Copper Foil Surface Structure for Battery Electrode Adhesion
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Solution Overview
Problem
The detachment of active materials from copper foils during charging and discharging in secondary batteries reduces the lifespan of the battery due to insufficient adhesive strength between the copper foil and the active material.
Innovation Solution
A copper foil with a matte and shiny surface, coated with a protective layer, is manufactured using a specific electrolytic process involving controlled electrolyte composition and conditions to achieve a peak density and gloss ratio within a specified range, ensuring uniform coating and enhanced adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a copper foil with conventional surface properties is used, then the manufacturing process is simple, but the adhesive strength between the copper foil and active material is insufficient
Solution Approach 1:
The copper foil surface is designed with dual-zone characteristics: a matte surface region providing high roughness for mechanical interlocking with active material, and a shiny surface region providing smoothness for uniform coating application. This local differentiation of surface properties enables simultaneous achievement of strong adhesion and uniform coating without complex additional structures
Solution Approach 2:
The copper foil incorporates a composite surface structure combining two distinct surface morphologies (matte and shiny) on the same substrate. This composite surface architecture allows different regions to fulfill different functional requirements: the matte region maximizes adhesive strength through roughness, while the shiny region ensures uniform coating deposition
2Strength
If the copper foil surface is made rough to increase adhesion, then the adhesive strength improves, but the uniformity of coating becomes poor
Solution Approach 1:
By creating distinct matte and shiny regions on the copper foil surface, the invention localizes the roughness function to matte regions for adhesion while reserving shiny regions for uniform coating application. This spatial separation of functions resolves the conflict between adhesion enhancement and coating uniformity
3Manufacturing precision
If the copper foil surface is made smooth for uniform coating, then the coating uniformity improves, but the adhesive strength decreases
Solution Approach 1:
The copper foil surface is engineered with spatially differentiated properties where shiny regions provide smooth surfaces for uniform coating deposition, while matte regions provide rough surfaces for high adhesive strength. This local quality differentiation allows each region to optimize for its specific function without compromising the other
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 solution provides a copper foil with improved adhesive strength, enhancing the lifespan and reliability of secondary batteries by maintaining uniform coating and secure adhesion with the active material.
Implementation Method 1
forming a 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 electrolyte includes 70 to 150 g/L of copper ions, 80 to 150 g/L of sulfuric acid, 15 to 25 ppm of chlorine (Cl), and an organic additive
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.45≤[(average 60° gloss)/(G.U.)×(average peak density)/(count)]/100≤70, [Equation 1]the average peak density in Equation 1 means an average value of peak densities of the first surface and the second surface, the peak density means a value acquired by dividing a peak count roughness (Rpc) by a surface area ratio, and the average 60° gloss in Equation 1 means an average value of 60° glosses of the first surface and the second surface.