Comparison of Lithium-Ion Recycling Processes for Electric Vehicle Batteries

Abstract

Over three hundred thousand battery electric vehicles (BEV) and plug-in hybrid electric vehicles (PHEV) are currently registered in the United States as of 2015, which is less than one percent of the total market share. A quickly growing market for electric vehicles (EV) will inevitably lead to a high number of EV batteries reaching the end-of-life (EOL). Manufacturers have to create processes to ensure a sustainable recycling management system, while still fulfilling government regulations. Recycling used EV batteries presents an economical and ecological challenge, considering the increased volume and diversity of car batteries, and the lack of a generalizable disposal process. Although the literature discusses the EOL issues with respect to Life Cycle Assessment (LCA), this paper presents a comprehensive literature review of recycling processes for lithium-ion batteries (LIB). This comparison explores the generalizability of the disposal processes for LIBs and quantifies the process value via Value Theory.

Full text

Proceedings of the 2016 Industrial and Systems Engineering Research Conference
H. Yang, Z. Kong, and MD Sarder, eds.
Comparison of Lithium-Ion Recycling Processes
for Electric Vehicle Batteries
Jan Engel and Gretchen A. Macht, Ph.D.
The University of Rhode Island
Kingston, RI
Abstract
Over three hundred thousand battery electric vehicles (BEV) and plug-in hybrid electric vehicles (PHEV) are
currently registered in the United States as of 2015, which is less than one percent of the total market share. A
quickly growing market for electric vehicles (EV) will inevitably lead to a high number of EV batteries reaching the
end-of-life (EOL). Manufacturers have to create processes to ensure a sustainable recycling management system,
while still fulfilling government regulations. Recycling used EV batteries presents an economical and ecological
challenge, considering the increased volume and diversity of car batteries, and the lack of a generalizable disposal
process. Although the literature discusses the EOL issues with respect to Life Cycle Assessment (LCA), this paper
presents a comprehensive literature review of recycling processes for lithium-ion batteries (LIB). This comparison
explores the generalizability of the disposal processes for LIBs and quantifies the process value via Value Theory.
Keywords
Electric Vehicles, Lithium-ion Batteries (LIBs), Recycling Processes
1. Introduction
Even though the target set by the U.S. government of having 1,000,000 electrically operating vehicles by 2015 has
not been achieved [1, 2], the number of registered electric vehicles will rise continuously and will inevitably lead to
an increased number of multiple types of EV batteries reaching the end-of-life (EOL) [2, 3]. Dismantling and
recycling vehicles needs to meet a minimum standard of 95% of the average vehicle weight in the EU currently, the
U.S. will follow in the nearby future (2000 EU ELV Directive) [4]. The battery weight (approximately 1200 lbs.) in
relation to the total car weight (approximately 4800 lbs.) of a TESLA Model S [5], for example, is approximately
25%, meaning the battery must definitely be a part of the recycling process. The development of a disassembly and
recycling networks is necessary to efficiently collect and recycle huge amounts of spent batteries [2, 6]. In the past,
for economic reasons, the recycling of cobalt, nickel, and copper was the main focus of LIB recycling processes.
However, a future shortage of lithium is predicted within the next 100 years, if recycling processes that can regain
90% of used lithium are not implemented [7, 8]. Research in this field of study is invaluable for the future and needs
to be intensified.
2. Electric Vehicle (EV) Lithium-ion Batteries (LIBs)
The most common battery technologies for EVs are lead-acid batteries, nickel-cadmium batteries, nickel-metal-
hybrid batteries, sodium-sulfur batteries, and LIBs [9]. LIBs are used extensively and exhibit superior cycle life
compared to similar technologies, but suffer from reduced power capabilities considering age and cycle [10]. LIBs
also show the highest specific energy density of up to 200 Wh/kg, a constant voltage discharging process, a low self-
discharging rate over time, and are simple to charge and maintain. The LIB type therefore fits the upcoming
requirements (charging infrastructure, charging time, driving range) regarding of electric vehicles the best [11]. LIB
cells are assembled in battery modules, which are subunits of the entire battery system. An extremely high number
of cells are packed together in a single plastic case, connected into modules with control circuitry attached. Lithium-
ion technology is based on a lithium-ion movement between the anode and cathode, forcing electrons to move
between them. Conventional batteries use a redox reaction to generate electricity instead [12]. The basic components
of a lithium-ion cell are cathode, anode, electrolyte and a separator [7, 10].

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Battery recyclers deal with difficult circumstances, such as diverse feedstock with numerous battery types, as well as
dealing with harmful and dangerous components. The disposal of EOL vehicle batteries is regulated by law (EU
Directive: by 2016 45% of used batteries must be collected and recycled each year [4]), which must be taken into
account by the producing manufacturers [6]. Manufacturers need to provide a sustainable, EV consumer free of
charge redemption solution for battery recycling. A generic recycling process for LIBs of EOL electric vehicles can
generally be structured as a sequence of collecting, sorting, handling, eliminating, and distributing, with the goal of
recovering useful battery materials [13]. A manufacturer can process the batteries themselves or be a part of a
cooperative recycling network. The basic principles of an industrialized recycling process for EV batteries are
illustrated in the Figure 1 below.
Figure 1: Industrialized Recycling Processes for EV LIBs
LIBs contain valuable components and materials that should be recovered by an efficient recycling process.
Currently, there are different methods to recycle LIBs, which combine various process operations. In those methods,
batteries are first mechanically processed, and then hydrometallurgically and pyrometallurgically processed [14, 15].
The deactivation step is used to minimize the risk of potential energized or chemical reactions of charged LIBs.
Deactivation covers thermal pretreatment to volatilize the electrolyte or decompose all organic compounds, or a
discharging step to reduce the hazard level, as well as freezing of the electrolyte to prevent further electrochemical
reactions. During the mechanical preparation process, LIB packs are disassembled into single components and often
manually dismantled or shredded [16, 17]. The mechanical treatment implies the crushing of batteries to open cells
and modules in order to sort and classify valuable materials, such as copper foil, aluminum foil, separator, and
coating materials. In pyrometallurgical processes, various components of battery cells are liquefied. These processes
enable the recovery of the transition metals nickel, cobalt, and copper, while lithium and aluminum remain in the
slag. To recover the lithium, further processing steps are necessary. Hydrometallurgical processes are used to
recover pure metals from coating materials, either from mechanical processes or from the resulting slag from the
pyrometallurgical processes. Hydrometallurgical processes, also include leaching of the educts, extraction,
crystallization, and precipitation [7, 18].
3. Recycling Process of LIBs
This paper presents a comprehensive literature review of recycling processes for LIBs [14, 15]. Several globally
operating industrialized recycling processes are able to disassemble and recycle LIBs were reviewed. Companies
and research institutes capable of recycling LIBs were discovered in Germany, Switzerland, and the United States.
An overview of current industrialized processes is depicted in the research papers of [19] and [20]. Different
combinations of unit operations (i.e. deactivation, mechanical treatment, hydrometallurgy, and pyrometallurgy)
result in different industrialized recycling processes for each company [21]. Comparisons of recycling methods can
provide further information about a possible generalizable process to dispose and recycle EV LIBs. All
industrialized recycling processes for EV LIBs differ in certain ways, that comprise a broad variety of methods, due
to the fact that the continuous development of battery systems in the area of design or materials has resulted in the

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lack of a standardized industrial recycling process. Only a handful of companies are making serious progress on the
recovery of lithium-ion in high purity [17].
The most promising and globally operating recycling companies with the potential to succeed in the area of EV LIB
recycling in the long run are reviewed in a more detailed way. Those companies are frequently mentioned in
literature, journals, reports, and in the media with a recognizable influence on the global market [9, 11, 14, 15, 20,
21]. Companies one, two, and three are using processes with the same basic unit operations: mechanical treatment
and hydrometallurgical processing. Company 5 insists on the recovery of lithium by pyrometallurgical process
operations only, whereas company 4 incorporates all four processes mentioned: deactivation, mechanical treatment,
and both hydro- and pyrometallurgical processing [11, 17]. To get a general overview of the comparability of the
different industrialized recycling processes, the following figure (Figure 2) shows a highly simplified visualization.
Figure 2: General Unit Operations of Industrialized Recycling Processes for EV LIBs
Comparing the different unit operations of the recycling companies, similarities become visible. Even though the
general treatments are mostly similar, the methods within these processes differ. The following figures illustrate the
similarities and differences within the mechanical treatment and hydrometallurgical process by analyzing the
recycling steps of companies 1, 2, and 3 (Figure 3). Additionally, some input and output material streams of the
specific processes are taken into account and visualized (Figure 3). The amount of data given strongly relies on the
available data output of made available by the analyzed recycling companies based on their websites or the reviewed
literature [9, 11, 14, 15, 20, 21].
Figure 3: Comparison Unit Operations/Material Flow: Company 1, Company 2, Company 3

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By contrast, the recycling company 4 relies on pyrometallurgical processes to recycle LIBs. Similarities are
noticeable in early process stages, in which the batteries undergo a similar pretreatment process. The following
figure illustrates the specific processes within the pyrometallurgical unit operation of company 4’s recycling process
in a simplified way. Additionally, all given data input and output material streams are visualized (Figure 4).
Figure 4: Unit Operations/Material Flow: Company 4
Company 5 demonstrates a recycling process for EV LIBs in which all operation units are used at least once during
the disposal and recycling process. Besides similar crossings in the pretreatment phase, the methods and material
streams differ within the unit operations. Figure 5 below illustrates the recycling process for EV LIBs of company 5,
besides showing the specific methods used within all treatment phases. All given data concerning material input and
output streams are visualized (Figure 5).
Figure 5: Unit Operations/Material Flow: Company 5
A general process of recycling LIBs should be a combination of different unit operations, in which lithium is
ultimately recovered. The different process paths are always a combination of deactivation, mechanical treatment,
hydrometallurgy, and/or pyrometallurgy [13]. All recycling processes for EV LIBs show comparable elements.
Analyzing the specific unit operations in a more detailed way, it is difficult to make a statement about the
comparability due to the company-based differences. The choice of process depends on the battery type, the battery
size, the construction, and the materials used [7]. Even though basic unit operations of industrialized EV LIB
recycling processes are identical, this does not indicate that the actual processes within these units are the same. An
in-depth analysis of the incoming and outgoing material streams mentioned is currently not possible using the
information provided by the companies. The amount of information is not enough to completely describe each
recycling step and material flow, making it challenging to compare these processes.
4. Value Theory of Recycling Processes of LIBs
Value Theory was applied to the industrialized recycling processes for EV LIBs found within the literature. The
purpose of establishing value for a particular process was to see if one process was either more powerful than
another or more generalizable. Since each recycling process occurs within industry, there is little to no uncertainty in
the recycling process and it is not a prediction of future use, capacity, or yield.

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To quantify the process value of recycling EV LIBs via Value Theory (Figure 6), three different criteria have been
established. Each criterion was valued with a specific weight, depending on the importance of the processes, and
treated in an additive model, as they are mutually and preferentially independent. The criteria evaluated are the
recycling efficiency, the CO2 recycling saving potential, and the recycling capacity. The criteria weights were scale-
based, depending on the reviewed literature and authors’ assessment. A scale from 1 to 9 (i.e., scale = {1, 3, 5, 7, 9})
was set up to rate the previously established criteria for the different recycling processes of each company. Within a
specific interval, the criteria were graded according to the scale demonstrated in Figure 6. In the end, the goal was to
get a process rating value and quantify the different industrialized processes.
Figure 6: Value Theory – Companies Recycling Processes (RP) for EV LIBs
Data found in research literature, articles, news reports, and information on company websites were implemented
into Figure 6 [9, 11, 14, 15, 20, 21]. Even though all reviewed recycling processes run on an industrialized basis,
there are limited data available. Regarding the recycling efficiency, the targets set by the companies are in
accordance with the 2000 EU ELV Directive to recycle 95% of the vehicle’s weight [4]. Detailed information about
the current recycling efficiency of the companies is not stated by the firms. Yet, even the companies who have
reported on efficiency are currently performing well under those standards. Additionally, the values illustrating the
CO2 recycling saving potential are not specifically mentioned anywhere, yet are simply advertised as “efficient
processes.” Comparable values were given regarding the recycling capacity for LIBs, leading to a somewhat
comprehensive rating. Unfortunately due to the lack of currently published information, the value theory evaluation
(and thus a best process or even generalizable model) could not be obtained. The companies are currently facing
constant competition in order to maintain a leading role in the global competitive market for recycling EV LIBs;
therefore the firms share limited information.
5. Conclusion
A growing market for electric vehicles will inevitably lead to a high number of EV batteries reaching the EOL.
Manufacturers have to consider creating disassembly plans and processes to ensure a sustainable recycling
management system, while still fulfilling government regulations [11]. In the past, for economic reasons, the
recycling of cobalt, nickel, and copper was the main focus of LIB recycling processes. However, a future shortage of
lithium is predicted within the next 100 years, if recycling processes that can regain 90% of used lithium are not
implemented [7, 8]. Research in this field of study is invaluable and needs to be intensified. Lithium-ion batteries are
highly standardized with regard to dimensions and performance classes, which provides a high planning reliability.
Due to a continuous development of battery systems in the area of design or materials, however, no standardized

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industrial recycling process for EV LIBs currently exists [7, 16]. Uncertainty factors in the areas of metal prices,
recycling processes, battery lifespan, and prevalent LIB technology will influence the future recycling development
process. A company-wide automation of disassembly sequences of battery systems is difficult to achieve due to the
large variety of battery systems.
Overall, the purpose of this work was to compare and contrast various methods of recycling EV LIBs via Value
Theory. The companies are currently facing constant competition in order to maintain a leading role in the global
competitive market for recycling EV LIBs; therefore, the firms share limited information. This effort could currently
not be completed; future work will attempt to pursue a completed Value Theory analysis through interviews with
these companies. Additionally, there is potential for more attributes of comparison to arise, which might change the
output and the type of model used (i.e., additive or multiplicative).
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