project for the future, but also a real expression of circular economy in all its forms, and therefore worthy of attention.
• The availability of information, accessibility of data, and cooperation of the company allowed the study to be conducted in an acceptable time frame.

This case study may offer a chance to assess the environmental performance brought about by the reuse of electric batteries from a second-life perspective, and this approach was considered attractive because of its potential for reduced impacts and reduced reliance on critical raw materials. However, it is important to note that while this case study could offer insightful information, its selection is not meant to serve as a comprehensive example of second-life batteries. Furthermore, the case study represents a specific use system and is not necessarily representative of all specific uses of second-life batteries globally.

2.2. Life Cycle Assessment

The main steps of the LCA of this study are based on the ISO 14040:2006 [20] and ISO 14044:2006 [21]. The functional unit (FU) and methodological steps are summarized in

Table 1. Summary of LCA phases.

	1st Life	2nd Life
(1) GOAL AND SCOPE DEFINITION
Functional Unit	1 kWh	1 kWh
System boundaries	From cradle to grave	From gate to grave
Life Cycle Phases	Transportation of raw materials, manufacturing, shipping, use	Shipping, use
(2) LIFE CYCLE INVENTORY (LCI)
Data quality	Primary data were obtained through interviews with the company managers, secondary data from gray literature, and scientific literature
Database	Ecoinvent v3.8
(3) LIFE CYCLE IMPACT ASSESSMENT (LCIA)
Calculation method	Recipe 2016 MidPoint (H)
Impact categories	Atmospheric effects: Global Warming Potential (GWP), Stratospheric Ozone Depletion (SOD), Ionizing Radiation (IR), Ozone Formation-Human Health (OFHH), Fine Particulate Matter Formation (FPMP), Ozone Formation-Terrestrial Ecotoxicity (OFTE), Terrestrial Acidification (TAP) Eutrophication: Freshwater Eutrophication (FEP) and Marine Eutrophication (MEP) Toxicity: Terrestrial Ecotoxicity (TEC), Freshwater Ecotoxicity (FEC), Marine Ecotoxicity (MEC), Human Carcinogenic Toxicity (HCT), Human Non-Carcinogenic Toxicity (HNCT) Abiotic Resources: Land Use (LU), Mineral Resource Scarcity (MRS), Fossil Resource Scarcity (FRS), and Water Consumption (WC)
Software	Simapro 9.5.

and detailed in the following paragraphs.

2.2.1. Goal and Scope Definition

The goal of this LCA is to verify the environmental impacts of a reused second-life battery within the stationary facility, compared to a first-life battery, to understand the environmental benefits of second life. The study could be useful for companies, stakeholders, and the wider public from a corporate social responsibility perspective, as it could provide insights into the role of storage in a global economic context with a particular focus on second life to guide business decisions toward conscious choices. The estimated useful life of a first-life battery is around fifteen years, while second-life batteries have a useful life of around five years [22]. The analysis was conducted using a cradle-to-grave approach, i.e., undergoing all phases of the battery life cycle, not considering the installation phase due to the lack of some data. A lithium iron phosphate (LiFePO₄) battery was considered the component of one of the electrodes, unlike most batteries in mobile phones, laptops, and electric cars, where these electrodes consist of a mixture of lithium–cobalt. The inventory data, shown in Tables S1 and S2, refer to 1 single lithium iron phosphate battery from a Nissan Leaf, the production and assembly of which takes place in China. Then, as a functional unit, the data were normalized to 1 kWh of energy, consistent with other authors, such as Philippot et al. (2022) [23] and Kotak et al. (2021) [24], who state how 1 kWh should be the FU that should be used in all LCAs if comprehensive comparisons are to be expected, and finally, Porzio and Scown (2021) [25], who recommend, for the future comparability, standardizing the usage of kg of battery mass as a functional unit in LCAs to 1 kWh of battery capacity. The choice of 1 kWh as FU is also aligned with the Advanced Researchable and Lithium Batteries Association [26]. The main differences between first and second-life batteries are related to two factors:

• In the context of second life, the production phase is excluded, specifically on the assumption that the batteries are already on the market and have a different initial use than that which will be carried out within the stationary plant.
• The transport phase will also be different, as the batteries will no longer be acquired from the initial manufacturer (China) but purchased on the European market.

2.2.2. Life Cycle Inventory

The data used within this study are primary and were collected following several meetings with the company’s managers, thanks to the collaboration with Nissan, who provided all available information for the inventory. Then, correspondence was maintained by e-mail with the companies involved to discuss and establish the most relevant processes. In contrast, the background data derives from the integrated Ecoinvent 3.5 database [27] and the SimaPro 9.5 software [28]. Then, the utilization phase can be divided into two parts. The first life involves the battery being used in electric vehicles, while the second life involves the battery being withdrawn and used within a stationary installation. As for the transport data, a meticulous and rigorous analysis of the suppliers was conducted to trace the path taken by the CRMs before the battery leaves the production plant. The various steps are detailed in the following subsections.

(1)

Production

LiFePO₄ battery is manufactured in China and produced by Contemporary Amperex Technology Co. Limited (CATL), Ningde, China, a company that produces lithium-ion batteries for energy storage systems and electric vehicles, whose production plant is in the city of Ningde (Fujian). In 2021, with a share of 32.6% globally and 52% domestically [29], CATL was the world’s leading battery manufacturer, from which Nissan also sources its batteries. The battery cell is made up of five macro-components (anode, cathode, electrolyte, separator, and cell container), each, in turn, made up of a certain type of material expressed in kg (Table S1). The total weight of the battery is approximately 610 kg (for a capacity of 110 kWh), of which a significant portion is represented by raw materials (Table S1) that, according to the latest update and summary carried out in March 2023 by the European Union [30] are considered critical: Lithium, Graphite, Copper, Bauxite (for aluminum production), Phosphate Rocks (for phosphate synthesis), and Coal Coke (for steel production). Regarding lithium, although it mainly comes from the ‘Lithium Triangle’ (Chile, Argentina, and Bolivia) (70% of global reserves) and Australia [31], China possesses most of the world’s refining capacity and is also the first importer and consumer of lithium worldwide, as well as a large producer of lithium carbonate and lithium hydroxide, mostly from ore concentrates (spodumene), imported from Australia [32,33,34]. Therefore, it was assumed that China sources from Australia. Before arriving at the CATL facility, where the battery parts are assembled, the lithium, sourced from Australia, undergoes a long refining route. Specifically, it travels from Australia to the port of Shanghai (6145 km as the crow flies) via cargo ships. From there, it is shipped and processed by other Chinese suppliers. In particular, it was assumed that the production of electrodes and other materials was carried out by Zhangjiagang Guotai Huarong New Chemical Materials Co., Suzhou, China, the leading electrode producer in China and one of the top three suppliers of electrolytes for lithium batteries in the world [35], traveling a further 170 km (from the port of Shanghai to the Zhangjiagang Guotai Huarong facility) and 845 km (from the Zhangjiagang Guotai Huarong facility to the CATL plant) in both cases by truck, for a total journey of 6160 km. Regarding Bauxite for aluminum production, it comes mainly from Malaysia, Guinea, and Australia [30,33], which possess nearly 65% of global resources, while Alumina comes mainly from China, which accounts for 47% of global production, making it the first Aluminum producer worldwide (52% of the global market) [30]. Therefore, it was assumed that China exports Bauxite from Malaysia, a choice motivated by both cost and proximity factors, while Alumina is produced domestically. To date, research on CATL’s major suppliers [36], also considering its and their ESGs, shows how it sources aluminum from Jiangsu Dingsheng New Materials Joint-Stock, Xuzhou, China [37], assuming how the latter, in turn, sources Bauxite from Malaysia. Therefore, the alumina component of the battery travels at least 6038 km, including about 5000 km via cargo ship from Malaysia to the port of Shanghai [38], the closest to the Jiangsu Dingsheng New Materials Joint-Stock site and to which it travels 209 km via truck, and then travels another 829 km via truck from Jiangsu Dingsheng Chemical Co., Ltd., Zhenjiang, China, to the CATL facility. Data on alumina production are not known. Regarding phosphate rock, it is the main anthropogenic source of phosphorus, and the main producer is China with 87% of the world’s production [39], most of whose production capacity is used internally. Therefore, it is assumed that China produced the entire amount needed for battery production internally. However, it is not known from which supplier CATL sources phosphate. For Natural Graphite, China is the world’s largest producer and exporter, along with Australia, as well as the leading producer of coking coal (precursor to Graphite) globally [30]. CATL for artificial graphite anode materials mainly sources from Jiangxi Zichen, a wholly owned subsidiary of Putailai, a leading company in lithium battery anode materials, whose distance to CATL’s production site is about 825 km, traveled via truck. Regarding Copper, although the main producers are Chile and the Democratic Republic of Congo, China still has a good mining capacity [33], and thus domestic production was considered.

Specifically, it was assumed that CATL for copper has a partnership with Guangdong Jiayuan Technology, Meizhou, China, [40], the world’s leading global copper supplier, whose distance to CATL’s production site is 571 km traveled by truck. It is important to note that China’s specific sources of copper can vary over time and depend on factors such as market conditions, trade agreements, and domestic production capacity. Therefore, there is no single copper quarry exclusively related to battery production in China, especially Guangdong, which is why the transportation phase from quarry to site has been excluded. For Dimethyl Carbonate and Ethylene carbonate currently no data were found available about their specific origin, which is why it was assumed that they come from Shandong Shida Shenghua Chemical Group Co., Dongying, China, the first player in China and the third globally in the dimethyl carbonate and basic organic chemical markets (ethylene carbonate, ethyl methyl carbonate, propylene carbonate, lithium hexafluorophosphate, and special additives for electrolytes) [41], whose distance is 1481 km, traveled via truck. For Polyolefin, Synthetic rubber, Glass fiber, and Silicon, source data could not be found. For transportation calculation, TKM (Tonne-Km) was used as the unit of measurement, based on Equation (1).

$$\mathrm{T}\mathrm{K}\mathrm{M}=\sum (\varnothing i\times \frac{\delta }{1000})$$

(1)

The following variables are used:

• ∅i Is the distance in km as the crow flies of commodity i from place x to place y.
• δ Is the weight in kg of the material being transported.

In LCA studies, it could be difficult to find transportation data, given the obvious complexity of supply chains and the complete route that raw materials take. For this reason, it is important to clarify some of the limitations of this study, both concerning the source of the data and the various modes of transportation, which led to making some assumptions. First, about the source of transportation data, within this study, the various routes, as well as all transportation data, as they are not always available for all inputs, were inferred from websites and gray literature searches, such as CATL providers and their ESGs. However, the documentary value of the gray literature used remains enormous, if for no other reason than the indications it provides about the presence of a given phenomenon. Thus, considering the objective difficulty of finding some route data, sometimes not collected, the issues are most likely underestimated. However, this choice is still consistent with the objective of this research, which is not so much to quantify emissions punctually but based on the available data to shed light on the long supply chain of batteries and the long distance that CRMs for batteries production must travel, thus framing the whole long system behind their production and emphasizing the importance and environmental impact of transportation. As for the transportation of various commodities within China, however, a truck mode of transportation was chosen to be considered within this study. This choice is primarily motivated by the fact that, as said by a recent report by the International Council on Clean Transportation (ICCT), although railways have been the leader in China’s freight transportation system for years, trucks currently account for about 50% of freight activity and nearly 80% of freight tonnage in 2019) [42]. Recently, however, the Chinese government has accelerated the expansion of the rail network, investing about CNY 3.5 trillion [43], growing rail freight at an annual rate of +6.9% between 2015 and 2019, yet still accounting for 9.5% of total freight transport in China [43]. Lastly, it is important to remember that while China’s battery industry is multifaceted and generally relies on a diverse network of suppliers of electrolytic materials, cathodes, and other essential components, for the scope of this study and due to data availability constraints, in our calculations, for each material, it has been assumed how CATL sourced from a single supplier per material. It is essential to recognize that, in reality, battery production in China involves a multitude of suppliers and a much more complex supply chain, but to move backward punctually through the entire supply chain and identify each supplier is not reasonably feasible. The manufacturing phase was also excluded for the second life process.

(2)

Shipping

LiFePO₄ batteries belong to IATA*DGR9 class and UN Category 9 and are therefore considered dangerous goods if transported by air because if exposed to certain uncontrolled environmental conditions or handled incorrectly during transportation, they become thermally and electrically unstable, which is why they may ignite [11]. Therefore, once production is finished from the Ningde production site, the battery travels via truck to the port of Shanghai, covering about 700 km, from where it is shipped by cargo ships to the ports of Genoa, Livorno, or Cagliari (Italy), a distance of 9000–13,000 km. The ships reach European ports in about 35–40 days from the date of departure. Finally, the batteries are delivered to Morocco, again via cargo ship, for a distance of 1340 km. In all cases, the distance was calculated as the crow flies, considering Google Maps coordinates, mainly because of the difficulty in finding accurate data on the route taken by the trucks and ships. In the case of the second life process, transportation is calculated only for the final stage, thus, from Italy to Morocco.

(3)

Installation

Once it arrives at the stationary site, the battery is installed inside, for the construction of which 3.5 mW is needed: 19.5 m² of soil, 7.8 m³ of concrete, and 550 kg of steel for 180 days. Energy, water, and fuel are unknown. Therefore, despite being referred to as a matter of completeness, this phase was not considered in this research due to the unavailability of some data as well as the reduced environmental contribution caused by the multi-year useful life and depreciation of capital assets [44,45].

(4)

Use

The fourth step relates to use and maintenance over the lifetime of the batteries. The number of cycles a single battery can perform over its lifetime was calculated and estimated, considering just one charge and discharge cycle per day. The Battery Energy Storage System (BESS) round-trip efficiency of 85% represents the percentage of stored electricity that is then recovered (

Table 2. Main characteristics of LiFePO₄ battery during the use phase.

Characteristics	Amount	Unit
Lifetime	15	years
Cycle per lifetime	5475	n cycles
BEES installed power	20	MW
BEES installed energy capacity	40	MWh
BEES round-trip efficiency	85	%
BESS one way efficiency	92	%
Depth of discharge	80	%
Delivered energy during the lifetime	161,526	MWh
Electricity losses (discharge)	13,674
Electricity losses (charge)	14,831
Electricity losses (total)	28,505

).

The less energy lost during storage, the higher the round-trip efficiency. Depth of discharge is intended to tell battery users how much energy they can safely use without compromising battery life. For example, considering a battery with a depth of discharge of 80% means that only 80% of the total rated capacity of the battery can be used. Or, considering a battery with a capacity of 500 ampere-hours, this means that there will only be 400 ampere-hours with which to work at a depth of discharge of 80%. Delivered energy during lifetime represents the maximum amount of energy deliverable during the estimated 15-year lifetime of 161,526 MWh. The last two items related to electricity losses represent the energy lost during the discharge and charge of the battery.

2.2.3. Life Cycle Impact Assessment

To ensure the credibility of the findings of this research, the ReCiPe 2016 MidPoint (I) methodology (I indicate the short-term individualist perspective, according to an optimistic view that technology can avoid many problems in the future) was followed for this case study. SimaPro 9.5 software was used [29], and the 18 impact categories were grouped into four macro areas.

• Atmospheric Effects: Global Warming Potential (GWP), Stratospheric Ozone Depletion (SOD), Ionizing radiation (IR), Ozone Formation-Human Health (OFHH), Fine Particulate Matter Formation (FPMP), Ozone formation-Terrestrial ecosystems (OFTE), and Terrestrial acidification Potential (TAP).
• Eutrophication: Freshwater Eutrophication Potential (FEP) and Marine Eutrophication Potential (MEP).
• Toxicity: Terrestrial Ecotoxicity (TEC), Freshwater Ecotoxicity (FEC), Marine Ecotoxicity (MEC), Human Carcinogenic Toxicity (HCT) and Human Non-Carcinogenic Toxicity (HNCT).
• Abiotic Resources: Land Use (LU), Mineral Resources Scarcity (MRS), Fossil Resources Scarcity (FRS) and Water Consumption (WC).

In selecting impact categories, several variables, such as stakeholder interests, scientific importance, and environmental context, were considered. Having eighteen impact categories [46] (compared to 16 in the ILCD 2011 Midpoint, 15 in the IMPACT 2002 +, 11 in the CML-IA Baseline, and 9 in the TRACI), the ReCiPe 2016 MidPoint (I) was preferred over other calculation methods such as the ILCD 2011 [47], CML 2001 [48] or TRACI [49] because it can provide more detailed, accurate, and comprehensive results on the environmental impacts of a product or process.

2.3. Scenario Analysis

After that, the second-life process was compared with two additional end-of-life possibilities for batteries, thus constructing two alternative scenarios, considering the two currently best-known industrialized recycling processes [50], namely pyrometallurgical recycling [13] (Scenario A) and hydrometallurgical recycling [51] (Scenario B) (Figure 2). Of the two, the currently most scalable process is pyrometallurgical recycling, which involves melting the battery in a system at high temperatures (1600–1700 °C) to obtain purified metal alloys [51,52,53]. Hydrometallurgical recycling, on the other hand, mainly involves the leaching of cathode material from the dismantling and separation stage through the use of aqueous solutions to dissolve precious metals [51,52,53]. Essentially, the goal of this scenario analysis is to show the possible benefits of reuse (thus giving spent batteries a second use to extend their service life) rather than recycling (with the precious materials present being recycled and fed back into the value chain). Data on the environmental impacts of the process of extracting precious metals by pyro and hydrometallurgy, referring to 1 kWh of rated capacity, come from Kallitsis et al. (2022) [54].

Figure 2. Overview of the two recycling processes considered [52,53].

Figure 2. Overview of the two recycling processes considered [52,53].

3. Results and Discussion

3.1. Life Cycle Assessment

Regarding the first-life process, the LCA results are shown in

Table 3. Life cycle impact assessment results.

Component		Anode		Battery Container		Cathode		Cell Container		Cooling System		Electrolyte		Module Container		Separator		Transportation		Total
Categories/Unit		Value	%	Value	%	Value	%	Value	%	Value	%	Value	%	Value	%	Value	%	Value	%	Value	%
Atmospheric
GWP	kg CO2 eq	5.65 × 100	11%	1.49 × 100	3%	9.49 × 100	18%	1.27 × 101	25%	2.93 × 100	6%	6.20 × 100	12%	8.94 × 100	17%	4.04 × 10−1	1%	3.60 × 100	7%	5.14 × 101	100%
SOD	kg CFC11 eq	2.24 × 10−6	18%	3.06 × 10−7	3%	1.67 × 10−6	14%	2.15 × 10−6	18%	7.24 × 10−7	6%	1.65 × 10−6	14%	2.84 × 10−6	23%	3.92 × 10−8	1%	5.47 × 10−7	4%	1.22 × 10−5	100%
IR	kBq Co-60 eq	5.97 × 10−2	35%	2.97 × 10−3	2%	1.91 × 10−2	11%	2.16 × 10−2	13%	7.75 × 10−3	5%	3.04 × 10−2	18%	2.30 × 10−2	13%	5.39 × 10−4	1%	6.03 × 10−3	4%	1.71 × 10−1	100%
OFHH	kg NOx eq	1.91 × 10−2	12%	4.17 × 10−3	3%	2.27 × 10−2	14%	3.15 × 10−2	19%	1.17 × 10−2	7%	1.39 × 10−2	8%	3.50 × 10−2	21%	6.18 × 10−4	1%	2.69 × 10−2	16%	1.66 × 10−1	100%
FPMP	kg PM2.5 eq	5.33 × 10−3	12%	1.06 × 10−3	3%	5.78 × 10−3	14%	7.37 × 10−3	19%	2.04 × 10−3	7%	2.57 × 10−3	8%	9.70 × 10−3	21%	9.34 × 10−5	1%	9.82 × 10−5	16%	3.40 × 10−2	100%
OFTE	kg NOx eq	1.92 × 10−2	12%	4.18 × 10−3	3%	2.27 × 10−2	14%	3.15 × 10−2	19%	1.17 × 10−2	7%	1.40 × 10−2	8%	3.51 × 10−2	21%	6.20 × 10−4	1%	2.70 × 10−2	16%	1.66 × 10−1	100%
TAP	kg SO2 eq	3.84 × 10−2	15%	6.52 × 10−3	3%	3.97 × 10−2	16%	5.09 × 10−2	20%	1.52 × 10−2	6%	3.38 × 10−2	13%	5.17 × 10−2	20%	8.44 × 10−4	1%	1.85 × 10−2	7%	2.55 × 10−1	100%
Eutrophication
FEP	kg P eq	5.20 × 10−4	19%	7.36 × 10−5	3%	3.45 × 10−4	13%	4.30 × 10−4	16%	1.36 × 10−4	5%	2.93 × 10−4	11%	8.53 × 10−4	31%	7.86 × 10−6	1%	6.13 × 10−5	2%	2.72 × 10−3	100%
MEP	kg N eq	2.16 × 10−4	20%	2.04 × 10−5	2%	7.64 × 10−5	7%	9.15 × 10−5	9%	2.57 × 10−5	2%	4.33 × 10−4	40%	2.08 × 10−4	19%	1.46 × 10−6	1%	1.14 × 10−6	1%	1.07 × 10−3	100%
Toxicity
TEC	kg 1,4-DCB	5.36 × 10−1	14%	7.70 × 10−2	2%	4.57 × 10−1	12%	5.80 × 10−1	15%	1.87 × 10−1	5%	1.19 × 100	31%	6.00 × 10−1	16%	7.14 × 10−3	1%	2.32 × 10−1	6%	3.86 × 100	100%
FEC		2.12 × 10−4	8%	9.20 × 10−5	3%	4.79 × 10−4	18%	6.18 × 10−4	23%	1.71 × 10−4	6%	3.03 × 10−4	11%	7.94 × 10−4	29%	4.35 × 10−6	1%	2.37 × 10−5	1%	2.70 × 10−3	100%
MEC		7.17 × 10−4	16%	1.33 × 10−4	3%	6.70 × 10−4	15%	8.55 × 10−4	19%	2.49 × 10−4	6%	2.98 × 10−4	7%	1.37 × 10−3	31%	6.08 × 10−6	1%	9.87 × 10−5	2%	4.40 × 10−3	100%
HCT		2.13 × 10−3	16%	2.47 × 10−4	2%	1.46 × 10−3	11%	2.05 × 10−3	16%	1.05 × 10−3	8%	1.66 × 10−3	13%	1.55 × 10−3	12%	2.16 × 10−5	1%	2.75 × 10−3	21%	1.29 × 10−2	100%
HNCT		5.65 × 10−2	2%	1.22 × 10−2	4%	1.88 × 10−2	1%	2.13 × 10−2	1%	1.28 × 10−2	0%	4.97 × 10−2	1%	3.14 × 100	90%	9.58 × 10−4	1%	5.44 × 10−2	2%	3.48 × 100	100%
Abiotic resources
LU	m2a crop eq	4.71 × 10−1	12%	1.11 × 10−1	3%	6.77 × 10−1	17%	8.23 × 10−1	21%	2.31 × 10−1	6%	5.92 × 10−1	15%	9.51 × 10−1	24%	8.28 × 10−3	1%	3.00 × 10−2	1%	3.89 × 100	100%
MRS	kg Cu eq	5.21 × 10−1	34%	3.41 × 10−2	2%	9.49 × 10−2	6%	9.38 × 10−2	6%	2.49 × 10−2	2%	1.02 × 10−1	7%	6.51 × 10−1	43%	4.34 × 10−4	1%	3.40 × 10−4	1%	1.52 × 100	100%
FRS	kg oil eq	1.67 × 100	15%	2.88 × 10−1	3%	1.84 × 100	16%	2.41 × 100	21%	7.86 × 10−1	7%	1.68 × 100	15%	1.79 × 100	16%	2.26 × 10−1	1%	7.28 × 10−1	6%	1.14 × 101	100%
WC	m3	3.09 × 10−1	42%	1.15 × 10−2	2%	8.13 × 10−2	11%	7.16 × 10−2	10%	4.33 × 10−2	6%	9.11 × 10−2	12%	1.21 × 10−1	16%	3.25 × 10−3	1%	5.34 × 10−4	0%	7.32 × 10−1	100%

. The most significant impacts are attributable to, for example, GWP, TEC, HNCT, LU, MRS, and FRS. Specifically, about 5.14 × 10¹ kg CO₂ eq/kWh, 3.86 × 10⁰ kg 1.4 DCB eq/kWh, 3.48 × 10⁰ kg 1.4 DCB eq/kWh, 3.89 × 10⁰ m²a crop eq/kWh, 1.52 × 10⁰ kg Cu eq/kWh, and 1.14 × 10¹ kg oil eq/kWh. The largest impacts are mainly attributable to the module container, which, in 11 impact categories, appears to have the largest weight in percentage terms (e.g., 90% for HNCT, 43% for MRS, 31% for MEC, 31% for FEP, 24% for LU, 23% for SOD, 21% for OFHH, FPMP, and OFTE, and 20% for TAP). This is mainly due to impacts related to aluminum, steel, and copper production. In particular, it is estimated that steel production, which generates globally about 145 billion tons of wastewater per year (19 tons/per capita) [55], generates emissions of arsenic, mercury lead, polychlorinated dibenzo-p-dioxins, cyanide, polychlorinated dibenzofurans, and polychlorinated biphenyls (PCBs) classified as polyhalogenated aromatic hydrocarbons (PHAHs) and is thus responsible for human toxicity and poisoning and ecosystem toxicity.

It should also be mentioned that China’s steel industry, which accounts for nearly 50% of the world’s total crude steel supply, is inefficient because most of China’s large- and medium-sized steel mills were born in the 1980s, and thus the efficiency of their utilization is relatively low because of obsolete technologies [56]. However, since China is the largest producer of almost all kinds of basic consumer and industrial goods, as the most influential country, it should instead take responsibility for further improving the utilization efficiency and management level of its processing industries. But steel production is also related to the expansion of mines and the expansion of plantations for coal production, which generate a vast change in land use [57]. Therefore, the major impacts could be explained, for example, by this motivation. On the other hand, as far as GWP is concerned, a large part of the impacts are due to the production of aluminum for the cell container since the extraction of bauxite, and its transformation into aluminum, in addition to devastating vast areas of ancient forests, relying on powerful hydroelectric dams that often flood the lands of indigenous communities, is energy intensive (it is estimated that the production of one ton of aluminum requires 15 MWh of electricity, equal to that used by a family of two in five years) [58]. Also of no small importance are the impacts related to the long-distance transportation process of the various critical raw materials. For example, from Table 3, it can be seen that the transportation phase affects most significantly the atmospheric categories, including GWP and TAP (7% for both), OFHH, FPMP, OFTE (16% in all three cases), and toxicity category HCT (21%). The uneven geographic concentration of critical raw materials used in LiFePO₄ battery production, such as Lithium, Bauxite, and Phosphate Rock, causes long travel and long supply chains for their processing and refining. The logistics of CRMs are thus based on a very intricate network based on long distances, which are then reflected in the overall environmental impacts of, for example, 3.60 × 10⁰ kg CO₂ eq/kWh. It emerges then how the selection of suppliers, locations, and production processes can have a great influence. In contrast, through a second-life reuse pathway, as shown in this case study, emerges how these environmental impacts could be significantly reduced, resulting in a lower environmental burden in all 18 impact categories (

Table 4. Life Cycle impact assessment results: 1st life vs. 2nd life.

Impact Categories	Unit	1st Life	2nd Life	Difference
Atmospheric
Global warming	kg CO2 eq	5.14 × 101	8.16 × 10−1	−5.06 × 101
Stratospheric ozone depletion	kg CFC11 eq	1.22 × 10−5	2.60 × 10−7	−1.19 × 10−5
Ionizing radiation	kBq Co-60 eq	1.71 × 10−1	2.92 × 10−3	−1.68 × 10−1
Ozone formation, Human health	kg NOx eq	1.66 × 10−1	7.69 × 10−3	−1.58 × 10−1
Fine particulate matter formation	kg PM2.5 eq	3.40 × 10−2	4.45 × 10−5	−3.40 × 10−2
Ozone formation, Terrestrial ecosystems	kg NOx eq	1.66 × 10−1	7.74 × 10−3	−1.58 × 10−1
Terrestrial acidification	kg SO2 eq	2.55 × 10−1	3.75 × 10−3	−2.52 × 10−1
Eutrophication
Freshwater eutrophication	kg P eq	2.72 × 10−3	3.01 × 10−5	−2.69 × 10−3
Marine eutrophication	kg N eq	1.07 × 10−3	4.12 × 10−7	−1.07 × 10−3
Toxicity
Terrestrial ecotoxicity	kg 1.4 DCB	3.86 × 100	6.77 × 10−2	−3.79 × 100
Freshwater ecotoxicity		2.70 × 10−3	1.12 × 10−5	−2.69 × 10−3
Marine ecotoxicity		4.40 × 10−3	4.54 × 10−5	−4.35 × 10−3
Human carcinogenic toxicity		1.29 × 10−2	1.21 × 10−3	−1.17 × 10−2
Human non-carcinogenic toxicity		3.48 × 100	1.80 × 10−2	−3.46 × 100
Abiotic resources
Land use	m2a crop eq	3.89 × 100	1.03 × 10−2	−3.88 × 100
Mineral resource scarcity	kg Cu eq	1.52 × 100	1.66 × 10−4	−1.52 × 100
Fossil resource scarcity	kg oil eq	1.14 × 101	2.54 × 10−1	−1.12 × 101
Water consumption	m3	7.32 × 101	2.59 × 10−4	−7.32 × 10−1

), since the second-life pathway in the stationary plant only has to deal with the transport phase from the decommissioning site to Morocco. Impacts for first life are greater than impacts for second life, averaging 929 times (ranging from a minimum of 10.66 times for HCT to a maximum of 9157 times for MRS). For example, GWP could be reduced by −5.06 × 10¹ kg CO₂ eq/kWh, TEC by −3.79 × 10⁰ kg 1.4-DCB eq/kWh, HNCT by −3.46 × 10⁰ kg 1.4-DCB eq/kWh, −3.88 × 10⁰ m²a crop eq/kWh, and −1.12 × 10¹ kg oil eq/kWh. Considering the GWP, the GHG emissions of the reuse scenario are 8.16 × 10⁻¹ kg CO₂ eq/kWh, higher than, for example, the 2.20 × 10⁻¹ kg CO₂ eq/kWh of Philippot et al. (2022) [23] and the 2.25 × 10⁻¹ kg CO₂ eq/kWh of Ahmadi et al. (2017) [59], reported on similar second-life applications of LiFePO₄ batteries. However, the variability in results could be attributable to multiple factors, including, for example, the distance traveled, the means of transportation used as well as the reference electricity mix. Verifying our results and comparing them with those of other studies could be difficult, however. This is for several reasons, including the lack of agreement in the field of LCA on how to analyze the environmental impact of batteries and how to report the results, as a wide variety of system boundaries and different methodological choices are used in LCA studies [25], but also, for example, because of the different capacities and masses of battery packs, which inevitably affect FU normalization. However, the results of our study could still contribute to expanding the body of scientific literature related to LCA assessments of second-life batteries, and although it may seem obvious, they show that through a reuse pathway within a stationary facility, environmental impacts can still be reduced compared to first-life batteries.

Indeed, this is consistent with the findings of other authors, including, Ahmadi et al. (2017) [59]; Ahmati et al. (2014) [60]; Wilson et al. (2021) [61]; and Philippot et al. (2022) [23], in which lower environmental impacts are shown for second-life battery applications. Via second-life applications, the material demand per kWh for new batteries could be reduced, offsetting future demand and decreasing long-term extraction.

3.2. Scenario Analysis

Scenario analysis results, referring to 1 kWh of nominal battery pack capacity, are shown in Figure 3. It is shown that both processes (Scenario A and Scenario B) show higher values than the second-life process. Both scenarios exhibit high energy, waste, and reagent consumption, as also recently noted by Milian et al. (2024) [50], which are then reflected in the less-than-negligible environmental impacts. In fact, between the two processes, second life shows lower environmental impacts in 18 out of 18 impact categories, with environmental benefits, for example, of −1.19 × 10¹ kg CO₂ eq/kWh (scenario A) and −1.50 × 10¹ kg CO₂ eq/kWh (scenario B), −3.33 × 10² kg 1.4 DCB eq/kWh (scenario A) and −3.26 × 10² kg 1.4 DCB eq/kWh (scenario B) or −3.71 × 10⁰ kg oil eq/kWh (scenario A) and −4.56 × 10⁰ kg oil eq/kWh (scenario B). Therefore, through these LCA results, it is shown that current recycling technologies are still far from environmental maturity because of the complexity of batteries and the variability and chemistry of components and processes used. Our findings are consistent with the relevant scientific literature, including, for example, Milian et al. (2024) [50]; Dobò et al. (2023) [51]; and Marchese et al. (2024) [62], who show that the two processes best known to industries are effective but still unsustainable because of their high environmental impact. In contrast, reusing batteries in stationary plants could extend battery life before the materials are recycled at the end of the life cycle.

Figure 3. Results of the scenario analysis.

Figure 3. Results of the scenario analysis.

Through this, the second-life application could then represent smart management of used batteries and battery materials to ensure that electric vehicles and their batteries are more sustainable along a life cycle perspective, helping to address the coming wave of used batteries [63]. Therefore, a second-life pathway as a stationary facility could be considered as a more sustainable form of reuse for the recovery of a spent battery that can support sustainable recycling processes, also consistent with the waste management hierarchy, which shows that remanufacturing and reuse are preferable to recycling. Indeed, although there are different methodologies for recovering components and precious metals in lithium batteries, some of which have been recently applied and discovered, each has disadvantages (

Table 5. Overview of some LIB recycling technologies.

Tipology	Characteristics	Disadvantages	Ref.
Pyrometallurgical	After being crushed and separated, the graphite and active cathode materials are heat-treated to eliminate the binders and carbon. Then, the remaining constituents undergo burning at around 1600 °C, yielding an alloy containing CO, Ni, and other metals. Following that, the other metals are removed from the lithium carbonate.	Energetic emissions of dioxins, carbon dioxide, sulfides, and furans, loss of material	[64,65]
Hydrometallurgical	Rendering agents that precipitate, extract, or adsorb different metals like Co, Mn, and Ni are used to dissolve the crushed matter. In the solution left behind, lithium is still dissolved to create lithium carbonate by further filtration. Pretreatments along the hydrometallurgical route include discharging and dismantling. It uses less energy and produces less harmful gasses, allowing for higher purity than pyrometallurgical.	Strong acids, such as sulfuric acid, are used, which poses a problem with the waste generated because it requires downstream treatment	[14]
Bioleaching	Bacteria and fungi are used to produce organic acids that leach metals. Compared with the traditional hydrometallurgical process, acids are replaced with microorganisms, producing lower environmental impacts and material costs.	extended leaching cycle, slow kinetics, low bacterial activity, and challenging operating conditions	[66]
Ultrasonic treatment	Aluminum is subjected to agitation and ultrasonic washing to extract all electrode components. Ultrasonic waves could generate more pressure due to the cavitation effect, which would enable the dissolution and disintegration of substances that are insoluble in water.	The type of polymer binder used has a significant impact on the delamination process’ efficiency.	[67]
Eutectic Salt	Lithium iodide (LiI) and lithium hydroxide (LiOH) are mixed in a eutectic mixture for the recovery of spent materials. This combination melts at temperatures below 200 °C, turning it into a liquid at comparatively low temperatures while consuming less energy and resources than conventional methods.	Operational difficulties related to the non-uniformity of various batteries,	[68]

).

For example, conventional methods such as pyrometallurgical and hydrometallurgical methods, while having high material recovery rates, involve high costs, toxic and polluting chemical solutions, require high temperatures, and discharge hazardous waste, as well as need large amounts of energy. Recently, additional approaches have also been developed, such as bioleaching (which is part of biohydrometallurgy), ultrasonic treatments, and eutectic salt, which, however, still face many challenges, as shown in Table 5, and are not yet feasible on a commercial scale. Therefore, since there is currently no easy path for recycling lithium batteries, extending the service life of spent batteries may be possible to extract additional value. Remanufacturing, although all it does is postpone recycling, is therefore still the ideal option for spent batteries because it could maximize their value by minimizing emissions and energy consumption, as well as overuse of resources and critical raw materials, which could play a central role in avoiding a crisis in their supply.

4. Conclusions

Within this study, the potential environmental benefits of a second-life pathway through its reuse within a stationary power plant were verified through life cycle assessment. The results showed that a second life application could reduce GWP by −49.65 kg CO₂ eq/kWh, TEC by −3.70 kg 1.4 DCB eq/kWh, HNCT by −3.45 kg 1.4 DCB eq/kWh, −3.87 m²a crop eq/kWh and −10.98 kg oil eq/kWh compared to a first-life application. Notoriously, used LIBs are seen as a problem because, most of the time, they end up in landfills, although this practice is being discontinued following the new EU Regulation 2023/1542. In contrast, the results of this study show how, albeit theoretically, extending the life of batteries could mean reducing their environmental impacts and increasing the amount of renewable energy available on the grid. From an environmental point of view, second life is also potentially preferable to other forms of recycling, such as hydrometallurgical and pyrometallurgical recycling, as it shows lower environmental impacts in all impact categories considered, also considering the low maturity of the two recycling processes. However, the two processes are not alternatives but complementary, and it is still useful to show how a second-life process can be made with low environmental impact by extending its use. Thus, within a broad ecosystem of solutions for the energy transition, the results of this study highlight how storage facilities and second-life batteries could be tools that enable greater sustainability in the lifecycle perspective of electric vehicles. The demand for energy storage is certainly destined to grow significantly shortly due to the strong increase expected in the development of renewable energies, which, however, depend on exogenous factors (insolation and windiness) and therefore necessarily need storage systems, where the energy produced can be stored, both for its more adequate transfer to the grid and for its conservation at times when energy production is higher than demand (for wind, for example, the night phase). Therefore, the growing availability in the coming years of end-of-life batteries from electric vehicles seems to positively intersect with the also growing need for storage systems alongside renewable energy production. The second life of batteries, therefore, could be an opportunity, both as a potential to create new markets and new jobs and as an approach to the end-of-life of electric vehicle batteries that, in a circular economy perspective, would determine mitigation of the environmental impacts related to primary production. However, there remain some critical issues related to certain aspects. For example, it is important to point out that, for the system to work well, it is appropriate to use starting batteries that are as homogeneous as possible, in addition to the fact that even the same model of battery from two different vehicles may have had a completely different previous history, for example in the number of charge and discharge cycles, mechanical stresses, status of individual cells, and since it is not possible to determine these factors without disassembling the pack there is a risk of using batteries that may have a very different performance, risking compromising the efficiency of the overall system. Thus, such an approach presents the need to open the battery pack, disassemble the modules, and test their healthy state, with labor and costs that may make the second-life storage system uncompetitive. These aspects may therefore not make all batteries equally redirected to second life because, depending on how the pack is constructed, the processing time and cost may differ greatly from case to case. From this point of view, a possible opportunity could be more coordination by supply chain actors to make this possibility more efficient, encouraging a more assertive involvement of automakers and especially fostering standardization of battery pack construction methods so that disassembly and testing activities are less complex. For now, however, second life appears (at least) to be a sustainable solution.