Battery Cap Assembly With Variable Thickness Fixing Member
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Solution Overview
Problem
Conventional cap assemblies for secondary batteries require numerous mechanical components, increasing costs and reducing reliability, and suffer from reduced energy density due to inefficient space utilization and potential air or liquid leakage caused by deformation under gas pressure.
Innovation Solution
A cap assembly design featuring a cap plate with an electrode lead-out hole, a fixing member with weakened portions, and a terminal board that covers the lead-out hole, where the fixing member is securely attached to the cap plate through a connecting member, and includes recesses and protrusions to prevent relative rotation, ensuring tight sealing and accommodating deformation without increasing the battery's internal space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conventional fixing member with large rigidity is used to fix the terminal board to the cap plate, then the terminal board is securely fixed, but the fixing member cannot deform along with the cap plate when gas is generated inside the case, causing gaps to increase and sealing to fail
Solution Approach 1:
The fixing member is designed with non-uniform thickness, having a first thickness in the region corresponding to the cap plate and a second thickness in the region corresponding to the terminal board, where the first thickness is greater than the second thickness. This local quality variation allows the fixing member to provide sufficient fixing strength while maintaining deformation adaptability to the cap plate's arching deformation.
Solution Approach 2:
The thickness parameter of the fixing member is changed across different regions to achieve the desired balance between fixing strength and deformation adaptability. The varying thickness allows the fixing member to have different mechanical properties in different zones, enabling it to both secure the terminal board and deform with the cap plate.
2Reliability
If the base portion of the terminal is located inside the case to be fixed by a clamp spring or riveting member, then the terminal is fixed to the cap plate, but space utilization inside the case is reduced and energy density is reduced
Solution Approach 1:
Instead of locating the base portion of the terminal inside the case and fixing it through the cap plate from the inside, the invention inverts the arrangement by locating the base portion outside the case and fixing it to the cap plate from the outside. This inversion allows the terminal to be securely fixed while maximizing the space utilization inside the case for active materials.
3Reliability
If numerous mechanical components are employed in the cap assembly to fix the terminal, then the terminal can be securely fixed, but the cost of the secondary battery increases and reliability is reduced
Solution Approach 1:
The fixing member integrates multiple functions into a single component: it provides structural support for the terminal board, acts as a fixing element to secure the terminal to the cap plate, and serves as a sealing element to prevent gas leakage. This merging of functions eliminates the need for separate clamp springs, riveting members, and sealing elements, thereby reducing the number of mechanical components.
Solution Approach 2:
The fixing member is designed as a multi-functional component that simultaneously performs fixing, sealing, and structural support functions. This universal design allows a single component to replace multiple specialized components, reducing overall device complexity while maintaining or improving reliability.
Data Source
AI summary
The present disclosure provides a cap assembly for a secondary battery and a secondary battery. The cap assembly includes a cap plate, a fixing member, a connecting member and an electrode terminal, wherein the cap plate has an electrode lead-out hole; the fixing member is fixed to the cap plate through the connecting member and provided with a weakened portion that is close to a center line of the cap plate in a width direction of the cap plate; and the electrode terminal includes a terminal board, wherein the terminal board has an outer peripheral surface at least partially surrounded by the fixing member so that the electrode terminal is fixed to the fixing member, and the terminal board is provided on a side of the cap plate and covers the electrode lead-out hole.