Abstract: In a lithium ion secondary battery, a lithium-nickel-containing composite oxide that contains lithium and nickel is used as a positive electrode active material, and a negative electrode active material having a melting temperature of 1200° C. or less in a lithium-absorbed state is included in a negative electrode active material layer. By configuring as above, in the lithium ion secondary battery, it is possible to achieve higher capacity, higher output, and longer life, as well as further improved safety, and particularly in a nail penetration test, to suppress the heat generation due to internal short circuit and to reliably prevent the occurrence of thermal runaway.

Abstract: A battery includes an electrode assembly including a first electrode and a second electrode, a non-aqueous electrolyte, a battery case, a first lead connecting the first electrode with a bottom of the battery case, a seal member sealing an opening of the battery case, and a second lead connecting the second electrode with the seal member. At least one of the first lead and the second lead has a high resistant portion that has a higher resistance than the other portions per unit length. The high resistant portion is disposed at a position of the first lead closer to the first electrode than the portion connected to the bottom of the battery case or at a position of the second lead closer to the second electrode than the portion connected to the seal member. The high resistant portion is in contact with the battery case or the seal member.

Abstract: A battery includes an electrode group, a case, a sealing member, and a mesh portion. The electrode group includes a positive electrode, a negative electrode opposing the positive electrode, an electrolyte interposed between the positive electrode and the negative electrode. The case has an opening and contains the electrode group. The sealing member closes the opening of the case. The mesh portion is provided so as to face an exhaust hole formed in at least one of the case and the sealing member.

Abstract: In a lithium ion secondary battery including a flat-plate electrode assembly which is configured by stacking the positive electrode, the separator, and the negative electrode in the thickness direction thereof, each of the positive electrode and the negative electrode includes a current collector and an active material layer. Each of the current collector includes a substantially rectangular current collector body, a heat radiating portion, and a lead portion, and the heat radiating portions are projected toward the outside of the electrode assembly so as not to overlap with each other in the thickness direction of the electrode assembly. In this way, heat caused inside the lithium ion secondary battery can be diffused efficiently to the outside, and safety of the lithium ion secondary battery can be further increased, without complicating the battery structure and decreasing mechanical strength of the battery.

Abstract: A lithium ion secondary battery includes a negative electrode that is shaped like waves in a section in the thickness direction. In the negative electrode, the ratio t1/t0 of the largest thickness t1 to the smallest thickness t0 is from 1.2 to 3.0. The negative electrode includes a thin-film negative electrode active material layer in which the ratio A/B of the volume A in a charged state to the volume B in a discharged state is 1.2 or more. The lithium ion secondary battery has high capacity, high power, long life, and improved safety. In particular, heat generation due to an internal short-circuit is significantly suppressed in a nail penetration test.

Abstract: A sealed cell with a film outer casing body having a flat electrode body is prevented from short circuiting damage due to impacts. The flat electrode body has first and second electrodes and a separator therebetween, which are wound into a flat shape having first and second flat side surface R portions. The first electrode is the outermost surface of the electrode body. An insulation film is provided between the outermost portion of the first electrode and a portion of the second electrode immediately inside the outermost portion, and between the portion of the second electrode and another portion of the first electrode immediately inside the portion of the second electrode.

Abstract: A battery includes an electrically-conductive battery can (1) for accommodating a spirally-wound electrode assembly (3) in which an electrolyte solution is impregnated. The battery can has an open end and a closed end, and to the open end, an electrically-conductive sealing plate (5) is fixed being insulated from the battery can (1). A positive electrode (31) and a negative electrode (33) project from respective opposing ends of the spirally-wound electrode assembly (3), and a positive electrode current collector plate (4) and a negative electrode current collector plate (2) are joined to the respective projecting edges of the electrodes (31), (33). Electrically-conductive leads (45), (46) connect the positive electrode current collector plate (4) and the sealing plate (5) together. The negative electrode current collector plate (2) and the battery can (1) are electrically connected to each other.

Abstract: The present invention prevents a cell with a film outer casing body from suffering internal short-circuiting caused by dropping impacts. This is accomplished by a sealed cell with a film outer casing body having a flat electrode body. The flat electrode body has first and second electrodes and a separator therebetween, which are wound into a flat shape having first and second flat side surface R portions. The first electrode is the outermost surface of the electrode body. An insulation member is provided on the electrode body to completely cover the lower edge and/or upper edge of the first flat side surface R portion. Specifically, the insulation film is provided between the outermost portion of the first electrode and a portion of the second electrode immediately inside the outermost portion, and between the portion of the second electrode and another portion of the first electrode immediately inside the portion of the second electrode.