Secondary Battery Tab Recess Depth for Stress Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion secondary batteries face breakage issues with current collection tabs during assembly due to high stress concentrations at joined portions, particularly when the battery capacity per unit volume is increased, leading to reduced space for other components and increased bending of tab members.
Innovation Solution
The design includes a secondary battery structure where the current collection tabs are joined to the current collection terminal members using ultrasonic waves, with a recessed form in the joined area, where the depth of the recessed form at the end closer to the electrode body is 50% or greater and 80% or less of the other joined portions, reducing stress concentration and preventing breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery capacity per unit volume is increased to reduce space for other components, then the energy density is improved, but the stress applied to the tab members and joined portions is increased, leading to breakage risk
Solution Approach 1:
The patent applies different recessed form depths to different joined portions based on their local stress conditions. The first joined portion (closer to electrode body) has a smaller recessed depth than the second joined portion, creating local structural differentiation that matches the stress distribution pattern during assembly, thereby preventing breakage while maintaining high energy density
Solution Approach 2:
The patent pre-designs recessed forms in the joined portions before assembly occurs. These recessed forms act as stress-absorbing features that cushion the impact of bending stress during the assembly process, preventing stress concentration that would otherwise cause tab member breakage
2Reliability
If the tab members are joined firmly to the current collectors, then the electrical connection is improved, but the stress concentration at the joined portions is increased, causing breakage during assembly
Solution Approach 1:
The patent creates local structural variation by setting different recessed depths for different joined portions. The first joined portion has a smaller recessed depth to maintain firm electrical connection, while the second joined portion has a larger recessed depth to reduce stress concentration and prevent breakage during assembly
Solution Approach 2:
The patent changes the geometric parameter (recessed depth) of the joined portions to optimize both electrical connection and mechanical strength. By controlling the recessed depth within specific ranges (first: 0.5-2.0mm, second: 2.0-3.0mm), the patent achieves a balance between connection reliability and stress resistance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively prevents breakage of current collection tabs during assembly and enhances the battery's vibration-resistant and impact-resistant capabilities, reducing product defects and ensuring strong electrical connections.
Implementation Method 1
the current collection tab and the current collection terminal member are joined by ultrasonic wave
Data Source
AI summary
A secondary battery includes: an electrode body which has a positive and a negative plate inserted in a battery case; a sealing plate which seals an opening in the case; and an external terminal attached thereto. One end of the positive and the negative plate is provided with a current collection tab, the one end closer to the sealing plate, the current collection tab is connected to the external terminal via a current collection terminal member disposed between the electrode body and the sealing plate, in a joined area between the current collection tab and the current collection. terminal member a joined portion of the current collection tab has a recessed form due to joining by ultrasonic wave, and a depth of the recessed form of a joined portion of an end closer to the electrode body is smaller than a depth of the recessed form of other joined portions.