Copper Foil Defect Prevention via Electroplating Control
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Solution Overview
Problem
Copper foils used in the roll-to-roll process for manufacturing secondary batteries often suffer from bagginess, wrinkles, or tears, leading to production inefficiencies and increased costs due to the need for frequent equipment stoppages and precise weight deviation control, which is insufficient in preventing these defects, especially with ultra-thin foils.
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, manufactured using an electrolyte with controlled current density and additives like 2-mercaptothiazoline and bis-(3-sulfopropyl) disulfide, to enhance its durability and prevent defects during the roll-to-roll process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the weight deviation of the copper foil is controlled to a low level, then the occurrence of bagginess, wrinkle and tear defects is reduced, but this control method has limitations in completely solving these problems, especially with ultra-thin copper foils
Solution Approach 1:
The patent changes the physical and chemical parameters of the copper foil by controlling the electrolyte composition (adding 2-mercaptothiazoline and bis-(3-sulfopropyl) disulfide), current density (30-80 A/dm2), and temperature (20-40°C) during electroplating to achieve optimal tensile strength (29-65 kgf/mm2) and surface roughness (Rsm: 18-148 μm), thereby preventing defects without relying solely on weight deviation control
Solution Approach 2:
The patent creates a composite structure by forming a copper foil with controlled crystal texture (TCB(220) ≤ 0.52) and specific surface roughness characteristics through electrolyte additives, resulting in a material that combines both weight uniformity and mechanical durability to prevent bagginess, wrinkles and tears
2Quantity of substance
If an ultra-thin copper foil (8 μm or less) is used to increase the capacity of secondary batteries, then the energy density is improved, but bagginess, wrinkle and tear defects intermittently occur in the manufacturing process
Solution Approach 1:
The patent applies specific electroplating parameters including current density (30-80 A/dm2), electrolyte composition with additives (2-mercaptothiazoline: 2-20 mg/L, bis-(3-sulfopropyl) disulfide: 2-20 mg/L), and temperature (20-40°C) to produce ultra-thin copper foils with optimized tensile strength (29-65 kgf/mm2) and surface roughness (Rsm: 18-148 μm), enabling defect-free manufacturing of high-capacity batteries
Solution Approach 2:
The patent creates local quality variations in the copper foil structure by controlling the surface roughness profile (Rsm: 18-148 μm, Rmax: 0.6 μm or more) and crystal texture distribution (TCB(220) ≤ 0.52) through electrolyte additives, providing localized mechanical properties that prevent defect formation while maintaining ultra-thin overall thickness
3Productivity
If the roll-to-roll process is operated continuously for mass production, then the productivity is improved, but the copper foil is folded, torn or suffers bagginess or wrinkles requiring equipment stoppages
Solution Approach 1:
The patent performs preliminary action by optimizing the copper foil properties before the roll-to-roll process through controlled electroplating with specific electrolyte composition and parameters, pre-establishing the tensile strength (29-65 kgf/mm2) and surface roughness (Rsm: 18-148 μm) needed to withstand continuous processing without defects
Solution Approach 2:
The patent changes the physical parameters of the copper foil by controlling electrolyte composition (adding 2-mercaptothiazoline and bis-(3-sulfopropyl) disulfide), current density (30-80 A/dm2), and temperature (20-40°C) during electroplating to achieve optimal tensile strength (29-65 kgf/mm2) and surface roughness (Rsm: 18-148 μm), thereby preventing defects without relying solely on weight deviation control
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 resistance to bagginess, wrinkles, and tears, ensuring stable production and increased efficiency in the roll-to-roll process, making it suitable for high-capacity secondary batteries with minimized defects and enhanced manufacturing efficiency.
Implementation Method 1
applying a current density of 30 to 80 A/dm2 to an electrode plate and a rotary electrode drum spaced from each other in an electrolyte containing copper ions to form a copper layer
Implementation Method 2
manufactured using an electrolyte with controlled current density and additives like 2-mercaptothiazoline and bis-(3-sulfopropyl) disulfide, to enhance its durability
Data Source
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.