Green, Scalable and Controllable Fabrication of Nanoporous Silicon

Subscriber access provided by UNIV OF DURHAM

Green, Scalable and Controllable Fabrication of Nanoporous Silicon from Commercial Alloy Precursor for High–Energy Lithium–Ion Batteries Yongling An, Huifang Fei, Guifang Zeng, Lijie Ci, Shenglin Xiong, Jinkui Feng, and Yitai Qian ACS Nano, Just Accepted Manuscript • DOI: 10.1021/acsnano.8b02219 • Publication Date (Web): 23 Apr 2018 Downloaded from http://pubs.acs.org on April 23, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

Green, Scalable and Controllable Fabrication of Nanoporous Silicon from Commercial Alloy Precursor for High–Energy Lithium–Ion Batteries Yongling An,† Huifang Fei,† Guifang Zeng,† Lijie Ci,† Shenglin Xiong,‡ Jinkui Feng,*,† Yitai Qian‡ †

SDU & Rice Joint Center for Carbon Nanomaterials, Key Laboratory for Liquid–Solid

Structural Evolution & Processing of Materials (Ministry of Education), School of Materials Science and Engineering, Shandong University, Jinan 250061, China. E−mail: ([email protected]) ‡

School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, P. R.

China.

ACS Paragon Plus Environment

1

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 32

KEYWORDS silicon, vacuum distillation, nanoporous structure, anodes, lithium–ion batteries ABSTRACT Silicon is considered as one of the most favorable anode materials for the next–generation lithium–ion batteries. Nanoporous silicon is synthesized via a green, facile and controllable vacuum distillation method from the commercial Mg2Si alloy. Nanoporous silicon is formed by the evaporation of low boiling point Mg element. In this method the magnesium metal from the Mg2Si alloy can be recycled. The pore sizes of nanoporous silicon can be commanded by adjusting the distillated temperature and time. The optimized nanoporous silicon (800 oC, 0.5 h) deliveres a discharge capacity of 2034 mA h g–1 at 200 mA g–1 for 100 cycles, a cycling stability with more than 1180 mA h g–1 even after 400 cycles at 1000 mA g–1, and a rate capability of 855 mA h g–1 at 5000 mA g–1. The electrochemical properties might be ascribed to its porous structure which may accommodate large volume change during cycling process. These results suggest that the green, scalable and controllable approach may offer a pathway for the commercialization of high–performance Si anode. This method may also be extended to construct other nanoporous materials.

Silicon is considered as one of the most favorable anode materials for the next–generation lithium–ion batteries (LIBs) with a lower voltage potential (about 0.2–0.3 V vs Li/Li+), abundant resource and high specific capacity (4200 mA h g–1 for Li4.4Si, 3579 mAh g–1 at mild temperature).1–4 However, several key issues hinder its practical application.5–7 The huge volume change (more than 400 %) during the charge/discharge process leads to the cracking and pulverization of silicon anode, resulting in loose contact between current collectors and active


2

Page 3 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

materials companied with everlasting side reactions between silicon anode and electrolyte.8–10 Moreover, the continuous growth of solid electrolyte interface (SEI) layer depletes electrolyte and lithium ions, causing high cell impedance, and finally leading to fast capacity loss, low coulombic efficiency and poor electrochemical performance.11–13 These crucial issues are expected to be relieved by designing suitable nanostructures.14,15 Recently, several silicon nanostructures such as nanotubes,16,17 nanowires,18,19 hollow20,21 and nanoporous structure22,23 have been proved with enhanced electrochemical properties. For example, Kim et al. reported silicon nanotubes with an initial discharge capacity of 2400 mAh g– 1

and a 50% capacity retention after 100 cycles, which attributed to the hollowness of Si

nanotubes that can accommodate a large volume expansion during charge/discharge process.24 Peled et. al. provided crystalline–amorphous core–shell silicon nanowires–based electrodes with a loading of 3–15 mAh/cm2, which also exhibited an enhanced electrochemical performance.25 Silicon–based

electrode

with

porous

structure

displays

outstanding

and

promising

electrochemical performance due to much open channels in such porous structure can act both the volume expansion buffers and the ion pathway.15 Yoon et. al demonstrated the compound of mesoporous Si hollow nanocubes received from the metal–organic framework (MOF) as a electrode with better electrochemical performance.26 However, the state–of–art preparation methods of nanoporous silicon general demand several complex steps, such as depositing a thin film or providing a template, which lead to the preparation expensive and complicated to scale up.15,27 For the mass fabrication of porous silicon in LIBs, the preparation of such porous silicon by a low cost, high output, scalable and simple approach is imperative.28 Yi et al. produced a nano Si, which showed a 1459 mAh g–1 retention capacity of after 200 cycles.29 Wu et al.


3

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 4 of 32

provided a solution process to prepare a 3D network of silicon nanoparticles, which displayed a cycle properties of 550 mAh g–1 after 5000 cycles.30 Dealloying is a general corrosion procedure which the alloy is ‘separated’ by the decidable remove of its elements.31 Chemical dealloying has been studied to provide porous metal by a common corrosion process which dissolves the element from the original alloys to form the 3D successive porous meshwork structure with interconnected ligament.15,31,32 Dealloying reaction can be performed at room temperature and are facile to scale as the alloys are commercially available, which can compose such porous structures with a higher specific surface area.33 Our group has studied the porous Si,28 Ge,34 Bi,35 and Sb36 by a chemical dealloying method. The porous silicon and reduced graphene oxide nanocomposites were prepared by a chemical dealloying method; this porous structure can deliver a discharge capacity of 2280 mAh g–1 and a 85% capacity retention after 100 cycles and a 1521 mAh g–1 discharge capacity at 4000 mA g– 1 28

. However, most of these procedures require pollute chemicals to dissolve component, which

is harmful to the environment and workers. In this work, we explore a green and facile vacuum distillation technique to provide nanoporous silicon (NP–Si) from commercial Mg2Si alloy. The vacuum distillation method is a common process by subliming one or more low boiling point components in the precursor to get the pure high boiling point product.37 The vacuum temperature must be below the melting point of the alloy to form pores and the theoretical basis of the vacuum distillation is the Kirkendall voids and sublimation.38 The continuous NP–Si skeleton could be obtained in a temperature below the melting point of the Mg2Si alloy (1085 oC) via vacuum bumping. In this method the magnesium metal from the Mg2Si alloy can be recycled. The pore size of the NP–Si can be easily controllable by adjusting the distillated temperature and time. The optimized NP–Si (800 oC, 0.5


4

Page 5 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

h) shows an electrochemical capabilities (a discharge capacity of 2034 mA h g–1 after 100 cycles at 200 mA g–1, a discharge capacity of 855 mA h g–1 at 5000 mA g–1, a discharge capacity of 1180 mA h g–1 after 400 cycles at 1000 mA g–1), whereas the commercial nano–silicon shows a poor cycling properties and a worse rate property. These results suggest that the green, scalable and controllable approach may offer a pathway for the commercialization of high–performance Si anode. This method may also be extended to construct other nanoporous materials. Results and Discussion The Mg2Si alloy contains the Mg element with a low boiling point (1107 oC) and the Si element with a high boiling point (2900 oC). The matrix metal (Mg) will undergo sublimation and diffusion to produce voids and eventually form the porous structure.37,38 Figure 1a illustrates the schematic of the evolution of Mg2Si alloy via the vacuum distillated method. The degree of vacuum is set to 10 Pa. Initially, the Mg2Si alloy has an atomically distribution structure (i). When the Mg2Si alloy is distillated at 600 oC, only limited Mg atoms are sublimated (ii). When the distillated temperature is set at 700 oC, more and more Mg atoms are sublimated, and a large number of voids or vacancies can be composed in the Mg2Si alloy (iii). When the distillated temperature is increased to 800 oC, the Mg element is entirely eliminated, and pure NP–Si is obtained (iv). However, when the heat treatment temperature reaches to 900 oC, the pores of NP– Si are reduced (v). The reduced pore value may be ascribed to the growth of silicon crystal at high temperature. Figure 1b–f are the SEM images of Mg2Si alloy in its origin and vacuum distillation conditions at different temperature for 0.5 h. Figure 1b shows the SEM image of the Mg2Si alloy precursor. The XRD pattern of the Mg2Si alloy precursor in Figure 2a fits well with its pure structure (JCPDS, no.35–0773),39,40 which is accordant with the result of the Raman spectra in Figure 2c (Mg–Si).41 Figure 1c shows the SEM of the Mg2Si distillated at 600 oC.


5

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 6 of 32

Compared to the Figure 1b, a rough surface is created, however, the XRD pattern in Figure 2a (600 oC) is nearly unchanged due to only a limited part of Mg element is sublimated. The Raman spectra in Figure 2c (600 oC) is also consist with the XRD result. Figure 1d reveals the SEM images of the evolution structure of the Mg2Si distillated at 700 oC. More and more nanopores are formed because majority of the Mg elements are sublimated at this temperature, compared to the Figure 1c. The XRD pattern (Figure 2a (700 oC)) illustrates the intensity of the peak (111) of pure silicon increased and the Mg2Si peaks greatly reduced, demonstrating most of the Mg atoms are sublimated. This result is in consistence with the Raman spectra in Figure 2c (700 oC). Figure 1e illustrates the SEM image of the Mg2Si distillated at 800 oC. Compared to the Figure 1d, the uniform pores of the porous structure are obtained, as shown in Figure 1e. The interconnected nanopores can facile the lithiation and delithiation to buffer the volume expansion of silicon during the cycling process.28,42 The XRD pattern (Figure 2a (800 oC)) show that the pure silicon is obtained and the Mg content in the Mg2Si alloy are completely removed. The intensity of the XRD pattern is weak, owing to the porous structure of NP–Si, as illustrated in the after TEM results, which may provider to a perfect electrochemical properties.28 The Raman spectra in Figure 2c (800 oC) also reveals that the pure silicon is attained. Figure 1f reveals the SEM image of the Mg2Si distillated at 900 oC. Compared to the Figure 1e, the pores of NP–Si are gradually fused due to the pores partly merge together at the higher temperature.37,38 The XRD pattern in Figure 2a (900 oC) indicates that only the Si atoms are remained in the Mg2Si alloy at 900 oC. The Raman spectra in Figure 2c (900 oC) also confirms that the Mg content in the Mg2Si alloy are completely removed. The successful synthesis of NP–Si with interknitted pores may promote the Li+ insertion and extraction and buffer volume change of silicon anode during the


6

Page 7 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

charge/discharge process. Thus, the promising electrochemical performance of NP–Si can be expected. Moreover, the evolution structures of the Mg2Si alloy by the vacuum distillation method for a longer time (2 h) are also explored. Figure 1g–k, corresponding to Figure 1a, are the SEM images of the structure evolution of Mg2Si alloy using the vacuum distillation method for 2 h, which is accordant to 0.5 h. The XRD (Figure 2b) evolution of Mg2Si distillated for 2 h reveals that the intensity of Mg element is weaker with increasing of vacuum heat temperature from 600 to 800 oC. When the temperature arrives 800 oC, the Mg2Si alloy changes into pure NP–Si. The Raman spectra in Figure 2d also shows that the pure NP–Si is obtained when the temperature increases to 800 oC, which is accordant with the XRD results. Besides, the evolution structure of the Mg2Si distillated for 4 h is also studied, as shown in Figure S1 and S2. Moreover, the EDS results and mapping images of the origin and the vacuum distillation Mg2Si alloy at different conditions are also presented, as shown in Figure S3, S4 and S5. Form these figures, we can see that the Mg2Si alloy changes into pure NP–Si when the temperature reaches to 800 oC. The porous ability of NP–Si at different temperature and time is explored by BET, as shown in Figure 3. Compared to the Mg2Si alloy (Figure S6) of 1.9 m2 g–1, the specific surface area of NP–Si at 800 oC for 0.5 h (Figure 3a) and 2 h (Figure 3b), 900 oC for 0.5 h (Figure 3c) and 2 h (Figure 3d) is about 10.9, 9.8, 9.5 and 8.4 m2 g–1, respectively. The distribution of pore size reveals that the majority of pore diameters is less than 100 nm, and 2–20 nm pore diameters are the majority. These pores may be ascribed to the void space remanent after subliming Mg component in the Mg2Si to develop the NP–Si. The void spaces of various sizes will be beneficial for the transport of lithium ion and more electrolyte–electrode touchs during cycling


7

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 8 of 32

process, accommodate volume expansion and alleviate stress of silicon electrode during the cycling process.8,11,15 Figure 4 provides the HRTEM with the detail structure of Mg2Si alloy by the vacuum distillation at different conditions, which shows a typical nanoporous structure. Compared to the Figure S7 with TME images of the Mg2Si alloy precursor, Figure 4a illustrates the continuous structure of the NC–Si and the porous structure with uniformly distributed pores. Figure 4b reveals the HRTEM image of the NP–Si (800 oC, 0.5 h). The 0.31 nm lattice fringe is commonly perceived, which can be attributed to the (111) crystal planes.11 The corresponding selected area diffraction patterns (Figure 4c) can be ascribed to the silicon with a diamond cubic structure, which is accordant with the result of Figure 4b.15 With the extension of time and the increasing of temperature, the number of pores is reduced, and the aperture of pores is smaller, as shown in Figure 4d (800 oC, 2 h), Figure 4g (900 oC, 0.5 h) and Figure 4j (900 oC, 2 h). The lattice fringe of 0.31 nm (Figure 4e, 4h and 4k) and the selected area diffraction (Figure 4f, 4i and 4l) are also observed, which can be ascribed to the cubic structure of silicon. Moreover, the EDS results, TEM images and corresponding EELS maps of the origin and the vacuum distillation Mg2Si alloy at different conditions are also are studied, as illustrated in Figure S8. These results illustrate the Mg2Si alloy changes into pure NP–Si when the temperature arrives 800 oC, which is accordant with the results of XRD and Raman. The electrochemical performance of NP–Si is explored by the cyclic voltammetry (CV) and static–current charge/discharge cycling using 2016–coin cell with the lithium foil as both the reference electrode and the counter electrode. The electrolyte is 1 M (LiPF6) in EC/DEC (v/v, 1:1), as illustrated in Figure 5. The initial three CV curves of NC–Si (Figure 5a) and NP–Si (800 o

C, 0.5 h, Figure 5b) are executed at a scanning speed of 0.1 mV S–1 between 0.01 V and 3 V.


8

Page 9 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

The CV curves of NP–Si are accordant with the NC–Si, which indicates the identical charge– discharge mechanism. In the first cycle, the cathodic peak between 0.01 and 0.18 V corresponds to the cathodic lithiation of crystalline Si to form LixSi.43,44 The wide oxidation peak appear between 0.1 V−0.53 V, corresponding to the delithiation of LixSi and formation of amorphous silicon, is obviously observed.3 The increased peak area can be ascribed to the gradual activation of silicon anode at rapid CV measurement.3,43,44 Figure 5c and d illustrates the charge/discharge curves of NC–Si (Figure 5c) and NP–Si (Figure 5d) between 0.01 V and 3 V at 200 mA g–1. Both display typical silicon charge/discharge profiles, illustrating the accordant energy storage mechanism, which is accordant with the CV conclusions.43 Specifically, in the initial cycle, compared with a high 85 % coulombic efficiency with of 3412 mA h g–1 discharge capacity of the cell with NP–Si electrode, the cell with NC–Si electrode shows a laigh 76 % coulombic efficiency with a 2569 mAh g–1discharge capacity. The irreversible capacity can be attributed to the irreversible lithium ion in the anode and the formation of SEI.8 The irreversible capacity mainly comes from the formation and deformation of LixSi, a few side reaction, such as sorption and desorption of lithium ion on the electrode surface can also provide capacity.11,15 In the subsequent cycles, compared to the charge/discharge profiles of NC–Si anode, the profiles of NP–Si anode nearly overlap, illustrating the stable cycling performance. The reversible capacity and coulombic efficiency of every cycle of NC–Si and NP–Si electrode are distinctly shown in Figure 5e. After 100 cycles, the discharge capacity of the NC–Si decreases from 2008 mA h g–1 to 274 mA h g–1, which accords with a capacity retention of as low as 13.65 %. The large volume expansion of NC–Si anode causes the capactiy loss during the cycling process.43 In comparison, for the cell with NP–Si, after 100 cycles, the discharge capacity still keeps at 2034 mA h g–1 with a 100 % coulombic efficiency. Besides, the cycling capability of the NP–Si (800 oC for 0.5 h,


9

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 10 of 32

900 oC for 0.5 h and 900 oC for 2 h) at 200 mA g–1 between 0.01 V and 3 V are studied, as shown in Figure S9. As s results, the NP–Si (800 oC, 0.5 h) exhibits a better cycling performance, compared to the NP–Si at other conditions. Expect for the favorable cycling property, the NP–Si (800 oC, 0.5 h) anode also indicates the enhanced rate performance, as shown in Figure 5f. The NC–Si anode is tested at different current densities of 1000, 2000, 3000, 4000 and 5000 mA g–1, the corresponding discharge capacities can be attained at 1235, 420, 130, 25 and 10 mA h g–1, respectively. A discharge capacity of 520 mA h g–1 can be obtained at 1000 mA g–1. For the cell with NP–Si (800 oC, 0.5 h), a discharge capacity of 1715, 1277, 1070, 954 and 855 mA h g–1 can be obtained at the current density of 1000, 2000, 3000, 4000 and 5000 mA g–1. Importantly, a discharge capacity of 1560 mA h g–1 can be attained when the current density returns to 1000 mA g–1. The most outstanding characteristic of the NP–Si electrode is the ultra–steady cycling performance, as illustrated in Figure 5g. After 400 cycles at 1000 mA g–1, there is no obvious capacity depression, corresponding to a 1180 mA h g–1 discharge capacity and an about 100 % coulombic efficiency. The enhanced electrochemical capabilities of NP–Si anode may be ascribed to its special porous structure which could accommodate large volume change and facile ion transport of silicon electrode during cycling process, as illustrated in Figure 6.22,23 To further explore the outstanding capabilities of the NP–Si anode, the charge transfer kinetics measurement (EIS) and ex−situ SEM are executed, as presented in Figure 7. The ex situ SEM of the NC–Si (Figure 7a and c) and NP–Si (Figure 7b and d) anodes that is removed from cells after 100 cycles is explored. From Figure 7a and c we can see cracks and aggregations in the NC–Si electrode, which may result in the disconnection of the active material from current collector, which will lead to the capacity fading.28,45 Nevertheless, no disassembly or cracking (Figure 7b and d) is observed in the NP–Si anode, implying that the NP–Si is robustly anchored on the


10

Page 11 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

anode even after 100 cycles. That is the reason why the NP–Si anode shows such enhanced electrochemical properties compared to the NC–Si anode.46–49 To further explore the mechanism of excellent electrochemical properties of the NP–Si anode, the charge transfer kinetics of the NC–Si (Figure 7e) and NP–Si (Figure 7f) anodes after different cycles at the full delithiation situation are tested by the EIS (electrochemical impedance spectroscopy). In this EIS investigation, the NC–Si and NP–Si anodes are applied for the working electrode and lithium foil as the reference electrode and the counter electrode. The consequences are the distinctive Nyquist plots, which comprise of the flattened semicircle at high and middle frequency space due to surface file impedance and charge transfer resistance, and the straight line at low frequency space ascribing to the diffusion of Li+.28,46 As shown in Figure 7e, the resistance of NC–Si anode sharply increases after 100 cycles. Compared to the NC–Si anode, no obvious impedance change of the NP–Si anode is observed after 100 cycles, as illustrated in Figure 7f, which indicates restricted growth of SEI layer during charge/discharge process.11 Thus, the NP– Si anode illustrates considerably improved electrochemical properties with excellent rate capacity and cycle stability. Conclusion In conclusion, nanoporous silicon is successfully synthesized via a green vacuum distillation method from commercial Mg2Si alloy. The nanoporous silicon is formed by the evaporation of low boiling point Mg element. The pore sizes of nanoporous silicon could be commanded by adjusting the distillated temperature and time. The optimized nanoporous silicon (800 oC, 0.5 h) delivered a discharge capacity of 2034 mA h g–1 after 100 cycles at 200 mA g–1, a cycling stability with more than 1180 mA h g–1 at 1000 mA g–1 even after 400 cycles, and a rate capability of 855 mA h g–1 at the rate of 5000 mA g–1. The electrochemical properties might be


11

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 12 of 32

acribed to its porous structure which could accommodate the large volume change during cycling process. These results suggest that the green, scalable and controllable approach may offer a pathway for the commercialization of high–performance Si anode. This method may also be extended to construct other nanoporous materials. Experimental section Material synthesis:: A commercial Mg2Si alloy (99.5%) was firstly purchased from J&K Chemical and used without further purification. The commercial silicon powder was purchased from the Aladdin company and its SEM was tested (in Figure S10). Then the vacuum distillation experiments were performed at 600 oC, 700 oC, 800 oC, and 900 oC in dynamic high vacuum condition for 0.5 h, 2 h and 4 h, respectively. The vacuum environment was kept under 10 Pa or lower during experimental process. Finally, the nanoporous silicon was obtained. The experiment is handled using the tubular furnace (OTF-1200X-S-II, MTI) in this work. Characterization Methods:: The crystallographic phases of the as–synthesized NP–Si were checked by the power X−ray diffraction (XRD) on a Rigaku Dmaxrc diffractometer at a scanning speed of 10 oC min–1 from 10 oC to 90 oC using Cu Kα radiation (V=50 kV, I=100 mA). The morphology of the as–prepared NP–Si was characterized by the field emission scanning electron microscopy (FESEM, HITACHI SU–70) and high–resolution transmission electron microscope (HRTEM, JEOL JEM–2100). The structure and composition were tested using a JY HR800 spectrometer with a laser spot size of about 1 µm for the Raman spectra. The porous property based on the nitrogen adsorption–desorption isotherms was obtained by Brunauer– Emmett–Teller theory (BET, ASAP 2020).


12

Page 13 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

Electrochemical Measurements: The as–synthesized active materials were mixed with Super P carbon and Polyacrylic acid binder (PAA) binder in the weight ratio of 6:2:2 to form a homogenous slurry, which was coated on a copper foil as a current collector and then dried at 100 °C under vacuum condition for 12 h to form the electrodes. The electrode of nano– crystalline silicon (NC–Si) is also fabricated by the above method. The mass loading of the active material on the NP-Si and NC-Si is about 1.2-1.5 mg/cm2. To measure the electrochemical performance, the 2016–coin cells were assembled using the NP–Si anode as the working electrode, the Li foil as the reference electrode and counter electrode, a Celgard 2400 as the separator,

and

1

M

lithiumhexafluorophosphate

(LiPF6)

in

cosolvent

of

ethylene

carbonate/diethyl carbonate (EC/DEC, 1:1, v/v) as the electrolyte. To standardize the measurement, a fixed amount (about 100 µL) of electrolyte was used in each coin battery. All the cells were installed in a glove box with water and oxygen content lower than 1 ppm and measured at room temperature. Cyclic voltammetry measurements were executed using a CHI 660E electrochemical workstation at a scanning rate of 0.2 mV s–1 between 0.01 V and 3 V (vs. Li+/Li). Galvanostatic discharge/charge cycles were measured on a galvanostatic programmable battery charger between 0.01 V and 3 V (vs. Li+/Li) at the different current density. Electrochemical impedance spectroscopy (EIS) was performed on an electrochemical workstation (CHI 660E, Shanghai China) with a frequency of 100 kHz to 0.01 Hz.


13

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 14 of 32

Figure 1. (a) Schematic of the evolution of Mg2Si alloy by the vacuum distillation method. (i) Initially, the Mg2Si alloy has an atomically structure. (ii) When the Mg2Si alloy is distillated at 600 oC, only limited Mg atoms are sublimated. (iii) More and more Mg atoms are sublimated when the Mg2Si precursor is distillated at 700 oC and a large number of voids or vacancies can be composed in the Mg2Si alloy. (iv) When the heating is increased to 800 oC, the Mg atoms are entirely eliminated, and the pure NP–Si are obtained. (v) When the heat treatment temperature


14

Page 15 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

reaches to 900 oC, the pores of NP–Si are reduced. (b), (g) SEM images of the Mg2Si alloy precursor. (c–f) SEM images of evolution structure of the Mg2Si alloy, distillated by the vacuum distillation method at (c) 600, (d) 700, (e) 800 and (f) 900 oC for 0.5 h, respectively. (h–k) SEM images of evolution structure of the Mg2Si alloy, distillated by the vacuum distillation method at (h) 600, (i) 700, (j) 800 and (k) 900 oC for 2 h, respectively.


15

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 32

Figure 2. (a) XRD and (c) Raman evolution of Mg2Si alloy, distillated by the vacuum distillation method at 600, 700, 800 and 900 oC for 0.5 h, respectively. (b) XRD and (d) Raman evolution of


16

Page 17 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

the Mg2Si alloy, distillated by the vacuum distillation method at 600, 700, 800 and 900 oC for 2 h, respectively.


17

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 32

Figure 3. (a–d) The nitrogen adsorption−desorption isotherm and the corresponding pore size distribution (inset) of Mg2Si alloy, distillated by the vacuum distillation method at 800 oC for (a) 0.5 h and (b) 2 h, 900 oC for (c) 0.5 h and (d) 2 h, respectively.


18

Page 19 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

Figure 4. (a–c) TME (a), High resolution TEM (HRTEM) (b) and selected area electron diffraction (SAED) (c) of the Mg2Si alloy, distillated by the vacuum distillation method at 800 o

C for 0.5 h. (d–f) TME (d), HRTEM (e) and SAED (f) of the Mg2Si alloy, distillated by the

vacuum distillation method at 800 oC for 2 h. (g–i) TME (g), HRTEM (h) and SAED (i) of the Mg2Si alloy, distillated by the vacuum distillation method at 900 oC for 0.5 h. (j–l) TME (j), HRTEM (k) and SAED (l) of the Mg2Si alloy, distillated by the vacuum distillation method at 900 oC for 2 h.


19

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 32

Figure 5. Electrochemical performance of the NC–Si and NP–Si as anode materials between 0.01 V and 3 V (vs Li+/Li). (a, b) Cyclic voltammetry (CV) profiles at the 0.1 mV S−1 of (a) NC– Si and (b) NP–Si (800oC, 0.5 h) anode. (c, d) Galvanostatic charge/discharge voltage curves at


20

Page 21 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

the 200 mA g–1 current density of (c) NC–Si and (d) NP–Si (800oC, 0.5 h) anode. (e) Cycling capability at 200 mA g–1 of NC–Si and NP–Si (800oC, 0.5 h) anode. (f) Rate property at different current densities from 1000 to 5000 mA g–1 of NC–Si and NP–Si (800oC, 0.5 h) anode. (g) Long–term cycling capability at 100 mA g–1 of NP–Si (800oC, 0.5 h) anode.


21

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 32

Figure 6. Schematic of anode design exhibiting a large silicon particle and nanoporous silicon with different porosities. The volume expansion can be accommodated by its porous structure of NP–Si.


22

Page 23 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

Figure 7. (a–d) SEM images. The NC–Si anode (a) before (b) after 100 cycles. The NP–Si anode (c) before (d) after 100 cycles. (e, f) EIS spectra of (e) NC–Si and (f) NP–Si anode before cycle and after 10th cycle, 20th cycle, 50th cycle and 100th cycle.


23

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 32

ASSOCIATED CONTENT Supporting Information. The Supporting Information is available free of charge on the ACS Publications website at DOI: Detailed experimental methods, additional XRD, Raman, SEM, EDS, BET and electrochemical performance. AUTHOR INFORMATION Corresponding Authors *E−mail: [email protected] (J. K. Feng) Author Contributions J. K. Feng conceived the work. Y. L. An, H. F. Fei and G. F. Zeng performed the synthesis, characterization and electrochemical performance tests. Y. L. An wrote this manuscript. J. K. Feng, L. J. Ci, S. L. Xiong and Y. T. Qian polished the manuscript. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by Shandong Provincial Natural Science Foundation (China, ZR2017MB001), Independent Innovation Foundation of Shandong University, The Young Scholars Program of Shandong University (2016WLJH03), The Sate Key Program of National Natural Science of China (No: 61633015, 51532005), 1000 Talent Plan program (No. 31270086963030), The National Natural Science Foundation of China (No. 21371108), the Project of the Taishan Scholar (No.ts201511004). REFERENCES


24

Page 25 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

(1) Obrovac, M. N.; Chevrier, V. L. Alloy Negative Electrodes for Li−Ion Batteries. Chem. Rev. 2014, 114, 11444−11502. (2) Ogata, K.; Salager, E.; Kerr, C. J.; Fraser, A. E.; Ducati, C.; Morris, A. J.; Hofmann, S.; Grey, C. P. Revealing Lithium–Silicide Phase Transformations in Nano−Structured Silicon–Based Lithium Ion Batteries via in Situ NMR Spectroscopy. Nat. Commun. 2014, 5, 3217. (3) Yin, S.; Zhao, D.; Ji, Q.; Xia, Y.; Xia, S.; Wang, X.; Wang, M.; Ban, J.; Zhang, Yi.; Metwalli, E.; Wang, X.; Xiao Y.; Zuo, X.; Xie, S.; Fang, K.; Liang, S.; Zheng, L.; Qiu, B.; Yang, Z.; Lin, Y.; Chen, L.; Wang, C.; Liu, Z.; Zhu, J.; Müller−Buschbaum, P.; Cheng, Y.−J. Si/Ag/C Nanohybrids with in Situ Incorporation of Super−Small Silver Nanoparticles: Tiny Amount, Huge Impact. ACS Nano 2018, 12, 861−875. (4) Gao S.; Su J.; Wei X.; Wang M.; Tian M.; Jiang T.; Wang Z. Self−Powered Electrochemical Oxidation of 4−Aminoazobenzene Driven by a Triboelectric Nanogeneratortor. ACS Nano, 2017, 11, 770−778. (5) Liu, S.; Xia, X.; Zhong, Y.; Deng, S.; Yao, Z.; Zhang, L.; Cheng, X.; Wang, X.; Zhang, Q.; Tu, J. 3D TiC/C Core/Shell Nanowire Skeleton for Dendrite–Free and Long–Life Lithium Metal Anode. Adv. Energy Mater. 2017, 8, 1702322. (6) Zhong. Y.; Chao, D.; Deng, S.; Zhan. J.; Fang. R.; Xia. Y.; Wang, Y.; Wang. X.; Xia. X.; Tu. J. Confining Sulfur in Integrated Composite Scaffold with Highly Porous Carbon Fibers/Vanadium Nitride Arrays for High–Performance Lithium–Sulfur Batteries. Adv. Funct. Mater. 2018, 1706391. (7) Magasinski, A.; Dixon, P.; Hertzberg, B.; Kvit, A.; Ayala, J. High−Performance Lithium−Ion Anodes Using a Hierarchical Bottom−up Approach. Nature Mater. 2010, 9, 353–358.


25

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 26 of 32

(8) Gao S.; Chen Y.; Su J.; Wang M.; Wei X.; Jiang T.; Wang Z. Triboelectric Nanogenerator Powered Electrochemical Degradation of Organic Pollutant Using Pt−Free Carbon Materials. ACS Nano, 2017, 11, 3965−3972. (9) Zuo, X.; Xia, Y.; Ji, Q.; Gao, X.; Yin, S.; Wang, M.; Wang, X.; Qiu, B.; Wei, A.; Sun, Z.; Liu,

Z.;

Zhu,

J.;

Cheng,

Y.

Self−Templating

Construction

of

3D

Hierarchical

Macro−/Mesoporous Silicon from 0D Silica Nanoparticles. ACS Nano 2017, 11, 889−899. (10) Zhang, X.; Qiu, X.; Kong, D.; Zhou, L.; Li, Z.; Li, X.; Zhi, L. Silicene Flowers: A Dual Stabilized Silicon Building Block for High−Performance Lithium Battery Anodes. ACS Nano 2017, 11, 7476−7484. (11) Liang, J.; Li, X.; Hou, Z.; Zhang, W.; Zhu, Y.; Qian, Y. A Deep Reduction and Partial Oxidation Strategy for Fabrication of Mesoporous Si Anode for Lithium Ion Batteries. ACS Nano 2016, 10, 2295−2304. (12) Tang, H.; Tu, J.; Liu, X.; Zhang, Y.; Huang, S.; Li, W.; Wang, X.; Gu, C. Self–Assembly of Si/Honeycomb Reduced Graphene Oxide Composite Film as a Binder–Free and Flexible Anode for Li–ion Batteries. J. Mater. Chem. A 2014, 2, 5834–5840. (13) Zhong, Y.; Xia, X.; Deng, S.; Zhan, J.; Fang, R.; Xia, Y.; Wang, X.; Zhang, Q.; Tu, J. Popcorn Inspired Porous Macrocellular Carbon: Rapid Puffing Fabrication from Rice and Its Applications in Lithium–Sulfur Batteries. Adv. Energy Mater. 2018, 8, 1701110. (14) Cho, W.; Kim, H. J.; Lee, H. I.; Seo, M. W.; Ra, H. W. 5L−Scale Magnesio−Milling Reduction of Nanostructured SiO2 for High Capacity Silicon Anodes in Lithium−Ion Batteries. Nano Lett. 2016, 16, 7261−7269.


26

Page 27 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

(15) Wada, T.; Ichitsubo, T.; Yubuta, K.; Segawa, H.; Yoshida, H.; Kato, H. Bulk−Nanoporous−Silicon Negative Electrode with Extremely High Cyclability for Lithium−Ion Batteries Prepared Using a Top−Down Process. Nano Lett. 2014, 14, 4505–4510. (16) Park, M.; Kim, M. G.; Joo, J.; Kim, K.; Kim, J.; Ahn S.,; Cui, Y.; Cho, J. Silicon Nanotube Battery Anodes. Nano Lett. 2009, 9, 3844–3847. (17) Yoo, J. K.; Kim, J.; Jung, Y. S.; Kang, K. Scalable Fabrication of Silicon Nanotubes and Their Application to Energy Storage. Adv. Mater. 2012, 24, 5452–5456. (18) Bogart, T. D.; Oka, D.; Lu, X.; Gu, M.; Wang, C. Lithium Ion Battery Peformance of Silicon Nanowires with Carbon Skin. ACS Nano 2014, 8, 915–922. (19) Liu, N.; Hu, L.; Mcdowell, M. T.; Jackson, A.; Cui, Y. Prelithiated Silicon Nanowires as an Anode for Lithium Ion Batteries. ACS Nano 2011, 5, 6487–6493. (20) Ma, H.; Cheng, F.; Chen, J. Y.; Zhao, J. Z.; Li, C. S.; Tao, Z. L.; Liang, J. Nest−like Silicon Nanospheres for High−Capacity Lithium Storage. Adv. Mater. 2007, 19, 4067–4070. (21) Yao, Y.; Mcdowell, M. T.; Ryu, I.; Wu, H.; Liu, N. Interconnected Silicon Hollow Nanospheres for Lithium−Ion Battery Anodes with Long Cycle Life. Nano Lett. 2011, 11, 2949– 2954. (22) Dai, F.; Zai, J.; Yi, R.; Gordin, M. L.; Sohn, H.; Chen, S.; Wang, D. Bottom−up Synthesis of High Surface Area Mesoporous Crystalline Silicon and Evaluation of Its Hydrogen Evolution Performance. Nat. Commun. 2014, 5, 3605. (23) Wang, W.; Kumta, P. N. Nanostructured Hybrid Silicon/Carbon Nanotube Heterostructures: Reversible High−Capacity Lithium−Ion Anodes. ACS Nano 2010, 4, 2233−2241.


27

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 32

(24) Du, F.; Ni, Y.; Wang, Y.; Wang, D.; Ge, Q.; Chen, S.; Yang, H. Green Fabrication of Silkworm Cocoon−Like Silicon−Based Composite for HighPerformance Li−Ion Batteries. ACS Nano 2017, 11, 8628−8635. (25) Peled, E.; Patolsky, F.; Golodnitsky, D.; Freedman, K.; Davidi, G. Tissue−Like Silicon Nanowires−Based Three−Dimensional Anodes for High−Capacity Lithium Ion Batteries. Nano Lett. 2015, 15, 3907−3916. (26) Yoon, T.; Bok, T.; Kim, C.; Na, Y.; Park, S.; Kim, K. S. Mesoporous Silicon Hollow Nanocubes Derived from Metal−Organic Framework Template for Advanced Lithium−Ion Battery Anode. ACS Nano 2017, 11, 4808–4815. (27) Shen, T.; Xia, X.; Xie, D.; Yao, Z.; Zhong, Y.; Zhan, J.; Wang, D.; Wu, J.; Wang, X.; Tu, J. Encapsulating Silicon Nanoparticles into Mesoporous Carbon Forming Pomegranate–Structured Microspheres as a High–Performance Anode for Lithium Ion Batteries. J. Mater. Chem. A 2017, 5, 11197–11203. (28) Feng, J.; Zhang, Z.; Ci, L.; Zhai, W.; Ai, Q.; Xiong, S. Chemical Dealloying Synthesis of Porous Silicon Anchored by in Situ Generated Graphene Sheets as Anode Material for Lithium−Ion Batteries. J. Power Sources 2015, 287, 177–183. (29) Vrankovic, D.; Graczyk−Zajac, M.; Kalcher, C.; Rohrer, J.; Becker, M.; Stabler, C.; Trykowski, G.; Albe, K.; Riedel, R. Highly Porous Silicon Embedded in a Ceramic Matrix: A Stable High−Capacity Electrode for Li−Ion Batteries. ACS Nano 2017, 11, 11409−11416. (30) Wu, H.; Yu, G.; Pan, L.; Liu, N.; Mcdowell, M. T.; Bao, Z.; Cui, Y. Stable Li−Ion Battery Anodes by in−Situ Polymerization of Conducting Hydrogel to Conformally Coat Silicon Nanoparticles. Nat. Commun. 2013, 4, 1943.


28

Page 29 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

(31) Erlebacher, J.; Aziz, M. J.; Karma, A.; Dimitrov, N.; Sieradzki, K. Evolution of Nanoporosity in Dealloying. Nature 2001, 410, 450–453. (32) Snyder, J.; Asanithi, P.; Dalton, A. B.; Erlebacher, J. Stabilized Nanoporous Metals by Dealloying Ternary Alloy Precursors. Adv. Mater. 2008, 20, 4883–4886. (33) Yu, H. D.; Regulacio, M. D.; Ye, E.; Han, M. Y. Chemical Routes to Top−Down Nanofabrication. Chem. Soc. Rev. 2013, 42, 6006–6018. (34) Liu, S.; Feng, J.; Bian, X.; Qian, Y.; Liu, J. Nanoporous Germanium as High−Capacity Lithium−Ion Battery Anode. Nano Energy 2015, 13, 651–657. (35) Liu, S.; Feng, J.; Bian, X.; Liu, J.; Xu, H. Advanced Arrayed Bismuth Nanorod Bundle Anode for Sodium−Ion Batteries. J. Mater. Chem. A 2016, 4, 10098–10104. (36) Liu, S.; Feng, J.; Bian, X.; Liu, J.; Xu, H. The Morphology−Controlled Synthesis of a Nanoporous−Antimony Anode for High−Performance Sodium−Ion Batteries. Energy Environ. Sci. 2016, 9, 1229–1236. (37) Sun, Y.; Ren, Y.; Yang, K. New Preparation Method of Micron Porous Copper through Physical Vacuum Dealloying of Cu–Zn alloys. Mater. Lett. 2016, 165, 1–4. (38) Sun, Y.; Ren, Y. New Preparation Method of Porous Copper Powder through Vacuum Dealloying. Vacuum 2015, 122, 215–217. (39) Roberts, G. A.; Cairns, E. J.; Reimer, J. A. Magnesium Silicide as a Negative Electrode Material for Lithium−Ion Batteries. J. Power Sources 2002, 110, 424–429. (40) Liu, Y.; Ma, R.; He, Y.; Gao, M.; Pan, H. Synthesis, Structure Transformation, and Electrochemical Properties of Li2MgSi as a Novel Anode for Li−lon Batteries. Adv. Funct. Mater. 2014, 24, 3944–3952.


29

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 30 of 32

(41) Schmuelling, G.; Winter, M.; Placke, T. Investigating the Mg−Si Binary System via Combinatorial Sputter Deposition as High Energy Density Anodes for Lithium−Ion Batteries. ACS Appl. Mater. Inter. 2015, 7, 20124–20133. (42) Li, X.; Chen, Q.; McCue, I.; Snyder, J.; Crozier, P.; Erlebacher, J.; Sieradzki, K. Dealloying of Noble−Metal Alloy Nanoparticles. Nano Lett. 2014, 14, 2569–2577. (43) Kovalenko, I.; Zdyrko, B.; Magasinski, A.; Hertzberg, B.; Milicev, Z.; Burtovyy, R.; Luzinov. I.; Yushin, G. A Major Constituent of Brown Algae for Use in High−Capacity Li−Ion Batteries. Science 2011, 334, 75–79. (44) Liu, N.; Lu, Z.; Zhao, J.; Mcdowell, M. T.; Lee, H. W.; Zhao. W. T.; Yi, C. A. Pomegranate−Inspired Nanoscale Design for Large−Volume−Change Lithium Battery Anodes. Nature Nanotech. 2014, 9, 187–192. (45) Zhan, J.; Deng, S.; Zhong, Y.; Wang, Y.; Wang, X.; Yu, Y.; Xia, X.; Tu, J. Exploring Hydrogen Molybdenum Bronze for Sodium Ion Storage: Performance Enhancement by Vertical Graphene Core and Conductive Polymer Shell. Nano Energy 2018, 44, 265–271. (46) Pang, C.; Cui, H.; Yang, G.; Wang, C. Flexible Transparent and Free−Standing Silicon Nanowires Paper. Nano Lett. 2013, 13, 4708–4714. (47) Zheng X.; Su J.; Wei X.; Jiang T.; Gao S.; Wang Z. Self−Powered Electrochemistry for the Oxidation of Organic Molecules by a Cross−Linked Triboelectric Nanogenerator. Adv. Mater. 2016, 28, 5188−5194. (48) Gao S.; Geng K.; Liu H.; Wei X.; Zhang M.; Wang P.; Wang J. Transforming Organic-Rich Amaranthus Waste into Nitrogen-Doped Carbon with Superior Performance of Oxygen Reduction Reaction. Energy & Environmental Science, 2015, 8(1):221−229.


30

Page 31 of 32 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

(49) Choi, S.; Kwon, T. W.; Coskun, A.; Choi, J. W. Highly Elastic Binders Integrating Polyrotaxanes for Silicon Microparticle Anodes in Lithium Ion Batteries. Science 2017, 357, 279–283.


31

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 32 of 32

Table of Contents Image


32

Green, Scalable and Controllable Fabrication of Nanoporous Silicon

Recommend Documents