High Energy Density Hybrid Supercapacitor: In-Situ Functionalization

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High Energy Density Hybrid Supercapacitor: In-Situ Functionalization of Vanadium-Based Colloidal Cathode Kunfeng Chen, and Dongfeng Xue ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b10638 • Publication Date (Web): 14 Oct 2016 Downloaded from http://pubs.acs.org on October 17, 2016

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ACS Applied Materials & Interfaces

High Energy Density Hybrid Supercapacitor: In-Situ Functionalization of Vanadium-Based Colloidal Cathode

Kunfeng Chen and Dongfeng Xue* State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, China *E-mail: [email protected] ABSTRACT: A novel and creative in-situ electrochemical activation method to transform vanadium ions to highly electroactive colloidal cathode in KOH solution under electric field has been designed. After undergoing electrochemical reaction, the in-situ functionalized vanadium-based colloidal cathode can adapt their geometrical structure to the high pseudocapacitive activity. The vanadium-based colloids //activated carbon asymmetric supercapcitor displays a high energy density of 50.4 Wh/kg at a power density of 250 W/kg, which is higher than the most reported vanadium-based supercapacitors. The main advantage of this system is that the materials synthesis and the device operation are performed in the same reactive environment. The obtained vanadium-based colloids can display high V3+ cation utilization ratios of about 100% for one-electron redox reactions. The present results highlight a new area of research on in-situ formation of reactive electrode materials under realistic environments, which can bring new chemistry and new structures of materials that are only present under the current in-situ reactive conditions. KEYWORDS: in-situ functionalization; VCl3; hybrid supercapacitor; electroactive colloid; high potential

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1. INTRODUCTION The increase of the energy density of supercapacitors is the most key issue for practical application. For example, electric double-layer electrode materials often show low energy density of 5-10 Wh/kg, which is 5-100 times lower than that of batteries.1,2 Pseudocapacitive electrode materials can show high energy density owing to the fast surface redox reaction, however, they often suffer from low conductivity and low specific surface area leading to reduce energy storage ability.3,4 Therefore, considerable attempts have been made to innovate the design and synthesis of transition metal oxide electrode materials from many aspects including morphologies, sizes, structures and composite.5-7 RuO2 shows metallic conductivity (σ ≈ 104 Ω−1 cm−1), while the conductivities of MnO2 and V2O5 are 10−6−10−5 and 10−5−10−3 Ω−1 cm−1. 8 Among transition metal oxides, mixed-valence vanadium oxides are promising electrode materials for pseudocapacitors, as they have multiple oxidation states (V2+, V3+, V4+, V5+) available for charge storage in a wide range of potential windows.9,10 More importantly, the conductivity of V2O3 are 103 Ω−1 cm−1 showing metallic conductivity. Therefore, we selected vanadium-based materials to construct high energy density supercapacitors. The fine control of the nature of electrode materials has spectacularly advanced due to the development of new material synthesis methods. However, most materials synthesis and devices operation typically occurred under different reactive conditions.11 In reactive and corrosive environments, most materials are likely to restructure, adapting their geometrical and electronic structure to the environments.12,13 Such processes may transform materials to new and highly reactive structures, shapes and configuration to improve their activities. After electrochemical reaction, conversion anode materials for lithium ion batteries can be transformed into polycrystalline structures, consisting of aggregated nanoparticles.14,15 These processes proved that electroactive structures can only form under realistic operating conditions. However, the traditional materials synthesis and application were generally 2 ACS Paragon Plus Environment

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separated into synthesis first and application next for device fabrication. The in situ synthesis of electroactive materials in device fabrication stage can represent a new promising strategy to improve the performance of materials.16,17 Herein, we used a mild electrochemical activation method for in-situ functionalization of vanadium-based colloidal electrode materials in KOH electrolyte. The obtained vanadiumbased electrode materials display high capacitance approaching theorectical value (4185 F/g, 0.55V). The obtained vanadium-based colloids with ionic-state resulted in excellent electrochemical behavior with high V3+ cation utilization ratios of 122% for one-electron redox reactions (Table S1). The vanadium-based colloids //activated carbon (AC) asymmetric supercapcitor displays a high energy density of 50.4 Wh/kg at a power density of 250 W/kg, which is higher than most reported values (Table 1).18-23 For example, CNT/V2O5 nanocomposite//AC supercapacitor have an energy density of 40 Wh/kg at a power density of 210 W/kg.19 V2O5 nanotube//AC asymmetric supercapacitor exhibits energy density of 46.35 Wh/ kg at power density of 1.8 kW/kg. 21 Graphene/V2O5 nanorod//AC exhibits energy density of 50 Wh/ kg at power density of 136 W/kg.22 V2O5/polyindole//AC exhibits energy density of 38.7 Wh/ kg at power density of 900 W/kg. 23 device. The MnO2 /graphene// V6O13−x@C device delivered an excellent gravimetric energy density of 45 W h/kg with an average power density of 478.5 W/kg.10 In-situ functionalized vanadium-based colloid is promising electrode materials for high energy supercapacitors.

2. EXPERIMENTAL SECTION Materials synthesis and electrochemical test Cathode materials were fabricated by in-situ synthesis process. Typically, commercial VCl3 salts were mixed with carbon black and poly(vinylidene fluoride) (PVDF) (70:20:10) to form slurry. Then the as-obtained slurry was spread onto nickel foam and dried at 70 °C for 12 h to serve as the working electrode. The in-situ electrochemical synthesis was carried out in a 3 ACS Paragon Plus Environment


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three-electrode cell with Pt wire and saturated calomel electrode (SCE) as counter and reference electrodes, while the electrolyte was 2 M KOH solution. Cyclic voltammograms (CV) was used to activate the VCl3 electrodes at the scan rate of 30 mV/s until CV curves were no longer changed (Figure S1). After 40 CV cycles in 2 M KOH solution, the in-situ electroactivated electrode was obtained, which can serve as work electrode (cathode in twoelectrode system), called activated V-based colloidal cathode. After the activation process, CV and constant-current charge-discharge tests were conducted in the same 2 M KOH electrolyte with a three-electrode cell configugation as well as Pt wire and saturated calomel electrode (SCE) as counter and reference electrodes. An electrochemical workstation CHI 660E was used to run these electrochemical tests. Hybrid supercapacitor assembly Activated carbon were mixed with carbon black and poly(vinylidene fluoride) (PVDF) (80:10:10) to form slurry. Then the as-obtained slurry was spread onto nickel foam and dried at 70 °C for 12 h to serve as anode. Supercapacitor device was assembled with cathode and anode set at two side of cellulose paper. Some drops of 2M KOH were added to cellulose paper. Then, the device was enveloped by PET. An electrochemical workstation CHI 660E was used to run electrochemical test. Calculation: The electrical charge can be calculated according to the following equation:

Q s = I∆t

(1)

where Qs is the storage charge in C, I is the current used for charge-discharge in A, ∆t is the time elapsed for the discharge cycle in s. Specific capacitance Cs values can be obtained through integration, as expressed by the following equation: Cs =

2 I ⋅ ∫ Vdt m ⋅ ∆V 2

(2)

where I represents the discharge current, dt is the discharge time, m represents the mass of V3+ or active materials, and ∆V is the discharge potential interval. 4 ACS Paragon Plus Environment

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Energy density and power density were calculated according to following equations:

0.5CV 2 E= 3600 P=

(3)

E t

(4)

where E is energy density (Wh/kg), P is energy density (W/kg), C is specific capacitance (F/g), V is voltage window (V), t is discharge (h). Herein, C was calculated based on the total mass of active cathode and anode materials. Morphological and Structural Characterization

The electrodes were characterized by a field emission scanning electron microscope (Hitachi S4800) operated at 10 kV and a transmission electron microscope (TECNAI G2,) operated at 200 kV. XRD measurements were performed on a Bruker D8 Focus diffractometer with Cu Kα radiation and a Lynx Eye detector at a scanning rate of 5 deg/min.

3. RESULTS AND DISCUSSION According to our designed strategy,17 commercial VCl3 salts were directly used to form working electrode by slurry-manufacturing method (Figure S2). After measured in KOH solution, VCl3 salts were transformed in-situ into active colloids by chemical coprecipitation reaction with KOH (Scheme 1). Figure S1 shows the CV curves of VCl3 electrode in 2M KOH electrolyte at the scan rate of 30 mV/s with initial 40 cycles. There existed weak redox peaks in the initial cycle of CV curves, and the area of the CV curves was increased with the increase of cycle number. After 40 cycles, the area of the CV curves was no longer increase, indicated the end of electrochemical activation process. The similar electrochemical activation phenomenon has been discussed by Chen et al, which suggests the occurrence of a phase conversion during the electrochemical activation process.24 X-ray diffraction (XRD) characterization was performed to study the phase conversion in electrode after 5 ACS Paragon Plus Environment


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electrochemical measurement (Figure 1). Except for the strong peaks associated with the Ni substrate, some weak peaks indexed to V2O3(OH)3 and VO2⋅H2O phases, can be found in XRD patterns. The following chemical reactions may have occurred after undergoing in-situ chemical and electrochemical reactions: 2V3+ + 8OH− → V2O3(OH)3 + H+ + 2H2O + 3e−

(5)

V3+ + 4OH− → VO2⋅H2O + H2O + e−

(6)

This XRD finding suggests that we have obtained poorly crystalline V2O3(OH)3 and VO2⋅H2O, which may lead to high electroactivity toward redox reaction. V2O3(OH)3 (Haeggite) has a monoclinic crystal structure, while the VO2⋅H2O (Lenoblite) has a orthorhombic crystal structure, which were rarely reported. However, it is reported that the intermediate metastable hydrates phases, such as V2O5⋅H2O, V3O7⋅H2O, and VO2⋅H2O, showed layer structure, which were reported to show good performance as electrodes of high-energy density batteries or supercapacitors.25,26 In this case, the metastable V2O3(OH)3 and VO2⋅H2O colloidal materials, obtained by in-situ electrocheical activation, can also display high electrochemical performance in alkaline electrolyte. SEM images show that after electrochemical measurements, spherical structures with a size of ~50 nm were formed, and they formed link-like structures (Figure 2a). Because spherical conductive carbon black was used here, we believe that the formed colloids were adsorbed at the surface of carbon black and PVDF matrix. Low-magnification TEM image shows the presence of closely contacted spherical structures with the formation of some solid matter between nanospheres (Figure 2b). Figure 2c indicates the presence of colloid particles with a diameter of ~5 nm within the carbon matrix. HRTEM images show the formation of V2O3(OH)3 phase with the lattice spacing of 0.206, 0.21, 0.247 nm, corresponding to the (311), (202), and (111) planes, respectively (Figure 2d and 2f). It should be noted that the seen nanoparticles were exposed at 200 kV high voltage, which can lead to the crystallization 6 ACS Paragon Plus Environment

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of as-obtained colloids. Selected-area electron diffraction pattern (Figure 2e) clearly shows the lattice spacings of 0.234, 0.386 nm, which correspond to (002) and (201) planes of V2O3(OH)3, respectively. This weak diffraction ring also confirms the poorly crystalline nature of the obtained colloids. The small size colloids can shorten ion diffusion and electron transfer length, leading to the improvement in electrochemical performance.27 To evaluate the application potential, we performed the cyclic voltammetry (CV) and galvanostatic charging-discharging tests to study the electrochemical performance of the activated V-based electrodes. Figure S3 show the three-cell electrochemical performances of V-based electrode after in-situ synthesis process. Figure S3a shows that the V-based electrode has a pair of oxidation and reduction peaks in CV curves, suggesting that the charge storage was mainly governed by Faradaic redox reactions.28,29 The anodic peak at 0.45 V and cathodic peak at 0.12 V at the scan rate of 5mV/s arise from the oxidation and reduction processes, respectively. Because the in-situ formed V2O3(OH)3 colloids consisted of +5 and +4 oxidation states, the following Faradaic reactions (7)-(9) could be occurring. V4+ + e− ↔ V3+

(7)

V5+ + e− ↔ V4+

(8)

V5+ + 2e− ↔ V3+

(9)

The as-obtained electrode materials have very high electroactivity and can produce oneelectron and two-electron Faradaic reactions, which can store more electric energy. At the current density of 5 A/g and the potential window of 0.55 V, the highest specific capacitance (Cs) of VCl3 salt electrode is 4185 F/g (Figure S3b). This value is higher than the theoretical Cs (3438 F/g) of one-electron redox reaction (Table S1). Therefore, two-electron Faradaic redox reaction was postulated to occur in our designed system. High V3+ cation utilization ratios of 122 % and 61 % for one-electron and two-electron reactions can be obtained. The Cs values were 4185, 3367, 2799, 2055, 1409, 318 F/g at the current densities 7 ACS Paragon Plus Environment


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of 5, 7, 10, 15, 20, 30 A/g (Figure S4). Here and elsewhere, unless otherwise noted, Cs values obtained from three-electrode cell are normalized with respect to the weight of vanadium ions. The use of Cs normalized to the weight of vanadium ion can deepen the understanding of charge storage mechanism, because Cs is associated primarily with the redox reaction of cations. By comparing the measured and theoretical Cs according to the weight of the active cations, real charge transfer reaction can be identified. The Cs values obtained according to the weight of VCl3 were 1355, 1090, 906, 665, 456, 103 F/g at the current densities of 5, 7, 10, 15, 20, 30 A/g, respectively (Figure S4). These Cs values are also higher than those previously reported for vanadium-based materials.18-23 When the as-prepared VCl3 electrode was put into the KOH electrolyte without applying electrical filed, its electrochemical activity was lower than the activated electrode. Figure S5 showed the CV and the charge/discharge curves of VCl3 electrode, which was only put into the KOH electrolyte without applying electrical filed. Specific capacitance was 456 F/g based on the weight of salts, which is smaller than that of the activated V-based electrode. To further evaluate potential for practical application, an asymmetric device was made by using the V-based electrode as the cathode and the activated carbon (AC) on Ni foam as the anode in 2 M KOH, with one piece of cellulose paper as the separator. Figure 3 show the electrochemical performance of the asymmetric device. The cell voltage was as large as 1.8 V, which was twice as high as the conventional AC based device in aqueous electrolytes (0.8–1.0 V).30,31 Unlike the three-electrode electrochemical features, the device displays a quasirectangular CV outline with feeble redox peaks. At a scan rate of 300 mV/s and a maximum cell voltage of 1.8 V, the shape of CV curve can still be well persevered, suggesting a good rate capability. Galvanostatic charge-discharge curves at various current densities are shown in Figure 3b. The nearly symmetric curves at the voltage range of 0-1.8 V confirm that the devices display ideal capacitive behavior with a rapid I-V response. The Cs values, which were calculated according to the total weight of the active materials in two electrodes, can 8 ACS Paragon Plus Environment

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reach 112 F/g at the current density of 1 A/g. The mass of V-based electrodes used in asymmetric devices was the initial mass of VCl3, which can be proper to calculate the specific capacitance and energy density of asymmetric devices. The corresponding Cs values at different current densities are also plotted as shown in Figure S6. The long-life cycle stability of the asymmetric device under the current density of 7 A/g is shown in Figure 3c. After 1000 charge/discharge cycles, the device maintained approximately 77 % of its initial capacitance. The final specific capacitance was 66 % of the initial value after 5000 charging-discharging cycles. Electrochemical impedance spectroscopy (EIS) was performed to further evaluate the electrochemical performance of the device (Figure 3d). The low values of equivalent series resistance (1.7 ohm) and charge transfer resistance (2.0 ohm) further demonstrates the exceptional electrochemical performance of the device.22,23 The curve of phase angel vs. Frequency shows the phase angel approaches 80 ° indicated the capacitor-like character, which can be confirmed by a quasi-rectangular CV curves. The energy and power densities are two important parameters that determine the electrochemical performances of this asymmetric device. Figure 4a shows the energy and power densities of the device. The asymmetric device displays a high energy density of 50.4 Wh/kg at a power density of 250 W/kg, which are higher than those of asymmetric V2O5//AC, CNT/V2O5 nanocomposite//AC, and CNT/V2O5 nanocomposite//MnO2/C devices (Table 1).21,22 Even at the high power density of 2500 W/kg, the device still has an energy density of 16.2 Wh/kg. This enhanced performance is due to in-situ formation of electroactive V-based colloids with high utilization of cations and a high cell voltage of 1.8 V. Figure 4b presents the CV curves of the optimized asymmetric device collected at different voltage windows with a scan rate of 100 mV/s. With the increase of the cell voltage to 1.8 V, the large peak current can be found. This feature can be further supported by the galvanostatic charge– discharge measurement (Figure S7). The energy density can be increased to at least by 1696 % when the cell voltage was increased from 0.8 V to 1.8 V. 9 ACS Paragon Plus Environment


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We further studied the electrochemical performance of two asymmetric supercapacitor devices connected in a series (Figures 4c,d). Two asymmetric devices can power LED indicator (3 V) for 30 min after being charged for 36 s to reach 3.6 V (inset of Figure 4c). Figure 4c shows that the asymmetric device self-discharges to approximately 1.8 V (0.5Vmax) in 8 h, a value comparable to commercial supercapacitors.30-32 Figure S8 shows that the asymmetric supercapacitor exhibits a leakage current of around 1.0 mA. Figure 4d shows Nyquist plots of two asymmetric supercapacitor devices connected in a series. The low value of equivalent series resistance (2.2 ohm) was obtained, allowing rapid electron transport, which results in the exceptional electrochemical performance of the devices. This excellent performance of our designed ionic supercapacitors may lead to promising practical applications.

4. CONCLUSIONS In summary, we proposed a new electrochemical activation route for in-situ synthesis of functionalized electrode materials in realistic environment. The commercial VCl3 salts were transformed in-situ into electroactivated V2O3(OH)3 and VO2⋅H2O colloids by chemical coprecipitation and electrochemical reaction in KOH solution. Both one-electron and twoelectron redox reactions occurred in this designed system, which can very efficiently utilize the redoxable V3+ cations in alkaline electrolyte. Therefore, the vanadium-based colloids //activated carbon asymmetric supercapcitor displays a high energy density of 50.4 Wh/kg at a power density of 250 W/kg, which is higher than most reported vanadium-based supercapacitors. A new area of research on in-situ formation of reactive materials under realistic environments is reported here which can bring new chemistry and new structures of materials that can only occur under in-situ reaction conditions.

ASSOCIATED CONTENT 10 ACS Paragon Plus Environment

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Supporting Information Schematic diagram shows the in-situ chemical coprecipitation and redox reactions of vanadium cations. Electrochemical performances of vanadium-based electrodes. This material is available free of charge via the Internet at http://pubs.acs.org.

ACKNOWLEDGEMENTS Financial support from the National Natural Science Foundation of China (Grant Nos. 51125009, 91434118), the National Natural Science Foundation for Creative Research Group (Grant No. 21521092), the External Cooperation Program of BIC, Chinese Academy of Sciences (Grant No. 121522KYS820150009), the Hundred Talents Program of the Chinese Academy of Sciences, and Jilin Provincial Science and Technology Development Program of China (Grant No. 20160520002JH) is acknowledged.

REFERENCES: (1) El-Kady, M. F.; Shao, Y.; Kaner, R. B. Graphene for Batteries, Supercapacitors and Beyond. Nat. Rev. Mater. 2016, 1, 16033. (2) Chen, K.; Song, S.; Liu, F.; Xue, D. Structural Design of Graphene for Use in Electrochemical Energy Storage Devices. Chem. Soc. Rev. 2015, 44, 6230-6257. (3) Yang, P.; Chao, D.; Zhu, C.; Xia, X.; Zhang, Y.; Wang, X.; Sun, P.; Tay, B.; Shen, Z.; Mai, W.; Fan, H. J. Ultrafast-Charging Supercapacitors Based on Corn-Like Titanium Nitride Nanostructures. Adv. Sci. 2016, 3, 1500299. (4) Chen, K.; Xue, D. Materials Chemistry toward Electrochemical Energy Storage. J. Mater. Chem. A 2016, 4, 7522-7537.

(5) Salanne, M.; Rotenberg, B.; Naoi, K.; Kaneko, K.; Taberna, P. L.; Grey, C. P.; Dunn, B.; Simon, P. Efficient Storage Mechanisms for Building Better Supercapacitors. Nat. Energy 2016, 1, 16070.



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

(6) Lin, T.; Chen, I.; Liu, F.; Yang, C.; Bi, H.; Xu, F.; Huang, F. Nitrogen-Doped Mesoporous Carbon of Extraordinary Capacitance for Electrochemical Energy Storage. Science 2015, 350, 1508-1513.

(7) Liu, F.; Song, S.; Xue, D.; Zhang, H. Folded Structured Graphene Paper for High Performance Electrode Materials. Adv. Mater. 2012, 24, 1089-1094. (8) Pan, X.; Ren, G.; Ferdous Hoque, M. N.; Bayne, S.; Zhu, K.; Fan, Z. Fast Supercapacitors Based on Graphene-Bridged V2O3/VOx Core–Shell Nanostructure Electrodes with a Power Density of 1 MW kg−1. Adv. Mater. Interfaces 2014, 1, 1400398. (9) Yu, M.; Zeng, Y.; Han, Y.; Cheng, X.; Zhao, W.; Liang, C.; Tong, Y.; Tang, H.; Lu, X. Valence-Optimized Vanadium Oxide Supercapacitor Electrodes Exhibit Ultrahigh Capacitance and Super-Long Cyclic Durability of 100 000 Cycles. Adv. Funct. Mater. 2015, 25, 3534–3540. (10) Zhai, T.; Lu, X.; Ling, Y.; Yu, M.; Wang, G.; Liu, T.; Liang, C.; Tong, Y.; Li, Y. A New Benchmark Capacitance for Supercapacitor Anodes by Mixed-Valence Sulfur-Doped V6O13− x. Adv. Mater. 2014, 26, 5869–5875. (11) Katsounaros, I.; Cherevko, S.; Zeradjanin, A. R.; Mayrhofer, K. J. J. Oxygen Electrochemistry as a Cornerstone for Sustainable Energy Conversion. Angew. Chem. Int. Ed. 2014, 53, 102-121.

(12) Tao, F.; Grass, M. E.; Zhang, Y.; Butcher, D. R.; Renzas, J. R.; Liu, Z.; Chung, J. Y.; Mun, B. S.; Salmeron, M.; Somorjai, G. A. Reaction-Driven Restructuring of Rh-Pd and Pt-Pd Core-Shell Nanoparticles. Science 2008, 322, 932-934. (13) Tao, F.; Dag, S.; Wang, L.; Liu, Z.; Butcher, D. R.; Bluhm, H.; Salmeron, M.; Somorjai, G. A. Break-Up of Stepped Platinum Catalyst Surfaces by High CO Coverage. Science 2010, 327, 850-863. (14) Wang, F.; Robert, R.; Chernova, N. A.; Pereira, N.; Omenya, F.; Badway, F.; Hua, X.; Ruotolo, M.; Zhang, R.; Wu, L.; Volkov, V.; Su, D.; Key, B.; Whittingham, M. S.; Grey, 12 ACS Paragon Plus Environment

Page 12 of 22

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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


C. P.; Amatucci, G. G.; Zhu, Y.; Graetz, J. Conversion Reaction Mechanisms in Lithium Ion Batteries: Study of the Binary Metal Fluoride Electrodes. J. Am. Chem. Soc. 2011, 133, 18828-18836.

(15) Chen, K.; Xue, D.; Komarneni, S. Beyond Theoretical Capacity in Cu-based Integrated Anode: Insight into the Structural Evolution of CuO. J. Power Sources 2015, 275, 136143. (16) Ebner, M.; Marone, F.; Stampanoni, M.; Wood, V. Visualization and Quantification of Electrochemical and Mechanical Degradation in Li Ion Batteries. Science 2013, 342, 716720. (17) Chen, K.; Xue, D.; Komarneni, S. Colloidal pseudocapacitor: Nanoscale aggregation of Mn colloids from MnCl2 under alkaline condition. J. Power Sources 2015, 279, 365-371. (18) Qu, Q. T.; Shi, Y.; Li, L. L.; Guo, W. L.; Wu, Y. P.; Zhang, H. P.; Guan, S. Y.; Holze, R. V2O5·0.6H2O Nanoribbons as Cathode Material for Asymmetric Supercapacitor in K2SO4 Solution. Electrochem. Commun. 2009, 11, 1325-1328. (19) Chen, Z.; Augustyn, V.; Wen, J.; Zhang, Y.; Shen, M.; Dunn, B.; Lu, Y. HighPerformance Supercapacitors Based on Intertwined CNT/V2O5 Nanowire Nanocomposites. Adv. Mater. 2011, 23, 791-795. (20) Chen, Z.; Qin, Y.; Weng, D.; Xiao, Q.; Peng, Y.; Wang, X.; Li, H.; Wei, F.; Lu, Y. Design and Synthesis of Hierarchical Nanowire Composites for Electrochemical Energy Storage. Adv. Funct. Mater. 2009, 19, 3420-3426. (21) Lin, Z.; Yan, X.; Lang, J.; Wang, R.; Kong, L. Adjusting Electrode Initial Potential to Obtain High-Performance Asymmetric Supercapacitor Based on Porous Vanadium Pentoxide Nanotubes and Activated Carbon Nanorods. J. Power Sources 2015, 279, 358364.



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(22) Li, G.; Wang, X.; Hassan, F. M.; Li, M.; Batmaz, R.; Xiao, X.; Yu, A. Vanadium Pentoxide Nanorods Anchored to and Wrapped with Graphene Nanosheets for HighPower Asymmetric Supercapacitors. ChemElectroChem 2015, 2, 1264-1269. (23) Zhou, X.; Chen, Q.; Wang, A.; Xu, J.; Wu, S.; Shen, J. Bamboo-like Composites of V2O5/Polyindole and Activated Carbon Cloth as Electrodes for All-Solid-State Flexible Asymmetric Supercapacitors. ACS Appl. Mater. Interfaces 2016, 8, 3776-3783. (24) Chen, H.; Kang, Y.; Cai, F.; Zeng, S.; Li, W.; Chen, M.; Li, Q. Electrochemical Conversion of Ni2(OH)2CO3 into Ni(OH)2 Hierarchical Nanostructures Loaded on a Carbon Nanotube Paper with High Electrochemical Energy Storage Performance. J. Mater. Chem. A 2015, 3, 1875–1878.

(25) Tsang, C.; Manthiram, A. Synthesis of Nanocrystalline VO2 and Its Electrochemical Behavior in Lithium Batteries. J. Electrochem. Soc. 1997, 144, 520-524. (26) Gui, Z.; Fan, R.; Chen, X. H.; Wu, Y. C. A New Metastable Phase of Needle-like Nanocrystalline VO2⋅H2O and Phase Transformation. J.Solid State Chem. 2001, 157, 250254. (27) Chen, K.; Yang, Y.; Li, K.; Ma, Z.; Zhou, Y.; Xue, D. CoCl2 Designed as Excellent Pseudocapacitor Electrode Materials. ACS Sustainable Chem. Eng. 2014, 2, 440-444. (28) Zeng, Y.; Han, Y.; Zhao, Y.; Zeng, Y.; Yu, M.; Liu, Y.; Tang, H.; Tong, Y.; Lu, X. Advanced Ti-Doped Fe2O3@PEDOT Core/Shell Anode for High-Energy Asymmetric Supercapacitors. Adv. Energy Mater. 2015, 5, 1402176. (29) Yu, M.; Cheng, X.; Zeng, Y.; Wang, Z.; Tong, Y.; Lu, X.; Yang, S. Dual-Doped Molybdenum Trioxide Nanowires: A Bifunctional Anode for Fiber-Shaped Asymmetric Supercapacitors and Microbial Fuel Cells. Angew. Chem. Int. Ed. 2016, 55, 6762 –6766. (30) EI-Kady, M. F.; Kaner, R. B. Scalable Fabrication of High-Power Graphene MicroSupercapacitors for Flexible and On-Chip Energy Storage. Nat. Commun. 2013, 4, 1475. (31) Gogotsi, Y. What Nano Can Do for Energy Storage. ACS Nano 2014, 8, 5369-5371. 14 ACS Paragon Plus Environment

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(32) Huang, M.; Li, F.; Dong, F.; Zhang, Y.; Zhang, L. MnO2-based nanostructures for highperformance supercapacitors. J. Mater. Chem. A 2015, 3, 21380-21423.



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Table 1 Comparison of electrochemical performances of vanadium oxide-based supercapacitors Energy Power Supercapacitor Voltage Electrolyte density density Ref. device (V) (Wh/kg) (W/kg) V2O5 29.0 70 1.8 V 0.5M K2SO4 16 nanoribbons//AC 20.3 2000 1 M LiClO4 in CNT/V2O5 propylene 2.7 V 40 210 17 nanocomposite//AC carbonate (PC) solution CNT/V2O5 16 75 nanocomposite// 1.6 V 1M Na2SO4 18 5.5 3750 MnO2/C V2O5 nanotube//AC

1.8 V

2 M LiNO3

46.35

1800

19

Graphene/V2O5 nanorod//AC

2.2V

1M LiClO4 in propylene carbonate

50

136.4

20

1.8 V

5 M LiNO3

38.7

900

21

1.8 V

2M KOH

50.4 16.2

250 2500

This work

V2O5/polyindole//A C V-based material//AC


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Scheme 1 Schematic diagram shows the in-situ functionalization of vanadium cations to form V-based colloidal cathode. (a) V-based electrodes were firstly fabricated, and then VCl3 was transformed into electroactive hydroxide colloids by the electric-field-assisted chemical reaction in KOH solutions. Immediately, active colloids with a large amount of electroactive cations took part in redox reaction. (b) Efficient ion diffusion and charge transfer in active hydroxide colloids. The active colloids are in pseudo-ionic state, which can show high cation utilization ratio toward Faradaic reaction.



c

Intensity (a.u.)

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

b

a

V2O3(OH)3 13-163 VO2•H2O 23-727 Ni 1-1258

10

20

30

40

50

2θ (degree)

Figure 1 XRD patterns of V-based cathode after electrochemical measurements with different aging times: (a) one day, (b) three days and (c) ten days. The standard JCPDS Nos. 13-163 for V2O3(OH)3 and 23-727 for VO2⋅H2O, and 1-1258 for Ni current collector are indicated in the graphics. After electrochemical reaction, V2O3(OH)3 and VO2⋅H2O phases formed within the electrode.


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Figure 2 SEM and TEM images of V-based cathode after electrochemical measurements. (a) SEM image, (b, c) low-magnification TEM images, (d, f) high-magnification TEM images, (e) electron diffraction pattern. Dotted circles in (c) indicate the as-formed colloid particles.



a

b 0.20

Voltage (V)

0.05

1.4

0.00 -0.05 -0.10 -0.15

1.2 1.0 1A/g 2A/g 3A/g 5A/g 7A/g 10A/g

0.8 0.6 0.4 0.2

-0.20 0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0.0

1.8

0

100

200

Voltage (V)

c

400

d

60

30

80

50

60

40 30 20

-Phase (degree)

25 20

40 20 0 -20 0.01

15

0.1

1

10 100 1000 10000100000 Frequency (Hz)

10 5

10 0

300

Time (s)

-Z'' (ohm)

Current (A)

0.10

1.8 1.6

50mV/s 100mV/s 200mV/s 300mV/s

0.15

Capacitance (F/g)

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

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0

0

1000

2000

3000

4000

5000

1

2

Cycle number

3

4

5

6

Z' (ohm)

Figure 3 Electrochemical performances of assembled V-based colloidal cathode//AC asymmetric device. (a) CV curves with scan rates between 50 and 500 mV/s, (b) galvanostatic charge-discharge curves at various current densities, (c) cycling stability of our asymmetric supercapacitor at the current density of 7A/g. (d) Nyquist plot of two asymmetric supercapacitor device, inset shows its Bode plot (phase angel vs. frequency).


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a

b 0.10

0-0.8V 0-1.0V 0-1.2V 0-1.4V 0-1.6V 0-1.8V

0.08 0.06

Current (A)

Energy density (Wh/kg)

100

V-based collods//AC

10

Graphene/V O nanorod//AC 2 5 V O /polyindole//AC 2 5 V O nanoribbons//AC 2 5

1

0.04 0.02 0.00 -0.02 -0.04

CNT/V O //AC 2 5

-0.06

CNT/V O //MnO /C 2 5 2

-0.08

100

1000

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

10000

Voltage (V)

Power density (W/kg)

d 40

3.0 2.8

-Z'' (ohm)

1.0

2.6

-Z'' (ohm)

c Open-circuit voltage (V)

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


2.4 2.2 2.0

20

0.5

0.0 2.0

2.5

3.0 Z' (ohm)

3.5

4.0

1.8 0 0

1

2

3

4

5

6

7

8

5

Time (h)

10

15

Z' (ohm)

Figure 4 Electrochemical performances of assembled V-based colloidal cathode//AC asymmetric device. (a) Ragone plots of asymmetric device. (b) CV curves with the different potential windows at the scan rate of 100mV/s. (c,d) Electrochemical performance of two asymmetric supercapacitor devices connected in a series. (c) Self-discharge curves of the two connected devices obtained immediately after precharging to 3.6 V. Inset: photograph of the supercapacitor showing two devices connected in a series, which can light up LED indicator. LED indicator in dark is also shown. (d) Nyquist plots of two asymmetric supercapacitor devices connected in a series. Inset shows an enlargement at the high frequency region.



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TOC


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High Energy Density Hybrid Supercapacitor: In-Situ Functionalization

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