Cylindrical Battery Cell Core Hole Sizing for Winding Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cylindrical battery cells tend to overheat, leading to electrode delamination, short-circuits, and premature aging due to the low radius of curvature of initial windings, which causes the active material to detach from current collectors and forces electrolyte out of the separator, resulting in reduced battery life.
Innovation Solution
Increasing the diameter of the through hole in the core portion of the wound electrode assembly from 3 mm to a range of 4 to 7 mm reduces the mechanical stress on the initial windings, thereby minimizing delamination and allowing for improved cooling through a tubular sleeve, which relaxes the tap density of active material and reduces production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the through hole diameter is increased from 3 mm to 4-7 mm, then the mechanical stress on initial windings is reduced and delamination is minimized, but the device complexity increases due to modified winding structure
Solution Approach 1:
The invention changes the geometric parameter of the through hole diameter from the conventional 3 mm to a larger range of 4-7 mm. This parameter change reduces the curvature radius of the initial windings, thereby reducing mechanical stress and preventing delamination of active material from current collectors during battery cycling and thermal expansion.
2Temperature
If the through hole diameter is increased to 4-7 mm, then cooling efficiency is enhanced through improved tubular sleeve performance, but the manufacturing precision requirements increase for maintaining proper hole dimensions
Solution Approach 1:
The invention specifies a parameter range of 4-7 mm for the through hole diameter, which provides flexibility in manufacturing while ensuring adequate cooling performance. The tubular sleeve fitted within this enlarged hole improves heat dissipation from the electrode assembly to the electrolyte and cooling system.
3Ease of manufacture
If the through hole diameter is increased, then the tap density requirements for active material are relaxed and production costs are reduced, but the volume of the battery cell decreases
Solution Approach 1:
The invention relaxes the tap density requirement for active material by increasing the through hole diameter. This allows the use of less densely packed active material during manufacturing, reducing production complexity and costs. The enlarged core hole accommodates the winding structure with lower density requirements while maintaining adequate energy density through proper cell design.
Data Source
Figure 1~3
AI summary
A battery cell (1) comprising a wound electrode assembly (2) arranged in a cell casing (3), wherein said wound electrode assembly (2) comprises a positive electrode substrate (4) on which a positive electrode active material (5) is coated; a negative electrode substrate (6) on which a negative electrode active material (7) is coated; a separator (8) positioned between the positive and negative electrode substrates, wherein the separator (8) insulates a positive electrode (9) from a negative electrode (10); and core portion (11) of the wound electrode assembly, wherein said core portion (11) comprises a through hole (12) extending in a vertical direction (V) of said battery cell (1), and wherein said through hole (12) has a diameter (D) in the range of 4 to 7 mm.