A technical problem to be solved according to an embodiment of the present invention is to provide a cylindrical secondary battery which can prevent components thereof from being deformed during manufacturing processes or in use. To this end, an embodiment of the present invention provides a cylindrical secondary battery comprising: a cylindrical can; an electrode assembly received in the cylindrical can; and a cap assembly covering the cylindrical can to seal the electrode assembly, wherein the cap assembly comprises a cap-up, a cap-down below the cap-up, and a safety vent between the cap-up and the cap-down, and the contact ratio between the safety vent and the cap-down ranges from 60% to 100%.

A degassing unit for an electronics housing has a base body with gas passage opening and is connectable fluid-tightly to a rim of a pressure compensation opening of the electronics housing. A semipermeable membrane for covering the pressure compensation opening enables passage of gaseous media from an environment into the electronics housing interior and vice versa but prevents passage of liquids and solids. A membrane support device, arranged at an interior side of the base body facing the electronics housing interior, engages across the gas passage opening and is positioned at a first distance to the semipermeable membrane. A separation lattice with lattice openings is arranged at the interior side of the base body at a second larger distance to the semipermeable membrane and completely engages across the gas passage opening. A surface area spanned by the separation lattice is larger than a cross section of the gas passage opening.

A degassing system of a pouch for a secondary battery is provided. In the degassing system, after inhaling gas regardless of the size of a cell pocket, the gas may be processed, and the convenience of work may be increased by setting the period of degassing time or the amount of gas to be discharged according to the size of a pouch, and an abnormality in a suction line for degassing may be automatically detected according to a comparison value by comparing the amount of discharged gas with a reference value preset by each pouch size.

A degassing unit to be connected fluid-tightly to a pressure compensation opening of an electronics housing has a base body with gas passage opening. A semipermeable membrane, fastened fluid-tightly to a membrane carrier, allows gaseous media to pass from an environment into the electronics housing and in reverse but prevents passage of liquid media and solids. In normal operation, the membrane covers the gas passage opening. An axial seal circumferentially extends about the gas passage opening. The membrane carrier is moveable relative to the base body and, in normal operation, is pressed by axial force seal-tightly against the axial seal. The membrane carrier, when a predetermined pressure difference between housing interior and environment is surpassed, lifts off the base body to release an emergency degassing opening surrounding the membrane. The axial seal is a lip seal and made of a material softer than a material of the membrane carrier.

A degassing unit to be connected fluid-tightly to a pressure compensation opening of an electronics housing has a base body with gas passage opening. A semipermeable membrane, fastened fluid-tightly to a membrane carrier, allows gaseous media to pass from an environment into the electronics housing and in reverse but prevents passage of liquid media and solids. In normal operation, the membrane covers the gas passage opening. An axial seal circumferentially extends about the gas passage opening. The membrane carrier is moveable relative to the base body and, in normal operation, is pressed by axial force seal-tightly against the axial seal. The membrane carrier, when a predetermined pressure difference between housing interior and environment is surpassed, lifts off the base body to release an emergency degassing opening surrounding the membrane. The axial seal is a lip seal and made of a material softer than a material of the membrane carrier.

A system includes a vent housing configured to be installed on a lower housing of a battery module at a first side of the vent housing. The vent housing has a main body having an opening on a second side of the vent housing and an internal chamber coupled to the opening. The internal chamber includes a first wall having an internal burst vent configured to open at a first pressure threshold and a second wall having a ventilation vent comprising a gas-selective permeability layer.

A system includes a vent housing configured to be installed on a lower housing of a battery module at a first side of the vent housing. The vent housing has a main body having an opening on a second side of the vent housing and an internal chamber coupled to the opening. The internal chamber includes a first wall having an internal burst vent configured to open at a first pressure threshold and a second wall having a ventilation vent comprising a gas-selective permeability layer.

A battery module includes a battery cell stack in which a plurality of battery cells are stacked; a module frame that houses the battery cell stack; and a first end plate and a second end plate each covering a front surface and a rear surface of the battery cell stack, wherein a venting hole is formed in at least one of the module frame, the first end plate or the second end plate. A venting unit for guiding a discharge path of gas or flame discharged from the venting hole is located on one surface of the module frame, and the venting unit is mounted so as to cover the venting hole.

A battery module includes a battery cell stack in which a plurality of battery cells are stacked; a module frame that houses the battery cell stack; and a first end plate and a second end plate each covering a front surface and a rear surface of the battery cell stack, wherein a venting hole is formed in at least one of the module frame, the first end plate or the second end plate. A venting unit for guiding a discharge path of gas or flame discharged from the venting hole is located on one surface of the module frame, and the venting unit is mounted so as to cover the venting hole.

The invention relates to an energy storage system for a vehicle, in particular a starter battery for a vehicle, having a plurality of energy storage cells for providing and/or storing electric energy and a housing which has a plurality of wall elements that delimit the interior of the housing. The housing is designed to receive the plurality of energy storage cells in the interior of the housing. A plurality of separating walls are arranged in the interior of the housing in order to divide the interior of the housing into a plurality of chambers, wherein each chamber is designed to receiving an energy storage cell. A fluidic connection is formed between the individual chambers, and a ventilation valve is arranged on one of the wall elements, preferably a cover element, of the housing in a respective region paired with the corresponding chamber. At least one of the ventilation valves is an active ventilation valve, and the remaining ventilation valves are blind closures.