Battery Current Collector Material for Camber-Stable Electrode Plates
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Solution Overview
Problem
The existing manufacturing process of secondary battery electrode plates experiences a camber phenomenon due to differences in elongation between coated and uncoated portions, leading to meandering defects and internal short circuits, which are difficult to mitigate without reducing energy density or increasing production costs.
Innovation Solution
A current collector with optimized elongation (1.5 to 3.0%) and tensile strength (25 to 35 kgf/mm2) is used, featuring a sheet shape with a controlled uncoated portion structure, allowing for minimal camber and improved processability, including notching and bending without breaking or cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the active material layer is coated on the current collector and compressed through rolling, then the energy density is improved, but the camber phenomenon occurs due to different elongation between coated and uncoated portions
Solution Approach 1:
The patent applies parameter changes by optimizing the elongation and tensile strength of the current collector to specific ranges (elongation: 1.5-3.0%, tensile strength: 25-35 kgf/mm²). This resolves the technical contradiction by adjusting material parameters to minimize camber while maintaining high energy density through effective active material coating and compression.
2Manufacturing precision
If the uncoated portion width is increased to prevent camber, then the manufacturing precision is improved, but the energy density is reduced due to less active material coverage
Solution Approach 1:
The patent resolves this contradiction by changing the parameters of the current collector (elongation and tensile strength) rather than increasing the uncoated portion width. This allows minimal uncoated portions to suffice for camber prevention while maximizing active material coverage and energy density.
Solution Approach 2:
The patent applies local quality by creating a small uncoated portion at the end of the current collector specifically for camber control, while the majority of the current collector surface maintains active material coating for high energy density. This localized approach prevents camber without sacrificing overall energy density.
3Ease of manufacture
If conventional current collectors with higher elongation are used, then the ease of manufacture is improved, but the meandering defect occurs during winding
Solution Approach 1:
The patent resolves this contradiction by optimizing the elongation parameter to a specific range (1.5-3.0%). This balanced parameter provides sufficient processability for manufacturing while preventing excessive elongation that would cause meandering defects during the winding process.
Solution Approach 2:
The patent applies preliminary action by pre-optimizing the current collector's tensile strength and elongation properties before the winding process. This preliminary material preparation ensures that the current collector maintains dimensional stability during subsequent winding operations, preventing meandering defects.
4Manufacturing precision
If additional heat treatment is performed to reduce camber, then the manufacturing precision is improved, but the production cost and complexity increase
Solution Approach 1:
The patent resolves this contradiction by changing the material parameters of the current collector (elongation and tensile strength) to inherently minimize camber formation during rolling. This eliminates the need for additional heat treatment processes, thereby reducing production complexity and costs while maintaining manufacturing precision.
Solution Approach 2:
The patent applies the extraction principle by removing the additional heat treatment step from the production process. Instead, it extracts and optimizes the key material parameters of the current collector to achieve camber control through the standard rolling process alone, thereby simplifying the overall manufacturing process.
Data Source
AI summary
A current collector for a secondary battery has a material having an elongation of 1.5 to 3.0% and a tensile strength of 25 to 35 kgf/mm2. An electrode, an electrode assembly, cylindrical battery cell, and battery pack are also provided.