Copper Foil Surface Control for Uniform Battery Electrode Coating
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Solution Overview
Problem
Lithium secondary batteries face issues with non-uniform coating of active materials on copper foils due to surface roughness and inadequate additives during electroplating, leading to potential short circuits and delamination, which affects charge/discharge capacity and battery yield.
Innovation Solution
A copper foil with a surface structure optimized for uniform active material coating, characterized by a color difference coefficient of 0.38 to 0.7 based on the Lab color system, and a manufacturing method involving a specific electrolyte composition and protective layer formation to enhance surface characteristics and elongation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface roughness is increased to improve active material coating, then coating uniformity is improved, but short circuit risk increases due to excessive unevenness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the color difference coefficient (ΔE) within a specific range (0.38 to 0.7) to optimize surface characteristics. This quantitative parameter control ensures the surface is sufficiently rough for uniform active material coating while preventing excessive unevenness that would cause short circuits, thereby resolving the contradiction between coating uniformity and short circuit prevention.
Solution Approach 2:
The patent replaces direct mechanical measurement of surface roughness with an optical measurement approach using color difference coefficient (ΔE). This substitution allows for more precise and comprehensive characterization of surface properties, enabling better control over the balance between coating uniformity and short circuit prevention without relying solely on traditional roughness measurements.
2Manufacturing precision
If additives are increased during electroplating to improve surface characteristics, then coating uniformity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent simplifies the electroplating process by replacing complex multiple additive formulations with precise control of the color difference coefficient (ΔE) as a key parameter. This single parameter control approach achieves uniform coating while avoiding the complexity of managing multiple additive types and concentrations, thereby resolving the contradiction between coating uniformity and manufacturing complexity.
Solution Approach 2:
The patent extracts and focuses on the most critical parameter (color difference coefficient ΔE) from the complex electroplating process, separating it from other less critical variables. This extraction allows for simplified process control by concentrating optimization efforts on the single most important parameter that directly affects coating uniformity, reducing overall process complexity.
3Manufacturing precision
If color difference coefficient is decreased to improve surface uniformity, then coating uniformity is improved, but surface roughness becomes insufficient leading to poor adhesion
Solution Approach 1:
The patent identifies and controls the color difference coefficient (ΔE) as the critical parameter that simultaneously governs both coating uniformity and adhesion strength. By maintaining ΔE within the optimal range of 0.38 to 0.7, the patent achieves the dual benefit of uniform coating and strong adhesion, resolving the contradiction between these two requirements through precise parameter optimization.
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 optimized copper foil ensures uniform active material coating, reducing the risk of short circuits and delamination, thereby improving charge/discharge efficiency and extending battery lifespan.
Implementation Method 1
forming the copper film includes forming the copper film on a rotating anode drum by electrically connecting a cathode plate and the rotating anode drum, which are disposed to be spaced apart from each other in an electrolyte in an electrolytic bath
Implementation Method 2
the electrolyte includes copper ions at a concentration of 70 g/L to 100 g/L, sulfuric acid at a concentration of 70 g/L to 150 g/L, chlorine (Cl) at a concentration of 1 ppm to 3 ppm, hydrogen peroxide at a concentration of 1 ml/L to 10 ml/L, silver ions (Ag+) at a concentration of 0.1 ppm to 1.0 ppm, cerium ions (Ce2+) at a concentration of 2 ppm to 10 ppm, and lead ions (Pb2+) at a concentration of 1 ppm to 20 ppm
Data Source
AI summary
According to one embodiment of the present disclosure, there is provided a copper foil including a copper film having 99.9 wt % or more of copper, wherein the copper foil has a color difference coefficient in a range of 0.38 to 0.7 based on the Lab color system.