An end cover assembly includes: an end cover with a through hole for injecting electrolyte and a first clamping portion, wherein the first clamping portion is disposed along a circumferential direction of the through hole and is located on one side of the end cover away from an interior of the battery cell; a sealing ring for sealing the through hole; and a pressure relief device covering at least part of the sealing ring and closing the through hole; wherein the pressure relief device includes a second clamping portion, and is rotatable such that when the pressure relief device is rotated to a first position, the second clamping portion is clamped with the first clamping portion; and when the pressure relief device is rotated to a second position, the second clamping portion is disengaged from the first clamping portion.

An automatic and passive battery fluid maintenance system maintains the fluid levels in a battery system by replenishing water as the water is lost from the battery. A reservoir is used to contain a volume of fluid and is mounted above the batteries. Fluid from the reservoir flows into a distribution manifold through a flow regulator. From the manifold the fluid is distributed to a vent plug at each battery. The vent plugs are configured to control create a backpressure in the fluid line when the battery fluid level is at an optimum level. As a result of the backpressure, fluid does not flow into the battery through the vent plug. When the fluid in the battery drops below the optimum level, the backpressure is reduced, allowing water to flow until the fluid level of the battery again is at the optimum level.

An automatic and passive battery fluid maintenance system maintains the fluid levels in a battery system by replenishing water as the water is lost from the battery. A reservoir is used to contain a volume of fluid and is mounted above the batteries. Fluid from the reservoir flows into a distribution manifold through a flow regulator. From the manifold the fluid is distributed to a vent plug at each battery. The vent plugs are configured to control create a backpressure in the fluid line when the battery fluid level is at an optimum level. As a result of the backpressure, fluid does not flow into the battery through the vent plug. When the fluid in the battery drops below the optimum level, the backpressure is reduced, allowing water to flow until the fluid level of the battery again is at the optimum level.

An energy storage device includes a container that accommodates an electrode assembly, and the container includes, on a surface of the container as viewed from a thickness direction of the container, a first recessed portion in a portion of a corner portion of the surface or in a portion of a side portion of the surface. The first recessed portion penetrates in the thickness direction, and a gas release valve is disposed in the first recessed portion.

The disclosure provides a housing for a battery cell, a battery cell, a battery, and an electric device. A containment chamber is formed inside the housing for the battery cell for containing electrolyte, the housing includes a gas withdrawal structure, through which gases in the containment chamber can be withdrawn, and the gas withdrawal structure includes: a gas withdrawal hole arranged on the housing; and a liquid retaining structure cooperating with the gas withdrawal hole, arranged in the containment chamber, the liquid retaining structure is configured to prevent the electrolyte from being withdrawn from the gas withdrawal hole, where the liquid retaining structure includes: a first body, which is a hollow structure; and a liquid stopper arranged in the first body.

The disclosure provides a housing for a battery cell, a battery cell, a battery, and an electric device. A containment chamber is formed inside the housing for the battery cell for containing electrolyte, the housing includes a gas withdrawal structure, through which gases in the containment chamber can be withdrawn, and the gas withdrawal structure includes: a gas withdrawal hole arranged on the housing; and a liquid retaining structure cooperating with the gas withdrawal hole, arranged in the containment chamber, the liquid retaining structure is configured to prevent the electrolyte from being withdrawn from the gas withdrawal hole, where the liquid retaining structure includes: a first body, which is a hollow structure; and a liquid stopper arranged in the first body.

A secondary battery is configured such that a vent recess is provided in a rivet configured to seal an electrolyte injection port of a case and the vent recess is fractured if the internal pressure of the case increases, whereby internal gas is discharged, and therefore the secondary battery is made safer. The secondary battery includes an electrode assembly having a first electrode plate and a second electrode plate, a case in which the electrode assembly is received, and a rivet extending through a side of the case. The rivet includes vent recess, and a region of the rivet having the vent recess is thinner than other regions of the rivet.

A secondary battery is configured such that a vent recess is provided in a rivet configured to seal an electrolyte injection port of a case and the vent recess is fractured if the internal pressure of the case increases, whereby internal gas is discharged, and therefore the secondary battery is made safer. The secondary battery includes an electrode assembly having a first electrode plate and a second electrode plate, a case in which the electrode assembly is received, and a rivet extending through a side of the case. The rivet includes vent recess, and a region of the rivet having the vent recess is thinner than other regions of the rivet.

A battery cell may include a contacting wall surface with an expanded inner diameter at an open end of a sidewall of a battery can of the battery cell. The cap covering the open end includes a press-fitted contacting surface portion in contact with the inner circumferential surface of the contacting wall surface portion, and an electrode connecting part connected to an electrode tab of an electrode assembly accommodated in the battery can. The press-fitting depth of the cap into the battery can is regulated by the electrode connecting part of the cap and the electrode tab of the electrode assembly. The contacting surface portion and the contacting wall surface portion are bonded and electrically connected by welding. A battery pack may include the battery cell, and a vehicle may include the battery pack.

A battery cell may include a contacting wall surface with an expanded inner diameter at an open end of a sidewall of a battery can of the battery cell. The cap covering the open end includes a press-fitted contacting surface portion in contact with the inner circumferential surface of the contacting wall surface portion, and an electrode connecting part connected to an electrode tab of an electrode assembly accommodated in the battery can. The press-fitting depth of the cap into the battery can is regulated by the electrode connecting part of the cap and the electrode tab of the electrode assembly. The contacting surface portion and the contacting wall surface portion are bonded and electrically connected by welding. A battery pack may include the battery cell, and a vehicle may include the battery pack.