An electrochemical device includes a positive electrode plate, a negative electrode plate and a separator disposed between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material having lithium cobalt oxide. The negative electrode plate includes a negative current collector and a negative active material layer disposed on the negative current collector. The negative active material layer includes a negative active material. The electrochemical device satisfies 3≤100×(4.5−U)−10×(CB−1)≤10, CB=(A′×B′×C′)/(A×B×C). Increasing the CB value of the electrochemical device and reducing the charge cutoff voltage U, reduces volume expansion of the negative active material layer during charging and discharging, prevents the rise of the positive electrode potential from adversely affecting the positive active material, thereby improving the cycle performance of electrochemical device.

An electrochemical apparatus includes a positive electrode plate and a negative electrode plate, the negative electrode plate includes a negative electrode current collector and a negative electrode active substance layer disposed on a surface of the negative electrode current collector; the negative electrode active substance layer includes an active material layer and a lithium-containing layer provided on a surface of the active material layer; and the active material layer includes a SiOC material and graphite. The negative electrode material provided in this application can improve the first-cycle coulombic efficiency and energy density of the electrochemical apparatus.

A porous reduced silica fiber material has a diameter of about 0.1 to about 20 microns and a surface area of about 5 m.sup.2/g to about 400 m.sup.2/g. The porous reduced fiber material may be used to form an electrode having a high capacity and improved cycle life over comparable commercial silicon electrodes.

A method of producing a powder mass for a lithium battery, the method comprising: (a) providing a solution containing a sulfonated elastomer dissolved in a solvent or a precursor in a liquid form or dissolved in a solvent; (b) dispersing a plurality of particles of a cathode active material in the solution to form a slurry; and (c) dispensing the slurry and removing the solvent and/or polymerizing/curing the precursor to form the powder mass, wherein the powder mass comprises multiple particulates and at least a particulate comprises one or a plurality of particles of a cathode active material being encapsulated by a thin layer of sulfonated elastomer having a thickness from 1 nm to 10 μm, a fully recoverable tensile strain from 2% to 800%, and a lithium ion conductivity from 10.sup.−7 S/cm to 5×10.sup.−2 S/cm at room temperature.

A positive electrode material which is used in a positive electrode of a lithium ion secondary battery disclosed here includes a positive electrode active material including a compound capable of storing and releasing lithium ions, a first coating material disposed on at least a part of the surface of the positive electrode active material, and a second coating material disposed on at least a part of the surface of the positive electrode active material. The positive electrode material is characterized in that the first coating material contains a nickel oxide having a rock salt structure, and the second coating material contains a titanium oxide.

A negative electrode material of the lithium-ion battery, a preparation method therefor and an application thereof, and a lithium-ion battery include the same are provided. The negative electrode material has a core-shell structure. The core has a silicon-containing material while the shell has an organic lithium salt and a porous carbon film, and at least part of lithium ion is intercalated in the porous carbon film. The negative electrode material is prepared by (1) mixing a silicon source and a carbon source, and then calcining the mixture; (2) mixing the calcined product obtained in the step (1) with the organic lithium salt; and (3) subjecting the materials obtained in the step (2) of mixing to vacuum freeze-drying.

A battery comprising an acidified metal oxide (“AMO”) material, preferably in monodispersed nanoparticulate form 20 nm or less in size, having a pH<7 when suspended in a 5 wt % aqueous solution and a Hammett function H.sub.0>−12, at least on its surface.

An electrochemical pretreatment method of a vanadium positive electrode for a lithium secondary battery, which can improve the lifetime characteristics of the positive electrode and the battery by inhibiting the leaching of vanadium when charging and discharging the lithium secondary battery using, for instance, vanadium oxide (V.sub.2O.sub.5) as a positive electrode, and a vanadium positive electrode for a lithium secondary battery pretreated thereby. The electrochemical pretreatment method of the vanadium positive electrode for a lithium secondary battery includes a) a step of discharging the lithium free vanadium positive electrode at a voltage of 1.9 V or more; b) an electrochemical pretreatment step of maintaining the discharged vanadium positive electrode of a) at an onset potential value or a potential value having a maximum current through a potentiostat; and c) a step of charging and discharging the pretreated vanadium positive electrode of b) at a voltage range of 2.1V to 4.0V.

The present invention provides a binder for a secondary battery having excellent binding force. A binder for a secondary battery comprising a polymer compound, wherein the polymer compound contains an acrylic repeating unit, and a 3% by mass aqueous solution of the polymer compound has a yellowness index of 14 or less.

A negative active material for a rechargeable lithium battery includes a core including a SiO.sub.2 matrix and a Si grain, and a coating layer continuously or discontinuously coated on the core. The coating layer includes SiC and C, and the peak area ratio of the SiC (111) plane to the Si (111) plane as measured by X-ray diffraction analysis (XRD) using a CuKα ray ranges from about 0.01 to about 0.5.