Encapsulating MnSe nanoparticles inside 3D hierarchical carbon

Subscriber access provided by UNIV OF CAMBRIDGE

Energy, Environmental, and Catalysis Applications

Encapsulating MnSe nanoparticles inside 3D hierarchical carbon frameworks with lithium storage boosted by in-situ electrochemical phase transformation Tao Yang, Jianwen Liu, Manshu Zhang, Dexin Yang, Jianhui Zheng, Zhijin Ju, Jianlin Cheng, Jinyang Zhuang, Yangai Liu, Jiasong Zhong, Hao Liu, Guoxiu Wang, Rongkun Zheng, and Zaiping Guo ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.9b10961 • Publication Date (Web): 19 Aug 2019 Downloaded from pubs.acs.org on August 19, 2019

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 35 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

Encapsulating MnSe Nanoparticles inside 3D Hierarchical Carbon Frameworks with Lithium Storage Boosted by Insitu Electrochemical Phase Transformation Tao Yang1,2,3, #, Jianwen Liu2, 4 #, Manshu Zhang5, #, Dexin Yang1, Jianhui Zheng6, Zhijin Ju6, Jianlin Cheng6, Jinyang Zhuang5, Yangai Liu5, *, Jiasong Zhong1, Hao Liu7, Guoxiu Wang7, Rongkun Zheng3, *, Zaiping Guo2, 4, * 1 College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310036, People’s Republic of China 2 Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials & Ministry of Educational Key Laboratory for the Synthesis and Application of Organic Functional, Molecules & College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, People’s Republic of China 3 School of Physics, the University of Sydney, NSW 2006, Australia 4 Institute for Superconducting & Electronic Materials, University of Wollongong, NSW 2522, Australia 5 School of Materials Science and Technology, Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, China University of Geosciences, Beijing 100083, People’s Republic of China 6 College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou 310014, People’s Republic of China 7 School of Chemistry and Forensic Science, University of Technology Sydney,

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

Sydney, NSW 2007, Australia # These authors contributed equally to this work.

Abstract: Electrode materials that act through the electrochemical conversion mechanism, such as metal selenides, have been considered as promising anode candidates for lithium-ion batteries (LIBs), although their fast capacity attenuation and inadequate electrical conductivity are impeding their practical application. In this work, these issues are addressed through the efficient fabrication of MnSe nanoparticles inside porous carbon hierarchical architectures for evaluation as anode materials for LIBs. Density functional theory (DFT) simulations indicate that there is a completely irreversible phase transformation during the initial cycle, and the high structural reversibility of β-MnSe provides a low energy barrier for the diffusion of lithium ions. Electron localization function calculations demonstrate that the phase transformation leads to high charge transfer kinetics and a favorable lithium ion diffusion coefficient. Benefitting from the phase transformation and unique structural engineering, the MnSe/C chestnut-like structures with boosted conductivity deliver enhanced lithium storage performance (885 mAh g–1 at a current density of 0.2 A g-1 after 200 cycles), superior cycling stability (a capacity of 880 mAh g–1 at 1 A g-1 after 1000 cycles), and outstanding rate performance (416 mAh g–1 at 2 A g-1). Keywords: MnSe; MOFs; Lithium-ion batteries; Anode; Electrochemical performance


Page 2 of 35

Page 3 of 35 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


Introduction Thanks to their long cycling lifespan, high energy density, low self-discharge feature, secure operating voltage, and lack of a memory effect, lithium-ion batteries (LIBs) have been extensively employed in our modern life, such as in portable electronic devices

1-4.

Current LIBs are insufficient, however, in fulfilling the ever-

growing demands of large-scale applications, including electric vehicles, hybrid vehicles, and the emerging smart grids

3, 5-7.

As the foremost characteristics of LIBs,

their energy density and cycling life must be upgraded and improved. As the commercially accepted anode material for LIBs, graphite has a limited theoretical capacity (~372 mAh g-1) and unsatisfactory rate capability, so that it cannot meet the demands of large-scale energy applications, although it has various advantages, such as high cycling stability, high Coulombic efficiency, and natural abundance 8. Thus, pursuing novel anode candidates to satisfy the uninterrupted growth of requirements is still a critical need for researchers. Recently, a handful of researchers have paid close attention to the fundamental investigation of transition metal chalcogenides (TMDs) as anode materials for LIBs, owing to their high theoretical capacities and good chemical stability 9-14. Among these potential candidates, Mn-based chalcogenides have aroused widespread academic interest due to their widespread availability and nontoxicity 15-18. Nowadays, MnS with various nanostructures has been investigated due to its electrochemical properties and lithiation/delithiation mechanism, whereas there are few reports about MnSe as an anode material for lithium ion batteries 18-21. Fu et al. first prepared α-MnSe thin films



Page 4 of 35

through reactive pulsed laser deposition and then found that it delivered 472 mAh g−1 after 120 cycles 22. Rock salt MnSe nanostructures synthesized by Du et al. via a hot injection synthesis strategy displayed an initial discharge capacity of 790 mAh g−1 with a corresponding 50.8 % Coulombic efficiency (CE) for the first cycle

17.

Although

MnSe has comparable physicochemical characteristics to MnS, MnSe still experiences quick capacity degradation during long-term cycling, due to serious electrode pulverization and failure of electronic connections resulting from severe volumetric change due to the conversion mechanism. What is more, the intrinsic electrical conductivity should also be improved, although its value is higher than those of Mnbased oxides and sulfides. To mitigate these difficulties, an accepted efficient strategy for improving the electrochemical performance of anode materials is to rationally construct carbon-coated three-dimensional porous hierarchical architectures. The void space, the numerous pores, and the carbon matrix in the hierarchical structures can effectively alleviate the huge volumetric changes. The nanosized particles shorten the pathways for lithium ion diffusion, while the pervasively conductive carbon network makes the fast transportation of lithium ions and electrons possible. The combination of these advantages consequently induces superior cycling stability and excellent rate performance. As a result, exploring a facile approach for the fabrication of threedimensional (3D) MnSe/C hierarchical micro/nanostructures is imperative. Metal-organic frameworks (MOFs), as a class of novel porous materials with varying elemental composition, a periodic pore structure, and controllable morphology, have been employed as effective templates/precursors to achieve functional materials


Page 5 of 35 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


with great performance. Intensive attention has been drawn to the generation of porous carbon materials

23-25,

metal oxides/carbon

26-29,

metal sulfides/carbon

5, 13, 30-31,

and

metal phosphides/carbon composites 32-33. Nevertheless, there are few reports about the controllable fabrication of metal selenides/carbon composites with the combined features of high specific surface area and homogeneous micro/mesoporous structures. Notably, with growth under controllable confinement and an in-situ selenization procedure, metal selenide nanoparticles can be homogeneously embedded in pervasive carbon networks without a continuous increase in particle size, which is beneficial for improving the rate performance and cycling performance of batteries. These features are difficult for other approaches to achieve. Although recent reports have realized great success in promoting the electrochemical stability and energy density of metal selenide/carbon materials

34-38,

these MOFs-derived strategies regarding 3D

hierarchical architectures have been rarely attained. Notwithstanding a tremendous amount of effort, to the best of our knowledge, there has no triumph with respect to the synthesis of 3D MnSe/C hierarchical composites derived from metal-organic frameworks that can meet the growing requirements for LIBs with better electrochemical performance. Herein, we have designed a general strategy to construct three kinds of 3D hierarchical architectures employing manganese 1,3,5-benzenetricarboxylate (MnBTC) for the templates. These structural designs are inspired by the chestnut, echinops latifolius, and myrica rubra, respectively. Notably, a completely irreversible phase transition (α → β) during the electrochemical reaction at the initial cycle was detected.



Density functional theory (DFT) simulations indicated that the completely irreversible phase transformation during the initial cycle and the high structural reversibility of βMnSe provide a lower energy barrier for the diffusion of lithium ions than α-MnSe. The electrochemical impedance spectroscopy (EIS) results indicated that the irreversible phase transition boosted the lithium ion diffusion and reduced the charge-transfer resistance of the electrodes. What is more, in these hierarchical architectures, the combined effects of various advantages, including pseudocapacitive behavior, large specific surface area, shortened diffusion channels, enough void space, and fast electron transfer led to excellent electrochemical performance of all three samples. Specifically, among these three samples, the chestnut-like rock-salt-type MnSe/C delivered the highest reversible capacity of 885 mAh g–1 at 0.2 A g-1 and a capacity of 880 mAh g–1 at a rate of 1 A g-1 after 1000 cycles as anode material for LIBs. They also exhibited excellent rate performance (416 mAh g–1 at 2 A g-1), thereby rendering these asobtained α‑MnSe/C hierarchical architectures viable for energy storage. Experimental section Synthesis of Mn-BTC chestnut-like, echinops latifolius-like, and myrica rubra-like structures. For the chestnut-like structures, in a typical process, 10 mmol of manganese acetate tetrahydrate and 7.5 g of polyvinylpyrrolidone (PVP K-40) were dissolved in a mixture of 75 ml absolute ethyl alcohol and 75 ml distilled water (denoted as solution A). Simultaneously, 13.4 mmol trimesic acid was dissolved in the mixture in the same proportion (denoted as solution B). After that, solution B was added into solution A dropwise under magnetic stirring for 10 min. After 5 h, the precipitates were


Page 6 of 35

Page 7 of 35 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


centrifuged and washed several times with a mixture of distilled water and ethanol (EtOH). The products were dried overnight at 80 °C in an oven (denoted as MBTC1). For comparison, the Mn-BTC echinops latifolius-like structures (denoted as MBTC2) were also synthesized by a similar fabrication procedure, in which the solvent was changed to a mixture of 25 ml N, N-dimethylformamide (DMF), 25 ml ethyl alcohol, and 25 ml distilled water (DW). In addition, the Mn-BTC myrica rubra-like structures (denoted as MBTC3) were also achieved by employing a mixture of 50 ml absolute ethyl alcohol and 50 ml distilled water as the solvent, where the content of PVP K-40 was 3.2 g. Synthesis of α-MnSe/C chestnut-like, echinops latifolius-like, and myrica rubra-like structures. For the generation of the α-MnSe/C chestnuts (denoted as MS1), 500 mg of the MnBTC1 and 1 g of Se powder were separately put into two porcelain boats and then placed them into a tubular furnace before being heated at 600 °C for 2 h under N2 atmosphere. Meanwhile, the MBTC2 and MBTC3 were also individually selenized through a similar synthetic process (with the final samples denoted as MS2 and MS3, respectively). Material characterizations The crystal structures of the as-obtained samples were identified through a Bruker D8-Advance X-ray diffraction (XRD) system equipped with a Cu Kα source (λ = 1.542 Å) at room temperature. The absorption spectra were recorded on a Fourier transform infrared spectrometer (FT-IR, PerkinElmer Spectrum 100). Nitrogen adsorption-desorption isotherms and Brunauer-Emmett-Teller surface areas were



acquired by an Autosorb iQ Station 2 instrument at 77 K. The pore size distribution was calculated through the Barrett–Joyner–Halenda (BJH) method. The morphology of the samples was examined by a Carl Zeiss Ultra field-emission scanning electron microscopy (FESEM) unit with energy dispersive spectroscopy (EDS) and a JEOL 2200 TEM microscope. The transmission electron microscope (TEM) images, highresolution TEM (HRTEM) images, and high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) images and the corresponding energy dispersive X-ray spectroscopy (EDX) mapping analyses were collected on a JEOL-2010 with an accelerating voltage of 200 kV. Raman spectra were obtained by utilizing a Renishaw inVia Reflex Raman spectroscopy system with a laser wavelength of 532 nm. Cell preparation and electrochemical measurements The working electrodes were obtained by homogeneously mixing 80 wt% assynthesized materials, 10 wt% carbon black, and 10 wt% carboxymethyl cellulose binder (CMC) in distilled water. After blade casting the above-mixed slurry onto copper foil, these electrodes were dried at 80 °C for 12 h under vacuum and then punched into disks. The mass loading of the as-prepared electrode was 1.8–2.0 mg cm−2. CR 2032 coin-type cells were assembled to evaluate the electrochemical performance with lithium foil as the reference and counter electrode, Celgard 2340 membrane as the separator, and a solution of 1 M LiPF6 in a 1:1 (v/v) mixture of ethylene carbonate and dimethyl carbonate as the electrolyte. These cells were assembled in an argon-filled glove box (H2O, O2 < 0.1 p.p.m). Galvanostatic discharge/charge measurements were


Page 8 of 35

Page 9 of 35 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


acquired on a Land CT2001A multichannel battery testing system at the designated current densities within a voltage window of 0.01–3.00 V (vs. Li/Li+). Cyclic voltammetry (0.01–3.00 V) and electrochemical impedance spectroscopy (EIS) tests were conducted on an electrochemical workstation (CHI660E) at constant room temperature. Computational details All the calculations were performed using the Vienna Ab initio Simulation Package (VASP)

39-40.

The electron-ion interactions were described by projector

augmented wave method (PAW)41-42 pseudopotentials with the Perdew-BurkeErnzerhof generalized gradient approximation functional 43. Optimization convergence criteria were set to 10-4 eV for electronic self-consistent iterations and 0.03 eV for ionic relaxation loops. The plane wave basis sets had a cut-off energy of 350 eV. The Brillouin zone was sampled by 2×2×2 special k-points using the Monkhorst–Pack scheme 44. We used a 2×2×2 supercell to simulate the diffusion of a Li atom in the βMnSe (α-MnSe) bulk, using the climbing nudged elastic band (NEB) method 45. We calculated the electron localization function (ELF) and according to previous studies on Mn-based compounds

46-47,

the Hubbard U value for Mn-d orbitals was set at 4.2

eV. Results and discussion Figure 1 schematically illustrates the fabrication process for three unique αMnSe/C structures derived from Mn-MOFs. Rational design of these hierarchical MnBTC architectures was achieved by the coprecipitation method through changing the



solvent and the content of PVP. Then, these MOFs were subsequently transformed into α-MnSe/C porous structures through an in-situ selenization method. In this process, manganese ions were converted to manganese selenide, and the organic ligands were simultaneously turned into carbon networks and coated on the metal selenides. Notably, the rational design of hierarchical architectures is beneficial for enlarging the surface area of active materials, promoting close contact with the electrolyte, and shortening lithium ion diffusion channel, thereby expediting the transportation of Li ions and achieving enhanced electrochemical kinetics. Structural information on MBTC1, MBTC2, and MBTC3 was derived from their XRD patterns (Figure S1a in the Supporting Information), where all the signal peaks were agreement with the previous reports. From the Fourier transform infrared (FTIR) spectra, the characteristic peaks centered at around 1617, 1374, and 756 cm−1 are in accordance with the reported data for the asymmetric stretching vibration and the symmetrical stretching vibration of -COO-, and the plane vibration of benzene core rings that have substituted for the linking molecules in the MOF, respectively. The characteristic peaks observed at 3600–3000 cm−1 refer to ν (OH) in the water molecules in the MOF precursors. Scanning electron microscopy (SEM) was employed to analyze the morphological characteristics of the MOF precursors. As illustrated in Figure 2a, the MBTC displayed chestnut-like structures with good uniformity. The enlarged SEM image revealed that numerous rotating triangular nano-prisms with smooth surfaces had assembled into the final 3D hierarchical architectures that had a size of around 4 μm (Figure 2b and 2c).


Page 10 of 35

Page 11 of 35 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 case of the MBTC2 precursor, the echinops latifolius-like structures consisted of interconnected nanowires and displayed a smaller average size (about 2 μm) (Figure 2 d-f). The Mn-BTC myrica rubra-like structures (Figure 2g-i) presented inferior homogeneity in terms of size and its triangular nano-prism substructures were densely packed. After in-situ selenization at 600 °C for 2 h, as shown in Figure 3, the macroscopic structure of the three as-prepared samples was preserved unchanged. Actually, the substructures for these three samples experienced great changes, as revealed by close observation. In the MS1 sample, the triangular nano-prisms were transformed into nanorods and became rough due to numerous nanoparticles on their surfaces (Figure 3a). In the case of the MS2 sample, the substructures were well retained, but there were also plenty of nanoparticles attached to the nanowires. The surface of the MS3 sample became disjointed with plentiful pores. The structural information was also further confirmed through transmission electron microscopy (TEM), as shown in Figure 4. There are numerous nanodots in the interiors of the nanorod-like structures with a small amount of large grains (about 40 nm) on the surface, as shown in Figure 4a, in accordance with the above highmagnification SEM image. Further insight into the nanorod-like structures revealed that all the nanoparticles were distributed in the carbon networks. The carbon network incorporating the α-MnSe nanoparticles can impede the agglomeration of nanoparticles caused by high surface energy and simultaneously alleviate the strain resulting from the volumetric effect during repeated cycling. Carbon networks are also pivotal in



providing operative pathways for speedy electron transport and subsequently boosting the electronic conductivity of the active materials. Furthermore, distinct lattice fringes can be observed in the high-resolution TEM (HRTEM) image, pointing to interplanar spacing of 0.273 nm, which can be attributed to the (200) planes of α-MnSe (Figure 4c). This result demonstrates the successful generation of crystallized manganese selenide nanoparticles after in-situ selenization. Energy-dispersive X-ray spectroscopy (EDX) elemental mapping analysis was employed to confirm the chemical composition and elemental distribution in the MS1 sample, and the corresponding results are shown in Figure 4d. The elemental mapping image clearly reveals that the Mn, Se, and C element were all evenly distributed in the whole substructure. To further investigate the crystal structure, typical X-ray diffraction (XRD) was conducted, and the corresponding results are shown in Figure S2a. As expected, all the XRD patterns of the three samples exhibited six diffraction peaks centered at 28.3°, 32.8°, 47.0°, 58.5°, 68.7°, and 78.2°, which can be assigned to the (111), (200), (220), (222), (400), and (420) plane reflections of α-MnSe, respectively. Raman analysis was also utilized to assess the structures of the three samples. As revealed in Figure S2b, the Raman spectra of the three samples showed two obvious peaks located at 1590 and 1350 cm−1, corresponding to the G-band of sp2 graphite carbon and the D-band of sp3disordered carbon, respectively. The calculated intensity ratios (ID/IG) for the three samples were 0.82, 0.69, and 0.67, respectively, indicating a slightly higher quantity of disordered carbon and extrinsic defects in the MS1 sample, which is credited with promoting better electronic conduction. The surface areas and pore-size distributions


Page 12 of 35

Page 13 of 35 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


of the three samples were also derived through nitrogen adsorption-desorption isotherms and Brunauer-Emmett-Teller (BET) analysis (Figure 4c and 4d). The MS1 sample had a higher surface area of 112 m2 g−1, whereas the surface areas of the MS2 and MS3 samples were 82 and 78 m2 g−1, respectively. Additionally, all the similar pore size distributions derived by the Barrett-Joyner-Halenda (BJH) method manifested micro- and mesoporous features. The three samples as anode materials for LIBs were meticulously evaluated. The cyclic voltammograms (CVs) of the MS1 electrodes recorded at 0.1 mV s−1 between 0.01 and 3 V are displayed in Figure 5a. In the initial cycle, there are three cathodic peaks, among which, the weak peak at 1.95 V is related to Li-ion insertion into the lattice of α-MnSe and the subsequent generation of intermediate phase LixMnSe. The weak peak appearing at 0.46 V corresponds to the formation of the solid electrolyte interphase (SEI) film, whereas the strong peak centered at 0.15 V during the cathodic process can be assigned to the formation of Mn metal and Li2Se. Two oxidation peaks at around 1.17 V and 2.33 V can be detected during the initial charging process, demonstrating that the electrochemical oxidation process proceeds by two steps. This phenomenon was also observed in the previously reported α-MnS-based electrodes 16, 19.

In the second cycle, there is no reduction peak at 0.46 V, revealing the generation of

a stable SEI layer. In the meantime, a new reduction peak is identified at about 0.29 V, which can be indexed to the generation of Mn and Li2Se. The voltage increase may be ascribed to the structural transformation during the first cycle. Notably, from the second cycle, the CV curves are almost superimposed, indicating the high reversibility of the



MS1 sample

48.

Page 14 of 35

The electrochemical reactions in the MS1 electrode during the

discharge/charge process can be described according to the conversion mechanism with the intermediate phase LixMnSe: α-MnSe + xLi + xe- → LixMnSe

(1)

LixMnSe + 2e− ⇌ Mn + Li2Se

(2)

Mn + Li2Se ⇌ β-MnSe

(3)

Figure 5b presents the charge-discharge profiles of theMS1 electrode at a current density of 0.2 A g−1 in the voltage range from 0.01 to 3 V. The initial discharge capacity and charge capacity were 1059 and 651 mAh g−1, respectively, with 61% Coulombic efficiency (CE), higher than for the MS2 and MS3 electrodes (59% and 56%, respectively) The irreversible capacity loss can be assigned to the inevitable construction of the SEI layer, which is prevalent in most anode materials

49-50.

In the

second cycle, the CE value rises to 94%, showing the excellent reversibility of the MS1 electrode. Figure 5c displays a comparison of the cycling performances of these three electrodes and of Mn-BTC. For MS1 electrodes, a specific capacity of 885 mAh g−1 with nearly 100% Coulombic efficiency (CE) was maintained at 0.2 A g-1 after 200 cycles. The MS2 and MS3 electrodes also delivered comparable capacity and similar cycling stability (657 mAh g−1 and 580 mAh g−1 after 200 cycles, respectively). The Mn-BTC electrode, however, only delivered a specific capacity of 260 mAh g−1 after 200 cycles. Notably, the phenomenon of continuously increasing capacity was detected for MS1, MS2, and MS3 electrodes. This phenomenon can be commonly detected in metal-based materials used as anode electrodes, which can be assigned to the


Page 15 of 35 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


progressive activation of anode materials with numerous meso- or micropores during repeated cycling, the gradual construction of electroactive polymeric gel-like films, interfacial lithium storage, or the reversible generation and degeneration of a secondary electrolyte interface phase (LiOH, LiH, or Li2O)

4, 51-52.

More importantly, the MS1

electrode also presented superior rate performance to those of the MS2 and MS3 electrodes. As shown in Figure 5d, satisfactory average specific capacities of 716, 661, 587, 522, and 416 mA h g−1 at 0.1, 0.2, 0.5, 1, and 2 A g−1 were recorded. After ten cycles at a high current rate, a reversible capacity of 751 mAh g −1 was achieved when the specific current was returned to 0.1 A g−1, which is slightly higher than initial reversible capacity. The cycling stability of the electrodes at a high current density (1 A·g−1) was also investigated, and the results are presented in Figure 5e. The reversible capacities of all these three electrodes, in common with the trend tested at the low current rate (0.2 A g−1), experienced a continuous increase. For the MS1 electrode, the reversible capacity still maintained the high value of 880 mA h g−1, while those of MS2 and MS3 were 453 and 541 mA h g−1 after 1000 cycles at 1 A·g−1, respectively. These results effectively demonstrate the advantages of the bio-inspired hierarchically structures as LIB anode materials. In order to further interpret the dynamic behavior of the as-prepared materials in redox processes as LIB anodes, quantitative analysis, such as from CV curves of the corresponding electrodes, was conducted at various scanning rates (v, mV s-1). Figure 6a-f exhibits the result for the MS1, MS2, and MS3 electrodes at scan rates from 0.1 to



Page 16 of 35

0.6 mV s-1, respectively. Although the current density was boosted with the increasing scan rate, the peak current was nonlinear with respect to the value of v1/2, revealing that the lithium storage mechanism of these electrodes consists of both diffusion-controlled electrochemical reactions and a capacitive process. It is widely accepted that the capacitive process in the electrodes could promote better electrochemical performance, and the corresponding mechanism could be evaluated according to the following equations 53-58: i = a vb

(4)

log(i) = b log(b) + log(a)

(5)

where i represents the recorded peak current, a is a parameter, v refers to the sweep rate, and b is the slope of log(v) versus log(i). A b value of 0.5 indicates that the electrochemical mechanism is diffusion-dominated, whereas the current is controlled by non-Faradaic capacitive behavior if b = 1.0. By fitting, the adjustable parameter b was calculated, and all the values for the reduction and oxidation peaks in MS1 electrodes were higher than 0.5, demonstrating that the electrochemical kinetics was based on a combination of diffusion behavior and pseudo-capacitive behavior. As presented in Figure 6b, 6d, and 6f, all the b values of the corresponding peaks for MS1 electrodes were larger than those for MS2 and MS3 electrodes, indicating that the capacitance behavior made a greater contribution to lithium storage for the electrode. The galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) were introduced to elucidate the differences in physicochemical properties for the three electrodes. According to the GITT tests carried


Page 17 of 35 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


out on a battery tester, the apparent lithium ion diffusion coefficients (D) could be revealed based on the equation: D app, Li = 4L2ΔEs2/πτΔEt2

(6)

where L represents the ion diffusion length (or the thickness of electrode for compact electrodes), ΔEs corresponds to the steady-state potential change due to the current pulse, τ is the relaxation time (s), and ΔEt represents the potential change (V) during the constant current pulse after eliminating the iR drop (Figure S3). Figure 7a presents the GITT results for the three electrodes after 5 cycles at 0.2 A g−1. The MS1 electrode displayed the highest average lithium ion diffusion coefficient. According to the EIS results shown in Figure 7b, the three electrodes after 60 cycles presented similar Nyquist plots. The suppressed semicircle in the medium- and high-frequency range reveals the charge-transfer process, whereas the straight line in the low-frequency range can be attributed to the Warburg behavior. According to the results, the MS1 electrode perceptibly demonstrated smaller resistance and higher charge transfer kinetics than the MS2 and MS3 electrodes. As is well known, the lithium ion diffusion coefficients of the three electrodes could be evaluated by the following formula: D = R2T2/2A2n4F4C2σ2

(7)

Z’ = RΩ + Rct +σω-1/2

(8)

where R denotes the gas constant, T represents the absolute temperature (K), F stands for the Faraday constant, A is the surface area of the electrode, n is the number of electrons involved during the process of Li+ ion transportation, C signifies the molar concentration of Li+ ions, and σ is the Warburg factor, which is determined by the slope



of the real part of the impedance (Z′) versus the square root of the radial frequency (ω1/2)

(ω = 2πf). Therefore, according to the equation, a high slope value implies a low ion

diffusion coefficient. Indeed, the MS3 electrode presented the highest slope value, indicating the lowest ion diffusion coefficient. The small slope value in the MS1 electrode also denoted high transportation of lithium ions, resulting in enhanced reversible capacity and rate performance, which agreed with the above electrochemical performance test. Additionally, the EIS results for the MS1 electrode after various cycles that are presented in Figure 7 d revealed a trend of reduction in the suppressed semicircle. Also, in Figure 7e, as the reversible cycling proceeded, the slope value gradually decreased. From these results, we can conclude that the charge transfer kinetics and lithium ion diffusion coefficient increased with increasing cycle number, which helped the electrode to deliver better electrochemical performance. To examine the structural stability of the electrodes, ex-situ XRD was conducted after various cycles, and the corresponding XRD patterns are exhibited in Figure 8a. Peaks of copper foil centered at about 43.5 ° and 50.4 ° were observed for all the patterns. The signal peaks of α-MnSe appeared at around 32.8 ° and 47.0 ° in the electrode before cycling. After 1 cycle, a phase transition phenomenon was detected in the XRD pattern (Figure 8a and 8b). The α phase was transformed to β phase, accompanied by a weak signal peak at 26.5 °. As the cycle number increased, there was no obvious phase transformation, but the peaks became weaker, demonstrating the high structural reversibility of β-MnSe and the gradual reduction in the size of manganese selenide particles. An HRTEM image of MS1 electrodes after 1 cycle was also


Page 18 of 35

Page 19 of 35 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


employed to demonstrate this. As shown in Figure 8c, the lattice has an interplanar spacing of 0.336 nm, which corresponds to the (111) crystal planes in the β-MnSe phase. The lattice spacing for (220) crystal planes in the β-MnSe phase was also recorded for the electrode after 200 cycles (Figure S4), further confirming the process of the phase transformation. The phase evolution during the cycling process is shown in the schematic illustration (Figure 8d). Apart from the structural transformation, the growth of metal selenide nanoparticles is effectively restricted by the pervasive carbon networks in the particle region, and the volume variation is also simultaneously restricted, resulting in structural integrity during the repeated cycling process. In addition, the carbon network also provides a stable conductive channel to achieve high electrochemical kinetics (Figure 8e). The synergy of these advantages is beneficial for acquiring high cycling reversibility and great rate performance. To better understand the influence of the phase transformation on the electrochemical performance, the diffusion energy barriers to a Li atom in β-MnSe and α-MnSe supercells were calculated by density functional theory (DFT) calculations. Top views of the supercell models for β-MnSe and α-MnSe are presented in Figure 9a, Figure S5a and Figure S6a, respectively, where the stable positions were in the selenium tetrahedral center or the manganese octahedral center 59. The diffusion energy barrier was determined by utilizing the climbing-image nudged elastic band (NEB) method. The energies from the NEB results as a function of the diffusion coordinates in β-MnSe and α-MnSe are presented in Figure 9b, Figure S5b and Figure S6b. As we can see, for β-MnSe, the Li atom only needs to surmount a low energy barrier (0.51 eV for stable



state or 0.52 eV for metastable state) in order to diffuse between two stable positions, while the diffusion energy barrier for α-MnSe was 0.72 eV. In addition, the electron localization function (ELF) was introduced to better interpret the electronic origin of the energy barrier to the diffusion of lithium atoms between two stable adsorption sites, which can be considered as a useful indicator for characterizing the bonding. The calculated ELF values of systems with Li atom diffusion in a β-MnSe supercell at the stable and saddle-point configurations, respectively, are displayed in Figure 9c and 9d. The ELF around the Li atom mainly reveals the same values for the two configurations, showing strong electron localization around the Li atom. The similar ELF values (close to equality) for the two configurations implies ionic bonding. Consequently, the sufficiently small energy difference between the two configurations guarantees smooth diffusion in the β-MnSe supercell for lithium atoms. Alternatively, in Figure S6b and S6c, the large energy difference for the two configurations is illustrated in the ELF values for α-MnSe, corresponding to low charge transfer kinetics. These results demonstrate the faster diffusion of lithium ions in β-MnSe than in α-MnSe. Conclusion In summary, we successfully designed the synthesis of three MnSe/C porous hierarchical architectures. Because of their unique structures, MnSe nanoparticles were homogeneously embedded in hierarchical carbon networks with high specific surface area and a certain amount of void space, providing fast lithium ion/electron transport, reduced aggregation, and great tolerance for volumetric changes as well as a large density of available active sites for lithium ion storage. The intrinsic pseudo-capacitive


Page 20 of 35

Page 21 of 35 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


behavior contributed a large portion of the total stored charge. In addition, the firstprinciples calculations demonstrated that there is a low energy barrier to diffusion during Li-ion intercalation in β-MnSe formed through an in-situ irreversible electrochemical phase transformation, guaranteeing good high-rate performance. Thus, when used as anode material for LIBs, the MnSe/C chestnut-like hybrids exhibited high specific capacity, excellent electrochemical capacity retention, and outstanding rate performance. Such well-designed hierarchical structures can be helpful for guiding the design of other metal selenides/carbon hybrids with superior electrochemical performance for a variety of applications, ranging from supercapacitors to electrocatalysis.

ASSOCIATED CONTENT Supporting Information XRD patterns, HRTEM images, FTIR results, Raman spectra, Nitrogen adsorptiondesorption isotherm, pore size distribution results, Potential-time curves and simulation results. This material is available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION Corresponding Authors (*): Prof. Yangai Liu: [email protected]; Prof. Rongkun Zheng: [email protected]; Prof. Zaiping Guo: [email protected]



Conflict of Interest The authors declare no conflict of interest.

ACKNOWLEDGEMENTS We acknowledge financial support from the Australian Research Council (DP150100018), the Fundamental Research Funds for the Central Universities (Grant No. 53200859035), the National Natural Science Foundation of China (Grant No. 51702289), and the China Postdoctoral Science Foundation (Grant No. 2016M601963). T. Yang would like to thank the China Scholarship Council for financial support. References and notes (1) Aricò, A. S.; Bruce, P.; Scrosati, B.; al., e. Nanostructured materials for advanced energy conversion and storage devices. Nat. Mater. 2005, 4 (5), 366-377. (2) Armand, M.; Tarascon, J.-M. Building better batteries. Nat. 2008, 451, 652-657. (3) Chen, T.; Hu, Y.; Cheng, B.; Chen, R.; Lv, H.; Ma, L.; Zhu, G.; Wang, Y.; Yan, C.; Tie, Z.; Jin, Z.; Liu, J. Multi-yolk-shell copper oxide@carbon octahedra as high-stability anodes for lithium-ion batteries. Nano Energy 2016, 20, 305-314, DOI: 10.1016/j.nanoen.2015.12.024. (4) Sun, Y.; Hu, X.; Luo, W.; Xia, F.; Huang, Y. Reconstruction of Conformal Nanoscale MnO on Graphene as a High-Capacity and Long-Life Anode Material for Lithium Ion Batteries. Adv. Funct. Mater. 2013, 23 (19), 2436-2444, DOI: 10.1002/adfm.201202623. (5) Liu, J.; Wu, C.; Xiao, D.; Kopold, P.; Gu, L.; van Aken, P. A.; Maier, J.; Yu, Y. MOF-Derived Hollow Co9S8 Nanoparticles Embedded in Graphitic Carbon Nanocages with Superior Li-Ion Storage. Small 2016, 12 (17), 2354-2364, DOI: 10.1002/smll.201503821. (6) Tong, H.; Xu, Y.; Cheng, X.; Zhang, X.; Gao, S.; Zhao, H.; Huo, L. One-pot solvothermal synthesis of hierarchical WO3 hollow microspheres with superior lithium ion battery anode performance. Electrochim. Acta 2016, 210, 147-154, DOI: 10.1016/j.electacta.2016.05.154. (7) Cai, P.; Huang, J.; Chen, J.; Wen, Z. Oxygen-Containing Amorphous Cobalt Sulfide Porous Nanocubes as High-Activity Electrocatalysts for the Oxygen Evolution Reaction in an Alkaline/Neutral Medium. Angew Chem. Int. Ed. Engl. 2017, 56 (17), 4858-4861, DOI: 10.1002/anie.201701280. (8) Li, W.; Li, H.; Lu, Z.; Gan, L.; Ke, L.; Zhai, T.; Zhou, H. Layered phosphorus-like GeP5: a promising anode candidate with high initial coulombic efficiency and large capacity for lithium ion batteries. Energy Environ. Sci. 2015, 8 (12), 3629-3636, DOI: 10.1039/c5ee02524a. (9) Deng, Z.; Jiang, H.; Hu, Y.; Liu, Y.; Zhang, L.; Liu, H.; Li, C. 3D Ordered Macroporous MoS2@C


Page 22 of 35

Page 23 of 35 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


Nanostructure for Flexible Li-Ion Batteries. Adv. Mater. 2017, 29 (10), 1603020, DOI: 10.1002/adma.201603020. (10) Xiao, Y.; Hwang, J. Y.; Sun, Y. K. Micro-Intertexture Carbon-Free Iron Sulfides as Advanced High Tap Density Anodes for Rechargeable Batteries. ACS Appl. Mater. Interfaces 2017, 9 (45), 39416-39424, DOI: 10.1021/acsami.7b13239. (11) Fang, Y.; Lv, Y.; Gong, F.; Elzatahry, A. A.; Zheng, G.; Zhao, D. Synthesis of 2D-MesoporousCarbon/MoS2 Heterostructures with Well-Defined Interfaces for High-Performance Lithium-Ion Batteries. Adv. Mater. 2016, 28 (42), 9385-9390, DOI: 10.1002/adma.201602210. (12) Teng, Y.; Zhao, H.; Zhang, Z.; Li, Z.; Xia, Q.; Zhang, Y.; Zhao, L.; Du, X.; Du, Z.; Lv, P.; Swierczek, K. MoS2 Nanosheets Vertically Grown on Graphene Sheets for Lithium-Ion Battery Anodes. ACS Nano 2016, 10 (9), 8526-8535, DOI: 10.1021/acsnano.6b03683. (13) Yuan, D.; Huang, G.; Yin, D.; Wang, X.; Wang, C.; Wang, L. Metal-Organic Framework Template Synthesis of NiCo2S4@C Encapsulated in Hollow Nitrogen-Doped Carbon Cubes with Enhanced Electrochemical Performance for Lithium Storage. ACS Appl. Mater. Interfaces 2017, 9 (21), 1817818186, DOI: 10.1021/acsami.7b02176. (14) Zhang, L.; Zuo, L.; Fan, W.; Liu, T. NiCo2S4 Nanosheets Grown on 3D Networks of Nitrogen-Doped Graphene/Carbon Nanotubes: Advanced Anode Materials for Lithium-Ion Batteries. ChemElectroChem 2016, 3 (9), 1384-1391, DOI: 10.1002/celc.201600183. (15) Xu, X.; Ji, S.; Gu, M.; Liu, J. In Situ Synthesis of MnS Hollow Microspheres on Reduced Graphene Oxide Sheets as High-Capacity and Long-Life Anodes for Li- and Na-Ion Batteries. ACS Appl. Mater. Interfaces 2015, 7 (37), 20957-20964, DOI: 10.1021/acsami.5b06590. (16) Liu, Y.; Qiao, Y.; Zhang, W.-X.; Li, Z.; Hu, X.-L.; Yuan, L.-X.; Huang, Y.-H. Coral-like α-MnS composites with N-doped carbon as anode materials for high-performance lithium-ion batteries. J. Mater. Chem. 2012, 22 (45), 24026-24033, DOI: 10.1039/c2jm35227c. (17) Li, N.; Zhang, Y.; Zhao, H.; Liu, Z.; Zhang, X.; Du, Y. Synthesis of High-Quality alpha-MnSe Nanostructures with Superior Lithium Storage Properties. Inorg. Chem. 2016, 55 (6), 2765-2770, DOI: 10.1021/acs.inorgchem.5b02558. (18) Ning, J.; Zhang, D.; Song, H.; Chen, X.; Zhou, J. Branched carbon-encapsulated MnS core/shell nanochains prepared via oriented attachment for lithium-ion storage. J. Mater. Chem. A 2016, 4 (31), 12098-12105, DOI: 10.1039/c6ta04441g. (19) Hao, Y.; Chen, C.; Yang, X.; Xiao, G.; Zou, B.; Yang, J.; Wang, C. Studies on intrinsic phase-dependent electrochemical properties of MnS nanocrystals as anodes for lithium-ion batteries. J. Power Sources 2017, 338, 9-16, DOI: 10.1016/j.jpowsour.2016.11.032. (20) Zhao, L.; Yu, X.; Yu, J.; Zhou, Y.; Ehrlich, S. N.; Hu, Y.-S.; Su, D.; Li, H.; Yang, X.-Q.; Chen, L. Remarkably Improved Electrode Performance of Bulk MnS by Forming a Solid Solution with FeS - Understanding the Li Storage Mechanism. Adv. Funct. Mater. 2014, 24 (35), 5557-5566, DOI: 10.1002/adfm.201400934. (21) Fei, L.; Williams, B. P.; Yoo, S. H.; Carlin, J. M.; Joo, Y. L. A general approach to fabricate freestanding metal sulfide@carbon nanofiber networks as lithium ion battery anodes. Chem. Commun. (Camb) 2016, 52 (7), 1501-1504, DOI: 10.1039/c5cc06957b. (22) Xue, M.; Fu, Z. Manganese selenide thin films as anode material for lithium-ion batteries. Solid State Ionics 2007, 178 (3-4), 273-279, DOI: 10.1016/j.ssi.2006.12.020. (23) Han, X.; Sun, L.; Wang, F.; Sun, D. MOF-derived honeycomb-like N-doped carbon structures assembled from mesoporous nanosheets with superior performance in lithium-ion batteries. J. Mater. Chem. A 2018, 6 (39), 18891-18897, DOI: 10.1039/c8ta07682k.



Page 24 of 35

(24) Wang, M. J.; Mao, Z. X.; Liu, L.; Peng, L.; Yang, N.; Deng, J.; Ding, W.; Li, J.; Wei, Z. Preparation of Hollow Nitrogen Doped Carbon via Stresses Induced Orientation Contraction. Small 2018, 1804183, DOI: 10.1002/smll.201804183. (25) Kale, V. S.; Hwang, M.; Chang, H.; Kang, J.; Chae, S. I.; Jeon, Y.; Yang, J.; Kim, J.; Ko, Y.-J.; Piao, Y.; Hyeon, T. Microporosity-Controlled Synthesis of Heteroatom Codoped Carbon Nanocages by WrapBake-Sublime Approach for Flexible All-Solid-State-Supercapacitors. Adv. Funct. Mater. 2018, 28 (37), 1803786, DOI: 10.1002/adfm.201803786. (26) Zhang, L.; Liu, W.; Shi, W.; Xu, X.; Mao, J.; Li, P.; Ye, C.; Yin, R.; Ye, S.; Liu, X.; Cao, X.; Gao, C. Boosting Lithium Storage Properties of MOF Derivatives through a Wet-Spinning Assembled Fiber Strategy. Chem. 2018, 24 (52), 13792-13799, DOI: 10.1002/chem.201802826. (27) Yang, T.; Liu, Y.; Huang, Z.; Liu, J.; Bian, P.; Ling, C. D.; Liu, H.; Wang, G.; Zheng, R. In situ growth of ZnO nanodots on carbon hierarchical hollow spheres as high-performance electrodes for lithium-ion batteries. J. Alloy Compd. 2018, 735, 1079-1087, DOI: 10.1016/j.jallcom.2017.11.125. (28) Tian, W.; Hu, H.; Wang, Y.; Li, P.; Liu, J.; Liu, J.; Wang, X.; Xu, X.; Li, Z.; Zhao, Q.; Ning, H.; Wu, W.; Wu, M. Metal-Organic Frameworks Mediated Synthesis of One-Dimensional MolybdenumBased/Carbon Composites for Enhanced Lithium Storage. ACS Nano 2018, 12 (2), 1990-2000, DOI: 10.1021/acsnano.7b09175. (29) Zhang, H.; Wang, Y.; Zhao, W.; Zou, M.; Chen, Y.; Yang, L.; Xu, L.; Wu, H.; Cao, A. MOF-Derived ZnO Nanoparticles Covered by N-Doped Carbon Layers and Hybridized on Carbon Nanotubes for LithiumIon

Battery

Anodes.

ACS

Appl.

Mater.

Interfaces

2017,

9

(43),

37813-37822,

DOI:

10.1021/acsami.7b12095. (30) Wu, R.; Wang, D. P.; Rui, X.; Liu, B.; Zhou, K.; Law, A. W.; Yan, Q.; Wei, J.; Chen, Z. In-situ formation of hollow hybrids composed of cobalt sulfides embedded within porous carbon polyhedra/carbon nanotubes for high-performance lithium-ion batteries. Adv. Mater. 2015, 27 (19), 3038-3044, DOI: 10.1002/adma.201500783. (31) Yang, T.; Yang, D.; Liu, Y.; Liu, J.; Chen, Y.; Bao, L.; Lu, X.; Xiong, Q.; Qin, H.; Ji, Z.; Ling, C. D.; Zheng, R. MOF-derived carbon-encapsulated cobalt sulfides orostachys-like micro/nano-structures as advanced anode material for lithium ion batteries. Electrochim. Acta 2018, 290, 193-202, DOI: 10.1016/j.electacta.2018.08.084. (32) Dai, R.; Sun, W.; Lv, L. P.; Wu, M.; Liu, H.; Wang, G.; Wang, Y. Bimetal-Organic-Framework Derivation of Ball-Cactus-Like Ni-Sn-P@C-CNT as Long-Cycle Anode for Lithium Ion Battery. Small 2017, 13 (27), 1700521, DOI: 10.1002/smll.201700521. (33) Li, G.; Yang, H.; Li, F.; Du, J.; Shi, W.; Cheng, P. Facile formation of a nanostructured NiP2@C material for advanced lithium-ion battery anode using adsorption property of metal–organic framework. J. Mater. Chem. A 2016, 4 (24), 9593-9599, DOI: 10.1039/c6ta02059c. (34) Fan, H.; Yu, H.; Wu, X.; Zhang, Y.; Luo, Z.; Wang, H.; Guo, Y.; Madhavi, S.; Yan, Q. Controllable Preparation of Square Nickel Chalcogenide (NiS and NiSe2) Nanoplates for Superior Li/Na Ion Storage Properties. ACS Appl. Mater. Interfaces 2016, 8 (38), 25261-25267, DOI: 10.1021/acsami.6b07300. (35) Zhang, Z.; Shi, X.; Yang, X. Synthesis of core-shell NiSe/C nanospheres as anodes for lithium and sodium storage. Electrochim. Acta 2016, 208, 238-243, DOI: 10.1016/j.electacta.2016.04.183. (36) Jin, J.; Zheng, Y.; Kong, L. B.; Srikanth, N.; Yan, Q.; Zhou, K. Tuning ZnSe/CoSe in MOF-derived Ndoped porous carbon/CNTs for high-performance lithium storage. J. Mater. Chem. A 2018, 6 (32), 15710-15717, DOI: 10.1039/c8ta04425b. (37) Li, Z.; Xue, H.; Wang, J.; Tang, Y.; Lee, C.-S.; Yang, S. Reduced Graphene Oxide/Marcasite-Type


Page 25 of 35 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


Cobalt Selenide Nanocrystals as an Anode for Lithium-Ion Batteries with Excellent Cyclic Performance. ChemElectroChem 2015, 2 (11), 1682-1686, DOI: 10.1002/celc.201500179. (38) Hu, H.; Zhang, J.; Guan, B.; Lou, X. W. Unusual Formation of CoSe@carbon Nanoboxes, which have an Inhomogeneous Shell, for Efficient Lithium Storage. Angew Chem. Int. Ed. Engl. 2016, 55 (33), 95149518, DOI: 10.1002/anie.201603852. (39) Kresse, G.; Furthmuller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B: Condens. Matter Mater. Phys. 1996, 54, 11169-11186. (40) Kresse, G.; Furthmuller, J. Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput. Mater. Sci. 1996, 6, 15-50. (41) Kresse, G.; Joubert, D. From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 1999, 59, 1758-1775. (42) Blöchl, P. E. Projector augmented-wave method. Phys. Rev. B 1994, 50 (24), 17953-17979, DOI: 10.1103/PhysRevB.50.17953. (43) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 1996 (77), 3865-3868. (44) Monkhorst, H. J.; Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B: Condens. Matter Mater. Phys. 1976, 13 (12), 5188-5192, DOI: 10.1103/PhysRevB.13.5188. (45) Henkelman, G.; Uberuaga, B. P.; J´ onsson, H. A climbing image nudged elastic band method for finding saddle points and minimum energy paths. J. Chem. Phys. 2000, 113, 9901-9904, DOI: 10.1063/1.4878664. (46) Liu, W. W.; Wang, D.; Wang, Z.; Deng, J.; Lau, W. M.; Zhang, Y. Influence of magnetic ordering and Jahn-Teller distortion on the lithiation process of LiMn2O4. Phys. Chem. Chem. Phys. 2017, 19 (9), 64816486, DOI: 10.1039/c6cp08324b. (47) Wang, L.; Maxisch, T.; Ceder, G. A First-Principles Approach to Studying the Thermal Stability of Oxide Cathode Materials. Chem. Mater. 2007, 19 (3), 543-552, DOI: 10.1021/cm0620943. (48) Yang, T.; Liu, Y.; Yang, D.; Deng, B.; Huang, Z.; Ling, C. D.; Liu, H.; Wang, G.; Guo, Z.; Zheng, R. Bimetallic metal-organic frameworks derived Ni-Co-Se@C hierarchical bundle-like nanostructures with high-rate pseudocapacitive lithium ion storage. Energy Storage Mater. 2018, 17, 374-384, DOI: 10.1016/j.ensm.2018.05.024. (49) Qi, Y.; Liu, B.; Zhang, L.; Huo, Y.; Li, L.; Xie, H.; Wang, C.; Su, Z. One-pot controllable synthesis of CoFe2O4 solid, hollow and multi-shell hollow nanospheres as superior anode materials for lithium ion batteries. J. Mater. Chem. A 2017, 5 (41), 21994-22003, DOI: 10.1039/c7ta07272d. (50) Xie, Q.; Zeng, D.; Gong, P.; Huang, J.; Ma, Y.; Wang, L.; Peng, D.-L. One-pot fabrication of graphene sheets decorated Co2P-Co hollow nanospheres for advanced lithium ion battery anodes. Electrochim. Acta 2017, 232, 465-473, DOI: 10.1016/j.electacta.2017.03.003. (51) Xiao, Y.; Zheng, L.; Cao, M. Hybridization and pore engineering for achieving high-performance lithium storage of carbide as anode material. Nano Energy 2015, 12, 152-160, DOI: 10.1016/j.nanoen.2014.12.015. (52) Hu, Y. Y.; Liu, Z.; Nam, K. W.; Borkiewicz, O. J.; Cheng, J.; Hua, X.; Dunstan, M. T.; Yu, X.; Wiaderek, K. M.; Du, L. S.; Chapman, K. W.; Chupas, P. J.; Yang, X. Q.; Grey, C. P. Origin of additional capacities in metal oxide lithium-ion battery electrodes. Nat. Mater. 2013, 12 (12), 1130-1136, DOI: 10.1038/nmat3784. (53) Cook, J. B.; Kim, H.-S.; Yan, Y.; Ko, J. S.; Robbennolt, S.; Dunn, B.; Tolbert, S. H. Mesoporous MoS2 as a Transition Metal Dichalcogenide Exhibiting Pseudocapacitive Li and Na-Ion Charge Storage. Adv.



Page 26 of 35

Energy Mater. 2016, 6 (9), 1501937, DOI: 10.1002/aenm.201501937. (54) Muller, G. A.; Cook, J. B.; Kim, H. S.; Tolbert, S. H.; Dunn, B. High performance pseudocapacitor based on 2D layered metal chalcogenide nanocrystals. Nano Lett. 2015, 15 (3), 1911-1917, DOI: 10.1021/nl504764m. (55) Zhou, Y.; Yan, D.; Xu, H.; Feng, J.; Jiang, X.; Yue, J.; Yang, J.; Qian, Y. Hollow nanospheres of mesoporous Co9S8 as a high-capacity and long-life anode for advanced lithium ion batteries. Nano Energy 2015, 12, 528-537, DOI: 10.1016/j.nanoen.2015.01.019. (56) Xiang, Y.; Yang, Z.; Wang, S.; Hossain, M. S. A.; Yu, J.; Kumar, N. A.; Yamauchi, Y. Pseudocapacitive behavior of the Fe2O3 anode and its contribution to high reversible capacity in lithium ion batteries. Nanoscale 2018, 10 (37), 18010-18018, DOI: 10.1039/c8nr04871a. (57) Yao, Y.; Zhu, Y.; Huang, J.; Shen, J.; Li, C. Porous CoS nanosheets coated by N and S doped carbon shell on graphene foams for free-standing and flexible lithium ion battery anodes: Influence of void spaces,

shell

and

porous

nanosheet.

Electrochim.

Acta

2018,

271,

242-251,

DOI:

10.1016/j.electacta.2018.03.144. (58) Wang, P.; Zhang, Y.; Yin, Y.; Fan, L.; Zhang, N.; Sun, K. In Situ Synthesis of CuCo2S4@N/S-Doped Graphene Composites with Pseudocapacitive Properties for High-Performance Lithium-Ion Batteries. ACS Appl. Mater. Interfaces 2018, 10 (14), 11708-11714, DOI: 10.1021/acsami.8b00632. (59) Zhong, K.; Hu, R.; Xu, G.; Yang, Y.; Zhang, J.-M.; Huang, Z. Adsorption and ultrafast diffusion of lithium in bilayer graphene: Ab initio and kinetic Monte Carlo simulation study. Phys. Rev. B 2019, 99 (15), 155403, DOI: 10.1103/PhysRevB.99.155403.

Figures and Tables

Figure 1. Schematic illustration of the synthesis strategy for the hierarchical αMnSe/C structures.


Page 27 of 35 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 2 Low-magnification and high-magnification SEM images of typical morphology for MBTC1 (a-c), MBTC2 (d-f), and MBTC3 (g-i).



Figure 3 Low-magnification and high-magnification SEM images of typical morphology for MS1 (a-c), MS2 (d-f), and MS3 (g-i) after in-situ selenization.


Page 28 of 35

Page 29 of 35 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 4. (a, b) TEM and (c) HRTEM images, and (d) the corresponding elemental EDS mapping images of MS1.



Figure 5 (a) CV curves for the first 5 cycles recorded at a scan rate of 0.1 mV·s−1 between 0.01 and 3.0 V vs. Li/Li+, and (b) galvanostatic charge-discharge curves of MS1 electrode; (c) Cycling performances of the samples at the current density of 0.2 A g−1, (d) rate performance at various current densities from 0.1 to 2 A·g−1, and (e) long-term cycling performances at a current density of 1 A·g−1 of MS1, MS2 and MS3 electrodes.


Page 30 of 35

Page 31 of 35 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 6. (a) CV curves at various scan rates and (b) the corresponding log(i) vs. log(v) plots at specific peak currents for MS1 electrodes; (c) CV curves at various scan rates and (d) the corresponding log(i) vs. log(v) plots at specific peak currents for MS2 electrodes; (e) CV curves at various scan rates, and (f) the corresponding log(i) vs. log(v) plots at specific peak currents for MS3 electrodes.



Figure 7 (a) GITT curves and the corresponding Li+ diffusion coefficients at different


Page 32 of 35

Page 33 of 35 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


lithiation/delithiation states for the three electrodes. (b) EIS spectra and (c) the corresponding relationship plots of Z’ vs. ω−1/2 in the low-frequency region for the three electrodes after 60 cycles, recorded at open circuit potential; (d) EIS spectra and (e) the corresponding relationship plots of Z’ vs. ω−1/2 in the low-frequency region for the MS1 electrodes after various cycles.

Figure 8 (a) Ex situ XRD patterns and (b) narrow-angle XRD patterns of MS1 electrodes after various cycles; (c) HRTEM image of MS1 electrode after the initial cycle; (d) crystal structure, and (e) composition and morphology change during repeated lithiation/delithiation processes in the electrodes.



Figure 9 Density-functional theory (DFT) simulations for β-MnSe in stable state. (a) Top view of β-MnSe supercell. (b) The energies of nudged elastic band (NEB) images as functions of the diffusion coordinates in β-MnSe supercells. (c) The electron localization function (ELF) for the stable configurations. (d) The electron localization function (ELF) for the saddle configurations.


Page 34 of 35

Page 35 of 35 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



Encapsulating MnSe nanoparticles inside 3D hierarchical carbon

Recommend Documents