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The smart fabrication of interconnected microspheres constructed by Li4Ti5O12 regular nanosheets and their lithium storage properties
Accepted Manuscript The smart fabrication of interconnected microspheres constructed by Li4Ti5O12 regular nanosheets and their lithium storage properties Qinghua Tian, Jizhang Chen, Zhengxi Zhang, Li Yang PII: DOI: Reference:
S0167-577X(17)30218-5 http://dx.doi.org/10.1016/j.matlet.2017.02.037 MLBLUE 22139
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
1 December 2016 10 January 2017 12 February 2017
Please cite this article as: Q. Tian, J. Chen, Z. Zhang, L. Yang, The smart fabrication of interconnected microspheres constructed by Li4Ti5O12 regular nanosheets and their lithium storage properties, Materials Letters (2017), doi: http://dx.doi.org/10.1016/j.matlet.2017.02.037
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.
The smart fabrication of interconnected microspheres constructed by Li4Ti5O12 regular nanosheets and their lithium storage properties Qinghua Tiana,b*, Jizhang Chenc, Zhengxi Zhangb and Li Yang b* a
Department of Chemistry, School of Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, P. R. China
b
School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
c
College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, P. R. China
*Corresponding author e-mail address: [email protected], [email protected]
Abstract: Herein, a unique hierarchical structure of interconnected microspheres constructed by regular lithium titanate (Li4Ti5O12) nanosheets has been prepared via a facile and smart approach. When evaluated as anode materials for lithium-ion batteries (LIBs), the as-prepared Li4Ti5O12 shows outstanding lithium storage performance, delivering a high reversible specific capacity of 161.9 and 141.1 mAh g-1 after 300 and 1200 cycles at 20 and 200 mA g-1, respectively. This work may open up a broader vision into developing advanced Li4Ti5O12 anode materials for LIBs. Keywords: Crystal structure; Functional; Lithium titanate; Anode; Lithium-ion batteries 1 Introduction Currently, thanks to the intrinsic characteristics of zero strain and safe operation potential, Li4 Ti5O12 (denoted as LTO) has attracted great attention as a promising anode for advanced LIBs [1-3]. Nevertheless, its wide practical use is yet hindered by two major drawbacks: one is the inherently kinetic problem, that is, low electrical conductivity and lithium-ion diffusion coefficient, eventually lead to rate capability poor [4]; the other one is the relatively low theoretical capacity of 175 mAh g-1 [3]. One of the strategies for effectively overcoming above mentioned issues is design and fabrication of nanoscale LTO materials [5]. Thus, many LTO anodes with elaborate 1 / 10
nanostructures have been prepared and exhibited improved electrochemical performance [6-8]. It is manifested that the nanostructure LTO has noted nanometer-sized effects compared with bulk LTO, such as larger specific surface area, high surface-to-volume ratio and small size. The nanometer-sized effects can bring nanostructure LTO improved electrochemical performance by increasing the contact interface between LTO and electrolyte, and reducing the transport path distance of Li-ions and electrons [9].
Fig. 1 The structure and lithium storage schematic of as-prepared LTO-NSs.
Herein, we present a smart and facile strategy for preparing LTO material with unique hierarchical structure (denoted as LTO-NSs) by one-pot hydrothermal treatment. It is worth mentioning that our strategy effectively simplifies the preparation process of nanostructure LTO compared to general methods, because it avoids the preparation of nanostructure titanium oxide precursors. The intact hierarchical structure of interconnected microspheres constructed by regular nanosheets can provide the LTO-NSs electrode with larger contact interface with electrolyte, and improved diffusion dynamic of Li-ions and electrons, as shown in Fig. 1. When tested as potential anode materials for LIBs, the LTO-NSs exhibited desirable performances. It is believed that the outstanding performance coupled with extremely facile preparation process may make LTO-NSs an attractive candidate anode material for high-power energy storage applications.
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2 Experimental section 2.1 Preparation of LTO-NSs sample Typically, 1 mL of TBT was slowly dropped into 60 mL of 0.2 M LiOH aqueous solution containing 0.05wt% of H2O2 in advance. After stirring for 30 min, the obtained yellow clear solution was transferred into a Teflon-lined stainless steel autoclave, and then placed in an oven at 180 oC for 24 h. After cooled down to room temperature naturally, the white product was collected by centrifugation, washed with anhydrous ethanol thoroughly, followed by dried in an oven at 60 o
C under vacuum overnight. Finally, the LTO-NSs was gained via the collected white precipitate
calcination at a temperature of 500 oC for 2 h in air. 2.2 Material and electrochemical characterizations The field emission scanning electron microscopy (FE-SEM, JEOL JSM-7401F) and transmission electron microscopy (TEM, JEOL JEM-2010) were applied to study the microstructures of LTO-NSs. The X-ray diffraction (XRD, Rigaku, D/max-Rb using Cu K radiation) and X-ray photoelectron spectroscopy (XPS, carried out on an AXIS ULTRA DLD instrument with using aluminum K X-ray radiation) were used to investigate the crystal structure and surface chemical state of LTO-NSs. The nitrogen (N2) adsorption/desorption isotherms (Micromeritics ASAP 2010 instrument) were adopted to measure the specific surface area of LTO-NSs. The 2016-type coin cells were used to evaluate the electrochemical performance of LTO-NSs electrodes. The working electrodes were prepared via fully mixing active material (LTO-NSs), conductive material (acetylene black, AB), and binder (sodium carboxymethyl cellulose, CMC) in a weight ratio of LTO-NSs/AB/CMC=70/20/10 in right amount of deionized water, and then 3 / 10
pasting the mixture on Cu foil to dry in a vacuum oven at 110 oC overnight. The counter electrode and separator respectively using pure lithium disc and glass fiber (GF/A). The electrolyte is composed of a solution of LiPF6 (1 M) in dimethyl carbonate (DMC) and ethylene carbonate (EC) (1:1 by volume). The CT2001a cell test instrument (LAND Electronic Co.) was used to test the galvanostatic discharge/charge cycling performance of cells with a voltage range of 1.0 to 3.0 V at room temperature. The CHI660D electrochemical workstation was applied to record Cyclic Voltammograms (CVs) of cells at a scan rate of 0.1 mV s-1 between 1.0 and 3.0 V. 3 Results and discussion The SEM images (Fig. 2a-c) clearly show that the LTO-NSs has an intact hierarchical structure of interconnected microspheres constructed by regular nanosheets instead of monodispersed hierarchical microspheres. This unique hierarchical structure can improve the diffusion dynamics of Li-ions and electrons throughout LTO-NSs electrode by decreasing the space intervals among microspheres. The average size of microspheres is estimated to be ca. 1-2 µm based on the SEM result. Apparently, it can be seen from TEM images (Fig. 2d-f) that the microspheres, assembled by regular nanosheets with thickness of about several nanometers, are closely interconnected. The inset of Fig. 2e shows the SAED patterns, five diffraction rings appear and respectively corresponding to the (111), (311), (400), (333) and (440) planes of spinel Li4Ti5O12, indicating high crystalline nature of the as-prepared LTO-NSs [10]. The inset of Fig. 2f further gives the HRTEM image of single LTO-NSs nanosheet, a set of lattice fringes with a spacing of 0.48 nm is observed and can be well assigned to the d111-spacing of spinel Li4 Ti5O12 [11].
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Fig. 2 (a-c) SEM and (d-f) TEM images of LTO-NSs; The inset of (e) and (f) showing the SAED patterns and HRTEM image, respectively.
Fig. 3 The (a) XRD patterns, (b) high resolution XPS spectra and (c) N2 adsorption and desorption isotherms of LTO-NSs.
Fig. 3a gives the XRD patterns of LTO-NSs. All of the diffraction peaks of recorded XRD patterns can be indexed into the standard peaks of spinel LTO (PDF no. 49-0207) and no impurity can be detected, indicating LTO-NSs has pure LTO phase with high crystalline [11]. Fig. 3b displays the high resolution XPS spectra of Ti 2p, the peaks can be perfectly deconvoluted into two peaks located at 464.1 and 458.3 eV, which correspond to the Ti 2p1/2 and Ti 2p3/2 core level binding energies of Ti4+ of spinel LTO, respectively [12]. Fig. 3c gives the N2 adsorption and desorption isotherms of LTO-NSs, it can be seen from that the LTO-NSs has a larger BET surface 5 / 10
area of 103.6 m2 g-1. Then, Fig. 4a gives the cycling performance of LTO-NSs at 20 mA g-1 (1 C is 175 mA g-1). It exhibits an outstanding cycling performance, delivering a capacity of 161.9 mAh g-1 after 300 cycles. And the Coulombic efficiency in this long cycle period remains almost constant at about 99.9%. Fig. 4b gives the galvanostatic discharge/charge profiles of LTO-NSs electrode at 20 mA g-1. The charge and discharge flat plateaus at around 1.62 and 1.53 V, respectively, resulting from a two-phase reaction during electrochemical lithium extraction/insertion process (Li4Ti5O12 + 3Li+ + 3e– ↔ Li7Ti5O12) [1]. Fig. 4c gives the Cyclic Voltammogram of LTO-NSs electrode. Only one pair of peaks can be observed and attributed to the redox reactions of the Ti4+/Ti3+ couple in Li4Ti5O12. Fig. 6d shows the long-term cycling performance of LTO-NSs electrode at 200 mA g-1, it delivers a specific capacity of 141.1 mAh g-1even after 1200 cycles, exhibiting excellent cycling stability. Fig. 4e displays the rate capability of LTO-NSs electrode. Specific capacity of 192.3, 174.3, 167.9, 165.9, 164.7 and 162.6 mAhg-1 is retained in fifth cycle at rate of 0.02, 0.2, 0.4, 1, 2 and 4 A g-1, respectively. Moreover, a high specific capacity of 164.4 mAh g-1 can be restored at 200th cycle when the rate backs to 0.02 A g-1, implying good rate performance and stability. The desirable performance of LTO-NSs electrode can be mainly attributed to two plausible reasons: on one hand, the unique hierarchical structure with larger specific surface will ensure a perfect contact interface between the electrode and electrolyte, which not only significantly improves the interfacial characteristic of nanostructure electrodes, but also greatly shortens the diffusion distance of Li-ions and electrons; on the other hand, the closely interconnected microspheres will able to facilitate the diffusion dynamics of Li-ions and electrons throughout electrodes via decreasing the space intervals among microspheres. 6 / 10
Fig. 4 Electrochemical characterizations of LTO-NSs electrodes: (a) Cycling performance and (b) Galvanostatic discharge/charge profiles at 20 mA g-1; (c) Cyclic voltammograms; (d) Long-term cycling performance at 200 mA g-1; (e) Rate capability.
4 Conclusions A unique hierarchical structure of Li4Ti5O12 has been successfully prepared by a facile one-pot hydrothermal approach. As potential anode for LIBs, it exhibits desirable performances, delivering a high reversible specific capacity of 161.9 mAh g-1 at 20 mA g-1 after 300 cycles, and superior rate property and even ultra-long life of 141.1 mAh g-1 at 200 mAh g-1 after 1200 cycles. It is demonstrated that the achievement of such superior electrochemical performance for Li4Ti5O12 is attributed to the synergistic effect of larger specific area and interconnected microspheres with unique hierarchical structures. This work maybe paves the way to smartly and facilely fabricate lithium-ion battery anode materials with elaborate hierarchical structures in response to the increasing demands for high-power energy storage. References [1] G.B. Xu, W. Li, L.W. Yang, X.L. Wei, J.W. Ding, J.X. Zhong, P.K. Chu, J. Power Sources 276 (2015) 247.
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[2] P.G. Bruce, B. Scrosati, J.M. Tarascon, Angew. Chem. Int. Ed. 47 (2008) 2930. [3] X.F. Wang, B. Liu, X.J. Hou, Q.F. Wang, W.W. Li, D. Chen, G.Z. Shen, Nano Res. 7 (2014) 1073. [4] L. Cheng, J. Yan, G.N. Zhu, J.Y. Luo, C.X. Wang, Y.Y. Xia, J. Mater. Chem. 20 (2010) 595. [5] Y. Wang, H. Li, R. He, E. Hosono, H. Zhou, Nanoscale 2 (2010) 1294. [6] S.J. Ding, J.S. Chen, G.G. Qi, X.N. Duan, Z.Y. Wang, E.P. Giannelis, L.A. Archer, X.W. Lou, J. Am. Chem. Soc. 133 (2011) 21. [7] Y. Shi, L. Wen, F. Li, H.M. Cheng, J. Power Sources 196 (2011) 8610. [8] D.Y. Wu, Y.X. Wang, J. Xie, G.S. Gao, T.J. Zhu, X.B. Zhao, J. Solid State Electrochem. 16 (2012) 3915. [9] H. Ge, T.T. Hao, B. Zhang, L. Chen, L.X. Cui, X.-M. Song, Electrochimica Acta 211 (2016) 119. [10] I.A. Stenina, T.L. Kulova, A.M. Skundin, A.B. Yaroslavtsev, Materials Research Bulletin 75 (2016) 178. [11] H. Ge, T.T. Hao, H. Osgood, B. Zhang, L. Chen, L.X. Cui, X.M. Song, G. Wu, ACS Appl. Mater. Interfaces 8 (2016) 9162. [12] Q. Wang, J. Geng, C. Yuan, L. Kuai, B.Y. Geng, Electrochimica Acta 212 (2016) 41.
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Graphical Abstract
The novel hierarchical structure of Li4Ti5O12 exhibits good lithium storage and ultra-long life.
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Highlights 1. The interestingly hierarchical structure of Li4Ti5O12 had been prepared. 3. It had improved diffusion dynamics of ions and electrons. 4. It had good lithium storage and ultra-long life.
10 / 10
S0167-577X(17)30218-5 http://dx.doi.org/10.1016/j.matlet.2017.02.037 MLBLUE 22139
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
1 December 2016 10 January 2017 12 February 2017
Please cite this article as: Q. Tian, J. Chen, Z. Zhang, L. Yang, The smart fabrication of interconnected microspheres constructed by Li4Ti5O12 regular nanosheets and their lithium storage properties, Materials Letters (2017), doi: http://dx.doi.org/10.1016/j.matlet.2017.02.037
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.
The smart fabrication of interconnected microspheres constructed by Li4Ti5O12 regular nanosheets and their lithium storage properties Qinghua Tiana,b*, Jizhang Chenc, Zhengxi Zhangb and Li Yang b* a
Department of Chemistry, School of Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, P. R. China
b
School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
c
College of Materials Science and Engineering, Nanjing Forestry University, Nanjing 210037, P. R. China
*Corresponding author e-mail address: [email protected], [email protected]
Abstract: Herein, a unique hierarchical structure of interconnected microspheres constructed by regular lithium titanate (Li4Ti5O12) nanosheets has been prepared via a facile and smart approach. When evaluated as anode materials for lithium-ion batteries (LIBs), the as-prepared Li4Ti5O12 shows outstanding lithium storage performance, delivering a high reversible specific capacity of 161.9 and 141.1 mAh g-1 after 300 and 1200 cycles at 20 and 200 mA g-1, respectively. This work may open up a broader vision into developing advanced Li4Ti5O12 anode materials for LIBs. Keywords: Crystal structure; Functional; Lithium titanate; Anode; Lithium-ion batteries 1 Introduction Currently, thanks to the intrinsic characteristics of zero strain and safe operation potential, Li4 Ti5O12 (denoted as LTO) has attracted great attention as a promising anode for advanced LIBs [1-3]. Nevertheless, its wide practical use is yet hindered by two major drawbacks: one is the inherently kinetic problem, that is, low electrical conductivity and lithium-ion diffusion coefficient, eventually lead to rate capability poor [4]; the other one is the relatively low theoretical capacity of 175 mAh g-1 [3]. One of the strategies for effectively overcoming above mentioned issues is design and fabrication of nanoscale LTO materials [5]. Thus, many LTO anodes with elaborate 1 / 10
nanostructures have been prepared and exhibited improved electrochemical performance [6-8]. It is manifested that the nanostructure LTO has noted nanometer-sized effects compared with bulk LTO, such as larger specific surface area, high surface-to-volume ratio and small size. The nanometer-sized effects can bring nanostructure LTO improved electrochemical performance by increasing the contact interface between LTO and electrolyte, and reducing the transport path distance of Li-ions and electrons [9].
Fig. 1 The structure and lithium storage schematic of as-prepared LTO-NSs.
Herein, we present a smart and facile strategy for preparing LTO material with unique hierarchical structure (denoted as LTO-NSs) by one-pot hydrothermal treatment. It is worth mentioning that our strategy effectively simplifies the preparation process of nanostructure LTO compared to general methods, because it avoids the preparation of nanostructure titanium oxide precursors. The intact hierarchical structure of interconnected microspheres constructed by regular nanosheets can provide the LTO-NSs electrode with larger contact interface with electrolyte, and improved diffusion dynamic of Li-ions and electrons, as shown in Fig. 1. When tested as potential anode materials for LIBs, the LTO-NSs exhibited desirable performances. It is believed that the outstanding performance coupled with extremely facile preparation process may make LTO-NSs an attractive candidate anode material for high-power energy storage applications.
2 / 10
2 Experimental section 2.1 Preparation of LTO-NSs sample Typically, 1 mL of TBT was slowly dropped into 60 mL of 0.2 M LiOH aqueous solution containing 0.05wt% of H2O2 in advance. After stirring for 30 min, the obtained yellow clear solution was transferred into a Teflon-lined stainless steel autoclave, and then placed in an oven at 180 oC for 24 h. After cooled down to room temperature naturally, the white product was collected by centrifugation, washed with anhydrous ethanol thoroughly, followed by dried in an oven at 60 o
C under vacuum overnight. Finally, the LTO-NSs was gained via the collected white precipitate
calcination at a temperature of 500 oC for 2 h in air. 2.2 Material and electrochemical characterizations The field emission scanning electron microscopy (FE-SEM, JEOL JSM-7401F) and transmission electron microscopy (TEM, JEOL JEM-2010) were applied to study the microstructures of LTO-NSs. The X-ray diffraction (XRD, Rigaku, D/max-Rb using Cu K radiation) and X-ray photoelectron spectroscopy (XPS, carried out on an AXIS ULTRA DLD instrument with using aluminum K X-ray radiation) were used to investigate the crystal structure and surface chemical state of LTO-NSs. The nitrogen (N2) adsorption/desorption isotherms (Micromeritics ASAP 2010 instrument) were adopted to measure the specific surface area of LTO-NSs. The 2016-type coin cells were used to evaluate the electrochemical performance of LTO-NSs electrodes. The working electrodes were prepared via fully mixing active material (LTO-NSs), conductive material (acetylene black, AB), and binder (sodium carboxymethyl cellulose, CMC) in a weight ratio of LTO-NSs/AB/CMC=70/20/10 in right amount of deionized water, and then 3 / 10
pasting the mixture on Cu foil to dry in a vacuum oven at 110 oC overnight. The counter electrode and separator respectively using pure lithium disc and glass fiber (GF/A). The electrolyte is composed of a solution of LiPF6 (1 M) in dimethyl carbonate (DMC) and ethylene carbonate (EC) (1:1 by volume). The CT2001a cell test instrument (LAND Electronic Co.) was used to test the galvanostatic discharge/charge cycling performance of cells with a voltage range of 1.0 to 3.0 V at room temperature. The CHI660D electrochemical workstation was applied to record Cyclic Voltammograms (CVs) of cells at a scan rate of 0.1 mV s-1 between 1.0 and 3.0 V. 3 Results and discussion The SEM images (Fig. 2a-c) clearly show that the LTO-NSs has an intact hierarchical structure of interconnected microspheres constructed by regular nanosheets instead of monodispersed hierarchical microspheres. This unique hierarchical structure can improve the diffusion dynamics of Li-ions and electrons throughout LTO-NSs electrode by decreasing the space intervals among microspheres. The average size of microspheres is estimated to be ca. 1-2 µm based on the SEM result. Apparently, it can be seen from TEM images (Fig. 2d-f) that the microspheres, assembled by regular nanosheets with thickness of about several nanometers, are closely interconnected. The inset of Fig. 2e shows the SAED patterns, five diffraction rings appear and respectively corresponding to the (111), (311), (400), (333) and (440) planes of spinel Li4Ti5O12, indicating high crystalline nature of the as-prepared LTO-NSs [10]. The inset of Fig. 2f further gives the HRTEM image of single LTO-NSs nanosheet, a set of lattice fringes with a spacing of 0.48 nm is observed and can be well assigned to the d111-spacing of spinel Li4 Ti5O12 [11].
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Fig. 2 (a-c) SEM and (d-f) TEM images of LTO-NSs; The inset of (e) and (f) showing the SAED patterns and HRTEM image, respectively.
Fig. 3 The (a) XRD patterns, (b) high resolution XPS spectra and (c) N2 adsorption and desorption isotherms of LTO-NSs.
Fig. 3a gives the XRD patterns of LTO-NSs. All of the diffraction peaks of recorded XRD patterns can be indexed into the standard peaks of spinel LTO (PDF no. 49-0207) and no impurity can be detected, indicating LTO-NSs has pure LTO phase with high crystalline [11]. Fig. 3b displays the high resolution XPS spectra of Ti 2p, the peaks can be perfectly deconvoluted into two peaks located at 464.1 and 458.3 eV, which correspond to the Ti 2p1/2 and Ti 2p3/2 core level binding energies of Ti4+ of spinel LTO, respectively [12]. Fig. 3c gives the N2 adsorption and desorption isotherms of LTO-NSs, it can be seen from that the LTO-NSs has a larger BET surface 5 / 10
area of 103.6 m2 g-1. Then, Fig. 4a gives the cycling performance of LTO-NSs at 20 mA g-1 (1 C is 175 mA g-1). It exhibits an outstanding cycling performance, delivering a capacity of 161.9 mAh g-1 after 300 cycles. And the Coulombic efficiency in this long cycle period remains almost constant at about 99.9%. Fig. 4b gives the galvanostatic discharge/charge profiles of LTO-NSs electrode at 20 mA g-1. The charge and discharge flat plateaus at around 1.62 and 1.53 V, respectively, resulting from a two-phase reaction during electrochemical lithium extraction/insertion process (Li4Ti5O12 + 3Li+ + 3e– ↔ Li7Ti5O12) [1]. Fig. 4c gives the Cyclic Voltammogram of LTO-NSs electrode. Only one pair of peaks can be observed and attributed to the redox reactions of the Ti4+/Ti3+ couple in Li4Ti5O12. Fig. 6d shows the long-term cycling performance of LTO-NSs electrode at 200 mA g-1, it delivers a specific capacity of 141.1 mAh g-1even after 1200 cycles, exhibiting excellent cycling stability. Fig. 4e displays the rate capability of LTO-NSs electrode. Specific capacity of 192.3, 174.3, 167.9, 165.9, 164.7 and 162.6 mAhg-1 is retained in fifth cycle at rate of 0.02, 0.2, 0.4, 1, 2 and 4 A g-1, respectively. Moreover, a high specific capacity of 164.4 mAh g-1 can be restored at 200th cycle when the rate backs to 0.02 A g-1, implying good rate performance and stability. The desirable performance of LTO-NSs electrode can be mainly attributed to two plausible reasons: on one hand, the unique hierarchical structure with larger specific surface will ensure a perfect contact interface between the electrode and electrolyte, which not only significantly improves the interfacial characteristic of nanostructure electrodes, but also greatly shortens the diffusion distance of Li-ions and electrons; on the other hand, the closely interconnected microspheres will able to facilitate the diffusion dynamics of Li-ions and electrons throughout electrodes via decreasing the space intervals among microspheres. 6 / 10
Fig. 4 Electrochemical characterizations of LTO-NSs electrodes: (a) Cycling performance and (b) Galvanostatic discharge/charge profiles at 20 mA g-1; (c) Cyclic voltammograms; (d) Long-term cycling performance at 200 mA g-1; (e) Rate capability.
4 Conclusions A unique hierarchical structure of Li4Ti5O12 has been successfully prepared by a facile one-pot hydrothermal approach. As potential anode for LIBs, it exhibits desirable performances, delivering a high reversible specific capacity of 161.9 mAh g-1 at 20 mA g-1 after 300 cycles, and superior rate property and even ultra-long life of 141.1 mAh g-1 at 200 mAh g-1 after 1200 cycles. It is demonstrated that the achievement of such superior electrochemical performance for Li4Ti5O12 is attributed to the synergistic effect of larger specific area and interconnected microspheres with unique hierarchical structures. This work maybe paves the way to smartly and facilely fabricate lithium-ion battery anode materials with elaborate hierarchical structures in response to the increasing demands for high-power energy storage. References [1] G.B. Xu, W. Li, L.W. Yang, X.L. Wei, J.W. Ding, J.X. Zhong, P.K. Chu, J. Power Sources 276 (2015) 247.
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[2] P.G. Bruce, B. Scrosati, J.M. Tarascon, Angew. Chem. Int. Ed. 47 (2008) 2930. [3] X.F. Wang, B. Liu, X.J. Hou, Q.F. Wang, W.W. Li, D. Chen, G.Z. Shen, Nano Res. 7 (2014) 1073. [4] L. Cheng, J. Yan, G.N. Zhu, J.Y. Luo, C.X. Wang, Y.Y. Xia, J. Mater. Chem. 20 (2010) 595. [5] Y. Wang, H. Li, R. He, E. Hosono, H. Zhou, Nanoscale 2 (2010) 1294. [6] S.J. Ding, J.S. Chen, G.G. Qi, X.N. Duan, Z.Y. Wang, E.P. Giannelis, L.A. Archer, X.W. Lou, J. Am. Chem. Soc. 133 (2011) 21. [7] Y. Shi, L. Wen, F. Li, H.M. Cheng, J. Power Sources 196 (2011) 8610. [8] D.Y. Wu, Y.X. Wang, J. Xie, G.S. Gao, T.J. Zhu, X.B. Zhao, J. Solid State Electrochem. 16 (2012) 3915. [9] H. Ge, T.T. Hao, B. Zhang, L. Chen, L.X. Cui, X.-M. Song, Electrochimica Acta 211 (2016) 119. [10] I.A. Stenina, T.L. Kulova, A.M. Skundin, A.B. Yaroslavtsev, Materials Research Bulletin 75 (2016) 178. [11] H. Ge, T.T. Hao, H. Osgood, B. Zhang, L. Chen, L.X. Cui, X.M. Song, G. Wu, ACS Appl. Mater. Interfaces 8 (2016) 9162. [12] Q. Wang, J. Geng, C. Yuan, L. Kuai, B.Y. Geng, Electrochimica Acta 212 (2016) 41.
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Graphical Abstract
The novel hierarchical structure of Li4Ti5O12 exhibits good lithium storage and ultra-long life.
9 / 10
Highlights 1. The interestingly hierarchical structure of Li4Ti5O12 had been prepared. 3. It had improved diffusion dynamics of ions and electrons. 4. It had good lithium storage and ultra-long life.
10 / 10