An electrode active material for an electrochemical element of the present invention is a monoclinic niobium complex oxide, and Db/Da is 1.5 or more, where Da is a crystallite size in the a-axis direction, and Db is a crystallite size in the b-axis direction. An electrode material for an electrochemical element of the present invention contains the electrode active material for an electrochemical element of the present invention. An electrode for an electrochemical element of the present invention contains the electrode active material for an electrochemical element of the present invention or the electrode material for an electrochemical element of the present invention. In an electrochemical element of the present invention, either one of a positive electrode and a negative electrode is the electrode for an electrochemical element of the present invention. A movable body of the present invention includes the electrochemical element of the present invention.

The present invention relates to a method for preparing a nano-titanate, a nano-titanic acid and a nano-TiO.sub.2 containing doping E or embedding E nanoparticles, and the use thereof. By using an E-doped Ti-T intermetallic compound as a titanium source, and reacting it with alkaline solution at atmospheric pressure and near its boiling-point temperature, an E-doped titanate nanofilm is prepared with high efficiency and in a short time. Through acid treatment and (or) heat treatment, a titanate nanofilm containing embedding E nanoparticles, an E-doped titanic acid nanofilm, and a titanic acid nanofilm and a TiO.sub.2 flake powder containing embedding E nanoparticles can be further prepared. Through a subsequent reaction at high temperature and pressure, the preparation of an E-doped titanate nanotubes and titanic acid nanotubes, and titanic acid nanotubes and TiO.sub.2 nanotubes/nanorods containing embedding E nanoparticles can be achieved in high efficiency and low-cost.

The present invention is directed to compositions comprising at least one layer or at least two layers, each layer comprising a substantially two-dimensional array of crystal cells, having first and second surfaces, each crystal cell having the empirical formula of M.sub.n+1X.sub.n, where M, X, and n are described in the specification, and devices incorporating these compositions.

A highly scalable process has been developed for stabilizing large quantities of the zeta-polymorph of V.sub.2O.sub.5, a metastable kinetically trapped phase, with high compositional and phase purity. The process utilizes a beta-Cux V.sub.2O.sub.5 precursor which is synthetized from solution using all-soluble precursors. The copper can be leached from this structure by a room temperature post-synthetic route to stabilize an empty tunnel framework entirely devoid of intercalating cations. The metastable ?-V.sub.2O.sub.5 thus stabilized can be used as a monovalent-(Li, Na) or multivalent-(Mg, Ca, Al) ion battery cathode material.

Disclosed are a silicon carbon composite anode material, a method of preparing the same, and a secondary battery including the same. In one embodiment, the anode material comprises: a primary particle comprising a first hollow core having a first hollow portion therein and nano-silicon particles packed in the first hollow portion; and a secondary particle comprising a second hollow core having a second hollow portion therein and at least one primary particle packed in the second hollow portion, wherein the first hollow core has a different hardness than the second hollow core.

The present invention provides a positive electrode composite material, a preparation method thereof, a positive electrode and a lithium ion secondary battery. The positive electrode composite material comprises: a positive electrode matrix material doped with Mg element; and a fluoride present on the surface of the positive electrode matrix material in a dotted form, the fluoride containing MgF.sub.2. By the positive electrode composite material, the method for preparing the positive electrode composite material, and the positive electrode and the lithium ion secondary battery which contain the positive electrode composite material in the present invention, the positive electrode matrix material in the lithium ion secondary battery can be effectively prevented from being corroded by an electrolyte, and more lithium ion channels can be reserved, thereby improving the cycle performance of the lithium ion secondary battery, and reducing the impedance increase of the lithium ion secondary battery while not affecting the capacity and initial impedance of the lithium ion secondary battery.

The present disclosure provides a porous silicon-carbon anode electrode material. The anode electrode material has a core-shell structure and the core-shell structure sequentially includes a porous sparse silicon-carbon core, a transition layer, a dense silicon-carbon layer, and a carbon coating layer from inside to outside. Porous carbon of the porous silicon-carbon anode electrode material in the present disclosure has a porous gap structure. Metal elements doped in the porous carbon with the silicon particles distributed in the gaps of the carbon skeleton structure, the carbon coating layer, and the dense carbon layer have good electrical conductivity, which may improve the conductivity of the material. The silicon particles in the porous silicon-carbon anode electrode material are reasonably distributed in gaps between carbon particles of porous carbon, effectively slow down the expansion of the silicon anode electrode material in the cycling process, control capacity fade, and improve cycling stability

A two-dimensional perovskite material, a dielectric material including the same, and a multi-layered capacitor. The two-dimensional perovskite material includes a layered metal oxide including a first layer having a positive charge and a second layer having a negative charge which are laminated, a monolayer nanosheet exfoliated from the layered metal oxide, a nanosheet laminate of a plurality of the monolayer nanosheets, or a combination thereof, wherein the two-dimensional perovskite material a first phase having a two-dimensional crystal structure is included in an amount of greater than or equal to about 80 volume %, based on 100 volume % of the two-dimensional perovskite material, and the two-dimensional perovskite material is represented by Chemical Formula 1.

An electrochemical cell includes a cathode including an early transition metal fluoro-bronze; an anode including magnesium metal; and an electrolyte; wherein: the early transition metal fluoro-bronze is configured for intercalation of magnesium ions.

A powder for use in a negative electrode of a battery, the powder comprising particles, the particles comprising a matrix material and silicon-based particles dispersed in said matrix material, the powder having a total specific volume of open porosity at least equal to 0.005 cm.sup.3/g and at most equal to 0.05 cm.sup.3/g, a total specific volume of closed porosity at least equal to 0.01 cm.sup.3/g and at most equal to 0.1 cm.sup.3/g, and a ratio of the total specific volume of open porosity over the total specific volume of closed porosity at least equal to 0.01 and at most equal to 0.99.