The present invention relates to a carbonaceous material which is derived from a plant, having a specific surface area of 1800 to 3000 m.sup.2/g as measured by a BET method, a hydrogen element content of 0.42% by mass or less and an oxygen element content of 1.5% by mass or less.

Provided is a conductive carbon mixture which is to be used together with an electrode active material in manufacturing an electrode of an electricity storage device and enables the manufacture of the electricity storage device having a good cycle life. The conductive carbon mixture for manufacturing an electrode of an electricity storage device comprises an oxidized carbon having electrical conductivity and a different conductive carbon which is different from the oxidized carbon, wherein the oxidized carbon covers the surface of the different conductive carbon. The conductive carbon mixture is characterized in that the ratio of the peak intensity of the 2D band to the peak intensity of the D band in a Raman spectrum of the conductive carbon mixture is 55% or less relative to the ratio of the peak intensity of the 2D band to the peak intensity of the D band in a Raman spectrum of the different conductive carbon. This conductive carbon mixture covers the surface of the electrode active material in a particularly good manner and thus prolongs the cycle life of the electricity storage device.

An energy storage device according to an aspect of the present invention includes a negative electrode and a positive electrode, the negative electrode includes a negative substrate and a negative active material layer directly or indirectly layered on the negative substrate, the negative active material layer contains a negative active material, the negative active material contains solid graphite particles as a main component, the aspect ratio of the solid graphite particles is 1 or more and 5 or less, and a negative electrode utilization factor that is the proportion of the amount of charge per mass of the negative active material in a full charge state to a theoretical capacity per mass of graphite is 0.65 or more.

The present invention relates to an additive for an electrochemical device positive electrode comprising a porous carbon material, wherein the porous carbon material has a pore volume of pores having a diameter of 2 nm or more of 0.25 cm.sup.3/g or more, a pore volume of pores having a diameter of less than 2 nm of 0.5 cm.sup.3/g or less, and an ash content of 0.5% by weight or less.

Electrolytes and electrolyte additives for energy storage devices comprising linear carbonate compounds.

Electrolytes and electrolyte additives for energy storage devices comprising linear carbonate compounds.

An aspect of the present invention is an energy storage device including: a negative electrode including a pair of flat portions facing each other and a curved folding portion connecting end portions on one side of the pair of flat portions to each other; and a sheet-like positive electrode disposed between the pair of flat portions of the negative electrode, in which the negative electrode includes a negative electrode substrate and a negative active material layer stacked on a surface of the negative electrode substrate directly or indirectly in a non-pressed or low-pressure pressed state, the negative active material layer contains a negative active material, the negative active material contains solid graphite particles, and the solid graphite particle has an aspect ratio of 1 or more and 5 or less.

An energy storage device according to one aspect of the present invention includes: an electrode assembly including a positive electrode, a negative electrode, and a separator; a nonaqueous electrolyte; and a case for housing the electrode assembly and the nonaqueous electrolyte, in which the positive electrode contains a positive active material, the positive active material contains a plurality of particles satisfying at least one of conditions (1) and (2) below, and the electrode assembly is in a pressed state. (1) A plurality of primary particles that do not form secondary particles (2) A plurality of secondary particles formed by aggregation of a plurality of primary particles, having a ratio of an average diameter of the secondary particles to an average diameter of the primary particles that form the secondary particles of less than 11

An energy storage device can include a cathode, an anode, and a separator between the cathode and the anode, where the anode and/or electrode includes an electrode film having a super-fibrillized binder material and carbon. The electrode film can have a reduced quantity of the binder material while maintaining desired mechanical and/or electrical properties. A process for fabricating the electrode film may include a fibrillization process using reduced speed and/or increased process pressure such that fibrillization of the binder material can be increased. The electrode film may include an electrical conductivity promoting additive to facilitate decreased equivalent series resistance performance. Increasing fibrillization of the binder material may facilitate formation of thinner electrode films, such as dry electrode films.

An energy storage device can include a cathode, an anode, and a separator between the cathode and the anode, where the anode and/or electrode includes an electrode film having a super-fibrillized binder material and carbon. The electrode film can have a reduced quantity of the binder material while maintaining desired mechanical and/or electrical properties. A process for fabricating the electrode film may include a fibrillization process using reduced speed and/or increased process pressure such that fibrillization of the binder material can be increased. The electrode film may include an electrical conductivity promoting additive to facilitate decreased equivalent series resistance performance. Increasing fibrillization of the binder material may facilitate formation of thinner electrode films, such as dry electrode films.