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Chemical fabrication and electrochemical performance of Bi2S3-nanorods charged reduced graphene oxide
Author’s Accepted Manuscript Chemical Fabrication and electrochemical performance Of Bi2S3-nanorods Charged Reduced Graphene Oxide Ke Zhang, Yuanyuan Wang, Ping Liu, Wei Li www.elsevier.com
PII: DOI: Reference:
S0167-577X(15)30456-0 http://dx.doi.org/10.1016/j.matlet.2015.08.101 MLBLUE19462
To appear in: Materials Letters Received date: 7 July 2015 Revised date: 18 August 2015 Accepted date: 20 August 2015 Cite this article as: Ke Zhang, Yuanyuan Wang, Ping Liu and Wei Li, Chemical Fabrication and electrochemical performance Of Bi2S3-nanorods Charged Reduced Graphene Oxide, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2015.08.101 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 galley proof before it is published in its final citable 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.
Chemical Fabrication and Electrochemical Performance of Bi2S3-nanorods Charged Reduced Graphene Oxide Ke Zhang a*, Yuanyuan Wang b, Ping Liu a, Wei Li a a
School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, PR China b
Graduate School at Shenzhen, Tsinghua University, Beijing 100084, PR China
Abstract: Bi2S3-nanorods charged reduced graphene oxide (RGO) was prepared by an one-pot self-assembly method. The morphologies and structures of the samples were characterized by X-ray powder diffraction and transmission electron microscopy. The as-synthesized composite showed good crystallinity and one-dimensional nanostructures uniformly dispersed on the surface of nanorods with the diameter of 80-140 nm. Combining advantages of RGO and Bi2S3, the Bi2S3/RGO composite exhibited superior electrochemical performance to bare Bi2S3. The higher discharge/charge specific capacity, better rate capability and cycling stability were achieved for graphene-backboned hybrid architectures. Keywords: Carbon materials; Microstructure; bismuth trisulfide; anode material
1. Introduction Recently, rechargeable Li-ion batteries have been intensively investigated for its wide application in portable electronic devices, stationary energy storage systems and hybrid electric vehicles, in which anode material play a key role [1,2]. Among current anode materials, metals and metal chalcogenides of high specific capacity faced capacity fading during lithium insertion and extraction processes [3,4]. Carbon-based materials are much competitive due to its low cost, abundant sources supply and outstanding kinetics [5]. However, the energy density of graphite anode is relatively low. Thus, to decrease cyclic capacity loss by composite materials attracted more and more attention. Several contributions have devoted to the metal chalcogenides/carbon composites with good electrochemical performance for anode materials of Li-ion batteries, such as CoS/graphene [6], Bi2S3/CNT [7] and SnS2/reduced graphene oxide (RGO) [8]. Among these metal chalcogenides, Bi2S3 has been of particular interest due to its application in Li-ion batteries [9]. Jung et al. has studied the electrochemical performances of bismuth trisulfide (Bi2S3) nanoparticles and Bi2S3/C nanocomposites prepared by high-energy mechanical milling (HEMM) for Li secondary batteries [10]. Besides HEMM method, various techniques have recently been utilized to prepare Bi2S3 nanostructures, such as vapor deposition [11], hydrothermal/solvothermal synthesis [12], ultrasonic chemical method [13], electrochemical method [14] and microwave-assisted route [15]. These methods usually require relatively complicated or process expensive apparatus. In this work, we developed a facile route to prepar one-dimensional Bi2S3 nanostructures in aqueous solution at room temperature. It presents an one-pot self-assembly method to prepare Bi2S3-nanorods charged RGO. The discharge/charge electrochemical performance and cycle life performance was also investigated. *
Corresponding author. Tel./fax: +86 21 55270943.
E-mail address: [email protected] (K. Zhang). 1
2. Experimental The synthetic process of pure Bi2S3 (sample I) and Bi2S3/RGO (sample II) composite nanopowders was performed as follows: 2 mmol Bi(NO3)3·5H2O were dissolved in sequence in 50 ml 4 mol/L HNO3. A colorless and transparent solution was formed (solution A). 10 mg graphene oxide (GO) (Nanjing XF Nano Materials Tech Co., Ltd) was well disolved into 50 ml deionized water by ultrasonic dispersing and then added into solution A. 5 mmol thiacetamide were dissolved into the black mixture and then the mixture was placed without stirring. After 48h, there were black floccus precipitate on the bottom of the beaker and the solution upward became clear. The precipitate was washed with deionized water until the pH=7, and then dispersed into 50% hydrazine hydrate with stirring for 12h. The final precipitate was washed with deionized water and absolute ethanol in sequence for several times, then separated by centrifugation for 5 min at 4000 rpm and finally dried in vacuum at 70 oC. The Bi2S3 (sample III) and Bi2S3/RGO (sample IV) powders were also synthesized by using BiCl3 and hydrochloric acid instead of Bi(NO3)3·5H2O and HNO3. The phase structure of all samples was determined by X-ray diffraction (XRD) performed on a D/max-2600PC Diffractometer with CuKα radiation (λ = 1.5418Ǻ) and the morphology of samples was observed under transmission electron microscopy (TEM, Joel JEM-2100F). The electrochemical cells consisted of Bi2S3 or Bi2S3-RGO composite as the active material and 1 M solution of LiPF6 in ethylene carbonate (EC) and dimethyl carbonate (DMC, EC:DMC=1:1, v/v). The working electrode was fabricated by mixing 85:10:5 (w/w) ratio of active material, acetylene black electronic conductor and polyvynilidene fluoride binder, respectively, using N-methyl-2-pyrrolidineas the solvent and Celgard 2400 as the separator. The cells were assembled in a glove box filled with pure argon. The charge-discharge characteristics of the cells were performed over the potential range between 0.02 and 2.5 V using a NEWARE BTS 5 V-10 mA computer-controlled Galvanostat (Shenzhen, China) at room temperature.
3. Results and discussion Fig. 1 shows XRD patterns of samples I, II, III, and IV, respectively. All the diffraction peaks for sample I can be indexed to the reported Bi2S3 (JCPDS card 17-0320) with the Pbnm space group. The XRD pattern of sample II is quite similar to that of sample I. Based onexperimental details and XRD results, it can be deduced that sample I is pure Bi2S3 and sample II contains Bi2S3. The XRD patterns of samples III and IV also well matched with the JCPDS card 17-0320. However, the high background indicated poor crystallinity. Moreover, it can be seen from the curve (c) the (101) plane peak of the Bi2S3 (2θ = ~23.7o, marked by a star) is relatively stronger than the standard data. The ratio between the intensities of the (101) and (130) (the most strong) plane peaks( I(101)/I(130)) is 0.73, which is higher than standard value of 0.18, indicating that the synthesized Bi2S3 is (101)-textured. The Bi2S3 in sample IV (Fig. 1(d)) also has much higher I(101)/I(130) ratio of 0.95 than the standard data. In Fig. 2, we give a proposed formation process of the Bi2S3 nanorods modified RGO. The GO dissolved in the solution with carboxyl groupsis naturally negatively charged, which would absorb the Bi3+ ions. Meanwhile, thioacetamide was slowly hydrolyzed in the acidic solution to generate H2S. The H2S was ionized into HS- and S2- and then reacted with Bi3+ on GO to form Bi2S3 nuclei. The Bi2S3 species grow up into nanorods. As there is no surfactant added into the 2
reaction bath, the formation of one-dimensional nanostructure may attribute to the highly anisotropic structure of the orthorhombic Bi2S3. Finally, GO was reduced by hydrazine hydrate and the Bi2S3 nanorods modified RGO formed. The microstructure of as-prepared Bi2S3 and Bi2S3/graphene architectures was then investigated by TEM and selected area electron diffraction (SAED). Typical TEM images of sample I and III are shown in Fig. 3(a) and (b), respectively. It can be seen that sample I mainly consists of nanorods with the diameter of 80-140 nm. Fig. 3(b) shows that Bi2S3 prepared in HCl solution are also in one-dimensional morphology but have many spindle-like branched structures. EDS analysis indicates that the nanostuctures are composed of Bi and S (Fig. 3(c)), and the atomic ratio of Bi/S is 0.639 (very close to 2:3), which further confirms that the precipitate is Bi2S3. In Fig. 3(d), the RGO shows a crumpled silk veil-like morphology. The SAED recorded on the nanosheets shows a six-fold-symmetry diffraction pattern, which confirms that the GO has been reduced to RGO. Fig. 3(e) and (f) show that one-dimensional nanostructures with dark contrast uniformly dispersed on the surface of nanosheets with light contrast. The RGO in sample IV (Fig. 3(f)) is flexible and has wrinkled texture while that in sample II (Fig. 2(e)) is relatively thick and smooth. The electrochemical performances of Bi2S3 and Bi2S3/RGO were systematically evaluated by discharge/charge measurements at 100 mA g-1 in Fig. 4(a) and (b) for comparison. Pure Bi2S3 anode material exhibited a specific discharge/charge capacity of 921 and 598 mAh g-1, respectively. A high discharge/charge capacity of 1004 and 685 mAh g-1 is obtained at 100 mA g-1 for the Bi2S3/grapheme architecture, which is 9.0% and 14.5% higher than that of Bi2S3, respectively. As shown in Fig. 4(c), the capacity retention (11.9%, 110 mAh g-1) is much higher than that of Bi2S3 only (0.4%, 4 mAh g-1) produced by the same procedure after 50 cycles. These results clearly indicate that the graphene can not only improve the conductivity of the overall electrode, but also highly enhance the electrochemical activity of Bi2S3 during the cycle processes.
4. Conclusions Bi2S3 and Bi2S3-nanorods charged reduced graphene oxide (RGO) have been successfully prepared by an one-pot self-assembly method. The products show pure phase and uniform particle size distribution. The surface of the Bi2S3 nanorods with one-dimensional morphology prepared in HNO3 and HCl solution are both relatively smooth and rough, respectively. The electrochemical performance of Bi2S3 and Bi2S3/RGO are investigated. The results indicated that the RGO modifiaction greatly inproved the cycling stability of Bi2S3. We ascribed this to the high conductivity of RGO sheets which can subsequently enhance the speed of electron transport during an electrochemical reaction. Thus, the Bi2S3/graphene composite anode material has great potential application in Li-ion batteries.
Acknowledgements This work was supported by the National Natural Science Foundation of China under contract Nos. 51301106 and 61306018.
References [1] Goodenough J, Kim Y. Challenges for rechargeable Li batteries. Chem Mater 2010;22:587-603. 3
[2] Armand M, Tarascon JM. Building better batteries. Nature 2008;451:652-7. [3] Chen WX, Lee JY, Liu Z. The nanocomposites of carbon nanotube with Sb and SnSb0.5 as Li-ion battery anodes. Carbon 2003;41:959-66. [4] Hwang H, Kim H, Cho J. MoS2 nanoplates consisting of disordered graphene-like layers for high rate lithium battery anode materials. Nano Lett. 2011;11:4826-30. [5] Wang XS, Yang DP, Huang GS, Huang P, Shen GX, Guo SW, Mei YF, Cui DX. Rolling up graphene oxide sheets into micro/nanoscrolls by nanoparticle aggregation. J Mater Chem 2012;22:17441-4. [6] Gu Y, Xu Y, Wang Y. Graphene-wrapped CoS nanoparticles for high-capacity lithium-ion storage. ACS Appl Mater Interfaces 2013;5:801-6. [7] Zhao Y, Liu T, Xia H, Zhang L, Jiang J, Shen M, Ni J, Gao L. Branch-structured Bi2S3/CNT hybrids with improved lithium storage capability. J Mater Chem A 2014;2:13854-8. [8] Schniepp HC, Li JL, McAllister MJ, Sai H, Herrera-Alonso M, Adamson DH. Functionalized single graphene sheets derived from splitting graphite oxide. J Phys Chem B 2006;110:8535-9. [9] Jin R, Xu Y, Li G, Liu J, Chen G. Hierarchical chlorophytum-like Bi2S3 architectures with high electrochemical performance. Int J Hydrogen Energ 2013;38: 9137-44. [10] Jung H, Park CM, Sohn HJ. Bismuth sulfide and its carbon nanocomposite for rechargeable lithium-ion batteries. Electrochim Acta 2011;56:2135-9. [11] Yu XL, Cao CB. Photoresponse and field-emission properties of bismuth sulfide nanoflowers. Cryst Growth Des 2008;8:3951-5. [12] Shi HQ, Zhou XD, Fu X, Wang DB, Hu ZS. Preparation of CdS nanowires and Bi2S3 nanorods by extraction-solvothermal method. Mater Lett 2006;60:1793-5. [13] Xing GJ, Feng ZJ, Chen GH, Yao W, Song XM. Preparation of different morphologies of nanostructured bismuth sulfide with different methods. Mater Lett 2003;57:4555-9. [14] Huang XH, Yang YW, Dou XC, Zhu YG, Li GG. In situ synthesis of Bi/Bi2S3 heteronanowires with nonlinear electrical transport. J Alloys Compd 2008;461:427-31. [15] He R, Qian XF, Yin J, Zhu ZK. Preparation of Bi2S3 nanowhiskers and their morphologies. J Cryst Growth 2003;252:505-10.
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Figure captions Fig. 1. Typical XRD patterns of (a) sample I, (b) sample II, (c) sample III, and (d) sample IV, the standard pattern of Bi2S3 alloy (JCPDS card 17-0320) was given for comparison. Fig. 2. Formation process of Bi2S3/RGO composite. Fig. 3. (a) typical TEM image of sample I; (b) typical TEM image and (c) EDS spectrum of sample III; (d) typical TEM image of the pure RGO, the inset is the corresponding SAED pattern; typical TEM images of (e) sample II, and (f) sample IV. Fig. 4. Representative discharge–charge curves of Bi2S3 (a) and Bi2S3/graphene (b) architectures at different cycles between first and fifth; (c) Capacity retentions of Bi2S3 and Bi2S3/graphene architecture when performing full discharge/charge for 50 cycles at low current discharge/charge rates of 100 mA g-1.
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Figure 1
Figure 2
Figure 3
6
Figure 4
Research Highlights 7
The Bi2S3/RGO composite was prepared by a one-pot self-assembly method. The Bi2S3/RGO composite showed good crystallinity and one-dimensional nanostructure. The Bi2S3/RGO composite exhibited superior electrochemical performance to bare Bi2S3.
8
PII: DOI: Reference:
S0167-577X(15)30456-0 http://dx.doi.org/10.1016/j.matlet.2015.08.101 MLBLUE19462
To appear in: Materials Letters Received date: 7 July 2015 Revised date: 18 August 2015 Accepted date: 20 August 2015 Cite this article as: Ke Zhang, Yuanyuan Wang, Ping Liu and Wei Li, Chemical Fabrication and electrochemical performance Of Bi2S3-nanorods Charged Reduced Graphene Oxide, Materials Letters, http://dx.doi.org/10.1016/j.matlet.2015.08.101 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 galley proof before it is published in its final citable 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.
Chemical Fabrication and Electrochemical Performance of Bi2S3-nanorods Charged Reduced Graphene Oxide Ke Zhang a*, Yuanyuan Wang b, Ping Liu a, Wei Li a a
School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, PR China b
Graduate School at Shenzhen, Tsinghua University, Beijing 100084, PR China
Abstract: Bi2S3-nanorods charged reduced graphene oxide (RGO) was prepared by an one-pot self-assembly method. The morphologies and structures of the samples were characterized by X-ray powder diffraction and transmission electron microscopy. The as-synthesized composite showed good crystallinity and one-dimensional nanostructures uniformly dispersed on the surface of nanorods with the diameter of 80-140 nm. Combining advantages of RGO and Bi2S3, the Bi2S3/RGO composite exhibited superior electrochemical performance to bare Bi2S3. The higher discharge/charge specific capacity, better rate capability and cycling stability were achieved for graphene-backboned hybrid architectures. Keywords: Carbon materials; Microstructure; bismuth trisulfide; anode material
1. Introduction Recently, rechargeable Li-ion batteries have been intensively investigated for its wide application in portable electronic devices, stationary energy storage systems and hybrid electric vehicles, in which anode material play a key role [1,2]. Among current anode materials, metals and metal chalcogenides of high specific capacity faced capacity fading during lithium insertion and extraction processes [3,4]. Carbon-based materials are much competitive due to its low cost, abundant sources supply and outstanding kinetics [5]. However, the energy density of graphite anode is relatively low. Thus, to decrease cyclic capacity loss by composite materials attracted more and more attention. Several contributions have devoted to the metal chalcogenides/carbon composites with good electrochemical performance for anode materials of Li-ion batteries, such as CoS/graphene [6], Bi2S3/CNT [7] and SnS2/reduced graphene oxide (RGO) [8]. Among these metal chalcogenides, Bi2S3 has been of particular interest due to its application in Li-ion batteries [9]. Jung et al. has studied the electrochemical performances of bismuth trisulfide (Bi2S3) nanoparticles and Bi2S3/C nanocomposites prepared by high-energy mechanical milling (HEMM) for Li secondary batteries [10]. Besides HEMM method, various techniques have recently been utilized to prepare Bi2S3 nanostructures, such as vapor deposition [11], hydrothermal/solvothermal synthesis [12], ultrasonic chemical method [13], electrochemical method [14] and microwave-assisted route [15]. These methods usually require relatively complicated or process expensive apparatus. In this work, we developed a facile route to prepar one-dimensional Bi2S3 nanostructures in aqueous solution at room temperature. It presents an one-pot self-assembly method to prepare Bi2S3-nanorods charged RGO. The discharge/charge electrochemical performance and cycle life performance was also investigated. *
Corresponding author. Tel./fax: +86 21 55270943.
E-mail address: [email protected] (K. Zhang). 1
2. Experimental The synthetic process of pure Bi2S3 (sample I) and Bi2S3/RGO (sample II) composite nanopowders was performed as follows: 2 mmol Bi(NO3)3·5H2O were dissolved in sequence in 50 ml 4 mol/L HNO3. A colorless and transparent solution was formed (solution A). 10 mg graphene oxide (GO) (Nanjing XF Nano Materials Tech Co., Ltd) was well disolved into 50 ml deionized water by ultrasonic dispersing and then added into solution A. 5 mmol thiacetamide were dissolved into the black mixture and then the mixture was placed without stirring. After 48h, there were black floccus precipitate on the bottom of the beaker and the solution upward became clear. The precipitate was washed with deionized water until the pH=7, and then dispersed into 50% hydrazine hydrate with stirring for 12h. The final precipitate was washed with deionized water and absolute ethanol in sequence for several times, then separated by centrifugation for 5 min at 4000 rpm and finally dried in vacuum at 70 oC. The Bi2S3 (sample III) and Bi2S3/RGO (sample IV) powders were also synthesized by using BiCl3 and hydrochloric acid instead of Bi(NO3)3·5H2O and HNO3. The phase structure of all samples was determined by X-ray diffraction (XRD) performed on a D/max-2600PC Diffractometer with CuKα radiation (λ = 1.5418Ǻ) and the morphology of samples was observed under transmission electron microscopy (TEM, Joel JEM-2100F). The electrochemical cells consisted of Bi2S3 or Bi2S3-RGO composite as the active material and 1 M solution of LiPF6 in ethylene carbonate (EC) and dimethyl carbonate (DMC, EC:DMC=1:1, v/v). The working electrode was fabricated by mixing 85:10:5 (w/w) ratio of active material, acetylene black electronic conductor and polyvynilidene fluoride binder, respectively, using N-methyl-2-pyrrolidineas the solvent and Celgard 2400 as the separator. The cells were assembled in a glove box filled with pure argon. The charge-discharge characteristics of the cells were performed over the potential range between 0.02 and 2.5 V using a NEWARE BTS 5 V-10 mA computer-controlled Galvanostat (Shenzhen, China) at room temperature.
3. Results and discussion Fig. 1 shows XRD patterns of samples I, II, III, and IV, respectively. All the diffraction peaks for sample I can be indexed to the reported Bi2S3 (JCPDS card 17-0320) with the Pbnm space group. The XRD pattern of sample II is quite similar to that of sample I. Based onexperimental details and XRD results, it can be deduced that sample I is pure Bi2S3 and sample II contains Bi2S3. The XRD patterns of samples III and IV also well matched with the JCPDS card 17-0320. However, the high background indicated poor crystallinity. Moreover, it can be seen from the curve (c) the (101) plane peak of the Bi2S3 (2θ = ~23.7o, marked by a star) is relatively stronger than the standard data. The ratio between the intensities of the (101) and (130) (the most strong) plane peaks( I(101)/I(130)) is 0.73, which is higher than standard value of 0.18, indicating that the synthesized Bi2S3 is (101)-textured. The Bi2S3 in sample IV (Fig. 1(d)) also has much higher I(101)/I(130) ratio of 0.95 than the standard data. In Fig. 2, we give a proposed formation process of the Bi2S3 nanorods modified RGO. The GO dissolved in the solution with carboxyl groupsis naturally negatively charged, which would absorb the Bi3+ ions. Meanwhile, thioacetamide was slowly hydrolyzed in the acidic solution to generate H2S. The H2S was ionized into HS- and S2- and then reacted with Bi3+ on GO to form Bi2S3 nuclei. The Bi2S3 species grow up into nanorods. As there is no surfactant added into the 2
reaction bath, the formation of one-dimensional nanostructure may attribute to the highly anisotropic structure of the orthorhombic Bi2S3. Finally, GO was reduced by hydrazine hydrate and the Bi2S3 nanorods modified RGO formed. The microstructure of as-prepared Bi2S3 and Bi2S3/graphene architectures was then investigated by TEM and selected area electron diffraction (SAED). Typical TEM images of sample I and III are shown in Fig. 3(a) and (b), respectively. It can be seen that sample I mainly consists of nanorods with the diameter of 80-140 nm. Fig. 3(b) shows that Bi2S3 prepared in HCl solution are also in one-dimensional morphology but have many spindle-like branched structures. EDS analysis indicates that the nanostuctures are composed of Bi and S (Fig. 3(c)), and the atomic ratio of Bi/S is 0.639 (very close to 2:3), which further confirms that the precipitate is Bi2S3. In Fig. 3(d), the RGO shows a crumpled silk veil-like morphology. The SAED recorded on the nanosheets shows a six-fold-symmetry diffraction pattern, which confirms that the GO has been reduced to RGO. Fig. 3(e) and (f) show that one-dimensional nanostructures with dark contrast uniformly dispersed on the surface of nanosheets with light contrast. The RGO in sample IV (Fig. 3(f)) is flexible and has wrinkled texture while that in sample II (Fig. 2(e)) is relatively thick and smooth. The electrochemical performances of Bi2S3 and Bi2S3/RGO were systematically evaluated by discharge/charge measurements at 100 mA g-1 in Fig. 4(a) and (b) for comparison. Pure Bi2S3 anode material exhibited a specific discharge/charge capacity of 921 and 598 mAh g-1, respectively. A high discharge/charge capacity of 1004 and 685 mAh g-1 is obtained at 100 mA g-1 for the Bi2S3/grapheme architecture, which is 9.0% and 14.5% higher than that of Bi2S3, respectively. As shown in Fig. 4(c), the capacity retention (11.9%, 110 mAh g-1) is much higher than that of Bi2S3 only (0.4%, 4 mAh g-1) produced by the same procedure after 50 cycles. These results clearly indicate that the graphene can not only improve the conductivity of the overall electrode, but also highly enhance the electrochemical activity of Bi2S3 during the cycle processes.
4. Conclusions Bi2S3 and Bi2S3-nanorods charged reduced graphene oxide (RGO) have been successfully prepared by an one-pot self-assembly method. The products show pure phase and uniform particle size distribution. The surface of the Bi2S3 nanorods with one-dimensional morphology prepared in HNO3 and HCl solution are both relatively smooth and rough, respectively. The electrochemical performance of Bi2S3 and Bi2S3/RGO are investigated. The results indicated that the RGO modifiaction greatly inproved the cycling stability of Bi2S3. We ascribed this to the high conductivity of RGO sheets which can subsequently enhance the speed of electron transport during an electrochemical reaction. Thus, the Bi2S3/graphene composite anode material has great potential application in Li-ion batteries.
Acknowledgements This work was supported by the National Natural Science Foundation of China under contract Nos. 51301106 and 61306018.
References [1] Goodenough J, Kim Y. Challenges for rechargeable Li batteries. Chem Mater 2010;22:587-603. 3
[2] Armand M, Tarascon JM. Building better batteries. Nature 2008;451:652-7. [3] Chen WX, Lee JY, Liu Z. The nanocomposites of carbon nanotube with Sb and SnSb0.5 as Li-ion battery anodes. Carbon 2003;41:959-66. [4] Hwang H, Kim H, Cho J. MoS2 nanoplates consisting of disordered graphene-like layers for high rate lithium battery anode materials. Nano Lett. 2011;11:4826-30. [5] Wang XS, Yang DP, Huang GS, Huang P, Shen GX, Guo SW, Mei YF, Cui DX. Rolling up graphene oxide sheets into micro/nanoscrolls by nanoparticle aggregation. J Mater Chem 2012;22:17441-4. [6] Gu Y, Xu Y, Wang Y. Graphene-wrapped CoS nanoparticles for high-capacity lithium-ion storage. ACS Appl Mater Interfaces 2013;5:801-6. [7] Zhao Y, Liu T, Xia H, Zhang L, Jiang J, Shen M, Ni J, Gao L. Branch-structured Bi2S3/CNT hybrids with improved lithium storage capability. J Mater Chem A 2014;2:13854-8. [8] Schniepp HC, Li JL, McAllister MJ, Sai H, Herrera-Alonso M, Adamson DH. Functionalized single graphene sheets derived from splitting graphite oxide. J Phys Chem B 2006;110:8535-9. [9] Jin R, Xu Y, Li G, Liu J, Chen G. Hierarchical chlorophytum-like Bi2S3 architectures with high electrochemical performance. Int J Hydrogen Energ 2013;38: 9137-44. [10] Jung H, Park CM, Sohn HJ. Bismuth sulfide and its carbon nanocomposite for rechargeable lithium-ion batteries. Electrochim Acta 2011;56:2135-9. [11] Yu XL, Cao CB. Photoresponse and field-emission properties of bismuth sulfide nanoflowers. Cryst Growth Des 2008;8:3951-5. [12] Shi HQ, Zhou XD, Fu X, Wang DB, Hu ZS. Preparation of CdS nanowires and Bi2S3 nanorods by extraction-solvothermal method. Mater Lett 2006;60:1793-5. [13] Xing GJ, Feng ZJ, Chen GH, Yao W, Song XM. Preparation of different morphologies of nanostructured bismuth sulfide with different methods. Mater Lett 2003;57:4555-9. [14] Huang XH, Yang YW, Dou XC, Zhu YG, Li GG. In situ synthesis of Bi/Bi2S3 heteronanowires with nonlinear electrical transport. J Alloys Compd 2008;461:427-31. [15] He R, Qian XF, Yin J, Zhu ZK. Preparation of Bi2S3 nanowhiskers and their morphologies. J Cryst Growth 2003;252:505-10.
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Figure captions Fig. 1. Typical XRD patterns of (a) sample I, (b) sample II, (c) sample III, and (d) sample IV, the standard pattern of Bi2S3 alloy (JCPDS card 17-0320) was given for comparison. Fig. 2. Formation process of Bi2S3/RGO composite. Fig. 3. (a) typical TEM image of sample I; (b) typical TEM image and (c) EDS spectrum of sample III; (d) typical TEM image of the pure RGO, the inset is the corresponding SAED pattern; typical TEM images of (e) sample II, and (f) sample IV. Fig. 4. Representative discharge–charge curves of Bi2S3 (a) and Bi2S3/graphene (b) architectures at different cycles between first and fifth; (c) Capacity retentions of Bi2S3 and Bi2S3/graphene architecture when performing full discharge/charge for 50 cycles at low current discharge/charge rates of 100 mA g-1.
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Figure 1
Figure 2
Figure 3
6
Figure 4
Research Highlights 7
The Bi2S3/RGO composite was prepared by a one-pot self-assembly method. The Bi2S3/RGO composite showed good crystallinity and one-dimensional nanostructure. The Bi2S3/RGO composite exhibited superior electrochemical performance to bare Bi2S3.
8