The present disclosure is directed to an improved energy storage system. The energy storage system includes an energy storage device having positive and negative terminals, a battery management system configured to monitor and control the energy storage device, and a power connector configured to electrically couple the battery management system with the energy storage device. The power connector includes a housing and positive and negative bus bars, each containing a positive and negative interface pin, respectively. The interface pins are operatively coupled to the positive and negative terminals of the energy storage device to form a power connection. The housing contains separate, opposing side walls defining an open passageway therebetween. Thus, the open passageway provides air cooling across the power connection.

A motor vehicle traction battery assembly has a battery control unit and battery modules. Each battery module includes a degassing opening. A plurality of busbars is arranged in a rail tunnel, to which the battery modules are electrically connected. The rail tunnel is fluidly shielded by a tunnel lid. The battery control unit includes an interior having a gas-tight battery control unit housing body in which connection rails and an electronic battery controller are accommodated. The electrical connections between the busbars and the connection rails are formed by vertical contact bodies, which pass through a connection opening lying in the horizontal plane between the rail tunnel and the battery control unit interior. The connection opening is fluidly sealed by a sealing wall, through which the contact bodies pass in a fluid-tight manner.

Disclosed is a battery module manufacturing method for welding a busbar and an electrode lead included in a battery cell. The method includes bonding the busbar and a filler wire by laser welding. The method also includes bonding the electrode lead and the filler wire by laser welding after the bonding the busbar and the filler wire.

Disclosed is a compact secondary battery module, which includes a cartridge assembly having a plurality of cartridges stacked while accommodating cells, respectively, so that a plurality of lead welding portions where a first lead and a second lead of adjacent cells overlap with each other are located at a cartridge sidewall with a predetermined pattern; and a sensing housing having a plurality of bus bars located and welded corresponding to the lead welding portions, respectively, the sensing housing being capable of being arranged at a side of the cartridge assembly, wherein when the sensing housing is coupled to the cartridge assembly, the first lead, the second lead and the bus bar are located in order from the sidewall of the cartridge in an outer direction and welded from the bus bar.

To improve the safety of a secondary battery, the present disclosure provides a secondary battery including: a plurality of battery cells each including a case and an electrode assembly accommodated in the case; a plurality of first bus bars electrically connected to the plurality of battery cells and having a first thickness, the plurality of first bus bars being apart from each other with a predetermined gap therebetween; and a second bus bar arranged above the plurality of first bus bars and electrically connected to the plurality of first bus bars, the second bus bar having a second thickness greater than the first thickness.

To improve the safety of a secondary battery, the present disclosure provides a secondary battery including: a plurality of battery cells each including a case and an electrode assembly accommodated in the case; a plurality of first bus bars electrically connected to the plurality of battery cells and having a first thickness, the plurality of first bus bars being apart from each other with a predetermined gap therebetween; and a second bus bar arranged above the plurality of first bus bars and electrically connected to the plurality of first bus bars, the second bus bar having a second thickness greater than the first thickness.

A battery module includes cylindrical battery cells, a module housing, and a bus bar. The bus bar includes a main body portion that is positioned at a top or a bottom of the plurality of cylindrical battery cells and has a plate shape having upper and lower surfaces that are broader than a lateral surface of the main body portion in a horizontal direction; and a contact portion that is configured to electrically contact and be connected to an electrode terminal formed in one of the plurality of cylindrical battery cells, extends and protrudes from the main body portion in a horizontal direction, is stepped from the main body portion in a direction toward where the electrode terminal is positioned, and includes a branched structure bifurcated in two directions with respect to a direction in which the contact portion extends and protrudes from the main body portion.

A battery module includes cylindrical battery cells, a module housing, and a bus bar. The bus bar includes a main body portion that is positioned at a top or a bottom of the plurality of cylindrical battery cells and has a plate shape having upper and lower surfaces that are broader than a lateral surface of the main body portion in a horizontal direction; and a contact portion that is configured to electrically contact and be connected to an electrode terminal formed in one of the plurality of cylindrical battery cells, extends and protrudes from the main body portion in a horizontal direction, is stepped from the main body portion in a direction toward where the electrode terminal is positioned, and includes a branched structure bifurcated in two directions with respect to a direction in which the contact portion extends and protrudes from the main body portion.

A battery system includes a battery block having a plurality of square battery cells (1) stacked in one direction, parallel connection bus bars (5X), insulating plate (7), and lid plate (8) fixed to insulating plate (7). Each square battery cell (1) has a discharge port provided with discharge valve (14) and a sealing plate provided with positive and negative electrode terminals via an insulating material. Parallel connection bus bars (5X) are connected to the electrode terminals to connect some or all of square battery cells (1) in parallel. Insulating plate (7) is disposed on the surfaces of sealing plates of the plurality of square battery cells (1) and includes passing portions having openings provided at positions corresponding to the discharge ports to pass the exhaust gas ejected from the discharge ports and pressing portions (22) disposed between parallel-connection bus bars (5X) and the sealing plates. Lid plate (8) faces discharge ports facing the openings of the passing portions.

A battery system includes a battery block having a plurality of square battery cells (1) stacked in one direction, parallel connection bus bars (5X), insulating plate (7), and lid plate (8) fixed to insulating plate (7). Each square battery cell (1) has a discharge port provided with discharge valve (14) and a sealing plate provided with positive and negative electrode terminals via an insulating material. Parallel connection bus bars (5X) are connected to the electrode terminals to connect some or all of square battery cells (1) in parallel. Insulating plate (7) is disposed on the surfaces of sealing plates of the plurality of square battery cells (1) and includes passing portions having openings provided at positions corresponding to the discharge ports to pass the exhaust gas ejected from the discharge ports and pressing portions (22) disposed between parallel-connection bus bars (5X) and the sealing plates. Lid plate (8) faces discharge ports facing the openings of the passing portions.