A protection device comprises a resin base, PTC component, bimetal component, arm and upper plate which are housed in a resin housing wherein the base includes a terminal integrated with the base by insert molding. A resin cover is formed by insert molding to cover the PTC component, bimetal component, arm and upper plate which are superposed in this order over the terminal within a space in the base. The space in the resin base is substantially closed by the upper plate, the base and the cover are integrally bonded to define the resin housing, the terminal and the arm are electrically connected in series in a normal state, and in an abnormal state where the bimetal component is activated, the terminal and the arm are electrically cut off, while the terminal, PTC component, bimetal component, and arm are electrically connected in series in this order.

A novel heater is disclosed for a temperature sensitive actuator. The heater is a polymeric positive temperature coefficient (PPTC) device consisting of conductive filler and semi-crystalline polymer. The PPTC heater is strategically designed to have a predetermined self-regulation temperature suited to whatever application utilizes the heater. Physical characteristics of the PPTC heater, such as gap width and thickness, enable the current flow through the heater to be strategically controlled.

An over-current protection device includes first and second electrodes and a positive temperature coefficient (PTC) multilayered structure disposed between the first and second electrodes. The PTC multilayered structure includes a first polymer layer that is bonded to the first electrode, an intermediate layered unit that is bonded to said first polymer layer and that includes a second polymer layer, a third polymer layer that is bonded to and disposed between the intermediate layered unit and the second electrode. The first, second and third polymer layers respectively have first, second and third volume resistances, the second volume resistance being higher than the first and third volume resistances.

A novel heater is disclosed for a temperature sensitive actuator. The heater is a polymeric positive temperature coefficient (PPTC) device consisting of conductive filler and semi-crystalline polymer. The PPTC heater is strategically designed to have a predetermined self-regulation temperature suited to whatever application utilizes the heater. Physical characteristics of the PPTC heater, such as gap width and thickness, enable the current flow through the heater to be strategically controlled.

A PPTC over-current protection device includes: a first PPTC component that has a first metal foil layer and a first PTC element including a first polymer matrix, the first metal foil layer being bonded to the first polymer matrix; and a second PPTC component that has a second metal foil layer and a second PTC element including a second polymer matrix. The second metal foil layer is bonded to the second polymer matrix. The first and second PPTC components are stacked one above the other and are bonded to each other to form a stack with the first and second polymer matrices being bonded to each other by interfusion-bonding.

Disclosed herein is a method of manufacturing a secondary battery electrode containing a positive temperature coefficient (PTC) material, the method including (a) applying first slurry including a first mixture and a solvent mixed with each other to one surface of a planar current collector to generate a PTC material after drying, (b) applying second slurry including a second mixture, including an electrode active material, and a solvent mixed with each other to the first slurry applied to the current collector, which is in a non-dried state, and (c) drying the first slurry and the second slurry applied to the current collector.

A method for manufacturing a sheet of positive temperature coefficient (PTC) material includes providing a PTC material, grinding the PTC material into a powder, and inserting the ground PTC material into a press. The ground PTC material is compressed within the press until the PTC material defines a planar shape. The PTC material is then removed from the press to thereby provide a PTC sheet.

Provided are a current collector which has an excellent high-rate property and exerts a sufficient safety function when employed in a secondary battery or a capacitor, as well as an electrode, a secondary battery or a capacitor in which said current collector is employed. According to the invention, a current collector is provided which comprises: metal foil; and a conductive layer with a film thickness of 0.1 μm to 10 μm formed on a surface of said metal foil. Here, said conductive layer includes a conductive material and a binder material. A melting point of said binder material is 80° C. to 150° C. Further, said binder material shows, in differential scanning calorimetry (DSC) in a range from room temperature to 200° C., one or more endothermic peaks in the heating-up process. In a case where said binder material shows two or more endothermic peaks, each difference between said peaks is 15° C. or more. Moreover, said binder material shows one or more exothermic peaks in the cooling-down process. In a case where said binder material shows only one exothermic peak, said exothermic peak falls within a range of 50 to 120° C., and a width at half maximum of said exothermic peak is 10° C. or less. On the other hand, in a case where said binder material shows two or more exothermic peaks, a maximum exothermic peak among said exothermic peaks falls within a range of 50 to 120° C., and a width at half maximum of said exothermic peak is 10° C. or less.

A PTC device as well as an electrical device such as a battery pack or a dry-cell type secondary cell containing a PTC device and a secondary cell is made more compact. The PTC device includes (1) a PTC component including a laminar polymer PTC element having an electrically conductive filler and a polymer material, and a metal electrode disposed on a surface of each side of the polymer PTC element; and (2) a lead positioned at least in part on the metal electrode of the PTC component, and connected to the metal electrode by an electrically conductive material An exposed part of the electrically conductive material is covered by a protective member including a polypropylene resin, a nylon resin or an epoxy resin.

Disclosed here is a method for sensing temperature-dependent electrical switching response, comprising: exposing a polymer-carbon composite to a temperature change, wherein the polymer-carbon composite comprises (a) a semi-conductive or conductive carbon network intercalated with (b) a polymer matrix, wherein the carbon network comprises at least one covalently bonded carbon material, and wherein the polymer matrix comprises at least one polymer having a net electron withdrawing character and adapted to apply a gating effect on the conductive carbon; and detecting a change in electrical conductivity of the polymer-carbon composite of at least three orders of magnitude. Also disclosed is a smart switching device comprising the polymer-carbon composite and a switch triggerable by an increase or decrease in electrical conductivity of the polymer-carbon composite of at least three orders or magnitude.