A battery module includes a first battery cell and a second battery cell respectively having a positive electrode lead and a negative electrode lead and connected to each other in series; and a short circuit inducing member having one longitudinal side interposed between the negative electrode lead of the first battery cell and the positive electrode lead of the second battery cell and the other longitudinal side located between the positive electrode lead of the first battery cell and the negative electrode lead of the second battery cell. When a potential difference between the negative electrode lead of the first battery cell and the positive electrode lead of the second battery cell increases over a reference value, the other longitudinal side of the short circuit inducing member makes flexural deformation toward the negative electrode lead of the second battery cell to come into contact with the negative electrode lead.

A battery protection circuit includes: a plurality of pack terminals configured to connect a battery module to an external device; a first fuse element located on a current path between the battery module and the pack terminals to block a current flow between the battery module and the pack terminals depending on a voltage applied to a control terminal thereof; a first integrated circuit configured to include a first input terminal and control a voltage outputted to the control terminal of the first fuse element depending on a voltage applied to the first input terminal; and a plurality of thermistors connected in series between a positive electrode of the battery module and a first input terminal of the first integrated circuit and having resistance that is varied depending on a temperature of a corresponding cell among a plurality of cells constituting the battery module.

A battery module and a manufacturing method therefor are provided. The battery module includes a pair of cylindrical battery cells, a pair of PTC elements at one side of the pair of battery cells, a connection member at an opposite side of the pair of cylindrical battery cells from the one side of the pair of cylindrical battery cells, and a connector having four wires connected to a single connection terminal and configured to electrically connect an external system and the pair of cylindrical battery cells via the connection terminal is provided.

A secondary battery includes an electrode assembly including a first electrode plate including a first electrode tab, a second electrode plate including a second electrode tab, and a separator interposed between the first electrode plate and the second electrode plate, a case accommodating the electrode assembly, and a cap assembly covering a top portion of the case. Any one of the first electrode tab and the second electrode tab includes a multi-layer clad electrode tab including two copper (Cu) layers.

A lithium ion secondary battery that includes a positive electrode, a negative electrode, a separator, a nonaqueous electrolytic solution, and a PTC layer between a positive electrode mixture layer and a positive electrode current collector and/or between a negative electrode mixture layer and a negative electrode current collector, the PTC layer having a positive temperature coefficient of resistance. The PTC layer contains nonconductive filler particles, and the electronic resistance at 120 C. is equal to or more than 100 times the electronic resistance at room temperature.

A battery pack is provided for use with a power tool. The battery pack includes a housing and a plurality of battery cells connected in series within the housing, such that an inter-cell node is defined between each pair of adjacent battery cells. A plurality of terminals is at least partially exposed outside of the housing for coupling the battery cells to at least one of a power tool or a battery charger. The plurality of terminals include a positive terminal, a negative terminal and one or more inter-cell terminals, where at least one of the inter-cell terminals is electrically coupled via a positive temperature coefficient thermistor to one of the inter-cell nodes.

A cylindrical secondary battery includes: an electrode assembly including a first electrode plate, a separator, and a second electrode plate; a case accommodating the electrode assembly and electrically connected to the second electrode plate; a terminal passing through a lower surface of the case and electrically connected to the first electrode plate; and a cap plate sealing an upper end portion of the case and having a vent. The vent is a thinner portion of the cap plate than other regions thereof and has a central notch having a ring shape and being at a central portion of the cap plate and an inner peripheral notch having a line shape extending from the central notch toward an edge of the cap plate.

The invention provides a bus-bar assembly, a power battery over-load protection system and method, as well as a power battery assembly, wherein the bus-bar assembly comprises a first connection arm having one or more connection ends so as to be connected to an upstream battery cell; a second connection arm having one or more connection ends so as to be connected to a downstream battery cell; and a PTC unit connected between the first connection arm and the second connection arm. The bus-bar assembly, the over-load protection system, the power battery assembly and the vehicle or the like according to the invention has better safety and stability.

An electrical breaker responsive to a fault condition is disclosed. A thermally-activated switch can be disposed between a first terminal and second and third terminals of the breaker. The switch can have a normal operating condition in which the first terminal is electrically connected to the second terminal. The switch can have a fault condition in which the first terminal is electrically connected to both the second terminal and the third terminal, causing a majority of the current to flow between the first terminal and the third terminal and a minority of the current to flow between the first terminal and the second terminal. The breaker can include a positive temperature coefficient (PTC) resistor between the first terminal and one of the second and third terminals. The thermally-activated switch can be integrated into a variety of structures, for example, a battery pack which can house one or more cells.

A battery is provided. The battery includes a positive electrode including a positive electrode active material layer provided on a positive electrode current collector; a negative electrode; and a separator at least including a porous film, wherein the porous film has a porosity [%] and an air permeability t [sec/100 cc] which satisfy formulae of:
t=aLn()4.02a+100 and 1.871010S.sup.4.96a40
wherein S is the area density of the positive electrode active material layer [mg/cm2] and Ln is natural logarithm.