Efficient Synthesis of 3,6-Dihydro-2H-pyrans via [3+2+1] Annulation Based on the Heteroatom-free Tri-atom Donor

Article abstract of DOI:10.1002/adsc.201900900

A new [3+2+1] annulation strategy based on the heteroatom-free tri-atom donor to synthesize 3,6-dihydro-2H-pyrans has been developed. In this method, 2-arylpropylene served as tri-atom donor to contribute three carbon atoms, the heteroatom was provided by aldehyde, and DMSO served as one carbon donor and solvent. This annulation reaction gave 3,6-dihydro-2H-pyrans in moderate to good yields. Based on the control experiments, a possible mechanism was proposed. (Figure presented.).

Full text of DOI:10.1002/adsc.201900900

Research Article
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Cite This: ACS Appl. Mater. Interfaces 2019, 11, 28801−28808
Conjugated Carbonyl Polymer-Based Flexible Cathode for Superior
Lithium-Organic Batteries
Qiang Li,† Dongni Li,† Haidong Wang,† Heng-guo Wang,*,†,‡ Yanhui Li,† Zhenjun Si,*,†
and Qian Duan*,†,‡
†School of Materials Science and Engineering, Changchun University of Science and Technology, Changchun 130022, China
‡Engineering Research Center of Optoelectronic Functional Materials, Ministry of Education, Changchun 130022, China
S
* Supporting Information
ABSTRACT: Conjugated carbonyl compounds are deemed as high
theoretical capacity and green electrode materials for lithium-ion batteries
(LIBs) but are limited by their high dissolution and poor electronic
conductivity. In this paper, we have successfully synthesized a series of
multicarbonyl conjugated polymers using the coupling polymerization
reaction and then constructed carbonyl-conjugated polymer/carbon
nanotube hybrid films by a vacuum-filtration method. Importantly, the
hybrid films could serve as a flexible, binder-free, and free-standing organic
cathode for LIBs, which could deliver a high reversible discharge capacity of
142.3 mAh g−1 at 50 mA g−1, good cycling stability with a capacity
retention of 74.6% at 500 mA g−1 after 300 cycles, and excellent rate
capability of 120.6 mAh g−1 at 1000 mA g−1. In addition, the theoretical
calculation has proved that the symmetrical conjugated structure can well
accommodate four Li+ ions during the electrochemical reaction. Interestingly, the assembled full cell and flexible battery can
power the small devices, suggesting its potential to use in bendable or wearable energy-storages devices.
KEYWORDS: conjugated carbonyl polymer, organic cathode materials, flexible electrode, coupling polymerization,
lithium-organic batteries
valid strategy to suppress the dissolution problem.27,28
Generally, the formation of polymers is realized by combining
1. INTRODUCTION
Lithium-ion batteries (LIBs) have been emerged as the most
electrochemical active monomer with some inactive linker
promising energy storage devices for applying in smart grids,
groups, such as methylene,23 imine,22 and thioether groups.29
portable electronics, electric vehicles, and large-scale energy
storage systems.1−3 However, the commercial LIBs are focused
Although the dissolution problem of organic compounds could
be greatly improved, the increase weight of inactive moieties
on inorganic electrode materials, which are almost obtained
will decrease their theoretical capacity. Therefore, using the
from nonrenewable mineral resources and their manufactures
are often associated with huge energy cost and environment
pollution. Furthermore, the intrinsic properties of inorganic
materials would limit their specific capacities and cause safety
cross-coupling method to directly construct C−C coupled
conjugated carbonyl polymers without additional linker groups
may be an ideal strategy to exploit high-performance organic
problems.4−6 Thus, it is necessary to develop sustainable and
electrode materials for LIBs. However, there still exists the
inherent defect of poor electronic conductivity for organic
environmentally friendly electrode materials to meet the
growing demand of green energy.7−10
Compared with those of inorganic materials, organic
electrode materials have many overwhelming advantages,
materials. As a response, the incorporation of carbon materials,
such as graphene and carbon nanotubes (CNTs), is an efficient
tactic to improve the conductivity of organic active materials.
Moreover, the carbon matrix endows organic compound-based
composite materials with a flexible feature, which could be
served as a free-standing electrode without using a binder, a
conductive additive, and a metal current collector. This flexible
electrode can not only simplify the manufacturing operation of
the conventional electrodes but also enhance the battery
including high specific capacity, low cost, small environment
pollution, and abundant resources.11−15 Until now, conjugated
carbonyl organic compounds such as quinones,16,17 anhy-
drides,18,19 and ketones18,20 have been emerged as the most
hopeful organic electrode materials because of their redox
stability, structure diversity, multielectron reactions, and fast
reaction kinetics.21,22 However, these organic compounds also
show high dissolution in organic electrolytes, which results in
fast capacity attenuation during cycling.23−26 From the
perspective of molecular engineering, polymerization is a
Received: April 12, 2019
Accepted: July 17, 2019
Published: July 17, 2019
© 2019 American Chemical Society
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Figure 1. Schematic of the synthesis route for the PPT/PPQ-based flexible and free-standing film.
CNTs were first dispersed into ethanol (20 mL) and then the mixture
was sonicated for 2 h to form a uniform suspension. Finally, the
suspension was loaded on a microfiltration membrane (0.22 μm
poly(vinylidene fluoride) microporous membrane) through a vacuum
filter. After drying at 70 °C under vacuum, a flexible and self-standing
film was obtained. Herein, different samples were prepared by
adjusting different mass ratios of polymers to CNTs (1:1, 1:2, and
1:3), which were denoted PPTC-1, PPTC, and PPTC-3. For
comparison, the PQ-based film was prepared by the same method,
which was denoted PPQC. In addition, the bare CNT electrode was
directly prepared through a vacuum filter without adding active
materials.
2.3. Electrochemical Characterization. The electrochemical
performance was examined using CR2025 coin half-cells that contain
lithium foil as an anode, a Celgard 2400 membrane as separator, 1 M
LiTFSI dissolved in a mixed solvent of 1,3-dioxolane and dimethoxy-
ethane (1:1, vol %) as an electrolyte, and the binder-free and free-
standing films as a cathode (the electrodes were cut into disks with a
diameter of 12 mm and the mass loading of 0.49−0.73 mg cm−2 of the
active material). For comparison, the traditional working electrodes
were composed of active material, acetylene black, and poly-
(vinylidene fluoride) (3:6:1 or 8:1:1). The slurry was grinded over
1 h by adding NMP as the solvent, which was then uniformly adhered
onto the Al foil and dried at 70 °C for 24 h. All of the batteries were
assembled in an argon-filled glovebox.
performance including the increased energy/power densities
and the enhanced safety problems, which can promote the
rapid expansion of flexible electronic devices.30,31 Therefore, it
is imperative to construct C−C coupled conjugated carbonyl
polymer-based free-standing and flexible electrode for efficient
lithium-organic batteries.
Herein, we have successfully synthesized a series of
conjugated carbonyl polymers by a one-step organometallic
polycondensation reaction and then constructed flexible and
free-standing conjugated carbonyl polymer/CNT hybrid films
(PPTC) through the easy vacuum-filtration method. Two
types of conjugated carbonyl polymers, including poly(pyrene-
4,5,9,10-tetraone) (PPT) and poly(9,10-phenanthrenequi-
none) (PPQ), were synthesized using the cross-coupling
method without additional inactive linker groups, which avoids
the increase of molecular weight and extends the conjugated
structure of molecule, thus showing a higher capacity and
reduction potential. Furthermore, the incorporation of CNTs
endows the hybrid films with a flexible feature, which could be
served as a flexible, binder-free, and free-standing organic
electrode for LIBs. To study the effect of Li coordination on
the chemical structure, the energy levels and electronic
distribution of lithiated PT and PQ are also calculated by
density functional theory (DFT). As a result, a hybrid flexible
electrode consisting of PPT with four carbonyl groups (PPTC)
shows superior electrochemical performance compared to that
of PPQ with two carbonyl groups (PPQC).
3. RESULTS AND DISCUSSION
The synthetic process of the PPT/PPQ-based flexible films is
schematically shown in Figure 1. First, the symmetrical/
asymmetrical conjugated carbonyl compounds of PT/PQ with
four/two carbonyl groups are chosen as the unique structural
unit of polymerization due to their conjugated structure and
high theoretical capacity (409/260 mAh g−1). In fact,
organometallic polycondensation based on the C−C coupling
reaction, e.g., Ni(0) complex catalyzes dehalogenation
polycondensation reactions of dihaloaromatic compounds
nX−Ar−X + nNiLm → −(Ar)n− + nNiX2Lm, where X
represents a halogen, L represents a ligand, and Ar represents
an aromatic ring, has been demonstrated as an effective
method to directly prepare conjugated polymers.32−35 Herein,
two types of conjugated carbonyl polymers are synthesized
using the C−C coupling reaction catalyzed by Ni(COD)2 as
the catalyst (detailed synthesis and characterization of these
compounds are shown in the Supporting Information).
Subsequently, the as-prepared PPT/PPQ is mixed with the
CNTs by sonication and then the easy vacuum-filtration
2. EXPERIMENTAL SECTION
2.1. Synthesis of Poly(pyrene-4,5,9,10-tetraone) (PPT). PPTs
were synthesized according to the reported method.32,33 First,
Ni(COD)2 (2 mmol, 550 mg), bipyridine (BPY, 2 mmol, 312 mg),
and 1,5-cyclooctadiene (COD, 1.5 mmol, 135 μL) were dissolved in
20 mL of dimethylformamide (DMF). Then, the solution containing
PT-2Br (1.5 mmol, 633 mg) and 10 mL of DMF was added into the
above solution dropwise. All of the above experiments were operated
in a N2-filled glovebox. Finally, the assembled reactor was sealed and
kept at 60 °C for 7 days. After the reaction, the solution was poured
into a 50 mL mixture of diluted HCl (1 M) and methanol (1:1, v/v)
and then the deep brown precipitate was filtrated and washed with 1
M HCl, H2O, and methanol. Finally, the products were further
purified by dissolving in DMF and recrystallized by injecting
methanol.
2.2. Preparation of the Flexible and Free-Standing Film. To
fabricate a PPT-based flexible and free-standing film, the PPT and
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Figure 2. (a) FT-IR spectra and (b) XRD patterns of CNTs, PT, PPT, and PPTC. (c) Raman spectra of CNTs and PPTC. (d) Thermogravimetric
curves of PT, PPT, and PPTC under a N2 atmosphere.
Figure 3. SEM images of (a) CNTs and (b, c) PPTC. (d) Photograph of the flexible free-standing PPTC film. (e) Stress−strain curves of CNTs
and PPTC.
method is applied to construct the PPT/PPQ-based flexible
film. Herein, the strong π−π interaction between conjugated
carbonyl compounds and CNTs promotes the formation of a
flexible film and further suppresses the dissolution of the
conjugated carbonyl polymers.
ize the structure of various samples. In Figure 2a, the
characteristic peaks for CO and CC of PPT show an
obvious shift and become broader compared to those for PT
monomer, indicating the formation of polymers. In addition,
the existence of the peaks from the polymers in PPTC shows
the formation of the hybrid films and the absence of spectral
changes for PPT and PPTC indicates the noncovalent
functionalization between PPT and CNTs. The change of
the crystal structure is investigated by the X-ray diffraction
(XRD) (Figure 2b). The existence of many sharp diffraction
peaks manifest that PT has an obvious crystalline structure. In
1
The structures of various samples are first confirmed by H
NMR and UV−vis absorption spectra (Figures S1−S5).
Intuitively, the PPT and PPQ show insolubility compared to
that of the monomers PT and PQ in different solvents (Figure
S6), which confirm the formation of the polymers. Fourier
transform infrared (FT-IR) spectroscopy is used to character-
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Figure 4. (a) CV curves of PPTC at 0.2 mV s−1. (b) Galvanostatic discharge/charge curves and (c) cycling performance of PPTC at 50 mA g−1.
(d) Cycling performance at 500 mA g−1 and (e) rate performance at different current densities of PPTC and PPQC. (f) Nyquist plots of different
samples.
contrast, the PPT shows a lower diffraction intensity,
indicating the amorphous structure. Furthermore, the PPTC
has similar peaks to those of PPT and CNTs, indicating the
formation of hybrid films. Raman spectra is used to further
investigate the chemical properties of the hybrid film (Figure
2c). Two typical peaks at 1340 (D band) and 1581 cm−1 (G
band) are observed, whose ratio (ID/IG) can be used to
evaluate the disorder and graphitization degree of carbon
materials.36 Compared with the CNTs, the PPTC shows the
increased intensity ratio of ID/IG, indicating the higher disorder
degree and defect structure, which is in consistence with XRD
patterns. The thermal stability of various samples is also
characterized (Figure 2d). For PT, the first weight loss at 120
°C is attributed to the loss of solvent. Then, the structure is
decomposed at 300 °C and the remained weight is 5.31 wt %.
For PPT, the decomposition of PPT takes place at 420 °C and
the retained weight is 25.93 wt %, which is attributed to the
large planar ring of the PT unit and the extended rigid polymer
chain.32 In contrast, the PPTC shows the highest remained
weight of 82.17 wt % even at 1000 °C. These results show that
the hybrid films show superior thermal stability at elevated
temperatures, which is beneficial for enhancing the safety as a
cathode material for LIBs. In addition, the PPQ-based samples
have also been characterized, which confirm the successful
preparation of PPQC (Figures S7−S10).
The morphologies of various samples are investigated by
scanning electron microscopy (SEM). It is obvious that the PT
monomer shows a well-defined rectangular shape, while the
PPT polymer shows irregular microparticles, suggesting their
increased disorder degree after polymerization (Figure S11).
Furthermore, the surface morphology of free-standing PPTC is
investigated. As shown in Figure 3a, the CNT bundles tangle
together to form an interconnected network with the smooth
surface. In contrast, the PPTC film shows the morphology of
long CNT-interconnected networks covered by PPT polymer
particles (Figure 3b,c). When the concentration of the PPT
polymer is increased, some PPT polymer particles can be
clearly observed; however, when the concentration of the PPT
polymer is decreased, majority of CNT-interconnected net-
works can be clearly observed (Figure S12). Interestingly, the
CNTs in the PPTC film could be served as the current
collector. It is well known that the CNTs possess high
electrically conductivity and mechanically robust; thus, the
PPTC film can be directly served as a self-standing flexible
electrode with good flexibility (Figure 3d). Furthermore, the
dynamic mechanical analysis is used to examine the mechanical
properties of the PPTC film. The stress−stain curves show that
the tensile strength for the pure CNTs is 0.45 MPa with 3.7%
stain, while for the PPTC film, it is 1.97 MPa with 1.96% stain
(Figure 3e). Their Young’s moduli are calculated to be 0.012
and 0.101 GPa, respectively. The excellent mechanical
performance shows exciting potential in organic-based
bendable or wearable energy-storages devices.30
The electrochemical performance of the samples is
investigated as a working cathode for LIBs. Typically, cyclic
voltammetry (CV) curves of samples are measured from 1.5 to
3.5 V (Figures 4a and S13). As observed, PT, PPT, and PPTC
all show two main couples of redox peaks, which are attributed
to two-stage successive lithiation/delithiation of the four
carbonyl groups. In contrast, the redox potentials of PPT
and PPTC are higher than those of PT (3.07/3.25 and 2.19/
2.46 V for PPT, 3.1/3.17 and 2.29/2.54 V for PPTC, and
2.95/3.2 and 1.83/2.4 V for PT), demonstrating that the
extended conjugated structure can obviously enhance the
redox potential.10,37,38 Also, PPTC shows higher redox
potentials than those of PPQC, which is attributed to the
multicarbonyl conjugated structure.10 In addition, PPTC
shows additional two couples of weak redox peaks, which
may be attributed to the greater utilization of redox-active sites
resulting from the incorporation of the highly conductive
CNTs.30,31 Interestingly, PPTC shows the almost overlapping
CV profiles, indicating good reversibility. Figure 4b presents
the galvanostatic discharge/charge (GDC) curves of PPTC at
50 mA g−1. Due to the two-step lithiation/delithiation process
of carbonyl groups, there are two discharge plateaus at 3.11
and 2.42 V and two charge plateaus at 3.22 and 2.56 V, which
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tally with the CV curves. Also, PPTC exhibits high initial
discharge capacity of 146.3 mAh g−1. In addition, PPTC also
shows high reversible discharge specific capacity of 142.5 mAh
g−1 with the Coulombic efficiency as high as ∼100% after 70
cycles (Figure 4c). Remarkably, even at 500 mA g−1, PPTC
also shows high reversible discharge capacity of 87.2 mAh g−1
with the capacity retention of 74.6% after 300 cycles (Figure
4d); the reduced capacity may result from the partly separation
of active materials from CNTs. As a comparison, PPQC also
shows high initial discharge capacity of 73.5 mAh g−1 and has a
discharge capacity of 70.9 mAh g−1 after 300 cycles. It is
obvious that PPQC shows lower discharge/charge capacities
than those of PPTC, which can be easily understood in view of
the increased number of the carbonyl groups. In fact, the
different electrolytes also play a very crucial role in enhancing
the electrochemical property of organic electrode materials,
which has been confirmed by the reported literature works.39
Also, the high addition of acetylene black could show higher
capacities in the conventional electrode (Figure S14). In
addition, the broad potential range of 1−3.5 V could also show
higher capacities (Figure S15). Interestingly, PPT exhibits
better electrochemical performance including a higher initial
discharge capacity of 196.0 mAh g−1 at 50 mA g−1 and a
reversible discharge capacity of 209.9 mAh g−1 after 50 cycles
compared with that of PT, which may be because the extension
of the conjugated structure could increase the capacity and
enhance the stability of organic electrode materials to a certain
extent.39,40 At 200 mA g−1, PPT can also deliver a high
reversible capacity of 187.4 mAh g−1 after 300 cycles (Figure
S16a). Even at 1000 mA g−1, the high capacity of 113.9 mAh
g−1 could also be maintained (Figure S16b). On the other
hand, the content of the CNTs in the hybrid films is also
examined. It is clear to find that PPTC exhibits the optimum
cycling performance compared with that of PPTC-1 and
PPTC-3 and the CNTs show negligible capacity contribution
(Figure S17). Therefore, the active site utilization of PPT is
affected by the electrical conductivity. During the electro-
chemical reactions, the active sites on the surface of the
polymer may generate considerable capacity, but the active
sites may be covered inside the inactive polymer, which may
result in the low utilization of active site and release the low
specific capacity.20,35,41 To study the influence of additional
CNTs on fast discharge/charge processes, the rate perform-
ance of the PPTC and PPQC is shown in Figure 4e. PPTC
shows superior rate capability to that of PPQC, including
discharge capacities of 146.5, 151.3, 148.1, 148.1, and 137.1
mAh g−1 at the current densities of 50, 100, 200, 500, and 1000
mA g−1, respectively. When the current density returns to 50
mA g−1, a high capacity of 132.5 mAh g−1 can be recovered,
indicating the faster reaction kinetics and excellent reversibility
of PPTC and higher the energy density (Figure S18). To
explain the reason for superior rate capability of PPTC,
electrochemical impedance spectroscopy is measured (Figure
4f). The semicircles in the high-frequency region represent the
Rct between the electrode materials and the electrolyte
interface, which corresponds to the reaction kinetics of
electrode materials.21 Obviously, the hybrid films show smaller
Rct values than those of polymers, which could be because the
incorporation of CNTs increases the conductivity. In addition,
the Rct of PPT-based cathode materials is smaller than that of
PPQ-based cathode materials, which could be because the
extension of the conjugated structure can increase the
conductivity of organic electrode materials to a certain
extent.38 Based on these excellent features, the PPTC shows
comparable electrochemical performance to that of the
reported organic cathodes (Table S1).
To study the structure change of PPT during the Li+
intercalation/deintercalation process, ex situ FT-IR spectra
are measured. The characteristic peaks at around 1666 cm−1
for carbonyl groups become weaker after the first discharge
process and then recover as the following charge process,
indicating the reversible reaction of the carbonyl groups
(Figure S19). In addition, a similar phenomenon can also be
observed after the 10th discharge/charge process, indicating
the good stability and excellent redox activity of PPT.
According to the analyses above, the reaction mechanism of
the PT unit can be supposed to be of two steps for the storage
of four Li+ ions (Figure 5a). During the discharge process, two
Figure 5. (a) Electrochemical reaction mechanism of the PT unit. (b)
HOMO/LUMO energy levels and orbit distribution of PT and PQ.
Li+ ions are first captured by the carbonyl groups of PT, thus
forming symmetrical lithiated PT-2Li. Then, anther two Li+
ions are further captured to form PT-4Li. After the following
charge process, the Li+ ions separate from the carbonyl groups
and the PT unit with four carbonyl groups could be recovered.
The symmetry structure of PT may improve the chemical
stability and decrease the polarization effect during the redox
reaction, which can effectively improve the electrochemical
performance.10 To provide deeper insight into the different
electrochemical properties of PPT and PPQ, the energy levels
of highest occupied molecular orbital (HOMO) and the lowest
unoccupied molecular orbital (LUMO) for the PT and PQ are
calculated by density functional theory (DFT).28,42 According
to the molecular orbital theory, a molecule with a lower
LUMO energy level always has greater electron affinity and
better oxidizability, thus showing a higher reduction potential.
In contrast, PT shows a lower LUMO energy level (−3.56 eV)
than that of PQ (−2.99 eV) (Figure 5b), which confirms that
extending the conjugated structure of the molecule could lower
its LUMO energy level, thus showing greater electron affinity
and higher reduction potential.10,37,43 This result is in
agreement with the CV curves of PPTC and PPQC (Figures
4a and S13). In addition, the energy gap (Eg) between HOMO
and LUMO energy levels can be used to indicate the electronic
conduction. In contrast, PT shows smaller Eg value (−3.50 eV)
than that of PQ (−3.63 eV), which confirms that extending the
conjugated structure of molecule could narrow its energy gap,
thus showing higher electronic conduction. This result is in
agreement with the rate performance of PPTC and PPQC
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Figure 6. (a) Schematic representation and (b) discharge/charge curves of the flexible battery. (c) Schematic representation and (d) discharge/
charge curves of the full cell. Digital photographs of LED lighting by the flexible battery under different conditions (e) and lighting of different
devices by the full cell (f).
(Figure 4e). In addition, the PT also exhibits a much smaller Eg
compared to the larger Eg for most of the organic electrodes
(4.16 eV for 9,10-anthraquinone and 3.76 eV for 1,4-
benaoquinone) in previous literature works.44 After capturing
Li+ ions, the Eg values of PT-xLi (x = 2 or 4) are further
decreased (2.91 eV for PT-2Li and 2.40 eV for PT-4Li, Figure
S20), indicating the increasing chemical reactivity of PT-xLi.
Moreover, the extended conjugation can decrease the Eg value
and reduce the degree of polarization; thus, the PPTs may
exhibit excellent electrochemical performance as a cathode
material for LIBs.37 Furthermore, it is clearly seen that the
HOMO and LUMO orbits of all of the samples are mainly
distributed on their benzene ring, which may be attributed to
the effective conjugation between the aromatic ring and the
carbonyl groups.10 The above results demonstrate that the
stable and symmetrical conjugated structure of the PT unit can
promote the combination with four Li+ ions during the
electrochemical reaction.
To demonstrate the practical application of the PPTC
flexible electrode, the flexible battery and the full cell are
assembled. In Figure 6a, the PPTC flexible cathode is paired
up with the lithium foil to form the flexible battery.
Interestingly, the PPTC-based flexible battery can exhibit
high initial discharge/charge capacities of 112.7/125.8 mAh
g−1 at 50 mA g−1 (Figure 6b). Furthermore, the full cell has
been assembled through coupling PPTC with graphite (Figure
6c). In Figure 6d, the typical GDC curves show that the full
cell can exhibit the initial charge/discharge capacities of 138.7/
72.8 mAh g−1 (calculated based on the mass of PPTC).
Certainly, the electrochemical performance of the full cell
should be improved by adjusting the electrolyte, preactivating
the electrode, or changing the mass ratio of the cathode with
anode. As a proof of concept, an light-emitting diode (LED)
can be easily lighted by a flexible battery, even when the
battery is bended or processed into a simple bracelet (Figure
6e), and the full cell can power various devices, including an
electronic thermometer, an LED, and a small bike lamp
(Figure 6f).
4. CONCLUSIONS
In summary, we have synthesized a series of conjugated
carbonyl polymers including PT and PQ units using the
coupling polymerization reaction and constructed flexible,
binder-free, and free-standing PPTC and PPQC cathodes for
LIBs. The methodology not only inhibits the dissolution of
monomer and extends the conjugated structure of molecule
but also enhances the electronic conductivity of organic
materials and endows the electrode with flexible features.
When used as a flexible cathode for LIBs, the PPTC exhibits
higher discharge plateau, good Li+ storage property, and
excellent rate capability. Furthermore, the reaction mechanism
of the conjugated carbonyl polymers is also elucidated by
experimental and theoretical analyses, which demonstrate that
the multicarbonyl and symmetrical conjugated structure of the
PT unit is beneficial to improving the electrochemical
performance. Therefore, the present strategy using the
coupling polymerization reaction and vacuum-filtration
method may open up a new avenue for constructing a
conjugated carbonyl polymer-based flexible electrode with high
performance for application in bendable or wearable energy-
storages devices.
ASSOCIATED CONTENT
■
S
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acsami.9b06437.
Synthetic procedure of PT, PT-2Br, PQ-2Br and PPQ;
1H NMR data; UV−vis spectra; solubility test; detailed
characterization of PPQC; SEM images; corresponding
electrochemical tests; summary of the electrochemical
properties of organic electrode materials; ex situ FT-IR
spectra; and theoretical analyses (PDF)
AUTHOR INFORMATION
■
Corresponding Authors
*E-mail: wanghengguo@cust.edu.cn (H.-g.W.).
*E-mail: szj@cust.edu.cn (Z.S.).
*E-mail: duanqian88@hotmail.com (Q.D.).
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(18) Yuan, C. P.; Wu, Q.; Li, Q.; Duan, Q.; Li, Y. H.; Wang, H. G.
Nanoengineered Ultralight Organic Cathode Based on Aromatic
Carbonyl Compound/Graphene Aerogel for Green Lithium and
Sodium Ion Batteries. ACS Sustainable Chem. Eng. 2018, 6, 8392−
8399.
ORCID
Zhenjun Si: 0000-0001-9365-6567
Notes
The authors declare no competing financial interest.
(19) Yuan, C. P.; Wu, Q.; Shao, Q.; Li, Q.; Gao, B.; Duan, Q.; Wang,
H. G. Free-Standing and Flexible Organic Cathode based on
Aromatic Carbonyl Compound/carbon nanotube Composite for
Lithium and Sodium Organic Batteries. J. Colloid Interface Sci. 2018,
517, 72−79.
(20) Geng, J.; Bonnet, J. P.; Renault, S.; Dolhem, F.; Poizot, P.
Evaluation of Polyketones with Ncyclic Structure as Electrode
Material for Electrochemical Energy Storage: Case of Tetraketopiper-
azine Unit. Energy Environ. Sci. 2010, 3, 1929−1933.
(21) Chen, H.; Armand, M.; Demailly, G.; Dolhem, F.; Poizot, P.;
Tarascon, J. M. From Biomass to a Renewable LiXC6O6 Organic
Electrode for Sustainable Li-Ion Batteries. ChemSusChem 2008, 1,
348−355.
ACKNOWLEDGMENTS
■
This work was financially supported by the Science &
Technology Department of Jilin Province (No.
20170101177JC).
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