Prismatic Battery Terminal Joining Strength and Resistance Stability
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Solution Overview
Problem
Existing prismatic secondary batteries face challenges in achieving strong joining strength and reliable electrical continuity between the external terminal and terminal plate, particularly due to differences in material strength between the positive and negative electrode sides, leading to variations in internal resistance and potential weaknesses in the crimped and weld portions.
Innovation Solution
A prismatic secondary battery design that incorporates crimped portions and weld spots formed by high energy beams on both the positive and negative electrode sides, with varying contact areas and volumes to ensure robust mechanical and electrical connections, and the use of aluminum-based metals for the positive electrode and copper-based metals for the negative electrode, along with a pressure-sensitive current interruption mechanism for safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If mechanical crimping is used to connect the external terminal and terminal plate, then the joining strength is improved, but the electrical resistance varies over time under vibration environments
Solution Approach 1:
The patent combines mechanical crimping with high energy beam welding to create a hybrid joint. The crimped portion provides initial mechanical strength and contact, while the weld spots formed by high energy beams (laser or electron beam) provide stable electrical continuity. This merging of mechanical and thermal joining methods resolves the contradiction by maintaining both strong joining strength and stable electrical resistance under vibration conditions.
Solution Approach 2:
The joint structure uses composite joining methods - mechanical deformation (crimping) combined with metallurgical bonding (welding). The crimped portion creates cold-welded contact while the high energy beam welding creates additional metallurgical bonds, forming a composite joint that leverages the advantages of both joining mechanisms to achieve both strength and electrical stability.
2Reliability
If the boundary portion is entirely welded with high energy beams, then the electrical continuity is improved, but the crimping force becomes weak due to melting
Solution Approach 1:
Instead of uniformly welding the entire boundary portion, the patent applies high energy beam welding locally at specific weld spots along the crimped joint. This local welding approach provides sufficient electrical continuity at critical contact points while preserving the mechanical crimping force in the non-welded portions. The selective application of welding heat avoids melting the entire crimped structure.
Solution Approach 2:
The patent uses partial welding action - applying high energy beams to create discrete weld spots rather than continuous welding. This partial action provides just enough electrical continuity through the weld spots while avoiding excessive heat input that would compromise the overall crimping force. The intermittent welding pattern balances electrical and mechanical requirements.
3Reliability
If multiple weld spots are formed to improve electrical continuity, then the internal resistance is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent replaces complex mechanical multi-point contact systems with a simplified high energy beam welding system. Instead of relying on extensive mechanical crimping at multiple points to ensure electrical continuity, the high energy beam welding creates precise metallurgical bonds that provide equivalent or superior electrical pathways with potentially simpler process control. The energy beam system can be programmed to create the necessary weld pattern automatically.
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
The design achieves strong joining strength and torque strength between the external terminal and terminal plate, reduces internal resistance variations, and enhances reliability while maintaining safety through the pressure-sensitive current interruption mechanism.
Implementation Method 1
welding with high energy beams such as laser beams
Implementation Method 2
weld spots formed by application of high energy beams
Data Source
AI summary
A crimped portion of a positive electrode external terminal is crimped on its upper end side to be electrically connected to a positive electrode terminal plate. This crimped portion is welded to the positive electrode terminal plate by applying high energy beams. The negative electrode side has a configuration similar to that of the positive electrode side. The contact area between the positive electrode terminal plate and the crimped portion of the positive electrode external terminal is set smaller than the corresponding contact area on the negative electrode side, and the volume of the crimped portion of the positive electrode external terminal is set larger than that of the corresponding crimped portion on the negative electrode side. Thus, a prismatic secondary battery is provided that shows strong joining strength between the external terminal and the terminal plate, suppressed internal resistance variations, and improved reliability.