A method of forming a sulfur-based cathode material includes: 1) providing a sulfur-based nanostructure; 2) coating the nanostructure with an encapsulating material to form a shell surrounding the nanostructure; and 3) removing a portion of the nanostructure through the shell to form a void within the shell, with a remaining portion of the nanostructure disposed within the shell.

A method of forming a sulfur-based cathode material includes: 1) providing a sulfur-based nanostructure; 2) coating the nanostructure with an encapsulating material to form a shell surrounding the nanostructure; and 3) removing a portion of the nanostructure through the shell to form a void within the shell, with a remaining portion of the nanostructure disposed within the shell.

Ultra-thin lithium ion capacitors with ultra-high power performance are provided. Ultra-thin electrodes and ultra-thin lithium films can be used for the ultra-thin lithium ion capacitor. A lithium ion capacitor can include a first positive electrode and a second positive electrode, a negative electrode disposed between the first positive electrode and the second positive electrode, a first lithium film disposed between the first positive electrode and the negative electrode, and a second lithium film disposed between the second positive electrode and the negative electrode. Each of the first and second lithium films can include an electrolyte. In addition, at least one separator can be provided between the first positive electrode and the first lithium film, and at least one separator can be provided between the second positive electrode and the second lithium film.

A low oxygen-type silicon nanoparticle-containing slurry that can inhibit a viscosity increase along with the nanosizing of silicon particles is provided. The low oxygen-type silicon nanoparticle-containing slurry can be used for the production of a lithium-ion secondary battery having excellent charge-discharge characteristics such as charge-discharge capacity, initial coulombic efficiency, and charge-discharge cycle characteristics. The low oxygen-type silicon nanoparticle-containing slurry contains low oxygen-type silicon nanoparticles, a nonaqueous solvent, and an additive. The low oxygen-type silicon nanoparticles have a ratio of a peak area (ii) in a range of −100 to −110 ppm to a peak area (i) in a range of −75 to −85 ppm [a (ii)/(i) ratio] of 1.0 or less in .sup.29Si-NMR.

An object of the present invention is to provide a carbonaceous material suitable as an electrode material of an electrochemical device which is increased in capacity with not only suppression of an increase in irreversible capacity, but also securement of a high electrode density, as well as a method for producing the carbonaceous material The present invention relates to a carbonaceous material for an electrochemical device, having a specific surface area of 23 m.sup.2/g or less as measured according to a BET method and an aerated energy (AE) of 40 mJ or more and 210 mJ or less as measured with a powder rheometer.

The present invention relates to an anode active material for lithium secondary battery and a lithium secondary battery comprising the same. The anode active material for lithium secondary batteries comprises two kinds of crystalline carbon, with the peak intensity ratio of 3R(101) face to 2H(100) face I.sub.3R(101)/I.sub.2H(100) ranging from 0.55 to 0.7 in an X-ray diffraction pattern.

A method of manufacturing a free-standing electrode film includes preparing a mixture including an electrode active material, a binder, and an additive solution or conductive paste, the additive solution or conductive paste being in an amount less than 5% by weight of the mixture and including a polymer additive and a liquid carrier, as well as a conductive material in the case of a conductive paste. The mixture may have total solid contents greater than 95% by weight. Preparing the mixture may include mixing the additive solution or conductive paste with the electrode active material to lubricate the electrode active material and subsequently adding and mixing in the binder. The method may further include subjecting the mixture to a shear force and, after the mixture has been subjected to the shear force, pressing the mixture into a free-standing film.

An aspect of the present invention is an energy storage device including: an electrode assembly obtained by winding a band-shaped positive electrode including a positive active material layer, a band-shaped negative electrode including a negative active material layer, and a band-shaped separator in the longitudinal direction; an electrolyte solution; and a case that houses the electrode assembly and the electrolyte solution, where at least one of the positive active material layer and the negative active material layer contains a hollow active material particle, the winding axis of the electrode assembly is located parallel to the horizontal direction, at least a central part of the electrode assembly is pressed with the case pressed, an excess electrolyte solution that is a part of the electrolyte solution is present between the electrode assembly and the case, the lower end of the electrode assembly has contact with the excess electrolyte solution, and the relationship between the height H from the liquid level of the excess electrolyte solution to the upper end of the electrode assembly and the width We of the positive active material layer satisfies the following formula 1:

0.8H≤Wc≤2.0H  1

A porous carbon that has an extremely high specific surface area while being crystalline, and a method of manufacturing the porous carbon are provided. A porous carbon has mesopores 4 and a carbonaceous wall 3 constituting an outer wall of the mesopores 4, wherein the carbonaceous wall 3 has a portion forming a layered structure. The porous carbon is fabricated by mixing a polyamic acid resin 1 as a carbon precursor with magnesium oxide 2 as template particles; heat-treating the mixture in a nitrogen atmosphere at 1000° C. for 1 hour to cause the polyamic acid resin to undergo heat decomposition; washing the resultant sample with a sulfuric acid solution at a concentration of 1 mol/L to dissolve MgO away; and heat-treating the noncrystalline porous carbon in a nitrogen atmosphere at 2500° C.

A porous carbon that has an extremely high specific surface area while being crystalline, and a method of manufacturing the porous carbon are provided. A porous carbon has mesopores 4 and a carbonaceous wall 3 constituting an outer wall of the mesopores 4, wherein the carbonaceous wall 3 has a portion forming a layered structure. The porous carbon is fabricated by mixing a polyamic acid resin 1 as a carbon precursor with magnesium oxide 2 as template particles; heat-treating the mixture in a nitrogen atmosphere at 1000° C. for 1 hour to cause the polyamic acid resin to undergo heat decomposition; washing the resultant sample with a sulfuric acid solution at a concentration of 1 mol/L to dissolve MgO away; and heat-treating the noncrystalline porous carbon in a nitrogen atmosphere at 2500° C.