Anode Current Collector Creep Control for Jelly-Roll Battery Assemblies
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Solution Overview
Problem
Existing jelly-roll type electrode assemblies in secondary batteries, particularly those using silicon-based anode active materials, suffer from deformation, expansion, and internal disconnection due to stress differences between round and flat parts during charging and discharging, which conventional fixing methods like winding tapes cannot adequately address.
Innovation Solution
The anode current collector in the jelly-roll type electrode assembly is designed to have a specific creep rate range (20 μm/sec to 50 μm/sec) and tensile strength of 20 kg/mm² to 45 kg/mm², using materials like copper, aluminum, or stainless steel, with an anode mixture layer containing silicon and carbon materials, to manage stress and prevent deformation and internal disconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase charge-discharge capacity, then battery capacity is improved, but stress accumulation in anode plate increases causing internal disconnection risk
Solution Approach 1:
The patent applies parameter changes by precisely controlling the creep rate of the anode current collector within a specific range (20-50 μm/sec at 300 MPa and 22±2°C). This parameter optimization allows the current collector to adequately deform and absorb stress generated by silicon-based active material during charge-discharge cycles, preventing internal disconnection while maintaining high capacity
Solution Approach 2:
The patent uses composite materials by combining silicon-based active material with carbon materials in the anode mixture layer. This composite structure leverages the high capacity of silicon while carbon provides structural stability and stress distribution, reducing the overall stress accumulation on the current collector and preventing internal disconnection
2Shape
If winding fixing tape is introduced to suppress electrode assembly swelling, then assembly deformation is reduced, but internal disconnection of anode plate cannot be prevented due to high stress accumulation
Solution Approach 1:
The patent changes the critical parameter of the anode current collector by optimizing its creep rate to a specific range (20-50 μm/sec). This material parameter adjustment enables the current collector itself to function as a stress-absorbing component, providing internal stress relief that external fixing tapes cannot achieve, thereby preventing both deformation and internal disconnection
Solution Approach 2:
The patent introduces the anode current collector as an intermediary stress-absorbing layer between the anode active material and the external environment. By controlling its creep characteristics, it mediates the stress transmission, protecting the anode plate from stress concentration while maintaining structural integrity, something that fixing tapes alone cannot accomplish
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 controls electrode assembly deformation and expansion, reduces stress accumulation, and prevents internal disconnection, ensuring high safety and capacity retention in secondary batteries.
Implementation Method 1
when the creep rate of the anode current collector is measured under tensile force condition of 22±2° C. and 300 MPa, the anode current collector satisfies Formula 1 below by falling in between 20 μm/sec to 50 μm/sec
Data Source
AI summary
An anode for a secondary battery and a jelly-roll type electrode assembly including the anode. The anode includes an anode current collector that satisfies a creep rate condition represented by Formula 1 within a certain range. When the anode is applied to the jelly-roll type electrode assembly, deformation and/or expansion of electrode assembly can be controlled, even if it contains a silicon-containing anode active material because the stress generated from the exterior is significantly low. It is possible to ensure excellent safety because the stress accumulated in the anode current collector is greatly reduced, which lowers the risk of an internal disconnection of the electrode assembly.