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Novel battery architectures with improved safety, power and energy density are currently being demanded for battery miniaturization. We present a rechargeable full cell fabricated with self-organized titania nanotubes (nt-TiO 2 ) and self-organized LiNi 0.5 Mn 1.5 O 4 nanowires (LNMO). The effects of the Li 3 PO 4 -coated nt-TiO 2 on the electrochemical performance of the full cell are studied. A complete (de)-intercalation of lithium into both electrodes is observed, and cells avoid the use of metallic lithium while displaying improved safety and restrained lowering of the overall cell voltage. The surface modified electrodes exhibit better rate capability and cycling performance compared to non-treated electrodes. The nt-TiO 2 , Li 3 PO 4 /EC:DEC LiPF 6 /LiNi 0.5 Mn 1.5 O 4 cell could be cycled at 5C rate, with associated capacity of 125 mA h g −1 , energy density of 325 W h kg −1 and power density of 637 μW cm −2 μm −1 . These results give evidence to the compatibility between both nanostructured electrodes particularly when lithium phosphate exerts a stabilization effect at the electrode/electrolyte interface, facilitating improved mass transfer and Li-diffusion at high rates. [ABSTRACT FROM AUTHOR]

Sodium-deficient nickel-manganese oxides exhibit a layered structure, which is flexible enough to acquire different layer stacking. The effect of layer stacking on the intercalation properties of P3-Na xNi0.5Mn0.5O2 ( x=0.50, 0.67) and P2-Na2/3Ni1/3Mn2/3O2, for use as cathodes in sodium- and lithium-ion batteries, is examined. For P3-Na0.67Ni0.5Mn0.5O2, a large trigonal superstructure with 2√3 a×2√3 a×2 c is observed, whereas for P2-Na2/3Ni1/3Mn2/3O2 there is a superstructure with reduced lattice parameters. In sodium cells, P3 and P2 phases intercalate sodium reversibly at a well-expressed voltage plateau. Preservation of the P3-type structure during sodium intercalation determines improving cycling stability of the P3 phase within an extended potential range, in comparison with that for the P2 phase, for which a P2- O2 phase transformation has been found. Between 2.0 and 4.0 V, P3 and P2 phases display an excellent rate capability. In lithium cells, the P3 phase intercalates lithium, accompanied by a P3- O3 structural transformation. The in situ generated O3 phase, containing lithium and sodium simultaneously, determines the specific voltage profile of P3-Na xNi0.5Mn0.5O2. The P2 phase does not display any reversible lithium intercalation. The P3 phase demonstrates a higher capacity at lower rates in lithium cells, whereas in sodium cells P3-Na xNi0.5Mn0.5O2 operates better at higher rates. These findings reveal the unique ability of sodium-deficient nickel-manganese oxides with a P3-type structure for application as low-cost electrode materials in both sodium- and lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A nanocomposite of sodium titanate/titania nanotrees self-organized in a parallel fashion to form nanoforests is successfully prepared and used as high-performance anode for Na-ion microbatteries. The first step of the synthesis is the anodic oxidation of Ti foils to form self-organized amorphous TiO 2 nanotubes followed by insertion of sodium in aqueous media at room temperature. Then the composite is thermally dehydrated and crystallized as monoclinic Na 2 Ti 6 O 13 /rutile nanotrees. EPR spectra evidence a significant increase in Ti 3+ content during sodium/proton insertion and a decrease on heating. SEM images reveal that while the height of the nanotubes is similar to the nanoforest (c.a. 8.0 μm) the morphology changes from aligned nanotubes to nanotrees of complex texture. The electrochemical results of sodium test cells in non-aqueous electrolyte using the Na 2 Ti 6 O 13 /TiO 2 nanocomposite electrodes show flat profiles of sodium insertion and de-insertion at 0.7 and 0.9 V, respectively. The observed reversible capacity of 130 μA h cm −2 over 150 cycles is almost threefold the value of titania nanotubes annealed at a same temperature. Both characteristics are of great interest to achieve safe and efficient Na-ion microbatteries. [ABSTRACT FROM AUTHOR]

This work aims to maximize the number of active sites for energy storage per geometric area, by approaching the investigation to 3D design for microelectrode arrays. Self-organized Li 4 Ti 5 O 12 /TiO 2 /Li 3 PO 4 composite nanoforest layer (LTL) is obtained from a layer of self organized TiO 2 /Li 3 PO 4 nanotubes. The electrochemical response of this thin film electrode prepared at 700 °C exhibited lithium insertion and de-insertion at 1.55 and 1.57 V respectively, which is the typical potential found for lithium titanates. The effects of lithium phosphate on lithium titanate are explored for the first time. By cycling between 2.7 and 0.75 V the LTL/LiFePO 4 full cell delivered 145 mA h g − 1 at an average potential of 1.85 V leading to an energy density of 260 W h kg − 1 at C/2. Raman spectroscopy revealed that the γ-Li 3 PO 4 /lithium titanate structure is preserved after prolonged cycling. This means that Li 3 PO 4 plays an important role for enhancing the electronic conductivity and lithium ion diffusion. [ABSTRACT FROM AUTHOR]

A 3D mesoporous TiO 2 material with well-developed mesostructure is prepared in the form of a binder-free thin (100 nm) film and studied as potential candidate for the negative electrode in lithium microbatteries. By appropriate thermal treatments, the selected crystal structure (anatase, rutile, or amorphous), and micro-/mesostructure of the materials was obtained. The effects of voltage window and prelithiation treatment improved first cycle reversibility up to 86% and capacity retention of 90% over 100 cycles. After a prolonged intercalation of lithium ions in ordered mesoporous TiO 2 appeared small particles assigned to Li 2 Ti 2 O 4 with cubic structure as observed from ex-situ TEM micrographs. This study highlights the flexibility of the potential window to which the electrode can operate. Maximum capacity values over 100 cycles of 470 μA h cm −2 μm −1 and 177 μA h cm −2 μm −1 are obtained for voltage ranges of 0.1–2.6 V and 1.0–2.6 V, respectively. The observed values are between 6 and 2 times higher than those obtained for films with 600 nm (80 μA h cm −2 μm −1 ) and 900 nm (92 μA h cm −2 μm −1 ) lengths. This indicates that 100 nm thin TiO 2 films with high accessibility show finite-length type diffusion which is interesting for this particular application. [ABSTRACT FROM AUTHOR]

Li1.2+xTi1.9−xFexCa0.1(PO4)3 (x=0.1–0.4) compounds were synthesized by a sol–gel method and studied by X-ray diffraction, SEM and 57Fe Mössbauer spectroscopy. The rhombohedral (R c) phase prevailed for all studied samples, while for x≥0.3 an orthorhombic Pbca phase appeared. The substitution of Ti4+ by Fe3+ and Ca2+ led to an increase of the unit cell parameters of the rhombohedral phase. The hyperfine 57Fe Mössbauer parameters showed a single signal ascribable to Fe3+ in an anisotropic distribution of charges surrounding the probe atom. The double substitution of Ti4+ by Fe3+ and Ca2+ in Li1.2+xTi1.9−xFexCa0.1(PO4)3 resulted in a net improvement of the ionic conductivity, as compared to pristine LiTi2(PO4)3. Ionic conductivities of 3.3·10−4 Scm−1 and 2.4·10−5 Scm−1 at room temperature, and 5.23·10−4 Scm−1 and 8.44·10−5 Scm−1 at 373K were observed for Li1.3Ti1.8Fe0.1Ca0.1(PO4)3 and Li1.6Ti1.5Fe0.4Ca0.1(PO4)3, respectively. [ABSTRACT FROM AUTHOR]

Solid electrolytes are crucial in the development of advanced lithium batteries and related technologies. Orthorhombic Li2NaPO4 (nalipoite) was synthesized, and its ionic conductivity compared very favorably with that of Li3PO4. The potential applicability of Li3-xNaxPO4 as a lithium ion solid electrolyte was investigated for first time. First-principles DFT calculations were used to evaluate the possibilities of preparing other crystal structures. [ABSTRACT FROM AUTHOR]

Highlights: [•] Cu–Sn nanowires with 80–100nm diameter and 2μm length are made by electrodeposition. [•] A stable areal capacity of 70μAhcm− 2 over 100 cycles is obtained for η′-Cu5Sn6 phase. [•] The nanowire morphology minimizes volume variations of Sn–Li alloys. [•] The conductive Cu matrix facilitates electrical contact and cycling stability. [Copyright &y& Elsevier]

Abstract: A thin film electrode consisting of a mixture of iron and nickel oxides is prepared by a single route. Electrochemical deposition from Fe2+ and Ni2+ solutions on a titanium substrate and further thermal treatment at low temperature allowed obtaining a nanocomposite thin film of NiO and Fe2O3. The electrochemical studies performed on lithium cells assembled with this electrode material revealed the smallest irreversibility from first to second discharge ever reported during the conversion reactions of metal oxides at ∼0.8 V. Unlike bulk transition metal oxides, the poorly-crystalline oxidized material exhibited an unusually low discharge polarization. The 57Fe Mössbauer spectra of partially discharged and charged electrodes evidenced the reversibility of the conversion reaction with lithium and the efficiency of the recovery of the local environment of iron after the first cycle. [Copyright &y& Elsevier]

Cathode materials with the generalstoichiometry Li1.2+xTi1.9–xFexCa0.1(PO4)3(0 ≤ x≤ 0.4)and Li1+2xTi2–xCax(PO4)3(0.1 ≤ x≤ 0.5) were prepared bya sol–gel methodfollowed by annealing at 750 °C in Ar. These samples were investigatedby powder X-ray diffraction analysis, electron paramagnetic resonanceand 59Fe Mössbauer spectroscopy, scanning electronmicroscopy micrographs, and electrochemical lithium intercalation.The NASICON-type structure belongs to the R3̅cspace group. Upon substitution of Ti4+, the c/aratio and cell volume increased asa result of the higher ionic radii of Ca2+(1.14 Å),Fe2+(0.92 Å), and Fe3+(0.785 Å)compared to those for Ti4+(0.745 Å). Although calciumis not electroactive versus lithium, the electrochemical Li insertionwas significantly affected by the presence of calcium ions in theNASICON-type structure. The determination of oxidation state of titaniumions in Ca-substituted orthophosphates showed that tetrahedrally coordinatedTi3+ions in the Li-rich end composition participate inthe electrochemical reaction of intercalation of Li+shiftingthe potential of reaction from 2.5 to 2.8 V in charge. The role ofiron is elucidated with the use of 57Fe Mössbauerspectroscopy. The Fe2+observed in the as-prepared electrodeis completely oxidized to Fe3+in the first charge. Successivedischarge/charge of lithium test cells evidenced the involvement ofthe whole iron content in the reaction undergoing at 2.8 V. Stablecapacities ranging between 126 and 131 mA·h/g after 100 cyclesand about 120 mA·h/g after 60 cycles are recorded for Li1.2+xTi1.9–xFexCa0.1(PO4)3(x= 0.1–0.4) and Li1+2xTi2–xCax(PO4)3based electrodes (x= 0.1–0.5), respectively. [ABSTRACT FROM AUTHOR]

Abstract: Electrochemical deposition from Ni2+ and Fe2+ using sulfate and nitrate solutions is carried out under galvanostatic regime. The resulting films are oxidized and examined in lithium test cells as potential anode materials for lithium-ion batteries. X-ray diffraction, XPS and SAED–TEM analyses revealed a thin film based on nanocomposite NiO and Fe2O3. Cycling studies show the smallest discharge polarization ever reported during the conversion reactions of metal oxides at ∼0.8V. Unlike typical transition metal oxides, the amorphous oxidized material exhibited low irreversibility from first to second discharge (∼15%) and a distinctive plateau on consecutive discharge branches. The changes in the film thickness on increasing deposition time and the crystallization phenomena on annealing the deposits strongly affect the electrochemical behavior. The present approach allows preparing a powder free electrode with improved coulombic efficiency directly on the current collector and opens a set of novel preparation routes in this field with intriguing results. [Copyright &y& Elsevier]

Abstract: Oxidised FeCoNi alloys are prepared by an electrodeposition-annealing method. The performances of this type of nanostructured electrode are studied by the combination of structural techniques (transmission electron microscopy and X-ray diffraction) and electrochemical tests in lithium cells. The oxidised FeCoNi alloy achieves an excellent Coulombic efficiency in first cycle (85–90%) as well as a minimal discharge polarization on subsequent cycles because the voltage plateau ascribable to metal reduction is kept invariable at around 0.8V. These results disclose new pathways to fabricate low-cost and high-performance conversion electrodes as anode material for Li-ion secondary batteries. [Copyright &y& Elsevier]

Abstract: The use of self-organized TiO2 nanotube arrays electrochemically grown onto Si is investigated for the fabrication of an alternative electrode dedicated to on-chip Li-ion 2D microbatteries. Discharge/charge curves and cycling performance are studied in lithium-anode electrochemical test cells for both amorphous and crystalline titania nanotubes. At 5μAcm−2 amorphous TiO2 nanotube layers onto Si deliver a maximum areal capacity of 89μAhcm−2 in the first reversible discharge and 56μAhcm−2 over 50 cycles. We demonstrate that these nanostructured thin film electrodes showing such electrochemical performances are compatible with IC technology. [Copyright &y& Elsevier]

Abstract: The electrochemical reaction of Co2SnO4 with Li is studied by using ex-situ 119Sn Mössbauer spectroscopy. During the progress of the first discharge process between 3 and 0V, the relative intensity of the signal originated from Sn(IV) atoms continuously decreases. A new signal which is attributed to cobalt–tin intermetallic compounds emerges, and the relative intensity of this signal increases between 3 and 0V. At around 0V, the signal corresponding to Sn(IV) atoms is not observed, while a lithium-rich tin phase appears. After charging up to 3V, the tin atoms are re-oxidized and Sn(IV) ions are formed. Reversible capacities over 800mAhg−1 are achieved in the first cycles. cobalt–tin compounds are promising negative electrodes for lithium-ion batteries. [Copyright &y& Elsevier]

Abstract: The layered particles of lithium cobalt oxide (LiCoO2) have been modified using rotor blade grinding, re-annealing, and a combination of both treatments. SEM, XPS and EIS were used to study the effects of these treatments on the LiCoO2 particles, and changes in electrochemical behaviour in the 4-V region vs. Li+/Li were explored. After short grinding times (20min), primary layered particles formed larger aggregates and poor electrochemical behaviour was observed. After 60min grinding, LiCoO2 showed a net improvement in reversible specific capacity and capacity retention, which is due to the formation of ultrafine layered particles. Further grinding up to 180min lead to surface carbonation, increased impedances and poor electrochemical performance. Re-annealing improved the electrochemical behaviour of both ground and unground LiCoO2. The best electrochemical behaviour was observed after grinding for 60min and then re-annealing at 850°C, which is linked with a low charge transfer resistance. XPS measurements revealed that the particles surface remained unchanged after heating to 500°C, while heating to 850°C eliminated surface carbonates, and prolonged grinding yielded extended surface carbonation. [Copyright &y& Elsevier]

Magnesium batteries are a promising technology for a new generation of energy storage for portable devices. Attention should be paid to electrolyte and electrode material development in order to develop rechargeable Mg batteries. In this study, we report the use of the spinel lithium titanate or Li4Ti5O12 (LTO) as an active electrode for Mg2+-ion batteries. The theoretical capacity of LTO is 175 mA h g−1, which is equivalent to an insertion reaction with 1.5 Mg2+ ions. The ability to enhance the specific capacity of LTO is of practical importance. We have observed that it is possible to increase the capacity up to 290 mA h g−1 in first discharge, which corresponds to the reaction with 2.5 Mg2+ ions. The addition of MgCl2·6H2O to the electrolyte solutions significantly improves their electrochemical performance and enables reversible Mg deposition. Ex-situ X-ray diffraction (XRD) patterns reveal little structural changes, while X-ray photoelectron spectrometer (XPS) (XPS) measurements suggest Mg reacts with LTO. The Ti3+/Ti4+ ratio increases with the amount of inserted magnesium. The impedance spectra show the presence of a semicircle at medium-low frequencies, ascribable to Mg2+ ion diffusion between the surface film and LTO. Further experimental improvements with exhaustive control of electrodes and electrolytes are necessary to develop the Mg battery with practical application. [ABSTRACT FROM AUTHOR]

The recent introduction of glyme-based solvents has opened new opportunities to characterize graphitic materials as anodes for sodium-ion batteries. We evaluated the electrochemical behaviour of a graphitized carbon nanofiber for the first time. X-ray diffraction, electron paramagnetic resonance and nuclear magnetic resonance allowed the sodium insertion mechanism to be untangled, in which the occurrence of an activation process during the first discharge enhances sodium accessibility to active redox centres at the interlayer space. Morphological changes observed by electron microscopy could be responsible for this behaviour. A fully graphitized carbon nanofibers/NaPF6(diglyme)/Na3V2(PO4)3 sodium-ion battery was tested to probe the reliability of this graphitic nanostructure as a negative electrode. [ABSTRACT FROM AUTHOR]

Abstract The promising application of Na-ion batteries in large-scale energy storage such as smart grid has encouraged intensive research on Na-based insertion compounds and their implementation in full Na-ion cells. Herein, the electrochemical performance of half cells using Na 0.66 Ni 0.33˗x Zn x Mn 0.67 O 2 (x = 0, 0.07 and 0.14) cathodes in diglyme-based electrolyte are first studied. For x = 0.07, high discharge capacities of 120 and 80 mA h g−1 at 15 and 150 mA g−1, respectively are measured, with stable operation voltage exceeding 4.0 V vs. Na+/Na and cycling life over 200 cycles. Moreover, DSC results of the charged positive electrodes confirmed that the thermal stability was improved distinctively by zinc modification. Also, graphitized petroleum coke exhibits good performance in diglyme-based electrolyte in terms of stable capacity (100 mA h g-1) over 200 cycles in a stable plateau within 0.5–1.0 V vs. Na+/Na. Thereafter, a full Na-ion battery using Na 0.66 Ni 0.26 Zn 0.07 Mn 0.67 O 2 cathode, diglyme electrolyte, and petroleum coke anode is proposed here that shows impressive performances, i.e. shows high discharge capacity of 86 mA h g-1 and 85% retention after 155 cycles. It is believed that diglyme-based electrolytes should be readily extended to other layered sodium oxide electrodes and their full cells. Graphical abstract Image 1 Highlights • A novel application of diglyme-based electrolyte for layered sodium oxide cathodes. • Comparable electrochemical performances to PC-based electrolyte were observed. • Na-ion full cells are built with Na 0.66 Ni 0.33˗x Zn x Mn 0.67 O 2 and petroleum coke. • Full cells show high energy density (258 W h kg-1) and electrochemical stability. [ABSTRACT FROM AUTHOR]

P3-NaxNi0.5Mn0.5O2 (x = 0.50, 0.67) and P2-Na0.66Ni0.33Mn0.66O2 are prepared by thermal decomposition of freeze-dried Na, Ni, and Mn acetate precursors in O2 at 400 °C followed by annealing in air (700 °C, 24 h). [ABSTRACT FROM AUTHOR]

Orthorhombic Li2NaPO4 is synthesized by stirring aqueous solutions of LiOH, NaOH, and H3PO4 followed by drying at 700 °C in air overnight. [ABSTRACT FROM AUTHOR]

Off-stoichiometric Na3+3 xV2− x(PO4)3 samples have been prepared by a sol-gel route. X-ray diffraction and XPS revealed the flexibility of the NASICON framework to accommodate these deviations of the stoichiometry; at least for low x values. X-ray photoelectron spectra evidenced the presence of Na4P2O7 impurities. The synergic combination of the structural deviations and the presence of Na4P2O7 impurities induce a significant improvement of the electrochemical performance and cycling stability at high rates, as compared to the stoichiometric Na3V2(PO4)3 sample. The fast kinetic response provided by the induced off-stoichiometry involves a decrease of the cell resistance. [ABSTRACT FROM AUTHOR]

A novel design of a sodium-ion cell is proposed based on the use of nanocrystalline thin films composed of transition metal oxides. X-ray diffraction, Raman spectroscopy and electron microscopy were helpful techniques to unveil the microstructural properties of the pristine nanostructured electrodes. Thus, Raman spectroscopy revealed the presence of amorphous NiO, α-Fe2O3 (hematite) and γ-Fe2O3 (maghemite). Also, this technique allowed the calculation of an average particle size of 23.4 Å in the amorphous carbon phase in situ generated on the positive electrode. The full sodium-ion cell performed with a reversible capacity of 100 mA h g−1 at C/2 with an output voltage of about 1.8 V, corresponding to a specific energy density of about 180 W h kg−1. These promising electrochemical performances allow these transition metal thin films obtained by electrochemical deposition to be envisaged as serious competitors for future negative electrodes in sodium-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: The preparation of thin films of x Fe2O3–(1−x) NiO (x=0.38–0.49) is reported. A single two-step process including metal electrodeposition and thermal oxidation was performed. The nanocrystalline character of the electrode material was evidenced by X-Ray diffraction and electron microscopy. The electrochemical properties of sodium batteries assembled with these electrode materials were studied for the first time. The synergic effects of both transition metal elements along with the nano-crystalline character are responsible for the good electrochemical performance. The coulombic efficiency of sodium cell improved drastically up to 68%. The post-mortem analysis of discharged and charged electrodes by 57Fe Mössbauer spectroscopy allowed determining the redox mechanism on the probe atom during the first cycle. [Copyright &y& Elsevier]

The use of iron-, tin- and antimony-containing carbon fibres as potential candidates for the negatives electrode of advanced lithium-ion batteries is described. Two different types of fibres are used: non-graphitic and partially graphitized carbon. EPR results show that both carbon and dispersed iron participate in redox processes during the electrochemical reaction with Li. Lithium test cells evidence higher capacities for partially graphitized fibres. The addition of dispersed tin or antimony is used to improve the capacity of the non-graphitic fibres by formation of lithium-tin and lithium-antimony compounds. Reversible capacity values close to 300 mA h g-1 are achieved in both partially graphitized and composite electrodes containing Li-alloying elements. The use of nanodispersed transition metals, i.e. iron, in a carbon matrix is proposed here as an alternative to carbon composites containing Li-alloying elements. [Copyright &y& Elsevier]

A graphitized coke material obtained from petroleum residua was mechanically ground at different milling times between 0 and 100 h. Electrochemical reactions with both lithium and sodium are significantly altered as a function of grinding time. Short-time ball milling of graphite (1 and 5 h) induces a limited decrease in particle size and an increase in microstrain content. Simultaneously, alkali metal intercalation and electrolyte decomposition are hindered, and thus the irreversible and reversible capacities decrease. For longer milling time (up to 100 h), average crystallite size decreases and particles adopt a lamellar shape. Simultaneously, the irreversible capacity increases and correlates with an increase of the resistance, as obtained by impedance spectroscopy. Ex-situ XRD shows that extensively ground graphite samples need a higher discharge specific capacity to reach the formation of n-stages as compared to non-ground graphite, this being indicative of lithium incorporation in energetically different sites to the interlayer space. Sodium storage capacity increases with prolonged grinding time. This effect is shown here for the first time for graphitized cokes. [Copyright &y& Elsevier]

Sodium-ion batteries are considered a promising alternative to lithium-ion batteries due to its low cost and potential applications for large-scale energy storage. In this work, we focus on improving the Na-ion storage electrochemical performance of TiO 2 anodes by using diglyme-based electrolyte solutions. Significantly better performances are observed for the first time in diglyme-based electrolyte solution, as compared to conventional carbonate electrolyte solutions with and without additives such as fluoroethylene carbonate (FEC) and vinylene (VC). The best TiO 2 electrode demonstrated a high specific capacity of 248 mA h g−1 at 25 mA g−1 current density, ∼100% coulombic efficiency, superior pseudocapacitive Na-ion storage, and good capacity retention on extended galvanostatic charge-discharge cycles. A full-cell assembled with TiO 2 anode, Na 3 V 2 (PO 4) 3 cathode and NaPF 6 -diglyme electrolyte solution demonstrated an energy density as high as 440 W h kg−1. Superior electrochemical performance of TiO 2 anodes in diglyme-based electrolyte is credited to the enhanced passivation and Na-ion conducting properties of polyether-based solid electrolyte interfaces (SEI) compared to polycarbonate-based counterparts. Carbon coating also resulted in the reduced decomposition of both diglyme and carbonate based electrolyte solutions. These results potentially encourage the use of ether-based electrolyte solutions for further improving the electrochemical performance and commercialization of rechargeable Na-ion batteries. Image 1 • Novel application of diglyme-based electrolyte for TiO 2 and C@TiO 2 nanosheets. • Enhanced electrochemical performance in diglyme as compared to carbonate-based ones. • Na-ion full cells are built with C@TiO 2 , diglyme and Na 3 V 2 (PO 4) 3. • Full cells show high energy density (440 W h kg−1) and electrochemical stability. [ABSTRACT FROM AUTHOR]

This study reports on the electrochemical alloying-dealloying properties of Mg2Sn intermetallic compounds. 119Sn Mössbauer spectra of β-Sn powder, thermally alloyed cubic-Mg2Sn, and an intermediate MgSn nominal composition are used as references. The discharge of a Mg/micro-Sn half-cell led to significant changes in the spectra line shape, which is explained by a multiphase mechanism involving the coexistence of c-Mg2Sn, distorted Mg2-δSn, and Mg-doped β-Sn. Capacities and capacity retention were improved by using nanoparticulate tin electrodes. This material reduces significantly the diffusion lengths for magnesium and contains surface SnO and SnO2, which are partially electroactive. The half-cell potentials were suitable to be combined versus the MgMn2O4 cathodes. Energy density and cycling properties of the resulting full Mg-ion cells are also scrutinized. [ABSTRACT FROM AUTHOR]

Although the LiNi 0.5 Mn 0.25 Co 0.25 O 2 holds the merits of high theoretical capacities and a relatively high operating voltage, the battery performance suffers from the severe cycling decay due to the unstable solid electrolyte interface on the cathode. Herein, we present LiPO 2 F 2 as a salt-type electrolyte additive to enhance the cycling stability of large-size crystallite LiNi 0.5 Mn 0.25 Co 0.25 O 2 cathodes. Results demonstrate that 1 wt% LiPO 2 F 2 can significantly improve not only the initial coulombic efficiency by 3%, but also the cycling stability and rate capability at 25 °C. Furthermore, the discharge capacity of LiNi 0.5 Mn 0.25 Co 0.25 O 2 cathodes still maintain 156 mAh g −1 after 100 cycles even when the temperature increases to 55 °C. In-depth experimental characterization and theoretical calculation indicate that a new stable and thin (e.g. 15–20 nm) film formed on the surface of the cathodes, with composition of LiPO 2 F 2 , LiF, etc., which significantly reduces charge transfer impedance of the electrodes, and therefore significantly improves the cycling and rate performance of LiNi 0.5 Mn 0.25 Co 0.25 O 2 . [ABSTRACT FROM AUTHOR]

Converting ‘trash’ waste residua to active functional materials ‘treasure’ with high added value is being regarded as a promising way to achieve the sustainable energy demands. Carbonaceous materials cannot insert sodium except when graphite co-intercalates solvents such as diglyme. Here, we show that petroleum coke and shale coke annealed at different temperatures can also insert sodium by reversible intercalation phenomena in a diglyme-based electrolyte. The structural and morphological studies will reveal significant differences justifying their distinct electrochemical behavior. Galvanostatic tests exhibit a flat plateau at about 0.7 V ascribable to the reversible reaction. At the end of the discharge, a Stage-I ternary intercalation compound is detected. Two diglyme molecules are co-intercalated per alkali ion, as evidenced by 1-D Patterson diagrams, FTIR and TGA analyses. The full sodium-ion cell made with P-2500/NaPF 6 (diglyme)/Na 3 V 2 (PO 4 ) 3 delivered an initial reversible capacity of 75 mA h g −1 at C rate and an average potential of 2.7 V. Thus, the full cell provides an energy density of 202 W h kg −1 . This sodium-ion system can be considered a promising power source that encourages the potential use of low-cost energy storage systems. [ABSTRACT FROM AUTHOR]

This work aims to valorize the shrimp wastes as a template for obtaining nanoparticulate tin battery electrodes. Using shrimp waste skins is possible to get a network material made of nanominerals (NMN) with elements such as Ca, Mg, Na, and Al and containing a rich source of nitrogen. Three different electrode materials prepared under different conditions validated this study. Shrimp wastes (SW), SW-tin prepared at room temperature (ST-RT) and SW-tin prepared by carbothermal reduction (ST-CT) are studied. 119Sn Mössbauer spectroscopy determined the atomic fraction is 59.5 and 40.5% of SnO 2 and β-Sn co-existing in the ST-CT sample. SEM and TEM micrographs confirmed a particle size of 2–5 nm of tin-based materials homogeneously distributed on the NMN matrix. Electrochemical investigation in Na-half cells demonstrated superior electrochemical performance of ST-CT with 162 mA h g−1 reversible capacity which can be retained at 60% over 200 cycles under different rates (C/10 to 2 C). The SW and ST-RT displayed the worse reversible capacities. Eventually, a Na-ion full cell is assembled versus Na 3 V 2 (PO 4) 3 showing good properties in terms of energy density. [Display omitted] • We use shrimp/tin waste (STW) material, which has never been tested for energy storage. • Advanced storage properties in Na-ion full cells are proposed for first time using natural sources. • Na-half cells shows a 162 mA h g−1 of reversible capacity retained 60% over 200 cycles. • Combined with NVP cathode, it exhibits average cell potential of 2.5 V reaching 310 W h kg−1. [ABSTRACT FROM AUTHOR]

• So-called hybrid concepts boosted the voltage of MgMnSiO 4 cathode vs. metallic mg. • The electrolyte is an electrochemically active part with transmitter of Mg2+/H+. • Mg/Mg(TFSI) 2 -DME+W04/MgMnSiO 4 safe battery with 300 W h kg−1 energy density. • Acceptable time-dependent stability of the electrolyte determined by 25Mg NMR. MgMnSiO 4 is a promising cathode material for rechargeable magnesium batteries, however, it still suffers from unsatisfactory electrochemical performances. Although the modulation of electrolyte formulation and cell configuration are critical to enhancing the electrochemical behavior of MgMnSiO 4 , few works focused on these important issues. Therefore, to get cathode materials operating at high voltage and overcome the electrostatics problems of bivalent Mg2+ ion, we adopt an unconventional approach of engaging water in a conventional nonaqueous solution such as 0.5 M Mg(TFSI) 2 in DME (dimethoxyethane). The electrochemical reaction of Mg/electrolyte/C@MgMnSiO 4 cell occurs at 2.8 – 0.5 V (vs. Mg2+/Mg) with 160 mA h g-1 entailing 300 W h kg−1 at the materials' level. The results show that C@MgMnSiO 4 could be a potential cathode material for high-energy magnesium secondary batteries in a bifunctional electrolytes, which not just utilized as a transmitter... of Mg2+, but also as a source of H+. We prove that the generated H+ increases the isotropy around Mg2+, changes in the Mn oxidation states, and modifies Mg/MgO interphase. Eventually, by assembling several Mg-ion full cells versus different anodes including Li 4 Ti 5 O 12 , activated carbon, and Mg 0.5 MnSiO 4 , we recall the main challenges to overcome. [ABSTRACT FROM AUTHOR]

Titania nanotubes (nt-TiO2) with high aspect ratio and amorphous character were prepared by Ti anodization at high voltage (100 V). After annealing, the nanotubes crystallized to anatase phase and the XRD patterns and TEM images showed that self-organized anatase nt-TiO2 are composed of crystallographically oriented nanocrystalline domains on the Ti substrate. The contribution of faradic and pseudocapacitive processes was studied for anatase nt-TiO2 in Na cells obtaining the b-parameter values from cyclic voltammetry experiments. The reaction between anatase nt-TiO2 and Na is dominated by redox surface processes (pseudocapacitance) in the region over ca. 0.5 V and by irreversible faradic processes below ca. 0.3 V. The cycling performance of anatase nt-TiO2 in sodium cell was very strongly affected by the imposed electrochemical conditions. Reversible capacity values of about 150-200 mA h g-1 and good cycling behaviour were found for 2.6-0.5 V of potential limits. Impedance spectra and 23Na MAS NMR spectra were also used to study the reaction mechanisms. In addition, it was found that by using variable voltage during the anodization of titanium, the resulting electrode exhibits excellent cycling behaviour (ca. 190 mA h g-1 after ca. 800 cycles). These results are the best cycling behaviour reported to date for anatase in the form of self-organized nanotubes for sodium ion microbatteries. [ABSTRACT FROM AUTHOR]

Abstract: Heterostructures composed of reduced graphene oxide and self-organized titania nanotubes (nt-TiO2) are examined as novel electrode material for lithium-ion batteries. The novelty here resides in the deposition of a graphene-like film on self-organized nanotubes and that, as compared with previous materials, the differences in behavior are significant as the heterostructure combines previously reported advantages of self-organized nt-TiO2 with those emerging from the graphene composites. The preparation of this nt-TiO2/graphene hybrid electrode material is described here. The deposition of a graphene film on self-arranged amorphous nt-TiO2 was confirmed by using SEM, Raman spectroscopy and mapping of composition. Lithium test cells display capacities that can exceed 300 mAh g−1 over 100 cycles and that are therefore superior to those of bare nt-TiO2 and anatase or rutile TiO2–graphene hybrid nanostructures. The excellent rate performance of these electrodes makes charge–discharge possible up to at least 300 C-rate. The impedance spectra show that the graphene-like film improves the interface properties in the hybrid electrode. In addition to the environmentally friendly nature of the active electrode material, the moderate working voltage offers an important safety advantage in that it protects the battery from the electroplating phenomena. [Copyright &y& Elsevier]

Amorphous Co–Sn alloy was co-electroplated on a three-dimensional framework of nickel foam and then CoSn2 phase was formed after annealing at 200 °C. It is observed that short electrodeposition times favour a higher x-value in the resulting CoSnx alloy. Low current densities and short electrodeposition times favour the formation of discrete submicrometric particles (Volmer–Weber model). The morphology of the electrode allows achieving high areal and gravimetric capacity values under high rates of charge–discharge in Li cells. The observed areal capacity values are in the range between 0.2 and 6 mAh cm−2, depending on the cycling rate and the mass of electrodeposited alloy. For electrodes with short electrodeposition time and Volmer–Weber model, the response to high charge–discharge rates is excellent and the gravimetric capacity is around 800 mAh g−1. [ABSTRACT FROM AUTHOR]

Lithium metal batteries have achieved large-scale application, but still have limitations such as poor safety performance and high cost, and limited lithium resources limit the production of lithium batteries. The construction of these devices is also hampered by limited lithium supplies. Therefore, it is particularly important to find alternative metals for lithium replacement. Sodium has the properties of rich in content, low cost and ability to provide high voltage, which makes it an ideal substitute for lithium. Sulfur-based materials have attributes of high energy density, high theoretical specific capacity and are easily oxidized. They may be used as cathodes matched with sodium anodes to form a sodium-sulfur battery. Traditional sodium-sulfur batteries are used at a temperature of about 300 °C. In order to solve problems associated with flammability, explosiveness and energy loss caused by high-temperature use conditions, most research is now focused on the development of room temperature sodium-sulfur batteries. Regardless of safety performance or energy storage performance, room temperature sodium-sulfur batteries have great potential as next-generation secondary batteries. This article summarizes the working principle and existing problems for room temperature sodium-sulfur battery, and summarizes the methods necessary to solve key scientific problems to improve the comprehensive energy storage performance of sodium-sulfur battery from four aspects: cathode, anode, electrolyte and separator. [ABSTRACT FROM AUTHOR]

The development of low-cost electrode devices from conductive materials has recently attracted considerable attention as a sustainable means to replace the existing commercially available electrodes. In this study, two different electrode surfaces (surfaces 1 and 2, denoted as S1 and S2) were fabricated from chocolate wrapping aluminum foils. Energy dispersive X-Ray (EDX) and field emission scanning electron microscopy (FESEM) were used to investigate the elemental composition and surface morphology of the prepared electrodes. Meanwhile, cyclic voltammetry (CV), chronoamperometry, electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) were used to assess the electrical conductivities and the electrochemical activities of the prepared electrodes. It was found that the fabricated electrode strips, particularly the S1 electrode, showed good electrochemical responses and conductivity properties in phosphate buffer (PB) solutions. Interestingly, both of the electrodes can respond to the ruthenium hexamine (Ruhex) redox species. The fundamental results presented from this study indicate that this electrode material can be an inexpensive alternative for the electrode substrate. Overall, our findings indicate that electrodes made from chocolate wrapping materials have promise as electrochemical sensors and can be utilized in various applications. [ABSTRACT FROM AUTHOR]

Despite the fact that a considerable amount of effort has been invested in the development of biosensors for the detection of pesticides, there is still a lack of a simple and low-cost platform that can reliably and sensitively detect their presence in real samples. Herein, an enzyme-based biosensor for the determination of both carbamate and organophosphorus pesticides is presented that is based on acetylcholinesterase (AChE) immobilized on commercially available screen-printed carbon electrodes (SPEs) modified with carbon black (CB), as a means to enhance their conductivity. Most interestingly, two different methodologies to deposit the enzyme onto the sensor surfaces were followed; strikingly different results were obtained depending on the family of pesticides under investigation. Furthermore, and towards the uniform application of the functionalization layer onto the SPEs' surfaces, the laser induced forward transfer (LIFT) technique was employed in conjunction with CB functionalization, which allowed a considerable improvement of the sensor's performance. Under the optimized conditions, the fabricated sensors can effectively detect carbofuran in a linear range from 1.1 × 10−9 to 2.3 × 10−8 mol/L, with a limit of detection equal to 0.6 × 10−9 mol/L and chlorpyrifos in a linear range from 0.7 × 10−9 up to 1.4 × 10−8 mol/L and a limit of detection 0.4 × 10−9 mol/L in buffer. The developed biosensor was also interrogated with olive oil samples, and was able to detect both pesticides at concentrations below 10 ppb, which is the maximum residue limit permitted by the European Food Safety Authority. [ABSTRACT FROM AUTHOR]

Because of the huge demand for energy materials, it is paramount to develop practical, low-cost, and renewable energy systems. Until now, batteries made of green materials have either been costly or of limited use. Herein, this paper reports the pioneer utilization of fish waste, doped with Pd nanoparticles (Pd NPs) by incipient wetness impregnation to form Pd/Fish-Collagen. The Pd/Fish-Collagen was first used as a catalyst to abate benzene, and then utilized as anode material in three different rechargeable battery systems; Li-, Na-, and Mg- ion batteries. XRD patterns confirmed that the Fish-Collagen (CaS and CaCO 3) was amorphous, while the Pd/Fish-Collagen sample exhibited broad peaks assigned to a mixture of Pd and PdO NPs coexisting with the amorphous Fish-Collagen. TEM and HRTEM images confirmed that the Fish-Collagen and the Pd NPs had average particle sizes of about 70 and 5 nm respectively. The electrochemical properties of the Pd/Fish-Collagen as an anode material in Li, Na, and Mg-based cells showed reversible capacities of 270, 120, and 105 mA h g−1, respectively. The CV and ex-situ XRD tests suggested a pseudocapacitance reaction occurred in Li and Na storage, while the Mg-based cells presented a conversion reaction. This new strategy to generate electrodes from renewable sources is cost-effective and with optimization, millions of tons of this remaining waste can find potential applications in such energy storage systems. • Conversion of Fish waste into Collagen in a waste to treasure strategy is reported. • Nanometric Pd/Fish-Collagen particles are used for energy storage. • Li, Na and Mg cells are studied for first time in this paper. • Pseudocapacitive storage is found in Li and Na cells. • The reaction in Mg-based cells started with a conversion type mechanism. [ABSTRACT FROM AUTHOR]

In this study, Li3V2(PO4)3 (LVP) powders are prepared by a solution synthesis method. The effects of two reducing agents on crystal structure and morphology and electrochemical properties are investigated. Preliminary studies on reducing agents such as oxalic acid and citric acid, are used to reduce the vanadium (V) precursor. The oxalic acid-assisted synthesis induces smaller particles (30 nm) compared with the citric acid-assisted synthesis (70 nm). The LVP powders obtained by the oxalic acid exhibit a higher specific capacity (124 mAh g−1 at 1C) and better cycling performance (122 mAh g−1 following 50 cycles at 1C rate) than those for the citric acid. This is due to their higher electronic conductivity caused by carbon coating and downsizing the particles. The charge-discharge plateaus obtained from cyclic voltammetry are in good agreement with galvanostatic cycling profiles. [ABSTRACT FROM AUTHOR]

Realization of multi-electron reactions per transition metal is an effective strategy to increase the energy density of cathode materials, and comprehensively understanding of their underlying mechanism is necessary to further improve the electrochemical performance of the sodium-ion batteries. Here, we investigate and realize multi-electron reactions in NaVOPO 4 , which could deliver very high specific capacity. In addition, we explore its electrochemical mechanism in great detail by a series of advanced techniques, including XANES, in situ SXRD, 23Na, 31P, and 51V solid state NMR. The results demonstrate that V3−δ/V4+/V5+ redox couples can be realized in NaVOPO 4 , and a biphasic transition followed by a monophasic reaction process occurred during discharge process. Finally, the causes of battery failure are analyzed and corresponding strategies to improve electrochemical performance of NaVOPO 4 are discussed. [ABSTRACT FROM AUTHOR]

In this paper, electrical impedance spectroscopy (EIS) was applied to investigate the stability of oil-in-water (O/W) Pickering emulsions prepared with negatively charged silica nanoparticles in combination with a trace amount of redox switchable fluorescent molecules, ferrocene azine (FcA). Electrical impedance values of emulsions obtained at different emulsification speeds were estimated according to the frequency response data with frequencies ranging from 1 MHz to 1 Hz. The equivalent circuit model of toluene-in-water emulsion was established by the resistor (RO/W) and capacitor (CO/W) in parallel connection. Nyquist diagrams for the emulsions prepared by toluene and water were characterized by the formation of one semi-circle. The droplet size distribution is one of the important factors that affect the stability of the emulsion, except for the volume fraction of water and oil, the size of stabilizing particles, etc. The average particle size of the emulsion droplets decreased as the emulsification speed increased, indicating the higher stability of the emulsion. It was found that the fitted impedance value RO/W of the emulsion decreased with decreasing particle size prepared at different emulsification speeds and storage time by performing real-time EIS detection techniques. The results suggested that EIS could be used to characterize the stability of a toluene-in-water emulsion stabilized by FcA modified silica nanoparticles. Moreover, based on the good electrochemical activity of the FcA molecule, the stability of the Pickering emulsion can be modulated by adding oxidant and reductant and detected by EIS in real-time. [ABSTRACT FROM AUTHOR]

Silicon-based anodes are extensively studied as an alternative to graphite for lithium ion batteries. However, silicon particles suffer larges changes in their volume (about 280%) during cycling, which lead to particles cracking and breakage of the solid electrolyte interphase. This process induces continuous irreversible electrolyte decomposition that strongly reduces the battery life. In this research work, different silicon@graphite anodes have been prepared through a facile and scalable ball milling synthesis and have been tested in lithium batteries. The morphology and structure of the different samples have been studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning and transmission electron microscopy. We show how the incorporation of an organic solvent in the synthesis procedure prevents particles agglomeration and leads to a suitable distribution of particles and intimate contact between them. Moreover, the importance of the microstructure of the obtained silicon@graphite electrodes is pointed out. The silicon@graphite anode resulted from the wet ball milling route, which presents capacity values of 850 mA h/g and excellent capacity retention at high current density (≈800 mA h/g at 5 A/g). [ABSTRACT FROM AUTHOR]

In this study, Li4Ti5O12 (LTO) electrodes with different types of water-soluble binders are successfully coated upon aluminum foil. Electrodes containing solely sodium alginate (SA) as a binder or a mixed PVDF/carboxymethyl cellulose (CMC) binder show the most stable performance in 1 M LiPF6 in EC/DMC 1:1 in half cell vs. Li, with respect to cycle stability over 100 cycles at 1 C. The electrodes processed with a mixture of PVDF/SA show considerable fading and slightly worse values for rate capability. Each one of the different binders used is eco-friendly, and the whole processing can be performed without the use of organic solvents. Further advantages covering the whole production and recycling process, as well as safety issues during operation, encourage deeper research in this area. [ABSTRACT FROM AUTHOR]

All-solid-state batteries were fabricated by assembling a layer of self-organized TiO2 nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO4 as a cathode. The synthesis of self-organized TiO2 NTs from Ti-6Al-4V alloy was carried out via one-step electrochemical anodization in a fluoride ethylene glycol containing electrolytes. The electrodeposition of the polymer electrolyte onto anatase TiO2 NTs was performed by cyclic voltammetry. The anodized Ti-6Al-4V alloys were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the anodized Ti-6Al-4V alloys were investigated by cyclic voltammetry and chronopotentiometry techniques. The full-cell shows a high first-cycle Coulombic efficiency of 96.8% with a capacity retention of 97.4% after 50 cycles and delivers a stable discharge capacity of 63 μAh cm−2 μm−1 (119 mAh g−1) at a kinetic rate of C/10. [ABSTRACT FROM AUTHOR]

Na3V(PO4)2 was reported recently as a novel cathode material with high theoretical energy density for Sodium-ion batteries (SIBs). However, whether V3+/V4+/V5+ multielectron reactions can be realized during the charging process is still an open question. In this work, Na3V(PO4)2 is synthesized by using a solid-state method. Its atomic composition and crystal structure are verified by X-ray diffraction (XRD) and neutron diffraction (ND) joint refinement. The electrochemical performance of Na3V(PO4)2 is evaluated in two different voltage windows, namely 2.5–3.8 and 2.5–4.3 V. 51V solid-state NMR (ssNMR) results disclose the presence of V5+ in Na2−xV(PO4)2 when charging Na3V(PO4)2 to 4.3 V, confirming Na3V(PO4)2 is a potential high energy density cathode through realization of V3+/V4+/V5+ multielectron reactions. [ABSTRACT FROM AUTHOR]

Sodium and magnesium batteries with intercalation electrodes are currently alternatives of great interest to lithium in stationary applications, such as distribution networks or renewable energies. Hydrated laminar oxides such as birnessites are an attractive cathode material for these batteries. Sodium and potassium birnessite samples have been synthesized by thermal and hydrothermal oxidation methods. Hybrid electrochemical cells have been built using potassium birnessite in aqueous sodium electrolyte, when starting in discharge and with a capacity slightly higher than 70 mA h g−1. Hydrothermal synthesis generally shows slightly poorer electrochemical behavior than their thermal counterparts in both sodium and potassium batteries. The study on hybrid electrolytes has resulted in the successful galvanostatic cycling of both sodium birnessite and potassium birnessite in aqueous magnesium electrolyte, with maximum capacities of 85 and 50 mA h g−1, respectively. [ABSTRACT FROM AUTHOR]

Herein, thermal decomposition experiments of lithium peroxide (Li2O2) were performed to prepare a precursor (Li2O) for sacrificing cathode material, Li2NiO2. The Li2O2 was prepared by a hydrometallurgical reaction between LiOH·H2O and H2O2. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H2O, (2) decomposition of Li2O2, and (3) pyrolysis of the remaining anhydrous LiOH. This stepwise reaction was elucidated by thermal gravimetric and quantitative X-ray diffraction analyses. Furthermore, over-lithiated lithium nickel oxide (Li2NiO2) using our lithium precursor was synthesized, which exhibited a larger yield of 90.9% and higher irreversible capacity of 261 to 265 mAh g−1 than the sample prepared by commercially purchased Li2O (45.6% and 177 to 185 mAh g−1, respectively) due to optimal powder preparation conditions. [ABSTRACT FROM AUTHOR]