An energy storage device is provided that has improved power performance at low temperature. In the present embodiment, an energy storage device is provided that includes an electrode having an active material layer, the active material layer contains at least active material particles, the particles contained in the active material layer gives a volume-based particle size frequency distribution that has a first peak and a second peak appearing in a particle size larger than a particle size of the first peak, and particles having particle sizes equal to or smaller than a particle size Dx have a volume proportion of 49% or more and 62% or less in a volume of whole particles contained in the active material layer, with the particle size Dx defined as a particle size at a local minimum frequency between the first peak and the second peak in the particle size frequency distribution.

The present invention provides methods for forming apparatus and devices including an anode including at least one metallic lithium layer and at least one backing layer, at least one cathode/counter electrode, at least one separator disposed between the anode and the at least one cathode/counter electrode and an electrolyte, wherein the apparatus is configured to provide a lithium utilization efficiency of at least 80% and wherein the at least one backing layer weighs less than 30% of a copper backing layer of the same dimensions.

Provided is a lithium titanate powder for an electrode of an energy storage device, the lithium titanate powder comprising Li.sub.4Ti.sub.5O.sub.12 as a main component, wherein, when the volume surface diameter calculated from the specific surface area determined by the BET method is represented as D.sub.BET and the crystallite diameter calculated from the half-peak width of the peak of the (111) plane of Li.sub.4Ti.sub.5O.sub.12 by the Scherrer equation is represented as D.sub.X, D.sub.BET is 0.1 to 0.6 μm, D.sub.X is greater than 80 nm, and (D.sub.BET/D.sub.X (μm/μm)) the ratio of D.sub.BET to D.sub.X is 3 or less. Also provided are an active material including the lithium titanate powder and an energy storage device using the active material.

Provided is a lithium titanate powder for an electrode of an energy storage device, the lithium titanate powder comprising Li.sub.4Ti.sub.5O.sub.12 as a main component, wherein, when the volume surface diameter calculated from the specific surface area determined by the BET method is represented as D.sub.BET and the crystallite diameter calculated from the half-peak width of the peak of the (111) plane of Li.sub.4Ti.sub.5O.sub.12 by the Scherrer equation is represented as D.sub.X, D.sub.BET is 0.1 to 0.6 μm, D.sub.X is greater than 80 nm, and (D.sub.BET/D.sub.X (μm/μm)) the ratio of D.sub.BET to D.sub.X is 3 or less. Also provided are an active material including the lithium titanate powder and an energy storage device using the active material.

A thin flexible conformable electrochemical cell for powering a wearable electrical device comprising an inner electrode having an active electrode face of one charge and an outer electrode having an active electrode face of the opposite charge separated by a separator, wherein said separator comprises an electrolyte layer as a single continuous layer folded around the inner electrode, and wherein the cell has a single continuous flexible coating material folded around the separator and the inner electrode so as to offer protection for the cell, and wherein the coating material is sealable so as define access to the cell for electrode contacts for connection with the electrical device, and so as to offer avoidance of the cell short circuiting in use. Also provided are methods for cell preparation.

A thin flexible conformable electrochemical cell for powering a wearable electrical device comprising an inner electrode having an active electrode face of one charge and an outer electrode having an active electrode face of the opposite charge separated by a separator, wherein said separator comprises an electrolyte layer as a single continuous layer folded around the inner electrode, and wherein the cell has a single continuous flexible coating material folded around the separator and the inner electrode so as to offer protection for the cell, and wherein the coating material is sealable so as define access to the cell for electrode contacts for connection with the electrical device, and so as to offer avoidance of the cell short circuiting in use. Also provided are methods for cell preparation.

This undercoat foil for an energy storage device electrode comprises a collector base plate, and an undercoat layer formed on at least one surface of the collector base plate, the undercoat layer containing carbon nanotubes, and the coating amount per collector base plate surface being 0.1 g/m.sup.2 or less. Since this undercoat foil can be effectively welded by ultrasound, the use thereof allows a low-resistance energy storage device and a simple and effective production method therefor to be provided.

The present invention relates to a lithium-sulfur ultracapacitor including a cathode containing a sulfur-porous carbon composite material; a separator; a lithium metal electrode disposed on an opposite side of the cathode with respect to the separator; a graphite-based electrode disposed adjacent to the lithium metal electrode; and an electrolyte impregnating the cathode, the lithium metal electrode, and the graphite-based electrode, wherein the lithium metal electrode and the graphite-based electrode together constitute an anode, and a method of preparing the lithium-sulfur ultracapacitor. According to the present invention, since the lithium metal electrode and the graphite-based electrode are adjacent to each other, lithium ions arising from the lithium metal electrode are pre-doped on the graphite-based electrode due to an internal short circuit between the lithium metal electrode and the graphite-based electrode, migrate from the graphite-based electrode to the cathode during a discharging process, and migrate from the cathode to the graphite-based electrode during a charging process, and such migrations contribute to excellent charging and discharging properties of the lithium-sulfur ultracapacitor.

An energy storage capacitor having a composite electrode structure includes: a case; a rolled body arranged inside the case; and an electrolyte stored inside the case. The rolled body includes: a first anode foil having a first anode lead plate connected at one side of one surface, a first cathode foil arranged to face the other surface of the first cathode foil with the one surface of the first anode foil and a first cathode lead plate connected at the other side, a second cathode foil arranged to face the other surface of the second cathode foil with one surface of the first cathode foil and having a second cathode lead plate connected at one side of one surface, a second anode foil arranged to face the one surface of the second cathode foil and a second anode lead plate connected at the other side.

A negative electrode material for a power storage device contains a single-phase porous carbon material capable of electrochemically occluding and releasing lithium ions, the single-phase porous carbon material has a BET specific surface area of not less than 100 m.sup.2/g, and a cumulative volume of pores having a pore diameter of 2 nm to 50 nm in a pore diameter distribution of the single-phase porous carbon material is not less than 25% of a total pore volume.