A secondary battery is disclosed. In one aspect, the secondary battery includes a case accommodating an electrode assembly, a cap plate sealing an opening of the case, an electrode terminal electrically connected to the electrode assembly and disposed over the cap, and an insulating member provided between the cap plate and the electrode terminal and configured to insulate the electrode terminal from the cap plate. The battery also includes a connection tab disposed over the electrode terminal, and a safety device having a portion positioned under the connection tab and electrically connected to the electrode terminal via the connection tab. The safety device has at least one of electric conductivity and thermal conductivity greater than that of the connection tab, and at least a part of the safety device is seated on the insulating member.

A battery housing can include a housing body defining a cavity sized and shaped to receive a cell for a battery, and a breaker coupled with the housing body. The battery housing can comprise a first electrical conductor at a first end portion of the housing body and electrically connected to the switch, the first electrical conductor configured to electrically connect to a first battery cell terminal of the cell. The battery housing can comprise a second electrical conductor at a second end portion of the housing body, the second electrical conductor configured to electrically connect to a second battery cell terminal of the cell to define a first electrical pathway between the first electrical conductor and the second electrical conductor. The battery housing can include a bypass conductor to define a second electrical pathway between the switch and the second electrical conductor.

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.

The circuit breaker is fabricated by an assembly step that makes a circuit breaker assembly with a moving contact metal plate, stationary contact metal plate, and bimetallic strip disposed in prescribed locations in an external case; and an anneal step that introduces the circuit breaker assembly made in the assembly step into an anneal oven, heats the circuit breaker assembly in the anneal oven and then cools it to anneal both the moving contact metal plate and the bimetallic strip and produce a heat-treated circuit breaker.

A breaker comprises: a first terminal piece on which a fixed contact is formed; a movable piece having a movable contact, for pressing the movable contact against the fixed contact so as to contact therewith; a thermally-actuated element deforming with a change in temperature and moving the movable piece so that the movable contact is separated from the fixed contact, and a second terminal piece electrically connected to the movable piece. The movable piece is provided, within a contact portion contacting with the second terminal piece, with a protrusion projecting toward the thermally-actuated element.

Disclosed are a safety device and a secondary battery using the same. The safety device includes a voltage sensitive heating device generating heat when a voltage difference between both ends thereof exceeds a predetermined voltage level and a temperature sensitive device having a reversible current ON/OFF function according to a temperature. The temperature sensitive device is coupled with the voltage sensitive heating device such that the temperature sensitive device detects the heat generated from the voltage sensitive heating device.

Battery system with overcharge and/or exhaustive-discharge protection, comprising at least one electrical energy store having a first pole which is electrically connected to a first electrode of the electrical energy store, having a second pole which is electrically connected to a second electrode of the electrical energy store, having a rapid-discharge unit for electrically discharging the electrical energy store having a first connection which is electrically connected to the first pole, having a second connection which is electrically connected to the second pole, characterized in that the battery system comprises a tripping unit for tripping the rapid-discharge unit.

A battery pack includes a plurality of battery modules including a first battery module and a second battery module; and a busbar electrically connecting the first battery module and the second battery module, wherein the first battery module or the second battery module includes a vent hole in a portion corresponding to a portion of the busbar.

An inter-device conduction member includes a conduction part having a first connecting portion that connects to an electrode terminal of one power storage device, a second connecting portion that connects to an electrode terminal of another power storage device, and an expected breaking portion that is located between the first connecting portion and the second connecting portion and is conductively connected with the first connecting portion and the second connecting portion, and a break inducing part configured to deform upon a temperature rise to a level equal to or higher than an operating temperature to break the expected breaking portion of the conduction part and make connection between the first connecting portion and the second connecting portion non-conductive.

The present disclosure relates to a battery pack and an operation method thereof. The battery pack includes a pack case, a plurality of cylindrical battery cells in the pack case, and a current breaking device in the pack case to connect the plurality of cylindrical battery cells and having a portion including a bimetal. The current breaking device includes a fixed end contacting an electrode terminal of the cylindrical battery cell, a free end contacting an electrode terminal of the surrounding cylindrical battery cell, and a flexible member configured to elastically press the free end toward the surrounding cylindrical battery cell. The battery pack may include a current breaking device using bimetal that is capable of quickly restoring a connection with a surrounding cylindrical battery cell when a state of a battery cell separated from the surroundings in case of an abnormal state thereof is recovered.