A secondary battery includes a battery element including a positive electrode, a negative electrode, and an electrolytic solution, a housing member configured to accommodate the battery element, and a safety valve mechanism attached to the housing member. The safety valve mechanism includes a valve member including an opening valve portion configured to be opened; and an opening member including a plurality of opening portions radially arranged in a region opposed to the opening valve portion from a center of the region as a base point, and a plurality of protrusion portions radially arranged in a region outside the plurality of opening portions from the center and the plurality of protrusion portions protrude toward the plurality of opening portions. A number of the opening portions and a number of the protrusion portions are equal to each other, and each of the plurality of opening portions and each of the plurality of protrusion portions are opposed to each other in a direction toward the center.

A battery pack includes: battery cells; and a measurement circuit unit to measure temperature information of the battery cells, the measurement circuit unit including: a first measurement circuit unit including a first type temperature measurement element; and a second measurement circuit unit including a second type temperature measurement element having a different characteristic of a resistance change according to a temperature change from that of the first type temperature measurement element. The first measurement circuit unit and the second measurement circuit unit are on a common base substrate, or on different individual base substrates from each other.

A flexible sheet of positive temperature coefficient (PTC) material formed of a polymer resin and a conductive filler, the sheet of PTC material having a thickness in a range of 10 μm to 100 μm. A method for forming the flexible sheet of positive temperature coefficient material may include preparing a PTC ink from a polymer resin, a conductive filler, and a solvent, applying the PTC ink to a substrate, pulling a blade over the PTC ink to create a uniformly thick layer of the PTC ink on the substrate, and allowing the PTC ink to dry so that the solvent evaporates and leaves a solid layer of PTC material on the substrate.

A lithium secondary battery pack of the present invention includes: a lithium secondary battery including an electrode body formed of a positive electrode and a negative electrode facing each other and a separator interposed therebetween, and a non-aqueous electrolyte; a PTC element; and a protection circuit including a field effect transistor. The lithium secondary battery has an energy density per volume of 450 Wh/L or more, the lithium secondary battery has a current density of 3.0 mA/cm.sup.2 or less, and a relational expression (1) and a relational expression (2) below are established where A (mΩ) is an impedance of the lithium secondary battery and B (mΩ) is an impedance of the entire circuit unit of the lithium secondary battery pack excepting the impedance A (mΩ) of the lithium secondary battery:
A≤50 mΩ  (1)
B/A≤1  (2).

Embodiments described herein relate to electrodes and electrochemical cells with positive temperature coefficient coatings and methods of producing the same. In some embodiments, an electrode can include a layer of a film material, a positive temperature coefficient (PTC) coating disposed in the layer of film material. The PTC material resists a flow of current through at least a portion of the PTC material when a temperature of the at least a portion of the PTC material exceeds a threshold value. The electrode further includes an electrode material disposed on the PTC material. In some embodiments, the electrode can further include an electrode tab coupled to the PTC material and the electrode film. In some embodiments, the PTC material can include a conductive polymer. In some embodiments, the electrode material can include a semi-solid and/or a binderless electrode material.

The present invention relates to a positive electrode plate and an electrochemical device. The positive electrode plate comprises a current collector, a positive active material layer and a safety coating disposed between the current collector and the positive active material layer, and wherein the safety coating comprises a polymer matrix, a conductive material and an inorganic filler and wherein when the safety coating and the positive active material layer are collectively referred as a film layer, the film layer has an elongation of 30% or more and wherein the polymer matrix of the safety coating is fluorinated polyolefin and/or chlorinated polyolefin having a crosslinked structure. The positive electrode plate may improve the safety performance during nail penetration of the electrochemical device such as capacitor, primary battery or secondary battery and the like.

A battery module includes: an all-solid-state battery having a voltage exceeding 0 V; a semiconductor element; a PTC element; and a circuit board, wherein the all-solid-state battery, the semiconductor element, and the PTC element are solder-bonded to the circuit board, the all-solid-state battery has a positive electrode terminal and a negative electrode terminal, the semiconductor element is electrically connected between the positive electrode terminal and the negative electrode terminal, and the PTC element is connected in series between the positive electrode terminal or the negative electrode terminal and the semiconductor element.

The breaker is provided with a fixed contact, a movable piece having an elastic portion and a movable contact, a thermally-actuated element deforming with a change in the temperature so as to shift the movable piece from a conduction state to a cut-off state, a case main body housing the movable piece and the thermally-actuated element, a lid member attached to the case main body, and a plate-shaped cover piece embedded in the lid member. The case main body is provided with a first fixing surface fixed to the lid member, and the lid member is provided with a second fixing surface fixed to the case main body. The second fixing surface is provided with a protruding portion protruding toward the first fixing surface, and the protruding portion and the cover piece are overlapped with each other in the plan view as viewed in the thickness direction of the cover piece.

A battery pack includes at least one battery cell; a protection circuit module electrically connected to the at least one battery cell; and a thermocompression bonding layer, the thermocompression bonding layer providing a disconnectable electrical connection between an electrode tab of the at least one battery cell and a connection tab of the protection circuit module, wherein the thermocompression bonding layer includes conductive particles and an insulating composite resin layer, the insulating composite resin layer surrounds the conductive particles, and the insulating composite resin layer includes at least one first resin layer and at least one second resin layer, the at least one first resin layer being different from the at least one second resin layer.

A battery pack includes a cell block including battery cells electrically connected to each other, the cell block having a pair of long sides and a pair of short sides which surround lateral surfaces of the battery cells and are tangent to the lateral surfaces of the battery cells, and a flexible wiring surrounding the cell block in a direction parallel to the pair of long sides of the cell block, the flexible wiring including sensors to detect state information from the battery cells.