1D Tunnels Research Articles

Open frameworks in the NaxMny(P2O7)mFn fluoro-pyrophosphates system.

Three new sodium manganese fluoro-pyrophosphate compounds, namely, Na5.5Mn1.5(P2O7)2F0.5 (I), Na7Mn0.75(P2O7)2F2 (II), and Na9Mn3(P2O7)4F (III), have been synthesized by heating a mixture of NaPF6, Na2PO3F or NaH2PO4 with different Mn sources in NaNO3 and KNO3 fluxes. The structures of the title compounds were characterized via single-crystal X-ray diffraction (XRD). II is characteristic of a shell of Na+ ions that encloses one [Mn0.75(P2O7)2F2]7- unit, whereas I and III reveal three-dimensional (3D) frameworks that consist of MnO6, Mn/NaO5F0.5 octahedra or MnO6 octahedra and distorted MnO5 square pyramids with P2O7 units, where Na+ cations reside in different-membered ring one-dimensional (1D) tunnels. The estimated total Na+ ion conductivity for a pellet of III in open air is 10-5 S cm-1 at 400 °C, which is lower than that of many NASICON-type compounds at room temperature, with a higher activation energy of 0.89 eV for III compared to the value of ∼0.4 eV for high-performance sodium ion conductors. The analysis of Na+ diffusion pathways revealed that percolation occurs through a zig-zag chain along the b axis via the bond valence energy landscape approach. Detailed characterization, such as spectroscopic and magnetic properties and specific heat for III, is also reported.

C3H7N6]3[B3O5(OH)2] and [C3H8N6]4[B12O19(OH)6]: Two Melamine Borates with Large Birefringence.

The π-conjugated [C3H6+xN6]x+ (x = 0-3) cations are good functional groups, which are widely employed in the preparations of nonlinear optical (NLO) and birefringent materials due to their high hyperpolarizability and optical anisotropy. In this paper, the first melamine hydroxyborate [C3H7N6]3[B3O5(OH)2] (MelBO-I) was synthesized by the boric acid melting method under the molar ratio of H3BO3:C3H6N6 = 1:1. MelBO-I (P21/c) exhibits a two-dimensional (2D) {[C3H7N6]3[B3O5(OH)2]}∞ layer composed of [C3H7N6]+ cations and [B3O5(OH)2]3- anions interconnected via hydrogen bonds. MelBO-I exhibits significant birefringence (Δn = 0.286@546 nm). Under the molar ratio of H3BO3/C3H6N6 = 3:1, [C3H8N6]4[B12O19(OH)6] (MelBO-II) was isolated. In MelBO-II (P21), highly polymerized [B12O19(OH)6]8- groups form a 3D network through hydrogen bonding, featuring 1D tunnels of 8-membered and 16-membered rings filled by [C3H8N6]2+ cations. MelBO-II is the first noncentrosymmetric (NCS) bifunctional melamine borate with a moderate SHG response (0.4 × KDP) and large birefringence (Δn = 0.285@546 nm). The results indicate that incorporating [C3H6+xN6]x+ (x = 0-3) cations into borate can effectively induce birefringence. A high concentration of boric acid promotes the formation of large boric acid cluster anions and facilitates the transformation from the CS to NCS structure.

Vibration response of piles at different distances induced by shield tunneling in hard rock strata

Excavation of subway tunnels in hard rock generates strong vibration waves that pose potential risks to the stability of surrounding structures. In this study, the discrete element method-finite difference method (DEM-FDM) coupling was adopted to build the model of tunnel structure-rock-pile, which was validated by field monitoring data. Then, the vibration response of piles under various pile-tunnel spacings was analyzed, revealing the occurrence of vibration peak rebound phenomena within certain distance ranges. The range of vibration effects was categorized. Furthermore, in shield tunneling construction, the energy induced by vibrations was mainly concentrated within the 50 Hz range. Low-frequency vibrations result in a wider effect range. The study also demonstrated that within a 1d (tunnel diameter) range of the pile-tunnel spacing, the vibration induced by shield tunneling construction had a more significant effect. As the pile-tunnel spacing increased, the piles transitioned from being subjected to bending forces to experiencing bending-shear forces. Finally, the vibration effects on the existing piles were evaluated under field working conditions. It also provided suggestions for construction based on the effects and laws of the pile dynamic response.

Asymmetric 1D and 2D tunneling induced grating in Quantum Dot system

We propose a tunneling-induced grating based on the phenomenon of tunneling-induced transparency. Our method allows us to alternate between zeroth-order diffraction along with completely different higher-order diffraction patterns. This is accomplished by using four laser beams to drive quantum dots via a planar configuration. Specifically, we modulate a standing waves controlling beam which propagates orthogonal with the planar medium, while weaker planar probing beam, generated signal field, and pumping field are applied adjacent towards the medium. We quantitatively analyzed the dynamics for the phase, amplitude modulations, along with probing fields diffraction strengths of various ordering. By altering the relative phase of fields, we expect asymmetric 1D and 2D tunneling induced grating in quantum dot system. Our suggested approach has significant uses in optical memory systems, notably in the storing of information to diffraction orders via tunneling-induced grating.

Regulated electrochemical performance of manganese oxide cathode for potassium-ion batteries: A combined experimental and first-principles density functional theory (DFT) investigation

Potassium-ion batteries (KIBs) are promising energy storage devices owing to their low cost, environmental-friendly, and excellent K+ diffusion properties as a consequence of the small Stoke's radius. The evaluation of cathode materials for KIBs, which are perhaps the most favorable substitutes to lithium-ion batteries, is of exceptional importance. Manganese dioxide (α-MnO2) is distinguished by its tunnel structures and plenty of electroactive sites, which can host cations without causing fundamental structural breakdown. As a result of the satisfactory redox kinetics and diffusion pathways of K+ in the structure, α-MnO2 nanorods cathode prepared through hydrothermal method, reversibly stores K+ at a fast rate with a high capacity and stability. It has a first discharge capacity of 142 mAh/g at C/20, excellent rate execution up to 5C, and a long cycling performance with a demonstration of moderate capacity retention up to 100 cycles. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) simulations confirm that the K+ intercalation/deintercalation occurs through 0.46 K movement between MnIV/MnIII redox pairs. First-principles density functional theory (DFT) calculations predict a diffusion barrier of 0.31 eV for K+ through the 1D tunnel of α-MnO2 electrode, which is low enough to promote faster electrochemical kinetics. The nanorod structure of α-MnO2 facilitates electron conductive connection and provides a strong electrode–electrolyte interface for the cathode, resulting in a very consistent and prevalent execution cathode material for KIBs.

Ba6Zn6(B3O6)6(B6O12): Barium Zinc Borate Contains π-Conjugated [B3O6]3- Anions and [B6O12]6- Anion with Edge-Sharing BO4 Tetrahedra.

A novel barium zinc borate contains π-conjugated [B3O6]3- anions and [B6O12]6- anion with edge-sharing BO4 tetrahedra, Ba6Zn6(B3O6)6(B6O12), has been successfully synthesized via a high-temperature solution reaction. In its structure, the isolated planar π-conjugated B3O6 groups are interconnected by ZnO4 tetrahedra via corner sharing to construct a [Zn3(B3O6)3]3- single layer parallel to the ab plane with the large Zn3B6 9-member rings. Two adjacent [Zn3(B3O6)3]3- single layers are interconnected by [B6O12]6- anions into a two-dimensional [Zn6(B3O6)6(B6O12)]12- double layer with 1D tunnels of Zn4B8 12-member rings along the a-axis. Neighboring such double layers are packed in an A-B-A-B... fashion along the c axis, and the Ba2+ ions act as counterbalance cations filling in the voids of double layers. All of the planar π-conjugated [B3O6]3- groups in Ba6Zn6(B3O6)6(B6O12) are in approximately parallel arrangement, producing large optical anisotropy and birefringence. The UV-vis-NIR absorption spectrum manifests that the UV cutoff edge for the title compound is below 200 nm. Ba6Zn6(B3O6)6(B6O12) possesses the largest birefringence (0.115@1064 nm) among the zincoborates reported. Its thermal stability, infrared spectrum, and theoretical calculations were also performed.

Tunnel Structure Enhanced Polysulfide Conversion for Inhibiting "Shuttle Effect" in Lithium-Sulfur Battery.

The Lithium sulfur (Li-S) battery has a great potential to replace lithium-ion batteries due to its high-energy density. However, the “shuttle effect” of polysulfide intermediates (Li2S8, Li2S6, Li2S4, etc.) from the cathode can lead to rapid capacity decay and low coulombic efficiency, thus limiting its further development. Anchoring polysulfide and inhibiting polysulfide migration in electrolytes is one of the focuses in Li-S battery. It is well known that polar metal oxides-manganese oxides (MnO2) are normally used as an effective inhibitor for its polysulfide inhibiting properties. Considering the natural 1D tunnel structure, MnO2 with three kinds of typical tunnel-type were screened to study the effects of the tunnel size on the adsorption capacity of polysulfide. We found that MnO2 with larger tunnel sizes has stronger chemisorption capacity of polysulfide. It promotes the conversion of polysulfide, and corresponding cathode exhibits better cycle reliability and rate performance in the cell comparison tests. This work should point out a new strategy for the cathode design of advanced Li-S battery by controlling the tunnel size.

Vertically-oriented zinc-doped γ-MnO2 nanowalls as high-rate anode materials for li-ion batteries

Micro lithium-ion batteries (micro-LIBs), featuring small size, lightweight, high capacity, and long cycle life, are considered as promising on-chip micropower sources for a wide variety of miniaturized electronics. Three-dimensional (3D) self-supported anode nanoarchitectures are key to developing high-performance micro-LIBs. Manganese dioxide (MnO2) based rechargeable batteries, with high energy and power density, have received a great deal of attention as a potential alternative to the current battery systems. However, MnO2, with poor electrical conductivity and large volume change, always suffers from insufficient rate capability and inferior cycling stability during Li+ ion insertion/extraction, causing limited commercial applications. Herein, we report a facile one-step electrochemical deposition process for directly growing Zn-doped γ-MnO2 nanowalls (Zn/γ-MnO2 pNW) with inter-networked vertically-oriented 3D porous frameworks onto Ni foam, that results in a superior performance binder-free anode material for micro-LIBs. The 3D porous Zn-doped γ-MnO2 nanowalls exhibit an ultrahigh reversible capacity of ~2579.4 mAh g−1 at 0.1 A g−1. Importantly, the combined advantages of 3D porous nanowall architecture, 1D tunnels in γ-MnO2 crystalline, and zinc doping in MnO2, exhibit tremendous benefits for rate capability, owing to minimization of the electronic and ionic resistance as well as the decrease for ionic diffusion paths, reaching 828.5 mAh g−1 at 20 A g−1. Even at high current density of up to 50 A g−1, the electrode still delivers a capacity of 127.0 mAh g−1 after 5000 cycles. When cycled at 5 A g−1, a reversible capacity of 1545.4 mAh g−1 with a capacity retention of 92.2 % is obtained after 1500 cycles. With a simple synthetic process and desirable electrochemical performance, the Zn/γ-MnO2 pNW may present a promising opportunity for large-scale miniature power sources with high-power properties.

Empty Valence‐Band Pocket in p‐Type Cu2O(111) Probed with Scanning Tunneling Spectroscopy

Scanning tunneling spectroscopy is used to probe the surface electronic structure of (√3×√3)‐reconstructed cuprous oxide films on Au(111). In analogy to bulk Cu2O(111), the films show a pronounced p‐type nature with the valence‐band top pinned to the Fermi level and the conduction‐band onset located at +2.0 V. A conductance dip appears directly at zero bias in the dI/dV spectra, followed by an asymmetric dI/dV maximum inside the lower half of the bandgap. Several scenarios are considered to explain this unusual conductance behavior. The most likely interpretation is based on the accumulation of hole states in the p‐type material in response to the tip‐electric field and the development of an empty valence‐band pocket directly below the tip. Tunneling into these states leads to a finite dI/dV intensity even inside the Cu2O bandgap. A 1D tunneling model that accounts for this field‐dependent transport mechanism successfully reproduces the experimental data and rationalizes the impact of current setpoint, oxide thickness, and surface reconstruction on the observed spectral response.

Low temperature treatment and structural characterization of Na 2M2Fe(PO4)3 (M= Mn or Ni) Alluaudite phases

Materials for sodium intercalation were recently considered as attractive potential cathode materials for Na-ion Batteries. Amongst others, Alluaudite phases have shown interesting electrochemical properties. Thanks to their structure which consists of a three-dimensional framework of octahedra and tetrahedra sharing corners and/or edges, giving rise to two types of 1D tunnels where the Na+ ions can be intercalated. As first attempt to optimize the electrochemical performances of two alluadiates phases used as cathode materials, namely, Na2Mn2Fe(PO4)3 and Na2Ni2Fe(PO4)3, we have prepared these compounds by co-precipitation method with controlled nanometric size and low calcination temperature of 700°C and 750°C respectively. The structure of both samples obtained at different calcination temperatures were investigated using powder X-ray diffraction. The experimental results show the purity of Na2Mn2Fe(PO4)3 and Na2Ni2Fe(PO4)3 phases as well as the high crystallinity while maintaining low particle size and low calcination temperatures, namely less than 100 - 150°C difference.

A new series of rare-earth borate-phosphate family CsNa2Ln2(BO3)(PO4)2 (Ln = Ho, Er, Tm, Yb): Tunnel structure, upconversion luminescence and optical thermometry properties

Developing new oxysalt compounds is always meaningful topic for their low cost and potential applications as laser crystal, piezoelectric crystal, frequency doubling crystal, magnet material and luminescent material. For the first time, this work prepared 1/10 millimeter-level single crystals of borate-phosphates CsNa2Ln2(BO3)(PO4)2 (Ln = Ho, Er, Tm, Yb) by using high temperature flux method with superfluous Cs2O‒NaF‒B2O3‒P2O5 constituents as flux and Ln2O3 as solute. Single crystal X-ray diffraction (SC-XRD) reveals that their structure features a 3D open framework of [Yb2(BO3)(PO4)2]∞ structure that delimiting 1D tunnels filling with [Na]∞ and [Cs]∞ chains. By taking CsNa2Yb2(BO3)(PO4)2 as host matrix and Er3+ as activator, upconversion (UC) phosphor CsNa2Yb2−xErx(BO3)(PO4)2 (x = 0.01–0.10) can be obtained. Excited by 980 nm pumping laser, it can emanate three characteristic bands of Er3+ at 522, 557 and 659 nm. Moreover, optical thermometry by the relative intensity of 522(2H11/2→4I15/2)/557(4S3/2→4I15/2) were investigated at temperatures from 303 to 573 K. The maximum relative sensitivity was measured to be 0.011 K−1 at 303 K, suggestion that CsNa2Yb2−xErx(BO3)(PO4)2 could be a promising candidate for optical thermometry.

Tunneling Spectroscopy of Quantum Spin Liquids.

We examine the spectroscopic signatures of tunneling through a Kitaev quantum spin liquid (QSL) barrier in a number of experimentally relevant geometries. We combine contributions from elastic and inelastic tunneling processes and find that spin-flip scattering at the itinerant spinon modes gives rise to a gapped contribution to the tunneling conductance spectrum. We address the spectral modifications that arise in a magnetic field, which is applied to drive the candidate material α-RuCl_{3} into a QSL phase, and we propose a lateral 1D tunnel junction as a viable setup in this regime. The characteristic spin gap is an unambiguous signature of the fractionalized QSL excitations, distinguishing it from magnons or phonons. We discuss the generalization of our results to a wide variety of QSLs with gapped and gapless spin correlators.

N, S Co‐Doped Porous Carbon from Antibiotic Bacteria Residues Enables a High‐Performance FeF3 ⋅ 0.33H2O Cathode for Li‐Ion Batteries

AbstractFeF3 ⋅ 0.33H2O is considered as a potential candidate cathode material owing to the special structure with one‐dimension (1D) tunnel. However, its practical application is hindered by the poor electric conductivity. In this work, FeF3 ⋅ 0.33H2O embedded into N, S co‐doped porous carbon (NSPC) derived from antibiotic bacterial residues was synthesized by a facile wet‐impregnation method. Close contact of FeF3 ⋅ 0.33H2O nanoparticles with NSPC can provide the rapid electron conduction channel and keep the structural stability, which endows that FeF3 ⋅ 0.33H2O@NSPC electrode achieves excellent cycling performance with a reversible capacity of 164.5 mAh g−1 at 40 mA g−1 after 100 cycles between 2.0 and 4.5 V and good rate performance. This study offers a new method for high‐value utilization of antibiotic bacteria residues (ABRs) for application in energy storage.

Flexible ligands-dependent formation of a new column layered MOF possess 1D channel and effective separation performance for CO2

A new column layered MOF with (3,6)-connected nets, namely [Co(pysa)(H2O)]n (YAU-7), was synthesized by using Co(NO3)2·6H2O and organic ligand 2-(pyrid-4′-yl)-benzimidazole-5-carboxylic acid (H2pysa) as flexible linkers. Single-crystal X-ray diffraction evidences the 3D YAU-7 MOF with (3,6)-connected nodes, a binuclear cluster [Co2(COO)2] structure and 1D tunnel feature. The weak interactions of π---π stacking enhances chemical stability of YAU-7 3D structure. Interestingly, the YAU-7 presents high chemical/thermodynamic stability, superior adsorption performance for CO2, CH4, C2H2 and C2H4, and high IAST selectivities for mixed gas systems of C2H2/CO2, C2H4/CO2, and CH4/CO2 (50/50). In contrast, YAU-7 exhibits higher uptake of CO2 (55.70 ​cm3 ​g−1) compared with CH4, C2H2, and C2H4 (27.39, 23.36, and 9.04 ​cm3 ​g−1) at 273 ​K. YAU-7 takes separation values for C2H2/CO2, C2H4/CO2, and CH4/CO2 mixture (37.6, 22.7, and 31.2) significantly higher than the C2H2/C2H4, C2H2/CH4, C2H2/CO2, C2H4/CH4 mixture gas (1.30, 1.83, 1.67). The YAU-7 MOF is a promising material for CO2 separation under ambient conditions.

Improving precision in regional scale numerical simulations of groundwater flow into underground openings

Dewatering is a common engineering practice to secure the accessibility during the construction and operational phases of tunnels. It is thus important to accurately estimate the amount of groundwater flow into underground openings for the design and safe operation of tunnels. Numerical models need to be used to estimate groundwater flow into openings for given heterogeneity and regional hydrologic boundary conditions typically by assuming that the atmospheric pressure is maintained along open wall faces. As the scale of openings can be small as tens of centimeters, while models need to incorporate the regional hydrologic conditions, it is often practically impossible to explicitly represent the three-dimensional (3D) geometry of openings within numerical models. For the safety assessment of deep geological repositories of spent nuclear fuels, for example, complex configurations and geometry of various tunnels such as construction, access, ventilation, and deposition tunnels often need to be approximated as one-dimensional (1D) lines in 3D models. The application of a simple Dirichlet boundary condition along a set of tunnel nodes may yield inaccurate solutions due to geometric simplifications and coarse discretization. This study derives an appropriate boundary condition that can be applied to 1D tunnel segments to improve the accuracy when simulating inflow into openings. A third-type tunnel boundary condition is suggested to correct the difference between known wall pressure and the pressure simulated at tunnel nodes. Improvement in the precision of the solutions is demonstrated by comparing the numerical solutions using the new boundary condition with analytic solutions, and with numerical solutions when the 3D tunnel geometry is explicitly simulated. It is also shown that the formulation can be easily extended to incorporate the high permeability excavation damaged zone and the low permeability grouted zone in the tunnel vicinity. The applicability of the tunnel boundary condition is demonstrated using an example of a hypothetical deep geologic repository system consisting of various types of tunnels located in a hypothetical crystalline coastal aquifer.

Targeted synthesis and reaction mechanism discussion of Mo2C based insertion-type electrodes for advanced pseudocapacitors

Zigzag 1D tunnel structure and high electronic conductivity power high performance of Mo2C based pseudocapacitive electrode.

A Two Dimensional Tunneling Resistance Transmission Line Model for Nanoscale Parallel Electrical Contacts

Contact resistance and current crowding are important to nanoscale electrical contacts. In this paper, we present a self-consistent model to characterize partially overlapped parallel contacts with varying specific contact resistivity along the contact length. For parallel tunneling contacts formed between contacting members separated by a thin insulating gap, we examine the local voltage-dependent variation of potential barrier height and tunneling current along the contact length, by solving the lumped circuit transmission line model (TLM) equations coupled with the tunneling current self consistently. The current and voltage distribution along the parallel tunneling contacts and their overall contact resistance are analyzed in detail, for various input voltage, electrical contact dimension, and material properties (i.e. work function, sheet resistance of the contact members, and permittivity of the insulating layer). It is found the existing one-dimensional (1D) tunneling junction models become less reliable when the tunneling layer thickness becomes smaller or the applied voltage becomes larger. In these regimes, the proposed self-consistent model may provide a more accurate evaluation of the parallel tunneling contacts. For the special case of constant ohmic specific contact resistivity along the contact length, our theory has been spot-checked with finite element method (FEM) based numerical simulations. This work provides insights on the design, and potential engineering, of nanoscale electrical contacts with controlled current distribution and contact resistance via engineered spatially varying contact layer properties and geometry.

The Effects of Tunnel and Layer Openings in Energetic Aqueous Zinc Ion Storage in Manganese Dioxides

Manganese dioxides (MnO2s) exhibit rich and diverse crystallographic structures (polymorphs). MnO2 polymorphs comprise one-dimensional (1D) tunnels and two-dimensional (2D) layers which allow fast and highly reversible ion-exchange properties. MnO2s have widely been studied as cathodes in aqueous rechargeable batteries due to their large tunnel and layer openings and reversible 3+/4+ Mn redox couple. Here, we are reporting high temperature (240oC) hydrothermal syntheses of two tunnel-structured MnO2s with 0.46 nm x 0.46 nm and 0.46 nm x 0.92 nm dimensions and a layered MnO2 with an interlayer spacing of 0.46 nm. MnO2 materials are fully characterized using PXRD, SEM/EDX, TEM, and N2-sorption. Synthesized MnO2 materials are tested as cathodes in rechargeable zinc ion batteries (ZIB) in two electrode cells and using Zn metal anode. Cyclic voltammetry, rate capability, and galvanostatic cycling performances are evaluated in two different aqueous Zn2+ electrolytes (ZnSO4 and ZnTFSI) to disclose the mechanistic changes of reversible Zn2+ storage and the relationship between storage, tunnel and layer dimensions, and electrolyte. During the CV tests, all three materials showed similar redox potentials in ZnSO4, whereas in ZnTFSI, layered and 0.46 nm x 0.92nm tunnel sized MnO2s showed significantly different redox potentials along with an additional oxidation peak. These MnO2s also showed better capacity retention in ZnTFSI than in ZnSO4. These MnO2 materials have similar crystallite sizes and surface areas (25-55 m2/g), differing only in the dimensions of their openings (layer or tunnel sizes). This allows us to directly evaluate the effect of the structural openings and electrolyte in functional electrochemistry by minimizing the effects of other physicochemical properties.

Highly efficient catalytic combustion of o-dichlorobenzene over lattice-distorted Ru/OMS-2: The rapidly replenishing effect of surface adsorbed oxygen on lattice oxygen

Cryptomelane-type catalysts (OMS-2) are known as their highly active lattice oxygen and unique structure with isolated K+ in open one dimensional (1D) tunnel. According to Mars van Krevelen (MVK) mechanism, the supplement of lattice oxygen by surface adsorbed oxygen is the critical step in catalytic oxidation reaction. Many researchers unilaterally tried to promote surface adsorbed oxygen or lattice oxygen reactivity to enhance OMS-2 catalytic performance. In this work, a more direct strategy was explored to improve the replenishing effect of surface adsorbed oxygen on lattice oxygen. Through etching OMS-2 nanorod with different crystallinity by weakly acidic RuCl3 solution, lattice-distorted Ru/OMS-2 catalysts were prepared which have abundant surface defects, lower Mn-O force constant, plentiful surface adsorbed oxygen and enhanced redox ability. Electronegative surface oxygen species (such as O2− and O−) were enriched by the adsorption of surface isolated Mn4+ ions which were supplement of K+ vacancies to balance charge. The greatly enhanced catalytic activity of OMS-2 on o-dichlorobenzene (o-DCB) combustion could be attributed to stable structure, excellent redox ability promoted by RuO2 and rapidly replenishing effect of surface adsorbed oxygen on lattice oxygen.

Top-down synthesis of iron fluoride/reduced graphene nanocomposite for high performance lithium-ion battery

To fabricate reliable conducting matrix for highly insulated iron fluoride, we design a facile, green and low-cost solvothermal based synthesis method using graphene oxide powders and commercial FeF3·3H2O as precursors for the preparation of FeF3·0.33H2O/reduced graphene oxide (denoted as FeF3·0.33H2O/rGO) nanocomposite, as it is achieved by a combination of self-assembly, top-down phase transformation and solvothermal reduction processes. The 1D tunnel structure of FeF3·0.33H2O phase, nanoscale size and graphene conductive matrix together ensure ultrafast Li ion and electron transport. When applied as a cathode in lithium-ion batteries, the FeF3·0.33H2O/rGO electrode displays durable long-term cyclability (98% capacity retention over 100 cycles at 0.5C) and impressive rate capability (122 mAh g−1 at 10C), wherein surface-induced capacitive process plays an important role. Meanwhile, we also demonstrate the successful preparation of FeF2/reduced graphene oxide (denoted as FeF2/rGO) nanocomposite through adaption of reaction temperature, which has been seldom synthesized and here also exhibits high electroactivity.