Battery Cap Assembly Structure to Prevent Vent Piece Rupture
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Solution Overview
Problem
Secondary batteries experience excessive composite forces due to electrode assembly expansion, leading to vent piece rupture and reduced battery performance and life, as existing technologies fail to effectively manage expansion forces and prevent vent piece failure.
Innovation Solution
The secondary battery design includes a cap assembly with a recessed second inner surface on the vent piece, grooves on the cap plate, and an insulating member to distribute expansion forces, preventing vent piece rupture and ensuring even deformation, thereby reducing safety risks and extending battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode assembly is allowed to expand freely during charge/discharge processes, then the battery can maintain good electrochemical performance, but the expanding forces accumulate and form excessive composite force that presses the secondary batteries, leading to vent piece rupture and reduced battery life
Solution Approach 1:
The patent applies beforehand cushioning by providing a buffer structure between the electrode assembly and the vent piece. The buffer includes a buffer plate positioned between the electrode assembly and the vent piece, and buffer springs arranged between the buffer plate and the electrode assembly. These buffer springs are pre-compressed to generate a buffer force that counteracts the expansion force of the electrode assembly before it can cause damage to the vent piece, thereby preventing vent piece rupture while allowing normal expansion during charge/discharge cycles.
2Productivity
If the vent piece is positioned close to the electrode assembly to facilitate gas venting, then the venting function is improved, but the vent piece is more susceptible to rupture from expansion forces
Solution Approach 1:
The patent applies the intermediary principle by introducing a buffer plate and buffer springs as intermediary elements between the electrode assembly and the vent piece. The buffer plate serves as a mediator that transmits the expansion force to the buffer springs, which then convert this force into a controlled buffer force. This intermediary buffer structure allows the vent piece to remain positioned close to the electrode assembly for efficient gas venting, while simultaneously protecting the vent piece from direct exposure to excessive expansion forces that would cause rupture.
Data Source
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AI summary
The present invention provides a secondary battery and a battery module. The battery module includes secondary batteries arranged sequentially. The secondary battery includes an electrode assembly, a case and a cap assembly. The case has an accommodating cavity, and the electrode assembly is accommodated in the accommodating cavity. The electrode assembly comprises electrode units, and the electrode units are stacked in an axial direction of the accommodating cavity. The cap assembly comprises a cap plate and a vent piece, the cap plate is connected with the case and positioned at a side of the electrode assembly in the axial direction. The cap plate is provided with a through-hole, and the vent piece is connected with the cap plate and covers the through-hole. The cap plate has a first inner surface at a side close to the electrode assembly, the vent piece has a second inner surface at a side close to the electrode assembly, and a distance between the first inner surface and the electrode assembly is larger than a distance between the second inner surface and the electrode assembly. In the battery module, an arrange direction of the secondary batteries is perpendicular to the axial direction.