Polysulfide Regulation by the Zwitterionic Barrier toward Durable Lithium-Sulfur Batteries

Article abstract of DOI:10.1021/jacs.9b13303

Rational regulation on polysulfide behaviors is of great significance in pursuit of reliable solution-based lithium-sulfur (Li-S) battery chemistry. Herein, we develop a unique polymeric zwitterion (PZI) to establish a smart polysulfide regulation in Li-S batteries. The zwitterionic nature of PZI integrates sulfophilicity and lithiophilicity in the matrix, fostering an ionic environment for selective ion transfer through the chemical interactions with lithium polysulfides (LiPS). When implemented as a functional interlayer in the cell configuration, PZI empowers strong obstruction against polysulfide permeation but simultaneously allows fast Li⁺ conduction, thus contributing to significant shuttle inhibition as well as the resultant facile and stable sulfur electrochemistry. The PZI-based cells realize excellent cyclability over 1000 cycles with a minimum capacity fading rate of 0.012% per cycle and favorable rate capability up to 5 C. Moreover, a high areal capacity retention of 5.3 mAh cm^-2 after 300 cycles can be also obtained under raised sulfur loading and limited electrolyte, demonstrating great promise in developing high-efficiency and long-lasting Li-S batteries.

Full text of DOI:10.1021/jacs.9b13303

Subscriber access provided by Gothenburg University Library
Article
Polysulfide regulation by zwitterionic barrier
towards durable lithium-sulfur batteries
Gaoran Li, Fei Lu, Xiaoyuan Dou, Xin Wang, Dan Luo, Hao Sun, Aiping Yu, and Zhongwei Chen
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.9b13303 • Publication Date (Web): 29 Jan 2020
Downloaded from pubs.acs.org on January 30, 2020
Just Accepted
“Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted
online prior to technical editing, formatting for publication and author proofing. The American Chemical
Society provides “Just Accepted” as a service to the research community to expedite the dissemination
of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in
full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully
peer reviewed, but should not be considered the official version of record. They are citable by the
Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore,
the “Just Accepted” Web site may not include all articles that will be published in the journal. After
a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web
site and published as an ASAP article. Note that technical editing may introduce minor changes
to the manuscript text and/or graphics which could affect content, and all legal disclaimers and
ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or
consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W.,
Washington, DC 20036
Published by American Chemical Society. Copyright © American Chemical Society.
However, no copyright claim is made to original U.S. Government works, or works
produced by employees of any Commonwealth realm Crown government in the course
of their duties.

Page 1 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
Polysulfide regulation by zwitterionic barrier towards durable lithium-
sulfur batteries
7
8
9
Gaoran Li,1 Fei Lu,1,2 Xiaoyuan Dou,1 Xin Wang,3* Dan Luo,1 Hao Sun,4 Aiping Yu,1
Zhongwei Chen1*
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
1 Department of Chemical Engineering, Waterloo Institute of Nanotechnology, University
of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1 Canada
2 College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal
University, Jinan 250014, P. R. China
3
International Academy of Optoelectronics at Zhaoqing, South China Academy of
Advanced Optoelectronics, South China Normal University, Guangdong 510631, China
4
Institute of Functional Material Chemistry, Faculty of Chemistry, National & Local
United Engineering Lab for Power Battery, Northeast Normal University, Renmin Street
5268, Changchun, Jilin 130024, People's Republic of China
ABSTRACT: Rational regulation on polysulfide behaviors is of great significance in
pursuit of reliable solution-based lithium-sulfur (Li-S) battery chemistry. Herein, we
develop a unique polymeric zwitterion (PZI) to establish a smart polysulfide regulation in
Li-S batteries. The zwitterionic nature of PZI integrates sulfophilicity and lithiophilicity in
the matrix, fostering an ionic environment for selective ion transfer through the chemical
interactions with lithium polysulfides (LiPS). When implemented as a functional interlayer
in cell configuration, PZI empowers strong obstruction against polysulfide permeation but
simultaneously allows fast Li+ conduction, thus contributing to significant shuttle
inhibition as well as the resultantly facile and stable sulfur electrochemistry. The PZI-based
cells realize excellent cyclability over 1000 cycles with a minimum capacity fading rate of
0.012 % per cycle and favorable rate capability up to 5 C. Moreover, high areal capacity
retention of 5.3 mAh cm-2 after 300 cycles can be also obtained under raised sulfur loading
and limited electrolyte, demonstrating a great promise in developing high-efficiency and
long-lasting Li-S batteries.
1
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 2 of 23
1
2
3
4
5
6
INTRODUCTION
7
8
9
Lithium-sulfur (Li-S) batteries present one of the most promising solutions to high-
efficiency and cost-effective energy storage.1-3 Yet despite their intriguing virtues such as
high energy density and low cost, the fulfillment of reliable sulfur electrochemistry is
perplexed by several intractable challenges that give rise to unsatisfactory practical
capacity and cyclability.4,5 Among them, the “shuttle effect” epitomizes the most
distinguishing characteristic of Li-S batteries as compared to conventional Li-ion
chemistries. Triggered by their strong solvation in ether-based electrolyte, the highly
mobile lithium polysulfides (LiPS) perform continuous round-trip diffusion between
cathode and anode along with their chemical and electrochemical participations in both
electrode reactions, leading to severe sulfur loss, electrode passivation and coulombic
inefficiency.6-8
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Targeting this issue, aggressive strategies have been proposed capable of completely
eliminating the polysulfide shuttling through the employment of non-solvating electrolyte
or rigorous spatial/covalent-constraint sulfur electrodes, which contribute to the “solid-
based” instead of the conventional “solution-based” sulfur electrochemical reaction
mechanism.9-11 While the merits of stability and safety are convincing, solid sulfur
electrochemistry suffers from sluggish electron/ion transfers with resultant kinetic
degradation, and is still in its early infancy struggling with energy inefficiency, cost issue,
and industrial compatibility.12,13 In this respect, the solution-based counterpart involves
sulfur solid-liquid phase conversions and chemical equilibriums, leading to continuous
exposure of electron/ion-accessible interfaces and uniformization of sulfur distribution.14-
16
As a result, the solution-based sulfur electrochemistry is more accessible to superior
sulfur utilization, rate capability and energy density, as well as favorable scalability and
compatibility to current battery industry for near-future commercial implementations.17-19
Nevertheless, rational polysulfide regulation that fosters these strengths and circumvents
the detrimental shuttle effect is requisite for the success of solution-based Li-S batteries.
2
ACS Paragon Plus Environment

Page 3 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
Considering that the shuttle effect originates from the dual behaviors, i.e., dissolution and
diffusion of polysulfides, selective regulation that allows the dissolution but resists the
diffusion behavior could serve as an ideal approach to managing the advantages and
disadvantages of solution-based sulfur electrochemistry. Following this concept, the
construction of functional interlayer between cathode and separator emerges as the most
pertinent countermeasure and attracts intense research enthusiasm worldwide.20,21 The
rationale behind this strategy lies in the interactive behaviors between interlayer materials
and polysulfides, which can be generally classified into two categories, i.e., adsorbing and
repelling mechanisms. The former employs multifarious adsorbents such as carbon
materials, polar inorganics, and their composites, to physically or chemically capture and
reutilize sulfur species, so as to enhance sulfur utilization and simultaneously suppress their
migration.22-24 However, the adsorbing interlayers generally suffer from limited
adsorbability and porous architecture, which degrade the polysulfide-blocking effect
particularly under low-absorbent-dosage and high-sulfur-loading conditions. As for the
latter mechanism, the interlayers are specifically designed to chemically/electrostatically
repel the polysulfide anions and restrain the active species within the cathode, which can
be represented by functional polymers such as Nafion and inorganics such as VOPO4.25,26
These designs deliver good capability of sulfur confinement due to the ion selective
instincts, yet are still haunted by the sluggish Li+ conduction in the dense blocking matrix
with a resultant deterioration in redox kinetics. Therefore, the establishment of advanced
interlayer that concurrently fulfills efficient polysulfide blockage and facile Li+ transfer
remains challenging but significant in pursuit of reliable solution-based sulfur
electrochemistry.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
In this contribution, a unique polymeric zwitterion (PZI) was developed for rational
polysulfide regulation in Li-S batteries. Prepared by a facile and highly processible
copolymerization, the PZI combines sulfophilic and lithiophilic moieties by covalently
tethering the imidazolium cation and sulfonate anion within the alkyl- and alkoxy-based
matrix. The interactive chemistry between PZI and LiPS was investigated by a series of
experimental and computational characterizations. Polysulfide anions serve as electron
donor to be anchored on the imidazole rings, while Li+ preferably intimates to the sulfonate
3
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 4 of 23
1
2
3
4
5
6
7
8
9
terminals in the polymeric framework, thus contributing to the enhancement of LiPS
dissociation, facilitation on Li+ conduction and constraint on polysulfide diffusion. When
implemented as interlayer, these interactions enable an in-situ formation of polysulfide-
concentrated shield that strongly obstructs the polysulfide penetration but simultaneously
allows a facile Li+ transfer in solution-based Li-S configuration. Attributed to these
favorable features, cells based on PZI interlayer realize excellent cyclability with minimum
capacity fading rate of 0.012 % per cycle upon long-term 1000 cycles, decent rate
capability of 718.4 mAh g-1 at 5 C, and high areal capacity retention of 5.3 mAh cm-2 after
300 cycles at raised sulfur loading and limited electrolyte. These results demonstrate the
great superiorities of the as-developed PZI in polysulfide regulation, offering a new
pathway towards reliable solution-based sulfur electrochemistry and high-performance Li-
S batteries.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
RESULTS AND DISCUSSION
Synthesis and Characterization. The polymeric zwitterion (PZI) was prepared through a
free radical copolymerization process. 3-(1-vinyl-3-imidazolio) propanesulfonate (VIPS)
was firstly synthesized via the ionization reaction according to our previous reports (Figure
1a).27,28 Subsequently, the PZI membrane was obtained by copolymerizing VIPS and
poly(ethylene glycol) methyl ether methacrylate (PEGMEM) in a home-made mould with
poly(ethyleneglycol) dimethacrylate (PEGDMA) and 2-hydroxy-2-methylpropiophenone
as cross-linker and photo-initiator, respectively (Figure 1b, see details in Experimental).
Benefiting from the facile and processable fabrication, the PZI membrane can be well
controlled in size and thickness. The successful co-polymerization was confirmed by
Fourier transform infrared spectroscopy (FTIR) as shown in Figure S1. The disappearance
of C=C stretching vibration at 1655 cm-1 confirms the p-bond opening and the addition
polymerization to form the alkyl skeleton, while the emergence of new peaks at 1109 and
1730 cm-1 corresponding respectively to C-O-C and C=O vibrations verifies the grafting
of alkoxy and ester groups in the resultant polymeric matrix.29,30 The thermal properties of
the obtained PZI were examined by thermogravimetric analysis (TGA) and differential
scanning calorimetry (DSC). As shown in Figure S2a, PZI maintains thermally stable till
250 oC. Meanwhile, the DSC result reveals a Tg around -50 oC and no observable melting
4
ACS Paragon Plus Environment

Page 5 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
point for PZI (Figure S2b), which ensures its thermal stability and good ion mobility within
regular battery operation temperature range.31
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 1. synthesis of (a) MIPS or VIPS, and (b) PZI; (c) schematic illustration of the
functional groups and the ion selectiveness of PZI membrane
Figure 1c schematically depicts the functional structures in PZI membrane. The as-
developed PZI delivers an alkyl skeleton, which favors a structural robustness with good
mechanical and chemical stabilities. Apart form that, the alkoxy chains endow PZI with
considerable flexibility as well as good compatibility/wettability to the ether-based
electrolyte, which facilitates the Li+ transfer within the matrix.32 More importantly, the
copolymerization establishes unique zwitterionic structures with covalently anchored
cationic imidazole rings and anodic sulfonic terminal groups within the PZI network.
Zwitterions with covalently tethered ion pairs have been well recognized in regulating
specific ion mobility, which provide a unique ionic environment for effectively managing
the ion transfer behaviors.33 Beyond that, zwitterion could also serve as a unique solvent
with large dipole moment for enhancing the disassociation of the solute and facilitating the
conduction of the target ion.34 In our case, these unique features are designed to impose
regulative interactions with LiPS in purpose of a concurrent realization of desirable
polysulfide confinement and facile Li+ conduction in Li-S batteries.
Interactions between zwitterion and LiPS. 1H NMR and 7Li NMR spectra were collected
in methanol-d4 solution to investigate the interactions between the zwitterion and LiPS. It
5
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 6 of 23
1
2
3
4
5
6
7
8
9
should be noted that all the NMR spectra were collected by using an analogous monomeric
structure, i.e., 3-(1-methyl-3-imidazolio) propanesulfonate (MIPS), to represent PZI
considering their identical zwitterionic structure (Figure 1) and the poor solubility of PZI
in methanol. Meanwhile, Li2S4 was employed as the representative LiPS for NMR analysis.
Figure 2a presents the proton assignment in 1H NMR spectra. In drastic contrast to pristine
MIPS, the Li2S4@MIPS composite witnesses a vanishment of the resonance peak assigned
to Ha (highlighted in blue background in Figure 2a and amplified in Figure 2b). This
variation can be attributed to the incorporation of polysulfide that neutralizes the imidazole
ring in MIPS and intensifies the acidity of Ha. Consequently, Ha tends to be deuterated by
methanol-d4 solution, leading to this peak vanishment in the spectrum.35 Moreover, clear
upfield shifts can be observed for the resonation peaks of imidazole proton Hb and Hc when
MIPS is composited with Li2S4 (highlighted in orange background in Figure 2a and
amplified in Figure 2c). This could be induced by the electrostatic coupling between
cationic imidazole ring and anionic polysulfide, which increases of the electron cloud
density of the carbon atoms in imidazolium and accordingly intensifies the shielding
effect.36 In addition, the proton in methanol hydroxy (highlighted in green background in
Figure 2a and amplified in Figure 2d) undergoes a downfield shift in the Li2S4@MIPS
spectrum due to the formation of “lithium bonding”-like interaction between Li2S4 and
methanol.37 Figure 2e shows the variation of 7Li chemical shift before and after composite
with zwitterion. With the addition of MIPS, the 7Li resonance of Li2S4 exhibits a downfield
shift from -0.114 to -0.082 ppm, suggesting the intensification of shielding effect on Li+
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
-
via the possible formation of SO3 -Li+ pairing.38 Such interaction is expected to facilitate
the Li+ transfer by strengthening the dissociation and ionization of LiPS due to the high
-
donor capability of -SO3 to Li+. These results cooperatively demonstrate the strong
interactions between the zwitterions and LiPS through the formation of two pairs of cation-
anion couples, i.e., imidazole(+)-polysulfide(-) and lithium ion(+)-sulfonate(-),
conforming to the electrostatic attractions and Lewis acid-base interaction principles.
6
ACS Paragon Plus Environment

Page 7 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 2. (a) 1H NMR spectra of MIPS and Li2S4@MIPS composite; amplified 1H NMR
spectra of the (b) blue, (c) orange and (d) green regions for MIPS and Li2S4@MIPS
composite; (e) 7Li NMR spectra of Li2S4 and Li2S4@MIPS composite.
The chemical interactions are also supported by FTIR analysis as shown in Figure S3. The
Li2S4@MIPS composite imposes a significant peak shift for the S=O vibration in MIPS
-
from 1038 to 1061 cm-1, which signifies the coupling between -SO3 and Li+ in line with
the NMR results.28,39 Moreover, the peaks assigned to the ring breathing of imidazole (1211
cm-1), C=C (1471 cm-1) and C=N stretching (1576 cm-1) vibrations in MIPS also undergo
considerable shifts after composite with Li2S4, suggesting the strong inter-attraction
between cationic imidazole and anionic polysulfide.40,41 Apart from that, X-ray
photoelectron spectroscopy (XPS) analysis was performed to further study the interactive
chemistry between zwitterion and LiPS. As shown in Figure 3a, the N 1s spectrum of MIPS
shows a single peak at 401.6 eV due to the orbital conjugation on the imidazole ring.42
Notably, this peak shifts to a lower binding energy range after composite with Li2S4,
indicating the increase of electron cloud density in the imidazole ring due to its
coordination with the electron-rich polysulfide anion. The Li 1s spectra of Li2S4 and
Li2S4@MIPS show a consistent peak at 54.6 eV assigned to the Li-S bonding (Figure 3b).
However, the Li2S4@MIPS composite witnesses a new peak emerging at 55.4 eV attributed
7
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 8 of 23
1
2
3
4
5
6
7
8
9
to the formation of Li-O bonding, which further confirms the interaction between Li+ and
- 43
-SO3 . Figure 3c depicts the chemical states of sulfur element in different samples. MIPS
shows a typical S 2p spectrum of sulfonate group with two sub peaks locating at 166.6 and
167.8 eV. Meanwhile, Li2S4 shows typically two pairs of peaks corresponding to the
-1
0
terminal sulfur (ST ) at 161.6 eV and bridging sulfur (SB ) at 163.1 eV, respectively.44 It is
worth noting that these characteristic peaks shift to higher binding energies for the
Li2S4@MIPS composite ascribed to the coordination between sulfonate and Li+ as well as
polysulfides and imidazolium cation, which decrease the electron cloud density in sulfur.45
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 3. (a) N 1s, (b) Li 1s and (c) S 2p XPS spectra of MIPS, Li2S4 and Li2S4@MIPS
composite; optical images of (d) LiPS solution and (e) PZI membrane before and after
adsorption test; geometrically stable configurations (left) and electron density distributions
(right) of (f) Li2S4, (g) MIPS and (h) Li2S4@MIPS composite.
Given this, the interactions between zwitterion and LiPS was visualized through a direct
adsorption characterization by immersing the as-prepared PZI membrane into 0.1 M
Li2S4/(DME+DOL) solution for 24 hrs. As shown in Figure 3d, the pristine LiPS solution
exhibits a typical dark brown color, while a clear and light orange solution was obtained
after adsorption by PZI along with the membrane changing from transparent to dark brown
8
ACS Paragon Plus Environment

Page 9 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
(Figure 3e). This result optically verifies the great LiPS adsorpability of PZI via the strong
chemical interactions, which is capable of resisting a considerable concentration gradient
as demonstrated by the color contrast between the solution and membrane after adsorption.
Beyond these experimental evidences, the interactive behaviors between zwitterion and
LiPS were also explored by theoretical calculations. Figure 3f, g and h depict the
geometrically stable configurations of Li2S4, MIPS and Li2S4@MIPS composite,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
2-
respectively. The stable composite system can be achieved with the S4 anion adsorbed
onto the imidazolium cation, while the Li+ coordinates with the -SO3- terminal through a
S-Li-O “lithium bond”-like bridging,37 contributing to a high adsorption energy up to ca. -
44.87 kcal mol-1. The two Li-O bond distances are ca. 1.808 and 1.916 Å, respectively,
confirming the formation of Li-O bond in consistent with the XPS result. Meanwhile, the
distances between the adjacent S and the N in the imidazole ring are 3.349 and 3.456 Å
respectively, which also validates the chemical/electrostatic attraction between the cationic
imidazole and anionic polysulfide. These interactive behaviors can be also described by
the electron density distribution (Figure 3f-h), where the electron-rich domain (red) couples
with the electron-lean domain (blue) following the Lewis acid-base theory. Accordingly,
the electron density difference pattern further uncovers the electron transfers from the
anionic polysulfide and sulfonate to the cationic imidazole and Li+, respectively (Figure
S4). These results are highly consistent with the above spectral characterizations, which
evidentially describe the interaction mechanism between the as-developed zwitterion and
LiPS. In addition, the geometrically stable configurations, electron distributions, electron
density differences and binding energies between MIPS and other soluble LiPS, i.e., Li2S6
and Li2S8, are also presented in Figure S5, which demonstrate the good commonality of
the PZI-LiPS interactions upon the Li-S battery chemistry. When employed as interlayer
in battery configuration, these interactions are expected to rigidly anchor the early-leached
polysulfides and establish a high-concentration barrier against the penetration of
subsequent polysulfides, while simultaneously offering a favorable Li+ conduction.
Consequently, a desirable polysulfide regulation can be implemented to overcome the
stubborn shuttle issue while retaining the intriguing merits of solution-based sulfur
electrochemistry.
9
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 10 of 23
1
2
3
4
5
6
7
8
9
Polysulfide obstruction and Li+ conduction. For a proof-of-concept, the PZI interlayer
was constructed via the direct polymerization on conventional polypropylene-based
separator (denoted as PZI@PP). As shown in Figure 4a, the scanning electron microscope
(SEM) image of pristine PP membrane shows a typical porous surface. By contrast, a
smooth and non-porous surface can be observed for the PZI@PP membrane, suggesting
the good spreading of dense PZI layer (Figure 4b). Further surface characterization reveals
a smaller contact angle of 14.5o for electrolyte drop on PZI@PP than that on pristine PP
(26.3o) membrane (Figure 4a-b, bottom), indicating the superior affinity of PZI to
electrolyte, which is favorable to the electrolyte infiltration and Li+ transfer. The backside
of PZI@PP separator remains the porous surface, suggesting the mainly one-side coating
(Figure S6). The cross-section observation in Figure 4c determines the ultrathin PZI layer
of ~0.2 μm (mass loading: ca. 0.434 mg cm-2; the authentic PZI thickness could be slightly
larger due to the partial precursor infiltration in PP separator), which is intentionally
controlled under multiple considerations including i) lowering the absolute resistance for
Li+ transfer, ii) minimizing the active sulfur loss by adsorption and iii) reducing the offset
in energy density at cell level. In order to examine the polysulfide regulation, the PZI@PP
membrane was subject to a visual simulation of polysulfide diffusion, where LiPS solution
(0.2 M Li2S4/DME+DOL) and blank solvent were separated by PP or PZI@PP membrane
in a H-type cell (Figure 4d). It should be noted that the relatively high LiPS concentration
and low PZI loading were employed to neglect the color variation induced by direct LiPS
entrapment in PZI. With pristine PP separator, the opposite chamber witnesses a distinct
change from colorless to light orange after 6 h, and further into dark brown after 48 h,
signifying that polysulfide species can easily diffuse through the porous separator and give
rise to serious shuttle effect in the corresponding Li-S cells. By contrast, the as-developed
PZI@PP separator enables a clear and colorless solution even after 48 h, confirming its
great capability of blocking polysulfide diffusion. Such excellent polysulfide obstruction
originates from the strong chemical interactions between PZI and LiPS as evidenced above,
which immobilizes LiPS and establishes a robust barrier against the subsequent polysulfide
penetration. This admirable feature is expected to effectively inhibit the shuttling behaviors
and stabilize the Li-S battery chemistry.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
10
ACS Paragon Plus Environment

Page 11 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 4. Top-view SEM images and electrolyte contact angles on (a) PP and (b) PZI@PP
membranes; (c) cross-section image of PZI@PP membrane; (d) polysulfide diffusion
comparison in H-type cells with PP and PZI@PP separators; (e) ionic conductivities of
neat PZI, PZI in electrolyte and PZI in LiPS-contained electrolyte.
Apart from polysulfide blockage, Li+ conduction property is another criterion for rational
interlayer construction in Li-S batteries. Eligible polysulfide obstruction need be
established without sacrificing the Li+ conductivity to guarantee a decent sulfur reaction
kinetics. In view of this, the Li+ conduction within the PZI matrix was investigated in
different conditions as shown in Figure 4e. The as-developed PZI delivers a fair intrinsic
o
conductivity of 1.21×10-5 S cm-1 at 30 C due to the strong dipolar interaction between -
-
SO3 and Li+, high donor number of ethoxy unit to Li+, and decent Li+ solvation by the lean
DEM/DOL incorporated in the matrix. After fully soaked by electrolyte, PZI exhibits a
significantly enhanced conductivity up to 8.89×10-4 S cm-1 (30 oC), which is close to that
of pure electrolyte, confirming its good electrolyte wettability and facile Li+ permission.
Apart from that, the Li+ conduction in PZI was further examined in LiPS-contained (0.2 M
Li2S4) electrolyte to simulate the condition upon battery operation. The result shows an
even higher conductivity of 1.26×10-3 S cm-1 (30 oC), manifesting the expedite Li+ transfer
11
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 12 of 23
1
2
3
4
5
6
after LiPS adsorption, which favors the facile and stable sulfur reactions combined with a
strong polysulfide regulation. Beyond that, this desirable combination in PZI was further
+
characterized by Li+ transference number (tLi ), which was measured in 0.2 M
7
8
9
Li2S4/(DME+DOL) electrolyte with lithium foil as symmetric electrodes. Based on the
chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) results
(Figure S7), a favorably higher tLi+ ca. 0.94 can be achieved for PZI@PP compared with
that of pristine PP separator (ca. 0.59), confirming the great capability of PZI in blocking
polysulfide permeation while simultaneously allowing fast Li+ transfer. Such ionic sieve is
expected to efficiently inhibit the shuttle effect and retain a fast sulfur reaction kinetics.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Electrochemistry of PZI-based Li-S batteries. In view of the above results, the as-
developed PZI@PP separator was implemented in Li-S coin cells to examine its practical
effects on battery performance. Simple sulfur/carbon (S/C) composite was prepared as the
cathode active material (see details in Experimental). SEM observation and element
mapping confirm the uniform sulfur distribution in the composite (Figure S8). The sulfur
content was determined ca. 79.8 wt.% by TGA as shown in Figure S9. Additionally, the
electrochemical stability of PZI was verified before the battery evaluation as shown in
Figure S10. The CV profile clearly reveals the good electrochemical stability of PZI,
showing negligible current response within the potential range of 1.5 to 3.0 V (vs. Li/Li+,
hereafter inclusive), which covers the voltage range for regular Li-S battery operation.
Additionally, the linear sweep voltammetry (LSV) signifies the relatively extended
oxidative and reductive limits for PZI-electrolyte, demonstrating the good electrochemical
stability of the electrolyte system (Figure S11). Figure 5a depicts the galvanostatic charge-
discharge profiles of Li-S cell with PZI@PP separator. A typical two-plateau discharge
curve can be observed. The upper plateau at 2.35 V corresponds to the reduction of element
sulfur into long-chain soluble LiPS (Li2Sn, 4≤n≤8), while the lower plateau at 2.1 V is
assigned to further sulfur reduction into insoluble Li2S2/Li2S.46 A considerable capacity
decrease can be perceived from 1st to 2nd cycle, which could be ascribed to the sulfur loss
by LiPS dissolution as well as their adsorption by the PZI interlayer. However, subsequent
fading was effectively retarded with high capacity retention at 200th and 300th cycles. It is
also worth noting that the voltage profile well maintains upon 300 cycles with negligible
12
ACS Paragon Plus Environment

Page 13 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
polarization aggravation, indicating the good reaction kinetics and stabile sulfur
electrochemistry.
7
8
9
The CV result echoes well with the voltage profile, showing two cathodic peaks and an
overlapped anodic peak as presented in Figure 5b. Similarly, the CV curves witness a
declined current response at 2nd cycle, but well maintains the profile upon the initial several
cycles, suggesting a favorable electrochemical reversibility. Cycling performance was
compared between cells with pristine PP and PZI@PP separators at C/5 rate (1C=1675 mA
g-1) as shown in Figure 5c. The PZI@PP cell shows an initial capacity of 1279.6 mAh g-1,
which decreases to 1095.6 mAh g-1 at 2nd cycle due to the LiPS dissolution in electrolyte
and adsorption by PZI. After that, the capacity stabilizes and maintains at 1031.3 mAh g-1
after 300 cycles. In comparison, the PP cell shows relatively higher capacity than that with
PZI@PP at initial several cycles, which could be attributed to, on the one hand, the
relatively higher Li+ conductivity of pure electrolyte as reflected by the smaller
electrochemical resistance (Figure S12). On the other hand, the absence of sulfur loss by
PZI adsorption also partially contributes to the slower capacity fading at initial stage.
Nevertheless, the PP-based cell suffers from continuous capacity degradation to 808.2 mAh
g-1 at 100th cycle, presenting a drastic contrast to the stable cycling behavior in PZI-based
configuration. The significant enhancement of cell cyclability benefits from the as-
constructed PZI interlayer, which establishes, despite a slight sulfur sacrifice, a highly
effective polysulfide barrier against their penetration, thus constraining the active species
within the cathode to be efficiently utilized instead of being continuously consumed by the
shuttle effect.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
13
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 14 of 23
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Figure 5. (a) Voltage profiles and (b) CV curves of PZI@PP cells at different cycles; (c)
cycling comparison between PP and PZI@PP cells at C/5 under sulfur loading of 2.2 mg
cm-2; (d) voltage profiles of PZI@PP cell at different current rates; (e) multi-rate
performance comparison between PP and PZI@PP cells; (f) long-term cycling
performance of PZI@PP cell at 1C; (g) cycling comparison between PP and PZI@PP cells
at C/5 under sulfur loading of 4.5 mg cm-2; (h) prolonged cycling performance of PZI@PP
cell at C/10 under sulfur loading of 5.8 mg cm-2.
To understand the cyclability improvement by PZI interlayer, in situ UV-vis spectra were
collected upon the first discharge in H-type cells with different separators. The absorbances
at 330 and 430 nm-1 were highlighted as typical responses of LiPS in UV-vis spectra.47,48
As shown in Figure S13, these responses in cathode chamber undergo similar evolution
along with the depth of discharge (DOD) in PP and PZI@PP cells, conforming to the
variation of LiPS concentration in electrolyte. This indicates the similar cathode reaction
behaviors in these two configurations. Whereas in anode chamber, PZI@PP separator
14
ACS Paragon Plus Environment

Page 15 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
enables a consistently negligible absorbance in distinct comparison with the continuous
LiPS increase in PP-based cell, strongly validating the effective sulfur confinement by PZI
interlayer upon the practical Li-S battery operation. Moreover, the EIS variations upon the
cycling were also recorded as shown in Figure S14. The typical Nyquist plot of cycled Li-S
cell shows two suppressed semicircles at high and medium frequency ranges, which are
assigned to the interfacial (Rint) and charge transfer (Rct) resistances, respectively. The
intercept at real axis corresponds to the solution resistance (Rs), while the slope at low
frequency presents the Warburg resistance.49 It can be clearly noticed that the PZI@PP
separator enables a more stable and lower resistances for all the Rs, Rint and Rct upon the
cycling, manifesting the facilitated and stabilized sulfur electrochemistry attributed to the
rational polysulfide regulation.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The effective shuttle inhibition was further determined by the cycling comparison in
electrolyte without LiNO3. Generally, LiNO3 is a classic electrolyte additive which forms
robust and protective solid electrolyte interphase (SEI) layer on anode surface against the
detrimental attacks from polysulfides.50 Hence, the cycling behavior without LiNO3 is a
well-acknowledged indicator of shuttle severity in Li-S cells. As shown in Figure S15a,
PZI@PP enables superior cyclability with higher capacity retention, and more importantly,
higher and more stable coulombic efficiency than those with PP separator over 50 cycles.
In addition, a significantly smaller shuttle current can be also obtained for PZI@PP cell,
which strongly confirms its significant inhibition on shuttle effect (Figure S15b). Apart
from that, post-mortem SEM and Energy Dispersive X-ray Spectroscopy (EDX) was
performed on anode surface to further study the shuttling behavior in different
configurations. As shown in Figure S16, the Li surface with PZI@PP separator shows
comparatively an intact and smooth surface, while apparent cracks and dendrites can be
observed for that with PP separator. In addition, the EDX spectrum reveals a lower sulfur
content on Li surface in PZI@PP cell, manifesting the limited detrimental reactions from
shuttle effect (Figure S17). Moreover, the PZI@PP separator delivers an orange round spot
at cathodic side in contrast to the both clean and white sides of pristine PP separator after
cycling and washing by DME/DOL, further demonstrating the significantly stronger sulfur
immobilization by PZI (Figure S18). Furthermore, as another important shuttle indicator,
15
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 16 of 23
1
2
3
4
5
6
7
8
9
the self-discharge behavior was also examined for different cells. As shown in Figure S19a,
the PZI@PP cell exhibits a significantly higher and steadier open circuit voltage (OCV)
compared with its PP counterpart upon 72 h resting after 5 pre-cycles. This confirms the
excellent polysulfide obstruction by PZI barrier, which limits the polysulfide accessibility
to Li anode and their direct reactions, thus mitigating the voltage degradation and the
irreversible capacity loss as revealed in Figure S19b and c. All these results consistently
demonstrate the excellent suppression of polysulfide shuttling and the stabilization of
sulfur electrochemistry by the as-constructed PZI barrier.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The rate performances of different cells were also examined as presented in Figure 5d. The
PP cell suffers from a serious capacity degradation along with the increase of current rate,
resulting in a capacity of 510.8 mAh g-1 at 5 C. By contrast, the PZI@PP separator fulfills
a good rate capability with a high capacity of 718.4 mAh g-1 at 5 C, which recovers to
1082.9 mAh g-1 as switched back to C/2, manifesting the highly reversible and expedite
sulfur redox reactions. The kinetic virtue also gains strong support from the voltage profiles
at different rates, where the discharge curve well maintains the two-plateau profile even at
a high rate up to 5 C (Figure S20). Given the above results, a long-term cycling evaluation
was conducted for PZI@PP cell at 1 C as shown in Figure 5f. A favorable capacity retention
of 828.5 mAh g-1 can be maintained after a prolonged 1000 cycles, corresponding to a
minimum capacity fading rate of 0.012 % per cycle since the 2nd cycle. It should be noted
that these electrochemical performances are highly competitive among the recent
literatures with various separator engineering (Table S1). These results strongly illustrate
the great superiority of PZI in facilitating and stabilizing sulfur electrochemistry towards
high-performance Li-S batteries.
To explore the practical viability of the as-developed PZI@PP separator, raised sulfur
loadings were implemented to examine the regulation effect under polysulfide-flooding
condition as well as pursuing higher energy density. Figure 5g presents the cycling
comparison between high-loading sulfur electrodes (4.5 mgS cm-2) with different separators.
Contrastively, PZI@PP enables a much higher areal capacity retention of 4.0 mAh cm-2
after 140 cycles. More importantly, the PZI@PP cell maintains a high and stable coulombic
16
ACS Paragon Plus Environment

Page 17 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
efficiency upon the cycling, whereas the PP counterpart suffers from low and fluctuant
efficiency ascribed to the riotous polysulfide shuttling. This distinct comparison strongly
confirms the highly effective polysulfide regulation by PZI even under a high-loading
7
8
9
configuration. In addition, varied sulfur loadings and electrolyte to sulfur (E/S, mL g-1 )
S
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
ratios were investigated for PZI-based cells. Generally, highest possible sulfur loading and
lowest possible E/S ratio are desired in pursuit of high energy density at cell level, whereas
the practical implementation is always frustrated by the consequent deteriorations in sulfur
utilization and reaction kinetics.51 As shown in Figure S21, a continuous enhancement in
areal capacity can be obtained along with the increase of sulfur loading, although some
level of degradation in sulfur utilization and cycling stability can be perceived ascribed to
the increasing challenges regarding the mechanical integrity and electron/ion transfer.52
But still, a high areal capacity of 7.85 mAh cm-2 can be obtained under a raised sulfur
loading up to 8.2 mg cm-2, demonstrating that a decent sulfur electrochemistry is available
even under high sulfur loading in the PZI-based configuration.
Figure S22 depicts the discharge profiles and cycling performances of PZI@PP cells under
different E/S ratios. As a delicate but critical index in solution-based Li-S battery chemistry,
E/S ratio requires to be rationally managed to ensure facile sulfur conversions while
retaining high energy density at cell level. It can be perceived that a clear two-plateau
discharge profile can be still achievable at a low E/S ratio of 3, indicating the decent
reaction kinetics even with relatively lean electrolyte. However, continuous reduction of
both the discharge plateau potential and areal capacity can be also observed along with the
decrease of E/S ratio, signifying the aggravation of electrochemical polarization and
reaction resistance induced by the increase of polysulfide concentration, degradation of
electrolyte conductivity, limited sulfur solid-liquid phase conversion, etc.53,54 Based on
these results, a modest sulfur loading of 5.8 mg cm-2 and E/S ratio of 7 were employed for
rate and prolonged cycling evaluation. The result shows considerable capacity of 3.82 mAh
cm-2 and well-maintained multi-stage profile under a high rate up to 2 C, confirming the
decent reaction kinetics in PZI-based high-loading configuration (Figure 5g and Figure
S23). Meanwhile, the PZI@PP cell also exhibits an excellent cycling stability with a high
capacity of 5.3 mAh cm-2 after 300 cycles corresponding to a favorable capacity retention
17
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 18 of 23
1
2
3
4
5
6
7
8
9
of 82.2 % (Figure 5h). Besides, a constantly high coulombic efficiency can be maintained
over the cycling, indicating the efficient and stable sulfur electrochemistry attributed to the
rational polysulfide regulation. These results are also highly competitive among the
recently reported high-loading performances based on interlayer designs (Table S2), which
further demonstrates the intriguing potential of the as-developed PZI interlayer in pursuit
of high-performance and practically-viable Li-S batteries.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
CONCLUSIONS
In summary, a unique polymeric zwitterion was developed for rational polysulfide
regulation towards high-energy and durable Li-S batteries. The as-developed PZI
covalently anchors the sulfophilic and lithiopholic sites in the polymeric framework,
empowering strong polysulfide immobilization and facile Li+ conduction simultaneously.
When implemented as interlayer in Li-S configuration, PZI establishes a robust polysulfide
barrier that selectively obstructs the polysulfide penetration while allowing decent Li+
transfer through the separator, thus contributing to inhibited shuttle effect and stabilized
Li-S battery chemistry. Benefiting from these attributes, significantly improved cyclability
over 1000 cycles and rate capability up to 5 C can be achieved for simple S/C composite
electrode. Moreover, commendable areal capacity and cycling stability are also accessible
under high sulfur loading and limited electrolyte. This work paves a new pathway toward
rational polysulfide regulation and highly stable solution-based sulfur electrochemistry,
holding a great promise in promoting the future development of practical Li-S batteries.
ASSOCIATED CONTENT
Supporting Information
Experimental details and supplemental physicochemical, electrochemical and
computational results (FTIR, TGA, DSC, EIS, UV-vis, etc.) data are included within SI.
This material is available free of charge via the Internet at http://XXXX.
AUTHOR INFORMATION
Corresponding Authors
18
ACS Paragon Plus Environment

Page 19 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
zhwchen@uwaterloo.ca
wangxin@scnu.edu.cn
7
8
9
Notes
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
The authors declare no competing financial interest.
ACKNOWLEDGEMENTS
The authors would like to acknowledge the financial support from the Natural Sciences
and Engineering Research Council of Canada (NSERC), National Natural Science
Foundation of China Program (No. 51602111), Xijiang R&D Team (X. W.) and University
of Waterloo.
REFERENCE
(1)
Dunn, B.; Kamath, H.; Tarascon, J. M., Electrical energy storage for the grid: a battery of
choices. Science 2011, 334, 928.
(2)
Bruce, P. G.; Freunberger, S. A.; Hardwick, L. J.; Tarascon, J. M., Li-O2 and Li-S batteries
with high energy storage. Nat. Mater. 2011, 11, 19.
(3)
Batteries and fuel cells for emerging electric vehicle markets. Nat. Energy 2018, 3, 279.
(4) Manthiram, A.; Fu, Y. Z.; Chung, S. H.; Zu, C. X.; Su, Y. S., Rechargeable lithium-sulfur
batteries. Chem. Rev. 2014, 114, 11751.
(5) Ji, X. L.; Lee, K. T.; Nazar, L. F., A highly ordered nanostructured carbon-sulphur cathode
for lithium-sulphur batteries. Nat. Mater. 2009, 8, 500.
(6) Yin, Y. X.; Xin, S.; Guo, Y. G.; Wan, L. J., Lithium-sulfur batteries: electrochemistry,
materials, and prospects. Angew. Chem. Int. Ed. Engl. 2013, 52, 13186.
(7) Lang, S. Y.; Xiao, R. J.; Gu, L.; Guo, Y. G.; Wen, R.; Wan, L. J., Interfacial Mechanism
Cano, Z. P.; Banham, D.; Ye, S. Y.; Hintennach, A.; Lu, J.; Fowler, M.; Chen, Z. W.,
in Lithium-Sulfur Batteries: How Salts Mediate the Structure Evolution and Dynamics. J. Am.
Chem. Soc. 2018, 140, 8147.
(8)
carbon nanocages for high‐rate and long‐cycle lithium–sulfur batteries. Adv. Mater. 2016, 28, 9539.
(9) Xin, S.; Gu, L.; Zhao, N. H.; Yin, Y. X.; Zhou, L. J.; Guo, Y. G.; Wan, L. J., Smaller sulfur
molecules promise better lithium-sulfur batteries. J. Am. Chem. Soc. 2012, 134, 18510.
(10) Han, F. D.; Yue, J.; Fan, X. L.; Gao, T.; Luo, C.; Ma, Z. H.; Suo, L. M.; Wang, C. S., High-
Zhang, J.; Yang, C. P.; Yin, Y. X.; Wan, L. J.; Guo, Y. G., Sulfur encapsulated in graphitic
performance all-solid-state lithium-sulfur battery enabled by a mixed-conductive Li2S
nanocomposite. Nano Lett. 2016, 16, 4521.
(11)
cathodes based on PAN sulfur composites. J. Am. Chem. Soc. 2015, 137, 12143.
(12) Manthiram, A.; Yu, X. W.; Wang, S. F., Lithium battery chemistries enabled by solid-state
electrolytes. Nat. Rev. Mater. 2017, 2, 16103.
(13) Guo, J. C.; Yang, Z. C.; Yu, Y. C.; Abruna, H. D.; Archer, L. A., Lithium-Sulfur Battery
Wei, S. Y.; Ma, L.; Hendrickson, K. E.; Tu, Z. Y.; Archer, L. A., Metal-sulfur battery
Cathode Enabled by Lithium-Nitrile Interaction. J. Am. Chem. Soc. 2013, 135, 763.
19
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 20 of 23
1
2
3
4
5
6
7
8
9
(14)
Li, G. R.; Wang, S.; Zhang, Y. N.; Li, M.; Chen, Z. W.; Lu, J., Revisiting the role of
polysulfides in lithium-sulfur batteries. Adv. Mater. 2018, 30, 1705590.
(15) Peng, H. J.; Huang, J. Q.; Liu, X. Y.; Cheng, X. B.; Xu, W. T.; Zhao, C. Z.; Wei, F.; Zhang,
Q., Healing High-Loading Sulfur Electrodes with Unprecedented Long Cycling Life: Spatial
Heterogeneity Control. J. Am. Chem. Soc. 2017, 139, 8458.
(16)
Liu, F.-Q.; Wang, W.-P.; Yin, Y.-X.; Zhang, S.-F.; Shi, J.-L.; Wang, L.; Zhang, X.-D.;
Zheng, Y.; Zhou, J.-J.; Li, L., Upgrading traditional liquid electrolyte via in situ gelation for future
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
lithium metal batteries. Sci. Adv. 2018, 4, eaat5383.
(17)
Mao, Y. Y.; Li, G. R.; Guo, Y.; Li, Z. P.; Liang, C. D.; Peng, X. S.; Lin, Z., Foldable
interpenetrated metal-organic frameworks/carbon nanotubes thin film for lithium-sulfur batteries.
Nat. Commun. 2017, 8, 14628.
(18)
for large-scale energy storage. Energy Environ. Sci. 2013, 6, 1552.
(19) Chen, S. R.; Dai, F.; Gordin, M. L.; Yu, Z. X.; Gao, Y.; Song, J. X.; Wang, D. H.,
Yang, Y.; Zheng, G. Y.; Cui, Y., A membrane-free lithium/polysulfide semi-liquid battery
Functional organosulfide electrolyte promotes an alternate reaction pathway to achieve high
performance in lithium-sulfur batteries. Angew. Chem., Int. Ed. 2016, 55, 4231.
(20)
for lithium-sulfur batteries. Joule 2019, 3, 361.
(21) Huang, J. Q.; Zhang, Q.; Wei, F., Multi-functional separator/interlayer system for high-
stable lithium-sulfur batteries: Progress and prospects. Energy Storage Mater. 2015, 1, 127.
(22) Lei, T. Y.; Chen, W.; Lv, W. Q.; Huang, J. W.; Zhu, J.; Chu, J. W.; Yan, C. Y.; Wu, C. Y.;
Fan, L. L.; Li, M.; Li, X. F.; Xiao, W.; Chen, Z. W.; Lu, J., Interlayer material selection
Yan, Y. C.; He, W. D.; Xiong, J.; Li, Y. R.; Yan, C. L.; Goodenough, J. B.; Duan, X. F., Inhibiting
polysulfide shuttling with a graphene composite separator for highly robust lithium-sulfur batteries.
Joule 2018, 2, 2091.
(23)
batteries. Adv. Funct. Mater. 2018, 28, 1801323.
(24) Cai, W. L.; Li, G. R.; Zhang, K. L.; Xiao, G. N.; Wang, C.; Ye, K. F.; Chen, Z. W.; Zhu,
Li, X.; Sun, X. L., Interface design and development of coating materials in lithium-sulfur
Y. C.; Qian, Y. T., Conductive nanocrystalline niobium carbide as high-efficiency polysulfides
tamer for lithium-sulfur batteries. Adv. Funct. Mater. 2018, 28, 1704865.
(25)
polysulfides towards highly-stable lithium-sulfur batteries. Energy Environ. Sci. 2014, 7, 347.
(26) He, Y.; Qiao, Y.; Chang, Z.; Cao, X.; Jia, M.; He, P.; Zhou, H., Developing a
Huang, J. Q.; Zhang, Q.; Peng, H. J.; Liu, X. Y.; Qian, W. Z.; Wei, F., Ionic shield for
“polysulfide‐phobic” strategy to restrain shuttle effect in lithium‐sulfur batteries. Angew. Chem.
2019, 58, 11774.
(27)
Lu, F.; Gao, X. P.; Doug, B.; Sun, P. P.; Sun, N.; Xie, S. T.; Zheng, L. Q., Nanostructured
proton conductors formed via in situ polymerization of ionic liquid crystals. ACS Appl. Mater. Inter.
2014, 6, 21970.
(28)
Lu, F.; Gao, X. P.; Wu, A. L.; Sun, N.; Shi, L. J.; Zheng, L. Q., Lithium-containing
zwitterionic poly(Ionic liquid)s as polymer electrolytes for lithium-ion batteries. J. Phys. Chem. C
2017, 121, 17756.
(29)
1,3-diene tail systems. Macromolecules 2000, 33, 8549.
(30) Rahman, M. T.; Barikbin, Z.; Badruddoza, A. Z. M.; Doyle, P. S.; Khan, S. A.,
Hoag, B. P.; Gin, D. L., Cross-linkable liquid crystal monomers containing hydrocarbon
Monodisperse polymeric ionic liquid microgel beads with multiple chemically switchable
functionalities. Langmuir 2013, 29, 9535.
(31)
Ma, Q.; Zhang, H.; Zhou, C. W.; Zheng, L. P.; Cheng, P. F.; Nie, J.; Feng, W. F.; Hu, Y.
S.; Li, H.; Huang, X. J.; Chen, L. Q.; Armand, M.; Zhou, Z. B., Single lithium-ion conducting
polymer electrolytes based on a super-delocalized polyanion. Angew. Chem., Int. Ed. 2016, 55,
2521.
20
ACS Paragon Plus Environment

Page 21 of 23
Journal of the American Chemical Society
1
2
3
4
5
6
7
8
9
(32)
Zhang, H.; Li, C. M.; Piszcz, M.; Coya, E.; Rojo, T.; Rodriguez-Martinez, L. M.; Armand,
M.; Zhou, Z. B., Single lithium-ion conducting solid polymer electrolytes: advances and
perspectives. Chem. Soc. Rev. 2017, 46, 797.
(33)
zwitterions derived from ionic liquids. Phys. Chem. Chem. Phys. 2018, 20, 10978.
(34) Islam, A.; Li, J. G.; Pervaiz, M.; Lu, Z. H.; Sain, M.; Chen, L. H.; Ouyang, X. H.,
Ohno, H.; Yoshizawa-Fujita, M.; Kohno, Y., Design and properties of functional
Zwitterions for organic/perovskite solar cells, light-emitting devices, and lithium ion batteries:
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
recent progress and perspectives. Adv. Energy Mater. 2019, 9, 1803354.
(35)
exchange. J. Org. Chem. 2005, 70, 1915.
(36) Shi, L. J.; Li, N.; Yan, H.; Gao, Y. A.; Zheng, L. Q., Aggregation behavior of long-chain
N-aryl imidazolium bromide in aqueous solution. Langmuir 2011, 27, 1618.
(37) Hou, T. Z.; Xu, W. T.; Chen, X.; Peng, H. J.; Huang, J. Q.; Zhang, Q., Lithium bond
chemistry in lithium-sulfur batteries. Angew. Chem., Int. Ed. 2017, 56, 8178.
(38) Soberats, B.; Yoshio, M.; Ichikawa, T.; Ohno, H.; Kato, T., Zwitterionic liquid crystals as
1D and 3D lithium ion transport media. J. Mater. Chem. A 2015, 3, 11232.
(39) Yu, Y.; Lu, F.; Sun, N.; Wu, A. L.; Pan, W.; Zheng, L. Q., Single lithium-ion polymer
electrolytes based on poly(ionic liquid)s for lithium-ion batteries. Soft Matter 2018, 14, 6313.
(40) Berthomieu, C.; Boussac, A., FTIR and EPR study of radicals of aromatic-amino-acids 4-
methylimidazole and phenol generated by UV irradiation. Biospectroscopy 1995, 1, 187.
(41) Mao, H.; Song, Y.; Qian, D. M.; Liu, D. L.; Wu, S. Y.; Zhang, Y.; Hisaeda, Y.; Song, X.
Handy, S. T.; Okello, M., The 2-position of imidazolium ionic liquids: Substitution and
M., One-step preparation of flower-like poly(styrene-co-zwitterionic ionic liquid) microspheres
with hierarchical structures for supported acidic heterogeneous catalysts. RSC Adv. 2015, 5, 91654.
(42)
Steinruck, H. P., Recent developments in the study of ionic liquid interfaces using X-ray
photoelectron spectroscopy and potential future directions. Phys. Chem. Chem. Phys. 2012, 14,
5010.
(43)
Li, G. R.; Lei, W.; Luo, D.; Deng, Y. P.; Wang, D. L.; Chen, Z. W., 3D porous carbon
sheets with multidirectional ion pathways for fast and durable lithium-sulfur batteries. Adv. Energy
Mater. 2018, 8, 1702381.
(44)
Pang, Q.; Kundu, D.; Cuisinier, M.; Nazar, L. F., Surface-enhanced redox chemistry of
polysulphides on a metallic and polar host for lithium-sulphur batteries. Nat. Commun. 2014, 5,
4759.
(45)
polysulfide mediator for lithium-sulfur batteries. Nat. Commun. 2015, 6, 5682.
(46) Li, G. R.; Lei, W.; Luo, D.; Deng, Y. P.; Deng, Z. P.; Wang, D. L.; Yu, A. P.; Chen, Z. W.,
Liang, X.; Hart, C.; Pang, Q.; Garsuch, A.; Weiss, T.; Nazar, L. F., A highly efficient
Stringed "tube on cube'' nanohybrids as compact cathode matrix for high-loading and lean-
electrolyte lithium-sulfur batteries. Energy Environ. Sci. 2018, 11, 2372.
(47)
spectroscopic study. J. Phys. Chem. Lett. 2016, 7, 1518.
(48) Chen, T.; Zhang, Z. W.; Cheng, B. R.; Chen, R. P.; Hu, Y.; Ma, L. B.; Zhu, G. Y.; Liu, J.;
Zou, Q. L.; Lu, Y. C., Solvent-dictated lithium sulfur redox reactions: an operando UV-vis
Jin, Z., Self-Templated Formation of Interlaced Carbon Nanotubes Threaded Hollow Co3S4
Nanoboxes for High-Rate and Heat-Resistant Lithium-Sulfur Batteries. J. Am. Chem. Soc. 2017,
139, 12710.
(49)
Deng, Z. F.; Zhang, Z. A.; Lai, Y. Q.; Liu, J.; Li, J.; Liu, Y. X., Electrochemical impedance
spectroscopy study of a lithium/sulfur battery: modeling and analysis of capacity fading. J.
Electrochem. Soc. 2013, 160, A553.
(50)
Zhang, S. S., Role of LiNO3 in rechargeable lithium/sulfur battery. Electrochim. Acta 2012,
70, 344.
(51)
Hagen, M.; Hanselmann, D.; Ahlbrecht, K.; Maca, R.; Gerber, D.; Tubke, J., Lithium-
sulfur cells: the gap between the state-of-the-art and the requirements for high energy battery cells.
Adv. Energy Mater. 2015, 5, 1401986.
21
ACS Paragon Plus Environment

Journal of the American Chemical Society
Page 22 of 23
1
2
3
4
5
6
7
8
9
(52)
Peng, H. J.; Huang, J. Q.; Cheng, X. B.; Zhang, Q., Review on high-loading and high-
energy lithium-sulfur batteries. Adv. Energy Mater. 2017, 7, 1700260.
(53) Chen, J. Z.; Henderson, W. A.; Pan, H. L.; Perdue, B. R.; Cao, R. G.; Hu, J. Z.; Wan, C.;
Han, K. S.; Mueller, K. T.; Zhang, J. G.; Shao, Y. Y.; Liu, J., Improving lithium-sulfur battery
performance under lean electrolyte through nanoscale confinement in soft swellable gels. Nano Lett.
2017, 17, 3061.
(54)
Yang, Y. X.; Zhong, Y. R.; Shi, Q. W.; Wang, Z. H.; Sun, K. N.; Wang, H. L.,
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Electrocatalysis in lithium sulfur batteries under lean electrolyte conditions. Angew. Chem., Int. Ed.
2018, 57, 15549.
22
ACS Paragon Plus Environment

Page 23 of 23
Journal of the American Chemical Society
1
2
3
4
TOC graphic
5
6
7
8
9
Polysulfide regulation by zwitterionic barrier towards durable lithium-sulfur
batteries
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
23
ACS Paragon Plus Environment