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Rayleigh-Instability-Induced Bismuth Nanorod@NitrogenDoped Carbon Nanotubes as A Long Cycling and High Rate Anode for Sodium-Ion Batteries Pan Xue, Nana Wang, Zhiwei Fang, Zhenxiao Lu, Xun Xu, Liang Wang, Yi Du, Xiaochun Ren, Zhongchao Bai, Shi Xue Dou, and Guihua Yu Nano Lett., Just Accepted Manuscript • DOI: 10.1021/acs.nanolett.8b05189 • Publication Date (Web): 06 Feb 2019 Downloaded from http://pubs.acs.org on February 7, 2019

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Rayleigh-Instability-Induced Bismuth Nanorod@Nitrogen-Doped Carbon Nanotubes as A Long Cycling and High Rate Anode for SodiumIon Batteries Pan Xue, †§ Nana Wang, ‡⊥§ Zhiwei Fang, ⊥ Zhenxiao Lu, † Xun Xu, ‡ Liang Wang, ‡ Yi Du, ‡ Xiaochun Ren, † Zhongchao Bai, †‡⊥* Shixue Dou‡* and Guihua Yu⊥* †

College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan,

Shanxi 030024, P. R. China ‡

Institute for Superconducting and Electronic Materials, University of Wollongong,

Innovation Campus, Squires Way, Wollongong, New South Wales 2500, Australia ⊥

Materials Science and Engineering Program and Department of Mechanical Engineering,The

University of Texas at Austin, TX 78712, USA

ABSTRACT: Sodium-ion battery (SIB) as one of the most promising large-scale energy storage devices has drawn great attention in recent years. However the development of SIBs is limited by the lacking of proper anodes with long cycling lifespans and large reversible capacities. Here we present rational synthesis of Rayleigh-instability-induced bismuth nanorods encapsulated in N-doped carbon nanotubes (Bi@N-C) using Bi2S3 nanobelts as the template for high-performance SIB. The Bi@N-C electrode delivers superior sodium storage performance in half cells, including a high specific capacity (410 mA h g-1 at 50 mA g-1), long cycling lifespan (1000 cycles), and superior rate capability (368 mA h g-1 at 2 A g-1). When 1 ACS Paragon Plus Environment

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coupled with homemade Na3V2(PO4)3/C in full cells, this electrode also exhibits excellent performances with high power density of 1190 W kg-1 and energy density of 119 Wh kg-1total. The exceptional performance of Bi@N-C is ascribed to the unique nanorod@nanotube structure, which can accommodate volume expansion of Bi during cycling and stabilize the solid electrolyte interphase layer and improve the electronic conductivity.

KEYWORDS: Rayleigh instability, bismuth anode, nanotube, sodium-ion batteries

Continuous consumption of fossil fuel and rapidly worsening environmental problems call for high-efficiency and low-cost energy storage systems to stabilize the output of intermittent sustainable energy sources such as wind, sunlight, and tides.1 Although lithium-ion batteries (LIBs) have dominated the portable energy storage market,2-4 the limited resources of lithium in the Earth’s crust and their relatively high price have greatly limited the ongoing development of LIBs for the large-scale energy storage area.5-7 In this regards, sodium ion batteries (SIBs) are attracting increasing attention to supplement the deficiencies of LIBs in the large-scale energy storage field due to the practically inexhaustible nature of sodium sources and their low price.8,9 It is a great challenge, however, to find a suitable Na-storage anode material with high capacity and stable cyclability, because the commercial LIB anode material, graphite, cannot effectively uptake Na+ ions.10,11 Alloy-based materials have drawn great attention as promising anodes for SIBs because their capability for multiple electron transfers results in high theoretical capacity.12-18 Among the alloy-based materials, bismuth has been recently considered as a promising anode for SIBs due to its unique layered crystal structure (with large interlayer spacing (d) along the c-axis, d(003) = 3.95 Å ), which allows easy Na+ insertion/extraction during discharge and charge processes.19 In addition, its working voltage above the voltage for sodium dendrite formation makes it become a safer anode.20 2 ACS Paragon Plus Environment

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Notwithstanding, its low electric conductivity and large volume variation in the alloying/dealloying process is preventing the application of Bi as a practical anode for SIBs. In recent years, considerable efforts have been devoted to solving the problems of poor electrochemical properties for Bi by devising innovative architectures (such as nanowire arrays or alloys, or combining them with carbonaceous materials to improve the conductivity).21-26 For example, Qiu et al. synthesized a bismuth nanosheet composite with C (Bi-NS@C) that maintained a capacity of 106 mA h g-1 at a current density of 200 mA g-1 in SIBs.21 Liu and coworkers synthesized bismuth nanosheets grown on carbon fiber cloth that delivered a reversible capacity of about 240 mA h g-1 at 200 mA g-1.26 Arrays of bismuth nanorod bundle that were synthesized by Feng et al. retained capacity of 301.9 mA h g-1 after 150 cycles at a rate of 50 mA g1 25

. Nonetheless, the electrochemical performance of Bi, especially the cycling stability, is still

far from satisfactory. Thus, designing suitable structures that provide a conductive and buffering matrix for the efficient release of the mechanical stress caused by Na+ insertion/extraction is significantly required. In this work, Bi nanorods@N-doped carbon nanotubes are designed via reduction of Bi2S3 to Bi and carbonization of resorcinol–formaldehyde (RF) layer into nitrogen-doped carbon nanotubes to enable advantageous structural features as high-performance electrodes for SIBs. First, the nitrogen-doped 1D conductive carbon coating can provide short ion/electron diffusion paths, enhance the electrical conductivity, and stabilize the SEI layer formation. Second, the inner void space between the nanorods can buffer the volumetric expansion during the long cycling. As a consequence, the Bi@N-C nanocomposite delivered a high specific capacity (410 mA h g-1 at 50 mA g-1), long cycle life (1000 cycles), and superior rate capability (368 mA h g1

at 2 A g-1) as anode for SIBs. In addition, the performance of Bi@N-C in full cell was first

studied by combining Bi@N-C with homemade Na3V2(PO4)3/C,27 which also exhibited good

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electrochemical performance such as high energy density (119 Wh kg-1total at 1190 W kg-1) and long-term cycling stability (800 cycles). RESULTS AND DISCUSSION

Scheme 1. Schematic illustration of the fabrication process for the Bi@N-C and its working mechanism for SIBs. Scheme 1 illustrates the detailed synthesis route for the 1D Bi@N-C. First, high-quality Bi2S3 nanobelts were fabricated by a solvothermal process according to Reference.28 The synthesized Bi2S3 nanobelts have diameters ranging from 50 nm to 300 nm and lengths up to hundreds of micrometers (Figure S1 in the Supporting Information). On the basis of a fully developed facile polymerization reaction, a RF layer with thickness of ~35 nm was uniformly coated on the surfaces of Bi2S3 nanobelts forming a Bi2S3@RF core-shell structure (Figure S2) (step I, Scheme 1). Subsequently, the Bi2S3@RF was first thermally treated at 350 °C for 2.5 h, and the temperature was then increased to 600 °C for 3 h in hydrogen/argon (5% H2 and 95% Ar) gas to reduce Bi2S3 to Bi and carbonize the RF into nitrogen doped carbon nanotubes (step II, Scheme 1). Considering the large volume shrinkage (43.6%, on the basis of the density ratio 4 ACS Paragon Plus Environment

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of Bi to Bi2S3), one would envisage that the produced cores are Bi nanobelts with a smaller diameter as contrasted to that of their parent precursors. However, the TEM examination reveals that the Bi2S3 nanobelts are reduced to nanorods, which have similar diameters of their parent templates. The nanorods are encapsulated within the new-formed carbon tubes and are randomly separated. This process is agreement well with Cu@Al2O3 nanorod@nanotube structure, which formed by Rayleigh-instability.29 This Rayleigh-instability-induced nanorod@nanotube structure has many advantages when used as electrode for batteries. First, the void space between two nanorods can accommodate the large volume expansion during cycling. Second, the carbon shell can not only protect Bi from self-aggregation during repeated sodiation/desodiation, but also act as part of a conductive network to improve the electronic conductivity of the whole composite. Third, a stable solid-electrolyte interphase (SEI) layer can form on the carbon and enhance the cycling performance. Therefore, the 1D Bi@N-C nanocomposite most likely displays outstanding electrochemical performance, including longterm cycling stability and high rate capability.

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Figure 1. (a) XRD pattern of the Bi@N-C. XPS spectra of Bi@N-C: (b) Bi 4f, (c) C 1s, and (d) N 1s. (e) Low and (f, g) high magnification SEM images of the 1D Bi@N-C. (h) Low and (i) high magnification TEM images of the Bi@N-C. (j) High resolution TEM image of 1D Bi@N-C. (k-k3) Elemental mapping of Bi@N-C. Figure 1a shows the XRD pattern of the synthesized Bi@N-C nanocomposite. All the Xray diffraction (XRD) peaks can be well indexed to Bi (JCPDS No. 44-1246), which demonstrates that Bi2S3 was completely changed into Bi (Figure S3a). Although carbon material is not detected in the XRD pattern, it is clearly observed in the Raman spectrum. As shown in Figure S3b, the Raman peaks located at 1326 cm-1 (D band) and 1600 cm-1 (G band) are the characteristic peaks of carbon.30,31 The carbon content of the sample was determined via thermogravimetric analysis (TGA) (Figure S4a). Based on the XRD pattern, Bi is fully oxidized into Bi2O3 at 750 °C in air (Figure S4b). Therefore, the content of carbon in the composite was determined to be 12.2 wt%. The composition and chemical bonding conditions of the Bi@N-C nanocomposite were further examined by X-ray photoelectron spectroscopy (XPS). The spectrum of Bi 4f (Figure 1b) displays two main peaks assigned to the Bi 4f7/2 (159.3 eV) and Bi 4f5/2 (164.5 eV) orbitals, which belong to the Bi metal.21,32 The spectrum of C 1s (Figure 1c) can be divided into CC/C=C peaks, which are centered at 286.3 eV and 284.7 eV.21 In Figure 1d, the high-resolution N 1s XPS spectrum presented two peaks at 398.2 and 401.9 eV, corresponding to pyridinic N and graphitic N, respectively.33 The N-doped carbon can not only enhance the electronic conductivity but also produces plentiful extrinsic defects and active sites for sodium ion diffusion, which will greatly improve the electrochemical performance of the composite. Figure 1e reveals the microstructure and morphology of the final product by SEM and TEM. The Bi@N-C displays wire-like structures with length of hundreds of micrometres and diameters ranging from 80 nm to 350 nm, which is very similar to the Bi2S3 precursor. Some 6 ACS Paragon Plus Environment

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nanorods inside the nanotubes can be clearly seen in the magnified SEM images (Figure 1f, g), indicating the nanorod@nanotube structural feature. This unique feature is further confirmed by the TEM images. As shown in Figure 1h, the one-dimensional microstructure composed of discontinuous hollow structures and core-shell structures is revealed by the clear contrast. The thickness of carbon shell is about 30 nm (Figure 1i). The high-resolution TEM image of 1D Bi@N-C nanocomposite indicates that the spacing of the lattice fringes of the inner core is about 0.339 nm, which can be identified as reflecting the (211) planes of Bi (Figure 1j). There are no clear lattice fringes in the shell, demonstrating the amorphous nature of the carbon. The elemental mapping of Bi@N-C nanocomposite (Figure 1k-k3) verifies the homogeneous distribution of N atoms in the carbon material. However, the Bi element is characterized by discontinuous confinement in the carbon material, confirming the nanorod@nanotube structural feature.

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Figure 2. The electrochemical performance of the Bi@N-C as anode material for SIBs; (a) CV curves collected at a scan rate of 0.1 mV s-1 for the first three cycles. (b) Discharge/charge profiles for the first 3 cycles at a current density of 0.05 A g-1. (c) Rate performances of Bi nanospheres and Bi@N-C nanocomposite. (d) Cycling stability tests of Bi nanospheres and Bi@N-C nanocomposite at 0.05 A g-1. (e) Long-term cycling stability of Bi nanospheres and Bi@N-C nanocomposite at 1 A g-1. The electrochemical performance of the 1D Bi@N-C nanocomposite as an anode for SIBs was evaluated in the voltage window of 0.1-2.1 V (vs. Na+/Na). Figure 2a displays typical cyclic voltammetry (CV) curves of the 1D Bi@N-C electrode for the first three cycles at a scan rate of 0.1 mV s-1. In the first cathodic scan, a broad and weak peak centered at 0.61 V and a distinct reduction peak located at about 0.46 V are observed, which are due to the formation of 8 ACS Paragon Plus Environment

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the solid electrolyte interphase (SEI) layer and activation of the Bi electrode, respectively.20 In the subsequent anodic process, two obvious peaks (0.64 and 0.77 V) that come from the multistep dealloying of Na3Bi are detected. The ratio of the areas of the two peaks is close to 2: 1, demonstrating the formation of NaBi and Bi. After the first cycle, two peaks are observed around 0.65 V and 0.46 V in the cathodic process, which correspond to the production of NaBi and Na3Bi. 19,20 The two anodic peaks did not change much, however. After the first cycle, the CV peaks almost overlap each other, suggesting the high electrochemical reversibility of the 1D Bi@N-C electrode. Figure 2b shows the initial three charge/discharge profiles of the Bi@N-C anode at a current density of 0.05 A g-1. One small slope and a long plateau are present in the first discharge process, which is very different from the following discharge profiles, which contains two obvious plateaus located at 0.65 V and 0.46 V. The charge profiles are always the same, however, including the first one. Most interestingly, the capacity ratio delivered by the two plateaus is also very close to 1:2. Additionally, the charge and discharge profiles almost coincide with each other after the first cycle, suggesting excellent stability regarding the electrochemical reactions in the charge/discharge process. The initial discharge and charge capacities are 478 mAh g-1 and 410 mAh g-1, respectively, resulting in a Coulombic efficiency of 85.7%. This Bi@N-C nanocomposite has an initial efficiency that is higher than for most of the reported alloying-type anodes and also our synthesized Bi nanospheres (77.7%, Figure S5, S6 and S7), which is highly favorable for the full batteries, especially when the Bi@N-C is used directly as anode without presodiation. 34,35 The rate performance of the 1D Bi@N-C nanocomposite was also investigated at various current densities. As shown in Figure 2c, as the current density increased, the specific capacities is hardly drop , indicating very good rate performance of the sample. It delivered specific capacities of 410 mA h g-1 at 0.05 A g-1, 396 mA h g-1 at 0.1 A g-1, 391 mA h g-1 at 0.4 9 ACS Paragon Plus Environment

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A g-1, 386 mA h g-1 at 0.8 A g-1, 380 mA h g-1 at 1.2 A g-1, 373 mA h g-1 at 1.6 A g-1, and 368 mA h g-1 at 2.0 A g-1. Significantly, when the current density was returned to 0.05 A g-1, a capacity of 410 mAh g-1 was recovered, which reveals that the 1D Bi@N-C nanocomposite can tolerate various rates and keep its structure stable. In comparison, the capacity of Bi nanospheres fades dramatically as the current density is increased.36 When the rate is returned to 0.05 A g-1, the capacity of the nanospheres cannot recover to its initial value because it cannot tolerate the high rate cycling without the protection of carbon materials. The cycling performance of 1D Bi@N-C nanocomposite as anode was first examined at a current density of 0.05 A g-1 (Figure 2d). It retained a capacity of about 400 mAh g-1 after 100 cycles with Coulombic efficiency (CE) of nearly 100 %. In contrast, the Bi nanospheres only kept a capacity of 75 mAh g-1, with continuous capacity fade during the cycling. The long cycling performance at high rate was also investigated, and the results are shown in Figure 2e. After 1000 cycles at the high rate of 1 A g-1, the electrode still maintained a specific capacity of 302 mA h g-1. The capacity of the Bi nanospheres, however, was almost zero after 1000 cycles at the same current density. These results demonstrate that confinement of the Bi in carbon nanotubes not only can improve its rate capability, but also its long-term cycling stability. The carbon nanotube accommodates the volume expansion of the Bi nanorod inside and thus maintains the integrity of the nanocomposite. Simultaneously, the carbon nanotubes improve the electrical conductivity of the electrode during cycling, and confirmed by the Electrochemical Impedance Spectroscopy (Figure S8). More importantly, the Bi@N-C nanocomposite kept its 1D structure after 100 cycles (Figure S9).

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Figure 3. (a) Discharge and charge profiles for the second cycle. (b) XRD patterns of the Bi electrode at each stage labeled in (a). The gradual sodium insertion/extraction of Bi during the second cycle was examined by ex situ XRD (Figure 3). After discharge to 0.61 V in Figure 3a, the Bi is converted to NaBi, as the characteristic diffraction peaks of NaBi appear at 36.8°, 37.5°, 41.3°, and 45.7° (Figure 3b). On further discharge to 0.48 V, the peaks of NaBi become weak, while the peaks of Na3Bi appear. The peaks of NaBi completely disappear on discharge to 0.1 V, and all the peaks correspond to Na3Bi (20.9°, 26.3°, 32.8°, 33.5°, and 47.5°). These results demonstrate that Bi first undergoes sodiation into NaBi, and then to Na3Bi. In the charging process, the XRD patterns show the gradual desodiation of Na3Bi, which first forms NaBi and then returns to the original Bi. Therefore, the presence of two typical plateaus at 0.65/0.77 V and 0.46/0.64 V correspond to the reaction of Bi ↔ NaBi and NaBi ↔ Na3Bi, respectively. This is in total agreement with our CV results. In order to further understand the excellent electrochemical performance of the 1D Bi@N-C nanocomposite, the reaction kinetics were analyzed by CV measurements (Figure S10a). The shape of the CV curves is well preserved with increasing sweep rate from 0.2 to 1.0 11 ACS Paragon Plus Environment

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mV s-1, indicating the characteristic of pseudocapacitive behavior. The redox pseudocapacitive contribution to the capacity of the 1D Bi@N-C nanocomposite electrode was analyzed by separating the capacitive capacity and the diffusion-controlled capacity. The peak current logarithmically plotted against scan rate is shown in Figure S10b, where a linear relation appears. Based on previous reports, a slope of 1.0 reflects the surface capacitive. while the slope of 0.5 reflects the diffusion-controlled contribution (battery process) (k2v1/2).37-39 In this work, the slopes of the anodic peaks (0.77 and 0.64 V) are 0.9648 and 0.7857, and the slopes of the cathodic peaks (0.46 and 0.65 V) are 0.7134 and 0.8573, respectively, which demonstrate a pseudocapacitive process from the typical behaviors of batteries and capacitors. The following equation: i(V) = k1v + k2v1/2 (1) clearly states the contributions of the capacitive capacity and the diffusion-controlled capacity at a fixed potential.40-42 As illustrated in Figure S10c, the pseudocapacitive contribution accounts for 69.3% of the total charge at a scan rate of 0.2 mV s-1. The bar chart (Figure S10d) shows that the capacitive contribution (the filled part) gradually increases with increasing scan rate, indicating that the high rate capability should be attributed to the suppressed diffusion. It is well-known that capacitive behavior stores charges at the surface or near surface, resulting in high power and fast charging/discharging rates. Therefore, the rate performance of 1D Bi@N-C nanocomposite is superior to those in previous reports on Bi based anodes in SIBs (Figure S11), particularly at high current densities.

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Figure 4. Bi@N-C//Na3V2(PO4)3/C Na-ion full cells: (a) CV curves for the first 3 cycles at a scan rate of 0.1 mV s-1. (b) Cycling performance at 1 A g-1 anode (with the capacity calculated by the mass of the anode)( Digital image of the light-emitting diodes lit by the full battery). (c) Rate performance at different rates (with the capacity calculated by the mass of the anode). (d) Ragone plot (energy vs. power density) of this full battery, evaluated by the total mass. The high initial Coulombic efficiency (CE), long cycling stability, and high rate capability of the Bi@N-C nanocomposite prompted us to study its full cell performance. First, the structural details and electrochemical performance of the home-made cathode, Na3V2(PO4)3/C nanocomposite (NVP/C), were examined. The XRD peaks can be well indexed to Na3V2(PO4)3 (JCPDS No. 24-1840) (Figure S12) without any other impurity. The SEM images of the NVP/C sample show that the average size of the irregular particles is about 1.0 μm (Figure S13a and b). The NVP/C powder delivers a reversible capacity of about 105 mA h g-1 after 100 cycles at a current density of 100 mA g-1 in the half cell (Figure S14). The rate performance of NVP/C is also very excellent. Even at the high rate of 3.0 A g-1, it still maintains a capacity of 90 mA h g-1 (Figure S15). The charge/discharge plateaus for NVP/C are at 3.3/3.4 V (Figure S16). 13 ACS Paragon Plus Environment

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After the first cycle activation (Figure 4a), the CV curves overlap each other, indicating very high electrochemical reversibility of the full cell. Moreover, there are two obvious peaks located at around 2.7 V and 2.9 V in the charge cycle (the de-insertion of sodium ions), corresponding to the two peaks around 2.5 and 2.7 V in the discharge process (the insertion of sodium ions). Figure 4b shows the cycling performance of Bi@N-C//NVP/C at a current density of 1 A g1

anode

(with the capacity calculated by the mass of the anode). The reversible capacity can be

still maintained at 240 mA h g-1anode after 800 cycles without presodiation. The capacity loss in the first few cycles might be attributed to the formation of the SEI film and irreversible loss of sodium ions by the NVP/C cathode.43 It can be clearly seen that the light-emitting diodes (LEDs) (2 V, 20 mW) were glowing when a display powered by the full cell was turned on (Figure 4b). Figure S17 shows the charge/discharge voltage profiles of the 1st, 100th, and 800th cycles of the sample, which was cycled between 1.0 and 3.8 V at a current density of 1 A g−1. The charge/discharge voltage profiles barely changed from the 100th to the 800th cycle, indicating that the electrochemical behaviour remained stable. The rate performance of the full cell was high and is shown in Figure 4c. The reversible capacities of Bi@N-C//NVP/C at 0.05, 0.1, 0.4, 0.8, 1.2, 1.6, and 2.0 A g-1 could be maintained at 320, 270, 263, 254, 243, 231, and 223 mA h g-1anode, respectively. Charge/discharge curves at different rates are shown in Figure S18, where the capacity is calculated with respect to the total mass (anode and cathode). With greatly increasing current densities, the voltage plateaus and reversible capacities are found to be slightly reduced. So, the discharge plateau is only reduced a little, indicating the prominent kinetics and small polarization in full cells. As shown in Figure 4d, the energy density is 154 Wh kg-1total at 20 W kg-1. Even at 1190 W kg-1, the energy density of the full cell could still be kept at 119 Wh kg-1total. CONCLUSIONS

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In summary, we have designed a nanoarchitected electrode based on Bi nanorods encapsulated in N-doped carbon nanotubes via a bottom-up confinement strategy. The superior sodium storage performance of Bi@N-C nanocomposite is attributed to its robust highly conductive N-doped carbon coating layer and its unique nanorod@nanotube structure. The electrochemical results demonstrate that Bi@N-C nanocomposite is a promising potential anode material for SIBs with long cycle life. Moreover, this facile synthetic approach allows the advantages of the N-doped carbon coating layer and the unique nanorod@nanotube nanostructure to be applied in the fabrication of other advanced materials in high energy storage systems. ASSOCIATED CONTENT Synthesis method, material characterization, electrochemical measurements, additional XRD patterns, SEM and TEM images. This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author * [email protected] (G.Y.) * [email protected] (S.D.) * [email protected] (Z.B.)

ORCID: Guihua Yu: 0000-0002-3253-0749 Zhongchao Bai: 0000-0001-6023-9900 Author Contributions §

P. X. and N. W. contributed equally to this work.

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ACKNOWLEDGMENT This work was supported by a Research Project from Shanxi Scholarship Council of China (No. 2015-034), the Natural Science Foundation of Shanxi Province of China (201701D221077), the Australian Research Council (ARC) through Discovery Projects (DP160102627) and a Linkage Project (LP160100273), as well as the Welch Foundation Award (F-1861), Alfred P. Sloan Research Fellowship, and Camille Dreyfus Teacher-Scholar Award. REFERENCES (1) Sun, J.; Lee, H. W.; Pasta, M.; Yuan, H.; Zheng, G.; Sun, Y.; Li, Y.; Cui, Y. Nat. Nanotechnol. 2015, 10, 980-985. (2) Armand, M.; Tarascon, J. M. Nature 2008, 451, 652-657. (3) Chen, J.; Cheng, F. Acc. Chem. Res. 2009, 42, 713-723. (4) Zhu, Y.; Peng, L.; Fang, Z.; Yan, C.; Zhang, X.; Yu, G. Adv. Mater. 2018, 30, 1706347. (5) Yabuuchi, N.; Kubota, K.; Dahbi, M.; Komaba, S. Chem. Rev. 2014, 114, 11636-11682. (6) Yan, C.; Lv, C.; Zhu, Y.; Chen, G.; Sun, J.; Yu, G. Adv. Mater. 2017, 29, 1703909. (7) Choi, J. W.; Aurbach, D. Nat. Rev. Mater. 2016, 1, 16013. (8) Li, H.; Peng, L.; Y. Zhu, Chen, D.; Zhang, X.; Yu, G. Energy Environ. Sci. 2016, 9, 33993405. (9) Wang, L.; Wang, C.; Li, F.; Cheng, F.; Chen, J. Chem. Commun. 2018, 54, 38-42. (10) Ong, S. P.; Chevrier, V. L.; Hautier, G.; Jain, A.; Moore, C.; Kim, S.; Ma, X.; Ceder, G. Energ. Environ. Sci. 2011, 4, 3680-3688. (11) Palomares, V.; Serras, P.; Villaluenga, I.; Hueso, K. B.; Carreterogonzález, J.; Rojo, T. Energ. Environ. Sci. 2012, 5, 5884-5901. (12) Luo, W.; Shen, F.; Bommier, C.; Zhu, H.; Ji, X.; Hu, L. Acc. Chem. Res. 2016, 49, 231240. 16 ACS Paragon Plus Environment

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