The present invention relates to a battery cell comprising a separator in which a perforated line and magnetic bodies adjacent to the perforated line are formed, and a method for evaluating battery cell safety by using same, wherein the battery cell can induce an internal short circuit without physical deformation of the cell structure, and can be effectively applied to evaluation of battery cell safety against an internal short circuit.

A lithium secondary battery which includes an electrode assembly in which a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate are wound in one direction, a battery can in which the electrode assembly is accommodated, and a sealing body which seals an open end of the battery can. The positive electrode plate includes positive electrode active material comprising single particles, quasi-single particles, or a combination thereof, and the positive electrode active material has D.sub.min of 1.0 μm or more.

A lithium secondary battery which includes an electrode assembly in which a positive electrode plate, a negative electrode plate, and a separator interposed between the positive electrode plate and the negative electrode plate are wound in one direction, a battery can in which the electrode assembly is accommodated, and a sealing body which seals an open end of the battery can. The positive electrode plate includes positive electrode active material comprising single particles, quasi-single particles, or a combination thereof, and the positive electrode active material has D.sub.min of 1.0 μm or more.

A battery, in which a damage on an electrode tab group is suitably inhibited, is provided. The herein disclosed battery satisfies D1>D2 in the case where a length of an interval from a first end part existing in a surface direction along the first side wall to a positive electrode tab join part is treated as D1 and a length of an interval from a second end part to a negative electrode tab join part in the above described surface direction is treated as D2.

A battery, in which a damage on an electrode tab group is suitably inhibited, is provided. The herein disclosed battery satisfies D1>D2 in the case where a length of an interval from a first end part existing in a surface direction along the first side wall to a positive electrode tab join part is treated as D1 and a length of an interval from a second end part to a negative electrode tab join part in the above described surface direction is treated as D2.

This application relates to a battery comprising a positive electrode plate, a separator, and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and at least two layers of positive active material coated on at least one surface of the positive electrode current collector, and wherein an underlying positive active material layer in contact with the positive electrode current collector comprises a first positive active material, a first polymer material and a first conductive material; and wherein an upper positive active material layer in contact with the underlying positive active material layer and away from the positive electrode current collector comprises a second positive active material, a second polymer material and a second conductive material, and the first polymer material comprises fluorinated polyolefin and/or chlorinated polyolefin polymer material. The battery has good safety and improved electrical properties.

This application relates to a battery comprising a positive electrode plate, a separator, and a negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and at least two layers of positive active material coated on at least one surface of the positive electrode current collector, and wherein an underlying positive active material layer in contact with the positive electrode current collector comprises a first positive active material, a first polymer material and a first conductive material; and wherein an upper positive active material layer in contact with the underlying positive active material layer and away from the positive electrode current collector comprises a second positive active material, a second polymer material and a second conductive material, and the first polymer material comprises fluorinated polyolefin and/or chlorinated polyolefin polymer material. The battery has good safety and improved electrical properties.

Disclosed are a secondary battery, a battery module and an electric vehicle. The secondary battery includes an electrode assembly, a housing and a top cover assembly. The housing has an accommodating chamber, the accommodating chamber having an opening, and the electrode assembly being accommodated in the accommodating chamber. The electrode assembly includes a plurality of electrode units, the plurality of electrode units being stacked in an axial direction of the accommodating chamber. The top cover assembly includes a top cover plate, a first electrode terminal and a second electrode terminal, the top cover plate being connected to the housing and located on a side of the electrode assembly in the axial direction, and the first electrode terminal and the second electrode terminal both protruding from the top cover plate and being electrically connected to the electrode assembly.

Disclosed are a secondary battery, a battery module and an electric vehicle. The secondary battery includes an electrode assembly, a housing and a top cover assembly. The housing has an accommodating chamber, the accommodating chamber having an opening, and the electrode assembly being accommodated in the accommodating chamber. The electrode assembly includes a plurality of electrode units, the plurality of electrode units being stacked in an axial direction of the accommodating chamber. The top cover assembly includes a top cover plate, a first electrode terminal and a second electrode terminal, the top cover plate being connected to the housing and located on a side of the electrode assembly in the axial direction, and the first electrode terminal and the second electrode terminal both protruding from the top cover plate and being electrically connected to the electrode assembly.

A battery is provided that suppresses the occurrence of an internal short circuit due to a turned-up portion generated in a positive electrode. A secondary battery includes an electrode wound body, a positive electrode current collector plate, and an outer package can. The electrode wound body includes a positive electrode having a band shape and a negative electrode having a band shape, the positive electrode and the negative electrode being in a stacked arrangement with a separator interposed therebetween, and being wound. The outer package can contains the electrode wound body and the positive electrode current collector plate. The positive electrode includes a positive electrode active material covered part in which a positive electrode foil is covered with a positive electrode active material layer, and a positive electrode active material uncovered part. The secondary battery includes a flat surface formed by the positive electrode active material uncovered part that protrudes from one end of the electrode wound body being bent toward a central axis of the electrode wound body and portions of the positive electrode active material uncovered part overlapping each other. The flat surface is joined to the positive electrode current collector plate. The positive electrode active material uncovered part has a cutout at one end on an outer periphery side of the electrode wound body.