Chemosphere 77 (2009) 1132–1136

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Chemosphere
journal homepage: www.elsevier.com/locate/chemosphere

Technical Note

A combined recovery process of metals in spent lithium-ion batteries

Jinhui Li a,*, Pixing Shi a, Zefeng Wang a, Yao Chen a, Chein-Chi Chang b
a
Department of Environmental Science and Engineering, Tsinghua University, China
b
Department of Civil and Environmental Engineering, University of Maryland, Baltimore County, USA

a r t i c l e i n f o a b s t r a c t

Article history: This work proposes a new process of recovering Co from spent Li-ion batteries (LIBs) by a combination of
Received 13 February 2009 crushing, ultrasonic washing, acid leaching and precipitation, in which ultrasonic washing was used for
Received in revised form 24 August 2009 the first time as an alternative process to improve the recovery efficiency of Co and reduce energy con-
Accepted 24 August 2009
sumption and pollution. Spent LIBs were crushed with a 12 mm aperture screen, and the undersize prod-
Available online 22 September 2009
ucts were put into an ultrasonic washing container to separate electrode materials from their support
substrate. The washed materials were filtered through a 2 mm aperture screen to get underflow products,
Keywords:
namely recovered electrodes. Ninety two percent of the Co was transferred to the recovered electrodes
Recycling
Crushing
where Co accounted for 28% of the mass and impurities, including Al, Fe, and Cu, accounted for 2%.
Ultrasonic washing The valuable materials left in 2–12 mm products, including Cu, Al, and Fe, were presented as thin sheets,
Acid leaching and could be easily separated. The recovered electrodes were leached with 4.0 M HCl for 2.0 h, at 80 °C,
Chemical precipitation along with concurrent agitation. Ninety seven percent of the Li and 99% of the Co in recovered electrodes
could be dissolved. The impurities could be removed at pH 4.5–6.0 with little loss of Co by chemical pre-
cipitation. This process is feasible for recycling spent LIBs in scale-up.
Ó 2009 Elsevier Ltd. All rights reserved.

1. Introduction active material. Castillo et al. (2002) reported a recycling process

containing thermal treatment, which aimed at eliminating the car-
Lithium-ion batteries (LIBs) are widely used in laptops, mobile bon and organic compounds in solid residues obtained from an
phones, video-cameras and other portable electronics. The use of acid-leaching process. Saeki et al. (2004) developed a process of
LIBs, which consist of crust, electrodes (usually copper foil for neg- co-grinding LiCoO2 with polyvinyl chloride, to form Li and Co-chlo-
ative electrodes and aluminum foil for positive electrodes), electro- rides. Contestabile et al. (2001) presented a dissolution process, in
lyte, and polymer (Contestabile et al., 2001; Lee and Rhee, 2003), which the battery rolls were treated with N-methylpyrrolidone to
has increased sharply in recent years because of their function up- separate LiCoO2 from their support substrate. Acid leaching is an
date and cost decrease. It is necessary to recycle lithium cobalt effective method to separate LiCoO2 from graphite and other mate-
oxide (LiCoO2), which is adopted as cathode active material, be- rials. Several different acidic media have been tested to dissolve Li
cause Li and Co are not only rare metals, but also hazardous to and Co in electrode materials (Zhang et al., 1998; Lee and Rhee,
the environment. Some processes to reclaim Co, Li, Cu, and Al from 2002; Nan et al., 2005; Xu et al., 2008). Alternatively, bio-leaching
spent LIBs have been reported, but so far, only a few of them have processes have also been tried (Mishra et al., 2008). Chemical treat-
been applied in industrial practice (Bernardes et al., 2004; Espinosa ment was usually used as a final step in these processes to recover
et al., 2004; Xu et al., 2008). metals in spent LIBs. Nan et al. (2006) and Mantuano et al. (2006)
Pretreatment is necessary in order to recycle metals in spent both presented a solvent extraction method to recover copper and
LIBs. Shin et al. (2005) presented a mechanical separation process cobalt, respectively. Chemical precipitation was used by Contesta-
consisting of a two-step crushing, primary crushing with a sieve of bile et al. (2001) and Castillo et al. (2002) to extract precious met-
20 mm size and fine crushing with a sieve of 10 mm size, followed als from the acid-leaching solution. Lupi et al. (2005), Freitas and
by a hydrometallurgical procedure for lithium and cobalt recovery. Garcia (2007) both conducted electrochemical processes to recover
Lee and Rhee (2002) treated the LIBs in a muffle furnace, obtaining cobalt from spent LIBs. In addition, Paulino et al. (2008) compared
LiCoO2 by burning off the carbon, which was adopted as negative chemical precipitation and solvent extraction processes for the
recycling of spent LIBs.
This work presented here aimed at testing a new combined pro-
* Corresponding author. Address: Department of Environmental Science and cess to recycle precious metals, especially Co. This process can be
Engineering, Tsinghua University, Sino-Italia Environmental Energy Building, Room
804, Haidian District, Beijing 100084, China. Tel.: +86 10 6279 4143; fax: +86 10
described as follows: (1) exploring new physical pretreatment
6277 2048. methods to decrease both costs and pollution, (2) optimizing the
E-mail address: jinhui@tsinghua.edu.cn (J. Li). condition of acid-leaching process to increase the leaching

0045-6535/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.chemosphere.2009.08.040
 J. Li et al. / Chemosphere 77 (2009) 1132–1136 1133

efficiency of Co, and (3) selecting appropriate precipitators and concentration on leaching efficiency were studied. Finally, a
conditions to maximize the recovery efficiency and the purity of chemical precipitation method was used to remove the impurities
Co. By using a combination of ultrasonic washing, the investigation in the solution and to recover Co and Li, in which the influence of
of acid leaching and chemical precipitation, a recycling process for pH was tested.
spent LIBs has been developed, in which ultrasonic washing was
used for the first time as an alternative process to improve the
recovery efficiency of Co, and to reduce energy consumption and
pollution.
a
2. Materials and methodology

2.1. Materials

The spent LIBs used in this study were provided by TES-AMM

Co. Ltd. LiCoO2 and carbon powders were fixed on Al and Cu foils 29
as positive and negative electrodes, respectively. The components
b
of LIBs were separated and measured in the laboratory as follows.

Content of Co (%)
First, the crust was removed with pincers and saws. Then, all of the
28
parts were put into hydrochloric acid, heated and agitated at 90 °C
for 4 h, dissolving all of the metals. The concentrations of different 27
metals were measured with an inductive coupled plasma atomic
emission spectrometer (ICP-AES). Finally, the content of each metal
26
in the battery was calculated. The results indicated that Co ac-
counted for 16% and Li, Cu, Al, Fe accounted for 2%, 10%, 3%, and
19% of the mass, respectively. 25

2.2. Spent LIBs recycling process

8 c
7 Cu Al Fe All impurities
Content of impurities (%)

The process for separating the materials in LIBs such as poly-

mer, electrodes, crust materials, and electrodes is shown in 6
Fig. 1. Spent LIBs were put into the crusher and the screen under- 5
flow materials were treated in an ultrasonic washing container
with agitation, with an ultrasonic frequency and electric power 4
of 40 Hz and 100 W, respectively. This process was aimed at sep- 3
arating LiCoO2 from the Al foils, and separating carbon power
from the Cu foils. In this step, the influences of the size of the 2
aperture, as well as of the temperature and duration of ultrasonic
1
washing were explored. Then a 2 mm aperture screen was used
to select the screen underflow materials called recovered elec- 0
trodes from the washed materials mentioned above. Following 2 4 8 12
this sifting, hydrochloric acid was used to dissolve the recovered Crusher screen size (mm)
electrodes, and the influences of duration, temperature, and H+
Fig. 2. Effect of the size of crusher screen on: (a) upflow products; (b) content of Co
in underflow products; and (c) content of impurities in underflow products.

Spent LIBs

upflow
Crushing+Screening Organic membrane

upflow
Ultrasonic washing+Screening Al, Cu, Fe mixture

underflow
Recovered Electrodes

upflow
Acid leaching+Filtering Carbon powder

upflow
Precipitation+Filtering Co compounds

Solution to be treated Fig. 3. LiCoO2 separation efficiency from Al foils under condition of: (a1) using
agitation alone; (a2) using ultrasonic washing alone; and (a3) using agitation and
Fig. 1. Flowchart of spent LIBs recycling process. ultrasonic washing simultaneously.
1134 J. Li et al. / Chemosphere 77 (2009) 1132–1136

100 amounts. Using a crusher with a 2 mm aperture screen, however,

a left some Al, Cu and electrodes among the larger products. The re-
sult was the same when using a 4 mm aperture screen, and even
Removal efficiency (%)

90 when the 8 mm aperture screen was used, small amounts of elec-

trode materials, such as Al and Cu still remained among the larger
80 components. When using the 12 mm aperture screen, however, no
electrode materials were found in the larger products (Fig. 2a). ICP-
AES analysis results from the 12 mm aperture (Fig. 2b) indicated
70 that Co accounted for a larger percentage of the underflow, while
the impurities, such as Cu, Al, Fe, and etc., were present in a lower
60 concentrations (Fig. 2c). As Co was combined into LiCoO2, the con-
tent of Li changed along with Co. With smaller screen apertures,
the amount of impurities entered into the undersize products of
50 the crusher increased. A crushing process using a 12 mm aperture
25 40 55 70 85 screen resulted in 28% Co and 2% impurities in the recovered elec-
Temperature ( oC) trodes, which represented the best results in our experiment.
100 In order to determine whether ultrasonic washing and agitation
b are necessary for electrodes separation, experiments were con-
Removal efficiency (%)

90 ducted using each process separately, immersing the LIBs in a

55 °C water bath for 10 min. During the manufacturing process, or-
80 ganic binder was used to paste LiCoO2 onto Al foils. After a long-
70 term use, part of the organic binder had probably volatilized, and
Removal efficiency at the residual part would not be as steady as before. Therefore, Li-
60 55°C with a 10 min CoO2 would not cling firmly to the Al foils (Fig. 3a), and it is easy
agitation to be separated by a physical process. When using agitation alone,
50 most of the electrode materials still stuck to the foils (Fig. 3a1);
when using ultrasonic washing alone, only part of the electrode
40
5 10 15 20 materials could be removed (Fig. 3a2). But when the agitation
Time (min) and the ultrasonic washing were employed simultaneously, almost
all electrode materials could be separated from Al foils (Fig. 3a3). It
Fig. 4. Effect of temperature (a) and duration time (b) on removal efficiency of
may be that the cavitation effect of the ultrasonic wave can gener-
electrodes from Al and Cu foils when using ultrasonic washing and agitation.
ate greater pressure to destroy insoluble substances and scatter
them in the water. The rinse effect of agitation then facilitates
3. Results and discussion the process of separating electrode materials from Al foils.
Temperature also affected the processing efficiency. Using
3.1. Crushing and ultrasonic washing ultrasonic washing and agitation, 92% of the electrodes was re-
moved at 55 °C, but the removal ratio decreased to 76% at 85 °C,
In order to ensure the efficiency of recovery, it is preferred that and the electrodes could not be completely separated from the Al
LiCoO2 should only be present in the larger products in minimal foils (Fig. 4a). This is mainly because at higher temperatures the

Fig. 5. Products obtained after crushing and ultrasonic agitation washing process: (b1) oversize products of 12 mm aperture screen, mainly containing organic membrane;
(b2) products between 2 mm and 12 mm aperture screen, mainly containing Cu foil, Al foil and Fe crust; and (b3) electrodes with few impurities.
 J. Li et al. / Chemosphere 77 (2009) 1132–1136 1135

force caused by the collapse of the ultrasonic cavitation bubble is

100 a
Leaching efficiency (%)

relatively small, and it cannot completely destroy the binding

90 agent between electrode materials and Al foils. Ultrasonic washing
80 separation at a temperature below 55 °C was proposed, both to
Co
70 conserve energy and to produce better results. In order to explore
the relationship between removal efficiency and duration in ultra-
60 Li
sonic washing, the electrode removal efficiency under room tem-
50 perature was studied. Under room temperature, with 15 min of
40 agitation, the same removal ratio as at 55 °C with a 10 min agita-
30 tion could be achieved (Fig. 4b). Thus, it is recommended that
40 50 60 70 80 90 100 the duration be prolonged in order to reduce the temperature to
Temperature ( ) room temperature.
A process of material separation was proposed based on the re-
100 sults of the above experiment. This process consisted of three
b
Leaching efficiency (%)

steps: (1) spent LIBs were crushed with a 12 mm aperture screen;

90 (2) the smaller materials from the 12 mm aperture were put into
Co an ultrasonic washing machine with agitation equipment for
80 15 min; and (3) the washed materials were put into a container
with a 2 mm aperture screen, which was determined by the equip-
70 Li ment applied in this study and could be optimized in further re-
search. Subsequently, the underflows, namely recovered
60 electrodes, would be treated by an acid-leaching process in the
next step. Through this process, three types of products could be
50 obtained, as shown in Fig. 5. During the pretreatment process, only
1.0 2.0 3.0 4.0 5.0
one step of crushing was applied and only water was used to wash
H+ concentration (M)
the recovered electrodes. Compared with the two-step crushing
(Shin et al., 2005) and with treating the LIBs in a muffle furnace
100
c (Lee and Rhee, 2002), this process is energy-saving because the en-
Leaching efficiency (%)

90 ergy used in ultrasonic washing machine is much lower than that

used in crushing machine; compared with thermal treatment (Cas-
80 tillo et al., 2002) and treatment with organic solvent (Contestabile
Co et al., 2001), it is more environmentally sound because little organ-
70 ic wastewater and toxic gas were generated.
Li
60
3.2. Acid-leaching process
50
The efficiency of the acid-leaching process could be influenced
40 by H+ concentration, temperature, reaction time and solid-to-li-
30 60 90 120 150 180 quid ratio (S/L). According to Zhang et al. (1998), the influence of
Reaction time (min) S/L on leaching is not obvious. In order to optimize the operational
Fig. 6. Effect of: (a) temperature (C Hþ ¼ 4 M, t = 2.5 h); (b) H+ concentration
conditions for the acid-leaching process, experiments were de-
(T = 80 °C, t = 2.5 h); and (c) reaction time (C Hþ ¼ 4 M, T = 80 °C) on the acid signed to explore the influences of reaction time, H+ concentration
leaching efficiency of cobalt and lithium from recovered electrodes. and temperature. When the temperature was 80 °C (Fig. 6a), H+

60 100
Removal efficiency of impurities (%)

50
80

40
Loss of Co (%)

60

30

40
20
Co
All impurities
Al 20
10
Cu
Fe

0 0
4.0 4.5 5.0 5.5 6.0 6.5 7.0
pH

Fig. 7. Effect of pH on the removal efficiency of impurities from acid-leaching solution and loss of cobalt during this process.
1136 J. Li et al. / Chemosphere 77 (2009) 1132–1136

concentration was 4 M (Fig. 6b) and reaction time was 2 h (Fig. 6c), one represented in this paper are more effective in processing
a high leaching efficiency was achieved; 97% of the Li and 99% of spent LIBs than in processing lithium polymer ion secondary bat-
the Co were dissolved. teries. However, recycling technologies for lithium polymer ion
secondary batteries also need to be explored in time.
3.3. Chemical precipitation

After the recovered electrodes were dissolved by hydrochloric Acknowledgements

acid under the conditions of 4.0 M H+, 80 °C, 2.0 h, and agitation,
the insoluble substances could be removed by a filter. The concen- This work was financially supported by the National Key Tech-
tration of the main elements including Co, Li, Cu, Al and Fe in the nology R&D Program under Grant number 2006BAC02A18, and the
acid leachate of recovered electrodes was 4.42, 0.76, 0.09, 0.19, Science and Technology Programs of Jiangsu Province.
and 0.38 g L1, respectively. According to the differences of the sol-
ubility product constant between different Mn+(OH)n, these metals
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