Effect of sulfur addition on the electrochemical performance of lithium‑vanadium-phosphate glasses as electrodes for energy storage devices

Accepted Manuscript Effect of sulfur addition on the electrochemical performance of lithium'vanadium-phosphate glasses as electrodes for energy storage devices

A.M. Al-Syadi, M.S. Al-Assiri, Hassan M.A. Hassan, Gaber El Enany, M.M. El-Desoky PII: DOI: Reference:

S1572-6657(17)30663-X doi: 10.1016/j.jelechem.2017.09.041 JEAC 3535

To appear in:

Journal of Electroanalytical Chemistry

Received date: Revised date: Accepted date:

20 July 2017 18 September 2017 19 September 2017

Please cite this article as: A.M. Al-Syadi, M.S. Al-Assiri, Hassan M.A. Hassan, Gaber El Enany, M.M. El-Desoky , Effect of sulfur addition on the electrochemical performance of lithium'vanadium-phosphate glasses as electrodes for energy storage devices, Journal of Electroanalytical Chemistry (2017), doi: 10.1016/j.jelechem.2017.09.041

This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT Effect of sulfur addition on the electrochemical performance of lithiumvanadium-phosphate glasses as electrodes for energy storage devices f

A.M. Al-Syadia,b, M.S. Al-Assiric,d, Hassan M.A. Hassane, Gaber El Enany , M.M. El-Desokya,1 (a) Physics Department, Faculty of Science, Suez University, Suez, Egypt.

T

(b) Physics Department, Faculty of Education, Ibb University, Al-Nadirah, Yemen.

IP

(c) Physics Department, College of Science and Arts, Najran University, Najran, Saudi Arabia.

CR

(d) Promising Center for Sensors and Electronic Devices (PCSED), Najran University, Saudi Arabia. (e) Chemistry Department, Faculty of Science, Suez University, Suez, Egypt.

US

(f) Scientific Department, Faculty of Engineering, Port Said University, Port Said, Egypt.

AN

Abstract

M

Glasses of the composition 37.5Li2O-25V2O5-37.5P2O5 mol% containing different sulfur (0, 10, 50, 100 mol%) content were successfully synthesized and investigated as electrodes for

ED

electrochemical devices. Both galvanostatic charge/discharge (GCD) and cyclic voltammetry

PT

(CV) were performed to study of electrochemical properties. The results showed that glasses containing sulfur (S) exhibited a high performance, such as specific capacitance, energy density

CE

and power density, compared with the S-free glass. These properties increased with increasing of

AC

S content. The outstanding electrochemical performance of the glasses containing S can be attributed to the partial substitution of oxygen (O) atoms by S atoms. Since the radius of S ion is higher than O ion, this substitution can significantly enlarge the size of Li-ion transfer pathway. Besides, S ion has better polarization ability than O ion, thus weakens the interaction between Li ions and glass network. Therefore, the addition of S into oxide glasses may be an effective way to improve the performance of electrochemical devices electrodes. 1

Corresponding author (M.M. El-Desoky):[email protected], :[email protected] 1

ACCEPTED MANUSCRIPT Keywords: sulfur addition; DSC; Lithium-vanadium-phosphate glasses; electrode materials; energy storage devices. 1. Introduction

T

Electrochemical energy storage devices have attracted great attention for their many

IP

technological applications such as portable electronics, electric vehicles (EV) and hybrid electric

CR

vehicles (HEV) [1, 2]. The rapidly evolving technology of energy storage devices requires to developing in their components, mainly the electrode materials. Consequently, the research of

US

high-performance electrode materials is important to enhance the performance of electrochemical devices. Phosphate-based lithium and multi-valence transition metal, such as

AN

vanadium, have considerable attention as electrodes for energy storage applications due to their

M

high capacity, high working voltage and good ion mobility [3˗7]. Vanadium pentoxide (V2O5)

ED

plays an important role in the field of electrochemical energy storage as appropriate host material for intercalation chemically because of the layered structures, which are well known to insert

PT

lithium ions between the layers [8-10]. In addition, the possibility of vanadium to exist in polymorphs and several oxidation states (V3+, V4+, V5+) make vanadium phosphates attractive for

CE

use in electrochemical devices, especially in Li-ion batteries [11, 12]. The reduction of V5+ to

AC

V4+ leads the samples to include both Li+ and V4+ ions. Consequently, some electrochemical activity in charge can be expected [6]. Moreover, the samples give mixed ionic/electronic conductivity occurring via transport of Li+ and electron hopping between vanadium centers [6, 13˗15]. However, doping these oxide glasses by sulfur improves the electrochemical properties because of the partial replacement of oxygen atoms by sulfur atoms. Since the radius of S ion is higher than O ion, this replacement can enlarge the size of Li-ion transport pathway. Moreover, S ion has higher polarization ability than O ion, consequently, weakens the interaction between Li2

ACCEPTED MANUSCRIPT ions and skeleton [16]. In addition, it is considered that S atoms act as a reducing agent, which causes a reduction of V ions from high valence state to low valence state [17]. This reduction is significant to obtain V3+ or V4+-containing compounds and can enhance electrochemical performance.

IP

T

In the current work, we have prepared 37.5Li2O-25V2O5-37.5P2O5 mol% containing different sulfur (0, 10, 50, 100 mol%) content and investigated the influence of sulfur addition on

CR

the electrochemical performance in these glasses as electrodes for electrochemical devices.

US

2. Experimental

AN

The glasses of the compositions 37.5Li2O-25V2O5-37.5P2O5 mol% containing different S (0, 10, 50, 100 mol%) content, which will be denoted them by (0S, 10S, 50S and 100S, respectively),

M

were synthesized using high-purity powders of lithium oxide (Li2O, 99%), vanadium oxide

ED

(V2O5, 99%), phosphorus oxide (P2O5, 99.9%) and sulfur. Suitable mixtures of these materials were heated in a covered platinum crucible at 1323 K for 20 min using an electric muffle furnace

PT

and subsequently pressed between two stainless steel plates to get glasses. The thermal

CE

measurements were determined using differential scanning calorimetry (Shimadzu DSC 50) at a heating rate of 10 K/min. X-ray diffraction (XRD Siemens D 6000) with CuKα radiation at 40

AC

kV in the 2θ range from 10 to 80º was used to check the amorphous nature of the as-synthesized samples. Scanning electron microscopy (SEM; EVO 40, ZEISS) was used to investigate the morphology of the glasses. The electrochemical measurements were performed by using threeelectrode system (VSP; Bio-Logic Science instruments) in 1 M H2SO4 as aqueous media. Our samples were acted directly as the working electrode. A platinum wire and standard calomel electrode (SCE) were used as the counter and reference electrodes, respectively. Cyclic voltammetry (CV) measurements were recorded in the potential range from ˗0.2 to 0.8 V at 3

ACCEPTED MANUSCRIPT various scan rates ranging from 10 to 200 mV s−1. Galvanostatic charge/discharge (GCD) measurements were operated from 0 to 0.8 V at a current density of 0.5, 1, 2, 2.67, 4, and 5 A g−1. The electrochemical impedance spectroscopy (EIS) was performed over a frequency range from 0.01Hz to 105 Hz at open-circuit potential 5 mV.

IP

T

3. Results and discussion

CR

3.1. X-ray diffraction (XRD)

The XRD patterns of as-synthesized glasses are shown in Fig. 1. There is a broad halo

US

observed without any sharp peaks. The overall features of these XRD patterns demonstrate the

AN

amorphous nature of as-synthesized samples.

M

3.2. Differential scanning calorimeter (DSC)

The DSC curves of S-free glass (0S) glass containing S (100S) at the heating rate of 10 K/min

ED

are displayed in Fig. 2. The behavior of these curves confirms the glassy nature in samples. The

PT

investigated glass samples exhibit endothermic peak corresponding to the glass transition temperature (Tg) followed by three exothermic peaks corresponding crystallization temperatures

CE

(Tc1, Tc2, and Tc3). The glass transition temperatures are observed at 503 and 483 K for 0S and

AC

100S samples, respectively. The crystallization temperatures for the sample 0S are observed at 589, 645 and 678 K, while they are observed at 504, 573 and 677 K for the sample 100S. Tg provides information about the strength of bonds and connectivity in the glass network. Moreover, it is known that Tg decreases with the decreasing connectivity and bond strength in the glass [18]. Furthermore, in the case of sample 0S, the three successive peaks may correspond to the precipitation of V2O5 at (Tc1) [19], LiPO3 at (Tc2) [20] and Li3V2(PO4)3 at (Tc3) [15], respectively. However, in the case of sample 100S, the three successive peaks may correspond to 4

ACCEPTED MANUSCRIPT the precipitation of Li7PS6 at (Tc1) [21], V2O5 at (Tc2) [19] and Li3V2(PO4)3 at (Tc3) [15], respectively. It can be observed that the DSC curve of sample 100S shows Li7PS6 phase instead of LiPO3 compared with the curve of sample 0S, which may be due to the partial substitution of O ions by S ions after the addition of S.

IP

T

The thermal stability factor (∆T) is usually used to evaluate the stability of glass, which is

CR

defined as [22]

(1)

US

The large difference between the first crystallization peak, Tc1, and Tg implies to the high thermal

AN

stability of the glass. The ∆T were 86 and 21 K for the samples 0S and 100S, respectively. From these results, it is clear that the Tg and ∆T of glass containing S are smaller than S-free glass,

M

indicates to the decrease of both the network connectivity and strengthening of the bonds.

ED

Because the addition of S leads to decrease bridging oxygens (BOs) due to the partial

PT

replacement of O atoms by S atoms.

3.3. Scanning electron microscopy (SEM)

CE

Fig. 3 shows the SEM images and energy dispersive X-ray (EDX) spectra of glasses 0S

AC

and 100S. This figure exhibits no detectable crystals which confirming a characteristic of the amorphous phase (as shown in Fig. 3a and b). The EDX is employed to verify the elemental composition of the sample. According to the EDX analysis (Fig. 3a′and b′), the sample 0S is composed of V, P, and O elements, while the sample 100S is composed of V, P, O and S elements. The Li element cannot be detected because of the detection limit of EDX. Therefore, the EDX analysis confirms an existence of S in the construction of the glass samples containing S. 5

ACCEPTED MANUSCRIPT 3.4. Electrochemical performance The electrochemical performance of as-synthesized glasses is investigated by cyclic voltammetry (CV), galvanostatic charged/discharge (GCD) and electrochemical impedance spectroscopy (EIS) methods at room temperature (RT). Fig. 4a-d displays the CVs of as-

T

synthesized glass electrodes in 1 M H2SO4 solution as electrolyte at various scan rates in the

IP

potential range of ˗0.2 to 0.8 V. From this figure, obviously two pairs of redox peaks appear on

CR

the CV curves of sample 0S which may be caused by Li+ intercalation/de-intercalation during the

US

charge/discharge process. The appearance of redox peaks indicates that the energy storage mechanism depends on redox reaction [23-25]. Furthermore, it can also observe that the CV

AN

curves show nearly rectangular shapes, suggesting that presence of electrochemical double layer

M

capacitance (EDLC). Thus, it can be concluded that this sample exhibits two different charge storage mechanisms, faradic capacitance and EDLC storing energy features [26˗28]. However,

ED

the CV curves of samples 10S, 50S and 100S only show nearly rectangular shapes due to the

PT

capacitive current dominates the faradaic current, which refers to the presence of EDLC [26, 29]. Fig. 4e displays the CVs of as-synthesized glass electrodes with different S content at fixed scan

CE

rate of 100 mV s−1. As observed in this figure, the current density increases with increasing of S

AC

content in samples. This result can be ascribed to decrease BOs with increasing S content, which leads to a weakening of the structure and consequently increasing of electrons/ions mobility [30]. In addition, since the radius of S ion is higher than O ion, the partial substitution of O atoms by S atoms can enlarge the size of Li-ion transport pathway [16]. Therefore, the addition of S can achieve excellent conductivity in the present glasses and consequently increasing current density. GCD behavior of as-synthesized glass electrodes in 1 M H2SO4 with the potential range from 0 to 0.8 V at different current densities of 0.5, 1, 2, 2.67, 4 and 5 A g˗1 are demonstrated in 6

ACCEPTED MANUSCRIPT Fig. 5a-d, while at fixed current density (2 A g˗1) for various S content are demonstrated in Fig. 5e. Depending on the GCD curves, the specific capacitance (CS) can be evaluated by the equation [23]:

T

(2)

IP

where Δt (in s) is the discharge time, i (in A) is the discharge current, m (in g) is the active mass

CR

of the working electrode and ΔV (in V) is the potential window. The CS dependence of current density for the present samples is displayed in Fig. 6a. It is observed that the CS values decrease

US

with increasing of current density because of insertion/de-insertion of ions at the surface of the

AN

working electrode in the electrode/electrolyte interface. When a low current is used, the specific capacitance increases due to the enough time for insertion/de-insertion of the ions at the surface

M

and subsurface of the active materials at the electrode/solution interface [31]. Fig. 6b illustrates

ED

the variation of the CS at fixed current density of 2 A g-1 as a function of S content for the present glass electrodes. From this figure, the CS increases with increase of S content. On the other hand,

PT

the CS of S-free glass (0S) decreases from 172.99 to 105 F g-1 when the current density increased

CE

from 0.5 to 5 A g-1, indicating a rate performance with 61% capacitance retention when the current density increases 10 times. The CS of glass sample 100S (which has the highest specific

AC

capacitance) decreases from 217.75 to 169.69 F g-1 when the current density increased from 0.5 to 5 A g-1, indicating a very good rate performance with 78% capacitance retention when the current density increases 10 times. It means that the sample 100S exhibits a better performance than sample 0S. This may be due to the partial replacement of O atoms by S atoms, which facilitates insertion/de-insertion of the ions on the surface and subsurface of the electrodes.

7

ACCEPTED MANUSCRIPT To evaluate further the performance of the energy storage devices, the energy density (E) (in Wh kg˗1) and power density (P) (in W kg˗1) are calculated based on the GCD curves to obtain Ragone plot (Fig. 7) by using the equations [32]

(4)

CR

IP

T

(3)

From Ragone plot, the glass 100S presents the significant improvement in both power density

US

and energy density compared with other glasses, while the glass 0S exhibits the lowest power density and energy density. The energy density of glass 100S reaches up to 19.36 Wh kg˗1 and

AN

the power density 200 W kg˗1 at the current density 0.5 A g ˗1. When the power density increases

M

to 2000 W kg˗1, the energy density remains 15.08 Wh kg˗1, indicating the remarkable rate

ED

performance of this sample has a very good electrochemical stability with about 78% retention while the power density increases 10 times. The outstanding electrochemical performance of the

PT

glasses containing S can be attributed to the partial substitution of O atoms by S atoms. Since the

CE

radius of S ion is higher than O ion, this substitution leads to enlarge the size of Li-ion diffusion pathways. Besides, the polarization capability of S ion is higher than O ion, thus weakens the

AC

interaction between Li ions and glass network. In addition, this substitution can reduce the solidity of the glass matrix due to decrease BOs: and thus, there is a weakening of the glass network, which can encourage increasing of electrons/ions mobility [16, 30]. According to the previous reasons, it can conclude that the addition of S into present glasses leads to the improvement of their rate capability and electrochemical performance.

8

ACCEPTED MANUSCRIPT The results of EIS for the present glass samples are illustrated in Fig. 8. From this figure, the Nyquist plots show slope lines in low-frequency region for all electrodes, which indicate to the capacitance nature of the storage devices. The slope line in low-frequency region is associated with Warburg impedance, which can be ascribed to the redox reaction in the

T

electrodes [33, 34]. Furthermore, the appeared slope line in the EIS plot (Fig. 8) might decide the

IP

low diffusion resistance of the present electrodes due to the wide diffusion pathways and quick

US

produce a good capacitance and electrical conductivity.

CR

ions transportation within the electrodes [33]. Therefore, these glasses may be important to

Conclusion

AN

The glasses with different S content were prepared using the press-quenching method.

M

XRD, DSC and SEM results confirm the glass nature of as-synthesized samples. The glass

ED

transition temperature (Tg) and thermal stability (ΔT) of the glasses containing S were smaller than the S-free glass due to decrease both the network connectivity and strengthening of bonds as

PT

a result of the S addition. The specific capacitance of the glass containing S electrodes was higher than the S-free glass electrode, which increased with increasing of S content. The values

CE

of specific capacitance were between (145.5 – 196.58 F g-1) at the current density of 2 A g-1. The

AC

present study suggests that fabrication of appropriate glass materials is efficient to improve the specific capacitance, charge transfer and other electrochemical properties. Therefore, these glasses may be favorable materials to use in advanced electrochemical devices with high both power and energy density. Acknowledgment

9

ACCEPTED MANUSCRIPT The authors would like to acknowledge the support of the Ministry of Higher Education, Kingdom of Saudi Arabia for supporting this research through a grant (PSCED- 003-15) under the Promising Centre for Sensors and Electronic Devices (PCSED) at Najran University,

IP

T

Kingdom of Saudi Arabia.

[1]

CR

References

J.H Lee, W.H. Shin, S.Y. Lim, B.G. Kim, J.W. Choi, Modified graphite and graphene

US

electrodes for high-performance lithium ion hybrid capacitors, Mater. Renew. Sustain.

[2]

AN

Energy 3 (2014) 22-26.

D. Puthusseri, V. Aravindan, S. Madhavi, S. Ogale, Improving the energy density of Li-ion

M

capacitors using polymer-derived porous carbons as cathode, Electrochim. Acta 130 (2014)

[3]

ED

766-770.

Y.-I. Lee, J.-H. Lee, S.-H. Hong, Y. Park, Li-ion conductivity in Li2O–B2O3–V2O5 glass

Y. Sakurai, J. Yamaki, V2O5-P2O5 glasses as cathode for lithium secondary battery, J.

CE

[4]

PT

system, J. Solid State Ionics 175 (2004) 687–690.

Electrochem. Soc. 132 (1985) 512-513. K. Nagamine, T. Honma, T. Komatsu, A fast synthesis of Li3V2(PO4)3 crystals via glass-

AC

[5]

ceramic processing and their battery performance, J. Power Sources 196 (2011) 9618-9624. [6]

D. Delaizir, V. Seznec, P. Rozier, C. Surcin, P. Salles, M. Dolle, Electrochemical performances of vitreous materials in the system Li2O–V2O5–P2O5 as electrode for lithium batteries, Solid State Ionics 237 (2013) 22-27.

10

ACCEPTED MANUSCRIPT [7]

B. Li, P. Gu, Y. Feng, G. Zhang, K. Huang, H. Xue, H. Pang, Ultrathin Nickel–Cobalt Phosphate 2D Nanosheets for Electrochemical Energy Storage under Aqueous/Solid-State Electrolyte, Adv. Funct. Mater. 27 (2017) 1605784(1-11).

[8]

M.S. Al-Assiri, M.M. El-Desoky, A. Alyamani, A. Al-Hajry, A. Al-Mogeeth, A.A. Bahgat,

T

Structural and transport properties of Li-intercalated vanadium pentoxide nanocrystalline

A.M. Al-Syadi, M.S. Al-Assiri, H.M.A. Hassan, M.M. El-Desoky, Grain size effects on

CR

[9]

IP

films, Philos. Mag. 90 (2010) 3421-3439.

dynamics of Li-ions in Li3V2(PO4)3 glass-ceramic nanocomposites, Ionics 22 (2016) 2281-

US

2290.

AN

[10] Y. Yan, B. Li, W. Guo, H. Pang, H. Xue, Vanadium based materials as electrode materials for high performance supercapacitors, J. Power Sources 329 (2016) 148-169.

M

[11] C. Shen, B. Zhang, J.-c. Zheng, Y.-d. Han, J.-f. Zhang, Effect of sintering time on the

ED

synthesize of the multi-layered core–shell LiVOPO4–Li3V2(PO4)3 composite for Li-ion batteries, J. Alloy. Compd. 622 (2015) 771-776.

PT

[12] B.M. Azmi, T. Ishihara, H. Nishiguchi, Y. Takita, Cathodic performance of VOPO4 with

170.

CE

various crystal phases for Li ion rechargeable battery, Electrochim. Acta 48 (2002) 165-

AC

[13] P. Jozwiak, J.E. Garbarczyk, Mixed electronic–ionic conductivity in the glasses of the Li2O–V2O5–P2O5 system, Solid State Ionics 176 (2005) 2163-2166. [14] A.M. Al-Syadi, E.S. Yousef, M.M. El-Desoky, M.S. Al-Assiri, Impedance spectroscopy of V2O5–Bi2O3–BaTiO3 glass–ceramics, Solid State Sciences 26 (2013) 72-82.

11

ACCEPTED MANUSCRIPT [15] A.M. Al-Syadi, M.S. Al-Assiri, H.M.A. Hassan, M.M. El-Desoky, Grain size effects on the transport properties of Li3V2(PO4)3 glass–ceramic nanocomposites for lithium cathode batteries, J. Mater. Sci: Mater. Electron. 27 (2016) 4074-4083. [16] C. Cao, Z.-B. Li, X.-L. Wang, X.-B. Zhao, W.-Q. Han, Recent advances in inorganic solid

T

electrolytes for lithium batteries, Front. Energy Res. 2 (2014) 25(1-10).

IP

[17] M.Y. Hassaan, M.M. El-Desoky, S.M. Salem, S.H. Salah, Mössbauer and electrical

CR

investigation of sulfur-doped sodium borate glasses containing iron, J. Radioanal. Nucl. Chem. 249 (2001) 595-600.

US

[18] M. Abid, M. Et-labirou, M. Taibi, Structure and DC conductivity of lead sodium

AN

ultraphosphate glasses, Mater. Sci. Eng. B 97 (2003) 20-24. [19] J.E. Garbarczyk, P. Jozwiak, M. Wasiucionek, J.L. Nowinski, Nanocrystallization as a

M

method of improvement of electrical properties and thermal stability of V 2O5-rich glasses,

ED

J. Power Sources 173 (2007) 743-747.

[20] M. Rathore, A. Dalvi, Effect of conditional glass former variation on electrical transport in

PT

Li2O-P2O5 glassy and glass-ceramic ionic system, Solid State Ionics 263 (2014) 119-124.

CE

[21] M. Tatsumisago, S. Hama, A. Hayashi, H. Morimoto, T. Minami, New lithium ion conducting glass-ceramics prepared from mechanochemical Li2S-P2S5 glasses, Solid State

AC

Ionics 154-155 (2002) 635-640. [22] A.M. Al-Syadi, E.S. Yousef, M.M. El-Desoky, M.S. Al-Assiri, Kinetic characterization of barium titanate–bismuth oxide–vanadium pentoxide glasses, Solid State Sciences 32 (2014) 48-55.

12

ACCEPTED MANUSCRIPT [23] M.M. El-Desoky, A.M. Al-Syadi, M.S. Al-Assiri, H.M.A. Hassan, G. El Enany, Electrochemical performance of novel Li3V2(PO4)3 glass-ceramic nanocomposites as electrodes for energy storage devices, J. Solid State Electrochem. 20 (2016) 2663-2671. [24] H. Pang, X. Li, Q. Zhao, H. Xue, W.-Y. Lai, Z. Hu, W. Huang, One-pot synthesis of

T

heterogeneous Co3O4-nanocube/Co(OH)2-nanosheet hybrids for high-performance flexible

IP

asymmetric all-solid-state supercapacitors, Nano Energy 35 (2017) 138-145.

CR

[25] L. Mai, H. Li, Y. Zhao, L. Xu, X. Xu, Y. Luo, Z. Zhang, W. Ke, C. Niu, Q. Zhang, Fast ionic diffusion-enabled nanoflake electrode by spontaneous electrochemical pre-

US

intercalation for high-performance supercapacitor, Scientific Reports 3 (2013) 1718(1-8).

AN

[26] L. Ye, Q. Liang, Y. Lei, X. Yu, C. Han, W. Shen, Z.-H. Huang, F. Kang, Q.-H. Yang, A high performance Li-ion capacitor constructed with Li4Ti5O12/C hybrid and porous

M

graphene macroform, J. Power Sources 282 (2015) 174-178.

ED

[27] H.-C. Tao, S.-C. Zhu, X.-L. Yang, L.-L. Zhang, S.-B. Ni, Systematic investigation of reduced graphene oxide foams for high-performance supercapacitors, Electrochim. Acta

PT

190 (2016) 168-177.

CE

[28] S.A. El-Khodary, G.M. El-Enany, M. El-Okr, M. Ibrahim, Preparation and characterization of microwave reduced graphite oxide for high-performance supercapacitors, Electrochim.

AC

Acta 150 (2014) 269-278 [29] Y. Zhu, S. Murali, M.D. Stoller, K.J. Ganesh, W. Cai, P.J. Ferreira, A. Pirkle, R.M. Wallace, K.A. Cychosz, M. Thommes, D. Su, E.A. Stach, R.S. Ruoff, Carbon-based supercapacitors produced by activation of grapheme, Science 332 (2011) 1537-1541.

13

ACCEPTED MANUSCRIPT [30] M.Y. Hassaan, M.M. El-Desoky, M.G. Moustafa, Y. Iida, S. Kubuki, T. Nishida, Role of sulfur as a reducing agent for the transition metals incorporated into lithium silicate glass, Croat. Chem. Acta 88 (2015) 505-510. [31] J.S. Shayeh, A. Ehsani, M.R. Ganjali, P. Norouzi, B. Jaleh, Conductive polymer/reduced

IP

supercapacitors, Appl. Surf. Sci. 353 (2015) 594-599.

T

graphene oxide/Au nano particles as efficient composite materials in electrochemical

CR

[32] K. Lee, D. Kim, Y. Yoon, J. Yang, H.-G. Yun, I.-K. You, H. Lee, Fast diffusion supercapacitors via an ultra-high pore volume of crumpled 3D structure reduced graphene

US

oxide activation, RSC Adv. 5 (2015) 60914-60919.

AN

[33] Z.-Y. Li, P.T.M. Bui, D.-H. Kwak, M.S. Akhtar, Q.-B.Yang, Enhanced electrochemical activity of low temperature solution process synthesized Co3O4 nanoparticles for pseudo-

M

supercapacitors applications, Ceramics International 42 (2016) 1879-1885.

ED

[34] Z. Lei, L. Lu, X.S. Zhao, The electrocapacitive properties of graphene oxide reduced by

AC

CE

PT

urea, Energy Environ. Sci 5 (2012) 6391-6399.

14

ACCEPTED MANUSCRIPT Figure captions Fig.(1) XRD for the as-synthesized glasses with different S content. Fig.(2) DSC thermogram for the glass samples 0S and 100S.

T

Fig.(3) SEM images and EDX spectra for the glass sample 0S (a, a′) and the glass sample 100S

IP

(b, b′).

CR

Fig.(4) Cyclic voltammogram curves of as-synthesized glass electrodes in 1 M H2SO4

US

electrolyte.

Fig.(5) Galvanostatic charge/discharge curves of as-synthesized glass electrodes in 1 M H2SO4

AN

electrolyte.

M

Fig.(6) (a) Variation of specific capacitance against current density and (b) Effect of S content

ED

on specific capacitance at fixed current density (2 A g-1).

PT

Fig.(7) Ragone plots of as-synthesized glass energy storage devices.

AC

CE

Fig.(8) Nyquist plots of as-synthesized glass electrodes in 1 M H2SO4 electrolyte.

15

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

AC

CE

PT

Fig. 1

16

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

AC

CE

PT

Fig. 2

17

PT

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

AC

CE

Fig. 3

18

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

AC

CE

PT

Fig. 4

19

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

AC

CE

PT

Fig. 5

20

AC

CE

PT

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

Fig. 6

21

PT

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

AC

CE

Fig. 7

22

PT

ED

M

AN

US

CR

IP

T

ACCEPTED MANUSCRIPT

AC

CE

Fig. 8

23