Electrochromic Poly(chalcogenoviologen)s as Anode Materials for High-Performance Organic Radical Lithium-Ion Batteries

Article abstract of DOI:10.1002/anie.201903152

A series of electrochromic electron-accepting poly(chalcogenoviologen)s with multiple, stable, and reversible redox centers were used as anodic materials in organic radical lithium-ion batteries (ORLIBs). The introduction of heavy atoms (S, Se, and Te) into the viologen scaffold significantly improved the capacity and cycling stability of the ORLIBs. Notably, the poly(Te-BnV) anode was able to intercalate 20 Li ions and showed higher conductivity and insolubility in the electrolyte, thus contributing to a reversible capacity of 502 mAh g^?1 at 100 mA g^?1 when the Coulombic efficiency approached 100 %. The charged/discharged state of flexible electrochromic batteries fabricated from these anodic materials could be monitored visually owing to the unique electrochromic and redox properties of the materials. This study opens a promising avenue for the development of organic polymer-based electrodes for flexible hybrid visual electronics.

Full text of DOI:10.1002/anie.201903152

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Electrochromic Poly(chalcogenoviologens) as Anode Materials
for High-Performance Organic Radical Li-Ion Batteries
Authors: Guoping Li, Bingjie Zhang, Jianwei Wang, Hongyang Zhao,
Wenqiang Ma, Letian Xu, Weidong Zhang, Kun Zhou, Yaping
Du, and Gang He
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201903152
Angew. Chem. 10.1002/ange.201903152
Link to VoR: http://dx.doi.org/10.1002/anie.201903152
http://dx.doi.org/10.1002/ange.201903152

10.1002/anie.201903152
Angewandte Chemie International Edition
COMMUNICATION
Electrochromic Poly(chalcogenoviologens) as Anode Materials
for High-Performance Organic Radical Li-Ion Batteries
Guoping Li+, Bingjie Zhang+, Jianwei Wang, Hongyang Zhao, Wenqiang Ma, Letian Xu, Weidong Zhang
Kun Zhou, Yaping Du, and Gang He*
Abstract: A series of electrochromic electron-accepting poly(chalco-
genoviologens) with multiple, stable and reversible redox centers are
reported. They were used as anodic materials in organic radical Li-ion
batteries (ORLIBs). Introduction of heavy atoms (S, Se, and Te) into
viologen scaffold significantly improved the capacity and cycling
stability of the ORLIBs. Notably, the poly(Te-BnV) anode had an
intercalation ability of 20 Li-ions and showed higher conductivity and
insolubility in the electrolyte, hence contributing to a reversible
capacity of 502 mAh g-1 at 100 mA g-1 when the Coulombic efficiency
approached 100%. To the best of our knowledge, the poly(Te-BnV)
anode has the highest reported capacity to date for a viologen-based
electrode. Based on their unique electrochromic and redox properties,
Therefore, developing novel viologen derivatives with multiple
stable redox centers and higher specific energy could
dramatically enhance the performance and expand the limits of
ORBs.[8c]
The introduction of chalcogen atoms into organic conjugated
scaffolds could enhance the compounds’ electron mobility in
terms of greater mass and polarizability.[17] However, the inherent
toxicity and shortage of the heavy chalcogenide resources may
limit their applications, developing novel chalcogenide with low
toxicity, low chalcogen content and high energy density via the
modification of functional group is necessary to balance the
toxicity and the shortage problems. Recently, our group
developed thiocarboxylate compounds for organic sodium-ion
battery electrodes and achieved high capacity and stability when
four sulfur atoms were introduced, which demonstrated the
benefit of atom substitution approach for organic batteries.[18] In
addition, we synthesized a series of novel chalcogenoviologens
by introducing different chalcogen atoms (S, Se and Te), which
flexible
electrochromic
batteries
were
fabricated,
the
charged/discharged state could be visually monitored. This work
presents a promising avenue for the development of organic polymer-
based electrodes for flexible hybrid visual electronics.
Viologens (RV2+) are electron-accepting organic molecules
based on di-quaternized 4,4’-bipyridine moieties. Using applied
voltage or direct illumination, viologens can undergo a two-step
reversible one-electron reduction with obvious color changes.
This phenomenon, commonly observed in the radical species of
viologens (RV2+ + e- ↔ RV+•; RV+• + e- ↔ RV),[1] has been
explored in electrochromic devices (ECD),[2] molecular
machines,[3] and organic batteries,[4] and so on.[5] Due to their
synthetic versatility and easy tunability of redox properties,[6]
development of the viologen-based energy storage devices has
increased dramatically over the past decades.[7] The excellent
redox properties and unique radical states of viologens make
them exceptional electrode candidates for the new generation of
energy storage devices, such as inorganic/organic Li/Na/Mg ion
batteries,[8] aqueous organic redox flow batteries,[9] organic
radical batteries,[10] lithium-oxygen battery[11] and so on.[12] As one
of the promising emerging technologies for energy storage,[13] the
ORBs have shown several advantages compared with the
previously reported inorganic[14] and polymeric materials,[15] such
as no need for rare metals, easy tunability of redox properties,
more safety, and design flexibility at the molecular level, but the
development of such batteries was still limited.[16] The reported
ORBs suffered from poor performance, e.g. low cell capacity and
stabilities, due to fewer redox states and low specific energy.
achieved multicolor conversion in ECD and presented
a
combination of photosensitizer and electron mediator in visible-
light-driven hydrogen evolution.[19] The incorporation of chalcogen
bridge resulted in rigid skeleton, stable radical states, extra redox
centers and reduced HOMO–LUMO gap. With their multiple,
stable redox properties, we have now focused on investigating
chalcogenoviologens and their more insoluble polymeric moieties,
poly(chalcogenoviologens) with low toxicity, low chalcogen
content and high energy density as anodic materials in organic
radical Li-ion batteries (ORLIBs).
To compare and contrast, benzylated viologens 2a/3a and
xylene-bridged polyviologens 4a/5a were prepared. A series of
related poly(chalcogenoviologens) 4b/4c/4d were synthesized
under similar benzylation reaction conditions (Scheme 1). Anion
exchange in 4b/4c/4d from bromide to triflate yielded dimethyl
sulfoxide-D6-soluble polymers 5b/5c/5d. The 1H upfield shift of α-
pyridine occurred from 10.30 to 9.72 ppm with the introduction of
[*]
G. Li, B. Zhang, J. Wang, H. Zhao, Prof. Dr. G. He
Frontier Institute of Science and Technology, State Key Laboratory
for Strength and Vibration of Mechanical Structures, Xi'an Key
Laboratory of Sustainable Energy Materials Chemistry, Xi’an
Jiaotong University, Xi'an, Shaanxi Province, 710054 (China)
E-mail: ganghe@mail.xjtu.edu.cn.
Prof. Dr. Y. Du
School of Materials Science and Engineering, National Institute for
Advanced Materials, Nankai University, Tianjin, 300350 (China)
These authors contributed equally to this work.
[+]
Scheme 1. Synthesis of poly(chalcogenoviologens).
This article is protected by copyright. All rights reserved.

10.1002/anie.201903152
Angewandte Chemie International Edition
COMMUNICATION
heavier atoms due to p− conjugation and increased electron
density on the bipyridine skeleton. The NMR spectroscopy and
mass spectrometry (Figures S35 and S36) showed that the
polymers 4/5 had relatively low molecular weights, with ca. 12
repeat units. TGA analysis clarified that all benzylated viologen
bromides were all stable under 200 °C (Figures S1–S3).
observed due to the accumulation of neutral species (Figure 1c);
this process corresponds to the chemical reduction with Na.
Chalcogenoviologens (2a/2b/2c/2d) and their polymers
(4a/4b/4c/4d) were tested as electrode materials in ORLIBs, due
to the notable redox and electrochromic characteristics. Their
electrochemical performances were measured using coin cells
with lithium metal as the counter electrode in a potential range of
0.001–3.0 V vs. Li/Li+.
Compared to the corresponding viologen derivatives,
poly(chalcogenoviologens) showed similar electron-accepting
characteristics,[8c] and their electrochemistry was probed via
cyclic voltammetry (CV, Figure S4, and Table S1) with respect to
Ag/AgCl/KCl reference electrode. There were two reversible one-
electron reductions due to the presence of the bipyridine skeleton.
Redox potentials of poly(chalcogenoviologens) were measured
for 5b (Ered1,1/3 = −0.61 V, Ered2,1/3 = −1.04 V, Ered3,1/3 = −1.71 V),
5c (Ered1,1/3 = −0.60 V and Ered2,1/3 = −0.95 V, Ered3,1/3 = −1.68 V),
and 5d (Ered1,1/3 = −0.58 V and Ered2,1/3 = −0.98 V, Ered3,1/3 = −1.66
V). The semi-reversible reductive wave at -1.66 V in 5d potentially
arose from totally accepting electrons of polymer chains.[8c] Due
to the increase in electron density on the chalcogen atoms from
poly(S-BnV) (4b/5b) to poly(Se-BnV) (4c/5c) to poly(Te-BnV)
(4d/5d), the reductive wave from a chalcogenophene became
The electric conductivity and solubility of the electrode
materials are the fundamental factors determining the battery
performance.[21] The electric conductivity was increased with the
introduction of the chalcogen atoms as we observed
a
progressive deepening of the color (Figures S8 and S9) and a
reduced band gap in the molecular (2a to 2d) as well as polymeric
moieties (4a to 4d). Meanwhile, DFT calculations and conductivity
tests via four probes method also confirmed this conjecture
(Figure S10). Notably, the electric conductivity of 2d (Te-BnV)
was up to 0.096 μS cm-1, which was 10 times higher than 2a/2b/2c.
As a member of the chalcogen family, heavier Te atom has
special properties compared to S and Se atoms in terms of
greater mass and polarizability; these properties are expected to
improve the electron mobilities. In terms of electrode solubility, we
found that the electrodes barely dissolved in the electrolyte in the
first two hours and slightly dissolved after 4 hours (Figure S11).
Remarkably, the solubilities of polyviologen electrodes were
greatly reduced and the electric conductivities increased
significantly (Figure S10), especially in the case of poly(Te-BnV)
anode (4d, 0.13 μS cm-1). The latter was insoluble in the
electrolyte even after 40 charge/discharge cycles (Figure S12).
The electrochemical performances of ORLIBs measured
against Li/Li+ were characterized by cyclic voltammetry (CV).
Molecular benzylated viologens (2a/2b/2c/2d) and polymers
(4a/4b/4c/4d) had similar redox states (Figures 2a, S4, S13, and
S14). The difference of CV in solution and coin cell was attributed
to the different measurement method and electrolytes. The CV in
different electrolyte and potential window showed that the redox
states in coin cells were consistent with the CV in DMF solution
using lithium hexafluorophosphate as supporting electrolyte
(Figure S4b-S4d).[8c,22] Notably, the peak height and peak area
below 1.2 V became pronouncedly enhanced from 4a to 4b to 4c
to 4d; this phenomenon occurred due to the introduction of
chalcogen atoms and the increased number of free electron pairs
of the chalcogen atoms. The latter resulted in extra lithiation
processes occurring on the chalcogen atoms, in particular on
tellurium. Kinetic calculations illustrated that the electrochemical
reaction was commanded by the synergistic effects of capacitive
processes and diffusion-limited redox reaction. Notably, in the
case of poly(Te-BnV) (4d), a 75% fraction of the total charge
came from capacity-type contribution, which signified high rate
and long cycling performance of the organic battery. This result
was exceptional compared to other analogues. Furthermore, with
an increased scan rate, the anodic peaks shifted to a higher
potential in contrast to cathodic peaks, attributing to the increased
polarization in 4d (Figure S14). The linear fits of natural logarithm
(ln) of peak current and scan rate revealed that the slopes of
anodic and cathodic peaks were close to 1.0, illustrating that the
reaction kinetics of the system 4d is mainly controlled by the
capacitance (Figure S18).[23] The discharge/charge profiles of the
molecular viologens (2a/2b/2c/2d) were similar and there was a
tiny flat of the first discharge at 1.0 V, which came from the third
reduction state‒lithiation of bipyridine skeleton (Figures 2b, 2c,
increasingly pronounced, while
a second semi-reversible
reductive wave at −2.67 V in 2d and 5d originated from the
introduction of Te atom. Heavy atom substitution in 5b/5c/5d
decreased their LUMO energy levels, therefore facilitating the
reduction reaction.
The UV–vis spectra of poly(chalcogenoviologens) were similar
to the benzylated chalcogenoviologens and consistent with the
first singlet excitation energy obtained by time-dependent DFT
(TD-DFT) calculations (Figure S5, Table S1, and Figures
S25−S34). The maximum absorptions of 5b/5c/5d in DMF were
394/419/484 nm, respectively. This red shift was accompanied by
a band gap narrowing from 3.01 (5b) to 2.79 (5c) to 2.33 eV (5d).
This result was attributed to the raised HOMO levels due to the
stronger electron-donating character of the chalcogen atoms and
reduced aromaticity of chalcogenoviologen units.
Spectroelectrochemical behaviors of 5b/5c/5d were verified via
proof-of-concept ECD, where these molecules showed similar
electrochromic phenomena (Figures S6, S7, and 1a).[20] For 5d,
with the applied potential of -0.7 V, the color gradually changed to
dark blue and the absorption in the visible region increased due
to the formation of radical species. This process resembles the
chemical reduction with Zn (Figure 1b). When the potential of -1.2
V was applied, the decreased absorption in the visible region was
Figure 1. (a) Solution-based ECD with 5d. (b) Spectroelectrochemistry of 5d for
first reduction and chemical reduction with Zn is shown as the inset. (c)
Spectroelectrochemistry of 5d for second reduction and chemical reduction with
Na is shown as the inset.
This article is protected by copyright. All rights reserved.

10.1002/anie.201903152
Angewandte Chemie International Edition
COMMUNICATION
Figure 2. (a) The cyclic voltammograms at 0.5 mV s-1 of 4a-4d. b) Galvanostatic charge/discharge curves of 2a-2d at 100 mA g-1. c) Galvanostatic charge/discharge
curves of 4a-4d at 100 mA g-1. (d) Rate capability of 4a-4d. (e) Cycle stability of 4a-4d at 100 mA g-1. (f) Schematic diagrams for the proposed electrochemical
reduction steps of 4d. (g) The first discharge potential profile of 4d at 100 mA g-1 which correspond to the insertion of 1, 2, 4, 8, 14 and 20 Li-ions. The corresponding
contribution by acetylene black was subtracted from all data.
S15, and S16). The second discharge capacities were gradually
elevated with the substitution of heavier atoms and consistent with
the CV curves (i.e., the second discharge capacities at a current
density of 100 mA g-1 of 2a: 368 mAh g-1, 2b: 368 mAh g-1, 2c:
426 mAh g-1, 2d: 474 mAh g-1). The irreversible capacities of the
first discharge were caused by the formation of solid electrolyte
interphase (SEI) layer.[24] The specific discharge capacity of 2d
reduced to 238 mAh g-1 when the Coulombic efficiency
approached 100%. All data were obtained after subtracting the
corresponding contribution by the carbon black and the electrolyte. In
Comparing the specific capacity and rate performance, Te-BnV
(2d) revealed superior properties to 2a-2c (Figure S17). This
observation is consistent with the earlier noted superior behavior
of poly(Te-BnV) 4d. Poly(chalcogenoviologens) (4a/4b/4c/4d)
had similar discharge/charge profiles to the corresponding
monomers (Figure 2a), e.g., the maximum second discharge
capacity of 684 mAh g-1 at a current density of 100 mA g-1 was
achieved for 4d (Figure 2c). This was also atypical that better
battery performances were in accompaniment with introduction of
heavier atoms (i.e., performance gradually improved from S to Se
to Te). As shown in Figure 2d, poly(Te-BnV) (4d) electrode
exhibited reversible capacities of 799, 684, 567, 463, and 366
mAh g-1 at current densities of 50, 100, 200, 500 and 1000 mA g-
1, respectively. It is worth noting that there was a retained capacity
of 252 mAh g-1 as the current density increased to 2000 mA g-1.
When the current density dropped to 50 mA g-1, a reversible
capacity (750 mAh g-1) returned even after 38 cycles. The
irreversible capacities of the first discharge and the low initial
Coulombic efficiency were caused by the lithiation of electronic
additives (carbonaceous material) and the formation of solid
electrolyte interphase (SEI) layer. The capacity decay of 4a-4d in
the initial 20 cycles was attributed to slow formation of a stable
SEI layer, which caused the low Coulombic efficiency (<100%).[24]
The initial Coulombic efficiency was improved to 97% via loading
4d on single-walled carbon nanotubes (SWNT) in polymerization
process instead of adding acetylene black (Figure S24).[16d,25] The
specific discharge capacity became stable and reached 502 mAh
g-1 when the Coulombic efficiency approached 100% (Figure 2e).
terms
of
capacity
and
cycling
stability,
poly(chalcogenoviologens), particularly for poly(Te-BnV) anode,
have moderate performances compared with inorganic and
polymeric electrodes. The capacity is even higher than some
inorganic electrodes, such as 3DGN/MOF-derived CuO
composite[26] and the stability is better than Mn3O4@B,N co-doped
graphitic nanotubes,[27] and typical polymeric radical materials,
poly(2,2,6,6-tetramethylpiperi-dinyloxyl-4-yl methacrylate) (Table
S3).[16e] The calculations of reaction free energy (ΔG) for the first
and second steps of lithium insertion in 4a/4b/4c/4d were
obtained by DFT method and showed that 4d had significantly
lower free energy than other viologen derivatives (Figure S21).[28]
The electrochemical kinetics of poly(chalcogenoviologens)
were investigated using electrochemical impedance spectroscopy
(EIS) (Figure S19). The smaller semicircle from 4a to 4d (Figure
S20b) implied that resistances of the SEI films and the charge
transfer reactions gradually ceased. The more perpendicular line
showed the capacity-type contribution increased from 4a to 4d,
which was agreement with the CV calculation. The reduced
contact and charge-transfer resistances and increased capacity-
This article is protected by copyright. All rights reserved.

10.1002/anie.201903152
Angewandte Chemie International Edition
COMMUNICATION
Figure 3. (a) The first discharge cycle of 2d; EPR spectrum when the discharge potential decreased to 2.3 V is shown as an inset. (b) 1H NMR and (c) In situ Raman
spectroscopy for initial 2d and after each of the four discharge potentials. (d) Device components of the fabricated flexible electrochromic battery. (e) In situ reflection
spectroscopy and (f) Color changes in the process of discharge from 2.6 V to 2.3 V.
1
type contribution positively correlated with the better electric
conductivity and higher capacity in heavier chalcogen-substituted
analogues. The equivalent circuit was utilized to quantify the
electrochemical kinetics (Figures S20c, and Table S2), the
charge-transfer resistance (Rct) decreased to 73.88 Ω for 4d,
electrochemical kinetics (Figures S20c, and Table S2), the
charge-transfer resistance (Rct) decreased to 73.88 Ω for 4d,
demonstrating faster charge-transfer kinetics and electric
responses.[29]
Calculations showed that one Li-ion insertion per unit of 4d
contributed to a theoretical capacity of 69.2 mAh g−1 and the
lithiation process showed that each unit was capable of accepting
20 Li-ions:[28] the initial two inserted Li-ions could be attributed to
a reduction from 4d to radical species 4d’ and reduction from 4d’
to neutral species 4d’’, respectively. Another two Li-ions could
respectively insert into two sides of Te-bipyridine due to the semi-
reversible reduction at −2.67 V (vs. Ag/AgCl) from Te atom and
two electrons in the outer layers of Te in 4d.[30] The structure after
lithiation of Te in 4d was shown in Figure S22, which was verified
by the DFT calculation, the ΔG indicated that the Li ion insertion
of Te was a spontaneous reaction.[31] The other 16 Li-ions could
be inserted by the electrochemical reaction on the unsaturated
carbons of the C5/C6 rings, as shown in Figures 2f.
of Figure 3a). The upfield shift of H resonances of the pyridine
and unshifted 1H resonances of the benzene ring were noted
along with the decrease in discharge potential (to 1.2 V); this
observation is in agreement with the formation of neutral species
2d’’ (the green line in Figure 3b). When the discharge potential
further decreased to 0.5 V, 1H resonances of the pyridine nearly
1
ceased, but H resonances of the benzene ring persisted, i.e.,
there were no more aromatic protons in the bipyridine skeleton
due to the lithiation of viologen scaffold (2d’’’, the orange line in
Figure 3b). In addition, the new signal appeared in the upfield of
1H NMR, corresponding to the completely lithiated molecule
(2d’’’’, the black line in Figure 3b, to 0.001 V).[32] The process of
lithiation was also confirmed by in situ Raman spectroscopy
(Figure 3c). The redox behavior and density functional theory
(DFT) calculations, as well as the experimental study of structural
changes of single building block (2d), commendably verified the
predicted charge/discharge and lithiation mechanism of
poly(chalcogenoviologens).
Unique
electrochromic
and
redox
properties
of
poly(chalcogenoviologens) allowed us to further develop the
“smart” battery (in which the charged/discharged states are visible)
and explore the field of flexible hybrid visual electronics.[33] In this
regard, a flexible electrochromic battery was fabricated using ITO-
coated PET as a current collector and EC gel of 4d as an
electrode material (Figure 3d). In the process of discharge from
2.6 V to 2.0 V, the color of the electrochromic battery changed to
purple and the reflectivity was significantly decreased on an entire
wavelength scale (Figures 3e and 3f). We also tested the
performance of a flexible cell using an aluminum film and a slurry
coating method (Figure S23). This flexible cell showed good
capacity and repeatability. Compared with inorganic or typical
organic electrochromic batteries, such as KFeIII[FeII(CN)6](PB)[34]
and WO3 based batteries,[35] the poly(chalcogenoviologens)-
based batteries not only show higher capacity and cycle stability,
but also possess better flexibility.
The structure of the anode and their stability during battery
operation are the determining factors of the device performance.
To investigate the Li-ion intercalation effect, the structural
changes between initial and discharged Te-BnV (2d, equivalent
1
to a building block of polymer 4d) was studied using H NMR,
electron paramagnetic resonance (EPR) and in situ Raman
spectroscopies (Figures 3a–3c) due to insolubility of
poly(chalcogenoviologens). The original 2d exhibited a singlet
and two multiplets in 1H NMR with chemical shifts of 9.98 and 9.38
and 9.28 ppm, attributed to the bipyridine skeleton. When the
discharge potential decreased to 2.1 V, the NMR signal
completely disappeared due to the generation of radical species
2d’, which were also confirmed by EPR spectroscopy (the inset
This article is protected by copyright. All rights reserved.

10.1002/anie.201903152
Angewandte Chemie International Edition
COMMUNICATION
[9] a) T. Janoschka, N. Martin, U. Martin, C. Friebe, S. Morgenstern, H. Hiller,
M. D. Hager, U. S. Schubert, Nature 2015, 527, 78-81; b) T. Janoschka, N.
Martin, M. D. Hager, U. S. Schubert, Angew. Chem. Int. Ed. 2016, 55,
14427-14430; c) T. Liu, X. Wei, Z. Nie, V. Sprenkle, W. Wang, Adv. Energy
Mater. 2016, 6, 1501449-1501449; d) B. Hu, C. DeBruler, Z. Rhodes, T. L.
Liu, J. Am. Chem. Soc. 2017, 139, 1207-1214; e) L. Fan, C. Jia, Y. G. Zhu,
Q. Wang, ACS Energy Lett. 2017, 2, 615-621; f) C. DeBruler, B. Hu, J.
Moss, X. Liu, J. Luo, Y. Sun, T. L. Liu, Chem 2017, 3, 961-978.
[10] a) A. Ghosh, S. Mitra, RSC Adv. 2015, 5, 105632-105635; b) S. Sen, J.
Saraidaridis, S. Y. Kim, G. T. R. Palmore, ACS Appl. Mater. Interfaces.
2013, 5, 7825-7830; c) S. M. Beladi-Mousavi, S. Sadaf, A. M. Mahmood, L.
Walder, ACS Nano 2017, 11, 8730-8740.
In conclusion, a series of benzylated chalcogenoviologens and
poly(chalcogenoviologens) with multiple, stable and reversible
redox centers were synthesized. These molecules revealed
excellent electron-accepting and electrochromic properties.
Based on these novel characteristics, chalcogenoviologens and
their polymers were tested as electrode materials in organic
radical Li-ion batteries. With the introduction of heavier chalcogen
atoms, the second discharge capacity and cycle stability were
enhanced dramatically, especially in the case of Te-BnV (2d).
Similarly, poly(chalcogenoviologens) showed promising high-
performance rates and long-life cycles of ORLIBs. The maximum
second discharge capacity of poly(Te-BnV) (4d) reached up to
684 mAh g-1 at a current density of 100 mA g-1 and the specific
discharge capacity became stable and reached 502 mAh g-1 when
the Coulombic efficiency approached 100%, making it the highest
reported capacity for a viologen-based electrode to date. This was
attributed to the increased electric conductivity and extra lithiation
processes on Te atom. These processes were examined in
[11] a) M. J. Lacey, J. T. Frith, J. R. Owen, Electrochem. Commun. 2013, 26,
74-76; b) L. Yang, J. T. Frith, N. Garcia-Araez, J. R. Owen, Chem. Commun.
2015, 51, 1705-1708.
[12] a) L. Cao, S. Sadaf, S. M. Beladi-Mousavi, L. Walder, Eur. Polym. J. 2013,
49, 1923-1934; b) N. Sano, W. Tomita, S. Hara, C.-M. Min, J.-S. Lee, K.
Oyaizu, H. Nishide, ACS Appl. Mater. Interfaces. 2013, 5, 1355-1361; c) M.
Yao, H. Sano, H. Ando, T. Kiyobayashi, Sci. Rep. 2015, 5, 10962; d) H. Wu,
Y. Cao, L. Geng, C. Wang, Chem. Mater. 2017, 29, 3572-3579; e) S.
Perticarari, Y. Sayed-Ahmad-Baraza, C. Ewels, P. Moreau, D. Guyomard,
P. Poizot, F. Odobel, J. Gaubicher, Adv. Energy Mater. 2018, 8, 1701988.
[13] a) Y. H. Zhu, Y. B. Yin, X. Yang, T. Sun, S. Wang, Y. S. Jiang, J. M. Yan,
X. B. Zhang, Angew. Chem. Int. Ed. 2017, 56, 7881-7885; b) R. A. Rincón,
G. Heydenrych, Batteries & Supercaps 2018, 1, 3-5; c) M. Duduta, S. de
Rivaz, D. R. Clarke, R. J. Wood, Batteries & Supercaps 2018, 1, 131-134;
d) N. Hergué, B. Ernould, A. Minoia, R. Lazzaroni, J.-F. Gohy, P. Dubois,
O. Coulembier, Batteries & Supercaps 2018, 1, 102-109; e) R. Vaidya, V.
Selvan, P. Badami, K. Knoop, A. M. Kannan, Batteries & Supercaps 2018,
1, 75-82; f) Y. H. Zhu, X. Yang, X. B. Zhang, Angew. Chem. Int. Ed. 2017,
56, 6378-6380.
details and later applied in the fabrication of
a flexible
electrochromic battery. The explored versatile and efficient
strategy offers a new platform for the development of next-
generation high-capacity radical lithium-ion battery electrodes for
flexible hybrid visual electronics.
Acknowledgements
This work was supported by the Natural Science Foundation of China
(21704081, 21875180), the Fundamental Research Funds for the Central
Universities (1191329805), Natural Science Foundation of Shaanxi province
(2018JM2026), National 1000-Plan program, and the Cyrus Chung Ying Tang
Foundation. We thank Drs. Yu Wang and Gang Chang and Axin Lu at
Instrument Analysis Center of Xi'an Jiaotong University for their assistance with
Raman spectroscopy and Elemental analysis and HRMS. We also thank Prof.
Dingxin Liu for his help with EPR measurements.
[14] a) M. Winter, B. Barnett, K. Xu, Chem. Rev. 2018, 118, 11433-11456; b) C.
Chen, X. Xie, B. Anasori, A. Sarycheva, T. Makaryan, M. Zhao, P.
Urbankowski, L. Miao, J. Jiang, Y. Gogotsi, Angew. Chem. Int. Ed. 2018,
57, 1846-1850; c) X. Chi, Y. Liang, F. Hao, Y. Zhang, J. Whiteley, H. Dong,
P. Hu, S. Lee, Y. Yao, Angew. Chem. Int. Ed. 2018, 57, 2630-2634.
[15] a) S. Muench, A. Wild, C. Friebe, B. Haupler, T. Janoschka, U. S. Schubert,
Chem. Rev. 2016, 116, 9438-9484; b) N. Wang, J. He, Z. Tu, Z. Yang, F.
Zhao, X. Li, C. Huang, K. Wang, T. Jiu, Y. Yi, Y. Li, Angew. Chem. Int. Ed.
2017, 56, 10740-10745; c) Y. Zhang, J. Duan, D. Ma, P. Li, S. Li, H. Li, J.
Zhou, X. Ma, X. Feng, B. Wang, Angew. Chem. Int. Ed. 2017, 56, 16313-
16317.
Keywords: poly(chalcogenoviologens) • multiple redox centers •
electrochromism • electrode materials • organic Li-ion batteries
[16] a) L. Bugnon, C. J. H. Morton, P. Novak, J. Vetter, P. Nesvadba, Chem.
Mater. 2007, 19, 2910-2914; b) Y. Imada, H. Nakano, K. Furukawa, R. Kishi,
M. Nakano, H. Maruyama, M. Nakamoto, A. Sekiguchi, M. Ogawa, T. Ohta,
Y. Yamamoto, J. Am. Chem. Soc. 2016, 138, 479-482; c) H. Tokue, T.
Murata, H. Agatsuma, H. Nishide, K. Oyaizu, Macromolecules 2017, 50,
1950-1958; d) K. Hatakeyama-Sato, H. Wakamatsu, R. Katagiri, K. Oyaizu,
H. Nishide, Adv. Mater. 2018, 30, 1800900; e) K. A. Hansen, J. Nerkar, K.
Thomas, S. E. Bottle, A. P. O'Mullane, P. C. Talbot, J. P. Blinco, ACS Appl.
Mater. Interfaces. 2018, 10, 7982-7988.
[1] L. A. Vermeulen, M. E. Thompson, Nature 1992, 358, 656-658.
[2] a) A. N. Woodward, J. M. Kolesar, S. R. Hall, N.-A. Saleh, D. S. Jones, M.
G. Walter, J. Am. Chem. Soc. 2017, 139, 8467-8473; b) H. Oh, D. G. Seo,
T. Y. Yun, C. Y. Kim, H. C. Moon, ACS Appl. Mater. Interfaces. 2017, 9,
7658-7665.
[3] a) Y. Li, Y. Dong, X. Miao, Y. Ren, B. Zhang, P. Wang, Y. Yu, B. Li, L.
Isaacs, L. Cao, Angew. Chem. Int. Ed. 2018, 130, 737-741; b) M. C. Lipke,
T. Cheng, Y. Wu, H. Arslan, H. Xiao, M. R. Wasielewski, W. A. Goddard, J.
F. Stoddart, J. Am. Chem. Soc. 2017, 139, 3986-3998.
[17] a) G. He, L. Kang, W. Torres Delgado, O. Shynkaruk, M. J. Ferguson, R.
McDonald, E. Rivard, J. Am. Chem. Soc. 2013, 135, 5360-5363; b) G. He,
W. Torres Delgado, D. J. Schatz, C. Merten, A. Mohammadpour, L. Mayr,
M. J. Ferguson, R. McDonald, A. Brown, K. Shankar, E. Rivard, Angew.
Chem. Int. Ed. 2014, 53, 4587-4591; c) A. J. Tilley, C. Guo, M. B. Miltenburg,
T. B. Schon, H. Yan, Y. Li, D. S. Seferos, Adv. Funct. Mater. 2015, 25,
3321-3329; d) L. Xu, G. Li, T. Xu, W. Zhang, S. Zhang, S. Yin, Z. An, G.
He, Chem. Commun. 2018, 54, 9226-9229.
[4] J. Luo, B. Hu, C. Debruler, T. L. Liu, Angew. Chem. Int. Ed. 2018, 57, 231-
235.
[5] a) Q. V. Nguyen, P. Martin, D. Frath, M. L. Della Rocca, F. Lafolet, S.
Bellinck, P. Lafarge, J.-C. Lacroix, J. Am. Chem. Soc. 2018, 140, 10131-
10134; b) C. Sun, G. Xu, X.-M. Jiang, G.-E. Wang, P.-Y. Guo, M.-S. Wang,
G.-C. Guo, J. Am. Chem. Soc. 2018, 140, 2805-2811.
[6] Y. Wu, J. Zhou, B. T. Phelan, C. M. Mauck, J. F. Stoddart, R. M. Young, M.
R. Wasielewski, J. Am. Chem. Soc. 2017, 139, 14265-14276.
[7] a) S. Sathyamoorthi, M. Kanagaraj, M. Kathiresan, V. Suryanarayanan, D.
Velayutham, J. Mater. Chem. A 2016, 4, 4562-4569; b) L. Striepe, T.
Baumgartner, Chem. Eur. J. 2017, 23, 16924-16940.
[18] H. Zhao, J. Wang, Y. Zheng, J. Li, X. Han, G. He, Y. Du, Angew. Chem. Int.
Ed. 2017, 56, 15334-15338.
[19] G. Li, L. Xu, W. Zhang, K. Zhou, Y. Ding, F. Liu, X. He, G. He, Angew.
Chem. Int. Ed. 2018, 57, 4897-4901.
[8] a) N. Kang, J. H. Park, J. Choi, J. Jin, J. Chun, I. G. Jung, J. Jeong, J.-G.
Park, S. M. Lee, H. J. Kim, S. U. Son, Angew. Chem. Int. Ed. 2012, 51,
6626-6630; b) T. Gong, X. Lou, J.-J. Fang, E.-Q. Gao, B. Hu, Dalton Trans.
2016, 45, 19109-19116; c) M. Stolar, C. Reus, T. Baumgartner, Adv.
Energy Mater. 2016, 6, 1600944; d) A. B. Ikhe, N. Naveen, K.-S. Sohn, M.
Pyo, Electrochim. Acta 2018, 283, 393-400.
[20] M. Stolar, J. Borau-Garcia, M. Toonen, T. Baumgartner, J. Am. Chem. Soc.
2015, 137, 3366-3371.
[21] Q. Zhao, Z. Zhu, J. Chen, Adv. Mater. 2017, 29, 1607007.
[22] J. Wu, X. Rui, G. Long, W. Chen, Q. Yan, Q. Zhang, Angew. Chem. Int. Ed.
2015, 54, 7354-7358.
This article is protected by copyright. All rights reserved.

10.1002/anie.201903152
Angewandte Chemie International Edition
COMMUNICATION
[23] C. Luo, G. L. Xu, X. Ji, S. Hou, L. Chen, F. Wang, J. Jiang, Z. Chen, Y. Ren,
K. Amine, C. Wang, Angew. Chem. Int. Ed. 2018, 57, 2879-2883.
[24] a) T. Sun, Z.-J. Li, H.-G. Wang, D. Bao, F.-L. Meng, X.-B. Zhang, Angew.
Chem. Int. Ed. 2016, 55, 10662-10666; b) K. A. See, M. A. Lumley, G. D.
Stucky, C. P. Grey, R. Seshadri, J. Electrochem. Soc. 2017, 164, A327-
A333; c) X. Fan, F. Wang, X. Ji, R. Wang, T. Gao, S. Hou, J. Chen, T. Deng,
X. Li, L. Chen, C. Luo, L. Wang, C. Wang, Angew. Chem. Int. Ed. 2018, 57,
7146-7150.
[25] H. Wu, Q. Meng, Q. Yang, M. Zhang, K. Lu, Z. Wei, Adv. Mater. 2015, 27,
6504-6510.
[26] D. Ji, H. Zhou, Y. Tong, J. Wang, M. Zhu, T. Chen, A. Yuan, Chem. Eng. J.
2017, 313, 1623-1632.
[27] H. Tabassum, R. Zou, A. Mahmood, Z. Liang, Q. Wang, H. Zhang, S. Gao,
C. Qu, W. Guo, S. Guo, Adv. Mater. 2018, 30, 1705441.
[28]S. Renault, V. A. Oltean, C. M. Araujo, A. Grigoriev, K. Edström, D. Brandell,
Chem. Mater. 2016, 28, 1920-1926.
[29] J. Wu, X. Rui, C. Wang, W.-B. Pei, R. Lau, Q. Yan, Q. Zhang, Adv. Energy
Mater. 2015, 5, 1402189.
[30] a) C. Han, Z. Li, W.-j. Li, S.-l. Chou, S.-x. Dou, J. Mater. Chem. A 2014, 2,
11683-11690; b) T. Koketsu, B. Paul, C. Wu, R. Kraehnert, Y. Huang, P.
Strasser, J. Appl. Electrochem. 2016, 46, 627-633; c) A. R. Park, C. M. Park,
ACS Nano 2017, 11, 6074-6084; d) X. Han, G. Qing, J. Sun, T. Sun, Angew.
Chem. Int. Ed. 2012, 51, 5147-5151.
[31] a) P.-T. Chen, F.-H. Yang, T. Sangeetha, H.-M. Gao, K. D. Huang, Batteries
& Supercaps 2018, 1, 209-214; b) T. Sun, Z.-J. Li, X.-B. Zhang, Research
2018, 2018, 1-10.
[32] D. C. Elias, R. R. Nair, T. M. G. Mohiuddin, S. V. Morozov, P. Blake, M. P.
Halsall, A. C. Ferrari, D. W. Boukhvalov, M. I. Katsnelson, A. K. Geim, K.
S. Novoselov, Science 2009, 323, 610-613.
[33] Y. Guo, W. Li, H. Yu, D. F. Perepichka, H. Meng, Adv. Energy Mater. 2017,
7, 1601623.
[34] J. Wang, L. Zhang, L. Yu, Z. Jiao, H. Xie, X. W. Lou, X. Sun, Nat. Commun.
2014, 5, 4921.
[35] a) J. Zhao, Y. Tian, Z. Wang, S. Cong, D. Zhou, Q. Zhang, M. Yang, W.
Zhang, F. Geng, Z. Zhao, Angew. Chem. Int. Ed. 2016, 55, 7161-7165; b)
X. Xia, Z. Ku, D. Zhou, Y. Zhong, Y. Zhang, Y. Wang, M. J. Huang, J. Tu,
H. J. Fan, Mater. Horiz. 2016, 3, 588-595.
This article is protected by copyright. All rights reserved.

10.1002/anie.201903152
Angewandte Chemie International Edition
COMMUNICATION
Entry for the Table of Contents (Please choose one layout)
Layout 1:
COMMUNICATION
A
new
electrochromic
poly(chalcogenoviologens)
were used as anodes to
fabricate “smart” high-
series
of
Guoping Li+, Bingjie Zhang+,
Jianwei Wang, Hongyang Zhao,
Wenqiang Ma, Letian Xu, Weidong
Zhang, Kun Zhou, Yaping Du, and
Gang He*
performance organic radical
Li-ion batteries. Introduction
of the heavy atoms (S, Se,
Page No. – Page No.
Electrochromic
and
Te)
dramatically
Poly(chalcogenoviologens) as
Anode Materials for High
Performance Organic Radical Li-
Ion Batteries
improved their capacity and
cycling stability, leading to
the discovery of the highest
reported capacity to date for
a viologen-based electrode.
This article is protected by copyright. All rights reserved.