Ultra-Thin Copper Foil Friction Control for Roll-to-Roll Electrodes
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Solution Overview
Problem
The slipping phenomenon between a roll and ultra-thin copper foil during the manufacturing process of secondary batteries leads to wrinkles and tears, compromising the workability and handleability of the electrode forming process, especially when the copper foil thickness is reduced below 10 μm.
Innovation Solution
A copper foil with a matte and shiny surface configuration, along with a protective layer, is developed, ensuring a specific range of tensile strength and kinetic friction coefficient to prevent slipping and ensure uniform coating of active materials, using an electrolyte composition including copper ions, sulfuric acid, chlorine, and organic additives for manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the thickness of copper foil is reduced below 10 μm to increase battery capacity, then the capacity of secondary battery is improved, but slipping phenomenon occurs between roll and copper foil during manufacturing
Solution Approach 1:
The patent applies parameter changes by controlling the kinetic friction coefficient within a specific range (0.05-0.15) through electrolyte composition optimization and surface treatment. This resolves the contradiction by adjusting friction parameters to prevent slipping of ultra-thin copper foil while maintaining the reduced thickness for high battery capacity.
Solution Approach 2:
The patent uses composite materials by creating a copper foil with dual surface characteristics (matte and shiny surfaces with different friction coefficients) and applying protective coatings. This composite structure maintains low thickness for capacity while the varied surface properties prevent slipping during manufacturing.
2Quantity of substance
If the thickness of copper foil is reduced below 10 μm, then battery capacity is improved, but wrinkles and tears occur in copper foil during manufacturing
Solution Approach 1:
The patent optimizes tensile strength parameters to ≥3.0 kgf/mm² through controlled electrolyte composition and surface treatment. This parameter optimization allows ultra-thin copper foil to maintain structural integrity and resist wrinkles and tears while achieving high battery capacity through reduced thickness.
Solution Approach 2:
The patent applies beforehand cushioning by optimizing the copper foil's mechanical properties (tensile strength ≥3.0 kgf/mm²) and surface characteristics before the manufacturing process. This pre-conditioning prevents wrinkles and tears from occurring during subsequent handling and manufacturing operations.
3Reliability
If the kinetic friction coefficient is increased to prevent slipping, then slipping is prevented, but tensile strength may be compromised
Solution Approach 1:
The patent precisely controls the kinetic friction coefficient within the optimal range of 0.05-0.15 and tensile strength at ≥3.0 kgf/mm² through electrolyte composition optimization and surface treatment parameters. This dual parameter optimization resolves the contradiction by achieving both slipping prevention and adequate tensile strength simultaneously.
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 maintains excellent tensile strength and prevents slipping and tears during manufacturing, allowing for uniform active material coating and improved roll-to-roll processability, enhancing the production efficiency of secondary batteries.
Implementation Method 1
forming of the copper film includes allowing a cathode plate and a rotating anode drum disposed to be spaced apart from each other in an electrolyte in an electrolytic cell to conduct current to form the copper film on the rotating anode drum
Implementation Method 2
the organic additive includes a polishing agent (component A), a moderator (component B), and a leveling agent (component C)
Data Source
AI summary
One embodiment of the present disclosure provides a copper foil including a copper film having a matte surface and a shiny surface, and a protective layer disposed on the copper film, wherein the copper film has a first surface in a direction of the matte surface and a second surface in a direction of the shiny surface, and Equation 1 below is satisfied.3.0 kgf/mm2≤tensile strength×average kinetic friction coefficient≤8.0 kgf/mm2, [Equation 1]the average kinetic friction coefficient in Equation 1 means an average value of kinetic friction coefficients of the first surface and the second surface.