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Doping engineering has been recognized as an effective strategy for improving the solar‐to‐hydrogen conversion efficiency of delafossite CuFeO2‐based photocatalysts. However, a comprehensive and systematic study on the doping effect in CuFeO2 is still needed to establish a universal law. To address this, we utilized density functional theory calculations to scrutinize the doping effects of various dopants at different lattice positions. Our findings revealed that Mn replacing Fe and N replacing O are the most readily achievable doping methods under oxygen‐rich and oxygen‐poor conditions, respectively, with a maximum doping concentration of 1020 cm−3 achievable at 900 K. Interestingly, we found that doping with N for O, F for O, and Ni for Cu generates impurity levels capable of capturing photogenerated holes at the top of the valence band, while Zn for Cu and Co for Fe engender impurity levels capable of capturing photogenerated electrons at the bottom of the conduction band, thereby facilitating the separation of photogenerated electron–hole pairs. However, it is worth highlighting that Mn replacing Fe results in impurity levels forming in the middle of the bandgap, acting as a recombination center for photogenerated electron–hole pairs. Furthermore, we discovered that Mg replacing Cu or Fe serves as an example of heterovalent doping capable of promoting the solar‐to‐hydrogen conversion efficiency of CuFeO2. In isovalent doping, dopants with more valence electrons than Cu, dopants with the same valence electron as Fe, and dopants with less valence electron than O can enhance the solar‐to‐hydrogen conversion efficiency of CuFeO2. Overall, this study provides a systematic analysis of the doping effects on CuFeO2‐based photocatalysts and can be applied to doping engineering of ABO2‐type delafossite photocatalytic materials. [ABSTRACT FROM AUTHOR]

The development of CuFeO 2 photocathodes is hindered by challenges associated with low carrier separation and transport efficiency. In recent years, facet engineering has emerged as a promising solution to overcome these limitations. In this study, CuFeO 2 samples with varying crystal facets and morphology were successfully synthesized through precise control of hydrothermal reaction time, ultrasonic time, and the introduction of a surfactant. Among the synthesized samples, the nanosheet CuFeO 2 exhibited an impressive 83.36% exposure ratio of (001) facets and demonstrated the highest photocurrent density of 5.3 μA/cm2 when compared to both cubic CuFeO 2 with (012) facets and octahedral CuFeO 2 with (001) facets. The exceptional photoelectrochemical performance of the nanosheet CuFeO 2 can be attributed to the polar nature of the (001) crystal plane, which induces a surface polarization effect. This effect significantly enhances the separation efficiency of photoexcited electron-hole pairs. Additionally, the nanoscale dimensions of the CuFeO 2 nanosheets minimize carrier diffusion distances, leading to improved carrier transport efficiency. Overall, this study highlights the feasibility and immense potential of employing facet engineering as a strategic approach for enhancing the photoelectrochemical performance of CuFeO 2 photocathodes. The successful synthesis of CuFeO 2 samples with optimized crystal facets opens up new avenues for advancing the development of efficient photoelectrochemical devices. • Facet engineering offers new possibilities for enhancing the performance of CuFeO 2 photocathodes. • Nanosheet CuFeO 2 exhibits the highest photocurrent density of 5.3 μA/cm2 among the synthesized samples. • The nanosheet CuFeO 2 has an impressive 83.36% exposure ratio of (001) facets. • The polar nature of (001) crystal plane of nanosheet CuFeO 2 enhances carrier separation. [ABSTRACT FROM AUTHOR]

[Display omitted] • CuFeO 2 /CuO core-shell heterostructure achieves superior PEC performance compared to other tandem architectures. • CuFeO 2 @V O -CuO core-shell heterostructure shows 8-fold higher photocurrent density than CuFeO 2 alone. • Optimized process improves carrier concentration, transport, and electron-hole pair separation. • Enhanced interfacial electric field and oxygen vacancies in the CuFeO 2 @V O -CuO suppress recombination, improving PEC performance. This study aims to enhance the PEC properties of CuFeO 2 nanosheets by constructing closely bonded CuFeO 2 /CuO heterostructures. CuO crystal-structured films were prepared using the sol-gel spin-coating method, wherein the annealing temperature was varied to modulate the content of oxygen vacancies. Compared to pristine CuFeO 2 and two tandem architectures, the CuFeO 2 @V O -CuO core-shell architecture outperformed by yielding a photocurrent density of 68 μA/cm2, which marks an almost 8.5, 1.36 and 2.27 times enhancement. Experimental results verified solid atomic-level contact bonding at the CuFeO 2 @V O -CuO junction, thereby augmenting overall efficiency. Through the optimized fabrication process of the CuFeO 2 @V O -CuO core-shell heterostructure, carrier concentration and transport and electron-hole pair separation saw substantial improvement, further boosting its PEC performance. Critically, the presence of oxygen vacancies in the CuFeO 2 @V O -CuO heterostructure played a pivotal role. Oxygen vacancies eliminated potential traps for captured electrons at the interface and suppressed the formation of unoccupied interface states, reducing recombination of photogenerated electron-hole pairs. Moreover, oxygen vacancies facilitated conduction band alignment, promoting efficient separation and rapid transfer of photogenerated electron-hole pairs. In conclusion, the CuFeO 2 @V O -CuO core-shell heterostructure achieves efficient separation and transfer of photogenerated electron-hole pairs while effectively suppressing recombination, thanks to the synergy between the interfacial electric field and oxygen vacancies. [ABSTRACT FROM AUTHOR]

Abstract: The time domain transients of batteries comprised of LiFePO4 cathode material exhibit large nonlinearity with the increasing discharging rates. Hence, the calculated overpotential transients match the experimental determined well only when the discharging current is low enough. The results of electrochemical impedance spectra at different OCV level indicate that the change of the parameters of equivalent circuit or even the circuit architecture are probably responsible for the large discrepancy between the predicted and the measured transient profiles. By taking the change of equivalent circuit model at high discharging current into consideration, we successfully simulate the time domain transients of polarization within the entire discharging current range. Also with the help of circuit analysis, the contribution of the ohmic resistance, charge transfer impedance and solid-state diffusion impedance to total polarization has been differentiated as a function of discharging time. [Copyright &y& Elsevier]

Highlights: [•] Better ionic conductivities when 0.05≤ x ≤0.13. [•] model was preferred. [•] Grain size, lattice strain and Li+conductivity are closely related. [ABSTRACT FROM AUTHOR]

Layered LiNiCoMnO was synthesized by a citric acid assisted solid-state method. The structure and electrochemical properties of the LiNiCoMnO materials were investigated. XRD analysis indicated the as-synthesized LiNiCoMnO was with the layered α-NaFeO structure. The discharge capacity was about 154 m·Ahg at 0·1 °C rate in the range of 2·0-4·5 V. The kinetics of the LiNiCoMnO materials was investigated by the galvanostatic intermittent titration technique (GITT) method. The lithium ion diffusion coefficient of the LiNiCoMnO was determined in the range of 10 − 10cm· s as a function of voltage of 3·7−4·5 V. [ABSTRACT FROM AUTHOR]

Abstract: Lithium-ion battery cathode material Li1+ x V3O8 is synthesized by a citric acid/tartaric acid assisted sol–gel method and sintered at 350 °C, 450 °C and 550 °C for 3 h for the formation of Li1+ x V3O8 phase. The synthesized samples were fully characterized by FTIR, TG/DTA, XRD, SEM, EIS and charge–discharge tests. Li1+ x V3O8 material synthesized by tartaric acid assisted route and sintered at 450 °C for 3 h shows best electro-chemical performance. It shows a high initial capacity of 249 mAh g−1 and still reserves a discharge capacity of 260 mAh g−1 after 50 cycles. Moreover, in the case of tartaric assisted products, no capacity decadence is observed in 50 cycles. XRD together with TG/DTA measurements reveal that compared with citric acid assisted products, the adoption of tartaric acid as chelating agent effectively lowers the crystallization temperature of amorphous Li1+x V3O8. Therefore, precursors obtained by tartaric acid route calcinated at 450 °C for 3 h exhibit lower crystallinity and smaller grain size, which contributes to the better electrochemical performance of the cathode electrodes. From EIS measurements, the bulk resistance is reduced, which favors the intercalation and de-intercalation of lithium ions while cycling. [Copyright &y& Elsevier]

Abstract: Lithium-ion battery cathode material Li1+x V3O8 was synthesized by a tartaric acid assisted sol–gel method and thermally treated at 350°C, 450°C and 550°C for 3h for the formation of Li1+x V3O8 phase. The synthesized samples were fully characterized by FTIR, TG/DTA, XRD and charge–discharge tests. Li1+x V3O8 material synthesized by tartaric acid assisted route, followed by heat treatment at 450°C for 3h shows best electro-chemical performance. It shows a high initial capacity of 249mAhg−1 and still reserves a discharge capacity of 260mAhg−1 after 50 cycles. Moreover, for all tartaric assisted products, no capacity decadence is observed in 50 cycles. The in situ X-ray measurements reveal a two-phase transition mechanism in the lithium intercalation/deintercalation process. During lithium extraction, the structure of the delithiated compound changes from Li4V3O8 (x >3.1) to the original LiV3O8 phase (x <1.4) via the coexistence state of these two phases (1.4< x <3.2). An obvious contraction, especially at Li(3)–Li(4) transition, along a axis and a slight expansion along b axis are also observed. [Copyright &y& Elsevier]

The overdischarge behaviors of LiFePO, LiNiO, and LiMnO are thoroughly studied in different overlithiation voltage limitations. The results showed that LiFePO and LiMnO cathode materials show high structure stability under the overdischarge process to 1.0 V. The microstructure of LiNiO is vulnerable to breakdown under the same testing condition. Fe-based olivine and Mn-based spinel cathode materials show better cyclic calendar life than that of Ni-based layered material. When an extreme overdischarge parameter (down to 0.0 V) is applied, all three samples experience an electrochemically driven irreversible solid-state amorphization process. Due to this overlithiation reaction, the host structure is totally destroyed. Therefore, it is harmful to experience deep overdischarge behaviors for most cathode materials. [ABSTRACT FROM AUTHOR]

Abstract: A series of LiNi0.5Co0.5− x Ti x O2 (0⩽ x ⩽0.5) are prepared by a tartaric acid-assisted sol–gel technique. The phase formation process is observed by TG–DTA. It is found that the target product appears at a temperature higher than 400°C and completes to phase formation at 700°C. The crystal structure and morphology are characterized by XRD, SEM and Raman spectroscopy. XRD patterns show that the as-prepared sample transforms from hexagonal structure into cubic structure with the increase of Ti content in LiNi0.5Co0.5− x Ti x O2. Raman spectra also demonstrate the successive substitution of Ti for Co in the structure with band blue-shift phenomenon. SEM images confirm that the as-prepared sample exhibits narrow and regular particles with the size between 0.5 and 1.5μm. The apparent particle size of sample starts to decrease with x ⩽0.1, and the gradually increases by introducing Ti dopant with higher content (x ⩾0.15). The electrochemical behavior of the sample displays different characteristics after Ti substitution. It is found that the initial working potential increases with the increase of Ti doping content. As a result, the initial lithium storage capacity for trace Ti-doped sample is higher than that delivered by the pristine one. The decrease of reversible capacity for high degree Ti-doped sample is ascribed to the electrochemical inactivity of the cubic compound in the sample. Therefore, trace Ti doping is beneficial to achieve promising cathode material for lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: In this paper, Nano-sized hard carbon spherule (HCS) is prepared from the distilled water/ethylene glycol mixed solution by hydrothermal technique. Due to the addition of ethylene glycol, the as-prepared sample is a kind of nano-sized HCS and the particle size of nano-sized HCS is 50–100nm. Furthermore, nano-sized HCS displays larger specific surface area attributed to the well-dispersed property. As a result, it shows lower charge transfer impedance than that of micro-sized HCS owing to the huge contact area between particles and electrolyte. However, the initial coulombic efficiency of nano-sized HCS is a little lower than that of micro-sized HCS due to the large specific surface area for electrolyte irreversible decomposition. Charge-discharge cycling tests demonstrate that nano-sized HCS samples have high capacity retention ratio (92.7%) and high reversible lithium storage performance (525mAhg−1). Therefore, it is a potential anode material for lithium–ion batteries. [Copyright &y& Elsevier]

Abstract: The chemical and electrochemical stability of Cu current collectors in electrolyte for lithium-ion batteries is investigated. During long-term storage, the surface section of Cu foil is oxidized to copper compounds along with the reduction reaction of electrolyte. A continuous surface film can be formed on the Cu current collector after the foil is immersed in electrolyte for lithium ion batteries at room temperature for 30 days. This surface film is composed of inorganic compounds located in the inner layer and organic/inorganic mixed components stayed outside. It comes from the spontaneous reaction at the interface between Cu foil and electrolyte for the existence of trace water in electrolyte. Different from SEI film spontaneous formation during storage, surface film generated on Cu foil during electrochemical process shows different characteristic and mechanism. By using metal lithium as counter electrode, SEI film on Cu foil in Cu foil/metal Li battery is formed from surface chemical species floating from lithium counter electrode and electrochemical oxidation/reduction process. In contrast, thinner SEI film can be generated merely from electrochemical electrolyte decomposition and precipitation. All the evidences reveal that the structure of SEI film from different conditions is similar, which shows inorganic fluorides located in the inner layer and organic/inorganic mixed lied in the outer layer. [Copyright &y& Elsevier]

Abstract: Titania based ceramics are promising materials for environmental sensors, high efficiency photocatalyst. Ion doping is an effective method to improve the properties by modifying their microstructure and phase composition. In this study, TiO2 particles doped with Fe3+ were prepared by sol-gel method using Ferric nitrate and tetrabutyl titanate as precursors. Fe3+ was incorporated in the TiO2 matrix during thermal treatment in different temperatures. Thermal analysis, TEM and X-ray diffraction were used to characterize the TiO2 powder. Microstructure, phase content, and cell parameters were calculated according to Rietveld refinement software GSAS. The interaction mechanism of Fe3+ in crystal lattice of titanium dioxide and the crystal growth kinetics of Fe3+-doped TiO2 are discussed. [Copyright &y& Elsevier]

Abstract: The chemico–physical properties, near infrared and TG-DTA behavior of the non-crystalline silica prepared by water glass with different initial concentrations were systematically investigated. The structural parameters obtained by X-ray diffraction technique showed that the short range order was no more than 5–6 atoms. The variations of calculated co-ordination number and Si–O bond length, which to some extent reflected the structural compactness, explained the variation of the measured oil absorption well. [Copyright &y& Elsevier]

Abstract: The photocatalytic activity of titanium dioxide dispersions on X-3B pigment degradation has been investigated. A variety of factors that would influence the photocatalytic activity such as crystallite size, lattice distortion, and anatase content are discussed in detail. It is found that lattice distortion is the most important one among these factors and is expected to inhibit the hole and electron pair recombination. It determines, to some extent, the photocatalytic efficiency of titanium dioxide dispersions. [Copyright &y& Elsevier]

Three pairs of samples synthesized at ascending temperatures are investigated here, each including silica-coated calcium carbonate and its reference blank at a specific temperature. XRD results show that coated silicon dioxide is amorphous. The percentage of surface coated by silicon dioxide is proportional to the synthesizing temperature examined by XPS. Considering the possible application as an acetic proof composite material dispersed in polymer matrix for reinforcement and corrosion resistance, the London component of the surface energy, γSD, which to some extent is valuable in evaluating the particle–matrix interface, is intensively investigated by an inverse gas chromatography (IGC) at infinite concentrations. A preliminary explanation is given to account for the variation of γSD values with the column temperature. [Copyright &y& Elsevier]

Calcium carbonate was surface treated by acrylic acid monomer, its polymerization with varied mean molecular weight and PS/PAA copolymer. Coating efficiencies for these four series of surface-treated calcium carbonate were investigated. They differ from each other in many aspects. We hypothesize that the treating molecules bond to and align on the particle surface in different ways before and after monolayer coverage was reached. NIR spectra of surface-treated samples studied not only reflected the amount of bonded treating agents by means of the value of absorbance, but also gave rich structural information of surface layer. This gave us a powerful means to investigate the interface of particle surface. [Copyright &y& Elsevier]

The efficacy of the surface treatment of particulate fillers depends on the chemical character of the components, on the method and conditions of the treatment, and on the amount of the treating agent. Here, the ultra-fine calcium carbonate is surface treated with 1, 2, 3 and 4 wt.% polyacrylic acid (PAA) synthesized by ourselves, which has strong ionic interaction and is an efficient surface modifier. The PAA coated filler is submitted to the measurement of the surface bonded amount, bonding efficacy, X-ray photoelectron spectroscopy (XPS) and inverse gas chromatography. Maximum efficacy is expected at the monolayer coverage of the surface, which is about 0.6 wt.% according to the calculation based on the way they are aligned and is basically in agreement with the “substrate overlayer” model based on the mole ratio of C286 and C290 taking no account of the possible underestimation because of the inaccuracy or because of the CHx contamination present originally on the CaCO3. The initial decrease of the mole ratio of C290/O and C290/Ca with the surface bonded PAA may indicate that the bonding interaction between the polymer and the filler surface is the leaving of one molecular carbon dioxide. The IGC measurement shows that there is a considerable surface tension falling in the case of the PAA modified filler compared with the reference. An abnormal high surface energy in the case of filler treated with 4% PAA is observed. [Copyright &y& Elsevier]

The model-free and model fitting approaches have been applied to the data for non-isothermal decomposition kinetics of SiO2 surface coated calcium carbonate as well as the reference. The decomposition mechanisms as revealed by computation show great differences. Nano-sized reference samples decompose according to the contracting volume mechanism (R3) while the surface SiO2 coated calcium carbonate shows the one-dimensional diffusion (D1) behavior, possibly because of the framework constituted by surface SiO2 layer hinders the diffusion of the dissociate products into the outer atmosphere. At the mean time, the activation energy is increased by 30–35 kJ/mol in the process controlled by diffusion compared with the reference. However, the usual model fitting approach may also yield highly uncertain values of Arrhenius parameters when applied to non-isothermal data, so that a combination of master plot method and model-free kinetic approaches based on the isoconversional method that yields the dependencies of the activation energy on the extent of the conversion were also used to evaluate the credulity of the kinetic parameters achieved by model fitting methods. [Copyright &y& Elsevier]

In this study, three ultra-fine calcite samples having similar particle size but presenting different agglomeration state were synthesized. SEM and TEM measurements, Infrared and Raman analysis were used to view how the structure may possibly affect their spectrum characteristics. [ABSTRACT FROM AUTHOR]

Spinel structured α-LiFe 5 O 8 were prepared via ball milling combined with a straightforward solid-phase method, using Fe 2 O 3 and Li 2 CO 3 as the raw materials. The material maintained a stable capacity of 440 mAh g−1 after 200 cycles at 900 mA g−1 with Coulomb efficiency more than 95 % and also showed facile lithium ion diffusion dynamics. The calculated diffusion coefficient of α-LiFe5O8 ranged around 10−10-10−12 cm2 s−1. Diffusion controlled contribution was dominant over capacitive contribution in the sweeping range 0.1–1.5 mV s−1. A new intercalation-decomposition-conversion mechanism was proposed on the basis that there existed a small pit at the initial stage of the discharge plateau and a significantly low initial discharge plateau voltage was observed compared with the followed discharge cycles. Based on the DFT calculations and the phase diagram of the Li–Fe–O system, we supposed that for the initial discharge of the material, after 1 mol of lithium ion intercalation per unit formula, α-LiFe 5 O 8 decomposed to LiFeO 2 and Fe 3 O 4. The followed discharge was the conversion of both LiFeO 2 and Fe 3 O 4 to metal Fe and Li 2 O. Thereafter, the system cycled between Fe 2 O 3 at the fully charged state and metal Fe and Li 2 O at the fully discharged state. Li–Fe–O phase diagram used to disclose the conversion mechanism. [Display omitted] • Unmodified α-LiFe 5 O 8 show good electro-chemical performance. • Li+ transportation kinetics reveals the features of fast ion conductor. • A new intercalation-decomposition-conversion mechanism was proposed. [ABSTRACT FROM AUTHOR]

The current study aimed to explore the association of cognitive emotion regulation, social support, resilience and acute stress responses in Chinese soldiers and to understand the multiple mediation effects of social support and resilience on the relationship between cognitive emotion regulation and acute stress responses. A total of 1477 male soldiers completed mental scales, including the cognitive emotion regulation questionnaire-Chinese version, the perceived social support scale, the Chinese version of the Connor-Davidson resilience scale, and the military acute stress scale. As hypothesized, physiological responses, psychological responses, and acute stress were associated with negative-focused cognitive emotion regulation, and negatively associated with positive-focused cognitive emotion regulation, social supports and resilience. Besides, positive-focused cognitive emotion regulation, social support, and resilience were significantly associated with one another, and negative-focused cognitive emotion regulation was negatively associated with social support. Regression analysis and bootstrap analysis showed that social support and resilience had partly mediating effects on negative strategies and acute stress, and fully mediating effects on positive strategies and acute stress. These results thus indicate that military acute stress is significantly associated with cognitive emotion regulation, social support, and resilience, and that social support and resilience have multiple mediation effects on the relationship between cognitive emotion regulation and acute stress responses. [ABSTRACT FROM AUTHOR]

Herein, sol–gel-synthesized α-Li2TiO3 was evaluated as a new promising anode material for lithium-ion batteries. The results show ultrastable release of discharge capacity within the range of 290–350 mA h g−1 in 400 cycles. Decent rate performances were also observed. A capacity of ca. 113 mA h g−1 was retained at a current density of 3 C. A 2 × 2 × 1 supercell of the lowest energy ordering structure was used in density functional theory simulations. The calculations show that in the intercalation process, Li+ preferentially enters the tetrahedral voids, leading to the activation of lithium-ion diffusion on the a–b plane with a minimal energy barrier of 0.06 eV (compared with 0.82 eV for the fully charged state). The activation of cation mobility at Li+ intercalation and insulator–conductor transition both contribute significantly to the ultrastability of the material. However, Li+ propagation along the c-axis is highly limited during the whole intercalation process. The enumeration of all the ordering structures on the tetrahedral sites shows two intermediate phases, α-Li2.25TiO3 and α-Li3.0TiO3, as observed from the formation energy convex hull. [ABSTRACT FROM AUTHOR]

Among a variety of host materials for lithium storage, titanium-niobium oxides exhibit great potential in application. Herein, Ti 2 Nb 10 O 29 nanowire is synthesized via an electrospinning method. Compared with bulk Ti 2 Nb 10 O 29 prepared by solid-state approach, the electrochemical properties of Ti 2 Nb 10 O 29 nanowire is better. According to the galvanostatic charging-discharging test, the initial capacity of 232.8 mAh g−1 for Ti 2 Nb 10 O 29 nanowire is displayed. Besides, it exhibits superior rate performance. With the current density set as 0.5, 1, 2, 3, 4 and 5 C, the Ti 2 Nb 10 O 29 nanowire can deliver the specific capacity of 251.3, 240.3, 221.8, 205.3, 188.1 and 174.5 mAh g−1, respectively. Furthermore, its cycling performance is superior. The capacity retention of Ti 2 Nb 10 O 29 nanowire is 85.90% after 900 cycles at 12 C, which is obviously superior than that of bulk Ti 2 Nb 10 O 29 (25.16%). Finally, a Ti 2 Nb 10 O 29 /LiCoO 2 full cell is fabricated, which exhibits excellent electrochemical performance, demonstrating its potential for practical application. [ABSTRACT FROM AUTHOR]

Recent experiments showed that by fabricating nanofluidic channels with hydrophobic materials, the measured amplitudes of both electroosmotic flow (EOF) and ionic current deviated significantly from the conventional electrokinetic modeling indication. Among these unexpected observations, the complicated dependence of EOF on the surface charge concentration of the channel wall remains most confusing. In this work we give a complete and unified picture for the phenomena by outlining the competing two mechanisms in the water-depletion layer around the channel wall: the decreasing trend of fluidic flow due to the redistribution of net charges, and the increasing trend because of the reduced solution viscosity there. Our quantitative evaluation illustrates that the alternate dominating by the two mechanisms leads to the observed transport behaviors. Furthermore, by considering the decreasing of ionic mobility in the depletion layer, our calculations show quantitative agreement with the latest experiments using BN nanotube channels. [ABSTRACT FROM AUTHOR]

Titanium niobate prepared by traditional techniques has the shortcomings of low ion diffusion coefficient as well as poor electrical conductivity, which drastically reduce its applicability. In this work, we prepare carbon coated Ti 2 Nb 10 O 29 hollow submicron ribbons (Ti 2 Nb 10 O 29 @C HSR) using a simple electrospinning procedure. As anode material for lithium-ion batteries (LIBs), it delivers a high charge capacity of 259.7 mAh g−1 at 1 C with low capacity loss of 0.013% in long-term cycles. Increased the current density to 5 C, Ti 2 Nb 10 O 29 @C HSR can maintain a reversible capacity of 189.9 mAh g−1, indicating its good rate performance. Additionally, this work uses in-situ X-ray diffraction (XRD) to provide an explanation for the lithium storage process in Ti 2 Nb 10 O 29 @C HSR, demonstrating the high reversibility during charge/discharge cycles. Therefore, Ti 2 Nb 10 O 29 @C HSR has outstanding cycle adaptability and structural reversibility to be a promising anode for LIBs. [ABSTRACT FROM AUTHOR]

Cathode material 0.5Li 2 MnO 3 ·0.5LiNi 0.5 Mn 0.5 O 2 is successfully synthesized by citrate acid assisted sol–gel method and shows pretty good electro-chemical performance. To elucidate the electro-chemical reactions and charge carrier transportation kinetics in the charge–discharge process, series of electro-chemical impedance spectra for the first and the second charge process are measured on multiple given state of charges. The rapid augmentation of resistance to electronic conduction and ionic conduction within the voltage range 4.45–4.6 V where the removal of Li 2 O from Li 2 MnO 3 component takes place gives us more evidence about the complicated “structurally integrated” feature of this material. The relatively large span of the arc responsible for electronic conduction and the extremely large Mn 3+ related charge transfer resistance at the beginning of the second charging indicate that after one complete charge–discharge cycle, Li 2 MnO 3 and LiNi 0.5 Mn 0.5 O 2 domains still reserve its original structure and will keep its structure for the followed cycles. [ABSTRACT FROM AUTHOR]

LiFePO 4 cathode material prepared by solid state carbo-thermal reduction exhibited pretty good electro-chemical performance. It showed an initial discharge capacity of 152.6 mAh·g − 1 and only 2.3% capacity fading was observed after 50 cycles. The coulomb efficiencies were between 98 and 100%. The electrochemical impedance spectroscopy measured at series of equilibrium potentials within the voltage range 2.5–4.5 V showed that they were highly voltage dependent. This indicated the different kinetics steps of charge carrier transportation through the whole battery components. The coefficients of lithium ions and polarizations of charge carrier transportation as a function of equilibrium potentials were determined from the EIS profiles. An inverted V shaped curve was observed as to the relation between the lithium diffusion coefficient and equilibrium potential. However, contrary to the previous reports, based on Einstein equation, the lithium ion diffusion in the phase transition region from LiFePO 4 to FePO 4 was calculated to be in the range 10 − 11 –10 − 12 cm·s − 1 , which was about 1–2 order of magnitude larger than that of other region. [ABSTRACT FROM AUTHOR]

A series of Nasicon-type solid electrolytes Li1+2x+2y Al x Zn y Ti2−x−y Si x P3−x O12 was synthesized by conventional solid state ceramic route. X-ray diffraction and Rietveld whole pattern refinement were applied to investigate the phase, structure and the unit cell parameters of those solid electrolytes. EIS complex impedance method was carried out to study the Li+ conductivity. The results showed that Li1+2x+2y Al x Zn y Ti2−x−y Si x P3−x O12 with x=0.1 y=0.5 presents highest ionic conductivity 7.2×10−5 Scm−1 at ambient temperature and 2.0×10−3 Scm−1 at 473K. The activation energy of Li+ migration was calculated to be ca. 20kJmol−1. The influence of Zn2+ element on the structure and Li+ mobility was preliminary explained. [ABSTRACT FROM AUTHOR]

Nanometer-sized FeF3·0.33H2O/acetylene black composite has been synthesized by one step chemico-mechanical ball-milling process using Fe (NO3)3∙9H2O and NH4F as precursors and investigated as cathode materials for secondary lithium batteries. The obtained FeF3·0.33H2O/C composite was described in terms of structure, morphology, and electro-chemical performance. The composite exhibited a noticeable capacity of 233.9mAhg−1 at a current density of 20mAg−1 within potential range 1.8–4.5V and good rate capability. These results showed that FeF3·0.33H2O/C nano-composite prepared from an easily scalable chemico-mechanical ball-milling process was of great industrial interest. [ABSTRACT FROM AUTHOR]

The perovskite-type oxide LixLa(2-x)/3TiO3 (LLTO) was prepared by high temperature solid-phase method as an high power and long cycling life negative electrode material for lithium-ion battery. Compared to the previously reported LLTO series anode materials, Li0.2375La0.5875TiO3 shows higher capacity and cycle stability, which delivers a reversible discharge capacity of 270 mAh g−1 at a current density of 100 mA g−1 and retained 258 mAh g−1 after 1000 cycles. Moreover, excellent rate performance is also shown. It delivers a charge capacity of ca. 241.3, 186.8, 165.2, 145.2 and 246.4 mAh g−1, respectively, at the end of each 10 cycles at the current density of 100, 500, 1000, 2000 and back to 100 mA g−1. The molecular dynamics (MD) simulations based on a special quasi-random structures (SQS-64) super cell confirm the direct Li+ migrations between neighboring Li+/vacancies. The metallic nature of the Li0.2375La0.5875TiO3 is one of the important factors that improve the performance of the sample. Most important of all, the highly active Li+, which is ca. 10–9 cm2 s−1 from Cyclic voltammetry/Electro-chemical impedance spectroscopy (CV/EIS) results and ca. 10–7 cm2 s−1 from MD simulations, and the vacancies at 1a/1b sites, which facilitate the migration of two neighboring lithium ions, also greatly contribute to the high performance of the material. (a) The a view of the superimposed Li+ trajectory at 600 K (b) The b view of the superimposed Li+ trajectory at 1200 K of the 2×2×2 SQS-64 demonstrating the lithium ion diffusion mechanism of Li0.2375La0.5875TiO3. [ABSTRACT FROM AUTHOR]

Abstract: The electronic property and structural stability of LiMn2O4 and LiNi0.5Mn1.5O4 with Fd m space group are investigated by density functional theory (DFT) plane-wave pseudopotential method. The calculated values of Mn(Ni)–O bond lengths are found to be consistent with the reported experimental values. Due to the Ni doping, the significant shortening of Mn(Ni)–O bond strengthens the structural stability of spinel. The electronic properties of spinel show that the bonding between O and metal (Mn and Ni) is also strengthened due to the Ni doping, and then it improves the structural stability of LiNi0.5Mn1.5O4. Ni-doped spinel has a lower formation enthalpy than that of the pristine, indicating that the Ni doping improves the structural stability of spinel. [ABSTRACT FROM AUTHOR]

Spherulitic calcium carbonate composite is synthesized in the solution of amphiphilic block copolymer PS-b-PAA. FE-SEM and XRD measurements show that the size of the particulates decrease with the augment of PS-b-PAA concentration, and the morphology as well as the crystalline structure are changed too. TG-DTA together with IR analysis is applied to investigate the thermal dynamic behavior of the composite. The results show that the composite is mainly composed of two phases, that is, the nanocrystalline calcium carbonate and the PS-b-PA–Ca composites. In DTA curves, PS phase decomposes first with a large heat release at the temperature range between 300 and 400 °C. However, the PAA chains have relatively higher thermal stability, probably due to the structural Ca&z.sbnd;O bond, and decompose between 400 and 500 °C. The above studies on the morphology and crystal structure of the calcium carbonate and the thermal stability indicate that the micellization of amphiphilic block copolymers, the stretching of ionized PAA chains and the preferential induction of neighboring carboxyl group on the precipitation of calcium carbonate may cause the formation of the spherulitic composite. [Copyright &y& Elsevier]

In aqueous/nonaqueous metal‐sulfur batteries, sulfur‐based redox couple exhibits significant challenges mainly due to its low electrochemical kinetics, potential shuttle effect, and large volume change. Although massive researches have been conducted to optimize or replace metal anode and cathode composite, major challenges caused by the dependency on sulfur‐based redox couple still remain. In this study, a novel redox couple of CuS/Cu2S, which provides the same theoretical capacity (based on conventional S/S2− redox couple) by changing the valence of ion charge carrier, is proposed. For achieving high reversibility, commercially viable laser‐induced graphene (LIG) is fabricated and used for the first time in aqueous metal‐sulfur batteries. By virtue of the synergism between novel redox couple and LIG, aqueous CuS/Cu2S battery delivers a highly reversible capacity of 1654.9 mAh g−1 in the initial cycle and retains 91.2% with 1509.5 mAh g−1 after 328 cycles. When being cycled at 2.8 A g−1, its reversible capacity still retains 92.1% after 410 cycles. This study provides a new choice by using a sulfur‐free redox couple from screening thermodynamic parameters and analyzes the functional mechanism of LIG by density functional theory, aiming to innovate the energy storage mechanism of aqueous metal‐sulfur batteries. [ABSTRACT FROM AUTHOR]

Herein, we propose a new anode material, PbNb 2 O 6 , for use in lithium-ion batteries. PbNb 2 O 6 can be synthesized via a simple and traditional solid-state method. The as-prepared powder exhibits an average size distribution of about 0.5 μm. When tested in a lithium-ion cell, the PbNb 2 O 6 electrode can exhibit a charge capacity of 245.2 mAh g−1 at 200 mA g−1, and after 80 cycles, the capacity can retain a charge capacity of 181.4 mAh g−1, showing 0.32% capacity fading per cycle. Furthermore, the capacity of the PbNb 2 O 6 electrode is 223.1 mAh g−1, even when cycled at 1000 mA g−1, and a capacity of 150.7 mAh g−1 is maintained up to 500 cycles. In addition, the lithiation mechanism of PbNb 2 O 6 is investigated via various techniques. Interestingly, PbNb 2 O 6 exhibits high capacity without the contribution of two redox couples of niobium after the initial cycles. Finally, all Results suggest that PbNb 2 O 6 has potential for use as an electrode in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

With the development of electric vehicles, more and more attention has been paid to the kinetic performance of batteries, which is related to rapid charge/discharge and safety issues. To improve this aspect, Cu2Nb34O87 nanowires covered by nitrogen and sulfur co-doped carbon (Cu2Nb34O87/NSC nanowires) are prepared by electrospinning combined with surface coating. As-prepared Cu2Nb34O87/NSC nanowires present a high ion diffusion coefficient and electronic conductivity, showing good a kinetic performance. Specifically, they deliver a splendid capacity of 311.2 mA h g−1 at 1 C and a superior cycling stability with a capacity fading of 0.031% per cycle upon 1000 cycles. At the same time, the electrochemical and structural reversibility is fully discussed and demonstrated by ex situ XRD, ex situ SEM and ex situ XPS based on the redox couples of Cu2+/Cu+, Nb5+/Nb4+, and Nb4+/Nb3+. Contributing to peculiar physico-chemical properties, Cu2Nb34O87/NSC nanowires are expected to be a candidate material for the anode in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Hydrolytic dehydrogenation of Ammonia-borane (NH 3 BH 3 , abbreviation AB) has attracted much attention due to its high hydrogen content and stability. Therefore, the design and construction of low cost and high performance catalysts for AB hydrolysis are of great significance. In this work, a series of RhCu/CoO x alloy catalysts were prepared by a in-situ reduction method. The catalytic activity of hydrolytic dehydrogenation of AB was optimized by regulating the molar ratio of Rh to Cu in the RhCu/CoO x catalysts. The results verify that Rh 1 Cu 2 /CoO x has the best catalytic activity for hydrolytic dehydrogenation of AB, and the corresponding hydrolysis reaction type was first order. The turnover frequency (TOF) reached 670.95 mol H 2 mol cat − 1 min−1, and the apparent activation energy (Ea) was 28.86 kJ mol−1, showing excellent catalytic performance for hydrolytic dehydrogenation of AB. The ultra-small RhCu alloy nanoparticles were synthesized Rh 1 Cu 2 /CoO x catalysts with a facile in-situ reduction method, showing the optimal catalytic performance for hydrolytic dehydrogenation of ammonia borane. The corresponding turnover frequency (TOF) was 670.95 mol H 2 mol cat − 1 min−1, and the apparent activation energy (Ea) was only 28.86 kJ mol−1. [Display omitted] • RhCu alloys were successfully loaded onto CoO x carrier by in-situ reduction method. • Rh 1 Cu 2 /CoO x shows excellent catalytic performance for hydrolytic dehydrogenation of AB. • The high turnover frequency of 670.95 min−1 was achieved at room temperature. [ABSTRACT FROM AUTHOR]

Nowadays, it is of great urgency to research for appropriate materials to construct high-performance lithium-ion batteries (LIBs) because of the growth of social demand. Among them, niobium type metal oxides are potential candidates for anode materials. Here, we propose GaNb 11 O 29 with shear-ReO 3 crystal structure as anode material. It is an intercalation-type material with high theoretical capacity and safe working voltage. In this work, GaNb 11 O 29 nanowires are synthesized by electrospinning. The nanostructure design can effectively improve lithium storage behavior. Accordingly, GaNb 11 O 29 nanowires provide a high reversible capacity (233.4 mAh g-1 at 100 mA g-1), outstanding rate capability (168.8 mAh g-1 at 700 mA g-1) and superior long-term stability (0.031% capacity loss per cycle after 500 cycles). Furthermore, the kinetic analysis confirms the pseudocapacitive contribution during cycling, which contributes to the rapid Li-storage. In addition, in-situ XRD characterization is conducted to further unveil the Li-storage mechanism in lithiation/delithiation processes. This work suggests that GaNb 11 O 29 nanowires are potential anode material for rechargeable batteries, which enriches the choice for high-performance LIBs. [ABSTRACT FROM AUTHOR]

Advanced electrode materials with excellent electrochemical properties have always been widely concerned in lithium-ion batteries (LIBs). In this work, two kinds of CrNb 49 O 124 nanowires of different sizes are prepared via electrospinning technique with two different solvents (ethanol and dimethylformamide). Moreover, the obtained CrNb 49 O 124 nanowires are nitrided by thermal ammonia gas to further improve the electrochemical performance. And it is pleasantly surprised to say that the nitrided CrNb 49 O 124 nanowires perform better than our expectation. It exhibits an initial Coulombic efficiency up to 90.72%, and an eximious charge specific capacity (273.6 mAh g−1), which is apparently higher than that before nitridation. In addition, after 300 cycles at 1 C, it still maintains capacity of 224.4 mAh g−1 and the retention is up to 90.41%, indicating its excellent long cycling stability. The outstanding electrochemical properties of nitrided CrNb 49 O 124 nanowires are proved to be much superior than most of anode materials in LIBs. Meanwhile, it is successfully confirmed that nitridation technique can be an efficient approach for high-performance energy storage applications to promote electrochemical properties of most electrode materials. [ABSTRACT FROM AUTHOR]

The GaNb 11 O 29 shows an open Wadsley-Roth shear structure, which is of great benefit to store ions in rechargeable batteries. In this work, we successfully synthesize GaNb 11 O 29 @C via a simple solid-state reaction method combined with carbon-coating modification. As anode for LIBs, the as-synthesized GaNb 11 O 29 @C sample exhibits wonderful electrochemical behaviors. It exhibits high reversible capacity (227.3 mA h g−1), outstanding rate capability (58.91% retention at 700 mA g−1) and excellent long cycle performance (0.036% capacity decay per cycle). The enhancement of diffusion kinetics and rate performance assigns to the increased surface reaction activity and electrical conductivity. The open and stable crystal framework structure guarantees rapid lithium-ion migration, excellent rate performance and long cycle performance. These results tell that GaNb 11 O 29 @C is promising anode material for the application in advanced LIBs. [ABSTRACT FROM AUTHOR]

• TiNb 6 O 17 nanospheres are prepared by electrostatic spraying. • TiNb 6 O 17 nanospheres show superior electrochemical performance than the bulk. • A reversible capacity of 159.1 mAh g−1 can be delivered after 150 cycles at 0.5 C. • The electrochemical kinetics of TiNb 6 O 17 nanospheres are investigated by CVs. • Li-storage process of TiNb 6 O 17 nanospheres is analyzed by in-situ XRD. This work reports the preparation of TiNb 6 O 17 nanospheres via a facile electrostatic spraying route and their lithium storage mechanism. When selected as anode material in half-cell, TiNb 6 O 17 nanospheres possess the high capacity, extraordinary rate performance, and outstanding cyclability. The results exhibit that TiNb 6 O 17 nanospheres deliver an initial discharge capacity of 245 mAh g−1 with a high Coulombic efficiency of 86.37% at 0.5 C, and even after 150 cycles, a reversible capacity of 159.1 mAh g−1 is kept with Coulombic efficiency close to 100%. The outstanding electrochemical properties of TiNb 6 O 17 nanospheres can be ascribed to their unique morphologies. In addition, the electrochemical kinetics of TiNb 6 O 17 nanospheres is investigated by cyclic voltammetry. The results indicate that their electrochemical behavior is composed of two parts, lithium ion diffusion and pseudo-capacitive characteristic. Furthermore, lithium ion storage mechanism of TiNb 6 O 17 nanospheres is studied by in situ X-ray diffraction instrument, revealing superior electrochemical reversibility and structure stability. Based on the aforementioned measurements, it can be concluded that TiNb 6 O 17 nanospheres have the potential for practical use in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Ultra-stable anode materials for lithium-ion batteries are increasing in demand as highly sustainable energy storage system with excellent charge transport becomes unprecedentedly important. Here, a novel Li-ion full cell, utilizing BNb 3 O 9 hollowed-out nanobelts as the typical intercalation anode and commercial LiFePO 4 as the cathode in organic electrolyte, is reported. Moreover, the hollowed-out framework of BNb 3 O 9 nanobelts, prepared by an adjustable-voltage electrospinning method, exhibits prominent cyclic stability (116.1 mAh g−1 at 700 mA g−1 (12C) over 1000 cycles) and outstanding rate capability (126.8 mAh g−1 at 900 mA g−1) in half cell. The key finding is that the formation mechanism of BNb 3 O 9 hollowed-out nanobelts can be thoroughly discussed by scanning electron microscope. The contribution of the external pseudocapacitance largely affects the rate capability, which is determined via kinetic analysis. Furthermore, the lithium storage mechanism and structural evolution of BNb 3 O 9 are investigated through in-situ X-ray diffraction. Such preeminent electrochemical performance and distinctive morphology endow BNb 3 O 9 hollowed-out nanobelts with potentials as anode materials for lithium-ion batteries. Image 1 • BNb 3 O 9 hollowed-out nanobelts are formed by an adjustable-voltage electrospinning. • BNb 3 O 9 hollowed-out nanobelts show superior performance to the microparticles. • LiFePO 4 /BNb 3 O 9 cell presents 66% capacity retention after 200 cycles at 700 mA g−1. • Structural evolution of BNb 3 O 9 upon lithiation is analyzed by in situ XRD. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • AgNb 13 O 33 is synthesized and applied as lithium host for the first time. • AgNb 13 O 33 shows a high storage capacity of 329.4 mAh g−1 above 1.0 V. • Structural evolutions of AgNb 13 O 33 are investigated by in-situ and ex-situ routes. Abstract Anode materials for lithium ion batteries with environmental benignity and great electrochemical performance are greatly desired. In this work, AgNb 13 O 33 with open framework is reported as an anode material for the first time. It shows a triclinic lattice with 4i, 4f sites and 8j sites for lithium storage. At the current density of 100 mA g−1, AgNb 13 O 33 delivers high initial charge/discharge capacity of 329.4/357.8 mAh g−1 with an initial Columbic efficiency of 92.06%. 500 cycles later, it still remains a reversible capacity of 214.2 mAh g−1. Moreover, at a higher rate of 1000 mA g−1, AgNb 13 O 33 still maintains an initial charge capacity of 203 mAh g−1. Ex-situ transmission electron microscope (TEM) and in-situ X-ray diffraction (XRD) tests are performed to study the lithiation and delithiation reactions of AgNb 13 O 33 during the cycling. The reversibility and structural stability of the AgNb 13 O 33 make contributions to its excellent performance. All results show the promising possibility of applying AgNb 13 O 33 as an anode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract La 2 (MoO 4) 3 is a kind of transition metal molybdate. It has been proved to be a possible anode material for lithium ion batteries due to the high theoretical capacity. In this work, molybdenum-based La 2 (MoO 4) 3 material is successfully synthesized through a traditional solid-state reaction method. Carbon-coated La 2 (MoO 4) 3 is designed by using glucose as carbon source. By comparing the carbon-coated La 2 (MoO 4) 3 with the carbon-free La 2 (MoO 4) 3 , carbon-coated La 2 (MoO 4) 3 delivers better cyclic stability and rate performance. Carbon-coated La 2 (MoO 4) 3 obtains a reversible charge capacity of 525.9 mA h g−1 at 100 mA g−1 after 100 cycles, corresponding to capacity retention of 75.2%. However, the capacity retention of carbon-free La 2 (MoO 4) 3 is only 33.4%. The results indicate that carbon layer can evidently alleviate the irreversibility of structure and improve capacity retention of La 2 (MoO 4) 3. It demonstrates that the carbon-coated La 2 (MoO 4) 3 composite can be a possible anode candidate for high capacity lithium ion batteries. In addition, in-situ X-ray diffraction investigation (XRD), ex-situ X-ray photoelectron spectroscopy (XPS), and ex-situ transmission electron microscopy (TEM) are employed to analyze the electrochemical behavior during process of cycling. These experimental results indicate that the conversion behavior of La 2 (MoO 4) 3 upon lithiation/delithiation is a process of structural pulverization. Based on that, our work provides guidance for the research of molybdenum-based electrode materials. [ABSTRACT FROM AUTHOR]

Abstract Bismuth-based materials are promising alloy-type materials as lithium-ion batteries (LIBs) anode with a high theoretical capacity of about 385 mAh g−1 (Li 3 Bi). However, the severe volume change during the charge/discharge process limits their applications in LIBs. Nanostructured design is an effective strategy to relieve the volume change. Here, Bi 5 Ni 3 O 15 nanowires are designed and fabricated via a sample electrospinning technique. When used as anode material, the Bi 5 Ni 3 O 15 nanowires exhibit a charge/discharge capacity of 372 and 636 mAh g−1 at current density of 100 mA g−1. After 100 cycles, it still retains a capacity of 267 mAh g−1, revealing a good electrochemical performance. This is mainly attributed to the nanostructured design, which can suppress the pulverization resulting from volume variation during the repeated alloy/dealloy process and offers shorter lithium-ion diffusion path together. In addition, in-situ X-ray diffraction experiments are carried out to explore the phase change and lithium storage mechanism. The exploration of Bi 5 Ni 3 O 15 nanowires as LIBs anode demonstrates that nanostructured design is an effective approach to improve electrochemical performance of alloy-type anodes, which will speed up the process to develop novel alloy-type anodes. Graphical abstract Image 1 Highlights • Bi 5 Nb 3 O 15 nanowires are synthesized by electrospinning. • Bi 5 Nb 3 O 15 nanowires are first reported as anode material. • Nanostructured design can improve the cycling life of bismuth-based anodes. • Alloying/dealloying behavior of Bi 5 Nb 3 O 15 are demonstrated by in-situ XRD. [ABSTRACT FROM AUTHOR]

Abstract In this study, microsized WNb 60 O 153 bulks and nanostructured WNb 60 O 153 nanowires have been successfully prepared through solid-state reaction and electrospinning technique. Contributed to nanostructured architecture, WNb 60 O 153 nanowires have better performance than microsized WNb 60 O 153 bulks, which is verified by the comparison of galvanostatic charge/discharge experiment, cyclic voltammetry and electrochemical impedance spectroscopy and high-rate analysis. Revealed by electrochemical measurements, WNb 60 O 153 nanowires deliver a higher specific capacity of 174 mAh g−1 at 100 mA g−1 than that of microsized WNb 60 O 153 bulks (153 mAh g−1). Furthermore, it can reach a capacity of 134 mAh g−1 at a higher rate of 1000 mA g−1. It is worth mentioning that the longer cycle life, superior rate performance and higher reversible capacity is contributed to the great lithium-ion diffusion coefficient of WNb 60 O 153 nanowires, which are also higher than other Nb-based compounds and conventional Ti-based anode materials. In addition, in situ X-ray diffraction (XRD) technique is carried out to further elucidate the structural stability and reversibility for the WNb 60 O 153 nanowires. All the evidences prove that electrospun WNb 60 O 153 nanowires can be employed as an alternative electrode material for the lithium-ions batteries (LIBs). [ABSTRACT FROM AUTHOR]

Abstract The tungsten niobium oxides that belong to the well-known Wadsley-Roth shear structure have been already studied as the high-performance anode materials over the past several years since these materials can provide the additional vacuum site for accommodating lithium ions. Now, a novel anode material Nb 18 W 16 O 93 which has a tetragonal tungsten bronze type structure is firstly reported in this paper. This material exhibits the good electrochemical performance. Upon the modification of its surface morphology, the electrochemical performance for Nb 18 W 16 O 93 nanowire has been greatly improved. Nb 18 W 16 O 93 nanowire shows the reversible specific capacity of 195 mAh g−1 when the current density is 100 mA g−1 and it can reach 153 mAh g−1 even at 1000 mA g−1. Meanwhile, the lithiation/delithiation mechanism and its corresponding structural change during the charge and discharge process are also carried out by an in-situ XRD technique. The result shows that Nb 18 W 16 O 93 nanowire has excellent electrochemical reversibility and structural stability. Consequently, Nb 18 W 16 O 93 nanowire can be employed as a novel anode material for lithium ion batteries. Graphical abstract Image 1 Highlights • Nb 18 W 16 O 93 nanowires are prepared by a facile electrospinning method. • Nb 18 W 16 O 93 nanowires show better electrochemical performance than the bulks. • Nb 18 W 16 O 93 nanowires deliver a capacity of 153 mAh g−1 at 1000 mA g−1. • Structural evolution of Nb 18 W 16 O 93 during lithiation is analyzed by in-situ XRD. [ABSTRACT FROM AUTHOR]

Lithium ion batteries (LIBs), sodium ion batteries (SIBs) and potassium ion batteries (PIBs) can be proposed as substitutes to fossil fuels because of the gradual depletion of non-renewable energy. In this work, Pb 3 Nb 4 O 13 is investigated as a new kind of anode material with the storage ability of lithium, sodium and potassium. Pb 3 Nb 4 O 13 nanowires are prepared via a feasible electrospinning technique followed with calcinations. Furthermore, it's the first time for Pb 3 Nb 4 O 13 to be applied as anode materials. At the current density of 50 mA g −1 , Pb 3 Nb 4 O 13 shows reversible capacities of 264.8, 171.4 and 100.1 mA h g −1 in the applications of LIBs, SIBs and PIBs, respectively. In addition, the storage mechanisms of Pb 3 Nb 4 O 13 in different batteries are also investigated by in situ XRD. The results show that Pb 3 Nb 4 O 13 nanowires have the reversible conversion reactions between PbO 2 and Pb. This work perfectly confirms that Pb 3 Nb 4 O 13 nanowires might be a potential anode material for LIBs, SIBs and PIBs. [ABSTRACT FROM AUTHOR]

To fulfill the requirement for large-scale energy-storage systems, lithium ions batteries have been attracted great attentions. It is necessary to develop the anode material with high rate capability, long cycling life and outstanding safety. Here, N-doped carbon been successfully synthesized and estimated as an anode material for lithium ions batteries. PbLi 2 Ti 6 O 14 is isostructural with SrLi 2 Ti 6 O 14 . After nitrogen-doped carbon coating, PbLi 2 Ti 6 O 14 @NC delivers a high capacity of 143.2 mAh g −1 at a current density of 100 mA g −1 and remains 104.8 mAh g −1 even at 700 mA g −1 . In addition, PbLi 2 Ti 6 O 14 @NC also possesses excellent cyclic stability. The reversible capacity of PbLi 2 Ti 6 O 14 @NC can keep at 99.7 mAh g −1 after 1500 cycles. Such results are also proved by CV tests and EIS measurements. Meanwhile, the lithium storage mechanism of PbLi 2 Ti 6 O 14 @NC is investigated by an in situ XRD technique. It indicates that PbLi 2 Ti 6 O 14 @NC has a stable structural host. These aforementioned results suggest that PbLi 2 Ti 6 O 14 @NC has great potential working as an anode material for lithium ions batteries. [ABSTRACT FROM AUTHOR]

Nanostructures always have an advantage in electrochemical research. In this work, the GeNb 18 O 47 nanowires are synthesized by an easy electrospinning method for the first time. We study morphologies and electrochemical properties of as-obtained GeNb 18 O 47 nanowires via the X-ray diffraction, charge/discharge curve, cyclic voltammetry, scanning electron microscopy and transmission electron microscopy. As expected, GeNb 18 O 47 nanowires exhibit impressive charge capacity of 216.9 mAh g −1 at a current density of 100 mA g −1 and high-capacity retention of 93.6% after 200 cycles. Electrochemical analyses show that GeNb 18 O 47 nanowires exhibit the lower redox polarization, smaller charge transfer resistance and higher Li + diffusion coefficient compared with sol-gel formed bulk sample. Therefore, the GeNb 18 O 47 nanowire is a promising active electrode material for the lithium batteries. [ABSTRACT FROM AUTHOR]