Ultrathin Copper Foil Defect Prevention via Texture Control
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Solution Overview
Problem
Copper foils used in the manufacturing of secondary batteries often suffer from bagginess, wrinkle, and tear issues during the roll-to-roll process, leading to production inefficiencies and increased costs, especially with the use of ultrathin foils, which are prone to defects despite controlled weight deviation.
Innovation Solution
A copper foil with specific properties, including a tensile strength of 29 to 65 kgf/mm², a mean width of roughness profile elements of 18 to 148 µm, a texture coefficient bias of 0.52 or less, and an anticorrosive film, is developed, along with a manufacturing method involving a current density of 30 to 80 A/dm² and a controlled electrolyte composition to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ultrathin copper foil is used to increase battery capacity, then energy density is improved, but the foil becomes more prone to bagginess, wrinkle and tear defects
Solution Approach 1:
The patent applies parameter changes by precisely controlling the thickness of the copper foil within 3.8 μm to 10 μm and managing the weight deviation at 5% or less. This optimization of dimensional parameters enables the foil to maintain sufficient mechanical strength and flexibility simultaneously, preventing bagginess, wrinkles, and tears while achieving high battery capacity through ultrathin design.
2Manufacturing precision
If weight deviation is controlled to remove the cause of defects, then manufacturing precision is improved, but bagginess, wrinkle and tear defects still occur intermittently
Solution Approach 1:
The patent extends parameter control beyond weight deviation to include thickness uniformity (3.8-10 μm) and surface roughness parameters (Ra ≤ 0.8 μm). This multi-parameter optimization approach ensures that the copper foil maintains consistent mechanical properties throughout the roll-to-roll process, eliminating intermittent defects that occur even when weight deviation is controlled.
Solution Approach 2:
The patent implements feedback control through continuous monitoring and adjustment of plating parameters during manufacturing. By measuring and controlling thickness, weight deviation, and surface roughness in real-time, the system can detect and correct deviations before they cause defects, ensuring stable process operation and consistent foil quality.
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
The copper foil exhibits improved roll-to-roll processability, reducing the occurrence of bagginess, wrinkle, and tear, thereby enhancing manufacturing efficiency and the stability of secondary batteries.
Implementation Method 1
Copper foils are used to manufacture a variety of products such as anodes for secondary batteries and flexible printed circuit boards (FPCBs). Meanwhile, a copper foil manufactured by electroplating is referred to as an 'electrolytic copper foil'.
Implementation Method 2
a copper foil manufactured by electroplating is referred to as an 'electrolytic copper foil'
Data Source
Figure 1~2A
Figure 2B~3
Figure 4~5
AI summary
Disclosed is a copper foil including a copper layer and having a tensile strength of 29 to 65 kgf/mm2, a mean width of roughness profile elements (Rsm) of 18 to 148 µm and a texture coefficient bias [TCB(220)] of 0.52 or less.