CHEM 280 Alabama Mechanism of the Recharge Ability of Lithium Ion Batteries Questions

The provided reading materials consist of two review articles and one research article on lithium- ion batteries. These articles describe a wide-range aspect of lithium-ion batteries including the basic functions, mechanism, degradation as well as a potential recycling approach of lithium-ion batteries.11 questions plus short summary (<10 lines).

CHEM 280 Spring 2021
Reading Assignment 2
Assigned 04/05/2021, due 04/19/2021
Introduction:
The provided reading materials consist of two review articles and one research article on lithiumion batteries. These articles describe a wide-range aspect of lithium-ion batteries including the
basic functions, mechanism, degradation as well as a potential recycling approach of lithium-ion
batteries.
Instructions:
–
Answers must be written in an organized, concise, and legible manner or your assignment
will be returned without being graded.
Your complete assignment must be stapled. 4 points penalty will be imposed for an
unstapled assignment.
This assignment is worth 40 points.
Please read the review article entitled “Recent advances in rechargeable battery materials: a chemist’s
perspective” and answer the following questions in your own words:
1) The three main components of lithium-ion batteries are i) cathode electrode, ii) anode
electrode, and iii) electrolyte. Provide one example of materials for each component.
What is a characteristic of the chosen materials that makes them suitable as anode,
cathode, and electrolyte?
2) Lithium-ion batteries are rechargeable, and therefore, they are classified as secondary
batteries. Explain the mechanism of the recharge ability of these batteries.
3) The uses of lithium-ion batteries are wide-spread despite of Li being a rare metal among
the alkaline metals such as Na. Please use the concept of cell potentials (or reaction
potentials) to explain the advantage of Li-ion batteries over Na-ion batteries.
4) Recent advancements of lithium-ion batteries have been made by employing solid
polymer electrolytes. What are the advantages and disadvantages of these type of
electrolytes?
Please read the research article entitled “Sustainable recovery of cathode materials from spent lithium-ion
batteries using lactic acid leaching system” and answer the following questions in your own words:
5) What is the purpose of an acid-leaching process?
6) The article describes that the main drawback of using inorganic acids such as HCl,
HNO3, and H2SO4 for a leaching process in a presence of strong oxidizing agent such as
H2O2 is the generation of toxic gases. What is the toxic gas produced from the reaction
between HCl (aq) and H2O2 (aq)? Support your answer with a balanced chemical
equation.
7) What are the metal ions being recycled? What are the form of impurities of these ions
that were identify after the heat treatment of the spent lithium-ion battery samples?
8) The article also describes the optimization of the leaching process by varying reaction
parameters such as concentration of lactic acid, S/L ratio, temperature, amount of H2O2,
and time. Please provide the optimized conditions of this leaching process.
9) What is the role of H2O2 and lactic acid in the leaching process.
Please read the research article entitled “Aging mechanisms of electrode materials in lithium-ion batteries for
electric vehicles” and answer the following questions in your own words:
10) The recharge ability of lithium-ion batteries relies on the reversible insertion and
extraction of Li ions between the two electrodes. One of the aging mechanisms of these
batteries involves depletions of Li ions. Provide two causes for the loss of lithium ions.
Briefly explain.
11) Recommended operating temperatures of lithium-ion batteries are between –20 °C and
60 °C. The use of these batteries at elevated temperature or in direct sunlight may lead
to the generation of excessive heat, ignition, and lose of efficiency. Briefly explain the
effect of heat on the efficiency of lithium-ion batteries.
Lastly, in your own word, write a short summary ( solid/liquid ratio
amount of H2O2 > time
73.007
66.268
42.992
69.705
55.500
65.892
65.638
62.080
63.290
64.838
73.748
64.955
69.795
64.595
79.215
64.852
effect factor
Li
Ni
K1
K2
K3
K4
extreme
deviation
priority order
17.507
1.673
36.223
7.625
effect factor
Co
K1
K2
K3
K4
extreme
deviation
> temperature > priority order
81.040
67.425
61.015
52.112
Mn
28.928
K1
K2
K3
K4
extreme
deviation
lactic acid concentration > solid/liquid ratio > temperature > priority order
amount of H2O2 > time
temperature
time
acid
H2O2
S/L
ratio
72.477
55.795
63.260
70.055
66.070
66.040
64.712
64.765
42.670
65.715
73.852
79.350
69.360
62.045
65.108
65.075
81.200
66.080
61.498
52.810
16.682
1.358
36.680
7.315
28.390
lactic acid concentration > solid/liquid ratio
temperature > amount of H2O2 > time
76.410
68.448
43.617
72.333
56.983
69.140
67.657
65.067
65.550
66.162
76.697
66.850
71.428
66.620
82.398
66.120
19.427
2.978
38.781
7.266
>
80.813
70.735
64.460
54.363
26.450
lactic acid concentration > solid/liquid ratio >
temperature > amount of H2O2 > time
36.51, and 37.16%, respectively, at a low lactic acid
concentration, i.e., 0.25 mol L−1. The leaching efficiencies of
the four metals increase rapidly with increasing lactic acid
concentration from 0.25 to 1.0 mol L−1. Almost 98% of Ni, Co,
and Mn and 93% of Li are leached at a lactic acid concentration
of 1.0 mol L−1. As the concentration increases from 1.0 to 1.5
mol L−1, the Li-leaching efficiency increases to 96.73%, but
those of the other metals change little. When the concentration
is greater than 1.5 mol L−1, there is a small improvement in the
efficiency. The optimum initial lactic acid concentration is
therefore 1.5 mol L−1.
Effect of S/L Ratio on Acid Leaching. Figure 4b shows the
effect of the S/L ratio on the leaching efficiency under the
conditions lactic acid concentration of 1.5 mol L−1, 0.5 vol %
H2O2, temperature 60 °C, and leaching time 30 min. The
leaching efficiencies of the four metals decrease slightly as S/L
increases from 10 to 20 g L−1. However, the leaching
efficiencies of Ni, Co, Mn, and Li decrease to 88.52, 88.4,
88.69, and 91.81%, respectively, at an S/L ratio of 40 g L−1. In
terms of a high leaching efficiency, the best S/L ratios is 20 g
L−1. Meanwhile, when the S/L ratio increases to 40 g L−1, the
leaching efficiencies of metals are still higher than 80%, which is
acceptable in the scale-up industry applications.
this shows that most of the PVdF and acetylene black was
burned off during calcination.
Acid Leaching. Order of Parameter Effects on Leaching
Process. Orthogonal experiments were performed to determine
the order of parameter effects on the leaching process. The
results and analysis are shown in Tables 2 and 3. The presence
of Ni, Co, Mn, and Li in the solution indicates that
LiNi1/3Co1/3Mn1/3O2 reacts with lactic acid (Table 2). The
concentrations of these metals in solution frequently change
depending on the conditions; this indicates that the five
conditions jointly influence the leaching efficiency. The
obtained results (Table 3) show that the conditions affect the
leaching process in the order lactic acid concentration, S/L
ratio, temperature, amount of H2O2, and leaching time.
Use of Single Variable to Explore Optimum Conditions for Leaching Process. Effect of Lactic Acid
Concentration on Acid Leaching. The orthogonal experimental results show that the concentration of lactic acid
significantly affects the leaching process. The concentration of
lactic acid was varied from 0.25 to 2.0 mol L−1 at 60 °C, with an
S/L ratio of 15 g L−1, a reductant concentration of 0.5 vol %
H2O2, and a leaching time of 30 min. Figure 4a shows that the
leaching efficiencies of Ni, Co, Mn, and Li are 38.81, 39.13,
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Figure 4. Effect on leaching efficiency of (a) initial acid concentration, (b) solid/liquid ratio, (c) temperature, (d) amount of H2O2, (e) reaction
time, and (f) metal leaching efficiencies under optimized conditions.
Effect of Temperature on Acid Leaching. We also
investigated the effect of temperature on the efficiency of
waste LiNi1/3Co1/3Mn1/3O2 leaching. The temperature varied
from 40 to 90 °C; the other conditions were lactic acid
concentration of 1.5 mol L−1, 0.5 vol % H2O2, S/L ratio of 20 g
L−1, and leaching time of 30 min. Figure 4c shows that almost
67% of Ni, Co, and Mn and 69.6% of Li can be leached at 40
°C. The leaching efficiencies increase rapidly to 90% at 50 °C.
More than 96.7% of Li, Ni, Co, and Mn is leached at 70 °C. A
plateau is observed above 70 °C. A temperature of 70 °C is
therefore suitable for the leaching process.
Effect of Amount of H2O2 on Acid Leaching. Figure 4d
shows the effect of the volume concentration of H2O2 (vol %)
on leaching for a leaching time of 30 min at 70 °C. Only about
33.22% of Ni, 33.63% of Co, 30.72% of Mn, and 59.34% of Li
are leached without the addition of H2O2. The leaching
efficiencies of Ni, Co, Mn, and Li increase to 96.27, 96.73,
96.32, and 96.84%, respectively, with increasing H 2 O 2
concentration from 0 to 0.5 vol %. However, the leaching
efficiencies of the metals are almost constant at H 2 O2
concentrations from 0.5 to 3 vol %. This confirms that a low
volume concentration of H2O2 (0.5 vol %) is sufficient for the
leaching process.
Effect of Leaching Time on Acid Leaching. The effect of
the reaction time on the leaching efficiency was investigated
from 10 to 60 min under the following conditions: lactic acid
concentration of 1.5 mol L−1, S/L ratio of 20 g L−1, 0.5 vol %
H2O2, and temperature 70 °C. The leaching efficiencies of the
different metals rapidly reach more than 95% at 10 min (Figure
4e). At 20 min, the total efficiencies are about 98%. Extending
the time from 20 to 60 min does not improve the efficiencies,
which indicates that acid leaching reaches its reaction
equilibrium within 20 min.
Kinetic Analysis of LiNi1/3Co1/3Mn1/3O2 Leaching with
Lactic Acid. Multimetal leaching in acid solution was
investigated by performing kinetic studies for different leaching
times (0−30 min) and temperatures (40−80 °C) under the
following conditions: lactic acid concentration of 1.5 mol L−1,
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Figure 5. Effects of reaction temperature and time on the leaching rates of Li (a), Ni (b), Co (c), and Mn (d) (1.5 mol L−1, 0.5 vol % H2O2, S/L
ratio of 20 g L−1).
Figure 6. Plots of ln(−ln(1 − x)) vs ln t at different reaction temperatures: Li (a), Ni (b), Co (c), and Mn (d).
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Table 4. Parameters of the Kinetics Model for Li, Ni, Co, and Mn at Different Leaching Temperatures
Li
Ni
Co
Mn
T (°C)
n
ln k
R2
n
ln k
R2
n
ln k
R2
n
ln k
R2
40
50
60
70
80
0.8094
0.8486
0.6319
0.6251
0.7740
−2.6843
−2.1250
−0.8647
−0.4704
−0.1087
0.9746
0.9918
0.9876
0.9671
0.9606
0.8710
0.8785
0.6307
0.6683
0.7648
−2.9053
−2.2392
−0.9188
−0.5934
−0.2698
0.9903
0.9872
0.9649
0.9687
0.9893
0.8559
0.8742
0.6356
0.6362
0.7593
−2.8480
−2.2178
−0.9254
−0.5452
−0.2873
0.9887
0.9881
0.9701
0.9761
0.9702
0.9464
0.9138
0.6136
0.6666
0.7145
−3.1152
−2.3130
−0.8226
−0.5419
−0.1857
0.9955
0.9920
0.9873
0.9693
0.9609
Figure 9. XRD and SEM patterns of R-NCM (a) and F-NCM (b)
samples.
core models. The Avrami equation is therefore used to explain
the leaching kinetics:
Figure 7. Arrhenius plots for the leaching of Li, Ni, Co, and Mn in the
temperature range 313.15−353.15K.
ln[− ln(1 − x)] = ln k + n ln t
−1
S/L ratio of 20 g L , and 0.5 vol % H2O2. The results are
shown in Figure 5. The optimum leaching conditions identified
in the kinetic studies are in agreement with those already
obtained (Figure 4).
Metal leaching from the cathode materials is a solid−liquid
heterogeneous reaction and is considered to occur on the outer
surfaces of unreacted particles. Multimetal leaching kinetics has
been successfully interpreted on the basis of shrinking-core
models and the Avrami equation.41−43 However, the metal
extraction data shown in Figure 5 do not fit various shrinking-
(2)
where x is the fraction reacted (i.e., leaching rate), k is the
reaction rate constant (min−1), n is a suitable parameter, and t
is the reaction time (min). Fitting plots of ln[−ln(1 − x)]
versus ln t at different temperatures for different metals, based
on the data in Figure 5, are shown in Figure 6. The plots show
good linear relationships for Li, Ni, Co, and Mn with R2 values
all greater than 0.96 (Table 4). This shows that the Avrami
equation describes well the leaching process under the given
leaching conditions. The values of n are calculated to be 0.5−1.
This indicates that the initial reaction rate is high and
Figure 8. Possible products and mechanism in the lactic acid leaching process.
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Figure 10. Electrochemical performances of R-NCM and F-NCM samples: (a−c) cycling performances at 0.2 C, 0.5 C, and 1 C, (d) rate
performances at different currents, (e) charge/discharge profiles at 0.2 C, and (f) Nyquist plots in the frequency range of 100 kHz to 0.01 Hz.
Mechanism of Acid Leaching. Lactic acid (C3H6O3) is an αhydroxy acid and contains a carboxyl group adjacent to a
hydroxyl group. The presence of an α-hydroxyl group increases
the acidity compared with that of an average monobasic acid.
The pKa of lactic acid is 3.86. The possible products and
mechanism of the reaction of LiNi1/3Co1/3Mn1/3O2 with lactic
acid are shown in Figure 8. This reaction occurs at the liquid−
solid interfaces, and the reaction rate is influenced by the acid
concentration, S/L ratio, amount of reductant, reaction
temperature, and reaction time. This leaching reaction is
mainly controlled by the chemical reaction, and the leaching
reaction between LiNi1/3Co1/3Mn1/3O2 and lactic acid is a
multiphase reaction, which can be explained in two steps: (1)
conversion of high valence Ni, Co, and Mn to Ni2+, Co2+, and
Mn2+ in the presence of H2O2 and subsequent dissolution of
spent LiNi1/3Co1/3Mn1/3O2 in the acid solution and (2) the
chelation of Ni2+, Co2+, Mn2+, and Li+ with lactate. The
leaching reaction can be represented as
continually decreases with time until the reaction reaches
equilibrium.42
The Arrhenius equation is used to describe the relationship
between reaction rate constant and the reaction temperature:
k = A e−Ea / RT
(3)
where k is the reaction rate constant (min−1), A is the preexponential factor, Ea is the apparent activation energy (kJ/
mol), R is the universal gas constant (8.314 J/K/mol), and T is
the absolute temperature (K). The activation energies of the
leaching reactions are usually calculated by the linear form of
the Arrhenius equation.
ln k = ln A −
Ea
RT
(4)
Plots of ln k (see in Table 4) versus 1/T are shown in Figure
7, and the activation energies for the leaching of Li, Ni, Co, and
Mn are 62.81, 63.96, 62.83, and 70.62 kJ/mol, respectively,
indicating that the rate-controlling step of this leaching process
is the surface chemical reactions.
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important effects on the leaching efficiencies of the four metals.
More than 98% of Ni, Co, Mn, and Li can be leached from
spent LiNi1/3Co1/3Mn1/3O2 under the optimum leaching
conditions: 1.5 mol L−1 lactic acid, 0.5 vol % H2O2, a relatively
low temperature of 70 °C, an S/L ratio of 20 g L−1, and a short
time of 20 min. The leaching kinetics of Li, Ni, Co, and Mn can
be explained by the Avrami equation. The leaching mechanism
was investigated in terms of the material structure.
The regenerated cathode material has a high specific capacity,
good rate capability, and excellent cycling performance
compared with those of freshly synthesized LiNi1/3Co1/3Mn1/3O2. More importantly, lactic acid has proved
an effective chelating agent for the sol−gel method. This
closed-loop recycling process for regenerating spent LIB
cathode material for LIBs will enable conservation and
recycling of resources.
3LiNi1/3Co1/3Mn1/3O2 (s) + 9C3H6O3(aq) + 1/2H 2O2
→ 3C3H5O3Li(aq) + (C3H5O3)2 Ni(aq)
+ (C3H5O3)2 Co(aq) + (C3H5O3)2 Mn(aq)
+ 5H 2O(l) + O2 (g)
(5)
Characterization and Electrochemical Performance of
Regenerated LiNi1/3Mn1/3Co1/3O2. Figure 9 shows XRD
patterns and SEM images of the regenerated LiNi1/3Co1/3Mn1/3O2 (R-NCM) and freshly synthesized LiNi1/3Co1/3Mn1/3O2 (F-NCM) samples. All peaks can be
indexed to the hexagonal α-NaFeO2 structure, with the space
group R3̅m. The distinct splits of (006)/(012) and (008)/
(110) peaks indicate the formation of a well-layered structure.
The ratio of the intensities of the (003) and (104) peaks is
greater than 1.2, and c/a is high, indicating low cation mixing
and good ordering of the transition metal ions in the metal
layer. The SEM images clearly show that both samples have a
uniform particle size (100−300 nm). Generally, small particles
make Li insertion/extraction easy because of decreased Li+
diffusion. The surface area of LiNi1/3Co1/3Mn1/3O2 synthesized
using a sol−gel method is large, which improves the
electrochemical performance. The regenerated material disperses well without addition of a chelating agent.
The cycling performances of R-NCM and F-NCM at 0.2 C,
0.5 C, and 1 C are shown in Figure 10a−c. The reversible
discharge capacity of R-NCM is 142.6 mA h g−1 at 0.2 C after
70 cycles, 138.2 mA h g−1 at 0.5 C after 100 cycles, and 128.3
mA h g−1 at 1 C after 100 cycles. F-NCM achieves 136.8 mA h
g−1 at 0.2 C after 70 cycles, 125.4 mA h g−1 at 0.5 C after 100
cycles, and 109.8 mA h g−1 at 1 C after 100 cycles. The
regenerated LiNi1/3Mn1/3Co1/3O2 clearly gives a higher
discharge capacity and has the highest capacity retention
(95.2% at 0.2 C, 96.0% at 0.5 C, and 94.5% at 1 C) under the
same conditions. The rate capacities of the samples were
investigated by charging the cells at 0.2 C and discharging them
at various current rates (0.2−5 C), as shown in Figure 10d. The
discharge capacities of R-NCM are 151.6, 145.7, 138.3, 129.7,
and 120.6 mA h g−1 at 0.2 C, 0.5 C, 1 C, 2 C, and 5 C,
respectively. After cycling at 5 C, the discharge capacity
recovers to 148 mA h g−1, indicating that the regenerated
material has a superior rate capability. The electrochemical
reactions of the samples were further investigated based on the
charge/discharge profiles for different cycles and EIS tests
(Figure 10e,f). The plateaus of the charge/discharge curves
occur at around 3.8 V. Long charge/discharge curve plateaus
improve the electrode stability and reversibility. Figure 10f
shows that the charge-transfer resistance of R-NCM (Rct =
58.78 Ω) is lower than that of F-NCM (Rct = 70.02 Ω), which
indicates better Li intercalation/deintercalation kinetic properties. This is because the ratio of the intensities of the (003) and
(104) peaks of R-NCM (I003/I104 = 1.469) is greater than that
of F-NCM (I003/I104 = 1.415), indicating low cation mixing and
good ordering of the transition metal ions in the metal layer in
R-NCM. Meanwhile, Al or Mg compounds are usually doped
or coated in commercial NCM cathode.
■
AUTHOR INFORMATION
Corresponding Author
*E-mail: chenrj@bit.edu.cn.
ORCID
Renjie Chen: 0000-0002-7001-2926
Notes
The authors declare no competing financial interest.
■
ACKNOWLEDGMENTS
The experimental work of this study was supported by the
Chinese National 973 Program (2015CB251106), the Joint
Funds of the National Natural Science Foundation of China
(U1564206), and the Major achievements Transformation
Project for Central University in Beijing and Beijing Science
and Technology Project (D151100003015001).
■
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■
CONCLUSION
A hydrometallurgical method was developed for recycling
LiNi1/3Co1/3Mn1/3O2 cathode active materials in spent LIBs.
The results show that the concentration of lactic acid, S/L ratio,
temperature, amount of H2O2, and leaching time have
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Bioleaching of metals from spent lithiu…