Three-Electron Redox Enabled Dithiocarboxylate Electrode for

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Functional Nanostructured Materials (including low-D carbon)

Three-Electron Redox Enabled Dithiocarboxylate Electrode for Superior Lithium Storage Performance Jianwei Wang, Hongyang Zhao, Letian Xu, Yaodong Yang, Gang He, and Yaping Du ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b11485 • Publication Date (Web): 25 Sep 2018 Downloaded from http://pubs.acs.org on September 28, 2018

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ACS Applied Materials & Interfaces

Three-Electron Redox Enabled Dithiocarboxylate Electrode for Superior Lithium Storage Performance Jianwei Wang,a Hongyang Zhao,c Letian Xu,a Yaodong Yang,a Gang He*a and Yaping Du*a,b a

Frontier Institute of Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi,

710054, China. b

School of Materials Science and Engineering & National Institute for Advanced Materials,

Centre for Rare Earth and Inorganic Functional Materials, Nankai University, Tianjin, 300350, China. c

School of Science, Xi’an Jiaotong University, Xi’an, Shaanxi, 710054, China.

*E-mail: [email protected], [email protected]

ABSTRACT: Organic carboxyl compounds are promising anode candidates for lithium ion batteries in which oxygen-related redox dominates the reaction mechanisms. Herein, two nanostructured

organic

electrodes

of

π-extended

naphthyl-based

dicarboxylate

and

dithiocarboxylate compounds, namely sodium naphthalene-2,6-dicarboxylate (SND) and sodium naphthalene-2,6-bis(carbothioate) (SNB) are firstly synthesized and investigated systematically for lithium ion battery. Through introducing less electronegative sulfur atoms into carboxylic groups at molecular level, SNB exhibits a different voltage profile and delivers higher reversible capacity of 280 mAh g-1 than SND (198 mAh g-1) at a current density of 50 mA g-1. A combination of electrochemical properties and DFT calculations reveals that SNB could

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reversibly store three Li+ per formula unit, while SND only stores two Li+. The present work offers a new strategy to develop redox molecules with tunable redox potentials and accommodation more alkaline ions for high performance battery systems.

KEYWORDS: Three-electron redox, Organic electrode, Lithium battery, Tunable potential, Electronic transfer, Energy storage mechanism


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1. Introduction In the last few decades, lithium ion batteries (LIBs) have achieved a great commercial success in various fields such as mobile power, portable devices, electric vehicles and smart grids, owing to their high energy and power densities.1-5 Especially, the boosting market demand for rechargeable batteries has aroused people’s attention to the economic and environmental sustainability.6-11 A typical LIB consists of graphite anode, non-aqueous electrolyte and transition metal oxide cathode. However, the energy density of conventional LIB cannot satisty the need for increasing energy consumption in modern society. Therefore, novel electrode material is urgently needed. Among the various electrode candidates, organic electrode materials have attracted increasing scientific attention recently, mainly because of their low cost, low toxicity, structural diversity, renewability and environmental friendliness.12-14 According to the redox functional groups and reaction mechanisms of organic compounds, organic electrodes mainly include carbonyl compounds,15, radical compounds,19,

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and conducting polymers.21,

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organosulfur compounds,17,

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Evidently, the capacity and voltage

profile of organic electrodes could be adjusted flexibly through the molecular engineering strategy. Aiming at higher capacity, it is expected to introduce as many lithium ions as possible in electrodes.23, 24 As for tunable voltage profile, the most popular method is to attach electronpoor/rich groups to the redox active molecule. For instance, Dunn and co-workers methodically studied a family of naphthalene diimide derivates as electroactive materials for LIBs. 25 Through changing substituents (-NMe2, -H, -F and -CN) with different electronic characteristics in the host structure of naphthalene ring, these organic materials could exhibit tunable discharge potentials between 2.3 and 2.9 V vs. Li+/Li. Shaijumon and co-workers explored the energetic structure-voltage profile correlation by tuning the dihedral angle for tetrabromo-substituted


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perylene diimide in great detail.26 Another method is to modify the aromatic structures. Chen and co-workers have designed a series of fused heteroaromatic carbonyl organic compounds. By introducing electronegative atoms (such as O, N and S) in aromatic rings, a great change in voltage profile was observed with small change in molecular weight.27 Organic compounds with dicarboxylic groups such as conjugated dicarboxylate compounds,28 sodium terephthalate,29 or dilithium 2,6-naphthalene dicarboxylate,30 have been extensively explored for rechargeable lithium/sodium ion batteries. And the results have demonstrated they reversibly intercalated two extra lithiums/sodiums per unit formula and showed a plateau in voltage profiles. However, to achieve higher specific capacities and tunable voltage profiles in dicarboxylate electrodes, it was necessary to identify organic compounds that exhibit multielectron redox capability, lighter molecular weight and different functional groups. Herein, we first synthesized the naphthyl-based dithiocarboxylate electrode through introducing the electronegative sulfur atom instead of the oxygen atom in functional groups and systematically studied electrochemical properties for advanced energy storage, compared to sodium naphthalene-2,6-dicarboxylate. During the multiple redox process, it was also very nessessary to understand associated structural evolutions of electrode materials. DFT calculations were performed to simulate the lithiation/delithation processes of two electrodes and helped us further to understand the changes of energy level and orbital evolution. Electrochemical analyses and DFT calculations showed that the sodium naphthalene-2,6dicarboxylate (SND) can reversibly store two Li+ per formula unit with corresponding capacity of 198 mAh g-1, while sodium naphthalene-2,6-bis(carbothioate) (SNB) can store three Li+ by introduction of less electronegative sulfur atoms with much higher capacity of 280 mAh g-1.


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Besides more Li+ can be accomodated in the SNB, the voltage profile was also significantly changed from a single plateau to three charge/discharge plateaus. 2. Experimental Section 2.1 Synthesis of sodium naphthalene-2,6-dicarboxylate

Dimethyl naphthalene-2,6-dicarboxylate (5 g, 20.5 mmol) and NaOH (2.09 g, 52.3 mmol) were put into 50 mL deionized water in a 100 mL round flask. Then, the mixture was heated to reflux until the suspension solution became clear completely. After that, it was cooled to room temperature, poured into a 500 mL breaker and deionized water of 250 mL was added. Concentrated hydrochloric acid was added drop-wise under stirring at room temperature, till the pH value was ~1. And then a large amount of white precipitation appeared, then was filtered, washed with water and dried under vacuum. Yield: 4.03 g (91 %). 1H NMR (400 MHz, DMSOd6): δ 13.30 (s, 2H), 8.67 (s, 2H), 8.22 (d, J = 8.5 Hz, 2H), 8.04 (dd, J = 8.6, 1.2 Hz, 2H); 13C NMR (100 MHz, DMSO-d6): δ 167.25, 134.19, 130.22, 130.14, 129.77, 125.94; IR vmax (25 °C): 2827, 1674, 1602, 1425, 1339, 1289, 1267, 1189, 913, 772 cm-1. A mixture of naphthalene-2,6-dicarboxylic acid (500 mg, 2.3 mmol) and NaOH (300 mg, 7.5 mmol) in deionized water was heated to 70 °C for 12h. The solution was cooled to room


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temperature, appropriate methanol was added, then the suspended solid appeared. The product was obtained by filtration, washed with a mixture of methanol-water and dried under vacuum. Yield: 562 mg (94 %). 1H NMR (400 MHz, D2O): δ 8.42 (s, 2H), 8.05 (d, J = 8.5 Hz, 2H), 7.96 (d, J = 8.4 Hz, 2H);

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C NMR (100 MHz, D2O): δ 175.50, 135.17, 133.75, 128.97, 128.76,

126.16; UV/vis (in H2O): λmax () = 241 nm (5.57 × 105 M-1 cm-1); IR vmax (25 °C): 1606, 1556, 1496, 1394, 1359, 1195, 1140, 1092, 926, 786 cm-1. 2.2 Synthesis of sodium naphthalene-2,6-bis(carbothioate)

2,6-Naphthalenedicarbothioic acid was synthesized by modification of a reported procedure.31 Naphthalene-2,6-dicarboxylic acid (0.86 g, 4.00 mmol), thionyl chloride (30 mL) and catalytic amount of DMF were added in a dry round bottom flask equipped with magnetic stirrer bar , then the mixture was refluxed at 70 °C for 12 h. The excess thionyl chloride was removed by rotary evaporator. The residue was washed with hexane and dried under vacuum. Yield: 0.83 g (82 %). The above crude product of naphthalene-2,6- dicarbonyl dichloride (0.25 g, 1.00 mmol) and thioacetamide (0.20 g, 2.50 mmol) were added in dry THF (30 mL) and then the mixture was stirred for 4h at room temperature. NaOH (1M, 20 mL) was slowly added to the reaction


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mixture, tetrahydrofuran was removed by reduced pressure. Next, dilute hydrochloric acid (1M, 30 mL) was added and the mixture was extracted with diethyl ether several times. The combined organic phase was dried by anhydrous Na2SO4 and removed by reduced pressure to obtain the product (2,6-naphthalenedicarbothioic acid). Yield: 0.17 g (70 %). 1H NMR (400 MHz, DMSOd6): δ 8.66 (d, J = 9.7 Hz, 2H), 8.22 (d, J = 8.5 Hz, 2H), 8.04 (d, J = 8.5 Hz, 2H); 13C NMR (100 MHz, DMSO-d6): δ 167.23, 134.18, 130.20, 130.13, 129.76, 125.93. IR vmax (25 °C): 3078, 1688, 1656, 1288, 1163, 1129, 972, 912, 853, 707cm-1. An aqueous solution (2 mL) of NaOH (40 mg, 1 mmol) was transferred to a stirred aqueous suspension (8 mL) of 2,6-naphthalenedicarbothioic acid (248 mg, 1 mmol) at room temperature. After complete reaction, the solution was filtered and then dried by a freezer-dryer to give sodium naphthalene-2,6-bis(carbothioate) as yellow solid. Yield: 257 mg (88 %). 1H NMR (400 MHz, D2O): δ 8.40 (d, J = 7.7 Hz, 2H), 8.04 (d, J = 8.5 Hz, 2H), 7.96 (t, J = 8.9 Hz, 2H);

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C

NMR (100 MHz, D2O): 168.30, 135.04, 129.23, 128.92, 128.71, 126.08. IR vmax (25 °C): 1602, 1557, 1445, 1405, 1215, 1157, 1118, 1004, 968, 840, 821, 789 cm-1. This compound decomposes without melting. UV/vis (in H2O): λmax () = 243 nm (3.02 × 105 M-1 cm-1). 3. RESULTS AND DISCUSSION 3.1. Characterization of SND and SNB Sodium naphthalene-2,6-dicarboxylate (SND) and sodium naphthalene-2,6-bis(carbothioate) (SNB) were synthesized starting from the commercially available dimethyl naphthalene-2,6dicarboxylate. The overall yields were more than 50 %. The solid powder of SND exhibited the white color while SNB turned light yellow. The remarkable changes of color indicated that oxygen atoms were replaced with sulfur atoms successfully. Two electrode materials were


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insoluble in the electrolyte (Figure S1). To confirm the formation and purity of SND and SNB, UV-vis spectroscopy (Figure S2) and nuclear magnetic resonance spectroscopy (NMR) measurements were performed (Figures S3-S10). The morphologies and thermostabilities of the prepared organic salts were further characterized with scanning electron microscope (SEM) and thermogravimetry analysis (Figure S11), respectively. The SEM showed that SND and SNB had different morphologies.

Figure 1. SEM images of (a) SND and (b) SNB. (c) FT-IR spectra of SND and SNB (attenuated total reflectance (ATR) technique). (d) XRD patterns of SND and SNB.

Figure 1a and 1b showed that the as-prepared SND powders were microrods of 0.5-1.2 μm diameters, and SNB consisted of interconnected nanosheets. The thermogravimetric investigation of two samples were conducted in the temperature range of 30-700 °C, at a heating rate of 10 K min-1 in the air. Differential thermogravimetric curves revealed that the decomposition temperature of the electrode SND was higher than the electrode SNB. In


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comparison, SNB had lower thermostability, which might correspond to the loss of sulfur at higher temperature.32 Considering the lithium ion battery usually operates at room temperature, two organic materials are both suitable candidates for battery electrodes. The Fourier transform infrared spectroscopy (FT-IR) can provide the detailed information on the functional groups of the molecules. As illustrated in Figure 1c, the spectrum of compound SND showed typical asymmetric and symmetric stretching mode of the carbonyl (C=O) from the carboxylate (COO-) at 1556 cm-1 and 1394 cm-1, respectively. In comparison with compound SND, two sulfur atomscontaining compound SNB exhibited different characters of infrared absorptions. The carbonyl (C=O) stretching vibration of the carbothioate groups (COS-) obviously shifted to larger wavenumber of 1557 cm-1 and 1405 cm-1. And then, the characteristic peak of C-S vibration in the carbothioate groups (COS-) was aslo observed at 1004 cm-1. The as-prepared organic compounds with different morphologies were further studied by X-ray diffraction. The XRD patterns showed that SND possessed obvious characteristic diffraction peaks and weak diffraction peaks of SNB were revealed in Figure 1d. The results may be caused by the introduction of sulfur atoms. Compared to oxygen atoms, sulfur atoms have relatively large atomic radius and electron cloud density, which weakens the - stacking between molecules, leading to poor crystallinity. The different XRD patterns indicated that the crystal structure of SNB was different from SND, which was in excellent agreement with SEM results. 3.2. Electrochemical performance Two samples were tested in a coin cell with lithium metal as both counter and reference electrodes. The electrochemical Li-storage properties of organic compounds were comparatively investigated. Cyclic voltammogram (CV) were performed in the range of 0.5-3.0 V at different


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Figure 2. CV curves of (a) SND and (b) SNB at various scan rates. The discharge/charge profiles of (c) SND and (d) SNB at different current densities. (e) Rate capability at various current densities. (f) Cycle performance and coulombic efficiency.

scan rates from 0.1 to 5.0 mV s-1. Figure 2a and 2b showed CV curves of electrodes SND and SNB, respectively. The curve of SND exhibited one sharp oxidation peak at 0.96 V and one


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sharp reduction peak at 0.69 V at the slowest scanning rate. Their integral areas of redox peaks were observed to be nearly equal, reassuring the high reversibility of the reactions. In comparison, there were three pairs of reversible redox couples for SNB. Three reduction peaks at 0.77, 1.5 and 2.1 V referred to the insertion reaction of Li+ into SNB to form the compound Li3SNB. During the anodic scan, three oxidation peaks emerged at 0.96, 1.9 and 2.3 V, corresponding to the extraction reaction of Li+ from Li3SNB to form SNB. The electrochemical performance of SND and SNB were tested versus Li+/Li between 0.5 and 3.0 V at different current densities from 50 to 2000 mA g-1. Figure 2c and 2d showed the stable discharge/charge profiles of both materials in Li+ electrolyte. At a current density of 50 mA g-1, the discharge capacity of the SND electrode were 198 mAh g-1, which were lower than 280 mAh g-1 of the SNB electrode. In the discharge process, the SND revealed a flat plateau at 0.70 V vs. Li+/Li followed by a lithiation behavior. While for the charge process, the capacity-voltage profile was symmetric, indicating a reversible redox reaction. Compared to SND, SNB showed three flat plateaus at 0.98, 1.8 and 2.2 V vs. Li+/Li in the charge process, respectively. The existence of more reversible redox peaks in the capacity-voltage curves of SNB suggested that introducing electron-rich sulfur atoms could affect the operational voltage significantly. The results agreed with the CV behavior of the SNB electrode very well for the reversible reaction. Notably, the discharge/charge behavior changed from single-plateau to a slope-like behavior after sulfur incorporation. It may be due to more homogenous electron distribution induced by less electronegativity.33 To better show the advantage of introducing sulfur atoms compounds in LIBs, the rate performance of the electrodes was investigated. Figure 2e showed the rate cycling behavior of the SND and SNB electrodes at various rates. Clearly, the average discharge capacities of SNB


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(311, 245 and 207, 177, 156 and 137 mAh g-1) were higher than SND (204, 176, 159, 142, 126 and 108 mAh g-1) at various current densities of 50, 100, 200, 500, 1000 and 2000 mA g-1, respectively. Measurements were carried out and went back and forth at different rates. After 36 cycles, the current density was reduced to the starting value, the discharge capacity of SNB was still higher than SND. Compared to the SND electrode, the capacity and power density of SNB has changed significantly, due to the introducing sulfur atom structure with nanosheets affected

Figure 3. Capacitive and diffusion-controlled contributions calculated from CV scans of (a) SND and (b) SNB, respectively. (c) Comparison of capacitive and diffusion contributions of SND and SNB between 0.5 and 3.0 V at a scan rate of 1.0 mV s-1. (d) Enlarged EIS Nyquist plots derived from Figure S13. Inset showed an equivalent circuit.

the reaction interphase and Li-ions diffusion kinetics. Cycle performances and coulombic efficiency of two electrodes were revealed in Figure 2f at a current density of 200 mA g-1. As for the first discharge curves were given in Figure S12, the initial coulombic efficiencies of SND and SNB were 26 % and 27 %, respectively. These data were very close to the typical values of


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organic electrodes, which were attributed to the decomposition of electrolyte and generation of solid electrolyte interphase layer by an irreversible reaction. In other words, the low initial coulombic efficiency is due to uptake irreversible Li+ by electronic additives (carbonaceous material) and irreversibly reduce/decompose the electrolyte during the first discharge process. 3436

The reversible capacity of the SND dropped to 57 % during 100 cycles, and the SNB remained

56 % of its capacity over 100 cycles. After the second cylce, the coulombic efficiency of SNB was over 92 %, suggesting that the number of insertion/desertion Li ions in each cycle was mostly equivalent. The high reversible capacity behavior of the SNB was also exhibited in the cycle performance. The current contributions come from the capacitive and the diffusion-controlled current.37 Cyclic voltammograms of the SND and SNB electrodes were recorded at 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 mV s-1. The capacitive contribution was separated at the scan rate of 1.0 mV s-1, which were shown in Figure 3a and 3b. According to the current separation method developed by Wang and co-workers,38 35 % and 57 % of the total capacity originated from capacitive contribution (Figure 3c), indicating that capacitive-controlled process took a considerable proportion in the total electrochemical process. The results may be attributed to the nanosheets with large surface area which can effectively avoid pulverization and enable stable contact between SNB and carbon black.39 To understand the capacitive and diffusive behavior, we further investigated the electrode kinetics of SND and SNB by electrochemical impendence spectroscopy (EIS). Figure 3d showed the typical Nyquist plots and equivalent circuit for both electrodes by using a symmetric cell with two identical electrodes for a state of charge (SOC) at 0 % (half of hollow symbols).2 The compressed semicircle was related to the charge-transfer resistance (Rct) at the interface between


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the electrode and electrolyte, and the inclined line represented Warburg impedance associated with lithium ion diffusion. Apparently, SNB possessed a much lower Rct value compared with that of SND electrode (Table S1), which may be attributed to the orgainc structure contaning sulfur and its large surface effect of nanosheets. However, the relatively steeper line of SND suggested higher lithium ion diffusivity than SNB electrode. Moreover, the impedance has been measured at different potentials and at the state of charge (1.5V vs. Li+/Li) before cycling and after 5, 10 and 30 cycles. As shown in Figure S14a and S14b, the compressed semicircle of SNB was less than that of SND at same potentials, indicating the charge-transfer resistance of SNB was lower. The results obtained from EIS were in good accordance with capacitive and diffusion contributions observed from Figure 3c. The EIS curves became quasi-superposable after 10 and 30 cycles (Figure S14c and S14d), implying formation of a stable operation environment. To study the structural stabilities and structural changes of SND and SNB during the electrochemical reaction process, 1H NMR spectrum of electrode SND and SNB were measured on a Bruker Avance-400 spectrometer in D2O solvent. As shown in Figure S15a and S15b, all three characteristic peaks of the naphthalene ring were observed very clearly after discharge-charge cycles, which implied that the structure of two electrodes have not been destroyed. Compared with 1H NMR spectra of pure material (SNB), three characteristic peaks moved slightly to the low field after discharge-charge cycles, indicating the SNB underwent a different electrochemical reaction mechanism, which were further confirmed by calculation results. 3.3. Density functional theory (DFT) calculation As shown in Table S2, the average discharge potential of SNB (1.02 V) was higher than that of SND (0.81 V), and the theoretical energy density of SNB exceeded that of SND by 114 Wh g-1,


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which was due to the introduction of electron-rich sulfur atoms. Although the molecular weight of SNB was larger than that of SND, the SNB delivered a higher discharge capacity than SND. In order to show the influence of introduction of sulfur atoms, density functional theory (DFT)

Figure 4. Different electrochemical insertion/desertion pathways in (a) SND and (b) SNB were investigated by calculated LUMO orbitals with an isocontour value of 0.02.

was performed to calculate the HOMO and LUMO energy level of SND and SNB (Figure S16). The band gaps (Eg) of SND and SNB were 3.72 and 3.76 eV, indicating the almost same conductivity of two electrodes (Table S3). And then, the LUMO energy level of SND and SNB were -1.41 and -1.53 eV, respectively. As results reported in the literatures, LUMO energy level was correlated with the reduction potential of organic molecules with similar structures.40 The electron-rich sulfur atoms instead of oxygen atoms induced a decrease in energy of the LUMO orbital, in line with experimental results. To get insight into the LUMO orbital evolution, the


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changes of LUMO orbital were calculated in different electrochemical insertion/desertion pathways. When inserting Li-ions, the molecules in the electrodes were reduced, where extra electrons were pumped into LUMO, primarily. As shown in Figure 4, one SND molecule could take up two Li-ions on the dicarboxylate groups. Interestingly, the electron coupling between two sulfur atoms in different SNB molecules with larger electron density supplied an extra active site for Li-ions insertion/desertion, which responded to uptake of the three Li-ions for SNB. Compared with a large number of relevant recent publications (Table S4), the machanism of three-electron transfer was rarely reported in the symmetrical structure of organic electrode materials. Therefore, despite the similar molecular structures, the better lithiation/delithation behaviors of SNB than SND confirmed the advantages of introduction of sulfur atoms. 4. Conclusions In summary, novel sodium naphthalene-2,6-dicarboxylate (SND) and sodium naphthalene-2,6bis(carbothioate) (SNB) electrode materials have been successfully designed and synthesized. The discharge capacity of SNB was 280 mAh g-1 at a current density of 50 mA g-1, which is almost same with the theoretical capacity of the electrode calculated by three-electron transfer process (275 mAh g-1). Experiments and DFT calculations testified that SND electrode underwent a reversible two-electron reaction and the SNB electrode occurred three-electron reaction. The EIS and capacitive contribution results suggested a better rate performance and cycle stability of SNB than that of SND. The different functional groups of SND and SNB induced different electrochemical properties. The SNB electrode showed more distinctive discharge plateaus, high specific capacity and three-electron redox reaction. This work demonstrated an efficient approach to improve the specific capacity and average discharge potential of organic electrodes for lithium battery by introduction of sulfur atoms.


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ASSOCIATED CONTENT Supporting Information The supporting information is available free of charge via the Internet at http://pubs.acs.org. Materials and instrumentation, experimental details, NMR spectra, UV-vis spectra, TGA curves, the initial discharge curves, EIS Nyquist plots of SND and SNB and basic information, HOMO/LUMO orbitals and electrochemical potentials, and coordinates of molecular structures. AUTHOR INFORMATION Corresponding Author *Yaping Du. E-mail: [email protected] *Gang He. E-mail: [email protected] Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by the National Key R&D Program of China (2017YFA0208000), the China National Funds for Excellent Young Scientists (21522106), the 111 Project of China (B14040), the Fundamental Research Funds for the Central Universities (01171191320022), the National Natural Science Foundation of China (21704081, 21875180), and the Cyrus Chung Ying Tang Foundation and “National Young-1000-Plan” program. REFERENCES (1) Armand, M.; Tarascon, J. M., Building Better Batteries. Nature 2008, 451, 652-657.


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(2) Sun, H.; Mei, L.; Liang, J.; Zhao, Z.; Lee, C.; Fei, H.; Ding, M.; Lau, J.; Li, M.; Wang, C.; Xu, X.; Hao, G.; Papandrea, B.; Shakir, I.; Dunn, B.; Huang, Y.; Duan, X., ThreeDimensional Holey-Graphene/Niobia Composite Architectures for Ultrahigh-Rate Energy Storage. Science 2017, 356, 599-604. (3) Dunn, B.; Kamath, H.; Tarascon, J. M., Electrical Energy Storage for the Grid: A Battery of Choices. Science 2011, 334, 928-935. (4) Cheng, F.; Liang, J.; Tao, Z.; Chen, J., Functional Materials for Rechargeable Batteries. Adv. Mater. 2011, 23, 1695-1715. (5) Wang, Z. L.; Xu, D.; Huang, Y.; Wu, Z.; Wang, L. M.; Zhang, X. B., Facile, Mild and Fast Thermal-Decomposition Reduction of Graphene Oxide in Air and its Application in HighPerformance Lithium Batteries. Chem. Commun. 2012, 48, 976-978. (6) Simon, P.; Gogotsi, Y.; Dunn, B., Where Do Batteries End and Supercapacitors Begin? Science 2014, 343, 1210-1211. (7) Xu, J. J.; Wang, Z. L.; Xu, D.; Meng, F. Z.; Zhang, X. B., 3D Ordered Macroporous LaFeO3 as Efficient Electrocatalyst for Li-O2 Batteries with Enhanced Rate Capability and Cyclic Performance. Energy Environ. Sci. 2014, 7, 2213-2219. (8) Choi, N. S.; Chen, Z.; Freunberger, S. A.; Ji, X.; Sun, Y. K.; Amine, K.; Yushin, G.; Nazar, L. F.; Cho, J.; Bruce, P. G., Challenges Facing Lithium Batteries and Electrical DoubleLayer Capacitors. Angew. Chem. Int. Ed. 2012, 51, 9994-10024. (9) Du, Y.; Yin, Z.; Rui, X.; Zeng, Z.; Wu, X. J.; Liu, J.; Zhu, Y.; Zhu, J.; Huang, X.; Yan, Q.; Zhang, H., A Facile, Relative Green, and Inexpensive Synthetic Approach toward LargeScale Production of SnS2 Nanoplates for High-Performance Lithium-Ion Batteries. Nanoscale 2013, 5, 1456-1459. (10) Zhang, W.; Chi, Z. X.; Mao, W. X.; Lv, R. W.; Cao, A. M.; Wan, L. J., One-NanometerPrecision Control of Al2O3 Nanoshells through a Solution-Based Synthesis Route. Angew. Chem. Int. Ed. 2014, 53, 12776-12780. (11) Li, M.; Lu, J.; Chen, Z.; Amine, K., 30 Years of Lithium-Ion Batteries. Adv. Mater. 2018, 30, 1800561. (12) Zhao, Q.; Zhu, Z.; Chen, J., Molecular Engineering with Organic Carbonyl Electrode Materials for Advanced Stationary and Redox Flow Rechargeable Batteries. Adv. Mater. 2017, 29, 1607007.


18

Page 19 of 22 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


(13) Schon, T. B.; McAllister, B. T.; Li, P. F.; Seferos, D. S., The Rise of Organic Electrode Materials for Energy Storage. Chem. Soc. Rev. 2016, 45, 6345-6404. (14) Poizot, P.; Dolhem, F., Clean Energy New Deal for a Sustainable World: From Non-CO2 Generating Energy Sources to Greener Electrochemical Storage Devices. Energy Environ. Sci. 2011, 4, 2003-2019. (15) Chen, H.; Armand, M.; Demailly, G.; Dolhem, F.; Poizot, P.; Tarascon, J. M., From Biomass to a Renewable LiXC6O6 Organic Electrode for Sustainable Li-Ion Batteries. ChemSusChem 2008, 1, 348-355. (16) Song, Z.; Zhan, H.; Zhou, Y., Anthraquinone Based Polymer as High Performance Cathode Material for Rechargeable Lithium Batteries. Chem. Commun. 2009, 448-450. (17) Naoi, K.; Kawase, K. I.; Mori, M.; Komiyama, M., Electrochemistry of Poly(2,2′ ‐ dithiodianiline): A New Class of High Energy Conducting Polymer Interconnected with S-S Bonds. J. Electrochem. Soc. 1997, 144, L173-L175. (18) Liu, Z.; Kong, L.; Zhou, Y.; Zhan, C., Polyanthra [1, 9, 8-b, c, d, e][4, 10, 5-b, c, d, e] bis[1, 6, 6a (6a-S) trithia] Pentalene-Active Material for Cathode of Lithium Secondary Battery with Unusually High Specific Capacity. J. Power Sources 2006, 161, 1302-1306. (19) Janoschka, T.; Hager, M. D.; Schubert, U. S., Powering up the Future: Radical Polymers for Battery Applications. Adv. Mater. 2012, 24, 6397-6409. (20) Oyaizu, K.; Nishide, H., Radical Polymers for Organic Electronic Devices: A Radical Departure from Conjugated Polymers? Adv. Mater. 2009, 21, 2339-2344. (21) Liang, Y.; Chen, Z.; Jing, Y.; Rong, Y.; Facchetti, A.; Yao, Y., Heavily n-Dopable πConjugated Redox Polymers with Ultrafast Energy Storage Capability. J. Am. Chem. Soc. 2015, 137, 4956-4959. (22) Gracia, R.; Mecerreyes, D., Polymers with Redox Properties: Materials for Batteries, Biosensors and More. Polym. Chem. 2013, 4, 2206-2214. (23) Peng, C.; Ning, G. H.; Su, J.; Zhong, G.; Tang, W.; Tian, B.; Su, C.; Yu, D.; Zu, L.; Yang, J.; Ng, M. F.; Hu, Y. S.; Yang, Y.; Armand, M.; Loh, K. P., Reversible Multi-Electron Redox Chemistry of π-Conjugated N-containing Heteroaromatic Molecule-Based Organic Cathodes. Nat. Energy 2017, 2, 17074.


19


Page 20 of 22

(24) Petronico, A.; Bassett, K. L.; Nicolau, B. G.; Gewirth, A. A.; Nuzzo, R. G., Toward a FourElectron Redox Quinone Polymer for High Capacity Lithium Ion Storage. Adv. Energy Mater. 2017, 1700960. (25) Vadehra, G. S.; Maloney, R. P.; Garcia-Garibay, M. A.; Dunn, B., Naphthalene Diimide Based Materials with Adjustable Redox Potentials: Evaluation for Organic Lithium-Ion Batteries. Chem. Mater. 2014, 26, 7151-7157. (26) Banda, H.; Damien, D.; Nagarajan, K.; Raj, A.; Hariharan, M.; Shaijumon, M. M., Twisted Perylene Diimides with Tunable Redox Properties for Organic Sodium-Ion Batteries. Adv. Energy Mater. 2017, 7, 1701316. (27) Liang, Y.; Zhang, P.; Yang, S.; Tao, Z.; Chen, J., Fused Heteroaromatic Organic Compounds for High-Power Electrodes of Rechargeable Lithium Batteries. Adv. Energy Mater. 2013, 3, 600-605. (28) Armand, M.; Grugeon, S.; Vezin, H.; Laruelle, S.; Ribière, P.; Poizot, P.; Tarascon, J. M., Conjugated Dicarboxylate Anodes for Li-ion Batteries. Nat. Mater. 2009, 8, 120-125. (29) Yuwon, P.; Dong-Seon, S.; Hee, W. S.; Soon, C. N.; Hee, S. K.; M., O. S.; Tae, L. K.; You, H. S., Sodium Terephthalate as an Organic Anode Material for Sodium Ion Batteries. Adv. Mater. 2012, 24, 3562-3567. (30) Fédèle, L.; Sauvage, F.; Bois, J.; Tarascon, J. M.; Bécuwe, M., Lithium Insertion/DeInsertion Properties of π-Extended Naphthyl-Based Dicarboxylate Electrode Synthesized by Freeze-Drying. J. Electrochem. Soc. 2014, 161, A46-A52. (31) Zhu, G. Y.; Meng, M.; Tan, Y. N.; Xiao, X.; Liu, C. Y., Electronic Coupling between Two Covalently Bonded Dimolybdenum Units Bridged by a Naphthalene Group. Inorg. Chem. 2016, 55, 6315-6322. (32) Abreu, A. S.; Oliveira, M.; Rodrigues, P. V.; Moura, I.; Botelho, G.; Machado, A. V., Synthesis and Characterization of Polystyrene-block-poly(vinylbenzoic acid): A Promising Compound for Manipulating Photoresponsive Properties at the Nanoscale. J. Mater. Sci. 2015, 50, 2788-2796. (33) Han, X.; Qing, G.; Sun, J.; Sun, T., How Many Lithium Ions Can Be Inserted onto Fused C 6 Aromatic Ring Systems? Angew. Chem. Int. Ed. 2012, 124, 5237-5241.


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Page 21 of 22 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


(34) Wang, Y.; Deng, Y.; Qu, Q.; Zheng, X.; Zhang, J.; Liu, G.; Battaglia, V. S.; Zheng, H., Ultrahigh-Capacity Organic Anode with High-Rate Capability and Long Cycle Life for Lithium-Ion Batteries. ACS Energy Lett. 2017, 2, 2140-2148. (35) Wang, C.; Xu, Y.; Fang, Y.; Zhou, M.; Liang, L.; Singh, S.; Zhao, H.; Schober, A.; Lei, Y., Extended π-Conjugated System for Fast-Charge and -Discharge Sodium-Ion Batteries. J. Am. Chem. Soc. 2015, 137, 3124-3130. (36) Zhao, R. R.; Cao, Y. L.; Ai, X. P.; Yang, H. X., Reversible Li and Na Storage Behaviors of Perylenetetracarboxylates as Organic Anodes for Li- and Na-Ion Batteries. J. Electroanal. Chem. 2013, 688, 93-97. (37) Hu, Z.; Zhu, Z.; Cheng, F.; Zhang, K.; Wang, J.; Chen, C.; Chen, J., Pyrite FeS 2 for HighRate and Long-Life Rechargeable Sodium Batteries. Energy Environ. Sci. 2015, 8, 13091316. (38) Wang, J.; Polleux, J.; Lim, J.; Dunn, B., Pseudocapacitive Contributions to Electrochemical Energy Storage in TiO2 (Anatase) Nanoparticles. J. Phys. Chem. C 2007, 111, 1492514931. (39) Luo, C.; Huang, R.; Kevorkyants, R.; Pavanello, M.; He, H.; Wang, C., Self-Assembled Organic Nanowires for High Power Density Lithium Ion Batteries. Nano Lett. 2014, 14, 1596-1602. (40) Wang, H. G.; Yuan, S.; Si, Z.; Zhang, X. B., Multi-Ring Aromatic Carbonyl Compounds Enabling High Capacity and Stable Performance of Sodium-Organic batteries. Energy Environ. Sci. 2015, 8, 3160-3165.


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Three-Electron Redox Enabled Dithiocarboxylate Electrode for

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