Wound Electrode Assembly Overlap Structure Against Cracking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries, particularly cylindrical types, suffer from electrode deformation during charging/discharging due to expansion, leading to potential cracking and safety issues.
Innovation Solution
The electrode assembly design includes a first electrode substrate, separator, and second electrode substrate that extend beyond the distal end of the second electrode plate by at least one turn, forming an overlap to protect against deformation and cracking, with a finishing tape to secure the ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrode plates are made to accommodate expansion during charging/discharging, then capacity and energy density are improved, but electrode deformation and cracking occur leading to safety issues
Solution Approach 1:
The patent uses flexible finishing tapes (comprising polymer films) to wrap and secure the distal ends of the electrode assembly. These flexible films accommodate the expansion and contraction of electrode plates during charging/discharging cycles while maintaining structural integrity, preventing electrode deformation and cracking that would otherwise compromise safety
Solution Approach 2:
The finishing tapes are pre-installed at the distal ends of the electrode assembly to provide protective cushioning before any deformation occurs. This preliminary protection structure absorbs mechanical stress from electrode expansion, preventing cracking and maintaining reliability while allowing full capacity utilization
2Device complexity
If electrode assembly structure is simplified, then manufacturing cost and complexity are reduced, but structural integrity under pressure and heat resistance deteriorate
Solution Approach 1:
The patent employs thin polymer film tapes as finishing tapes to provide robust structural protection at the electrode assembly ends. These thin films deliver excellent heat resistance and mechanical strength without adding significant complexity to the manufacturing process, maintaining structural integrity under pressure and thermal conditions
Solution Approach 2:
The finishing tapes are constructed from composite polymer materials that combine multiple properties: heat resistance, mechanical strength, and flexibility. This composite material approach achieves high structural integrity and thermal resistance while keeping the design simple and manufacturable
3Reliability
If electrode substrate and separator extend beyond electrode plate, then protection against deformation and cracking is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies that the electrode substrate and separator extend beyond the electrode plate by a sufficient amount (at least one turn of the winding) to ensure complete coverage and protection of the distal end. This excessive extension ensures reliable protection against cracking while providing a practical manufacturing tolerance range, avoiding overly precise dimensional control requirements
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electrode assembly (100) including: a first electrode plate (110) including a first electrode substrate (111) having a first electrode active material layer (112) thereon; a first separator (120); a second electrode plate (130) including a second electrode substrate (131) having a second electrode active material layer (132) thereon; and a second separator (140). The first electrode plate (110), the first separator (120), the second electrode plate (130), and the second separator (140) are sequentially stacked and wound about a winding axis, and the first electrode substrate (111), the first separator (120), and the second separator (140) extend at least one turn beyond a distal end (130a) of the second electrode plate (130) in the wound electrode assembly (100).