Hollow SnNi@PEO nanospheres as anode materials for lithium ion batteries

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 2 ( 2 0 1 7 ) 1 5 2 9 0 e1 5 2 9 8

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Hollow SnNi@PEO nanospheres as anode materials for lithium ion batteries Meiqing Guo a,b,*, Xiaogang Zhang a, Zhongchao Bai c, Jiaye Ye a, Weijia Meng a, Hui Song a,b,**, Zhihua Wang a,b,*** a

College of Mechanics, Taiyuan University of Technology, Taiyuan 030024, PR China Shanxi Key Laboratory of Material Strength and Structural Impact, Taiyuan University of Technology, Taiyuan 030024, PR China c College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, PR China b

article info

abstract

Article history:

Polyethylene oxide (PEO)-coated hollow SnNi nanospheres (SnNi@PEO) and hollow SnNi

Received 15 March 2017

nanospheres were obtained by a galvanic replacement method using Ni nanospheres as

Received in revised form

the sacrificial template association with surfactant (sodium dodecyl sulfate, SDS).

17 April 2017

Compared with hollow SnNi nanospheres and solid Sn nanospheres, the obtained

Accepted 2 May 2017

SnNi@PEO were applied for the first time in lithium ion batteries (LIBs) and showed better

Available online 20 May 2017

electrochemical properties (reversible capacity of 560 mAh g
1 after 100 cycles with a coulomb efficiency above 98%). The excellent electrochemical performance of SnNi@PEO

Keywords:

can be ascribed to hollow structure and PEO coating to alleviate volume expansion. To

Hollow SnNi nanospheres

further comprehending of the mechanical stability, a diffusion-stress coupled model was

Polyethylene oxide coating

solved numerically to simulate the diffusion-induced stress evolution of the single sphere

Lithium ion battery

during the lithiation process in LIBs.

Lithium-induced stress

© 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Introduction With wide application in the many fields, such as mobile phone, EV, HEV, and energy storage, etc., the quantity demanded for higher capacity, stable cycle performance and excellent energy density, LIBs is increasing continuously [1e4]. However, commercial graphite-based materials can no longer meet the market needs in some aspect, especially energy density and capacity [5,6]. Therefore, materials with higher specific capacity e.g., germanium-based [7e9], siliconbased [10e13], and tin-based [14e17] materials, etc., have

been studied in order to substitute the graphite-based materials to fulfill the future demands. Sn-based materials have aroused great interest of researchers because of their high theoretical specific capacity (994 mAh g
1), relatively safe lithiation/delithiation potentials, no solvent co-intercalation, and more positive intercalation potential than the graphite in LIBs [18,19]. However, during lithiation process, the extreme volume expansion (300%) of Sn anode results in great mechanical stress, leading to poor cycling performance [20e22]. This seriously hinders their practical application. The solution for this problem can be classified as three strategies. The first one is synthesis of

* Corresponding author. College of Mechanics, Taiyuan University of Technology, Taiyuan 030024, PR China. Fax: þ86 0351 3176655. ** Corresponding author. College of Mechanics, Taiyuan University of Technology, Taiyuan 030024, PR China. Fax: þ86 0351 3176655. *** Corresponding author. College of Mechanics, Taiyuan University of Technology, Taiyuan 030024, PR China. Fax: þ86 0351 3176655. E-mail addresses: [email protected] (M. Guo), [email protected] (H. Song), [email protected] (Z. Wang). http://dx.doi.org/10.1016/j.ijhydene.2017.05.015 0360-3199/© 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

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Sn-based alloys because some metals could be applied as the matrix-glue maintaining the microstructural morphology of the reactant also serves as a current collector and a quick transport medium. For example, SneFe [23], SneNi [24,25], SnCu [26], SneSbeGe [27], SnSb [28], SneCo [29,30], SneSbeCu [31], and SnSb:Co [32] were synthesized to improve the electrochemical properties of Sn. The second strategy is fabrication of Sn composites, such as core-shell Sn-multi walled carbon nanotube composite [33], nano-Sn/hard carbon composite [34], Sn nanoparticles activated carbon fiber [35], Snencapsulated spherical hollow carbon [36], and SnSb alloy encapsulated carbon microsphere [37]. Design of smart structure of metallic Sn is considered as the third effective method. Among all kinds of structures, hollow structure is more attractive because it can reduce the aggregation and pulverization of active materials in the cycle process of LIBs [38e43]. Although great improvement has been gained with those means, the electrochemical performances of Sn still can not meet the requirement of commercialization. Therefore, efforts are still needed to devote to ameliorating the electrochemical properties of Sn. Herein, hollow SnNi@PEO nanospheres were synthesized by a galvanic replacement method using Ni nanospheres as the sacrificial template in presence of SDS. This kind of nanosphere combines the advantages of the three abovementioned improvement methods. The PEO coating acts the separator/electrolyte functionality and help Sn nanostructured electrodes to form stable SEI film with high surface area; the hollow structure can alleviative the volume

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expansion and lithium-induced stress during the cycle process; and the metallic Ni acts as the matrix-glue. As expected, hollow SnNi@PEO nanospheres delivered excellent electrochemical performances including high capacity and good rate properties. In addition, a finite element model was used to simulate the diffusion-induced stress evolution of the single spheres during the cycle process.

Experimental Preparation of Ni nanospheres The Ni nanospheres were prepared via oxidationereduction method, which briefly schematic diagram as shown in Scheme 1(a). Typically, 1.26 g NiCl2$6H2O was added in 60 mL absolute ethanol and adjusting the pH to 12 with 1 M NaOH solution under stirring. Then, the above solution water bath was heated to 60  C, 15 mL hydrazine hydrate (80%) was quickly added using a pipette and kept for 30 min. Finally, the black powder was obtained by centrifugation and washed several times via ethanol and deionized water.

Preparation of hollow SnNi nanospheres The hollow SnNi nanospheres were synthesized via galvanic replacement method with the as-prepared Ni nanospheres as the template, as shown in Scheme 1(b). First, 1.5 g SnSO4 was dissolved in 150 mL deionized water with magnetic

Scheme 1 e Schematic diagram of the synthesis process of samples.

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stirring under N2 atmosphere. Then, 0.25 g as-prepared Ni nanospheres were added to the solution under ultrasonic for 0.5 h at room temperature. Next, the above solution was heated to 60  C and kept for 12 h. After that, the reaction solution was ultrasonic shake for 30 min and then a magnetic field was added at the bottom of the flask. Soon, we can found that black substance sink on the bottom of the flask. Meanwhile, the upper turbid solution was removed immediately and some distilled water was added. And then hollow SnNi nanospheres were harvested by centrifugation at 15,000 r/min, rinsed repeatedly by ethanol and deionized water, and then dried at 80  C in vacuum for 4 h. For comparison with bulk counterparts, pure Sn nanoparticles were obtained via chemical-reduction in our previous literature [29].

Preparation of hollow SnNi@PEO nanospheres As displayed in Scheme 1(c), 0.1 g as-obtained hollow SnNi nanospheres was dispersed in 50 mL distill water under ultrasonic for 0.5 h, and then 0.1 g SDS was dissolved with vigorous stirring. In addition, 0.5% PEO (Mw, 100,000) solution was dropped into the prepared solution at continuous stirring (1000 r/min) and kept for 3 h. In order to compare the effects of experimental conditions, such as the mass of PEO and SDS, stirring speed and reaction time, SnNi@PEO were prepared with different conditions (see the Supplementary Materials). Samples were obtained by centrifugation at 15,000 r/min, rinsed repeatedly with absolute ethanol, distill water and dried at 80  C in vacuum for 4 h.

cell leads to a major fraction of the stresses in the electrode materials. The stress magnitude varies over several orders of magnitude and depends on a number of factors such as the particular electrode material, the electrode architecture, electrode composition, the mechanism of Li-insertion/ removal, the electrochemical cycling rate and the potential range under consideration. Furthermore, stresses are often not uniform throughout the active electrode material [44e47]. Therefore, a diffusion-elasticity coupled model is employed to simulate the diffusion-induced stress during charge process. For simplicity, we take the assumption that the model is spherically symmetric. Then it was reduced to spatially one dimensional. The governing equations for solid spherical particle are still applicable [47], with different boundary conditions for hollow special particle. For solid spheres, the stress at the r ¼ 0 was bounded, but for hollow spherical particle, the inner surface should be stress free. For both particles, the outer boundary was assumed to be stress free. We deduced the expressions of stresses and express them as a general form: 8 9 rout > Zr >  = 3 Z 1þn U < 1 1 2ð1
2nÞ r ~cðxÞx2 drþ 3 ~cðxÞx2 dx rþ in2 uðrÞ¼ 2 3 > 1
n 3 > 1þn r rout
rin :r ; rin

2 2EU 1 6 sr ¼
4 3ð1
nÞ r3 2 st ¼

EU 1 6 4 3ð1
nÞ r3

Materials characterizations The morphology and structure of as-obtained materials were characterized by scanning electron microscope (SEM, Hitachi S-800) and transmission electron microscopy (TEM, JOEL JEM100CXII). The phase of the as-prepared products was investigated via X-ray diffraction (Rigaku D/max), which scanning rate is 8 min
1 at 20 e90 using Cu Ka as radiation.

Electrochemical measurements The working electrode were fabricated using the as-obtained samples, acetylene black, polyvinylidene fluoride by weight ratio of 8:1:1 in N-methyl-2-pyrrolidone (NMP). The well mixed mixture was painted on Cu foil and dried for 24 h in vacuum at 70  C. Then, Li metal foil as counter electrode, 1 M LiPF6 in ethylene carbonate and dimethyl carbonate (1:1 by volume) as electrolyte, Celgard 2400 as separator were assembled into CR2032 coin-type cells in a glove box filled with argon. Land battery program-control test system (CT2001A, LANHE) were using to investigate the charge/discharge performance of cell in potential range of 0.001e2.0 V.

Zr rin

Zr rin

~cðxÞx2 dx


Insertion/removal of Li-ions into/from a host crystal lattice (electrode material) during electrochemical cycling of a Li-ion

3

rin 3

2

sr þ2st 2EU 6 3 ¼
sh ¼ 4 9ð1
nÞ r3out
r3in 3

Zrout

rin

~cðxÞx2 dx7 5

2r þr3in ~cðxÞx2 dx
r3 ~cðrÞþ 3 rout
r3in

Zrout rin

3 ~cðxÞx2 dx7 5 3

~cðxÞx2 dx
~cðxÞ7 5

rin

(1) In which the solutions for solid spheres can be derived by setting rin ¼ 0, whereas rin s 0 to get the solutions for hollow spherical spheres. Where, as shown in Table 1, v, E, U and ~c represent the Poisson's ratio, Young's modulus, the partial molar volume and the concentration of lithium, respectively. The diffusion equation for lithium ion was solved using a finite difference method. At each time step, the discretized algebraic equations were linearized using the frozen coefficient method. Meanwhile, the resulted tri-diagonal matrix equation was solved by calling the ‘dgtsv’ subroutine in LAPACK. To improve the precision, a predictor-corrector algorithm was implemented at every time step. After the discretized concentration values were obtained, they were substitute to Eq. (1) to yield the discretized stresses.

Table 1 e Materials properties of SnNi. Parameter

Mechanical models

r3
r3in r3out
r3in

Zrout

Young's modulus molar volume Poisson's ratio Diffusion coefficient

Symbol and dimensions

Value

E (GPa) ~c(m3/mol) v D (m2/s)

80 3.497  10
6 0.22 7.08  10
15

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Results and discussion Stress evolution Fig. 1(a and b) plots the radial stress distribution of the solid and hollow nanospheres and the corresponding evolution with lithiation time. As one can see, for a solid nanosphere, radial stress increased at the early moment of the lithium insertion process (0e2.5 min), but suddenly declined with lithiation time after about 2.5 min, which can be ascribed to the extreme expansion of volume. It was also shown that sr always presented tensile stress and up to the maximum (20.09 MPa) in the sphere center for 2.5 min lithiation (see Fig. 1(a)). As shown in Fig. 1(b), for a hollow nanosphere, radial stress always decreased with embedded lithium time, which was because that the stress can be relieved by void space. We can see that the radial stress distribution trends of hollow spheres and the solid spheres were completely different. This is because both the hollow sphere internal and external surfaces are stress free, while the internal part of solid particles was compressed. It was worth to known that the maximum radial stress of the hollow nanosphere developed near the “neutral-layer”, and its max tension stress is much less than the solid sphere, which indicated that the hollow spheres have better mechanical performance since the stress of the former was not easy to reach the strength limit to crack failure in the cycle process.

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Fig. 1(c and d) plots the hoop stress, orthogonal with the radial direction, distribution of the solid and hollow nanospheres, and the corresponding evolution of lithiation time. Negative values mean tension stress and compression stress otherwise. Obviously, the hoop stress can be divided into two parts: the stress value was positive for the internal part of spheres (r/r0:0e0.94) and the stress value was negative for the internal part of spheres (r/r0:0.94e1) (see Fig. 1(d)), which was similar with the previous reported results [44]. This attributed to that the outside of a hollow sphere began to expand due to the lithiated, while the inside kept the original state to inhibit the external expansion. Therefore, the external surface of hollow sphere will suffer to compression stress, the internal will suffer tension stress. It is worth noting that if the material itself has cracks, the sphere will be destroyed when the tension stress breaks through the critical value. It was also observed that the max hoop stress (20 MPa) of solid spheres developed in the center for lithiated to 2.5 min (Fig. 1(c)), while the max hoop stress (2 MPa) in a hollow sphere developed on the internal surface at the moment of starting to lithiated. This significant difference of max tension stress between hollow sphere and solid sphere, which indicated that the electrode of hollow active materials possesses excellent cycle performance, ascribing to that electrode structure more stable cause the stress effect of the hollow structure is smaller in the cycling process [44].

Fig. 1 e Theoretical stress development of hollow spheres and solid spheres with the same outside diameter in lithiation process. (a) Radial stress and (c) Hoop stress evolution of a solid Sn sphere at lithiation rate of 0.1 C for 0.5, 1, 2.5, 5, 10 min, and 30 min. (b) Radial stress and (d) Hoop stress evolution of a hollow Sn sphere at lithiation rate of 0.1 C for 0.5, 1, 2.5, 5, 10 min, and 15 min (r and r0 represent the distance from the center and the outer radius, respectively).

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Fig. 2 e TEM and SEM micrographs of (a and d) Ni nanospheres, (b and e) hollow SnNi nanospheres and (c and f) SnNi@PEO. Inset of (c) HRTEM of SnNi@PEO.

Morphology and structure Fig. 2(a and d) displays the TEM and SEM micrographs of Ni nanospheres, respectively. The results revealed that Ni nanospheres possess solid spherical structures with a diameter of about 105 nm, which was consistent with the results from diameter distribution measurements in Fig. 3(a). As shown in Fig. 2(b and e), the particles are slick, hollow and scattered. The mean diameter of these particles evenly was about 180 nm (show in Fig. 3(b)). As can been observed in Fig. 2(c and f), the nanoparticles were coated a uniform PEO layer with thickness of about 30 nm. The polymer layer can not only alleviate the volume expansion of the electrode in cycling process, but also can prevent the direct contact among the active material with active material or active material with electrolyte [40]. Based on these effects, the structure of the electrode can be kept stable, and the cycle life can be prolonged. As displayed in Fig. 4, all the reflection peaks of Ni nanospheres are indexed to cubic Ni (JCPDS No. 04-0850, Space group Fm3m) without any other impurities. The reflection peaks around 44.3471 , 51.6731 , and 76.0951 correspond to the (1 1 1), (2 0 0) and (2 2 0) crystal planes of cubic Ni. The diffraction peaks of hollow SnNi nanospheres appeared at

30.645 , 32.020 , 43.869 , 44.902 , 55.330 , 62.539 , 63.784 , 64.575 , 72.414 , 73.194 and 79.470 can be indexed to the standard diffraction data of (2 0 0), (1 0 1), (2 2 0), (2 1 1), (3 0 1), (1 1 2), (4 0 0), (3 2 1), (4 2 0), (4 1 1) and (3 1 2) of tetragonal Sn (JCPDS No. 04-0673, Space group 141/amd (141)). Owing to the low content, the peaks of the PEO layer are neither found in Fig. 4(c). Therefore, no difference can be observed for the reflection peaks of SnNi and SnNi@PEO nanospheres.

Electrochemical performance Fig. 5(a) demonstrates the cycling performance of Sn electrode, hollow SnNi electrode and SnNi@PEO electrode. There is a sharp capacity loss in the initial cycles of all the three samples, because the electrolyte decomposition to form the SEI layer on the surface of the electrode [45]. This is very common in LIBs. Owing to the protection of PEO layer, SnNi@PEO first reaches a stable capacity of 689 mAh g
1 and keeps this value until 100 cycles. Without the PEO, hollow SnNi nanospheres show a lower capacity of 431 mAh g
1 after 100 cycles. Sn displays the lowest capacity (148 mAh g
1) among the three samples because of the large volume expansion, repeatedly formed SEI layer and without the matrix-glue. Besides, the SnNi@PEO electrode possesses

Fig. 3 e Diameter distribution of (a) Ni nanospheres, (b) hollow SnNi nanospheres and (c) SnNi@PEO.

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Fig. 4 e XRD patterns of (a) Ni nanospheres, (b) hollow SnNi nanospheres and (c) hollow SnNi@PEO composite.

commendable coulomb efficiency (Fig. 5(a)), which suggests that this electrode has steady SEI film and excellent reversibility. In addition, compared with solid Sn electrode, hollow SnNi electrode shows good capacity retention and rate

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performance, which mainly ascribed to the relatively minor stress changes that confirmed by above lithium-induced stress evolution results. To test the rate capacity, the SnNi@PEO electrode was conducted in various current densities from 100 to 1000 mA g
1. As shown in Fig. 5(b), at 100, 300, 500 and 1600 mA g
1, the SnNi@PEO anode displayed reversible capacities of 847, 628, 505 and 321 mAh g
1, respectively. With the current density backs to 500 mA g
1 and 500 mA g
1, the reversible capacity could recover to 54.6% and 79.2% of the initial capacity (472 mAh g
1 and 677 mAh g
1). This indicates that SnNi@PEO anode can endure tremendous change of current density, which is critical to high power application. To evaluate structural stability, after 100 cycles, the morphologies of both hollow SnNi and SnNi@PEO anode active materials were measured by SEM. As shown in Fig. 6(a), serious agglomerations were observed on the hollow SnNi anode, which may cause the active materials pulverization and poor contacted with current collector. Inversely, as shown in Fig. 6(b), SnNi@PEO electrode basically maintained sphere structure and presented integral particle structure, indicating that the PEO coating can commendably protect structural stability of the active material. This was because that the hollow SnNi spheres are encapsulated by PEO, as membrane

Fig. 5 e (a) Electrodes cycling performance of SnNi@PEO, hollow SnNi nanospheres and Sn nanospheres, (b) Electrodes coulomb efficiency of SnNi@PEO and hollow SnNi nanospheres, (c) rate capability of SnNi@PEO electrode.

Fig. 6 e SEM micrographs of (a) hollow SnNi nanospheres electrode and (b) SnNi@PEO electrode after 100 cycles. Inset of (b) is corresponding high-magnification TEM of SnNi@PEO after 100 cycles.

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Acknowledgements This work was supported by the Natural Science Foundation of China [grant number 51301117 and 51671140]; International Cooperation Project Foundation of Shanxi Province China [grant numbers 201603D421037 and 2015081053]; Higher School Science and Technology Innovation Project Foundation of Shanxi Province, China [grant number 2016128]; and Research Project Supported by Shanxi Scholarship Council of China [grant number 2015-034].

Appendix A. Supplementary data Supplementary data related to this article can be found at http://dx.doi.org/10.1016/j.ijhydene.2017.05.015.

references

Scheme 2 e Schematic diagram of the expansion of nanospheres in charging process.

between electrode and electrolyte solution, avoided direct contact among them and kept the structure integrality [48,49]. We assume that the excellent electrochemical performances of SnNi@PEO may be mainly benefited from the specific architecture. A schematic diagram (see Scheme 2) of the hollow and shell structures illustrates what caused the excellent electrochemical performance. Firstly, the interior void space of hollow structure could relieve extreme volume expansion and mechanical stress in cycling process. Secondly, the PEO layer can not only alleviate the volume expansion of the electrode, but also can prevent the immediate contact among the active material with active material or active material with electrolyte, ensuring to form the stabilized SEI film.

Conclusions In summary, SnNi@PEO were obtained by a galvanic replacement method using Ni nanospheres as the sacrificial template association with surfactant (SDS). As an electrode material for lithium ion batteries, it remarkable meliorates cycling performance compared with hollow SnNi and Sn nanospheres. The excellent electrochemical performance of SnNi@PEO can be ascribed to hollow structure and PEO coating to alleviate volume expansion, guaranteeing the stability of the electrode structure. Therefore, this characteristic structure can meliorate performance of LIBs and becomes promising materials for anode. To further comprehending of the volume expansion, we used a finite element model to simulate the diffusioninduced stress evolution of the single sphere during the cycling process, which lead us to a deeper understanding of stress evolution and the volume expansion during the lithiation process.

[1] Tan C, Qi G, Li Y, Guo J, Wang X, Kong D, et al. Sn-Cu alloy materials with optimized nanoporous structure and enhanced performance for lithium-ion batteries prepared by dealloying. Int J Electrochem Sci 2012;7:10303e12. [2] Feng L, Xuan Z, Ji S, Min W, Zhao H, Gao H. Preparation of SnO2 nanoparticle and performance as lithium-ion battery anode. Int J Electrochem Sci 2015;10:2370e6. [3] Yuan C, Wu HB, Xie Y, Lou XW. Mixed transition-metal oxides: design, synthesis, and energy-related applications. Angew Chem Int Ed 2014;53:1488e504. € se H, Aydin AO, Akbulut H. Free-standing SnO2/MWCNT [4] Ko nanocomposite anodes produced by different rate spin coatings for Li-ion batteries. Int J Hydrogen Energy 2014;39:21435e46. [5] Chang C, Liu S, Wu J, Yang CH. Nano-tin oxide/tin particles on a graphite surface as an anode material for lithium-ion batteries. J Phys Chem C 2007;111:16423e7. [6] Bai Z, Ju Z, Guo C, Qian Y, Tang B, Xiong S. Direct large-scale synthesis of 3D hierarchical mesoporous NiO microspheres as high-performance anode materials for lithium ion batteries. Nanoscale 2014;6:3268e73. [7] Jahel A, Darwiche A, Ghimbeu CM, Vix-Guterl C, Monconduit L. High cycleability nano-GeO2/mesoporous carbon composite as enhanced energy storage anode material in Li-ion batteries. J Power Sources 2014;269:755e9. [8] Zhu YG, Wang Y, Han ZJ, Shi Y, Wong JI, Huang ZX, et al. Catalyst engineering for lithium ion batteries: the catalytic role of Ge in enhancing the electrochemical performance of SnO2(GeO2)0.13/G anodes. Nanoscale 2014;6:15020e8. [9] Hao J, Liu X, Liu X, Liu X, Li N, Ma X, et al. Ionic liquid electrodeposition of Ge nanostructures on freestanding Ninanocone arrays for Li-ion battery. RSC Adv 2015;5:19596e600. [10] Bai Y, Yan D, Yu C, Cao L, Wang C, Zhang J, et al. Core-shell Si@TiO2 nanosphere anode by atomic layer deposition for Liion batteries. J Power Sources 2016;308:75e82. [11] Bai Z, Fan N, Sun C, Ju Z, Guo C, Yang J, et al. Facile synthesis of loaf-like ZnMn2O4 nanorods and their excellent performance in Li-ion batteries. Nanoscale 2013;5:2442e7. [12] Jiang H, Zhou X, Liu G, Zhou Y, Ye H, Liu Y, et al. Freestanding Si/graphene paper using Si nanoparticles synthesized by acid-etching Al-Si alloy powder for highstability Li-ion battery anodes. Electrochim Acta 2016;188:777e84.

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 2 ( 2 0 1 7 ) 1 5 2 9 0 e1 5 2 9 8

[13] Tao H, Xiong L, Zhu S, Yang X, Zhang L. Flexible binder-free reduced graphene oxide wrapped Si/carbon fibers paper anode for high-performance lithium ion batteries. Int J Hydrogen Energy 2016;41:21268e77. [14] Iqbal MZ, Wang F, Zhao H, Rafique MY, Wang J, Li Q. Structural and electrochemical properties of SnO nanoflowers as an anode material for lithium ion batteries. Scr Mater 2012;67:665e8. [15] Lin YM, Abel PR, Gupta A, Goodenough JB, Heller A, Mullins CB. Sn-Cu nanocomposite anodes for rechargeable sodium-ion batteries. ACS Appl Mater Interfaces 2013;5:8273e7. [16] Li Y, Lu X, Wang H, Xie C, Yang G, Niu C. Growth of ultrafine SnO2 nanoparticles within multiwall carbon nanotube networks: non-solution synthesis and excellent electrochemical properties as anodes for lithium ion batteries. Electrochim Acta 2015;178:778e85. [17] Zhao Y, Li X, Dong L, Yan B, Shan H, Li D, et al. Electrospun SnO2-ZnO nanofibers with improved electrochemical performance as anode materials for lithium-ion batteries. Int J Hydrogen Energy 2015;40:14338e44. [18] Woo SW, Okada N, Kotobuki M, Sasajima K, Munakata H, Kajihara K, et al. Highly patterned cylindrical Ni-Sn alloys with 3-dimensionally ordered macroporous structure as anodes for lithium batteries. Electrochim Acta 2010;55:8030e5. [19] Dong QF, Wu CZ, Jin MG, Huang ZC, Zheng MS, You JK, et al. Preparation and performance of nickel-tin alloys used as anodes for lithium-ion battery. Solid State Sci 2004;167:49e54. [20] Uchiyama H, Hosono E, Honma I, Zhou H, Imai H. A nanoscale meshed electrode of single-crystalline SnO for lithium-ion rechargeable batteries. Electrochem Commun 2008;10:52e5. [21] Nithya C, Sowmiya T, Baskar KV, Selvaganeshan N, Kalaiyarasi T, Gopukumar S. High capacity SnxSbyCuz composite anodes for lithium ion batteries. Solid State Sci 2013;19:144e9. [22] Mackay DT, Janish MT, Sahaym U, Kotula PG, Jungjohann KL, Carter CB, et al. Template-free electrochemical synthesis of tin nanostructures. J Mater Sci 2014;49:1476e83. [23] Wang XL, Han WQ, Chen J, Graetz J. Single-crystal intermetallic M-Sn (M ¼ Fe, Cu, Co, Ni) nanospheres as negative electrodes for lithium-ion batteries. ACS Appl Mater Interfaces 2010;2:1548e51. [24] Hou H, Tang X, Guo M, Shi Y, Dou P, Xu X. Facile preparation of Sn hollow nanospheres anodes for lithium-ion batteries by galvanic replacement. Mater Lett 2014;128:408e11. [25] Uysal M, Gul H, Alp A, Akbulut H. Sn-Ni/MWCNT nanocomposite negative electrodes for Li-ion batteries: the effect of Sn:Ni molar ratio. Int J Hydrogen Energy 2014;39:21391e8. [26] Hu RZ, Zeng MQ, Zhu M. Cyclic durable high-capacity Sn/ CuSn composite thin film anodes for lithium ion batteries prepared by electron-beam evaporation deposition. Electrochim Acta 2009;54:2843e50. [27] Farbod B, Cui K, Kalisvaart WP, Kupsta M, Zahiri B. Anodes for sodium ion batteries based on tin-germanium-antimony alloys. ACS Nano 2014;8:4415e29. [28] He M, Walter M, Kravchyk KV, Erni R, Widmer R, Kovalenko M. Monodisperse SnSb nanocrystals for Li-ion and Na-ion battery anodes: synergy and dissonance between Sn and Sb. Nanoscale 2015;7:455e9. [29] Jiang A, Fan X, Zhu J, Ma D, Xu X. Hollow structured Sn-Co nanospheres by galvanic replacement reaction as highperformance anode for lithium ion batteries. Ionics 2015;21:2137e47.

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[30] Gul H, Uysal M, C¸etinkaya T, Guler MO, Alp A, Akbulut H. Preparation of Sn-Co alloy electrode for lithium ion batteries by pulse electrodeposition. Int J Hydrogen Energy 2014;39:21414e9. [31] Yang R, Zhang XJ, Fan TF, Jiang DP, Wang Q. Improved electrochemical performance of ternary Sn-Sb-Cu nanospheres as anode materials for lithium-ion batteries. Rare Met 2014:1e6. [32] Nithyadharseni P, Reddy MV, Nalini B, Kalpana M, Chowdari BVR. Sn-based intermetallic alloy anode materials for the application of lithium ion batteries. Electrochim Acta 2015;161:261e8. [33] Tocoglu U, Cevher O, Guler MO, Akbulut H. Core-shell tinmulti walled carbon nanotube composite anodes for lithium ion batteries. Int J Hydrogen Energy 2014;39:21386e90. [34] Guo B, Shu J, Tang K, Bai Y, Wang Z, Chen L. Nano-Sn/hard carbon composite anode material with high-initial coulombic efficiency. J Power Sources 2008;177:205e10. [35] Egashira M, Takatsuj H, Okada S, Yamaki JI. Properties of containing Sn nanoparticles activated carbon fiber for a negative electrode in lithium batteries. J Power Sources 2002;107:56e60. [36] Lee KT, Jung YS, Oh SM. Synthesis of tin-encapsulated spherical hollow carbon for anode material in lithium secondary batteries. J Am Chem Soc 2003;125:5652e3. [37] Wang K, He X, Ren J, Wang L, Jiang C, Wan C. Preparation of SnSb alloy encapsulated carbon microsphere anode materials for Li-ion batteries by carbothermal reduction of the oxides. Electrochim Acta 2007;52:1221e5. [38] Xie Q, Ma Y, Zhang X, Guo H, Lu A, Wang L, et al. Synthesis of amorphous ZnSnO3-C hollow microcubes as advanced anode materials for lithium ion batteries. Electrochim Acta 2014;141:374e83. [39] Tan C, Qi G, Li Y, Guo J, Wang X, Kong D, et al. The improved performance of porous Sn-Ni alloy as anode materials for lithium-ion battery prepared by electrochemical dissolution treatment. Int J Electrochem Sci 2013;8:1966e75. [40] Yu X, Jiang A, Yang H, Meng H, Dou P, Ma D, et al. Facile synthesis of hollow Sn-Co@PMMA nanospheres as high performance anodes for lithium-ion batteries via galvanic replacement reaction and in situ polymerization. Appl Surf Sci 2015;347:624e31. [41] Fan X, Tang X, Ma D, Bi P, Jiang A, Zhu J, et al. Novel hollow Sn-Cu composite nanoparticles anodes for Li-ion batteries prepared by galvanic replacement reaction. J Solid State Electr 2014;18:1137e45. [42] Yuan C, Zhang L, Hou L, Zhou L, Pang G, Lian L. Scalable room-temperature synthesis of mesoporous nanocrystalline ZnMn2O4 with enhanced lithium storage properties for lithium-ion batteries. Chem Eur J 2015;21:1262e8. [43] Yuan C, Li J, Hou L, Zhang L, Zhang X. Template-free fabrication of mesoporous hollow ZnMn2O4 submicrospheres with enhanced lithium storage capability towards high-performance Li-ion batteries. Part Part Syst Char 2014;31:657e63. [44] Yao Y, Mcdowell MT, Ryu I, Wu H, Liu N, Hu L, et al. Interconnected silicon hollow nanospheres for lithium-ion battery anodes with long cycle life. Nano Lett 2011;11:2949e54. [45] Bai Z, Zhang Y, Zhang Y, Guo C, Tang B, Sun D. MOFs-derived porous Mn2O3 as high-performance anode material for Li-ion battery. J Mater Chem A 2015;3:5266e9. [46] Yang F. Interaction between diffusion and chemical stresses. Mater Sci Eng A 2005;409:153e9. [47] Woodford WH, Chiang YM, Carter WC. “Electrochemical Shock” of intercalation electrodes: a fracture mechanics analysis. J Electrochem Soc 2010;157:A1052e9.

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[48] Han F, Li D, Li WC, Lei C, Sun Q, Lu AH. Nanoengineered polypyrrole-coated Fe2O3@C multifunctional composites with an improved cycle stability as lithium-ion anodes. Adv Funct Mater 2013;23:1692e700.

[49] Chang WS, Park CM, Sohn HJ. Electrochemical performance of pyrolyzed polyacrylonitrile (PAN) based Sn/C composite anode for Li-ion batteries. J Electroanal Chem 2012;671:67e72.