The influence of Mn-ion dissolved in electrolyte solution on the electrochemical properties graphite negative-electrodes was investigated using edge plane highly oriented pyrolytic (HOPG) by cyclic voltammetry, impedance spectroscopy, and situ atomic force microscopy (AFM). Redox currents due to intercalation de-intercalation reactions Li-ion at an HOPG electrode significantly decreased with increase cycle number. Both surface film interfacial transfer resistances remarkably increased...

The effect of phosphorus (P)-doping on the electrochemical performance Si negative electrodes in lithium-ion batteries was investigated. Field-emission scanning electron microscopy used to observe changes surface morphology. Surface crystallinity and phase transition before after a charge–discharge cycle were investigated by Raman spectroscopy X-ray diffraction. Li insertion energy into also calculated based computational chemistry. results showed that low P concentration 124 ppm has...

We evaluated the charge–discharge performance of a Sn4P3 negative electrode in an ionic liquid electrolyte comprised N-methyl-N-propylpyrrolidinium bis(fluorosulfonyl)amide (Py13-FSA) and NaFSA. also conducted cyclic voltammetry transmission electron microscopy for to reveal reaction mechanism. It was suggested that Na15Sn4 Na3P are formed via phase separation first sodiation elemental Sn P by following desodiation with Na ions subsequent cycles. The exhibited high Coulombic efficiency 99.1%...

Elemental Si has a high theoretical capacity and attracted attention as an anode material for energy density lithium-ion batteries. Rapid fading is the main problem with Si-based electrodes; this mainly because of massive volume change in during lithiation-delithiation. Here, we report that combining ionic-liquid electrolyte charge limit 1000 mA h g-1 significantly suppresses expansion, improving cycle life. Phosphorus-doping also enhances suppression increases Li+ diffusion coefficient. In...

Changes in the surface morphology of edge planes graphite during a potential sweep were studied using highly oriented pyrolytic (HOPG) an ethylene carbonate (EC) + diethyl (DEC)-based electrolyte solution by situ atomic force microscopy (AFM). The effects microscopic structures graphite, i.e., and basal planes, on film formation are discussed. fine particles precipitates was observed depending electrode between 1.0 0 V. These considered to be remnants blisters that could at plane...

Rutile-type titanium oxide (TiO2) is a resource-rich and inexpensive material with one-dimensional ion-diffusion path along the c-axis. However, it has received no attention as an anode for Na-ion batteries because of its low electronic conductivity limited ion diffusion in ab-plane direction. We have revealed first time reversible Na insertion–extraction reaction rutile TiO2 recently reported improvement performances by doping various impurity elements such Nb5+, Ta5+, In3+. In this Review,...

As anode materials of Li-ion and Na-ion batteries, the electrochemical insertion/extraction reactions Li Na were investigated for a rutile-type Nb-doped TiO2 synthesized by sol–gel method. We changed particle crystallite sizes rutile powders annealing at various temperatures between 100 1000 °C prepared thick-film electrodes consisting powders. The performances remarkably improved not only in battery but also with reduced temperature 400 from °C. revealed that showing better high-rate...

It is reported that silicon (Si) anodes with a smaller crystallite size show better electrochemical performance in lithium‐ion batteries (LIBs); Si particles different diameters are also used. However, it yet to be clarified whether the attributed or particle diameter. The effect of on its anode using having same diameter and sizes investigated. Longer cycle life obtained for size, due small amount amorphous Li‐rich Li—Si phase formed during charging. likely form greater larger leading...

We investigated the impacts of MnO2 crystal structures and Fe doping into on photoelectrochemical charge–discharge properties composite electrodes composed TiO2 polymorphs (α-, β-, γ-, δ-phases) in aqueous Na2SO4 solution. In a conventional electrochemical capacitor, α-MnO2 electrode delivered highest specific capacitance among undoped because its larger tunnel structure compared with β- γ-MnO2. Since electronic conductivity δ-MnO2 was very low, performance poor despite large interlayer...

Surface films formed on edge plane pyrolytic graphite electrodes were characterized by attenuated total reflection (ATR)-Fourier transform infrared spectroscopy (FTIR). FTIR-ATR spectra revealed that the surface consisted mainly of LiOCO2R (R = alkyl or lithium carbonate), Li2CO3 and (CH2CH2O)n both basal planes, while formation reactions at proceeded more rapidly than those plane. The major constituents 0.1 0.8 V Li2CO3, respectively. We discuss this difference based results in literature....

The effects of film-forming additives in electrolyte solutions on the formation a surface film edge plane pyrolytic graphite electrodes lithium ion batteries were investigated by electrochemical atomic force microscopy (AFM). Surface films formed at around 1.2 V through reductive decomposition including vinyl ethylene carbonate. thickness films, ca. 20 nm, was less than half that for an with no additives, and remained unchanged after second potential cycle. Most could be scraped off repeated...

The effect of pre-lithiation on the electrochemical performance Si negative electrodes for lithium-ion batteries was studied. A pre-volume-expansion induced by is expected to decrease relative change in volume during charge-discharge reactions. Suppression should improve cycle performance, Coulombic efficiency, and so on. When mechanically pre-doped Li extracted from Li-Si alloy first cycle, an electrode exhibited poor just like a Si-alone electrode. On other hand, Li1.00Si improved higher...

Single-crystalline Nb-doped TiO2 particles were hydrothermally synthesized for Na-storage materials. Annealing in air changed the particle color from blue to white. The successful introduction of oxygen vacancies into without annealing was confirmed by lattice expansion, reduced electrical resistivity, a Raman peak shift, and presence {110} stacking faults due streaks along ⟨110⟩ reciprocal directions electron diffraction. significantly enhanced reversible capacity electrode because improved...

We investigated the Li storage properties of spindle single-crystalline rutile TiO2 fine particles synthesized by a large-scale sulfate process. Their anode were compared with those polycrystalline particles. An increase in degree single-crystal formation improved charge–discharge capacity and initial Coulombic efficiency. In situ X-ray diffraction transmission electron microscopic observation demonstrated structural integrity during reactions. These results concluded that is critical...

We attempted to improve electrochemical performances of a rutile TiO2 electrode as Li-ion battery anode by doping with two kinds elements different ionic sizes. When Nb5+ and Fe3+ were doped into TiO2, the total amount could be increased up 11 at.% because amounts (9 at.%) (2 exceed their solubility limits. It is considered that compressive strain caused larger than Ti4+ partially offset tensile induced smaller Fe3+. The Fe–Nb-doped exhibited an excellent cycle performance good high-rate...

To suppress the degradation of graphite negative-electrodes that is caused by dissolution Mn-containing positive-electrode materials, effects additives should strongly interact with Mn ion in electrolyte solution were examined. The edge plane highly oriented pyrolytic (HOPG) was used as a model electrode, and its electrochemical properties investigated cyclic voltammetry impedance spectroscopy Mn-ion-containing solution. 100 ppm dissolved significant decrease redox currents due to...

Sodiation–desodiation behaviors were investigated for electrodes composed of various binary phosphides, InP, CuP2, GeP, SiP, and LaP, as anode materials a Na-ion battery. Although LaP electrode did not react with Na, the other showed reversible sodiation–desodiation reactions in initial cycles. Rapid capacity decays observed SiP electrodes. In contrast, better cyclability was attained InP electrode. These results indicate that phosphides (M–P) require four properties improving cyclability:...

Lithium-ion batteries have attracted considerable attention due to their high power density. The change in concentration of salt the electrolyte solution lithium-ion during operation causes serious degradation battery performance. Herein, a new method situ Raman spectroscopy with ultrafine multifiber probes was developed simultaneously study concentrations ions at several different positions deep narrow spaces between electrodes batteries. total amount clearly changed low permeability...

We hydrothermally synthesized various-element-doped rutile TiO2 for Na-ion battery anodes. Sn- and In-doped electrodes showed poor performances. In contrast, Ta- Nb-doped exhibited larger discharge capacities, which is attributed to an expanded diffusion path improved electronic conductivity. Among them, the Ta-doped one delivered excellent cycling performance better rate capability. A first-principles calculation revealed that Ta doping reduced electron charge density in rutile's...