Silicon

Subscriber access provided by UNIV OF CAMBRIDGE

Energy, Environmental, and Catalysis Applications

A Free-standing Sandwich-type Graphene/Nanocellulose/Silicon Laminar Anode for Flexible Rechargeable Lithium-ion Batteries Xiaoming Zhou, Yang Liu, Chunyu Du, Yang Ren, Xiaolong Li, Pengjian Zuo, Geping Yin, Yulin Ma, Xinqun Cheng, and Yunzhi Gao ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b10066 • Publication Date (Web): 09 Aug 2018 Downloaded from http://pubs.acs.org on August 9, 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 20 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 Applied Materials & Interfaces

A Free-standing Sandwich-type Graphene/Nanocellulose/Silicon Laminar Anode for Flexible Rechargeable Lithium-ion Batteries Xiaoming Zhou, †, ‡, # Yang Liu, †, ‡, # Chunyu Du, *, †, ‡ Yang Ren, †, ‡ Xiaolong Li, † Pengjian Zuo, †, ‡ Geping Yin, †, ‡ Yulin Ma, †, ‡ Xinqun Cheng, †, ‡ and Yunzhi Gao †, ‡ †

MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, Harbin Institute of

Technology, Harbin 150001, China. E-mail: [email protected] ‡ Institute

of Advanced Chemical Power Sources, School of Chemistry and Chemical Engineering, Harbin Institute of

Technology, Harbin 150001, China.

ABSTRACT: Freely deformable and free-standing electrodes together with high capacity are crucial to realizing flexible Li-ion batteries. Herein, a lamellar graphene/nanocellulose/silicon (GN/NC/Si) film assembled by interpenetrated graphene nanosheets is synthesized via a facile vacuum-assisted filtration approach accompanied by the covalent cross-linking effect of glutaraldehyde. The hybrid film consists of the highly conductive graphene matrix as an effective current collector, hydroxylated silicon nanoparticles (Si NPs) embedded uniformly within graphene interlayer and nanocellulose as adhesive to crosslink graphene and Si NPs. When applied as anode, the GN/NC/Si film exhibits a high reversible capacity of 1251 mAh g-1 at 100 mA g-1 after 100 cycles and superior rate capability. More importantly, in the stress-strain test, this film represents robust mechanical strength, which not only provides good flexibility but also accommodate volume change of Si during cycling. By coupling with LCO as cathode, the full cell successfully powers a light emitting diode, even bended and folded, indicating the deformation-tolerant GN/NC/Si film electrode for flexible Li-ion batteries. Therefore, the design of layered nanocomposites will offer the possibility closer to the application of flexible batteries.

KEYWORDS: free-standing electrode, graphene nanosheets, nanocellulose, Si-based anode, flexible Li-ion batteries

ACS Paragon Plus Environment

ACS Applied Materials & Interfaces 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 20

INTRODUCTION Flexible and flectional lithium ion batteries are experiencing a thriving development due to the great demand for wearable and flexible electronic devices. The performance of flexible lithium ion batteries relies heavily on the electrode materials.1, 2 Silicon has the highest specific capacity (4200 mAh g-1) so far, and thus is one of the most promising anode materials to meet the increasing requirements of high energy density of flexible lithium ion batteries.3, 4 Nevertheless, its volume expansion and contraction (~300%), unstable solid electrolyte interphase (SEI) films during cycling, and low intrinsic electronic/ionic conductivity result in the deteriorated cycle lifespan, severely restricting the commercial application of Si-based anode.5, 6 Various strategies have been attempted to break through the above bottlenecks in the past two decades. Several researchers set their sights on the critical size of silicon nanoparticles (Si NPs) to suppress their pulverization.7, 8 It is recognized that the critical fracture size of Si NPs as deciphered by in-situ transmission electron microscopy is ~ 150 nm,9 which, however, leads to severe side effects because of the huge specific surface area, hindering the improvement of its electrochemical performance. Recently, porous, 10—13 core-shell 14—17 and yolk-shell 18—21 structures with mesoporous carbon 22, 23 as protective matrixes have become a common tactic to remit the islanding and segregation of Si. Although the cycling stability of these composites is significantly enhanced, the mechanical behavior is still hard to meet the request for flexible batteries. Free-standing paper-like electrodes with light weight, environmental friendliness, recyclability and bendability seem to have a great potential to address pulverization and exfoliation problems by enhancing the mechanical behavior of Si-based anode.24 Graphene (GN) as high conductive backbone, has received more attention to fabricate paper-like electrodes,25 26 since it can be easily functionalized to deposit other components 27, 28 and is conveniently prepared into self-supporting composites using chemical vapor deposition,29 electrodeposition 30 or vacuum filtration. 31, 32 Typically, Luo et al. 33 synthesized a free-standing Si NPs/graphene composite membrane by mixing Si NPs with graphene oxide hydrogel, which presented impressive cycling stability. David et al.

34

fabricated multi-component composite paper

consisting of silicon oxycarbide glass-ceramic particles supported in the reduced graphene oxide matrix and this self-standing anode exhibited a charge capacity of ~588 mAh g-1 at the 1020th cycle. Despite all the progresses in the development of free-standing GN-host films, the dispersion of Si NPs on the graphene layers is still far from satisfactory due to the stubborn aggregation of nano-materials and graphene layers are prone to restack 35 which severely decreases


Page 3 of 20 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


the accessible specific surface area. Besides, the pristine graphene sheets are difficult to form a mechanically sturdy film, thus cannot be practically applied in flexible energy storage systems. Herein, to circumvent above-mentioned obstacles, we present an ultra-flexible, easy-to-scale-up and free-standing GN/NC/Si film with unique laminar conductive networks to imprison the Si NPs for flexible Li-ions batteries. In this strategy, hydroxylation cooperating with covalent cross-linking effect is introduced to eliminate the aggregation of Si NPs and the restack of graphene nanosheets. Glutaraldehyde (GA) as crosslinking agent can generate force to bond Si NPs with graphene nanosheets through hemiacetal structure. Meanwhile, nanocellulose is utilized as a reinforced additive to impart GN films assemblies with mechanical behavior because of its impressive elastic modulus and relying on rich hydroxyl groups, nanocellulose is easily combined with Si NPs by hydrogen bonds. In addition, the abundant porous graphene host in this laminar film not only provides fast electron and ion channels, but also prevents Si NPs from exfoliation during cycling. Also, each graphene layer can be viewed as an electron conductor and current collector, which greatly reduces the isolation of silicon and ensures the utilization of active materials. As a result, the synthesized free-standing GN/NC/Si anode delivers a high reversible capacity of 1251 mAh g-1 after 100 cycles and excellent rate performance. Likewise, an adequate mechanical behavior is exerted in uniaxial tensile tests, and the assembled full-cell still can work under different bending states. This flexible GN/NC/Si film electrode with high capacity opens up a new opportunity to bloom the wearable electronic devices.

RESULTS AND DISCUSSION The free-standing GN/NC/Si film is fabricated through weaving them into a tough thin film (Figure 1). In the process of functionalization, phytic acid with numerous phosphoric acid is selected to modify the surface of Si NPs resulted in the hydroxyl groups-tagged Si NPs. Hydroxylated Si NPs can act as hydrogen bonding acceptors and donors to allow all Si NPs anchored on the graphene/nanocellulose surface containing oxygen-containing groups. 36 Afterward, the GN/NC/Si dispersion was vacuum filtered to form a laminate-structured film. Meanwhile, nanocellulose fibers can strongly reinforce the integrality of the films and the cross-linking reaction of glutaraldehyde further enhances the mechanical behavior of film through hemiacetal structure. Glutaraldehyde, consisting of two aldehyde functional groups, can bond with hydroxyl groups to form covalent cross-linking

37,

which is schematically illustrated in Figure 1b. As shown in

Figure 1c, the characteristic functional groups of functionalized graphene, GA-treated graphene, nanocellulose and cross-linked GN/NC/Si film are detected by Fourier-transform infrared (FT-IR) spectra. The peaks at 878 cm-1 (epoxy rings), 1039 cm-1 (alkoxy C-O), 1148 cm-1 (epoxide C-O), 1587 cm-1 (sp2 carbon C=C), 1715 cm-1 (carbonyl C=O) are



Page 4 of 20

observed in the functionalized graphene comprising oxygen-containing groups. After GA treatment, the new peaks at 2947 and 2859 cm-1 appear, attributed to the C-H stretching in the crosslink molecules. Meanwhile, the peak at 1039 cm-1 (alkoxy C-O) increases, accompanying with decrease of the peak at 1715 cm-1 (carbonyl C=O) owing to the reaction between oxygen-containing functional groups of glutaraldehyde and functionalized graphene. These results clearly confirm the existence of cross-linking reaction. Finally, the excess oxygen-containing groups in this composite film were reduced by hydrazine monohydrate to ensure the excellent electrical conductivity of electrode. Compared with conventional synthetic strategy of composite electrodes, this unique approach, storing Si into the graphene interlayer, has several distinguished advantages: this free-standing GN/NC/Si film eliminates the “inactive ingredients” of binders and ponderous metal current collector as well as reduces contact resistances; 38 more importantly, the interlayer space can buffer the expansion and extraction of Si NPs to prolong cycle life.

Figure 1. (a) Schematic illustration of the preparation procedure (functionalization, filtration and cross-linking for the free-standing film). (b) Schematic illustration of the cross-linking effect. (c) FT-IR spectra of the functionalized GN, GA-treated GN, NC and GA-treated GN/NC/Si film. The overall morphology of GN/NC/Si film, shown in Figure 2a, exhibits a uniform and smooth surface, which is salutary for anode to form a stable SEI layer and reduce the formation of lithium dendrites. The cross sectional SEM image (Figure 2b) of GN/NC/Si film shows typical stratified and porous structure, achieved by the directional flow-induced assembly of graphene sheets during vacuum filtration.39, 40 The thickness of GN/NC/Si film is probably 80 um estimated by a height vernier gauge (inset in Figure 2b). The corresponding elemental mappings (Figure 2c)


Page 5 of 20 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


demonstrate the uniform distribution of silicon, carbon and oxygen elements, indicating that Si NPs are anchored on the surface of graphene and nanocellulose, and have penetrated through the matrix. A closer observation (Figure 2d, e, f) of the cross-section not only reveals the complete sandwich-type structure, but also demonstrates an intimate attachment between Si NPs and graphene. The established 3D graphene matrix can provide an efficient electrical conductive thoroughfare for the interbedded Si NPs. It is worth note that Si NPs, graphene and nanocellulose are confined in the framework without any agglomeration, benefited from a rational preparation process. In contrast, the Si NPs untreated by phytic acid are seriously agglomerate as shown in Figure S1. The SEM and TEM images of nanocellulose (average diameter ~30 nm), as shown in Figure 2g, exhibit a reticular accumulation where the slender nanocellulose fibers are interlaced into a highly yielding network, declaring that nanocellulose takes a key role in forming a flexible substrate. From Figure 2h and 2i, we can clearly observe nanocellulosic entangled fibers, graphene nanosheets and Si NPs of 50-60 nm attached tightly to graphene. The selected area electron diffraction pattern (inset in Figure 2i) displays several diffraction rings, corresponding to (111), (220) and (311) planes of Si, respectively.

Figure 2. (a) SEM surface image and overall photograph of free-standing GN/NC/Si film. (b) Cross sectional SEM image of free-standing GN/NC/Si film (the inset: thickness of GN/NC/Si film). (c) C, O and Si elemental mapping images of free-standing GN/NC/Si film. (d), (e) and (f) Low- and high-magnification cross-sectional SEM images of freestanding GN/NC/Si film. (g) SEM and TEM images of nanocellulose substrate. (h) and (i) TEM and high-resolution TEM of free-standing GN/NC/Si film (the inset: SAED pattern of the Si NPs). ACS Paragon Plus Environment


Page 6 of 20

The XRD analysis, shown in Figure 3a, is implemented to investigate the crystallization characteristics of the GN/NC/Si film. The disappearance of graphite peak at about 26.1°and appearance of peak in 23.6°indicate the graphene are completely transformed from graphite (the detailed comparison of graphene and graphite see Figure S2). The —

diffraction peaks of nanocellulose centered at 14.78°, 16.98°, and 22.7°are related to the (110), (110) and (020) planes, respectively. For silicon, the diffraction peaks at 28.4°, 47.3°, 56.1°, 68.9°, 76.1°and 87.8°can be assigned to the (111), (220), (311), (400), (331) and (422) planes (JCPDS NO. 27-1402), which is consistent with the SAED pattern. Obviously, after vacuum-assisted filtration, these peaks remain intact in the XRD pattern of GN/NC/Si film, demonstrating that the crystalline structure of component is maintained during assembly. Thermogravimetric analysis (TGA) is conducted to determine the content of silicon, nanocellulose and graphene in the composite film (Figure 3b). A total weight of silicon increased (~14%) in the heat process, which is mainly attributed to the oxidation, and meanwhile nanocellulose and graphene are almost completely burnt out. Therefore, the content of silicon in different films is estimated to be 39, 68 and 81 wt%, respectively. In addition, the electrical conductivity of GN/NC/Si films with different contents of silicon are similar with that of GN/NC film (about 38.39 ~ 52.08 S cm-1, see Table S1), which is much higher than previously reported Si anodes, 41, 42 disclosing the outstanding conductivity of our stratified GN/NC/Si films. As shown in Figure 3c and the inset, the BET surface area of GN is 131.5 m2 g-1 and pore-size distribution exhibits a bimodal shape (one peak centers at 2.7 nm and another peak centers at 5.8 nm). After assembling the film, the BET surface area decreases to 9.68 m2 g-1 and pore volume almost disappeared, implying that mutual combination of Si NPs and graphene in the preparation of the multilayered film.43 XPS is carried out to analyze the chemical states in this hybrid film, as shown in Figure 3d-f. The C1s peak can be deconvoluted into three peaks, which are associated with sp2 hybirdized carbon (C-C), C-O and C=O functional groups. For the O1s spectrum, the three peaks centered at 531.5, 532.6 and 533.7 eV, respectively, correspond to the functional groups of C=O, C-O and O=C-O. These C1s and O1s results are consistent with the existence of graphene and nanocellulose in the composite. In addition, the high resolution Si2p spectrum presents two significant peaks at 99.5 and 102-104 eV, which are related to Si0 (pure silicon) and native oxide SiOx, respectively. It has been reported that slight SiOx is able to buffer volume expansion of silicon by generating the inactive phases of Li2O and Li4SiO4 in the first Li-insertion.


Page 7 of 20 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


Figure 3. (a) X-ray diffraction patterns of graphite, GN, Si, NC and free-standing GN/NC/Si film. (b) TGA curves of NC, GN, Si, GN/NC/Si-39, GN/NC/Si-68 and GN/NC/Si-81 composites in air atmosphere from room temperature to 800°C. (c) N2 adsorption-desorption isotherms and pore size distributions of GN and free-standing GN/NC/Si film. XPS spectra of C1s (d), O1s (e) and Si2p (f) in free-standing GN/NC/Si film. The fabricated GN/NC/Si film as anode in half-cell exhibits high specific capacity, good cycling performance and superior rate capability. Figure 4a shows the cyclic voltammetry (CV) curves of GN/NC/Si film anode for first five cycles at a potential scanning rate of 0.1 mV s-1 in the voltage window from 0.005 to 2.0 V. On the first cathodic section, a broad peak within the range of 0.8-1.1 V is associated with formation of SEI, which disappears in the following cycles, implying a stabilized SEI layer. The peak near 0.18 V arises from the 2nd cycle, which is attributed to the formation of metastable amorphous LixSi phases.44 The sharp cathodic peak at 0.01 V close to the cut-off potential is related to the transition from crystalline Si to amorphous LixSi (alloying process). On the anodic section, two broad peaks at around 0.37 V and 0.52 V, which gradually increase current response with cycling due to an activation of Si NPs inserted in the films, are typical dealloying process (LixSi alloys to amorphous Si) during the charge. Figure 4b presents galvanostatic charge-discharge profiles of the first three cycles and tenth cycle of free-standing GN/NC/Si film electrode at a current density of 100 mA g-1. During the initial discharge, a sloping potential plateau from 1.1 to 0.15 V results from the formation of SEI and a long but flat plateau below 0.15 V represents a transformation from crystalline Si to amorphous LixSi. Two couples of redox peaks (0.1 V and 0.3 V during the discharge, 0.25 V and 0.4 V during the charge) in the following cycles reasonably correspond to the alloying and dealloying processes of Si NPs. These charging and discharging potential platforms in galvanostatic charge-discharge profiles are in good agreement with the aforementioned CV curves. The initial charge and discharge capacities are 2606 and 1813 mAh g-1 (based on the



Page 8 of 20

total weight of film anode), meaning the coulombic efficiency of 69.5%. The curves of the 2nd, 3rd and 10th cycles are basically the same, illustrating a stable electrochemical environment around the electrode.

Figure 4. (a) CV curves of the first five cycles of the free-standing GN/NC/Si film at a scanning rate 0.1 mV s-1 in the voltage range of 0.005-2.0 V. (b) Galvanostatic charge-discharge curves of the first three cycles and tenth cycle of the free-standing GN/NC/Si film electrode at a current density of 100 mA g-1 in the voltage range of 0.005-2.0 V (the specific capacity based on the total mass of the anode). (c) Cycling performances of the free-standing film anode with different Si content (GN/NC/Si-39, 68, 81 and nano-Si) from cycle 1 to 100 at a current density of 100 mA g-1 and the corresponding Coulombic efficiency curves (d) Rate capabilities of free-standing GN/NC/Si-68 film at current densities from 0.1 to 6.4 A g-1. (e) EIS Nyquist plots of the free-standing GN/NC/Si-68 film and nano-Si. (f) Schematic illustration the mechanism of lithiation/delithiation in free-standing GN/NC/Si film. Figure 4c displays the cycling performance of film anodes (GN/NC/Si-39, 68, 81) and pristine Si NPs anode prepared by the conventional slurry-casting process. The GN/NC/Si films clearly exhibit superior capacity retention compared to the pristine Si NPs (from 3020 mAh g-1 to 410 mAh g-1 after 40 cycles), verifying the laminar film have the ability to suppress the deterioration of Si-based anode. Although the initial capacity of GN/NC/Si-81 is the highest among the GN/NC/Si film anodes, the attenuation of capacity is more serious after cycles. GN/NC/Si-68 film achieves a quite remarkable improvement in specific capacity and cycling performance, delivering a reversible capacity of 1251 mAh g-1 after 100 cycles. The Coulombic efficiency of GN/NC/Si-39, 68, 81 and nano-Si anodes is 68.5%, 69.5%, 63.9%, 57.3% ACS Paragon Plus Environment

Page 9 of 20 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


in the initial cycle and reaches 98.8%, 99.1%, 98.5%, 98.2% after 100 cycles. The rate performance of the GN/NC/Si-68 is shown in Figure 4d. The specific capacity of 1517 mAh g-1, 1397 mAh g-1, 1271 mAh g-1, 1112 mAh g-1, 940 mAh g-1, 755 mAh g-1 and 405 mAh g-1 is obtained at 0.1 A g-1, 0.2 A g-1, 0.4 A g-1, 0.8 A g-1, 1.6 A g-1, 3.2 A g-1 and 6.4 A g-1, respectively. The specific capacity of 1050 mAh g-1 can be recovered, when the rate is returned back to 0.1 A g-1. The recent literatures about Si/graphene composite and Si/graphene free-standing electrodes are listed in Table S2 for comparing the cycling and rate performance of as-prepared GN/NC/Si film. As we expected, our GN/NC/Si anode is comparable or superior to the previous studies in terms of cycling and rate capability, which can be attributed to the stratified GN/NC/Si structure where the interlaced conductive graphene host provides a sturdy house for protecting Si from islanding and segregation. To highlight this benefit, the morphologies of GN/NC/Si electrode after 100 cycles are examined by SEM and TEM (Figure 5a-d). In Figure 5a, the laminar microstructure with porous characteristics is well maintained. The elements of F, which is generated from the SEI layer, and Si are uniform across the cross-section of the film electrode (Figure 5b). Furthermore, the TEM images of cycled electrode (Figure 5c and 5d) show the integrity of Si NPs with no obvious fractures. These results demonstrate that the laminar structure of the free-standing anode is not destroyed during the charge and discharge processes.

Figure 5. (a) Cross sectional SEM image of the free-standing GN/NC/Si film electrode and (b) the corresponding Si and F elemental mapping images after 100 cycles. (c) and (d) TEM images of the free-standing GN/NC/Si film electrode after 100 cycles. The electrochemical impedance spectroscopy (EIS) test is conducted to analyze anode impedance of GN/NC/Si-68 film and pristine Si NPs. In Nyquist plots (Figure 4e), the semicircle in the high frequency region correspond to the ACS Paragon Plus Environment


Page 10 of 20

charge transfer resistance (Rct) and the incline line in the low frequency region is related to the diffusion of Li ions in the electrode. Rct of Si anode (390.7 ohm) is about twice higher than that of GN/NC/Si-68 film (195.4 ohm). Meanwhile, the Li+ diffusion coefficient of the film anode is 5.7 times larger than that of the Si anode (the detailed calculation process is shown in Figure S3), which can verify our observation of the excellent capability of GN/NC/Si-68 film and also confirms that the interpenetrated graphene plays a crucial role in the hybrid film for reducing the Rct. As shown in Figure 4f, high reversible capacity, excellent rate capability, satisfactory cycle stability of the GN/NC/Si film may result from the following mechanisms: (I) The superior conductive graphene nanosheets serve as an effective electron conductor and current collector (replacing the conventional copper foil) with a stable mechanical structure, preventing the exfoliation of Si nanoparticles. (II) Nanocellulose—the highly flexible and porous material—plays the role of adhesive and crosslinking agent to weave the graphene and Si NPs into tough and pliable cloth, due to its strengthening effect (similar to the steel rebar for reinforcing concrete), great mechanical behavior and hydrophilicity. (III) Nano-silicon is beneficial to transferring Li-ions and shortening diffusion length. If Si NPs unfortunately crack after prolonged lithiation/delitiation, electrons can still be efficiently transported to the fractured Si NPs because they are still tightly trapped on the conductive graphene. (IV) Adequate interlaminar spacing in free-standing sandwich-type Si-based film can accommodate the large volume effect of Si during alloying and dealloying processes. The stress-strain curves of various free-standing films (GN/NC/Si-39, 68 and 81) and GN/NC film, which are detected by static uniaxial tensile instrument (Figure 6a), are presented in Figure 6b to quantify the strength and strain-to-failure. The NC film shows average tensile strength of ~40.3 MPa at a failure strain of 10.3% (Figure S4), verifying that nanocellulose has a high tensile strength for elastic substrates. The GN/NC sample shows average tensile strength of ~16.5 MPa at a strain of 3.3%, while various free-standing films (GN/NC/Si-39, 68 and 81) have average tensile strength of ~11.2, 7.9 and 6.9 MPa at a strain of 2.8%, 2.2% and 1.7%, respectively. In comparison, the pure graphene film cannot be stretched at all by the tensile instrument. Hence, the strength of as-synthesized films is sufficient for a deformable electrode. In addition, such film electrode can be arbitrarily distorted and no fracture is suffered (see Figure 6c), implying the excellent flexibility. To further verify the practicability of GN/NC/Si film anode, we fabricate a flexible battery configuration using LiCoO2 as cathode (a reversible capacity of 123 mAh g-1 after 200 cycles in half CR2025 coin cells, see Figure S5 for details), GN/NC/Si film as anode, as shown in Figure 6d. Figure 6e presents the charge/discharge curve of full cell at a current density of 100 mA g-1 in the voltage window of 1.8-4.2 V and the cycling performance is shown in Figure S6. This full cell exhibits an operating voltage of 3.4 V which is able to power a colored light-emitting diode (yellow, red and green


Page 11 of 20 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


LED, nominal voltage of 3.0 V, 2.0-2.2 V and 1.5 V, respectively), even bended and folded (flat, 45°, 90°, nearly 180° and re-flat, see Figure 6f and S7). The cross-sectional SEM images of unbending and bending states are displayed in Figure 6g and 6h to understand the good mechanical property of GN/NC/Si film. We can observe that the graphene nanosheets are still attached to each other and have only slight irregular overlaps occurrence at the bend, illustrating that the bending has little effect on the film. The totally broken cross-section (Figure 6i) clearly reveals the fracture of GN/NC/Si film, which is similar to a broken rope with dragged filaments (Figure 6j), disclosing that it is the polymer-like ductile-fault fracture produced by the nanocellulose.45

Figure 6. (a) Schematic illustration of the tensile testing of the free-standing GN/NC/Si film. (b) Stress-strain curves of various free-standing film. (c) Optical photographs of GN/NC/Si film under various deformations. (d) Schematic ACS Paragon Plus Environment


Page 12 of 20

diagram of full cell using LiCoO2 as the cathode, GN/NC/Si as the anode. (e) The charge/discharge curve of the single electrodes (LCO cathode, GN/NC/Si anode) and the full cell. (f) Vivid photographs demonstration of the flexibility of the as-fabricated free-standing GN/NC/Si film anode by flat, 45°, 90°, nearly 180°and re-flat. Cross-sectional SEM images of the free-standing GN/NC/Si anode at the unbending (g) and bending (h) states. (i) SEM image of the totally broken cross-section. (j) A broken rope with dragged filaments.

CONCLUSION In this study, we have designed and successfully fabricated a flexible, self-supported and sandwich-type composite film consisting of Si nanoparticles confined in the graphene matrix and nanocellulose acting as robust elastic for the flexible anode of LIBs. Hydroxylation and covalent cross-linking effects are applied to guarantee the well dispersion of Si NPs, as well as the inserted Si NPs act as spacers, effectively eliminating the restacking of graphene sheets. The interpenetrated graphene matrix works as an effective current collector and electronic conductor with robust mechanical strength reinforced further by slender nanocellulose, ensuring the embedded Si NPs can be effectively cycled during charge-discharge process. The resulting GN/NC/Si film anode shows good cycling stability (a high reversible capacity of 1251 mAh g-1 at 100 mA g-1 after 100 cycles) and high rate capacity (405 mAh g-1 at a current density of 6.4 A g-1). Additionally, the assembled full cell manifests good electrochemical stability at serious deformation. This novel GN/NC/Si film takes a promising step closer to the practical flexible free-standing electrode for flexible lithium-ion batteries.

EXPERIMENTAL SECTION Synthesis of functionalized graphene and nanocellulose suspension. The flaky graphite dispersion was synthesized by the shear exfoliation in deionized water (DI water) from expanded graphite (see Figure S8 in Supporting Information) to obtain the uniform thin slices.46 The size distribution curves and SEM images of the exfoliated graphite dispersion were shown in Figure S9, Table S3 and Figure S10. After that, functionalized graphene dispersion (1.0 mg mL-1) was obtained by an improved Hummers method according to the references.47 Nanocellulose fiber pellicle (100 mg, Hainan Yide Foods Co. Ltd. China) was first cut into pieces and dispersed in DI water (100 mL). The mixture was then pulped with a homogenizer at the speed of 10000 rpm to obtain the nanocellulose aqueous suspension (1.0 mg mL-1). Synthesis of graphene/nanocellulose/silicon hybrid film. 40 mg Si nanoparticles (average particle size (APS) ≈ 50


Page 13 of 20 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


nm, Shuitian ST-NANO Science & Technology Co., Ltd, Shanghai, China) were dispersed in 100 mL DI water by sonication for 10 min. Subsequently, 5 mL phytic acid (50%, Aladdin Industrial Inc., Shanghai, China) was added into the Si dispersion by vigorously mechanical agitating for 2 h and ultrasonicating for 30 min. Then, the modified Si NPs were gathered by centrifugation at 10000 rpm and washed several times with DI water to remove the unreacted phytic acid. After that, 20 mg modified Si NPs were respectively re-dispersed in the functionalized graphene dispersion and nanocellulose suspension by stirring for 2 h. The two mixtures were vigorously stirred together for 2 h at room temperature. Finally, a uniform GN/NC/Si dispersion was obtained. The vacuum-assisted filtration was implemented to prepare a laminated film, which was then chemically cross-linked with glutaraldehyde and dried in an oven at 60°C overnight. After drying, the film was reduced by exposure to hydrazine vapor for 3 h. After cooling down, the film was washed with DI water and dried in vacuum oven at 60°C overnight. A series of GN/NC/Si films with various Si contents (39 wt%, 68 wt% and 81 wt%, denoted as GN/NC/Si-39, 68 and 81 film) were obtained in the same way. For comparison, the pristine Si nanoparticles electrode was also prepared through the traditional slurry-casting method. Furthermore, high-temperature calcination was implemented to investigate the mechanical properties of GN/NC/Si film and pure nanocellulose film, as shown in Figure S11. Materials characterization. FT-IR spectra were obtained by IFS-85 (Bruker) spectrometer. The size distribution was determined using the Malvern Mastersizer 2000. The morphology and microstructure of the materials were analyzed by field emission scanning electron microscopy (FESEM, Carl Zeiss MERLIN Compact, Germany) at an accelerating voltage of 10-20 kV, and the energy-dispersive X-ray spectroscopy (EDS) was used to analyze the elemental distribution. Transmission electron microscopy (TEM) and select area electron diffraction (SAED) were conducted on a JEM-2100 TEM instrument at an acceleration voltage of 200 kV. X-ray diffraction (XRD) (Rigaku D/max IIIA, Cu Kα) was carried out to investigate the crystallization characteristics of as-synthesized samples in the 2θ range of 10-90°with a scan rate of 0.05°s-1. Thermal gravimetric analysis was carried out on a Perkin-Elmer TGA 4000 instrument at a 10°C ramp rate from 25°C to 800°C in air flowing. Four-point probe resistivity tester (Four Probes Tech, Guangzhou, RTS-9) was used to detect the electrical conductivity of film. The Brunauer Emmett Teller (BET) surface areas of the samples were determined using a Micromeritics ASAP 2020. X-ray photoelectron spectroscopy (XPS) was recorded by an ESCALab220i-XL electron spectrometer (VG Scientific, 300W Al Kα radiation). Tensile strength test was conducted using Materials Testing Machine (CREE-8007A, Kreui). Electrochemical measurements. Half CR2025 coin cells with Li foil as the counter and reference electrode, the freestanding GN/NC/Si composite film without any binders or conductive additives as the working electrode,



Page 14 of 20

celgard-2400 as separator and 1 M LiPF6 in a mixture of ethylene carbonate (EC)/diethyl carbonate (DEC)/dimethyl carbonate (DMC) (1:1:1) as the electrolyte were assembled in a glove box under argon atmosphere. Galvanostatic charge-discharge cycles were performed by a battery tester (Land CT2001A system). The cyclic voltammetry (CV) curves and electrochemical impedance spectroscopy (EIS) were measured by an electrochemical workstation (CHI660e, Chenhua). The flexibility of full cell was tested by a plastic packaged battery consisted of lithium cobalt oxides (LiCoO2) as the cathode, the freestanding GN/NC/Si composite film as anode, celgard-2400 as separator and 1 M LiPF6 in a mixture of EC/ DEC/ DMC (1:1:1) as the electrolyte. All the tests were conducted at room temperature.

ASSOCIATED CONTENT

Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: Additional experimental section, size distribution, electrical conductivity, XRD, SEM, tensile stress test and electrochemical performance (PDF)

AUTHOR INFORMATION

Corresponding Author *E-mail: [email protected] ORCID Xiaoming Zhou: 0000-0002-9843-9710 Chunyu Du: 0000-0003-0547-7724 Geping Yin: 0000-0002-8804-6550 Author Contributions #X.M.

Zhou and Y. Liu contributed equally to this work.

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT

This work was supported by the Natural Science Foundation of China (No. 51634003), the New Energy Project for Electric Vehicle of National Key Research and Development Program (2016YFB0100206) and the Heilongjiang


Page 15 of 20 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


Science & Technology Key Bidding Program (No. GA14A102).

REFERENCES (1) Liu, W.; Song, M. S.; Kong, B.; Cui, Y. Flexible and Stretchable Energy Storage: Recent Advances and Future Perspectives. Adv. Mater. 2017, 29, 1603436. (2) Balogun, M. S.; Yang, H.; Luo, Y.; Qiu, W.; Huang, Y.; Liu, Z. Q.; Tong, Y. Achieving High Gravimetric Energy Density for Flexible Lithium-Ion Batteries Facilitated by Core–double-shell Electrodes. Energy Environ. Sci. 2018, 11, 1859-1869. (3) Su, X.; Wu, Q.; Li, J.; Xiao, X.; Lott, A.; Lu, W.; Sheldon, B. W.; Wu, J. Silicon-Based Nanomaterials for Lithium-Ion Batteries: A Review. Adv. Energy Mater. 2014, 4, 1300882. (4) Li, J.; Huang, J. A Nanofibrous Polypyrrole/silicon Composite Derived from Cellulose Substance as the Anode Material for Lithium-Ion Batteries. Chem. Commun. 2015, 51, 14590-14593. (5) Liu, X. H.; Wang, J. W.; Huang, S.; Fan, F.; Huang, X.; Liu, Y.; Krylyuk, S.; Yoo, J.; Dayeh, S. A.; Davydov, A. V.; Mao, S. X.; Picraux, S. T.; Zhang, S. L.; Li, J.; Zhu, T.; Huang, J. Y. In situ Atomic-scale Imaging of Electrochemical Lithiation in Silicon. Nat. Nanotechnol. 2012, 7, 749-756. (6) Tritsaris, G. A.; Zhao, K.; Okeke, O. U.; Kaxiras, E. Diffusion of Lithium in Bulk Amorphous Silicon: A Theoretical Study. J. Phys. Chem. C 2012, 116, 22212-22216. (7) Zhou, X; Yin, Y. X.; Cao, A. M.; Wan, L. J.; Guo, Y. G. Efficient 3D Conducting Networks Built by Graphene Sheets and Carbon Nanoparticles for High-Performance Silicon Anode. ACS Appl. Mater. Interfaces 2012, 4, 2824-2828. (8) Liu, X.; Du, Y.; Hu, L; Zhou, X.; Li, Y.; Dai, Z.; Bao, J. Understanding the Effect of Different Polymeric Surfactants on Enhancing the Silicon/Reduced Graphene Oxide Anode Performance. J. Phys. Chem. C 2015, 119, 5848-5854 (9) Liu, X. H.; Zhong, L.; Huang, S.; Mao, S. X.; Zhu, T.; Huang, J. Y. Size-Dependent Fracture of Silicon Nanoparticles During Lithiation. ACS Nano 2012, 6, 1522-1531. (10) Zhang, Z.; Wang, Y.; Ren, W.; Tan, Q.; Chen, Y.; Li, H.; Zhong, Z.; Su, F. Scalable Synthesis of Interconnected Porous Silicon/Carbon Composites by the Rochow Reaction as High-performance Anodes of Lithium Ion Batteries. Angew. Chem. Int. Ed. 2014, 53, 5165-5169.



Page 16 of 20

(11) Wu, H.; Du, N.; Shi, X.; Yang, D. Rational Design of Three-dimensional Macroporous Silicon as High Performance Li-Ion Battery Anodes with Long Cycle Life. J. Power Sources 2016, 331, 76-81. (12) Wang, Y.; Wen, X.; Chen, J.; Wang, S. Foamed Mesoporous Carbon/Silicon Composite Nanofiber Anode for Lithium Ion Batteries. J. Power Sources 2015, 281, 285-292. (13) Du, C.; Gao, C.; Yin, G.; Chen, M.; Wang, L. Facile Fabrication of a Nanoporous Silicon Electrode with Superior Stability for Lithium Ion Batteries. Energy Environ. Sci. 2011, 4, 1037-1042. (14) Zhou, X.; Liu, Y.; Du, C.; Ren, Y.; Mu, T.; Zuo, P.; Yin, G.; Ma, Y.; Cheng, X.; Gao, Y. Polyaniline-encapsulated Silicon on Three-dimensional Carbon Nanotubes Foam with Enhanced Electrochemical Performance for Lithium-Ion Batteries. J. Power Sources 2018, 381, 156-163. (15) Lin, H. Y.; Li, C. H.; Wang, D. Y.; Chen, C. C. Chemical Doping of a Core–shell Silicon Nanoparticles@polyaniline Nanocomposite for the Performance Enhancement of a Lithium Ion Battery Anode. Nanoscale 2016, 8, 1280-1287. (16) Kim, J. S.; Pfleging, W.; Kohler, R.; Seifert, H. J.; Kim, T. Y.; Byun, D.; Jung, H. G.; Choi, W.; Lee, J. K. Three-dimensional Silicon/Carbon Core–shell Electrode as an Anode Material for Lithium-Ion Batteries. J. Power Sources 2015, 279, 13-20. (17) Sun, L.; Wang, X.; Susantyoko, R. A.; Zhang, Q. Copper–Silicon Core–shell Nanotube Arrays for Free-standing Lithium Ion Battery Anodes. J. Mater. Chem. A 2014, 2, 15294-15297. (18) Guo, S.; Hu, X.; Hou, Y.; Wen, Z. Tunable Synthesis of Yolk-Shell Porous Silicon@Carbon for Optimizing Si/C-Based Anode of Lithium-Ion Batteries. ACS Appl. Mater. Interfaces 2017, 9, 42084-42092. (19) Yang, J.; Wang, Y. X.; Chou, S. L.; Zhang, R.; Xu, Y.; Fan, J.; Zhang, W. X.; Kun Liu, H.; Zhao, D.; Xue Dou, S. Yolk-shell Silicon-mesoporous Carbon Anode with Compact Solid Electrolyte Interphase Film for Superior Lithium-Ion Batteries. Nano Energy 2015, 18, 133-142. (20) Ru, Y.; Evans, D. G.; Zhu, H.; Yang, W. Facile Fabrication of Yolk–shell Structured Porous Si–C Microspheres as Effective Anode Materials for Li-Ion Batteries. RSC Adv. 2014, 4, 71-75. (21) Xie, J.; Tong, L.; Su, L.; Xu, Y.; Wang, L.; Wang, Y. Core-shell Yolk-shell Si@C@Void@C Nanohybrids as Advanced Lithium Ion Battery Anodes with Good Electronic Conductivity and Corrosion Resistance. J. Power Sources 2017, 342, 529-536. (22) Liu, Y.; Yu, X. Y.; Fang, Y.; Zhu, X.; Bao, J.; Zhou, X.; Lou, X. W. Confining SnS 2 Ultrathin Nanosheets in Hollow Carbon Nanostructures for Efficient Capacitive .Sodium Storage. Joule 2018, 2, 725-735.


Page 17 of 20 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


(23) Xu, Q.; Sun, J. K.; Yin, Y. X. Guo Y. G. Facile Synthesis of Blocky SiOx/C with Graphite-Like Structure for High-Performance Lithium-Ion Battery Anodes. Adv. Funct. Mater. 2018, 28, 1705235. (24) Yao, B.; Zhang, J.; Kou, T.; Song, Y.; Liu, T.; Li, Y. Paper-Based Electrodes for Flexible Energy Storage Devices. Adv. Sci. 2017, 4, 1700107. (25) Lee, J. K.; Smith, K. B.; Hayner, C. M.; Kung, H. H. Silicon Nanoparticles-graphene Paper Composites for Li Ion Battery Anodes. Chem. Commun. 2010, 46, 2025-2027. (26) Xu, Q.; Sun, J. K.; Li, J. Y.; Yin, Y. X.; Guo, Y. G. Scalable synthesis of spherical Si/C granules with 3D conducting networks as ultrahigh loading anodes in lithium-ion batteries. Energy Storage Mater. 2018, 12, 54-60. (27) Xu, Q.; Sun, J. K.; Yu, Z. L.; Yin, Y. X.; Xin, S.; Yu, S. H.; Guo, Y. G. SiOx Encapsulated in Graphene Bubble Film: An Ultrastable Li-Ion Battery Anode. Adv. Mater. 2018, 30, 1707430. (28) Xu, Q.; Li, J. Y.; Sun, J. K.; Yin, Y. X.; Wan, L. J.; Guo, Y. G. Watermelon-Inspired Si/C Microspheres with Hierarchical Buffer Structures for Densely Compacted Lithium-Ion Battery Anodes. Adv. Energy Mater. 2017, 7, 1601481. (29) Qin, J.; He, C.; Zhao, N.; Wang, Z.; Shi, C.; Liu, E. Z.; Li, J. Graphene Networks Anchored with Sn@Graphene as Lithium Ion Battery Anode. ACS Nano 2014, 8, 1728-1738 (30) Gao, M.; Cui, X.; Wang, R.; Wang, T.; Chen, W. Graphene-wrapped Mesoporous MnCO3 Single Crystals Synthesized by a Dynamic Floating Electrodeposition Method for High Performance Lithium-Ion Storage. J. Mater. Chem. A 2015, 3, 14126-14133. (31) Han, K.; Liu, Z.; Shen, J.; Lin, Y.; Dai, F.; Ye, H. A Free-Standing and Ultralong-Life Lithium-Selenium Battery Cathode Enabled by 3D Mesoporous Carbon/Graphene Hierarchical Architecture. Adv. Funct. Mater. 2015, 25, 455-463. (32) David, L.; Bhandavat, R.; Singh, G. MoS2/Graphene Composite Paper for Sodium-Ion Battery Electrodes. ACS Nano 2014, 8, 1759-1770. (33) Luo, Z.; Xiao, Q.; Lei, G.; Li, Z.; Tang, C. Si Nanoparticles/graphene Composite Membrane for High Performance Silicon Anode in Lithium Ion Batteries. Carbon 2016, 98, 373-380. (34) David, L.; Bhandavat, R.; Barrera, U.; Singh, G. Silicon Oxycarbide Glass-Graphene Composite Paper Electrode for Long-cycle Lithium-Ion Batteries. Nat. Commun. 2016, 7, 10998. (35) Shao, Y.; El-Kady, M. F.; Wang, L. J.; Zhang, Q.; Li, Y.; Wang, H.; Mousavi, M. F.; Kaner, R. B. Graphene-based Materials for Flexible Supercapacitors. Chem. Soc. Rev. 2015, 44, 3639-3665.



Page 18 of 20

(36) Park, M.; Lee, D.; Shin, S.; Kim, H. J.; Hyun, J. Flexible Conductive Nanocellulose Combined with Silicon Nanoparticles and Polyaniline. Carbohydr. Polym. 2016, 140, 43-50. (37) Hu, N.; Meng, L.; Gao, R.; Wang, Y.; Chai, J.; Yang, Z.; Kong, E. S.; Zhang, Y. A Facile Route for the Large Scale Fabrication of Graphene Oxide Papers and Their Mechanical Enhancement by Cross-linking with Glutaraldehyde. 2011, 3, 215-222. (38) Tao, H.; Zhu, S.; Xiong, L.; Zhang, L.; Yang, X. Reduced Graphene Oxide Wrapped Si/C Assembled on 3D N-Doped Carbon Foam as Binder-Free Anode for Enhanced Lithium Storage. ChemistrySelect 2017, 2, 2832-2840. (39) Dikin, D. A.; Stankovich, S.; Zimney, E. J.; Piner, R. D.; Dommett, G. H.; Evmenenko, G.; Nguyen, S. T.; Ruoff, R. S. Preparation and Characterization of Graphene Oxide Paper. Nature 2007, 448, 457-460. (40) Chen, H.; Müller, M. B.; Gilmore, K. J.; Wallace, G. G.; Li, D. Mechanically Strong, Electrically Conductive, and Biocompatible Graphene Paper. Adv. Mater. 2008, 20, 3557-3561. (41) Wang, C.; Wu, H.; Chen, Z.; McDowell, M. T.; Cui, Y.; Bao, Z. Self-healing Chemistry Enables the Stable Operation of Silicon Microparticle Anodes for High-energy Lithium-Ion Batteries. Nat. Chem. 2013, 5, 1042-1048. (42) Son, S. B.; Kim, S. C.; Kang, C. S.; Yersak, T. A.; Kim, Y. C.; Lee, C. G.; Moon, S. H.; Cho, J. S.; Moon, J. T.; Oh, K. H.; Lee, S. H. A Highly Reversible Nano-Si Anode Enabled by Mechanical Confinement in an Electrochemically Activated LixTi4Ni4Si7 Matrix. Adv. Energy Mater. 2012, 2, 1226-1231. (43) Ma, G.; Wang, Z.; Gao, B.; Ding, T.; Zhong, Q.; Peng, X.; Su, J.; Hu, B.; Yuan, L.; Chu, P. K.; Zhou, J.; Huo, K. F. Multilayered Paper-like Electrodes Composed of Alternating Stacked Mesoporous Mo2N Nanobelts and Reduced Graphene Oxide for Flexible All-solid-state Supercapacitors. J. Mater. Chem. A 2015, 3, 14617-14624. (44) Chen, X.; Li, X.; Ding, F.; Xu, W.; Xiao, J.; Cao, Y.; Meduri, P.; Liu, J.; Graff, G. L.; Zhang, J. G. Conductive Rigid Skeleton Supported Silicon as High-performance Li-Ion Battery Anodes. Nano Lett. 2012, 12, 4124-4130. (45) Peng, S. X.; Shrestha, S.; Youngblood, J. P. Crystal Structure Transformation and Induction of Shear Banding in Polyamide 11 by Surface Modified Cellulose Nanocrystals. Polymer 2017, 114, 88-102. (46) Paton, K. R.; Varrla, E.; Backes, C.; Smith, R. J.; Khan, U.; O'Neill, A.; Boland, C.; Lotya, M.; Istrate, O. M.; King, P.; Higgins, T.; Barwich, S.; May, P.; Puczkarski, P.; Ahmed, I.; Moebius, M.; Pettersson, H.; Long, E.; Coelho, J.; O'Brien, SE.; McGuire, E. K.; Sanchez, B. M.; Duesberg, G. S.; McEvoy, N.; Pennycook, T. J.; Downing, C.; Crossley, A.; Nicolosi, V.; Coleman, J. N. Scalable Production of Large Quantities of Defect-free Few-layer Graphene by Shear Exfoliation in Liquids, Nat. Mater. 2014, 13, 624-630.


Page 19 of 20 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


(47) Marcano, D. C.; Kosynkin, D. V.; Berlin, J. M.; Sinitskii, A.; Sun, Z.; Slesarev, A.; Alemany, L. B.; Lu, W.; Tour, J. M. Improved Synthesis of Graphene Oxide. ACS Nano 2010, 4, 4806-4814.



Page 20 of 20

Table of Content


20

Silicon

Recommend Documents