Disclosed herein is a battery cell having an electrode assembly including one or more unit cells mounted in a variable cell case in a state in which the electrode assembly is impregnated with an electrolyte, wherein at least one of the unit cells includes a flexible electrode that can be bent or curved, an electrode current collector of the flexible electrode includes a first surface, to which an electrode active material is applied, and a second surface, to which no electrode active material is applied, the second surface being opposite to the first surface, and the second surface is provided with a mesh for improving flexibility of the electrode.

In an embodiment, a Li-ion battery cell comprises an anode electrode with an electrode coating that (1) comprises Si-comprising active material particles, (2) exhibits an areal capacity loading in the range of about 3 mAh/cm.sup.2 to about 12 mAh/cm.sup.2, (3) exhibits a volumetric capacity in the range from about 600 mAh/cc to about 1800 mAh/cc in a charged state of the cell, (4) comprises conductive additive material particles, and (5) comprises a polymer binder that is configured to bind the Si-comprising active material particles and the conductive additive material particles together to stabilize the anode electrode against volume expansion during the one or more charge-discharge cycles of the battery cell while maintaining the electrical connection between the metal current collector and the Si-comprising active material particles.

A lithium ion secondary battery that can operate in a high-temperature environment of 85? C. The lithium ion secondary battery includes a positive electrode active material that can store and release lithium ions Li, a positive electrode binder that binds the positive electrode active material, a negative electrode active material that can store and release lithium ions Li.sup.+, a negative electrode binder that binds the negative electrode active material, and an electrolytic solution containing an organic solvent and an imide-based lithium salt. The negative electrode active material is previously doped with lithium ions. The positive electrode binder has a Hansen solubility parameter-based relative energy difference (RED) value of more than 1 with respect to the electrolytic solution.

A cathode and method of preparing the cathode are disclosed. The cathode includes a current collector, and a cathode active material layer disposed on the current collector, wherein the current collector includes a metal substrate, and a conductive protective layer disposed on at least a portion of the metal substrate, and the conductive protective layer includes one or more of a protrusion and a recess which react with base, a lithium battery including the cathode, and a method of preparing the cathode.

A mesh-shaped, porous electric current density distributor is for use with an electrode, and is adapted for providing electric current to an active layer of the electrode. The active layer contacts a face of the current density distributor, and the current density distributor includes a porous mesh having several electrically conductive paths. At least part of the electrically conductive paths extend along a direction of major current flow over the current density distributor. The porous mesh includes in a direction crosswise to the direction of major electric current flow, several paths of an electric insulator. The current carrying capacity of the current density distributor in crosswise direction to the major current flow over the current density distributor is smaller than the current carrying capacity in the direction along the major current flow over the current density distributor.

The present invention relates to a mesh-shaped, porous electric current density distributor for use with an electrode, the current density distributor being adapted for providing electric current to an active layer of the electrode, which active layer is provided to contact a face of the current density distributor, wherein the current density distributor comprises a porous mesh having a plurality of electrically conductive paths, wherein at least part of the electrically conductive paths extend along a direction of major current flow over the current density distributor. The porous mesh comprises in a direction crosswise to the direction of major electric current flow, a plurality of first paths of an electric insulator. The current carrying capacity of the current density distributor in crosswise direction to the major current flow over the current density distributor is smaller than the current carrying capacity in the direction along the major current flow over the current density distributor.

A method for manufacturing electrodes for a battery cell includes providing a first free-standing electrode; providing a current collector including holes; providing a second free-standing electrode; and laminating the current collector between the first free-standing electrode and the second free-standing electrode using at least one of heat and pressure and without using a solvent.

An electrochemical cell that converts chemical energy to electrical energy includes a cathode with an active material of fluorinated carbon on a perforated metal cathode current collector, a lithium anode on a perforated metal anode current collector, a stepped header, a stable electrolyte, and a separator. In various embodiments, an anode current collector design, a cathode current collector design, a stepped header design, a cathode formulation, an electrolyte formulation, a separator, and a battery incorporating the electrochemical cell are provided.

Tensile strength in a width direction and a longitudinal direction is improved without damaging a ventilation characteristic. A perforated film is a perforated film provided with holes, each of the holes is arranged at an intersection of a plurality of virtual lines extending along a direction and a plurality of virtual lines extending along a direction, and the direction is different from the width direction and the longitudinal direction. The direction and the direction may be both inclined at an angle larger than 30 and smaller than 60 to the width direction.

The present invention relates to a method of preparing a lithium secondary battery which may improve productivity and performance of the lithium secondary battery by visually measuring an electrolyte solution impregnation time for an electrode active material, setting an optimum estimated electrolyte solution impregnation time of the electrolyte solution for a battery based on a measured result, and reflecting the optimum estimated electrolyte solution impregnation time in a production process.