Cylindrical Battery Cell Core Structure to Reduce Inner Winding Stress
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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 lifespan.
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 inner windings, thereby minimizing delamination and allowing for improved cooling with a tubular sleeve for coolant flow.
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 inner windings is reduced and delamination is minimized, but the structural complexity of the core portion increases
Solution Approach 1:
The patent applies parameter changes by modifying the through hole diameter from 3 mm to 4-7 mm, which fundamentally alters the mechanical stress distribution in the inner windings. This parameter change reduces curvature stress and prevents delamination without requiring complex additional components, thus improving reliability while maintaining relatively simple structure.
2Temperature
If the through hole diameter is increased to 4-7 mm, then cooling efficiency is improved with tubular sleeve, but the volume of the battery cell increases
Solution Approach 1:
The patent implements the nested doll principle by placing a tubular sleeve inside the enlarged through hole of the core portion. This nested structure allows the cooling system to be integrated within the existing battery cell volume, improving heat dissipation through the sleeve while minimizing the overall volume increase that would result from simply enlarging the through hole.
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 reduces premature aging, relaxes the tap density requirements for active material, and decreases production costs while enhancing the battery cell's durability and longevity.
Implementation Method 1
The tubular sleeve may be formed from the same material as the casing material, and may provide the technical effect of providing for a flow pathway of for instance a liquid coolant on the inside of the battery cell
Data Source
AI summary
A battery cell includes a wound electrode assembly arranged in a cell casing. The wound electrode assembly includes a positive electrode substrate on which a positive electrode active material is coated; a negative electrode substrate on which a negative electrode active material is coated; a separator positioned between the positive and negative electrode substrates, wherein the separator insulates a positive electrode from a negative electrode; and core portion of the wound electrode assembly. The core portion includes a through hole extending in a vertical direction of said battery cell, and wherein said through hole has a diameter in the range of 4 to 7 mm.