Electrolytic Copper Foil Drum Side Hardness Control
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Solution Overview
Problem
Conventional electrolytic copper foils for lithium-ion batteries suffer from mechanical weaknesses, such as wrinkles and cracks, which reduce production yield and cycle performance due to stress differences during the coating and pressing process.
Innovation Solution
The electrolytic copper foil is optimized by controlling the nanoindentation hardness and lightness of its drum side, achieved by moistening the cathode drum surface before electroplating and using specific polishing wheel models, to enhance mechanical properties and prevent damage during processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional electrolytic copper foil is used with standard hardness, then the manufacturing process is simple, but the foil suffers from wrinkles and cracks during pressing due to stress differences
Solution Approach 1:
The patent applies parameter changes by precisely controlling the nanoindentation hardness of the drum side within 0.5-3.5 GPa and lightness within 25-75. This parameter optimization resolves the contradiction by enhancing mechanical strength to prevent wrinkles and cracks during pressing, while maintaining a relatively simple electrolytic copper foil manufacturing process without adding complex multi-layer structures.
2Weight of moving object
If the copper foil is made thinner to reduce weight, then the energy density improves, but the mechanical strength decreases making it more prone to breaking
Solution Approach 1:
The patent applies local quality by creating a differentiated surface structure where the drum side has optimized hardness (0.5-3.5 GPa) and lightness (25-75) properties. This localized property optimization allows the foil to maintain thin dimensions for high energy density while the enhanced drum side properties provide the necessary mechanical strength to prevent breaking during handling and processing.
3Strength
If repeated rolling and annealing steps are used to improve copper foil quality, then the mechanical properties improve, but the production cost increases and width is limited
Solution Approach 1:
The patent replaces the conventional mechanical rolling and annealing system with an electrolytic deposition process. By controlling the nanoindentation hardness and lightness parameters during electrolytic copper foil formation, the method achieves improved mechanical properties without the need for repeated rolling and annealing steps, thereby reducing production cost and enabling broader width manufacturing.
4Strength
If the drum side hardness is increased to prevent deformation, then the resistance to pressing stress improves, but the lightness decreases affecting coating uniformity
Solution Approach 1:
The patent applies parameter changes by establishing an optimized range for both nanoindentation hardness (0.5-3.5 GPa) and lightness (25-75) of the drum side. This dual parameter optimization resolves the contradiction by finding the balance point where sufficient hardness provides resistance to pressing stress while adequate lightness maintains coating uniformity, preventing both over-hardening and over-softening issues.
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
This approach improves the production yield and cycle performance of lithium-ion batteries by mitigating wrinkles and breakages, resulting in a longer service life and higher commercial potential for the electrolytic copper foil.
Implementation Method 1
electrolyzing the copper sulfate electrolyte solution to deposit the electrolytic copper foil on the surface of the cathode drum
Implementation Method 2
supplying a copper sulfate electrolyte solution between an anode and a cathode drum, electrolyzing the copper sulfate electrolyte solution to deposit the electrolytic copper foil on the surface of the cathode drum
Data Source
AI summary
Provided are an electrolytic copper foil, an electrode comprising the same, and a lithium ion battery comprising the same. The electrolytic copper foil has a drum side and a deposited side opposing to the drum side, wherein a nanoindentation hardness of the drum side is equal to or larger than 0.5 GPa and equal to or smaller than 3.5 GPa; and a lightness of the drum side is equal to or larger than 25 and equal to or smaller than 75.